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Sample records for oxide fiber targets

  1. Quasar target selection fiber efficiency

    SciTech Connect

    Newberg, H.; Yanny, B.

    1996-05-01

    We present estimates of the efficiency for finding QSOs as a function of limiting magnitude and galactic latitude. From these estimates, we have formulated a target selection strategy that should net 80,000 QSOs in the north galactic cap with an average of 70 fibers per plate, not including fibers reserved for high-redshift quasars. With this plan, we expect 54% of the targets to be QSOs. The North Galactic Cap is divided into two zones of high and low stellar density. We use about five times as many fibers for QSO candidates in the half of the survey with the lower stellar density as we use in the half with higher stellar density. The current plan assigns 15% of the fibers to FIRST radio sources; if these are not available, those fibers would be allocated to lower probability QSO sources, dropping the total number of QSOs by a small factor (5%). We will find about 17,000 additional quasars in the southern strips, and maybe a few more at very high redshift. Use was made of two data sets: the star and quasar simulated test data generated by Don Schneider, and the data from UJFN plate surveys by Koo (1986) and Kron (1980). This data was compared to results from the Palomar-Green Survey and a recent survey by Pat Osmer and collaborators.

  2. Ceramic oxide fibers

    SciTech Connect

    Sowman, H.G.; Johnson, D.D.

    1985-10-01

    Polycrystalline ceramic fibers now available from commercial sources include those of Al/sub 2/O/sub 3/, Al/sub 2/O/sub 3/-SiO/sub 2/O/sub 3/, Al/sub 2/O/sub 3/-B/sub 2/O/sub 3/-SiO/sub 2/, and ZrO/sub 2/-SiO/sub 2/. Continuous filaments in roving, yarn, chopped, bulk, fabric or mat forms can be supplied. Properties and uses of these fibers are discussed. 18 references.

  3. Fiber optic applications for laser polarized targets

    SciTech Connect

    Cummings, W.J.; Kowalczyk, R.S.

    1997-10-01

    For the past two years, the laser polarized target group at Argonne has been used multi-mode fiber optic patch cords for a variety of applications. In this paper, the authors describe the design for transporting high power laser beams with optical fibers currently in use at IUCF.

  4. Polyacrylonitrile fibers containing graphene oxide nanoribbons.

    PubMed

    Chien, An-Ting; Liu, H Clive; Newcomb, Bradley A; Xiang, Changsheng; Tour, James M; Kumar, Satish

    2015-03-11

    Graphene oxide nanoribbon (GONR) made by the oxidative unzipping of multiwalled carbon nanotube was dispersed in dimethylformamide and mixed with polyacrylonitrile (PAN) to fabricate continuous PAN/GONR composite fibers by gel spinning. Subsequently, PAN/GONR composite fibers were stabilized and carbonized in a batch process to fabricate composite carbon fibers. Structure, processing, and properties of the composite precursor and carbon fibers have been studied. This study shows that GONR can be used to make porous precursor and carbon fibers. In addition, GONR also shows the potential to make higher mechanical property carbon fibers than that achieved from PAN precursor only. PMID:25671488

  5. BN Bonded BN fiber article from boric oxide fiber

    DOEpatents

    Hamilton, Robert S.

    1978-12-19

    A boron nitride bonded boron nitride fiber article and the method for its manufacture which comprises forming a shaped article with a composition comprising boron oxide fibers and boric acid, heating the composition in an anhydrous gas to a temperature above the melting point of the boric acid and nitriding the resulting article in ammonia gas.

  6. Conditional knockout of Mn-SOD targeted to type IIB skeletal muscle fibers increases oxidative stress and is sufficient to alter aerobic exercise capacity

    PubMed Central

    Lustgarten, Michael S.; Jang, Youngmok C.; Liu, Yuhong; Muller, Florian L.; Qi, Wenbo; Steinhelper, Mark; Brooks, Susan V.; Larkin, Lisa; Shimizu, Takahiko; Shirasawa, Takuji; McManus, Linda M.; Bhattacharya, Arunabh; Richardson, Arlan

    2009-01-01

    In vitro studies of isolated skeletal muscle have shown that oxidative stress is limiting with respect to contractile function. Mitochondria are a potential source of muscle function-limiting oxidants. To test the hypothesis that skeletal muscle-specific mitochondrial oxidative stress is sufficient to limit muscle function, we bred mice expressing Cre recombinase driven by the promoter for the inhibitory subunit of troponin (TnIFast-iCre) with mice containing a floxed Sod2 (Sod2fl/fl) allele. Mn-SOD activity was reduced by 82% in glycolytic (mainly type II) muscle fiber homogenates from young TnIFastCreSod2fl/fl mice. Furthermore, Mn-SOD content was reduced by 70% only in type IIB muscle fibers. Aconitase activity was decreased by 56%, which suggests an increase in mitochondrial matrix superoxide. Mitochondrial superoxide release was elevated more than twofold by mitochondria isolated from glycolytic skeletal muscle in TnIFastCreSod2fl/fl mice. In contrast, the rate of mitochondrial H2O2 production was reduced by 33%, and only during respiration with complex II substrate. F2-isoprostanes were increased by 36% in tibialis anterior muscles isolated from TnIFastCreSod2fl/fl mice. Elevated glycolytic muscle-specific mitochondrial oxidative stress and damage in TnIFastCreSod2fl/fl mice were associated with a decreased ability of the extensor digitorum longus and gastrocnemius muscles to produce contractile force as a function of time, whereas force production by the soleus muscle was unaffected. TnIFastCreSod2fl/fl mice ran 55% less distance on a treadmill than wild-type mice. Collectively, these data suggest that elevated mitochondrial oxidative stress and damage in glycolytic muscle fibers are sufficient to reduce contractile muscle function and aerobic exercise capacity. PMID:19776389

  7. Indium oxide based fiber optic SPR sensor

    NASA Astrophysics Data System (ADS)

    Shukla, Sarika; Sharma, Navneet K.

    2016-05-01

    Surface plasmon resonance based fiber optic sensor using indium oxide layer is presented and theoretically studied. It has been found that with increase in thickness of indium oxide layer beyond 170 nm, the sensitivity of SPR sensor decreases. 170 nm thick indium oxide layer based SPR sensor holds maximum sensitivity.

  8. Genotoxic mechanisms of asbestos fibers: role of extranuclear targets.

    PubMed

    Xu, An; Huang, Xuelian; Lien, Yu-Chin; Bao, Lingzhi; Yu, Zengliang; Hei, Tom K

    2007-05-01

    Asbestos fibers are carcinogenic to both humans and experimental animals. The continued discoveries of exposure routes whereby the general public is exposed to asbestos suggest a long-term, low-dose exposure for a large number of people. However, the mechanisms by which asbestos induces malignancy are not entirely understood. In previous studies, we have shown that asbestos is an effective gene and chromosomal mutagen when assayed using the highly sensitive AL mutation assay and that the mutagenicity is mediated by reactive oxygen species. The objective of the present study is to determine the origin of these radical species, particularly reactive nitrogen species, in fiber mutagenesis. Using the radical probe 5',6'-chloromethyl-2',7'-dihydroxyphenoxazine diacetate to trap reactive radical species, we showed that crocidolite increased the levels of oxyradicals in cytoplasts, in the absence of the nucleus, in a dose-dependent manner, which was reduced significantly by cotreatment with the radical scavenger dimethyl sulfoxide. Treatment of enucleated cells with crocidolite asbestos followed by rescue fusion using karyoplasts from control cells resulted in significant mutant induction, indicating that the nuclear-cytoplasmic interaction is necessary for fiber mutagenesis. Using the fluorescent probe 2,3-diaminonaphthotriazole, crocidolite fibers were shown to induce a dose-dependent increase of nitric oxide production, which was suppressed significantly by concurrent treatment with the nitric oxide synthase inhibitor, NG-methyl-L-arginine (L-NMMA). Similarly, there was a dose-dependent decrease in the mutation yield induced by crocidolites in the presence of graded doses of L-NMMA. These data showed that extranuclear targets play an essential role in the initiation of oxidative damage that mediates fiber mutagenesis in mammalian cells. PMID:17447795

  9. Oxidation induced stress-rupture of fiber bundles

    SciTech Connect

    Lara-Curzio, E.

    1997-03-01

    The effect of oxidation on the stress-rupture behavior of fiber bundles was modeled. It is shown that oxidation-induced fiber strength degradation results in the delayed failure of the associated fiber bundle and that the fiber bundle strength decreases with time as t{sup {minus}1/4}. It is also shown that the temperature dependence of the bundle loss of strength reflects the thermal dependence of the mechanism controlling the oxidation of the fibers. The effect of gauge length on the fiber bundle strength was also analyzed. Numerical examples are presented for the special case of Nicalon{trademark} fibers.

  10. Strong, damage tolerant oxide-fiber/oxide matrix composites

    NASA Astrophysics Data System (ADS)

    Bao, Yahua

    Electrophoretic deposition (EPD) is an easy and cost effective method to fabricate fiber-reinforced green composites. Non-conductive Nextel(TM) 720 fibers were successfully coated with a transient, conductive polypyrrole submicron surface layer for use directly as an electrode in EPD processing. However, electric-field shielding limits particle infiltration into the conductive fiber bundles and they mostly deposit on the outer surface of the fiber bundle. When the bundle is large, central cavities exist after deposition. The EPD cell was modified for electrophoretic infiltration deposition (EPID). Non conductive fibers were laid on an electrode and charged particles in an ethanol suspension are driven there through by an electric field, infiltrate and deposit on the electrode to then build up into the fiber preform and fill the voids therein. Dense, uniform, green fiber composites were successfully fabricated via constant current EPID. The EPID process is modeled as capillary electrophoretic infiltration. The process consists of two steps: particle electrophoresis outside the capillaries and electrophoretic infiltration inside the capillaries. Due to the zero net flow of the ethanol across the capillary cross-section, there is no electro-osmotic flow contribution to the deposition rate. Hamaker's law was extended to the EPID process, i.e., the deposition yield is proportional to the electric field inside the capillaries. The total deposition yield is controlled by the slow step of the process, i.e., the rate of electrophoresis in the open suspension outside the capillaries. AlPO4 was proposed as a weak layer between oxide fibers and oxide matrix in fiber-reinforced ceramic matrix composites (CMC's). AlPO 4 nano particles were synthesized by chemical co-precipitation of Al 3+ and HPO42- with urea at 95°C. The solution pH basic region and amorphous AlPO4 precipitated of narrow size distribution with a mean particle size 50nm. Nextel 720 fibers were pretreated with

  11. Creep rupture of an oxide/oxide composite fiber

    NASA Astrophysics Data System (ADS)

    Hammond, Vincent Harold

    Due to their low-cost and thermal stability, alumina-based tow-fibers are currently being considered for use in elevated temperature composites. Unfortunately, the fine grain size of the filaments results in extremely poor creep resistance when subjected to high temperature loading. The recent development of a tow-based composite fiber offers a possible solution for improving the creep performance of these materials. To explore the viability of this approach, the creep response of an oxide/oxide composite fiber has been determined through a series of uniaxial creep tests. Despite the high porosity content of the alumina matrix, significant improvements in both steady-state creep rate and creep lifetimes were observed for the composite fibers relative to the as-received tows. The creep strength was found to be strongly sensitive to sintering temperature but only mildly dependent on matrix volume fraction within the range studied. A transition from tough to brittle fracture was also observed in the composite fiber with increasing sintering temperature. An analytical model was developed for predicting the creep response of the as-received Nextel 610 tow. The strain-time history of the tow is generated using the power-law creep rate equation for a Nextel 610 single filament. The failure strain of the tow is predicted using a damage mechanics approach based on a Monkman-Grant type parameter. Predicted values of creep lifetime and failure strain are within 20% of those measured experimentally. The model is then extended to address the creep response of the composite fiber by incorporating the influence of composite fiber architecture, interfacial roughness, and clamping stresses on the reloading of failed filaments.

  12. Fiber optic moisture sensor with moisture-absorbing reflective target

    DOEpatents

    Kirkham, Randy R.

    1987-01-01

    A method and apparatus for sensing moisture changes by utilizing optical fiber technology. One embodiment uses a reflective target at the end of an optical fiber. The reflectance of the target varies with its moisture content and can be detected by a remote unit at the opposite end of the fiber. A second embodiment utilizes changes in light loss along the fiber length. This can be attributed to changes in reflectance of cladding material as a function of its moisture content. It can also be affected by holes or inserts interposed in the cladding material and/or fiber. Changing light levels can also be coupled from one fiber to another in an assembly of fibers as a function of varying moisture content in their overlapping lengths of cladding material.

  13. The high temperature creep behavior of oxides and oxide fibers

    NASA Technical Reports Server (NTRS)

    Jones, Linda E.; Tressler, Richard E.

    1991-01-01

    A thorough review of the literature was conducted on the high-temperature creep behavior of single and polycrystalline oxides which potentially could serve as fiber reinforcements in ceramics or metal matrix applications. Sapphire when oriented with the basal plane perpendicular to the fiber axis (c-axis oriented) is highly creep resistant at temperatures in excess of 1600 C and applied loads of 100 MPa and higher. Pyramidal slip is preferentially activated in sapphire under these conditions and steady-state creep rates in the range of 10(exp -7) to 10 (exp -8)/s were reported. Data on the creep resistance of polycrystalline beryllia suggest that C-axiz oriented single crystal beryllia may be a viable candidate as a fiber reinforcement material; however, the issure of fabricability and moisture sensitivity must be addressed for this material. Yttrium aluminum garnet (YAG) also appears to be a fiber candidate material having a high resistance to creep which is due to it's complex crystal structure and high Peierl resistance. The high creep resistance of garnet suggests that there may be other complex ternary oxides such as single crystal mullite which may also be candidate materials for fiber reinforcements. Finally, CVD and single crystal SiC, although not oxides, do possess a high resistance to creep in the temperature range between 1550 and 1850 C and under stresses of 110 to 220 MPa. From a review of the literature, it appears that for high creep resistant applications sapphire, silicon carbide, yttrium aluminum garnet, mullite, and beryllia are desirable candidate materials which require further investigation.

  14. Characterization and Oxidation Behavior of Rayon-Derived Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan; Hull, David

    2010-01-01

    Rayon-derived fibers are the central constituent of reinforced carbon/ carbon (RCC) composites. Optical, scanning electron, and transmission electron microscopy were used to characterize the as-fabricated fibers and the fibers after oxidation. Oxidation rates were measured with weight loss techniques in air and oxygen. The as-received fibers are approximately 10 micron in diameter and characterized by grooves or crenulations around the edges. Below 800 C, in the reaction-controlled region, preferential attack began in the crenulations and appeared to occur down fissures in the fibers.

  15. Synthesis of Titanium Oxide Nanoparticles by Ytterbium Fiber Laser Ablation

    NASA Astrophysics Data System (ADS)

    Boutinguiza, M.; del Val, J.; Riveiro, A.; Lusquiños, F.; Quintero, F.; Comesaña, R.; Pou, J.

    Nanosized titanium particles have recently received a special attention due to their applications in many different fields, such as catalysis, biomedical engineering, etc. Pulsed laser ablation in liquid media allows obtaining metallic and metallic oxide nanoparticles in colloids. This technique has been used in the present work to prepare titanium colloids from a solid piece immersed in liquid media. A monomode Ytterbium doped fiber laser has been focused onto the upper surface of the titanium target in de-ionized water or ethanol. Crystalline phases, morphology and optical properties of the obtained colloidal nanoparticles were characterized by XRD, HRTEM, and UV/VIS absorption spectroscopy. The produced titanium oxide crystalline nanoparticles show spherical shape and are polycrystalline, exhibiting anatase as well as rutile phases.

  16. Recent developments in polycrystalline oxide fiber laser materials: production of Yb-doped polycrystalline YAG fiber

    NASA Astrophysics Data System (ADS)

    Lee, HeeDong; Keller, Kristin; Sirn, Brian; Parthasarathy, Triplicane; Cheng, Michael; Hopkins, Frank K.

    2011-09-01

    Laser quality, polycrystalline oxide fibers offer significant advantages over state-of-the-art silica fiber for high energy lasers. Advanced ceramic processing technology, along with a novel powder production process, has potential to produce oxide fibers with an outstanding optical quality for use in the fiber laser applications. The production of contaminant-free green fibers with a high packing density, as well as uniform packing distribution, is a key factor in obtaining laserquality fibers. High quality green fibers are dependent on the powder quality combined with the appropriate slurry formulation. These two fundamental technologies were successfully developed at UES, and used to produce Yb-doped yttrium aluminum garnet (YAG) fibers with high optical quality, high chemical purity, and suitable core diameters down to 20-30 microns.

  17. A comparison of fiber effects on polymer matrix composite oxidation

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.

    1991-01-01

    A number of thermo-oxidative stability studies addressing the effects of fiber reinforcement on composite thermal stability and influence of geometry on the results of aging studies were performed at NASA-Lewis. The information presented herein, a compilation of some results from these studies, shows the influence of the reinforcement fibers on the oxidative degradation of various PMR-15 composites. Reinforcement of graphite and ceramics were studied and three composite oxidation mechanisms were observed. One was a dominant attack of the reinforcement fiber, the second was the aggressive oxidation of the matrix material, and the third was interfacial degradation.

  18. The muscle fiber type–fiber size paradox: hypertrophy or oxidative metabolism?

    PubMed Central

    van Wessel, T.; de Haan, A.; van der Laarse, W. J.

    2010-01-01

    An inverse relationship exists between striated muscle fiber size and its oxidative capacity. This relationship implies that muscle fibers, which are triggered to simultaneously increase their mass/strength (hypertrophy) and fatigue resistance (oxidative capacity), increase these properties (strength or fatigue resistance) to a lesser extent compared to fibers increasing either of these alone. Muscle fiber size and oxidative capacity are determined by the balance between myofibrillar protein synthesis, mitochondrial biosynthesis and degradation. New experimental data and an inventory of critical stimuli and state of activation of the signaling pathways involved in regulating contractile and metabolic protein turnover reveal: (1) higher capacity for protein synthesis in high compared to low oxidative fibers; (2) competition between signaling pathways for synthesis of myofibrillar proteins and proteins associated with oxidative metabolism; i.e., increased mitochondrial biogenesis via AMP-activated protein kinase attenuates the rate of protein synthesis; (3) relatively higher expression levels of E3-ligases and proteasome-mediated protein degradation in high oxidative fibers. These observations could explain the fiber type–fiber size paradox that despite the high capacity for protein synthesis in high oxidative fibers, these fibers remain relatively small. However, it remains challenging to understand the mechanisms by which contractile activity, mechanical loading, cellular energy status and cellular oxygen tension affect regulation of fiber size. Therefore, one needs to know the relative contribution of the signaling pathways to protein turnover in high and low oxidative fibers. The outcome and ideas presented are relevant to optimizing treatment and training in the fields of sports, cardiology, oncology, pulmonology and rehabilitation medicine. Electronic supplementary material The online version of this article (doi:10.1007/s00421-010-1545-0) contains

  19. Crystal-free Formation of Non-Oxide Optical Fiber

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy A.

    2015-01-01

    Researchers at NASA Marshall Space Flight Center have devised a method for the creation of crystal-free nonoxide optical fiber preforms. Non-oxide fiber optics are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. However, some of these glasses are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. NASA has developed a new method of non-oxide fiber formation that uses axial magnetic fields to suppress crystallization. The resulting non-oxide fibers are crystal free and have lower signal attenuation rates than silica based optical fibers.

  20. Preparation of anti-oxidative carbon fiber at high temperature

    NASA Astrophysics Data System (ADS)

    Kim, Bo-Hye; Kim, Su Yeun; Kim, Chang Hyo; Yang, Kap Seung; Lee, Young-Jun

    2010-11-01

    In this paper, carbon fibers with improved thermal stability and oxidation resistive properties were prepared and evaluated their physical performances under oxidation condition. Carbon fibers were coated with SiC particles dispersed in a polyacrylonitrile solution and then followed by pyrolyzed at 1400 °C to obtain the SiC nanoparticle deposition on the surface of the carbon fiber. The SiC coated carbon fiber showed extended oxidation resistive property as remaining 80-88% of the original weight even at high temperature 1000 °C under air, as compared with the control of zero weight at 600 °C. The effects of the coating conditions on the oxidation resistive properties of the coated fibers were studied in detail.

  1. Oxidation of Carbon Fibers in Water Vapor Studied

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.

    2003-01-01

    T-300 carbon fibers (BP Amoco Chemicals, Greenville, SC) are a common reinforcement for silicon carbide composite materials, and carbon-fiber-reinforced silicon carbide composites (C/SiC) are proposed for use in space propulsion applications. It has been shown that the time to failure for C/SiC in stressed oxidation tests is directly correlated with the fiber oxidation rate (ref. 1). To date, most of the testing of these fibers and composites has been conducted in oxygen or air environments; however, many components for space propulsion, such as turbopumps, combustors, and thrusters, are expected to operate in hydrogen and water vapor (H2/H2O) environments with very low oxygen contents. The oxidation rate of carbon fibers in conditions representative of space propulsion environments is, therefore, critical for predicting component lifetimes for real applications. This report describes experimental results that demonstrate that, under some conditions, lower oxidation rates of carbon fibers are observed in water vapor and H2/H2O environments than are found in oxygen or air. At the NASA Glenn Research Center, the weight loss of the fibers was studied as a function of water pressure, temperature, and gas velocity. The rate of carbon fiber oxidation was determined, and the reaction mechanism was identified.

  2. Interactions between the glass fiber coating and oxidized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ku-Herrera, J. J.; Avilés, F.; Nistal, A.; Cauich-Rodríguez, J. V.; Rubio, F.; Rubio, J.; Bartolo-Pérez, P.

    2015-03-01

    Chemically oxidized multiwall carbon nanotubes (MWCNTs) were deposited onto commercial E-glass fibers using a dipping procedure assisted by ultrasonic dispersion. In order to investigate the role of the fiber coating (known as "sizing"), MWCNTs were deposited on the surface of as-received E-glass fibers preserving the proprietary coating as well as onto glass fibers which had the coating deliberately removed. Scanning electron microscopy and Raman spectroscopy were used to assess the distribution of MWCNTs onto the fibers. A rather homogeneous coverage with high density of MWCNTs onto the glass fibers is achieved when the fiber coating is maintained. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) analyses of the chemical composition of the glass fiber coating suggest that such coating is a complex mixture with multiple oxygen-containing functional groups such as hydroxyl, carbonyl and epoxy. FTIR and XPS of MWCNTs over the glass fibers and of a mixture of MWCNTs and fiber coating provided evidence that the hydroxyl and carboxyl groups of the oxidized MWCNTs react with the oxygen-containing functional groups of the glass fiber coating, forming hydrogen bonding and through epoxy ring opening. Hydrogen bonding and ester formation between the functional groups of the MWCNTs and the silane contained in the coating are also possible.

  3. Eliminating crystals in non-oxide optical fiber preforms and optical fibers

    NASA Technical Reports Server (NTRS)

    LaPointe, Michael R. (Inventor); Tucker, Dennis S. (Inventor)

    2010-01-01

    A method is provided for eliminating crystals in non-oxide optical fiber preforms as well as optical fibers drawn therefrom. The optical-fiber-drawing axis of the preform is aligned with the force of gravity. A magnetic field is applied to the preform as it is heated to at least a melting temperature thereof. The magnetic field is applied in a direction that is parallel to the preform's optical-fiber-drawing axis. The preform is then cooled to a temperature that is less than a glass transition temperature of the preform while the preform is maintained in the magnetic field. When the processed preform is to have an optical fiber drawn therefrom, the preform's optical-fiber-drawing axis is again aligned with the force of gravity and a magnetic field is again applied along the axis as the optical fiber is drawn from the preform.

  4. Oxidation-induced contraction and strengthening of boron fibers

    NASA Technical Reports Server (NTRS)

    Dicarlo, J. A.; Wagner, T. C.

    1981-01-01

    An investigation was conducted to measure and understand the physical and mechanical effects that occur in boron fibers during and after thermal treatment in a controlled oxygen argon gaseous mixture. Of principal concern was the optimization of this treatment as a secondary processing method for significantly improving fiber tensile strength. Strengthening was accomplished by an oxidation induced axial contraction of the fiber and a resulting axial compression of strength limiting flaws within the fiber's tungsten boride core. Various physical observations were used to develop mechanistic models for oxidation, contraction, and flow formation. Processing guidelines are discussed for possibly exceeding the 5.5 GN/sq m strength limit and also for achieving fiber strengthening during application of boron containing diffusion barrier coatings.

  5. Target allocation yields for massively multiplexed spectroscopic surveys with fibers

    SciTech Connect

    Saunders, Will; Smedley, Scott; Gillingham, Peter; Forero-Romero, Jaime E.; Jouvel, Stephanie; Nord, Brian

    2014-08-05

    We present Simulated Annealing fiber-to-target allocation simulations for the proposed DESI and 4MOST massively multiplexed spectroscopic surveys, and for both Poisson and realistically clustered mock target samples. We simulate both Echidna and theta-phi actuator designs, including the restrictions caused by the physical actuator characteristics during repositioning. For DESI, with theta-phi actuators, used in 5 passes over the sky for a mock ELG/LRG/QSO sample, with matched fiber and target densities, a total target allocation yield of 89.3% was achieved, but only 83.7% for the high-priority Ly-alpha QSOs. If Echidna actuators are used with the same pitch and number of passes, the yield increases by 5.7% and 16% respectively. Echidna also allows a factor-of-two increase in the number of close Ly-alpha QSO pairs that can be observed. Echidna spine tilt causes a variable loss of throughput, with average loss being the same as the loss at the rms tilt. With a natural tilt minimization scheme, we find an rms tilt always close to 0.58 x maximum. There is an additional but much smaller defocus loss, equivalent to an average defocus of 30microns. These tilt losses offset the gains in yield for Echidna, but because the survey strategy is driven by the higher priority targets, a clear survey speed advantage remains. For 4MOST, high and low latitude sample mock catalogs were supplied by the 4MOST team, and allocations were carried out with the proposed Echidna-based positioner geometry. At high latitudes, the resulting target completeness was 85.3% for LR targets and 78.9% for HR targets. At low latitude, the target completeness was 93.9% for LR targets and 71.2% for HR targets.

  6. Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

    DOEpatents

    Wrenn, Jr., George E.; Holcombe, Jr., Cressie E.

    1988-01-01

    A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

  7. Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

    DOEpatents

    Wrenn, G.E. Jr.; Holcombe, C.E. Jr.

    1988-09-13

    A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

  8. Oxidation-resistant interfacial coatings for continuous fiber ceramic composites

    SciTech Connect

    Stinton, D.P.; Besmann, T.M.; Bleier, A.; Shanmugham, S.; Liaw, P.K.

    1995-08-01

    Continuous fiber ceramic composites mechanical behavior are influenced by the bonding characteristics between the fiber and the matrix. Finite modeling studies suggest that a low-modulus interfacial coating material will be effective in reducing the residual thermal stresses that are generated upon cooling from processing temperatures. Nicalon{trademark}/SiC composites with carbon, alumina and mullite interfacial coatings were fabricated with the SiC matrix deposited using a forced-flow, thermal gradient chemical vapor infiltration process. Composites with mullite interfacial coatings exhibited considerable fiber pull-out even after oxidation and have potential as a composite system.

  9. Carbon and oxide coatings on continuous ceramic fibers

    SciTech Connect

    Hay, R.S.; Cinibulk, M.K.; Petry, M.D.; Keller, K.A.; Welch, J.R.

    1995-10-01

    Oxide-carbon multilayer coatings were continuously applied to various fibers of nominal SiC composition. A liquid-phase coating system that allows application of the coatings in a controlled atmosphere at relatively rapid rates was employed. Sugar-ammonium hydroxide solutions were used for carbon coatings, and aqueous sols were used for the oxides. Carbon was also deposited simultaneously with alumina by chemical vapor deposition of a hydrocarbon in the coating furnace. The coatings were extensively characterized by optical microscopy and TEM. Problems with embrittlement by oxide coatings and poor adherence of oxide coatings on carbon, and some possible solutions to these problems, are discussed.

  10. Recent developments in zinc oxide target chemistry

    SciTech Connect

    Heaton, R.C.; Taylor, W.A.; Phillips, D.R.; Jamriska, D.J. Sr.; Garcia, J.B.

    1994-04-01

    Zinc oxide targets irradiated with high energy protons at the Los Alamos Meson Physics Facility (LAMPF) contain a number of radioactive spallation products in quantities large enough to warrant recovery. This paper describes methods for recovering {sup 7}Be, {sup 46}Sc, and {sup 48}V from such targets and offers suggestions on possible ways to recover additional isotopes. The proposed methods are based on traditional precipitation and ion exchange techniques, are readily adaptable to hot cell use, and produce no hazardous waste components. The products are obtained in moderate to high yields and have excellent radiopurity.

  11. Target allocation yields for massively multiplexed spectroscopic surveys with fibers

    NASA Astrophysics Data System (ADS)

    Saunders, Will; Smedley, Scott; Gillingham, Peter; Forero-Romero, Jaime E.; Jouvel, Stephanie; Nord, Brian

    2014-08-01

    We present Simulated Annealing fiber-to-target allocation simulations for the proposed DESI and 4MOST massively multiplexed spectroscopic surveys. We simulate various survey strategies, for both Poisson and realistically clustered mock target samples. We simulate both Echidna and theta-phi actuator designs, including the restrictions caused by the physical actuator characteristics during repositioning. For DESI, with theta-phi actuators, used in 5 passes over the sky for a mock ELG/LRG/QSO sample, with matched fiber and target densities, a total target allocation yield of 89.3% was achieved, but only 83.7% for the high-priority Ly-alpha QSOs. If Echidna actuators are used with the same pitch and number of passes, the yield increases to 94.4% and 97.2% respectively, representing fractional gains of 5.7% and 16% respectively. Echidna also allows a factor-of-two increase in the number of close Ly-alpha QSO pairs that can be observed. Echidna spine tilt causes a variable loss of throughput, with average loss being the same as the loss at the rms tilt. The simulated annealing allows spine tilt minimization to be included in the optimization, at some small cost to the yield. With a natural minimization scheme, we find an rms tilt always close to 0.58 x maximum. There is an additional but much smaller defocus loss, equivalent to an average defocus of 30 μm. These tilt losses offset the gains in yield for Echidna, but because the survey strategy is driven by the higher priority targets, a clear survey speed advantage remains. For 4MOST, high and low latitude sample mock catalogs were supplied by the 4MOST team, and allocations were carried out with the proposed Echidna-based positioner geometry. At high latitudes, the resulting target completeness was 85.3% for LR targets and 78.9% for HR targets. At low latitude, the target completeness was 93.9% for LR targets and 71.2% for HR targets.

  12. Production of graphene oxide from pitch-based carbon fiber

    NASA Astrophysics Data System (ADS)

    Lee, Miyeon; Lee, Jihoon; Park, Sung Young; Min, Byunggak; Kim, Bongsoo; in, Insik

    2015-07-01

    Pitch-based graphene oxide (p-GO) whose compositional/structural features are comparable to those of graphene oxide (GO) was firstly produced by chemical exfoliation of pitch-based carbon fiber rather than natural graphite. Incorporation of p-GO as nanofillers into poly(methyl methacrylate) (PMMA) as a matrix polymer resulted in excellent mechanical reinforcement. p-GO/PMMA nanocomposite (1 wt.-% p-GO) demonstrated 800% higher modulus of toughness of neat PMMA.

  13. Production of graphene oxide from pitch-based carbon fiber

    PubMed Central

    Lee, Miyeon; Lee, Jihoon; Park, Sung Young; Min, Byunggak; Kim, Bongsoo; In, Insik

    2015-01-01

    Pitch-based graphene oxide (p-GO) whose compositional/structural features are comparable to those of graphene oxide (GO) was firstly produced by chemical exfoliation of pitch-based carbon fiber rather than natural graphite. Incorporation of p-GO as nanofillers into poly(methyl methacrylate) (PMMA) as a matrix polymer resulted in excellent mechanical reinforcement. p-GO/PMMA nanocomposite (1 wt.-% p-GO) demonstrated 800% higher modulus of toughness of neat PMMA. PMID:26156067

  14. Interphase for ceramic matrix composites reinforced by non-oxide ceramic fibers

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A. (Inventor); Bhatt, Ramakrishna (Inventor); Morscher, Gregory N. (Inventor); Yun, Hee-Mann (Inventor)

    2008-01-01

    A ceramic matrix composite material is disclosed having non-oxide ceramic fibers, which are formed in a complex fiber architecture by conventional textile processes; a thin mechanically weak interphase material, which is coated on the fibers; and a non-oxide or oxide ceramic matrix, which is formed within the interstices of the interphase-coated fiber architecture. During composite fabrication or post treatment, the interphase is allowed to debond from the matrix while still adhering to the fibers, thereby providing enhanced oxidative durability and damage tolerance to the fibers and the composite material.

  15. Oxidation of Al2O3 continuous fiber-reinforced/NiAl composites

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Nesbitt, J. A.; Noebe, R. D.; Bowman, R. R.

    1992-01-01

    The 1200 C and 1300 C isothermal and cyclic oxidation behavior of Al2O3 continuous fiber-reinforced/NiAl composites were studied. Oxidation resulted in formation of Al2O3 external scales in a similar manner as scales formed on monolithic NiAl. The isothermal oxidation of an Al2O3/NiAl composite resulted in oxidation of the matrix along the fiber/matrix interface near the fiber ends. This oxide acted as a wedge between the fiber and the matrix, and, under cyclic oxidation conditions, led to further oxidation along the fiber lengths and eventual cracking of the composite. The oxidation behavior of composites in which the Al2O3 fibers were sputter coated with nickel prior to processing was much more severe. This was attributed to open channels around the fibers which formed during processing, most likely as a result of the diffusion of the nickel coating into the matrix.

  16. Oxidation Behavior of Carbon Fiber-Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Sullivan, Roy M.

    2008-01-01

    OXIMAP is a numerical (FEA-based) solution tool capable of calculating the carbon fiber and fiber coating oxidation patterns within any arbitrarily shaped carbon silicon carbide composite structure as a function of time, temperature, and the environmental oxygen partial pressure. The mathematical formulation is derived from the mechanics of the flow of ideal gases through a chemically reacting, porous solid. The result of the formulation is a set of two coupled, non-linear 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 at each time step using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The non-linear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual finite element method, allowing for the solution of the differential equations numerically.

  17. Eliminating Crystals in Non-Oxide Optical Fiber Preforms and Optical Fibers

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; LaPointe, Michael R.

    2012-01-01

    Non ]oxide fiber optics such as heavy metal fluoride and chalcogenide glasses are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. The addition of rare earths such as erbium, enable these materials to be used as fiber laser and amplifiers. Some of these glasses however are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. Previously two research teams found that microgravity suppressed crystallization in heavy metal fluoride glasses. Looking for a less expensive method to suppress crystallization, ground based research was performed utilizing an axial magnetic field. The experiments revealed identical results to those obtained via microgravity processing. This research then led to a patented process for eliminating crystals in optical fiber preforms and the resulting optical fibers. In this paper, the microgravity results will be reviewed as well as patents and papers relating to the use of magnetic fields in various material and glass processing applications. Finally our patent to eliminate crystals in non ]oxide glasses utilizing a magnetic field will be detailed.

  18. Various-sourced pectin and polyethylene oxide electrospun fibers.

    PubMed

    Rockwell, Pamela L; Kiechel, Marjorie A; Atchison, Jennifer S; Toth, Laura J; Schauer, Caroline L

    2014-07-17

    Pectin, a naturally occurring and biorenewable polysaccharide, is derived from plant cell wall tissue and used in applications ranging from food processing to biomedical engineering. Due to extraction methods and source variation, there is currently no consensus in literature as to the exact structure of pectin. Here, we have studied key material properties of electrospun pectin blends with polyethylene oxide (PEO) (1:1, v/v) in order to demonstrate the fabrication of a fibrous and less toxic material system, as well as to understand the effects of source variability on the resulting fibrous mats. The bulk pectin degree of esterification (DE) estimated using FTIR (bulk apple pomace (AP)=28%, bulk citrus peel (CP)=86% and bulk sugar beet pulp (SBP)=91%) was shown to inversely correlate with electrospun fiber crystallinity determined using XRD (PEO-AP=37%, PEO-CP=28% and PEO-SBP=23%). This in turn affected the trend observed for the mean fiber diameter (n=50) (PEO-AP=124 ± 26 nm, PEO-CP=493 ± 254 nm and PEO-SBP=581 ± 178 nm) and elastic tensile moduli (1.6 ± 0.2 MPa, 4.37 ± 0.64 MPa and 2.49 ± 1.46 MPa, respectively) of the fibrous mats. Electrospun fibers containing bulk AP had the lowest DE, highest crystallinity, smallest mean fiber diameter, and lowest tensile modulus compared to either the bulk CP or bulk SBP. Bound water in PEO-CP fiber and bulk pectin impurities in PEO-SPB were observed to influence fiber branching and mean diameter distributions, which in turn influenced the fiber tensile properties. These results indicate that pectin, when blended with PEO in water, produces submicron fibrous mats with pectin influencing the blend fiber properties. Moreover, the source of pectin is an important variable in creating electrospun blend fibrous mats with desired material properties. PMID:24702925

  19. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection.

    PubMed

    Yao, B C; Wu, Y; Yu, C B; He, J R; Rao, Y J; Gong, Y; Fu, F; Chen, Y F; Li, Y R

    2016-01-01

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel 'FRET on Fiber' concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based 'FRET on fiber' configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated 'FRET on Fiber' sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response. PMID:27010752

  20. Bismuth oxide nanotubes-graphene fiber-based flexible supercapacitors

    NASA Astrophysics Data System (ADS)

    Gopalsamy, Karthikeyan; Xu, Zhen; Zheng, Bingna; Huang, Tieqi; Kou, Liang; Zhao, Xiaoli; Gao, Chao

    2014-07-01

    Graphene-bismuth oxide nanotube fiber as electrode material for constituting flexible supercapacitors using a PVA/H3PO4 gel electrolyte is reported with a high specific capacitance (Ca) of 69.3 mF cm-2 (for a single electrode) and 17.3 mF cm-2 (for the whole device) at 0.1 mA cm-2, respectively. Our approach opens the door to metal oxide-graphene hybrid fibers and high-performance flexible electronics.Graphene-bismuth oxide nanotube fiber as electrode material for constituting flexible supercapacitors using a PVA/H3PO4 gel electrolyte is reported with a high specific capacitance (Ca) of 69.3 mF cm-2 (for a single electrode) and 17.3 mF cm-2 (for the whole device) at 0.1 mA cm-2, respectively. Our approach opens the door to metal oxide-graphene hybrid fibers and high-performance flexible electronics. Electronic supplementary information (ESI) available: Equations and characterization. SEM images of GGO, XRD and XPS of Bi2O3 NTs, HRTEM images and EDX Spectra of Bi2O3 NT5-GF, CV curves of Bi2O3NT5-GF, Bi2O3 NTs and bismuth nitrate in three-electrode system (vs. Ag/AgCl). CV and GCD curves of Bi2O3 NT1-GF and Bi2O3 NT3-GF. See DOI: 10.1039/c4nr02615b

  1. Effect of fiber reinforcements on thermo-oxidative stability and mechanical properties of polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.

    1991-01-01

    A number of studies have investigated the thermo-oxidative behavior of polymer matrix composites. Two significant observations have been made from these research efforts: (1) fiber reinforcement has a significant effect on composite thermal stability; and (2) geometric effects must be considered when evaluating thermal aging data. A compilation of some results from these studies is presented, and this information shows the influence of the reinforcement fibers on the oxidative degradation of various polymer matrix composites. The polyimide PMR-15 was the matrix material that was used in these studies. The control composite material was reinforced with Celion 6000 graphite fiber. T-40R graphite fibers, along with some very stable ceramic fibers were selected as reinforcing fibers because of their high thermal stability. The ceramic fibers were Nicalon (silicon carbide) and Nextel 312 (alumina-silica-boron oxide). The mechanical properties of the two graphite fiber composites were significantly different, probably owing to variations in interfacial bonding between the fibers and the polyimide matrix. The Celion 6000/PMR-15 bond is very tight but the T-40/PMR-15 bond is less tight. Three oxidation mechanisms were observed: (1) the preferential oxidation of the Celion 6000 fiber ends at cut surfaces, leaving a surface of matrix material with holes where the fiber ends were originally situated; (2) preferential oxidation of the composite matrix; and (3) interfacial degradation by oxidation. The latter two mechanisms were also observed on fiber end cut surfaces. The fiber and interface attacks appeared to initiate interfiber cracking along these surfaces.

  2. 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.

  3. Methionine oxidation reduces lag-times for amyloid-β(1-40) fiber formation but generates highly fragmented fibers.

    PubMed

    Gu, Miao; Viles, John H

    2016-09-01

    Oxidative stress and the formation of amyloid plaques containing amyloid-β (Aβ) peptides are two key hallmarks of Alzheimer's disease. A proportion of methionine (Met) at position 35 within Aβ is oxidized to methionine sulphoxide (Met(OX)) within the Alzheimer's plaques. These oxidative processes may be the key to understanding the early stages of Alzheimer's disease. In vitro oxidation of Aβ, by the physiological oxidant H2O2, was monitored using (1)H NMR and mass spectrometry. Here we investigate the effect of Aβ methionine oxidation on fiber formation kinetics and morphology using the amyloid specific fluorescence dye Thioflavin T (ThT) and Transmission Electron Microscopy (TEM). Methionine oxidation reduces the total amount of fibers generated for both dominant forms of Aβ, however there are marked differences in the effect of Met(OX) between Aβ(1-40) and Aβ(1-42). Surprisingly the presence of Met(OX) reduces lag-times for Aβ(1-40) fiber formation but extends lag-times for Aβ(1-42). TEM indicates a change in fiber morphology with a pronounced reduction in fiber length for both methionine oxidized Aβ(1-40) and Aβ(1-42). In contrast, the morphology of preformed amyloid fibers is largely unaffected by the presence of H2O2. Our studies suggest that methionine oxidation promotes highly fragmented fiber assemblies of Aβ. Oxidative stress associated with Alzheimer's disease can cause oxidation of methionine within Aβ and this in turn will influence the complex assembly of Aβ monomer into amyloid fibers, which is likely to impact Aβ toxicity. PMID:27108954

  4. A scintillating fiber-optic active target (SFT) for studies of high energy photoproduction

    SciTech Connect

    Ruchti, R.; Baumbaugh, B.; Bishop, J.; Busenitz, J.; Cason, N.; Cunningham, J.; Gardner, R.; Kennedy, C.; Mannel, E.; Mountain, R.J.

    1988-02-01

    A high resolution, gateable, Scintillating Fiber Target (SFT) has been developed for Fermilab Experiment E687 to study charm and beauty particle production and decay in high energy photon interactions. The detector consists of a scintillating target of either GS1 Cerium glass fibers or polystyrene fibers of 29..mu..m cross section, a multi-stage image intensifier and an intensified CCD or SIT/VIDICON camera system used in conjunction with a custom-built video data acquisition system.

  5. A novel electrospinning target to improve the yield of uniaxially aligned fibers.

    PubMed

    Secasanu, Virgil P; Giardina, Christopher K; Wang, Yadong

    2009-01-01

    Electrospinning is a useful technique that can generate micro and nanometer-sized fibers. Modification of the electrospinning parameters, such as deposition target geometry, can generate uniaxially aligned fibers for use in diverse applications ranging from tissue engineering to material fabrication. For example, meshes of fibers have been shown to mimic the extracellular matrix networks for use in smooth muscle cell proliferation. Further, aligned fibers can guide neurites to grow along the direction of the fibers. Here we present a novel electrospinning deposition target that combines the benefits of two previously reported electrodes: the standard parallel electrodes and the spinning wheel with a sharpened edge. This new target design significantly improves aligned fiber yield. Specifically, the target consists of two parallel aluminum plates with sharpened edges containing a bifurcating angle of 26 degrees. Electric field computations show a larger probable area of aligned electric field vectors. This new deposition target allows fibers to deposit on a larger cross-sectional area relative to the existing parallel electrode and at least doubles the yield of uniaxially aligned fibers. Further, fiber alignment and morphology are preserved after collection from the deposition target. PMID:19562742

  6. Respirometric Oxidative Phosphorylation Assessment in Saponin-permeabilized Cardiac Fibers

    PubMed Central

    Hughey, Curtis C.; Hittel, Dustin S.; Johnsen, Virginia L.; Shearer, Jane

    2011-01-01

    Investigation of mitochondrial function represents an important parameter of cardiac physiology as mitochondria are involved in energy metabolism, oxidative stress, apoptosis, aging, mitochondrial encephalomyopathies and drug toxicity. Given this, technologies to measure cardiac mitochondrial function are in demand. One technique that employs an integrative approach to measure mitochondrial function is respirometric oxidative phosphorylation (OXPHOS) analysis. The principle of respirometric OXPHOS assessment is centered around measuring oxygen concentration utilizing a Clark electrode. As the permeabilized fiber bundle consumes oxygen, oxygen concentration in the closed chamber declines. Using selected substrate-inhibitor-uncoupler titration protocols, electrons are provided to specific sites of the electron transport chain, allowing evaluation of mitochondrial function. Prior to respirometric analysis of mitochondrial function, mechanical and chemical preparatory techniques are utilized to permeabilize the sarcolemma of muscle fibers. Chemical permeabilization employs saponin to selectively perforate the cell membrane while maintaining cellular architecture. This paper thoroughly describes the steps involved in preparing saponin-skinned cardiac fibers for oxygen consumption measurements to evaluate mitochondrial OXPHOS. Additionally, troubleshooting advice as well as specific substrates, inhibitors and uncouplers that may be used to determine mitochondria function at specific sites of the electron transport chain are provided. Importantly, the described protocol may be easily applied to cardiac and skeletal tissue of various animal models and human samples. PMID:21403632

  7. Sensor materials for an intravascular fiber optic nitric oxide sensor

    NASA Astrophysics Data System (ADS)

    Soller, Babs R.; Parikh, Bhairavi R.; Stahl, Russell F.

    1996-04-01

    Nitric oxide (NO) is an important regulatory molecule in physiological processes including neurotransmission and the control of blood pressure. It is produced in excess during septic shock, the profound hypotensive state which accompanies severe infections. In-vivo measurement of NO would enhance the understanding of its varied biological roles. Our goal is the development of an intravascular fiber-optic sensor for the continuous measurement of NO. This study evaluated nitric oxide sensitive compounds as potential sensing materials in the presence and absence of oxygen. Using absorption spectroscopy we studied both the Fe II and Fe III forms of three biologically active hemes known to rapidly react with NO: hemoglobin, myoglobin, and cytochrome-c. The Fe II forms of hemoglobin and myoglobin and the Fe III form of cytochrome-c were found to have the highest sensitivity to NO. Cytochrome c (Fe III) is selective for NO even at high oxygen levels, while myoglobin is selective only under normal oxygen levels. NO concentrations as low as 1 (mu) M can be detected with our fiber-optic spectrometer using cytochrome c, and as low as 300 nM using myoglobin. Either of these materials would be adequate to monitor the increase in nitric oxide production during the onset of septic shock.

  8. Effects of Temperature, Oxidation and Fiber Preforms on Fatigue Life of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-08-01

    In this paper, the effects of temperature, oxidation and fiber preforms on the fatigue life of carbon fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) have been investigated. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface wear model and fibers statistical failure model at room temperature, and interface/fibers oxidation model, interface wear model and fibers statistical failure model at elevated temperatures in the oxidative environments. When the broken fibers fraction approaches to the critical value, the composites fatigue fracture. The fatigue life S-N curves and fatigue limits of unidirectional, cross-ply, 2D, 2.5D and 3D C/SiC composites at room temperature, 800 °C in air, 1100, 1300 and 1500 °C in vacuum conditions have been predicted.

  9. Effects of Temperature, Oxidation and Fiber Preforms on Fatigue Life of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-04-01

    In this paper, the effects of temperature, oxidation and fiber preforms on the fatigue life of carbon fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) have been investigated. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface wear model and fibers statistical failure model at room temperature, and interface/fibers oxidation model, interface wear model and fibers statistical failure model at elevated temperatures in the oxidative environments. When the broken fibers fraction approaches to the critical value, the composites fatigue fracture. The fatigue life S-N curves and fatigue limits of unidirectional, cross-ply, 2D, 2.5D and 3D C/SiC composites at room temperature, 800 °C in air, 1100, 1300 and 1500 °C in vacuum conditions have been predicted.

  10. Fiber optic relative humidity sensor based on the tilted fiber Bragg grating coated with graphene oxide

    NASA Astrophysics Data System (ADS)

    Wang, Youqing; Shen, Changyu; Lou, Weimin; Shentu, Fengying; Zhong, Chuan; Dong, Xinyong; Tong, Limin

    2016-07-01

    A fiber optic relative humidity (RH) sensor based on the tilted fiber Bragg grating (TFBG) coated with graphene oxide (GO) film was presented. Amplitudes of the cladding mode resonances of the TFGB varies with the water sorption and desorption processes of the GO film, because of the strong interactions between the excited backward propagating cladding modes and the GO film. By detecting the transmission intensity changes of the cladding mode resonant dips at the wavelength of 1557 nm, the maximum sensitivity of 0.129 dB/%RH with a linear correlation coefficient of 99% under the RH range of 10-80% was obtained. The Bragg mode of TFBG can be used as power or wavelength references, since it is inherently insensitive to RH changes. In addition, the proposed humidity sensor shows a good performance in repeatability and stability.

  11. Effect of fiber reinforcement on thermo-oxidative stability and mechanical properties of polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Bowles, K. J.

    1992-01-01

    A number of studies have investigated the thermooxidative behavior of polymer matrix composites. Two significant observations have been made from these research efforts: (1) fiber reinforcement has a significant effect on composite thermal stability; and (2) geometric effects must be considered when evaluating thermal aging data. The polyimide PMR-15 was the matrix material used in these studies. The control composite material was reinforced with Celion 6000 graphite fiber. T-4OR graphite fibers, along with some very stable ceramic fibers were selected as reinforcing fibers because of their high thermal stability. The ceramic fibers were Nicalon (silicon carbide) and Nextel 312 (alumina-silica-boron oxide). The mechanical properties of the two graphite fiber composites were significantly different, probably owing to variations in interfacial bonding between the fibers and the polyimide matrix. Three oxidation mechanisms were observed: (1) the preferential oxidation of the Celion 6000 fiber ends at cut surfaces, leaving a surface of matrix material with holes where the fiber ends were originally situated; (2) preferential oxidation of the composite matrix; and (3) interfacial degradation by oxidation. The latter two mechanisms were also observed on fiber end cut surfaces. The fiber and interface attacks appeared to initiate interfiber cracking along these surfaces.

  12. Oxidation of carbon fiber surfaces for use as reinforcement in high-temperature cementitious material systems

    DOEpatents

    Sugama, Toshifumi.

    1990-05-22

    The interfacial bond characteristics between carbon fiber and a cement matrix, in high temperature fiber-reinforced cementitious composite systems, can be improved by the oxidative treatment of the fiber surfaces. Compositions and the process for producing the compositions are disclosed. 2 figs.

  13. Oxidation of carbon fiber surfaces for use as reinforcement in high-temperature cementitious material systems

    DOEpatents

    Sugama, Toshifumi

    1990-01-01

    The interfacial bond characteristics between carbon fiber and a cement matrix, in high temperature fiber-reinforced cementitious composite systems, can be improved by the oxidative treatment of the fiber surfaces. Compositions and the process for producing the compositions are disclosed.

  14. A Comparative Study of Natural Fiber and Glass Fiber Fabrics Properties with Metal or Oxide Coatings

    NASA Astrophysics Data System (ADS)

    Lusis, Andrej; Pentjuss, Evalds; Bajars, Gunars; Sidorovicha, Uljana; Strazds, Guntis

    2015-03-01

    Rapidly growing global demand for technical textiles industries is stimulated to develop new materials based on hybrid materials (yarns, fabrics) made from natural and glass fibres. The influence of moisture on the electrical properties of metal and metal oxide coated bast (flax, hemp) fibre and glass fibre fabrics are studied by electrical impedance spectroscopy and thermogravimetry. The bast fibre and glass fiber fabrics are characterized with electrical sheet resistance. The method for description of electrical sheet resistance of the metal and metal oxide coated technical textile is discussed. The method can be used by designers to estimate the influence of moisture on technical data of new metal coated hybrid technical textile materials and products.

  15. Combining Untargeted and Targeted Proteomic Strategies for Discrimination and Quantification of Cashmere Fibers

    PubMed Central

    Li, Shanshan; Zhang, Yong; Wang, Jihua; Yang, Yunfei; Miao, Chen; Guo, Yufeng; Zhang, Zhidan; Cao, Qichen; Shui, Wenqing

    2016-01-01

    Cashmere is regarded as a specialty and luxury fiber due to its scarcity and high economic value. For fiber quality assessment, it is technically very challenging to distinguish and quantify the cashmere fiber from yak or wool fibers because of their highly similar physical appearance and substantial protein sequence homology. To address this issue, we propose a workflow combining untargeted and targeted proteomics strategies for selecting, verifying and quantifying biomarkers for cashmere textile authentication. Untargeted proteomic surveys were first applied to identify 174, 157, and 156 proteins from cashmere, wool and yak fibers, respectively. After marker selection at different levels, peptides turned out to afford much higher selectivity than proteins for fiber species discrimination. Subsequently, parallel reaction monitoring (PRM) methods were developed for ten selected peptide markers. The PRM-based targeted analysis of peptide markers enabled accurate determination of fiber species and cashmere percentages in different fiber mixtures. Furthermore, collective use of these peptide makers allowed us to discriminate and quantify cashmere fibers in commercial finished fabrics that have undergone heavy chemical treatments. Cashmere proportion measurement in fabric samples using our proteomic approach was in good agreement with results from traditional light microscopy, yet our method can be more readily standardized to become an objective and robust assay for assessing authenticity of fibers and textiles. We anticipate that the proteomic strategies presented in our study could be further implicated in discovery of quality trait markers for other products containing highly homologous proteomes. PMID:26789629

  16. Combining Untargeted and Targeted Proteomic Strategies for Discrimination and Quantification of Cashmere Fibers.

    PubMed

    Li, Shanshan; Zhang, Yong; Wang, Jihua; Yang, Yunfei; Miao, Chen; Guo, Yufeng; Zhang, Zhidan; Cao, Qichen; Shui, Wenqing

    2016-01-01

    Cashmere is regarded as a specialty and luxury fiber due to its scarcity and high economic value. For fiber quality assessment, it is technically very challenging to distinguish and quantify the cashmere fiber from yak or wool fibers because of their highly similar physical appearance and substantial protein sequence homology. To address this issue, we propose a workflow combining untargeted and targeted proteomics strategies for selecting, verifying and quantifying biomarkers for cashmere textile authentication. Untargeted proteomic surveys were first applied to identify 174, 157, and 156 proteins from cashmere, wool and yak fibers, respectively. After marker selection at different levels, peptides turned out to afford much higher selectivity than proteins for fiber species discrimination. Subsequently, parallel reaction monitoring (PRM) methods were developed for ten selected peptide markers. The PRM-based targeted analysis of peptide markers enabled accurate determination of fiber species and cashmere percentages in different fiber mixtures. Furthermore, collective use of these peptide makers allowed us to discriminate and quantify cashmere fibers in commercial finished fabrics that have undergone heavy chemical treatments. Cashmere proportion measurement in fabric samples using our proteomic approach was in good agreement with results from traditional light microscopy, yet our method can be more readily standardized to become an objective and robust assay for assessing authenticity of fibers and textiles. We anticipate that the proteomic strategies presented in our study could be further implicated in discovery of quality trait markers for other products containing highly homologous proteomes. PMID:26789629

  17. Delivery of Erbium:YAG laser radiation through side-firing germanium oxide optical fibers

    NASA Astrophysics Data System (ADS)

    Ngo, Anthony K.; Fried, Nathaniel M.

    2006-02-01

    The Erbium:YAG laser is currently being tested experimentally for endoscopic applications in urology, including more efficient laser lithotripsy and more precise incision of urethral strictures than the Holmium:YAG laser. While side-firing silica fibers are available for use with the Ho:YAG laser in urology, no such fibers exist for use with the Er:YAG laser. These applications may benefit from the availability of a side-firing, mid-infrared optical fiber capable of delivering the laser radiation at a 90-degree angle to the tissue. The objective of this study is to describe the simple construction and characterization of a side-firing germanium oxide fiber for potential use in endoscopic laser surgery. Side-firing fibers were constructed from 450-micron-core germanium oxide fibers of 1.45-m-length by polishing the distal tip at a 45-degree angle and placing a 1-cm-long protective quartz cap over the fiber tip. Er:YAG laser radiation with a wavelength of 2.94 microns, pulse duration of 300 microseconds, pulse repetition rate of 3 Hz, and pulse energies of from 5 to 550 mJ was coupled into the fibers. The fiber transmission rate and damage threshold measured 48 +/- 4 % and 149 +/- 37 mJ, respectively (n = 6 fibers). By comparison, fiber transmission through normal germanium oxide trunk fibers measured 66 +/- 3 %, with no observed damage (n = 5 fibers). Sufficient pulse energies were transmitted through the side-firing fibers for contact tissue ablation. Although these initial tests are promising, further studies will need to be conducted, focusing on assembly of more flexible, smaller diameter fibers, fiber bending transmission tests, long-term fiber reliability tests, and improvement of the fiber output spatial beam profile.

  18. The role of nitric oxide in muscle fibers with oxidative phosphorylation defects

    SciTech Connect

    Tengan, Celia H. . E-mail: chtengan@neuro.epm.br; Kiyomoto, Beatriz H.; Godinho, Rosely O.; Gamba, Juliana; Neves, Afonso C.; Schmidt, Beny; Oliveira, Acary S.B.; Gabbai, Alberto A.

    2007-08-03

    NO has been pointed as an important player in the control of mitochondrial respiration, especially because of its inhibitory effect on cytochrome c oxidase (COX). However, all the events involved in this control are still not completely elucidated. We demonstrate compartmentalized abnormalities on nitric oxide synthase (NOS) activity on muscle biopsies of patients with mitochondrial diseases. NOS activity was reduced in the sarcoplasmic compartment in COX deficient fibers, whereas increased activity was found in the sarcolemma of fibers with mitochondrial proliferation. We observed increased expression of neuronal NOS (nNOS) in patients and a correlation between nNOS expression and mitochondrial content. Treatment of skeletal muscle culture with an NO donor induced an increase in mitochondrial content. Our results indicate specific roles of NO in compensatory mechanisms of muscle fibers with mitochondrial deficiency and suggest the participation of nNOS in the signaling process of mitochondrial proliferation in human skeletal muscle.

  19. RADIATION-RESISTANT FIBER OPTIC STRAIN SENSORS FOR SNS TARGET INSTRUMENTATION

    SciTech Connect

    Blokland, Willem; Bryan, Jeff; Riemer, Bernie; Sangrey, Robert L; Wendel, Mark W; Liu, Yun

    2016-01-01

    Measurement of stresses and strains in the mercury tar-get vessel of the Spallation Neutron Source (SNS) is important to understand the structural dynamics of the target. This work reports the development of radiation-resistant fiber optic strain sensors for the SNS target in-strumentation.

  20. Thermo-oxidative stability studies of PMR-15 polymer matrix composites reinforced with various fibers

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.

    1990-01-01

    An experimental study was conducted to measure the thermo-oxidative stability of PMR-15 polymer matrix composites reinforced with various fibers and to observe differences in the way they degrade in air. The fibers that were studied included graphite and the thermally stable Nicalon and Nextel ceramic fibers. Weight loss rates for the different composites were assessed as a function of mechanical properties, specimen geometry, fiber sizing, and interfacial bond strength. Differences were observed in rates of weight loss, matrix cracking, geometry dependency, and fiber-sizing effects. It was shown that Celion 6000 fiber-reinforced composites do not exhibit a straight-line Arrhenius relationship at temperatures above 316 C.

  1. Electrical and optical characterization of copper oxide/calcium oxide nanocomposite fibers.

    PubMed

    Vijayakumar, G Nixon Samuel

    2014-04-01

    The Poly(vinyl alcohol)/copper acetate/calcium acetate sol was prepared by sol-gel route. Poly(vinyl alcohol)/copper acetate/calcium acetate composite nanofibers were synthesized by electrospinning process. These nanofibers had an average diameter of 200 nm. Calcining these fibers at 1000 degrees C produced copper oxide/calcium oxide nanofibers with average diameter of 75 nm. These fibers were characterized by Atomic Force Microscopy, Scanning Electron Microscopy, Fourier Transform Infrared spectroscopy, powder X-ray Diffraction, Ultraviolet spectroscopy, dielectric study and Second Harmonic Generation (SHG) efficiency test. Band gap energy was calculated as 4.1 eV. SHG efficiency was found to be 1.7 times than that of KDP. PMID:24734744

  2. Helical graphene oxide fibers as a stretchable sensor and an electrocapillary sucker.

    PubMed

    Hua, Chunfei; Shang, Yuanyuan; Li, Xiying; Hu, Xiaoyang; Wang, Ying; Wang, Xinchang; Zhang, Yingjiu; Li, Xinjian; Duan, Huiling; Cao, Anyuan

    2016-05-19

    Fibers made from carbon nanotubes or graphene are strong and conductive; encoding helical structures into these fibers may render useful properties such as high stretchability. Here, we directly spin freestanding graphene oxide (GO) films into helical fibers consisting of uniformly arranged loops with tunable diameters, under controlled environmental humidity. Reduced GO fibers with a helical shape are stretched elastically with a reversible electrical resistance change for many strain cycles. Stretchable temperature sensors built on helical fibers work at large strains (up to 50%) and high temperature (up to 300 °C), with a reliable deformation-independent response. The GO fibers also contain through-channels inside with suitable pore size, which can take up an aqueous electrolyte quickly under a low bias, resulting in a fiber-shaped, on-off switchable electrocapillary sucker. Our multifunctional helical and hollow GO fibers have potential applications in stretchable fiber-shaped sensors, actuators and nano-fluid systems. PMID:27147483

  3. A scintillating fiber-optic active target (SFT) for studies of high energy photoproduction

    SciTech Connect

    Ruchti, R.; Baumbaugh, B.; Bishop, J.; Busenitz, J.; Cason, N.; Cunningham, J.; Gardner, R.; Kennedy, C.; Mannel, E.; Mountain, R.J.

    1987-10-01

    A high resolution, gateable, Scintillating Fiber Target (SFT) has been developed for Fermilab Experiment E687 to study charm and beauty particle production and decay in high energy photon interactions. The detector consists of a scintillating target of either GS1 Cerium glass fibers or polystyrene fibers of 29..mu..m cross section, a multi-stage image intensifier and an intensified CCD or SIT/VIDICON camera system used in conjunction with a custom-built video data acquisition system. 7 refs., 8 figs., 1 tab.

  4. Helical graphene oxide fibers as a stretchable sensor and an electrocapillary sucker

    NASA Astrophysics Data System (ADS)

    Hua, Chunfei; Shang, Yuanyuan; Li, Xiying; Hu, Xiaoyang; Wang, Ying; Wang, Xinchang; Zhang, Yingjiu; Li, Xinjian; Duan, Huiling; Cao, Anyuan

    2016-05-01

    Fibers made from carbon nanotubes or graphene are strong and conductive; encoding helical structures into these fibers may render useful properties such as high stretchability. Here, we directly spin freestanding graphene oxide (GO) films into helical fibers consisting of uniformly arranged loops with tunable diameters, under controlled environmental humidity. Reduced GO fibers with a helical shape are stretched elastically with a reversible electrical resistance change for many strain cycles. Stretchable temperature sensors built on helical fibers work at large strains (up to 50%) and high temperature (up to 300 °C), with a reliable deformation-independent response. The GO fibers also contain through-channels inside with suitable pore size, which can take up an aqueous electrolyte quickly under a low bias, resulting in a fiber-shaped, on-off switchable electrocapillary sucker. Our multifunctional helical and hollow GO fibers have potential applications in stretchable fiber-shaped sensors, actuators and nano-fluid systems.Fibers made from carbon nanotubes or graphene are strong and conductive; encoding helical structures into these fibers may render useful properties such as high stretchability. Here, we directly spin freestanding graphene oxide (GO) films into helical fibers consisting of uniformly arranged loops with tunable diameters, under controlled environmental humidity. Reduced GO fibers with a helical shape are stretched elastically with a reversible electrical resistance change for many strain cycles. Stretchable temperature sensors built on helical fibers work at large strains (up to 50%) and high temperature (up to 300 °C), with a reliable deformation-independent response. The GO fibers also contain through-channels inside with suitable pore size, which can take up an aqueous electrolyte quickly under a low bias, resulting in a fiber-shaped, on-off switchable electrocapillary sucker. Our multifunctional helical and hollow GO fibers have potential

  5. Cellulose nanowhiskers extracted from TEMPO-oxidized jute fibers.

    PubMed

    Cao, Xinwang; Ding, Bin; Yu, Jianyong; Al-Deyab, Salem S

    2012-10-01

    Cellulose nanowhiskers is a kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Here, for the first time, a novel controllable fabrication of cellulose nanowhiskers from jute fibers with a high yield (over 80%) via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization is reported. The versatile jute cellulose nanowhiskers with ultrathin diameters (3-10 nm) and high crystallinity (69.72%), contains C6 carboxylate groups converted from C6 primary hydroxyls, which would be particularly useful for applications in the nanocomposites as reinforcing phase, as well as in tissue engineering, pharmaceutical and optical industries as additives. PMID:22840042

  6. The Regulation of Corticofugal Fiber Targeting by Retinal Inputs

    PubMed Central

    Grant, Eleanor; Hoerder-Suabedissen, Anna; Molnár, Zoltán

    2016-01-01

    Corticothalamic projection systems arise from 2 main cortical layers. Layer V neurons project exclusively to higher-order thalamic nuclei, while layer VIa fibers project to both first-order and higher-order thalamic nuclei. During early postnatal development, layer VIa and VIb fibers accumulate at the borders of the dorsal lateral geniculate nucleus (dLGN) before they innervate it. After neonatal monocular enucleation or silencing of the early retinal activity, there is premature entry of layer VIa and VIb fibers into the dLGN contralateral to the manipulation. Layer V fibers do not innervate the superficial gray layer of the superior colliculus during the first postnatal week, but also demonstrate premature entry to the contralateral superficial gray layer following neonatal enucleation. Normally, layer V driver projections to the thalamus only innervate higher-order nuclei. Our results demonstrate that removal of retinal input from the dLGN induces cortical layer V projections to aberrantly enter, arborize, and synapse within the first-order dLGN. These results suggest that there is cross-hierarchical corticothalamic plasticity after monocular enucleation. Cross-hierarchical rewiring has been previously demonstrated in the thalamocortical system (Pouchelon et al. 2014), and now we provide evidence for cross-hierarchical corticothalamic rewiring after loss of the peripheral sensory input. PMID:26744542

  7. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

    NASA Astrophysics Data System (ADS)

    Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

    2016-03-01

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response

  8. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

    PubMed Central

    Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

    2016-01-01

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response PMID:27010752

  9. Interfacial microstructure and properties of carbon fiber composites modified with graphene oxide.

    PubMed

    Zhang, Xiaoqing; Fan, Xinyu; Yan, Chun; Li, Hongzhou; Zhu, Yingdan; Li, Xiaotuo; Yu, Liping

    2012-03-01

    The performance of carbon fiber-reinforced composites is dependent to a great extent on the properties of fiber-matrix interface. To improve the interfacial properties in carbon fiber/epoxy composites, we directly introduced graphene oxide (GO) sheets dispersed in the fiber sizing onto the surface of individual carbon fibers. The applied graphite oxide, which could be exfoliated to single-layer GO sheets, was verified by atomic force microscope (AFM). The surface topography of modified carbon fibers and the distribution of GO sheets in the interfacial region of carbon fibers were detected by scanning electron microscopy (SEM). The interfacial properties between carbon fiber and matrix were investigated by microbond test and three-point short beam shear test. The tensile properties of unidirectional (UD) composites were investigated in accordance with ASTM standards. The results of the tests reveal an improved interfacial and tensile properties in GO-modified carbon fiber composites. Furthermore, significant enhancement of interfacial shear strength (IFSS), interlaminar shear strength (ILSS), and tensile properties was achieved in the composites when only 5 wt % of GO sheets introduced in the fiber sizing. This means that an alternative method for improving the interfacial and tensile properties of carbon fiber composites by controlling the fiber-matrix interface was developed. Such multiscale reinforced composites show great potential with their improved mechanical performance to be likely applied in the aerospace and automotive industries. PMID:22391332

  10. FETs Based on Doped Polyaniline/Polyethylene Oxide Fibers

    NASA Technical Reports Server (NTRS)

    Theofylaktos, Noulie; Robinson, Daryl; Miranda, Felix; Pinto, Nicholas; Johnson, Alan, Jr.; MacDiarmid, Alan; Mueller, Carl

    2006-01-01

    A family of experimental highly miniaturized field-effect transistors (FETs) is based on exploitation of the electrical properties of nanofibers of polyaniline/ polyethylene oxide (PANi/PEO) doped with camphorsulfonic acid. These polymer-based FETs have the potential for becoming building blocks of relatively inexpensive, low-voltage, highspeed logic circuits that could supplant complementary metal oxide/semiconductor (CMOS) logic circuits. The development of these polymerbased FETs offers advantages over the competing development of FETs based on carbon nanotubes. Whereas it is difficult to control the molecular structures and, hence, the electrical properties of carbon nanotubes, it is easy to tailor the electrical properties of these polymerbased FETs, throughout the range from insulating through semiconducting to metallic, through choices of doping levels and chemical manipulation of polymer side chains. A further advantage of doped PANi/PEO nanofibers is that they can be made to draw very small currents and operate at low voltage levels, and thus are promising for applications in which there are requirements to use many FETs to obtain large computational capabilities while minimizing power demands. Fabrication of an experimental FET in this family begins with the preparation of a substrate as follows: A layer of silicon dioxide between 50 and 200 nm thick is deposited on a highly doped (resistivity 0.01 W.cm) silicon substrate, then gold electrodes/contact stripes are deposited on the oxide. Next, one or more fibers of camphorsulphonic acid-doped PANi/PEO having diameters of the order of 100 nm are electrospun onto the substrate so as to span the gap between the gold electrodes (see Figure 1). Figure 2 depicts measured current-versus-voltage characteristics of the device of Figure 1, showing that saturation channel currents occur at source-todrain potentials that are surprisingly low, relative to those of CMOS FETs. The hole mobility in the depletion regime in

  11. Oxidation Kinetics and Strength Degradation of Carbon Fibers in a Cracked Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.

    2003-01-01

    Experimental results and oxidation modeling will be presented to discuss carbon fiber susceptibility to oxidation, the oxidation kinetics regimes and composite strength degradation and failure due to oxidation. Thermogravimetric Analysis (TGA) was used to study the oxidation rates of carbon fiber and of a pyro-carbon interphase. The analysis was used to separately obtain activation energies for the carbon constituents within a C/SiC composite. TGA was also conducted on C/SiC composite material to study carbon oxidation and crack closure as a function of temperature. In order to more closely match applications conditions C/SiC tensile coupons were also tested under stressed oxidation conditions. The stressed oxidation tests show that C/SiC is much more susceptible to oxidation when the material is under an applied load where the cracks are open and allow for oxygen ingress. The results help correlate carbon oxidation with composite strength reduction and failure.

  12. Dissolution of Neptunium Oxide in Unirradiated Mark 53 Targets

    SciTech Connect

    Rudisill, T.S.

    2002-06-07

    Nine unirradiated Mark 53 targets currently stored at the K-Reactor must be dissolved to allow recovery of the neptunium content. The Mark 53 targets are an aluminum clad neptunium oxide (NpO2)/aluminum metal cermet used for the production of plutonium-238. The targets will be dissolved in H-Canyon and blended with solutions generated from routine fuel dissolutions for purification by solvent extraction

  13. Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor

    NASA Technical Reports Server (NTRS)

    Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

    2001-01-01

    A process for producing polycrystalline silicon carbide by heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

  14. Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor

    NASA Technical Reports Server (NTRS)

    Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

    2000-01-01

    A process for producing polycrystalline silicon carbide includes heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

  15. Demonstration of nitric oxide on asbestos and silicon carbide fibers with a new ultraviolet spectrophotometric assay.

    PubMed Central

    Leanderson, P; Lagesson, V; Tagesson, C

    1997-01-01

    Nitric oxide (NO) has a number of important functions in biological systems and may play a role in the toxicity of mineral fibers. We investigated whether NO might be present on the surface of mineral fibers and if crocidolite could adsorb NO from NO gas or cigarette smoke. NO was determined with a new gas chromatography-ultraviolet spectrophotometric technique after thermal desorption from the fiber surface and injection in a gas flow cell. NO was found in different amounts on chrysotile B, crocidolite, amosite, and silicon carbide whiskers. There was a strong correlation between the amount of NO and the specific surface area of these fibers (r = 0.98). NO could not be demonstrated on rockwool fibers [man-made vitreous fiber(s) (MMVF)21 and MMVF22] or silicon nitride whiskers. NO on crocidolite, amosite, and silicon carbide whiskers was readily desorbed from the fibers at increased temperature, while NO on chrysotile B seemed to be more firmly adsorbed to the fiber and required a longer period of time to be desorbed. The amount of NO bound to crocidolite increased from 34 micrograms/g fiber to 85 and 474 micrograms/g after exposing the fibers to cigarette smoke and NO gas, respectively. These findings indicate that a) NO adsorbs to fiber surfaces, b) some fibers adsorb more NO than others, c) some fibers adsorb NO more strongly than others, and d) the amounts of NO on fibers may be increased after exposure of the fiber to cigarette smoke or other sources of NO. The biological significance of NO on mineral fibers remains to be investigated. Images Figure 3. PMID:9400696

  16. Encapsulation of T4 bacteriophage in electrospun poly(ethylene oxide)/cellulose diacetate fibers.

    PubMed

    Korehei, Reza; Kadla, John F

    2014-01-16

    Phage therapy is a potentially beneficial approach to food preservation and storage. Sustained delivery of bacteriophage can prevent bacterial growth on contaminated food surfaces. Using coaxial electrospinning bacteriophage can be encapsulated in electrospun fibers with high viability. The resulting bio-based electrospun fibers may have potential as a food packaging material. In the present work, T4 bacteriophage (T4 phage) was incorporated into core/shell electrospun fibers made from poly(ethylene oxide) (PEO), cellulose diacetate (CDA), and their blends. Fibers prepared using PEO as the shell polymer showed an immediate burst release of T4 phage upon submersion in buffer. The blending of CDA with PEO significantly decreased the rate of phage release, with no released T4 phage being detected from the solely CDA fibers. Increasing the PEO molecular weight increased the electrospun fiber diameter and viscosity of the releasing medium, which resulted in a relatively slower T4 phage release profile. SEM analyses of the electrospun fiber morphologies were in good agreement with the T4 phage release profiles. Depending on the PEO/CDA ratio, the post-release electrospun fiber morphologies varied from discontinuous fibers to minimally swollen fibers. From these results it is suggested that the T4 phage release mechanism is through solvent activation/polymer dissolution in the case of the PEO fibers and/or by diffusion control from the PEO/CDA blend fibers. PMID:24188849

  17. Relative sliding durability of two candidate high temperature oxide fiber seal materials

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Steinetz, Bruce M.

    1991-01-01

    A test program to determine the relative sliding durability of two candidate ceramic fibers for high temperature sliding seal applications is described. Pin on disk tests were used to evaluate potential seal materials. Friction during the tests and fiber wear, indicated by the extent of fibers broken in a test bundle or yarn, was measured at the end of a test. In general, friction and wear increase with test temperature. This may be due to a reduction in fiber strength, a change in the surface chemistry at the fiber/counterface interface due to oxidation, adsorption and/or desorption of surface species and, to a lesser extent, an increase in counterface surface roughness due to oxidation at elevated temperatures. The relative fiber durability correlates with tensile strength indicating that tensile data, which is more readily available than sliding durability data, may be useful in predicting fiber wear behavior under various conditions. A simple model developed using dimensional analysis shows that the fiber durability is related to a dimensionless parameter which represents the ratio of the fiber strength to the fiber stresses imposed by sliding.

  18. Electrospun Contrast-Agent-Loaded Fibers for Colon-Targeted MRI.

    PubMed

    Jin, Miao; Yu, Deng-Guang; Wang, Xia; Geraldes, Carlos F G C; Williams, Gareth R; Bligh, S W Annie

    2016-04-01

    Magnetic resonance imaging is a diagnostic tool used for detecting abnormal organs and tissues, often using Gd(III) complexes as contrast-enhancing agents. In this work, core-shell polymer fibers have been prepared using coaxial electrospinning, with the intent of delivering gadolinium (III) diethylenetriaminepentaacetate hydrate (Gd(DTPA)) selectively to the colon. The fibers comprise a poly(ethylene oxide) (PEO) core loaded with Gd(DTPA), and a Eudragit S100 shell. They are homogeneous, with distinct core-shell phases. The components in the fibers are dispersed in an amorphous fashion. The proton relaxivities of Gd(DTPA) are preserved after electrospinning. To permit easy visualization of the release of the active ingredient from the fibers, analogous materials are prepared loaded with the dye rhodamine B. Very little release is seen in a pH 1.0 buffer, while sustained release is seen at pH 7.4. The fibers thus have the potential to selectively deliver Gd(DTPA) to the colon. Mucoadhesion studies reveal there are strong adhesive forces between porcine colon mucosa and PEO from the core, and the dye-loaded fibers can be successfully used to image the porcine colon wall. The electrospun core-shell fibers prepared in this work can thus be developed as advanced functional materials for effective imaging of colonic abnormalities. PMID:26899401

  19. Zinc Oxide Nanowire Interphase for Enhanced Lightweight Polymer Fiber Composites

    NASA Technical Reports Server (NTRS)

    Sodano, Henry A.; Brett, Robert

    2011-01-01

    The objective of this work was to increase the interfacial strength between aramid fiber and epoxy matrix. This was achieved by functionalizing the aramid fiber followed by growth of a layer of ZnO nanowires on the fiber surface such that when embedded into the polymer, the load transfer and bonding area could be substantially enhanced. The functionalization procedure developed here created functional carboxylic acid surface groups that chemically interact with the ZnO and thus greatly enhance the strength of the interface between the fiber and the ZnO.

  20. Adhesion enhancement of indium tin oxide (ITO) coated quartz optical fibers

    NASA Astrophysics Data System (ADS)

    Wang, Yihua; Liu, Jing; Wu, Xu; Yang, Bin

    2014-07-01

    Transparent conductive indium tin oxide (ITO) film was prepared on optical fiber through a multi-step sol-gel process. The influence of annealing temperature on the adhesion of ITO coated optical fibers was studied. Different surface treatments were applied to improve the adhesion between ITO film and quartz optical fiber. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD), UV-vis spectrophotometer and Avometer were used to characterize the morphology, crystal structure and photo-electric properties. A thermal shock test was used to evaluate the adhesion. The result shows that the adhesion between ITO film and quartz optical fiber can be strongly influenced by the annealing process, and optimal adhesion can be acquired when annealing temperature is 500 °C. Surface treatments of ultrasonic cleaning and the application of surface-active agent have effectively enhanced the adhesion and photo-electric properties of indium tin oxide film coated quartz optical fiber.

  1. Effect of plasma etching on destructive adsorption properties of polypropylene fibers containing magnesium oxide nanoparticles.

    PubMed

    Lange, Laura E; Obendorf, S Kay

    2012-02-01

    Dermal absorption of pesticides poses a danger for agricultural workers. Use of personal protection equipment (PPE) is required to provide protection; some of the current PPE involves impermeable barriers. In these barrier materials, the same mechanism that prevents the penetration of toxic chemicals also blocks the passage of water vapor and air from flowing through the material, making the garments uncomfortable. Fibers that degrade organophosphate pesticides, such as methyl parathion, were developed by incorporating metal oxides. These modified fibers can be incorporated into conventional fabric structures that allow water vapor to pass through, thereby maintaining comfort. Fibers with self-decontamination functionality were developed by incorporating magnesium oxide (MgO) nanoparticles into a polypropylene (PP) melt-extruded fiber. These fibers were then treated with plasma etching to expose increased surface area of the MgO nanoparticles. Three steps were involved in this research project: (1) determining the reactivity of MgO and methyl parathion, (2) making melt-spun MgO/PP fibers, and (3) testing the reactivity of MgO/PP composite fibers and methyl parathion. It was confirmed that MgO stoichiometrically degrades methyl parathion by way of destructive adsorption. The etching of the PP fibers containing MgO nanoparticles increased the chemical accessibility of MgO reactive sites, therefore making them more effective in degrading methyl parathion. These fibers can enhance the protection provided by PPE to agricultural and horticultural workers and military personnel. PMID:21850511

  2. Effects of Graphene Oxide Modified Sizing Agents on Interfacial Properties of Carbon Fibers/Epoxy Composites.

    PubMed

    Zhang, Qingbo; Jiang, Dawei; Liu, Li; Huang, Yudong; Long, Jun; Wu, Guangshun; Wu, Zijian; Umar, Ahmad; Guo, Jiang; Zhang, Xi; Guo, Zhanhu

    2015-12-01

    A kind of graphene oxide (GO) modified sizing agent was used to improve the interfacial properties of carbon fibers/epoxy composites. The surface topography of carbon fibers was investigated by scanning electron microscopy (SEM). The surface compositions of carbon fibers were determined by X-ray photoelectron spectroscopy (XPS) and the interfacial properties of composites were studied by interlaminar shear strength (ILSS). The results show that the existence of GO increases the content of reactive functional groups on carbon fiber surface. Thus it enhances the interfacial properties of carbon fibers/epoxy composites. When GO loading in sizing agents is 1 wt%, the ILSS value of composite reaches to 96.2 MPa, which is increased by 27.2% while comparing with unsized carbon fiber composites. Furthermore, the ILSS of composites after aging is also increased significantly with GO modified sizing agents. PMID:26682416

  3. Studies on non-oxide coating on carbon fibers using plasma enhanced chemical vapor deposition technique

    NASA Astrophysics Data System (ADS)

    Patel, R. H.; Sharma, S.; Prajapati, K. K.; Vyas, M. M.; Batra, N. M.

    2016-05-01

    A new way of improving the oxidative behavior of carbon fibers coated with SiC through Plasma Enhanced Chemical Vapor Deposition technique. The complete study includes coating of SiC on glass slab and Stainless steel specimen as a starting test subjects but the major focus was to increase the oxidation temperature of carbon fibers by PECVD technique. This method uses relatively lower substrate temperature and guarantees better stoichiometry than other coating methods and hence the substrate shows higher resistance towards mechanical and thermal stresses along with increase in oxidation temperature.

  4. Application of diffusion barriers to the refractory fibers of tungsten, columbium, carbon and aluminum oxide

    NASA Technical Reports Server (NTRS)

    Douglas, F. C.; Paradis, E. L.; Veltri, R. D.

    1973-01-01

    A radio frequency powered ion-plating system was used to plate protective layers of refractory oxides and carbide onto high strength fiber substrates. Subsequent overplating of these combinations with nickel and titanium was made to determine the effectiveness of such barrier layers in preventing diffusion of the overcoat metal into the fibers with consequent loss of fiber strength. Four substrates, five coatings, and two metal matrix materials were employed for a total of forty material combinations. The substrates were tungsten, niobium, NASA-Hough carbon, and Tyco sapphire. The diffusion-barrier coatings were aluminum oxide, yttrium oxide, titanium carbide, tungsten carbide with 14% cobalt addition, and zirconium carbide. The metal matrix materials were IN 600 nickel and Ti 6/4 titanium. Adhesion of the coatings to all substrates was good except for the NASA-Hough carbon, where flaking off of the oxide coatings in particular was observed.

  5. Fiber

    MedlinePlus

    ... it can help with weight control. Fiber aids digestion and helps prevent constipation . It is sometimes used ... fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in ...

  6. Oxide Fiber Cathode Materials for Rechargeable Lithium Cells

    NASA Technical Reports Server (NTRS)

    Rice, Catherine E.; Welker, Mark F.

    2008-01-01

    LiCoO2 and LiNiO2 fibers have been investigated as alternatives to LiCoO2 and LiNiO2 powders used as lithium-intercalation compounds in cathodes of rechargeable lithium-ion electrochemical cells. In making such a cathode, LiCoO2 or LiNiO2 powder is mixed with a binder [e.g., poly(vinylidene fluoride)] and an electrically conductive additive (usually carbon) and the mixture is pressed to form a disk. The binder and conductive additive contribute weight and volume, reducing the specific energy and energy density, respectively. In contrast, LiCoO2 or LiNiO2 fibers can be pressed and sintered to form a cathode, without need for a binder or a conductive additive. The inter-grain contacts of the fibers are stronger and have fewer defects than do those of powder particles. These characteristics translate to increased flexibility and greater resilience on cycling and, consequently, to reduced loss of capacity from cycle to cycle. Moreover, in comparison with a powder-based cathode, a fiber-based cathode is expected to exhibit significantly greater ionic and electronic conduction along the axes of the fibers. Results of preliminary charge/discharge-cycling tests suggest that energy densities of LiCoO2- and LiNiO2-fiber cathodes are approximately double those of the corresponding powder-based cathodes.

  7. A novel structure photonic crystal fiber based on bismuth-oxide for optical parametric amplification

    NASA Astrophysics Data System (ADS)

    Jin, Cang; Yuan, Jinhui; Yu, Chongxiu

    2010-11-01

    The heavy metal oxide glasses containing bismuth such as bismuth sesquioxide show unique high refractive index. In addition, the bismuth-oxide based glass does not include toxic elements such as Pb, As, Se, Te, and exhibits well chemical, mechanical and thermal stability. Hence, it is used to fabricate high nonlinear fiber for nonlinear optical application. Although the bismuth-oxide based high nonlinear fiber can be fusion-spliced to conventional silica fibers and have above advantages, yet it suffers from large group velocity dispersion because of material chromatic dispersion which restricts its utility. In regard to this, the micro-structure was introduced to adjust the dispersion of bismuth-oxide high nonlinear fiber in the 1550nm wave-band. In this paper, a hexagonal solid-core micro-structure is developed to balance its dispersion and nonlinearity. Our simulation and calculation results show that the bismuth-oxide based photonic crystal fiber has near zero dispersion around 1550nm where the optical parametric amplification suitable wavelength is. Its dispersion slop in the communication wavelength range is also relatively flat. Moreover, both nonlinear coefficient and model filed distribution were simulated, respectively.

  8. Oxidative Stress in Intracerebral Hemorrhage: Sources, Mechanisms, and Therapeutic Targets

    PubMed Central

    Hu, Xin; Tao, Chuanyuan; Gan, Qi; Zheng, Jun; Li, Hao; You, Chao

    2016-01-01

    Intracerebral hemorrhage (ICH) is associated with the highest mortality and morbidity despite only constituting approximately 10–15% of all strokes. Complex underlying mechanisms consisting of cytotoxic, excitotoxic, and inflammatory effects of intraparenchymal blood are responsible for its highly damaging effects. Oxidative stress (OS) also plays an important role in brain injury after ICH but attracts less attention than other factors. Increasing evidence has demonstrated that the metabolite axis of hemoglobin-heme-iron is the key contributor to oxidative brain damage after ICH, although other factors, such as neuroinflammation and prooxidases, are involved. This review will discuss the sources, possible molecular mechanisms, and potential therapeutic targets of OS in ICH. PMID:26843907

  9. Proposal of Liquid Cannon Target Driven by Fiber Laser for Micro-Thruster in Satellite

    NASA Astrophysics Data System (ADS)

    Yabe, Takashi; Ohzono, Hirokazu; Ohkubo, Tomomasa; Baasandash, Choijil; Yamaguchi, Masashi; Oku, Takehiro; Taniguchi, Kazumoto; Miyazaki, Sho; Akoh, Ryosuke; Ogata, Yoichi; Rosenberg, Benjamin; Yoshida, Minoru

    2004-03-01

    We propose a new concept controlling a satellite by a fiber laser loaded in it and demonstrated the acceleration of pendulum with 7kW/2n and 2kHz fiber laser, and measured the Cm of 16Ns/MJ corresponding to the scaling of YAG laser. This laser can be easily bundled to generate much larger power. For more efficient acceleration, we propose ``metal-free water cannon target'', the new concept of propulsion using only water. The momentum coupling coefficient of 2500[Ns/MJ] was achieved with vacuum pump oil instead of water, and we succeeded in controlling the driving direction by the system based on the new concept. This can be used for thrusting a satellite and controlling its posture in combination with fiber lasers.

  10. Proposal of Liquid Cannon Target Driven by Fiber Laser for Micro-Thruster in Satellite

    SciTech Connect

    Yabe, Takashi; Ohzono, Hirokazu; Ohkubo, Tomomasa; Baasandash, Choijil; Yamaguchi, Masashi; Oku, Takehiro; Taniguchi, Kazumoto; Miyazaki, Sho; Akoh, Ryosuke; Ogata, Yoichi; Rosenberg, Benjamin; Yoshida, Minoru

    2004-03-30

    We propose a new concept controlling a satellite by a fiber laser loaded in it and demonstrated the acceleration of pendulum with 7kW/2n and 2kHz fiber laser, and measured the Cm of 16Ns/MJ corresponding to the scaling of YAG laser. This laser can be easily bundled to generate much larger power. For more efficient acceleration, we propose 'metal-free water cannon target', the new concept of propulsion using only water. The momentum coupling coefficient of 2500[Ns/MJ] was achieved with vacuum pump oil instead of water, and we succeeded in controlling the driving direction by the system based on the new concept. This can be used for thrusting a satellite and controlling its posture in combination with fiber lasers.

  11. Carbon aerogel composites prepared by ambient drying and using oxidized polyacrylonitrile fibers as reinforcements.

    PubMed

    Feng, Junzong; Zhang, Changrui; Feng, Jian; Jiang, Yonggang; Zhao, Nan

    2011-12-01

    Carbon fiber-reinforced carbon aerogel composites (C/CAs) for thermal insulators were prepared by copyrolysis of resorcinol-formaldehyde (RF) aerogels reinforced by oxidized polyacrylonitrile (PAN) fiber felts. The RF aerogel composites were obtained by impregnating PAN fiber felts with RF sols, then aging, ethanol exchanging, and drying at ambient pressure. Upon carbonization, the PAN fibers shrink with the RF aerogels, thus reducing the difference of shrinkage rates between the fiber reinforcements and the aerogel matrices, and resulting in C/CAs without any obvious cracks. The three point bend strength of the C/CAs is 7.1 ± 1.7 MPa, and the thermal conductivity is 0.328 W m(-1) K(-1) at 300 °C in air. These composites can be used as high-temperature thermal insulators (in inert atmospheres or vacuum) or supports for phase change materials in thermal protection system. PMID:22047011

  12. Growth of sapphire and oxide eutectic fibers by the EFG technique

    NASA Astrophysics Data System (ADS)

    Kurlov, V. N.; Stryukov, D. O.; Shikunova, I. A.

    2016-01-01

    Single-crystal sapphire and oxide binary (Al2O3-Y3Al5O12, Al2O3-Er3Al5O12, Al2O3- GdAlO3) and ternary (Al2O3-ZrO2(Y2O3)) eutectic fibers of 150-300 µm in diameters were grown by the edge-defined film-fed growth (EFG) technique. Microstructure and some properties of fibers were investigated.

  13. Development of a core sheath process for production of oxide fibers

    NASA Technical Reports Server (NTRS)

    Freske, S.

    1972-01-01

    Improvements were sought in an oxide fiber of a core sheath configuration intended for structural applications at 2000 F (1093 C). Discontinuities in the core were eliminated by using core materials other than pure alumina, and continuous core sheath fibers were produced. In the case of some core materials, the continuous sections were sufficiently long for applications in short fiber composites. Creep at 2000 F (1093 C) was found to be due, in most cases, to breaks in the core, allowing the glass sheath to creep. Evidence was obtained indicating that a closer match between the thermal expansion coefficient of the sheath and the core would greatly improve the strength.

  14. Cell Labeling and Targeting with Superparamagnetic Iron Oxide Nanoparticles.

    PubMed

    Tefft, Brandon J; Uthamaraj, Susheil; Harburn, J Jonathan; Klabusay, Martin; Dragomir-Daescu, Dan; Sandhu, Gurpreet S

    2015-01-01

    Targeted delivery of cells and therapeutic agents would benefit a wide range of biomedical applications by concentrating the therapeutic effect at the target site while minimizing deleterious effects to off-target sites. Magnetic cell targeting is an efficient, safe, and straightforward delivery technique. Superparamagnetic iron oxide nanoparticles (SPION) are biodegradable, biocompatible, and can be endocytosed into cells to render them responsive to magnetic fields. The synthesis process involves creating magnetite (Fe3O4) nanoparticles followed by high-speed emulsification to form a poly(lactic-co-glycolic acid) (PLGA) coating. The PLGA-magnetite SPIONs are approximately 120 nm in diameter including the approximately 10 nm diameter magnetite core. When placed in culture medium, SPIONs are naturally endocytosed by cells and stored as small clusters within cytoplasmic endosomes. These particles impart sufficient magnetic mass to the cells to allow for targeting within magnetic fields. Numerous cell sorting and targeting applications are enabled by rendering various cell types responsive to magnetic fields. SPIONs have a variety of other biomedical applications as well including use as a medical imaging contrast agent, targeted drug or gene delivery, diagnostic assays, and generation of local hyperthermia for tumor therapy or tissue soldering. PMID:26554870

  15. Targeting Oxidative Stress in Central Nervous System Disorders.

    PubMed

    Patel, Manisha

    2016-09-01

    There is widespread recognition that reactive oxygen species (ROS) play key roles in normal brain function and pathology in the context of neurological disease. Oxidative stress continues to be a key therapeutic target for neurological diseases. In developing antioxidant therapies for neurological disease, special attention should be given to the brain's unique vulnerability to oxidative insults and its architecture. Consideration of antioxidant therapy should be guided by a strong rationale for oxidative stress in a given neurological disease. This review provides an overview of processes that can guide the development of antioxidant therapies in neurological diseases, such as knowledge of basic redox mechanisms, unique features of brain pathophysiology, mechanisms and classes of antioxidants, and desirable properties of drug candidates. PMID:27491897

  16. Carbon oxidation in ceramic composites and the evaluation of interfacial sealing for oxidation resistant fiber-reinforced composite systems

    NASA Astrophysics Data System (ADS)

    Glime, William Harrison, III

    1997-11-01

    Carbon offers desirable properties as a fiber-matrix interphase material in ceramic matrix composites (CMC's), but oxidation of carbon at temperatures above 500sp°C has limited its utility. In an effort to better understand the kinetics associated with carbon oxidation pertaining to CMC applications, the origin of non-planar morphologies observed in the reaction front of carbon fibers and interphases receding into a ceramic matrix in the temperature range of 700sp°C to 1000sp°C was analyzed. A numerical simulation based on the finite difference method is utilized to evaluate the parameters which govern the morphology of the receding carbon reaction front. The study indicates that the morphology of the reaction front contains information regarding the interplay between oxidation behavior and microstructural features of the carbon. Carbon oxidation was found to obey "weak-link" behavior, that is, a sub-component which is more susceptible to oxidation governs the recession kinetics. The implications of weak link oxidation to preservation of a carbon interphase in a ceramic composite are discussed. Interrupted interphases have demonstrated the ability to confine oxidation of a carbon interphase to a localized region adjacent to a matrix crack. Commercial SiC mono-filaments (SCS-6, Textron Specialty Materials) were modified with a laser to produce fibers with discontinuous carbon coatings that were used in experiments to study mechanical properties. The laser-scribed fibers were tested in isolation, used in single-fiber microcomposites, or incorporated into small bulk composite specimens using a powder processing route to produce the matrix. The mechanical performance of the various types of specimens prepared using the laser scribing technique is presented and these results are used in a simulation of ultimate composite properties. The effect of fiber matrix fusion, by direct bonding or through a reaction product which seals the interface, was investigated with

  17. Highly tunable interfacial adhesion of glass fiber by hybrid multilayers of graphene oxide and aramid nanofiber.

    PubMed

    Park, Byeongho; Lee, Wonoh; Lee, Eunhee; Min, Sa Hoon; Kim, Byeong-Su

    2015-02-11

    The performance of fiber-reinforced composites is governed not only by the nature of each individual component comprising the composite but also by the interfacial properties between the fiber and the matrix. We present a novel layer-by-layer (LbL) assembly for the surface modification of a glass fiber to enhance the interfacial properties between the glass fiber and the epoxy matrix. Solution-processable graphene oxide (GO) and an aramid nanofiber (ANF) were employed as active components for the LbL assembly onto the glass fiber, owing to their abundant functional groups and mechanical properties. We found that the interfacial properties of the glass fibers uniformly coated with GO and ANF multilayers, such as surface free energy and interfacial shear strength, were improved by 23.6% and 39.2%, respectively, compared with those of the bare glass fiber. In addition, the interfacial adhesion interactions between the glass fiber and the epoxy matrix were highly tunable simply by changing the composition and the architecture of layers, taking advantage of the versatility of the LbL assembly. PMID:25599567

  18. Skeletal muscle fiber type: using insights from muscle developmental biology to dissect targets for susceptibility and resistance to muscle disease.

    PubMed

    Talbot, Jared; Maves, Lisa

    2016-07-01

    Skeletal muscle fibers are classified into fiber types, in particular, slow twitch versus fast twitch. Muscle fiber types are generally defined by the particular myosin heavy chain isoforms that they express, but many other components contribute to a fiber's physiological characteristics. Skeletal muscle fiber type can have a profound impact on muscle diseases, including certain muscular dystrophies and sarcopenia, the aging-induced loss of muscle mass and strength. These findings suggest that some muscle diseases may be treated by shifting fiber type characteristics either from slow to fast, or fast to slow phenotypes, depending on the disease. Recent studies have begun to address which components of muscle fiber types mediate their susceptibility or resistance to muscle disease. However, for many diseases it remains largely unclear why certain fiber types are affected. A substantial body of work has revealed molecular pathways that regulate muscle fiber type plasticity and early developmental muscle fiber identity. For instance, recent studies have revealed many factors that regulate muscle fiber type through modulating the activity of the muscle regulatory transcription factor MYOD1. Future studies of muscle fiber type development in animal models will continue to enhance our understanding of factors and pathways that may provide therapeutic targets to treat muscle diseases. WIREs Dev Biol 2016, 5:518-534. doi: 10.1002/wdev.230 For further resources related to this article, please visit the WIREs website. PMID:27199166

  19. Targeted illumination and tracking using optical fiber probe for optogenetics application

    NASA Astrophysics Data System (ADS)

    Shinde, Anant; Perinchery, Sandeep M.; Matham, Murukeshan V.

    2016-03-01

    There was a renewed interest, during the recent years, in the imaging and tracking of targeted cells or organelles for a variety of biomedical and lab-on a chip applications that include particles movement. However, nonspecific illumination during tracking can have adverse effects such as heating, reduced image contrast and photo bleaching. In fact, current available tracking and imaging systems are unable to selectively illuminate the particle being tracked. To fill this void, we have developed a fiber optics based probe system incorporating a spatial light modulator (SLM) and an imaging fiber bundle for selective illumination on the targeted particle. A GRIN lens is attached at the distal endface of the image fiber bundle for optimised illumination and collection. A tracking algorithm is developed in order to enable controlled illumination through SLM to target the illumination point or location in accordance with the particle movement and size variation. Further with this probe, particles can be illuminated with light pulses of controllable duty cycle and frequency. The proposed methodology and developed probe have good significance and expected to find potential applications areas such as optogenetics, cell signalling studies, and lab-on a chip systems.

  20. Multiwavelength L-band fiber laser with bismuth-oxide EDF and photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Ramzia Salem, A. M.; Al-Mansoori, M. H.; Hizam, H.; Mohd Noor, S. B.; Abu Bakar, M. H.; Mahdi, M. A.

    2011-05-01

    A multiwavelength laser comb using a bismuth-based erbium-doped fiber and 50 m photonic crystal fiber is demonstrated in a ring cavity configuration. The fiber laser is solely pumped by a single 1455 nm Raman pump laser to exploit its higher power delivery compared to that of a single-mode laser diode pump. At 264 mW Raman pump power and 1 mW Brillouin pump power, 38 output channels in the L-band have been realized with an optical signal-to-noise ratio above 15 dB and a Stokes line spacing of 0.08 nm. The laser exhibits a tuning range of 12 nm and produces stable Stokes lines across the tuning range between Brillouin pump wavelengths of 1603 nm and 1615 nm.

  1. Innovative fabrication of the flower-like nanocomposite coating on a nitinol fiber through Fenton's oxidation for selective and sensitive solid-phase microextraction.

    PubMed

    Zhang, Min; Zhen, Qi; Wang, Huiju; Guo, Mei; Zhou, Shanshan; Wang, Xuemei; Du, Xinzhen

    2016-09-01

    A novel flower-like nanostructure was successfully in situ fabricated on the surface of nitinol wire through Fenton's oxidation for the first time. It was found that the densely immobilized coating on the surface of the nitinol fiber was composed of nickel and titanium oxide nanocomposite (NiO/TiO2NC). The NiO/TiO2NC coated fiber was used to extract aromatic compounds coupled with high performance liquid chromatography (HPLC) with UV detection and exhibited excellent extraction efficiency for polycyclic aromatic hydrocarbons (PAHs) with larger delocalized π-system among the studied analytes. Important factors affecting extraction efficiency of PAHs were examined. Under the optimized conditions, the calibration curves were linear in the range from 0.05 to 500μgL(-1) with correlation coefficients of R(2)≥0.999, and the lowest limit of detection of 0.006μgL(-1) was achieved for benzo[a]pyrene. Furthermore, the intra-day and inter-day precisions for the single fiber varied from 4.69% to 5.97% and from 5.28% to 6.32% for five replicates of PAHs at the spiking level of 50μgL(-1), respectively. The fiber-to-fiber precision for five fibers prepared in different batches ranged from 6.19% to 8.35%. The developed method was successfully applied to concentration and determination of target PAHs from real environmental water samples. Moreover, this novel nitinol-based fiber exhibited long lifespan. Therefore, the proposed fiber can be used as a promising candidate for a conventional fused silica-based fiber in SPME. PMID:27343598

  2. Thermo-oxidative stability studies of Celion 6000/PMR-15 unidirectional composites, PMR-15, and Celion 6000 fiber

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; Nowak, Gregory

    1988-01-01

    Experimental results on the influence of the thermooxidative resistance characteristics of the fiber and matrix resin on the thermal stability of isothermally aged Celion 6000/PMR-15 matrix resin composites are presented. SEM studies reveal that extreme oxidative erosion of the graphite fiber occurs at elevated temperatures in the presence of the polyimide matrix. The activation energy of oxidation of the composite was shown to be greater than those of the fiber and the matrix resin.

  3. Dissolution of Neptunium Oxide in Unirradiated Mark 53 Targets

    SciTech Connect

    Rudisill, T.S.

    2002-12-06

    Nine unirradiated Mark 53 targets currently stored at the K-Reactor must be dissolved to allow recovery of the neptunium content. The Mark 53 targets are an aluminum clad, neptunium oxide (NpO2)/aluminum metal cermet used for the production of plutonium-238. The targets will be dissolved in H-Canyon and blended with solutions generated from routine fuel dissolutions for purification by solvent extraction. The increased neptunium concentration should not have a significant effect on the neptunium decontamination factor achieved by the 1st cycle of solvent extraction; however, the neptunium content of the uranium product (1CU) will likely increase in proportion to the increase in the neptunium feed concentration. The recovered neptunium will be combined with the existing inventory of neptunium solution currently stored in H-Canyon. The combined inventory will undergo subsequent purification and conversion to an oxide for shipment to the Oak Ridge National Laboratory where plutonium- 238 will be manufactured using the High Flux Isotope Reactor.

  4. Oxidation of activated carbon fibers: Effect on pore size, surface chemistry, and adsorption properties

    SciTech Connect

    Mangun, C.L.; Benak, K.R.; Daley, M.A.; Economy, J.

    1999-12-01

    Activated carbon fibers (ACFs) were oxidized using both aqueous and nonaqueous treatments. As much as 29 wt% oxygen can be incorporated onto the pore surface in the form of phenolic hydroxyl, quinine, and carboxylic acid groups. The effect of oxidation on the pore size, pore volume, and the pore surface chemistry was thoroughly examined. The average micropore size is typically affected very little by aqueous oxidation while the micropore volume and surface area decreases with such a treatment. In contrast, the micropore size and micropore volume both increase with oxidation in air. Oxidation of the fibers produces surface chemistries in the pore that provide for enhanced adsorption of basic (ammonia) and polar (acetone) molecules at ambient and nonambient temperatures. The adsorption capacity of the oxidized fibers for acetone is modestly better than the untreated ACFs while the adsorption capacity for ammonia can increase up to 30 times compared to untreated ACFs. The pore surface chemical makeup was analyzed using elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and X-ray photoelectron spectroscopy (XPS).

  5. Niacin supplementation increases the number of oxidative type I fibers in skeletal muscle of growing pigs

    PubMed Central

    2013-01-01

    Background A recent study showed that niacin supplementation counteracts the obesity-induced muscle fiber switching from oxidative type I to glycolytic type II and increases the number of type I fibers in skeletal muscle of obese Zucker rats. These effects were likely mediated by the induction of key regulators of fiber transition, PGC-1α and PGC-1β, leading to muscle fiber switching and up-regulation of genes involved in mitochondrial fatty acid import and oxidation, citrate cycle, oxidative phosphorylation, mitochondrial biogenesis. The aim of the present study was to investigate whether niacin supplementation causes type II to type I muscle and changes the metabolic phenotype of skeletal muscles in growing pigs. Results 25 male, 11 wk old crossbred pigs (Danzucht x Pietrain) with an average body weight of 32.8 ± 1.3 (mean ± SD) kg were randomly allocated to two groups of 12 (control group) and 13 pigs (niacin group) which were fed either a control diet or a diet supplemented with 750 mg niacin/kg diet. After 3 wk, the percentage number of type I fibers in three different muscles (M. longissismus dorsi, M. quadriceps femoris, M. gastrocnemius) was greater in the niacin group and the percentage number of type II fibers was lower in the niacin group than in the control group (P < 0.05). The mRNA levels of PGC-1β and genes involved in mitochondrial fatty acid catabolism (CACT, FATP1, OCTN2), citrate cycle (SDHA), oxidative phosphorylation (COX4/1, COX6A1), and thermogenesis (UCP3) in M. longissimus dorsi were greater in the niacin group than in the control group (P < 0.05). Conclusions The study demonstrates that niacin supplementation induces type II to type I muscle fiber switching, and thereby an oxidative metabolic phenotype of skeletal muscle in pigs. Given that oxidative muscle types tend to develop dark, firm and dry pork in response to intense physical activity and/or high psychological stress levels preslaughter, a niacin

  6. Thermo-oxidative stability of graphite fiber/PMR-15 polyimide composites at 350 deg C

    NASA Technical Reports Server (NTRS)

    Scola, D. A.

    1985-01-01

    A series of graphite fiber/PMR-15 polyimide composites were subjected to isothermal aging at 350 C in flowing air (100 cc/min and 1000 cc/min) over a 520 hr time period. The graphite fibers were analyzed by ISS/SIMS techniques before composite fabrication. Fibers exposed at the surface of the composite due to the isothermal aging process were also analyzed by the ISS/SIMS method. Component and composite weight less studies were also conducted for similarly exposed materials. Optical micrograph investigations of composites to follow the progress of the thermo-oxidative process were also conducted. Flexural and interlaminar shear strengths of the imaged and aged composites were measured. The relationship of component and composite properties as they relate to the thermo-oxidative behavior of the materials was discussed.

  7. Adrenaline and noradrenaline: protectors against oxidative stress or molecular targets?

    PubMed

    Álvarez-Diduk, Ruslán; Galano, Annia

    2015-02-26

    Density functional theory was used to investigate the potential role of neurotransmitters adrenaline and noradrenaline regarding oxidative stress. It is predicted that they can be efficient as free radical scavengers both in lipid and aqueous media, with the main reaction mechanism being the hydrogen transfer and the sequential proton loss electron transfer, respectively. Despite the polarity of the environment, adrenaline and noradrenaline react with (•)OOH faster than Trolox, which suggests that they are better peroxyl radical scavengers than the reference compound. Both catecholamines are also proposed to be capable of efficiently inhibiting the oxidative stress induced by copper(II)-ascorbate mixtures, and the (•)OH production via Haber-Weiss reaction, albeit the effects on the later are only partial. They exert such beneficial effects by sequestering Cu(II) ions. In summary, these catecholamines can be capable of reducing oxidative stress, by scavenging free radicals and by sequestering metal ions. However, at the same time they might lose their functions in the process due to the associated structural modifications. Consequently, adrenaline and noradrenaline can be considered as both protectors and molecular targets of oxidative stress. Fortunately, under the proper conditions, both catecholamines can be regenerated to their original form so their functions are restored. PMID:25646569

  8. Construction and performance of a plastic scintillating fiber target for a rare kaon decay experiment

    SciTech Connect

    Frank, J.S.; Strand, R.C.

    1988-01-01

    A K/sup +/ stopping target consisting of 2269 plastic fibers, 2 mm diameter and 3.12 m long has been installed in an experiment searching for the rare decay K/sup +/ to ..pi nu../bar nu/ at Brookhaven National Laboratory. The fibers are bundled onto 379 photomultiplier tube and base assemblies with single photoelectron resolution. After routing to the counting room, the signals are amplified and then distributed to TDC's and high-pass filter circuits that provide signals to ADC's and to fan-ins that provide a target energy-sum pulse used in the fast triggering logic. A minimum ionizing particle 3 m from the photomultiplier yields 1 photoelectron/mm path. The target provides transverse spatial resolution of 4 mm (FWHM) for the vertex of the K/sup +/ decay and 2 ns timing resolution (FWHM) on the difference between the K/sup +/ stop and the subsequent decay. Details of the target construction and operating performance are provided. 4 refs., 7 figs.

  9. Oxidative stress and abdominal aortic aneurysm: potential treatment targets.

    PubMed

    Emeto, Theophilus I; Moxon, Joseph V; Au, Minnie; Golledge, Jonathan

    2016-03-01

    Abdominal aortic aneurysm (AAA) is a significant cause of mortality in older adults. A key mechanism implicated in AAA pathogenesis is inflammation and the associated production of reactive oxygen species (ROS) and oxidative stress. These have been suggested to promote degradation of the extracellular matrix (ECM) and vascular smooth muscle apoptosis. Experimental and human association studies suggest that ROS can be favourably modified to limit AAA formation and progression. In the present review, we discuss mechanisms potentially linking ROS to AAA pathogenesis and highlight potential treatment strategies targeting ROS. Currently, none of these strategies has been shown to be effective in clinical practice. PMID:26814202

  10. Fiber-Optic SPR Immunosensors Tailored To Target Epithelial Cells through Membrane Receptors.

    PubMed

    Malachovská, Viera; Ribaut, Clotilde; Voisin, Valérie; Surin, Mathieu; Leclère, Philippe; Wattiez, Ruddy; Caucheteur, Christophe

    2015-06-16

    We report, for the first time, the use of a surface plasmon resonance (SPR) fiber-optic immunosensor for selective cellular detection through membrane protein targeting. The sensor architecture lies on gold-coated tilted fiber Bragg gratings (Au-coated TFBGs) photoimprinted in the fiber core via a laser technique. TFBGs operate in the near-infrared wavelength range at ∼1550 nm, yielding optical and SPR sensing characteristics that are advantageous for the analyses of cellular bindings and technical compatibility with relatively low-cost telecommunication-grade measurement devices. In this work, we take consider their numerous assets to figure out their ability to selectively detect intact epithelial cells as analytes in cell suspensions in the range of 2-5 × 10(6) cells mL(-1). For this, the probe was first thermally annealed to ensure a strong adhesion of the metallic coating to the fiber surface. Its surface was then functionalized with specific monoclonal antibodies via alkanethiol self-assembled monolayers (SAMs) against extracellular domain of epidermal growth factor receptors (EGFRs) and characterized by peak force tapping atomic force microscopy. A differential diagnosis has been demonstrated between two model systems. The developed immunosensors were able to monitor, in real time, the specific attachment of single intact cells in concentrations from 3 × 10(6) cells mL(-1). Such results confirm that the developed probe fits the lab-on-fiber technology and has the potential to be used as a disposable device for in situ and real-time clinical diagnosis. PMID:25962700

  11. The effects of pre-oxidation heating rate on bio-based carbon fibers and its surface repair

    NASA Astrophysics Data System (ADS)

    Wu, H.; Cheng, L. F.; Fan, S. W.; Yuan, X. W.; Bhattacharyya, D.

    2015-03-01

    Low-cost carbon fibers (CFs) are fabricated from jute fibers after pre-oxidation, carbonization and surface repair. This paper investigates the effects of pre-oxidation heating rate on jute fibers, and explores a repair method for surface defects of CFs in C/C composite. The results show the reaction mechanism of jute fibers in air is not changed at higher pre-oxidation heating rates while a low heating rate is still required as the oxidation of jute fibers cannot be fully achieved under rapid heating. The tensile strength of CFs increases after repair with a 5% phenolic resin solution. Jute-based CFs play a positive role in C/C composite performance through crack bridging and deflection.

  12. Single Crystal Fibers of Yttria-Stabilized Cubic Zirconia with Ternary Oxide Additions

    NASA Technical Reports Server (NTRS)

    Ritzert, F. J.; Yun, H. M.; Miner, R. V.

    1997-01-01

    Single crystal fibers of yttria (Y2O3)-stabilized cubic zirconia, (ZrO2) with ternary oxide additions were grown using the laser float zone fiber processing technique. Ternary additions to the ZrO2-Y2O3 binary system were studied aimed at increasing strength while maintaining the high coefficient of thermal expansion of the binary system. Statistical methods aided in identifying the most promising ternary oxide candidate (Ta2O5, Sc2O3, and HfO2) and optimum composition. The yttria, range investigated was 14 to 24 mol % and the ternary oxide component ranged from 1 to 5 mol %. Hafnium oxide was the most promising ternary oxide component based on 816 C tensile strength results and ease of fabrication. The optimum composition for development was 81 ZrO2-14 Y203-5 HfO2 based upon the same elevated temperature strength tests. Preliminary results indicate process improvements could improve the fiber performance. We also investigated the effect of crystal orientation on strength.

  13. Destruction of monocrystalline silicon with nanosecond pulsed fiber laser accompanied by the oxidation of ablation microparticles

    NASA Astrophysics Data System (ADS)

    Veiko, V. P.; Skvortsov, A. M.; Huynh, C. T.; Petrov, A. A.

    2013-11-01

    In this work, we report an observation of process of local destruction monocrystalline silicon with a scanning beam irradiation of pulse ytterbium fiber laser with a wavelength λ= 1062 nm, accompanied by the oxidation of ablation microparticles. It is shown that depending on the power density of irradiation was observed a large scatter size of the microparticles. From a certain average power density is observed beginning oxidation particulate emitted from the surface of the irradiated area. By varying the parameters of the laser beam such as scanning speed, pulse repetition rate, overlap of laser spot, radiation dose can be achieved almost complete oxidation of all formed during the ablation of microparticles.

  14. Sub-micrometer sized yttrium oxide fibers prepared through hydrothermal reaction

    SciTech Connect

    Li, Nan; Yanagisawa, Kazumichi

    2011-03-15

    Research highlights: {yields} Y{sub 2}O{sub 3} fibers were synthesized by hydrothermal reaction followed by calcination. {yields} Y(OH){sub x}Cl{sub 3-x}.yH{sub 2}O was received from hydrothermal reaction. {yields} Y{sub 2}O{sub 3} fibers showed outstanding high-temperature stability. -- Abstract: Yttrium oxide fibers have been synthesized via hydrothermal reaction and subsequent thermal treatment using yttrium chloride as precursor. The products before and after the thermal treatment were characterized by powder X-ray diffractions (XRD), scanning electron microscopy (SEM), ion-chromatograph analysis, and thermogravimetry and differential thermal analysis (TG-DTA). The fiber diameter ranged from 100 to 300 nm, while the length was up to tens of microns. It was found that the chemical composition and morphology of the products were closely related to the pH value of reaction solution, and fibrous products could be obtained at pH 9.5-10.25. These oxide fibers exhibited outstanding high-temperature stability, which maintained their morphology at temperature up to 1400 {sup o}C.

  15. Hybrid Silk Fibers Dry-Spun from Regenerated Silk Fibroin/Graphene Oxide Aqueous Solutions.

    PubMed

    Zhang, Chao; Zhang, Yaopeng; Shao, Huili; Hu, Xuechao

    2016-02-10

    Regenerated silk fibroin (RSF)/graphene oxide (GO) hybrid silk fibers were dry-spun from a mixed dope of GO suspension and RSF aqueous solution. It was observed that the presence of GO greatly affect the viscosity of RSF solution. The RSF/GO hybrid fibers showed from FTIR result lower β-sheet content compared to that of pure RSF fibers. The result of synchrotron radiation wide-angle X-ray diffraction showed that the addition of GO confined the crystallization of silk fibroin (SF) leading to the decrease of crystallinity, smaller crystallite size, and new formation of interphase zones in the artificial silks. Synchrotron radiation small-angle X-ray scattering also proved that GO sheets in the hybrid silks and blended solutions were coated with a certain thickness of interphase zones due to the complex interaction between the two components. A low addition of GO, together with the mesophase zones formed between GO and RSF, enhanced the mechanical properties of hybrid fibers. The highest breaking stress of the hybrid fibers reached 435.5 ± 71.6 MPa, 23% improvement in comparison to that of degummed silk and 72% larger than that of pure RSF silk fiber. The hybrid RSF/GO materials with good biocompatibility and enhanced mechanical properties may have potential applications in tissue engineering, bioelectronic devices, or energy storage. PMID:26784289

  16. Vector rectangular-shape laser based on reduced graphene oxide interacting with a long fiber taper.

    PubMed

    Gao, Lei; Zhu, Tao; Huang, Wei; Zeng, Jing

    2014-10-01

    A vector dual-wavelength rectangular-shape laser (RSL) based on a long fiber taper deposited with reduced graphene oxide is proposed, where nonlinearity is enhanced due to a large evanescent-field-interacting length and strong field confinement of an 8 mm fiber taper with a waist diameter of 4 μm. Graphene flakes are deposited uniformly on the taper waist with light pressure effect, so this structure guarantees both excellent saturable absorption and high nonlinearity. The RSL with a repetition rate of 7.9 MHz shows fast polarization switching in two orthogonal polarization directions, and temporal and spectral characteristics are investigated. PMID:25322232

  17. Modification of surface oxide layers of titanium targets for increasing lifetime of neutron tubes

    NASA Astrophysics Data System (ADS)

    Zakharov, A. M.; Dvoichenkova, O. A.; Evsin, A. E.

    2015-12-01

    The peculiarities of interaction of hydrogen ions with a titanium target and its surface oxide layer were studied. Two ways of modification of the surface oxide layers of titanium targets for increasing the lifetime of neutron tubes were proposed: (1) deposition of an yttrium oxide barrier layer on the target surface; (2) implementation of neutron tube work regime in which the target is irradiated with ions with energies lower than 1000 eV between high-energy ion irradiation pulses.

  18. Modification of surface oxide layers of titanium targets for increasing lifetime of neutron tubes

    SciTech Connect

    Zakharov, A. M. Dvoichenkova, O. A.; Evsin, A. E.

    2015-12-15

    The peculiarities of interaction of hydrogen ions with a titanium target and its surface oxide layer were studied. Two ways of modification of the surface oxide layers of titanium targets for increasing the lifetime of neutron tubes were proposed: (1) deposition of an yttrium oxide barrier layer on the target surface; (2) implementation of neutron tube work regime in which the target is irradiated with ions with energies lower than 1000 eV between high-energy ion irradiation pulses.

  19. Facile synthesis of graphite-reduced graphite oxide core-sheath fiber via direct exfoliation of carbon fiber for supercapacitor application.

    PubMed

    Ji, Qinghua; Zhao, Xu; Liu, Huijuan; Guo, Lin; Qu, Jiuhui

    2014-06-25

    A graphite-reduced graphite oxide (rGO) core-sheath structured fiber was synthesized through chemical exfoliation of graphitic carbon fiber. The graphitic carbon fiber was oxidized to form a graphite-graphite oxide core-sheath fiber and followed by thermal exfoliation to form a graphite-rGO core-sheath fiber. The core-sheath fiber with a three-dimensionally (3D) structured rGO sheath possesses a high surface area and pore size around 5.5 nm. A two-electrode supercapacitor constructed with this core-sheath fiber-based paper exhibited a high specific capacitance (140 F g(-1) at a current density of 1 A g(-1)), high power density of 45 kW/kg, and good cycling stability (10% capacity loss after 3000 cycles). The surface area normalized capacitance reached as high as 59.4 μF cm(-2), indicating the effective use of surface area. The low equivalent series resistance value of 0.45 ohm in the Nyquist plot indicates an extremely small resistance between the graphite core and rGO sheet sheath. The hierarchical three-dimensional structure enables one to maximize the advantages of both graphite and rGO sheets. The 3D-structured rGO sheets sheath with regular pore structure is favorable for ion diffusion due to its interconnected porous system, while the graphite core provides an electron transport pathway with high conductivity. PMID:24820530

  20. Sliding durability of two carbide-oxide candidate high temperature fiber seal materials in air to 900 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Steinetz, Bruce M.

    1992-01-01

    A test program to determine the friction and wear properties of two complex carbide oxide ceramic fibers for high temperature sliding seal applications is described. The fibers are based on Si, C, O, and Ti or Si, C, N, and O ceramic systems. Pin on disk tests using ceramic fiber covered pins and Inconel 718 disks, were conducted in air from 25 to 900 C to evaluate potential seal materials. This testing procedure was used in a previous study of oxide ceramic fibers which were found to exhibit wear behavior based predominantly on their mechanical properties. Like the oxide fibers tested previously, these carbide oxide ceramic fibers, show an increase in friction and wear with increased test temperature. At room temperature, the wear behavior seems to be based upon mechanical properties, namely tensile strength. At 500 and especially 900 C, the fibers wear by both mechanical fracture and by oxidative type wear. Based upon post test microscopic and x ray analyses, interaction between the fiber constituents and elements transferred from the counterface, namely Ni and Cr, may have occurred enhancing the tribochemical wear process. These results are interpreted.

  1. Modeling the Effect of Oxidation on Tensile Strength of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    An analytical method has been developed to investigate the effect of oxidation on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs). The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The fiber strength degradation model and oxidation region propagation model have been adopted to analyze the oxidation effect on tensile strength of the composite, which is controlled by diffusion of oxygen gas through matrix cracks. Under tensile loading, the fibers failure probabilities were determined by combining oxidation model and fiber statistical failure model based on the assumption that fiber strength is subjected to two-parameter Weibull distribution and the loads carried by broken and intact fibers statisfy the global load sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength considering oxidation time and temperature have been analyzed.

  2. Stoichiometry control of complex oxides by sequential pulsed-laser deposition from binary-oxide targets

    SciTech Connect

    Herklotz, A.; Dörr, K.; Ward, T. Z.; Eres, G.; Christen, H. M.; Biegalski, M. D.

    2015-03-30

    To have precise atomic layer control over interfaces, we examine the growth of complex oxides through the sequential deposition from binary targets by pulsed laser deposition. In situ reflection high-energy electron diffraction (RHEED) is used to control the growth and achieve films with excellent structural quality. The growth from binary oxide targets is fundamentally different from single target growth modes and shows more similarities to shuttered growth by molecular beam epitaxy. The RHEED intensity oscillations of non-stoichiometric growth are consistent with a model of island growth and accumulation of excess material on the surface that can be utilized to determine the correct stoichiometry for growth. Correct monolayer doses can be determined through an envelope frequency in the RHEED intensity oscillations. In order to demonstrate the ability of this growth technique to create complex heterostructures, the artificial n = 2 and 3 Sr{sub n+1}Ti{sub n}O{sub 3n+1} Ruddlesden-Popper phases are grown with good long-range order. This method enables the precise unit-cell level control over the structure of perovskite-type oxides, and thus the growth of complex materials with improved structural quality and electronic functionality.

  3. Stoichiometry control of complex oxides by sequential pulsed-laser deposition from binary-oxide targets

    SciTech Connect

    Herklotz, A.; Dörr, Kathrin; Ward, T. Z.; Eres, G.; Christen, H. M.; Biegalski, Michael D.

    2015-04-03

    In this paper, to have precise atomic layer control over interfaces, we examine the growth of complex oxides through the sequential deposition from binary targets by pulsed laser deposition. In situ reflection high-energy electron diffraction (RHEED) is used to control the growth and achieve films with excellent structural quality. The growth from binary oxide targets is fundamentally different from single target growth modes and shows more similarities to shuttered growth by molecular beam epitaxy. The RHEED intensity oscillations of non-stoichiometric growth are consistent with a model of island growth and accumulation of excess material on the surface that can be utilized to determine the correct stoichiometry for growth. Correct monolayer doses can be determined through an envelope frequency in the RHEED intensity oscillations. In order to demonstrate the ability of this growth technique to create complex heterostructures, the artificial n = 2 and 3 Sr n +1Ti n O3 n +1 Ruddlesden-Popper phases are grown with good long-range order. Finally, this method enables the precise unit-cell level control over the structure of perovskite-type oxides, and thus the growth of complex materials with improved structural quality and electronic functionality.

  4. Stoichiometry control of complex oxides by sequential pulsed-laser deposition from binary-oxide targets

    DOE PAGESBeta

    Herklotz, A.; Dörr, Kathrin; Ward, T. Z.; Eres, G.; Christen, H. M.; Biegalski, Michael D.

    2015-04-03

    In this paper, to have precise atomic layer control over interfaces, we examine the growth of complex oxides through the sequential deposition from binary targets by pulsed laser deposition. In situ reflection high-energy electron diffraction (RHEED) is used to control the growth and achieve films with excellent structural quality. The growth from binary oxide targets is fundamentally different from single target growth modes and shows more similarities to shuttered growth by molecular beam epitaxy. The RHEED intensity oscillations of non-stoichiometric growth are consistent with a model of island growth and accumulation of excess material on the surface that can bemore » utilized to determine the correct stoichiometry for growth. Correct monolayer doses can be determined through an envelope frequency in the RHEED intensity oscillations. In order to demonstrate the ability of this growth technique to create complex heterostructures, the artificial n = 2 and 3 Sr n +1Ti n O3 n +1 Ruddlesden-Popper phases are grown with good long-range order. Finally, this method enables the precise unit-cell level control over the structure of perovskite-type oxides, and thus the growth of complex materials with improved structural quality and electronic functionality.« less

  5. Stressed-Oxidation Lifetime of Different SiC Fiber, CVI Matrix SiC Minicomposites in Air

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Martinez-Fernandez, Julian

    1998-01-01

    The stressed-oxidation lifetime properties of several minicomposites composed of single fiber tows with a CVI SiC matrix were compared. The minicomposites were made up of Nicalon(Tm) and Hi-Nicalon(Tm) SiC fibers with carbon or BN interphases. Constant load stress-rupture tests were performed between 600 and 13000 C in air for all of the minicomposite systems. Cyclic load testing was performed on the Hi-Nicalon minicomposite systems. The factors controlling the different lifetime behaviors: fiber rupture properties, interphase oxidation, fiber degradation, and fiber-matrix bonding, are discussed in light of different minicomposite constituents. All of the systems were subject to intermediate temperature embrittlement. The Hi-Nicalon fiber, BN interphase system, performed the best for constant load conditions. For cyclic load conditions, both the BN- interphase and C-interphase minicomposites displayed poor, but different failure behavior.

  6. Oxidation and temperature effects on the interfacial shear strength in SCS-6 fiber-reinforced reaction-bonded silicon nitride

    SciTech Connect

    Guermazi, M.

    1995-01-01

    The fiber/matrix interfacial shear strength of Textron SCS-6 SiC-fiber-reinforced reaction-bonded Si{sub 3}N{sub 4} (RBSN) was studied as a function of temperature after oxidation for 24 h at 600 C. Fiber push-out experiments were conducted using a diamond indenter in a high-temperature microhardness tester under vacuum. The interfacial shear strength increased with temperature because of the relief of residual tensile stresses arising from the difference in thermal expansion coefficients between the fiber and the matrix. Most of sublayer 2 of the fiber outer coating, which mainly consisted of carbon in the form of BSU (basic structure unit) aggregates, had disappeared after the heat treatment of the composite. Oxidation resulted in severe changes in the fiber outer coating and caused a lower interfacial shear strength with respect to that of the unoxidized composite.

  7. In situ growth of silver nanoparticles on TEMPO-oxidized jute fibers by microwave heating.

    PubMed

    Cao, Xinwang; Ding, Bin; Yu, Jianyong; Al-Deyab, Salem S

    2013-01-30

    Cellulose fibers deposited with metallic nanoparticles as one kind of renewable, biocompatible and antimicrobial nanomaterials evoke much interest because of their versatility in various applications. Herein, for the first time, a facile, simple and rapid method was developed to fabricate TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) selectively oxidized jute fibers in situ deposited with silver nanoparticles in the absence of reducing reagents. The average size of silver nanoparticles deposited on the fibers is 50.0 ± 2.0 nm by microwave heating for 5 min and 90.0 ± 4.7 nm for 10 min heating sample, respectively. The versatile jute-silver nanoparticles nanocomposites with superior thermal stability and high crystallinity would be particularly useful for applications in the public health care and biomedical fields. PMID:23218337

  8. Enhanced strain and temperature sensing by reduced graphene oxide coated etched fiber Bragg gratings.

    PubMed

    S, Sridevi; Vasu, K S; Asokan, S; Sood, A K

    2016-06-01

    This Letter reports on an etched fiber Bragg grating (eFBG) sensor coated with reduced graphene oxide (RGO) having enhanced sensitivity for physical parameters such as strain and temperature. The synergetic effect of the changes in grating pitch and refractive index of RGO with change in temperature or strain enhances the shift in Bragg wavelength (λB). The RGO-coated eFBG sensors exhibit a strain sensitivity of 5.5 pm/μϵ (∼5 times that of bare fiber Bragg gratings) and temperature sensitivity of 33 pm/°C (∼3 times that of bare fiber Bragg gratings). The resolutions of ∼1  μϵ and ∼0.3°C have been obtained for strain and temperature respectively, using RGO-coated eFBG sensors. PMID:27244425

  9. Laser ablation of Drosophila embryonic motoneurons causes ectopic innervation of target muscle fibers

    NASA Technical Reports Server (NTRS)

    Chang, T. N.; Keshishian, H.

    1996-01-01

    We have tested the effects of neuromuscular denervation in Drosophila by laser-ablating the RP motoneurons in intact embryos before synaptogenesis. We examined the consequences of this ablation on local synaptic connectivity in both 1st and 3rd instar larvae. We find that the partial or complete loss of native innervation correlates with the appearance of alternate inputs from neighboring motor endings and axons. These collateral inputs are found at ectopic sites on the denervated target muscle fibers. The foreign motor endings are electrophysiologically functional and are observed on the denervated muscle fibers by the 1st instar larval stage. Our data are consistent with the existence of a local signal from the target environment, which is regulated by innervation and influences synaptic connectivity. Our results show that, despite the stereotypy of Drosophila neuromuscular connections, denervation can induce local changes in connectivity in wild-type Drosophila, suggesting that mechanisms of synaptic plasticity may also be involved in normal Drosophila neuromuscular development.

  10. Targeting oxidative stress in surgery: effects of ageing and therapy.

    PubMed

    Pepe, Salvatore; Leong, Jee-Yoong; Van der Merwe, Juliana; Marasco, Silvana F; Hadj, Anthony; Lymbury, Robyn; Perkins, Anthony; Rosenfeldt, Franklin L

    2008-07-01

    In the current era cardiac surgeons are being called upon to operate upon older, sicker patients. The effect is to augment oxidative stress and increase the rate of post-operative complications and ultimately mortality. We have developed antioxidant-based pre-treatment regimes initially based on coenzyme Q(10). A randomised trial of coenzyme Q(10) in elective cardiac surgery patients demonstrated augmented plasma and cardiac mitochondrial membrane coenzyme Q(10) content, improved mitochondrial respiration and increased myocardial tolerance of oxidative stress. The addition of omega-3 polyunsaturated fatty acids, alpha-lipoic acid, selenium and magnesium orotate in a second clinical trial, improved post-operative recovery with demonstrable reductions in myocardial damage, rate of atrial fibrillation and length of hospital stay. Finally we performed a pilot study of this combined metabolic therapy regimen to which we added preoperative physical exercise and mental stress reduction with indications of further improvements in post-operative recovery. We conclude that simultaneously targeting a number of key deficiencies with a metabolic formulation prior to surgery results in peri- and post-operative clinical and economic benefits. PMID:18468827

  11. Rapid oxidation/stabilization technique for carbon foams, carbon fibers and C/C composites

    DOEpatents

    Tan, Seng; Tan, Cher-Dip

    2004-05-11

    An enhanced method for the post processing, i.e. oxidation or stabilization, of carbon materials including, but not limited to, carbon foams, carbon fibers, dense carbon-carbon composites, carbon/ceramic and carbon/metal composites, which method requires relatively very short and more effective such processing steps. The introduction of an "oxygen spill over catalyst" into the carbon precursor by blending with the carbon starting material or exposure of the carbon precursor to such a material supplies required oxygen at the atomic level and permits oxidation/stabilization of carbon materials in a fraction of the time and with a fraction of the energy normally required to accomplish such carbon processing steps. Carbon based foams, solids, composites and fiber products made utilizing this method are also described.

  12. Oxidation behavior of single-crystal Al2O3-fiber-reinforced Ni3Al-based composites

    NASA Astrophysics Data System (ADS)

    Nourbakhsh, S.; Rhee, W. H.; Sahin, O.; Margolin, H.

    1994-07-01

    A series of single-crystal Al2O3-fiber-reinforced Ni3Al-based intermetallic matrix composites were fabricated by pressure casting. The matrices employed were binary Ni3Al, Ni3Al-0.5 at. pct Cr, and Ni3Al-0.34 at. pct Zr. The development of microstructure upon oxidation in air at either 1100 °C or 1200 °C was investigated by optical, scanning, and transmission electron microscopy. In air-oxidized binary Ni3Al, some of the fibers were fully or partially covered with a layer of oxide. A weak fiber/matrix bond in this system, which led to fiber debonding during composite processing, is believed to be responsible for the ingress of O into the composite and oxidation of the matrix in the debonded regions at the fiber/matrix interface. Addition of Cr to Ni3Al resulted in an almost threefold increase in fiber/matrix bond strength. No oxidation of the interface was observed. A thick layer of oxide was formed around all the fibers when the composite was thermally cycled prior to isothermal annealing. Addition of Zr to Ni3Al resulted in the formation of a layer of ZrO2 on the surface of the fibers during composite processing. The ZrO2 layer provided a fast path for the diffusion of O, which led to the formation of a rootlike oxide structure around the fibers. The rootlike structure consisted of a network of Al2O3-covered ZrO2.

  13. Subcellular targeting and trafficking of nitric oxide synthases

    PubMed Central

    Oess, Stefanie; Icking, Ann; Fulton, David; Govers, Roland; Müller-Esterl, Werner

    2006-01-01

    Unlike most other endogenous messengers that are deposited in vesicles, processed on demand and/or secreted in a regulated fashion, NO (nitric oxide) is a highly active molecule that readily diffuses through cell membranes and thus cannot be stored inside the producing cell. Rather, its signalling capacity must be controlled at the levels of biosynthesis and local availability. The importance of temporal and spatial control of NO production is highlighted by the finding that differential localization of NO synthases in cardiomyocytes translates into distinct effects of NO in the heart. Thus NO synthases belong to the most tightly controlled enzymes, being regulated at transcriptional and translational levels, through co- and post-translational modifications, by substrate availability and not least via specific sorting to subcellular compartments, where they are in close proximity to their target proteins. Considerable efforts have been made to elucidate the molecular mechanisms that underlie the intracellular targeting and trafficking of NO synthases, to ultimately understand the cellular pathways controlling the formation and function of this powerful signalling molecule. In the present review, we discuss the mechanisms and triggers for subcellular routing and dynamic redistribution of NO synthases and the ensuing consequences for NO production and action. PMID:16722822

  14. Targeted detection of murine colonic dysplasia in vivo with flexible multispectral scanning fiber endoscopy

    NASA Astrophysics Data System (ADS)

    Joshi, Bishnu P.; Miller, Sharon J.; Lee, Cameron; Gustad, Adam; Seibel, Eric J.; Wang, Thomas D.

    2012-02-01

    We demonstrate a multi-spectral scanning fiber endoscope (SFE) that collects fluorescence images in vivo from three target peptides that bind specifically to murine colonic adenomas. This ultrathin endoscope was demonstrated in a genetically engineered mouse model of spontaneous colorectal adenomas based on somatic Apc (adenomatous polyposis coli) gene inactivation. The SFE delivers excitation at 440, 532, 635 nm with <2 mW per channel. The target 7-mer peptides were conjugated to visible organic dyes, including 7-Diethylaminocoumarin-3-carboxylic acid (DEAC) (λex=432 nm, λem=472 nm), 5-Carboxytetramethylrhodamine (5-TAMRA) (λex=535 nm, λem=568 nm), and CF-633 (λex=633 nm, λem=650 nm). Target peptides were first validated using techniques of pfu counting, flow cytometry and previously established methods of fluorescence endoscopy. Peptides were applied individually or in combination and detected with fluorescence imaging. The ability to image multiple channels of fluorescence concurrently was successful for all three channels in vitro, while two channels were resolved simultaneously in vivo. Selective binding of the peptide was evident to adenomas and not to adjacent normal-appearing mucosa. Multispectral wide-field fluorescence detection using the SFE is achievable, and this technology has potential to advance early cancer detection and image-guided therapy in human patients by simultaneously visualizing multiple over expressed molecular targets unique to dysplasia.

  15. Thermal oxidation induced degradation of carbon fiber reinforced composites and carbon nanotube sheet enhanced fiber/matrix interface for high temperature aerospace structural applications

    NASA Astrophysics Data System (ADS)

    Haque, Mohammad Hamidul

    Recent increase in the use of carbon fiber reinforced polymer matrix composite, especially for high temperature applications in aerospace primary and secondary structures along with wind energy and automotive industries, have generated new challenges to predict its failure mechanisms and service life. This dissertation reports the experimental study of a unidirectional carbon fiber reinforced bismaleimide (BMI) composites (CFRC), an excellent candidate for high temperature aerospace components, undergoing thermal oxidation at 260 °C in air for over 3000 hours. The key focus of the work is to investigate the mechanical properties of the carbon fiber BMI composite subjected to thermal aging in three key aspects - first, studying its bulk flexural properties (in macro scale), second, characterizing the crack propagation along the fiber direction, representing the interfacial bonding strength between fiber and matrix (in micro scale), and third, introducing nano-structured materials to modify the interface (in nano scale) between the carbon fiber and BMI resin and mechanical characterization to study its influence on mitigating the aging effect. Under the first category, weight loss and flexural properties have been monitored as the oxidation propagates through the fiber/matrix interface. Dynamic mechanical analysis and micro-computed tomography analysis have been performed to analyze the aging effects. In the second category, the long-term effects of thermal oxidation on the delamination (between the composite plies) and debonding (between fiber and matrix) type fracture toughness have been characterized by preparing two distinct types of double cantilever beam specimens. Digital image correlation has been used to determine the deformation field and strain distribution around the crack propagation path. Finally the resin system and the fiber/matrix interface have been modified using nanomaterials to mitigate the degradations caused by oxidation. Nanoclay modified

  16. ReaxFF Study of the Oxidation of Softwood Lignin in View of Carbon Fiber Production

    SciTech Connect

    Beste, Ariana

    2014-01-01

    We investigate the oxidative, thermal conversion of softwood lignin by performing molecular dynamics simulations based on a reactive force field (ReaxFF). The lignin samples are constructed from coniferyl alcohol units, which are connected through linkages that are randomly selected from a natural distribution of linkages in softwood. The goal of this work is to simulate the oxidative stabilization step during carbon fiber production from lignin precursor. We find that at simulation conditions where stabilization reactions occur, the lignin fragments have already undergone extensive degradation. The 5-5 linkage shows the highest reactivity towards cyclization and dehydrogenation.

  17. ReaxFF Study of the Oxidation of Softwood Lignin in View of Carbon Fiber Production

    DOE PAGESBeta

    Beste, Ariana

    2014-10-06

    We investigate the oxidative, thermal conversion of softwood lignin by performing molecular dynamics simulations based on a reactive force field (ReaxFF). The lignin samples are constructed from coniferyl alcohol units, which are connected through linkages that are randomly selected from a natural distribution of linkages in softwood. The goal of this work is to simulate the oxidative stabilization step during carbon fiber production from lignin precursor. We find that at simulation conditions where stabilization reactions occur, the lignin fragments have already undergone extensive degradation. The 5-5 linkage shows the highest reactivity towards cyclization and dehydrogenation.

  18. Nitric oxide targets oligodendrocytes and promotes their morphological differentiation

    PubMed Central

    Garthwaite, Giti; Hampden-Smith, Kathryn; Wilson, Gary W; Goodwin, David A; Garthwaite, John

    2015-01-01

    In the central nervous system, nitric oxide (NO) transmits signals from one neurone to another, or from neurones to astrocytes or blood vessels, but the possibility of oligodendrocytes being physiological NO targets has been largely ignored. By exploiting immunocytochemistry for cGMP, the second messenger generated on activation of NO receptors, oligodendrocytes were found to respond to both exogenous and endogenous NO in cerebellar slices from rats aged 8 days to adulthood. Atrial natriuretic peptide, which acts on membrane-associated guanylyl cyclase-coupled receptors, also raised oligodendrocyte cGMP in cerebellar slices. The main endogenous source of NO accessing oligodendrocytes appeared to be the neuronal NO synthase isoform, which was active even under basal conditions and in a manner that was independent of glutamate receptors. Oligodendrocytes in brainstem slices were also shown to be potential NO targets. In contrast, in the optic nerve, oligodendrocyte cGMP was raised by natriuretic peptides but not NO. When cultures of cerebral cortex were continuously exposed to low NO concentrations (estimated as 40–90 pM), oligodendrocytes responded with a striking increase in arborization. This stimulation of oligodendrocyte growth could be replicated by low concentrations of 8-bromo-cGMP (maximum effect at 1 µM). It is concluded that oligodendrocytes are probably widespread targets for physiological NO (or natriuretic peptide) signals, with the resulting rise in cGMP serving to enhance their growth and maturation. NO might help coordinate the myelination of axons to the ongoing level of neuronal activity during development and could potentially contribute to adaptive changes in myelination in the adult. PMID:25327839

  19. Mechanism of Ad5 Vaccine Immunity and Toxicity: Fiber Shaft Targeting of Dendritic Cells

    PubMed Central

    Kong, Wing-pui; Sheets, Rebecca L; Gomez, Phillip L; King, C. Richter; Nabel, Gary J

    2007-01-01

    Recombinant adenoviral (rAd) vectors elicit potent cellular and humoral immune responses and show promise as vaccines for HIV-1, Ebola virus, tuberculosis, malaria, and other infections. These vectors are now widely used and have been generally well tolerated in vaccine and gene therapy clinical trials, with many thousands of people exposed. At the same time, dose-limiting adverse responses have been observed, including transient low-grade fevers and a prior human gene therapy fatality, after systemic high-dose recombinant adenovirus serotype 5 (rAd5) vector administration in a human gene therapy trial. The mechanism responsible for these effects is poorly understood. Here, we define the mechanism by which Ad5 targets immune cells that stimulate adaptive immunity. rAd5 tropism for dendritic cells (DCs) was independent of the coxsackievirus and adenovirus receptor (CAR), its primary receptor or the secondary integrin RGD receptor, and was mediated instead by a heparin-sensitive receptor recognized by a distinct segment of the Ad5 fiber, the shaft. rAd vectors with CAR and RGD mutations did not infect a variety of epithelial and fibroblast cell types but retained their ability to transfect several DC types and stimulated adaptive immune responses in mice. Notably, the pyrogenic response to the administration of rAd5 also localized to the shaft region, suggesting that this interaction elicits both protective immunity and vector-induced fevers. The ability of replication-defective rAd5 viruses to elicit potent immune responses is mediated by a heparin-sensitive receptor that interacts with the Ad5 fiber shaft. Mutant CAR and RGD rAd vectors target several DC and mononuclear subsets and induce both adaptive immunity and toxicity. Understanding of these interactions facilitates the development of vectors that target DCs through alternative receptors that can improve safety while retaining the immunogenicity of rAd vaccines. PMID:17319743

  20. Experimental research on the penetration of tungsten-fiber/metallic-glass matrix composite material bullet into steel target

    NASA Astrophysics Data System (ADS)

    Chen, X. W.; Chen, G.

    2012-08-01

    In the present paper, the penetration experiments of tungsten-fiber/metallic-glass matrix composite material bullets into 45# steel targets are conducted by employing H25 artillery. In which, an experimental technique of sub-caliber penetration is constructed. The quasi static and dynamic behaviours of tungsten-fiber/metallic-glass matrix composite material are also experimental investigated. The self-sharpening phenomenon of composite material is observed. Integrated with metallographic analysis, the failure modes of tungsten-fiber/metallic-glass matrix composite material are identified systemically and compared with the quasi-static and dynamic material tests. It includes four failure modes, i.e., shear fracture of tungsten fiber, brittle fracture of tungsten fiber and shear fracture of metallic glass matrix as well as melting of tungsten fiber and metallic glass matrix. Comparatively, three failure mechanisms of tungsten fiber in the bullet nose are also identified, i.e., shear fracture, splitting fracture and bending or/and buckling. Finally, the mechanism of self-sharpening behaviour of tungsten-fiber/metallic-glass matrix composite material is discussed.

  1. Fiber

    MedlinePlus

    ... broccoli, spinach, and artichokes legumes (split peas, soy, lentils, etc.) almonds Look for the fiber content of ... salsa, taco sauce, and cheese for dinner. Add lentils or whole-grain barley to your favorite soups. ...

  2. Fiber

    MedlinePlus

    ... short period of time can cause intestinal gas ( flatulence ), bloating , and abdominal cramps . This problem often goes ... 213. National Research Council. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and ...

  3. System simulation method for fiber-based homodyne multiple target interferometers using short coherence length laser sources

    NASA Astrophysics Data System (ADS)

    Fox, Maik; Beuth, Thorsten; Streck, Andreas; Stork, Wilhelm

    2015-09-01

    Homodyne laser interferometers for velocimetry are well-known optical systems used in many applications. While the detector power output signal of such a system, using a long coherence length laser and a single target, is easily modelled using the Doppler shift, scenarios with a short coherence length source, e.g. an unstabilized semiconductor laser, and multiple weak targets demand a more elaborated approach for simulation. Especially when using fiber components, the actual setup is an important factor for system performance as effects like return losses and multiple way propagation have to be taken into account. If the power received from the targets is in the same region as stray light created in the fiber setup, a complete system simulation becomes a necessity. In previous work, a phasor based signal simulation approach for interferometers based on short coherence length laser sources has been evaluated. To facilitate the use of the signal simulation, a fiber component ray tracer has since been developed that allows the creation of input files for the signal simulation environment. The software uses object oriented MATLAB code, simplifying the entry of different fiber setups and the extension of the ray tracer. Thus, a seamless way from a system description based on arbitrarily interconnected fiber components to a signal simulation for different target scenarios has been established. The ray tracer and signal simulation are being used for the evaluation of interferometer concepts incorporating delay lines to compensate for short coherence length.

  4. Comparison of adenovirus fiber, protein IX, and hexon capsomeres as scaffolds for vector purification and cell targeting

    SciTech Connect

    Campos, Samuel K.; Barry, Michael A. . E-mail: mab@bcm.edu

    2006-06-05

    The direct genetic modification of adenoviral capsid proteins with new ligands is an attractive means to confer targeted tropism to adenoviral vectors. Although several capsid proteins have been reported to tolerate the genetic fusion of foreign peptides and proteins, direct comparison of cell targeting efficiencies through the different capsomeres has been lacking. Likewise, direct comparison of with one or multiple ligands has not been performed due to a lack of capsid-compatible ligands available for retargeting. Here we utilize a panel of metabolically biotinylated Ad vectors to directly compare targeted transduction through the fiber, protein IX, and hexon capsomeres using a variety of biotinylated ligands including antibodies, transferrin, EGF, and cholera toxin B. These results clearly demonstrate that cell targeting with a variety of high affinity receptor-binding ligands is only effective when transduction is redirected through the fiber protein. In contrast, protein IX and hexon-mediated targeting by the same set of ligands failed to mediate robust vector targeting, perhaps due to aberrant trafficking at the cell surface or inside targeted cells. These data suggest that vector targeting by genetic incorporation of high affinity ligands will likely be most efficient through modification of the adenovirus fiber rather than the protein IX and hexon capsomeres. In contrast, single-step monomeric avidin affinity purification of Ad vectors using the metabolic biotinylation system is most effective through capsomeres like protein IX and hexon.

  5. Adsorption of SO2 onto oxidized and heat-treated activated carbon fibers (ACFS)

    USGS Publications Warehouse

    Daley, M.A.; Mangun, C.L.; DeBarr, J.A.; Riha, S.; Lizzio, A.A.; Donnals, G.L.; Economy, J.

    1997-01-01

    A series of activated carbon fibers (ACFs) and heat-treated oxidized ACFs prepared from phenolic fiber precursors have been studied to elucidate the role of pore size, pore surface chemistry and pore volume for the adsorption of SO2 and its catalytic conversion to H2SO4. For untreated ACFs, the initial rate of SO2 adsorption from flue gas was shown to be inversely related to pore size. At longer times, the amount of SO2 adsorbed from flue gas was dependent on both the pore size and pore volume. Oxidation of the ACFs, using an aqueous oxidant, decreased their adsorption capacity for SO2 from flue gas due to a decrease in pore volume and repulsion of the SO2 from acidic surface groups. If these samples were heat-treated to desorb the oxygen containing function groups, the amount of SO2 adsorption increased. This increase in adsorption capacity was directly correlated to the amount of CO2 evolved during heat-treatment of the oxidized ACFs. The amount of SO2 adsorbed for these samples was related to the pore size, pore surface chemistry and pore volume. This analysis is explained in more detail in this paper. ?? 1997 Elsevier Science Ltd. All rights reserved.

  6. Targeting of nitric oxide synthase to endothelial cell caveolae via palmitoylation: implications for nitric oxide signaling.

    PubMed Central

    García-Cardeña, G; Oh, P; Liu, J; Schnitzer, J E; Sessa, W C

    1996-01-01

    The membrane association of endothelial nitric oxide synthase (eNOS) plays an important role in the biosynthesis of nitric oxide (NO) in vascular endothelium. Previously, we have shown that in cultured endothelial cells and in intact blood vessels, eNOS is found primarily in the perinuclear region of the cells and in discrete regions of the plasma membrane, suggesting trafficking of the protein from the Golgi to specialized plasma membrane structures. Here, we show that eNOS is found in Triton X-100-insoluble membranes prepared from cultured bovine aortic endothelial cells and colocalizes with caveolin, a coat protein of caveolae, in cultured bovine lung microvascular endothelial cells as determined by confocal microscopy. To examine if eNOS is indeed in caveolae, we purified luminal endothelial cell plasma membranes and their caveolae directly from intact, perfused rat lungs. eNOS is found in the luminal plasma membranes and is markedly enriched in the purified caveolae. Because palmitoylation of eNOS does not significantly influence its membrane association, we next examined whether this modification can affect eNOS targeting to caveolae. Wild-type eNOS, but not the palmitoylation mutant form of the enzyme, colocalizes with caveolin on the cell surface in transfected NIH 3T3 cells, demonstrating that palmitoylation of eNOS is necessary for its targeting into caveolae. These data suggest that the subcellular targeting of eNOS to caveolae can restrict NO signaling to specific targets within a limited microenvironment at the cell surface and may influence signal transduction through caveolae. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8692835

  7. Mitochondria-Mediated Oxidative Stress: Old Target for New Drugs.

    PubMed

    Lyakhovich, Alex; Graifer, Dmitri

    2015-01-01

    Oxidative stress, one of the crucial factors of genomic instability, is involved in many illnesses - from DNA damage and repair (DDR) related diseases to neurological abnormalities and cancer. Patients with defective DDR pathways display high level of cancer predisposition and at the same time - reveal hydrocephalia, dementias and even diabetes mellitus - all representing common hallmarks of mitochondria-related disorders. Since mitochondria are responsible both for the cell energetic metabolism and for reactive oxygen/nitrogen species (RO/NS) formation, mitochondrial dysfunction (MDF) play a pivotal role in the above disorders. Not surprisingly, RO/NS are considered to be a primary target for a large spectrum of compounds aiming to eliminate these adverse species or, in contrary, enhance their presence in order to amplify cellular death pathways. Yet, only few chemicals have received medical appreciation mainly because of their questionable therapeutic values in healthy states. As a result, recent efforts have been focused on finding the drugs that improve mitochondrial functions or chemoprevent MDF rather than being applied as RO/NS scavengers. This review addresses the most recent progress in the development and application of such chemicals and outlines some future perspectives. PMID:26219394

  8. Thermo-Oxidative Stability of Graphite/PMR-15 Composites: Effect of Fiber Surface Modification on Composite Shear Properties

    NASA Technical Reports Server (NTRS)

    Madhukar, Madhu S.; Bowles, Kenneth J.; Papadopolous, Demetrios S.

    1994-01-01

    Experiments were conducted to establish a correlation between the weight loss of a polyimide (PMR- 15) matrix and graphite fibers and the in-plane shear properties of their unidirectional composites subjected to different isothermal aging times up to 1000 hr at 316 C. The role of fiber surface treatment on the composite degradation during the thermo-oxidative aging was investigated by using A4 graphite fibers with three surface modifications: untreated (AU-4), surface treated (AS-4), and surface treated and sized with an epoxy-compatible sizing (AS-4G). The weight loss of the matrix fibers, and composites was determined during the aging. The effect of thermal aging was seen in all the fiber samples in terms of weight loss and reduction in fiber diameter. Calculated values of weight loss fluxes for different surfaces of rectangular unidirectional composite plates showed that the largest weight loss occurred at those cut surfaces where fibers were perpendicular to the surface. Consequently, the largest amount of damage was also noted on these cut surfaces. Optical observation of the neat matrix and composite plates subjected to different aging times revealed that the degradation (such as matrix microcracking and void growth) occurred in a thin surface layer near the specimen edges. The in-plane shear modulus of the composites was unaffected by the fiber surface treatment and the thermal aging. The shear strength of the composites with the untreated fibers was the lowest and it decreased with aging. A fracture surface examination of the composites with untreated fibers suggested that the weak interface allowed the oxidation reaction to proceed along the interface and thus expose the inner material to further oxidation. The results indicated that the fiber-matrix interface affected the composite degradation process during its thermal aging and that the the weak interface accelerated the composite degradation.

  9. Composite polymer/oxide hollow fiber contactors: versatile and scalable flow reactors for heterogeneous catalytic reactions in organic synthesis.

    PubMed

    Moschetta, Eric G; Negretti, Solymar; Chepiga, Kathryn M; Brunelli, Nicholas A; Labreche, Ying; Feng, Yan; Rezaei, Fateme; Lively, Ryan P; Koros, William J; Davies, Huw M L; Jones, Christopher W

    2015-05-26

    Flexible composite polymer/oxide hollow fibers are used as flow reactors for heterogeneously catalyzed reactions in organic synthesis. The fiber synthesis allows for a variety of supported catalysts to be embedded in the walls of the fibers, thus leading to a diverse set of reactions that can be catalyzed in flow. Additionally, the fiber synthesis is scalable (e.g. several reactor beds containing many fibers in a module may be used) and thus they could potentially be used for the large-scale production of organic compounds. Incorporating heterogeneous catalysts in the walls of the fibers presents an alternative to a traditional packed-bed reactor and avoids large pressure drops, which is a crucial challenge when employing microreactors. PMID:25865826

  10. Oxidation kinetics of coated silicon carbide fiber-reinforced silicon carbide (SiC/SiC)

    SciTech Connect

    Fox, D.S.

    1994-12-31

    Silicon carbide fiber-reinforced silicon carbide (SiC/SiC) was exposed for 100 hours to dry, flowing oxygen. Oxidation kinetics were determined via thermogravimetric analysis at 981{degrees}, 1204{degrees} and 1316{degrees}C (1800{degrees}, 2200{degrees} and 2400{degrees}F). The effectiveness of three external coating systems applied for oxidation protection is discussed. In all cases, weight gains were observed, and the pyrolytic carbon interface layer remained intact. A CVD SiC external coating is the most promising due to low oxidation kinetics resulting from solid silica formation. A borosilicate glass was observed on the surface of two of the materials that have boron-containing coatings.

  11. Effect of atmospheric oxidative plasma treatments on polypropylenic fibers surface: Characterization and reaction mechanisms

    NASA Astrophysics Data System (ADS)

    Nisticò, Roberto; Magnacca, Giuliana; Faga, Maria Giulia; Gautier, Giovanna; D'Angelo, Domenico; Ciancio, Emanuele; Lamberti, Roberta; Martorana, Selanna

    2013-08-01

    Atmospheric pressure plasma-dielectric barrier discharge (APP-DBD, open chamber configuration) was used to functionalize polypropylene (PP) fibers surface in order to generate oxidized-reactive groups such as hydroperoxides, alcohols and carbonyl species (i.e. ketones and others). Such a species increased the surface polarity, without causing material degradation. Three different types of plasma mixture (He, He/O2, He/O2/H2O) under three different values of applied power (750, 1050, 1400 W) were investigated. The formed plasma species (O2+, O single atom and OH radical) and their distribution were monitored via optical emission spectrometry (OES) measurements, and the plasma effects on PP surface species formation were followed by X-ray photoemission spectroscopy (XPS). Results allowed to better understand the reaction pathways between plasma phase and PP fibers. In fact, two reaction mechanisms were proposed, the first one concerning the plasma phase reactions and the second one involving material surface modifications.

  12. Tunable Q-switched fiber laser using zinc oxide nanoparticles as a saturable absorber.

    PubMed

    Ahmad, H; Lee, C S J; Ismail, M A; Ali, Z A; Reduan, S A; Ruslan, N E; Harun, S W

    2016-06-01

    Nanomaterials have ignited new interest due to their distinctive electronic, mechanical, and optical properties. Zinc oxide nanostructures are fabricated into thin film and then inserted between two fiber ferrules to act as a saturable absorber (SA). The modulation depth and insertion loss of the SA are 5% and 3.5 dB, respectively. When the ZnO-SA is incorporated into the laser cavity, a stable Q-switched pulse tunable from 1536 to 1586 nm (50 nm range) with pulse energy up to 46 nJ was observed. Our result suggests that ZnO is a promising broadband SA to generate passively Q-switched fiber lasers. PMID:27411175

  13. Parallel expression evolution of oxidative stress-related genes in fiber from wild and domesticated diploid and polyploid cotton (Gossypium)

    PubMed Central

    2009-01-01

    Background Reactive oxygen species (ROS) play a prominent role in signal transduction and cellular homeostasis in plants. However, imbalances between generation and elimination of ROS can give rise to oxidative stress in growing cells. Because ROS are important to cell growth, ROS modulation could be responsive to natural or human-mediated selection pressure in plants. To study the evolution of oxidative stress related genes in a single plant cell, we conducted comparative expression profiling analyses of the elongated seed trichomes ("fibers") of cotton (Gossypium), using a phylogenetic approach. Results We measured expression changes during diploid progenitor species divergence, allopolyploid formation and parallel domestication of diploid and allopolyploid species, using a microarray platform that interrogates 42,429 unigenes. The distribution of differentially expressed genes in progenitor diploid species revealed significant up-regulation of ROS scavenging and potential signaling processes in domesticated G. arboreum. Similarly, in two independently domesticated allopolyploid species (G. barbadense and G. hirsutum) antioxidant genes were substantially up-regulated in comparison to antecedent wild forms. In contrast, analyses of three wild allopolyploid species indicate that genomic merger and ancient allopolyploid formation had no significant influences on regulation of ROS related genes. Remarkably, many of the ROS-related processes diagnosed as possible targets of selection were shared among diploid and allopolyploid cultigens, but involved different sets of antioxidant genes. Conclusion Our data suggests that parallel human selection for enhanced fiber growth in several geographically widely dispersed species of domesticated cotton resulted in similar and overlapping metabolic transformations of the manner in which cellular redox levels have become modulated. PMID:19686594

  14. Functional pools of oxidative and glycolytic fibers in human muscle observed by /sup 31/P magnetic resonance spectroscopy during exercise

    SciTech Connect

    Park, J.H.; Brown, R.L.; Park, C.R.; McCully, K.; Cohn, M.; Haselgrove, J.; Chance, B.

    1987-12-01

    Quantitative probing of heterogeneous regions in muscle is feasible with phosphorus-31 magnetic resonance spectroscopy because of the differentiation of metabolic patterns of glycolytic and oxidative fibers. A differential recruitment of oxidative and glycolytic fibers during exercise was demonstrated in 4 of 10 untrained young men by following changes in phosphate metabolites. Concentrations of inorganic phosphate (P/sub i/), phosphocreatine, and ATP were estimated in the wrist flexor muscles of the forearm at rest, during two cycles of three grades of exercise, and in recovery. At high work levels (40% of maximum strength), two distinct P/sub i/ peaks were observed and identified with P/sub i/ pools at pH 6.9 and pH 5.9-6.4, respectively. These could be accounted for as follows. At the lowest level of work (using 20% of maximum strength), early recruitment primarily of oxidative (type I) and possibly some intermediate (type IIA) muscle fibers occurs with relatively little net lactate production and consequently little decrease in pH. At higher work loads, however, primarily glycolytic (type IIB) muscle fibers are recruited, which have relatively high net lactate production and therefore generate a second pool of P/sub i/ at low pH. These observations indicated exhaustion of glycolytic type IIB fibers, removal of lactate by high local blood flow, and sustained contractions largely by oxidative type I and IIA fibers. A functional differentiation of fiber types could also be demonstrated during recovery if exercise was stopped while two pools of P/sub i/ were still apparent. The potential of magnetic resonance spectroscopy to characterize oxidative and glycolytic fibers, predict capacity for aerobic performance, and signal the presence of muscle pathology is discussed.

  15. Oxidation-resistant interfacial coatings for fiber-reinforced ceramic composites

    SciTech Connect

    Lara-Curzio, Edgar; More, Karren L.; Lee, Woo Y.

    1999-04-22

    A ceramic-matrix composite having a multilayered interfacial coating adapted to protect the reinforcing fibers from long-term oxidation, while allowing these to bridge the wake of advancing cracks in the matrix, is provided by selectively mismatching materials within adjacent layers of the interfacial coating, the materials having different coefficients of thermal expansion so that a low toughness interface region is created to promote crack deflection either within an interior layer of the mismatched interfacial coating or between adjacent layers of the mismatched interfacial coating.

  16. Fermentable dietary fibers elevate urinary methylmalonate and decrease propionate oxidation in rats deprived of vitamin B-12.

    PubMed

    Cullen, R W; Oace, S M

    1989-08-01

    This study examines the effect of dietary fiber supplements of different degrees of bacterial fermentability on biochemical indicators of vitamin B-12 deficiency in rats. Groups of rats were fed a fiber-free diet deficient in vitamin B-12 or the fiber-free diet diluted with 5% of a poorly fermentable dietary fiber (cellulose, lignin or alginic acid) or a highly fermentable fiber (pectin, guar gum or xylan). Poorly fermentable fibers had no significant effect on apparent B-12 status, whereas the highly fermentable fibers significantly increased urinary methylmalonic acid and depressed oxidation of [14C]propionate to 14CO2. Pectin consistently induced significantly greater effects than did xylan or guar gum. The data are consistent with the hypothesis that fermentable fibers stimulate bacterial propionate production and exaggerate certain biochemical indicators of B-12 deficiency. Since pectin had a more pronounced effect than did other fermentable fibers, the possibility that pectin may also interfere with B-12 absorption requires further study. PMID:2550598

  17. Graphite Sheet Coating for Improved Thermal Oxidative Stability of Carbon Fiber Reinforced/PMR-15 Composites

    NASA Technical Reports Server (NTRS)

    Campbell, Sandi; Papadopoulos, Demetrios; Heimann, Paula; Inghram, Linda; McCorkle, Linda

    2005-01-01

    Expanded graphite was compressed into graphite sheets and used as a coating for carbon fiber reinforced PMR-15 composites. BET analysis of the graphite indicated an increase in graphite pore size on compression, however the material was proven to be an effective barrier to oxygen when prepegged with PMR-15 resin. Oxygen permeability of the PMR-15/graphite was an order of magnitude lower than the compressed graphite sheet. By providing a barrier to oxygen permeation, the rate of oxidative degradation of PMR-15 was decreased. As a result, the composite thermo-oxidative stability increased by up to 25%. The addition of a graphite sheet as a top ply on the composites yielded little change in the material's flexural strength or interlaminar shear strength.

  18. Fiber optic humidity sensor based on the graphene oxide/PVA composite film

    NASA Astrophysics Data System (ADS)

    Wang, Youqing; Shen, Changyu; Lou, Weimin; Shentu, Fengying

    2016-08-01

    Fiber optic humidity sensor based on an in-fiber Mach-Zehnder interferometer (MZI) coated with graphene oxide (GO)/PVA composite film was investigated. The MZI is constructed of two waist-enlarged tapers. The length between two waist-enlarged tapers is 20 mm. By comparing the experiment results of MZI coated with different GO/PVA composite films, composite film formed by the ratio of 0.3 g PVA mixed with 10 ml GO dispersion shows a better performance of relative humidity sensing. By using the molecular structure model of the composited GO/PVA, the operation mechanism between GO/PVA composite film and water molecules was illustrated. The sensitivity of 0.193 dB/%RH with a linear correlation coefficient of 99.1% and good stability under the relative humidity range of 25-80% was obtained. Temperature effect on the proposed fiber optic humidity sensor was also considered and analyzed. According to the repetitive experimental results, the proposed humidity sensor shows a good repeatability.

  19. Immobilization of pectinase on oxidized pulp fiber and its application in whitewater treatment.

    PubMed

    Wu, Rina; He, Bei-Hai; Zhao, Guang-Lei; Qian, Li-Ying; Li, Xiao-Feng

    2013-09-12

    Modified pulp fiber was originally used as a new type of carrier for pectinase immobilization. Pulp fiber was oxidized by sodium periodate to produce aldehyde groups for covalently binding with amino groups of pectinase. Results showed that the enzymatic activity of immobilized pectinase on pulp fiber reached 65 μgg(-1)min(-1) when immobilization pH value, temperature and time were of 7.0, 20 °C and 15 min, respectively. The immobilized pectinase showed higher thermo stability in a wider temperature range of 40-70 °C than its free type and its optimal pH shifted from 8.0 to 8.8. Furthermore, the immobilized pectinase exhibited good operational stability. When employed in whitewater treatment of papermaking industry, it still efficiently decreased the cationic demand after operating repeatedly for six batches. The results obtained demonstrate a promising route to prepare available, cheap and biodegradable carrier for immobilizing enzymes with potential application in wastewater treatment in papermaking industry. PMID:23911480

  20. From beads-to-wires-to-fibers of tungsten oxide: electrochromic response

    NASA Astrophysics Data System (ADS)

    Kadam, P. M.; Tarwal, N. L.; Shinde, P. S.; Patil, R. S.; Deshmukh, H. P.; Patil, P. S.

    2009-11-01

    Suitable host lattice and morphology for easy intercalation and deintercalation process are crucial requirements for electrochromic device. In this investigation, the evolution of structural and morphological changes and their effect on electrochromic (EC) properties of spray-deposited WO3 thin films are studied. Films of different morphologies were deposited from an ammonium tungstate precursor solution using a novel pulsed spray pyrolysis technique (PSPT) on tin-doped indium oxide (ITO) coated glass substrates by varying quantity of spraying solution. Interesting morphological transition from beads-to-wires-to-fibers as a function of quantity of sprayed solution has been demonstrated. The porosity, crystallinity and “open” structures in the films consisting of beads, wires, and fiber-like morphology enabled us to correlate these aspects to their EC performance. WO3 films comprising wire-like morphology (20 cc spraying quantity) exhibited better EC properties both in terms of coloration efficiency (42.7 cm2/C) and electrochemical stability (103 colored/bleached cycles) owing to their adequate open structure, porosity, and amorphicity, compared with the films having bead/fiber-like morphology.

  1. Titanium-Dioxide Nano-Fiber-Cotton Targets for Efficient Multi-keV X-Ray Generation

    SciTech Connect

    Tanabe, M; Nishimura, H; Fujioka, S; Nagai, K; Yamamoto, N; Gu, Z; Pan, C; Girard, F; Primout, M; Villette, B; Brebion, D; Fournier, K B; Fujishima, A; Mima, K

    2008-06-12

    Multi-keV x-ray generation from low-density (27 {+-} 7 mg/cc) nano-fiber-cotton targets composed of titanium-dioxide has been investigated. The cotton targets were heated volumetrically and supersonically to a peak electron temperature of 2.3 keV, which is optimal to yield Ti K-shell x rays. Considerable enhancement of conversion efficiency (3.7 {+-} 0.5%) from incident laser energy into Ti K-shell x rays (4-6 keV band) was attained in comparison with that (1.4 {+-} 0.9%) for a planar Ti-foil target.

  2. Sol-gel nanocasting synthesis of patterned hierarchical LaFeO3 fibers with enhanced catalytic CO oxidation activity.

    PubMed

    Li, Pengna; Hu, Xianluo; Zhang, Lei; Dai, Hongxing; Zhang, Lizhi

    2011-03-01

    Hierarchical LaFeO3 fibers were prepared by a sol-gel nanocasting method using a cotton cloth as the template. The resulting LaFeO3 fibers inherited the initial network morphology of the template very well and showed enhanced catalytic CO oxidation activity and satisfactory stability compared to the counterpart particles prepared by the conventional sol-gel method. PMID:21234504

  3. Fabrication and application of zinc-zinc oxide nanosheets coating on an etched stainless steel wire as a selective solid-phase microextraction fiber.

    PubMed

    Song, Wenlan; Guo, Mei; Zhang, Yida; Zhang, Min; Wang, Xuemei; Du, Xinzhen

    2015-03-01

    A novel zinc-zinc oxide (Zn-ZnO) nanosheets coating was directly fabricated on an etched stainless steel wire substrate as solid-phase microextraction (SPME) fiber via previous electrodeposition of robust Zn coating. The scanning electron micrograph of the Zn-ZnO nanosheets coated fiber exhibits a flower-like nanostructure with high surface area. The SPME performance of as-fabricated fiber was investigated for the concentration and determination of polycyclic aromatic hydrocarbons, phthalates and ultraviolet (UV) filters coupled to high performance liquid chromatography with UV detection (HPLC-UV). It was found that the Zn-ZnO nanosheets coating exhibited high extraction capability, good selectivity and rapid mass transfer for some UV filters. The main parameters affecting extraction performance were investigated and optimized. Under the optimized conditions, the calibration graphs were linear over the range of 0.1-200μgL(-1). The limits of detection of the proposed method were 0.052-0.084μgL(-1) (S/N=3). The single fiber repeatability varied from 5.18% to 7.56% and the fiber-to-fiber reproducibility ranged from 6.74% to 8.83% for the extraction of spiked water with 50μgL(-1) UV filters (n=5). The established SPME-HPLC-UV method was successfully applied to the selective concentration and sensitive determination of target UV filters from real environmental water samples with recoveries from 85.8% to 105% at the spiking level of 10μgL(-1) and 30μgL(-1). The relative standard deviations were below 9.7%. PMID:25662065

  4. In situ synthesis of manganese oxides on polyester fiber for formaldehyde decomposition at room temperature

    NASA Astrophysics Data System (ADS)

    Wang, Jinlong; Yunus, Rizwangul; Li, Jinge; Li, Peilin; Zhang, Pengyi; Kim, Jeonghyun

    2015-12-01

    Removal of low-level formaldehyde (HCHO) is of great interest for indoor air quality improvement. Supported materials especially those with low air pressure drop are of necessity for air purification. Manganese oxides (MnOx) was in situ deposited on the surface of fibers of a non-woven fabric made of polyethylene terephthalate (PET). As-synthesized MnOx/PET were characterized by SEM, XRD, TEM, ATR-FTIR and XPS analysis. The growth of MnOx layer on PET is thought to start with partial hydrolysis of PET, followed by surface oxidation by KMnO4 and then surface-deposition of MnOx particles from the bulk phase. The MnOx particles assembled with nanosheets were uniformly coated on the PET fibers. MnOx/PET showed good activity for HCHO decomposition at room temperature which followed the Mars-van Krevelen mechanism. The removal of HCHO was kept over 94% after 10 h continuous reaction under the conditions of inlet HCHO concentration ∼0.6 mg/m3, space velocity ∼17,000 h-1 and relative humidity∼50%. This research provides a facile method to deposit active MnOx onto polymers with low air resistance, and composite MnOx/PET material is promising for indoor air purification.

  5. Reduced graphene oxide coated optical fiber for methanol and ethanol vapor detection at room temperature

    NASA Astrophysics Data System (ADS)

    Kavinkumar, T.; Sastikumar, D.; Manivannan, S.

    2014-10-01

    Successful isolation of single layer of graphene from graphite by mechanical exfoliation method, attracted a great attention due to its unique structural, optical, mechanical and electronic properties. This makes the graphene as a promising material in many possible applications such as energy-storage, sensing, electronic, optical devices and polymer composite materials. High quality of reduced graphene oxide (rGO) material was prepared by chemical reduction method at 100°C. The structural and optical properties of the rGO sheets were characterized by FT-IR, micro Raman, powder XRD and UV-vis-NIR techniques. FT-IR reveals the absence of oxygen functional groups on rGO due to the reduction process. Powder XRD shows the broad peak at 2θ=24.3° corresponding to interlayer spacing 3.66Å which is smaller than the graphene oxide (GO). UV-vis-NIR of rGO displays the absorption peak at 271 nm indicates the reduction of GO and the restoration of C=C bonds in the rGO sheets. The cladding removed and rGO coated poly-methyl methacrylate (PMMA) optical fiber is used for methanol and ethanol vapors detection in the concentration ranging from 0 to 500 ppm at room temperature. The spectral characteristics along with output intensity modulation of cladding removed and rGO coated fiber optic sensor reveal the potential of methanol and ethanol vapor sensing properties.

  6. Cytotoxicity, oxidative stress and genotoxicity induced by glass fibers on human alveolar epithelial cell line A549.

    PubMed

    Rapisarda, Venerando; Loreto, Carla; Ledda, Caterina; Musumeci, Giuseppe; Bracci, Massimo; Santarelli, Lory; Renis, Marcella; Ferrante, Margherita; Cardile, Venera

    2015-04-01

    Man-made vitreous fibers have been widely used as insulation material as asbestos substitutes; however their morphology and composition raises concerns. In 1988 the International Agency for Research on Cancer classified fiberglass, rock wool, slag wool, and ceramic fibers as Group 2B, i.e. possibly carcinogenic to humans. In 2002 it reassigned fiberglass, rock and slag wool, and continuous glass filaments to Group 3, not classifiable as carcinogenic to humans. The aim of this study was to verify the cytotoxic and genotoxic effects and oxidative stress production induced by in vitro exposure of human alveolar epithelial cells A549 to glass fibers with a predominant diameter <3 μm (97%) and length >5 μm (93%). A549 cells were incubated with 5, 50, or 100 μg/ml (2.1, 21, and 42 μg/cm(2), respectively) of glass fibers for 72 h. Cytotoxicity and DNA damage were tested by the MTT and the Comet assay, respectively. Oxidative stress was determined by measuring inducible nitric oxide synthase (iNOS) expression by Western blotting, production of nitric oxide (NO) with Griess reagent, and concentration of reactive oxygen species by fluorescent quantitative analysis with 2',7'-dichlorofluorescein-diacetate (DCFH-DA). The results showed that glass fiber exposure significantly reduced cell viability and increased DNA damage and oxidative stress production in a concentration-dependent manner, demonstrating that glass fibers exert cytotoxic and genotoxic effects related to increased oxidative stress on the human alveolar cell line A549. PMID:25620604

  7. Fiber optic coupled optical sensor

    DOEpatents

    Fleming, Kevin J.

    2001-01-01

    A displacement sensor includes a first optical fiber for radiating light to a target, and a second optical fiber for receiving light from the target. The end of the first fiber is adjacent and not axially aligned with the second fiber end. A lens focuses light from the first fiber onto the target and light from the target onto the second fiber.

  8. Functional pools of oxidative and glycolytic fibers in human muscle observed by 31P magnetic resonance spectroscopy during exercise.

    PubMed

    Park, J H; Brown, R L; Park, C R; McCully, K; Cohn, M; Haselgrove, J; Chance, B

    1987-12-01

    Quantitative probing of heterogeneous regions in muscle is feasible with phosphorus-31 magnetic resonance spectroscopy because of the differentiation of metabolic patterns of glycolytic and oxidative fibers. A differential recruitment of oxidative and glycolytic fibers during exercise was demonstrated in 4 of 10 untrained young men by following changes in phosphate metabolites. Concentrations of inorganic phosphate (Pi), phosphocreatine, and ATP were estimated in the wrist flexor muscles of the forearm at rest, during two cycles of three grades of exercise, and in recovery. At high work levels (40% of maximum strength), two distinct Pi peaks were observed and identified with Pi pools at pH 6.9 and pH 5.9-6.4, respectively. These could be accounted for as follows. At the lowest level of work (using 20% of maximum strength), early recruitment primarily of oxidative (type I) and possibly some intermediate (type IIA) muscle fibers occurs with relatively little net lactate production and consequently little decrease in pH. At higher work loads, however, primarily glycolytic (type IIB) muscle fibers are recruited, which have relatively high net lactate production and therefore generate a second pool of Pi at low pH. ATP depletion (35-54%) and Pi losses accompanied the reduction in ability to perform during the first exercise cycle. When the cycle of graded exercise was repeated immediately, the total Pi remained high but gave rise to only one peak at pH 6.8-7.0. These observations indicated exhaustion of glycolytic type IIB fibers, removal of lactate by high local blood flow, and sustained contractions largely by oxidative type I and IIA fibers. A functional differentiation of fiber types could also be demonstrated during recovery if exercise was stopped while two pools of Pi were still apparent. In the first 3 min of recovery, the Pi peak at pH 6.8-6.9 disappeared almost entirely, whereas the Pi peak at pH 6.0 remained unaltered, reflecting the faster recovery of

  9. Nitric oxide synthase inhibition and oxidative stress in cardiovascular diseases: possible therapeutic targets?

    PubMed

    Rochette, Luc; Lorin, Julie; Zeller, Marianne; Guilland, Jean-Claude; Lorgis, Luc; Cottin, Yves; Vergely, Catherine

    2013-12-01

    Nitric oxide (NO) is synthetized enzymatically from l-arginine (l-Arg) by three NO synthase isoforms, iNOS, eNOS and nNOS. The synthesis of NO is selectively inhibited by guanidino-substituted analogs of l-Arg or methylarginines such as asymmetric dimethylarginine (ADMA), which results from protein degradation in cells. Many disease states, including cardiovascular diseases and diabetes, are associated with increased plasma levels of ADMA. The N-terminal catalytic domain of these NOS isoforms binds the heme prosthetic group as well as the redox cofactor, tetrahydrobiopterin (BH(4)) associated with a regulatory protein, calmodulin (CaM). The enzymatic activity of NOS depends on substrate and cofactor availability. The importance of BH(4) as a critical regulator of eNOS function suggests that BH(4) may be a rational therapeutic target in vascular disease states. BH(4) oxidation appears to be a major contributor to vascular dysfunction associated with hypertension, ischemia/reperfusion injury, diabetes and other cardiovascular diseases as it leads to the increased formation of oxygen-derived radicals due to NOS uncoupling rather than NO. Accordingly, abnormalities in vascular NO production and transport result in endothelial dysfunction leading to various cardiovascular disorders. However, some disorders including a wide range of functions in the neuronal, immune and cardiovascular system were associated with the over-production of NO. Inhibition of the enzyme should be a useful approach to treat these pathologies. Therefore, it appears that both a lack and excess of NO production in diseases can have various important pathological implications. In this context, NOS modulators (exogenous and endogenous) and their therapeutic effects are discussed. PMID:23859953

  10. Targeted iron oxide nanoparticles for the enhancement of radiation therapy.

    PubMed

    Hauser, Anastasia K; Mitov, Mihail I; Daley, Emily F; McGarry, Ronald C; Anderson, Kimberly W; Hilt, J Zach

    2016-10-01

    To increase the efficacy of radiation, iron oxide nanoparticles can be utilized for their ability to produce reactive oxygen species (ROS). Radiation therapy promotes leakage of electrons from the electron transport chain and leads to an increase in mitochondrial production of the superoxide anion which is converted to hydrogen peroxide by superoxide dismutase. Iron oxide nanoparticles can then catalyze the reaction from hydrogen peroxide to the highly reactive hydroxyl radical. Therefore, the overall aim of this project was to utilize iron oxide nanoparticles conjugated to a cell penetrating peptide, TAT, to escape lysosomal encapsulation after internalization by cancer cells and catalyze hydroxyl radical formation. It was determined that TAT functionalized iron oxide nanoparticles and uncoated iron oxide nanoparticles resulted in permeabilization of the lysosomal membranes. Additionally, mitochondrial integrity was compromised when A549 cells were treated with both TAT-functionalized nanoparticles and radiation. Pre-treatment with TAT-functionalized nanoparticles also significantly increased the ROS generation associated with radiation. A long term viability study showed that TAT-functionalized nanoparticles combined with radiation resulted in a synergistic combination treatment. This is likely due to the TAT-functionalized nanoparticles sensitizing the cells to subsequent radiation therapy, because the nanoparticles alone did not result in significant toxicities. PMID:27521615

  11. A monitor and control system for high voltage, gating, and triggering of a scintillating fiber active target

    SciTech Connect

    Baumbaugh, B.; Bishop, J.; Gardner, R.W.; Mountain, R.J.; Ruchti, R.; Baumbaugh, A.; Knickerbocker, K.

    1988-02-01

    A monitor and control system has been designed, constructed and tested at Notre Dame for the purpose of controlling all aspects of a Scintillating Fiber Acxtive Target system used in High Energy Physics Experimentation. The SFT Active Target system requires control of high voltages, gating, trigger counters, and monitoring. In addition, it resides in a radioactive area with very limited access. The control system uses a Leading Edge microcomputer, two specialized Z80-based processors, associated DACs, ADCs, discrete semiconductors, linear ICs and TTL and MECL logic. All of the hardware and software is custom-built; its design and performance is discussed.

  12. A monitor and control system for high voltage, gating, and triggering of a scintillating fiber active target

    SciTech Connect

    Baumbaugh, B.; Bishop, J.; Gardner, R.W.; Mountain, R.J.; Ruchti, R.; Baumbaugh, A.; Knickerbocker, K.

    1987-10-01

    A monitor and control system has been designed, constructed and tested at Notre Dame for the purpose of controlling all aspects of a Scintillating Fiber Active Target system used in High Energy Physics Experimentation. The SFT Active Target system requires control of high voltages, gating, trigger counters, and monitoring. In addition, it resides in a radioactive area with very limited access. The control system uses a Leading Edge microcomputer, two specialized Z80-based processors, associated DACs, ADCs, discrete semiconductors, linear ICs, and TTL and MECL logic. All of the hardware and software is custom-built; its design and performance is discussed. 5 refs., 4 figs.

  13. Product characteristics from the torrefaction of oil palm fiber pellets in inert and oxidative atmospheres.

    PubMed

    Chen, Wei-Hsin; Zhuang, Yi-Qing; Liu, Shih-Hsien; Juang, Tarng-Tzuen; Tsai, Chi-Ming

    2016-01-01

    The aim of this work was to study the characteristics of solid and liquid products from the torrefaction of oil palm fiber pellets (OPFP) in inert and oxidative environments. The torrefaction temperature and O2 concentration in the carrier gas were in the ranges of 275-350°C and 0-10 vol%, respectively, while the torrefaction duration was 30 min. The oxidative torrefaction of OPFP at 275°C drastically intensified the HHV of the biomass when compared to the non-oxidative torrefaction. OPFP torrefied at 300°C is recommended to upgrade the biomass, irrespective of the atmosphere. The HHV of condensed liquid was between 10.1 and 13.2 MJ kg(-)(1), and was promoted to 23.2-28.7 MJ kg(-)(1) following dewatering. This accounts for 92-139% improvement in the calorific value of the liquid. This reveals that the recovery of condensed liquid with dewatering is able to enhance the energy efficiency of a torrefaction system. PMID:26346262

  14. Nickel oxide and molybdenum oxide thin films for infrared imaging prepared by biased target ion-beam deposition

    NASA Astrophysics Data System (ADS)

    Jin, Yao; Saint John, David; Jackson, Tom N.; Horn, Mark W.

    2014-06-01

    Vanadium oxide (VOx) thin films have been intensively used as sensing materials for microbolometers. VOx thin films have good bolometric properties such as low resistivity, high negative temperature coefficient of resistivity (TCR) and low 1/f noise. However, the processing controllability of VOx fabrication is difficult due to the multiple valence states of vanadium. In this study, metal oxides such as nickel oxide (NiOx) and molybdenum oxide (MoOx) thin films have been investigated as possible new microbolometer sensing materials with improved process controllability. Nickel oxide and molybdenum oxide thin films were prepared by reactive sputtering of nickel and molybdenum metal targets in a biased target ion beam deposition tool. In this deposition system, the Ar+ ion energy (typically lower than 25 eV) and the target bias voltage can be independently controlled since ions are remotely generated. A residual gas analyzer (RGA) is used to precisely control the oxygen partial pressure. A real-time spectroscopic ellipsometry is used to monitor the evolution of microstructure and properties of deposited oxides during growth and post-deposition. The properties of deposited oxide thin films depend on processing parameters. The resistivity of the NiOx thin films is in the range of 0.5 to approximately 100 ohm-cm with a TCR from -2%/K to -3.3%/K, where the resistivity of MoOx is between 3 and 2000 ohm-cm with TCR from -2.1%/K to -3.2%/K. We also report on the thermal stability of these deposited oxide thin films.

  15. Oxidation of alloys targeted for advanced steam turbines

    SciTech Connect

    Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.; Ziomek-Moroz, M.; Alman, D.E.

    2006-03-12

    Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of alloys for use in USC systems, with emphasis placed on applications in high- and intermediate-pressure turbines.

  16. Oxidative Stress and Response to Thymidylate Synthase-Targeted Antimetabolites.

    PubMed

    Ozer, Ufuk; Barbour, Karen W; Clinton, Sarah A; Berger, Franklin G

    2015-12-01

    Thymidylate synthase (TYMS; EC 2.1.1.15) catalyzes the reductive methylation of 2'-deoxyuridine-5'-monophosphate (dUMP) by N(5),N(10)-methyhlenetetrahydrofolate, forming dTMP for the maintenance of DNA replication and repair. Inhibitors of TYMS have been widely used in the treatment of neoplastic disease. A number of fluoropyrimidine and folate analogs have been developed that lead to inhibition of the enzyme, resulting in dTMP deficiency and cell death. In the current study, we have examined the role of oxidative stress in response to TYMS inhibitors. We observed that intracellular reactive oxygen species (ROS) concentrations are induced by these inhibitors and promote apoptosis. Activation of the enzyme NADPH oxidase (NOX), which catalyzes one-electron reduction of O2 to generate superoxide (O2 (●-)), is a significant source of increased ROS levels in drug-treated cells. However, gene expression profiling revealed a number of other redox-related genes that may contribute to ROS generation. TYMS inhibitors also induce a protective response, including activation of the transcription factor nuclear factor E2-related factor 2 (NRF2), a critical mediator of defense against oxidative and electrophilic stress. Our results show that exposure to TYMS inhibitors induces oxidative stress that leads to cell death, while simultaneously generating a protective response that may underlie resistance against such death. PMID:26443810

  17. Fiber-based Coherent Lidar for Target Ranging, Velocimetry, and Atmospheric Wind Sensing

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Pierrottet, Diego

    2006-01-01

    By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing state-of-the-art fiber optic technologies, highly efficient, compact and reliable lidar suitable for operation in a space environment is being developed.

  18. Metabolomics reveals that carnitine palmitoyltransferase-1 is a novel target for oxidative inactivation in human cells.

    PubMed

    Setoyama, Daiki; Fujimura, Yoshinori; Miura, Daisuke

    2013-12-01

    Oxidative dysfunction in the metabolism has long been implicated in diverse biological disorders. Although a substantial number of metabolic enzymes are targeted for inactivation by oxidative stress, identifying those targets remains difficult due to a lack of comprehensive observations of the metabolism acting through the stress response. We herein developed a metabolomics strategy using integrative liquid chromatography-mass spectrometry (LC-MS) and observing rapid metabolomic changes in response to hydrogen peroxide (H2 O2 )-induced oxidative stress in HeLa cells. Among the many metabolite changes detected, the most characteristic metabolites uniquely indicated carnitine palmitoyltransferase-1 (CPT1), the critical enzyme for mitochondrial β-oxidation of long-chain fatty acids, to be a target for oxidative inactivation. We showed that the enzymatic activity of CPT1 significantly declined by H2 O2 in several human cells. Interestingly, the inactivation was shown to be a direct effect of H2 O2 in vitro, but substantially occurred when cells were cultured with some reagents that generate reactive oxygen species (ROS). Thus, our results suggest the generality of CPT1 inhibition under various stress conditions associated with ROS generation, providing an insight into a mechanism for oxidative dysfunction in mitochondrial metabolism. Our metabolome data additionally suggest that certain methyltransferase(s) may be targets of oxidative stress as well. PMID:24118240

  19. Oxidation of SiC Fiber-Reinforced SiC Matrix Composites with a BN Interphase

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth; Boyd, Meredith K.

    2010-01-01

    SiC-fiber reinforced SiC matrix composites with a BN interphase were oxidized in reduced oxygen partial pressures of oxygen to simulate the environment for hypersonic vehicle leading edge applications. The constituent fibers as well as composite coupons were oxidized in oxygen partial pressures ranging from 1000 ppm O2 to 5% O2 balance argon. Exposure temperatures ranged from 816 C to 1353 C (1500 F to 2450 F). The oxidation kinetics of the coated fibers were monitored by thermogravimetric analysis (TGA). An initial rapid transient weight gain was observed followed by parabolic kinetics. Possible mechanisms for the transient oxidation are discussed. One edge of the composite coupon seal coat was ground off to simulate damage to the composite which allowed oxygen ingress to the interior of the composite. Oxidation kinetics of the coupons were characterized by scanning electron microscopy since the weight changes were minimal. It was found that sealing of the coupon edge by silica formation occurred. Differences in the amount and morphology of the sealing silica as a function of time, temperature and oxygen partial pressure are discussed. Implications for use of these materials for hypersonic vehicle leading edge materials are summarized.

  20. Atheroprotective Effect of Oleoylethanolamide (OEA) Targeting Oxidized LDL

    PubMed Central

    Wu, Huijuan; Li, Long; Huang, Rui; Zhu, Yueyong; Qiu, Yan; Fu, Jin; Ren, Jie; Zhu, Chenggang

    2014-01-01

    Dietary fat-derived lipid oleoylethanolamide (OEA) has shown to modulate lipid metabolism through a peroxisome proliferator-activated receptor-alpha (PPAR-α)-mediated mechanism. In our study, we further demonstrated that OEA, as an atheroprotective agent, modulated the atherosclerotic plaques development. In vitro studies showed that OEA antagonized oxidized LDL (ox-LDL)-induced vascular endothelial cell proliferation and vascular smooth muscle cell migration, and suppressed lipopolysaccharide (LPS)-induced LDL modification and inflammation. In vivo studies, atherosclerosis animals were established using balloon-aortic denudation (BAD) rats and ApoE-/- mice fed with high-caloric diet (HCD) for 17 or 14 weeks respectively, and atherosclerotic plaques were evaluated by oil red staining. The administration of OEA (5 mg/kg/day, intraperitoneal injection, i.p.) prevented or attenuated the formation of atherosclerotic plaques in HCD-BAD rats or HCD-ApoE−/− mice. Gene expression analysis of vessel tissues from these animals showed that OEA induced the mRNA expressions of PPAR-α and downregulated the expression of M-CFS, an atherosclerotic marker, and genes involved in oxidation and inflammation, including iNOS, COX-2, TNF-α and IL-6. Collectively, our results suggested that OEA exerted a pharmacological effect on modulating atherosclerotic plaque formation through the inhibition of LDL modification in vascular system and therefore be a potential candidate for anti-atherosclerosis drug. PMID:24465540

  1. Atheroprotective effect of oleoylethanolamide (OEA) targeting oxidized LDL.

    PubMed

    Fan, Angran; Wu, Xiaofeng; Wu, Huijuan; Li, Long; Huang, Rui; Zhu, Yueyong; Qiu, Yan; Fu, Jin; Ren, Jie; Zhu, Chenggang

    2014-01-01

    Dietary fat-derived lipid oleoylethanolamide (OEA) has shown to modulate lipid metabolism through a peroxisome proliferator-activated receptor-alpha (PPAR-α)-mediated mechanism. In our study, we further demonstrated that OEA, as an atheroprotective agent, modulated the atherosclerotic plaques development. In vitro studies showed that OEA antagonized oxidized LDL (ox-LDL)-induced vascular endothelial cell proliferation and vascular smooth muscle cell migration, and suppressed lipopolysaccharide (LPS)-induced LDL modification and inflammation. In vivo studies, atherosclerosis animals were established using balloon-aortic denudation (BAD) rats and ApoE(-/-) mice fed with high-caloric diet (HCD) for 17 or 14 weeks respectively, and atherosclerotic plaques were evaluated by oil red staining. The administration of OEA (5 mg/kg/day, intraperitoneal injection, i.p.) prevented or attenuated the formation of atherosclerotic plaques in HCD-BAD rats or HCD-ApoE(-/-) mice. Gene expression analysis of vessel tissues from these animals showed that OEA induced the mRNA expressions of PPAR-α and downregulated the expression of M-CFS, an atherosclerotic marker, and genes involved in oxidation and inflammation, including iNOS, COX-2, TNF-α and IL-6. Collectively, our results suggested that OEA exerted a pharmacological effect on modulating atherosclerotic plaque formation through the inhibition of LDL modification in vascular system and therefore be a potential candidate for anti-atherosclerosis drug. PMID:24465540

  2. Double layer oxidation resistant coating for carbon fiber reinforced silicon carbide matrix composites

    NASA Astrophysics Data System (ADS)

    Zheng, X. H.; Du, Y. G.; Xiao, J. Y.; Zhang, W. J.; Zhang, L. C.

    2009-01-01

    Double layer coatings, with celsian-Y 2SiO 5 as inner layer and Y 2Si 2O 7 as outer layer, were prepared by microwave sintering on the surface of carbon fiber reinforced silicon carbide matrix composite. Both celsian, Y 2SiO 5 and Y 2Si 2O 7 were synthesized by in situ method using BAS glass, Y 2O 3 and SiO 2 as staring materials. The sintering temperature was 1500 °C, and little damage was induced to the composite. The composition and micrograph of the fired coating were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The oxidation and thermal shock resistance of samples with doubled-layered coating were characterized at 1400 °C in air. After 150 min oxidation and thermal cycling between 1400 °C and room temperature for 15 times, the weight loss of double layer-coated sample was 1.22% and there were no cracks in the coating.

  3. A comparative study of carbon fiber-based microelectrodes for the measurement of nitric oxide in brain tissue.

    PubMed

    Santos, Ricardo M; Lourenço, Cátia F; Piedade, Ana P; Andrews, Rodney; Pomerleau, François; Huettl, Peter; Gerhardt, Greg A; Laranjinha, João; Barbosa, Rui M

    2008-12-01

    The measurement of Nitric oxide (NO) in real-time has been a major concern due to the involvement of this ubiquitous free radical modulator in several physiological and pathological pathways in tissues. Here we performed a study aiming at evaluating different types of carbon fibers, namely Textron, Amoco, Courtaulds and carbon nanotubes (University of Kentucky) covered with Nafion/o-phenylenediamine (o-PD) for NO measurement in terms of sensitivity, LOD, response time and selectivity against major potential interferents in the brain (ascorbate, nitrite and dopamine). The results indicate that, as compared with the other carbon fibers and nanotubes, Textron carbon fiber microelectrodes coated with two layers of Nafion and o-PD exhibited better characteristics for NO measurement as they are highly selective against ascorbate (>30,000:1), nitrite (>2000:1) and dopamine (>80:1). These coated Textron microelectrodes showed an average sensitivity of 341+/-120pA/microM and a detection limit of 16+/-11nM. The better performance of the Textron fibers is likely related to a stronger adhesion or more uniform coating of the Nafion and o-PD polymers to the fiber surface. In addition, the background current of the Textron carbon fibers is low, contributing to the excellent signal-to-noise for detection of NO. PMID:18657966

  4. Adhesive force measurement between HOPG and zinc oxide as an indicator for interfacial bonding of carbon fiber composites.

    PubMed

    Patterson, Brendan A; Galan, Ulises; Sodano, Henry A

    2015-07-22

    Vertically aligned zinc oxide (ZnO) nanowires have recently been utilized as an interphase to increase the interfacial strength of carbon fiber composites. It was shown that the interaction between the carbon fiber and the ZnO nanowires was a critical parameter in adhesion; however, fiber based testing techniques are dominated by local defects and cannot be used to effectively study the bonding interaction directly. Here, the strength of the interface between ZnO and graphitic carbon is directly measured with atomic force microscopy (AFM) using oxygen plasma treated highly oriented pyrolytic graphite (HOPG) and an AFM tip coated with ZnO nanoparticles. X-ray photoelectron spectroscopy analysis is used to compare the surface chemistry of HOPG and carbon fiber and to quantify the presence of various oxygen functional groups. An indirect measurement of the interfacial strength is then performed through single fiber fragmentation testing (SFF) on functionalized carbon fibers coated with ZnO nanowires to validate the AFM measurements. The SFF and AFM methods showed the same correlation, demonstrating the capacity of the AFM method to study the interfacial properties in composite materials. Additionally, the chemical interactions between oxygen functional groups and the ionic structure of ZnO suggest that intermolecular forces at the interface are responsible for the strong interface. PMID:26107931

  5. Biodistribution of antibody-targeted and non-targeted iron oxide nanoparticles in a breast cancer mouse model

    NASA Astrophysics Data System (ADS)

    Tate, Jennifer A.; Kett, Warren; NDong, Christian; Griswold, Karl E.; Hoopes, P. Jack

    2013-02-01

    Iron oxide nanoparticle (IONP) hyperthermia is a novel therapeutic strategy currently under consideration for the treatment of various cancer types. Systemic delivery of IONP followed by non-invasive activation via a local alternating magnetic field (AMF) results in site-specific energy deposition in the IONP-containing tumor. Targeting IONP to the tumor using an antibody or antibody fragment conjugated to the surface may enhance the intratumoral deposition of IONP and is currently being pursued by many nanoparticle researchers. This strategy, however, is subject to a variety of restrictions in the in vivo environment, where other aspects of IONP design will strongly influence the biodistribution. In these studies, various targeted IONP are compared to non-targeted controls. IONP were injected into BT-474 tumor-bearing NSG mice and tissues harvested 24hrs post-injection. Results indicate no significant difference between the various targeted IONP and the non-targeted controls, suggesting the IONP were prohibitively-sized to incur tumor penetration. Additional strategies are currently being pursued in conjuncture with targeted particles to increase the intratumoral deposition.

  6. Thermo-oxidative stability studies of PMR-15 polymer matrix composites reinforced with various continuous fibers

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.

    1990-01-01

    An experimental study was conducted to measure the thermooxidative stability of PMR-15 composites reinforced with various fibers and to observe differences in the way they degrade in air. The fibers studied include graphite and the thermally stable Nicalon and Nextel ceramic fibers. Weight-loss rates for the different composites were assessed as a function of mechanical properties, specimen geometry, fiber sizing, and interfacial bond strength. Differences were observed in rates of weight loss, matrix cracking, geometry dependency, and fiber sizing effects. It was shown that Celion 6000 fiber-reinforced composites do not exhibit a straight-line Arrhenius relationship at temperatures above 316 C.

  7. Free radical activity of industrial fibers: role of iron in oxidative stress and activation of transcription factors.

    PubMed Central

    Gilmour, P S; Brown, D M; Beswick, P H; MacNee, W; Rahman, I; Donaldson, K

    1997-01-01

    We studied asbestos, vitreous fiber (MMVF10), and refractory ceramic fiber (RCF1) from the Thermal Insulation Manufacturers' Association fiber repository regarding the following: free radical damage to plasmid DNA, iron release, ability to deplete glutathione (GSH), and activate redox-sensitive transcription factors in macrophages. Asbestos had much more free radical activity than any of the man-made vitreous fibers. More Fe3+ was released than Fe2+ and more of both was released at pH 4.5 than at pH 7.2. Release of iron from the different fibers was generally not a good correlate of ability to cause free radical injury to the plasmid DNA. All fiber types caused some degree of oxidative stress, as revealed by depletion of intracellular GSH. Amosite asbestos upregulated nuclear binding of activator protein 1 transcription factor to a greater level than MMVF10 and RCF1; long-fiber amosite was the only fiber to enhance activation of the transcription factor nuclear factor kappa B (NF kappa B). The use of cysteine methyl ester and buthionine sulfoximine to modulate GSH suggested that GSH homeostasis was important in leading to activation of transcription factors. We conclude that the intrinsic free radical activity is the major determinant of transcription factor activation and therefore gene expression in alveolar macrophages. Although this was not related to iron release or ability to deplete macrophage GSH at 4 hr, GSH does play a role in activation of NF kappa B. Images Figure 1. Figure 5. A Figure 5. B Figure 6. A Figure 6. B PMID:9400744

  8. Hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction for measurement of ibuprofen and naproxen in hair and waste water samples.

    PubMed

    Rezaeifar, Zohreh; Es'haghi, Zarrin; Rounaghi, Gholam Hossein; Chamsaz, Mahmoud

    2016-09-01

    A new design of hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction (HBP/GO -HF-SLPME) coupled with high performance liquid chromatography used for extraction and determination of ibuprofen and naproxen in hair and waste water samples. The graphene oxide first synthesized from graphite powders by using modified Hummers approach. The surface of graphene oxide was modified using hyperbranched polyglycerol, through direct polycondensation with thionyl chloride. The ready nanocomposite later wetted by a few microliter of an organic solvent (1-octanol), and then applied to extract the target analytes in direct immersion sampling mode.After the extraction process, the analytes were desorbed with methanol, and then detected via high performance liquid chromatography (HPLC). The experimental setup is very simple and highly affordable. The main factors influencing extraction such as; feed pH, extraction time, aqueous feed volume, agitation speed, the amount of functionalized graphene oxide and the desorption conditions have been examined in detail. Under the optimized experimental conditions, linearity was observed in the range of 5-30,000ngmL(-1) for ibuprofen and 2-10,000ngmL(-1) for naproxen with correlation coefficients of 0.9968 and 0.9925, respectively. The limits of detection were 2.95ngmL(-1) for ibuprofen and 1.51ngmL(-1) for naproxen. The relative standard deviations (RSDs) were found to be less than 5% (n=5). PMID:27428449

  9. Fatty acid oxidation and carnitine palmitoyltransferase I: emerging therapeutic targets in cancer

    PubMed Central

    Qu, Q; Zeng, F; Liu, X; Wang, Q J; Deng, F

    2016-01-01

    Tumor cells exhibit unique metabolic adaptations that are increasingly viewed as potential targets for novel and specific cancer therapies. Among these targets, the carnitine palmitoyltransferase system is responsible for delivering the long-chain fatty acid (FA) from cytoplasm into mitochondria for oxidation, where carnitine palmitoyltransferase I (CPTI) catalyzes the rate-limiting step of fatty acid oxidation (FAO). With increasing understanding of the crucial role had by fatty acid oxidation in cancer, CPTI has received renewed attention as a pivotal mediator in cancer metabolic mechanism. CPTI activates FAO and fuels cancer growth via ATP and NADPH production, constituting an essential part of cancer metabolism adaptation. Moreover, CPTI also functionally intertwines with other key pathways and factors to regulate gene expression and apoptosis of cancer cell. Here, we summarize recent findings and update the current understanding of FAO and CPTI in cancer and provide theoretical basis for this enzyme as an emerging potential molecular target in cancer therapeutic intervention. PMID:27195673

  10. Fatty acid oxidation and carnitine palmitoyltransferase I: emerging therapeutic targets in cancer.

    PubMed

    Qu, Q; Zeng, F; Liu, X; Wang, Q J; Deng, F

    2016-01-01

    Tumor cells exhibit unique metabolic adaptations that are increasingly viewed as potential targets for novel and specific cancer therapies. Among these targets, the carnitine palmitoyltransferase system is responsible for delivering the long-chain fatty acid (FA) from cytoplasm into mitochondria for oxidation, where carnitine palmitoyltransferase I (CPTI) catalyzes the rate-limiting step of fatty acid oxidation (FAO). With increasing understanding of the crucial role had by fatty acid oxidation in cancer, CPTI has received renewed attention as a pivotal mediator in cancer metabolic mechanism. CPTI activates FAO and fuels cancer growth via ATP and NADPH production, constituting an essential part of cancer metabolism adaptation. Moreover, CPTI also functionally intertwines with other key pathways and factors to regulate gene expression and apoptosis of cancer cell. Here, we summarize recent findings and update the current understanding of FAO and CPTI in cancer and provide theoretical basis for this enzyme as an emerging potential molecular target in cancer therapeutic intervention. PMID:27195673

  11. Exogenous Nitric Oxide Suppresses in Vivo X-ray-Induced Targeted and Non-Targeted Effects in Zebrafish Embryos

    PubMed Central

    Kong, E.Y.; Yeung, W.K.; Chan, T.K.Y.; Cheng, S.H.; Yu, K.N.

    2016-01-01

    The present paper studied the X-ray-induced targeted effect in irradiated zebrafish embryos (Danio rerio), as well as a non-targeted effect in bystander naïve embryos partnered with irradiated embryos, and examined the influence of exogenous nitric oxide (NO) on these targeted and non-targeted effects. The exogenous NO was generated using an NO donor, S-nitroso-N-acetylpenicillamine (SNAP). The targeted and non-targeted effects, as well as the toxicity of the SNAP, were assessed using the number of apoptotic events in the zebrafish embryos at 24 h post fertilization (hpf) revealed through acridine orange (AO) staining. SNAP with concentrations of 20 and 100 µM were first confirmed to have no significant toxicity on zebrafish embryos. The targeted effect was mitigated in zebrafish embryos if they were pretreated with 100 µM SNAP prior to irradiation with an X-ray dose of 75 mGy but was not alleviated in zebrafish embryos if they were pretreated with 20 µM SNAP. On the other hand, the non-targeted effect was eliminated in the bystander naïve zebrafish embryos if they were pretreated with 20 or 100 µM SNAP prior to partnering with zebrafish embryos having been subjected to irradiation with an X-ray dose of 75 mGy. These findings revealed the importance of NO in the protection against damages induced by ionizing radiations or by radiation-induced bystander signals, and could have important impacts on development of advanced cancer treatment strategies. PMID:27529238

  12. Carbon fiber composite targets for nuclear fusion technology: a focused ion beam/scanning electron microscope investigation.

    PubMed

    Ghezzi, F; Magni, S; Milani, M; Tatti, F

    2007-01-01

    Carbon fiber composite (CFC) targets are investigated by a focused ion beam/scanning electron microscope (FIB/SEM) in a joint project aiming at the development of robust divertors in the International Thermonuclear Experimental Reactor (ITER). These mockups are exposed to a plasma that simulates the off-normal thermal loads foreseen for ITER and display a rich, puzzling impact scenario. Morphological elements are identified at the exposed surface and beneath it, and are examined in order to point out the relevant processes involved. Each technique adopted is discussed and evaluated. PMID:18200678

  13. Drug Targets for Oxidative Podocyte Injury in Diabetic Nephropathy

    PubMed Central

    Usman, Muhammad

    2015-01-01

    Diabetic nephropathy (DN) is one the most prevalent chronic complications of diabetes mellitus that affects as much as one-third of diabetic patients irrespective of the type of diabetes. Hyperglycemia is the key trigger for DN that initiates a number of microscopic and ultramicroscopic changes in kidney architecture. Microscopic changes include thickening of the glomerular basement membrane (GBM), tubular basement membrane (TBM), mesangial proliferation, arteriosclerosis, and glomerulotubular junction abnormalities (GTJA). Among the ultramicroscopic changes, effacement of podocytes and decrease in their density seem to be the centerpiece of DN pathogenesis. These changes in kidney architecture then produce functional deficits, such as microalbuminuria and decreased glomerular filtration rate (GFR). Among several mechanisms involved in inflicting damage to podocytes, injuries sustained by increased oxidative stress turns out to be the most important mechanism. Different variables that are included in increased production of reactive oxygen species (ROS) include a hyperglycemia-induced reduction in glutathione (GSH), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation via hyperglycemia, advanced glycation end products (AGEs), protein kinase C (PKC), and renin-angiotensin-aldosterone system (RAAS). Unfortunately, control of podocyte injury hasn’t received much attention as a treatment approach for DN. Therefore, this review article is mainly concerned with the exploration of various treatment options that might help in decreasing the podocyte injury, mainly by reducing the level of NADPH oxidase-mediated generation of ROS. This article concludes with a view that certain NADPH oxidase inhibitors, RAAS inhibitors, statins, antidiabetic drugs, and antioxidant vitamins might be useful in decreasing podocyte injury and resultant structural and functional kidney impairments in DN. PMID:26798569

  14. Drug Targets for Oxidative Podocyte Injury in Diabetic Nephropathy.

    PubMed

    Bhatti, Adnan Bashir; Usman, Muhammad

    2015-01-01

    Diabetic nephropathy (DN) is one the most prevalent chronic complications of diabetes mellitus that affects as much as one-third of diabetic patients irrespective of the type of diabetes. Hyperglycemia is the key trigger for DN that initiates a number of microscopic and ultramicroscopic changes in kidney architecture. Microscopic changes include thickening of the glomerular basement membrane (GBM), tubular basement membrane (TBM), mesangial proliferation, arteriosclerosis, and glomerulotubular junction abnormalities (GTJA). Among the ultramicroscopic changes, effacement of podocytes and decrease in their density seem to be the centerpiece of DN pathogenesis. These changes in kidney architecture then produce functional deficits, such as microalbuminuria and decreased glomerular filtration rate (GFR). Among several mechanisms involved in inflicting damage to podocytes, injuries sustained by increased oxidative stress turns out to be the most important mechanism. Different variables that are included in increased production of reactive oxygen species (ROS) include a hyperglycemia-induced reduction in glutathione (GSH), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation via hyperglycemia, advanced glycation end products (AGEs), protein kinase C (PKC), and renin-angiotensin-aldosterone system (RAAS). Unfortunately, control of podocyte injury hasn't received much attention as a treatment approach for DN. Therefore, this review article is mainly concerned with the exploration of various treatment options that might help in decreasing the podocyte injury, mainly by reducing the level of NADPH oxidase-mediated generation of ROS. This article concludes with a view that certain NADPH oxidase inhibitors, RAAS inhibitors, statins, antidiabetic drugs, and antioxidant vitamins might be useful in decreasing podocyte injury and resultant structural and functional kidney impairments in DN. PMID:26798569

  15. The Immature Fiber Mutant Phenotype of Cotton (Gossypium hirsutum) Is Linked to a 22-bp Frame-Shift Deletion in a Mitochondria Targeted Pentatricopeptide Repeat Gene

    PubMed Central

    Thyssen, Gregory N.; Fang, David D.; Zeng, Linghe; Song, Xianliang; Delhom, Christopher D.; Condon, Tracy L.; Li, Ping; Kim, Hee Jin

    2016-01-01

    Cotton seed trichomes are the most important source of natural fibers globally. The major fiber thickness properties influence the price of the raw material, and the quality of the finished product. The recessive immature fiber (im) gene reduces the degree of fiber cell wall thickening by a process that was previously shown to involve mitochondrial function in allotetraploid Gossypium hirsutum. Here, we present the fine genetic mapping of the im locus, gene expression analysis of annotated proteins near the locus, and association analysis of the linked markers. Mapping-by-sequencing identified a 22-bp deletion in a pentatricopeptide repeat (PPR) gene that is completely linked to the immature fiber phenotype in 2837 F2 plants, and is absent from all 163 cultivated varieties tested, although other closely linked marker polymorphisms are prevalent in the diversity panel. This frame-shift mutation results in a transcript with two long open reading frames: one containing the N-terminal transit peptide that targets mitochondria, the other containing only the RNA-binding PPR domains, suggesting that a functional PPR protein cannot be targeted to mitochondria in the im mutant. Taken together, these results suggest that PPR gene Gh_A03G0489 is involved in the cotton fiber wall thickening process, and is a promising candidate gene at the im locus. Our findings expand our understanding of the molecular mechanisms that modulate cotton fiber fineness and maturity, and may facilitate the development of cotton varieties with superior fiber attributes. PMID:27172184

  16. The Immature Fiber Mutant Phenotype of Cotton (Gossypium hirsutum) Is Linked to a 22-bp Frame-Shift Deletion in a Mitochondria Targeted Pentatricopeptide Repeat Gene.

    PubMed

    Thyssen, Gregory N; Fang, David D; Zeng, Linghe; Song, Xianliang; Delhom, Christopher D; Condon, Tracy L; Li, Ping; Kim, Hee Jin

    2016-01-01

    Cotton seed trichomes are the most important source of natural fibers globally. The major fiber thickness properties influence the price of the raw material, and the quality of the finished product. The recessive immature fiber (im) gene reduces the degree of fiber cell wall thickening by a process that was previously shown to involve mitochondrial function in allotetraploid Gossypium hirsutum Here, we present the fine genetic mapping of the im locus, gene expression analysis of annotated proteins near the locus, and association analysis of the linked markers. Mapping-by-sequencing identified a 22-bp deletion in a pentatricopeptide repeat (PPR) gene that is completely linked to the immature fiber phenotype in 2837 F2 plants, and is absent from all 163 cultivated varieties tested, although other closely linked marker polymorphisms are prevalent in the diversity panel. This frame-shift mutation results in a transcript with two long open reading frames: one containing the N-terminal transit peptide that targets mitochondria, the other containing only the RNA-binding PPR domains, suggesting that a functional PPR protein cannot be targeted to mitochondria in the im mutant. Taken together, these results suggest that PPR gene Gh_A03G0489 is involved in the cotton fiber wall thickening process, and is a promising candidate gene at the im locus. Our findings expand our understanding of the molecular mechanisms that modulate cotton fiber fineness and maturity, and may facilitate the development of cotton varieties with superior fiber attributes. PMID:27172184

  17. Oxidation of Carbon Fibers in a Cracked Ceramic Matrix Composite Modeled as a Function of Temperature

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.; Cawley, James D.; Eckel, Andrew J.

    2003-01-01

    The oxidation model simulates the oxidation of the reinforcing carbon fibers within a ceramic matrix composite material containing as-fabricated microcracks. The physics-based oxidation model uses theoretically and experimentally determined variables as input for the model. The model simulates the ingress of oxygen through microcracks into a two-dimensional plane within the composite material. Model input includes temperature, oxygen concentration, the reaction rate constant, the diffusion coefficient, and the crack opening width as a function of the mechanical and thermal loads. The model is run in an iterative process for a two-dimensional grid system in which oxygen diffuses through the porous and cracked regions of the material and reacts with carbon in short time steps. The model allows the local oxygen concentrations and carbon volumes from the edge to the interior of the composite to be determined over time. Oxidation damage predicted by the model was compared with that observed from microstructural analysis of experimentally tested composite material to validate the model for two temperatures of interest. When the model is run for low-temperature conditions, the kinetics are reaction controlled. Carbon and oxygen reactions occur relatively slowly. Therefore, oxygen can bypass the carbon near the outer edge and diffuse into the interior so that it saturates the entire composite at relatively high concentrations. The kinetics are limited by the reaction rate between carbon and oxygen. This results in an interior that has high local concentrations of oxygen and a similar amount of consumed carbon throughout the cross section. When the model is run for high-temperature conditions, the kinetics are diffusion controlled. Carbon and oxygen reactions occur very quickly. The carbon consumes oxygen as soon as it is supplied. The kinetics are limited by the relatively slow rate at which oxygen is supplied in comparison to the relatively fast rate at which carbon and

  18. Structural characterization and photocatalytic activity of hollow binary ZrO{sub 2}/TiO{sub 2} oxide fibers

    SciTech Connect

    Wu Baochao; Yuan Rusheng Fu Xianzhi

    2009-03-15

    The formation of hollow binary ZrO{sub 2}/TiO{sub 2} oxide fibers using mixed precursor solutions was achieved by activated carbon fibers templating technique combined with solvothermal process. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N{sub 2} adsorption, X-ray photoelectron spectroscopy (XPS), UV-vis, and infrared (IR) spectroscopy. The binary oxide system shows the anatase-type TiO{sub 2} and tetragonal phase of ZrO{sub 2}, and the introduction of ZrO{sub 2} notably inhibits the growth of TiO{sub 2} nanocrystallites. Although calcined at 575 deg. C, all hollow ZrO{sub 2}/TiO{sub 2} fibers exhibit higher surface areas (>113 m{sup 2}/g) than pure TiO{sub 2} hollow fibers. The Pyridine adsorption on ZrO{sub 2}/TiO{sub 2} sample indicates the presence of stronger surface acid sites. Such properties bring about that the binary oxide system possesses higher efficiency and durable activity stability for photodegradation of gaseous ethylene and trichloromethane than P25 TiO{sub 2}. In addition, the macroscopic felt form for the resulting materials is more beneficial for practical applications than traditional catalysts forms. - Graphical abstract: The final ZrO{sub 2}/TiO{sub 2} products composed of hollow fibers are in the form of felt on the centimeter scale and possess certain strength and flexibleness. Moreover, they exhibit excellent efficiency and durable activity stability for photodegradation of gaseous ethylene and trichloromethane, reaching about 136% and 387% of the P25 activity after 10 h, respectively.

  19. Targeting oxidant-dependent mechanisms for the treatment of COPD and its comorbidities.

    PubMed

    Bernardo, Ivan; Bozinovski, Steven; Vlahos, Ross

    2015-11-01

    Chronic obstructive pulmonary disease (COPD) is an incurable global health burden and is characterised by progressive airflow limitation and loss of lung function. In addition to the pulmonary impact of the disease, COPD patients often develop comorbid diseases such as cardiovascular disease, skeletal muscle wasting, lung cancer and osteoporosis. One key feature of COPD, yet often underappreciated, is the contribution of oxidative stress in the onset and development of the disease. Patients experience an increased burden of oxidative stress due to the combined effects of excess reactive oxygen species (ROS) and nitrogen species (RNS) generation, antioxidant depletion and reduced antioxidant enzyme activity. Currently, there is a lack of effective treatments for COPD, and an even greater lack of research regarding interventions that treat both COPD and its comorbidities. Due to the involvement of oxidative stress in the pathogenesis of COPD and many of its comorbidities, a unique therapeutic opportunity arises where the treatment of a multitude of diseases may be possible with only one therapeutic target. In this review, oxidative stress and the roles of ROS/RNS in the context of COPD and comorbid cardiovascular disease, skeletal muscle wasting, lung cancer, and osteoporosis are discussed and the potential for therapeutic benefit of anti-oxidative treatment in these conditions is outlined. Because of the unique interplay between oxidative stress and these diseases, oxidative stress represents a novel target for the treatment of COPD and its comorbidities. PMID:26297673

  20. Understanding the Impact of Poly(ethylene oxide) on the Assembly of Lignin in Solution toward Improved Carbon Fiber Production.

    PubMed

    Imel, Adam E; Naskar, Amit K; Dadmun, Mark D

    2016-02-10

    Carbon fiber produced from lignin has recently become an industrial scalable product with applications ranging from thermal insulation to reinforcing automobile bodies. Previous research has shown that mixing 1-2 wt %, of poly(ethylene oxide) (PEO) with the lignin before fiber formation can enhance the properties of the final carbon fibers. The research reported here determines the impact of adding PEO to a lignin solution on its assembly, focusing on the role of the lignin structure on this assembly process. Results indicate the addition of PEO anisotropically directs the self-assembly of the hardwood and softwood lignin by lengthening the cylindrical building blocks that make up the larger global aggregates. On the other hand, results from an annual lignin exhibit a shapeless, more complex structure with a unique dependence on the PEO loading. These results are consistent with improved carbon fibers from solutions of lignin that include PEO, as the local ordering and directed assembly will inhibit the formation of defects during the carbon fiber fabrication process. PMID:26756927

  1. Effects of working pressure on physical properties of tungsten-oxide thin films sputtered from oxide target

    SciTech Connect

    Riech, I.; Acosta, M.; Pena, J. L.; Bartolo-Perez, P.

    2010-03-15

    Tungsten-oxide films were deposited on glass substrates from a metal-oxide target by nonreactive radio-frequency sputtering. The authors have studied the effect that changing Ar gas pressure has on the electrical, optical, and chemical composition in the thin films. Resistivity of WO{sub 3} changed ten orders of magnitude with working gas pressure values from 20 to 80 mTorr. Thin films deposited at 20 mTorr of Ar sputtering pressure showed lower resistivity and optical transmittance. X-ray photoelectron spectroscopy (XPS) measurements revealed similar chemical composition for all samples irrespective of Ar pressure used. However, XPS analyses of the evolution of W 4f and O 1s peaks indicated a mixture of oxides dependent on the Ar pressure used during deposition.

  2. Te/Pt nanonetwork modified carbon fiber microelectrodes for methanol oxidation

    NASA Astrophysics Data System (ADS)

    Tsai, Hsiang-Yu; Shih, Zih-Yu; Lin, Zong-Hong; Chang, Huan-Tsung

    2013-05-01

    Te/Pt nanonetwork-decorated carbon fiber microelectrodes (CFMEs) have been fabricated and employed as anodic catalysts in a direct methanol fuel cell (DMFC). Te nanowires were prepared from tellurite ions (TeO32-) through a seed-mediated growth process and were deposited onto CFMEs to form three-dimensional Te nanonetworks. The Te nanonetworks then acted as a framework and reducing agent to reduce PtCl62- ions to form Te/Pt through a galvanic replacement reaction, leading to the formation of Te/PtCFMEs. By controlling the reaction time, the amount of Pt and morphology of Te/Pt nanonetworks were controlled, leading to various degrees of electrocatalytic activity. The Te/PtCFMEs provide a high electrochemical active surface area (129.2 m2 g-1), good catalytic activity (1.2 A mg-1), high current density (20.0 mA cm-2), long durability, and tolerance toward the poisoning species for methanol oxidation in 0.5 M sulfuric acid containing 1 M methanol. We have further demonstrated an enhanced current density by separately using 3 and 5 Te/PtCFMEs. Our results show that the low-cost, stable, and effective Te/PtCFMEs have great potential in the fabrication of cost-effective fuel cells.

  3. Te/Pt nanonetwork modified carbon fiber microelectrodes for methanol oxidation.

    PubMed

    Tsai, Hsiang-Yu; Shih, Zih-Yu; Lin, Zong-Hong; Chang, Huan-Tsung

    2013-05-17

    Te/Pt nanonetwork-decorated carbon fiber microelectrodes (CFMEs) have been fabricated and employed as anodic catalysts in a direct methanol fuel cell (DMFC). Te nanowires were prepared from tellurite ions (TeO3(2-)) through a seed-mediated growth process and were deposited onto CFMEs to form three-dimensional Te nanonetworks. The Te nanonetworks then acted as a framework and reducing agent to reduce PtCl6(2-) ions to form Te/Pt through a galvanic replacement reaction, leading to the formation of Te/PtCFMEs. By controlling the reaction time, the amount of Pt and morphology of Te/Pt nanonetworks were controlled, leading to various degrees of electrocatalytic activity. The Te/PtCFMEs provide a high electrochemical active surface area (129.2 m(2) g(-1)), good catalytic activity (1.2 A mg(-1)), high current density (20.0 mA cm(-2)), long durability, and tolerance toward the poisoning species for methanol oxidation in 0.5 M sulfuric acid containing 1 M methanol. We have further demonstrated an enhanced current density by separately using 3 and 5 Te/PtCFMEs. Our results show that the low-cost, stable, and effective Te/PtCFMEs have great potential in the fabrication of cost-effective fuel cells. PMID:23579734

  4. Increase of the deposition rate in reactive sputtering of metal oxides using a ceramic nitride target

    SciTech Connect

    Severin, D.; Wuttig, M.; Kappertz, O.; Nyberg, T.; Berg, S.; Pflug, A.

    2009-05-01

    We present a method to eliminate hysteresis effects and to increase the deposition rate for the reactive sputtering of metal oxides. This is achieved by using a ceramic nitride target in an argon-oxygen atmosphere. Although the use of a ceramic nitride target leads to pronounced changes of the processing characteristics, incorporation of nitrogen into the growing film is very small. These observations can be theoretically predicted using an extension of Berg's model [S. Berg and T. Nyberg, Thin Solid Films 476, 215 (2005)] to two different reactive gases and a compound target.

  5. Maximal oxygen uptake is proportional to muscle fiber oxidative capacity, from chronic heart failure patients to professional cyclists.

    PubMed

    van der Zwaard, Stephan; de Ruiter, Jo C; Noordhof, Dionne A; Sterrenburg, Renske; Bloemers, Frank W; de Koning, Jos J; Jaspers, Richard T; van der Laarse, Willem J

    2016-09-01

    V̇o2 max during whole body exercise is presumably constrained by oxygen delivery to mitochondria rather than by mitochondria's ability to consume oxygen. Humans and animals have been reported to exploit only 60-80% of their mitochondrial oxidative capacity at maximal oxygen uptake (V̇o2 max). However, ex vivo quantification of mitochondrial overcapacity is complicated by isolation or permeabilization procedures. An alternative method for estimating mitochondrial oxidative capacity is via enzyme histochemical quantification of succinate dehydrogenase (SDH) activity. We determined to what extent V̇o2 max attained during cycling exercise differs from mitochondrial oxidative capacity predicted from SDH activity of vastus lateralis muscle in chronic heart failure patients, healthy controls, and cyclists. V̇o2 max was assessed in 20 healthy subjects and 28 cyclists, and SDH activity was determined from biopsy cryosections of vastus lateralis using quantitative histochemistry. Similar data from our laboratory of 14 chronic heart failure patients and 6 controls were included. Mitochondrial oxidative capacity was predicted from SDH activity using estimated skeletal muscle mass and the relationship between ex vivo fiber V̇o2 max and SDH activity of isolated single muscle fibers and myocardial trabecula under hyperoxic conditions. Mitochondrial oxidative capacity predicted from SDH activity was related (r(2) = 0.89, P < 0.001) to V̇o2 max measured during cycling in subjects with V̇o2 max ranging from 9.8 to 79.0 ml·kg(-1)·min(-1) V̇o2 max measured during cycling was on average 90 ± 14% of mitochondrial oxidative capacity. We conclude that human V̇o2 max is related to mitochondrial oxidative capacity predicted from skeletal muscle SDH activity. Mitochondrial oxidative capacity is likely marginally limited by oxygen supply to mitochondria. PMID:27445298

  6. Targeting multiple types of tumors using NKG2D-coated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Ru; Cook, W. James; Zhang, Tong; Sentman, Charles L.

    2014-11-01

    Iron oxide nanoparticles (IONPs) hold great potential for cancer therapy. Actively targeting IONPs to tumor cells can further increase therapeutic efficacy and decrease off-target side effects. To target tumor cells, a natural killer (NK) cell activating receptor, NKG2D, was utilized to develop pan-tumor targeting IONPs. NKG2D ligands are expressed on many tumor types and its ligands are not found on most normal tissues under steady state conditions. The data showed that mouse and human fragment crystallizable (Fc)-fusion NKG2D (Fc-NKG2D) coated IONPs (NKG2D/NPs) can target multiple NKG2D ligand positive tumor types in vitro in a dose dependent manner by magnetic cell sorting. Tumor targeting effect was robust even under a very low tumor cell to normal cell ratio and targeting efficiency correlated with NKG2D ligand expression level on tumor cells. Furthermore, the magnetic separation platform utilized to test NKG2D/NP specificity has the potential to be developed into high throughput screening strategies to identify ideal fusion proteins or antibodies for targeting IONPs. In conclusion, NKG2D/NPs can be used to target multiple tumor types and magnetic separation platform can facilitate the proof-of-concept phase of tumor targeting IONP development.

  7. Targeting multiple types of tumors using NKG2D-coated iron oxide nanoparticles

    PubMed Central

    Wu, Ming-Ru; Cook, W. James; Zhang, Tong; Sentman, Charles L.

    2015-01-01

    Iron oxide nanoparticles (IONPs) hold great potential for cancer therapy. Actively targeting IONPs to tumor cells can further increase therapeutic efficacy and decrease off-target side effects. To target tumor cells, a natural killer (NK) cell activating receptor, NKG2D, was utilized to develop pan-tumor targeting IONPs. NKG2D ligands are expressed on many tumor types and its ligands are not found on most normal tissues under steady state conditions. The data showed that mouse and human fragment crystallizable (Fc) -fusion NKG2D (Fc-NKG2D) coated IONPs (NKG2D/NPs) can target multiple NKG2D ligand positive tumor types in vitro in a dose dependent manner by magnetic cell sorting. Tumor targeting effect was robust even under a very low tumor cell to normal cell ratio and targeting efficiency correlated with NKG2D ligand expression level on tumor cells. Furthermore, the magnetic separation platform utilized to test NKG2D/NP specificity has the potential to be developed into high throughput screening strategies to identify ideal fusion proteins or antibodies for targeting IONPs. In conclusion, NKG2D/NPs can be used to target multiple tumor types and magnetic separation platform can facilitate the proof-of-concept phase of tumor targeting IONP development. PMID:25371538

  8. microRNAs: Emerging Targets Regulating Oxidative Stress in the Models of Parkinson's Disease

    PubMed Central

    Xie, Yangmei; Chen, Yinghui

    2016-01-01

    Parkinson's disease (PD) is the second most common neurodegenerative disorder. This chronic, progressive disease is characterized by loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and the presence of cytoplasmic inclusions called Lewy bodies (LBs) in surviving neurons. PD is attributed to a combination of environment and genetic factors, but the precise underlying molecular mechanisms remain elusive. Oxidative stress is generally recognized as one of the main causes of PD, and excessive reactive oxygen species (ROS) can lead to DA neuron vulnerability and eventual death. Several studies have demonstrated that small non-coding RNAs termed microRNAs (miRNAs) can regulate oxidative stress in vitro and in vivo models of PD. Relevant miRNAs involved in oxidative stress can prevent ROS-mediated damage to DA neurons, suggesting that specific miRNAs may be putative targets for novel therapeutic targets in PD. PMID:27445669

  9. Chlorotoxin-conjugated graphene oxide for targeted delivery of an anticancer drug.

    PubMed

    Wang, Hao; Gu, Wei; Xiao, Ning; Ye, Ling; Xu, Qunyuan

    2014-01-01

    Current chemotherapy for glioma is rarely satisfactory due to low therapeutic efficiency and systemic side effects. We have developed a glioma-targeted drug delivery system based on graphene oxide. Targeted peptide chlorotoxin-conjugated graphene oxide (CTX-GO) sheets were successfully synthesized and characterized. Doxorubicin was loaded onto CTX-GO (CTX-GO/DOX) with high efficiency (570 mg doxorubicin per gram CTX-GO) via noncovalent interactions. Doxorubicin release was pH-dependent and showed sustained-release properties. Cytotoxicity experiments demonstrated that CTX-GO/DOX mediated the highest rate of death of glioma cells compared with free doxorubicin or graphene oxide loaded with doxorubicin only. Further, conjugation with chlorotoxin enhanced accumulation of doxorubicin within glioma cells. These findings indicate that CTX-GO is a promising platform for drug delivery and provide a rationale for developing a glioma-specific drug delivery system. PMID:24672236

  10. Glycolytic-to-oxidative fiber-type switch and mTOR signaling activation are early-onset features of SBMA muscle modified by high-fat diet.

    PubMed

    Rocchi, Anna; Milioto, Carmelo; Parodi, Sara; Armirotti, Andrea; Borgia, Doriana; Pellegrini, Matteo; Urciuolo, Anna; Molon, Sibilla; Morbidoni, Valeria; Marabita, Manuela; Romanello, Vanina; Gatto, Pamela; Blaauw, Bert; Bonaldo, Paolo; Sambataro, Fabio; Robins, Diane M; Lieberman, Andrew P; Sorarù, Gianni; Vergani, Lodovica; Sandri, Marco; Pennuto, Maria

    2016-07-01

    Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by the expansion of a polyglutamine tract in the androgen receptor (AR). The mechanism by which expansion of polyglutamine in AR causes muscle atrophy is unknown. Here, we investigated pathological pathways underlying muscle atrophy in SBMA knock-in mice and patients. We show that glycolytic muscles were more severely affected than oxidative muscles in SBMA knock-in mice. Muscle atrophy was associated with early-onset, progressive glycolytic-to-oxidative fiber-type switch. Whole genome microarray and untargeted lipidomic analyses revealed enhanced lipid metabolism and impaired glycolysis selectively in muscle. These metabolic changes occurred before denervation and were associated with a concurrent enhancement of mechanistic target of rapamycin (mTOR) signaling, which induced peroxisome proliferator-activated receptor γ coactivator 1 alpha (PGC1α) expression. At later stages of disease, we detected mitochondrial membrane depolarization, enhanced transcription factor EB (TFEB) expression and autophagy, and mTOR-induced protein synthesis. Several of these abnormalities were detected in the muscle of SBMA patients. Feeding knock-in mice a high-fat diet (HFD) restored mTOR activation, decreased the expression of PGC1α, TFEB, and genes involved in oxidative metabolism, reduced mitochondrial abnormalities, ameliorated muscle pathology, and extended survival. These findings show early-onset and intrinsic metabolic alterations in SBMA muscle and link lipid/glucose metabolism to pathogenesis. Moreover, our results highlight an HFD regime as a promising approach to support SBMA patients. PMID:26971100

  11. Lipidomics identifies cardiolipin oxidation as a mitochondrial target for redox therapy of brain injury.

    PubMed

    Ji, Jing; Kline, Anthony E; Amoscato, Andrew; Samhan-Arias, Alejandro K; Sparvero, Louis J; Tyurin, Vladimir A; Tyurina, Yulia Y; Fink, Bruno; Manole, Mioara D; Puccio, Ava M; Okonkwo, David O; Cheng, Jeffrey P; Alexander, Henry; Clark, Robert S B; Kochanek, Patrick M; Wipf, Peter; Kagan, Valerian E; Bayır, Hülya

    2012-10-01

    The brain contains a highly diversified complement of molecular species of a mitochondria-specific phospholipid, cardiolipin, which, because of its polyunsaturation, can readily undergo oxygenation. Using global lipidomics analysis in experimental traumatic brain injury (TBI), we found that TBI was accompanied by oxidative consumption of polyunsaturated cardiolipin and the accumulation of more than 150 new oxygenated molecular species of cardiolipin. RNAi-based manipulations of cardiolipin synthase and cardiolipin levels conferred resistance to mechanical stretch, an in vitro model of traumatic neuronal injury, in primary rat cortical neurons. By applying a brain-permeable mitochondria-targeted electron scavenger, we prevented cardiolipin oxidation in the brain, achieved a substantial reduction in neuronal death both in vitro and in vivo, and markedly reduced behavioral deficits and cortical lesion volume. We conclude that cardiolipin oxygenation generates neuronal death signals and that prevention of it by mitochondria-targeted small molecule inhibitors represents a new target for neuro-drug discovery. PMID:22922784

  12. Meat quality, oxidative stability and blood parameters from Graylag geese offered alternative fiber sources in growing period.

    PubMed

    He, L W; Meng, Q X; Li, D Y; Zhang, Y W; Ren, L P

    2015-04-01

    The effects of dietary fiber sources on the meat quality, oxidative stability, and blood parameters of growing Graylag geese (28-112d) were investigated. The birds were randomly allocated into 4 treatments, of which dietary fiber was mainly from corn straw silage (CSS), steam-exploded corn straw (SECS), steam-exploded wheat straw (SEWS), and steam-exploded rice straw (SERS). No influence (P>0.05) on the basic chemical components, oxidative stability, or organoleptic traits of muscle were observed, except that birds fed SECS had a higher (P<0.05) protein proportion than those fed CSS or SERS, and CSS increased (P<0.01) the cholesterol content when compared to SEWS or SERS. Regarding fatty acid profile in meat, CSS and SECS increased (P<0.01) the proportion of C18:2n6t and decreased that of C21:0 and C22:0 when compared to the others. The birds fed SERS had a higher (P<0.05) proportion of C20:0 and C22:0 than the others, a higher proportion of C20:5n3, n-3 fatty acids, Δ-9 desaturase (18) index compared to those fed CSS or SECS, and a lower (P<0.01) proportion of C20:1n9 than those fed SECS or SEWS. Additionally, SEWS resulted in a higher (P<0.01) proportion of C20:2 when compared to the others. In conclusion, these fibers affect just the protein proportion, cholesterol content, and fatty acid profile of breast muscle, along with the concentration of TG and MDA in blood, but not the other characteristics. No superior fiber source exists with respect to meat quality, suggesting that Graylag geese feeding should make the most economically of the convenient fiber source with appropriate pretreatment. PMID:25717090

  13. Method of producing superconducting fibers of bismuth strontium calcium copper oxide (Bi(2212) and Bi(2223))

    DOEpatents

    Schwartzkopf, Louis A.

    1991-10-01

    Fibers of Bi(2212) have been produce by pendant drop melt extraction. This technique involves the end of a rod of Bi(2212) melted with a hydrogen-oxygen torch, followed by lowering onto the edge of a spinning wheel. The fibers are up to 15 cm in length with the usual lateral dimensions, ranging from 20 um to 30 um. The fibers require a heat treatment to make them superconducting.

  14. Long circulating reduced graphene oxide-iron oxide nanoparticles for efficient tumor targeting and multimodality imaging.

    PubMed

    Xu, Cheng; Shi, Sixiang; Feng, Liangzhu; Chen, Feng; Graves, Stephen A; Ehlerding, Emily B; Goel, Shreya; Sun, Haiyan; England, Christopher G; Nickles, Robert J; Liu, Zhuang; Wang, Taihong; Cai, Weibo

    2016-07-01

    Polyethylene glycol (PEG) surface modification is one of the most widely used approaches to improve the solubility of inorganic nanoparticles, prevent their aggregation and prolong their in vivo blood circulation half-life. Herein, we developed double-PEGylated biocompatible reduced graphene oxide nanosheets anchored with iron oxide nanoparticles (RGO-IONP-(1st)PEG-(2nd)PEG). The nanoconjugates exhibited a prolonged blood circulation half-life (∼27.7 h) and remarkable tumor accumulation (>11 %ID g(-1)) via an enhanced permeability and retention (EPR) effect. Due to the strong near-infrared absorbance and superparamagnetism of RGO-IONP-(1st)PEG-(2nd)PEG, multimodality imaging combining positron emission tomography (PET) imaging with magnetic resonance imaging (MRI) and photoacoustic (PA) imaging was successfully achieved. The promising results suggest the great potential of these nanoconjugates for multi-dimensional and more accurate tumor diagnosis and therapy in the future. PMID:27109431

  15. Long circulating reduced graphene oxide-iron oxide nanoparticles for efficient tumor targeting and multimodality imaging

    NASA Astrophysics Data System (ADS)

    Xu, Cheng; Shi, Sixiang; Feng, Liangzhu; Chen, Feng; Graves, Stephen A.; Ehlerding, Emily B.; Goel, Shreya; Sun, Haiyan; England, Christopher G.; Nickles, Robert J.; Liu, Zhuang; Wang, Taihong; Cai, Weibo

    2016-06-01

    Polyethylene glycol (PEG) surface modification is one of the most widely used approaches to improve the solubility of inorganic nanoparticles, prevent their aggregation and prolong their in vivo blood circulation half-life. Herein, we developed double-PEGylated biocompatible reduced graphene oxide nanosheets anchored with iron oxide nanoparticles (RGO-IONP-1stPEG-2ndPEG). The nanoconjugates exhibited a prolonged blood circulation half-life (~27.7 h) and remarkable tumor accumulation (>11 %ID g-1) via an enhanced permeability and retention (EPR) effect. Due to the strong near-infrared absorbance and superparamagnetism of RGO-IONP-1stPEG-2ndPEG, multimodality imaging combining positron emission tomography (PET) imaging with magnetic resonance imaging (MRI) and photoacoustic (PA) imaging was successfully achieved. The promising results suggest the great potential of these nanoconjugates for multi-dimensional and more accurate tumor diagnosis and therapy in the future.

  16. Effects of soy hull pectin and insoluble fiber on physicochemical and oxidative characteristics of fresh and frozen/thawed beef patties.

    PubMed

    Kim, Hyun-Wook; Miller, Danika K; Lee, Yong Jae; Kim, Yuan H Brad

    2016-07-01

    The objective of this study was to determine the effects of pectin and insoluble fiber isolated from soy hulls on water-holding capacity (WHC), texture, color, and lipid oxidation of fresh and frozen/thawed beef patties. Beef patties were formulated with no dietary fiber (control), 1% soy hull pectin, insoluble fiber, or their mixture (1:1), respectively. The addition of soy hull pectin significantly decreased display weight loss and increased cook yield of both fresh and frozen/thawed beef patties. In addition, no significant difference in hardness between fresh and frozen/thawed beef patties was observed for all dietary fiber treatments. However, incorporation of insoluble soy hull fiber decreased color and lipid oxidation stabilities of both fresh and frozen/thawed beef patties. Our results indicate that the incorporation of soy hull pectin could be an effective non-meat ingredient to minimize water loss and hardness defects of frozen beef patties. PMID:26946478

  17. A process of applying polypyrrole-engineered pulp fibers prepared using hydrogen peroxide as oxidant to detoxification of Cr(VI)-contaminated water.

    PubMed

    Lei, Yu; Qian, Xueren; Shen, Jing; An, Xianhui

    2013-03-01

    In this study, different from previous reports, an alternative process for detoxification of Cr(VI)-contaminated water with polypyrrole-engineered pulp fibers prepared using low cost hydrogen peroxide as oxidant was proposed. The process conditions in preparation of the engineered fibers as well as the water treatment conditions were optimized, and the behavior of Cr desorption from the engineered fibers was evaluated. The results showed that the proposed process was highly efficient in Cr(VI)-detoxification via the integration of adsorption with reduction. Compared with the previously reported polyaniline-engineered fibers prepared with hydrogen peroxide as oxidant, the engineered fibers studied in this work was much more effective. PMID:23340110

  18. Carbon-fiber technology

    NASA Technical Reports Server (NTRS)

    Hansen, C. F.; Parker, J. A.

    1980-01-01

    The state of the art of PAN based carbon fiber manufacture and the science of fiber behavior is surveyed. A review is given of the stabilization by oxidation and the subsequent carbonization of fibers, of the apparent structure of fibers deduced from scanning electron microscopy, from X-ray scattering, and from similarities with soft carbons, and of the known relations between fiber properties and heat treatment temperature. A simplified model is invoked to explain the electrical properties of fibers and recent quantum chemical calculations on atomic clusters are used to elucidate some aspects of fiber conductivity. Some effects of intercalation and oxidative modification of finished fibers are summarized.

  19. Characterization of Niobium Oxide Films Deposited by High Target Utilization Sputter Sources

    SciTech Connect

    Chow, R; Ellis, A D; Loomis, G E; Rana, S I

    2007-01-29

    High quality, refractory metal, oxide coatings are required in a variety of applications such as laser optics, micro-electronic insulating layers, nano-device structures, electro-optic multilayers, sensors and corrosion barriers. A common oxide deposition technique is reactive sputtering because the kinetic mechanism vaporizes almost any solid material in vacuum. Also, the sputtered molecules have higher energies than those generated from thermal evaporation, and so the condensates are smoother and denser than those from thermally-evaporated films. In the typical sputtering system, target erosion is a factor that drives machine availability. In some situations such as nano-layered capacitors, where the device's performance characteristics depends on thick layers, target life becomes a limiting factor on the maximizing device functionality. The keen interest to increase target utilization in sputtering has been addressed in a variety of ways such as target geometry, rotating magnets, and/or shaped magnet arrays. Also, a recent sputtering system has been developed that generates a high density plasma, directs the plasma beam towards the target in a uniform fashion, and erodes the target in a uniform fashion. The purpose of this paper is to characterize and compare niobia films deposited by two types of high target utilization sputtering sources, a rotating magnetron and a high density plasma source. The oxide of interest in this study is niobia because of its high refractive index. The quality of the niobia films were characterized spectroscopically in optical transmission, ellipsometrically, and chemical stoichiometry with X-ray photo-electron spectroscopy. The refractive index, extinction coefficients, Cauchy constants were derived from the ellipsometric modeling. The mechanical properties of coating density and stress are also determined.

  20. Oxidation-specific epitopes as targets for biotheranostic applications in humans: Biomarkers, molecular imaging and therapeutics

    PubMed Central

    Miller, Yury I.; Tsimikas, Sotirios

    2014-01-01

    Purpose of Review Emerging data demonstrates the potential of translational applications of antibodies directed against oxidation-specific epitopes (OSE). “Biotheranostics” in cardiovascular disease (CVD) describes targeting of OSE for biomarker, therapeutic and molecular imaging diagnostic applications. Recent findings Lipid oxidation collectively yields a large variety of oxidation-specific epitopes (OSE), such as oxidized phospholipids (OxPL) and malondialdehyde (MDA) epitopes. OSE are immunogenic, pro-inflammatory, pro-atherogenic and plaque destabilizing and represent danger associated molecular patterns (DAMPs). DAMPs are recognized by the innate immune system via pattern recognition receptors, including scavenger receptors IgM natural antibodies and complement factor H (CFH), that bind, neutralize and/or facilitate their clearance. Biomarker assays measuring OxPL present on apolipoprotein B-100 lipoproteins, and particularly on lipoprotein (a), predict the development of CVD events. In contrast, OxPL on plasminogen facilitate fibrinolysis and may reduce atherothrombosis. Oxidation-specific antibodies (OSA) attached to magnetic nanoparticles image lipid-rich, oxidation-rich plaques. Infusion or overexpression of OSA reduces the progression of atherosclerosis, suggesting that they may be used in similar applications in humans. Summary Using the accelerating knowledge base and improved understanding of the interplay of oxidation, inflammation and innate and adaptive immunity in atherogenesis, emerging clinical applications of OSA may identify, monitor and treat CVD in humans. PMID:23995232

  1. Chitin-glucan fiber effects on oxidized low-density lipoprotein: a randomized controlled trial

    PubMed Central

    Bays, H E; Evans, J L; Maki, K C; Evans, M; Maquet, V; Cooper, R; Anderson, J W

    2013-01-01

    Background/objectives: Elevated oxidized low-density lipoprotein (OxLDL) may promote inflammation, and is associated with increased risk of atherosclerotic coronary heart disease and worsening complications of diabetes mellitus. The primary objective of this study was to evaluate the efficacy of chitin-glucan (CG), alone and in combination with a potentially anti-inflammatory olive oil (OO) extract, for reducing OxLDL in subjects with borderline to high LDL cholesterol (LDL-C) levels. Subjects/methods: This 6-week, randomized, double-blind, placebo-controlled study of a novel, insoluble fiber derived from the Aspergillus niger mycelium, CG, evaluated 130 subjects free of diabetes mellitus with fasting LDL-C 3.37–4.92 mmol/l and glucose ⩽6.94 mmol/l. Participants were randomly assigned to receive CG (4.5 g/day; n=33), CG (1.5 g/day; n=32), CG (1.5 g/day) plus OO extract (135 mg/day; n=30), or matching placebo (n=35). Results: Administration of 4.5 g/day CG for 6 weeks significantly reduced OxLDL compared with placebo (P=0.035). At the end of study, CG was associated with lower LDL-C levels relative to placebo, although this difference was statistically significant only for the CG 1.5 g/day group (P=0.019). CG did not significantly affect high-density lipoprotein cholesterol, triglycerides, glucose, insulin or F2-isoprostane levels. Adverse events did not substantively differ between treatments and placebo. Conclusions: In this 6-week study, CG (4.5 g/day) reduced OxLDL, an effect that might affect the risk for atherosclerosis. PMID:22948945

  2. Preparation of silica-sustained electrospun polyvinylpyrrolidone fibers with uniform mesopores via oxidative removal of template molecules by H{sub 2}O{sub 2} treatment

    SciTech Connect

    Kang, Haigang; Zhu, Yihua; Shen, Jianhua; Yang, Xiaoling; Chen, Cheng; Cao, Huimin; Li, Chungzhong

    2010-07-15

    Silica-sustained electrospun PVP fibers with uniform mesopores were synthesized via facile oxidative removal of template molecules by H{sub 2}O{sub 2} extraction. Tetraethyl orthosilicate, polyvinylpyrrolidone (PVP), and triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer pluronic P{sub 123} compose the electrospinning sol to fabricate the silica-sustained PVP hybrid fibers. The effect of different post-treatment methods on the pore size distribution was investigated by calcination and extraction, respectively. Experimental results showed that oxidative removal of structure-directing agent P{sub 123} in the hybrid fibers by H{sub 2}O{sub 2} treatment can easily form narrow pore size distribution, and the incorporation of 3D silica skeleton built by hot steam aging facilitated preserving the original cylindrical morphology of fibers. Scanning electron microscopy (SEM), N{sub 2} adsorption-desorption isotherm, transmission electron microscopy (TEM), X-ray diffraction (XRD), FT-IR spectra and thermogravimetric analysis (TGA) were used to characterize the hybrid fibers. The hybrid fibers can be expected to have potential applications in drug release or tissue engineering because of their suitable pore size, large surface area and good biocompatibility.

  3. Targeting the Ataxia Telangiectasia Mutated-null phenotype in chronic lymphocytic leukemia with pro-oxidants

    PubMed Central

    Agathanggelou, Angelo; Weston, Victoria J.; Perry, Tracey; Davies, Nicholas J.; Skowronska, Anna; Payne, Daniel T.; Fossey, John S.; Oldreive, Ceri E.; Wei, Wenbin; Pratt, Guy; Parry, Helen; Oscier, David; Coles, Steve J.; Hole, Paul S.; Darley, Richard L.; McMahon, Michael; Hayes, John D.; Moss, Paul; Stewart, Grant S.; Taylor, A. Malcolm R.; Stankovic, Tatjana

    2015-01-01

    Inactivation of the Ataxia Telangiectasia Mutated gene in chronic lymphocytic leukemia results in resistance to p53-dependent apoptosis and inferior responses to treatment with DNA damaging agents. Hence, p53-independent strategies are required to target Ataxia Telangiectasia Mutated-deficient chronic lymphocytic leukemia. As Ataxia Telangiectasia Mutated has been implicated in redox homeostasis, we investigated the effect of the Ataxia Telangiectasia Mutated-null chronic lymphocytic leukemia genotype on cellular responses to oxidative stress with a view to therapeutic targeting. We found that in comparison to Ataxia Telangiectasia Mutated-wild type chronic lymphocytic leukemia, pro-oxidant treatment of Ataxia Telangiectasia Mutated-null cells led to reduced binding of NF-E2 p45-related factor-2 to antioxidant response elements and thus decreased expression of target genes. Furthermore, Ataxia Telangiectasia Mutated-null chronic lymphocytic leukemia cells contained lower levels of antioxidants and elevated mitochondrial reactive oxygen species. Consequently, Ataxia Telangiectasia Mutated-null chronic lymphocytic leukemia, but not tumors with 11q deletion or TP53 mutations, exhibited differentially increased sensitivity to pro-oxidants both in vitro and in vivo. We found that cell death was mediated by a p53- and caspase-independent mechanism associated with apoptosis inducing factor activity. Together, these data suggest that defective redox-homeostasis represents an attractive therapeutic target for Ataxia Telangiectasia Mutated-null chronic lymphocytic leukemia. PMID:25840602

  4. Gel spinning of PVA composite fibers with high content of multi-walled carbon nanotubes and graphene oxide hybrids

    NASA Astrophysics Data System (ADS)

    Wei, Yizhe; Lai, Dengpan; Zou, Liming; Ling, Xinlong; Lu, Hongwei; Xu, Yongjing

    2015-07-01

    In this report, poly (vinyl alcohol) (PVA) composite fibers with high content of multi-walled carbon nanotubes and graphene oxide (MWCNTs-GO) hybrids were prepared by gel spinning, and were characterized by TGA, DSC, SEM, XL-2 yarn strength tester and electrical conductivity measurement. The total content of MWCNTs-GO hybrids in the PVA composite fibers, which is up to 25 wt%, was confirmed by TGA analysis. The DSC measurement shows that the melting and crystallization peaks decreased after the addition of nano-fillers. This is due to the reason that the motion of PVA chains is completely confined by strong hydrogen bonding interaction between PVA and nano-fillers. After the addtion of GO, the dispersibility of MWCNTs in composite fibers improved slightly. And the tensile strength and Young's modulus increased by 38% and 67%, respectively. This is caused by the increased hydrogen bonding interaction and synergistic effect through hybridization of MWCNTs and GO. More significantly, the electrical conductivity of PVA/MWCNTs/GO composite fibers enhanced by three orders of magnitude with the addition of GO.

  5. Novel method for fabrication of metal- or oxide-nanoparticle doped silica-based specialty optical fibers

    NASA Astrophysics Data System (ADS)

    Lenardič, Borut; Kveder, Miha; Lisjak, Darja; Guillon, Herve; Bonnafous, Samuel

    2011-03-01

    Nanoparticle-doped optical fibers are causing significant scientific interest in different application fields. Nanoparticle-doping of silica glass layers during optical fiber preform fabrication was so far reported by sol-gel and solution doping processes, by flame hydrolysis spraying and by pulling hollow cylinders from nanoparticle suspensions. A new method for fabrication of high quality nanoparticle-doped fibers is suggested. Proposed method is based on "flash vaporization" deposition process, previously reported as method to fabricate rare earth- and metal ion-doped specialty optical fibers. Experiments were made where SiO2 layers were deposited using "flash vaporization"-equipped MCVD system, adding vapors carrying metal or oxide nanoparticles into deposition zone. Analysis of produced preforms confirms presence of nanoparticles in deposited layers, albeit with low deposition rate due to weak thermophoretic forces acting on very small particles or agglomerations. Based on results, a number of improvements were suggested and implemented in fabrication process, device design and choice of precursor materials. "Flash vaporization" method was demonstrated as suitable method for deposition of nanoparticles in silica layers, permitting in-situ fabrication of complete preforms, providing easy upgrade path for existing MCVD and OVD deposition systems and allowing simultaneous co-doping by a wide range of other co-dopants.

  6. Effect of Cattle Breed on Meat Quality, Muscle Fiber Characteristics, Lipid Oxidation and Fatty Acids in China

    PubMed Central

    Xie, Xiangxue; Meng, Qingxiang; Cui, Zhenliang; Ren, Liping

    2012-01-01

    The objective was to compare meat quality, muscle fiber characteristics, lipid oxidation and fatty acids of Limousin (LIM), Simmtental (SIM), Luxi (LX), Qinchuan (QC) and Jinnan (JN) offered the same diet in China. After finishing, eight bulls from each breed were randomly selected for slaughter at 18.5 months old. Longissimus dorsi (ld) muscle was taken from the carcass for meat quality evaluations. Breed had little effect on most of meat and fat color parameters except for Hue and b* in which QC had lower values. LIM showed higher pH (24 h) and better water holding capacity than other breeds. LIM showed the lowest dry matter content but the highest crude protein. LX and LIM had higher percentage and density of red muscle fiber than other breeds. Lipid oxidations were significantly lower in LIM than in QC, with the LX, SIM and JN having the intermediate values. Compared to other four breeds, QC provided the highest values of polyunsaturated fatty acids (PUFA), n-6 fatty acids and n-3 fatty acids. In conclusion, LIM scored better on most of meat quality characteristics; however, local breeds such as LX and QC also had better muscle fiber characteristics and better fatty acids composition. PMID:25049633

  7. Changes of nitric oxide synthase-containing nerve fibers and parameters for oxidative stress after unilateral cavernous nerve resection or manuplation in rat penis.

    PubMed

    Ozkara, Hamdi; Alan, Cabir; Atukeren, Pinar; Uyaner, Ilhan; Demirci, Cihan; Gümüştaş, M Koray; Alici, Bulent

    2006-06-30

    After pelvic surgeries such as radical prostatectomy, two major complications--urinary incontinence and erectile dysfunction (ED) may occur. Etiologies for ED are multiple pathologic mediators/systems. Oxidative stress, which is known to be induced after surgical trauma, could be a cause of ED. The purposes of in this study are to investigate the effect of unilateral manipulation/ dissection and resection of the cavernous nerve (neurotomy) to NOS (nitric oxide synthase)-containing nerve fibers and pressure after electro stimulation in rat corpus cavernosum, and to determine whether these procedures would produce oxidative stress within rat cavernous tissue 3 weeks and 6 months after the operation. Male rats were divided into 5 groups. Rats in groups 1 and 2 underwent unilateral cavernous nerve manipulation and sacrificed 3 weeks and 6 months after the operation, respectively. Rats in groups 3 and 4 underwent unilateral neurotomy of a 5-mm. segment of the cavernous nerve, and they were sacrificed 3 weeks and 6 months after nerve ablation, respectively. Group 5 rats were control animals for biochemical analysis. Intracavernous pressure following electro stimulation reduced is significantly 3 weeks after unilateral resection, as compared to that of the manipulated nerve (P < 0.05), and it recovered 6 months after neurotomy. The recovery was also confirmed by NADPH (nicotinamide adenine dinucleotide phosphate) diaphorase staining in neurotomy groups. Lipid peroxidation, which is an indicater of oxidative stress, was determined by measuring thiobarbituric acid reacting substance (TBARS) levels and superoxide dismutase (SOD) activity. These markers indicated that unilateral cavernous nerve manipulation or resection produced oxidative stress within rat corpus cavernosum. Oxidative stress was more prominent 3 weeks after unilateral neurotomy (P < 0.05). Also, compared to the control animal group, oxidative stress was observed three weeks after manipulation of unilateral

  8. The intellectual disability gene Kirrel3 regulates target-specific mossy fiber synapse development in the hippocampus

    PubMed Central

    Martin, E Anne; Muralidhar, Shruti; Wang, Zhirong; Cervantes, Diégo Cordero; Basu, Raunak; Taylor, Matthew R; Hunter, Jennifer; Cutforth, Tyler; Wilke, Scott A; Ghosh, Anirvan; Williams, Megan E

    2015-01-01

    Synaptic target specificity, whereby neurons make distinct types of synapses with different target cells, is critical for brain function, yet the mechanisms driving it are poorly understood. In this study, we demonstrate Kirrel3 regulates target-specific synapse formation at hippocampal mossy fiber (MF) synapses, which connect dentate granule (DG) neurons to both CA3 and GABAergic neurons. Here, we show Kirrel3 is required for formation of MF filopodia; the structures that give rise to DG-GABA synapses and that regulate feed-forward inhibition of CA3 neurons. Consequently, loss of Kirrel3 robustly increases CA3 neuron activity in developing mice. Alterations in the Kirrel3 gene are repeatedly associated with intellectual disabilities, but the role of Kirrel3 at synapses remained largely unknown. Our findings demonstrate that subtle synaptic changes during development impact circuit function and provide the first insight toward understanding the cellular basis of Kirrel3-dependent neurodevelopmental disorders. DOI: http://dx.doi.org/10.7554/eLife.09395.001 PMID:26575286

  9. The intellectual disability gene Kirrel3 regulates target-specific mossy fiber synapse development in the hippocampus

    PubMed Central

    Martin, E Anne; Muralidhar, Shruti; Wang, Zhirong; Cervantes, Diégo Cordero; Basu, Raunak; Taylor, Matthew R; Hunter, Jennifer; Cutforth, Tyler; Wilke, Scott A; Ghosh, Anirvan; Williams, Megan E

    2015-01-01

    Synaptic target specificity, whereby neurons make distinct types of synapses with different target cells, is critical for brain function, yet the mechanisms driving it are poorly understood. In this study, we demonstrate Kirrel3 regulates target-specific synapse formation at hippocampal mossy fiber (MF) synapses, which connect dentate granule (DG) neurons to both CA3 and GABAergic neurons. Here, we show Kirrel3 is required for formation of MF filopodia; the structures that give rise to DG-GABA synapses and that regulate feed-forward inhibition of CA3 neurons. Consequently, loss of Kirrel3 robustly increases CA3 neuron activity in developing mice. Alterations in the Kirrel3 gene are repeatedly associated with intellectual disabilities, but the role of Kirrel3 at synapses remained largely unknown. Our findings demonstrate that subtle synaptic changes during development impact circuit function and provide the first insight toward understanding the cellular basis of Kirrel3-dependent neurodevelopmental disorders. DOI: http://dx.doi.org/10.7554/eLife.09395.001

  10. Identifying initial molecular targets of PDT: protein and lipid oxidation products

    NASA Astrophysics Data System (ADS)

    Oleinick, Nancy L.; Kim, Junhwan; Rodriguez, Myriam E.; Xue, Liang-yan; Kenney, Malcolm E.; Anderson, Vernon E.

    2009-06-01

    Photodynamic Therapy (PDT) generates singlet oxygen (1O2) which oxidizes biomolecules in the immediate vicinity of its formation. The phthalocyanine photosensitizer Pc 4 localizes to mitochondria and endoplasmic reticulum, and the primary targets of Pc 4-PDT are expected to be lipids and proteins of those membranes. The initial damage then causes apoptosis in cancer cells via the release of cytochrome c (Cyt-c) from mitochondria into the cytosol, followed by the activation of caspases. That damage also triggers the induction of autophagy, an attempt by the cells to eliminate damaged organelles, or when damage is too extensive, to promote cell death. Cyt-c is bound to the cytosolic side of the mitochondrial inner membrane through association with cardiolipin (CL), a phospholipid containing four unsaturated fatty acids and thus easily oxidized by 1O2 or by other oxidizing agents. Increasing evidence suggests that oxidation of CL loosens its association with Cyt-c, and that the peroxidase activity of Cyt-c can oxidize CL. In earlier studies of Cyt-c in homogeneous medium by MALDI-TOF-MS and LC-ESI-MS, we showed that 1O2 generated by Pc 4-PDT oxidized histidine, methionine, tryptophan, and unexpectedly phenylalanine but not tyrosine. Most of the oxidation products were known to be formed by other oxidizing agents, such as hydroxyl radical, superoxide radical anion, and peroxynitrite. However, two products of histidine were unique to 1O2 and may be useful for reporting the action of 1O2 in cells and tissues. These products, as well as CL oxidation products, have now been identified in liposomes and mitochondria after Pc 4-PDT. In mitochondria, the PDT dose-dependent oxidations can be related to specific changes in mitochondrial function, Bcl-2 photodamage, and Cyt-c release. Thus, the role of PDT-generated 1O2 in oxidizing Cyt-c and CL and the interplay between protein and lipid targets may be highly relevant to understanding one mechanism for cell killing by PDT.

  11. CHIRON TOOLS: Integrated Target Submission, Scheduling and Observing Systems for a High-Resolution Fiber-Fed Spectrograph

    NASA Astrophysics Data System (ADS)

    Brewer, John M.; Giguere, Matthew; Fischer, Debra A.

    2014-01-01

    The CHIRON spectrometer is a new high-resolution, fiber-fed instrument on the 1.5 m telescope at Cerro Tololo Inter-America Observatory (CTIO). To optimize use of the instrument and limited human resources, we have designed an integrated set of Web applications allowing target submission, observing script planning, nightly script execution and logging, and access to reduced data by multiple users. The unified and easy-to-use interface has dramatically reduced the time needed to submit and schedule observations and improved the efficiency and accuracy of nightly operations. We present our experience to help astronomers and project managers who need to plan for the scope of effort required to commission a queue-scheduled facility instrument.

  12. Gold nanoparticle-conjugated anti-oxidized low-density lipoprotein antibodies for targeted lipidomics of oxidative stress biomarkers.

    PubMed

    Hinterwirth, Helmut; Stübiger, Gerald; Lindner, Wolfgang; Lämmerhofer, Michael

    2013-09-01

    Oxidized low-density lipoproteins (OxLDLs), in particular, oxidized phosphatidylcholines (OxPCs), are known to be involved in pathophysiological processes such as cardiovascular diseases and are described as potential biomarkers, for example, for atherosclerosis. In our study, we used the specific affinity of anti-OxLDL antibodies (Abs) conjugated to gold nanoparticles (GNPs) for extraction and enrichment of OxPCs via selective trapping of OxLDLs from plasma combined with the sensitive detection by liquid chromatography/tandem-mass spectrometry (LC-MS/MS). Successful bioconjugation chemistry of Abs via a bifunctional polyethylene glycol (PEG) spacer and protein G linkage, respectively, was controlled by measuring the surface plasmon resonance (SPR) spectra, size, and zeta potentials. Furthermore, the amount of Ab immobilized onto GNP via the PEG linker was determined. With the optimized immobilization chemistry, the ability and potential of the GNP-based extraction procedure was used for the determination of the dissociation constant, K(d), of the OxLDL binding to the GNP-Ab conjugate. Moreover, apparent K(d)'s were determined for individual PCs and their oxidation products using the compound-specific selected reaction monitoring mode, which allows the characterization of the Ab affinity and, thus, assessment of the potential antigenicity of (Ox)PCs bound to OxLDLs. In summary, the application of GNP-based bioanalysis for selective targeting of OxLDLs and the fast and sensitive detection by LC-MS/MS offers new possibilities for targeted lipidomics in lipoproteins as well as for oxidative stress lipid biomarker screening. PMID:23895666

  13. Alumina fiber strength improvement

    NASA Technical Reports Server (NTRS)

    Pepper, R. T.; Nelson, D. C.

    1982-01-01

    The effective fiber strength of alumina fibers in an aluminum composite was increased to 173,000 psi. A high temperature heat treatment, combined with a glassy carbon surface coating, was used to prevent degradation and improve fiber tensile strength. Attempts to achieve chemical strengthening of the alumina fiber by chromium oxide and boron oxide coatings proved unsuccessful. A major problem encountered on the program was the low and inconsistent strength of the Dupont Fiber FP used for the investigation.

  14. Nitric oxide and reactive oxygen species: Clues to target oxidative damage repair defective breast cancers.

    PubMed

    Somasundaram, Veena; Nadhan, Revathy; K Hemalatha, Sreelatha; Kumar Sengodan, Satheesh; Srinivas, Priya

    2016-05-01

    The identification of various biomolecules in cancer progression and therapy has led to the exploration of the roles of two cardinal players, namely Nitric Oxide (NO) and Reactive Oxygen Species (ROS) in cancer. Both ROS and NO display bimodal fashions of functional activity in a concentration dependent manner, by inducing either pro- or anti- tumorigenic signals. Researchers have identified the potential capability of NO and ROS in therapies owing to their role in eliciting pro-apoptotic signals at higher concentrations and their ability to sensitize cancer cells to one another as well as to other therapeutics. We review the prospects of NO and ROS in cancer progression and therapy, and analyze the role of a combinatorial therapy wherein an NO donor (SNAP) is used to sensitize the oxidative damage repair defective, triple negative breast cancer cells (HCC 1937) to a potent ROS inducer. Preliminary findings support the potential to employ various combinatorial regimes for anti-cancer therapies with regard to exploiting the chemo-sensitization property of NO donors. PMID:27017408

  15. Periodontitis in Rats Induces Systemic Oxidative Stress That Is Controlled by Bone-Targeted Antiresorptives

    PubMed Central

    Oktay, Sehkar; Chukkapalli, Sasanka S.; Rivera-Kweh, Mercedes F.; Velsko, Irina M.; Holliday, L. Shannon; Kesavalu, Lakshmyya

    2015-01-01

    Background Periodontitis is a chronic, polymicrobial inflammatory disease that degrades connective tissue and alveolar bone and results in tooth loss. Oxidative stress has been linked to the onset of periodontal tissue breakdown and systemic inflammation, and the success of antiresorptive treatments will rely on how effectively they can ameliorate periodontal disease–induced oxidative stress during oral infection. Methods Rats were infected with polybacterial inoculum consisting of Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, as an oral lavage every other week for 12 weeks. Daily subcutaneous injections of enoxacin, bisenoxacin, alendronate, or doxycycline were administered for 6 weeks after 6 weeks of polybacterial infection in rats. The serum levels of oxidative stress parameters and antioxidant enzymes, including glutathione peroxidase, superoxide dismutase, and catalase, were evaluated in each of the infected, treated, and sham-infected rats. Results Rats infected with the periodontal pathogens displayed a five-fold increase in the oxidative stress index compared with controls as a result of increased levels of serum oxidants and decreases in total antioxidant activity. The overall decrease in antioxidant activity occurred despite increases in three important antioxidant enzymes, suggesting an imbalance between antioxidant macromolecules/small molecules production and antioxidant enzyme levels. Surprisingly, the bone-targeted antiresorptives bis-enoxacin and alendronate inhibited increases in oxidative stress caused by periodontitis. Bis-enoxacin, which has both antiresorptive and antibiotic activities, was more effective than alendronate, which acts only as an antiresorptive. Conclusion To the best of the authors’ knowledge, this is the first study to demonstrate that the increased oxidative stress induced by periodontal infection in rats can be ameliorated by bone-targeted antiresorptives. PMID:25101489

  16. Curcumin targeting the thioredoxin system elevates oxidative stress in HeLa cells

    SciTech Connect

    Cai, Wenqing; Zhang, Baoxin; Duan, Dongzhu; Wu, Jincai; Fang, Jianguo

    2012-08-01

    The thioredoxin system, composed of thioredoxin reductase (TrxR), thioredoxin (Trx), and NADPH, is ubiquitous in all cells and involved in many redox-dependent signaling pathways. Curcumin, a naturally occurring pigment that gives a specific yellow color in curry food, is consumed in normal diet up to 100 mg per day. This molecule has also been used in traditional medicine for the treatment of a variety of diseases. Curcumin has numerous biological functions, and many of these functions are related to induction of oxidative stress. However, how curcumin elicits oxidative stress in cells is unclear. Our previous work has demonstrated the way by which curcumin interacts with recombinant TrxR1 and alters the antioxidant enzyme into a reactive oxygen species (ROS) generator in vitro. Herein we reported that curcumin can target the cytosolic/nuclear thioredoxin system to eventually elevate oxidative stress in HeLa cells. Curcumin-modified TrxR1 dose-dependently and quantitatively transfers electrons from NADPH to oxygen with the production of ROS. Also, curcumin can drastically down-regulate Trx1 protein level as well as its enzyme activity in HeLa cells, which in turn remarkably decreases intracellular free thiols, shifting the intracellular redox balance to a more oxidative state, and subsequently induces DNA oxidative damage. Furthermore, curcumin-pretreated HeLa cells are more sensitive to oxidative stress. Knockdown of TrxR1 sensitizes HeLa cells to curcumin cytotoxicity, highlighting the physiological significance of targeting TrxR1 by curcumin. Taken together, our data disclose a previously unrecognized prooxidant mechanism of curcumin in cells, and provide a deep insight in understanding how curcumin works in vivo. -- Highlights: ► Curcumin induces oxidative stress by targeting the thioredoxin system. ► Curcumin-modified TrxR quantitatively oxidizes NADPH to generate ROS. ► Knockdown of TrxR1 augments curcumin's cytotoxicity in HeLa cells. ► Curcumin

  17. Mitochondrial targeting of bilirubin regulatory enzymes: An adaptive response to oxidative stress

    SciTech Connect

    Muhsain, Siti Nur Fadzilah; Lang, Matti A.; Abu-Bakar, A'edah

    2015-01-01

    The intracellular level of bilirubin (BR), an endogenous antioxidant that is cytotoxic at high concentrations, is tightly controlled within the optimal therapeutic range. We have recently described a concerted intracellular BR regulation by two microsomal enzymes: heme oxygenase 1 (HMOX1), essential for BR production and cytochrome P450 2A5 (CYP2A5), a BR oxidase. Herein, we describe targeting of these enzymes to hepatic mitochondria during oxidative stress. The kinetics of microsomal and mitochondrial BR oxidation were compared. Treatment of DBA/2J mice with 200 mg pyrazole/kg/day for 3 days increased hepatic intracellular protein carbonyl content and induced nucleo-translocation of Nrf2. HMOX1 and CYP2A5 proteins and activities were elevated in microsomes and mitoplasts but not the UGT1A1, a catalyst of BR glucuronidation. A CYP2A5 antibody inhibited 75% of microsomal BR oxidation. The inhibition was absent in control mitoplasts but elevated to 50% after treatment. An adrenodoxin reductase antibody did not inhibit microsomal BR oxidation but inhibited 50% of mitochondrial BR oxidation. Ascorbic acid inhibited 5% and 22% of the reaction in control and treated microsomes, respectively. In control mitoplasts the inhibition was 100%, which was reduced to 50% after treatment. Bilirubin affinity to mitochondrial and microsomal CYP2A5 enzyme is equally high. Lastly, the treatment neither released cytochrome c into cytoplasm nor dissipated membrane potential, indicating the absence of mitochondrial membrane damage. Collectively, the observations suggest that BR regulatory enzymes are recruited to mitochondria during oxidative stress and BR oxidation by mitochondrial CYP2A5 is supported by mitochondrial mono-oxygenase system. The induced recruitment potentially confers membrane protection. - Highlights: • Pyrazole induces oxidative stress in the mouse liver. • Pyrazole-induced oxidative stress induces mitochondrial targeting of key bilirubin regulatory enzymes, HMOX1

  18. Zinc oxide nanoparticle-doped nanoporous solgel fiber as a humidity sensor with enhanced sensitivity and large linear dynamic range.

    PubMed

    Aneesh, R; Khijwania, Sunil K

    2013-08-01

    An all-optical humidity sensor based on direct and exhaustive guided-mode attenuation in an in-house developed zinc oxide (ZnO) nanoparticle-immobilized bare solgel fiber is reported. The main objective of the present work is to enhance the sensitivity considerably while realizing a throughout linear response over a wide dynamic range. The developed sensor is characterized and performance characteristics of the sensor are compared with an optical fiber humidity sensor employing an evanescent wave absorption scheme in a straight and uniform probe, with ZnO nanoparticles-immobilized solgel film as humidity sensing cladding. Sensor response is observed to be linear over a wide dynamic range of 5%-95% relative humidity (RH). The observed linear sensitivity is 0.0103/% RH, which is ~9 times higher than the sensor employing the evanescent wave absorption scheme. In addition, sensor response is observed to be very fast, highly reversible, and repeatable. PMID:23913070

  19. Arginase: The Emerging Therapeutic Target for Vascular Oxidative Stress and Inflammation

    PubMed Central

    Yang, Zhihong; Ming, Xiu-Fen

    2013-01-01

    Oxidative stress and inflammation in the vascular wall are essential mechanisms of atherosclerosis and vascular dysfunctions associated with risk factors such as metabolic diseases, aging, hypertension, etc. Evidence has been provided that activation of the vascular endothelial cells in the presence of the risk factors promotes oxidative stress and vascular inflammatory responses, leading to acceleration of atherosclerotic vascular disease. Increasing number of studies from recent years demonstrates that uncoupling of endothelial nitric oxide synthase (eNOS), whereby the enzyme eNOS produces detrimental amount of superoxide anion O2− instead the vasoprotective nitric oxide (NO⋅), plays a critical role in vascular dysfunction under various pathophysiological conditions and in aging. The mechanisms of eNOS-uncoupling seem multiple and complex. Recent research provides emerging evidence supporting an essential role of increased activity of arginases including arginase-I and arginase-II in causing eNOS-uncoupling, which results in vascular oxidative stress and inflammatory responses, and ultimately leading to vascular diseases. This review article will summarize the most recent findings on the functional roles of arginases in vascular diseases and/or dysfunctions and the underlying mechanisms in relation to oxidative stress and inflammations. Moreover, regulatory mechanisms of arginases in the vasculature are reviewed and the future perspectives of targeting arginases as therapeutic options in vascular diseases are discussed. PMID:23781221

  20. Experimental and theoretical studies on localized surface plasmon resonance based fiber optic sensor using graphene oxide coated silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Nayak, Jeeban Kumar; Parhi, Purnendu; Jha, Rajan

    2016-07-01

    An optical fiber based refractive index sensor using graphene oxide (GO) encapsulated silver nanoparticles (AgNPs) is reported. The AgNPs are encapsulated with a very thin layer of GO as it controls the inter-particle distance thereby preventing aggregation. The encapsulation also enhances the colloidal stability and prevents the oxidation of the AgNPs by separating them from direct contact with the aqueous medium. High-resolution transmission electron microscopy results support the formation of 1 nm thick GO around AgNPs of an average size of 35 nm. A Raman spectrometer and a UV–VIS spectrometer have been used to characterize and study the synthesized nanoparticles along with GO. Further, Raman spectra support a 64.72% increase in D-peak intensity and a 52.91% increase in G-peak intensity of the GO-encapsulated AgNPs (GOE-AgNPs) with respect to GO. Further, the GOE-AgNPs are immobilized on the core of functionalized plastic-cladded silica fiber. FESEM confirms the immobilization of the GOE-AgNPs on the fiber core. We observed that the peak absorbance changes by 87.55% with a 0.05 change in the refractive index. The sensitivity of the proposed fiber sensor is found to be 0.9406 ΔA/RIU along with a resolution of 12.8  ×  {{10}-4} RIU. MATLAB is used to calculate the absorbance of the AgNPs by considering the bound and free electron contribution along with the size-dependent dispersion of the nanoparticles. We found that the simulation results are in good agreement with the experimental results.

  1. 1,4-Dihydropyridine Derivatives: Dihydronicotinamide Analogues—Model Compounds Targeting Oxidative Stress

    PubMed Central

    Velena, Astrida; Zarkovic, Neven; Gall Troselj, Koraljka; Bisenieks, Egils; Krauze, Aivars; Poikans, Janis; Duburs, Gunars

    2016-01-01

    Many 1,4-dihydropyridines (DHPs) possess redox properties. In this review DHPs are surveyed as protectors against oxidative stress (OS) and related disorders, considering the DHPs as specific group of potential antioxidants with bioprotective capacities. They have several peculiarities related to antioxidant activity (AOA). Several commercially available calcium antagonist, 1,4-DHP drugs, their metabolites, and calcium agonists were shown to express AOA. Synthesis, hydrogen donor properties, AOA, and methods and approaches used to reveal biological activities of various groups of 1,4-DHPs are presented. Examples of DHPs antioxidant activities and protective effects of DHPs against OS induced damage in low density lipoproteins (LDL), mitochondria, microsomes, isolated cells, and cell cultures are highlighted. Comparison of the AOA of different DHPs and other antioxidants is also given. According to the data presented, the DHPs might be considered as bellwether among synthetic compounds targeting OS and potential pharmacological model compounds targeting oxidative stress important for medicinal chemistry. PMID:26881016

  2. Daunomycin-loaded superparamagnetic iron oxide nanoparticles: Preparation, magnetic targeting, cell cytotoxicity, and protein delivery research.

    PubMed

    Liu, Min-Chao; Jin, Shu-Fang; Zheng, Min; Wang, Yan; Zhao, Peng-Liang; Tang, Ding-Tong; Chen, Jiong; Lin, Jia-Qi; Wang, Xia-Hong; Zhao, Ping

    2016-08-01

    The clinical use of daunomycin is restricted by dose-dependent toxicity and low specificity against cancer cells. In the present study, modified superparamagnetic iron oxide nanoparticles were employed to load daunomycin and the drug-loaded nanospheres exhibited satisfactory size and smart pH-responsive release. The cellular uptake efficiency, targeted cell accumulation, and cell cytotoxicity experimental results proved that the superparamagnetic iron oxide nanoparticle-loading process brings high drug targeting without decreasing the cytotoxicity of daunomycin. Moreover, a new concern for the evaluation of nanophase drug delivery's effects was considered, with monitoring the interactions between human serum albumin and the drug-loaded nanospheres. Results from the multispectroscopic techniques and molecular modeling calculation elucidate that the drug delivery has detectable deleterious effects on the frame conformation of protein, which may affect its physiological function. PMID:27288463

  3. 1,4-Dihydropyridine Derivatives: Dihydronicotinamide Analogues-Model Compounds Targeting Oxidative Stress.

    PubMed

    Velena, Astrida; Zarkovic, Neven; Gall Troselj, Koraljka; Bisenieks, Egils; Krauze, Aivars; Poikans, Janis; Duburs, Gunars

    2016-01-01

    Many 1,4-dihydropyridines (DHPs) possess redox properties. In this review DHPs are surveyed as protectors against oxidative stress (OS) and related disorders, considering the DHPs as specific group of potential antioxidants with bioprotective capacities. They have several peculiarities related to antioxidant activity (AOA). Several commercially available calcium antagonist, 1,4-DHP drugs, their metabolites, and calcium agonists were shown to express AOA. Synthesis, hydrogen donor properties, AOA, and methods and approaches used to reveal biological activities of various groups of 1,4-DHPs are presented. Examples of DHPs antioxidant activities and protective effects of DHPs against OS induced damage in low density lipoproteins (LDL), mitochondria, microsomes, isolated cells, and cell cultures are highlighted. Comparison of the AOA of different DHPs and other antioxidants is also given. According to the data presented, the DHPs might be considered as bellwether among synthetic compounds targeting OS and potential pharmacological model compounds targeting oxidative stress important for medicinal chemistry. PMID:26881016

  4. Unchanged content of oxidative enzymes in fast-twitch muscle fibers and kinetics after intensified training in trained cyclists

    PubMed Central

    Christensen, Peter M; Gunnarsson, Thomas P; Thomassen, Martin; Wilkerson, Daryl P; Nielsen, Jens Jung; Bangsbo, Jens

    2015-01-01

    The present study examined if high intensity training (HIT) could increase the expression of oxidative enzymes in fast-twitch muscle fibers causing a faster oxygen uptake () response during intense (INT), but not moderate (MOD), exercise and reduce the slow component and muscle metabolic perturbation during INT. Pulmonary kinetics was determined in eight trained male cyclists (-max: 59 ± 4 (means ± SD) mL min−1 kg−1) during MOD (205 ± 12 W ∼65% -max) and INT (286 ± 17 W ∼85% -max) exercise before and after a 7-week HIT period (30-sec sprints and 4-min intervals) with a 50% reduction in volume. Both before and after HIT the content in fast-twitch fibers of CS (P < 0.05) and COX-4 (P < 0.01) was lower, whereas PFK was higher (P < 0.001) than in slow-twitch fibers. Content of CS, COX-4, and PFK in homogenate and fast-twitch fibers was unchanged with HIT. Maximal activity (μmol g DW−1 min−1) of CS (56 ± 8 post-HIT vs. 59 ± 10 pre-HIT), HAD (27 ± 6 vs. 29 ± 3) and PFK (340 ± 69 vs. 318 ± 105) and the capillary to fiber ratio (2.30 ± 0.16 vs. 2.38 ± 0.20) was unaltered following HIT. kinetics was unchanged with HIT and the speed of the primary response did not differ between MOD and INT. Muscle creatine phosphate was lower (42 ± 15 vs. 66 ± 17 mmol kg DW−1) and muscle lactate was higher (40 ± 18 vs. 14 ± 5 mmol kg DW−1) at 6 min of INT (P < 0.05) after compared to before HIT. A period of intensified training with a volume reduction did not increase the content of oxidative enzymes in fast-twitch fibers, and did not change kinetics. PMID:26152692

  5. Synthesis and Evaluation of Folate-Conjugated Phenanthraquinones for Tumor-Targeted Oxidative Chemotherapy

    PubMed Central

    Kumar, Ajay; Chelvam, Venkatesh; Sakkarapalayam, Mahalingam; Li, Guo; Sanchez-Cruz, Pedro; Piñero, Natasha S.; Low, Philip S.; Alegria, Antonio E.

    2016-01-01

    Almost all cells are easily killed by exposure to potent oxidants. Indeed, major pathogen defense mechanisms in both animal and plant kingdoms involve production of an oxidative burst, where host defense cells show an invading pathogen with reactive oxygen species (ROS). Although cancer cells can be similarly killed by ROS, development of oxidant-producing chemotherapies has been limited by their inherent nonspecificity and potential toxicity to healthy cells. In this paper, we describe the targeting of an ROS-generating molecule selectively to tumor cells using folate as the tumor-targeting ligand. For this purpose, we exploit the ability of 9,10-phenanthraquinone (PHQ) to enhance the continuous generation of H2O2 in the presence of ascorbic acid to establish a constitutive source of ROS within the tumor mass. We report here that incubation of folate receptor-expressing KB cells in culture with folate-PHQ plus ascorbate results in the death of the cancer cells with an IC50 of ~10 nM (folate-PHQ). We also demonstrate that a cleavable spacer linking folate to PHQ is significantly inferior to a noncleavable spacer, in contrast to most other folate-targeted therapeutic agents. Unfortunately, no evidence for folate-PHQ mediated tumor regression in murine tumor models is obtained, suggesting that unanticipated impediments to generation of cytotoxic quantities of ROS in vivo are encountered. Possible mechanisms and potential solutions to these unanticipated results are offered. PMID:27066312

  6. Pathogenesis of Target Organ Damage in Hypertension: Role of Mitochondrial Oxidative Stress

    PubMed Central

    Rubattu, Speranza; Pagliaro, Beniamino; Pierelli, Giorgia; Santolamazza, Caterina; Di Castro, Sara; Mennuni, Silvia; Volpe, Massimo

    2014-01-01

    Hypertension causes target organ damage (TOD) that involves vasculature, heart, brain and kidneys. Complex biochemical, hormonal and hemodynamic mechanisms are involved in the pathogenesis of TOD. Common to all these processes is an increased bioavailability of reactive oxygen species (ROS). Both in vitro and in vivo studies explored the role of mitochondrial oxidative stress as a mechanism involved in the pathogenesis of TOD in hypertension, especially focusing on atherosclerosis, heart disease, renal failure, cerebrovascular disease. Both dysfunction of mitochondrial proteins, such as uncoupling protein-2 (UCP2), superoxide dismutase (SOD) 2, peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α), calcium channels, and the interaction between mitochondria and other sources of ROS, such as NADPH oxidase, play an important role in the development of endothelial dysfunction, cardiac hypertrophy, renal and cerebral damage in hypertension. Commonly used anti-hypertensive drugs have shown protective effects against mitochondrial-dependent oxidative stress. Notably, few mitochondrial proteins can be considered therapeutic targets on their own. In fact, antioxidant therapies specifically targeted at mitochondria represent promising strategies to reduce mitochondrial dysfunction and related hypertensive TOD. In the present article, we discuss the role of mitochondrial oxidative stress as a contributing factor to hypertensive TOD development. We also provide an overview of mitochondria-based treatment strategies that may reveal useful to prevent TOD and reduce its progression. PMID:25561233

  7. Continuous Fiber Ceramic Composites (CFCC)

    SciTech Connect

    R. A. Wagner

    2002-12-18

    This report summarizes work to develop CFCC's for various applications in the Industries of the Future (IOF) and power generation areas. Performance requirements range from relatively modest for hot gas filters to severe for turbine combustor liners and infrared burners. The McDermott Technology Inc. (MTI) CFCC program focused on oxide/oxide composite systems because they are known to be stable in the application environments of interest. The work is broadly focused on dense and porous composite systems depending on the specific application. Dense composites were targeted at corrosion resistant components, molten aluminum handling components and gas turbine combustor liners. The development work on dense composites led to significant advances in fiber coatings for oxide fibers and matrix densification. Additionally, a one-step fabrication process was developed to produce low cost composite components. The program also supported key developments in advanced oxide fibers that resulted in an improved version of Nextel 610 fiber (commercially available as Nextel 650) and significant progress in the development of a YAG/alumina fiber. Porous composite development focused on the vacuum winding process used to produce hot gas filters and infrared burner components.

  8. Fiber optic hydrogen gas sensor utilizing surface plasmon resonance and native defects of zinc oxide by palladium

    NASA Astrophysics Data System (ADS)

    Tabassum, Rana; Gupta, Banshi D.

    2016-01-01

    We present an experimental study on a surface plasmon resonance (SPR) based fiber optic hydrogen gas sensor employing a palladium doped zinc oxide nanocomposite (ZnO(1-x)Pd x , 0 ≤ x ≤ 0.85) layer over the silver coated unclad core of the fiber. Palladium doped zinc oxide nanocomposites (ZnO(1-x)Pd x ) are prepared by a chemical route for different composition ratios and their structural, morphological and hydrogen sensing properties are investigated experimentally. The sensing principle involves the absorption of hydrogen gas by ZnO(1-x)Pd x , altering its dielectric function. The change in the dielectric constant is analyzed in terms of the red shift of the resonance wavelength in the visible region of the electromagnetic spectrum. To check the sensing capability of sensing probes fabricated with varying composition ratio (x) of nanocomposite, the SPR curves are recorded typically for 0% H2 and 4% H2 in N2 atmosphere for each fabricated probe. On changing the concentration of hydrogen gas from 0% to 4%, the red shift in the SPR spectrum confirms the change in dielectric constant of ZnO(1-x)Pd x on exposure to hydrogen gas. It is noted that the shift in the SPR spectrum increases monotonically up to a certain fraction of Pd in zinc oxide, beyond which it starts decreasing. SEM images and the photoluminescence (PL) spectra reveal that Pd dopant atoms substitutionally incorporated into the ZnO lattice profoundly affect its defect levels; this is responsible for the optimal composition of ZnO(1-x)Pd x to sense the hydrogen gas. The sensor is highly selective to hydrogen gas and possesses high sensitivity. Since optical fiber sensing technology is employed along with the SPR technique, the present sensor is capable of remote sensing and online monitoring of hydrogen gas.

  9. Curcumin targeting the thioredoxin system elevates oxidative stress in HeLa cells.

    PubMed

    Cai, Wenqing; Zhang, Baoxin; Duan, Dongzhu; Wu, Jincai; Fang, Jianguo

    2012-08-01

    The thioredoxin system, composed of thioredoxin reductase (TrxR), thioredoxin (Trx), and NADPH, is ubiquitous in all cells and involved in many redox-dependent signaling pathways. Curcumin, a naturally occurring pigment that gives a specific yellow color in curry food, is consumed in normal diet up to 100mg per day. This molecule has also been used in traditional medicine for the treatment of a variety of diseases. Curcumin has numerous biological functions, and many of these functions are related to induction of oxidative stress. However, how curcumin elicits oxidative stress in cells is unclear. Our previous work has demonstrated the way by which curcumin interacts with recombinant TrxR1 and alters the antioxidant enzyme into a reactive oxygen species (ROS) generator in vitro. Herein we reported that curcumin can target the cytosolic/nuclear thioredoxin system to eventually elevate oxidative stress in HeLa cells. Curcumin-modified TrxR1 dose-dependently and quantitatively transfers electrons from NADPH to oxygen with the production of ROS. Also, curcumin can drastically down-regulate Trx1 protein level as well as its enzyme activity in HeLa cells, which in turn remarkably decreases intracellular free thiols, shifting the intracellular redox balance to a more oxidative state, and subsequently induces DNA oxidative damage. Furthermore, curcumin-pretreated HeLa cells are more sensitive to oxidative stress. Knockdown of TrxR1 sensitizes HeLa cells to curcumin cytotoxicity, highlighting the physiological significance of targeting TrxR1 by curcumin. Taken together, our data disclose a previously unrecognized prooxidant mechanism of curcumin in cells, and provide a deep insight in understanding how curcumin works in vivo. PMID:22634334

  10. Zinc oxide nanowire interphase for enhanced interfacial strength in lightweight polymer fiber composites.

    PubMed

    Ehlert, Gregory J; Sodano, Henry A

    2009-08-01

    A novel functionalization method for aramid fibers is developed to enhance the bonding of a ZnO nanowire interphase grown on the fiber surface for interfacial strength enhancement. The nanowire interphase functionally grades the typically discrete interface and reduces the stress concentration between the fiber and matrix. The functionalization process is developed to improve the bonding between the ZnO nanowires and the aramid fiber and is validated through Fourier transform IR and X-ray photoelectron spectroscopy studies. Mechanical testing shows significant improvement in the interfacial shear strength with no decrease in the base fiber strength. This is the only technique found in the literature for the growth of a nanowire interphase on polymer fibers for structural enhancement without degrading the in-plane properties of the bulk composite. Furthermore, it is firmly shown that the functionalization process is a necessary condition for enhanced interfacial strength, demonstrating that ZnO nanowires strongly interact with carboxylic acid functional groups. PMID:20355800