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1

Determination of Chemical Composition, Mineral Contents,and Protein Quality of Poultry By-Product Meal  

Microsoft Academic Search

2 Abstract: In order to study the chemical composition, mineral contents and protein quality of poultry by- product meal (PBPM), 10 composed samples of PBPM produced in Iran were provided during two months sampling period from rendering units of three industrial poultry slaughter-houses. The proximate analysis showed that the average dry matter (DM), ether extract (EE), crude protein (CP), crude

Hossein Jahanian Najafabadi; Hassan Nassiri Moghaddam; Javad Pourreza; Feridoon Eftekhar Shahroudi; Abolghasem Golian

2007-01-01

2

Minerals by Chemical Composition  

NSDL National Science Digital Library

This interactive periodic table displays a listing of minerals by element, sorted by percent of the element. Clicking on a symbol on the table leads users to information on the element (atomic mass and number, name origin, year of discovery, and a brief description), and to a table listing each mineral known to contain the element in decreasing order by percentage. Each mineral name in the table is linked to additional information on the mineral, such as formula and composition, images, crystallography, physical properties, and many others.

3

Chemical composition, mineral content and cholesterol levels of some regular  

E-print Network

Note Chemical composition, mineral content and cholesterol levels of some regular and reduced from cow's milk, were analyzed for basic nutrients (water, protein, fat, ash and lactose), cholesterol-1 . Cholesterol strongly correlated with fat content and an increase in cholesterol/fat ratios

Boyer, Edmond

4

Nondestructive activation analysis of sample of lunar surface material returned by Luna 16 automatic station. [chemical composition  

NASA Technical Reports Server (NTRS)

The composition of a sample of lunar surface material returned by the Luna 16 automatic station from the Sea of Fertility was studied, using nondestructive activation analysis. The structure of the returned surface material is inhomogeneous; the surficial material is thin, quite homogeneous, and the granularity increases with depth. Based on grain size, the sample was separated into five zones. The activation analysis was conducted on a sample taken from the friable surficial layer, zone A. The content of Al, Mn, Na, Cr, Co, Fe, and Sc was determined by nondestructive activation analysis of the sample. In determining Cr, Co, Fe, and Sc, the sample was irradiated for 24 hours and cooled for 10 days. Gamma spectra of the samples were recorded with a semiconductor Ge(Li)-detector and a multichannel analyzer, and measurement data were processed with an electronic computer.

Chayko, M.; Sabo, E.

1974-01-01

5

Development of chemical vapor composites, CVC materials. Final report  

SciTech Connect

Industry has a critical need for high-temperature operable ceramic composites that are strong, non-brittle, light weight, and corrosion resistant. Improvements in energy efficiency, reduced emissions and increased productivity can be achieved in many industrial processes with ceramic composites if the reaction temperature and pressure are increased. Ceramic composites offer the potential to meet these material requirements in a variety of industrial applications. However, their use is often restricted by high cost. The Chemical Vapor composite, CVC, process can reduce the high costs and multiple fabrication steps presently required for ceramic fabrication. CVC deposition has the potential to eliminate many difficult processing problems and greatly increase fabrication rates for composites. With CVC, the manufacturing process can control the composites` density, microstructure and composition during growth. The CVC process: can grow or deposit material 100 times faster than conventional techniques; does not require an expensive woven preform to infiltrate; can use high modulus fibers that cannot be woven into a preform; can deposit composites to tolerances of less than 0.025 mm on one surface without further machining.

NONE

1998-10-05

6

Influence of chemical composition of soils on the galanthamine content in Levcojum aestivum  

Microsoft Academic Search

The elemental composition of seven soils of the main geographical regions in Bulgaria for the growth of Leucojum aestivum L. was determined. It was found that a relationship exists between the galanthamine content of the plant and the chemical composition of the soil. These results indicate that galanthamine bio? synthesis could be controlled by the soil fertility level.

N. I. Gorinova; A. I. Atanassov; D. V. Stojanov; J. Tencheva

1993-01-01

7

Composite Materials  

NASA Technical Reports Server (NTRS)

Langley Research Center researchers invented an advanced polymer, a chemical compound formed by uniting many small molecules to create a complex molecule with different chemical properties. The material is a thermoplastic polyimide that resists solvents. Other polymers of this generic type are soluble in solvents, thus cannot be used where solvents are present. High Technology Services (HTS), Inc. licensed technology and is engaged in development and manufacture of high performance plastics, resins and composite materials. Techimer Materials Division is using technology for composite matrix resins that offer heat resistance and protection from radiation, electrical and chemical degradation. Applications of new polymer include molding resins, adhesives and matrix resins for fiber reinforced composites.

1988-01-01

8

Nanoporous Copper-Silicon Composite Prepared by Chemical Dealloying as Anode Material for Lithium-Ion Batteries  

NASA Astrophysics Data System (ADS)

A novel and simple method has been developed to prepare the Cu-Si composite as anode material for lithium-ion batteries. Nanoporous Cu-Si composite with pore sizes of 1 30 nm was prepared by dealloying the melt-spun Al-Cu-Si-Ce ribbons in a 5 wt.% HCl solution. Electrochemical tests revealed that the nanoporous Cu-Si electrodes exhibited highly reversible capacity of 2317 mAhg-1 and retained a capacity of 1030 mAhg-1 over 20 cycles. The excellent electrochemical performance is attributed to the unique porous structure of the Cu-Si composite. Our results demonstrate that this novel composite is a promising anode candidate for high-capacity rechargeable lithium-ion batteries.

Li, Guijing; Song, Yanyan; Zhang, Linping; Wei, Xin; Song, Xiaoping; Sun, Zhanbo

2013-06-01

9

Composite-Material Tanks with Chemically Resistant Liners  

NASA Technical Reports Server (NTRS)

Lightweight composite-material tanks with chemically resistant liners have been developed for storage of chemically reactive and/or unstable fluids . especially hydrogen peroxide. These tanks are similar, in some respects, to the ones described in gLightweight Composite-Material Tanks for Cryogenic Liquids h (MFS-31379), NASA Tech Briefs, Vol. 25, No. 1 (January, 2001), page 58; however, the present tanks are fabricated by a different procedure and they do not incorporate insulation that would be needed to prevent boil-off of cryogenic fluids. The manufacture of a tank of this type begins with the fabrication of a reusable multisegmented aluminum mandrel in the shape and size of the desired interior volume. One or more segments of the mandrel can be aluminum bosses that will be incorporated into the tank as end fittings. The mandrel is coated with a mold-release material. The mandrel is then heated to a temperature of about 400 F (approximately equal to 200 C) and coated with a thermoplastic liner material to the desired thickness [typically approxiamtely equal to 15 mils (approximately equal to 0.38 mm)] by thermal spraying. In the thermal-spraying process, the liner material in powder form is sprayed and heated to the melting temperature by a propane torch and the molten particles land on the mandrel. The sprayed liner and mandrel are allowed to cool, then the outer surface of the liner is chemically and/or mechanically etched to enhance bonding of a composite overwrap. The etched liner is wrapped with multiple layers of an epoxy resin reinforced with graphite fibers; the wrapping can be done either by manual application of epoxy-impregnated graphite cloth or by winding of epoxy-impregnated filaments. The entire assembly is heated in an autoclave to cure the epoxy. After the curing process, the multisegmented mandrel is disassembled and removed from inside, leaving the finished tank. If the tank is to be used for storing hydrogen peroxide, then the liner material should be fluorinated ethylene/propylene (FEP), and one or more FEP O ring(s) should be used in the aluminum end fitting(s). This choice of materials is dictated by experimental observations that pure aluminum and FEP are the only materials suitable for long-term storage of hydrogen peroxide and that other materials tend to catalyze the decomposition of hydrogen peroxide to oxygen and water. Other thermoplastic liner materials that are suitable for some applications include nylon 6 and polyethylene. The processing temperatures for nylon 6 are lower than those for FEP. Nylon 6 is compatible with propane, natural gas, and other petroleum-based fuels. Polyethylene is compatible with petroleum- based products and can be used for short-term storage of hydrogen peroxide.

DeLay, Thomas K.

2004-01-01

10

Chemical Composition of Wild-2 Dust Collected by Stardust  

NASA Astrophysics Data System (ADS)

The Stardust spacecraft collected dust from Comet Wild-2 in two forms: material distributed along tracks in aerogel capture cells and residue in impact craters. To analyze the chemical composition of these samples the tracks produced in the aerogel were extracted as keystones containing complete tracks. Twenty-six tracks were analyzed using an X-Ray Microprobe, providing x-ray fluorescence chemical analysis for elements having K-lines at energies high enough to permit escape from the overlying aerogel (S and the heavier elements, including the moderately-volatile trace elements Cu, Zn, and Ga). Two of these tracks were then split open, exposing the interior for analysis by TOF-SIMS (which allowed detection of the lighter elements, e.g., Mg and Al). Neither Si nor O could be determined for samples captured in the aerogel, since these are the major elements in the aerogel itself. The residue in craters in the Al-foil were analyzed by SEM-EDX and TOF-SIMS. The crater residues provide information on the important light elements (Mg and Si). By combining the results from the craters and the tracks, a comprehensive chemical analysis of the Wild-2 dust was possible. Preliminary Examination of the material indicates that: 1) For particles collected in the aerogel, a significant fraction of the incident mass is frequently deposited along the entry track, suggesting the individual Wild-2 dust particles that hit the aerogel were relatively weak aggregates. 2) The chemical composition of the terminal particle in the track is frequently significantly different from the composition of the material deposited along the track, 3) Most of the elements measured show variations in their Fe-normalized abundances of more than two orders-of-magnitude in both the terminal particles and the material deposited along track walls, indicating that the Wild-2 dust is compositionally heterogeneous at the size scale of the largest particles analyzed, not simply a well-mixed aggregate of sub-micron grains, 4) The mean content of the refractory, rock-forming elements (Mg, Ca, Si, Cr, Fe, and Ni) averaged over the whole tracks and/or the crater residues in the Wild-2 grains are approximately chondritic, and, 5) There is an apparent enrichment over CI in some of the moderately-volatile minor elements (Cu, Zn, and Ga) in the Wild-2 dust.

Flynn, G. J.

2006-12-01

11

Predicting corn digestible and metabolizable energy content from its chemical composition in growing pigs  

PubMed Central

Background The nutrient composition of corn is variable. To prevent unforeseen reductions in growth performance, grading and analytical methods are used to minimize nutrient variability between calculated and analyzed values. This experiment was carried out to define the sources of variation in the energy content of corn and to develop a practical method to accurately estimate the digestible energy (DE) and metabolisable energy (ME) content of individual corn samples for growing pigs. Twenty samples were taken from each of five provinces in China (Jilin, Hebei, Shandong, Liaoning, and Henan) to obtain a range of quality. Results The DE and ME contents of the 100 corn samples were measured in 35.3?±?1.92 kg growing pigs (six pigs per corn sample). Sixty corn samples were used to build the prediction model; the remaining forty samples were used to test the suitability of these models. The chemical composition of each corn sample was determined, and the results were used to establish prediction equations for DE or ME content from chemical characteristics. The mean DE and ME content of the 100 samples were 4,053 and 3,923 kcal/kg (dry matter basis), respectively. The physical characteristics were determined, as well, and the results indicated that the bulk weight and 1,000-kernel weight were not associated with energy content. The DE and ME values could be accurately predicted from chemical characteristics. The best fit equations were as follows: DE, kcal/kg of DM?=?1062.68?+?(49.72?×?EE)?+?(0.54?×?GE)?+?(9.11?×?starch), with R2?=?0.62, residual standard deviation (RSD)?=?48 kcal/kg, and P?content of corn, describes the factors that influence this variation, and presents equations based on chemical measurements that may be used to predict the DE and ME content of individual corn samples. PMID:24521251

2014-01-01

12

Influence of the composition of the initial mixtures on the chemical composition, physicochemical properties and humic-like substances content of composts.  

PubMed

The influence of the proportion of C- and N-rich raw materials (initial C/N ratio) and bulking agent on the chemical functional groups composition, humic-like substances (HS-like) content and physicochemical properties of composts was assessed. To achieve these goals, seven initial mixtures (BA1-6 and C1) of dog food (N-rich raw material) were composted with wheat flour (C-rich raw material). Composts were analyzed in terms of chemical functional groups, physicochemical, maturity and stability parameters. The C-rich raw material favored the formation of oxidized organic matter (OM) during the composting process, as suggested by the variation of the ratios of the peaks intensity of FT-IR spectra, corresponding to a decrease of the polysaccharides and an increase of aromatic and carboxyl-containing compounds. However, although with high proportion of C-rich raw material, mixtures with low initial C/N seems to have favored the accumulation of partially oxidized OM, which may have contributed to high electrical conductivity values in the final composts. Therefore, although favoring the partial transformation of OM into stabilized HS-like, initial mixtures with high proportion of C-rich raw material but with low initial C/N led to unstable composts. On the other hand, as long as a high percentage of bulking agent was used to promote the structure of biomass and consequently improve of the aeration conditions, low initial C/N was not a limiting factor of OM oxidation into extractable stabilized humic-like acids. PMID:24119374

Silva, Maria Elisabete F; de Lemos, Luís Teixeira; Nunes, Olga C; Cunha-Queda, Ana Cristina

2014-01-01

13

Identification of Flavonoid Content and Chemical Composition of the Essential Oils of Moroccan Herbs: Myrtle (Myrtus communis L.), Rockrose (Cistus ladanifer L.) and Montpellier cistus (Cistus monspeliensis L.)  

Microsoft Academic Search

The aim of this work was to determine the polyphenol content and chemical composition of the essential oils of some Moroccan herbs: myrtle (Myrtus communis L.), rockrose (Cistus ladanifer L.) and montpellier cistus (Cistus monspeliensis L.). The polyphenols were analyzed and identified by HPLC and the essential oils were chemically analyzed and identified by GC\\/MS. The principal components of myrtle

Manuel Viuda-Martos; Esther Sendra; José A. Pérez-Alvarez; Juana Fernández-López; Mahassine Amensour; Jamal Abrini

2011-01-01

14

Analysis and chemical composition of larnite-rich ultrarefractory materials  

Microsoft Academic Search

Larnite (b-Ca2SiO4) is a rare, little known compound. However, despite its scarcity, larnite is found in different natural settings, almost always under thermodynamic conditions of around 0.2–1kbar and 1000–1100°C. Larnite can also be formed artificially, especially during the synthesis of high technology refractory and ceramic materials, and as a mineral component of some industrial slags and portland cements. This work

J Mart??nez-Fr??as; R. Benito; G. Wilson; A. Delgado; T. Boyde; K Marti

2004-01-01

15

The effects of space radiation on a chemically modified graphite-epoxy composite material  

NASA Technical Reports Server (NTRS)

The effects of the space environment on the engineering properties and chemistry of a chemically modified T300/934 graphite-epoxy composite system are characterized. The material was subjected to 1.0 x 10 to the 10th power rads of 1.0 MeV electron irradiation under vacuum to simulate 30 years in geosynchronous earth orbit. Monotonic tension tests were performed at room temperature (75 F/24 C) and elevated temperature (250 F/121 C) on 4-ply unidirectional laminates. From these tests, inplane engineering and strength properties (E sub 1, E sub 2, Nu sub 12, G sub 12, X sub T, Y sub T) were determined. Cyclic tests were also performed to characterize energy dissipation changes due to irradiation and elevated temperature. Large diameter graphite fibers were tested to determine the effects of radiation on their stiffness and strength. No significant changes were observed. Dynamic-mechanical analysis demonstrated that the glass transition temperature was reduced by 50 F(28 C) after irradiation. Thermomechanical analysis showed the occurrence of volatile products generated upon heating of the irradiated material. The chemical modification of the epoxy did not aid in producing a material which was more radiation resistant than the standard T300/934 graphite-epoxy system. Irradiation was found to cause crosslinking and chain scission in the polymer. The latter produced low molecular weight products which plasticize the material at elevated temperatures and cause apparent material stiffening at low stresses at room temperature.

Reed, S. M.; Herakovich, C. T.; Sykes, G. F.

1986-01-01

16

Relative toxicity of pyrolysis gases from materials - Effects of chemical composition and test conditions  

NASA Technical Reports Server (NTRS)

Relative toxicity test data on 270 materials are presented, based on test procedures developed at the University of San Francisco. The effects of chemical composition, using data on 13 types of synthetic polymers and eight types of fabrics, are discussed. Selected materials were evaluated using nine test conditions with the USF method, and using methods developed at the FAA Civil Aeromedical Institute, Douglas Aircraft Company and San Jose State University.

Hilado, C. J.; Cumming, H. J.

1978-01-01

17

Effects of intra- and inter-laminar resin content on the mechanical properties of toughened composite materials  

NASA Technical Reports Server (NTRS)

Composite materials having multiphase toughened matrix systems and laminate architectures characterized by resin-rich interlaminar layers (RIL) have been the subject of much recent attention. Such materials are likely to find applications in thick compressively loaded structures such as the keel area of commercial aircraft fuselages. The effects of resin content and its interlaminar and intralaminar distribution on mechanical properties were investigated with test and analysis of two carbon-epoxy systems. The RIL was found to reduce the in situ strengthening effect for matrix cracking in laminates. Mode 2 fracture toughness was found to increase with increasing RIL thickness over the range investigated, and Mode 1 interlaminar toughness was negligibly affected. Compressive failure strains were found to increase with increasing resin content for specimens having no damage, holes, and impact damage. Analytical tools for predicting matrix cracking of off-axis plies and damage tolerance in compression after impact (CAI) were successfully applied to materials with RIL.

Grande, Dodd H.; Ilcewicz, Larry B.; Avery, William B.; Bascom, Willard D.

1991-01-01

18

Damage detection in composite materials by FBGs  

NASA Astrophysics Data System (ADS)

Embedded fiber Bragg gratings (FBGs) are sensitive to changes of near strain fields in a composite host monolithic structure, typical of aircraft airframes. FBGs have been embedded in different configurations (a typical position is the skin -- stiffener interface in a monolithic structure) for detecting events associated to damage occurrence. Thus, it is possible to think in FBGs not only as strain sensors, in a classical load monitoring configuration, but as a part of a structural health monitoring (SHM) system in composite structures dimensioned following damage tolerance criteria.

Menendez, Jose M.; Munoz, Pedro; Pintado, J. M.; Guemes, Alfredo

2004-06-01

19

Molten salts\\/ceramic-foam matrix composites by melt infiltration method as energy storage material  

Microsoft Academic Search

A new type of high temperature energy storage material was obtained through the melt infiltration method, using compounding\\u000a SiC ceramic foam as matrix and Na2SO4 as phase change material. The resulting composite material was measured by XRD, SEM, TG-DSC methods. The experimental results\\u000a indicate that the composite is composed of silicon carbide, sodium sulfate and square quartz, and no chemical

Jianfeng Wu; Jian Li; Xiaohong Xu; Lanfang Yang; Jufang Wu; Fang Zhao; Chuanguo Li

2009-01-01

20

Fracture analysis of composite materials by using photoelastic technique  

SciTech Connect

In this paper analytical equations have been derived for the determination of strain energy density factor (S-factor) and damage energy density factor (Z-factor) in composite materials. Dilatational and distortional energy density factors are discussed. Applications of stress-optical law in composite fracture analysis are studied. Equations to determine stress intensity factors in composite structure by using photoelastic coating techniques are also derived. The technique and equations introduced in this paper can be effectively applied in complicated composite structure for fracture analysis. They are specially useful for solving engineering problems in which no theoretical results are available.

Zhang, S.Q.; Wang, J.; Zu, J.B.; Sun, H.

1993-12-31

21

Preparation and characterization of ceramic composites and coatings by chemical vapor deposition and chemical vapor infiltration  

Microsoft Academic Search

Chemical vapor deposition or chemical vapor infiltration is a deposition process in which a solid phase is produced and condensed onto a substrate via chemical reaction of gases. Ceramic composites, Si\\/SiC, as well as coatings, Ti, TiN, C, W were produced by using this technique. Several characterization methods, including SEM, XRD, AES, XPS, and optical microscopy, were employed to investigate

Hwan; Luchen

1990-01-01

22

TGA-DTA and chemical composition study of raw material of Bikaner region for electrical porcelain  

NASA Astrophysics Data System (ADS)

Porcelains are vitrified and a fine grained ceramic product, used either glazed or unglazed and is often manufactured from a tri-axial body mix of clays, quartz and alkaline feldspar. Physical properties associated with porcelain include those of permeability, high strength, hardness, glassiness, durability, whiteness, translucence, resonance, brittleness, high resistance to the passage of electricity, high resistance to thermal shock and high elasticity[1,2]. Porcelain insulators are made from three raw materials; clay; feldspar and quartz. For porcelain manufacture the clay is categorized in two groups; ball clay and kaolin, each of which plays an important role, either in the preparation of the product or in the properties of the finished products. The following research highlights the importance that suits these materials for their contributions to the final properties of the product. Keeping this view a TGA-DTA and chemical composition of these raw materials were observed and these materials are found suitable for production of Electrical Porcelain.

Tak, S. K.; Shekhawat, M. S.; Mangal, R.

2013-06-01

23

The chemical composition and energy content of the energetic cosmic radiation  

NASA Technical Reports Server (NTRS)

A brief survey is made of our present knowledge of the composition and energy spectra of the primary cosmic radiation. The total energy carried by all forms of cosmic radiation that have appreciable penetrability into matter has been evaluated.

Waddington, C. J.

1972-01-01

24

Structure and chemical composition of the dentin-enamel junction analyzed by Confocal Raman Microscopy  

NASA Astrophysics Data System (ADS)

The structure and chemical composition of the human dentin-enamel junction (DEJ) was studied using confocal Raman microscopy - a chemical imaging technique. Slices of non-fixed, sound teeth were prepared with an Isomet diamond saw and scanned with Witec Alpha300R system. The combination of different characteristics peaks of phosphate, carbonate and organic matrix (respectively 960, 1072 and 1545 cm-1), generates images representing the chemical composition of the DEJ area. Images are also calculated using peak ratios enabling precise determination of the chemical composition across the DEJ. Then, with two characterized peaks, different pictures are calculated to show the ratio of two components. The images of the spatial distribution of mineral phosphate (960cm-1) to organic matrix (1545 cm-1) ratios, mineral carbonates (1072cm-1) to mineral phosphate ratios; and mineral carbonates to organic matrix ratios were reconstructed. Cross sectional and calculated graphic profile show the variations of the different chemical component ratios through the enamel and the dentin. Phosphate to organic ratio shows an accumulation of organic material under the enamel surface. The cross sectional profile of these pictures shows a high phosphate content compared to enamel in the vicinity of the DEJ. The Confocal Raman imaging technique can be used to further provide full chemical imaging of tooth, particularly of the whole DEJ and to study enamel and dentin decay.

Desoutter, A.; Salehi, H.; Slimani, A.; Marquet, P.; Jacquot, B.; Tassery, H.; Cuisinier, F. J. G.

2014-02-01

25

Aqueous fluid composition in CI chondritic materials: Chemical equilibrium assessments in closed systems  

NASA Astrophysics Data System (ADS)

Solids of nearly solar composition have interacted with aqueous fluids on carbonaceous asteroids, icy moons, and trans-neptunian objects. These processes altered mineralogy of accreted materials together with compositions of aqueous and gaseous phases. We evaluated chemistry of aqueous solutions coexisted with CI-type chondritic solids through calculations of chemical equilibria in closed water-rock-gas systems at different compositions of initial fluids, water/rock mass ratios (0.1-1000), temperatures (<350 °C), and pressures (<2 kbars). The calculations show that fluid compositions are mainly affected by solubilities of solids, the speciation of chlorine in initial water-rock mixtures, and the occurrence of Na-bearing secondary minerals such as saponite. The major species in modeled alkaline solutions are Na+, Cl-, CO32-,HCO3-, K+, OH-, H2, and CO2. Aqueous species of Mg, Fe, Ca, Mn, Al, Ni, Cr, S, and P are not abundant in these fluids owing to low solubility of corresponding solids. Typical NaCl type alkaline fluids coexist with saponite-bearing mineralogy that usually present in aqueously altered chondrites. A common occurrence of these fluids is consistent with the composition of grains emitted from Enceladus. Na-rich fluids with abundant CO32-,HCO3-, and OH- anions coexist with secondary mineralogy depleted in Na. The Na2CO3 and NaHCO3 type fluids could form via accretion of cometary ices. NaOH type fluids form in reduced environments and may locally occur on parent bodies of CR carbonaceous chondrites. Supposed melting of accreted HCl-bearing ices leads to early acidic fluids enriched in Mg, Fe and other metals, consistent with signs of low-pH alteration in chondrites. Neutralization of these solutions leads to alkaline Na-rich fluids. Sulfate species have negligible concentrations in closed systems, which remain reduced, especially at elevated pressures created by forming H2 gas. Hydrogen, CO2, and H2O dominate in the gaseous phase, though the abundance of methane cannot be fairly estimated.

Zolotov, Mikhail Yu.

2012-08-01

26

Composite Materials  

NASA Technical Reports Server (NTRS)

Composites are lighter and stronger than metals. Aramid fibers like Kevlar and Nomex were developed by DuPont Corporation and can be combined in a honeycomb structure which can give an airplane a light, tough structure. Composites can be molded into many aerodynamic shapes eliminating rivets and fasteners. Langley Research Center has tested composites for both aerospace and non-aerospace applications. They are also used in boat hulls, military shelters, etc.

1985-01-01

27

Gaining improved chemical composition by exploitation of Compton-to-Rayleigh intensity ratio in XRF analysis.  

PubMed

The high specificity of the coherent (Rayleigh), as well as incoherent (Compton) X-ray scattering to the mean atomic number of a specimen to be analyzed by X-ray fluorescence (XRF), is exploited to gain more information on the chemical composition. Concretely, the evaluation of the Compton-to-Rayleigh intensity ratio from XRF spectra and its relation to the average atomic number of reference materials via a calibration curve can reveal valuable information on the elemental composition complementary to that obtained from the reference-free XRF analysis. Particularly for matrices of lower mean atomic numbers, the sensitivity of the approach is so high that it can be easily distinguished between specimens of mean atomic numbers differing from each other by 0.1. Hence, the content of light elements which are "invisible" for XRF, particularly hydrogen, or of heavier impurities/additives in light materials can be calculated "by difference" from the scattering calibration curve. The excellent agreement between such an experimental, empirical calibration curve and a synthetically generated one, on the basis of a reliable physical model for the X-ray scattering, is also demonstrated. Thus, the feasibility of the approach for given experimental conditions and particular analytical questions can be tested prior to experiments with reference materials. For the present work a microfocus X-ray source attached on an SEM/EDX (scanning electron microscopy/energy dispersive X-ray spectroscopy) system was used so that the Compton-to-Rayleigh intensity ratio could be acquired with EDX spectral data for improved analysis of the elemental composition. PMID:24950635

Hodoroaba, Vasile-Dan; Rackwitz, Vanessa

2014-07-15

28

Soybean seed protein and oil contents and fatty acid composition adjustments by drought and temperature  

Microsoft Academic Search

Environmental stress during soybean [Glycine max (L.) Merr.] seed fill can alter the chemical composition of the seed and reduce yield, viability, and vigor. The effect of\\u000a drought and high air temperature (AT) on soybean seed protein and oil contents have not been reported. The objective of this\\u000a study was to characterize the protein and oil contents and fatty acid

D. L. Dornbos; R. E. Mullen

1992-01-01

29

(210)Pb content in natural gas pipeline residues ("black-powder") and its correlation with the chemical composition.  

PubMed

The present work was carried out to assess the (210)Pb content in "black-powder" found in pigging operations on gas pipelines in Brazil, in particular, on the Campos Basin gas pipeline. Additionally, the chemical composition of such deposits was determined and an eventual correlation with (210)Pb concentration evaluated. Typical "black-powder" generated in the natural gas pipeline from Campos Basin oilfield contains mainly iron oxide ( approximately 81%) and residual organic matter ( approximately 9%). The (210)Pb content ranges from 4.9 to 0.04k Bqkg(-1) and seems to be inversely correlated with the distance to the platforms. On the other hand, (226)Ra concentration is higher on the pipeline branch between the platform and the onshore installations. (228)Ra was only observed in few samples, in particular, in the samples with the highest (226)Ra content. PMID:15885858

Godoy, José Marcus; Carvalho, Franciane; Cordilha, Aloisio; Matta, Luiz Ernesto; Godoy, Maria Luiza

2005-01-01

30

A new method to quantitatively evaluate the chemical composition of waterlogged wood by means of attenuated total reflectance Fourier transform infrared (ATR FT-IR) measurements carried out on wet material.  

PubMed

Wood degradation in waterlogged conditions, although slow, is relevant in some specific contexts, such as in the case of cultural heritage preservation (e.g., ancient shipwrecks found under the water table). This decay process induces the selective depletion of the biopolymers constituting wood cell walls and mainly of their structural polysaccharides (both cellulose and hemicelluloses). Assessment of residual composition of cell walls is normally carried out using conventional chemical analyses, which, however, require elevated amounts of material. The present work reports on a new approach to quantitatively determine the residual chemical composition of wood (in terms of amount of lignin and holocellulose) and therefore its extent of degradation. This was accomplished by acquiring attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectra on material still in waterlogged conditions, which was simply placed in optical contact with the ATR crystal. Data for the calibration set were obtained by means of wet analyses, and the calibration model was based on multivariate statistical analysis through partial least square regression. Acquired spectra showed signals higher and better resolved than for dry wood. Calibration was selected after comparing two different normalization procedures and after processing signals of two different spectral ranges. Furthermore, the exclusion of some outliers led to a substantial improvement in the error parameters (R(2) and root mean square error of cross validation) associated with the calibration model, thus allowing for the selection of the best model. The stability of this best model was also established by means of the leave-more-out method. Finally, a procedure of external validation confirmed that the proposed model also could be applied to similar (for instance, belonging to Pinaceae) wood remains from other excavations. PMID:23643045

Pizzo, Benedetto; Pecoraro, Elisa; Macchioni, Nicola

2013-05-01

31

Permeation of glove materials by physiologically harmful chemicals.  

PubMed

The breakthrough times and permeation rates of 1,4-dichloro-2-butene, benzene, carbon tetrachloride, and 2-chloro-1,3-butadiene for eleven commercially available gloves were determined. Four methods of determining the breakthough time and permeation rate were evaluated. A wide variation in the glove material thickness and protection time was found showing that the adequate protection time can only be determined by testing the proposed glove with the chemicals to be handled. PMID:525613

Williams, J R

1979-10-01

32

Laser-induced breakdown spectroscopy (LIBS) technique for the determination of the chemical composition of complex inorganic materials  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy (LIBS) is a fast, fully optical method, that needs little or no sample preparation. In this technique qualitative and quantitative analysis is based on comparison. The determination of composition is generally based on the construction of a calibration curve namely the LIBS signal versus the concentration of the analyte. Typically, to calibrate the system, certified reference materials with known elemental composition are used. Nevertheless, such samples due to differences in the overall composition with respect to the used complex inorganic materials can influence significantly on the accuracy. There are also some intermediate factors which can cause imprecision in measurements, such as optical absorption, surface structure, thermal conductivity etc. This paper presents the calibration procedure performed with especially prepared pellets from the tested materials, which composition was previously defined. We also proposed methods of post-processing which allowed for mitigation of the matrix effects and for a reliable and accurate analysis. This technique was implemented for determination of trace elements in industrial copper concentrates standardized by conventional atomic absorption spectroscopy with a flame atomizer. A series of copper flotation concentrate samples was analyzed for contents of three elements, that is silver, cobalt and vanadium. It has been shown that the described technique can be used to qualitative and quantitative analyses of complex inorganic materials, such as copper flotation concentrates.

?azarek, ?ukasz; Anto?czak, Arkadiusz J.; Wójcik, Micha? R.; Kozio?, Pawe? E.; Stepak, Bogusz; Abramski, Krzysztof M.

2014-08-01

33

/Al-4Cu Composite Material Produced by Squeeze Casting Method  

NASA Astrophysics Data System (ADS)

The wear behavior of a weight fraction of particles with up to 30 wt.% in situ AlB2 flakes reinforced in Al-4Cu matrix alloy composites and fabricated by a squeeze casting method was investigated in a pin-on-disk abrasion test instrument against different SiC abrasives at room conditions. Wear tests were performed under the load of 10 N against SiC abrasive papers of 80, 100, and 120 mesh grits. The effects of sliding speed, AlB2 flake content, and abrasive grit sizes on the abrasive wear properties of the matrix alloy and composites have been evaluated. The main wear mechanisms were identified using an optical microscope. The results showed that in situ AlB2 flake reinforcement improved the abrasion resistance against all the abrasives used, and the abrasive wear resistance decreased with an increase in the sliding speed and the abrasive grit size. The wear resistances of the composites were considerably bigger than those of the matrix alloy and increased with increases in in situ AlB2 flake contents.

Ficici, Ferit

2014-05-01

34

Composite thin film materials on the basis of silver nanostructures on polymer matrix by methods of chemical metallization and self-assembling  

NASA Astrophysics Data System (ADS)

The techniques of formation of thin metallic coatings by deposition of silver nanoparticles (NPs) from solution onto the surface of glass and silicon substrates modified by polyelectrolytes were developed. The possibilities of the adsorption of individual silver particles, as well as creation of continuous films on their basis, were shown. The transmission, absorption and reflection spectra of obtained coatings were investigated. The most promising structure for metamaterials creation from the list of formed one was determined—solid thin film of Ag NPs on a glass substrate modified by polyethylenimine.

Skoptsov, Evgeniy; Agabekov, Vladimir; Binhussain, Mohammed A.; Egorov, Dmitriy; Ropot, Piotr

2014-08-01

35

Radon diffusion coefficients in 360 waterproof materials of different chemical composition.  

PubMed

This paper summarises the results of radon diffusion coefficient measurements in 360 common waterproof materials available throughout Europe. The materials were grouped into 26 categories according to their chemical composition. It was found that the diffusion coefficients of materials used for protecting houses against radon vary within eight orders from 10(-15) to 10(-8) m(2) s(-1). The lowest values were obtained for bitumen membranes with an Al carrier film and for ethylene vinyl acetate membranes. The highest radon diffusion coefficient values were discovered for sodium bentonite membranes, rubber membranes made of ethylene propylene diene monomer and polymer cement coatings. The radon diffusion coefficients for waterproofings widely used for protecting houses, i.e. flexible polyvinyl chloride, high-, low-density polyethylene, polypropylene and bitumen membranes, vary in the range from 3 × 10(-12) to 3 × 10(-11) m(2) s(-1). Tests were performed which confirmed that the radon diffusion coefficient is also an effective tool for verifying the air-tightness of joints. PMID:21450700

Jiránek, M; Kotrbatá, M

2011-05-01

36

Chemical Composition and Fatty Acid Content of Some Spices and Herbs under Saudi Arabia Conditions  

PubMed Central

Some Saudi herbs and spices were analyzed. The results indicated that mustard, black cumin, and cress seeds contain high amount of fat 38.45%, 31.95% and 23.19%, respectively, as compared to clove (16.63%), black pepper (5.34%) and fenugreek (4.51%) seeds. Cress, mustard, black cumin and black pepper contain higher protein contents ranging from 26.61 to 25.45%, as compared to fenugreek (12.91%) and clove (6.9%). Crude fiber and ash content ranged from 6.36 to 23.6% and from 3.57 to 7.1%, respectively. All seeds contain high levels of potassium (ranging from 383 to 823?mg/100g), followed by calcium (ranging from 75 to 270?mg/100g), Magnesium (ranged from 42 to 102?mg/100g) and iron (ranged from 20.5 to 65?mg/100g). However, zinc, manganese and copper were found at low levels. The major fatty acids in cress and mustard were linolenic acid (48.43%) and erucic acid (29.81%), respectively. The lenoleic acid was the major fatty acid in black cumin, fenugreek, black pepper and clove oils being 68.07%, 34.85%, 33.03% and 44.73%, respectively. Total unsaturated fatty acids were 83.24, 95.62, 86.46, 92.99, 81.34 and 87.82% for cress, mustard, black cumin, fenugreek, black pepper and clove, respectively. The differences in the results obtained are due to environmental factors, production areas, cultivars used to produce seeds and also due to the different methods used to prepare these local spices. PMID:23319888

Al-Jasass, Fahad Mohammed; Al-Jasser, Mohammed Saud

2012-01-01

37

Fatigue Crack Measurement in Composite Materials by Ultrasonic Methods  

NASA Technical Reports Server (NTRS)

The nondestructive detection of intra-ply microcracking in unlined pressure vessels fabricated from composite materials is critical to ensuring mission success. Microcracking in composite structures due to combined fatigue and cryogenic thermal loading can be very troublesome to detect in-service and when it begins to link through the thickness can cause leakage and failure of the structure. These leaks may lead to loss of pressure/propellant, increased risk of explosion and possible cryo-pumping. The work presented herein develops a method and an instrument to locate and measure intraply fatigue cracking through the thickness of laminated composite material by means of correlation with ultrasonic resonance. Resonant ultrasound spectroscopy provides measurements which are, sensitive to both the microscopic and macroscopic properties of an object. Elastic moduli, acoustic attenuation, and geometry can all be probed. The approach is based on the premise of half-wavelength resonance. The method injects a broadband ultrasonic wave into the test structure using a swept frequency technique. This method provides dramatically increased energy input into the test article, as compared to conventional spike pulsed ultrasonics. This relative energy increase improves the ability to measure finer details in the materials character, such as micro-cracking and porosity. As the micro-crack density increases, more interactions occur with the higher frequency (small wavelength) components of the signal train causing the spectrum to shift toward lower frequencies. Preliminary experiments have verified a measurable effect on the resonance spectrum of the ultrasonic data to detect microcracking. Methods involving self organizing neural networks and other clustering algorithms show that the resonance ultrasound signatures from composites vary with the degree of microcracking and can be separated and identified.

Walker, James L.; Russell, Samuel S.; Suits, Michael W.; Workman, Gary L.; Watson, Jason M.; Thom, Robert (Technical Monitor)

2002-01-01

38

Iron–iron oxide composite thin films prepared by chemical vapor deposition from iron pentacarbonyl  

Microsoft Academic Search

Iron–iron oxide (Fe–Fe3O4) composite thin films were prepared by an atmospheric-pressure chemical vapor deposition method. Iron pentacarbonyl and carbon dioxide gas were used as source materials. The effect of carbon dioxide mole fraction on the structure of the film is discussed. For both Fe–Fe3O4 and Fe–?-Fe2O3 films, the magnetic properties were obtained from the hysteresis curve of in-plane magnetization. The

Toshiro Maruyama; Yoshitaka Shinyashiki

1998-01-01

39

Recycling By Solvolysis Thermosetting Composite Materials Of Sustainable Surface Transport  

SciTech Connect

A solvolysis process is studied to degrade an unsaturated polyester resin based on DCPD (dicyclopentadiene) and crosslinked with styrene, as the matrix of a composite material reinforced with long glass fibers. The study presented here investigates in particular the hydrolysis in conditions below the critical point of water (T<374 deg. C and P<221bar) in a batch reactor. Process window and parameter influences were studied by a Design of Experiments (DOE) approach (1). A tar-like substance issued from thermal degradations is formed in greater or lesser quantities depending on the operating conditions, and coats the fibers. The appearance of the composite samples and the degree of conversion for the degradation at 250 deg. C lead us to make a parallel with osmosis phenomena to explain the initiation mechanism of the degradation.

Oliveux, Geraldine; Le Gal La Salle, Eric [Laboratoire de Thermocinetique de Nantes (LTN), UMR CNRS 6607, Ecole Polytechnique de l'Universite de Nantes, Rue Christian Pauc, 44303 Nantes (France); Bailleul, Jean-Luc [Laboratoire Energetique, Mecanique et Materiaux(LE2M) de l'Institut Catholique des Arts et Metiers de Nantes, 35 avenue du champ de Manoeuvres, 44470 Carquefou (France)

2011-01-17

40

Recycling By Solvolysis Thermosetting Composite Materials Of Sustainable Surface Transport  

NASA Astrophysics Data System (ADS)

A solvolysis process is studied to degrade an unsaturated polyester resin based on DCPD (dicyclopentadiene) and crosslinked with styrene, as the matrix of a composite material reinforced with long glass fibers. The study presented here investigates in particular the hydrolysis in conditions below the critical point of water (T<374° C and P<221bar) in a batch reactor. Process window and parameter influences were studied by a Design of Experiments (DOE) approach (1). A tar-like substance issued from thermal degradations is formed in greater or lesser quantities depending on the operating conditions, and coats the fibers. The appearance of the composite samples and the degree of conversion for the degradation at 250° C lead us to make a parallel with osmosis phenomena to explain the initiation mechanism of the degradation.

Oliveux, Géraldine; Le Gal La Salle, Eric; Bailleul, Jean-Luc

2011-01-01

41

[The modification of the polymerization of composite materials by eugenol-containing temporary fillings].  

PubMed

The objective of this study was to evaluate the influence of eugenol-containing temporary fillings on the polymerisation of composite materials. Cavities of 2 mm in diameter and 2 mm in depth were prepared in enamel as well as in dentine. Immediately after preparation the cavities of the control group were filled with a light curing composite, a chemical curing composite, or a light and chemical curing composite. The cavities of the experimental group were filled with Nobetec (temporary filling material containing zinc-oxide-eugenol). After six weeks, the Nobetec fillings were removed by means of an excavator, the cavities were cleaned with water and filled with one of the above six composites. The specimens were embedded in Epofix and afterwards cut through the center of the filling. The cut surfaces were polished to 3 microns and afterwards (> 4 days) the hardness was measured with a Knoop hardness testing machine at different distances from the cavity wall. The results of the control group and of the experimental group were compared statistically. The polymerisation of five of the six materials was not inhibited by a temporary filling material containing zinc-oxide-eugenol. The difference in hardness for Brilliant Lux (light curing) was fer-highly significant (p < 0.001) between 0 micron and 100 microns from the cavity margin, if the cavity was first filled with a temporary filling material, containing zinc-oxide-eugenol. The results show that there exist certain composite filling materials that are inhibited in their polymerisation by the tested eugenol containing temporary filling material. PMID:1475669

Hotz, P; Schlatter, D; Lussi, A

1992-01-01

42

Manufacture of ceramic composites by forced chemical vapor infiltration techniques  

SciTech Connect

Forced chemical vapor infiltration (FCVI) methods have been developed to fabricate ceramic composites. The FCVI techniques allow the rapid densification of fibrous preforms with ceramic matrices. Computer-based modeling was used to develop a multi-step forced chemical vapor infiltration process. In particular, a finite-volume computer model, GTCVI, developed specifically for the FCVI process was used to determine optimal processing schemes. The results indicate that in the first step, processing conditions should be tailored to uniformly infiltrate the fine pores within fiber bundles. Once bundles are filled, conditions should be changed to compensate for new transport conditions and surface-to-volume effects associated with the coarse porosity between fiber bundles and layers of fabrics. The model-derived conditions allow processing times for a 1.3 cm thick preform to be decreased from 24 hours to 11 hours while maintaining an average final density greater than 85%.

Matlin, W.M.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States); Stinton, D.P.; Besmann, T.M. [Oak Ridge National Lab., TN (United States)

1995-12-31

43

HPTLC determination of chemical composition variability in raw materials used in botanicals.  

PubMed

Besides the chemotaxonomic value, nowadays determination of biodiversity and chemical variability has a commercial impact. The exact identity of raw material and constituents of botanical products, such as food supplements or herbal remedies, is a very important argument, being the real prerequisite for quality control and traceability, followed by the determination of active components. However, the analytical approach must consider the natural great variability in secondary metabolites and product form, such as in extracts. Against the reductive approach, on the basis of single chemical standards, so far dominant in Pharmacopoeias monographs, we report applications and utility of the high-performance thin-layer chromatography fingerprint in determination of species of the same genus, of populations of the same species and of different drugs of the same plant. PMID:24219430

Toniolo, Chiara; Nicoletti, Marcello; Maggi, Filippo; Venditti, Alessandro

2014-01-01

44

Compositional gaps in igneous rock suites controlled by magma system heat and water content  

NASA Astrophysics Data System (ADS)

The differentiation of basaltic magmas to form more silica-rich magma is a fundamental process in crustal magmatism. However, suites of volcanic rocks erupted from individual volcanic centres rarely exhibit a compositional continuum between basalt and rhyolite. Instead, some rock suites exhibit marked compositional gaps. The origin of such gaps has been attributed to partial melting of the crust, the immiscibility of different magma types, crystallization of specific mineral phases and processes occurring within magma chambers. Here we couple high pressure and temperature experiments on mantle-derived basalt from St Vincent Volcano, Lesser Antilles, with variable water contents, to thermal models of magma differentiation. We show that the compositional distribution of the derivative magma varies as a function of water and heat content of the magmatic system, which is, in turn, related to the flux and duration of magma input. Systems that have relatively low heat content are characterized by compositional gaps, whose extent varies systemically with the water in the parent basalt. Irrespective of water content, compositional gaps diminish with time. Our approach can be used to retrieve information from volcanic rocks on their magmatic heat and water content in the parent basalt and hence explore these parameters as functions of tectonic settings and age.

Melekhova, Elena; Annen, Catherine; Blundy, Jon

2013-05-01

45

Microstructure and properties of multiphase and functionally graded materials prepared by chemical vapor deposition  

SciTech Connect

The synthesis of multiphase and functionally graded materials by chemical vapor deposition is discussed from a perspective of controlling their composition and microstructure at a nano-scale level, and ultimately, tailoring their material properties. Prior research is briefly reviewed to address the current state of this novel material concept. Recent experimental results relating to controlling the selected properties of two multiphase systems, TiN + MoS{sub 2} and NiAl + Al{sub 2}O{sub 3}, are described to illustrate this concept`s potential merits and challenges for use in realistic applications.

Lee, W.Y.

1996-05-01

46

Influence of the methods of preparation, chemical and phase composition on the content of divalent chromium in chromium oxide catalysts  

Microsoft Academic Search

1.The content of divalent chromium in aluminochromium catalysts depends on the total content of chromium, the phase composition of aluminum hydroxide, and the nature of the chromium-containing compound taken for the preparation of the catalysts. At chromium contentrations of 6–7% the content of Cr2+ passes through a maximum. The amount of Cr2+ increases from catalysts based on ?-Al2O3 to catalysts

K. I. Slovetskaya; É. G. Aleshin; A. M. Rubinshtein

1973-01-01

47

Impact damage detection of composite materials by fiber Bragg gratings  

NASA Astrophysics Data System (ADS)

Usage of fiber-optic Bragg gratings (FBG) for strain measurement is well-known technique in structural health monitoring (SHM). However, this technique based on shift of spectral peak, suffers from different spurious signals, particularly caused by thermal effect. We present here a method for impact damage detection of composite materials based on FBG without thermal disturbance. This method is based on the broadening of the spectral peak in dependence on the FBG separation from the impact damage. We used a sensing configuration where an Optical Spectrum Analyzer was interrogated with an array of 10 FBGs with central wavelength between 812 and 817nm that were bonded on a CFRP composite plate with 8 plies. We performed two groups of impact experiments: by impact energy of about 10J and 20J. We found there was no any significant shift of the spectral peak after the impact. Contrary, we confirmed in the last experiments the spectral peak broadening caused by impact load. The spectrum broadening primarily depends on the strain gradient generated into the FBGs, i.e. into the damaged area. We made a correlation between the peak width and FBG-impact damage separation. There are three characteristic regions; near to impact, abrupt region and almost even region.

Djinovic, Zoran; Scheerer, Michael; Tomic, Milos

2011-06-01

48

HDPE-HA composites synthetized by in situ polymerization with different filler content  

NASA Astrophysics Data System (ADS)

In Situ ethylene polymerization was used to synthesize high density polyethylene - hydroxyapatite (HDPE-HA) composites, employing Cp2ZrCl2/MAO as catalytic system. A good dispersion of HA into the HDPE matrix was obtained when the following synthesis conditions were combined: high stirring velocities (2000 rpm), low quantities of solvent (100 mL), and 10 °C. Under these conditions different filler content was used to synthetized HDPE-HA composites. An interaction between HA and HDPE was obtained by FTIR. On the other hand, thermal analysis indicated that no significant differences were observed between HDPE and the composites.

Hermán, V.; Karam, A.; Albano, C.; Romero, K.; González, G.

2012-07-01

49

Major element chemical compositions of chondrules in unequilibrated chondrites  

NASA Technical Reports Server (NTRS)

The chemical compositions (except for metals and sulfides in chondrules) of more than 500 chondrules from unequilibrated E, H, L, LL, and C chondrites were measured using a broad beam of an electron-probe microanalyzer. The compositions of chondrules can be represented by various mixtures of normative compositions of olivine, low-Ca pyroxene, plagioclase, and high-Ca pyroxene with minor amounts of spinel, feldspathoid, SiO2-minerals, etc., indicating that the chondrule precursor materials consisted of aggregates of these minerals. The Al, Na, and K contents of most chondrules reflect the compositions of the ternary feldspar (An-Ab-Kf) of the chondrule precursor materials, and chemical types of chondrules (KF, SP, IP, and CP) are defined on the basis of the atomic proportion of Al, Na, and K.

Ikeda, Y.

1984-01-01

50

Recycling By Solvolysis Thermosetting Composite Materials Of Sustainable Surface Transport  

Microsoft Academic Search

A solvolysis process is studied to degrade an unsaturated polyester resin based on DCPD (dicyclopentadiene) and crosslinked with styrene, as the matrix of a composite material reinforced with long glass fibers. The study presented here investigates in particular the hydrolysis in conditions below the critical point of water (T<374° C and P<221bar) in a batch reactor. Process window and parameter

Géraldine Oliveux; Eric Le Gal La Salle; Jean-Luc Bailleul

2011-01-01

51

Regulating continent growth and composition by chemical weathering  

PubMed Central

Continents ride high above the ocean floor because they are underlain by thick, low-density, Si-rich, and Mg-poor crust. However, the parental magmas of continents were basaltic, which means they must have lost Mg relative to Si during their maturation into continents. Igneous differentiation followed by lower crustal delamination and chemical weathering followed by subduction recycling are possible solutions, but the relative magnitudes of each process have never been quantitatively constrained because of the lack of appropriate data. Here, we show that the relative contributions of these processes can be obtained by simultaneous examination of Mg and Li (an analog for Mg) on the regional and global scales in arcs, delaminated lower crust, and river waters. At least 20% of Mg is lost from continents by weathering, which translates into >20% of continental mass lost by weathering (40% by delamination). Chemical weathering leaves behind a more Si-rich and Mg-poor crust, which is less dense and hence decreases the probability of crustal recycling by subduction. Net continental growth is thus modulated by chemical weathering and likely influenced by secular changes in weathering mechanisms. PMID:18362343

Lee, Cin-Ty Aeolus; Morton, Douglas M.; Little, Mark G.; Kistler, Ronald; Horodyskyj, Ulyana N.; Leeman, William P.; Agranier, Arnaud

2008-01-01

52

Nondestructive testing of composite materials by holographic interferometry  

Microsoft Academic Search

Techniques for the nondestructive testing of composites by holographic interferometry are discussed, and results from tests analyzing carbon\\/epoxy composites for two types of defects, resulting from the impact of steel rods and the introduction of mylar inhomogeneities, are presented. Holographic techniques for the interferometric real-time observation of the superposition of the object and the holographic image, and for the recording

J. Ebbeni; M.-A. de Smet

1987-01-01

53

Improved fiber-reinforced SiC composites fabricated by chemical vapor infiltration  

SciTech Connect

Fabrication of fiber-reinforced composites by a patented chemical vapor infiltration process has continued. Modifications to the process used for infiltration of unidirectional preforms resulted in more uniform matrix deposition throughout the preform and improved mechanical properties of the composites. Infiltration of improved cloth preforms containing more uniform porosity resulted in composites with fewer and smaller voids.

Stinton, D.P.; Caputo, A.J.; Lowden, R.A.; Besmann, T.M.

1986-01-01

54

Fabrication of fiber-reinforced composites by chemical vapor infiltration  

SciTech Connect

A two-step forced chemical vapor infiltration process was developed that reduced infiltration times for 4.45 cm dia. by 1.27 cm thick Nicalon{sup +} fiber preforms by two thirds while maintaining final densities near 90 %. In the first stage of the process, micro-voids within fiber bundles in the cloth were uniformly infiltrated throughout the preform. In the second stage, the deposition rate was increased to more rapidly fill the macro-voids between bundles within the cloth and between layers of cloth. By varying the thermal gradient across the preform uniform infiltration rates were maintained and high final densities achieved.

Matlin, W.M. [Univ. of Tennessee, Knoxville, TN (United States); Stinton, D.P.; Besmann, T.M. [Oak Ridge National Lab., TN (United States)

1995-08-01

55

Optimization model coupling both chemical compositions and high-temperature characteristics of sintering materials for sintering burden  

NASA Astrophysics Data System (ADS)

We developed a mathematical optimization model coupling chemical compositions and high-temperature characteristics of sintering materials, targeting the best quality and lowest cost. The simplex algorithm was adopted to solve this model. Four kinds of imported iron ores, two kinds of Chinese iron ore concentrates, and two kinds of fluxes were selected to verify both the model and the algorithm. The results confirmed the possibility of considering both chemical compositions and high-temperature characteristics of iron ores in the optimization model. This model provides a technical roadmap to obtain a precise mathematical correlation between the lowest cost and the grade of iron in sinters based on the condition of given raw materials, which can provide a reference to adjust the grade of iron in the sintering process for enterprise.

Li, Ke-jiang; Zhang, Jian-liang; Liu, Zheng-jian; Su, Bu-xin; Kong, Ling-tan; Yang, Tian-jun

2014-03-01

56

Treatment of chemical warfare agents by zero-valent iron nanoparticles and ferrate(VI)\\/(III) composite  

Microsoft Academic Search

Nanoscale zero-valent iron (nZVI) particles and a composite containing a mixture of ferrate(VI) and ferrate(III) were prepared by thermal procedures. The phase compositions, valence states of iron, and particle sizes of iron-bearing compounds were determined by combination of X-ray powder diffraction, Mössbauer spectroscopy and scanning electron microscopy. The applicability of these environmentally friendly iron based materials in treatment of chemical

Radek Zboril; Marek Andrle; Frantisek Oplustil; Libor Machala; Jiri Tucek; Jan Filip; Zdenek Marusak; Virender K. Sharma

57

Chemical composition and mineralogy of borate from Rio Grande deposit, Uyuni (Bolivia) as raw materials for industrial applications  

NASA Astrophysics Data System (ADS)

Bolivia has large tailings as a result of the historic and present-day Sn mining activity developed extensively in that country. Tailings produced in these mining activities have an appropriate composition to reprocess them and make silicate glass and glass-ceramics, obtaining the valorization of wastes and reducing the visual and chemical impact. Reprocessing the wastes to make glass and glass-ceramics prevents the leaching of heavy metals from those wastes because they are retained in the structure of the glass. Furthermore, an option to increase the economic value of these glasses is the introduction of boron and other additives to produce borosilicate glass. In this study a characterization of the Rio Grande borate deposit for its use in the manufacture of borosilicate glass is presented. Mineralogy was determined by X-ray diffraction (XRD), and Fourier transforms infrared spectroscopy (FTIR); textures were observed by scanning electron microscopy (SEM) and chemical composition was determined by inductively coupled plasma mass spectrometry (ICP-MS). The Rio Grande borate deposit is located in an area of about 50 km2 close to the south of the Salar of Uyuni, in the Río Grande de Lípez Delta. Borates occur in the contact between fluvio-deltaic and lacustrine sediments from water raising the surface by capillarity. The borates crop out in an extent area but towards the west they are covered by fluvio-deltaic sediments, which can be up to 2 m thick. These borates occur as lenses 50-100 m in diameter and layers up to 1 m thick. They usually form brittle nodules with a cotton-ball texture. Chemical composition of the Rio Grande borates is CaO, 11.82-13.83 wt%; Na2O, 13.50-19.35 wt%; K2O, 0.05- 1.04 wt%; MgO, 0.42-1.46 wt%; B2O3, 36.21-42.60 wt%; SiO2, up to 0.53 wt% and SO2, up to 0.60 wt%. Trace elements are low: Sr content is between 151-786 ppm, Al 12-676 ppm, Mn between 1-17 ppm, As 2-10 ppm and Fe between 9-376 ppm. The most abundant borate mineral in this deposit is ulexite (NaCaB5.5H20), halite can reach up to 17 wt% and gypsum up to 1.2 wt.%. Calcite occurs in minor contents. Ulexite exhibits a fibrous morphology with fibers oriented parallel each other. Purity of borates from the Rio Grande deposits makes them suitable for the most restrictive applications. Chemistry of these borates is in accordance with the necessary composition for obtaining borosilicate glasses. Acknowledgements: This work was partly financed by the project AECID: A3/042750/11, and the SGR 2009SGR-00444.

Guillen Vargas, Julio; Arancibia, Jony Roger Hans; Alfonso, Pura; Garcia-Valles, Maite; Parcerisa, David; Martinez, Salvador

2014-05-01

58

Comparison of Chemical Composition of Complex Disinfection Byproduct (DBP) Mixtures Produced by Different Treatment Methods - slides  

EPA Science Inventory

Analyses of the chemical composition of complex DBP mixtures, produced by different drinking water treatment processes, are essential to generate toxicity data required for assessing their risks to humans. For mixture risk assessments, whole mixture toxicology studies generally a...

59

Comparison of Chemical Composition of Complex Disinfection Byproduct (DBP) Mixtures Produced by Different Treatment Methods  

EPA Science Inventory

Analyses of the chemical composition of complex DBP mixtures, produced by different drinking water treatment processes, are essential to generate toxicity data required for assessing their risks to humans. For mixture risk assessments, whole mixture toxicology studies generally a...

60

Effect of chemical composition on corneal cellular response to photopolymerized materials comprising 2-hydroxyethyl methacrylate and acrylic acid.  

PubMed

Characterization of corneal cellular response to hydrogel materials is an important issue in ophthalmic applications. In this study, we aimed to investigate the relationship between the feed composition of 2-hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc) and material compatibility towards corneal stromal and endothelial cells. The monomer solutions of HEMA and AAc were mixed at varying volume ratios of 92:0, 87:5, 82:10, 77:15, and 72:20, and were subjected to UV irradiation. Results of electrokinetic measurements showed that an increase in absolute zeta potential of photopolymerized membranes is observed with increasing the volume ratios of AAc/HEMA. Following 4 days of incubation with various hydrogels, the primary rabbit corneal stromal and endothelial cell cultures were examined for viability, proliferation, and pro-inflammatory gene expression. The samples prepared from the solution mixture containing 0-10 vol.% AAc displayed good cytocompatibility. However, with increasing volume ratio of AAc and HEMA from 15:77 to 20:72, the decreased viability, inhibited proliferation, and stimulated inflammation were noted in both cell types, probably due to the stronger charge-charge interactions. On the other hand, the ionic pump function of corneal endothelial cells exposed to photopolymerized membranes was examined by analyzing the Na(+),K(+)-ATPase alpha 1 subunit (ATP1A1) expression level. The presence of material samples having higher anionic charge density (i.e., zeta potential of -38 to -56 mV) may lead to abnormal transmembrane transport. It is concluded that the chemical composition of HEMA/AAc has an important influence on the corneal stromal and endothelial cell responses to polymeric biomaterials. PMID:23910267

Lai, Jui-Yang

2013-10-01

61

Water defluoridation by aluminium oxide-manganese oxide composite material.  

PubMed

In this study, aluminium oxide-manganese oxide (AOMO) composite material was synthesized, characterized, and tested for fluoride removal in batch experiments. AOMO was prepared from manganese(II) chloride and aluminium hydroxide. The surface area of AOMO was found to be 30.7m2/g and its specific density was determined as 2.78 g/cm3. Detailed investigation of the adsorbent by inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry, and ion chromatography (for sulphate only) showed that it is composed of Al, Mn, SO4, and Na as major components and Fe, Si, Ca, and Mg as minor components. Thermogravimetric analysis was used to study the thermal behaviour of AOMO. X-ray diffraction analysis showed that the adsorbent is poorly crystalline. The point of zero charge was determined as 9.54. Batch experiments (by varying the proportion of MnO, adsorbent dose, contact time, initial F concentration, and raw water pH) showed that fluoride removal efficiency ofAOMO varied significantly with percentage of MnO with an optimum value of about I11% of manganese oxide in the adsorbent. The optimum dose of the adsorbent was 4 g/L which corresponds to the equilibrium adsorption capacity of 4.8 mg F-/g. Both the removal efficiency and adsorption capacity showed an increasing trend with an increase in initial fluoride concentration of the water. The pH for optimum fluoride removal was found to be in the range between 5 and 7. The adsorption data were analysed using the Freundlich, Langmuir, and Dubinirn-Radushkevich models. The minimum adsorption capacity obtained from the non-linear Freundlich isotherm model was 4.94 mg F-/g and the maximum capacity from the Langmuir isotherm method was 19.2mg F-/g. The experimental data of fluoride adsorption on AOMO fitted well to the Freundlich isotherm model. Kinetic studies showed that the adsorption is well described by a non-linear pseudo-second-order reaction model with an average rate constant of 3.1 x 10(-2) g/min mg. It is concluded that AOMO is a highly promising adsorbent for the removal of excess fluoride from drinking water. PMID:24956783

Alemu, Sheta; Mulugeta, Eyobel; Zewge, Feleke; Chandravanshi, Bhagwan Singh

2014-08-01

62

Light energy transmission through composite influenced by material shades.  

PubMed

This study investigated the influence of different composite resin shades on light energy transmission through the composite, hardness and cross-link density (CLD). The composite Filtek Z250 was used in shades A1, A2, A3, A3.5 and A4. A quartz tungsten halogen light curing unit was used at an irradiance of 900 mW/cm(2). Thirty specimens were made for each shade. Light energy transmission that passed through the composite was calculated (n=10). Differences in Knoop hardness between the top and bottom (DKH) of the same specimen were calculated (n=10). The Knoop hardness value for each surface was recorded as the average of three indentations (KHN(1)). Thereafter, the specimens were soaked in absolute ethanol for 24hr at room temperature, and hardness was again determined (KHN(2)). The CLD was estimated by the softening effect produced by ethanol, i.e., by decrease in hardness. The percentage of decrease in KHN(2) compared with KHN(1) (PD) in the same specimen was then calculated for both surfaces (n=10). The data were submitted to an ANOVA in different tests (Light energy transmission, Knoop hardness and CLD). The irradiance of light that passed through composite shade A1 (408 mW/cm(2)) was statistically greater than that through shade A2 (376 mW/cm(2)), and was greater through A2 than A3 (359 mW/cm(2)) and through A3 than A3.5 (327 mW/cm(2)); A3.5 showed no statistical difference when compared to A4 (324 mW/cm(2)). The DKH of A4 (20.56%) was not statistically higher than that of A3.5 (20.14%), which was greater than that of A3 (14.08%), A2 (11.65%) and A1 (9.06%). There was no statistical difference in CLD. Darker shades had a significant influence on light energy transmission through dental resin composite and its hardness. However, CLD was not affected by darker dental composite shades. PMID:20179393

Guiraldo, Ricardo Danil; Consani, Simonides; Consani, Rafael Leonardo Xediek; Berger, Sandrine Bittencourt; Mendes, Wilson Batista; Sinhoreti, Mario Alexandre Coelho

2009-01-01

63

Composite Materials Handbook  

NSDL National Science Digital Library

From the US Army Research Laboratory, Materials Sciences Corporation, and University of Delaware Center for Composite Materials, the Composite Materials Handbook provides the "information and guidance necessary to design and fabricate end items from composite materials." Along with current information on the material properties of these composite materials, the handbook also includes data development and usage guidelines. The information has been divided into three areas: polymer, metal, and ceramic matrix composites. The Polymer Matrix Composites Handbook (three volumes including Guidelines for Characterization of Structural Materials; Material Properties; and Materials Usage, Design, and Analysis) and the Metal Matrix Composites Handbook (one volume, .pdf) are available here. The Ceramic Matrix Composites Handbook has yet to be completed. Users may also download Quick Composites Data in spreadsheet format.

64

Effect of chemical composition on corneal tissue response to photopolymerized materials comprising 2-hydroxyethyl methacrylate and acrylic acid.  

PubMed

The purpose of this work was to investigate the relationship between the feed composition of 2-hydroxyethyl methacrylate (HEMA)/acrylic acid (AAc) and hydrogel material compatibility towards ocular anterior segment tissues, particularly the corneal endothelium. The monomer solutions of HEMA and AAc were mixed at varying volume ratios of 92:0, 87:5, 82:10, 77:15, and 72:20, and were subjected to UV irradiation. Then, the 7-mm-diameter membrane implants made from photopolymerized materials were placed into the ocular anterior chamber for 4days and assessed by biomicroscopic examinations, corneal thickness measurements, and quantitative real-time reverse transcription polymerase chain reaction analyses. The poly(HEMA-co-AAc) implants prepared from the solution mixture containing 0-10vol.% AAc displayed good biocompatibility. However, with increasing volume ratio of AAc and HEMA from 15:77 to 20:72, the enhanced inflammatory response, decreased endothelial cell density, and increased ocular score and corneal thickness were observed, probably due to the influence of surface charge of copolymer membranes. On the other hand, the ionic pump function of corneal endothelium exposed to photopolymerized membranes was examined by analyzing the Na(+),K(+)-ATPase alpha 1 subunit (ATP1A1) expression level. The presence of the implants having higher amount of AAc incorporated in the copolymers (i.e., 15.1 to 24.7?mol) and zeta potential (i.e., -38.6 to -56.5mV) may lead to abnormal transmembrane transport. It is concluded that the chemical composition of HEMA/AAc has an important influence on the corneal tissue responses to polymeric biomaterials. PMID:24268266

Lai, Jui-Yang

2014-01-01

65

Biosorption of heavy metal ions from aqueous solutions by short hemp fibers: Effect of chemical composition  

Microsoft Academic Search

Sorption potential of waste short hemp fibers for Pb2+, Cd2+ and Zn2+ ions from aqueous media was explored. In order to assess the influence of hemp fiber chemical composition on their heavy metals sorption potential, lignin and hemicelluloses were removed selectively by chemical modification. The degree of fiber swelling and water retention value were determined in order to evaluate the

Biljana Pejic; Marija Vukcevic; Mirjana Kostic; Petar Skundric

2009-01-01

66

Study on the chemical composition features of Longquan celadon excavated from the Chuzhou site of Huai'an City in Jiangsu Province by EDXRF  

NASA Astrophysics Data System (ADS)

A mass of Longquan celadon shards were excavated from the Chuzhou site of Huai'an City in Jiangsu Province, China. These celadon shards were fired during the period of the Late Yuan Dynasty to the Tianshun era of the Ming Dynasty, as identified by archaeologists at Nanjing Museum. In order to research the chemical composition features of this ancient celadon porcelain, energy dispersive X-ray fluorescence (EDXRF) for non-destructive analysis was used to determine the chemical composition of the porcelain body and glaze in these shards. The results indicate that Ti and Fe in the body of Longquan celadon are characteristic elements which can distinguish porcelain produced during the Late Yuan Dynasty from those produced in the Ming Dynasties. The results of the principal component analysis (PCA) show that different body and glaze raw materials were used for the production of porcelain in different periods and the raw materials of the body and glaze are also different for various vessel shapes. The chemical compositions in the porcelain body of civilian ware are slightly different. The imperial and civilian Longquan celadon porcelains produced during the Hongwu era to the Tianshun era of the Ming Dynasty are distinguishable by the MnO, Fe2O3, Rb2O and SrO content in their porcelain glaze.

Li, Li; Feng, Song-Lin; Feng, Xiang-Qian; Xu, Qing; Yan, Ling-Tong; Ma, Bo; Huo, Hua

2011-07-01

67

Composite structural materials  

NASA Technical Reports Server (NTRS)

Various topics relating to composite structural materials for use in aircraft structures are discussed. The mechanical properties of high performance carbon fibers, carbon fiber-epoxy interface bonds, composite fractures, residual stress in high modulus and high strength carbon fibers, fatigue in composite materials, and the mechanical properties of polymeric matrix composite laminates are among the topics discussed.

Loewy, R. G.; Wiberley, S. E.

1985-01-01

68

Modification of nanoparticle-organic composite electronic materials for improved chemical sensors.  

SciTech Connect

Molecular electronic based chemical vapor sensors were assembled using noble metal nanoparticles and short conjugated phenylene ethynylene (PE) based molecules. Sacrificial capping ligands on the nanoparticles were replaced by tighter binding PE ligands. The films were assembled between pairs of electrodes by iteratively exposing the substrates to solutions of the nanoparticles and PE crosslinking bridging ligands. Some of the conjugated bridging molecules contained an electron deficient phenol to provide a simple platform for developing sensor applications. The phenol is calculated to have a significant change in its HOMO/LUMO gap in the presence of specific analytes. Judicious combination of nanoparticle size and ligand structure provides a film in which the organic bridging ligands dramatically affect film conductance. Specifically, {pi}-conjugated ligands lower resistance more in films with smaller particles. Thus the sensing mechanism of these films is not based on the typical swelling mechanism but rather on the modulation of the molecular electronic structure of the conducting PE bridging ligands. Interdigitated Au electrodes built on quartz substrates were first silanized with tetrakis(dimethylamino)silane. The remaining amino functionalities were displaced with 1,8-octanedithiol (ODT) to give a thiolated surface capable of binding nanoparticles. The substrate was then incubated in a solution of dodecylamine-capped nanoparticles. The film thickness was increased via alternating exposure to solutions of bifunctional crosslinking molecules and nanoparticles (Figure 1). Nanoparticles and assembled films were characterized by TEM and AFM prior to electrical characterization. After verifying the selectivity of this new attachment chemistry, a novel robotic sample preparation was employed to build nanoparticle films of different thickness on prepared electrodes. By preparing the nanoparticle films using a robot, many problems with irregularities of the deposited films were eliminated. This sample preparation system was designed with the capability to measure the resistivity of the nanoparticle films after assembly of each layer. Using such a sample preparation system is vital for developing mass-produced sensors from nanoparticle films. The robotic system was used to deposit and measure the electrical properties of Pt and Au nanoparticles linked with different ligands such as ODT and meta-PE diisocyanide. Figure 2 is a plot showing the resistance vs. film layer for several combinations of nanoparticles and linker-ligands. The data shows that the resistance of the film drops and eventually saturates as additional nanoparticle layers are deposited. There is also an inversion in the resistance per layer that depends on the nanoparticle's type and the ligand used to crosslink the film. This data is significant because it shows how the selection of certain nanoparticle properties (such as size and material) and selection of an appropriate linking ligand can be used to tune the conductance of a film composed of nanoparticles. It is well known that smaller nanoparticles have a higher charging potential. This coupled with the inherent variability of organic molecules ensures that a film in which the organic molecules dominate conductivity can be achieved. In addition to the experiments above, nanoparticle films were assembled using cross-linkers that can be modified by an analyte. Figure 3 shows a typical I(V) curve for a Au nanoparticle film crosslinked with a phenylene ethynylene based electron deficient phenol. There is a clear reversible change in the resistance of the film when exposed first to acid and then base. The generation of a new response mechanism for nanoparticle films greatly increases the scope of organic/nanoparticle films for sensor applications. Their crosslinked nature increases their robustness and allows for use in both aqueous as well as organic solutions. In summary, we have developed a novel reproducible sample preparation system for the deposition of crosslinked nanoparticle films on a variety of sub

Howell, Stephen Wayne; Dirk, Shawn M.; Wheeler, David A.

2005-03-01

69

Random composites of nickel networks supported by porous alumina toward double negative materials.  

PubMed

Random composites with nickel networks hosted randomly in porous alumina are proposed to realize double negative materials. The random composite for DNMs (RC-DNMs) can be prepared by typical processing of material, which makes it possible to explore new DNMs and potential applications, and to feasibly tune their electromagnetic parameters by controlling their composition and microstructure. Hopefully, various new RC-DNMs with improved performance will be proposed in the future. PMID:22499287

Shi, Zhi-cheng; Fan, Run-hua; Zhang, Zi-dong; Qian, Lei; Gao, Meng; Zhang, Mo; Zheng, Li-tuo; Zhang, Xi-hua; Yin, Long-wei

2012-05-01

70

Thermodynamics for the preparation of SiC-C nano-composites by chemical vapour deposition  

Microsoft Academic Search

SiC-C nano-composites covering every possible combination of carbon and SiC were prepared by chemical vapour deposition. The specific compositions of the deposits were controlled by changing the Si\\/C molar ratio in the source gases at deposition temperatures (Tdep) of 1673 to 1873 K and total gas pressures (Ptot) of 6.7 to 40 k Pa using the SiCl4-C3H8-H2 system. The prediction,

Y. Wang; M. Sasaki; T. Goto; T. Hirai

1990-01-01

71

Chemical recycling of scrap composites  

NASA Technical Reports Server (NTRS)

There are no well-developed technologies for recycling composite materials other than grinding to produce fillers. New approaches are needed to reclaim these valuable resources. Chemical or tertiary recycling, conversion of polymers into low molecular weight hydrocarbons for reuse as chemicals or fuels, is emerging as the most practical means for obtaining value from waste plastics and composites. Adherent Technologies is exploring a low-temperature catalytic process for recycling plastics and composites. Laboratory results show that all types of plastics, thermosets as well as thermoplastics, can be converted in high yields to valuable hydrocarbon products. This novel catalytic process runs at 200 C, conversion times are rapid, the process is closed and, thus, nonpolluting, and no highly toxic gas or liquid products have been observed so no negative environmental impact will result from its implementation. Tests on reclamation of composite materials show that epoxy, imide, and engineering thermoplastic matrices can be converted to low molecular weight hydrocarbons leaving behind the reinforcing fibers for reuse as composite reinforcements in secondary, lower-performance applications. Chemical recycling is also a means to dispose of sensitive or classified organic materials without incineration and provides a means to eliminate or reduce mixed hazardous wastes containing organic materials.

Allred, Ronald E.; Salas, Richard M.

1994-01-01

72

Improved pinning properties in Y123 materials by chemical substitutions.  

SciTech Connect

We have investigated how T{sub c}, J{sub c} and B{sub irr} of compounds with double CuO{sub 2} planes depend on the physical properties and structural features of the blocking layer. By comparing J{sub c} and B{sub irr} for several families of HTSC we have concluded that the intrinsic flux pinning is controlled to a large extent by the conductivity of the blocking layer. The width of the intermediate region between the blocks of the double CuO{sub 2} planes is less significant. To modify the conductivity of the CuO chains and decrease the anisotropy of the YBa{sub 2}Cu{sub 3}O{sub y} compound, substitutions of transition elements for Cu and Sr for Ba were done resulting in enhanced pinning properties and increased T{sub c} of YBaSrCu{sub 3-x}Mo{sub x}O{sub y} from 81 K for x=0 to 86 K for x=0.05-0.1. The pinning characteristics of substituted material were significantly modified most likely by a formation of dimers of corner shared MoO{sub 6} octahedra. The same structural modification was used to improve the pinning properties of the YBa{sub 2}Cu{sub 3}O{sub y} compound.

Rogacki, K.; Dabrowski, B.; Chmaissem, O.; Jorgensen, J. D.; Materials Science Division; Illinois Inst. of Tech.; Science Univ. of Tokyo; Naval Research Lab.

2000-01-01

73

Characterization of Chemical Polishing Materials by means of Acoustic Spectroscopy  

Microsoft Academic Search

It is shown that acoustic spectroscopy can sense the presence of a small sub- population of large particles in a concentrated dispersion of much smaller particles. The detection limit can be as low as a single one micron particle per 100,000 particles of 100 nm size. This is equivalent to a large particle content of 1 wt. % relative to

Andrei S. Dukhin; Philip J. Goetz

74

Regulating continent growth and composition by chemical weathering  

E-print Network

Nicolas Copernic, 29280 Plouzane, France Edited by Norman H. Sleep, Stanford University, Stanford, CA Agranier*, ** *Department of Earth Science, MS-126, Rice University, 6100 Main Street, Houston, TX 77005; U.S. Geological Survey and Department of Earth Sciences, University of California, Riverside, CA 92521; §U

Lee, Cin-Ty Aeolus

75

Determination of isoflavone content in soy, red clover, and kudzu dietary supplement materials by liquid chromatography-particle beam/electron ionization mass spectrometry.  

PubMed

Increased consumption of dietary supplements brings about important requirements of analytical methods to allow accurate and precise measurements of the chemical composition of these botanical materials. Presented here is the isoflavone content in proposed National Institute of Standards and Technology standard reference materials (SRMs) determined by LC-particle beam/electron ionization MS. Botanical materials (soy, red clover, and kudzu) are characterized for the content of a suite of five isoflavones (puerarin, daidzein, genistein, formononetin, and biochanin A). These compounds are of interest due to correlations with certain health benefits. An RP chromatographic separation was first optimized using UV-Vis spectrophotometric detection. The LC output was then introduced to an electron ionization source using a particle beam interface on an Extrel Benchmark MS system. The separation was carried out using a commercial C18 column and a linear gradient using water and methanol (both containing 0.1% trifluoroacetic acid as mobile phases A and B, at a flow rate of 1.0 mL/min over 40 min. LOD values for the isoflavones were determined to be at the ng level. Quantitation was performed using an internal standard (IS) approach with 7-hydroxy-4-chromone as the IS compound. The levels of isoflavones in the botanical products were determined for the proposed SRMs. PMID:24282927

Burdette, Carolyn Q; Marcus, R Kenneth

2013-01-01

76

Air-gap sacrificial materials by initiated chemical vapor deposition  

E-print Network

P(neopentyl methacrylate-co-ethylene glycol dimethacrylate) copolymer, abbreviated as P(npMAco-EGDA), was selected as the potential air-gap sacrificial material among possible combination of twenty monomers and four ...

Lee, Long Hua

2007-01-01

77

Tough Composite Materials  

NASA Technical Reports Server (NTRS)

Papers and working group summaries are presented which address composite material behavior and performance improvement. Topic areas include composite fracture toughness and impact characterization, constituent properties and interrelationships, and matrix synthesis and characterization.

Vosteen, L. F. (compiler); Johnson, N. J. (compiler); Teichman, L. A. (compiler)

1984-01-01

78

Composite structural materials  

NASA Technical Reports Server (NTRS)

Technology utilization of fiber reinforced composite materials is discussed in the areas of physical properties, and life prediction. Programs related to the Composite Aircraft Program are described in detail.

Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

1979-01-01

79

Chemical composition of patikaraparpam.  

PubMed

Patikaraparpam, a Siddha formulation in prepared by trituration of potash alum with egg albumin followed by calcinatin. The three authentic laboratories made parpams as well as six commercial samples have been examined for their chemical composition. The analytical data that emerged from the analysis of the above samples showed that seven parpams contained only aluminium sulphate and they did respond to tests for potassium. An inspection of the crude drugs patikaram' available in the market established that potash alum and ammonia alum are indiscriminateldy taken for use, according to literature, only potash alum should be used in Indian system of medicine. Patikarapparapam is indicated in urinary inflammations and obstructions and is a reputed diuretic. Potassium salts are established diuretic. These studies show that the raw drugs sellers, the pharamaceutists or manufacturers of medicine and the physician as well should make sure that only potash alum is used in Indian medicine. PMID:22556804

Saraswathy, A; Rani, M G; Susan, T; Purushothaman, K K

1997-04-01

80

Chemical composition of Mars  

USGS Publications Warehouse

The composition of Mars has been calculated from the cosmochemical model of Ganapathy and Anders (1974) which assumes that planets and chondrites underwent the same 4 fractionation processes in the solar nebula. Because elements of similar volatility stay together in these processes, only 4 index elements (U, Fe, K and Tl or Ar36) are needed to calculate the abundances of all 83 elements in the planet. The values chosen are U = 28 ppb, K = 62 ppm (based on K U = 2200 from orbital ??-spectrometry and on thermal history calculations by Tokso??z and Hsui (1978) Fe = 26.72% (from geophysical data), and Tl = 0.14 ppb (from the Ar36 and Ar40 abundances measured by Viking). The mantle of Mars is an iron-rich [Mg/(Mg + Fe) = 0.77] garnet wehrlite (?? = 3.52-3.54 g/cm3), similar to McGetchin and Smyth's (1978) estimate but containing more Ca and Al. It is nearly identical to the bulk Moon composition of Morgan et al. (1978b). The core makes up 0.19 of the planet and contains 3.5% S-much less than estimated by other models. Volatiles have nearly Moon-like abundances, being depleted relative to the Earth by factors of 0.36 (K-group, Tcond = 600-1300 K) or 0.029 (Tl group, Tcond < 600 K). The water abundance corresponds to a 9 m layer, but could be higher by as much as a factor of 11. Comparison of model compositions for 5 differentiated planets (Earth, Venus, Mars, Moon, and eucrite parent body) suggests that volatile depletion correlates mainly with size rather than with radial distance from the Sun. However, the relatively high volatile content of shergottites and some chondrites shows that the correlation is not simple; other factors must also be involved. ?? 1979.

Morgan, J.W.; Anders, E.

1979-01-01

81

Composite ion exchange materials  

SciTech Connect

Composite ion exchange materials can be formed by sorbing ion exchange polymers on inert, high surface area substrates. In general, the flux of ions and molecules through these composites, as measured electrochemically, increases as the ratio of the surface area of the substrate increases relative to the volume of the ion exchanger. This suggests that fields and gradients established at the interface between the ion exchanger and substrate are important in determining the transport characteristics of the composites. Here, the authors will focus on composites formed with a cation exchange polymer, Nafion, and two different types of microbeads: polystyrene microspheres and polystyrene coated magnetic microbeads. For the polystyrene microbeads, scanning electron micrographs suggest the beads cluster in a self-similar manner, independent of the bead diameter. Flux of Ru(NH3)63+ through the composites was studied as a function of bead fraction, bead radii, and fixed surface area with mixed bead sizes. Flux was well modeled by surface diffusion along a fractal interface. Magnetic composites were formed with columns of magnetic microbeads normal to the electrode surface. Flux of Ru(NH3)63+ through these composites increased exponentially with bead fraction. For electrolyses, the difference in the molar magnetic susceptibility of the products and reactants, Dcm, tends to be non-zero. For seven redox reactions, the ratio of the flux through the magnetic composites to the flux through a Nafion film increases monotonically with {vert_bar}Dcm{vert_bar}, with enhancements as large as thirty-fold. For reversible species, the electrolysis potential through the magnetic composites is 35 mV positive of that for the Nafion films.

Amarasinghe, S.; Zook, L.; Leddy, J. [Univ. of Iowa, Iowa City, IA (United States)

1994-12-31

82

Composite structural materials  

NASA Technical Reports Server (NTRS)

A multifaceted program is described in which aeronautical, mechanical, and materials engineers interact to develop composite aircraft structures. Topics covered include: (1) the design of an advanced composite elevator and a proposed spar and rib assembly; (2) optimizing fiber orientation in the vicinity of heavily loaded joints; (3) failure mechanisms and delamination; (4) the construction of an ultralight sailplane; (5) computer-aided design; finite element analysis programs, preprocessor development, and array preprocessor for SPAR; (6) advanced analysis methods for composite structures; (7) ultrasonic nondestructive testing; (8) physical properties of epoxy resins and composites; (9) fatigue in composite materials, and (10) transverse thermal expansion of carbon/epoxy composites.

Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

1979-01-01

83

Physical, chemical and flavour quality of non-fat yogurt as affected by a ?-glucan hydrocolloidal composite during storage  

Microsoft Academic Search

In this study, a possible use of ?-glucan hydrocolloidal composite as a fat replacer in the manufacture of non-fat yogurts was investigated. The yogurts with added ?-glucan composite were compared with non-fat yogurt without addition of ?-glucan composite and the samples were analysed for physical, chemical and sensory attributes after 1, 7 or 15d of storage. Fat and protein contents

N. Sahan; K. Yasar; A. A. Hayaloglu

2008-01-01

84

One-step synthesis and chemical characterization of Pt-C nanowire composites by plasma sputtering  

E-print Network

to a thin film growth rate of ca. 4 nm min-1 . Electrodes loaded at 0.010 mg cm-2 Pt (Pt-CNW/CPL) with a PtOne-step synthesis and chemical characterization of Pt-C nanowire composites by plasma sputtering properties.[1-3] Nanomaterials have thus found numerous applications in chemistry, electronics, optics

Boyer, Edmond

85

Chemical Modification of Nanotubes for Composites  

NASA Technical Reports Server (NTRS)

In the production of mesoscopically-engineered materials based on single-walled carbon nanotubes (SWNTs), monitoring the stages of chemical modification will be an important step in the fabrication of usable composite materials. In our research program we developed tools for studying high-temperature composites with a long-term goal of having such instrumentation available for SWNT composite analyses.

Samulski, Edward T.

2003-01-01

86

Chemical imaging of biological materials by NanoSIMS  

SciTech Connect

The NanoSIMS 50 represents the state -of-the-art for in situ microanalysis for secondary ion mass spectrometry (SIMS), combining unprecedented spatial resolution (as good as 50 nm) with ultra-high sensitivity (MDL of 200 atoms). The NanoSIMS incorporates an array of detectors, enabling simultaneous collection of 5 elements or isotopes originating from the same sputtered volume of a sample. The primary ion beam (Cs{sup +} or O{sup -}) can be scanned across the sample to produce quantitative secondary ion images. This capability for multiple isotope imaging with high spatial resolution is unique to the NanoSIMS and provides a novel new approach to the study of the distribution of elements in biological materials. We have applied this technique extensively to mammalian cells and bacterial spores. Results from these studies and critical analytical issues such as sample preparation, instrument tuning, and data processing will be discussed.

Weber, P K; Smith, J B; Hutcheon, I D; Shmakov, A; Rybitskaya, I; Curran, H

2004-08-23

87

Composite structural materials  

NASA Technical Reports Server (NTRS)

The purpose of the RPI composites program is to develop advanced technology in the areas of physical properties, structural concepts and analysis, manufacturing, reliability and life prediction. Concommitant goals are to educate engineers to design and use composite materials as normal or conventional materials. A multifaceted program was instituted to achieve these objectives.

Ansell, G. S.; Wiberley, S. E.

1978-01-01

88

Origin and Bulk Chemical Composition of Mercury  

NASA Astrophysics Data System (ADS)

The planet Mercury is remarkable because its mean uncompressed density ~5.3 g/cc implies a metal content of ~67% by mass. This is more than twice the ~32% metal contents of each of Venus and Earth. This factor coupled with other marked chemical and isotopic differences between the four terrestrial planets points to the conclusion that each planet received the overwhelming majority of its mass from narrow compositionally-distinct annuli of material around the Sun (Drake & Righter 2002 Nature 416 43; Taylor & Scott 2001 in URL below). This situation finds an explanation within the Modern Laplacian theory of Solar system origin (Prentice 2001 Earth Moon & Planets 87 11 URL: www.lpi.usra.edu/meetings/mercury01). Here the planets condensed from a concentric family of circular gas rings shed by the proto-Solar cloud. The temperatures and mean orbit pressures of the gas rings scale with heliocentric distance r as T ~ 1/r0.9 and p ~ 1/r4.0 respectively. At the orbit of Mercury T = 1640 K p = 0.16 bar and the 3 primary equilibrium condensates are Fe-Ni-Cr-Co-V (67.0%) gehlenite (26.1%) and spinel (4.1%). A simple 2-zone structural model of Mercury based on this mix has mean density 5.43 g/cc and axial moment-of-inertia coefficent 0.325

Prentice, Andrew J.; Jontof-Hutter, Daniel

89

Composite material and method for production of improved composite material  

NASA Technical Reports Server (NTRS)

A laminated composite material with improved interlaminar strength and damage tolerance having short rods distributed evenly throughout the composite material perpendicular to the laminae. Each rod is shorter than the thickness of the finished laminate, but several times as long as the thickness of each lamina. The laminate is made by inserting short rods in layers of prepreg material, and then stacking and curing prepreg material with rods inserted therethrough.

Farley, Gary L. (Inventor)

1996-01-01

90

40 CFR Table Z-1 to Subpart Z of... - Default Chemical Composition of Phosphate Rock by Origin  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Default Chemical Composition of Phosphate Rock by Origin Z Table Z-1 to Subpart Z of Part 98 Protection...Subpart Z of Part 98—Default Chemical Composition of Phosphate Rock by Origin Origin Total carbon(percent by weight)...

2011-07-01

91

40 CFR Table Z-1 to Subpart Z of... - Default Chemical Composition of Phosphate Rock by Origin  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Default Chemical Composition of Phosphate Rock by Origin Z Table Z-1 to Subpart Z of Part 98 Protection...Subpart Z of Part 98—Default Chemical Composition of Phosphate Rock by Origin Origin Total carbon(percent by weight)...

2012-07-01

92

40 CFR Table Z-1 to Subpart Z of... - Default Chemical Composition of Phosphate Rock by Origin  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Default Chemical Composition of Phosphate Rock by Origin Z Table Z-1 to Subpart Z of Part 98 Protection...Subpart Z of Part 98—Default Chemical Composition of Phosphate Rock by Origin Origin Total carbon(percent by weight)...

2013-07-01

93

Processing of plastic waste and scrap tires into chemical raw materials, especially by pyrolysis  

Microsoft Academic Search

An account of the occurrence of pyrolyzable material and the state of development of pyrolysis processes in the USA and Japan is followed by a description of laboratory and pilot-scale experiments designed to exploit the raw material content of pyrolyzable substances rather than the heating value. Plastic waste and scrap tires can be pyrolyzed to give up to 40 percent

Walter Kaminsky

1976-01-01

94

Frying stability of high oleic sunflower oils as affected by composition of tocopherol isomers and linoleic acid content.  

PubMed

The influence of linoleic acid content and tocopherol isomeric composition on the frying performance of high oleic sunflower oil was evaluated during a 14-day restaurant style frying operation. At equal linoleic acid content, no significant difference was observed between high oleic sunflower oil containing only ?-tocopherol and the sample containing a mixture of ?-, ?-, and ?-isomers as measured by the amount of total polar components, oligomers, anisidine value, and free fatty acids. On the contrary, at similar tocopherol isomeric composition, high oleic sunflower oil containing lower amount of linoleic acid showed superior frying stability compared to the sample with a higher content of linoleic acid, suggesting that the frying performance of high oleic sunflower oil is dictated primarily by the level of linoleic acid, with the tocopherol isomeric composition of the oil having no significant influence. In all oil samples, the loss of ?-tocopherol was higher than the corresponding loss of ?-tocopherol. PMID:23870970

Aladedunye, Felix; Przybylski, Roman

2013-12-01

95

Chemical Composition of the Essential Oils of Achillea millefolium L. Isolated by Different Distillation Methods  

Microsoft Academic Search

The chemical composition of the essential oil from flowering tops of Achillea millefolium L. isolated by different distillation methods was studied. Samples were hydrodistilled with Clevenger-type (HD), simultaneous micro-distillation-extraction (SMDE), and microwave (MAHD) apparatus. The yields were 0.46% ± 0.03 for the HD and 0.48% ± 0.03 for the MAHD (v\\/w, volume\\/dry weight). The oils were analyzed by GC and

Carlo I. G. Tuberoso; Adam Kowalczyk

2009-01-01

96

Investigation of the chemical composition-antibacterial activity relationship of essential oils by chemometric methods.  

PubMed

The antibacterial effects of Thymus vulgaris (Lamiaceae), Lavandula angustifolia (Lamiaceae), and Calamintha nepeta (Lamiaceae) Savi subsp. nepeta var. subisodonda (Borb.) Hayek essential oils on five different bacteria were estimated. Laboratory control strain and clinical isolates from different pathogenic media were researched by broth microdilution method, with an emphasis on a chemical composition-antibacterial activity relationship. The main constituents of thyme oil were thymol (59.95%) and p-cymene (18.34%). Linalool acetate (38.23%) and ?-linalool (35.01%) were main compounds in lavender oil. C. nepeta essential oil was characterized by a high percentage of piperitone oxide (59.07%) and limonene (9.05%). Essential oils have been found to have antimicrobial activity against all tested microorganisms. Classification and comparison of essential oils on the basis of their chemical composition and antibacterial activity were made by utilization of appropriate chemometric methods. The chemical principal component analysis (PCA) and hierachical cluster analysis (HCA) separated essential oils into two groups and two sub-groups. Thyme essential oil forms separate chemical HCA group and exhibits highest antibacterial activity, similar to tetracycline. Essential oils of lavender and C. nepeta in the same chemical HCA group were classified in different groups, within antibacterial PCA and HCA analyses. Lavender oil exhibits higher antibacterial ability in comparison with C. nepeta essential oil, probably based on the concept of synergistic activity of essential oil components. PMID:22389175

Miladinovi?, Dragoljub L; Ili?, Budimir S; Mihajilov-Krstev, Tatjana M; Nikoli?, Nikola D; Miladinovi?, Ljiljana C; Cvetkovi?, Olga G

2012-05-01

97

Electrically conductive composite material  

DOEpatents

An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistant pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like.

Clough, Roger L. (Albuquerque, NM); Sylwester, Alan P. (Albuquerque, NM)

1989-01-01

98

Composite Structural Materials  

NASA Technical Reports Server (NTRS)

The development and application of filamentary composite materials, is considered. Such interest is based on the possibility of using relatively brittle materials with high modulus, high strength, but low density in composites with good durability and high tolerance to damage. Fiber reinforced composite materials of this kind offer substantially improved performance and potentially lower costs for aerospace hardware. Much progress has been made since the initial developments in the mid 1960's. There were only limited applied to the primary structure of operational vehicles, mainly as aircrafts.

Ansell, G. S.; Loewy, R. G.; Wiberly, S. E.

1984-01-01

99

Electrically conductive composite material  

DOEpatents

An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistent pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like. 2 figs.

Clough, R.L.; Sylwester, A.P.

1989-05-23

100

Electrically conductive composite material  

DOEpatents

An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistent pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like. 2 figs.

Clough, R.L.; Sylwester, A.P.

1988-06-20

101

Composite structural materials  

NASA Technical Reports Server (NTRS)

Overall emphasis is on basic long-term research in the following categories: constituent materials, composite materials, generic structural elements, processing science technology; and maintaining long-term structural integrity. Research in basic composition, characteristics, and processing science of composite materials and their constituents is balanced against the mechanics, conceptual design, fabrication, and testing of generic structural elements typical of aerospace vehicles so as to encourage the discovery of unusual solutions to present and future problems. Detailed descriptions of the progress achieved in the various component parts of this comprehensive program are presented.

Loewy, R.; Wiberley, S. E.

1986-01-01

102

Chemically produced tungsten-praseodymium oxide composite sintered by spark plasma sintering  

NASA Astrophysics Data System (ADS)

Pr2O3 doped W composite were synthesized by a novel wet chemical method and spark plasma sintering. The grain size, relative density and the Vicker hardness HV0.2 of Pr2O3/W samples were 4 ?m, 98.3% and 377.2, respectively. The tensile strength values of Pr2O3/W were higher than those of pure W. As the temperature rises from 25 °C to 800 °C, the conductivity of pure W and W-1 wt% Pr2O3 composites decreased with the same trend, was above 150 W/m K.

Ding, Xiao-Yu; Luo, Lai-Ma; Lu, Ze-Long; Luo, Guang-Nan; Zhu, Xiao-Yong; Cheng, Ji-Gui; Wu, Yu-Cheng

2014-11-01

103

Rapid determination of methanol content in paper materials by alkaline extraction, coupled with headspace analysis.  

PubMed

This study reports on a rapid method for the determination of methanol in paper-based materials by alkaline extraction, coupled with headspace analysis. Methanol partition equilibria between solid-liquid phases and vapor-liquid phases were conducted in two separate containers, from which an equation for calculating the total methanol content in the original paper sample was derived. It was found that the extraction equilibrium of methanol from solid sample could be achieved within 5min at room temperature using a high-speed disintegrator, and a subsequent neutralization step is an effective way to prevent methanol from being regenerated at high temperature during headspace equilibration. The results showed that the relative standard deviations for reproducibility tests were in the range of 1.86-6.03%, and the recoveries were in the range of 92.3-107%. The present method is simple and practical; it can be an efficient tool for quantifying the methanol content in paper-based materials and thus play an important role in the investigation of methanol migration behavior in food and beverage packaging. PMID:24861784

Zhang, Chun-Yun; Li, Ling-Ling; Chai, Xin-Sheng; Barnes, Donald G

2014-07-11

104

Specialized Content Material.  

ERIC Educational Resources Information Center

A computer-based set of instructional materials, designed to teach English second-language reading skills to university-level engineering students, is described and its development is outlined. The programmed units are designed to be used individually on the computer. The stages of software development included: selection of sentence units from…

Labbe, Raul; Varas, Amanda

105

Modelling of local modification of chemical composition generated by artificial beam injection in stratosphere  

NASA Astrophysics Data System (ADS)

The physical/chemical processes that are occurring in the middle atmosphere, are very complex and knowledge of them are obviously poor. At the same time the understanding of these processes is necessary, in particular, for an explanation of ozone dynamics and influencing on it of the different factors, for example, impurities of anthropogenous nature. In the present activity the capability of creation of noticeable local disturbances of concentration of ozone and other minor neutral components in stratosphere si theoretically modeled for artificial injection of high energy electron beams from a high-altitude balloon. With the help of numerical simulations (31 reactions) the quantitative assessments of expected effect for different altitudes (range of 35-45 km) and different values of eddy diffusion factor are obtained and presented. It is shown the considered means has a number of advantages in comparison with method of artificial action on stratosphere ozone by VHF generation of ionized area in atmosphere. At first, it is much more friend and precisely to conduct diagnostic of effect, which one arises due to "in -situ" onboard measurements from a balloon. Secondly, it is possible to inject any impurities (freons) to study directly in stratosphere their affect on ozone. The method, tendered here, requires considerably smaller material costs and can be realized already now. Based on presented modeling results it is important to note that in our method an integral disturbance in stratosphere (full quantity of created molecules of ozone, nitric oxides etc.) is rather insignificant, as the effect is localized near to injected electron beam. Therefore there is no hazard of deposition of unchecked injury to environment. At the same time realization of tendered experiment will allow essentially to deepen our representations about composite physical/chemical processes occurring in middle atmosphere (stratosphere).

Oraevsky, V.; Ruzhin, Y.; Borisov, N.; Nesterov, I.

106

Terahertz scattering by granular composite materials: An effective medium theory  

NASA Astrophysics Data System (ADS)

Terahertz (THz) spectroscopy and imaging have emerged as important tools for identification and classification of various substances, which exhibit absorption characteristics at distinct frequencies in the THz range. The spectral fingerprints can potentially be distorted or obscured by electromagnetic scattering caused by the granular nature of some substances. In this paper, we present THz time domain transmission measurements of granular polyethylene powders in order to investigate an effective medium theory that yields a parameterized model, which can be used to estimate the empirical measurements to good accuracy.

Kaushik, Mayank; Ng, Brian W.-H.; Fischer, Bernd M.; Abbott, Derek

2012-01-01

107

Chemical composition, digestibility, and voluntary feed intake of mango residues by sheep.  

PubMed

The chemical composition, digestibility, and voluntary feed intake by sheep of mango by-products were studied in an experiment with five dietary treatments consisting of mango peels and seed kernels, offered individually or together with urea block and a control. The mango residues were offered with rice straw and the control diet was straw only. Five groups of five male sheep of Djallonké type, 12-18 months old and weighing on average 18.6 kg were allocated randomly to the diets to assess the voluntary feed intake. Apparent digestibility of the same diets was measured using four sheep per diet. The mango residues were low in crude protein, 67 and 70 g/kg dry matter for the peels and the seed kernels, respectively. The content of neutral detergent fiber varied from 306 to 388 g/kg dry matter (DM) for the kernel and the peels, respectively. The kernel had relatively high level of fat (105 g/kg DM) and tannins (29 and 40 g/kg DM of hydrolysable and total tannins, respectively). The highest intake was observed with the diet containing both residues and urea block (741 g/day). The intake of kernels was lower in all diets when offered with the peels than when offered with rice straw alone. Apparent digestibility of the diets containing mango residues was 0.60-0.65. The peels and kernels had high digestibility coefficients (0.74 and 0.70, respectively). Based on the results above, it can be concluded that it would be interesting to test the residues in a growth experiment. PMID:23054805

Sanon, Hadja Oumou; Kanwe, Augustin B; Millogo, Alain; Ledin, Inger

2013-02-01

108

Insights into the chemical composition of Equisetum hyemale by high resolution Raman imaging  

Microsoft Academic Search

Equisetaceae has been of research interest for decades, as it is one of the oldest living plant families, and also due to\\u000a its high accumulation of silica up to 25% dry wt. Aspects of silica deposition, its association with other biomolecules, as\\u000a well as the chemical composition of the outer strengthening tissue still remain unclear. These questions were addressed by

Notburga Gierlinger; Lanny Sapei; Oskar Paris

2008-01-01

109

Combinatorial synthesis of inorganic or composite materials  

DOEpatents

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

Goldwasser, Isy (Palo Alto, CA); Ross, Debra A. (Mountain Ranch, CA); Schultz, Peter G. (La Jolla, CA); Xiang, Xiao-Dong (Danville, CA); Briceno, Gabriel (Baldwin Park, CA); Sun, Xian-Dong (Fremont, CA); Wang, Kai-An (Cupertino, CA)

2010-08-03

110

Composite Material Switches  

NASA Technical Reports Server (NTRS)

A device to protect electronic circuitry from high voltage transients is constructed from a relatively thin piece of conductive composite sandwiched between two conductors so that conduction is through the thickness of the composite piece. The device is based on the discovery that conduction through conductive composite materials in this configuration switches to a high resistance mode when exposed to voltages above a threshold voltage.

Javadi, Hamid (Inventor)

2001-01-01

111

Composite Material Switches  

NASA Technical Reports Server (NTRS)

A device to protect electronic circuitry from high voltage transients is constructed from a relatively thin piece of conductive composite sandwiched between two conductors so that conduction is through the thickness of the composite piece. The device is based on the discovery that conduction through conductive composite materials in this configuration switches to a high resistance mode when exposed to voltages above a threshold voltage.

Javadi, Hamid (Inventor)

2002-01-01

112

Computational Chemical Materials Engineering  

E-print Network

: Thermal barrier coatings, wear resistance coatings, radiation resistant materials · Materials for optical with usable ­ Chemical ­ Electronic ­ Optical ­ Magnetic ­ Transport, thermal and mechanical properties storage, conversion, transport: Catalysts, Thermoelectrics, polymer/solid oxide membranes · Coatings

113

Mechanics of Composite Materials  

Microsoft Academic Search

The mechanical behavior of composites is traditionally evaluated on both microscopic and macroscopic scale to take into account inhomogeneity. Micromechanics attempts to quantify the interactions of fiber and matrix (reinforcement and resin) on a microscopic scale on par with the diameter of a single fiber. Macromechanics treats composites as homogeneous materials, with mechanical properties representative of the laminate as a

Robert M. Jones

1999-01-01

114

Characterization and versatile applications of low hydrogen content SiOCN grown by plasma-enhanced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Low hydrogen content silicon oxycarbonitride (SiOCN) thin films were grown by plasma-enhanced chemical vapor deposition exploiting hydrogen dilution with silane/methane/nitrous oxide or tetramethylsilane/nitrous oxide precursors. The effects of deposition temperature were compared by investigating the compositional, optical, mechanical, and electrical properties of films grown at 100 °C, 250 °C, and 400 °C at thicknesses ranging from 50 nm to 10 ?m. The dielectric constant and high breakdown strength of the films remain relatively constant at between 4-5 and 6.8 ± 0.2 MV cm-1 to 9.1 ± 0.3 MV cm-1, respectively, despite the differences in deposition temperature. Other properties of the films include excellent transparency in the visible regime, high nanoindentation hardness (4 to 12 GPa), and relatively low measured stress on Si (-20 to -300 MPa). Overall, the results of this work show that these SiOCN films can be used in a wide variety of applications, including as a dielectric within high voltage capacitors, transparent abrasion-resistant coatings for plastic windows, coatings on flexible substrates, a metal diffusion barrier for low-k dielectrics and polymer films, or within various microelectronic fabrication steps or systems.

Hamm, Steven C.; Waidmann, Jacob; Mathai, Joseph C.; Gangopadhyay, Keshab; Currano, Luke; Gangopadhyay, Shubhra

2014-09-01

115

Production and application of chemical fibers with special properties for manufacturing composite materials and goods of different usage  

NASA Technical Reports Server (NTRS)

The development of modern technologies demands the creation of new nonmetallic, fibrous materials with specific properties. The fibers and materials developed by NII 'Chimvolokno', St. Petersburg, can be divided into two groups. The first group includes heat-resistant fibers, fire-resistant fibers, thermotropic fibers, fibers for medical application, and textile structures. The second group contains refractory fibers, chemoresistant and antifriction fibers, fibers on the basis of polyvinyl alcohol, microfiltering films, and paperlike and nonwoven materials. In cooperation with NPO 'Chimvolokno' MYTITSHI, we developed and started producing heat-resistant high-strength fibers on the base of polyhetarearilin and aromatic polyimides (SVM and terlon); heat-resistant fibers on the base of polyemede (aramid); fire-retardant fibers (togilen); chemoresistant and antifriction fibers on the basis of homo and copolymers of polytetrafluoroethylene (polyfen and ftorin); and water soluble, acetylated, and high-modulus fibers from polyvinyl alcohol (vylen). Separate reports will deal with textile structures and thermotropic fibers, as well as with medical fibers. One of the groups of refractory fibers carbon fibers (CF) and the corresponding paperlike nonwoven materials are discussed in detail. Also, composite materials (CM) and their base, which is the subject of the author's research since 1968, is discussed.

Levit, R.

1993-01-01

116

The Chemical Composition of Honey  

ERIC Educational Resources Information Center

Honey is a supersaturated sugar solution, created by bees, and used by human beings as a sweetener. However, honey is more than just a supersaturated sugar solution; it also contains acids, minerals, vitamins, and amino acids in varying quantities. In this article, we will briefly explore the chemical composition of honey. (Contains 2 figures and…

Ball, David W.

2007-01-01

117

Composite Aluminum-Copper Sheet Material by Friction Stir Welding and Cold Rolling  

NASA Astrophysics Data System (ADS)

An aluminum alloy and a pure copper material were butt-joined by friction stir welding and subsequently cold rolled. The cold-rolling operation proved to be very advantageous because small voids present after friction stir welding were closed, the interface area per material thickness was enlarged, a thin intermetallic layer was partitioned, and the joint was strengthened by strain hardening. Tensile test specimens fractured in the heat-affected zone in the aluminum material; tensile strengths of the joints exceeded the tensile strengths of the base materials and were as high as 335 MPa. During soft annealing of the composite material, a 6-8-?m-thick intermetallic layer was grown at the interface. Nevertheless, tensile fracture still occurred in the heat-affected zone of the aluminum material. Electrical resistivity of the joint was smaller than resistivity of the aluminum material. Production of such composite material would result in coiled sheet material that could be subjected to further treatments such as electroplating and forming operations in an efficient and economically viable manner. The new composite material is promising for emerging automotive and industrial electrical applications.

Kahl, S.; Osikowicz, W.

2013-08-01

118

Mulching effect of plant residues of chemically contrasting compositions on soil organic matter content and cation exchange capacity  

Microsoft Academic Search

Effects of five types of plant residues [Acioa, presently Dactyladenia barteri, Gliricidia sepium, and Leucaena lecocephala prunings, maize (Zea mays) stover and rice (Oryza sativa) straw] applied as mulch on soil organic matter (SOM) content and effective cation exchange capacity (ECEC) were studied on an Alfisol in the humid tropics. Plant residue mulch resulted in a decline in SOM and

G. Tian; L. Brussaard

1997-01-01

119

Proximate composition and caloric content of eight Lake Michigan fishes  

USGS Publications Warehouse

We measured the proximate composition (percentage lipid, water, fat-free dry material, ash) and caloric content of eight species of Lake Michigan fish: lake trout (Salvelinus namaycush), coho salmon (Oncorhynchus kisutch), lake whitefish (Coregonus clupeaformis), bloater (Coregonus hoyi), alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), deepwater sculpin (Myoxocephalus quadricornis), and slimy sculpin (Cottus cognatus). Except for alewives, proximate composition and caloric content did not differ significantly between males and females. And, for coho salmon, there was no significant difference in composition between fish collected in different years. Lipid and caloric content of lake trout increased directly with age. In all species examined, lipids and caloric contents were significantly lower in small, presumably immature, fish than in larger, older fish. Lipid content of lake trout, lake whitefish, and bloaters (range of means, 16-22%) was nearly 3 times higher than that of coho salmon, sculpins, rainbow smelt, and alewives (range of means, 5.2-7.0%). The mean caloric content ranged from 6.9 to 7.1 kcal/g for species high in lipids and from 5.8 to 6.3 kcal/g for species low in lipids. Although the caloric content of all species varied directly with lipid content and inversely with water content, an increase in lipid content did not always coincide with a proportional increase in caloric content when other components of fish composition were essentially unchanged. This observation suggests that the energy content of fish estimated from the proximate composition by using universal conversion factors may not necessarily be accurate.

Rottiers, Donald V.; Tucker, Robert M.

1982-01-01

120

Aqueous chemical wash compositions  

SciTech Connect

This patent describes an aqueous, substantially unfoamed chemical wash composition having properties making it suitable for use as a pre-flush in well cementing operations and/or for removal of drilling mud from a borehole at a temperature of from about 150/sup 0/F to about 270/sup 0/F, the wash a. being predominantly composed of water, b. containing an active surfactant component comprising a combination of (1) from about 0.1 to about 1.5 weight percent (total weight basis) of a water soluble anionic surfactant; (2) from about 0.1 to about 1.5 weight percent (total weight basis) of a nonionic surfactant; and (3) from about 0.05 to about 0.54 weight percent (total weight basis) of at least one water soluble amphoteric surfactant, and c. having dispersed therein a heterogeneous mixture of distinct particles comprising both a first particulate oil soluble resin which is friable and a second particulate oil soluble resin which is pliable and where the size of the friable resin particles ranges from about 0.5 to about 300 microns and the size of the pliable resin particles ranges from about 0.05 to about 30 microns. The amount of the friable-pliable resin mixture is sufficient to impart effective fluid loss control to the chemical wash composition.

Bannister, C.E.

1987-07-21

121

Standardized evaluation of chemical compositions of LiTaO3 single crystals for SAW devices using the LFB ultrasonic material characterization system.  

PubMed

The line-focus-beam ultrasonic material characterization (LFB-UMC) system is applied to compare and evaluate tolerances provided independently for the Curie temperature T(C) and lattice constant a to evaluate commercial LiTaO3 single crystals by measuring the Rayleigh-type leaky surface acoustic wave (LSAW) velocities V(LSAW). The relationships between V(LSAW), and T(C) and a measured by individual manufacturers were obtained experimentally using 42 degrees Y X-LiTaO3 wafers as specimens from three crystal manufacturers. In addition, the relationship between V(LSAW) and SH-type SAW velocities V(SAW) that are actually used for the SAW device wafers was obtained through calculations, using the chemical composition dependences of the acoustical physical constants for LiTaO3 crystals reported previously. The result of a comparison between the T(C) tolerance of +/-3 degrees C and the a tolerance of +/-0.00002 nm through the common scale of V(LSAW) or V(SAW) demonstrated that the a tolerance is 1.6 times larger than the T(C) tolerance. Furthermore, we performed a standardized comparison of statistical data of T(C) and a for LiTaO3 crystals grown by two manufacturers during 1999 and 2000, using V(LSAW). The results clarified the differences of the average chemical compositions and of the chemical composition distributions among the crystal ingots between the two manufacturers. A guideline for the standardized evaluation procedure has been established for the SAW-device wafer specifications by the LFB-UMC system. PMID:11989701

Kushibiki, Jun-ichi; Ohashi, Yuji; Ujiie, Takaaki

2002-04-01

122

Chemical Bonding in Composite SiNx/Diamond-Like Carbon Films Prepared by Filter Cathodic Arc Deposition of Graphite Incorporated with Radio Frequency Sputtering of Silicon Nitride  

NASA Astrophysics Data System (ADS)

SiNx and diamond-like carbon (DLC) films were prepared simultaneously on Si substrates by the RF magnetron sputtering of a silicon nitride (Si3N4) target and the filtered cathodic arc (FCA) deposition of graphite, respectively. The RF power was fixed at 100 W, while the arc current of graphite for the FCA deposition was varied from 20 to 80 A. The structure of composite SiNx/DLC films was investigated by Raman spectroscopy. The chemical composition and chemical state of the films were analyzed by X-ray photoelectron spectroscopy (XPS). Results revealed that the atomic concentration of carbon (C) increased, while those of silicon (Si) and nitrogen (N) decreased with increasing arc current. In addition, the sp3 content in the composite films was found to increase with the arc current. This result indicates that the structure and property of the composite films can be controlled according to their required applications by varying the arc current.

Bunnak, Phuwanai; Gong, Yongping; Limsuwan, Supanee; Pokaipisit, Artorn; Limsuwan, Pichet

2013-09-01

123

Growth of crystals of several boron-carbon compositions by chemical vapor deposition  

NASA Technical Reports Server (NTRS)

Boron-carbon compounds have been deposited by the flow of carbon tetrachloride and boron trichloride, in the presence of a large excess of hydrogen, over a graphite surface maintained at 1000-1300 C. Deposits were formed on either an RF-heated disc or a tube or insert heated by a resistance furnace. Crystalline materials ranging in composition from B2C to B17C have been obtained.

Kevill, D. N.; Rissmann, T. J.; Brewe, D.; Wood, C.

1986-01-01

124

Thermo-chemical fuel removal from porous materials by oxygen and nitrogen dioxide  

NASA Astrophysics Data System (ADS)

Thermo-chemical removal (TCR), or baking in reactive gases, is a candidate method to control the co-deposit related tritium inventory in fusion devices. TCR can be understood as reaction-diffusion processes in a porous material. O2-TCR was applied to 150-550 nm thick a-C:D layers with similar textures. A linear relation between the integral TCR rate and the layer thickness, as predicted by the understanding, was observed in the experiment, i.e. the time to remove the hydrogen inventory is independent of its initial amount. TCR with nitrogen dioxide (NO2) at temperatures of 200-350 °C was conducted with a set of a-C:D and W-C-H layers. At 350 °C NO2 removed ˜ 15% porosity a-C:D within 3 min. The O retention in remaining a-C:D was ? 1017 O cm-2. An activation energy of ? 0.78 eV for reactions of NO2 with D and C was determined. The results were applied for predictions of the TCR effectivity in ITER. The treatment of W-C-H led to O uptake (O/W ? 2-3), while W and C contents remained unchanged.

Möller, S.; Alegre, D.; Kreter, A.; Petersson, P.; Esser, H. G.; Samm, U.

2014-04-01

125

Microstructure and dielectric properties of silver-barium titanate nanocomplex materials by wet chemical approach  

NASA Astrophysics Data System (ADS)

To develop ceramic capacitors with a high effective dielectric constant, we attempted to fabricate BaTiO3 (BT) complexes with embedded Ag nanoparticles by wet chemical processes. Ag nanoparticle-adsorbed dendritic BT particles, Ag-BT hybrid particles, were synthesized from the sol-gel-derived precursor gel powders containing Ag, Ba, and Ti by hydrothermal treatment. These particles were pressed with BT fillers and TiO2 precursor nanoparticles into green compacts, and then, the green compacts were chemically converted into the Ag/BT nanocomplex compacts in Ba(OH)2 aqueous solution under the hydrothermal condition at 160 °C. The effective dielectric constant of the resultant Ag/BT nanocomplexes increases with an increase in Ag content. The maximal effective dielectric constant of approximately 900 was recorded for the nanocomplex with the Ag content of 10.7 vol %.

Ueno, Shintaro; Sakamoto, Yasunao; Nakashima, Kouichi; Wada, Satoshi

2014-09-01

126

Energetic composites and method of providing chemical energy  

DOEpatents

A method is described for providing chemical energy and energetic compositions of matter consisting of thin layers of substances which will exothermically react with one another. The layers of reactive substances are separated by thin layers of a buffer material which prevents the reactions from taking place until the desired time. The reactions are triggered by an external agent, such as mechanical stress or an electric spark. The compositions are known as metastable interstitial composites (MICs). This class of compositions includes materials which have not previously been capable of use as energetic materials. The speed and products of the reactions can be varied to suit the application. 3 figs.

Danen, W.C.; Martin, J.A.

1997-02-25

127

Energetic composites and method of providing chemical energy  

DOEpatents

A method for providing chemical energy and energetic compositions of matter consisting of thin layers of substances which will exothermically react with one another. The layers of reactive substances are separated by thin layers of a buffer material which prevents the reactions from taking place until the desired time. The reactions are triggered by an external agent, such as mechanical stress or an electric spark. The compositions are known as metastable interstitial composites (MICs). This class of compositions includes materials which have not previously been capable of use as energetic materials. The speed and products of the reactions can be varied to suit the application.

Danen, Wayne C. (Los Alamos, NM); Martin, Joe A. (Espanola, NM)

1997-01-01

128

Composite structural materials  

NASA Technical Reports Server (NTRS)

Progress and plans are reported for investigations of: (1) the mechanical properties of high performance carbon fibers; (2) fatigue in composite materials; (3) moisture and temperature effects on the mechanical properties of graphite-epoxy laminates; (4) the theory of inhomogeneous swelling in epoxy resin; (5) numerical studies of the micromechanics of composite fracture; (6) free edge failures of composite laminates; (7) analysis of unbalanced laminates; (8) compact lug design; (9) quantification of Saint-Venant's principles for a general prismatic member; (10) variation of resin properties through the thickness of cured samples; and (11) the wing fuselage ensemble of the RP-1 and RP-2 sailplanes.

Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

1983-01-01

129

Growth and characterization of group III nitride materials on (0001) sapphire by metalorganic chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Group III-nitrides are attractive materials for application to short wavelength optoelectronic devices and electronic devices. A lattice matched substrate for these materials is still not commercially available and they are generally grown on lattice substrates. In this work, heteroepitaxial growth of GaN and InGaN/GaN on (0001) sapphire substrates by atmospheric pressure metalorganic chemical vapor deposition (MOCVD) equipped with a close spaced showerhead reactor is studied. A multilayer buffer layer approach to GAN growth has been developed in which the thermal desorption and mass transport of low temperature buffer layer are minimized by deposition of successive layers at increased Formation and coalescence of GaN truncated three-dimensional islands (TTIs) are observed during the initial stage of overlayer growth on the low temperature grown buffer layer. We discovered that the density of TTIs is controllable by an NH3 flow rate and demonstrated the influence of the TTI size on the quality of the entire GaN film. During coalescence of TTIs, growth conditions that favor higher desorption of species on the GaN (0001) surface and incorporation on other planes are beneficial. On the other hand, after completion of the coalescence of the TTIs, growth conditions that give higher growth rate in the <0001> direction are favorable in order to suppress nitrogen vacancies in the film. Therefore, we introduced a multilayer overlayer approach in which growth conditions are altered as the growth mode changes. High quality GaN with featureless surface morphology has been grown on (0001) sapphire substrate by using this multilayer buffer layer and overlayer approach. Defect formation and In segregation in InGaN/GaN quantum wells grown at various temperatures and with various well thicknesses were studied. In 0.16Ga0.84N quantum wells with In compositional non-uniformity and a small number of structural defects originating at the InGaN/GaN interface showed sharp and intense InGaN emission in cathodoluminescence (CL). Increasing the In composition caused surface roughness in the InGaN layer and the formation of stacking faults/dislocations originating at InGaN/GaN interface. This resulted in a reduction of the InGAN emission peak intensity.

Kobayashi, Junko T.

130

Mechanics of interfacial composite materials.  

PubMed

Recent experiments and simulations have demonstrated that particle-covered fluid/fluid interfaces can exist in stable nonspherical shapes as a result of the steric jamming of the interfacially trapped particles. The jamming confers the interface with solidlike properties. We provide an experimental and theoretical characterization of the mechanical properties of these armored objects, with attention given to the two-dimensional granular state of the interface. Small inhomogeneous stresses produce a plastic response, while homogeneous stresses produce a weak elastic response. Shear-driven particle-scale rearrangements explain the basic threshold needed to obtain the near-perfect plastic deformation that is observed. Furthermore, the inhomogeneous stress state of the interface is exhibited experimentally by using surfactants to destabilize the particles on the surface. Since the interfacially trapped particles retain their individual characteristics, armored interfaces can be recognized as a kind of composite material with distinct chemical, structural, and mechanical properties. PMID:17107022

Subramaniam, Anand Bala; Abkarian, Manouk; Mahadevan, L; Stone, Howard A

2006-11-21

131

Origin and Bulk Chemical Composition of Mercury  

NASA Astrophysics Data System (ADS)

The planet Mercury is remarkable because its mean uncompressed density ˜5.3 g/cc implies a Fe-Ni mass content of ˜67%. This is more than twice the ˜32% metal fractions of Venus and Earth. This factor coupled with other marked chemical and isotopic differences between the four terrestrial planets points to the conclusion that each planet ?received the overwhelming majority of its mass from a narrow compositionally-distinct annulus of material around the Sun? (Drake & Righter 2002 Nature 416 39; Taylor & Scott 2001 in URL below). This situation finds an explanation within the Modern Laplacian theory of Solar system origin (Prentice 2001 Earth Moon & Planets 87 11; URL: www.lpi.usra.edu/meetings/mercury01). Here the planets condensed from a concentric family of circular gas rings shed by the proto-Solar cloud. The temperatures and mean orbit pressures of the gas rings scale with heliocentric distance r as T ~ 1/r0.9 and p ˜1/r4.0 respectively. At Mercury?s orbit T = 1640 K p= 0.16 bar and the three primary equilibrium condensates are Fe-Ni (67 %) gehlenite (26.1%) and spinel (4.1%). A simple 2-zone structural model of Mercury based on this mix has mean density 5.43 g/cc and axial moment-of-inertia coefficent C/MR2 = 0.325.

Prentice, Andrew J. R.; Jontof-Hutter, Daniel

2005-01-01

132

Mercury's Origin and Bulk Chemical Composition  

NASA Astrophysics Data System (ADS)

The planet Mercury is remarkable because its mean uncompressed density ~5.3 g/cc implies a Fe-Ni mass content of ~67%. This is more than twice the ~32% metal fractions of Venus and Earth. This factor coupled with other marked chemical and isotopic differences between the four terrestrial planets points to the conclusion that each planet ?received the overwhelming majority of its mass from a narrow compositionally-distinct annulus of material around the Sun? (Drake & Righter 2002 Nature 416 39; Taylor & Scott 2001 in URL below). This situation finds an explanation within the Modern Laplacian theory of Solar system origin (Prentice 2001 Earth Moon & Planets 87 11; URL: www.lpi.usra.edu/meetings/mercury01). Here the planets condensed from a concentric family of circular gas rings shed by the proto-Solar cloud. The temperatures and mean orbit pressures of the gas rings scale with heliocentric distance r as T ~ 1/r0.9 and p ~ 1/r4.0 respectively. At Mercury?s orbit T = 1640 K p= 0.16 bar and the three primary equilibrium condensates are Fe-Ni (67 %) gehlenite (26.1%) and spinel (4.1%). A simple 2-zone structural model of Mercury based on this mix has mean density 5.43 g/cc and axial moment-of-inertia coefficent C/MR2 = 0.325.

Prentice, Andrew J.; Jontof-Hutter, Daniel

133

Fabrication of Nanostructured Wc-Based Hard Materials with Different Contents of co by High Frequency Induction Heated Sintering  

NASA Astrophysics Data System (ADS)

Hard materials, in particular tungsten carbide (WC) hard material has been used in many industries as cutting tool and abrasive materials. For improving toughness, binders are added into carbide materials. The effect of Co as binder on the mechanical properties in the nanosized WC was discussed. The hardness and fracture toughness were also investigated using 30 kgf load Vickers indenter. The nanosized WC-8, 10 and 12 vol.% Co composites were successfully fabricated without grain growth by high frequency induction heated sintering (HFIHS), which is the rapid sintering method, due to short sintering time 1140°C. The nanosized WC-Co composites fabricated by HFIHS have better mechanical properties than WC-Co composite fabricated by commercial sintering.

Kang, Duck-Soo; Woo, Kee-Do; Kwon, Eui-Pyo; Kim, Sang-Hyuk; Moon, Min-Seok; Shon, In-Jin

134

Micromechanics simulations of the viscoelastic properties of highly filled composites by the material point method (MPM)  

NASA Astrophysics Data System (ADS)

Viscoelastic properties of the highly filled plastic-bonded explosive PBX-9501 were studied by two-dimensional dynamic material point method (MPM) simulations utilizing plasticized polymer binder and crystalline HMX constituent properties taken from experiment. The upper bound for the composite properties was estimated from iso-displacement boundary conditions, whereas the lower bound was estimated from iso-stress boundary conditions. A homogenized or 'dirty' binder approach was utilized to handle the multiple length scales involved in MPM simulations of highly filled composites with a broad distribution of filler particle sizes. Multiple time scale challenges were addressed by conducting a series of simulations in which the speed of sound of the composite was systematically varied by adjusting material point masses. This approach was used to predict the homogenized time dependent shear modulus of PBX-9501 from nanoseconds to milliseconds yielding good agreement with experimental data.

Xue, Liping; Borodin, Oleg; Smith, Grant D.; Nairn, John

2006-06-01

135

Chemical compositions of large cluster IDPs  

SciTech Connect

We performed X-ray fluorescence spectroscopy on two large cluster IDPs, which sample the IDP parent body at a mass scale two orders-of-magnitude larger than {approx}10 {micro}m IDPs, allowing proper incorporation of larger mineral grains into the bulk composition of the parent body. We previously determined that {approx}10 {micro}m interplanetary dust particles (IDPs) collected from the Earth's stratosphere are enriched in many moderately volatile elements by a factor of {approx}3 over the CI meteorites. However, these IDP measurements provide no direct constraint on the bulk chemical composition of the parent body (or parent bodies) of the IDPs. Collisions are believed to be the major mechanism for dust production by the asteroids, producing dust by surface erosion, cratering and catastrophic disruption. Hypervelocity impact experiments at {approx}5 km/sec, which is the mean collision velocity in the main belt, performed by Flynn and Durda on ordinary chondrite meteorites and the carbonaceous chondrite meteorite Allende show that the 10 {micro}m debris is dominated by matrix material while the debris larger than {approx}25 {micro}m is dominated by chondrule fragments. Thus, if the IDP parent body is similar in structure to the chondritic meteorites, it is likely that the {approx}10 {micro}m IDPs oversample the fine-grained component of the parent body. We have examined the matrix material from the few meteorites that are sufficiently fine-grained to be samples of potential IDP parent bodies. This search has, thus far, not produced a compositional and mineralogical match to either the hydrous or anhydrous IDPs. This result, coupled with our recent mapping of the element distributions, which indicates the enrichment of moderately volatile elements is not due to contamination on their surfaces, suggests the IDPs represent a new type of extraterrestrial material. Nonetheless, the meteorite fragmentation results suggest that compositional measurements on 10 {micro}m IDPs only provide a direct constraint on the bulk chemical composition of the IDP parent body if the size-scale of the grains in the parent body is <<10 {micro}m. The stratospheric collections include many nonchondritic, mono-mineralic grains, collected along with the fine-grained chondritic IDPs. Some of these grains, which include volatile-poor olivine and pyroxene as well as calcophile-rich sulfides, have fine-grained, chondritic material (i.e., small bits of typical IDPs) adhering to their surfaces. This indicates that at least some of the non-chondritic grains found on the stratospheric collectors are fragments from the same parent as the fine-grained IDPs. Thus, the bulk composition of the IDP parent body can only be reconstructed by adding to the fine-grained, chondritic IDPs the correct amount of this non-chondritic material. Qualitatively, the addition of olivines and pyroxenes will reduce the mean content of many moderately volatile elements while the addition of sulfides will increase the content of some of these elements. However, the quantitative task of adding these monomineralic grains to the fine-grained IDPs cannot be accomplished by simply adding the non-chondritic material in proportion to its occurrence on the stratospheric collectors because: (1) it is not clear that all of the olivines, pyroxenes, sulfides or other mineral grains found on the stratospheric collectors are extraterrestrial; (2) the settling rate of a particle depends on its density and shape, thus the concentration factor for these high-density, mono-mineralic grains is lower at the collection altitude than it is for the lower-density, fine-grained aggregate IDPs; and (3) the atmospheric entry survival of a particle is a function of density, so higher density grains (e.g., sulfides) are more likely to vaporize on entry, even if they enter with the same velocity as fine-grained, lower-density aggregates. The collection of 'cluster IDPs,' which enter the atmosphere as large particles, some larger than 50 {micro}m in diameter, containing both fine-grained aggregate material

Flynn, G.J.; Lanzirotti, A.; Sutton, S.R. (SUNYP); (UC)

2006-12-06

136

A comparison of composition and emulsifying properties of MFGM materials prepared from different dairy sources by microfiltration.  

PubMed

Milk fat globule membrane (MFGM), due to its specific nature and composition, is known as material possessing advantageous nutritional as well as technological properties. In this study MFGM materials were produced from several dairy sources such as buttermilk (BM), butter serum (BS) and buttermilk whey (BMW) by microfiltration (MF). The obtained materials, depending on the sources, were called BM-MFGM, BS-MFGM and BMW-MFGM, respectively. The compositions of starting materials and the isolated MFGM materials as well as their emulsifying properties were analyzed and compared. As expected, the MF resulted in enrichment of polar lipids (PLs), major components of MFGM. On dry matter basis, BM-MFGM and BS-MFGM were about 2.5 times higher in PLs compared to their beginning materials while BMW-MFGM was about 8.3 times compared to buttermilk powder (BMP). Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that the microfiltered products still contained a high amount of non-MFGM proteins such as caseins, ?-lactoglobulin, and ?-lactalbumin. Emulsions of 35% soya oil in water were prepared with the mentioned materials using a homogenizer at various pressures. Generally, emulsions prepared with BMP and butter serum powder had significantly higher particle sizes than those prepared with the MFGM materials. This result along with microscopy observation and viscosity measurement indicated the presence of aggregated particles in the former emulsions, probably as a result of lack of surface-active components. The differences in composition, especially in content of PLs and proteins of the materials were the main reasons for the differences in their emulsifying behaviors. PMID:23751553

Miocinovic, Jelena; Le Trung, Thien; Fredrick, Eveline; Van der Meeren, Paul; Pudja, Predrag; Dewettinck, Koen

2014-09-01

137

Influences of carbon content and coating carbon thickness on properties of amorphous CoSnO3@C composites as anode materials for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

A series of core-shell carbon coated amorphous CoSnO3 (CoSnO3@C) with different carbon content are synthesized. Effects of carbon content and coating carbon thickness on the physical and electrochemical performances of the samples were studied in detail. The samples were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), galvanostatic charge-discharge and AC impedance spectroscopy, respectively. The results indicate that controlling the concentration of aqueous glucose solution influences the generation of in-situ carbon layer thickness. The optimal concentration of aqueous glucose solution, carbon content and carbon layer thickness are suggested as 0.25 M, 35.1% and 20 nm, respectively. CoSnO3@C composite prepared under the optimal conditions exhibits excellent cycling performance, whose reversible capacity could reach 491 mA h g-1 after 100 cycles.

Fan, Fuqiang; Fang, Guoqing; Zhang, Ruixue; Xu, Yanhui; Zheng, Junwei; Li, Decheng

2014-08-01

138

The red alga Bonnemaisonia asparagoides regulates epiphytic bacterial abundance and community composition by chemical defence.  

PubMed

Ecological research on algal-derived metabolites with antimicrobial activity has recently received increased attention and is no longer only aimed at identifying novel natural compounds with potential use in applied perspectives. Despite this progress, few studies have so far demonstrated ecologically relevant antimicrobial roles of algal metabolites, and even fewer have utilized molecular tools to investigate the effects of these metabolites on the natural community composition of bacteria. In this study, we investigated whether the red alga Bonnemaisonia asparagoides is chemically defended against bacterial colonization of its surface by extracting surface-associated secondary metabolites and testing their antibacterial effects. Furthermore, we compared the associated bacterial abundance and community composition between B. asparagoides and two coexisting macroalgae. Surface extracts tested at natural concentrations had broad-spectrum effects on the growth of ecologically relevant bacteria, and consistent with this antibacterial activity, natural populations of B. asparagoides had significantly lower densities of epibacteria compared with the coexisting algae. Terminal restriction fragment length polymorphism analysis further showed that B. asparagoides harboured surface-associated bacteria with a community composition that was significantly different from those on coexisting macroalgae. Altogether, these findings demonstrate that B. asparagoides produces surface-bound antibacterial compounds with a significant impact on the abundance and composition of the associated bacterial community. PMID:19878319

Nylund, Göran M; Persson, Frank; Lindegarth, Mats; Cervin, Gunnar; Hermansson, Malte; Pavia, Henrik

2010-01-01

139

Chemical composition mapping with nanometre resolution by soft X-ray microscopy  

NASA Astrophysics Data System (ADS)

X-ray microscopy is powerful in that it can probe large volumes of material at high spatial resolution with exquisite chemical, electronic and bond orientation contrast. The development of diffraction-based methods such as ptychography has, in principle, removed the resolution limit imposed by the characteristics of the X-ray optics. Here, using soft X-ray ptychography, we demonstrate the highest-resolution X-ray microscopy ever achieved by imaging 5?nm structures. We quantify the performance of our microscope and apply the method to the study of delithiation in a nanoplate of LiFePO4, a material of broad interest in electrochemical energy storage. We calculate chemical component distributions using the full complex refractive index and demonstrate enhanced contrast, which elucidates a strong correlation between structural defects and chemical phase propagation. The ability to visualize the coupling of the kinetics of a phase transformation with the mechanical consequences is critical to designing materials with ultimate durability.

Shapiro, David A.; Yu, Young-Sang; Tyliszczak, Tolek; Cabana, Jordi; Celestre, Rich; Chao, Weilun; Kaznatcheev, Konstantin; Kilcoyne, A. L. David; Maia, Filipe; Marchesini, Stefano; Meng, Y. Shirley; Warwick, Tony; Yang, Lee Lisheng; Padmore, Howard A.

2014-10-01

140

Characterization and chemical composition of fatty acids content of watermelon and muskmelon cultivars in Saudi Arabia using gas chromatography/mass spectroscopy  

PubMed Central

Background: The growth in the production of biodiesel, which is principally fatty acid methyl esters (FAME), has been phenomenal in the last ten years because of the general desire to cut down on the release of greenhouse gases into the atmosphere, and also as a result of the increasing cost of fossil fuels. Objective: Establish whether there is any relationship between two different species (watermelon and muskmelon) within the same family (Cucurbitaceae) on fatty acid compositions and enumerate the different fatty acids in the two species. Materials and Methods: Extraction of fatty acids from the two species and preparation the extract to gas chromatography/mass spectroscopy analysis to determine the fatty acids compositions qualitatively and quantitatively. Results: The analyzed plants (watermelon and muskmelon) contain five saturated fatty acids; tetrdecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid and octadecanoic acid with different concentrations, while muskmelon contains an extra saturated fatty acid named eicosanoic acid. The watermelon plant contains five unsaturated fatty acids while muskmelon contains three only, the two plants share in two unsaturated fatty acids named 9-hexadecenoic acid and 9-octadecenoic acid, the muskmelon plant contains higher amounts of these two acids (2.04% and 10.12%, respectively) over watermelon plant (0.88% and 0.25%, respectively). Conclusion: The chemical analysis of watermelon and muskmelon revealed that they are similar in saturated fatty acids but differ in unsaturated fatty acids which may be a criterion of differentiation between the two plants. PMID:23661995

Albishri, Hassan M.; Almaghrabi, Omar A.; Moussa, Tarek A. A.

2013-01-01

141

Thermoplastic constructional composite material for radiation protection  

Microsoft Academic Search

The possibility of synthesis of filled metallooligomer powders on the basis of lead ethylsiliconate is considered by a method\\u000a of heterophase interaction, in siloksan chains of which chemically bound lead with a high concentration of atoms of lead is\\u000a contained. Thermoplastic constructional composite materials for radiation protection on the basis of a polystyrene polymeric\\u000a matrix modified by waterproof oligomer lead

V. I. Pavlenko; I. S. Epifanovskii; R. N. Yastrebinskii; O. V. Kuprieva

2011-01-01

142

Treatment of chemical warfare agents by zero-valent iron nanoparticles and ferrate(VI)/(III) composite.  

PubMed

Nanoscale zero-valent iron (nZVI) particles and a composite containing a mixture of ferrate(VI) and ferrate(III) were prepared by thermal procedures. The phase compositions, valence states of iron, and particle sizes of iron-bearing compounds were determined by combination of X-ray powder diffraction, Mössbauer spectroscopy and scanning electron microscopy. The applicability of these environmentally friendly iron based materials in treatment of chemical warfare agents (CWAs) has been tested with three representative compounds, sulfur mustard (bis(2-chlorethyl) sulfide, HD), soman ((3,3'-imethylbutan-2-yl)-methylphosphonofluoridate, GD), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothiolate (VX). Zero-valent iron, even in the nanodimensional state, had a sluggish reactivity with CWAs, which was also observed in low degrees of CWAs degradation. On the contrary, ferrate(VI)/(III) composite exhibited a high reactivity and complete degradations of CWAs were accomplished. Under the studied conditions, the estimated first-order rate constants (? 10(-2)s(-1)) with the ferrate(VI)/(III) composite were several orders of magnitude higher than those of spontaneous hydrolysis of CWAs (10(-8)-10(-6)s(-1)). The results demonstrated that the oxidative technology based on application of ferrate(VI) is very promising to decontaminate CWAs. PMID:22119195

Zboril, Radek; Andrle, Marek; Oplustil, Frantisek; Machala, Libor; Tucek, Jiri; Filip, Jan; Marusak, Zdenek; Sharma, Virender K

2012-04-15

143

Aerogel/polymer composite materials  

NASA Technical Reports Server (NTRS)

The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Roberson, Luke B. (Inventor); Clayton, LaNetra M. (Inventor)

2010-01-01

144

Supplemental Material Table of Contents  

E-print Network

1 Supplemental Material Table of Contents Text on the multiple individuals per population phylogeny: pg 4 Supplemental Figure 1: Phylogram of U. stansburiana populations from the complete data set that included multiple individuals per population. pg 5 Supplemental Table 1: Population locations and years

Kuchta, Shawn R.

145

Evaluation of moisture content in porous material by dynamic energy balance  

Microsoft Academic Search

The aim of this paper is to describe a procedure to evaluate the moisture content in porous medium by a non-destructive test. The method is based on the determination of the target thermal inertia by means of the measure of the energy input and the corresponding temperature increase, both obtained by 2-D optical sensors. Since the thermal inertia is strongly

Ermanno G. Grinzato; Chiara Bressan; Paolo G. Bison; Andrea Mazzoldi; Paolo Baggio; Cesare Bonacina

1992-01-01

146

Retention of organic and inorganic chemicals by the drainage/supply piping material.  

PubMed

A critical issue facing the turfgrass industry is the environmental fate and transport of organic and inorganic chemicals used on golf courses. The fate and distribution of those chemicals are strongly influenced by sorptive interactions with soil and sediment. In this study, the drainage and water supply piping material (used for construction of a prototype encapsulated golf green) was utilized to determine its potential sorption of three organic chemicals [2,4-dichloro-phenoxyacetic acid] (2,4-D), naphthalene and toluene and nitrate. Crushed piping material (small-to-large particle sizes) was evaluated. Isotherms were constructed using a batch equilibration technique. The results showed that the drainage/supply piping material at small particle sizes (<2.5 mm) has higher sorptive ability compared to soil (1.7 for 2,4-D and 13.4 for naphthalene). The K(F) value was 44, 253 and 70 for 2,4-D, naphthalene and toluene, respectively. K(oc) values were much higher than those of peat and soil at lower equilibrium concentrations. However, sorption decreased dramatically with increasing particle size (approaching zero at particle size 10 mm), due to reduction of surface areas and sorption sites. Sorption of NO(3)-N by the piping material was negligible. We concluded that sorption by intact drainage/supply piping material would not affect the recycling efficiency of pesticides and nutrients in the constructed encapsulated green. Conversely, drainage/supply piping material particles smaller than 2.5 mm in diameter can effectively be utilized as a filtering material. PMID:15092935

Li, K; Torello, W A; Xing, B

2000-06-01

147

Investigation of the chemical composition of meteorites by an activation method using a microtron  

NASA Astrophysics Data System (ADS)

The feasibility of using bremsstrahlung and photoneutrons from a microtron to measure the chemical composition of stony and iron meteorites is demonstrated. Conditions are established for the activation determination of approximately 20 elements in meteorite samples without their destruction. The optimal geometry and mode of irradiation are established; the contribution of competing reactions is calculated; and the limits and errors of the measurements are assessed. The chemical composition of the following meteorites was determined: the chondrites Zhovtnevyi Khutor (H5), Tsarev (L5), Kunashak (L5), Allende (CV3); the achondrites Norton County (Au) and Chervonyi Kut (Eu); and the iron meteorite Sikhote-Alin.

Kolesov, G. M.; Ernandes, A.

148

Original article Anatomy and chemical composition  

E-print Network

Original article Anatomy and chemical composition of Pinus pinea L. bark Elsa Nunesa Teresa Quilhób and axial and radial parenchyma, but no fibres. Resin ducts are present in fusiform rays. Styloid crystals-walled cells with inclu- sions and sometimes a layer of expanded cells. Ash content of P. pinea bark is low

Paris-Sud XI, Université de

149

Aligned Carbon Nanotube Reinforced Silicon Carbide Composites by Chemical Vapor Infiltration  

SciTech Connect

Owing to their exceptional stiffness and strength1 4, carbon nanotubes (CNTs) have long been considered to be an ideal reinforcement for light-weight, high-strength, and high-temperature-resistant ceramic matrix composites (CMCs)5 10. However, the research and development in CNT-reinforced CMCs have been greatly hindered due to the challenges related to manufacturing including poor dispersion, damages during dispersion, surface modification, densification and sintering, weak tube/matrix interfaces, and agglomeration of tubes at the matrix grain boundaries5,11. Here we report the fabrication of high-quality aligned CNT/SiC composites by chemical vapor infiltration (CVI), a technique that is being widely used to fabricate commercial continuous-filament CMCs12 15. Using the CVI technique most of the challenges previously encountered in the fabrication of CNT composites were readily overcome. Nanotube pullouts, an important toughening mechanism for CMCs, were consistently observed on all fractured CNT/SiC samples. Indeed, three-point bending tests conducted on individual CNT/SiC nanowires (diameters: 50 200 nm) using an atomic force microscope show that the CNT-reinforced SiC nanowires are about an order of magnitude tougher than the bulk SiC. The tube/matrix interface is so intimate and the SiC matrix is so dense that a ~50-nm-thick SiC coating can effectively protect the inside nanotubes from being oxidized at 1600 C in air. The CVI method may be extended to produce nanotube composites from a variety of matrix

Gu, Zhan Jun [University of Georgia, Athens, GA; Yang, Ying Chao [University of South Carolina, Columbia; Li, Kai Yuan [University of Georgia, Athens, GA; Tao, Xin Yong [University of South Carolina, Columbia; Eres, Gyula [ORNL; Howe, Jane Y [ORNL; Zhang, Li Tong [Northwestern Polytechnical University, Xi'an, China; Li, Xiao Dong [University of South Carolina, Columbia; Pan, Zhengwei [ORNL

2011-01-01

150

Advanced composite materials and processes  

NASA Technical Reports Server (NTRS)

Composites are generally defined as two or more individual materials, which, when combined into a single material system, results in improved physical and/or mechanical properties. The freedom of choice of the starting components for composites allows the generation of materials that can be specifically tailored to meet a variety of applications. Advanced composites are described as a combination of high strength fibers and high performance polymer matrix materials. These advanced materials are required to permit future aircraft and spacecraft to perform in extended environments. Advanced composite precursor materials, processes for conversion of these materials to structures, and selected applications for composites are reviewed.

Baucom, Robert M.

1991-01-01

151

Chemical composition of the wax secreted by a scale insect (Ceroplastes pseudoceriferus Green).  

PubMed

The wax material in the secretion of a scale insect,Ceroplastes pseudoceriferus Green was analyzed chemically with special interest to the composition of higher fatty acids and higher alcohols. The wax consists of 34.2% fatty acids, 27.1% unsaponifiable matter and 29.5% resin acids. The fatty acids were found to be a complex mixture of 15 normal acids ranging from C(8) to C(32). Of these, octacosanoic, triacontanoic and dotriacontanoic acids comprise over 30% of the wax. Presence of relatively large amount of unsaturated fatty acids of the C(18) series (2.8% of the wax) is of particular interest.From the unsaponifiable fraction, only one saturated straight chain aleohol, bexacosanol, was detected (2.7% of the original wax). The other unsaponifiable matter was considered to be cyclic or branched carbon chain, and consisted of at least 12 to 20 compounds. The resin acid fraction was also found to be a complex mixture of at least 13 to 14 components. PMID:17805590

Tamaki, Y

1966-09-01

152

Microstructure and mechanical characteristics of VT1-0-Based composite material reinforced by titanium monoboride  

NASA Astrophysics Data System (ADS)

The microstructure and mechanical characteristics of commercially pure titanium, i.e., the VT1-0 alloy, modified by 1.5 wt % B have been studied. It has been found that, during the melting of an ingot, uniformly distributed titanium monoboride (TiB) fibers up to Ø5 × 150 ?m in size appear in the material in a volume fraction of about 8%. The results of compressive and tensile tests show that this composite material substantially surpasses pure titanium in the strength characteristics, with retaining satisfactory plasticity.

Gaisina, E. R.; Gaisin, R. A.; Imayev, V. M.; Imayev, R. M.

2013-07-01

153

The Chemical Composition of Some Texas Soils.  

E-print Network

TEXAS AGRICULTURAL ESPERlMENT STATIONS. ______-_________- _-__---- - -. - _ _._ __ BULLETlN NO. 100. Chemical Section, Dec., 1907. The Chemical Composition of Some Texas Soils BY G. S. FRAPS, 'Ph. D., Chemist. POSTOFFICE COLLEGE STATION.... The postoffice address is College, Station, Texas. Reports and bulletins are sent free upon application to the Director. THE CHEMICAL COMPOSITION OF SOME TEXAS SOILS. BY G. S. FRAPS. This bulletin is a popular account of a study of a nnmber of Texas soils...

Fraps, G. S. (George Stronach)

1907-01-01

154

A study of the chemical composition of crude cottonseed oil and cake as influenced by variation in the method of adding moisture  

E-print Network

A STUDY OF THE CHEMICAL COMPOSITION OF CRUDE COTTONSEED OIL AND CAKE AS INFLUENCED BY VARIATION IN THE METHOD OF ADDING MOISTURE Landis Clyde Baker June, lQM Approval as to style and content recommended' ea 0 Depar en o stry and Chenical... IN THE METHOD OF ADDING MOISTURE A THESIS Submitted to the Faculty of the Agricultural and Mechanical College oi' Texas Partial Fulfillment of the Requirements of' the Degree of Raster of Science Na)or Sub)est& Chemical Engineering Landis Clyde Baker t...

Baker, Landis Clyde

2012-06-07

155

The foliar endophytic fungal community composition in Cirsium arvense is affected by mycorrhizal colonization and soil nutrient content.  

PubMed

Foliar fungal endophytes are ubiquitous, but understudied symbionts of most plant species; relatively little is known about the factors affecting their occurrence, diversity and abundance. We tested the effects of soil nutrient content and arbuscular mycorrhizal (AM) colonization on the occurrence of foliar endophytic fungi in Cirsium arvense in two field studies. In the first study, we assessed relationships between soil moisture, organic matter, carbon and nitrogen content and plant water, nitrogen and carbon content and AM colonization and the occurrence of foliar endophytic fungal species. In the second study, we manipulated soil nutrient content and AM colonization of potted seedlings and identified differences in endophytic fungal species composition of the leaves and stems. The results reveal that endophytes can occur either more or less frequently, depending on soil nutrient and plant water content and AM colonization. We propose that these patterns were the result of differences in fungal growth responses to nutrient availability in the leaves, which can be affected by resources obtained from the soil or symbiotic fungi in the roots. PMID:21036343

Eschen, René; Hunt, Stephanie; Mykura, Charlotte; Gange, Alan C; Sutton, Brian C

2010-01-01

156

Enhanced Removal of Lead by Chemically and Biologically Treated Carbonaceous Materials  

PubMed Central

Hybrid sorbents and biosorbents were synthesized via chemical and biological treatment of active carbon by simple and direct redox reaction followed by surface loading of baker's yeast. Surface functionality and morphology of chemically and biologically modified sorbents and biosorbents were studied by Fourier Transform Infrared analysis and scanning electron microscope imaging. Hybrid carbonaceous sorbents and biosorbents were characterized by excellent efficiency and superiority toward lead(II) sorption compared to blank active carbon providing a maximum sorption capacity of lead(II) ion as 500??mol?g?1. Sorption processes of lead(II) by these hybrid materials were investigated under the influence of several controlling parameters such as pH, contact time, mass of sorbent and biosorbent, lead(II) concentration, and foreign ions. Lead(II) sorption mechanisms were found to obey the Langmuir and BET isotherm models. The potential applications of chemically and biologically modified-active carbonaceous materials for removal and extraction of lead from real water matrices were also studied via a double-stage microcolumn technique. The results of this study were found to denote to superior recovery values of lead (95.0–99.0 ± 3.0–5.0%) by various carbonaceous-modified-bakers yeast biosorbents. PMID:22629157

Mahmoud, Mohamed E.; Osman, Maher M.; Ahmed, Somia B.; Abdel-Fattah, Tarek M.

2012-01-01

157

Insights into the chemical composition of Equisetum hyemale by high resolution Raman imaging.  

PubMed

Equisetaceae has been of research interest for decades, as it is one of the oldest living plant families, and also due to its high accumulation of silica up to 25% dry wt. Aspects of silica deposition, its association with other biomolecules, as well as the chemical composition of the outer strengthening tissue still remain unclear. These questions were addressed by using high resolution (<1 microm) Confocal Raman microscopy. Two-dimensional spectral maps were acquired on cross sections of Equisetum hyemale and Raman images calculated by integrating over the intensity of characteristic spectral regions. This enabled direct visualization of differences in chemical composition and extraction of average spectra from defined regions for detailed analyses, including principal component analysis (PCA) and basis analysis (partial least square fit based on model spectra). Accumulation of silica was imaged in the knobs and in a thin layer below the cuticula. In the spectrum extracted from the knob region as main contributions, a broad band below 500 cm(-1) attributed to amorphous silica, and a band at 976 cm(-1) assigned to silanol groups, were found. From this, we concluded that these protrusions were almost pure amorphous, hydrated silica. No silanol group vibration was detected in the silicified epidermal layer below and association with pectin and hemicelluloses indicated. Pectin and hemicelluloses (glucomannan) were found in high levels in the epidermal layer and in a clearly distinguished outer part of the hypodermal sterome fibers. The inner part of the two-layered cells revealed as almost pure cellulose, oriented parallel along the fiber. PMID:18057960

Gierlinger, Notburga; Sapei, Lanny; Paris, Oskar

2008-04-01

158

Comparison of the structural and chemical composition of two unique micro/nanostructures produced by femtosecond laser interactions on nickel  

SciTech Connect

The structural and chemical composition of two unique microstructures formed on nickel, with nanoscale features, produced using femtosecond laser surface processing (FLSP) techniques is reported in this paper. These two surface morphologies, termed mounds and nanoparticle-covered pyramids, are part of a larger class of self-organized micro/nanostructured surfaces formed using FLSP. Cross-sections of the structures produced using focused ion beam milling techniques were analyzed with a transmission electron microscope. Both morphologies have a solid core with a layer of nanoparticles on the surface. Energy dispersive X-ray spectroscopy by scanning transmission electron microscopy studies reveal that the nanoparticles are a nickel oxide, while the core material is pure nickel.

Zuhlke, Craig A.; Anderson, Troy P.; Alexander, Dennis R. [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)] [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)

2013-09-16

159

Chemical composition of the continental crust as revealed by studies in East China  

NASA Astrophysics Data System (ADS)

We report abundances of sixty-three major, trace, and rare earth elements in the upper crust in five tectonic units (the interior and southern margin of the North China craton, the North and South Qinling orogenic belts, and the Yangtze craton) of central East China and the study area as a whole. The estimates are based on sampling of 11,451 individual rock samples over an area of 950,000 km 2, from which 905 large composite samples were prepared and analyzed by thirteen methods. Some of the trace elements (i.e., Ag, As, Ge, Mo, Pd, Pt, Sb, Se, Sn, W) have never been subjected to systematic analysis in previous regional crustal composition studies. The middle, lower, and total crust compositions of the tectonic units are also estimated from studies of exposed crustal cross-sections and granulite xenoliths and by correlation of seismic data from eleven regional seismic refraction profiles with lithologies. The proposed granodioritic total crust composition has the following ratios of element pairs exhibiting similar compatibility, that are identical or close to the primitive mantle values: Zr/Hf = 37, Nb/Ta = 17.5, Ba/Th = 87, K/Pb = 0.12 × 10 4, Rb/Cs = 25, Ba/Rb = 8.94, Sn/Sm = 0.31, Se/Cd = 1.64, La/As = 10.3, Ce/Sb = 271, Pb/Bi = 57, Rb/Tl = 177, Er/Ag = 52, Cu/Au = 3.2×10 4, Sm/Mo = 7.5, Nd/W = 40, Cl/Li = 10.8, F/Nd = 21.9, and La/B = 1.8. The ? ( 238U/ 204Pb) value is calculated at ˜5. The upper crust composition is less evolved and higher in TiO 2, total FeO, Co, Cr, Ni, Sc and V, and lower in Na 2O, K 2O and Nb, Ta, Rb, Th, U, and Zr, than previous estimates based on shield samplings. Because usually the uppermost layer of the crust, where mafic volcanics tend to concentrate, has been removed from Precambrian shields, and since our study involves Phanerozoic orogenic belts, the results are suggested to be better representative of the upper crust in a general sense. Trace elements associated with mineralization (e.g., B, Cl, Se, As, Bi, Pd, W, Th, Cs, Ta, Tl, Hg, Au, and Pb) show considerable inter-unit variations by a factor of 2-5 in the upper crust. In addition, the North Qinling paleoactive margin is characterized by anomalous enrichment in Th, U, and Pb in particular and has a marked lower ? value (3.3) compared to the two cratons and the South Qinling paleopassive margin (? = 4.5-6.2). Each tectonic unit has a relatively homogenous middle crust composition which is broadly similar to the composition of the total crust. The lower crust in East China can be divided into two layers both seismically and chemically. The upper lower crust is characterized by Vp = 6.7 km s -1 and an intermediate composition and the lowermost crust by Vp = 7.1 km s -1 and a mafic composition. The bulk lower crust is still intermediate in composition with 58% SiO 2 due to the dominance of the upper lower crust. P-wave velocities of both the lower and total crusts in East China are slower by 0.2-0.4 km s -1 compared to various global estimates. Correspondingly, the total crust shows an more evolved composition and is characterized by a significant negative Eu anomaly (Eu/Eu? = 0.80), low Sr/Nd (10.4), and high La/Nb (3.0) ratios. The obtained SiO 2 is 64% on a volatile-free basis. The near arc magma La/Nb ratio implies that intraplate crustal growth contributes <10% of the continental crust. The relative deficits in Eu, Sr, and transition metals (Cr, Ni, Co, V, and Ti) in the derived crustal compositions of East China, along with slower crustal velocity and thin crustal thickness for the Paleozoic to Mesozoic Qinling-Dabie-Sulu orogenic belt, strongly suggest that lower crust delamination of eclogites, as represented by those from the Dabie-Sulu belt, had played an important role in modification of the East China crust during the Phanerozoic era.

Gao, Shan; Luo, Ting-Chuan; Zhang, Ben-Ren; Zhang, Hong-Fei; Han, Yin-wen; Zhao, Zi-Dan; Hu, Yi-Ken

1998-06-01

160

Chemical composition of the continental crust as revealed by studies in East China  

NASA Astrophysics Data System (ADS)

We report abundances of sixty-three major, trace, and rare earth elements in the upper crust in five tectonic units (the interior and southern margin of the North China craton, the North and South Qinling orogenic belts, and the Yangtze craton) of central East China and the study area as a whole. The estimates are based on sampling of 11,451 individual rock samples over an area of 950,000 km 2 , from which 905 large composite samples were prepared and analyzed by thirteen methods. Some of the trace elements (i.e., Ag, As, Ge, Mo, Pd, Pt, Sb, Se, Sn, W) have never been subjected to systematic analysis in previous regional crustal composition studies. The middle, lower, and total crust compositions of the tectonic units are also estimated from studies of exposed crustal cross-sections and granulite xenoliths and by correlation of seismic data from eleven regional seismic refraction profiles with lithologies. The proposed granodioritic total crust composition has the following ratios of element pairs exhibiting similar compatibility, that are identical or close to the primitive mantle values: Zr/Hf = 37, Nb/Ta = 17.5, Ba/Th = 87, K/Pb = 0.12 × 10 4 , Rb/Cs = 25, Ba/Rb = 8.94, Sn/Sm = 0.31, Se/Cd = 1.64, La/As = 10.3, Ce/Sb = 271, Pb/Bi = 57, Rb/Tl = 177, Er/Ag = 52, Cu/Au = 3.2×10 4 , Sm/Mo = 7.5, Nd/W = 40, Cl/Li = 10.8, F/Nd = 21.9, and La/B = 1.8. The ( ) value is calculated at ~5. The upper crust composition is less evolved and higher in TiO 2 , total FeO, Co, Cr, Ni, Sc and V, and lower in Na 2 O, K 2 O and Nb, Ta, Rb, Th, U, and Zr, than previous estimates based on shield samplings. Because usually the uppermost layer of the crust, where mafic volcanics tend to concentrate, has been removed from Precambrian shields, and since our study involves Phanerozoic orogenic belts, the results are suggested to be better representative of the upper crust in a general sense. Trace elements associated with mineralization (e.g., B, Cl, Se, As, Bi, Pd, W, Th, Cs, Ta, Tl, Hg, Au, and Pb) show considerable inter-unit variations by a factor of 2-5 in the upper crust. In addition, the North Qinling paleoactive margin is characterized by anomalous enrichment in Th, U, and Pb in particular and has a marked lower value (3.3) compared to the two cratons and the South Qinling paleopassive margin ( = 4.5-6.2). Each tectonic unit has a relatively homogenous middle crust composition which is broadly similar to the composition of the total crust. The lower crust in East China can be divided into two layers both seismically and chemically. The upper lower crust is characterized by Vp = 6.7 km s -1 and an intermediate composition and the lowermost crust by Vp = 7.1 km s -1 and a mafic composition. The bulk lower crust is still intermediate in composition with 58% SiO 2 due to the dominance of the upper lower crust. P-wave velocities of both the lower and total crusts in East China are slower by 0.2-0.4 km s -1 compared to various global estimates. Correspondingly, the total crust shows an more evolved composition and is characterized by a significant negative Eu anomaly (Eu/Eu * = 0.80), low (10.4), and high (3.0) ratios. The obtained SiO 2 is 64% on a volatile-free basis. The near arc magma ratio implies that intraplate crustal growth contributes < 10% of the continental crust. The relative deficits in Eu, Sr, and transition metals (Cr, Ni, Co, V, and Ti) in the derived crustal compositions of East China, along with slower crustal velocity and thin crustal thickness for the Paleozoic to Mesozoic Qinling-Dabie-Sulu orogenic belt, strongly suggest that lower crust delamination of eclogites, as represented by those from the Dabie-Sulu belt, had played an important role in modification of the East China crust during the Phanerozoic era.

Shan, Gao; Luo, Ting-Chuan; Zhang, Ben-Ren; Zhang, Hong-Fei; Han, Yin-Wen; Zhao, Zi-Dan; Hu, Yi-Ken

1998-06-01

161

Polyaniline-carbon nanofiber composite by a chemical grafting approach and its supercapacitor application.  

PubMed

Unlike conventional routes by van der Waals forces, a facile and novel approach using covalent bonding is established in the present work to synthesize polyaniline (PANI)-grafted carbon nanofiber (CNF) composites as promising supercapacitors. For this purpose, toluenediisocyanate was initially functionalized to carboxylated CNF via amidation followed by reaction with excess aniline to form a urea derivative and residual aniline, which was subsequently polymerized and grafted with a urea derivative. Amidation of CNF (TCNF) and, consequently, the grafting of PANI on TCNF were verified by IR, Raman, 1H NMR, X-ray photoelectron, and UV-visible spectroscopic methods, X-ray diffraction, and thermogravimetric analysis. Morphological analysis revealed uniform distribution of PANI on the surface of TCNF, indicating strong interaction between them. Electrochemical tests of the composite containing 6 wt % TCNF demonstrated efficient capacitance of ?557 F g(-1) with a capacity retention of 86% of its initial capacitance even after 2000 charge-discharge cycles at a current density of 0.3 A g(-1), suggesting its superiority compared to the materials formed by van der Waals forces. The remarkably enhanced electrochemical performance showed the importance of the phenyl-substituted amide linkage in the development of a ?-conjugated structure, which facilitated charge transfer and, consequently, made it attractive for efficient supercapacitors. PMID:23911041

Kotal, Moumita; Thakur, Awalendra K; Bhowmick, Anil K

2013-09-11

162

Pneumatic Characterization of Composite Materials  

Microsoft Academic Search

The dimensional change of some composite materials induced by ambient air pressure change was discovered and dubbed pneumatic strain in 2000. This pneumatic behavior closely resembles hygric behavior, and pneumatic strain is proportional to the ambient air pressure change by the coefficients of the pneumatic expansion. A method termed the suspension method was employed in this work to characterize the

Cho-Liang Tsai; Ming-Chang Cheng; Shun-Fa Hwang; Yi-Shiun Tsai

2002-01-01

163

Method of forming a chemical composition  

DOEpatents

A method of forming a chemical composition such as a chemical hydride is described and which includes the steps of selecting a composition having chemical bonds and which is capable of forming a chemical hydride; providing a source of hydrogen; and exposing the selected composition to an amount of ionizing radiation to encourage the changing of the chemical bonds of the selected composition, and chemically reacting the selected composition with the source of hydrogen to facilitate the formation of a chemical hydride.

Bingham, Dennis N. (Idaho Falls, ID); Wilding, Bruce M. (Idaho Falls, ID); Klingler, Kerry M. (Idaho Falls, ID); Zollinger, William T. (Idaho Falls, ID); Wendt, Kraig M. (Idaho Falls, ID)

2007-10-09

164

Synthesis of Polytetrafluoroethylene-like Films by a Novel Plasma Enhanced Chemical Vapor Deposition Employing Solid Material Evaporation Technique  

NASA Astrophysics Data System (ADS)

Polytetrafluoroethylene (PTFE)-like films were formed by electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (ECR-PECVD) employing the solid material evaporation technique where the PTFE was evaporated by a CO2 laser resulting in the production of fluorocarbon species. This system does not employ any perfluorocompound (PFC) feed gases which cause global warming. In this system, it was found that C2F4 and higher species such as CxFy (x? 2) were generated by CO2 laser evaporation. The films were analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared absorption spectroscopy (FT-IR). As a result, the chemical composition of films formed at microwave powers below 0.4 kW indicated a PTFE-like structure with an F/C ratio of 2.0 and a dielectric constant of 2.0. Densities of CFx (x=1--3) radicals and F atoms in the ECR plasma employing the solid material evaporation technique were measured to understand the behavior of these radicals by infrared diode laser absorption spectroscopy (IRLAS) and actinometric optical spectroscopy (AOES), respectively. From these measurements, higher species of C2F4 and CxFy were clarified to be the important precursors of PTFE-like fluorocarbon films.

Fujita, Kazushi; Ito, Masafumi; Hori, Masaru; Goto, Toshio

2003-02-01

165

Chemical constituents and energy content of some latex bearing plants.  

PubMed

The latex bearing plants Plumeria alba, Calotropis procera, Euphorbia nerrifolia, Nerium indicum and Mimusops elengi were evaluated as potential renewable sources of energy and chemicals. Plant parts (leaf, stem, bark) and also whole plants were analyzed for elemental composition, oil, polyphenol, hydrocarbons, crude protein, alpha-cellulose, lignin and ash. The dry biomass yields were between 4.47 and 13.74 kg/plant. The carbon contents in whole plants varied from 38.5% to 44.9%, while hydrogen and nitrogen contents varied from 5.86% to 6.72% and 1.26% to 2.34%, respectively. The bark of the plants contained the highest amount of hydrocarbons (1.78-3.93%) and the leaves contained the lowest amounts (0.26-1.82%). The unsaponifiable materials and fatty acids in the oil fractions of whole plants ranged from 22.8% to 56.4% and 24.7% to 58.7%, respectively. The highest gross heat value was exhibited by C. procera (6145 cal/g) and the lowest by N. indicum (4405 cal/g). Hydrocarbon fractions were characterized by IR and (1)H-NMR and by thermogravimetric analyses. The activation energy (E(a)) in the third stage of decomposition was the greatest in the hydrocarbon fraction obtained from M. elengi (16.40 kJ mol(-1)) and the lowest for C. procera (3.96 kJ mol(-1)). The study indicated that the plant species might be suitable as alternative source of hydrocarbons and other phytochemicals. PMID:14766154

Kalita, D; Saikia, C N

2004-05-01

166

[Study on content variation of chemical constituents during combination of rhizoma coptidis alkaloids with fructus evodiae flavonoids by high performance liquid chromatography].  

PubMed

In order to study the compatibility of Chinese herbal drugs, a method was proposed by investigating chemical reactions with combination of chemical constituents or major groups of chemical compounds of Chinese herbal drugs. The content variation of chemical constituents during combination of rhizoma coptidis alkaloids with fructus evodiae flavonoids was analyzed by high performance liquid chromatography (HPLC). The experimental results showed that only small changes of the relative peak areas of different chemical constituents were observed and no new peaks were detected. No chemical reactions were observed during the compatibility test of rhizoma coptidis alkaloids with fructus evodiae flavonoids. PMID:16830467

Pan, Langsheng; Lü, Xiuyang; Xu, Haidan; Wu, Pingdong

2006-03-01

167

Structure, composition, and chemical reactivity of carbon nanotubes by selective nitrogen doping  

Microsoft Academic Search

Carbon nanotubes (CNTs) doped with a range of nitrogen contents (0–10at.%) were prepared via a floating catalyst CVD method using ferrocene, NH3, and xylene or pyridine. XPS and Raman microscopy were used to assess quantitatively the compositional and structural properties of the nitrogen-doped carbon nanotubes (N-CNTs). XPS analysis indicates a shift in and broadening of the C1s spectra track with

Stephen Maldonado; Stephen Morin; Keith J. Stevenson

2006-01-01

168

Predicting Properties Of Composite Materials  

NASA Technical Reports Server (NTRS)

Micromechanical Combined Stress Analysis (MICSTRAN) computer code provides materials engineers with easy-to-use personal-computer-based software tool to calculate overall properties of composite, given properties of fibers and matrix. Computes overall thermoelastic parameters and stresses by micromechanical analysis. Written in FORTRAN 77.

Naik, Rajiv A.

1994-01-01

169

Processing composite materials  

NASA Technical Reports Server (NTRS)

The fabrication of several composite structural articles including DC-10 upper aft rudders, L-1011 vertical fins and composite biomedical appliances are discussed. Innovative composite processing methods are included.

Baucom, R. M.

1982-01-01

170

CHAPTER XVII CHEMICAL COMPOSITION  

E-print Network

L___________________________________________ 382 Inorganic constltuents____________ __ __ ___ _ __ __ _ 383 Iodine the tissues and organs, exclusive of skeleton or shells, consists of three major groups of organic eompounds is blown through it to remove grit, pieces of broken shell, and mud. The pro- cedure affects the chemical

171

Hierarchical zinc oxide materials with multiple porosity prepared by ultrafast temperature gradient chemical gas-phase synthesis.  

PubMed

The preparation of materials characterized by three types of porosity could be prepared by a continuous chemical gas-phase method. The multistep formation mechanism involves a critical temperature gradient and occurs within seconds. The resulting hollow aerogel materials show superior properties as gas sensors in comparison to materials constructed from compact nanoparticles. PMID:22213088

Dilger, Stefan; Lizandara-Pueyo, Carlos; Krumm, Michael; Polarz, Sebastian

2012-01-24

172

Accelerated Insertion of Materials - Composites.  

National Technical Information Service (NTIS)

The objective of the Accelerated Insertion of Materials - Composites (AIM-C) program is to develop and validate new approaches for materials development that will accelerate the insertion of materials into production hardware.

G. Havskjold

2001-01-01

173

Utilization of composite materials by the US Army: A look ahead  

NASA Technical Reports Server (NTRS)

An overview of the use of composite materials in the Army is given. Important efforts to document design information, supporting research, and some national applications for composite materials are given. The use of Kevlar fiber in both vests and helmets for the soldier is outlined. The advantages of using fiberglass in the hull of the Bradley fighting ground vehicle is given. The full potential of composite materials is realized in the recently awarded LH Comanche RAH-66 program. The use of composites for application to rocket motor uses, wings, fins, and casings is under development. Because of the uncertain funding profile, it is more important than ever that technology planning provide the basis for effective prioritization and leveraging of the tech base efforts involving advanced materials.

Chait, Richard

1992-01-01

174

Alumina fiber/alumina matrix composites prepared by a chemical vapor infiltration technique  

SciTech Connect

Ceramic/ceramic composites made of alumina fibers embedded in an alumina matrix were obtained from fibrous alumina preforms (fiber volume = 0.12 to 0.40) using a chemical vapor infiltration technique based on gaseous alumina precursors (AlCl3-H2-CO2). Low deposition temperatures (950 to 1000 C) and total pressures (2 to 3 kPa) must be used to preferentially deposit alumina within the pores rather than on the external surface of the preform. Different fiber orientations were studied: i.e. randomly oriented short fibers and one- and two-dimensional preforms. Densification was performed down to residual open porosity of the order of 10 to 15 percent. For a one-dimensional alpha-alumina fiber composite (residual porosity about 10 percent), flexural strengths of 250 MPa and about 100 MPa were obtained at room temperature and 1200 C, respectively. Most composites exhibited brittle failure at room temperature. 20 references.

Colmet, R.; Lhermitte-Sebire, I.; Naslain, R.

1986-04-01

175

Chemical composition of human and canine fascia lata.  

PubMed

The fascial system is an integral part of the musculoskeletal system. It is a three-dimensional network of connective tissue spreading ubiquitously throughout the body, surrounding muscles, bones, internal organs, nerves, vessels, and other structures. The basic biophysical properties of the fascial system are determined by its structure and chemical composition. This study aimed to determine the elemental composition of pathologically unchanged fascia lata of the thigh, collected during autopsies on humans and dogs. The wide spectrum of elements analysed included both macro and micro elements. The analyses were conducted using scanning electron microscopy with X-ray microanalysis (SEM-EDS). Concentrations of the following macro and micro elements were determined: C, N, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Fe Co, Ni, Cu, and Zn. The obtained results showed significant differences between human and canine fascia lata regarding the content of most of the examined elements (p < 0.05), except for N. These data may in future provide a starting point for the establishment of reference values for the content of various elements in normal fascial tissue and may also serve to verify the usefulness of experimental animal material as a substitute for human tissue. PMID:23173122

Maksymowicz, Krzysztof; Marycz, Krzysztof; Szotek, Sylwia; Kali?ski, Krzysztof; Serwa, Ewa; ?ukomski, Robert; Czoga?a, Joanna

2012-01-01

176

Notched Strength of Composite Materials  

Microsoft Academic Search

A macroscopic model for predicting the strength of a composite laminate containing a circular notch is introduced. A property, which quantifies the reduction in strength of a given composite material or laminate due to a circular notch, is proposed. The superposition of notched strength data for several important composite material systems and laminate stacking sequences is achieved through development of

R. Byron Pipes; Robert C. Wetherhold; John W. Gillespie

1979-01-01

177

Fundamental procedures for determining ergosterol content of decaying plant material by liquid chromatography.  

PubMed

Portions of published procedures for measurement of ergosterol content of decomposing plants were examined for their influence upon ergosterol yield. Common methods of treatment of plant samples prior to sterol extraction (e.g., oven drying, freezing, lyophilization) led to reduced recoveries of ergosterol (ca. 20 to 80%). The least destructive method was direct placement and storage in methanol. Photoconversion of ergosterol is not likely to cause losses during analysis, but losses are likely if there is insufficient mixing during neutral-lipid partitioning from base-hydrolysis reagents. Homogenization (two times for 2 min) and refluxing (2 h) in methanol were equally effective in extracting ergosterol. Direct extraction in base-hydrolysis reagents was less effective (by ca. 40%). PMID:16347700

Newell, S Y; Arsuffi, T L; Fallon, R D

1988-07-01

178

Method to fabricate layered material compositions  

DOEpatents

A new class of processes suited to the fabrication of layered material compositions is disclosed. Layered material compositions are typically three-dimensional structures which can be decomposed into a stack of structured layers. The best known examples are the photonic lattices. The present invention combines the characteristic features of photolithography and chemical-mechanical polishing to permit the direct and facile fabrication of, e.g., photonic lattices having photonic bandgaps in the 0.1-20.mu. spectral range.

Fleming, James G. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM)

2002-01-01

179

Electromagnetic properties of Permendur granular composite materials containing flaky particles  

NASA Astrophysics Data System (ADS)

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

Kasagi, Teruhiro; Tsutaoka, Takanori; Hatakeyama, Kenichi

2014-10-01

180

Chemical analysis and biological testing of materials from the EDS coal liquefaction process: a status report  

SciTech Connect

Representative process materials were obtained from the EDS pilot plant for chemical and biological analyses. These materials were characterized for biological activity and chemical composition using a microbial mutagenicity assay and chromatographic and mass spectrometric analytical techniques. The two highest boiling distillation cuts, as well as process solvent (PS) obtained from the bottoms recycle mode operation, were tested for initiation of mouse skin tumorigenicity. All three materials were active; the crude 800/sup 0 +/F cut was substantially more potent than the crude bottoms recycle PS or 750 to 800/sup 0/F distillate cut. Results from chemical analyses showed the EDS materials, in general, to be more highly alkylated and have higher hydroaromatic content than analogous SRC II process materials (no in-line process hydrogenation) used for comparison. In the microbial mutagenicity assays the N-PAC fractions showed greater activity than did the aliphatic hydrocarbon, hydroxy-PAH, or PAH fractions, although mutagenicity was detected in certain PAH fractions by a modified version of the standard microbial mutagenicity assay. Mutagenic activities for the EDS materials were lower, overall, than those for the corresponding materials from the SRC II process. The EDS materials produced under different operational modes had distinguishable differences in both their chemical constituency and biological activity. The primary differences between the EDS materials studied here and their SRC II counterparts used for comparison are most likely attributable to the incorporation of catalytic hydrogenation in the EDS process. 27 references, 28 figures, 27 tables.

Later, D.W.; Pelroy, R.A.; Wilson, B.W.

1984-05-01

181

Chemical vapor infiltration of non-oxide ceramic matrix composites  

SciTech Connect

Continuous fiber ceramic composites are enabling new, high temperature structural applications. Chemical vapor infiltration methods for producing these composites are being investigated, with the complexity of filament weaves and deposition chemistry merged with standard heat and mass transport relationships. Silicon carbide- based materials are, by far, the most mature, and are already being used in aerospace applications. This paper addresses the state-of-the-art of the technology and outlines current issues.

Besmann, T.M.; Stinton, D.P.; Lowden, R.A.

1993-12-31

182

Nonlinear Dynamic Properties of Layered Composite Materials  

SciTech Connect

We present an application of the asymptotic homogenization method to study wave propagation in a one-dimensional composite material consisting of a matrix material and coated inclusions. Physical nonlinearity is taken into account by considering the composite's components as a Murnaghan material, structural nonlinearity is caused by the bonding condition between the components.

Andrianov, Igor V.; Topol, Heiko; Weichert, Dieter [Institute of General Mechanics, RWTH Aachen University, Termplergraben 64, Aachen, D-52062 (Germany); Danishevs'kyy, Vladyslav V. [Prydniprovs'ka State Academy of Civil Engineering and Architecture, Dnipropetrovs'k, Chernishevs'kogo 24a, UA-49600 (Ukraine)

2010-09-30

183

Effect of ceramic coating by aerosol deposition on abrasion resistance of a resin composite material.  

PubMed

Aerosol deposition (AD coating) is a novel technique to coat solid substances with a ceramic film. The purpose of the present study was to investigate the effect of AD coating on abrasion resistance of a resin composite material. A 5-microm-thick aluminum oxide layer was created on the polymerized resin composite. The specimen was cyclically abraded using a toothbrush abrasion simulator for 100,000 cycles. Abraded surface was then measured with a profilometer to determine the average roughness (Ra) and maximum roughness (Rmax). It was found that abrasion cycling increased the Ra value of the No-AD-coating group, but decreased the Ra and Rmax values of the AD coating group. Moreover, the AD coating group showed significantly smaller Ra and Rmax values after 100,000 abrasion cycles as compared to the No-coating control group. Microscopic observation supported these findings. In conclusion, the resistance of the resin composite against toothbrush abrasion was improved by AD coating. PMID:17338303

Taira, Yohsuke; Hatono, Hironori; Mizukane, Masahiro; Tokita, Masahiro; Atsuta, Mitsuru

2006-12-01

184

Chemical processing of lunar materials  

NASA Technical Reports Server (NTRS)

The paper highlights recent work on the general problem of processing lunar materials. The discussion covers lunar source materials, refined products, motivations for using lunar materials, and general considerations for a lunar or space processing plant. Attention is given to chemical processing through various techniques, including electrolysis of molten silicates, carbothermic/silicothermic reduction, carbo-chlorination process, NaOH basic-leach process, and HF acid-leach process. Several options for chemical processing of lunar materials are well within the state of the art of applied chemistry and chemical engineering to begin development based on the extensive knowledge of lunar materials.

Criswell, D. R.; Waldron, R. D.

1979-01-01

185

Determination of chemical composition of siderite in concretions by wavelength-dispersive X-ray spectrometry following selective dissolution.  

PubMed

Determination of chemical composition of siderite (Fe, Me)CO(3) (where Me=Mg, Ca, Mn) present in siderite concretion is developed. An accurate and precise determination of Mg, Ca, Mn and Fe in siderite required complete separation of this mineral from other materials, e.g. calcite, quartz. For this purpose, selective dissolution in acetic acid (HAc) was applied. HAc concentration from 0.1 to 1 mol L(-1) and extraction time from 0.5 to 8h were investigated. In each step of investigation of selective dissolution, the X-ray diffraction measurements (XRD) of the residues was performed and also calcium (complexometric titration) and iron (XRF) in solution were determined. HAc of concentration 0.25 mol L(-1) and extraction time of 2h was adopted for siderite separation because in these conditions the siderite was not dissolved and, simultaneously, calcite was completely dissolved. In the next step, the nondissolved sample was digested in hydrochloric acid. The solution of the separated siderite was pipetted onto membrane filter and Mg, Ca, Mn and Fe were determined by wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry. The calibration was performed using 11 certified reference materials of iron ores. Matrix effects were corrected using empirical coefficient model for intermediate-thickness samples. PMID:19064098

Sitko, Rafa?; Zawisza, Beata; Krzykawski, Tomasz; Malicka, Ewa

2009-01-15

186

Composite materials for biomedical applications: a review.  

PubMed

The word "composite" refers to the combination, on a macroscopic scale, of two or more materials, different for composition, morphology and general physical properties. In many cases, and depending on the constituent properties, composites can be designed with a view to produce materials with properties tailored to fulfill specific chemical, physical or mechanical requirements. Therefore over the past 40 years the use of composites has progressively increased, and today composite materials have many different applications, i.e., aeronautic, automotive, naval, and so on. Consequently many composite biomaterials have recently been studied and tested for medical application. Some of them are currently commercialized for their advantages over traditional materials. Most human tissues such as bones, tendons, skin, ligaments, teeth, etc., are composites, made up of single constituents whose amount, distribution, morphology and properties determine the final behavior of the resulting tissue or organ. Man-made composites can, to some extent, be used to make prostheses able to mimic these biological tissues, to match their mechanical behavior and to restore the mechanical functions of the damaged tissue. Different types of composites that are already in use or are being investigated for various biomedical applications are presented in this paper. Specific advantages and critical issues of using composite biomaterials are also described (Journal of Applied Bio-materials & Biomechanics 2003; 1: 3-18). PMID:20803468

Salernitano, E; Migliaresi, C

2003-01-01

187

Pneumatic Behavior of Composite Materials  

Microsoft Academic Search

The dimensional change of some composite materials induced by ambient air pressure change was discovered and dubbed as pneumatic\\u000a strain in 2000. This pneumatic behavior is similar to the hygric behavior. The pneumatic strain is proportional to the ambient\\u000a air pressure change by the coefficients of pneumatic expansion. In this work, a technique termed suspending method was employed\\u000a for characterizing

Cho-Liang Tsai; Yi-Shiun Tsai

188

Quantitative Chemical Mapping of Nanostructured "Onionlike" Poly(methyl methacrylate)/Polystyrene Composite Particles by Soft  

E-print Network

, "onionlike" multilayered poly- (methyl methacrylate)/polystyrene (PMMA/PS) particles by seeded dispersion polymerization (SDP) and solvent- absorbing/releasing methods (SARM).6 These composite particles have potential

Hitchcock, Adam P.

189

Flame-Resistant Composite Materials For Structural Members  

NASA Technical Reports Server (NTRS)

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

Spears, Richard K.

1995-01-01

190

Chemical composition and biotechnological properties of a polysaccharide from the peels and antioxidative content from the pulp of Passiflora liguralis fruits.  

PubMed

A new polysaccharide with a high molecular weight (greater than 1 x 106 Da) was extracted and characterized from the peels of Passiflora liguralis (granadilla) fruits. Chemical composition of the biopolymer, performed by using a high pressure anion exchange-pulsed amperometric detector (HPAE-PAD), showed the presence of six different sugar residues: xylose, glucose, galactose, galactosamine, an unknown component, and fucose in the relative ratio of 1:0.5:0.2:0.06:0.05:trace. The optical rotation of this xyloglucan was [alpha](D)(25) degrees C = -186.42 (concentration of 1.4 mg/mL of H(2)O), and the viscosity was dependent on the concentration and pH, showing a maximum value of 1.4 eta at a concentration of 3% in distilled water and a maximum value of 7.0 eta in citrate buffer solution. Thermogravimetric analysis indicated that this biopolymer was very stable at high temperatures, showing a degradation temperature at 280 degrees C. The characterization of the polysaccharide was also investigated by spectroscopic methods (1H NMR and IR) pointing out the complexity of this biopolymer and the presence of sugar residues in alpha-manno, alpha-gluco-galacto, and beta-gluco-galacto configurations. The formation of a biodegradable film using this novel xyloglucan was reported, and the anticytotoxic activity of the polysaccharide was studied in a brine shrimp bioassay. Considerable antioxidant activity (Trolox equivalent antioxidant capacity (TEAC) value of 0.32 microM/mg fresh product) was noted in the lipophilic extracts of Passiflora liguralis fruits, indicating, in this fruit, an alternative source of bioactive compounds. PMID:17676862

Tommonaro, G; Rodríguez, C S Segura; Santillana, M; Immirzi, B; Prisco, R De; Nicolaus, B; Poli, A

2007-09-01

191

Composite structural materials  

NASA Technical Reports Server (NTRS)

The composite aircraft program component (CAPCOMP) is a graduate level project conducted in parallel with a composite structures program. The composite aircraft program glider (CAPGLIDE) is an undergraduate demonstration project which has as its objectives the design, fabrication, and testing of a foot launched ultralight glider using composite structures. The objective of the computer aided design (COMPAD) portion of the composites project is to provide computer tools for the analysis and design of composite structures. The major thrust of COMPAD is in the finite element area with effort directed at implementing finite element analysis capabilities and developing interactive graphics preprocessing and postprocessing capabilities. The criteria for selecting research projects to be conducted under the innovative and supporting research (INSURE) program are described.

Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

1981-01-01

192

Supplementary Materials Table of Contents  

E-print Network

, as seen by the dark red and green colors. The reason for the difference in performance between 3340 material should be easily removable. Most photoresists are limited to tens of m in thickness. SU8 is a negative photoresist that can be patterned to thicknesses up to 250 m, but it can be difficult to remove

Shapiro, Benjamin

193

Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites  

NASA Astrophysics Data System (ADS)

In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called "interphase" between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC-TiC)n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC-TiC)n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

2013-06-01

194

Composite materials: A compilation  

NASA Technical Reports Server (NTRS)

Design, analysis and fabrication techniques for boron-aluminum composite-structure technology is presented and a new method of joining different laminated composites without mechanical fasteners is proposed. Also discussed is a low-cost procedure for rigidifying expanded honeycomb tubing and piping simulations. A brief note on patent information is added.

1976-01-01

195

Fast Time Response Measurements of Aerosol Composition by Chemical Ionization Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Fast and accurate measurements of atmospheric aerosol composition is an important part of quantifying and understanding atmospheric pollution and its consequences. Such data can be used for studies of regional haze analysis, development of atmospheric models, atmospheric aerosol source apportionment and aerosol and gas interactions. This presentation describes the development of a new technique for the measurement of atmospheric aerosol composition. A negative ion Chemical Ionization Mass Spectrometry (CIMS) method has been used to perform 1 Hz aerosol composition measurements. A heated inlet is used to evaporate ambient aerosol with subsequent detection of the evolved gases. Two reagent ions, bromide and nitrate, have been used to selectively detect acidic components of the aerosols such as sulfate, nitrate, malonate, and oxalate. The CIMS sulfate measurements in ambient air were compared with a Particle into Liquid Sampler (PILS). These tests showed a high degree of correlation between the measurements and strongly suggest that the CIMS can measure sulfate with a high degree of selectivity and sensitivity. Further tests suggest that CIMS method may be able to also perform selective measurements of a few strong organic acids such as oxalic.

Hecobian, A.; Thompson, A.; Tanner, D.; Peltier, R.; Weber, R.; Huey, G.

2005-12-01

196

Inorganic functional materials: optimization of properties by structural and compositional control.  

PubMed

A review is given of the strategies used to dope inorganic solids and the consequences for properties such as ionic and electronic conductivity. Doping mechanisms involve either substitution of foreign ions onto lattice sites, creation of vacancies on either cation or anion sites, or population of normally empty interstitial sites by either anions or cations. Mechanisms for charge compensation associated with aliovalent doping are reviewed and examples are given in the fields of solid state ionics and high-temperature superconductivity. The strategies used for targeting materials with new properties are reviewed, including a surprising number of cases where startling new properties are encountered in well-known materials. Specific examples discussed include MgB2 superconductor, Na beta-alumina sodium ion conductor, Ca12Al14O33 oxide ion conductor, LiCoMnO4 lithium battery cathode, doped Li4SiO4 tunable lithium ion conductor, and La-doped BaTiO3 ferroelectric, which can be either semiconducting or insulating. Examples are also given of a curious observation that extraordinary properties are often encountered in materials that are on the edge of stability, either structurally or compositionally or at the crossover between different property types. PMID:16900482

West, Anthony R

2006-01-01

197

Chemical Composition, Modulatory Bacterial Resistance and Antimicrobial Activity of Essential Oil the Hyptis martiusii Benth by Direct and Gaseous Contact  

PubMed Central

Background: Several studies have shown that species of the genus Hyptis, have promising antimicrobial and antifungal effects. Objectives: Identify of chemical constituents of essential oil from leaves of Hyptis martiusii and evaluate its effect against bacterial strains by direct and gaseous contact. Materials and Methods: Essential oil was extracted from leaves of Hyptis martiusii Benth using hydro-distillation, and its composition was determined using gas chromatography–mass spectrometry (GC-MS). Chemical analysis showed that there was a predominance of sesquiterpenes. The leaf essential oil was screened for its minimal inhibitory concentration and modulatory effect of aminoglycoside by the direct (MIC) and gaseous (MID) micro-dilution assays for various pathogenic microorganisms. The essential oil remarkably inhibited the growth of all of the tested bacteria (MIC < 512 ?g/mL) except S. aureus (SA358) multidrug resistant (MRSA) by direct contact. Results: Twenty-four compounds representing 92.13% of the essential oil of leaves were characterized; ? -3-carene (6.88%), 1, 8-cineole (7.01%), trans-caryophyllene (9.21%), Cariophyllene oxide (7.47%) and bicyclogermacrene (10.61%) were found as the major components. Modulatory aminoglycoside effect, by direct contact, was showed antagonistic relationship with antimicrobial activity. The gaseous component of the oil inhibited the bacterial growth of all of the tested bacteria in 50% and 25% of oil concentration and demonstrated synergistic interactions can be attributed to the constituting the oil compounds. Conclusions: These results show that this oil influences the activity of the antibiotic and may be used as an adjuvant in the antibiotic therapy of respiratory tract bacterial pathogens. PMID:25237640

de Oliveira, Allan Demetrius Leite; Galvao Rodrigue, Fabiola Fernandes; Douglas Melo Coutinho, Henrique; da Costa, Jose Galberto Martins; de Menezes, Irwin Rose Alencar

2014-01-01

198

Leaf Xanthophyll content and composition in sun and shade determined by HPLC  

Microsoft Academic Search

As a part of our investigations to test the hypothesis that zeaxanthin formed by reversible de-epoxidation of violaxanthin serves to dissipate any excessive and potentially harmful excitation energy we determined the influence of light climate on the size of the xanthophyll cycle pool (violaxanthin + antheraxanthin + zeaxanthin) in leaves of a number of species of higher plants. The maximum

Susan S. Thayer; Olle Björkman

1990-01-01

199

Performance, carcass characteristics and chemical composition of beef affected by lupine seed, rapeseed meal and soybean meal.  

PubMed

To test the effects of different protein sources and levels on performance, carcass characteristics and beef chemical composition, concentrates with three protein sources [Lupine seed (L), Rapeseed meal (R) and Soybean meal (S)] and two protein levels ['normal protein' (NP) or 'high protein' (HP)] were fed to 36 Simmental calves. Calves initially weighed 276 +/- 3.9 kg and averaged 6 months of age and were randomly allocated to the six treatments. Maize silage was offered ad libitum and supplemented with increasing amounts of concentrates (wheat, maize grain, protein sources, vitamin-mineral mix). Normal protein and HP diets were formulated to contain 12.4% and 14.0% crude protein (CP) dry matter (DM) respectively. At the end of the fattening period of 278 days, the final live weight averaged 683 +/- 14.7 kg. Neither level of protein nor its interaction with protein sources had any effects on most of the traits studied. Feeding the R diet significantly increased final weight, average daily gain (ADG), DM intake and CP intake in relation to the L diet; no differences were observed between the L and S diets for these measures. No differences were observed between the R and S groups in final weight or ADG, but the calves fed the R diet consumed more DM and CP than the calves fed the S diet. Bulls fed R diet had higher carcass weight and dressing percentage than the L groups, and no significant differences were detected between the S and L groups. Chemical composition of the Musculus longissimus dorsi was not significantly affected by source of protein. Also, the major saturated fatty acid (SFA) (C16:0 and C18:0) did not significantly differ among the three treatments. Samples from R group had significantly higher proportions of C16:1 t9, C18:1 c11, C18:2 c9 t11, C18:3 c9, 12, 15 and SigmaC18:1 t fatty acids in relation to L and S groups. Although polyunsaturated fatty acid/SFA ratio was similar for the three dietary groups, n-6/n-3 ratio and Sigman-3 fatty acids content were significantly greater for bulls fed R diet in relation to those fed L and S diets. PMID:19663972

Sami, A S; Schuster, M; Schwarz, F J

2010-08-01

200

Controlling charge transport in blue organic light-emitting devices by chemical functionalization of host materials  

SciTech Connect

Generation of white light from OLEDs for general lighting applications requires a highly efficient blue component. However, a stable and power efficient blue OLED component with simple device architecture remains a significant challenge partly due to lack of appropriate host materials. Here we report the photophysical and device properties of ambipolar host phosphine oxide based materials. In this work, we studied the effect of the structural modification made to phosphine oxide-based hosts on the charge balance. We observed significant changes in charge transport within the host occurred upon small modifications to their chemical structure. As a result, an alteration of the chemical design of these materials allows for the control of charge balance of the OLED.

Polikarpov, Evgueni; Koech, Phillip K.; Wang, Liang; Swensen, James S.; Cosimbescu, Lelia; Rainbolt, James E.; Von Ruden, Amber L.; Gaspar, Daniel J.; Padmaperuma, Asanga B.

2011-01-18

201

Mechanical Fasteners for Advanced Composite Materials  

NASA Technical Reports Server (NTRS)

Advanced composite materials, which are increasingly being used to build aircraft, have different properties than the metals they replace. Fasteners intended for composite-material joints must be designed and selected to allow for these differences. For example, blind fasteners (one-sided access) used to assemble composite-to-composite joints have been redesigned to expand to larger diameters to resist pull-through and cocking failures. The fastener designs needed for composite materials are reviewed. Topics discussed are: galvanic corrosion, pull-through resistance, fastener rotation, installation damage, fastener galling and conductivity. A blind fastener recently developed by SPS Technologies is described to show how these requirements are incorporated.

Landt, R. C.

1985-01-01

202

Chemical composition, morphology and optical properties of zinc sulfide coatings deposited by low-energy electron beam evaporation  

NASA Astrophysics Data System (ADS)

The research determines the features of formation, morphology, chemical composition and optical properties of the coatings deposited by the method, proposed for the first time, of the exposure of mechanical mixture of zinc and sulfur powders to low-energy electron beam evaporation. The findings show that the deposited coatings are characterized by high chemical and structural homogeneity in thickness. The study considers the influence of substrate temperature and thickness of the deposited layer on the morphology and the width of the formed ZnS thin layers band gap. Also was shown the possibility to form ZnS coatings with this method using the mixture of zinc and copper sulfide powders.

Ragachev, A. V.; Yarmolenko, M. A.; Rogachev, A. A.; Gorbachev, D. L.; Zhou, Bing

2014-06-01

203

Multiscale study of fatigue behaviour of composite materials by ?-rays computed tomography  

Microsoft Academic Search

The study of microstructure and damage mechanism of elastomeric matrix (EMC), wooden plastic (WPC) and also metal matrix (MMC) composites involves a complicated interplay between material properties and service conditions. So, the study of texture deformation and fatigue behaviour of EMC, WPC and MMC specimens is of considerable practical interest. On the other hand, the occurrence of defect in specimens

E. Bayraktar; S. Antolonovich; C. Bathias

2006-01-01

204

An Overview of Recent Development in Composite Catalysts from Porous Materials for Various Reactions and Processes  

PubMed Central

Catalysts are important to the chemical industry and environmental remediation due to their effective conversion of one chemical into another. Among them, composite catalysts have attracted continuous attention during the past decades. Nowadays, composite catalysts are being used more and more to meet the practical catalytic performance requirements in the chemical industry of high activity, high selectivity and good stability. In this paper, we reviewed our recent work on development of composite catalysts, mainly focusing on the composite catalysts obtained from porous materials such as zeolites, mesoporous materials, carbon nanotubes (CNT), etc. Six types of porous composite catalysts are discussed, including amorphous oxide modified zeolite composite catalysts, zeolite composites prepared by co-crystallization or overgrowth, hierarchical porous catalysts, host-guest porous composites, inorganic and organic mesoporous composite catalysts, and polymer/CNT composite catalysts. PMID:20559508

Xie, Zaiku; Liu, Zhicheng; Wang, Yangdong; Yang, Qihua; Xu, Longya; Ding, Weiping

2010-01-01

205

Spectral Analysis by XANES Reveals that GPNMB Influences the Chemical Composition of Intact Melanosomes  

SciTech Connect

GPNMB is a unique melanosomal protein. Unlike many melanosomal proteins, GPNMB has not been associated with any forms of albinism, and it is unclear whether GPNMB has any direct influence on melanosomes. Here, melanosomes from congenic strains of C57BL/6J mice mutant for Gpnmb are compared to strain-matched controls using standard transmission electron microscopy and synchrotron-based X-ray absorption near-edge structure analysis (XANES). Whereas electron microscopy did not detect any ultrastructural changes in melanosomes lacking functional GPNMB, XANES uncovered multiple spectral phenotypes. These results directly demonstrate that GPNMB influences the chemical composition of melanosomes and more broadly illustrate the potential for using genetic approaches in combination with nano-imaging technologies to study organelle biology.

T Haraszti; C Trantow; A Hedberg-Buenz; M Grunze; M Anderson

2011-12-31

206

Health, safety and environmental requirements for composite materials  

NASA Technical Reports Server (NTRS)

The health, safety and environmental requirements for the production of composite materials are discussed. The areas covered include: (1) chemical identification for each chemical; (2) toxicology; (3) industrial hygiene; (4) fire and safety; (5) environmental aspects; and (6) medical concerns.

Hazer, Kathleen A.

1994-01-01

207

Three-dimensional microstructural design of woven fabric composite material by homogenization method  

SciTech Connect

The strength of woven fabric composite materials depends on the microstructural geometry. However, the conventional methods for mechanical analysis, which have been widely used so far, are insufficient because they cannot take into account for the three-dimensional microstructure. In this study, three-dimensional homogenization method is shown to be effective for the evaluations of the material constants, microscopic stresses and the strength. It has been found that the transverse stresses in the direction of lamination play an important role for the fracture of both fiber bundle and resin. Also, the effect of the mismatched lay-up on the strength has been investigated. It has well been predicted that the mismatched lay-up causes the reduction of the strength and the difference of crack initiation in the resin. These simulations give a new concept of the microstructural design of the composite materials.

Takano, Naoki; Zako, Masaru [Osaka Univ., Suita (Japan). Dept. of Welding and Production Engineering

1995-11-01

208

A Study of the Relationship of Chemical Composition and Humidity to Light Scattering by Aerosols  

Microsoft Academic Search

A chemically pure aerosol of defined size distribution exhibits a unique growth pattern due to adsorption of water vapor, and to hygroscopic and\\/or deliquescence effects which are dependent upon relative humidity and which can be followed by measuring light scattering by the aerosol. A number of pure aerosols were produced artificially in the laboratory, subjected to a controlled humidity environment,

R. J. Charlson; N. C. Ahlquist

1972-01-01

209

Improved Silica Aerogel Composite Materials  

NASA Technical Reports Server (NTRS)

A family of aerogel-matrix composite materials having thermal-stability and mechanical- integrity properties better than those of neat aerogels has been developed. Aerogels are known to be excellent thermal- and acoustic-insulation materials because of their molecular-scale porosity, but heretofore, the use of aerogels has been inhibited by two factors: (1) Their brittleness makes processing and handling difficult. (2) They shrink during production and shrink more when heated to high temperatures during use. The shrinkage and the consequent cracking make it difficult to use them to encapsulate objects in thermal-insulation materials. The underlying concept of aerogel-matrix composites is not new; the novelty of the present family of materials lies in formulations and processes that result in superior properties, which include (1) much less shrinkage during a supercritical-drying process employed in producing a typical aerogel, (2) much less shrinkage during exposure to high temperatures, and (3) as a result of the reduction in shrinkage, much less or even no cracking.

Paik, Jong-Ah; Sakamoto, Jeffrey; Jones, Steven

2008-01-01

210

Preparation, chemical composition and storage studies of quamachil (Pithecellobium dulce L.) aril powder.  

PubMed

Quamachil aril powder samples were prepared and evaluated for chemical composition and sensory quality by packing in two packaging systems during storage for six months. The protein contents were 12.4 and 15.0% in white and pink aril powders respectively. The titrable acidity of white and pink aril powders were 2.4 and 4.8% respectively. Ca and Fe contents in white aril powder samples were 60 and 12 mg/100 g where as in pink aril powder 62 and 16 mg/100 g, respectively. The anthocyanin content in pink powder decreased from 50.5 to 11.2 and 14.1 mg/100 g in samples packed in polyethylene (PE) and metalised polyester polyethylene laminated pouches respectively. Total polyphenol amount increased in both the powders irrespective of packaging material. Sorption isotherms indicated that both white and pink aril powders were hygroscopic and equilibrated at low relative humidity of 28 and 32%, respectively. PMID:23572721

Rao, Galla Narsing; Nagender, Allani; Satyanarayana, Akula; Rao, Dubasi Govardhana

2011-02-01

211

Fast Formation of Conductive Material by Simultaneous Chemical Process for Infilling Through-Silicon Via  

NASA Astrophysics Data System (ADS)

It is necessary to develop a fast and inexpensive fabrication process of vertical electric wiring by through-silicon via (TSV) technology for advanced three-dimensional semiconductor devices. In this research, a fast-forming conductive composite was successfully developed by simultaneous deposition of conductive organic polymer (polypyrrole) and metal (silver) from the liquid phase, accelerated by photoirradiation. The growth rate of the composite was 38 nm·s-1, which is more than 10 times higher than that of copper by conventional plating. The electric conductivity of the composite was 2.1×104 ?-1·cm-1, which is on the same level as general metal conductors. In addition, the effects of reaction conditions on the growth rate and the conductivity of the composites were revealed. From these results, the infilling time of the TSV was expected to shorten from the present 2-10 h to 5-10 m.

Kawakita, Jin; Chikyow, Toyohiro

2012-06-01

212

Fabrication of thermochromic composite using monodispersed VO 2 coated SiO 2 nanoparticles prepared by modified chemical solution deposition  

Microsoft Academic Search

Monodispersed thermochromic VO2 particles were fabricated by VO2 coating onto monodispersed SiO2 nanoparticles with the modified chemical solution deposition technique using vanadium isopropoxide solution and monodispersed SiO2 particle suspension solution. The average size of the resultant VO2–SiO2 particle was 57nm and the coating thickness of the VO2 layer was 6nm. A thermochromic composite was fabricated using the VO2–SiO2 particles and

Hisao Suzuki; Kenji Yamaguchi; Hidetoshi Miyazaki

2007-01-01

213

Characterization of nanoporous carbon fibrous materials obtained by chemical activation of plane tree seed under ultrasonic irradiation.  

PubMed

An ultrasonic irradiation was applied for the impregnation by chemical agents in the chemical activation process of new type of active carbon precursor. Plane tree seed, due to the unique fibrous structure and low cost is a promising eco-friendly raw material for the preparation of activated carbon materials. Ultrasonic irradiation was used for the impregnation step allowing the chemical activation by different agents: potassium or sodium hydroxide, hydrogen peroxide and pyrogallol. The porous structures were examined by nitrogen adsorption/desorption isotherms at 77 K and electrochemically by cyclic voltammetry. The textures of these materials were observed by scanning electron microscopy. The application of ultrasonic irradiation in the impregnation step increased surface area of the final material more than two times in comparison to the material which impregnation in the activation process was by conventional stirring. Ultrasonic irradiation enhances the chemical activation process and the activated carbon fibrous materials with nanoporous structure were obtained by impregnation of seeds with alkaline hydroxides. Total surface areas of these samples were 976 m(2) g(-1) and 1130 m(2) g(-1). These fibers have total specific capacitance as high as 125 F g(-1) and 53 F g(-1) which major fraction in both cases originate from internal micropores structure. PMID:24094648

Kaludjerovi?, Branka V; Jovanovi?, Vladislava M; Stevanovi?, Sanja I; Bogdanov, Žarko D

2014-03-01

214

p-Type Bismuth Telluride-Based Composite Thermoelectric Materials Produced by Mechanical Alloying and Hot Extrusion  

NASA Astrophysics Data System (ADS)

We produced six different composites of p-type bismuth antimony telluride alloys and studied their structure and thermoelectric properties. The components of the composites were obtained in powder form by mechanical alloying. Mixed powders of two different compositions were consolidated by hot extrusion to obtain each bulk composite. The minimum grain size of bulk composites as revealed by scanning electron microscopy shows a 50% reduction compared with the conventional (Bi0.2Sb0.8)2Te3. X-ray diffraction (XRD) analysis only shows peak broadening with no clear indication of separate phases, and indicates a systematic decrease of crystallite size in the composite materials. Scattering mechanisms of charge carriers were evaluated by Hall-effect measurements. The thermoelectric properties were investigated via the Harman method from 300 K up to 460 K. The composites show no significant degradation of the power factor and high peak ZT values ranging from 0.86 to 1.04. The thermal conductivity of the composites slightly increases with respect to the conventional alloy. This unexpected behavior can be attributed to two factors: (1) the composites do not yet contain a significant number of grains whose sizes are sufficiently small to increase phonon scattering, and (2) each of the combined components of the composites corresponds to a phase with thermal conductivity higher than the minimum value corresponding to the (Bi0.2Sb0.8)2Te3 alloy.

Keshavarz, M. K.; Vasilevskiy, D.; Masut, R. A.; Turenne, S.

2013-07-01

215

27 CFR 19.308 - Spirits content of chemicals produced.  

...2014-04-01 false Spirits content of chemicals produced. 19.308 Section 19.308...Production of Distilled Spirits Rules for Chemical Byproducts § 19.308 Spirits content of chemicals produced. All chemicals and...

2014-04-01

216

27 CFR 19.308 - Spirits content of chemicals produced.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Spirits content of chemicals produced. 19.308 Section 19.308...Production of Distilled Spirits Rules for Chemical Byproducts § 19.308 Spirits content of chemicals produced. All chemicals and...

2012-04-01

217

27 CFR 19.308 - Spirits content of chemicals produced.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Spirits content of chemicals produced. 19.308 Section 19.308...Production of Distilled Spirits Rules for Chemical Byproducts § 19.308 Spirits content of chemicals produced. All chemicals and...

2013-04-01

218

Wear of hard materials by hard particles  

SciTech Connect

Hard materials, such as WC-Co, boron carbide, titanium diboride and composite carbide made up of Mo2C and WC, have been tested in abrasion and erosion conditions. These hard materials showed negligible wear in abrasion against SiC particles and erosion using Al2O3 particles. The WC-Co materials have the highest wear rate of these hard materials and a very different material removal mechanism. Wear mechanisms for these materials were different for each material with the overall wear rate controlled by binder composition and content and material grain size.

Hawk, Jeffrey A.

2003-10-01

219

Degradation of simazine from aqueous solutions by diatomite-supported nanosized zero-valent iron composite materials.  

PubMed

A novel composite material based on deposition of nanosized zero-valent iron (nZVI) particles on acid-leached diatomite was synthesised for the removal of a chlorinated contaminant in water. The nZVI/diatomite composites were characterised by X-ray diffraction, scanning electron microscopy, elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. Compared with the pure nZVI particles, better dispersion of nZVI particles on the surface or inside the pores of diatom shells was observed. The herbicide simazine was selected as the model chlorinated contaminant and the removal efficiency by nZVI/diatomite composite was compared with that of the pristine nZVI and commercial iron powder. It was found that the diatomite supported nZVI composite material prepared by centrifugation exhibits relatively better efficient activity in decomposition of simazine than commercial Fe, lab synthesised nZVI and composite material prepared via rotary evaporation, and the optimum experimental conditions were obtained based on a series of batch experiments. This study on immobilising nZVI particles onto diatomite opens a new avenue for the practical application of nZVI and the diatomite-supported nanosized zero-valent iron composite materials have potential applications in environmental remediation. PMID:24231330

Sun, Zhiming; Zheng, Shuilin; Ayoko, Godwin A; Frost, Ray L; Xi, Yunfei

2013-12-15

220

[Stability evaluation of chemical compositions of Rhizoma gastrodiae with 60Co-? irradiation by high performance liquid chromatography].  

PubMed

The main chromatographic fingerprint peaks of Rhizoma gastrodiae were established for evaluating the stability of chemical compositions of Rhizoma gastrodiae with 60Co-gamma irradiation to control the dosage of 60Co-gamma irradiation sterilization by high performance liquid chromatography (HPLC). Eight Rhizoma gastrodiae samples were analyzed. The chromatographic fingerprints of Rhizoma gastrodiae were constructed with 14 common fingerprint peaks, and its 10 main peaks were identified using the similarity evaluation system of chromatographic fingerprints of traditional Chinese medicine (version 2004 A) recommended by State Food and Drug Administration of China. The relative standard deviations of the peak areas of the 10 main peaks were used to evaluate the stability of corresponding chemical compositions of Rhizoma gastrodiae with 60Co-gamma irradiation. The results showed that the compositions of 3 of the 10 main peaks were influenced and a good relationship was obtained between the influence and 60Co-gamma irradiation doses for the eight Rhizoma gastrodiae samples. Some chemical components of Rhizoma gastrodiae weren't steady after 60Co-gamma irradiation, so a low dosage should be selected for 60Co-gamma irradiation sterilization. PMID:22500449

Yang, Xiaorong; Huang, Min; Liu, Sujun; Song, Jiuhua

2011-12-01

221

Composite materials and method of making  

DOEpatents

A method for forming improved composite materials using a thermosetting polyester urethane hybrid resin, a closed cavity mold having an internal heat transfer mechanism used in this method, and the composite materials formed by this method having a hybrid of a carbon fiber layer and a fiberglass layer.

Simmons, Kevin L [Kennewick, WA; Wood, Geoffrey M [North Saanich, CA

2011-05-17

222

Chemical composition and tissue energy density of the cuttlefish (Sepia apama) and its assimilation efficiency by Diomedea albatrosses.  

PubMed

The cuttlefish Sepia apama Gray (Mollusca: Cephalopoda) is a seasonally abundant food resource exploited annually by moulting albatrosses throughout winter and early spring in the coastal waters of New South Wales, Australia. To assess its nutritional value as albatross forage, we analysed S. apama for water, lipid protein, ash contents, energy density and amino acid composition. Because albatrosses consistently consume S. apama parts preferentially in the order of head, viscera and mantle, we analysed these sections separately, but did not identify any nutritional basis for this selective feeding behaviour. The gross energy value of S. apama bodies was 20.9 kJ/g dry mass, but their high water content (>83%; cf <70% for fish) results in a relatively low energy density of 3.53 kJ/g. This may contribute to a need to take large meals, which subsequently degrade flight performance. Protein content was typically >75% dry mass, whereas fat content was only about 1%. Albatrosses feed on many species of cephalopods and teleost fish, and we found the amino acid composition of S. apama to be comparable to a range of species within these taxa. We used S. apama exclusively in feeding trials to estimate the energy assimilation efficiency for Diomedea albatrosses. We estimated their nitrogen-corrected apparent energy assimilation efficiency for consuming this prey to be 81.82 ± 0.72% and nitrogen retention as 2.90 ± 0.11 g N kg(-1) d(-1). Although S. apama has a high water content and relatively low energy density, its protein composition is otherwise comparable to other albatross prey species. Consequently, the large size and seasonal abundance of this prey should ensure that albatrosses remain replete and adequately nourished on this forage while undergoing moult. PMID:20640855

Battam, H; Richardson, M; Watson, A W T; Buttemer, W A

2010-11-01

223

Listening to Chemical Materials: Determination of the Photophysical Parameters by Photoacoustic Spectroscopy  

NASA Astrophysics Data System (ADS)

Recently, photoacoustic (PA) spectroscopy has emerged as a valuable tool for the study of various kinds of materials. Herein, we present the results of PA spectral studies of chemical materials. First, the PA study on luminescent materials in condensed states is reported. Combining with the luminescence technique, the energy transfer efficiency and the intrinsic luminescence quantum yield are determined for a europium (III) complex in the glassy state, smectic A phase, and the isotropic liquid. Second, neodymium (III) compounds with l-glycine, l-phenylalanine, and l-tryptophan are synthesized and their PA spectra are reported. The nephelauxetic ratio and Sinha parameter are calculated based on the PA spectra. The environmental effect on the f-f transitions of the neodymium(III) ion is also studied.

Yang, Y. T.; Zhang, S. Y.; Liu, X. J.

2012-11-01

224

Chemical composition of Hanford Tank SY-102  

SciTech Connect

The US Department of Energy established the Tank Waste Remediation System (TWRS) to safely manage and dispose of the radioactive waste, both current and future, stored in double-shell and single-shell tanks at the Hanford sites. One major program element in TWRS is pretreatment which was established to process the waste prior to disposal using the Hanford Waste Vitrification Plant. In support of this program, Los Alamos National Laboratory has developed a conceptual process flow sheet which will remediate the entire contents of a selected double-shelled underground waste tank, including supernatant and sludge, into forms that allow storage and final disposal in a safe, cost-effective and environmentally sound manner. The specific tank selected for remediation is 241-SY-102 located in the 200 West Area. As part of the flow sheet development effort, the composition of the tank was defined and documented. This database was built by examining the history of liquid waste transfers to the tank and by performing careful analysis of all of the analytical data that have been gathered during the tank`s lifetime. In order to more completely understand the variances in analytical results, material and charge balances were done to help define the chemistry of the various components in the tank. This methodology of defining the tank composition and the final results are documented in this report.

Birnbaum, E.; Agnew, S.; Jarvinen, G.; Yarbro, S.

1993-12-01

225

Dual Bioactivities of Essential Oil Extracted from the Leaves of Artemisia argyi as an Antimelanogenic versus Antioxidant Agent and Chemical Composition Analysis by GC/MS  

PubMed Central

The study was aimed at investigating the antimelanogenic and antioxidant properties of essential oil when extracted from the leaves of Artemisia argyi, then analyzing the chemical composition of the essential oil. The inhibitory effect of the essential oil on melanogenesis was evaluated by a mushroom tyrosinase activity assay and B16F10 melanoma cell model. The antioxidant capacity of the essential oil was assayed by spectrophotometric analysis, and the volatile chemical composition of the essential oil was analyzed with gas chromatography-mass spectrometry (GC/MS). The results revealed that the essential oil significantly inhibits mushroom tyrosinase activity (IC50 = 19.16 mg/mL), down-regulates B16F10 intracellular tyrosinase activity and decreases the amount of melanin content in a dose-dependent pattern. Furthermore, the essential oil significantly scavenged 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and 2,2?-azino-bis (3-ethylbenzthiazoline- 6-sulphonic acid) ABTS radicals, showed an apparent reduction power as compared with metal-ion chelating activities. The chemicals constituents in the essential oil are ether (23.66%), alcohols (16.72%), sesquiterpenes (15.21%), esters (11.78%), monoterpenes (11.63%), ketones (6.09%), aromatic compounds (5.01%), and account for a 90.10% analysis of its chemical composition. It is predicted that eucalyptol and the other constituents, except for alcohols, in the essential oil may contribute to its antioxidant activities. The results indicated that essential oil extracted from A. argyi leaves decreased melanin production in B16F10 cells and showed potent antioxidant activity. The essential oil can thereby be applied as an inhibitor of melanogenesis and could also act as a natural antioxidant in skin care products. PMID:23203088

Huang, Huey-Chun; Wang, Hsiao-Fen; Yih, Kuang-Hway; Chang, Long-Zen; Chang, Tsong-Min

2012-01-01

226

Regulation of responsiveness of phosphorescence toward dissolved oxygen concentration by modulating polymer contents in organic-inorganic hybrid materials.  

PubMed

Platinum(II) octaethylporphyrin (PtOEP)-loaded organic-inorganic hybrids were obtained via the microwave-assisted sol-gel condensation with methyltrimethoxysilane and poly(vinylpyrrolidone). From transparent and homogeneous hybrid films, the strong phosphorescence from PtOEP was observed. Next, the resulting hybrids were immersed in the aqueous buffer, and the emission intensity was monitored by changing the dissolved oxygen level in the buffer. When the hybrid with relatively-higher amount of the silica element, the strong phosphorescence was observed even under the aerobic conditions. In contrast, the emission from the hybrids with lower amounts of the silica element was quenched under the hypoxic conditions. This is, to the best of our knowledge, the first example to demonstrate that the responsiveness of the phosphorescence intensity of PtOEP in hybrid films to the dissolved oxygen concentration in water can be modulated by changing the percentage of the contents in the material. PMID:24794749

Okada, Hiroshi; Tanaka, Kazuo; Chujo, Yoshiki

2014-06-15

227

Development of anti-icing materials by chemical tailoring of hydrophobic textured metallic surfaces.  

PubMed

Ice on surfaces can have dramatic consequences for human activities. Over the last decades, the design of new materials with anti-icing properties has generated significant research efforts for the prevention of ice accretion. Here we investigate water freezing temperatures on untreated and negatively charged hydrophobic stainless steel surfaces and use these temperatures to evaluate icephobicity. Supercooled water microdroplets are deposited and undergo a slow controlled cooling until spontaneous freezing occurs. Textured hydrophobic stainless steel surfaces functionalized with anionic polyelectrolytes brushes display unexpectedly lower freezing temperatures, at least 7 °C lower than polished untreated steel. On the basis of the entropy reduction of the crystalline phase near a charged solid surface, we used a modification of the classical heterogeneous nucleation theory to explain the observed freezing temperatures lessening. Our results could help the design of new composite materials that more efficiently prevent ice formation. PMID:23245630

Charpentier, Thibaut V J; Neville, Anne; Millner, Paul; Hewson, Rob W; Morina, Ardian

2013-03-15

228

Enhanced toughness and stable crack propagation in a novel tungsten fibre-reinforced tungsten composite produced by chemical vapour infiltration  

NASA Astrophysics Data System (ADS)

Tungsten is a promising candidate for the plasma-facing components of a future fusion reactor, but its use is strongly restricted by its inherent brittleness. An innovative concept to overcome this problem is tungsten fibre-reinforced tungsten composite. In this paper we present the first mechanical test of such a composite material using a sample containing multiple fibres. The in situ fracture experiment was performed in a scanning electron microscope for close observation of the propagating crack. Stable crack propagation accompanied with rising load bearing capacity is observed. The fracture toughness is estimated using the test results and the surface observation.

Riesch, J.; Höschen, T.; Linsmeier, Ch; Wurster, S.; You, J.-H.

2014-04-01

229

Oxygen and Magnesium Isotopic Compositions of Asteroidal Materials Returned from Itokawa by the Hayabusa Mission  

NASA Technical Reports Server (NTRS)

The Hayabusa spacecraft made two touchdowns on the surface of Asteroid 25143 Itokawa on November 20th and 26th, 2005. The Asteroid 25143 Itokawa is classified as an S-type asteroid and inferred to consist of materials similar to ordinary chondrites or primitive achondrites [1]. Near-infrared spectroscopy by the Hayabusa spacecraft proposed that the surface of this body has an olivine-rich mineral assemblage potentially similar to that of LL5 or LL6 chondrites with different degrees of space weathering [2]. The spacecraft made the reentry into the Earth s atmosphere on June 12th, 2010 and the sample capsule was successfully recovered in Australia on June 13th, 2010. Although the sample collection processes on the Itokawa surface had not been made by the designed operations, more than 1,500 grains were identified as rocky particles in the sample curation facility of JAXA, and most of them were judged to be of extraterrestrial origin, and definitely from Asteroid Itokawa on November 17th, 2010 [3]. Although their sizes are mostly less than 10 microns, some larger grains of about 100 microns or larger were also included. The mineral assembly is olivine, pyroxene, plagioclase, iron sulfide and iron metal. The mean mineral compositions are consistent with the results of near-infrared spectroscopy from Hayabusa spacecraft [2], but the variations suggest that the petrologic type may be smaller than the spectroscopic results. Several tens of grains of relatively large sizes among the 1,500 grains will be selected by the Hayabusa sample curation team for preliminary examination [4]. Each grain will be subjected to one set of preliminary examinations, i.e., micro-tomography, XRD, XRF, TEM, SEM, EPMA and SIMS in this sequence. The preliminary examination will start from the last week of January 2011. Therefore, samples for isotope analyses in this study will start from the last week of February 2011. By the time of the LPSC meeting we will have measured the oxygen and magnesium isotopic composition of several grains. We will present the first results from the isotope analyses that will have been performed.

Yurimoto, H; Abe, M.; Ebihara, M.; Fujimura, A.; Hashizume, K.; Ireland, T. R.; Itoh, S.; Kawaguchi, K.; Kitajima, F.; Mukai, T.; Nagao, K.; Nakamura, T.; Naraoka, H.; Noguchi, T.; Okazaki, R.; Sakamoto, N.; Seto, Y.; Tsuchiyama, A.; Uesugi, M.; Yada, T.; Yoshikawa, M.; Zolensky, M.

2011-01-01

230

Fatigue Crack and Porosity Measurement in Composite Materials by Thermographic and Ultrasonic Methods  

NASA Technical Reports Server (NTRS)

Many nondestructive methods exist for the detection of localized material anomalies in an otherwise good composite structure. The problem arises when the material system as a whole has degraded during service or was improperly manufactured. Porosity and intra-ply microcracking are two such conditions that in unlined composite pressure vessels can be very troublesome to detect and when linked through the thickness can be critical to mission success. These leak paths may lead to loss of pressure/propellant, increased risk of explosion and possible cryo-pumping. Research sought nondestructive methods for quantifying porosity and microcracking in composite tankage. Both thermographic and resonance ultrasound methods have been utilized with artificial neural network and statistical approaches to analyze the data. Resonant ultrasound spectroscopy provides measurements, which are sensitive to fine details in the materials character, such as micro-cracking and porosity. Here, the higher frequency (shorter wavelength) components of the signal train provide more significant interaction with the defects causing the spectral characteristics to shift toward lower amplitudes at the higher frequencies. As the density of the defects increases more interactions occur and more drastic amplitude changes are observed. From a thermal perspective, the higher the defect density the lower the through thickness thermal diffusivity will be. Utilizing a point heat source, and thermographically recording the heat profile with time, diffusivity calculations can be made which in turn can be related to the relative quality of the material. Preliminary experiments to verify the measurable effect on the resonance spectrum of the ultrasonic data to detect microcracking and for porosity detection thermographically are presented. Methods involving supervised and unsupervised artificial neural networks as well as other clustering algorithms are developed for signal identification.

Walker, James L.; Russell, Samuel S.; Suits, Michael W.; Workman, Gary L.; Watson, Jason M.; Thom, Robert (Technical Monitor)

2002-01-01

231

Rheological properties of epoxy composites with different reinforcement contents  

Microsoft Academic Search

Epoxy composite materials (ECMs) and composite protective coatings are important for the improvement and further development\\u000a of many engineering areas. Owing to the combination of components with different physical, chemical, thermal, and mechanical\\u000a properties, ECMs have unique adhesive strength, wear resistance, heat resistance, and corrosion resistance. To obtain ECMs,\\u000a ÉD-20 epoxy resin, polyethylene polyamine as a curing agent, modifiers, and

P. P. Savchuk; A. G. Kostornov

2009-01-01

232

Analysis of degradation processes of carbon\\/carbon composites in a high temperature chemical flame by a spectrovideo camera  

Microsoft Academic Search

The purpose of this study is to develop a measurement technique for in situ monitoring of the degradation processes of thermal-resistance materials, such as C\\/C (carbon\\/carbon) composites, in high temperature fields. Spatially, spectrally and temporally resolved images of emission from diatomic molecules were observed in an acetylene–air flame by a spectrovideo camera, assembled by combining a monochromator and a high

M. Kubota; S. Tsuge; K. Kitagawa; N. Arai; N. Ushigome; Y. Kato

1998-01-01

233

Nanophase and Composite Optical Materials  

NASA Technical Reports Server (NTRS)

This talk will focus on accomplishments, current developments, and future directions of our work on composite optical materials for microgravity science and space exploration. This research spans the order parameter from quasi-fractal structures such as sol-gels and other aggregated or porous media, to statistically random cluster media such as metal colloids, to highly ordered materials such as layered media and photonic bandgap materials. The common focus is on flexible materials that can be used to produce composite or artificial materials with superior optical properties that could not be achieved with homogeneous materials. Applications of this work to NASA exploration goals such as terraforming, biosensors, solar sails, solar cells, and vehicle health monitoring, will be discussed.

2003-01-01

234

Extraction of the volatile oil from Carum carvi of Tunisia and Lithuania by supercritical carbon dioxide: chemical composition and antiulcerogenic activity.  

PubMed

This study investigates whether the essential oil prepared from Carum carvi seeds exhibits antiulcerogenic activity. Its volatile oil was obtained by supercritical fluid extraction (SFE) and by hydrodistillation. The essential oils were analysed by GC-MS to monitor their composition. The chemical analysis revealed that the essential oils extracted under SFE conditions had high carvone and limonene contents. The antiulcerogenic activity was evaluated by the HCl/ethanol method, which causes injury to the gastric mucosa. Three treated groups received the essential oil (100-300 mg/kg). The reference group received omeprazole (30 mg/kg) and the control group received NaCl. After 30 min, all groups were treated with HCl/EtOH for gastric ulcer induction. The results show C. carvi essential oil enhanced a significant inhibition of 47%, 81% and 88%, respectively, for three doses of essential oil used, which was similar to that induced by omeprazole (95%) (p < 0.005). PMID:23495832

Baananou, Sameh; Bagdonaite, Edita; Marongiu, Bruno; Piras, Alessandra; Porcedda, Silvia; Falconieri, Danilo; Boughattas, Naceur

2013-01-01

235

Graphite immobilisation in iron phosphate glass composite materials produced by microwave and conventional sintering routes  

NASA Astrophysics Data System (ADS)

An investigation of microwave and conventional processing of iron phosphate based graphite glass composite materials as potential wasteforms for the immobilisation of irradiated graphite is reported. For the base iron phosphate glass, full reaction of the raw materials and formation of a glass melt occurs with consequent removal of porosity at 8 min microwave processing. When graphite is present, iron phosphate crystalline phases are formed with higher levels of residual porosity than in the sample prepared using conventional sintering under argon. It is found that graphite reacts with the microwave field when in powder form but this reaction is minimised when the graphite is incorporated into a pellet, and that the graphite also impedes sintering of the glass. Mössbauer spectroscopy indicates that reduction of iron also occurs with concomitant graphite oxidation. Conventionally sintered samples had lower porosities than the equivalent microwaved ones.

Mayzan, M. Z. H.; Stennett, M. C.; Hyatt, N. C.; Hand, R. J.

2014-11-01

236

Variations in the chemical composition of cassava ( Manihot esculenta Crantz) leaves and roots as affected by genotypic and environmental variation.  

PubMed

The purpose of this study was to assess the quality of cassava cultivars, in terms of cyanogenic potential and composition of macro- and micronutrients, sampled from different locations in rural Mozambique. Total cyanide concentrations in fresh cassava tissues were measured using portable cyanide testing kits, and elemental nutrients were later analyzed from dried plant tissue. Variation in cyanogenic potential and nutrient composition occurred both among cultivars and across locations. The majority of cultivars contained >100 ppm total cyanide, fresh weight, and are therefore considered to be dangerously poisonous unless adequately processed before consumption. Leaf cyanogenic and nutrient content varied with plant water status, estimated using carbon isotope discrimination (?(13)C). The colonization of roots of all cultivars by arbuscular mycorrhizal fungi was also quantified and found to be high, indicating that mycorrhizas could play a key role in plant nutrient acquisition in these low-input farming systems. PMID:22515684

Burns, Anna Elizabeth; Gleadow, Roslyn Margaret; Zacarias, Anabela M; Cuambe, Constantino Estevão; Miller, Rebecca Elizabeth; Cavagnaro, Timothy Richard

2012-05-16

237

Carbon–Carbon Composite Materials  

Microsoft Academic Search

Data are summarized on the performance characteristics and properties of Russian-produced and foreign carbon–carbon composite materials for various engineering applications. The effect of neutron irradiation on their macroscopic properties and structure is examined. The relationships between the radiation-induced dimensional changes and properties of the composites are established, which can be used in assessing the engineering performance and optimizing the fabrication

Yu. S. Virgil'ev; I. P. Kalyagina

2004-01-01

238

Fracture problems in composite materials  

NASA Technical Reports Server (NTRS)

A series of fracture problems in composite materials are identified, their methods of solution are briefly discussed, and some sample results are presented. The main problem of interest is the determination of the stress state in the neighborhood of localized imperfections such as cracks and inclusions which may exist in the composite. Particular emphasis is placed on the evaluation of quantities such as the stress intensity factors, the power of the stress singularity, and the strain energy release rate, which may be used directly or indirectly in connection with an appropriate fracture criterion for the prediction of fracture initiation and propagation load levels. The topics discussed include a crack in layered composites, a crack terminating at and going through a bi-material interface, a penny-shaped crack in a filament-reinforced elastic matrix, and inclusion problems in bonded materials.

Erdogan, F.

1972-01-01

239

Analytical and numerical study of the densification of carbon\\/carbon composites by a film-boiling chemical vapor infiltration process  

Microsoft Academic Search

The film-boiling chemical vapor infiltration (CVI) process is a fast process developed for composite material fabrication, and especially carbon\\/carbon composites. In order to help define optimal conditions, a local 1D model has been developed to study the densification front which establishes itself during the processing of a carbon\\/carbon fibrous preform. The model features heat conduction, precursor gas diffusion, densification reactions

Nathalie Nadeau; Gérard L. Vignoles; Claude-Michel Brauner

2006-01-01

240

Chemical compatibility of cartridge materials  

NASA Technical Reports Server (NTRS)

The objectives were to determine the chemical compatibility of titanium-zirconium-molybdenum (TZM) with GaAs and CdZnTe, and Inconel with HgCdTe and HgZnTe. At the present time, no other studies regarding the compatibility of these crystal components and their respective cartridge materials have been performed. This study was to identify any possible problems between these materials to insure proper containment of possibly hazardous fumes during crystal growth experiments. In this study, the reaction zone between the materials was studied and the amount of degradation to the system was measured. Detailed results are presented.

Ambrose, Bryan; Wilcox, R. C.; Zee, R. H.

1992-01-01

241

MARCO: MAp Retrieval by COntent  

Microsoft Academic Search

A system named MARCO (denoting MAp Retrieval by COntent) that is used for the acquisition, storage,indexing, and retrieval of map images is presented. The input to MARCO are raster images of separate maplayers and raster images of map composites. A legend-driven map interpretation system converts map layerimages from their physical representation to their logical representation. This logical representation is thenused

Hanan Samet; Aya Soffer

1996-01-01

242

Studies on the effect of the copper and zinc content in a silica by-product material when used in mortar  

SciTech Connect

Mortars were prepared with an industrial incinerator waste material similar to silica fume as an additive to or a partial replacement for cement to investigate whether the copper and zinc contents present in the waste material had an adverse effect on the compressive strength. When used as a cement replacement, high copper contents (0.69, 0.96, 1.38% by weight of pozzolanic material) were detrimental to the early strength development. Lower copper contents (0.24 and 0.48% by weight of pozzolanic material) did not affect the strength development. When used as an additive to cement in mortar, the copper content of the material did not affect the strength development. Higher compressive strength compared to a control resulted when the material was used as a 10, 15, or 20% additive to cement (based on the percent weight of cement). Conclusions regarding the effect of the zinc content could not be drawn due to the significant copper concentration relative to the concentration of zinc in the waste material.

Bradley, M.J.; Wiberley, S.E. (Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Chemistry)

1993-11-01

243

Composite Materials for Wind Power Turbine Blades  

Microsoft Academic Search

Renewable energy resources, of which wind energy is prominent, are part of the solution to the global energy problem. Wind turbine and the rotorblade concepts are reviewed, and loadings by wind and gravity as important factors for the fatigue performance of the materials are considered. Wood and composites are discussed as candidates for rotorblades. The fibers and matrices for composites

Povl Brøndsted; Hans Lilholt; Aage Lystrup

2005-01-01

244

Composite materials inspection. [ultrasonic vibration holographic NDT  

NASA Technical Reports Server (NTRS)

Investigation of the application requirements, advantages, and limitations of nondestructive testing by a technique of ultrasonic-vibration holographic-interferometry readout used in a production control facility for the inspection of a single product such as composite compressor blades. It is shown that, for the detection and characterization of disbonds in composite material structures, this technique may represent the most inclusive test method.

Erf, R. K.

1974-01-01

245

LiMn 2 O 4 and LiCoO 2 composite cathode materials obtained by mechanical activation  

Microsoft Academic Search

New composite cathode materials xLiMn2O4\\/(1 ? x) LiCoO2(x = 0.7, 0.6, 0.5 ? 0.4) were obtained by mechanical activation. According to scanning electron microscopy data, the process\\u000a was accompanied by pronounced dispersion and fine mixing of the initial components. In the course of the preparation and electrochemical\\u000a cycling of the composites, LiMn2O4 and LiCoO2 partially reacted, leading to the replacement

N. V. Kosova; E. T. Devyatkina; V. V. Kaichev

2009-01-01

246

Impact of modifying tea–biscuit composition on phytate levels and iron content and availability  

Microsoft Academic Search

The effect of modifying the standard recipe of wheat flour based tea–biscuit on phytate levels, iron content and in vitro availability was investigated. Standard recipe was enriched by addition of dietary fibers and integral raw materials. The average phytic acid content of investigated biscuits ranged from 0.138 to 1.084g\\/100g dry matter of biscuit, depending on biscuit composition. Phytic acid levels

D. Vitali; I. Vedrina Dragojevi?; B. Šebe?i?; L. Vuji?

2007-01-01

247

Combined studies of chemical composition of urine sediments and kidney stones by means of infrared microspectroscopy  

NASA Astrophysics Data System (ADS)

Results of the structural analysis of urinary sediments by means of infrared spectral microscopy are presented. The results are in good agreement with the results of standard optical microscopy in the case of single-component and crystalline urinary sediments. It is found that for noncrystalline or multicomponent sediments, the suggested spectroscopic method is superior to optical microscopy. The chemical structure of sediments of any molecular origin can be elucidated by this spectroscopic method. The method is sensitive enough to identify solid particles of drugs present in urine. Sulfamethoxazole and traces of other medicines are revealed in this study among the other sediments. We also show that a rather good correlation exists between the type of urinary sediments and the renal stones removed from the same patient. Spectroscopic studies of urinary stones and corresponding sediments from 76 patients suffering from renal stone disease reveal that in 73% of cases such correlation exists. This finding is a strong argument for the use of infrared spectral microscopy to prevent kidney stone disease because stones can be found in an early stage of formation by using the nonintrusive spectroscopic investigation of urinary sediments. Some medical recommendations concerning the overdosing of certain pharmaceuticals can also be derived from the spectroscopic studies of urinary sediments.

Tamošaityt?, Sandra; Hendrixson, Vaiva; Želvys, Ar?nas; Tyla, Ram?nas; Ku?inskien?, Zita A.; Jankevi?ius, Feliksas; Pu?etait?, Milda; Jablonskien?, Valerija; Šablinskas, Valdas

2013-02-01

248

Lunar Skylights and Their Chemical Compositions  

NASA Astrophysics Data System (ADS)

In 2009, the Japanese orbiter, SELenological and Engineering Explorer (SELENE) discovered a skylight on the near side of the moon. Skylights are collapsed ceilings of rilles, thought to be caused by moonquakes, meteoroids, or incomplete formation of these lava tube ceilings. Since then, NASA's Lunar Reconnaissance Orbiter has discovered two more skylights, also located on the near side of the moon. Previous research has shown that the physical characteristics of known rilles, can be used as indicators of the presence of yet undiscovered rille and lava dome locations across the lunar surface. We hypothesize that skylights have a signature chemical composition that is unique, and can be used to predict the location of additional skylights on the surface of the moon. For this study, we compared chemical composition data of the three mare sites containing skylights with the 21 mare sites without skylights. Using the software JMARS for the Moon, we compiled multiple datasets to measure the concentrations of 13 different chemical compounds including calcium, iron oxide, titanium dioxide, and thorium. We then conducted a two-tailed T-test of the data, which generated probability values for the mean differences across all 13 chemical compounds of the maria sites with skylights and the maria sites without skylights. Our results show that there is no statistical difference in chemical composition across all of the maria sites examined. Therefore, we conclude that chemical composition does not predict or indicate potential skylight locations on the moon. Further research on other skylight characteristics, for example depth and surrounding underground lava channels, may shed light on the relationships between mare and skylights locations. Three Skylight Locations Found on Lunar Surface 100m View of Mare Tranquilitatis Skylight

Wong, J.; Torres, J.; FitzHoward, S.; Luu, E.; Hua, J.; Irby, R.

2013-12-01

249

Prediction of Protein Secondary Structure Content by Using the Concept of Chou's Pseudo Amino Acid Composition and Support Vector Machine  

Microsoft Academic Search

Protein secondary structure carries information about local structural arrangements. Significant majority of suc- cessful methods for predicting the secondary structure is based on multiple sequence alignment. However, the multiple alignment fails to achieve accurate results when a protein sequence is characterized by low homology. To this end, we propose a novel method for prediction of secondary structure content through comprehensive

Chao Chen; Lixuan Chen; Xiaoyong Zou; Peixiang Cai

2009-01-01

250

Robotic systems for the determination of the composition of solar system materials by means of fireball spectroscopy  

NASA Astrophysics Data System (ADS)

The operation of the automated CCD spectrographs deployed by the University of Huelva at different observatories along Spain is described. These devices are providing information about the chemical nature of meteoroids ablating in the atmosphere. In this way, relevant physico-chemical data are being obtained from the ground for materials coming from different bodies in the Solar System (mainly asteroids and comets). The spectrographs, which work in a fully autonomous way by means of software developed for this purpose, are being employed to perform a systematic fireball spectroscopic campaign since 2006. Some examples of meteor spectra obtained by these devices are also presented and discussed.

Madiedo, José M.

2014-12-01

251

Determination of the composition of the organic matter chemically stabilized by agricultural soil clay minerals: Spectroscopy and Density Fractionation  

NASA Astrophysics Data System (ADS)

The interactions between soil organic matter and clay minerals are considered important processes because of their ability to sequester C in soil for long periods of time, and hence control C in the global C cycle when present. However, differing results have been reported regarding the composition of the soil organic matter - aromatic fractions versus aliphatic fractions - associated with clay minerals. To clarify this critical issue and better understand the C sequestration process in soils, we aimed to determine the nature of the chemically bound natural organic matter on clay surfaces, and to probe the speciation and spatial distribution of C in the soil clay nanoparticles using direct spectroscopic measurements namely solid-state CP-MAS and DP-MAS 13C NMR spectroscopy, x-ray diffraction spectroscopy (XRD), and scanning transmission x-ray microscopy (STXM). We tested the hypotheses that peptides and polysaccharides are stabilized by the smectite-illite clay while the lipids and black carbon are a separate phase; and that they are evenly distributed on clay surfaces. A soil clay fraction (5.5% organic C) was isolated from the surface of a prairie soil (Mollisol) in southwestern Minnesota, characterized by a pH 6.0, 32.5% clay content, and 3.7% organic carbon, using a sonication-sedimentation-siphoning process in distilled water. Then was subjected to density separation combined with low energy ultrasonic dispersion to separate the free organic and black C (light fraction) from the chemically bound C (heavy fraction). The XRD results indicated a dominance of interstratified smectite-illite clays in soil. The 13C-NMR spectra of the soil clay fraction suggested that polysaccharides and polypeptides are the prevailing components of the organic matter associated with the mineral clay, with only a minor component of aromatic C. The light fraction has strong alkyl C-H bands characteristic of fatty acids plus strong C-O bands characteristic of polysaccharides, including the anomeric C band centered at 105 ppm. The aromatic band at 130 ppm and the phenolic C-O band at 150 pm are strong as well indicating the presence of black carbon and lignin-derived components, contrary to the heavy fraction where they are almost absent. STXM results indicated that the proteins are abundant in the soil clay fraction, separate from lipids, and partially associated with saccharides. The black carbon constitutes a separate phase, but is amply present with lipids and lignin-derived compounds in the light fraction. We conclude that (1) the smectite-illite sheets in our soils preferentially retain peptides, and polysaccharides favoring the protection of these normally readily biodegradable fractions relative to the lignin-derived phenolic components; (2) the black carbon constitutes a major component of the light fraction, and is partially attached to the organic matter bonded with the smectitic clays; and (3) the lipids are associated with soil clay fraction as a separate phase, but are not bound to clay minerals.

Oufqir, Sofia; Bloom, Paul; Toner, Brandy; Hatcher, Patrick

2014-05-01

252

Acoustic emission monitoring of polymer composite materials  

NASA Technical Reports Server (NTRS)

The techniques of acoustic emission monitoring of polymer composite materials is described. It is highly sensitive, quasi-nondestructive testing method that indicates the origin and behavior of flaws in such materials when submitted to different load exposures. With the use of sophisticated signal analysis methods it is possible the distinguish between different types of failure mechanisms, such as fiber fracture delamination or fiber pull-out. Imperfections can be detected while monitoring complex composite structures by acoustic emission measurements.

Bardenheier, R.

1981-01-01

253

Method of making a composite refractory material  

DOEpatents

A composite refractory material is prepared by combining boron carbide with furan resin to form a mixture containing about 8 wt. % furan resin. The mixture is formed into a pellet which is placed into a grit pack comprising an oxide of an element such as yttrium to form a sinterable body. The sinterable body is sintered under vacuum with microwave energy at a temperature no greater than 2000.degree. C. to form a composite refractory material.

Morrow, Marvin S. (Kingston, TN); Holcombe, Cressie E. (Knoxville, TN)

1995-01-01

254

Chemical Composition of Aerosol Particles Emitted by a Passenger Car Engine Fueled by Ethanol/Gasoline Mixtures  

NASA Astrophysics Data System (ADS)

With concerns of national security, climate change, and human health, many people have called for oil independence for the United States and for the creation of alternative fuels. Ethanol has been widely praised as a viable alternative to petroleum-based fuels, due to the fact that it can be produced locally. A great deal of work has been done to characterize the energy balance of ethanol production versus consumption, but there have been fewer studies of the environmental and health impacts of emissions from combustion of ethanol/gasoline mixtures such as those burned in the modern vehicle fleet. To study the particulate emissions from such fuels, different ethanol/gasoline fuel mixtures with 0, 20, 40, and 85% ethanol were burned in a dynamometer-mounted automobile engine. The engine exhaust was diluted and sampled with two aerosol Time-of-Flight Mass Spectrometers (TSI 3800 ATOFMS), sampling different particle size ranges (50-500 nm and 150-3000 nm, respectively), to measure size and composition of the emitted aerosol particles. A variety of other aerosol characterization techniques were also employed to determine the size distribution of the aerosol particles, the mass emission rate from the engine, and the concentration of polycyclic aromatic hydrocarbons (PAHs) and elemental carbon (EC) in the particle emissions. Here we will focus on results from the ATOFMS, which provides us with a particle size and mass spectra - for both negative and positive ions - for each particle that is sampled. Particles being emitted were found to contain primarily PAHs, elemental carbon (EC), nitrates, and sulfates. Particles were analyzed to investigate trends in particle composition as a function of fuel ethanol content, particle size, and for the types of particles emitted. A trend in particle type as a function of fuel ethanol content was evident in smaller particles, and trends in composition as a function of particle size were visible across the entire size range sampled.

Medrano, J. M.; Gross, D. S.; Dutcher, D. D.; Drayton, M.; Kittelson, D.; McMurry, P.

2007-12-01

255

Evaluation of momentum effects on material properties of titanium-silicon-nitrogen nanocrystalline composites prepared by pulsed dc reactive sputtering  

NASA Astrophysics Data System (ADS)

The investigation had as a general goal the deposition of thin films that possess high erosion wear resistance. The fabrication technique used for this purpose was an industry-compatible process called reactive sputtering physical vapor deposition (PVD). The study specifically involved depositing Ti-Si-N nc-composite thin films according to generic design principles that specify using a transition metal nitride and a covalent nitride material system in order to produce hard coatings (˜50 GPa Vickers hardness). Thin films were deposited using reactive pulsed, do sputtering to avoid arcing issues and for wider control over the process properties such as the deposition rate and level of bombardment. Two sputter guns used synchronized pulsed do signals, which were asymmetric and bipolar with positive voltages of less than +100 V and negative voltages of -500 to -1000 V. The pulsing frequency was varied in this co-deposition system as a possible means to control the nanocrystalline composite thin film properties by controlling the level of bombardment. The thin films were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM) to determine the crystallinity of the films. XRD results show the presence of the (111), (220), and (200) orientations with the later being most common. TEM bright-field images show nanocrystals in the 10 to 40 nm range, depending on the pulsing frequency. A columnar morphology (50--120 nm diameters) was observed in the nc-composite films from images taken with a scanning electron microscope. Verification of the TiN and SiN phases was accomplished using XPS to analyze the binding energies of Ti 2p and Si 2p electrons, respectively. Oxygen was detected in the films, (2--9 at.%) depending on pulsing frequency, and it severely worsened the mechanical properties, specifically the hardness, by reacting with some of the silicon in the SiN phase. A maximum Vickers hardness, Hv, of 32 GPa and reduced elastic modulus, Er, of 290 GPa were measured using displacement controlled nanoindentation. Normalized nanoindentation depths of 5, 10 and 15% of the film thickness were performed and showed that normalized indent depths of 10% produced reliable data. Analysis of the plasma properties in situ shows variation in the ionized species, their density, and energy as a function of pulsing frequency. A Langmuir probe and energy-resolved mass spectrometer (Hiden probe) were used to analyze the conditions at the substrate position within the deposition chamber. The major ion constituent in the plasma was N2 + with N+, Ti+, SiN+, and TiN+ comprising the remaining species. The energy analysis of N2+ and N+ show that the energy distribution is bimodal with the majority of ions < 5 eV, while a secondary, less intense peak of 70 to 75 eV exists. This information was used to calculate a universally applicable momentum-per-atom figure of merit at the growing film surface during deposition. The nc-composites deposited at 10 mT N2 show that as the momentum-per-atom increases, so do the Hv and Er. The nc-composites deposited at 5 mT N2 show a negative correlation to the content of (111) orientation in the films, which itself correlates to the momentum-per-atom.

Sunal, Paul Dennis

256

Changes in chemical composition in male turkeys during growth.  

PubMed

In growing animals, requirements for many nutrients (and energy) are determined by the retention of these nutrients. During growth, this retention changes in an absolute way and also between nutrients and energy, resulting in changing nutrient requirements. The objective of this study was to describe the changes in chemical composition in male growing turkeys. The serial slaughter technique was used to determine the composition of amino acids, lipid, ash, and water in feather-free body (FFB) and feathers in male turkeys offered feed ad libitum from 1 to 15 wk of age. Allometric relations were used to describe changes in body composition. The feather content in the body decreased from 6% at 1 wk of age to less than 3% at 15 wk of age. The water and protein content in FFB decreased with increasing FFB mass, with allometric scalars (b) of, respectively, 0.967 and 0.970, whereas the lipid content increased with increasing FFB mass (b = 1.388). The water, protein, and ash content in fat-free FFB was constant and represented, respectively, 71.6, 24.2, and 4.2% of the fat-free FFB mass. The amino acid content of FFB protein was relatively constant and only the Cys content decreased between 1 and 15 wk of age, whereas the Ile content increased. Feathers were mostly composed of protein, and the protein content did not change during growth. During growth, the Lys, Met, Trp, His, Tyr, Asp, and Glu contents in feather protein decreased, whereas the Cys, Val, and Ser contents increased. The contribution of feathers to whole-body amino acid retention ranged from 5% for His to 33% for Cys. On average, the weight gain of FFB contained 21.3% protein and 12.7% lipid, corresponding to an energy content of 10.1 kJ/g. The weight gain of feathers contained 87.4% protein, corresponding to an energy content of 20.4 kJ/g. The results of the present study can be used in a factorial approach to determine nutrient requirements in growing turkeys. PMID:21177445

Rivera-Torres, V; Noblet, J; van Milgen, J

2011-01-01

257

Content, format, gender and grade level differences in elementary students' ability to read science materials as measured by the cloze procedure  

NASA Astrophysics Data System (ADS)

Present instructional trends in science indicate a need to reexamine a traditional concern in science education: the readability of science textbooks. An area of reading research not well documented is the effect of color, visuals, and page layout on readability of science materials. Using the cloze readability method, the present study explored the relationships between page format, grade level, sex, content, and elementary school students ability to read science material. Significant relationships were found between cloze scores and both grade level and content, and there was a significant interaction effect between grade and sex in favor of older males. No significant relationships could be attributed to page format and sex. In the area of science content, biological materials were most difficult in terms of readability followed by earth science and physical science. Grade level data indicated that grade five materials were more difficult for that level than either grade four or grade six materials were for students at each respective level. In eight of nine cases, the science text materials would be classified at or near the frustration level of readability. The implications for textbook writers and publishers are that science reading materials need to be produced with greater attention to readability and known design principles regarding visual supplements. The implication for teachers is that students need direct instruction in using visual materials to increase their learning from text material. Present visual materials appear to neither help nor hinder the student to gain information from text material.

Williams, Richard L.; Yore, Larry D.

258

The study of chemical composition and elemental mappings of colored overglaze porcelain fired in Qing Dynasty by micro-X-ray fluorescence  

Microsoft Academic Search

It is very difficult to measure the chemical composition of colored pigments of over-glaze porcelain by X-ray fluorescence because it contains high concentration of Pb. One of the disadvantages of our polycapillary optics is that it has low transmission efficiency to the high energy X-ray. However, it is beneficial to measure the chemical compositions of rich Pb sample. In this

Cheng Lin; Li Meitian; Kim Youshi; Fan Changsheng; Wang Shanghai; Pan Qiuli; Liu Zhiguo; Li Rongwu

2011-01-01

259

Temperature and chemical composition of droplets by optical measurement techniques: a state-of-the-art review  

NASA Astrophysics Data System (ADS)

The measurement of the sizes and the velocities of droplets relies upon widespread and well-established techniques, but characterizing their temperature and their composition remains challenging. The lack of standard methods is particularly detrimental, given the importance of these parameters for validating models and numerical simulations of many spray processes. Heat and mass transfers are dominant aspects in applications such as spray combustion in IC engines, spray cooling, spray drying, wet scrubbers in which liquid sprays capture gas pollutants and also the preparation of nanoparticles via spray route. This paper provides a review of the main techniques available to optically measure the temperature and chemical compositions of single droplets and sprays. Most of these techniques are based on phenomena related to light interaction with matter. Photoluminescence processes like fluorescence and phosphorescence have temperature and composition dependences which can be exploited, while other methods rely on light scattering by the droplets. In particular, the angular position of the rainbow is very sensitive to the refractive index and then to both the temperature and composition. Less widely used diagnostic methods include Raman scattering, thermochromic liquid crystals, thermographic phosphors, infrared thermography, morphology-dependent resonances and their subsequent effects on the stimulated emission of dye molecules. In this review, the emphasis is mainly placed on two groups of techniques—methods based on laser-induced fluorescence and those based on light scattering—but details about alternative methods will be also provided. The potential of combining fluorescence-based techniques or rainbow refractometry with a droplet sizing measurement technique to derive temperature and composition per size class will be also discussed.

Lemoine, Fabrice; Castanet, Guillaume

2013-07-01

260

Visualizing excipient composition and homogeneity of Compound Liquorice Tablets by near-infrared chemical imaging  

NASA Astrophysics Data System (ADS)

This study demonstrated that near-infrared chemical imaging (NIR-CI) was a promising technology for visualizing the spatial distribution and homogeneity of Compound Liquorice Tablets. The starch distribution (indirectly, plant extraction) could be spatially determined using basic analysis of correlation between analytes (BACRA) method. The correlation coefficients between starch spectrum and spectrum of each sample were greater than 0.95. Depending on the accurate determination of starch distribution, a method to determine homogeneous distribution was proposed by histogram graph. The result demonstrated that starch distribution in sample 3 was relatively heterogeneous according to four statistical parameters. Furthermore, the agglomerates domain in each tablet was detected using score image layers of principal component analysis (PCA) method. Finally, a novel method named Standard Deviation of Macropixel Texture (SDMT) was introduced to detect agglomerates and heterogeneity based on binary image. Every binary image was divided into different sizes length of macropixel and the number of zero values in each macropixel was counted to calculate standard deviation. Additionally, a curve fitting graph was plotted on the relationship between standard deviation and the size length of macropixel. The result demonstrated the inter-tablet heterogeneity of both starch and total compounds distribution, simultaneously, the similarity of starch distribution and the inconsistency of total compounds distribution among intra-tablet were signified according to the value of slope and intercept parameters in the curve.

Wu, Zhisheng; Tao, Ou; Cheng, Wei; Yu, Lu; Shi, Xinyuan; Qiao, Yanjiang

2012-02-01

261

Chemical imaging of biological materials by NanoSIMS using isotopic and elemental labels  

SciTech Connect

The NanoSIMS 50 combines unprecedented spatial resolution (as good as 50 nm) with ultra-high sensitivity (minimum detection limit of {approx}200 atoms). The NanoSIMS 50 incorporates an array of detectors, enabling simultaneous collection of 5 species originating from the same sputtered volume of a sample. The primary ion beam (Cs{sup +} or O{sup -}) can be scanned across the sample to produce quantitative secondary ion images. This capability for multiple isotope imaging with high spatial resolution provides a novel new approach to the study of biological materials. Studies can be made of sub-regions of tissues, mammalian cells, and bacteria. Major, minor and trace element distributions can be mapped on a submicron scale, growth and metabolism can be tracked using stable isotope labels, and biogenic origin can be determined based on composition. We have applied this technique extensively to mammalian and prokaryotic cells and bacterial spores. The NanoSIMS technology enables the researcher to interrogate the fate of molecules of interest within cells and organs through elemental and isotopic labeling. Biological applications at LLNL will be discussed.

Weber, P K; Fallon, S J; Pett-Ridge, J; Ghosal, S; Hutcheon, I D

2006-04-10

262

Chemical Composition and Heterogeneity of Wild 2 Cometary Particles Determined by Synchrotron X-ray Fluorescence  

SciTech Connect

Seven cometary dust particle tracks in Stardust aerogel were studied using synchrotron X-ray fluorescence methods at the National Synchrotron Light Source (NY) and Advanced Photon Source (IL). Elemental maps were produced for each of the tracks and elemental abundances for 156 individual fragments within these tracks were determined. Whole-track elemental abundances were inferred by summing the elemental masses for the fragments in each track and scaling by the ratio of total Fe in the map and total Fe in the fragments. In general, whole-track and terminal-particle abundances are dissimilar. The total Fe masses ranged from 4 to 2200 pg, corresponding to impactors in the size range of 2.7 to 22 {mu}m if Fe abundances are equal to the chondritic value. Systematic variations in element abundance with fragment distance from the aerogel entry point were generally subtle but were pronounced in one track (C2115,19). In this track, Zn/Fe was about three orders of magnitude higher at the top, Cr/Fe was two orders of magnitude higher at the bottom, and S was relatively uniform. Compositional convergence data showed that typically analysis of {approx}10 fragments was needed to reach convergent whole-track abundance. Zinc was an exception, showing nonconvergent profiles and steps due to the presence of rare, high-Zn fragments. The resulting wholetrack elemental abundances show diverse patterns that are generally chondritic (i.e., within a factor of three of CI abundances) with some exceptions, notably depletions in S and enrichments in the moderately volatile elements Cu, Zn, and Ga. Enrichments in large ion lithophile elements relative to Fe were observed in one track. Correlation matrices showed several strong elemental correlations, notably selenium associated with sulfur (sulfides), a ubiquitous correlation of the first-row transition metals Cr, Mn, and Fe attributed to the presence of pyroxene, and enrichments of gallium associated with calcium, likely affiliated with Mg-Al glass.

Lanzirotti,A.; Sutton, S.; Flynn, G.; Newville, M.; Rao, W.

2008-01-01

263

Unusual chemical compositions of noctilucent-cloud particle nuclei  

NASA Technical Reports Server (NTRS)

Two sounding rocket payloads were launched from the ESRO range in Sweden during a noctilucent cloud display. Large numbers of submicron particles were collected, most of which appear to be made up of a high density material coated with a low density material. Typical electron micrographs are shown. Particle chemical compositions have been measured by use of dispersive X-ray analysis equipment attached to an electron microscope and have revealed that most of the high density particle nuclei have atomic weights greater than iron.

Hemenway, C. L.

1973-01-01

264

Structural characterization of hard materials by transmission electron microscopy (TEM): Diamond-Silicon Carbide composites and Yttria-stabilized Zirconia  

Microsoft Academic Search

Diamond-Silicon Carbide (SiC) composites are excellent heat spreaders for high performance microprocessors, owing to the unparalleled thermal conductivity of the former component. Such a combination is obtained by the infiltration of liquid silicon in a synthetic diamond compact, where a rigid SiC matrix forms by the reaction between the raw materials. As well as the outstanding thermal properties, this engineered

Joon Seok Park

2008-01-01

265

Chemical Composition of Soils of Northwest and West Central Texas.  

E-print Network

.......................................................................................................... I BULLETIN No. 443 MARCH, 1932 et a Rc the : ture 0 CHEMICAL COMPOSITION OF SOILS OF NORTHWEST AND WEST CENTRAL TEXAS G. S. FRAPS The diatelj squarc w This Bulletin deals with the chemical composition and fertility of samples of typical... with the chemical composition of typical Texas soils. Detailed reports of the surveys with maps of the areas showing the location of the soil types have been published by the Bureau of Chemistry and Soils, United States Department of Agriculture. Description...

Fraps, G. S. (George Stronach)

1932-01-01

266

Changes in the chemical composition of basil caused by different drying procedures.  

PubMed

Basil (Ocimum basilicum L.) leaves were dried using a microwave oven at atmospheric pressure or two traditional methods: air-drying at 50 degrees C and freeze-drying. The microwave-drying was carried out at different powers and times on raw basil leaves, while for air and freeze-drying techniques, both raw and blanched leaves were used. The raw and dried basil was analyzed for selected aroma compounds by gas chromatography/mass spectrometry-selected-ion-monitoring, the chlorophyll a and b by HPLC and the color by a reflected-light colorimeter. For dried samples microwaved for 1 min at 270, 2 min at 440, 1 min at 650, and 1 min at 1100 W, the percentage retentions of the characteristic volatile compounds (eucalyptol, linalool, eugenol, and methyl eugenol) were higher than in the samples dried by traditional methods, with the exception of freeze-dried unblenched basil. Microwave drying allowed a larger retention of chlorophyll pigments than air-drying and freeze-drying (with or without blanching) and preserved the color of the raw basil. Microwave drying requires a much shorter treatment and implied the simultaneous blanching of the material. PMID:12769527

Di Cesare, Luigi Francesco; Forni, Elisabetta; Viscardi, Daniela; Nani, Renato Carlo

2003-06-01

267

Colorimetric evaluation of composite materials with different thickness by reflectance spectroscopy  

NASA Astrophysics Data System (ADS)

Selection of the proper shade and color matching of restorations to natural dentition continues to be one of the most frustrating problems in dentistry and currently available shade guide presents a limited selection of colors compared to those found in natural dentition. This investigation evaluation if the composites resins shade B2 are equivalent to the Vita shade guide B2. Twelve composite resins (Renamel Microfill Super Brite- Cosmedent USA, Renamel Universal Brite- Cosmedent USA, Renamel Microfill Body- Cosmedent USA, Renamel Universal Body- Cosmedent USA, Opallis EB2-FGM, Opallis DB2-FGM, Filtek Supreme XT-3M/ESPE, Filtek Z250-3M/ESPE, Filtek Z350-3M/ESPE, Z100-3M/ESPE, 4 Seasons Dentin-Ivoclar/Vivadent, Tetric Ceram-Ivoclar/Vivadent) shade B2 were used. From each composite, two specimens were made in a steel matrix with 8.0 mm diameter and 10.0 mm different predetermined thickness (0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 mm). The specimens were 40 seconds light polymerized by LED Ultrablue (DMC). The specimens were measured 10 times each to determine the shade using a reflectance spectrophotometer (Pocket Spec). According to results was verified that not any of composites resins shade B2 evaluated in this study presented values of color difference (?E) equivalent to the Vita shade guide B2 and the 2 mm thickness showed the closer match to the Vita shade guide B2.

Portero, Priscila Paiva; Florez, Fernando; Bagnato, Vanderlei; de Oliveira, Osmir Batista, Jr.; de Castro Monteiro Loffredo, Leonor

2007-02-01

268

Chemical composition and nutritional quality of soybean meals prepared by extruder/expeller processing for use in poultry diets.  

PubMed

This research examined variation in chemical composition and nutrient quality of soybeans (SBs) and soybean meals (SBMs) produced at seven commercial extruder/expeller plants in the United States (experiment 1), as well as differences in amino acid digestibilities when roosters were fed SBMs extruded at 121, 135, 150, or 160 degrees C at a U.S. pilot processing plant (experiment 2). In experiment 1, limited variation existed in the composition of SBs arriving at the plants, whereas substantial differences were noted in amino acid composition and protein quality of the resultant SBMs. In experiment 2, the SBMs extruded at 121 and 135 degrees C were underprocessed as noted by high urease activities and lower amino acid digestibilities. Soybean meals extruded at 150 and 160 degrees C resulted in higher amino acid digestibilities and lower urease activities, indicating adequate processing. Large variation exists in the nutritional quality of extruder/expeller SBMs currently in the marketplace. Optimal processing temperatures should be >135 degrees C, and temperatures as high as 165 degrees C do not result in overprocessing. PMID:17032017

Karr-Lilienthal, Lisa K; Bauer, Laura L; Utterback, Pam L; Zinn, Krista E; Frazier, Rodney L; Parsons, Carl M; Fahey, George C

2006-10-18

269

Bacterial Community Composition in the Gut Content and Ambient Sediment of Sea Cucumber Apostichopus japonicus Revealed by 16S rRNA Gene Pyrosequencing  

PubMed Central

The composition of the bacterial communities in the contents of the foregut and hindgut of the sea cucumber Apostichopus japonicus and in the ambient surface sediment was surveyed by 16S rRNA gene 454-pyrosequencing. A total of 188,623 optimized reads and 15,527 operational taxonomic units (OTUs) were obtained from the ten gut contents samples and four surface sediment samples. The sequences in the sediments, foregut contents, and hindgut contents were assigned to 38.0±4.7, 31.2±6.2 and 27.8±6.5 phyla, respectively. The bacterial richness and Shannon diversity index were both higher in the ambient sediments than in the gut contents. Proteobacteria was the predominant phylum in both the gut contents and sediment samples. The predominant classes in the foregut, hindgut, and ambient sediment were Holophagae and Gammaproteobacteria, Deltaproteobacteria and Gammaproteobacteria, and Gammaproteobacteria and Deltaproteobacteria, respectively. The potential probiotics, including sequences related to Bacillus, lactic acid bacteria (Lactobacillus, Lactococcus, and Streptococcus) and Pseudomonas were detected in the gut of A. japonicus. Principle component analysis and heatmap figure showed that the foregut, hindgut, and ambient sediment respectively harbored different characteristic bacterial communities. Selective feeding of A. japonicus may be the primary source of the different bacterial communities between the foregut contents and ambient sediments. PMID:24967593

Gao, Fei; Li, Fenghui; Tan, Jie; Yan, Jingping; Sun, Huiling

2014-01-01

270

The Effect of Chemical Functionalization on Mechanical Properties of Nanotube/Polymer Composites  

NASA Technical Reports Server (NTRS)

The effects of the chemical functionalization of a carbon nanotube embedded in a nanotube/polyethylene composite on the bulk elastic properties are presented. Constitutive equations are established for both functionalized and non-functionalized nanotube composites systems by using an equivalent-continuum modeling technique. The elastic properties of both composites systems are predicted for various nanotube lengths, volume fractions, and orientations. The results indicate that for the specific composite material considered in this study, most of the elastic stiffness constants of the functionalized composite are either less than or equal to those of the non-functionalized composite.

Odegard, G. M.; Frankland, S. J. V.; Gates, T. S.

2003-01-01

271

Chemical composition and vasorelaxant effect induced by the essential oil of Lippia alba (Mill.) N.E. Brown. (Verbenaceae) in rat mesenteric artery  

PubMed Central

Objectives: To investigate the chemical composition and vasorelaxant effect of the essential oil of Lippia alba (EOLA) in rat mesenteric artery. Material and Methods: Chemical composition of EOLA was investigated by gas chromatography-mass spectrometry (GC/MS). Vasorelaxant effect was evaluated in vitro in rat superior mesenteric artery rings. Results: GC/MS analysis revealed the presence of 19 compounds, with geranial (48.58%) and neral (35.42%) being the major constituents. In intact rings precontracted with phenylephrine (Phe: 1 ?M), EOLA (100-1000 ?g/mL) induced relaxation, where the maximal effect (Emax) was 110.8 ± 10.8%. This effect was not modified after endothelium removal (Emax = 134.8 ± 16.5%), after tetraethylammonium (TEA) (Emax = 117.2 ± 4.96%), or in rings precontracted with KCl (80 mM) (Emax = 112.6 ± 6.70%). In addition, EOLA was able to inhibit the contraction caused by CaCl2 and produced a small but significant (P<0.05) additional effect (from 70.5 ± 3.4 to 105.3 ± 13.5%, n = 5) on the maximal relaxation of nifedipine (NIF: 10 ?M). Conclusions: The results demonstrated that EOLA induces endothelium-independent vasorelaxation, which appears to be caused, at least in part, by blocking Ca2+ influx through voltage-operated Ca2+ channels. PMID:22144776

Maynard, Luana G.; Santos, Kátia C.; Cunha, Patrícia S.; Barreto, André S.; Peixoto, Magna G.; Arrigoni-Blank, Fátima; Blank, Arie F.; Alves, Péricles B.; Bonjardin, Leonardo R.; Santos, Márcio R.V.

2011-01-01

272

Understanding chemical trends in rock surface compositions as measured by ChemCam at Gale crater, Mars: The signatures of rock coatings and rinds in LIBS laboratory data  

NASA Astrophysics Data System (ADS)

On Earth, the physical and chemical breakdown of rocky materials occurs through interactions with the atmosphere, soil, biological processes, and aqueous solutions. These interactions produce alteration features on the surfaces of rocks, which record information about the amount and types of fluids with which the rock has interacted. Alteration features can also be indicators of and habitats for microbial life in terrestrial environments. Thus, detecting rock surface alteration is an important part of the NASA Curiosity rover mission to Gale crater, Mars. The ChemCam LIBS instrument onboard Curiosity is uniquely suited to detecting and analyzing rock surface alteration. The LIBS technique uses a pulsed laser microbeam (350-550 ?m) to ablate small amounts of material from a target to form a plasma. Because some material is removed during each laser pulse, it is possible to obtain a depth profile of chemical composition by performing multiple laser pulses on one location. Each pulse returns a spectrum that represents the composition at a specific depth, with each subsequent shot sampling the composition at a slightly greater depth. Laboratory measurements of basalts have shown that each LIBS shot removes at least ~0.3-0.82 ?m/shot, suggesting a removal of ~9-25 ?m of the surface for a standard analysis of 30 shots in rocks of similar hardness. Here we present laboratory LIBS experiments on well-characterized terrestrial rock samples with coatings and rinds with the goal of understanding the signatures of such features in LIBS data from Mars. The terrestrial sample set includes a basalt with a ~0-50 ?m thick Mn-rich rock varnish and a thin (<1 mm) weathering rind and a sandy dolomite with a ~500 ?m thick Ca-rich rind. Both samples were interrogated with hundreds of LIBS shots per location three times on the unweathered interior and three times on the exterior. Results from the basalt show that compositions similar to the bulk rock composition was reached by ~50-70 shots, with the observed chemical changes suggesting both the varnish and at least some rind were penetrated. Results from the sandy dolomite do not show as clear a change from rock exterior to interior as the basalt, but a general chemical trend from exterior to interior was observed in all three depth profiles. Laboratory results suggest that depth profiles of at least 100 shots are useful for clearly identifying coatings and rinds of similar thickness to those found on Earth. However, alteration trends may still be discernible with fewer shots. On Mars, the rock Bathurst Inlet (sol 55), which was shot only 30 times per location, shows what appears to be a near-surface gradient of several elements, most notably Li. Trends similar in nature (if not composition) to the terrestrial sandy dolomite sample were also observed on raised ridge materials such as McGrath_5 (sol 234). Additional martian samples also show trends similar to coatings and rinds measured in the laboratory, suggesting that there may be surface alteration of some rocks in Gale crater.

Lanza, N.; Clegg, S. M.; Wiens, R. C.; Leveille, R. J.; Melikechi, N.; Ollila, A.; Tokar, R. L.; Newsom, H. E.; Blank, J. G.; Bridges, N. T.; Clark, B.; Deans, M. C.; Delapp, D.; Ehlmann, B. L.; Hardgrove, C. J.; Jackson, R.; Lasue, J.; McInroy, R.; Meslin, P.; Mezzacappa, A.; Team, M.

2013-12-01

273

Physical properties of poly(ether ketone ketone)\\/mica composites: effect of filler content  

Microsoft Academic Search

Poly(ether ketone ketone) (PEKK) composites filled with mica were developed using sulfonated poly(ether ketone ketone) (S-PEKK) as an interfacial modifier. Compared to PEKK, significantly improved mechanical properties were observed for the composite materials. The content of mica in composites also affects the friction behavior of these materials.

Daoji Gan; Shiqiang Lu; Caisheng Song; Zhijian Wang

2001-01-01

274

Polymer composites and porous materials prepared by thermally induced phase separation and polymer-metal hybrid methods  

NASA Astrophysics Data System (ADS)

The primary objective of this research is to investigate the morphological and mechanical properties of composite materials and porous materials prepared by thermally induced phase separation. High melting crystallizable diluents were mixed with polymers so that the phase separation would be induced by the solidification of the diluents upon cooling. Theoretical phase diagrams were calculated using Flory-Huggins solution thermodynamics which show good agreement with the experimental results. Porous materials were prepared by the extraction of the crystallized diluents after cooling the mixtures (hexamethylbenzene/polyethylene and pyrene/polyethylene). Anisotropic structures show strong dependence on the identity of the diluents and the composition of the mixtures. Anisotropic crystal growth of the diluents was studied in terms of thermodynamics and kinetics using DSC, optical microscopy and SEM. Microstructures of the porous materials were explained in terms of supercooling and dendritic solidification. Dual functionality of the crystallizable diluents for composite materials was evaluated using isotactic polypropylene (iPP) and compatible diluents that crystallize upon cooling. The selected diluents form homogeneous mixtures with iPP at high temperature and lower the viscosity (improved processability), which undergo phase separation upon cooling to form solid particles that function as a toughening agent at room temperature. Tensile properties and morphology of the composites showed that organic crystalline particles have the similar effect as rigid particles to increase toughness; de-wetting between the particle and iPP matrix occurs at the early stage of deformation, followed by unhindered plastic flow that consumes significant amount of fracture energy. The effect of the diluents, however, strongly depends on the identity of the diluents that interact with the iPP during solidification step, which was demonstrated by comparing tetrabromobisphenol-A and phthalic anhydride. A simple method to prepare composite surfaces that can change the wettability in response to the temperature change was proposed and evaluated. Composite surfaces prepared by nanoporous alumina templates filled with polymers showed surface morphology and wettability that depend on temperature. This effect is attributed to the significant difference in thermal conductivity and the thermal expansion coefficient between the alumina and the polymers. The reversibility in thermal response depends on the properties of the polymers.

Yoon, Joonsung

275

Systems With Variable Composition: The Chemical Potential Chemistry 223  

E-print Network

or 2) by changing the composition through chemical reaction. Nonetheless, as far as state functions, number of moles, etc.) and where µi,op is called the opposing chemical potential (and is analogous to the opposing pres- sure). For reversible processes, the opposing chemical potential equals the chemical

Ronis, David M.

276

Chemically coupled hydroxyapatite-polyethylene composites: processing and characterisation  

Microsoft Academic Search

Hydroxyapatite (HA)-reinforced polyethylene was developed as a bone replacement material. In order to improve bonding between HA and polyethylene, and hence to increase mechanical properties of the composite, chemical treatments of HA and polyethylene were investigated and new composites manufactured. Two approaches were employed in this investigation: the use of silane-treated HA as the filler, and the application of polymer

M Wang; S Deb; W Bonfield

2000-01-01

277

Surface morphology and ferroelectric properties of compositional gradient PZT thin films prepared by chemical solution deposition process  

NASA Astrophysics Data System (ADS)

A series of PbTiO3/PbZrxTil-xO3 (PT/PZT) and PbZrO3/PbZrxTil-xO3 (PZ/PZT) compositional gradient thin films are obtained by chemical solution decomposition (CSD) method. The influences of buffer layers on surface morphology are investigated. Thin films with buffer layer are able to maintain the perovskite structure with (1 1 1)-preferred orientation. The surface microstructure and ferroelectric properties of the PZT thin films differs significantly depending on the use of PT or PZ buffer layers. When the PT buffer layer has five layers, the root mean square roughness (RMS) [17.7 nm] and remnant polarization (Pr) [35.83 ?C/cm2] are maximized. On the other hand, when PZ buffer layer has one layer, the RMS [3.67 nm] and Pr [26.08 ?C/cm2] are also maximized. The down-graded (Zr composition varying from 0.6 at the bottom surface to 0.4 at top surface) thin films exhibit larger surface roughness and better ferroelectric property than up-graded (Zr composition varying from 0.4 at the bottom surface to 0.6 at top surface) thin films. Therefore, different buffer layer determines different surface morphology. It is concluded that the ferroelectric property of the gradient thin films not only depends on its composition structure, but can also be controlled by the surface morphology. The results indicate that the PZT films with better ferroelectric property should have larger surface roughness.

He, Gang; Zhang, Yao; Peng, Chao; Li, Xiaomeng

2013-10-01

278

Materials Bound by Non-Chemical Forces: External Fields and the Quantum Vacuum  

E-print Network

We discuss materials which owe their stability to external fields. These include: 1) external electric or magnetic fields, and 2) quantum vacuum fluctuations in these fields induced by suitable boundary conditions (the Casimir effect). Instances of the first case include the floating water bridge and ferrofluids in magnetic fields. An example of the second case is taken from biology where the Casimir effect provides an explanation of the formation of stacked aggregations or "rouleaux" by negatively charged red blood cells. We show how the interplay between electrical and Casimir forces can be used to drive self-assembly of nano-structured materials, and could be generalized both as a probe of Casimir forces and as a means of manufacturing nanoscale structures. Interestingly, all the cases discussed involve the generation of the somewhat exotic negative pressures. We note that very little is known about the phase diagrams of most materials in the presence of external fields other than those represented by the macroscopic scalar quantities of pressure and temperature. Many new and unusual states of matter may yet be undiscovered.

John Swain; Allan Widom; Yogendra Srivastava

2014-04-29

279

Deposition of microcrystalline silicon prepared by hot-wire chemical-vapor deposition: The influence of the deposition parameters on the material properties and solar cell performance  

NASA Astrophysics Data System (ADS)

Microcrystalline silicon (?c-Si:H) of superior quality can be prepared using the hot-wire chemical-vapor deposition method (HWCVD). At a low substrate temperature (TS) of 185 °C excellent material properties and solar cell performance were obtained with spin densities of 6×1015cm-3 and solar cell efficiencies up to 9.4%, respectively. In this study we have systematically investigated the influence of various deposition parameters on the deposition rate and the material properties. For this purpose, thin films and solar cells were prepared at specific substrate and filament temperatures and deposition pressures (pD), covering the complete range from amorphous to highly crystalline material by adjusting the silane concentration. The influence of these deposition parameters on the chemical reactions at the filament and in the gas phase qualitatively explains the behavior of the structural composition and the formation of defects. In particular, we propose that the deposition rate is determined by the production of reactive species at the filament and a particular atomic-hydrogen-to-silicon ratio is found at the microcrystalline/amorphous transition. The structural, optical, and electronic properties were studied using Raman and infrared spectroscopies, optical-absorption measurements, electron-spin resonance, and dark and photoconductivities. These experiments show that higher TS and pD lead to a deterioration of the material quality, i.e., much higher defect densities, oxygen contaminations, and SiH absorption at 2100cm-1. Similar to plasma enhanced chemical-vapor deposition material, ?c-Si:H solar cells prepared with HW i layers show increasing open circuit voltages (Voc) with increasing silane concentration and best performance is achieved near the transition to amorphous growth. Such solar cells prepared at low TS exhibit very high Voc up to 600 mV and fill factors above 70% with i layers prepared by HWCVD.

Klein, Stefan; Finger, Friedhelm; Carius, Reinhard; Stutzmann, Martin

2005-07-01

280

Chemical composition of lake sediments along a pollution gradient in a Subarctic watercourse  

Microsoft Academic Search

Sediment cores were collected from seven lakes in the Subarctic Pasvik watercourse, polluted by sewage waters and air emissions from the Pechenganickel Metallurgical Company, in order to study chemical composition and estimate the intensity of pollution by taking into account background concentration of elements and the vertical and spatial distribution of their contents in cores and surficial layers of sediments.

Vladimir Dauvalter; Nikolay Kashulin; Sergey Sandimirov; Petr Terentjev; Dmitry Denisov; Per-Arne Amundsen

2011-01-01

281

Compositions and chemical bonding in ceramics by quantitative electron energy-loss spectrometry  

SciTech Connect

Quantitative electron energy-loss spectrometry was applied to a range of ceramic materials at a spatial resolution of <5 nm. Analysis of Fe L{sub 23} white lines indicated a low-spin state with a charge transfer of {approximately}1.5 electrons/atom onto the Fe atoms implanted into (amorphized) silicon carbide. Gradients of 2 to 5% in the Co:O stoichiometry were measured across 100-nm-thick Co{sub 3}O{sub 4} layers in an oxidized directionally solidified CoO-ZrO{sub 2} eutectic, with the highest O levels near the ZrO{sub 2}. The energy-loss near-edge structures were dramatically different for the two cobalt oxides; those for CO{sub 3}O{sub 4} have been incorrectly ascribed to CoO in the published literature. Kinetically stabilized solid solubility occurred in an AlN-SiC film grown by low-temperature molecular beam epitaxy (MBE) on {alpha}(6H)-SiC, and no detectable interdiffusion occurred in couples of MBE-grown AlN on SiC following annealing at up to 1750C. In diffusion couples of polycrystalline AlN on SiC, interfacial 8H sialon (aluminum oxy-nitride) and pockets of Si{sub 3}N{sub 4}-rich {beta}{prime} sialon in the SiC were detected.

Bentley, J.; Horton, L.L. [Oak Ridge National Lab., TN (United States); McHargue, C.J. [Tennessee Univ., Knoxville, TN (United States); McKernan, S.; Carter, C.B. [Minnesota Univ., Minneapolis, MN (United States). Dept. of Chemical Engineering; Revcolevschi, A. [Univ. de Paris-Sud, Lab. de Chemie des Solides (France); Tanaka, S.; Davis, R.F. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Materials Science and Engineering

1993-12-31

282

Aeroelastic tailoring of composite materials  

E-print Network

LIST OF FIGURES IiiTRODUCTI ON ST!!UCTURAL RESPONSE Deformation of Uniformly Stressed Isotropic and Anisotropic Plates Characterization of Composite Laminates . Effect of Material Parameters APPLICATIONS Aircraft Propellers Ship Propell rs... com- pliances with laminate rotation 39 15 Variation of (A) extensional ard (8) bending compliances with 0' ply rotation . . . . . . . . . . . . . . . . 40 16 Incremental aerodynamic forces on a typical blade element 43 17 Propeller velocity...

Rogers, Jesse Byron

2012-06-07

283

Defining the chemical role of H2O in mantle melts: Effect of melt composition and H2O content on the activity of SiO2  

Microsoft Academic Search

Quantifying the influence of volatiles (H2O, CO2) on the chemistry of mantle melts is a critical aspect of understanding the petrogenesis of arc magmas. A significant amount of experimental work done on the effect of H2O on the solidii of various mantle compositions, as well as on multiple saturation points of various primitive melts, has shown that H2O stabilizes olivine

G. Moore; K. Roggensack

2007-01-01

284

Chemical compatibility of cartridge materials  

NASA Technical Reports Server (NTRS)

This twelve month progress report deals with the chemical compatibility of semiconductor crystals grown in zero gravity. Specifically, it studies the chemical compatibility between TZM, a molybdenum alloy containing titanium and zirconium, and WC 103, a titanium alloy containing Niobium and Hafnium, and Gallium arsenide (GaAs) and Cadmium Zinc Tellurite (CdZnTe). Due to the health hazards involved, three approaches were used to study the chemical compatibility between the semiconductor and cartridge materials: reaction retort, thermogravimetric analysis, and bulk cylindrical cartridge containers. A scanning electron microscope with an energy dispersive X-ray analyzer was used to examine all samples after testing. The first conclusion drawn is that reaction rates with TZM were not nearly as great as they were with WC 103. Second, the total reaction between GaAs and WC 103 was almost twice that with TZM. Therefore, even though WC 103 is easier to fabricate, at least half of the cartridge thickness will be degraded if contact is made with one of the semiconductor materials leading to a loss of strength properties.

Wilcox, Roy C.; Zee, R. H.

1991-01-01

285

Chemical composition of Galactic H II regions.  

NASA Astrophysics Data System (ADS)

A review of the chemical compositions of M8, M17 and M42 (Orion) is presented. Observational evidence on the presence of spatial temperature variations inside H II regions is presented; these variations can be explained by photoionization models of nebulae with uniform distributions of dust and chemical composition. Possible causes of these temperature variations are analyzed. Abundance tables with probable errors (1?) for Orion, M8 and M17 are presented. These abundances are compared with those of the Sun and B stars of the solar neighborhood. The abundances of Galactic H II regions are compared with those of extragalactic H II regions; the enrichment of the carbon abundance and the ?Y/?Z value are briefly discussed.

Peimbert, M.

1993-11-01

286

Chemical composition of sediments from White Sea, Russian Arctic  

NASA Astrophysics Data System (ADS)

The White Sea, the only Russian inland sea, is located on the north of outlying districts of the European part of Russia, belongs to Arctic Ocean. Area of water of sea occupies about 90 tousend square kilometers. The sea can be divided into some general parts: neck, funnel, basin and 4 Bays: Dvina Bay, Kandalaksha Bay, Mezen Bay and Onega Bay. The purpose of this work was geochemical mapping of the surface sediments of this area. The main tasks were: compilation data base of element composition of the surface sediments, geochemical mapping of each element, research of the anormal concentration of elements on the surface. To detect the content of chemical elements several methods were used: atomic absorption spectrometry (P.P. Shirshov Institute of Oceanology); neutron activation analysis (Vernadsky Institute of Geochemistry and Analytical Chemistry), total and organic carbon analysis, photometric method to detection Si, Al, P (P.P. Shirshov Institute of Oceanology). Bulk composition is one of the fundamental characteristics of sediments and bottom deposites of modern basins. Coarse-grained sediments with portion of pelitic component <50% is spread on the shallow area (Kandalaksha Bay), in areas with high hydrodynamic activity of near-bottom water. Under the conditions of their low activity, fine-grained facies are common(>80%). Character of elements distribution correlates with facial distribution of sediments from White Sea. According to litologic description, bottom surface of Dvina Bay is practically everywhere covered by layer of fine-grained sand. In the border area between Dvina Bay and White Sea basin on terraced subwater slope aleurite politic silts are abundant. They tend to exhange down the slope to clay silts. In Onega Bay fractions of non-deposition are observed. They are characterized by wide spread of thin blanket poorgraded sediments, which are likely to be relic. Relief of Kandalakscha Bay bottom is presented as alternation of abyssal fosses (near 300 m) with silles and elevations (<20 m), and also numerous islands. Thus variety of sediment composition is observed here - from rules and gravels to fine-grained clay silts [1]. The map of distribution of chemical elements was created by using bulk composition data with the help of program ArcView. Mn distribution in sedimentation mass is largely determed by influence of redox diagenesis. Reactive form of Mn dominates over less moving, litogenic form in sedimation mass of White Sea. Litogenic form remains in sediment, reactive form moves into silt near-bottom water, resulting Mn migration both in sediment and near-bottom layer of marine water. Mn oxidizes on the contact with oxygen of marine water and alters into insoluble form MnO2, causing Mn enrichment of surface layer of sediments. Highly movable silt deposit MnO2 and enriched by Mn suspension are moved by underflow and accumulate in bottom depressions and in central part of the sea, which is quite wide from both places of original sedimentation and run off sources [2]. Thus, the interrelation between granulometric composition of sediment and materials concentration can be shown by the example of Mn. Local conditions, leading to accumulation of clastic components, are: 1. Rise of content in sand owning to separation of heavy minerals 2. Rise of content in surface, mainly sandy clay sediments owning to presence of concretions 3. Rise of content in lower bunches roof owning to diagenetic contraction. Authors thank academic Lisitsyn for encourage, Andrey Apletalin for valuable help, and everybody, who helped in field and laboratory research of the White sea sediments. Work was being done under the auspices of Russian foundation of basic research (grants 09-05-10081, 09-05-00658 and 08-05-00860), RSA presidiums program of 17 fundamental researches (project 17.1). References: 1.Kuzmina T., Lein A., Lutchsheva L., Murdmaa I., Novigatsky A., Shevchenko V. Chemical composition of White Sea's sediments // Litology and mineral deposits . 2009. - ? 2. - P 115-132. 2.Nevessky E., Medvedev V. , Kalin

Gamza, Olga; Shevchenko, Vladimir; Novigatsky, Aleksandr

2010-05-01

287

Relating ion binding by fulvic and humic acids to chemical composition and molecular size. 1. Proton binding.  

PubMed

Proton binding by a soil fulvic acid, humic acid, and a set of size fractions of the humic acid was studied as a function of pH and ionic strength by potentiometric titrations. The negative charge of the humic substances resulting from deprotonation of acidic functional groups generally increased with increasing pH and increasing ionic strength. At any given pH and ionic strength, the fulvic acid fraction exhibited much higher negative charge than the humic acid fraction. For the size-fractionated humic acids, negative charge decreased steadily with increasing apparent molecular weight, as determined by size exclusion chromatography. Observed differences in proton binding by the various humic substances corresponded well to differences in functional group composition, which has been extensively characterized in a previous study using a combination of analytical techniques. The proton binding behavior of the humic substances was described very well by the consistent NICA-Donnan model. However, when all adjustable model parameters were determined using a least-squares minimization technique without introducing parameter constraints, the values of some parameters turned out physically and chemically unreasonable. Therefore, we propose to derive some model parameters from chemical characterization results obtained by size exclusion chromatography and solid-state 13C NMR spectroscopy. Using this approach, we obtained excellent descriptions of all titration data, and the model parameter values were more consistent and chemically reasonable. Our results demonstrate that characterization results of humic substances can be used in NICA-Donnan modeling to reduce the number of free fitting parameters without arbitrary constraints and, thereby, obtaining a more reliable database for environmental modeling. PMID:11432555

Christl, I; Kretzschmar, R

2001-06-15

288

Date fruit: chemical composition, nutritional and medicinal values, products.  

PubMed

Date fruit has served as a staple food in the Arab world for centuries. Worldwide production of date fruit has increased almost threefold over the last 40 years, reaching 7.68 million tons in 2010. Date fruit can provide many essential nutrients and potential health benefits to the consumer. Date fruit goes through four ripening stages named kimri, khalal, rutab and tamer. The main chemical components of date fruit include carbohydrates, dietary fibre, enzymes, protein, fat, minerals, vitamins, phenolic acids and carotenoids. The chemical composition of date fruit varies according to ripening stage, cultivar, growing environment, postharvest conditions, etc. The nutritional and medicinal activities of date fruit are related to its chemical composition. Many studies have shown that date fruit has antioxidant, antimutagenic, anti-inflammatory, gastroprotective, hepatoprotective, nephroprotective, anticancer and immunostimulant activities. Various date fruit-based products such as date syrup, date paste, date juice and their derived products are available. Date by-products can be used as raw materials for the production of value-added products such as organic acids, exopolysaccharides, antibiotics, date-flavoured probiotic-fermented dairy produce, bakery yeasts, etc. In this paper the chemical composition and nutritional and medicinal values of date fruit as well as date fruit-based products are reviewed. PMID:23553505

Tang, Zhen-Xing; Shi, Lu-E; Aleid, Salah M

2013-08-15

289

3-D textile reinforcements in composite materials  

SciTech Connect

Laminated composite materials have been used in structural applications since the 1960s. However, their high cost and inability to accommodate fibers in the laminate`s thickness direction greatly reduce their damage tolerance and impact resistance. The second generation of materials--3-D textile reinforced composites--offers significant cost reduction, and by incorporating reinforcement in the thickness direction, dramatically increases damage tolerance and impact resistance. However, methods for predicting mechanical properties of 3-D textile reinforced composite materials tend to be more complex. These materials also have disadvantages--particularly in regard to crimps in the yarns--that require more research. Textile preforms, micro- and macromechanical modeling, manufacturing processes, and characterization all need further development. As researchers overcome these problems, this new generation of composites will emerge as a highly competitive family of materials. This book provides a state-of-the-art account of this promising technology. In it, top experts describe the manufacturing processes, highlight the advantages, identify the main applications, analyze methods for predicting mechanical properties, and detail various reinforcement strategies, including grid structure, knitted fabric composites, and the braiding technique. Armed with the information in this book, readers will be prepared to better exploit the advantages of 3-D textile reinforced composites, overcome its disadvantages, and contribute to the further development of the technology.

Miravete, A. [Univ. of Zaragoza (Spain)

1999-11-01

290

Microcrack Quantification in Composite Materials by a Neural Network Analysis of Ultrasound Spectral Data  

NASA Technical Reports Server (NTRS)

Intra-ply microcracking in unlined composite pressure vessels can be very troublesome to detect and when linked through the thickness can provide leak paths that may hinder mission success. The leaks may lead to loss of pressure/propellant, increased risk of explosion and possible cryo-pumping into air pockets within the laminate. Ultrasonic techniques have been shown capable of detecting the presence of microcracking and in this work they are used to quantify the level of microcracking. Resonance ultrasound methods are utilized with artificial neural networks to build a microcrack prediction/measurement tool. Two networks are presented, one unsupervised to provide a qualitative measure of microcracking and one supervised which provides a quantitative assessment of the level of microcracking. The resonant ultrasound spectroscopic method is made sensitive to microcracking by tuning the input spectrum to the higher frequency (shorter wavelength) components allowing more significant interaction with the defects. This interaction causes the spectral characteristics to shift toward lower amplitudes at the higher frequencies. As the density of the defects increases more interactions occur and more drastic amplitude changes are observed. Preliminary experiments to quantify the level of microcracking induced in graphite/epoxy composite samples through a combination of tensile loading and cryogenic temperatures are presented. Both unsupervised (Kohonen) and supervised (radial basis function) artificial neural networks are presented to determine the measurable effect on the resonance spectrum of the ultrasonic data taken from the samples.

Walker, James L.; Russell, Samuel S.; Suits, Michael W.

2003-01-01

291

Property changes induced by the space environment in composite materials on LDEF: Solar array materials passive LDEF experiment A0171 (SAMPLE)  

NASA Technical Reports Server (NTRS)

Surface modifications to composite materials induced by long term exposure in low earth orbit (LEO) were dominated by atomic oxygen erosion and micrometeoroid and space debris impacts. As expected, calculated erosion rates were peculiar to material type and within the predicted order of magnitude. Generally, about one ply of the carbon fiber composites was eroded during the 70 month LDEF experiment. Matrix erosion was greater than fiber erosion and was more evident for a polysulfone matrix than for epoxy matrices. Micrometeoroid and space debris impacts resulted in small (less than 1mm) craters and splattered contaminants on all samples. Surfaces became more diffuse and darker with small increases in emissivity and absorption. Tensile strength decreased roughly with thickness loss, and epoxy matrices apparently became slightly embrittled, probably as a result of continued curing under UV and/or electron bombardment. However, changes in the ultimate yield stress of the carbon reinforced epoxy composites correlate neither with weave direction nor fiber type. Unexpected developments were the discovery of new synergistic effects of the space environment in the interaction of atomic oxygen and copious amounts of contamination and in the induced luminescence of many materials.

1993-01-01

292

Fungal degradation of fiber-reinforced composite materials  

NASA Technical Reports Server (NTRS)

As described in a previous report, a fungal consortium isolated from degraded polymeric materials was capable of growth on presterilized coupons of five composites, resulting in deep penetration into the interior of all materials within five weeks. Data describing the utilization of composite constituents as nutrients for the microflora are described in this article. Increased microbial growth was observed when composite extract was incubated with the fungal inoculum at ambient temperatures. Scanning electron microscopic observation of carbon fibers incubated with a naturally developed population of microorganisms showed the formation of bacterial biofilms on the fiber surfaces, suggesting possible utilization of the fiber chemical sizing as carbon and energy sources. Electrochemical impedance spectroscopy was used to monitor the phenomena occurring at the fiber-matrix interfaces. Significant differences were observed between inoculated and sterile panels of the composite materials. A progressive decline in impedance was detected in the inoculated panels. Several reaction steps may be involved in the degradation process. Initial ingress of water into the resin matrix appeared to be followed by degradation of fiber surfaces, and separation of fibers from the resin matrix. This investigation suggested that composite materials are susceptible to microbial attack by providing nutrients for growth.

Gu, J. D.; Lu, C.; Mitchell, R.; Thorp, K.; Crasto, A.

1997-01-01

293

Carbon Nano Tube Composites with Chemically Functionalized Plant Oils  

NASA Astrophysics Data System (ADS)

Carbon Nano Tube Composites with Chemically Functionalized Plant Oil Wim Thielemans, R., P. Wool, V. Barron and W. Blau Multi-Wall Carbon Nano Tubes (MWCNT) made by the Kratchmer-Huffman CCVD process were found to interact and solubilize by slow mechanical stirring, with chemically functionalized plant oils, such as acrylated, epoxidized and maleinated triglycerides (TG) derived from plant oils. The chemical functionality on the TG imparted amphiphilic properties to the oils which allows them to self-assemble on the nanotubes, promoting both dissolution and the ability to make nanocomposites with unusual properties. Once in solution, the MWCT can be processed in a variety of methods, in particular to make composites with enhanced mechanical, fracture and thermal properties. Since the tensile modulus of MWs is about 1 TPa and a vector percolation analysis indicated tensile strengths of 50-100 GPa, we obtain significantly improved properties with even small amounts (1-3the glass transition temperature of the composite by about 20 oC, and the tensile modulus by about 11significant effects on the fracture stress can be obtained due to the both the influence of the strength and length of the MWNT at the crack tip. The ability of the oils to self-assemble on the carbon nanotube surfaces also makes them ideal candidates for self-healing materials. The properties with different functionalized oils will be reported. Supported by EPA, DoE and ISF

Thielemans, Wim; Wool, Richard P.; Blau, Werner; Barron, Valerie

2003-03-01

294

Gradient composite materials for artificial intervertebral discs.  

PubMed

Composites with the gradient of Young's modulus constitute a new group of biomimetic materials which affect the proper distribution of stresses between the implant and the bone. The aim of this article was to examine the mechanical properties of gradient materials based on carbon fibre-polysulfone composite, and to compare them to the properties of a natural intervertebral disc. Gradient properties were provided by different orientation or volume fraction of carbon fibres in particular layers of composites. The results obtained during in vitro tests displayed a good durability of the gradient materials put under long-term static load. However, the configuration based on a change in the volume fraction of the fibres seems more advantageous than the one based on a change of the fibres' orientation. The materials under study were designed to replace the intervertebral disc. The effect of Young's modulus of the material layers on the stress distribution between the tissue and the implant was analyzed and the biomimetic character of the gradient composites was stated. Unlike gradient materials, the pure polysulfone and the non-gradient composite resulted in the stress concentration in the region of nucleus pulposus, which is highly disadvantageous and does not occur in the stress distribution of natural intervertebral discs. PMID:25306938

Migacz, Katarzyna; Ch?opek, Jan; Morawska-Chochó?, Anna; Ambroziak, Maciej

2014-01-01

295

Identification of lead chemical form in mine waste materials by X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy (XAS) provides a direct means for measuring lead chemical forms in complex samples. In this study, XAS was used to identify the presence of plumbojarosite (PbFe6(SO4)4(OH)12) by lead L3-edge XANES spectra in mine waste from a small gold mining operation in Fiji. The presence of plumbojarosite in tailings was confirmed by XRD but XANES gave better resolution. The potential for human uptake of Pb from tailings was measured using a physiologically based extract test (PBET), an in-vitro bioaccessibility (BAc) method. The BAc of Pb was 55%. Particle size distribution of tailings indicated that 40% of PM10 particulates exist which could be a potential risk for respiratory effects via the inhalation route. Food items collected in the proximity of the mine site had lead concentrations which exceed food standard guidelines. Lead within the mining lease exceeded sediment guidelines. The results from this study are used to investigate exposure pathways via ingestion and inhalation for potential risk exposure pathways of Pb in that locality. The highest Pb concentration in soil and tailings was 25,839 mg/kg, exceeding the Australian National Environment Protection Measure (NEPM) soil health investigation levels.

Taga, Raijeli L.; Zheng, Jiajia; Huynh, Trang; Ng, Jack; Harris, Hugh H.; Noller, Barry

2010-06-01

296

The Chemical Composition of Texas Honey and Pecans  

E-print Network

TEXAS AGRICULTURAL EXPERIMENT STATION AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS W. B. BIZZELL, President BULLETIN NO. 272 JANUARY, 192 1 --- - DIVISION OF CHEMISTRY THE CHEMICAL COMPOSITION OF TEXAS HONEY AND PECANS *. - B. YOUNGBLOOD...~ted States Department of Agriculture. CONTENTS . PAGE Introduction ................................................ 5 .......................................... Methods of Analysis 5 ....................................... Flavor of Honey ........ : 5...

Fraps, G. S. (George Stronach)

1921-01-01

297

Chemical Corrosion Effect on Wood and Wood–Plastic Composites  

Microsoft Academic Search

Effect of chemical corrosion on the tensile strengths of five types of Bangladeshi timbers (kadom, simul, koroi, mango, and debdaro) and their composites has been evaluated. Wood–plastic composites (WPC) formed by the gamma-radiation induction polymerization of butylmethacrylate (BMA) with those timbers show better resistance to chemical corrosion attack than the parent timbers. Enhanced mechanical properties such as tensile strength of

M. A. Khan; K. M. Idriss Ali; M. U. Ahmed

1993-01-01

298

Screening of chemical composition, antimicrobial and antioxidant activities of Artemisia essential oils  

Microsoft Academic Search

The chemical composition of essential oils isolated from aerial parts of seven wild sages from Western Canada –Artemisia absinthium L., Artemisia biennis Willd., Artemisia cana Pursh, Artemisia dracunculus L., Artemisia frigida Willd., Artemisia longifolia Nutt. and Artemisia ludoviciana Nutt., was investigated by GC–MS. A total of 110 components were identified accounting for 71.0–98.8% of the oil composition. High contents of

Daíse Lopes-Lutz; Daniela S. Alviano; Celuta S. Alviano; Paul P. Kolodziejczyk

2008-01-01

299

Determination of moisture effects on impact properties of composite materials  

Microsoft Academic Search

Many applications of structural materials involving composites include impact or dynamic loading in a humid environment. Composite materials are known to degrade when subjected to humid conditions, and therefore the humidity confounds the difficulty of determining the high strain rate behavior of composites. Several researchers have found that water absorption by composites causes degradation of matrix dominated quasi-static properties. However,

E. Woldesenbet; N. Gupta; J. R. Vinson

2002-01-01

300

The effects of fiber waviness on the compressive response of fiber reinforced composite materials  

E-print Network

THE EFFECI'S OF FIBER WAVINESS ON THE COMPRESSIVE RESPONSE OF FIBER REINFORCED COMPOSITE MATERIALS A Thesis by JOHN JEROME DAVIS Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1989 Major Subject: Aerospace Engineering THE EFFECTS OF FIBER WAVINESS ON THE COMPRESSIVE RESPONSE OF FIBER REINFORCED COMPOSITE MATERIALS A Thesis by JOHN JEROME DAVIS Approved as to style and content by...

Davis, John Jerome

2012-06-07

301

DOE/MSU composite material fatigue database: Test methods, materials, and analysis  

SciTech Connect

This report presents a detailed analysis of the results from fatigue studies of wind turbine blade composite materials carried out at Montana State University (MSU) over the last seven years. It is intended to be used in conjunction with the DOE/MSU composite Materials Fatigue Database. The fatigue testing of composite materials requires the adaptation of standard test methods to the particular composite structure of concern. The stranded fabric E-glass reinforcement used by many blade manufacturers has required the development of several test modifications to obtain valid test data for materials with particular reinforcement details, over the required range of tensile and compressive loadings. Additionally, a novel testing approach to high frequency (100 Hz) testing for high cycle fatigue using minicoupons has been developed and validated. The database for standard coupon tests now includes over 4,100 data points for over 110 materials systems. The report analyzes the database for trends and transitions in static and fatigue behavior with various materials parameters. Parameters explored are reinforcement fabric architecture, fiber content, content of fibers oriented in the load direction, matrix material, and loading parameters (tension, compression, and reversed loading). Significant transitions from good fatigue resistance to poor fatigue resistance are evident in the range of materials currently used in many blades. A preliminary evaluation of knockdowns for selected structural details is also presented. The high frequency database provides a significant set of data for various loading conditions in the longitudinal and transverse directions of unidirectional composites out to 10{sup 8} cycles. The results are expressed in stress and strain based Goodman Diagrams suitable for design. A discussion is provided to guide the user of the database in its application to blade design.

Mandell, J.F.; Samborsky, D.D. [Montana State Univ., Bozeman, MT (United States). Dept. of Chemical Engineering

1997-12-01

302

Mechanical fastening of composite materials  

NASA Astrophysics Data System (ADS)

High-sensitivity moire interferometry was used to obtain the stress/strain distribution in the vicinity of mechanically fastened hole arrays in a glass/epoxy thermoset composite material. Experimental results are presented for three fastener configurations: the tandem configuration (two holes in a row parallel to the load direction), the parallel configuration (two fastening holes in a row perpendicular to the load direction), and the three-hole fastener array with all three holes equally loaded. The advantage of utilizing as multihole array in a connection rather than a single pin-loaded hole is demonstrated.

Zimmerman, K. B.

1992-08-01

303

Detection of adulteration of pumpkin seed oil by analysis of content and composition of specific ?7-phytosterols  

Microsoft Academic Search

A simple and accurate method for the determination of phytosterols by capillary gas chromatography was developed for the\\u000a analysis of the seeds and oil of the pumpkin Cucurbita pepo L., the naked seed variety growing in the southern Styrian parts of Austria. After extraction of the oil and saponification,\\u000a the remaining unsaponifiable material was isolated and purified using silica gel

Alexandra Mandl; Gregor Reich; W. Lindner

1999-01-01

304

Composite Materials for Wind Power Turbine Blades  

NASA Astrophysics Data System (ADS)

Renewable energy resources, of which wind energy is prominent, are part of the solution to the global energy problem. Wind turbine and the rotorblade concepts are reviewed, and loadings by wind and gravity as important factors for the fatigue performance of the materials are considered. Wood and composites are discussed as candidates for rotorblades. The fibers and matrices for composites are described, and their high stiffness, low density, and good fatigue performance are emphasized. Manufacturing technologies for composites are presented and evaluated with respect to advantages, problems, and industrial potential. The important technologies of today are prepreg (pre-impregnated) technology and resin infusion technology. The mechanical properties of fiber composite materials are discussed, with a focus on fatigue performance. Damage and materials degradation during fatigue are described. Testing procedures for documentation of properties are reviewed, and fatigue loading histories are discussed, together with methods for data handling and statistical analysis of (large) amounts of test data. Future challenges for materials in the field of wind turbines are presented, with a focus on thermoplastic composites, new structural materials concepts, new structural design aspects, structural health monitoring, and the coming trends and markets for wind energy.

Brøndsted, Povl; Lilholt, Hans; Lystrup, Aage

2005-08-01

305

Carbon Nano Tube Composites with Chemically Functionalized Plant Oils  

Microsoft Academic Search

Carbon Nano Tube Composites with Chemically Functionalized Plant Oil Wim Thielemans, R., P. Wool, V. Barron and W. Blau Multi-Wall Carbon Nano Tubes (MWCNT) made by the Kratchmer-Huffman CCVD process were found to interact and solubilize by slow mechanical stirring, with chemically functionalized plant oils, such as acrylated, epoxidized and maleinated triglycerides (TG) derived from plant oils. The chemical functionality

Wim Thielemans; Richard P. Wool; Werner Blau; Valerie Barron

2003-01-01

306

New demands on manufacturing of composite materials  

SciTech Connect

Traditionally the field of advanced composites has been dominated by the needs of the aerospace industry. This has strongly influenced the materials and processes developed. However, during the last few years, a shift of emphasis into other engineering areas has been obvious. Branches such as the mechanical industry, ground transportation, the building industry and the leisure industry are today defining many of the new areas of application for these materials. In these applications fiber-reinforced composites are not just used in large structures but also in crucial small complex-shaped elements of larger machinery in order to improve overall performance. To satisfy these new demands, it is essential to develop innovative material systems and processing techniques which enable the production of composite parts with complex geometries at reasonable cost and with high precision. Most likely the solution to this task lies in the closely integrated development of the material system and the manufacturing method. Several different approaches are today taken in order to reach this goal for composite materials. Furthermore, it is nowadays important that the introduction of any new material or application, especially for high volume production, be accompanied by a thorough life-cycle and environmental plan.

Manson, J.A.E. [Ecole Polytechnique Federale de Lausanne (Switzerland). Lab. de Technologie des Composites et Polymeres

1994-12-31

307

Fat Content, Caloric Value, Cholesterol Content, and Fatty Acid Composition of Raw and Cooked Ostrich Meat  

Microsoft Academic Search

The influence of cooking on the ether-extractable fat content, caloric value, lipid content, cholesterol content, and fatty acid composition of theiliofibularismuscle from the ostrich carcass has been studied. A comparison was also made between values obtained for ostrich and those of beef and chicken. The ether-extractable fat content, caloric value, lipid content, and cholesterol content of ostrich meat were increased

James Sales; Dewet Marais; Marita Kruger

1996-01-01

308

http://jtc.sagepub.com Composite Materials  

E-print Network

http://jtc.sagepub.com Composite Materials Journal of Thermoplastic DOI: 10.1177/0892705708089473 2008; 21; 209Journal of Thermoplastic Composite Materials Qinglin Wu Sun-Young Lee, In-Aeh Kang, Geum://www.sagepublications.com at: can be foundJournal of Thermoplastic Composite MaterialsAdditional services and information

309

Properties of composite materials for cryogenic applications  

Microsoft Academic Search

Composite materials are used in a wide variety of cryogenic applications because of their unique and highly tailorable properties. These cryogenic applications of composites may be, for the sake of discussion, classified as support structures, vessels, or electrical insulation. Examples of these applications are presented, with a brief discussion of the critical material properties associated with each application. Composite material

J. B Schutz

1998-01-01

310

ULTRASONIC CHARACTERIZATION OF ADVANCED COMPOSITE MATERIALS  

Microsoft Academic Search

With increased use of composite materials in critical structural applications it is more important than ever to independently assure structural integrity. Complexity of the advanced composite materials including layered and bonded structures represents challenges in developing optimized ultrasonic tests. Traditional ultrasonic NDT methods are inappropriate and often misleading when applied to anisotropic and nonhomogeneous composite materials. In advanced technology applications

B. Boro Djordjevic

311

Composite materials based on wastes of flat glass processing  

Microsoft Academic Search

Glass mirrors scrap and poly (vinyl) butiral waste (PVB) obtained from flat glass processing plants were investigated as raw materials to produce composites. The emphasis was on studying the influence of milled glass mirror waste contents on properties of composites produced with PVB. The characterization involved: elongation under rupture, water absorption, tensile strength and elastic modulus tests. The results showed

A. V. Gorokhovsky; J. I. Escalante-Garcia; G. Yu. Gashnikova; L. P. Nikulina; S. E. Artemenko

2005-01-01

312

Exposure Assessment of Chemicals from Packaging Materials  

NASA Astrophysics Data System (ADS)

A variety of chemicals may enter our food supply, by means of intentional or unintentional addition, at different stages of the food chain. These chemicals include food additives, pesticide residues, environmental contaminants, mycotox-ins, flavoring substances, and micronutrients. Packaging systems and other food-contact materials are also a source of chemicals contaminating food products and beverages. Monitoring exposure to these chemicals has become an integral part of ensuring the safety of the food supply. Within the context of the risk analysis approach and more specifically as an integral part of risk assessment procedures, the exercise known as exposure assessment is crucial in providing data to allow sound judgments concerning risks to human health. The exercise of obtaining this data is part of the process of revealing sources of contamination and assessing the effectiveness of strategies for minimizing the risk from chemical contamination in the food supply (Lambe, 2002).

Poças, Maria De Fátima; Hogg, Timothy

313

Composite materials for fusion applications  

SciTech Connect

Ceramic matrix composites, CMCs, are being considered for advanced first-wall and blanket structural applications because of their high-temperature properties, low neutron activation, low density and low coefficient of expansion coupled with good thermal conductivity and corrosion behavior. This paper presents a review and analysis of the hermetic, thermal conductivity, corrosion, crack growth and radiation damage properties of CMCs. It was concluded that the leak rates of a gaseous coolant into the plasma chamber or tritium out of the blanket could exceed design criteria if matrix microcracking causes existing porosity to become interconnected. Thermal conductivities of unirradiated SiC/SiC and C/SiC materials are about 1/2 to 2/3 that of Type 316 SS whereas the thermal conductivity for C/C composites is seven times larger. The thermal stress figure-of-merit value for CMCs exceeds that of Type 316 SS for a single thermal cycle. SiC/SiC composites are very resistant to corrosion and are expected to be compatible with He or Li coolants if the O{sub 2} concentrations are maintained at the appropriate levels. CMCs exhibit subcritical crack growth at elevated temperatures and the crack velocity is a function of the corrosion conditions. The radiation stability of CMCs will depend on the stability of the fiber, microcracking of the matrix, and the effects of gaseous transmutation products on properties. 23 refs., 14 figs., 1 tab.

Jones, R.H.; Henager, C.H. Jr.; Hollenberg, G.W.

1991-10-01

314

Evaluation of γ-oryzanol content and composition from the grains of pigmented rice-germplasms by LC-DAD-ESI/MS  

PubMed Central

Background Rice is the staple food and one of the world’s three major grain crops. Rice contains more than 100 bioactive substances including phytic acid, isovitexin, γ-oryzanol, phytosterols, octacosanol, squalene, γ-aminobutyric acid (GABA), tocopherol, tocotrienol derivatives, etc. Out of them, γ-oryzanol is known to have important biological profile such as anti-oxidants, inhibitor of cholesterol oxidation, reduce serum cholesterol levels in animals, effective in the treatment of inflammatory diseases, inhibit tumor growth, reduce blood pressure and promotes food storage stability when used as a food additive, etc. Hence in the present investigation, we aimed to evaluate the content and composition of γ-oryzanol from pigmented rice germplasms using a liquid chromatography with diode array detection and electrospray ionization-mass spectrometry (LC-DAD-ESI/MS). Findings In the present study, 33 exotic pigmented rice accessions (red, white and purple) have been evaluated. Among them, the contents of γ-oryzanol varied from 3.5 to 21.0Âmg/100Âg with a mean of 11.2Âmg/100Âg. A total of ten components of γ-oryzanol including ∆7-stigmastenyl ferulate were identified of which, cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, campesteryl ferulate and sitosteryl ferulate were identified as the major components. The mean proportions of steryl ferulates were in the descending order of 24-methylenecycloartanyl ferulate > cycloartenyl ferulate > campesteryl ferulate > sitosteryl ferulate > ∆7-campestenyl ferulate > campestanyl ferulate > sitostanyl ferulate > ∆7-stigmastenyl ferulate > stigamsteryl ferulate > ∆7-sitostenyl ferulate. Almost 11 accessions (33%) showed higher content than the control rice Chucheongbyeo and higher proportions ranged from 10 to 15Âmg/100Âg. Interestingly, the red rice accession Liberian Coll. B11/B-11 (21.0Âmg/100Âg) showed higher content γ-oryzanol than control rice Jeokjinjubyeo (19.1Âmg/100Âg) and the purple rice accession Padi Adong Dumarat, Mardi No.4376 (20.3Âmg/100Âg) showed a similar content with control rice Heugjinjubyeo (21.4Âmg/100Âg). Conclusions Most of analyzed rice accessions were found to possess higher contents of γ-oryzanol than the control rice, Chucheongbyeo. In particular, the red accessions showed highest content than the white and purple accessions. The content and composition of γ-oryzanol in 33 exotic pigmented rice accessions have been evaluated and compared significantly by the present investigation. PMID:23587158

2013-01-01

315

A composition-independent quantitative determination of the water content in silicate glasses and silicate melt inclusions by confocal Raman spectroscopy  

Microsoft Academic Search

A new approach was developed to measure the water content of silicate glasses using Raman spectroscopy, which is independent\\u000a of the glass matrix composition and structure. Contrary to previous studies, the compositional range of our studied silicate\\u000a glasses was not restricted to rhyolites, but included andesitic, basaltic and phonolitic glasses. We used 21 glasses with\\u000a known water contents for calibration.

Zoltán Zajacz; Werner Halter; Wim J. Malfait; Olivier Bachmann; Robert J. Bodnar; Marc M. Hirschmann; Charles W. Mandeville; Yann Morizet; Othmar Müntener; Peter Ulmer; James D. Webster

2005-01-01

316

Comparison of sodium content of workplace and homemade meals through chemical analysis and salinity measurements  

PubMed Central

BACKGROUND/OBJECTIVES Most Koreans consume nearly 70-80% of the total sodium through their dishes. The use of a salinometer to measure salinity is recommended to help individuals control their sodium intake. The purpose of this study was to compare sodium content through chemical analysis and salinity measurement in foods served by industry foodservice operations and homemade meals. MATERIALS/METHODS Workplace and homemade meals consumed by employees in 15 cafeterias located in 8 districts in Daegu were collected and the sodium content was measured through chemical analysis and salinity measurements and then compared. The foods were categorized into 9 types of menus with 103 workplace meals and 337 homemade meals. RESULTS Workplace meals did not differ significantly in terms of sodium content per 100 g of food but had higher sodium content via chemical analysis in roasted foods per portion. Homemade meals had higher broth salt content and higher salt content by chemical analysis per 100 g of roasted foods and hard-boiled foods. One-dish workplace meals had higher salinity (P < 0.05), while homemade broths and stews had higher sodium content (P < 0.05 and P < 0.01, respectively). The sodium content per 100 g of foods was higher in one-dish workplace meals (P < 0.05) and in homemade broths and stews (P < 0.01 and P < 0.05, respectively). CONCLUSIONS The use of a salinometer may be recommended to estimate the sodium content in foods and control one's sodium intake within the daily intake target as a way to promote cooking bland foods at home. However, estimated and actual measured values may differ.

Shin, Eun-Kyung

2014-01-01

317

Effect of Rare Earth Oxide Content on Nanograined Base Metal Electrode Multilayer Ceramic Capacitor Powder Prepared by Aqueous Chemical Coating Method  

NASA Astrophysics Data System (ADS)

The aqueous chemical coating route is highly effective in preparing BaTiO3 nanoparticles uniformly coated with additives. Such nanoparticles can be used to produce nano-grained temperature stable BaTiO3 ceramics with core-shell structure, fulfilling the need of next-generation ultrathin layer base metal electrode (BME) multilayer ceramic capacitors (MLCCs). Rare earth oxides are an important class of additives owing to their ability to fulfill both donor and acceptor roles. In this paper, the effects of Y2O3 and Ho2O3 co-dopant content on dielectric and microstructural properties were investigated. By applying chemical coating, BaTiO3-based high performance temperature stabilized ceramics with the average grain size of about 130 nm, which met the requirement of next generation BME MLCCs, were obtained.

Zhang, Yichi; Wang, Xiaohui; Kim, Jinyong; Li, Longtu

2013-02-01

318

The Chemical Composition of Maple Syrup  

ERIC Educational Resources Information Center

Maple syrup is one of several high-sugar liquids that humans consume. However, maple syrup is more than just a concentrated sugar solution. Here, we review the chemical composition of maple syrup. (Contains 4 tables and 1 figure.)

Ball, David W.

2007-01-01

319

Evaluation of heat treated wood swelling by differential scanning calorimetry in relation with chemical composition.  

E-print Network

and Bekhta 2003). Retification® is a mild pyrolysis of wood that takes place under nitrogen atmosphereEvaluation of heat treated wood swelling by differential scanning calorimetry in relation calorimetry ; fiber saturation point ; heat treatment ; swelling ; wood. DOI 10.1515/HF.2004.131 Abstract

Paris-Sud XI, Université de

320

Determination of the chemical composition of the South Pole aerosol by instrumental neutron activation analysis  

Microsoft Academic Search

Atmospheric particulate samples were collected at the geographic South pole, using cellulose and polycarbonate filters and\\u000a cascade impactors. The samples were analysed for 40 elements by instrumental neutron activation analysis. From the filter\\u000a samples atmospheric concentrations for 33 elements could be obtained. The highest atmospheric concentrations were found for\\u000a S: 49 ng\\/standard cubic meter (SCM) of air, Na: 3.3 ng\\/SCM

W. Maenhaut; W. H. Zoller

1977-01-01

321

The chemical composition of plant galls: are levels of nutrients and secondary compounds controlled by the gall-former?  

Microsoft Academic Search

The chemical composition of galled and ungalled plant tissue was compared in a series of experiments. Gall and adjacent plant\\u000a tissue was analysed for 20 species of gall-former on 11 different plant species. There were clear differences between galled\\u000a and ungalled tissue in levels of nutrients and secondary compounds. Gall tissue generally contained lower levels of nitrogen\\u000a and higher levels

S. E. Hartley

1998-01-01

322

Chemical composition of Texas surface waters, 1949  

USGS Publications Warehouse

This report is the fifth the a series of publications by the Texas Board of Water Engineers giving chemical analyses of the surface waters in the State of Texas. The samples for which data are given were collected between October 1, 1948 and September 30, 1949. During the water year 25 daily sampling stations were maintained by the Geological Survey. Sampled were collected less frequently during the year at many other points. Quality of water records for previous years can be found in the following reports: "Chemical Composition of Texas Surface Waters, 1938-1945," by W. W. Hastings, and J. H. Rowley; "Chemical Composition of Texas Surface Waters, 1946," by W. W. Hastings and B. Irelan; "Chemical Composition of Texas Surface Waters, 1947," by B. Irelan and J. R. Avrett; "Chemical Composition of Texas Surface Waters, 1948," by B. Irelan, D. E. Weaver, and J. R. Avrett. These reports may be obtained from the Texas Board of Water Engineers and Geological Survey at Austin, Texas. Samples for chemical analysis were collected daily at or near points on streams where gaging stations are maintained for measurement of discharge. Most of the analyses were made of 10-day composites of daily samples collected for a year at each sampling point. Three composite samples were usually prepared each month by mixing together equal quantities of daily samples collected for the 1st to the 10th, from the 11th to the 20th, and during the remainder of the month. Monthly composites were made at a few stations where variation in daily conductance was small. For some streams that are subject to sudden large changes in chemical composition, composite samples were made for shorter periods on the basis of the concentration of dissolved solids as indicated by measurement of specific conductance of the daily samples. The mean discharge for the composite period is reported in second-feet. Specific conductance values are expressed as "micromhos, K x 10 at 25° C." Silica, calcium, magnesium, sodium, potassium, bicarbonate, sulfate, chloride, and nitrate are reported in parts per million. The quantity of dissolved solids is given in tons per acre-foot, tons per day (if discharge records are available), and parts per million. The total and non-carbonate hardness are reported as parts per million calcium carbonate (CaCO3). For those analyses where sodium and potassium are reported separately, "recent sodium" will include the equivalent quantity of sodium only. In analyses where sodium and potassium were calculated and reported as a combined value, the "percent sodium" will include the equivalent quantity of sodium and potassium. Weighted average analyses are given for most daily sampling stations. The weighted average analysis represent approximately the composition of water that would be found in a reservoir containing all the water passing a given station during the year after through mixing in the reservoir. Samples were analyzed according to method regularly used by the Geological Survey. These methods are essentially the same or are modifications of methods described in recognized authoritative publications for mineral analysis of water samples. These quality of water records have been collected as part of the cooperative investigations of the water resources of Texas conducted by the Geological Survey and the Texas Board of Water Engineers. Much of the work would have been impossible without the support of the following Federal State, and local agencies The United States Bureau of Reclamation, U. S. Corps of Engineers, Brazos River Conservation and Reclamation District, Lower Colorado River Authority, Red Bluff Water Power Control District, City of Amarillo, City of Abilene, and City of Forth Worth. The investigations were under the firection of Burdge Irelan, District Chemist, Austin, Texas. Analyses of water samples were made by Clara J. Carter, Lee J. Freeman, Homer D. Smith, Dorothy M. Suttle, DeForrest E. Weaver, and Clarence T. Welborn. Calculations of weighted averages were made by James R. Avrett, Burdge Irelan, Dorothy M. Suttle, and DeFor

Irelan, Burdge

1950-01-01

323

Aluminium content of some processed foods, raw materials and food additives in China by inductively coupled plasma-mass spectrometry.  

PubMed

The level of aluminium in 178 processed food samples from Shenzhen city in China was evaluated using inductively coupled plasma-mass spectrometry. Some processed foods contained a concentration of up to 1226 mg/kg, which is about 12 times the Chinese food standard. To establish the main source in these foods, Al levels in the raw materials were determined. However, aluminium concentrations in raw materials were low (0.10-451.5 mg/kg). Therefore, aluminium levels in food additives used in these foods was determined and it was found that some food additives contained a high concentration of aluminium (0.005-57.4 g/kg). The results suggested that, in the interest of public health, food additives containing high concentrations of aluminium should be replaced by those containing less. This study has provided new information on aluminium levels in Chinese processed foods, raw materials and a selection of food additives. PMID:24786247

Deng, Gui-Fang; Li, Ke; Ma, Jing; Liu, Fen; Dai, Jing-Jing; Li, Hua-Bin

2011-01-01

324

MECHANICS METHODOLOGY FOR TEXTILE PREFORM COMPOSITE MATERIALS  

Microsoft Academic Search

NASA and its contractors have completed a program to develop a basic mechanics underpinning for textile composites. Three major deliverables were produced by the program: 1. a set of test methods for measuring material properties and design allowables 2. mechanics models to predict the effects of the fiber preform architecture and constituent properties on engineering moduli, strength, damage resistance, and

Clarence C. Poe

1996-01-01

325

Chemical production of chondrule oxygen isotopic composition  

NASA Technical Reports Server (NTRS)

Defining the source of observed meteoritic O isotopic anomalies remains a fundamental challenge. The O isotopic composition of chondrules are particularly striking. There are at least three types of chemical processes that produce the isotopic compositions observed in chondrules and Ca-Al-rich inclusions (CAI's). The processes are rather general, viz, they require no specialized processes and the processes associated with chondrule production are likely to produce the observed compositions.

Thiemens, M. H.

1994-01-01

326

Chemical Engineering Journal 149 (2009) 435446 Contents lists available at ScienceDirect  

E-print Network

Chemical Engineering Journal 149 (2009) 435­446 Contents lists available at ScienceDirect Chemical of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, MI- rection, to control the final product quality for a semi-batch reactor [2]. Lou and Huang extended

Huang, Yinlun

327

Future trends in advanced fibers and composite materials technology  

SciTech Connect

By drawing on the wealth of new knowledge in advanced materials, bioscience, and information science, advanced fiber and composite systems are entering a new phase of development. Advances in the understanding of structure/property relationships of materials and related processing technologies have made it possible to tailor-make new material systems, molecule by molecule, to meet specific engineering needs better than metals. The theoretical limits for strength and stiffness of fibers can be predicted based on bond strength and cohesive forces. In the future, fiber technology will continue to advance toward achieving fiber properties closer to theoretical, increasing chemical stability, and developing new product forms tailored for specific engineering needs. The development of tailored high performance fibers and resins systems combined with advances in enabling technologies will provide most efficient solutions to engineering problems. In the future, self-monitoring and self-correcting ``smart`` composite systems will not only sense their structural environment but also respond to prevent structural failures. Just as man-made fibers revolutionized what people wear, man-made composite material systems will revolutionize how people design and build structural material systems.

Dhingra, A.K.; Doherty, T.P. [DuPont, Wilmington, DE (United States)

1993-12-31

328

Profiling the Triacylglyceride Contents in Bat Integumentary Lipids by Preparative Thin Layer Chromatography and MALDI-TOF Mass Spectrometry  

PubMed Central

The mammalian integument includes sebaceous glands that secrete an oily material onto the skin surface. Sebum production is part of the innate immune system that is protective against pathogenic microbes. Abnormal sebum production and chemical composition are also a clinical symptom of specific skin diseases. Sebum contains a complex mixture of lipids, including triacylglycerides, which is species-specific. The broad chemical properties exhibited by diverse lipid classes hinder the specific determination of sebum composition. Analytical techniques for lipids typically require chemical derivatizations that are labor-intensive and increase sample preparation costs. This paper describes how to extract lipids from mammalian integument, separate broad lipid classes by thin-layer chromatography, and profile the triacylglyceride contents using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This robust method enables a direct determination of the triacylglyceride profiles among species and individuals, and it can be readily applied to any taxonomic group of mammals. PMID:24056580

Pannkuk, Evan L.; Risch, Thomas S.; Savary, Brett J.

2013-01-01

329

Profiling the triacylglyceride contents in bat integumentary lipids by preparative thin layer chromatography and MALDI-TOF mass spectrometry.  

PubMed

The mammalian integument includes sebaceous glands that secrete an oily material onto the skin surface. Sebum production is part of the innate immune system that is protective against pathogenic microbes. Abnormal sebum production and chemical composition are also a clinical symptom of specific skin diseases. Sebum contains a complex mixture of lipids, including triacylglycerides, which is species-specific. The broad chemical properties exhibited by diverse lipid classes hinder the specific determination of sebum composition. Analytical techniques for lipids typically require chemical derivatizations that are labor-intensive and increase sample preparation costs. This paper describes how to extract lipids from mammalian integument, separate broad lipid classes by thin-layer chromatography, and profile the triacylglyceride contents using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This robust method enables a direct determination of the triacylglyceride profiles among species and individuals, and it can be readily applied to any taxonomic group of mammals. PMID:24056580

Pannkuk, Evan L; Risch, Thomas S; Savary, Brett J

2013-01-01

330

Analysis of chemical compositions contributable to chemical oxygen demand (COD) of oilfield produced water  

Microsoft Academic Search

This work was to give a comprehensive estimation for the chemical compositions contributable to COD of the produced water treatment system. For this purpose, the wastewater samples were collected from an onshore wastewater treatment plant. The chemical compositions of the wastewater were investigated, and the COD contributed by each component was estimated. The results showed that the COD levels of

Jinren Lu; Xiulin Wang; Baotian Shan; Ximing Li; Weidong Wang

2006-01-01

331

Physical Characterization and Steam Chemical Reactivity of Carbon Fiber Composites  

SciTech Connect

This report documents experiments and analyses that have been done at the Idaho National Engineering and Environmental Laboratory (INEEL) to measure the steam chemical reactivity of two types of carbon fiber composites, NS31 and NB31, proposed for use at the divertor strike points in an ITER-like tokamak. These materials are 3D CFCs constituted by a NOVOLTEX preform and densified by pyrocarbon infiltration and heat treatment. NS31 differs from NB31 in that the final infiltration was done with liquid silicon to reduce the porosity and enhance the thermal conductivity of the CFC. Our approach in this work was twofold: (1) physical characterization measurements of the specimens and (2) measurements of the chemical reactivity of specimens exposed to steam.

Anderl, Robert Andrew; Pawelko, Robert James; Smolik, Galen Richard

2001-05-01

332

Chemically amplified photoresist: Materials and processes  

NASA Astrophysics Data System (ADS)

Advances in microfabrication technology to construct smaller and faster integrated circuits depend on improving resolution capabilities of patterning thin films of photoresist materials by photolithographic imaging. Positive-tone, chemically amplified photoresists represent one of the most important classes of photoresist materials. These materials function by the generation of a photoacid catalyst from the decomposition of a photoacid generator with exposure that catalyzes chemical reactions that alter the development rate of the exposed resist. Chemical amplification is derived from the fact that a single molecule of photogenerated catalyst may participate in numerous reactions. Photoacid catalyzes the cleavage of acid-labile protecting groups from the backbone of the resin polymer, increasing the dissolution rate of the resist in aqueous base. A pattern is formed in the photoresist film from the difference between dissolution rates of the exposed and unexposed material. The continual improvement of the resolution of chemically amplified resists depends on understanding, controlling, and optimizing the chemical processes that govern pattern formation, namely photoacid generation, resin deprotection, and resist dissolution. To elucidate how the formulation of the resist affects these processes, a systematic methodology was designed, validated and implemented to analyze the materials and processing of chemically amplified photoresist systems. The efficiency of photoacid generation and the concentration of photoacid produced upon exposure were determined for a wide range of resist formulations, processing conditions, and exposure technologies. The chemical structure of photoacid generators and base quenchers were found to affect the processes of acid-base neutralization, resin deprotection, and resist development. The reaction-diffusion process of photoacid to deprotect the resin was identified to depend on the concentration of the photoacid generator. A much greater concentration of photoacid was required to render development for ultra-thin films of chemically amplified photoresist less than 150nm thick than for thicker resist films. These investigations identified that the action of photoacid within the resist film is more complex than previously thought, and provided insight for the design and optimization of photoresist materials and processes.

Pawloski, Adam Richard

2002-01-01

333

Journal of Composite Materials, July 2006, Vol. 40 no. 13, 1163-1174 1163 Thermal Expansion of Aluminum/Fly Ash Cenosphere Composites Synthesized by  

E-print Network

of Aluminum/Fly Ash Cenosphere Composites Synthesized by Pressure Infiltration Technique P.K. Rohatgi1 , N 125 m average size hollow fly ash particles (cenospheres) were measured using a dilatometer. Three of the fly ash cenospheres in the composites were around 65%. The CTE of the composites was measured

Gupta, Nikhil

334

Globally convergent computation of chemical equilibrium composition.  

PubMed

We report the Newton-Raphson based globally convergent computational method for determination of chemical equilibrium composition. In the computation of chemical equilibrium composition, an appearance of nonpositive value of number of moles of any component leads to discrepancy. The process of conditional backtracking and adaptive set of refining factors for Newton-Raphson steps are employed to resolve the problem. The mathematical formulation proposed by Heuze et al. (J Chem Phys 1985, 83, 4734) has been solved using proposed computational method, instead of empirical iterative formulation, as proposed by them. Results for the same numerical example, used by Heuze et al. (J Chem Phys 1985, 83, 4734) and White et al. (J Chem Phys 1958, 28, 751) are presented in addition to decomposition of Cyclotrimethylenetrinitramine for fixed temperature and pressure. It is observed that the proposed method is efficient and globally convergent. An even noteworthy finding is that the set of refining factors can be chosen from the range 0.1 to eta, where eta may be greater than one depending on how smoothly system of nonlinear equations is dependant on corresponding variable. Related analysis and results are discussed. PMID:18161685

Patil, Sunil; Aiyer, R C; Sharma, K C

2008-05-01

335

Pyrolysis of municipal plastic wastes II: Influence of raw material composition under catalytic conditions  

SciTech Connect

Highlights: > ZSM-5 zeolite catalytic pyrolysis transforms municipal plastic waste into liquids and gases useful as fuels or source of chemicals. > The composition of the waste sample plays an important role on the catalyst activity and the products obtained. > ZSM-5 zeolite is somehow deactivated when high proportions of fine inorganic materials are present in the sample. > When the sample contains cellulose-based materials, the formation of a two-phase liquid fraction can be avoided by a low temperature step. - Abstract: In this work, the results obtained in catalytic pyrolysis of three plastic waste streams which are the rejects of an industrial packing wastes sorting plant are presented. The samples have been pyrolysed in a 3.5 dm{sup 3} reactor under semi-batch conditions at 440 {sup o}C for 30 min in nitrogen atmosphere. Commercial ZSM-5 zeolite has been used as catalyst in liquid phase contact. In every case, high HHV gases and liquids which can be useful as fuels or source of chemicals are obtained. A solid fraction composed of the inorganic material contained in the raw materials and some char formed in the pyrolysis process is also obtained. The zeolite has shown to be very effective to produce liquids with great aromatics content and C3-C4 fraction rich gases, even though the raw material was mainly composed of polyolefins. The characteristics of the pyrolysis products as well as the effect of the catalyst vary depending on the composition of the raw material. When paper rich samples are pyrolysed, ZSM-5 zeolite increases water production and reduces CO and CO{sub 2} generation. If stepwise pyrolysis is applied to such sample, the aqueous liquid phase can be separated from the organic liquid fraction in a first low temperature step.

Lopez, A., E-mail: alex.lopez@ehu.es [Chemical and Environmental Engineering Department, School of Engineering of Bilbao, Alda. Urquijo s/n, 48013 Bilbao (Spain); Marco, I. de; Caballero, B.M.; Laresgoiti, M.F.; Adrados, A.; Torres, A. [Chemical and Environmental Engineering Department, School of Engineering of Bilbao, Alda. Urquijo s/n, 48013 Bilbao (Spain)

2011-09-15

336

Strain rate behavior of composite materials  

Microsoft Academic Search

The effect of strain rate on the compressive and shear behavior of carbon\\/epoxy composite materials was investigated. Strain rate behavior of composites with fiber waviness was also studied. Falling weight impact system and servohydraulic testing machine were used for dynamic characterisation of composite materials in compression at strain rates up to several hundred per second. Strain rates below 10s?1 were

H. M. Hsiao; I. M. Daniel

1998-01-01

337

Nano composite phase change materials microcapsules  

NASA Astrophysics Data System (ADS)

MicroPCMs with nano composite structures (NC-MicroPCMs) have been systematically studied. NC-MicroPCMs were fabricated by the in situ polymerization and addition of silver NPs into core-shell structures. A full factorial experiment was designed, including three factors of core/shell, molar ratio of formaldehyde/melamine and NPs addition. 12 MicroPCMs samples were prepared. The encapsulated efficiency is approximately 80% to 90%. The structural/morphological features of the NC-MicroPCMs were evaluated. The size was in a range of 3.4 mu m to 4.0 mu m. The coarse appearance is attributed to NPs and NPs are distributed on the surface, within the shell and core. The NC-MicroPCMs contain new chemical components and molecular groups, due to the formation of chemical bonds after the pretreatment of NPs. Extra X-ray diffraction peaks of silver were found indicating silver nano-particles were formed into an integral structure with the core/shell structure by means of chemical bonds and physical linkages. Extra functionalities were found, including: (1) enhancement of IR radiation properties; (2) depression of super-cooling, and (3) increase of thermal stabilities. The effects of SERS (Surface Enhanced Raman Spectroscopy) arising from the silver nano-particles were observed. The Raman scattering intensity was magnified more than 100 times. These effects were also exhibited in macroscopic level in the fabric coatings as enhanced IR radiation properties were detected by the "Fabric Infrared Radiation Management Tester" (FRMT). "Degree of Crystallinity" (DOC) was measured and found the three factors have a strong influence on it. DOC is closely related to thermal stability and MicroPCMs with a higher DOC show better temperature resistance. The thermal regulating effects of the MicroPCMs coatings were studied. A "plateau regions" was detected around the temperature of phase change, showing the function of PCMs. Addition of silver nano-particles to the MicroPCMs has a positive influence on it. NC-MicroPCMs with introducing silver nano particles into the MicroPCMs structure, have shown excellent multifunctional thermal properties and thermal stabilities that are far beyond those of the conventional MicroPCMs. The novel NC-MicroPCMs can be used to develop advanced smart materials and products with prosperous and promising applications in a number of industries.

Song, Qingwen

338

Quantitative measurement of nanomechanical properties in composite materials  

NASA Astrophysics Data System (ADS)

In this work, quantitative Atomic force acoustic microscopy (AFAM) was used to measure nanomechanical properties and to determine microstructural morphology in fiber reinforced composites and hard calcified tissue. In carbon fiber reinforced composites, the fiber-matrix interphase is of interest as it affects the primary load-transfer process and thereby bulk mechanical properties of reinforced composites. The study of properties in the interphase region is important for an understanding of the bulk mechanical properties, which have been shown affected by moisture-based environmental degradation. Single point AFAM testing has been used to quantitatively determine elastic properties at the fiber-matrix interphase by taking advantage of the high spatial scanning resolution capable of measuring interphase dimensions. Carbon-fiber epoxy composite samples were degraded in laboratory conditions by exposure to a accelerated hydrothermal degradation environment in deionized water and salt water. Composite degradation has been characterized by the change in the epoxy matrix contact stiffness and the interphase properties. A decrease in matrix stiffness was found to coincide with the environmental exposure and moisture absorption of the samples. Interphase stiffness measurements indicate a constant interphase thickness as a function of environmental exposure. Chemical analysis of the epoxy using FTIR and Raman spectroscopy indicate hydrolysis of the C-O-C and Epoxide bonds which contribute to the decrease in epoxy mechanical properties. Accelerated degradation by salt water and deionized water both resulted in degradation of the epoxy, though the presence of sodium chloride showed less degradation. From SEM, debonding of the fiber-matrix interface was observed to be more severe when exposed to a salt water environment. In performing quantitative AFAM measurements, the effects of tip shape on the contact mechanics at the epoxy interface were found to influence the reported results significantly, and new, power-law body of revolution models of the probe tip geometry have been applied. Due to the low yield strength of polymers compared with other engineering materials, elastic-plastic contact is considered to better represent the epoxy surface response and was used to acquire more accurate quantitative measurements. Visco-elastic contact response was introduced in the boundary condition of the AFAM cantilever vibration model, due to the creep nature of epoxy, to determine time-dependent effects. These methods have direct impact on the quantitative measurement capabilities of near-filler interphase regions in polymers and composites and the long-term influence of environmental conditions on composites. In addition, quantitative AFAM scans were made on distal surfaces of human bicuspids and molars, to determine the microstructural and spatial variation in nanomechanical properties of the enamel biocomposite. Single point AFAM measurements were performed on individual enamel prism and sheath locations to determine spatial elastic modulus. Mechanical property variation of enamel is associated to the differences in the mineral to organic content and the apatite crystal orientations within the enamel microstructure. Also, variation in the elastic modulus of the enamel ultrastructure was observed in measurements at the outer enamel versus near the dentine enamel junction (DEJ).

Zhao, Wei

339

Polyolefin composites containing a phase change material  

DOEpatents

A composite useful in thermal energy storage, said composite being formed of a polyolefin matrix having a phase change material such as a crystalline alkyl hydrocarbon incorporated therein, said polyolefin being thermally form stable; the composite is useful in forming pellets, sheets or fibers having thermal energy storage characteristics; methods for forming the composite are also disclosed.

Salyer, Ival O. (Dayton, OH)

1991-01-01

340

Chemical compositions responsible for inflammation and tissue damage in the mouse lung by coarse and fine particulate samples from contrasting air pollution in Europe  

SciTech Connect

Inflammation is regarded as an important mechanism in mortality and morbidity associated with exposures of cardiorespiratory patients to urban air particulate matter. We investigated the association of the chemical composition and sources of urban air fine (PM2.5-0.2) and coarse (PM10-2.5) particulate samples with the inflammatory activity in the mouse lung. The particulate samples were collected during selected seasons in six European cities using a high-volume cascade impactor. Healthy C57BL/6J mice were intratracheally instilled with a single dose (10 mg/kg) of the particulate samples. At 4, 12, and 24 h after the exposure, the lungs were lavaged and the bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation and tissue damage: cell number, total protein, and cytokines (tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and KC). Dicarboxylic acids and transition metals, especially Ni and V, in PM2.5-0.2 correlated positively and some secondary inorganic ions (NO{sub 3}{sup -}, NH{sub 4}{sup +}) negatively with the inflammatory activity. Total organic matter and SO{sub 4}{sup 2-} had no consistent correlations. In addition, the soil-derived constituents (Ca{sup 2+}, Al, Fe, Si) showed positive correlations with the PM2.5-0.2-induced inflammatory activity, but their role in PM10 (2.5) remained obscure, possibly due to largely undefined biogenic material. Markers of poor biomass and coal combustion, i.e., monosaccharide anhydrides and As, were associated with elevated PAH contents in PM2.5 (0.2) and a consistent immunosuppressive effect. Overall, our results support epidemiological findings that the local sources of incomplete combustion and resuspended road dust are important in urban air particulate pollution-related health effects.

Happo, M.S.; Hirvonen, M.R.; Halinen, A.I.; Jalava, P.I.; Pennanen, A.S.; Sillanpaa, M.; Hillamo, R.; Salonen, R.O. [National Public Health Institute, Kuopio (Finland). Dept. of Environmental Health

2008-07-01

341

Thin film dielectric composite materials  

DOEpatents

A dielectric composite material comprising at least two crystal phases of different components with TiO.sub.2 as a first component and a material selected from the group consisting of Ba.sub.1-x Sr.sub.x TiO.sub.3 where x is from 0.3 to 0.7, Pb.sub.1-x Ca.sub.x TiO.sub.3 where x is from 0.4 to 0.7, Sr.sub.1-x Pb.sub.x TiO.sub.3 where x is from 0.2 to 0.4, Ba.sub.1-x Cd.sub.x TiO.sub.3 where x is from 0.02 to 0.1, BaTi.sub.1-x Zr.sub.x O.sub.3 where x is from 0.2 to 0.3, BaTi.sub.1-x Sn.sub.x O.sub.3 where x is from 0.15 to 0.3, BaTi.sub.1-x Hf.sub.x O.sub.3 where x is from 0.24 to 0.3, Pb.sub.1-1.3x La.sub.x TiO.sub.3+0.2x where x is from 0.23 to 0.3, (BaTiO.sub.3).sub.x (PbFeo.sub.0.5 Nb.sub.0.5 O.sub.3).sub.1-x where x is from 0.75 to 0.9, (PbTiO.sub.3).sub.- (PbCo.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.1 to 0.45, (PbTiO.sub.3).sub.x (PbMg.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.2 to 0.4, and (PbTiO.sub.3).sub.x (PbFe.sub.0.5 Ta.sub.0.5 O.sub.3).sub.1-x where x is from 0 to 0.2, as the second component is described. The dielectric composite material can be formed as a thin film upon suitable substrates.

Jia, Quanxi (Los Alamos, NM); Gibbons, Brady J. (Los Alamos, NM); Findikoglu, Alp T. (Los Alamos, NM); Park, Bae Ho (Los Alamos, NM)

2002-01-01

342

The determination of the chemical composition profile of the GaAs/AlGaAs heterostructures designed for quantum cascade lasers by means of synchrotron radiation  

NASA Astrophysics Data System (ADS)

The chemical composition profile of the GaAs/AlGaAs quantum cascade structures grown on (0 0 1) GaAs substrate by molecular beam epitaxy is studied by a synchrotron radiation high-resolution X-ray diffraction. The analysis is carried out for the whole structure as well for its parts. In order to determine some structural parameters, such as: the thickness and chemical composition of each layer making up the investigated structure, the profile of the interface between succeeding layers, and the preservation of the structure periodicity, the experimental X-ray diffraction profiles are compared with simulated ones calculated by means of Darwin dynamical theory of X-ray diffraction. It is shown that this method gives correct chemical composition profiles and allows for the evaluation of the deviations from the designed values of the structural parameters in most investigated cases. Limits of the method are discussed, especially by the determination of the chemical composition profile for thin heterostructures, such as those making active or injector regions.

Gaca, Jaros?aw; Wójcik, Marek; Bugajski, Maciej; Kosiel, Kamil

2011-10-01

343

Faecal near infrared reflectance spectroscopy (NIRS) to assess chemical composition, in vivo digestibility and intake of tropical grass by Creole cattle  

Microsoft Academic Search

Selective grazing by ruminant livestock and other herbivores causes difficulties in measuring or estimating the chemical composition and functional properties (digestibility and intake) of the diets of free grazers. New methodologies using faecal near infrared reflection spectroscopy (NIRS) offers scope to estimate diet quality in grazing animals once suitable calibration equations have been developed. This study was conducted to determine

M Boval; D. B Coates; P Lecomte; V Decruyenaere; H Archimède

2004-01-01

344

Ferromanganese nodules from MANOP Sites H, S, and R-Control of mineralogical and chemical composition by multiple accretionary processes  

USGS Publications Warehouse

The chemical composition of ferromanganese nodules from the three nodule-bearing MANOP sites in the Pacific can be accounted for in a qualitative way by variable contributions of distinct accretionary processes. These accretionary modes are: 1. (1) hydrogenous, i.e., direct precipitation or accumulation of colloidal metal oxides in seawater, 2. (2) oxic diagenesis which refers to a variety of ferromanganese accretion processes occurring in oxic sediments; and 3. (3) suboxic diagenesis which results from reduction of Mn+4 by oxidation of organic matter in the sediments. Geochemical evidence suggests processes (1) and (2) occur at all three MANOP nodule-bearing sites, and process (3) occurs only at the hemipelagic site, H, which underlies the relatively productive waters of the eastern tropical Pacific. A normative model quantitatively accounts for the variability observed in nearly all elements. Zn and Na, however, are not well explained by the three end-member model, and we suggest that an additional accretionary process results in greater variability in the abundances of these elements. Variable contributions from the three accretionary processes result in distinct top-bottom compositional differences at the three sites. Nodule tops from H are enriched in Ni, Cu, and Zn, instead of the more typical enrichments of these elements in nodule bottoms. In addition, elemental correlations typical of most pelagic nodules are reversed at site H. The three accretionary processes result in distinct mineralogies. Hydrogenous precipitation produces ??MnO2. Oxic diagenesis, however, produces Cu-Ni-rich todorokite, and suboxic diagenesis results in an unstable todorokite which transforms to a 7 A?? phase ("birnessite") upon dehydration. The presence of Cu and Ni as charge-balancing cations influence the stability of the todorokite structure. In the bottoms of H nodules, which accrete dominantly by suboxic diagenesis, Na+ and possibly Mn+2 provide much of the charge balance for the todorokite structure. Limited growth rate data for H nodules suggest suboxic accretion is the fastest of the three processes, with rates at least 200 mm/106 yr. Oxic accretion is probably 10 times slower and hydrogenous 100 times slower. Since these rates predict more suboxic component in bulk nodules than is calculated by the normative analysis, we propose that suboxic accretion is a non-steady-state process. Variations in surface water productivity cause pulses of particulate flux to the sea floor which result in transient Mn reduction in the surface sediments and reprecipitation on nodule surfaces. ?? 1984.

Dymond, J.; Lyle, M.; Finney, B.; Piper, D.Z.; Murphy, K.; Conard, R.; Pisias, N.

1984-01-01

345

Development of composite materials by mechanochemical treatment of post-consumer plastic waste  

Microsoft Academic Search

Improvement of mechanical properties of recycled mixed plastic waste is one of the fundamental goals in any recycling process. However, polymer immiscibility makes the development of any effective reprocessing method difficult. In this work, a polymer milling process with liquid CO2 was applied to polymeric mixed waste, obtaining a powder material which was successfully utilized as a matrix for a

F Cavalieri; F Padella

2002-01-01

346

Chemical composition and starch digestibility in flours from Polish processed legume seeds.  

PubMed

The study was undertaken to determine the effect of various treatments, i.e. cooking after soaking, freezing after cooking and storage at a low temperature (-18°C, 21days), and autoclaving, of Polish cultivars of bean, pea and lentil seeds on the chemical composition and starch digestibility of the resultant flours. The cooking of seeds caused a significant decrease in contents of ash (by 11-48%), polyphenols (by 10-70%) and protein (to 19%) in flours made of bean. In addition, analyses demonstrated significantly decreased contents of resistant starch, RS (by 61-71%) and slowly digestible starch, SDS (by 56-84%). Storage of frozen seeds resulted in insignificant changes in the chemical composition, and in increased contents of both RS and SDS. The flours produced upon the autoclaving process were characterized by similar changes in the contents of ash and protein as in cooked seeds, yet losses of polyphenols were lower and, simultaneously, contents of RS and SDS were higher. All the analyzed flours were shown to be characterized by a reduced content of amylose in starch, which might have affected its digestibility. This was indicated by a strict negative correlation reported between the value of the starch digestion index (SDRI) and amylose content of starch (r=0.84, p>0.05). PMID:22953824

Piecyk, Ma?gorzata; Wo?osiak, Rafa?; Dru?ynska, Beata; Worobiej, Elwira

2012-12-01

347

Chemical composition and temperature dependent performance of ZnO-thin film transistors deposited by pulsed and continuous spray pyrolysis  

SciTech Connect

Zinc oxide thin film transistors (TFTs) deposited by continuous and pulsed spray pyrolysis were investigated to analyze process kinetics which make reduction of process temperature possible. Thus, fluid mechanics, chemical composition, electrical performance, and deposition and annealing temperature were systematically analyzed. It was found that ZnO layers continuously deposited at 360?°C contained zinc oxynitrides, CO{sub 3}, and hydro carbonate groups from pyrolysis of basic zinc acetate. Statistically, every second wurtzite ZnO unit cell contained an impurity atom. The purity and performance of the ZnO-TFTs increased systematically with increasing deposition temperature due to an improved oxidation processes. At 500?°C the zinc to oxygen ratio exceeded a high value of 0.96. Additionally, the ZnO film was not found to be in a stabilized state after deposition even at high temperatures. Introducing additional subsequent annealing steps stabilizes the film and allows the reduction of the overall thermal stress to the substrate. Further improvement of device characteristics was obtained by pulsed deposition which allowed a more effective transport of the by-products and oxygen. A significant reduction of the deposition temperature by 140?°C was achieved compared to the same performance as in continuous deposition mode. The trap density close to the Fermi energy could be reduced by a factor of two to 4?×?10{sup 17}?eV{sup ?1}?cm{sup ?3} due to the optimized combustion process on the surface. The optimization of the deposition processes made the fabrication of TFTs with excellent performance possible. The mobility was high and exceeded 12 cm{sup 2}/V s, the subthreshold slope was 0.3 V dec{sup ?1}, and an on-set close to the ideal value of 0?V was achieved.

Ortel, Marlis; Balster, Torsten; Wagner, Veit [School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany)

2013-12-21

348

Chemical composition and temperature dependent performance of ZnO-thin film transistors deposited by pulsed and continuous spray pyrolysis  

NASA Astrophysics Data System (ADS)

Zinc oxide thin film transistors (TFTs) deposited by continuous and pulsed spray pyrolysis were investigated to analyze process kinetics which make reduction of process temperature possible. Thus, fluid mechanics, chemical composition, electrical performance, and deposition and annealing temperature were systematically analyzed. It was found that ZnO layers continuously deposited at 360 °C contained zinc oxynitrides, CO3, and hydro carbonate groups from pyrolysis of basic zinc acetate. Statistically, every second wurtzite ZnO unit cell contained an impurity atom. The purity and performance of the ZnO-TFTs increased systematically with increasing deposition temperature due to an improved oxidation processes. At 500 °C the zinc to oxygen ratio exceeded a high value of 0.96. Additionally, the ZnO film was not found to be in a stabilized state after deposition even at high temperatures. Introducing additional subsequent annealing steps stabilizes the film and allows the reduction of the overall thermal stress to the substrate. Further improvement of device characteristics was obtained by pulsed deposition which allowed a more effective transport of the by-products and oxygen. A significant reduction of the deposition temperature by 140 °C was achieved compared to the same performance as in continuous deposition mode. The trap density close to the Fermi energy could be reduced by a factor of two to 4 × 1017 eV-1 cm-3 due to the optimized combustion process on the surface. The optimization of the deposition processes made the fabrication of TFTs with excellent performance possible. The mobility was high and exceeded 12 cm2/V s, the subthreshold slope was 0.3 V dec-1, and an on-set close to the ideal value of 0 V was achieved.

Ortel, Marlis; Balster, Torsten; Wagner, Veit

2013-12-01

349

Comparative Analysis of the Chemical Composition of Mixed and Pure Cultures of Green Algae and Their Decomposed Residues by 13C Nuclear Magnetic Resonance Spectroscopy  

PubMed Central

It is known that macromolecular organic matter in aquatic environments, i.e., humic substances, is highly aliphatic. These aliphatic macromolecules, predominantly paraffinic in structure, are prevalent in marine and lacustrine sediments and are believed to originate from algae or bacteria. A comparative study of mixed and pure cultures of green algae and their decomposed residues was performed by using solid-state 13C nuclear magnetic resonance spectroscopy as the primary analytical method. Results obtained in this study confirm the presence of components that are chemically refractory and that are defined as alghumin and hydrolyzed alghumin. These were detected in heterogeneous, homogeneous, and axenic biomasses composed of several genera of Chlorophyta. Although the chemical composition of algal biomass varied with culture conditions, the chemical structure of the alghumin and hydrolyzed alghumin, demonstrated by 13C nuclear magnetic resonance spectroscopy appeared to be constant for members of the Chlorophyta examined in this study. The alghumin was dominated by carbohydrate-carbon, with minor amounts of amide or carboxyl carbon and paraffinic carbon, the latter surviving strong hydrolysis by 6 N HCI (hydrolyzed alghumin). Bacterial decomposition of heterogeneous algal biomass labeled with 13C was conducted under both aerobic and anaerobic conditions to determine chemical structure and stability of the refractory material. The refractory fraction ranged from 33% in aerobic to 44% in anaerobic cultures. The refractory fraction recovered from either aerobic or anaerobic degradation comprised 40% alghumin, which represented an enrichment by 10% relative to the proportion of alghumin derived from whole cells of algae. The paraffinic component in the hydrolyzed alghumin of whole algal cells was found to be 1.8% and increased to 5.1 and 6.9% after aerobic and anaerobic bacterial degradation, respectively. It is concluded that members of the Chlorophyta contain a common insoluble structure composed of paraffinic carbon that is resistant to chemical and bacterial degradation under conditions used in this study. The paraffinic structure is identical to those constituting humin of aquatic origin. Thus, alga-derived macromolecular compounds deposited in aquatic environments (alghumin) probably contribute to sedimentary humic substances. PMID:16347601

Zelibor, J. L.; Romankiw, L.; Hatcher, P. G.; Colwell, R. R.

1988-01-01

350

Comparative analysis of the chemical composition of mixed and pure cultures of green algae and their decomposed residues by C nuclear magnetic resonance spectroscopy.  

PubMed

It is known that macromolecular organic matter in aquatic environments, i.e., humic substances, is highly aliphatic. These aliphatic macromolecules, predominantly paraffinic in structure, are prevalent in marine and lacustrine sediments and are believed to originate from algae or bacteria. A comparative study of mixed and pure cultures of green algae and their decomposed residues was performed by using solid-state C nuclear magnetic resonance spectroscopy as the primary analytical method. Results obtained in this study confirm the presence of components that are chemically refractory and that are defined as alghumin and hydrolyzed alghumin. These were detected in heterogeneous, homogeneous, and axenic biomasses composed of several genera of Chlorophyta. Although the chemical composition of algal biomass varied with culture conditions, the chemical structure of the alghumin and hydrolyzed alghumin, demonstrated by C nuclear magnetic resonance spectroscopy appeared to be constant for members of the Chlorophyta examined in this study. The alghumin was dominated by carbohydrate-carbon, with minor amounts of amide or carboxyl carbon and paraffinic carbon, the latter surviving strong hydrolysis by 6 N HCI (hydrolyzed alghumin). Bacterial decomposition of heterogeneous algal biomass labeled with C was conducted under both aerobic and anaerobic conditions to determine chemical structure and stability of the refractory material. The refractory fraction ranged from 33% in aerobic to 44% in anaerobic cultures. The refractory fraction recovered from either aerobic or anaerobic degradation comprised 40% alghumin, which represented an enrichment by 10% relative to the proportion of alghumin derived from whole cells of algae. The paraffinic component in the hydrolyzed alghumin of whole algal cells was found to be 1.8% and increased to 5.1 and 6.9% after aerobic and anaerobic bacterial degradation, respectively. It is concluded that members of the Chlorophyta contain a common insoluble structure composed of paraffinic carbon that is resistant to chemical and bacterial degradation under conditions used in this study. The paraffinic structure is identical to those constituting humin of aquatic origin. Thus, alga-derived macromolecular compounds deposited in aquatic environments (alghumin) probably contribute to sedimentary humic substances. PMID:16347601

Zelibor, J L; Romankiw, L; Hatcher, P G; Colwell, R R

1988-04-01

351

Lactic acid fermentation by cells immobilised on various porous cellulosic materials and their alginate/poly-lactic acid composites.  

PubMed

Porous delignified cellulose (or tubular cellulose, abbr. TC) from Indian Mango (Mangifera indica) and Sal (Shorea robusta) wood and Rice husk, and TC/Ca-alginate/polylactic acid composites, were used as Lactobacillus bulgaricus immobilisation carriers leading to improvements in lactic acid fermentation of cheese whey and synthetic lactose media, compared to free cells. Specifically, shorter fermentation rates, higher lactic acid yields (g/g sugar utilised) and productivities (g/Ld), and higher amounts of volatile by-products were achieved, while no significant differences were observed on the performance of the different immobilised biocatalysts. The proposed biocatalysts are of food grade purity, cheap and easy to prepare, and they are attractive for bioprocess development based on immobilised cells. Such composite biocatalysts may be used for the co-immobilisation of different microorganisms or enzymes (in separate layers of the biocatalyst), to efficiently conduct different types of fermentations in the same bioreactor, avoiding inhibition problems of chemical or biological (competition) nature. PMID:24690466

Kumar, Mrinal Nishant; Gialleli, Angelika-Ioanna; Masson, Jean Bernard; Kandylis, Panagiotis; Bekatorou, Argyro; Koutinas, Athanasios A; Kanellaki, Maria

2014-08-01

352

Fabrication of Nanostructured Wc-Based Hard Materials with Different Contents of co by High Frequency Induction Heated Sintering  

Microsoft Academic Search

Hard materials, in particular tungsten carbide (WC) hard material has been used in many industries as cutting tool and abrasive materials. For improving toughness, binders are added into carbide materials. The effect of Co as binder on the mechanical properties in the nanosized WC was discussed. The hardness and fracture toughness were also investigated using 30 kgf load Vickers indenter.

Duck-Soo Kang; Kee-Do Woo; Eui-Pyo Kwon; Sang-Hyuk Kim; Min-Seok Moon; In-Jin Shon

2010-01-01

353

Optical absorption measurements in a new composite material by combined photoacoustic and beam transmission techniques  

NASA Astrophysics Data System (ADS)

The absorption coefficient of a highly absorbing (?>105 cm-1) new composite produced in our laboratory, namely manganese dioxide surface-impregnated polyethylene (MnO2-PE) film, has been measured in the visible range. We have employed a combination of concurrently taken photoacoustic and beam transmission data. This combination proved to be an effective means for the optical evaluation of highly absorptive samples which dispenses with the need for prior knowledge of the sample reflectivity. Theoretical interpretation of MnO2-PE absorption profile, with due account of the processes underlining the photoacoustic signal generation, reveals a semiconductor behavior with an estimated effective gap wavelength of 8050 Å. Technical implications of the availability of these highly absorptive flexible films are briefly considered.

Cesar, C. L.; Lima, C. A. S.; Leite, N. F.; Vargas, H.; Rubira, A. F.; Galembeck, F.

1985-05-01

354

Titan's Interior Chemical Composition: Possible Important Phase Transitions  

NASA Astrophysics Data System (ADS)

We study the interior composition of Titan using thermal chemical equilibrium calculations that are valid to high pressures and temperatures. The equations of state are based on exponential-6 fluid theory and have been validated against experimental data up to a few Mbars in pressure and approximately 20000K in temperature. In addition to CHNO molecules, we account for multi-phases of carbon, water and a variety of metals such as Al and Fe, and their oxides. With these fluid equations of state, chemical equilibrium is calculated for a set of product species. As the temperature and pressure evolves for increasing depth in the interior, the chemical equilibrium shifts. We assume that Titan is initially composed of comet material, which we assume to be solar, except for hydrogen, which we take to be depleted by a factor 1/1000. We find that a significant amount of nitrogen is in the form of N2, rather than NH3. Moreover, above 12 kbars pressure, as is the interior pressure of Titan, a significant amount of the carbon is in the form of graphite, rather than CO2 and CH4. We discuss the implications of these results for understanding the atmospheric and surface composition of Titan. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Howard, Michael; Fried, L. E.; Khare, B. N.; McKay, C. P.

2008-09-01

355

Towards optimization of crack resistance of composite materials by adjustment of fiber shapes  

Microsoft Academic Search

We investigate the evolution and propagation of cracks in 2-d elastic domains, which are subjected to quasi-static loading scenarios. In addition to the classical variational formulation, where the standard potential energy is minimized over the cracked domain under physical conditions characterizing the behavior of the material close to the crack (e.g. non-penetration conditions), we include a ‘cohesive traction term’ in

M. Prechtel; G. Leugering; P. Steinmann; M. Stingl

2011-01-01

356

A fatigue damage model of composite materials  

Microsoft Academic Search

The mechanical properties of composite materials degrade progressively with the increasing of the number of cyclic loadings. Based on the stiffness degradation rule of composites, a phenomenological fatigue damage model is presented in this paper, which contains two material parameters. They are proportional to the fatigue life of materials and inversely proportional to the fatigue loading level. Thirteen sets of

Fuqiang Wu; WeiXing Yao

2010-01-01

357

[Studies on change of chemical composition in coptis-scute herb couple by using HPCE and HPLC].  

PubMed

Quantitative analysis on different proportions of couple of Coptis and Scute. The proportions of Coptis and Scute couple were 6:1, 6:4, 6:7, 6:10, 6:13, separately. The contents of alkaloids in Coptis and decoction of Coptis and Scute were determined by HPCE and the contents of flavones in Scute and decoction of Coptis and Scute were determined by HPLC, separately. Precipitates were generated after the couple of Coptis and Scute, which results the decrease of contents of effective ingredients. PMID:18507348

Li, Wei; Song, Feng-Rui; Liu, Zhi-Qiang; Liu, Shu-Ying

2008-02-01

358

Subscriber access provided by DUKE UNIV Chemistry of Materials is published by the American Chemical Society. 1155 Sixteenth  

E-print Network

27708 Yongqian Wang and Zhong Lin Wang School of Materials Science and Engineering, Georgia Institute Received December 19, 2000 Uniform iron-molybdenum nanoparticles were prepared by thermal decomposition/amine of the protective agents on the sizes of the produced nanoparticles were systematically studied. The prepared nano

Liu, Jie

359

Color masterbatch resin composition for packaging material for photographic photosensitive material and packaging material  

US Patent & Trademark Office Database

A color masterbach resin composition for a packaging material for a photographic photosensitive material which does not adversely affect photographic properties of the photographic photosensitive material, comprising a light-shielding material in a concentration thrice as much as or more that of the packaging material for a photographic photosensitive material, and a thermoplastic resin of which 50 wt. % or more is the same type as a thermoplastic resin occupying 50 wt. % or more of the total thermoplastic resin composing the packaging material for a photographic photosensitive material, production thereof, a packaging material for a photographic photosensitive material formed of a color masterbatch resin composition, and production thereof. In the color masterbatch resin composition and the packaging material for a photographic photosensitive material of the invention, light-shielding material is dispersed uniformly by employing a special resin composition, and thereby, adverse affects upon photographic hpotosensitive materials are prevented, and favorable appearance can be ensured. Moreover, fog with time, abnormal sensitivity, abrasion, pressure marks, etc. can be prevented.

1998-09-29

360

Method for machining holes in composite materials  

NASA Technical Reports Server (NTRS)

A method for boring well defined holes in a composite material such as graphite/epoxy is discussed. A slurry of silicon carbide powder and water is projected onto a work area of the composite material in which a hole is to be bored with a conventional drill bit. The silicon carbide powder and water slurry allow the drill bit, while experiencing only normal wear, to bore smooth, cylindrical holes in the composite material.

Daniels, Julia G. (inventor); Ledbetter, Frank E., III (inventor); Clemons, Johnny M. (inventor); Penn, Benjamin G. (inventor); White, William T. (inventor)

1987-01-01

361

Smart materials: strain sensing and stress determination by means of nanotube sensing systems, composites, and devices  

NASA Technical Reports Server (NTRS)

The present invention is directed toward devices comprising carbon nanotubes that are capable of detecting displacement, impact, stress, and/or strain in materials, methods of making such devices, methods for sensing/detecting/monitoring displacement, impact, stress, and/or strain via carbon nanotubes, and various applications for such methods and devices. The devices and methods of the present invention all rely on mechanically-induced electronic perturbations within the carbon nanotubes to detect and quantify such stress/strain. Such detection and quantification can rely on techniques which include, but are not limited to, electrical conductivity/conductance and/or resistivity/resistance detection/measurements, thermal conductivity detection/measurements, electroluminescence detection/measurements, photoluminescence detection/measurements, and combinations thereof. All such techniques rely on an understanding of how such properties change in response to mechanical stress and/or strain.

Barrera, Enrique V. (Inventor); Nagarajaiah, Satish (Inventor); Dharap, Prasad (Inventor); Zhiling, Li (Inventor); Kim, Jong Dae (Inventor)

2010-01-01

362

Elaboration of antibiofilm materials by chemical grafting of an antimicrobial peptide  

Microsoft Academic Search

A peptide antibiotic, gramicidin A, was covalently bound to cystamine self-assembled monolayers on gold surfaces. Each step\\u000a of the surface functionalization was characterized by polarization modulation infrared reflection absorption spectroscopy\\u000a and X-ray photoelectron spectroscopy. The antimicrobial activity of the anchored gramicidin was tested against three Gram-positive\\u000a bacteria (Listeria ivanovii, Enterococcus faecalis, and Staphylococcus aureus), the Gram-negative bacterium Escherichia coli and

Jean-Fabrice Yala; Pascal Thebault; Arnaud Héquet; Vincent Humblot; Claire-Marie Pradier; Jean-Marc Berjeaud

2011-01-01

363

Morphology and microstructure of composite materials  

NASA Technical Reports Server (NTRS)

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

Tiwari, S. N.; Srinivansan, K.

1991-01-01

364

Microbially mediated CH 4 consumption and N 2 O emission is affected by elevated CO 2 , soil water content, and composition of semi-arid grassland species  

Microsoft Academic Search

Elevated CO2 affects plant productivity, but also water availability and plant species composition in semi-arid grasslands, thereby potentially\\u000a causing complex effects on CH4 consumption and N2O emission. We studied the effects of atmospheric CO2 concentration (400 vs 780 ?L L?1), water content (15 vs 20% gravimetric soil moisture), and composition of semi-arid grassland species (perennial grasses\\u000a Bouteloua gracilis, Hesperostipa comata, and

Feike A. Dijkstra; Jack A. Morgan; Daniel R. LeCain; Ronald F. Follett

2010-01-01

365

Alkali metal protective garment and composite material  

DOEpatents

A protective garment and composite material providing satisfactory heat resistance and physical protection for articles and personnel exposed to hot molten alkali metals, such as sodium. Physical protection is provided by a continuous layer of nickel foil. Heat resistance is provided by an underlying backing layer of thermal insulation. Overlying outer layers of fireproof woven ceramic fibers are used to protect the foil during storage and handling.

Ballif, III, John L. (Salt Lake City, UT); Yuan, Wei W. (Seattle, WA)

1980-01-01

366

Tocopherol content and isomers' composition in selected plant species.  

PubMed

We have analyzed leaves of several plant species for the content and isomers' composition of tocopherols and it was found that their content was considerably higher in some cases than previously reported, especially in autumn tree leaves where the average tocopherols' level was in the range of 300-640 microg/g fresh weight and accounted for 40-140% of the chlorophyll amount. The isomers' composition, usually dominated by alpha-tocopherol in leaves, was different in some plant species with a high percentage of gamma-tocopherol (Kalanchoe, lettuce, dodder species, and young maple leaves) or delta-tocopherol (Cuscuta epithymum and Cuscuta japonica). C. japonica was exceptional by the complete absence of alpha-tocopherol. The possible reasons and physiological significance of these observations have been discussed. PMID:18023194

Szyma?ska, Renata; Kruk, Jerzy

2008-01-01

367

Chemical Composition of Soils of Texas.  

E-print Network

and semi-marshy soils, and (4) flat stream bottom soils. CHEMICAL COMPOSITION OF SOILS OF TEXAS 15 Outline description of series L-colored prairie soils: ke Charles soils: Black, dark-gray or brown, noncalcareous surface soils ? tight on drying... and semi-marshy soils, and (4) flat stream bottom soils. CHEMICAL COMPOSITION OF SOILS OF TEXAS 15 Outline description of series L-colored prairie soils: ke Charles soils: Black, dark-gray or brown, noncalcareous surface soils ? tight on drying...

Fraps, G. S. (George Stronach); Fudge, J. F. (Joseph Franklin)

1937-01-01

368

Composite material including nanocrystals and methods of making  

DOEpatents

Temperature-sensing compositions can include an inorganic material, such as a semiconductor nanocrystal. The nanocrystal can be a dependable and accurate indicator of temperature. The intensity of emission of the nanocrystal varies with temperature and can be highly sensitive to surface temperature. The nanocrystals can be processed with a binder to form a matrix, which can be varied by altering the chemical nature of the surface of the nanocrystal. A nanocrystal with a compatibilizing outer layer can be incorporated into a coating formulation and retain its temperature sensitive emissive properties

Bawendi, Moungi G. (Boston, MA); Sundar, Vikram C. (New York, NY)

2008-02-05

369

Multi-scale Modeling for Piezoelectric Composite Materials  

E-print Network

In this paper, we focus on multi-scale modeling and simulation of piezoelectric composite materials. A multi-scale model for piezoelectric composite materials under the framework of Heterogeneous Multi-scale Method(HMM) is proposed. For materials with periodic microstructure, macroscopic model is derived from microscopic model of piezoelectric composite material by asymptotic expansion. Convergence analysis under the framework of homogenization theory is carried out. Moreover, error estimate between HMM solutions and homogenization solutions is derived. A 3-D numerical example of 1-3 type piezoelectric composite materials is employed to verify the error estimate.

Qian Zhang; Xingye Yue

2014-02-02

370

Synthesis and physico-chemical characterization of a polysialate-hydroxyapatite composite for potential biomedical application  

NASA Astrophysics Data System (ADS)

New composite materials based on aluminosilicate materials were developed to be used in orthopaedic or maxillo-facial surgery. They are called geopolymers or polysialate-siloxo (PSS) and were studied alone or mixed with hydroxyapatite (HAP). The properties of these materials were investigated for potential use in biological or surgery applications. In this work, the chemistry involved in materials preparation was described. Samples were characterized by some physico-chemical methods like X-ray diffraction (XRD), infrared spectrometry (IR) and electron dispersion X-ray spectrometry (EDX). Results indicate that the mixing hydroxyapatite-geopolymer (PSS) leads to a neutral porous composite material with interesting physico-chemical properties. A preliminary evaluation of its cytotoxicity reveals an harmlessness towards fibroblasts. These properties allow to envisage this association as a potential biomaterial.

Zoulgami, M.; Lucas-Girot, A.; Michaud, V.; Briard, P.; Gaudé, J.; Oudadesse, H.

2002-09-01

371

Chemical composition of the SiO2/InSb interface as determined by X-ray photoelectron spectroscopy  

NASA Technical Reports Server (NTRS)

In connection with the relatively poor insulating characteristics of the native oxides of most III-V compound semiconductors, there has been interest in the development of deposited dielectric layers for surface passivation and MOS device fabrication on III-V compound semiconductor substrates. The chemical system of SiO2 deposited on single-crystal InSb substrates has been proposed for the fabrication of IR CCD. The considered investigation is concerned with a detailed examination of the chemical nature of the interactions between deposited and native oxides using X-ray photoelectron spectroscopy (XPS) in conjunction with a chemical-etching technique for depth profiling. The compositional structure of the interfaces obtained in the SiO2/native oxide/InSb system is derived on the basis of an intensity analysis of XPS spectra. Thermal oxidation of the InSb substrate is found to result in an In-rich native oxide and excess elemental Sb at the native oxide/substrate interface.

Vasquez, R. P.; Grunthaner, F. J.

1981-01-01

372

Compression Testing of Textile Composite Materials  

NASA Technical Reports Server (NTRS)

The applicability of existing test methods, which were developed primarily for laminates made of unidirectional prepreg tape, to textile composites is an area of concern. The issue is whether the values measured for the 2-D and 3-D braided, woven, stitched, and knit materials are accurate representations of the true material response. This report provides a review of efforts to establish a compression test method for textile reinforced composite materials. Experimental data have been gathered from several sources and evaluated to assess the effectiveness of a variety of test methods. The effectiveness of the individual test methods to measure the material's modulus and strength is determined. Data are presented for 2-D triaxial braided, 3-D woven, and stitched graphite/epoxy material. However, the determination of a recommended test method and specimen dimensions is based, primarily, on experimental results obtained by the Boeing Defense and Space Group for 2-D triaxially braided materials. They evaluated seven test methods: NASA Short Block, Modified IITRI, Boeing Open Hole Compression, Zabora Compression, Boeing Compression after Impact, NASA ST-4, and a Sandwich Column Test.

Masters, John E.

1996-01-01

373

Carbon Materials Metal/Metal Oxide Nanoparticle Composite and Battery Anode Composed of the Same  

NASA Technical Reports Server (NTRS)

A method of forming a composite material for use as an anode for a lithium-ion battery is disclosed. The steps include selecting a carbon material as a constituent part of the composite, chemically treating the selected carbon material to receive nanoparticles, incorporating nanoparticles into the chemically treated carbon material and removing surface nanoparticles from an outside surface of the carbon material with incorporated nanoparticles. A material making up the nanoparticles alloys with lithium.

Hung, Ching-Cheh (Inventor)

2006-01-01

374

Chemical composition and antimicrobial activities of essential oil and its components from Lebanese Origanum syriacum L  

Microsoft Academic Search

The chemical composition of essential oils isolated by hydrodistillation from the aerial parts of cultivated and wild Origanum syriacum were analyzed by gas chromatograph (GC) and GC\\/mass spectrometry (GC\\/MS). Regardless of growing habitat, both oils were characterized as carvacrol\\/?-terpinene chemotypes. High in vitro antimicrobial activities of essential oil were attributed to the high content of phenolic derivative such as carvacrol.

Ludmilla Ibrahim; Mohamad Karaky; Pascale Ayoub; Nawal El Ajouz; Said Ibrahim

2012-01-01

375

Determining the chemical composition of cloud condensation nuclei  

SciTech Connect

This second progress report describes the status of the project one and one-half years after the start. The goal of the project is to develop the instrumentation to collect cloud condensation nuclei (CCN) in sufficient amounts to determine their chemical composition, and to survey the CCN composition in different climates through a series of field measurements. Our approach to CCN collection is to first form droplets on the nuclei under simulated cloud humidity conditions, which is the only known method of identifying CCN from the background aerosol. Under cloud chamber conditions, the droplets formed become larger than the surrounding aerosol, and can then be removed by inertial impaction. The residue of the evaporated droplets represents the sample to be chemically analyzed. Two size functions of CCN particles are collected by first forming droplets on the large particles are collected by first forming droplets on the large CCN in a haze chamber at 100% relative humidity, and then activating the remaining CCN at 1% supersaturation in a cloud chamber. The experimental apparatus is a serious flow arrangement consisting of an impactor to remove the large aerosol particles, a haze chamber to form droplets on the remaining larger CCN, another impactor to remove the haze droplets containing the larger CCN particles for chemical analysis, a continuous flow diffusion (CFD) cloud chamber to form droplets on the remaining smaller CCN, and a third impactor to remove the droplets for the small CCN sample. Progress is documented here on the development of each of the major components of the flow system. Chemical results are reported on tests to determine suitable wicking material for the different plates. Results of computer modeling of various impactor flows are discussed.

Williams, A.L.; Rothert, J.E.; McClure, K.E. (Illinois State Water Survey, Champaign, IL (United States)); Alofs, D.J.; Hagen, D.E.; White, D.R.; Hopkins, A.R.; Trueblood, M.B. (Missouri Univ., Rolla, MO (USA). Cloud and Aerosol Science Lab.)

1992-02-01

376

Degradation of experimental composite materials and in vitro wear simulation  

NASA Astrophysics Data System (ADS)

The material, mechanical, and clinical aspects of surface degradation of resin composite dental restorative materials by in vitro wear simulation continues to be an area of active research. To investigate wear mechanisms, a series of experimental resin composites with variable and controlled filler particle shape and loading were studied by in vitro wear simulation. The current investigation utilized a simulation that isolated the wear environment, entrapped high and low modulus debris, and evaluated the process including machine and fluid flow dynamics. The degradation was significantly affected by filler particle shape and less by particle loading. The spherical particle composites demonstrated wear loss profiles suggesting an optimized filler loading may exist. This was also demonstrated by the trends in the mechanical properties. Very little difference in magnitude was noted for the wear of irregular particle composites as a function of particulate size; and as a group they were more wear resistant than spherical particle composites. This was the result of different mechanisms of wear that were correlated with the three-dimensional particle shape. The abrasive effects of the aggregate particles and the polymeric stabilization of the irregular shape versus the destabilization and "plucking" of the spherical particles resulted in an unprotected matrix that accounted for significantly greater wear of spherical composite. A model and analysis was developed to explain the events associated with the progressive material wear loss. The initial phase was explained by fatigue-assisted microcracking and loss of material segments in a zone of high stress immediately beneath a point of high stress contact. The early phase was characterized by the development of a small facet primarily by fatigue-assisted microcracking. Although the translation effects were minimal, some three-body and initial two-body wear events were also present. In the late phases, the abrasive effects of the debris aggregate predominated the wear process. The non-linear rate of wear loss was accelerated as the facet deepened. Physical effects, such as thermal fatigue, and chemical effects were less important but contributed to the degradation process. This study provides new insight into the role(s) of high modulus third body debris in the wear of dental composites.

Givan, Daniel Allen

2001-12-01

377

Chemical Composition and Antioxidant Activities of Broussonetia papyrifera Fruits  

PubMed Central

Fruits of Broussonetia papyrifera from South China were analyzed for their total chemical composition, and antioxidant activities in ethanol and aqueous extracts. In the fruit of this plant, the crude protein, crude fat and carbohydrates was 7.08%, 3.72% and 64.73% of dry weight, respectively. The crude protein, crude fat and carbohydrates were 15.71%, 20.51% and 36.09% of dry weight, respectively. Fatty acid and amino acid composition of the fruit were analyzed. Unsaturated fatty acid concentration was 70.6% of the total fatty acids. The percentage of the essential amino acids (EAAs) was 40.60% of the total amino acids. Furthermore, B. papyrifera fruit are rich in many mineral elements and vitamins. Total phenolic content was assessed using the Folin-Ciocalteau assay, whereas antioxidant activities were assessed by measuring the ability of the two extracts to scavenge DPPH radicals, inhibit peroxidation, and chelate ferric ions. Their reducing power was also assessed. Results indicated that the aqueous extract of B. papyrifera was a more potent reducing agent and radical-scavenger than the ethanol extract. GC–MS analysis of the ethanol extract showed the presence of some acid-containing compounds. The changes in total phenolic content and antioxidant capacity in B. papyrifera from four different regions grown under normal conditions were assessed. The antioxidant activity of different extracts was positively associated with their total phenolic content. These results suggest that the fruit of B. papyrifera could be used in dietary supplement preparations, or as a food additive, for nutritional gain, or to prevent oxidation in food products. PMID:22389678

Sun, Jie; Liu, Shao-fang; Zhang, Chu-shu; Yu, Li-na; Bi, Jie; Zhu, Feng; Yang, Qing-li

2012-01-01

378

High Temperature Materials for Chemical Propulsion Applications  

NASA Technical Reports Server (NTRS)

Radiation or passively cooled thrust chambers are used for a variety of chemical propulsion functions including apogee insertion, reaction control for launch vehicles, and primary propulsion for planetary spacecraft. The performance of these thrust chambers is limited by the operating temperature of available materials. Improved oxidation resistance and increased operating temperatures can be achieved with the use of thermal barrier coatings such as zirconium oxide (ZrO2) and hafnium oxide (HfO2). However, previous attempts to include these materials showed cracking and spalling of the oxide layer due to poor bonding. Current research at NASA's Marshall Space Flight Center (MSFC) has generated unique, high temperature material options for in-space thruster designs that are capable of up to 2500 C operating temperatures. The research is focused on fabrication technologies to form low cost Iridium,qF_.henium (Ir/Re) components with a ceramic hot wall created as an integral, functionally graded material (FGM). The goal of this effort is to further de?celop proven technologies for embedding a protective ceramic coating within the Ir/Re liner to form a robust functional gradient material. Current work includes the fabrication and testing of subscale samples to evaluate tensile, creep, thermal cyclic/oxidation, and thermophysical material properties. Larger test articles have also being fabricated and hot-fire tested to demonstrate the materials in prototype thrusters at 1O0 lbf thrust levels.

Elam, Sandra; Hickman, Robert; O'Dell, Scott

2007-01-01

379

Flame-retardant composite materials  

NASA Technical Reports Server (NTRS)

The properties of eight different graphite composite panels fabricated using four different resin matrices and two types of graphite reinforcement are described. The resin matrices included: VPSP/BMI, a blend of vinylpolystyryl pyridine and bismaleimide; BMI, a bismaleimide; and phenolic and PSP, a polystyryl pyridine. The graphite fiber used was AS-4 in the form of either tape or fabric. The properties of these composites were compared with epoxy composites. It was determined that VPSP/BMI with the graphite tape was the optimum design giving the lowest heat release rate.

Kourtides, Demetrius A.

1991-01-01

380

A computational study into the (tetrahedral) distortion of TX {sub 2} {alpha}-quartz materials: The effect of changing the chemical composition away from SiO{sub 2}  

SciTech Connect

We report a periodic density functional study into the tetrahedral distortion of a range of quartz-like TX {sub 2} materials. The total tetrahedral distortion and its most sizable contribution, the angular part (angular tetrahedral distortion), are found to be strongly dependent on the chemical composition and to increase in the order of BeF{sub 2}chemical composition. The sulphide materials in the study were found to have tetrahedral distortion values commonly associated in silica with experimentally unrealizable hypothetical frameworks, suggesting that such frameworks might become realizable when stepping away from silica. None of the tetrahedra were found to be strictly regular, in line with the analysis of Smith [Acta. Cryst. 16 (1963) 542-545], demonstrating that regular tetrahedra are in principle possible in quartz but that distortions from ideality are energetically advantageous. The energetic reason for this distortion is still an open question; we propose a simple electrostatic model that explains the ease with which tetrahedra can be distorted in terms of charge transfer and the relative charge on the X (O,S,F) atom. - Graphical Abstract: View on a quartz unit-cell with TX {sub 4} tetrahedra. Display Omitted.

Zwijnenburg, Martijn A. [Davy Faraday Research Laboratory, The Royal Institution of Great Britain, 21 Albemarle Street, London W1S 4BS (United Kingdom)]. E-mail: martijn@ri.ac.uk; Huenerbein, Robert [Davy Faraday Research Laboratory, The Royal Institution of Great Britain, 21 Albemarle Street, London W1S 4BS (United Kingdom); Bell, Robert G. [University College London, Department of Chemistry, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Davy Faraday Research Laboratory, The Royal Institution of Great Britain, 21 Albemarle Street, London W1S 4BS (United Kingdom); Cora, Furio [University College London, Department of Chemistry, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Davy Faraday Research Laboratory, The Royal Institution of Great Britain, 21 Albemarle Street, London W1S 4BS (United Kingdom)

2006-11-15

381

Ethylene vinylacetate copolymer and nanographite composite as chemical vapour sensor  

NASA Astrophysics Data System (ADS)

Polymer-nanostructured carbon composite as chemical vapour sensor is described, made by the dissolution method of a non-conductive polymer, ethylene vinylacetate copolymer, mixed with conductive nanographite particles (carbon black). Sensor exhibits relative electrical resistance change in chemical vapours, like ethanol and toluene. Since the sensor is relatively cheap, easy to fabricate, it can be used in air quality monitoring and at industries to control hazardous substance concentration in the air, for example, to protect workers from exposure to chemical spills.

Stepina, Santa; Sakale, Gita; Knite, Maris

2013-12-01

382

Impact of solids on composite materials  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

383

Flexible Composite-Material Pressure Vessel  

NASA Technical Reports Server (NTRS)

A proposed lightweight pressure vessel would be made of a composite of high-tenacity continuous fibers and a flexible matrix material. The flexibility of this pressure vessel would render it (1) compactly stowable for transport and (2) more able to withstand impacts, relative to lightweight pressure vessels made of rigid composite materials. The vessel would be designed as a structural shell wherein the fibers would be predominantly bias-oriented, the orientations being optimized to make the fibers bear the tensile loads in the structure. Such efficient use of tension-bearing fibers would minimize or eliminate the need for stitching and fill (weft) fibers for strength. The vessel could be fabricated by techniques adapted from filament winding of prior composite-material vessels, perhaps in conjunction with the use of dry film adhesives. In addition to the high-bias main-body substructure described above, the vessel would include a low-bias end substructure to complete coverage and react peak loads. Axial elements would be overlaid to contain damage and to control fiber orientation around side openings. Fiber ring structures would be used as interfaces for connection to ancillary hardware.

Brown, Glen; Haggard, Roy; Harris, Paul A.

2003-01-01

384

Fourth Symposium on Composite Materials  

Microsoft Academic Search

The high temperature fatigue of a (O)12 tungsten fiber reinforced copper matrix composite was investigated. Specimens having fiber volume percentages of 10 and 36 were fatigued under fully-reversed, strain-controlled conditions at both 260 and 560 C. The fatigue life was found to be independent of fiber volume fraction because fatigue damage preferentially occurred in the matrix. Also, the composite fatigue

M. J. Verrilli; T. P. Gabb

1990-01-01

385

The study of chemical composition and elemental mappings of colored over-glaze porcelain fired in Qing Dynasty by micro-X-ray fluorescence  

NASA Astrophysics Data System (ADS)

It is very difficult to measure the chemical composition of colored pigments of over-glaze porcelain by X-ray fluorescence because it contains high concentration of Pb. One of the disadvantages of our polycapillary optics is that it has low transmission efficiency to the high energy X-ray. However, it is beneficial to measure the chemical compositions of rich Pb sample. In this paper, we reported the performances of a tabletop setup of micro-X-ray fluorescence system base on slightly focusing polycapillary and its applications for analysis of rich Pb sample. A piece of Chinese ancient over-glaze porcelain was analyzed by micro-X-ray fluorescence. The experimental results showed that the Cu, Fe and Mn are the major color elements. The possibilities of the process of decorative technology were discussed in this paper, also.

Lin, Cheng; Meitian, Li; Youshi, Kim; Changsheng, Fan; Shanghai, Wang; Qiuli, Pan; Zhiguo, Liu; Rongwu, Li

2011-02-01

386

Chemical synthesis of poly(aniline-co-o\\/m-toluidine)\\/V 2O 5 nano composites and their characterizations  

Microsoft Academic Search

Chemical oxidative polymerization of aniline (ANI) and o\\/m-toluidine (OT or MT) and their nano composites at different experimental conditions were performed using peroxydisulfate (PDS) as a lone chemical initiator and V2O5 as a host material in an aqueous HCl medium at 45°C under nitrogen atmosphere. The nano composites were synthesized under different experimental conditions and were characterized by Fourier transform

J. Juliet Latha Jeyakumari; A. Yelilarasi; B. Sundaresan; V. Dhanalakshmi; R. Anbarasan

2010-01-01

387

Material Handling and Storage Table Of Contents  

E-print Network

handling needs by engineering; b. Movement by mechanical device (e.g., lift truck, overhead crane.02 Material hoist towers, masts, guy or braces, counterweights, drive machinery supports, sheave.03 Hoist towers shall be erected and dismantled only under the direct supervision of a qualified

US Army Corps of Engineers

388

Amino acid composition of processed fish silage using different raw materials  

Microsoft Academic Search

The objective was to evaluate amino acid composition of silages produced from three raw materials. Commercial marine fish waste, commercial freshwater fish waste, and tilapia filleting residue were used to produce fish silage by acid digestion (20ml\\/kg formic acid and 20ml\\/kg sulfuric acid) and anaerobic fermentation (50g\\/kg Lactobacillus plantarum, 150g\\/kg sugar cane molasses). Protein content and amino acid composition were

Rose Meire Vidotti; Elisabete Maria Macedo Viegas; Dalton José Carneiro

2003-01-01

389

Improve the physical and chemical properties of biocompatible polymer material by MeV He ion beam  

NASA Astrophysics Data System (ADS)

There is a high interest in improving the hydrophilicity of polymer surfaces due to their wide use for technological purposes. In this study Ultra High Molecular Weight Polyethylene (UHMWPE) as a biocompatible material was bombarded with 1 MeV He ions to the fluences ranging from 1×1013 to 5×1014 cm-2. The pristine and ion beam modified samples were investigated by photoluminescence (PL), ultraviolet-visible (UV-vis) spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The changes of wettability and surface free energy were determined by the contact angle measurements. The obtained results showed that the ion bombardment induced decrease in integrated luminescence intensity and decrease in the transmittance with increase of ion fluence as well. This is might be attributed to degradation of polymer surface and/or creation of new electronic levels in the forbidden gap. The FTIR spectral studies indicate that the ion beam induces chemical modifications within the bombarded UHMWPE. Formation of carbonyl groups (C=O) on the polymer surface was studied. Direct relationship of the wettability and surface free energy of the bombarded polymer with the ion fluences was observed.

Abdul-Kader, A. M.; El-Gendy, Y. A.; Al-Rashdy, Awad A.

2012-07-01

390

New textile composite materials development, production, application  

NASA Technical Reports Server (NTRS)

New textile composite materials development, production, and application are discussed. Topics covered include: super-high-strength, super-high-modulus fibers, filaments, and materials manufactured on their basis; heat-resistant and nonflammable fibers, filaments, and textile fabrics; fibers and textile fabrics based on fluorocarbon poylmers; antifriction textile fabrics based on polyfen filaments; development of new types of textile combines and composite materials; and carbon filament-based fabrics.

Mikhailov, Petr Y.

1993-01-01

391

EFFECTS OF TOUGHENED MATRIX RESINS ON COMPOSITE MATERIALS FOR WIND TURBINE BLADES  

E-print Network

EFFECTS OF TOUGHENED MATRIX RESINS ON COMPOSITE MATERIALS FOR WIND TURBINE BLADES by Ricardo Orozco. Finally, I would like to thank Sandia National Laboratories for supporting this research and the wind turbine energy project. #12;v TABLE OF CONTENTS LIST OF TABLES

392

Materials Science and Engineering A 528 (2011) 81878197 Contents lists available at ScienceDirect  

E-print Network

Materials Science and Engineering A 528 (2011) 8187­8197 Contents lists available at ScienceDirect Materials Science and Engineering A journal homepage: www.elsevier.com/locate/msea Application of a dynamic-mixture shock-wave model to the metal­matrix composite materials M. Grujicica, , B. Pandurangana , W.C. Bella

Grujicic, Mica

393

Modeling of resonant magneto-electric effect in a magnetostrictive and piezoelectric laminate composite structure coupled by a bonding material  

NASA Astrophysics Data System (ADS)

The harmonic magneto-electro-elastic vibration of a thin laminated composite was considered. A theoretical model, including shear lag and vibration effects was developed for predicting the magneto-electric (ME) effect in a laminate composite consisting of magnetostrictive and piezoelectric layers. To avoid bending, we assumed that the composite was geometrically symmetric. For finite length symmetrically fabricated laminates, we derived the dynamic strain-stress field and ME coefficients, including shear lag and vibration effects for several boundary conditions. Parametric studies are presented to evaluate the influences of material properties and geometries on the strain distribution and the ME coefficient. Analytical expressions indicate that the shear lag and the vibration frequency strongly influence the strain distribution in the laminates and these effects strongly influence the ME coefficients.

Hasanyan, D.; Wang, Y.; Gao, J.; Li, M.; Shen, Y.; Li, J.; Viehland, D.

2012-09-01

394

[Determination of the content of sulfur of coal by the infrared absorption method with high acccuracy].  

PubMed

The present paper reported the differential scanning calorimetry-thermogravimetry curves and the infrared (IR) absorption spectrometry under the temperature program analyzed by the combined simultaneous thermal analysis-IR spectrometer. The gas products of coal were identified by the IR spectrometry. This paper emphasized on the combustion at high temperature-IR absorption method, a convenient and accurate method, which measures the content of sulfur in coal indirectly through the determination of the content of sulfur dioxide in the mixed gas products by IR absorption. It was demonstrated, when the instrument was calibrated by varied pure compounds containing sulfur and certified reference materials (CRMs) for coal, that there was a large deviation in the measured sulfur contents. It indicates that the difference in chemical speciations of sulfur between CRMs and the analyte results in a systematic error. The time-IR absorption curve was utilized to analyze the composition of sulfur at low temperatures and high temperatures and then the sulfur content of coal sample was determined by using a CRM for coal with a close composition of sulfur. Therefore, the systematic error due to the difference in chemical speciations of sulfur between the CRM and analyte was eliminated. On the other hand, in this combustion at high temperature-IR absorption method, the mass of CRM and analyte were adjusted to assure the sulfur mass equal and then the CRM and the analyte were measured alternately. This single-point calibration method reduced the effect of the drift of the IR detector and improved the repeatability of results, compared with the conventional multi-point calibration method using the calibration curves of signal intensity vs sulfur mass. The sulfur content results and their standard deviations of an anthracite coal and a bituminous coal with a low sulfur content determined by this modified method were 0.345% (0.004%) and 0.372% (0.008%), respectively. The uncertainty (U, k =2) of sulfur contents of two coal samples was evaluated to be 0.019% and 0.021%, respectively. Two main modifications, namely the calibration using the coal CRM with a similar composition of low-temperature sulfur and high temperature sulfur, and the single-point calibration alternating CRM and analyte, endow the combustion at high temperature-IR absorption method with an accuracy obviously better than that of the ASTM method. Therefore, this modified method has a well potential in the analysis of sulfur content. PMID:24822403

Wang, Hai-Feng; Lu, Hai; Li, Jia; Sun, Guo-Hua; Wang, Jun; Dai, Xin-Hua

2014-02-01

395

Chemical composition and antibacterial activity of propolis collected by three different races of honeybees in the same region  

Microsoft Academic Search

The chemical analysis and antibacterial activity of three types of propolis collected three different races of Apis mellifera bee in the same apiary were investigated. Propolis samples were investigated by GC\\/MS, 48 compounds were identified 32 being new for propolis. The compounds identified indicated that the main plant sources of propolis were Populus alba, Populus tremuloides and Salix alba. The

Sibel Silici; Semiramis Kutluca

2005-01-01

396

Brazilian kefir: structure, microbial communities and chemical composition  

PubMed Central

Microbial ecology and chemical composition of Brazilian kefir beverage was performed. The microorganisms associated with Brazilian kefir were investigated using a combination of phenotypic and genotypic methods. A total of 359 microbial isolates were identified. Lactic acid bacteria (60.5%) were the major isolated group identified, followed by yeasts (30.6%) and acetic acid bacteria (8.9%). Lactobacillus paracasei (89 isolates), Lactobacillus parabuchneri (41 isolates), Lactobacillus casei (32 isolates), Lactobacillus kefiri (31 isolates), Lactococcus lactis (24 isolates), Acetobacter lovaniensis (32 isolates), Kluyveromyces lactis (31 isolates), Kazachstania aerobia (23 isolates), Saccharomyces cerevisiae (41 isolates) and Lachancea meyersii (15 isolates) were the microbial species isolated. Scanning electron microscopy showed that the microbiota was dominated by bacilli (short and curved long) cells growing in close association with lemon-shaped yeasts cells. During the 24 h of fermentation, the protein content increased, while lactose and fat content decreased. The concentration of lactic acid ranged from 1.4 to 17.4 mg/ml, and that of acetic acid increased from 2.1 to 2.73 mg/ml. The production of ethanol was limited, reaching a final mean value of 0.5 mg/ml. PMID:24031681

Magalhães, Karina Teixeira; de Melo Pereira, Gilberto Vinícius; Campos, Cássia Roberta; Dragone, Giuliano; Schwan, Rosane Freitas

2011-01-01

397

Chemical composition of Schiff's reagent crystals.  

PubMed

Crystals were prepared by adding 0.04 M sulfuric acid to a Schiff's reagent made with 2.5 g pararosaniline (PR) chloride dissolved in a saturated SO2 solution. Elemental analysis of the crystals gave the composition C19H21N3S2O7.4H2O which corresponds to the sulfate of pararosanilinesulfonic acid (PRSA) tetrahydrate. The moisture content was ca. 5%. A reagent reconstituted by dissolving 0.2 grams of crystals in HCl 0.1 N contains ca. 3.5 x 10(-3) M or 0.11% PR. A solution prepared with 2.5 g PR in 100 ml O.1 N HCl plus 0.04 M M K2S2O5 gave only a few crystals after 0.04 M sulfuric acid was added. The PR content, determined colorimetrically, was 0.25% compared with 1.35% in saturated SO2. The per cent dye loss during charcoal purification was also higher. The low concentration of PR, caused both by the lower solubility and by the larger loss during charcoal purification explains the poor yield of crystals of a reagent prepared in HCl/K2S2O5, compared to a reagent prepared in saturated SO2. After crystallization is complete, the crystals are in equilibrium with a concentration of 0.2% of PR in the supernatant: when the initial concentration is close to this value crystallization is negligible or completely fails. PMID:8835187

Galassi, L; De Napoli, F

1995-01-01

398

Composition/bandgap selective dry photochemical etching of semiconductor materials  

DOEpatents

Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg/sub 1/ in the presence of a second semiconductor material of a different composition and direct bandgap Eg/sub 2/, wherein Eg/sub 2/ > Eg/sub 1/, said second semiconductor material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg/sub 1/ but less than Eg/sub 2/, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

Ashby, C.I.H.; Dishman, J.L.

1985-10-11

399

Composition/bandgap selective dry photochemical etching of semiconductor materials  

DOEpatents

A method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg.sub.1 in the presence of a second semiconductor material of a different composition and direct bandgap Eg.sub.2, wherein Eg.sub.2 >Eg.sub.1, said second semiconductor material substantially not being etched during said method, comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg.sub.1 but less than Eg.sub.2, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

Ashby, Carol I. H. (Edgewood, NM); Dishman, James L. (Albuquerque, NM)

1987-01-01

400

Understanding and tuning nanostructured materials for chemical energy conversion  

NASA Astrophysics Data System (ADS)

The conversion of energy that employs chemical reaction is termed chemical energy conversion. In my dissertation, I have focused on chemical energy conversion systems involving energetic materials and lithium ion batteries, where performance is strongly dependent on the properties of materials and their architecture. The objective of this study is to enhance our understanding and tuning of nanostructured materials that might find application toward energetic materials and electrode materials in lithium ion batteries. Rapid heating diagnostics tools, i.e. temperature-jump techniques, have been used to study the ignition of aluminum nanoparticles, nanothermite reaction mechanism and metal oxides nanoparticles decomposition under rapid heating conditions (˜105-106 K/s). Time-resolved mass spectra results support the hypothesis that Al containing species diffuse outwards through the oxide shell. Low effective activation energies were found for metal oxides nanoparticles decomposition at high heating rates, implying the mass transfer control at high heating rates. The role of oxygen release from oxidizer in nanothermite reactions have been examined for several different systems, including some using microsized oxidizer (i.e., nano-Al/micro-I 2O5). In particular, for periodate based nanothermites, direct evidence from high heating rate SEM and mass spectrometry results support that direct gas phase oxygen release from oxidizer decomposition is critical in its ignition and combustion. Efforts have also been made to synthesize nanostructured materials for nanoenergetic materials and lithium ion batteries applications. Hollow CuO spheres were synthesized by aerosol spray pyrolysis, employing a gas blowing mechanism for the formation of hollow structure during aerosol synthesis. The materials synthesized as oxidizers in nanothermite demonstrated superior performance, and of particular note, periodate salts based nanothermite demonstrated the best gas generating performance for nanothermite materials. Energetic composite nanofibrous mats (NC/Al-CuO, NC/Al-Fe2O3, and NC/Al-Bi2O3) were also prepared by an electrospinning method and evaluated for their combustion performance. Aerosol spray pyrolysis was employed to produce carbon coated CuO hollow spheres, Mn3O4 hollow spheres, and Fe2O 3 mesoporous spheres. These hollow/mesoporous spheres demonstrated superior electrochemical performance when used as anode materials in lithium ion batteries. The effects of the amorphous and crystal structures on the electrochemical performance and the structure evolution during electrochemical tests were also investigated.

Jian, Guoqiang