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Sample records for carbide composite bodies

  1. Composite materials and bodies including silicon carbide and titanium diboride and methods of forming same

    DOEpatents

    Lillo, Thomas M.; Chu, Henry S.; Harrison, William M.; Bailey, Derek

    2013-01-22

    Methods of forming composite materials include coating particles of titanium dioxide with a substance including boron (e.g., boron carbide) and a substance including carbon, and reacting the titanium dioxide with the substance including boron and the substance including carbon to form titanium diboride. The methods may be used to form ceramic composite bodies and materials, such as, for example, a ceramic composite body or material including silicon carbide and titanium diboride. Such bodies and materials may be used as armor bodies and armor materials. Such methods may include forming a green body and sintering the green body to a desirable final density. Green bodies formed in accordance with such methods may include particles comprising titanium dioxide and a coating at least partially covering exterior surfaces thereof, the coating comprising a substance including boron (e.g., boron carbide) and a substance including carbon.

  2. Silicon nitride/silicon carbide composite powders

    DOEpatents

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1996-06-11

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  3. Silicon carbide reinforced silicon carbide composite

    NASA Technical Reports Server (NTRS)

    Lau, Sai-Kwing (Inventor); Calandra, Salvatore J. (Inventor); Ohnsorg, Roger W. (Inventor)

    2001-01-01

    This invention relates to a process comprising the steps of: a) providing a fiber preform comprising a non-oxide ceramic fiber with at least one coating, the coating comprising a coating element selected from the group consisting of carbon, nitrogen, aluminum and titanium, and the fiber having a degradation temperature of between 1400.degree. C. and 1450.degree. C., b) impregnating the preform with a slurry comprising silicon carbide particles and between 0.1 wt % and 3 wt % added carbon c) providing a cover mix comprising: i) an alloy comprising a metallic infiltrant and the coating element, and ii) a resin, d) placing the cover mix on at least a portion of the surface of the porous silicon carbide body, e) heating the cover mix to a temperature between 1410.degree. C. and 1450.degree. C. to melt the alloy, and f) infiltrating the fiber preform with the melted alloy for a time period of between 15 minutes and 240 minutes, to produce a ceramic fiber reinforced ceramic composite.

  4. Joining of porous silicon carbide bodies

    DOEpatents

    Bates, Carl H.; Couhig, John T.; Pelletier, Paul J.

    1990-05-01

    A method of joining two porous bodies of silicon carbide is disclosed. It entails utilizing an aqueous slip of a similar silicon carbide as was used to form the porous bodies, including the sintering aids, and a binder to initially join the porous bodies together. Then the composite structure is subjected to cold isostatic pressing to form a joint having good handling strength. Then the composite structure is subjected to pressureless sintering to form the final strong bond. Optionally, after the sintering the structure is subjected to hot isostatic pressing to further improve the joint and densify the structure. The result is a composite structure in which the joint is almost indistinguishable from the silicon carbide pieces which it joins.

  5. Composition Comprising Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Mehregany, Mehran (Inventor); Zorman, Christian A. (Inventor); Fu, Xiao-An (Inventor); Dunning, Jeremy L. (Inventor)

    2012-01-01

    A method of depositing a ceramic film, particularly a silicon carbide film, on a substrate is disclosed in which the residual stress, residual stress gradient, and resistivity are controlled. Also disclosed are substrates having a deposited film with these controlled properties and devices, particularly MEMS and NEMS devices, having substrates with films having these properties.

  6. Silicon nitride/silicon carbide composite densified materials prepared using composite powders

    DOEpatents

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1997-07-01

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  7. Diamond-silicon carbide composite

    DOEpatents

    Qian, Jiang; Zhao, Yusheng

    2006-06-13

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5–8 GPa, T=1400K–2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.dot.m1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  8. Process for making silicon carbide reinforced silicon carbide composite

    NASA Technical Reports Server (NTRS)

    Lau, Sai-Kwing (Inventor); Calandra, Salavatore J. (Inventor); Ohnsorg, Roger W. (Inventor)

    1998-01-01

    A process comprising the steps of: a) providing a fiber preform comprising a non-oxide ceramic fiber with at least one coating, the coating comprising a coating element selected from the group consisting of carbon, nitrogen, aluminum and titanium, and the fiber having a degradation temperature of between 1400.degree. C. and 1450.degree. C., b) impregnating the preform with a slurry comprising silicon carbide particles and between 0.1 wt % and 3 wt % added carbon c) providing a cover mix comprising: i) an alloy comprising a metallic infiltrant and the coating element, and ii) a resin, d) placing the cover mix on at least a portion of the surface of the porous silicon carbide body, e) heating the cover mix to a temperature between 1410.degree. C. and 1450.degree. C. to melt the alloy, and f) infiltrating the fiber preform with the melted alloy for a time period of between 15 minutes and 240 minutes, to produce a ceramic fiber reinforced ceramic composite.

  9. Body Composition.

    ERIC Educational Resources Information Center

    Mayhew, Jerry L.

    1981-01-01

    Body composition refers to the types and amounts of tissues which make up the body. The most acceptable method for assessing body composition is underwater weighing. A subcutaneous skinfold provides a quantitative measurement of fat below the skin. The skinfold technique permits a valid estimate of the body's total fat content. (JN)

  10. Diamond-silicon carbide composite and method

    DOEpatents

    Zhao, Yusheng

    2011-06-14

    Uniformly dense, diamond-silicon carbide composites having high hardness, high fracture toughness, and high thermal stability are prepared by consolidating a powder mixture of diamond and amorphous silicon. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPam.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness.

  11. Carbides composite surface layers produced by (PTA)

    NASA Astrophysics Data System (ADS)

    Tajoure, Meloud; Tajouri, Ali; Abuzriba, Mokhtar; Akreem, Mosbah

    2013-12-01

    The plasma transferred arc technique was applied to deposit a composite layer of nickel base with tungsten carbide in powder form on to surface of low alloy steel 18G2A type according to polish standard. Results showed that, plasma transferred arc hard facing process was successfully conducted by using Deloro alloy 22 plus tungsten carbide powders. Maximum hardness of 1489 HV and minimum dilution of 8.4 % were achieved by using an arc current of 60 A. However, when the current was further increased to 120 A & the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base deposit with tungsten carbide features uniform distribution of reinforcement particles with regular grain shape half - dissolved in the matrix.

  12. Carbides composite surface layers produced by (PTA)

    SciTech Connect

    Tajoure, Meloud; Tajouri, Ali E-mail: dr.mokhtarphd@yahoo.com; Abuzriba, Mokhtar E-mail: dr.mokhtarphd@yahoo.com; Akreem, Mosbah

    2013-12-16

    The plasma transferred arc technique was applied to deposit a composite layer of nickel base with tungsten carbide in powder form on to surface of low alloy steel 18G2A type according to polish standard. Results showed that, plasma transferred arc hard facing process was successfully conducted by using Deloro alloy 22 plus tungsten carbide powders. Maximum hardness of 1489 HV and minimum dilution of 8.4 % were achieved by using an arc current of 60 A. However, when the current was further increased to 120 A and the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base deposit with tungsten carbide features uniform distribution of reinforcement particles with regular grain shape half - dissolved in the matrix.

  13. Silicon carbide material sintered bodies manufacturing

    NASA Technical Reports Server (NTRS)

    Suzuki, K.; Shinohara, N.

    1984-01-01

    A method is described for producing a high density silicon carbide sintering substance which contains aluminum oxide. The sintering is done in CO gas atmosphere, which is kept at 2 to 20 atmospheric pressures.

  14. Development of silicon carbide composites for fusion

    SciTech Connect

    Snead, L.L. )

    1993-08-01

    The use of silicon carbide composites for structural materials is of growing interest in the fusion community. However, radiation effects in these materials are virtually unexplored, and the general state of ceramic matrix composites for nonnuclear applications is still in its infancy. Research into the radiation response of the most popular silicon carbide composite, namely, the chemically vapor-deposited (CVD) SiC-carbon-Nicalon fiber system is discussed. Three areas of interest are the stability of the fiber and matrix materials, the stability of the fiber-matrix interface, and the true activation of these [open quotes]reduced activity[close quotes] materials. Two methods are presented that quantitatively measure the effect of radiation on fiber and matrix elastic modulus as well as the fiber-matrix interfacial strength. The results of these studies show that the factor limiting the radiation performance of the CVD SiC-carbon-Nicalon system is degradation of the Nicalon fiber, which leads to a weakened carbon interface. The activity of these composites is significantly higher than expected and is dominated by impurity isotopes. 52 refs., 12 figs., 3 tabs.

  15. Method for producing silicon nitride/silicon carbide composite

    DOEpatents

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1996-07-23

    Silicon carbide/silicon nitride composites are prepared by carbothermal reduction of crystalline silica powder, carbon powder and optionally crsytalline silicon nitride powder. The crystalline silicon carbide portion of the composite has a mean number diameter less than about 700 nanometers and contains nitrogen.

  16. Molybdenum disilicide composites reinforced with zirconia and silicon carbide

    DOEpatents

    Petrovic, J.J.

    1995-01-17

    Compositions are disclosed consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

  17. Molybdenum disilicide composites reinforced with zirconia and silicon carbide

    DOEpatents

    Petrovic, John J.

    1995-01-01

    Compositions consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

  18. Combustion synthesis of oxide-carbide composites

    SciTech Connect

    Wang, L.L.; Munir, Z.A. . Div. of Materials Science and Engineering)

    1990-02-01

    Synthesis of an oxide-carbide composite material through a self- propagating reaction process can be achieved by coupling a highly exothermic thermite reaction and a weakly exothermic carbide reaction. Two systems, one with Al and the other with Mg as the reducing agent in the presence of B{sub 2}O{sub 3} and carbon, are used as the reaction models for this investigation. Based on the experimental results, the formation Al{sub 2}O{sub 3}-B{sub 4}C and MgO-N{sub 4}C composites is proposed to involve a two-step sequential reaction mechanism. The highly exothermic thermite reaction between the reducing agent and B{sub 2}O{sub 3} occurs first, and the heat generated subsequently brings about the formation of B{sub 4}C between the liberated boron and the carbon. The exothermic reaction between Al and B{sub 2}O{sub 3} is initiated at about 850{degrees}C. In the reaction between Mg and B{sub 2}O{sub 3}, however, the interaction between Mg and B{sub 2}O{sub 3} depends on the surrounding inert gas pressure due to the high volatility of Mg. The interaction changes from one involving gaseous Mg and liquid B{sub 2}O{sub 3} to one involving liquid Mg and liquid B{sub 2}O{sub 3} as the pressure increases. In both systems, reactions between the metallic oxides (i.e. Al{sub 2}O{sub 3} or MgO) and B{sub 2}O{sub 3} compete with the thermite reaction. Although it is possible to synthesize B{sub 4}C from carbon fibers in the 6Mg+B{sub 2+}O{sub 3}+C system, the carbon fiber is only partially converted, and the carbide formed is loosely attached to the unreacted carbon core. 17 refs., 23 figs., 3 tabs.

  19. Carbide coated fibers in graphite-aluminum composites

    NASA Technical Reports Server (NTRS)

    Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

    1975-01-01

    The study of protective-coupling layers of refractory metal carbides on the graphite fibers prior to their incorporation into composites is presented. Such layers should be directly wettable by liquid aluminum and should act as diffusion barriers to prevent the formation of aluminum carbide. Chemical vapor deposition was used to uniformly deposit thin, smooth, continuous coats of ZrC on the carbon fibers of tows derived from both rayon and polyacrylonitrile. A wet chemical coating of the fibers, followed by high-temperature treatment, was used, and showed promise as an alternative coating method. Experiments were performed to demonstrate the ability of aluminum alloys to wet carbide surfaces. Titanium carbide, zirconium carbide and carbide-coated graphite surfaces were successfully wetted. Results indicate that initial attempts to wet surfaces of ZrC-coated carbon fibers appear successful.

  20. Silicon carbide sintered body manufactured from silicon carbide powder containing boron, silicon and carbonaceous additive

    NASA Technical Reports Server (NTRS)

    Tanaka, Hidehiko

    1987-01-01

    A silicon carbide powder of a 5-micron grain size is mixed with 0.15 to 0.60 wt% mixture of a boron compound, i.e., boric acid, boron carbide (B4C), silicon boride (SiB4 or SiB6), aluminum boride, etc., and an aluminum compound, i.e., aluminum, aluminum oxide, aluminum hydroxide, aluminum carbide, etc., or aluminum boride (AlB2) alone, in such a proportion that the boron/aluminum atomic ratio in the sintered body becomes 0.05 to 0.25 wt% and 0.05 to 0.40 wt%, respectively, together with a carbonaceous additive to supply enough carbon to convert oxygen accompanying raw materials and additives into carbon monoxide.

  1. Abrasive slurry composition for machining boron carbide

    DOEpatents

    Duran, E.L.

    1984-11-29

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  2. Abrasive slurry composition for machining boron carbide

    DOEpatents

    Duran, Edward L.

    1985-01-01

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  3. Ductile intermetallic toughened carbide matrix composites

    SciTech Connect

    Plucknett, K.P.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.; Menchhofer, P.A.

    1996-08-01

    Ductile Ni{sub 3}Al alloys have been used as binder phase for fabrication of TiC and WC matrix composites. Ni{sub 3}Al has good corrosion resistance to aqueous acidic environments, and its yield strength increases with temperature to a max at 700-800 C; this combined with high tensile ductilities (up to 50% strain) make Ni{sub 3}Al attractive for replacing Co in cemented carbides. Materials have been fabricated by both hot pressing and vacuum sintering, with Ni{sub 3}Al contents of 15 to 95 vol%. Vacuum sintering cycles, similar to those used for WC/Co and TiC/Ni (1450-1600 C), resulted in sintered densities >95% theoretical. WC/Ni{sub 3}Al materials showed an order of magnitude improvement in corrosion resistance over WC/Co, in sulfuric/nitric acid. These materials also had improved high temperature strength retention compared to WC/Co cermets, though initial RT strengths were lower. Fracture toughness varied between 8 and 25 MPa.m{sup 1/2} and depended primarily on Ni{sub 3}Al content and composition.

  4. Sintered silicon carbide molded body and method for its production

    NASA Technical Reports Server (NTRS)

    Omori, M.; Sendai, M.; Ohira, K.

    1984-01-01

    Sintered silicon carbide shapes are described. They are produced by using a composition containing an oxide of at least one element chosen from the group: Li, Be, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Nb, Mo, Ba, Tc, Ta, W and Th as a supplement to known sintering aids.

  5. Carbide-reinforced metal matrix composite by direct metal deposition

    NASA Astrophysics Data System (ADS)

    Novichenko, D.; Thivillon, L.; Bertrand, Ph.; Smurov, I.

    Direct metal deposition (DMD) is an automated 3D laser cladding technology with co-axial powder injection for industrial applications. The actual objective is to demonstrate the possibility to produce metal matrix composite objects in a single-step process. Powders of Fe-based alloy (16NCD13) and titanium carbide (TiC) are premixed before cladding. Volume content of the carbide-reinforced phase is varied. Relationships between the main laser cladding parameters and the geometry of the built-up objects (single track, 2D coating) are discussed. On the base of parametric study, a laser cladding process map for the deposition of individual tracks was established. Microstructure and composition of the laser-fabricated metal matrix composite objects are examined. Two different types of structures: (a) with the presence of undissolved and (b) precipitated titanium carbides are observed. Mechanism of formation of diverse precipitated titanium carbides is studied.

  6. Silicon Carbide- Based Materials for Joining Silicon Carbide Composites for Fusion Energy Applications

    SciTech Connect

    Lewinsohn, Charles A. ); Jones, Russell H. ); Colombo, Paolo; Riccardi, B

    2002-12-01

    This paper describes issues related to using silicon carbide derived from inorganic polymer precursors for joining silicon carbide composites for fusion energy applications. Evolution of gases and shrinkage during processing are identified as critical processes that may control the presence of strength limiting flaws and residual stresses. Precursor composition and structure effect the amount of gaseous species evolved during processing, chemical compatibility with substrates, and processing environments. Results from the literature and from the authors' investigations are used to illustrate the use of polymer derived material for joining.

  7. Silicon Carbide and Silicon Carbide Composites for Fusion Reactor Applications

    SciTech Connect

    Hinoki, Tatsuya; Hasegawa, Akira; Katoh, Yutai; Snead, Lance Lewis; Jung, H.C.; Katsui, Hirokazu; Kondo, Sosuke; Zhong, Z. H.; Park, Y. H.; Shih, Chunghao; Ozawa, Kazumi; Parish, Chad M; Meisner, Roberta Ann

    2013-01-01

    This paper reviews recent achievements as to "nuclear-grade" SiC composites in particular for materials-system integration. SiC composite component development are reviewed including VHTR control rod scale model and compact intermediate heat exchanger scale mode by current joining and assembly techniques. Joining methods for SiC to metal and results of characterization of joint shear strength by the torsion tests using small specimens were also reviewed. The recent results of neutron irradiation experiments were also reviewed including detailed analysis of mechanical properties, irradiation creep and preliminary results on tritium behavior in SiC.

  8. Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites

    SciTech Connect

    Newsome G, Snead L, Hinoki T, Katoh Y, Peters D

    2007-03-26

    The effects of fast neutron irradiation on SiC and SiC composites have been studied. The materials used were chemical vapor deposition (CVD) SiC and SiC/SiC composites reinforced with either Hi-Nicalon{trademark} Type-S, Hi-Nicalon{trademark} or Sylramic{trademark} fibers fabricated by chemical vapor infiltration. Statistically significant numbers of flexural samples were irradiated up to 4.6 x 10{sup 25} n/m{sup 2} (E>0.1 MeV) at 300, 500 and 800 C in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Dimensions and weights of the flexural bars were measured before and after the neutron irradiation. Mechanical properties were evaluated by four point flexural testing. Volume increase was seen for all bend bars following neutron irradiation. Magnitude of swelling depended on irradiation temperature and material, while it was nearly independent of irradiation fluence over the fluence range studied. Flexural strength of CVD SiC increased following irradiation depending on irradiation temperature. Over the temperature range studied, no significant degradation in mechanical properties was seen for composites fabricated with Hi-Nicalon{trademark} Type-S, while composites reinforced with Hi-Nicalon{trademark} or Sylramic fibers showed significant degradation. The effects of irradiation on the Weibull failure statistics are also presented suggesting a reduction in the Weibull modulus upon irradiation. The cause of this potential reduction is not known.

  9. Method for Forming Fiber Reinforced Composite Bodies with Graded Composition and Stress Zones

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay (Inventor); Levine, Stanley R. (Inventor); Smialek, James A. (Inventor)

    1999-01-01

    A near-net, complex shaped ceramic fiber reinforced silicon carbide based composite bodies with graded compositions and stress zones is disclosed. To provide the composite a fiber preform is first fabricated and an interphase is applied by chemical vapor infiltration, sol-gel or polymer processes. This first body is further infiltrated with a polymer mixture containing carbon, and/or silicon carbide, and additional oxide, carbide, or nitride phases forming a second body. One side of the second body is spray coated or infiltrated with slurries containing high thermal expansion and oxidation resistant. crack sealant phases and the other side of this second body is coated with low expansion phase materials to form a third body. This third body consisting of porous carbonaceous matrix surrounding the previously applied interphase materials, is then infiltrated with molten silicon or molten silicon-refractory metal alloys to form a fourth body. The resulting fourth body comprises dense composites consisting of fibers with the desired interphase which are surrounded by silicon carbide and other second phases materials at the outer and inner surfaces comprising material of silicon, germanium, refractory metal suicides, borides, carbides, oxides, and combinations thereof The resulting composite fourth body has different compositional patterns from one side to the other.

  10. Carbide/fluoride/silver self-lubricating composite

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E. (Inventor)

    1988-01-01

    A self-lubricating, friction and wear reducing composite material for use over a wide temperature spectrum from cryogenic temperature to about 900.degree. C. in a chemically reactive environment comprising silver, barium fluoride/calcium fluoride eutectic, and metal bonded chromium carbide.

  11. Carbide-fluoride-silver self-lubricating composite

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E. (Inventor)

    1987-01-01

    A self-lubricating, friction and wear reducing composite material is described for use over a wide temperature spectrum from cryogenic temperature to about 900 C in a chemically reactive environment comprising silver, barium fluoride/calcium fluoride eutectic, and metal bonded chromium carbide.

  12. Novel silicon carbide/polypyrrole composites; preparation and physicochemical properties

    SciTech Connect

    Omastova, Maria . E-mail: upolmaom@savba.sk; Boukerma, Kada; Chehimi, Mohamed M.; Trchova, Miroslava

    2005-05-18

    Novel silicon carbide/polypyrrole (SiC/PPy) conducting composites were prepared using silicon carbide as inorganic substrate. The surface modification of SiC was performed in aqueous solution by oxidative polymerization of pyrrole using ferric chloride as oxidant. Elemental analysis was used to determine the mass loading of polypyrrole in the SiC/PPy composites. Scanning electron microscopy showed the surface modification of SiC by PPy. PPy in composites was confirmed by the presence of PPy bands in the infrared spectra of SiC/PPy containing various amounts of conducting polymer. The conductivity of SiC/PPy composites depends on PPy content on the surface. The composite containing 35 wt.% PPy showed conductivity about 2 S cm{sup -1}, which is in the same range as the conductivity of pure polypyrrole powder prepared under the same conditions using the same oxidant. PPy in the composites was clearly detected by X-ray photoelectron spectroscopy (XPS) measurements by its N1s and Cl2p peaks. High resolution scans of the C1s regions distinguished between silicon carbide and polypyrrole carbons. The fraction of polypyrrole at the composite surface was estimated from the silicon and nitrogen levels. The combination of XPS and conductivity measurements suggests that the surface of the SiC/PPy composites is polypyrrole-rich for a conducting polymer mass loading of at least 12.6 wt.%.

  13. Method of preparing silicon carbide particles dispersed in an electrolytic bath for composite electroplating of metals

    DOEpatents

    Peng, Yu-Min; Wang, Jih-Wen; Liue, Chun-Ying; Yeh, Shinn-Horng

    1994-01-01

    A method for preparing silicon carbide particles dispersed in an electrolytic bath for composite electroplating of metals includes the steps of washing the silicon carbide particles with an organic solvent; washing the silicon carbide particles with an inorganic acid; grinding the silicon carbide particles; and heating the silicon carbide particles in a nickel-containing solution at a boiling temperature for a predetermined period of time.

  14. Ceramic composites reinforced with modified silicon carbide whiskers

    DOEpatents

    Tiegs, Terry N.; Lindemer, Terrence B.

    1990-01-01

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  15. Fabrication of Carbon Nanotube - Chromium Carbide Composite Through Laser Sintering

    NASA Astrophysics Data System (ADS)

    Liu, Ze; Gao, Yibo; Liang, Fei; Wu, Benxin; Gou, Jihua; Detrois, Martin; Tin, Sammy; Yin, Ming; Nash, Philip; Tang, Xiaoduan; Wang, Xinwei

    2016-03-01

    Ceramics often have high hardness and strength, and good wear and corrosion resistance, and hence have many important applications, which, however, are often limited by their poor fracture toughness. Carbon nanotubes (CNTs) may enhance ceramic fracture toughness, but hot pressing (which is one typical approach of fabricating CNT-ceramic composites) is difficult to apply for applications that require localized heat input, such as fabricating composites as surface coatings. Laser beam may realize localized material sintering with little thermal effect on the surrounding regions. However, for the typical ceramics for hard coating applications (as listed in Ref.[1]), previous work on laser sintering of CNT-ceramic composites with mechanical property characterizations has been very limited. In this paper, research work has been reported on the fabrication and characterization of CNT-ceramic composites through laser sintering of mixtures of CNTs and chromium carbide powders. Under the studied conditions, it has been found that laser-sintered composites have a much higher hardness than that for plasma-sprayed composites reported in the literature. It has also been found that the composites obtained by laser sintering of CNTs and chromium carbide powder mixtures have a fracture toughness that is ~23 % higher than the material obtained by laser sintering of chromium carbide powders without CNTs.

  16. Diamond-Silicon Carbide Composite And Method For Preparation Thereof

    DOEpatents

    Qian, Jiang; Zhao, Yusheng

    2005-09-06

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5-8 GPa, T=1400K-2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.multidot.m.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  17. Protective coating for alumina-silicon carbide whisker composites

    DOEpatents

    Tiegs, Terry N.

    1989-01-01

    Ceramic composites formed of an alumina matrix reinforced with silicon carbide whiskers homogenously dispersed therein are provided with a protective coating for preventing fracture strength degradation of the composite by oxidation during exposure to high temperatures in oxygen-containing atmospheres. The coating prevents oxidation of the silicon carbide whiskers within the matrix by sealing off the exterior of the matrix so as to prevent oxygen transport into the interior of the matrix. The coating is formed of mullite or mullite plus silicon oxide and alumina and is formed in place by heating the composite in air to a temperature greater than 1200.degree. C. This coating is less than about 100 microns thick and adequately protects the underlying composite from fracture strength degradation due to oxidation.

  18. Characterization of carbides composite surface layers produced by PTA

    NASA Astrophysics Data System (ADS)

    Tajoure, M.; Tajouri, A.

    2015-03-01

    Composite surface layer of nickel base with titanium carbide in powder form was deposited on to surface of low alloy steel 18G2A type according to polish standard by using plasma transferred arc technique. Results showed that, plasma transferred arc hardfacin process was successfully conducted by using PMNICr50P alloy plus titanium carbide powders. Maximum hardness of 754 HV and minimum dilution of 4.6 % were achieved by using an arc current of 80 A. However, when the current was further increased to 120 A& the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base with titanium carbide feature uniform distribution of reinforcement particles with irregular grain shape and relatively small particles size, and regular boundary line between the substrate and over layer with presence of black area along the boundary line. A few micro - porosities are located in the matrix.

  19. Method for making hot-pressed fiber-reinforced carbide-graphite composite

    DOEpatents

    Riley, Robert E.; Wallace Sr., Terry C.

    1979-01-01

    A method for the chemical vapor deposition of a uniform coating of tantalum metal on fibers of a woven graphite cloth is described. Several layers of the coated cloth are hot pressed to produce a tantalum carbide-graphite composite having a uniformly dispersed, fine grained tantalum carbide in graphite with compositions in the range of 15 to 40 volume percent tantalum carbide.

  20. Method of making carbide/fluoride/silver composites

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E. (Inventor); Dellacorte, Christopher (Inventor)

    1991-01-01

    A composition containing 30 to 70 percent chromium carbide, 5 to 20 percent soft noble metal, 5 to 20 percent metal fluorides, and 20 to 60 percent metal binder is used in a powdered metallurgy process for the production of self-lubricating components, such as bearings. The use of the material allows the self-lubricating bearing to maintain its low friction properties over an extended range of operating temperatures.

  1. Fatigue of alumina-based ceramics and chrome carbide composites

    NASA Astrophysics Data System (ADS)

    Kireitseu, Maksim V.; Yerakhavets, Liudmila; Nemerenco, Ion; Basenuk, Vladimir L.

    2003-10-01

    The paper was revealed a fatigue in the alumina-chrome carbide composite. The trapped crack front resembles a collinear array of microcracks interspersed by grains rich in transformable precipitates. This micromechanical model provides a reasonable explanation for the observed fatigue crack growth. A numerical procedure similar to the one used in the analysis of the array of collinear cracks, based on complex potentials and dislocation formalism is also used to simulate fatigue of composite coatings based on oxide ceramics and chrome carbide. Assuming power-law crack growth, it is found that the crack growth rate decreases with the applied stress intensity factor in the initial stage of fatigue crack growth. Depending on the applied load and the amount of transformation, the growth rate either goes through a minimum before increasing to the normal crack regime, or the rate continues to decrease until the crack is arrested. A detailed parametric study of the phenomenon of fatigue crack arrest in composite coatings based on oxide ceramics and chrome carbide reveals that the combination of transformation strength parameter and applied load determines whether or not crack arrest will occur, irrespective of the initial crack length. Based on the parametric study a simple linear relationship between the applied load and the minimum transformation strength parameter necessary to cause crack arrest has been developed. it will be found useful in the design against fatigue by predicting the maximum toad at which crack arrest can be expected.

  2. Thermal properties of wood-derived silicon carbide and copper-silicon carbide composites

    NASA Astrophysics Data System (ADS)

    Pappecena, Kristen E.

    Wood-derived ceramics and composites have been of interest in recent years due to their unique microstructures, which lead to tailorable properties. The porosity and pore size distribution of each wood type is different, which yields variations in properties in the resultant materials. The thermal properties of silicon carbide ceramics and copper-silicon carbide composites derived from wood were studied as a function of their pore structures. Wood was pyrolyzed at temperatures ranging from 300-2400°C to yield porous carbon. The progression toward long-range order was studied as a function of pyrolyzation temperature. Biomorphic silicon carbide (bioSiC) is a porous ceramic material resulting from silicon melt infiltration of these porous carbon materials. BioSiC has potential applicability in many high temperature environments, particularly those in which rapid temperature changes occur. To understand the behavior of bioSiC at elevated temperatures, the thermal and thermo-mechanical properties were studied. The thermal conductivity of bioSiC from five precursors was determined using flash diffusivity at temperatures up to 1100°C. Thermal conductivity results varied with porosity, temperature and orientation, and decreased from 42-13 W/mK for porosities of 43-69%, respectively, at room temperature. The results were compared with to object-oriented finite-element analysis (OOF). OOF was also used to model and understand the heat-flow paths through the complex bioSiC microstructures. The thermal shock resistance of bioSiC was also studied, and no bioSiC sample was found to fail catastrophically after up to five thermal shock cycles from 1400°C to room temperature oil. Copper-silicon carbide composites have potential uses in thermal management applications due to the high thermal conductivity of each phase. Cu-bioSiC composites were created by electrodeposition of copper into bioSiC pores. The detrimental Cu-SiC reaction was avoided by using this room temperature

  3. Status of silicon carbide composites for fusion

    SciTech Connect

    Snead, L.L.; Jones, R.H.; Kohyama, A.

    1996-04-01

    An effort is now underway to design an irradiation creep experiment involving SiC composites and SiC fibers. In order to successfully design such an experiment, it is necessary to review and assess the available data for monolithic SiC to establish the possible bounds of creep behavior for the composite. The data available show that monolithic SiC will indeed creep at a higher rate under irradiation compared to that of thermal creep, and surprisingly, it will do so in a temperature-dependant manner that is typical of metals.

  4. Carbide coated fibers in graphite-aluminum composites

    NASA Technical Reports Server (NTRS)

    Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

    1975-01-01

    The NASA-supported program at the Los Alamos Scientific Laboratory (LASL) to develop carbon fiber-aluminum matrix composites is described. Chemical vapor deposition (CVD) was used to uniformly deposit thin, smooth, continuous coats of TiC on the fibers of graphite tows. Wet chemical coating of fibers, followed by high-temperature treatment, was also used, but showed little promise as an alternative coating method. Strength measurements on CVD coated fiber tows showed that thin carbide coats can add to fiber strength. The ability of aluminum alloys to wet TiC was successfully demonstrated using TiC-coated graphite surfaces. Pressure-infiltration of TiC- and ZrC-coated fiber tows with aluminum alloys was only partially successful. Experiments were performed to evaluate the effectiveness of carbide coats on carbon as barriers to prevent reaction between alluminum alloys and carbon. Initial results indicate that composites of aluminum and carbide-coated graphite are stable for long periods of time at temperatures near the alloy solidus.

  5. Dynamic consolidation of aluminum-silicon carbide composites

    SciTech Connect

    Rabin, B.H.; Korth, G.E.; Williamson, R.L.

    1990-01-01

    Dynamic consolidation was investigated as a potential method for producing P/M metal matrix composites. In this study, 2124 aluminum powders were mixed with silicon carbide particulate and consolidated using explosives. Numerical simulations were performed to provide insight into the consolidation process and to aid in the selection of experimental conditions. The microstructure of the as-consolidated product was dependent upon processing variables. Careful control of the shock parameters allowed full density, crack free composites to be achieved in cylindrical geometries. Although full density was obtained, low fracture strengths suggested a lack of interparticle bonding, probably resulting from the limited ability to redistribute surface oxides during consolidation. 10 refs., 9 figs.

  6. Carbide coated fibers in graphite-aluminum composites

    NASA Technical Reports Server (NTRS)

    Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

    1975-01-01

    Thin, uniform coats of titanium carbide, deposited on graphite fibers by chemical vapor deposition with thicknesses up to approximately 0.1 microns were shown to improve fiber strength significantly. For greater thicknesses, strength was degraded. The coats promote wetting of the fibers and infiltration of the fiber yarns with aluminum alloys, and act as protective barriers to inhibit reaction between the fibers and the alloys. Chemical vapor deposition was used to produce silicon carbide coats on graphite fibers. In general, the coats were nonuniform and were characterized by numerous surface irregularities. Despite these irregularities, infiltration of these fibers with aluminum alloys was good. Small graphite-aluminum composite samples were produced by vacuum hot-pressing of aluminum-infiltrated graphite yarn at temperatures above the metal liquidus.

  7. Method of making silicon carbide-silicon composite having improved oxidation resistance

    NASA Technical Reports Server (NTRS)

    Luthra, Krishan Lal (Inventor); Wang, Hongyu (Inventor)

    2002-01-01

    A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

  8. Silicon carbide-silicon composite having improved oxidation resistance and method of making

    NASA Technical Reports Server (NTRS)

    Luthra, Krishan Lal (Inventor); Wang, Hongyu (Inventor)

    1999-01-01

    A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

  9. Oxidation Behavior of Carbon Fiber Reinforced Silicon Carbide Composites

    NASA Technical Reports Server (NTRS)

    Valentin, Victor M.

    1995-01-01

    Carbon fiber reinforced Silicon Carbide (C-SiC) composites offer high strength at high temperatures and good oxidation resistance. However, these composites present some matrix microcracks which allow the path of oxygen to the fiber. The aim of this research was to study the effectiveness of a new Silicon Carbide (SiC) coating developed by DUPONT-LANXIDE to enhance the oxidation resistance of C-SiC composites. A thermogravimetric analysis was used to determine the oxidation rate of the samples at different temperatures and pressures. The Dupont coat proved to be a good protection for the SiC matrix at temperatures lower than 1240 C at low and high pressures. On the other hand, at temperatures above 1340 C the Dupont coat did not seem to give good protection to the composite fiber and matrix. Even though some results of the tests have been discussed, because of time restraints, only a small portion of the desired tests could be completed. Therefore, no major conclusions or results about the effectiveness of the coat are available at this time.

  10. Fatigue behavior of continuous fiber silicon-carbide-aluminum composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Wallis, R. R.

    1984-01-01

    Four lay-ups of continuous fiber silicon carbide (SCS2) fiber/aluminum matrix composites were tested to assess fatigue mechanisms including stiffness loss when cycled below their respective fatigue limits. The lay-ups were 0 (sub 8), 0(sub 2)/ + or - 45 (sub 2s), 0/90 (sub 2s),and 0/ + or 45/90 (subs). The data were compared with predictions from the author's previously published shakedown model which predicts fatigue-induced stiffness loss in metal matrix composites. A fifth lay-up, + or - 45 (sub 2s), was tested to compare shakedown and fatigue limits. The particular batch of silicon-carbide fibers tested in this program had a somewhat lower modulus (340 GPa) than expected and displayed poor bonding to the aluminum matrix. Good agreement was obtained between the stiffness loss model and the test data. The fatigue damage below the fatigue limit was primarily in the form of matrix cracking. The fatigue limit corresponded to the laminate shakedown for the + or - 45 (sub 2s) laminate.

  11. Formation Mechanism of Titanium Carbide Crystal in Laser Synthesized Metal-Ceramic Composite Coating

    NASA Astrophysics Data System (ADS)

    Du, Baoshuai; Zhang, Zhongwen; Wang, Xinhong; Zou, Zengda

    In situ titanium carbide reinforced iron-based composite coating was deposited on mild carbon steel using laser surface engineering (LSE) with ferrotitanium and graphite as precursor. The microstructure and phase constituents of the deposited coating were characterized. Formation mechanism of titanium carbide crystal in the composite coating was elucidated by correlating the morphology of titanium carbide and the thermal cycle experienced by the precursor during the laser treatment. It was demonstrated that titanium carbide was formed in situ as a result of the metallurgical reaction between ferrotitanium and graphite following a liquid-precipitation route. Different morphologies of titanium carbide crystal (dendrite and fishbone) correspond to the primary and eutectic titanium carbide respectively.

  12. Enhanced Sintering of Boron Carbide-Silicon Composites by Silicon

    NASA Astrophysics Data System (ADS)

    Zeng, Xiaojun; Liu, Weiliang

    2016-09-01

    Boron carbide (B4C)-silicon (Si) composites have been prepared by aqueous tape casting, laminating, and spark plasma sintering (SPS). The influences of silicon (Si) content on the phases, microstructure, sintering properties, and mechanical properties of the obtained B4C-Si composites are studied. The results indicate that the addition of Si powder can act as a sintering aid and contribute to the sintering densification. The addition of Si powder can also act as a second phase and contribute to the toughening for composites. The relative density of B4C-Si composites samples with adding 10 wt.% Si powder prepared by SPS at 1600 °C and 50 MPa for 8 min is up to 98.3%. The bending strength, fracture toughness, and Vickers hardness of the sintered samples are 518.5 MPa, 5.87 MPa m1/2, and 38.9 GPa, respectively. The testing temperature-dependent high-temperature bending strength and fracture toughness can reach a maximum value at 1350 °C. The B4C-Si composites prepared at 1600, 1650, and 1700 °C have good high-temperature mechanical properties. This paper provides a facile low-temperature sintering route for B4C ceramics with improved properties.

  13. Rapid Fabrication of Carbide Matrix/Carbon Fiber Composites

    NASA Technical Reports Server (NTRS)

    Williams, Brian E.; Bernander, Robert E.

    2007-01-01

    Composites of zirconium carbide matrix material reinforced with carbon fibers can be fabricated relatively rapidly in a process that includes a melt infiltration step. Heretofore, these and other ceramic matrix composites have been made in a chemical vapor infiltration (CVI) process that takes months. The finished products of the CVI process are highly porous and cannot withstand temperatures above 3,000 F (approx.1,600 C). In contrast, the melt-infiltration-based process takes only a few days, and the composite products are more nearly fully dense and have withstood temperatures as high as 4,350 F (approx.2,400 C) in a highly oxidizing thrust chamber environment. Moreover, because the melt- infiltration-based process takes much less time, the finished products are expected to cost much less. Fabrication begins with the preparation of a carbon fiber preform that, typically, is of the size and shape of a part to be fabricated. By use of low-temperature ultraviolet-enhanced chemical vapor deposition, the carbon fibers in the preform are coated with one or more interfacial material(s), which could include oxides. The interfacial material helps to protect the fibers against chemical attack during the remainder of the fabrication process and against oxidation during subsequent use; it also enables slippage between the fibers and the matrix material, thereby helping to deflect cracks and distribute loads. Once the fibers have been coated with the interfacial material, the fiber preform is further infiltrated with a controlled amount of additional carbon, which serves as a reactant for the formation of the carbide matrix material. The next step is melt infiltration. The preform is exposed to molten zirconium, which wicks into the preform, drawn by capillary action. The molten metal fills most of the interstices of the preform and reacts with the added carbon to form the zirconium carbide matrix material. The zirconium does not react with the underlying fibers because they

  14. Spark plasma sintering of tantalum carbide and graphene reinforced tantalum carbide composites

    NASA Astrophysics Data System (ADS)

    Kalluri, Ajith Kumar

    Tantalum carbide (TaC), an ultra-high temperature ceramic (UHTC), is well known for its exceptional properties such as high hardness (15-19 GPa), melting point (3950 °C), elastic modulus (537 GPa), chemical resistance, and thermal shock resistance. To make TaC to be the future material for hypersonic vehicles, it is required to improve its thermal conductivity, strength, and fracture toughness. Researchers have previously reinforced TaC ceramic with carbides of silicon and boron as well as carbon nanotubes (CNTs), however, these reinforcements either undergo chemical changes or induce defects in the matrix during processing. In addition, these reinforcements exhibit a very minimal improvement in the properties. In the present work, we attempted to improve TaC fracture toughness by reinforcing with graphene nano-platelets (GNPs) and processing through spark plasma sintering at high temperature of 2000 °C, pressure of 70 MPa, and soaking time of 10 min. In addition, we investigated the active densification mechanism during SPS of TaC powder and the effect of ball milling time on mechanical properties of sintered TaC. A relative density of >96% was achieved using SPS of monolithic TaC (<3 μm). Ball milling improved the sintering kinetics and improved the mechanical properties (microhardness, bi-axial flexural strength, and indentation fracture toughness). Activation energy (100 kJ/mol) and stress exponent (1.2) were obtained using the analytical model developed for power-law creep. Grain boundary sliding is proposed as active densification mechanism based on these calculations. Reinforcing GNPs (2-6 vol.% ) in the TaC matrix improved relative density (99.8% for TaC-6 vol.% GNP). Also ˜150% and ˜180% increase in flexural strength and fracture toughness, respectively, was observed for TaC-6 vol.% GNP composite. The significant improvement in these properties is attributed to improved densification and toughening mechanisms such as sheet pull-out and crack

  15. Thermal stress analysis of a silicon carbide/aluminum composite

    NASA Technical Reports Server (NTRS)

    Gdoutos, E. E.; Karalekas, D.; Daniel, I. M.

    1991-01-01

    Thermal deformations and stresses were studied in a silicon-carbide/aluminum filamentary composite at temperatures up to 370 C (700 F). Longitudinal and transverse thermal strains were measured with strain gages and a dilatometer. An elastoplastic micromechanical analysis based on a one-dimensional rule-of-mixtures model and an axisymmetric two-material composite cylinder model was performed. It was established that beyond a critical temperature thermal strains become nonlinear with decreasing longitudinal and increasing transverse thermal-expansion coefficients. This behavior was attributed to the plastic stresses in the aluminum matrix above the critical temperature. An elastoplastic analysis of both micromechanical models was performed to determine the stress distributions and thermal deformation in the fiber and matrix of the composite. While only axial stresses can be determined by the rule-of-mixtures model, the complete triaxial state of stress is established by the composite cylinder model. Theoretical predictions for the two thermal-expansion coefficients were in satisfactory agreement with experimental results.

  16. Advanced Measurements of Silicon Carbide Ceramic Matrix Composites

    SciTech Connect

    Farhad Farzbod; Stephen J. Reese; Zilong Hua; Marat Khafizov; David H. Hurley

    2012-08-01

    Silicon carbide (SiC) is being considered as a fuel cladding material for accident tolerant fuel under the Light Water Reactor Sustainability (LWRS) Program sponsored by the Nuclear Energy Division of the Department of Energy. Silicon carbide has many potential advantages over traditional zirconium based cladding systems. These include high melting point, low susceptibility to corrosion, and low degradation of mechanical properties under neutron irradiation. In addition, ceramic matrix composites (CMCs) made from SiC have high mechanical toughness enabling these materials to withstand thermal and mechanical shock loading. However, many of the fundamental mechanical and thermal properties of SiC CMCs depend strongly on the fabrication process. As a result, extrapolating current materials science databases for these materials to nuclear applications is not possible. The “Advanced Measurements” work package under the LWRS fuels pathway is tasked with the development of measurement techniques that can characterize fundamental thermal and mechanical properties of SiC CMCs. An emphasis is being placed on development of characterization tools that can used for examination of fresh as well as irradiated samples. The work discuss in this report can be divided into two broad categories. The first involves the development of laser ultrasonic techniques to measure the elastic and yield properties and the second involves the development of laser-based techniques to measurement thermal transport properties. Emphasis has been placed on understanding the anisotropic and heterogeneous nature of SiC CMCs in regards to thermal and mechanical properties. The material properties characterized within this work package will be used as validation of advanced materials physics models of SiC CMCs developed under the LWRS fuels pathway. In addition, it is envisioned that similar measurement techniques can be used to provide process control and quality assurance as well as measurement of

  17. Ultrafine-grained Aluminm and Boron Carbide Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Vogt, Rustin

    Cryomilling is a processing technique used to generate homogenously distributed boron carbide (B4C) particulate reinforcement within an ultrafine-grained aluminum matrix. The motivation behind characterizing a composite consisting of cryomilled aluminum B4C metal matrix composite is to design and develop a high-strength, lightweight aluminum composite for structural and high strain rate applications. Cryomilled Al 5083 and B4C powders were synthesized into bulk composite by various thermomechanical processing methods to form plate and extruded geometries. The effects of processing method on microstructure and mechanical behavior for the final consolidated composite were investigated. Cryomilling for extended periods of time in liquid nitrogen has shown to increase strength and thermal stability. The effects associated with cryomilling with stearic acid additions (as a process-control agent) on the degassing behavior of Al powders is investigated and results show that the liberation of compounds associated with stearic acid were suppressed in cryomilled Al powders. The effect of thermal expansion mismatch strain on strengthening due to geometrically necessary dislocations resulting from quenching is investigated and found not to occur in bulk cryomilled Al 5083 and B 4C composites. Previous cryomilled Al 5083 and B4C composites have exhibited ultrahigh strength associated with considerable strain-to-failure (>14 pct.) at high strain rates (>103/s) during mechanical testing, but only limited strain-to-failure (˜0.75 pct.) at quasi-static strain rates (10-3/s). The increased strain to failure at high strain rates is attributed to micro-flaw developments, including kinking, extensive axial splitting, and grain growth were observed after high strain rate deformation, and the significance of these mechanisms is considered.

  18. Body Composition Tests

    MedlinePlus

    ... more bone and muscle will weigh more in water than a person with less bone and muscle. The volume of the body is calculated and body density and body fat percentage are calculated. This technique ...

  19. Body composition in detoxified alcoholics.

    PubMed

    York, J L; Pendergast, D E

    1990-04-01

    Body composition was evaluated in healthy detoxified alcoholics (aged 20-39) and lifestyle controls, with the expectation that prolonged, excessive consumption of alcohol may bring about nutritional or toxicologic alterations in the relationship between body fat and lean body mass. Body fat was assessed by measurements of skin-fold thickness and by means of bioelectric impedance methodology. No noteworthy differences were observed between alcoholics and controls with regard to the relationship between lean body mass and body fat or in the relationship between extracellular and intracellular water. It would appear that 15-20 years of heavy alcohol consumption does not necessarily alter body composition in healthy, young alcoholics.

  20. Affordable Fabrication and Properties of Silicon Carbide-Based Interpenetrating Phase Composites

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay

    1998-01-01

    An affordable processing technique for the fabrication of silicon carbide-based interpenetrating phase composites (IPCs) is presented. This process consists of the production of microporous carbon preforms and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture for which methods to control pore volume and pore size have been established. The process gives good control of microstructure and morphology of silicon carbide-based composite materials. Room and high temperature mechanical properties (flexural strength, compressive strength, and flexural creep) of low and high silicon-silicon carbide composites will be discussed.

  1. METHOD FOR FORMING A COATING OF MOLYBDENUM CARBIDE ON A CARBON BODY

    DOEpatents

    Simnad, M.T.

    1962-04-01

    A method is described for coating a carbon bodywith molybdenum carbide in such a manner that the carbon body is rendered less permeable to the flow of gases and has increased resistance to corrosion and erosion. The method includes coating a carbon body with molybdenum trioxide by contacting it at a temperature below the condensation temperature with molybdenum trioxide vapors and thereafter carburizing the molybdenum trioxide in situ in an inert atmosphere on the carhon body. (AEC)

  2. Interfacial preferential dissolution on silicon carbide particulate/aluminum composites

    SciTech Connect

    Yao, H.Y.; Zhu, R.Z.

    1998-07-01

    Previous studies on corrosion of discontinuously reinforced aluminum alloy composites have assumed that the role of the reinforcement-matrix interface is merely as a preferable site for pitting. In this work, the interfacial preferential dissolution (IPD) occurring on silicon carbide particulate/aluminum (SiC{sub p}/Al) composites in a medium of aqueous sodium chloride (NaCl) solution was studied. IPD was quite distinct from pitting. IPD occurred on the composites with either a pure aluminum matrix or an aluminum alloy Al 2024 (UNS A92024) matrix, whether they were fabricated by a cast process or by a powder metallurgy process. In the light of elastoplastic mechanics, the width of the plastically deformed zone around SiC particles (created by the contraction misfit between SiC particles and the matrix during quenching) was deduced to be 0.5 D, where D is the diameter of the SiC particles. This was in agreement with the measured width of the IPD region (0.3 D to 0.4 D). It was concluded that IPD was caused by the poor integrity of the surface oxide film upon the plastically deformed zone near the interface and was independent of the chemical, metallurgical, and galvanic coupling factors around the interface, if any. A copper-deposition experiment indicated this poor integrity. IPD caused increased dissolution at SiC clusters and uniform corrosion for the composites with high SiC content. Moreover, IPD and pitting suppressed each other by a means of cathodic protection.

  3. Priority compositions of boron carbide crystals obtained by self-propagating high-temperature synthesis

    NASA Astrophysics Data System (ADS)

    Ponomarev, V. I.; Konovalikhin, S. V.; Kovalev, I. D.; Vershinnikov, V. I.

    2015-09-01

    Splitting of reflections from boron carbide has been found for the first time by an X-ray diffraction study of polycrystalline mixture of boron carbide В15- х С х , (1.5 ≤ x ≤ 3) and its magnesium derivative C4B25Mg1.42. An analysis of reflection profiles shows that this splitting is due to the presence of boron carbide phases of different compositions in the sample, which are formed during crystal growth. The composition changes from В12.9С2.1 to В12.4С2.6.

  4. Body composition in clinical practice.

    PubMed

    Andreoli, Angela; Garaci, Francesco; Cafarelli, Francesco Pio; Guglielmi, Giuseppe

    2016-08-01

    Nutritional status is the results of nutrients intake, absorption and utilization, able to influence physiological and pathological conditions. Nutritional status can be measured for individuals with different techniques, such as CT Body Composition, quantitative Magnetic Resonance Imaging, Ultrasound, Dual-Energy X-Ray Absorptiometry and Bioimpendance. Because obesity is becoming a worldwide epidemic, there is an increasing interest in the study of body composition to monitor conditions and delay in development of obesity-related diseases. The emergence of these evidence demonstrates the need of standard assessment of nutritional status based on body weight changes, playing an important role in several clinical setting, such as in quantitative measurement of tissues and their fluctuations in body composition, in survival rate, in pathologic condition and illnesses. Since body mass index has been shown to be an imprecise measurement of fat-free and fat mass, body cell mass and fluids, providing no information if weight changes, consequently there is the need to find a better way to evaluate body composition, in order to assess fat-free and fat mass with weight gain and loss, and during ageing. Monitoring body composition can be very useful for nutritional and medical interventional. This review is focused on the use of Body Composition in Clinical Practice.

  5. Low Cost Fabrication of Silicon Carbide Based Ceramics and Fiber Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Singh, M.; Levine, S. R.

    1995-01-01

    A low cost processing technique called reaction forming for the fabrication of near-net and complex shaped components of silicon carbide based ceramics and composites is presented. This process consists of the production of a microporous carbon preform and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture with very good control of pore volume and pore size thereby yielding materials with tailorable microstructure and composition. Mechanical properties (elastic modulus, flexural strength, and fracture toughness) of reaction-formed silicon carbide ceramics are presented. This processing approach is suitable for various kinds of reinforcements such as whiskers, particulates, fibers (tows, weaves, and filaments), and 3-D architectures. This approach has also been used to fabricate continuous silicon carbide fiber reinforced ceramic composites (CFCC's) with silicon carbide based matrices. Strong and tough composites with tailorable matrix microstructure and composition have been obtained. Microstructure and thermomechanical properties of a silicon carbide (SCS-6) fiber reinforced reaction-formed silicon carbide matrix composites are discussed.

  6. Gonadotropin excretion and body composition.

    PubMed

    Penny, R; Goldstein, I P; Frasier, S D

    1978-02-01

    Urinary follicle stimulating hormone (FSH) and luteinizing hormone (LH) excretion was correlated with calculated total body water (TBW) and body fat (BF) in 140 normal girls and 142 normal boys, ages 3 to 16 years. In girls, there was a significant increase in gonadotropin excretion at the time of a significant increase in BF as a percent of body weight and decrease in TBW as a percent of body weight. Pubertal changes in body composition were seen in girls at the same chronological age and stage of puberty as increased gonadotropin excretion. Similar findings were observed in boys. Pubertal changes in body composition (an increase in TBW as a percent of body weight and decrease of BF as a percent of body weight) accompanied significantly increased gonadotropin excretion. Both developmental changes were seen at the same chronological age and stage of puberty. Our findings are consistent with the hypothesis that characteristic changes in body composition as well as the other hallmarks of puberty, including menarche in girls, result from increased gonadotropin and gonadal steroid secretion. They do not support the hypothesis that changes of body composition trigger increased hypothalamic function and hormone secretion leading to the subsequent events of puberty. PMID:634687

  7. Rim region growth and its composition in reaction bonded boron carbide composites with core-rim structure

    NASA Astrophysics Data System (ADS)

    Hayun, S.; Weizmann, A.; Dilman, H.; Dariel, M. P.; Frage, N.

    2009-06-01

    Aluminum was detected in reaction-bonded boron carbide that had been prepared by pressureless infiltration of boron carbide preforms with molten silicon in a graphite furnace under vacuum. The presence of Al2O3 in the heated zone, even though not in contact with the boron carbide preform, stands behind the presence of aluminium in the rim region that interconnects the initial boron carbide particles. The composition of the rim corresponds to the Bx(C,Si,Al)y quaternary carbide phase. The reaction of alumina with graphite and the formation of a gaseous aluminum suboxide (Al2O) accounts for the transfer of aluminum in the melt and, subsequently in the rim regions. The presence of Al increases the solubility of boron in liquid silicon, but with increasing aluminum content the activity of boron decreases. These features dominate the structural evolution of the rim-core in the presence of aluminum in the melt.

  8. Evaluation of titanium carbide metal matrix composites deposited via laser cladding

    NASA Astrophysics Data System (ADS)

    Cavanaugh, Daniel Thomas

    Metal matrix composites have been widely studied in terms of abrasion resistance, but a particular material system may behave differently as particle size, morphology, composition, and distribution of the hardening phase varies. The purpose of this thesis was to understand the mechanical and microstructural effects of combining titanium carbide with 431 series stainless steel to create a unique composite via laser cladding, particularly regarding wear properties. The most predominant effect in increasing abrasion resistance, measured via ASTM G65, was confirmed to be volume fraction of titanium carbide addition. Macrohardness was directly proportional to the amount of carbide, though there was an overall reduction in individual particle microhardness after cladding. The reduction in particle hardness was obscured by the effect of volume fraction carbide and did not substantially contribute to the wear resistance changes. A model evaluating effective mean free path of the titanium carbide particles was created and correlated to the measured data. The model proved successful in linking theoretical mean free path to overall abrasion resistance. The effects of the titanium carbide particle distributions were limited, while differences in particle size were noticeable. The mean free path model did not correlate well with the particle size, but it was shown that the fine carbides were completely removed by the coarse abrasive particles in the ASTM G65 test. The particle morphology showed indications of influencing the wear mode, but no statistical reduction was observed in the volume loss figures. Future studies may more specifically focus on particle morphology or compositional effects of the carbide particles.

  9. Alumina-zirconia-silicon carbide-magnesia compositions and articles made through therefrom

    SciTech Connect

    Mehrotra, P.K.; Billman, E.R.

    1990-10-23

    This patent describes an alumina based ceramic composition. It comprises: about 1.5 to 17.5 v/o silicon carbide whiskers; about 5 to 17.5 v/o zirconia; a residue of a magnesia addition added in the amount of about 0.03 to 3 v/o; alumina forming essentially the remainder of the composition; wherein the silicon carbide whiskers, the zirconia and the residue of the magnesia addition are substantially homo-geneously dispersed in a matrix formed of the alumina; and wherein at least about 4.0 v/o of the ceramic composition is tetragonal zirconia.

  10. Composition optimization of self-lubricating chromium carbide-based composite coatings for use to 760 deg C

    NASA Technical Reports Server (NTRS)

    Dellacorte, C.; Sliney, H. E.

    1986-01-01

    This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a ternary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760 C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

  11. Composition optimization of self-lubricating chromium-carbide-based composite coatings for use to 760 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Chris; Sliney, Harold E.

    1987-01-01

    This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a ternary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760 C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

  12. Composition optimization of self-lubricating chromium carbide-based composite coatings for use to 760/sup 0/C

    SciTech Connect

    DellaCorte, C.; Sliney, H.E.

    1986-01-01

    This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the ''base stock'' because of the known excellent wear resistance and the chemical stability of chromium carbide. ''Additives'' were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a termary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto a superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760/sup 0/C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

  13. Body composition in healthy aging.

    PubMed

    Baumgartner, R N

    2000-05-01

    Health risks in elderly people cannot be evaluated simply in conventional terms of body fatness or fat distribution. Elderly people have less muscle and bone mass, expanded extracellular fluid volumes, and reduced body cell mass compared to younger adults. These nonfat components of body composition play critical roles, influencing cognitive and physical functional status, nutritional and endocrine status, quality of life, and comorbidity in elderly people. Different patterns of "disordered body composition" have different relationships to these outcomes and may require different, tailored approaches to treatment that combine various exercise regimens and dietary supplements with hormone replacement or appetite-stimulating drugs. Skeletal muscle atrophy, or "sarcopenia," is highly prevalent in the elderly population, increases with age, and is strongly associated with disability, independent of morbidity. Elders at greatest risk are those who are simultaneously sarcopenic and obese. The accurate identification of sarcopenic obesity requires precise methods of simultaneously measuring fat and lean components, such as dual-energy X-ray absorptiometry.

  14. Deformation of an alumina-zirconia-silicon carbide-whisker reinforced composite

    SciTech Connect

    Calderon-Moreno, J.M.; DeArellano-Lopez, A.R.; Dominguez-Rodriguez, A.; Routbort, J.L.; Leasky, T.

    1993-04-01

    Alumina-zirconia composites (MERC) with the addition of 0 and 28 vol % of silicon carbide whiskers have been deformed under compression at constant rate at 1450C, in air. Mechanical results are compared with the behavior of a commercial alumina (ARCO) with analogous proportions of silicon carbide-whiskers (0 and 30 vol %), under the same testing conditions. Flow stresses are typically higher for ARCO materials than for MERC materials. The addition of SiC whiskers increases flow stresses in ARCO composites, and decreases them for MERC samples. Microstructural observations confirm that the change in flow stress is the result of the presence of a glass phase in the MERC samples.

  15. Enhancement of the thermal properties of silver-diamond composites with chromium carbide coating

    NASA Astrophysics Data System (ADS)

    Tang, Yanxia; Wang, Lihua; Zhao, Chao

    2014-05-01

    The present work reports the enhancement of the thermal properties in Ag/diamond matrix composites reinforced with chromium carbide coated diamond particles. The coated diamond particles were characterized by x-ray diffraction, x-ray photoelectron spectroscopy and Raman spectra. The composites were synthesized by spark plasma sintering. The chromium carbide coating on the diamond particles resulted in composites exhibiting improved wettability and strong interfacial bonding between the diamond particles and Ag matrix. The composites with coated diamonds showed a low coefficient of thermal expansion of 8.24 × 10-6/K and a high thermal conductivity of 695 W/mK at 60 % particle volume fraction, which greatly outperformed the composites with uncoated diamonds at the same particle volume fraction. The obtained results are useful for synthesizing Ag/diamond composites with greatly improved thermal performance.

  16. Processing and mechanical properties of aluminium-silicon carbide metal matrix composites

    NASA Astrophysics Data System (ADS)

    Nuruzzaman, D. M.; Kamaruzaman, F. F. B.

    2016-02-01

    In this study, aluminium-silicon carbide (Al-SiC) metal matrix composites (MMCs) of different compositions were prepared under different compaction loads. Three different types Al-SiC composite specimens having 10%, 20% and 30% volume fractions of silicon carbide were fabricated using conventional powder metallurgy (PM) route. The specimens of different compositions were prepared under different compaction loads 10 ton and 15 ton. The effect of volume fraction of SiC particulates and compaction load on the properties of Al/SiC composites were investigated. The obtained results show that density and hardness of the composites are greatly influenced by volume fraction of silicon carbide particulates. Results also show that density, hardness and microstructure of Al-SiC composites are significantly influenced depending on the compaction load. The increase in the volume fraction of SiC enhances the density and hardness of the Al/SiC composites. For 15 ton compaction load, the composites show increased density and hardness as well as improved microstructure than the composites prepared under 10 ton compaction load. Furthermore, optical micrographs reveal that SiC particulates are uniformly distributed in the Al matrix.

  17. Priority compositions of boron carbide crystals obtained by self-propagating high-temperature synthesis

    SciTech Connect

    Ponomarev, V. I. Konovalikhin, S. V.; Kovalev, I. D.; Vershinnikov, V. I.

    2015-09-15

    Splitting of reflections from boron carbide has been found for the first time by an X-ray diffraction study of polycrystalline mixture of boron carbide B{sub 15–x}C{sub x}, (1.5 ≤ x ≤ 3) and its magnesium derivative C{sub 4}B{sub 25}Mg{sub 1.42}. An analysis of reflection profiles shows that this splitting is due to the presence of boron carbide phases of different compositions in the sample, which are formed during crystal growth. The composition changes from B{sub 12.9}C{sub 2.1} to B{sub 12.4}C{sub 2.6}.

  18. Aluminum nitride-silicon carbide whisker composites: Processing, properties, and microstructural stability

    SciTech Connect

    Cross, M.T.

    1990-01-01

    Aluminum nitride -- silicon carbide whisker composites with up to 20 vol % whiskers were fabricated by pressureless sintering (1750{degree}--1800{degree}C) and by hot-pressing (1700{degree}--1800{degree}C). Silicon carbide whiskers were found to degrade depending on the type of protective powder bed used during sintering. Whiskers were found to degraded in high oxygen containing samples by reaction with sintering additives. Whisker degradation was also due to the formation of silicon carbide -- aluminum nitride solid solution. No whisker degradation was observed in hot-pressed samples. For these samples Young's modulus and fracture toughness were measured. A 33% increase in the fracture toughness was measured by the indentation technique for a 20 vol % whisker composite. Operative toughening mechanisms were investigated using scanning electron microscopy. Crack deflection and whisker bridging were the dominant mechanisms. It was also shown that load transfer from matrix to whiskers can be a contributing factor to toughening. 88 refs., 34 figs., 11 tabs.

  19. Machining studies of die cast aluminum alloy-silicon carbide composites

    NASA Astrophysics Data System (ADS)

    Sornakumar, Thambu; Kathiresan, Marimuthu

    2010-10-01

    Metal matrix composites (MMCs) with high specific stiffness, high strength, improved wear resistance, and thermal properties are being increasingly used in advanced structural, aerospace, automotive, electronics, and wear applications. Aluminum alloy-silicon carbide composites were developed using a new combination of the vortex method and the pressure die-casting technique in the present work. Machining studies were conducted on the aluminum alloy-silicon carbide (SiC) composite work pieces using high speed steel (HSS) end-mill tools in a milling machine at different speeds and feeds. The quantitative studies on the machined work piece show that the surface finish is better for higher speeds and lower feeds. The surface roughness of the plain aluminum alloy is better than that of the aluminum alloy-silicon carbide composites. The studies on tool wear show that flank wear increases with speed and feed. The end-mill tool wear is higher on machining the aluminum alloy-silicon carbide composites than on machining the plain aluminum alloy.

  20. Microstructure and Wear Behavior of High-Cr WCI Matrix Surface Composite Reinforced with Cemented Carbide Rods

    NASA Astrophysics Data System (ADS)

    Hou, Shuzeng; Bao, Chonggao; Zhang, Zhiyun; Bai, Yaping

    2013-07-01

    The present article reports a new superior wear resistance surface composite prepared by a vacuum evaporative pattern casting-in process. This surface composite was constructed with reinforcing cemented carbide rod (CCR) array within high-Cr white cast iron (WCI) matrix. Three reaction zones that formed around the CCRs were characterized and established the good metallurgical bonding between CCRs and matrix. In addition, some compound carbide containing Fe, Cr, W, and Co elements were formed in the reaction zones, owing to the partial dissolution of the CCRs and the resulting interdiffusion of elements such as W, Co, C, Fe, and Cr. The wear behavior of the composite was evaluated and compared with unreinforced high-Cr WCI by means of a three-body abrasive wear tester. The results showed that the wear resistance of the composite was significantly higher than that of the unreinforced high-Cr WCI. The exciting wear resistance can be ascribed to protective effect introduced by the CCRs during wear process and the good metallurgical bonding between CCRs and matrix.

  1. Aluminum-titanium hydride-boron carbide composite provides lightweight neutron shield material

    NASA Technical Reports Server (NTRS)

    Poindexter, A. M.

    1967-01-01

    Inexpensive lightweight neutron shield material has high strength and ductility and withstands high internal heat generation rates without excessive thermal stress. This composite material combines structural and thermal properties of aluminum, neutron moderating properties of titanium hydride, and neutron absorbing characteristics of boron carbide.

  2. Ceramic composites reinforced with modified silicon carbide whiskers and method for modifying the whiskers

    DOEpatents

    Tiegs, Terry N.; Lindemer, Terrence B.

    1991-01-01

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  3. Ceramic composites reinforced with modified silicon carbide whiskers and method for modifying the whiskers

    DOEpatents

    Tiegs, T.N.; Lindemer, T.B.

    1991-02-19

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  4. Joining and Assembly of Silicon Carbide-based Advanced Ceramics and Composites for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Singh, M.

    2004-01-01

    Silicon carbide based advanced ceramics and fiber reinforced composites are under active consideration for use in wide variety of high temperature applications within the aeronautics, space transportation, energy, and nuclear industries. The engineering designs of ceramic and composite component require fabrication and manufacturing of large and complex shaped parts of various thicknesses. In many instances, it is more economical to build up complex shapes by joining simple geometrical shapes. In addition these components have to be joined or assembled with metallic sub-components. Thus, joining and attachment have been recognized as enabling technologies for successful utilization of ceramic components in various demanding applications. In this presentation, various challenges and opportunities in design, fabrication, and testing o high temperature joints in ceramic matrix composites will be presented. Silicon carbide based advanced ceramics (CVD and hot pressed), and C/SiC and SiC/SiC composites, in different shapes and sizes, have been joined using an affordable, robust ceramic joining technology (ARCJoinT). Microstructure and high temperature mechanical properties of joints in silicon carbide ceramics and CVI and melt infiltrated SiC matrix composites will,be reported. Various joint design philosophies and design issues in joining of ceramics and composites well be discussed.

  5. High Temperature Joining and Characterization of Joint Properties in Silicon Carbide-Based Composite Materials

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.; Singh, Mrityunjay

    2015-01-01

    Advanced silicon carbide-based ceramics and composites are being developed for a wide variety of high temperature extreme environment applications. Robust high temperature joining and integration technologies are enabling for the fabrication and manufacturing of large and complex shaped components. The development of a new joining approach called SET (Single-step Elevated Temperature) joining will be described along with the overview of previously developed joining approaches including high temperature brazing, ARCJoinT (Affordable, Robust Ceramic Joining Technology), diffusion bonding, and REABOND (Refractory Eutectic Assisted Bonding). Unlike other approaches, SET joining does not have any lower temperature phases and will therefore have a use temperature above 1315C. Optimization of the composition for full conversion to silicon carbide will be discussed. The goal is to find a composition with no remaining carbon or free silicon. Green tape interlayers were developed for joining. Microstructural analysis and preliminary mechanical tests of the joints will be presented.

  6. Thermal expansion of laminated, woven, continuous ceramic fiber/chemical-vapor-infiltrated silicon carbide matrix composites

    NASA Technical Reports Server (NTRS)

    Eckel, Andrew J.; Bradt, Richard C.

    1990-01-01

    Thermal expansions of three two-dimensional laminate, continuous fiber/chemical-vapor-infiltrated silicon carbide matrix composites reinforced with either FP-Alumina (alumina), Nextel (mullite), or Nicalon (Si-C-O-N) fibers are reported. Experimental thermal expansion coefficients parallel to a primary fiber orientation were comparable to values calculated by the conventional rule-of-mixtures formula, except for the alumina fiber composite. Hysteresis effects were also observed during repeated thermal cycling of that composite. Those features were attributed to reoccurring fiber/matrix separation related to the micromechanical stresses generated during temperature changes and caused by the large thermal expansion mismatch between the alumina fibers and the silicon carbide matrix.

  7. Fracture toughness of hydroxyapatite/mica composite, packed hydroxyapatite, alumina ceramics, silicon nitride and -carbide.

    PubMed

    Nordström, E G; Yokobori, A T; Yokobori, T; Aizawa, Y

    1998-01-01

    By using the fracture toughness estimation method based on two-dimensional map, it was found that the ductility of the high porosity hydroxyapatite/mice composite was comparable with silicon carbide. It was measured to be higher than that of packed hydroxyapatite. Alumina ceramics with more than 96% aluminium oxide showed a higher fracture toughness than the composite material. When bending strength was compared, the strength of the composite was two or three times lower than that of packed hydroxyapatite and much lower than the other studied materials. The composite material showed high porosity, which in turn gives it a lower bending strength. However, the high porosity is more favourable for biocompatibility.

  8. Process of high temperature synthesis in producing composite carbide powders for thermally sprayed coatings

    NASA Astrophysics Data System (ADS)

    Szymański, K.; Formanek, B.

    2011-05-01

    The paper presents the characterization of powders containing hard phases of chromium carbides in a NiCr matrix, intended for thermal spraying coatings. The synthesized composite powder containing hard phases and plastic matrix, produced in high-temperature synthesis with chosen powder metallurgy processes has been presented. Commercial materials, such as NiCr- CrxCy, are fabricated by means of agglomeration and sintering method. Processes of high temperature synthesis of Cr3C2, Cr7C3, Cr23C6 carbides combined with NiCr powder mechanical alloying are presented in the article. Parameters of the carbides synthesis were determined in the reactive -protective atmosphere. In the rotation- vibration mill, processes were conducted using grinding and appropriate mechanical alloying at variable amplitude. The standard and synthesized powders were thermally sprayed by HVOF method in Jet Kote II and Diamond Jet system. The structure and phase composition of the powders and coatings were determined by: light and scanning microscopy, X-ray phase analysis (RTG) and energy dispersive X-ray analysis (EDX). The structure and wear properties of HVOF sprayed coatings containing chromium carbides has been presented. The thermally sprayed coatings are characterized of wear resistance in abrasion and erosion tests. The sprayed coatings characterized high resistance in wear conditions.

  9. Factors Controlling Elevated Temperature Strength Degradation of Silicon Carbide Composites

    NASA Technical Reports Server (NTRS)

    2005-01-01

    For 5 years, the cooperative agreement NCC3-763 has focused on the development and understanding of Sic-based composites. Most of the work was performed in the area of SiC fiber-reinforced composites for UEET and NGLT and in collaboration with Goodrich Corporation under a partially reimbursable Space Act Agreement. A smaller amount of work was performed on C fiber-reinforced SiC matrix composites for NGLT. Major accomplishments during this agreement included: Improvements to the interphase used in melt-infiltrated (MI) SiC/SiC composites which increases the life under stressed-oxidation at intermediate temperatures referred to as "outside-debonding". This concept is currently in the patent process and received a Space Act Award. Mechanistic-based models of intermediate temperature degradation for MI SiC/SiC Quantification and relatively robust relationships for matrix crack evolution under stress in SiC/SiC composites which serve as the basis for stress-strain and elevated temperature life models The furthering of acoustic emission as a useful tool in composite damage evolution and the extension of the technique to other composite systems Development of hybrid C-SiC fiber-reinforced SiC matrix composites Numerous presentations at conferences, industry partners, and government centers and publications in recognized proceedings and journals. Other recognition of the author's accomplishments by NASA with a TGIR award (2004), NASA's Medal for Public Service (2004), and The American Ceramic Society s Richard M. Fulrath Award (2005). The following will briefly describe the work of the past five years in the three areas of interest: SiC/SiC composite development, mechanistic understanding and modeling of SiC/SiC composites, and environmental durability of C/SiC composites. More detail can be found in the publications cited at the end of this report.

  10. Evolution of Morphology and Composition of the Carbides in Cr-Mo-V Steel after Service Exposure

    NASA Astrophysics Data System (ADS)

    Dong, Jiling; Shin, Keesam; He, Yinsheng; Song, Geewook; Jung, Jinesung

    2011-06-01

    Low alloy Cr-Mo-V steels are usually used in steam power generation units. The evolution of the carbides often leads to embrittlement of the components during elongated service. Therefore, the determination of carbide evolution mechanism during long-time service is important to understand and prevent premature failures such as temper embrittlement. In this study, low alloy Cr-Mo-V steels used as main steam pipes in a thermal power plant were studied after various service times as well as in the as-fabricated condition. Electron microscopic analyses were carried out on extraction replicas to observe and analyze the morphology and composition of the carbides. Predominant plate-like vanadium-rich carbides were observed in the as-fabricated condition. When exposed to on-site service, the V-rich carbides transformed to Mo-rich carbides which have a typical H morphology. The change of morphology and composition of the carbide is mainly due to the gradual depletion of Mo from the solid solution. In addition, a non-destructive carbide extraction method was established for examination of the precipitates in the working turbine rotor.

  11. New low-temperature processing for boron carbide/aluminum-based composite armor. Final report

    SciTech Connect

    Pyzik, A.J.; Williams, P.D.; McCombs, A.

    1990-06-01

    The developed Boron Carbide/Aluminum based materials are a promising alternative for the use in lightweight armor application. The advantage of B4C/A1 composite over the traditional metal armor is its ballistic limit of 80 to 90% of that for hot pressed B4C, thus similar to ceramics such as A1N or SiC. The advantage of B4C/A1 over monolithic ceramic armor is its higher toughness. The ballistic efficiency of B4C materials, relative to hot-pressed boron carbide, was found to be directly related to the initial boron carbide content, the B-C-A1 phases formed in situ, and their continuity. The highest improvement of ballistic efficiency was associated with increasing contents of B4C and A1B2 in the system. The Rapid Omnidirectional Compaction process is a suitable technique to produce nearly dense B4C/A1 cermet at the low temperature. Dense, but soft, cermets can be near-net shaped and then changed into hard, ceramic-like structure through heat-treatment. Mechanical properties of B4C/A1 cermet depend mostly on the concentration and continuity of the boron carbide phase. Colloidal processing and post densification heat-treatment can be used to further modify properties for the application at hand.

  12. Article and method for making complex shaped preform and silicon carbide composite by melt infiltration

    NASA Technical Reports Server (NTRS)

    Steibel, James D. (Inventor); Corman, Gregory S. (Inventor); Schikner, Robert C. (Inventor); Szweda, Andrew (Inventor)

    2000-01-01

    Small diameter silicon carbide-containing fibers are provided in a bundle such as a fiber tow that can be formed into a structure where the radii of curvature is not limited to 10-20 inches. An aspect of this invention is directed to impregnating the bundles of fibers with the slurry composition to substantially coat the outside surface of an individual fiber within the bundle and to form a complex shaped preform with a mass of continuous fibers.

  13. Article and method for making complex shaped preform and silicon carbide composite by melt infiltration

    NASA Technical Reports Server (NTRS)

    Steibel, James D. (Inventor); Corman, Gregory S. (Inventor); Schikner, Robert C. (Inventor); Szweda, Andrew (Inventor)

    2001-01-01

    Small diameter silicon carbide-containing fibers are provided in a bundle such as a fiber tow that can be formed into a structure where the radii of curvature is not limited to 10-20 inches. An aspect of this invention is directed to impregnating the bundles of fibers with the slurry composition to substantially coat the outside surface of an individual fiber within the bundle and to form a complex shaped preform with a mass of continuous fibers.

  14. Silicon carbide whisker reinforced composites and method for making same

    DOEpatents

    Wei, G.C.

    1984-02-09

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties, especially increased fracture toughness. In the formation of these ceramic composites, the single-crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al/sub 2/O/sub 3/, mullite, or B/sub 4/C. The mixtures which contain a homogeneous dispersion of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600 to 1950/sup 0/C with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m/sup 1/2/ which represents as much as a two-fold increase over that of the matrix material.

  15. Isotopic Composition of Barium in Single Presolar Silicon Carbide Grains

    NASA Technical Reports Server (NTRS)

    Savina, M. R.; Tripa, C. E.; Pellin, M. J.; Davis, A. M.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2002-01-01

    We have measured Ba isotope distributions in individual presolar SiC grains. We find that the Ba isotopic composition in mainstream SiC grains is consistent with models of nucleosynthesis in low to intermediate mass asymptotic giant branch (AGB) stars. Additional information is contained in the original extended abstract.

  16. Dry Sliding Wear behaviour of Aluminium-Red mud- Tungsten Carbide Hybrid metal matrix composites

    NASA Astrophysics Data System (ADS)

    Devi Chinta, Neelima; Selvaraj, N.; Mahesh, V.

    2016-09-01

    Red mud is an industrial waste obtained during the processing of alumina by Bayer's process. An attempt has been made to utilize the solid waste by using it as the reinforcement material in metal matrix composites. Red mud received from NALCO has been subjected for sieve analysis and milled to 42 nanometers using high energy ball mill. Red mud is used as a reinforcement material in Pure Aluminium matrix composite at 2%, 4%, and 6% weight at 100 microns level as well as 42 nano meters along with 4%Tungsten carbide by weight. Micro and Nano structured red mud powders, Tungsten carbide powder and Aluminium is mixed in a V-Blender, compacted at a pressure of 40 bar and samples are prepared by conventional sintering with vacuum as medium. In this current work, dry sliding wear characteristics at normal and heat treatment conditions are investigated with optimal combination of Aluminium, Tungsten carbide and different weight fractions of micro and nano structured red mud powder.

  17. Modification of silicon carbide fibers for use in SiC/Ti composites

    NASA Technical Reports Server (NTRS)

    Landis, H. S.; Unman, J.; Brewer, W. D.; Naidu, S. V. N.

    1981-01-01

    The degradation of silicon carbide fibers during exposure to conditions typical of composite fabrication was investigated. The tensile strength of pristine fibers and fibers sputtered with thin metal coatings were determined before and after treatment at 870 C for one hour in vacuum. Each fiber strength distribution was related by an analytical procedure to a projected composite ultimate tensile strength (PC UTS). The results indicate that a thin aluminum diffusion barrier can yield a 150 percent increase in PC UTS over the baseline SiC/Ti system.

  18. Carbide/Fluoride/Silver Self-Lubricating Composite

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.

    1987-01-01

    Bearing coatings survive at operating temperatures up to 870 degrees C. PS200 composite self-lubricating coating for bearing applications operating at temperatures above failure points of traditional solid lubricants. Excellent friction and wear performance in oxidizing atmospheres up to 1,600 degrees F and reducing atmospheres up to 1,400 degrees F. Performance needed for development of advanced heat engines as adiabatic diesel and Stirling engine.

  19. Formation mechanism of a silicon carbide coating for a reinforced carbon-carbon composite

    NASA Technical Reports Server (NTRS)

    Rogers, D. C.; Shuford, D. M.; Mueller, J. I.

    1975-01-01

    Results are presented for a study to determine the mechanisms involved in a high-temperature pack cementation process which provides a silicon carbide coating on a carbon-carbon composite. The process and materials used are physically and chemically analyzed. Possible reactions are evaluated using the results of these analytical data. The coating is believed to develop in two stages. The first is a liquid controlled phase process in which silicon carbide is formed due to reactions between molten silicon metal and the carbon. The second stage is a vapor transport controlled reaction in which silicon vapors react with the carbon. There is very little volume change associated with the coating process. The original thickness changes by less than 0.7%. This indicates that the coating process is one of reactive penetration. The coating thickness can be increased or decreased by varying the furnace cycle process time and/or temperature to provide a wide range of coating thicknesses.

  20. Gravitational effects on body composition in birds

    NASA Technical Reports Server (NTRS)

    Smith, A. H.; Sanchez P., O.; Burton, R. R.

    1975-01-01

    Gallinaceous birds, presenting a wide range of body size, were adapted physiologically to hyperdynamic environments, provided by chronic centrifugation. Chemical composition was measured directly on prepared carcasses, which were anatomically comparable, and more amenable to analysis than the intact body. Body mass and body fat decreased arithmetically with increasing field strength and also with increasing body mass. Water content of lean tissue increased in hyperdynamic environments, but irrespectively of body size.

  1. Tensile creep of silicon carbide whisker-reinforced alumina composites

    NASA Astrophysics Data System (ADS)

    Quan, Guang-Chun

    Alumina composites with 10, 20 and 30 volume % SiC whiskers were fabricated using colloidal processing methods followed by uniaxial hot pressing. The tensile creep properties of these materials have been studied between 1200°C and 1400°C. The composite slurries showed the best stability at pH = 2, which led to uniform distribution of whiskers in the final products. However, at pH ≥ 6 flocculation occurred between whiskers, resulting in whisker agglomerates in the matrix. Distribution of whiskers was characterised using neutron diffraction methods, which indicated that the whisker orientation could not be altered significantly by adjusting pH. All the composites showed much superior tensile creep resistance compared to pure alumina and the effect of increasing whisker volume fraction was significant up to 30%. Relatively high stress exponents were found, which is most probably associated with much enhanced cavitational creep in tension. The activation energy varied with whisker volume fraction, temperature and applied stress in a complex manner. This combined with the temperature-dependent stress exponents makes the identification of creep mechanisms difficult. Nevertheless, it appears that at moderate stress level grain boundary diffusion and grain boundary sliding (GBS) become more significant as whisker volume fraction increases. The composites containing 20 and 30% whiskers showed significant anelastic strain recovery (˜0.001) following tensile creep, which is consistent with earlier reports that involved bending creep tests. The whisker bending effect was studied by measuring the peak width of (111) SiC planes (perpendicular to the whisker axis) at various conditions. The difference in the peak width at room temperature was found to be insignificant before and after creep. Moreover, during in-situ neutron diffraction measurement at 1400°C, no measurable variation in the peak width was recorded from the crept samples that were cooled under load. It may be

  2. Lightweight graphene nanoplatelet/boron carbide composite with high EMI shielding effectiveness

    NASA Astrophysics Data System (ADS)

    Tan, Yongqiang; Luo, Heng; Zhang, Haibin; Zhou, Xiaosong; Peng, Shuming

    2016-03-01

    Lightweight graphene nanoplatelet (GNP)/boron carbide (B4C) composites were prepared and the effect of GNPs loading on the electromagnetic interference (EMI) shielding effectiveness (SE) has been evaluated in the X-band frequency range. Results have shown that the EMI SE of GNP/B4C composite increases with increasing the GNPs loading. An EMI SE as high as 37 ˜ 39 dB has been achieved in composite with 5 vol% GNPs. The high EMI SE is mainly attributed to the high electrical conductivity, high dielectric loss as well as multiple reflections by aligned GNPs inside the composite. The GNP/B4C composite is demonstrated to be promising candidate of high-temperature microwave EMI shielding material.

  3. One step deposition of highly adhesive diamond films on cemented carbide substrates via diamond/β-SiC composite interlayers

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Zhuang, Hao; Jiang, Xin

    2015-12-01

    Deposition of adherent diamond films on cobalt-cemented tungsten carbide substrates has been realized by application of diamond/beta-silicon carbide composite interlayers. Diamond top layers and the interlayers were deposited in one single process by hot filament chemical vapor deposition technique. Two different kinds of interlayers have been employed, namely, gradient interlayer and interlayer with constant composition. The distribution of diamond and beta-silicon carbide phases was precisely controlled by manipulating the gas phase composition. X-ray diffraction and Raman spectroscopy were employed to determine the existence of diamond, beta-silicon carbide and cobalt silicides (Co2Si, CoSi) phases, as well as the quality of diamond crystal and the residual stress in the films. Rockwell-C indentation tests were carried out to evaluate the film adhesion. It is revealed that the adhesion of the diamond film is drastically improved by employing the interlayer. This is mainly influenced by the residual stress in the diamond top layer, which is induced by the different thermal expansion coefficient of the film and the substrate. It is even possible to further suppress the stress by manipulating the distribution of diamond and beta-silicon carbide in the interlayer. The most adhesive diamond film on cemented carbide is thus obtained by employing a gradient composite interlayer.

  4. Effective load transfer by a chromium carbide nanostructure in a multi-walled carbon nanotube/copper matrix composite

    NASA Astrophysics Data System (ADS)

    Cho, Seungchan; Kikuchi, Keiko; Kawasaki, Akira; Kwon, Hansang; Kim, Yangdo

    2012-08-01

    Multi-walled carbon nanotube (MWCNT) reinforced copper (Cu) matrix composites, which exhibit chromium (Cr) carbide nanostructures at the MWCNT/Cu interface, were prepared through a carbide formation using CuCr alloy powder. The fully densified and oriented MWCNTs dispersed throughout the composites were prepared using spark plasma sintering (SPS) followed by hot extrusion. The tensile strengths of the MWCNT/CuCr composites increased with increasing MWCNTs content, while the tensile strength of MWCNT/Cu composite decreased from that of monolithic Cu. The enhanced tensile strength of the MWCNT/CuCr composites is a result of possible load-transfer mechanisms of the interfacial Cr carbide nanostructures. The multi-wall failure of MWCNTs observed in the fracture surface of the MWCNT/CuCr composites indicates an improvement in the load-bearing capacity of the MWCNTs. This result shows that the Cr carbide nanostructures effectively transferred the tensile load to the MWCNTs during fracture through carbide nanostructure formation in the MWCNT/Cu composite.

  5. Effective load transfer by a chromium carbide nanostructure in a multi-walled carbon nanotube/copper matrix composite.

    PubMed

    Cho, Seungchan; Kikuchi, Keiko; Kawasaki, Akira; Kwon, Hansang; Kim, Yangdo

    2012-08-10

    Multi-walled carbon nanotube (MWCNT) reinforced copper (Cu) matrix composites, which exhibit chromium (Cr) carbide nanostructures at the MWCNT/Cu interface, were prepared through a carbide formation using CuCr alloy powder. The fully densified and oriented MWCNTs dispersed throughout the composites were prepared using spark plasma sintering (SPS) followed by hot extrusion. The tensile strengths of the MWCNT/CuCr composites increased with increasing MWCNTs content, while the tensile strength of MWCNT/Cu composite decreased from that of monolithic Cu. The enhanced tensile strength of the MWCNT/CuCr composites is a result of possible load-transfer mechanisms of the interfacial Cr carbide nanostructures. The multi-wall failure of MWCNTs observed in the fracture surface of the MWCNT/CuCr composites indicates an improvement in the load-bearing capacity of the MWCNTs. This result shows that the Cr carbide nanostructures effectively transferred the tensile load to the MWCNTs during fracture through carbide nanostructure formation in the MWCNT/Cu composite. PMID:22797555

  6. Carbide Coatings for Nickel Alloys, Graphite and Carbon/Carbon Composites to be used in Fluoride Salt Valves

    SciTech Connect

    Nagle, Denis; Zhang, Dajie

    2015-10-22

    The focus of this research was concerned with developing materials technology that supports the evolution of Generation IV Advanced High Temperature Reactor (AHTR) concepts. Specifically, we investigate refractory carbide coatings for 1) nickel alloys, and 2) commercial carbon-carbon composites (CCCs). Numerous compelling reasons have driven us to focus on carbon and carbide materials. First, unlike metals, the strength and modulus of CCCs increase with rising temperature. Secondly, graphite and carbon composites have been proven effective for resisting highly corrosive fluoride melts such as molten cryolite [Na₃AlF₆] at ~1000°C in aluminum reduction cells. Thirdly, graphite and carbide materials exhibit extraordinary radiation damage tolerance and stability up to 2000°C. Finally, carbides are thermodynamically more stable in liquid fluoride salt than the corresponding metals (i.e. Cr and Zr) found in nickel based alloys.

  7. Silicon carbide composite for light water reactor fuel assembly applications

    NASA Astrophysics Data System (ADS)

    Yueh, Ken; Terrani, Kurt A.

    2014-05-01

    The feasibility of using SiCf-SiCm composites in light water reactor (LWR) fuel designs was evaluated. The evaluation was motivated by the desire to improve fuel performance under normal and accident conditions. The Fukushima accident once again highlighted the need for improved fuel materials that can maintain fuel integrity to higher temperatures for longer periods of time. The review identified many benefits as well as issues in using the material. Issues perceived as presenting the biggest challenges to the concept were identified to be flux gradient induced differential volumetric swelling, fragmentation and thermal shock resistance. The oxidation of silicon and its release into the coolant as silica has been identified as an issue because existing plant systems have limited ability for its removal. Detailed evaluation using available literature data and testing as part of this evaluation effort have eliminated most of the major concerns. The evaluation identified Boiling Water Reactor (BWR) channel, BWR fuel water tube, and Pressurized Water Reactor (PWR) guide tube as feasible applications for SiC composite. A program has been initiated to resolve some of the remaining issues and to generate physical property data to support the design of commercial fuel components.

  8. Nutritional assessment with body composition measurements

    SciTech Connect

    Shizgal, H.M.

    1987-09-01

    The measurement of body composition by multiple isotope dilution provides an accurate and precise measure of both the nutritional state and the response to nutritional support. A multiple isotope dilution technique has been developed that permits measurement of the three major components of body composition: body fat, extracellular mass (ECM), and body cell mass (BCM). Normal body composition was defined by data obtained in 25 healthy volunteers. Malnutrition is characterized by a loss of BCM and an expansion of the ECM, and as a result the lean body mass is not significantly different from normal. The loss of body weight with malnutrition therefore often reflects the loss of body fat. The utility of body composition measurements was demonstrated by determining the effect of total parenteral nutrition on body composition to determine the relationship between caloric intake and the change in the BCM. A statistically significant relationship was developed which demonstrated that a caloric intake in the range of 30-40 cal/kg/day is required for maintenance. To restore a depleted or malnourished BCM requires a caloric intake in excess of that required for maintenance. The measurement of body composition by multiple isotope dilution is complex and time consuming, and requires specialized laboratory facilities and specially trained personnel. As a result, these measurements are not suited for routine patient management, but should rather be reserved for research purposes.

  9. Evaluation of Body Composition: Why and How?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluation of human body composition in vivo remains a critical component in the assessment of nutritional status of an individual.Whereas traditional measurements of standing height and body weight provide information on body mass index and, hence, the risk of some chronic diseases, advanced techno...

  10. Phase evolution in carbide dispersion strengthened nanostructured copper composite by high energy ball milling

    NASA Astrophysics Data System (ADS)

    Hussain, Zuhailawati; Nur Hawadah, M. S.

    2012-09-01

    In this study, high-energy ball milling was applied to synthesis in situ nanostructured copper based composite reinforced with metal carbides. Cu, M (M=W or Ti) and graphite powder mixture were mechanically alloyed for various milling time in a planetary ball mill with composition of Cu-20vol%WC and Cu-20vol%TiC. Then the as-milled powder were compacted at 200 to 400 MPa and sintered in a vacuum furnace at 900°C. The results of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis showed that formation of tungsten carbides (W2C and WC phases) was observed after sintering of Cu-W-C mixture while TiC precipitated in as-milled powder of Cu-Ti-C composite after 5 h and become amorphous with longer milling. Mechanism of MA explained the cold welding and fracturing event during milling. Cu-W-C system shows fracturing event is more dominant at early stage of milling and W particle still existed after milling up to 60 h. While in Cu-Ti-C system, cold welding is more dominant and all Ti particles dissolved into Cu matrix.

  11. A Model for the Oxidation of Carbon Silicon Carbide Composite Structures

    NASA Technical Reports Server (NTRS)

    Sullivan, Roy M.

    2004-01-01

    A mathematical theory and an accompanying numerical scheme have been developed for predicting the oxidation behavior of carbon silicon carbide (C/SiC) composite structures. The theory is derived from the mechanics of the flow of ideal gases through a porous solid. The result of the theoretical formulation is a set of two coupled nonlinear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The nonlinear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual method, allowing for the solution of the differential equations numerically. The numerical method is demonstrated by utilizing the method to model the carbon oxidation and weight loss behavior of C/SiC specimens during thermogravimetric experiments. The numerical method is used to study the physics of carbon oxidation in carbon silicon carbide composites.

  12. Development of high temperature materials for solid propellant rocket nozzle applications. [tantalum carbides-tungsten fiber composites

    NASA Technical Reports Server (NTRS)

    Manning, C. R., Jr.; Honeycutt, L., III

    1974-01-01

    Evaluation of tantalum carbide-tungsten fiber composites has been completed as far as weight percent carbon additions and weight percent additions of tungsten fiber. Extensive studies were undertaken concerning Young's Modulus and fracture strength of this material. Also, in-depth analysis of the embrittling effects of the extra carbon additions on the tungsten fibers has been completed. The complete fabrication procedure for the tantalum carbide-tungsten fiber composites with extra carbon additions is given. Microprobe and metallographic studies showed the effect of extra carbon on the tungsten fibers, and evaluation of the thermal shock parameter fracture strength/Young's Modulus is included.

  13. The effects of erodent particle size and composition on the erosion of chromium carbide based coatings

    SciTech Connect

    Walsh, P.N.; Quets, J.M.; Tucker, R.C. Jr.

    1994-12-31

    A number of studies and field experience have demonstrated the efficacy of use of chromium carbide based coatings on steam turbine components to reduce the effects of solid particle erosion. To optimize the performance of these coatings, a cost effective laboratory test is needed to facilitate the choice of coating composition, morphology, and deposition method. A variety of test types and test parameters have been reported with varying relative rankings of the various coatings evaluated. A critical review of past work has been made, with new data added for clarification. The particle size of the erodent used as well as its composition has been shown to be of particular importance. A correlation between field experience and selected laboratory test parameters then facilitates the optimum choice of coatings.

  14. Microstructure and thermal properties of copper–diamond composites with tungsten carbide coating on diamond particles

    SciTech Connect

    Kang, Qiping; He, Xinbo Ren, Shubin; Liu, Tingting; Liu, Qian; Wu, Mao; Qu, Xuanhui

    2015-07-15

    An effective method for preparing tungsten carbide coating on diamond surfaces was proposed to improve the interface bonding between diamond and copper. The WC coating was formed on the diamond surfaces with a reaction medium of WO{sub 3} in mixed molten NaCl–KCl salts and the copper–diamond composites were obtained by vacuum pressure infiltration of WC-coated diamond particles with pure copper. The microstructure of interface bonding between diamond and copper was discussed. Thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites were investigated. Results indicated that the thermal conductivity of as-fabricated composite reached 658 W m{sup −} {sup 1} K{sup −} {sup 1}. Significant reduction in coefficient of thermal expansion of the composite compared with that of pure copper was obtained. - Highlights: • WC coating was successfully synthesized on diamond particles in molten salts. • WC coating obviously promoted the wettability of diamond and copper matrix. • WC coating greatly enhanced the thermal conductivity of Cu–diamond composite. • The composites are suitable candidates for heat sink applications.

  15. Measurement of Body Composition in Children.

    ERIC Educational Resources Information Center

    Lohman, T. G.

    1982-01-01

    Identification and treatment of obesity in children is believed to be an important factor in its control during the adult years. Laboratory and field methods for body composition measurement are described along with estimates of body fat content from anthropometric dimensions. (CJ)

  16. Assessing body composition in infants and toddlers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to compare different body composition techniques in infants and toddlers. Anthropometric measures including mid-upper arm circumference (MAC), triceps skinfold thickness (TSF), and weight-for-height or -length Z-scores (WHZ), and measures of body fat mass assessed wit...

  17. Body composition in Egyptian Turner syndrome girls

    PubMed Central

    Zaki, Moushira Erfan; Afifi, Hanan H.

    2013-01-01

    OBJECTIVE: This cross-sectional study was undertaken to construct the new body fat % curve and provide body composition reference data for adolescent girls with Turner syndrome (TS). They diagnosed cytogenetically by blood karyotyping and not treated with growth hormone (GH). MATERIALS AND METHODS: The study included 70 TS girls from age 13 years to age 17 years. Body composition was measured by bioelectrical impedance. Smoothed centile charts were derived by using the least mean square (LMS) method. RESULTS: The new body fat curves reflect the increase of body fat mass (FM) from age 13 years to age 17 years. Body FM % of Egyptian TS girls was lower when compared with age-matched American untreated TS girls. CONCLUSION: This study presents the new body fat curves and reference values of body composition for untreated Egyptian TS adolescent girls. The present charts can be used for direct assessment of body FM % for Egyptian TS girls and evaluation for cases on GH treatment or other growth promoting therapy. PMID:24019614

  18. Microwave sintering of boron carbide

    DOEpatents

    Blake, R.D.; Katz, J.D.; Petrovic, J.J.; Sheinberg, H.

    1988-06-10

    A method for forming boron carbide into a particular shape and densifying the green boron carbide shape. Boron carbide in powder form is pressed into a green shape and then sintered, using a microwave oven, to obtain a dense boron carbide body. Densities of greater than 95% of theoretical density have been obtained. 1 tab.

  19. Analysis of alumina-based titanium carbide composites by laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Ahmad, Kaleem; Tawfik, Walid; Farooq, Wazirzada A.; Singh, Jagdish P.

    2014-06-01

    In this work, alumina (Al2O3) containing different volume % of titanium carbide (TiC) ranging from 0 to 30 were consolidated by the novel spark plasma sintering. The spectroscopic analysis of the plasma generated by irradiation of laser Nd:YAG (λ = 1,064 nm) on different concentrations of the composites in air atmospheric pressure was performed. The qualitative examination of the composites confirms the presence of aluminum, titanium, and carbon as major elements, while magnesium and sodium have been found as minor trace elements. Plasma parameters were estimated by assuming the LTE conditions for optically thin plasma. The electron density and temperature were evaluated by using the Stark broadening and intensity of selected aluminum emission lines, respectively. The addition of TiC to Al2O3 shows a linear behavior with plasma temperature corroborated by the calibration curve of Ti in the composites. The results suggest that calibration curve between plasma temperature and the composites can be used to estimate different concentrations of TiC in Al2O3 without analyzing the whole elements in the composites and thus opens up new applications of LIBS in ceramic industry.

  20. Effect of carbide particles on the ablation properties of tungsten composites

    SciTech Connect

    Song Guiming; Zhou Yu; Wang Yujin

    2003-06-15

    The high temperature ablation behavior of tungsten composites containing carbides produced by vacuum hot pressing is studied as a function of reinforcement chemistry (ZrC and TiC) and content using a self-made oxyacetylene ablation equipment. A dynamic responding multiwavelength pyrometer was employed to measure the temperature of the ablation surface, and a thermocouple was employed to measure the temperature of the back surface during the time that a specimen was being ablated. The mass and linear ablation rates are lower in composites containing ZrC, decreasing with increasing particle content in both composites system. The values of the mass and linear ablation rates were in the order from high to low: W>30TiC/W>40TiC/W>30ZrC/W>40ZrC/W (30TiC/W stands for 30 vol.% TiC particle content in the W matrix, the same below). The important temperature curves of the ablation surfaces of specimens were successfully detected online. Ablated surfaces and vertical sections of the specimens were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Thermochemical oxidation of tungsten, TiC, and ZrC was the main ablation mechanism of ZrC/W and TiC/W composites. These ablation behaviors are discussed based on the thermophysical and chemical properties of both the composite systems.

  1. [Body composition and comorbidity in the elderly].

    PubMed

    Bonnefoy, Marc; Gilbert, Thomas

    2015-03-01

    Obesity and excess in fat versus lean mass is well known to enhance the risk of mortality and morbidity. Several recent works have pointed the importance of analysing more precisely body composition for the assessment of prognosis of patients in terms of cardiovascular outcomes and mortality. The body mass index (BMI), commonly used for defining obese patients, does not give sufficient indication on the body composition and distribution of fat mass. In the elderly population, relative excess in fat mass associated with a decrease in lean mass is frequently observed. In such situations of sarcopenic obesity, the relative weight stability can be misleading. Sarcopenic obesity is an emerging public health problem in the geriatric population. It appears to be the situation with the worst prognosis for cardiovascular risk. In addition, recent works have highlighted the major impact of visceral fat, clearly linked with cardiovascular events. Body composition has also an impact on other pathologic conditions such as dementia, sleep apnoea or cancer. The links between body composition and morbidity in the elderly population are presented in this review, with emphasis on adipokines and their interactions with other organs such as the heart, liver, skeletal muscle or bones. More precise measurements of body composition, rather than BMI alone, should be developed in the elderly population. PMID:26345585

  2. Body Composition Changes Associated With Methadone Treatment

    PubMed Central

    Sadek, Gamal E.; Chiu, Simon; Cernovsky, Zack Z.

    2016-01-01

    Background: Methadone is associated with a statistically significant increase in BMI in the first 2 years of treatment. Objectives: To evaluate the changes of body composition (bone mass, % fat, % muscle mass, % water, and basal metabolic rate) related to this increase. Patients and Methods: Changes in body composition were monitored, via bioelectrical impedance, in 29 patients in methadone treatment for opiate dependency (age 18 to 44, mean = 29.3, SD = 7.0, 13 men, 16 women). Results: Within one year from admission to treatment, a statistically significant (t-tests, P < 0.05) increase was noted in their body mass index (BMI), % of body fat, average body mass, and average basal metabolic rate, and relative decrease in their % of muscle mass and % of bone mass. Neither absolute bone mass nor muscle mass changed significantly. Conclusions: Physicians involved in care of methadone patients should recommend dietary and lifestyle changes to improve their overall health. PMID:27162765

  3. Skeletal and body composition evaluation

    NASA Technical Reports Server (NTRS)

    Mazess, R. B.

    1983-01-01

    Research on radiation detectors for absorptiometry; analysis of errors affective single photon absorptiometry and development of instrumentation; analysis of errors affecting dual photon absorptiometry and development of instrumentation; comparison of skeletal measurements with other techniques; cooperation with NASA projects for skeletal evaluation in spaceflight (Experiment MO-78) and in laboratory studies with immobilized animals; studies of postmenopausal osteoporosis; organization of scientific meetings and workshops on absorptiometric measurement; and development of instrumentation for measurement of fluid shifts in the human body were performed. Instrumentation was developed that allows accurate and precise (2% error) measurements of mineral content in compact and trabecular bone and of the total skeleton. Instrumentation was also developed to measure fluid shifts in the extremities. Radiation exposure with those procedures is low (2-10 MREM). One hundred seventy three technical reports and one hundred and four published papers of studies from the University of Wisconsin Bone Mineral Lab are listed.

  4. Elastic Moduli and Damping of Vibrational Modes of Aluminum/Silicon Carbide Composite Beams

    NASA Technical Reports Server (NTRS)

    Leidecker, Henning

    1996-01-01

    Elastic and shear moduli were determined for two aluminum matrix composites containing 20 and 40 volume percent discontinuous silicon carbide, respectively, using transverse, longitudinal, and torsional vibrational modes of specimens prepared as thin beams. These moduli are consistent with those determined from stress-strain measurements. The damping factors for these modes were also determined. Thermal properties are used to show that part of the damping of transverse modes is caused by the transverse thermal currents discussed by C. Zener (thermo-elastic damping); this damping is frequency-dependent with a maximum damping factor of approximately 0.002. The remaining damping is frequency-independent, and has roughly similar values in transverse, longitudinal, and torsional modes: approximately 0.0001.

  5. Thermal Properties of epoxy composites with silicon carbide and/or graphite

    NASA Astrophysics Data System (ADS)

    Kim, Jungsoo; Kim, Yang Do; Nam, Dae Geun; Bae, Jong-Seong; Yeum, Jeong Hyun; Oh, Weontae

    2016-02-01

    Epoxy composites were fabricated with a filler of silicon carbide (SiC) and/or graphite to improve the thermal conductivity and thereby enhance the transfer of the heat from the light-emitting diode (LED) to the heat sink. The two fillers (SiC and graphite) were each added either separately, within a content range of 10 - 50 wt.%, or together to give a combined total content of 40 - 60 wt.%. The effect of the filler addition on the thermal and the mechanical properties of the epoxy composites was examined. The filler-induced change on the structural properties was investigated by using a morphological analysis of the epoxy composites, and the thermal conductivity was analyzed by measuring the thermal diffusivity, heat specific, and density. To confirm the adhesive property with aluminum, which is mostly used as the heat sink material were tested, the mechanical properties by using a bonding test with a modified tensile test. The thermal and the mechanical properties were improved with increasing filler content in the epoxy composites. In the case of combined filler addition, graphite was more effective than SiC in increasing the thermal properties. However, excessive filler addition reduced the epoxy's natural adhesive property and hence degraded the mechanical properties.

  6. Recent advances and issues in development of silicon carbide composites for fusion applications

    NASA Astrophysics Data System (ADS)

    Nozawa, T.; Hinoki, T.; Hasegawa, A.; Kohyama, A.; Katoh, Y.; Snead, L. L.; Henager, C. H., Jr.; Hegeman, J. B. J.

    2009-04-01

    Radiation-resistant advanced silicon carbide (SiC/SiC) composites have been developed as a promising candidate of the high-temperature operating advanced fusion reactor. With the completion of the 'proof-of-principle' phase in development of 'nuclear-grade' SiC/SiC composites, the R&D on SiC/SiC composites is shifting toward the more pragmatic phase, i.e., industrialization of component manufactures and data-basing. In this paper, recent advances and issues in (1) development of component fabrication technology including joining and functional coating, e.g., a tungsten overcoat as a plasma facing barrier, (2) recent updates in characterization of non-irradiated properties, e.g., strength anisotropy and chemical compatibility with solid lithium-based ceramics and lead-lithium liquid metal breeders, and (3) irradiation effects are specifically reviewed. Importantly high-temperature neutron irradiation effects on microstructural evolution, thermal and electrical conductivities and mechanical properties including the fiber/matrix interfacial strength are specified under various irradiation conditions, indicating seemingly very minor influence on the composite performance in the design temperature range.

  7. Recent advances and issues in development of silicon carbide composites for fusion applications

    SciTech Connect

    Nozawa, Takashi; Hinoki, Tatsuya; Hasegawa, Akira; Kohyama, Akira; Katoh, Yutai; Snead, Lance Lewis; HenagerJr., Charles H.; Hegeman, Hans

    2009-01-01

    Radiation-resistant advanced silicon carbide (SiC/SiC) composites have been developed as a promising candidate of the high-temperature operating advanced fusion reactor. With the completion of the 'proof-of-principle' phase in development of 'nuclear-grade' SiC/SiC composites, the R&D on SiC/SiC composites is shifting toward the more pragmatic phase, i.e., industrialization of component manufactures and data-basing. In this paper, recent advances and issues in (1) development of component fabrication technology including joining and functional coating, e.g., a tungsten overcoat as a plasma facing barrier, (2) recent updates in characterization of non-irradiated properties, e.g., strength anisotropy and chemical compatibility with solid lithium-based ceramics and lead-lithium liquid metal breeders, and (3) irradiation effects are specifically reviewed. Importantly high-temperature neutron irradiation effects on microstructural evolution, thermal and electrical conductivities and mechanical properties including the fiber/matrix interfacial strength are specified under various irradiation conditions, indicating seemingly very minor influence on the composite performance in the design temperature range.

  8. Characterization of boron carbide particulate reinforced in situ copper surface composites synthesized using friction stir processing

    SciTech Connect

    Sathiskumar, R.; Murugan, N.; Dinaharan, I.; Vijay, S.J.

    2013-10-15

    Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B{sub 4}C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6 mm thick copper plates and packed with B{sub 4}C particles. The dimensions of the groove was varied to result in five different volume fractions of B{sub 4}C particles (0, 6, 12, 18 and 24 vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. Metallurgical characterization of the Cu/B{sub 4}C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B{sub 4}C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B{sub 4}C surface composites. When the volume fraction of B{sub 4}C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer. Highlights: • Fabrication of Cu/B{sub 4}C surface composite by friction stir processing • Analyzing the effect of B{sub 4}C particles on the properties of Cu/B4C surface composite • Increased volume fraction of B{sub 4}C particles reduced the area of surface composite. • Increased volume fraction of B{sub 4}C particles enhanced the microhardness and wear rate. • B{sub 4}C particles altered the wear mode from microcutting to abrasive.

  9. Scatter in Carbon/Silicon Carbide (C/SiC) Composites Quantified

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Gyekenyesi, John P.; Mital, Subodh K.

    2004-01-01

    Carbon-fiber-reinforced silicon carbide matrix (C/SiC) composites processed by chemical vapor infiltration are candidate materials for aerospace thermal structures. Carbon fibers can retain properties at very high temperatures, but they are known to have poor oxidation resistance in adverse, high-temperature environments. Nevertheless, the combination of CVI-SiC matrix with higher stiffness and oxidation resistance, the interfacial coating, and additional surface-seal coating provides the necessary protection to the carbon fibers, and makes the material viable for high-temperature space applications operating under harsh environments. Furthermore, C/SiC composites, like other ceramic matrix composites (CMCs), exhibit graceful non-catastrophic failure because of various inherent energy dissipating mechanisms. The material exhibits nonlinearity in deformation even at very low stress levels. This is the result of the severe matrix microcracking present in the as processed composite because of large differences between the coefficients of thermal expansion of the fiber and the matrix. Utilization of these advanced composites in next generation space vehicles will require innovative structural configurations, updated materials, and refined analyses. Structural safety issues for these vehicles are in direct competition with performance and cost. One would have to quantify the uncertainties associated with the design using formal probabilistic methods. Specifically four fundamental aspects on which analyses are based-- (1) loading conditions, (2) material behavior, (3) geometrical configurations, and (4) structural connections between the composite components and baseline structure--are stochastic in nature. A direct way to formally account for uncertainties is to develop probabilistic structural analysis methods where all participating variables are described by appropriate probability density functions. The present work, however, focuses on analyzing the stochastic

  10. Solid Oxide Membrane (SOM) Process for Facile Electrosynthesis of Metal Carbides and Composites

    NASA Astrophysics Data System (ADS)

    Zou, Xingli; Chen, Chaoyi; Lu, Xionggang; Li, Shangshu; Xu, Qian; Zhou, Zhongfu; Ding, Weizhong

    2016-09-01

    Metal carbides (MCs) and composites including TiC, SiC, TaC, ZrC, NbC, Ti5Si3/TiC, and Nb/Nb5Si3 have been directly electrosynthesized from their stoichiometric metal oxides/carbon (MOs/C) mixture precursors by an innovative solid oxide membrane (SOM)-assisted electrochemical process. MOs/C mixture powders including TiO2/C, SiO2/C, Ta2O5/C, ZrO2/C, Nb2O5/C, TiO2/SiO2/C, Nb2O5/SiO2 were pressed to form porous pellets and then served as cathode precursors. A SOM-based anode, made from yttria-stabilized zirconia (YSZ)-based membrane, was used to control the electroreduction process. The SOM electrochemical process was performed at 1273 K (1000 °C) and 3.5 to 4.0 V in molten CaCl2. The oxygen component contained in the MOs/C precursors was gradually removed during electroreduction process, and thus, MOs/C can be directly converted into MCs and composites at the cathode. The reaction mechanism of the electroreduction process and the characteristics of the obtained MCs and composites products were systematically investigated. The results show that the electrosynthesis process typically involves compounding, electroreduction, dissolution-electrodeposition, and in situ carbonization processes. The products can be predesigned and controlled to form micro/nanostructured MCs and composites. Multicomponent multilayer composites (MMCs) have also been tried to electrosynthesize in this work. It is suggested that the SOM-assisted electroreduction process has great potential to be used for the facile and green synthesis of various MCs and composites.

  11. Accurate body composition measures from whole-body silhouettes

    PubMed Central

    Xie, Bowen; Avila, Jesus I.; Ng, Bennett K.; Fan, Bo; Loo, Victoria; Gilsanz, Vicente; Hangartner, Thomas; Kalkwarf, Heidi J.; Lappe, Joan; Oberfield, Sharon; Winer, Karen; Zemel, Babette; Shepherd, John A.

    2015-01-01

    Purpose: Obesity and its consequences, such as diabetes, are global health issues that burden about 171 × 106 adult individuals worldwide. Fat mass index (FMI, kg/m2), fat-free mass index (FFMI, kg/m2), and percent fat mass may be useful to evaluate under- and overnutrition and muscle development in a clinical or research environment. This proof-of-concept study tested whether frontal whole-body silhouettes could be used to accurately measure body composition parameters using active shape modeling (ASM) techniques. Methods: Binary shape images (silhouettes) were generated from the skin outline of dual-energy x-ray absorptiometry (DXA) whole-body scans of 200 healthy children of ages from 6 to 16 yr. The silhouette shape variation from the average was described using an ASM, which computed principal components for unique modes of shape. Predictive models were derived from the modes for FMI, FFMI, and percent fat using stepwise linear regression. The models were compared to simple models using demographics alone [age, sex, height, weight, and body mass index z-scores (BMIZ)]. Results: The authors found that 95% of the shape variation of the sampled population could be explained using 26 modes. In most cases, the body composition variables could be predicted similarly between demographics-only and shape-only models. However, the combination of shape with demographics improved all estimates of boys and girls compared to the demographics-only model. The best prediction models for FMI, FFMI, and percent fat agreed with the actual measures with R2 adj. (the coefficient of determination adjusted for the number of parameters used in the model equation) values of 0.86, 0.95, and 0.75 for boys and 0.90, 0.89, and 0.69 for girls, respectively. Conclusions: Whole-body silhouettes in children may be useful to derive estimates of body composition including FMI, FFMI, and percent fat. These results support the feasibility of measuring body composition variables from simple

  12. Estimation of body composition of pigs

    SciTech Connect

    Ferrell, C.L.; Cornelius, S.G.

    1984-04-01

    A study was conducted to evaluate the use of deuterium oxide (D2O) for in vivo estimation of body composition of diverse types of pigs. Obese (Ob, 30) and contemporary Hampshire X Yorkshire (C, 30) types of pigs used in the study were managed and fed under typical management regimens. Indwelling catheters were placed in a jugular vein of 6 Ob and 6 C pigs at 4, 8, 12, 18 and 24 wk of age. The D2O was infused (.5 g/kg body weight) as a .9% NaCl solution into the jugular catheter. Blood samples were taken immediately before and at .25, 1, 4, 8, 12, 24 and 48 h after the D2O infusion and D2O concentration in blood water was determined. Pigs were subsequently killed by euthanasia injection. Contents of the gastrointestinal tract were removed and the empty body was then frozen and later ground and sampled for subsequent analyses. Ground body tissue samples were analyzed for water, fat, N, fat-free organic matter and ash. Pig type, age and the type X age interaction were significant sources of variation in live weight, D2O pool size and all empty body components, as well as all fat-free empty body components. Relationships between age and live weight or weight of empty body components, and between live weight, empty body weight, empty body water or D2O space and weight of empty components were highly significant but influenced, in most cases, by pig type. The results of this study suggested that, although relationships between D2O space and body component weights were highly significant, they were influenced by pig type and were little better than live weight for the estimation of body composition.

  13. A Study of Current Chopping Characteristics in Metal-Carbide Composite Contact Materials

    NASA Astrophysics Data System (ADS)

    Yamamoto, Atsushi; Kusano, Takashi; Okutomi, Tsutomu; Yokokura, Kunio; Homma, Mitsutaka

    To clarify the effect of carbides on current chopping characteristics chopping current was evaluated for various metalcarbide contact materials. As a result, it was found that the chopping current of metal-carbide contacts was related to the vapor pressure of metals and the work function of carbides. It was also found that the chopping current was reduced by the heat treatment when the melting point of contacts is lower than the temperature of heat teatment.

  14. Method Developed for Improving the Thermomechanical Properties of Silicon Carbide Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bhatt, Ramakrishna T.; DiCarlo, James A.

    2004-01-01

    Today, a major thrust for achieving engine components with improved thermal capability is the development of fiber-reinforced silicon-carbide (SiC) matrix composites. These materials are not only lighter and capable of higher use temperatures than state-of-the-art metallic alloys and oxide matrix composites (approx. 1100 C), but they can provide significantly better static and dynamic toughness than unreinforced silicon-based monolithic ceramics. However, for successful application in advanced engine systems, the SiC matrix composites should be able to withstand component service stresses and temperatures for the desired component lifetime. Since the high-temperature structural life of ceramic materials is typically controlled by creep-induced flaw growth, a key composite property requirement is the ability to display high creep resistance under these conditions. Also, because of the possibility of severe thermal gradients in the components, the composites should provide maximum thermal conductivity to minimize the development of thermal stresses. State-of-the-art SiC matrix composites are typically fabricated via a three-step process: (1) fabrication of a component-shaped architectural preform reinforced by high-performance fibers, (2) chemical vapor infiltration of a fiber coating material such as boron nitride (BN) into the preform, and (3) infiltration of a SiC matrix into the remaining porous areas in the preform. Generally, the highest performing composites have matrices fabricated by the CVI process, which produces a SiC matrix typically more thermally stable and denser than matrices formed by other approaches. As such, the CVI SiC matrix is able to provide better environmental protection to the coated fibers, plus provide the composite with better resistance to crack propagation. Also, the denser CVI SiC matrix should provide optimal creep resistance and thermal conductivity to the composite. However, for adequate preform infiltration, the CVI SiC matrix

  15. Top 10 Research Questions Related to Body Composition

    ERIC Educational Resources Information Center

    Going, Scott; Lee, Vinson; Blew, Rob; Laddu, Deepika; Hetherington-Rauth, Megan

    2014-01-01

    An understanding of body composition is crucial to understanding human health, disease, and function. Research in body composition has focused on the development of assessment methods, description of normal changes in body composition with growth and development and aging, and the changes that occur in body composition in response to challenges…

  16. Writing Bodies: Somatic Mind in Composition Studies.

    ERIC Educational Resources Information Center

    Fleckenstein, Kristie S.

    1999-01-01

    Discusses the somatic mind, a permeable materiality in which mind and body resolve into a single entity which is (re)formed by the constantly shifting boundaries of discursive and corporeal intertextualities. Addresses its importance in composition studies. Critiques the poststructuralist disregard of corporeality. (CR)

  17. Comparison of Some Secondary Body Composition Algorithms

    ERIC Educational Resources Information Center

    Sutton, Robert A.; Miller, Carolyn

    2006-01-01

    Body composition measurements vary greatly in degree of measurement difficulty and accuracy. Hydrostatic weighing, chemical dilution or their equivalents were the accepted "gold" standards for assessing fat mass. Dual Energy X-ray Absorptiometry (DEXA) is fast replacing these techniques as the preferred standard. However, these direct measurement…

  18. Recent advances and issues in development of silicon carbide composites for fusion applications

    SciTech Connect

    Nozawa, T.; Hinoki, Tetsuya; Hasegawa, Akira; Kohyama, Akira; Katoh, Yutai; Snead, Lance L.; Henager, Charles H.; Hegeman, Hans

    2009-04-30

    Radiation-resistant advanced silicon carbide composites (SiC/SiC) have been developed as a promising candidate of the high-temperature operating advanced fusion DEMO reactor. With the completion of the “proof-of-principle” phase in development of “nuclear-grade” SiC/SiC, the R&D on SiC/SiC is shifting toward the more pragmatic phase, i.e., industrialization of component manufactures and data-basing. In this paper, recent advances and issues in 1) development of component fabrication technology including joining and functional coating, e.g., a tungsten overcoat as a plasma facing barrier, 2) recent updates in characterization of non-irradiated properties, e.g., strength anisotropy and chemical compatibility with solid lithium-based ceramics and lead-lithium liquid metal breeders, and 3) irradiation effects were specifically reviewed. Importantly high-temperature neutron irradiation effects on microstructural evolution, thermal and electrical conductivities and mechanical properties including the fiber/matrix interfacial strength were specified under various irradiation conditions, indicating seemingly very minor influence on the composite performance in the design temperature range.

  19. Fatigue behavior of silicon carbide reinforced titanium (Ti/SCS-6) metal matrix composites

    SciTech Connect

    Liaw, P.K.; Diaz, E.S.; Chiang, K.T.; Loh, D.H.

    1995-05-15

    Flexure fatigue behavior was investigated on titanium (Ti-15V-3Cr) metal matrix composites reinforced with cross-poly, continuous silicon carbide (SiC) fibers. The Ti/SCS-6 composites had an 8-ply, (0{degree}, 90{degree}, +45{degree}, {minus}45{degree}), symmetric lay-up. During fatigue testing, four stages of flexure deflection behavior were observed. The deflection at stage 1 increased slightly with fatigue cycling, while that at stage 2 increased significantly with cycling. Interestingly, the deflection at stage 3 again increased negligibly with fatigue cycling. Stage 4 was associated with final failure, and the deflection increased abruptly. In the stage 1 region of the deflection behavior, no cracks were observed, the Ti/SiC interface debonding could be present, and the deflection changed slightly with cycling. When the stage 2 region commenced, cracks began to initiate. As stage 2 progressed, both crack density and crack length increased. The increased crack density and crack length contributed to the great increase in the deflection during stage 2. In stage 3, significant crack deflection and branching, and fiber bridging occurred, and crack density remained relatively constant. Crack deflection and branching, and fiber bridging slowed down crack driving force, and little crack extension was observed, which resulted in an insignificant amount of increase in the stage 3 deflection. The breakage of fibers in stage 4 significantly increased deflection.

  20. Time-Dependent Stress Rupture Strength Degradation of Hi-Nicalon Fiber-Reinforced Silicon Carbide Composites at Intermediate Temperatures

    NASA Technical Reports Server (NTRS)

    Sullivan, Roy M.

    2016-01-01

    The stress rupture strength of silicon carbide fiber-reinforced silicon carbide composites with a boron nitride fiber coating decreases with time within the intermediate temperature range of 700 to 950 degree Celsius. Various theories have been proposed to explain the cause of the time-dependent stress rupture strength. The objective of this paper is to investigate the relative significance of the various theories for the time-dependent strength of silicon carbide fiber-reinforced silicon carbide composites. This is achieved through the development of a numerically based progressive failure analysis routine and through the application of the routine to simulate the composite stress rupture tests. The progressive failure routine is a time-marching routine with an iterative loop between a probability of fiber survival equation and a force equilibrium equation within each time step. Failure of the composite is assumed to initiate near a matrix crack and the progression of fiber failures occurs by global load sharing. The probability of survival equation is derived from consideration of the strength of ceramic fibers with randomly occurring and slow growing flaws as well as the mechanical interaction between the fibers and matrix near a matrix crack. The force equilibrium equation follows from the global load sharing presumption. The results of progressive failure analyses of the composite tests suggest that the relationship between time and stress-rupture strength is attributed almost entirely to the slow flaw growth within the fibers. Although other mechanisms may be present, they appear to have only a minor influence on the observed time-dependent behavior.

  1. Effects of Fiber Coating Composition on Mechanical Behavior of Silicon Carbide Fiber-Reinforced Celsian Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Elderidge, Jeffrey I.

    1998-01-01

    Celsian matrix composites reinforced with Hi-Nicalon fibers, precoated with a dual layer of BN/SiC by chemical vapor deposition in two separate batches, were fabricated. Mechanical properties of the composites were measured in three-point flexure. Despite supposedly identical processing, the composite panels fabricated with fibers coated in two batches exhibited substantially different mechanical behavior. The first matrix cracking stresses (sigma(sub mc)) of the composites reinforced with fibers coated in batch 1 and batch 2 were 436 and 122 MPa, respectively. This large difference in sigma(sub mc) was attributed to differences in fiber sliding stresses(tau(sub friction)), 121.2+/-48.7 and 10.4+/-3.1 MPa, respectively, for the two composites as determined by the fiber push-in method. Such a large difference in values of tau(sub friction) for the two composites was found to be due to the difference in the compositions of the interface coatings. Scanning Auger microprobe analysis revealed the presence of carbon layers between the fiber and BN, and also between the BN and SiC coatings in the composite showing lower tau(sub friction). This resulted in lower sigma(sub mc) in agreement with the ACK theory. The ultimate strengths of the two composites, 904 and 759 MPa, depended mainly on the fiber volume fraction and were not significantly effected by tau(sub friction) values, as expected. The poor reproducibility of the fiber coating composition between the two batches was judged to be the primary source of the large differences in performance of the two composites.

  2. Effect of oxygen on the mechanical properties of copper and copper-matrix composites hardened by melt-synthesized chromium carbides

    NASA Astrophysics Data System (ADS)

    Babkin, V. G.; Trunova, A. I.; Cherepanov, A. I.

    2016-05-01

    Thermal analysis is used to study the saturation of the copper melt by oxygen from an oxygen-containing gas phase and the possibility of deoxidation of this melt by nanosized diamond-graphite, which enters in the reaction mixture used to synthesize chromium carbide in the production of copper-matrix composites, are studied. The oxygen and chromium carbide contents are found to affect the mechanical properties of copper and copper-matrix composites. Diamond-graphite is shown to have a high refining ability, which can substantially increase the plasticity of copper and copper-matrix composites. A low chromium carbide content is found to play a modifying role in grain refinement, and a high chromium carbide content is shown to cause the formation of a precipitation-hardened structure and an increase in the physicomechanical properties of copper-matrix composites.

  3. High-Performance Metal/Carbide Composites with Far-From-Equilibrium Compositions and Controlled Microstructures

    PubMed Central

    Hu, Liangfa; O’Neil, Morgan; Erturun, Veysel; Benitez, Rogelio; Proust, Gwénaëlle; Karaman, Ibrahim; Radovic, Miladin

    2016-01-01

    The prospect of extending existing metal-ceramic composites to those with the compositions that are far from thermodynamic equilibrium is examined. A current and pressure-assisted, rapid infiltration is proposed to fabricate composites, consisting of reactive metallic and ceramic phases with controlled microstructure and tunable properties. An aluminum (Al) alloy/Ti2AlC composite is selected as an example of the far-from-equilibrium systems to fabricate, because Ti2AlC exists only in a narrow region of the Ti-Al-C phase diagram and readily reacts with Al. This kind of reactive systems challenges conventional methods for successfully processing corresponding metal-ceramic composites. Al alloy/Ti2AlC composites with controlled microstructures, various volume ratios of constituents (40/60 and 27/73) and metallic phase sizes (42–83 μm, 77–276 μm, and 167–545 μm), are obtained using the Ti2AlC foams with different pore structures as preforms for molten metal (Al alloy) infiltration. The resulting composites are lightweight and display exceptional mechanical properties at both ambient and elevated temperatures. These structures achieve a compressive strength that is 10 times higher than the yield strength of the corresponding peak-aged Al alloy at ambient temperature and 14 times higher at 400 °C. Possible strengthening mechanisms are described, and further strategies for improving properties of those composites are proposed. PMID:27752106

  4. Skinfolds and body composition of sports participants.

    PubMed

    Gualdi Russo, E; Gruppioni, G; Gueresi, P; Belcastro, M G; Marchesini, V

    1992-09-01

    Body composition of 1815 North-Italian young sports participants in relation to sex, age, sport and level of performance was investigated. About thickness and anatomical distribution of subcutaneous fat females showed skinfolds thicker than males. Significant differences were observed in skinfold thicknesses means of different sport-groups. Subscapular and forearm skinfolds were the best discriminant variables for males and females respectively. Body density was estimated according to Katch and McArdle (1973) and Durnin and Womersley (1974) equations. Males showed higher body density and lower fat percentage values than females. The lowest value of body density and the highest fat percentage were in male martial art competitors and in females practising skating and athletics. The highest values of body density and the lowest of fat percentage were in males practising athletics and rowing and in female martial art competitors. Highest and lowest values of fat-free mass were in games players and in soccer players and gymnasts respectively. "High aptitude" subjects showed higher fat-free mass values than "middle aptitude" group, besides a tendency towards higher body density values and lower fat percentage than "middle aptitude" group. With aging body density decreased whereas fat percentage and fat-free mass increased.

  5. DEVELOPMENT OF ADVANCED DRILL COMPONENTS FOR BHA USING MICROWAVE TECHNOLOGY INCORPORATING CARBIDE, DIAMOND COMPOSITES AND FUNCTIONALLY GRADED MATERIALS

    SciTech Connect

    Dinesh Agrawal; Rustum Roy

    2003-01-01

    The microwave processing of materials is a new emerging technology with many attractive advantages over the conventional methods. The advantages of microwave technology for various ceramic systems has already been demonstrated and proven. The recent developments at Penn State have succeeded in applying the microwave technology for the commercialization of WC/Co and diamond based cutting and drilling tools, effectively sintering of metallic materials, and fabrication of transparent ceramics for advanced applications. In recent years, the Microwave Processing and Engineering Center at Penn State University in collaboration with our industrial partner, Dennis Tool Co. has succeeded in commercializing the developed microwave technology partially funded by DOE for WC/Co and diamond based cutting and drilling tools for gas and oil exploration operations. In this program we have further developed this technology to make diamond-carbide composites and metal-carbide-diamond functionally graded materials. Several actual product of diamond-carbide composites have been processed in microwave with better performance than the conventional product. The functionally graded composites with diamond as one of the components has been for the first time successfully developed. These are the highlights of the project.

  6. Body composition of athletes in Bahrain.

    PubMed Central

    Musaiger, A O; Ragheb, M A; al-Marzooq, G

    1994-01-01

    A total sample of 304 athletes was selected from first class clubs related to four common sports (football, handball, volleyball and basketball) and compared with 53 non-athlete adults. Weight, height, mid-arm circumference and skinfold thickness were measured to assess their body composition. The findings revealed that there were differences in body composition among athletes according to the type of sport. Basketballers and volleyballers were the tallest athletes, while handballers were the heaviest ones. Skinfold thickness measurements showed that basketball and handball players have more subcutaneous fat than other athletic groups. As compared with non-athletes, the Bahraini players had higher means for height, weight, subscapular, suprailliac thickness and mid-arm circumference. PMID:8000811

  7. Body composition of athletes in Bahrain.

    PubMed

    Musaiger, A O; Ragheb, M A; al-Marzooq, G

    1994-09-01

    A total sample of 304 athletes was selected from first class clubs related to four common sports (football, handball, volleyball and basketball) and compared with 53 non-athlete adults. Weight, height, mid-arm circumference and skinfold thickness were measured to assess their body composition. The findings revealed that there were differences in body composition among athletes according to the type of sport. Basketballers and volleyballers were the tallest athletes, while handballers were the heaviest ones. Skinfold thickness measurements showed that basketball and handball players have more subcutaneous fat than other athletic groups. As compared with non-athletes, the Bahraini players had higher means for height, weight, subscapular, suprailliac thickness and mid-arm circumference.

  8. Radiation-tolerant joining technologies for silicon carbide ceramics and composites

    SciTech Connect

    Katoh, Yutai; Snead, Lance L.; Cheng, Ting; Shih, Chunghao; Lewis, W. Daniel; Koyanagi, Takaaki; Hinoki, Tatsuya; Henager, Charles H.; Ferraris, Monica

    2014-05-01

    Silicon carbide (SiC) for nuclear structural applications, whether in the monolithic ceramic or composite form, will require a robust joining technology capable of withstanding the harsh nuclear environment. This paper presents significant progress made towards identifying and processing irradiation-tolerant joining methods for nuclear-grade SiC. In doing so, a standardized methodology for carrying out joint testing has been established consistent with the small volume samples mandated by neutron irradiation testing. Candidate joining technologies were limited to those that provide low induced radioactivity and included titanium diffusion bonding, Ti–Si–C MAX-phase joining, calcia–alumina glass–ceramic joining, and transient eutectic-phase SiC joining. Samples of these joints were irradiated in the Oak Ridge National Laboratory High Flux Isotope Reactor at 500 or 800 °C, and their microstructure and mechanical properties were compared to pre-irradiation conditions. Within the limitations of statistics, all joining methodologies presented retained their joint mechanical strength to ~3 dpa at 500 °C, thus indicating the first results obtained on irradiation-stable SiC joints. Finally, under the more aggressive irradiation conditions (800 °C, ~5 dpa), some joint materials exhibited significant irradiation-induced microstructural evolution; however, the effect of irradiation on joint strength appeared rather limited.

  9. Suspension Plasma Spraying of Sub-micron Silicon Carbide Composite Coatings

    NASA Astrophysics Data System (ADS)

    Mubarok, F.; Espallargas, N.

    2015-06-01

    Thermal spraying of silicon carbide (SiC) material is a challenging task since SiC tends to decompose during atmospheric spraying process. The addition of metal or ceramic binders is necessary to facilitate the bonding of SiC particles, allowing SiC composite coating to be deposited. In the conventional procedures, the binders are added through mechanical mixing of powder constituents, making it difficult to achieve homogeneous distribution. In the new procedure proposed in this work, the binder is delivered as a nano-film of the surface of the individual SiC particles through co-precipitation treatment. Suspension plasma spray (SPS) coating technique has been used with the aim at avoiding the decomposition of SiC typically expected with atmospheric techniques, such as atmospheric plasma spray. The deposited SiC coatings by SPS showed identical SiC phase peak as identified in the suspension feedstock, indicating that the nano-film binder was able to protect SiC particles from decomposition. Further analysis by XPS revealed that SiC particles underwent some minor oxidation. Unfortunately, all the SiC coatings exhibited poor mechanical performance due to low cohesive strength, high porosity, and powdery structure making the coatings vulnerable to grain pull-out. This was due to the absence of sintering process during the spraying process contributing to the low performance of SiC SPS coatings.

  10. Two-Dimensional Titanium Carbide/RGO Composite for High-Performance Supercapacitors.

    PubMed

    Zhao, Chongjun; Wang, Qian; Zhang, Huang; Passerini, Stefano; Qian, Xiuzhen

    2016-06-22

    Ti3C2Tx, a 2D titanium carbide in the MXenes family, is obtained from Ti3AlC2 through selective etching of the Al layer. Due to its good conductivity and high volumetric capacitance, Ti3C2Tx is regarded as a promising candidate for supercapacitors. In this paper, the fabrication of Ti3C2Tx/RGO composites with different proportions of Ti3C2Tx and RGO is reported, in which RGO acts as a conductive "bridge" to connect different Ti3C2Tx blocks and a matrix to alleviate the volume change during charge/discharge process. In addition, RGO nanosheets can serve as a second nanoscale current collector and support as well for the electrode. The electrochemical performance of the as-fabricated Ti3C2Tx/RGO electrodes, characterized by CV, GCD, and EIS, are also reported. A highest specific capacitance (Cs) of 154.3 F/g at 2 A/g is obtained at the Ti3C2Tx: RGO weight ratio of 7:1 combined with an outstanding capacity retention (124.7 F/g) after 6000 cycles at 4 A/g.

  11. Steady State Sputtering Yields and Surface Compositions of Depleted Uranium and Uranium Carbide bombarded by 30 keV Gallium or 16 keV Cesium Ions.

    SciTech Connect

    Siekhaus, W. J.; Teslich, N. E.; Weber, P. K.

    2014-10-23

    Depleted uranium that included carbide inclusions was sputtered with 30-keV gallium ions or 16-kev cesium ions to depths much greater than the ions’ range, i.e. using steady-state sputtering. The recession of both the uranium’s and uranium carbide’s surfaces and the ion corresponding fluences were used to determine the steady-state target sputtering yields of both uranium and uranium carbide, i.e. 6.3 atoms of uranium and 2.4 units of uranium carbide eroded per gallium ion, and 9.9 uranium atoms and 3.65 units of uranium carbide eroded by cesium ions. The steady state surface composition resulting from the simultaneous gallium or cesium implantation and sputter-erosion of uranium and uranium carbide were calculated to be U₈₆Ga₁₄, (UC)₇₀Ga₃₀ and U₈₁Cs₉, (UC)₇₉Cs₂₁, respectively.

  12. The material performance of HSS (high speed steel) tools and its relation with chemical composition and carbide distribution

    NASA Astrophysics Data System (ADS)

    Darmawan, B.; Kusman, M.; Hamdani, R. A.

    2016-04-01

    The study aims to compare the performance of two types of material HSS (High Speed Steel) are widely used. It also will be the chemical composition and distribution of carbide particles therein. Two types of HSS are available in the market: HSS from Germany (Bohler) and HSS from China. This research employed the pure experimental design. It consists of two stages. The first, aims to test/operate lathe machines to determine the lifetime and performance of tools based on specified wear criteria. The second, characterization of microstructure using SEM-EDS was conducted. Firstly, grinding of toolss was done so that the toolss could be used for cutting metal in the turning process. Grinding processes of the two types of toolss were done at the same geometry, that is side rake angle (12°-18°), angle of keenness (60°-68°), and side relief angle (10°-12°). Likewise, machining parameters were set in the same machining conditions. Based on the results of the tests, it is found that to reach 0.2 mm wear point, toolss made of HSS from Germany needed 24 minutes, while toolss made of HSS from China needed 8 minutes. Next, microstructure tests using SEM/EDS were done. The results of the SEM tests indicate that the carbide particles of HSS from Germany were more evenly distributed than the carbide particles of HSS from China. Carbide compounds identified in HSS from China were Cr23C6 and Fe4Mo2C. Oxide impurity of Al2O3 was also found in the material. On the other hand, in HSS from Germany, no impurity and other carbide compounds were identified, except Cr23C6 and Fe4Mo2C, also Fe4W2C, and VC or V4C3.

  13. Reaction-Based SiC Materials for Joining Silicon Carbide Composites for Fusion Energy

    SciTech Connect

    Lewinsohn, Charles A.; Jones, Russell H.; Singh, M.; Serizawa, H.; Katoh, Y.; Kohyama, A.

    2000-09-01

    The fabrication of large or complex silicon carbide-fiber-reinforced silicon carbide (SiC/SiC) components for fusion energy systems requires a method to assemble smaller components that are limited in size by manufacturing constraints. Previous analysis indicates that silicon carbide should be considered as candidate joint materials. Two methods to obtain SiC joints rely on a reaction between silicon and carbon to produce silicon carbide. This report summarizes preliminary mechanical properties of joints formed by these two methods. The methods appear to provide similar mechanical properties. Both the test methods and materials are preliminary in design and require further optimization. In an effort to determine how the mechanical test data is influenced by the test methodology and specimen size, plans for detailed finite element modeling (FEM) are presented.

  14. The Body and the Beautiful: Health, Attractiveness and Body Composition in Men's and Women's Bodies.

    PubMed

    Brierley, Mary-Ellen; Brooks, Kevin R; Mond, Jonathan; Stevenson, Richard J; Stephen, Ian D

    2016-01-01

    The dominant evolutionary theory of physical attraction posits that attractiveness reflects physiological health, and attraction is a mechanism for identifying a healthy mate. Previous studies have found that perceptions of the healthiest body mass index (weight scaled for height; BMI) for women are close to healthy BMI guidelines, while the most attractive BMI is significantly lower, possibly pointing to an influence of sociocultural factors in determining attractive BMI. However, less is known about ideal body size for men. Further, research has not addressed the role of body fat and muscle, which have distinct relationships with health and are conflated in BMI, in determining perceived health and attractiveness. Here, we hypothesised that, if attractiveness reflects physiological health, the most attractive and healthy appearing body composition should be in line with physiologically healthy body composition. Thirty female and 33 male observers were instructed to manipulate 15 female and 15 male body images in terms of their fat and muscle to optimise perceived health and, separately, attractiveness. Observers were unaware that they were manipulating the muscle and fat content of bodies. The most attractive apparent fat mass for female bodies was significantly lower than the healthiest appearing fat mass (and was lower than the physiologically healthy range), with no significant difference for muscle mass. The optimal fat and muscle mass for men's bodies was in line with the healthy range. Male observers preferred a significantly lower overall male body mass than did female observers. While the body fat and muscle associated with healthy and attractive appearance is broadly in line with physiologically healthy values, deviations from this pattern suggest that future research should examine a possible role for internalization of body ideals in influencing perceptions of attractive body composition, particularly in women. PMID:27257677

  15. COMPOSITION AND METHOD FOR COATING A CERAMIC BODY

    DOEpatents

    Blanchard, M.K.

    1958-11-01

    A method is presented for protecting a beryllium carbide-graphite body. The method consists in providing a ceramic coating which must contain at least one basic oxide component, such as CaO, at least one amphoteric oxide component, such as Al/sub 2/O/sub 3/, and at least one acidic oxide component, such as SiO/ sub 2/. Various specific formulations for this ceramic coating are given and the coating is applied by conventional ceramic techniques.

  16. Diorganosilacetylene-alt-diorganosilvinylene polymers and a process densifying porous silicon-carbide bodies

    DOEpatents

    Barton, Thomas J.; Ijadi-Maghsoodi, Sina; Pang, Yi

    1994-05-17

    The present invention provides linear organosilicon polymers including acetylene and vinylene moieties, and a process for their preparation. These diorganosilacetylene-alt-diorganosilvinylene linear polymers can be represented by the formula: --[--(R.sup.1)(R.sup.2)Si--C.tbd.C--(R.sup.3)(R.sup.4)Si--CH=CH--].sub.n-- , wherein n.gtoreq.2; and each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is independently selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, aryl, and aralkyl radicals. The polymers are soluble in organic solvents, air stable, and can be pulled into fibers or cast into films. They can be thermally converted into silicon carbide ceramic materials.

  17. Diorganosilacetylene-alt-diorganosilvinylene polymers and a process densifying porous silicon-carbide bodies

    DOEpatents

    Barton, T.J.; Ijadi-Maghsoodi, S.; Pang, Y.

    1994-05-17

    The present invention provides linear organosilicon polymers including acetylene and vinylene moieties, and a process for their preparation. These diorganosilacetylene-alt-diorganosilvinylene linear polymers can be represented by the formula: --[--(R[sup 1])(R[sup 2])Si--C[triple bond]C-(R[sup 3])(R[sup 4])Si--CH[double bond]CH--][sub n]--, wherein n[>=]2; and each R[sup 1], R[sup 2], R[sup 3], and R[sup 4] is independently selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, aryl, and aralkyl radicals. The polymers are soluble in organic solvents, air stable, and can be pulled into fibers or cast into films. They can be thermally converted into silicon carbide ceramic materials.

  18. Method for production of ceramic oxide and carbide bodies by polymer inclusion and decomposition

    DOEpatents

    Quinby, T.C.

    1984-08-30

    A method for the preparation of thin, free-standing metal oxide films which are useful as nuclear accelerator target materials is described. Cations of any metal except those of Group IA and precious metals, such as, U, Zr, Nd, Ce, Th, Pr or Cr, are absorbed on a thin film of polymeric material, such as carboxymethylcellulose, viscose rayon or cellophane. The cation impregnated polymeric material is dried. Then the impregnated film is heated in an inert atmosphere to form a carbonized membrane. The carbonized membrane is oxidized to yield a thin, self-supporting, metal oxide membrane. Or, the membrane can be heated in an inert atmosphere to yield a thin, self-supporting, metal carbide-containing membrane.

  19. Method for production of ceramic oxide and carbide bodies by polymer inclusion and decomposition

    DOEpatents

    Quinby, Thomas C.

    1985-01-01

    A method for the preparation of thin, free-standing metal oxide films which are useful as nuclear accelerator target materials. Cations of any metal except those of Group IA and precious metals, such as, U, Zr, Nd, Ce, Th, pr or Cr, are absorbed on a thin film of polymeric material, such as, carboxymethylcellulose, viscose rayon or cellophane. The cation impregnated polymeric material is dried. Then the impregnated film is heated in an inert atmosphere to form a carbonized membrane. The carbonized membrane is oxidized to yield a thin, self-supporting, metal oxide membrane. Or, the membrane can be heated in an inert atmosphere to yield a thin, self-supporting, metal carbide-containing membrane.

  20. Method for production of ceramic oxide and carbide bodies by polymer inclusion and decomposition

    SciTech Connect

    Quinby, T. C.

    1985-08-27

    A method for the preparation of thin, free-standing metal oxide films which are useful as nuclear accelerator target materials. Cations of any metal except those of Group IA and precious metals, such as, U, Zr, Nd, Ce, Th, pr or Cr, are absorbed on a thin film of polymeric material, such as, carboxymethylcellulose, viscose rayon or cellophane. The cation impregnated polymeric material is dried. Then the impregnated film is heated in an inert atmosphere to form a carbonized membrane. The carbonized membrane is oxidized to yield a thin, self-supporting, metal oxide membrane. Or, the membrane can be heated in an inert atmosphere to yield a thin, self-supporting, metal carbide-containing membrane.

  1. Effects of chronic acceleration on body composition

    NASA Technical Reports Server (NTRS)

    Pitts, G. C.

    1982-01-01

    Studies of the centrifugation of adult rats showed an unexpected decrease in the mass of fat-free muscle and bone, in spite of the added load induced by centrifugation. It is suggested that the lower but constant fat-free body mass was probably regulated during centrifugation. Rats placed in weightless conditions for 18.5 days gave indirect but strong evidence that the muscle had increased in mass. Other changes in the rats placed in weightless conditions included a smaller fraction of skeletal mineral, a smaller fraction of water in the total fat-free body, and a net shift of fluid from skin to viscera. Adult rats centrifuged throughout the post-weaning growth period exhibited smaller masses of bone and central nervous system (probably attributable to slower growth of the total body), and a larger mass of skin than controls at 1 G. Efforts at simulating the effects of weightlessness or centrifugation on the body composition of rats by regimens at terrestrial gravity were inconclusive.

  2. Recent achievements using chemical vapor composite silicon carbide (CVC SiC)

    NASA Astrophysics Data System (ADS)

    Goodman, William A.; Tanaka, Clifford

    2009-08-01

    This annual review documents our progress towards inexpensive mass production of silicon carbide mirrors and optical structures. Results are provided for a NASA Small Business Technology Transfer (STTR) X-Ray Mirror project. Trex partnered with the University of Alabama-Huntsville Center for Advanced Optics (UAH-CAO) to develop fabrication methods for polished cylindrical and conical chemical vapor composite (CVCTM) SiC mandrels. These mandrels are envisioned as pre-forms for the replication of fused silica x-ray optics to be eventually used in the International X-Ray Observatory (IXO). CVC SiCTM offers superior high temperature stability, thermal and mechanical performance and polishability required for this precision replication process. In this program, Trex fabricated prototype mandrels with design diameters of 10.5cm, 20cm and 45cm. UAH-CAO was Trex's university partner in this effort and worked on polishing and metrology of the unusual x-ray mandrel geometries. UAH-CAO successfully developed an innovative interferometric method for measuring the CVC SiCTM x-ray mandrels based on a precision cylindrical lens system. UAH-CAO also developed finishing and polishing methods for CVC SiCTM that utilized a Zeeko IRP200 computer controlled polishing tool. The three technologies key technologies demonstrated in this program (near net shape forming of CVC SiCTM mandrels, the x-ray mandrel metrology and free-form polishing capability on CVC SiCTM) could enable cost-effective manufacture of the x-ray mandrels required for the International X-Ray Observatory (IXO).

  3. New environmental barrier coating system on carbon-fiber reinforced silicon carbide composites

    NASA Astrophysics Data System (ADS)

    Latzel, S.; Vaßen, R.; Stöver, D.

    2005-06-01

    Carbon-fiber-reinforced silicon carbide composites (C/SiC) are promising materials for high-temperature, light weight structural components. However, a protective coating and environmental barrier coating (EBC) are necessary to prevent the oxidation of the carbon and the reaction of the formed silica scale with water vapor. Current EBC systems use multiple layers, each serving unique requirements. However, any mismatch in the coefficients of thermal expansion (CTE) creates internal stresses and might lead to crack formation. In this case, oxygen and water vapor penetrate through the EBC, reducing the lifetime of the component. Mullite (Al6Si2O13) is used in many known EBC systems on silicon-based ceramics either as an EBC itself or as a bondcoat. Due to its low CTE and its sufficient thermal cycling behavior, mullite was chosen in this investigation as a first layer. As mullite suffers loss of SiO2 when exposed to water vapor at high temperatures, an additional protective top coat is needed to complete the EBC system. Different oxides were evaluated to serve as top coat, especially high-temperature oxides with low coefficients of thermal expansion (LCTE). An EBC containing mullite as bondcoat and the LCTE oxide La2Hf2O7 as a top coat is proposed. Both layers were applied via atmospheric plasma spraying. In this paper, results of the influence of processing conditions on the microstructure of single mullite and LCTE oxide layers as well as mullite/LCTE oxide systems are presented. Special emphasis was directed toward the crystallinity of the mullite layer and, in the top layer, toward low porosity and reduced crack density.

  4. Assessment of Silicon Carbide Composites for Advanced Salt-Cooled Reactors

    SciTech Connect

    Katoh, Yutai; Wilson, Dane F; Forsberg, Charles W

    2007-09-01

    The Advanced High-Temperature Reactor (AHTR) is a new reactor concept that uses a liquid fluoride salt coolant and a solid high-temperature fuel. Several alternative fuel types are being considered for this reactor. One set of fuel options is the use of pin-type fuel assemblies with silicon carbide (SiC) cladding. This report provides (1) an initial viability assessment of using SiC as fuel cladding and other in-core components of the AHTR, (2) the current status of SiC technology, and (3) recommendations on the path forward. Based on the analysis of requirements, continuous SiC fiber-reinforced, chemically vapor-infiltrated SiC matrix (CVI SiC/SiC) composites are recommended as the primary option for further study on AHTR fuel cladding among various industrially available forms of SiC. Critical feasibility issues for the SiC-based AHTR fuel cladding are identified to be (1) corrosion of SiC in the candidate liquid salts, (2) high dose neutron radiation effects, (3) static fatigue failure of SiC/SiC, (4) long-term radiation effects including irradiation creep and radiation-enhanced static fatigue, and (5) fabrication technology of hermetic wall and sealing end caps. Considering the results of the issues analysis and the prospects of ongoing SiC research and development in other nuclear programs, recommendations on the path forward is provided in the order or priority as: (1) thermodynamic analysis and experimental examination of SiC corrosion in the candidate liquid salts, (2) assessment of long-term mechanical integrity issues using prototypical component sections, and (3) assessment of high dose radiation effects relevant to the anticipated operating condition.

  5. Carbide coated fibers in graphites-aluminum composites. [(fabrication of metal matrix composites)

    NASA Technical Reports Server (NTRS)

    Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

    1976-01-01

    Research activities are described for a NASA-supported program at the Los Alamos Scientific Laboratory to develop graphite fiber-aluminum matrix composites. A chemical vapor deposition apparatus was constructed for continuously coating graphite fibers with TiC. As much as 150 meters of continuously coated fibers were produced. Deposition temperatures were varied from 1365 K to about 1750 K, and deposition time from 6 to 150 seconds. The 6 sec deposition time corresponded to a fiber feed rate of 2.54 m/min through the coater. Thin, uniform, adherent TiC coats, with thicknesses up to approximately 0.1 micrometer were produced on the individual fibers of Thornel 50 graphite yarns without affecting fiber strength. Although coat properties were fairly uniform throughout a given batch, more work is needed to improve the batch-to-batch reproducibility. Samples of TiC-coated Thornel 50 fibers were infiltrated with an aluminum alloy and hot-pressed in vacuum to produce small composite bars for flexure testing. Strengths as high as 90% of the rule-of-mixtures strength were achieved. Results of the examination of the fracture surfaces indicate that the bonding between the aluminum and the TiC-coated fibers is better than that achieved in a similar, commercially infiltrated material made with fibers having no observable surface coats. Several samples of Al-infiltrated, TiC-coated Thornel 50 graphite yarns, together with samples of the commercially infiltrated, uncoated fibers, were heated for 100 hours at temperatures near the alloy solidus. The TiC-coated samples appear to undergo less reaction than do the uncoated samples. Photomicrographs are shown.

  6. Composites comprising silicon carbide fibers dispersed in magnesia-aluminate matrix and fabrication thereof and of other composites by sinter forging

    DOEpatents

    Panda, Prakash C.; Seydel, Edgar R.; Raj, Rishi

    1989-10-03

    A novel ceramic-ceramic composite of a uniform dispersion of silicon carbide fibers in a matrix of MgO.multidot.nAl.sub.2 O.sub.3 wherein n ranges from about 1 to about 4.5, said composite comprising by volume from 1 to 50% silicon carbide fibers and from 99 to 50% MgO.multidot.nAl.sub.2 O.sub.3. The composite is readily fabricated by forming a powder comprising a uniform dispersion of silicon carbide fibers in poorly crystalline phase comprising MgO and Al.sub.2 O.sub.3 in a mole ratio of n and either (a) hot pressing or preferably (b) cold pressing to form a preform and then forging utilizing a temperature in the range of 1100.degree. C. to 1900.degree. C. and a strain rate ranging from about 10.sup.-5 seconds .sup.-1 to about 1 seconds .sup.-1 so that surfaces cracks do not appear to obtain a shear deformation greater than 30%.

  7. Body composition in remission of childhood cancer

    NASA Astrophysics Data System (ADS)

    Tseytlin, G. Ja; Anisimova, A. V.; Godina, E. Z.; Khomyakova, I. A.; Konovalova, M. V.; Nikolaev, D. V.; Rudnev, S. G.; Starunova, O. A.; Vashura, A. Yu

    2012-12-01

    Here, we describe the results of a cross-sectional bioimpedance study of body composition in 552 Russian children and adolescents aged 7-17 years in remission of various types of cancer (remission time 0-15 years, median 4 years). A sample of 1500 apparently healthy individuals of the same age interval was used for comparison. Our data show high frequency of malnutrition in total cancer patients group depending on type of cancer. 52.7% of patients were malnourished according to phase angle and percentage fat mass z-score with the range between 42.2% in children with solid tumors located outside CNS and 76.8% in children with CNS tumors. The body mass index failed to identify the proportion of patients with malnutrition and showed diagnostic sensitivity 50.6% for obesity on the basis of high percentage body fat and even much less so for undernutrition - 13.4% as judged by low phase angle. Our results suggest an advantage of using phase angle as the most sensitive bioimpedance indicator for the assessment of metabolic alterations, associated risks, and the effectiveness of rehabilitation strategies in childhood cancer patients.

  8. Effect of body composition methodology on heritability estimation of body fatness

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heritability estimates of human body fatness vary widely and the contribution of body composition methodology to this variability is unknown. The effect of body composition methodology on estimations of genetic and environmental contributions to body fatness variation was examined in 78 adult male ...

  9. Tribological composition optimization of chromium-carbide-based solid lubricant coatings for foil gas bearings at temperatures to 650 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher

    1988-01-01

    The determination of the tribilogically optimum composition of chromium-carbide-based solid lubricant coatings using a foil gas bearing test apparatus is described. The coatings contain a wear resistant chromium carbide `base stock' with the lubricant additives silver and BaF2-CaF2 eutectic. The coating composition is optimized for air-lubricated foil gas bearings at temperatures ranging from 25 to 650 C. The various compositions were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized Ni-Cr alloy foils, and the test bearings were subjected to repeated start-stop cycles under a bearing unit of 14 kPa. Sliding contact between the coated journal and the smooth foil occurs during bearing start-up before lift-off or hydrodynamic lubrication by the air film and during bearing coast-down. The bearings were tested for 9000 start-stop cycles or until specimen reached a predetermined failure level.

  10. Cryogenic optical measurements of 12-segment-bonded carbon-fiber-reinforced silicon carbide composite mirror with support mechanism.

    PubMed

    Kaneda, Hidehiro; Nakagawa, Takao; Onaka, Takashi; Enya, Keigo; Makiuti, Sin'itirou; Takaki, Junji; Haruna, Masaki; Kume, Masami; Ozaki, Tsuyoshi

    2008-03-10

    A 720 mm diameter 12-segment-bonded carbon-fiber-reinforced silicon carbide (C/SiC) composite mirror has been fabricated and tested at cryogenic temperatures. Interferometric measurements show significant cryogenic deformation of the C/SiC composite mirror, which is well reproduced by a model analysis with measured properties of the bonded segments. It is concluded that the deformation is due mostly to variation in coefficients of thermal expansion among segments. In parallel, a 4-degree-of-freedom ball-bearing support mechanism has been developed for cryogenic applications. The C/SiC composite mirror was mounted on an aluminum base plate with the support mechanism and tested again. Cryogenic deformation of the mirror attributed to thermal contraction of the aluminum base plate via the support mechanism is highly reduced by the support, confirming that the newly developed support mechanism is promising for its future application to large-aperture cooled space telescopes.

  11. Boron carbide: Consistency of components, lattice parameters, fine structure and chemical composition makes the complex structure reasonable

    NASA Astrophysics Data System (ADS)

    Werheit, Helmut

    2016-10-01

    The complex, highly distorted structure of boron carbide is composed of B12 and B11C icosahedra and CBC, CBB and B□B linear elements, whose concentration depends on the chemical composition each. These concentrations are shown to be consistent with lattice parameters, fine structure data and chemical composition. The respective impacts on lattice parameters are estimated and discussed. Considering the contributions of the different structural components to the energy of the overall structure makes the structure and its variation within the homogeneity range reasonable; in particular that of B4.3C representing the carbon-rich limit of the homogeneity range. Replacing in B4.3C virtually the B□B components by CBC yields the hypothetical moderately distorted B4.0C (structure formula (B11C)CBC). The reduction of lattice parameters related is compatible with recently reported uncommonly prepared single crystals, whose compositions deviate from B4.3C.

  12. Cryogenic optical measurements of 12-segment-bonded carbon-fiber-reinforced silicon carbide composite mirror with support mechanism

    NASA Astrophysics Data System (ADS)

    Kaneda, Hidehiro; Nakagawa, Takao; Onaka, Takashi; Enya, Keigo; Makiuti, Sin'itirou; Takaki, Junji; Haruna, Masaki; Kume, Masami; Ozaki, Tsuyoshi

    2008-03-01

    A 720 mm diameter 12-segment-bonded carbon-fiber-reinforced silicon carbide (C/SiC) composite mirror has been fabricated and tested at cryogenic temperatures. Interferometric measurements show significant cryogenic deformation of the C/SiC composite mirror, which is well reproduced by a model analysis with measured properties of the bonded segments. It is concluded that the deformation is due mostly to variation in coefficients of thermal expansion among segments. In parallel, a 4-degree-of-freedom ball-bearing support mechanism has been developed for cryogenic applications. The C/SiC composite mirror was mounted on an aluminum base plate with the support mechanism and tested again. Cryogenic deformation of the mirror attributed to thermal contraction of the aluminum base plate via the support mechanism is highly reduced by the support, confirming that the newly developed support mechanism is promising for its future application to large-aperture cooled space telescopes.

  13. Composition optimization of chromium carbide based solid lubricant coatings for foil gas bearings at temperatures to 650 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher

    1987-01-01

    A test program to determine the optimum composition of chromium carbide based solid lubricant coatings for compliant gas bearings is described. The friction and wear properties of the coatings are evaluated using a foil gas bearing test apparatus. The various coatings were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized nickel-chromium alloy foils. The test bearings were subjected to repeated start/stop cycles under a 14 kPa (2 psi) bearing unit load. The bearings were tested for 9000 start/stop cycles or until the specimen wear reached a predetermined failure level. In general, the addition of silver and eutectic to the chromium carbide base stock significantly reduced foil wear and increased journal coating wear. The optimum coating composition, PS212 (70 wt% metal bonded Cr3C2, 15 wt% Ag, 15% BaF2/CaF2 eutectic), reduced foil wear by a factor of two and displayed coating wear well within acceptable limits. The load capacity of the bearing using the plasma-sprayed coating prior to and after a run-in period was ascertained and compared to polished Inconel 718 specimens.

  14. Effects of Whole Body Vibration Training on Body Composition in Adolescents with Down Syndrome

    ERIC Educational Resources Information Center

    Gonzalez-Aguero, Alejandro; Matute-Llorente, Angel; Gomez-Cabello, Alba; Casajus, Jose A.; Vicente-Rodriguez, German

    2013-01-01

    The present study aimed to determine the effect of 20 weeks of whole body vibration (WBV) on the body composition of adolescents with Down syndrome (DS). Thirty adolescent with DS were divided into two groups: control and WBV. Whole body, upper and lower limbs body fat and lean body mass were measured with dual energy X-ray absorptiometry (DXA)…

  15. High Dose Neutron Irradiation of Hi-Nicalon Type S Silicon Carbide Composites, Part 2. Mechanical and Physical Properties

    SciTech Connect

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao Phillip; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wallace D; Snead, Lance Lewis

    2015-01-07

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573–1073 K. Likewise, the material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating the irradiation temperature, but only to a limited extent. Moreover, the observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.

  16. High-dose neutron irradiation of Hi-Nicalon Type S silicon carbide composites. Part 2: Mechanical and physical properties

    NASA Astrophysics Data System (ADS)

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wally; Snead, Lance L.

    2015-07-01

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573-1073 K. The material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating the irradiation temperature, but only to a limited extent. The observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.

  17. Body Composition and Somatotype of Male and Female Nordic Skiers

    ERIC Educational Resources Information Center

    Sinning, Wayne E.; And Others

    1977-01-01

    Anthropometric measurements (body composition and somatotype characteristics) for male and female Nordic skiers showed small values for measures of variance, suggesting that the subjects represented a select body type for the sport. (Author/MJB)

  18. DEVELOPMENT OF ADVANCED DRILL COMPONENTS FOR BHA USING MICROWAVE TECHNOLOGY INCORPORATING CARBIDE, DIAMOND COMPOSITES AND FUNCTIONALLY GRADED MATERIALS

    SciTech Connect

    Dinesh Agrawal; Rustum Roy

    2000-11-01

    The main objective of this program was to develop an efficient and economically viable microwave processing technique to process cobalt cemented tungsten carbide with improved properties for drill-bits for advanced drilling operations for oil, gas, geothermal and excavation industries. The program was completed in three years and successfully accomplished all the states goals in the original proposal. In three years of the program, we designed and built several laboratory scale microwave sintering systems for conducting experiments on Tungsten carbide (WC) based composites in controlled atmosphere. The processing conditions were optimized and various properties were measured. The design of the system was then modified to enable it to process large commercial parts of WC/Co and in large quantities. Two high power (3-6 kW) microwave systems of 2.45 GHz were built for multi samples runs in a batch process. Once the process was optimized for best results, the technology was successfully transferred to our industrial partner, Dennis Tool Co. We helped them to built couple of prototype microwave sintering systems for carbide tool manufacturing. It was found that the microwave processed WC/Co tools are not only cost effective but also exhibited much better overall performance than the standard tools. The results of the field tests performed by Dennis Tool Co. showed remarkable advantage and improvement in their overall performance. For example: wear test shows an increase of 20-30%, corrosion test showed much higher resistance to the acid attack, erosion test exhibited about 15% better resistance than standard sinter-HIP parts. This proves the success of microwave technology for WC/Co based drilling tools. While we have successfully transferred the technology to our industrial partner Dennis Tool Co., they have signed an agreement with Valenite, a world leading WC producer of cutting and drilling tools and wear parts, to push aggressively the new microwave technology in

  19. Rat body size, composition and growth at hypo- and hypergravity

    NASA Technical Reports Server (NTRS)

    Pitts, G. C.

    1983-01-01

    The effects of hypergravity (centrifugation) on body composition were investigated. Hypogravitational and hypergravitational aspects were reflected in the research effort. A list of publications is provided.

  20. REVIEW: Development of methods for body composition studies

    NASA Astrophysics Data System (ADS)

    Mattsson, Sören; Thomas, Brian J.

    2006-07-01

    This review is focused on experimental methods for determination of the composition of the human body, its organs and tissues. It summarizes the development and current status of fat determinations from body density, total body water determinations through the dilution technique, whole and partial body potassium measurements for body cell mass estimates, in vivo neutron activation analysis for body protein measurements, dual-energy absorptiometry (DEXA), computed tomography (CT) and magnetic resonance imaging (MRI, fMRI) and spectroscopy (MRS) for body composition studies on tissue and organ levels, as well as single- and multiple-frequency bioimpedance (BIA) and anthropometry as simple easily available methods. Methods for trace element analysis in vivo are also described. Using this wide range of measurement methods, together with gradually improved body composition models, it is now possible to quantify a number of body components and follow their changes in health and disease.

  1. Characterization of anisotropie elastic constants of silicon-carbide participate reinforced aluminum metal matrix composites: Part I. Experiment

    NASA Astrophysics Data System (ADS)

    Jeong, Hyunjo; Hsu, David K.; Shannon, Robert E.; Liaw, Peter K.

    1994-04-01

    The anisotropic elastic properties of silicon-carbide particulate (SiC p ) reinforced Al metal matrix composites were characterized using ultrasonic techniques and microstructural analysis. The composite materials, fabricated by a powder metallurgy extrusion process, included 2124, 6061, and 7091 Al alloys reinforced by 10 to 30 pct of α-SiC p by volume. Results were presented for the assumed orthotropic elastic constants obtained from ultrasonic velocities and for the microstructural data on particulate shape, aspect ratio, and orientation distribution. All of the composite samples exhibited a systematic anisotropy: the stiffness in the extrusion direction was the highest, and the stiffness in the out-of-plane direction was the lowest. Microstructural analysis suggested that the observed anisotropy could be attributed to the preferred orientation of SiC p . The ultrasonic velocity was found to be sensitive to internal defects such as porosity and intermetallic compounds. It has been observed that ultrasonics may be a useful, nondestructive technique for detecting small directional differences in the overall elastic constants of the composites since a good correlation has been noted between the velocity and microstructure and the mechanical test. By incorporating the observed microstructural characteristics, a theoretical model for predicting the anisotropic stiffnesses of the composites has been developed and is presented in a companion article (Part II).

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

    SciTech Connect

    Perez-Bergquist, Alex G.; Nozawa, Takashi; Shih, Chunghao Phillip; Leonard, Keith J.; Snead, Lance Lewis; Katoh, Yutai

    2014-07-01

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

  3. The preparation and performance of calcium carbide-derived carbon/polyaniline composite electrode material for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zheng, Liping; Wang, Ying; Wang, Xianyou; Li, Na; An, Hongfang; Chen, Huajie; Guo, Jia

    Calcium carbide (CaC 2)-derived carbon (CCDC)/polyaniline (PANI) composite materials are prepared by in situ chemical oxidation polymerization of an aniline solution containing well-dispersed CCDC. The structure and morphology of CCDC/PANI composite are characterized by Fourier infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM) and N 2 sorption isotherms. It has been found that PANI was uniformly deposited on the surface and the inner pores of CCDC. The supercapacitive behaviors of the CCDC/PANI composite materials are investigated with cyclic voltammetry (CV), galvanostatic charge/discharge and cycle life measurements. The results show that the CCDC/PANI composite electrodes have higher specific capacitances than the as grown CCDC electrodes and higher stability than the conducting polymers. The capacitance of CCDC/PANI composite electrode is as high as 713.4 F g -1 measured by cyclic voltammetry at 1 mV s -1. Besides, the capacitance retention of coin supercapacitor remained 80.1% after 1000 cycles.

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

    DOE PAGESBeta

    Perez-Bergquist, Alex G.; Nozawa, Takashi; Shih, Chunghao Phillip; Leonard, Keith J.; Snead, Lance Lewis; Katoh, Yutai

    2014-07-01

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

  5. Peer Victimisation and Its Relationships with Perceptions of Body Composition

    ERIC Educational Resources Information Center

    Frisen, Ann; Lunde, Carolina; Hwang, Philip

    2009-01-01

    The present study examined the links between children's exposure to peer victimisation, in terms of type and frequency, their body composition and subjective perceptions of body composition. A total of 960 Swedish 10-year-olds (515 girls and 445 boys) completed questionnaires about their peer victimisation experiences, weight and height, and…

  6. The Body Composition of a College Football Team.

    ERIC Educational Resources Information Center

    Wickkiser, John D.; Kelly, John M.

    This study focuses on the body composition and anthropometric measurements of 65 college football players. Body composition was determined by underwater weighing with an accurate assessment of residual volume. The anthropometric measurements included height, weight, seven skinfolds, waist circumference, and wrist diameter. A step-wise multiple…

  7. Body composition and dietary intake in neoplasic disease

    SciTech Connect

    Cohn, S.H.; Gartenhaus, W.; Vartsky, D.; Sawitsky, A.; Zanzi, I.; Vaswani, A. Yasummure, S.; Rai, K.; Cartes, E.; Ellis, K.J.

    1981-10-01

    Changes in body composition in 37 cancer patients were studied over a period of 6 months. Initially, the patients were divided into two groups: those who lost body weight (over 10%) and those who maintained or gained body weight before the study. Analysis of body composition indicated that patients who lost body weight has caloric and protein intakes markedly below ''normal'' levels at the beginning of the study. There also appears to be a direct relationship between the protein intake and the total body potassium/total body water ratio in the cancer patients. At the end of the 6-month study, the patients were again placed into two groups on the basis of weight loss or gain (and maintenance). Changes in body composition over the period were analyzed in terms of lean body mass, its protein constituent, water, and fat. Weight loss was found to reflect primarily the loss of fat, water, lean body mass (potassium), and only to a minor extent the protein component of lean body mass (nitrogen). Further, on the basis of the values of the ratios of total body nitrogen/total body potassium/total body water, it was possible to ascertain the relative normalcy of the body tissue gained or lost in the 6-month period. The results of the study suggest that the ratio total body nitrogen/total body potassium may serve as the best indicator of recent or ongoing catabolism or anabolism of the neoplastic process. By means of the application of the techniques used for the determination of body composition, it should be possible to assess regimes of hyperalimentation of cancer patients who lose body weight. (JMT)

  8. Body Composition Measurements of 161-km Ultramarathon Participants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study compares body composition characteristics with performance among participants in a 161-km trail ultramarathon. Height, mass, and percent body fat from bioimpedence spectroscopy were measured on 72 starters. Correlation analyses were used to compare body characteristics with finish time, ...

  9. Effect of physical activity on body composition

    SciTech Connect

    Zanzi, I; Ellis, K J; Aloia, J; Cohn, S H

    1980-01-01

    It has been noted that the deleterious effects on bone calcium of prolonged periods of inactivity, such as bed rest, are halted following resumption of activity. It would seem possible in light of the observations that have been made, that exercise may stimulate bone formation and perhaps counter, to some extent, bone loss as observed in the osteoporosis of aging. The present study was designed to determine the relation between total body calcium, total body potassium and bone mineral content of the radius to the degree of physical activity in a population of normal subjects. Measurement of the calcium was made by in-vivo total body neutron activation analysis. Bone mineral content of the radius and total body potassium, (an index of lean body mass) were measured by photon absorptiometry and the whole body counter, respectively.

  10. Study of multi-carbide B4C-SiC/(Al, Si) reaction infiltrated composites by SEM with EBSD

    NASA Astrophysics Data System (ADS)

    Almeida, B. A.; Ferro, M. C.; Ravanan, A.; Grave, P. M. F.; Wu, H.-Y.; Gao, M.-X.; Pan, Y.; Oliveira, F. J.; Lopes, A. B.; Vieira, J. M.

    2014-03-01

    In the definition of conceptual developments and design of new materials with singular or unique properties, characterisation takes a key role in clarifying the relationships of composition, properties and processing that define the new material. B4C has a rare combination of properties that makes it suitable for a wide range of applications in engineering: high refractoriness, thermal stability, high hardness and abrasion resistance coupled to low density. However, the low self-diffusion coefficient of B4C limits full densification by sintering. A way to overturn this constraint is by using an alloy, for example Al-Si, forming composites with B4C. Multi-carbide B4C-SiC/(Al, Si) composites were produced by the reactive melt infiltration technique at 1200 - 1350 °C with up to 1 hour of isothermal temperature holds. Pressed preforms made from C-containing B4C were spontaneously infiltrated with Al-Si alloys of composition varying from 25 to 50 wt% Si. The present study involves the characterisation of the microstructure and crystalline phases in the alloys and in the composites by X-ray diffraction and SEM/EDS with EBSD. Electron backscatter diffraction is used in detail to look for segregation and spatial distribution of Si and Al containing phases during solidification of the metallic infiltrate inside the channels of the ceramic matrix when the composite cools down to the eutectic temperature (577 °C). It complements elemental maps of the SEM/EDS. The production of a flat surface by polishing is intrinsically difficult and the problems inherent to the preparation of EBSD qualified finishing in polished samples of such type of composites are further discussed.

  11. Body composition of piglets exhibiting different growth rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The growth and composition of the neonatal pig is of interest because of potential impact on subsequent growth and finally, composition at market weight. The purpose of this study was to compare at weaning the growth and body composition of the largest and smallest pigs (excluding runts) from each o...

  12. Body composition in ileostomy patients with and without ileal resection.

    PubMed Central

    Cooper, J C; Laughland, A; Gunning, E J; Burkinshaw, L; Williams, N S

    1986-01-01

    Body composition was measured in 24 patients who had previously undergone proctocolectomy and ileostomy. One group (control group) had undergone resection of only small amounts of terminal ileum (median 4 cm), the other group of patients (resected group) had undergone resection of greater lengths of small bowel (median 54 cm). These values of body composition were then compared with predicted values in normal subjects. Proctocolectomy and ileostomy without ileal resection did not significantly affect body weight, or the body contents of fat or water, but led to a reduction in total body nitrogen and total body potassium, suggesting a reduction in fat free mass. A modest resection of the terminal ileum undertaken during the course of proctocolectomy decreased body weight largely because of a reduction in body fat. None of the ileostomy patients was found to be dehydrated. PMID:3721291

  13. Compositional effects on mechanical properties of hafnium-carbide-strengthened molybdenum alloys

    NASA Technical Reports Server (NTRS)

    Witzke, W. R.

    1975-01-01

    The mechanical properties of swaged rod thermomechanically processed from arc melted Mo-2Re-Hf-C alloys containing as much as 0.9-mol% HfC were evaluated. The low-temperature ductilities of these alloys were not influenced by the amount of HfC present but by the amount of Hf in excess of stoichiometry. Maximum ductility occurred at 0.2- to 0.3-at.% excess Hf. At 0.3- to 0.5-mol% HfC, alloy strength varied directly with the Mo content of extracted carbide particles, both decreasing as the amount of excess Hf increased. Additions of 2-at.% Re had little effect on strength or ductility. Tensile and creep strengths of Mo-2Re-0.7Hf-0.5C alloy equaled or exceeded those of other high strength Mo alloys.

  14. Hertzian indentation of colloidally processed titanium carbide-nickel aluminide composites

    NASA Astrophysics Data System (ADS)

    Collier, R. Bradley

    Advanced cermets based on titanium carbide (TiC), with a ductile nickel aluminide (Ni3Al) binder, have shown significant promise for use in a variety of demanding wear environments, due to a combination of high strength and good corrosion behaviour. A unique feature of TiC-Ni3Al cermets is that they show increasing strength from room temperature up to ˜1,000°C, while current materials such as tungsten carbide/cobalt (WC/Co) show significant strength degradation above ˜500°C. In this thesis, aqueous colloidal forming methods have been applied to process TiC preforms. The mechanisms and effectiveness of suspension stabilization were examined using methods such as zeta potential analysis, rheological measurements, and sedimentation trials for two common dispersants; an ammonium salt of polymethacrylate (PMA-NH 4) and two molecular weights (l,800 and 10,000) of polyethylenimine (PEI). TiC preforms were prepared by slip casting suspensions of up to 50 vol. % solids content. After drying, the TiC-based cermets were processed by melt infiltration with the Ni3Al alloy (IC-50) at 1475°C.Ni 3Al content was varied between 20 and 50 vol. % using this approach, resulting in final densities that exceeded 98% of theoretical. These samples were subjected to Hertzian indentation testing with loads ranging from 250 -- 2000 N, using WC-Co spheres with sizes ranging from 1.191 to 2.38 mm. Indentation stress-strain curves were produced from the indentation data and compared to the calculated elastic Hertzian response. The bonded interface method was used to examine the subsurface deformation of the material under load. Significant deformation of the binder and the eventual fracture of the TiC grains were observed. The nature of the quasi-plasticity of TiC-Ni 3Al and the effects of binder content on surface and subsurface deformation is examined.

  15. Body composition changes in pregnancy: measurement, predictors and outcomes

    PubMed Central

    Widen, EM; Gallagher, D

    2014-01-01

    Prevalence of overweight and obesity has risen in the United States over the past few decades. Concurrent with this rise in obesity has been an increase in pregravid body mass index and gestational weight gain affecting maternal body composition changes in pregnancy. During pregnancy, many of the assumptions inherent in body composition estimation are violated, particularly the hydration of fat-free mass, and available methods are unable to disentangle maternal composition from fetus and supporting tissues; therefore, estimates of maternal body composition during pregnancy are prone to error. Here we review commonly used and available methods for assessing body composition changes in pregnancy, including: (1) anthropometry, (2) total body water, (3) densitometry, (4) imaging, (5) dual-energy X-ray absorptiometry, (6) bioelectrical impedance and (7) ultrasound. Several of these methods can measure regional changes in adipose tissue; however, most of these methods provide only whole-body estimates of fat and fat-free mass. Consideration is given to factors that may influence changes in maternal body composition, as well as long-term maternal and offspring outcomes. Finally, we provide recommendations for future research in this area. PMID:24667754

  16. Methods for Producing High-Performance Silicon Carbide Fibers, Architectural Preforms, and High-Temperature Composite Structures

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A. (Inventor); Yun, Hee-Mann (Inventor)

    2014-01-01

    Methods are disclosed for producing architectural preforms and high-temperature composite structures containing high-strength ceramic fibers with reduced preforming stresses within each fiber, with an in-situ grown coating on each fiber surface, with reduced boron within the bulk of each fiber, and with improved tensile creep and rupture resistance properties tier each fiber. The methods include the steps of preparing an original sample of a preform formed from a pre-selected high-strength silicon carbide ceramic fiber type, placing the original sample in a processing furnace under a pre-selected preforming stress state and thermally treating the sample in the processing furnace at a pre-selected processing temperature and hold time in a processing gas having a pre-selected composition, pressure, and flow rate. For the high-temperature composite structures, the method includes additional steps of depositing a thin interphase coating on the surface of each fiber and forming a ceramic or carbon-based matrix within the sample.

  17. Tungsten carbide/porous carbon composite as superior support for platinum catalyst toward methanol electro-oxidation

    SciTech Connect

    Jiang, Liming; Fu, Honggang; Wang, Lei; Mu, Guang; Jiang, Baojiang; Zhou, Wei; Wang, Ruihong

    2014-01-01

    Graphical abstract: The WC nanoparticles are well dispersed in the carbon matrix. The size of WC nanoparticles is about 30 nm. It can be concluded that tungsten carbide and carbon composite was successfully prepared by the present synthesis conditions. - Highlights: • The WC/PC composite with high specific surface area was prepared by a simple way. • The Pt/WC/PC catalyst has superior performance toward methanol electro-oxidation. • The current density for methanol electro-oxidation is as high as 595.93 A g{sup −1} Pt. • The Pt/WC/PC catalyst shows better durability and stronger CO electro-oxidation. • The performance of Pt/WC/PC is superior to the commercial Pt/C (JM) catalyst. - Abstract: Tungsten carbide/porous carbon (WC/PC) composites have been successfully synthesized through a surfactant assisted evaporation-induced-assembly method, followed by a thermal treatment process. In particular, WC/PC-35-1000 composite with tungsten content of 35% synthesized at the carbonized temperature of 1000 °C, exhibited a specific surface area (S{sub BET}) of 457.92 m{sup 2} g{sup −1}. After loading Pt nanoparticles (NPs), the obtained Pt/WC/PC-35-1000 catalyst exhibits the highest unit mass electroactivity (595.93 A g{sup −1} Pt) toward methanol electro-oxidation, which is about 2.6 times as that of the commercial Pt/C (JM) catalyst. Furthermore, the Pt/WC/PC-35-1000 catalyst displays much stronger resistance to CO poisoning and better durability toward methanol electrooxidation compared with the commercial Pt/C (JM) catalyst. The high electrocatalytic activity, strong poison-resistivity and good stability of Pt/WC/PC-35-1000 catalyst are attributed to the porous structures and high specific surface area of WC/PC support could facilitate the rapid mass transportation. Moreover, synergistic effect between WC and Pt NPs is favorable to the higher catalytic performance.

  18. Non-invasive techniques for determining musculoskeleton body composition

    SciTech Connect

    Cohn, S.H.

    1984-01-01

    In vivo neutron activation analysis, combined with gamma spectrometry, has ushered in a new era of clinical diagnosis and evaluation of therapies, as well as investigation into and modelling of body composition in both normal individuals and patients suffering from various diseases and dysfunctions. Body composition studies have provided baseline data on such vital constituents as nitrogen, potassium and calcium. The non-invasive measurement techniques are particularly suitable for study of the musculo-skeletal changes in body composition. Of particular relevance here is the measurement of calcium loss in astronauts during prolonged space flights.

  19. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.

    2016-09-01

    CM chondrites are the most common type of hydrated meteorites, making up ˜1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (˜0°C–120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (<300°C) thermal evolution of the CM parent body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D < 10 km) in the early solar system.

  20. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.

    2016-09-01

    CM chondrites are the most common type of hydrated meteorites, making up ˜1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (˜0°C-120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (<300°C) thermal evolution of the CM parent body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D < 10 km) in the early solar system.

  1. Association between Human Body Composition and Periodontal Disease.

    PubMed

    Salekzamani, Yagoub; Shirmohammadi, Adileh; Rahbar, Mohammad; Shakouri, Seyed-Kazem; Nayebi, Farough

    2011-01-01

    Obesity in humans might increase the risk of periodontitis. The aim of the present study was to examine the relationship between body composition of males and their periodontal status. AS total of 150 males (aged 30-60) were selected: 31 were periodontally healthy, 45 had gingivitis, 39 had initial periodontitis, and 35 suffered from established periodontitis. BMI (body mass index), WC (waist circumference), and body composition parameters (consisting of body water, body fat, and skeletal muscle and bone mass) were measured. After adjusting for age, history of diabetes, smoking, physical activity status, and socioeconomic status, statistically significant correlations were found between periodontitis and BMI, WC, and body composition. There was only a statistically significant difference between the periodontal health and established periodontitis; that is, periodontal disease in mild forms (gingivitis) and initial periodontitis do not influence these variables (BMI, WC, and body composition parameters) and only the severe form of the disease influences the variables. These data suggest that there is a considerable association between severe forms of periodontal disease in males and their body composition, but this preliminary finding needs to be confirmed in more extensive studies. PMID:22111011

  2. High Dose Neutron Irradiation of Hi-Nicalon Type S Silicon Carbide Composites, Part 2. Mechanical and Physical Properties

    DOE PAGESBeta

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao Phillip; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wallace D; Snead, Lance Lewis

    2015-01-07

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573–1073 K. Likewise, the material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating themore » irradiation temperature, but only to a limited extent. Moreover, the observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.« less

  3. Titania Composites with 2 D Transition Metal Carbides as Photocatalysts for Hydrogen Production under Visible-Light Irradiation

    DOE PAGESBeta

    Wang, Hui; Peng, Rui; Hood, Zachary D.; Naguib, Michael; Adhikari, Shiba P.; Wu, Zili

    2016-05-24

    In the MXenes family of two-dimensional transition-metal carbides there were successful demonstrations of co-catalysts with rutile TiO2 for visible-light-induced solar hydrogen production from water splitting. The physicochemical properties of Ti3C2Tx MXene coupled with TiO2 were investigated by a variety of characterization techniques. The effect of the Ti3C2Tx loading on the photocatalytic performance of the TiO2/Ti3C2Tx composites was elucidated. Moreover, with an optimized Ti3C2Tx content of 5 wt %, the TiO2/Ti3C2Tx composite shows a 400 % enhancement in the photocatalytic hydrogen evolution reaction compared with that of pure rutile TiO2. We also expanded our exploration to other MXenes (Nb2CTx and Ti2CTx)more » as co-catalysts coupled with TiO2, and these materials also exhibited enhanced hydrogen production. These results manifest the generality of MXenes as effective co-catalysts for solar hydrogen production.« less

  4. Titania Composites with 2 D Transition Metal Carbides as Photocatalysts for Hydrogen Production under Visible-Light Irradiation.

    PubMed

    Wang, Hui; Peng, Rui; Hood, Zachary D; Naguib, Michael; Adhikari, Shiba P; Wu, Zili

    2016-06-22

    MXenes, a family of two-dimensional transition-metal carbides, were successfully demonstrated as co-catalysts with rutile TiO2 for visible-light-induced solar hydrogen production from water splitting. The physicochemical properties of Ti3 C2 Tx MXene coupled with TiO2 were investigated by a variety of characterization techniques. The effect of the Ti3 C2 Tx loading on the photocatalytic performance of the TiO2 /Ti3 C2 Tx composites was elucidated. With an optimized Ti3 C2 Tx content of 5 wt %, the TiO2 /Ti3 C2 Tx composite shows a 400 % enhancement in the photocatalytic hydrogen evolution reaction compared with that of pure rutile TiO2 . We also expanded our exploration to other MXenes (Nb2 CTx and Ti2 CTx ) as co-catalysts coupled with TiO2 , and these materials also exhibited enhanced hydrogen production. These results manifest the generality of MXenes as effective co-catalysts for solar hydrogen production. PMID:27219205

  5. Intermediate-temperature environmental effects on boron nitride-coated silicon carbide-fiber-reinforced glass-ceramic composites

    SciTech Connect

    Sun, E.Y.; Lin, H.T.; Brennan, J.J.

    1997-03-01

    The environmental effects on the mechanical properties of fiber-reinforced composites at intermediate temperatures were investigated by conducting flexural static-fatigue experiments in air at 600 and 950 C. The material that was studied was a silicon carbide/boron nitride (SiC/BN) dual-coated Nicalon-fiber-reinforced barium magnesium aluminosilicate glass-ceramic. Comparable time-dependent failure responses were found at 600 and 950 C when the maximum tensile stress applied in the bend bar was >60% of the room-temperature ultimate flexural strength of as-received materials. At both temperatures, the materials survived 500 h fatigue tests at lower stress levels. Among the samples that survived the 500 h fatigue tests, a 20% degradation in the room temperature flexural strength was measured in samples that were fatigued at 600 C. The growth rate of the Si-C-O fiber oxidation product at 600 C was not sufficient to seal the stress-induced cracks, so that the interior of the material was oxidized and resulted in a strength degradation and less fibrous fracture. In contrast, the interior of the material remained intact at 950 C because of crack sealing by rapid silicate formation, and strength/toughness of the composite was maintained. Also, at 600 C, BN oxidized via volatilization, because no borosilicate was formed.

  6. Bioelectrical Impedance and Body Composition Assessment

    ERIC Educational Resources Information Center

    Martino, Mike

    2006-01-01

    This article discusses field tests that can be used in physical education programs. The most common field tests are anthropometric measurements, which include body mass index (BMI), girth measurements, and skinfold testing. Another field test that is gaining popularity is bioelectrical impedance analysis (BIA). Each method has particular strengths…

  7. Ultrafine Molybdenum Carbide Nanoparticles Composited with Carbon as a Highly Active Hydrogen-Evolution Electrocatalyst.

    PubMed

    Ma, Ruguang; Zhou, Yao; Chen, Yongfang; Li, Pengxi; Liu, Qian; Wang, Jiacheng

    2015-12-01

    The replacement of platinum with non-precious-metal electrocatalysts with high efficiency and superior stability for the hydrogen-evolution reaction (HER) remains a great challenge. Herein, we report the one-step synthesis of uniform, ultrafine molybdenum carbide (Mo2C) nanoparticles (NPs) within a carbon matrix from inexpensive starting materials (dicyanamide and ammonium molybdate). The optimized catalyst consisting of Mo2C NPs with sizes lower than 3 nm encapsulated by ultrathin graphene shells (ca. 1-3 layers) showed superior HER activity in acidic media, with a very low onset potential of -6 mV, a small Tafel slope of 41 mV dec(-1), and a large exchange current density of 0.179 mA cm(-2), as well as good stability during operation for 12 h. These excellent properties are similar to those of state-of-the-art 20% Pt/C and make the catalyst one of the most active acid-stable electrocatalysts ever reported for HER.

  8. Body Composition Assessment--Some Practical Answers to Teachers' Questions.

    ERIC Educational Resources Information Center

    Thomas, David Q.; Whitehead, James R.

    1993-01-01

    Presents information about body composition assessment, including how useful the measurement is, how to conduct assessment, accurate skinfold measurement, body mass index versus skinfold results, interpreting results, standards for score interpretation, other types of measurement, how to approach skinfold assessment, and handling sensitivity and…

  9. In vivo measurement of human body composition

    NASA Technical Reports Server (NTRS)

    Pace, N.; Grunbaum, B. W.; Kodama, A. M.; Price, D. C.

    1974-01-01

    The female bed rest study has shown that, the response of women to prolonged recumbency of 2 to 3 weeks duration is very similar to that displayed by men. Some of the key findings in the women after 17 days of continuous recumbency are: (1) a decrease in plasma volume of 12-13 per cent; (2) a small decrease in total body water; (3) a decrease in total body potassium of 3 to 4 per cent; (4) a decrease in plasma potassium concentration of 4 to 5 per cent; (5) a decrease in total circulating plasma protein of 11 to 12 per cent; (6) a decrease in urinary norepinephrine excretion rate of 27 to 28 per cent; (7) a possible increase in urinary magnesium, calcium, and phosphate excretion rates; and (8) a possible increase in urinary citrate excretion rate.

  10. Body composition of elite American athletes.

    PubMed

    Fleck, S J

    1983-01-01

    Five hundred twenty-eight male athletes participating in 26 Olympic events and 298 female athletes participating in 15 Olympic events underwent determination of body fat percentage (% fat) and lean body mass (LBM) via hydrostatic weighing and/or anthropometric methods. All groups of athletes were below the average values for % fat of college age men and women of 15% and 25%, respectively. In general, athletes involved in a sport where their body weight is supported, such as canoe and kayak (males, 13.0 +/- 2.5%; females, 22.2 +/- 4.6%) and swimming (males, 12.4 +/- 3.7%; females 19.5 +/- 2.8%), tended to have higher % fat values. Athletes involved in sports where a weight class has to be made to compete, such as boxing (males, 6.9 +/- 1.6%) and wrestling (male, Junior World Freestyle 7.9 +/- 2.7%), events such as the 100, 200, and 400 meters in athletes (male 100 and 200 meters, 6.5 +/- 1.2%; female 100, 200 and 400 meters, 13.7 +/- 3.6%) that are very anaerobic in nature and extremely aerobic events such as the marathon (males, 6.4 +/- 1.3%) demonstrated lower % fat values. Athletes involved in sports where body size is a definite advantage, such as basketball (males, 84.1 +/- 6.2 kg; females, 55.3 +/- 4.9 kg) and volleyball (males, 75.0 +/- 6.6 kg; females, 58.4 +/- 4.5 kg) tended to have a larger LBM.

  11. Relationships Between Body Image, Body Composition, Sexual Functioning, and Sexual Satisfaction Among Heterosexual Young Adults.

    PubMed

    Milhausen, Robin R; Buchholz, Andrea C; Opperman, Emily A; Benson, Lindsay E

    2015-08-01

    This study investigated the association between body image and body-image self-consciousness on sexual satisfaction, accounting for relationships between body fat and body image, and between sexual functioning and sexual satisfaction, while controlling for relationship satisfaction. Participants were 143, 18-25 year-old Caucasian men and women in heterosexual monogamous relationships, recruited from the University of Guelph and surrounding community in Ontario, Canada. Various domains of body image, body-image self-consciousness, sexual satisfaction and functioning, and relationship satisfaction data were collected by questionnaires. Body fat was measured using dual energy X-ray absorptiometry. Among men, body image was positively associated with sexual satisfaction, after controlling for relationship satisfaction. Men with greater body fat were more likely to have poorer behavioral and affective body image. Only body image specific to the sexual encounter influenced sexual functioning. Among women, no domain of body image was associated with sexual satisfaction, after controlling for relationship satisfaction. Women with greater body fat were more likely to have poorer affective and sexual-encounter-specific body image. As percent total fat increased, sexual functioning decreased. Our results suggest a complex pattern of relationships exists among body image and body composition constructs and sexual and relationship variable; and that these relationships are not the same for men and women.

  12. Application of standards and models in body composition analysis.

    PubMed

    Müller, Manfred J; Braun, Wiebke; Pourhassan, Maryam; Geisler, Corinna; Bosy-Westphal, Anja

    2016-05-01

    The aim of this review is to extend present concepts of body composition and to integrate it into physiology. In vivo body composition analysis (BCA) has a sound theoretical and methodological basis. Present methods used for BCA are reliable and valid. Individual data on body components, organs and tissues are included into different models, e.g. a 2-, 3-, 4- or multi-component model. Today the so-called 4-compartment model as well as whole body MRI (or computed tomography) scans are considered as gold standards of BCA. In practice the use of the appropriate method depends on the question of interest and the accuracy needed to address it. Body composition data are descriptive and used for normative analyses (e.g. generating normal values, centiles and cut offs). Advanced models of BCA go beyond description and normative approaches. The concept of functional body composition (FBC) takes into account the relationships between individual body components, organs and tissues and related metabolic and physical functions. FBC can be further extended to the model of healthy body composition (HBC) based on horizontal (i.e. structural) and vertical (e.g. metabolism and its neuroendocrine control) relationships between individual components as well as between component and body functions using mathematical modelling with a hierarchical multi-level multi-scale approach at the software level. HBC integrates into whole body systems of cardiovascular, respiratory, hepatic and renal functions. To conclude BCA is a prerequisite for detailed phenotyping of individuals providing a sound basis for in depth biomedical research and clinical decision making.

  13. Effect of intense military training on body composition.

    PubMed

    Malavolti, Marcella; Battistini, Nino C; Dugoni, Manfredo; Bagni, Bruno; Bagni, Ilaria; Pietrobelli, Angelo

    2008-03-01

    Individuals in a structural physical training program can show beneficial changes in body composition, such as body fat reduction and muscle mass increase. This study measured body composition changes by using 3 different techniques-skinfold thickness (SF) measurements, air displacement plethysmography (BOD-POD), and dual-energy x-ray absorptiometry (DXA)-during 9 months of intense training in healthy young men engaged in military training. Twenty-seven young men were recruited from a special faction of the Italian Navy. The program previewed three phases: ground combat, sea combat, and amphibious combat. Body composition was estimated at the beginning, in the middle, and at the end of the training. After the subjects performed the ground combat phase, body composition variables significantly decreased: body weight (P < 0.05), fat-free mass (FFM) (P < 0.001), and fat mass (FM) (P < 0.03). During the amphibious combat phase, body weight increased significantly (P < 0.01), mainly because of an increase in FFM (P < 0.001) and a smaller mean decrease in FM. There was a significant difference (P < 0.05) in circumferences and SF at various sites after starting the training course. Bland-Altman analysis did not show any systematic difference between FM and FFM measured with the 3 different techniques on any occasion. On any visit, FFM and FM correlation measured by BOD-POD (P = 0.90) and DXA was significantly greater than measured by SF. A significant difference was found in body mass index (BMI) measured during the study. BOD-POD and SF, compared with DXA, provide valid and reliable measurement of changes in body composition in healthy young men engaged in military training. In conclusion, the findings suggest that for young men of normal weight, changes in body weight alone and in BMI are not a good measure to assess the effectiveness of intense physical training programs, because lean mass gain can masquerade fat weight loss.

  14. Using the Acoustic Emission Technique for Estimating Body Composition

    NASA Astrophysics Data System (ADS)

    González-Solís, J. L.; Sanchis-Sabater, A.; Sosa-Aquino, M.; Gutiérrez-Juárez, G.; Vargas-Luna, M.; Bernal-Alvarado, J.; Huerta-Franco, R.

    2003-09-01

    This work proposes a new technique for estimation of body composition by using acoustic emission. A simple apparatus for the acoustic emission is proposed.The estimation of the body composition is made by analyzing the correlation between a set of acoustic resonance and skinfold measurements. One device was designed to measure the position and width of the acoustic resonances and a caliper was used to measure the skinfolds. The results show the plausibility of application of the method to measurement the human body fat.

  15. The influence of body composition on youth throwing kinetics.

    PubMed

    Garner, John C; MacDonald, Chris; Wade, Chip; Johnson, Andrea; Ford, M Allison

    2011-08-01

    The primary objective of this study was to investigate the influence of segmental mass and body composition on the upper extremity biomechanics of overweight youth participating in baseball activities. The study used a regression framework to investigate the relationship between whole body, throwing arm segmental mass and body composition measures to kinetic variables about the shoulder and elbow. The multivariate regression results indicated a strong positive significant relationship between each of the mass variables to that of the moment variables about the shoulder and elbow. Participants who had a greater percentage of fat mass produced greater injury correlated moments about the shoulder and elbow.

  16. [Body composition in amenorrheic and eumenorrheic underweight patients].

    PubMed

    Mocanu, V; Colev, V; Vulpoi, C; Stoica, A R; Mironovici, D; Railean, R; Zbranca, E

    2000-01-01

    Relationship between weight and hypothalamic-pituitary-ovarian axis has been long time studied. Underweight female patients can have or not disturbances of gonadal system and the importance of the weight or body composition in the mechanisms of these abnormalities is not clear. In our study, we have investigated body composition in 15 underweight female patients. Five patients have had anorexia nervosa, with amenorrhea (group AN), and other 10 patients were eumenorrheic, but with low body weight (hypoanabolic syndrome--group HA). Bioelectrical impedance method was used to investigate body composition. Total body water (TBW), lean mass (LM), and fat mass (FM) were determined. Nutritional status was also assessed using body mass index (BMI). The mean body weight was significantly decreased (p = 0.05, 36.6 +/- 4.68 Kg versus 44.1 +/- 4.67 Kg) in group AN as compared to group HA. Fat mass was very low in group AN (9.45% of body weight versus 11.3% of body weight in group HA), but there was not significant difference. Lean mass was significantly decreased in group AN (33.24 +/- 2.37 Kg) in comparison with group HA (39.3 +/- 4.06 Kg). Correlations between anthropometric indices were studied. Positive significant correlations were obtained between body weight and lean mass, total body water and basal metabolism in both groups. In conclusion, our study reveals that body weight has a relative importance in ovarian axis dysfunction, and the most important of body compartments seems to be lean mass.

  17. Materials characterization of silicon carbide reinforced titanium (Ti/SCS-6) metal matrix composites. Part 1: Tensile and fatigue behavior

    SciTech Connect

    Liaw, P.K.; Diaz, E.S.; Chiang, K.T.; Loh, D.H.

    1995-12-01

    Flexural fatigue behavior was investigated on titanium (Ti-15V-3Cr) metal matrix composites reinforced with cross-ply, continuous silicon carbide (SiC) fibers. The titanium composites had an eight-ply (0, 90, +45, {minus}45 deg) symmetric layup. Fatigue life was found to be sensitive to fiber layup sequence. Increasing the test temperature from 24 C to 427 C decreased fatigue life. Interface debonding and matrix and fiber fracture were characteristic of tensile behavior regardless of test temperature. In the tensile fracture process, interface debonding between SiC and the graphite coating and between the graphite coating and the carbon core could occur. A greater amount of coating degradation at 427 C than at 24 C reduced the Ti/SiC interface bonding integrity, which resulted in lower tensile properties at 427 C. During tensile testing, a crack could initiate from the debonded Ti/SiC interface and extend to the debonded interface of the neighboring fiber. The crack tended to propagate through the matrix and the interface. Dimpled fracture was the prime mode of matrix fracture. Interface debonding, matrix cracking, and fiber bridging were identified as the prime modes of fatigue mechanisms. To a lesser extent, fiber fracture was observed during fatigue. However, fiber fracture was believed to occur near the final stage of fatigue failure. In fatigued specimens, facet-type fracture appearance was characteristic of matrix fracture morphology. Theoretical modeling of the fatigue behavior of Ti/SCS-6 composites is presented in Part 2 of this series of articles.

  18. Formation of carbon nanotubes from a silicon carbide/carbon composite

    NASA Astrophysics Data System (ADS)

    Joshi, Ravi; Engstler, Jörg; Haridoss, Prathap; Schneider, Jörg J.

    2009-02-01

    The reaction of a SiC/C composite powder in an arcing plasma forms carbon nanotubes in good yield. Besides carbon nanotubes, a Si/C composite composed of β SiC covered with a shell of graphite is formed. The graphitic carbon surface layers of the carbon shell of this composite reacts further to form carbon nanotubes when heated to 600 °C. This process seems highly effective since only a small overall low weight loss, indicative for a complete carbon shell oxidation is observed by thermal analysis. The formation of the carbon nanotubes from SiC is unlikely since no SiO 2 has been found when heating the SiC/C core shell composite to its reaction temperature of 600 °C under O 2. The CNTs formed are of good quality with 3 to 6 concentric walls and high aspect ratio. Occasionally even single walled carbon naotubes have been observed.

  19. New composite composed of boron carbide and carbon fiber with high thermal conductivity for first wall

    NASA Astrophysics Data System (ADS)

    Jimbou, R.; Saidoh, M.; Nakamura, K.; Akiba, M.; Suzuki, S.; Gotoh, Y.; Suzuki, Y.; Chiba, A.; Yamaki, T.; Nakagawa, M.; Morita, K.; Tsuchiya, B.

    1996-10-01

    A new composite was created from B 4C powder and carbon fiber by hot-pressing at 1700°C or more. The composite sintered at 1700°C with 20-35 vol% B 4C shows a thermal conductivity of 250 W/m·K at 25°C which is slightly lower than the felt type C/C, but its value becomes higher than the C/C at temperatures above 400°C. The composite with 40 at% B shows more controllable recycling properties than B 4C. The erosion yield for the composite is about half the yield for graphite at 800 K. After electron beam irradiation in order to test heat resistance no cracks were detected up to 22-23 MW/m 2 leading to a surface temperature of 2500°C.

  20. A Revival of Waste: Atmospheric Pressure Nitrogen Plasma Jet Enhanced Jumbo Silicon/Silicon Carbide Composite in Lithium Ion Batteries.

    PubMed

    Chen, Bing-Hong; Chuang, Shang-I; Liu, Wei-Ren; Duh, Jenq-Gong

    2015-12-30

    In this study, a jumbo silicon/silicon carbide (Si/SiC) composite (JSC), a novel anode material source, was extracted from solar power industry cutting waste and used as a material for lithium-ion batteries (LIBs), instead of manufacturing the nanolized-Si. Unlike previous methods used for preventing volume expansion and solid electrolyte interphase (SEI), the approach proposed here simply entails applying surface modification to JSC-based electrodes by using nitrogen-atmospheric pressure plasma jet (N-APPJ) treatment process. Surface organic bonds were rearranged and N-doped compounds were formed on the electrodes through applying different plasma treatment durations, and the qualitative examinations of before/after plasma treatment were identified by X-ray photoelectron spectroscopy (XPS) and electron probe microanalyzer (EPMA). The surface modification resulted in the enhancement of electrochemical performance with stable capacity retention and high Coulombic efficiency. In addition, depth profile and scanning electron microscope (SEM) images were executed to determine the existence of Li-N matrix and how the nitrogen compounds change the surface conditions of the electrodes. The N-APPJ-induced rapid surface modification is a major breakthrough for processing recycled waste that can serve as anode materials for next-generation high-performance LIBs.

  1. Hard coating of ultrananocrystalline diamond/nonhydrogenated amorphous carbon composite films on cemented tungsten carbide by coaxial arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Naragino, Hiroshi; Egiza, Mohamed; Tominaga, Aki; Murasawa, Koki; Gonda, Hidenobu; Sakurai, Masatoshi; Yoshitake, Tsuyoshi

    2016-08-01

    Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite (UNCD/a-C) films were deposited on cemented carbide containing Co by coaxial arc plasma deposition. With decreasing substrate temperature, the hardness was enhanced accompanied by an enhancement in the sp3/(sp2 + sp3). Energy-dispersive X-ray and secondary ion mass spectrometry spectroscopic measurements exhibited that the diffusion of Co atoms from the substrates into the films hardly occurs. The film deposited at room temperature exhibited the maximum hardness of 51.3 GPa and Young's modulus of 520.2 GPa, which evidently indicates that graphitization induced by Co in the WC substrates, and thermal deformation from sp3 to sp2 bonding are suppressed. The hard UNCD/a-C films can be deposited at a thickness of approximately 3 μm, which is an order larger than that of comparably hard a-C films. The internal compressive stress of the 51.3-GPa film is 4.5 GPa, which is evidently smaller than that of comparably hard a-C films. This is a reason for the thick deposition. The presence of a large number of grain boundaries in the film, which is a structural specific to UNCD/a-C films, might play a role in releasing the internal stress of the films.

  2. Skeletal and body composition evaluation. Final report

    SciTech Connect

    Mazess, R.B.

    1983-03-01

    Research on radiation detectors for absorptiometry analysis of errors affecting single photon absorptiometry and development of instrumentation, analysis of errors affecting dual photon absorptiometry and development of instrumentation, comparison of skeletal measurements with other techniques, cooperation with NASA projects for skeletal evaluation in spaceflight (Experiment MO-78) and in laboratory studies with immobilized animals, studies of postmenopausal osteoporosis, organization of scientific meetings and workshops on absorptiometric measurement, and development of instrumentation for measurement of fluid shifts in the human body were performed. Instrumentation was developed that allows accurate and precise (2% error) measurements of mineral content in compact and trabecular bone and of the total skeleton. Instrumentation was also developed to measure fluid shifts in the extremities. Radiation exposure with those procedures is low (2-10 MREM). One hundred seventy three technical reports and one hundred and four published papers of studies from the University of Wisconsin Bone Mineral Lab are listed.

  3. Early childhood predictors of adult body composition.

    PubMed

    Druet, Céline; Ong, Ken K

    2008-06-01

    Intra-uterine life has been identified as a possible critical period for the development of obesity risk in both adults and children; others have highlighted the importance of growth and nutrition in the first few years. It is suggested that fetal growth, as assessed by birth weight, may programme lean body mass later in life. Children who are born small for gestational age also have a predisposition to accumulating fat mass, particularly intra-abdominal fat. It is not yet clear whether this predisposition is due to their prenatal growth restraint, their rapid postnatal catch-up growth or a combination of both. Recently, genetic and heritable factors have been shown to contribute to both rapid postnatal growth and childhood obesity risk in children and adults. Future studies should explore their timing of action and potential interactions with markers of antenatal growth restraint.

  4. Nanosilicon carbide/hydroxyapatite nanocomposites: structural, mechanical and in vitro cellular properties.

    PubMed

    Hesaraki, Saeed; Ebadzadeh, Touraj; Ahmadzadeh-Asl, Shaghayegh

    2010-07-01

    In this study, bioceramic nanocomposites were synthesized by sintering compacted bodies of hydroxyapatite (HA) mixed with 5 or 15 wt% nanosilicon carbide at 1,100 or 1,200 degrees C in a reducing atmosphere. Pure hydroxyapatite was also prepared for comparison. Phase compositions, structural and physical properties of the composites were studied using appropriate techniques. Some in vitro biological properties of the composites were also investigated by using newrat calvaria osteoblastic cells. X-ray diffraction analysis indicated that tricalcium phosphate (TCP) comprising negligible alpha-TCP and considerable beta-TCP were formed in composites during sintering meanwhile hydroxyapatite and silicon carbide (SiC) were also existed in the composition. Based on the results, that composite made of 5 wt% nanosilicon carbide exhibited higher bending strength, fracture toughness and bulk density than pure HA and composite with 15 wt% silicon carbide. The scanning electron microscopy coupled with energy dispersive X-ray analysis revealed that the addition of nanosilicon carbide suppressed the grain growth and yielded a feature of island-type clusters consisting of blistered calcium phosphate (HA and TCP) and SiC grains. Also, in this study, better proliferation rate and alkaline phosphatase activity were observed for the osteoblastic cells seeded on top of the composites compared to pure HA. Overall, the results indicated that the composite of 95 wt% hydroxyapatite and 5 wt% SiC exhibited better mechanical and biological properties than pure HA and further addition of SiC failed strength and toughness.

  5. Residual stresses in silicon carbide-zircon composites from thermal expansion measurements and fiber pushout tests

    SciTech Connect

    Reddy, S.K.; Kumar, S.; Singh, R.N. . Dept. of Materials Science and Engineering)

    1994-12-01

    Coefficients of thermal expansion (CTE) in the axial direction of two types of SiC fibers, monolithic zircon, monolithic SiC, and several SiC[sub f]-zircon composites were measured in the temperature range of 50 to 1,380 C. The measured CTE values of composites were compared with values predicted by the rule-of-mixtures approach, and a small difference in measured and calculated values was ascribed to the nature of interfacial bonding and assumptions implicit in the rule-of-mixture approach. Fiber pushout tests were performed on these composites and the residual stresses were extracted from the analysis of the load-displacement plots in terms of the shear-lag and progressive debonding models. The radial and axial residual stresses arising from the mismatch in CTE were calculated and compared with values obtained from the fiber pushout tests. The fiber pushout tests in general produced lower values of the residual stresses, but the residual stresses obtained using shear-lag analysis were in good agreement with the calculated values based on the CTE mismatch in composites with lower values of the interfacial shear stress. The influence of anisotropic fiber expansion in the radial and axial directions on the radial and axial residual stresses in composites were also examined.

  6. High thermal conductivity of graphite fiber silicon carbide composites for fusion reactor application

    NASA Astrophysics Data System (ADS)

    Snead, L. L.; Balden, M.; Causey, R. A.; Atsumi, H.

    2002-12-01

    The benefits of using CVI SiC/graphite fiber composites as low tritium retaining, high thermal conductivity composites for fusion applications are presented. Three-dimensional woven composites have been chemically vapor infiltrated with SiC and their thermophysical properties measured. One material used an intermediate grade graphite fiber in all directions (Amoco P55) while a second material used very high thermal conductive fiber (Amoco K-1100) in the high fiber density direction. The overall void was less than 20%. Strength as measured by four-point bending was comparable to those of SiC/SiC composite. The room temperature thermal conductivity in the high conductivity direction was impressive for both materials, with values >70 W/m K for the P-55 and >420 W/m K for the K-1100 variant. The thermal conductivity was measured as a function of temperature and exceeds the highest thermal conductivity of CVD SiC currently available at fusion relevant temperatures (>600 °C). Limited data on the irradiation-induced degradation in thermal conductivity is consistent with carbon fiber composite literature.

  7. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOEpatents

    Wei, George C.

    1985-01-01

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al.sub.2 O.sub.3, mullite, or B.sub.4 C. The mixtures which contain a homogeneous dispersion of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600.degree. to 1950.degree. C. with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m.sup.1/2 which represents as much as a two-fold increase over that of the matrix material.

  8. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOEpatents

    Wei, George C.

    1993-01-01

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al.sub.2 O.sub.3, mullite, or B.sub.4 C. The mixtures which contain a homogeneous disperson of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600.degree. to 1950.degree. C. with pressing times varying from about 0.075 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m.sup.1/2 which represents as much as a two-fold increase over that of the matrix material.

  9. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOEpatents

    Wei, George C.

    1989-01-24

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al.sub.2 O.sub.3, mullite, or B.sub.4 C. The mixtures which contain a homogeneous disperson of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600.degree. to 1950.degree. C. with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MP.am.sup.1/2 which represents as much as a two-fold increase over that of the matrix material.

  10. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOEpatents

    Wei, George C.

    1993-11-16

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al.sub.2 O.sub.3, mullite, or B.sub.4 C. The mixtures which contain a homogeneous disperson of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1600.degree. to 1950.degree. C. with pressing times varying from about 0.075 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness of up to about 9 MPa.m.sup.1/2 which represents as much as a two-fold increase over that of the matrix material.

  11. Silicon carbide whisker reinforced ceramic composites and method for making same

    DOEpatents

    Wei, G.C.

    1989-01-24

    The present invention is directed to the fabrication of ceramic composites which possess improved mechanical properties especially increased fracture toughness. In the formation of these ceramic composites, the single crystal SiC whiskers are mixed with fine ceramic powders of a ceramic material such as Al{sub 2}O{sub 3}, mullite, or B{sub 4}C. The mixtures which contain a homogeneous dispersion of the SiC whiskers are hot pressed at pressures in a range of about 28 to 70 MPa and temperatures in the range of about 1,600 to 1,950 C with pressing times varying from about 0.75 to 2.5 hours. The resulting ceramic composites show an increase in fracture toughness which represents as much as a two-fold increase over that of the matrix material.

  12. Properties of silicon carbide fiber-reinforced silicon nitride matrix composites

    NASA Technical Reports Server (NTRS)

    Bhatt, Ramakrishna T.

    1988-01-01

    The mechanical properties of NASA Lewis developed SiC/RBSN composites and their thermal and environmental stability havd been studied. The composites consist of nearly 30 vol pct of aligned 142 micron diameter chemically vapor-deposited SiC fibers in a relatively porous silicon nitride matrix. In the as-fabricated condition, the unidirectional and 2-D composites exhibited metal-like stress-strain behavior, graceful failure, and showed improved properties when compared with unreinforced matrix of comparable density. Furthermore, the measured room temperature tensile properties were relativley independent of tested volume and were unaffected by artifical notches normal to the loading direction or by thermal shocking from temperatures up to 800 C. The four-point bend strength data measured as a function of temperature to 1400 C in air showed that as-fabricated strength was maintained to 1200 C. At 1400 C, however, nearly 15 pct loss in strength was observed. Measurement of room temperature tensile strength after 100 hr exposure at temperatures to 1400 C in a nitrogen environment indicated no loss from the as-fabricated composite strength. On the other hand, after 100 hr exposure in flowing oxygen at 1200 and 1400 C, the composites showed approximately 40 pct loss from their as-fabricated ultimate tensile strength. Those exposed between 400 to 1200 C showed nearly 60 pct strength loss. Oxidation of the fiber/matrix interface as well as internal oxidation of the porous Si3N4 matrix are likely mechanisms for strength degradation. The excellent strength reproducibility, notch insensitivity, and high temperature strength of the composite makes it an ideal candidate for advanced heat engine applications provided coating or densification methods are developed to avoid internal oxidation attack.

  13. Method of producing a silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P. (Inventor)

    1995-01-01

    A SrO-Al2O3-2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  14. Silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam (Inventor)

    1992-01-01

    A SrO-Al2O3 - 2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  15. The effects and underlying mechanism of interferon therapy on body weight and body composition.

    PubMed

    Alam, Ibrar; Ullah, Niamat; Alam, Iftikhar; Ali, Ijaz

    2013-11-01

    Body weight changes in HCV patients on interferon therapy are well documented. However, the underlying mechanism involved in these changes is poorly understood and rarely reported. The main objectives of this review are to 1) discuss changes in body weight and other compartments of body composition, particularly, body fat, and 2) to discuss the underlying mechanism for these changes. The literature review suggests weight loss (12-29%) as a function of interferon therapy is common, affecting up to 90% of HCV patients. Whilst, loss in weight means proportionate loss in other body compartments (lean body mass and body fat, in particular) data on changes in segmented body composition are fragmentary. The possible mechanisms underlying weight loss or changes in other body composition have been reported and these include suppressed appetite due to induction of TNF by IFN, a decrease in serum leptin level, and importantly mitochondrial damage induced by the therapy. It is, therefore, suggested that close monitoring of chronic HCV patients receiving PEG-IFN and/or ribavirin for side effects of these drugs, particularly those related to weight loss, is vitally important from clinical point of view.

  16. Somatic maturation and body composition in female healthy adolescents with or without adjustment for body fat

    PubMed Central

    Miranda, Valter Paulo N.; de Faria, Franciane Rocha; de Faria, Eliane Rodrigues; Priore, Silvia Eloiza

    2014-01-01

    Objective: To evaluate the relationship between the stages of somatic maturation and body composition in eutrophic female adolescents with or without excessive body fat. Methods: Cross-sectional study of 118 female adolescents, from 14 to 19 years-old, in Viçosa, Minas Gerais, Southeast Brazil. The adolescents were divided in two groups: Group 1 (G1), eutrophic with adequate body fat percentage, and Group 2 (G2), eutrophic with high body fat percentage. The somatic maturation was assessed by the formula for estimating the Peak Height Velocity (PHV). Results: The PHV had higher average score in G1 adolescents compared to G2 (0.26 versus 0.05; p=0.032). There was an association between G1, G2 and the somatic maturation (p=0.049). The female adolescents before and during PHV presented higher values of fat body BMI (p=0.034) and percentage of central fat (p=0.039) compared to the adolescents after PHV. There was a correspondence between before PHV stage and the excess of body fat (α=0.751). Conclusions: There was an association between somatic maturation and body composition in eutrophic female adolescents. Length, BMI and fat percentage were different among the somatic maturation stages. It is relevant to evaluate the somatic maturation and the changes occurring in the body composition during adolescence in order to better evaluate and manage the nutritional status and the body fat excess. PMID:24676194

  17. The Body and the Beautiful: Health, Attractiveness and Body Composition in Men’s and Women’s Bodies

    PubMed Central

    Brierley, Mary-Ellen; Brooks, Kevin R.; Mond, Jonathan; Stevenson, Richard J.

    2016-01-01

    The dominant evolutionary theory of physical attraction posits that attractiveness reflects physiological health, and attraction is a mechanism for identifying a healthy mate. Previous studies have found that perceptions of the healthiest body mass index (weight scaled for height; BMI) for women are close to healthy BMI guidelines, while the most attractive BMI is significantly lower, possibly pointing to an influence of sociocultural factors in determining attractive BMI. However, less is known about ideal body size for men. Further, research has not addressed the role of body fat and muscle, which have distinct relationships with health and are conflated in BMI, in determining perceived health and attractiveness. Here, we hypothesised that, if attractiveness reflects physiological health, the most attractive and healthy appearing body composition should be in line with physiologically healthy body composition. Thirty female and 33 male observers were instructed to manipulate 15 female and 15 male body images in terms of their fat and muscle to optimise perceived health and, separately, attractiveness. Observers were unaware that they were manipulating the muscle and fat content of bodies. The most attractive apparent fat mass for female bodies was significantly lower than the healthiest appearing fat mass (and was lower than the physiologically healthy range), with no significant difference for muscle mass. The optimal fat and muscle mass for men’s bodies was in line with the healthy range. Male observers preferred a significantly lower overall male body mass than did female observers. While the body fat and muscle associated with healthy and attractive appearance is broadly in line with physiologically healthy values, deviations from this pattern suggest that future research should examine a possible role for internalization of body ideals in influencing perceptions of attractive body composition, particularly in women. PMID:27257677

  18. Interfacial bonding and friction in silicon carbide (filament)-reinforced ceramic- and glass-matrix composites

    SciTech Connect

    Bright, J.D.; Shetty, D.K. . Dept. of Materials Science and Engineering); Griffin, C.W.; Limaye, S.Y. )

    1989-10-01

    This paper reports interfacial shear strength and interfacial sliding friction stress assessed in unidirectional SiC-filament-reinforced reaction-bonded silicon nitride (RBSN) and borosilicate glass composites and 0/90 cross-ply reinforced borosilicate glass composite using a fiber pushout test technique. The interface debonding load and the maximum sliding friction load were measured for varying lengths of the embedded fibers by continuously monitoring the load during debonding and pushout of single fibers in finite-thickness specimens. The dependences of the debonding load and the maximum sliding friction load on the initial embedded lengths of the fibers were in agreement with nonlinear shear-lag models. An iterative regression procedure was used to evaluate the interfacial properties, shear debond strength ({tau}{sub d}), and sliding friction stress ({tau}{sub f}), from the embedded fiber length dependences of the debonding load and the maximum frictional sliding load, respectively. The shear-lag model and the analysis of sliding friction permit explicit evaluation of a coefficient of sliding friction ({mu}) and a residual compressive stress on the interface ({sigma}{sub 0}). The cross-ply composite showed a significantly higher coefficient of interfacial friction as compared to the unidirectional composites.

  19. Developing scandium and zirconium containing aluminum boron carbide metal matrix composites for high temperature applications

    NASA Astrophysics Data System (ADS)

    Lai, Jing

    The study presented in this thesis focuses on developing castable, precipitation-strengthened Al--B4C metal matrix composites (MMCs) for high temperature applications. In the first part, B4C plates were immersed in liquid aluminum alloyed with Sc, Zr and Ti to investigate the interfacial reactions between B4C and liquid aluminum The influences of Sc, Zr and Ti on the interfacial microstructure in terms of individual and combined additions were examined. Results reveal that all three elements reacted with B4C and formed interfacial layers that acted as a diffusion barrier to limit the decomposition of B4C in liquid aluminum. The interfacial reactions and the reaction products in each system were identified. With the combined addition of Sc, Zr and Ti, most of the Ti was found to enrich at the interface, which not only offered appropriate protection of the B4C but also reduced the consumption of Sc and Zr at the interface. In the second part, Sc and Zr were introduced into Al-15vol.% B 4C composites presaturated by Ti, and eight experimental composites with different Sc and Zr levels were prepared via a conventional casting technique. It was found that Sc was involved in the interfacial reactions with B 4C that partially consume Sc. The Sc addition yielded considerable precipitation strengthening in the as-cast and peak aged conditions. To achieve an equivalent strengthening effect of Sc in binary Al-Sc alloys, approximately double the amount of Sc is required in Al-B4C composites. On the contrary, no major Zr reaction products were found at the interfaces and the major part of Zr remained in the matrix for the precipitation strengthening. The combination of Sc and Zr enhanced sthe precipitation strengthening. Two kinds of nanoscale precipitates, Al3Sc and Al3(Sc, Zr), were found in the as-cast microstructure and contributed to the increase in the matrix hardness. In the third part, all the experimental composites were isothermally aged at 300, 350, 400 and 450

  20. Damage evolution in uniaxial silicon carbide fiber-reinforced titanium matrix composites

    NASA Astrophysics Data System (ADS)

    Hanan, Jay Clarke

    Fiber fractures initiate damage zones ultimately determining the strength and lifetime of metal matrix composites (MMCs). The evolution of damage in a MMC comprising a row of unidirectional SiC fibers (32 vol.%) surrounded by a Ti matrix was examined using X-ray microdiffraction (gym beam size) and macrodiffraction (mm beam size). A comparison of high-energy X-ray diffraction (XRD) techniques including a powerful two-dimensional XRD method capable of obtaining powder averaged strains from a small number of grains is presented (HEmuXRD2). Using macrodiffraction, the bulk residual strain in the composite was determined against a true strain-free reference. In addition, the bulk in situ response of both the fiber reinforcement and the matrix to tensile stress was observed and compared to a three-dimensional finite element model. Using microdiffraction, multiple strain maps including both phases were collected in situ before, during, and after the application of tensile stress, providing an unprecedented detailed picture of the micromechanical behavior in the laminate metal matrix composite. Finally, the elastic axial strains were compared to predictions from a modified shear lag model, which unlike other shear lag models, considers the elastic response of both constituents. The strains showed excellent correlation with the model. The results confirmed, for the first time, both the need and validity of this new model specifically developed for large scale multifracture and damage evolution simulations of metal matrix composites. The results also provided unprecedented insight for the model, revealing the necessity of incorporating such factors as plasticity of the matrix, residual stress in the composite, and selection of the load sharing parameter. The irradiation of a small number of grains provided strain measurements comparable to a continuum mechanical state in the material. Along the fiber axes, thermal residual stresses of 740 MPa (fibers) and +350 MPa (matrix

  1. Modified silicon carbide whiskers

    DOEpatents

    Tiegs, Terry N.; Lindemer, Terrence B.

    1991-01-01

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  2. Modified silicon carbide whiskers

    DOEpatents

    Tiegs, T.N.; Lindemer, T.B.

    1991-05-21

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  3. Compositional Change of Silicon Carbide Surface due to Oxygen Adsorption and Heat Treatment

    NASA Astrophysics Data System (ADS)

    Minagawa, Hideki; Vina, Raul Oscar; Kadowaki, Tohru; Mizuno, Seigi; Tochihara, Hiroshi; Hayakawa, Kazunobu; Toyoshima, Isamu

    1992-12-01

    The compositional change of the 6H-SiC(10\\bar{1}0) surface was studied under heat treatment and adsorption of oxygen. X-ray photoelectron spectroscopy (XPS) was used for the analysis of the depth composition profile and chemical binding state. After heat treatment, the carbon concentration of the surface was increased due to the surface segregation of the graphite type carbon. When the adsoption of oxygen was performed with heat treatment, the carbon concentration of the surface was increased, but the amount of segregated carbon was less than that of the sample after only heat treatment. The segregated carbon seemed to react with oxygen preferentialy and to desorb from the surface as a carbon monoxide or carbon dioxide.

  4. Asymmetry in body composition in female hockey players.

    PubMed

    Krzykała, M; Leszczyński, P

    2015-08-01

    The aim of the study was to determine if a sport in which one side of the body is dominant, like field hockey, influences regional body composition and bone mineral density (BMD) distribution in particular body segments, and whether the sporting level is a determining factor. Dual energy X-ray absorptiometry (DXA) method (Lunar Prodigy Advance; General Electric, Madison, USA) with the whole body scan was used to measure bone mineral density, fat mass and lean mass in 31 female field hockey players divided according to their sporting level. The morphological asymmetry level was assessed between two body sides and body segments in athletes from the National Team (n=17) and from the Youth Team (n=14) separately and between groups. Bone mineral density in the lower extremity and of the trunk was significantly asymmetric in favor of the left side in the National Team. In the case of the Youth Team, only the trunk BMD indicated clear left-right difference with left side dominance. Both the lean mass and fat mass values were relatively higher on the left side of all body segments and it related to both analyzed groups of athletes. The present study shows that playing field hockey contributes to laterality in body composition and BMD and that the sporting level is a determining factor. In most cases the left side dominated. A greater asymmetry level was observed in more experienced female field hockey players. PMID:26077573

  5. In vivo animal models of body composition in aging

    SciTech Connect

    Yasumura, S. |; Jones, K.; Spanne, P.; Schidlovsky, G.; Wielopolski, L.; Ren, X.; Glaros, D.; Xatzikonstantinou, Y. |

    1992-12-31

    We developed several techniques that provide data on body elemental composition from in vivo measurements in rats. These methods include total body potassium by whole-body counting of endogenous {sup 40}K; total body calcium (TBCa), sodium and chloride by in vivo neutron activation analysis and total body phosphorus (TBP) and nitrogen (TBN) by photon activation analysis. These elements provide information on total body fat, total body protein and skeletal mass. Measurements were made in 6-, 12- and 24-month-old rats. TBN Increased slightly between 6 and 12 months but was significantly lower by 24 months, indicating a substantial loss in total body protein. Working at the National Synchrotron light Source, we studied rat femurs by computed microtomography (CMT), and the elemental profile of the femur cortex by synchrotron-radiation induced X-ray emission (SRIXE). Although there were no significant changes in TBCA and TBP, indices of skeletal mass, CMT revealed a marked increase in the size and number of cavities in the endosteal region of the femur cortex with increasing age. The SRIXE analysis of this cortical bone revealed a parallel decrease in the endosteal Ca/P ratio. Thus, there are major alterations in bone morphology and regional elemental composition despite only modest changes in total skeletal mass.

  6. Aligned Carbon Nanotube Reinforced Silicon Carbide Composites by Chemical Vapor Infiltration

    SciTech Connect

    Gu, Zhan Jun; Yang, Ying Chao; Li, Kai Yuan; Tao, Xin Yong; Eres, Gyula; Howe, Jane Y; Zhang, Li Tong; Li, Xiao Dong; Pan, Zhengwei

    2011-01-01

    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

  7. Body composition analyses in normal weight obese women.

    PubMed

    Di Renzo, L; Del Gobbo, V; Bigioni, M; Premrov, M G; Cianci, R; De Lorenzo, A

    2006-01-01

    The purpose of this study was to identify new indexes of body composition that characterize the normal weight obese (NWO) women. We measured body composition by dual energy x-ray absorptiometry (DXA) and resting metabolic rate (RMR) by indirect calorimetry in a cohort of seventy-five healthy Italian women, subdivided into three groups (nonobese/controls, NWO, preobese-obese women). Despite a normal body mass index (BMI), the NWO women have a higher body fat mass percentage (FAT %) (38.99 +/- 6.03) associated to a significant (p = 0.02) lower amount of lean mass of legs (12.24 +/- 1.31) and lean mass of left leg (6.07 +/- 0.64) with respect to the control group. The NWO group showed a significant (p = 0.043) lower RMR (1201.25 +/- 349.02) in comparison with nonobese and preobese-obese women. To classify NWO individuals among general population, we identified three significant body composition indexes: abdominal index, leg index and trunk index. The NWO women showed significant increased value in the three indexes (p < 0.001). Our results suggest that, despite a normal BMI, the NWO women displayed a cluster of anthropometric characteristics (body fat mass percentage, leg indexes) not different to obese women ones. An appropriate diet-therapy and physical activity may be protecting NWO individuals from diabetes and cardiovascular diseases associated to preobese-obese women.

  8. Body composition and risk for metabolic alterations in female adolescents

    PubMed Central

    de Faria, Eliane Rodrigues; Gontijo, Cristiana Araújo; Franceschini, Sylvia do Carmo C.; Peluzio, Maria do Carmo G.; Priore, Silvia Eloiza

    2014-01-01

    OBJECTIVE: To study anthropometrical and body composition variables as predictors of risk for metabolic alterations and metabolic syndrome in female adolescents. METHODS: Biochemical, clinical and corporal composition data of 100 adolescents from 14 to 17 years old, who attended public schools in Viçosa, Southeastern Brazil, were collected. RESULTS: Regarding nutritional status, 83, 11 and 6% showed eutrophia, overweight/obesity and low weight, respectively, and 61% presented high body fat percent. Total cholesterol presented the highest percentage of inadequacy (57%), followed by high-density lipoprotein (HDL - 50%), low-density lipoprotein (LDL - 47%) and triacylglycerol (22%). Inadequacy was observed in 11, 9, 3 and 4% in relation to insulin resistance, fasting insulin, blood pressure and glycemia, respectively. The highest values of the fasting insulin and the Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) were verified at the highest quartiles of body mass index (BMI), waist perimeter, waist-to-height ratio and body fat percent. Body mass index, waist perimeter, and waist-to-height ratio were the better predictors for high levels of HOMA-IR, blood glucose and fasting insulin. Waist-to-hip ratio was associated to arterial hypertension diagnosis. All body composition variables were effective in metabolic syndrome diagnosis. CONCLUSIONS: Waist perimeter, BMI and waist-to-height ratio showed to be good predictors for metabolic alterations in female adolescents and then should be used together for the nutritional assessment in this age range. PMID:25119752

  9. Determination of body composition in conscious adult female Wistar utilising total body electrical conductivity.

    PubMed

    Dickinson, K; North, T J; Telford, G; Smith, S; Brammer, R; Jones, R B; Heal, D J

    2001-01-01

    Total body electrical conductivity (TOBEC) is a noninvasive method for estimating fat free mass (FFM) in live animals. In this study, we have evaluated the use of the Em-Scan SA-3000, which is claimed by the manufacturers to perform better than earlier analysers. Previous studies in rats using these earlier versions of the TOBEC analyser have always used anaesthesia to minimise movement artefacts. As repeated anaesthesia also has the potential to induce artefacts by disrupting food intake, for example, we have also attempted to determine if this TOBEC analyser can be used to predict body composition in conscious adult weight-stable female Wistar rats. A simplified cafeteria diet was used to produce large variations in body composition (40-350 g fat/carcass) and a full chemical body composition analysis was performed to generate a TOBEC calibration equation. The TOBEC parameter was more strongly correlated to FFM (r(2)=.785) than it was to body weight (r(2)=.669) or other body composition parameters. Using the TOBEC calibration equation to predict fat mass on these data, there was an excellent correlation with the value obtained by chemical analyses (r(2)=.952, slope=0.958). To determine if the TOBEC calibration equation derived from this calibration study would then be useful for the routine estimation of body composition an additional, validation study was performed. This validation study was performed 6 months later, used an independent group of obese female Wistar rats and was undertaken by different TOBEC operators. This validation study, again, showed a good correlation between the TOBEC- and chemical-derived fat mass (r(2)=.918, slope=1.003) indicating stability of the calibration equation with time and independence from operator. We therefore conclude that it is possible to meaningfully estimate body fat changes in conscious rats using this TOBEC analysis system.

  10. Chromium and Iron Isotopic Composition of Presolar Silicon Carbide Stardust Grains

    NASA Astrophysics Data System (ADS)

    Savina, M.; Levine, J.; Dauphas, N.; Pellin, M.; Willingham, D.; Stephan, T.; Trappitsch, R.; Davis, A. M.

    2011-12-01

    Most presolar SiC stardust grains derive from Asymptotic Giant Branch (AGB) stars, which are the main source of s-process nuclides in the galaxy. s-Process nucleosynthesis is not a major contributor to iron peak nuclides. The most interesting of these isotopes from an AGB nucleosynthetic standpoint are the trace isotopes 54Cr and 58Fe, which are predicted to have deviations from average Solar System ratios of ~100% and >200%, respectively. The other isotopes of Cr and Fe are essentially unchanged by AGB stars, and are representative of the isotopic composition of the protostellar cloud from which the SiC grains formed. They are thus tracers of Galactic Chemical Evolution, and provide a benchmark for the isotopic composition of the galaxy some five to seven billion years ago. SiC grains were isolated from the Murchison meteorite using high purity reagents and techniques specifically designed to prevent contamination with terrestrial Cr and Fe. Grains from the 2-4 μm size fraction were pressed into a high purity gold foil. Chromium and iron isotopic compositions were measured by Resonance Ionization Mass Spectrometry (RIMS) using new techniques specifically developed for high precision isotopic analysis of iron-peak elements. The Cr isotopic compositions of 19 grains form a distinct group. Several grains had resolvable (>2σ) 50Cr and 53Cr deficits ranging as low as -178%. The 54Cr/ 52Cr δ-values were all within 2σ of the Solar System value, though most were slightly higher. The average δ-values for the grains were -45±31% for 50Cr, -37±21% for 53Cr, and +25±26% for 54Cr. Iron results are pending. Given that AGB stars change most Fe and Cr isotope ratios very little, and that these grains' progenitor stars formed from a few hundred million to about three billion years before the Solar System formed (assuming their initial masses were 1.5 - 3 solar masses), and that grain interstellar residence times are likely less than ~100 - 200 million years, the Fe and Cr

  11. Body composition and nutrient intake of Buddhist vegetarians.

    PubMed

    Lee, Yujin; Krawinkel, Michael

    2009-01-01

    We described the body composition and nutrient intake of Buddhist vegetarians and compared the data with that of omnivores in South Korea. Vegetarian subjects were 54 Buddhist nuns, who adhered to a vegetarian diet in accordance with Buddhist teachings. We compared these finding with a group of 31 omnivore Catholic nuns who shared a similar lifestyle but different dietary pattern than those of the Buddhist nuns. All subjects completed the estimated three-day dietary record. Body composition was determined by a segmental multi-frequency-bioelectrical impedance analysis method. No height difference between the dietary groups existed but the vegetarians had a significantly higher body weight, fat free mass, body fat and body mass index (BMI, kg/m2) than the omnivores. The median BMI of both vegetarians and omnivores fell in the normal range (22.6 vs. 20.7 kg/m2). In vegetarians, body fat was inversely correlated with the duration of vegetarianism (p for trend=0.043). The long duration group of the vegetarians had lower body fat than the short duration group (12.l vs. 15.0 kg, p=0.032). The status of the nutrient intake of Korean Buddhist vegetarians was comparable to that of omnivores, and the intake of some nutrients in vegetarians was more favorable than in the omnivores.

  12. Reference Values for Body Composition and Anthropometric Measurements in Athletes

    PubMed Central

    Santos, Diana A.; Dawson, John A.; Matias, Catarina N.; Rocha, Paulo M.; Minderico, Cláudia S.; Allison, David B.; Sardinha, Luís B.; Silva, Analiza M.

    2014-01-01

    Background Despite the importance of body composition in athletes, reference sex- and sport-specific body composition data are lacking. We aim to develop reference values for body composition and anthropometric measurements in athletes. Methods Body weight and height were measured in 898 athletes (264 female, 634 male), anthropometric variables were assessed in 798 athletes (240 female and 558 male), and in 481 athletes (142 female and 339 male) with dual-energy X-ray absorptiometry (DXA). A total of 21 different sports were represented. Reference percentiles (5th, 25th, 50th, 75th, and 95th) were calculated for each measured value, stratified by sex and sport. Because sample sizes within a sport were often very low for some outcomes, the percentiles were estimated using a parametric, empirical Bayesian framework that allowed sharing information across sports. Results We derived sex- and sport-specific reference percentiles for the following DXA outcomes: total (whole body scan) and regional (subtotal, trunk, and appendicular) bone mineral content, bone mineral density, absolute and percentage fat mass, fat-free mass, and lean soft tissue. Additionally, we derived reference percentiles for height-normalized indexes by dividing fat mass, fat-free mass, and appendicular lean soft tissue by height squared. We also derived sex- and sport-specific reference percentiles for the following anthropometry outcomes: weight, height, body mass index, sum of skinfold thicknesses (7 skinfolds, appendicular skinfolds, trunk skinfolds, arm skinfolds, and leg skinfolds), circumferences (hip, arm, midthigh, calf, and abdominal circumferences), and muscle circumferences (arm, thigh, and calf muscle circumferences). Conclusions These reference percentiles will be a helpful tool for sports professionals, in both clinical and field settings, for body composition assessment in athletes. PMID:24830292

  13. A study of silicon carbide synthesis from waste serpentine.

    PubMed

    Cheng, T W; Hsu, C W

    2006-06-01

    There are 60000 tons of serpentine wastes produced in year 2004 in Taiwan. This is due to the well-developed joints in the serpentine ore body as well as the stringent requirements of the particle size and chemical composition of serpentine by iron making company. The waste also creates considerable environmental problems. The purpose of this study is reutilization of waste serpentine to produce a high value silica powder after acid leaching. These siliceous microstructure products obtained from serpentine would be responsible for high reactivity and characteristic molecular sieving effect. In this study, the amorphous silica powder was then synthesized to silicon carbide with the C/SiO(2) molar ratio of 3. The experiment results show that silicon carbide can be synthesized in 1550 degrees C. The formed silicon carbide was whisker beta type SiC which can be used as raw materials for industry.

  14. Body size and composition of National Football League players.

    PubMed

    Kraemer, William J; Torine, Jon C; Silvestre, Ricardo; French, Duncan N; Ratamess, Nicholas A; Spiering, Barry A; Hatfield, Disa L; Vingren, Jakob L; Volek, Jeff S

    2005-08-01

    The purpose of this study was to present a profile of body size and composition of National Football League (NFL) players prior to the start of the regular season. Fifty-three members of the Indianapolis Colts professional football team were measured for height, body mass, and percentage body fat using the BOD POD air-displacement plethysmography system during summer camp of the 2003 football season. These data were categorized by position for comparison with previous studies of NFL football players. The relationships observed were as follows (= represents nonsignificant; > represents p < or = 0.05): Height: Offensive Line = Defensive Line = Quarterbacks/Kickers/Punters = Tight Ends > Linebackers > Running Backs = Wide Receivers = Defensive Backs. Body Mass: Offensive Line = Defensive Line > Tight Ends = Linebackers > Running Backs = Quarterbacks/ Kickers/Punters > Wide Receivers = Defensive Backs. Percentage Body Fat: Offensive Line > Defensive Line > Quarterbacks/ Kickers/Punters = Linebackers = Tight Ends > Running Backs = Wide Receivers = Defensive Backs. Comparisons to teams in the 1970s indicate that body mass has increased only for offensive and defensive linemen; however, height and body fat among player positions have not dramatically changed. Furthermore, the body mass index is not an accurate measure or representation of body fat or obesity in NFL players. These data provide a basic template for size profiles and differences among various positions and allow comparisons with other studies for changes in the NFL over the past 3 decades.

  15. CORRELATED STRONTIUM AND BARIUM ISOTOPIC COMPOSITIONS OF ACID-CLEANED SINGLE MAINSTREAM SILICON CARBIDES FROM MURCHISON

    SciTech Connect

    Liu, Nan; Davis, Andrew M.; Dauphas, Nicolas; Pellin, Michael J.; Savina, Michael R.; Gallino, Roberto; Bisterzo, Sara; Gyngard, Frank; Käppeler, Franz; Cristallo, Sergio; Dillmann, Iris

    2015-04-10

    We present strontium, barium, carbon, and silicon isotopic compositions of 61 acid-cleaned presolar SiC grains from Murchison. Comparison with previous data shows that acid washing is highly effective in removing both strontium and barium contamination. For the first time, by using correlated {sup 88}Sr/{sup 86}Sr and {sup 138}Ba/{sup 136}Ba ratios in mainstream SiC grains, we are able to resolve the effect of {sup 13}C concentration from that of {sup 13}C-pocket mass on s-process nucleosynthesis, which points toward the existence of large {sup 13}C pockets with low {sup 13}C concentrations in asymptotic giant branch stars. The presence of such large {sup 13}C pockets with a variety of relatively low {sup 13}C concentrations seems to require multiple mixing processes in parent asymptotic giant branch stars of mainstream SiC grains.

  16. Correlated Strontium and Barium Isotopic Compositions of Acid-cleaned Single Mainstream Silicon Carbides from Murchison

    NASA Astrophysics Data System (ADS)

    Liu, Nan; Savina, Michael R.; Gallino, Roberto; Davis, Andrew M.; Bisterzo, Sara; Gyngard, Frank; Käppeler, Franz; Cristallo, Sergio; Dauphas, Nicolas; Pellin, Michael J.; Dillmann, Iris

    2015-04-01

    We present strontium, barium, carbon, and silicon isotopic compositions of 61 acid-cleaned presolar SiC grains from Murchison. Comparison with previous data shows that acid washing is highly effective in removing both strontium and barium contamination. For the first time, by using correlated 88Sr/86Sr and 138Ba/136Ba ratios in mainstream SiC grains, we are able to resolve the effect of 13C concentration from that of 13C-pocket mass on s-process nucleosynthesis, which points toward the existence of large 13C pockets with low 13C concentrations in asymptotic giant branch stars. The presence of such large 13C pockets with a variety of relatively low 13C concentrations seems to require multiple mixing processes in parent asymptotic giant branch stars of mainstream SiC grains.

  17. Physique and Body Composition in Soccer Players across Adolescence

    PubMed Central

    Nikolaidis, Pantelis Theodoros; Vassilios Karydis, Nikos

    2011-01-01

    Purpose Although the contribution of physique and body composition in soccer performance was recognized, these parameters of physical fitness were not well-studied in adolescent players. Aim of this study was to investigate physique and body composition across adolescence. Methods Male adolescents (N=297 aged 12.01–20.98 y), classified into nine one-year age-groups, child (control group, N=16 aged 7.34–11.97 y) and adult players (control group, N=29 aged 21.01–31.59 y), all members of competitive soccer clubs, performed a series of anthropometric measures (body mass, height, skinfolds, circumferences and girths), from which body mass index (BMI), percentage of body fat (BF%), fat mass (FM), fat free mass (FFM) and somatotype (Heath-Carter method) were calculated. Results Age had a positive association with FM (r=0.2, P<0.001) and FFM (r=0.68, P<0.001), and a negative association with BF (r=−0.12, P=0.047). Somatotype components changed across adolescence as well; age was linked to endomorphy (r=−0.17, P=0.005), mesomorphy (r=0.14, P=0.019) and ectomorphy (r=−0.17, P=0.004). Compared with age-matched general population, participants exhibited equal body mass, higher stature, lower body mass index and lower BF. Conclusion During adolescence, soccer players presented significant differences in terms of body composition and physique. Thus, these findings could be employed by coaches and fitness trainers engaged in soccer training in the context of physical fitness assessment and talent identification. PMID:22375222

  18. Assessment and Interpretation of Body Composition in Physical Education

    ERIC Educational Resources Information Center

    Vehrs, Pat; Hager, Ron

    2006-01-01

    The physical educator's role is evolving into that of a teacher who is well educated in the areas of teaching, skill acquisition and development, motor learning, exercise physiology, physical conditioning, weight management, health, and lifestyle management. In an era when childhood obesity is at an all-time high, body composition can be one…

  19. Design for manufacturability evaluation: Composite NIF Pockel Cell body

    SciTech Connect

    Jensen, W.A.; Spellman, G.P.

    1994-04-01

    A survey of composite materials and processes for the NIF Optical Switch Body is described. Mechanical and physical criterion set upon the part are used as guidelines for the selection of materials and processes for manufacturing. Benefits, costs, and risks associated with selected processes, as well as a recommendation for prototype fabrication is presented.

  20. Effect of chronic centrifugation on body composition in the rat.

    NASA Technical Reports Server (NTRS)

    Pitts, G. C.; Bull, L. S.; Oyama, J.

    1972-01-01

    Two groups of adult female rats were chronically centrifuged for 60 days (2.76 G, 4.15 G, controls at 1.00 G). Live weights of centrifugal rats decreased about 20 g (6%) per Delta 1 G above control. This weight loss comprised reductions in both body fat and fat-free body weight (FFBW) as determined by body-composition studies on eight rats per group killed at the end of centrifugation. Of nine components constituting the FFBW, only skeletal muscle, liver, and heart changed significantly in weight. Chemical composition showed reductions (compared with controls) in the fat fraction of most components and increases in the water fraction of liver and gut. Identical measurements were made on the remaining eight rats per group killed 43 days after return to 1 G. Neither centrifuged group had reached the control body-weight level at this time. No statistically significant effect of previous G level was found in any of the body-composition parameters. The possible involvment of physiological regulation was considered.

  1. Body composition comparison in two elite female wheelchair athletes.

    PubMed

    Lussier, L; Knight, J; Bell, G; Lohman, T; Morris, A F

    1983-02-01

    It was the purpose of this study to determine body composition by two methods in two excellent female athletes. One sportswoman (SRH) was national wheelchair marathon champion in 1977 in 3 hours, 40 minutes on the Boston course. She still competes internationally and has won three gold medals and set three world records in the last Olympiad for the handicapped in 1980. The second woman athlete (LSJ) competes in wheelchair basketball and track on a national level. Body density was determined by the standard underwater weighing procedure and residual volume determination. A second method to calculate cellular body mass was the measure of potassium 40 (40K) activity by whole body scintillation counter. The characteristics of these athletes are listed as follows: (formula; see text) The results show that both methods of determining adiposity produce results differing by only one percentage point. It is important to determine body composition in these wheelchair athletes since their cellular body mass is decreased because of their disability.

  2. Effects of weightlessness on body composition in the rat

    NASA Technical Reports Server (NTRS)

    Pitts, G. C.; Ushakov, A. S.; Pace, N.; Smith, A. H.; Rahlmann, D. F.; Smirnova, T. A.

    1983-01-01

    The effects of weightlessness on the body composition of rats were investigated using 5 male rats exposed to 18.5 days of weightlessness on the COSMOS 1129 biosatellite and killed after reentry. The animals were immediately dissected and the three major body divisions (musculoskeletal system, skin, and pooled viscera) were analyzed for fat, water, solids, and six elements. These results were determined as percentages of the fat-free body or its components and then compared with two groups of terrestrial controls, one of which was subjected to a flight simulation in a spacecraft mock-up while the other was under standard vivarium conditions. Compared with the control groups, the flight group was found to exhibit a reduced fraction of total body water, a net shift of body water from skin to viscera, a marked diminution in the fraction of extracellular water in the fat-free body, a marked reduction in the fraction of bone mineral, no change in the quantity of stored fat or adrenal masses, and a net increase in total muscle mass as indicated by total body creatine, protein, and body cell mass.

  3. Isotopic compositions of s-process elements in acid-cleaned mainstream presolar silicon carbide

    NASA Astrophysics Data System (ADS)

    Liu, Nan

    Pristine meteorites contain ancient stellar relicts that survived destructions in the early solar system. Isotopic studies of these presolar grains have proven to be a unique method to understand various known and unknown nucleosynthetic processes occurred in their parent stars. Previous studies of isotopic compositions of heavy elements in mainstream SiC grains from low-mass asymptotic giant branch (AGB) stars reported contamination from solar system materials with normal isotopic compositions on grain surfaces and prevented the authors from obtaining the pure nucleosynthetic isotopic signature from stars. In addition, in these previous studies uncertainties in the major neutron source 13C within the 13C-pocket were underestimated because only the 13C mass fraction was considered as a parameter with the 13C-pocket mass and the 13C profile fixed in model calculations. The oversimplified treatment of the 13C-pocket mainly resulted from the fact that it was unclear if there exists any tracer to distinguish different effects of the 13C concentration, the 13C-pocket mass, and the 13C profile within the 13C-pocket. To address these issues, we acid-cleaned all the presolar SiC grains used in this study after their separation from the bulk Murchison meteorite. In addition, we chose to measure strontium and barium isotopic compositions in these acid-cleaned SiC grains, because both elements sit at the first and second s-process peaks along the s-process path, and are sensitive to varying parameters for the s-process in model calculations. By comparing our new acid-cleaned grain data with single grain data from previous studies for barium isotopes, we conclude that the acid-cleaning procedure is quite effective in removing surface barium contamination. For the first time, we find that model predictions for 138Ba/ 136Ba are sensitive to all three variables of the 13C-pocket adopted in AGB model calculations. In order to match the low 138Ba/ 136Ba values in a minor group of

  4. Fivefold twinned boron carbide nanowires.

    PubMed

    Fu, Xin; Jiang, Jun; Liu, Chao; Yuan, Jun

    2009-09-01

    Chemical composition and crystal structure of fivefold twinned boron carbide nanowires have been determined by electron energy-loss spectroscopy and electron diffraction. The fivefold cyclic twinning relationship is confirmed by systematic axial rotation electron diffraction. Detailed chemical analysis reveals a carbon-rich boron carbide phase. Such boron carbide nanowires are potentially interesting because of their intrinsic hardness and high temperature thermoelectric property. Together with other boron-rich compounds, they may form a set of multiply twinned nanowire systems where the misfit strain could be continuously tuned to influence their mechanical properties.

  5. Gamma resonance absorption. New approach in human body composition studies.

    PubMed

    Wielopolski, L; Vartsky, D; Pierson, R; Goldberg, M; Heymsfield, S; Yasumura, S; Melnychuk, S T; Sredniawski, J

    2000-05-01

    The main stream of body elemental analysis is based on the delayed, prompt, and inelastic neutron interactions with the main elements found in the human body, and subsequent analysis of the measured delayed or prompt gamma ray spectra. This methodology traditionally was, and still is, applied for whole body analysis and requires relatively high radiation doses. A new method, based on gamma nuclear resonance absorption (GNRA), is being established at Brookhaven National Laboratory as part of its body composition program. The method is element specific with a high tomographic spatial-resolution capability, at a small fraction of the radiation dose used in the current system. The new system, with its components and capabilities, is described below. PMID:10865747

  6. Analysis of Relationship between the Body Mass Composition and Physical Activity with Body Posture in Children

    PubMed Central

    Baran, Joanna; Czenczek-Lewandowska, Ewelina; Leszczak, Justyna; Mazur, Artur

    2016-01-01

    Introduction. Excessive body mass in turn may contribute to the development of many health disorders including disorders of musculoskeletal system, which still develops intensively at that time. Aim. The aim of this study was to assess the relationship between children's body mass composition and body posture. The relationship between physical activity level of children and the parameters characterizing their posture was also evaluated. Material and Methods. 120 school age children between 11 and 13 years were enrolled in the study, including 61 girls and 59 boys. Each study participant had the posture evaluated with the photogrammetric method using the projection moiré phenomenon. Moreover, body mass composition and the level of physical activity were evaluated. Results. Children with the lowest content of muscle tissue showed the highest difference in the height of the inferior angles of the scapulas in the coronal plane. Children with excessive body fat had less slope of the thoracic-lumbar spine, greater difference in the depth of the inferior angles of the scapula, and greater angle of the shoulder line. The individuals with higher level of physical activity have a smaller angle of body inclination. Conclusion. The content of muscle tissue, adipose tissue, and physical activity level determines the variability of the parameter characterizing the body posture. PMID:27761467

  7. ["In vivo" body composition assessment; part I: a historic overview].

    PubMed

    Carnero, Elvis A; Alvero-Cruz, José Ramón; Giráldez García, Manuel Avelino; Sardinha, Luis B

    2015-05-01

    The study of body composition (BC) has gained in relevance over the last decades, mainly because of its important health- and disease- related applications within both the clinical and the sports setting. It is not a new area, and its especial relevance as an area of biology dates from the second half of the nineteenth century. In this paper, we have reviewed the three historic periods of BC, with special reference to the most important advances in in vivo assessment. Even though the earliest findings about human BC date from antiquity, the first (or 'early') stage of discovery began in 1850. Said early stage was mainly characterized by data obtained from the dissection of cadavers and by the application of biochemical methods in vivo. Longitudinal changes in body composition were also a concern. The second (so called 'recent') stage, in the second half of the twentieth century, was marked by milestones such as the formulation of the first mathematical models for the estimation of body components, and technological advances. Within the third ('contemporary' or 'current') stage of research, several groups have focused on validating the classical BC models in specific populations, on analysis of the genetic determinants (i.e. phenotypes and, more recently genotypes) of body composition, and on re-instigating the study of dynamic BC.

  8. ["In vivo" body composition assessment; part I: a historic overview].

    PubMed

    Carnero, Elvis A; Alvero-Cruz, José Ramón; Giráldez García, Manuel Avelino; Sardinha, Luis B

    2015-01-01

    The study of body composition (BC) has gained in relevance over the last decades, mainly because of its important health- and disease- related applications within both the clinical and the sports setting. It is not a new area, and its especial relevance as an area of biology dates from the second half of the nineteenth century. In this paper, we have reviewed the three historic periods of BC, with special reference to the most important advances in in vivo assessment. Even though the earliest findings about human BC date from antiquity, the first (or 'early') stage of discovery began in 1850. Said early stage was mainly characterized by data obtained from the dissection of cadavers and by the application of biochemical methods in vivo. Longitudinal changes in body composition were also a concern. The second (so called 'recent') stage, in the second half of the twentieth century, was marked by milestones such as the formulation of the first mathematical models for the estimation of body components, and technological advances. Within the third ('contemporary' or 'current') stage of research, several groups have focused on validating the classical BC models in specific populations, on analysis of the genetic determinants (i.e. phenotypes and, more recently genotypes) of body composition, and on re-instigating the study of dynamic BC. PMID:25929363

  9. Gender Differences in Insulin Resistance, Body Composition, and Energy Balance

    PubMed Central

    Geer, Eliza B.; Shen, Wei

    2010-01-01

    Background Men and women differ substantially in regard to degrees of insulin resistance, body composition, and energy balance. Adipose tissue distribution, in particular the presence of elevated visceral and hepatic adiposity, plays a central role in the development of insulin resistance and obesity-related complications. Objective This review summarizes published data on gender differences in insulin resistance, body composition, and energy balance, to provide insight into novel gender-specific avenues of research as well as gender-tailored treatments of insulin resistance, visceral adiposity, and obesity. Methods English-language articles were identified from searches of the PubMed database through November 2008, and by reviewing the references cited in these reports. Searches included combinations of the following terms: gender, sex, insulin resistance, body composition, energy balance, and hepatic adipose tissue. Results For a given body mass index, men were reported to have more lean mass, women to have higher adiposity. Men were also found to have more visceral and hepatic adipose tissue, whereas women had more peripheral or subcutaneous adipose tissue. These differences, as well as differences in sex hormones and adipokines, may contribute to a more insulin-sensitive environment in women than in men. When normalized to kilograms of lean body mass, men and women had similar resting energy expenditure, but physical energy expenditure was more closely related to percent body fat in men than in women. Conclusion Greater amounts of visceral and hepatic adipose tissue, in conjunction with the lack of a possible protective effect of estrogen, may be related to higher insulin resistance in men compared with women. PMID:19318219

  10. Inferences from other bodies for the earth's composition and evolution

    NASA Technical Reports Server (NTRS)

    Kaula, W. M.

    1981-01-01

    Properties of the earth are considered in the light of the earth's presumed status as an end member of the class of predominantly silicate solar system bodies. Bulk composition data for the inner planets are presented and processes which may account for compositional variations are discussed. Problems posed by Viking findings on Mars and Pioneer findings on Venus are mentioned. Prominent evolutionary patterns of the inner planets are discussed, including the inverse correlation of lithospheric and crustal thickness with planetary size, and the thermotectonics of Venus, Mars, and earth are compared.

  11. Chemical compositions of the moon, earth, and eucrite parent body

    NASA Technical Reports Server (NTRS)

    Anders, E.

    1977-01-01

    Model compositions of the moon and earth were calculated on the assumption that these planets had experienced chondrite-like nebular fractionation processes. The model correctly predicts the abundance ratios of certain volatile/refractory element pairs (e.g., Cd/Ba, Ga/La, Sn/Th, and Pb/U), the density of the moon, and the major rock types. The model is also used to reconstruct the composition of the parent eucrite body, which resembles the moon except for a lower content of refractory elements.

  12. Nutrition, endocrinology, and body composition during space flight

    NASA Technical Reports Server (NTRS)

    Lane, H. W.; Gretebeck, R. J.; Smith, S. M.

    1998-01-01

    Space flight induces endocrine changes that perturb metabolism. This altered metabolism affects both the astronauts' body composition and the nutritional requirements necessary to maintain their health. During the last 25 years, a combination of studies conducted on Skylab (the first U.S. space laboratory), U.S. Shuttle flights, and Soviet and Russian flights provides a range of data from which general conclusions about energy and protein requirements can be drawn. We have reviewed the endocrine data from those studies and related it to changes in body composition. From these data it appears that protein and energy intake of astronauts are similar to those on Earth. However, a combination of measures, including exercise, appropriate diet, and, potentially, drugs, is required to provide the muscle health needed for long duration space flight.

  13. Composition and function of P bodies in Arabidopsis thaliana

    PubMed Central

    Maldonado-Bonilla, Luis D.

    2014-01-01

    mRNA accumulation is tightly regulated by diverse molecular pathways. The identification and characterization of enzymes and regulatory proteins involved in controlling the fate of mRNA offers the possibility to broaden our understanding of posttranscriptional gene regulation. Processing bodies (P bodies, PB) are cytoplasmic protein complexes involved in degradation and translational arrest of mRNA. Composition and dynamics of these subcellular structures have been studied in animal systems, yeasts and in the model plant Arabidopsis. Their assembly implies the aggregation of specific factors related to decapping, deadenylation, and exoribonucleases that operate synchronously to regulate certain mRNA targets during development and adaptation to stress. Although the general function of PB along with the flow of genetic information is understood, several questions still remain open. This review summarizes data on the composition, potential molecular roles, and biological significance of PB and potentially related proteins in Arabidopsis. PMID:24860588

  14. Sarcopenia and the Analysis of Body Composition12

    PubMed Central

    Ribeiro, Sandra M. L.; Kehayias, Joseph J.

    2014-01-01

    Reduction of lean mass is a primary body composition change associated with aging. Because many factors contribute to lean mass reduction, the problem has been given various names depending on the proposed cause, such as “age-related sarcopenia,” “dynapenia,” “myopenia,” “sarcopenic obesity,” or simply “sarcopenia.” There is currently no consensus on how to best diagnose the reduction of lean mass and its consequences on health. We propose that simple body composition methods can be used to indirectly evaluate sarcopenia, provided that those techniques are validated against the “quality of lean” criterion that associates muscle mass and metabolic function with the components of fat-free mass. Promising field methods include the use of stable isotopes for the evaluation of water compartments and new approaches to bioelectrical impedance analysis, which is also associated with the monitoring of water homeostasis. PMID:24829472

  15. Compositions for depolluting fresh water and salt water bodies

    SciTech Connect

    Olivieri, R.; Degen, L.; Robertiello, A.

    1983-11-08

    Compositions are disclosed, which are adapted to depollute fresh and sea water bodies from crude oil and petroleum product pollution by microbial action. The growth of micro-organisms capable of metabolizing hydrocarbons is exalted by certain combination of nutrients, such as lecithin as a phosphorus source, hydantoins, amides allophanates, polyamines, acyl-ureas and esters of the hydantoic and allantoic acids as the nitrogen sources. Ureido-derivatives of amides are also contemplated as additional nutrients.

  16. Anorexia nervosa and nutritional assessment: contribution of body composition measurements.

    PubMed

    Mattar, Lama; Godart, Nathalie; Melchior, Jean Claude; Pichard, Claude

    2011-06-01

    The psychiatric condition of patients suffering from anorexia nervosa (AN) is affected by their nutritional status. An optimal assessment of the nutritional status of patients is fundamental in understanding the relationship between malnutrition and the psychological symptoms. The present review evaluates some of the available methods for measuring body composition in patients with AN. We searched literature in Medline using several key terms relevant to the present review in order to identify papers. Only articles in English or French were reviewed. A brief description is provided for each body composition technique, with its applicability in AN as well as its limitation. All methods of measuring body composition are not yet validated and/or feasible in patients with AN. The present review article proposes a practical approach for selecting the most appropriate methods depending on the setting, (i.e. clinical v. research) and the goal of the assessment (initial v. follow-up) in order to have a more personalised treatment for patients suffering from AN.

  17. Protein composition of oil bodies from mature Brassica napus seeds.

    PubMed

    Jolivet, Pascale; Boulard, Céline; Bellamy, Annick; Larré, Colette; Barre, Marion; Rogniaux, Hélène; d'Andréa, Sabine; Chardot, Thierry; Nesi, Nathalie

    2009-06-01

    Seed oil bodies (OBs) are intracellular particles storing lipids as food or biofuel reserves in oleaginous plants. Since Brassica napus OBs could be easily contaminated with protein bodies and/or myrosin cells, they must be purified step by step using floatation technique in order to remove non-specifically trapped proteins. An exhaustive description of the protein composition of rapeseed OBs from two double-zero varieties was achieved by a combination of proteomic and genomic tools. Genomic analysis led to the identification of sequences coding for major seed oil body proteins, including 19 oleosins, 5 steroleosins and 9 caleosins. Most of these proteins were also identified through proteomic analysis and displayed a high level of sequence conservation with their Arabidopsis thaliana counterparts. Two rapeseed oleosin orthologs appeared acetylated on their N-terminal alanine residue and both caleosins and steroleosins displayed a low level of phosphorylation.

  18. Protein composition of oil bodies from mature Brassica napus seeds.

    PubMed

    Jolivet, Pascale; Boulard, Céline; Bellamy, Annick; Larré, Colette; Barre, Marion; Rogniaux, Hélène; d'Andréa, Sabine; Chardot, Thierry; Nesi, Nathalie

    2009-06-01

    Seed oil bodies (OBs) are intracellular particles storing lipids as food or biofuel reserves in oleaginous plants. Since Brassica napus OBs could be easily contaminated with protein bodies and/or myrosin cells, they must be purified step by step using floatation technique in order to remove non-specifically trapped proteins. An exhaustive description of the protein composition of rapeseed OBs from two double-zero varieties was achieved by a combination of proteomic and genomic tools. Genomic analysis led to the identification of sequences coding for major seed oil body proteins, including 19 oleosins, 5 steroleosins and 9 caleosins. Most of these proteins were also identified through proteomic analysis and displayed a high level of sequence conservation with their Arabidopsis thaliana counterparts. Two rapeseed oleosin orthologs appeared acetylated on their N-terminal alanine residue and both caleosins and steroleosins displayed a low level of phosphorylation. PMID:19562800

  19. Body composition and nutritional profile of male adolescent tennis players.

    PubMed

    Juzwiak, Claudia R; Amancio, Olga M S; Vitalle, Maria S S; Pinheiro, Marcelo M; Szejnfeld, Vera L

    2008-09-01

    In this cross-sectional study, we evaluated the body composition and dietary intake of 44 adolescent tennis players. After being divided into two groups (age 10-13 years and age 14-18), the players had their weight, height, and sexual maturation assessed. Dual-energy X-ray absorptiometry was used to assess body composition. Food intake was obtained from a non-consecutive 4-day food record. The data were analysed using the Virtual Nutri v.1.0 software and compared with the present recommendations for adolescent athletes or dietary reference intakes. Body mass index and body fat for tennis practice were adequate for 89% and 71% of the tennis players respectively, regardless of age group. A calorie deficit greater than 10% of energy expenditure was observed in 32% of the sample. Fifty percent of the athletes consumed carbohydrates in accordance with recommended values. Protein and lipid intakes were above recommended values, while fibre, calcium, potassium, magnesium, and folic acid intakes were below recommendation for 98%, 80%, 100%, 100%, and 98% of the tennis players respectively. The observed nutritional deficiencies represent an additional barrier for adolescents engaged in competitive sports to achieve an optimum nutrition to maintain growth, health, and performance.

  20. Total body composition by dual-photon (153Gd) absorptiometry

    SciTech Connect

    Mazess, R.B.; Peppler, W.W.; Gibbons, M.

    1984-10-01

    The lean-fat composition (%FATR) of soft tissue and the mineral mass of the skeleton were determined in vivo using dual-photon (153Gd) absorptiometry (dose under 2 mrem). A rectilinear raster scan was made over the entire body in 18 subjects (14 female, 4 male). Single-photon absorptiometry (125I) measured bone mineral content on the radius. Percentage fat (%FATD) was determined in the same subjects using body density (from underwater weighing with correction for residual lung volume). Lean body mass (LBM) was determined using both %FATR and %FATD. Percentage fat from absorptiometry and from underwater density were correlated (r . 0.87). The deviation of %FATD from %FATR was due to the amount of skeletal mineral as a percentage of the LBM (r . 0.90). Therefore, skeletal variability, even in normal subjects, where mineral ranges only from 4 to 8% of the LBM, essentially precludes use of body density as a composition indicator unless skeletal mass is measured. Anthropometry (fatfolds and weight) predicted %FATR and LBM at least as well as did underwater density. The predictive error of %FATR from fatfolds was 5% while the predictive error in predicting LBM from anthropometry was 2 to 3 kg (3%).

  1. Heterogeneous composite bodies with isolated lenticular shaped cermet regions

    SciTech Connect

    Sherman, Andrew J.

    2009-12-22

    A heterogeneous body having ceramic rich cermet regions in a more ductile metal matrix. The heterogeneous bodies are formed by thermal spray operations on metal substrates. The thermal spray operations apply heat to a cermet powder and project it onto a solid substrate. The cermet powder is composed of complex composite particles in which a complex ceramic-metallic core particle is coated with a matrix precursor. The cermet regions are generally comprised of complex ceramic-metallic composites that correspond approximately to the core particles. The cermet regions are approximately lenticular shaped with an average width that is at least approximately twice the average thickness. The cermet regions are imbedded within the matrix phase and generally isolated from one another. They have obverse and reverse surfaces. The matrix phase is formed from the matrix precursor coating on the core particles. The amount of heat applied during the formation of the heterogeneous body is controlled so that the core particles soften but do not become so fluid that they disperse throughout the matrix phase. The force of the impact on the surface of the substrate tends to flatten them. The flattened cermet regions tend to be approximately aligned with one another in the body.

  2. Bioimpedance measurements of human body composition: critical analysis and outlook.

    PubMed

    Matthie, James R

    2008-03-01

    Bioimpedance spectroscopy represents one of the largest emerging medical device technologies. The method is generally known as impedance spectroscopy and is an inexpensive, yet extremely powerful, analytical technique for studying the electrical properties of materials. Much of what we know about biological cells and tissues comes from use of this technique in vitro. Due to the high impedance of the cell membrane, current flow through the cell is frequency dependent and this allows the fluid volume inside versus outside the body's cells to be determined. The fluid outside the cells is primarily related to fluid volume status while the intracellular fluid also relates to the body's cellular mass. Technical advances have removed much of the method's basic complexities. The first commercial bioimpedance spectroscopy device for in vivo human body composition studies was introduced in 1990. Major strides have been made and the method is now poised to enter mainstream clinical medicine but the field is only in its infancy. This paper attempts to fully describe the current use of impedance in the body composition field.

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

    NASA Astrophysics Data System (ADS)

    Park, Joon Seok

    2008-10-01

    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 compound also retains the extreme hardness of the artificial gem. This makes it difficult to perform structural analysis by transmission electron microscopy (TEM), for it is not possible to produce thin foils out of this solid by conventional polishing methods. For the first time, a dual-beam focused ion beam (FIB) instrument successfully allowed site-specific preparation of electron-transparent specimens by the lift-out technique. Subsequent TEM studies revealed that the highest concentration of structural defects occurs in the vicinity of the diamond-SiC interfaces, which are believed to act as the major barriers to the transport of thermal energy. Diffraction contrast analyses showed that the majority of the defects in diamond are isolated perfect screw or 60° dislocations. On the other hand, SiC grains contain partial dislocations and a variety of imperfections such as microtwins, stacking faults and planar defects that are conjectured to consist of antiphase (or inversion) boundaries. Clusters of nanocrystalline SiC were also observed at the diamond-SiC boundaries, and a specific heteroepitaxial orientation relationship was discovered for all cubic SiC that grows on diamond {111} facets. Yttria-stabilized Zirconia (YSZ) is the most common electrolyte material for solid oxide fuel cell (SOFC) applications. It is an ionic conductor in which charge transfer is achieved by the transport of oxygen ions (O 2-). Like the diamond composite above, it is hard and brittle, and difficult to make into electron transparent TEM samples. Provided an effective

  4. Spark Plasma Sintering of Aluminum-Magnesium-Matrix Composites with Boron Carbide and Tungsten Nano-powder Inclusions: Modeling and Experimentation

    NASA Astrophysics Data System (ADS)

    Dvilis, E. S.; Khasanov, O. L.; Gulbin, V. N.; Petyukevich, M. S.; Khasanov, A. O.; Olevsky, E. A.

    2016-03-01

    Spark-plasma sintering (SPS) is used to fabricate fully-dense metal-matrix (Al/Mg) composites containing hard ceramic (boron carbide) and refractory metal (tungsten) inclusions. The study objectives include the modeling (and its experimental verification) of the process of the consolidation of the composites consisted of aluminum-magnesium alloy AMg6 (65 wt.%), B4C powder (15 wt.%), and W nano-powder (20 wt.%), as well as the optimization of the composite content and of the SPS conditions to achieve higher density. Discrete element modeling of the composite particles packing based on the particle size distribution functions of real powders is utilized for the determination of the powder compositions rendering maximum mixture packing densities. Two models: a power-law creep model of the high temperature deformation of powder materials, and an empirical logarithmic pressure-temperature-relative density relationship are successfully applied for the description of the densification of the aluminum-magnesium metal matrix powder composite subjected to spark-plasma sintering. The elastoplastic properties of the sintered composite samples are assessed by nanoindentation.

  5. Gravity, Body Mass and Composition, and Metabolic Rate

    NASA Technical Reports Server (NTRS)

    Pace, N.; Smith, A. H.

    1985-01-01

    Metabolic rate and body composition as a function of sex and age were defined in 5 species of common laboratory mammals, the mouse, hamster, rat, guinea pig and rabbit. Oxygen consumption and carbon dioxide production rates were measured individually in 6 male and 6 female animals for each of 8 age cohorts ranging from 1 month to 2 years, and for each of the species. From the results it is evident that among these small mammals there is no indication of scaling of muscularity to body size, despite the 100-fold difference in body mass represented by the skeletal musculature seems to reach a pronounced peak value at age 2 to 3 months and then declines, the fraction of the fat-free body represented by other body components in older animals must increase complementarily. Under normal gravity conditions muscularity in small laboratory mammals displays large, systematic variation as a function both of species and age. This variation must be considered when such animals are subjects of experiments to study the effects of altered gravitational loading on the skeletal musculature of the mammal.

  6. Body composition in human infants at birth and postnatally.

    PubMed

    Koo, W W; Walters, J C; Hockman, E M

    2000-09-01

    The predictive values of anthropometric measurements, race, gender, gestational and postnatal ages, and season at birth and at study for the total body dual energy X-ray absorptiometry (DXA)-derived lean mass (LM), fat mass (FM) and fat mass as a percentage of body weight (%FM) were determined in 214 singleton appropriate birth weight for gestational age infants [101 Caucasian (60 boys, 41 girls) and 113 African American (55 boys, 58 girls)]. Gestational ages were 27-42 wk and the infants were studied between birth and 391 d, weighing between 851 and 13446 g. In addition, predictive value of body weight, LM and FM for DXA bone measurements was also determined. Scan acquisition used Hologic QDR 1000/W densitometer and infant platform and scans without significant movement artifacts were analyzed using software 5.64p. Body weight, length, gender and postnatal age were significant predictors of LM (adjusted R:(2) >0. 94) and FM (adjusted R:(2) >0.85). Physiologic variables had little predictive value for %FM except in the newborns (adjusted R:(2) 0. 69). Body weight was the dominant predictor of LM and FM, although length had similar predictive value for LM with increasing postnatal age. Female infants had less LM and more FM throughout infancy (P: < 0.01). LM or FM offered no advantage over body weight in the prediction of bone mass measurements. DXA is a useful means with which to determine body composition, and our data are important in the design and assessment of nutritional intervention studies.

  7. Computer technology to evaluate body composition, nutrition, and exercise.

    PubMed

    Katch, F I; Katch, V L

    1983-09-01

    The use of computer technology has made it possible to make accurate determinations of body composition, nutrition, and exercise. With the FITCOMP computer assessment system, detailed measurements of physique status have been made on a variety of world-class athletes, including professional football and baseball players, as well as on diverse groups of young and older men and women throughout the United States. The FITCOMP measurement system allows the user a choice of measurement techniques: fatfolds, girths, bone diameters, and hydrostatic weighing. Combined with body composition assessment is a nutrition and exercise plan. The nutrition plan is based on guidelines formulated by the American Dietetic Association. This application of computer technology is unique, because individuals can select the foods they will eat from a list of preferred choices from the basic food groups. Individual menu plans for breakfast, lunch, and dinner are generated to provide an optimal blend of nutrients aimed at achieving ideal body mass and fat percentage. This is coupled with an aerobic exercise program that is selected by the individual from nine different forms, including walking, jogging, running, swimming, cycling, and various sport activities. The caloric output is designed to reduce total body fat through reductions in body weight of 1.4 to 2.5 pounds per week, depending on the exercise selected and total weight loss necessary to achieve a weight goal (and ideal fat percentage). The aerobic exercise plan is based on the method of overload, where intensity and duration are periodically increased dependent on individual capabilities. The use of fitness-oriented computer technology makes it possible to prepare detailed reports about current status and progress as well as to systematize record keeping.

  8. What is the impact of Silicon Carbide nanoparticles to the mineral composition of rat lungs? A PIXE-μPIXE comparative study

    NASA Astrophysics Data System (ADS)

    Lozano, O.; Colaux, J. L.; Laloy, J.; Dogné, J. M.; Lucas, S.

    2015-05-01

    The exposure to nanomaterials can yield changes in the mineral composition of tissues which may have long term health repercussions. In this study, the changes in mineral composition of rat lungs, exposed to a nanoaerosol of silicon carbide (SiC), has been studied by means of global and local ion beam probes with the Particle-Induced X-ray Emission (PIXE) technique, measuring the whole lung contents and selected areas where SiC was found, respectively. It was found that from a global perspective there is a small decrease in the mineral contents (phosphorous, sulphur, chlorine and potassium) of the lung except for Ca, while locally these mineral contents tend fluctuate.

  9. Nutritional Markers and Body Composition in Hemodialysis Patients

    PubMed Central

    Valtuille, Rodolfo; Casos, Maria Elisa; Fernandez, Elmer Andres; Guinsburg, Adrian; Marelli, Cristina

    2015-01-01

    The aims of this study were to analyse body composition, to detect the presence of undernutrition, and to establish a relationship between undernutrition and the biological markers routinely used as indicators of nutritional status in hemodialysis (HD) patients (pts). We used a body composition monitor (BCM) that expresses body weight in terms of lean tissue mass (LTM) and fat tissue mass (FTM) independent of hydration status. From nine HD units, 934 pts were included. Undernutrition was defined as having a lean tissue index (LTI = LTM/height2) below the 10th percentile of a reference population. Biochemical markers and parameters delivered by BCM were used to compare low LTI and normal LTI groups. Undernutrition prevalence was 58.8% of the population studied. Low LTI pts were older, were significantly more frequently overhydrated, and had been on HD for a longer period of time than the normal LTI group. FTI (FTI = FTM/ height2) was significantly higher in low LTI pts and increased according to BMI. LTI was not influenced by different BMI levels. Albumin and C-reactive protein correlated inversely (r = −0.28). However neither of them was statistically different when considering undernourished and normal LTI pts. Our BCM study was able to show a high prevalence of undernutrition, as expressed by low LTI. In our study, BMI and other common markers, such as albumin, failed to predict malnutrition as determined by BCM. PMID:27347538

  10. Cardiorespiratory Fitness and Body Composition in Postmenopausal Women

    PubMed Central

    Moreira, Helena; Passos, Betânia; Rocha, Josiane; Reis, Vivianne; Carneiro, André; Gabriel, Ronaldo

    2014-01-01

    The object of the study was to analyze the relationship between aerobic fitness and body composition in postmenopausal women. We hypothesized that postmenopausal women that had higher adiposity had lower cardiorespiratory capacity, regardless of the characteristics of menopause. The sample included 208 women (57.57 ± 6.62 years), whose body composition and the basal metabolic rate were evaluated by octopolar bioimpedance (InBody 720) and the oxygen uptake by the modified Bruce protocol. Most of the sample showed obesity and a high visceral fat area. The visceral fat area and the basal metabolic rate explained 30% of the variation of oxygen uptake, regardless of age, time, nature or hormone therapy. The values of the latter variables were reduced in the presence of high central adiposity (−6.16 ml/kg/min) and the basal metabolic rate of less than 1238 kcal/day (−0.18 ml/kg/min). The women with oxygen uptake above 30.94 ml/kg/min showed lower values of total and central adiposity when compared with other groups. With an increase of aerobic fitness, there was a growing tendency of the average values of the soft lean mass index, with differences between the groups low-high and moderate-high. These results suggest worsening of the cardiorespiratory condition with an increase of central adiposity and a decrease of the BMR, regardless of age and menopause characteristics. PMID:25713654

  11. Body composition and physiological characteristics of law enforcement officers.

    PubMed

    Spitler, D L; Jones, G; Hawkins, J; Dudka, L

    1987-12-01

    The physical work capacity, body composition, and physiological characteristics of 12 law enforcement officers (9 males, 3 females) were measured. Subjects included a representative sample from the occupational categories of detective, staff, investigative and patrol officer. Mean maximal oxygen uptake of the men was 42.1 +/- 8.9 ml.kg-1min-1 with mean values of 41.5 +/- 8.7 ml.kg-1min-1 for the women. Measurement of body composition indicated an average of 24.4 +/- 7.1% body fat for the men and 30.9 +/- 1.2% for the women. Muscular power, strength, and endurance as measured by isolated limb flexion-extension movement and fitness test performance was considered average with no excessive bilateral differences. The results of this study were compared with other investigations of law enforcement officers of similar age groups. The officers displayed average or above health and physical fitness scores for their age classification and were able to complete all police task-oriented tests.

  12. Measurement and Predition Errors in Body Composition Assessment and the Search for the Perfect Prediction Equation.

    ERIC Educational Resources Information Center

    Katch, Frank I.; Katch, Victor L.

    1980-01-01

    Sources of error in body composition assessment by laboratory and field methods can be found in hydrostatic weighing, residual air volume, skinfolds, and circumferences. Statistical analysis can and should be used in the measurement of body composition. (CJ)

  13. Efficiency of energy utilization: effects of diet composition on body composition and mammary neoplasia

    SciTech Connect

    Boissonneault, G.A.; Elson, C.E.; Pariza, M.W.

    1986-03-05

    Multiple interactions between the efficiency of utilization of dietary fat and carbohydrate energy, energy intake changes in body composition and 7,12-dimethylbenz(a)anthracene (DMBA) DMBA-induced mammary tumorigenesis were examined using female F-344 rats. The rats were fed ad libitum a semipurified diet containing 5% corn oil (LF) from weaning to 50 d of age at which each was given, by gavage, 65 mg DMBA/kg body weight. The rats were randomly assigned to diets containing 5% 17.5% (MF) and 30% (HF) corn oil. All diets were balanced with respect per unit of energy in terms of protein, vitamins, minerals and fiber. For 28 d post-DMBA, the rats were fed 40 or 42 kcal daily and thereafter, diet was provided ad libitium. Daily energy intakes were recorded throughout the study. The mean energy intakes during the first 35 wk were: LF, 240 +/- 12.3 kcal/wk; MF, 237 +/- 11.7 kcal/wk; and HF, 237 +/- 11.1 kcal/wk. Body weight at 35 wk were: LF, 196 +/- 9.5 g; MF, 206 +/- 13.9 g; and HF, 210 +/- 20.6 g. No differences in tumor incidence (LF, 55%; MF, 46%; HF, 51%), tumors/group (LF, 24; MF, 28; HF, 25) and tumors/tumor-bearing rat (LF, 1.3 +/- 0.7; MF 1.6 +/- 1.0;p HF, 1.2 +/- 0.4) were noted. Within dietary groups tumor incidence was positively correlated with energy intake. However, there were no differences among the various parameters between dietary groups at any energy intake level. Body compositions were monitored during this study. The body fat mass and % carcass weight increased in parallel with the % dietary fat. Concomitantly, % lean body and, to a lesser extent lean body mass decreased. Both body size and body composition, influenced by energy intake and retention, affected the response to DMBA.

  14. Anthropometric and body composition changes during expeditions at high altitude.

    PubMed

    Zaccagni, Luciana; Barbieri, Davide; Cogo, Annalisa; Gualdi-Russo, Emanuela

    2014-06-01

    The purpose of this study is to investigate separately in the two sexes the physical adaptations associated to exposure to high altitude in a sample of 18 nonacclimatized Caucasian subjects (10 males and 8 females, 22-59 years) who participated to scientific expeditions to Himalaya up to the Pyramid Laboratory (5050 m, Nepal) or Everest North Base Camp (5300 m, Tibet). Anthropometric traits (body height and weight, eight girths and six skinfolds) were collected according to standard procedures, before departure at sea level, during ascent (at altitude > 4000 m above sea level), and after return to low altitude. Body composition was assessed by means of the skinfold method. Both sexes lost on average 4.0% of initial body mass, corresponding to 7.6% of fat mass and 3.5% of fat free mass in males, and to 5.0% of fat mass and 3.6% of fat free mass in females. Average fat mass loss was greater in males than in females. Initial fat mass percentage was positively correlated to fat mass loss and negatively to FFM loss in males only, thus at HA leanest subjects lost more FFM and less FM than the fattest ones. Adaptations were faster in males than in females. In conclusion, the present research describes significant adaptations to high altitude, in terms of body weight reduction, regardless of the amount of performed physical activity. PMID:24665979

  15. Body weight and composition dynamics of fall migrating canvasbacks

    USGS Publications Warehouse

    Serie, J.R.; Sharp, D.E.

    1989-01-01

    We studied body weights and composition of canvasbacks (Aythya valisineria) during fall migration 1975-77 on stopover sites along the upper Mississippi River near La Crosse, Wisconsin (Navigational Pools 7 and 8) and Keokuk, Iowa (Navigational Pool 19). Body weights varied (P < 0.001) by age and sex without interaction. Weights varied by year (P < 0.001) on Pools 7 and 8. Mean weights increased (P < 0.01) within age and sex classes by date and averaged 3.6 and 2.7 g daily on Pools 7 and 8 and Pool 19, respectively. Percent fat was highly correlated (P < 0.001) with carcass weight for each age and sex. Live weight was a good predictor of total body fat. Mean estimated total body fat ranged from 200 to 300 g and comprised 15-20% of live weights among age and sex classes. Temporal weight patterns were less variable for adults than immatures, but generally increased during migration. Length of stopover varied inversely with fat reserves among color-marked adult males. Variation in fat condition of canvasbacks during fall may explain the mechanism regulating population ingress and egress on stopover sites. Fat reserves attained by canvasbacks during fall stopover may have adaptive significance in improving survival by conditioning for winter.

  16. Longitudinal body composition of children born to normal weight, overweight and obese mothers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: The longitudinal trajectories of body composition of children born to normal weight, overweight and obese mothers have not been evaluated using precise body composition methods. This study investigated the relationship between maternal pre-pregnancy BMI and offspring body composition traj...

  17. Foreign body impact event damage formation in composite structures

    NASA Technical Reports Server (NTRS)

    Bucinell, Ronald B.

    1994-01-01

    This report discusses a methodology that can be used to assess the effect of foreign body impacts on composite structural integrity. The described effort focuses on modeling the effect of a central impact on a 5 3/4 inch filament wound test article. The discussion will commence with details of the material modeling that was used to establish the input properties for the analytical model. This discussion is followed by an overview of the impact assessment methodology. The progress on this effort to date is reviewed along with a discussion of tasks that have yet to be completed.

  18. The Effects of Different Exercise Programmes on Female Body Composition

    PubMed Central

    de Mendonça, Rosa Maria Soares Costa; de Araújo Júnior, Adenilson Targino; de Sousa, Maria do Socorro Cirilo; Fernandes, Helder Miguel

    2014-01-01

    The purpose of this study was to verify the effects of 16 weeks of practicing different exercise programmes on body composition. This is an exploratory and descriptive study of 89 women aged 25 to 55 years (41.42 ± 9.23 years). The subjects were randomly divided into three experimental groups (EG): practitioners of strength training (SG), dance (DG), hydrogymnastics (HG), and a control group (CG) with sedentary women. Measurements of body mass and height, circumferences of the chest, waist, abdomen, hips, thighs, calves, and skinfolds of the triceps, suprailiac and thigh were registered in three different moments: prior to the commencement of the training program, again after 8 weeks of training, and finally after 16 weeks of training. Body density was estimated by using the trifold protocol by Jackson, Pollock and Ward. The ANOVA and deltas of change (Δ%) were used for data analysis. The level of significance was set at p<0.05. The effects of greater statistical significance on body composition related the variables “time”, “group” and the interaction between the two (time × group) were observed for the percentage of fat - F% (F (1.79, 152.52) = 24.59, p <0.001, η 2 = 0.22), fat mass - FM (F (1.75, 149.01) = 12.65, p <0.001, η 2 = 0.13) and lean mass - LM (F (1.77, 150.66) = 47.38, p <0.001, η 2 = 0.36). The HG and SG were more beneficial in reducing F%. It was observed that the EG indicated healthier anthropometric aspects compared to the CG, regardless of the type of exercise programmes practiced. The time factor was more representative over the effects of exercise on anthropometric dimensions. PMID:25713646

  19. Determination of body composition in growing rats by total body electrical conductivity.

    PubMed

    Morbach, C A; Brans, Y W

    1992-04-01

    Total body electrical conductivity (TOBEC), measured with an Em-Scan SA-1 analyzer, was evaluated as a means of estimating fat-free mass and total body water content noninvasively in small laboratory animals. Ninety-four rats whose weight ranged from 5.53 to 170.84 g at 0-50 days of age were studied. The animals were killed by intraperitoneal injection of a pentobarbital overdose. After weight, crown-rump length (CRL) and TOBEC were measured, and the animals were minced with scissors and desiccated to constant weight in a convection oven. Fat was extracted by multiple bathings in petroleum ether followed by Soxhlet extraction. Fifty-four rats were used to determine the relation between fat-free mass (FFM), total body water (TBW), and TOBEC# (E) by regression analysis. The best correlations were observed between FFM and (E x CRL)1/2 (r = 0.995, p less than 0.0001). Forty rats were used to determine the predictive value of TOBEC estimates. With this instrument, TOBEC tended to underestimate FFM by an average of 3.9% and TBW by 5.3%. Accuracy was questionable for animals smaller than 13 g and TOBEC did not provide useful estimates of total body fat. Subject to these limitations, TOBEC instruments should prove to be useful for sequential in vivo estimations of body composition during growth and development of small animals.

  20. Effect of particle size and percentages of Boron carbide on the thermal neutron radiation shielding properties of HDPE/B4C composite: Experimental and simulation studies

    NASA Astrophysics Data System (ADS)

    Soltani, Zahra; Beigzadeh, Amirmohammad; Ziaie, Farhood; Asadi, Eskandar

    2016-10-01

    In this paper the effects of particle size and weight percentage of the reinforcement phase on the absorption ability of thermal neutron by HDPE/B4C composites were investigated by means of Monte-Carlo simulation method using MCNP code and experimental studies. The composite samples were prepared using the HDPE filled with different weight percentages of Boron carbide powder in the form of micro and nano particles. Micro and nano composite were prepared under the similar mixing and moulding processes. The samples were subjected to thermal neutron radiation. Neutron shielding efficiency in terms of the neutron transmission fractions of the composite samples were investigated and compared with simulation results. According to the simulation results, the particle size of the radiation shielding material has an important role on the shielding efficiency. By decreasing the particle size of shielding material in each weight percentages of the reinforcement phase, better radiation shielding properties were obtained. It seems that, decreasing the particle size and homogeneous distribution of nano forms of B4C particles, cause to increase the collision probability between the incident thermal neutron and the shielding material which consequently improve the radiation shielding properties. So, this result, propose the feasibility of nano composite as shielding material to have a high performance shielding characteristic, low weight and low thick shielding along with economical benefit.

  1. Reference values for body proportions and body composition in adult women with Ullrich-Turner syndrome.

    PubMed

    Gravholt, C H; Weis Naeraa, R

    1997-11-12

    This cross sectional study was undertaken to establish reference values for adult women with Ullrich-Turner syndrome (UTS) verified cytogenetically by blood karyotyping and not treated with growth hormone during childhood and adolescence, with respect to anthropometric and body composition measurements, for future evaluations of growth promoting therapy. All members of the Danish Turner Association were invited, and 79 women with UTS participated. Forty-two had the 45,X karyotype and the other 37 had different karyotypes. Outcome measures were height, sitting height, arm span, length of hand and foot, biacromial and biiliac diameter, and hip, waist, and head circumference. Bioelectrical impedance was performed, and total body water, lean body mass, and fat mass were calculated. Results give a very distinct anthropometric picture of adult women with the UTS, with a mean height of 146.8+/-6.7 cm (mean+/-SD), sitting height of 78.6+/-3.6 cm, arm span measurements of 147.9+/-7.1 cm, being between 3 and 4 standard deviation scores (SDS) below average; with a mean hand length of 17.0+/-1.1 cm and foot length of 22.4+/-1.2 cm, being around 1.5 SDS below average; a mean weight of 56.3+/-12.8 kg, head circumference of 55.3+/-2.0 cm and biacromial diameter of 36.5+/-2.0 cm, being around 0 SDS; and finally, biiliacal diameter of 29.5+/-2.2 cm, being 1.4 SDS above average. The average body mass index (BMI) in the study was 26.3+/-5.3 kg/m2. As a group, females with UTS are overweight when compared with a group of "normal" women, with a higher fat mass, a lower lean body mass, but with a comparable amount of total body water (in %). This study presents the first comprehensive reference data on body proportions in the adult UTS. It shows that adult women with the Ullrich-Turner syndrome has a characteristic anthropometric shape. The data should be of use for future evaluations of growth hormone treatment or other growth promoting therapy in the UTS on anthropometric and body

  2. A modeling approach for compounds affecting body composition.

    PubMed

    Gennemark, Peter; Jansson-Löfmark, Rasmus; Hyberg, Gina; Wigstrand, Maria; Kakol-Palm, Dorota; Håkansson, Pernilla; Hovdal, Daniel; Brodin, Peter; Fritsch-Fredin, Maria; Antonsson, Madeleine; Ploj, Karolina; Gabrielsson, Johan

    2013-12-01

    Body composition and body mass are pivotal clinical endpoints in studies of welfare diseases. We present a combined effort of established and new mathematical models based on rigorous monitoring of energy intake (EI) and body mass in mice. Specifically, we parameterize a mechanistic turnover model based on the law of energy conservation coupled to a drug mechanism model. Key model variables are fat-free mass (FFM) and fat mass (FM), governed by EI and energy expenditure (EE). An empirical Forbes curve relating FFM to FM was derived experimentally for female C57BL/6 mice. The Forbes curve differs from a previously reported curve for male C57BL/6 mice, and we thoroughly analyse how the choice of Forbes curve impacts model predictions. The drug mechanism function acts on EI or EE, or both. Drug mechanism parameters (two to three parameters) and system parameters (up to six free parameters) could be estimated with good precision (coefficients of variation typically <20 % and not greater than 40 % in our analyses). Model simulations were done to predict the EE and FM change at different drug provocations in mice. In addition, we simulated body mass and FM changes at different drug provocations using a similar model for man. Surprisingly, model simulations indicate that an increase in EI (e.g. 10 %) was more efficient than an equal lowering of EI. Also, the relative change in body mass and FM is greater in man than in mouse at the same relative change in either EI or EE. We acknowledge that this assumes the same drug mechanism impact across the two species. A set of recommendations regarding the Forbes curve, vehicle control groups, dual action on EI and loss, and translational aspects are discussed. This quantitative approach significantly improves data interpretation, disease system understanding, safety assessment and translation across species.

  3. [Blood serum concentration of lipids and lipoproteins and body composition].

    PubMed

    Kozlov, A I; Vershubskaia, G G; Sanina, E D; Ateeva, Iu A; Potolitsina, N N; Kaneva, A M; Rogachevskaia, O V; Boĭko, E P

    2012-01-01

    The purpose of this study is the analysis of the relationship of blood serum apolipoprotein E (apoE), total cholesterol (TC), triglycerides (TG) and high-density and low-density lipoproteins (HDL, LDL), with body mass index (BMI), relative body surface area (RBSA) and body muscle (BM) and body fat (BF). The subjects are males and females aged 14-16 (adolescent age group 1: n1M = 141, n1F = 151) and 18-25 (young adult group 2, n2M = 16, n2F = 46). Significant correlations of serum TG and HDL with somatometric indicators were not observed. In the female samples, TC content directly correlates (p < 0.05) with BF (r1 = 0.164; r2 = 0.418) and negatively correlates with BM (r1 = -0.165; r2 = -0.352). The blood serum concentration of apoE is significantly correlated with body composition in adolescent females (for BF r1 = -0.168; for BM r1 = 0.266; p < 0.05); in males 14-16 years old, the both correlations have a significance level p < 0.06. In young adult females TC and LDL content negatively correlates with RBSA (r2 = -0.386 and -0.377 respectively; p < 0.05) and positively correlates with BMI (r2 = 0.413 and 0.415 respectively; p < 0.05). Adolescent females and young adult females have opposite relationships between FC and apoE concentration. In females 14-15 years old apoE concentration decreases as FC increases. In females 16-17 the correlation disappears, and in older females apoE concentration and FC increase together. PMID:22830251

  4. Dynamic body weight and body composition changes in response to subordination stress

    PubMed Central

    Tamashiro, Kellie L. K.; Hegeman, Maria A.; Nguyen, Mary M. N.; Melhorn, Susan J.; Ma, Li Yun; Woods, Stephen C.; Sakai, Randall R.

    2007-01-01

    Social stress is prevalent in many facets of modern society. Epidemiological data suggest that stress is linked to the development of overweight, obesity and metabolic disease. Although there are strong associations between the incidence of obesity with stress and elevated levels of hormones such as cortisol, there are limited animal models to allow investigation of the etiology of increased adiposity resulting from exposure to stress. Perhaps more importantly, an animal model that mirrors the consequences of stress in humans will provide a vehicle to develop rational clinical therapy to treat or prevent adverse outcomes from exposure to chronic social stress. In the visible burrow system (VBS) model of chronic social stress mixed gender colonies are housed for 2 week periods during which male rats of the colony quickly develop a dominance hierarchy. We found that social stress has significant effects on body weight and body composition such that subordinate rats progressively develop characteristics of obesity that occurs, in part, through neuroendocrine alterations and changes in food intake amount. Although SUB are hyperphagic following social stress they do not increase their intake of sucrose solution as CON and DOM do suggesting that they are anhedonic. Consumption of a high fat diet does not appear to affect development of a social hierarchy and appears to enhance the effect that chronic stress has on body composition. The visible burrow system (VBS) model of social stress may be a potential laboratory model for studying stress-associated metabolic disease, including the metabolic syndrome. PMID:17512562

  5. Effects of exercise modality on metabolic rate and body composition.

    PubMed

    Sale, J E; McCargar, L J; Crawford, S M; Taunton, J E

    1995-01-01

    This study was designed to investigate the effects of exercise as a strategy for weight management in overweight women. Specifically, the effects of exercise modality on resting energy expenditure (REE) and body composition [sum of skinfolds and fat-free mass (FFM)] were examined. Participants included 41 overweight, sedentary women aged 25-49 years who had a defined history of dieting. Experimental (n = 26) and control (n = 15) participants were recruited separately. Participants in the experimental group were randomly assigned to either an endurance- or a resistance-training exercise class. Exercise classes designed for a sedentary population were scheduled three times per week for a duration of 3 months. Results indicated that exercise modality had no effect on REE. Exercise, regardless of modality, had a significant effect on body composition (p = 0.0001) as shown by a significant decrease in the sum of skinfolds for the two exercise groups relative to the control group (p < 0.0001). No differences in fat-free mass were observed between groups. Regardless of modality, exercise also resulted in an increased estimated maximum oxygen uptake (VO2max), based on a 1-mile walking test (p = 0.012). The pattern of weight change of the groups was different (p = 0.029) over the 3-month period. Whereas the exercise groups maintained their weight, the control group gained weight (approximately 2.5 kg). Thus, although exercise modality had no effect, the benefits of exercise per se, such as decreased body fat, increased fitness level, and weight maintenance, were observed in this population.

  6. Growth and body composition in Brazilian female rhythmic gymnastics athletes.

    PubMed

    Camargo, Cristiane Teixeira Amaral; Gomez-Campos, Rossana Anelice; Cossio-Bolaños, Marco Antonio; Barbeta, Vinicius Justino De Oliveira; Arruda, Miguel; Guerra-Junior, Gil

    2014-01-01

    The aim was to analyse the physical growth and body composition of rhythmic gymnastics athletes relative to their level of somatic maturation. This was a cross-sectional study of 136 athletes on 23 teams from Brazil. Mass, standing height and sitting height were measured. Fat-free and fat masses, body fat percentages and ages of the predicted peak height velocity (PHV) were calculated. The z scores for mass were negative during all ages according to both WHO and Brazilian references, and that for standing height were also negative for all ages according to WHO reference but only until 12 years old according to Brazilian reference. The mean age of the predicted PHV was 12.1 years. The mean mass, standing and sitting heights, body fat percentage, fat-free mass and fat mass increased significantly until 4 to 5 years after the age of the PHV. Menarche was reached in only 26% of these athletes and mean age was 13.2 years. The mass was below the national reference standards, and the standing height was below only for the international reference, but they also had late recovery of mass and standing height during puberty. In conclusion, these athletes had a potential to gain mass and standing height several years after PHV, indicating late maturation. PMID:24936888

  7. Relationship between body composition and blood pressure in Bahraini adolescents.

    PubMed

    Al-Sendi, Aneesa M; Shetty, Prakash; Musaiger, Abdulrahman O; Myatt, Mark

    2003-10-01

    The objective of the present study was to examine the relationship between body composition and blood pressure (BP) in Bahraini adolescents. A sample of 504 Bahraini schoolchildren aged 12-17 years (249 boys and 255 girls) was selected using a multi-stage stratified sampling procedure. BP measurements were performed on the students. Anthropometric data including weight, height, waist circumference (WC), hip circumference, and triceps, subscapular and medial calf skinfold thicknesses were also collected. BMI, percentage body fat, waist:hip (WHR), and subscapular:triceps skinfold ratio were calculated. Mean systolic BP and mean diastolic BP were higher in males than in females. Weight and height in boys and weight only in girls were significantly associated with systolic BP independent of age or percentage fat. Nearly 14 % of the adolescents were classified as having high BP. BMI and percentage body fat were significantly and positively associated with the risk of having high BP in the boys and girls. Adolescents with high WHR or WC, as indicators for central obesity, tended to have higher BP values. The results from the present study indicate that obesity influences the BP of Bahraini adolescents and that simple anthropometric measurements such as WHR and WC are useful in identifying children at risk of developing high BP. These findings together with the known tracking of BP from adolescence into adulthood underline the importance of establishing intervention programmes in order to prevent the development of childhood and adolescent obesity.

  8. Bioengineering approach to non-invasive measurement of body composition.

    PubMed

    Dubin, S; Nissanov, J; Zietz, S; Schrope, B; Naim, A; Morano, R; Hanania, R

    1994-01-01

    Measurement of body fat percentage is essential for medical care and research. The "gold standard" method for humans is underwater weighing, which is clearly inappropriate for infants, sick people and non-human animals. The corresponding criterion method for animals is comminution of the carcass followed by extraction of the fat with a volatile solvent such as ether. Our goal has been to develop a method for body composition (fat percentage) for use in animals and humans which is non-invasive and minimally intrusive, independent of variation in body conformation and fat distribution, and reasonable in cost. In one variant, our approach to this problem has been to move Archimedes' principle "on to dry land." The subject's volume is determined by measuring the differential buoyancy in comfortably breathable light (low density) and heavy atmospheres. In another, we use "structured light," in which a pattern of illumination is cast on the patient. The image is acquired using a video camera and the geometrical spatial coordinates of a large number of points on the surface of the subject are acquired. This permits the computation of the surface area and volume of the subject; which, combined with the weight, determines the fat percentage. PMID:7948641

  9. Gravity, body mass and composition, and metabolic rate

    NASA Technical Reports Server (NTRS)

    Pace, N.; Smith, A. H.

    1984-01-01

    The scale effects of increased gravitational loading by chronic centrifugation on metabolic rate and body composition in metabolically mature mammals were investigated. Individual oxygen consumption rates in groups of 12 each, 8-month-old, hamster, rats, guinea pigs, and rabbits were measured at weekly intervals at 1.0 g, then 2.0 g for 6 weeks. Metabolic rate was increased significantly in all species, and stabilized after 2 weeks at 2.0 g. Statistical analysis of the data revealed that the larger the animal the greater was the increase in mass-specific metabolic rate, or metabolic intensity, over the 1.0 g value for the same animal, with the result that the interspecies allometric scaling relationship between metabolic rate and total body mass is different at 2.0 g compared 10 1.0 g. Analysis of covariance shows that the postioning constant at 2.0 g is increased by 17% at 2.0 g at the P .001 level, and the exponent is increased by 8% at the P = 0.008 level. Thus, the hypothesis that augmented gravitational loading should shift the allometric relationship between metabolic rate and body size by an increase in both parameters is supported.

  10. New way of body composition analysis using total body electrical conductivity method

    NASA Astrophysics Data System (ADS)

    Piasecki, Wojciech; Koteja, Pawel; Weiner, January; Froncisz, Wojciech

    1995-04-01

    Traditional methods of measuring total body water and fat content of animals that require sacrificing specimens are generally unacceptable when endangered species, or large animal sizes, or humans are involved. These methods are also unsuitable for following changes of fat and water content in individuals. An alternative method, based on the nonresonant absorption of a rf electromagnetic field has been used for constructing a new body composition analyzer. As the electrical conductivity of lipids is approximately 20 times lower than that of lean tissues, the rf power absorbed by the animal provides information which enables one to calculate the lean body mass and total body water. The new instrument measures rf power absorbed by an animal by measuring the quality factor (Q) of the resonant circuit with an animal placed inside the coil. Numerical calculations of the rf power absorbed by a cylindrical object containing 0.9% NaCl aqueous solution have also been performed. Experimental values confirmed the calculated dependence of the absorbed power on the cylinder radius. The device built has been calibrated on 9 males and 11 females of laboratory mice. The amount of lipids was then measured by ether extraction. The relation between instrument reading, which is proportional to the power absorption, and lean body mass (LBM) or water mass (WM) was linear and highly significant: the simple regression coefficients of determination were 0.983 for LBM, and 0.990 for WM (p<0.001). It has been found that for an individual animal with a body mass ranging from 15.9 to 40.7 g, the accuracy of measurement was ±1.6 g for LBM and ±1 g for WM.

  11. Effects of whole body vibration training on body composition, skeletal muscle strength, and cardiovascular health

    PubMed Central

    Park, Song-Young; Son, Won-Mok; Kwon, Oh-Sung

    2015-01-01

    Whole body vibration training (WBVT) has been used as a supplement to conventional exercise training such as resistance exercise training to improve skeletal muscle strength, specifically, in rehabilitation field. Recently, this exercise modality has been utilized by cardiovascular studies to examine whether WBVT can be a useful exercise modality to improve cardiovascular health. These studies reported that WBVT has not only beneficial effects on muscular strength but also cardiovascular health in elderly and disease population. However, its mechanism underlying the beneficial effects of WBVT in cardiovascular health has not been well documented. Therefore, this review highlighted the impacts of WBVT on cardiovascular health, and its mechanisms in conjunction with the improved muscular strength and body composition in various populations. PMID:26730378

  12. Temperature Dependence on the Strength and Stress Rupture Behavior of a Carbon-Fiber Reinforced Silicon Carbide (C/SiC) Composite

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.; Calomino, Anthony

    2002-01-01

    Tensile strengths and stress rupture lives of carbon-fiber reinforced silicon carbide (C/SiC) specimens were measured at 800 C and are compared to previously reported 1200 C data. All tests were conducted in an environmental chamber containing 1000 ppm of oxygen in argon. The average 800 C tensile strength of 610 MPa is 10% greater than at 1200 C. Average stress rupture lives at 800 C were 2.5 times longer than those obtained at 1200 C. The difference in the 800 and 1200 C lives is related to the oxidation rate of the reinforcing carbon fibers, which is the primary damage mode of C/SiC composites in oxygen-containing environments.

  13. Body Composition and Pulmonary Function in Cystic Fibrosis

    PubMed Central

    Sheikh, Saba; Zemel, Babette S.; Stallings, Virginia A.; Rubenstein, Ronald C.; Kelly, Andrea

    2014-01-01

    Background: Lower body mass index (BMI) is associated with worse pulmonary function in cystic fibrosis (CF). Hypothesis: lean body mass (LBM) is more strongly associated with pulmonary function than BMI is. Methods: Anthropometrics, body composition by dual x-ray absorptiometry, and pulmonary function were determined in pancreatic insufficient CF (PI-CF) youth. Sex and age-adjusted Z-scores (BMI-Z, LBMI-Z, FMI-Z) were generated for CF and controls. (1) Associations of BMI-Z with LBMI-Z and FMI-Z and (2) age-adjusted associations of BMI-Z, LBMI-Z, and FMI-Z with FEV1%-predicted were tested. Results: Two hundred eight PI-CF subjects had lower BMI-Z, LBMI-Z, and FMI-Z compared to 390 controls. BMI-Z was associated with lower LBMI-Z (p < 0.0001) in PI-CF. In females, LBMI-Z and BMI-Z were positively associated with FEV1%-predicted; this relationship did not persist for FMI-Z after adjustment for LBMI-Z. In males, only LBMI-Z and BMI-Z were associated with FEV1%-predicted. Conclusion: In PI-CF youth, deficits in LBM were apparent. At lower BMI percentiles, BMI may not accurately depict LBM in PI-CF. In under-nourished PI-CF youth, this preservation of FM in preference to LBM is relevant since LBMI-Z, but not FMI-Z, is positively associated with FEV1%-predicted. Lean body mass index is more strongly associated with lung function compared to BMI, especially in the under-nourished child and adolescent with PI-CF. PMID:24783186

  14. Temperature control of thermal radiation from composite bodies

    NASA Astrophysics Data System (ADS)

    Jin, Weiliang; Polimeridis, Athanasios G.; Rodriguez, Alejandro W.

    2016-03-01

    We demonstrate that recent advances in nanoscale thermal transport and temperature manipulation can be brought to bear on the problem of tailoring thermal radiation from wavelength-scale composite bodies. We show that such objects—complicated arrangements of phase-change chalcogenide (Ge2Sb2Te5 ) glasses and metals or semiconductors—can be designed to exhibit strong resonances and large temperature gradients, which in turn lead to large and highly directional emission at midinfrared wavelengths. We find that partial directivity depends sensitively on a complicated interplay between shape, material dispersion, and temperature localization within the objects, requiring simultaneous design of the electromagnetic scattering and thermal properties of these structures. Our calculations exploit a recently developed fluctuating-volume current formulation of electromagnetic fluctuations that rigorously captures radiation phenomena in structures with strong temperature and dielectric inhomogeneities, such as those studied here.

  15. Redefining body composition: nutrients hormones, and genes in meat production.

    PubMed

    Wray-Cahen, C D; Kerr, D E; Evock-Clover, C M; Steele, N C

    1998-01-01

    Growth rate and body composition of livestock can be optimized to meet consumer needs for a leaner product and to improve the efficiency of meat-animal production. Optimization strategies have traditionally focused on genetic selection and cost-effective ration formulation to achieve the genetic potential. Advances in understanding the mechanisms of growth and its control have led to additional opportunities for its manipulation. These include nutritional manipulation,the use of growth promotants, and, more recently, the ability to change the genetic potential through genetic engineering. Selection of appropriate candidate genes for manipulation depends on understanding the mechanisms underlying differentiation and growth of embryonic muscle cells. Recent advances in genetic engineering techniques, including gene therapy and germline transgenesis, will likely hasten the genetic progress toward a leaner carcass in domestic livestock. Such strategies may prove to be more beneficial then the controlled enhancement of somatotropin expression.

  16. The elite athlete - assessing body shape, size, proportion and composition.

    PubMed

    Kerr, D A; Ackland, T R; Schreiner, A B

    1995-03-01

    In the quest to optimize performance of the elite athlete the sport scientist has sought to determine the ideal physique for a given sport or event. For some sports, specific structural characteristics offer definite performance advantages; for example in rowing, in addition to height, a large arm span has been identified as important. In other sports. such as long distance running, low levels of adiposity or 'fatness' appear to be linked with faster running times. There are four areas where appraisal of the athlete's physique can provide useful information: (1) identification of talented athletes; (2) to assess and monitor the growing athlete; (3) to monitor training and performance; and (4) to determine 'race weight' in weight-category sports. As a research tool a particular method must be reliable and valid. Other considerations include how expensive the method is, if it is suitable for a field situation and if large amounts of data on a number of subjects can be collected quickly. The method should be safe for both the athlete and the tester and provide useful feedback for the athlete or coach. Anthropometry, with training is able to fulfil most of these criteria and is the most widely used method of physique assessment in sports science. Large anthropometric data bases have been collected on elite athletes at Olympic games and world championships according to a standard protocol. Kinanthropometry, which has developed from anthropometry, is concerned with measurement and evaluation of different aspects of human movement and individual variation in body shape, size, proportion and composition. For the assessment of adiposity a sum of skinfolds, usually over six sites, is most commonly used rather than percentage body fat formulae. Muscle mass can be assessed indirectly through girth and corrected girth measurements. Limb lengths and breadths are used to assess skeletal structure and proportional differences in limb size. The anthropometric methods most commonly

  17. Silicon carbide sewing thread

    NASA Technical Reports Server (NTRS)

    Sawko, Paul M. (Inventor)

    1995-01-01

    Composite flexible multilayer insulation systems (MLI) were evaluated for thermal performance and compared with currently used fibrous silica (baseline) insulation system. The systems described are multilayer insulations consisting of alternating layers of metal foil and scrim ceramic cloth or vacuum metallized polymeric films quilted together using ceramic thread. A silicon carbide thread for use in the quilting and the method of making it are also described. These systems provide lightweight thermal insulation for a variety of uses, particularly on the surface of aerospace vehicles subject to very high temperatures during flight.

  18. Whole body and regional body composition changes following 10-day hypoxic confinement and unloading-inactivity.

    PubMed

    Debevec, Tadej; McDonnell, Adam C; Macdonald, Ian A; Eiken, Ola; Mekjavic, Igor B

    2014-03-01

    Future planetary habitats will expose inhabitants to both reduced gravity and hypoxia. This study investigated the effects of short-term unloading and normobaric hypoxia on whole body and regional body composition (BC). Eleven healthy, recreationally active, male participants with a mean (SD) age of 24 (2) years and body mass index of 22.4 (3.2) kg·m(-2) completed the following 3 10-day campaigns in a randomised, cross-over designed protocol: (i) hypoxic ambulatory confinement (HAMB; FIO2 = 0.147 (0.008); PIO2 = 93.8 (0.9) mm Hg), (ii) hypoxic bed rest (HBR; FIO2 = 0.147 (0.008); PIO2 = 93.8 (0.9) mm Hg), and (iii) normoxic bed rest (NBR; FIO2 = 0.209; PIO2 = 133.5 (0.7) mm Hg). Nutritional requirements were individually precalculated and the actual intake was monitored throughout the study protocol. Body mass, whole body, and regional BC were assessed before and after the campaigns using dual-energy X-ray absorptiometry. The calculated daily targeted energy intake values were 2071 (170) kcal for HBR and NBR and 2417 (200) kcal for HAMB. In both HBR and NBR campaigns the actual energy intake was within the targeted level, whereas in the HAMB the intake was lower than targeted (-8%, p < 0.05). Body mass significantly decreased in all 3 campaigns (-2.1%, -2.8%, and -2.0% for HAMB, HBR, and NBR, respectively; p < 0.05), secondary to a significant decrease in lean mass (-3.8%, -3.8%, -4.3% for HAMB, HBR, and NBR, respectively; p < 0.05) along with a slight, albeit not significant, increase in fat mass. The same trend was observed in the regional BC regardless of the region and the campaign. These results demonstrate that, hypoxia per se, does not seem to alter whole body and regional BC during short-term bed rest. PMID:24552383

  19. Abdominal body composition differences in NFL football players.

    PubMed

    Bosch, Tyler A; Burruss, T Pepper; Weir, Nate L; Fielding, Kurt A; Engel, Bryan E; Weston, Todd D; Dengel, Donald R

    2014-12-01

    The purpose of this study was to examine visceral fat mass as well as other measures abdominal body composition in National Football League (NFL) players before the start of the season. Three hundred and seventy NFL football players were measured before the start of the season using dual-energy x-ray absorptiometry. Regional fat and lean mass was measured for each player. Players were categorized into 3 groups based on positions that mirror each other: linemen; linebackers/tight ends/running backs and wide receivers/defensive backs. Significant differences were observed between the position groups for both lean and fat regional measurements. However, the magnitude of difference was much greater for fat measures than lean measures. Additionally, a threshold was observed (∼114 kg) at which there is a greater increase in fat accumulation than lean mass accumulation. The increase in fat accumulation is distributed to the abdominal region where thresholds were observed for subcutaneous abdominal fat accumulation (12.1% body fat) and visceral abdominal fat accumulation (20.1% body fat), which likely explains the regional fat differences between groups. The results of this study suggest that as players get larger, there is more total fat than total lean mass accumulation and more fat is distributed to the abdominal region. This is of importance as increased fat mass may be detrimental to performance at certain positions. The thresholds observed for increased abdominal fat accumulation should be monitored closely given recent research observed that abdominal obesity predicts lower extremity injury risk and visceral adipose tissue's established association with cardiometabolic risk.

  20. Effect of surfactant concentration in the electrolyte on the tribological properties of nickel-tungsten carbide composite coatings produced by pulse electro co-deposition

    NASA Astrophysics Data System (ADS)

    Kartal, Muhammet; Uysal, Mehmet; Gul, Harun; Alp, Ahmet; Akbulut, Hatem

    2015-11-01

    A nickel plating bath containing WC particles was used to obtain hard and wear-resistant particle reinforced Ni/WC MMCs on steel surfaces for anti-wear applications. Copper substrates were used for electro co-deposition of Ni matrix/WC with the particle size of <1 μm tungsten carbide reinforcements. The influence of surfactant (sodium dodecyl sulfate, SDS) concentration on particle distribution, microhardness and wear resistance of composite coatings has been studied. The nickel films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of the surfactant on the zeta potential, co-deposition and distribution of WC particles in the nickel matrix, as well as the tribological properties of composite coatings were also investigated. The tribological behaviors of the electrodeposited WC composite coatings sliding against M50 steel ball (Ø 10 mm) were examined on a CSM Instrument. All friction and wear tests were performed without lubrication at room temperature and in the ambient air (relative humidity 55-65%).

  1. School-Based BMI and Body Composition Screening and Parent Notification in California: Methods and Messages

    ERIC Educational Resources Information Center

    Madsen, Kristine A.; Linchey, Jennifer

    2012-01-01

    Background: School-based body mass index (BMI) or body composition screening is increasing, but little is known about the process of parent notification. Since 2001, California has required annual screening of body composition via the FITNESSGRAM, with optional notification. This study sought to identify the prevalence of parental notification…

  2. Sedentary Activity and Body Composition of Middle School Girls: The Trial of Activity for Adolescent Girls

    ERIC Educational Resources Information Center

    Pratt, Charlotte; Webber, Larry S.; Baggett, Chris D.; Ward, Dianne; Pate, Russell R.; Murray, David; Lohman, Timothy; Lytle, Leslie; Elder, John P.

    2008-01-01

    This study describes the relationships between sedentary activity and body composition in 1,458 sixth-grade girls from 36 middle schools across the United States. Multivariate associations between sedentary activity and body composition were examined with regression analyses using general linear mixed models. Mean age, body mass index, and…

  3. Thermal conductivity of boron carbides

    NASA Technical Reports Server (NTRS)

    Wood, C.; Emin, D.; Gray, P. E.

    1985-01-01

    Knowledge of the thermal conductivity of boron carbide is necessary to evaluate its potential for high-temperature thermoelectric energy conversion applications. Measurements have been conducted of the thermal diffusivity of hot-pressed boron carbide BxC samples as a function of composition (x in the range from 4 to 9), temperature (300-1700 K), and temperature cycling. These data, in concert with density and specific-heat data, yield the thermal conductivities of these materials. The results are discussed in terms of a structural model that has been previously advanced to explain the electronic transport data. Some novel mechanisms for thermal conduction are briefly discussed.

  4. Aqueous Alteration and Hydrogen Generation on Parent Bodies of Unequilibrated Ordinary Chondrites: Thermodynamic Modeling for the Semarkona Composition

    NASA Technical Reports Server (NTRS)

    Zolotov, M. Y.; Mironenko, M. V.; Shock, E. L.

    2005-01-01

    Ordinary chondrites are the most abundant class of meteorites that could represent rocky parts of solar system bodies. However, even the most primitive unequilibrated ordinary chondrites (UOC) reveal signs of mild alteration that affected the matrix and peripheral zones of chondrules. Major chemical changes include oxidation of kamacite, alteration of glass, removal of alkalis, Al, and Si from chondrules, and formation of phases enriched in halogens, alkalis, and hydrogen. Secondary mineralogical changes include formation of magnetite, ferrous olivine, fayalite, pentlandite, awaruite, smectites, phosphates, carbonates, and carbides. Aqueous alteration is consistent with the oxygen isotope data for magnetite. The presence of secondary magnetite, Ni-rich metal alloys, and ferrous silicates in UOC implies that H2O was the oxidizing agent. However, oxidation by H2O means that H2 is produced in each oxidative pathway. In turn, production of H2, and its redistribution and possible escape should have affected total pressure, as well as the oxidation state of gas, aqueous and mineral phases in the parent body. Here we use equilibrium thermodynamic modeling to explore water-rock reactions in UOC. The chemical composition of gas, aqueous, and mineral phases is considered.

  5. Bone mineral density and body composition of collegiate modern dancers.

    PubMed

    Friesen, Karlie J; Rozenek, Ralph; Clippinger, Karen; Gunter, Kathy; Russo, Albert C; Sklar, Susan E

    2011-03-01

    This study investigates body composition (BC), bone mineral density (BMD), eating behaviors, and menstrual dysfunction in collegiate modern dancers. Thirty-one female collegiate modern dance majors (D), 18 to 25 years of age, and 30 age-matched controls (C) participated in the study. BC and BMD were measured using dual energy x-ray absorptiometry (DXA). Upper and lower body strength was assessed by chest and leg press one-repetition maximum tests. Participants completed three-day food records, and the diet was analyzed using nutritional software. Menstrual dysfunction (MD) and history of eating disorder (ED) data were collected via questionnaires. BC and BMD variables were analyzed using MANCOVA and frequency of ED and MD by Chi-Square analysis. BMD was greater in D than C at the spine (1.302 ± 0.135 g/cm(2) vs. 1.245 ± 0.098 g/cm(2)), and both the right hip (1.163 ± 0.111 g/cm(2) vs. 1.099 ± 0.106 g/cm(2)) and left hip (1.160 ± 0.114 g/cm(2) vs. 1.101 ± 0.104 g/cm(2); p ≤ 0.05). Total body fat percentage was lower in D than C (25.9 ± 4.2% vs. 32.0 ± 5.9%; p ≤ 0.05), and percent of fat distributed in the android region was also lower in D than C (28.0 ± 6.2% vs. 37.6 ± 8.6%; p ≤ 0.05). With regard to diet composition, only percent fat intake was lower in D than C (27.54 ± 6.8% vs. 31.5 ± 7.4%, p ≤ 0.05). A greater incidence of ED was reported by D than C (12.9% vs. 0%; p ≤ 0.05), as well as a greater incidence of secondary amenorrhea (41.9% vs 13.3%; p ≤ 0.05). No differences were found for incidence of primary amenorrhea, oligomenorrhea, or use of birth control. Strength values were higher in D than C for both chest press (30.1 ± 0.9 kg vs. 28.4 ± 1.0 kg; p ≤ 0.05) and leg press (170.7 ± 4.2 kg vs.163.1 ± 3.9 kg; p ≤ 0.05). It is concluded that the dancers in our study had a healthy body weight, yet reported a higher incidence of eating disorders and menstrual dysfunction, than non-dancers. These dancers' higher BMD may be

  6. Comparison of Body Composition Assessment Methods in Pediatric Intestinal Failure

    PubMed Central

    Mehta, Nilesh M.; Raphael, Bram; Guteirrez, Ivan; Quinn, Nicolle; Mitchell, Paul D.; Litman, Heather J.; Jaksic, Tom; Duggan, Christopher P.

    2015-01-01

    Objectives To examine the agreement of multifrequency bioelectric impedance analysis (BIA) and anthropometry with reference methods for body composition assessment in children with intestinal failure (IF). Methods We conducted a prospective pilot study in children 14 years of age or younger with IF resulting from either short bowel syndrome (SBS) or motility disorders. Bland Altman analysis was used to examine the agreement between BIA and deuterium dilution in measuring total body water (TBW) and lean body mass (LBM); and between BIA and dual X-ray absorptiometry (DXA) techniques in measuring LBM and FM. Fat mass (FM) and percent body fat (%BF) measurements by BIA and anthropometry, were also compared in relation to those measured by deuterium dilution. Results Fifteen children with IF, median (IQR) age 7.2 (5.0, 10.0) years, 10 (67%) male, were studied. BIA and deuterium dilution were in good agreement with a mean bias (limits of agreement) of 0.9 (-3.2, 5.0) for TBW (L) and 0.1 (-5.4 to 5.6) for LBM (kg) measurements. The mean bias (limits) for FM (kg) and %BF measurements were 0.4 (-3.8, 4.6) kg and 1.7 (-16.9, 20.3)% respectively. The limits of agreement were within 1 SD of the mean bias in 12/14 (86%) subjects for TBW and LBM, and in 11/14 (79%) for FM and %BF measurements. Mean bias (limits) for LBM (kg) and FM (kg) between BIA and DXA were 1.6 (-3.0 to 6.3) kg and -0.1 (-3.2 to 3.1) kg, respectively. Mean bias (limits) for FM (kg) and %BF between anthropometry and deuterium dilution were 0.2 (-4.2, 4.6) and -0.2 (-19.5 to 19.1), respectively. The limits of agreement were within 1 SD of the mean bias in 10/14 (71%) subjects. Conclusions In children with intestinal failure, TBW and LBM measurements by multifrequency BIA method were in agreement with isotope dilution and DXA methods, with small mean bias. In comparison to deuterium dilution, BIA was comparable to anthropometry for FM and %BF assessments with small mean bias. However, the limits of agreement

  7. Seasonal Changes in Whole Body and Regional Body Composition Profiles of Elite Collegiate Ice-Hockey Players.

    PubMed

    Prokop, Neal W; Reid, Ryan E R; Andersen, Ross E

    2016-03-01

    The monitoring of a collegiate hockey player's body composition can reflect fitness characteristics and may help players, coaches, or strength and conditioning specialists optimize physiologic gains during an off-season, whereas simultaneously preventing performance decrements in-season. The purpose of the study was to investigate changes in whole-body and regional-body composition of fat and lean tissue. The body composition profiles of 19 elite Canadian collegiate hockey players were assessed using dual energy X-ray absorptiometry. Players completed end-of-season, preseason, and midseason assessments with questionnaires relating to their off-season and in-season training. Statistically significant changes in body composition profiles were observed between the different time points because players showed various tissue gains and losses depending on the region assessed. Overall, players gained (1.38 kg, p ≤ 0.01) and lost (0.79 kg, p ≤ 0.01) fat tissue during the off-season and in-season, respectively. Players also showed a significant gain of leg lean tissue (0.29 kg, p = 0.02) and loss of arm tissue mass (-0.25 kg, p = 0.02) during the first-half of the competitive season. Several correlations emerged that may provide insight into potential trends that could be more pronounced during longer and more demanding schedules. Collegiate hockey players show changes in body composition during the off-season and in-season. The understanding of body composition profiles, body composition fluctuations, and potential variables that may influence the composition of collegiate hockey players can help coaches and athletic programs tailor their team's training, nutrition, lifestyle, and informative resources to further support their athletes. PMID:26907839

  8. Seasonal Changes in Whole Body and Regional Body Composition Profiles of Elite Collegiate Ice-Hockey Players.

    PubMed

    Prokop, Neal W; Reid, Ryan E R; Andersen, Ross E

    2016-03-01

    The monitoring of a collegiate hockey player's body composition can reflect fitness characteristics and may help players, coaches, or strength and conditioning specialists optimize physiologic gains during an off-season, whereas simultaneously preventing performance decrements in-season. The purpose of the study was to investigate changes in whole-body and regional-body composition of fat and lean tissue. The body composition profiles of 19 elite Canadian collegiate hockey players were assessed using dual energy X-ray absorptiometry. Players completed end-of-season, preseason, and midseason assessments with questionnaires relating to their off-season and in-season training. Statistically significant changes in body composition profiles were observed between the different time points because players showed various tissue gains and losses depending on the region assessed. Overall, players gained (1.38 kg, p ≤ 0.01) and lost (0.79 kg, p ≤ 0.01) fat tissue during the off-season and in-season, respectively. Players also showed a significant gain of leg lean tissue (0.29 kg, p = 0.02) and loss of arm tissue mass (-0.25 kg, p = 0.02) during the first-half of the competitive season. Several correlations emerged that may provide insight into potential trends that could be more pronounced during longer and more demanding schedules. Collegiate hockey players show changes in body composition during the off-season and in-season. The understanding of body composition profiles, body composition fluctuations, and potential variables that may influence the composition of collegiate hockey players can help coaches and athletic programs tailor their team's training, nutrition, lifestyle, and informative resources to further support their athletes.

  9. Compositions of Oceans on Icy Solar System Bodies (Invited)

    NASA Astrophysics Data System (ADS)

    Zolotov, M. Y.

    2010-12-01

    Interior oceans may exist on at least several solar system bodies: Europa, Enceladus, Ganymede, Titan and Triton. Compositions of the oceans could reflect bulk chemistries on the bodies, degree and timing of differendentition, current temperature and pressure conditions, and chemical exchanges between icy shells, liquid layers, and suboceanic solids (rocks, sediments, ices and clathrates). Observational signs are sparse and modeling is the major approach to evaluate oceanic compositions. On Europa, a presence of S(VI) species and CO2 at endogenic surface features [1] suggests sulfates and C species (organic and/or inorganic) in the ocean. The detection of NaCl and Na2CO3/NaHCO3-bearing grains emitted from Enceladus [2] implies the dominance of Na, Cl and carbonate/bicarbonate ions in the past and/or present alkaline fluids in the interior. These observations are consistent with independent models for water-rock interaction [3]. Evaluated low contents of other elements (Mg, Fe, Ca, K, S, P, etc.) in initial oceanic waters [3] are accounted for by low solubilities of minerals deposited from water solutions (serpentine, saponite, magnetite, carbonates, sulfides and phosphates). Oceanic redox states are affected by the composition of accreted ices and rocks, hydrogen production through oxidation of solids (mainly Fe-Ni metal) by water and an efficiency of H2 escape. Formation of a sulfate-bearing ocean (as on Europa) through oxidation of sulfides could have been driven by radiolytically-formed oxidants (H2O2, O2), high-temperature (>500 K) hydrothermal activity and H2 escape. Formation of sulfate facilitates leaching of Mg from minerals leading to the Mg-SO4-Na-Cl ocean. Although some of these factors could have played roles on the Galilean satellites, formation of sulfate-bearing oceans beyond Jupiter is unlikely. Accretion of cometary-type ices on moons allows an existence of water-methanol-ammonia liquids at ~153 K, although ammonia could have been sequestered in

  10. The association between abdominal body composition and vascular calcification.

    PubMed

    Jensky, Nicole E; Criqui, Michael H; Wright, C Michael; Wassel, Christina L; Alcaraz, John E; Allison, Matthew A

    2011-12-01

    Subclinical cardiovascular disease (CVD) may be associated with both adipose and skeletal muscle tissues in the abdomen. Accordingly, we examined whether subcutaneous, intermuscular, and visceral adipose tissue, as well as abdominal lean muscle, were associated with the presence and extent of vascular calcification in multiple vascular beds. Three hundred and ninety four patients (58.1% men) underwent electron beam computed tomography (EBCT) scans as part of routine health maintenance screening. The coronary and carotid calcium scores were analyzed at the time of the scan, whereas the other calcium scores, as well as the body composition analyses, were analyzed retrospectively. Mean age was 55.2 ± 11.1 years and BMI was 26.9 ± 4.2. The prevalence of any calcification in the carotids, coronaries, thoracic aorta, abdominal aorta, and iliacs was 30.1, 60.1, 39.8, 55.7, and 56.8%, respectively. Compared to those with calcification in different vascular beds, those without vascular calcification generally had significantly more lean muscle and less adipose tissue. In separate multivariable logistic models, a 1 s.d. increment in the ratio of abdominal and visceral fat to total area of each corresponding compartments was significantly associated with an increased odds for the presence of thoracic aortic calcium (odds ratio (OR) = 1.6, 1.5, respectively; P = 0.01 for both). Conversely, increases in abdominal lean muscle were associated with significantly decreased odds of thoracic aortic calcification (OR = 0.34; P ≤ 0.01). A similar pattern of associations existed among the other vascular beds. Also, the association between lean muscle and vascular calcification was independent of visceral adipose tissue. In conclusion, adipose tissue was positively and lean body mass inversely associated with prevalent aortic calcification. PMID:21475146

  11. Evaluation of morphological indices and total body electrical conductivity to assess body composition in big brown bats

    USGS Publications Warehouse

    Pearce, R.D.; O'Shea, T.J.; Wunder, B.A.

    2008-01-01

    Bat researchers have used both morphological indices and total body electric conductivity (TOBEC) as proxies for body condition in a variety of studies, but have typically not validated these indices against direct measurement of body composition. We quantified body composition (total carcass lipids) to determine if morphological indices were useful predictors of body condition in big brown bats (Eptesicus fuscus). We also evaluated body composition indirectly by TOBEC using EM-SCAN?? technology. The most important predictors of body composition in multiple regression analysis were body mass-to-forearm ratio (partial r2 = 0.82, P < 0.001) followed by TOBEC measurement (partial r2 = 0.08, P < 0.001) and to a minor extent head length (partial r2 = 0.02, P < 0.05). Morphological condition indices alone may be adequate for some studies because of lower cost and effort. Marking bats with passive integrated transponder (PIT) tags affected TOBEC measurements. ?? Museum and Institute of Zoology PAS.

  12. Co-precipitated and collocated carbides and Cu-rich precipitates in a Fe-Cu steel characterized by atom-probe tomography.

    PubMed

    Kolli, R Prakash; Seidman, David N

    2014-12-01

    The composition of co-precipitated and collocated NbC carbide precipitates, Fe3C iron carbide (cementite), and Cu-rich precipitates are studied experimentally by atom-probe tomography (APT). The Cu-rich precipitates located at a grain boundary (GB) are also studied. The APT results for the carbides are supplemented with computational thermodynamics predictions of composition at thermodynamic equilibrium. Two types of NbC carbide precipitates are distinguished based on their stoichiometric ratio and size. The Cu-rich precipitates at the periphery of the iron carbide and at the GB are larger than those distributed in the α-Fe (body-centered cubic) matrix, which is attributed to short-circuit diffusion of Cu along the GB. Manganese segregation is not observed at the heterophase interfaces of the Cu-rich precipitates that are located at the periphery of the iron carbide or at the GB, which is unlike those located at the edge of the NbC carbide precipitates or distributed in the α-Fe matrix. This suggests the presence of two populations of NiAl-type (B2 structure) phases at the heterophase interfaces in multicomponent Fe-Cu steels.

  13. Elasticity and inelasticity of biomorphic carbon, silicon carbide, and SiC/Si composite produced on the basis of medium density fiberboard

    NASA Astrophysics Data System (ADS)

    Kardashev, B. K.; Orlova, T. S.; Smirnov, B. I.; de Arellano-Lopez, A. R.; Martinez-Fernandez, J.

    2010-10-01

    The amplitude and temperature dependences of the Young’s modulus and the internal friction (ultrasonic absorption) of biomorphic carbon, silicon carbide, and SiC/Si composite produced from medium density fiberboard (MDF) by pyrolysis (carbonization), followed by infiltration of molten silicon into the prepared carbon preform have been studied in the temperature range 100-293 K in air and under vacuum. The measurements have been performed by the acoustic resonance method with the use of a composite vibrator for longitudinal vibrations at frequencies of approximately 100 kHz. The data obtained by acoustic measurements of the amplitude dependences of the elastic modulus have been used for evaluating the microplastic properties of samples under study. It has been shown that the Young’s modulus, the decrement of elastic vibrations, and the conventional microyield strength of the MDF samples differ from the corresponding data for previously studied similar materials produced from natural eucalyptus, beech, sapele, and pine woods. In particular, the desorption of environmental molecules at small amplitudes of vibrations, which is typical of biomorphic materials based on natural wood, is almost absent for the MDF samples. The results obtained have been explained by different structures and the influence of pores and other defects, which, to a large extent, determine the mechanical characteristics of the biomaterials under investigation.

  14. Materials characterization of silicon carbide reinforced titanium (Ti/SCS-6) metal matrix composites. Part 2: Theoretical modeling of fatigue behavior

    SciTech Connect

    Chiang, K.T.; Loh, D.H.; Liaw, P.K.; Diaz, E.S.

    1995-12-01

    Flexural fatigue behavior was investigated on titanium (Ti-15V-3Cr) metal matrix composites reinforced with cross-ply, continuous silicon carbide (SiC) fibers. The titanium composites had an eight-ply (0, 90, +45, {minus}45 deg) symmetric layup. Mechanistic investigation of the fatigue behavior is presented in Part 1 of this series. In Part 2, theoretical modeling of the fatigue behavior was performed using finite element techniques to predict the four stages of fatigue deflection behavior. On the basis of the mechanistic understanding, the fiber and matrix fracture sequence was simulated from ply to ply in finite element modeling. The predicted fatigue deflection behavior was found to be in good agreement with the experimental results. Furthermore, it has been shown that the matrix crack initiation starts in the 90 deg ply first, which is in agreement with the experimental observation. Under the same loading condition, the stress in the 90 deg ply of the transverse specimen is greater than that of the longitudinal specimen. This trend explains whey the longitudinal specimen has a longer fatigue life than the transverse specimen, as observed in Part 1.

  15. Effects of neutering on food intake, body weight and body composition in growing female kittens.

    PubMed

    Alexander, Lucille G; Salt, Carina; Thomas, Gaelle; Butterwick, Richard

    2011-10-01

    To understand the effects of neutering on food intake, body weight (BW) and body composition in kittens, data from an unrelated study were subjected to post hoc analysis. A total of twelve pairs of 11-week-old female littermates were randomly assigned to either a neutered group (neutered at 19 weeks old) or an entire group (kept entire) and offered free access to a dry diet until the age of 1 year. Neutered kittens exhibited increased food intake and increased BW after neutering (both P < 0.00 001). Food intake (per kg BW) peaked 10 weeks after neutering; the mean intake of neutered kittens was 17 (95 % CI 8, 27) % more than entire littermates (P = 0.00 014). The intake was then reduced until there was no significant difference between the groups 18 weeks post-neutering. By 52 weeks of age, the neutered kittens were 24 (95 % CI 11, 39) % heavier than entire littermates (P < 0.0001) with a body condition score (BCS) 16.6 (95 % CI 0.9, 34.8) % higher (P = 0.0028). Neutered kittens continued to grow significantly fatter after neutering (all P < 0.0014), while entire kittens showed no significant change after 18 weeks of age. As neutered kittens consumed similar amounts of energy to their entire littermates from 18 weeks post-neutering, while their BW, BCS and percentage fat continued to increase, we suggest that neutered kittens have a reduced metabolisable energy requirement, and should therefore be fed to maintain an ideal BCS rather than ad libitum. Moreover, to maintain an ideal BCS, entire kittens consumed 93 (95 % CI 87, 100) % of their theoretical intake at 26 weeks of age, and 79 (95 % CI 72, 87) % at 52 weeks of age, suggesting that the current energy recommendation is inappropriate for these kittens. PMID:22005425

  16. History of the study of human body composition: A brief review.

    PubMed

    Wang, ZiMian; Wang, Zhong-Ming; Heymsfield, Steven B.

    1999-01-01

    This review assembles a chronology of human body composition research with the goal of exposing historical roots and identifying future potential trends. Body composition research has emerged over the past several decades as a distinct field, and for many scientists body composition is their primary investigative focus. Technological advances will likely move the field forward and, ultimately, help to expand knowledge of human body composition variability in health and disease. Am. J. Hum. Biol. 11:157-165, 1999. Copyright 1999 Wiley-Liss, Inc.

  17. Biological characteristics of the MG-63 human osteosarcoma cells on composite tantalum carbide/amorphous carbon films.

    PubMed

    Chang, Yin-Yu; Huang, Heng-Li; Chen, Ya-Chi; Hsu, Jui-Ting; Shieh, Tzong-Ming; Tsai, Ming-Tzu

    2014-01-01

    Tantalum (Ta) is a promising metal for biomedical implants or implant coating for orthopedic and dental applications because of its excellent corrosion resistance, fracture toughness, and biocompatibility. This study synthesizes biocompatible tantalum carbide (TaC) and TaC/amorphous carbon (a-C) coatings with different carbon contents by using a twin-gun magnetron sputtering system to improve their biological properties and explore potential surgical implant or device applications. The carbon content in the deposited coatings was regulated by controlling the magnetron power ratio of the pure graphite and Ta cathodes. The deposited TaC and TaC/a-C coatings exhibited better cell viability of human osteosarcoma cell line MG-63 than the uncoated Ti and Ta-coated samples. Inverted optical and confocal imaging was used to demonstrate the cell adhesion, distribution, and proliferation of each sample at different time points during the whole culture period. The results show that the TaC/a-C coating, which contained two metastable phases (TaC and a-C), was more biocompatible with MG-63 cells compared to the pure Ta coating. This suggests that the TaC/a-C coatings exhibit a better biocompatible performance for MG-63 cells, and they may improve implant osseointegration in clinics.

  18. Biological characteristics of the MG-63 human osteosarcoma cells on composite tantalum carbide/amorphous carbon films.

    PubMed

    Chang, Yin-Yu; Huang, Heng-Li; Chen, Ya-Chi; Hsu, Jui-Ting; Shieh, Tzong-Ming; Tsai, Ming-Tzu

    2014-01-01

    Tantalum (Ta) is a promising metal for biomedical implants or implant coating for orthopedic and dental applications because of its excellent corrosion resistance, fracture toughness, and biocompatibility. This study synthesizes biocompatible tantalum carbide (TaC) and TaC/amorphous carbon (a-C) coatings with different carbon contents by using a twin-gun magnetron sputtering system to improve their biological properties and explore potential surgical implant or device applications. The carbon content in the deposited coatings was regulated by controlling the magnetron power ratio of the pure graphite and Ta cathodes. The deposited TaC and TaC/a-C coatings exhibited better cell viability of human osteosarcoma cell line MG-63 than the uncoated Ti and Ta-coated samples. Inverted optical and confocal imaging was used to demonstrate the cell adhesion, distribution, and proliferation of each sample at different time points during the whole culture period. The results show that the TaC/a-C coating, which contained two metastable phases (TaC and a-C), was more biocompatible with MG-63 cells compared to the pure Ta coating. This suggests that the TaC/a-C coatings exhibit a better biocompatible performance for MG-63 cells, and they may improve implant osseointegration in clinics. PMID:24760085

  19. Biological Characteristics of the MG-63 Human Osteosarcoma Cells on Composite Tantalum Carbide/Amorphous Carbon Films

    PubMed Central

    Chang, Yin-Yu; Huang, Heng-Li; Chen, Ya-Chi; Hsu, Jui-Ting; Shieh, Tzong-Ming; Tsai, Ming-Tzu

    2014-01-01

    Tantalum (Ta) is a promising metal for biomedical implants or implant coating for orthopedic and dental applications because of its excellent corrosion resistance, fracture toughness, and biocompatibility. This study synthesizes biocompatible tantalum carbide (TaC) and TaC/amorphous carbon (a-C) coatings with different carbon contents by using a twin-gun magnetron sputtering system to improve their biological properties and explore potential surgical implant or device applications. The carbon content in the deposited coatings was regulated by controlling the magnetron power ratio of the pure graphite and Ta cathodes. The deposited TaC and TaC/a-C coatings exhibited better cell viability of human osteosarcoma cell line MG-63 than the uncoated Ti and Ta-coated samples. Inverted optical and confocal imaging was used to demonstrate the cell adhesion, distribution, and proliferation of each sample at different time points during the whole culture period. The results show that the TaC/a-C coating, which contained two metastable phases (TaC and a-C), was more biocompatible with MG-63 cells compared to the pure Ta coating. This suggests that the TaC/a-C coatings exhibit a better biocompatible performance for MG-63 cells, and they may improve implant osseointegration in clinics. PMID:24760085

  20. Effect of added silicon carbide nanowires and carbon nanotubes on mechanical properties of 0-3 natural rubber composites

    NASA Astrophysics Data System (ADS)

    Janyakunmongkol, Khantichai; Nhuapeng, Wim; Thamjaree, Wandee

    2016-01-01

    In this work, the mechanical properties of 0-3 nanocomposite materials containing silicon carbide nanowires (SiCNWs), carbon nanotubes (CNTs), and natural rubber were studied. The SiCNWs and CNTs were used as reinforcement fiber whereas natural rubber was used as the matrix phase. The chemical vapor depositions (CVD) was used for synthesizing the nanowire and nanotube phases. The volume fraction of reinforcement was varied from 0 to 10%. The nanophases were mixed in the natural rubber matrix and molded by the hand lay-up technique. The mechanical properties of the samples were examined and compared with those of neat natural rubber. From the results, it was found that the hardness and density of the samples increased with the quantities of nanophases. The nanocomposites with a volume fraction of 10% exhibited maximum hardness (50.5 SHORE A). The maximum tensile strength and extent of elongation at break of the samples were obtained from the 4% volume fraction sample, which were 16.13 MPa and 1,540%, respectively.

  1. Effects of Smoking Cessation on Body Composition in Postmenopausal Women

    PubMed Central

    Litt, Mark D.; Kenny, Anne M.; Oncken, Cheryl A.

    2010-01-01

    Abstract Background Smoking cessation is associated with weight gain, but the effects of smoking cessation on measures of body composition (BC) have not been adequately evaluated. The purpose of this study is to examine the effects of 16 months of cigarette abstinence on areas of BC measured by dual-energy x-ray absorptiometry (DXA). Methods One hundred fifty-two postmenopausal women participated in a smoking cessation study using the nicotine patch. Secondary analyses were conducted on data from 119 subjects (age 56 ± 7 years, range 41–78 years) who had had DXA scans at baseline and 16 months later. Participants were classified either as quitters (self-reported cigarette abstinence confirmed with exhaled carbon monoxide [co] ≤8 ppm at 3 and 16 months after quit date) or as continued smokers. BC was assessed using a General Electric Lunar DXA IQ machine. Four areas of BC (kg) were measured: whole body weight, fat mass, muscle mass, and functional skeletal muscle mass in arms and legs (ASM/ht2). Multivariate analysis of covariance (MANCOVA) assessed changes in BC in quitters vs. continued smokers between baseline and 16 months of follow-up. Increases in BC measures were evaluated as a function of increased calorie intake or change in physical activity, using linear regression. Results Quitters significantly increased body weight (p < 0.001), fat mass (p < 0.001), muscle mass (p = 0.04), and functional muscle mass (p = 0.004) over time, when baseline BC measures and other confounding factors were controlled. Regression analysis indicated change in BC could not be accounted for by calorie intake or physical activity. Conclusions Smoking cessation may be associated with increased fat and muscle mass in postmenopausal women. The novel finding of an increase in functional muscle mass suggests that smoking cessation could increase functional capacity. Further studies need to replicate these findings and examine mechanisms of these effects. PMID

  2. Relationship among serum taurine, serum adipokines, and body composition during 8-week human body weight control program.

    PubMed

    You, Jeong Soon; Park, Ji Yeon; Zhao, Xu; Jeong, Jin Seok; Choi, Mi Ja; Chang, Kyung Ja

    2013-01-01

    Human adipose tissue is not only a storage organ but also an active endocrine organ to release adipokines. This study was conducted to investigate the relationship among serum taurine and adipokine levels, and body composition during 8-week human body weight control program in obese female college students. The program consisted of diet therapy, exercise, and behavior modification. After the program, body weight, body fat mass, percent body fat, and body mass index (BMI) were significantly decreased. Serum triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels were significantly decreased. Also serum adiponectin level was significantly increased and serum leptin level was significantly decreased. There were no differences in serum taurine and homocysteine levels. The change of serum adiponectin level was positively correlated with change of body fat mass and percent body fat. These results may suggest that body fat loss by human body weight control program is associated with an increase in serum adiponectin in obese female college students. Therefore, further study such as taurine intervention study is needed to know more exact correlation between dietary taurine intake and serum adipokines or body composition.

  3. Effects of NUTRIOSE® dietary fiber supplementation on body weight, body composition, energy intake, and hunger in overweight men.

    PubMed

    Guerin-Deremaux, Laetitia; Li, Shuguang; Pochat, Marine; Wils, Daniel; Mubasher, Mohamed; Reifer, Cheryl; Miller, Larry E

    2011-09-01

    The objective of the present study was to determine the effectiveness of a soluble dietary fiber, NUTRIOSE(®), on body weight, body composition, energy intake and hunger in overweight Chinese men. The volunteers were randomized in double-blind fashion to 250 ml fruit juice supplemented with NUTRIOSE(®) (Test, n = 60) or a maltodextrin (Control, n = 60) at a dosage of 17 g twice daily for 12 weeks. Body weight, body composition were performed at 0, 4, 8 and 12 weeks while daily energy intake and hunger were assessed every 3 days. Test subjects had reductions in body weight (1.5 kg, P < 0.001), body mass index (0.5 kg/m(2), P < 0.001) and body fat percentage (0.3%, P < 0.001) versus Controls. NUTRIOSE(®) supplementation resulted in a lower daily energy intake (3,079 kJ/day, P < 0.001) with group differences noted as early as 3 days. Test subjects reported less hunger across the study period versus Controls (P < 0.01). NUTRIOSE(®) supplementation for 12 weeks results in body composition improvements and reduces body weight, energy intake and hunger in overweight men.

  4. Meteoritic Amino Acids: Diversity in Compositions Reflects Parent Body Histories

    PubMed Central

    2016-01-01

    The analysis of amino acids in meteorites dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of meteorite groups (exemplified by the Murchison meteorite) into meteorites of other types and classes. These new studies have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in meteorites, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain meteorites and across carbonaceous meteorite groups. Large l-enantiomeric excesses of some extraterrestrial protein amino acids (up to ∼60%) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent meteoritic analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work. PMID:27413780

  5. Meteoritic Amino Acids: Diversity in Compositions Reflects Parent Body Histories.

    PubMed

    Elsila, Jamie E; Aponte, José C; Blackmond, Donna G; Burton, Aaron S; Dworkin, Jason P; Glavin, Daniel P

    2016-06-22

    The analysis of amino acids in meteorites dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of meteorite groups (exemplified by the Murchison meteorite) into meteorites of other types and classes. These new studies have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in meteorites, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain meteorites and across carbonaceous meteorite groups. Large l-enantiomeric excesses of some extraterrestrial protein amino acids (up to ∼60%) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent meteoritic analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work. PMID:27413780

  6. Meteoritic Amino Acids: Diversity in Compositions Reflects Parent Body Histories.

    PubMed

    Elsila, Jamie E; Aponte, José C; Blackmond, Donna G; Burton, Aaron S; Dworkin, Jason P; Glavin, Daniel P

    2016-06-22

    The analysis of amino acids in meteorites dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of meteorite groups (exemplified by the Murchison meteorite) into meteorites of other types and classes. These new studies have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in meteorites, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain meteorites and across carbonaceous meteorite groups. Large l-enantiomeric excesses of some extraterrestrial protein amino acids (up to ∼60%) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent meteoritic analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work.

  7. Boron-carbide-aluminum and boron-carbide-reactive metal cermets

    DOEpatents

    Halverson, Danny C.; Pyzik, Aleksander J.; Aksay, Ilhan A.

    1986-01-01

    Hard, tough, lightweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidation step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modulus of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi.sqroot.in. These composites and methods can be used to form a variety of structural elements.

  8. Stress Rupture Behavior of Silicon Carbide Coated, Low Modulus Carbon/Carbon Composites. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Rozak, Gary A.; Wallace, John F.

    1988-01-01

    The disadvantages of carbon-carbon composites, in addition to the oxidation problem, are low thermal expansion, expensive fabrication procedures, and poor off axis properties. The background of carbon-carbon composites, their fabrication, oxidation, oxidation protection and mechanical testing in flexure are discussed.

  9. Microstructural, phase evolution and corrosion properties of silicon carbide reinforced pulse electrodeposited nickel-tungsten composite coatings

    NASA Astrophysics Data System (ADS)

    Singh, Swarnima; Sribalaji, M.; Wasekar, Nitin P.; Joshi, Srikant; Sundararajan, G.; Singh, Raghuvir; Keshri, Anup Kumar

    2016-02-01

    Silicon carbide (SiC) reinforced nickel-tungsten (Ni-W) coatings were successfully fabricated on steel substrate by pulse electrodeposition method (PED) and the amount of SiC was varied as 0 g/l, 2 g/l, and 5 g/l in Ni-W coating. Effect of subsequent addition of SiC on microstructures, phases and on corrosion property of the coating was investigated. Field emission scanning electron microscopy (FE-SEM) image of the surface morphology of the coating showed the transformation from the dome like structure to turtle shell like structure. X-ray diffraction (XRD) of Ni-W-5 g/l SiC showed the disappearance of (220) plane of Ni(W), peak splitting in major peak of Ni(W) and formation of distinct peak of W(Ni) solid solution. Absence of (220) plane, peak splitting and presence of W(Ni) solid solution was explained by the high resolution transmission electron microscopy (HR-TEM) images. Tafel polarization plot was used to study the corrosion property of the coatings in 0.5 M NaCl solution. Ni-W-5 g/l SiC coating was showed higher corrosion resistance (i.e. ∼21% increase in corrosion potential, Ecorr) compared to Ni-W coating. Two simultaneous phenomena have been identified for the enhanced corrosion resistance of Ni-W-5 g/l SiC coating. (a) Presence of crystallographic texture (b) formation of continuous double barrier layer of NiWO4 and SiO2.

  10. Dual-energy X-ray absorptiometry–based body volume measurement for 4-compartment body composition123

    PubMed Central

    Wilson, Joseph P; Mulligan, Kathleen; Fan, Bo; Sherman, Jennifer L; Murphy, Elizabeth J; Tai, Viva W; Powers, Cassidy L; Marquez, Lorena; Ruiz-Barros, Viviana

    2012-01-01

    Background: Total body volume (TBV), with the exclusion of internal air voids, is necessary to quantify body composition in Lohman's 4-compartment (4C) model. Objective: This investigation sought to derive a novel, TBV measure with the use of only dual-energy X-ray absorptiometry (DXA) attenuation values for use in Lohman's 4C body composition model. Design: Pixel-specific masses and volumes were calculated from low- and high-energy attenuation values with the use of first principle conversions of mass attenuation coefficients. Pixel masses and volumes were summed to derive body mass and total body volume. As proof of concept, 11 participants were recruited to have 4C measures taken: DXA, air-displacement plethysmography (ADP), and total body water (TBW). TBV measures with the use of only DXA (DXA-volume) and ADP-volume measures were compared for each participant. To see how body composition estimates were affected by these 2 methods, we used Lohman's 4C model to quantify percentage fat measures for each participant and compared them with conventional DXA measures. Results: DXA-volume and ADP-volume measures were highly correlated (R2 = 0.99) and showed no statistically significant bias. Percentage fat by DXA volume was highly correlated with ADP-volume percentage fat measures and DXA software-reported percentage fat measures (R2 = 0.96 and R2 = 0.98, respectively) but were slightly biased. Conclusions: A novel method to calculate TBV with the use of a clinical DXA system was developed, compared against ADP as proof of principle, and used in Lohman's 4C body composition model. The DXA-volume approach eliminates many of the inherent inaccuracies associated with displacement measures for volume and, if validated in larger groups of participants, would simplify the acquisition of 4C body composition to a single DXA scan and TBW measure. PMID:22134952

  11. Changes in body composition of cancer patients following combined nutritional support

    SciTech Connect

    Cohn, S.H.; Vartsky, D.; Vaswani, A.N.; Sawitsky, A.; Rai, K.; Gartenhaus, W.; Yasumura, S.; Ellis, K.J.

    1982-01-01

    The effects of combined nutritional support (parenteral, enteral, and oral) were measured in cancer patients unable to maintain normal alimentation.Changes in body composition were quantified by measurement of total body levels of nitrogen, potassium, water, and fat. The protein-calorie intake of the patients was also evaluated by dietary survey (4-day recall). Standard anthropometric and biochemical measurements for nutritional assessment were obtained for comparison. The dietary evaluation indicated that the dietary supplementation for all patients was more than adequate to meet their energy requirements. Determination of body composition indicated that change in body weight was equal to the sum of the changes in body protein, total body water, and total body fat. Information on the nature of the tissue gained was obtained by comparison of body composition data with the ratio of protein:water:lean body mass for normal tissue. The mean gain of protein in the cancer patients was quite small (0.3-0.6 kg). The main change in body weight appeared to be the result of gains in body water and body fat. The total body nitrogen to potassium ratio served to define the extent of tissue anabolism following hyperalimentation. The ratio dropped in the cancer patients following hyperalimentation toward the value of the control subjects on ad libitum diets. Total body nitrogen was determined by prompt gamma neutron activation analysis, total body potassium by whole-body counting. (JMT)

  12. Spark plasma sintering of silicon carbide, multi-walled carbon nanotube and graphene reinforced zirconium diboride ceramic composite

    NASA Astrophysics Data System (ADS)

    Balaraman Yadhukulakrishnan, Govindaraajan

    Scope and Method of Study: Space vehicles re-entering the earth's atmosphere experience very high temperatures due to aerodynamic heating. Ultra-high temperature ceramics (UHTC) with melting point higher than 3200°C are promising materials for thermal protection systems of such space vehicles re-entering the earth's atmosphere. Among several UHTC systems ZrB2 based ceramic composites are particularly important for thermal protection systems due to their better mechanical and thermoelectric properties and high oxidation resistance. In this study spark plasma sintering of SiC, carbon nanotubes (CNT) and graphene nano platelets (GNP) reinforced ZrB2 ultra-high temperature ceramic matrix composites is reported. Findings and Conclusions: Systematic investigations on the effect of reinforcement type (SiC, CNTs and GNP) and content (10-40 vol.% SiC, 2-6 vol.% CNTs and 2-6 vol.% GNP) on densification behavior, microstructure development, and mechanical properties (microhardness, bi-axial flexural strength, and indentation fracture toughness) are reported. With the similar SPS parameters near-full densification (>99% relative density) was achieved with 10-40 vol.% SiC, 4-6 vol.% CNT reinforced composites. Highly dense composites were obtained in 4-6 vol.% GNP reinforced composites. The SiC, CNT and GNP reinforcement improved the indentation fracture toughness of the composites through a range of toughening mechanisms, including particle shearing, crack deflection at the particle-matrix interface, and grain pull-outs for ZrB2-SiC composites, CNT pull-outs and crack deflection in ZrB2-CNT composites and crack deflection, crack bridging and GNP sheet pull-out for ZrB2 -GNP composites.

  13. Structure and amorphization of the oxide on the silicon carbide surface in an SiC{sub p}/Al composite

    SciTech Connect

    Gu, M.; Mei, Z.; Jin, Y.; Wu, Z.

    1999-04-09

    The particulate silicon carbide reinforced aluminum composite (SiCp/Al) can be made with isotropic properties in three dimensions. Meanwhile, conventional secondary fabrication methods can be used to produce a wide range of product forms at relatively low cost. The main difficulty encountered in the fabrication of SiCp/Al is the ``chemical compatibility,`` which prescribes the wettability and reactability at the interface between the SiC particle and the Al matrix. At low temperatures the wettability of SiCp/Al is poor which results in a very weak interfacial bonding between the SiCp and the Al. At high temperatures, molten Al rapidly reacts with SiCp to form a brittle Al{sub 4}C{sub 3}, which leads to a poor corrosion resistance and degraded mechanical properties. Two methods have been proposed to increase the wettability while preventing excessive reactions between the Al and the SiCp. The first is alloying of the Al matrix. The second is surface treatment of the SiC particle, such as the surface deposition of Al{sub 2}O{sub 3} and surface oxidation to SiO{sub 2}. Among various surface treatments, evolved so far, surface oxidation seems to be the best. The structure of this SiO{sub 2} layer was reported to be amorphous formed below 1,200 C and crystallized very rapid above 1,200 C. However, crystalline SiO{sub 2} oxidation layers on SiCp surface formed at 800--1,100 C were also reported. Discrepancies also exist in the literature pertinent to the effect of this layer on the interfacial reactions and mechanical properties of the SiCp/Al composites. The aim of the present work is to study the structure of the oxidation product on the as-oxidized and the after-composited SiC particles.

  14. Body composition changes in monkeys during long-term exposure to high acceleration fields

    NASA Technical Reports Server (NTRS)

    Pace, N.; Rahlmann, D. F.; Kodama, A. M.; Smith, A. H.

    1977-01-01

    Adult male pig-tailed monkeys, weighing 10-14 kg, were subjected to continuous centrifuging stress for 7 months in acceleration fields up to 2.5 g. In vivo analytical techniques were used to evaluate parameters of body composition, body-fluid distribution, and hematology. Statistically significant losses in total body mass, lean body mass, total body water, extracellular water content and interstitial water content proportional to the level of high g were demonstrated.

  15. Evaluation of body composition and nitrogen content of renal patients on chronic dialysis as determined by total body neutron activation

    SciTech Connect

    Cohn, S.H.; Brennan, B.L.; Yasumura, S.; Vartsky, D.; Vaswani, A.N.; Ellis, K.J.

    1983-07-01

    Total body protein (nitrogen), body cell mass (potassium), fat, and water were measured in 15 renal patients on maintenance hemodialysis (MHD). Total body nitrogen was measured by means of prompt ..gamma.. neutron activation analysis; total body water was determined with tritium labeled water; total body potassium was measured by whole body counting. The extracellular water was determined by a technique utilizing the measurement of total body chloride and plasma chloride. When compared with corresponding values of a control group of the same age, sex, and height, the protein content, body cell mass, and total body fat of the MHD patients were within the normal range. The only significant change was an increase in the extracellular water/body cell mass ratio in the male MHD patients compared to the control. The lack of significant difference of the nitrogen values of the MHD patients compared to matched controls suggests that dialysis minimizes any residual effects of uremic toxicity or protein-calorie malnutrition. These findings further suggest that there is a need to reevaluate the traditional anthropometric and biochemical standards of nutritional status for MHD patients. It was concluded that it is particularly important to measure protein stores of MHD patients with low protein intake to ascertain nutritional status. Finally, in vivo measurement of total body nitrogen and potassium for determination of body composition provides a simple, direct, and accurate assessment of the nutritional status of MHD patients.

  16. Body Composition Changes Resulting from Fluid Ingestion and Dehydration

    ERIC Educational Resources Information Center

    Girandola, Robert N.

    1977-01-01

    It is recommended that when obtaining measures of body density by hydrostatic weighing, the subjects normal level of hydration be ascertained, since variance in body fat calculation from the hyperhydrated to the hydrated state can amount to twenty percent (two percent in actual body fat). (MB)

  17. Analysis of stress-strain, fracture and ductility behavior of aluminum matrix composites containing discontinuous silicon carbide reinforcement

    NASA Technical Reports Server (NTRS)

    Mcdanels, D. L.

    1984-01-01

    Mechanical properties and stress-strain behavior for several types of commercially fabricated aluminum matrix composites, containing up to 40 vol % discontinuous SiC whisker, nodule, or particulate reinforcement were evaluated. It was found that the elastic modulus of the composites was isotropic, to be independent of type of reinforcement, and to be controlled solely by the volume percentage of SiC reinforcement present. The yield/tensile strengths and ductility were controlled primarily by the matrix alloy and temper condition. Ductility decreased with increasing reinforcement content, however, the fracture strains observed were higher than those reported in the literature for this type of composite. This increase in fracture strain is attributed to cleaner matrix powder and increased mechanical working during fabrication. Conventional aluminum and titanium structural alloys were compared and have shown that the properties of these low cost, lightweight composites have good potential for application to aerospace structures.

  18. Effect of aspect ratio and liquid-phase content on densification of alumina-silicon carbide whisker composites

    SciTech Connect

    Tiegs, T.N.; Dillard, D.M. . Metals and Ceramics Div.)

    1990-05-01

    This paper reports that densification of alumina-SiC whisker composites by pressureless sintering is inhibited as a result of whisker interference with particle rearrangement and composite shrinkage. Reduction of the aspect ratio improves densification by improving particle/whisker packing for increased green densities and enhances the ability of the whiskers to rearrange themselves during sintering. Increasing the amount of liquid phases present during sintering also improves densification by aiding whisker rearrangement.

  19. Physical Best--Body Composition in the Assessment of Youth Fitness.

    ERIC Educational Resources Information Center

    Going, Scott

    1988-01-01

    The article explains why body composition measurements are considered a necessary and important part of the "physical best" concept in the assessment of health-related physical fitness and presents evidence that the skinfold technique is both reliable and valid for estimating body composition in both children and youth. (CB)

  20. Comparison of Methods for Assessing Body Composition Changes during Weight Loss.

    ERIC Educational Resources Information Center

    Weyers, Anna M.; Mazzetti, Scott A.; Love, Dawn M.; Gomez, Ana L.; Kraemer, William J.; Volek, Jeff S.

    2002-01-01

    Investigated whether dual-energy x-ray absorptiometry (DXA) and air displacement plethysmography (ADP) would detect similar changes in body composition after moderate weight loss. Twenty adults had their body composition measured using DXA and ADP before and after an 8-week weight loss program. Overall, both DXA and ADP detected similar changes in…

  1. Ultrasound use for body composition and carcass quality assessment in cattle and lambs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic evaluation for carcass quality traits has evolved over time, in large part due to introduction of new technology such as ultrasound measures of body composition. Ultrasound measured body composition traits emulate important carcass traits, are very informative for selection purposes, are ac...

  2. Does Upper Extremity Training Influence Body Composition after Spinal Cord Injury?

    PubMed Central

    Fisher, Justin A.; McNelis, Meredith A.; Gorgey, Ashraf S.; Dolbow, David R.; Goetz, Lance L.

    2015-01-01

    Spinal cord injury (SCI) leads to serious body composition adaptations characterized by increasing whole body fat mass and decreased soft tissue lean mass (LM). These adaptations in body composition may lead to several cardio-metabolic disorders that reduce the quality of life, increase patients’ and caregivers’ burden and eventually leads to mortality. Exercise, an appropriate dietary regimen, and an active lifestyle may alleviate several of the negative effects on body composition after a SCI. Today however, there is no established consensus on the recommended dose, frequency or type of exercise to ameliorate several of the body composition sequelae after an acute SCI. Resistance training has been previously recommended as an effective strategy to restore soft tissue LM and decrease fat mass (FM). The strategy can be simply implemented as a routine home-based training program using free weights or resistance bands after a SCI. Additionally, upper extremity (UE) circuit resistance training has been previously used to improve cardiovascular and metabolic parameters after a SCI; however compared to the vast knowledge regarding the able-bodied (AB) population, the effects of UE circuit resistance training on body composition after a SCI is not well established. In summary, the available evidence does not support the rationale that UE circuit resistance training can lead to positive adaptations in body composition after a SCI. Further studies are suggested to examine the effects of UE circuit resistance training on body composition. PMID:26236549

  3. Assessment of nutritional status in cancer--the relationship between body composition and pharmacokinetics.

    PubMed

    Prado, Carla M M; Maia, Yara L M; Ormsbee, Michael; Sawyer, Michael B; Baracos, Vickie E

    2013-10-01

    Several nutritional assessment tools have been used in oncology settings to monitor nutritional status and its associated prognostic significance. Body composition is fundamental for the assessment of nutritional status. Recently, the use of accurate and precise body composition tools has significantly added to the value of nutritional assessment in this clinical setting. Computerized tomography (CT) is an example of a technique which provides state-of-the-art assessment of body composition. With use of CT images, a great variability in body composition of cancer patients has been identified even in people with identical body weight or body mass index. Severe muscle depletion (sarcopenia) has emerged as a prevalent body composition phenotype which is predictive of poor functional status, shorter time to tumor progression, shorter survival, and higher incidence of dose-limiting toxicity. Variability in body composition of cancer patients may be a source of disparities in the metabolism of cytotoxic agents. Future clinical trials investigating dose reductions in patients with sarcopenia and dose-escalating studies based on pre-treatment body composition assessment have the potential to alter cancer treatment paradigms.

  4. Assessment of body composition by air-displacement plethysmography: influence of body temperature and moisture.

    PubMed

    Fields, David A; Higgins, Paul B; Hunter, Gary R

    2004-04-01

    BACKGROUND: To investigate the effect of body temperature and moisture on body fat (%fat), volume and density by air-displacement plethysmography (BOD POD). METHODS: %fat, body volume and density by the BOD POD before (BOD PODBH) and immediately following hydrostatic weighing (BOD PODFH) were performed in 32 healthy females (age (yr) 33 +/- 11, weight (kg) 64 +/- 14, height (cm) 167 +/- 7). Body temperature and moisture were measured prior to BOD PODBH and prior to BOD PODFH with body moisture defined as the difference in body weight (kg) between the BOD PODBH and BOD PODFH measurements. RESULTS: BOD PODFH %fat (27.1%) and body volume (61.5 L) were significantly lower (P body density (1.0379 g/cm3) significantly higher (P body volume (61.7 L), and body density (1.0341 g/cm3). A significant increase in body temperature (~0.6 degrees C; P body moisture (0.08 kg; P Body surface area was positively associated with the difference in %fat independent of changes in body temperature and moisture, r = 0.30, P < 0.05. CONCLUSION: These data demonstrate for the first time that increases in body heat and moisture result in an underestimation of body fat when using the BOD POD, however, the precise mechanism remains unidentified.

  5. Applicability of body composition techniques and constants for children and youths.

    PubMed

    Lohman, T G

    1986-01-01

    This review has focused on the chemical immaturity of children and the implications for body composition estimates. Prepubescent and pubescent children deviate considerably in fat-free body composition from the adult reference male, and this has lead investigators to overestimate body fatness in this population using conventional body composition formulas. The use of multicomponent approaches to body composition to obtain more accurate estimates of body fatness in children has provided new information on the body composition of this population. Sex- and age-specific constants, to replace those derived from the reference male, are suggested for further testing and verification as well as for use in the clinical setting. The chemical immaturity in children has its greatest effect on estimating the extent of obesity in children 6 to 11 years of age and in estimating body fatness in the lean, athletic, prepubescent population. Previous estimates of the growth rate of fat and fat-free body are also affected by chemical immaturity. Further research is needed to study the impact of physical activity and inactivity on the composition of the fat-free body during growth, to develop constants for more accurate estimates of fatness in physically active samples of all ages and to validate the constants presented in the less active populations. Future research with multicomponent body composition systems in all populations of children and youth is essential for progress in this area. Results will have an important contribution to the estimation of childhood obesity, prediction of minimal weight in the athletic population and estimates of growth rate of fat and fat-free body mass. The development of body composition methodologies which more accurately measure the growth of muscle and bone as well as fat is a major challenge ahead.

  6. Symmetry considerations in the scattering of identical composite bodies

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W.; Deutchman, P. A.

    1986-01-01

    Previous studies of the interactions between composite particles were extended to the case in which the composites are identical. The form of the total interaction potential matrix elements was obtained, and guidelines for their explicit evaluation were given. For the case of elastic scattering of identical composites, the matrix element approach was shown to be equivalent to the scattering amplitude method.

  7. Dietary supplements for improving body composition and reducing body weight: where is the evidence?

    PubMed

    Manore, Melinda M

    2012-04-01

    Weight-loss supplements typically fall into 1 of 4 categories depending on their hypothesized mechanism of action: products that block the absorption of fat or carbohydrate, stimulants that increase thermogenesis, products that change metabolism and improve body composition, and products that suppress appetite or give a sense of fullness. Each category is reviewed, and an overview of the current science related to their effectiveness is presented. While some weight-loss supplements produce modest effects (<2 kg weight loss), many have either no or few randomized clinical trials examining their effectiveness. A number of factors confound research results associated with the efficacy of weight-loss supplements, such as small sample sizes, short intervention periods, little or no follow-up, and whether the supplement is given in combination with an energy-restricted diet or increased exercise expenditure. There is no strong research evidence indicating that a specific supplement will produce significant weight loss (>2 kg), especially in the long term. Some foods or supplements such as green tea, fiber, and calcium supplements or dairy products may complement a healthy lifestyle to produce small weight losses or prevent weight gain over time. Weight-loss supplements containing metabolic stimulants (e.g., caffeine, ephedra, synephrine) are most likely to produce adverse side effects and should be avoided.

  8. Anthropometry and Body Composition Status during Ramadan among Higher Institution Learning Centre Staffs with Different Body Weight Status

    PubMed Central

    Rozano, Nurismalina; Abd Hadi, Norhayati; Mat Nor, Mohd Nasir; Dandinasivara Venkateshaiah, Muralidhara

    2013-01-01

    This study was done to observe the anthropometry and body composition changes before, during, and after the holy month of Ramadan. This study was carried out on 46 staff from one of the local universities, which comprised of 14 males and 32 females ranging in age from 25 to 40 years old. There were four sessions done to complete this study, namely, a week before Ramadan (T1), 1st week of Ramadan (T2), 3rd week of Ramadan (T3), and a month after Ramadan (T4). All subjects were assessed according to weight, body circumference, and body composition status. It was found that subjects with different weight status showed a significant reduction in weight (P < 0.01) but no significant reduction in body fat percentage (P < 0.05). The findings suggest that weight reduction does not promise a reduction in body fat. Changes in neck circumference were only found in normal subjects. Hence, it can be said that overweight and obese subjects showed no changes in anthropometry status during Ramadan. No changes in body composition were reported in all three weight groups except for trunk body fat. In conclusion, normal subjects showed significant changes in various anthropometry parameters, but overweight and obese subjects showed no obvious difference. PMID:24311975

  9. Fabrication of thorium bearing carbide fuels

    DOEpatents

    Gutierrez, R.L.; Herbst, R.J.; Johnson, K.W.R.

    Thorium-uranium carbide and thorium-plutonium carbide fuel pellets have been fabricated by the carbothermic reduction process. Temperatures of 1750/sup 0/C and 2000/sup 0/C were used during the reduction cycle. Sintering temperatures of 1800/sup 0/C and 2000/sup 0/C were used to prepare fuel pellet densities of 87% and > 94% of theoretical, respectively. The process allows the fabrication of kilogram quantities of fuel with good reproductibility of chemical and phase composition.

  10. Reinforcement of tungsten carbide grains by nanoprecipitates in cemented carbides

    NASA Astrophysics Data System (ADS)

    Liu, Xingwei; Song, Xiaoyan; Wang, Haibin; Hou, Chao; Liu, Xuemei; Wang, Xilong

    2016-10-01

    In contrast to the conventional method that obtains a high fracture strength of tungsten carbide-cobalt (WC-Co) cemented carbides by reducing WC grain size to near-nano or nanoscale, a new approach has been developed to achieve ultrahigh fracture strength by strengthening the WC grains through precipitate reinforcement. The cemented carbides were prepared by liquid-state sintering the in situ synthesized WC-Co composite powders with a little excess carbon and pre-milled Cr3C2 particles having different size scales. It was found that the nanoscale dispersed particles precipitate in the WC grains, which mainly have a coherent or semi-coherent interface with the matrix. The pinning effect of the nanoparticles on the motion of dislocations within the WC grains was observed. The mechanisms for the precipitation of nanoparticles in the WC grains were discussed, based on which a new method to enhance the resistance against the transgranular fracture of cemented carbides was proposed.

  11. Reinforcement of tungsten carbide grains by nanoprecipitates in cemented carbides.

    PubMed

    Liu, Xingwei; Song, Xiaoyan; Wang, Haibin; Hou, Chao; Liu, Xuemei; Wang, Xilong

    2016-10-14

    In contrast to the conventional method that obtains a high fracture strength of tungsten carbide-cobalt (WC-Co) cemented carbides by reducing WC grain size to near-nano or nanoscale, a new approach has been developed to achieve ultrahigh fracture strength by strengthening the WC grains through precipitate reinforcement. The cemented carbides were prepared by liquid-state sintering the in situ synthesized WC-Co composite powders with a little excess carbon and pre-milled Cr3C2 particles having different size scales. It was found that the nanoscale dispersed particles precipitate in the WC grains, which mainly have a coherent or semi-coherent interface with the matrix. The pinning effect of the nanoparticles on the motion of dislocations within the WC grains was observed. The mechanisms for the precipitation of nanoparticles in the WC grains were discussed, based on which a new method to enhance the resistance against the transgranular fracture of cemented carbides was proposed.

  12. Reinforcement of tungsten carbide grains by nanoprecipitates in cemented carbides.

    PubMed

    Liu, Xingwei; Song, Xiaoyan; Wang, Haibin; Hou, Chao; Liu, Xuemei; Wang, Xilong

    2016-10-14

    In contrast to the conventional method that obtains a high fracture strength of tungsten carbide-cobalt (WC-Co) cemented carbides by reducing WC grain size to near-nano or nanoscale, a new approach has been developed to achieve ultrahigh fracture strength by strengthening the WC grains through precipitate reinforcement. The cemented carbides were prepared by liquid-state sintering the in situ synthesized WC-Co composite powders with a little excess carbon and pre-milled Cr3C2 particles having different size scales. It was found that the nanoscale dispersed particles precipitate in the WC grains, which mainly have a coherent or semi-coherent interface with the matrix. The pinning effect of the nanoparticles on the motion of dislocations within the WC grains was observed. The mechanisms for the precipitation of nanoparticles in the WC grains were discussed, based on which a new method to enhance the resistance against the transgranular fracture of cemented carbides was proposed. PMID:27609195

  13. Analysis of stress-strain, fracture, and ductility behavior of aluminum maxtrix composites containing discontinuous silicon carbide reinforcement

    NASA Technical Reports Server (NTRS)

    Mcdanels, D. L.

    1985-01-01

    Mechanical properties and stress-strain behavior were evaluated for several types of commercially fabricated aluminum matrix composites, containing up to 40 vol pct discontinuous SiC whisker, nodule, or particulate reinforcement. The elastic modulus of the composites was found to be isotropic, to be independent of type of reinforcement, and to be controlled solely by the volume percentage of SiC reinforcement present. The yield/tensile strengths and ductility were controlled primarily by the matrix alloy and temper condition. Type and orientation of reinforcement had some effect on the strengths of composites, but only for those in which the whisker reinforcement was highly oriented. Ductility decreased with increasing reinforcement content; however, the fracture strains observed were higher than those reported in the literature for this type of composite. This increase in fracture strain was probably attributable to cleaner matrix powder, better mixing, and increased mechanical working during fabrication. Comparison of properties with conventional aluminum and titanium structural alloys showed that the properties of the low-cost, lightweight composites demonstrated very good potential for application to aerospace structures.

  14. Centrifugal casting of ZA8 zinc alloy and composite A356/silicon carbide: Study and modeling of phases' and particles' segregation

    NASA Astrophysics Data System (ADS)

    Balout, Bahaa

    Centrifugation is a casting technology that allows the production of cylindrical and graduated parts with different mechanical properties through the section. The need for materials with good quality and specific mechanical properties has been driven this technology in order to produce different types of materials such as zinc alloys and graduated metal matrix composites reinforced by hard and wear resistant particles. The goal of this research project is to study and model the eutectic macrosegregation, the solidification speed, and the speeds of solidification fronts during centrifugal casting of ZA8 zinc-aluminum alloy in order to improve the part quality and increase its strength and field reliability. Moreover, the segregation of the particles during centrifugal casting of an aluminum matrix composite reinforced by silicon carbide particles (A356/SiC) is also studied to improve and control the graduation of the parts. The cooling rate, the speed, acceleration/deceleration, displacement, and segregation of the particles across the section will be modeled by discretization of Stokes' law in time in order to take into consideration the change in the centrifugal radius and melt viscosity during cooling process. This study will allow the control of the graduation degree of particles across the section in order to improve the properties and wear resistance of the composite. This composite can be used in systems where friction is critical and load is high (reinforcements of parts for the cylinders of pneumatic systems). The results show that the maximum macrosegregation zone of the eutectic across the casting section corresponds to the last point of solidification. The eutectic macrosegregation produced during centrifugal casting of thin walled part is a normal segregation which varies depending on the solidification speed and the ratio between the speeds of solidification fronts. On the other hand, it was found that the position and volume fraction of the particles

  15. Influence of carbides and microstructure of CoCrMo alloys on their metallic dissolution resistance.

    PubMed

    Valero-Vidal, C; Casabán-Julián, L; Herraiz-Cardona, I; Igual-Muñoz, A

    2013-12-01

    CoCrMo alloys are passive and biocompatible materials widely used as joint replacements due to their good mechanical properties and corrosion resistance. Electrochemical behaviour of thermal treated CoCrMo alloys with different carbon content in their bulk alloy composition has been analysed. Both the amount of carbides in the CoCrMo alloys and the chemical composition of the simulated body fluid affect the electrochemical properties of these biomedical alloys, thus passive dissolution rate was influenced by the mentioned parameters. Lower percentage of carbon in the chemical composition of the bulk alloy and thermal treatments favour the homogenization of the surface (less amount of carbides), thus increasing the availability of Cr to form the oxide film and improving the corrosion resistance of the alloy. PMID:24094174

  16. Evaluation of body composition during low-dose estrogen oral contraceptives treatment.

    PubMed

    Franchini, M; Caruso, C; Nigrelli, S; Poggiali, C

    1995-01-01

    The effect of two low-dose oral contraceptives (OCs) on weight and body composition was evaluated in 80 family planning clinic outpatients 18-43 years of age. These women were randomly assigned to receive OCs containing either 20 mcg ethinyl estradiol and 150 mcg desogestrel or 30 mcg ethinyl estradiol and 75 mcg gestodene. 20 IUD users served as controls. Anthropometric measurements and body composition (estimated by Bioelectrical Impedance Analysis) were assessed at baseline and after 6 and 12 months of OC use. In all three groups, body weight, body mass index, total body water, and body cellular mass remained unchanged during the 12-month study period. These findings confirm that the new low-dose OCs have no significant effects on body weight or composition.

  17. Fraction of carbon-free body mass as oxygen is a constant body composition ratio in men.

    PubMed

    Wang, Z; Deurenberg, P; Wang, W; Pierson, R N; Heymsfield, S B

    1998-06-01

    Although elements are the foundation of the human body, information concerning the atomic level of body composition is still limited. The aim of this study was to explore potentially constant relationships among elements found in vivo. Based on the known stoichiometries of relevant chemical components, a theoretical model was derived, suggesting the existence of a relatively constant ratio of total body oxygen to carbon-free body mass (TBO/CFM) in men. Eight elements (C, H, N, Ca, P, K, Na and Cl ) were measured in 22 healthy male subjects by using in vivo neutron activation-40K whole-body counting, and TBO was calculated as the difference between body mass and the sum of the eight measured elements. TBO (in kg) was significantly correlated with CFM (in kg): TBO = 0.829 x CFM - 1.8; r = 0.998, P < 0.001, standard error of estimate = 0.4 kg. The ratio of TBO to CFM was relatively constant, mean +/- SD at 0. 800 +/- 0.009 with a CV of 1.1%. Oxygen and carbon are the two most abundant elements in the human body. The discovery of a constant relationship between oxygen and carbon is not only helpful for understanding the atomic level of body composition, but also provides the possibility of estimating the content of specific elements in vivo.

  18. [Human body composition during extended stay in microgravity].

    PubMed

    Noskov, V B; Nichiporuk, I A; Vasilieva, G Yu; Smirnov, Yu I

    2015-01-01

    According to the Sprut-2 protocol, bio-impedancemetry of ISS cosmonauts was performed once a month and also before and after mission. Multiple non-invasive body measurements were carried out in 15 cosmonauts in real time. Relocation of extracellular liquid along the body axis led to its reduction in legs and, on the contrary, an increase in the abdomen. Volumes of total body liquid as well as intra- and extracellular liquids decreased in comparison with pre-flight levels. Lean body mass also became less in microgravity, whereas fat mass showed an increase. PMID:25958462

  19. [Human body composition during extended stay in microgravity].

    PubMed

    Noskov, V B; Nichiporuk, I A; Vasilieva, G Yu; Smirnov, Yu I

    2015-01-01

    According to the Sprut-2 protocol, bio-impedancemetry of ISS cosmonauts was performed once a month and also before and after mission. Multiple non-invasive body measurements were carried out in 15 cosmonauts in real time. Relocation of extracellular liquid along the body axis led to its reduction in legs and, on the contrary, an increase in the abdomen. Volumes of total body liquid as well as intra- and extracellular liquids decreased in comparison with pre-flight levels. Lean body mass also became less in microgravity, whereas fat mass showed an increase.

  20. Effect of Carbide Ceramic Zone on Wear Resistance of the (Fe,Cr)7C3/Fe Surface Gradient Composite

    NASA Astrophysics Data System (ADS)

    Ye, Fangxia; Xu, Yunhua; Hojamberdiev, Mirabbos; Lai, Yujun; Wang, Chong; Wang, Xin

    2015-08-01

    In this work, we report on the influence of microstructure and mechanical properties of the (Fe,Cr)7C3 ceramic zone on wear resistance of the (Fe,Cr)7C3/Fe surface gradient composite fabricated by in situ synthesis method followed by a post-heat treatment at 1100 °C for 20 h in argon atmosphere. The phase composition, microstructure, nanoindentation hardness, elastic modulus, fracture toughness, and relative wear resistance of the (Fe,Cr)7C3/Fe surface gradient composite were investigated by means of x-ray diffraction, scanning electron microscopy, nanoindentation tester, and wear resistance testing instrument, respectively. The XRD results showed that (Fe,Cr)7C3 is the predominant crystalline phases in the fabricated composite. The volume fraction of the (Fe,Cr)7C3 particulates formed has a gradient distribution from the surface to the iron matrix, and the microstructure also changes significantly. The (Fe,Cr)7C3 bulk ceramic zone with the volume fraction of about 100% and the (Fe,Cr)7C3 dense ceramic zone with the volume fraction of about 90% were synthesized on the upper surface of the (Fe,Cr)7C3/Fe surface gradient composite, respectively. The average nanoindentation hardness and elastic modulus of the (Fe,Cr)7C3 bulk ceramic zone of the composite were determined to be 12.711 and 256.054 GPa, respectively. The fracture toughness of the (Fe,Cr)7C3 bulk ceramic zone is in the range of 2.06-4.19 MPa m1/2, and its relative wear resistance is about 56 times higher than that of the iron matrix. The (Fe,Cr)7C3 dense ceramic zone with rod-like, secondary (Fe,Cr)7C3 particulates was formed at the bottom of the (Fe,Cr)7C3 bulk ceramic zone. Rod-like, secondary (Fe,Cr)7C3 particulates are dense and grew in the direction of the iron substrate, providing higher wear resistance to the composite. The wear mechanisms of the (Fe,Cr)7C3 bulk and dense ceramic zones are considered to be microcutting, microcracking, and spalling pit.

  1. Carbon, nitrogen, magnesium, silicon, and titanium isotopic compositions of single interstellar silicon carbide grains from the Murchison carbonaceous chondrite

    NASA Technical Reports Server (NTRS)

    Hoppe, Peter; Amari, Sachiko; Zinner, Ernst; Ireland, Trevor; Lewis, Roy S.

    1994-01-01

    Seven hundred and twenty SiC grains from the Murchison CM2 chondrite, ranging in size from 1 to 10 micrometers, were analyzed by ion microprobe mass spectrometry for their C-isotopic compositions. Subsets of the grains were also analyzed for N (450 grains), Si (183 grains), Mg (179 grains), and Ti (28 grains) isotopes. These results are compared with previous measurements on 41 larger SiC grains (up to 15 x 26 micrometers) from a different sample of Murchison analyzed by Virag et al. (1992) and Ireland, Zinner, & Amari (1991a). All grains of the present study are isotopically anomalous with C-12/C-13 ratios ranging from 0.022 to 28.4 x solar, N-14/N-15 ratios from 0.046 to 30 x solar, Si-29/Si-28 from 0.54 to 1.20 x solar, Si-30/Si-28 from 0.42 to 1.14 x solar, Ti-49/Ti-48 from 0.96 to 1.95 x solar, and Ti-50/Ti-48 from 0.94 to 1.39 x solar. Many grains have large Mg-26 excesses from the decay of Al-26 with inferred Al-26/Al-27 ratios ranging up to 0.61, or 12,200 x the ratio of 5 x 10(exp -5) inferred for the early solar system. Several groups can be distinguished among the SiC grains. Most of the grains have C-13 and N-14 excesses, and their Si isotopic compositions (mostly excesses in Si-29 and Si-30) plot close to a slope 1.34 line on a Delta Si-29/Si-28 versus Delta Si-30/Si-28 three-isotope plot. Grains with small C-12/C-13 ratios (less than 10) tend to have smaller or no N-14 excesses and high Al-26/Al-27 ratios (up to 0.01). Grains with C-12/C-13 greater than 150 fall into two groups: grains X have N-15 excesses and Si-29 and Si-30 deficits and the highest (0.1 to 0.6) Al-26/Al-27 ratios; grains Y have N-14 excesses and plot on a slope 0.35 line on a Si three-isotope plot. In addition, large SiC grains of the Virag et al. (1992) study fall into three-distinct clusters according to their C-, Si-, and Ti-isotopic compositions. The isotopic diversity of the grains and the clustering of their isotopic compositions imply distinct and multiple stellar sources

  2. Functional body composition: insights into the regulation of energy metabolism and some clinical applications.

    PubMed

    Müller, M J; Bosy-Westphal, A; Later, W; Haas, V; Heller, M

    2009-09-01

    The application of advanced methods and techniques and their continuous development enable detailed body composition analyses (BCAs) and modeling of body composition at different levels (e.g., at atomic, molecular, organ-tissue and whole body level). Functional body composition integrates body components into regulatory systems (e.g., on energy balance). Regulation of body weight is closely linked to the mass and function of individual body components. Fat mass is part of the energy intake regulatory feedback system. In addition, fat-free mass (FFM) and fat mass are both determinants of resting energy expenditure (REE). Up to 80% of the variance in energy intake and energy expenditure is explained by body composition. A deviation from normal associations between body components and function suggests a metabolic disequilibrium (e.g., in the REE-FFM relationship or in the plasma leptin-fat mass association) that may occur in response to weight changes and diseases. The concept of functional body composition adds to a more sophisticated view on nutritional status and diseases, as well as to a characterization of biomedical traits that will provide functional evidence relating genetic variants.

  3. Assessment of body composition by air-displacement plethysmography: influence of body temperature and moisture

    PubMed Central

    Fields, David A; Higgins, Paul B; Hunter, Gary R

    2004-01-01

    Background To investigate the effect of body temperature and moisture on body fat (%fat), volume and density by air-displacement plethysmography (BOD POD). Methods %fat, body volume and density by the BOD POD before (BOD PODBH) and immediately following hydrostatic weighing (BOD PODFH) were performed in 32 healthy females (age (yr) 33 ± 11, weight (kg) 64 ± 14, height (cm) 167 ± 7). Body temperature and moisture were measured prior to BOD PODBH and prior to BOD PODFH with body moisture defined as the difference in body weight (kg) between the BOD PODBH and BOD PODFH measurements. Results BOD PODFH %fat (27.1%) and body volume (61.5 L) were significantly lower (P ≤ 0.001) and body density (1.0379 g/cm3) significantly higher (P ≤ 0.001) than BOD PODBH %fat (28.9%), body volume (61.7 L), and body density (1.0341 g/cm3). A significant increase in body temperature (~0.6°C; P ≤ 0.001) and body moisture (0.08 kg; P ≤ 0.01) were observed between BOD PODBH and BOD PODFH. Body surface area was positively associated with the difference in %fat independent of changes in body temperature and moisture, r = 0.30, P < 0.05. Conclusion These data demonstrate for the first time that increases in body heat and moisture result in an underestimation of body fat when using the BOD POD, however, the precise mechanism remains unidentified. PMID:15059287

  4. Association of Mid-Life Changes in Body Size, Body Composition and Obesity Status with the Menopausal Transition

    PubMed Central

    Karvonen-Gutierrez, Carrie; Kim, Catherine

    2016-01-01

    The mid-life period is a critical window for increases in body weight and changes in body composition. In this review, we summarize the clinical experience of the menopausal transition by obesity status, and examine the evidence regarding the menopausal transition and reproductive hormones effects on body weight, body composition, or fat distribution. Mid-life obesity is associated with a different menopausal experience including associations with menstrual cycle length prior to the final menstrual period (FMP), age at the FMP, and higher prevalence of vasomotor symptoms. The menopausal transition is associated with weight gain and increased central body fat distribution; the majority of evidence suggests that changes in weight are due to chronological aging whereas changes in body composition and fat distribution are primarily due to ovarian aging. Continuous and regular physical activity during mid-life may be an efficacious strategy to counteract the age-related and menopause-related changes in resting energy expenditure and to prevent weight gain and abdominal adiposity deposition. PMID:27417630

  5. Association of Mid-Life Changes in Body Size, Body Composition and Obesity Status with the Menopausal Transition.

    PubMed

    Karvonen-Gutierrez, Carrie; Kim, Catherine

    2016-01-01

    The mid-life period is a critical window for increases in body weight and changes in body composition. In this review, we summarize the clinical experience of the menopausal transition by obesity status, and examine the evidence regarding the menopausal transition and reproductive hormones effects on body weight, body composition, or fat distribution. Mid-life obesity is associated with a different menopausal experience including associations with menstrual cycle length prior to the final menstrual period (FMP), age at the FMP, and higher prevalence of vasomotor symptoms. The menopausal transition is associated with weight gain and increased central body fat distribution; the majority of evidence suggests that changes in weight are due to chronological aging whereas changes in body composition and fat distribution are primarily due to ovarian aging. Continuous and regular physical activity during mid-life may be an efficacious strategy to counteract the age-related and menopause-related changes in resting energy expenditure and to prevent weight gain and abdominal adiposity deposition. PMID:27417630

  6. Conduction mechanism in boron carbide

    NASA Technical Reports Server (NTRS)

    Wood, C.; Emin, D.

    1984-01-01

    Electrical conductivity, Seebeck-coefficient, and Hall-effect measurements have been made on single-phase boron carbides, B(1-x)C(x), in the compositional range from 0.1 to 0.2 X, and between room temperature and 1273 K. The results indicate that the predominant conduction mechanism is small-polaron hopping between carbon atoms at geometrically inequivalent sites.

  7. Energy composition of diet affects muscle fiber recruitment, body composition, and growth trajectory in rainbow trout (Oncorhnychus mykiss)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Energy composition of diet affects muscle fiber recruitment, body composition, and growth trajectory in rainbow trout (Oncorhnychus mykiss) The cost and scarcity of key ingredients for aquaculture feed formulation call for a wise use of resources, especially dietary proteins and energy. For years t...

  8. Analysis of the body composition of Paralympic athletes: Comparison of two methods.

    PubMed

    Lemos, Valdir De Aquino; Alves, Eduardo Da Silva; Schwingel, Paulo Adriano; Rosa, João Paulo Pereira; Silva, Andressa Da; Winckler, Ciro; Vital, Roberto; De Almeida, Alexandre Aparecido; Tufik, Sergio; De Mello, Marco Túlio

    2016-11-01

    Body composition is a physiological variable associated with physical activity and, in some cases, is related to athletic performance. Our objectives were to describe the body composition of participants in three distinct Paralympic sports and to compare the values of body density and estimated body fat obtained from the Paralympic athletes on the National Team by air-displacement plethysmography (ADP) and by the anthropometric method (skinfolds (SFs)). The sample consisted of 70 volunteers of both genders. The body composition of the volunteers was evaluated using the ADP in a Bod Pod(®) and seven SFs. There were no significant differences between the values obtained by ADP and SF for body fat percentage (p = .58) and body density (p = .49). Analysis by Bland-Altman plots showed mean differences of 0.56 ± 4.94 (-9.12-10.23) and -0.0017 ± 0.0113 (-0.024-0.020) for body fat percentage and body density, respectively. In conclusion, body composition analyses of Paralympic athletes by the ADP and SF methods show similar results, and ADP should be used as the first option when available. When the use of ADP is not possible, estimating body density and fat percentage by SF is a viable alternative for Paralympic athletes when future comparisons will use the same analysis method.

  9. Ultrasonic Guided-Wave-Scan System Used to Characterize C-Enhanced Silicon Carbide Composite During Creep- Rupture Tests

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Cosgriff, Laura M.; Martin, Richard E.; Verrilli, Michael J.

    2005-01-01

    Ceramic matrix composites (CMCs) are being developed for advanced aerospace propulsion applications in order to save weight, improve reuse capability, and increase performance. However, mechanical and environmental loads applied to CMCs can cause degradation in the form of discrete flaws and distributed microdamage that can play a significant role in reducing desirable physical properties. Categories of microdamage include fiber/matrix debonding (interface failure), matrix microcracking, fiber fracture and buckling, oxidation, and second-phase formation. Distributed microdamage in CMCs has proven difficult to characterize nondestructively because of the complex microstructure and macrostructure of these materials, and a recent study regarding the durability of a ceramic matrix composite discussed the requirement for improved nondestructive evaluation (NDE) methods for monitoring degradation in these materials.

  10. Isotopic Composition of Molybdenum and Barium in Single Presolar Silicon Carbide Grains of Type A+B

    NASA Technical Reports Server (NTRS)

    Savina, M. R.; Tripa, C. E.; Pellin, M. J.; Davis, A. M.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2003-01-01

    Presolar SiC grains fall into several groups based on C, N, and Si isotopic compositions. Approximately 93% are defined as mainstream, having 10 less than C-12/C-13 less than 100 and N-14/N-15 ranging from 50 to 20,000. A number of studies have shown that the most likely sources of mainstream grains are low mass asymptotic giant branch stars. Models of nucleosynthesis in AGB stars reproduce the s-process enhancements seen in the heavy elements in mainstream SiC grains. Among the less common grains, A+B grains, which comprise approximately 3-4% of presolar SiC, are perhaps the least well understood. Recent studies by Amari et al. show that A+B grains can be divided into at least 4 groups based on their trace element concentration patterns. Of 20 grains studied, 7 showed trace element patterns consistent with condensation from a gas of solar system composition, while the rest had varying degrees of process enhancements. Our previous measurements on 3 A+B grains showed Mo of solar isotopic composition, but Zr with a strong enhancement in 96Zr, which is an r-process isotope but can be made in an sprocess if the neutron density is high enough to bridge the unstable Zr-95 (T(sub 1/2)= 64 d). The observation of Mo with solar system isotopic composition in the same grains is puzzling however. Meyer et al. have recently shown that a neutron burst mechanism can produce a high Zr-96/Zr-94 without enhancing Mo-100, however this model leads to enhancements in Mo-95 and Mo-97 not observed in A+B grains. We report here results of Mo measurements on 7 additional A+B grains, and Ba measurements on 2 A+B grains, and compare these to the previous studies.

  11. Method Developed for the High-Temperature Nondestructive Evaluation of Fiber-Reinforced Silicon Carbide Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.

    1998-01-01

    Ceramic matrix composites have emerged as candidate materials to allow higher operating temperatures (1000 to 1400 C) in gas turbine engines. A need, therefore, exists to develop nondestructive methods to evaluate material integrity at the material operating temperature by monitoring thermal and mechanical fatigue. These methods would also have potential as quality inspection tools. The goal of this investigation at the NASA Lewis Research Center is to survey and correlate the temperature-dependent damping and stiffness of advanced ceramic composite materials with imposed thermal and stress histories that simulate in-service turbine engine conditions. A typical sample size of 100 by 4 by 2 cubic millimeters, along with the specified stiffness and density, placed the fundamental vibration frequencies between 100 and 2000 Hz. A modified Forster apparatus seemed most applicable to simultaneously measure both damping and stiffness. Testing in vacuum reduced the effects of air on the measurements. In this method, a single composite sample is vibrated at its fundamental tone; then suddenly, the mechanical excitation is removed so that the sample's motion freely decays with time. Typical results are illlustrated in this paper.

  12. Body composition during fetal development and infancy through the age of 5 years.

    PubMed

    Toro-Ramos, T; Paley, C; Pi-Sunyer, F X; Gallagher, D

    2015-12-01

    Fetal body composition is an important determinant of body composition at birth, and it is likely to be an important determinant at later stages in life. The purpose of this work is to provide a comprehensive overview by presenting data from previously published studies that report on body composition during fetal development in newborns and the infant/child through 5 years of age. Understanding the changes in body composition that occur both in utero and during infancy and childhood, and how they may be related, may help inform evidence-based practice during pregnancy and childhood. We describe body composition measurement techniques from the in utero period to 5 years of age, and identify gaps in knowledge to direct future research efforts. Available literature on chemical and cadaver analyses of fetal studies during gestation is presented to show the timing and accretion rates of adipose and lean tissues. Quantitative and qualitative aspects of fetal lean and fat mass accretion could be especially useful in the clinical setting for diagnostic purposes. The practicality of different pediatric body composition measurement methods in the clinical setting is discussed by presenting the assumptions and limitations associated with each method that may assist the clinician in characterizing the health and nutritional status of the fetus, infant and child. It is our hope that this review will help guide future research efforts directed at increasing the understanding of how body composition in early development may be associated with chronic diseases in later life. PMID:26242725

  13. Iron Isotope Compositions of Achondritic Meteorites from Distinct Parent Bodies

    NASA Astrophysics Data System (ADS)

    Dybal, E. M. K.; Wadhwa, M.; Romaniello, S.; Hines, R.

    2016-08-01

    We report the Fe isotope compositions of primitive and differentiated achondrites. The goal was to study a variety of achondrites that formed on distinct planetesimals to gain insights into the effects of differentiation on Fe isotope fractionation.

  14. Deuterium oxide dilution kinetics to predict body composition in dairy goats

    SciTech Connect

    Brown, D.L.; Taylor, S.J.

    1986-04-01

    Body composition and D2O dilution kinetics were studied in 15 female goats ranging from 38.0 to 70.1 kg live weight. Infrared spectrophotometric analyses of blood samples drawn during the 4 d following D2O injections were used to estimate D2O space. All does were slaughtered without shrinking and analyzed for dry matter, fat, nitrogen, and ash content. Estimates of D2O space from the late slope of the dilution curve, together with live weight, were used to predict body composition. Conclusions were 1) deuterium oxide space with live body weight accounts for about 90% of the variation in dairy goat empty body fat, empty body nitrogen, and empty body dry matter; 2) less than half the variation in empty body ash is related to live weight and D2O space; and 3) D2O space estimates would be biased by accelerations in water turnover.

  15. Measuring Body Composition in Individuals with Intellectual Disability: A Scoping Review

    PubMed Central

    Casey, Amanda Faith

    2013-01-01

    Background. Research shows obesity to be more prevalent amongst individuals with intellectual disability (ID) making correct measurement of body composition crucial. This study reviewed the validity and reliability of methods used for assessing body composition in individuals with ID. Methods. Authors conducted electronic searches through PubMed (1990 to present) and PsycINFO (1990 to present) and assessed relevant articles independently based on scoping review guidelines. Reviewers included primary research related to the validity and reliability of body composition measures on individuals with ID. Results. Searches identified six articles assessing body composition methods used on individuals with ID including body mass index (BMI), skinfold thickness, bioelectrical impedance analysis (BIA), waist circumference, tibia length, and anthropometric girth measurements. BMI and waist circumference appear suitable measures but skinfold thickness measurements may not be advisable due to participants' noncompliance resulting in a lack of precision and inaccurate results. Conclusions. The current literature contains too few well-conducted studies to determine the precision and validity of body composition measures on individuals with ID. There may be a need to devise further regression equations that apply to individuals with specific types of ID in order to increase the reliability and validity of body composition measurements. PMID:23762539

  16. Body composition among Sri Lankan infants by 18*O dilution method and the validity of anthropometric equations to predict body fat against 18*O dilution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Body composition indicators provide a better guidance for growth and nutritional status of the infants. This study was designed to (1) measure the body composition of the Sri Lankan infants using a reference method, the 18*O dilution method; (2) calculate the body fat content of the infants using pu...

  17. A comparison of methods of assessment of body composition including neutron activation analysis of total body nitrogen.

    PubMed

    Lukaski, H C; Mendez, J; Buskirk, E R; Cohn, S H

    1981-08-01

    Fourteen healthy men underwent determinations of total body nitrogen (TBN) by prompt gamma neutron activation analysis and total body potassium (TBK) by whole body counting to estimate the muscle and nonmuscle components of the fat-free body mass (FFBM) and their protein contents. Comparison of FFBM estimated from TBN and TBK (60.6 +/- 6.9 kg, mean +/- SD), densitometry (62.3 +/- 7.1 kg), TBK alone (62.2 +/- 8.0 kg) and TBW (63.9 +/- 7.8 kg) showed no differences among the techniques. Similarly, there were neither differences in fat mass nor percent body fat among the methods. Analysis of the chemical composition of FFBM of this group showed TBK/FFBM = 62.6 +/- 2.3 mEq/kg, TBW/FFBM = 74.6 +/- 0.2%, TBN/FFBM = 32.74 +/- 1.09 g/kg, protein/FFBM = 20.5+/- 0.7%. The calculated mineral content of the FFBM was 6.4%. These values are strikingly similar to the values calculated by direct chemical analysis. It was concluded that the combined TBN-TBK method is a valid technique for estimating body composition in man.

  18. The relationship between body composition, anaerobic performance and sprint ability of amputee soccer players.

    PubMed

    Ozkan, Ali; Kayıhan, Gürhan; Köklü, Yusuf; Ergun, Nevin; Koz, Mitat; Ersöz, Gülfem; Dellal, Alexandre

    2012-12-01

    The purpose of the present study was to investigate the relationship between body composition, anaerobic performance and sprint performance of amputee soccer players. Fifteen amputee soccer players participated in this study voluntarily. Subjects' height, body weight, body mass index, body fat percentage (Jackson and Pollock formula) and somatotype characteristics (Heath-Carter system) were determined. The sprint performance at 10m, 20m and 30m was evaluated, whereas the counter movement jump (CMJ), relative CMJ (RCMJ), squat jump (SJ) and relative SJ (RSJ) tests were used for the determination of anaerobic performance. The results of the Pearson Product Moment correlation analysis indicated that body composition was significantly correlated with CMJ and SJ (p < 0.01), on the other hand, no measure of body composition was significantly related to the other component (p > 0.05). A significant correlation was found between CMJ, RCMJ, SJ, 10 m, 20 m and 30 m sprint performance (p < 0.05); whereas, in contrast, no measure of body composition was significantly related to the 10 m, 20 m and 30 m sprint performance (p > 0.05). In conclusion, the findings of the present study indicated that sprint performance was described as an essential factor in anaerobic performance whereas body composition and somatotype play a determinant role in anaerobic and sprint performance in amputee soccer players.

  19. The Relationship Between Body Composition, Anaerobic Performance and Sprint Ability of Amputee Soccer Players

    PubMed Central

    Özkan, Ali; Kayıhan, Gürhan; Köklü, Yusuf; Ergun, Nevin; Koz, Mitat; Ersöz, Gülfem; Dellal, Alexandre

    2012-01-01

    The purpose of the present study was to investigate the relationship between body composition, anaerobic performance and sprint performance of amputee soccer players. Fifteen amputee soccer players participated in this study voluntarily. Subjects’ height, body weight, body mass index, body fat percentage (Jackson and Pollock formula) and somatotype characteristics (Heath-Carter system) were determined. The sprint performance at 10m, 20m and 30m was evaluated, whereas the counter movement jump (CMJ), relative CMJ (RCMJ), squat jump (SJ) and relative SJ (RSJ) tests were used for the determination of anaerobic performance. The results of the Pearson Product Moment correlation analysis indicated that body composition was significantly correlated with CMJ and SJ (p < 0.01), on the other hand, no measure of body composition was significantly related to the other component (p > 0.05). A significant correlation was found between CMJ, RCMJ, SJ, 10 m, 20 m and 30 m sprint performance (p < 0.05); whereas, in contrast, no measure of body composition was significantly related to the 10 m, 20 m and 30 m sprint performance (p > 0.05). In conclusion, the findings of the present study indicated that sprint performance was described as an essential factor in anaerobic performance whereas body composition and somatotype play a determinant role in anaerobic and sprint performance in amputee soccer players. PMID:23486067

  20. Effects of participation in a collegiate sport season on body composition.

    PubMed

    Siders, W A; Bolonchuk, W W; Lukaski, H C

    1991-12-01

    Fifty-three collegiate athletes (18 female and 35 male) were recruited from university varsity basketball, football, swim, and wrestling team rosters. Body composition was estimated before the beginning and before the end of sport seasons by using hydrodensitometry to determine the effect of participation in competitive sport seasons on the body composition of collegiate athletes. ANOVAs applied to the estimates of body composition indicated that the interaction of sport team by season was significant for body weight, F (5,47) = 3.2, p less than 0.05; fat weight, F (5,47) = 5.1, p less than 0.01; and fat-free weight, F (5,47) = 2.4, p less than 0.05. Only football players did not change in body composition. Wrestlers lost the greatest amount of body weight (3.4 kg). Female and male basketball players, female and male swimmers, and wrestlers lost significant amounts of body fat (2.6, 2.3, 1.8, 2.7, and 3.6 kg, respectively). Female and male basketball players and female and male swimmers gained significant amounts of fat-free weight (2.0, 1.6, 2.4, and 1.8 kg, respectively). It was concluded that participation in a collegiate sport season could affect changes in fat weight and fat-free weight components of body composition but that the nature of the changes are a function of the demands of the sport of participation.

  1. Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride, carbide and carbonitride

    DOEpatents

    Wong, Ming-Show; Li, Dong; Chung, Yip-Wah; Sproul, William D.; Chu, Xi; Barnett, Scott A.

    1998-01-01

    A composite material having high hardness comprises a carbon nitrogen compound, such as CN.sub.x where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN.sub.x. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45-55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating.

  2. Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride, carbide and carbonitride

    DOEpatents

    Wong, M.S.; Li, D.; Chung, Y.W.; Sproul, W.D.; Chu, X.; Barnett, S.A.

    1998-07-07

    A composite material having high hardness comprises a carbon nitrogen compound, such as CN{sub x} where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN{sub x}. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45--55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating. 10 figs.

  3. Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride carbide and carbonitride

    DOEpatents

    Wong, Ming-Show; Li, Dong; Chung, Yin-Wah; Sproul, William D.; Chu, Xi; Barnett, Scott A.

    1998-01-01

    A composite material having high hardness comprises a carbon nitrogen compound, such as CN.sub.x where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN.sub.x. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45-55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating.

  4. Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride carbide and carbonitride

    DOEpatents

    Wong, M.S.; Li, D.; Chung, Y.W.; Sproul, W.D.; Xi Chu; Barnett, S.A.

    1998-03-10

    A composite material having high hardness comprises a carbon nitrogen compound, such as CN{sub x} where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN{sub x}. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45--55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating. 10 figs.

  5. Structure and composition of zirconium carbide thin-film grown by ion beam sputtering for optical applications

    NASA Astrophysics Data System (ADS)

    Singh, Amol; Modi, Mohammed H.; Dhawan, Rajnish; Lodha, G. S.

    2014-04-01

    Thin film of compound material ZrC was deposited on Si (100) wafer using ion beam sputtering method. The deposition was carried out at room temperature and at base pressure of 3×10-5 Pa. X-ray photoelectron spectroscopy (XPS) measurements were performed for determining the surface chemical compositions. Grazing incidence x-ray reflectivity (GIXRR) measurements were performed to study the film thickness, roughness and density. From GIXRR curve roughness value of the film was found less than 1 nm indicating smooth surface morphology. Films density was found 6.51 g/cm3, which is close to bulk density. Atomic force microscopy (AFM) measurements were performed to check the surface morphology. AFM investigation showed that the film surface is smooth, which corroborate the GIXRR data. Figure 2 of the original article PDF file, as supplied to AIP Publishing, contained a PDF processing error. This article was updated on 12 May 2014 to correct that error.

  6. Sodium sulfate corrosion of silicon carbide fiber-reinforced lithium aluminosilicate glass-ceramic matrix composites. Master's thesis

    SciTech Connect

    Maldia, L.C.

    1993-12-01

    Sodium sulfate hot corrosion of a SiC fiber-reinforced lithium aluminosilicate (LAS) glass-ceramic matrix composite was studied using Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). Changes in the microstructural chemical composition of the specimens were investigated. The samples provided by Naval Air Warfare Center (NAWC), Warminster, PA were grouped as follows: (1) as-received, (2) Na2SO4 salt-coated and heat-treated in oxygen, (3) noncoated and heat-treated in oxygen, (4) Na2SO4. Salt-coated and heat-treated in argon, and (5) noncoated and heat-treated in argon. Heat treatment was performed by NAWC for 100 hours at 900 deg C. Experimental data obtained indicated that the presence of Na2SO4 in an oxidative environment resulted in rapid corrosion of the matrix and SiC fibers and in the latter rings of SiO2 replaced what had previously been SiC. There was very limited degradation of the fibers and matrix exposed at the surface in the noncoated sample heat-treated in oxygen and in the salt-coated sample heat-treated in argon. A significant reduction in the amount of mullite in the matrices of all heat-treated samples was observed. Mullite dissolved into either the glassy phase or into the Beta-spodumene matrix. Lastly, the presence of distinct magnesium silicate crystalline phases in the salt-coated and heat-treated in oxygen sample implies that the MgO at the surface reacted with the SiO2 in the matrix.

  7. Dynamics of body protein deposition and changes in body composition after sudden changes in amino acid intake: I. Barrows.

    PubMed

    Martínez-Ramírez, H R; Jeaurond, E A; de Lange, C F M

    2008-09-01

    A study was conducted to evaluate the extent and dynamics of whole body protein deposition and changes in chemical and physical body composition after a period of AA intake restriction in growing barrows with medium lean tissue growth potentials. Forty Yorkshire barrows (initial BW 14.4 +/- 1.6 kg) were scale-fed at 75% of estimated voluntary daily DE intake up to 35 kg of BW and assigned to 1 of 2 diets: AA adequate (AA+; 20% above requirements; NRC, 1998) and AA deficient (AA-; 40% below requirements; restriction phase). Thereafter (re-alimentation phase), pigs from both dietary AA levels were scale-fed or fed ad libitum diets that were not limiting in AA. Body weight gain and body composition, based on serial slaughter, were monitored during the 34-d re-alimentation phase. During the restriction phase AA intake restriction reduced BW gains (556 vs. 410 g/d; P < 0.001; AA+ and AA-, respectively). At 35 kg of BW, AA intake restriction increased whole body lipid content (11.1 vs. 17.5% of empty BW; P < 0.05) and the whole body lipid to body protein ratio (0.65 vs. 1.20; P < 0.01) and reduced body protein content (17.1 vs. 14.6% of empty BW; P < 0.01) and body water content (68.2 vs. 63.9%; P < 0.05). The relationships between body protein vs. body water and body protein vs. body ash content were not altered by previous AA intake restriction or by feeding level during the re-alimentation phase (P > 0.10). Throughout the re-alimentation phase, there were no interactive effects of time, feeding level, and previous AA intake level on growth performance, body protein, and body lipid content (P > 0.10). During the re-alimentation phase, body protein deposition, derived from the linear regression analysis of body protein content vs. time, was not affected by feeding level and previous AA intake level (P > 0.10; 156 g/d for AA- vs. 157 g/d for AA+). Based on BW and body protein content, it can be concluded that no compensatory body protein deposition occurred in barrows

  8. Body image and correlation with body composition and attrition rate in the TIGER study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Body image can be a very important part of determining an individual's outlook and behavior. Previous research has shown that the degree of satisfaction women have with their bodies may vary across race and may have a significant impact on an individual's motivation and commitment to a regular exer...

  9. Genetic influences on growth and body composition in mice: multilocus interactions

    PubMed Central

    Ankra-Badu, Georgina A.; Pomp, Daniel; Shriner, Daniel; Allison, David B.; Yi, Nengjun

    2011-01-01

    Background The genetic architecture of body weight and body composition is complex because these traits are normally influenced by multiple genes and their interactions, even after controlling for the environment. Bayesian methodology provides an efficient way of estimating these interactions. Subjects and measurements We used Bayesian model selection techniques to estimate the effect of epistatic interactions on age-related body weight (at 3, 6, and 10 weeks) and body composition (organ weights and fat-related traits) in an F2 sample obtained from a cross between high-growth (M16i) mice and low-growth (L6) mice. Results We observed epistatic and main-effect quantitative trait loci (QTL) that controlled both body weight and body composition. Epistatic effects were generally more significant for WK3 and WK6 than WK10. Chromosomes 5 and 13 interacted strongly to control body weight at 3 weeks. A pleiotropic QTL on chromosome 2 was associated with body weight and some body composition phenotypes. Testis weight was regulated by a QTL on chromosome 13 with a significantly large main effect. Conclusion By analyzing epistatic interactions, we detected QTL not found in a previous analysis of this mouse population. Hence, the detection of gene-gene interactions may provide new information about the genetic architecture of complex obesity-related traits and may lead to the detection of additional obesity genes. PMID:18982013

  10. The Evaluation of a Circumference-based Prediction Equation to Assess Body Composition Changes in Men

    PubMed Central

    SCHUNA, JOHN M.; HILGERS, SARAH J.; MANIKOWSKE, TRISTA L.; TUCKER, JARED M.; LIGUORI, GARY

    2013-01-01

    This study evaluated the validity of the current U.S. Department of Defense (DOD) circumference-based prediction equation for males to detect body composition changes in comparison to air-displacement plethysmography (ADP). Body composition was assessed using ADP and the DOD equation at the beginning and end of an academic school year among 21 male (18–29 years-old) Army ROTC cadets. Body mass significantly increased (+1.8 Kg) after 9 months. Significant method by time interactions for percent body fat (percent body fat), fat mass (FM), and fat-free mass were found (p = 0.022, p = 0.023, p = 0.023, respectively) as body composition changes were not tracked equally by the two methods. Regression and Bland-Altman analyses indicated a lack of agreement between methods as the DOD equation underestimated percent body fat and FM changes in comparison to ADP. Results suggest the DOD equation for males cannot adequately detect body composition changes following a small body mass gain. PMID:27182395

  11. Validation of bioelectrical-impedance analysis as a measurement of change in body composition in obesity

    SciTech Connect

    Kushner, R.F.; Kunigk, A.; Alspaugh, M.; Andronis, P.T.; Leitch, C.A.; Schoeller, D.A. )

    1990-08-01

    The bioelectrical-impedance-analysis (BIA) method accurately measures body composition in weight-stable subjects. This study validates the use of BIA to measure change in body composition. Twelve obese females underwent weight loss at a mean rate of 1.16 kg/wk. Body composition was measured by deuterium oxide dilution (D2O), BIA, and skinfold anthropometry (SFA) at baseline and at 5% decrements in weight. Highly significant correlations were obtained between D2O and BIA (r = 0.971) and between D2O and SFA (r = 0.932). Overall, BIA predicted change in fat-free mass with greater accuracy (to 0.4 kg) and precision (+/- 1.28 kg) than did anthropometry (to 0.8 kg and +/- 2.58 kg, respectively). We conclude that BIA is a useful clinical method for measuring change in body composition.

  12. International symposium on in vivo body composition studies: Program and abstracts

    SciTech Connect

    Not Available

    1986-01-01

    This booklet contains the program and individual abstracts for papers presented at the International symposium on in vivo body composition studies. The presentations were divided into five sessions. Individual abstracts were indexed for the Energy Data Base. (DT)

  13. Effects on body size and composition of chronic exposure to altered gravity. [centrifuging stress in mammals

    NASA Technical Reports Server (NTRS)

    Pitts, G. C.

    1977-01-01

    The effects of chronic centrifugation on body composition and growth of rats, mice, monkeys, and man are studied. The benefits of exercise and restraint during acceleration are investigated. Physiological regulation and energy balance are also discussed.

  14. Body Composition and Anthropometric Correlates of Isokinetic Leg Extension Strength of Young Adult Males.

    ERIC Educational Resources Information Center

    Nutter, June; Thorland, William G.

    1987-01-01

    This study examined the relative importance of body size and composition as determinants of differences in isokinetic leg extensor strength in young adult males performing at slow, moderate, and fast speeds. Results are discussed. (Author/MT)

  15. Liquid phase sintering of silicon carbide

    DOEpatents

    Cutler, R.A.; Virkar, A.V.; Hurford, A.C.

    1989-05-09

    Liquid phase sintering is used to densify silicon carbide based ceramics using a compound comprising a rare earth oxide and aluminum oxide to form liquids at temperatures in excess of 1,600 C. The resulting sintered ceramic body has a density greater than 95% of its theoretical density and hardness in excess of 23 GPa. Boron and carbon are not needed to promote densification and silicon carbide powder with an average particle size of greater than one micron can be densified via the liquid phase process. The sintered ceramic bodies made by the present invention are fine grained and have secondary phases resulting from the liquid phase. 4 figs.

  16. Liquid phase sintering of silicon carbide

    DOEpatents

    Cutler, Raymond A.; Virkar, Anil V.; Hurford, Andrew C.

    1989-01-01

    Liquid phase sintering is used to densify silicon carbide based ceramics using a compound comprising a rare earth oxide and aluminum oxide to form liquids at temperatures in excess of 1600.degree. C. The resulting sintered ceramic body has a density greater than 95% of its theoretical density and hardness in excess of 23 GPa. Boron and carbon are not needed to promote densification and silicon carbide powder with an average particle size of greater than one micron can be densified via the liquid phase process. The sintered ceramic bodies made by the present invention are fine grained and have secondary phases resulting from the liquid phase.

  17. A new air displacement plethysmograph for the determination of Japanese body composition.

    PubMed

    Miyatake, N; Nonaka, K; Fujii, M

    1999-11-01

    A new device based on the plethysmographic measurement of body volume, named the BOD POD Body Composition System, was developed for the purpose of estimating body composition. The performance, reliability, validity, and clinical application of this system were evaluated in Japanese subjects. The coefficient variation (CV:%) in same-day tests was 2.48, in three separate-day tests it was 2.27, and for independent operators it was 4.53, respectively. There was a clear correlation between the results from BOD POD and those from dual energy X-ray absorptiometry (DEXA) (r = 0.910, p < 0.01). Finally, the fat body composition of 4489 subjects (1499 men, 2990 women) was clinically measured by BOD POD. The findings indicate that the BOD POD is a highly reliable and valid method for determining body fat percentage. This new method has several advantages, e.g. it is quick, simple to operate and may accommodate wide populations.

  18. Method of making a composite refractory material

    DOEpatents

    Morrow, Marvin S.; Holcombe, Cressie E.

    1995-01-01

    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.

  19. Gelcasting of CRYSTAR{reg_sign} silicon carbide ceramics. CRADA final report

    SciTech Connect

    Nunn, S.D.; Willkens, C.A.

    1998-12-31

    This Cooperative Research and Development Agreement (CRADA) was undertaken to assess the applicability the gelcasting process for forming ceramic green bodies using Saint-Gobain/Norton Industrial Ceramics Corporation`s proprietary CRYSTAR{reg_sign} silicon carbide powder. A gelcasting process, specifically tailored to Saint-Gobain/Norton`s powder composition, was developed and used successfully to form green bodies for property evaluation. This preliminary evaluation showed that the gelcast material had characteristics and properties comparable to Norton`s baseline material. Wafer carrier molds were received from Norton for gelcasting a complex-shaped configuration with CRYSTAR{reg_sign} silicon carbide. Gelcasting experiments showed that Norton`s standard plaster of paris molds were incompatible with the gelcasting process. Mold surface treatments and the use of alternative castable mold materials were investigated, however, a successful process was not identified. The highest quality parts were cast in either glass or aluminum molds.

  20. Dual-energy X-ray absorptiometry body composition in patients with secondary osteoporosis.

    PubMed

    Messina, Carmelo; Monaco, Cristian Giuseppe; Ulivieri, Fabio Massimo; Sardanelli, Francesco; Sconfienza, Luca Maria

    2016-08-01

    Due to the tight relationship between bone and soft tissues, there has been an increased interest in body composition assessment in patients with secondary osteoporosis as well as other pathological conditions. Dual-energy X-ray absorptiometry (DXA) is primarily devoted to the evaluation of bone mineral status, but continuous scientific advances of body composition software made DXA a rapid and easily available technique to assess body composition in terms of fat mass and lean mass. As a result, the International Society for Clinical Densitometry (ISCD) recently developed Official Positions regarding the use of this technique for body composition analysis. According to ISCD paper, indications are mainly limited to three conditions: HIV patients treated with antiretroviral agents associated with a risk of lipoatrophy; obese patients undergoing treatment for high weight loss; patients with sarcopenia or muscle weakness. Nevertheless, there are several other interesting clinical applications that were not included in the ISCD position paper, such as body composition assessment in patients undergoing organ transplantation, pulmonary disease as well as all those chronic condition that may lead to malnutrition. In conclusion, DXA body composition offers new diagnostic and research possibilities for a variety of diseases; due to its high reproducibility, DXA has also the potential to monitor body composition changes with pharmacological, nutritional or physic therapeutic interventions. ISCD addressed and recommended a list of clinical condition, but the crescent availability of DXA scans and software improvements may open the use of DXA to other indication in the next future. This article provides an overview of DXA body composition indications in the management of secondary osteoporosis and other clinical indications in adults. PMID:27048946

  1. [Anorexia nervosa: bioelectrical impedance analysis in body composition measurement during hospitalization].

    PubMed

    Van Leer, M; Leistedt, S J; Linkowski, P; Simon, Y

    2013-01-01

    Monitoring parameters for anorexia nervosa include clinical, biological and psychological factors. Many research groups are currently trying to identify parameters more likely to predict the severity or the evolution of the illness. Body composition has been proposed as one of those parameters. The aim of the present study is to demonstrate that measures of body composition are more accurate and efficient than the use of body composition index (BMI). We also aim to show that body composition could be used as a prognostic factor in the long-term evolution of patients with anorexia nervosa. It's a retrospective study investigating body composition and BMI in 44 patients treated in a specialized unit for eating disorder. Measures of body composition and BMI were gathered at the time of admission and again 3 months after refeeding onset. Data was correlated to the EDI-2 questionnaire scores. BMI and %FM where found to be increased (P < 0.05) between admission and after 3 months refeeding. The double objective of reaching a BMI value > or = 20 kg/m2 and a %FM value > or = 2% was achieved by 22% of patients. No significant correlation was found between EDI-2 scores and measures of BMI and %FM either on admission or after the 3 months refeeding period. In conclusion, results of our study don't allow concluding for a prognostic superiority of %FM. Nonetheless, BMI currently used as a reference for the monitoring of eating disorders patients seems to lack sensitivity where measures of body composition seem more informative regarding nutritional status. Furthermore, fat mass plays an important role in other clinical manifestations. In addition, measures of body composition should allow more individualised therapeutic support.

  2. Body composition and arsenic metabolism: a cross-sectional analysis in the Strong Heart Study

    PubMed Central

    2013-01-01

    Objective The objective of this study was to evaluate the association between measures of body composition and patterns of urine arsenic metabolites in the 1989–1991 baseline visit of the Strong Heart Study, a cardiovascular disease cohort of adults recruited from rural communities in Arizona, Oklahoma, North Dakota and South Dakota. Methods We evaluated 3,663 Strong Heart Study participants with urine arsenic species above the limit of detection and no missing data on body mass index, % body fat and fat free mass measured by bioelectrical impedance, waist circumference and other variables. We summarized urine arsenic species patterns as the relative contribution of inorganic (iAs), methylarsonate (MMA) and dimethylarsinate (DMA) species to their sum. We modeled the associations of % arsenic species biomarkers with body mass index, % body fat, fat free mass, and waist circumference categories in unadjusted regression models and in models including all measures of body composition. We also considered adjustment for arsenic exposure and demographics. Results Increasing body mass index was associated with higher mean % DMA and lower mean % MMA before and after adjustment for sociodemographic variables, arsenic exposure, and for other measures of body composition. In unadjusted linear regression models, % DMA was 2.4 (2.1, 2.6) % higher per increase in body mass index category (< 25, ≥25 & <30, ≥30 & <35, ≥35 kg/m2), and % MMA was 1.6 (1.4, 1.7) % lower. Similar patterns were observed for % body fat, fat free mass, and waist circumference measures in unadjusted models and in models adjusted for potential confounders, but the associations were largely attenuated or disappeared when adjusted for body mass index. Conclusion Measures of body size, especially body mass index, are associated with arsenic metabolism biomarkers. The association may be related to adiposity, fat free mass or body size. Future epidemiologic studies of arsenic should consider body mass

  3. Validation of body composition models for high school wrestlers.

    PubMed

    Williford, H N; Smith, J F; Mansfield, E R; Conerly, M D; Bishop, P A

    1986-04-01

    This study investigates the utility of two equations for predicting minimum wrestling weight and three equations for predicting body density for the population of high school wrestlers. A sample of 54 wrestlers was assessed for body density by underwater weighing, residual volume by helium dilution, and selected anthropometric measures. The differences between observed and predicted responses were analyzed for the five models. Four statistical tests were used to validate the equations, including tests for the mean of differences, proportion of positive differences, equality of standard errors from regression, and equivalence of regression coefficients between original and second sample data. The Michael and Katch equation and two Forsyth and Sinning equations (FS1 and FS21) for body density did not predict as well as expected. The Michael and Katch equation tends to overpredict body density while FS1 underpredicts. The FS2 equation, consisting of a constant adjustment to FS1, predicts well near the mean but not at the ends of the sample range. The two Tcheng and Tipton equations produce estimates which slightly but consistently overpredict minimum wrestling weight, the long form equation by 2.5 pounds and the short form by 3.8 pounds. As a result the proportion of positive differences is less than would be expected. But based on the tests for the standard errors and regression coefficients, the evidence does not uniformly reject these two equations.

  4. Effect of physical activity intervention on body composition in young children: influence of body mass index status and gender

    PubMed Central

    Lazaar, Nordine; Aucouturier, Julien; Ratel, Sébastien; Rance, Mélanie; Meyer, Martine; Duché, Pascale

    2007-01-01

    Aim To fight overweight and obesity in childhood, this study proposes an additional physical activity (PA) in young children aged 6–10 years. The objective was to evaluate the effect of school-based PA on the body composition according to body mass index (BMI) categories (nonobese vs. obese) and gender. Methods This 6-month study examined the effect of this intervention on body composition in 425 children in 14 primary schools (2 weekly PA sessions of 1 h each) compared to 5 control schools. Adiposity indices were evaluated or calculated: BMI, BMI z-score, waist circumference, sum of skinfolds and fat-free mass. Results No difference in the prevalence of obesity and anthropometric characteristics was found between the intervention and control groups at baseline. In girls, PA intervention had significant effect on all anthropometric variables (p < 0.05 to p < 0.001), except on BMI. In contrast, in boys only BMI z-score (p < 0.001) and fat-free mass (p < 0.001) were affected. Conclusions Six months of preventive PA intervention offer an effective means to improve body composition in obese children. The pattern of response related to PA was similar between girls and boys. In contrast, the pattern was different according to BMI category, with a higher response in obese than nonobese children. PMID:17718785

  5. Brazed boron-silicon carbide/aluminum structural panels

    NASA Technical Reports Server (NTRS)

    Arnold, W. E., Jr.; Bales, T. T.; Brooks, T. G.; Lawson, A. G.; Mitchell, P. D.; Royster, D. M.; Wiant, R.

    1978-01-01

    Fluxless brazing process minimizes degradation of mechanical properties composite material of silicon carbide coated boron fibers in an aluminum matrix. Process is being used to fabricate full-scale Boron-Silicon Carbide/Aluminum-Titanium honeycomb core panels for flight testing and ground testing.

  6. The chemical vapor deposition of zirconium carbide onto ceramic substrates

    SciTech Connect

    Glass, John A, Jr.; Palmisiano, Nick, Jr.; Welsh, R. Edward

    1999-07-01

    Zirconium carbide is an attractive ceramic material due to its unique properties such as high melting point, good thermal conductivity, and chemical resistance. The controlled preparation of zirconium carbide films of superstoichiometric, stoichiometric, and substoichiometric compositions has been achieved utilizing zirconium tetrachloride and methane precursor gases in an atmospheric pressure high temperature chemical vapor deposition system.

  7. Body composition in elderly persons: a critical review of needs and methods.

    PubMed

    Baumgartner, R N

    1993-01-01

    Significant changes in body composition that have important health related effects are believed to occur in the elderly. Knowledge of these changes is important for diagnoses, prognoses, and treatment of health problems. Many health problems in the elderly could be prevented or alleviated by nutritional modulation, but better understanding of the nature, extent, and underlying physiology of body compositional changes is needed for such interventions to be successful. There are currently few data for body composition in the elderly, especially for those greater than 75 y in age, partly because conventional methods of assessing body composition are difficult to apply for technical and conceptual reasons. As a result, little is known regarding the relationships of body composition to nutritional, functional or health status in non-hospitalized, free-living elderly persons. Knowledge of the "natural history" of body compositional changes and their relationships to other nutritional and health factors could lead to new insights on prevention and treatment, the reduction of morbidity and extension of the quality of life of older persons. PMID:8234779

  8. Electrical acupoint stimulation changes body composition and the meridian systems in postmenopausal women with obesity.

    PubMed

    Lin, Chia-Hsien; Lin, Yu-Min; Liu, Chi-Feng

    2010-01-01

    This study evaluates the effects of electrical stimulation on body composition and the meridian system in postmenopausal women with obesity. Forty-one postmenopausal women were recruited in Taiwan. The body composition was used as a screening test for obesity (percentage of body fat: > 30%, waist circumference: > 80 cm). The experimental group (EG, n = 20) received modulated middle-frequency electrical stimulation treatment for 20 min twice a week for 12 consecutive weeks at the Zusanli (ST36) and Sanyinjiao (SP6) acupoints. The control group (CG, n = 21) did not receive any intervention. The measurements of body composition and the meridian system were recorded for both groups in the pre- and post-study. The results showed that the data of body composition (weight, waist and hip circumference, percentage of body fat, and percentage of lean muscle mass) changed considerably in the EG (p < 0.05); however, no significant difference was observed in the CG. The left triple burner meridian changed notably in both EG and CG throughout the study (p < 0.05), however there was no difference between the two groups in the overall mean value, up-down ratio, qi and blood ratio, and yin-yang ratio. Our findings suggest that modulated middle-frequency electrical stimulation could help to improve body composition in postmenopausal women with obesity, potentially providing them with better care and health by integrating Western medicine and traditional Chinese medicine.

  9. Physical training improves body composition of black obese 7- to 11-year-old girls.

    PubMed

    Gutin, B; Cucuzzo, N; Islam, S; Smith, C; Moffatt, R; Pargman, D

    1995-07-01

    We determined the effect of supervised physical training without dietary intervention, on body composition of obese girls. The subjects were 25 obese 7- to 11-year-old black girls, divided into physical training and lifestyle education groups which were comparable on baseline body composition; 22 girls finished all aspects of the study. Twelve girls engaged in aerobic training (10 weeks, 5 days/week) while 10 engaged in weekly lifestyle discussions without formal physical training. Total body and regional body composition were measured with dual energy x-ray absorptiometry, skinfolds and circumferences. Aerobic fitness was measured by heart rate response to submaximal treadmill exercise. The physical training group attended 94% of scheduled sessions and kept their heart rates at an average of 163 bpm for 28 minutes/session. The lifestyle group attended 95% of their sessions; they remained stable in aerobic fitness and most body composition measurements. The physical training group showed a significant improvement in aerobic fitness and a significant decline of 1.4% body fat. Skinfold and circumference indices of fatness also declined significantly in the training group. We conclude that controlled physical training, without dietary intervention, improved the fitness and body composition of obese black girls.

  10. Barium Isotopic Composition of Mainstream Silicon Carbides from Murchison: Constraints for s-process Nucleosynthesis in Asymptotic Giant Branch Stars

    NASA Astrophysics Data System (ADS)

    Liu, Nan; Savina, Michael R.; Davis, Andrew M.; Gallino, Roberto; Straniero, Oscar; Gyngard, Frank; Pellin, Michael J.; Willingham, David G.; Dauphas, Nicolas; Pignatari, Marco; Bisterzo, Sara; Cristallo, Sergio; Herwig, Falk

    2014-05-01

    We present barium, carbon, and silicon isotopic compositions of 38 acid-cleaned presolar SiC grains from Murchison. Comparison with previous data shows that acid washing is highly effective in removing barium contamination. Strong depletions in δ(138Ba/136Ba) values are found, down to -400‰, which can only be modeled with a flatter 13C profile within the 13C pocket than is normally used. The dependence of δ(138Ba/136Ba) predictions on the distribution of 13C within the pocket in asymptotic giant branch (AGB) models allows us to probe the 13C profile within the 13C pocket and the pocket mass in AGB stars. In addition, we provide constraints on the 22Ne(α, n)25Mg rate in the stellar temperature regime relevant to AGB stars, based on δ(134Ba/136Ba) values of mainstream grains. We found two nominally mainstream grains with strongly negative δ(134Ba/136Ba) values that cannot be explained by any of the current AGB model calculations. Instead, such negative values are consistent with the intermediate neutron capture process (i process), which is activated by the very late thermal pulse during the post-AGB phase and characterized by a neutron density much higher than the s process. These two grains may have condensed around post-AGB stars. Finally, we report abundances of two p-process isotopes, 130Ba and 132Ba, in single SiC grains. These isotopes are destroyed in the s process in AGB stars. By comparing their abundances with respect to that of 135Ba, we conclude that there is no measurable decay of 135Cs (t 1/2 = 2.3 Ma) to 135Ba in individual SiC grains, indicating condensation of barium, but not cesium into SiC grains before 135Cs decayed.

  11. Body composition and phase angle in Russian children in remission from acute lymphoblastic leukemia

    NASA Astrophysics Data System (ADS)

    Tseytlin, G. Ja; Khomyakova, I. A.; Nikolaev, D. V.; Konovalova, M. V.; Vashura, A. Yu; Tretyak, A. V.; Godina, E. Z.; Rudnev, S. G.

    2010-04-01

    Elevated degree of body fatness and changes in other body composition parameters are known to be common effects of treatment for acute lymphoblastic leukemia (ALL) in children. In order to study peculiarities of somatic growth and development in ALL survivors, we describe the results of BIA body composition analysis of 112 boys and 108 girls aged 5-18 years in remission from ALL (remission time range 1-13 years) compared to data from the same number of age- and sex-matched healthy controls (n=220). Detrimental effect on height in ALL boys was observed, whereas girls experienced additional weight gain compared to healthy subjects. In ALL patients, resistance, body fat, and percent body fat were significantly increased. The reactance, phase angle, absolute and relative values of skeletal muscle and body cell mass were significantly decreased. Principal component analysis revealed an early prevalence of adiposity traits in the somatic growth and development of ALL girls compared to healthy controls.

  12. Body composition of active persons with spinal cord injury and with poliomyelitis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study sought to evaluate the body composition of subjects with active spinal cord injuries and polio. Two groups of males and females, active, free-living, of similar ages and body mass index (BMI), were distributed according to the source of deficiency: SCI – low spinal cord injury (T5-T12) an...

  13. Effects of change in body composition on gene expression in the uterine endometrium of beef cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to determine the impact of change of body composition on gene expression in the uterine endometrium of beef cows. Mature, non-lactating Angus cows (body condition score [BCS] = 5.07 ± 0.1) were fed a similar diet for 30 d prior to the initiation of the study. Follow...

  14. Psychosocial Variables Associated with Body Composition and Cardiorespiratory Fitness in Middle School Students

    ERIC Educational Resources Information Center

    Greenleaf, Christy A.; Petrie, Trent A.; Martin, Scott B.

    2010-01-01

    This study examined the associations among self-esteem, depression, physical self-concept, and body satisfaction among 1,022 middle school students who were in the FITNESSGRAM[R] Healthy Fitness Zone[TM] (HFZ) compared to those in the Needs Improvement Zone (NIZ) for body composition and cardiorespiratory fitness. After controlling for…

  15. Holistic processing of human body postures: evidence from the composite effect.

    PubMed

    Willems, Sam; Vrancken, Leia; Germeys, Filip; Verfaillie, Karl

    2014-01-01

    The perception of socially relevant stimuli (e.g., faces and bodies) has received considerable attention in the vision science community. It is now widely accepted that human faces are processed holistically and not only analytically. One observation that has been taken as evidence for holistic face processing is the face composite effect: two identical top halves of a face tend to be perceived as being different when combined with different bottom halves. This supports the hypothesis that face processing proceeds holistically. Indeed, the interference effect disappears when the two face parts are misaligned (blocking holistic perception). In the present study, we investigated whether there is also a composite effect for the perception of body postures: are two identical body halves perceived as being in different poses when the irrelevant body halves differ from each other? Both a horizontal (i.e., top-bottom body halves; Experiment 1) and a vertical composite effect (i.e., left-right body halves; Experiment 2) were examined by means of a delayed matching-to-sample task. Results of both experiments indicate the existence of a body posture composite effect. This provides evidence for the hypothesis that body postures, as faces, are processed holistically.

  16. Body Composition and Aerobic Requirements of Male and Female Marathon Runners.

    ERIC Educational Resources Information Center

    Wells, Christine L.; And Others

    This study investigates the physical characteristics, body composition, cardiovascular and pulmonary functions, and aerobic capabilities of male and female long distance runners. Eleven runners volunteered to take tests to determine background information, body fat, oxygen uptake, and running time and pace. Conclusions made from this study…

  17. The Relationship between Selected Body Composition Variables and Muscular Endurance in Women

    ERIC Educational Resources Information Center

    Esco, Michael R.; Olson, Michele S.; Williford, Henry N.

    2010-01-01

    The primary purpose of this study was to determine if muscular endurance is affected by referenced waist circumference groupings, independent of body mass and subcutaneous abdominal fat, in women. This study also explored whether selected body composition measures were associated with muscular endurance. Eighty-four women were measured for height,…

  18. Barium isotopic composition of mainstream silicon carbides from Murchison: Constraints for s-process nucleosynthesis in asymptotic giant branch stars

    SciTech Connect

    Liu, Nan; Davis, Andrew M.; Pellin, Michael J.; Dauphas, Nicolas; Savina, Michael R.; Gallino, Roberto; Bisterzo, Sara; Straniero, Oscar; Cristallo, Sergio; Gyngard, Frank; Willingham, David G.; Pignatari, Marco; Herwig, Falk

    2014-05-01

    We present barium, carbon, and silicon isotopic compositions of 38 acid-cleaned presolar SiC grains from Murchison. Comparison with previous data shows that acid washing is highly effective in removing barium contamination. Strong depletions in δ({sup 138}Ba/{sup 136}Ba) values are found, down to –400‰, which can only be modeled with a flatter {sup 13}C profile within the {sup 13}C pocket than is normally used. The dependence of δ({sup 138}Ba/{sup 136}Ba) predictions on the distribution of {sup 13}C within the pocket in asymptotic giant branch (AGB) models allows us to probe the {sup 13}C profile within the {sup 13}C pocket and the pocket mass in AGB stars. In addition, we provide constraints on the {sup 22}Ne(α, n){sup 25}Mg rate in the stellar temperature regime relevant to AGB stars, based on δ({sup 134}Ba/{sup 136}Ba) values of mainstream grains. We found two nominally mainstream grains with strongly negative δ({sup 134}Ba/{sup 136}Ba) values that cannot be explained by any of the current AGB model calculations. Instead, such negative values are consistent with the intermediate neutron capture process (i process), which is activated by the very late thermal pulse during the post-AGB phase and characterized by a neutron density much higher than the s process. These two grains may have condensed around post-AGB stars. Finally, we report abundances of two p-process isotopes, {sup 130}Ba and {sup 132}Ba, in single SiC grains. These isotopes are destroyed in the s process in AGB stars. By comparing their abundances with respect to that of {sup 135}Ba, we conclude that there is no measurable decay of {sup 135}Cs (t {sub 1/2} = 2.3 Ma) to {sup 135}Ba in individual SiC grains, indicating condensation of barium, but not cesium into SiC grains before {sup 135}Cs decayed.

  19. A DXA Whole Body Composition Cross-Calibration Experience: Evaluation With Humans, Spine, and Whole Body Phantoms.

    PubMed

    Krueger, Diane; Libber, Jessie; Sanfilippo, Jennifer; Yu, Hui Jing; Horvath, Blaine; Miller, Colin G; Binkley, Neil

    2016-01-01

    New densitometer installation requires cross-calibration for accurate longitudinal assessment. When replacing a unit with the same model, the International Society for Clinical Densitometry recommends cross-calibrating by scanning phantoms 10 times on each instrument and states that spine bone mineral density (BMD) should be within 1%, whereas total body lean, fat, and %fat mass should be within 2% of the prior instrument. However, there is limited validation that these recommendations provide adequate total body cross-calibration. Here, we report a total body cross-calibration experience with phantoms and humans. Cross-calibration between an existing and new Lunar iDXA was performed using 3 encapsulated spine phantoms (GE [GE Lunar, Madison, WI], BioClinica [BioClinica Inc, Princeton, NJ], and Hologic [Hologic Inc, Bedford, MA]), 1 total body composition phantom (BioClinica), and 30 human volunteers. Thirty scans of each phantom and a total body scan of human volunteers were obtained on each instrument. All spine phantom BMD means were similar (within 1%; <-0.010 g/cm2 bias) between the existing and new dual-energy X-ray absorptiometry unit. The BioClinica body composition phantom (BBCP) BMD and bone mineral content (BMC) values were within 2% with biases of 0.005 g/cm2 and -3.4 g. However, lean and fat mass and %fat differed by 4.6%-7.7% with biases of +463 g, -496 g, and -2.8%, respectively. In vivo comparison supported BBCP data; BMD and BMC were within ∼2%, but lean and fat mass and %fat differed from 1.6% to 4.9% with biases of +833 g, -860 g, and -1.1%. As all body composition comparisons exceeded the recommended 2%, the new densitometer was recalibrated. After recalibration, in vivo bias was lower (<0.05%) for lean and fat; -23 and -5 g, respectively. Similarly, BBCP lean and fat agreement improved. In conclusion, the BBCP behaves similarly, but not identical, to human in vivo measurements for densitometer cross-calibration. Spine phantoms, despite good

  20. Body composition and physical self-concept in older women.

    PubMed

    Shaw, J M; Ebbeck, V; Snow, C M

    2000-01-01

    We sought to determine the performance and anthropometric correlates of physical self-concept and self-esteem and to observe whether long-term resistance training would alter these variables in postmenopausal women. Forty-four nonsmoking, community-dwelling, Caucasian women aged 50-75 years participated in the study. Half of the subjects participated in a 9-month regimen of weight-bearing exercises performed 3 times per week which emphasized lower body muscle strength and power development. At baseline, total body fat was negatively associated with physical self-concept and perception of physical appearance but not with self-esteem. Perception of physical appearance improved in both exercisers and controls after the 9-month trial but was most noticeable in exercisers who had low self-esteem at baseline. The only predictor of improvement in perception of physical appearance was a decrease in lower body fat mass. Minimal or nonsignificant change in psychological measures associated with the training may be due to high initial values. PMID:11151355

  1. Do Canadian collegiate hockey players accurately perceive body composition changes after unmonitored training and diet?

    PubMed

    Prokop, Neal W; Duncan, Lindsay R; Andersen, Ross E

    2015-10-01

    Collegiate athletes often use nutritional programs and supplements to elicit body composition changes in muscle or fat. It is unknown if athletes can accurately perceive their fluctuations in body composition, yet their understanding may help them make more accurate interpretations regarding the success of potential nutrition or exercise regimens. The purpose of this study was to investigate if collegiate hockey players could accurately perceive a change in body composition during a 3-month period within their regular season, in which no predetermined nutritional or exercise program was provided. Twenty-four male Canadian collegiate hockey players completed preseason and midseason body composition assessments using dual-energy X-ray absorptiometry. Immediately before the midseason scan, players attempted to accurately match their perceived fluctuation in composition, with predetermined categorical ranges of relative body composition and strength. Two-thirds of players and one-half of players accurately perceived changes in arm-lean and arm-fat tissue, respectively. Approximately two-thirds of players did not accurately perceive gains or losses of lean or fat tissue within their leg and overall body. Although some athletes partially detected changes in the lean and fat tissue of particular regions, the vast majority of players cannot detect the type, or amount of tissue gained and lost across the overall body. Body composition assessments, rather than an athlete's perceptions, should be used to help interpret the success of a sport nutrition or exercise program. Athletes should be aware that physiologic adaptations might take place unnoticed, which could affect the acceptance and adherence of nutrition or exercise interventions. PMID:26394260

  2. Association Between Home Blood Pressure and Body Composition by Bioimpedance Monitoring in Patients Undergoing Peritoneal Dialysis.

    PubMed

    Kurasawa, Naho; Mori, Takefumi; Naganuma, Eri; Sato, Emiko; Koizumi, Kenji; Sato, Shinichi; Oba, Ikuko; Tsuchikawa, Mihoko; Ito, Sadayoshi

    2015-01-01

    Home blood pressure (HBP) is an independent predictor of cardiovascular and renal function. However, no particular guidelines have been established for optimal HBP in peritoneal dialysis (PD) patients. Bioelectrical impedance analysis (BIA) is a beneficial tool for determining body composition. In the present study, we used BIA to determine body composition parameters that might play a role in the regulation of HBP in PD patients, and we compared HBP with office blood pressure (BP). Our study enrolled 15 patients (11 men, 4 women) receiving PD at Tohoku University Hospital, who, for 1 year, agreed to monitor HBP and to undergo body composition analysis. Patients were requested to measure HBP twice daily (morning, night) using a home BP device. A bioimpedance monitor was used to monitor body composition each month. Blood and urine samples were also analyzed each month. The relationships of average morning systolic HBP (sMHBP) with parameters of body composition and of blood and urine analyses were evaluated. The enrolledpatients were 66.3 ± 7.7 years of age and had a PD vintage of 28.3 ± 6.4 months. Overall, their sMHBP was 128 ± 13 mmHg and their office systolic BP was 126 ± 15 mmHg. Although office systolic BP and sMHBP both correlated with body fluid parameters [total body water (TBW)/height2], renal function (renal Kt/V serum creatinine), and heart function (left ventricular mass index), the correlation coefficient for sMHBP and TBW/height2 was highest, with sMHBP being the only independent predictor. Sodium intake was associated only with sMHBP. Our results suggest that body fluid status determined by BIA, heart and renal function, and sodium intake show better associations with sMHBP than with office systolic BP. Monitoring HBP and body composition by BIA are beneficial for the maintenance of volume status in PD patients.

  3. Comparison of body composition in persons with epilepsy on conventional & new antiepileptic drugs

    PubMed Central

    Sarangi, Sudhir Chandra; Tripathi, Manjari; Kakkar, Ashish Kumar; Gupta, Yogendra Kumar

    2016-01-01

    Background & objectives: Certain antiepileptic drugs (AEDs) such as valproic acid (VPA) are known to affect body weight, and lipid profile. However, evidences regarding effects of AEDs on the body composition are deficient. This cross-sectional study compared the body composition and lipid profile among patients with epilepsy on newer and conventional AEDs. Methods: The patients with epilepsy (n=109) on treatment with conventional and newer AEDs (levetiracetam, lamotrigine and clobazam) for > 6 months were enrolled. Of these, 70 were on monotherapy: levetiracetam (n=12), VPA (n=16), carbamazepine (n=20) and phenytoin (n=22) and the remaining on polytherapy. Their body composition [body fat mass, lean dry mass (LDM), total body water (TBW), intracellular water (ICW), extracellular water (ECW) and basal metabolic rate (BMR) was estimated and biochemical parameters were assessed. Results: Levetiracetam group had no significant difference with VPA, carbamazepine, phenytoin and control groups, except low LDM (17.8±2.4) than VPA groups (20.2±2.7, P<0.05). In comparison with control, AEDs monotherapy groups had no significant difference, except higher LDM and ECW in VPA group. Among groups based on conventional and newer AEDs, there was no significant difference in body composition parameters except for higher LDM (as % of BW) in conventional AEDs only treated group than control (P<0.01). Interpretation & conclusions: The alterations observed in body composition with valproic acid in contrast to other AEDs like levetiracetam, carbamazepine and phenytoin could affect treatment response in epilepsy especially in subjects with already altered body composition status like obese and thin frail patients, which needs to be established by prospective studies (CTRI/2013/05/003701). PMID:27241646

  4. Methodology for estimation of total body composition in laboratory mammals

    NASA Technical Reports Server (NTRS)

    Pace, N.; Rahlmann, D. F.; Smith, A. H.

    1979-01-01

    A standardized dissection and chemical analysis procedure was developed for individual animals of several species in the size range mouse to monkey (15 g to 15 kg). The standardized procedure permits rigorous comparisons to be made both interspecifically and intraspecifically of organ weights and gross chemical composition in mammalian species series, and was applied successfully to laboratory mice, hamsters, rats, guinea pigs, and rabbits, as well as to macaque monkeys. The procedure is described in detail.

  5. Association between bone mineralization, body composition, and cardiorespiratory fitness level in young Australian men.

    PubMed

    Liberato, Selma Coelho; Maple-Brown, Louise; Bressan, Josefina

    2015-01-01

    The critical age for attainment of peak bone mineralization is however 20-30 yr, but few studies have investigated bone mineralization and its association with body composition and cardiorespiratory fitness level in young men. This study aimed to investigate relationships between age, bone mineral measurements, body composition measurements, and cardiorespiratory fitness level in a group of young healthy Australian men. Thirty-five healthy men aged 18-25 yr had anthropometric measures, body composition, and cardiorespiratory fitness level assessed. Bone mineral content was significantly associated with height, body mass and lean mass, and bone mineral density positively correlated with lean mass and body mass. Bone mineral measurements did not correlate with fat mass, percentage of fat mass, or cardiorespiratory fitness level. Age was directly correlated with total body mass, body fat, and percentage of fat mass. Body mineral measurements correlated with lean mass but not with fat mass or with cardiorespiratory fitness in this group of young healthy men. Positive association between body fat and age in such young group suggests that more studies with young men are warranted and may help inform strategies to optimize increase in bone mineral measurements.

  6. How Accurate Are the Anthropometry Equations in in Iranian Military Men in Predicting Body Composition?

    PubMed Central

    Shakibaee, Abolfazl; Faghihzadeh, Soghrat; Alishiri, Gholam Hossein; Ebrahimpour, Zeynab; Faradjzadeh, Shahram; Sobhani, Vahid; Asgari, Alireza

    2015-01-01

    Background: The body composition varies according to different life styles (i.e. intake calories and caloric expenditure). Therefore, it is wise to record military personnel’s body composition periodically and encourage those who abide to the regulations. Different methods have been introduced for body composition assessment: invasive and non-invasive. Amongst them, the Jackson and Pollock equation is most popular. Objectives: The recommended anthropometric prediction equations for assessing men’s body composition were compared with dual-energy X-ray absorptiometry (DEXA) gold standard to develop a modified equation to assess body composition and obesity quantitatively among Iranian military men. Patients and Methods: A total of 101 military men aged 23 - 52 years old with a mean age of 35.5 years were recruited and evaluated in the present study (average height, 173.9 cm and weight, 81.5 kg). The body-fat percentages of subjects were assessed both with anthropometric assessment and DEXA scan. The data obtained from these two methods were then compared using multiple regression analysis. Results: The mean and standard deviation of body fat percentage of the DEXA assessment was 21.2 ± 4.3 and body fat percentage obtained from three Jackson and Pollock 3-, 4- and 7-site equations were 21.1 ± 5.8, 22.2 ± 6.0 and 20.9 ± 5.7, respectively. There was a strong correlation between these three equations and DEXA (R² = 0.98). Conclusions: The mean percentage of body fat obtained from the three equations of Jackson and Pollock was very close to that of body fat obtained from DEXA; however, we suggest using a modified Jackson-Pollock 3-site equation for volunteer military men because the 3-site equation analysis method is simpler and faster than other methods. PMID:26715964

  7. Relationship between endogenous 3-methylhistidine excretion and body composition.

    PubMed

    Lukaski, H C; Mendez, J; Buskirk, E R; Cohn, S H

    1981-03-01

    Fourteen healthy men (aged 20-30 yr) consumed two isocaloric, isonitrogenous diets in the sequence of a 4-day meat diet (MD) followed by a 7-day meal-free diet (MFD). Urinary 3-methylhistidine (3MH) excretion during the MD (513 +/- 21 mumol . day-1, mean +/- SE) was significantly higher (P less than 0.01) than day 3 of the MFD (230 +/- 10 mumol . day-1), after which the mean daily 3MH output was constant with a mean coefficient of variation of 4.5%. There was no change in fat-free body mass (FFBM) determined by densitometry at the start (62.3 +/- 1.8 kg) and the end (62.2 +/- 1.9 kg) of the 11-day dietary period. Mean muscle mass (MM) calculated from measurements of total-body potassium and nitrogen was 23.4 +/- 1.3 kg. Endogenous 3MH excretion was related more closely to MM (r = 0.91, P less than 0.001) than to FFBM measured by densitometry (r = 0.81, P less than 0.001). Only a low correlation coefficient (r = 0.33, P less than 0.05) was observed between 3MH and the nonmuscle component of FFBM. Urinary creatinine output also was correlated significantly with 3MH (r = 0.87; P less than 0.001) and MM (r = 0.79; P less than 0.01). It is concluded that because endogenous 3MH is significantly related to MM in man, it can be used as a marker to study in vivo total-body muscle protein degradation provided that the necessary dietary restrictions are observed.

  8. State-of-the-art measurements in human body composition: A moving frontier of clinical importance

    PubMed Central

    Gallagher, D.; Shaheen, I.; Zafar, K.

    2010-01-01

    The measurement of human body composition allows for the estimation of body tissues, organs, and their distributions in living persons without inflicting harm. From a nutritional perspective, the interest in body composition has increased multi-fold with the global increase in the prevalence of obesity and its complications. The latter has driven in part the need for improved measurement methods with greater sensitivity and precision. There is no single gold standard for body-composition measurements in-vivo. All methods incorporate assumptions that do not apply in all individuals and the more accurate models are derived by using a combination of measurements, thereby reducing the importance of each assumption. This review will discuss why the measurement of body composition or human phenotyping is important; discuss new areas where the measurement of body composition (human phenotyping) is recognized as having important application; and will summarize recent advances made in new methodology. Reference will also be made to areas we cannot yet measure due to the lack of appropriate measurement methodologies, most especially measurements methods that provide information on kinetic states (not just static state) and metabolic function. PMID:21234275

  9. Comparison of nutritional intake, body composition, bone mineral density, and isokinetic strength in collegiate female dancers

    PubMed Central

    Lim, Se-Na; Chai, Joo-Hee; Song, Jong Kook; Seo, Myong-Won; Kim, Hyun-Bae

    2015-01-01

    This study compared nutritional intake, body composition, bone mineral density, and isokinetic strength by dance type in collegiate female dancers. The study subjects included Korean dancers (n=12), ballet dancers (n=13), contemporary dancers (n=8), and controls (n=12). Nutritional intake was estimated using the Computer Aided Nutritional Analysis Program. Body composition and bone mineral density were measured using dual-energy X-ray absorptiometry. Isokinetic knee joint strength was measured by Cybex 770-NORM. All statistical analyses were performed by SAS 9.2. Means and standard deviations were calculated using descriptive statistics. One-way analysis of variance was applied to evaluate nutritional intake, body composition, bone mineral density, and isokinetic strength differences. Duncan multiple range test was used for post hoc testing. A level of significance was set at P<0.05. The study results indicated no significant differences in nutritional in-take among dancer types. Despite no significant differences in body composition among dancer types, contemporary and ballet dancers had lower body fat percentages than controls (P<0.05). No significant differences were seen in bone mineral density and bone mineral contents among dancer types. No significant differences were found in isokinetic strength in right or left knee flexion and extension at 60°/sec (P<0.05). There were significant differences in body composition and isokinetic strength between dancer groups and the control group. Further studies of different professional dance type and more scientific methods of dance training are needed. PMID:26730387

  10. Body composition in elderly people: effect of criterion estimates on predictive equations

    SciTech Connect

    Baumgartner, R.N.; Heymsfield, S.B.; Lichtman, S.; Wang, J.; Pierson, R.N. Jr. )

    1991-06-01

    The purposes of this study were to determine whether there are significant differences between two- and four-compartment model estimates of body composition, whether these differences are associated with aqueous and mineral fractions of the fat-free mass (FFM); and whether the differences are retained in equations for predicting body composition from anthropometry and bioelectric resistance. Body composition was estimated in 98 men and women aged 65-94 y by using a four-compartment model based on hydrodensitometry, {sup 3}H{sub 2}O dilution, and dual-photon absorptiometry. These estimates were significantly different from those obtained by using Siri's two-compartment model. The differences were associated significantly (P less than 0.0001) with variation in the aqueous fraction of FFM. Equations for predicting body composition from anthropometry and resistance, when calibrated against two-compartment model estimates, retained these systematic errors. Equations predicting body composition in elderly people should be calibrated against estimates from multicompartment models that consider variability in FFM composition.

  11. Functional Body Composition and Related Aspects in Research on Obesity and Cachexia

    PubMed Central

    Müller, M.J.; Baracos, V.; Bosy-Westphal, A.; Dulloo, A.; Eckel, J.; Fearon, K.C.H.; Hall, K.D.; Pietrobelli, A.; Sørensen, T.I.A.; Speakman, J.; Trayhurn, P.; Visser, M.; Heymsfield, S.B.

    2014-01-01

    The 12th Stock Conference addressed body composition and related functions in two extreme situations, obesity and cancer cachexia. The concept of “functional body composition” integrates body components into regulatory systems relating the mass of organs and tissues to corresponding in vivo functions and metabolic processes. This concept adds to an understanding of organ/tissue mass and function in the context of metabolic adaptations to weight change and disease. During weight gain and loss there are associated changes in individual body components while the relationships between organ and tissue mass are fixed. Thus, an understanding of weight regulation involves an examination of organ-tissue regulation rather than of individual organ mass. The between organ/tissue mass relationships are associated with and explained by cross-talk between organs and tissues mediated by cytokines, hormones, and metabolites that are coupled with changes in body weight, composition, and function as observed in obesity and cancer cachexia. In addition to established roles in intermediary metabolism, cell function and inflammation, organ-tissue cross-talk mediators are determinants of body composition and its’ change with weight gain and loss. The 12th Stock Conference supported Michael Stocks’ concept of gaining new insights by integrating research ideas from obesity and cancer cachexia. The conference presentations provide an in-depth understanding of body composition and metabolism. PMID:24835453

  12. Body Composition, Sarcopenia, and Suicidal Ideation in Elderly Koreans: Hallym Aging Study

    PubMed Central

    2016-01-01

    This study was conducted to assess the relationship between body composition and suicidal ideation among the Korean elderly population (n = 302; ≥ 65 years) who participated in the Hallym Aging Study in 2010. Body composition was measured using dual-energy X-ray absorptiometry, and obesity was measured by the indices of body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), and body fat percentage. Sarcopenia was defined as presence of both low muscle mass and low muscle function. Suicidal ideation was assessed using the Beck Scale for Suicide Ideation. We found no differences in body composition measures between subjects with suicidal ideation and those without. In the logistic regression analyses, there were no significant relationships for suicidal ideation according to body composition measures, including BMI, WC, WHR, WHtR, and body fat percentage in both sexes. After adjusting for age, smoking status, alcohol drinking, regular exercise, medical comorbidities, monthly income, education level, and presence of depressive symptoms, the odds ratio (OR) of suicidal ideation was higher in elderly men with sarcopenia compared to those without, whereas no significant relationships were observed in elderly women (OR 8.28, 95% confidence interval [CI] 1.20–61.34 in men; OR 0.79, 95% CI 0.07–8.43 in women). Sarcopenia is closely associated with an increased risk of suicidal ideation in elderly men. PMID:27051246

  13. Silicon carbide ceramic production

    NASA Technical Reports Server (NTRS)

    Suzuki, K.; Shinohara, N.

    1984-01-01

    A method to produce sintered silicon carbide ceramics in which powdery carbonaceous components with a dispersant are mixed with silicon carbide powder, shaped as required with or without drying, and fired in nonoxidation atmosphere is described. Carbon black is used as the carbonaceous component.

  14. [Energy balance, body composition and the female athlete triad syndrome].

    PubMed

    Weinstein, Yitzhak; Weinstein, Ayelet

    2012-02-01

    With the rising participation of women in sports events, the prevalence of eating disorders and the female athlete triad (FTS), a syndrome of disordered eating, amenorrhea, and osteoporosis, have also increased in recent years. FTS is often seen in sports that emphasize thinness (e.g. gymnastics, figure skating and dancing) and also in endurance events. Elements of the FTS are pathophysiologically linked, leading to several disease risks and even to mortality. In spite of the considerable knowledge about sports nutrition, there is no consensus as to the correct nutrition regime for the female athlete. There is consensus that minimizing fluctuations in 'target-body-weight' is an indication of a long-term energy balance. Female athletes (e.g. in endurance events and gymnastics) are less likely to achieve the recommended carbohydrates (CHO) and fat consumption due to chronic or episodic constraints of total energy intake while struggling to achieve or maintain low levels of body fat. It is recommended that dietary CHO and fat content be increased to preserve fat-free mass thus enhancing health and performance. Energy balance should also be maintained during recesses. Furthermore, within-day episodes of energy deficits/surplus (measured by the frequency and/or magnitude of the episodes) should be monitored and treated closest to the time of the incidents. PMID:22741211

  15. Bioimpedance as a tool for evaluating the body composition of suruvi (Steindachneridion scriptum).

    PubMed

    Zaniboni-Filho, E; Hermes-Silva, S; Weingartner, M; Jimenez, J E; Borba, M R; Fracalossi, D M

    2015-11-01

    Bioelectrical impedance analysis (BIA) is regarded as an important tool for evaluating the body composition of different animals in a rapid, non-destructive, and low-cost manner. A South American fish species, Steindachneridion scriptum, known as suruvi, was selected for study in this investigation. A protocol to produce fish with different body composition was used to allow BIA to adequately predict the body composition of suruvi. The fish were fed twice each day with two different diets; a low lipid diet (8.90%), and a high lipid diet (18.68%). These dietary differences allowed suruvi specimens with different body compositions to be produced. The BIA readings were determined using a Quantum X Bioelectrical Body Composition Analyzer. Two readings (dorsal and ventral) were obtained for each fish. After BIA readings were obtained, the proximate composition of the fish bodies for each individual was determined. All of the study data were used to establish correlation equations between proximate analyses and BIA values. Strong correlations were found for S. scriptum. The highest correlations were obtained for the following pairs of quantities, using BIA data from dorsal readings: moisture and resistance in series (R2 = 0.87); protein and resistance in series (R2 = 0.87); and ash and reactance in parallel (R2 = 0.82). We conclude that BIA is an effective method in determining the body composition of S. scriptum without sacrificing the fish. However, to expand the use of this new technology it is important to define strict BIA protocols to guarantee accurate estimates. PMID:26602350

  16. Bioimpedance as a tool for evaluating the body composition of suruvi (Steindachneridion scriptum).

    PubMed

    Zaniboni-Filho, E; Hermes-Silva, S; Weingartner, M; Jimenez, J E; Borba, M R; Fracalossi, D M

    2015-11-01

    Bioelectrical impedance analysis (BIA) is regarded as an important tool for evaluating the body composition of different animals in a rapid, non-destructive, and low-cost manner. A South American fish species, Steindachneridion scriptum, known as suruvi, was selected for study in this investigation. A protocol to produce fish with different body composition was used to allow BIA to adequately predict the body composition of suruvi. The fish were fed twice each day with two different diets; a low lipid diet (8.90%), and a high lipid diet (18.68%). These dietary differences allowed suruvi specimens with different body compositions to be produced. The BIA readings were determined using a Quantum X Bioelectrical Body Composition Analyzer. Two readings (dorsal and ventral) were obtained for each fish. After BIA readings were obtained, the proximate composition of the fish bodies for each individual was determined. All of the study data were used to establish correlation equations between proximate analyses and BIA values. Strong correlations were found for S. scriptum. The highest correlations were obtained for the following pairs of quantities, using BIA data from dorsal readings: moisture and resistance in series (R2 = 0.87); protein and resistance in series (R2 = 0.87); and ash and reactance in parallel (R2 = 0.82). We conclude that BIA is an effective method in determining the body composition of S. scriptum without sacrificing the fish. However, to expand the use of this new technology it is important to define strict BIA protocols to guarantee accurate estimates.

  17. Fitness level and body composition indices: cross-sectional study among Malaysian adolescent

    PubMed Central

    2014-01-01

    Background The importance of fitness level on the well-being of children and adolescent has long been recognised. The aim of this study was to investigate the fitness level of school-going Malaysian adolescent, and its association with body composition indices. Methods 1071 healthy secondary school students participated in the fitness assessment for the Malaysian Health and Adolescents Longitudinal Research Team (MyHEART) study. Body composition indices such as body mass index for age, waist circumference and waist height ratio were measured. Fitness level was assessed with Modified Harvard Step Test. Physical Fitness Score was calculated using total time of step test exercise and resting heart rates. Fitness levels were divided into 3 categories - unacceptable, marginally acceptable, and acceptable. Partial correlation analysis was used to determine the association between fitness score and body composition, by controlling age, gender, locality, ethnicity, smoking status and sexual maturation. Multiple regression analysis was conducted to determine which body composition was the strongest predictor for fitness. Results 43.3% of the participants were categorised into the unacceptable fitness group, 47.1% were considered marginally acceptable, and 9.6% were acceptable. There was a significant moderate inverse association (p < 0.001) between body composition with fitness score (r = -0.360, -0.413 and -0.403 for body mass index for age, waist circumference and waist height ratio, respectively). Waist circumference was the strongest and significant predictor for fitness (ß = -0.318, p = 0.002). Conclusion Only 9.6% of the students were fit. There was also an inverse association between body composition and fitness score among apparently healthy adolescents, with waist circumference indicated as the strongest predictor. The low fitness level among the Malaysian adolescent should necessitate the value of healthy lifestyle starting at a young age. PMID:25436933

  18. Shuttle-food consumption, body composition and body weight in women

    NASA Technical Reports Server (NTRS)

    Lane, Helen W.; Frye, Sherrie; Kloeris, Vickie; Rice, Barbara; Siconolfi, Steven F.; Spector, Elisabeth; Gretebeck, Randall J.

    1992-01-01

    An experiment is conducted to determine whether the NASA Space Shuttle food system can provide the food and fluid required to mitigate weight loss and physical decomposition in 12 female subjects for 28 days. Subjects receive only foods from the Space Shuttle system for four weeks within an 11-wk monitoring period. Dual-energy X-ray absorptiometry is employed throughout the trial period to study lean body mass, percent body fat, and energy-intake levels with attention given to differences the experimental diet and the subjects' typical diet. Percent body fat is found to change significantly with losses of less than 0.05 percent, whereas energy intake based on autonomous diet choices by the participants does not vary significantly. Lean body mass remains unchanged throughout the study in which the subjects receive a relatively low-fat and low-protein menu. The 100 items on the space shuttle list of approved food items are shown to provide a palatable dietary framework for maintaining the health of female astronauts.

  19. [EFFECTS OF WHOLE-BODY VIBRATION TRAINING ON BODY COMPOSITION AND PHYSICAL FITNESS IN RECREATIONALLY ACTIVE YOUNG ADULTS].

    PubMed

    Martínez-Pardo, Esmeraldo; Martínez-Ruiz, Enrique; Alcaraz, Pedro E; Rubio-Arias, Jacobo A

    2015-11-01

    In the last decade, it has been suggested that whole- body vibration training (WBV) may increase neuromuscular performance and consequently affect the muscular improvement as either acute response to vibration or chronic adaptation training. Vibrating platforms generate frequencies from 5-45 Hz and vertical oscillations of 1-11 mm peak to peak, affecting more or less intensity acceleration changing by combining frequency and amplitude. Vibration training, in a session as various offers different results in regard to changes in body composition and in increasing the vertical jump, sprint, and the different manifestations of force development. These promising results await further research to establish parameters (duration, frequency and amplitude) with vibration stimulation in young active subjects. This literature review provides an update on the scientific evidence on the body vibrations in order to answer the question whether WBV, meaning the exercise by increasing the gravitational load collection, is a treatment option if the aim is to improve neuromuscular function, flexibility, balance, agility, coordination and body composition.

  20. [EFFECTS OF WHOLE-BODY VIBRATION TRAINING ON BODY COMPOSITION AND PHYSICAL FITNESS IN RECREATIONALLY ACTIVE YOUNG ADULTS].

    PubMed

    Martínez-Pardo, Esmeraldo; Martínez-Ruiz, Enrique; Alcaraz, Pedro E; Rubio-Arias, Jacobo A

    2015-01-01

    In the last decade, it has been suggested that whole- body vibration training (WBV) may increase neuromuscular performance and consequently affect the muscular improvement as either acute response to vibration or chronic adaptation training. Vibrating platforms generate frequencies from 5-45 Hz and vertical oscillations of 1-11 mm peak to peak, affecting more or less intensity acceleration changing by combining frequency and amplitude. Vibration training, in a session as various offers different results in regard to changes in body composition and in increasing the vertical jump, sprint, and the different manifestations of force development. These promising results await further research to establish parameters (duration, frequency and amplitude) with vibration stimulation in young active subjects. This literature review provides an update on the scientific evidence on the body vibrations in order to answer the question whether WBV, meaning the exercise by increasing the gravitational load collection, is a treatment option if the aim is to improve neuromuscular function, flexibility, balance, agility, coordination and body composition. PMID:26545648

  1. Use of bioelectrical impedance analysis to determine body composition changes in HIV-associated wasting.

    PubMed

    Klauke, Stephan; Fischer, Harald; Rieger, Armin; Frühauf, Lukas; Staszewski, Schlomo; Althoff, Peter-Henning; Helm, Eilke Brigitte

    2005-04-01

    AIDS wasting syndrome results in loss of lean body mass and body cell mass. This 12-week, open-label study used bioelectrical impedance analysis to measure body composition changes in 24 patients with AIDS wasting syndrome receiving recombinant human growth hormone (r-hGH). The primary endpoint was percentage monthly change in body weight before/after r-hGH. Secondary endpoints included change from baseline in body composition (bioelectrical impedance analysis), isometric strength and CD4+ count. Twenty patients completed the study: r-hGH resulted in mean weight gains (+2.7%, P = 0.146), and significant increases in mean body cell mass (+8.0%, P = 0.0211), lean body mass (+4.8%, P = 0.0373) and water (+5.5%, P < 0.023). Body fat decreased throughout, but not significantly. r-hGH was generally well tolerated; the most frequent adverse events were fever (7.3%) and diarrhoea (6.3%). Thus, bioelectrical impedance analysis can detect improved body cell mass independent of changes in body weight resulting from r-hGH treatment in patients with AIDS wasting syndrome.

  2. Body composition in patients with rheumatoid arthritis is not different than healthy subjects

    PubMed Central

    Akar, Servet; Sarı, İsmail; Çömlekci, Abdurrahman; Birlik, Merih; Önen, Fatoş; Göktay, Yiğit; Özaksoy, Dinc; Akkoç, Nurullah

    2014-01-01

    Objective Rheumatoid arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD). Increased body fat, particularly its central distribution, is a well-known risk factor for CVD. A change in body composition in RA has been described previously. However, in most of these studies, age- and sex- but not body mass index (BMI)-matched controls were used. The aim of this study was to evaluate body composition in RA patients and compare it with age-, sex-, and BMI-matched controls. Material and Methods Sixty-five RA patients (55 females and 10 males; mean age 54.9 ± 10.8) and 31 healthy controls (25 females, 6 males; 53.8±8.6) were included in this study. Mean disease duration was 9.2±9.6 years. Body composition was assessed by anthropometric methods (skinfold thicknesses, body circumferences), bioimpedance analysis, and dual-energy X-ray absorptiometry (DXA). Visceral adipose tissue (VAT) was assessed with computed tomography. Results There were no significant differences for total body fatness, regional fat distribution, and total body water and fat-free mass between RA patients and control subjects. Bone mineral content (BMC), assessed by DXA, was significantly lower in RA patients (p=0.004). Clinical disease activity indices and steroid treatment do not affect soft tissue body composition or BMC. Conclusion At least some RA patients do not have soft tissue composition alterations and may have similar health risks in comparison with subjects with similar age, sex, and total adiposity.

  3. The effect of chromium picolinate on muscular strength and body composition in women athletes.

    PubMed

    Livolsi, J M; Adams, G M; Laguna, P L

    2001-05-01

    Fifteen women softball athletes were randomly divided into 2 groups, the chromium treatment group (n = 8) and the placebo control group (n = 7) to examine the effect of chromium, in the form of chromium picolinate (CrPic) supplementation, on muscular strength, body composition (body weight, percent body fat, and lean body mass), and urinary excretion. The CrPic supplementation consisted of a 500 ug dosage taken once per day. All participants trained 3 times per week with 2-3 sets of 8-12 repetitions at 80% of 1 repetition maximum (1RM) using variable resistance machines and free weights. No significant (p < 0.05) differences in muscular strength or body composition were found after 6 weeks of resistance training. In addition, chromium excretion (microg per 24 every hours) was examined and increased significantly with the treatment group after the 6-week period.

  4. Childhood cognitive ability and body composition in adulthood

    PubMed Central

    Kumpulainen, S M; Heinonen, K; Salonen, M K; Andersson, S; Wolke, D; Kajantie, E; Eriksson, J G; Raikkonen, K

    2016-01-01

    Background: Childhood cognitive ability has been identified as a novel risk factor for adulthood overweight and obesity as assessed by adult body mass index (BMI). BMI does not, however, distinguish fat-free and metabolically harmful fat tissue. Hence, we examined the associations between childhood cognitive abilities and body fat percentage (BF%) in young adulthood. Methods: Participants of the Arvo Ylppö Longitudinal Study (n=816) underwent tests of general reasoning, visuomotor integration, verbal competence and language comprehension (M=100; s.d.=15) at the age of 56 months. At the age of 25 years, they underwent a clinical examination, including measurements of BF% by the InBody 3.0 eight-polar tactile electrode system, weight and height from which BMI (kg m−2) was calculated and waist circumference (cm). Results: After adjustments for sex, age and BMI-for-age s.d. score at 56 months, lower general reasoning and visuomotor integration in childhood predicted higher BMI (kg m−2) increase per s.d. unit decrease in cognitive ability (−0.32, 95% confidence interval −0.60,−0.05; −0.45, −0.75,−0.14, respectively) and waist circumference (cm) increase per s.d. unit decrease in cognitive ability (−0.84, −1.56,−0.11; −1.07,−1.88,−0.26, respectively) in adulthood. In addition, lower visuomotor integration predicted higher BF% per s.d. unit decrease in cognitive ability (−0.62,−1.14,−0.09). Associations between general reasoning and BMI/waist were attenuated when adjusted for smoking, alcohol consumption, intake of fruits and vegetables and physical activity in adulthood, and all associations, except for visuomotor integration and BMI, were attenuated when adjusted for parental and/or own attained education and/or birth weight. Conclusions: Of the measured childhood cognitive abilities, only lower visuomotor integration was associated with BF% in adulthood. This challenges the view that cognitive ability, at least when measured in

  5. The pristine nature of comets. [primeval composition of solar bodies

    NASA Technical Reports Server (NTRS)

    Delsemme, A. H.

    1977-01-01

    Abundance considerations suggest that comets are likely to be the most pristine minor bodies in the solar system. In proportion to solar abundances, the present scanty data suggest that cometary oxygen is not depleted, whereas carbon is by a factor of 4 and hydrogen, by a factor of 2000. This implies that comets are less depleted in H, C, N, O than CI chondrites, namely 10:1 in hydrogen, 4:1 in carbon and 3:1 in oxygen. These results have been obtained by using dust-to-gas ratios in comets to measure the relative abundance of silicon and metals to volatile material, and the spectra of atomic lines, mainly from the vacuum ultraviolet, to determine the H/O and C/O ratios of the mixture of volatile molecules.

  6. Lipid metabolism and body composition in Gclm(-/-) mice

    SciTech Connect

    Kendig, Eric L.; Chen, Ying; Krishan, Mansi; Johansson, Elisabet; Schneider, Scott N.; Genter, Mary Beth; Nebert, Daniel W.; Shertzer, Howard G.

    2011-12-15

    In humans and experimental animals, high fat diets (HFD) are associated with risk factors for metabolic diseases, such as excessive weight gain and adiposity, insulin resistance and fatty liver. Mice lacking the glutamate-cysteine ligase modifier subunit gene (Gclm(-/-)) and deficient in glutathione (GSH), are resistant to HFD-mediated weight gain. Herein, we evaluated Gclm-associated regulation of energy metabolism, oxidative stress, and glucose and lipid homeostasis. C57BL/6J Gclm(-/-) mice and littermate wild-type (WT) controls received a normal diet or an HFD for 11 weeks. HFD-fed Gclm(-/-) mice did not display a decreased respiratory quotient, suggesting that they are unable to process lipid for metabolism. Although dietary energy consumption and intestinal lipid absorption were unchanged in Gclm(-/-) mice, feeding these mice an HFD did not produce excess body weight nor fat storage. Gclm(-/-) mice displayed higher basal metabolic rates resulting from higher activities of liver mitochondrial NADH-CoQ oxidoreductase, thus elevating respiration. Although Gclm(-/-) mice exhibited strong systemic and hepatic oxidative stress responses, HFD did not promote glucose intolerance or insulin resistance. Furthermore, HFD-fed Gclm(-/-) mice did not develop fatty liver, likely resulting from very low expression levels of genes encoding lipid metabolizing enzymes. We conclude that Gclm is involved in the regulation of basal metabolic rate and the metabolism of dietary lipid. Although Gclm(-/-) mice display a strong oxidative stress response, they are protected from HFD-induced excessive weight gain and adipose deposition, insulin resistance and steatosis. -- Highlights: Black-Right-Pointing-Pointer A high fat diet does not produce body weight and fat gain in Gclm(-/-) mice. Black-Right-Pointing-Pointer A high fat diet does not induce steatosis or insulin resistance in Gclm(-/-) mice. Black-Right-Pointing-Pointer Gclm(-/-) mice have high basal metabolism and mitochondrial

  7. Anthropometry and Body Composition of Adolescents in Cracow, Poland

    PubMed Central

    Hołda, Mateusz K.; Piątek, Katarzyna; Wszołek, Karolina; Tyszka, Anna; Kmiotek, Elizabeth; Pliczko, Mateusz; Śliwińska, Aleksandra; Krauss, Klaudia; Miszczyk, Marcin; Walocha, Jerzy

    2015-01-01

    Background and Objective The aim of the present study was to determine the level of adiposity and obesity in Polish adolescents and compare the results with earlier studies conducted in this population as well as those carried out in other populations. Methods The study group consisted of 456 boys and 514 girls aged 14-18 years living in Cracow chosen from randomly selected secondary schools. Weight, height, waist, and hip circumference (WC, HC) as well as triceps, biceps, subscapular, and suprailiac skinfold thickness (SFT) were measured. Body mass index (BMI), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), subscapular/triceps skinfold ratio (STR), and percentage body fat were computed. The prevalence of overweight and obesity based on Polish children growth reference were calculated and age-dependent and gender-specific smoothed percentile curves for BMI and ROC curves were generated. Results Weight, height, WC, HC (up 16yr), WHtR (up 15yr), and WHR were considerably higher in males than females. Weight, height, and HC increased with age; WHtR remained the same. The prevalence of overweight and obesity were 10.2% (boys 10.3%; girls 10.1%) and 4.2% (boys 5.3%; girls 3.3%). ROC analysis revealed that WHtR was the best tool for detection of obesity (AUC of 0.982±0.007) in males, whereas the sum of four SFTs (AUC: 0.968±0.011) and WHtR (AUC: 0.963±0.012) were the best predictors of obesity in females. Conclusions The level of adiposity in Cracow adolescents increased during the last decade. However, it is still lower than in other well-developed societies struggling with obesity epidemics. PMID:25815816

  8. Boron-carbide-aluminum and boron-carbide-reactive metal cermets. [B/sub 4/C-Al

    DOEpatents

    Halverson, D.C.; Pyzik, A.J.; Aksay, I.A.

    1985-05-06

    Hard, tough, lighweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidated step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modules of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi..sqrt..in. These composites and methods can be used to form a variety of structural elements.

  9. Glucose Homeostasis Variables in Pregnancy versus Maternal and Infant Body Composition

    PubMed Central

    Henriksson, Pontus; Löf, Marie; Forsum, Elisabet

    2015-01-01

    Intrauterine factors influence infant size and body composition but the mechanisms involved are to a large extent unknown. We studied relationships between the body composition of pregnant women and variables related to their glucose homeostasis, i.e., glucose, HOMA-IR (homeostasis model assessment-insulin resistance), hemoglobin A1c and IGFBP-1 (insulin-like growth factor binding protein-1), and related these variables to the body composition of their infants. Body composition of 209 women in gestational week 32 and of their healthy, singleton and full-term one-week-old infants was measured using air displacement plethysmography. Glucose homeostasis variables were assessed in gestational week 32. HOMA-IR was positively related to fat mass index and fat mass (r2 = 0.32, p < 0.001) of the women. Maternal glucose and HOMA-IR values were positively (p ≤ 0.006) associated, while IGFBP-1was negatively (p = 0.001) associated, with infant fat mass. HOMA-IR was positively associated with fat mass of daughters (p < 0.001), but not of sons (p = 0.65) (Sex-interaction: p = 0.042). In conclusion, glucose homeostasis variables of pregnant women are related to their own body composition and to that of their infants. The results suggest that a previously identified relationship between fat mass of mothers and daughters is mediated by maternal insulin resistance. PMID:26184296

  10. Imaging methods for analyzing body composition in human obesity and cardiometabolic disease.

    PubMed

    Seabolt, Lynn A; Welch, E Brian; Silver, Heidi J

    2015-09-01

    Advances in the technological qualities of imaging modalities for assessing human body composition have been stimulated by accumulating evidence that individual components of body composition have significant influences on chronic disease onset, disease progression, treatment response, and health outcomes. Importantly, imaging modalities have provided a systematic method for differentiating phenotypes of body composition that diverge from what is considered normal, that is, having low bone mass (osteopenia/osteoporosis), low muscle mass (sarcopenia), high fat mass (obesity), or high fat with low muscle mass (sarcopenic obesity). Moreover, advances over the past three decades in the sensitivity and quality of imaging not just to discern the amount and distribution of adipose and lean tissue but also to differentiate layers or depots within tissues and cells is enhancing our understanding of distinct mechanistic, metabolic, and functional roles of body composition within human phenotypes. In this review, we focus on advances in imaging technologies that show great promise for future investigation of human body composition and how they are being used to address the pandemic of obesity, metabolic syndrome, and diabetes.

  11. Imaging methods for analyzing body composition in human obesity and cardiometabolic disease.

    PubMed

    Seabolt, Lynn A; Welch, E Brian; Silver, Heidi J

    2015-09-01

    Advances in the technological qualities of imaging modalities for assessing human body composition have been stimulated by accumulating evidence that individual components of body composition have significant influences on chronic disease onset, disease progression, treatment response, and health outcomes. Importantly, imaging modalities have provided a systematic method for differentiating phenotypes of body composition that diverge from what is considered normal, that is, having low bone mass (osteopenia/osteoporosis), low muscle mass (sarcopenia), high fat mass (obesity), or high fat with low muscle mass (sarcopenic obesity). Moreover, advances over the past three decades in the sensitivity and quality of imaging not just to discern the amount and distribution of adipose and lean tissue but also to differentiate layers or depots within tissues and cells is enhancing our understanding of distinct mechanistic, metabolic, and functional roles of body composition within human phenotypes. In this review, we focus on advances in imaging technologies that show great promise for future investigation of human body composition and how they are being used to address the pandemic of obesity, metabolic syndrome, and diabetes. PMID:26250623

  12. Indicators of Walking Speed in Rheumatoid Arthritis: Relative Influence of Articular, Psychosocial, and Body Composition Characteristics

    PubMed Central

    Lusa, Amanda L; Amigues, Isabelle; Kramer, Henry R; Dam, Thuy-Tien; Giles, Jon T

    2014-01-01

    Objective To explore the contributions from and interactions between articular swelling and damage, psychosocial factors, and body composition characteristics on walking speed in rheumatoid arthritis (RA). Methods RA patients underwent the timed 400 meter long-corridor walk. Demographics, self-reported levels of depressive symptoms and fatigue, RA characteristics, and body composition [using whole-body dual-energy X-ray absorptiometry (DXA), and abdominal and thigh computed tomography (CT)] were assessed and their associations with walking speed explored. Results A total of 132 RA patients had data for the 400 meter walk, among whom 107 (81%) completed the full 400 meters. Significant multivariable indicators of slower walking speed were older age, higher depression scores, higher reported pain and fatigue, higher swollen and replaced joint counts, higher cumulative prednisone exposure, non-treatment with disease-modifying anti-rheumatic drugs (DMARDs), and worse body composition. These features accounted for 60% of the modeled variability in walking speed. Among specific articular features, slower walking speed was primarily correlated with large/medium lower-extremity joint involvement. However, these articular features accounted for only 21% of the explainable variability in walking speed. Having any relevant articular characteristics was associated with a 20% lower walking speed among those with worse body composition (p<0.001) compared with only a 6% lower speed among those with better body composition (p-value for interaction=0.010). Conclusions Psychosocial factors and body composition are potentially reversible contributors to walking speed in RA. Relative to articular disease activity and damage, non-articular indicators were collectively more potent indicators of an individual's mobility limitations. PMID:25155859

  13. Postnatal Anthropometric and Body Composition Profiles in Infants with Intrauterine Growth Restriction Identified by Prenatal Doppler

    PubMed Central

    Mazarico, E.; Martinez-Cumplido, R.; Díaz, M.; Sebastiani, G.; Ibáñez, L.; Gómez-Roig, M. D.

    2016-01-01

    Introduction Infant anthropometry and body composition have been previously assessed to gauge the impact of intrauterine growth restriction (IUGR) at birth, but the interplay between prenatal Doppler measurements and postnatal development has not been studied in this setting. The present investigation was performed to assess the significance of prenatal Doppler findings relative to postnatal anthropometrics and body composition in IUGR newborns over the first 12 months of life. Patients and Methods Consecutive cases of singleton pregnancies with suspected IUGR were prospectively enrolled over 12 months. Fetal biometry and prenatal Doppler ultrasound examinations were performed. Body composition was assessed by absorptiometry at ages 10 days, and at 4 and12 months. Results A total of 48 pregnancies qualifying as IUGR were studied. Doppler parameters were normal in 26 pregnancies. The remaining 22 deviated from normal, marked by an Umbilical Artery Pulsatility Index (UA-PI) >95th centil or Cerebro-placental ratio (CPR) <5th centile. No significant differences emerged when comparing anthropometry and body composition at each time point, in relation to Doppler findings. Specifically, those IUGR newborns with and without abnormal Doppler findings had similar weight, length, body mass index, lean and fat mass, and bone mineral content throughout the first 12 months of life. In a separate analysis, when comparing IUGR newborns by Doppler (abnormal UA-PI vs. abnormal CPR), anthropometry and body composition did not differ significantly. Conclusions Infants with IUGR maintain a pattern of body composition during the first year of life that is independent of prenatal Doppler findings. Future studies with larger sample sizes and correlating with hormonal status are warranted to further extend the phenotypic characterization of the various conditions now classified under the common label of IUGR. PMID:26938993

  14. Body Composition and Cardiovascular Risk Markers after Remission of Cushing's Disease: A Prospective Study Using Whole-Body MRI

    PubMed Central

    Shen, Wei; Strohmayer, Erika; Post, Kalmon D.; Freda, Pamela U.

    2012-01-01

    Context: Cushing's Disease (CD) alters fat distribution, muscle mass, adipokine profile, and cardiovascular risk factors. It is not known whether remission entirely reverses these changes. Objectives: Our objective was to determine whether the adverse body composition and cardiovascular risk profile in CD change after remission. Design, Setting, and Patients: Fourteen CD patients were studied prospectively: before surgery (active disease) and again postoperatively 6 months after discontinuing oral glucocorticoids (remission). Whole-body magnetic resonance imaging was used to examine lean and fat tissue distributions. Outcome Measures: Body composition (skeletal muscle and fat in the visceral, bone marrow, sc, and inter-muscular compartments) and cardiovascular risk factors (serum insulin, glucose, leptin, high-molecular-weight adiponectin, C-reactive protein, and lipid profile) were measured in active CD and remission (mean 20 months after surgery). Results: Remission decreased visceral, pelvic bone marrow, sc (including trunk and limb sc), and total fat; waist circumference; and weight (P < 0.05). Remission altered fat distribution, resulting in decreased visceral/total fat (P = 0.04) and visceral fat/skeletal muscle ratios (P = 0.006). Remission decreased the absolute muscle mass (P = 0.015). Cardiovascular risk factors changed: insulin resistance, leptin, and total cholesterol decreased (P < 0.05), but adiponectin, C-reactive protein, and other lipid measures did not change. Conclusions: CD remission reduced nearly all fat depots and reverted fat to a distribution more consistent with favorable cardiovascular risk but decreased skeletal muscle. Remission improved some but not all cardiovascular risk markers. Remission from CD dramatically improves body composition abnormalities but may still be associated with persistent cardiovascular risk. PMID:22419708

  15. Altered body composition in type 2 diabetes mellitus

    PubMed Central

    Heshka, Stanley; Ruggiero, Andrea; Bray, George A.; Foreyt, John; Kahn, Stephen E.; Lewis, Cora E.; Saad, Mohammed; Schwartz, Ann V.

    2010-01-01

    Objective To identify differences in amount and distribution of fat and lean soft tissue in subjects with and without type 2 diabetes and to determine whether any differences are affected by race/ethnicity or sex. Design Overweight and obese (body mass index, BMI≥25 kg/m2) Black, White and Hispanic men (490) and women (825) with type 2 diabetes ([mean±SD] age 58.5±6.6; BMI 35.3±5.3) who had a baseline dual energy x-ray absorptiometry whole body scan at the time of enrollment in the Look Ahead clinical trial, and 242 healthy controls, 91 males and 151 females (age 55.3±8.6 y, BMI 30.7±4.2 kg/m2) who were participating in unrelated research and were scanned on the same densitometers. Results Adjusted for covariates, total fat mass was smaller in persons with type 2 diabetes than in controls (−1.4±0.3[SE]; 34.5 vs 35.8 kg, p<0.001) while trunk fat was larger (1.3±0.2[SE]; 19.9 vs 18.6 kg, p<0.001) and leg fat was smaller (−1.5±0.2[SE]; 10.7 vs 12.3 kg, p<0.001). The arms of subjects with type 2 diabetes did not have significantly less fat compared to controls. Adjusted trunk lean mass was larger in type 2 diabetes by 0.6 kg (28.4 vs 27.8 kg, p<0.001) while leg lean was smaller by 0.5 kg (18.1 vs 18.6 kg, p<0.001). Conclusions Type 2 diabetes is associated with less total fat, leg fat and leg lean mass and more truncal fat and lean mass than controls. The physiological processes producing these deviations in tissue distribution and their metabolic significance warrant further investigation. (ClinicalTrials.gov number, NCT00017953) PMID:18227843

  16. Controlling parental feeding practices and child body composition in ethnically and economically diverse preschool children.

    PubMed

    Wehrly, Sarah E; Bonilla, Chantal; Perez, Marisol; Liew, Jeffrey

    2014-02-01

    Controlling parental feeding practices may be associated with childhood overweight, because coercive or intrusive feeding practices may negatively impact children's development of self-regulation of eating. This study examined pressuring or forcing a child (healthy or unhealthy foods) and restricting child from unhealthy or snack foods as two types of controlling feeding practices that explain unique variances in measures of child body composition (BMI, percent body fat, and parental perception of child weight). In an ethnically and economically diverse sample of 243 children aged 4-6years old and their biological parents (89% biological mothers, 8% biological fathers, and 3% step or grand-parent), descriptive statistics indicate ethnic and family income differences in measures of feeding practices and child body composition. Additionally, the two "objective" indices of body composition (BMI and percent body fat) were related to low pressure to eat, whereas the "subjective" index (perceived child weight) was related to restriction. Regression analyses accounting for ethnic and family income influences indicate that pressure to eat and restriction both explained unique variances in the two "objective" indices of body composition, whereas only restriction explained variance in perceived child weight. Findings have implications for helping parents learn about feeding practices that promote children's self-regulation of eating that simultaneously serves as an obesity prevention strategy. PMID:24269508

  17. Administration of Saccharin to Neonatal Mice Influences Body Composition of Adult Males and Reduces Body Weight of Females

    PubMed Central

    Parlee, Sebastian D.; Simon, Becky R.; Scheller, Erica L.; Alejandro, Emilyn U.; Learman, Brian S.; Krishnan, Venkatesh; Bernal-Mizrachi, Ernesto

    2014-01-01

    Nutritional or pharmacological perturbations during perinatal growth can cause persistent effects on the function of white adipose tissue, altering susceptibility to obesity later in life. Previous studies have established that saccharin, a nonnutritive sweetener, inhibits lipolysis in mature adipocytes and stimulates adipogenesis. Thus, the current study tested whether neonatal exposure to saccharin via maternal lactation increased susceptibility of mice to diet-induced obesity. Saccharin decreased body weight of female mice beginning postnatal week 3. Decreased liver weights on week 14 corroborated this diminished body weight. Initially, saccharin also reduced male mouse body weight. By week 5, weights transiently rebounded above controls, and by week 14, male body weights did not differ. Body composition analysis revealed that saccharin increased lean and decreased fat mass of male mice, the latter due to decreased adipocyte size and epididymal, perirenal, and sc adipose weights. A mild improvement in glucose tolerance without a change in insulin sensitivity or secretion aligned with this leaner phenotype. Interestingly, microcomputed tomography analysis indicated that saccharin also increased cortical and trabecular bone mass of male mice and modified cortical bone alone in female mice. A modest increase in circulating testosterone may contribute to the leaner phenotype in male mice. Accordingly, the current study established a developmental period in which saccharin at high concentrations reduces adiposity and increases lean and bone mass in male mice while decreasing generalized growth in female mice. PMID:24456165

  18. Administration of saccharin to neonatal mice influences body composition of adult males and reduces body weight of females.

    PubMed

    Parlee, Sebastian D; Simon, Becky R; Scheller, Erica L; Alejandro, Emilyn U; Learman, Brian S; Krishnan, Venkatesh; Bernal-Mizrachi, Ernesto; MacDougald, Ormond A

    2014-04-01

    Nutritional or pharmacological perturbations during perinatal growth can cause persistent effects on the function of white adipose tissue, altering susceptibility to obesity later in life. Previous studies have established that saccharin, a nonnutritive sweetener, inhibits lipolysis in mature adipocytes and stimulates adipogenesis. Thus, the current study tested whether neonatal exposure to saccharin via maternal lactation increased susceptibility of mice to diet-induced obesity. Saccharin decreased body weight of female mice beginning postnatal week 3. Decreased liver weights on week 14 corroborated this diminished body weight. Initially, saccharin also reduced male mouse body weight. By week 5, weights transiently rebounded above controls, and by week 14, male body weights did not differ. Body composition analysis revealed that saccharin increased lean and decreased fat mass of male mice, the latter due to decreased adipocyte size and epididymal, perirenal, and sc adipose weights. A mild improvement in glucose tolerance without a change in insulin sensitivity or secretion aligned with this leaner phenotype. Interestingly, microcomputed tomography analysis indicated that saccharin also increased cortical and trabecular bone mass of male mice and modified cortical bone alone in female mice. A modest increase in circulating testosterone may contribute to the leaner phenotype in male mice. Accordingly, the current study established a developmental period in which saccharin at high concentrations reduces adiposity and increases lean and bone mass in male mice while decreasing generalized growth in female mice.

  19. Height and body composition determine arm propulsive force in youth swimmers independent of a maturation stage.

    PubMed

    Moura, Tatiane; Costa, Manoel; Oliveira, Saulo; Júnior, Marcos Barbosa; Ritti-Dias, Raphael; Santos, Marcos

    2014-09-29

    The aim of this study was to examine the relationship between anthropometric variables, body composition and propulsive force in swimmers aged 9-17 years. Anthropometric characteristics (body height and mass, sitting height, arm span, arm muscle area and body composition) and the propulsive force of the arm (tethered swimming test) were evaluated in 56 competitive male swimmers. Tanner's stages of genital maturation (P1-5) were used. The data analysis included correlations and multiple linear regression. The propulsive force of the arm was correlated with body height (r = 0.34; p =0.013), arm span (r = 0.29; p =0.042), sitting height (r = 0.36; p =0.009), % body fat (r = 0.33; p =0.016), lean body mass (r = 0.34; p =0.015) and arm muscle area (r = 0.31; p =0.026). Using multiple linear regression models, the percent body fat and height were identified as significant predictors of the propulsive force of the arm after controlling for the maturation stage. This model explained 22% (R2 = 0.22) of associations. In conclusion, the propulsive force of swimmers was related to body height and percent body fat. PMID:25414760

  20. Use of a novel pediatric body composition technique for assessing body fatness and its changes during the first 6 month of life

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND: Clinical assessment of infant growth and nutritional status is enhanced by accurate measurement of body composition and its changes over time. OBJECTIVE: To evaluate the accuracy of an air-displacement plethysmograph, the PEA POD (Registered Trademark) Infant Body Composition System (Lif...

  1. Association of maternal smoking with body composition of the newborn.

    PubMed

    Harrison, G G; Branson, R S; Vaucher, Y E

    1983-11-01

    The relationship of maternal cigarette smoking to anthropometric measurements of the newborn was investigated in 285 full-term Caucasian infants. Mothers were classified as "smokers" if they reported smoking both before and during the pregnancy (n = 109) and "nonsmokers" (n = 176). Infants of smoking mothers were significantly lighter, shorter, and had smaller head circumferences, and arm circumferences than those of nonsmokers, consistent with previous findings of other investigators. Ponderal index was not different in the two groups. There was no difference between the two groups in any of the skinfold measurements or in calculated cross-sectional fat area of the upper arm. Multiple regression analyses revealed independent effects of smoking on weight, length, and arm circumference, but no independent effect of smoking on any index of subcutaneous fat. These data suggest that the reduction in birth weight in infants whose mothers who smoke is primarily due to reduction in lean body mass of the newborn while deposition of subcutaneous fat is relatively unaffected.

  2. Crossfit-based high-intensity power training improves maximal aerobic fitness and body composition.

    PubMed

    Smith, Michael M; Sommer, Allan J; Starkoff, Brooke E; Devor, Steven T

    2013-11-01

    The purpose of this study was to examine the effects of a crossfit-based high-intensity power training (HIPT) program on aerobic fitness and body composition. Healthy subjects of both genders (23 men, 20 women) spanning all levels of aerobic fitness and body composition completed 10 weeks of HIPT consisting of lifts such as the squat, deadlift, clean, snatch, and overhead press performed as quickly as possible. Additionally, this crossfit-based HIPT program included skill work for the improvement of traditional Olympic lifts and selected gymnastic exercises. Body fat percentage was estimated using whole-body plethysmography, and maximal aerobic capacity (VO2max) was measured by analyzing expired gasses during a Bruce protocol maximal graded treadmill test. These variables were measured again after 10 weeks of training and compared for significant changes using a paired t-test. Results showed significant (p < 0.05) improvements of VO2max in men (43.10 ± 1.40 to 48.96 ± 1.42 ml · kg · min) and women (35.98 ± 1.60 to 40.22 ± 1.62 ml · kg · min) and decreased body fat percentage in men (22.2 ± 1.3 to 18.0 ± 1.3) and women (26.6 ± 2.0 to 23.2 ± 2.0). These improvements were significant across all levels of initial fitness. Significant correlations between absolute oxygen consumption and oxygen consumption relative to body weight was found in both men (r = 0.83, p < 0.001) and women (r = 0.94, p < 0.001), indicating that HIPT improved VO2max scaled to body weight independent of changes to body composition. Our data show that HIPT significantly improves VO2max and body composition in subjects of both genders across all levels of fitness.

  3. Crossfit-based high-intensity power training improves maximal aerobic fitness and body composition.

    PubMed

    Smith, Michael M; Sommer, Allan J; Starkoff, Brooke E; Devor, Steven T

    2013-11-01

    The purpose of this study was to examine the effects of a crossfit-based high-intensity power training (HIPT) program on aerobic fitness and body composition. Healthy subjects of both genders (23 men, 20 women) spanning all levels of aerobic fitness and body composition completed 10 weeks of HIPT consisting of lifts such as the squat, deadlift, clean, snatch, and overhead press performed as quickly as possible. Additionally, this crossfit-based HIPT program included skill work for the improvement of traditional Olympic lifts and selected gymnastic exercises. Body fat percentage was estimated using whole-body plethysmography, and maximal aerobic capacity (VO2max) was measured by analyzing expired gasses during a Bruce protocol maximal graded treadmill test. These variables were measured again after 10 weeks of training and compared for significant changes using a paired t-test. Results showed significant (p < 0.05) improvements of VO2max in men (43.10 ± 1.40 to 48.96 ± 1.42 ml · kg · min) and women (35.98 ± 1.60 to 40.22 ± 1.62 ml · kg · min) and decreased body fat percentage in men (22.2 ± 1.3 to 18.0 ± 1.3) and women (26.6 ± 2.0 to 23.2 ± 2.0). These improvements were significant across all levels of initial fitness. Significant correlations between absolute oxygen consumption and oxygen consumption relative to body weight was found in both men (r = 0.83, p < 0.001) and women (r = 0.94, p < 0.001), indicating that HIPT improved VO2max scaled to body weight independent of changes to body composition. Our data show that HIPT significantly improves VO2max and body composition in subjects of both genders across all levels of fitness. PMID:23439334

  4. Characterization of body weight and composition changes during the sophomore year of college

    PubMed Central

    Hull, Holly R; Morrow, Michelle L; Dinger, Mary K; Han, Jennifer L; Fields, David A

    2007-01-01

    Background Years spent in college represents a critical time for obesity development though little information is known regarding how body weight and composition changes beyond the first year of college. The aim of this study was to investigate changes in body weight and composition and the factors influencing those changes among sophomore females. Methods Body composition by dual energy X-ray absorptiometry was obtained in participants beginning during their freshman year and continued through their sophomore year. Results No difference was observed between sophomore year fall and spring visits for body weight (60.4 versus 60.6 kg) or fat mass (19.3 versus 18.7 kg). However, a significant (P ≤ 0.05) decrease was observed for body fat (31.9 versus 30.9 %fat) and a significant increase was observed for fat-free mass (37.7 versus 38.4 kg). Participants living off campus significantly (P ≤ 0.05) declined in body fat (33.0 versus 31.0 %fat) and fat mass (19.4 versus 18.2 kg) and increased in fat-free mass (36.1 versus 37.2 kg) with no differences in those living on campus. Conclusion No change in body weight was observed in females during their sophomore year. However, an increase in fat-free mass accompanied with a decrease in fat mass resulted in a decrease in body fat. Participants living off campus had favorable changes in their body composition by means of decreasing %fat and fat mass while increasing fat-free mass. Participants living on campus did not demonstrate these favorable changes. PMID:18028546

  5. Producing Silicon Carbide/Silicon Nitride Fibers

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Manufacturing process makes CxSiyNz fibers. Precursor fibers spun from extruding machine charged with polycarbosilazane resin. When pyrolyzed, resin converted to cross-linked mixture of silicon carbide and silicon nitride, still in fiber form. CxSiyNz fibers promising substitutes for carbon fibers in high-strength, low-weight composites where high electrical conductivity unwanted.

  6. Preparation of silicon carbide fibers

    DOEpatents

    Wei, G.C.

    1983-10-12

    Silicon carbide fibers suitable for use in the fabrication of dense, high-strength, high-toughness SiC composites or as thermal insulating materials in oxidizing environments are fabricated by a new, simplified method wherein a mixture of short-length rayon fibers and colloidal silica is homogenized in a water slurry. Water is removed from the mixture by drying in air at 120/sup 0/C and the fibers are carbonized by (pyrolysis) heating the mixture to 800 to 1000/sup 0/C in argon. The mixture is subsequently reacted at 1550 to 1900/sup 0/C in argon to yield pure ..beta..-SiC fibers.

  7. Anthropometry and body composition of school children in Bahrain

    PubMed Central

    Gharib, Nadia M.; Rasheed, Parveen

    2009-01-01

    BACKGROUND AND OBJECTIVES: This study was conducted because of the lack of a comprehensive nationwide assessment of data on the anthropometric status and related health problems in Bahraini school children aged 6 to 18 years. SUBJECTS AND METHODS: A cross-sectional survey was conducted on the anthropometric status of school children enrolled in the primary, intermediate and secondary government schools in all populated regions of Bahrain. The sample size included 2594 students (1326 girls and 1268 boys) representing 2.5% of the total student population. For sample selection, a multi-stage sampling design was chosen that combined multi-cluster and simple random sampling methods. Anthropometric measurements included height, weight, mid-arm circumference and skin fold thickness at two sites (triceps and subscapular). Anthropometric indices derived were body mass index (BMI) and arm muscle area. The WHO reference standards (2007) and the National Health and Nutrition Examination Survey (NHANES) II data were used for comparison. RESULTS: Compared to WHO reference standards, the median height of Bahraini children and adolescents in the age range of 6 to 18 years was close to the 25th percentile or lower, while the median BMI during adolescent years was comparable in boys, but higher than WHO standards in girls, reaching the 75th percentile. The cut-off values of BMI for overweight/obesity status (85th and 95th percentile) were higher by 3-6 kg/m2 compared to WHO standards. While skin fold thicknesses were also higher in Bahraini adolescents compared to their American counterparts (NHANES II), arm muscularity was substantially lower. CONCLUSIONS: Current study findings for BMI as well as skin fold thicknesses suggest an increased trend toward adiposity among Bahraini adolescents, especially in girls, which puts this age group at a high risk of adult obesity and its consequences. A need for urgent intervention programs is emphasized. PMID:19584585

  8. Effects of ingesting supplements designed to promote lean tissue accretion on body composition during resistance training.

    PubMed

    Kreider, R B; Klesges, R; Harmon, K; Grindstaff, P; Ramsey, L; Bullen, D; Wood, L; Li, Y; Almada, A

    1996-09-01

    This study examined the effects of ingesting nutritional supplements designed to promote lean tissue accretion on body composition alterations during resistance training. Twenty-eight resistance-trained males blindly supplemented their diets with maltodextrin (M), Gainers Fuel 1000 (GF), or Phosphagain (P). No significant differences were observed in absolute or relative total body water among groups. Energy intake and body weight significantly increased in all groups combined throughout the study with no group or interaction differences observed. Dual energy x-ray absorptiometry-determined body mass significantly increased in each group throughout the study with significantly greater gains observed in the GF and P groups. Lean tissue mass (excluding bone) gain was significantly greater in the P group, while fat mass and percent body fat were significantly increased in the GF group. Results indicate that total body weight significantly increased in each group and that P supplementation resulted in significantly greater gains in lean tissue mass during resistance training.

  9. Effects of exercise on fluid exchange and body composition in man during 14-day bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Bernauer, E. M.; Juhos, L. T.; Young, H. L.; Morse, J. T.; Staley, R. W.

    1977-01-01

    A description is presented of an investigation in which body composition, fluid intake, and fluid and electrolyte losses were measured in seven normal, healthy men during three 2-wk bed-rest periods, separated by two 3-wk recovery periods. During bed rest the subjects remained in the horizontal position continuously. During the dietary control periods, body mass decreased significantly with all three regimens, including no exercise, isometric exercise, and isotonic excercise. During bed rest, body mass was essentially unchanged with no exercise, but decreased significantly with isotonic and isometric exercise. With one exception, there were no statistically significant changes in body density, lean body mass, or body fat content by the end of each of the three bed-rest periods.

  10. Comparison of body composition, heart rate variability, aerobic and anaerobic performance between competitive cyclists and triathletes.

    PubMed

    Arslan, Erşan; Aras, Dicle

    2016-04-01

    [Purpose] The aim of this study was to compare the body composition, heart rate variability, and aerobic and anaerobic performance between competitive cyclists and triathletes. [Subjects] Six cyclists and eight triathletes with experience in competitions voluntarily participated in this study. [Methods] The subjects' body composition was measured with an anthropometric tape and skinfold caliper. Maximal oxygen consumption and maximum heart rate were determined using the incremental treadmill test. Heart rate variability was measured by 7 min electrocardiographic recording. The Wingate test was conducted to determine anaerobic physical performance. [Results] There were significant differences in minimum power and relative minimum power between the triathletes and cyclists. Anthropometric characteristics and heart rate variability responses were similar among the triathletes and cyclists. However, triathletes had higher maximal oxygen consumption and lower resting heart rates. This study demonstrated that athletes in both sports have similar body composition and aerobic performance characteristics. PMID:27190476

  11. Comparison of body composition, heart rate variability, aerobic and anaerobic performance between competitive cyclists and triathletes

    PubMed Central

    Arslan, Erşan; Aras, Dicle

    2016-01-01

    [Purpose] The aim of this study was to compare the body composition, heart rate variability, and aerobic and anaerobic performance between competitive cyclists and triathletes. [Subjects] Six cyclists and eight triathletes with experience in competitions voluntarily participated in this study. [Methods] The subjects’ body composition was measured with an anthropometric tape and skinfold caliper. Maximal oxygen consumption and maximum heart rate were determined using the incremental treadmill test. Heart rate variability was measured by 7 min electrocardiographic recording. The Wingate test was conducted to determine anaerobic physical performance. [Results] There were significant differences in minimum power and relative minimum power between the triathletes and cyclists. Anthropometric characteristics and heart rate variability responses were similar among the triathletes and cyclists. However, triathletes had higher maximal oxygen consumption and lower resting heart rates. This study demonstrated that athletes in both sports have similar body composition and aerobic performance characteristics. PMID:27190476

  12. Anthropometric, body composition and performance variables of young elite female basketball players.

    PubMed

    Bale, P

    1991-06-01

    The purpose of the study was to determine the physique and body composition of young female basketball players and to examine these variables in relation to their playing position. Eighteen members of the under seventeen England Basketball squad were measured on twenty different anthropometric sites from which somatotype and body composition were calculated. Four performance measures, vertical jump, anaerobic power, right and left grip strength and laterality were also measured. The variables of the basketball players grouped according to playing position were then compared statistically using ANOVA. Centres had the largest measures of physique and body composition followed by the forwards and then the guards. These differences were significant, particularly between the centres and the guards. The centres were much taller, had longer limb lengths, hip widths and were more muscular.

  13. Body composition in Pan paniscus compared with Homo sapiens has implications for changes during human evolution.

    PubMed

    Zihlman, Adrienne L; Bolter, Debra R

    2015-06-16

    The human body has been shaped by natural selection during the past 4-5 million years. Fossils preserve bones and teeth but lack muscle, skin, fat, and organs. To understand the evolution of the human form, information about both soft and hard tissues of our ancestors is needed. Our closest living relatives of the genus Pan provide the best comparative model to those ancestors. Here, we present data on the body composition of 13 bonobos (Pan paniscus) measured during anatomical dissections and compare the data with Homo sapiens. These comparative data suggest that both females and males (i) increased body fat, (ii) decreased relative muscle mass, (iii) redistributed muscle mass to lower limbs, and (iv) decreased relative mass of skin during human evolution. Comparison of soft tissues between Pan and Homo provides new insights into the function and evolution of body composition.

  14. Body composition in Pan paniscus compared with Homo sapiens has implications for changes during human evolution.

    PubMed

    Zihlman, Adrienne L; Bolter, Debra R

    2015-06-16

    The human body has been shaped by natural selection during the past 4-5 million years. Fossils preserve bones and teeth but lack muscle, skin, fat, and organs. To understand the evolution of the human form, information about both soft and hard tissues of our ancestors is needed. Our closest living relatives of the genus Pan provide the best comparative model to those ancestors. Here, we present data on the body composition of 13 bonobos (Pan paniscus) measured during anatomical dissections and compare the data with Homo sapiens. These comparative data suggest that both females and males (i) increased body fat, (ii) decreased relative muscle mass, (iii) redistributed muscle mass to lower limbs, and (iv) decreased relative mass of skin during human evolution. Comparison of soft tissues between Pan and Homo provides new insights into the function and evolution of body composition. PMID:26034269

  15. Body composition in Pan paniscus compared with Homo sapiens has implications for changes during human evolution

    PubMed Central

    Zihlman, Adrienne L.; Bolter, Debra R.

    2015-01-01

    The human body has been shaped by natural selection during the past 4–5 million years. Fossils preserve bones and teeth but lack muscle, skin, fat, and organs. To understand the evolution of the human form, information about both soft and hard tissues of our ancestors is needed. Our closest living relatives of the genus Pan provide the best comparative model to those ancestors. Here, we present data on the body composition of 13 bonobos (Pan paniscus) measured during anatomical dissections and compare the data with Homo sapiens. These comparative data suggest that both females and males (i) increased body fat, (ii) decreased relative muscle mass, (iii) redistributed muscle mass to lower limbs, and (iv) decreased relative mass of skin during human evolution. Comparison of soft tissues between Pan and Homo provides new insights into the function and evolution of body composition. PMID:26034269

  16. Treatment-Associated Changes in Body Composition, Health Behaviors, and Mood as Predictors of Change in Body Satisfaction in Obese Women: Effects of Age and Race/Ethnicity

    ERIC Educational Resources Information Center

    Annesi, James J.; Tennant, Gisèle A.; Mareno, Nicole

    2014-01-01

    A lack of satisfaction with one's body is common among women with obesity, often prompting unhealthy "dieting." Beyond typically slow improvements in weight and body composition, behavioral factors might also affect change in body satisfaction. Age and race/ethnicity (African American vs. White) might moderate such change. Obese…

  17. Relation between Lifestyle and Socio-Demographic Factors and Body Composition among the Elderly

    PubMed Central

    Zeinali, Fahime; Habibi, Nahal; Samadi, Mehnoosh; Azam, Kamal; Djafarian, Kurosh

    2016-01-01

    Background: Aging is accompanied by various changes that can cause changes in diet and body composition resulting sometimes in malnutrition and disability in the elderly. Changes in body composition among the elderly are mainly the result of physical inactivity and nutrition. This study was designed to examine the relationship between lifestyle and socio-demographic factors and body composition. Method: A cross-sectional study was carried out with 380 elderly people aged 60 and over in district 5 of Tehran, Iran. Their body composition was measured by Bioelectrical Impedance Analysis and the Actigraph device was used for assessing physical activity patterns. A three-day food recall was conducted to measure their intake of energy and macronutrients. Lifestyle and socio-demographic information were collected by interview using a pretested questionnaire. Results: Overweight, obesity and central obesity were more prevalent in women than in men (p<0.001). Moreover, 57.1% and 18.7% of participants had high and very high fat mass index, respectively. High fat mass index was seen in 47% of men and 37.5% of women who had normal body mass index (BMI). Meanwhile, age, gender, physical activity, energy intake, the percentage of energy from fat and protein, educational level, job, television watching time, smoking, chronic diseases, and taking medicine were significantly associated with anthropometric measurements (p<0.05). Conclusion: Overweight, obesity and high body fat percentage were common among the aged. Considering the factors that are significantly associated with body composition, programs that can increase their awareness about the dietary balance and suitable physical activity should be organized to address these problems. PMID:27045408

  18. Noni-based nutritional supplementation and exercise interventions influence body composition

    PubMed Central

    Palu, Afa K.; West, Brett J.; Jensen, Jarakae

    2011-01-01

    Background: The prevalence of obesity and overweight in the Unites States has reached unprecedented levels, and so has the need for effective exercise and nutritional programs for prevention of unhealthy weight gain or safe weight loss. Aims: The present study was conducted in overweight men and women to assess the impact of noni-based nutritional supplementation and exercise interventions on body composition. Materials and Methods: Twenty two participants (16 women and 6 men), ages 18-65, were enrolled in a 12-week, open-label trial of a weight-loss program involving noni-based dietary supplements, gender-specific daily calorie restriction, and exercise interventions. Weight, percent body fat, and body mass index were measured before and after the trial. Results: All participants experienced weight loss. The average decrease in fat mass was highly significant (P < 0.0001), as were decreases in percent body fat and body mass index. Individual weight and fat mass losses were 17.55 ± 9.73 and 21.78 ± 8.34 lbs., respectively, and individual percent body fat and body mass index decreases were 8.91 ± 3.58 % and 2.6 ± 1.32, respectively. Conclusion: The nutritional and exercise interventions significantly influenced body composition among participants. PMID:22363077

  19. Body composition of physically inactive and active 25-month-old female rats.

    PubMed

    Slentz, C A; Holloszy, J O

    1993-07-01

    The purpose of this study was to evaluate the effects of physical activity on the body composition of ageing female rats. Female pathogen-free Long-Evans rats were housed either in individual 7 x 14 x 8 inch cages or in cages with attached running wheels to which they had free access. The runners ate significantly more than the sedentary rats. Food intake from month 10 through month 24 of age averaged 14.6 +/- 0.7 g for the sedentary group, and 18.3 +/- 2.2 g for the active group. The body fat content of the sedentary rats was approximately 50% higher, while their lean body mass and protein content were significantly lower than that of the runners at age 25 months. Total body weight was similar in the active and sedentary groups. Percent body fat and protein of the 25-month-old physically active rats were not significantly different from that of 9-month-old rats, while the sedentary 25-month-old rats had a significantly higher body fat content and a lower body protein content than the 9-month-old animals. These results suggest the possibility that the changes in body composition that occur during middle age in sedentary female rats are largely due to physical inactivity, and that the lean tissue wasting that occurs as the result of the aging process is a late event that occurs closer to the end of life.

  20. Thermal conductivity behavior of boron carbides

    NASA Technical Reports Server (NTRS)

    Wood, C.; Zoltan, A.; Emin, D.; Gray, P. E.

    1983-01-01

    Knowledge of the thermal conductivity of boron carbides is necessary to evaluate its potential for high temperature thermoelectric energy conversion applications. The thermal diffusivity of hot pressed boron carbide B/sub 1-x/C/sub x/ samples as a function of composition, temperature and temperature cycling was measured. These data in concert with density and specific heat data yield the thermal conductivities of these materials. The results in terms of a structural model to explain the electrical transport data and novel mechanisms for thermal conduction are discussed.