Nondestructive Evaluation Approaches Developed for Material Characterization in Aeronautics and Space Applications

NASA Technical Reports Server (NTRS)

Baaklini, George Y.; Kautz, Harold E.; Gyekenyesi, Andrew L.; Abdul-Aziz, Ali; Martin, Richard E.

2001-01-01

At the NASA Glenn Research Center, nondestructive evaluation (NDE) approaches were developed or tailored for characterizing advanced material systems. The emphasis was on high-temperature aerospace propulsion applications. The material systems included monolithic ceramics, superalloys, and high-temperature composites. In the aeronautics area, the major applications were cooled ceramic plate structures for turbine applications, gamma-TiAl blade materials for low-pressure turbines, thermoelastic stress analysis for residual stress measurements in titanium-based and nickel-based engine materials, and acousto-ultrasonics for creep damage assessment in nickel-based alloys. In the space area, applications consisted of cooled carbon-carbon composites for gas generator combustors and flywheel rotors composed of carbon-fiber-reinforced polymer matrix composites for energy storage on the International Space Station.

In vitro bioactivity, cytocompatibility, and antibiotic release profile of gentamicin sulfate-loaded borate bioactive glass/chitosan composites.

PubMed

Cui, Xu; Gu, Yifei; Li, Le; Wang, Hui; Xie, Zhongping; Luo, Shihua; Zhou, Nai; Huang, Wenhai; Rahaman, Mohamed N

2013-10-01

Borate bioactive glass-based composites have been attracting interest recently as an osteoconductive carrier material for local antibiotic delivery. In the present study, composites composed of borate bioactive glass particles bonded with a chitosan matrix were prepared and evaluated in vitro as a carrier for gentamicin sulfate. The bioactivity, degradation, drug release profile, and compressive strength of the composite carrier system were studied as a function of immersion time in phosphate-buffered saline at 37 °C. The cytocompatibility of the gentamicin sulfate-loaded composite carrier was evaluated using assays of cell proliferation and alkaline phosphatase activity of osteogenic MC3T3-E1 cells. Sustained release of gentamicin sulfate occurred over ~28 days in PBS, while the bioactive glass converted continuously to hydroxyapatite. The compressive strength of the composite loaded with gentamicin sulfate decreased from the as-fabricated value of 24 ± 3 MPa to ~8 MPa after immersion for 14 days in PBS. Extracts of the soluble ionic products of the borate glass/chitosan composites enhanced the proliferation and alkaline phosphatase activity of MC3T3-E1 cells. These results indicate that the gentamicin sulfate-loaded composite composed of chitosan-bonded borate bioactive glass particles could be useful clinically as an osteoconductive carrier material for treating bone infection.

An artificial photosynthesis anode electrode composed of a nanoparticulate photocatalyst film in a visible light responsive GaN-ZnO solid solution system

PubMed Central

Imanaka, Yoshihiko; Anazawa, Toshihisa; Manabe, Toshio; Amada, Hideyuki; Ido, Sachio; Kumasaka, Fumiaki; Awaji, Naoki; Sánchez-Santolino, Gabriel; Ishikawa, Ryo; Ikuhara, Yuichi

2016-01-01

The artificial photosynthesis technology known as the Honda-Fujishima effect, which produces oxygen and hydrogen or organic energy from sunlight, water, and carbon dioxide, is an effective energy and environmental technology. The key component for the higher efficiency of this reaction system is the anode electrode, generally composed of a photocatalyst formed on a glass substrate from electrically conductive fluorine-doped tin oxide (FTO). To obtain a highly efficient electrode, a dense film composed of a nanoparticulate visible light responsive photocatalyst that usually has a complicated multi-element composition needs to be deposited and adhered onto the FTO. In this study, we discovered a method for controlling the electronic structure of a film by controlling the aerosol-type nanoparticle deposition (NPD) condition and thereby forming films of materials with a band gap smaller than that of the prepared raw material powder, and we succeeded in extracting a higher current from the anode electrode. As a result, we confirmed that a current approximately 100 times larger than those produced by conventional processes could be obtained using the same material. This effect can be expected not only from the materials discussed (GaN-ZnO) in this paper but also from any photocatalyst, particularly materials of solid solution compositions. PMID:27759108

Electrical/Mechanical Monitoring of Shape Memory Alloy Reinforcing Fibers Obtained by Pullout Tests in SMA/Cement Composite Materials.

PubMed

Kim, Eui-Hyun; Lee, Hyunbae; Kim, Jae-Hwan; Bae, Seung-Muk; Hwang, Heesu; Yang, Heesun; Choi, Eunsoo; Hwang, Jin-Ha

2018-02-22

Self-healing is an essential property of smart concrete structures. In contrast to other structural metals, shape memory alloys (SMAs) offer two unique effects: shape memory effects, and superelastic effects. Composites composed of SMA wires and conventional cements can overcome the mechanical weaknesses associated with tensile fractures in conventional concretes. Under specialized environments, the material interface between the cementitious component and the SMA materials plays an important role in achieving the enhanced mechanical performance and robustness of the SMA/cement interface. This material interface is traditionally evaluated in terms of mechanical aspects, i.e., strain-stress characteristics. However, the current work attempts to simultaneously characterize the mechanical load-displacement relationships synchronized with impedance spectroscopy as a function of displacement. Frequency-dependent impedance spectroscopy is tested as an in situ monitoring tool for structural variations in smart composites composed of non-conducting cementitious materials and conducting metals. The artificial geometry change in the SMA wires is associated with an improved anchoring action that is compatible with the smallest variation in resistance compared with prismatic SMA wires embedded into a cement matrix. The significant increase in resistance is interpreted to be associated with the slip of the SMA fibers following the elastic deformation and the debonding of the SMA fiber/matrix.

Characterization of Carbon Nanotube Reinforced Nickel

NASA Technical Reports Server (NTRS)

Gill, Hansel; Hudson, Steve; Bhat, Biliyar; Munafo, Paul M. (Technical Monitor)

2002-01-01

Carbon nanotubes are cylindrical molecules composed of carbon atoms in a regular hexagonal arrangement. If nanotubes can be uniformly dispersed in a supporting matrix to form structural materials, the resulting structures could be significantly lighter and stronger than current aerospace materials. Work is currently being done to develop an electrolyte-based self-assembly process that produces a Carbon Nanotube/Nickel composite material with high specific strength. This process is expected to produce a lightweight metal matrix composite material, which maintains it's thermal and electrical conductivities, and is potentially suitable for applications such as advanced structures, space based optics, and cryogenic tanks.

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.

DIGEST MATERIALS FOR IMPROVING AND EXTENDING THE JUNIOR HIGH SCHOOL ORCHESTRA REPERTORY. VOLUME 2, CLASSICAL.

ERIC Educational Resources Information Center

MOORE, JUNE

PREPARED AS PART OF "PROJECT IMPROVING AND EXTENDING THE JUNIOR HIGH SCHOOL ORCHESTRA REPERTORY," THIS VOLUME CONTAINS CURRICULAR MATERIALS REPRESENTING THE CLASSICAL PERIOD. A HISTORY OF THE PERIOD IS GIVEN, AS WELL AS HISTORIES OF THE COMPOSERS AND THEIR INDIVIDUAL COMPOSITIONS. THE MATERIALS ARE PREPARED FOR FOUR DEGREES OF TECHNICAL…

DIGEST MATERIALS FOR IMPROVING AND EXTENDING THE JUNIOR HIGH SCHOOL ORCHESTRA REPERTORY. VOLUME 3, ROMANTIC.

ERIC Educational Resources Information Center

MOORE, JUNE

PREPARED AS PART OF "PROJECT IMPROVING AND EXTENDING THE JUNIOR HIGH SCHOOL ORCHESTRA REPERTORY," THIS VOLUME CONTAINS CURRICULAR MATERIALS REPRESENTING THE ROMANTIC PERIOD. A MUSICAL HISTORY OF THE PERIOD IS GIVEN, AS WELL AS HISTORIES OF THE COMPOSERS AND THEIR INDIVIDUAL COMPOSITIONS. THE MATERIALS ARE PREPARED FOR THREE DEGREES OF TECHNICAL…

New organic photorefractive material composed of a charge-transporting dendrimer and a stilbene chromophore

NASA Astrophysics Data System (ADS)

Bai, Jaeil; Ducharme, Stephen; Leonov, Alexei G.; Lu, Liu; Takacs, James M.

1999-10-01

In this report, we introduce new organic photorefractive composites consisting of charge transporting den-drimers highly doped with a stilbene nonlinear optic chromophore, The purpose of making these composites is to improve charge transport, by reducing inhomogeneity when compared to ordinary polymer-based systems. Because the structure of this material gives us freedom to control the orientation of charge transport agents synthetically, we can study the charge transport mechanism more systematically than in polymers. We discuss this point and present the characterization results for this material.

Corrosion Behavior of Carbon Steel in Concrete Material Composed of Tin Slag Waste in Aqueous Chloride Solution

NASA Astrophysics Data System (ADS)

Rustandi, Andi; Cahyadi, Agung; Taruli Siallagan, Sonia; Wafa' Nawawi, Fuad; Pratesa, Yudha

2018-01-01

Tin slag is a byproduct of tin ore smelting process which is rarely utilized. The main purpose of this work is to investigate the use of tin slag for concrete cement material application compared to the industrial Ordinary Portland Cement (OPC). Tin slag composition was characterized by XRD and XRF analysis. The characterization results showed the similar chemical composition of tin slag and OPC. It also revealed the semi crystalline structure of tin slag sample. Several electrochemical tests were performed to evaluate corrosion behavior of tin slag, OPC and various mixed composition of both materials and the addition of CaO. The corrosion behavior of OPC and tin slag were evaluated by using Cyclic Polarization, Electrochemical Impedance Spectroscopy (EIS) and Electrochemical Frequency Modulation (EFM) methods. Aqueous sodium chloride (NaCl) solution with 3.5% w.t concentration which similar to seawater was used as the electrolyte in this work. The steel specimen used as the reinforce bar (rebar) material of the concrete was carbon steel AISI 1045. The rebar was embedded in the concrete cement which composed of OPC and the various composition of tin slag including slag without addition of CaO and slag mixed with addition of 50 % CaO. The electrochemical tests results revealed that tin slag affected its corrosion behavior which becoming more active and increasing the corrosion rate as well as decreasing the electrochemical impedance.

Method of making metal matrix composites reinforced with ceramic particulates

DOEpatents

Cornie, James A.; Kattamis, Theodoulos; Chambers, Brent V.; Bond, Bruce E.; Varela, Raul H.

1989-01-01

Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys.

Method of making metal matrix composites reinforced with ceramic particulates

DOEpatents

Cornie, J.A.; Kattamis, T.; Chambers, B.V.; Bond, B.E.; Varela, R.H.

1989-08-01

Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys. 2 figs.

Dependence of equivalent thermal conductivity coefficients of single-wall carbon nanotubes on their chirality

NASA Astrophysics Data System (ADS)

Zarubin, V. S.; Sergeeva, E. S.

2018-04-01

Composite materials (composites) composed of a matrix and reinforcing components are currently widely used as structural materials for various engineering devices designed to operate under extreme thermal and mechanical loads. By modifying a composite with structure-sensitive inclusions such as single-wall carbon nanotubes, one can significantly improve the thermomechanical properties of the resulting material. The paper presents relationships obtained for the equivalent thermal conductivity coefficients of single-wall carbon nanotubes versus their chirality using a simulation model developed to simulate the heat transfer process through thermal conductivity in a transversely isotropic environment. With these coefficients, one can conventionally substitute a single-wall carbon nanotube with a continuous anisotropic fiber, thus allowing one to estimate the thermal properties of composites reinforced with objects of this sort by using the well-known models developed for fibered composites. The results presented here can be used to estimate the thermal properties of carbon nanotube-reinforced composites.

Forming metal-intermetallic or metal-ceramic composites by self-propagating high-temperature reactions

DOEpatents

Rawers, James C.; Alman, David E.; Petty, Jr., Arthur V.

1996-01-01

Industrial applications of composites often require that the final product have a complex shape. In this invention intermetallic or ceramic phases are formed from sheets of unreacted elemental metals. The process described in this invention allows the final product shape be formed prior to the formation of the composite. This saves energy and allows formation of shaped articles of metal-intermetallic composites composed of brittle materials that cannot be deformed without breaking.

Preparation of Advanced CuO Nanowires/Functionalized Graphene Composite Anode Material for Lithium Ion Batteries

PubMed Central

Zhang, Jin; Wang, Beibei; Zhou, Jiachen; Xia, Ruoyu; Chu, Yingli; Huang, Jia

2017-01-01

The copper oxide (CuO) nanowires/functionalized graphene (f-graphene) composite material was successfully composed by a one-pot synthesis method. The f-graphene synthesized through the Birch reduction chemistry method was modified with functional group “–(CH2)5COOH”, and the CuO nanowires (NWs) were well dispersed in the f-graphene sheets. When used as anode materials in lithium-ion batteries, the composite exhibited good cyclic stability and decent specific capacity of 677 mA·h·g−1 after 50 cycles. CuO NWs can enhance the lithium-ion storage of the composites while the f-graphene effectively resists the volume expansion of the CuO NWs during the galvanostatic charge/discharge cyclic process, and provide a conductive paths for charge transportation. The good electrochemical performance of the synthesized CuO/f-graphene composite suggests great potential of the composite materials for lithium-ion batteries anodes. PMID:28772432

Achievement of a high-mobility FET with a cloud-aligned composite oxide semiconductor

NASA Astrophysics Data System (ADS)

Yamazaki, Shunpei; Shima, Yukinori; Hosaka, Yasuharu; Okazaki, Kenichi; Koezuka, Junichi

2016-11-01

We have recently discovered that films of a widely used In-Ga-Zn oxide (IGZO) with \\text{In}:\\text{Ga}:\\text{Zn} = 1:1:1 have different material composition states when sputter-deposited under different conditions using the same polycrystalline IGZO target. Significant improvements in on-state current and mobility (as high as 40 cm2·V-1·s-1) are obtained. The results of local composition analysis indicate that the deposited film is not composed of any known homogeneous IGZO compound and that the components of this film are separated into two types of nanoparticle regions: one type is composed mainly of GaO x and GaZnO x , which contribute to on/off (switching) characteristics, and the other is composed mainly of InO x and InZnO x , which contribute to on-state characteristics. These regions constitute a new type of oxide semiconductor (OS) film. The nanoparticles with a blurry boundary extend like a cloud, probably complementing one another. We consider that this OS film has a novel composition, which can be described as a “cloud-aligned composite OS” (CAC-OS).

"Greener" hybrid adhesives composed of urea formaldehyde resin and cottonseed meal for wood based composites

USDA-ARS?s Scientific Manuscript database

Urea formaldehyde (UF) resins are one of the most widely used adhesives in wood based composites. The major concerns of the resin utilization are free formaldehyde release and poor water resistance. As a renewable raw materials, water washed conttonseed meal can be used in wood bonding. To produce “...

Relationship of wood surface energy to surface composition

Treesearch

Feipeng P. Liu; Timothy G. Rials; John Simonsen

1998-01-01

The wood cell wall is composed of cellulose, lignin, hemicelluloses, and extractives. Thus, the surface energy of the wood material must be some combination of the surface energies of these components. The influence of extractives on wood surface chemistry can be important in diverse industrial applications, such as coating, pulping, and wood-based composites. In this...

Epoxy-borax-coal tar composition for a radiation protective, burn resistant drum liner and centrifugal casting method

DOEpatents

Taylor, Robert S.; Boyer, Norman W.

1980-01-01

A boron containing burn resistant, low level radiation protection material useful, for example, as a liner for radioactive waste disposal and storage, a component for neutron absorber, and a shield for a neutron source. The material is basically composed of Borax in the range of 25-50%, coal tar in the range of 25-37.5%, with the remainder being an epoxy resin mix. A preferred composition is 50% Borax, 25% coal tar and 25% epoxy resin. The material is not susceptible to burning and is about 1/5 the cost of existing radiation protection material utilized in similar applications.

Epoxy-borax-coal tar composition for a radiation protective, burn resistant drum liner and centrifugal casting method

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

Boyer, N.W.; Taylor, R.S.

1980-10-28

A boron containing burn resistant, low level radiation protection material useful, for example, as a liner for radioactive waste disposal and storage, a component for neutron absorber, and a shield for a neutron source. The material is basically composed of borax in the range of 25-50%, coal tar in the range of 25-37.5%, with the remainder being an epoxy resin mix. A preferred composition is 50% borax, 25% coal tar and 25% epoxy resin. The material is not susceptible to burning and is about 1/5 the cost of existing radiation protection material utilized in similar applications.

Heavily loaded ferrite-polymer composites to produce high refractive index materials at centimetre wavelengths

NASA Astrophysics Data System (ADS)

Parke, L.; Hooper, I. R.; Hicken, R. J.; Dancer, C. E. J.; Grant, P. S.; Youngs, I. J.; Sambles, J. R.; Hibbins, A. P.

2013-10-01

A cold-pressing technique has been developed for fabricating composites composed of a polytetrafluoroethylene-polymer matrix and a wide range of volume-fractions of MnZn-ferrite filler (0%-80%). The electromagnetic properties at centimetre wavelengths of all prepared composites exhibited good reproducibility, with the most heavily loaded composites possessing simultaneously high permittivity (180 ± 10) and permeability (23 ± 2). The natural logarithm of both the relative complex permittivity and permeability shows an approximately linear dependence with the volume fraction of ferrite. Thus, this simple method allows for the manufacture of bespoke materials required in the design and construction of devices based on the principles of transformation optics.

Nonhazardous solvent composition and method for cleaning metal surfaces

DOEpatents

Googin, John M.; Simandl, Ronald F.; Thompson, Lisa M.

1993-01-01

A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140.degree. F. and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140.degree. F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

Nonhazardous solvent composition and method for cleaning metal surfaces

DOEpatents

Googin, J.M.; Simandl, R.F.; Thompson, L.M.

1993-05-04

A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140 F and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140 F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

Equations of State and High-Pressure Phases of Explosives

NASA Astrophysics Data System (ADS)

Peiris, Suhithi M.; Gump, Jared C.

Energetic materials, being the collective name for explosives, propellants, pyrotechnics, and other flash-bang materials, span a wide range of composite chemical formulations. Most militarily used energetics are solids composed of particles of the pure energetic material held together by a binder. Commonly used binders include various oils, waxes, and polymers or plasticizers, and the composite is melt cast, cured, or pressed to achieve the necessary mechanical properties (gels, putties, sheets, solid blocks, etc.) of the final energetic material. Mining, demolition, and other industries use liquid energetics that are similarly composed of an actual energetic material or oxidizer together with a fuel, that is to be mixed and poured for detonation. Pure energetic materials that are commonly used are nitroglycerine, ammonium nitrate, ammonium or sodium perchlorate, trinitrotoluene (TNT), HMX, RDX, and TATB. All of them are molecular materials or molecular ions that when initiated or insulted undergoes rapid decomposition with excessive liberation of heat resulting in the formation of stable final products. When the final products are gases, and they are rapidly produced, the sudden pressure increase creates a shock wave. When decomposition is so rapid that the reaction moves through the explosive faster than the speed of sound in the unreacted explosive, the material is said to detonate. Typically, energetic materials that undergo detonation are known as high explosives (HEs) and energetic materials that burn rapidly or deflagrate are known as low explosives and/or propellants.

Graphite intercalated polyaniline composite with superior anticorrosive and hydrophobic properties, as protective coating material on steel surfaces

NASA Astrophysics Data System (ADS)

Rathnayake, R. M. N. M.; Mantilaka, M. M. M. G. P. G.; Hara, Masanori; Huang, Hsin-Hui; Wijayasinghe, H. W. M. A. C.; Yoshimura, Masamichi; Pitawala, H. M. T. G. A.

2017-07-01

Solid polymer composite systems are widely being used for potential technological applications in secondary energy sources and electrochromic devices. In this study, we synthesized and characterized a composite material composed of polyaniline (PANI) and natural needle platy (NPG) vein graphite. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), micro-Raman analysis, thermogravimetric and differential thermal analysis (TGA/DTA), transmission electron microscopy (TEM) were used to study the structural and electrochemical properties of the prepared PANI/NPG graphite composite. XPS, FTIR, and micro-Raman analysis confirmed the existence of relevant functional groups and bonding in the prepared PANI/NPG composite material. The composite shows a very low corrosion rate, approximately 29 μm per year, and high hydrophobicity on steel surfaces, which helps to prevent the corrosion due to O2 penetration towards the metal surface. It indicates that the composite can be used as a high potential surface coating material to anticorrosion. The specific capacitance of PANI/NPG composite is 833.3 F g-1, which is higher than that of PANI. This synergistic electrical performance result proves the prepared PANI/NPG graphite composite as a suitable protective coating material for steel surfaces.

Band gap structures for 2D phononic crystals with composite scatterer

NASA Astrophysics Data System (ADS)

Qi, Xiao-qiao; Li, Tuan-jie; Zhang, Jia-long; Zhang, Zhen; Tang, Ya-qiong

2018-05-01

We investigated the band gap structures in two-dimensional phononic crystals with composite scatterer. The composite scatterers are composed of two materials (Bragg scattering type) or three materials (locally resonance type). The finite element method is used to calculate the band gap structure, eigenmodes and transmission spectrum. The variation of the location and width of band gap are also investigated as a function of material ratio in the scatterer. We have found that the change trends the widest band gap of the two phononic crystals are different as the material ratio changing. In addition to this, there are three complete band gaps at most for the Bragg-scattering-type phononic crystals in the first six bands; however, the locally resonance-type phononic crystals exist only two complete band gap at most in the first six bands. The gap-tuning effect can be controlled by the material ratio in the scatterer.

Analysis of a new composite material for watercraft manufacturing

NASA Astrophysics Data System (ADS)

Wahrhaftig, Alexandre; Ribeiro, Henrique; Nascimento, Ademar; Filho, Milton

2016-09-01

In this paper, we investigate the properties of an alternative material for use in marine engineering, namely a rigid and light sandwich-structured composite made of expanded polystyrene and fiberglass. Not only does this material have an improved section modulus, but it is also inexpensive, light, easy to manipulate, and commercially available in various sizes. Using a computer program based on the finite element method, we calculated the hogging and sagging stresses and strains acting on a prismatic boat model composed of this material, and determined the minimum sizes and maximum permissible stresses to avoid deformation. Finally, we calculated the structural weight of the resulting vessel for comparison with another structure of comparable dimensions constructed from the commonly used core material Divinycell.

Brittle behavior of ceramic matrix composites made of 2 different phases

NASA Astrophysics Data System (ADS)

Sadowski, Tomasz; Craciun, Eduard; Marsavina, Liviu

2018-02-01

Brittle behavior of Ceramic matrix Composites (CMCs) results from overall response to applied loads due to complex of their internal microstructure. The CMCs materials are composed of mixtures of phases, some amount of porosity and technological defects. The phases can exhibit purely elastic behavior or elastic-plastic one under high level of loading. The crucial point in description of their behavior is correlation of microcracking processes with the type of loading, i.e. tensile or compressive. This distinction in the material behavior is typical for so called brittle materials. In this paper we compared both microcracking processes for the above 2 characteristic loading paths.

Workshop on the Design and Processing of Materials by Biomimicking Held in Seattle, Washington on 2-4 April 1991

DTIC Science & Technology

1991-11-01

These materials feature repeating stem-turn elements composed of 1-strands and amino acids predicted to participate in 1-hairpin formation. The...highly ordered crystalline material. Presently we are studying: (i) the effects of amino acid sequence on 1-turn formation, (ii) the influence of stem...length and amino acid composition on chain folding and materials properties, and (iii) the potential for biological incorporation of unnatural amino

Metal Nanoparticles Covered with a Metal-Organic Framework: From One-Pot Synthetic Methods to Synergistic Energy Storage and Conversion Functions.

PubMed

Kobayashi, Hirokazu; Mitsuka, Yuko; Kitagawa, Hiroshi

2016-08-01

Hybrid materials composed of metal nanoparticles and metal-organic frameworks (MOFs) have attracted much attention in many applications, such as enhanced gas storage and catalytic, magnetic, and optical properties, because of the synergetic effects between the metal nanoparticles and MOFs. In this Forum Article, we describe our recent progress on novel synthetic methods to produce metal nanoparticles covered with a MOF (metal@MOF). We first present Pd@copper(II) 1,3,5-benzenetricarboxylate (HKUST-1) as a novel hydrogen-storage material. The HKUST-1 coating on Pd nanocrystals results in a remarkably enhanced hydrogen-storage capacity and speed in the Pd nanocrystals, originating from charge transfer from Pd nanocrystals to HKUST-1. Another material, Pd-Au@Zn(MeIM)2 (ZIF-8, where HMeIM = 2-methylimidazole), exhibits much different catalytic activity for alcohol oxidation compared with Pd-Au nanoparticles, indicating a design guideline for the development of composite catalysts with high selectivity. A composite material composed of Cu nanoparticles and Cr3F(H2O)2O{C6H3(CO2)3}2 (MIL-100-Cr) demonstrates higher catalytic activity for CO2 reduction into methanol than Cu/γ-Al2O3. We also present novel one-pot synthetic methods to produce composite materials including Pd/ZIF-8 and Ni@Ni2(dhtp) (MOF-74, where H4dhtp = 2,5-dihydroxyterephthalic acid).

Layer Structure of a Refractory Multilayer Ti/Al Composite After Pressure Diffusion Welding

NASA Astrophysics Data System (ADS)

Karpov, M. I.; Korzhov, V. P.; Zheltyakova, I. S.

2016-05-01

A composite refractory material with layer structure obtained by the method of pressure diffusion welding of multilayer Ti/Al packets composed of Ti- and Al-foils is studied. The welding temperature of the packets does not exceed 1200 - 1250°C. A layer structure forms in the process of interdiffusion of titanium and aluminum during welding of the packets.

Alloy and method of producing the same

DOEpatents

Hufnagel, Todd C.; Ott, Ryan T.; Fan, Cang; Kecskes, Laszlo

2005-07-19

In accordance with a preferred embodiment of the invention, an alloy or other composite material is provided formed of a bulk metallic glass matrix with a microstructure of crystalline metal particles. The alloy preferably has a composition of (X.sub.a Ni.sub.b Cu.sub.c).sub.100-d-c Y.sub.d Al.sub.c, wherein the sum of a, b and c equals 100, wherein 40.ltoreq.a.ltoreq.80, 0.ltoreq.b.ltoreq.35, 0.ltoreq.c.ltoreq.40, 4.ltoreq.d.ltoreq.30, and 0.ltoreq.e.ltoreq.20, and wherein preferably X is composed of an early transition metal and preferably Y is composed of a refractory body-centered cubic early transition metal. A preferred embodiment of the invention also provides a method of producing an alloy composed of two or more phases at ambient temperature. The method includes the steps of providing a metastable crystalline phase composed of at least two elements, heating the metastable crystalline phase together with at least one additional element to form a liquid, casting the liquid, and cooling the liquid to form the alloy. In accordance with a preferred embodiment of the invention, the composition and cooling rate of the liquid can be controlled to determine the volume fraction of the crystalline phase and determine the size of the crystalline particles, respectively.

Process to produce lithium-polymer batteries

DOEpatents

MacFadden, Kenneth Orville

1998-01-01

A polymer bonded sheet product suitable for use as an electrode in a non-aqueous battery system. A porous electrode sheet is impregnated with a solid polymer electrolyte, so as to diffuse into the pores of the electrode. The composite is allowed to cool, and the electrolyte is entrapped in the porous electrode. The sheet products composed have the solid polymer electrolyte composition diffused into the active electrode material by melt-application of the solid polymer electrolyte composition into the porous electrode material sheet. The solid polymer electrolyte is maintained at a temperature that allows for rapid diffusion into the pores of the electrode. The composite electrolyte-electrode sheets are formed on current collectors and can be coated with solid polymer electrolyte prior to battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte coating has low resistance.

Research on self-propagating high temperature synthesis prepared ZrC-ZrB2 composite ceramic

NASA Astrophysics Data System (ADS)

Yong, Cheng; Xunjia, Su; Genliang, Hou; YaKun, Xing

2013-03-01

ZrC-ZrB2 composite ceramic material is prepared by self-propagating high temperature synthesis, using Zr powders, CrO2 powders and Al powders as raw materials. Samples are studied by XRD and SEM, the results show that: ZrC-ZrB2 composite ceramic is attained after self-propagating high-temperature reaction, with Zr+ B4C as the main reactive system, and which is added respectively different content (CrO3 + Al) system. The study finds that the ceramic composite products are mainly composed of ZrC and ZrB2 phase, and other subphase. Compared to the main reactive system composite ceramic, composite ceramic grains grow up obviously, after introduction of the highly exothermic system (CrO3 + Al) in the main reactive system, and with the gradual increase of the content (CrO3 + Al).

Construction of physical crosslink-based chitosan/liquid crystal composite hydrogel and evaluation on their cytocompatibility

PubMed Central

Du, Lin; Yang, Xiaohui; Li, Wenqiang; Luo, Xuhui; Wu, Hao; Zhang, Jiaqing; Tu, Mei

2017-01-01

In order to provide a novel biomimetic composite substrate for tissue engineering and explore the interaction between cells and this type of material, we developed chitosan/liquid crystal (CS/LC) composite hydrogel with embedded LC phases by composing of cholesterol hydroxypropyl cellulose ester liquid crystalline material and CS. The micromorphology of CS/LC composite hydrogels exhibited ‘islands-sea’ phase separation structures similar to the ‘fluid mosaic model’ of biomembrane. In vitro cell compatibility study suggested that 3T3 is fibroblasts exhibited better initial cell adhesions and higher proliferation rates on the composite hydrogel than on the polystyrene control plate and the pure LC membrane. This novel CS/LC composite hydrogel provides more favorable interface for cell growth and proliferation and may serve as potentially active substrate for engineering interfaces to live cells. PMID:28149528

Bio-composites composed of a solid free-form fabricated polycaprolactone and alginate-releasing bone morphogenic protein and bone formation peptide for bone tissue regeneration.

PubMed

Kim, MinSung; Jung, Won-Kyo; Kim, GeunHyung

2013-11-01

Biomedical scaffolds should be designed with highly porous three-dimensional (3D) structures that have mechanical properties similar to the replaced tissue, biocompatible properties, and biodegradability. Here, we propose a new composite composed of solid free-form fabricated polycaprolactone (PCL), bone morphogenic protein (BMP-2) or bone formation peptide (BFP-1), and alginate for bone tissue regeneration. In this study, PCL was used as a mechanical supporting component to enhance the mechanical properties of the final biocomposite and alginate was used as the deterring material to control the release of BMP-2 and BFP-1. A release test revealed that alginate can act as a good release control material. The in vitro biocompatibilities of the composites were examined using osteoblast-like cells (MG63) and the alkaline phosphatase (ALP) activity and calcium deposition were assessed. The in vitro test results revealed that PCL/BFP-1/Alginate had significantly higher ALP activity and calcium deposition than the PCL/BMP-2/Alginate composite. Based on these findings, release-controlled BFP-1 could be a good growth factor for enhancement of bone tissue growth and the simple-alginate coating method will be a useful tool for fabrication of highly functional biomaterials through release-control supplementation.

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

Liu, Tingting; Northeast Petroleum University at Qinhuangdao, Qinhuangdao 066004; Shao, Guangjie, E-mail: shaoguangjie@ysu.edu.cn

A method of pulse electrodeposition under supergravity field was proposed to synthesize MnO{sub 2}-graphene composites. Supergravity is very efficient for promoting mass transfer and decreasing concentration polarization during the electrodeposition process. The synthesis was conducted on our homemade supergravity equipment. The strength of supergravity field depended on the rotating speed of the ring electrode. 3D flower like MnO{sub 2} spheres composed of nanoflakes were acquired when the rotating speed was 3000 rpm. Graphene nanosheets play as a role of conductive substrates for MnO{sub 2} growing. The composites are evaluated as electrode materials for supercapacitors. Electrochemical results show that the maximummore » specific capacitance of the MnO{sub 2}-graphene composite is 595.7 F g{sup −1} at a current density of 0.5 A g{sup −1}. In addition, the composite exhibits excellent cycle stability with no capacitance attenuation after 1000 cycles. The approach provides new ideas for developing supercapacitor electrode materials with high performance. - Graphical abstract: 3D flower like MnO{sub 2} spheres composed of nanoflakes were acquired at 3000 rpm. - Highlights: • MnO{sub 2}-graphene composites were prepared by pulse electrodeposition under supergravity. • 3D flower like MnO{sub 2} spheres are anchored on the graphene nanosheets. • The MnO{sub 2}-graphene electrode exhibits a specific capacitance of 595.7 F g{sup −1}.« less

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

Modak, Partha; Hossain, M. Jamil, E-mail: jamil917@gmail.com; Ahmed, S. Reaz

An accurate stress analysis has been carried out to investigate the suitability of a hybrid balanced laminate as a structural material for thick composite beams with axial stiffeners. Three different balanced laminates composed of dissimilar ply material as well as fiber orientations are considered for a thick beam on simple supports with stiffened lateral ends. A displacement potential based elasticity approach is used to obtain the numerical solution of the corresponding elastic fields. The overall laminate stresses as well as individual ply stresses are analysed mainly in the perspective of laminate hybridization. Both the fiber material and ply angle ofmore » individual laminas are found to play dominant roles in defining the design stresses of the present composite beam.« less

ITO/gold nanoparticle/RGD peptide composites to enhance electrochemical signals and proliferation of human neural stem cells.

PubMed

Kim, Tae-Hyung; El-Said, Waleed Ahmed; An, Jeung Hee; Choi, Jeong-Woo

2013-04-01

A cell chip composed of ITO, gold nanoparticles (GNP) and RGD-MAP-C peptide composites was fabricated to enhance the electrochemical signals and proliferation of undifferentiated human neural stem cells (HB1.F3). The structural characteristics of the fabricated surfaces were confirmed by both scanning electron microscopy and surface-enhanced Raman spectroscopy. HB1.F3 cells were allowed to attach to various composites electrodes in the cell chip and the material-dependent effects on electrochemical signals and cell proliferation were analyzed. The ITO/60 nm GNP/RGD-MAP-C composite electrode was found to be the best material in regards to enhancing the voltammetric signals of HB1.F3 cells when exposed to cyclic voltammetry, as well as for increasing cell proliferation. Differential pulse voltammetry was performed to evaluate the adverse effects of doxorubicin on HB1.F3 cells. In these experiments, negative correlations between cell viability and chemical concentrations were obseved, which were more sensitive than MTT viability assay especially at low concentrations (<0.1 μg/mL). In this basic science study, a cell chip composed of ITO, gold nanoparticles and RGD-MAP-C peptide composites was fabricated to enhance electrochemical signals and proliferation of undifferentiated human neural stem cells (HB1.F3). The ITO/60 nm GNP/RGD-MAP-C composite electrode was found to best enhance the voltammetric signals of the studied cells. Copyright © 2013 Elsevier Inc. All rights reserved.

Metal Oxide Materials and Collector Efficiency in Electrochemical Supercapacitors

DTIC Science & Technology

2010-12-01

However, even if thick tita - nium films and/or nanostructured layers were obtained using these methods, they were composed of non-conducting titanium...following electrochemical reduction in LiClO4/acetonitrile. Table 1 reports the electrochemical parameters and the atomic composition of the tita - nium

Process to produce lithium-polymer batteries

DOEpatents

MacFadden, K.O.

1998-06-30

A polymer bonded sheet product is described suitable for use as an electrode in a non-aqueous battery system. A porous electrode sheet is impregnated with a solid polymer electrolyte, so as to diffuse into the pores of the electrode. The composite is allowed to cool, and the electrolyte is entrapped in the porous electrode. The sheet products composed have the solid polymer electrolyte composition diffused into the active electrode material by melt-application of the solid polymer electrolyte composition into the porous electrode material sheet. The solid polymer electrolyte is maintained at a temperature that allows for rapid diffusion into the pores of the electrode. The composite electrolyte-electrode sheets are formed on current collectors and can be coated with solid polymer electrolyte prior to battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte coating has low resistance. 1 fig.

Metal oxide composite enabled nanotextured Si photoanode for efficient solar driven water oxidation.

PubMed

Sun, Ke; Pang, Xiaolu; Shen, Shaohua; Qian, Xueqiang; Cheung, Justin S; Wang, Deli

2013-05-08

We present a study of a transition metal oxide composite modified n-Si photoanode for efficient and stable water oxidation. This sputter-coated composite functions as a protective coating to prevent Si from photodecomposition, a Schottky heterojunction, a hole conducting layer for efficient charge separation and transportation, and an electrocatalyst to reduce the reaction overpotential. The formation of mixed-valence oxides composed of Ni and Ru effectively modifies the optical, electrical, and catalytic properties of the coating material, as well as the interfaces with Si. The successful application of this oxide composite on nanotextured Si demonstrates improved conversion efficiency due to enhanced catalytic activity, minimized reflection, and increased surface reaction sites. Although the coated nanotextured Si shows a noticeable degradation from 500 cycles of operation, the oxide composite provides a simple method to enable unstable photoanode materials for solar fuel conversion.

Ternary Polymeric Composites Exhibiting Bulk and Surface Quadruple-Shape Memory Properties.

PubMed

Buffington, Shelby Lois; Posnick, Benjamin M; Paul, Justine Elizabeth; Mather, Patrick T

2018-06-19

We report the design and characterization of a multiphase quadruple shape memory composite capable of switching between 4 programmed shapes, three temporary and one permanent. Our approach combined two previously reported fabrication methods by embedding an electrospun mat of PCL in a miscible blend of epoxy monomers and PMMA as a composite matrix. As epoxy polymerization occurred the matrix underwent phase separation between the epoxy and PMMA materials. This created a multiphase composite with PCL fibers and a two-phase matrix composed of phase-separated epoxy and PMMA. The resulting composite demonstrated three separate thermal transitions and amenability to mechanical programming of three separate temporary shapes in addition to one final, equilibrium shape. In addition, quadruple surface shape memory abilities are successfully demonstrated. The versatility of this approach offers a large degree of design flexibility for multi-shape memory materials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flame spread behavior over combustible thick solid of paper, bagasse and mixed paper/bagasse

NASA Astrophysics Data System (ADS)

Azahari Razali, Mohd; Mohd, Sofian; Sapit, Azwan; Nizam Mohammed, Akmal; Husaini Ismail, Ahmad; Faisal Hushim, Mohd; Jaat, Norrizam; Khalid, Amir

2017-09-01

Flame spread behavior on combustible solid is one of important research related to Fire Safety Engineering. Now, there are a lot of combustible solid composed from mixed materials. In this study, experiments have been conducted to investigate flame spread behavior over combustible solid composed by paper, bagasse and mixed paper/bagasse. Experimental data is captured by using video recording and examined flame spread shape and rate. From the results obtained, shows that the different materials produce different flame spread shape and rate. Different flame shape is seen between all types of samples. Flame spread rate of 100% paper is faster than the one of 100% bagasse. Based on the result, it is also inferred that the material composition can be influenced on the flame spread shape and flame spread rate of mixed paper/bagasse.

Gas adsorption capacity in an all carbon nanomaterial composed of carbon nanohorns and vertically aligned carbon nanotubes.

PubMed

Puthusseri, Divya; Babu, Deepu J; Okeil, Sherif; Schneider, Jörg J

2017-10-04

Whereas vertically aligned carbon nanotubes (VACNTs) typically show a promising adsorption behavior at high pressures, carbon nanohorns (CNHs) exhibit superior gas adsorption properties in the low pressure regime due to their inherent microporosity. These adsorption characteristics are further enhanced when both materials are opened at their tips. The so prepared composite material allows one to investigate the effect of physical entrapment of CO 2 molecules within the specific adsorption sites of VACNTs composed of opened double walled carbon nanotubes (CNTs) and in specific adsorption sites created by spherically aggregated opened single walled carbon nanohorns. Combining 50 wt% of tip opened CNTs with tip opened CNHs increases the CO 2 adsorption capacity of this material by ∼24% at 30 bar and 298 K compared to opened CNHs alone.

Review of progress in quantitative NDE. [Nondestructive Evaluation (NDE)

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

Not Available

1991-01-01

This booklet is composed of abstracts from papers submitted at a meeting on quantitative NDE. A multitude of topics are discussed including analysis of composite materials, NMR uses, x-ray instruments and techniques, manufacturing uses, neural networks, eddy currents, stress measurements, magnetic materials, adhesive bonds, signal processing, NDE of mechanical structures, tomography,defect sizing, NDE of plastics and ceramics, new techniques, optical and electromagnetic techniques, and nonlinear techniques. (GHH)

Biomimetic, Strong, Tough, and Self-Healing Composites Using Universal Sealant-Loaded, Porous Building Blocks.

PubMed

Hwang, Sung Hoon; Miller, Joseph B; Shahsavari, Rouzbeh

2017-10-25

Many natural materials, such as nacre and dentin, exhibit multifunctional mechanical properties via structural interplay between compliant and stiff constituents arranged in a particular architecture. Herein, we present, for the first time, the bottom-up synthesis and design of strong, tough, and self-healing composite using simple but universal spherical building blocks. Our composite system is composed of calcium silicate porous nanoparticles with unprecedented monodispersity over particle size, particle shape, and pore size, which facilitate effective loading and unloading with organic sealants, resulting in 258% and 307% increases in the indentation hardness and elastic modulus of the compacted composite. Furthermore, heating the damaged composite triggers the controlled release of the nanoconfined sealant into the surrounding area, enabling moderate recovery in strength and toughness. This work paves the path towards fabricating a novel class of biomimetic composites using low-cost spherical building blocks, potentially impacting bone-tissue engineering, insulation, refractory and constructions materials, and ceramic matrix composites.

Method for making an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.; Pal, Uday B.

1996-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is provided.

Penalty-Based Finite Element Interface Technology for Analysis of Homogeneous and Composite Structures

NASA Technical Reports Server (NTRS)

Averill, Ronald C.

2002-01-01

An effective and robust interface element technology able to connect independently modeled finite element subdomains has been developed. This method is based on the use of penalty constraints and allows coupling of finite element models whose nodes do not coincide along their common interface. Additionally, the present formulation leads to a computational approach that is very efficient and completely compatible with existing commercial software. A significant effort has been directed toward identifying those model characteristics (element geometric properties, material properties, and loads) that most strongly affect the required penalty parameter, and subsequently to developing simple 'formulae' for automatically calculating the proper penalty parameter for each interface constraint. This task is especially critical in composite materials and structures, where adjacent sub-regions may be composed of significantly different materials or laminates. This approach has been validated by investigating a variety of two-dimensional problems, including composite laminates.

NDE for Material Characterization in Aeronautic and Space Applications

NASA Technical Reports Server (NTRS)

Baaklini, George Y.; Kautz, Harold E.; Gyekenyesi, Andrew L.; Abdul-Aziz, Ali; Martin, Richard E.

2000-01-01

This paper describes selected nondestructive evaluation (NDE) approaches that were developed or tailored at the NASA Glenn Research Center for characterizing advanced material systems. The emphasis is on high-temperature aerospace propulsion applications. The material systems include monolithic ceramics, superalloys, and high temperature composites. In the aeronautic area, the highlights are cooled ceramic plate structures for turbine applications, F-TiAl blade materials for low-pressure turbines, thermoelastic stress analysis (TSA) for residual stress measurements in titanium based and nickel based engine materials, and acousto ultrasonics (AU) for creep damage assessment in nickel-based alloys. In the space area, examples consist of cooled carbon-carbon composites for gas generator combustors and flywheel rotors composed of carbon fiber reinforced polymer matrix composites for energy storage on the international space station (ISS). The role of NDE in solving manufacturing problems, the effect of defects on structural behavior, and the use of NDE-based finite element modeling are discussed. NDE technology needs for improved microelectronic and mechanical systems as well as health monitoring of micro-materials and components are briefly discussed.

Fascinating Magnetic Energy Storage Nanomaterials: A Brief Review.

PubMed

Sreenivasulu, Kummari V; Srikanth, Vadali V S S

2017-07-10

In this brief review, the importance of nanotechnology in developing novel magnetic energy storage materials is discussed. The discussion covers recent patents on permanent magnetic materials and especially covers processing of permanent magnets (rare-earth and rare-earth free magnets), importance of rare-earth permanent magnets and necessity of rare-earth free permanent magnets. Magnetic energy storage materials are those magnetic materials which exhibit very high energy product (BH)max (where B is the magnetic induction in Gauss (G) whereas H is the applied magnetic field in Oersted (Oe)). (BH)max is the direct measure of the ability of a magnetic material to store energy. In this context, processing of magnetic energy storage composite materials constituted by soft and hard magnetic materials played a predominant role in achieving high (BH)max values due to the exchange coupling phenomenon between the soft and hard magnetic phases within the composite. Magnetic energy storage composites are normally composed of rare-earth magnetic materials as well as rare-earth free magnetic materials. Nanotechnology's influence on the enhancement of energy product due to the exchange coupling phenomenon is of great prominence and therefore discussed in this review. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

UMAT Implementation of Coupled, Multilevel, Structural Deformation and Damage Analysis of General Hereditary Materials

NASA Technical Reports Server (NTRS)

Arnold, S. M.; Saleeb, A. F.; Wilt, T. E.; Trowbridge, D.

2000-01-01

Extensive research efforts have been made over the years on the phenomenological representations of constitutive material behavior in the inelastic analysis and life assessment of structures composed of advanced monolithic and composite (CMC, MMC, and PMC) materials. Recently, emphasis has been placed on concurrently addressing three important and related areas of constitutive and degradation modeling; i.e. (i) mathematical formulation, (ii) algorithmic developments for the updating (integrating) of external (e.g. stress) and internal state variable, as well as (iii) parameter estimation for the characterization of the specific model. This concurrent perspective has resulted in; i) the formulation of a fully-associative viscoelastoplastic model (GVIPS), (ii) development of an efficient implicit integration and it's associative, symmetric, consistent tangent stiffness matrix algorithm for integration of the underlying rate flow/evolutionary equations, and iii) a robust, stand-alone, Constitutive Material Parameter Estimator (COMPARE) for automatically characterizing the various time-dependent, nonlinear, material models. Furthermore, to provide a robust multi-scale framework for the deformation and life analysis of structures composed of composite materials, NASA Glenn has aggressively pursued the development of a sufficiently general, accurate, and efficient micromechanics approach known as the generalized method of cells (GMC). This work has resulted in the development of MAC/GMC, a stand-alone micromechanics analysis tool that can easily and accurately design/analyze multiphase (composite) materials subjected to complex histories. MAC/GMC admits generalized, physically based, deformation and damage models for each constituent and provides "closed-form" expressions for the macroscopic composite response in terms of the properties, size, shape, distribution, and response of the individual constituents or phases that comprise the material. Consequently, MAC/GMC can be incorporated directly into a structural finite element code like ABAQUS for cost-effective, micromechanics based, large-scale component design and analysis. Our primary objective here is to report on these recent works conducted over the past decade, in the context of their incorporation into ABAQUS through the various user subroutines. Representative results will be shown to demonstrate the features of the developed schemes.

Material for radioactive protection

DOEpatents

Taylor, R.S.; Boyer, N.W.

A boron containing burn resistant, low-level radiation protection material useful, for example, as a liner for radioactive waste disposal and storage, a component for neutron absorber, and a shield for a neutron source is described. The material is basically composed of borax in the range of 25 to 50%, coal tar in the range of 25 to 37.5%, with the remainder being an epoxy resin mix. A preferred composition is 50% borax, 25% coal tar and 25% epoxy resin. The material is not susceptible to burning and is about 1/5 the cost of existing radiation protection material utilized in similar applications.

Design strategies and applications of nacre-based biomaterials.

PubMed

Gerhard, Ethan Michael; Wang, Wei; Li, Caiyan; Guo, Jinshan; Ozbolat, Ibrahim Tarik; Rahn, Kevin Michael; Armstrong, April Dawn; Xia, Jingfen; Qian, Guoying; Yang, Jian

2017-05-01

The field of tissue engineering and regenerative medicine relies heavily on materials capable of implantation without significant foreign body reactions and with the ability to promote tissue differentiation and regeneration. The field of bone tissue engineering in particular requires materials capable of providing enhanced mechanical properties and promoting osteogenic cell lineage commitment. While bone repair has long relied almost exclusively on inorganic, calcium phosphate ceramics such as hydroxyapatite and their composites or on non-degradable metals, the organically derived shell and pearl nacre generated by mollusks has emerged as a promising alternative. Nacre is a naturally occurring composite material composed of inorganic, calcium carbonate plates connected by a framework of organic molecules. Similar to mammalian bone, the highly organized microstructure of nacre endows the composite with superior mechanical properties while the organic phase contributes to significant bioactivity. Studies, both in vitro and in vivo, have demonstrated nacre's biocompatibility, biodegradability, and osteogenic potential, which are superior to pure inorganic minerals such as hydroxyapatite or non-degradable metals. Nacre can be used directly as a bulk implant or as part of a composite material when combined with polymers or other ceramics. While nacre has demonstrated its effectiveness in multiple cell culture and animal models, it remains a relatively underexplored biomaterial. This review introduces the formation, structure, and characteristics of nacre, and discusses the present and future uses of this biologically-derived material as a novel biomaterial for orthopedic and other tissue engineering applications. Mussel derived nacre, a biological composite composed of mineralized calcium carbonate platelets and interplatelet protein components, has recently gained interest as a potential alternative ceramic material in orthopedic biomaterials, combining the integration and mechanical capabilities of calcium phosphates with increased bioactivity derived from proteins and biomolecules; however, there is limited awareness of this material's potential. Herein, we present, to our knowledge, the first comprehensive review of nacre as a biomaterial. Nacre is a highly promising yet overlooked biomaterial for orthopedic tissue engineering with great potential in a wide variety of material systems. It is our hope that publication of this article will lead to increased community awareness of the potential of nacre as a versatile, bioactive ceramic capable of improving bone tissue regeneration and will elicit increased research effort and innovation utilizing nacre. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Healing efficiency of epoxy-based materials for structural application

NASA Astrophysics Data System (ADS)

Raimondo, Marialuigia; Guadagno, Liberata

2012-07-01

This paper describes a self-healing composite exhibiting high levels of healing efficiency under working conditions typical of aeronautic applications. The self-healing material is composed of a thermosetting epoxy matrix in which a catalyst of Ring Opening Metathesis Polymerization (ROMP) and nanocapsules are dispersed. The nanocapsules contain a monomer able to polymerize via ROMP. The preliminary results demonstrate an efficient self-repair function which is also active at very low temperatures.

Electrostatic Discharge Testing of Carbon Composite Solar Array Panels for Use in the Jovian Environment

NASA Technical Reports Server (NTRS)

Green, Nelson W.; Dawson, Stephen F.

2015-01-01

NASA is currently considering a mission to investigate the moons of Jupiter. When designing a spacecraft for this type of mission, there are a number of engineering challenges, especially if the mission chooses to utilize solar arrays to provide the spacecraft power. In order for solar arrays to be feasible for the mission, their total mass needed to fit within the total budget for the mission, which strongly suggested the use of carbon composite facesheets on an aluminum core for the panel structure. While these composite structures are a good functional substitution for the metallic materials they replace, they present unique challenges when interacting with the harsh Jovian space environment. As a composite material, they are composed of more than one material and can show different base properties depending in differing conditions. Looking at the electrical properties, in an Earth-based environment the carbon component of the composite dominates the response of the material to external stimulus. Under these conditions, the structures strongly resembles a conductor. In the Jovian environment, with temperatures reaching 50K and under the bombardment from energetic electrons, the non-conducting pre-preg binding materials may come to the forefront and change the perceived response. Before selecting solar arrays as the baseline power source for a mission to Jupiter, the response of the carbon composites to energetic electrons while held at cryogenic temperatures needed to be determined. A series of tests were devised to exam the response of a sample solar array panel composed of an M55J carbon weave layup with an RS-3 pre-preg binder. Test coupons were fabricated and exposed to electrons ranging from 10 keV to 100 keV, at 1 nA/cm2, while being held at cryogenic temperatures. While under electron bombardment, electrical discharges were observed and recorded with the majority of discharges occurring with electron energies of 25 keV. A decrease in temperature to liquid nitrogen temperatures showed a marked increase in the magnitude of these discharges. The results indicate that dielectric discharges are primarily produced due to the presence of large regions of the non-conductive pre-preg on the surface of the carbon sheets. The frequency and magnitude of discharges decreased when layers of the pre-preg material were removed from the composite surface. These tests indicate that solar array panels may be used in the Jovian environment, but that electrostatic discharges can be expected on the carbon composite solar arrays.

Enhanced microwave absorption properties of epoxy composites containing graphite nanosheets@Fe3O4 decorated comb-like MnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Su, Xiaogang; Wang, Jun; Zhang, Bin; Chen, Wei; Wu, Qilei; Dai, Wei; Zou, Yi

2018-05-01

Recently, owing to the radiation and interference from electromagnetic wave (EMW), the requirements of EMW absorbing materials have been increasing. Herein, a novel absorber composed of graphite nanosheets@Fe3O4 composites decorated comb-like MnO2 (GNFM) has been successfully synthesized via a facile two steps, characterized using x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, vibrating sample magnetometry (VSM) and vector network analyzer (VNA). The ternary composites with enhanced microwave absorption performance are due to the complementary effects of electroconductive material (graphite nanosheets), dielectric materials (MnO2) and magnetic material (Fe3O4 nanospheres). Hence, the maximum reflection loss of GNFM/epoxy composites is up to ‑31.7 dB at 5.85 GHz with absorbing thickness of 4.5 mm, and the efficient frequency bandwidth below ‑10 dB can reach up to 4.47 GHz (11.87–16.34 GHz) at matching thickness of 2 mm. The results demonstrate that GNFM could be regarded as a novel type of microwave absorbing material.

An Analysis of Nondestructive Evaluation Techniques for Polymer Matrix Composite Sandwich Materials

NASA Technical Reports Server (NTRS)

Cosgriff, Laura M.; Roberts, Gary D.; Binienda, Wieslaw K.; Zheng, Diahua; Averbeck, Timothy; Roth, Donald J.; Jeanneau, Philippe

2006-01-01

Structural sandwich materials composed of triaxially braided polymer matrix composite material face sheets sandwiching a foam core are being utilized for applications including aerospace components and recreational equipment. Since full scale components are being made from these sandwich materials, it is necessary to develop proper inspection practices for their manufacture and in-field use. Specifically, nondestructive evaluation (NDE) techniques need to be investigated for analysis of components made from these materials. Hockey blades made from sandwich materials and a flat sandwich sample were examined with multiple NDE techniques including thermographic, radiographic, and shearographic methods to investigate damage induced in the blades and flat panel components. Hockey blades used during actual play and a flat polymer matrix composite sandwich sample with damage inserted into the foam core were investigated with each technique. NDE images from the samples were presented and discussed. Structural elements within each blade were observed with radiographic imaging. Damaged regions and some structural elements of the hockey blades were identified with thermographic imaging. Structural elements, damaged regions, and other material variations were detected in the hockey blades with shearography. Each technique s advantages and disadvantages were considered in making recommendations for inspection of components made from these types of materials.

Functional adaptation of crustacean exoskeletal elements through structural and compositional diversity: a combined experimental and theoretical study.

PubMed

Fabritius, Helge-Otto; Ziegler, Andreas; Friák, Martin; Nikolov, Svetoslav; Huber, Julia; Seidl, Bastian H M; Ruangchai, Sukhum; Alagboso, Francisca I; Karsten, Simone; Lu, Jin; Janus, Anna M; Petrov, Michal; Zhu, Li-Fang; Hemzalová, Pavlína; Hild, Sabine; Raabe, Dierk; Neugebauer, Jörg

2016-09-09

The crustacean cuticle is a composite material that covers the whole animal and forms the continuous exoskeleton. Nano-fibers composed of chitin and protein molecules form most of the organic matrix of the cuticle that, at the macroscale, is organized in up to eight hierarchical levels. At least two of them, the exo- and endocuticle, contain a mineral phase of mainly Mg-calcite, amorphous calcium carbonate and phosphate. The high number of hierarchical levels and the compositional diversity provide a high degree of freedom for varying the physical, in particular mechanical, properties of the material. This makes the cuticle a versatile material ideally suited to form a variety of skeletal elements that are adapted to different functions and the eco-physiological strains of individual species. This review presents our recent analytical, experimental and theoretical studies on the cuticle, summarising at which hierarchical levels structure and composition are modified to achieve the required physical properties. We describe our multi-scale hierarchical modeling approach based on the results from these studies, aiming at systematically predicting the structure-composition-property relations of cuticle composites from the molecular level to the macro-scale. This modeling approach provides a tool to facilitate the development of optimized biomimetic materials within a knowledge-based design approach.

Nanotechnology Based Green Energy Conversion Devices with Multifunctional Materials at Low Temperatures.

PubMed

Lu, Yuzheng; Afzal, Muhammad; Zhu, Bin; Wang, Baoyuan; Wang, Jun; Xia, Chen

2017-07-10

Nanocomposites (integrating the nano and composite technologies) for advanced fuel cells (NANOCOFC) demonstrate the great potential to reduce the operational temperature of solid oxide fuel cell (SOFC) significantly in the low temperature (LT) range 300-600ºC. NANOCOFC has offered the development of multi-functional materials composed of semiconductor and ionic materials to meet the requirements of low temperature solid oxide fuel cell (LTSOFC) and green energy conversion devices with their unique mechanisms. This work reviews the recent developments relevant to the devices and the patents in LTSOFCs from nanotechnology perspectives that reports advances including fabrication methods, material compositions, characterization techniques and cell performances. Finally, the future scope of LTSOFC with nanotechnology and the practical applications are also discussed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.

1995-01-01

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided.

16 CFR 24.2 - Deception as to composition.

Code of Federal Regulations, 2013 CFR

2013-01-01

... example: 2 With regard to footwear, it is sufficient to disclose the presence of non-leather materials in... Guides, footwear is composed of three parts: the upper, the lining and sock, and the outersole. These... the inside of the footwear article; and (3) the outersole is the bottom part of the footwear article...

16 CFR 24.2 - Deception as to composition.

Code of Federal Regulations, 2012 CFR

2012-01-01

... example: 2 With regard to footwear, it is sufficient to disclose the presence of non-leather materials in... Guides, footwear is composed of three parts: the upper, the lining and sock, and the outersole. These... the inside of the footwear article; and (3) the outersole is the bottom part of the footwear article...

16 CFR 24.2 - Deception as to composition.

Code of Federal Regulations, 2011 CFR

2011-01-01

... example: 2 With regard to footwear, it is sufficient to disclose the presence of non-leather materials in... Guides, footwear is composed of three parts: the upper, the lining and sock, and the outersole. These... the inside of the footwear article; and (3) the outersole is the bottom part of the footwear article...

16 CFR 24.2 - Deception as to composition.

Code of Federal Regulations, 2014 CFR

2014-01-01

... example: 2 With regard to footwear, it is sufficient to disclose the presence of non-leather materials in... Guides, footwear is composed of three parts: the upper, the lining and sock, and the outersole. These... the inside of the footwear article; and (3) the outersole is the bottom part of the footwear article...

Evaluation of 2D ceramic matrix composites in aeroconvective environments

NASA Technical Reports Server (NTRS)

Riccitiello, Salvatore R.; Love, Wendell L.; Balter-Peterson, Aliza

1992-01-01

An evaluation is conducted of a novel ceramic-matrix composite (CMC) material system for use in the aeroconvective-heating environments encountered by the nose caps and wing leading edges of such aerospace vehicles as the Space Shuttle, during orbit-insertion and reentry from LEO. These CMCs are composed of an SiC matrix that is reinforced with Nicalon, Nextel, or carbon refractory fibers in a 2D architecture. The test program conducted for the 2D CMCs gave attention to their subsurface oxidation.

Considerations concerning fatigue life of metal matrix composites

NASA Technical Reports Server (NTRS)

Radhakrishnan, V. M.; Bartolotta, Paul A.

1993-01-01

Since metal matrix composites (MMC) are composed from two very distinct materials each having their own physical and mechanical properties, it is feasible that the fatigue resistance depends on the strength of the weaker constituent. Based on this assumption, isothermal fatigue lives of several MMC's were analyzed utilizing a fatigue life diagram approach. For each MMC, the fatigue life diagram was quantified using the mechanical properties of its constituents. The fatigue life regions controlled by fiber fracture and matrix were also quantitatively defined.

Composition and diameter modulation of magnetic nanowire arrays fabricated by a novel approach

NASA Astrophysics Data System (ADS)

Shaker Salem, Mohamed; Tejo, Felipe; Zierold, Robert; Sergelius, Philip; Montero Moreno, Josep M.; Goerlitz, Detlef; Nielsch, Kornelius; Escrig, Juan

2018-02-01

Straight magnetic nanowires composed of nickel and permalloy segments having different diameters are synthesized using a promising approach. This approach involves the controlled electrodeposition of each magnetic material into specially designed diameter-modulated porous alumina templates. Standard alumina templates are exposed to pore widening followed by a protective coating of the pore wall with ultrathin silica and further anodization. Micromagnetic simulations are employed to investigate the process of magnetization reversal in the fabricated nanowires when the magnetic materials exchange their places in the thick and thin segments. It is found that the magnetization reversal occurs by the propagation of transverse domain wall (DW) when the thick segment is composed of permalloy. However, the reversal process proceeds by the propagation of vortex DW when permalloy is located at the thin segment.

Measurements of plutonium, 237Np, and 137Cs in the BCR 482 lichen reference material

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

Lavelle, Kevin B.; Miller, Jeffrey L.; Hanson, Susan K.

Select anthropogenic radionuclides were measured in lichen reference material, BCR 482. This material was originally collected in Axalp, Switzerland in 1991 and is composed of the epiphytic lichen Pseudevernia furfuracea. Samples from three separate bottles of BCR 482 were analyzed for uranium, neptunium, and plutonium isotopes by inductively coupled plasma mass spectrometry (ICP-MS) and analyzed for cesium-137 by gamma-ray spectrometry. The isotopic composition of the radionuclides measured in BCR 482 suggests contributions from both global fallout resulting from historical nuclear weapons testing and more volatile materials released following the Chernobyl accident.

Measurements of plutonium, 237Np, and 137Cs in the BCR 482 lichen reference material

DOE PAGES

Lavelle, Kevin B.; Miller, Jeffrey L.; Hanson, Susan K.; ...

2015-10-01

Select anthropogenic radionuclides were measured in lichen reference material, BCR 482. This material was originally collected in Axalp, Switzerland in 1991 and is composed of the epiphytic lichen Pseudevernia furfuracea. Samples from three separate bottles of BCR 482 were analyzed for uranium, neptunium, and plutonium isotopes by inductively coupled plasma mass spectrometry (ICP-MS) and analyzed for cesium-137 by gamma-ray spectrometry. The isotopic composition of the radionuclides measured in BCR 482 suggests contributions from both global fallout resulting from historical nuclear weapons testing and more volatile materials released following the Chernobyl accident.

Materials and structures for hypersonic vehicles

NASA Technical Reports Server (NTRS)

Tenney, Darrel R.; Lisagor, W. Barry; Dixon, Sidney C.

1988-01-01

Hypersonic vehicles are envisioned to require, in addition to carbon-carbon and ceramic-matrix composities for leading edges heated to above 2000 F, such 600 to 1800 F operating temperature materials as advanced Ti alloys, nickel aluminides, and metal-matrix composited; These possess the necessary low density and high strength and stiffness. The primary design drivers are maximum vehicle heating rate, total heat load, flight envelope, propulsion system type, mission life requirements and liquid hydrogen containment systems. Attention is presently given to aspects of these materials and structures requiring more intensive development.

Substantiation of artificial composite-structure roof construction in top-down cut-and-fill stoping

NASA Astrophysics Data System (ADS)

Rukavishnikov, GD; Neverov, SA; Neverov, AA

2018-03-01

It has been found efficient and safe to use top-down cut-and-fill stoping with saving of the artificial backfill cost and material through the use of a solid nonuniform material composed of two components (layers). It is shown that the artificial roof can be advanced after a stope without essential change in the stope condition as compared with the classical top-down slice method, which provides higher safety of mining.

Aspects regarding manufacturing technologies of composite materials for brake pad application

NASA Astrophysics Data System (ADS)

Craciun, A. L.; Hepuţ, T.; Pinca-Bretotean, C.

2018-01-01

Current needs in road safety, requires the development of new technical solutions for automotive braking system. Their safe operation is subject to following factors: concept design, materials used and electronic control. Among the factors previously listed, choice of materials and manufacturing processes are difficult stage but very important for achieving technical performance and getting a relatively small cost of constituting parts of brake system. The choice is based on the promotion of organic composite material, popular in areas where the weight of materials plays an important role. The brake system is composed of many different parts including brake pads, a master cylinder, wheel cylinders and a hydraulic control system. The brake pads are an important component in the braking system of automotive. These are of different types, suitable for different types of automotive and engines. Brake pads are designed for friction stability, durability, minimization of noise and vibration. The typology of the brake pads depends on the material which they are made. The aim of this paper is to presents the manufacturing technologies for ten recipes of composite material used in brake pads applications. In this work will be done: choosing the constituents of the recipes, investigation of their basic characteristics, setting the proportions of components, obtaining the composite materials in laboratory, establishing the parameters of manufacturing technology and technological analysis.

Surface Functionalized Nanostructured Ceramic Sorbents for the Effective Collection and Recovery of Uranium from Seawater

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

Chouyyok, Wilaiwan; Pittman, Jonathan W.; Warner, Marvin G.

2016-05-02

The ability to collect uranium from seawater offers the potential for a nearly limitless fuel supply for nuclear energy. We evaluated the use of functionalized nanostructured sorbents for the collection and recovery of uranium from seawater. Extraction of trace minerals from seawater and brines is challenging due to the high ionic strength of seawater, low mineral concentrations, and fouling of surfaces over time. We demonstrate that rationally assembled sorbent materials that integrate high affinity surface chemistry and high surface area nanostructures into an application relevant micro/macro structure enables collection performance that far exceeds typical sorbent materials. High surface area nanostructuredmore » silica with surface chemistries composed of phosphonic acid, phosphonates, 3,4 hydroxypyridinone, and EDTA showed superior performance for uranium collection. A few phosphorous-based commercial resins, specifically Diphonix and Ln Resin, also performed well. We demonstrate an effective and environmentally benign method of stripping the uranium from the high affinity sorbents using inexpensive nontoxic carbonate solutions. The cyclic use of preferred sorbents and acidic reconditioning of materials was shown to improve performance. Composite thin films composed of the nanostructured sorbents and a porous polymer binder are shown to have excellent kinetics and good capacity while providing an effective processing configuration for trace mineral recovery from solutions. Initial work using the composite thin films shows significant improvements in processing capacity over the previously reported sorbent materials.« less

Computerized Instruction in Translation Strategies for Students in Upper Elementary and Middle School Grades With Persisting Learning Disabilities in Written Language

PubMed Central

Niedo, Jasmin; Tanimoto, Steve; Thompson, Robert H.; Abbott, Robert D.; Berninger, Virginia W.

2016-01-01

Students in grades 5 to 9 (ages 10 to 14; 6 girls, 27 boys) who had persisting specific learning disabilities in transcription (handwriting and spelling) completed three kinds of composition tasks requiring translation (thought to written language) on iPads using alternating transcription modes (stylus or keyboard) across every three lessons: personal narratives (6 lessons) and written summaries about read source material (integrated reading-writing) and heard source material (integrated listening-writing) (12 lessons). Before composing summaries, students clicked sequentially one at a time onto translation strategies, which they read and heard through earphones, and could click on again as needed during summary writing: (a) Level I composing of the very next sentence, and (b) Level II composing of a higher-level discourse structure. ANOVAs showed that Level I strategies were used significantly more often than Level II strategies; but the main effect for transcription mode was not significant. Written summaries of read source material had more errors in main ideas and factual details than heard source materials, but not more irrelevant statements. Applications of results are discussed for using computers for writing instruction, not just accommodations, for students with persisting transcription disabilities. PMID:28670103

Off-Resonance Photosensitization of a Photorefractive Polymer Composite Using PbS Nanocrystals

DOE PAGES

Moon, Jong-Sik; Liang, Yichen; Stevens, Tyler E.; ...

2015-05-26

The photosensitization of photorefractive polymeric composites for operation at 633 nm is accomplished through the inclusion of narrow band gap semiconductor nanocrystals composed of PbS. Unlike previous studies involving photosensitization of photorefractive polymer composites with inorganic nanocrystals, we employ an off-resonance approach where the first excitonic transition associated with the PbS nanocrystals lies at ~1220 nm and not the wavelength of operation. Using this methodology, internal diffraction efficiencies exceeding 82%, two-beam-coupling gain coefficients of 211 cm –1, and response times of 34 ms have been observed, representing some of the best figures of merit reported for this class of materials.more » Furthermore, these data demonstrate the ability of semiconductor nanocrystals to compete effectively with traditional organic photosensitizers. In addition to superior performance, this approach also offers an inexpensive and easy means by which to photosensitize composite materials. Additionally, the photoconductive characteristics of the composites used for this study will also be considered.« less

Thermal Conductivity and Erosion Durability of Composite Two-Phase Air Plasma Sprayed Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Schmitt, Michael P.; Rai, Amarendra K.; Zhu, Dongming; Dorfman, Mitchell R.; Wolfe, Douglas E.

2015-01-01

To enhance efficiency of gas turbines, new thermal barrier coatings (TBCs) must be designed which improve upon the thermal stability limit of 7 wt% yttria stabilized zirconia (7YSZ), approximately 1200 C. This tenant has led to the development of new TBC materials and microstructures capable of improved high temperature performance. This study focused on increasing the erosion durability of cubic zirconia based TBCs, traditionally less durable than the metastable t' zirconia based TBCs. Composite TBC microstructures composed of a low thermal conductivity/high temperature stable cubic Low-k matrix phase and a durable t' Low-k secondary phase were deposited via APS. Monolithic coatings composed of cubic Low-k and t' Low-k were also deposited, in addition to a 7YSZ benchmark. The thermal conductivity and erosion durability were then measured and it was found that both of the Low-k materials have significantly reduced thermal conductivities, with monolithic t' Low-k and cubic Low-k improving upon 7YSZ by approximately 13 and approximately 25%, respectively. The 40 wt% t' Low-k composite (40 wt% t' Low-k - 60 wt% cubic Low-k) showed a approximately 22% reduction in thermal conductivity over 7YSZ, indicating even at high levels, the t' Low-k secondary phase had a minimal impact on thermal in the composite coating. It was observed that a mere 20 wt% t' Low-k phase addition can reduce the erosion of a cubic Low-k matrix phase composite coating by over 37%. Various mixing rules were then investigated to assess this non-linear composite behavior and suggestions were made to further improve erosion durability.

Interfacial Thickness Guidelines for SiC(Fiber)/SiC(Matrix) Composites

NASA Technical Reports Server (NTRS)

Hurst, Janet B.

1998-01-01

Researchers at the NASA Lewis Research Center have developed a guideline for the interface thickness necessary for SiC(Fiber)/SiC(Matrix) composites to demonstrate good composite properties. These composite materials have potential commercial applications for high-temperature structural components such as engine hot sections. Several samples of each were composed from three different small-diameter (less than 20 mm), polymer-derived SiC fibers that were woven into two-dimensional cloths and laid up as preforms. The preforms were treated with a chemical-vapor-infiltrated boron nitride layer as an interfacial coating on the fiber surfaces to provide the necessary debonding characteristics for successful composite behavior. Then, the preforms were filled with additional SiC as a matrix phase.

Design and Optimization of Composite Gyroscope Momentum Wheel Rings

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.

2007-01-01

Stress analysis and preliminary design/optimization procedures are presented for gyroscope momentum wheel rings composed of metallic, metal matrix composite, and polymer matrix composite materials. The design of these components involves simultaneously minimizing both true part volume and mass, while maximizing angular momentum. The stress analysis results are combined with an anisotropic failure criterion to formulate a new sizing procedure that provides considerable insight into the design of gyroscope momentum wheel ring components. Results compare the performance of two optimized metallic designs, an optimized SiC/Ti composite design, and an optimized graphite/epoxy composite design. The graphite/epoxy design appears to be far superior to the competitors considered unless a much greater premium is placed on volume efficiency compared to mass efficiency.

Fabrication and microstructures of functional gradient SiBCN–Nb composite by hot pressing

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

Sun, Min, E-mail: lcxsunmin@163.com; Fu, Ruoyu; Chen, Jun

2016-04-15

A functional gradient material with five layers composed of SiBCN ceramic and niobium (Nb) was prepared successfully by hot pressing. The phase composition, morphology features and microstructures were investigated in each layer of the gradient material. The Nb-containing compounds involving NbC, Nb{sub 6}C{sub 5}, Nb{sub 4}C{sub 3}, Nb{sub 5}Si{sub 3} and NbN increase with the volume fraction of Nb increasing in the sub-layer. They are randomly scattered (≤ 25 vol.% Nb), then strip-like, and finally distribute continuously (≥ 75 vol.% Nb). The size of BN(C) and SiC grains in Nb-containing layers is larger than in 100% SiBCN layer due tomore » the loss of the capsule-like structures. No distinct interfaces form in the transition regions indicating the gradual changes in phase composition and microstructures. - Highlights: • A functional gradient SiBCN–Nb material was prepared successfully by hot pressing. • Phase composition, morphology features and microstructures were investigated. • Thermodynamic calculation was used to aid in the phase analysis. • No distinct interfaces form typical of the functional gradient material.« less

Shape-morphing composites with designed micro-architectures

NASA Astrophysics Data System (ADS)

Rodriguez, Jennifer N.; Zhu, Cheng; Duoss, Eric B.; Wilson, Thomas S.; Spadaccini, Christopher M.; Lewicki, James P.

2016-06-01

Shape memory polymers (SMPs) are attractive materials due to their unique mechanical properties, including high deformation capacity and shape recovery. SMPs are easier to process, lightweight, and inexpensive compared to their metallic counterparts, shape memory alloys. However, SMPs are limited to relatively small form factors due to their low recovery stresses. Lightweight, micro-architected composite SMPs may overcome these size limitations and offer the ability to combine functional properties (e.g., electrical conductivity) with shape memory behavior. Fabrication of 3D SMP thermoset structures via traditional manufacturing methods is challenging, especially for designs that are composed of multiple materials within porous microarchitectures designed for specific shape change strategies, e.g. sequential shape recovery. We report thermoset SMP composite inks containing some materials from renewable resources that can be 3D printed into complex, multi-material architectures that exhibit programmable shape changes with temperature and time. Through addition of fiber-based fillers, we demonstrate printing of electrically conductive SMPs where multiple shape states may induce functional changes in a device and that shape changes can be actuated via heating of printed composites. The ability of SMPs to recover their original shapes will be advantageous for a broad range of applications, including medical, aerospace, and robotic devices.

Thermal conductivity of tubrostratic carbon nanofiber networks

DOE PAGES

Bauer, Matthew L.; Saltonstall, Chris B.; Leseman, Zayd C.; ...

2016-01-01

Composite material systems composed of a matrix of nano materials can achieve combinations of mechanical and thermophysical properties outside the range of traditional systems. While many reports have studied the intrinsic thermal properties of individual carbon fibers, to be useful in applications in which thermal stability is critical, an understanding of heat transport in composite materials is required. In this work, air/ carbon nano fiber networks are studied to elucidate the system parameters influencing thermal transport. Sample thermal properties are measured with varying initial carbon fiber fill fraction, environment pressure, loading pressure, and heat treatment temperature through a bidirectional modificationmore » of the 3ω technique. The nanostructures of the individual fibers are characterized with small angle x-ray scattering and Raman spectroscopy providing insight to individual fiber thermal conductivity. Measured thermal conductivity varied from 0.010 W/(m K) to 0.070 W/(m K). An understanding of the intrinsic properties of the individual fibers and the interactions of the two phase composite is used to reconcile low measured thermal conductivities with predictive modeling. This methodology can be more generally applied to a wide range of fiber composite materials and their applications.« less

Suleika and Hatem Revisited: Uncovering the Material Advantages of Identifying as a Male Composer

ERIC Educational Resources Information Center

Legg, Robert; Jeffery, David

2018-01-01

Persuasive arguments have been made for the existence of pedagogical discourses that invoke gender as a factor in the ascription of quality to musical compositions, and previous research has shown that some music teachers ascribe "maleness" to the characteristics that they regard as markers of high quality. Drawing upon Lucy Green's…

Cellulose nanocrystals as a reinforcing material for electrospun poly(methyl methacrylate) fibers: formation, properties and nanomechanical characterization

Treesearch

Hong Dong; Kenneth E. Strawhecker; James A. Snyder; Joshua A. Orlicki; Richard S. Reiner; Alan W. Rudie

2012-01-01

Uniform fibers composed of poly(methyl methacrylate) (PMMA) reinforced with progressively increasing contents of cellulose nanocrystals (CNCs), up to 41 wt% CNCs, have been successfully produced by electrospinning. The morphological, thermal and nanomechanical properties of the composite sub-micron fibers were investigated. The CNCs derived from wood pulp by sulfuric...

Solid electrolyte-electrode system for an electrochemical cell

DOEpatents

Tuller, H.L.; Kramer, S.A.; Spears, M.A.

1995-04-04

An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided. 17 figures.

Modeling of Damage Initiation and Progression in a SiC/SiC Woven Ceramic Matrix Composite

NASA Technical Reports Server (NTRS)

Mital, Subodh K.; Goldberg, Robert K.; Bonacuse, Peter J.

2012-01-01

The goal of an ongoing project at NASA Glenn is to investigate the effects of the complex microstructure of a woven ceramic matrix composite and its variability on the effective properties and the durability of the material. Detailed analysis of these complex microstructures may provide clues for the material scientists who `design the material? or to structural analysts and designers who `design with the material? regarding damage initiation and damage propagation. A model material system, specifically a five-harness satin weave architecture CVI SiC/SiC composite composed of Sylramic-iBN fibers and a SiC matrix, has been analyzed. Specimens of the material were serially sectioned and polished to capture the detailed images of fiber tows, matrix and porosity. Open source analysis tools were used to isolate various constituents and finite elements models were then generated from simplified models of those images. Detailed finite element analyses were performed that examine how the variability in the local microstructure affected the macroscopic behavior as well as the local damage initiation and progression. Results indicate that the locations where damage initiated and propagated is linked to specific microstructural features.

Impact of the material composition on proton range variation - A Monte Carlo study

NASA Astrophysics Data System (ADS)

Wu, S. W.; Tung, C. J.; Lee, C. C.; Fan, K. H.; Huang, H. C.; Chao, T. C.

2015-11-01

In this study, we used the Geant4 toolkit to demonstrate the impacts of the material composition of tissues on proton range variation. Bragg curves of different materials subjected to a 250 MeV mono-energy proton beam were simulated and compared. These simulated materials included adipose, heart, brain, cartilage, cortical bone and water. The results showed that there was significant proton range deviation between Bragg curves, especially for cortical bone. The R50 values for a 250 MeV proton beam were approximately 39.55 cm, 35.52 cm, 37.00 cm, 36.51 cm, 36.72 cm, 22.53 cm, and 38.52 cm in the phantoms that were composed completely of adipose, cartilage, tissue, heart, brain, cortical bone, and water, respectively. Mass density and electron density were used to scale the proton range for each material; electron density provided better range scaling. In addition, a similar comparison was performed by artificially setting all material density to 1.0 g/cm3 to evaluate the range deviation due to chemical components alone. Tissue heterogeneity effects due to density variation were more significant, and less significant for chemical composition variation unless the Z/A was very different.

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.

Biocompatible silk-conducting polymer composite trilayer actuators

NASA Astrophysics Data System (ADS)

Fengel, Carly V.; Bradshaw, Nathan P.; Severt, Sean Y.; Murphy, Amanda R.; Leger, Janelle M.

2017-05-01

Biocompatible materials capable of controlled actuation are in high demand for use in biomedical applications such as dynamic tissue scaffolding, valves, and steerable surgical tools. Conducting polymer actuators are of interest because they operate in aqueous electrolytes at low voltages and can generate stresses similar to natural muscle. Recently, our group has demonstrated a composite material of silk and poly(pyrrole) (PPy) that is mechanically robust, made from biocompatible materials, and bends under an applied voltage when incorporated into a simple bilayer device architecture and actuated using a biologically relevant electrolyte. Here we present trilayer devices composed of two silk-PPy composite layers separated by an insulating silk layer. The trilayer architecture allows one side to expand while the other contracts, resulting in improved performance over bilayer devices. Specifically, this configuration shows a larger angle of deflection per volt applied than the analogous bilayer system, while maintaining a consistent current response throughout cycling. In addition, the overall motion of the trilayer devices is more symmetric than that of the bilayer analogs, allowing for fully reversible operation.

Nuclear fuel elements made from nanophase materials

DOEpatents

Heubeck, Norman B.

1998-01-01

A nuclear reactor core fuel element is composed of nanophase high temperature materials. An array of the fuel elements in rod form are joined in an open geometry fuel cell that preferably also uses such nanophase materials for the cell structures. The particular high temperature nanophase fuel element material must have the appropriate mechanical characteristics to avoid strain related failure even at high temperatures, in the order of about 3000.degree. F. Preferably, the reactor type is a pressurized or boiling water reactor and the nanophase material is a high temperature ceramic or ceramic composite. Nanophase metals, or nanophase metals with nanophase ceramics in a composite mixture, also have desirable characteristics, although their temperature capability is not as great as with all-ceramic nanophase material. Combinations of conventional or nanophase metals and conventional or nanophase ceramics can be employed as long as there is at least one nanophase material in the composite. The nuclear reactor so constructed has a number of high strength fuel particles, a nanophase structural material for supporting a fuel rod at high temperature, a configuration to allow passive cooling in the event of a primary cooling system failure, an ability to retain a coolable geometry even at high temperatures, an ability to resist generation of hydrogen gas, and a configuration having good nuclear, corrosion, and mechanical characteristics.

Nuclear fuel elements made from nanophase materials

DOEpatents

Heubeck, N.B.

1998-09-08

A nuclear reactor core fuel element is composed of nanophase high temperature materials. An array of the fuel elements in rod form are joined in an open geometry fuel cell that preferably also uses such nanophase materials for the cell structures. The particular high temperature nanophase fuel element material must have the appropriate mechanical characteristics to avoid strain related failure even at high temperatures, in the order of about 3000 F. Preferably, the reactor type is a pressurized or boiling water reactor and the nanophase material is a high temperature ceramic or ceramic composite. Nanophase metals, or nanophase metals with nanophase ceramics in a composite mixture, also have desirable characteristics, although their temperature capability is not as great as with all-ceramic nanophase material. Combinations of conventional or nanophase metals and conventional or nanophase ceramics can be employed as long as there is at least one nanophase material in the composite. The nuclear reactor so constructed has a number of high strength fuel particles, a nanophase structural material for supporting a fuel rod at high temperature, a configuration to allow passive cooling in the event of a primary cooling system failure, an ability to retain a coolable geometry even at high temperatures, an ability to resist generation of hydrogen gas, and a configuration having good nuclear, corrosion, and mechanical characteristics. 5 figs.

Computational Studies of Thermodynamics and Kinetics of Metal Oxides in Li-Ion Batteries and Earth's Lower Mantle Materials

NASA Astrophysics Data System (ADS)

Xu, Shenzhen

Metal oxide materials are ubiquitous in nature and in our daily lives. For example, the Earth's mantle layer that makes up about 80% of our Earth's volume is composed of metal oxide materials, the cathode materials in the lithium-ion batteries that provide power for most of our mobile electronic devices are composed of metal oxides, the chemical components of the passivation layers on many kinds of metal materials that protect the metal from further corrosion are metal oxides. This thesis is composed of two major topics about the metal oxide materials in nature. The first topic is about our computational study of the iron chemistry in the Earth's lower mantle metal oxide materials, i.e. the bridgmanite (Fe-bearing MgSiO3 where iron is the substitution impurity element) and the ferropericlase (Fe-bearing MgO where iron is the substitution impurity element). The second topic is about our multiscale modeling works for understanding the nanoscale kinetic and thermodynamic properties of the metal oxide cathode interfaces in Li-ion batteries, including the intrinsic cathode interfaces (intergrowth of multiple types of cathode materials, compositional gradient cathode materials, etc.), the cathode/coating interface systems and the cathode/electrolyte interface systems. This thesis uses models based on density functional theory quantum mechanical calculations to explore the underlying physics behind several types of metal oxide materials existing in the interior of the Earth or used in the applications of lithium-ion batteries. The exploration of this physics can help us better understand the geochemical and seismic properties of our Earth and inspire us to engineer the next generation of electrochemical technologies.

Characterization, Modeling, and Failure Analysis of Composite Structure Materials under Static and Dynamic Loading

NASA Astrophysics Data System (ADS)

Werner, Brian Thomas

Composite structures have long been used in many industries where it is advantageous to reduce weight while maintaining high stiffness and strength. Composites can now be found in an ever broadening range of applications: sporting equipment, automobiles, marine and aerospace structures, and energy production. These structures are typically sandwich panels composed of fiber reinforced polymer composite (FRPC) facesheets which provide the stiffness and the strength and a low density polymeric foam core that adds bending rigidity with little additional weight. The expanding use of composite structures exposes them to high energy, high velocity dynamic loadings which produce multi-axial dynamic states of stress. This circumstance can present quite a challenge to designers, as composite structures are highly anisotropic and display properties that are sensitive to loading rates. Computer codes are continually in development to assist designers in the creation of safe, efficient structures. While the design of an optimal composite structure is more complex, engineers can take advantage of the effect of enhanced energy dissipation displayed by a composite when loaded at high strain rates. In order to build and verify effective computer codes, the underlying assumptions must be verified by laboratory experiments. Many of these codes look to use a micromechanical approach to determine the response of the structure. For this, the material properties of the constituent materials must be verified, three-dimensional constitutive laws must be developed, and failure of these materials must be investigated under static and dynamic loading conditions. In this study, simple models are sought not only to ease their implementation into such codes, but to allow for efficient characterization of new materials that may be developed. Characterization of composite materials and sandwich structures is a costly, time intensive process. A constituent based design approach evaluates potential combinations of materials in a much faster and more efficient manner.

On the Mechanical Behavior of Advanced Composite Material Structures

NASA Astrophysics Data System (ADS)

Vinson, Jack

During the period between 1993 and 2004, the author, as well as some colleagues and graduate students, had the honor to be supported by the Office of Naval Research to conduct research in several aspects of the behavior of structures composed of composite materials. The topics involved in this research program were numerous, but all contributed to increasing the understanding of how various structures that are useful for marine applications behaved. More specifically, the research topics focused on the reaction of structures that were made of fiber reinforced polymer matrix composites when subjected to various loads and environmental conditions. This included the behavior of beam, plate/panel and shell structures. It involved studies that are applicable to fiberglass, graphite/carbon and Kevlar fibers imbedded in epoxy, polyester and other polymeric matrices. Unidirectional, cross-ply, angle ply, and woven composites were involved, both in laminated, monocoque as well as in sandwich constructions. Mid-plane symmetric as well as asymmetric laminates were studied, the latter involving bending-stretching coupling and other couplings that only can be achieved with advanced composite materials. The composite structures studied involved static loads, dynamic loading, shock loading as well as thermal and hygrothermal environments. One major consideration was determining the mechanical properties of composite materials subjected to high strain rates because the mechanical properties vary so significantly as the strain rate increases. A considerable number of references are cited for further reading and study for those interested.

Interlayer toughening of fiber composite flywheel rotors

DOEpatents

Groves, Scott E.; Deteresa, Steven J.

1998-01-01

An interlayer toughening mechanism to mitigate the growth of damage in fiber composite flywheel rotors for long application. The interlayer toughening mechanism may comprise one or more tough layers composed of high-elongation fibers, high-strength fibers arranged in a woven pattern at a range from 0.degree. to 90.degree. to the rotor axis and bound by a ductile matrix material which adheres to and is compatible with the materials used for the bulk of the rotor. The number and spacing of the tough interlayers is a function of the design requirements and expected lifetime of the rotor. The mechanism has particular application in uninterruptable power supplies, electrical power grid reservoirs, and compulsators for electric guns, as well as electromechanical batteries for vehicles.

Interlayer toughening of fiber composite flywheel rotors

DOEpatents

Groves, S.E.; Deteresa, S.J.

1998-07-14

An interlayer toughening mechanism is described to mitigate the growth of damage in fiber composite flywheel rotors for long application. The interlayer toughening mechanism may comprise one or more tough layers composed of high-elongation fibers, high-strength fibers arranged in a woven pattern at a range from 0{degree} to 90{degree} to the rotor axis and bound by a ductile matrix material which adheres to and is compatible with the materials used for the bulk of the rotor. The number and spacing of the tough interlayers is a function of the design requirements and expected lifetime of the rotor. The mechanism has particular application in uninterruptable power supplies, electrical power grid reservoirs, and compulsators for electric guns, as well as electromechanical batteries for vehicles. 2 figs.

Chondrulelike objects in short-period comet 81P/Wild 2.

PubMed

Nakamura, Tomoki; Noguchi, Takaaki; Tsuchiyama, Akira; Ushikubo, Takayuki; Kita, Noriko T; Valley, John W; Zolensky, Michael E; Kakazu, Yuki; Sakamoto, Kanako; Mashio, Etsuko; Uesugi, Kentaro; Nakano, Tsukasa

2008-09-19

The Stardust spacecraft returned cometary samples that contain crystalline material, but the origin of the material is not yet well understood. We found four crystalline particles from comet 81P/Wild 2 that were apparently formed by flash-melting at a high temperature and are texturally, mineralogically, and compositionally similar to chondrules. Chondrules are submillimeter particles that dominate chondrites and are believed to have formed in the inner solar nebula. The comet particles show oxygen isotope compositions similar to chondrules in carbonaceous chondrites that compose the middle-to-outer asteroid belt. The presence of the chondrulelike objects in the comet suggests that chondrules have been transported out to the cold outer solar nebula and spread widely over the early solar system.

Lightweight Thermal Protection System for Atmospheric Entry

NASA Technical Reports Server (NTRS)

Stewart, David; Leiser, Daniel

2007-01-01

TUFROC (Toughened Uni-piece Fibrous Reinforced Oxidation-resistant Composite) has been developed as a new thermal protection system (TPS) material for wing leading edge and nose cap applications. The composite withstands temperatures up to 1,970 K, and consists of a toughened, high-temperature surface cap and a low-thermal-conductivity base, and is applicable to both sharp and blunt leading edge vehicles. This extends the possible application of fibrous insulation to the wing leading edge and/or nose cap on a hypersonic vehicle. The lightweight system comprises a treated carbonaceous cap composed of ROCCI (Refractory Oxidation-resistant Ceramic Carbon Insulation), which provides dimensional stability to the outer mold line, while the fibrous base material provides maximum thermal insulation for the vehicle structure.

Application of fiber-reinforced bismaleimide materials to aircraft nacelle structures

NASA Technical Reports Server (NTRS)

Peros, Vasilios; Ruth, John; Trawinski, David

1992-01-01

Existing aircraft engine nacelle structures employ advanced composite materials to reduce weight and thereby increase overall performance. Use of advanced composite materials on existing aircraft nacelle structures includes fiber-reinforced epoxy structures and has typically been limited to regions furthest away from the hot engine core. Portions of the nacelle structure that are closer to the engine require materials with a higher temperature capability. In these portions, existing nacelle structures employ aluminum sandwich construction and skin/stringer construction. The aluminum structure is composed of many detail parts and assemblies and is usually protected by some form of ablative, insulator, or metallic thermal shield. A one-piece composite inner cowl for a new-generation engine nacelle structure has been designed using fiber-reinforced bismaleimide (BMI) materials and honeycomb core in a sandwich construction. The new composite design has many advantages over the existing aluminum structure. Multiple details were integrated into the one-piece composite design, thereby significantly reducing the number of detail parts and fasteners. The use of lightweight materials and the reduction of the number of joints result in a significant weight reduction over the aluminum design; manufacturing labor and the overall number of tools required have also been reduced. Several significant technical issues were addressed in the development of a BMI composite design. Technical evaluation of the available BMI systems led to the selection of a toughened BMI material which was resistant to microcracking under thermal cyclic loading and enhanced the damage tolerance of the structure. Technical evaluation of the degradation of BMI materials in contact with aluminum and other metals validated methods for isolation of the various materials. Graphite-reinforced BMI in contact with aluminum and some steels was found to degrade in salt spray testing. Isolation techniques such as those used for graphite-reinforced epoxy structures were shown to provide adequate protection. The springback and producibility of large BMI structures were evaluated by manufacturing prototype hardware which had the full-scale cross section of the one-piece composite structure.

Defect induced guided waves mode conversion

NASA Astrophysics Data System (ADS)

Wandowski, Tomasz; Kudela, Pawel; Malinowski, Pawel; Ostachowicz, Wieslaw

2016-04-01

This paper deals with analysis of guided waves mode conversion phenomenon in fiber reinforced composite materials. Mode conversion phenomenon may take place when propagating elastic guided waves interact with discontinuities in the composite waveguide. The examples of such discontinuities are sudden thickness change or delamination between layers in composite material. In this paper, analysis of mode conversion phenomenon is based on full wave-field signals. In the full wave-field approach signals representing propagation of elastic waves are gathered from dense mesh of points that span over investigated area of composite part. This allow to animate the guided wave propagation. The reported analysis is based on signals resulting from numerical calculations and experimental measurements. In both cases defect in the form of delamination is considered. In the case of numerical research, Spectral Element Method (SEM) is utilized, in which a mesh is composed of 3D elements. Numerical model includes also piezoelectric transducer. Full wave-field experimental measurements are conducted by using piezoelectric transducer for guided wave excitation and Scanning Laser Doppler Vibrometer (SLDV) for sensing.

Proteome Speciation by Mass Spectrometry: Characterization of Composite Protein Mixtures in Milk Replacers.

PubMed

Gaspari, Marco; Chiesa, Luca; Nicastri, Annalisa; Gabriele, Caterina; Harper, Valeria; Britti, Domenico; Cuda, Giovanni; Procopio, Antonio

2016-12-06

The ability of tandem mass spectrometry to determine the primary structure of proteolytic peptides can be exploited to trace back the organisms from which the corresponding proteins were extracted. This information can be important when food products, such as protein powders, can be supplemented with lower-quality starting materials. In order to dissect the origin of proteinaceous material composing a given unknown mixture, a two-step database search strategy for bottom-up nanoscale liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) data was implemented. A single nanoLC-MS/MS analysis was sufficient not only to determine the qualitative composition of the mixtures under examination, but also to assess the relative percent composition of the various proteomes, if dedicated calibration curves were previously generated. The approach of two-step database search for qualitative analysis and proteome total ion current (pTIC) calculation for quantitative analysis was applied to several binary and ternary mixtures which mimic the composition of milk replacers typically used in calf feeding.

Powder Metallurgical Synthesis of Biodegradable Mg-Hydroxyapatite Composites for Biomedical Applications

NASA Astrophysics Data System (ADS)

Stüpp, Cesar Augusto; Szakács, Gábor; Mendis, Chamini Lakshi; Gensch, Felix; Müller, Sören; Feyerabend, Frank; Hotza, Dachamir; Fredel, Marcio Celso; Hort, Norbert

Magnesium alloys with acceptable or even controllable corrosion rates, where mechanical properties are not significantly modified or worsened, have been increasingly investigated in the last decade for use as biomaterials. This work shows an approach with a magnesium metal matrix composite (Mg-MMC), composed of ZK60 as base material and hydroxyapatite (HA) particles. The composite was produced by mechanical alloying followed by hot extrusion, as HA in contact with molten magnesium releases toxic gases such as phosphine (PH3). This work will present the influence of different amounts of HA on corrosion behaviour and mechanical properties of the investigated composites. Compared to the ZK60 alloy, corrosion is expected to be delayed, without localized corrosion. The mechanical properties are not expected to be compromised with such composite during tissue's healing period.

Biocompatibility of NiTi alloys in the cell behaviour.

PubMed

Sevcikova, Jana; Pavkova Goldbergova, Monika

2017-04-01

Metallic biomaterial alloys composed of nickel and titanium have unique thermal shape memory, superelastic, and high damping properties, which are widely used in the medicine. The major parameter evaluated in the studies regarding the behaviour of the material in the contact with organism or cells is biocompatibility. The aim of the studies is to clarify the differences in the proliferation, growth, and morphology especially in the cell cultures. The cytotoxicity is affected among other by release of the metal ions in the presence of the metal alloy, which is further dependent on the possible treatments of the material and the corrosive properties. To evaluate the cytotoxicity, wide range of tests including the Sulforhodamine B assay and MTT tests, expression profiles, cell survival tests such as apoptotic test are used. The review compares the cell behaviour in contact with the material alloys composed of nickel and titanium with respect to different materials composition and different surface treatment that affects the ion release. Even though the results published so far are controversial, almost all data suggest sufficient biocompatibility in medical use.

Intermetallics as innovative CRM-free materials

NASA Astrophysics Data System (ADS)

Novák, Pavel; Jaworska, Lucyna; Cabibbo, Marcello

2018-03-01

Many of currently used technical materials cannot be imagined without the use of critical raw materials. They require chromium (e.g. in stainless and tool steels), tungsten and cobalt (tool materials, heat resistant alloys), niobium (steels and modern biomaterials). Therefore there is a need to find substitutes to help the European economy. A promising solution can be the application of intermetallics. These materials offer wide variety of interesting properties, such as high hardness and wear resistance or high chemical resistance. In this paper, the overview of possible substitute materials among intermetallics is presented. Intermetallics based on aluminides and silicides are shown as corrosion resistant materials, composites composed of ceramics in intermetallic matrix as possible tool materials. The manufacturing processes are being developed to minimize the disadvantages of these materials, mainly the room-temperature brittleness.

Combination of sorption properties of polydimethylsiloxane and solid-phase extraction sorbents in a single composite material for the passive sampling of polar and apolar pesticides in water.

PubMed

Martin, Alexis; Margoum, Christelle; Coquery, Marina; Randon, Jérôme

2016-10-01

Passive sampling techniques have been developed as an alternative method for in situ integrative monitoring of trace levels of neutral pesticides in environmental waters. The objective of this work was to develop a new receiving phase for pesticides with a wide range of polarities in a single step. We describe the development of three new composite silicone rubbers, combining polydimethylsiloxane mechanical and sorption properties with solid-phase extraction sorbents, prepared as a receiving phase for passive sampling. A composite silicone rubber composed of polydimethylsiloxane/poly(divinylbenzene-co-N-vinylpyrrolidone) was selected by batch experiments for its high sorption properties for pesticides with octanol-water partition coefficients ranging from 2.3 to 5.5. We named this composite material "Polar/Apolar Composite Silicone Rubber". A structural study by scanning electron microscopy confirmed the homogeneous dispersion of the sorbent particles and the encapsulation of particles within the polydimethylsiloxane matrix. We also demonstrate that this composite material is resistant to common solvents used for the back-extraction of analytes and has a maximal resistance temperature of 350°C. Therefore, the characteristics of the "Polar/Apolar Composite Silicone Rubber" meet most of the criteria for use as a receiving phase for the passive sampling of pesticides. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Laboratory study of fungal bioreceptivity of different fractions of composite flooring tiles showing efflorescence.

PubMed

Masaphy, Segula; Lavi, Ido; Sultz, Stephan; Zabari, Limor

2014-06-01

Fungi can grow in extreme habitats, such as natural stone and mineral building materials, sometimes causing deterioration. Efflorescence-concentrated salt deposits-results from water movement through building material; it can damage masonry materials and other bricks. Fungal isolate KUR1, capable of growth on, and dissolution of stone chips composing terrazzo-type floor tiles, was isolated from such tiles showing fiber-like crystalline efflorescence. The isolate's ribosomal DNA sequences were 100 % identical to those of Nigrospora sphaerica. The ability of KUR1 to colonize and degrade the different stone chips composing the tiles was studied in axenic culture experiments. When exposed to each of the different mineral chip types composed of dolomite, calcite, or calcite-apatite mineral in low-nutrition medium, the fungus showed selective nutrient consumption, and different growth and stone mineral dissolution rates. Micromorphological examination of the fungus-colonized chips by electron microscopy showed the production of a fungal biofilm with thin films around the hyphae on the surface of the examined chips and disintegration of the calcite-apatite fraction. More than 70 % dissolution of the introduced powdered (<1 mm particle size) mineral was obtained within 10 days of incubation for the soft calcite-apatite fraction.

Shape-morphing composites with designed micro-architectures

DOE PAGES

Rodriguez, Jennifer N.; Zhu, Cheng; Duoss, Eric B.; ...

2016-06-15

Shape memory polymers (SMPs) are attractive materials due to their unique mechanical properties, including high deformation capacity and shape recovery. SMPs are easier to process, lightweight, and inexpensive compared to their metallic counterparts, shape memory alloys. However, SMPs are limited to relatively small form factors due to their low recovery stresses. Lightweight, micro-architected composite SMPs may overcome these size limitations and offer the ability to combine functional properties (e.g., electrical conductivity) with shape memory behavior. Fabrication of 3D SMP thermoset structures via traditional manufacturing methods is challenging, especially for designs that are composed of multiple materials within porous microarchitectures designedmore » for specific shape change strategies, e.g. sequential shape recovery. We report thermoset SMP composite inks containing some materials from renewable resources that can be 3D printed into complex, multi-material architectures that exhibit programmable shape changes with temperature and time. Through addition of fiber-based fillers, we demonstrate printing of electrically conductive SMPs where multiple shape states may induce functional changes in a device and that shape changes can be actuated via heating of printed composites. As a result, the ability of SMPs to recover their original shapes will be advantageous for a broad range of applications, including medical, aerospace, and robotic devices.« less

Impact of solids on composite materials

NASA Technical Reports Server (NTRS)

Bronson, Arturo; Maldonado, Jerry; Chern, Tzong; Martinez, Francisco; Mccord-Medrano, Johnnie; Roschke, Paul N.

1987-01-01

The failure modes of composite materials as a result of low velocity impact were investigated by simulating the impact with a finite element analysis. An important facet of the project is the modeling of the impact of a solid onto cylindrical shells composed of composite materials. The model under development will simulate the delamination sustained when a composite material encounters impact from another rigid body. The computer equipment was installed, the computer network tested, and a finite element method model was developed to compare results with known experimental data. The model simulated the impact of a steel rod onto a rotating shaft. Pre-processing programs (GMESH and TANVEL) were developed to generate node and element data for the input into the three dimensional, dynamic finite element analysis code (DYNA3D). The finite element mesh was configured with a fine mesh near the impact zone and a coarser mesh for the impacting rod and the regions surrounding the impacting zone. For the computer simulation, five impacting loads were used to determine the time history of the stresses, the scribed surface areas, and the amount of ridging. The processing time of the computer codes amounted from 1 to 4 days. The calculated surface area were within 6-12 percent, relative error when compated to the actual scratch area.

Experimental investigation of fiberglass sandwich composite bending behaviour after severe aging condition

NASA Astrophysics Data System (ADS)

Gambaro, Carla; Lertora, Enrico; Mandolfino, Chiara

2016-10-01

Fiber Reinforced Polymer (FRP) sandwich panels are increasing their application as structural and non-structural components in all kinds of construction. By varying the material and thickness of core and face sheets, it is possible to obtain sandwich structures with different properties and performance. In particular, their advantages as lightweight and high mechanical properties make them extremely suitable for the transport industry. One of the most critical aspects regarding composite materials for engineering application is their performance after hygrothermal aging. The panels used in this study are composed of low density core, made by thermosetting resin foam with microspheres and glass fibers rolled until obtaining the required thickness, and two face sheets of the same material but realized in high density. In this study, the authors focused on the bending behaviour of this kind of sandwich panel, as received and after severe aging cycles.

The Features of Self-Assembling Organic Bilayers Important to the Formation of Anisotropic Inorganic Materials in Microgravity Conditions

NASA Technical Reports Server (NTRS)

Talham, Daniel R.; Adair, James H.

1999-01-01

There is a growing need for inorganic anisotropic particles in a variety of materials science applications. Structural, optical, and electrical properties can be greatly augmented by the fabrication of composite materials with anisotropic microstructures or with anisotropic particles uniformly dispersed in an isotropic matrix. Examples include structural composites, magnetic and optical recording media, photographic film, certain metal and ceramic alloys, and display technologies including flat panel displays. While considerable progress has been made toward developing an understanding of the synthesis of powders composed of monodispersed, spherical particles, these efforts have not been transferred to the synthesis of anisotropic nanoparticles. The major objective of the program is to develop a fundamental understanding of the growth of anisotropic particles at organic templates, with emphasis on the chemical and structural aspects of layered organic assemblies that contribute to the formation of anisotropic inorganic particles.

Development of a composite geodetic structure for space construction, phase 1A

NASA Technical Reports Server (NTRS)

1980-01-01

The development of a geodetic beam and beam builder for on orbit construction of large truss type space structures is discussed. The geodetic beam is a lightweight, open lattice structure composed of an equilateral gridwork of crisscrossing rods. The beam provides a high degree of stiffness and minimizes structural distortion, due to temperature gradients, through the incorporation of a new graphite and glass reinforced thermoplastic composite material with a low coefficient of thermal expansion. A low power consuming, high production rate, beam builder automatically fabricates the geodetic beams in space using rods preprocessed on Earth. Three areas of the development are focused upon; (1) geodetic beam designs for local attachment of equipment or beam to beam joining in a parallel or crossing configurations, (2) evaluation of long life pultruded rods capable of service temperatures higher than possible with the HMS/P1700 rod material, and (3) evalaution of high temperature joint encapsulant materials.

Third-generation pure alumina and alumina matrix composites in total hip arthroplasty

PubMed Central

Hannouche, Didier; Zingg, Matthieu; Miozzari, Hermes; Nizard, Remy; Lübbeke, Anne

2018-01-01

Wear, corrosion and periprosthetic osteolysis are important causes of failure in joint arthroplasty, especially in young patients. Ceramic bearings, developed 40 years ago, are an increasingly popular choice in hip arthroplasty. New manufacturing procedures have increased the strength and reliability of ceramic materials and reduced the risk of complications. In recent decades, ceramics made of pure alumina have continuously improved, resulting in a surgical-grade material that fulfills clinical requirements. Despite the track record of safety and long-term results, third-generation pure alumina ceramics are being replaced in clinical practice by alumina matrix composites, which are composed of alumina and zirconium. In this review, the characteristics of both materials are discussed, and the long-term results with third-generation alumina-on-alumina bearings and the associated complications are compared with those of other available ceramics. Cite this article: EFORT Open Rev 2018;3:7-14. DOI: 10.1302/2058-5241.3.170034 PMID:29657840

Chemistry of Martian Soils from the Mars Exploration Rover APXS Instruments

NASA Technical Reports Server (NTRS)

Mittlefehldt, D. W.; Gellert, R.; Yen, A.

2007-01-01

The martian surface is covered with debris formed by several mechanisms and mobilized by various processes. Volcanism, impact, physical weathering and chemical alteration combine to produce particles of sizes from dust to boulders composed of primary mineral and rock fragments, partially altered primary materials, alteration minerals and shock-modified materials from all of these. Impacts and volcanism produce localized deposits. Winds transport roughly sand-sized material over intermediate distances, while periodic dust storms deposit a global dust layer of the finest fraction. The compositions of clastic sediments can be used to evaluate regional differences in crustal composition and/or weathering processes. Here we examine the growing body of chemical data on soils in Gusev crater and Meridiani Planum returned by the Alpha Particle X-ray Spectrometer (APXS) instruments on the rovers Spirit (MERA) and Opportunity (MERB), following on earlier results based on smaller data sets [1-4].

Glyoxal Crosslinking of Cell-Seeded Chitosan/Collagen Hydrogels for Bone Regeneration

PubMed Central

Wang, Limin; Stegemann, Jan P.

2011-01-01

Chitosan and collagen are natural biomaterials that have been used extensively in tissue engineering, both separately and as composite materials. Most methods to fabricate chitosan/collagen composites use freeze drying and chemical crosslinking to create stable porous scaffolds, which subsequently can be seeded with cells. In this study, we directly embedded human bone marrow stem cells (hBMSC) in chitosan/collagen materials by initiating gelation using β-glycerophosphate at physiological temperature and pH. We further examined the use of glyoxal, a dialdehyde with relatively low toxicity, to crosslink these materials and characterized the resulting changes in matrix and cell properties. The cytocompatibility of glyoxal and the crosslinked gels were investigated in terms of hBMSC metabolic activity, viability, proliferation, and osteogenic differentiation. These studies revealed that glyoxal was cytocompatible at concentrations below about 1 mM for periods of exposure up to 15 h, though the degree of cell spreading and proliferation were dependent on matrix composition. Glyoxal-crosslinked matrices were stiffer and compacted less than uncrosslinked controls. It was further demonstrated that hBMSC can attach and proliferate in 3D matrices composed of 50/50 chitosan/collagen, and that these materials supported osteogenic differentiation in response to stimulation. Such glyoxal-crosslinked chitosan/collagen composite materials may find utility as cell delivery vehicles for enhancing the repair of bone defects. PMID:21345389

Materials for Heated Head Automated Thermoplastic Tape Placement

NASA Technical Reports Server (NTRS)

Jensen, Brian J.; Kinney, Megan C.; Cano, Roberto J.; Grimsley, Brian W.

2012-01-01

NASA Langley Research Center (LaRC) is currently pursuing multiple paths to develop out of autoclave (OOA) polymeric composite materials and processes. Polymeric composite materials development includes the synthesis of new and/or modified thermosetting and thermoplastic matrix resins designed for specific OOA processes. OOA processes currently under investigation include vacuum bag only (VBO) prepreg/composite fabrication, resin transfer molding (RTM), vacuum assisted resin transfer molding (VARTM) and heated head automated thermoplastic tape placement (HHATP). This paper will discuss the NASA Langley HHATP facility and capabilities and recent work on characterizing thermoplastic tape quality and requirements for quality part production. Samples of three distinct versions of APC-2 (AS4/PEEK) thermoplastic dry tape were obtained from two materials vendors, TENCATE, Inc. and CYTEC Engineered Materials** (standard grade and an experimental batch). Random specimens were taken from each of these samples and subjected to photo-microscopy and surface profilometry. The CYTEC standard grade of APC-2 tape had the most voids and splits and the highest surface roughness and/or waviness. Since the APC-2 tape is composed of a thermoplastic matrix, it offers the flexibility of reprocessing to improve quality, and thereby improve final quality of HHATP laminates. Discussions will also include potential research areas and future work that is required to advance the state of the art in the HHATP process for composite fabrication.

Modeling of short fiber reinforced injection moulded composite

NASA Astrophysics Data System (ADS)

Kulkarni, A.; Aswini, N.; Dandekar, C. R.; Makhe, S.

2012-09-01

A micromechanics based finite element model (FEM) is developed to facilitate the design of a new production quality fiber reinforced plastic injection molded part. The composite part under study is composed of a polyetheretherketone (PEEK) matrix reinforced with 30% by volume fraction of short carbon fibers. The constitutive material models are obtained by using micromechanics based homogenization theories. The analysis is carried out by successfully coupling two commercial codes, Moldflow and ANSYS. Moldflow software is used to predict the fiber orientation by considering the flow kinetics and molding parameters. Material models are inputted into the commercial software ANSYS as per the predicted fiber orientation and the structural analysis is carried out. Thus in the present approach a coupling between two commercial codes namely Moldflow and ANSYS has been established to enable the analysis of the short fiber reinforced injection moulded composite parts. The load-deflection curve is obtained based on three constitutive material model namely an isotropy, transversely isotropy and orthotropy. Average values of the predicted quantities are compared to experimental results, obtaining a good correlation. In this manner, the coupled Moldflow-ANSYS model successfully predicts the load deflection curve of a composite injection molded part.

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

Bradshaw, Nathan P.; Severt, Sean Y.; Wang, Zhaoying

Biocompatible materials capable of controlled actuation under biologically relevant conditions are in high demand for use in a number of biomedical applications. Recently, we demonstrated that a composite material composed of silk biopolymer and the conducting polymer poly(pyrrole) can bend under an applied voltage using a simple bilayer device. Here we present further characterization of these bilayer actuators using time of flight secondary ion mass spectrometry, and provide clarification on the mechanism of actuation and factors affecting device performance and stability. We will discuss the results of this study in the context of strategies for optimization of device performance.

Pyroclastic Activity at Home Plate in Gusev Crater, Mars

NASA Technical Reports Server (NTRS)

Squyres, S. W.; Aharonson, O.; Clark, B. S.; Cohen, B.; Crumpler, L.; deSouza, P. A.; Farrand, W. H.; Gellert, R.; Grant, J.; Grotzinger, J. P.;

Pyroclastic activity at home plate in Gusev crater, Mars

USGS Publications Warehouse

Squyres, S. W.; Aharonson, O.; Clark, B. C.; Cohen, B. A.; Crumpler, L.; de Souza, P.A.; Farrand, W. H.; Gellert, Ralf; Grant, J.; Grotzinger, J.P.; Haldemann, A.F.C.; Johnson, J. R.; Klingelhofer, G.; Lewis, K.W.; Li, R.; McCoy, T.; McEwen, A.S.; McSween, H.Y.; Ming, D. W.; Moore, Johnnie N.; Morris, R.V.; Parker, T.J.; Rice, J. W.; Ruff, S.; Schmidt, M.; Schroder, C.; Soderblom, L.A.; Yen, A.

2007-01-01

Home Plate is a layered plateau in Gusev crater on Mars. It is composed of clastic rocks of moderately altered alkali basalt composition, enriched in some highly volatile elements. A coarse-grained lower unit lies under a finer-grained upper unit. Textural observations indicate that the lower strata were emplaced in an explosive event, and geochemical considerations favor an explosive volcanic origin over an impact origin. The lower unit likely represents accumulation of pyroclastic materials, whereas the upper unit may represent eolian reworking of the same pyroclastic materials.

Monte carlo simulation of innovative neutron and photon shielding material composing of high density concrete, waste rubber, lead and boron carbide

NASA Astrophysics Data System (ADS)

Aim-O, P.; Wongsawaeng, D.; Phruksarojanakun, P.; Tancharakorn, S.

2017-06-01

High-density concrete exhibits high strength and can perform an important role of gamma ray attenuation. In order to upgrade this material’s radiation-shielding performance, hydrogen-rich material can be incorporated. Waste rubber from vehicles has high hydrogen content which is the prominent characteristic to attenuate neutron. The objective of this work was to evaluate the radiation-shielding properties of this composite material against neutron and photon radiations. Monte Carlo transport simulation was conducted to simulate radiation through the composite material. Am-241/Be was utilized for neutron source and Co-60 for photon source. Parameters of the study included volume percentages of waste rubber, lead and boron carbide and thickness of the shielding material. These designs were also fabricated and the radiation shielding properties were experimentally evaluated. The best neutron and gamma ray shielding material was determined to be high-density concrete mixed with 5 vol% crumb rubber and 5 vol% lead powder. This shielding material increased the neutron attenuation by 64% and photon attenuation by 68% compared to ordinary concrete. Also, increasing the waste rubber content to greater than 5% resulted in a decrease in the radiation attenuation. This innovative composite radiation shielding material not only benefits nuclear science and engineering applications, but also helps solve the environmental issue of waste rubber.

Phase composition of Katowice - Wełnowiec pytometallurgical slags: preliminary SEM study

NASA Astrophysics Data System (ADS)

Warchulski, Rafał; Szopa, Krzysztof

2014-09-01

Exploitation on Zn-Pb ores in Upper Silesia region dates back to the XIII century. Analyzed slags are associated with Hohenlohe smelting plant which started its work in 1804 as an iron smelter, and continued as zinc smelter since 1873. Waste material from smelting plant production was stored in Katowice - Wełnowiec, although nowadays most of it has been used for commercial purposes. Slags are composed of silicates and aluminosilicates, e.g. willemite, pyroxene- and melilite-group, K-feldspar accompanied by silico-phosphates close to perhamite, harrisonite and arsenate-chloride with composition similar to nealite. Chemical composition of most phases is simple with some unique substitutions in case of Sr and Ce

Phase Composition of Katowice - Wełnowiec Pytometallurgical Slags: Preliminary SEM Study

NASA Astrophysics Data System (ADS)

Warchulski, Rafał; Szopa, Krzysztof

2014-09-01

Exploitation on Zn-Pb ores in Upper Silesia region dates back to the XIII century. Analyzed slags are associated with Hohenlohe smelting plant which started its work in 1804 as an iron smelter, and continued as zinc smelter since 1873. Waste material from smelting plant production was stored in Katowice - Wełnowiec, although nowadays most of it has been used for commercial purposes. Slags are composed of silicates and aluminosilicates, e.g. willemite, pyroxene- and melilite-group, K-feldspar accompanied by silico-phosphates close to perhamite, harrisonite and arsenate-chloride with composition similar to nealite. Chemical composition of most phases is simple with some unique substitutions in case of Sr and Ce.

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

Kobayashi, Takehiko; Nojima, Toshio; Yamada, Kenji

A dry phantom material having the same electric properties in the UHF band as biological tissues is developed. The new composite material is composed of microwave ceramic powder, graphite powder, and bonding resin. This material overcomes the various problems inherent in the conventional jelly phantom material, such as dehydration and deterioration due to invasion of bacteria or mold. This innovation of the phantom material makes it possible to accomplish highly reliable and precise estimation of specific absorption rate (SAR) in biological systems. Dry phantom models of spheres and human heads are fabricated. Experiments are performed to estimate the SAR ofmore » human heads exposed to microwave sources by using the thermography method. Since this material removes the necessity of the phantom shell indispensable with the conventional jelly material, the surface SAR distribution can be readily obtained.« less

Sea urchin skeleton: Structure, composition, and application as a template for biomimetic materials

NASA Astrophysics Data System (ADS)

Shapkin, Nikolay P.; Khalchenko, Irina G.; Panasenko, Alexander E.; Drozdov, Anatoly L.

2017-07-01

SEM and optical microscopy, chemical and EDX analysis, XRD, and FT-IR spectroscopy of three sea urchins skeletons (tests) show that the test is a spongy stereom, consisting of calcite with high content of magnesium. The tests are composed of mineral-organic composite of calcite-magnesite crystals, coated with organic film, containing silicon in form of polyphenylsiloxane. In the test of sea urchin pore spaces are linked into united system of regular structure with structure motive period about 20 um. This developed three-dimensional structure was used as a template for polymer material based on polyferrofenilsiloxane [OSiC6H5OH]x[OSiC6H5O]y[OFeO]z, which is chemically similar to the native film, coating sea urchins skeleton.

Method of producing a ceramic fiber-reinforced glass-ceramic matrix composite

NASA Technical Reports Server (NTRS)

Bansal, Narottam P. (Inventor)

1994-01-01

A fiber-reinforced composite composed of a BaO-Al2O3-2SiO2 (BAS) glass ceramic matrix is reinforced with CVD silicon carbide continuous fibers. A slurry of BAS glass powders is prepared and celsian seeds are added during ball melting. The slurry is cast into tapes which are cut to the proper size. Continuous CVD-SiC fibers are formed into mats of the desired size. The matrix tapes and the fiber mats are alternately stacked in the proper orientation. This tape-mat stack is warm pressed to produce a 'green' composite. The 'green' composite is then heated to an elevated temperature to burn out organic constituents. The remaining interim material is then hot pressed to form a silicon carbide fiber-reinforced celsian (BAS) glass-ceramic matrix composite which may be machined to size.

Determination of anisotropy and multimorphology in fly ash based geopolymers

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

Khan, M. Irfan, E-mail: mirfanwazir@gmail.com; Azizli, Khairun, E-mail: khairun-azizli@petronas.com.my; Sufian, Suriati, E-mail: suriati@petronas.com.my

2015-07-22

In this study, Malaysian coal fly ash-based geopolymers were investigated for its morphology and chemical composition using scanning electron microscopy coupled with energy dispersive X-rays (SEM-EDX). Geopolymer was synthesized using sodium hydroxide as activator. SEM studies revealed multiphasous structure of the material, composed of geopolymeric gel, partially reacted fly ashparticles and selectively leached particles. EDX analysis confirmed the chemical composition of different regions. Infra red spectroscopic studies supported the SEM-EDX analysis by confirming presence of unreacted quartzite and mullite in geopolymers. It is concluded that geopolymers possese a non uniform chemistry through out the structure.

Determination of anisotropy and multimorphology in fly ash based geopolymers

NASA Astrophysics Data System (ADS)

Khan, M. Irfan; Azizli, Khairun; Sufian, Suriati; Man, Zakaria; Siyal, Ahmer Ali; Ullah, Hafeez

2015-07-01

In this study, Malaysian coal fly ash-based geopolymers were investigated for its morphology and chemical composition using scanning electron microscopy coupled with energy dispersive X-rays (SEM-EDX). Geopolymer was synthesized using sodium hydroxide as activator. SEM studies revealed multiphasous structure of the material, composed of geopolymeric gel, partially reacted fly ashparticles and selectively leached particles. EDX analysis confirmed the chemical composition of different regions. Infra red spectroscopic studies supported the SEM-EDX analysis by confirming presence of unreacted quartzite and mullite in geopolymers. It is concluded that geopolymers possese a non uniform chemistry through out the structure.

Curved Thermopiezoelectric Shell Structures Modeled by Finite Element Analysis

NASA Technical Reports Server (NTRS)

Lee, Ho-Jun

2000-01-01

"Smart" structures composed of piezoelectric materials may significantly improve the performance of aeropropulsion systems through a variety of vibration, noise, and shape-control applications. The development of analytical models for piezoelectric smart structures is an ongoing, in-house activity at the NASA Glenn Research Center at Lewis Field focused toward the experimental characterization of these materials. Research efforts have been directed toward developing analytical models that account for the coupled mechanical, electrical, and thermal response of piezoelectric composite materials. Current work revolves around implementing thermal effects into a curvilinear-shell finite element code. This enhances capabilities to analyze curved structures and to account for coupling effects arising from thermal effects and the curved geometry. The current analytical model implements a unique mixed multi-field laminate theory to improve computational efficiency without sacrificing accuracy. The mechanics can model both the sensory and active behavior of piezoelectric composite shell structures. Finite element equations are being implemented for an eight-node curvilinear shell element, and numerical studies are being conducted to demonstrate capabilities to model the response of curved piezoelectric composite structures (see the figure).

Compositional Evidence for Launch Pairing of the YQ and Elephant Moraine Lunar Meteorites

NASA Technical Reports Server (NTRS)

Korotev, R. L.; Jollitt, B. L.; Zeigler, R. A.; Haskin, L. A.

2003-01-01

Arai and Warren provide convincing evidence that QUE (Queen Alexandra Range) 94281 derives from the same regolith as Y (Yamato) 793274 and, therefore, that the two meteorites were likely ejected from the Moon by the same impact. Recently discovered Y981031 is paired with Y793274. The "YQ" meteorites (Y793274/Y981031 and QUE 94281 are unique among lunar meteorites in being regolith breccias composed of subequal amounts of mare volcanic material (a VLT [very-low-Ti] basalt or gabbro) and feldspathic highland material. EET (Elephant Moraine) 87521 and its pair EET 96008 are fragmental breccias composed mainly of VLT basalt or gabbro. Warren, Arai, and colleagues note that the volcanic components of the YQ and EET meteorites are texturally similar more similar to each other than either is to mare basalts of the Apollo collection. Warren and colleagues address the issue of possible launch pairing of YQ and EET, but note compositional differences between EET and the volcanic component of YQ, as inferred from extrapolations of regressions to high FeO concentration. We show here that: (1) EET 87/96 consists of fragments of a differentiated magma body, (2) subsamples of EET represent a mixing trend between Fe-rich and Mg-rich differentiates, and (3) the inferred volcanic component of YQ is consistent with a point on the EET mixing line. Thus, there is no compositional impediment to the hypothesis that YQ is launch paired with EET.

Synthesis and evaluation of bioceramics for orthopedics and tissue culture applications

NASA Astrophysics Data System (ADS)

Demirkiran, Hande

Hydroxyapatite is the most well known phosphate in the biologically active phosphate ceramic family by virtue of its similarity to natural bone mineral. Among all bioglass compositions BioglassRTM45S5 is one of the most bioactive glasses. This study initially started by adding different amounts (1, 2.5, 5, 10, and 25 wt.%) of BioglassRTM45S5 to synthetic hydroxyapatite in order to improve the bioactivity of these bioceramics. The chemistries formed by sintering and their effect on different material properties including bioactivity were identified by using various techniques, such as powder and thin film x-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, X-ray absorption near edge spectroscopy, compression test, and nano indentation. All the results demonstrated that 10 and 25 wt.% BioglassRTM45S5 addition to hydroxyapatite and sintering at 1200°C for 4 hours yield new compositions with main Ca 5(PO4)2SiO4 and Na3Ca 6(PO4)5 crystalline phases dispersed in silicate glassy matrices, respectively. In addition, in vitro bioactivity tests such as bone like apatite formation in simulated body fluid and bone marrow stromal cell culture have shown that the crystalline and amorphous phases have an important role on improving bioactivity of these bioceramic compositions. Besides, compression test and nano indentation has given important information on compression strength and nano structure properties of these newly composed bioceramic materials and the bone like apatite layers formed on them, respectively. Finally, the effect of silicate addition on both formation and bioactivity of Na3Ca6(PO4)5 bioceramics were shown. These findings and different techniques used assisted to develop a phenomenological approach to demonstrate how the novel bioceramic compositions were composed and aid improving bioactivity of known bioceramic materials.

A New Fiber Preform with Nanocarbon Binder for Manufacturing Carbon Fiber Reinforced Composite by Liquid Molding Process.

PubMed

Seong, Dong Gi; Ha, Jong Rok; Lee, Jea Uk; Lee, Wonoh; Kim, Byung Sun

2015-11-01

Carbon fiber reinforced composite has been a good candidate of lightweight structural component in the automotive industry. As fast production speed is essential to apply the composite materials for the mass production area such as automotive components, the high speed liquid composite molding processes have been developed. Fast resin injection through the fiber preform by high pressure is required to improve the production speed, but it often results in undesirable deformations of the fiber preform which causes defectives in size and properties of the final composite products. In order to prevent the undesirable deformation and improve the stability of preform shape, polymer type binder materials are used. More stable fiber preform can be obtained by increasing the amount of binder material, but it disturbs the resin impregnation through the fiber preform. In this study, carbon nanomaterials such as graphene oxide were embedded on the surface of carbon fiber by electrophoretic deposition method in order to improve the shape stability of fiber preform and interfacial bonding between polymer and the reinforcing fiber. Effects of the modified reinforcing fiber were investigated in two respects. One is to increase the binding energy between fiber tows, and the other is to increase the interfacial bonding between polymer matrix and fiber surface. The effects were analyzed by measuring the binding force of fiber preform and interlaminar shear strength of the composite. This study also investigated the high speed liquid molding process of the composite materials composed of polymer matrix and the carbon fiber preforms embedded by carbon nanomaterials. Process parameter such as permeability of fiber preform was measured to investigate the effect of nanoscale surface modification on the macroscale processing condition for composite manufacturing.

Facile synthesis of reduced graphene oxide/peroxomolybdate(VI)-citrate composite and its potential energy storage application

NASA Astrophysics Data System (ADS)

Ciszewski, Mateusz; Benke, Grzegorz; Leszczyńska-Sejda, Katarzyna; Kopyto, Dorota

2017-11-01

A new energy storage material based on molybdate active species has been presented. Molybdenum seems to be a perspective material in supercapacitors because of numerous possible metal oxidation states, electrolyte storage by means of various chemical reactions and availability in comparison to other refractory metals. Material synthesized within this research was composed of reduced graphene oxide matrix and peroxomolybdate(VI)-citrate active dimers. It was showed that peroxomolybdate(VI)-citrate structure enhanced electrochemical activity of symmetric supercapacitor. Simple methodology was used to synthesize a composite with pH adjustment as the key step. The specific capacity calculated from galvanostatic charge/discharge curves was as high as 250 F/g. Material was distinguished by good cyclability with 5% capacity loss after 1000 cycles. The increase in charge transfer resistance, induced by metal-oxygen compound within the carbon matrix was relatively low, compared to parent reduced graphene oxide. Amorphous structure of peroxomolybdate(VI)-modified material was observed with slight increase in the interlayer distance in comparison to parent reduced graphene oxide. The height and lateral size of crystallites were also determined. Significant decrease in the specific surface area of peroxomolybdate(VI)-modified composite was observed, in comparison to the parent reduced graphene oxide.

Electromagnetic valve for controlling the flow of molten, magnetic material

DOEpatents

Richter, T.

1998-06-16

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell. 5 figs.

Electromagnetic valve for controlling the flow of molten, magnetic material

DOEpatents

Richter, Tomas

1998-01-01

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell.

Bulk metallic glass matrix composites: Processing, microstructure, and application as a kinetic energy penetrator

NASA Astrophysics Data System (ADS)

Dandliker, Richard B.

The development of alloys with high glass forming ability allows fabrication of bulk samples of amorphous metal. This capability makes these materials available for applications which require significant material thickness in all three dimensions. Superior mechanical properties and advantages in processing make metallic glass a choice candidate as a matrix material for composites. This study reports techniques for making composites by melt-infiltration casting using the alloy Zrsb{41.2}Tisb{13.8}Cusb{12.5}Nisb{10.0}Besb{22.5} (VitreloyspTM 1) as a matrix material. Composite rods 5 cm in length and 7 mm in diameter were made and found to have a nearly fully amorphous matrix; there was less than 3 volume percent crystallized matrix material. The samples were reinforced by continuous metal wires, tungsten powder, or silicon carbide particulate preforms. The most easily processed samples were made with uniaxially aligned tungsten and carbon steel continuous wire reinforcement; the majority of the analysis presented is of these samples. The measured porosity was typically less than 3%. The results also indicate necessary guidelines for developing processing techniques for large scale production, new reinforcement materials, and other metallic glass compositions. Analysis of the microstructure of the tungsten wire and steel wire reinforced composites was performed by x-ray diffraction, scanning electron microscopy, scanning Auger microscopy, transmission electron microscopy, and energy dispersive x-ray spectroscopy. The most common phase in the crystallized matrix is most likely a Laves phase with the approximate formula Besb{12}Zrsb3TiNiCu. In tungsten-reinforced composites, a crystalline reaction layer 240 nm thick of tungsten nanocrystals in an amorphous matrix formed. In the steel reinforced composites, the reaction layer was primarily composed of a mixed metal carbide, mainly ZrC. One promising application of the metallic glass matrix composite is as a kinetic energy penetrator material. Ballistic tests show that a composite of 80 volume percent uniaxially aligned tungsten wires and a VitreloyspTM 1 matrix has self-sharpening behavior, which is a necessary characteristic of superior penetrator materials. Small-scale tests with both aluminum and steel targets show that this composite performs better than tungsten heavy alloys typically used for penetrator applications, and comparably with depleted uranium.

Multi-Draft Composing: An Iterative Model for Academic Argument Writing

ERIC Educational Resources Information Center

Eckstein, Grant; Chariton, Jessica; McCollum, Robb Mark

2011-01-01

Post-secondary writing teachers in composition and English as a second language (ESL) writing programs are likely familiar with multi-draft composing. Both composition and ESL writing programs share nearly identical multi-draft models despite the very unique and different cultures of each group. We argue that multi-draft composing as it is…

Directly writing resistor, inductor and capacitor to composite functional circuits: a super-simple way for alternative electronics.

PubMed

Gao, Yunxia; Li, Haiyan; Liu, Jing

2013-01-01

The current strategies for making electronic devices are generally time, water, material and energy consuming. Here, the direct writing of composite functional circuits through comprehensive use of GaIn10-based liquid metal inks and matching material is proposed and investigated, which is a rather easy going and cost effective electronics fabrication way compared with the conventional approaches. Owing to its excellent adhesion and electrical properties, the liquid metal ink was demonstrated as a generalist in directly making various basic electronic components such as planar resistor, inductor and capacitor or their combination and thus composing circuits with expected electrical functions. For a precise control of the geometric sizes of the writing, a mask with a designed pattern was employed and demonstrated. Mechanisms for justifying the chemical components of the inks and the magnitudes of the target electronic elements so as to compose various practical circuits were disclosed. Fundamental tests on the electrical components including capacitor and inductor directly written on paper with working time up to 48 h and elevated temperature demonstrated their good stability and potential widespread adaptability especially when used in some high frequency circuits. As the first proof-of-concept experiment, a typical functional oscillating circuit including an integrated chip of 74HC04 with a supply voltage of 5 V, a capacitor of 10 nF and two resistors of 5 kΩ and 1 kΩ respectively was directly composed on paper through integrating specific electrical elements together, which presented an oscillation frequency of 8.8 kHz. The present method significantly extends the roles of the metal ink in recent works serving as only a single electrical conductor or interconnecting wires. It opens the way for directly writing out complex functional circuits or devices on different substrates. Such circuit composition strategy has generalized purpose and can be extended to more areas, even daily pervasive electronics.

Directly Writing Resistor, Inductor and Capacitor to Composite Functional Circuits: A Super-Simple Way for Alternative Electronics

PubMed Central

Gao, Yunxia; Li, Haiyan; Liu, Jing

2013-01-01

Background The current strategies for making electronic devices are generally time, water, material and energy consuming. Here, the direct writing of composite functional circuits through comprehensive use of GaIn10-based liquid metal inks and matching material is proposed and investigated, which is a rather easy going and cost effective electronics fabrication way compared with the conventional approaches. Methods Owing to its excellent adhesion and electrical properties, the liquid metal ink was demonstrated as a generalist in directly making various basic electronic components such as planar resistor, inductor and capacitor or their combination and thus composing circuits with expected electrical functions. For a precise control of the geometric sizes of the writing, a mask with a designed pattern was employed and demonstrated. Mechanisms for justifying the chemical components of the inks and the magnitudes of the target electronic elements so as to compose various practical circuits were disclosed. Results Fundamental tests on the electrical components including capacitor and inductor directly written on paper with working time up to 48 h and elevated temperature demonstrated their good stability and potential widespread adaptability especially when used in some high frequency circuits. As the first proof-of-concept experiment, a typical functional oscillating circuit including an integrated chip of 74HC04 with a supply voltage of 5 V, a capacitor of 10 nF and two resistors of 5 kΩ and 1 kΩ respectively was directly composed on paper through integrating specific electrical elements together, which presented an oscillation frequency of 8.8 kHz. Conclusions The present method significantly extends the roles of the metal ink in recent works serving as only a single electrical conductor or interconnecting wires. It opens the way for directly writing out complex functional circuits or devices on different substrates. Such circuit composition strategy has generalized purpose and can be extended to more areas, even daily pervasive electronics. PMID:23936349

Development of Refined Natural Resin based Cashew Nut Shell Oil Liquid (CNSL) for Brake Pads Composite

NASA Astrophysics Data System (ADS)

Wahyuningsih, S.; Ramelan, A. H.; Rahmawati, P.; Tamtama, B. P. N.; Sari, P. P.; Sari, P. L.; Ichsan, S.; Kristiawan, Y. R.; Aini, F. N.

2017-02-01

Brake is one of the most important components in the vehicle. One type of brake that widely used is brake-based composites. One of the manufacture of composite material is resin. Cashew Nut Shell Liquid (CNSL) is a natural material which has chemical structure similar to synthetic phenol so it can be an alternative as a resin. Brake pads manufacture using CNSL as resin composites made to obtain the brake which is strong, wear-resistant, and environmentally friendly. The composite made using powder metallurgy techniques by mixing ingredients such as rubber, fibre glass, carbon, mineral sands and phenolic resin. Two formulas were composed by varying the resin and iron mineral sands in 5 grams. Composites were tested using Universal Testing Machine (UTM). The tensile strength result of those formulas are 600 N and 900 N and the elongations are 1.98 mm and 2.59 mm respectively. Formula 2 has a better tensile strength due to the addition of more resin is 15%. Since the better properties, formula 2 was derivated to 4 extended formulas and showed excellent pressure strength reached 20.000 N. It indicates that the addition of the resin can improve the mechanical properties of a composite.

Characterizing the Properties of a Woven SiC/SiC Composite Using W-CEMCAN Computer Code

NASA Technical Reports Server (NTRS)

Murthy, Pappu L. N.; Mital, Subodh K.; DiCarlo, James A.

1999-01-01

A micromechanics based computer code to predict the thermal and mechanical properties of woven ceramic matrix composites (CMC) is developed. This computer code, W-CEMCAN (Woven CEramic Matrix Composites ANalyzer), predicts the properties of two-dimensional woven CMC at any temperature and takes into account various constituent geometries and volume fractions. This computer code is used to predict the thermal and mechanical properties of an advanced CMC composed of 0/90 five-harness (5 HS) Sylramic fiber which had been chemically vapor infiltrated (CVI) with boron nitride (BN) and SiC interphase coatings and melt-infiltrated (MI) with SiC. The predictions, based on the bulk constituent properties from the literature, are compared with measured experimental data. Based on the comparison. improved or calibrated properties for the constituent materials are then developed for use by material developers/designers. The computer code is then used to predict the properties of a composite with the same constituents but with different fiber volume fractions. The predictions are compared with measured data and a good agreement is achieved.

Hierarchical flower-like C/NiO composite hollow microspheres and its excellent supercapacitor performance

NASA Astrophysics Data System (ADS)

Liu, Tao; Jiang, Chuanjia; Cheng, Bei; You, Wei; Yu, Jiaguo

2017-08-01

Nickel (II) oxide (NiO) nanosheet grown on N-doped carbon hollow spheres (NiO/NCHS) with hierarchical pore structure are obtained via facile chemical bath deposition followed by calcination at 350 °C under nitrogen atmosphere. Phase structure measurements indicate that the material is composed of NiO and N-doped carbon. The NiO/NCHS composite exhibits a unique flower-like morphology, where ultrathin NiO nanosheets are vertically grown on the surface of NCHS. This hierarchical nanostructure is beneficial for facilitating electron and electrolyte ion transport and accelerating the reversible redox reaction. The specific capacitance of the NiO/NCHS composite (585 F g-1 at 1 A g-1) is higher than that of pure NiO particle (453 F g-1 at 1 A g-1). Meanwhile, the NiO/NCHS composite exhibits excellent rate performance and superior cycling stability over 6000 cycles. The enhanced supercapacitive performance of the NiO/NCHS nanocomposite indicates that it can be an appealing candidate electrode material for supercapacitors.

Characterization of Inorganic Filler Content, Mechanical Properties, and Light Transmission of Bulk-fill Resin Composites.

PubMed

Fronza, B M; Ayres, Apa; Pacheco, R R; Rueggeberg, F A; Dias, Cts; Giannini, M

The aims of this study were to characterize inorganic content (IC), light transmission (LT), biaxial flexural strength (BFS), and flexural modulus (FM) of one conventional (layered) and four bulk-fill composites at different depths. Bulk-fill composites tested were Surefil SDR flow (SDR), Filtek Bulk Fill (FBF), Tetric EvoCeram Bulk Fill (TEC), and EverX Posterior (EXP). Herculite Classic (HER) was used as a control. Energy dispersive x-ray analysis and scanning electron microscopy were used to characterize filler particle composition and morphology. The LT through different composite thicknesses (1, 2, 3, and 4 mm) was measured using a laboratory-grade spectral radiometer system (n=5). For the BFS and FM tests, sets of eight stacked composite discs (0.5-mm thick) were prepared simulating bulk filling of a 4-mm-thick increment (n=8). SDR demonstrated larger, irregular particles than those observed in TEC or HER. Filler particles in FBF were spherical, while those in EXP were composed of fiberglass strands. The LT decreased with increased composite thickness for all materials. Bulk-fill composites allowed higher LT than the HER. Furthermore, HER proved to be the unique material, having lower BFS values at deeper regions. SDR, FBF, and TEC bulk-fill composites presented reduced FM with increasing composite depth. The bulk-fill composites investigated exhibited higher LT, independent of different filler content and characteristics. Although an increase in composite thickness reduced LT, the BFS of bulk-fill composites at deeper layers was not compromised.

Novel, inorganic composites using porous, alkali-activated, aluminosilicate binders

NASA Astrophysics Data System (ADS)

Musil, Sean

Geopolymers are an inorganic polymeric material composed of alumina, silica, and alkali metal oxides. Geopolymers are chemical and fire resistant, can be used as refractory adhesives, and are processed at or near ambient temperature. These properties make geopolymer an attractive choice as a matrix material for elevated temperature composites. This body of research investigated numerous different reinforcement possibilities and variants of geopolymer matrix material and characterized their mechanical performance in tension, flexure and flexural creep. Reinforcements can then be chosen based on the resulting properties to tailor the geopolymer matrix composites to a specific application condition. Geopolymer matrix composites combine the ease of processing of polymer matrix composites with the high temperature capability of ceramic matrix composites. This study incorporated particulate, unidirectional fiber and woven fiber reinforcements. Sodium, potassium, and cesium based geopolymer matrices were evaluated with cesium based geopolymer showing great promise as a high temperature matrix material. It showed the best strength retention at elevated temperature, as well as a very low coefficient of thermal expansion when crystallized into pollucite. These qualities made cesium geopolymer the best choice for creep resistant applications. Cesium geopolymer binders were combined with unidirectional continuous polycrystalline mullite fibers (Nextel(TM) 720) and single crystal mullite fibers, then the matrix was crystallized to form cubic pollucite. Single crystal mullite fibers were obtained by the internal crystallization method and show excellent creep resistance up to 1400°C. High temperature flexural strength and flexural creep resistance of pollucite and polycrystalline/single-crystal fibers was evaluated at 1000-1400°C.

Experimental investigation on IXV TPS interface effects in Plasmatron

NASA Astrophysics Data System (ADS)

Ceglia, Giuseppe; Trifoni, Eduardo; Gouriet, Jean-Baptiste; Chazot, Olivier; Mareschi, Vincenzo; Rufolo, Giuseppe; Tumino, Giorgio

2016-06-01

An experimental investigation related to the thermal protection system (TPS) interfaces of the intermediate experimental vehicle has been carried out in the Plasmatron facility at the von Karman Institute for fluid dynamics. The objective of this test campaign is to qualify the thermal behaviours of two different TPS interfaces under flight representative conditions in terms of heat flux and integral heat load ( 180 kW/m2 for 700 s). Three test samples are tested in off-stagnation configuration installed on an available flat plate holder under the same test conditions. The first junction is composed of an upstream ceramic matrix composite (CMC) plate and an ablative P50 cork composite block separated by a gap of 2 mm. The second one is made of an upstream P50 block and a downstream ablative SV2A silicon elastomer block with silicon-based filler in between. A sample composed of P50 material is tested in order to obtain reference results without TPS interface effect. The overheating at the CMC-P50 interface due to the jump of the catalytic properties of the materials, and the recession/swelling behaviour of the P50-SV2A interface are under investigation. All the test samples withstand relatively well the imposed heat flux for the test duration. As expected, both the ablative materials undergo a thermal degradation. The P50 exhibits the formation of a porous char layer and its recession; on the other hand, the SV2A swells and forms a fragile char layer.

Middle school students' beliefs about matter

NASA Astrophysics Data System (ADS)

Nakhleh, Mary B.; Samarapungavan, Ala; Saglam, Yilmaz

2005-05-01

The objective of this study was to examine middle school students' developing understanding of the nature of matter and to compare middle school students' ideas to those of elementary schools students, as was done by Nakhleh and Samarapungavan [J Res Sci Teach 36(7):777-805, 1999]. Nine middle school students were interviewed using a scripted, semistructured interview. The interview probed students' understanding of the composition and particulate (atomic/molecular) structure of a variety of material substances; the relationship between particulate structure and macroscopic properties such as fluidity and malleability; as well as understanding of processes such as phase transition and dissolving. The results indicate that most of the middle school students interviewed knew that matter was composed of atoms and molecules and some of them were able to use this knowledge to explain some processes such as phase transitions of water. In contrast, almost no elementary students knew that matter was composed of atoms and molecules. However, the middle school students were unable to consistently explain material properties or processes based on their knowledge of material composition. In contrast to elementary school students, who had scientifically inaccurate but relatively consistent (macrocontinuous or macroparticulate) knowledge frameworks, the middle school students could not be classified as having consistent knowledge frameworks because their ideas were very fragmented. The fragmentation of middle school students' ideas about matter probably reflects the difficulty of assimilating the microscopic level scientific knowledge acquired through formal instruction into students' initial macroscopic knowledge frameworks.

Residual thermal stress control in composite reinforced metal structures. [by mechanical loading of metal component prior to bonding

NASA Technical Reports Server (NTRS)

Kelly, J. B.; June, R. R.

1972-01-01

Advanced composite materials, composed of boron or graphite fibers and a supporting matrix, make significant structural efficiency improvements available to aircraft and aerospace designers. Residual stress induced during bonding of composite reinforcement to metal structural elements can be reduced or eliminated through suitable modification to the manufacturing processes. The most successful method employed during this program used a steel tool capable of mechanically loading the metal component in compression prior to the adhesive bonding cycle. Compression loading combined with heating to 350 F during the bond cycle can result in creep deformation in aluminum components. The magnitude of the deformation increases with increasing stress level during exposure to 350 F.

Mineralogy at Meridiani Planum from the Mini-TES experiment on the opportunity rover

USGS Publications Warehouse

Christensen, P.R.; Wyatt, M.B.; Glotch, T.D.; Rogers, A.D.; Anwar, S.; Arvidson, R. E.; Bandfield, J.L.; Blaney, D.L.; Budney, C.; Calvin, W.M.; Fallacaro, A.; Fergason, R.L.; Gorelick, N.; Graff, T.G.; Hamilton, V.E.; Hayes, A.G.; Johnson, J. R.; Knudson, A.T.; McSween, H.Y.; Mehall, G.L.; Mehall, L.K.; Moersch, J.E.; Morris, R.V.; Smith, M.D.; Squyres, S. W.; Ruff, S.W.; Wolff, M.J.

2004-01-01

The Miniature Thermal Emission Spectrometer (Mini-TES) on Opportunity investigated the mineral abundances and compositions of outcrops, rocks, and soils at Meridiani Planum. Coarse crystalline hematite and olivine-rich basaltic sands were observed as predicted from orbital TES spectroscopy. Outcrops of aqueous origin are composed of 15 to 35% by volume magnesium and calcium sulfates [a high-silica component modeled as a combination of glass, feldspar, and sheet silicates (???20 to 30%)], and hematite; only minor jarosite is identified in Mini-TES spectra. Mini-TES spectra show only a hematite signature in the millimeter-sized spherules. Basaltic materials have more plagioclase than pyroxene, contain olivine, and are similar in inferred mineral composition to basalt mapped from orbit. Bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites. Bright wind streak material matches global dust. Waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering.

The Effects of Foam Thermal Protection System on the Damage Tolerance Characteristics of Composite Sandwich Structures for Launch Vehicles

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Hodge, A. J.; Jackson, J. R.

2011-01-01

For any structure composed of laminated composite materials, impact damage is one of the greatest risks and therefore most widely tested responses. Typically, impact damage testing and analysis assumes that a solid object comes into contact with the bare surface of the laminate (the outer ply). However, most launch vehicle structures will have a thermal protection system (TPS) covering the structure for the majority of its life. Thus, the impact response of the material with the TPS covering is the impact scenario of interest. In this study, laminates representative of the composite interstage structure for the Ares I launch vehicle were impact tested with and without the planned TPS covering, which consists of polyurethane foam. Response variables examined include maximum load of impact, damage size as detected by nondestructive evaluation techniques, and damage morphology and compression after impact strength. Results show that there is little difference between TPS covered and bare specimens, except the residual strength data is higher for TPS covered specimens.

Self-assembly of nanocomposite materials

DOEpatents

Brinker, C. Jeffrey; Sellinger, Alan; Lu, Yunfeng

2001-01-01

A method of making a nanocomposite self-assembly is provided where at least one hydrophilic compound, at least one hydrophobic compound, and at least one amphiphilic surfactant are mixed in an aqueous solvent with the solvent subsequently evaporated to form a self-assembled liquid crystalline mesophase material. Upon polymerization of the hydrophilic and hydrophobic compounds, a robust nanocomposite self-assembled material is formed. Importantly, in the reaction mixture, the amphiphilic surfactant has an initial concentration below the critical micelle concentration to allow formation of the liquid-phase micellar mesophase material. A variety of nanocomposite structures can be formed, depending upon the solvent evaporazation process, including layered mesophases, tubular mesophases, and a hierarchical composite coating composed of an isotropic worm-like micellar overlayer bonded to an oriented, nanolaminated underlayer.

Marginal adaptation of composite resins under two adhesive techniques.

PubMed

Dačić, Stefan; Veselinović, Aleksandar M; Mitić, Aleksandar; Nikolić, Marija; Cenić, Milica; Dačić-Simonović, Dragica

2016-11-01

In the present research, different adhesive techniques were used to set up fillings with composite resins. After the application of etch and rinse or self etch adhesive technique, marginal adaptation of composite fillings was estimated by the length of margins without gaps, and by the microretention of resin in enamel and dentin. The study material consisted of 40 extracted teeth. Twenty Class V cavities were treated with 35% phosphorous acid and restored after rinsing by Adper Single Bond 2 and Filtek Ultimate-ASB/FU 3M ESPE composite system. The remaining 20 cavities were restored by Adper Easy One-AEO/FU 3M ESPE composite system. Marginal adaptation of composite fillings was examined using a scanning electron microscope (SEM). The etch and rinse adhesive technique showed a significantly higher percentage of margin length without gaps (in enamel: 92.5%, in dentin: 57.3%), compared with the self-etch technique with lower percentage of margin length without gaps, in enamel 70.4% (p < .001), and in dentin-22.6% (p < .05). In the first technique, microretention was composed of adhesive and hybrid layers as well as resin tugs in interprismatic spaces of enamel, while the dentin microretention was composed of adhesive and hybrid layers with resin tugs in dentin canals. In the second technique, resin tugs were rarely seen and a microgap was dominant along the border of restoration margins. The SEM analysis showed a better marginal adaptation of composite resin to enamel and dentin with better microretention when the etch and rinse adhesive procedure was applied. © 2016 Wiley Periodicals, Inc.

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

Zhang, Junsong; Liu, Yinong; Huan, Yong

The concept of transformation-induced plasticity effect is introduced in this work to improve the plasticity of brittle intermetallic compound Ti3Sn, which is a potent high damping material. This concept is achieved in an in situ NiTi/Ti3Sn composite. The composite is composed of primary Ti3Sn phase and (NiTi + Ti3Sn) eutectic structure formed via hypereutectic solidification. The composite exhibits a high damping capacity of 0.075 (indexed by tan δ), a high ultimate compressive strength of 1350 MPa, and a large plasticity of 27.5%. In situ synchrotron high-energy X-ray diffraction measurements revealed clear evidence of the stress-induced martensitic transformation (B2 → B19)more » of the NiTi component during deformation. The strength of the composite mainly stems from the Ti3Sn, whereas the NiTi component is responsible for the excellent plasticity of the composite.« less

Development of a Subcell Based Modeling Approach for Modeling the Architecturally Dependent Impact Response of Triaxially Braided Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Sorini, Chris; Chattopadhyay, Aditi; Goldberg, Robert K.; Kohlman, Lee W.

2016-01-01

Understanding the high velocity impact response of polymer matrix composites with complex architectures is critical to many aerospace applications, including engine fan blade containment systems where the structure must be able to completely contain fan blades in the event of a blade-out. Despite the benefits offered by these materials, the complex nature of textile composites presents a significant challenge for the prediction of deformation and damage under both quasi-static and impact loading conditions. The relatively large mesoscale repeating unit cell (in comparison to the size of structural components) causes the material to behave like a structure rather than a homogeneous material. Impact experiments conducted at NASA Glenn Research Center have shown the damage patterns to be a function of the underlying material architecture. Traditional computational techniques that involve modeling these materials using smeared homogeneous, orthotropic material properties at the macroscale result in simulated damage patterns that are a function of the structural geometry, but not the material architecture. In order to preserve heterogeneity at the highest length scale in a robust yet computationally efficient manner, and capture the architecturally dependent damage patterns, a previously-developed subcell modeling approach where the braided composite unit cell is approximated as a series of four adjacent laminated composites is utilized. This work discusses the implementation of the subcell methodology into the commercial transient dynamic finite element code LS-DYNA (Livermore Software Technology Corp.). Verification and validation studies are also presented, including simulation of the tensile response of straight-sided and notched quasi-static coupons composed of a T700/PR520 triaxially braided [0deg/60deg/-60deg] composite. Based on the results of the verification and validation studies, advantages and limitations of the methodology as well as plans for future work are discussed.

Colloidal Synthesis of Silicon-Carbon Composite Material for Lithium-Ion Batteries.

PubMed

Su, Haiping; Barragan, Alejandro A; Geng, Linxiao; Long, Donghui; Ling, Licheng; Bozhilov, Krassimir N; Mangolini, Lorenzo; Guo, Juchen

2017-08-28

We report colloidal routes to synthesize silicon@carbon composites for the first time. Surface-functionalized Si nanoparticles (SiNPs) dissolved in styrene and hexadecane are used as the dispersed phase in oil-in-water emulsions, from which yolk-shell and dual-shell hollow SiNPs@C composites are produced via polymerization and subsequent carbonization. As anode materials for Li-ion batteries, the SiNPs@C composites demonstrate excellent cycling stability and rate performance, which is ascribed to the uniform distribution of SiNPs within the carbon hosts. The Li-ion anodes composed of 46 wt % of dual-shell SiNPs@C, 46 wt % of graphite, 5 wt % of acetylene black, and 3 wt % of carboxymethyl cellulose with an areal loading higher than 3 mg cm -2 achieve an overall specific capacity higher than 600 mAh g -1 , which is an improvement of more than 100 % compared to the pure graphite anode. These new colloidal routes present a promising general method to produce viable Si-C composites for Li-ion batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bioinspired Hierarchical Nanofibrous Silver-Nanoparticle/Anatase-Rutile-Titania Composite as an Anode Material for Lithium-Ion Batteries.

PubMed

Luo, Yan; Li, Jiao; Huang, Jianguo

2016-11-29

A new bioinspired hierarchical nanofibrous silver-nanoparticle/anatase-rutile-titania (Ag-NP/A-R-titania) composite was fabricated by employing a natural cellulose substance (e.g., commercial laboratory cellulose filter paper) as the structural scaffold template, which was composed of anatase-phase titania (A-titania) nanotubes with rutile-phase titania (R-titania) nanoneedles grown on the surfaces and further silver nanoparticles (AgNPs) immobilized thereon. As it was employed as an anode material for lithium-ion batteries (LIBs), high reversible capacity, enhanced rate performance, and excellent cycling stability were achieved as compared with those of the corresponding cellulose-substance-derived nanotubular A-titania, R-titania, heterogeneous anatase/rutile titania (A-R-titania) composite, and commercial P25 powder. This benefited from its unique porous cross-linked three-dimensional structure inherited from the initial cellulose substance scaffold, which enhances the sufficient electrode/electrolyte contact, relieves the severe volume change upon cycling, and improves the amount of lithium-ion storage; moreover, the high loading content of the silver component in the composite improves the electrical conductivity of the electrode. The structural integrity of the composite was maintained upon long-term charge/discharge cycling, indicating its significant stability.

Mechanical strength and thermophysical properties of PM212: A high temperature self-lubricating powder metallurgy composite

NASA Technical Reports Server (NTRS)

Edwards, Phillip M.; Sliney, Harold E.; Dellacorte, Christopher; Whittenberger, J. Daniel; Martineau, Robert R.

1990-01-01

A powder metallurgy composite, PM212, composed of metal bonded chromium carbide and solid lubricants is shown to be self-lubricating to a maximum application temperature of 900 C. The high temperature compressive strength, tensile strength, thermal expansion and thermal conductivity data needed to design PM212 sliding contact bearings and seals are reported for sintered and isostatically pressed (HIPed) versions of PM212. Other properties presented are room temperature density, hardness, and elastic modulus. In general, both versions appear to have adequate strength to be considered as sliding contact bearing materials, but the HIPed version, which is fully dense, is much stronger than the sintered version which contains about 20 percent pore volume. The sintered material is less costly to make, but the HIPed version is better where high compressive strength is important.

Selective Clay Placement within a Silicate Clay-Epoxy Blend Nanocomposite and the Effect on Physical Properties

NASA Technical Reports Server (NTRS)

Miller, Sandi G.; Scheiman, Daniel A; Kohlmman, Lee W.

2009-01-01

Many epoxy systems under consideration for composite pressure vessels are composed of toughened epoxy resins. In this work, epoxy blends containing both rigid aromatic and flexible aliphatic components were prepared, to model toughened systems, and determine the optimum route of silicate addition. Compositions were chosen such that both glassy and rubbery resins were obtained at room temperature. The physical properties of the nanocomposites varied with T(g) and silicate placement, however, nanocomposite T(g)s were observed which exceeded that of the base resin by greater than 10 C. The tensile strength of the glassy resin remained constant or decreased on the dispersion of clay while that of the rubbery material doubled. Selectively placing the clay in the aliphatic component of the rubbery blend resulted in a greater than 100% increase in material toughness.

The Preparation of Soft Magnetic Composites Based on FeSi and Ferrite Fibers

NASA Astrophysics Data System (ADS)

Strečková, Magdaléna; Fáberová, Mária; Bureš, Radovan; Kurek, Pavel

2016-12-01

The fields of soft magnetic composites and powder metallurgy technologies have a powerful potential to redesign the way of electric motor preparation, and will continue to grow for years to come. A design of the novel soft microcomposite material composed of spherical FeSi particles and Ni0.3Zn0.7Fe2O4 ferrite nanofibers is reported together with a characterization of basic mechanical and electrical properties. The needle-less electrospinning method was used for a preparation of Ni0.3Zn0.7Fe2O4 ferrite nanofibers, which has a spinel-type crystal structure as verified by XRD and TEM analysis. The dielectric coating was prepared by mixing of nanofibers with glycerol and ethanol because of safe manipulation with fumed fibers and homogeneous distribution of the coating around the FeSi particle surface. The final microcomposite samples were prepared by a combination of the traditional PM compaction technique supplemented with a conventional sintering process of the prepared green compacts. The composition and distribution of the secondary phase formed by the spinel ferrite fibers were examined by SEM. It is demonstrated that the prepared composite material has a tight arrangement without any significant porosity, which manifest itself through superior mechanical properties (high mechanical hardness, Young modulus, and transverse rupture strength) and specific electric resistivity compared to the related composite materials including resin as the organic binder.

Atmospheric Circulation and Composition of GJ1214b

NASA Astrophysics Data System (ADS)

Menou, Kristen

2012-01-01

The exoplanet GJ1214b presents an interesting example of compositional degeneracy for low-mass planets. Its atmosphere may be composed of water, super-solar or solar metallicity material. We present atmospheric circulation models of GJ1214b for these three compositions, with explicit gray radiative transfer and an optional treatment of MHD bottom drag. All models develop strong, superrotating zonal winds (~1-2 km s-1). The degree of eastward heat advection, which can be inferred from secondary eclipse and thermal phase curve measurements, varies greatly between the models. These differences are understood as resulting from variations in the radiative times at the thermal photosphere, caused by separate molecular weight and opacity effects. Our GJ1214b models illustrate how atmospheric circulation can be used as a probe of composition for similar tidally locked exoplanets in the mini-Neptune/waterworld class.

Polypyrrole/carbon nanotube supercapacitors: Technological advances and challenges

NASA Astrophysics Data System (ADS)

Afzal, Adeel; Abuilaiwi, Faraj A.; Habib, Amir; Awais, Muhammad; Waje, Samaila B.; Atieh, Muataz A.

2017-06-01

The supercapacitors are advanced electrochemical energy storage devices having characteristics such as high storage capacity, rapid delivery of charge, and long cycle life. Polypyrrole (PPy) - an electronically conducting polymer, and carbon nanotubes (CNT) with high surface area and exceptional electrical and mechanical properties are among the most frequently studied advanced electrode materials for supercapacitors. The asymmetric supercapacitors composed of PPy/CNT composite electrodes offer complementary benefits to improve the specific capacitance, energy density, and stability. This article presents an overview of the recent technological advances in PPy/CNT composite supercapacitors and their limitations. Various strategies for synthesis and fabrication of PPy/CNT composites are discussed along with the factors that influence their ultimate electrochemical performance. The drawbacks and challenges of modern PPy/CNT composite supercapacitors are also reviewed, and potential areas of concern are identified for future research and development.

Modeling of Failure for Analysis of Triaxial Braided Carbon Fiber Composites

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Littell, Justin D.; Binienda, Wieslaw K.

2010-01-01

In the development of advanced aircraft-engine fan cases and containment systems, composite materials are beginning to be used due to their low weight and high strength. The design of these structures must include the capability of withstanding impact loads from a released fan blade. Relatively complex triaxially braided fiber architectures have been found to yield the best performance for the fan cases. To properly work with and design these structures, robust analytical tools are required that can be used in the design process. A new analytical approach models triaxially braided carbon fiber composite materials within the environment of a transient dynamic finite-element code, specifically the commercially available transient dynamic finite-element code LS-DYNA. The geometry of the braided composites is approximated by a series of parallel laminated composites. The composite is modeled by using shell finite elements. The material property data are computed by examining test data from static tests on braided composites, where optical strain measurement techniques are used to examine the local strain variations within the material. These local strain data from the braided composite tests are used along with a judicious application of composite micromechanics- based methods to compute the stiffness properties of an equivalent unidirectional laminated composite required for the shell elements. The local strain data from the braided composite tests are also applied to back out strength and failure properties of the equivalent unidirectional composite. The properties utilized are geared towards the application of a continuum damage mechanics-based composite constitutive model available within LS-DYNA. The developed model can be applied to conduct impact simulations of structures composed of triaxially braided composites. The advantage of this technology is that it facilitates the analysis of the deformation and damage response of a triaxially braided polymer matrix composite within the environment of a transient dynamic finite-element code such as LS-DYNA in a manner which accounts for the local physical mechanisms but is still computationally efficient. This methodology is tightly coupled to experimental tests on the braided composite, which ensures that the material properties have physical significance. Aerospace or automotive companies interested in using triaxially braided composites in their structures, particularly for impact or crash applications, would find the technology useful. By the development of improved design tools, the amount of very expensive impact testing that will need to be performed can be significantly reduced.

Metallic elements occurrences within metallic fragments in the municipal waste incineration bottom ash

NASA Astrophysics Data System (ADS)

Kowalski, Piotr; Kasina, Monika; Michalik, Marek

2017-04-01

Bottom ash (BA) from municipal solid waste incineration (MSWI) is composed of grainy ash material, residual components and metallic fragments (from few µm up to 3-5 cm). Its mineral and chemical composition is related to the composition of the waste stream in the incinerator operational area. Wide use of thermal techniques in management of solid waste makes important the studies on valuable components and their distribution within the material in terms of their further processing. By using various valorization or extraction techniques it is possible to extend the range of its possible further application. To investigate metallic elements distribution within metallic fragments of the MSWI BA material produced in municipal waste incineration plant in Poland were collected in 2015 and 2016. BA and its components were investigated using spectroscopic methods of chemical analysis: ICP-OES, ICP-MS, LECO and EDS (used for microanalysis during SEM observations). BA is a material rich in Si (22.5 wt%), Ca (13.4 wt%), Fe (4 wt%), Al (5.2 wt%) and Na (3.5 wt%), composed of equal part of amorphous (silicate glass dominated) and crystalline phase (rich in silicates, aluminosilicates, oxides of non- and metallic elements and sulphates). The content of metallic elements (Al, Fe, Mg, Ti, Mn, Cr, Ni, Sc, Mo, Cu, Pb, Zn, Sn) is 11.5 wt% with domination of Al (5.2 wt%) and Fe (4 wt%) and elevated values of Mg (1 wt%), Ti (0.54 wt%), Cu (0.26 wt%) and Zn (0.27 wt%) (Kowalski et al., 2016). They were mostly concentrated in the form of metallic fragments, mainly as metallic inclusions in the size of 1-20 µm and separated metallic grains in the size of 50-300 µm. Metallic fragments present in the BA are characterized by their composition heterogeneity and various oxygen content. Fragments are rarely composed of single metallic element and usually in their composition up to few main elements dominated over others. The most common were Fe-, Al- and Zn-rich fragments forming respectively 70%, 15% and 5% of the total amount of fragments. Fe occurred mainly as component of metallic inclusions and separate grains. Al was mostly present in metallic fragments on grains boundaries and also and as separate grains (often oxidised), moreover Al was important component of aluminosilicates and amorphous phase. Zn-rich metallic fragments were mostly in the form of separate grains. In complex composition of metallic fragments some regularities in elements co-occurrences were observed: Fe often co-existed with Si, Ca, P, Al and Ti; Al co-occurred with Fe, Si and Ca; Zn co-existed with Ca, Al and Si. Forms and composition of metallic fragments allows to evaluate them as potential polymetallic resource, however an economically reasonable extraction techniques must be applied. Acknowledgment Research was funded by Polish National Science Centre (NCN). Scientific grant No. UMO-2014/15/B/ST10/04171. Reference Kowalski, P.R., Kasina, M. and Michalik M.: Metallic elements fractionation in municipal solid waste incineration residues, Energy Procedia, 97, 31-36, doi: 10.1016/j.egypro.2016.10.013, 2016.

Nanostructured Thermal Protection Systems for Space Exploration Missions

NASA Technical Reports Server (NTRS)

Arnold, J. O.; Chen, Y. K.; Squire, T.; Srivastava, D.; Allen, G., Jr.; Stackpoole, M.; Goldstein, H. E.; Venkatapathy, E.; Loomis, M. P.

2005-01-01

Strong research and development programs in nanotechnology and Thermal Protection Systems (TPS) exist at NASA Ames. Conceptual studies have been undertaken to determine if new, nanostructured materials (composites of existing TPS materials and nanostructured composite fibers) could improve the performance of TPS. To this end, we have studied various candidate heatshields, some composed of existing TPS materials (with known material properties), to provide a baseline for comparison with others that are admixtures of such materials and a nanostructured material. In the latter case, some assumptions were made about the thermal conductivity and strength of the admixture, relative to the baseline TPS material. For the purposes of this study, we have made the conservative assumption that only a small fraction of the remarkable properties of carbon nanotubes (for example) will be realized in the material properties of the admixtures employing them. The heatshields studied included those for Sharp leading edges (appropriate to out-of-orbit entry and aero-maneuvering), probes, an out-of-orbit Apollo Command Module (as a surrogate for NASA's new Crew Exploration Vehicle [CEV]), a Mars Sample Return Vehicle and a large heat shield for Mars aerocapture missions. We report on these conceptual studies, which show that in some cases (not all), significant improvements in the TPS can be achieved through the use of nanostructured materials.

Improved corrosion resistance on biodegradable magnesium by zinc and aluminum ion implantation

NASA Astrophysics Data System (ADS)

Xu, Ruizhen; Yang, Xiongbo; Suen, Kai Wong; Wu, Guosong; Li, Penghui; Chu, Paul K.

2012-12-01

Magnesium and its alloys have promising applications as biodegradable materials, and plasma ion implantation can enhance the corrosion resistance by modifying the surface composition. In this study, suitable amounts of zinc and aluminum are plasma-implanted into pure magnesium. The surface composition, phases, and chemical states are determined, and electrochemical tests and electrochemical impedance spectroscopy (EIS) are conducted to investigate the surface corrosion behavior and elucidate the mechanism. The corrosion resistance enhancement after ion implantation is believed to stem from the more compact oxide film composed of magnesium oxide and aluminum oxide as well as the appearance of the β-Mg17Al12 phase.

The Candida albicans Biofilm Matrix: Composition, Structure and Function.

PubMed

Pierce, Christopher G; Vila, Taissa; Romo, Jesus A; Montelongo-Jauregui, Daniel; Wall, Gina; Ramasubramanian, Anand; Lopez-Ribot, Jose L

2017-03-01

A majority of infections caused by Candida albicans -the most frequent fungal pathogen-are associated with biofilm formation. A salient feature of C. albicans biofilms is the presence of the biofilm matrix. This matrix is composed of exopolymeric materials secreted by sessile cells within the biofilm, in which all classes of macromolecules are represented, and provides protection against environmental challenges. In this review, we summarize the knowledge accumulated during the last two decades on the composition, structure, and function of the C. albicans biofilm matrix. Knowledge of the matrix components, its structure, and function will help pave the way to novel strategies to combat C. albicans biofilm infections.

The Candida albicans Biofilm Matrix: Composition, Structure and Function

PubMed Central

Pierce, Christopher G.; Vila, Taissa; Romo, Jesus A.; Montelongo-Jauregui, Daniel; Wall, Gina; Ramasubramanian, Anand; Lopez-Ribot, Jose L.

2017-01-01

A majority of infections caused by Candida albicans—the most frequent fungal pathogen—are associated with biofilm formation. A salient feature of C. albicans biofilms is the presence of the biofilm matrix. This matrix is composed of exopolymeric materials secreted by sessile cells within the biofilm, in which all classes of macromolecules are represented, and provides protection against environmental challenges. In this review, we summarize the knowledge accumulated during the last two decades on the composition, structure, and function of the C. albicans biofilm matrix. Knowledge of the matrix components, its structure, and function will help pave the way to novel strategies to combat C. albicans biofilm infections. PMID:28516088

Electrostatic Discharge Sensitivity and Electrical Conductivity of Composite Energetic Materials

DTIC Science & Technology

2013-02-01

intermetallic) [13,14], a metal oxide ( thermite ) [13e15], or a fluoropolymer [16,17]. They can be used as additives in explosives to decrease...research on ESD ignition sensitivity of thermites and intermetallics. Because thermites are composed of particulate media and widely used, they pose a... thermites and intermetallics for pyrotechnic applications, in: 32nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 1996. [15] K.W. Watson, M.L

Compression response of thick layer composite laminates with through-the-thickness reinforcement

NASA Technical Reports Server (NTRS)

Farley, Gary L.; Smith, Barry T.; Maiden, Janice

1992-01-01

Compression and compression-after-impact (CAI) tests were conducted on seven different AS4-3501-6 (0/90) 0.64-cm thick composite laminates. Four of the seven laminates had through-the-thickness (TTT) reinforcement fibers. Two TTT reinforcement methods, stitching and integral weaving, and two reinforcement fibers, Kevlar and carbon, were used. The remaining three laminates were made without TTT reinforcements and were tested to establish a baseline for comparison with the laminates having TTT reinforcement. Six of the seven laminates consisted of nine thick layers whereas the seventh material was composed of 46 thin plies. The use of thick-layer material has the potential for reducing structural part cost because of the reduced part count (layers of material). The compression strengths of the TTT reinforced laminates were approximately one half those of the materials without TTT reinforcements. However, the CAI strengths of the TTT reinforced materials were approximately twice those of materials without TTT reinforcements. The improvement in CAI strength is due to an increase in interlaminar strength produced by the TTT reinforcement. Stitched laminates had slightly higher compression and CAI strengths than the integrally woven laminates.

Composing for Digital Publication: Rhetoric, Design, Code

ERIC Educational Resources Information Center

Eyman, Douglas; Ball, Cheryl E.

2014-01-01

The authors discuss the state of digital publication with the claim that, at this historical moment, nearly all composition is digital composition. But, as a field, composition studies has not yet made that shift completely explicit in the discussions of composing processes and writing pedagogies. A deeper engagement with this very rapid shift in…

Constraints on the nanoscale minerals on the surface of Saturnian icy moons

NASA Astrophysics Data System (ADS)

Srama, R.; Hsu, H.; Kempf, S.; Horanyi, M.

2011-12-01

Nano-phase iron particles embedded into the surfaces of Saturn's icy moons as well as in the ring material have been proposed to explain the infrared spectra obtained by Cassini VIMS. Because the continuous influx of interplanetary fast impactors into the Saturnian system erodes any exposed surface, a certain amount of the embedded nano-particles will be ejected into the Saturnian magnetosphere and speed up to velocities high enough to be detected by the Cassini dust detector CDA. Thus, the analysis of the so-called stream particles provides constraints on the amount and the composition of any nano-phase material within the surfaces of the icy moons. Nanoparticles registered by the Cassini dust detector are most likely composed of silica (SiO2). Their dynamical properties indicate that they are relics of E ring dust grains. In this talk we will show that the Cassini stream particle measurements provide strong constraints for the composition and size distribution of any embedded nano-material.

Three-dimensional analysis of anisotropic spatially reinforced structures

NASA Technical Reports Server (NTRS)

Bogdanovich, Alexander E.

1993-01-01

The material-adaptive three-dimensional analysis of inhomogeneous structures based on the meso-volume concept and application of deficient spline functions for displacement approximations is proposed. The general methodology is demonstrated on the example of a brick-type mosaic parallelepiped arbitrarily composed of anisotropic meso-volumes. A partition of each meso-volume into sub-elements, application of deficient spline functions for a local approximation of displacements and, finally, the use of the variational principle allows one to obtain displacements, strains, and stresses at anypoint within the structural part. All of the necessary external and internal boundary conditions (including the conditions of continuity of transverse stresses at interfaces between adjacent meso-volumes) can be satisfied with requisite accuracy by increasing the density of the sub-element mesh. The application of the methodology to textile composite materials is described. Several numerical examples for woven and braided rectangular composite plates and stiffened panels under transverse bending are considered. Some typical effects of stress concentrations due to the material inhomogeneities are demonstrated.

Characterization of morphology and composition of inorganic fillers in dental alginates.

PubMed

Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

2014-01-01

Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450(°)C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C-81.59%, H-79.89%, O-78.87%, H5-77.95%, JP-66.88%, wt). The filler fractions in volume (vt) were as follows: H5-84.85%, JP-74.76%, H-70.03%, O-68.31%, and C-56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology.

Third-generation pure alumina and alumina matrix composites in total hip arthroplasty: What is the evidence?

PubMed

Hannouche, Didier; Zingg, Matthieu; Miozzari, Hermes; Nizard, Remy; Lübbeke, Anne

2018-01-01

Wear, corrosion and periprosthetic osteolysis are important causes of failure in joint arthroplasty, especially in young patients.Ceramic bearings, developed 40 years ago, are an increasingly popular choice in hip arthroplasty. New manufacturing procedures have increased the strength and reliability of ceramic materials and reduced the risk of complications.In recent decades, ceramics made of pure alumina have continuously improved, resulting in a surgical-grade material that fulfills clinical requirements.Despite the track record of safety and long-term results, third-generation pure alumina ceramics are being replaced in clinical practice by alumina matrix composites, which are composed of alumina and zirconium.In this review, the characteristics of both materials are discussed, and the long-term results with third-generation alumina-on-alumina bearings and the associated complications are compared with those of other available ceramics. Cite this article: EFORT Open Rev 2018;3:7-14. DOI: 10.1302/2058-5241.3.170034.

Effects of material composition on the ablation performance of low density elastomeric ablators

NASA Technical Reports Server (NTRS)

Tompkins, S. S.; Kabana, W. P.

1973-01-01

The ablation performance of materials composed of various concentrations of nylon, hollow silica spheres, hollow phenolic spheres, and four elastomeric resins was determined. Both blunt-body and flat-panel specimens were used, the cold-wall heating-rate ranges being 0.11 to 0.8 MW/sq m, respectively. The corresponding surface pressure ranges for these tests were 0.017 to 0.037 atmosphere and 0.004 to 0.005 atmosphere. Some of the results show that (1) the addition of nylon significantly improved the ablation performance, but the nylon was not compatible with one resin system; (2) panel and blunt-body specimen data do not show the same effect of phenolic sphere content on ablation effectiveness; and (3) there appears to be an optimum concentration of hollow silica spheres for good ablation performance. The composition of an efficient, nonproprietary ablator for lifting body application is identified and the ablation performance of this ablator is compared with the performance of three commercially available materials.

Realizing Crack Diagnosing and Self‐Healing by Electricity with a Dynamic Crosslinked Flexible Polyurethane Composite

PubMed Central

Pu, Wuli; Fu, Daihua; Wang, Zhanhua; Gan, Xinpeng; Lu, Xili; Yang, Li

2018-01-01

Abstract Combining self‐healing functions with damage diagnosing, which can achieve timely healing autonomously, is expected to improve the reliability and reduce life cycle cost of materials. Here, a flexible conductive composite composed of a dynamically crosslinked polyurethane bearing Diels–Alder bonds (PUDA) and carbon nanotubes (CNTs), which possess both crack diagnosing and self‐healing functions, is reported. The introduced dynamic Diels–Alder bonds endow the materials self‐healing function and the powder‐based preparation route based on the specially designed CNTs‐coated PUDA micropowders leads to the formation of segregated CNTs network, which makes the composite possess excellent mechanical properties and high conductivity. Because of the sufficient electrothermal and photothermal effect of CNTs, the composites can be healed rapidly and repeatedly by electricity or near‐infrared light based on the retro‐Diels–Alder reaction. An obvious color difference in the infrared thermograph resulting from the resistance difference between damaged and undamaged area can be observed when applying the voltage, which can be used for crack diagnosing. Using the same electrical circuit, the crack in the PUDA/CNTs composite can be noninvasively detected first and then be autonomously healed. The composites also exhibit a strain‐sensing function with good sensitivity and high reliability, thus will have potential applications in electronic strain sensors. PMID:29876226

Genesis of Augite-Bearing Ureilites: Evidence From LA-ICP-MS Analyses of Pyroxenes and Olivine

NASA Technical Reports Server (NTRS)

Herrin, J. S.; Lee, C-T. A.; Mittlefehldt, D. W.

2008-01-01

Ureilites are ultramafic achondrites composed primarily of coarse-grained low-Ca pyroxene and olivine with interstitial carbonaceous material, but a number of them contain augite [1]. Ureilites are considered to be restites after partial melting of a chondritic precursor, although at least some augite-bearing ureilites may be partially cumulate [1, 2]. In this scenario, the augite is a cumulus phase derived from a melt that infiltrated a restite composed of typical ureilite material (olivine+low-Ca pyroxene) [2]. To test this hypothesis, we examined the major and trace element compositions of silicate minerals in select augite-bearing ureilites with differing mg#. Polished thick sections of the augite-bearing ureilites ALH 84136 , EET 87511, EET 96293, LEW 88201, and META78008 and augite-free typical ureilite EET 90019 were examined by EPMA for major and minor elements and laser ablation ICP-MS (LA-ICP-MS) for trace elements, REE in particular. Although EET 87511 is reported to contain augite, the polished section that we obtained did not.

Templated assembly of photoswitches significantly increases the energy-storage capacity of solar thermal fuels.

PubMed

Kucharski, Timothy J; Ferralis, Nicola; Kolpak, Alexie M; Zheng, Jennie O; Nocera, Daniel G; Grossman, Jeffrey C

2014-05-01

Large-scale utilization of solar-energy resources will require considerable advances in energy-storage technologies to meet ever-increasing global energy demands. Other than liquid fuels, existing energy-storage materials do not provide the requisite combination of high energy density, high stability, easy handling, transportability and low cost. New hybrid solar thermal fuels, composed of photoswitchable molecules on rigid, low-mass nanostructures, transcend the physical limitations of molecular solar thermal fuels by introducing local sterically constrained environments in which interactions between chromophores can be tuned. We demonstrate this principle of a hybrid solar thermal fuel using azobenzene-functionalized carbon nanotubes. We show that, on composite bundling, the amount of energy stored per azobenzene more than doubles from 58 to 120 kJ mol(-1), and the material also maintains robust cyclability and stability. Our results demonstrate that solar thermal fuels composed of molecule-nanostructure hybrids can exhibit significantly enhanced energy-storage capabilities through the generation of template-enforced steric strain.

Isolation of the Cell Wall.

PubMed

Canut, Hervé; Albenne, Cécile; Jamet, Elisabeth

2017-01-01

This chapter describes a method allowing the purification of the cell wall for studying both polysaccharides and proteins. The plant primary cell wall is mainly composed of polysaccharides (90-95 % in mass) and of proteins (5-10 %). At the end of growth, specialized cells may synthesize a lignified secondary wall composed of polysaccharides (about 65 %) and lignin (about 35 %). Due to its composition, the cell wall is the cellular compartment having the highest density and this property is used for its purification. It plays critical roles during plant development and in response to environmental constraints. It is largely used in the food and textile industries as well as for the production of bioenergy. All these characteristics and uses explain why its study as a true cell compartment is of high interest. The proposed method of purification can be used for large amount of material but can also be downscaled to 500 mg of fresh material. Tools for checking the quality of the cell wall preparation, such as protein analysis and microscopy observation, are also provided.

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.

New Flexible Silicone-Based EEG Dry Sensor Material Compositions Exhibiting Improvements in Lifespan, Conductivity, and Reliability

PubMed Central

Yu, Yi-Hsin; Chen, Shih-Hsun; Chang, Che-Lun; Lin, Chin-Teng; Hairston, W. David; Mrozek, Randy A.

2016-01-01

This study investigates alternative material compositions for flexible silicone-based dry electroencephalography (EEG) electrodes to improve the performance lifespan while maintaining high-fidelity transmission of EEG signals. Electrode materials were fabricated with varying concentrations of silver-coated silica and silver flakes to evaluate their electrical, mechanical, and EEG transmission performance. Scanning electron microscope (SEM) analysis of the initial electrode development identified some weak points in the sensors’ construction, including particle pull-out and ablation of the silver coating on the silica filler. The newly-developed sensor materials achieved significant improvement in EEG measurements while maintaining the advantages of previous silicone-based electrodes, including flexibility and non-toxicity. The experimental results indicated that the proposed electrodes maintained suitable performance even after exposure to temperature fluctuations, 85% relative humidity, and enhanced corrosion conditions demonstrating improvements in the environmental stability. Fabricated flat (forehead) and acicular (hairy sites) electrodes composed of the optimum identified formulation exhibited low impedance and reliable EEG measurement; some initial human experiments demonstrate the feasibility of using these silicone-based electrodes for typical lab data collection applications. PMID:27809260

New Flexible Silicone-Based EEG Dry Sensor Material Compositions Exhibiting Improvements in Lifespan, Conductivity, and Reliability.

PubMed

Yu, Yi-Hsin; Chen, Shih-Hsun; Chang, Che-Lun; Lin, Chin-Teng; Hairston, W David; Mrozek, Randy A

2016-10-31

This study investigates alternative material compositions for flexible silicone-based dry electroencephalography (EEG) electrodes to improve the performance lifespan while maintaining high-fidelity transmission of EEG signals. Electrode materials were fabricated with varying concentrations of silver-coated silica and silver flakes to evaluate their electrical, mechanical, and EEG transmission performance. Scanning electron microscope (SEM) analysis of the initial electrode development identified some weak points in the sensors' construction, including particle pull-out and ablation of the silver coating on the silica filler. The newly-developed sensor materials achieved significant improvement in EEG measurements while maintaining the advantages of previous silicone-based electrodes, including flexibility and non-toxicity. The experimental results indicated that the proposed electrodes maintained suitable performance even after exposure to temperature fluctuations, 85% relative humidity, and enhanced corrosion conditions demonstrating improvements in the environmental stability. Fabricated flat (forehead) and acicular (hairy sites) electrodes composed of the optimum identified formulation exhibited low impedance and reliable EEG measurement; some initial human experiments demonstrate the feasibility of using these silicone-based electrodes for typical lab data collection applications.

Elevated Temperature, Notched Compression Performance of Out of Autoclave Processed Composites

NASA Technical Reports Server (NTRS)

Grimsley, Brian W.; Sutter, James K.; Dixon, Genevieve D.; Smeltzer, Satn S.

2013-01-01

Curved honeycomb sandwich panels composed of carbon fiber reinforced toughened-epoxy polymer facesheets are being evaluated for potential use as payload fairing components on the NASA heavy-lift space launch system (HL-SLS). These proposed composite sandwich panels provide the most efficient aerospace launch structures, and offer mass and thermal advantages when compared with existing metallic payload fairing structures. NASA and industry are investigating recently developed carbon fiber epoxy prepreg systems which can be fabricated using out-of autoclave (OOA) processes. Specifically, OOA processes using vacuum pressure in an oven and thereby significantly reducing the cost associated with manufacturing large (up to 10 m diameter) composite structures when compared with autoclave. One of these OOA composite material systems, CYCOM(R) 5320-1, was selected for manufacture of a 1/16th scale barrel portion of the payload fairing; such that, the system could be compared with the well-characterized prepreg system, CYCOM(R) 977-3, typically processed in an autoclave. Notched compression coupons for each material were obtained from the minimum-gauge flat laminate [60/-60/0]S witness panels produced in this manufacturing study. The coupons were also conditioned to an effective moisture equilibrium point and tested according to ASTM D6484M-09 at temperatures ranging from 25 C up to 177 C. The results of this elevated temperature mechanical characterization study demonstrate that, for thin coupons, the OHC strength of the OOA laminate was equivalent to the flight certified autoclave processed composite laminates; the limitations on the elevated temperature range are hot-wet conditions up to 163 C and are only within the margins of testing error. At 25 C, both the wet and dry OOA material coupons demonstrated greater OHC failure strengths than the autoclave processed material laminates. These results indicate a substantial improvement in OOA material development and processing since previous studies have consistently reported OOA material strengths on par or below those of autoclave processed composite laminates.

Incorporation of Damage and Failure into an Orthotropic Elasto-Plastic Three-Dimensional Model with Tabulated Input Suitable for Use in Composite Impact Problems

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Carney, Kelly S.; Dubois, Paul; Hoffarth, Canio; Khaled, Bilal; Rajan, Subramaniam; Blankenhorn, Gunther

2016-01-01

A material model which incorporates several key capabilities which have been identified by the aerospace community as lacking in the composite impact models currently available in LS-DYNA(Registered Trademark) is under development. In particular, the material model, which is being implemented as MAT 213 into a tailored version of LS-DYNA being jointly developed by the FAA and NASA, incorporates both plasticity and damage within the material model, utilizes experimentally based tabulated input to define the evolution of plasticity and damage as opposed to specifying discrete input parameters (such as modulus and strength), and is able to analyze the response of composites composed with a variety of fiber architectures. The plasticity portion of the orthotropic, three-dimensional, macroscopic composite constitutive model is based on an extension of the Tsai-Wu composite failure model into a generalized yield function with a non-associative flow rule. The capability to account for the rate and temperature dependent deformation response of composites has also been incorporated into the material model. For the damage model, a strain equivalent formulation is utilized to allow for the uncoupling of the deformation and damage analyses. In the damage model, a diagonal damage tensor is defined to account for the directionally dependent variation of damage. However, in composites it has been found that loading in one direction can lead to damage in multiple coordinate directions. To account for this phenomena, the terms in the damage matrix are semi-coupled such that the damage in a particular coordinate direction is a function of the stresses and plastic strains in all of the coordinate directions. The onset of material failure, and thus element deletion, is being developed to be a function of the stresses and plastic strains in the various coordinate directions. Systematic procedures are being developed to generate the required input parameters based on the results of experimental tests.

Materials for engine applications above 3000 deg F: An overview

NASA Technical Reports Server (NTRS)

Shaw, Nancy J.; Dicarlo, James A.; Jacobson, Nathan S.; Levine, Stanley R.; Nesbitt, James A.; Probst, Hubert B.; Sanders, William A.; Stearns, Carl A.

1987-01-01

Materials for future generations of aeropropulsion systems will be required to perform at ever-increasing temperatures and have properties superior to the current state of the art. Improved engine efficiency can reduce specific fuel consumption and thus increase range and reduce operating costs. The ultimate payoff gain is expected to come when materials are developed which can perform without cooling at gas temperatures to 2200 C (4000 F). An overview is presented of materials for applications above 1650 C (3000 F), some pertinent physical property data, and the rationale used: (1) to arrive at recommendations of material systems that qualify for further investigation, and (2) to develop a proposed plan of research. From an analysis of available thermochemical data it was included that such materials systems must be composed of oxide ceramics. The required structural integrity will be achieved by developing these materials into fiber-reinforced ceramic composites.

Hybrid Surface Patterns Mimicking the Design of the Adhesive Toe Pad of Tree Frog.

PubMed

Xue, Longjian; Sanz, Belén; Luo, Aoyi; Turner, Kevin T; Wang, Xin; Tan, Di; Zhang, Rui; Du, Hang; Steinhart, Martin; Mijangos, Carmen; Guttmann, Markus; Kappl, Michael; Del Campo, Aránzazu

2017-10-24

Biological materials achieve directional reinforcement with oriented assemblies of anisotropic building blocks. One such example is the nanocomposite structure of keratinized epithelium on the toe pad of tree frogs, in which hexagonal arrays of (soft) epithelial cells are crossed by densely packed and oriented (hard) keratin nanofibrils. Here, a method is established to fabricate arrays of tree-frog-inspired composite micropatterns composed of polydimethylsiloxane (PDMS) micropillars embedded with polystyrene (PS) nanopillars. Adhesive and frictional studies of these synthetic materials reveal a benefit of the hierarchical and anisotropic design for both adhesion and friction, in particular, at high matrix-fiber interfacial strengths. The presence of PS nanopillars alters the stress distribution at the contact interface of micropillars and therefore enhances the adhesion and friction of the composite micropattern. The results suggest a design principle for bioinspired structural adhesives, especially for wet environments.

Hybrid Surface Patterns Mimicking the Design of the Adhesive Toe Pad of Tree Frog

PubMed Central

2017-01-01

Biological materials achieve directional reinforcement with oriented assemblies of anisotropic building blocks. One such example is the nanocomposite structure of keratinized epithelium on the toe pad of tree frogs, in which hexagonal arrays of (soft) epithelial cells are crossed by densely packed and oriented (hard) keratin nanofibrils. Here, a method is established to fabricate arrays of tree-frog-inspired composite micropatterns composed of polydimethylsiloxane (PDMS) micropillars embedded with polystyrene (PS) nanopillars. Adhesive and frictional studies of these synthetic materials reveal a benefit of the hierarchical and anisotropic design for both adhesion and friction, in particular, at high matrix–fiber interfacial strengths. The presence of PS nanopillars alters the stress distribution at the contact interface of micropillars and therefore enhances the adhesion and friction of the composite micropattern. The results suggest a design principle for bioinspired structural adhesives, especially for wet environments. PMID:28885831

Implanted neural network potentials: Application to Li-Si alloys

NASA Astrophysics Data System (ADS)

Onat, Berk; Cubuk, Ekin D.; Malone, Brad D.; Kaxiras, Efthimios

2018-03-01

Modeling the behavior of materials composed of elements with different bonding and electronic structure character for large spatial and temporal scales and over a large compositional range is a challenging problem. Cases in point are amorphous alloys of Si, a prototypical covalent material, and Li, a prototypical metal, which are being considered as anodes for high-energy-density batteries. To address this challenge, we develop a methodology based on neural networks that extends the conventional training approach to incorporate pre-trained parts that capture the character of different components, into the overall network; we refer to this model as the "implanted neural network" method. We show that this approach works well for the Si-Li amorphous alloys for a wide range of compositions, giving good results for key quantities like the diffusion coefficients. The method is readily generalizable to more complicated situations that involve two or more different elements.

Application of Carbon Composite Bricks for Blast Furnace Hearth

NASA Astrophysics Data System (ADS)

Zuo, Haibin; Wang, Cong; Zhang, Jianliang; Zhao, Yongan; Jiao, Kexin

Traditional refractory materials for blast furnace hearth lining are mainly composed of carbon bricks and the ceramic cup. However, these materials can't meet the demands for long service life design of blast furnaces. In this paper, a new refractory called carbon composite brick (CCB) was introduced, which combined the advantages of carbon bricks and the ceramic cup. In this case, the resistance of the CCB against corrosion was equal to the ceramic cup and the thermal conductivity of the CCB was equal to carbon bricks. From the results of more than 20 blast furnaces, the CCB could be well used in small blast furnaces and large blast furnaces. In the bad condition of low grade burden and high smelting intensity, the CCB gave full play to the role of cooling system, and effectively resisted the erosion of hot metal to improve the service life of blast furnaces.

Synthesis of Al4SiC4 powders from kaolin grog, aluminum and carbon black by carbothermal reaction

NASA Astrophysics Data System (ADS)

Yuan, Wenjie; Yu, Chao; Deng, Chengji; Zhu, Hongxi

2013-12-01

In this paper, the synthesis of Al4SiC4 used as natural oxide materials by carbothermal reduction was investigated in order to explore the synthesis route with low costs. The samples were calcined by using kaolin grog, aluminum and carbon black as raw materials with the selected proportion at the temperature from 1500 to 1800 ° C for 2 hours under flow argon atmosphere. The phase composition of reaction products were determined by X-ray diffraction. The microstructure and elemental composition of different phases were observed and identified by scanning electron microscopy and energy dispersive spectroscopy. The mechanism of reaction processing was discussed. The results show that Al4SiC4 powders composed of hexagonal plate-like particulates with various sizes and the thickness of less than 20 μm are obtained when the temperature reaches 1800 °C.

Demandite, lunar materials and space industrialization

NASA Technical Reports Server (NTRS)

Criswell, D. R.

1977-01-01

Terrestrial industry consumes a wide range of elements in producing the outputs which support and make industrial societies possible. 'Demandite' is a conceptual or synthetic molecule which is composed of the weight fractions of the major elements consumed by industry. Demandite needed for mature industrial activities in space will differ from the terrestrial composition because solar energy must replace hydrocarbon-energy, lunar and asteroidal bulk compositions are different from mineral deposits on the earth, and the major bulk processing in space will be the creation of radiation shielding for human habitats to provide real estate in space complete with water, atmosphere and life-stock elements. Demandite cost may be dominated by earth to deep space transport cost of minor elemental constituents depleted in the lunar soils unless careful attention is given to substitution of materials, searches of the moon (polar regions) and asteroids for the depleted elements, and continuing lowering of earth to deep space transport costs.

Molecular Spring Enabled High-Performance Anode for Lithium Ion Batteries

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

Zheng, Tianyue; Jia, Zhe; Lin, Na

Flexible butyl interconnection segments are synthetically incorporated into an electronically conductive poly(pyrene methacrylate) homopolymer and its copolymer. The insertion of butyl segment makes the pyrene polymer more flexible, and can better accommodate deformation. This new class of flexible and conductive polymers can be used as a polymer binder and adhesive to facilitate the electrochemical performance of a silicon/graphene composite anode material for lithium ion battery application. They act like a “spring” to maintain the electrode mechanical and electrical integrity. High mass loading and high areal capacity, which are critical design requirements of high energy batteries, have been achieved in themore » electrodes composed of the novel binders and silicon/graphene composite material. A remarkable area capacity of over 5 mAh/cm 2 and volumetric capacity of over 1700 Ah/L have been reached at a high current rate of 333 mA/g.« less

Molecular Spring Enabled High-Performance Anode for Lithium Ion Batteries

DOE PAGES

Zheng, Tianyue; Jia, Zhe; Lin, Na; ...

2017-11-29

Flexible butyl interconnection segments are synthetically incorporated into an electronically conductive poly(pyrene methacrylate) homopolymer and its copolymer. The insertion of butyl segment makes the pyrene polymer more flexible, and can better accommodate deformation. This new class of flexible and conductive polymers can be used as a polymer binder and adhesive to facilitate the electrochemical performance of a silicon/graphene composite anode material for lithium ion battery application. They act like a “spring” to maintain the electrode mechanical and electrical integrity. High mass loading and high areal capacity, which are critical design requirements of high energy batteries, have been achieved in themore » electrodes composed of the novel binders and silicon/graphene composite material. A remarkable area capacity of over 5 mAh/cm 2 and volumetric capacity of over 1700 Ah/L have been reached at a high current rate of 333 mA/g.« less

Large-area, near-infrared (IR) photonic crystals with colloidal gold nanoparticles embedding.

PubMed

Shukla, Shobha; Baev, Alexander; Jee, Hongsub; Hu, Rui; Burzynski, Ryszard; Yoon, Yong-Kyu; Prasad, Paras N

2010-04-01

A polymeric composite material composed of colloidal gold nanoparticles (<10 nm) and SU8 has been utilized for the fabrication of large-area, high-definition photonic crystal. We have successfully fabricated near-infrared photonic crystal slabs from composite materials using a combination of multiple beam interference lithography and reactive ion etching processes. Doping of colloidal gold nanoparticles into the SU8 photopolymer results in a better definition of structural features and hence in the enhancement of the optical properties of the fabricated photonic crystals. A 2D air hole array of triangular symmetry with a hole-to-hole pitch of approximately 500 nm has been successfully fabricated in a large circular area of 1 cm diameter. Resonant features observed in reflectance spectra of our slabs are found to depend on the exposure time, and can be tuned over a range of near-infrared frequencies.

Nondestructive Evaluation Techniques for Development and Characterization of Carbon Nanotube Based Superstructures

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Kim, Jae-Woo; Sauti, Godfrey; Wainwright, Elliot; Williams, Phillip; Siochi, Emile J.

2014-01-01

Recently, multiple commercial vendors have developed capability for the production of large-scale quantities of high-quality carbon nanotube sheets and yarns. While the materials have found use in electrical shielding applications, development of structural systems composed of a high volume fraction of carbon nanotubes is still lacking. A recent NASA program seeks to address this by prototyping a structural nanotube composite with strength-toweight ratio exceeding current state-of-the-art carbon fiber composites. Commercially available carbon nanotube sheets, tapes, and yarns are being processed into high volume fraction carbon nanotube-polymer nanocomposites. Nondestructive evaluation techniques have been applied throughout this development effort for material characterization and process control. This paper will report on the progress of these efforts, including magnetic characterization of residual catalyst content, Raman scattering characterization of nanotube diameter, defect ratio, and nanotube strain, and polarized Raman scattering for characterization of nanotube alignment.

Thermal inertia and radar reflectivity of the Martian north polar ERG: Low-density aggregates

NASA Technical Reports Server (NTRS)

Herkenhoff, K. E.

1993-01-01

The north polar layered deposits on Mars appear to be the source of the dark material that comprises the north polar erg. The physical properties and chemical composition of the erg material therefore have important implications for the origin and evolution of the Martian layered deposits. Viking bistatic radar and infrared thermal mapping (IRTM) data indicate that the bulk density of the erg material is lower than that of the average Martian surface. These data are consistent with hypotheses involving formation of filamentary sublimation residue (FSR) particles from erosion of the layered deposits. The color and albedo of the erg and of the layered deposits, and the presence of magnetic material on Mars, suggest that the dark material is composed of low-density aggregates of magnetic dust grains, perhaps similar to FSR particles created in laboratory experiments.

Assembly of Layered Monetite-Chitosan Nanocomposite and Its Transition to Organized Hydroxyapatite.

PubMed

Ruan, Qichao; Liberman, David; Zhang, Yuzheng; Ren, Dongni; Zhang, Yunpeng; Nutt, Steven; Moradian-Oldak, Janet

2016-06-13

Bioinspired synthesis of hierarchically structured calcium phosphate (CaP) material is a highly promising strategy for developing improved bone substitute materials. However, synthesis of CaP materials with outstanding mechanical properties still remains an ongoing challenge. Inspired by the formation of lamellar structure in nacre, we designed an organic matrix composed of chitosan and cis-butenediolic acid (maleic acid, MAc) that could assemble into a layered complex and further guide the mineralization of monetite crystals, resulting in the formation of organized and parallel arrays of monetite platelets with a brick-and-mortar structure. Using the layered monetite-chitosan composite as a precursor, we were able to synthesize hydroxyapatite (HAp) with multiscale hierarchically ordered structure via a topotactic phase transformation process. On the nanoscale, needlelike HAp crystallites assembled into organized bundles that aligned to form highly oriented plates on the microscale. On the large-scale level, these plates with different crystal orientations were stacked together to form a layered structure. The organized structures and composite feature yielded CaP materials with improved mechanical properties close to those of bone. Our study introduces a biomimetic approach that may be practical for the design of advanced, mechanically robust materials for biomedical applications.

A novel high specific surface area conducting paper material composed of polypyrrole and Cladophora cellulose.

PubMed

Mihranyan, Albert; Nyholm, Leif; Bennett, Alfonso E Garcia; Strømme, Maria

2008-10-02

We present a novel conducting polypyrrole-based composite material, obtained by polymerization of pyrrole in the presence of iron(III) chloride on a cellulose substrate derived from the environmentally polluting Cladophora sp. algae. The material, which was doped with chloride ions, was molded into paper sheets and characterized using scanning and transmission electron microscopy, N 2 gas adsorption analysis, cyclic voltammetry, chronoamperometry and conductivity measurements at varying relative humidities. The specific surface area of the composite was found to be 57 m (2)/g and the fibrous structure of the Cladophora cellulose remained intact even after a 50 nm thick layer of polypyrrole had been coated on the cellulose fibers. The composite could be repeatedly used for electrochemically controlled extraction and desorption of chloride and an ion exchanging capacity of 370 C per g of composite was obtained as a result of the high surface area of the cellulose substrate. The influence of the oxidation and reduction potentials on the chloride ion exchange capacity and the nucleation of delocalized positive charges, forming conductive paths in the polypyrrole film, was also investigated. The creation of conductive paths during oxidation followed an effective medium rather than a percolative behavior, indicating that some conduction paths survive the polymer reduction steps. The present high surface area material should be well-suited for use in, e.g., electrochemically controlled ion exchange or separation devices, as well as sensors based on the fact that the material is compact, light, mechanically stable, and moldable into paper sheets.

Metallized Nanotube Polymer Composite (MNPC) and Methods for Making Same

NASA Technical Reports Server (NTRS)

Harrison, Joycelyn S. (Inventor); Lowther, Sharon E. (Inventor); Lillehei, Peter T. (Inventor); Park, Cheol (Inventor); Taylor, Larry (Inventor); Kang, Jin Ho (Inventor); Nazem, Negin (Inventor); Kim, Jae-Woo (Inventor); Sauti, Godfrey (Inventor)

2017-01-01

A novel method to develop highly conductive functional materials which can effectively shield various electromagnetic effects (EMEs) and harmful radiations. Metallized nanotube polymer composites (MNPC) are composed of a lightweight polymer matrix, superstrong nanotubes (NT), and functional nanoparticle inclusions. MNPC is prepared by supercritical fluid infusion of various metal precursors (Au, Pt, Fe, and Ni salts), incorporated simultaneously or sequentially, into a solid NT-polymer composite followed by thermal reduction. The infused metal precursor tends to diffuse toward the nanotube surface preferentially as well as the surfaces of the NT-polymer matrix, and is reduced to form nanometer-scale metal particles or metal coatings. The conductivity of the MNPC increases with the metallization, which provides better shielding capabilities against various EMEs and radiations by reflecting and absorbing EM waves more efficiently. Furthermore, the supercritical fluid infusion process aids to improve the toughness of the composite films significantly regardless of the existence of metal.

Dielectric and Energy Storage Properties of the Heterogeneous P(VDF-HFP)/PC Composite Films

NASA Astrophysics Data System (ADS)

Zhao, Xiaojia; Peng, Guirong; Zhan, Zaiji

2017-12-01

Polymer-based materials with a high discharge energy and low energy loss have attracted considerable attention for energy storage applications. A new class of polymer-based composite films composed of amorphous polycarbonate (PC) and poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] has been fabricated by simply solution blending followed by thermal treatment under vacuum. The results show that the diameter of the spherical phase for PC and the melting temperature of P(VDF-HFP) increase, and the crystallinity and crystallization temperature of P(VDF-HFP) decrease with increasing PC content. The phase transition from the polar β phase to weak polarity γ phase is induced by PC addition. Moreover, the Curie temperature of the P(VDF-HFP)/PC composite films shifts to a lower temperature. With the addition of PC, the permittivity, polarization and discharge energy of the P(VDF-HFP)/PC composite films slightly decrease. However, the energy loss is significantly reduced.

Highly conductive composites for fuel cell flow field plates and bipolar plates

DOEpatents

Jang, Bor Z; Zhamu, Aruna; Song, Lulu

2014-10-21

This invention provides a fuel cell flow field plate or bipolar plate having flow channels on faces of the plate, comprising an electrically conductive polymer composite. The composite is composed of (A) at least 50% by weight of a conductive filler, comprising at least 5% by weight reinforcement fibers, expanded graphite platelets, graphitic nano-fibers, and/or carbon nano-tubes; (B) polymer matrix material at 1 to 49.9% by weight; and (C) a polymer binder at 0.1 to 10% by weight; wherein the sum of the conductive filler weight %, polymer matrix weight % and polymer binder weight % equals 100% and the bulk electrical conductivity of the flow field or bipolar plate is at least 100 S/cm. The invention also provides a continuous process for cost-effective mass production of the conductive composite-based flow field or bipolar plate.

Improvement of the Heat Resistance of Prussian Blue Nanoparticles in a Clay Film Composed of Smectite Clay and ε-Caprolactam.

PubMed

Ono, Kenta; Nakamura, Takashi; Ebina, Takeo; Ishizaki, Manabu; Kurihara, Masato

2018-06-04

Prussian blue (PB) is limited in its application by its breakdown at elevated temperatures. To improve the heat resistance of PB, we prepared a composite film comprising PB nanoparticles (NPs), smectite clay, and an organic compound. The composite film had a microstructure in which PB NPs were intercalated between smectite/organic compound layers. The predominant oxidation temperature of the PB NPs in the composite film was around 500 °C in air, higher than the oxidation temperature of bulk PB in air (250 °C). This improvement in the oxidation temperature may be due to the composite film acting as a barrier to oxygen gas. These results indicate the effectiveness of clay materials for the improvement of heat resistance for low-temperature decomposition compounds, not only PB but also other porous coordination polymers.

Lung cell fiber evanescent wave spectroscopic biosensing of inhalation health hazards.

PubMed

Riley, Mark R; Lucas, Pierre; Le Coq, David; Juncker, Christophe; Boesewetter, Dianne E; Collier, Jayne L; DeRosa, Diana M; Katterman, Matthew E; Boussard-Plédel, Catherine; Bureau, Bruno

2006-11-05

Health risks associated with the inhalation of biological materials have been a topic of great concern; however, there are no rapid and automatable methods available to evaluate the potential health impact of inhaled materials. Here we describe a novel approach to evaluate the potential toxic effects of materials evaluated through cell-based spectroscopic analysis. Anchorage-dependent cells are grown on the surface of optical fibers transparent to infrared light. The probe system is composed of a single chalcogenide fiber (composed of Te, As, and Se) acting as both the sensor and transmission line for infrared optical signals. The cells are exposed to potential toxins and alterations of cellular composition are monitored through their impact on cellular spectral features. The signal is collected via evanescent wave absorption along the tapered sensing zone of the fiber through spectral changes between 3,000 and 600 cm(-1) (3,333-16,666 nm). Cell physiology, composition, and function are non-invasively tracked through monitoring infrared light absorption by the cell layer. This approach is demonstrated with an immortalized lung cell culture (A549, human lung carcinoma epithelia) in response to a variety of inhalation hazards including gliotoxin (a fungal metabolite), etoposide (a genotoxin), and methyl methansesulfonate (MMS, an alkylating agent). Gliotoxin impacts cell metabolism, etoposide impacts nucleic acids and the cell cycle, and MMS impacts nucleic acids and induces an immune response. This spectroscopic method is sensitive, non-invasive, and provides information on a wide range of cellular damage and response mechanisms and could prove useful for cell response screening of pharmaceuticals or for toxicological evaluations. (c) 2006 Wiley Periodicals, Inc.

Mechanical intermixing of components in (CoMoNi)-based systems and the formation of (CoMoNi)/WC nanocomposite layers on Ti sheets under ball collisions

NASA Astrophysics Data System (ADS)

Romankov, S.; Park, Y. C.; Shchetinin, I. V.

2017-11-01

Cobalt (Co), molybdenum (Mo), and nickel (Ni) components were simultaneously introduced onto titanium (Ti) surfaces from a composed target using ball collisions. Tungsten carbide (WC) balls were selected for processing as the source of a cemented carbide reinforcement phase. During processing, ball collisions continuously introduced components from the target and the grinding media onto the Ti surface and induced mechanical intermixing of the elements, resulting in formation of a complex nanocomposite structure onto the Ti surface. The as-fabricated microstructure consisted of uniformly dispersed WC particles embedded within an integrated metallic matrix composed of an amorphous phase with nanocrystalline grains. The phase composition of the alloyed layers, atomic reactions, and the matrix grain sizes depended on the combination of components introduced onto the Ti surface during milling. The as-fabricated layer exhibited a very high hardness compared to industrial metallic alloys and tool steel materials. This approach could be used for the manufacture of both cemented carbides and amorphous matrix composite layers.

Beyond the Periodic Table of Elements: The Role of Superatoms.

PubMed

Jena, Puru

2013-05-02

Atomic clusters composed of homo or heteroatomic species constitute an intermediate phase of matter where every atom counts and whose properties depend on their size, shape, composition, and charge. If specific clusters mimicking the chemistry of atoms can be produced, they can be thought of as man-made superatoms forming the building blocks of a new three-dimensional periodic table. Novel materials with tailored properties can then be synthesized by assembling these superatoms. This invited Perspective presents a brief summary of the pioneering works that led to this concept, and highlights the recent breakthroughs that hold promise for a new era in materials science.

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

Palomba, M., E-mail: mariano.palomba@cnr.it; Carotenuto, G.; Binetti, S.

Owing to the very brittle nature of the tellurium powder, nanoscopic grains with average size of 4.8 nm were produced by dry vibration milling technique using a Mixer mill apparatus. A novel material was obtained by binding the nanosized tellurium grains with poly(methyl methacrylate) (PMMA). The morphology, elemental composition, and structural properties of Te/PMMA films were investigated. The prepared material was composed of hexagonal tellurium and α-phase of tellurium oxide. The electrical properties of the films were studied in dark condition and under white light illumination varying the optical power density from 10 to 170 mW/cm{sup 2} and turning onmore » and off the light cyclically.« less

Comparison of mechanical properties for polyamide 12 composite-based biomaterials fabricated by fused filament fabrication and injection molding

NASA Astrophysics Data System (ADS)

Rahim, Tuan Noraihan Azila Tuan; Abdullah, Abdul Manaf; Akil, Hazizan Md; Mohamad, Dasmawati

2016-12-01

The emergence of 3D printing technology known as fused filament fabrication (FFF) has offered the possibility of producing an anatomically accurate, patient specific implant with more affordable prices. The only weakness of this technology is related to incompatibility and lack of properties of current material to be applied in biomedical. Therefore, this study aims to develop a new, polymer composite-based biomaterial that exhibits a high processability using FFF technique, strong enough and shows acceptable biocompatibility, and safe for biomedical use. Polyamide 12 (PA12), which meets all these requirements was incorporated with two bioceramic fillers, zirconia and hydroxyapatite in order to improve the mechanical and bioactivity properties. The obtained mechanical properties were compared with injection-molded specimens and also a commercial biomedical product, HAPEXTM which is composed of hydroxyapatite and polyethylene. The yield strength and modulus of the PA12 composites increased steadily with increasing filler loading. Although the strength of printed PA12 composites were reduced compared with injection molded specimen, but still higher than HAPEXTM material. The higher surface roughness obtained by printed PA12 was expected to enhance the cell adhesion and provide better implant fixation.

Thermite Reaction to Produce Artificial Reefs

NASA Astrophysics Data System (ADS)

Trevino, Alexandro; Martirosyan, Karen; Kline, Richard

The degradation of coral reefs is an ecological issue that has prompted new collaboration by different scientific communities that would assist in the regeneration of the reefs. Unfortunately, these processes can be inefficient and extremely expensive prompting a new scientific approach by using solid-state combustion synthesis to regenerate the reefs. In this report we aimed to consolidate a multi-composite material to produce artificial reefs by initiating thermite reaction based on aluminum and polytetrafluoroethylene (PTFE) with natural reefs. By Thermodynamic analysis and experimentation it was established that a range between .03-.07 number of moles of PTFE was sufficient to reach an adiabatic temperature of over 1900 K, a sustained reaction and a physically stable product was achieved. Reefs are primarily composed of carbonates but their exact chemical composition can vary. X-ray diffraction analysis was used to determine the chemical composition of the reef and revealed presence of oxides, carbonates, silicates. The dominant chemical compounds that were identified are, SiO2 -17%, MgSiO3-14.5%, CaCO3- 11.4%, Ca(Si3O4). Using our thermite reaction we aimed to achieve optimal physical, chemical, and biological properties and maintain cost efficiency of the multi-composite material.

Interaction of Poly(l-lysine)/Polysaccharide Complex Nanoparticles with Human Vascular Endothelial Cells.

PubMed

Weber, Dominik; Torger, Bernhard; Richter, Karsten; Nessling, Michelle; Momburg, Frank; Woltmann, Beatrice; Müller, Martin; Schwartz-Albiez, Reinhard

2018-05-23

Angiogenesis plays an important role in both soft and hard tissue regeneration, which can be modulated by therapeutic drugs. If nanoparticles (NP) are used as vectors for drug delivery, they have to encounter endothelial cells (EC) lining the vascular lumen, if applied intravenously. Herein the interaction of unloaded polyelectrolyte complex nanoparticles (PECNP) composed of cationic poly(l-lysine) (PLL) and various anionic polysaccharides with human vascular endothelial cells (HUVEC) was analyzed. In particular PECNP were tested for their cell adhesive properties, their cellular uptake and intracellular localization considering composition and net charge. PECNP may form a platform for both cell coating and drug delivery. PECNP, composed of PLL in combination with the polysaccharides dextran sulfate (DS), cellulose sulfate (CS) or heparin (HEP), either unlabeled or labeled with fluorescein isothiocyanate (FITC) and either with positive or negative net charge were prepared. PECNP were applied to human umbilical cord vein endothelial cells (HUVEC) in both, the volume phase and immobilized phase at model substrates like tissue culture dishes. The attachment of PECNP to the cell surface, their intracellular uptake, and effects on cell proliferation and growth behavior were determined. Immobilized PECNP reduced attachment of HUVEC, most prominently the systems PLL/HEP and PLL/DS. A small percentage of immobilized PECNP was taken up by cells during adhesion. PECNP in the volume phase showed no effect of the net charge sign and only minor effects of the composition on the binding and uptake of PECNP at HUVEC. PECNP were stored in endosomal vesicles in a cumulative manner without apparent further processing. During mitosis, internalized PECNP were almost equally distributed among the dividing cells. Both, in the volume phase and immobilized at the surface, PECNP composed of PLL/HEP and PLL/DS clearly reduced cell proliferation of HUVEC, however without an apparent cytotoxic effect, while PLL/CS composition showed minor impairment. PECNP have an anti-adhesive effect on HUVEC and are taken up by endothelial cells which may negatively influence the proliferation rate of HUVEC. The negative effects were less obvious with the composition PLL/CS. Since uptake and binding for PLL/HEP was more efficient than for PLL/DS, PECNP of PLL/HEP may be used to deliver growth factors to endothelial cells during vascularization of bone reconstitution material, whereas those of PLL/CS may have an advantage for substituting biomimetic bone scaffold material.

Hydrogen storage properties of nano-structural carbon and metal hydrides composites

NASA Astrophysics Data System (ADS)

Miyaoka, Hiroki; Ichikawa, Takayuki; Isobe, Shigehito; Fujii, Hironobu

2006-08-01

Thermodynamic and structural properties of some ball-milled mixtures composed of the hydrogenated nanostructural carbon (C nanoH x) and metal hydride (MH; M=Li, Na, Mg and Ca) were examined from thermal desoroption mass spectroscopy and powder X-ray diffraction, respectively. The results showed that the hydrogen desorption temperatures are significantly lowered from those of each hydride (C nanoH x, MH) in the composites. This indicates that a new type of interaction exists between C nanoH x and MH, which destabilizes C-H and/or M-H bonding as well. Therefore, the above Metal-C-H system would be recognized as a new family of hydrogen storage materials.

Geophysical characterization of the Lollie Levee near Conway, Arkansas, using capacitively coupled resistivity, coring, and direct push logging

USGS Publications Warehouse

Gillip, Jonathan A.; Payne, Jason

2011-01-01

A geophysical characterization of Lollie Levee near Conway, Arkansas, was conducted in February 2011. A capacitively coupled resistivity survey (using Geometric's OhmMapper) was completed along the top and toe of the 6.7-mile levee. Two-dimensional inversions were conducted on the geophysical data. As a quality-control measure, cores and direct push logs were taken at approximately 1-mile intervals along the levee. The capacitively coupled resistivity survey, the coring, and the direct push logs were used to characterize the geologic materials. Comparison of the cores and the direct push log data, along with published resistivity values, indicates that resistivity values of 200 Ohm-meters or greater represent relatively clean sand, with decreasing resistivity values occurring with increasing silt and clay content. The cores indicated that the levee is composed of a heterogeneous mixture of sand, silt, and clay. The capacitively coupled resistivity sections confirm that the levee is composed of a heterogeneous mixture of high and low resistivity materials and show that the composition of the levee varies spatially. The geologic materials underlying the levee vary spatially as a result of the geologic processes that deposited them. In general, the naturally deposited geologic materials underlying the levee contain a greater amount of low resistivity materials in the southern extent of the levee.

Mechanics of fiber reinforced materials

NASA Astrophysics Data System (ADS)

Sun, Huiyu

This dissertation is dedicated to mechanics of fiber reinforced materials and the woven reinforcement and composed of four parts of research: analytical characterization of the interfaces in laminated composites; micromechanics of braided composites; shear deformation, and Poisson's ratios of woven fabric reinforcements. A new approach to evaluate the mechanical characteristics of interfaces between composite laminae based on a modified laminate theory is proposed. By including an interface as a special lamina termed the "bonding-layer" in the analysis, the mechanical properties of the interfaces are obtained. A numerical illustration is given. For micro-mechanical properties of three-dimensionally braided composite materials, a new method via homogenization theory and incompatible multivariable FEM is developed. Results from the hybrid stress element approach compare more favorably with the experimental data than other existing numerical methods widely used. To evaluate the shearing properties for woven fabrics, a new mechanical model is proposed during the initial slip region. Analytical results show that this model provides better agreement with the experiments for both the initial shear modulus and the slipping angle than the existing models. Finally, another mechanical model for a woven fabric made of extensible yarns is employed to calculate the fabric Poisson's ratios. Theoretical results are compared with the available experimental data. A thorough examination on the influences of various mechanical properties of yarns and structural parameters of fabrics on the Poisson's ratios of a woven fabric is given at the end.

Interrelationship of Nondestructive Evaluation Methodologies Applied to Testing of Composite Overwrapped Pressure Vessels

NASA Technical Reports Server (NTRS)

Leifeste, Mark R.

2007-01-01

Composite Overwrapped Pressure Vessels (COPVs) are commonly used in spacecraft for containment of pressurized gases and fluids, incorporating strength and weight savings. The energy stored is capable of extensive spacecraft damage and personal injury in the event of sudden failure. These apparently simple structures, composed of a metallic media impermeable liner and fiber/resin composite overwrap are really complex structures with numerous material and structural phenomena interacting during pressurized use which requires multiple, interrelated monitoring methodologies to monitor and understand subtle changes critical to safe use. Testing of COPVs at NASA Johnson Space Center White Sands T est Facility (WSTF) has employed multiple in-situ, real-time nondestructive evaluation (NDE) methodologies as well as pre- and post-test comparative techniques to monitor changes in material and structural parameters during advanced pressurized testing. The use of NDE methodologies and their relationship to monitoring changes is discussed based on testing of real-world spacecraft COPVs. Lessons learned are used to present recommendations for use in testing, as well as a discussion of potential applications to vessel health monitoring in future applications.

Superior performance of nanoscaled Fe3O4 as anode material promoted by mosaicking into porous carbon framework

NASA Astrophysics Data System (ADS)

Wan, Wang; Wang, Chao; Zhang, Weidong; Chen, Jitao; Zhou, Henghui; Zhang, Xinxiang

2014-01-01

A nanoscale Fe3O4/porous carbon-multiwalled carbon nanotubes (MWCNTs) composite is synthesized through a simple hard-template method by using Fe2O3 nanoparticles as the precursor and SiO2 nanoparticles as the template. The composite shows good cycle performance (941 mAh g-1 for the first cycle at 0.1 C, with 106% capacity retention at the 80th cycle) and high rate capability (71% capacity retained at 5 C rate). Its excellent electrical properties can be attributed to the porous carbon framework structure, which is composed of carbon and MWCNTs. In this composite, the porous structure provides space for the change in Fe3O4 volume during cycling and shortens the lithium ion diffusion distance, the MWCNTs increase the electron conductivity, and the carbon coating reduces the risk of side reactions. The results provide clear evidences for the utility of porous carbon framework to improve the electrochemical performances of nanosized transition-metal oxides as anode materials for lithium-ion batteries.

Enhanced thermal properties of novel shape-stabilized PEG composite phase change materials with radial mesoporous silica sphere for thermal energy storage.

PubMed

Min, Xin; Fang, Minghao; Huang, Zhaohui; Liu, Yan'gai; Huang, Yaoting; Wen, Ruilong; Qian, Tingting; Wu, Xiaowen

2015-08-11

Radial mesoporous silica (RMS) sphere was tailor-made for further applications in producing shape-stabilized composite phase change materials (ss-CPCMs) through a facile self-assembly process using CTAB as the main template and TEOS as SiO2 precursor. Novel ss-CPCMs composed of polyethylene glycol (PEG) and RMS were prepared through vacuum impregnating method. Various techniques were employed to characterize the structural and thermal properties of the ss-CPCMs. The DSC results indicated that the PEG/RMS ss-CPCM was a promising candidate for building thermal energy storage applications due to its large latent heat, suitable phase change temperature, good thermal reliability, as well as the excellent chemical compatibility and thermal stability. Importantly, the possible formation mechanisms of both RMS sphere and PEG/RMS composite have also been proposed. The results also indicated that the properties of the PEG/RMS ss-CPCMs are influenced by the adsorption limitation of the PEG molecule from RMS sphere with mesoporous structure and the effect of RMS, as the impurities, on the perfect crystallization of PEG.

Enhanced thermal properties of novel shape-stabilized PEG composite phase change materials with radial mesoporous silica sphere for thermal energy storage

PubMed Central

Min, Xin; Fang, Minghao; Huang, Zhaohui; Liu, Yan’gai; Huang, Yaoting; Wen, Ruilong; Qian, Tingting; Wu, Xiaowen

2015-01-01

Radial mesoporous silica (RMS) sphere was tailor-made for further applications in producing shape-stabilized composite phase change materials (ss-CPCMs) through a facile self-assembly process using CTAB as the main template and TEOS as SiO2 precursor. Novel ss-CPCMs composed of polyethylene glycol (PEG) and RMS were prepared through vacuum impregnating method. Various techniques were employed to characterize the structural and thermal properties of the ss-CPCMs. The DSC results indicated that the PEG/RMS ss-CPCM was a promising candidate for building thermal energy storage applications due to its large latent heat, suitable phase change temperature, good thermal reliability, as well as the excellent chemical compatibility and thermal stability. Importantly, the possible formation mechanisms of both RMS sphere and PEG/RMS composite have also been proposed. The results also indicated that the properties of the PEG/RMS ss-CPCMs are influenced by the adsorption limitation of the PEG molecule from RMS sphere with mesoporous structure and the effect of RMS, as the impurities, on the perfect crystallization of PEG. PMID:26261089

Study to investigate design, fabrication and test of low cost concepts for large hybrid composite helicopter fuselage, phase 1

NASA Technical Reports Server (NTRS)

Adams, K. M.; Lucas, J. J.

1975-01-01

The development of a frame/stringer/skin fabrication technique for composite airframe construction was studied as a low cost approach to the manufacture of large helicopter airframe components. A center cabin aluminum airframe section of the Sikorsky CH-53D helicopter was selected for evaluation as a composite structure. The design, as developed, is composed of a woven KEVLAR-49/epoxy skin and graphite/epoxy frames and stringers. To support the selection of this specific design concept a materials study was conducted to develop and select a cure compatible graphite and KEVLAR-49/epoxy resin system, and a foam system capable of maintaining shape and integrity under the processing conditions established. The materials selected were, Narmco 5209/Thornel T-300 graphite, Narmco 5209/KEVLAR-49 woven fabric, and Stathane 8747 polyurethane foam. Eight specimens were fabricated, representative of the frame, stringer, and splice joint attachments. Evaluation of the results of analysis and test indicate that design predictions are good to excellent except for some conservatism of the complex frame splice.

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

Faraby, H.; DiBattista, M.; Bandaru, P. R., E-mail: pbandaru@ucsd.edu

Metal deposition through focused ion beam (FIB) based systems is thought to result in material composed of the primary metal from the metallo-organic precursor in addition to carbon, oxygen, and gallium. We determined, through electrical resistance and chemical composition measurements on a wide range of FIB deposited platinum and tungsten lines, that the gallium ion (Ga{sup +}) concentration in the metal lines plays the dominant role in controlling the electrical resistivity. Effective medium theory, based on McLachlan's formalisms, was used to describe the relationship between the Ga{sup +} concentration and the corresponding resistivity.

Finite lateral compression of an elastic plasticfibre-reinforced tube : loading solutions

NASA Astrophysics Data System (ADS)

England, A. H.; Gregory, P. W.

1999-02-01

This paper considers the finite plane-strain deformations of an elastic-plastic tubecompressed between two rigid smooth parallel plates. The tube is composed of an elastic-plasticfibre-reinforced material in which the fibres lie in planes perpendicular to the axis of the tube andreinforce the tube in the circumferential direction. The composite is assumed to be an idealmaterial which is inextensible in the fibre-direction and is incompressible. The unloading of theelastic-plastic tube will be considered in a subsequent paper.

Method for measuring the density of lightweight materials

DOEpatents

Snow, Samuel G.; Giacomelli, Edward J.

1980-01-01

This invention relates to a nondestructive method for measuring the density of articles composed of elements having a low atomic number such as plastic and carbon composites. The measurement is accomplished by striking the article with a collimated beam of X radiation, simultaneously monitoring the radiation scattered and the radiation transmitted by the article, then relating the ratio of the radiation scattered to the radiation transmitted with the density of the article. The above method is insensitive to all variables except density.

How One Class with One Computer Composed Music

ERIC Educational Resources Information Center

Siegel, Jack

2004-01-01

Music composition is a rewarding activity for students. Through composition, teachers not only address National Standard 4 (composing and arranging music within specified guidelines), but also cover other areas of the music curriculum such as singing, notation, improvisation, form, style, tempo, dynamics, music vocabulary, and assessment. During…

Illusion thermal device based on material with constant anisotropic thermal conductivity for location camouflage

NASA Astrophysics Data System (ADS)

Hou, Quanwen; Zhao, Xiaopeng; Meng, Tong; Liu, Cunliang

2016-09-01

Thermal metamaterials and devices based on transformation thermodynamics often require materials with anisotropic and inhomogeneous thermal conductivities. In this study, still based on the concept of transformation thermodynamics, we designed a planar illusion thermal device, which can delocalize a heat source in the device such that the temperature profile outside the device appears to be produced by a virtual source at another position. This device can be constructed by only one kind of material with constant anisotropic thermal conductivity. The condition which should be satisfied by the device is provided, and the required anisotropic thermal conductivity is then deduced theoretically. This study may be useful for the designs of metamaterials or devices since materials with constant anisotropic parameters have great facility in fabrication. A prototype device has been fabricated based on a composite composed by two naturally occurring materials. The experimental results validate the effectiveness of the device.

Composition and Recorders: A Motivating Experience

ERIC Educational Resources Information Center

Birnie, Rebecca A.

2014-01-01

Composition with students on the elementary level sparks imagination and creativity while engaging students in an experience that can demonstrate personal musical growth. Traditionally, music educators have not been taught how to compose music, let alone lead their students in composing experiences. As music educators take the beginning steps of…

Mediator- and co-catalyst-free direct Z-scheme composites of Bi2WO6-Cu3P for solar-water splitting.

PubMed

Rauf, Ali; Ma, Ming; Kim, Sungsoon; Sher Shah, Md Selim Arif; Chung, Chan-Hwa; Park, Jong Hyeok; Yoo, Pil J

2018-02-08

Exploring new single, active photocatalysts for solar-water splitting is highly desirable to expedite current research on solar-chemical energy conversion. In particular, Z-scheme-based composites (ZBCs) have attracted extensive attention due to their unique charge transfer pathway, broader redox range, and stronger redox power compared to conventional heterostructures. In the present report, we have for the first time explored Cu 3 P, a new, single photocatalyst for solar-water splitting applications. Moreover, a novel ZBC system composed of Bi 2 WO 6 -Cu 3 P was designed employing a simple method of ball-milling complexation. The synthesized materials were examined and further investigated through various microscopic, spectroscopic, and surface area characterization methods, which have confirmed the successful hybridization between Bi 2 WO 6 and Cu 3 P and the formation of a ZBC system that shows the ideal position of energy levels for solar-water splitting. Notably, the ZBC composed of Bi 2 WO 6 -Cu 3 P is a mediator- and co-catalyst-free photocatalyst system. The improved photocatalytic efficiency obtained with this system compared to other ZBC systems assisted by mediators and co-catalysts establishes the critical importance of interfacial solid-solid contact and the well-balanced position of energy levels for solar-water splitting. The promising solar-water splitting under optimum composition conditions highlighted the relationship between effective charge separation and composition.

Assessment of exposures and potential risks to the US adult population from the leaching of elements from gold and ceramic dental restorations.

PubMed

Richardson, G Mark; James, Kyle Jordan; Peters, Rachel Elizabeth; Clemow, Scott Richard; Siciliano, Steven Douglas

2016-01-01

Using data from the 2001 to 2004 US National Health and Nutrition Examination Survey (NHANES) on the number and placement of tooth restorations in adults, we quantified daily doses due to leaching of elements from gold (Au) alloy and ceramic restorative materials. The elements with the greatest leaching rates from these materials are often the elements of lowest proportional composition. As a result, exposure due to wear will predominate for those elements of relatively high proportional composition, while exposure due leaching may predominate for elements of relatively low proportional composition. The exposure due to leaching of silver (Ag) and palladium (Pd) from Au alloys exceeded published reference exposure levels (RELs) for these elements when multiple full surface crowns were present. Six or more molar crowns would result in exceeding the REL for Ag, whereas three or more crowns would be necessary to exceed the REL for Pd. For platinum (Pt), the majority of tooth surfaces, beyond just molar crowns, would be necessary to exceed the REL for Pd. Exposures due to leaching of elements from ceramic dental materials were less than published RELs for all components examined here, including having all restorations composed of ceramic.

Characterization of Morphology and Composition of Inorganic Fillers in Dental Alginates

PubMed Central

Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

2014-01-01

Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450°C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C—81.59%, H—79.89%, O—78.87%, H5—77.95%, JP—66.88%, wt). The filler fractions in volume (vt) were as follows: H5—84.85%, JP—74.76%, H—70.03%, O—68.31%, and C—56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology. PMID:25165690

Template-assisted formation of microsized nanocrystalline CeO2 tubes and their catalytic performance in the carboxylation of methanol

PubMed Central

Naumann, Meike; Schäfer, Christian; Brandner, Armin; Hofmann, Heiko J; Claus, Peter

2011-01-01

Summary Polymethylmethacrylate (PMMA)/ceria composite fibres were synthesized by using a sequential combination of polymer electrospinning, spray-coating with a sol, and a final calcination step to yield microstructured ceria tubes, which are composed of nanocrystalline ceria particles. The PMMA template is removed from the organic/inorganic hybrid material by radio frequency (rf) plasma etching followed by calcination of the ceramic green-body fibres. Microsized ceria (CeO2) tubes, with a diameter of ca. 0.75 µm, composed of nanocrystalline agglomerated ceria particles were thus obtained. The 1-D ceramic ceria material was characterized by X-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV–vis and photoluminescence spectroscopy (PL), as well as thermogravimetric analysis (TGA). Its catalytic performance was studied in the direct carboxylation of methanol with carbon dioxide leading to dimethyl carbonate [(CH3O)2CO, DMC], which is widely employed as a phosgene and dimethyl sulfate substitute, and as well as a fuel additive. PMID:22259761

Determination Of Constituent Concentration In Fluid Mixtures Using Magnetic Resonance Imaging

NASA Astrophysics Data System (ADS)

Galloway, Robert L.; Collins, Jerry C.; Carroll, Frank E.

1987-01-01

The primary application of magnetic resonance imaging (MRI) has been qualitative and anatomical evaluation of patient status. Recent efforts to analyze image information for quantitative evaluation centered on two relaxation parameters, Tl and T2, as the descriptors for the image data. In our work we have found that relaxation curves for biologic materials cannot be described by a monoexponential function and that, in a spin echo system, calculated Tl values are dependent on repetition time. This finding is not unexpected since, in physiologic imaging, any region of interest (ROI), is composed of a number of distinct substances and the response of that ROI will be a composite of the constituent materials. The purpose of our study was to develop a method by which the relaxation behaviors of a composite of physiological material might be characterized and use that characterization to determine its constituent materials. We created a phantom in which volumes of several "pure" materials (blood, plasma, saline and oil) were available as well as volumes which contained concentric enclosures of the pure materials. Images were formed at a number of repetition times, ranging from 160 milliseconds to 2 seconds. The image data was then transferred to a VAX 11/750 where regions of interest were marked and the mean image intensity for each ROI at each repetition time was calculated. The resultant relaxation curves of the pure materials formed basis vectors for the composite responses and the fractional content of each material was determined by a least-square error fit to the basis vectors. Excellent agreement was seen between known and measured mixture percentages. Ongoing work is centered around optimizing repetition time selection and accounting for the interaction between species in the mixtures.

An Analysis of the Macroscopic Tensile Behavior of a Nonlinear Nylon Reinforced Elastomeric Composite System Using MAC/GMC

NASA Technical Reports Server (NTRS)

Assaad, Mahmoud; Arnold, Steven M.

1999-01-01

A special class of composite laminates composed of soft rubbery matrices and stiff reinforcements made of steel wires or synthetic fibers is examined, where each constituent behaves in a nonlinear fashion even in the small strain domain. Composite laminates made of piles stacked at alternating small orientation angles with respect to the applied axial strain are primarily dominated by the nonlinear behavior of the reinforcing fibers. However; composites with large ply orientations or those perpendicular to the loading axis, will approximate the behavior of the matrix phase and respond in even a more complex fashion for arbitrarily stacked piles. The geometric nonlinearity due to small cord rotations during loading was deemed here to have a second order effect and consequently dropped from any consideration. The user subroutine USRMAT within the Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC), was utilized to introduce the constituent material nonlinear behavior. Stress-strain behavior at the macro level was experimentally generated for single and multi ply composites comprised of continuous Nylon-66 reinforcements embedded in a carbon black loaded rubbery matrix. Comparisons between the predicted macro composite behavior and experimental results are excellent when material nonlinearity is included in the analysis. In this paper, a brief review of GMC is provided, along with a description of the nonlinear behavior of the constituents and associated constituent constitutive relations, and the improved macro (or composite) behavior predictions are documented and illustrated.

Mechanics of Platelet-Matrix Composites across Scales: Theory, Multiscale Modeling, and 3D Fabrication

NASA Astrophysics Data System (ADS)

Sakhavand, Navid

Many natural and biomimetic composites - such as nacre, silk and clay-polymer - exhibit a remarkable balance of strength, toughness, and/or stiffness, which call for a universal measure to quantify this outstanding feature given the platelet-matrix structure and material characteristics of the constituents. Analogously, there is an urgent need to quantify the mechanics of emerging electronic and photonic systems such as stacked heterostructures, which are composed of strong in-plane bonding networks but weak interplanar bonding matrices. In this regard, development of a universal composition-structure-property map for natural platelet-matrix composites, and stacked heterostructures opens up new doors for designing materials with superior mechanical performance. In this dissertation, a multiscale bottom-up approach is adopted to analyze and predict the mechanical properties of platelet-matrix composites. Design guidelines are provided by developing universally valid (across different length scales) diagrams for science-based engineering of numerous natural and synthetic platelet-matrix composites and stacked heterostructures while significantly broadening the spectrum of strategies for fabricating new composites with specific and optimized mechanical properties. First, molecular dynamics simulations are utilized to unravel the fundamental underlying physics and chemistry of the binding nature at the atomic-level interface of organic-inorganic composites. Polymer-cementitious composites are considered as case studies to understand bonding mechanism at the nanoscale and open up new venues for potential mechanical enhancement at the macro-scale. Next, sophisticated mathematical derivations based on elasticity and plasticity theories are presented to describe pre-crack (intrinsic) mechanical performance of platelet-matrix composites at the microscale. These derivations lead to developing a unified framework to construct series of universal composition-structure-property maps that decode the interplay between various geometries and inherent material features, encapsulated in a few dimensionless parameters. Finally, after crack mechanical properties (extrinsic) of platelet-matrix composites until ultimate failure of the material at the macroscale is investigated via combinatorial finite element simulations. The effect of different composition-structure-property parameters on mechanical properties synergies are depicted via 2D and 3D maps. 3D-printed specimens are fabricated and tested against the theoretical prediction. The combination of the presented diagrams and guidelines paves the path toward platelet-matrix composites and stacked-heterostructures with superior and optimized mechanical properties.

Novel Robotic Platforms for the Accurate Sampling and Monitoring of Water Columns

PubMed Central

Fernández, Roemi; Apalkov, Andrey; Armada, Manuel

2016-01-01

The hydrosphere contains large amounts of suspended particulate material, including living and non-living material that can be found in different compositions and concentrations, and that can be composed of particles of different sizes. The study of this particulate material along water columns plays a key role in understanding a great variety of biological, chemical, and physical processes. This paper presents the conceptual design of two patented robotic platforms that have been conceived for carrying out studies of water properties at desired depths with very high accuracy in the vertical positioning. One platform has been specially designed for operating near to a reservoir bottom, while the other is intended to be used near the surface. Several experimental tests have been conducted in order to validate the proposed approaches. PMID:27589745

Green piezoelectric for autonomous smart textile

NASA Astrophysics Data System (ADS)

Lemaire, E.; Borsa, C. J.; Briand, D.

2015-12-01

In this work, the fabrication of Rochelle salt based piezoelectric textiles are shown. Structures composed of fibers and Rochelle salt are easily produced using green processes. Both manufacturing and the material itself are really efficient in terms of environmental impact, considering the fabrication processes and the material resources involved. Additionally Rochelle salt is biocompatible. In this green paradigm, active sensing or actuating textiles are developed. Thus processing method and piezoelectric properties have been studied: (1) pure crystals are used as acoustic actuator, (2) fabrication of the textile-based composite is detailed, (3) converse effective d33 is evaluated and compared to lead zirconate titanate ceramic. The utility of textile-based piezoelectric merits its use in a wide array of applications.

Muscle Motion Solenoid Actuator

NASA Astrophysics Data System (ADS)

Obata, Shuji

It is one of our dreams to mechanically recover the lost body for damaged humans. Realistic humanoid robots composed of such machines require muscle motion actuators controlled by all pulling actions. Particularly, antagonistic pairs of bi-articular muscles are very important in animal's motions. A system of actuators is proposed using the electromagnetic force of the solenoids with the abilities of the stroke length over 10 cm and the strength about 20 N, which are needed to move the real human arm. The devised actuators are based on developments of recent modern electro-magnetic materials, where old time materials can not give such possibility. Composite actuators are controlled by a high ability computer and software making genuine motions.

New materials through a variety of sintering methods

NASA Astrophysics Data System (ADS)

Jaworska, L.; Cyboroń, J.; Cygan, S.; Laszkiewicz-Łukasik, J.; Podsiadło, M.; Novak, P.; Holovenko, Y.

2018-03-01

New sintering techniques make it possible to obtain materials with special properties that are impossible to obtain by conventional sintering techniques. This issue is especially important for ceramic materials for application under extreme conditions. Following the tendency to limit critical materials in manufacturing processes, the use of W, Si, B, Co, Cr should be limited, also. One of the cheapest and widely available materials is aluminum oxide, which shows differences in phase composition, grain size, hardness, strain and fracture toughness of the same type of powder, sintered via various methods. In this paper the alumina was sintered using the conventional free sintering process, microwave sintering, Spark Plasma Sintering (SPS), high pressure-high temperature method (HP-HT) and High Pressure Spark Plasma Sintering (HP SPS). Phase composition analysis, by X-ray diffraction of the alumina materials sintered using various methods, was carried out. For the conventional sintering method, compacts are composed of α-Al2O3 and θ-Al2O3. For compacts sintered using SPS, microwave and HP-HT methods, χ-Al2O3 and γ-Al2O3 phases were additionally present. Mechanical and physical properties of the obtained materials were compared between the methods of sintering. On the basis of images from scanning electron microscope quantitative analysis was performed to determine the degree of grain growth of alumina after sintering.

Embedded Aligned Carbon Nanotube Sheets for Strain and Damage sensing in Composite Structures

NASA Astrophysics Data System (ADS)

Aly, Karim Aly Abdelomoaty Elsayed

The world demand for fiber reinforced composite materials has been steadily increasing because of the widespread adoption of this class of material in many markets. The automotive, aerospace, marine and energy sectors account for a large percentage of this grow. Outstanding fatigue performance, high specific stiffness and strength, and low density are among the most important properties that fiber reinforced polymer composites offer. Furthermore, their properties can be tailored to meet the specific needs of the final applications. However, this class of material is composed of multiple layers of inhomogeneous and anisotropic constituents, i.e. fibers and matrix. Therefore, this laminated nature make the composite material prone to intrinsic damage including interfacial debonding and delamination and their strength and failure are dependent on the fiber architecture and direction of the applied stresses. Consequently, it is of prime importance to monitor the health of these structures. New and improved methods for early detection of damage and structural health monitoring of composite materials may allow for enhanced reliability, lifetime and performance while minimizing maintenance time during a composite part's service life. Over the last few decades different non-destructive methods and materials have been investigated for use as strain sensors. Since the discovery of carbon nanotubes (CNTs), they have attracted much research interest due to their superior electrical, thermal and mechanical properties as well as their high aspect ratio. In this context, CNTs have been used in the recent years to enable sensing capabilities. In this dissertation, the usage of CNTs for performing strain and damage sensing in composites is evaluated. This was enabled by embedding aligned sheets of two millimeters long, interconnected CNTs into laminated structures that were then subjected to different forms of mechanical loading. The localization of the CNT sheets inside the host structure was done using a novel technique that allowed for carrying out the embedment task conveniently and repeatedly. The real-time electrical resistance change of the CNT sheets in response to the applied mechanical stresses was measured in-situ so that the electromechnical behavior of the CNTs could be linked to the strain change and damage in the host structure. The quasi-static and dynamic flexural, axial tensile and compression loadings of the composite structures revealed that the CNT sheets exhibited sensitivity, stability and repeatability which are vital properties for any successful health monitoring technique. (Abstract shortened by ProQuest.).

A novel anoxic-aerobic biofilter process using new composite packing material for the treatment of rural domestic wastewater.

PubMed

Pan, L T; Han, Y

2016-01-01

A pilot scale experiment was conducted to evaluate the characteristics of contaminants removal in a continuously two-stage biological process composed of an anoxic biofilter (AF) and an biological aerated filter (BAF). This novel process was developed by introducing new composite packing material (MZF) into bioreactors to treat rural domestic wastewater. A comparative study conducted by the same process with ceramsite as packing material under the same conditions showed that a MZF system with a Fe proportion in the packing material performed better in chemical oxygen demand (COD) removal (average 91.5%), ammonia (NH4(+)-N) removal (average 98.3%), total nitrogen (TN) removal (average 64.8%) and total phosphorus (TP) removal (average 90%). After treatment of the MZF system, the concentrations of COD, NH4(+)-N, TN and TP in effluent were 20.3 mg/L, 0.5 mg/L, 11.5 mg/L and 0.3 mg/L, respectively. The simultaneously high efficiencies of nitrification, denitrification and phosphorus removal were achieved by the coupling effects of biological and chemical processes in the MZF system. The results of this study showed that the application of MZF might be a favorable choice as packing material in biofilters for treatment of rural domestic wastewater.

Engineered soy oils for new value added applications

NASA Astrophysics Data System (ADS)

Tran, Phuong T.

Soybean oil is an abundant annually renewable resource. It is composed of triglycerides with long chain saturated and unsaturated fatty acids. The presence of unsaturated fatty acids allows for chemical modification to introduce new functionalities to soybean oil. A portfolio of chemically modified soy oil with suitable functional groups has been designed and engineered to serve as the starting material in applications such as polyamides, polyesters, polyurethanes, composites, and lubricants. Anhydride, hydroxyl, and silicone functionalities were introduced to soy oil. Anhydride functionality was introduced using a single-step free radical initiated process, and the chemically modified soy oils were evaluated for potential applications as a composite and lubricant. Hydroxyl functionalities were introduced in a single-step catalytic ozonolysis process recently developed in our labs, which proceeds rapidly and efficiently at room temperature without solvent. The transformed soy oil was used to successfully prepare bio-lubricants with good thermal/oxidative stability and bio-plastics such as polyamides, polyesters, and polyurethanes. A new class of organic-inorganic hybrid materials was prepared by curing vinyltrimethoxysilane functionalized soy oil. This hybrid material could have potential as biobased sealant through a moisture initiated room temperature cure. These new classes of soy-based materials are competitive both in cost and performance to petroleum based materials, but offer the advantage of being biobased.

Sequoias, Mavericks, Open Doors...Composing Joan Tower

ERIC Educational Resources Information Center

Allsup, Randall Everett

2011-01-01

This essay interview with Joan Tower is a meditation on the importance of composing, understood as a process larger than the making of new sound combinations or musical scores, suggesting that the compositional act is self-educative and self-forming. Tower's musical life, one of teaching and learning, one of composing and self-composing, is an…

Fabrication and thermophysical property characterization of UN/U 3Si 2 composite fuel forms

DOE PAGES

White, Joshua Taylor; Travis, Austin William; Dunwoody, John Tyler; ...

2017-09-21

High uranium density composite fuels composed of UN and U 3Si 2 have been fabricated using a liquid phase sintering route at temperatures between 1873 K and 1973 K and spanning compositions of 10 vol% to 40 vol% U 3Si 2. Microstructural analysis and phase characterization revealed the formation of an U-Si-N phase of unknown structure. Microcracking was observed in the U-Si portion of the composite microstructure that likely originates from the mismatched coefficient of thermal expansion between the UN and U 3Si 2 leading to stresses on heating and cooling of the composite. Thermal expansion coefficient, thermal diffusivity, andmore » thermal conductivity were characterized for each of the compositions as a function of temperature to 1673 K. Hysteresis is observed in the thermal diffusivity for the 20 vol% through 40 vol% specimens between room temperature and 1273 K, which is attributed to the microcracking in the U-Si phase. Thermal conductivity of the composites was modeled using the MOOSE framework based on the collected microstructure data. In conclusion, the impact of irradiation on thermal conductivity was also simulated for this class of composite materials.« less

Fabrication and thermophysical property characterization of UN/U 3Si 2 composite fuel forms

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

White, Joshua Taylor; Travis, Austin William; Dunwoody, John Tyler

High uranium density composite fuels composed of UN and U 3Si 2 have been fabricated using a liquid phase sintering route at temperatures between 1873 K and 1973 K and spanning compositions of 10 vol% to 40 vol% U 3Si 2. Microstructural analysis and phase characterization revealed the formation of an U-Si-N phase of unknown structure. Microcracking was observed in the U-Si portion of the composite microstructure that likely originates from the mismatched coefficient of thermal expansion between the UN and U 3Si 2 leading to stresses on heating and cooling of the composite. Thermal expansion coefficient, thermal diffusivity, andmore » thermal conductivity were characterized for each of the compositions as a function of temperature to 1673 K. Hysteresis is observed in the thermal diffusivity for the 20 vol% through 40 vol% specimens between room temperature and 1273 K, which is attributed to the microcracking in the U-Si phase. Thermal conductivity of the composites was modeled using the MOOSE framework based on the collected microstructure data. In conclusion, the impact of irradiation on thermal conductivity was also simulated for this class of composite materials.« less

The neuronal porosome complex in health and disease

PubMed Central

Naik, Akshata R; Lewis, Kenneth T

2015-01-01

Cup-shaped secretory portals at the cell plasma membrane called porosomes mediate the precision release of intravesicular material from cells. Membrane-bound secretory vesicles transiently dock and fuse at the base of porosomes facing the cytosol to expel pressurized intravesicular contents from the cell during secretion. The structure, isolation, composition, and functional reconstitution of the neuronal porosome complex have greatly progressed, providing a molecular understanding of its function in health and disease. Neuronal porosomes are 15 nm cup-shaped lipoprotein structures composed of nearly 40 proteins, compared to the 120 nm nuclear pore complex composed of >500 protein molecules. Membrane proteins compose the porosome complex, making it practically impossible to solve its atomic structure. However, atomic force microscopy and small-angle X-ray solution scattering studies have provided three-dimensional structural details of the native neuronal porosome at sub-nanometer resolution, providing insights into the molecular mechanism of its function. The participation of several porosome proteins previously implicated in neurotransmission and neurological disorders, further attest to the crosstalk between porosome proteins and their coordinated involvement in release of neurotransmitter at the synapse. PMID:26264442

Facile preparation of well-combined lignin-based carbon/ZnO hybrid composite with excellent photocatalytic activity

NASA Astrophysics Data System (ADS)

Wang, Huan; Qiu, Xueqing; Liu, Weifeng; Yang, Dongjie

2017-12-01

In this work, a novel lignin-based carbon/ZnO (LC/ZnO) hybrid composite with excellent photocatalytic performance was prepared through a convenient and environment friendly method using alkali lignin (AL) as carbon source. The morphological, microstructure and optical properties of the as-prepared LC/ZnO hybrid composite was characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), Raman and UV-vis. The resulting LC/ZnO hybrid is composed of highly dispersed ZnO nanoparticles embedded on a lignin-based carbon nanosheet, showing excellent photogenerated electrons and holes separation and migration efficiency. The photocatalytic activity of LC/ZnO was much higher than the pure ZnO. The LC/ZnO hybrid composite showed different photocatalytic mechanism for degradation of negative methyl orange (MO) and positive Rhodamine B (RhB). It showed that h+ was the main photocatalytic active group during the degradation of MO, ·O2- and ·OH were the photocatalytic active groups during degradation of RhB. This reported photocatalyst with selective degradation of positive and negative organic dyes may have a great application prospect for photoelectric conversion and catalytic materials. Results of this work were of practical importance for high-valued utilization of lignin for carbon materials.

Preparation, Mechanical and Thermal Properties of Cement Board with Expanded Perlite Based Composite Phase Change Material for Improving Buildings Thermal Behavior

PubMed Central

Ye, Rongda; Fang, Xiaoming; Zhang, Zhengguo; Gao, Xuenong

2015-01-01

Here we demonstrate the mechanical properties, thermal conductivity, and thermal energy storage performance of construction elements made of cement and form-stable PCM-Rubitherm® RT 28 HC (RT28)/expanded perlite (EP) composite phase change materials (PCMs). The composite PCMs were prepared by adsorbing RT28 into the pores of EP, in which the mass fraction of RT28 should be limited to be no more than 40 wt %. The adsorbed RT28 is observed to be uniformly confined into the pores of EP. The phase change temperatures of the RT28/EP composite PCMs are very close to that of the pure RT28. The apparent density and compression strength of the composite cubes increase linearly with the mass fraction of RT28. Compared with the thermal conductivity of the boards composed of cement and EP, the thermal conductivities of the composite boards containing RT28 increase by 15%–35% with the mass fraction increasing of RT28. The cubic test rooms that consist of six boards were built to evaluate the thermal energy storage performance, it is found that the maximum temperature different between the outside surface of the top board with the indoor temperature using the composite boards is 13.3 °C higher than that of the boards containing no RT28. The thermal mass increase of the built environment due to the application of composite boards can contribute to improving the indoor thermal comfort and reducing the energy consumption in the buildings. PMID:28793671

Preparation, Mechanical and Thermal Properties of Cement Board with Expanded Perlite Based Composite Phase Change Material for Improving Buildings Thermal Behavior.

PubMed

Ye, Rongda; Fang, Xiaoming; Zhang, Zhengguo; Gao, Xuenong

2015-11-13

Here we demonstrate the mechanical properties, thermal conductivity, and thermal energy storage performance of construction elements made of cement and form-stable PCM-Rubitherm® RT 28 HC (RT28)/expanded perlite (EP) composite phase change materials (PCMs). The composite PCMs were prepared by adsorbing RT28 into the pores of EP, in which the mass fraction of RT28 should be limited to be no more than 40 wt %. The adsorbed RT28 is observed to be uniformly confined into the pores of EP. The phase change temperatures of the RT28/EP composite PCMs are very close to that of the pure RT28. The apparent density and compression strength of the composite cubes increase linearly with the mass fraction of RT28. Compared with the thermal conductivity of the boards composed of cement and EP, the thermal conductivities of the composite boards containing RT28 increase by 15%-35% with the mass fraction increasing of RT28. The cubic test rooms that consist of six boards were built to evaluate the thermal energy storage performance, it is found that the maximum temperature different between the outside surface of the top board with the indoor temperature using the composite boards is 13.3 °C higher than that of the boards containing no RT28. The thermal mass increase of the built environment due to the application of composite boards can contribute to improving the indoor thermal comfort and reducing the energy consumption in the buildings.

Effect of Fe(II)/Ce(III) dosage ratio on the structure and anion adsorptive removal of hydrothermally precipitated composites: Insights from EXAFS/XANES, XRD and FTIR.

PubMed

Chubar, Natalia; Gerda, Vasyl; Banerjee, Dipanjan; Yablokova, Ganna

2017-02-01

In this work, we present material chemistry in the hydrothermal synthesis of new complex structure materials based on various dosage ratios of Fe and Ce (1:0, 2:1, 1:1, 1:2, 0:1), characterize them by the relevant methods that allow characterization of both crystalline and amorphous phases and correlate their structure/surface properties with the adsorptive performance of the five toxic anions. The applied synthesis conditions resulted in the formation of different compounds of Fe and Ce components. The Fe-component was dominated by various phases of Fe hydrous oxides, whereas the Ce-component was composed of various phases of Ce carbonates. The presence of two metal salts in raw materials resulted in the formation of a mesoporous structure and averaged the surface area compared to one metal-based material. The surface of all Fe-Ce composites was abundant in Fe component phases. Two-metal systems showed stronger anion removal performance than one-metal materials. The best adsorption was demonstrated by Fe-Ce based materials that had low crystallinity, that were rich in phases and that exhibited surfaces were abundant in greater number of surface functional groups. Notably, Fe extended fine structures simulated by EXAFS in these better adsorbents were rich from oscillations from both heavy and light atoms. This work provides new insights on the structure of composite inorganic materials useful to develop their applications in adsorption and catalysis. It also presents new inorganic anion exchangers with very high removal potential to fluoride and arsenate. Copyright © 2016 Elsevier Inc. All rights reserved.

Compositional disorder and its effect on the thermoelectric performance of Zn₃P₂ nanowire-copper nanoparticle composites.

PubMed

Brockway, Lance; Vasiraju, Venkata; Vaddiraju, Sreeram

2014-03-28

Recent studies indicated that nanowire format of materials is ideal for enhancing the thermoelectric performance of materials. Most of these studies were performed using individual nanowires as the test elements. It is not currently clear whether bulk assemblies of nanowires replicate this enhanced thermoelectric performance of individual nanowires. Therefore, it is imperative to understand whether enhanced thermoelectric performance exhibited by individual nanowires can be extended to bulk assemblies of nanowires. It is also imperative to know whether the addition of metal nanoparticle to semiconductor nanowires can be employed for enhancing their thermoelectric performance further. Specifically, it is important to understand the effect of microstructure and composition on the thermoelectric performance on bulk compound semiconductor nanowire-metal nanoparticle composites. In this study, bulk composites composed of mixtures of copper nanoparticles with either unfunctionalized or 1,4-benzenedithiol (BDT) functionalized Zn₃P₂ nanowires were fabricated and analyzed for their thermoelectric performance. The results indicated that use of BDT functionalized nanowires for the fabrication of composites leads to interface-engineered composites that have uniform composition all across their cross-section. The interface engineering allows for increasing their Seebeck coefficients and electrical conductivities, relative to the Zn₃P₂ nanowire pellets. In contrast, the use of unfunctionalized Zn₃P₂ nanowires for the fabrication of composite leads to the formation of composites that are non-uniform in composition across their cross-section. Ultimately, the composites were found to have Zn₃P₂ nanowires interspersed with metal alloy nanoparticles. Such non-uniform composites exhibited very high electrical conductivities, but slightly lower Seebeck coefficients, relative to Zn₃P₂ nanowire pellets. These composites were found to show a very high zT of 0.23 at 770 K, orders of magnitude higher than either interface-engineered composites or Zn₃P₂ nanowire pellets. The results indicate that microstructural composition of semiconductor nanowire-metal nanoparticle composites plays a major role in determining their thermoelectric performance, and such composites exhibit enhanced thermoelectric performance.

Petrology and thermal history of type IA chondrules in the Semarkona (LL3.0) chondrite

NASA Technical Reports Server (NTRS)

Jones, R. H.; Scott, E. R. D.

1989-01-01

Detailed petrologic studies have been made of 15 type IA, Fe-poor, porphyritic olivine chondrules in Semarkona (LL3.0). Major and minor element concentrations in olivines, pyroxenes, and mesostases, and bulk composition so the chondrules are measured along with zoning profiles in the olivine and pyroxene crystals. The mineral compositions and textures are best interpreted in terms of closed system crystallization in which the olivines and pyroxenes crystallized in situ from a melt corresponding to the bulk composition of the chondrule. Relict olivine grains are not found in the chondrules. Crystallization probably occurred at a cooling rate of the order of 1000 C/hr. Precursor materials of the chondrules were composed of two components, one refractory Ca-, Al-, and Ti-rich, and one less refractory Si-, Fe-, Cr-, and Mn-rich. The evidence is consistent with Semarkona being one of the least metamorphosed ordinary chondrites.

Vibration-immune high-sensitivity profilometer built with the technique of composite interferometry.

PubMed

Lin, Yu-Kai; Chang, Chun-Wei; Hou, Max T; Hsu, I-Jen

2016-03-10

A prototype of a profilometer was built with the technique of composite interferometry for measurement of the distribution of both the amplitude and phase information of the surface of a material simultaneously. The composite interferometer was composed of a Michelson interferometer for measuring the surface profile of the sample and a Mach-Zehnder interferometer for measuring the phase deviation caused by the scanning component and environmental perturbations. A high-sensitivity surface profile can be obtained by use of the phase compensation mechanism through subtraction of the phases of the interferograms detected in the two interferometers. With the new design and improvement of robustness of the optical system, the measurement speed and accuracy were significantly improved. Furthermore, an additional optical delay component results in a higher sensitivity of the interference signal. This prototype of vibration-immune profilometer was examined to have a displacement sensitivity of 0.64 nm.

Deployment of Large-Size Shell Constructions by Internal Pressure

NASA Astrophysics Data System (ADS)

Pestrenin, V. M.; Pestrenina, I. V.; Rusakov, S. V.; Kondyurin, A. V.

2015-11-01

A numerical study on the deployment pressure (the minimum internal pressure bringing a construction from the packed state to the operational one) of large laminated CFRP shell structures is performed using the ANSYS engineering package. The shell resists both membrane and bending deformations. Structures composed of shell elements whose median surface has an involute are considered. In the packed (natural) states of constituent elements, the median surfaces coincide with their involutes. Criteria for the termination of stepwise solution of the geometrically nonlinear problem on determination of the deployment pressure are formulated, and the deployment of cylindrical, conical (full and truncated cones), and large-size composite shells is studied. The results obtained are shown by graphs illustrating the deployment pressure in relation to the geometric and material parameters of the structure. These studies show that large pneumatic composite shells can be used as space and building structures, because the deployment pressure in them only slightly differs from the excess pressure in pneumatic articles made from films and soft materials.

Heterogeneous ligand-nanoparticle distributions: a major obstacle to scientific understanding and commercial translation.

PubMed

Mullen, Douglas G; Banaszak Holl, Mark M

2011-11-15

Nanoparticles conjugated with functional ligands are expected to have a major impact in medicine, photonics, sensing, and nanoarchitecture design. One major obstacle to realizing the promise of these materials, however, is the difficulty in controlling the ligand/nanoparticle ratio. This obstacle can be segmented into three key areas: First, many designs of these systems have failed to account for the true heterogeneity of ligand/nanoparticle ratios that compose each material. Second, studies in the field often use the mean ligand/nanoparticle ratio as the accepted level of characterization of these materials. This measure is insufficient because it does not provide information about the distribution of ligand/nanoparticle species within a sample or the number and relative amount of the different species that compose a material. Without these data, researchers do not have an accurate definition of material composition necessary both to understand the material-property relationships and to monitor the consistency of the material. Third, some synthetic approaches now in use may not produce consistent materials because of their sensitivity to reaction kinetics and to the synthetic history of the nanoparticle. In this Account, we describe recent advances that we have made in under standing the material composition of ligand-nanoparticle systems. Our work has been enabled by a model system using poly(amidoamine) dendrimers and two small molecule ligands. Using reverse phase high-pressure liquid chromatography (HPLC), we have successfully resolved and quantified the relative amounts and ratios of each ligand/dendrimer combination. This type of information is rare within the field of ligand-nanoparticle materials because most analytical techniques have been unable to identify the components in the distribution. Our experimental data indicate that the actual distribution of ligand-nanoparticle components is much more heterogeneous than is commonly assumed. The mean ligand/nanoparticle ratio that is typically the only information known about a material is insufficient because the mean does not provide information on the diversity of components in the material and often does not describe the most common component (the mode). Additionally, our experimental data has provided examples of material batches with the same mean ligand/nanoparticle ratio and very different distributions. This discrepancy indicates that the mean cannot be used as the sole metric to assess the reproducibility of a system. We further found that distribution profiles can be highly sensitive to the synthetic history of the starting material as well as slight changes in reaction conditions. We have incorporated the lessons from our experimental data into the design of new ligand-nanoparticle systems to provide improved control over these ratios.

Homogenization-based interval analysis for structural-acoustic problem involving periodical composites and multi-scale uncertain-but-bounded parameters.

PubMed

Chen, Ning; Yu, Dejie; Xia, Baizhan; Liu, Jian; Ma, Zhengdong

2017-04-01

This paper presents a homogenization-based interval analysis method for the prediction of coupled structural-acoustic systems involving periodical composites and multi-scale uncertain-but-bounded parameters. In the structural-acoustic system, the macro plate structure is assumed to be composed of a periodically uniform microstructure. The equivalent macro material properties of the microstructure are computed using the homogenization method. By integrating the first-order Taylor expansion interval analysis method with the homogenization-based finite element method, a homogenization-based interval finite element method (HIFEM) is developed to solve a periodical composite structural-acoustic system with multi-scale uncertain-but-bounded parameters. The corresponding formulations of the HIFEM are deduced. A subinterval technique is also introduced into the HIFEM for higher accuracy. Numerical examples of a hexahedral box and an automobile passenger compartment are given to demonstrate the efficiency of the presented method for a periodical composite structural-acoustic system with multi-scale uncertain-but-bounded parameters.

Metamorphozed Hercynian granitoids in the Alpine structures of the Central Rhodope, Bulgaria: geotectonic position and geochemistry

NASA Astrophysics Data System (ADS)

Cherneva, Zlatka; Georgieva, Milena

2005-05-01

Orthogneisses of late-Hercynian protolith age crop out in the Central Rhodope high-grade metamorphic complex, which is part of the Alpine orogen in south-eastern Europe. They compose a tectonic unit bordered by late-Alpine extensional shear zones. These rocks reflect Eocene amphibolite facies migmatization (<750 °C/0.9-0.5 GPa). The low-temperature melting favored zircon inheritance and disturbed mainly the LILE protolith compositions. Despite the intense Alpine metamorphic overprint, the major elements, HFSE and REE reflect the initial composition of the Hercynian protolith. A geochemical data set summarizing 200 whole rock analyses testifies to a calc-alkaline magma differentiation producing a compositional range of tonalite and/or granodiorite to granite and leucocratic granite. Geochemical compositions combined with published isotope and age data suggest dominant I-type protoliths and mixed magma sources including crustal and mantle material, and distinguish between older granitoids of volcanic-arc affinity and probably younger ones of late or post-collision origin.

Organic Chemistry in Space

NASA Technical Reports Server (NTRS)

Charnley, Steven

2009-01-01

Astronomical observations, theoretical modeling, laboratory simulation and analysis of extraterrestrial material have enhanced our knowledge of the inventory of organic matter in the interstellar medium (ISM) and on small bodies such as comets and asteroids (Ehrenfreund & Charnley 2000). Comets, asteroids and their fragments, meteorites and interplanetary dust particles (IDPs), contributed significant amounts of extraterrestrial organic matter to the young Earth. This material degraded and reacted in a terrestrial prebiotic chemistry to form organic structures that may have served as building blocks for life on the early Earth. In this talk I will summarize our current understanding of the organic composition and chemistry of interstellar clouds. Molecules of astrobiological relevance include the building blocks of our genetic material: nucleic acids, composed of subunits such as N-heterocycles (purines and pyrimidines), sugars and amino acids. Signatures indicative of inheritance of pristine and modified interstellar material in comets and meteorites will also be discussed.

Effect of shelf aging on vibration transmissibility of anti-vibration gloves

PubMed Central

SHIBATA, Nobuyuki

2017-01-01

Anti-vibration gloves have been used in real workplaces to reduce vibration transmitted through hand-held power tools to the hand. Generally materials used for vibration attenuation in gloves are resilient materials composed of certain synthetic and/or composite polymers. The mechanical characteristics of the resilient materials used in anti-vibration gloves are prone to be influenced by environmental conditions such as temperature, humidity, and photo-irradiation, which cause material degradation and aging. This study focused on the influence of shelf aging on the vibration attenuation performance of air-packaged anti-vibration gloves following 2 yr of shelf aging. Effects of shelf aging on the vibration attenuation performance of anti-vibration gloves were examined according to the Japan industrial standard JIS T8114 test protocol. The findings indicate that shelf aging induces the reduction of vibration attenuation performance in air-packaged anti-vibration gloves. PMID:28978817

Cutin from agro-waste as a raw material for the production of bioplastics.

PubMed

Heredia-Guerrero, José A; Heredia, Antonio; Domínguez, Eva; Cingolani, Roberto; Bayer, Ilker S; Athanassiou, Athanassia; Benítez, José J

2017-11-09

Cutin is the main component of plant cuticles constituting the framework that supports the rest of the cuticle components. This biopolymer is composed of esterified bi- and trifunctional fatty acids. Despite its ubiquity in terrestrial plants, it has been underutilized as raw material due to its insolubility and lack of melting point. However, in recent years, a few technologies have been developed to obtain cutin monomers from several agro-wastes at an industrial scale. This review is focused on the description of cutin properties, biodegradability, chemical composition, processability, abundance, and the state of art of the fabrication of cutin-based materials in order to evaluate whether this biopolymer can be considered a source for the production of renewable materials. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

A universal cooperative assembly-directed method for coating of mesoporous TiO2 nanoshells with enhanced lithium storage properties

PubMed Central

Guan, Bu Yuan; Yu, Le; Li, Ju; Lou, Xiong Wen (David)

2016-01-01

TiO2 is exceptionally useful, but it remains a great challenge to develop a universal method to coat TiO2 nanoshells on different functional materials. We report a one-pot, low-temperature, and facile method that can rapidly form mesoporous TiO2 shells on various inorganic, organic, and inorganic-organic composite materials, including silica-based, metal, metal oxide, organic polymer, carbon-based, and metal-organic framework nanomaterials via a cooperative assembly-directed strategy. In constructing hollow, core-shell, and yolk-shell geometries, both amorphous and crystalline TiO2 nanoshells are demonstrated with excellent control. When used as electrode materials for lithium ion batteries, these crystalline TiO2 nanoshells composed of very small nanocrystals exhibit remarkably long-term cycling stability over 1000 cycles. The electrochemical properties demonstrate that these TiO2 nanoshells are promising anode materials. PMID:26973879

Improving Students' Memory for Musical Compositions and Their Composers: Mneme that Tune!

ERIC Educational Resources Information Center

Carney, Russell N.; Levin, Joel R.

2007-01-01

Students enrolled in music appreciation and music history courses may find it difficult to remember composers' names and the titles of their compositions--particularly when retrieval is prompted by corresponding classical music themes. We sought to develop and validate a mnemonic approach in which musical themes were first recoded as more concrete…

Possible sources of H2 to H2O enrichment at evaporation of parent chondritic material

NASA Technical Reports Server (NTRS)

Makalkin, A. B.; Dorofeyeva, V. A.; Vityazev, A. V.

1993-01-01

One of the results obtained from thermodynamic simulation of recondensation of the source chondritic material is that at 1500-1800 K it's possible to form iron-rich olivine by reaction between enstatite, metallic iron and water vapor in the case of (H2O)/(H2) approximately equal to 0.1. This could be reached if the gas depletion in hydrogen is 200-300 times relative to solar abundance. To get this range of depletion one needs some source material more rich in hydrogen than the carbonaceous CI material which is the richest in volatiles among chondrites. In the case of recondensation at impact heating and evaporation of colliding planetesimals composed of CI material, we obtain insufficiently high value of (H2)/(H2O) ratio. In the present paper we consider some possible source materials and physical conditions necessary to reach gas composition with (H2)/(H2O) approximately 10 at high temperature.

The Effects of Diet Calcium, Protein and Acidity on Calcium Retention in the Rat, Particularly as Related to the Inner and Outer Surfaces of Tubular Bone: A Possible Model for the Treatment or Prevention of Osteoporosis

DTIC Science & Technology

1979-10-01

transformed, by dissolution and reprecipitation, Into the crystalline constituent (85). It has also been suggested that crystalline hydroxyapatite ...a Ca:P molar ratio of 8:6), and finally hydroxyapatite (115). The apatites of bone are primarily hydroxvapatite which has the composition Ca 1 0 (P0...Thus bone always contains a large variety of materials other than those which compose hydroxyapatite . ____ ____ ___..~rr? - -- lt- - -11- The amount

Solution-grown silicon nanowires for lithium-ion battery anodes.

PubMed

Chan, Candace K; Patel, Reken N; O'Connell, Michael J; Korgel, Brian A; Cui, Yi

2010-03-23

Composite electrodes composed of silicon nanowires synthesized using the supercritical fluid-liquid-solid (SFLS) method mixed with amorphous carbon or carbon nanotubes were evaluated as Li-ion battery anodes. Carbon coating of the silicon nanowires using the pyrolysis of sugar was found to be crucial for making good electronic contact to the material. Using multiwalled carbon nanotubes as the conducting additive was found to be more effective for obtaining good cycling behavior than using amorphous carbon. Reversible capacities of 1500 mAh/g were observed for 30 cycles.

New composite thixotropic hydrogel composed of a polymer hydrogelator and a nanosheet

NASA Astrophysics Data System (ADS)

Ohsedo, Yutaka; Oono, Masashi; Saruhashi, Kowichiro; Watanabe, Hisayuki; Miyamoto, Nobuyoshi

2017-12-01

A composite gel composed of a water-soluble aromatic polyamide hydrogelator and the nanosheet Laponite®, a synthetic layered silicate, was produced and found to exhibit thixotropic behaviour. Whereas the composite gel contains the gelator at the same concentration as the molecular gel made by the gelator only, the composite gel becomes a softer thixotropic gel compared to the molecular gel made by the gelator only. The reason for this could be that bundles of polymer gelator may be loosened and the density of the polymer network increased in the presence of Laponite.

New composite thixotropic hydrogel composed of a polymer hydrogelator and a nanosheet

PubMed Central

Oono, Masashi; Saruhashi, Kowichiro; Watanabe, Hisayuki; Miyamoto, Nobuyoshi

2017-01-01

A composite gel composed of a water-soluble aromatic polyamide hydrogelator and the nanosheet Laponite®, a synthetic layered silicate, was produced and found to exhibit thixotropic behaviour. Whereas the composite gel contains the gelator at the same concentration as the molecular gel made by the gelator only, the composite gel becomes a softer thixotropic gel compared to the molecular gel made by the gelator only. The reason for this could be that bundles of polymer gelator may be loosened and the density of the polymer network increased in the presence of Laponite. PMID:29308249

Strain analysis of nanowire interfaces in multiscale composites

NASA Astrophysics Data System (ADS)

Malakooti, Mohammad H.; Zhou, Zhi; Spears, John H.; Shankwitz, Timothy J.; Sodano, Henry A.

2016-04-01

Recently, the reinforcement-matrix interface of fiber reinforced polymers has been modified through grafting nanostructures - particularly carbon nanotubes and ZnO nanowires - on to the fiber surface. This type of interface engineering has made a great impact on the development of multiscale composites that have high stiffness, interfacial strength, toughness, and vibrational damping - qualities that are mutually exclusive to a degree in most raw materials. Although the efficacy of such nanostructured interfaces has been established, the reinforcement mechanisms of these multiscale composites have not been explored. Here, strain transfer across a nanowire interphase is studied in order to gain a heightened understanding of the working principles of physical interface modification and the formation of a functional gradient. This problem is studied using a functionally graded piezoelectric interface composed of vertically aligned lead zirconate titanate nanowires, as their piezoelectric properties can be utilized to precisely control the strain on one side of the interface. The displacement and strain across the nanowire interface is captured using digital image correlation. It is demonstrated that the material gradient created through nanowires cause a smooth strain transfer from reinforcement phase into matrix phase that eliminates the stress concentration between these phases, which have highly mismatched elasticity.

Sea urchin-likeNiCoO2@C nanocompositesforLi-ionbatteries and supercapacitors

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

Liang, Jin; Xi, Kai; Tan, Guoqiang

The rational construction of battery electrode architecture that offers both high energy and power densities on a gravimetric and volumetric basis is a critical concern but achieving this aim is beset by many fundamental and practical challenges. Here we report a new sea urchin-like NiCoO2@C composite electrode architecture composed of NiCoO2 nanosheets grown on hollow concave carbon disks. Such a unique structural design not only preserves all the advantages of hollow structures but also increases the packing density of the active materials. NiCoO2 nanosheets grown on carbon disks promote a high utilization of active materials in redox reactions by reducingmore » the path length for Li+ ions and for electron transfer. Meanwhile, the hollow concave carbon not only reduces the volume change, but also improves the volumetric energy density of the entire composite electrode. As a result, the nanocomposites exhibit superior electrochemical performance measured in terms of high capacity/capacitance, stable cycling performance and good rate capability in both Li-ion battery and supercapacitor applications. Such nanostructured composite electrode may also have great potential for application in other electrochemical devices.« less

Experimental Research of FRP Composite Tube Confined Steel-reinforced Concrete Stub Columns Under Axial Compression

NASA Astrophysics Data System (ADS)

Wang, Ji Zhong; Cheng, Lu; Wang, Xin Pei

2018-06-01

A new column of FRP composite tube confined steel-reinforced concrete (FTCSRC) column was proposed. This paper elaborates on laboratorial and analytical studies on the behavior of FCTSRC columns subjected to axial compressive load. Eight circular FTCSRC stub columns and one circular steel tube confined concrete (STCC) stub column were tested to investigate the failure mode and axial compression performance of circular FTCRSC columns. Parametric analysis was implemented to inquire the influence of confinement material (CFRP-steel tube or CFRP-GFRP tube), internal steel and CFRP layers on the ultimate load capacity. CFRP-steel composite tube was composed of steel tube and CFRP layer which was wrapped outside the steel tube, while CFRP-GFRP composite tube was composite of GFRP tube and CFRP layer. The test results indicate that the confinement effect of CFRP-steel tube is greatly superior to CFRP-GFRP tube. The ductility performance of steel tube confined high-strength concrete column can be improved obviously by encasing steel in the core concrete. Furthermore, with the increase in the layers of FRP wraps, the axial load capacity increases greatly.

Soft-matter composites with electrically tunable elastic rigidity

NASA Astrophysics Data System (ADS)

Shan, Wanliang; Lu, Tong; Majidi, Carmel

2013-08-01

We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium-indium-tin (Galinstan®) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy.

Bioactivity and structural properties of nanostructured bulk composites containing Nb2O5 and natural hydroxyapatite

NASA Astrophysics Data System (ADS)

Bonadio, T. G. M.; Sato, F.; Medina, A. N.; Weinand, W. R.; Baesso, M. L.; Lima, W. M.

2013-06-01

In this work, we investigate the bioactivity and structural properties of nanostructured bulk composites that are composed of Nb2O5 and natural hydroxyapatite (HAp) and are produced by mechanical alloying and powder metallurgy. X-ray diffraction and Raman spectroscopy data showed that the milling process followed by a heat treatment at 1000 °C induced chemical reactions along with the formation of the CaNb2O6, PNb9O25 and Ca3(PO4)2 phases. Rietveld refinement indicated significant changes in each phase weight fraction as a function of HAp concentration. These changes influenced the in vitro bioactivity of the material. XRD and FTIR analyses indicated that the composites exhibited bioactivity characteristics by forming a carbonated apatite layer when the composites were immersed in a simulated body fluid. The formed layers had a maximum thickness of 13 μm, as measured by confocal Raman spectroscopy and as confirmed by scanning electron microscopy. The results of this work suggest that the tested bulk composites are promising biomaterials for use in implants.

Interfacial effect on physical properties of composite media: Interfacial volume fraction with non-spherical hard-core-soft-shell-structured particles.

PubMed

Xu, Wenxiang; Duan, Qinglin; Ma, Huaifa; Chen, Wen; Chen, Huisu

2015-11-02

Interfaces are known to be crucial in a variety of fields and the interfacial volume fraction dramatically affects physical properties of composite media. However, it is an open problem with great significance how to determine the interfacial property in composite media with inclusions of complex geometry. By the stereological theory and the nearest-surface distribution functions, we first propose a theoretical framework to symmetrically present the interfacial volume fraction. In order to verify the interesting generalization, we simulate three-phase composite media by employing hard-core-soft-shell structures composed of hard mono-/polydisperse non-spherical particles, soft interfaces, and matrix. We numerically derive the interfacial volume fraction by a Monte Carlo integration scheme. With the theoretical and numerical results, we find that the interfacial volume fraction is strongly dependent on the so-called geometric size factor and sphericity characterizing the geometric shape in spite of anisotropic particle types. As a significant interfacial property, the present theoretical contribution can be further drawn into predicting the effective transport properties of composite materials.

Interfacial effect on physical properties of composite media: Interfacial volume fraction with non-spherical hard-core-soft-shell-structured particles

PubMed Central

Xu, Wenxiang; Duan, Qinglin; Ma, Huaifa; Chen, Wen; Chen, Huisu

2015-01-01

Interfaces are known to be crucial in a variety of fields and the interfacial volume fraction dramatically affects physical properties of composite media. However, it is an open problem with great significance how to determine the interfacial property in composite media with inclusions of complex geometry. By the stereological theory and the nearest-surface distribution functions, we first propose a theoretical framework to symmetrically present the interfacial volume fraction. In order to verify the interesting generalization, we simulate three-phase composite media by employing hard-core-soft-shell structures composed of hard mono-/polydisperse non-spherical particles, soft interfaces, and matrix. We numerically derive the interfacial volume fraction by a Monte Carlo integration scheme. With the theoretical and numerical results, we find that the interfacial volume fraction is strongly dependent on the so-called geometric size factor and sphericity characterizing the geometric shape in spite of anisotropic particle types. As a significant interfacial property, the present theoretical contribution can be further drawn into predicting the effective transport properties of composite materials. PMID:26522701

Embedded fragments from U.S. military personnel--chemical analysis and potential health implications.

PubMed

Centeno, José A; Rogers, Duane A; van der Voet, Gijsbert B; Fornero, Elisa; Zhang, Lingsu; Mullick, Florabel G; Chapman, Gail D; Olabisi, Ayodele O; Wagner, Dean J; Stojadinovic, Alexander; Potter, Benjamin K

2014-01-23

The majority of modern war wounds are characterized by high-energy blast injuries containing a wide range of retained foreign materials of a metallic or composite nature. Health effects of retained fragments range from local or systemic toxicities to foreign body reactions or malignancies, and dependent on the chemical composition and corrosiveness of the fragments in vivo. Information obtained by chemical analysis of excised fragments can be used to guide clinical decisions regarding the need for fragment removal, to develop therapeutic interventions, and to better anticipate future medical problems from retained fragment related injuries. In response to this need, a new U.S Department of Defense (DoD) directive has been issued requiring characterization of all removed fragments to provide a database of fragment types occurring in combat injuries. The objective of this study is to determine the chemical composition of retained embedded fragments removed from injured military personnel, and to relate results to histological findings in tissue adjacent to fragment material. We describe an approach for the chemical analysis and characterization of retained fragments and adjacent tissues, and include case examples describing fragments containing depleted uranium (DU), tungsten (W), lead (Pb), and non-metal foreign bodies composed of natural and composite materials. Fragments obtained from four patients with penetrating blast wounds to the limbs were studied employing a wide range of chemical and microscopy techniques. Available adjacent tissues from three of the cases were histologically, microscopically, and chemically examined. The physical and compositional properties of the removed foreign material surfaces were examined with energy dispersive x-ray fluorescence spectrometry (EDXRF), scanning electron microscopy (SEM), laser ablation inductively-coupled plasma mass-spectrometry (LA-ICP-MS), and confocal laser Raman microspectroscopy (CLRM). Quantitative chemical analysis of both fragments and available tissues was conducted employing ICP-MS. Over 800 fragments have been characterized and included as part of the Joint Pathology Center Embedded Fragment Registry. Most fragments were obtained from penetrating wounds sustained to the extremities, particularly soft tissue injuries. The majority of the fragments were primarily composed of a single metal such as iron, copper, or aluminum with traces of antimony, titanium, uranium, and lead. One case demonstrated tungsten in both the fragment and the connected tissue, together with lead. Capsular tissue and fragments from a case from the 1991 Kuwait conflict showed evidence of uranium that was further characterized by uranium isotopic ratios analysis to contain depleted uranium. The present study provides a systematic approach for obtaining a full chemical characterization of retained embedded fragments. Given the vast number of combat casualties with retained fragments, it is expected that fragment analysis will have significant implications for the optimal short and long-term care of wounded service members.

Embedded Fragments from U.S. Military Personnel—Chemical Analysis and Potential Health Implications

PubMed Central

Centeno, José A.; Rogers, Duane A.; van der Voet, Gijsbert B.; Fornero, Elisa; Zhang, Lingsu; Mullick, Florabel G.; Chapman, Gail D.; Olabisi, Ayodele O.; Wagner, Dean J.; Stojadinovic, Alexander; Potter, Benjamin K.

2014-01-01

Background: The majority of modern war wounds are characterized by high-energy blast injuries containing a wide range of retained foreign materials of a metallic or composite nature. Health effects of retained fragments range from local or systemic toxicities to foreign body reactions or malignancies, and dependent on the chemical composition and corrosiveness of the fragments in vivo. Information obtained by chemical analysis of excised fragments can be used to guide clinical decisions regarding the need for fragment removal, to develop therapeutic interventions, and to better anticipate future medical problems from retained fragment related injuries. In response to this need, a new U.S Department of Defense (DoD) directive has been issued requiring characterization of all removed fragments to provide a database of fragment types occurring in combat injuries. Objectives: The objective of this study is to determine the chemical composition of retained embedded fragments removed from injured military personnel, and to relate results to histological findings in tissue adjacent to fragment material. Methods: We describe an approach for the chemical analysis and characterization of retained fragments and adjacent tissues, and include case examples describing fragments containing depleted uranium (DU), tungsten (W), lead (Pb), and non-metal foreign bodies composed of natural and composite materials. Fragments obtained from four patients with penetrating blast wounds to the limbs were studied employing a wide range of chemical and microscopy techniques. Available adjacent tissues from three of the cases were histologically, microscopically, and chemically examined. The physical and compositional properties of the removed foreign material surfaces were examined with energy dispersive x-ray fluorescence spectrometry (EDXRF), scanning electron microscopy (SEM), laser ablation inductively-coupled plasma mass-spectrometry (LA-ICP-MS), and confocal laser Raman microspectroscopy (CLRM). Quantitative chemical analysis of both fragments and available tissues was conducted employing ICP-MS. Results: Over 800 fragments have been characterized and included as part of the Joint Pathology Center Embedded Fragment Registry. Most fragments were obtained from penetrating wounds sustained to the extremities, particularly soft tissue injuries. The majority of the fragments were primarily composed of a single metal such as iron, copper, or aluminum with traces of antimony, titanium, uranium, and lead. One case demonstrated tungsten in both the fragment and the connected tissue, together with lead. Capsular tissue and fragments from a case from the 1991 Kuwait conflict showed evidence of uranium that was further characterized by uranium isotopic ratios analysis to contain depleted uranium. Conclusions: The present study provides a systematic approach for obtaining a full chemical characterization of retained embedded fragments. Given the vast number of combat casualties with retained fragments, it is expected that fragment analysis will have significant implications for the optimal short and long-term care of wounded service members. PMID:24464236

New applications of carbon nanostructures in microbial fuel cells (MFC)

NASA Astrophysics Data System (ADS)

Kaca, W.; Żarnowiec, P.; Keczkowska, Justyna; Suchańska, M.; Czerwosz, E.; Kozłowski, M.

2014-11-01

In the studies presented we proposed a new application for nanocomposite carbon films (C-Pd). These films were evaluated as an anode material for Microbial Fuel Cells (MFCs) used for electrical current generation. The results of characterization of C-Pd films composed of carbon and palladium nanograins were obtained using the Physical Vapor Deposition (PVD) method. The film obtained by this method exhibits a multiphase structure composed of fullerene nanograins, amorphous carbon and palladium nanocrystals. Raman Spectroscopy (RS) and scanning electron microscopy (SEM) are used to characterize the chemical composition, morphology and topography of these films. We observed, for MFC with C-Pd anode, the highest electrochemical activity and maximal voltage density - 458 mV (20,8 mV/cm2) for Proteus mirabilis, 426 mV (19,4 mV/cm2) for Pseudomonas aeruginosa and 652 mV (29,6 mV/cm2) for sewage bacteria as the microbial catalyst.

Development and Characterization of a Rate-Dependent Three-Dimensional Macroscopic Plasticity Model Suitable for Use in Composite Impact Problems

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Carney, Kelly S.; DuBois, Paul; Hoffarth, Canio; Rajan, Subramaniam; Blankenhorn, Gunther

2015-01-01

Several key capabilities have been identified by the aerospace community as lacking in the material/models for composite materials currently available within commercial transient dynamic finite element codes such as LS-DYNA. Some of the specific desired features that have been identified include the incorporation of both plasticity and damage within the material model, the capability of using the material model to analyze the response of both three-dimensional solid elements and two dimensional shell elements, and the ability to simulate the response of composites composed with a variety of composite architectures, including laminates, weaves and braids. In addition, a need has been expressed to have a material model that utilizes tabulated experimentally based input to define the evolution of plasticity and damage as opposed to utilizing discrete input parameters (such as modulus and strength) and analytical functions based on curve fitting. To begin to address these needs, an orthotropic macroscopic plasticity based model suitable for implementation within LS-DYNA has been developed. Specifically, the Tsai-Wu composite failure model has been generalized and extended to a strain-hardening based orthotropic plasticity model with a non-associative flow rule. The coefficients in the yield function are determined based on tabulated stress-strain curves in the various normal and shear directions, along with selected off-axis curves. Incorporating rate dependence into the yield function is achieved by using a series of tabluated input curves, each at a different constant strain rate. The non-associative flow-rule is used to compute the evolution of the effective plastic strain. Systematic procedures have been developed to determine the values of the various coefficients in the yield function and the flow rule based on the tabulated input data. An algorithm based on the radial return method has been developed to facilitate the numerical implementation of the material model. The presented paper will present in detail the development of the orthotropic plasticity model and the procedures used to obtain the required material parameters. Methods in which a combination of actual testing and selective numerical testing can be combined to yield the appropriate input data for the model will be described. A specific laminated polymer matrix composite will be examined to demonstrate the application of the model.

Sintering of (Ni,Mg)(Al,Fe)2O4 Materials and their Corrosion Process in Na3AlF6-AlF3-K3AlF6 Electrolyte

NASA Astrophysics Data System (ADS)

Xu, Yibiao; Li, Yawei; Yang, Jianhong; Sang, Shaobai; Wang, Qinghu

2017-06-01

The application of ledge-free sidewalls in the Hall-Héroult cells can potentially reduce the energy requirement of aluminum production by about 30 pct (Nightingale et al. in J Eur Ceram, 33:2761-2765, 2013). However, this approach poses great material challenges since such sidewalls are in direct contact with corrosive electrolyte. In the present paper, (Ni,Mg)(Al,Fe)2O4 materials were prepared using fused magnesia, reactive alumina, nickel oxide, and iron oxide powders as the starting materials. The sintering behaviors of specimens as well as their corrosion resistance to molten electrolyte have been investigated by means of X-ray diffraction and scanning electron microscope. The results show that after firing at temperature ranging from 1673 K (1400 °C) up to 1873 K (1600 °C), all the specimens prepared are composed of single-phase (Ni,Mg)(Al,Fe)2O4 composite spinel, the lattice parameter of which increases with increasing Fe3+ ion concentration. Increasing the iron oxide content enhances densification of the specimens, which is accompanied by the formation of homogeneously distributed smaller pores in the matrix. The corrosion tests show that corrosion layers consist of fluoride and Ni(Al,Fe)2O4 composite spinel grains are produced in specimens with Fe/Al mole ratio no more than 1, whereas dense Ni(Al,Fe)2O4 composite spinel layers are formed on the surface of the specimens with Fe/Al mole ratio more than 1. The dense Ni(Al,Fe)2O4 composite spinel layers formed improve the corrosion resistance of the specimens by inhibiting the infiltration of electrolyte and hindering the chemical reaction between the specimen and electrolyte.

Multi-scale analysis and characterization of the ITER pre-compression rings

NASA Astrophysics Data System (ADS)

Foussat, A.; Park, B.; Rajainmaki, H.

2014-01-01

The toroidal field (TF) system of ITER Tokamak composed of 18 "D" shaped Toroidal Field (TF) coils during an operating scenario experiences out-of-plane forces caused by the interaction between the 68kA operating TF current and the poloidal magnetic fields. In order to keep the induced static and cyclic stress range in the intercoil shear keys between coils cases within the ITER allowable limits [1], centripetal preload is introduced by means of S2 fiber-glass/epoxy composite pre-compression rings (PCRs). Those PCRs consist in two sets of three rings, each 5 m in diameter and 337 × 288 mm in cross-section, and are installed at the top and bottom regions to apply a total resultant preload of 70 MN per TF coil equivalent to about 400 MPa hoop stress. Recent developments of composites in the aerospace industry have accelerated the use of advanced composites as primary structural materials. The PCRs represent one of the most challenging composite applications of large dimensions and highly stressed structures operating at 4 K over a long term life. Efficient design of those pre-compression composite structures requires a detailed understanding of both the failure behavior of the structure and the fracture behavior of the material. Due to the inherent difficulties to carry out real scale testing campaign, there is a need to develop simulation tools to predict the multiple complex failure mechanisms in pre-compression rings. A framework contract was placed by ITER Organization with SENER Ingenieria y Sistemas SA to develop multi-scale models representative of the composite structure of the Pre-compression rings based on experimental material data. The predictive modeling based on ABAQUS FEM provides the opportunity both to understand better how PCR composites behave in operating conditions and to support the development of materials by the supplier with enhanced performance to withstand the machine design lifetime of 30,000 cycles. The multi-scale stress analysis has revealed a complete picture of the stress levels within the fiber and the matrix regarding the static and fatigue performance of the rings structure including the presence of a delamination defect of critical size. The analysis results of the composite material demonstrate that the rings performance objectives under all loading and strength conditions are met.

Impregnation of Composite Materials: a Numerical Study

NASA Astrophysics Data System (ADS)

Baché, Elliott; Dupleix-Couderc, Chloé; Arquis, Eric; Berdoyes, Isabelle

2017-12-01

Oxide ceramic matrix composites are currently being developed for aerospace applications such as the exhaust, where the parts are subject to moderately high temperatures (≈ 700 ∘C) and oxidation. These composite materials are normally formed by, among other steps, impregnating a ceramic fabric with a slurry of ceramic particles. This impregnation process can be complex, with voids possibly forming in the fabric depending on the process parameters and material properties. Unwanted voids or macroporosity within the fabric can decrease the mechanical properties of the parts. In order to design an efficient manufacturing process able to impregnate the fabric well, numerical simulations may be used to design the process as well as the slurry. In this context, a tool is created for modeling different processes. Thétis, which solves the Navier-Stokes-Darcy-Brinkman equation using finite volumes, is expanded to take into account capillary pressures on the mesoscale. This formulation allows for more representativity than for Darcy's law (homogeneous preform) simulations while avoiding the prohibitive simulation times of a full discretization for the composing fibers at the representative elementary volume scale. The resulting tool is first used to investigate the effect of varying the slurry parameters on impregnation evolution. Two different processes, open bath impregnation and wet lay-up, are then studied with emphasis on varying their input parameters (e.g. inlet velocity).

Ultrafast Self-Healing Nanocomposites via Infrared Laser and Their Application in Flexible Electronics.

PubMed

Wu, Shuwen; Li, Jinhui; Zhang, Guoping; Yao, Yimin; Li, Gang; Sun, Rong; Wong, Chingping

2017-01-25

The continuous evolution toward flexible electronics with mechanical robust property and restoring structure simultaneously places high demand on a set of polymeric material substrate. Herein, we describe a composite material composed of a polyurethane based on Diels-Alder chemistry (PU-DA) covalently linked with functionalized graphene nanosheets (FGNS), which shows mechanical robust and infrared (IR) laser self-healing properties at ambient conditions and is therefore suitable for flexible substrate applications. The mechanical strength can be tuned by varying the amount of FGNS and breaking strength can reach as high as 36 MPa with only 0.5 wt % FGNS loading. On rupture, the initial mechanical properties are restored with more than 96% healing efficiency after 1 min irradiation time by 980 nm IR laser. Especially, this is the highest value of healing efficiency reported in the self-healable materials based on DA chemistry systems until now, and the composite exhibits a high volume resistivity up to 5.6 × 10 11 Ω·cm even the loading of FGNS increased to 1.0 wt %. Moreover, the conductivity of the broken electric circuit which was fabricated by silver paste drop-cast on the healable composite substrate was completely recovered via IR laser irradiating bottom substrate mimicking human skin. These results demonstrate that the FGNS-PU-DA nanocomposite can be used as self-healing flexible substrate for the next generation of intelligent flexible electronics.

The composition of precarity: 'emerging' composers' experiences of opportunity culture in contemporary classical music.

PubMed

Smith, Neil Thomas; Thwaites, Rachel

2018-02-28

This paper examines the precarious working lives of 'emerging' composers attempting to build a career in the world of new classical music in the UK. This topic is approached by considering the 'composition opportunity', success in which is seen as an important element in 'making it' in this sphere. We argue that such schemes in fact manifest a crucial tension in the nature of artistic labour, and are, at the very least, problematic in their function as conduits towards full professional identity. They may instead act to maintain the precarious working situation of composers in a neoliberal age. The working lives of artists are all too rarely illuminated, and new music composers are no exception; this survey of 47 emerging composers is the largest study of such individuals in the UK. © London School of Economics and Political Science 2018.

Markov Chain Analysis of Musical Dice Games

NASA Astrophysics Data System (ADS)

Volchenkov, D.; Dawin, J. R.

2012-07-01

A system for using dice to compose music randomly is known as the musical dice game. The discrete time MIDI models of 804 pieces of classical music written by 29 composers have been encoded into the transition matrices and studied by Markov chains. Contrary to human languages, entropy dominates over redundancy, in the musical dice games based on the compositions of classical music. The maximum complexity is achieved on the blocks consisting of just a few notes (8 notes, for the musical dice games generated over Bach's compositions). First passage times to notes can be used to resolve tonality and feature a composer.

Musical Markov Chains

NASA Astrophysics Data System (ADS)

Volchenkov, Dima; Dawin, Jean René

A system for using dice to compose music randomly is known as the musical dice game. The discrete time MIDI models of 804 pieces of classical music written by 29 composers have been encoded into the transition matrices and studied by Markov chains. Contrary to human languages, entropy dominates over redundancy, in the musical dice games based on the compositions of classical music. The maximum complexity is achieved on the blocks consisting of just a few notes (8 notes, for the musical dice games generated over Bach's compositions). First passage times to notes can be used to resolve tonality and feature a composer.

The effect of material choice on biofilm formation in a model warm water distribution system.

PubMed

Waines, Paul L; Moate, Roy; Moody, A John; Allen, Mike; Bradley, Graham

2011-11-01

Water distribution systems (WDS) are composed of a variety of materials and may harbour potential pathogens within surface-attached microbial biofilms. Biofilm formation on four plumbing materials, viz. copper, stainless steel 316 (SS316), ethylene propylene diene monomer (EPDM) and cross-linked polyethylene (PEX), was investigated using scanning electron microscope (SEM)/confocal microscopy, ATP-/culture-based analysis, and molecular analysis. Material 'inserts' were incorporated into a mains water fed, model WDS. All materials supported biofilm growth to various degrees. After 84 days, copper and SS316 showed no significant overall differences in terms of the level of biofilm formation observed, whilst PEX supported a significantly higher level of biofilm. EPDM exhibited gross contamination by a complex, multispecies biofilm, at a level significantly higher than was observed on the other materials, regardless of the analytical method used. PCR-DGGE analysis showed clear differences in the composition of the biofilm community on all materials after 84 days. The primary conclusion of this study has been to identify EPDM as a potentially unsuitable material for use as a major component in WDS.

Thermoelastic analysis of non-uniform pressurized functionally graded cylinder with variable thickness using first order shear deformation theory(FSDT) and perturbation method

NASA Astrophysics Data System (ADS)

Khoshgoftar, M. J.; Mirzaali, M. J.; Rahimi, G. H.

2015-11-01

Recently application of functionally graded materials(FGMs) have attracted a great deal of interest. These materials are composed of various materials with different micro-structures which can vary spatially in FGMs. Such composites with varying thickness and non-uniform pressure can be used in the aerospace engineering. Therefore, analysis of such composite is of high importance in engineering problems. Thermoelastic analysis of functionally graded cylinder with variable thickness under non-uniform pressure is considered. First order shear deformation theory and total potential energy approach is applied to obtain the governing equations of non-homogeneous cylinder. Considering the inner and outer solutions, perturbation series are applied to solve the governing equations. Outer solution for out of boundaries and more sensitive variable in inner solution at the boundaries are considered. Combining of inner and outer solution for near and far points from boundaries leads to high accurate displacement field distribution. The main aim of this paper is to show the capability of matched asymptotic solution for different non-homogeneous cylinders with different shapes and different non-uniform pressures. The results can be used to design the optimum thickness of the cylinder and also some properties such as high temperature residence by applying non-homogeneous material.

Bone Regeneration after Treatment with Covering Materials Composed of Flax Fibers and Biodegradable Plastics: A Histological Study in Rats

PubMed Central

Gedrange, Tomasz

2016-01-01

The aim of this study was to examine the osteogenic potential of new flax covering materials. Bone defects were created on the skull of forty rats. Materials of pure PLA and PCL and their composites with flax fibers, genetically modified producing PHB (PLA-transgen, PCL-transgen) and unmodified (PLA-wt, PCL-wt), were inserted. The skulls were harvested after four weeks and subjected to histological examination. The percentage of bone regeneration by using PLA was less pronounced than after usage of pure PCL in comparison with controls. After treatment with PCL-transgen, a large amount of new formed bone could be found. In contrast, PCL-wt decreased significantly the bone regeneration, compared to the other tested groups. The bone covers made of pure PLA had substantially less influence on bone regeneration and the bone healing proceeded with a lot of connective tissue, whereas PLA-transgen and PLA-wt showed nearly comparable amount of new formed bone. Regarding the histological data, the hypothesis could be proposed that PCL and its composites have contributed to a higher quantity of the regenerated bone, compared to PLA. The histological studies showed comparable bone regeneration processes after treatment with tested covering materials, as well as in the untreated bone lesions. PMID:27597965

Bone Regeneration after Treatment with Covering Materials Composed of Flax Fibers and Biodegradable Plastics: A Histological Study in Rats.

PubMed

Gredes, Tomasz; Kunath, Franziska; Gedrange, Tomasz; Kunert-Keil, Christiane

2016-01-01

The aim of this study was to examine the osteogenic potential of new flax covering materials. Bone defects were created on the skull of forty rats. Materials of pure PLA and PCL and their composites with flax fibers, genetically modified producing PHB (PLA-transgen, PCL-transgen) and unmodified (PLA-wt, PCL-wt), were inserted. The skulls were harvested after four weeks and subjected to histological examination. The percentage of bone regeneration by using PLA was less pronounced than after usage of pure PCL in comparison with controls. After treatment with PCL-transgen, a large amount of new formed bone could be found. In contrast, PCL-wt decreased significantly the bone regeneration, compared to the other tested groups. The bone covers made of pure PLA had substantially less influence on bone regeneration and the bone healing proceeded with a lot of connective tissue, whereas PLA-transgen and PLA-wt showed nearly comparable amount of new formed bone. Regarding the histological data, the hypothesis could be proposed that PCL and its composites have contributed to a higher quantity of the regenerated bone, compared to PLA. The histological studies showed comparable bone regeneration processes after treatment with tested covering materials, as well as in the untreated bone lesions.

Lightweight, fire-retardant, crashworthy aircraft seat cushioning

NASA Technical Reports Server (NTRS)

Haslim, Leonard A.; Mcdonough, Paul T.

1991-01-01

A two page discussion of non-aerospace seating applications and the design of NASA's safety seat cushioning (SSC) is presented. The SSC was designed for both safety and comfort in order to replace polyurethane cushioning which is flammable and produces lethal fumes upon combustion. The SSC is composed of advanced fabric reinforced composites and is lightweight, fire-retardent, and crashworthy. The seat design consists of central elliptical tubular spring supports made of fire-resistant and fatigue-durable composites surrounded by a fire-blocking sheath. The cushioning is made crashworthy by incorporating energy-absorbing, viscoelastic layers between the nested, elliptical-hoop springs. The design is intended to provide comfortable seating that meets aircraft-loading requirements without using the conventional polyurethane materials. The designs of an aircraft seat and structural components of the SSC are also presented.

Extraction of composite visual objects from audiovisual materials

NASA Astrophysics Data System (ADS)

Durand, Gwenael; Thienot, Cedric; Faudemay, Pascal

1999-08-01

An effective analysis of Visual Objects appearing in still images and video frames is required in order to offer fine grain access to multimedia and audiovisual contents. In previous papers, we showed how our method for segmenting still images into visual objects could improve content-based image retrieval and video analysis methods. Visual Objects are used in particular for extracting semantic knowledge about the contents. However, low-level segmentation methods for still images are not likely to extract a complex object as a whole but instead as a set of several sub-objects. For example, a person would be segmented into three visual objects: a face, hair, and a body. In this paper, we introduce the concept of Composite Visual Object. Such an object is hierarchically composed of sub-objects called Component Objects.

An autonomously electrically self-healing liquid metal-elastomer composite for robust soft-matter robotics and electronics.

PubMed

Markvicka, Eric J; Bartlett, Michael D; Huang, Xiaonan; Majidi, Carmel

2018-07-01

Large-area stretchable electronics are critical for progress in wearable computing, soft robotics and inflatable structures. Recent efforts have focused on engineering electronics from soft materials-elastomers, polyelectrolyte gels and liquid metal. While these materials enable elastic compliance and deformability, they are vulnerable to tearing, puncture and other mechanical damage modes that cause electrical failure. Here, we introduce a material architecture for soft and highly deformable circuit interconnects that are electromechanically stable under typical loading conditions, while exhibiting uncompromising resilience to mechanical damage. The material is composed of liquid metal droplets suspended in a soft elastomer; when damaged, the droplets rupture to form new connections with neighbours and re-route electrical signals without interruption. Since self-healing occurs spontaneously, these materials do not require manual repair or external heat. We demonstrate this unprecedented electronic robustness in a self-repairing digital counter and self-healing soft robotic quadruped that continue to function after significant damage.

EASY SYNTHESIS OF Li4Ti5O12/C MICROSPHERES CONTAINING NANOPARTICLES AS ANODE MATERIAL FOR HIGH-RATE Li-ION BATTERIES

NASA Astrophysics Data System (ADS)

Zheng, Xiaodong; Dong, Lina; Dong, Chenchu

2014-01-01

A microspherical Li4Ti5O12/C composite composed of interconnected nanoparticles with BP-2000 carbon black as carbon source is synthesized for use as an anode material in high-power lithium-ion batteries. The composite is prepared through precursor pretreatment including pre-sintering, ball-milling, and spray-drying. The structure, size and surface morphology of the as-prepared particles are investigated by X-ray diffraction and scanning electron microscopy. Results show that the obtained material has a microspherical morphology consisting of nanosized prime particles with compact structure. The precursor pretreatment effectively reduced the agglomeration of the prime particles caused by high temperature sintering and led to a more uniform distribution of BP-2000 on the surface of prime particles generating highly efficient conductive network. The specific capacity of the electrode at 20 C rate is 131 mAh g-1 and the loss of capacity is less than 2% after the 60 variation cycles (from 1 C to 20 C and back to 1 C). This excellent performance is attributed to the effective conductive network between the prime particles and the reduction of the lithium-ion diffusion pathway.

Children Composing and the Tonal Idiom

ERIC Educational Resources Information Center

Roels, Johanna Maria; Van Petegem, Peter

2016-01-01

Existing studies have demonstrated how children compose, experiment and use their imagination within the conventions of the tonal idiom with functional harmony. However, one area of research that has hardly been explored is how tonality emerges in the compositions of children who compose by transforming their own non-musical ideas, such as their…

The Contexts of Composing: A Dynamic Scene with Movable Centers.

ERIC Educational Resources Information Center

Wiley, Mark L.

An examination of the transformations that the concept of genius undergoes when viewed through the apparently incommensurable expressivistic and social views of composing helps to reconcile phenomenologically objective descriptions of composing with value-laden descriptions of the self in the act of writing. When the description of composition is…

Smart Materials for Advanced Applications: Self-Decontaminating Polymers, Photofunctional Composites, and Electroconductive Fibers

NASA Astrophysics Data System (ADS)

Little, Brian Kevin

2011-12-01

Materials capable of providing multifunctional properties controllable by some external stimulus (pH, light, temperature, etc) are highly desirable and obtainable given recent advancements in material science. Development of these so called "Smart" materials spanned across many disciplines of science with applications in industrial areas such as medical, military, security, and environmental. Furthermore, next-generation materials require the ability to not only sense/respond to changes in their external/internal environment, but process information in regards to these changes and adapt accordingly in a dynamic fashion, autonomously, so called "Intelligent" materials. Findings reported in this manuscript detail the synthesis, characterization, and application of smart materials in the following three areas: (1) self-cleaning polymers (2) photoresponsive composites and (3) electroconductive fibers. Self-Cleaning Polymers: Self-decontaminating polymers are unique materials capable of degrading toxic organic chemicals (TOCs). Barriers composed of or coated with our photochemical reactive polymer matrix could be applied to multiple surfaces for defense against TOCs; for example, military garments for protection against chemical warfare agents. This study investigates conditions necessary for formation of peroxides via O2 reduction induced by long-lived, strongly reducing benzophenyl ketyl (BPK) polymer radicals. Photolysis of aqueous solutions composed of sulphonated poly(ether etherketone), SPEEK, and poly(vinyl alcohol), PVA lead to the formation of the BPK radicals. Experiments investigate the formation and decomposition of peroxides in aqueous solutions of SPEEK/PVA under photolysis. Photofunctional Composites: Photoresponsive nanoporous (PN) films and powders were studied and evaluated as possible additives to sensitize the initiation of CH3NO2 via a mechanism involving coalescence of reaction sites. Such materials consist of a 3-D mesoporous silica framework possessing open interconnected pores. Attached to the pore walls are azobenzene ligands that undergo trans to cis isomerization upon exposure to 350--360 nm photons; the reverse reaction occurs with heat or under illumination with lambda > 420 nm. PN films were studied to ascertain the mass transport properties for the filling/releasing of CH 3NO2 from within the pores of the films in the absence/presence of UV-Vis light. PN powders were evaluated for pore morphology, ligand mobility, and particle size and shape in order to determine their ability to be utilized as an effective sensitizing agent. Electroconductive Fibers: This study investigates electroless and electrochemical techniques for purposes of producing highly conductive metal coatings on the surface of high strength fibers. Metallized fibers were envisioned to be utilized as high strength low weight tethers for space applications. Findings suggest that these materials could be valuable as components within "Intelligent" textiles, but, at present, not suitable for conditions witnessed in space (high energy UV irradiation, Atomic Oxygen, etc). Kevlar fibers were coated utilizing an electroless and then electrochemical deposition processes. Metallized fibers were evaluated for their resistivity, power output, tensile strength, uniform coverage, and mass gain. Presented in this section are the results of such measurements.

High dose neutron irradiations of Hi-Nicalon Type S silicon carbide composites, Part 1: Microstructural evaluations

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

Perez-Bergquist, Alex G.; Nozawa, Takashi; Shih, Chunghao Phillip

Over the past decade, significant progress has been made in the development of silicon carbide (SiC) composites, composed of near-stoichiometric SiC fibers embedded in a crystalline SiC matrix, to the point that such materials can now be considered nuclear grade. Recent neutron irradiation studies of Hi-Nicalon Type S SiC composites showed excellent radiation response at damage levels of 30-40 dpa at temperatures of 300-800 °C. However, more recent studies of these same fiber composites irradiated to damage levels of >70 dpa at similar temperatures showed a marked decrease in ultimate flexural strength, particularly at 300 °C. Here, electron microscopy ismore » used to analyze the microstructural evolution of these irradiated composites in order to investigate the cause of the degradation. While minimal changes were observed in Hi-Nicalon Type S SiC composites irradiated at 800 °C, substantial microstructural evolution is observed in those irradiated at 300° C. Furthermore, carbonaceous particles in the fibers grew by 25% compared to the virgin case, and severe cracking occurred at interphase layers.« less

Synthesis of Ordered Mesoporous CuO/CeO2 Composite Frameworks as Anode Catalysts for Water Oxidation

PubMed Central

Markoulaki, Vassiliki Ι.; Papadas, Ioannis T.; Kornarakis, Ioannis; Armatas, Gerasimos S.

2015-01-01

Cerium-rich metal oxide materials have recently emerged as promising candidates for the photocatalytic oxygen evolution reaction (OER). In this article, we report the synthesis of ordered mesoporous CuO/CeO2 composite frameworks with different contents of copper(II) oxide and demonstrate their activity for photocatalytic O2 production via UV-Vis light-driven oxidation of water. Mesoporous CuO/CeO2 materials have been successfully prepared by a nanocasting route, using mesoporous silica as a rigid template. X-ray diffraction, electron transmission microscopy and N2 porosimetry characterization of the as-prepared products reveal a mesoporous structure composed of parallel arranged nanorods, with a large surface area and a narrow pore size distribution. The molecular structure and optical properties of the composite materials were investigated with Raman and UV-Vis/NIR diffuse reflectance spectroscopy. Catalytic results indicated that incorporation of CuO clusters in the CeO2 lattice improved the photochemical properties. As a result, the CuO/CeO2 composite catalyst containing ~38 wt % CuO reaches a high O2 evolution rate of ~19.6 µmol·h−1 (or 392 µmol·h−1·g−1) with an apparent quantum efficiency of 17.6% at λ = 365 ± 10 nm. This OER activity compares favorably with that obtained from the non-porous CuO/CeO2 counterpart (~1.3 µmol·h−1) and pure mesoporous CeO2 (~1 µmol·h−1). PMID:28347106

A Plasmonic Colloidal Photocatalyst Composed of a Metal-Organic Framework Core and a Gold/Anatase Shell for Visible-Light-Driven Wastewater Purification from Antibiotics and Hydrogen Evolution.

PubMed

Tilgner, Dominic; Kempe, Rhett

2017-03-02

Porous coordination polymers (PCP) or metal- organic frameworks (MOF) are promising materials for the generation of photocatalytically active composite materials. Here, a novel synthesis concept is reported, which permits the formation of PCP/MOF-core-Au/anatase-shell materials. These materials are photocatalysts for wastewater purification and hydrogen generation from water under visible-light illumination. MIL-101 (Cr) is utilized as the core material, which directs the size of the core-shell compound and ensures the overall stability. In addition, its excellent reversible large molecule sorption behavior allows the materials synthesis. The crystalline anatase shell is generated stepwise under mild conditions using titanium(IV) isopropoxide as a precursor. The high degree of control of the vapor phase deposition process permits the precise anatase shell formation. The generation of plasmonic active gold particles on the TiO 2 shell leads to an efficient material for visible-light-driven photocatalysis with a higher activity than gold-decorated P25 (Degussa). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multiple Interfacial Fe3O4@BaTiO3/P(VDF-HFP) Core-Shell-Matrix Films with Internal Barrier Layer Capacitor (IBLC) Effects and High Energy Storage Density.

PubMed

Zhou, Ling; Fu, Qiuyun; Xue, Fei; Tang, Xiahui; Zhou, Dongxiang; Tian, Yahui; Wang, Geng; Wang, Chaohong; Gou, Haibo; Xu, Lei

2017-11-22

Flexible nanocomposites composed of high dielectric constant fillers and polymer matrix have shown great potential for electrostatic capacitors and energy storage applications. To obtain the composited material with high dielectric constant and high breakdown strength, multi-interfacial composited particles, which composed of conductive cores and insulating shells and possessed the internal barrier layer capacitor (IBLC) effect, were adopted as fillers. Thus, Fe 3 O 4 @BaTiO 3 core-shell particles were prepared and loaded into the poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) polymer matrix. As the mass fraction of core-shell fillers increased from 2.5 wt % to 30 wt %, the dielectric constant of the films increased, while the loss tangent remained at a low level (<0.05 at 1 kHz). Both high electric displacement and high electric breakdown strength were achieved in the films with 10 wt % core-shell fillers loaded. The maximum energy storage density of 7.018 J/cm 3 was measured at 2350 kV/cm, which shows significant enhancement than those of the pure P(VDF-HFP) films and analogous composited films with converse insulating-conductive core-shell fillers. A Maxwell-Wagner capacitor model was also adopted to interpret the efficiency of IBLC effects on the suppressed loss tangent and the superior breakdown strength. This work explored an effective approach to prepare dielectric nanocomposites for energy storage applications experimentally and theoretically.

3 V omni-directionally stretchable one-body supercapacitors based on a single ion-gel matrix and carbon nanotubes.

PubMed

Kim, Wonbin; Kim, Woong

2016-06-03

Stretchable supercapacitors often have laminated structures consisting of electrode, electrolyte, and supporting layers. Since the layers are likely to be composed of different materials, delamination is a major cause of failure upon stretching. In this study, we demonstrate delamination-free stretchable supercapacitors where all the component layers are prepared with a single matrix, which is composed of a polymer, poly(vinylidene fluoride-hexafluoropropylene) and an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Since the ionic liquid in the composite plays a role as both an electrolyte and a plasticizer, this composite can be used as an electrolyte and a supporting layer in the stretchable supercapacitor. The electrode layer can be fabricated by incorporating carbon nanotubes in the common matrix. Then, all the layers can be seamlessly fused into one body by dissolving the surface of the composite with acetone, which evaporates after the integration, leaving no borders between the layers. This one-body stretchable supercapacitor not only has high durability against repetitive stretches but also is stretchable in all directions. This feature clearly distinguishes them from conventional stretchable supercapacitors fabricated using buckled structures, which are stretchable only in one or two directions. Moreover, this supercapacitor has high cell voltage (∼3 V) owing to the ionic liquid-based gel electrolytes. Our demonstration of isotropically stretchable high-durability supercapacitors may have a great implication in the development of stretchable energy storage devices for real applications.

Innovative energy absorbing devices based on composite tubes

NASA Astrophysics Data System (ADS)

Tiwari, Chandrashekhar

Analytical and experimental study of innovative load limiting and energy absorbing devices are presented here. The devices are based on composite tubes and can be categorized in to two groups based upon the energy absorbing mechanisms exhibited by them, namely: foam crushing and foam fracturing. The device based on foam crushing as the energy absorbing mechanism is composed of light weight elastic-plastic foam filling inside an angle ply composite tube. The tube is tailored to have a high Poisson’s ratio (>20). Upon being loaded the device experiences large transverse contraction resulting in rapid decrease in diameter. At a certain axial load the foam core begins to crush and energy is dissipated. This device is termed as crush tube device. The device based upon foam shear fracture as the energy absorbing mechanism involves an elastic-plastic core foam in annulus of two concentric extension-twist coupled composite tubes with opposite angles of fibers. The core foam is bonded to the inner and outer tube walls. Upon being loaded axially, the tubes twist in opposite directions and fracture the core foam in out of plane shear and thus dissipate the energy stored. The device is termed as sandwich core device (SCD). The devices exhibit variations in force-displacement characteristics with changes in design and material parameters, resulting in wide range of energy absorption capabilities. A flexible matrix composite system was selected, which was composed of high stiffness carbon fibers as reinforcements in relatively low stiffness polyurethane matrix, based upon large strain to failure capabilities and large beneficial elastic couplings. Linear and non-linear analytical models were developed encapsulating large deformation theory of the laminated composite shells (using non-linear strain energy formulation) to the fracture mechanics of core foam and elastic-plastic deformation theory of the foam filling. The non-linear model is capable of including material and geometric nonlinearities that arise from large deformation and fiber reorientation. Developed non-linear analysis predicts the behavior of extension-twist coupled and angle ply flexible matrix composite tubes under multi-axial loadings. The predicted results show close correlation with experimental findings. It was also found that these devices exhibit variations with respect to rate of loading. It was found that the novel energy absorbing devices are capable of providing 4-5 times higher specific energy absorption (SEA) than currently used devices for similar purposes (such as wire bender which has SEA of 3.6 J/g).

Densification control and analysis of outer shell of new high-temperature vacuum insulated composite

NASA Astrophysics Data System (ADS)

Wang, Yang; Chen, Zhaofeng; Jiang, Yun; Yu, Shengjie; Xu, Tengzhou; Li, Binbin; Chen, Zhou

2017-11-01

A novel high temperature vacuum insulated composite with low thermal conductivity composed of SiC foam core material and sealing outer shell is discussed, which will have a great potential to be used as thermal protection system material. In this composite, the outer shell is the key to maintain its internal vacuum, which is consisted of 2.5D C/C and SiC coating. So the densification processes of outer shell, including 2.5D braiding process, chemical vapor infiltration (CVI) pyrolytic carbon (PyC) process, polymer infiltration and pyrolysis (PIP) glassy carbon (GC) process and chemical vapor deposition (CVD) SiC process, are focused in this paper. The measuring result of the gas transmission quantity of outer shell is only 0.14 cm3/m2 · d · Pa after 5 times CVD processes, which is two order of magnitude lower than that sample deposited one time. After 10 times thermal shock cycles, the gas transmission quantity increases to 1.2 cm3/m2 · d · Pa. The effective thermal conductivity of high temperature vacuum insulated composite ranged from 0.19 W m-1 K-1 to 0.747 W m-1 K-1 within the temperature from 20 °C to 900 °C. Even after 10 thermal shock cycles, the variation of the effective thermal conductivity is still consistent with that without treatments.

Improving bioactivity of inert bioceramics by a novel Mg-incorporated solution treatment

NASA Astrophysics Data System (ADS)

Dehestani, Mahdi; Zemlyanov, Dmitry; Adolfsson, Erik; Stanciu, Lia A.

2017-12-01

Zirconia/alumina ceramics possess outstanding mechanical properties for dental and orthopedic applications, but due to their poor surface bioactivities they exhibit a weak bone-bonding ability. This work proposes an effective 30-min solution treatment which could successfully induce formation of bone-like apatite on the surface of 3Y-TZP and a ternary composite composed of yttria-stabilized zirconia, ceria-stabilized zirconia, and alumina (35 vol% 3Y-TZP + 35 vol% 12Ce-TZP + 30 vol% Al2O3) after 3 weeks immersion in simulated body fluid (SBF). XRD was used for phase identification in the ceramic materials. The influence of solution treatment on the surface chemistry and its role on apatite formation were investigated via SEM, EDS and XPS. In vitro apatite-forming ability for the solution-treated and untreated samples of the composite and individual substrates of 3Y-TZP, 12Ce-TZP, and Al2O3 was evaluated by immersion in SBF. Apatite crystals were formed only on 3Y-TZP and composite substrates, implying that it is mainly the 3Y-TZP constituent that contributes to the bioactivity of the composite. Further, it was found from the XPS analysis that the zirconia material with higher phase stability (12Ce-TZP) produced less Zrsbnd OH functional groups on its surface after solution treatment which accounts for its weaker bioactivity compared to 3Y-TZP.

Metal-Organic Frameworks Derived Okra-like SnO2 Encapsulated in Nitrogen-Doped Graphene for Lithium Ion Battery.

PubMed

Zhou, Xiangyang; Chen, Sanmei; Yang, Juan; Bai, Tao; Ren, Yongpeng; Tian, Hangyu

2017-04-26

A facile process is developed to prepare SnO 2 -based composites through using metal-organic frameworks (MOFs) as precursors. The nitrogen-doped graphene wrapped okra-like SnO 2 composites (SnO 2 @N-RGO) are successfully synthesized for the first time by using Sn-based metal-organic frameworks (Sn-MOF) as precursors. When utilized as an anode material for lithium-ion batteries, the SnO 2 @N-RGO composites possess a remarkably superior reversible capacity of 1041 mA h g -1 at a constant current of 200 mA g -1 after 180 charge-discharge processes and excellent rate capability. The excellent performance can be primarily ascribed to the unique structure of 1D okra-like SnO 2 in SnO 2 @N-RGO which are actually composed of a great number of SnO 2 primary crystallites and numerous well-defined internal voids, can effectively alleviate the huge volume change of SnO 2 , and facilitate the transport and storage of lithium ions. Besides, the structural stability acquires further improvement when the okra-like SnO 2 are wrapped by N-doped graphene. Similarly, this synthetic strategy can be employed to synthesize other high-capacity metal-oxide-based composites starting from various metal-organic frameworks, exhibiting promising application in novel electrode material field of lithium-ion batteries.

Musical rhythm spectra from Bach to Joplin obey a 1/f power law.

PubMed

Levitin, Daniel J; Chordia, Parag; Menon, Vinod

2012-03-06

Much of our enjoyment of music comes from its balance of predictability and surprise. Musical pitch fluctuations follow a 1/f power law that precisely achieves this balance. Musical rhythms, especially those of Western classical music, are considered highly regular and predictable, and this predictability has been hypothesized to underlie rhythm's contribution to our enjoyment of music. Are musical rhythms indeed entirely predictable and how do they vary with genre and composer? To answer this question, we analyzed the rhythm spectra of 1,788 movements from 558 compositions of Western classical music. We found that an overwhelming majority of rhythms obeyed a 1/f(β) power law across 16 subgenres and 40 composers, with β ranging from ∼0.5-1. Notably, classical composers, whose compositions are known to exhibit nearly identical 1/f pitch spectra, demonstrated distinctive 1/f rhythm spectra: Beethoven's rhythms were among the most predictable, and Mozart's among the least. Our finding of the ubiquity of 1/f rhythm spectra in compositions spanning nearly four centuries demonstrates that, as with musical pitch, musical rhythms also exhibit a balance of predictability and surprise that could contribute in a fundamental way to our aesthetic experience of music. Although music compositions are intended to be performed, the fact that the notated rhythms follow a 1/f spectrum indicates that such structure is no mere artifact of performance or perception, but rather, exists within the written composition before the music is performed. Furthermore, composers systematically manipulate (consciously or otherwise) the predictability in 1/f rhythms to give their compositions unique identities.

From the Cover: Musical rhythm spectra from Bach to Joplin obey a 1/f power law

NASA Astrophysics Data System (ADS)

Levitin, Daniel J.; Chordia, Parag; Menon, Vinod

2012-03-01

Much of our enjoyment of music comes from its balance of predictability and surprise. Musical pitch fluctuations follow a 1/f power law that precisely achieves this balance. Musical rhythms, especially those of Western classical music, are considered highly regular and predictable, and this predictability has been hypothesized to underlie rhythm's contribution to our enjoyment of music. Are musical rhythms indeed entirely predictable and how do they vary with genre and composer? To answer this question, we analyzed the rhythm spectra of 1,788 movements from 558 compositions of Western classical music. We found that an overwhelming majority of rhythms obeyed a 1/fβ power law across 16 subgenres and 40 composers, with β ranging from ∼0.5-1. Notably, classical composers, whose compositions are known to exhibit nearly identical 1/f pitch spectra, demonstrated distinctive 1/f rhythm spectra: Beethoven's rhythms were among the most predictable, and Mozart's among the least. Our finding of the ubiquity of 1/f rhythm spectra in compositions spanning nearly four centuries demonstrates that, as with musical pitch, musical rhythms also exhibit a balance of predictability and surprise that could contribute in a fundamental way to our aesthetic experience of music. Although music compositions are intended to be performed, the fact that the notated rhythms follow a 1/f spectrum indicates that such structure is no mere artifact of performance or perception, but rather, exists within the written composition before the music is performed. Furthermore, composers systematically manipulate (consciously or otherwise) the predictability in 1/f rhythms to give their compositions unique identities.

Symposium on Massive Open Online Courses

ERIC Educational Resources Information Center

Krause, Steven D.; Rice, Jeff

2013-01-01

In this Symposium focused on MOOCs, this journal carries forward a tradition of attending to the technologies associated with composing and the teaching of composing. In the May 1983 issue of "College Composition and Communication," for example, most of the articles focus on composing and include a mix of inquiries, from Jack Selzer's on the…

Chapter 4. Cytomechanics of hair basics of the mechanical stability.

PubMed

Popescu, Crisan; Höcker, Hartwig

2009-01-01

Hair is a complex "cornified" multicellular tissue composed of cuticle and cortex cells mechanically acting as a whole. The cuticle cells overlap and cortex cells interdigitate, all cells being composed of different morphological elements and separated by the cell membrane complex (CMC). The CMC and the morphological elements of the cortex cells, the macrofibrils, composed of microfibrils or intermediate filaments (IFs), and the intermacrofibrillar and intermicrofibrillar cement or the amorphous matrix material determine the mechanical properties of hair. The IFs consist of alpha-keratin molecules being arranged in a sophisticated way of two parallel monomers and antiparallel and shifted dimers rationalized by the amino acid composition and sequence. The mechanical properties of hair result from mechanical interlocking effects, hydrophobic effects, hydrogen bridges, Coulombic interactions, and (covalent) isodipeptide and, in particular, disulfide bridges on a molecular level. The mechanical models applied to hair are based on a simple two-component system, the microfibril/matrix structure. An important regime of the stress-strain curve is the transition of the molecules of the microfibrils from the alpha-helical to the beta-sheet structure. Due to the longitudinal orientation of the IF molecules the longitudinal swelling of the fibers in water is negligible, the radial swelling, however, is substantial.

Osmium, tungsten, and chromium isotopes in sediments and in Ni-rich spinel at the K-T boundary: Signature of a chondritic impactor

NASA Astrophysics Data System (ADS)

Quitté, Ghylaine; Robin, Eric; Levasseur, Sylvain; Capmas, Françoise; Rocchia, Robert; Birck, Jean-Louis; Allègre, Claude Jean

It is now established that a large extraterrestrial object hit the Earth at the end of the Cretaceous period, about 65 Ma ago. We have investigated Re-Os, Hf-W, and Mn-Cr isotope systems in sediments from the Cretaceous and the Paleogene in order to characterize the type of impactor. Within the Cretaceous-Tertiary (K-T) boundary layer, extraterrestrial material is mixed with terrestrial material, causing a dilution of the extraterrestrial isotope signature that is difficult to quantify. A phase essentially composed of Ni-rich spinel, formed in the atmosphere mainly from melted projectile material, is likely to contain the extraterrestrial isotopic signature of the impactor. We show that the analysis of spinel is indeed the best approach to determine the initial isotope composition of the impactor, and that W and Cr isotopes confirm that the projectile was a carbonaceous chondrite.

Crystal and Magnetic Structures in Layered, Transition Metal Dihalides and Trihalides

DOE PAGES

McGuire, Michael A.

2017-04-27

Materials composed of two dimensional layers bonded to one another through weak van der Waals interactions often exhibit strongly anisotropic behaviors and can be cleaved into very thin specimens and sometimes into monolayer crystals. Interest in such materials is driven by the study of low dimensional physics and the design of functional heterostructures. Binary compounds with the compositions MX 2 and MX 3 where M is a metal cation and X is a halogen anion often form such structures. Magnetism can be incorporated by choosing a transition metal with a partially filled d-shell for M, enabling ferroic responses for enhancedmore » functionality. Here we give a brief overview of binary transition metal dihalides and trihalides, summarizing their crystallographic properties and long-range-ordered magnetic structures, focusing on those materials with layered crystal structures and partially filled d-shells required for combining low dimensionality and cleavability with magnetism.« less

Single-Step Reagentless Laser Scribing Fabrication of Electrochemical Paper-Based Analytical Devices.

PubMed

de Araujo, William R; Frasson, Carolina M R; Ameku, Wilson A; Silva, José R; Angnes, Lúcio; Paixão, Thiago R L C

2017-11-20

A single-step laser scribing process is used to pattern nanostructured electrodes on paper-based devices. The facile and low-cost technique eliminates the need for chemical reagents or controlled conditions. This process involves the use of a CO 2 laser to pyrolyze the surface of the paperboard, producing a conductive porous non-graphitizing carbon material composed of graphene sheets and composites with aluminosilicate nanoparticles. The new electrode material was extensively characterized, and it exhibits high conductivity and an enhanced active/geometric area ratio; it is thus well-suited for electrochemical purposes. As a proof-of-concept, the devices were successfully employed for different analytical applications in the clinical, pharmaceutical, food, and forensic fields. The scalable and green fabrication method associated with the features of the new material is highly promising for the development of portable electrochemical devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent results concerning the stability of viscoelastic shear deformable plates under compressive edge loading

NASA Technical Reports Server (NTRS)

Librescu, L.; Chandiramani, N. K.

1989-01-01

Some recent results obtained by the authors are summarized concerning the stability of transversely isotropic flat panels whose materials exhibit a viscoelastic behavior and whose edges are subjected to in-plane biaxial compressive loads. Two transversely isotropic type materials, largely used in advanced technology, are considered: (1) the pyrolytic-graphite type, used in the thermal protection of aerospace vehicles, and (2) the type corresponding to unidirectional fiber-reinforced composites. In the former case, the planes of isotropy are parallel at each point to the midplane of the plate. In the latter case, they are normal to the fiber directions. The micromechanical relations developed by Aboudi (1984, 1986, 1987) are considered in conjunction with the correspondence principle of linear viscoelastic theory in order to predict the macroscopic viscoelastic properties of a material composed of uniaxial elastic fibers embedded in a linear viscoelastic matrix.

High T c layered ferrielectric crystals by coherent spinodal decomposition

DOE PAGES

Susner, Michael A.; Belianinov, Alex; Borisevich, Albina Y.; ...

2015-11-13

Research in the rapidly-developing field of 2D-electronic materials has thus far been focused on metallic and semiconducting materials. However, complementary dielectric materials such as non-linear dielectrics are needed to enable realistic device architectures. Candidate materials require tunable dielectric properties and pathways for heterostructure assembly. Here we report on a family of cation-deficient transition metal thiophosphates whose unique chemistry makes them a viable prospect for these applications. In these materials, naturally occurring ferrielectric heterostructures composed of centrosymmetric In 4/3P 2S 6 and ferrielectrically-active CuInP 2S 6 are realized by controllable chemical phase separation in van-der-Waals bonded single crystals. CuInP 2S 6more » by itself is a layered ferrielectric with Tc just over room-temperature which rapidly decreases with homogenous doping. Surprisingly, in our composite materials, the ferrielectric Tc of the polar CuInP 2S 6 phase increases. This effect is enabled by unique spinodal decomposition that retains the overall van-der-Waals layered morphology of the crystal, but chemically separates CuInP 2S 6 and In 4/3P 2S 6 within each layer. The average spatial periodicity of the distinct chemical phases can be finely controlled by altering the composition and/or synthesis conditions. One intriguing prospect for such layered spinodal alloys is large volume synthesis of 2D in-plane heterostructures with periodically alternating polar and non-polar phases.« less

40 CFR 227.13 - Dredged materials.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Dredged material is composed predominantly of sand, gravel, rock, or any other naturally occurring bottom...) Dredged material is for beach nourishment or restoration and is composed predominantly of sand, gravel or... major constituents of the liquid phase are in compliance with the applicable marine water quality...

The use of polyimide-modified aluminum nitride fillers in AlN@PI/Epoxy composites with enhanced thermal conductivity for electronic encapsulation

PubMed Central

Zhou, Yongcun; Yao, Yagang; Chen, Chia-Yun; Moon, Kyoungsik; Wang, Hong; Wong, Ching-ping

2014-01-01

Polymer modified fillers in composites has attracted the attention of numerous researchers. These fillers are composed of core-shell structures that exhibit enhanced physical and chemical properties that are associated with shell surface control and encapsulated core materials. In this study, we have described an apt method to prepare polyimide (PI)-modified aluminum nitride (AlN) fillers, AlN@PI. These fillers are used for electronic encapsulation in high performance polymer composites. Compared with that of untreated AlN composite, these AlN@PI/epoxy composites exhibit better thermal and dielectric properties. At 40 wt% of filler loading, the highest thermal conductivity of AlN@PI/epoxy composite reached 2.03 W/mK. In this way, the thermal conductivity is approximately enhanced by 10.6 times than that of the used epoxy matrix. The experimental results exhibiting the thermal conductivity of AlN@PI/epoxy composites were in good agreement with the values calculated from the parallel conduction model. This research work describes an effective pathway that modifies the surface of fillers with polymer coating. Furthermore, this novel technique improves the thermal and dielectric properties of fillers and these can be used extensively for electronic packaging applications. PMID:24759082

Analytical design model for a piezo-composite unimorph actuator and its verification using lightweight piezo-composite curved actuators

NASA Astrophysics Data System (ADS)

Yoon, K. J.; Park, K. H.; Lee, S. K.; Goo, N. S.; Park, H. C.

2004-06-01

This paper describes an analytical design model for a layered piezo-composite unimorph actuator and its numerical and experimental verification using a LIPCA (lightweight piezo-composite curved actuator) that is lighter than other conventional piezo-composite type actuators. The LIPCA is composed of top fiber composite layers with high modulus and low CTE (coefficient of thermal expansion), a middle PZT ceramic wafer, and base layers with low modulus and high CTE. The advantages of the LIPCA design are to replace the heavy metal layer of THUNDER by lightweight fiber-reinforced plastic layers without compromising the generation of high force and large displacement and to have design flexibility by selecting the fiber direction and the number of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use a resin prepreg system. A piezo-actuation model for a laminate with piezo-electric material layers and fiber composite layers is proposed to predict the curvature and residual stress of the LIPCA. To predict the actuation displacement of the LIPCA with curvature, a finite element analysis method using the proposed piezo-actuation model is introduced. The predicted deformations are in good agreement with the experimental ones.

A statistical physics view of pitch fluctuations in the classical music from Bach to Chopin: evidence for scaling.

PubMed

Liu, Lu; Wei, Jianrong; Zhang, Huishu; Xin, Jianhong; Huang, Jiping

2013-01-01

Because classical music has greatly affected our life and culture in its long history, it has attracted extensive attention from researchers to understand laws behind it. Based on statistical physics, here we use a different method to investigate classical music, namely, by analyzing cumulative distribution functions (CDFs) and autocorrelation functions of pitch fluctuations in compositions. We analyze 1,876 compositions of five representative classical music composers across 164 years from Bach, to Mozart, to Beethoven, to Mendelsohn, and to Chopin. We report that the biggest pitch fluctuations of a composer gradually increase as time evolves from Bach time to Mendelsohn/Chopin time. In particular, for the compositions of a composer, the positive and negative tails of a CDF of pitch fluctuations are distributed not only in power laws (with the scale-free property), but also in symmetry (namely, the probability of a treble following a bass and that of a bass following a treble are basically the same for each composer). The power-law exponent decreases as time elapses. Further, we also calculate the autocorrelation function of the pitch fluctuation. The autocorrelation function shows a power-law distribution for each composer. Especially, the power-law exponents vary with the composers, indicating their different levels of long-range correlation of notes. This work not only suggests a way to understand and develop music from a viewpoint of statistical physics, but also enriches the realm of traditional statistical physics by analyzing music.

Materiaux composites supraconducteurs

NASA Astrophysics Data System (ADS)

Kerjouan, Philippe; Boterel, Florence; Lostec, Jean; Bertot, Jean-Paul; Haussonne, Jean-Marie

1991-11-01

The new superconductor materials with a high critical current own a large importance as well in the electronic components or in the electrotechnical devices fields. The deposit of such materials with the thick films technology is to be more and more developped in the years to come. Therefore, we tried to realize such thick films screen printed on alumina, and composed mainly of the YBa2CU3O{7-δ} material. We first realized a composite material glass/YBa2CU3O{7-δ}, by analogy with the classical screen-printed inks where the glass ensures the bonding with the substrate. We thus realized different materials by using some different classes of glass. These materials owned a superconducting transition close to the one of the pure YBa2CU3O{7-δ} material. We made a slurry with the most significant composite materials and binders, and screen-printed them on an alumina substrate preliminary or not coated with a diffusion barrier layer. After firing, we studied the thick films adhesion, the alumina/glass/composite material interfaces, and their superconducting properties. Les nouveaux matériaux supraconducteurs à haute température critique ont potentiellement un rôle important à jouer dans le domaine de l'électronique et de l'électrotechnique. En particulier, le dépôt d'oxydes supraconducteurs sur divers types de substrats est une technologie amenée à se développer. Nous avons donc entrepris une étude dont l'objet est la réalisation de conducteurs sérigraphiés sur alumine et composés essentiellement du matériau YBa2CU3O{7-δ}. Nous avons tout d'abord cherché à réaliser un composite verre/YBa2CU3O{7-δ}, par analogie au principe de réalisation de couches conductrices sérigraphiées, le verre permettant d'obtenir une liaison physico-chimique avec le substrat. Une étude préliminaire a permis de réaliser divers matériaux composites massifs, utilisant différentes familles de verres. Ces matériaux massifs, se présentant sous la forme de barreaux de 2 × 2 mm de section, étaient supraconducteurs à une température pouvant être voisine de celle du matériau YBa2CU3O{7-δ} initial. Nous avons mis les plus significatifs de ces matériaux composites en suspension dans un liant organique nous permettant de les déposer en couches épaisses sur des substrats d'alumine recouverts ou non d'une première couche de verre. Nous avons étudié après cuisson l'adhérence des dépôts, les interfaces alumine/verre/composite, ainsi que les propriétés supraconductrices.

Lightweight bladder lined pressure vessels

DOEpatents

Mitlitsky, Fred; Myers, Blake; Magnotta, Frank

1998-01-01

A lightweight, low permeability liner for graphite epoxy composite compressed gas storage vessels. The liner is composed of polymers that may or may not be coated with a thin layer of a low permeability material, such as silver, gold, or aluminum, deposited on a thin polymeric layer or substrate which is formed into a closed bladder using torispherical or near torispherical end caps, with or without bosses therein, about which a high strength to weight material, such as graphite epoxy composite shell, is formed to withstand the storage pressure forces. The polymeric substrate may be laminated on one or both sides with additional layers of polymeric film. The liner may be formed to a desired configuration using a dissolvable mandrel or by inflation techniques and the edges of the film seamed by heat sealing. The liner may be utilized in most any type of gas storage system, and is particularly applicable for hydrogen, gas mixtures, and oxygen used for vehicles, fuel cells or regenerative fuel cell applications, high altitude solar powered aircraft, hybrid energy storage/propulsion systems, and lunar/Mars space applications, and other applications requiring high cycle life.

Method for forming a bladder for fluid storage vessels

DOEpatents

Mitlitsky, Fred; Myers, Blake; Magnotta, Frank

2000-01-01

A lightweight, low permeability liner for graphite epoxy composite compressed gas storage vessels. The liner is composed of polymers that may or may not be coated with a thin layer of a low permeability material, such as silver, gold, or aluminum, deposited on a thin polymeric layer or substrate which is formed into a closed bladder using torispherical or near torispherical end caps, with or without bosses therein, about which a high strength to weight material, such as graphite epoxy composite shell, is formed to withstand the storage pressure forces. The polymeric substrate may be laminated on one or both sides with additional layers of polymeric film. The liner may be formed to a desired configuration using a dissolvable mandrel or by inflation techniques and the edges of the film seamed by heat sealing. The liner may be utilized in most any type of gas storage system, and is particularly applicable for hydrogen, gas mixtures, and oxygen used for vehicles, fuel cells or regenerative fuel cell applications, high altitude solar powered aircraft, hybrid energy storage/propulsion systems, and lunar/Mars space applications, and other applications requiring high cycle life.

The design of a Li-ion full cell battery using a nano silicon and nano multi-layer graphene composite anode

NASA Astrophysics Data System (ADS)

Eom, KwangSup; Joshi, Tapesh; Bordes, Arnaud; Do, Inhwan; Fuller, Thomas F.

2014-03-01

In this study, a Si-graphene composite, which is composed of nano Si particles and nano-sized multi-layer graphene particles, and micro-sized multi-layer graphene plate conductor, was used as the anode for Li-ion battery. The Si-graphene electrode showed the high capacity and stable cyclability at charge/discharge rate of C/2 in half cell tests. Nickel cobalt aluminum material (NCA) was used as a cathode in the full cell to evaluate the practicality of the new Si-graphene material. Although the Si-graphene anode has more capacity than the NCA cathode in this designed full cell, the Si-graphene anode had a greater effect on the full-cell performance due to its large initial irreversible capacity loss and continuous SEI formation during cycling. When fluoro-ethylene carbonate was added to the electrolyte, the cyclability of the full cell was much improved due to less SEI formation, which was confirmed by the decreases in the 1st irreversible capacity loss, overpotential for the 1st lithiation, and the resistance of the SEI.

Optically Tunable Chiral Plasmonic Guest-Host Cellulose Films Weaved with Long-range Ordered Silver Nanowires.

PubMed

Chu, Guang; Wang, Xuesi; Chen, Tianrui; Gao, Jianxiong; Gai, Fangyuan; Wang, Yu; Xu, Yan

2015-06-10

Plasmonic materials with large chiroptical activity at visible wavelength have attracted considerable attention due to their potential applications in metamaterials. Here we demonstrate a novel guest-host chiral nematic liquid crystal film composed of bulk self-co-assembly of the dispersed plasmonic silver nanowires (AgNWs) and cellulose nanocrystals (CNCs). The AgNWs-CNCs composite films show strong plasmonic optical activities, that are dependent on the chiral photonic properties of the CNCs host medium and orientation of the guest AgNWs. Tunable chiral distribution of the aligned anisotropic AgNWs with long-range order is obtained through the CNCs liquid crystal mediated realignment. The chiral plasmonic optical activity of the AgNWs-CNCs composite films can be tuned by changing the interparticle electrostatic repulsion between the CNCs nanorods and AgNWs. We also observe an electromagnetic energy transfer phenomena among the plasmonic bands of AgNWs, due to the modulation of the photonic band gap of the CNCs host matrix. This facile approach for fabricating chiral macrostructured plasmonic materials with optically tunable property is of interest for a variety of advanced optics applications.

Engineering and environmental properties of thermally treated mixtures containing MSWI fly ash and low-cost additives.

PubMed

Polettini, A; Pomi, R; Trinci, L; Muntoni, A; Lo Mastro, S

2004-09-01

An experimental work was carried out to investigate the feasibility of application of a sintering process to mixtures composed of Municipal Solid Waste Incinerator (MSWI) fly ash and low-cost additives (waste from feldspar production and cullet). The proportions of the three constituents were varied to adjust the mixture compositions to within the optimal range for sintering. The material was compacted in cylindrical specimens and treated at 1100 and 1150 degrees C for 30 and 60 min. Engineering and environmental characteristics including weight loss, dimensional changes, density, open porosity, mechanical strength, chemical stability and leaching behavior were determined for the treated material, allowing the relationship between the degree of sintering and both mixture composition and treatment conditions to be singled out. Mineralogical analyses detected the presence of neo-formation minerals from the pyroxene group. Estimation of the extent of metal loss from the samples indicated that the potential for volatilization of species of Pb, Cd and Zn is still a matter of major concern when dealing with thermal treatment of incinerator ash.

Tektites in cretaceous-tertiary boundary rocks on Haiti and their bearing on the Alvarez impact extinction hypothesis

NASA Astrophysics Data System (ADS)

Izett, G. A.

1991-11-01

Observational and geochemical data for glass objects recently discovered, by Izett et al. (1990), in K-T boundary rocks on the island of Haiti are presented. The presence of tektites, which are of terrestrial impact origin, in the same bed with a Pt-metal abundance anomaly and shocked mineral grains enormously strengthens the impact component of the Alvarez K-T impact extinction hypothesis. Shocked quartz grains in samples of the Haitian K-T boundary marker bed are about the same size as those at the K-T boundary sites in western North America. Petrographic observations indicate that the K-T marker bed on Haiti is not a primary air fall unit composed entirely of impact ejecta. It contains a small volcanogenic component of locally derived material admixed with the impact ejecta during deposition on the seafloor. The major and trace element composition of the Haitian tektites, in particular, the high Rb and REE content, suggests that the target material melted during the K-T impact was sedimentary with an average composition of andesite, not mafic or ultramafic oceanic crust.

Lithium sulfide compositions for battery electrolyte and battery electrode coatings

DOEpatents

Liang, Chengdu; Liu, Zengcai; Fu, Wunjun; Lin, Zhan; Dudney, Nancy J; Howe, Jane Y; Rondinone, Adam J

2013-12-03

Methods of forming lithium-containing electrolytes are provided using wet chemical synthesis. In some examples, the lithium containing electroytes are composed of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7. The solid electrolyte may be a core shell material. In one embodiment, the core shell material includes a core of lithium sulfide (Li.sub.2S), a first shell of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7, and a second shell including one or .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7 and carbon. The lithium containing electrolytes may be incorporated into wet cell batteries or solid state batteries.

Lithium sulfide compositions for battery electrolyte and battery electrode coatings

DOEpatents

Liang, Chengdu; Liu, Zengcai; Fu, Wujun; Lin, Zhan; Dudney, Nancy J; Howe, Jane Y; Rondinone, Adam J

2014-10-28

Method of forming lithium-containing electrolytes are provided using wet chemical synthesis. In some examples, the lithium containing electrolytes are composed of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7. The solid electrolyte may be a core shell material. In one embodiment, the core shell material includes a core of lithium sulfide (Li.sub.2S), a first shell of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7, and a second shell including one of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7 and carbon. The lithium containing electrolytes may be incorporated into wet cell batteries or solid state batteries.

Iron abundance in the moon from magnetometer measurements

NASA Technical Reports Server (NTRS)

Parkin, C. W.; Dyal, P.; Daily, W. D.

1973-01-01

Apollo 12 and 15 lunar surface magnetometer data with simultaneous lunar orbiting Explorer 35 data are used to plot hysteresis curves for the whole moon. From these curves a whole-moon permeability mu = 1.029 + 0.024 or - 0.019 is calculated. This result implies that the moon is not composed entirely of paramagnetic material, but that ferromagnetic material such as free iron exists in sufficient amounts to dominate the bulk lunar susceptibility. From the magnetic data the ferromagnetic free iron abundance is calculated. Then for assumed compositional models of the moon the additional paramagnetic iron is determined, yielding total lunar iron content. The calculated abundances are as follows: ferromagnetic free iron = 5 + or - 4 wt. percent, and total iron in the moon = 9 + or - 4 wt. percent.

Iron abundance in the moon from magnetometer measurements

NASA Technical Reports Server (NTRS)

Parkin, C. W.; Dyal, P.; Daily, W. D.

1973-01-01

Apollo 12 and 15 lunar surface magnetometer data with simultaneous lunar orbiting Explorer 35 data are used to plot hysteresis curves for the whole moon. From these curves a whole-moon permeability of 1.029 (+0.024 or -0.019) is calculated. This result implies that the moon is not composed entirely of paramagnetic material, but that ferromagnetic material such as free iron exists in sufficient amounts to dominate the bulk lunar susceptibility. From the magnetic data the ferromagnetic free iron abundance is calculated. Then for assumed compositional models of the moon the additional paramagnetic iron is determined, yielding total lunar iron content. The calculated abundances are as follows: ferromagnetic free iron, 5 plus or minus 4 wt %; total iron in the moon, 9 plus or minus 4 wt %.

Method of making a layered composite electrode/electrolyte

DOEpatents

Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

2005-01-25

An electrode/electrolyte structure is prepared by a plurality of methods. An unsintered (possibly bisque fired) moderately catalytic electronically-conductive or homogeneous mixed ionic electronic conductive electrode material is deposited on a layer composed of a sintered or unsintered ionically-conductive electrolyte material prior to being sintered. A layer of particulate electrode material is deposited on an unsintered ("green") layer of electrolyte material and the electrode and electrolyte layers are sintered simultaneously, sometimes referred to as "co-firing," under conditions suitable to fully densify the electrolyte while the electrode retains porosity. Or, the layer of particulate electrode material is deposited on a previously sintered layer of electrolyte, and then sintered. Subsequently, a catalytic material is added to the electrode structure by infiltration of an electrolcatalyst precursor (e.g., a metal salt such as a transition metal nitrate). This may be followed by low temperature firing to convert the precursor to catalyst. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in an ionic (electrochemical) device such as fuel cells and electrolytic gas separation systems.

Carbon Nanotube Membranes: Synthesis, Properties, and Future Filtration Applications

PubMed Central

Rashid, Md. Harun-Or; Ralph, Stephen F.

2017-01-01

Over the course of the past decade, there has been growing interest in the development of different types of membranes composed of carbon nanotubes (CNTs), including buckypapers and composite materials, for an ever-widening range of filtration applications. This article provides an overview of how different types of CNT membranes are prepared and the results obtained from investigations into their suitability for different applications. The latter involve the removal of small particles from air samples, the filtration of aqueous solutions containing organic compounds and/or bacteria, and the separation of individual liquids present in mixtures. A growing number of reports have demonstrated that the incorporation of CNTs into composite membranes confers an improved resistance to fouling caused by biomacromolecules and bacteria. These results are discussed, along with evidence that demonstrates it is possible to further reduce fouling by taking advantage of the inherent conductivity of composite membranes containing CNTs, as well as by using different types of electrochemical stimuli. PMID:28468314

Wood-Graphene Oxide Composite for Highly Efficient Solar Steam Generation and Desalination.

PubMed

Liu, Keng-Ku; Jiang, Qisheng; Tadepalli, Sirimuvva; Raliya, Ramesh; Biswas, Pratim; Naik, Rajesh R; Singamaneni, Srikanth

2017-03-01

Solar steam generation is a highly promising technology for harvesting solar energy, desalination and water purification. We introduce a novel bilayered structure composed of wood and graphene oxide (GO) for highly efficient solar steam generation. The GO layer deposited on the microporous wood provides broad optical absorption and high photothermal conversion resulting in rapid increase in the temperature at the liquid surface. On the other hand, wood serves as a thermal insulator to confine the photothermal heat to the evaporative surface and to facilitate the efficient transport of water from the bulk to the photothermally active space. Owing to the tailored bilayer structure and the optimal thermo-optical properties of the individual components, the wood-GO composite structure exhibited a solar thermal efficiency of ∼83% under simulated solar excitation at a power density of 12 kW/m 2 . The novel composite structure demonstrated here is highly scalable and cost-efficient, making it an attractive material for various applications involving large light absorption, photothermal conversion and heat localization.

Evidence for a Single Ureilite Parent Asteroid from a Petrologic Study of Polymict Ureilites

NASA Technical Reports Server (NTRS)

Downes, Hilary; Mittlefehldt, David W.

2006-01-01

Ureilites are ultramafic achondrites composed of olivine and pyroxene, with minor elemental C, mostly as graphite [1]. The silicate composition indicates loss of a basaltic component through igneous processing, yet the suite is very heterogeneous in O isotopic composition inherited from nebular processes [2]. Because of this, it has not yet been established whether ureilites were derived from a single parent asteroid or from multiple parents. Most researchers tacitly assume a single parent asteroid, but the wide variation in mineral and oxygen isotope compositions could be readily explained by an origin in multiple parent asteroids that had experienced a similar evolution. Numerous ureilite meteorites have been found in Antarctica, among them several that are clearly paired (Fig. 1) and two that are strongly brecciated (EET 83309, EET 87720). We have begun a detailed petrologic study of these latter two samples in order to characterize the range of materials in them. One goal is to attempt to determine whether ureilites were derived from a single parent asteroid.

The human gut microbiota and virome: Potential therapeutic implications.

PubMed

Scarpellini, Emidio; Ianiro, Gianluca; Attili, Fabia; Bassanelli, Chiara; De Santis, Adriano; Gasbarrini, Antonio

2015-12-01

Human gut microbiota is a complex ecosystem with several functions integrated in the host organism (metabolic, immune, nutrients absorption, etc.). Human microbiota is composed by bacteria, yeasts, fungi and, last but not least, viruses, whose composition has not been completely described. According to previous evidence on pathogenic viruses, the human gut harbours plant-derived viruses, giant viruses and, only recently, abundant bacteriophages. New metagenomic methods have allowed to reconstitute entire viral genomes from the genetic material spread in the human gut, opening new perspectives on the understanding of the gut virome composition, the importance of gut microbiome, and potential clinical applications. This review reports the latest evidence on human gut "virome" composition and its function, possible future therapeutic applications in human health in the context of the gut microbiota, and attempts to clarify the role of the gut "virome" in the larger microbial ecosystem. Copyright © 2015 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Ag-Cu mixed phase plasmonic nanostructures fabricated by shadow nanosphere lithography and glancing angle co-deposition

NASA Astrophysics Data System (ADS)

Ingram, Whitney; Larson, Steven; Carlson, Daniel; Zhao, Yiping

2017-01-01

By combining shadow nanosphere lithography with a glancing angle co-deposition technique, mixed-phase Ag-Cu triangular nanopatterns and films were fabricated. They were prepared at different compositions with respect to Ag from 100% to 0% by changing the relative deposition ratio of each metal. Characterizations by ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffraction revealed that the thin films and nanopatterns were composed of small, well-mixed Ag and Cu nano-grains with a diameter less than 20 nm, and their optical properties could be described by an effective medium theory. All compositions of the nanopattern had the same shape, but showed tunable localized surface plasmon resonance (LSPR) properties. In general, the LSPR of the nanopatterns redshifted with decreasing composition. Such a relation could be fitted by an empirical model based on the bulk theory of alloy plasmonics. By changing the colloidal template and the material deposited, this fabrication technique can be used to produce other alloy plasmonic nanostructures with predicted LSPR wavelengths.

Ag-Cu mixed phase plasmonic nanostructures fabricated by shadow nanosphere lithography and glancing angle co-deposition.

PubMed

Ingram, Whitney; Larson, Steven; Carlson, Daniel; Zhao, Yiping

2017-01-06

By combining shadow nanosphere lithography with a glancing angle co-deposition technique, mixed-phase Ag-Cu triangular nanopatterns and films were fabricated. They were prepared at different compositions with respect to Ag from 100% to 0% by changing the relative deposition ratio of each metal. Characterizations by ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffraction revealed that the thin films and nanopatterns were composed of small, well-mixed Ag and Cu nano-grains with a diameter less than 20 nm, and their optical properties could be described by an effective medium theory. All compositions of the nanopattern had the same shape, but showed tunable localized surface plasmon resonance (LSPR) properties. In general, the LSPR of the nanopatterns redshifted with decreasing composition. Such a relation could be fitted by an empirical model based on the bulk theory of alloy plasmonics. By changing the colloidal template and the material deposited, this fabrication technique can be used to produce other alloy plasmonic nanostructures with predicted LSPR wavelengths.

Analytical and numerical solutions for mass diffusion in a composite cylindrical body

NASA Astrophysics Data System (ADS)

Kumar, A.

1980-12-01

The analytical and numerical solution techniques were investigated to study moisture diffusion problems in cylindrical bodies that are assumed to be composed of a finite number of layers of different materials. A generalized diffusion model for an n-layer cylindrical body with discontinuous moisture content at the interfaces was developed and the formal solutions were obtained. The model is to be used for describing mass transfer rates of any composite body, such as an ear of corn which could be assumed of consisting two different layers: the inner core represents the woody cob and the outer cylinder represents the kernel layer. Data describing the fully exposed drying characteristics of ear corn at high air velocity were obtained under different drying conditions. Ear corns were modeled as homogeneous bodies since composite model did not improve the fit substantially. A computer program using multidimensional optimization technique showed that diffusivity was an exponential function of moisture content and an arrhenius function of temperature of drying air.

Antifogging and icing-delay properties of composite micro- and nanostructured surfaces.

PubMed

Wen, Mengxi; Wang, Lei; Zhang, Mingqian; Jiang, Lei; Zheng, Yongmei

2014-03-26

A composite micro/nanostrucutred (MN) surface was designed using poly(vinylidene difluoride) (PVDF) polymer in combination with ZnO materials via heat-pattern-transfer and crystal-growth techniques. The surface, composed of ZnO nanohairs over PVDF microratchets (i.e., ZP-MN), displays excellent antifogging and icing-delay properties. Condensed water droplets can be easily shed from the ZP-MN surface at -5 °C for ∼1600 s via a slight wind or tilting. The droplets do not completely freeze on the ZP-MN surface at -10 °C until ∼7360 s. This investigation offers a way to design a structured surface that possesses anti-icing ability, which is significant because it can be extended to fields such as microdevices, engineering systems, and engines that operate in a cold or humid environment.

Dependence of Mechanical and Thermal Properties of Thermoplastic Composites on Electron Beam Irradiation

NASA Astrophysics Data System (ADS)

Kim, Sok Won; Park, K.; Lee, S. H.; Kang, J. S.; Kang, K. H.

2007-06-01

Since the restrictions for environmental protection being strengthened, thermoplastics reinforced with natural fibers (NF’s), such as jute, kenaf, flax, etc. have appeared as alternatives to chemical plastics for automobile interior materials. In this study, the thermal conductivity, tensile strength, and deformation of several kinds of thermoplastic composites composed of 50% polypropylene (PP) and 50% natural fiber (NF) irradiated by an electron beam (energy: 0.5 MeV, dose: 0 20 kGy) were measured. The length and thickness of PP and NF are 80 ± 10 mm and 40 120 μm, respectively. The results show that the thermal conductivity and the tensile strength changed and became minimum, when the dose of the electron beam was 10 kGy. However, the effect of the dose on the deformation was not clear.

[Study on the traditional lime mortar from the memorial archway in the southern Anhui province].

PubMed

Wei, Guo-Feng; Sun, Sheng; Wang, Cheng-Xing; Zhang, Bing-Jian; Chen, Xi-Min

2013-07-01

The traditional lime mortar was investigated by means of scanning electron microscope (SEM), X-ray diffractometry and Fourier transform infrared spectrometry (FTIR). The results show that the mortar from the memorial archway in the southern Anhui province was the organic-inorganic composite materials composed of lime with tung oil or sticky rice. It was found that the excellent performance of the tung oil-lime mortar can be explained by the compact lamellar organic-inorganic composite structure that was produced by carbonization reaction of lime, cross-linking reactions of tung oil and oxygen and complexing reaction of Ca2+ and -COO-. The compact micro-structure of sticky rice-lime mortar, which was produced due to carbonation process of lime controlled by amylopectin, should be the cause of the good performance of this kind of organic-inorganic mortar.

Compositional layering within the large low shear-wave velocity provinces (LLSVPs) in the lower mantle

NASA Astrophysics Data System (ADS)

Ballmer, Maxim; Lekic, Vedran; Schumacher, Lina; Ito, Garrett; Thomas, Christine

2016-04-01

Seismic tomography reveals two antipodal LLSVPs in the Earth's mantle, each extending from the core-mantle boundary (CMB) up to ~1000 km depth. The LLSVPs are thought to host primordial mantle materials that bear witness of early-Earth processes, and/or subducted basalt that has accumulated in the mantle over billions of years. A compositional distinction between the LLSVPs and the ambient mantle is supported by anti-correlation of bulk-sound and shear-wave velocity (Vs) anomalies as well as abrupt lateral gradients in Vs along LLSVP margins. Both of these observations, however, are mainly restricted to the LLSVP bottom domains (2300~2900 km depth), or hereinafter referred to as "deep distinct domains" (DDD). Seismic sensitivity calculations suggest that DDDs are more likely to be composed of primordial mantle material than of basaltic material. On the other hand, the seismic signature of LLSVP shallow domains (1000~2300 km depth) is consistent with a basaltic composition, though a purely thermal origin cannot be ruled out. Here, we explore the dynamical, seismological, and geochemical implications of the hypothesis that the LLSVPs are compositionally layered with a primordial bottom domain (or DDD) and a basaltic shallow domain. We test this hypothesis using 2D thermochemical mantle-convection models. Depending on the density difference between primordial and basaltic materials, the materials either mix or remain separate as they join to form thermochemical piles in the deep mantle. Separation of both materials within these piles provides an explanation for LLSVP seismic properties, including substantial internal vertical gradients in Vs observed at 400-700 km height above the CMB, as well as out-of-plane reflections on LLSVP sides over a range of depths. Predicted geometry of thermochemical piles is compared to LLSVP and DDD shapes as constrained by seismic cluster analysis. Geodynamic models predict short-lived "secondary" plumelets to rise from LLSVP roofs and to entrain basaltic material that has evolved in the lower mantle. Long-lived "primary" plumes rise from LLSVP margins and entrain a mix of materials, including small fractions of primordial mantle material. These predictions address the geochemical and geochronological record of intraplate hotspot volcanism on the Pacific plate. In general, the parameter range spanned by models that are able to reconcile observations provides a constraint for the intrinsic density anomaly (or composition) of DDDs. We use this constraint to evaluate a possible origin of DDDs from (basal) magma ocean cumulates. The study of LLSVP compositional layering has indeed important implications for our understanding of heat and material fluxes through mantle reservoirs, as well as bulk Earth chemistry and evolution.

Fabricating Superhydrophobic Polymeric Materials for Biomedical Applications

PubMed Central

Kaplan, Jonah; Grinstaff, Mark

2015-01-01

Superhydrophobic materials, with surfaces possessing permanent or metastable non-wetted states, are of interest for a number of biomedical and industrial applications. Here we describe how electrospinning or electrospraying a polymer mixture containing a biodegradable, biocompatible aliphatic polyester (e.g., polycaprolactone and poly(lactide-co-glycolide)), as the major component, doped with a hydrophobic copolymer composed of the polyester and a stearate-modified poly(glycerol carbonate) affords a superhydrophobic biomaterial. The fabrication techniques of electrospinning or electrospraying provide the enhanced surface roughness and porosity on and within the fibers or the particles, respectively. The use of a low surface energy copolymer dopant that blends with the polyester and can be stably electrospun or electrosprayed affords these superhydrophobic materials. Important parameters such as fiber size, copolymer dopant composition and/or concentration, and their effects on wettability are discussed. This combination of polymer chemistry and process engineering affords a versatile approach to develop application-specific materials using scalable techniques, which are likely generalizable to a wider class of polymers for a variety of applications. PMID:26383018

Application of Laser Based Ultrasound for NDE of Damage in Thick Stitched Composites

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Friedman, Adam D.; Hinders, Mark K.; Madaras, Eric I.

1997-01-01

As design engineers implement new composite systems such as thick, load bearing composite structures, they must have certifiable confidence in structure s durability and worthiness. This confidence builds from understanding the structural response and failure characteristics of simple components loaded in testing machines to tests on full scale sections. Nondestructive evaluation is an important element which can provide quantitative information on the damage initiation, propagation, and final failure modes for the composite structural components. Although ultrasound is generally accepted as a test method, the use of conventional ultrasound for in-situ monitoring of damage during tests of large structures is not practical. The use of lasers to both generate and detect ultrasound extends the application of ultrasound to in- situ sensing of damage in a deformed structure remotely and in a non-contact manner. The goal of the present research is to utilize this technology to monitor damage progression during testing. The present paper describes the application of laser based ultrasound to quantify damage in thick stitched composite structural elements to demonstrate the method. This method involves using a Q-switched laser to generate a rapid, local linear thermal strain on the surface of the structure. This local strain causes the generation of ultrasonic waves into the material. A second laser used with a Fabry-Perot interferometer detects the surface deflections. The use of fiber optics provides for eye safety and a convenient method of delivering the laser over long distances to the specimens. The material for these structural elements is composed of several stacks of composite material assembled together by stitching through the laminate thickness that ranging from 0.5 to 0.8 inches. The specimens used for these nondestructive evaluation studies had either impact damage or skin/stiffener interlaminar failure. Although little or no visible surface damage existed, internal damage was detected by laser based ultrasound.

Research-to-Resource: Programming Ensemble Literature Composed by Women

ERIC Educational Resources Information Center

Baker, Vicki; Biggers, Carter

2018-01-01

Research has indicated that a gender imbalance exists in the field of music composition. This inequitable distribution is clearly demonstrated in a state-mandated repertoire list in which women represent 3% of the wind band composers and 12% of the choral composers (all voicings). Ensemble directors are in a position to affect a change by…

Effects of composition of grains of debris flow on its impact force

NASA Astrophysics Data System (ADS)

Tang, jinbo; Hu, Kaiheng; Cui, Peng

2017-04-01

Debris flows compose of solid material with broad size distribution from fine sand to boulders. Impact force imposed by debris flows is a very important issue for protection engineering design and strongly influenced by their grain composition. However, this issue has not been studied in depth and the effects of grain composition not been considered in the calculation of the impact force. In this present study, the small-scale flume experiments with five kinds of compositions of grains for debris flow were carried out to study the effect of the composition of grains of debris flow on its impact force. The results show that the impact force of debris flow increases with the grain size, the hydrodynamic pressure of debris flow is calibrated based on the normalization parameter dmax/d50, in which dmax is the maximum size and d50 is the median size. Furthermore, a log-logistic statistic distribution could be used to describe the distribution of magnitude of impact force of debris flow, where the mean and the variance of the present distribution increase with grain size. This distribution proposed in the present study could be used to the reliability analysis of structures impacted by debris flow.

Preparation and Wear Resistance of Aluminum Composites Reinforced with In Situ Formed TiO/Al2O3

NASA Astrophysics Data System (ADS)

Qin, Q. D.; Huang, B. W.; Li, W.; Zeng, Z. Y.

2016-05-01

An in situ TiO/Al2O3-reinforced Al composite is successfully prepared using a powder metallurgy route by the reaction of Ti2CO and Al powder. The Ti2CO powder is produced by carrying out a carbothermic reduction of titanium dioxide at 1000 °C. XRD results show that the final product is composed of Al, TiO, Al2O3, and Al3Ti. Morphology examination of the composite reveals the presence of bigger blocks of TiO and fine particles of Al2O3 and the volume fraction of reinforcement is found to range between 18 and 55%. As the volume fraction of the reinforced materials approaches 50%, the particles start to agglomerate. Dry sliding wear tests conducted using a conventional pin-on-disk testing machine show that the wear resistance of the composite is higher than that of the pure aluminum ingot. The wear rate of the composite increases almost linearly with the increase in the wear distance. The sliding wear test shows that as the volume fraction of the reinforced phase increases, the coefficient of friction decreases. The wear mechanism is also discussed.

Oxidation and protection of fiberglass-epoxy composite masts for photovoltaic arrays in the low Earth orbital environment

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.; Paulsen, Phillip E.; Brady, Joyce A.; Ciancone, Michael L.

1988-01-01

Fiberglass-epoxy composites are considered for use as structural members for the mast of the space station solar array panel. The low Earth orbital environment in which space station is to operate is composed mainly of atomic oxygen, which has been shown to cause erosion of many organic materials and some metals. Ground based testing in a plasma asher was performed to determine the extent of degradation of fiberglass-epoxy composites when exposed to a simulated atomic oxygen environment. During exposure, the epoxy at the surface of the composite was oxidized, exposing individual glass fibers which could easily be removed. Several methods of protecting the composite were evaluated in an atomic oxygen environment and with thermal cycling and flexing. The protection techniques evaluated to date include an aluminum braid covering, an indium-tin eutectic and a silicone based paint. The open aluminum braid offered little protection while the CV-1144 coating offered some initial protection against atomic oxygen, but appears to develop cracks which accelerate degradation when flexed. Coatings such as the In-Sn eutectic may provide adequate protection by containing the glass fibers even though mass loss still occurs.

New Approach to Ultrasonic Spectroscopy Applied to Flywheel Rotors

NASA Technical Reports Server (NTRS)

Harmon, Laura M.; Baaklini, George Y.

2002-01-01

Flywheel energy storage devices comprising multilayered composite rotor systems are being studied extensively for use in the International Space Station. A flywheel system includes the components necessary to store and discharge energy in a rotating mass. The rotor is the complete rotating assembly portion of the flywheel, which is composed primarily of a metallic hub and a composite rim. The rim may contain several concentric composite rings. This article summarizes current ultrasonic spectroscopy research of such composite rings and rims and a flat coupon, which was manufactured to mimic the manufacturing of the rings. Ultrasonic spectroscopy is a nondestructive evaluation (NDE) method for material characterization and defect detection. In the past, a wide bandwidth frequency spectrum created from a narrow ultrasonic signal was analyzed for amplitude and frequency changes. Tucker developed and patented a new approach to ultrasonic spectroscopy. The ultrasonic system employs a continuous swept-sine waveform and performs a fast Fourier transform on the frequency spectrum to create the spectrum resonance spacing domain, or fundamental resonant frequency. Ultrasonic responses from composite flywheel components were analyzed at Glenn to assess this NDE technique for the quality assurance of flywheel applications.

Stretchable conductors by kirigami patterning of aramid-silver nanocomposites with zero conductance gradient

NASA Astrophysics Data System (ADS)

Lyu, Jing; Hammig, Mark D.; Liu, Lehao; Xu, Lizhi; Chi, Hang; Uher, Ctirad; Li, Tiehu; Kotov, Nicholas A.

2017-10-01

Materials that are both stretchable and electrically conductive enable a broad spectrum of applications in sensing, actuating, electronics, optics and energy storage. The materials engineering concept of stretchable conductors is primarily based on combining nanowires, nanoribbons, nanoparticles, or nanocarbons with rubbery polymers to obtain composites with different abilities to transport charge and alter their nanoscale organization under strain. Although some of these composites reveal remarkably interesting multiscale reconfigurability and self-assembly phenomena, decreasing conductance with increased strain has restricted their widespread implementation. In a broader physical sense, the dependence of conductance on stress is undesirable because it requires a correlated change of electrical inputs. In this paper, we describe highly conductive and deformable sheets with a conductivity as high as 230 000 S cm-1, composed of silver nanoparticles, infiltrated within a porous aramid nanofiber (ANF) matrix. By forming a kirigami pattern, consisting of a regularized network of notches cut within the films, their ultimate tensile strain is improved from ˜2% to beyond 100%. The use of ANFs derived from well-known ultrastrong Kevlar™ fibers imparts high mechanical performance to the base composite. Importantly, the conductance of the films remains constant, even under large deformation resulting in a material with a zero conductance gradient. Unlike other nanocomposites for which strain and conductance are strongly coupled, the kirigami nanocomposite provides a pathway to demanding applications for flexible and stretchable electronics with power/voltage being unaffected by the deformation mode and temperature.

3D printing PLGA: a quantitative examination of the effects of polymer composition and printing parameters on print resolution

PubMed Central

Guo, Ting; Holzberg, Timothy R; Lim, Casey G; Gao, Feng; Gargava, Ankit; Trachtenberg, Jordan E; Mikos, Antonios G; Fisher, John P

2018-01-01

In the past few decades, 3D printing has played a significant role in fabricating scaffolds with consistent, complex structure that meet patient-specific needs in future clinical applications. Although many studies have contributed to this emerging field of additive manufacturing, which includes material development and computer-aided scaffold design, current quantitative analyses do not correlate material properties, printing parameters, and printing outcomes to a great extent. A model that correlates these properties has tremendous potential to standardize 3D printing for tissue engineering and biomaterial science. In this study, we printed poly(lactic-co-glycolic acid) (PLGA) utilizing a direct melt extrusion technique without additional ingredients. We investigated PLGA with various lactic acid: glycolic acid (LA:GA) molecular weight ratios and end caps to demonstrate the dependence of the extrusion process on the polymer composition. Micro-computed tomography was then used to evaluate printed scaffolds containing different LA:GA ratios, composed of different fiber patterns, and processed under different printing conditions. We built a statistical model to reveal the correlation and predominant factors that determine printing precision. Our model showed a strong linear relationship between the actual and predicted precision under different combinations of printing conditions and material compositions. This quantitative examination establishes a significant foreground to 3D print biomaterials following a systematic fabrication procedure. Additionally, our proposed statistical models can be applied to couple specific biomaterials and 3D printing applications for patient implants with particular requirements. PMID:28244880

3D printing PLGA: a quantitative examination of the effects of polymer composition and printing parameters on print resolution.

PubMed

Guo, Ting; Holzberg, Timothy R; Lim, Casey G; Gao, Feng; Gargava, Ankit; Trachtenberg, Jordan E; Mikos, Antonios G; Fisher, John P

2017-04-12

In the past few decades, 3D printing has played a significant role in fabricating scaffolds with consistent, complex structure that meet patient-specific needs in future clinical applications. Although many studies have contributed to this emerging field of additive manufacturing, which includes material development and computer-aided scaffold design, current quantitative analyses do not correlate material properties, printing parameters, and printing outcomes to a great extent. A model that correlates these properties has tremendous potential to standardize 3D printing for tissue engineering and biomaterial science. In this study, we printed poly(lactic-co-glycolic acid) (PLGA) utilizing a direct melt extrusion technique without additional ingredients. We investigated PLGA with various lactic acid:glycolic acid (LA:GA) molecular weight ratios and end caps to demonstrate the dependence of the extrusion process on the polymer composition. Micro-computed tomography was then used to evaluate printed scaffolds containing different LA:GA ratios, composed of different fiber patterns, and processed under different printing conditions. We built a statistical model to reveal the correlation and predominant factors that determine printing precision. Our model showed a strong linear relationship between the actual and predicted precision under different combinations of printing conditions and material compositions. This quantitative examination establishes a significant foreground to 3D print biomaterials following a systematic fabrication procedure. Additionally, our proposed statistical models can be applied to couple specific biomaterials and 3D printing applications for patient implants with particular requirements.

Inverse Analysis of Irradiated NuclearMaterial Gamma Spectra via Nonlinear Optimization

NASA Astrophysics Data System (ADS)

Dean, Garrett James

Nuclear forensics is the collection of technical methods used to identify the provenance of nuclear material interdicted outside of regulatory control. Techniques employed in nuclear forensics include optical microscopy, gas chromatography, mass spectrometry, and alpha, beta, and gamma spectrometry. This dissertation focuses on the application of inverse analysis to gamma spectroscopy to estimate the history of pulse irradiated nuclear material. Previous work in this area has (1) utilized destructive analysis techniques to supplement the nondestructive gamma measurements, and (2) been applied to samples composed of spent nuclear fuel with long irradiation and cooling times. Previous analyses have employed local nonlinear solvers, simple empirical models of gamma spectral features, and simple detector models of gamma spectral features. The algorithm described in this dissertation uses a forward model of the irradiation and measurement process within a global nonlinear optimizer to estimate the unknown irradiation history of pulse irradiated nuclear material. The forward model includes a detector response function for photopeaks only. The algorithm uses a novel hybrid global and local search algorithm to quickly estimate the irradiation parameters, including neutron fluence, cooling time and original composition. Sequential, time correlated series of measurements are used to reduce the uncertainty in the estimated irradiation parameters. This algorithm allows for in situ measurements of interdicted irradiated material. The increase in analysis speed comes with a decrease in information that can be determined, but the sample fluence, cooling time, and composition can be determined within minutes of a measurement. Furthermore, pulse irradiated nuclear material has a characteristic feature that irradiation time and flux cannot be independently estimated. The algorithm has been tested against pulse irradiated samples of pure special nuclear material with cooling times of four minutes to seven hours. The algorithm described is capable of determining the cooling time and fluence the sample was exposed to within 10% as well as roughly estimating the relative concentrations of nuclides present in the original composition.

Optimization of the dynamic behavior of strongly nonlinear heterogeneous materials

NASA Astrophysics Data System (ADS)

Herbold, Eric B.

New aspects of strongly nonlinear wave and structural phenomena in granular media are developed numerically, theoretically and experimentally. One-dimensional chains of particles and compressed powder composites are the two main types of materials considered here. Typical granular assemblies consist of linearly elastic spheres or layers of masses and effective nonlinear springs in one-dimensional columns for dynamic testing. These materials are highly sensitive to initial and boundary conditions, making them useful for acoustic and shock-mitigating applications. One-dimensional assemblies of spherical particles are examples of strongly nonlinear systems with unique properties. For example, if initially uncompressed, these materials have a sound speed equal to zero (sonic vacuum), supporting strongly nonlinear compression solitary waves with a finite width. Different types of assembled metamaterials will be presented with a discussion of the material's response to static compression. The acoustic diode effect will be presented, which may be useful in shock mitigation applications. Systems with controlled dissipation will also be discussed from an experimental and theoretical standpoint emphasizing the critical viscosity that defines the transition from an oscillatory to monotonous shock profile. The dynamic compression of compressed powder composites may lead to self-organizing mesoscale structures in two and three dimensions. A reactive granular material composed of a compressed mixture of polytetrafluoroethylene (PTFE), tungsten (W) and aluminum (Al) fine-grain powders exhibit this behavior. Quasistatic, Hopkinson bar, and drop-weight experiments show that composite materials with a high porosity and fine metallic particles exhibit a higher strength than less porous mixtures with larger particles, given the same mass fraction of constituents. A two-dimensional Eulerian hydrocode is implemented to investigate the mechanical deformation and failure of the compressed powder samples in simulated drop-weight tests. The calculations indicate that the dynamic formation of mesoscale force chains increase the strength of the sample. This is also apparent in three-dimensional finite element calculations of drop-weight test simulations using LS-Dyna despite a higher granular bulk coordination number, and an increased mobility of individual grains.

Bio-Inspired Hierarchical Nanofibrous Fe3O4-TiO2-Carbon Composite as a High-Performance Anode Material for Lithium-Ion Batteries.

PubMed

Li, Shun; Wang, Mengya; Luo, Yan; Huang, Jianguo

2016-07-13

A bioinspired hierarchical nanofibrous Fe3O4-TiO2-carbon composite was fabricated by employing natural cellulose substance (e.g., filter paper) as both the scaffold and the carbon source and showed improved electrochemical performances when it is employed as an anode material for lithium-ion batteries. FeOOH nanoparticles were first grown uniformly onto the surface of the titania thin-layer precoated cellulose nanofibers, and thereafter, the as-prepared FeOOH-TiO2-cellulose composite was calcined and carbonized in argon atmosphere at 500 °C for 6 h to produce the Fe3O4-TiO2-carbon composite. The resultant composite possesses a hierarchical structure that was faithfully inherited from the initial cellulose substance, which was composed of titania-coated carbon fibers with corncob-like shaped Fe3O4 nanoparticles immobilized on the surfaces. The diameter of the composite nanofiber is ca. 100-200 nm, and the diameter of the Fe3O4 nanoparticle is about 30 nm, which is coated with an ultrathin carbon layer with a thickness about 3 nm. This composite displayed superior lithium-ion storage performance. It showed a first-cycle discharge capacity of 1340 mAh/g, delivering a stable reversible capacity of ca. 525 mAh/g after 100 charge-discharge cycles at a current density of 100 mA/g, and the efficiency is as high as ca. 95% of the theoretical value. This is much higher than those of the commercial Fe3O4 powder (160 mAh/g) and the Fe3O4-carbon counter material (310 mAh/g). It was demonstrated that the thin titania precoating layer (thickness ca. 3-5 nm) is necessary for the high content loading of the Fe3O4 nanoparticles onto the carbon nanofibers. Owing to the unique three-dimensional porous network structure of the carbon-fiber scaffold, together with the ultrathin outer carbon-coating layer, the composite showed significantly improved cycling stability and rate capability.

Growth performance and feed conversion efficiency of three edible mealworm species (Coleoptera: Tenebrionidae) on diets composed of organic by-products.

PubMed

van Broekhoven, Sarah; Oonincx, Dennis G A B; van Huis, Arnold; van Loon, Joop J A

2015-02-01

Insects receive increasing attention as an alternative protein-rich food source for humans. Producing edible insects on diets composed of organic by-products could increase sustainability. In addition, insect growth rate and body composition, and hence nutritional quality, can be altered by diet. Three edible mealworm species Tenebrio molitor L., Zophobas atratus Fab. and Alphitobius diaperinus Panzer were grown on diets composed of organic by-products originating from beer brewing, bread/cookie baking, potato processing and bioethanol production. Experimental diets differed with respect to protein and starch content. Larval growth and survival was monitored. Moreover, effects of dietary composition on feed conversion efficiency and mealworm crude protein and fatty acid profile were assessed. Diet affected mealworm development and feed conversion efficiency such that diets high in yeast-derived protein appear favourable, compared to diets used by commercial breeders, with respect to shortening larval development time, reducing mortality and increasing weight gain. Diet also affected the chemical composition of mealworms. Larval protein content was stable on diets that differed 2-3-fold in protein content, whereas dietary fat did have an effect on larval fat content and fatty acid profile. However, larval fatty acid profile did not necessarily follow the same trend as dietary fatty acid composition. Diets that allowed for fast larval growth and low mortality in this study led to a comparable or less favourable n6/n3 fatty acid ratio compared to control diets used by commercial breeders. In conclusion, the mealworm species used in this study can be grown successfully on diets composed of organic by-products. Diet composition did not influence larval protein content, but did alter larval fat composition to a certain extent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Flame Retardant Effect of Aerogel and Nanosilica on Engineered Polymers

NASA Technical Reports Server (NTRS)

Williams, Martha K.; Smith, Trent M.; Roberson, Luke B.; Yang, Feng; Nelson, Gordon L.

2010-01-01

Aerogels are typically manufactured vIa high temperature and pressure-critical-point drying of a colloidal metal oxide gel filled with solvents. Aerogel materials derived from silica materials represent a structural morphology (amorphous, open-celled nanofoams) rather than a particular chemical constituency. Aerogel is not like conventional foams in that it is a porous material with extreme microporosity and composed of individual features only a few nanometers in length with a highly porous dendriticlike structure. This unique substance has unusual properties such as low thermal conductivity, refractive index and sound suppression; in addition to its exceptional ability to capture fast moving dust. The highly porous nature of the aerogel's structure provides large amounts of surface area per unit weight. For instance, a silica aerogel material with a density of 100 kilograms per cubic meters can have surface areas of around 800 to 1500 square meters per gram depending on the precursors and process utilized to produce it. To take advantage of the unique properties of silica aerogels, especially the ultra light weight and low thermal conductivity, their composites with various engineering polymers were prepared and their flammability was investigated by Cone Calorimetry. The flammability of various polystyrene/silica aerogel nanocomposites were measured. The combination of these nanocomposites with a NASA patented flame retardant SINK were also studied. The results were compared with the base polymer to show the differences between composites with different forms of silica.

Specific features of basalts from the western part of Andrew Bain Fault, Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Peyve, A. A.; Skolotnev, S. G.

2017-12-01

This paper reports original data on the composition of volcanic rocks in the western part of the Andrew Bain Fault of the South-West Indian Ridge obtained in the 23rd voyage of R/V Akademik Nikolai Strakhov. In accordance with high La/Th and low Nb/U ratios, the basalt compositions of stations S2317, S2318, and S2330 could result from melting of the DM-type source with HIMU traces. Meanwhile, the enriched samples of station S2326 correspond to a mantle source with a considerable contribution of recycled sediments (EM). Sample S2326/35, which is composed of a melt almost completely depleted in EM material, corresponds to the volcanic rocks of the Marion and Prince Edward islands. The obtained and available data on the SWIR segment from Bouvet Island to Andrew Bain Fault are indicative of small mantle heterogeneities in this region. Two possible variants of their origin are considered: either preservation of the enriched material fragments in the depleted mantle during the split of Gondwana or "contamination" of the mantle with plume material with the formation of vein irregularities before opening of the ocean in this region. In the latter case, the plume material could cover a huge area not constrained by the young plume magmatism regions on Bouvet, Marion, and Prince Edward islands.

Effect of electrical current on the tribological behavior of the Cu-WS2-G composites in air and vacuum

NASA Astrophysics Data System (ADS)

Qian, Gang; Feng, Yi; Li, Bin; Huang, Shiyin; Liu, Hongjuan; Ding, Kewang

2013-03-01

As the traditional graphite-based composites cannot meet the requirement of rapid developing modern industry, novel sliding electrical contact materials with high self-lubricating performance in multiple environments are eagerly required. Herein a copper-based composite with WS2 and graphite as solid lubricant are fabricated by powder metallurgy hot-pressed method. The friction and wear behaviors of the composites with and without current are investigated under the condition with sliding velocity of 10 m/s and normal load of 2.5 N/cm2 in both air and vacuum. Morphologies of the worn surfaces are observed by optical microscope and compositions of the lubricating films are analyzed by XPS. Surface profile curves and roughness of the worn surfaces are obtained by 2205 surface profiler. The results of wear tests show that the friction coefficient and wear volume loss of the composites with current are greater than that without current in both air and vacuum due to the adverse effects of electrical current which damaged the lubricating film partially and roughed the worn surfaces. XPS results demonstrate that the lubricating film formed in air is composed of oxides of Cu, WS2, elemental S and graphite, while the lubricating film formed in vacuum is composed of Cu, WS2 and graphite. Because of the synergetic lubricating action of oxides of Cu, WS2 and graphite, the composites show low friction coefficient and wear volume loss in air condition. Owing to the fact that graphite loses its lubricity which makes WS2 become the only lubricant, severe adhesive and abrasive wear occur and result in a high value of wear rate in vacuum condition. The formation of the lubricating film on the contact interface between the brush and ring is one of the factors which can greatly affect the wear performance of the brushes. The low contact voltage drop of the composites in vacuum condition is attributed to the high content of Cu in the surface film. This study fabricated a kind of new sliding electrical contact self-lubricating composite with dual-lubricant which can work well in both air and vacuum environments and provides a comprehensive analysis on the lubrication mechanisms of the composite.

Gas Evolution from Insulating Materials for Superconducting Coil of Iter by Gamma Ray Irradiation at Liquid Nitrogen Temperature

NASA Astrophysics Data System (ADS)

Idesaki, A.; Koizumi, N.; Sugimoto, M.; Morishita, N.; Ohshima, T.; Okuno, K.

2008-03-01

A laminated material composed of glass cloth/polyimide film/epoxy resin will be used as an insulating material for superconducting coil of International Thermonuclear Experimental Reactor (ITER). In order to keep safe and stable operation of the superconducting coil system, it is indispensable to evaluate radiation resistance of the material, because the material is exposed to severe environments such as high radiation field and low temperature of 4 K. Especially, it is important to estimate the amount of gases evolved from the insulating material by irradiation, because the gases affect on the purifying system of liquid helium in the superconducting coil system. In this work, the gas evolution from the laminated material by gamma ray irradiation at liquid nitrogen temperature (77 K) was investigated, and the difference of gas evolution behavior due to difference of composition in the epoxy resin was discussed. It was found that the main gases evolved from the laminated material by the irradiation were hydrogen, carbon monoxide and carbon dioxide, and that the amount of gases evolved from the epoxy resin containing cyanate ester was about 60% less than that from the epoxy resin containing tetraglycidyl-diaminophenylmethane (TGDDM).

Advanced materials for radiation-cooled rockets

NASA Technical Reports Server (NTRS)

Reed, Brian; Biaglow, James; Schneider, Steven

1993-01-01

The most common material system currently used for low thrust, radiation-cooled rockets is a niobium alloy (C-103) with a fused silica coating (R-512A or R-512E) for oxidation protection. However, significant amounts of fuel film cooling are usually required to keep the material below its maximum operating temperature of 1370 C, degrading engine performance. Also the R-512 coating is subject to cracking and eventual spalling after repeated thermal cycling. A new class of high-temperature, oxidation-resistant materials are being developed for radiation-cooled rockets, with the thermal margin to reduce or eliminate fuel film cooling, while still exceeding the life of silicide-coated niobium. Rhenium coated with iridium is the most developed of these high-temperature materials. Efforts are on-going to develop 22 N, 62 N, and 440 N engines composed of these materials for apogee insertion, attitude control, and other functions. There is also a complimentary NASA and industry effort to determine the life limiting mechanisms and characterize the thermomechanical properties of these materials. Other material systems are also being studied which may offer more thermal margin and/or oxidation resistance, such as hafnium carbide/tantalum carbide matrix composites and ceramic oxide-coated iridium/rhenium chambers.

Associative Flow Rule Used to Include Hydrostatic Stress Effects in Analysis of Strain-Rate-Dependent Deformation of Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Roberts, Gary D.

2004-01-01

designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. The nonlinearity and the strain-rate dependence of the composite response are due primarily to the matrix constituent. Therefore, in developing material models to be used in the design of impact-resistant composite engine cases, the deformation of the polymer matrix must be correctly analyzed. However, unlike in metals, the nonlinear response of polymers depends on the hydrostatic stresses, which must be accounted for within an analytical model. By applying micromechanics techniques along with given fiber properties, one can also determine the effects of the hydrostatic stresses in the polymer on the overall composite deformation response. First efforts to account for the hydrostatic stress effects in the composite deformation applied purely empirical methods that relied on composite-level data. In later efforts, to allow polymer properties to be characterized solely on the basis of polymer data, researchers at the NASA Glenn Research Center developed equations to model the polymers that were based on a non-associative flow rule, and efforts to use these equations to simulate the deformation of representative polymer materials were reasonably successful. However, these equations were found to have difficulty in correctly analyzing the multiaxial stress states found in the polymer matrix constituent of a composite material. To correct these difficulties, and to allow for the accurate simulation of the nonlinear strain-rate-dependent deformation analysis of polymer matrix composites, in the efforts reported here Glenn researchers reformulated the polymer constitutive equations from basic principles using the concept of an associative flow rule. These revised equations were characterized and validated in an experimental program carried out through a university grant with the Ohio State University, wherein tensile and shear deformation data were obtained for a representative polymer for strain rates ranging from quasi-static to high rates of several hundred per second. Tensile deformation data also were obtained over a variety of strain rates and fiber orientation angles for a representative polymer matrix composite composed using the polymer.

Unskilled Writers as Composers.

ERIC Educational Resources Information Center

Perl, Sondra

1979-01-01

Composition is not a straightforward, linear process; it involves a creative search for meaning that becomes clear only as the writer engages in the composing process. This suggests that teaching not dwell on the correctness of the finished product. (Author/SJL)

Behaviour of partially composite precast concrete sandwich panels under flexural and axial loads

NASA Astrophysics Data System (ADS)

Tomlinson, Douglas George

Precast concrete sandwich panels are commonly used on building exteriors. They are typically composed of two concrete wythes that surround rigid insulation. They are advantageous as they provide both structural and thermal resistance. The structural response of sandwich panels is heavily influenced by shear connectors that link the wythes together. This thesis presents a study on partially composite non-prestressed precast concrete wall panels. Nine flexure tests were conducted on a wall design incorporating 'floating' concrete studs and Glass Fibre Reinforced Polymer (GFRP) connectors. The studs encapsulate and stiffen the connectors, reducing shear deformations. Ultimate loads increased from 58 to 80% that of a composite section as the connectors' reinforcement ratio increased from 2.6 to 9.8%. This design was optimized by reinforcing the studs and integrating them with the structural wythe; new connectors composed of angled steel or Basalt-FRP (BFRP) were used. The load-slip response of the new connector design was studied through 38 double shear push-through tests using various connector diameters and insertion angles. Larger connectors were stronger but more likely to pull out. Seven flexure tests were conducted on the new wall design reinforced with different combinations of steel and BFRP connectors and reinforcement. Composite action varied from 50 to 90% depending on connector and reinforcement material. Following this study, the axial-bending interaction curves were established for the new wall design using both BFRP and steel connectors and reinforcement. Eight panels were axially loaded to predesignated loads then loaded in flexure to failure. A technique is presented to experimentally determine the effective centroid of partially composite sections. Beyond the tension and compression-controlled failure regions of the interaction curve, a third region was observed in between, governed by connector failure. Theoretical models were developed for the bond-slip behaviour of the shear connection and to analyze the full panel's flexural and axial response to determine the longitudinal shear force transferred between wythes and account for partial composite behavior. The models were validated against experiments and used to conduct a parametric study. Among several interesting findings, the study demonstrated how composite action increases with the slenderness of axially loaded panels.

Vision loss and hearing loss in painting and musical composition.

PubMed

Marmor, Michael F

2014-07-01

This article considers the impact of vision and hearing loss on great painters and musical composers. The visual work of Mary Cassatt, Georgia O'Keeffe, Edgar Degas, and Claude Monet all showed alterations as their vision failed. In contrast, Gabriel Fauré, Bedřich Smetana, and Ludwig von Beethoven wrote many of their best compositions while totally deaf, and Georg Friedrich Handel and Frederick Delius struggled to compose late in life when they lost their vision (although their hearing remained excellent). There are 2 major distinctions between the role of vision and hearing for these artistic disciplines. First, there is a surrogate means of "hearing" music, through the musical score, which allows composers to write and edit music while totally deaf. The greatest problem with deafness for a skilled composer is interference from internal noise (tinnitus). There is no surrogate for vision to allow a painter to work when the subject is a blur or the colors on the canvas cannot be distinguished. Second, although the appreciation of art is visual and that of music is auditory, the transcription of both art and musical composition is visual. Thus, visual loss does pose a problem for a composer accustomed to working with good sight, because it disrupts habitual methods of writing and editing music. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Hierarchical Tubular Structures Composed of Co3 O4 Hollow Nanoparticles and Carbon Nanotubes for Lithium Storage.

PubMed

Chen, Yu Ming; Yu, Le; Lou, Xiong Wen David

2016-05-10

Hierarchical tubular structures composed of Co3 O4 hollow nanoparticles and carbon nanotubes (CNTs) have been synthesized by an efficient multi-step route. Starting from polymer-cobalt acetate (Co(Ac)2 ) composite nanofibers, uniform polymer-Co(Ac)2 @zeolitic imidazolate framework-67 (ZIF-67) core-shell nanofibers are first synthesized via partial phase transformation with 2-methylimidazole in ethanol. After the selective dissolution of polymer-Co(Ac)2 cores, the resulting ZIF-67 tubular structures can be converted into hierarchical CNTs/Co-carbon hybrids by annealing in Ar/H2 atmosphere. Finally, the hierarchical CNT/Co3 O4 microtubes are obtained by a subsequent thermal treatment in air. Impressively, the as-prepared nanocomposite delivers a high reversible capacity of 1281 mAh g(-1) at 0.1 A g(-1) with exceptional rate capability and long cycle life over 200 cycles as an anode material for lithium-ion batteries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A monoclinic, pseudo-orthorhombic Au-Hg mineral of potential economic significance in Pleistocene Snake River alluvial deposits of southeastern Idaho

USGS Publications Warehouse

Desborough, G.A.; Foord, E.E.

1992-01-01

A mineral with the approximate composition of Au94Hg6 - Au88Hg12 (atomic %) has been identified in Pleistocene Snake River alluvial deposits. The gold-mercury mineral occurs as very small grains or as polycrystalline masses composed of subhedral to nearly euhedral attached crystals. Vibratory cold-polishing techniques with 0.05-??m alumina abrasive for polished sections revealed a porous internal texture for most subhedral crystals after 48-72 hours of treatment. Thus, optical character (isotropic or anisotropic) could not be determined by reflected-light microscopy, and pore-free areas were too small for measurement of reflectance. X-ray-diffraction lines rather than individual reflections (spots), on powder camera X-ray films of unrotated spindles of single grains that morphologically appear to be single crystals, indicate that individual subhedral or euhedral crystals are composed of domains in random orientation. Thus, no material was found suitable for single-crystal X-ray diffraction studies. -from Authors

Ultra-large supramolecular coordination cages composed of endohedral Archimedean and Platonic bodies

NASA Astrophysics Data System (ADS)

Byrne, Kevin; Zubair, Muhammad; Zhu, Nianyong; Zhou, Xiao-Ping; Fox, Daniel S.; Zhang, Hongzhou; Twamley, Brendan; Lennox, Matthew J.; Düren, Tina; Schmitt, Wolfgang

2017-05-01

Pioneered by Lehn, Cram, Peterson and Breslow, supramolecular chemistry concepts have evolved providing fundamental knowledge of the relationships between the structures and reactivities of organized molecules. A particular fascinating class of metallo-supramolecular molecules are hollow coordination cages that provide cavities of molecular dimensions promoting applications in diverse areas including catalysis, enzyme mimetics and material science. Here we report the synthesis of coordination cages with exceptional cross-sectional diameters that are composed of multiple sub-cages providing numerous distinctive binding sites through labile coordination solvent molecules. The building principles, involving Archimedean and Platonic bodies, renders these supramolecular keplerates as a class of cages whose composition and topological aspects compare to characteristics of edge-transitive {Cu2} MOFs with A3X4 stoichiometry. The nature of the cavities in these double-shell metal-organic polyhedra and their inner/outer binding sites provide perspectives for post-synthetic functionalizations, separations and catalysis. Transmission electron microscopy studies demonstrate that single molecules are experimentally accessible.

Ultra-large supramolecular coordination cages composed of endohedral Archimedean and Platonic bodies

PubMed Central

Byrne, Kevin; Zubair, Muhammad; Zhu, Nianyong; Zhou, Xiao-Ping; Fox, Daniel S.; Zhang, Hongzhou; Twamley, Brendan; Lennox, Matthew J.; Düren, Tina; Schmitt, Wolfgang

2017-01-01

Pioneered by Lehn, Cram, Peterson and Breslow, supramolecular chemistry concepts have evolved providing fundamental knowledge of the relationships between the structures and reactivities of organized molecules. A particular fascinating class of metallo-supramolecular molecules are hollow coordination cages that provide cavities of molecular dimensions promoting applications in diverse areas including catalysis, enzyme mimetics and material science. Here we report the synthesis of coordination cages with exceptional cross-sectional diameters that are composed of multiple sub-cages providing numerous distinctive binding sites through labile coordination solvent molecules. The building principles, involving Archimedean and Platonic bodies, renders these supramolecular keplerates as a class of cages whose composition and topological aspects compare to characteristics of edge-transitive {Cu2} MOFs with A3X4 stoichiometry. The nature of the cavities in these double-shell metal-organic polyhedra and their inner/outer binding sites provide perspectives for post-synthetic functionalizations, separations and catalysis. Transmission electron microscopy studies demonstrate that single molecules are experimentally accessible. PMID:28485392

Optimization extraction of polysaccharide from Tunisian Zizyphus lotus fruit by response surface methodology: Composition and antioxidant activity.

PubMed

Mkadmini Hammi, Khaoula; Hammami, Majdi; Rihouey, Christophe; Le Cerf, Didier; Ksouri, Riadh; Majdoub, Hatem

2016-12-01

Response surface methodology using a Box-Behnken design was employed to optimize extraction temperature, extraction time and ratio of water to material to obtain a maximum polysaccharide yield with high uronic acid content and antioxidant property from edible Zizyphus lotus fruit. The optimal conditions were: extraction time of 3h 15min, extraction temperature of 91.2°C and water to solid ratio of 39mL/g. Under these conditions, the experimental extraction yield, uronic acid content and 2,2-diphenyl-1-picrylhydrazyl scavenging ability (IC50) were 18.88%, 41.89 and 0.518mg/mL, respectively. Chemical analysis revealed that the extract was composed of 97.92% carbohydrate of which 41.89% is uronic acid. The extracted polysaccharides, with an average molecular weight of 2720kDa, are composed of arabinose, rhamnose, glucose, fructose, galactose and xylose. Moreover, the polysaccharides exhibited a significant reducing power and anti-lipid peroxidation activities. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation of MgO-SnO2-TiO2 Materials and Their Corrosion in Na3AlF6-AlF3-K3AlF6 Bath

NASA Astrophysics Data System (ADS)

Xu, Yibiao; Li, Yawei; Sang, Shaobai; Ren, Bo; Qin, Qingwei; Yang, Jianhong

2015-01-01

New types of refractory materials need to be developed for designing the so-called ledge-free sidewalls of the Hall-Héroult cell for aluminum extraction, which are currently constructed using Si3N4 bonded SiC refractories. In the present paper, MgO-based materials as potential candidate sidewalls were prepared using fused magnesia, tin dioxide, and anatase powder as starting materials. The reaction sintering process of the MgO-SnO2-TiO2 materials was investigated by means of X-ray diffraction and scanning electron microscope (SEM). All the specimens were corroded in a Na3AlF6-AlF3-K3AlF6 bath to assess the electrolyte corrosion resistance. The results show that reaction sintering occurs in the MgO-SnO2-TiO2 system in the range of 1373 K to 1873 K (1100 °C to 1600 °C). Firstly, MgO reacts separately with TiO2 and SnO2 to produce the Mg2TiO4 and Mg2SnO4 phases at 1373 K (1100 °C), which in turn react to form the Mg2Ti x Sn1-x O4 composite spinel at temperatures above 1373 K (1100 °C). All the specimens prepared are composed of the composite spinel and periclase phases. Increasing the SnO2 addition from 2 to 10 wt pct enhances densification of the specimens, which is accompanied by the formation of homogeneously distributed composite spinels in the MgO matrix, but the density of the specimen decreases when the amount of SnO2 added is higher than 10 wt pct due to larger volume expansion and agglomeration of the composite spinel. The MgO-SnO2-TiO2 refractories prepared exhibit good corrosion resistance to the electrolyte melts owing to their high density and formation of the composite spinel in the specimens. Their corrosion resistance increases progressively with the increase in the SnO2 addition owing to the formation of more chemically stable composite spinel.

A carbon and nitrogen isotope study of carbonaceous vein material in ureilite meteorites

NASA Technical Reports Server (NTRS)

Russell, S. S.; Arden, J. W.; Franchi, I. A.; Pillinger, C. T.

1993-01-01

The ureilite meteorite group is known to be rich in carbon in the form of graphite/diamond veins that are associated with planetary type noble gases. This paper reports preliminary data from a systematic study of the carbon and nitrogen isotopic composition of this carbonaceous vein material. A previous study focused on the whole rock signatures and reported that the carbon inventory appeared to be dominated by the graphitic/diamond intergrowths, whereas the nitrogen was clearly composed of several distinct components including one that was isotopically light, possibly associated with the carbonaceous material. Recent studies have demonstrated that diamonds in the solar system formed in many different environments. C and N measurements from ureilitic diamond made in a similar way would be a useful addition to this overall study. The methods used for isolating diamonds of possible presolar origin from primitive meteorites are equally applicable to the processing of carbon bearing components in the ureilite group so that their stable isotopic composition can be determined. Herein we discuss conjoint C and N stepped combustion measurements made on crushed whole rock ureilite samples that have been treated with 1M HCl/9M HF to dissolve silicate and free metal. In addition, two samples have been further treated with oxidizing acids to leave a diamond rich residue.

High-Capacity and Photoregenerable Composite Material for Efficient Adsorption and Degradation of Phenanthrene in Water.

PubMed

Liu, Wen; Cai, Zhengqing; Zhao, Xiao; Wang, Ting; Li, Fan; Zhao, Dongye

2016-10-18

We report a novel composite material, referred to as activated charcoal supported titanate nanotubes (TNTs@AC), for highly efficient adsorption and photodegradation of a representative polycyclic aromatic hydrocarbon (PAH), phenanthrene. TNTs@AC was prepared through a one-step hydrothermal method, and is composed of an activated charcoal core and a shell of carbon-coated titanate nanotubes. TNTs@AC offered a maximum Langmuir adsorption capacity of 12.1 mg/g for phenanthrene (a model PAH), which is ∼11 times higher than the parent activated charcoal. Phenanthrene was rapidly concentrated onto TNTs@AC, and subsequently completely photodegraded under UV light within 2 h. The photoregenerated TNTs@AC can then be reused for another adsorption-photodegradation cycle without significant capacity or activity loss. TNTs@AC performed well over a wide range of pH, ionic strength, and dissolved organic matter. Mechanistically, the enhanced adsorption capacity is attributed to the formation of carbon-coated ink-bottle pores of the titanate nanotubes, which are conducive to capillary condensation; in addition, the modified microcarbon facilitates transfer of excited electrons, thereby inhibiting recombination of the electron-hole pairs, resulting in high photocatalytic activity. The combined high adsorption capacity, photocatalytic activity, and regenerability/reusability merit TNTs@AC a very attractive material for concentrating and degrading a host of micropollutants in the environment.

Perovskite-Inspired Photovoltaic Materials: Toward Best Practices in Materials Characterization and Calculations

DOE PAGES

Hoye, Robert L. Z.; Schulz, Philip; Schelhas, Laura T.; ...

2017-02-28

Recently, there has been an explosive growth in research based on hybrid lead-halide perovskites for photovoltaics owing to rapid improvements in efficiency. The advent of these materials for solar applications has led to widespread interest in understanding the key enabling properties of these materials. This has resulted in renewed interest in related compounds and a search for materials that may replicate the defect-tolerant properties and long lifetimes of the hybrid lead-halide perovskites. Given the rapid pace of development of the field, the rises in efficiencies of these systems have outpaced the more basic understanding of these materials. Measuring or calculatingmore » the basic properties, such as crystal/electronic structure and composition, can be challenging because some of these materials have anisotropic structures, and/or are composed of both heavy metal cations and volatile, mobile, light elements. Some consequences are beam damage during characterization, composition change under vacuum, or compound effects, such as the alteration of the electronic structure through the influence of the substrate. These effects make it challenging to understand the basic properties integral to optoelectronic operation. Compounding these difficulties is the rapid pace with which the field progresses. This has created an ongoing need to continually evaluate best practices with respect to characterization and calculations, as well as to identify inconsistencies in reported values to determine if those inconsistencies are rooted in characterization methodology or materials synthesis. This article describes the difficulties in characterizing hybrid lead-halide perovskites and new materials and how these challenges may be overcome. The topic was discussed at a seminar at the 2015 Materials Research Society Fall Meeting & Exhibit. This article highlights the lessons learned from the seminar and the insights of some of the attendees, with reference to both recent literature and controlled experiments to illustrate the challenges discussed. The focus in this article is on crystallography, composition measurements, photoemission spectroscopy, and calculations on perovskites and new, related absorbers. We suggest how the reporting of the important artifacts could be streamlined between groups to ensure reproducibility as the field progresses.« less

Perovskite-Inspired Photovoltaic Materials: Toward Best Practices in Materials Characterization and Calculations

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

Hoye, Robert L. Z.; Schulz, Philip; Schelhas, Laura T.

Recently, there has been an explosive growth in research based on hybrid lead-halide perovskites for photovoltaics owing to rapid improvements in efficiency. The advent of these materials for solar applications has led to widespread interest in understanding the key enabling properties of these materials. This has resulted in renewed interest in related compounds and a search for materials that may replicate the defect-tolerant properties and long lifetimes of the hybrid lead-halide perovskites. Given the rapid pace of development of the field, the rises in efficiencies of these systems have outpaced the more basic understanding of these materials. Measuring or calculatingmore » the basic properties, such as crystal/electronic structure and composition, can be challenging because some of these materials have anisotropic structures, and/or are composed of both heavy metal cations and volatile, mobile, light elements. Some consequences are beam damage during characterization, composition change under vacuum, or compound effects, such as the alteration of the electronic structure through the influence of the substrate. These effects make it challenging to understand the basic properties integral to optoelectronic operation. Compounding these difficulties is the rapid pace with which the field progresses. This has created an ongoing need to continually evaluate best practices with respect to characterization and calculations, as well as to identify inconsistencies in reported values to determine if those inconsistencies are rooted in characterization methodology or materials synthesis. This article describes the difficulties in characterizing hybrid lead-halide perovskites and new materials and how these challenges may be overcome. The topic was discussed at a seminar at the 2015 Materials Research Society Fall Meeting & Exhibit. This article highlights the lessons learned from the seminar and the insights of some of the attendees, with reference to both recent literature and controlled experiments to illustrate the challenges discussed. The focus in this article is on crystallography, composition measurements, photoemission spectroscopy, and calculations on perovskites and new, related absorbers. We suggest how the reporting of the important artifacts could be streamlined between groups to ensure reproducibility as the field progresses.« less

Design and fabrication of advanced materials from Illinois coal wastes. Quarterly report, 1 March 1995--31 May 1995

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

Malhotra, V.M.; Wright, M.A.

1995-12-31

The main goal of this project is to develop a bench-scale procedure to design and fabricate advanced brake and structural composite materials from Illinois coal combustion residues. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), differential thermal analysis (DTA), and transmission-Fourier transform infrared (FTIR) were conducted on PCC fly ash (Baldwin), FBC fly ash (ADM unit1-6), FBC fly ash (S.I. coal), FBC spent bed ash (ADM unit1-6), bottom ash, and scrubber sludge (CWLP) residues to characterize their geometrical shapes, mineral phases, and thermal stability. Our spectroscopic results indicate that the scrubber sludge is mainly composed of a gypsum-like phase whosemore » lattice structure is different from the lattice structure of conventional gypsum, and sludge does not contain hannebachite (CaSO{sub 3}0.5H{sub 2}O) phase. In the second and third quarters the focus of research has been on developing protocols for the formation of advanced brake composites and structural composites. Our attempts to fabricate brake frictional shoes, in the form of 1.25 inch disks, from PCC fly ash, FBC spent bed ash, scrubber sludge, coal char, iron particles, and coal tar were successful. Based on the experience gained and microscopic analyses, we have now upscaled our procedures to fabricate 2.5 inch diameter disks from coal combustion residues. The SEM and Young`s modulus analyses of brake composites fabricated at 400 psi < Pressure < 2200 psi suggest pressure has a strong influence on the particle packing and the filling of interstices in our composites.« less

Analytical Modeling of the High Strain Rate Deformation of Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Roberts, Gary D.; Gilat, Amos

2003-01-01

The results presented here are part of an ongoing research program to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric matrix materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical 5 plasticity theory definitions of effective stress and effective plastic strain are modified by applying variations of the Drucker-Prager yield criterion. To verify the revised formulation, the shear and tensile deformation of a representative toughened epoxy is analyzed across a wide range of strain rates (from quasi-static to high strain rates) and the results are compared to experimentally obtained values. For the analyzed polymers, both the tensile and shear stress-strain curves computed using the analytical model correlate well with values obtained through experimental tests. The polymer constitutive equations are implemented within a strength of materials based micromechanics method to predict the nonlinear, strain rate dependent deformation of polymer matrix composites. In the micromechanics, the unit cell is divided up into a number of independently analyzed slices, and laminate theory is then applied to obtain the effective deformation of the unit cell. The composite mechanics are verified by analyzing the deformation of a representative polymer matrix composite (composed using the representative polymer analyzed for the correlation of the polymer constitutive equations) for several fiber orientation angles across a variety of strain rates. The computed values compare favorably to experimentally obtained results.

Musical and poetic creativity and epilepsy.

PubMed

Hesdorffer, Dale C; Trimble, Michael

2016-04-01

Associations between epilepsy and musical or poetic composition have received little attention. We reviewed the literature on links between poetic and musical skills and epilepsy, limiting this to the Western canon. While several composers were said to have had epilepsy, John Hughes concluded that none of the major classical composers thought to have had epilepsy actually had it. The only composer with epilepsy that we could find was the contemporary composer, Hikari Oe, who has autism and developed epilepsy at age 15years. In his childhood years, his mother found that he had an ability to identify bird sound and keys of songs and began teaching him piano. Hikari is able to compose in his head when his seizures are not severe, but when his seizures worsen, his creativity is lost. Music critics have commented on the simplicity of his musical composition and its monotonous sound. Our failure to find evidence of musical composers with epilepsy finds parallels with poetry where there are virtually no established poets with epilepsy. Those with seizures include Lord George Byron in the setting of terminal illness, Algernon Swinburne who had alcohol-related seizures, Charles Lloyd who had seizures and psychosis, Edward Lear who had childhood onset seizures, and Vachel Lindsay. The possibility that Emily Dickinson had epilepsy is also discussed. It has not been possible to identify great talents with epilepsy who excel in poetic or musical composition. There are few published poets with epilepsy and no great composers. Why is this? Similarities between music and poetry include meter, tone, stress, rhythm, and form, and much poetry is sung with music. It is likely that great musical and poetic compositions demand a greater degree of concentration and memory than is possible in epilepsy, resulting in problems retaining a musical and mathematical structure over time. The lack of association between recognizable neuropsychiatric disorders and these skills is a gateway to understanding facets of the relationship between the brain and creativity. This article is part of a Special Issue entitled "Epilepsy, Art, and Creativity". Copyright © 2015. Published by Elsevier Inc.

Major changes in microbial diversity and community composition across gut sections of a juvenile Panchlora cockroach

PubMed Central

Gontang, Erin A.; Aylward, Frank O.; Carlos, Camila; Glavina del Rio, Tijana; Chovatia, Mansi; Fern, Alison; Lo, Chien-Chi; Malfatti, Stephanie A.; Tringe, Susannah G.; Currie, Cameron R.; Kolter, Roberto

2017-01-01

Investigations of gut microbiomes have shed light on the diversity and genetic content of these communities, and helped shape our understanding of how host-associated microorganisms influence host physiology, behavior, and health. Despite the importance of gut microbes to metazoans, our understanding of the changes in diversity and composition across the alimentary tract, and the source of the resident community are limited. Here, using community metagenomics and 16S rRNA gene sequencing, we assess microbial community diversity and coding potential in the foregut, midgut, and hindgut of a juvenile Panchlora cockroach, which resides in the refuse piles of the leaf-cutter ant species Atta colombica. We found a significant shift in the microbial community structure and coding potential throughout the three gut sections of Panchlora sp., and through comparison with previously generated metagenomes of the cockroach’s food source and niche, we reveal that this shift in microbial community composition is influenced by the ecosystems in which Panchlora sp. occurs. While the foregut is composed of microbes that likely originate from the symbiotic fungus gardens of the ants, the midgut and hindgut are composed of a microbial community that is likely cockroach-specific. Analogous to mammalian systems, the midgut and hindgut appear to be dominated by Firmicutes and Bacteroidetes with the capacity for polysaccharide degradation, suggesting they may assist in the degradation of dietary plant material. Our work underscores the prominence of community changes throughout gut microbiomes and highlights ecological factors that underpin the structure and function of the symbiotic microbial communities of metazoans. PMID:28545131

Major changes in microbial diversity and community composition across gut sections of a juvenile Panchlora cockroach

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

Gontang, Erin A.; Aylward, Frank O.; Carlos, Camila

Investigations of gut microbiomes have shed light on the diversity and genetic content of these communities, and helped shape our understanding of how host-associated microorganisms influence host physiology, behavior, and health. Despite the importance of gut microbes to metazoans, our understanding of the changes in diversity and composition across the alimentary tract, and the source of the resident community are limited. Here, using community metagenomics and 16S rRNA gene sequencing, we assess microbial community diversity and coding potential in the foregut, midgut, and hindgut of a juvenile Panchlora cockroach, which resides in the refuse piles of the leaf-cutter ant speciesmore » Atta colombica. We found a significant shift in the microbial community structure and coding potential throughout the three gut sections of Panchlora sp., and through comparison with previously generated metagenomes of the cockroach's food source and niche, we reveal that this shift in microbial community composition is influenced by the ecosystems in which Panchlora sp. occurs. While the foregut is composed of microbes that likely originate from the symbiotic fungus gardens of the ants, the midgut and hindgut are composed of a microbial community that is likely cockroach-specific. Analogous to mammalian systems, the midgut and hindgut appear to be dominated by Firmicutes and Bacteroidetes with the capacity for polysaccharide degradation, suggesting they may assist in the degradation of dietary plant material. Our work underscores the prominence of community changes throughout gut microbiomes and highlights ecological factors that underpin the structure and function of the symbiotic microbial communities of metazoans.« less

Major changes in microbial diversity and community composition across gut sections of a juvenile Panchlora cockroach

DOE PAGES

Gontang, Erin A.; Aylward, Frank O.; Carlos, Camila; ...

2017-05-18

Investigations of gut microbiomes have shed light on the diversity and genetic content of these communities, and helped shape our understanding of how host-associated microorganisms influence host physiology, behavior, and health. Despite the importance of gut microbes to metazoans, our understanding of the changes in diversity and composition across the alimentary tract, and the source of the resident community are limited. Here, using community metagenomics and 16S rRNA gene sequencing, we assess microbial community diversity and coding potential in the foregut, midgut, and hindgut of a juvenile Panchlora cockroach, which resides in the refuse piles of the leaf-cutter ant speciesmore » Atta colombica. We found a significant shift in the microbial community structure and coding potential throughout the three gut sections of Panchlora sp., and through comparison with previously generated metagenomes of the cockroach's food source and niche, we reveal that this shift in microbial community composition is influenced by the ecosystems in which Panchlora sp. occurs. While the foregut is composed of microbes that likely originate from the symbiotic fungus gardens of the ants, the midgut and hindgut are composed of a microbial community that is likely cockroach-specific. Analogous to mammalian systems, the midgut and hindgut appear to be dominated by Firmicutes and Bacteroidetes with the capacity for polysaccharide degradation, suggesting they may assist in the degradation of dietary plant material. Our work underscores the prominence of community changes throughout gut microbiomes and highlights ecological factors that underpin the structure and function of the symbiotic microbial communities of metazoans.« less

Major changes in microbial diversity and community composition across gut sections of a juvenile Panchlora cockroach.

PubMed

Gontang, Erin A; Aylward, Frank O; Carlos, Camila; Glavina Del Rio, Tijana; Chovatia, Mansi; Fern, Alison; Lo, Chien-Chi; Malfatti, Stephanie A; Tringe, Susannah G; Currie, Cameron R; Kolter, Roberto

2017-01-01

Investigations of gut microbiomes have shed light on the diversity and genetic content of these communities, and helped shape our understanding of how host-associated microorganisms influence host physiology, behavior, and health. Despite the importance of gut microbes to metazoans, our understanding of the changes in diversity and composition across the alimentary tract, and the source of the resident community are limited. Here, using community metagenomics and 16S rRNA gene sequencing, we assess microbial community diversity and coding potential in the foregut, midgut, and hindgut of a juvenile Panchlora cockroach, which resides in the refuse piles of the leaf-cutter ant species Atta colombica. We found a significant shift in the microbial community structure and coding potential throughout the three gut sections of Panchlora sp., and through comparison with previously generated metagenomes of the cockroach's food source and niche, we reveal that this shift in microbial community composition is influenced by the ecosystems in which Panchlora sp. occurs. While the foregut is composed of microbes that likely originate from the symbiotic fungus gardens of the ants, the midgut and hindgut are composed of a microbial community that is likely cockroach-specific. Analogous to mammalian systems, the midgut and hindgut appear to be dominated by Firmicutes and Bacteroidetes with the capacity for polysaccharide degradation, suggesting they may assist in the degradation of dietary plant material. Our work underscores the prominence of community changes throughout gut microbiomes and highlights ecological factors that underpin the structure and function of the symbiotic microbial communities of metazoans.

The Use of Tribocharging in the Electrostatic Beneficiation of Lunar Simulant

NASA Technical Reports Server (NTRS)

Trigwell, S.; Captain, J. G.; Arens, E. E.; Captain, J. E.; Quinn, J. W.; Calle, C. I.

2007-01-01

Any future lunar base and habitat must be constructed from strong dense materials in order to provide for thermal and radiation protection. Lunar soil may meet this need. Lunar regolith has high concentrations of aluminum, silicon, calcium, iron, sodium, and titanium oxides. Refinement or enrichment of specific minerals in the soil before it is chemically processed may be more desirable as it would reduce the size and energy requirements required to produce the virgin material and it may significantly reduce the process' complexity. Also, investigations into the potential production of breathable oxygen from oxidized mineral components are a major research initiative by NASA. In this study. the objective was to investigate the use of tribocharging to charge lunar simulants and pass them through a parallel plate separator to enrich different mineral fractions. This technique takes advantage of the high Lunar vacuum in which much higher voltages can be used on the separation plates than in air. Additionally, the Lunar g1avity, only being 1/6 that of Earth, allows the particles more separation time between the plates and therefore enhances separation. For the separation studies, two lunar stimulants were used. The first simulant was created in-house, labeled KSC-1. using commercially supplied (sieved to 325 mesh) materials, and was composed of 40 wt. % feldspar ((Na,K,Ca)AlSi3O8;SiO2), 40 wt. % olivine ((Mg,Fe)2SiO4), 10 wt. % ilmenite (FeTiO3). and 10 wt. % spodumene (LiAlSi2O6) (pyroxene). The advantage of the in-house mixture is that the composition can he varied to simulate different soil compositions from different areas on the moon. This simulant was used to show proof-of-concept using the designed separator in air. The second stimulant was JSC-1. used for the vacuum experiments. JSC-1 is principally basalts, containing phases of plagioclase. pyroxene. olivine, and ilmenite. The JSC-1 was sieved to provide a 50-75 micron size range to correlate with the mean grain size found on the moon's surface [1]. Four different materials were investigated for the triboelectrification process; aluminum, copper. stainless steel, and PTFE. These materials were selected because they offer a wide variation in work functions (aluminum 4.28 eV, copper 4.65 eV. stainless steel 5.04 eV, and PTFE 5.75 eV). The difference between the work function of each material and the simulant influences the charge obtained by the grains. Each simulant was analyzed before and after separation using X-ray Photoelectron Spectroscopy (XPS) to determine mineral surface composition. In addition. Raman spectroscopy was performed on the JSC-1 before and after separation in vacuum to determine the mineral composition. Charge-to-mass (Q/M) measurements were performed using a fluidizing bed in air and passing the simulant through a static mixer of a particular material and collecting it in a Faraday pail grounded through an electrometer. To measure the Q/M in vacuum, a special device was constructed consisting of a heater/shaker cup that fed into a solid block of material (either PTFE, copper, or aluminum) in which a channel composed of a "zig-zag" series of inclines greater than 50 degrees has been cut. The voltage to the vibrating motor can be varied to control the amount of simulant passing through the channel. Figure I shows the Q/M measurements for JSC-1 tribocharged using the static mixers and the incline plane chargers in air, and the incline plane chargers in vacuum.

Advanced Electrode Materials for High Energy Next Generation Li ion Batteries

NASA Astrophysics Data System (ADS)

Hayner, Cary Michael

Lithium ion batteries are becoming an increasingly ubiquitous part of modern society. Since their commercial introduction by Sony in 1991, lithium-ion batteries have grown to be the most popular form of electrical energy storage for portable applications. Today, lithium-ion batteries power everything from cellphones and electric vehicles to e-cigarettes, satellites, and electric aircraft. Despite the commercialization of lithium-ion batteries over twenty years ago, it remains the most active field of energy storage research for its potential improvement over current technology. In order to capitalize on these opportunities, new materials with higher energy density and storage capacities must be developed. Unfortunately, most next-generation materials suffer from rapid capacity degradation or severe loss of capacity when rapidly discharged. In this dissertation, the development of novel anode and cathode materials for advanced high-energy and high-power lithium-ion batteries is reported. In particular, the application of graphene-based materials to stabilize active material is emphasized. Graphene, a unique two-dimensional material composed of atomically thin carbon sheets, has shown potential to address unsatisfactory rate capability, limited cycling performance and abrupt failure of these next-generation materials. This dissertation covers four major subjects: development of silicon-graphene composites, impact of carbon vacancies on graphene high-rate performance, iron fluoride-graphene composites, and ternary iron-manganese fluoride synthesis. Silicon is considered the most likely material to replace graphite as the anode active material for lithium-ion batteries due to its ability to alloy with large amounts of lithium, leading to significantly higher specific capacities than the graphite standard. However, Si also expands in size over 300% upon lithiation, leading to particle fracture and isolation from conductive support, resulting in cell failure within a few charge-discharge cycles. To stabilize silicon materials, composites of silicon nanoparticles were dispersed between graphene sheets and supported by a 3-D network of graphite formed by reconstituted regions of graphene stacks. These free-standing, self-supported composites exhibited excellent Li-ion storage capacities higher than 2200 mAh/g and good cycling stability. In order to improve the advantages graphene can provide as a 3-D scaffold, carbon vacancies were introduced into the basal planes via an acid-oxidation treatment. These vacancies markedly enhance the rate performance of graphene materials as well as silicon-graphene composites. Silicon-graphene composites containing carbon vacancies achieved high accessible storage capacities at fast charge/discharge rates that rival supercapacitor performance while maintaining good cycling stability. Optimal carbon vacancy size and density were determined. Graphene composites were also formed with iron trifluoride (FeF 3), a high-energy cathode material with ability to store up to 712 mAh/g capacity, over 3X more than current state-of-the-art cathode materials. A facile route that combines co-assembly and photothermal reduction was developed to synthesize free-standing, flexible FeF3/graphene papers. The papers contained a uniform dispersion of FeF3 nanoparticles (< 40 nm) and open ion diffusion channels in the porous, conducting network of graphene sheets that resulted in a flexible paper cathode with high charge storage capacity, rate, and cycling performance, without the need for other carbon additives or binder. Free-standing FeF3/graphene composites showed a high storage capacity of >400 mAh/g and improved cycling performance compared to bare FeF3 particles. Lastly, novel ternary iron-manganese fluoride (FexMn 1-xF2) cathode materials were synthesized via a convenient, bottom-up solution-phase synthesis which allowed control of particle size, shape, and surface morphology. The synthesized materials exhibited nanoscale features with average particle size of 20-40 nm. These ternary metal composites exhibited key, desirable properties for next-generation Li-ion battery cathode materials. The described process constituted a translatable route to large-scale production of ternary metal fluoride nanoparticles.

Degradation mechanism of polysaccharides on irradiated sugarcane bagasse

NASA Astrophysics Data System (ADS)

Ribeiro, M. A.; Oikawa, H.; Mori, M. N.; Napolitano, C. M.; Duarte, C. L.

2013-03-01

Sugarcane bagasse is composed of cellulose, hemicelluloses, lignin, and a minor amount of protein and inorganic materials. Cellulose consists of linear macromolecular chains of glucose, linked by β-1,4-glucosidic bonds between the number one and the number four carbon atoms of the adjacent glucose units. Hemicelluloses are heterogeneous polymers, unlike cellulose, and are usually composed of 50-200 monomer units of pentose such as xylose and arabinose. Lignin is a complex polymer of p-hydroxyphenylpropanoid units connected by CC and COC links. Radiation-induced reactions in the macromolecules of the cellulose materials are known to be initiated through fast distribution of the absorbed energy within the molecules to produce long- and short-lived radicals. The present study was carried out using sugarcane bagasse samples irradiated by a Radiation Dynamics electron beam accelerator with 1.5 MeV and 37 kW, with the objective to evaluate the cleavage of the polysaccharides and the by-products formed as a result of the absorbed dose. The electron beam processing in 30 kGy of absorbed dose changed the sugarcane bagasse structure and composition, causing some cellulose and hemicelluloses cleavage. These cleavages were partial, forming oligosaccharides and liberating the sugars glucose and arabinose. The main by-product was acetic acid, originated from the de-acetylating of hemicelluloses.

Combinatorial MAPLE deposition of antimicrobial orthopedic maps fabricated from chitosan and biomimetic apatite powders.

PubMed

Visan, A; Stan, G E; Ristoscu, C; Popescu-Pelin, G; Sopronyi, M; Besleaga, C; Luculescu, C; Chifiriuc, M C; Hussien, M D; Marsan, O; Kergourlay, E; Grossin, D; Brouillet, F; Mihailescu, I N

2016-09-10

Chitosan/biomimetic apatite thin films were grown in mild conditions of temperature and pressure by Combinatorial Matrix-Assisted Pulsed Laser Evaporation on Ti, Si or glass substrates. Compositional gradients were obtained by simultaneous laser vaporization of the two distinct material targets. A KrF* excimer (λ=248nm, τFWHM=25ns) laser source was used in all experiments. The nature and surface composition of deposited materials and the spatial distribution of constituents were studied by SEM, EDS, AFM, GIXRD, FTIR, micro-Raman, and XPS. The antimicrobial efficiency of the chitosan/biomimetic apatite layers against Staphylococcus aureus and Escherichia coli strains was interrogated by viable cell count assay. The obtained thin films were XRD amorphous and exhibited a morphology characteristic to the laser deposited structures composed of nanometric round shaped grains. The surface roughness has progressively increased with chitosan concentration. FTIR, EDS and XPS analyses indicated that the composition of the BmAp-CHT C-MAPLE composite films gradually modified from pure apatite to chitosan. The bioevaluation tests indicated that S. aureus biofilm is more susceptible to the action of chitosan-rich areas of the films, whilst the E. coli biofilm proved more sensible to areas containing less chitosan. The best compromise should therefore go, in our opinion, to zones with intermediate-to-high chitosan concentration which can assure a large spectrum of antimicrobial protection concomitantly with a significant enhancement of osseointegration, favored by the presence of biomimetic hydroxyapatite. Copyright © 2016 Elsevier B.V. All rights reserved.

Introducing catalyst in alkaline membrane for improved performance direct borohydride fuel cells

NASA Astrophysics Data System (ADS)

Qin, Haiying; Lin, Longxia; Chu, Wen; Jiang, Wei; He, Yan; Shi, Qiao; Deng, Yonghong; Ji, Zhenguo; Liu, Jiabin; Tao, Shanwen

2018-01-01

A catalytic material is introduced into the polymer matrix to prepare a novel polymeric alkaline electrolyte membrane (AEM) which simultaneously increases ionic conductivity, reduces the fuel cross-over. In this work, the hydroxide anion exchange membrane is mainly composed of poly(vinylalcohol) and alkaline exchange resin. CoCl2 is added into the poly(vinylalcohol) and alkaline exchange resin gel before casting the membrane to introduce catalytic materials. CoCl2 is converted into CoOOH after the reaction with KOH solution. The crystallinity of the polymer matrix decreases and the ionic conductivity of the composite membrane is notably improved by the introduction of Co-species. A direct borohydride fuel cell using the composite membrane exhibits an open circuit voltage of 1.11 V at 30 °C, which is notably higher than that of cells using other AEMs. The cell using the composite membrane achieves a maximum power density of 283 mW cm-2 at 60 °C while the cell using the membrane without Co-species only reaches 117 mW cm-2 at the same conditions. The outstanding performance of the cell using the composite membrane benefits from impregnation of the catalytic Co-species in the membrane, which not only increases the ionic conductivity but also reduces electrode polarization thus improves the fuel cell performance. This work provides a new approach to develop high-performance fuel cells through adding catalysts in the electrolyte membrane.

[Genetic improvement of breeding materials in tropical and sub- tropical maize].

PubMed

Sansern, Jampatong; Chaba, Jampatong

2011-12-01

In the present study, 122 maize local cultivars and adapted exotic germplasm from Thailand were used to develop open pollinate varieties (OPVs) using modified ear-to-row scheme, top-cross or test-cross programmes. Ten new maize OPVs with distinct characters were created based on the precise breeding objectives and directional design. The selection of breeding materials was based upon three factors: elite performance, broad adaptability, and genetic diversity. The synthesizing system provided four features: genetic mixing and recombination, equal comparable genetic contribution, mild selection pressure, and maximum intermating for genetic equilibrium (i.e., the female traits were close for the genetic com-positions). Subsequently, Suwan 1 composite and its deritives (Suwan 2, Suwan 3 composite, Suwan 5 and KS24 synthetics), KS6 and KS28 synthetics with the dent type of different origins, and Caripeno DMR composite, KS23, and KS27 synthetics with the dent type of Non-Suwan 1 origin were developed. These OPVs had been improved for 2~13 cycles using S1 recurrent selection method. About 50 inbred lines were developed from these OPVs, and 16 elite single (three-way) crosses were combined and released from these inbred lines. At present, at least one parental inbred line of all the tropical hybrids was derived from Suwan (KS) germplasm in Thailand. Based on the theory of the synthesizing OPVs and developing inbred lines, this paper discussed the genetic moderate diversity, relationship, heterotic group, and patterns for synthesizing OPVs, and inspiration for composed OPVs to heterosis breeding.

A verification strategy for web services composition using enhanced stacked automata model.

PubMed

Nagamouttou, Danapaquiame; Egambaram, Ilavarasan; Krishnan, Muthumanickam; Narasingam, Poonkuzhali

2015-01-01

Currently, Service-Oriented Architecture (SOA) is becoming the most popular software architecture of contemporary enterprise applications, and one crucial technique of its implementation is web services. Individual service offered by some service providers may symbolize limited business functionality; however, by composing individual services from different service providers, a composite service describing the intact business process of an enterprise can be made. Many new standards have been defined to decipher web service composition problem namely Business Process Execution Language (BPEL). BPEL provides an initial work for forming an Extended Markup Language (XML) specification language for defining and implementing business practice workflows for web services. The problems with most realistic approaches to service composition are the verification of composed web services. It has to depend on formal verification method to ensure the correctness of composed services. A few research works has been carried out in the literature survey for verification of web services for deterministic system. Moreover the existing models did not address the verification properties like dead transition, deadlock, reachability and safetyness. In this paper, a new model to verify the composed web services using Enhanced Stacked Automata Model (ESAM) has been proposed. The correctness properties of the non-deterministic system have been evaluated based on the properties like dead transition, deadlock, safetyness, liveness and reachability. Initially web services are composed using Business Process Execution Language for Web Service (BPEL4WS) and it is converted into ESAM (combination of Muller Automata (MA) and Push Down Automata (PDA)) and it is transformed into Promela language, an input language for Simple ProMeLa Interpreter (SPIN) tool. The model is verified using SPIN tool and the results revealed better recital in terms of finding dead transition and deadlock in contrast to the existing models.

Composition, Alteration, and Texture of Fault-Related Rocks from Safod Core and Surface Outcrop Analogs: Evidence for Deformation Processes and Fluid-Rock Interactions

NASA Astrophysics Data System (ADS)

Bradbury, Kelly K.; Davis, Colter R.; Shervais, John W.; Janecke, Susanne U.; Evans, James P.

2015-05-01

We examine the fine-scale variations in mineralogical composition, geochemical alteration, and texture of the fault-related rocks from the Phase 3 whole-rock core sampled between 3,187.4 and 3,301.4 m measured depth within the San Andreas Fault Observatory at Depth (SAFOD) borehole near Parkfield, California. This work provides insight into the physical and chemical properties, structural architecture, and fluid-rock interactions associated with the actively deforming traces of the San Andreas Fault zone at depth. Exhumed outcrops within the SAF system comprised of serpentinite-bearing protolith are examined for comparison at San Simeon, Goat Rock State Park, and Nelson Creek, California. In the Phase 3 SAFOD drillcore samples, the fault-related rocks consist of multiple juxtaposed lenses of sheared, foliated siltstone and shale with block-in-matrix fabric, black cataclasite to ultracataclasite, and sheared serpentinite-bearing, finely foliated fault gouge. Meters-wide zones of sheared rock and fault gouge correlate to the sites of active borehole casing deformation and are characterized by scaly clay fabric with multiple discrete slip surfaces or anastomosing shear zones that surround conglobulated or rounded clasts of compacted clay and/or serpentinite. The fine gouge matrix is composed of Mg-rich clays and serpentine minerals (saponite ± palygorskite, and lizardite ± chrysotile). Whole-rock geochemistry data show increases in Fe-, Mg-, Ni-, and Cr-oxides and hydroxides, Fe-sulfides, and C-rich material, with a total organic content of >1 % locally in the fault-related rocks. The faults sampled in the field are composed of meters-thick zones of cohesive to non-cohesive, serpentinite-bearing foliated clay gouge and black fine-grained fault rock derived from sheared Franciscan Formation or serpentinized Coast Range Ophiolite. X-ray diffraction of outcrop samples shows that the foliated clay gouge is composed primarily of saponite and serpentinite, with localized increases in Ni- and Cr-oxides and C-rich material over several meters. Mesoscopic and microscopic textures and deformation mechanisms interpreted from the outcrop sites are remarkably similar to those observed in the SAFOD core. Micro-scale to meso-scale fabrics observed in the SAFOD core exhibit textural characteristics that are common in deformed serpentinites and are often attributed to aseismic deformation with episodic seismic slip. The mineralogy and whole-rock geochemistry results indicate that the fault zone experienced transient fluid-rock interactions with fluids of varying chemical composition, including evidence for highly reducing, hydrocarbon-bearing fluids.

Production of Metal-Free Composites Composed of Graphite Oxide and Oxidized Carbon Nitride Nanodots and Their Enhanced Photocatalytic Performances.

PubMed

Kim, Seung Yeon; Oh, Junghoon; Park, Sunghee; Shim, Yeonjun; Park, Sungjin

2016-04-04

A novel metal-free composite (GN) composed of two types of carbon-based nanomaterials, graphite oxide (GO) and 2D oxidized carbon nitride (OCN) nanodots was produced. Chemical and morphological characterizations reveal that GN contains a main component of GO with well-dispersed 2D OCN nanodots. GN shows enhanced photocatalytic performance for degrading an organic pollutant, Rhodamine B, under visible light. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aeolian bedforms, yardangs, and indurated surfaces in the Tharsis Montes as seen by the HiRISE Camera: Evidence for dust aggregates

USGS Publications Warehouse

Bridges, N.T.; Banks, M.E.; Beyer, R.A.; Chuang, F.C.; Noe Dobrea, E.Z.; Herkenhoff, K. E.; Keszthelyi, L.P.; Fishbaugh, K.E.; McEwen, A.S.; Michaels, T.I.; Thomson, B.J.; Wray, J.J.

2010-01-01

HiRISE images of Mars with ground sampling down to 25 cm/pixel show that the dust-rich mantle covering the surfaces of the Tharsis Montes is organized into ridges whose form and distribution are consistent with formation by aeolian saltation. Other dusty areas near the volcanoes and elsewhere on the planet exhibit a similar morphology. The material composing these "reticulate" bedforms is constrained by their remote sensing properties and the threshold curve combined with the saltation/suspension boundary, both of which vary as a function of elevation (atmospheric pressure), particle size, and particle composition. Considering all of these factors, dust aggregates are the most likely material composing these bedforms. We propose that airfall dust on and near the volcanoes aggregates in situ over time, maybe due to electrostatic charging followed by cementation by salts. The aggregates eventually reach a particle size at which saltation is possible. Aggregates on the flanks are transported downslope by katabatic winds and form linear and "accordion" morphologies. Materials within the calderas and other depressions remain trapped and are subjected to multidirectional winds, forming an interlinked "honeycomb" texture. In many places on and near the volcanoes, light-toned, low thermal inertia yardangs and indurated surfaces are present. These may represent "duststone" formed when aggregates reach a particle size below the threshold curve, such that they become stabilized and subsequently undergo cementation. ?? 2009 Elsevier Inc.

Wood composites

Treesearch

Lars Berglund; Roger M. Rowell

2005-01-01

A composite can be defined as two or more elements held together by a matrix. By this definition, what we call “solid wood” is a composite. Solid wood is a three-dimensional composite composed of cellulose, hemicelluloses and lignin (with smaller amounts of inorganics and extractives), held together by a lignin matrix. The advantages of developing wood composites are (...

Thickness ratio effects on quasistatic actuation and sensing behavior of laminate magnetoelectric cantilevers

NASA Astrophysics Data System (ADS)

Wang, Yezuo; Atulasimha, Jayasimha; Clarke, Joshua; Sundaresan, Vishnu B.

2010-04-01

In this work, the magnetoelectric cantilever composed of a layer of Galfenol and a layer of PZT-5H is studied for novel applications such as surgical ablation tools and cutting tools for machining applications. For developing a suitable model for the magnetoelectric cantilever, an energy based approach for the non-linear constitutive behavior of the magnetostrictive material and linear piezoelectric constitutive equations will be coupled with Euler Bernoulli model for composite beams. The cantilever is held in a uniform magnetic field and the magnetic field is measured by a Gaussmeter. The tip-deflection of the cantilever is detected by a laser triangulation sensor. The piezoelectric response can be studied with low noise preamplifier. Four PZT-5H layers with different thickness are separately bonded on the top of the same Galfenol layer and characterized to study the thickness ratio effects on the quasistatic actuation and sensing behavior of the composite cantilever.

Apollo 16 impact-melt splashes - Petrography and major-element composition

NASA Technical Reports Server (NTRS)

See, Thomas H.; Horz, Friedrich; Morris, Richard V.

1986-01-01

Petrographic and major-element analyses are applied to 50 Apollo 16 impact-melt splash (IMS) samples in order to determine their origin and assess the nature of the subregolith source. The macroscopic analyses reveal that the IMSs exhibit a glassy appearance, but the textures range from holohyaline to hyalopilitic. Schlieren-rich glasses dominate the holohyaline areas, and the crystalline areas are mainly spherulitic. It is observed that most IMSs contain feldspathic monomineralic and lithic clasts and no regolithic materials. It is detected that the chemistry of most IMSs is not like the local regolith and appears to represent varied mixtures of VHA impact-melt breccias and anorthosite; the host rocks are mainly dimict breccias. It is concluded that the Cayley Formation is a polymict deposit composed of VHA impact-melt breccias and anorthosites. Tables revealing the macroscopic characteristics of the IMSs and the major-element composition of IMSs and various host rock are presented.

Imaging and Laser Spectroscopy Investigation of Insect Wings

NASA Astrophysics Data System (ADS)

Shiver, Tegan; Lawhead, Carlos; Anderson, Josiah; Cooper, Nathan; Ujj, Laszlo; Pall Life Sciences Collaboration

2014-03-01

Measuring the surface morphology and chemical composition of insect wings is important to understand the extreme mechanical properties and the biophysical functionalities of the wings. We have measured the image of the membrane of the cicada (genus Tibicen) wing with the help of Scanning Electron Microscopy (SEM). The results confirm the existing periodic structure of the wing measured previously. The SEM imaging can be used to measure the surface morphology of any insect species wings. The physical surface structure of the cicada wing is an example of a new class of biomaterials that can kill bacteria on contact. In order to identify the chemical composition of the wing, we have measured the vibrational spectra of the wing's membrane (Raman and CARS). The measured spectra are consistent with the original assumption that the wing membrane is composed of protein, wax, and chitin. The results of these studies can be used to make artificial materials in the future.

Composing Texts, Composing Lives.

ERIC Educational Resources Information Center

Perl, Sondra

1994-01-01

Using composition, reader response, critical, and feminist theories, a teacher demonstrates how adult students respond critically to literary texts and how teachers must critically analyze the texts of their teaching practice. Both students and teachers can use writing to bring their experiences to interpretation. (SK)

Nitrogen and Fluorine-Codoped Carbon Nanowire Aerogels as Metal-Free Electrocatalysts for Oxygen Reduction Reaction

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

Fu, Shaofang; Zhu, Chengzhou; Song, Junhua

2017-07-11

The development of active, durable, and low-cost catalysts to replace noble metal-based materials is highly desirable to promote the sluggish oxygen reduction reaction in fuel cells. Herein, nitrogen and fluorine-codoped three-dimensional carbon nanowire aerogels, composed of interconnected carbon nanowires, were synthesized for the first time by a hydrothermal carbonization process. Owing to their porous nanostructures and heteroatom-doping, the as-prepared carbon nanowire aerogels, with optimized composition, present excellent electrocatalytic activity that is comparable to commercial Pt/C. Remarkably, the aerogels also exhibit superior stability and methanol tolerance. This synthesis procedure paves a new way to design novel heteroatomdoped catalysts.

The planet Mars - From antiquity to the present

NASA Astrophysics Data System (ADS)

Kieffer, Hugh H.; Jakosky, Bruce M.; Snyder, Conway W.

Telescopic observations of Mars, from those of Galileo in 1610 to the late 19th century, were summarized by Flammarion (1892, 1909). Major compilations of knowledge of Mars were produced by Antoniadi (1930) and de Vaucouleurs (1954). Polar cap composition was debated until the discovery by the Viking mission that the north and south perennial polar caps are composed of different materials. Spacecraft data indicate a rich and diverse geologic history as well as many unsolved puzzles. An annotated list of books about Mars is provided. Basic physical and chemical data on Mars are summarized in tabular form, and a guide to the Martian seasons is given.

Self-Assembly Behavior of Pullulan Abietate

NASA Astrophysics Data System (ADS)

Gradwell, Sheila; Esker, Alan; Glasser, Wolgang; Heinze, Thomas

2003-03-01

Wood is one of nature's most fascinating biological composites due to its toughness and resistance to fracture properties. These properties stem from the self-assembly of cellulose microfibrils in an amorphous matrix of hemicellulose and lignin. In recent years, science has looked to nature for guidance in preparing synthetic materials with desirable physical properties. In order to study the self-assembly process in wood, a model system composed of a polysaccharide, pullulan abietate, and a biomimetic cellulose substrate prepared by the Langmuir-Blodgett technique has been developed. Interfacial tension and surface plasmon resonance measurements used to study the self-assembly process will be discussed for different pullulan derivatives.

Spectroscopic thermoacoustic imaging of water and fat composition

NASA Astrophysics Data System (ADS)

Bauer, Daniel R.; Wang, Xiong; Vollin, Jeff; Xin, Hao; Witte, Russell S.

2012-07-01

During clinical studies, thermoacoustic imaging (TAI) failed to reliably identify malignant breast tissue. To increase detection capability, we propose spectroscopic TAI to differentiate samples based on the slope of their dielectric absorption. Phantoms composed of different ratios of water and fat were imaged using excitation frequencies between 2.7 and 3.1 GHz. The frequency-dependent slope of the TA signal was highly correlated with that of its absorption coefficient (R2 = 0.98 and p < 0.01), indicating spectroscopic TAI can distinguish materials based on their intrinsic dielectric properties. This approach potentially enhances cancer detection due to the increased water content of many tumors.

Semiconductor laser insert with uniform illumination for use in photodynamic therapy

NASA Astrophysics Data System (ADS)

Charamisinau, Ivan; Happawana, Gemunu; Evans, Gary; Rosen, Arye; Hsi, Richard A.; Bour, David

2005-08-01

A low-cost semiconductor red laser light delivery system for esophagus cancer treatment is presented. The system is small enough for insertion into the patient's body. Scattering elements with nanoscale particles are used to achieve uniform illumination. The scattering element optimization calculations, with Mie theory, provide scattering and absorption efficiency factors for scattering particles composed of various materials. The possibility of using randomly deformed spheres and composite particles instead of perfect spheres is analyzed using an extension to Mie theory. The measured radiation pattern from a prototype light delivery system fabricated using these design criteria shows reasonable agreement with the theoretically predicted pattern.

Thin film lithium-based batteries and electrochromic devices fabricated with nanocomposite electrode materials

DOEpatents

Gillaspie, Dane T; Lee, Se-Hee; Tracy, C. Edwin; Pitts, John Roland

2014-02-04

Thin-film lithium-based batteries and electrochromic devices (10) are fabricated with positive electrodes (12) comprising a nanocomposite material composed of lithiated metal oxide nanoparticles (40) dispersed in a matrix composed of lithium tungsten oxide.

Caracterisation de l'effet du vieillissement en milieu aqueux sur les proprietes mecaniques de composites a matrice elastomere

NASA Astrophysics Data System (ADS)

Favre, Audrey

Rubber composites are widely used in several engineering fields, such as automotive, and more recently for inflatable dams and other innovative underwater applications. These rubber materials are composed by an elastomeric matrix while the reinforcing phase is a synthetic fabric. Since these components are expected to operate several years in water environment, their durability must be guaranteed. The use of rubber materials immersed in water is not new, in fact, these materials have been studied for almost one century. However, the knowledge on reinforced rubber composites immersed several years in water is still limited. In this work, investigations on reinforced rubbers were carried out in the framework of a research project in partnership with Alstom and Hydro-Quebec. The objective of this study was to identify rubber composites that could be used under water for long periods. Various rubber composites with ethylene-propylene-diene monomer (EPDM), silicone, EPDM/silicone and polychloroprene (Neoprene) matrices reinforced with E-glass fabric were studied. Thus, these materials were exposed to an accelerated ageing at 85 °C underwater for periods varying from 14 to 365 days. For comparison purposes, they were also immersed and aged one year at room temperature (21 °C). The impact of accelerated aging was estimated through three different characterization methods. Scanning electron microscopy (SEM) was first used to assess the quality of fiber-matrix interface. Then, water absorption tests were performed to quantify the rate of water absorption during immersion. Finally the evolution of the mechanical properties was followed by the determination of Young's modulus (E) and ultimate stress (sigmau) using a dedicated traction test. This analysis allowed to point out that the quality of the fiber-matrix interface was the main factor influencing the drop of the mechanical properties and their durability. Moreover, it was noticed that this interface could be improved by using appropriate coupling agent as confirmed by the silicone composite with treated fabric. It was also observed that fiber-matrix interface could be a place where high stresses were localized because of differential swelling leading to an important loss of mechanical properties. The results revealed very different behaviors from one composite to another. The accelerated aging of EPDM/silicone and Neoprene composites led to a rapid diminution of mechanical properties in only 14 days. Conversely, silicone composites showed a 20 % increase of mechanical properties after 75 days of immersion. EPDM composites exhibited an important variability from one sample to another. It can be concluded from this study that composites made from silicone matrix with treated E-glass result in a better durability underwater. Keywords: composite elastomer, accelerated ageing, immersion in the water

Synergistic Enhancement of Electrocatalytic CO 2 Reduction with Gold Nanoparticles Embedded in Functional Graphene Nanoribbon Composite Electrodes

DOE PAGES

Rogers, Cameron; Perkins, Wade S.; Veber, Gregory; ...

2017-02-24

Regulating the complex environment accounting for the stability, selectivity, and activity of catalytic metal nanoparticle interfaces represents a challenge to heterogeneous catalyst design. Here in this paper, we demonstrate the intrinsic performance enhancement of a composite material composed of gold nanoparticles (AuNPs) embedded in a bottom-up synthesized graphene nanoribbon (GNR) matrix for the electrocatalytic reduction of CO 2. Electrochemical studies reveal that the structural and electronic properties of the GNR composite matrix increase the AuNP electrochemically active surface area (ECSA), lower the requisite CO 2 reduction overpotential by hundreds of millivolts (catalytic onset > -0.2 V versus reversible hydrogen electrodemore » (RHE)), increase the Faraday efficiency (>90%), markedly improve stability (catalytic performance sustained over >24 h), and increase the total catalytic output (>100-fold improvement over traditional amorphous carbon AuNP supports). The inherent structural and electronic tunability of bottom-up synthesized GNR-AuNP composites affords an unrivaled degree of control over the catalytic environment, providing a means for such profound effects as shifting the rate-determining step in the electrocatalytic reduction of CO 2 to CO, and thereby altering the electrocatalytic mechanism at the nanoparticle surface.« less

Graphene-poly(vinyl alcohol) composites: Fabrication, adsorption and electrochemical properties

NASA Astrophysics Data System (ADS)

Wang, Ning; Chang, Peter R.; Zheng, Pengwu; Ma, Xiaofei

2014-09-01

Porous composites of graphene oxide (GO)-poly(vinyl alcohol) (PVA) were fabricated using a process of aqueous suspension precursor freezing, solvent exchange, and ethanol drying. When frozen, ice crystals formed leaving a porous structure, composed of randomly oriented GO sheets consolidated by PVA. The yellow GO-PVA composite could be reduced with glucose to obtain a black porous RGO (PRGO). XRD revealed that PVA enlarged the GO interlay spacing in the GO-PVA composite, and that RGO sheets were highly disordered in single or several layers in PRGO. GO-PVA and PRGO exhibited ultralight densities of 10.52 and 11.42 mg/cm3, respectively. GO-PVA adsorbed greater quantities of water, ethanol, and soybean oil than PRGO. The methylene blue (MB) adsorption pattern for both materials was also investigated. The kinetic adsorption and isotherm data fit the pseudo second-order and the Langmuir models, respectively. The maximum adsorption capacity according to the Langmuir isotherm model was 571.4 mg/g for GO-PVA. The electrochemical properties of PRGO were estimated using cyclic voltammetry, electrochemical impedance spectrometry, and chronopotentiometry. The PRGO electrode exhibited large capacitance (82.8 F/g) and small internal resistance (0.52 Ω).

General Synthetic Strategy for Libraries of Supported Multicomponent Metal Nanoparticles.

PubMed

Yang, Hui; Bradley, Siobhan J; Wu, Xin; Chan, Andrew; Waterhouse, Geoffrey I N; Nann, Thomas; Zhang, Jian; Kruger, Paul E; Ma, Shengqian; Telfer, Shane G

2018-04-18

Nanoparticles comprising three or more different metals are challenging to prepare. General methods that tackle this challenge are highly sought after as multicomponent metal nanoparticles display favorable properties in applications such as catalysis, biomedicine, and imaging. Herein, we report a practical and versatile approach for the synthesis of nanoparticles composed of up to four different metals. This method relies on the thermal decomposition of nanostructured composite materials assembled from platinum nanoparticles, a metal-organic framework (ZIF-8), and a tannic acid coordination polymer. The controlled integration of multiple metal cations (Ni, Co, Cu, Mn, Fe, and/or Tb) into the tannic acid shell of the precursor material dictates the composition of the final multicomponent metal nanoparticles. Upon thermolysis, the platinum nanoparticles seed the growth of the multicomponent metal nanoparticles via coalescence with the metallic constituents of the tannic acid coordination polymer. The nanoparticles are supported in the walls of hollow nitrogen-doped porous carbon capsules created by the decomposition of the organic components of the precursor. The capsules prevent sintering and detachment of the nanoparticles, and their porosity allows for efficient mass transport. To demonstrate the utility of producing a broad library of supported multicomponent metal nanoparticles, we tested their electrocatalytic performance toward the hydrogen evolution reaction and oxygen evolution reaction. We discovered functional relationships between the composition of the nanoparticles and their electrochemical activity and identified the PtNiCu and PtNiCuFe nanoparticles as particularly efficient catalysts. This highlights how to generate diverse libraries of multicomponent metal nanoparticles that can be synthesized and subsequently screened to identify high-performance materials for target applications.

Thermomechanical Formation–Structure–Property Relationships in Photopolymerized Copper-Catalyzed Azide–Alkyne (CuAAC) Networks

PubMed Central

Baranek, Austin; Song, Han Byul; McBride, Mathew; Finnegan, Patricia; Bowman, Christopher N.

2016-01-01

Bulk photopolymerization of a library of synthesized multifunctional azides and alkynes was carried out toward developing structure–property relationships for CuAAC-based polymer networks. Multifunctional azides and alkynes were formulated with a copper catalyst and a photoinitiator, cured, and analyzed for their mechanical properties. Material properties such as the glass transition temperatures (Tg) show a strong dependence on monomer structure with Tg values ranging from 41 to 90 °C for the series of CuAAC monomers synthesized in this study. Compared to the triazoles, analogous thioether-based polymer networks exhibit a 45–49 °C lower Tg whereas analogous monomers composed of ethers in place of carbamates exhibit a 40 °C lower Tg. Here, the formation of the triazole moiety during the polymerization represents a critical component in dictating the material properties of the ultimate polymer network where material properties such as the rubbery modulus, cross-link density, and Tg all exhibit strong dependence on polymerization conversion, monomer composition, and structure postgelation. PMID:27867223

Templated Assembly of a Functional Ordered Protein Macromolecular Framework from P22 Virus-like Particles.

PubMed

McCoy, Kimberly; Uchida, Masaki; Lee, Byeongdu; Douglas, Trevor

2018-04-24

Bottom-up construction of mesoscale materials using biologically derived nanoscale building blocks enables engineering of desired physical properties using green production methods. Virus-like particles (VLPs) are exceptional building blocks due to their monodispersed sizes, geometric shapes, production ease, proteinaceous composition, and our ability to independently functionalize the interior and exterior interfaces. Here a VLP, derived from bacteriophage P22, is used as a building block for the fabrication of a protein macromolecular framework (PMF), a tightly linked 3D network of functional protein cages that exhibit long-range order and catalytic activity. Assembly of PMFs was electrostatically templated, using amine-terminated dendrimers, then locked into place with a ditopic cementing protein that binds to P22. Long-range order is preserved on removal of the dendrimer, leaving a framework material composed completely of protein. Encapsulation of β-glucosidase enzymes inside of P22 VLPs results in formation of stable, condensed-phase materials with high local concentration of enzymes generating catalytically active PMFs.

Application of spouted bed elutriation in the recycling of lithium ion batteries

NASA Astrophysics Data System (ADS)

Bertuol, Daniel A.; Toniasso, Camila; Jiménez, Bernardo M.; Meili, Lucas; Dotto, Guilherme L.; Tanabe, Eduardo H.; Aguiar, Mônica L.

2015-02-01

The growing environmental concern, associated with the continuous increase in electronic equipment production, has induced the development of new technologies to recycle the large number of spent batteries generated in recent years. The amount of spent lithium-ion batteries (LIBs) tends to grow over the next years. These batteries are composed by valuable metals, such as Li, Co, Cu and Al, which can be recovered. Thus, the present work is carried out in two main steps: In the first step, a characterization of the LIBs is performed. Batteries from different brands and models are dismantled and their components characterized regarding to the chemical composition and main phases. In the second step, a sample of LIBs is shredded and the different materials present are separated by spouted bed elutriation. The results show that spouted bed elutriation is a simple and inexpensive way to obtain the separation of the different materials (polymers, metals, active electrode materials) present in spent LIBs.

Radiopacity and cytotoxicity of Portland cement associated with niobium oxide micro and nanoparticles

PubMed Central

MESTIERI, Leticia Boldrin; TANOMARU-FILHO, Mário; GOMES-CORNÉLIO, Ana Livia; SALLES, Loise Pedrosa; BERNARDI, Maria Inês Basso; GUERREIRO-TANOMARU, Juliane Maria

2014-01-01

Objective Mineral Trioxide Aggregate (MTA) is composed of Portland Cement (PC) and bismuth oxide (BO). Replacing BO for niobium oxide (NbO) microparticles (Nbµ) or nanoparticles (Nbη) may improve radiopacity and bioactivity. The aim of this study was to evaluate the radiopacity and cytotoxicity of the materials: 1) PC; 2) White MTA; 3) PC+30% Nbµ; 4) PC+30% Nbη. Material and Methods For the radiopacity test, specimens of the different materials were radiographed along an aluminum step-wedge. For cell culture assays, Saos-2 osteoblastic-cells (ATCC HTB-85) were used. Cell viability was evaluated through MTT assay, and bioactivity was assessed by alkaline phosphatase activity assay. Results The results demonstrated higher radiopacity for MTA, followed by Nbµ and Nbη, which had similar values. Cell culture analysis showed that PC and PC+NbO associations promoted greater cell viability than MTA. Conclusions It was concluded that the combination of PC+NbO is a potential alternative for composition of MTA. PMID:25591023

Genetic Relationships Between Chondrules, Rims and Matrix

NASA Technical Reports Server (NTRS)

Huss, G. R.; Alexander, C. M. OD.; Palme, H.; Bland, P. A.; Wasson, J. T.

2004-01-01

The most primitive chondrites are composed of chondrules and chondrule fragments, various types of inclusions, discrete mineral grains, metal, sulfides, and fine-grained materials that occur as interchondrule matrix and as chondrule/inclusion rims. Understanding how these components are related is essential for understanding how chondrites and their constituents formed and were processed in the solar nebula. For example, were the first generations of chondrules formed by melting of matrix or matrix precursors? Did chondrule formation result in appreciable transfer of chondrule material into the matrix? Here, we consider three types of data: 1) compositional data for bulk chondrites and matrix, 2) mineralogical and textural information, and 3) the abundances and characteristics of presolar materials that reside in the matrix and rims. We use these data to evaluate the roles of evaporation and condensation, chondrule formation, mixing of different nebular components, and secondary processing both in the nebula and on the parent bodies. Our goal is to identify the things that are reasonably well established and to point out the areas that need additional work.

Biphase-Interface Enhanced Sodium Storage and Accelerated Charge Transfer: Flower-Like Anatase/Bronze TiO2/C as an Advanced Anode Material for Na-Ion Batteries.

PubMed

Chu, Chenxiao; Yang, Jing; Zhang, Qianqian; Wang, Nana; Niu, Feier; Xu, Xuena; Yang, Jian; Fan, Weiliu; Qian, Yitai

2017-12-20

Flower-like assembly of ultrathin nanosheets composed of anatase and bronze TiO 2 embedded in carbon is successfully synthesized by a simple solvothermal reaction, followed with a high-temperature annealing. As an anode material in sodium-ion batteries, this composite exhibits outstanding electrochemical performances. It delivers a reversible capacity of 120 mA h g -1 over 6000 cycles at 10 C. Even at 100 C, there is still a capacity of 104 mA h g -1 . Besides carbon matrix and hierarchical structure, abundant interfaces between anatase and bronze greatly enhance the performance by offering additional sites for reversible Na + storage and improving the charge-transfer kinetics. The interface enhancements are confirmed by discharge/charge profiles, rate performances, electrochemical impedance spectra, and first-principle calculations. These results offer a new pathway to upgrade the performances of anode materials in sodium-ion batteries.

Flight and ground tests of a very low density elastomeric ablative material

NASA Technical Reports Server (NTRS)

Olsen, G. C.; Chapman, A. J., III

1972-01-01

A very low density ablative material, a silicone-phenolic composite, was flight tested on a recoverable spacecraft launched by a Pacemaker vehicle system; and, in addition, it was tested in an arc heated wind tunnel at three conditions which encompassed most of the reentry heating conditions of the flight tests. The material was composed, by weight, of 71 percent phenolic spheres, 22.8 percent silicone resin, 2.2 percent catalyst, and 4 percent silica fibers. The tests were conducted to evaluate the ablator performance in both arc tunnel and flight tests and to determine the predictability of the albator performance by using computed results from an existing one-dimensional numerical analysis. The flight tested ablator experienced only moderate surface recession and retained a smooth surface except for isolated areas where the char was completely removed, probably following reentry and prior to or during recovery. Analytical results show good agreement between arc tunnel and flight test results. The thermophysical properties used in the analysis are tabulated.

Experimental and theoretical description of the optical properties of Myrcia sylvatica essential oil.

PubMed

Silva Prado, Andriele da; Leal, Luciano Almeida; de Brito, Patrick Pascoal; de Almeida Fonseca, Antonio Luciano; Blawid, Stefan; Ceschin, Artemis Marti; Veras Mourão, Rosa Helena; da Silva Júnior, Antônio Quaresma; Antonio da Silva Filho, Demétrio; Ribeiro Junior, Luiz Antonio; Ferreira da Cunha, Wiliam

2017-07-01

We present an extensive study of the optical properties of Myrcia sylvatica essential oil with the goal of investigating the suitability of its material system for uses in organic photovoltaics. The methods of extraction, experimental analysis, and theoretical modeling are described in detail. The precise composition of the oil in our samples is determined via gas chromatography, mass spectrometry, and X-ray scattering techniques. The measurements indicate that, indeed, the material system of Myrcia sylvatica essential oil may be successfully employed for the design of organic photovoltaic devices. The optical absorption of the molecules that compose the oil are calculated using time-dependent density functional theory and used to explain the measured UV-Vis spectra of the oil. We show that it is sufficient to consider the α-bisabolol/cadalene pair, two of the main constituents of the oil, to obtain the main features of the UV-Vis spectra. This finding is of importance for future works that aim to use Myrcia sylvatica essential oil as a photovoltaic material.

Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses.

PubMed

Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C; Altman, Sidney; Schwarz, Udo D; Kyriakides, Themis R; Schroers, Jan

2016-05-27

Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design.

Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses

NASA Astrophysics Data System (ADS)

Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B. Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C.; Altman, Sidney; Schwarz, Udo D.; Kyriakides, Themis R.; Schroers, Jan

2016-05-01

Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design.

All Biomass and UV Protective Composite Composed of Compatibilized Lignin and Poly (Lactic-acid)

NASA Astrophysics Data System (ADS)

Kim, Youngjun; Suhr, Jonghwan; Seo, Hee-Won; Sun, Hanna; Kim, Sanghoon; Park, In-Kyung; Kim, Soo-Hyun; Lee, Youngkwan; Kim, Kwang-Jin; Nam, Jae-Do

2017-03-01

Utilization of carbon-neutral biomass became increasingly important due to a desperate need for carbon reduction in the issue of global warming in light of replacing petroleum-based materials. We used lignin, which was an abundant, low cost, and non-food based biomass, for the development of all biomass-based films and composites through reactive compatibilization with poly (lactic-acid) (PLA). Using a facile and practical route, the hydrophilic hydroxyl groups of lignin were acetylated to impose the compatibility with PLA. The solubility parameter of the pristine lignin at 26.3 (J/cm3)0.5 was altered to 20.9 (J/cm3)0.5 by acetylation allowing the good compatibility with PLA at 20.2 (J/cm3)0.5. The improved compatibility of lignin and PLA provided substantially decreased lignin domain size in composites (12.7 μm), which subsequently gave transparent and UV-protection films (visual transmittance at 76% and UV protection factor over 40). The tensile strength and elongation of the developed composite films were increased by 22% and 76%, respectively, and the biobased carbon content was confirmed as 96 ± 3%. The developed PLA/lignin composites provided 100% all-biomass contents and balanced optical and mechanical properties that could broaden its eco-friendly applications in various industries.

Improved conversion of herbaceous biomass to biofuels: Potential for modification of key plant characteristics

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

Sladden, S.E.; Bransby, D.I.

1989-10-01

Biomass crops are converted to fuels via biochemical and thermochemical processes. The process preferred depends on properties and cost of available feedstocks, and on the specific products desired. Since most mature biomass crops are composed of up to 80% cell wall fibers, the properties of these fibers determine, to a large degree, the conversion potential of the crop. However, biomass crops also contain small amounts of proteins, soluble carbohydrates and interfering materials (e.g., tannins and silica) which also influence the desirability of the feedstock in specific conversion processes. Fortunately, wide variation exists in the chemical composition of potential biomass crops.more » Although the chemical composition of feedstocks can be influenced significantly with judicious management has species selection, some traits are sufficiently heritable to permit breeding for improved feedstock composition. In addition to breeding for specific compositional traits directly, selection for in vitro digestibility or for easily-measured canopy or physiological traits may lead to more rapid and efficient progress in feedstock improvement, provided those measurements are highly-correlated with desirable feedstock composition. At the same time breeders must improve, or at least avoid damaging, stand longevity, tendency of plants to lodge, and establishment traits (e.g., disease resistance and seedling vigor). 46 refs., 8 tabs.« less

Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses

PubMed Central

Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B. Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C.; Altman, Sidney; Schwarz, Udo D.; Kyriakides, Themis R.; Schroers, Jan

2016-01-01

Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design. PMID:27230692

Flower-like In2O3 modified by reduced graphene oxide sheets serving as a highly sensitive gas sensor for trace NO2 detection.

PubMed

Liu, Jie; Li, Shan; Zhang, Bo; Wang, Yinglin; Gao, Yuan; Liang, Xishuang; Wang, Yue; Lu, Geyu

2017-10-15

In this work, we described gas sensors based on the materials composed of hierarchical flower-likeIn 2 O 3 and reduced graphene oxide (rGO), which were fabricated by a facile one-step hydrothermal method. The rGO-In 2 O 3 composites exhibited enhanced sensing performance towards NO 2 through comparison with the pure In 2 O 3 sample. The operating temperature can be tuned by the percentage of rGO in the composites. The sensor based on 5wt% rGO-In 2 O 3 could work at room temperature with a high response value to 1ppm NO 2 . 3wt% rGO-In 2 O 3 composite was adopted for the ultra-sensitivity gas sensor owing to its extremely low limit of detection of 10ppb with rapid response time to NO 2 . The sensor also exhibited excellent selectivity and stability. The ultra-sensitivity of rGO-In 2 O 3 should be related to synergistic effect of the hierarchical structure of In 2 O 3 and the presence of rGO in the composites, which provided enhanced surface area and local p-n heterojunctions in rGO/In 2 O 3 composites. Copyright © 2017 Elsevier Inc. All rights reserved.

Chemical precursors to non-oxide ceramics: Macro to nanoscale materials

NASA Astrophysics Data System (ADS)

Forsthoefel, Kersten M.

Non-oxide ceramics exhibit a number of important properties that make them ideal for technologically important applications (thermal and chemical stability, high strength and hardness, wear-resistance, light weight, and a range of electronic and optical properties). Unfortunately, traditional methodologies to these types of materials are limited to fairly simple shapes and complex processed forms cannot be attained through these methods. The establishment of the polymeric precursor approach has allowed for the generation of advanced materials, such as refractory non-oxide ceramics, with controlled compositions, under moderate conditions, and in processed forms. The goal of the work described in this dissertation was both to develop new processible precursors to technologically important ceramics and to achieve the formation of advanced materials in processed forms. One aspect of this research exploited previously developed preceramic precursors to boron carbide, boron nitride and silicon carbide for the generation of a wide variety of advanced materials: (1) ultra-high temperature ceramic (UHTC) structural materials composed of hafnium boride and related composite materials, (2) the quaternary borocarbide superconductors, and (3) on the nanoscale, non-oxide ceramic nanotubules. The generation of the UHTC and the quaternary borocarbide materials was achieved through a method that employs a processible polymer/metal(s) dispersion followed by subsequent pyrolyses. In the case of the UHTC, hafnium oxide, hafnium, or hafnium boride powders were dispersed in a suitable precursor to afford hafnium borides or related composite materials (HfB2/HfC, HfB2/HfN, HfB2/SiC) in high yields and purities. The quaternary borocarbide superconducting materials were produced from pyrolyses of dispersions containing appropriate stoichiometric amounts of transition metal, lanthanide metal, and the polyhexenyldecaborane polymer. Both chemical vapor deposition (CVD) based routes employing a molecular precursor and porous alumina templating routes paired with solution-based methodologies are shown to generate non-oxide ceramic nanotubules of boron carbide, boron nitride and silicon carbide compositions. In the final phase of this work, a new metal-catalyzed route to poly(1-alkenyl- o-carborane) homopolymers and related copolymers was developed. Both homopolymers of 1-alkenyl-o-carboranes (1-vinyl-, 1-butenyl-, 1-hexenyl-) and copolymers of 1-hexenyl-o-carborane and allyltrimethylsilane or 1-hexenyl-o-carborane and 6-hexenyldecaborane were synthesized via the Cp2ZrMe2/B(C6F5) 3 catalyst system. A copolymer containing 1-hexenyl-o-carborane and the cross-linking agent, 6-hexenyldecaborane, was synthetically designed which exhibits initial cross-linking at ˜250°C and then converts in 75% yields to boron carbide at 1250°C.

Lightweight bladder lined pressure vessels

DOEpatents

Mitlitsky, F.; Myers, B.; Magnotta, F.

1998-08-25

A lightweight, low permeability liner is described for graphite epoxy composite compressed gas storage vessels. The liner is composed of polymers that may or may not be coated with a thin layer of a low permeability material, such as silver, gold, or aluminum, deposited on a thin polymeric layer or substrate which is formed into a closed bladder using tori spherical or near tori spherical end caps, with or without bosses therein, about which a high strength to weight material, such as graphite epoxy composite shell, is formed to withstand the storage pressure forces. The polymeric substrate may be laminated on one or both sides with additional layers of polymeric film. The liner may be formed to a desired configuration using a dissolvable mandrel or by inflation techniques and the edges of the film sealed by heat sealing. The liner may be utilized in most any type of gas storage system, and is particularly applicable for hydrogen, gas mixtures, and oxygen used for vehicles, fuel cells or regenerative fuel cell applications, high altitude solar powered aircraft, hybrid energy storage/propulsion systems, and lunar/Mars space applications, and other applications requiring high cycle life. 19 figs.

Aeolian process of the dried-up riverbeds of the Hexi Corridor, China: a wind tunnel experiment.

PubMed

Zhang, Caixia; Wang, Xunming; Dong, Zhibao; Hua, Ting

2017-08-01

Wind tunnel studies, which remain limited, are an important tool to understand the aeolian processes of dried-up riverbeds. The particle size, chemical composition, and the mineral contents of sediments arising from the dried river beds are poorly understood. Dried-up riverbeds cover a wide area in the Hexi Corridor, China, and comprise a complex synthesis of different land surfaces, including aeolian deposits, pavement surfaces, and Takyr crust. The results of the present wind tunnel experiment suggest that aeolian transport from the dried-up riverbeds of the Hexi Corridor ranges from 0 to 177.04 g/m 2 /min and that dry riverbeds could be one of the main sources of dust emissions in this region. As soon as the wind velocity reaches 16 m/s and assuming that there are abundant source materials available, aeolian transport intensity increases rapidly. The dried-up riverbed sediment and the associated aeolian transported material were composed mainly of fine and medium sands. However, the transported samples were coarser than the bed samples, because of the sorting effect of the aeolian processes on the sediment. The aeolian processes also led to regional elemental migration and mineral composition variations.

Clinical Evaluation of an Unsintered Hydroxyapatite/Poly-L-Lactide Osteoconductive Composite Device for the Internal Fixation of Maxillofacial Fractures

PubMed Central

Sukegawa, Shintaro; Kanno, Takahiro; Katase, Naoki; Shibata, Akane; Takahashi, Yuka; Furuki, Yoshihiko

2016-01-01

Introduction: OSTEOTRANS MX (Takiron Co, Ltd, Osaka, Japan) is a resorbable osteosynthetic material composed of an unsintered hydroxyapatite/poly-l-lactide composite, and its osteoconductive capacity has been documented. The authors here report their clinical experience using OSTEOTRANS MX. Methods: The authors treated 35 patients (19 men, 16 women; age, 14–88 years; mean ± standard deviation, 38.4 ± 19.9 years) with maxillofacial fractures. The authors used standard surgery to stabilize fractures in all patients, fitting resorbable plates (thickness, 1.0 or 1.4 mm) and screws (diameter, 2 mm) according to Arbeitsgemeinschaft für Osteosynthesefragen/Association (AO) for the Study of Internal Fixation guidelines. Results: All patients eventually achieved satisfactory healing with favorable restoration of form and function without foreign body reaction. Complications occurred in 3 patients—plate exposure in 2 and discomfort in 1. However, fracture sites healed in all patients. Scanning electron microscopy revealed that the devices bonded directly to the bone without interposition of nonmineralized tissue. Conclusion: OSTEOTRANS MX is a useful material with few complications. Its osteoconductive bioactivity is advantageous for the early functional improvement of maxillofacial fractures. PMID:27428913

Laminated and Two-Dimensional Carbon-Supported Microwave Absorbers Derived from MXenes.

PubMed

Han, Meikang; Yin, Xiaowei; Li, Xinliang; Anasori, Babak; Zhang, Litong; Cheng, Laifei; Gogotsi, Yury

2017-06-14

Microwave absorbers with layered structures that can provide abundant interfaces are highly desirable for enhancing electromagnetic absorbing capability and decreasing the thickness. The atomically thin layers of two-dimensional (2D) transition-metal carbides (MXenes) make them a convenient precursor for synthesis of other 2D and layered structures. Here, laminated carbon/TiO 2 hybrid materials composed of well-aligned 2D carbon sheets with embedded TiO 2 nanoparticles were synthesized and showed excellent microwave absorption. Disordered 2D carbon layers with an unusual structure were obtained by annealing multilayer Ti 3 C 2 MXene in a CO 2 atmosphere. The minimum reflection coefficient of laminated carbon/TiO 2 composites reaches -36 dB, and the effective absorption bandwidth ranges from 3.6 to 18 GHz with the tunable thickness from 1.7 to 5 mm. The effective absorption bandwidth covers the whole Ku band (12.4-18 GHz) when the thickness of carbon/TiO 2 /paraffin composite is 1.7 mm. This study is expected to pave the way to the synthesis of carbon-supported absorbing materials using a large family of 2D carbides.

Use of Iba Techniques to Characterize High Velocity Thermal Spray Coatings

NASA Astrophysics Data System (ADS)

Trompetter, W.; Markwitz, A.; Hyland, M.

Spray coatings are being used in an increasingly wide range of industries to improve the abrasive, erosive and sliding wear of machine components. Over the past decade industries have moved to the application of supersonic high velocity thermal spray techniques. These coating techniques produce superior coating quality in comparison to other traditional techniques such as plasma spraying. To date the knowledge of the bonding processes and the structure of the particles within thermal spray coatings is very subjective. The aim of this research is to improve our understanding of these materials through the use of IBA techniques in conjunction with other materials analysis techniques. Samples were prepared by spraying a widely used commercial NiCr powder onto substrates using a HVAF (high velocity air fuel) thermal spraying technique. Detailed analysis of the composition and structure of the power particles revealed two distinct types of particles. The majority was NiCr particles with a significant minority of particles composing of SiO2/CrO3. When the particles were investigated both as raw powder and in the sprayed coating, it was surprising to find that the composition of the coating meterial remained unchanged during the coating process despite the high velocity application.

Physicochemical properties of aerosol released in the case of a fire involving materials used in the nuclear industry.

PubMed

Ouf, F-X; Mocho, V-M; Pontreau, S; Wang, Z; Ferry, D; Yon, J

2015-01-01

For industrial concerns, and more especially for nuclear applications, the characterization of soot is essential for predicting the behaviour of containment barriers in fire conditions. This study deals with the characterization (emission factor, composition, size, morphology, microstructure) of particles produced during thermal degradation of materials found in nuclear facilities (electrical cables, polymers, oil and solvents). Small-scale experiments have been conducted for oxygen concentrations [O2] ranging from 15% to 21% in order to imitate the oxygen depletion encountered during a confined fire. Particles denote distinct shapes, from aggregates composed of monomers with diameters ranging from 31.2 nm to 52.8 nm, to compact nanoparticles with diameters ranging from 15 nm to 400 nm, and their composition strongly depends on fuel type. Despite the organic to total carbon ratio (OC/TC), their properties are poorly influenced by the decrease in [O2]. Finally, two empirical correlations are proposed for predicting the OC/TC ratio and the monomer diameter, respectively, as a function of the fuel's carbon to hydrogen ratio and the emission factor. Copyright © 2014 Elsevier B.V. All rights reserved.

Glass-ceramic coated Mg-Ca alloys for biomedical implant applications.

PubMed

Rau, J V; Antoniac, I; Fosca, M; De Bonis, A; Blajan, A I; Cotrut, C; Graziani, V; Curcio, M; Cricenti, A; Niculescu, M; Ortenzi, M; Teghil, R

2016-07-01

Biodegradable metals and alloys are promising candidates for biomedical bone implant applications. However, due to the high rate of their biodegradation in human body environment, they should be coated with less reactive materials, such, for example, as bioactive glasses or glass-ceramics. Fort this scope, RKKP composition glass-ceramic coatings have been deposited on Mg-Ca(1.4wt%) alloy substrates by Pulsed Laser Deposition method, and their properties have been characterized by a number of techniques. The prepared coatings consist of hydroxyapatite and wollastonite phases, having composition close to that of the bulk target material used for depositions. The 100μm thick films are characterized by dense, compact and rough morphology. They are composed of a glassy matrix with various size (from micro- to nano-) granular inclusions. The average surface roughness is about 295±30nm due to the contribution of micrometric aggregates, while the roughness of the fine-texture particulates is approximately 47±4nm. The results of the electrochemical corrosion evaluation tests evidence that the RKKP coating improves the corrosion resistance of the Mg-Ca (1.4wt%) alloy in Simulated Body Fluid. Copyright © 2016 Elsevier B.V. All rights reserved.

Ries Bunte Breccia revisited: Indications for the presence of water in Itzing and Otting drill cores and implications for the emplacement process

NASA Astrophysics Data System (ADS)

Pietrek, Alexa; Kenkmann, Thomas

2016-07-01

We reassessed two drill cores of the Bunte Breccia deposits of the Ries crater, Germany. The objectives of our study were the documentation of evidence for water in the Bunte Breccia, the evaluation of how that water influenced the emplacement processes, and from which preimpact water reservoir it was derived. The Bunte Breccia in both cores can be structured into a basal layer composed mainly of local substrate material, overlain by texturally and compositionally diverse, crater-derived breccia units. The basal layer is composed of the youngest sediments (Tertiary clays and Upper Jurassic limestone) and has a razor-sharp boundary to the upper breccia units, which are composed of older rocks of Upper Jurassic to Upper Triassic age. Sparse material exchange occurred between the basal layer and the rest of the Bunte Breccia. Fluids predominantly came from the Tertiary and the Upper Triassic sandstone formation. In the basal layer, Tertiary clays were subjected to intense, ductile deformation, indicating saturation with water. This suggests that water was mixed into the matrix, creating a fluidized basal layer with a strong shear localization. In the upper units, Upper Triassic sandstones are intensely deformed by granular flow. The texture requires that the rocks were disaggregated into granular sand. Vaporization of pore water probably aided fragmentation of these rocks. In the Otting core, hot suevite (T > 600 °C) covered the Bunte Breccia shortly after its emplacement. Vertically oriented gas escape pipes in suevite partly emanate directly at the contact to the Bunte Breccia. They indicate that the Bunte Breccia contained a substantial amount of water in the upper part that was vaporized and escaped through these vents.

Analysis of the Impedance Resonance of Piezoelectric Multi-Fiber Composite Stacks

NASA Technical Reports Server (NTRS)

Sherrit, S.; Djrbashian, A.; Bradford, S C

2013-01-01

Multi-Fiber CompositesTM (MFC's) produced by Smart Materials Corp behave essentially like thin planar stacks where each piezoelectric layer is composed of a multitude of fibers. We investigate the suitability of using previously published inversion techniques for the impedance resonances of monolithic co-fired piezoelectric stacks to the MFCTM to determine the complex material constants from the impedance data. The impedance equations examined in this paper are those based on the derivation. The utility of resonance techniques to invert the impedance data to determine the small signal complex material constants are presented for a series of MFC's. The technique was applied to actuators with different geometries and the real coefficients were determined to be similar within changes of the boundary conditions due to change of geometry. The scatter in the imaginary coefficient was found to be larger. The technique was also applied to the same actuator type but manufactured in different batches with some design changes in the non active portion of the actuator and differences in the dielectric and the electromechanical coupling between the two batches were easily measureable. It is interesting to note that strain predicted by small signal impedance analysis is much lower than high field stains. Since the model is based on material properties rather than circuit constants, it could be used for the direct evaluation of specific aging or degradation mechanisms in the actuator as well as batch sorting and adjustment of manufacturing processes.

A chemiluminescence biosensor for the detection of thrombin based on the aptamer composites

NASA Astrophysics Data System (ADS)

Lin, Yanna; Li, Jianbo; Wang, Yanhui; Sun, Yuanling; Ding, Chaofan; Sun, Weiyan; Luo, Chuannan

2018-03-01

An efficient, rapid, simple and ultrasensitive chemiluminescence (CL) approach was proposed for thrombin detection based on the aptamer-thrombin recognition. The aptamer composites were synthesized in this work using graphene oxide (GO) as the backing material. The thrombin was adsorbed on the aptamer composites based on the aptamer-thrombin recognition. Thus, thrombin could be quantified by the difference value of the CL intensity between supernate of the sample and the mixture which composed of thrombin and coexisted substances. The CL intensity exhibits a stable response to thrombin over a concentration range from 2.5 × 10- 10 to 1 × 10- 9 mol·L- 1 with a detection limit as low as 8.3 × 10- 11 mol·L- 1, the relative standard deviation (RSD) was found to be 4.9% for 11 determinations of 1.25 × 10- 9 mol·L- 1 thrombin. Finally, the applicability of the method was verified by applying to serum samples. The recoveries were in the range of 90.3-101.0% with RSD of 2.6-3.2%.

Breccia 66055 and related clastic materials from the Descartes region, Apollo 16

NASA Technical Reports Server (NTRS)

Fruchter, J. S.; Kridelbaugh, S. J.; Robyn, M. A.; Goles, G. G.

1974-01-01

Trace and major element contents obtained by instrumental neutron activation are reported for a number of Apollo 16 soil samples and miscellaneous breccia fragments. In addition, data obtained by instrumental neutron activation and electron microprobe techniques along with petrographic descriptions are presented for selected subsamples of breccia 66055. The compositions of our soil samples can be modeled by mixtures of various amounts of anorthosite, anorthositic gabbro and low-K Fra Mauro basalt components. These mixtures are typical of those found in a number of petrographic surveys of the fines. Breccia 66055 is a complex regolith breccia which consists of at least four distinct types of microbreccias. No systematic relation with respect to stratigraphic age among the various microbreccia types was observed. Compositionally and texturally, the clasts which compose breccia 66055 are similar to a number of previously reported rock types from the Apollo 16 area. The entire breccia appears to have undergone a complex history of thermal metamorphism. We conclude from the study of these samples that the Cayley Formation is probably homogeneous in its gross compositional and petrographic aspects.

Crystal morphology variation in inkjet-printed organic materials

NASA Astrophysics Data System (ADS)

Ihnen, Andrew C.; Petrock, Anne M.; Chou, Tsengming; Samuels, Phillip J.; Fuchs, Brian E.; Lee, Woo Y.

2011-11-01

The recent commercialization of piezoelectric-based drop-on-demand inkjet printers provides an additive processing platform for producing and micropatterning organic crystal structures. We report an inkjet printing approach where macro- and nano-scale energetic composites composed of cyclotrimethylenetrinitramine (RDX) crystals dispersed in a cellulose acetate butyrate (CAB) matrix are produced by direct phase transformation from organic solvent-based all-liquid inks. The characterization of printed composites illustrates distinct morphological changes dependent on ink deposition parameters. When 10 pL ink droplets rapidly formed a liquid pool, a coffee ring structure containing dendritic RDX crystals was produced. By increasing the substrate temperature, and consequently the evaporation rate of the pooled ink, the coffee ring structure was mitigated and shorter dendrites from up to ∼1 to 0.2 mm with closer arm spacing from ∼15 to 1 μm were produced. When the nucleation and growth of RDX and CAB were confined within the evaporating droplets, a granular structure containing nanoscale RDX crystals was produced. The results suggest that evaporation rate and microfluidic droplet confinement can effectively be used to tailor the morphology of inkjet-printed energetic composites.

Polymer-directed crystallization of atorvastatin.

PubMed

Choi, Hyemin; Lee, Hyeseung; Lee, Min Kyung; Lee, Jonghwi

2012-08-01

Living organisms secrete minerals composed of peptides and proteins, resulting in "mesocrystals" of three-dimensional-assembled composite structures. Recently, this biomimetic polymer-directed crystallization technique has been widely applied to inorganic materials, although it has seldom been used with drugs. In this study, the technique was applied to the drowning-out crystallization of atorvastatin using various polymers. Nucleation and growth at optimized conditions successfully produced composite crystals with significant polymer contents and unusual characteristics. Atorvastatin composite crystals containing polyethylene glycol, polyacrylic acid, polyethylene imine, and chitosan showed a markedly decreased melting point and heat of fusion, improved stability, and sustained-release patterns. The use of hydroxypropyl cellulose yielded a unique combination of enhanced in vitro release and improved drug stability under a forced degradation condition. The formation hypothesis of unique mesocrystal structures was strongly supported by an X-ray diffraction pattern and substantial melting point reduction. This polymer-directed crystallization technique offers a novel and effective way, different from the solid dispersion approach, to engineer the release, stability, and processability of drug crystals. Copyright © 2012 Wiley Periodicals, Inc.

Hierarchical NiO-SiO2 composite hollow microspheres with enhanced adsorption affinity towards Congo red in water.

PubMed

Lei, Chunsheng; Zhu, Xiaofeng; Zhu, Bicheng; Yu, Jiaguo; Ho, Wingkei

2016-03-15

Hollow microspheres and hierarchical porous nanostructured materials with desired morphologies have gained remarkable attention for their potential applications in environmental technology. In this study, NiO-SiO2 hollow microspheres were prepared by co-precipitation with SiO2 and nickel salt as precursors, followed by dipping in alkaline solution and calcination. The samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption, and X-ray photoelectron spectroscopy. The synthesized hollow spheres were composed of a SiO2 shell and hierarchical porous NiO nanosheets on the surface. Adsorption experiments suggested that NiO-SiO2 composite particles were powerful adsorbents for removal of Congo red from water, with a maximum adsorption capacity of 204.1 mg/g. The high specific surface areas, hollow structures, and hierarchical porous surfaces of the hollow composite particles are suitable for various applications, including adsorption of pollutants, chemical separation, and water purification. Copyright © 2015 Elsevier Inc. All rights reserved.

Influence of Environment on Glandular Trichomes and Composition of Essential Oil of Perovskia abrotanoides Karel.

PubMed Central

Oreizi, Elaheh; Rahiminejad, Mohammad Reza; Asghari, Gholamreza

2014-01-01

Background: Perovskia abrotanoides Karel. is a medicinal plant used in Iranian folk medicine as a pain killer. Forty-one components have been identified in P. abrotanoides samples collected from Baluchistan Province, and 29 components have been recognized in samples collected from Khorasan Province. The leaves of P. abrotanoides have glandular trichomes (capitates and peltate) on both sides of the lamina. Objectives: This study aimed to evaluate the variation of oil constituents of the plant and illustrate the glandular trichomes types and then show the influence of environment on oil constituents and glandular trichomes. Materials and Methods: The essential oil of the plant was obtained using hydrodistillation and the analysis of oils carried out using GC-MS. The anatomical analysis of leaves was done by fixing, coloring, and photoing the sections. Results: Glandular trichomes composed of capitates and peltate trichomes. The essential oil composition differs. Viridiflora and neryl acetate were not identified in yellow glandular trichomes. Conclusions: It seems that there is no relation between anatomical characteristics of the plant leaves and its essential oil composition. PMID:25625046

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

Park, Joong Sun; Mane, Anil U.; Elam, Jeffrey W.

Atomic layer deposition (ALD) of the well-known Al 2O 3 on a LiCoO 2 system is compared with that of a newly developed AlW xF y material. ALD coatings (~1 nm thick) of both materials are shown to be effective in improving cycle life through mitigation of surface-induced capacity losses. However, the behaviors of Al 2O 3 and AlW xF y are shown to be significantly different when coated directly on cathode particles versus deposition on a composite electrode composed of active materials, carbons, and binders. Electrochemical impedance spectroscopy, galvanostatic intermittent titration techniques, and four-point measurements suggest that electron transportmore » is more limited in LiCoO 2 particles coated with Al 2O 3 compared with that in particles coated with AlW xF y. Here, the results show that proper design/choice of coating materials (e.g., AlW xF y) can improve capacity retention without sacrificing electron transport and suggest new avenues for engineering electrode–electrolyte interfaces to enable high-voltage operation of lithium-ion batteries.« less

Updated optical read/write memory system components

NASA Technical Reports Server (NTRS)

1973-01-01

The fabrication of an updated block data composer and holographic storage array for a breadboard holographic read/write memory system is described. System considerations such as transform optics and controlled aberration lens design are described along with the block data composer, photoplastic recording materials, and material development.

ENGLISH WRITING, APPROACHES TO COMPOSITION.

ERIC Educational Resources Information Center

Euclid English Demonstration Center, OH.

THIS COLLECTION OF PAPERS BY STAFF MEMBERS OF THE EUCLID ENGLISH DEMONSTRATION CENTER FOCUSES ON APPROACHES TO THE TEACHING OF COMPOSITION IN THE JUNIOR HIGH SCHOOL. THE PAPERS ARE (1) "LITERATURE AND COMPOSITION," BY JAMES F. MCCAMPBELL, (2) "COMPOSING--EPIPHANY AND DETAIL," BY JOSEPH DYESS, (3) "THE LANGUAGE COMPOSITION…

Composite flexible blanket insulation

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A. (Inventor); Lowe, David M. (Inventor)

1994-01-01

An improved composite flexible blanket insulation is presented comprising top silicon carbide having an interlock design, wherein the reflective shield is composed of single or double aluminized polyimide and wherein the polyimide film has a honeycomb pattern.

Damage, Self-Healing, and Hysteresis in Spider Silks

PubMed Central

De Tommasi, D.; Puglisi, G.; Saccomandi, G.

2010-01-01

Abstract In this article, we propose a microstructure-based continuum model to describe the material behavior of spider silks. We suppose that the material is composed of a soft fraction with entropic elasticity and a hard, damageable fraction. The hard fraction models the presence of stiffer, crystal-rich, oriented regions and accounts for the effect of softening induced by the breaking of hydrogen bonds. To describe the observed presence of crystals with different size, composition, and orientation, this hard fraction is modeled as a distribution of materials with variable properties. The soft fraction describes the remaining regions of amorphous material and is here modeled as a wormlike chain. During stretching, we consider the effect of bond-breaking as a transition from the hard- to the soft-material phase. As we demonstrate, a crucial effect of bond-breaking that accompanies the softening of the material is an increase in contour length associated with chains unraveling. The model describes also the self-healing properties of the material by assuming partial bond reconnection upon unloading. Despite its simplicity, the proposed mechanical system reproduces the main experimental effects observed in cyclic loading of spider silks. Moreover, our approach is amenable to two- or three-dimensional extensions and may prove to be a useful tool in the field of microstructure optimization for bioinspired materials. PMID:20441758

Application of scanning laser Doppler vibrometry for delamination detection in composite structures

NASA Astrophysics Data System (ADS)

Kudela, Pawel; Wandowski, Tomasz; Malinowski, Pawel; Ostachowicz, Wieslaw

2017-12-01

In this paper application of scanning laser Doppler vibrometry for delamination detection in composite structures was presented. Delamination detection was based on a guided wave propagation method. In this papers results from numerical and experimental research were presented. In the case of numerical research, the Spectral Element Method (SEM) was utilized, in which a mesh was composed of 3D spectral elements. SEM model included also a piezoelectric transducer. In the experimental research guided waves were excited using the piezoelectric transducer whereas the sensing process was conducted using scanning laser Doppler vibrometer (SLDV). Analysis of guided wave propagation and its interaction with delamination was based on a full wavefield approach. Attention was focused on interactions of guided waves with delamination manifested by A0 mode reflection, A0 mode entrapment, and S0/A0 mode conversion. Delamination was simulated by a teflon insert located between plies of composite material. Results of interaction with symmetrically and nonsymmetrical placed delamination (in respect to the composite sample thickness) were presented. Moreover, the authors investigated different size of delaminations. Damage detection was based on a new signal processing algorithm proposed by the authors. In this approach the weighted RMS was utilized selectively. It means that the summation in RMS formula was performed only for a specially selected time instances. Results for simple composite panels, panel with honeycomb core, and real stiffened composite panel from the aircraft were presented.

A molecular investigation of soil organic carbon composition across a subalpine catchment

USGS Publications Warehouse

Hsu, Hsiao-Tieh; Lawrence, Corey R.; Winnick, Matthew J.; Bargar, John R.; Maher, Katharine

2018-01-01

The dynamics of soil organic carbon (SOC) storage and turnover are a critical component of the global carbon cycle. Mechanistic models seeking to represent these complex dynamics require detailed SOC compositions, which are currently difficult to characterize quantitatively. Here, we address this challenge by using a novel approach that combines Fourier transform infrared spectroscopy (FT-IR) and bulk carbon X-ray absorption spectroscopy (XAS) to determine the abundance of SOC functional groups, using elemental analysis (EA) to constrain the total amount of SOC. We used this SOC functional group abundance (SOC-fga) method to compare variability in SOC compositions as a function of depth across a subalpine watershed (East River, Colorado, USA) and found a large degree of variability in SOC functional group abundances between sites at different elevations. Soils at a lower elevation are predominantly composed of polysaccharides, while soils at a higher elevation have more substantial portions of carbonyl, phenolic, or aromatic carbon. We discuss the potential drivers of differences in SOC composition between these sites, including vegetation inputs, internal processing and losses, and elevation-driven environmental factors. Although numerical models would facilitate the understanding and evaluation of the observed SOC distributions, quantitative and meaningful measurements of SOC molecular compositions are required to guide such models. Comparison among commonly used characterization techniques on shared reference materials is a critical next step for advancing our understanding of the complex processes controlling SOC compositions.

Developing a novel magnesium glycerophosphate/silicate-based organic-inorganic composite cement for bone repair.

PubMed

Ding, Zhengwen; Li, Hong; Wei, Jie; Li, Ruijiang; Yan, Yonggang

2018-06-01

Considering that the phospholipids and glycerophosphoric acid are the basic materials throughout the metabolism of the whole life period and the bone is composed of organic polymer collagen and inorganic mineral apatite, a novel self-setting composite of magnesium glycerophosphate (MG) and di-calcium silicate(C2S)/tri-calcium silicate(C3S) was developed as bio-cement for bone repair, reconstruction and regeneration. The composite was prepared by mixing the MG, C2S and C3S with the certain ratios, and using the deionized water and phosphoric acid solution as mixed liquid. The combination and formation of the composites was characterized by FTIR, XPS and XRD. The physicochemical properties were studied by setting time, compressive strength, pH value, weight loss in the PBS and surface change by SEM-EDX. The biocompatibility was evaluated by cell culture in the leaching solution of the composites. The preliminary results showed that when di- and tri-calcium silicate contact with water, there are lots of Ca(OH) 2 generated making the pH value of solution is higher than 9 which is helpful for the formation of hydroxyapatite(HA) that is the main bone material. The new organic-inorganic self-setting bio-cements showed initial setting time is ranged from 20 min to 85 min and the compressive strength reached 30 MPa on the 7th days, suitable as the bone fillers. The weight loss was 20% in the first week, and 25% in the 4th week. Meanwhile, the new HA precipitated on the composite surface during the incubation in the SBF showed bioactivity. The cell cultured in the leaching liquid of the composite showed high proliferation inferring the new bio-cement has good biocompatibility to the cells. Copyright © 2018 Elsevier B.V. All rights reserved.

Volcanoes Behave as Composite Materials: Implications for Modeling Magma Chambers, Dikes, and Surface Deformation

NASA Astrophysics Data System (ADS)

Leiss, B.; Gudmundsson, A.; Philipp, S. L.

2005-12-01

By definition, composite volcanoes are composed of numerous alternating material units or layers such as lavas, sediments, and pyroclastics. Commonly, these layers have widely different mechanical properties. In particular, some lava flows and welded pyroclastic flows may be stiff (with a high Young's modulus), whereas others, such as non-welded pyroclastic units and sediments, may be soft (with a low Young's modulus). As a consequence, even if the loading (tectonic stress, magmatic pressure, or displacement) is uniform, the stresses within the composite volcano will vary widely. In this sense, the behavior of composite volcanoes is similar to that of general composite materials. The deformation of the surface of a volcano during an unrest period results from stresses generated by processes and parameters such as fluid pressure in a geothermal field or a magma chamber, a regional tectonic event, and a dike injection. Here we present new numerical models on mechanics of magma chambers and dikes, and the associated surface deformation of composite volcanoes. The models show that the surface deformation during magma-chamber inflation and deflation depends much on the chamber geometry, the loading conditions, and the mechanical properties of the rock units that constitute the volcano. The models also indicate that the surface deformation induced by a propagating dike depends much on the mechanical properties of the layers between the dike tip and the surface. In particular, the numerical results show that soft layers and weak contacts between layers may suppress the dike-induced tensile stresses and the associated surface deformation. Many dikes may therefore become injected and arrested at shallow depths in a volcano while giving rise to little or no surface deformation. Traditional analytical surface-deformation models such as a point source (Mogi model) for a magma-chamber pressure change and a dislocation for a dike normally assume the volcano to behave as a homogeneous, isotropic half space. The present numerical results, combined with field studies, indicate that such analytical models may yield results that have little similarity with the actual structure being modeled.

Tunable Gas Sensing Gels by Cooperative Assembly

PubMed Central

Hussain, Abid; Semeano, Ana T. S.; Palma, Susana I. C. J.; Pina, Ana S.; Almeida, José; Medrado, Bárbara F.; Pádua, Ana C. C. S.; Carvalho, Ana L.; Dionísio, Madalena; Li, Rosamaria W. C.; Gamboa, Hugo; Ulijn, Rein V.; Gruber, Jonas; Roque, Ana C. A.

2017-01-01

The cooperative assembly of biopolymers and small molecules can yield functional materials with precisely tunable properties. Here, the fabrication, characterization, and use of multicomponent hybrid gels as selective gas sensors are reported. The gels are composed of liquid crystal droplets self-assembled in the presence of ionic liquids, which further coassemble with biopolymers to form stable matrices. Each individual component can be varied and acts cooperatively to tune gels’ structure and function. The unique molecular environment in hybrid gels is explored for supramolecular recognition of volatile compounds. Gels with distinct compositions are used as optical and electrical gas sensors, yielding a combinatorial response conceptually mimicking olfactory biological systems, and tested to distinguish volatile organic compounds and to quantify ethanol in automotive fuel. The gel response is rapid, reversible, and reproducible. These robust, versatile, modular, pliant electro-optical soft materials possess new possibilities in sensing triggered by chemical and physical stimuli. PMID:28747856

Imparting large macroscopic changes with small changes in polypeptide composition

NASA Astrophysics Data System (ADS)

Sing, Michelle; McKinley, Gareth; Olsen, Bradley

Block copolymers composed of polypeptides provide an excellent platform for exploring the underlying physics surrounding macroscopic associative network behavior. Previous work in our group has elucidated a difference in the mechanical properties of two nearly identical elastin-like polypeptide (ELP) endblocks. In poly(ELP)s, this substitution is known to result in tighter beta turns. These beta turns exhibit slower responses to changes in temperature within the material. Under shear, the modulus for the alanine-containing ELP triblock is almost three times higher than the glycine-containing ELP. Additionally, preliminary tensile tests show higher stress and strain at break for the alanine ELP triblock. We are able to explain the reasons for this behavior using a variety of spectroscopic and analytical techniques. Small angle neutron and x-ray scattering indicate differences in ordering between the alanine and glycine containing ELP materials both in shear and in stagnant flow.

Flash pyrolysis of forestry residues from the Portuguese Central Inland Region within the framework of the BioREFINA-Ter project.

PubMed

Amutio, Maider; Lopez, Gartzen; Alvarez, Jon; Moreira, Rui; Duarte, Gustavo; Nunes, Joao; Olazar, Martin; Bilbao, Javier

2013-02-01

The feasibility of the valorization by flash pyrolysis of forest shrub wastes, namely bushes (Cytisus multiflorus, Spartium junceum, Acacia dealbata and Pterospartum tridentatum) has been studied in a conical spouted bed reactor operating at 500 °C, with a continuous biomass feed and char removal. High bio-oil yields in the 75-80 wt.% range have been obtained for all of the materials, with char yields between 16 and 23 wt.% and low gas yields (4-5 wt.%). Bio-oils are composed mainly of water (accounting for a concentration in the 34-40 wt.% range in the bio-oil), phenols, ketones, acids and furans, with lower contents of saccharides, aldehydes and alcohols. Although their composition depends on the raw material, the compounds are similar to those obtained with more conventional feedstocks. Copyright © 2012 Elsevier Ltd. All rights reserved.

Chiral optical response of planar and symmetric nanotrimers enabled by heteromaterial selection.

PubMed

Banzer, Peter; Woźniak, Paweł; Mick, Uwe; De Leon, Israel; Boyd, Robert W

2016-10-13

Chirality is an intriguing property of certain molecules, materials or artificial nanostructures, which allows them to interact with the spin angular momentum of the impinging light field. Due to their chiral geometry, they can distinguish between left- and right-hand circular polarization states or convert them into each other. Here we introduce an approach towards optical chirality, which is observed in individual two-dimensional and geometrically mirror-symmetric nanostructures. In this scheme, the chiral optical response is induced by the chosen heterogeneous material composition of a particle assembly and the corresponding resonance behaviour of the constituents it is built from, which breaks the symmetry of the system. As a proof of principle, we investigate such a structure composed of individual silicon and gold nanoparticles both experimentally, as well as numerically. Our proposed concept constitutes an approach for designing two-dimensional chiral media tailored at the nanoscale, allowing for high tunability of their optical response.

Anodic Behaviour of High Nitrogen-Bearing Steel in PEMFC Environments

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

Wang, H.; Turner, J. A.

2008-02-01

High nitrogen-bearing stainless steels, AISI Type 201 and AL219, were investigated in simulated polymer electrolyte membrane fuel cell (PEMFC) environments to assess the use of these materials in fuel cell bipolar plate applications. Both steels exhibit better corrosion behavior than 316L steel in the same environments. Type 201 steel shows similar but lower interfacial contact resistance (ICR) than 316L, while AL219 steel shows higher ICR than 316L. X-ray photoelectron spectroscopy (XPS) analysis shows that the air-formed films on Type 201 and AL219 are composed of iron oxides, chromium oxide, and manganese oxide. Iron oxides dominate the composition of the air-formedmore » film, specially the outer layer. Chromium oxide dominates passive films. Surface film thicknesses were estimated. The results suggest that high nitrogen-bearing stainless steels are promising materials for PEMFC bipolar plates.« less

Emission Testing Results of Thermally Stable, Metamaterial, Selective-Emitters for Thermophotovoltaics

NASA Astrophysics Data System (ADS)

Levinson, Katherine; Naka, Norihito; Pfiester, Nicole; Licht, Abigail; Vandervelde, Tom

2015-03-01

In thermophotovoltaics, the energy from a heated emitter is converted to electricity by a photovoltaic diode. A selective emitter can be used to emit a narrow band of wavelengths tailored to the bandgap of the photovoltaic diode. This spectral shaping improves the conversion efficiency of the diode and reduces undesirable diode heating. In our research, we study selective emitters based on metamaterials composed of repeating nanoscale structures. The emission characteristics of these materials vary based on the compositional structure, allowing the emitted spectrum to be tunable. Simulations were performed with CST Microwave Studio to design emitters with peak wavelengths ranging from 1-10 microns. The structures were then fabricated using physical vapor deposition and electron beam lithography on a sapphire substrate. Emitter materials studied include gold, platinum, and iridium. Here we report on the emission spectra of the selective emitters and the post-heating structural integrity.

Synthetic magnetoelectric coupling in a nanocomposite multiferroic

DOE PAGES

Jain, P.; Wang, Q.; Roldan, M.; ...

2015-03-13

Given the paucity of single phase multiferroic materials (with large ferromagnetic moment), composite systems seem an attractive solution to realize magnetoelectric coupling between ferromagnetic and ferroelectric order parameters. Despite having antiferromagnetic order, BiFeO₃ (BFO) has nevertheless been a key material due to excellent ferroelectric properties at room temperature. We studied a superlattice composed of 8 repetitions of 6 unit cells of La₀.₇Sr₀.₃MnO₃ (LSMO) grown on 5 unit cells of BFO. Significant net uncompensated magnetization in BFO, an insulating superlattice, is demonstrated using polarized neutron reflectometry. Remarkably, the magnetization enables magnetic field to change the dielectric properties of the superlattice, whichmore » we cite as an example of synthetic magnetoelectric coupling. Importantly, controlled creation of magnetic moment in BFO is a much needed path toward design and implementation of integrated oxide devices for next generation magnetoelectric data storage platforms.« less

Supramolecular Amino Acid Based Hydrogels: Probing the Contribution of Additive Molecules using NMR Spectroscopy

PubMed Central

Ramalhete, Susana M.; Nartowski, Karol P.; Sarathchandra, Nichola; Foster, Jamie S.; Round, Andrew N.; Angulo, Jesús

2017-01-01

Abstract Supramolecular hydrogels are composed of self‐assembled solid networks that restrict the flow of water. l‐Phenylalanine is the smallest molecule reported to date to form gel networks in water, and it is of particular interest due to its crystalline gel state. Single and multi‐component hydrogels of l‐phenylalanine are used herein as model materials to develop an NMR‐based analytical approach to gain insight into the mechanisms of supramolecular gelation. Structure and composition of the gel fibres were probed using PXRD, solid‐state NMR experiments and microscopic techniques. Solution‐state NMR studies probed the properties of free gelator molecules in an equilibrium with bound molecules. The dynamics of exchange at the gel/solution interfaces was investigated further using high‐resolution magic angle spinning (HR‐MAS) and saturation transfer difference (STD) NMR experiments. This approach allowed the identification of which additive molecules contributed in modifying the material properties. PMID:28401991

Biomineralization of a Self-assembled, Soft-Matrix Precursor: Enamel

NASA Astrophysics Data System (ADS)

Snead, Malcolm L.

2015-04-01

Enamel is the bioceramic covering of teeth, a composite tissue composed of hierarchical organized hydroxyapatite crystallites fabricated by cells under physiologic pH and temperature. Enamel material properties resist wear and fracture to serve a lifetime of chewing. Understanding the cellular and molecular mechanisms for enamel formation may allow a biology-inspired approach to material fabrication based on self-assembling proteins that control form and function. A genetic understanding of human diseases exposes insight from nature's errors by exposing critical fabrication events that can be validated experimentally and duplicated in mice using genetic engineering to phenocopy the human disease so that it can be explored in detail. This approach led to an assessment of amelogenin protein self-assembly that, when altered, disrupts fabrication of the soft enamel protein matrix. A misassembled protein matrix precursor results in loss of cell-to-matrix contacts essential to fabrication and mineralization.

Physical properties and biocompatibility of chitosan/soy blended membranes.

PubMed

Silva, S S; Santos, M I; Coutinho, O P; Mano, J F; Reis, R L

2005-06-01

Blends of polysaccharides and proteins are a source for the development of novel materials with interesting and tailorable properties, with potential to be used in a range of biomedical applications. in this work a series of blended membranes composed by chitosan and soy protein isolate was prepared by solvent casting methodology. in addition, cross-linking was performed in situ with glutaraldehyde solutions in the range 5x10(-3)-0.1 M. Furthermore, the influence of the composition and cross-linking on the degradation behaviour, water uptake and cell adhesion was investigated. The obtained results showed that the incorporation of chitosan, associated to network formation by cross linking, promoted a slight decrease of water absorption and a slower degradability of the membranes. Moreover, direct contact biocompatibility studies, with L929 cells, indicate that the cross-linking enhances the capability of the material to support cell growth.

Three-dimensional sulphur/nitrogen co-doped reduced graphene oxide as high-performance supercapacitor binder-free electrodes

NASA Astrophysics Data System (ADS)

Huo, Jinghao; Zheng, Peng; Wang, Xiaofei; Guo, Shouwu

2018-06-01

Sulphur/nitrogen co-doped reduced graphene oxide (SNG) aerogels were prepared by a simple solvothermal method with l-cysteine-assisted in ethylene glycol. The morphology and composition tests showed that the S/N heteroatoms were evenly distributed on SNG microsheets, and these microsheets were further composed of SNG aerogels with three-dimensional (3D) porous structure. The cyclic voltammetry and galvanostatic charge/discharge tests illustrated the SNG bind-free electrode possessed electric double-layer capacitance and pseudocapacitance, and had a capacitance of 254 F g-1 at a current density of 1 A g-1. After the 5000 cycles tests, the capacitance retained 83.54% at a current density of 2 A g-1. Meanwhile, the electrochemical impedance spectroscopy data shown the electrode materials had excellent capacity and good conductivity. Hence, the SNG aerogel prepared by l-cysteine-assisted solvothermal method is a great material for high-performance supercapacitors.

Epitaxial growth of hybrid nanostructures

NASA Astrophysics Data System (ADS)

Tan, Chaoliang; Chen, Junze; Wu, Xue-Jun; Zhang, Hua

2018-02-01

Hybrid nanostructures are a class of materials that are typically composed of two or more different components, in which each component has at least one dimension on the nanoscale. The rational design and controlled synthesis of hybrid nanostructures are of great importance in enabling the fine tuning of their properties and functions. Epitaxial growth is a promising approach to the controlled synthesis of hybrid nanostructures with desired structures, crystal phases, exposed facets and/or interfaces. This Review provides a critical summary of the state of the art in the field of epitaxial growth of hybrid nanostructures. We discuss the historical development, architectures and compositions, epitaxy methods, characterization techniques and advantages of epitaxial hybrid nanostructures. Finally, we provide insight into future research directions in this area, which include the epitaxial growth of hybrid nanostructures from a wider range of materials, the study of the underlying mechanism and determining the role of epitaxial growth in influencing the properties and application performance of hybrid nanostructures.

A Circum-terrestrial Compositional Filter

NASA Technical Reports Server (NTRS)

Chapman, C. R.; Greenberg, R.

1985-01-01

A major question about the moon is its under abundance of iron. It is the purpose of this research to understand whether a metal-silicate fractionation of heliocentrically orbiting bodies can be achieved through collisional interactions with a circum-terrestrial swarm. Rates of diffusion are investigated and the mutual collisional destruction within the population is examined. The interactions of these differentiated planetesimals and their collisional products (both silicate mantle fragments and iron cores) with a swarm of Earth orbiting lunesimals (perhaps ejecta from the Earth) of km scale, totaling a mass of order 0.1 lunar mass, extending out 10 or 20 Earth radii are considered. It is found that such a small near Earth population of lunesimals can filter out silicate rich material, while passing iron cores, and form a moon composed partly of terrestrial material, but more substantially of the captured silicate rich portions of the planetesimals.

Moving Composition: Writing in a Mobile World

ERIC Educational Resources Information Center

Herron, Josh Paul

2017-01-01

We live in an increasingly mobile society on many levels. Mobile devices, including the smartphone, tablet, and wearables, allow for composing and communicating from anywhere and in new ways, a phenomenon that is especially deserving of attention by composition studies scholars and teachers. Mobile composition processes are impacted by the…

High temperature polymer concrete

DOEpatents

Fontana, J.J.; Reams, W.

1984-05-29

This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system.

Asymmetric Semiconductor Nanorod/Oxide Nanoparticle Hybrid Materials: Model Nanomaterials for Light-Activated Formation of Fuels from Sunlight. Formal Progress Report -- Award DE-FG02-05ER15753

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

Armstrong, Neal R.

Executive Summary on Project Accomplishments: We focused our efforts for this project on the synthesis and characterization of semiconductor nanomaterials composed of semiconductor nanorods (NRs - e.g., CdSe, CdSe@CdS, CdS) with metal (Au, Pt, Co) or metal oxide (CoxOy) nanoparticle (NP) “tips.” These systems are attractive model systems where control of spatial, energetic and compositional features of both NRs and NP tips potentially enhances the efficiency of photogeneration and directional transport of charges, and photoelectrochemical conversion of sunlight to fuels. Synthetic methods to control material dimensions (20-200 nm in length), topology (one vs. two NP tips) and NR/NP tip compositionsmore » have been developed in the current project period (Pyun). We also achieved, for the first time in heterostructured nanorod materials, estimates of both valence band energies (E VB) and conduction band energies (E CB), using unique combinations of in vacuuo ultraviolet photoelectron spectroscopy (UPS, Armstrong), and waveguide spectroelectrochemistry (Saavedra), respectively. The spectroelectrochemical measurements in particular provide a unique path to estimation of E CB, and the distribution in E CB brought about by modification of NR composition. The combination of both approaches promises to be universally applicable to the characterization of energetics in nanomaterials of interest both for photovoltaic and sunlight-to-fuel photoelectrochemical assemblies.« less

Replacement of long segments of the esophagus with a collagen-silicone composite tube.

PubMed

Takimoto, Y; Nakamura, T; Teramachi, M; Kiyotani, T; Shimizu, Y

1995-01-01

Artificial esophagi designed thus far can be classified into three types in terms of the materials used: natural, artificial, and composite. In conventional models, even when artificial esophagi were made of ideal materials with high tissue affinity, they remained in the tissue as a foreign body, and therefore were not free of the complications caused by implanted material. The authors have designed a new type of artificial esophagus composed of a Silicone tube covered with nonantigenic collagen. The novel feature of this artificial esophagus is that the prosthesis does not remain in the implanted site, but is replaced by regenerated host tissue. Using this artificial esophagus, the authors have already succeeded in replacing a 5 cm gap in the esophagus. In this study, replacement of longer portions of the esophagus was assessed in seven dogs using a 10 cm long artificial esophagus. Stenosis did not occur in five of the seven dogs and, consequently, these dogs survived by oral feeding alone for more than 6 months without dry weight loss. The other two animals died of anesthetic accidents at the time of stent removal 6 weeks after surgery. In both cases, the internal surface of the neoesophagus was covered with a polylayer of squamous epithelium. Regenerated esophagi had normal esophageal glands and immature muscle tissue. It is therefore concluded that this new artificial esophagus is also applicable for replacement of long segments of esophagus.

Anthracite-Derived Dual-Phase Carbon-Coated Li3V2(PO4)3 as High-Performance Cathode Material for Lithium Ion Batteries.

PubMed

Ding, Xiao-Kai; Zhang, Lu-Lu; Yang, Xue-Lin; Fang, Hui; Zhou, Ying-Xian; Wang, Ji-Qing; Ma, Di

2017-12-13

In this study, low cost anthracite-derived dual-phase carbon-coated Li 3 V 2 (PO 4 ) 3 composites have been successfully prepared via a traditional solid-phase method. XRD results show that the as-prepared samples have high crystallinity and anthracite introduction has no influence on the LVP crystal structure. The LVP/C particles are uniformly covered with a dual-phase carbon layer composed of amorphous carbon and graphitic carbon. The effect of the amount of anthracite on the battery performance of LVP as a cathode material has also been studied. The LVP/C composite obtained with 10 wt % anthracite (LVP/C-10) delivers the highest initial charge/discharge capacities of 186.1/168.2 mAh g -1 at 1 C and still retains the highest discharge capacity of 134.0 mAh g -1 even after 100 cycles. LVP/C-10 also displays an outstanding average capacity of 140.8 mAh g -1 at 5 C. The superior rate capability and cycling stability of LVP/C-10 is ascribed to the reduced particle size, decreased charge-transfer resistance, and improved lithium ion diffusion coefficient. Our results demonstrate that using anthracite as a carbon source opens up a new strategy for larger-scale synthesis of LVP and other electrode materials with poor electronic conductivity for lithium ion batteries.

Effect of PVC and iron materials on Mn(II) deposition in drinking water distribution systems.

PubMed

Cerrato, José M; Reyes, Lourdes P; Alvarado, Carmen N; Dietrich, Andrea M

2006-08-01

Polyvinyl chloride (PVC) and iron pipe materials differentially impacted manganese deposition within a drinking water distribution system that experiences black water problems because it receives soluble manganese from a surface water reservoir that undergoes biogeochemical cycling of manganese. The water quality study was conducted in a section of the distribution system of Tegucigalpa, Honduras and evaluated the influence of iron and PVC pipe materials on the concentrations of soluble and particulate iron and manganese, and determined the composition of scales formed on PVC and iron pipes. As expected, total Fe concentrations were highest in water from iron pipes. Water samples obtained from PVC pipes showed higher total Mn concentrations and more black color than that obtained from iron pipes. Scanning electron microscopy demonstrated that manganese was incorporated into the iron tubercles and thus not readily dislodged from the pipes by water flow. The PVC pipes contained a thin surface scale consisting of white and brown layers of different chemical composition; the brown layer was in contact with the water and contained 6% manganese by weight. Mn composed a greater percentage by weight of the PVC scale than the iron pipe scale; the PVC scale was easily dislodged by flowing water. This research demonstrates that interactions between water and the infrastructure used for its supply affect the quality of the final drinking water.

Fabrication and characterization of poly-(ε)-caprolactone and bioactive glass composites for tissue engineering applications.

PubMed

Mohammadkhah, Ali; Marquardt, Laura M; Sakiyama-Elbert, Shelly E; Day, Delbert E; Harkins, Amy B

2015-04-01

Much work has focused on developing synthetic materials that have tailored degradation profiles and physical properties that may prove useful in developing biomaterials for tissue engineering applications. In the present study, three different composite sheets consisting of biodegradable poly-ε-caprolactone (PCL) and varying types of bioactive glass were investigated. The three composites were composed of 50wt.% PCL and (1) 50wt.% 13-93 B3 borate glass particles, (2) 50wt.% 45S5 silicate glass particles, or (3) a blend of 25wt.% 13-93 B3 and 25wt.% 45S5 glass particles. Degradation profiles determined for each composite showed the composite that contained only 13-93 B3 borate glass had a higher degradation rate compared to the composite containing only 45S5 silicate glass. Uniaxial tensile tests were performed on the composites to determine the effect of adding glass to the polymer on mechanical properties. The peak stress of all of the composites was lower than that of PCL alone, but 100% PCL had a higher stiffness when pre-reacted in cell media for 6weeks, whereas composite sheets did not. Finally, to determine whether the composite sheets would maintain neuronal growth, dorsal root ganglia isolated from embryonic chicks were cultured on composite sheets, and neurite outgrowth was measured. The bioactive glass particles added to the composites showed no negative effects on neurite extension, and neurite extension increased on PCL:45S5 PCL:13-93 B3 when pre-reacted in media for 24h. This work shows that composite sheets of PCL and bioactive glass particles provide a flexible biomaterial for neural tissue engineering applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Major- and minor-metal composition of three distinct solid material fractions associated with Juan de Fuca hydrothermal fluids (northeast Pacific), and calculation of dilution fluid samples

USGS Publications Warehouse

Hinkley, T.K.; Seeley, J.L.; Tatsumoto, M.

1988-01-01

Three distinct types of solid material are associated with each sample of the hydrothermal fluid that was collected from the vents of the Southern Juan de Fuca Ridge. The solid materials appear to be representative of deposits on ocean floors near mid-ocean ridges, and interpretation of the chemistry of the hydrothermal solutions requires understanding of them. Sr isotopic evidence indicates that at least two and probably all three of these solid materials were removed from the solution with which they are associated, by precipitation or adsorption. This occurred after the "pure" hydrothermal fluid was diluted and thoroughly mixed with ambient seawater. The three types of solid materials, are, respectively, a coarse Zn- and Fe-rich material with small amounts of Na and Ca; a finer material also rich in Zn and Fe, but with alkali and alkaline-earth metals; and a scum composed of Ba or Zn, with either considerable Fe or Si, and Sr. Mineral identification is uncertain because of uncertain anion composition. Only in the cases of Ba and Zn were metal masses greater in solid materials than in the associated fluids. For all other metals measured, masses in fluids dwarf those in solids. The fluids themselves contain greater concentrations of all metals measured, except Mg, than seawater. We discuss in detail the relative merits of two methods of determining the mixing proportions of "pure" hydrothermal solution and seawater in the fluids, one based on Sr isotopes, and another previously used method based on Mg concentrations. Comparison of solute concentrations in the several samples shows that degree of dilution of "pure" hydrothermal solutions by seawater, and amounts of original solutes that were removed from it as solid materials, are not related. There is no clear evidence that appreciable amounts of solid materials were not conserved (lost) either during or prior to sample collection. ?? 1988.

Abundant Solar Nebula Solids in Comets

NASA Technical Reports Server (NTRS)

Messenger, S.; Keller, L. P.; Nakamura-Messenger, K.; Nguyen, A. N.; Clemett, S.

2016-01-01

Comets have been proposed to consist of unprocessed interstellar materials together with a variable amount of thermally annealed interstellar grains. Recent studies of cometary solids in the laboratory have shown that comets instead consist of a wide range of materials from across the protoplanetary disk, in addition to a minor complement of interstellar materials. These advances were made possible by the return of direct samples of comet 81P/Wild 2 coma dust by the NASA Stardust mission and recent advances in microscale analytical techniques. Isotopic studies of 'cometary' chondritic porous interplanetary dust particles (CP-IDPs) and comet 81P/Wild 2 Stardust samples show that preserved interstellar materials are more abundant in comets than in any class of meteorite. Identified interstellar materials include sub-micron-sized presolar silicates, oxides, and SiC dust grains and some fraction of the organic material that binds the samples together. Presolar grain abundances reach 1 weight percentage in the most stardust-rich CP-IDPs, 50 times greater than in meteorites. Yet, order of magnitude variations in presolar grain abundances among CP-IDPs suggest cometary solids experienced significant variations in the degree of processing in the solar nebula. Comets contain a surprisingly high abundance of nebular solids formed or altered at high temperatures. Comet 81P/Wild 2 samples include 10-40 micron-sized, refractory Ca- Al-rich inclusion (CAI)-, chondrule-, and ameboid olivine aggregate (AOA)-like materials. The O isotopic compositions of these refractory materials are remarkably similar to their meteoritic counterparts, ranging from 5 percent enrichments in (sup 16) O to near-terrestrial values. Comet 81P/Wild 2 and CP-IDPs also contain abundant Mg-Fe crystalline and amorphous silicates whose O isotopic compositions are also consistent with Solar System origins. Unlike meteorites, that are dominated by locally-produced materials, comets appear to be composed of materials that were formed across a wide swath of the early protoplanetary disk.

A Focus on Pre Writing Strategies.

ERIC Educational Resources Information Center

McKay, Sandra

Composition instruction directed at native speakers of English has focused on the composed product rather than the composing process. The teaching of English as a second language (ESL) students has had a similar emphasis, with much classroom time devoted to sentence manipulation and usage exercises. Such exercises have little effectiveness in…

Exploring the Interpretative Platform: Composer and Pianist Thinking on Greenbaum's "First Light"

ERIC Educational Resources Information Center

Blom, Diana

2016-01-01

This study investigates the compositional and contextual thinking of composer, Stuart Greenbaum, and the preparatory thinking, and teaching experience of pianist, Yvonne Lau, in the preparation of the solo piano work, "First Light". Adopting a practice-informed interview approach with questions drawn from the researcher's own preparation…

Creative Thinking for 21st Century Composing Practices: Creativity Pedagogies across Disciplines

ERIC Educational Resources Information Center

Lee, Sohui; Carpenter, Russell

2015-01-01

In this article, the authors explore the corpus of literature on creative thinking and applied creativity in higher education to help composition teacher-scholars and writing center practitioners improve the application of creativity in written, visual, and multimodal composing practices. From studies of creative thinking investigated across…

Assessing a Collaborative Online Environment for Music Composition

ERIC Educational Resources Information Center

Biasutti, Michele

2015-01-01

The current pilot study tested the effectiveness of an e-learning environment built to enable students to compose music collaboratively. The participants interacted online by using synchronous and asynchronous resources to develop a project in which they composed a new music piece in collaboration. After the learning sessions, individual…

Identification of mineral compositions in some renal calculi by FT Raman and IR spectral analysis

NASA Astrophysics Data System (ADS)

Tonannavar, J.; Deshpande, Gouri; Yenagi, Jayashree; Patil, Siddanagouda B.; Patil, Nikhil A.; Mulimani, B. G.

2016-02-01

We present in this paper accurate and reliable Raman and IR spectral identification of mineral constituents in nine samples of renal calculi (kidney stones) removed from patients suffering from nephrolithiasis. The identified mineral components include Calcium Oxalate Monohydrate (COM, whewellite), Calcium Oxalate Dihydrate (COD, weddellite), Magnesium Ammonium Phosphate Hexahydrate (MAPH, struvite), Calcium Hydrogen Phosphate Dihydrate (CHPD, brushite), Pentacalcium Hydroxy Triphosphate (PCHT, hydroxyapatite) and Uric Acid (UA). The identification is based on a satisfactory assignment of all the observed IR and Raman bands (3500-400 cm- 1) to chemical functional groups of mineral components in the samples, aided by spectral analysis of pure materials of COM, MAPH, CHPD and UA. It is found that the eight samples are composed of COM as the common component, the other mineral species as common components are: MAPH in five samples, PCHT in three samples, COD in three samples, UA in three samples and CHPD in two samples. One sample is wholly composed of UA as a single component; this inference is supported by the good agreement between ab initio density functional theoretical spectra and experimental spectral measurements of both sample and pure material. A combined application of Raman and IR techniques has shown that, where the IR is ambiguous, the Raman analysis can differentiate COD from COM and PCHT from MAPH.

Identification of mineral compositions in some renal calculi by FT Raman and IR spectral analysis.

PubMed

Tonannavar, J; Deshpande, Gouri; Yenagi, Jayashree; Patil, Siddanagouda B; Patil, Nikhil A; Mulimani, B G

2016-02-05

We present in this paper accurate and reliable Raman and IR spectral identification of mineral constituents in nine samples of renal calculi (kidney stones) removed from patients suffering from nephrolithiasis. The identified mineral components include Calcium Oxalate Monohydrate (COM, whewellite), Calcium Oxalate Dihydrate (COD, weddellite), Magnesium Ammonium Phosphate Hexahydrate (MAPH, struvite), Calcium Hydrogen Phosphate Dihydrate (CHPD, brushite), Pentacalcium Hydroxy Triphosphate (PCHT, hydroxyapatite) and Uric Acid (UA). The identification is based on a satisfactory assignment of all the observed IR and Raman bands (3500-400c m(-1)) to chemical functional groups of mineral components in the samples, aided by spectral analysis of pure materials of COM, MAPH, CHPD and UA. It is found that the eight samples are composed of COM as the common component, the other mineral species as common components are: MAPH in five samples, PCHT in three samples, COD in three samples, UA in three samples and CHPD in two samples. One sample is wholly composed of UA as a single component; this inference is supported by the good agreement between ab initio density functional theoretical spectra and experimental spectral measurements of both sample and pure material. A combined application of Raman and IR techniques has shown that, where the IR is ambiguous, the Raman analysis can differentiate COD from COM and PCHT from MAPH. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation and Characterization of Graphene Oxide Paper

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

Dikin,D.; Stankovich, S.; Zimney, E.

2007-01-01

Free-standing paper-like or foil-like materials are an integral part of our technological society. Their uses include protective layers, chemical filters, components of electrical batteries or supercapacitors, adhesive layers, electronic or optoelectronic components, and molecular storage. Inorganic 'paper-like' materials based on nanoscale components such as exfoliated vermiculite or mica platelets have been intensively studied and commercialized as protective coatings, high-temperature binders, dielectric barriers and gas-impermeable membranes. Carbon-based flexible graphite foils composed of stacked platelets of expanded graphite have long been used in packing and gasketing applications because of their chemical resistivity against most media, superior sealability over a wide temperature range,more » and impermeability to fluids. The discovery of carbon nanotubes brought about bucky paper, which displays excellent mechanical and electrical properties that make it potentially suitable for fuel cell and structural composite applications. Here we report the preparation and characterization of graphene oxide paper, a free-standing carbon-based membrane material made by flow-directed assembly of individual graphene oxide sheets. This new material outperforms many other paper-like materials in stiffness and strength. Its combination of macroscopic flexibility and stiffness is a result of a unique interlocking-tile arrangement of the nanoscale graphene oxide sheets.« less

Preparation and characterization of graphene oxide paper.

PubMed

Dikin, Dmitriy A; Stankovich, Sasha; Zimney, Eric J; Piner, Richard D; Dommett, Geoffrey H B; Evmenenko, Guennadi; Nguyen, SonBinh T; Ruoff, Rodney S

2007-07-26

Free-standing paper-like or foil-like materials are an integral part of our technological society. Their uses include protective layers, chemical filters, components of electrical batteries or supercapacitors, adhesive layers, electronic or optoelectronic components, and molecular storage. Inorganic 'paper-like' materials based on nanoscale components such as exfoliated vermiculite or mica platelets have been intensively studied and commercialized as protective coatings, high-temperature binders, dielectric barriers and gas-impermeable membranes. Carbon-based flexible graphite foils composed of stacked platelets of expanded graphite have long been used in packing and gasketing applications because of their chemical resistivity against most media, superior sealability over a wide temperature range, and impermeability to fluids. The discovery of carbon nanotubes brought about bucky paper, which displays excellent mechanical and electrical properties that make it potentially suitable for fuel cell and structural composite applications. Here we report the preparation and characterization of graphene oxide paper, a free-standing carbon-based membrane material made by flow-directed assembly of individual graphene oxide sheets. This new material outperforms many other paper-like materials in stiffness and strength. Its combination of macroscopic flexibility and stiffness is a result of a unique interlocking-tile arrangement of the nanoscale graphene oxide sheets.

Relationships between Translation and Transcription Processes during fMRI Connectivity Scanning and Coded Translation and Transcription in Writing Products after Scanning in Children with and without Transcription Disabilities

PubMed Central

Wallis, Peter; Richards, Todd; Boord, Peter; Abbott, Robert; Berninger, Virginia

2018-01-01

Students with transcription disabilities (dysgraphia/impaired handwriting, n = 13 or dyslexia/impaired word spelling, n = 16) or without transcription disabilities (controls) completed transcription and translation (idea generating, planning, and creating) writing tasks during fMRI connectivity scanning and compositions after scanning, which were coded for transcription and translation variables. Compositions in both groups showed diversity in genre beyond usual narrative-expository distinction; groups differed in coded transcription but not translation variables. For the control group specific transcription or translation tasks during scanning correlated with corresponding coded transcription or translation skills in composition, but connectivity during scanning was not correlated with coded handwriting during composing in dysgraphia group and connectivity during translating was not correlated with any coded variable during composing in dyslexia group. Results are discussed in reference to the trend in neuroscience to use connectivity from relevant seed points while performing tasks and trends in education to recognize the generativity (creativity) of composing at both the genre and syntax levels. PMID:29600113

Protein nanoparticles are nontoxic, tuneable cell stressors.

PubMed

de Pinho Favaro, Marianna Teixeira; Sánchez-García, Laura; Sánchez-Chardi, Alejandro; Roldán, Mónica; Unzueta, Ugutz; Serna, Naroa; Cano-Garrido, Olivia; Azzoni, Adriano Rodrigues; Ferrer-Miralles, Neus; Villaverde, Antonio; Vázquez, Esther

2018-02-01

Nanoparticle-cell interactions can promote cell toxicity and stimulate particular behavioral patterns, but cell responses to protein nanomaterials have been poorly studied. By repositioning oligomerization domains in a simple, modular self-assembling protein platform, we have generated closely related but distinguishable homomeric nanoparticles. Composed by building blocks with modular domains arranged in different order, they share amino acid composition. These materials, once exposed to cultured cells, are differentially internalized in absence of toxicity and trigger distinctive cell adaptive responses, monitored by the emission of tubular filopodia and enhanced drug sensitivity. The capability to rapidly modulate such cell responses by conventional protein engineering reveals protein nanoparticles as tuneable, versatile and potent cell stressors for cell-targeted conditioning.

Stress Wave Propagation in Viscoelastic-Plastic Rock-Like Materials.

PubMed

Lang, Liu; Song, Ki-Il; Zhai, Yue; Lao, Dezheng; Lee, Hang-Lo

2016-05-17

Rock-like materials are composites that can be regarded as a mixture composed of elastic, plastic, and viscous components. They exhibit viscoelastic-plastic behavior under a high-strain-rate loading according to element model theory. This paper presents an analytical solution for stress wave propagation in viscoelastic-plastic rock-like materials under a high-strain-rate loading and verifies the solution through an experimental test. A constitutive equation of viscoelastic-plastic rock-like materials was first established, and then kinematic and kinetic equations were then solved to derive the analytic solution for stress wave propagation in viscoelastic-plastic rock-like materials. An experimental test using the SHPB (Split Hopkinson Pressure Bar) for a concrete specimen was conducted to obtain a stress-strain curve under a high-strain-rate loading. Inverse analysis based on differential evolution was conducted to estimate undetermined variables for constitutive equations. Finally, the relationship between the attenuation factor and the strain rate in viscoelastic-plastic rock-like materials was investigated. According to the results, the frequency of the stress wave, viscosity coefficient, modulus of elasticity, and density play dominant roles in the attenuation of the stress wave. The attenuation decreases with increasing strain rate, demonstrating strongly strain-dependent attenuation in viscoelastic-plastic rock-like materials.

The effect of fly ash and coconut fibre ash as cement replacement materials on cement paste strength

NASA Astrophysics Data System (ADS)

Bayuaji, R.; Kurniawan, R. W.; Yasin, A. K.; Fatoni, H. AT; Lutfi, F. M. A.

2016-04-01

Concrete is the backbone material in the construction field. The main concept of the concrete material is composed of a binder and filler. Cement, concrete main binder highlighted by environmentalists as one of the industry are not environmentally friendly because of the burning of cement raw materials in the kiln requires energy up to a temperature of 1450° C and the output air waste CO2. On the other hand, the compound content of cement that can be utilized in innovation is Calcium Hydroxide (CaOH), this compound will react with pozzolan material and produces additional strength and durability of concrete, Calcium Silicate Hydrates (CSH). The objective of this research is to explore coconut fibers ash and fly ash. This material was used as cement replacement materials on cement paste. Experimental method was used in this study. SNI-03-1974-1990 is standard used to clarify the compressive strength of cement paste at the age of 7 days. The result of this study that the optimum composition of coconut fiber ash and fly ash to substitute 30% of cement with 25% and 5% for coconut fibers ash and fly ash with similar strength if to be compared normal cement paste.

Stress Wave Propagation in Viscoelastic-Plastic Rock-Like Materials

PubMed Central

Lang, Liu; Song, KI-IL; Zhai, Yue; Lao, Dezheng; Lee, Hang-Lo

2016-01-01

Rock-like materials are composites that can be regarded as a mixture composed of elastic, plastic, and viscous components. They exhibit viscoelastic-plastic behavior under a high-strain-rate loading according to element model theory. This paper presents an analytical solution for stress wave propagation in viscoelastic-plastic rock-like materials under a high-strain-rate loading and verifies the solution through an experimental test. A constitutive equation of viscoelastic-plastic rock-like materials was first established, and then kinematic and kinetic equations were then solved to derive the analytic solution for stress wave propagation in viscoelastic-plastic rock-like materials. An experimental test using the SHPB (Split Hopkinson Pressure Bar) for a concrete specimen was conducted to obtain a stress-strain curve under a high-strain-rate loading. Inverse analysis based on differential evolution was conducted to estimate undetermined variables for constitutive equations. Finally, the relationship between the attenuation factor and the strain rate in viscoelastic-plastic rock-like materials was investigated. According to the results, the frequency of the stress wave, viscosity coefficient, modulus of elasticity, and density play dominant roles in the attenuation of the stress wave. The attenuation decreases with increasing strain rate, demonstrating strongly strain-dependent attenuation in viscoelastic-plastic rock-like materials. PMID:28773500

Mimicking the Humidity Response of the Plant Cell Wall by Using Two-Dimensional Systems: The Critical Role of Amorphous and Crystalline Polysaccharides.

PubMed

Niinivaara, Elina; Faustini, Marco; Tammelin, Tekla; Kontturi, Eero

2016-03-01

Of the composite materials occurring in nature, the plant cell wall is among the most intricate, consisting of a complex arrangement of semicrystalline cellulose microfibrils in a dissipative matrix of lignin and hemicelluloses. Here, a biomimetic, two-dimensional cellulose system of the cell wall structure is introduced where cellulose nanocrystals compose the crystalline portion and regenerated amorphous cellulose composes the dissipative matrix. Spectroscopic ellipsometry and QCM-D are used to study the water vapor uptake of several two-layer systems. Quantitative analysis shows that the vapor-induced swelling of these ultrathin films can be controlled by varying ratios of the chemically identical ordered and unordered cellulose components. Intriguingly, increasing the share of crystalline cellulose appeared to increase the vapor uptake but only in cases for which the interfacial area between the crystalline and amorphous area was relatively large and the thickness of an amorphous overlayer was relatively small. The results show that a biomimetic approach may occasionally provide answers as to why certain native structures exist.

Fabrication and characterization of bending and pressure sensors for a soft prosthetic hand

NASA Astrophysics Data System (ADS)

Rocha, Rui Pedro; Alhais Lopes, Pedro; de Almeida, Anibal T.; Tavakoli, Mahmoud; Majidi, Carmel

2018-03-01

We demonstrate fabrication, characterization, and implementation of ‘soft-matter’ pressure and bending sensors for a soft robotic hand. The elastomer-based sensors are embedded in a robot finger composed of a 3D printed endoskeleton and covered by an elastomeric skin. Two types of sensors are evaluated, resistive pressure sensors and capacitive pressure sensors. The sensor is fabricated entirely out of insulating and conductive rubber, the latter composed of polydimethylsiloxane (PDMS) elastomer embedded with a percolating network of structured carbon black (CB). The sensor-integrated fingers have a simple materials architecture, can be fabricated with standard rapid prototyping methods, and are inexpensive to produce. When incorporated into a robotic hand, the CB-PDMS sensors and PDMS carrier medium function as an ‘artificial skin’ for touch and bend detection. Results show improved response with a capacitive sensor architecture, which, unlike a resistive sensor, is robust to electromechanical hysteresis, creep, and drift in the CB-PDMS composite. The sensorized fingers are integrated in an anthropomorphic hand and results for a variety of grasping tasks are presented.

Composite fuel cell membranes

DOEpatents

Plowman, K.R.; Rehg, T.J.; Davis, L.W.; Carl, W.P.; Cisar, A.J.; Eastland, C.S.

1997-08-05

A bilayer or trilayer composite ion exchange membrane is described suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

Composite fuel cell membranes

DOEpatents

Plowman, Keith R.; Rehg, Timothy J.; Davis, Larry W.; Carl, William P.; Cisar, Alan J.; Eastland, Charles S.

1997-01-01

A bilayer or trilayer composite ion exchange membrane suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

Characterization of fly ash, slag and glass hull for the obtaining of vitreous materials

NASA Astrophysics Data System (ADS)

Ayala Valderrama, D. M.; Gómez Cuaspud, J. A.

2017-12-01

This article presents the structural and thermal characterization of fly ash, the waste from blast furnace slag and the glass hull, generated as common residues in industry, which cannot be recycled easily or destroyed in a simple and fast way. In the particular case of fly ash, at present are being used as a lightweight aggregate in the production of cement, concrete and additive in the production of glass and glass ceramics. As far as the slag and hull, are being used as additives for the asphalt and concretes, however its use still is restricted, reason why its use in alternative ways are necessary. Initially the chemical composition of residues was established, determining that the fly ashes contains SiO2, Al2O3 and Fe2O3 oxides; 90% of the total composition, was confirmed by X-ray diffraction analysis. As minor constituents, small percentages of Mg, P, S, K, Na and Ti were found. For the slag case, the phases of Fe3O4, Ca3Mg (SiO2)4 and Ca(MgAl)(Si,Al)2O6 were identified, observing the presence of amorphous phase higher than 94% of the total phase of the system. Meanwhile, the glass hull sample showed a higher percentage of 95% amorphicity, mainly identifying a weak signal associated with silicon oxide SiO2. The thermal analyses of the samples, exhibit a decrease in mass for samples between 25-1000°C was observed, which can be attributed to different physical-chemical events that occur in the materials. The heat flow for each sample is related with the removal of the water retained by the physisorption processes around 92-110°C in all cases. With this previous characterization of the precursors, a sample was composed using 70% fly ash, 10% slag and 20% of glass hull was composed and treated at 1200°C/1.5 hours, obtaining a dense black glassy material for potential applications in field of the glass ceramics.

Intelligent transportation systems infrastructure initiative

DOT National Transportation Integrated Search

1997-01-01

The three-quarter moving composite price index is the weighted average of the indices for three consecutive quarters. The Composite Bid Price Index is composed of six indicator items: common excavation, to indicate the price trend for all roadway exc...

The role of ocean phenomenon in music compositions

NASA Astrophysics Data System (ADS)

Liu, Chi-Min

2016-04-01

This is a preliminarily interdisciplinary study for exploring the elements of ocean phenomenon appearing in some compositions of classical music. The so-called ocean phenomenon contain wave conditions, climate change, coastal landform, and other natural events around or over the sea. In some music compositions, it is apparent that natural phenomenon over the sea influence the composers' moods and the music pieces they composed. In this poster, some music compositions in the 19th and the early 20th centuries will be introduced to demonstrate the relation between ocean and music works. These works include Meeresstille by Schubert, Étude Op.25 No.12 by Chopin, Fingal's Cave Overture by Mendelssohn, Der Fliegende Holländer by Wagner and La Mer by Debussy. In addition, present idea may give a novel way for music teachers to elucidate the knowledge of ocean science in classes.