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Sample records for carbon content niti

  1. Improvement on corrosion resistance of NiTi orthopedic materials by carbon plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    Poon, Ray W. Y.; Ho, Joan P. Y.; Luk, Camille M. Y.; Liu, Xuanyong; Chung, Jonathan C. Y.; Chu, Paul K.; Yeung, Kelvin W. K.; Lu, William W.; Cheung, Kenneth M. C.

    2006-01-01

    Nickel-titanium shape memory alloys (NiTi) have potential applications as orthopedic implants because of their unique super-elastic properties and shape memory effects. However, the problem of out-diffusion of harmful Ni ions from the alloys during prolonged use inside a human body must be overcome before they can be widely used in orthopedic implants. In this work, we enhance the corrosion resistance of NiTi using carbon plasma immersion ion implantation and deposition (PIII&D). Our corrosion and simulated body fluid tests indicate that either an ion-mixed amorphous carbon coating fabricated by PIII&D or direct carbon PIII can drastically improve the corrosion resistance and block the out-diffusion of Ni from the materials. Results of atomic force microscopy (AFM) indicate that both C2H2-PIII&D and C2H2-PIII do not roughen the original flat surface to an extent that can lead to degradation in corrosion resistance.

  2. Microstructure, mechanical properties and superelasticity of biomedical porous NiTi alloy prepared by microwave sintering.

    PubMed

    Xu, J L; Bao, L Z; Liu, A H; Jin, X J; Tong, Y X; Luo, J M; Zhong, Z C; Zheng, Y F

    2015-01-01

    Porous NiTi alloys were prepared by microwave sintering using ammonium hydrogen carbonate (NH4HCO3) as the space holder agent to adjust the porosity in the range of 22-62%. The effects of porosities on the microstructure, hardness, compressive strength, bending strength, elastic modulus, phase transformation temperature and superelasticity of the porous NiTi alloys were investigated. The results showed that the porosities and average pore sizes of the porous NiTi alloys increased with increasing the contents of NH4HCO3. The porous NiTi alloys consisted of nearly single NiTi phase, with a very small amount of two secondary phases (Ni3Ti, NiTi2) when the porosities are lower than 50%. The amount of Ni3Ti and NiTi2 phases increased with further increasing of the porosity proportion. The porosities had few effects on the phase transformation temperatures of the porous NiTi alloys. By increasing the porosities, all of the hardness, compressive strength, elastic modulus, bending strength and superelasticity of the porous NiTi alloys decreased. However, the compressive strength and bending strength were higher or close to those of natural bone and the elastic modulus was close to the natural bone. The superelastic recovery strain of the trained porous NiTi alloys could reach between 3.1 and 4.7% at the pre-strain of 5%, even if the porosity was up to 62%. Moreover, partial shape memory effect was observed for all porosity levels under the experiment conditions. Therefore, the microwave sintered porous NiTi alloys could be a promising candidate for bone implant.

  3. Reproducibility Study of NiTi Parts Made by Metal Injection Molding

    NASA Astrophysics Data System (ADS)

    Bram, M.; Bitzer, M.; Buchkremer, H. P.; Stöver, D.

    2012-12-01

    Powder metallurgy (P/M) is an attractive manufacturing process for net-shaped NiTi parts considering the limited machinability of NiTi alloys. Nevertheless, the industrial implementation of P/M processing for NiTi alloys is not trivial. To become competitive to manufacturing of NiTi alloys based on established ingot metallurgy, combination of fully pronounced shape memory behavior with sufficient mechanical properties is required. Successful use of P/M technology is strongly influenced by high affinity of NiTi alloys for uptake of oxygen and carbon, which leads to the formation of oxygen-containing Ti2Ni and TiC phases coupled with increase of Ni content in the matrix. In the case of Ni-rich NiTi alloys, this increase leads to a shift of phase transformation temperatures to lower values. Furthermore, precipitation of Ni4Ti3 during cooling from sintering temperature is difficult to avoid. Even if these precipitates might be used to decrease the Ni:Ti ratio of the matrix balancing oxygen and carbon uptake, significant loss of ductility arises, especially in the case of finely dispersed Ni4Ti3 precipitates. In the present work, each step of P/M manufacturing is discussed regarding its influence on the specific properties of NiTi alloys. The work is based on the application of prealloyed, gas atomized NiTi powders. Metal injection molding was used for net-shaped manufacturing of tensile samples, which enabled detailed study of sintering behavior combined with investigation of shape memory and mechanical properties depending on particle size, oxygen and carbon content as well as precipitation of Ni4Ti3 phase.

  4. Characterization of mechanical properties of hydroxyapatite-silicon-multi walled carbon nano tubes composite coatings synthesized by EPD on NiTi alloys for biomedical application.

    PubMed

    Khalili, Vida; Khalil-Allafi, Jafar; Sengstock, Christina; Motemani, Yahya; Paulsen, Alexander; Frenzel, Jan; Eggeler, Gunther; Köller, Manfred

    2016-06-01

    Release of Ni(1+) ions from NiTi alloy into tissue environment, biological response on the surface of NiTi and the allergic reaction of atopic people towards Ni are challengeable issues for biomedical application. In this study, composite coatings of hydroxyapatite-silicon multi walled carbon nano-tubes with 20wt% Silicon and 1wt% multi walled carbon nano-tubes of HA were deposited on a NiTi substrate using electrophoretic methods. The SEM images of coated samples exhibit a continuous and compact morphology for hydroxyapatite-silicon and hydroxyapatite-silicon-multi walled carbon nano-tubes coatings. Nano-indentation analysis on different locations of coatings represents the highest elastic modulus (45.8GPa) for HA-Si-MWCNTs which is between the elastic modulus of NiTi substrate (66.5GPa) and bone tissue (≈30GPa). This results in decrease of stress gradient on coating-substrate-bone interfaces during performance. The results of nano-scratch analysis show the highest critical distance of delamination (2.5mm) and normal load before failure (837mN) as well as highest critical contact pressure for hydroxyapatite-silicon-multi walled carbon nano-tubes coating. The cell culture results show that human mesenchymal stem cells are able to adhere and proliferate on the pure hydroxyapatite and composite coatings. The presence of both silicon and multi walled carbon nano-tubes (CS3) in the hydroxyapatite coating induce more adherence of viable human mesenchymal stem cells in contrast to the HA coated samples with only silicon (CS2). These results make hydroxyapatite-silicon-multi walled carbon nano-tubes a promising composite coating for future bone implant application. PMID:26897095

  5. Characterization of mechanical properties of hydroxyapatite-silicon-multi walled carbon nano tubes composite coatings synthesized by EPD on NiTi alloys for biomedical application.

    PubMed

    Khalili, Vida; Khalil-Allafi, Jafar; Sengstock, Christina; Motemani, Yahya; Paulsen, Alexander; Frenzel, Jan; Eggeler, Gunther; Köller, Manfred

    2016-06-01

    Release of Ni(1+) ions from NiTi alloy into tissue environment, biological response on the surface of NiTi and the allergic reaction of atopic people towards Ni are challengeable issues for biomedical application. In this study, composite coatings of hydroxyapatite-silicon multi walled carbon nano-tubes with 20wt% Silicon and 1wt% multi walled carbon nano-tubes of HA were deposited on a NiTi substrate using electrophoretic methods. The SEM images of coated samples exhibit a continuous and compact morphology for hydroxyapatite-silicon and hydroxyapatite-silicon-multi walled carbon nano-tubes coatings. Nano-indentation analysis on different locations of coatings represents the highest elastic modulus (45.8GPa) for HA-Si-MWCNTs which is between the elastic modulus of NiTi substrate (66.5GPa) and bone tissue (≈30GPa). This results in decrease of stress gradient on coating-substrate-bone interfaces during performance. The results of nano-scratch analysis show the highest critical distance of delamination (2.5mm) and normal load before failure (837mN) as well as highest critical contact pressure for hydroxyapatite-silicon-multi walled carbon nano-tubes coating. The cell culture results show that human mesenchymal stem cells are able to adhere and proliferate on the pure hydroxyapatite and composite coatings. The presence of both silicon and multi walled carbon nano-tubes (CS3) in the hydroxyapatite coating induce more adherence of viable human mesenchymal stem cells in contrast to the HA coated samples with only silicon (CS2). These results make hydroxyapatite-silicon-multi walled carbon nano-tubes a promising composite coating for future bone implant application.

  6. Variable carbon contents of lunar soil 74220

    NASA Technical Reports Server (NTRS)

    Gibson, E. K., Jr.; Moore, C. B.

    1973-01-01

    Total carbon, sulfur, and inorganic gas release studies have been carried out on an additional split of orange soil 74220. The total carbon content was found to be 4 plus or minus 3 ppm C for this sample as compared to an earlier reported value of 100 plus or minus 10 ppm C. Gas release studies on the two splits of 74220 indicate that the carbon may be present as a surface condensate on the sample showing the higher carbon content. The 'surface condensate' evolves CO2 upon heating to temperatures below 400 C.

  7. Preparing hydroxyapatite-silicon composite suspensions with homogeneous distribution of multi-walled carbon nano-tubes for electrophoretic coating of NiTi bone implant and their effect on the surface morphology

    NASA Astrophysics Data System (ADS)

    Khalili, Vida; Khalil-Allafi, Jafar; Xia, Wei; Parsa, Alireza B.; Frenzel, Jan; Somsen, Christoph; Eggeler, Gunther

    2016-03-01

    Preparing a stable suspension is a main step towards the electrophoretically depositing of homogeneous and dense composite coatings on NiTi for its biomedical application. In the present study, different composite suspensions of hydroxyapatite, silicon and multi-walled carbon nano-tubes were prepared using n-butanol and triethanolamine as media and dispersing agent, respectively. Multi-walled carbon nanotubes were first functionalized in the nitric acid vapor for 15 h at 175 °C, and then mixed into suspensions. Thermal desorption spectroscopy profiles indicate the formation of functional groups on multi-walled carbon nano-tubes. An excellent suspension stability can be achieved for different amounts of triethanolamine. The amount of triethanolamine can be increased by adding a second component to a stable hydroxyapatite suspension due to an electrostatic interaction between components in suspension. The stability of composite suspension is less than that of the hydroxyapatite suspension, due to density differences, which under the gravitational force promote the demixing. The scanning electron microscopy images of the coatings surface show that more dense coatings are developed on NiTi substrate using electrophoretic deposition and sintering at 850 °C in the simultaneous presence of silicon and multi-walled carbon nanotubes in the hydroxyapatite coatings. The atomic force microscopy results of the coatings surface represent that composite coatings of hydroxyapatite-20 wt.% silicon and hydroxyapatite-20 wt.% silicon-1 wt.% multi-walled carbon nano-tubes with low zeta potential have rougher surfaces.

  8. Carbon fiber content measurement in composite

    NASA Astrophysics Data System (ADS)

    Wang, Qiushi

    Carbon fiber reinforced polymers (CFRPs) have been widely used in various structural applications in industries such as aerospace and automotive because of their high specific stiffness and specific strength. Their mechanical properties are strongly influenced by the carbon fiber content in the composites. Measurement of the carbon fiber content in CFRPs is essential for product quality control and process optimization. In this work, a novel carbonization-in-nitrogen method (CIN) is developed to characterize the fiber content in carbon fiber reinforced thermoset and thermoplastic composites. In this method, a carbon fiber composite sample is carbonized in a nitrogen environment at elevated temperatures, alongside a neat resin sample. The carbon fibers are protected from oxidization while the resin (the neat resin and the resin matrix in the composite sample) is carbonized under the nitrogen environment. The residue of the carbonized neat resin sample is used to calibrate the resin carbonization rate and calculate the amount of the resin matrix in the composite sample. The new method has been validated on several thermoset and thermoplastic resin systems and found to yield an accurate measurement of fiber content in carbon fiber polymer composites. In order to further understand the thermal degradation behavior of the high temperature thermoplastic polymer during the carbonization process, the mechanism and the kinetic model of thermal degradation behavior of carbon fiber reinforced poly (phenylene sulfide) (CPPS) are studied using thermogravimetry analysis (TGA). The CPPS is subjected to TGA in an air and nitrogen atmosphere at heating rates from 5 to 40°C min--1. The TGA curves obtained in air are different from those in nitrogen. This demonstrates that weight loss occurs in a single stage in nitrogen but in two stages in air. To elucidate this difference, thermal decomposition kinetics is analyzed by applying the Kissinger, Flynn-Wall-Ozawa, Coat-Redfern and

  9. Determination of the carbon content of airborne fungal spores.

    PubMed

    Bauer, Heidi; Kasper-Giebl, Anne; Zibuschka, Franziska; Hitzenberger, Regina; Kraus, Gunther F; Puxbaum, Hans

    2002-01-01

    Airborne fungal spores contribute potentially to the organic carbon of the atmospheric aerosol, mainly in the "coarse aerosol" size range 2.5-10 microm aerodynamic equivalent diameter (aed). Here, we report about a procedure to determine the organic carbon content of fungal spores frequently observed in the atmosphere. Furthermore, we apply a new (carbon/individual) factor to quantify the amount of fungal-spores-derived organic carbon in aerosol collected at a mountain site in Austria. Spores of representatives of Cladosporium sp., Aspergillus sp., Penicillium sp., and Alternaria sp., the four predominant airborne genera, were analyzed for their carbon content using two different analytical procedures. The result was an average carbon content of 13 pg C/spore (RSD, 46%), or expressed as a carbon-per-volume ratio, 0.38 pg C/microm3 (RSD, 30%). These values are comparable to conversion factors for bacteria and some representatives of the zooplankton. Because biopolymers are suspected of interfering with elemental carbon determination by thermal methods, the amount of "fungal carbon" that might be erroneously mistaken for soot carbon was determined using the "two-step combustion" method of Cachier et al. and termed as "apparent elemental carbon" (AEC). This fraction amounted to up to 46% of the initial fungal carbon content. Although the aerosol samples were collected in March under wintry conditions, the organic carbon from fungal spores amounted to 2.9-5.4% of organic carbon in the "coarse mode" size fraction.

  10. Bone formation ability of carbonate apatite-collagen scaffolds with different carbonate contents.

    PubMed

    Matsuura, Ayumu; Kubo, Takayasu; Doi, Kazuya; Hayashi, Kazuhiko; Morita, Kouji; Yokota, Rie; Hayashi, Hidetaka; Hirata, Isao; Okazaki, Masayuki; Akagawa, Yasumasa

    2009-03-01

    Hydroxyapatite and carbonate apatites with different carbonate contents were synthesized, mixed with atelocollagen, and made into sponge scaffolds. The scaffolds were implanted into the bone sockets of the femurs of male New Zealand white rabbits for 2, 3, 12 and 24 weeks. carbonate apatite-collagen scaffold with 4.8 wt% carbonate content appeared to have similar crystallinity and chemical composition to human bone. When the scaffolds were implanted into the rabbit femurs, histological observation indicated that the carbonate apatites-collagen scaffolds with relatively higher carbonate contents were gradually deformed throughout the implantation period, and showed uniform surrounding bone after 24 weeks and could not be distinguished. The carbonate apatite-collagen scaffold with 4.8 wt% carbonate content showed the highest bone area ratio of all of the scaffolds. It is suggested that a carbonate apatite-collagen scaffold with carbonate content similar to that of human bone may have optimal bone formation ability.

  11. Effect of nano-hydroxyapatite reinforcement in mechanically alloyed NiTi composites for biomedical implant.

    PubMed

    Akmal, Muhammad; Raza, Ahmad; Khan, Muhammad Mudasser; Khan, M Imran; Hussain, Muhammad Asif

    2016-11-01

    Equi-atomic NiTi alloy composites reinforced with 0, 2, 4 and 6vol.% nano-hydroxyapatite (HA) were successfully synthesized using pressureless sintering. Pure Ni and Ti elements were ball milled for 10h in order to produce a mechanically alloyed equi-atomic NiTi alloy (MA-NiTi). Mechanically alloyed NiTi and HA powders were blended, compacted and then sintered for 3h at 1325K. The sintered density varied inversely with volume percent of HA reinforcement. The X-Ray diffraction spectra and SEM images showed the formation of multiple phases like NiTi, NiTi2, Ni3Ti, and Ni4Ti3. The back scattered-SEM image analysis confirmed the presence of Ni-rich and Ti-rich phases with increasing HA content. The 6vol.% HA reinforced composite showed Ni3Ti as the major phase having the highest hardness value which can be attributed to the presence of relatively harder phases along with higher HA content as a reinforcement. The composite of MA-NiTi with 2vol.% HA manifested the most desirable results in the form of better sintering density mainly due to the minute decomposition of NiTi into other phases. Therefore, the 2vol.% reinforced MA-NiTi composite can be exploited as a novel material for manufacturing biomedical implants.

  12. Effect of nano-hydroxyapatite reinforcement in mechanically alloyed NiTi composites for biomedical implant.

    PubMed

    Akmal, Muhammad; Raza, Ahmad; Khan, Muhammad Mudasser; Khan, M Imran; Hussain, Muhammad Asif

    2016-11-01

    Equi-atomic NiTi alloy composites reinforced with 0, 2, 4 and 6vol.% nano-hydroxyapatite (HA) were successfully synthesized using pressureless sintering. Pure Ni and Ti elements were ball milled for 10h in order to produce a mechanically alloyed equi-atomic NiTi alloy (MA-NiTi). Mechanically alloyed NiTi and HA powders were blended, compacted and then sintered for 3h at 1325K. The sintered density varied inversely with volume percent of HA reinforcement. The X-Ray diffraction spectra and SEM images showed the formation of multiple phases like NiTi, NiTi2, Ni3Ti, and Ni4Ti3. The back scattered-SEM image analysis confirmed the presence of Ni-rich and Ti-rich phases with increasing HA content. The 6vol.% HA reinforced composite showed Ni3Ti as the major phase having the highest hardness value which can be attributed to the presence of relatively harder phases along with higher HA content as a reinforcement. The composite of MA-NiTi with 2vol.% HA manifested the most desirable results in the form of better sintering density mainly due to the minute decomposition of NiTi into other phases. Therefore, the 2vol.% reinforced MA-NiTi composite can be exploited as a novel material for manufacturing biomedical implants. PMID:27523992

  13. Effects of Ni content on the shape memory properties and microstructure of Ni-rich NiTi-20Hf alloys

    NASA Astrophysics Data System (ADS)

    Saghaian, S. M.; Karaca, H. E.; Tobe, H.; Pons, J.; Santamarta, R.; Chumlyakov, Y. I.; Noebe, R. D.

    2016-09-01

    Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti29.3Hf20, Ni51.2Ti28.8Hf20, and Ni52Ti28Hf20 (at.%)) were systematically characterized in the furnace cooled condition. H-phase precipitates were formed during furnace cooling in compositions with greater than 50.3Ni and the driving force for nucleation increased with Ni content. Alloy strength increased while recoverable strain decreased with increasing Ni content due to changes in precipitate characteristics. When the precipitates were small (˜5-15 nm), they were readily absorbed by martensite plates, which resulted in maximum recoverable strain of 2% in Ni50.7Ti29.3Hf20. With increasing Ni content, the size (>100 nm) and volume fraction of precipitates increased and the growth of martensite plates was constrained between the precipitates when the Ni concentration was greater than 50.7 at.%. Near perfect dimensional stability with negligible irrecoverable strain was observed at stress levels as high as 2 GPa in the Ni52Ti28Hf20 alloy, though the recoverable strain was rather small. In general, strong local stress fields were created at precipitate/matrix interphases, which lead to high stored elastic energy during the martensitic transformation.

  14. Effects of Ni content on the shape memory properties and microstructure of Ni-rich NiTi-20Hf alloys

    NASA Astrophysics Data System (ADS)

    Saghaian, S. M.; Karaca, H. E.; Tobe, H.; Pons, J.; Santamarta, R.; Chumlyakov, Y. I.; Noebe, R. D.

    2016-09-01

    Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti29.3Hf20, Ni51.2Ti28.8Hf20, and Ni52Ti28Hf20 (at.%)) were systematically characterized in the furnace cooled condition. H-phase precipitates were formed during furnace cooling in compositions with greater than 50.3Ni and the driving force for nucleation increased with Ni content. Alloy strength increased while recoverable strain decreased with increasing Ni content due to changes in precipitate characteristics. When the precipitates were small (∼5–15 nm), they were readily absorbed by martensite plates, which resulted in maximum recoverable strain of 2% in Ni50.7Ti29.3Hf20. With increasing Ni content, the size (>100 nm) and volume fraction of precipitates increased and the growth of martensite plates was constrained between the precipitates when the Ni concentration was greater than 50.7 at.%. Near perfect dimensional stability with negligible irrecoverable strain was observed at stress levels as high as 2 GPa in the Ni52Ti28Hf20 alloy, though the recoverable strain was rather small. In general, strong local stress fields were created at precipitate/matrix interphases, which lead to high stored elastic energy during the martensitic transformation.

  15. Tensile deformation of NiTi wires.

    PubMed

    Gall, Ken; Tyber, Jeff; Brice, Valerie; Frick, Carl P; Maier, Hans J; Morgan, Neil

    2005-12-15

    We examine the structure and properties of cold drawn Ti-50.1 at % Ni and Ti-50.9 at % Ni shape memory alloy wires. Wires with both compositions possess a strong <111> fiber texture in the wire drawing direction, a grain size on the order of micrometers, and a high dislocation density. The more Ni rich wires contain fine second phase precipitates, while the wires with lower Ni content are relatively free of precipitates. The wire stress-strain response depends strongly on composition through operant deformation mechanisms, and cannot be explained based solely on measured differences in the transformation temperatures. We provide fundamental connections between the material structure, deformation mechanisms, and resulting stress-strain responses. The results help clarify some inconsistencies and common misconceptions in the literature. Ramifications on materials selection and design for emerging biomedical applications of NiTi shape memory alloys are discussed.

  16. Magical NiTi expander

    PubMed Central

    Katti, Chandrika Girish; Katti, Girish; Kallur, Ravi; Ghali, Srinivas Rao

    2013-01-01

    A 24-year-old male patient was referred to our department for expansion of the constricted maxillary arch as a presurgical procedure for the correction of congenital facial disfigurement. On examination, the patient had a convex profile, increased interlabial gap, tongue thrust, limited mouth opening, posterior crossbite, asymmetric ‘V’-shaped maxillary arch with severe constriction, crowding of anterior teeth in the maxillary arch and a massive open bite. Radiographic investigations included orthopantomograph and occlusal radiographs. The patient photographs and models were analysed. On careful evaluation, the treatment for maxillary arch expansion was planned with a nickel titanium (NiTi) slow maxillary expander along with fixed mechanotherapy for alignment of teeth. An unexpectedly successful outcome was appreciated from the treatment. An emphasis should be laid on selecting and treating the case of constricted arches with a surgical or non-surgical approach, as expansion can be achieved orthodontically by using NiTi expanders. PMID:23867876

  17. Porous NiTi shape memory alloys produced by SHS: microstructure and biocompatibility in comparison with Ti2Ni and TiNi3.

    PubMed

    Bassani, Paola; Panseri, Silvia; Ruffini, Andrea; Montesi, Monica; Ghetti, Martina; Zanotti, Claudio; Tampieri, Anna; Tuissi, Ausonio

    2014-10-01

    Shape memory alloys based on NiTi have found their main applications in manufacturing of new biomedical devices mainly in surgery tools, stents and orthopedics. Porous NiTi can exhibit an engineering elastic modulus comparable to that of cortical bone (12-17 GPa). This condition, combined with proper pore size, allows good osteointegration. Open cells porous NiTi was produced by self propagating high temperature synthesis (SHS), starting from Ni and Ti mixed powders. The main NiTi phase is formed during SHS together with other Ni-Ti compounds. The biocompatibility of such material was investigated by single culture experiment and ionic release on small specimen. In particular, NiTi and porous NiTi were evaluated together with elemental Ti and Ni reference metals and the two intermetallic TiNi3, Ti2Ni phases. This approach permitted to clearly identify the influence of secondary phases in porous NiTi materials and relation with Ni-ion release. The results indicated, apart the well-known high toxicity of Ni, also toxicity of TiNi3, whilst phases with higher Ti content showed high biocompatibility. A slightly reduced biocompatibility of porous NiTi was ascribed to combined effect of TiNi3 presence and topography that requires higher effort for the cells to adapt to the surface.

  18. Porous NiTi shape memory alloys produced by SHS: microstructure and biocompatibility in comparison with Ti2Ni and TiNi3.

    PubMed

    Bassani, Paola; Panseri, Silvia; Ruffini, Andrea; Montesi, Monica; Ghetti, Martina; Zanotti, Claudio; Tampieri, Anna; Tuissi, Ausonio

    2014-10-01

    Shape memory alloys based on NiTi have found their main applications in manufacturing of new biomedical devices mainly in surgery tools, stents and orthopedics. Porous NiTi can exhibit an engineering elastic modulus comparable to that of cortical bone (12-17 GPa). This condition, combined with proper pore size, allows good osteointegration. Open cells porous NiTi was produced by self propagating high temperature synthesis (SHS), starting from Ni and Ti mixed powders. The main NiTi phase is formed during SHS together with other Ni-Ti compounds. The biocompatibility of such material was investigated by single culture experiment and ionic release on small specimen. In particular, NiTi and porous NiTi were evaluated together with elemental Ti and Ni reference metals and the two intermetallic TiNi3, Ti2Ni phases. This approach permitted to clearly identify the influence of secondary phases in porous NiTi materials and relation with Ni-ion release. The results indicated, apart the well-known high toxicity of Ni, also toxicity of TiNi3, whilst phases with higher Ti content showed high biocompatibility. A slightly reduced biocompatibility of porous NiTi was ascribed to combined effect of TiNi3 presence and topography that requires higher effort for the cells to adapt to the surface. PMID:24928669

  19. Jellyfish Body Plans Provide Allometric Advantages beyond Low Carbon Content

    PubMed Central

    Pitt, Kylie A.; Duarte, Carlos M.; Lucas, Cathy H.; Sutherland, Kelly R.; Condon, Robert H.; Mianzan, Hermes; Purcell, Jennifer E.; Robinson, Kelly L.; Uye, Shin-Ichi

    2013-01-01

    Jellyfish form spectacular blooms throughout the world’s oceans. Jellyfish body plans are characterised by high water and low carbon contents which enables them to grow much larger than non-gelatinous animals of equivalent carbon content and to deviate from non-gelatinous pelagic animals when incorporated into allometric relationships. Jellyfish have, however, been argued to conform to allometric relationships when carbon content is used as the metric for comparison. Here we test the hypothesis that differences in allometric relationships for several key functional parameters remain for jellyfish even after their body sizes are scaled to their carbon content. Data on carbon and nitrogen contents, rates of respiration, excretion, growth, longevity and swimming velocity of jellyfish and other pelagic animals were assembled. Allometric relationships between each variable and the equivalent spherical diameters of jellyfish and other pelagic animals were compared before and after sizes of jellyfish were standardised for their carbon content. Before standardisation, the slopes of the allometric relationships for respiration, excretion and growth were the same for jellyfish and other pelagic taxa but the intercepts differed. After standardisation, slopes and intercepts for respiration were similar but excretion rates of jellyfish were 10× slower, and growth rates 2× faster than those of other pelagic animals. Longevity of jellyfish was independent of size. The slope of the allometric relationship of swimming velocity of jellyfish differed from that of other pelagic animals but because they are larger jellyfish operate at Reynolds numbers approximately 10× greater than those of other pelagic animals of comparable carbon content. We conclude that low carbon and high water contents alone do not explain the differences in the intercepts or slopes of the allometric relationships of jellyfish and other pelagic animals and that the evolutionary longevity of jellyfish and

  20. Effect of Graphitic Content on Carbon Supported Catalyst Performance

    SciTech Connect

    A. Patel; K. Artyushkova; P. Atanassov; David Harvey; M. Dutta; V. Colbow; S. Wessel

    2011-07-01

    The effect of graphitic content on carbon supported platinum catalysts was investigated in order to investigate its influence on catalyst performance. Four catalysts of varying surface areas and graphitic content were analyzed using XPS, HREELS, and tested using RDE experiments. The catalysts were also heat treated at 150 C and 100%RH as means to uniformly age them. The heat treated samples were analyzed using the same methods to determine what changes had occurred due to this aging process. When compared to the BOL catalysts, heat treated catalysts displayed increased graphitic carbon and platinum metallic content, however they also showed depressed catalytic activity. The primary cause is still under investigation, though it is believed to be related to loss of amorphous carbon content.

  1. Effect of Graphitic Content on Carbon Supported Catalyst Performance

    SciTech Connect

    Patel, Anant; Artyushkova, Kateryna; Atanassov, Plamen; Harvey, David; Dutta, Monica; Colbow, Vesna

    2011-07-01

    The effect of graphitic content on carbon supported platinum catalysts was investigated in order to investigate its influence on catalyst performance. Four catalysts of varying surface areas and graphitic content were analyzed using XPS, HREELS, and tested using RDE experiments. The catalysts were also heat treated at 150oC and 100%RH as means to uniformly age them. The heat treated samples were analyzed using the same methods to determine what changes had occurred due to this aging process. When compared to the BOL catalysts, heat treated catalysts displayed increased graphitic carbon and platinum metalic content, however they also showed depressed catalytic activity. The primary cause is still under investigation, though it is believed to be related to loss of amorphous carbon content.

  2. Characterization and corrosion study of NiTi laser surface alloyed with Nb or Co

    NASA Astrophysics Data System (ADS)

    Ng, K. W.; Man, H. C.; Yue, T. M.

    2011-02-01

    The interest in NiTi alloys for medical applications has been steadily growing in recent years because of its biocompatibility, superelasticity and shape memory characteristics. However, the high Ni content in NiTi alloys is still a concern for its long-term applications in the human body. The release of Ni ion into the human body might cause serious problems, as Ni is capable of eliciting toxic and allergic responses. In view of this, surface modification to reduce the surface content of Ni and to improve the corrosion resistance, both of which would reduce Ni release, is an important step in the development of NiTi implants. In the present study, NiTi was surface alloyed with Nb or Co by laser processing. The fine dendritic structure characteristic of laser processing has been described in terms of rapid solidification. The amount of surface elemental Ni was reduced to 10% and 35% for the Nb-alloyed and Co-alloyed layer, respectively. The corrosion resistance in Hanks' solution (a simulated body fluid) was increased as evidenced by a reduced passive current density and a higher pitting potential for both the Nb- and Co-alloyed specimens. The composition and hardness profiles along the depth of the modified layer were correlated with the distribution of the dendrites. The microhardness of the alloyed layers was around 700-800 Hv, which was about four times that of the untreated NiTi specimens.

  3. Method for creating high carbon content products from biomass oil

    DOEpatents

    Parker, Reginald; Seames, Wayne

    2012-12-18

    In a method for producing high carbon content products from biomass, a biomass oil is added to a cracking reactor vessel. The biomass oil is heated to a temperature ranging from about 100.degree. C. to about 800.degree. C. at a pressure ranging from about vacuum conditions to about 20,700 kPa for a time sufficient to crack the biomass oil. Tar is separated from the cracked biomass oil. The tar is heated to a temperature ranging from about 200.degree. C. to about 1500.degree. C. at a pressure ranging from about vacuum conditions to about 20,700 kPa for a time sufficient to reduce the tar to a high carbon content product containing at least about 50% carbon by weight.

  4. The underlying biological mechanisms of biocompatibility differences between bare and TiN-coated NiTi alloys.

    PubMed

    Lifeng, Zhao; Yan, Hong; Dayun, Yang; Xiaoying, Lü; Tingfei, Xi; Deyuan, Zhang; Ying, Hong; Jinfeng, Yuan

    2011-04-01

    TiN coating has been demonstrated to improve the biocompatibility of bare NiTi alloys; however, essential biocompatibility differences between NiTi alloys before and after TiN coating are not known so far. In this study, to explore the underlying biological mechanisms of biocompatibility differences between them, the changes of bare and TiN-coated NiTi alloys in surface chemical composition, morphology, hydrophilicity, Ni ions release, cytotoxicity, apoptosis, and gene expression profiles were compared using energy-dispersive spectroscopy, scanning electron microscopy, contact angle, surface energy, Ni ions release analysis, the methylthiazoltetrazolium (MTT) method, flow cytometry and microarray methods, respectively. Pathways binding to networks and real-time polymerase chain reaction (PCR) were employed to analyze and validate the microarray data, respectively. It was found that, compared with the bare NiTi alloys, TiN coating significantly decreased Ni ions content on the surfaces of the NiTi alloys and reduced the release of Ni ions from the alloys, attenuated the inhibition of Ni ions to the expression of genes associated with anti-inflammatory, and also suppressed the promotion of Ni ions to the expression of apoptosis-related genes. Moreover, TiN coating distinctly improved the hydrophilicity and uniformity of the surfaces of the NiTi alloys, and contributed to the expression of genes participating in cell adhesion and other physiological activities. These results indicate that the TiN-coated NiTi alloys will help overcome the shortcomings of NiTi alloys used in clinical application currently, and can be expected to be a replacement of biomaterials for a medical device field. PMID:21441653

  5. Carbon and Nitrogen Content of Natural Planktonic Bacteria †

    PubMed Central

    Nagata, Toshi

    1986-01-01

    A method of estimating carbon and nitrogen content per unit of natural bacterial cell volume was developed. This method is based on the difference in the retentiveness of bacteria between two kinds of glass fiber filter, GF/C and GF/F (Whatman, Inc., Clifton, N.J.). Biovolume and biomass (carbon and nitrogen content) of bacteria which passed through the GF/C but not the GF/F filter were estimated with an epifluorescence microscopy and a CHN analyzer, respectively. From seasonal determinations of natural planktonic bacteria in epilimnetic waters of a mesotrophic lake, the conversion factors of 106 fg of C/μm3 and 25 fg of N/μm3 were derived as average values. By using these values, the contribution of bacteria to the biomass of lake plankton is discussed. PMID:16347114

  6. Modeling, Simulation, Additive Manufacturing, and Experimental Evaluation of Solid and Porous NiTi

    NASA Astrophysics Data System (ADS)

    Taheri Andani, Mohsen

    In recent years, shape memory alloys (SMAs) have entered a wide range of engineering applications in fields such as aerospace and medical applications. Nickel-titanium (NiTi) is the most commonly used SMAs due to its excellent functional characteristics (shape memory effect and superelasticity behavior). These properties are based on a solid-solid phase transformation between martensite and austenite. Beside these two characteristics, low stiffness, biocompatibility and corrosion properties of NiTi make it an attractive candidate for biomedical applications (e.g., bone plates, bone screws, and vascular stents). It is well know that manufacturing and processing of NiTi is very challenging. The functional properties of NiTi are significantly affected by the impurity level and due to the high titanium content, NiTi are highly reactive. Therefore, high temperature processed parts through methods such as melting and casting which result in increased impurity levels have inadequate structural and functional properties. Furthermore, high ductility and elasticity of NiTi, adhesion, work hardening and spring back effects make machining quite challenging. These unfavorable effects for machining cause significant tool wear along with decreasing the quality of work piece. Recently, additive manufacturing (AM) has gained significant attention for manufacturing NiTi. Since AM can create a part directly from CAD data, it is predicted that AM can overcome most of the manufacturing difficulties. This technique provides the possibility of fabricating highly complex parts, which cannot be processed by any other methods. Curved holes, designed porosity, and lattice like structures are some examples of mentioned complex parts. This work investigates manufacturing superelastic NiTi by selective laser melting (SLM) technique (using PXM by Phenix/3D Systems). An extended experimental study is conducted on the effect of subsequent heat treatments with different aging conditions on phase

  7. Eutectic Syntheses of Graphitic Carbon with High Pyrazinic Nitrogen Content.

    PubMed

    Fechler, Nina; Zussblatt, Niels P; Rothe, Regina; Schlögl, Robert; Willinger, Marc-Georg; Chmelka, Bradley F; Antonietti, Markus

    2016-02-10

    Mixtures of phenols/ketones and urea show eutectic behavior upon gentle heating. These mixtures possess liquid-crystalline-like phases that can be processed. The architecture of phenol/ketone acts as structure-donating motif, while urea serves as melting-point reduction agent. Condensation at elevated temperatures results in nitrogen-containing carbons with remarkably high nitrogen content of mainly pyrazinic nature. PMID:26178584

  8. A Reassessment of Carbon Content in Tropical Trees

    PubMed Central

    Martin, Adam R.; Thomas, Sean C.

    2011-01-01

    Accurate knowledge of carbon (C) content in live wood is essential for quantifying tropical forest C stocks, yet generic assumptions (such as biomass consisting of 50% carbon on a weight/weight basis) remain widely used despite being supported by little chemical analysis. Empirical data from stem cores of 59 Panamanian rainforest tree species demonstrate that wood C content is highly variable among co-occurring species, with an average (47.4±2.51% S.D.) significantly lower than widely assumed values. Prior published values have neglected to account for volatile C content of tropical woods. By comparing freeze- and oven-dried wood samples, we show that volatile C is non-negligible, and excluding the volatile fraction underestimates wood C content by 2.48±1.28% (S.D.) on average. Wood C content varied substantially among species (from 41.9–51.6%), but was neither strongly phylogenetically conserved, nor correlated to ecological (i.e. wood density, maximum tree height) or demographic traits (i.e. relative growth rate, mortality rate). Overall, assuming generic C fractions in tropical wood overestimates forest C stocks by ∼3.3–5.3%, a non-trivial margin of error leading to overestimates of 4.1–6.8 Mg C ha−1 in a 50-ha forest dynamics plot on Barro Colorado Island, Panama. In addition to addressing other sources of error in tropical forest C accounting, such as uncertainties in allometric models and belowground biomass, compilation and use of species-specific C fractions for tropical tree species would substantially improve both local and global estimates of terrestrial C stocks and fluxes. PMID:21858157

  9. Size and Carbon Content of Sub-seafloor Microbial Cells

    NASA Astrophysics Data System (ADS)

    Braun, S.; Morono, Y.; Littmann, S.; Jørgensen, B. B.; Lomstein, B. A.

    2015-12-01

    Into the seafloor, a radical decline in nutrient and energy availability poses strong metabolic demands to any residing life. However, a sedimentary microbial ecosystem seems to maintain itself close to what we understand to be the energetic limit of life. Since a complex sediment matrix is interfering with the analysis of whole cells and sub-cellular compounds such as cell wall and membrane molecules, little is known about the physiological properties of cells in the deep biosphere. Here we focus on the size and carbon content of cells from a 90-m sediment drill core retrieved in October 2013 at Landsort Deep, Baltic Sea, in 437 meters water depth. To determine their shape and volume, cells were separated from the sediment matrix by multi-layer density centrifugation and visualized via fluorescence microscopy (FM), scanning electron microscopy (SEM), and stimulated emission depletion microscopy (STED). Total cell-carbon was calculated from amino acid-carbon, which was analyzed by high-performance liquid chromatography after cells had additionally been purified by fluorescence activated cell sorting (FACS). Cell-carbon turnover times were estimated using an amino acid racemization model that is based on the built-in molecular clock of aspartic acid, which due to racemization alternates between the D- and L-isomeric configurations over timescales of thousands of years at low in-situ temperatures (≈4˚C). We find that the majority of microbial cells in the sediment have coccoid or rod-shaped morphology, and that absolute values for cell volume are strongly dependent on the method used, spanning three orders of magnitude from approximately 0.001 to 1 µm3 for both coccoid and rod-shaped cells. From the surface to the deepest sample measured (≈60 mbsf), cell volume decreases by an order of magnitude, and carbon content is in the lower range (<20 fg C cell-1) of what has been reported in the literature as conversion factors. Cell-carbon is turned over approximately

  10. Modelling and mapping the topsoil organic carbon content for Tanzania

    NASA Astrophysics Data System (ADS)

    Kempen, Bas; Kaaya, Abel; Ngonyani Mhaiki, Consolatha; Kiluvia, Shani; Ruiperez-Gonzalez, Maria; Batjes, Niels; Dalsgaard, Soren

    2014-05-01

    Soil organic carbon (SOC), held in soil organic matter, is a key indicator of soil health and plays an important role in the global carbon cycle. The soil can act as a net source or sink of carbon depending on land use and management. Deforestation and forest degradation lead to the release of vast amounts of carbon from the soil in the form of greenhouse gasses, especially in tropical countries. Tanzania has a high deforestation rate: it is estimated that the country loses 1.1% of its total forested area annually. During 2010-2013 Tanzania has been a pilot country under the UN-REDD programme. This programme has supported Tanzania in its initial efforts towards reducing greenhouse gas emission from forest degradation and deforestation and towards preserving soil carbon stocks. Formulation and implementation of the national REDD strategy requires detailed information on the five carbon pools among these the SOC pool. The spatial distribution of SOC contents and stocks was not available for Tanzania. The initial aim of this research, was therefore to develop high-resolution maps of the SOC content for the country. The mapping exercise was carried out in a collaborative effort with four Tanzanian institutes and data from the Africa Soil Information Service initiative (AfSIS). The mapping exercise was provided with over 3200 field observations on SOC from four sources; this is the most comprehensive soil dataset collected in Tanzania so far. The main source of soil samples was the National Forest Monitoring and Assessment (NAFORMA). The carbon maps were generated by means of digital soil mapping using regression-kriging. Maps at 250 m spatial resolution were developed for four depth layers: 0-10 cm, 10-20 cm, 20-30 cm, and 0-30 cm. A total of 37 environmental GIS data layers were prepared for use as covariates in the regression model. These included vegetation indices, terrain parameters, surface temperature, spectral reflectances, a land cover map and a small

  11. Measurement of carbon storage in landfills from the biogenic carbon content of excavated waste samples.

    PubMed

    De la Cruz, Florentino B; Chanton, Jeffrey P; Barlaz, Morton A

    2013-10-01

    Landfills are an anaerobic ecosystem and represent the major disposal alternative for municipal solid waste (MSW) in the U.S. While some fraction of the biogenic carbon, primarily cellulose (Cel) and hemicellulose (H), is converted to carbon dioxide and methane, lignin (L) is essentially recalcitrant. The biogenic carbon that is not mineralized is stored within the landfill. This carbon storage represents a significant component of a landfill carbon balance. The fraction of biogenic carbon that is not reactive in the landfill environment and therefore stored was derived for samples of excavated waste by measurement of the total organic carbon, its biogenic fraction, and the remaining methane potential. The average biogenic carbon content of the excavated samples was 64.6±18.0% (average±standard deviation), while the average carbon storage factor was 0.09±0.06g biogenic-C stored per g dry sample or 0.66±0.16g biogenic-C stored per g biogenic C.

  12. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    SciTech Connect

    Wang, Hao; Wang, Yun; Dai, Xiao; Zou, Guifu E-mail: zouguifu@suda.edu.cn; Gao, Peng; Zhang, Ke-Qin E-mail: zouguifu@suda.edu.cn; Du, Dezhuang; Guo, Jun

    2015-08-01

    In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

  13. Correlation between calcium carbonate content and emission characteristics of incense.

    PubMed

    Yang, Chi-Ru; Lin, Ta-Chang; Chang, Feng-Hsiang

    2006-12-01

    In Taiwan and China, calcium carbonate is commonly added as a filler during incense production to lower the cost. This study has found an unexpected benefit for this practice: it reduces particulate emission. Nine types of the popular incense on the local market were chosen for this study. The calcium content in raw material incense was analyzed by inductively coupled plasma atomic emission spectrometry, followed by X-ray diffraction (XRD) spectroscopy. The correlation between the calcium content and emission characteristics of incense was investigated. The calcium content varied from 1.8 to 60 mg/g (incense burned) among those nine different types of incense. Very little calcium (< 1%) was found in natural wood or plants, which is mainly the raw material of incense. Instead, most calcium was artificially added in the form of CaCO3 during manufacturing. The combustion characteristics, including burning rate, emission factors of particulate, ash, and solid-phase polycyclic aromatic hydrocarbons (S-PAHs), varied significantly among the nine types of incense. Incense containing 2% calcium would emit 30% less S-PAHs, compared with those with little (< 0.2%) calcium. More importantly, increasing the calcium content from 0.5 to 5% by adding CaCO3 reduced the particulate emission from incense by approximately 50%.

  14. Surface characteristics, corrosion and bioactivity of chemically treated biomedical grade NiTi alloy.

    PubMed

    Chembath, Manju; Balaraju, J N; Sujata, M

    2015-11-01

    The surface of NiTi alloy was chemically modified using acidified ferric chloride solution and the characteristics of the alloy surface were studied from the view point of application as a bioimplant. Chemically treated NiTi was also subjected to post treatments by annealing at 400°C and passivation in nitric acid. The surface of NiTi alloy after chemical treatment developed a nanogrid structure with a combination of one dimensional channel and two dimensional network-like patterns. From SEM studies, it was found that the undulations formed after chemical treatment remained unaffected after annealing, while after passivation process the undulated surface was filled with oxides of titanium. XPS analysis revealed that the surface of passivated sample was enriched with oxides of titanium, predominantly TiO2. The influence of post treatment on the corrosion resistance of chemically treated NiTi alloy was monitored using Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) in Phosphate Buffered Saline (PBS) solution. In the chemically treated condition, NiTi alloy exhibited poor corrosion resistance due to the instability of the surface. On the other hand, the breakdown potential (0.8V) obtained was highest for the passivated samples compared to other surface treated samples. During anodic polarization, chemically treated samples displayed dissolution phenomenon which was predominantly activation controlled. But after annealing and passivation processes, the behavior of anodic polarization was typical of a diffusion controlled process which confirmed the enhanced passivity of the post treated surfaces. The total resistance, including the porous and barrier layer, was in the range of mega ohms for passivated surfaces, which could be attributed to the decrease in surface nickel content and formation of compact titanium oxide. The passivated sample displayed good bioactivity in terms of hydroxyapatite growth, noticed after 14days immersion in

  15. The Stable and Radio- Carbon Isotopic Content of Labile and Refractory Carbon in Atmospheric Particulate Matter

    NASA Astrophysics Data System (ADS)

    McNichol, A. P.; Rosenheim, B. E.; Gerlach, D. S.; Hayes, J. M.

    2006-12-01

    Studies of the isotopic content of atmospheric particulate matter are hampered by difficulties in chemically defining the pools of carbon and analytically isolating the different pools. We are conducting studies on reference materials and atmospheric aerosol samples to develop a method to measure stable and radio- carbon isotopes on the labile and refractory carbon. We are using a flow-through combustion system that allows us to combust, collect and measure the isotopic content of the gases produced at all stages of heating/oxidizing. We compare our results to those measured using a chemothermal oxidation method (CTO) (Gustafsson et al., 2001). In this method, refractory carbon is defined as the material remaining after pre- combusting a sample at 375°C in the presence of oxygen for 24 hours. The reference materials are diesel soot, apple leaves and a hybrid of the two (DiesApple), all from NIST. These provide carbon with two well-defined fractions -- the soot provides refractory carbon that is radiocarbon dead and the apple leaves provide organic carbon that is radiocarbon modern. Radiocarbon results from DiesApple indicate that the "refractory" carbon defined by the CTO method is actually a mixture of old and modern carbon that contains over 25% modern carbon. This suggests that charred material formed from the apples leaves during the pre-combustion step is contributing to the fraction we identify as refractory carbon. We are studying this by analyzing the individual materials and the mixture using our flow-through system. First results with this system indicate that the refractory fraction trapped from the DiesApple contains much less modern carbon than the CTO method, less than 7%. We will present detailed concentration and isotopic results of the generation of carbon dioxide during programmed combustion of each of the reference materials. We studied the radiocarbon content of both the total carbon (TC) and refractory carbon in the fine particulate matter (PM

  16. Elevated carbon dioxide and ozone alter productivity and ecosystem carbon content in northern temperate forests.

    PubMed

    Talhelm, Alan F; Pregitzer, Kurt S; Kubiske, Mark E; Zak, Donald R; Campany, Courtney E; Burton, Andrew J; Dickson, Richard E; Hendrey, George R; Isebrands, J G; Lewin, Keith F; Nagy, John; Karnosky, David F

    2014-08-01

    Three young northern temperate forest communities in the north-central United States were exposed to factorial combinations of elevated carbon dioxide (CO2 ) and tropospheric ozone (O3 ) for 11 years. Here, we report results from an extensive sampling of plant biomass and soil conducted at the conclusion of the experiment that enabled us to estimate ecosystem carbon (C) content and cumulative net primary productivity (NPP). Elevated CO2 enhanced ecosystem C content by 11%, whereas elevated O3 decreased ecosystem C content by 9%. There was little variation in treatment effects on C content across communities and no meaningful interactions between CO2 and O3 . Treatment effects on ecosystem C content resulted primarily from changes in the near-surface mineral soil and tree C, particularly differences in woody tissues. Excluding the mineral soil, cumulative NPP was a strong predictor of ecosystem C content (r(2) = 0.96). Elevated CO2 enhanced cumulative NPP by 39%, a consequence of a 28% increase in canopy nitrogen (N) content (g N m(-2) ) and a 28% increase in N productivity (NPP/canopy N). In contrast, elevated O3 lowered NPP by 10% because of a 21% decrease in canopy N, but did not impact N productivity. Consequently, as the marginal impact of canopy N on NPP (∆NPP/∆N) decreased through time with further canopy development, the O3 effect on NPP dissipated. Within the mineral soil, there was less C in the top 0.1 m of soil under elevated O3 and less soil C from 0.1 to 0.2 m in depth under elevated CO2 . Overall, these results suggest that elevated CO2 may create a sustained increase in NPP, whereas the long-term effect of elevated O3 on NPP will be smaller than expected. However, changes in soil C are not well-understood and limit our ability to predict changes in ecosystem C content.

  17. Elevated carbon dioxide and ozone alter productivity and ecosystem carbon content in northern temperate forests.

    PubMed

    Talhelm, Alan F; Pregitzer, Kurt S; Kubiske, Mark E; Zak, Donald R; Campany, Courtney E; Burton, Andrew J; Dickson, Richard E; Hendrey, George R; Isebrands, J G; Lewin, Keith F; Nagy, John; Karnosky, David F

    2014-08-01

    Three young northern temperate forest communities in the north-central United States were exposed to factorial combinations of elevated carbon dioxide (CO2 ) and tropospheric ozone (O3 ) for 11 years. Here, we report results from an extensive sampling of plant biomass and soil conducted at the conclusion of the experiment that enabled us to estimate ecosystem carbon (C) content and cumulative net primary productivity (NPP). Elevated CO2 enhanced ecosystem C content by 11%, whereas elevated O3 decreased ecosystem C content by 9%. There was little variation in treatment effects on C content across communities and no meaningful interactions between CO2 and O3 . Treatment effects on ecosystem C content resulted primarily from changes in the near-surface mineral soil and tree C, particularly differences in woody tissues. Excluding the mineral soil, cumulative NPP was a strong predictor of ecosystem C content (r(2) = 0.96). Elevated CO2 enhanced cumulative NPP by 39%, a consequence of a 28% increase in canopy nitrogen (N) content (g N m(-2) ) and a 28% increase in N productivity (NPP/canopy N). In contrast, elevated O3 lowered NPP by 10% because of a 21% decrease in canopy N, but did not impact N productivity. Consequently, as the marginal impact of canopy N on NPP (∆NPP/∆N) decreased through time with further canopy development, the O3 effect on NPP dissipated. Within the mineral soil, there was less C in the top 0.1 m of soil under elevated O3 and less soil C from 0.1 to 0.2 m in depth under elevated CO2 . Overall, these results suggest that elevated CO2 may create a sustained increase in NPP, whereas the long-term effect of elevated O3 on NPP will be smaller than expected. However, changes in soil C are not well-understood and limit our ability to predict changes in ecosystem C content. PMID:24604779

  18. Water, hydrogen, deuterium, carbon, carbon-13, and oxygen-18 content of selected lunar material

    USGS Publications Warehouse

    Friedman, I.; O'Neil, J.R.; Adami, L.H.; Gleason, J.D.; Hardcastle, K.

    1970-01-01

    The water content of the breccia is 150 to 455 ppm, with a ??D from -580 to -870 per mil. Hydrogen gas content is 40 to 53 ppm with a ??D of -830 to -970 per mil. The CO2 is 290 to 418 ppm with S 13C = + 2.3 to + 5.1 per mil and ??18O = 14.2 to 19.1 per mil. Non-CO2 carbon is 22 to 100 ppm, ??18C = -6.4 to -23.2 per mil. Lunar dust is 810 ppm H2O (D = 80 ppm) and 188 ppm total carbon (??13C = -17.6 per mil). The 18O analyses of whole rocks range from 5.8 to 6.2 per mil. The temperature of crystallization of type B rocks is 1100?? to 1300??C, based on the oxygen isotope fractionation between coexisting plagioclase and ilmenite.

  19. NiTi superelasticity via atomistic simulations

    NASA Astrophysics Data System (ADS)

    Chowdhury, Piyas; Ren, Guowu; Sehitoglu, Huseyin

    2015-12-01

    The NiTi shape memory alloys (SMAs) are promising candidates for the next-generation multifunctional materials. These materials are superelastic i.e. they can fully recover their original shape even after fairly large inelastic deformations once the mechanical forces are removed. The superelasticity reportedly stems from atomic scale crystal transformations. However, very few computer simulations have emerged, elucidating the transformation mechanisms at the discrete lattice level, which underlie the extraordinary strain recoverability. Here, we conduct breakthrough molecular dynamics modelling on the superelastic behaviour of the NiTi single crystals, and unravel the atomistic genesis thereof. The deformation recovery is clearly traced to the reversible transformation between austenite and martensite crystals through simulations. We examine the mechanistic origin of the tension-compression asymmetries and the effects of pressure/temperature/strain rate variation isolatedly. Hence, this work essentially brings a new dimension to probing the NiTi performance based on the mesoscale physics under more complicated thermo-mechanical loading scenarios.

  20. Determining water content in activated carbon for double-layer capacitor electrodes

    NASA Astrophysics Data System (ADS)

    Egashira, Minato; Izumi, Takuma; Yoshimoto, Nobuko; Morita, Masayuki

    2016-09-01

    Karl-Fisher titration is used to estimate water contents in activated carbon and the distribution of impurity-level water in an activated carbon-solvent system. Normalization of the water content of activated carbon is attempted using vacuum drying after immersion in water was controlled. Although vacuum drying at 473 K and 24 h can remove large amounts of water, a substantial amount of water remains in the activated carbon. The water release to propylene carbonate is less than that to acetonitrile. The degradation of capacitor cell capacitance for activated carbon with some amount of water differs according to the electrolyte solvent type: acetonitrile promotes greater degradation than propylene carbonate does.

  1. Effect of carbon content on friction and wear of cast irons

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1977-01-01

    Friction and wear experiments were conducted with cast irons and wrought steels containing various amounts of carbon in the alloy structure in contact with 52100 steel. Gray cast irons were found to exhibit lower friction and wear characteristics than white cast irons. Further, gray cast iron wear was more sensitive to carbon content than was white. Wear with gray cast iron was linearly related to load, and friction was found to be sensitive to relative humidity and carbon content. The form, in which the carbon is present in the alloy, is more important, as the carbon content and no strong relationship seems to exist between hardness of these ferrous alloys and wear.

  2. The transformation behaviour of bulk nanostructured NiTi alloys

    NASA Astrophysics Data System (ADS)

    Neves, F.; Braz Fernandes, F. M.; Martins, I.; Correia, J. B.; Oliveira, M.; Gaffet, E.; Wang, T.-Y.; Lattemann, M.; Suffner, J.; Hahn, H.

    2009-11-01

    The phase transformation behaviour of bulk nanostructured NiTi shape memory alloys, produced by an innovative approach called MARES (mechanically activated reactive extrusion synthesis), was investigated using in situ x-ray diffraction and differential scanning calorimetry measurements. For the experimental conditions used, a suitable adjustment of the NiTi matrix composition was achieved after ageing at 500 °C for 7 h. The aged materials showed a homogeneous dispersion of Ni4Ti3 precipitates embedded in a B2-NiTi matrix. Under this condition the B2-NiTi matrix has undergone a \\mathrm {B2 \\leftrightarrow R \\leftrightarrow B19'} two-stage phase transformation. This was attributed to the complex microstructural evolution during MARES processing, i.e. formation of large-scale and small-scale heterogeneities. Transmission electron microscopy investigations of the solution-treated materials showed the existence of equiaxed nanocrystals in the nanocrystalline NiTi matrix.

  3. Advanced Chinese NiTi alloy wire and clinical observations.

    PubMed

    Chen, R; Zhi, Y F; Arvystas, M G

    1992-01-01

    Chinese NiTi wire was studied on the bench with six other nickel-titanium-alloy wires. Bending and torsional tests were conducted and temperatures of phase transformation compared. The Chinese NiTi wire was found to have a low stiffness, high springback and constant bending and torsional moments on unloading, in a very large deformation region. It can produce a gentle, nearly constant force. These factors make it desirable for clinical application. Included in this paper are clinical observations of case selected from over 100 patients in current treatment with Chinese NiTi wires. Chinese NiTi wire reduced the leveling and alignment phase of treatment without discomfort to the patient. Chinese NiTi wire can be used in both children and adults. PMID:1445516

  4. Corrosion of NiTi Wires with Cracked Oxide Layer

    NASA Astrophysics Data System (ADS)

    Racek, Jan; Šittner, Petr; Heller, Luděk; Pilch, Jan; Petrenec, Martin; Sedlák, Petr

    2014-07-01

    Corrosion behavior of superelastic NiTi shape memory alloy wires with cracked TiO2 surface oxide layers was investigated by electrochemical corrosion tests (Electrochemical Impedance Spectroscopy, Open Circuit Potential, and Potentiodynamic Polarization) on wires bent into U-shapes of various bending radii. Cracks within the oxide on the surface of the bent wires were observed by FIB-SEM and TEM methods. The density and width of the surface oxide cracks dramatically increase with decreasing bending radius. The results of electrochemical experiments consistently show that corrosion properties of NiTi wires with cracked oxide layers (static load keeps the cracks opened) are inferior compared to the corrosion properties of the straight NiTi wires covered by virgin uncracked oxides. Out of the three methods employed, the Electrochemical Impedance Spectroscopy seems to be the most appropriate test for the electrochemical characterization of the cracked oxide layers, since the impedance curves (Nyquist plot) of differently bent NiTi wires can be associated with increasing state of the surface cracking and since the NiTi wires are exposed to similar conditions as the surfaces of NiTi implants in human body. On the other hand, the potentiodynamic polarization test accelerates the corrosion processes and provides clear evidence that the corrosion resistance of bent superelastic NiTi wires degrades with oxide cracking.

  5. Inferring Absorbing Organic Carbon Content from AERONET Data

    NASA Technical Reports Server (NTRS)

    Arola, A.; Schuster, G.; Myhre, G.; Kazadzis, S.; Dey, S.; Tripathi, S. N.

    2011-01-01

    Black carbon, light-absorbing organic carbon (often called brown carbon) and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated globally the amount of light absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon) levels in biomass burning regions of South-America and Africa are relatively high (about 15-20 magnesium per square meters during biomass burning season), while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30-35 magnesium per square meters during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while opposite is true in urban areas in India and China.

  6. Nondestructive evaluation of Ni-Ti shape memory alloy

    SciTech Connect

    Meir, S.; Gordon, S.; Karsh, M.; Ayers, R.; Olson, D. L.; Wiezman, A.

    2011-06-23

    The nondestructive evaluation of nickel titanium (Ni-Ti) alloys for applications such as heat treatment for biomaterials applications (dental) and welding was investigated. Ni-Ti alloys and its ternary alloys are valued for mechanical properties in addition to the shape memory effect. Two analytical approaches were perused in this work. Assessment of the microstructure of the alloy that determines the martensitic start temperature (Ms) of Ni-Ti alloy as a function of heat treatment, and secondly, an attempt to evaluate a Friction Stir Welding, which involves thermo-mechanical processing of the alloy.

  7. Gas-phase photoacoustic determination of the total carbon content of aerosol deposits.

    PubMed

    Pleil, J D; Russwurm, G M; McClenny, W A

    1982-01-01

    A prototype system was constructed to determine the total carbon content of ambient aerosols trapped on quartz fiber filters. The measurement technique is based on carbon combustion to CO(2), cryogenic precon-centration, and subsequent photoacoustic monitoring of produced CO(2). A common sample set was independently analyzed by two established combustion method instruments and the photoacoustic system. Statistical comparison of data showed good agreement with accepted carbon values indicating feasibility for photoacoustic application to routine carbon analysis. PMID:20372416

  8. Atomistic Modeling of Pd Site Preference in NiTi

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Mosca, Hugo O.

    2004-01-01

    An analysis of the site subsitution behavior of Pd in NiTi was performed using the BFS method for alloys. Through a combination of Monte Carlo simulations and detailed atom-by-atom energetic analyses of various computational cells, representing compositions of NiTi with up to 10 at% Pd, a detailed understanding of site occupancy of Pd in NiTi was revealed. Pd subsituted at the expense of Ni in a NiTi alloy will prefer the Ni-sites. Pd subsituted at the expense of Ti shows a very weak preference for Ti-sites that diminishes as the amount of Pd in the alloy increases and as the temperature increases.

  9. Shape memory effect of laser welded NiTi plates

    NASA Astrophysics Data System (ADS)

    Oliveira, J. P.; Fernandes, F. M. Braz; Schell, N.; Miranda, R. M.

    2015-07-01

    Laser welding is a suitable joining technique for shape memory alloys (SMAs). This paper reports the existence of shape memory effect (SME) on laser welded NiTi joints, subjected to bending tests, and correlates this effect with the microstructural analysis performed with X-ray diffraction (XRD). All welded samples were able to recover their initial shape after bending to 180°, which is a remarkable result for industrial applications of NiTi involving laser welding.

  10. Phase composition in NiTi near-surface layers after electron beam treatment and its variation depending on beam energy density

    SciTech Connect

    Ostapenko, Marina G.; Meisner, Ludmila L.; Lotkov, Aleksandr I. E-mail: egu@ispms.tsc.ru; Gudimova, Ekaterina Y. E-mail: egu@ispms.tsc.ru

    2014-11-14

    In the work, we study the mechanisms of structural phase state formation in NiTi surface layers after low-energy pulsed electron beam irradiation depending on the electron beam energy density. It is revealed that after electron beam treatment of the NiTi specimens at energy densities E{sub 1} = 15 J/cm{sup 2}, E{sub 2} = 20 J/cm{sup 2}, and E{sub 3} = 30 J/cm{sup 2}, a series of effects is observed: the absence of the Ti2Ni phase and the presence of new peaks correspond to the B19′ martensite phase with monoclinic structure. Estimation of the relative volume content of the B2 and B19′ phases from the total intensity of their peaks shows that the percentage of the martensite phase increases from ∼5 vol.% in the NiTi specimen irradiated at E{sub 1} = 15 J/cm{sup 2} to ∼80 vol.% in the NiTi specimen irradiated at E{sub 3} = 30 J/cm{sup 2}. It is found that in the NiTi specimens irradiated at E ≤ 20 J/cm{sup 2}, the layer that contains a martensite phase resides not on the surface but at some depth from it.

  11. Evaluation of passive oxide layer formation-biocompatibility relationship in NiTi shape memory alloys: geometry and body location dependency.

    PubMed

    Toker, S M; Canadinc, D; Maier, H J; Birer, O

    2014-03-01

    A systematic set of ex-situ experiments were carried out on Nickel-Titanium (NiTi) shape memory alloy (SMA) in order to identify the dependence of its biocompatibility on sample geometry and body location. NiTi samples with three different geometries were immersed into three different fluids simulating different body parts. The changes observed in alloy surface and chemical content of fluids upon immersion experiments designed for four different time periods were analyzed in terms of ion release, oxide layer formation, and chemical composition of the surface layer. The results indicate that both sample geometry and immersion fluid significantly affect the alloy biocompatibility, as evidenced by the passive oxide layer formation on the alloy surface and ion release from the samples. Upon a 30 day immersion period, all three types of NiTi samples exhibited lower ion release than the critical value for clinic applications. However; a significant amount of ion release was detected in the case of gastric fluid, warranting a thorough investigation prior to utility of NiTi in gastrointestinal treatments involving long-time contact with tissue. Furthermore, certain geometries appear to be safer than the others for each fluid, providing a new set of guidelines to follow while designing implants making use of NiTi SMAs to be employed in treatments targeting specific body parts.

  12. Porous NiTi for bone implants: A review

    PubMed Central

    Bansiddhi, A.; Sargeant, T.D.; Stupp, S.I.; Dunand, D.C.

    2011-01-01

    NiTi foams are unique among biocompatible porous metals because of their high recovery strain (due to the shape-memory or superelastic effects) and their low stiffness facilitating integration with bone structures. To optimize NiTi foams for bone implant applications, two key areas are under active study: synthesis of foams with optimal architectures, microstructure and mechanical properties; and tailoring of biological interactions through modifications of pore surfaces. This article reviews recent research on NiTi foams for bone replacement, focusing on three specific topics: (i) surface modifications designed to create bio-inert porous NiTi surfaces with low Ni release and corrosion, as well as bioactive surfaces to enhance and accelerate biological activity; (ii) In vitro and in vivo biocompatibility studies to confirm the long-term safety of porous NiTi implants; and (iii) biological evaluations for specific applications, such as in intervertebral fusion devices and bone tissue scaffolds. Possible future directions for bio-performance and processing studies are discussed that could lead to optimized porous NiTi implants. PMID:18348912

  13. Porous NiTi for bone implants: a review.

    PubMed

    Bansiddhi, A; Sargeant, T D; Stupp, S I; Dunand, D C

    2008-07-01

    NiTi foams are unique among biocompatible porous metals because of their high recovery strain (due to the shape-memory or superelastic effects) and their low stiffness facilitating integration with bone structures. To optimize NiTi foams for bone implant applications, two key areas are under active study: synthesis of foams with optimal architectures, microstructure and mechanical properties; and tailoring of biological interactions through modifications of pore surfaces. This article reviews recent research on NiTi foams for bone replacement, focusing on three specific topics: (i) surface modifications designed to create bio-inert porous NiTi surfaces with low Ni release and corrosion, as well as bioactive surfaces to enhance and accelerate biological activity; (ii) in vitro and in vivo biocompatibility studies to confirm the long-term safety of porous NiTi implants; and (iii) biological evaluations for specific applications, such as in intervertebral fusion devices and bone tissue scaffolds. Possible future directions for bio-performance and processing studies are discussed that could lead to optimized porous NiTi implants.

  14. Chinese NiTi wire--a new orthodontic alloy.

    PubMed

    Burstone, C J; Qin, B; Morton, J Y

    1985-06-01

    Chinese NiTi wire was studied by means of a bending test to determine wire stiffness, springback, and maximum bending moments. Chinese NiTi wire has an unusual deactivation curve (unlike steel and nitinol wires) in which relatively constant forces are produced over a long range of action. The characteristic flexural stiffness of NiTi wire is determined by the amount of activation. At large activations NiTi wires has a stiffness of only 7% that of a comparable stainless steel wire, and at small activations 28% of steel wire. For the same activation at large deflections, the forces produced are 36% that of a comparable nitinol wire. Chinese NiTi wire demonstrates phenomenal springback. It can be deflected 1.6 times as far as nitinol wire or 4.4 times as far as stainless steel wire without appreciable permanent deformation. NiTi wire is highly useful in clinical situations that require a low-stiffness wire with an extremely large springback. PMID:3890554

  15. A New Route for Unburned Carbon Concentration Measurements Eliminating Mineral Content and Coal Rank Effects

    PubMed Central

    Liu, Dong; Duan, Yuan-Yuan; Yang, Zhen; Yu, Hai-Tong

    2014-01-01

    500 million tons of coal fly ash are produced worldwide every year with only 16% of the total amount utilized. Therefore, potential applications using fly ash have both environmental and industrial interests. Unburned carbon concentration measurements are fundamental to effective fly ash applications. Current on-line measurement accuracies are strongly affected by the mineral content and coal rank. This paper describes a char/ash particle cluster spectral emittance method for unburned carbon concentration measurements. The char/ash particle cluster spectral emittance is predicted theoretically here for various unburned carbon concentrations to show that the measurements are sensitive to unburned carbon concentration but insensitive to the mineral content and coal rank at short wavelengths. The results show that the char/ash particle cluster spectral emittance method is a novel and promising route for unburned carbon concentration on-line measurements without being influenced by mineral content or coal rank effects. PMID:24691496

  16. Research on carbon content in fly ash from circulating fluidized bed boilers

    SciTech Connect

    Xianbin Xiao; Hairui Yang; Hai Zhang; Junfu Lu; Guangxi Yue

    2005-08-01

    The carbon content in the fly ash from most Chinese circulating fluidized bed (CFB) boilers is much higher than expected, which directly influences the combustion efficiency. In the present paper, carbon burnout was investigated in both field tests and laboratory experiments. The effect of coal property, operation condition, gas-solid mixing, char deactivation, residence time, and cyclone performance are analyzed seriatim based on a large amount of experimental results. A coal index is proposed to describe the coal rank, having a strong effect on the char burnout. Bad gas-solid mixing in the furnace is another important reason of the higher carbon content in the fly ash. Some chars in the fly ash are deactivated during combustion of large coal particles and have very low carbon reactivity. Several suggestions are made about design, operation, and modification to reduce the carbon content in the fly ash. 14 refs., 14 figs., 1 tab.

  17. Investigating the Role of Carbonate Ion Concentration on the Magnesium Content of Amorphous Calcium Carbonate

    NASA Astrophysics Data System (ADS)

    Blue, C.; Dove, P. M.; Han, N.

    2011-12-01

    collection. The final ACC samples were characterized using a combination of SEM, Raman Spectroscopy, and ICP-OES. Preliminary results indicate that the Mg content of ACC increases with the carbonate ion concentration of the input solution. This shift in composition corresponds with measurements of a smaller average particle size. Future work will determine if the ACC that forms at these different carbonate concentrations subsequently influences the composition and structure of the final crystalline products. Findings from this work may lead to better predictions of how biological calcification processes will respond to the shifts in carbonate chemistry that accompany ocean acidification.

  18. Determination of carbon content in bainitic ferrite and carbon distribution in austenite by using CBKLDP

    SciTech Connect

    Zhang, M.X.; Kelly, P.M.

    1998-03-01

    Convergent beam Kikuchi line diffraction patterns taken with a 10nm-diameter electron beam have been used to determine the lattice parameter and hence the carbon concentration in both ferrite and austenite. The experimental results show that bainitic ferrite is supersaturated in carbon and that, during ageing of austenite prior to the precipitation of cementite, the original carbon distribution across a grain becomes very nonuniform with distinct regions of both carbon enrichment and carbon depletion.

  19. Soil total carbon content, aggregation, bulk density, and penetration resistance of croplands and nearby grasslands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Converting native grassland (NGL) to cropland (CL) decreases soil organic matter contents (components of soil total carbon contents, STCCs), which often leads to soil degradation. Reestablishing grass on CL generally increases soil organic matter, which improves soil conditions. This study was condu...

  20. Carbon content of austenite in austempered ductile iron

    SciTech Connect

    Chang, L.C.

    1998-06-05

    The development of austempered ductile iron (ADI) is a major achievement in cast iron technology. The austempering heat treatment enables the ductile cast iron containing mainly strong bainitic ferrite and ductile carbon-enriched austenite, with some martensite transforms from austenite during cooling down to room temperature. A key factor controlling the stability of the retained austenite can be evaluated soundly using the thermodynamics principles. It is the purpose here to demonstrate that the data of ADI from numerous sources have a similar trend.

  1. Structural transformations in NiTi shape memory alloy nanowires

    NASA Astrophysics Data System (ADS)

    Mirzaeifar, Reza; Gall, Ken; Zhu, Ting; Yavari, Arash; DesRoches, Reginald

    2014-05-01

    Martensitic phase transformation in bulk Nickle-Titanium (NiTi)—the most widely used shape memory alloy—has been extensively studied in the past. However, the structures and properties of nanostructured NiTi remain poorly understood. Here, we perform molecular dynamics simulations to study structural transformations in NiTi nanowires. We find that the tendency to reduce the surface energy in NiTi nanowires can lead to a new phase transformation mechanism from the austenitic B2 to the martensitic B19 phase. We further show that the NiTi nanowires exhibit the pseudoelastic effects during thermo-mechanical cycling of loading and unloading via the B2 and B19 transformations. Our simulations also reveal the unique formation of compound twins, which are expected to dominate the patterning of the nanostructured NiTi alloys at high loads. This work provides the novel mechanistic insights into the martensitic phase transformations in nanostructured shape memory alloy systems.

  2. Contemporary carbon content of bis (2-ethylhexyl) phthalate in butter.

    PubMed

    Tong, T; Ondov, J M; Buchholz, B A; VanDerveer, M C

    2016-01-01

    The fraction of naturally produced bis (2-ethylhexyl) phthalate (DEHP), a ubiquitous plasticizer known to contaminate packaged foods, was determined for each of five 1.10 kg samples of unsalted market butter by accelerator mass spectrometry (AMS). After extraction and concentration enrichment with liquid-liquid extraction, flash column chromatography, and preparative-scale high performance liquid chromatography, each sample provided ≈ 250 μg extracts of DEHP with carbon purity ranging from 92.5 ± 1.2% (n = 3, 1σ) to 97.1 ± 0.8% (n = 3, 1σ) as measured with gas chromatography mass spectrometry (GC-MS). After corrections for method blank DEHP, co-eluting compounds, and unidentified carbon, the mean fraction of naturally produced DEHP in butter was determined to be 0.16 ± 0.12 (n = 5, 1σ). To our knowledge, this is the first report of the contemporary fraction of DEHP isolated from market butter in the U.S.

  3. Estimation of black carbon content for biomass burning aerosols from multi-channel Raman lidar data

    NASA Astrophysics Data System (ADS)

    Talianu, Camelia; Marmureanu, Luminita; Nicolae, Doina

    2015-04-01

    Biomass burning due to natural processes (forest fires) or anthropical activities (agriculture, thermal power stations, domestic heating) is an important source of aerosols with a high content of carbon components (black carbon and organic carbon). Multi-channel Raman lidars provide information on the spectral dependence of the backscatter and extinction coefficients, embedding information on the black carbon content. Aerosols with a high content of black carbon have large extinction coefficients and small backscatter coefficients (strong absorption), while aerosols with high content of organic carbon have large backscatter coefficients (weak absorption). This paper presents a method based on radiative calculations to estimate the black carbon content of biomass burning aerosols from 3b+2a+1d lidar signals. Data is collected at Magurele, Romania, at the cross-road of air masses coming from Ukraine, Russia and Greece, where burning events are frequent during both cold and hot seasons. Aerosols are transported in the free troposphere, generally in the 2-4 km altitude range, and reaches the lidar location after 2-3 days. Optical data are collected between 2011-2012 by a multi-channel Raman lidar and follows the quality assurance program of EARLINET. Radiative calculations are made with libRadTran, an open source radiative model developed by ESA. Validation of the retrievals is made by comparison to a co-located C-ToF Aerosol Mass Spectrometer. Keywords: Lidar, aerosols, biomass burning, radiative model, black carbon Acknowledgment: This work has been supported by grants of the Romanian National Authority for Scientific Research, Programme for Research- Space Technology and Advanced Research - STAR, project no. 39/2012 - SIAFIM, and by Romanian Partnerships in priority areas PNII implemented with MEN-UEFISCDI support, project no. 309/2014 - MOBBE

  4. The effect of heating rate on the surface chemistry of NiTi.

    PubMed

    Undisz, Andreas; Hanke, Robert; Freiberg, Katharina E; Hoffmann, Volker; Rettenmayr, Markus

    2014-11-01

    The impact of the heating rate on the Ni content at the surface of the oxide layer of biomedical NiTi is explored. Heat treatment emulating common shape-setting procedures was performed by means of conventional and inductive heating for similar annealing time and temperature, applying various heating rates from ~0.25 K s(-1) to 250 K s(-1). A glow discharge optical emission spectroscopy method was established and employed to evaluate concentration profiles of Ni, Ti and O in the near-surface region at high resolution. The Ni content at the surface of the differently treated samples varies significantly, with maximum surface Ni concentrations of ~20 at.% at the lowest and ~1.5 at.% at the highest heating rate, i.e. the total amount of Ni contained in the surface region of the oxide layer decreases by >15 times. Consequently, the heating rate is a determinant for the biomedical characteristics of NiTi, especially since Ni available at the surface of the oxide layer may affect the hemocompatibility and be released promptly after surgical application of a respective implant. Furthermore, apparently contradictory results presented in the literature reporting surface Ni concentrations of ~3 at.% to >20 at.% after heat treatment are consistently explained considering the ascertained effect of the heating rate.

  5. Oxide Scales Formed on NiTi and NiPtTi Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Garg, Anita; Rogers, Richard B.; Noebe, Ronald D.

    2011-01-01

    Ni-49Ti and Ni-30Pt-50Ti (at.%) shape memory alloys were oxidized isothermally in air over the temperature range of 500 to 900 C. The microstructure, composition, and phase content of the scales were studied by SEM, EDS, XRD, and metallography. Extensive plan view SEM/EDS identified various features of intact or spalled scale surfaces. The outer surface of the scale was a relatively pure TiO2 rutile structure, typified by a distinct highly striated and faceted crystal morphology. Crystal size increased significantly with temperature. Spalled regions exhibited some porosity and less distinct features. More detailed information was obtained by correlation of SEM/EDS studies of 700 C/100 hr cross-sections with XRD analyses of serial or taper-polishing of plan surfaces. Overall, multiple layers exhibited graded mixtures of NiO, TiO2, NiTiO3, Ni(Ti) or Pt(Ni,Ti) metal dispersoids, Ni3Ti or Pt3Ti depletion zones, and substrate, in that order. The NiTi alloy contained a 3 at.% Fe impurity that appeared in embedded localized Fe-Ti-rich oxides, while the NiPtTi alloy contained a 2 v/o dispersion of TiC that appeared in lower layers. The oxidation kinetics of both alloys (in a previous report) indicated parabolic growth and an activation energy (250 kJ/mole) near those reported in other Ti and NiTi studies. This is generally consistent with TiO2 existing as the primary scale constituent, as described here.

  6. Soil Water Cycling Links to Carbon Content between Ecosystems in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Powell, K. M.; Anderson, D. E.; Stannard, D. I.; Mladinich, C. S.; Thienelt, T. S.; Blanken, P.

    2011-12-01

    Near surface soil-water content is crucial to the sustainability of an ecosystem. Additionally, the feedbacks between soil water and soil carbon improve the ability to predict carbon sequestration rates. Organic-carbon content in surface soils influences soil texture and, subsequently, water holding capacity. Preliminary research for two growing seasons (2010 and 2011) compares soil water, temperature, heat flux, and evapotranspiration (ET) with soil organic carbon content at several sites in the Colorado Front Range. Continuous measurements of precipitation, soil moisture and temperature, and energy fluxes were conducted from eddy covariance flux towers at three sites around metropolitan Denver: one urban site and two adjacent sites, a montane forest (Flying J Ranch Open Space), and a native tallgrass prairie (Rocky Flats National Wildlife Refuge (NWR)). Irrigation data were obtained for the Denver urban site and added to its precipitation to obtain total water inputs. Soil samples (0-5cm) were collected at each tower site and analyzed for bulk density, volumetric water content, and organic carbon content. Soil water inputs and losses (as ET) were analyzed for each site and compared to soil organic carbon content. Rocky Flats NWR soils contained the highest organic carbon content (20-30 percent), while the urban site and Flying J Ranch soils contained between 10-15 percent. Comparing grassland sites, the urban soil received 5 times higher water input (600mm, more than half from irrigation) in 2010 than those of Rocky Flats. Despite less water input, the Rocky Flats site developed more soil organic carbon, possibly due to large amounts of grassland biomass mineralization and moderate soil moisture conditions through the season. The Denver urban site demonstrated less soil moisture variability in response to surface-water inputs from precipitation compared to soils at the native grassland and montane sites, perhaps limiting the conditions under which soil carbon

  7. Effects of tantalum content on the microstructure and mechanical properties of low-carbon RAFM steel

    NASA Astrophysics Data System (ADS)

    Chen, Jianguo; Liu, Chenxi; Liu, Yongchang; Yan, Biyu; Li, Huijun

    2016-10-01

    In order to explore the influence of tantalum content on the microstructure and mechanical properties of low carbon RAFM (reduced activation ferritic/martensitic) steels, three low carbon RAFM steels with different tantalum contents (0%, 0.027%, 0.073%) were designed. The precipitation behavior and effect of precipitates on the mechanical properties of the Low-C RAFM steel were investigated. The results indicate that increase of tantalum content causes decrease of the prior austenite grain size and the amount of M23C6 carbides precipitated along prior austenite grain boundaries and packet boundaries as well as increase of the amount of MX nano-sized particles within intragranular regions. The impact properties of low carbon RAFM steels are excellent regardless of the tantalum content. The impact properties and hardness are obviously improved by increasing tantalum content, which may be related to increase of the number of MX and decrease of M23C6. Furthermore, the tensile properties at elevated temperature below 600 °C are hardly changed with increase of tantalum content, yet those at 800 °C are improved with increasing tantalum content. This implies that MX carbides would be more important for tensile properties at higher temperature.

  8. Factors and processes governing the C-14 content of carbonate in desert soils

    NASA Technical Reports Server (NTRS)

    Amundson, Ronald; Wang, Yang; Chadwick, Oliver; Trumbore, Susan; Mcfadden, Leslie; Mcdonald, Eric; Wells, Steven; Deniro, Michael

    1994-01-01

    A model is presented describing the factors and processes which determine the measured C-14 ages of soil calcium carbonate. Pedogenic carbonate forms in isotopic equilium with soil CO2. Carbon dioxide in soils is a mixture of CO2 derived from two biological sources: respiration by living plant roots and respiration of microorganisms decomposing soil humus. The relative proportion of these two CO2 sources can greatly affect the initial C-14 content of pedogenic carbonate: the greater the contribution of humus-derived CO2, the greater the initial C-14 age of the carbonate mineral. For any given mixture of CO2 sources, the steady-state (14)CO2 distribution vs. soil depth can be described by a production/diffusion model. As a soil ages, the C-14 age of soil humus increases, as does the steady-state C-14 age of soil CO2 and the initial C-14 age of any pedogenic carbonate which forms. The mean C-14 age of a complete pedogenic carbonate coating or nodule will underestimate the true age of the soil carbonate. This discrepancy increases the older a soil becomes. Partial removal of outer (and younger) carbonate coatings greatly improves the relationship between measured C-14 age and true age. Although the production/diffusion model qualitatively explains the C-14 age of pedogenic carbonate vs. soil depth in many soils, other factors, such as climate change, may contribute to the observed trends, particularily in soils older than the Holocene.

  9. Damping of Selective-Laser-Melted NiTi for Medical Implants

    NASA Astrophysics Data System (ADS)

    de Wild, Michael; Meier, Fabian; Bormann, Therese; Howald, Chaim B. C.; Müller, Bert

    2014-07-01

    NiTi exhibits distinct damping properties associated with the martensite-austenite transformation. We fabricated net-shape NiTi parts layer-by-layer using a laser beam that locally melted the NiTi powder. The damping properties of such NiTi parts were analyzed by the decay of cantilever vibrations in comparison to conventionally prepared NiTi. The dynamic modulus as a function of the temperature was derived from the resonant frequency. We found that the two cantilevers showed a damping ratio of about 0.03 at temperatures below austenite start, maximal values of up to 0.04 in the transformation regions and low values of about 0.005 above austenite finish. The results indicate that selective-laser-melted NiTi qualifies for the fabrication of shock-absorbing medical implants in the same manner than conventionally produced NiTi.

  10. Snapshot prediction of carbon productivity, carbon and protein content in a Southern Ocean diatom using FTIR spectroscopy.

    PubMed

    Sackett, Olivia; Petrou, Katherina; Reedy, Brian; Hill, Ross; Doblin, Martina; Beardall, John; Ralph, Peter; Heraud, Philip

    2016-02-01

    Diatoms, an important group of phytoplankton, bloom annually in the Southern Ocean, covering thousands of square kilometers and dominating the region's phytoplankton communities. In their role as the major food source to marine grazers, diatoms supply carbon, nutrients and energy to the Southern Ocean food web. Prevailing environmental conditions influence diatom phenotypic traits (for example, photophysiology, macromolecular composition and morphology), which in turn affect the transfer of energy, carbon and nutrients to grazers and higher trophic levels, as well as oceanic biogeochemical cycles. The paucity of phenotypic data on Southern Ocean phytoplankton limits our understanding of the ecosystem and how it may respond to future environmental change. Here we used a novel approach to create a 'snapshot' of cell phenotype. Using mass spectrometry, we measured nitrogen (a proxy for protein), total carbon and carbon-13 enrichment (carbon productivity), then used this data to build spectroscopy-based predictive models. The models were used to provide phenotypic data for samples from a third sample set. Importantly, this approach enabled the first ever rate determination of carbon productivity from a single time point, circumventing the need for time-series measurements. This study showed that Chaetoceros simplex was less productive and had lower protein and carbon content during short-term periods of high salinity. Applying this new phenomics approach to natural phytoplankton samples could provide valuable insight into understanding phytoplankton productivity and function in the marine system.

  11. Effect of Alloying, Heat Treatment and Carbon Content on White Layer Formation in Machining of Steels

    SciTech Connect

    Han, Sangil; Melkote, Shreyes N; Riester, Laura

    2005-01-01

    This paper describes an experimental investigation of the effects of alloying, carbon content, and heat treatment on white layer formation in machining of steels. The investigation is carried out by machining steels that differ in alloying, heat treatment and carbon content, via orthogonal cutting tests performed with low cBN content tools. The depth of white layer and its hardness are measured for every case. Specifically, the thickness and hardness of white layer produced in cutting AISI 1045 and AISI 4340 annealed steels are compared to determine the effect of alloying on white layer formation. The effect of heat treatment on white layer formation and its hardness are investigated by machining annealed and hardened (53 HRC) AISI 4340 steels. The effect of carbon content on white layer formation is investigated by cutting hardened AISI 52100 and AISI 4340 steels of the same hardness (53 HRC). The results of the study show that alloying, heat treatment, and carbon content influence white layer formation and its hardness.

  12. The Isiokpo oil-pipeline leakage: total organic carbon/organic matter contents of affected soils.

    PubMed

    Osuji, Leo C; Adesiyan, Samuel O

    2005-08-01

    The environmental impact of the 1997 leakage of the high-pressure crude-oil pipeline at Isiokpo in the Niger Delta in the southeast of Nigeria was evaluated, with particular reference to total-organic-carbon (TOC) and total-organic-matter (TOM) contents of soils within the vicinity of the oil spillage. The soils, taken from depths of 0-15 cm (surface) and 15-30 cm (subsurface), were found to be more acidic (pH 4.2-5.6) than the unpolluted soils, with a high average moisture content of 6.8%. The extractable hydrocarbon content ranged from 2.71-3.48 mg/kg, indicating hydrocarbon contamination. However, contrary to expectation, the TOC and TOM contents of the polluted soils did not show any significant increase in concentration, supposedly due to natural rehabilitation of the affected mat layer of soils. Thus, notwithstanding the possible proliferation of heterotrophic organisms by the presence of the added petroleum hydrocarbons, environmental conditions such as weathering and climatic predispositions, as well as physico-chemical parameters such as pH, moisture content, and temperature must have encumbered the carbon-mineralizing capacity of the heterotrophs, thereby reducing the turnover of carbon and the decomposition of organic matter. The restrictions by high moisture content might not come directly from H(2)O itself, but are probably a consequence of hindered soil ventilation, which reduces O(2) supply and gaseous diffusion, conditions that might have been substantially aggravated by the added petroleum hydrocarbons.

  13. Influence of Ni on Martensitic Phase Transformations in NiTi Shape Memory Alloys

    SciTech Connect

    Frenzel, J.; George, Easo P; Dlouhy, A.; Somsen, Ch.; Wagner, M. F.-X; Eggeler, G.

    2010-01-01

    High-precision data on phase transformation temperatures in NiTi, including numerical expressions for the effect of Ni on M{sub S}, M{sub F}, A{sub S}, A{sub F} and T{sub 0}, are obtained, and the reasons for the large experimental scatter observed in previous studies are discussed. Clear experimental evidence is provided confirming the predictions of Tang et al. 1999 regarding deviations from a linear relation between the thermodynamic equilibrium temperature and Ni concentration. In addition to affecting the phase transition temperatures, increasing Ni contents are found to decrease the width of thermal hysteresis and the heat of transformation. These findings are rationalized on the basis of the crystallographic data of Prokoshkin et al. 2004 and the theory of Ball and James. The results show that it is important to document carefully the details of the arc-melting procedure used to make shape memory alloys and that, if the effects of processing are properly accounted for, precise values for the Ni concentration of the NiTi matrix can be obtained.

  14. [Effects of different fertilization modes on paddy field topsoil organic carbon content and carbon sequestration duration in South China].

    PubMed

    Zhu, Li-Qun; Yang, Min-Fang; Xu, Min-Lun; Zhang, Wu-Yi; Bian, Xin-Min

    2012-01-01

    Based on the organic carbon data of 222 topsoil samples taken from 38 paddy field experiment sites in South China, calculations were made on the relative annual change of topsoil organic carbon content (RAC) and carbon sequestration duration in the paddy fields in South China under five fertilization modes (inorganic nitrogen fertilization, N; inorganic nitrogen and phosphorus fertilization, NP; inorganic nitrogen, phosphorus, and potassium fertilization, NPK; organic fertilization, O; and inorganic plus organic fertilization, OF). The RAC under the fertilizations was 0-0.4 g x kg(-1) x a(-1), with an increment of 0.20 and 0.26 g x kg(-1) x a(-1) in double and triple cropping systems, respectively. The RAC was higher in treatments O and OF than in treatments N, NP, and NPK, being the highest (0.32 g x kg(-1) x a(-1)) in treatment OF. The topsoil organic carbon accumulation rate decreased with increasing time, and the carbon sequestration duration in treatments N, NP, NPK, O, and OF was about 22, 28, 38, 57, and 54 years, respectively. Inorganic plus organic fertilization was the most effective practice for soil carbon sequestration in the paddy fields in South China.

  15. Selective Tumor Cell Inhibition Effect of Ni-Ti Layered Double Hydroxides Thin Films Driven by the Reversed pH Gradients of Tumor Cells.

    PubMed

    Wang, Donghui; Ge, Naijian; Li, Jinhua; Qiao, Yuqin; Zhu, Hongqin; Liu, Xuanyong

    2015-04-22

    Nitinol is widely fabricated as stents for the palliation treatment of many kinds of cancers. It is of great importance to develop nitinol stents with selective tumor cell inhibition effects. In this work, a series of pH sensitive films composed of Ni(OH)2 and Ni-Ti layered double hydroxide (Ni-Ti LDH) with different Ni/Ti ratios were prepared on the surface of nitinol via hydrothermal treatment. The films with specific Ni/Ti ratios would release a large amount of nickel ions under acidic environments but were relatively stable in neutral or weak alkaline medium. Cell viability tests showed that the films can effectively inhibit the growth of cancer cells but have little adverse effects to normal cells. Besides, extraordinarily high intracellular nickel content and reactive oxygen species (ROS) level were found in cancer cells, indicating the death of cancer cells may be induced by the excessive intake of nickel ions. Such selective cancer cell inhibition effect of the films is supposed to relate with the reversed pH gradients of tumor cells.

  16. Residue removal and climatic effects on soil carbon content of no-till soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While no-till management practices usually result in increased soil organic carbon (SOC) contents, the effect of residue removal with no-till is not well understood, especially in warmer climates. A multi-year study was conducted at six locations having a wide range of climatic conditions in centra...

  17. Co-substitution of carbonate and fluoride in hydroxyapatite: Effect on substitution type and content

    NASA Astrophysics Data System (ADS)

    Zhu, Qing-Xia; Li, Ya-Ming; Han, Dan

    2015-04-01

    The nanosized hydroxyapatite substituted by fluoride and carbonate ions (CFHA) had been synthesized by aqueous precipitation method. CFHA had been considered as potential bone graft material for orthopedic and dental applications. The objective of this study was to determine the effects of simultaneously incorporated CO{3/2-} and F- on the substitution type and content. The morphologies of CFHAs were observed by TEM. The carbonate substitution type and content were characterized by FTIR. The fluoride contents were determined by F-selective electrode. The phase compositions and crystallinity of the samples were investigated by XRD. The fluoride and carbonate contents of CFHA increase with the dopant concentrations nonlinearly. The carbonate substitution has much more obvious effect on morphology compared with the fluoride substitution. The co-existence of CO{3/2-} and F- ions can influence the corresponding substitution fraction. The isomorphic substitution of sodium for calcium in the substitution process of CO{3/2-} can improve crystal degree and favor the B-type substitutions. Due to the closeness of the ion radii and equivalent substitution of F- and OH-, F- will occupy the OH- sites of HA crystals more easily, compelling most of the CO{3/2-} to be located in the B sites.

  18. Relationships between the cell volume and the carbon content of bacteria

    NASA Astrophysics Data System (ADS)

    Romanova, N. D.; Sazhin, A. F.

    2010-08-01

    The bacterial biomass is an essential point in microbial ecology. The dry weight and carbon content of microorganisms are traditionally used for the calculation of the fluxes of carbon and energy in aquatic ecosystems. Since direct measurements of these parameters in natural conditions are rather difficult, a certain biomass-carbon converting factor is used, which is determined experimentally or by empirical calculations. However, the relationship between the cell volume and its dry weight (in particular, carbon) does not depend only on the cell size and the conditions of its growth but also on the fixation and staining methods used. We made an attempt to summarize all the present data on the relationships between the cell volume, its dry weight, and the carbon content. Thus, the principal goal of the present study was searching for a generally applicable or methodology-dependent converting factor for the bacterial biomass calculation. Thereto, all the data available were grouped according to the dye used, as well as to the methods of fixation and the dry weight determination. The data on the most frequent combinations of dies and fixatives are insufficient for precise calculations; therefore, we suggest a relationship generalized for different methods of carbon and cell volume recalculations and applicable for bacterial cells larger than 0.025 μm3, as fgC cell-1 = 133.754 × V 0.438.

  19. Performance of NiTi endodontic instrument under different temperatures.

    PubMed

    Jamleh, Ahmed; Yahata, Yoshio; Ebihara, Arata; Atmeh, Amre R; Bakhsh, Turki; Suda, Hideaki

    2016-09-01

    The purpose of this study was to test nickel titanium (NiTi) instrument performance under different surrounding temperatures. Twenty-four superelastic NiTi instruments with a conical shape comprising a 0.30-mm-diameter tip and 0.06 taper were equally divided into 3 groups according to the temperature employed. Using a specially designed cyclic fatigue testing apparatus, each instrument was deflected to give a curvature 10 mm in radius and a 30° angle. This position was kept as the instrument was immersed in a continuous flow of water under a temperature of 10, 37, or 50 °C for 20 s to calculate the deflecting load (DL). In the same position, the instrument was then allowed to rotate at 300 rpm to fracture, and the working time was converted to the number of cycles to fracture (NCF). The statistical significance was set at p = 0.05. The mean DL (in N) and NCF (in cycles) of the groups at 10, 37, and 50 °C were 10.16 ± 1.36 and 135.50 ± 31.48, 13.50 ± 0.92 and 89.20 ± 16.44, and 14.70 ± 1.21 and 65.50 ± 15.90, respectively. The group at 10 °C had significantly the lowest DL that favorably resulted in the highest NCF. Within the limitations of this study, the surrounding temperature influences the cyclic fatigue resistance and DL of the superelastic NiTi instruments. Lower temperatures are found to favorably decrease the DL and extend the lifetime of the superelastic NiTi instrument. Further NiTi instrument failure studies should be performed under simulated body temperature.

  20. Caffeine content of prepackaged national-brand and private-label carbonated beverages.

    PubMed

    Chou, K-H; Bell, L N

    2007-08-01

    Caffeine is a well-known stimulant that is added as an ingredient to various carbonated soft drinks. Due to its stimulatory and other physiological effects, individuals desire to know the exact amount of caffeine consumed from these beverages. This study analyzed the caffeine contents of 56 national-brand and 75 private-label store-brand carbonated beverages using high-performance liquid chromatography. Caffeine contents ranged from 4.9 mg/12 oz (IGA Cola) to 74 mg/12 oz (Vault Zero). Some of the more common national-brand carbonated beverages analyzed in this study with their caffeine contents were Coca-Cola (33.9 mg/12 oz), Diet Coke (46.3 mg/12 oz), Pepsi (38.9 mg/12 oz), Diet Pepsi (36.7 mg/12 oz), Dr Pepper (42.6 mg/12 oz), Diet Dr Pepper (44.1 mg/12 oz), Mountain Dew (54.8 mg/12 oz), and Diet Mountain Dew (55.2 mg/12 oz). The Wal-Mart store-brand beverages with their caffeine contents were Sam's Cola (12.7 mg/12 oz), Sam's Diet Cola (13.3 mg/12 oz), Dr Thunder (30.6 mg/12 oz), Diet Dr Thunder (29.9 mg/12 oz), and Mountain Lightning (46.5 mg/12 oz). Beverages from 14 other stores were also analyzed. Most store-brand carbonated beverages were found to contain less caffeine than their national-brand counterparts. The wide range of caffeine contents in carbonated beverages indicates that consumers would benefit from the placement of caffeine values on food labels.

  1. Caffeine content of prepackaged national-brand and private-label carbonated beverages.

    PubMed

    Chou, K-H; Bell, L N

    2007-08-01

    Caffeine is a well-known stimulant that is added as an ingredient to various carbonated soft drinks. Due to its stimulatory and other physiological effects, individuals desire to know the exact amount of caffeine consumed from these beverages. This study analyzed the caffeine contents of 56 national-brand and 75 private-label store-brand carbonated beverages using high-performance liquid chromatography. Caffeine contents ranged from 4.9 mg/12 oz (IGA Cola) to 74 mg/12 oz (Vault Zero). Some of the more common national-brand carbonated beverages analyzed in this study with their caffeine contents were Coca-Cola (33.9 mg/12 oz), Diet Coke (46.3 mg/12 oz), Pepsi (38.9 mg/12 oz), Diet Pepsi (36.7 mg/12 oz), Dr Pepper (42.6 mg/12 oz), Diet Dr Pepper (44.1 mg/12 oz), Mountain Dew (54.8 mg/12 oz), and Diet Mountain Dew (55.2 mg/12 oz). The Wal-Mart store-brand beverages with their caffeine contents were Sam's Cola (12.7 mg/12 oz), Sam's Diet Cola (13.3 mg/12 oz), Dr Thunder (30.6 mg/12 oz), Diet Dr Thunder (29.9 mg/12 oz), and Mountain Lightning (46.5 mg/12 oz). Beverages from 14 other stores were also analyzed. Most store-brand carbonated beverages were found to contain less caffeine than their national-brand counterparts. The wide range of caffeine contents in carbonated beverages indicates that consumers would benefit from the placement of caffeine values on food labels. PMID:17995675

  2. Estimating the soil organic carbon content for European NUTS2 regions based on LUCAS data collection.

    PubMed

    Panagos, Panos; Ballabio, Cristiano; Yigini, Yusuf; Dunbar, Martha B

    2013-01-01

    Under the European Union Thematic Strategy for Soil Protection, the European Commission Directorate-General for the Environment and the European Environmental Agency (EEA) identified a decline in soil organic carbon and soil losses by erosion as priorities for the collection of policy relevant soil data at European scale. Moreover, the estimation of soil organic carbon content is of crucial importance for soil protection and for climate change mitigation strategies. Soil organic carbon is one of the attributes of the recently developed LUCAS soil database. The request for data on soil organic carbon and other soil attributes arose from an on-going debate about efforts to establish harmonized datasets for all EU countries with data on soil threats in order to support modeling activities and display variations in these soil conditions across Europe. In 2009, the European Commission's Joint Research Centre conducted the LUCAS soil survey, sampling ca. 20,000 points across 23 EU member states. This article describes the results obtained from analyzing the soil organic carbon data in the LUCAS soil database. The collected data were compared with the modeled European topsoil organic carbon content data developed at the JRC. The best fitted comparison was performed at NUTS2 level and showed underestimation of modeled data in southern Europe and overestimation in the new central eastern member states. There is a good correlation in certain regions for countries such as the United Kingdom, Slovenia, Italy, Ireland, and France. Here we assess the feasibility of producing comparable estimates of the soil organic carbon content at NUTS2 regional level for the European Union (EU27) and draw a comparison with existing modeled data. In addition to the data analysis, we suggest how the modeled data can be improved in future updates with better calibration of the model. PMID:23178783

  3. Estimating the soil organic carbon content for European NUTS2 regions based on LUCAS data collection.

    PubMed

    Panagos, Panos; Ballabio, Cristiano; Yigini, Yusuf; Dunbar, Martha B

    2013-01-01

    Under the European Union Thematic Strategy for Soil Protection, the European Commission Directorate-General for the Environment and the European Environmental Agency (EEA) identified a decline in soil organic carbon and soil losses by erosion as priorities for the collection of policy relevant soil data at European scale. Moreover, the estimation of soil organic carbon content is of crucial importance for soil protection and for climate change mitigation strategies. Soil organic carbon is one of the attributes of the recently developed LUCAS soil database. The request for data on soil organic carbon and other soil attributes arose from an on-going debate about efforts to establish harmonized datasets for all EU countries with data on soil threats in order to support modeling activities and display variations in these soil conditions across Europe. In 2009, the European Commission's Joint Research Centre conducted the LUCAS soil survey, sampling ca. 20,000 points across 23 EU member states. This article describes the results obtained from analyzing the soil organic carbon data in the LUCAS soil database. The collected data were compared with the modeled European topsoil organic carbon content data developed at the JRC. The best fitted comparison was performed at NUTS2 level and showed underestimation of modeled data in southern Europe and overestimation in the new central eastern member states. There is a good correlation in certain regions for countries such as the United Kingdom, Slovenia, Italy, Ireland, and France. Here we assess the feasibility of producing comparable estimates of the soil organic carbon content at NUTS2 regional level for the European Union (EU27) and draw a comparison with existing modeled data. In addition to the data analysis, we suggest how the modeled data can be improved in future updates with better calibration of the model.

  4. Variation of total organic carbon content along the stream Harsit, Eastern Black Sea Basin, Turkey.

    PubMed

    Bayram, Adem; Önsoy, Hizir; Akinci, Görkem; Bulut, Volkan Numan

    2011-11-01

    The TOC in surface waters and wastewater is an important analytical parameter describing the total content of all organic substances containing carbon. In practice, the TOC originated from natural and anthropogenic sources, and even if it is not directly responsible for dangers on human health, its determination is important for any kind of water that is used by public. The aim of this study was to determine variation of total organic carbon (TOC) and total carbon (TC) content in the stream Harsit, which courses in Eastern Black Sea Region, Turkey. Sampling was fortnightly conducted in each of the four seasons between March 2009 and February 2010. A total of 230 water samples were collected from ten sampling stations along the main branch of the stream Harsit with 143 km of length. Obtained TOC values were evaluated and used to classify the water quality of stream Harsit, according to the Turkish Water Pollution Control Regulation (TWPCR). The annual average TOC content values for the stations were found between 2.33 and 6.97 mg/L. It was seen that the TOC content have increased along the streamcourse of Harsit until the fourth station, where reaches its maximum value. The TOC content, then, has decreased and the minimum value was observed in the eighth station. The results showed that, except in winter season, maximum TOC content observed in many of the water samples were above Class I water standard indicated in TWPCR, which classifies the water resources according to the different area of uses. It was also found that TOC has a small contribution to TC and the highest TOC content in stream waters were measured in Gumushane station where direct discharge of city wastewaters and solid waste dumping to the stream were observed.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  6. Determination of fossil carbon content in Swedish waste fuel by four different methods.

    PubMed

    Jones, Frida C; Blomqvist, Evalena W; Bisaillon, Mattias; Lindberg, Daniel K; Hupa, Mikko

    2013-10-01

    This study aimed to determine the content of fossil carbon in waste combusted in Sweden by using four different methods at seven geographically spread combustion plants. In total, the measurement campaign included 42 solid samples, 21 flue gas samples, 3 sorting analyses and 2 investigations using the balance method. The fossil carbon content in the solid samples and in the flue gas samples was determined using (14)C-analysis. From the analyses it was concluded that about a third of the carbon in mixed Swedish waste (municipal solid waste and industrial waste collected at Swedish industry sites) is fossil. The two other methods (the balance method and calculations from sorting analyses), based on assumptions and calculations, gave similar results in the plants in which they were used. Furthermore, the results indicate that the difference between samples containing as much as 80% industrial waste and samples consisting of solely municipal solid waste was not as large as expected. Besides investigating the fossil content of the waste, the project was also established to investigate the usability of various methods. However, it is difficult to directly compare the different methods used in this project because besides the estimation of emitted fossil carbon the methods provide other information, which is valuable to the plant owner. Therefore, the choice of method can also be controlled by factors other than direct determination of the fossil fuel emissions when considering implementation in the combustion plants.

  7. Reduction of carbon content in waste-tire combustion ashes by bio-thermal treatment

    SciTech Connect

    Chen, C.C.; Lee, W.J.; Shih, S.I.; Mou, J.L.

    2009-07-01

    Application of bio-catalyst (NOE-7F) in thermal treatment can adequately dispose dark-black fly ashes from co-combustion of both waste tires and coal. After thermal treatment of fly ashes by adding 10% NOE-7F, the carbon contents reduced by 37.6% and the weight losses increased by 405%, compared with the fly ashes without mixing with NOE-7F. The combustion behaviors of wasted tires combustion fly ashes with NOE-7F were also investigated by both thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The results verify that NOE-7F has positive effects on the combustion of residual carbon and toxic polycyclic aromatic hydrocarbons (PAHs) enhance the energy release and reduce the toxicity during the process of thermal treatment. Furthermore, using NOE-7F to dispose high-carbon content fly ashes did improve the compressive strength of fly ashes and concrete mixtures. Therefore, NOE-7F is a promising additive which could decrease treatment cost of high-carbon content fly ashes and reduce the amount of survival toxic PAHs.

  8. Relation between PAH and black carbon contents in size fractions of Norwegian harbor sediments.

    PubMed

    Oen, Amy M P; Cornelissen, Gerard; Breedveld, Gijs D

    2006-05-01

    Distributions of total organic carbon (TOC), black carbon (BC), and polycyclic aromatic hydrocarbons (PAH) were investigated in different particle size fractions for four Norwegian harbor sediments. The total PAH (16-EPA) concentrations ranged from 2 to 113 mg/kg dry weight with the greatest fraction of PAH mass in the sand fraction for three of the four sediments. TOC contents ranged from 0.84% to 14.2% and BC contents from 0.085% to 1.7%. This corresponds to organic carbon (OC = TOC - BC) contents in the range of 0.81-14% and BC:TOC ratios of 1.3-18.1%. PAH isomer ratios suggested that the PAH in all four sediments were of pyrogenic origin. Furthermore, stronger correlations between PAH versus BC (r2 = 0.85) than versus OC (r2 = 0.15) were found. For all size fractions and bulk sediments, the PAH-to-BC ratios for the total PAHs were on average 6+/-3 mg PAH/g BC. These results suggest that PAH distributions were dominated by the presence of BC, rather than OC. As sorption to BC is much stronger than sorption to OC, this may result in significantly lower dissolved concentrations of PAH than expected on the basis of organic carbon partitioning alone. PMID:16249047

  9. [Effects of different tillage methods and straw-returning on soil organic carbon content in a winter wheat field].

    PubMed

    Tian, Shen-Zhong; Ning, Tang-Yuan; Wang, Yu; Li, Hong-Jie; Zhong, Wei-Lei; Li, Zeng-Jia

    2010-02-01

    A two growth seasons experiment was conducted to study the effects of different tillage methods, straw-returning, and their interaction on the dynamic change of organic carbon content in 0-20 cm soil layer during the whole growth period of winter wheat. An obvious change was observed in the soil organic carbon content. Treatments with straw-returning had higher soil organic carbon content than treatments with no straw-returning, and conservation tillage induced higher soil organic carbon content than conventional tillage. In all treatments except conventional tillage, the organic carbon content in 0-10 cm soil layer was higher than that in 10-20 cm soil layer. In treatments with straw-returning, the organic carbon content in 0-10 cm soil layer decreased in order of deep soiling (PS) > rotary tillage (PR) > no tillage (PZ) > normal ploughing (PH) > conventional tillage (PC), while that in 10-20 cm soil layer was PC > PS > PR > PH > PZ, suggesting that conservation tillage could improve the organic carbon content in 0-10 cm soil layer. Multi factor variance analysis showed that tillage method, straw-returning, and their interaction had significant effects on the organic carbon content in 0-20 cm soil layer at various growth stages of winter wheat.

  10. [Study on the content and carbon isotopic composition of water dissolved inorganic carbon from rivers around Xi'an City].

    PubMed

    Guo, Wei; Li, Xiang-Zhong; Liu, Wei-Guo

    2013-04-01

    In this study, the content and isotopic compositions of water dissolved inorganic carbon (DIC) from four typical rivers (Chanhe, Bahe, Laohe and Heihe) around Xi'an City were studied to trace the possible sources of DIC. The results of this study showed that the content of DIC in the four rivers varied from 0.34 to 5.66 mmol x L(-1) with an average value of 1.23 mmol x L(-1). In general, the content of DIC increased from the headstream to the river mouth. The delta13C(DIC) of four rivers ranged from -13.3 per thousand to -7.2 per thousand, with an average value of -10.1 per thousand. The delta13C(DIC) values of river water were all negative (average value of -12.6 per thousand) at the headstream of four rivers, but the delta13C(DIC) values of downstream water were more positive (with an average value of -9.4 per thousand). In addition, delta13C(DIC) of river water showed relatively negative values (the average value of delta13C(DIC) was -10.5 per thousand) near the estuary of the rivers. The variation of the DIC content and its carbon isotope suggested that the DIC sources of the rivers varied from the headstream to the river mouth. The negative delta13C(DIC) value indicated that the DIC may originate from the soil CO2 at the headstream of the rivers. On the other hand, the delta13C(DIC) values of river water at the middle and lower reaches of rivers were more positive, and it showed that soil CO2 produced by respiration of the C4 plants (like corn) and soil carbonates with positive delta13C values may be imported into river water. Meanwhile, the input of pollutants with low delta13C(DIC) values may result in a decrease of delta13C(DIC) values in the rivers. The study indicated that the DIC content and carbon isotope may be used to trace the sources of DIC in rivers around Xi'an City. Our study may provide some basic information for tracing the sources of DIC of rivers in the small watershed area in the Loess Plateau of China.

  11. Carbon content variation in boles of mature sugar maple and giant sequoia.

    PubMed

    Lamlom, Sabah H; Savidge, Rodney A

    2006-04-01

    At present, a carbon (C) content of 50% (w/w) in dry wood is widely accepted as a generic value; however, few wood C measurements have been reported. We used elemental analysis to investigate C content per unit of dry matter and observed that it varied both radially and vertically in boles of two old-growth tree species: sugar maple (Acer saccharum Marsh.) and giant sequoia (Sequoiadendron giganteum (Lindl.) Bucholz). In sugar maple there was considerable variation in tree ring widths among four radii for particular annual layers of xylem, revealing that the annual rate of C assimilation differs around the circumference and from the base of each tree to its top, but the observed variation in C content was unrelated to diameter growth rate and strongly related to the calendar year when the wood was formed. Carbon content in sugar maple wood increased in an approximately linear fashion, from < 50 to 51% from pith to cambium, at both the base and top of the boles. In giant sequoia, C was essentially constant at > 55% across many hundreds of years of heartwood, but it declined abruptly at the sapwood-heartwood boundary and remained lower in all sapwood samples, an indication that heartwood formation involves anabolic metabolism. Factors that may be responsible for the different C contents and trends with age between sugar maple and sequoia trees are considered. Tree-ring data from this study do not support some of the key assumptions made by dendrochronology.

  12. Carbon content variation in boles of mature sugar maple and giant sequoia.

    PubMed

    Lamlom, Sabah H; Savidge, Rodney A

    2006-04-01

    At present, a carbon (C) content of 50% (w/w) in dry wood is widely accepted as a generic value; however, few wood C measurements have been reported. We used elemental analysis to investigate C content per unit of dry matter and observed that it varied both radially and vertically in boles of two old-growth tree species: sugar maple (Acer saccharum Marsh.) and giant sequoia (Sequoiadendron giganteum (Lindl.) Bucholz). In sugar maple there was considerable variation in tree ring widths among four radii for particular annual layers of xylem, revealing that the annual rate of C assimilation differs around the circumference and from the base of each tree to its top, but the observed variation in C content was unrelated to diameter growth rate and strongly related to the calendar year when the wood was formed. Carbon content in sugar maple wood increased in an approximately linear fashion, from < 50 to 51% from pith to cambium, at both the base and top of the boles. In giant sequoia, C was essentially constant at > 55% across many hundreds of years of heartwood, but it declined abruptly at the sapwood-heartwood boundary and remained lower in all sapwood samples, an indication that heartwood formation involves anabolic metabolism. Factors that may be responsible for the different C contents and trends with age between sugar maple and sequoia trees are considered. Tree-ring data from this study do not support some of the key assumptions made by dendrochronology. PMID:16414925

  13. Bonding and hardness in nonhydrogenated carbon films with moderate sp{sup 3} content

    SciTech Connect

    Gago, R.; Jimenez, I.; Albella, J. M.; Climent-Font, A.; Caceres, D.; Vergara, I.; Banks, J. C.; Doyle, B. L.; Terminello, L. J.

    2000-06-01

    Amorphous carbon films with an sp{sup 3} content up to 25% and a negligible amount of hydrogen have been grown by evaporation of graphite with concurrent Ar{sup +} ion bombardment. The sp{sup 3} content is maximized for Ar{sup +} energies between 200 and 300 eV following a subplantation mechanism. Higher ion energies deteriorate the film due to sputtering and heating processes. The hardness of the films increases in the optimal assisting range from 8 to 18 GPa, and is explained by crosslinking of graphitic planes through sp{sup 3} connecting sites. (c) 2000 American Institute of Physics.

  14. The Effects of Simulated Wildfire on Particle Size and Carbon Content in Piedmont Soils.

    NASA Astrophysics Data System (ADS)

    Wynes, A.; Werts, S. P.

    2014-12-01

    Soils are a known carbon sink, holding twice as much carbon as the atmosphere (Schlesinger, 1995). However, little is known about how much soil organic carbon (SOC) is released from the soil during fire events. Surface fires can heat mineral soils to up to 500°C at depths of several centimeters and maintain that temperature for hours (Werts and Jahren, 2007). This has been known to affect the size of particles in soils, carbon content in the soils, and the clay mineralogy (Hungerford et al, 1993). This study looks at relationships between soil clay content and clay chemistry in relation to carbon emissions during surface fires, to determine temperature effects on several piedmont soil types from South Carolina. Soil samples were taken from three different sites varying in clay content, clay type, parent material, and development. Temperature increases were applied in increments of 50°C, with a range from 100°C to 500°C, to determine fire effects on SOC, particle size, and clay mineralogy of the soils. We found a decrease in SOC (up to 98%) from the original amount in all soil horizons with temperature applications up to 500°C. At a temperature range between 100°C and 300°C, most soil horizons showed an increase in clay of a range between 0.1 and 34%. At temperatures ranging from 300°C to 500°C, there was a decrease in clay ranging from 2.5-42%. While previous research suggests that a positive correlation between the percentage of clay and SOC in soils is common (Feller and Beare, 1997), in this study, a negative correlation was found between the percentage of clay and SOC in all three soil types (R2=0.87, 0.76, and 0.59) at 100°C. There appears to be an increasingly positive relationship between clay and carbon as temperature increases, although a consistent high correlation was not present at all temperatures. This is counter to what was found initially in our soils prior to heating. While research into surface fires is important to the understanding of

  15. Current activated tip sintering of Ni-Ti intermetallics

    NASA Astrophysics Data System (ADS)

    Sharma, Nitin

    This thesis investigated the current activated tip-sintering of reactive mixtures of nickel and titanium to form Ni-Ti intermetallics. The effect of elemental powder composition, heating profile and micro-jet inert gas pressures on the developed macro- and microstructure was investigated. The heating profile brought upon by selective electric current application was found to have a significant effect on whether the reaction is a volumetric combustion or a self-propagating high temperature one. The best results in terms of homogeneity and Ni-Ti intermetallics yield, were obtained for an inert gas pressure of 4 psi under for the nickel rich composition. In addition, surprising results at the higher inert gas pressures show the formation of hollow products, which can give rise future exploration of this technique for combustion synthesizing hollow products of different shapes.

  16. The tribocorrosion behaviour of NiTi alloy

    NASA Astrophysics Data System (ADS)

    Kosec, Tadeja; Močnik, Petra; Legat, Andraž

    2014-01-01

    In biomedical applications, NiTi alloys are used mainly because of their favourable shape memory and superelastic properties. However, in many applications the tribocorrosion properties of these alloys can be of critical concern. For this reason the electrochemical and tribocorrosion properties of superelastic NiTi sheet and orthodontic archwire were studied, taking into account their microstructures and the effect of different surface finishes. In the case of the electrochemical tests, samples were tested in artificial saliva, whereas in the tribocorrosion tests the experiments were performed in ambient air, distilled water, and artificial saliva, the latter as a corrosive medium. In these tests, the total wear rate of the alloy samples was determined, together with the corresponding chemical and tribological contributions. It was confirmed that the microstructure of the investigated alloys had a significant effect on the measured electrochemical and tribocorrosion properties.

  17. NiTi bonded space regainer/maintainer.

    PubMed

    Negi, K S

    2010-01-01

    Early orthodontic interventions are often initiated in the developing dentition to promote favorable developmental changes. Interceptive orthodontic can eliminate or reduce the severity of a developing malocclusion, the complexity of orthodontic treatment, overall treatment time and cost. Premature loss of deciduous tooth or teeth can often destroy the integrity of normal occlusion. There are many space regaining and maintaining devices mentioned in literature. In this article, I present a simple space regaining method by a piece of nickel titanium (NiTi) wire bonded between the teeth in active loop form, and the unique shape memory property of NiTi wire will upright or move the teeth and the lost space can be regained easily.

  18. Digital mapping of soil organic carbon contents and stocks in Denmark.

    PubMed

    Adhikari, Kabindra; Hartemink, Alfred E; Minasny, Budiman; Bou Kheir, Rania; Greve, Mette B; Greve, Mogens H

    2014-01-01

    Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0-5, 5-15, 15-30, 30-60 and 60-100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg(-1) was reported for 0-5 cm soil, whereas there was on average 2.2 g SOC kg(-1) at 60-100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg(-1) was found at 60-100 cm soil depth. Average SOC stock for 0-30 cm was 72 t ha(-1) and in the top 1 m there was 120 t SOC ha(-1). In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories.

  19. Fructose content and composition of commercial HFCS-sweetened carbonated beverages

    PubMed Central

    White, J S; Hobbs, L J; Fernandez, S

    2015-01-01

    Objective: The obesigenic and related health effects of caloric sweeteners are subjects of much current research. Consumers can properly adjust their diets to conform to nutritional recommendations only if the sugars composition of foods and beverages is accurately measured and reported, a matter of recent concern. We tested the hypothesis that high-fructose corn syrup (HFCS) used in commercial carbonated beverages conforms to commonly assumed fructose percentages and industry technical specifications, and fulfills beverage product label regulations and Food Chemicals Codex-stipulated standards. Design: A high-pressure liquid chromatography method was developed and verified for analysis of sugars in carbonated beverages sweetened with HFCS-55. The method was used to measure percent fructose in three carbonated beverage categories. Method verification was demonstrated by acceptable linearity (R2>0.99), accuracy (94–104% recovery) and precision (RSD<2%). Result: Fructose comprised 55.58% of total sugars (95% confidence interval 55.51–55.65%), based on 160 total measurements by 2 independent laboratories of 80 randomly selected carbonated beverages sweetened with HFCS-55. The difference in fructose measurements between laboratories was significant but small (0.1%), and lacked relevance. Differences in fructose by product category or by product age were not statistically significant. Total sugars content of carbonated beverages showed close agreement within product categories (95% confidence interval=0.01–0.54%). Conclusions: Using verified analytical methodology for HFCS-sweetened carbonated beverages, this study confirmed the hypothesis that fructose as a percentage of total sugars is in close agreement with published specifications in industry technical data sheets, published literature values and governmental standards and requirements. Furthermore, total sugars content of commercial beverages is consistent with common industry practices for canned and

  20. Digital Mapping of Soil Organic Carbon Contents and Stocks in Denmark

    PubMed Central

    Adhikari, Kabindra; Hartemink, Alfred E.; Minasny, Budiman; Bou Kheir, Rania; Greve, Mette B.; Greve, Mogens H.

    2014-01-01

    Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0−5, 5−15, 15−30, 30−60 and 60−100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg−1 was reported for 0−5 cm soil, whereas there was on average 2.2 g SOC kg−1 at 60−100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg−1 was found at 60−100 cm soil depth. Average SOC stock for 0−30 cm was 72 t ha−1 and in the top 1 m there was 120 t SOC ha−1. In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories. PMID:25137066

  1. Martensite transformation of epitaxial Ni-Ti films

    SciTech Connect

    Buschbeck, J.; Kozhanov, A.; Kawasaki, J. K.; James, R. D.; Palmstroem, C. J.

    2011-05-09

    The structure and phase transformations of thin Ni-Ti shape memory alloy films grown by molecular beam epitaxy are investigated for compositions from 43 to 56 at. % Ti. Despite the substrate constraint, temperature dependent x-ray diffraction and resistivity measurements reveal reversible, martensitic phase transformations. The results suggest that these occur by an in-plane shear which does not disturb the lattice coherence at interfaces.

  2. Size and Carbon Content of Sub-seafloor Microbial Cells at Landsort Deep, Baltic Sea

    PubMed Central

    Braun, Stefan; Morono, Yuki; Littmann, Sten; Kuypers, Marcel; Aslan, Hüsnü; Dong, Mingdong; Jørgensen, Bo B.; Lomstein, Bente Aa.

    2016-01-01

    The discovery of a microbial ecosystem in ocean sediments has evoked interest in life under extreme energy limitation and its role in global element cycling. However, fundamental parameters such as the size and the amount of biomass of sub-seafloor microbial cells are poorly constrained. Here we determined the volume and the carbon content of microbial cells from a marine sediment drill core retrieved by the Integrated Ocean Drilling Program (IODP), Expedition 347, at Landsort Deep, Baltic Sea. To determine their shape and volume, cells were separated from the sediment matrix by multi-layer density centrifugation and visualized via epifluorescence microscopy (FM) and scanning electron microscopy (SEM). Total cell-carbon was calculated from amino acid-carbon, which was analyzed by high-performance liquid chromatography (HPLC) after cells had been purified by fluorescence-activated cell sorting (FACS). The majority of microbial cells in the sediment have coccoid or slightly elongated morphology. From the sediment surface to the deepest investigated sample (~60 m below the seafloor), the cell volume of both coccoid and elongated cells decreased by an order of magnitude from ~0.05 to 0.005 μm3. The cell-specific carbon content was 19–31 fg C cell−1, which is at the lower end of previous estimates that were used for global estimates of microbial biomass. The cell-specific carbon density increased with sediment depth from about 200 to 1000 fg C μm−3, suggesting that cells decrease their water content and grow small cell sizes as adaptation to the long-term subsistence at very low energy availability in the deep biosphere. We present for the first time depth-related data on the cell volume and carbon content of sedimentary microbial cells buried down to 60 m below the seafloor. Our data enable estimates of volume- and biomass-specific cellular rates of energy metabolism in the deep biosphere and will improve global estimates of microbial biomass.

  3. Size and Carbon Content of Sub-seafloor Microbial Cells at Landsort Deep, Baltic Sea

    PubMed Central

    Braun, Stefan; Morono, Yuki; Littmann, Sten; Kuypers, Marcel; Aslan, Hüsnü; Dong, Mingdong; Jørgensen, Bo B.; Lomstein, Bente Aa.

    2016-01-01

    The discovery of a microbial ecosystem in ocean sediments has evoked interest in life under extreme energy limitation and its role in global element cycling. However, fundamental parameters such as the size and the amount of biomass of sub-seafloor microbial cells are poorly constrained. Here we determined the volume and the carbon content of microbial cells from a marine sediment drill core retrieved by the Integrated Ocean Drilling Program (IODP), Expedition 347, at Landsort Deep, Baltic Sea. To determine their shape and volume, cells were separated from the sediment matrix by multi-layer density centrifugation and visualized via epifluorescence microscopy (FM) and scanning electron microscopy (SEM). Total cell-carbon was calculated from amino acid-carbon, which was analyzed by high-performance liquid chromatography (HPLC) after cells had been purified by fluorescence-activated cell sorting (FACS). The majority of microbial cells in the sediment have coccoid or slightly elongated morphology. From the sediment surface to the deepest investigated sample (~60 m below the seafloor), the cell volume of both coccoid and elongated cells decreased by an order of magnitude from ~0.05 to 0.005 μm3. The cell-specific carbon content was 19–31 fg C cell−1, which is at the lower end of previous estimates that were used for global estimates of microbial biomass. The cell-specific carbon density increased with sediment depth from about 200 to 1000 fg C μm−3, suggesting that cells decrease their water content and grow small cell sizes as adaptation to the long-term subsistence at very low energy availability in the deep biosphere. We present for the first time depth-related data on the cell volume and carbon content of sedimentary microbial cells buried down to 60 m below the seafloor. Our data enable estimates of volume- and biomass-specific cellular rates of energy metabolism in the deep biosphere and will improve global estimates of microbial biomass. PMID:27630628

  4. Size and Carbon Content of Sub-seafloor Microbial Cells at Landsort Deep, Baltic Sea.

    PubMed

    Braun, Stefan; Morono, Yuki; Littmann, Sten; Kuypers, Marcel; Aslan, Hüsnü; Dong, Mingdong; Jørgensen, Bo B; Lomstein, Bente Aa

    2016-01-01

    The discovery of a microbial ecosystem in ocean sediments has evoked interest in life under extreme energy limitation and its role in global element cycling. However, fundamental parameters such as the size and the amount of biomass of sub-seafloor microbial cells are poorly constrained. Here we determined the volume and the carbon content of microbial cells from a marine sediment drill core retrieved by the Integrated Ocean Drilling Program (IODP), Expedition 347, at Landsort Deep, Baltic Sea. To determine their shape and volume, cells were separated from the sediment matrix by multi-layer density centrifugation and visualized via epifluorescence microscopy (FM) and scanning electron microscopy (SEM). Total cell-carbon was calculated from amino acid-carbon, which was analyzed by high-performance liquid chromatography (HPLC) after cells had been purified by fluorescence-activated cell sorting (FACS). The majority of microbial cells in the sediment have coccoid or slightly elongated morphology. From the sediment surface to the deepest investigated sample (~60 m below the seafloor), the cell volume of both coccoid and elongated cells decreased by an order of magnitude from ~0.05 to 0.005 μm(3). The cell-specific carbon content was 19-31 fg C cell(-1), which is at the lower end of previous estimates that were used for global estimates of microbial biomass. The cell-specific carbon density increased with sediment depth from about 200 to 1000 fg C μm(-3), suggesting that cells decrease their water content and grow small cell sizes as adaptation to the long-term subsistence at very low energy availability in the deep biosphere. We present for the first time depth-related data on the cell volume and carbon content of sedimentary microbial cells buried down to 60 m below the seafloor. Our data enable estimates of volume- and biomass-specific cellular rates of energy metabolism in the deep biosphere and will improve global estimates of microbial biomass. PMID:27630628

  5. Organic carbon and nitrogen content associated with colloids and suspended particulates from the Mississippi River and some of its tributaries

    USGS Publications Warehouse

    Rostad, C.E.; Leenheer, J.A.; Daniel, S.R.

    1997-01-01

    Suspended material samples were collected at 16 sites along the Mississippi River and some of its tributaries during July-August 1991, October-November 1991, and April-May 1992, and separated into colloid and particulate fractions to determine the organic carbon content of these two fractions of suspended material. Sample collection involved centrifugation to isolate the suspended particulate fraction and ultrafiltration to isolate the colloid fraction. For the first time, particulate and colloid concentrations and organic carbon and nitrogen content were investigated along the entire reach of the Mississippi River from above Minneapolis, Minnesota, to below New Orleans, Louisiana. Organic carbon content of the colloid (15.2 percent) was much higher than organic carbon content of the particulate material (4.8 percent). Carbon/nitrogen ratios of colloid and particulate phases were more similar to ratios for microorganisms than to ratios for soils, humic materials, or plants.Suspended material samples were collected at 16 sites along the Mississippi River and some of its tributaries during July-August 1991, October-November 1991, and April-May 1992, and separated into colloid and particulate fractions to determine the organic carbon content of these two fractions of suspended material. Sample collection involved centrifugation to isolate the suspended particulate fraction and ultrafiltration to isolate the colloid fraction. For the first time, particulate and colloid concentrations and organic carbon and nitrogen content were investigated along the entire reach of the Mississippi River from above Minneapolis, Minnesota, to below New Orleans, Louisiana. Organic carbon content of the colloid (15.2 percent) was much higher than organic carbon content of the particulate material (4.8 percent). Carbon/nitrogen ratios of colloid and particulate phases were more similar to ratios for microorganisms than to ratios for soils, humic materials, or plants.

  6. The ratio of clay content to total organic carbon content is a useful parameter to predict adsorption of the herbicide butachlor in soils.

    PubMed

    Liu, Zhongzhen; He, Yan; Xu, Jianming; Huang, Panming; Jilani, Ghulam

    2008-03-01

    Thirteen soils collected from 11 provinces in eastern China were used to investigate the butachlor adsorption. The results indicated that the total organic carbon (TOC) content, clay content, amorphous Fe2O3 content, silt content, CEC, and pH had a combined effect on the butachlor sorption on soil. Combination of the data obtained from the 13 soils in the present study with other 23 soil samples reported by other researchers in the literature showed that Koc would be a poor predictive parameter for butachlor adsorption on soils with TOC content higher than 4.0% and lower than 0.2%. The soils with the ratio of clay content to TOC content (RCO) values less than 60 adsorbed butachlor mainly by the partition into soil organic matter matrix. The soils with RCO values higher than 60 apparently adsorbed butachlor by the combination of the partition into soil organic matter matrix and adsorption on clay surface.

  7. Fabrication of Ni-Ti-O nanotube arrays by anodization of NiTi alloy and their potential applications

    PubMed Central

    Hang, Ruiqiang; Liu, Yanlian; Zhao, Lingzhou; Gao, Ang; Bai, Long; Huang, Xiaobo; Zhang, Xiangyu; Tang, Bin; Chu, Paul K.

    2014-01-01

    Nickel-titanium-oxide (Ni-Ti-O) nanotube arrays (NTAs) prepared on nearly equiatomic NiTi alloy shall have broad application potential such as for energy storage and biomedicine, but their precise structure control is a great challenge because of the high content of alloying element of Ni, a non-valve metal that cannot form a compact electronic insulating passive layer when anodized. In the present work, we systemically investigated the influence of various anodization parameters on the formation and structure of Ni-Ti-O NTAs and their potential applications. Our results show that well controlled NTAs can be fabricated during relatively wide ranges of the anodization voltage (5–90 V), electrolyte temperature (10–50°C) and electrolyte NH4F content (0.025–0.8 wt%) but within a narrow window of the electrolyte H2O content (0.0–1.0 vol%). Through modulating these parameters, the Ni-Ti-O NTAs with different diameter (15–70 nm) and length (45–1320 nm) can be produced in a controlled manner. Regarding potential applications, the Ni-Ti-O NTAs may be used as electrodes for electrochemical energy storage and non-enzymic glucose detection, and may constitute nanoscaled biofunctional coating to improve the biological performance of NiTi based biomedical implants. PMID:25520180

  8. Fabrication of Ni-Ti-O nanotube arrays by anodization of NiTi alloy and their potential applications

    NASA Astrophysics Data System (ADS)

    Hang, Ruiqiang; Liu, Yanlian; Zhao, Lingzhou; Gao, Ang; Bai, Long; Huang, Xiaobo; Zhang, Xiangyu; Tang, Bin; Chu, Paul K.

    2014-12-01

    Nickel-titanium-oxide (Ni-Ti-O) nanotube arrays (NTAs) prepared on nearly equiatomic NiTi alloy shall have broad application potential such as for energy storage and biomedicine, but their precise structure control is a great challenge because of the high content of alloying element of Ni, a non-valve metal that cannot form a compact electronic insulating passive layer when anodized. In the present work, we systemically investigated the influence of various anodization parameters on the formation and structure of Ni-Ti-O NTAs and their potential applications. Our results show that well controlled NTAs can be fabricated during relatively wide ranges of the anodization voltage (5-90 V), electrolyte temperature (10-50°C) and electrolyte NH4F content (0.025-0.8 wt%) but within a narrow window of the electrolyte H2O content (0.0-1.0 vol%). Through modulating these parameters, the Ni-Ti-O NTAs with different diameter (15-70 nm) and length (45-1320 nm) can be produced in a controlled manner. Regarding potential applications, the Ni-Ti-O NTAs may be used as electrodes for electrochemical energy storage and non-enzymic glucose detection, and may constitute nanoscaled biofunctional coating to improve the biological performance of NiTi based biomedical implants.

  9. Exploring the multiplicity of soil-human interactions: organic carbon content, agro-forest landscapes and the Italian local communities.

    PubMed

    Salvati, Luca; Barone, Pier Matteo; Ferrara, Carlotta

    2015-05-01

    Topsoil organic carbon (TOC) and soil organic carbon (SOC) are fundamental in the carbon cycle influencing soil functions and attributes. Many factors have effects on soil carbon content such as climate, parent material, land topography and the human action including agriculture, which sometimes caused a severe loss in soil carbon content. This has resulted in a significant differentiation in TOC or SOC at the continental scale due to the different territorial and socioeconomic conditions. The present study proposes an exploratory data analysis assessing the relationship between the spatial distribution of soil organic carbon and selected socioeconomic attributes at the local scale in Italy with the aim to provide differentiated responses for a more sustainable use of land. A strengths, weaknesses, opportunities and threats (SWOT) analysis contributed to understand the effectiveness of local communities responses for an adequate comprehension of the role of soil as carbon sink. PMID:25903408

  10. Exploring the multiplicity of soil-human interactions: organic carbon content, agro-forest landscapes and the Italian local communities.

    PubMed

    Salvati, Luca; Barone, Pier Matteo; Ferrara, Carlotta

    2015-05-01

    Topsoil organic carbon (TOC) and soil organic carbon (SOC) are fundamental in the carbon cycle influencing soil functions and attributes. Many factors have effects on soil carbon content such as climate, parent material, land topography and the human action including agriculture, which sometimes caused a severe loss in soil carbon content. This has resulted in a significant differentiation in TOC or SOC at the continental scale due to the different territorial and socioeconomic conditions. The present study proposes an exploratory data analysis assessing the relationship between the spatial distribution of soil organic carbon and selected socioeconomic attributes at the local scale in Italy with the aim to provide differentiated responses for a more sustainable use of land. A strengths, weaknesses, opportunities and threats (SWOT) analysis contributed to understand the effectiveness of local communities responses for an adequate comprehension of the role of soil as carbon sink.

  11. Tillage, cropping sequence, and nitrogen fertilization effects on dryland soil carbon dioxide emission and carbon content.

    PubMed

    Sainju, Upendra M; Jabro, Jalal D; Caesar-Tonthat, Thecan

    2010-01-01

    Management practices are needed to reduce dryland soil CO(2) emissions and to increase C sequestration. We evaluated the effects of tillage and cropping sequence combinations and N fertilization on dryland crop biomass (stems + leaves) and soil surface CO(2) flux and C content (0- to 120-cm depth) in a Williams loam from May to October, 2006 to 2008, in eastern Montana. Treatments were no-tilled continuous malt barley (Hordeum vulgaris L.) (NTCB), no-tilled malt barley-pea (Pisum sativum L.) (NTB-P), no-tilled malt barley-fallow (NTB-F), and conventional-tilled malt barley-fallow (CTB-F), each with 0 and 80 kg N ha(-1). Measurements were made both in Phase I (malt barley in NTCB, pea in NTB-P, and fallow in NTB-F and CTB-F) and Phase II (malt barley in all sequences) of each cropping sequence in every year. Crop biomass varied among years, was greater in the barley than in the pea phase of the NTB-P treatment, and greater in NTCB and NTB-P than in NTB-F and CTB-F in 2 out of 3 yr. Similarly, biomass was greater with 80 than with 0 kg N ha(-1) in 1 out of 3 yr. Soil CO(2) flux increased from 8 mg C m(-2) h(-1) in early May to 239 mg C m(-2) h(-1) in mid-June as temperature increased and then declined to 3 mg C m(-2) h(-1) in September-October. Fluxes peaked immediately following substantial precipitation (>10 mm), especially in NTCB and NTB-P. Cumulative CO(2) flux from May to October was greater in 2006 and 2007 than in 2008, greater in cropping than in fallow phases, and greater in NTCB than in NTB-F. Tillage did not influence crop biomass and CO(2) flux but N fertilization had a variable effect on the flux in 2008. Similarly, soil total C content was not influenced by treatments. Annual cropping increased CO(2) flux compared with crop-fallow probably by increasing crop residue returns to soils and root and rhizosphere respiration. Inclusion of peas in the rotation with malt barley in the no-till system, which have been known to reduce N fertilization rates and

  12. Increasing carbon content of fly ash: Consequences and recovery of lost value

    SciTech Connect

    Willauer, C.S.; Gasiorowski, S.A.

    1999-07-01

    In response to Phase 2 of the Clean Air Act of 1990, US electric utilities operating coal fired power plants are currently installing low NO {sub x} equipment to meet new air emissions requirements. As these plants begin to operate under the lower NO{sub x} requirements, more carbon remains in the plant's fly ash (a by-product of coal combustion) often exceeding the maximum allowable carbon content of 6% for use in concrete. The carbon content of the fly ash can be further elevated by alternate fuel strategies. As utilities continue to seek improvements in fuel economies by purchase of foreign coals and alternate fuels such as petroleum coke, the resulting carbon level of the fly ash can increase dramatically due to the combustion characteristics of these materials. While considerable reduction in fuel costs are possible, the variable, high-carbon fly ash must be disposed in landfills or used in low value, non-concrete applications. For utilities that have become accustomed to marketing the majority of their coal combustion products (CCPs) land filling is a highly unsatisfactory alternative. Recently, the American Coal Ash Association conducted a survey of electric-utilities to determine the impact of NOx reduction strategies on the marketability of rendered unusable for concrete markets. Shortage of fly ash, particularly fly ashes derived from eastern bituminous coals (Class F-ash) have occurred in the eastern US. This fact combined with the increased demand for cement in the same region has pushed prices higher for concrete grade, high-quality fly ash. Renewed interest has thus developed in processes to restore the value of the high-LOI fly ash.

  13. Effect of titanium on the creep deformation behaviour of 14Cr-15Ni-Ti stainless steel

    NASA Astrophysics Data System (ADS)

    Latha, S.; Mathew, M. D.; Parameswaran, P.; Nandagopal, M.; Mannan, S. L.

    2011-02-01

    14Cr-15Ni-Ti modified stainless steel alloyed with additions of phosphorus and silicon is a potential candidate material for the future cores of Prototype Fast Breeder Reactor. In order to optimise the titanium content in this steel, creep tests have been conducted on the heats with different titanium contents of 0.18, 0.23, 0.25 and 0.36 wt.% at 973 K at various stress levels. The stress exponents indicated that the rate controlling deformation mechanism was dislocation creep. A peak in the variation of rupture life with titanium content was observed around 0.23 wt.% titanium and the peak was more pronounced at lower stresses. The variation in creep strength with titanium content was correlated with transmission electron microscopic investigations. The peak in creep strength exhibited by the material with 0.23 wt.% titanium is attributed to the higher volume fraction of fine secondary titanium carbide (TiC) precipitates.

  14. Land abandonment, fire recurrence and soil carbon content in the Macizo del Caroig, Eastern Spain

    NASA Astrophysics Data System (ADS)

    Cerdá, A.; González Peñaloza, F.; Santín, C.; Doerr, S. H.

    2012-04-01

    During the last 50 years two main forces have driven the fate of Mediterranean landscapes: land abandonment and forest fires (MacDonald et al., 2000; Moreira et al., 2001). Due to the economical changes suffered by the of the Mediterranean countries after the Second World War, the population migrated from the rural to the urban areas, and from South to North Europe. The land abandonment allowed the vegetation to recover and, as a consequence, an increase in forest fire took place. The soils of the abandoned land recovered the vegetation and litter layers, and consequently changes in soil properties have being found. One of these changes is the increase of soil carbon content, which is due both to vegetation recovery and to fire occurrence that increases the ash and pyrogenic carbon content in soils. Twenty plots were selected in the Macizo del Caroig in Eastern Spain on soils developed on limestone. The period of abandonment and the forest fires that had affected each plot were determined by interviews with the owners, farmers and shepherds. In addition, six (three + three) plots were selected as forest (no plough) and cultivated control plots. Each plot was sampled (10 random samples) and the organic carbon content determined. The results show that the cultivated plots have organic matter contents of 1.02 %, and the forest (Quercus ilex sp.) plots reach the highest value: 14.98 %. Within those we found values that range from 2.34 %, in the recently abandoned plots (10 year abandonment), to values of 8.23 % in the 50 year old abandoned fields.The results demonstrate that there is a recovery of the organic carbon in abandoned soils and that the forest fires do no affect this trend. The increase of soil organic matter after abandonment is a result of the recovery of vegetation(Debussche et al., 2001), which is the consequence of the end of the disturbance of forest that have affected the Mediterranean for millennia (Barbero et al., 1990). The colonization of the

  15. Bicarbonate content of groundwater in carbonate rock in eastern North America

    USGS Publications Warehouse

    Trainer, F.W.; Heath, R.C.

    1976-01-01

    In carbonate-rock terrane the most effective solution occurs where soil and vegetative cover facilitate biogenic production and storage of CO2 in the soil until part of it is carried downward in percolating water. Bicarbonate data for groundwater in eastern North America are examined in the light of these conditions, of the CO2 content of soil gas, and of the timing of groundwater recharge relative to seasonal changes in soil temperature. There appears to be no well-marked relation between latitude and bicarbonate content of groundwater in this region. Interplay of all the factors listed above, and of lithology and soil types, is evidently such that under optimum conditions the amount of solution of carbonate rock is roughly comparable, per unit of groundwater recharge, over the region from Ohio to Florida (and, perhaps, to Puerto Rico and Yucatan). Relatively low HCO3 concentrations observed in much of the southern United States are attributed to low production and storage of CO2 in sandy soil that is poor in organic matter. On the other hand, concentrations observed in Ontario, New York and Michigan are markedly higher than is to be expected from interrelations of the factors considered. These high values, apparently anomalous, are attributed in part to solution of granular glacial drift derived largely from carbonate rock. ?? 1976.

  16. Carbon content of atmospheric aerosols in a residential area during the wood combustion season in Sweden

    NASA Astrophysics Data System (ADS)

    Krecl, Patricia; Ström, Johan; Johansson, Christer

    Carbonaceous aerosol particles were observed in a residential area with wood combustion during wintertime in Northern Sweden. Filter samples were analyzed for elemental carbon (EC) and organic carbon (OC) content by using a thermo-optical transmittance method. The light-absorbing carbon (LAC) content was determined by employing a commercial Aethalometer and a custom-built particle soot absorption photometer. Filter samples were used to convert the optical signals to LAC mass concentrations. Additional total PM 10 mass concentrations and meteorological parameters were measured. The mean and standard deviation mass concentrations were 4.4±3.6 μg m -3 for OC, and 1.4±1.2 μg m -3 for EC. On average, EC accounted for 10.7% of the total PM 10 and the contribution of OC to the total PM 10 was 35.4%. Aethalometer and custom-built PSAP measurements were highly correlated ( R2=0.92). The hourly mean value of LAC mass concentration was 1.76 μg m -3 (median 0.88 μg m -3) for the winter 2005-2006. This study shows that the custom-built PSAP is a reliable alternative for the commercial Aethalometer with the advantage of being a low-cost instrument.

  17. 60NiTi Alloy for Tribological and Biomedical Surface Engineering Applications

    NASA Astrophysics Data System (ADS)

    Ingole, Sudeep

    2013-06-01

    60NiTi is an alloy with 60 wt% of nickel (Ni) and 40 wt% of titanium (Ti). This alloy was developed in the 1950s at the Naval Ordnance Laboratory (NOL) along with 55NiTi (55 wt% of Ni and 45 wt% of Ti). Both of these alloys exhibit the shape memory effect to different extents. The unique properties of 60NiTi, which are suitable for surface engineering (tribological) applications, are enumerated here. With appropriate heat treatment, this alloy can achieve high hardness (between Rc 55 and Rc 63). It has very good corrosion resistance and is resilient. Machinable before its final heat treatment, this alloy can be ground to fine surface finish and to tight dimensions. At one time, due to the popularity and wider applications of 55NiTi, the study of 60NiTi suffered. Recently, 60NiTi alloy gained some technological advantages due to advanced materials synthesis processes and progress in surface engineering. A feasibility study of 60NiTi bearings for space application has shown promise for its further development and suitability for other tribological applications. This report focuses on an overview of the properties and potential tribological and biomedical applications of 60NiTi.

  18. NITI Needs Assessment Study. A Study of the Postsecondary Educational Needs of Merged Area I.

    ERIC Educational Resources Information Center

    Ratcliff, James L.

    The study described in this report was conducted to determine whether the present mix of vocational-technical and adult educational programs and services at Northeast Iowa Technical Institute (NITI) was optimal in meeting the needs of the constituents and clients of the college. Particular attention was given to the question of whether NITI would…

  19. Topsoil organic carbon content of Europe, a new map based on a generalised additive model

    NASA Astrophysics Data System (ADS)

    de Brogniez, Delphine; Ballabio, Cristiano; Stevens, Antoine; Jones, Robert J. A.; Montanarella, Luca; van Wesemael, Bas

    2014-05-01

    There is an increasing demand for up-to-date spatially continuous organic carbon (OC) data for global environment and climatic modeling. Whilst the current map of topsoil organic carbon content for Europe (Jones et al., 2005) was produced by applying expert-knowledge based pedo-transfer rules on large soil mapping units, the aim of this study was to replace it by applying digital soil mapping techniques on the first European harmonised geo-referenced topsoil (0-20 cm) database, which arises from the LUCAS (land use/cover area frame statistical survey) survey. A generalized additive model (GAM) was calibrated on 85% of the dataset (ca. 17 000 soil samples) and a backward stepwise approach selected slope, land cover, temperature, net primary productivity, latitude and longitude as environmental covariates (500 m resolution). The validation of the model (applied on 15% of the dataset), gave an R2 of 0.27. We observed that most organic soils were under-predicted by the model and that soils of Scandinavia were also poorly predicted. The model showed an RMSE of 42 g kg-1 for mineral soils and of 287 g kg-1 for organic soils. The map of predicted OC content showed the lowest values in Mediterranean countries and in croplands across Europe, whereas highest OC content were predicted in wetlands, woodlands and in mountainous areas. The map of standard error of the OC model predictions showed high values in northern latitudes, wetlands, moors and heathlands, whereas low uncertainty was mostly found in croplands. A comparison of our results with the map of Jones et al. (2005) showed a general agreement on the prediction of mineral soils' OC content, most probably because the models use some common covariates, namely land cover and temperature. Our model however failed to predict values of OC content greater than 200 g kg-1, which we explain by the imposed unimodal distribution of our model, whose mean is tilted towards the majority of soils, which are mineral. Finally, average

  20. Effect of Charcoal Volatile Matter Content and Feedstock on Soil Microbe-Carbon-Nitrogen Dynamics

    NASA Astrophysics Data System (ADS)

    McClellan, T.; Deenik, J. L.; Hockaday, W. C.; Campbell, S.; Antal, M. J., Jr.

    2010-12-01

    Charcoal has important biogeochemical implications in soil—first as a means to sequester carbon, and second as a soil conditioner to potentially enhance soil quality and fertility. Volatile matter (VM) content is a property of charcoal which describes its degree of thermal alteration, or carbonization. Results from greenhouse experiments have shown that plant growth can be negatively affected by charcoals with high VM content (20-35%), with and without fertilizer supplements, whereas low VM charcoal (6-9%) increased plant growth when combined with fertilizer. We conducted two laboratory studies to characterize the VM content of charcoals derived from two feedstocks (corncob and kiawe) and relate observed differences to key aspects of soil fertility. Using Fourier transform infrared spectroscopy (FTIR), 13C nuclear magnetic resonance (NMR), total phenol content (using a Prussian blue colorimetric assay), and gas chromatography-mass spectrometry (GC-MS), we found that the VM content of charcoal primarily consisted of alkanes, oxygen-substituted alkanes, and phenolic compounds. However, the GC-MS data indicated that charcoals can differ vastly in their extractable fraction, depending upon both VM content and feedstock. In a second set of experiments, we examined the effect of VM content and feedstock on soil microbial activity, available nitrogen (N), and soluble carbon (C). High VM corncob charcoals significantly enhanced microbial activity, coupled with net reduction in available N and soluble C. For a given feedstock, the extent of this effect was dependent upon VM content. However, the overall effect of VM content on microbial dynamics was apparently related to the composition of the acetone-extractable fraction, which was particularly important when comparing two charcoals derived from different feedstocks but with the equivalent VM contents. Removing the acetone-extractable fraction from the 23% VM corncob charcoal significantly reduced the enhancement of

  1. Investigation on the evolution of microstructure and texture of electroplated Ni-Ti composite coating by Rietveld method

    NASA Astrophysics Data System (ADS)

    Zhao, Yuantao; Cai, Fei; Wang, Chengxi; Chai, Ze; Zhu, Kaiyuan; Xu, Zhou; Jiang, Chuanhai

    2015-10-01

    Rietveld refinement was utilized to investigate the evolution of microstructure and texture of the Ni-Ti composite coatings electroplated at different applied current densities. Scanning Electron Microscope and Energy Dispersive Spectroscopy were utilized to investigate the morphology and chemical composition of the coatings. Relative texture coefficients (RTC) and measured pole figures were utilized to investigate the texture evolution of the coatings. The results showed that the surface morphology of the coatings changed from a colonial structure to a polyhedral one. And the incorporated Ti content decreased with increasing applied current density. As the applied current density increased, the crystallite sizes increased and their distribution got less uniform, and the microstrain and dislocation density decreased. The results of simulated pole figures obtained from Rietveld refinement illustrated that the texture of the coatings changed from no obvious texture to a strong [2 0 0] fiber texture with increasing applied current density. The texture evolution obtained from simulated pole figures was confirmed by the result of RTC and the measured pole figures. The evolutions of the microstructure and texture were derived from the change of the applied current density and incorporated Ti content in the Ni-Ti composite coatings.

  2. The carbon isotopes ratio and trace metals content determinations in some Transylvanian fruit juices

    NASA Astrophysics Data System (ADS)

    Dehelean, A.; Magdas, D. A.; Cristea, G.

    2012-02-01

    This work presents a preliminary study on the carbon isotope signature and trace metal content investigated on the soil-plant-fruit pulp chain. The samples were collected from two Transylvanian areas namely Alba and Salaj. The average value of the δ13C at the soil surface was around δ13C ≈ -27%° and important differences of the δ13C values between the two studied areas were not observed. Meanwhile, differences between fruit pulp of grape juice and the pulp of pear juice relived a difference of about 1.5%° for δ13C values.

  3. Determination of groundwater mercury (II) content using a disposable gold modified screen printed carbon electrode.

    PubMed

    Somé, Issa Touridomon; Sakira, Abdoul Karim; Mertens, Dominique; Ronkart, Sebastien N; Kauffmann, Jean-Michel

    2016-05-15

    Mercury (II) measurements were performed thanks to a newly developed electrochemical method using a disposable gold modified screen printed carbon electrode. The method has a wide dynamic range (1-100 µg/L), a good accuracy and a limit of detection in compliance with WHO standards. The application of the method to several groundwater samples made it possible to identify, for the first time, mercury content higher than the recommended WHO standard value in a gold mining activity area in the northern part of Burkina Faso. The accuracy of the assay was checked by ICP/MS. PMID:26992529

  4. Confident methods for the evaluation of the hydrogen content in nanoporous carbon microfibers

    PubMed Central

    2012-01-01

    Nanoporous carbon microfibers were grown by chemical vapor deposition in the vapor-liquid solid mode using different fluid hydrocarbons as precursors in different proportions. The as-grown samples were further treated in argon and hydrogen atmospheres at different pressure conditions and annealed at several temperatures in order to deduce the best conditions for the incorporation and re-incorporation of hydrogen into the microfibers through the nanopores. Since there are some discrepancies in the results on the hydrogen content obtained under vacuum conditions, in this work, we have measured the hydrogen content in the microfibers using several analytical methods in ambient conditions: surface tension, mass density, and Raman measurements. A discussion on the validity of the results obtained through the correlation between them is the purpose of the present work. PMID:23095321

  5. Enhanced endothelial cell density on NiTi surfaces with sub-micron to nanometer roughness

    PubMed Central

    Samaroo, Harry D; Lu, Jing; Webster, Thomas J

    2008-01-01

    The shape memory effect and superelastic properties of NiTi (or Nitinol, a nickel-titanium alloy) have already attracted much attention for various biomedical applications (such as vascular stents, orthodontic wires, orthopedic implants, etc). However, for vascular stents, conventional approaches have required coating NiTi with anti-thrombogenic or anti-inflammatory drug-eluting polymers which as of late have proven problematic for healing atherosclerotic blood vessels. Instead of focusing on the use of drug-eluting anti-thrombogenic or anti-inflammatory proteins, this study focused on promoting the formation of a natural anti-thrombogenic and anti-inflammatory surface on metallic stents: the endothelium. In this study, we synthesized various NiTi substrates with different micron to nanometer surface roughness by using dissimilar dimensions of constituent NiTi powder. Endothelial cell adhesion on these compacts was compared with conventional commercially pure (cp) titanium (Ti) samples. The results after 5 hrs showed that endothelial cells adhered much better on fine grain (<60 μm) compared with coarse grain NiTi compacts (<100 μm). Coarse grain NiTi compacts and conventional Ti promoted similar levels of endothelial cell adhesion. In addition, cells proliferated more after 5 days on NiTi with greater sub-micron and nanoscale surface roughness compared with coarse grain NiTi. In this manner, this study emphasized the positive pole that NiTi with sub-micron to nanometer surface features can play in promoting a natural anti-thrombogenic and anti-inflammatory surface (the endothelium) on a vascular stent and, thus, suggests that more studies should be conducted on NiTi with sub-micron to nanometer surface features. PMID:18488418

  6. CVD growth of carbon nanotubes on thin-film Ni20Ti35N45 alloy catalyst

    NASA Astrophysics Data System (ADS)

    Gromov, D. G.; Pavlov, A. A.; Skorik, S. N.; Trifonov, A. Yu.; Shulyat'ev, A. S.

    2015-12-01

    The possibility of forming carbon nanotube (CNT) arrays on a Ni-Ti-N catalytic alloy with low nickel content by chemical vapor deposition (CVD) is demonstrated. Adding nitrogen to the Ni-Ti alloy composition favors the formation of TiN compound and segregation of Ni on the surface, where it produces a catalytic effect on the CNT growth. It is found that, using CVD from acetylene gas phase at a substrate temperature of 650°C, a CNT array of 9-µm height can be grown for 2 min.

  7. Multidimensional fluorescence studies of the phenolic content of dissolved organic carbon in humic substances.

    PubMed

    Pagano, Todd; Ross, Annemarie D; Chiarelli, Joseph; Kenny, Jonathan E

    2012-03-01

    Indicators suggest that the amount of dissolved organic carbon (DOC) in natural waters may be increasing. Climate change has been proposed as a potential contributor to the trend, and under such a mechanism, the phenolic content of DOC may also be increasing. This study explores the assessment of the phenolic character of DOC using multidimensional fluorescence spectroscopy as a more convenient alternative to traditional wet chemistry methods. Parallel factor analysis (PARAFAC) is applied to fluorescence excitation emission matrices (EEMs) of humic samples to analyze inherent phenolic content. The PARAFAC results are correlated with phenol concentrations derived from the Folin-Ciocalteau reagent-based method. The reagent-based method reveals that the phenolic content of five International Humic Substance Society (IHSS) samples varies from approximately 5.2 to 22 ppm Tannic Acid Equivalents (TAE). A four-component PARAFAC fit is applied to the EEMs of the IHSS sample dataset and it is determined by PARAFAC score correlations with phenol concentrations from the reagent-based method that components C2, C3, and C4 have the highest probability of containing phenolic groups. The results show the potential for PARAFAC analysis of multidimensional fluorescence data for monitoring the phenolic content of DOC.

  8. Soil Iron Content as a Predictor of Carbon and Nutrient Mobilization in Rewetted Fens

    PubMed Central

    Emsens, Willem-Jan; Aggenbach, Camiel J. S.; Schoutens, Ken; Smolders, Alfons J. P.; Zak, Dominik; van Diggelen, Rudy

    2016-01-01

    Rewetted, previously drained fens often remain sources rather than sinks for carbon and nutrients. To date, it is poorly understood which soil characteristics stimulate carbon and nutrient mobilization upon rewetting. Here, we assess the hypothesis that a large pool of iron in the soil negatively affects fen restoration success, as flooding-induced iron reduction (Fe3+ to Fe2+) causes a disproportionate breakdown of organic matter that is coupled with a release of inorganic compounds. We collected intact soil cores in two iron-poor and two iron-rich drained fens, half of which were subjected to a rewetting treatment while the other half was kept drained. Prolonged drainage led to the mobilization of nitrate (NO3-, > 1 mmol L-1) in all cores, regardless of soil iron content. In the rewetted iron-rich cores, a sharp increase in pore water iron (Fe) concentrations correlated with concentrations of inorganic carbon (TIC, > 13 mmol L-1) and dissolved organic carbon (DOC, > 16 mmol L-1). Additionally, ammonium (NH4+) accumulated up to phytotoxic concentrations of 1 mmol L-1 in the pore water of the rewetted iron-rich cores. Disproportionate mobilization of Fe, TIC, DOC and NH4+ was absent in the rewetted iron-poor cores, indicating a strong interaction between waterlogging and iron-mediated breakdown of organic matter. Concentrations of dissolved phosphorus (P) rose slightly in all cores upon rewetting, but remained low throughout the experiment. Our results suggest that large pools of iron in the top soil of drained fens can hamper the restoration of the fen’s sink-service for ammonium and carbon upon rewetting. We argue that negative effects of iron should be most apparent in fens with fluctuating water levels, as temporary oxygenation allows frequent regeneration of Fe3+. We conclude that rewetting of iron-poor fens may be more feasible for restoration. PMID:27050837

  9. Soil Iron Content as a Predictor of Carbon and Nutrient Mobilization in Rewetted Fens.

    PubMed

    Emsens, Willem-Jan; Aggenbach, Camiel J S; Schoutens, Ken; Smolders, Alfons J P; Zak, Dominik; van Diggelen, Rudy

    2016-01-01

    Rewetted, previously drained fens often remain sources rather than sinks for carbon and nutrients. To date, it is poorly understood which soil characteristics stimulate carbon and nutrient mobilization upon rewetting. Here, we assess the hypothesis that a large pool of iron in the soil negatively affects fen restoration success, as flooding-induced iron reduction (Fe3+ to Fe2+) causes a disproportionate breakdown of organic matter that is coupled with a release of inorganic compounds. We collected intact soil cores in two iron-poor and two iron-rich drained fens, half of which were subjected to a rewetting treatment while the other half was kept drained. Prolonged drainage led to the mobilization of nitrate (NO3-, > 1 mmol L-1) in all cores, regardless of soil iron content. In the rewetted iron-rich cores, a sharp increase in pore water iron (Fe) concentrations correlated with concentrations of inorganic carbon (TIC, > 13 mmol L-1) and dissolved organic carbon (DOC, > 16 mmol L-1). Additionally, ammonium (NH4+) accumulated up to phytotoxic concentrations of 1 mmol L-1 in the pore water of the rewetted iron-rich cores. Disproportionate mobilization of Fe, TIC, DOC and NH4+ was absent in the rewetted iron-poor cores, indicating a strong interaction between waterlogging and iron-mediated breakdown of organic matter. Concentrations of dissolved phosphorus (P) rose slightly in all cores upon rewetting, but remained low throughout the experiment. Our results suggest that large pools of iron in the top soil of drained fens can hamper the restoration of the fen's sink-service for ammonium and carbon upon rewetting. We argue that negative effects of iron should be most apparent in fens with fluctuating water levels, as temporary oxygenation allows frequent regeneration of Fe3+. We conclude that rewetting of iron-poor fens may be more feasible for restoration.

  10. Soil Iron Content as a Predictor of Carbon and Nutrient Mobilization in Rewetted Fens.

    PubMed

    Emsens, Willem-Jan; Aggenbach, Camiel J S; Schoutens, Ken; Smolders, Alfons J P; Zak, Dominik; van Diggelen, Rudy

    2016-01-01

    Rewetted, previously drained fens often remain sources rather than sinks for carbon and nutrients. To date, it is poorly understood which soil characteristics stimulate carbon and nutrient mobilization upon rewetting. Here, we assess the hypothesis that a large pool of iron in the soil negatively affects fen restoration success, as flooding-induced iron reduction (Fe3+ to Fe2+) causes a disproportionate breakdown of organic matter that is coupled with a release of inorganic compounds. We collected intact soil cores in two iron-poor and two iron-rich drained fens, half of which were subjected to a rewetting treatment while the other half was kept drained. Prolonged drainage led to the mobilization of nitrate (NO3-, > 1 mmol L-1) in all cores, regardless of soil iron content. In the rewetted iron-rich cores, a sharp increase in pore water iron (Fe) concentrations correlated with concentrations of inorganic carbon (TIC, > 13 mmol L-1) and dissolved organic carbon (DOC, > 16 mmol L-1). Additionally, ammonium (NH4+) accumulated up to phytotoxic concentrations of 1 mmol L-1 in the pore water of the rewetted iron-rich cores. Disproportionate mobilization of Fe, TIC, DOC and NH4+ was absent in the rewetted iron-poor cores, indicating a strong interaction between waterlogging and iron-mediated breakdown of organic matter. Concentrations of dissolved phosphorus (P) rose slightly in all cores upon rewetting, but remained low throughout the experiment. Our results suggest that large pools of iron in the top soil of drained fens can hamper the restoration of the fen's sink-service for ammonium and carbon upon rewetting. We argue that negative effects of iron should be most apparent in fens with fluctuating water levels, as temporary oxygenation allows frequent regeneration of Fe3+. We conclude that rewetting of iron-poor fens may be more feasible for restoration. PMID:27050837

  11. Mapping soil organic carbon content and composition across Australia to assess vulnerability to climate change

    NASA Astrophysics Data System (ADS)

    Viscarra Rossel, R. A.

    2015-12-01

    We can effectively monitor soil condition—and develop sound policies to offset the emissions of greenhouse gases—only with accurate data from which to define baselines. Currently, estimates of soil organic C for countries or continents are either unavailable or largely uncertain because they are derived from sparse data, with large gaps over many areas of the Earth. Here, we derive spatially explicit estimates, and their uncertainty, of the distribution and stock of organic C content and composition in the soil of Australia. The composition of soil organic C may be characterized by chemical separation or physical fractionation based on either particle size or particle density (Skjemstad et al., 2004; Gregorich et al., 2006; Kelleher&Simpson, 2006; Zimmermann et al., 2007). In Australia, for example, Skjemstad et al. (2004) used physical separation of soil samples into 50-2000 and <50-μm particle-size fractions followed by the measurement of char-carbon using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, giving the three OC pools, particulate organic carbon (POC), humic organic carbon (HOC) and resistant organic carbon (ROC; charcoal or char-carbon). We assembled and harmonized data from several sources to produce the most comprehensive set of data on the current stock of organic C in soil of the continent. Using them, we have produced a fine spatial resolution baseline map of organic C, POC, HOC and ROC at the continental scale. In this presentation I will describe how we made the maps and how we use them to assess the vulnerability of soil organic C to for instance climate change.

  12. Structure and Crystallization Behavior of Nylong 66/Multi-Walled Carbon Nanotube Nanocomposites at Low Carbon Nanotube Contents

    SciTech Connect

    Li,L.; Li, C.; Ni, C.; Rong, L.; Hsiao, B.

    2007-01-01

    Multi-walled carbon nanotubes (MWNTs) were modified with poly(hexamethylene adipamide) (also known as Nylon 66) via a controlled polymer solution crystallization method. A 'nanohybrid shish kebab' (NHSK) structure was found wherein the MWNT resembled the shish while Nylon 66 lamellar crystals formed the kebabs. These Nylon 66-functionalized MWNTs were used as precursors to prepare polymer/MWNT nanocomposites. Excellent dispersion was revealed by optical and electron microscopies. Nitric acid etching of the nanocomposites showed that MWNT formed a robust network in Nylon 66. Non-isothermal DSC results showed multiple melting peaks, which can be attributed to lamellar thickness changes upon heating. The crystallite sizes L{sub 100} and L{sup 010} of Nylon 66, determined by WAXD, decreased with increasing MWNT contents. Isothermal DSC results showed that crystallization kinetics increased first and then decreased with increasing MWNT contents in Nylon 66. This study showed that the effect of MWNTs on Nylon 66 crystallization is twofold: MWNTs provide heterogeneous nucleation sites for Nylon 66 crystallization while the tube network structure hinders large crystal growth.

  13. Innovative materials: the NiTi alloys in orthodontics.

    PubMed

    Airoldi, G; Riva, G

    1996-01-01

    Since ten years the NiTi alloys have gained an ever increasing place in orthodontic practice: that is due to their peculiar mechanical properties ascribed to a martensitic thermoelastic transformation which can be thermally or, in a proper temperature range, stress-induced. In the last case, when martensite is stress-induced at body temperature, the stress-strain behaviour is pseudoelastic with large deformations gained or recovered at constant stress, respectively in direct/reverse transformation: this behaviour exploited in orthodontics allowed to overcome the drawbacks intrinsic to the use of conventional alloys as stainless steel or Co-Mo alloys, where small displacements can be achieved at decreasing loads. From the phase state diagram of NiTi alloys it appears that at body temperature they are stable, but out of equilibrium: thermal treatments at intermediate temperatures can therefore modify the equilibrium state and as a consequence the transformation temperatures respect to body temperature. That allows to modify the recovery stress level according to the requirements of practice and thus disclosing new roads: the capability to foresee NiTi archwires pre-programmed in different sections, with a personalized scheme. Attention has not currently been paid to the modifications in the recovery stress induced by a temperature change inside the oral cavity. Recent results have shown that the thermal changes in the oral cavity induced by cold/hot liquid intake can considerably modify the stress level to which the dentition is exposed: though confined to the time extent connected with drinking, similar effects can be expected also for meals intake and should be taken into account for a correct procedure.

  14. Effect of chloride content of molten nitrate salt on corrosion of A516 carbon steel.

    SciTech Connect

    Bradshaw, Robert W.; Clift, W. Miles

    2010-11-01

    The corrosion behavior of A516 carbon steel was evaluated to determine the effect of the dissolved chloride content in molten binary Solar Salt. Corrosion tests were conducted in a molten salt consisting of a 60-40 weight ratio of NaNO{sub 3} and KNO{sub 3} at 400{sup o}C and 450{sup o}C for up to 800 hours. Chloride concentrations of 0, 0.5 and 1.0 wt.% were investigated to determine the effect on corrosion of this impurity, which can be present in comparable amounts in commercial grades of the constituent salts. Corrosion rates were determined by descaled weight losses, corrosion morphology was examined by metallographic sectioning, and the types of corrosion products were determined by x-ray diffraction. Corrosion proceeded by uniform surface scaling and no pitting or intergranular corrosion was observed. Corrosion rates increased significantly as the concentration of dissolved chloride in the molten salt increased. The adherence of surface scales, and thus their protective properties, was degraded by dissolved chloride, fostering more rapid corrosion. Magnetite was the only corrosion product formed on the carbon steel specimens, regardless of chloride content or temperature.

  15. Stable atomic structure of NiTi austenite

    SciTech Connect

    Zarkevich, Nikolai A; Johnson, Duane D

    2014-08-01

    Nitinol (NiTi), the most widely used shape-memory alloy, exhibits an austenite phase that has yet to be identified. The usually assumed austenitic structure is cubic B2, which has imaginary phonon modes, hence it is unstable. We suggest a stable austenitic structure that “on average” has B2 symmetry (observed by x-ray and neutron diffraction), but it exhibits finite atomic displacements from the ideal B2 sites. The proposed structure has a phonon spectrum that agrees with that from neutron scattering, has diffraction spectra in agreement with x-ray diffraction, and has an energy relative to the ground state that agrees with calorimetry data.

  16. [Soil organic carbon content and its distribution pattern in Hangzhou Bay coastal wetlands].

    PubMed

    Shao, Xue-xin; Yang, Wen-ying; Wu, Ming; Jiang, Ke-yi

    2011-03-01

    In this paper, the soil organic carbon (SOC) content and its distribution pattern in the natural intertidal zones and reclaimed wetlands of Hangzhou Bay were studied, aimed to explore the effects of vegetation succession, exotic species invasion, and reclamation on the SOC in costal wetlands of the Bay. In intertidal zones, the surface SOC content ranged from 4.41 to 8.58 g x kg(-1), with an average of 6.45 g x kg(-1), and differed significantly under different vegetations, with a tendency of under Phragmites australis (8.56 +/- 0.04 g x kg(-1)) > Spartina alterniflora (7.31 +/- 0.08 g x kg(-1)) > Scirpus mariqueter (5.48 +/- 0.29 g x kg(-1)) > mudflats (4.47 +/- 0.09 g x kg(-1)); in reclaimed wetlands, the surface SOC content was 7.46 +/- 0.25 g x kg(-1) in the 1960s, 1.96 +/- 0.46 g x kg(-1) in the 1980s, and 5.12 +/- 0.16 g x kg(-1) in 2003, showing a trend of increased after an initial decrease with increasing reclamation year. The SOC in the profiles all showed a decreasing trend from the surface to the bottom. The SOC in intertidal zones and reclaimed wetlands was significantly negatively correlated with soil pH, and positively correlated with soil total nitrogen (TN), suggesting a large reserve of organic nitrogen in TN. The correlation between SOC and soil C/N ratio was not obvious in intertidal zones, but significantly positive in reclaimed wetlands, indicating that reclamation affected soil C/N ratio to a certain extent. This study showed that in the intertidal zones, soil carbon sequestration capacity increased gradually with plant community succession. However, the invasion of exotic species Spartina alternflora might decrease the capacity of carbon sequestration in intertidal zones. It was also found that the changes of soil moisture content, particle composition, vegetation coverage, and reclamation history were the main factors affecting the SOC distribution in reclaimed wetlands.

  17. Effect of carbon content on the microstructure and mechanical properties of superfine Ti(C, N)-based cermets

    SciTech Connect

    Liu Ning Liu Xuesong; Zhang Xiaobo; Zhu Longwei

    2008-10-15

    As a new kind of tool materials which appeared in the seventies last century, the Ti (C, N)-based cermets have been widely used in recent years due to many of its good properties. The microstructure of Ti(C, N)-based cermets with various carbon content were studied using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). Vickers hardness and transverse rupture strength (TRS) were also measured. An increased carbon content resulted in the finer grain size, decreased solution strength of tungsten and molybdenum in the binder phase, and a higher volume fraction of heavy (Ti, Mo, W)(C,N) cores. If the addition of carbon content is too little or too much, the phase composition of material will deviate from the normal dual phase section and lead to the formation of the third phase: {eta}-phase if the carbon content is too low or dissociative carbon if the carbon content is too high. And the formation of the third phase will remarkably deteriorate the mechanical properties of cermets.

  18. Diel changes in the near-surface biomass of zooplankton and the carbon content of vertical migrants

    NASA Astrophysics Data System (ADS)

    Hays, Graeme C.; Harris, Roger P.; Head, Robert N.

    Zooplankton biomass and the carbon content of vertical migrants were measured in the NE Atlantic (36.5°N, 19.2°W) between 11 and 18 July 1996 as part of the Plankton Reactivity in the Marine Environment (PRIME) programme. The increase in zooplankton biomass near the surface (0-100 m) at night compared to during the day suggested that diel vertical migration was an important feature at this site. For three species of vertically migrant copepods, Pleuromamma pisekii, P. gracilis and P. abdominalis, the carbon content of individuals collected at dusk was significantly less than for individuals collected at dawn, with this reduction being 6.2, 7.3 and 14.8%, respectively. This dawn-dusk reduction in carbon content is consistent with the diel pattern of feeding and fasting exhibited by vertical migrants and supports the suggestion that migrating zooplankton will cause an active export of carbon from the surface layers.

  19. Pheophytinase Knockdown Impacts Carbon Metabolism and Nutraceutical Content Under Normal Growth Conditions in Tomato.

    PubMed

    Lira, Bruno Silvestre; Rosado, Daniele; Almeida, Juliana; de Souza, Amanda Pereira; Buckeridge, Marcos Silveira; Purgatto, Eduardo; Guyer, Luzia; Hörtensteiner, Stefan; Freschi, Luciano; Rossi, Magdalena

    2016-03-01

    Although chlorophyll (Chl) degradation is an essential biochemical pathway for plant physiology, our knowledge regarding this process still has unfilled gaps. Pheophytinase (PPH) was shown to be essential for Chl breakdown in dark-induced senescent leaves. However, the catalyzing enzymes involved in pigment turnover and fruit ripening-associated degreening are still controversial. Chl metabolism is closely linked to the biosynthesis of other isoprenoid-derived compounds, such as carotenoids and tocopherols, which are also components of the photosynthetic machinery. Chls, carotenoids and tocopherols share a common precursor, geranylgeranyl diphosphate, produced by the plastidial methylerythritol 4-phosphate (MEP) pathway. Additionally, the Chl degradation-derived phytol can be incorporated into tocopherol biosynthesis. In this context, tomato turns out to be an interesting model to address isoprenoid-metabolic cross-talk since fruit ripening combines degreening and an intensely active MEP leading to carotenoid accumulation. Here, we investigate the impact of PPH deficiency beyond senescence by the comprehensive phenotyping of SlPPH-knockdown tomato plants. In leaves, photosynthetic parameters indicate altered energy usage of excited Chl. As a mitigatory effect, photosynthesis-associated carotenoids increased while tocopherol content remained constant. Additionally, starch and soluble sugar profiles revealed a distinct pattern of carbon allocation in leaves that suggests enhanced sucrose exportation. The higher levels of carbohydrates in sink organs down-regulated carotenoid biosynthesis. Additionally, the reduction in Chl-derived phytol recycling resulted in decreased tocopherol content in transgenic ripe fruits. Summing up, tocopherol and carotenoid metabolism, together with the antioxidant capacity of the hydrophilic and hydrophobic fractions, were differentially affected in leaves and fruits of the transgenic plants. Thus, in tomato, PPH plays a role beyond

  20. A Comparison of Chemistry and Inclusion Distribution and Morphology Versus Melting Method of NiTi Alloys

    NASA Astrophysics Data System (ADS)

    Kramer, George M.

    2009-08-01

    NiTi alloys are produced by three melting methods. The first method requires compaction of nickel and titanium raw material into sections that can be joined together for melting in a Vacuum Arc Remelt unit (VAR). This ingot is melted two or more times in a VAR. The second method utilizes a Vacuum Induction Melting (VIM) unit to alloy the nickel and titanium, with the use of a graphite crucible. The resulting ingot is prepared and remelted in a VAR. The third method begins with primary melting in a vacuum Induction Skull Melter (ISM). The ISM produces ingots that are assembled into an electrode for VAR melting. For each of the melting methods, the final product depends on the quality and handling of the raw materials, the control of the process at each unit, and the preparation of the intermediate ingots for further processing. The melting method influences the final chemistry as well as the type and number of inclusions present in the final product. This study compares the chemistry and microcleanliness of product manufactured by each method to determine the appropriate melting technique that produces NiTi with the lowest residual elements, such as carbon, as well as the lowest size, and number of inclusions.

  1. Microstructural Characterization of Diffusion Bonds Assisted by Ni/Ti Nanolayers

    NASA Astrophysics Data System (ADS)

    Simões, Sónia; Viana, Filomena; Sofia Ramos, A.; Teresa Vieira, M.; Vieira, Manuel F.

    2016-08-01

    The microstructure of similar and dissimilar diffusion bonds of metallic materials using reactive Ni/Ti interlayers was studied in this investigation. The base material surfaces were modified by sputter deposition of alternated Ni and Ti nanolayers. These nanolayers increase the diffusivity at the interface, enhancing the bonding process. Bonding experiments were performed at 800 °C under a pressure of 10 MPa with a bonding time of 60 min. The reaction zone was characterized by high-resolution scanning and transmission electron microscopies. Microstructural characterization reveals that similar (NiTi to NiTi and TiAl to TiAl) and dissimilar (NiTi to Ti6Al4V and TiAl to stainless steel) joints can be obtained successfully with Ni/Ti reactive nanolayers. The interfaces are thin (<10 µm) and their microstructure (thickness and number of zones, size and shape of the grains) depends on the elements diffusing from the base materials. For all joints, the interface is mainly composed of equiaxed grains of NiTi and NiTi2.

  2. Fabrication of porous NiTi shape memory alloy structures using laser engineered net shaping.

    PubMed

    Krishna, B Vamsi; Bose, Susmita; Bandyopadhyay, Amit

    2009-05-01

    Porous NiTi alloy samples were fabricated with 12-36% porosity from equiatomic NiTi alloy powder using laser engineered net shaping (LENS). The effects of processing parameters on density and properties of laser-processed NiTi alloy samples were investigated. It was found that the density increased rapidly with increasing the specific energy input up to 50 J/mm(3). Further increase in the energy input had small effect on density. High cooling rates associated with LENS processing resulted in higher amount of cubic B2 phase, and increased the reverse transformation temperatures of porous NiTi samples due to thermally induced stresses and defects. Transformation temperatures were found to be independent of pore volume, though higher pore volume in the samples decreased the maximum recoverable strain from 6% to 4%. Porous NiTi alloy samples with 12-36% porosity exhibited low Young's modulus between 2 and 18 GPa as well as high compressive strength and recoverable strain. Because of high open pore volume between 36% and 62% of total volume fraction porosity, these porous NiTi alloy samples can potentially accelerate the healing process and improve biological fixation when implanted in vivo. Thus porous NiTi is a promising biomaterial for hard tissue replacements.

  3. Launch Load Resistant Spacecraft Mechanism Bearings Made From NiTi Superelastic Intermetallic Materials

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Moore, Lewis E.

    2014-01-01

    Compared to conventional bearing materials (tool steel and ceramics), emerging Superelastic Intermetallic Materials (SIMs), such as 60NiTi, have significantly lower elastic modulus and enhanced strain capability. They are also immune to atmospheric corrosion (rusting). This offers the potential for increased resilience and superior ability to withstand static indentation load without damage. In this paper, the static load capacity of hardened 60NiTi 50mm bore ball-bearing races are measured to correlate existing flat-plate indentation load capacity data to an actual bearing geometry through the Hertz stress relations. The results confirmed the validity of using the Hertz stress relations to model 60NiTi contacts; 60NiTi exhibits a static stress capability (3.1GPa) between that of 440C (2.4GPa) and REX20 (3.8GPa) tool steel. When the reduced modulus and extended strain capability are taken into account, 60NiTi is shown to withstand higher loads than other bearing materials. To quantify this effect, a notional space mechanism, a 5kg mass reaction wheel, was modeled with respect to launch load capability when supported on 440C, 60NiTi and REX20 tool steel bearings. For this application, the use of REX20 bearings increased the static load capability of the mechanism by a factor of three while the use of 60NiTi bearings resulted in an order of magnitude improvement compared to the baseline 440C stainless steel bearings.

  4. Effect of variation in argon content of calibration gases on determination of atmospheric carbon dioxide.

    PubMed

    Min, Deullae; Kang, Namgoo; Moon, Dong Min; Lee, Jin Bok; Lee, Dong Soo; Kim, Jin Seog

    2009-12-15

    Carbon dioxide (CO(2)) is a greenhouse gas that makes by far the largest contribution to the global warming of the Earth's atmosphere. For the measurements of atmospheric CO(2) a non-dispersive infrared analyzer (NDIR) and gas chromatography are conventionally being used. We explored whether and to what degree argon content can influence the determination of atmospheric CO(2) using the comparison of CO(2) concentrations between the sample gas mixtures with varying Ar amounts at 0 and 18.6 mmol mol(-1) and the calibration gas mixtures with Ar at 8.4, 9.1, and 9.3 mmol mol(-1). We newly discovered that variation of Ar content in calibration gas mixtures could undermine accuracy for precise and accurate determination of atmospheric CO(2) in background air. The differences in CO(2) concentration due to the variation of Ar content in the calibration gas mixtures were negligible (<+/-0.03 micromol mol(-1)) for NDIR systems whereas they noticeably increased (<+/-1.09 micromol mol(-1)) especially for the modified GC systems to enhance instrumental sensitivity. We found that the thermal mass flow controller is the main source of the differences although such differences appeared only in the presence of a flow restrictor in GC systems. For reliable monitoring of real atmospheric CO(2) samples, one should use calibration gas mixtures that contain Ar content close to the level (9.332 mmol mol(-1)) in the ambient air as possible. Practical guidelines were highlighted relating to selection of appropriate analytical approaches for the accurate and precise measurements of atmospheric CO(2). In addition, theoretical implications from the findings were addressed.

  5. A Review of the Various Surface Treatments of NiTi Instruments

    PubMed Central

    Mohammadi, Zahed; Soltani, Mohammad Karim; Shalavi, Sousan; Asgary, Saeed

    2014-01-01

    Since the introduction of engine-driven nickel-titanium (NiTi) instruments, attempts have been made to minimize or eliminate their inherent defects, increase their surface hardness/flexibility and also improve their resistance to cyclic fatigue and cutting efficiency. The various strategies of enhancing instrument surface include ion implantation, thermal nitridation, cryogenic treatment and electropolishing. The purpose of this paper was to review the metallurgy and crystal characteristics of NiTi alloy and to present a general over review of the published articles on surface treatment of NiTi endodontic instruments. PMID:25386201

  6. Influence of Carbon Content on Fatigue Strength of Drawn Steel Tubes for Small Once-Through Boiler

    NASA Astrophysics Data System (ADS)

    Yonekura, Daisuke; Fujie, Yuta; Murakami, Ri-Ichi; Tokunaga, Yukihiro

    Tension-tension fatigue tests were performed to examine the influence of carbon content on the fatigue properties of drawn specific steel tube (STB340) with/without post heat treatment for small once-through boiler. Two different carbon content steel tubes, C=0.06 and 0.12% were prepared. The as-received, as-drawn and post drawing heat treated series for each carbon content tube were prepared for fatigue test. The hardness, grain size and residual stress were measured for each series. As a result, the fatigue strength of as-received and as-drawn series showed a small difference between C=0.06 and 0.12% specimens. However, the post drawing heat treatment series showed obvious difference in the fatigue strength. The fatigue strength of higher carbon content tubes significantly decreased by the post drawing heat treatment, whereas the decrease of fatigue strength was little for lower carbon content heat treated tubes. The difference of fatigue strength was mainly caused by the degree of relaxation of work hardening by post heat treatment.

  7. Structure Evolution of Ordered Mesoporous Carbons Induced by Water Content of Mixed Solvents Water/Ethanol.

    PubMed

    Li, Peng; Liang, Shujun; Li, Zhenzhong; Zhai, Yan; Song, Yan

    2016-12-01

    In this work, mesostructure evolution of ordered mesoporous carbons (OMCs) from the 2-D hexagonal (space group p6mm) to the discontinuous cubic [Formula: see text], then towards the face-centered cubic lattice [Formula: see text], and finally, to the simple cubic Pm3n is achieved by simply adjusting the cosolvent water content of the mixed solvents water/ethanol in the presence of a reverse nonionic triblock copolymer and low molecular resin by evaporation-induced self-assembly method. Experimental results demonstrate that both the cosolvent and the reverse triblock copolymer play a key role in the mesophase transitions of OMCs. Furthermore, the OMCs with Pm3n symmetry are reported for the first time. Finally, the mechanism of mesostructure transition was discussed and proposed. PMID:27518232

  8. Structure Evolution of Ordered Mesoporous Carbons Induced by Water Content of Mixed Solvents Water/Ethanol

    NASA Astrophysics Data System (ADS)

    Li, Peng; Liang, Shujun; Li, Zhenzhong; Zhai, Yan; Song, Yan

    2016-08-01

    In this work, mesostructure evolution of ordered mesoporous carbons (OMCs) from the 2-D hexagonal (space group p6mm) to the discontinuous cubic Fdoverline{3}m , then towards the face-centered cubic lattice Fmoverline{3}m , and finally, to the simple cubic Pm3n is achieved by simply adjusting the cosolvent water content of the mixed solvents water/ethanol in the presence of a reverse nonionic triblock copolymer and low molecular resin by evaporation-induced self-assembly method. Experimental results demonstrate that both the cosolvent and the reverse triblock copolymer play a key role in the mesophase transitions of OMCs. Furthermore, the OMCs with Pm3n symmetry are reported for the first time. Finally, the mechanism of mesostructure transition was discussed and proposed.

  9. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    NASA Astrophysics Data System (ADS)

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-06-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg-1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg-1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

  10. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    PubMed

    Yang, X M; Drury, C F; Reynolds, W D; Yang, J Y

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg(-1) soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg(-1), but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

  11. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    PubMed Central

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2–53 μm) and sand (53–2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg−1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg−1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation. PMID:27251365

  12. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    PubMed

    Yang, X M; Drury, C F; Reynolds, W D; Yang, J Y

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg(-1) soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg(-1), but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation. PMID:27251365

  13. The Impact of Buried Horizons and Deep Soil Pedogenesis on Soil Carbon Content and Vertical Distribution

    NASA Astrophysics Data System (ADS)

    James, J. N.; Dietzen, C.; Harrison, R. B.; Gross, C.; Kirpach, A.

    2015-12-01

    The lower boundary of soil has been a point of contention among soil scientists for decades. Recent evidence suggests that soil is much deeper than is measured by many ecological studies and that arbitrary definitions of maximum soil depth unnecessarily exclude important regions of the soil profile. This paper provides illustrated examples of soil profiles that have important deep soil characteristics or buried horizons. Soil pits were excavated with a backhoe to at least 2.5 m depth at 35 sites throughout the Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) ecoregion of the Pacific Northwest. These soils cover four orders - Andisol, Inceptisol, Alfisol, and Ultisol - and highlight the hidden diversity of subsoil characteristics throughout the region. The roots of trees and understory species often extended deep into the C horizons of soil. Despite experiencing less pedogenic development than surface horizons, C horizons are important as the frontier of soil formation, as an important resource for plant growth, and as a repository of diffuse but significant carbon storage. On average, there was 188.1 Mg C ha-1 total across all 35 sites, of which 76.3 Mg ha-1 (40.5%) was found below 0.5 m and 44.4 Mg ha-1 (23.6%) was found below 1 m. There was substantial variability in the vertical distribution of C with as little as 8.0% and as much as 58.0% of total C below 1 m. In some cases, B horizons are far deeper than the 1 or 2 m depth arbitrarily assumed to represent the whole soil. In other cases, subsoil hides buried profiles that can significantly impact total soil carbon stocks as well as aboveground plant growth. These buried horizons are important repositories of nutrients and carbon that are poorly understood and rarely sampled. Ignoring subsoil precludes incorporating soil burial or deep soil processes into biogeochemical and global carbon cycle models, and limits mechanistic understanding of carbon sequestration and mobilization in soil.

  14. Carboxylated molecules regulate magnesium content of amorphous calcium carbonates during calcification

    PubMed Central

    Wang, Dongbo; Wallace, Adam F.; De Yoreo, James J.; Dove, Patricia M.

    2009-01-01

    With the realization that many calcified skeletons form by processes involving a precursor phase of amorphous calcium carbonate (ACC), a new paradigm for mineralization is emerging. There is evidence the Mg content in biogenic ACC is regulated by carboxylated (acidic) proteins and other macromolecules, but the physical basis for such a process is unknown. We test the hypothesis that ACC compositions express a systematic relationship to the chemistry of carboxyl-rich biomolecules. A series of inorganic control experiments were conducted to establish the dependence of Mg/Ca ratios in ACC on solution composition. We then determined the influence of a suite of simple carboxylated organic acids on Mg content. Molecules with a strong affinity for binding Ca compared with Mg promote the formation of Mg-enriched ACC that is compositionally equivalent to high-magnesium calcites and dolomite. Measurements show Mg/Ca ratios are controlled by a predictable dependence upon the binding properties of the organic molecules. The trend appears rooted in the conformation and electrostatic potential topology of each molecule, but dynamic factors also may be involved. The dependence suggests a physical basis for reports that specific sequences of calcifying proteins are critical to modulating mineralization. Insights from this study may provide a plausible explanation for why some biogenic carbonates and carbonaceous cements often contain higher Mg signatures than those that are possible by classical crystal growth processes. The findings reiterate the controls of microenvironment on mineralization and suggest an origin of compositional offsets, or vital effects, long recognized by the paleoclimate community. PMID:19955417

  15. Urban stormwater runoff drives denitrifying community composition through changes in sediment texture and carbon content.

    PubMed

    Perryman, Shane E; Rees, Gavin N; Walsh, Christopher J; Grace, Michael R

    2011-05-01

    The export of nitrogen from urban catchments is a global problem, and denitrifying bacteria in stream ecosystems are critical for reducing in-stream N. However, the environmental factors that control the composition of denitrifying communities in streams are not well understood. We determined whether denitrifying community composition in sediments of nine streams on the eastern fringe of Melbourne, Australia was correlated with two measures of catchment urban impact: effective imperviousness (EI, the proportion of a catchment covered by impervious surfaces with direct connection to streams) or septic tank density (which affects stream water chemistry, particularly stream N concentrations). Denitrifying community structure was examined by comparing terminal restriction fragment length polymorphisms of nosZ genes in the sediments, as the nosZ gene codes for nitrous oxide reductase, the last step in the denitrification pathway. We also determined the chemical and physical characteristics of the streams that were best correlated with denitrifying community composition. EI was strongly correlated with community composition and sediment physical and chemical properties, while septic tank density was not. Sites with high EI were sandier, with less fine sediment and lower organic carbon content, higher sediment cations (calcium, sodium and magnesium) and water filterable reactive phosphorus concentrations. These were also the best small-scale environmental variables that explained denitrifying community composition. Among our study streams, which differed in the degree of urban stormwater impact, sediment grain size and carbon content are the most likely drivers of change in community composition. Denitrifying community composition is another in a long list of ecological indicators that suggest the profound degradation of streams is caused by urban stormwater runoff. While the relationships between denitrifying community composition and denitrification rates are yet to be

  16. Electrical properties of multiphase composites based on carbon nanotubes and an optimized clay content

    NASA Astrophysics Data System (ADS)

    Egiziano, Luigi; Lamberti, Patrizia; Spinelli, Giovanni; Tucci, Vincenzo; Guadagno, Liberata; Vertuccio, Luigi

    2016-05-01

    The experimental results concerning the characterization of a multiphase nanocomposite systems based on epoxy matrix, loaded with different amount of multi-walled carbon nanotubes (MWCNTs) and an optimized Hydrotalcite (HT) clay content (i.e. 0.6 wt%), duly identified by an our previous theoretical study based on Design of Experiment (DoE), are presented. Dynamic-mechanical analysis (DMA) reveal that even the introduction of higher HT loading (up to 1%wt) don't affect significantly the mechanical properties of the nanocomposites while morphological investigations show an effective synergy between clay and carbon nanotubes that leads to peculiar micro/nanostructures that favor the creation of the electrical conductive network inside the insulating resin. An electrical characterization is carried out in terms of DC electrical conductivity, percolation threshold (EPT) and frequency response in the range 10Hz-1MHz. In particular, the measurements of the DC conductivity allow to obtain the typical "percolation" curve also found for classical CNT-polymer mixtures and a value of about 2 S/m for the electrical conductivity is achieved at the highest considered CNTs concentration (i.e. 1 wt%). The results suggest that multiphase nanocomposites obtained incorporating dispersive nanofillers, in addition to the conductive one, may be a valid alternative to the polymer blends, to improve the properties of the polymeric materials thus able to meet high demands, particularly concerning their mechanical and thermal stability and electrical features required in the aircraft engineering.

  17. Relationship of subseafloor microbial diversity to sediment age and organic carbon content

    NASA Astrophysics Data System (ADS)

    Walsh, E. A.; Kirkpatrick, J. B.; Sogin, M. L.; D'Hondt, S. L.

    2013-12-01

    Our tag pyrosequencing investigation of four globally distant sites reveals sediment age and total organic carbon content to be significant components in understanding subseafloor diversity. Our sampling locations include two sites from high-productivity regions (Indian Ocean and Bering Sea) and two from moderate-productivity (eastern and central equatorial Pacific Ocean). Sediment from the high-productivity sites has much higher TOC than sediment from the moderate-productivity equatorial sites. We applied a high-resolution 16S V4-V6 tag pyrosequencing approach to 24 bacterial and 17 archaeal samples, totaling 602,502 reads. We identified1,291 archaeal and 15,910 bacterial OTUs (97%) from these reads. We analyzed bacterial samples from all four sites in addition to archaeal samples from our high productivity sites. These high productivity, high TOC sites have a pronounced methane-rich sulfate-free zone at depth from which archaea have been previously considered to dominate (Biddle et al., 2006). At all four locations, microbial diversity is highest near the seafloor and drops rapidly to low but stable values with increasing sediment depth. The depth at which diversity stabilizes varies greatly from site to site, but the age at which it stabilizes is relatively constant. At all four sites, diversity reaches low stable values a few hundred thousand years after sediment deposition. The sites with high total organic carbon (high productivity sites) generally exhibit higher diversity at each sediment age than the sites with lower total organic carbon (moderate-productivity sites). Archaeal diversity is lower than bacterial diversity at every sampled depth. Biddle, J.F., Lipp, J.S., Lever, M.A., Lloyd, K.G., Sørensen, K.B., Anderson, R. et al. (2006) Heterotrophic Archaea dominate sedimentary subsurface ecosystems off Peru. PNAS 103: 3846-3851.

  18. Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

    NASA Astrophysics Data System (ADS)

    Serrano, Oscar; Lavery, Paul S.; Duarte, Carlos M.; Kendrick, Gary A.; Calafat, Antoni; York, Paul H.; Steven, Andy; Macreadie, Peter I.

    2016-09-01

    The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e., silt and clay, particle sizes < 63 µm), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between Corg and mud contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast-growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relatively high soil Corg contents with relatively low mud contents (e.g., mud-Corg saturation) in bare sediments and Zostera, Halodule and Halophila meadows was related to significant allochthonous inputs of terrestrial organic matter, while higher contribution of seagrass detritus in Amphibolis and Posidonia meadows disrupted the correlation expected between soil Corg and mud contents. This study shows that mud is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil Corg content for scaling up purposes when

  19. The super-elastic Japanese NiTi alloy wire for use in orthodontics. Part III. Studies on the Japanese NiTi alloy coil springs.

    PubMed

    Miura, F; Mogi, M; Ohura, Y; Karibe, M

    1988-08-01

    Closed and open Japanese nickel titanium (NiTi) alloy coil springs were fabricated from the Japanese NiTi alloy wire. The closed coil springs were subjected to a tensile test and the open coil springs were subjected to a compression test to evaluate the mechanical properties. At the same time, a test with the commercially available steel coil springs also was done. It was clearly established that the Japanese NiTi alloy coil springs exhibited superior springback and super-elastic properties similar to the properties of the Japanese NiTi alloy arch wires. In addition, it was shown that the load value of super-elastic activity can be effectively controlled by changing the diameter of the wire, the size of lumen, the martensite transformation temperature, and the pitch of the open coil spring. The most important characteristic of the Japanese NiTi alloy coil springs is the ability to exert a very long range of constant light, continuous force. It is possible to use this coil selectively to obtain optimal tooth movement. PMID:3165245

  20. Enhancing Phenolic Contents and Antioxidant Potentials of Antidesma thwaitesianum by Supercritical Carbon Dioxide Extraction.

    PubMed

    Poontawee, Warut; Natakankitkul, Surapol; Wongmekiat, Orawan

    2015-01-01

    Supercritical fluid extraction (SFE) has increasingly gained attention as an alternative technique for extraction of natural products without leaving toxic residues in extracts. Antidesma thwaitesianum Muell. Arg. (Phyllanthaceae), or ma mao, has been reported to exhibit antioxidant health benefits due to its phenolic constituents. To determine whether SFE technique could impact on phenolic contents and associated antioxidant potentials, ripe fruits of Antidesma thwaitesianum (Phyllanthaceae) were extracted using supercritical carbon dioxide (SC-CO2) and conventional solvents (ethanol, water). The results showed that the SC-CO2 extract contained significantly higher yield, total phenolic, flavonoid, and proanthocyanidin contents than those obtained from ethanol and water. It also demonstrated the greatest antioxidant activities as assessed by ABTS radical cation decolorization, DPPH radical scavenging, and ferric reducing antioxidant power (FRAP) assays. Further analysis using high-performance liquid chromatography with diode array and mass spectrometry detectors (HPLC-DAD/MSD) revealed the presence of catechin as a major phenolic compound of Antidesma thwaitesianum (Phyllanthaceae), with the maximum amount detected in the SC-CO2 extract. These data indicate that SFE technology improves both quantity and quality of Antidesma thwaitesianum fruit extract. The findings added more reliability of using this technique to produce high added value products from this medicinal plant.

  1. Adsorption of tetracycline from aqueous solutions onto multi-walled carbon nanotubes with different oxygen contents

    PubMed Central

    Yu, Fei; Ma, Jie; Han, Sheng

    2014-01-01

    Oxidized multi-walled carbon nanotubes (MWCNTs) with different oxygen contents were investigated for the adsorption of tetracycline (TC) from aqueous solutions. As the surface oxygen content of the MWCNTs increased, the maximum adsorption capacity and adsorption coefficient of TC increased to the largest values and then decreased. The relation can be attributed to the interplay between the nanotubes' dispersibility and the water cluster formation upon TC adsorption. The overall adsorption kinetics of TC onto CNTs-3.2%O might be dependent on both intra-particle diffusion and boundary layer diffusion. The maximum adsorption capacity of TC on CNTs-3.2%O was achieved in the pH range of 3.3–8.0 due to formation of water clusters or H-bonds. Furthermore, the presence of Cu2+ could significantly enhanced TC adsorption at pH of 5.0. However, the solution ionic strength did not exhibit remarkable effect on TC adsorption. In addition, when pH is beyond the range (3.3–8.0), the electrostatic interactions caused the decrease of TC adsorption capacity. Our results indicate that surface properties and aqueous solution chemistry play important roles in TC adsorption on MWCNTs. PMID:24937315

  2. Enhancing Phenolic Contents and Antioxidant Potentials of Antidesma thwaitesianum by Supercritical Carbon Dioxide Extraction

    PubMed Central

    Poontawee, Warut; Natakankitkul, Surapol; Wongmekiat, Orawan

    2015-01-01

    Supercritical fluid extraction (SFE) has increasingly gained attention as an alternative technique for extraction of natural products without leaving toxic residues in extracts. Antidesma thwaitesianum Muell. Arg. (Phyllanthaceae), or ma mao, has been reported to exhibit antioxidant health benefits due to its phenolic constituents. To determine whether SFE technique could impact on phenolic contents and associated antioxidant potentials, ripe fruits of Antidesma thwaitesianum (Phyllanthaceae) were extracted using supercritical carbon dioxide (SC-CO2) and conventional solvents (ethanol, water). The results showed that the SC-CO2 extract contained significantly higher yield, total phenolic, flavonoid, and proanthocyanidin contents than those obtained from ethanol and water. It also demonstrated the greatest antioxidant activities as assessed by ABTS radical cation decolorization, DPPH radical scavenging, and ferric reducing antioxidant power (FRAP) assays. Further analysis using high-performance liquid chromatography with diode array and mass spectrometry detectors (HPLC-DAD/MSD) revealed the presence of catechin as a major phenolic compound of Antidesma thwaitesianum (Phyllanthaceae), with the maximum amount detected in the SC-CO2 extract. These data indicate that SFE technology improves both quantity and quality of Antidesma thwaitesianum fruit extract. The findings added more reliability of using this technique to produce high added value products from this medicinal plant. PMID:25977832

  3. Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy

    PubMed Central

    Agustina, Elsye; Goak, Jeungchoon; Lee, Suntae; Seo, Youngho; Park, Jun-Young; Lee, Naesung

    2015-01-01

    Iron catalysts have been used widely for the mass production of carbon nanotubes (CNTs) with high yield. In this study, UV/visible spectroscopy was used to determine the Fe catalyst content in CNTs using a colorimetric technique. Fe ions in solution form red–orange complexes with 1,10-phenanthroline, producing an absorption peak at λ=510 nm, the intensity of which is proportional to the solution Fe concentration. A series of standard Fe solutions were formulated to establish the relationship between optical absorbance and Fe concentration. Many Fe catalysts were microscopically observed to be encased by graphitic layers, thus preventing their extraction. Fe catalyst dissolution from CNTs was investigated with various single and mixed acids, and Fe concentration was found to be highest with CNTs being held at reflux in HClO4/HNO3 and H2SO4/HNO3 mixtures. This novel colorimetric method to measure Fe concentrations by UV/Vis spectroscopy was validated by inductively coupled plasma optical emission spectroscopy, indicating its reliability and applicability to asses Fe content in CNTs. PMID:26491641

  4. Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy.

    PubMed

    Agustina, Elsye; Goak, Jeungchoon; Lee, Suntae; Seo, Youngho; Park, Jun-Young; Lee, Naesung

    2015-10-01

    Iron catalysts have been used widely for the mass production of carbon nanotubes (CNTs) with high yield. In this study, UV/visible spectroscopy was used to determine the Fe catalyst content in CNTs using a colorimetric technique. Fe ions in solution form red-orange complexes with 1,10-phenanthroline, producing an absorption peak at λ=510 nm, the intensity of which is proportional to the solution Fe concentration. A series of standard Fe solutions were formulated to establish the relationship between optical absorbance and Fe concentration. Many Fe catalysts were microscopically observed to be encased by graphitic layers, thus preventing their extraction. Fe catalyst dissolution from CNTs was investigated with various single and mixed acids, and Fe concentration was found to be highest with CNTs being held at reflux in HClO4/HNO3 and H2SO4/HNO3 mixtures. This novel colorimetric method to measure Fe concentrations by UV/Vis spectroscopy was validated by inductively coupled plasma optical emission spectroscopy, indicating its reliability and applicability to asses Fe content in CNTs. PMID:26491641

  5. Effects of long-term compost application on carbon content and soil physical properties

    NASA Astrophysics Data System (ADS)

    Eden, Marie; Houot, Sabine

    2013-04-01

    Biological treatment through composting of organic wastes fulfils multiple purposes: it not only reduces the amount of waste stored in landfills but can also provide agricultural soils with organic amendments, which affect physicochemical soil properties and reduce the use of mineral fertilizers. However, the impacts of different types of amendments are not yet fully understood, as quantity and quality of the exogenous organic matter (EOM) applied vary greatly and numerous other parameters are affected as well, such as pH, heavy metal content, or nutrient availability. The objective of this project was to investigate the effect of different organic amendments - via simulations - on water holding capacity (WHC) and particularly plant available water (PAW), in regard to irrigation needs. The long-term field experiment "Qualiagro" (INRA - Veolia Environment collaboration) was established in Feucherolles, France in 1998, where five treatments were designed, each with two levels of mineral nitrogen (N) addition: minimal and optimal. Farmyard manure (FYM) and three types of compost - all applied every other year at a rate of 4 t carbon ha-1 - gave rise to varying organic carbon (OC) contents and were compared to a control treatment. The treatments changed the soil's OC content from initially ~10.5 g kg-1 to a range of 9.35 to 15.58 g kg-1. An increased OC content can enhance WHC by increasing total porosity/ reducing bulk density. The PAW - the difference between field capacity (FC) and permanent wilting point (WP); predicted with pedotransfer functions related to OC - increases, if the increase at FC is larger than that at WP. With a higher amount of PAW, the need to irrigate fields - to ensure sufficient water availability for plant growth - decreases. At the same time, soil bulk density (ρd) affects root growth; denser soils can lead to reduced rooting depth. Both of these effects were considered when employing a simple soil water balance model (BUDGET; http

  6. Regional prediction of soil organic carbon content over croplands using airborne hyperspectral data

    NASA Astrophysics Data System (ADS)

    Vaudour, Emmanuelle; Gilliot, Jean-Marc; Bel, Liliane; Lefebvre, Josias; Chehdi, Kacem

    2015-04-01

    This study was carried out in the framework of the Prostock-Gessol3 and the BASC-SOCSENSIT projects, dedicated to the spatial monitoring of the effects of exogenous organic matter land application on soil organic carbon storage. It aims at identifying the potential of airborne hyperspectral AISA-Eagle data for predicting the topsoil organic carbon (SOC) content of bare cultivated soils over a large peri-urban area (221 km2) with both contrasted soils and SOC contents, located in the western region of Paris, France. Soils comprise hortic or glossic luvisols, calcaric, rendzic cambisols and colluvic cambisols. Airborne AISA-Eagle data (400-1000 nm, 126 bands) with 1 m-resolution were acquired on 17 April 2013 over 13 tracks which were georeferenced. Tracks were atmospherically corrected using a set of 22 synchronous field spectra of both bare soils, black and white targets and impervious surfaces. Atmospherically corrected track tiles were mosaicked at a 2 m-resolution resulting in a 66 Gb image. A SPOT4 satellite image was acquired the same day in the framework of the SPOT4-Take Five program of the French Space Agency (CNES) which provided it with atmospheric correction. The land use identification system layer (RPG) of 2012 was used to mask non-agricultural areas, then NDVI calculation and thresholding enabled to map agricultural fields with bare soil. All 18 sampled sites known to be bare at this very date were correctly included in this map. A total of 85 sites sampled in 2013 or in the 3 previous years were identified as bare by means of this map. Predictions were made from the mosaic spectra which were related to topsoil SOC contents by means of partial least squares regression (PLSR). Regression robustness was evaluated through a series of 1000 bootstrap data sets of calibration-validation samples. The use of the total sample including 27 sites under cloud shadows led to non-significant results. Considering 43 sites outside cloud shadows only, median

  7. Improving the bioactivity of NiTi shape memory alloy by heat and alkali treatment

    NASA Astrophysics Data System (ADS)

    Qiang, Wei; Zhen-duo, Cui; Xian-jin, Yang; Jie, Shi

    2008-11-01

    TiO 2 films were formed on an NiTi alloy surface by heat treatment in air at 600 °C. Heat treated NiTi shape memory alloys were subsequently alkali treated with 1 M, 3 M and 5 M NaOH solutions respectively, to improve their bioactivity. Then treated NiTi samples were soaked in 1.5SBF to evaluate their in vitro performance. The results showed that the 3 M NaOH treatment is the most appropriate method. A large amount of apatite formed within 1 day's soaking in 1.5SBF, after 7 day's soaking TiO 2/HA composite layer formed on the NiTi surface. SEM, XRD, FT-IR and TEM results showed that the morphology and microstructure are similar to the human bone apatite.

  8. Modelling global change impacts on soil carbon contents of agro-silvo-pastoral Mediterranean systems

    NASA Astrophysics Data System (ADS)

    Lozano-García, Beatriz; Muñoz-Rojas, Miriam; Parras-Alcántara, Luis

    2016-04-01

    total of 38 sampling points were selected under two management practices and six different land uses: (1) MEOW-dehesa (D); (2) MEOW-dehesa + some pine trees (D+P); (3) MEOW-dehesa + some cork oaks (D+C); (4) MEOW-dehesa + some gall oaks (D + G); (5) MEOW-dehesa after a clarified process and transformed to olive grove but maintaining isolated oaks (OG) and (6) MEOW-dehesa after a clarified process and transformed to cereal pasture with isolated oaks (C). Preliminary results showed a high heterogeneity of SOC contents along the soil profile for different climate and land use scenarios. The methods used here can be easily implemented in other Mediterranean areas with available information on climate, site, soil and land use. Keywords: CarboSOIL model, land use change, climate change, soil depth, dehesa References: Abd-Elmabod, S.K., Muñoz-Rojas, M., Jordán, A., Anaya-Romero, M., De la Rosa, D., 2014. Modelling soil organic carbon stocks along topographic transects under climate change scenarios using CarboSOIL. Geophys. Res. Abstr. vol. 16 EGU2014-295-1, EGU General Assembly.) Álvaro-Fuentes, J., Easter, M., Paustian, K., 2012. Climate change effects on organic carbon storage in agricultural soils of northeastern Spain. Agric. Ecosyst. Environ. 155, 87-94. Corral-Fernández, R., Parras-Alcántara, L., Lozano-García, B. 2013. Stratification ratio of soil organic C, N and C:N in Mediterranean evergreen oak woodland with conventional and organic tillage. Agric. Ecosyst. Environ. 164, 252-259. Francaviglia, R., Coleman, K., Whitmore, A.P., Doro, L., Urracci, G., Rubino, M., Ledda, L., 2012. Changes in soil organic carbon and climate change - application of the RothC model in agrosilvo-pastoral Mediterranean systems. Agric. Syst. 112, 48- 54. IPCC, 2007. Technical summary. In: Climate Change 2007. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change http://www.ipcc.ch/. Lozano-García, B., Parras-Alcántara, L

  9. Impact of carbon, oxygen and sulfur content of microscale zerovalent iron particles on its reactivity towards chlorinated aliphatic hydrocarbons.

    PubMed

    Velimirovic, Milica; Larsson, Per-Olof; Simons, Queenie; Bastiaens, Leen

    2013-11-01

    Zerovalent iron (ZVI) abiotically degrades several chlorinated aliphatic hydrocarbons (CAHs) via reductive dechlorination, which offers perspectives for in situ groundwater remediation applications. The difference in reactivity between ZVI particles is often linked with their specific surface area. However, other parameters may influence the reactivity as well. Earlier, we reported for a set of microscale zerovalent iron (mZVI) particles the disappearance kinetic of different CAHs which were collected under consistent experimental conditions. In the present study, these kinetic data were correlated with the carbon, oxygen and sulfur content of mZVI particles. It was confirmed that not only the specific surface area affects the disappearance kinetic of CAHs, but also the chemical composition of the mZVI particles. The chemical composition, in addition, influences CAHs removal mechanism inducing sorption onto mZVI particles instead of dechlorination. Generally, high disappearance kinetic of CAHs was observed for particles containing less oxygen. A high carbon content, on the other hand, induced nonreactive sorption of the contaminants on the mZVI particles. To obtain efficient remediation of CAHs by mZVI particles, this study suggested that the carbon and oxygen content should not exceed 0.5% and 1% respectively. Finally, the efficiency of the mZVI particles may be improved to some extent by enriching them with sulfur. However, the impact of sulfur content on the reactivity of mZVI particles is less pronounced than that of the carbon and oxygen content.

  10. [Effects of tillage rotation and fertilization on soil aggregates and organic carbon content in corn field in Weibei Highland].

    PubMed

    Wang, Li; Li, Jun; Li, Juan; Bai, Wei-Xia

    2014-03-01

    A field experiment on effects of tillage rotation and fertilization on corn continuous cropping-practiced lands was carried out in Heyang of Shaanxi in 2007-2012. The tillage types included annual rotation of no-tillage and subsoiling (NT-ST), subsoiling and conventional tillage (ST-CT), or conventional tillage and no-tillage (CT-NT), and yearly practice of no tillage (NT-NT), subsoiling (ST-ST) or conventional tillage (CT-CT). The fertilization treatments included balanced fertilization, low-rate fertilization and conventional fertilization, which were separately practiced against the different tillage types. The experiment investigated compositions, mean mass diameters (MWD), geometrical mean diameters (GMD) and fraction dimension numbers (D) of soil aggregates in 0-40 cm soil and contents of organic carbon in 0-60 cm soil. The results indicated that: 1) The increased tillage intensity caused the reduced mechanical stability and content of soil aggregates and increased soil organic carbon loss. No-tillage or tillage rotation increased the MWD, GMD and contents of soil organic carbon and soil aggregates with diameters of more than 0.25 mm, but decreased D. Under the same fertilization treatment, the contents of soil aggregates with diameters of more than 0.25 mm were ranked in the order of NT-NT>NT-ST>NT-CT>ST-ST>CT-ST>CT-CT, and under the same tillage rotations, the soil aggregates were more stable with the balanced or low- rate fertilization than with the conventional fertilization. 2) Mathematical fractal dimension fitting of soil aggregates indicated that the fractal dimension numbers of soil aggregates ranged within 2.247-2.681 by dry sieving and 2.897-2.976 by wet sieving. In 0-30 cm soil, the fractal dimension numbers of soil aggregates were significantly lower under no-tillage or tillage rotation than under conventional tillage, and in 0-40 cm soil, the fractal dimensions of soil aggregates increased with soil depth, and tended to stabilize at the soil

  11. Influence of moisture content and temperature on degree of carbonation and the effect on Cu and Cr leaching from incineration bottom ash.

    PubMed

    Lin, Wenlin Yvonne; Heng, Kim Soon; Sun, Xiaolong; Wang, Jing-Yuan

    2015-09-01

    This study investigated the influence of moisture content and temperature on the degree of carbonation of municipal solid waste (MSW) incineration bottom ash (IBA) from two different incineration plants in Singapore. The initial rate of carbonation was affected by the nominal moisture content used. Carbonation temperature seemed to play a part in changing the actual moisture content of IBA during carbonation, which in turn affected the degree of carbonation. Results showed that 2h of carbonation was sufficient for the samples to reach a relatively high degree of carbonation that was close to the degree of carbonation observed after 1week of carbonation. Both Cu and Cr leaching also showed significant reduction after only 2h of carbonation. Therefore, the optimum moisture content and temperature were selected based on 2h of carbonation. The optimum moisture content was 15% for both incineration plants while the optimum temperature was different for the two incineration plants, at 35°C and 50°C. The effect on Cu and Cr leaching from IBA after accelerated carbonation was evaluated as a function of carbonation time. Correlation coefficient, Pearson's R, was used to determine the dominant leaching mechanism. The reduction in Cu leaching was found to be contributed by both formation of carbonate mineral and reduction of DOC leaching. On the other hand, Cr leaching seemed to be dominantly controlled by pH.

  12. A Study of Wear and Corrosion Resistance of Arc-Sprayed Ni-Ti Composite Coatings

    NASA Astrophysics Data System (ADS)

    Chang, C. H.; Jeng, M. C.; Su, C. Y.; Huang, T. S.

    2011-12-01

    In this study, the corrosion and wear performance of Ni-Ti composite coatings with distinct parameters were investigated. The coatings were prepared by arc spraying with Ti and Ni wires fed synchronously. Structural, surface morphological, and compositional analyses of the Ni-Ti composite coatings were performed using microhardness, SEM/EDS, XRD, and DTA analysis. Electrochemical AC impedance and potentiodynamic polarization tests were carried out to examine the anticorrosion performance of the coating. Ball-on-disc dry wear tests based on the ASTM G99 standard were performed at room temperature to evaluate the antiwear properties. The DTA and XRD analysis results indicated that some intermetallic compounds such as TiNi3 and Ni-Ti alloy were present within the Ni-Ti coating. The wear resistance of the Ni-Ti composite coating is superior to that of the Ni-sprayed coating but slightly inferior to that of the Ti-sprayed coating. The corrosion resistance of the arc-sprayed Ni-Ti coating is superior to that of Ti but inferior to that of Ni. The corrosion and wear performance of the composite coating are greatly influenced by the coating microstructure and thickness.

  13. The effect of electrical treatment on cyclic fatigue of NiTi instruments.

    PubMed

    Saghiri, Mohammad Ali; Asatourian, Armen; Garcia-Godoy, Franklin; Gutmann, James L; Lotfi, Mehrdad; Sheibani, Nader

    2014-01-01

    Dentists desire to use NiTi rotary instruments, which do not break inside the root canals of teeth, since the pieces from broken files are difficult to remove. The NiTi rotary instrument breakage is because of cyclic and torsional fatigue. Here the low-voltage (12 V) and high voltage (24 V) electrical treatments were used to enhance the cyclic fatigue of NiTi rotary instruments and increase their durability. In excremental groups, following electrical treatment samples of the NiTi instruments were rotated inside artificial root canals until they broke. Our results showed that electrical treatment with 12-V DC was effective in restoring NiTi instrument's resistance to cyclic fatigue. The scanning electron microscopy images and fractograph of samples exposed to 12-V electrical treatment showed a more regular texture over the surface with less dimpling on fractured site. These patterns can improve the super elasticity of tested devices during rotational movement, and delay the NiTi instruments separation in root canal preparations.

  14. In Situ Phase Evolution of Ni/Ti Reactive Multilayers

    NASA Astrophysics Data System (ADS)

    Cavaleiro, A. J.; Ramos, A. S.; Martins, R. M. S.; Baetz, C.; Vieira, M. T.; Braz Fernandes, F. M.

    2014-07-01

    Joining shape-memory alloys (SMA) to other materials is strongly required in order to enlarge their fields of application. Fusion welding induces strong compositional and microstructural changes that significantly affect the shape-memory effect and the superelastic behavior of these alloys. The exothermic and in some cases self-propagating character of some nano-multilayer reactions is explored in this study as an alternative for joining SMA. To follow these very fast reactions, high brilliance sources, such as synchrotron radiation, are required. In situ high-resolution x-ray diffraction data, giving the phase evolution sequence with temperature of the Ni/Ti multilayer thin films under study, are presented. A correlation between the multilayer design and the tendency for the sequence of phase formation is established.

  15. Energetics of Single Substitutional Impurities in NiTi

    NASA Technical Reports Server (NTRS)

    Good, Brian S.; Noebe, Ronald

    2003-01-01

    Shape-memory alloys are of considerable current interest, with applications ranging from stents to Mars rover components. In this work, we present results on the energetics of single substitutional impurities in B2 NiTi. Specifically, energies of Pd, Pt, Zr and Hf impurities at both Ni and Ti sites are computed. All energies are computed using the CASTEP ab initio code, and, for comparison, using the quantum approximate energy method of Bozzolo, Ferrante and Smith. Atomistic relaxation in the vicinity of the impurities is investigated via quantum approximate Monte Carlo simulation, and in cases where the relaxation is found to be important, the resulting relaxations are applied to the ab initio calculations. We compare our results with available experimental work.

  16. Elemental Mapping of NiTi with EFTEM

    SciTech Connect

    Wittig, J. E.; Bentley, James; Evans, Neal D; Somsen, Ch.; Eggeler, G.

    2005-01-01

    Martensitic transformations in Ni-rich NiTi shape memory alloys take place as multistage transformations. In Ni-rich alloys with an austenitic B2 matrix, coherent Ni{sub 4}Ti{sub 3} precipitates form from thermo-mechanical processing and affect the sequence of the martensitic transformation. Any composition inhomogenieties that develop during the evolution of the Ni{sub 4}Ti{sub 3} precipitates will have a large influence on the multistage martensitic transformations, since the martensite start temperature, M{sub s}, is strongly dependent on the Ni concentration of the matrix. Since concentration differences on the order of 0.5 at% are sufficient to influence the transformation, providing sufficiently accurate concentration profiles for meaningful structure-property correlations is a challenging experiment. This investigation employs elemental mapping by energy-filtered transmission electron microscopy (EFTEM) to attempt to measure the concentration profiles at these precipitate-matrix interfaces.

  17. Radiological image-guided placement of covered Niti-S stent for palliation of dysphagia in patients with cervical esophageal cancer.

    PubMed

    Fujita, Takeshi; Tanabe, Masahiro; Shimizu, Kensaku; Iida, Etsushi; Matsunaga, Naofumi

    2013-06-01

    The aim of this study was to evaluate the clinical effectiveness of covered Niti-S stent placement under multidetector CT and fluoroscopy guidance for the palliation of dysphagia in patients with cervical esophageal cancer. Under radiological imaging guidance using axial and sagittal CT scans, and fluoroscopy, Niti-S esophageal stents were placed in ten consecutive patients with complete obstruction caused by cervical esophageal cancer (9 men and 1 woman; age range = 54-79 years; mean age = 68.1 years) between February 2010 and December 2011. The procedure time and technical success rate were evaluated. Swallowing improvement was assessed by the following items: ability to eat and/or swallow (graded as follows: 3 = ability to eat normal diet, 2 = ability to eat semisolids, 1 = ability to swallow liquids, 0 = complete obstruction). Procedural and post-procedural complications were also evaluated. Survival (mean ± SD) was examined. The mean (±SD) procedure time was 40 ± 19 min (range = 21-69 min). Stent placement was technically successful in all patients; inadequate stent deployment did not occur in any case. Ability to eat and/or swallow was improved and scored 2.4 (score 3 in 5 cases, score 2 in 4 cases, score 1 in 1 case, and score 0 in no case) after stent placement. No major or post-procedural complications were encountered. The mean survival time was 131 ± 77 days (range = 31-259 days). Niti-S stents appeared to be a safe and effective device for the palliation of dysphagia caused by advanced cervical esophageal cancer. Multidetector CT and fluoroscopy image guidance helped the operators accurately place the stents in the cervical esophagus.

  18. Chemostratigraphies of carbon, oxygen and strontium isotopes and oxygen contents across the Precambrian-Cambrian boundary

    NASA Astrophysics Data System (ADS)

    Komiya, T.; Sawaki, Y.; Ishikawa, T.

    2007-12-01

    The Precambrian-Cambrian (PC-C) boundary is one of the most important intervals for evolution of life. However, the scarcity of well-preserved outcrops through the boundary makes it ambiguous to decode change of the surface environment and biological evolution. In south China, strata through the PC-C boundary are continuously exposed and contain many fossils, suitable for study of environmental and biological change. In addition, we conducted excavations at four sites of Three Gorge area to obtain continuous and fresh samples. We measured the delta13C, delta18O and 87Sr/86Sr values of the drill core samples and REE compositions of fresh carbonate rocks, respectively. We identified two positive and two negative isotope excursions of delta13Ccarb within this interval: a moderate increase from 0 to +2 permil and a subsequent dramatic drop to -7 permil at the PC-C boundary, and a continuous increase to +5 permil at the upper part of the Nemakit-Daldynian (ND) stage and the subsequent sharp decrease to -9 permil just below the basal Tommotian unconformity, respectively. The continuous pattern of the delta13C shift is irrespective of lithotype and is comparable to fragmented records of other sections within and outside of the Yangtze Platform, indicating that the profile represents global change of seawater chemistry. A chemostratigraphy of 87Sr/86Sr ratios of the drilled samples also displays a smooth curve and its large positive anomaly just below the PC-C boundary. The estimate of oxygen content of seawater from REE composition of carbonate minerals shows significant decreases around PC-C and ND-Tommotian boundaries, respectively. The combination of chemostratigraphies of delta13C, 87Sr/86Sr and pO2 indicates that the 87Sr/86Sr excursions preceded the delta13C negative excursion at PC-C boundary, and suggests that global regression or formation of the Gondwana supercontinent, evident in increase of influx of continental materials, caused biological depression together

  19. Effect of Pore Size and Porosity on the Biomechanical Properties and Cytocompatibility of Porous NiTi Alloys

    PubMed Central

    Jian, Yu-Tao; Yang, Yue; Tian, Tian; Stanford, Clark; Zhang, Xin-Ping; Zhao, Ke

    2015-01-01

    Five types of porous Nickel-Titanium (NiTi) alloy samples of different porosities and pore sizes were fabricated. According to compressive and fracture strengths, three groups of porous NiTi alloy samples underwent further cytocompatibility experiments. Porous NiTi alloys exhibited a lower Young’s modulus (2.0 GPa ~ 0.8 GPa). Both compressive strength (108.8 MPa ~ 56.2 MPa) and fracture strength (64.6 MPa ~ 41.6 MPa) decreased gradually with increasing mean pore size (MPS). Cells grew and spread well on all porous NiTi alloy samples. Cells attached more strongly on control group and blank group than on all porous NiTi alloy samples (p < 0.05). Cell adhesion on porous NiTi alloys was correlated negatively to MPS (277.2 μm ~ 566.5 μm; p < 0.05). More cells proliferated on control group and blank group than on all porous NiTi alloy samples (p < 0.05). Cellular ALP activity on all porous NiTi alloy samples was higher than on control group and blank group (p < 0.05). The porous NiTi alloys with optimized pore size could be a potential orthopedic material. PMID:26047515

  20. Effect of Pore Size and Porosity on the Biomechanical Properties and Cytocompatibility of Porous NiTi Alloys.

    PubMed

    Jian, Yu-Tao; Yang, Yue; Tian, Tian; Stanford, Clark; Zhang, Xin-Ping; Zhao, Ke

    2015-01-01

    Five types of porous Nickel-Titanium (NiTi) alloy samples of different porosities and pore sizes were fabricated. According to compressive and fracture strengths, three groups of porous NiTi alloy samples underwent further cytocompatibility experiments. Porous NiTi alloys exhibited a lower Young's modulus (2.0 GPa ~ 0.8 GPa). Both compressive strength (108.8 MPa ~ 56.2 MPa) and fracture strength (64.6 MPa ~ 41.6 MPa) decreased gradually with increasing mean pore size (MPS). Cells grew and spread well on all porous NiTi alloy samples. Cells attached more strongly on control group and blank group than on all porous NiTi alloy samples (p < 0.05). Cell adhesion on porous NiTi alloys was correlated negatively to MPS (277.2 μm ~ 566.5 μm; p < 0.05). More cells proliferated on control group and blank group than on all porous NiTi alloy samples (p < 0.05). Cellular ALP activity on all porous NiTi alloy samples was higher than on control group and blank group (p < 0.05). The porous NiTi alloys with optimized pore size could be a potential orthopedic material.

  1. Effects of carbon dioxide, water supply, and seasonality on terpene content and emission by Rosmarinus officinalis

    SciTech Connect

    Penuelas, J.; Llusia, J.

    1997-04-01

    Rosmarinus officinalis L. plants were grown under carbon dioxide concentrations of 350 and 700 {mu}mol (atmospheric CO{sub 2} and elevated CO{sub 2}) and under two levels of irrigation (high water and low water) from October 1, 1994 to May 31, 1996. Elevated CO{sub 2} led on increasingly larger monthly growth rates than the atmospheric CO{sub 2} treatments. The increase was 9.5% in spring 1995, 23% in summer 1995, and 53% in spring 1996 in the high-water treatments, whereas in low-water treatments the growth response to elevated CO{sub 2} was constrained until the second year spring, when there was a 47% increase. The terpene concentrations was slightly larger in the elevated CO{sub 2} treatments than in atmospheric CO{sub 2} treatments and reached a maximum 37% difference in spring 1996. There was no significant effect of water treatment, likely as a result of a mild low water treatment for a Mediterranean plant. Terpene concentrations increased throughout the period of study, indicating possible age effects. The most abundant terpenes were {alpha}-pinene, cineole, camphor, borneol, and verbenone, which represented about 75% of the total. No significant differences were found in the terpene composition of the plants in the different treatments or seasons. The emission of volatile terpenes was much larger in spring (about 75 {mu}g/dry wt/hr) than in autumn (about 10 {mu}g/dry wt/hr), partly because of higher temperature and partly because of seasonal effect, but no significant differences was found because of CO{sub 2} or water treatment. The main terpene emitted was {alpha}-pinene, which represented about 50% of the total. There was no clear correlation between content and emission, either quantitatively or qualitatively. More volatile terpenes were proportionally more important in the total emission than in total content and in autumn than in spring.

  2. Effect of electrolyte water content on the anodic passivation of lithium in IM LiC104-propylene carbonate

    NASA Astrophysics Data System (ADS)

    James, S. D.; Nagao, A. R.

    1982-06-01

    This work deals with the effect of aqueous contamination on the anode passivation of Li in 1M LiC10 4-propylene carbonate. Passivation occurs more readily with increasing electrolyte water content. Preliminary evidence suggests that anodic passivation may be due to anodic enrichment and eventual precipitation of LiC10 4 in the superficial anolyte layer.

  3. Effect of electrolyte water content on the anodic passivation of lithium in 1m lic104-propylene carbonate

    SciTech Connect

    James, S.D.; Nagao, A.R.

    1982-06-01

    This work deals with the effect of aqueous contamination on the anode passivation of Li in 1M LiC10/sup 4/-propylene carbonate. Passivation occurs more readily with increasing electrolyte water content. Preliminary evidence suggests that anodic passivation may be due to anodic enrichment and eventual precipitation of LiC10/sup 4/ in the superficial anolyte layer.

  4. Novel technique to suppress hydrocarbon contamination for high accuracy determination of carbon content in steel by FE-EPMA

    NASA Astrophysics Data System (ADS)

    Yamashita, Takako; Tanaka, Yuji; Yagoshi, Masayasu; Ishida, Kiyohito

    2016-07-01

    In multiphase steels, control of the carbon contents in the respective phases is the most important factor in alloy design for achieving high strength and high ductility. However, it is unusually difficult to determine the carbon contents in multiphase structures with high accuracy by electron probe microanalysis (EPMA) due to the unavoidable effect of hydrocarbon contamination during measurements. We have investigated new methods for suppressing hydrocarbon contamination during field emission (FE) EPMA measurements as well as a conventional liquid nitrogen trap. Plasma cleaner inside the specimen chamber results in a improvement of carbon-content determination by point analysis, increasing precision tenfold from the previous 0.1 mass%C to 0.01 mass%C. Stage heating at about 100 °C dramatically suppresses contamination growth during continuous point measurement and mapping. By the combination of above two techniques, we successfully visualized the two-dimensional carbon distribution in a dual-phase steel. It was also noted that the carbon concentrations at the ferrite/martensite interfaces were not the same across all interfaces, and local variation was observed. The developed technique is expected to be a powerful tool for understanding the mechanisms of mechanical properties and microstructural evolution, thereby contributing to the design of new steel products with superior properties.

  5. Novel technique to suppress hydrocarbon contamination for high accuracy determination of carbon content in steel by FE-EPMA

    PubMed Central

    Yamashita, Takako; Tanaka, Yuji; Yagoshi, Masayasu; Ishida, Kiyohito

    2016-01-01

    In multiphase steels, control of the carbon contents in the respective phases is the most important factor in alloy design for achieving high strength and high ductility. However, it is unusually difficult to determine the carbon contents in multiphase structures with high accuracy by electron probe microanalysis (EPMA) due to the unavoidable effect of hydrocarbon contamination during measurements. We have investigated new methods for suppressing hydrocarbon contamination during field emission (FE) EPMA measurements as well as a conventional liquid nitrogen trap. Plasma cleaner inside the specimen chamber results in a improvement of carbon-content determination by point analysis, increasing precision tenfold from the previous 0.1 mass%C to 0.01 mass%C. Stage heating at about 100 °C dramatically suppresses contamination growth during continuous point measurement and mapping. By the combination of above two techniques, we successfully visualized the two-dimensional carbon distribution in a dual-phase steel. It was also noted that the carbon concentrations at the ferrite/martensite interfaces were not the same across all interfaces, and local variation was observed. The developed technique is expected to be a powerful tool for understanding the mechanisms of mechanical properties and microstructural evolution, thereby contributing to the design of new steel products with superior properties. PMID:27431281

  6. Novel technique to suppress hydrocarbon contamination for high accuracy determination of carbon content in steel by FE-EPMA.

    PubMed

    Yamashita, Takako; Tanaka, Yuji; Yagoshi, Masayasu; Ishida, Kiyohito

    2016-01-01

    In multiphase steels, control of the carbon contents in the respective phases is the most important factor in alloy design for achieving high strength and high ductility. However, it is unusually difficult to determine the carbon contents in multiphase structures with high accuracy by electron probe microanalysis (EPMA) due to the unavoidable effect of hydrocarbon contamination during measurements. We have investigated new methods for suppressing hydrocarbon contamination during field emission (FE) EPMA measurements as well as a conventional liquid nitrogen trap. Plasma cleaner inside the specimen chamber results in a improvement of carbon-content determination by point analysis, increasing precision tenfold from the previous 0.1 mass%C to 0.01 mass%C. Stage heating at about 100 °C dramatically suppresses contamination growth during continuous point measurement and mapping. By the combination of above two techniques, we successfully visualized the two-dimensional carbon distribution in a dual-phase steel. It was also noted that the carbon concentrations at the ferrite/martensite interfaces were not the same across all interfaces, and local variation was observed. The developed technique is expected to be a powerful tool for understanding the mechanisms of mechanical properties and microstructural evolution, thereby contributing to the design of new steel products with superior properties. PMID:27431281

  7. Lowering the power consumption of Ni-Ti shape memory alloy

    NASA Astrophysics Data System (ADS)

    Villanueva, Alex; Gupta, Shashaak; Priya, Shashank

    2012-04-01

    Shape memory alloy (SMA) wires are capable of providing contractile strain mimicking the functionality of muscle fibers. They are promising for the development of biomimetic robots due to their high power density and desired form factor. However, they suffer from significantly high power consumption. The focus of this paper was to address this drawback associated with SMAs. Two different parameters were investigated in this study: i) lowering of the martensite to austentite phase transition temperatures and ii) the reduction of the thermal hysteresis. For an equiatomic Ni-Ti alloy, replacing nickel with 10 at% copper reduces the thermal hysteresis by 50% or more. For Ni- Ti alloys with nickel content greater than 50 at%, transition temperature decreases linearly at a rate of 100 °C/Ni at%. Given these two power reducing factors, an alloy with composition of Ni40+xTi50-xCu10 was synthesized with x = 0, +/-1, +/-2, +/-3, +/-4, +/-5. Metal powders were melted in an argon atmosphere using an RF induction furnace to produce ingots. All the synthesized samples were characterized by differential scanning calorimetric (DSC) analysis to reveal martensite to austenite and austenite to martensite transition temperatures during heating and cooling cycles respectively. Scanning electron microscopy (SEM) was conducted to identify the density and microstructure of the fractured samples. The alloy composition and synthesis method presented in this preliminary work shows the possibility of achieving low power consuming, high performance SMAs.

  8. Easy assessment of the biocompatibility of Ni-Ti alloys by in vitro cell culture experiments on a functionally graded Ni-NiTi-Ti material.

    PubMed

    Bogdanski, Denise; Köller, Manfred; Müller, Dietmar; Muhr, Gert; Bram, Martin; Buchkremer, Hans Peter; Stöver, Detlev; Choi, Jongsik; Epple, Matthias

    2002-12-01

    The biocompatibility of nickel-titanium alloys was investigated by single-culture experiments on functionally graded samples with a stepwise change in composition from pure nickel to pure titanium, including an Ni-Ti shape memory alloy for a 50:50 mixture. This approach permitted a considerable decrease of experimental resources by simultaneously studying a full variation of composition. The results indicate a good biocompatibility for a nickel content up to about 50%. The cells used in the biocompatibility studies comprised osteoblast-like osteosarcoma cells (SAOS-2, MG-63), primary human osteoblasts (HOB), and murine fibroblasts (3T3).

  9. Pyrogenic Carbon in soils: a literature-based inventory and a global estimation of its content in soil organic carbon and stocks

    NASA Astrophysics Data System (ADS)

    Reisser, Moritz; Purves, Ross; Schmidt, Michael W. I.; Abiven, Samuel

    2016-08-01

    Pyrogenic carbon (PyC) is considered one of the most stable components in soil and can represent more than 30% of total soil organic carbon (SOC). However, few estimates of global PyC stock or distribution exist and thus PyC is not included in any global carbon cycle models, despite its potential major relevance for the soil pool. To obtain a global picture, we reviewed the literature for published PyC content in SOC data. We generated the first PyC database including more than 560 measurements from 55 studies. Despite limitations due to heterogeneous distribution of the studied locations and gaps in the database, we were able to produce a worldwide PyC inventory. We found that global PyC represent on average 13.7% of the SOC and can be even up to 60%, making it one of the largest groups of identifiable compounds in soil, together with polysaccharides. We observed a consistent range of PyC content in SOC, despite the diverse methods of quantification. We tested the PyC content against different environmental explanatory variables: fire and land use (fire characteristics, land use, net primary productivity), climate (temperature, precipitation, climatic zones, altitude) and pedogenic properties (clay content, pH, SOC content). Surprisingly, soil properties explain PyC content the most. Soils with clay content higher than 50% contain significantly more PyC (> 30% of the SOC) than with clay content lower than 5% (< 6% of the SOC). Alkaline soils contain at least 50% more PyC than acidic soils. Furthermore, climatic conditions, represented by climatic zone or mean temperature or precipitation, correlate significantly with the PyC content. By contrast, fire characteristics could only explain PyC content, if site-specific information was available. Datasets derived from remote sensing did not explain the PyC content. To show the potential of this database, we used it in combination with other global datasets to create a global worldwide PyC content and a stock estimation

  10. Determination by near infrared microscopy of the nitrogen and carbon content of tomato (Solanum lycopersicum L.) leaf powder

    PubMed Central

    Lequeue, Gauthier; Draye, Xavier; Baeten, Vincent

    2016-01-01

    Near infrared microscopy (NIRM) has been developed as a rapid technique to predict the chemical composition of foods, reduce analytical costs and time and ease sample preparation. In this study, NIRM has been evaluated as an alternative to classical chemical analysis to determine the nitrogen and carbon content of small samples of tomato (Solanum lycopersicum L.) leaf powder. Near infrared spectra were obtained by NIRM for independent leaf samples collected on 216 plants grown under six different levels of nitrogen. From these, 30 calibration and 30 validation samples covering the spectral range of the whole set were selected and their nitrogen and carbon contents were determined by a reference method. The calibration model obtained for nitrogen content proved to be excellent, with a coefficient of determination in calibration (R2c) higher than 0.9 and a ratio of performance to deviation (RPDc) higher than 3. Statistical indicators of prediction using the validation set were also very high (R2p values > 0.90). However, the calibration model obtained for carbon content was much less satisfactory (R2c < 0.50). NIRM appears as a promising and suitable tool for a rapid, non-destructive and reliable determination of nitrogen content of tiny samples of tomato leaf powder. PMID:27634485

  11. Determination by near infrared microscopy of the nitrogen and carbon content of tomato (Solanum lycopersicum L.) leaf powder.

    PubMed

    Lequeue, Gauthier; Draye, Xavier; Baeten, Vincent

    2016-01-01

    Near infrared microscopy (NIRM) has been developed as a rapid technique to predict the chemical composition of foods, reduce analytical costs and time and ease sample preparation. In this study, NIRM has been evaluated as an alternative to classical chemical analysis to determine the nitrogen and carbon content of small samples of tomato (Solanum lycopersicum L.) leaf powder. Near infrared spectra were obtained by NIRM for independent leaf samples collected on 216 plants grown under six different levels of nitrogen. From these, 30 calibration and 30 validation samples covering the spectral range of the whole set were selected and their nitrogen and carbon contents were determined by a reference method. The calibration model obtained for nitrogen content proved to be excellent, with a coefficient of determination in calibration (R(2)c) higher than 0.9 and a ratio of performance to deviation (RPDc) higher than 3. Statistical indicators of prediction using the validation set were also very high (R(2)p values > 0.90). However, the calibration model obtained for carbon content was much less satisfactory (R(2)c < 0.50). NIRM appears as a promising and suitable tool for a rapid, non-destructive and reliable determination of nitrogen content of tiny samples of tomato leaf powder. PMID:27634485

  12. Manifestation of coherent magnetic anisotropy in a carbon nanotube matrix with low ferromagnetic nanoparticle content

    NASA Astrophysics Data System (ADS)

    Danilyuk, A. L.; Komissarov, I. V.; Labunov, V. A.; Le Normand, F.; Derory, A.; Hernandez, J. M.; Tejada, J.; Prischepa, S. L.

    2015-02-01

    The influence of the magnetic medium can lead to peculiar interaction between ferromagnetic nanoparticles (NPs). Most research in this area involves analysis of the interplay between magnetic anisotropy and exchange coupling. Increasing the average interparticle distance leads to the dominant role of the random magnetic anisotropy. Here we study the interparticle interaction in a carbon nanotube (CNT) matrix with low ferromagnetic NP content. Samples were synthesized by floating catalyst chemical vapor deposition. We found that below some critical NP concentration, when NPs are intercalated only inside CNTs, and at low temperatures, the extended magnetic order, of up to 150 nm, presents in our samples. It is shown by analyzing the correlation functions of the magnetic anisotropy axes that the extended order is not simply due to random anisotropy but is associated with the coherent magnetic anisotropy, which is strengthened by the CNT alignment. With increasing temperature the extended magnetic order is lost. Above the critical NP concentration, when NPs start to be intercalated not only into inner CNT channels, but also outside CNTs, the coherent anisotropy weakens and the exchange coupling dominates in the whole temperature range. We can make a connection with the various correlation functions using the generalized expression for the law of the approach to saturation and show that these different correlation functions reflect the peculiarities in the interparticle interaction inside CNTs. Moreover, we can extract such important micromagnetic parameters like the exchange field, local fields of random and coherent anisotropies, as well as their temperature and NP concentration dependencies.

  13. Short-range vertical variation in organic carbon, carbonate carbon, total sulfur contents and Munsell color values in a core from the Upper Pennsylvanian Stark Shale Member of the Dennis Limestone, Wabaunsee County, Kansas

    USGS Publications Warehouse

    Stanton, M.R.; Leventhal, Joel S.; Hatch, Joseph R.

    1983-01-01

    Organic carbon, total sulfur, carbonate carbon and Munsell color value were determined for 21 successive samples from a 53-cm-thick section of drill core. These samples are from the Stark Shale Member of the Dennis Limestone of Upper Pennsylvanian age, Wabaunsee County, Kansas. The data confirm previous results (Hosterman and Whitlow, 1981) which showed that a limited relationship of color value to organic carbon exists for shales containing about 7 percent or less organic carbon. For samples with 7 percent or more organic carbon, color values are nearly all the same. The color value is useful in screening samples before trace element analysis and in estimating the organic carbon content and metal potential of the shale (Leventhal and others, 1982).

  14. Launch Load Resistant Spacecraft Mechanism Bearings Made From NiTi Superelastic Intermetallic Materials

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Moore, Lewis E., III

    2014-01-01

    Compared to conventional bearing materials (tool steel and ceramics), emerging Superelastic Intermetallic Materials (SIMs), such as 60NiTi, have significantly lower elastic modulus and enhanced strain capability. They are also immune to atmospheric corrosion (rusting). This offers the potential for increased resilience and superior ability to withstand static indentation load without damage. In this paper, the static load capacity of hardened 60NiTi 50-mm-bore ball bearing races are measured to correlate existing flat-plate indentation load capacity data to an actual bearing geometry through the Hertz stress relations. The results confirmed the validity of using the Hertz stress relations to model 60NiTi contacts; 60NiTi exhibits a static stress capability (approximately 3.1 GPa) between that of 440C (2.4 GPa) and REX20 (3.8 GPa) tool steel. When the reduced modulus and extended strain capability are taken into account, 60NiTi is shown to withstand higher loads than other bearing materials. To quantify this effect, a notional space mechanism, a 5-kg mass reaction wheel, was modeled with respect to launch load capability when supported on standard (catalogue geometry) design 440C; 60NiTi and REX20 tool steel bearings. For this application, the use of REX20 bearings increased the static load capability of the mechanism by a factor of three while the use of 60NiTi bearings resulted in an order of magnitude improvement compared to the baseline 440C stainless steel bearings

  15. Modelling global change impacts on soil carbon contents of agro-silvo-pastoral Mediterranean systems

    NASA Astrophysics Data System (ADS)

    Lozano-García, Beatriz; Muñoz-Rojas, Miriam; Parras-Alcántara, Luis

    2016-04-01

    total of 38 sampling points were selected under two management practices and six different land uses: (1) MEOW-dehesa (D); (2) MEOW-dehesa + some pine trees (D+P); (3) MEOW-dehesa + some cork oaks (D+C); (4) MEOW-dehesa + some gall oaks (D + G); (5) MEOW-dehesa after a clarified process and transformed to olive grove but maintaining isolated oaks (OG) and (6) MEOW-dehesa after a clarified process and transformed to cereal pasture with isolated oaks (C). Preliminary results showed a high heterogeneity of SOC contents along the soil profile for different climate and land use scenarios. The methods used here can be easily implemented in other Mediterranean areas with available information on climate, site, soil and land use. Keywords: CarboSOIL model, land use change, climate change, soil depth, dehesa References: Abd-Elmabod, S.K., Muñoz-Rojas, M., Jordán, A., Anaya-Romero, M., De la Rosa, D., 2014. Modelling soil organic carbon stocks along topographic transects under climate change scenarios using CarboSOIL. Geophys. Res. Abstr. vol. 16 EGU2014-295-1, EGU General Assembly.) Álvaro-Fuentes, J., Easter, M., Paustian, K., 2012. Climate change effects on organic carbon storage in agricultural soils of northeastern Spain. Agric. Ecosyst. Environ. 155, 87-94. Corral-Fernández, R., Parras-Alcántara, L., Lozano-García, B. 2013. Stratification ratio of soil organic C, N and C:N in Mediterranean evergreen oak woodland with conventional and organic tillage. Agric. Ecosyst. Environ. 164, 252-259. Francaviglia, R., Coleman, K., Whitmore, A.P., Doro, L., Urracci, G., Rubino, M., Ledda, L., 2012. Changes in soil organic carbon and climate change - application of the RothC model in agrosilvo-pastoral Mediterranean systems. Agric. Syst. 112, 48- 54. IPCC, 2007. Technical summary. In: Climate Change 2007. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change http://www.ipcc.ch/. Lozano-García, B., Parras-Alcántara, L

  16. Microscale characterisation of stochastically reconstructed carbon fiber-based Gas Diffusion Layers; effects of anisotropy and resin content

    NASA Astrophysics Data System (ADS)

    Yiotis, Andreas G.; Kainourgiakis, Michael E.; Charalambopoulou, Georgia C.; Stubos, Athanassios K.

    2016-07-01

    A novel process-based methodology is proposed for the stochastic reconstruction and accurate characterisation of Carbon fiber-based matrices, which are commonly used as Gas Diffusion Layers in Proton Exchange Membrane Fuel Cells. The modeling approach is efficiently complementing standard methods used for the description of the anisotropic deposition of carbon fibers, with a rigorous model simulating the spatial distribution of the graphitized resin that is typically used to enhance the structural properties and thermal/electrical conductivities of the composite Gas Diffusion Layer materials. The model uses as input typical pore and continuum scale properties (average porosity, fiber diameter, resin content and anisotropy) of such composites, which are obtained from X-ray computed microtomography measurements on commercially available carbon papers. This information is then used for the digital reconstruction of realistic composite fibrous matrices. By solving the corresponding conservation equations at the microscale in the obtained digital domains, their effective transport properties, such as Darcy permeabilities, effective diffusivities, thermal/electrical conductivities and void tortuosity, are determined focusing primarily on the effects of medium anisotropy and resin content. The calculated properties are matching very well with those of Toray carbon papers for reasonable values of the model parameters that control the anisotropy of the fibrous skeleton and the materials resin content.

  17. The Spatial Distribution of Carbon Dust in the Early Solar Nebula and the Carbon Content of Planetesimals

    NASA Astrophysics Data System (ADS)

    Gail, H.-P.; Trieloff, M.

    2016-08-01

    The oxidation and pyrolysis processes in the chemically active regions of the Solar Nebula are considered that are responsible for the destruction of the pristine carbon inherited from the ISM and its conversion to hydrocarbons and ultimately to CO.

  18. [Effects of conservation tillage and weed control on soil water and organic carbon contents in winter wheat field].

    PubMed

    Han, Hui-Fang; Ning, Tang-Yuan; Li, Zeng-Jia; Tian, Shen-Zhong; Wang, Yu; Zhong, Wei-Lei; Tian, Xin-Xin

    2011-05-01

    Taking a long-term (since 2004) straw-returning winter wheat field as the object, an investigation was made in the wheat growth seasons of 2008-2009 and 2009-2010 to study the effects of different tillage methods (rotary tillage, harrow tillage, no-tillage, subsoil tillage, and conventional tillage) and weed management on the soil water and organic carbon contents. No matter retaining or removing weeds, the weed density under subsoil tillage and no-tillage was much higher than that under rotary tillage, harrow tillage, and conventional tillage. From the jointing to the milking stage of winter wheat, retaining definite amounts of weeds, no matter which tillage method was adopted, could significantly increase the 0-20 cm soil water content, suggesting the soil water conservation effect of retaining weeds. Retaining weeds only increased the soil organic carbon content in 0-20 cm layer at jointing stage. At heading and milking stages, the soil organic carbon contents in 0-20, 20-40, and 40-60 cm layers were lower under weed retaining than under weed removal. Under the conditions of weed removal, the grain yield under subsoil tillage increased significantly, compared with that under the other four tillage methods. Under the conditions of weed retaining, the grain yield was the highest under rotary tillage, and the lowest under conventional tillage.

  19. Influence of dissolved organic carbon content on modelling natural organic matter acid-base properties.

    PubMed

    Garnier, Cédric; Mounier, Stéphane; Benaïm, Jean Yves

    2004-10-01

    Natural organic matter (NOM) behaviour towards proton is an important parameter to understand NOM fate in the environment. Moreover, it is necessary to determine NOM acid-base properties before investigating trace metals complexation by natural organic matter. This work focuses on the possibility to determine these acid-base properties by accurate and simple titrations, even at low organic matter concentrations. So, the experiments were conducted on concentrated and diluted solutions of extracted humic and fulvic acid from Laurentian River, on concentrated and diluted model solutions of well-known simple molecules (acetic and phenolic acids), and on natural samples from the Seine river (France) which are not pre-concentrated. Titration experiments were modelled by a 6 acidic-sites discrete model, except for the model solutions. The modelling software used, called PROSECE (Programme d'Optimisation et de SpEciation Chimique dans l'Environnement), has been developed in our laboratory, is based on the mass balance equilibrium resolution. The results obtained on extracted organic matter and model solutions point out a threshold value for a confident determination of the studied organic matter acid-base properties. They also show an aberrant decreasing carboxylic/phenolic ratio with increasing sample dilution. This shift is neither due to any conformational effect, since it is also observed on model solutions, nor to ionic strength variations which is controlled during all experiments. On the other hand, it could be the result of an electrode troubleshooting occurring at basic pH values, which effect is amplified at low total concentration of acidic sites. So, in our conditions, the limit for a correct modelling of NOM acid-base properties is defined as 0.04 meq of total analysed acidic sites concentration. As for the analysed natural samples, due to their high acidic sites content, it is possible to model their behaviour despite the low organic carbon concentration.

  20. Relative Content of Black Carbon in Submicron Aerosol as a Sign of the Effect of Forest Fire Smokes

    SciTech Connect

    Kozlov, V.S.; Panchenko, M.V.; Yauscheva, E.P.

    2005-03-18

    Biomass burning occurs often in regions containing vast forest tracts and peat-bogs. These processes are accompanied by the emission of a large amount of aerosol particles and crystal carbon (black carbon [BC], soot). BC is the predominant source of solar absorption in atmospheric aerosol, which impacts climate. (Jacobson 2001; Rozenberg 1982). In this paper, we analyze the results of laboratory and field investigations that focused on the relative content of BC in aerosol particles. Main attention is given to the study of possibility using this parameter as an informative sign for estimating the effect of remote forest fire smokes on the near-ground aerosol composition.

  1. Challenges During Microstructural Analysis and Mechanical Testing of Small-Scale Pseudoelastic NiTi Structures

    NASA Astrophysics Data System (ADS)

    Hahn, S.; Wagner, M. F.-X.

    2016-06-01

    Most investigations on NiTi-based shape memory alloys involve large-scale bulk material; knowledge about the martensitic transformation in small-scale NiTi structures is still limited. In this paper, we study the microstructures of thin NiTi layers and their mechanical properties, and we discuss typical challenges that arise when experiments are performed on small samples. A physical vapor deposition (PVD) process was used to deposit thin NiTi wires with a cross section of 15 × 15 μm2 and dogbone-shaped samples 5 × 500 μm2. Microstructural properties were characterized by X-ray diffraction, electron backscatter diffraction, and scanning electron microscopy. Moreover, tensile tests were performed using optical strain measurements in order to observe martensite band formation during cyclic loading. The surfaces of the crystalline wires reflect the columnar growth of NiTi during deposition. The wires exhibit pseudoelastic material behavior during tensile testing. Fracture typically occurs along the columns because the column growth direction is perpendicular to the straining direction. Electropolishing removes these local stress raisers and hence increases fracture strains. Our results demonstrate that the pseudoelastic properties of the PVD-processed materials agree well with those of conventional NiTi, and that they provide new opportunities to study the fundamentals of martensitic transformation in small-scale model systems.

  2. Effect of temperature on the orthodontic clinical applications of niti closed-coil springs

    PubMed Central

    Espinar-Escalona, Eduardo; Llamas-Carreras, José M.; Barrera-Mora, José M.; Abalos-Lasbrucci, Camilo

    2013-01-01

    NiTi spring coils were used to obtain large deformation under a constant force. The device consists on a NiTi coil spring, superelastic at body temperature, in order to have a stress plateau during the austenitic retransformation during the unloading. The temperature variations induced changes in the spring force. Objectives: The aim of this study is to investigate the effect of the temperature variations in the spring forces and corrosion behaviour simulating the ingestion hot/cold drinks and food. Study Design: The springs were subjected to a tensile force using universal testing machine MTS-Adamel (100 N load cell). All tests were performed in artificial saliva maintained at different temperatures. The corrosion tests were performed according to the ISO-standard 10993-15:2000. Results: The increase in temperature of 18oC induced an increase in the spring force of 30%. However, when the temperature returns to 37oC the distraction force recovers near the initial level. After cooling down the spring to 15oC, the force decreased by 46%. This investigation show as the temperature increase, the corrosion potential shifts towards negative values and the corrosion density is rising. Conclusions: The changes of the temperatures do not modify the superelastic behaviour of the NiTi closed-coil springs. The corrosion potential of NiTi in artificial saliva is decreasing by the rise of the temperatures. Key words:Superelasticity, NiTi, springs, orthodontic, coils, recovery, temperature. PMID:23722142

  3. Electrophoretic deposition of double-layer HA/Al composite coating on NiTi.

    PubMed

    Karimi, Esmaeil; Khalil-Allafi, Jafar; Khalili, Vida

    2016-01-01

    In order to improve the bioactivity of NiTi alloys, which are being known as the suitable materials for biomedical applications, numerous NiTi disks were electrophoretically coated by hetero-coagulated hydroxyapatite/aluminum composite coatings in three main voltages from suspensions with different Al concentrations. In this paper, the amount of Ni ions release and bioactivity of prepared samples as well as bonding strength of the coating to substrate were investigated. The surface characterization of the coating by XRD, EDX, SEM, and FTIR showed that HA particles bonded by Al particles. It caused the formation of a free crack coating on NiTi disks. Moreover, the bonding strength of HA/Al coatings to NiTi substrate were improved by two times as compared to that of the pure HA coatings. Immersing of coated samples in SBF for 1 week showed that apatite formation ability was improved on HA/Al composite coating and Ni ions release from the surface of composite coating decreased. These results induce the appropriate bioactivity and biocompatibility of the deposited HA/Al composite coatings on NiTi disks.

  4. Electrophoretic deposition of double-layer HA/Al composite coating on NiTi.

    PubMed

    Karimi, Esmaeil; Khalil-Allafi, Jafar; Khalili, Vida

    2016-01-01

    In order to improve the bioactivity of NiTi alloys, which are being known as the suitable materials for biomedical applications, numerous NiTi disks were electrophoretically coated by hetero-coagulated hydroxyapatite/aluminum composite coatings in three main voltages from suspensions with different Al concentrations. In this paper, the amount of Ni ions release and bioactivity of prepared samples as well as bonding strength of the coating to substrate were investigated. The surface characterization of the coating by XRD, EDX, SEM, and FTIR showed that HA particles bonded by Al particles. It caused the formation of a free crack coating on NiTi disks. Moreover, the bonding strength of HA/Al coatings to NiTi substrate were improved by two times as compared to that of the pure HA coatings. Immersing of coated samples in SBF for 1 week showed that apatite formation ability was improved on HA/Al composite coating and Ni ions release from the surface of composite coating decreased. These results induce the appropriate bioactivity and biocompatibility of the deposited HA/Al composite coatings on NiTi disks. PMID:26478383

  5. Novel micro-patterning processes for thin film NiTi vascular devices

    NASA Astrophysics Data System (ADS)

    Chun, Y. J.; Levi, D. S.; Mohanchandra, K. P.; Fishbein, M. C.; Carman, G. P.

    2010-10-01

    In order to create microscale features in thin film NiTi for use in vascular endografts, a novel 'lift-off process' was developed for use with deep reactive ion etching. A wet etching approach is compared to two variations of this new 'lift-off' process. The first lift-off process (lift-off I) used Si posts to define the features of NiTi film deposited on the Si substrate. This method produced fractures in the NiTi when the film was released. The lift-off II process used Si islands as substrate for the film while the Si wafer defined the specific geometric features. Lift-off II process allowed for the creation of various shape patterns (i.e., ellipse, diamond, circle, square, etc) in the range of 5-180 µm. The lift-off II process produced smooth and well aligned micro-patterns in thin film NiTi without the undercutting found in wet etching techniques. The micro-patterned thin film NiTi formed from the lift-off II process was used to cover a stent. In vivo tests were performed to evaluate the endothelialization though patterned thin films. Angiography, histopathology and SEM showed patency of the artery and uniformly promoted endothelial layer covering without thrombosis in both a medium and small artery.

  6. Monitoring Tensile Fatigue of Superelastic NiTi Wire in Liquids by Electrochemical Potential

    NASA Astrophysics Data System (ADS)

    Racek, Jan; Stora, Marc; Šittner, Petr; Heller, Luděk; Kopeček, Jaromir; Petrenec, Martin

    2015-06-01

    Fatigue of superelastic NiTi wires was investigated by cyclic tension in simulated biofluid. The state of the surface of the fatigued NiTi wire was monitored by following the evolution of the electrochemical open circuit potential (OCP) together with macroscopic stresses and strains. The ceramic TiO2 oxide layer on the NiTi wire surface cannot withstand the large transformation strain and fractures in the first cycle. Based on the analysis of the results of in situ OCP experiments and SEM observation of cracks, it is claimed that the cycled wire surface develops mechanochemical reactions at the NiTi/liquid interface leading to cumulative generation of hydrogen, uptake of the hydrogen by the NiTi matrix, local loss of the matrix strength, crack transfer into the NiTi matrix, accelerated crack growth, and ultimately to the brittle fracture of the wire. Fatigue degradation is thus claimed to originate from the mechanochemical processes occurring at the excessively deforming surface not from the accumulation of defects due to energy dissipative bulk deformation processes. Ironically, combination of the two exciting properties of NiTi—superelasticity due to martensitic transformation and biocompatibility due to the protective TiO2 surface oxide layer—leads to excessive fatigue damage during cyclic mechanical loading in biofluids.

  7. Fiber laser micromachining of thin NiTi tubes for shape memory vascular stents

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Li, Dong Bo; Tong, Yi Fei; Zhu, Yu Fu

    2016-07-01

    Nickel titanium (NiTi) alloy has widely been used in the vascular stent manufacturing due to its excellent properties. Neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is commonly used for the preparation of metal vascular stents. Recently, fiber lasers have been used for stent profiling for better cutting quality. To investigate the cutting-kerf characters of NiTi vascular stents fabricated by fiber laser cutting, laser cutting experiments with thin NiTi tubes were conducted in this study, while NiTi sheets were used in other fiber laser cutting studies. Different with striation topography, new topographies such as layer topography and topography mixed with layers and striations were observed, and the underlying reason for new topographies was also discussed. Comparative research on different topographies was conducted through analyzing the surface roughness, kerf width, heat-affected zone (HAZ) and dross formation. Laser cutting process parameters have a comprehensive influence on the cutting quality; in this study, the process parameters' influences on the cutting quality were studied from the view of power density along the cutting direction. The present research provides a guideline for improving the cutting quality of NiTi vascular stents.

  8. Numerical Study on the Influence of Material Characteristics on Ni-Ti Endodontic Instrument Performance

    NASA Astrophysics Data System (ADS)

    Petrini, Lorenza; Necchi, Silvia; Taschieri, Silvio; Migliavacca, Francesco

    2009-08-01

    Ni-Ti rotary endodontic instruments ( files) are used in dentistry during the endodontic treatment to shape the root canal of the tooth while removing the pulp when infected. Up to now, the studies for evaluating their performances and drawbacks were mainly limited to experimental tests on product flexural and torsional resistance. This work exploits computational analyses for investigating the effects of materials with different mechanical properties on the behavior of rotary endodontic instruments. The aim is to understand the appropriate material choice to reduce the criticality of the treatment in particular clinical conditions. In particular, the interaction between an accurately modeled rotating file and differently shaped root canals during the clinical procedure was studied performing finite element analyses. Strains induced by the treatment on a file made of a “standard” Ni-Ti alloy (characterized by average properties of the pseudoelastic behavior), a “long” Ni-Ti alloy (characterized by wide transformation region), a “super” Ni-Ti alloy (characterized by an extended Hookian behavior without transformation region), and stainless steel were compared. The results accurately show the advantages of the use of Ni-Ti alloy with respect to stainless steel and the better performance of the “long” alloy in all the tested case.

  9. Structure characterization and wear performance of NiTi thermal sprayed coatings

    NASA Astrophysics Data System (ADS)

    Cinca, N.; Isalgué, A.; Fernández, J.; Guilemany, J. M.

    2010-08-01

    NiTi shape memory alloy (SMA) has been studied for many years for its shape memory and pseudoelastic properties, as well as its biocompatibility, which make it suitable for many biomedical applications. However, SMA NiTi is also interesting for relevant wear resistance near the transition temperature which, along with its high oxidation and corrosion resistance, suggests its use as a coating to increase the lifetime of some components. Also, whereas bulk material properties have been characterized in respect of the nominal composition, manufacturing methods and thermo-mechanical treatments, NiTi overlays have been investigated much less. Most existent works in this field specifically deal with magnetron sputtering technology for thin films and its use in micro-devices (micro-electro-mechanical systems, MEMS), just some works refer to vacuum plasma spraying (VPS) for thicker coatings. The present paper explores and compares the microstructure and wear-related properties of coatings obtained from atomized NiTi powders, by VPS as well as by atmospheric plasma spraying (APS) and high velocity oxygen fuel (HVOF) techniques. In the present case, the wear behaviour of the NiTi deposits has been studied by rubber-wheel equipment and ball-on-disk tests. The results obtained at room temperature show that the APS-quenched coatings exhibit a preferential dry sliding wear mechanism, while the VPS and HVOF coatings show an abrasive mechanism.

  10. Biomimetic Deposition of Apatite on Surface Chemically Modified Porous NiTi Shapememory Alloy

    NASA Astrophysics Data System (ADS)

    Wu, S. L.; Liu, X. M.; Chung, C. Y.; Chu, Paul K.; Chan, Y. L.; Yeung, K. W. K.; Chu, C. L.

    Porous NiTi shape memory alloy (SMA) with 48% porosity and an average pore size of 50-800 μm was synthesized by capsule-free hot isostatic pressing (CF-HIP). To enhance the surface bioactivity, the porous NiTi SMA was subjected to H2O2 and subsequent NaOH treatment. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses revealed that a porous sodium titanate (Na2TiO3) film had formed on the surface of the porous NiTi SMA. An apatite layer was deposited on this film after immersion in simulated body fluid at 37°C, while no apatite could be found on the surface of the untreated porous NiTi SMA. The formation of the apatite layer infers that the bioactivity of the porous NiTi SMA may be enhanced by surface chemical treatment, which is favorable for its application as bone implants.

  11. Creating poly(ethylene glycol) film on the surface of NiTi alloy by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Yu, Hongyan; Yan, Jin; Ma, Huiling; Zeng, Xinmiao; Liu, Yang; Zhao, Xinqing

    2015-07-01

    NiTi alloy has been extensively utilized as biomaterials owing to its unique shape memory effect, superelasticity and biocompatibility. However, concern with the toxic and allergic responses of nickel potentially releasing from implants stimulated lots of researches of modification on NiTi alloy surface. Creating chemical bond attachment of bioorganic film on NiTi alloy surface could effectively inhibit Ni releasing and obtain bioactive functions for further application. In this work, to get a bioorganic surface, NiTi alloy was modified with poly(ethylene glycol) (PEG) film by gamma ray induced grafting or crosslinking. X-ray diffraction (XRD) spectrum, water contact angle geometer and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize the NiTi surface. The results indicated that PEG was covalent bonded on NiTi alloy surface. Fluorescence microscope (FM) images for morphology of 1 day osteoblast culture on the PEG coated NiTi surface showed that PEG could improve cell proliferation on NiTi surface. Our work offers a way to introduce a bioorganic metal surface by gamma irradiation.

  12. A Comparative Study on the Mechanical Behavior of Porous Titanium and NiTi Produced by a Space Holder Technique

    NASA Astrophysics Data System (ADS)

    Hosseini, S. A.; Yazdani-Rad, R.; Kazemzadeh, A.; Alizadeh, M.

    2014-03-01

    NiTi and Ti porous specimens with appropriate pore characteristics for biomedical applications are produced by space holder method. Porosities of the specimens linearly increase from 14 to 65 and 42 to 70% for the Ti and NiTi specimens, respectively, with the urea space holder. Mechanical properties such as stiffness, fracture strain, and strength of the porous NiTi and Ti are adjustable with pore characteristics. The apparent elasticity modulus of NiTi specimens decrease from 3.5 to 0.73 GPa as porosity increases. Since the initial linear part of the stress-strain curve consists of elastic behavior, formation of stress-induced martensite, deformation and/or detwinning of martensite variants, and plastic deformation, the unloading slope of stress-strain curves is a better approximation for the elasticity modulus of the NiTi porous specimens as it is proved by an isotropic cubic cell model. The unloading slope of the NiTi specimen with 61% porosity is 3.1 GPa, while the apparent elasticity or loading slope is 0.85 GPa. In comparison to Ti, the high, recoverable strain of NiTi improves capability of it as a good candidate for bone replacement. Moreover, in contrast to Ti specimens, hysteresis loops are clearly observed in the stress-strain curves of NiTi specimens.

  13. Investigation of accelerated and natural carbonation of MSWI fly ash with a high content of Ca.

    PubMed

    Wang, Lei; Jin, Yiying; Nie, Yongfeng

    2010-02-15

    The application of accelerated carbonation and natural carbonation to treat municipal solid waste incinerator (MSWI) fly ash was presented. The influence of reaction time and the liquid-to-solid (L/S) ratio, which both affect the reactivity of CO(2), was evaluated to determine their impact on the quality of carbonation. The optimum carbonation reaction of fly ash was found to occur when an L/S of 0.25 was used. Carbonation decreased the leaching of Pb, Cu, Zn and As, but increased the leaching of Cd and Sb. Based on the leaching of these six heavy metals, the optimum pH of the carbonated fly ash was 9.5-10.5. The release of soluble salts such as SO(4), Cl and F changed little following carbonation, and their release occurred independently of pH. The release potential and leaching behavior of carbonated fly ash were further evaluated using the three-step sequential extraction procedure proposed by the commission of the European Communities Bureau of Reference (BCR). The results of the BCR analyses revealed that carbonation exerted a significant effect on the heavy metal fractions in steps 1 and 2, but little effect on the distribution of heavy metals in step 3 and residue fraction. Physical and chemical changes induced by carbonation were presented and discussed.

  14. Influence of Addition of Nb on Phase Transformation, Microstructure and Mechanical Properties of Equiatomic NiTi SMA

    NASA Astrophysics Data System (ADS)

    Jiang, Shuyong; Liang, Yulong; Zhang, Yanqiu; Zhao, Yanan; Zhao, Chengzhi

    2016-10-01

    Three novel NiTiNb shape memory alloys, which possess a nominal chemical composition of Ni50- x/2-Ti50- x/2-Nb x (at.%) where x stands for 2, 4 and 6, respectively, were designed in order to investigate the influence of the addition of Nb on phase transformation, microstructure and mechanical properties of equiatomic NiTi shape memory alloy. All the three NiTiNb shape memory alloys contain B2 austenite phase, B19' martensite phase and β-Nb precipitate phase. Martensite type II twin can be observed in the case of Ni49Ti49Nb2 alloy. In the case of Ni48Ti48Nb4 alloy, there exists a boundary between Ti2Ni precipitate phase and β-Nb precipitate phase. As for Ni47Ti47Nb6 alloy, it can be observed that there exists an orientation relationship of [01bar{1}]_{{β{{ - Nb}}}} //[01bar{1}]_{{B2}} between β-Nb precipitate phase and B2 austenite matrix. The increase in Nb content contributes to enhancing the yield stress of NiTiNb shape memory alloy, but it leads to the decrease in compression fracture stress. The addition of Nb to equiatomic NiTi shape memory alloy does not have a significant influence on the transformation hysteresis of the alloy, which is attributed to the fact that NiTiNb shape memory alloy is not subjected to plastic deformation and hence β-Nb precipitate phase is unable to relax the elastic strain in the martensite interface.

  15. Influence of Addition of Nb on Phase Transformation, Microstructure and Mechanical Properties of Equiatomic NiTi SMA

    NASA Astrophysics Data System (ADS)

    Jiang, Shuyong; Liang, Yulong; Zhang, Yanqiu; Zhao, Yanan; Zhao, Chengzhi

    2016-08-01

    Three novel NiTiNb shape memory alloys, which possess a nominal chemical composition of Ni50-x/2-Ti50-x/2-Nb x (at.%) where x stands for 2, 4 and 6, respectively, were designed in order to investigate the influence of the addition of Nb on phase transformation, microstructure and mechanical properties of equiatomic NiTi shape memory alloy. All the three NiTiNb shape memory alloys contain B2 austenite phase, B19' martensite phase and β-Nb precipitate phase. Martensite type II twin can be observed in the case of Ni49Ti49Nb2 alloy. In the case of Ni48Ti48Nb4 alloy, there exists a boundary between Ti2Ni precipitate phase and β-Nb precipitate phase. As for Ni47Ti47Nb6 alloy, it can be observed that there exists an orientation relationship of [01bar{1}]_{{β{{ - Nb}}}} //[01bar{1}]_{{B2}} between β-Nb precipitate phase and B2 austenite matrix. The increase in Nb content contributes to enhancing the yield stress of NiTiNb shape memory alloy, but it leads to the decrease in compression fracture stress. The addition of Nb to equiatomic NiTi shape memory alloy does not have a significant influence on the transformation hysteresis of the alloy, which is attributed to the fact that NiTiNb shape memory alloy is not subjected to plastic deformation and hence β-Nb precipitate phase is unable to relax the elastic strain in the martensite interface.

  16. Fabrication of hard coatings on NiTi instruments.

    PubMed

    Tripi, Teresa Roberta; Bonaccorso, Antonio; Condorelli, Guglielmo Guido

    2003-02-01

    The present study was designed to compare the nature of modified surface layers obtained by two different procedures on endodontic files made of NiTi alloy: the procedures were arc evaporation physical vapor deposition and thermal metal organic chemical vapor deposition (MOCVD). Experimental samples were GT Rotary Instruments. The first method was based on the physical deposition of elemental titanium in the presence of nitrogen. The second technique is a typical MOCVD procedure which adopts Ti(Et2N)4 as a titanium and nitrogen precursor. Control samples were not exposed to any process. The chemical composition of the surface and in-depth layers of each sample were examined by X-ray photoelectron spectroscopy and X-ray diffraction measurements. The instruments showed surface chemical compositions that were different from those seen in the control group; samples treated with the first method show a surface Nitrogen/Titanium ratio of 1; MOCVD instruments show a surface Nitrogen/Titanium ratio of 1.7; control samples show a Nitrogen/Titanium ratio of 0.2. Both techniques can produce a high nitrogen concentration on the surface. However, data showed that the morphologies, the in-depth nitrogen distribution, and the chemical nature of the coatings obtained with the two procedures were different. The paper also reports the effects of the two deposition procedures on the nickel/titanium ratio of the surface.

  17. Comparative Study of Clinically Used NiTi Orthodontic Wires

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Zhang, Yang; Hao, Fengyu; Yang, Ke; Tan, Lili

    The purpose of the study was to comparatively investigate two NiTi orthodontic wires. It is valuable to determine the phase transformation temperature and corrosion characteristics of the orthodontic wires to further study the shape memory effect and corrosion resistance properties. Optical microscope and EDX analysis were used for microstructure characteristics and composition analysis. Differential scanning calorimetry (DSC) was carried out to identify the phase transformation behavior of the two wires. Electrochemical tests in artificial saliva at 37 ±1°C including polarization and electrochemical impedance spectroscopy (EIS) were used to assess the corrosion resistance and corrosion mechanism of the wires. It was found that the transformation temperature range of A-wire (imported) is narrower while the As and Af are close to the body temperature, which is more suitable in the orthodontic operation at early stage. The corrosion current density of A-wire is lower than that of B-wire (domestically made) while the corrosion potential is higher. EIS test results indicated that the corrosion mechanism was the same. However, the oxide layer formed on the surface of A-wire is more protective.

  18. Variability in magnesium, carbon and oxygen isotope compositions, and trace element contents of brachiopod shells: implications for paleoceanographic studies

    NASA Astrophysics Data System (ADS)

    Rollion-Bard, Claire; Saulnier, Ségolène; Vigier, Nathalie; Schumacher, Aimryc; Chaussidon, Marc; Lécuyer, Christophe

    2016-04-01

    Magnesium content in the ocean is ≈ 1290 ppm and is one of the most abundant elements. It is involved in the carbon cycle via the dissolution and precipitation of carbonates, especially Mg-rich carbonates as dolomites. The Mg/Ca ratio of the ocean is believed to have changed through time. The causes of these variations, i.e. hydrothermal activity change or enhanced precipitation of dolomite, could be constrained using the magnesium isotope composition (δ26Mg) of carbonates. Brachiopods, as marine environmental proxies, have the advantage to occur worldwide in a depth range from intertidal to abyssal, and have been found in the geological record since the Cambrian. Moreover, as their shell is in low-Mg calcite, they are quite resistant to diagenetic processes. Here we report δ26Mg, δ18O, δ13C values along with trace element contents of one modern brachiopod specimen (Terebratalia transversa) and one fossil specimen (Terebratula scillae, 2.3 Ma). We combined δ26Mg values with oxygen and carbon isotope compositions and trace element contents to look for possible shell geochemical heterogeneities in order to investigate the processes that control the Mg isotope composition of brachiopod shells. We also evaluate the potential of brachiopods as a proxy of past seawater δ26Mg values. The two investigated brachiopod shells present the same range of δ26Mg variation (up to 2 ‰)). This variation cannot be ascribed to changes in environmental parameters, i.e. temperature or pH. As previously observed, the primary layer of calcite shows the largest degree of oxygen and carbon isotope disequilibrium relative to seawater. In contrast, the δ26Mg value of this layer is comparable to that of the secondary calcite layer value. In both T. scillae and T. transversa, negative trends are observable between magnesium isotopic compositions and oxygen and carbon isotopic compositions. These trends, combined to linear relationships between δ26Mg values and REE contents, are best

  19. A Sustainable Route from Biomass Byproduct Okara to High Content Nitrogen-Doped Carbon Sheets for Efficient Sodium Ion Batteries.

    PubMed

    Yang, Tingzhou; Qian, Tao; Wang, Mengfan; Shen, Xiaowei; Xu, Na; Sun, Zhouzhou; Yan, Chenglin

    2016-01-20

    A sustainable route from the biomass byproduct okara as a natural nitrogen fertilizer to high-content N-doped carbon sheets is demonstrated. The as-prepared unique structure exhibits high specific capacity (292 mAh g(-1) ) and extremely long cycle life (exceeding 2000 cycles). A full battery is devised for the practical use of materials with a flexible/wearable LED screen.

  20. A regional estimate of soil organic carbon content linking the RothC model to spatialised climate and soil database

    NASA Astrophysics Data System (ADS)

    Sirca, Costantino; Salis, Michele; Spano, Donatella

    2014-05-01

    Soil organic carbon (SOC) represents the largest pool of organic carbon in the biosphere, and plays a vital role in ecosystem function determining soil fertility, water holding capacity, and susceptibility to land degradation. The SOC amount is mainly led by soil type, land use, and climate. In this work an assessment of SOC pools in Mediterranean soils is presented. The SOC content was estimated at regional scale in Sardinia, the second largest island of the Mediterranean Basin, linking the RothC model (Rothamsted Carbon model) to a high detailed spatialised climate, land use and soil database. More than 300 soil analysis data, covering different land use typologies, were used for the calibration and validation of the model. A good agreement between soil C estimated from the model and ground data was found. The methodology allowed to obtain the current SOC pools estimation for the different land use categories at regional scale.

  1. Quantitative Analysis of Carbon Content in Bituminous Coal by Laser-Induced Breakdown Spectroscopy Using UV Laser Radiation

    NASA Astrophysics Data System (ADS)

    Li, Xiongwei; Mao, Xianglei; Wang, Zhe; Richard, E. Russo

    2015-11-01

    The carbon content of bituminous coal samples was analyzed by laser-induced breakdown spectroscopy. The 266 nm laser radiation was utilized for laser ablation and plasma generation in air. The partial least square method and the dominant factor based PLS method were used to improve the measurement accuracy of the carbon content of coal. The results showed that the PLS model could achieve good measurement accuracy, and the dominant factor based PLS model could further improve the measurement accuracy. The coefficient of determination and the root-mean-square error of prediction of the PLS model were 0.97 and 2.19%, respectively; and those values for the dominant factor based PLS model were 0.99 and 1.51%, respectively. The results demonstrated that the 266 nm wavelength could accurately measure the carbon content of bituminous coal. supported by National Natural Science Foundation of China (No. 51276100) and the National Basic Research Program of China (973 Program) (No. 2013CB228501). The authors also thank the financial funding from the U. S. Department of Energy, Office of Basic Energy Sciences, Chemical Science Division at Lawrence Berkeley National Laboratory (No. 2013CB228501)

  2. Effects of Retained Austenite Volume Fraction, Morphology, and Carbon Content on Strength and Ductility of Nanostructured TRIP-assisted Steels

    SciTech Connect

    Shen, Yongfeng; Qiu, LN; Sun, Xin; Zuo, Liang; Liaw, Peter K.; Raabe, Dierk

    2015-06-01

    With a suite of multi-modal and multi-scale characterization techniques, the present study unambiguously proves that a substantially-improved combination of ultrahigh strength and good ductility can be achieved by tailoring the volume fraction, morphology, and carbon content of the retained austenite (RA) in a transformation-induced-plasticity (TRIP) steel with the nominal chemical composition of 0.19C-0.30Si-1.76Mn-1.52Al (weight percent, wt.%). After intercritical annealing and bainitic holding, a combination ultimate tensile strength (UTS) of 1,100 MPa and true strain of 50% has been obtained, as a result of the ultrafine RA lamellae, which are alternately arranged in the bainitic ferrite around junction regions of ferrite grains. For reference, specimens with a blocky RA, prepared without the bainitic holding, yield a low ductility (35%) and a low UTS (800 MPa). The volume fraction, morphology, and carbon content of RA have been characterized using various techniques, including magnetic probing, scanning electron microscopy (SEM), electron-backscatter-diffraction (EBSD), and transmission electron microscopy (TEM). Interrupted tensile tests, mapped using EBSD in conjunction with the kernel average misorientation (KAM) analysis, reveal that the lamellar RA is the governingmicrostructure component responsible for the higher mechanical stability, compared to the blocky one. By coupling these various techniques, we quantitatively demonstrate that in addition to the RA volume fraction, its morphology and carbon content are equally important in optimizing the strength and ductility of TRIP-assisted steels.

  3. Higher peroxidase activity, leaf nutrient contents and carbon isotope composition changes in Arabidopsis thaliana are related to rutin stress.

    PubMed

    Hussain, M Iftikhar; Reigosa, Manuel J

    2014-09-15

    Rutin, a plant secondary metabolite that is used in cosmetics and food additive and has known medicinal properties, protects plants from UV-B radiation and diseases. Rutin has been suggested to have potential in weed management, but its mode of action at physiological level is unknown. Here, we report the biochemical, physiological and oxidative response of Arabidopsis thaliana to rutin at micromolar concentrations. It was found that fresh weight; leaf mineral contents (nitrogen, sodium, potassium, copper and aluminum) were decreased following 1 week exposure to rutin. Arabidopsis roots generate significant amounts of reactive oxygen species after rutin treatment, consequently increasing membrane lipid peroxidation, decreasing leaf Ca(2+), Mg(2+), Zn(2+), Fe(2+) contents and losing root viability. Carbon isotope composition in A. thaliana leaves was less negative after rutin application than the control. Carbon isotope discrimination values were decreased following rutin treatment, with the highest reduction compared to the control at 750μM rutin. Rutin also inhibited the ratio of CO2 from leaf to air (ci/ca) at all concentrations. Total protein contents in A. thaliana leaves were decreased following rutin treatment. It was concluded carbon isotope discrimination coincided with protein degradation, increase lipid peroxidation and a decrease in ci/ca values may be the primary action site of rutin. The present results suggest that rutin possesses allelopathic potential and could be used as a candidate to develop environment friendly natural herbicide.

  4. Revision of Fontes & Garnier's model for the initial 14C content of dissolved inorganic carbon used in groundwater dating

    USGS Publications Warehouse

    Han, Liang-Feng; Plummer, L. Niel

    2013-01-01

    The widely applied model for groundwater dating using 14C proposed by Fontes and Garnier (F&G) (Fontes and Garnier, 1979) estimates the initial 14C content in waters from carbonate-rock aquifers affected by isotopic exchange. Usually, the model of F&G is applied in one of two ways: (1) using a single 13C fractionation factor of gaseous CO2 with respect to a solid carbonate mineral, εg/s, regardless of whether the carbon isotopic exchange is controlled by soil CO2 in the unsaturated zone, or by solid carbonate mineral in the saturated zone; or (2) using different fractionation factors if the exchange process is dominated by soil CO2 gas as opposed to solid carbonate mineral (typically calcite). An analysis of the F&G model shows an inadequate conceptualization, resulting in underestimation of the initial 14C values (14C0) for groundwater systems that have undergone isotopic exchange. The degree to which the 14C0 is underestimated increases with the extent of isotopic exchange. Examples show that in extreme cases, the error in calculated adjusted initial 14C values can be more than 20% modern carbon (pmc). A model is derived that revises the mass balance method of F&G by using a modified model conceptualization. The derivation yields a “global” model both for carbon isotopic exchange dominated by gaseous CO2 in the unsaturated zone, and for carbon isotopic exchange dominated by solid carbonate mineral in the saturated zone. However, the revised model requires different parameters for exchange dominated by gaseous CO2 as opposed to exchange dominated by solid carbonate minerals. The revised model for exchange dominated by gaseous CO2 is shown to be identical to the model of Mook (Mook, 1976). For groundwater systems where exchange occurs both in the unsaturated zone and saturated zone, the revised model can still be used; however, 14C0 will be slightly underestimated. Finally, in carbonate systems undergoing complex geochemical reactions, such as oxidation of

  5. Effects of Carbon Content on the Electrochemical Performances of MoS2-C Nanocomposites for Li-Ion Batteries.

    PubMed

    Sun, Weiyi; Hu, Zhe; Wang, Caiyun; Tao, Zhanliang; Chou, Shu-Lei; Kang, Yong-Mook; Liu, Hua-Kun

    2016-08-31

    Molybdenum disulfide is popular for rechargeable batteries, especially in Li-ion batteries, because of its layered structure and relatively high specific capacity. In this paper, we report MoS2-C nanocomposites that are synthesized by a hydrothermal process, and their use as anode material for Li-ion batteries. Ascorbic acid is used as the carbon source, and the carbon contents can be tuned from 2.5 wt % to 16.2 wt %. With increasing of carbon content, the morphology of MoS2-C nanocomposites changes from nanoflowers to nanospheres, and the particle size is decreased from 200 to 60 nm. This change is caused by the chemical complex interaction of ascorbic acid. The MoS2-C nanocomposite with 8.4 wt % C features a high capacity of 970 mAh g(-1) and sustains a capacity retention ratio of nearly 100% after 100 cycles. When the current increases to 1000 mA g(-1), the capacity still reaches 730 mAh g(-1). The above manifests that the carbon coating layer does not only accelerate the charge transfer kinetics to supply quick discharging and charging, but also hold the integrity of the electrode materials as evidenced by the long cycling stability. Therefore, MoS2-based nanocomposites could be used as commercial anode materials in Li-ion batteries. PMID:27502442

  6. Effects of Carbon Content on the Electrochemical Performances of MoS2-C Nanocomposites for Li-Ion Batteries.

    PubMed

    Sun, Weiyi; Hu, Zhe; Wang, Caiyun; Tao, Zhanliang; Chou, Shu-Lei; Kang, Yong-Mook; Liu, Hua-Kun

    2016-08-31

    Molybdenum disulfide is popular for rechargeable batteries, especially in Li-ion batteries, because of its layered structure and relatively high specific capacity. In this paper, we report MoS2-C nanocomposites that are synthesized by a hydrothermal process, and their use as anode material for Li-ion batteries. Ascorbic acid is used as the carbon source, and the carbon contents can be tuned from 2.5 wt % to 16.2 wt %. With increasing of carbon content, the morphology of MoS2-C nanocomposites changes from nanoflowers to nanospheres, and the particle size is decreased from 200 to 60 nm. This change is caused by the chemical complex interaction of ascorbic acid. The MoS2-C nanocomposite with 8.4 wt % C features a high capacity of 970 mAh g(-1) and sustains a capacity retention ratio of nearly 100% after 100 cycles. When the current increases to 1000 mA g(-1), the capacity still reaches 730 mAh g(-1). The above manifests that the carbon coating layer does not only accelerate the charge transfer kinetics to supply quick discharging and charging, but also hold the integrity of the electrode materials as evidenced by the long cycling stability. Therefore, MoS2-based nanocomposites could be used as commercial anode materials in Li-ion batteries.

  7. Sulfur contents of peats at the confluence of carbonate and peat-forming depositional systems, southeastern Florida

    SciTech Connect

    Cohen, A.D. ); Davies, T.D. ); Spackman, W. )

    1993-08-01

    Complex stratigraphic and compositional relationships have been reported by others at sites where coal beds are laterally in contact with marine carbonates (such as in the southern portion of the Illinois basin). These basin edges are important in that they may (1) represent sites of active coal mining, (2) contain important clues as to the development of the basin, and (3) be sources of the dispersed terrestrial organics encountered in nearby marine rocks. This study was undertaken to investigate peat/carbonate relationships in a modern setting, with initial research on sulfur contents relative to stratigraphic/petrographic conditions. Thirty-eight cores were taken along northwest-southeast transects from the mainland to Florida Bay. The most inland cores consist entirely of peat, representing transgression of marine types (mangrove) over freshwater types. Toward the carbonate-rich bay, a more complex stratigraphy exists. Marine carbonates and peats interfinger, with erosional contacts indicating that parts of the peat sequence are missing. At the coastline, most of the peat is replaced by marine carbonate except for thin (1-10 cm) basal (usually overlain by marine carbonates), with the best preserved ranges from 0.6 to 5.0% (dry) at the most inland sites, 2.4 to 7.8% near the coastline, and 1.5 to 5.9% in bay sediments. Total sulfur is higher in marine than freshwater peats, but freshwater peats overlain by marine peats are enriched in sulfur. Freshwater peats beneath marine carbonates are relatively low in sulfur, but are higher if the peat is overlain by a marine peat before being overlain by the carbonate.

  8. Surface corrosion enhancement of passive films on NiTi shape memory alloy in different solutions.

    PubMed

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

    2016-06-01

    The corrosion behaviors of NiTi shape memory alloy in NaCl solution, H2SO4 solution and borate buffer solution were investigated. It was found that TiO2 in passive film improved the corrosion resistance of NiTi shape memory. However, low corrosion resistance of passive film was observed in low pH value acidic solution due to TiO2 dissolution. Moreover, the corrosion resistance of NiTi shape memory alloy decreased with the increasing of passivated potential in the three solutions. The donor density in passive film increased with the increasing of passivated potential. Different solutions affect the semiconductor characteristics of the passive film. The reducing in the corrosion resistance was attributed to the more donor concentrations in passive film and thinner thickness of the passive film.

  9. Fatigue properties of NiTi shape-memory alloy thin plates

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hiroshi; Taya, Minoru; Liang, Yuanchang; Namli, Onur C.; Saito, Makoto

    2013-04-01

    The mechanical and fatigue characteristics of superelastic NiTi thin plates in the large strain area were obtained by tensile and pulsating 4-point bending tests to establish the design guidelines for the ferromagnetic shape memory alloy (FSMA) composite actuator and its fatigue life. The stress-strain curves of NiTi thin plates were found to be strain rate dependent. The finite element analysis (FEA) result using the stress-strain curve measured by tensile test is in good agreement with the experimental results of the 4-point bending tests. The relationship between the maximum bending strain and the number of cycles to failure in pulsating 4-point bending fatigue tests was obtained as well as an analysis of the fatigue fracture surfaces of NiTi thin plates.

  10. Molecular dynamics study of the melting curve of NiTi alloy under pressure

    NASA Astrophysics Data System (ADS)

    Zeng, Zhao-Yi; Hu, Cui-E.; Cai, Ling-Cang; Chen, Xiang-Rong; Jing, Fu-Qian

    2011-02-01

    The melting curve of NiTi alloy was predicted by using molecular dynamics simulations combining with the embedded atom model potential. The calculated thermal equation of state consists well with our previous results obtained from quasiharmonic Debye approximation. Fitting the well-known Simon form to our Tm data yields the melting curves for NiTi: 1850(1 + P/21.938)0.328 (for one-phase method) and 1575(1 + P/7.476)0.305 (for two-phase method). The two-phase simulations can effectively eliminate the superheating in one-phase simulations. At 1 bar, the melting temperature of NiTi is 1575 ± 25 K and the corresponding melting slope is 64 K/GPa.

  11. Photofabrication of the third dimension of NiTi shape memory alloy microactuators

    NASA Astrophysics Data System (ADS)

    Allen, David M.; Leong, Tony; Lim, Siang H.; Kohl, Manfred

    1997-09-01

    This paper describes experimental results of using various microlithography techniques to fabricate a range of microactuator devices from NiTi shape memory alloys. The range of products includes: planar double-beams form rolled foils etched form both sides; tapered double-beams; planar double beams from sputter-deposited films etched rom one side; a tubular test piece. Such photofabrication in not easily achieved and problems discussed in this paper include: achieving acceptable edge profiles through the thickness of the materials while maintaining high etch factors; tapering foil microactuators by means of chemical micro milling; coating NiTi tubes with electrophoretic photoresist; imaging a curved surface with a small radius of curvature; control of etching parameters for a constant rate of etch; the influence of NiTi oxide coatings on etching and; technical comparisons with other potential manufacturing processes.

  12. Experimental Investigation on the Mechanical Instability of Superelastic NiTi Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Xiao, Yao; Zeng, Pan; Lei, Liping

    2016-09-01

    In this paper, primary attention is paid to the mechanical instability of superelastic NiTi shape memory alloy (SMA) during localized forward transformation at different temperatures. By inhibiting the localized phase transformation, we can obtain the up-down-up mechanical response of NiTi SMA, which is closely related to the intrinsic material softening during localized martensitic transformation. Furthermore, the material parameters of the up-down-up stress-strain curve are extracted, in such a way that this database can be utilized for simulation and validation of the theoretical analysis. It is found that during forward transformation, the upper yield stress, lower yield stress, Maxwell stress, and nucleation stress of NiTi SMA exhibit linear dependence on temperature. The relation between nucleation stress and temperature can be explained by the famous Clausius-Clapeyron equation, while the relation between upper/lower yield stress and temperature lacks theoretical study, which needs further investigation.

  13. Wear Properties of Porous NiTi Orthopedic Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Wu, Shuilin; Liu, Xiangmei; Yeung, K. W. K.; Xu, Z. S.; Chung, C. Y.; Chu, Paul K.

    2012-12-01

    Porous NiTi shape memory alloy (SMA) scaffolds have great potential to be used as orthopedic implants because of their porous structure and superior physical properties. Its metallic nature provides it with better mechanical properties and Young's modulus close to that of natural bones. Besides allowing tissue ingrowth and transfer of nutrients, porous SMA possesses unique pseudoelastic properties compatible to natural hard tissues like bones and tendons, thus expediting in vivo osseointegration. However, the nickel release from debris and the metal surface may cause osteocytic osteolysis at the interface between the artificial implants and bone tissues. Subsequent mobilization may finally lead to implant failure. In this study, the wear properties of porous NiTi with different porosities processed at different treatment temperatures are determined. The results of the study show that the porosity, phase transformation temperature, and annealing temperature are major factors influencing the wear characteristics of porous NiTi SMA.

  14. Anomalous expansion of Nb nanowires in a NiTi matrix under high pressure

    NASA Astrophysics Data System (ADS)

    Yu, Cun; Ren, Yang; Cui, Lishan; Ma, Zhiyuan; Yang, Wenge

    2016-10-01

    Under high pressure, materials usually shrink during compression as described by an equation of state. Here, we present the anomalous volume expansion behavior of a one-dimensional Nb nano-wire embedded in a NiTi transforming matrix, while the matrix undergoes a pressure-induced martensitic transformation. The Nb volume expansion depends on the NiTi transition pressure range from the matrix, which is controlled by the shear strain induced by different pressure transmitting media. The transformation-induced interfacial stresses between Nb and NiTi may play a major role in this anomaly. Our discovery sheds new light on the nano-interfacial effect on mechanical anomalies in heterogeneous systems during a pressure-induced phase transition.

  15. Advanced in-situ measurement of soil carbon content using inelastic neutron scattering

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measurement and mapping of natural and anthropogenic variations in soil carbon stores is a critical component of any soil resource evaluation process. Emerging modalities for soil carbon analysis in the field is the registration of gamma rays from soil under neutron irradiation. The inelastic neutro...

  16. Cavitation erosion resistance of two steels with the same percentage of Chromium and Nickel but different Carbon content

    NASA Astrophysics Data System (ADS)

    Bordeasu, I.; Popoviciu, M. O.; Mitelea, I.; Ghiban, B.; Ghiban, N.

    2014-03-01

    Hydraulic machinery repair works necessitate new materials with improved cavitation erosion resistance and simultaneously good welding properties. The present paper is concerned with the behavior at cavitation of two steels with close contents of chromium (approximately 12%) and nickel (approximate 6%) but with different carbon content (for the first 0.1% C and the second 0.036% C). The reduced carbon content is necessary for an easy welding repair work. As a result of the different chemical content, as is shown by the Schäffler diagram, the steel containing 0.1% C has a structure formed by 60% austenite and 40% martensite while those with 0.036% C has completely martensitic structure. The laboratory tests were done in two vibratory devices one with piezoelectric crystals, respecting the ASME G32-2010 Standard and the other a magnetostrictive vibratory device with nickel tube. The evaluation of the cavitation resistance was obtained with the help of cavitation erosion characteristic curves MDE (t) and MDER (t). For analyzing the steel degradation, the eroded areas were also subjected to microscopic investigations. The results show that the steel with 0.1% C has better cavitation erosion behavior than that of the steel with 0.036% C.

  17. Constitutive model for the dynamic response of a NiTi shape memory alloy

    NASA Astrophysics Data System (ADS)

    Shi, Xiaohong; Zeng, Xiangguo; Chen, Huayan

    2016-07-01

    In this paper, based on irreversible thermodynamic theory, the Helmholtz free energy function, was selected to deduce both the master equations and evolution equations of the constitutive model of a NiTi alloy under high strain. The Helmholtz free energy function contains the parameters of the reflecting phase transition and plastic property. The constitutive model for a NiTi alloy was implemented using a semi-implicit stress integration algorithm. Four successive stages can be differentiated and simulated: parent phase elasticity, martensitic phase transition, martensitic elasticity, and dislocation yield. The simulation results are in good agreement with the experimental results.

  18. Enhancement of NiTi superelastic endodontic instruments by TiO2 coating.

    PubMed

    Aun, Diego Pinheiro; Peixoto, Isabella Faria da Cunha; Houmard, Manuel; Buono, Vicente Tadeu Lopes

    2016-11-01

    Rotary nickel-titanium (NiTi) endodontic instruments were coated with a nanometric flexible TiO2 layer through dip-coating sol-gel. Control groups and coated samples of superelastic NiTi instruments model RaCe 25/0.06 (0.25mm tip-diameter, 6% conicity) were comparatively investigated with respect to the cutting efficiency, fatigue life, and corrosion resistance. Results showed an improvement in cutting efficiency for the coated samples and a high resistance to corrosion in NaClO. The coated instruments showed a better performance in fatigue life after corrosion.

  19. Corrosion resistance of porous NiTi biomedical alloy in simulated body fluids

    NASA Astrophysics Data System (ADS)

    Stergioudi, F.; Vogiatzis, C. A.; Pavlidou, E.; Skolianos, S.; Michailidis, N.

    2016-09-01

    The corrosion performance of two porous NiTi in physiological and Hank’s solutions was investigated by potentiodynamic polarization, cyclic polarization and impedance spectroscopy. Electric models simulating the corrosion mechanism at early stages of immersion were proposed, accounting for both microstructural observations and electrochemical results. Results indicate that both porous samples were susceptible to localized corrosion. The porosity increase (from 7% to 18%) resulted in larger and wider pore openings, thus favoring the corrosion resistance of 18% porous NiTi. Strengthening of corrosion resistance was observed in Hank’s solution. The pore morphology and micro-galvanic corrosion phenomena were determining factors affecting the corrosion resistance.

  20. Enhancement of NiTi superelastic endodontic instruments by TiO2 coating.

    PubMed

    Aun, Diego Pinheiro; Peixoto, Isabella Faria da Cunha; Houmard, Manuel; Buono, Vicente Tadeu Lopes

    2016-11-01

    Rotary nickel-titanium (NiTi) endodontic instruments were coated with a nanometric flexible TiO2 layer through dip-coating sol-gel. Control groups and coated samples of superelastic NiTi instruments model RaCe 25/0.06 (0.25mm tip-diameter, 6% conicity) were comparatively investigated with respect to the cutting efficiency, fatigue life, and corrosion resistance. Results showed an improvement in cutting efficiency for the coated samples and a high resistance to corrosion in NaClO. The coated instruments showed a better performance in fatigue life after corrosion. PMID:27524067

  1. An adjustment in NiTi closed coil spring for an extended range of activation.

    PubMed

    Ravipati, Raghu Ram; Sivakumar, Arunachalam; Sudhakar, P; Padmapriya, C V; Bhaskar, Mummudi; Azharuddin, Mohammad

    2014-01-01

    The Nickel Titanium (NiTi) closed coil springs serve as an efficient force delivery system in orthodontic space closure mechanics. The closed coil springs with the eyelets come in various lengths to broaden its force characteristics for an expedient space closure. However, at a certain point of time of progressive space closure, the coil spring can be expanded no further for an adequate force delivery. In such situations, the clinician prefers to replace the existing spring with another short length spring. The present article describes a simple conservative technique for progressively re-activating the same NiTi closed coil spring for complete space closure.

  2. Social Network and Content Analysis of the North American Carbon Program as a Scientific Community of Practice

    NASA Technical Reports Server (NTRS)

    Brown, Molly E.; Ihli, Monica; Hendrick, Oscar; Delgado-Arias, Sabrina; Escobar, Vanessa M.; Griffith, Peter

    2015-01-01

    The North American Carbon Program (NACP) was formed to further the scientific understanding of sources, sinks, and stocks of carbon in Earth's environment. Carbon cycle science integrates multidisciplinary research, providing decision-support information for managing climate and carbon-related change across multiple sectors of society. This investigation uses the conceptual framework of com-munities of practice (CoP) to explore the role that the NACP has played in connecting researchers into a carbon cycle knowledge network, and in enabling them to conduct physical science that includes ideas from social science. A CoP describes the communities formed when people consistently engage in shared communication and activities toward a common passion or learning goal. We apply the CoP model by using keyword analysis of abstracts from scientific publications to analyze the research outputs of the NACP in terms of its knowledge domain. We also construct a co-authorship network from the publications of core NACP members, describe the structure and social pathways within the community. Results of the content analysis indicate that the NACP community of practice has substantially expanded its research on human and social impacts on the carbon cycle, contributing to a better understanding of how human and physical processes interact with one another. Results of the co-authorship social network analysis demonstrate that the NACP has formed a tightly connected community with many social pathways through which knowledge may flow, and that it has also expanded its network of institutions involved in carbon cycle research over the past seven years.

  3. A Raman Study of Carbonates and Organic Contents in Five CM Chondrites

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.; Bodnar, R. J.; Farley, C.; Cheung, J. C. H.

    2016-01-01

    Carbonates comprise the second most abundant class of carbon-bearing phases in carbonaceous chondrites after organic matter (approximately 2 wt.%), followed by other C-bearing phases such as diamond, silicon carbide, and graphite. Therefore, understanding the abundances of carbonates and the associated organic matter provide critical insight into the genesis of major carbonaceous components in chondritic materials. Carbonates in CM chondrites mostly occur as calcite (of varying composition) and dolomite. Properly performed, Raman spectroscopy provides a non-destructive technique for characterizing meteorite mineralogy and organic chemistry. It is sensitive to many carbonaceous phases, allows the differentiation of organic from inorganic materials, and the interpretation of their spatial distribution. Here, with the use of Raman spectroscopy, we determine the structure of the insoluble organic matter (IOM) in the matrix and carbonate phases in five CM chondrites: Jbilet Winselwan, Murchison, Nogoya, Santa Cruz, and Wisconsin Range (WIS) 91600, and interpret the relative timing of carbonate precipitation and the extent of the associated alteration events.

  4. Soil carbon dioxide emission and carbon content as affected by irrigation, tillage, cropping system, and nitrogen fertilization.

    PubMed

    Sainju, Upendra M; Jabro, Jalal D; Stevens, William B

    2008-01-01

    Management practices can influence soil CO(2) emission and C content in cropland, which can effect global warming. We examined the effects of combinations of irrigation, tillage, cropping systems, and N fertilization on soil CO(2) flux, temperature, water, and C content at the 0- to 20-cm depth from May to November 2005 at two sites in the northern Great Plains. Treatments were two irrigation systems (irrigated vs. non-irrigated) and six management practices that contained tilled and no-tilled malt barley (Hordeum vulgaris L.) with 0 to 134 kg N ha(-1), no-tilled pea (Pisum sativum L.), and a conservation reserve program (CRP) planting applied in Lihen sandy loam (sandy, mixed, frigid, Entic Haplustolls) in western North Dakota. In eastern Montana, treatments were no-tilled malt barley with 78 kg N ha(-1), no-tilled rye (Secale cereale L.), no-tilled Austrian winter pea, no-tilled fallow, and tilled fallow applied in dryland Williams loam (fine-loamy, mixed Typic Argiborolls). Irrigation increased CO(2) flux by 13% compared with non-irrigation by increasing soil water content in North Dakota. Tillage increased CO(2) flux by 62 to 118% compared with no-tillage at both places. The flux was 1.5- to 2.5-fold greater with tilled than with non-tilled treatments following heavy rain or irrigation in North Dakota and 1.5- to 2.0-fold greater with crops than with fallow following substantial rain in Montana. Nitrogen fertilization increased CO(2) flux by 14% compared with no N fertilization in North Dakota and cropping increased the flux by 79% compared with fallow in no-till and 0 kg N ha(-1) in Montana. The CO(2) flux in undisturbed CRP was similar to that in no-tilled crops. Although soil C content was not altered, management practices influenced CO(2) flux within a short period due to changes in soil temperature, water, and nutrient contents. Regardless of irrigation, CO(2) flux can be reduced from croplands to a level similar to that in CRP planting using no

  5. Effects of oxygen and carbon content on nitrogen removal capacities in landfill bioreactors and response of microbial dynamics.

    PubMed

    Xu, Weiqing; Wu, Dong; Wang, Jie; Huang, Xinghua; Xie, Bing

    2016-07-01

    In this study, landfill bioreactors were tested to treat the recalcitrant leachate-nitrogen and the impacts of relevant operational parameters on its conversion were comprehensively investigated. We found that the highly diverse microbial community in landfill bioreactors could be substantially affected by increasing biodegradable carbon and oxygen content, which led to the whole system's intrinsic nitrogen removal capacity increasing from 50 to 70 %, and meanwhile, the contribution of anammox was detected less than 20 %. The sequencing and q-PCR results showed that microbial community in bioreactor was dominated by Proteobacteria (∼35 %) and Acidobacteria (~20 %) during the whole experiment. The abundance of anammox functioning bacteria (Amx) kept at a stable level (-2.5 to -2.2 log (copies/16S rRNA)) and was not statistically correlated to the abundance of anammox bacteria. However, significant linear correlation (p < 0.05) was determined between the abundance of nirS and Proteobacteria; amoA and AOB. Redundancy analysis (RDA) suggested that although oxygen and biodegradable carbon can both impose effects on microbial community structure, only biodegradable carbon content is the determinant in the total nitrogen removal. PMID:27005414

  6. Transient tracer distributions in the Fram Strait in 2012 and inferred anthropogenic carbon content and transport

    NASA Astrophysics Data System (ADS)

    Stöven, Tim; Tanhua, Toste; Hoppema, Mario; von Appen, Wilken-Jon

    2016-02-01

    The storage of anthropogenic carbon in the ocean's interior is an important process which modulates the increasing carbon dioxide concentrations in the atmosphere. The polar regions are expected to be net sinks for anthropogenic carbon. Transport estimates of dissolved inorganic carbon and the anthropogenic offset can thus provide information about the magnitude of the corresponding storage processes. Here we present a transient tracer, dissolved inorganic carbon (DIC) and total alkalinity (TA) data set along 78°50' N sampled in the Fram Strait in 2012. A theory on tracer relationships is introduced, which allows for an application of the inverse-Gaussian-transit-time distribution (IG-TTD) at high latitudes and the estimation of anthropogenic carbon concentrations. Mean current velocity measurements along the same section from 2002-2010 were used to estimate the net flux of DIC and anthropogenic carbon by the boundary currents above 840 m through the Fram Strait. The new theory explains the differences between the theoretical (IG-TTD-based) tracer age relationship and the specific tracer age relationship of the field data, by saturation effects during water mass formation and/or the deliberate release experiment of SF6 in the Greenland Sea in 1996, rather than by different mixing or ventilation processes. Based on this assumption, a maximum SF6 excess of 0.5-0.8 fmol kg-1 was determined in the Fram Strait at intermediate depths (500-1600 m). The anthropogenic carbon concentrations are 50-55 µmol kg-1 in the Atlantic Water/Recirculating Atlantic Water, 40-45 µmol kg-1 in the Polar Surface Water/warm Polar Surface Water and between 10 and 35 µmol kg-1 in the deeper water layers, with lowest concentrations in the bottom layer. The net fluxes through the Fram Strait indicate a net outflow of ˜ 0.4 DIC and ˜ 0.01 PgC yr-1 anthropogenic carbon from the Arctic Ocean into the North Atlantic, albeit with high uncertainties.

  7. Concentration and 14C Content of Total Organic Carbon and Black Carbon in Small (<100 ug C) Samples from Low-Latitude Alpine Ice Cores

    NASA Astrophysics Data System (ADS)

    Kehrwald, N. M.; Czimczik, C. I.; Santos, G. M.; Thompson, L. G.; Ziolkowski, L.

    2008-12-01

    Many low latitude glaciers are receding with consequences for the regional energy budget and hydrology. Ice loss has been linked to climate change and the deposition of organic aerosols such as black carbon (BC) which is formed during incomplete combustion. Little is known about how the contents of BC and total organic carbon (TOC) in aerosols change over time and how anthropogenic activities (e.g. land-use change) impact this variability. Low-latitude ice cores are located closer to population centers than polar ice caps and can provide a regional synthesis of TOC and BC variability. Radiocarbon (14C) may be used to partition BC aerosols into fossil (>50 kyrs) and modern sources (e.g. fossil-fuels vs. wildfires). We quantified TOC, BC, and their 14C content in three low-latitude ice cores: Naimona'nyi (30°27'N, 81°91'E) and Dasuopu (28°23'N, 85°43'E), Tibet, and Quelccaya (13°56'S; 70°50'W), Peru. Aerosols (52-256 g ice on filters) were separated into TOC and BC using thermal oxidation (CTO- 375). 14C was measured by AMS. TOC contents were 0.11-0.87, 0.05-0.43, and 0.06-0.19 μg C (g ice) -1 for Naimona'nyi, Dasuopu, and Quelccaya, respectively. BC contents were 18±8, 27±4, and 29±12 %TOC. Procedural blanks were 0.8 ± 0.4 μg C (TOC) and 1.2 ± 0.6 μg C (BC). In ice cores well dated through annual layer counting and/or independent ages (e.g. volcanic horizons) such as Quelccaya, the ability to separate BC from TOC, as well as partition BC into fossil and modern contributions has potential for reconstructing pre- and post-industrial changes in aerosol composition and their impact on the energy budget.

  8. Influence of Carbonic Anhydrase Activity in Terrestrial Vegetation on the 18O Content of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Gillon, Jim; Yakir, Dan

    2001-03-01

    The oxygen-18 (18O) content of atmospheric carbon dioxide (CO2) is an important indicator of CO2 uptake on land. It has generally been assumed that during photosynthesis, oxygen in CO2 reaches isotopic equilibrium with oxygen in 18O-enriched water in leaves. We show, however, large differences in the activity of carbonic anhydrase (which catalyzes CO2 hydration and 18O exchange in leaves) among major plant groups that cause variations in the extent of 18O equilibrium (θeq). A clear distinction in θeq between C3 trees and shrubs, and C4 grasses makes atmospheric C18OO a potentially sensitive indicator to changes in C3 and C4 productivity. We estimate a global mean θeq value of ~0.8, which reasonably reconciles inconsistencies between 18O budgets of atmospheric O2 (Dole effect) and CO2.

  9. Prediction of moisture, calorific value, ash and carbon content of two dedicated bioenergy crops using near-infrared spectroscopy.

    PubMed

    Fagan, Colette C; Everard, Colm D; McDonnell, Kevin

    2011-04-01

    The potential of near infrared spectroscopy in conjunction with partial least squares regression to predict Miscanthus xgiganteus and short rotation coppice willow quality indices was examined. Moisture, calorific value, ash and carbon content were predicted with a root mean square error of cross validation of 0.90% (R(2) = 0.99), 0.13 MJ/kg (R(2) = 0.99), 0.42% (R(2) = 0.58), and 0.57% (R(2) = 0.88), respectively. The moisture and calorific value prediction models had excellent accuracy while the carbon and ash models were fair and poor, respectively. The results indicate that near infrared spectroscopy has the potential to predict quality indices of dedicated energy crops, however the models must be further validated on a wider range of samples prior to implementation. The utilization of such models would assist in the optimal use of the feedstock based on its biomass properties.

  10. Effect of Deformation Mode on the Wear Behavior of NiTi Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Yan, Lina; Liu, Yong

    2016-06-01

    Owing to good biocompatibility, good fatigue resistance, and excellent superelasticity, various types of bio-medical devices based on NiTi shape memory alloy (SMA) have been developed. Due to the complexity in deformation mode in service, for example NiTi implants, accurate assessment/prediction of the surface wear process is difficult. This study aims at providing a further insight into the effect of deformation mode on the wear behavior of NiTi SMA. In the present study, two types of wear testing modes were used, namely sliding wear mode and reciprocating wear mode, to investigate the effect of deformation mode on the wear behavior of NiTi SMA in both martensitic and austenitic states. It was found that, when in martensitic state and under high applied loads, sliding wear mode resulted in more surface damage as compared to that under reciprocating wear mode. When in austenitic state, although similar trends in the coefficient of friction were observed, the coefficient of friction and surface damage in general is less under reciprocating mode than under sliding mode. These observations were further discussed in terms of different deformation mechanisms involved in the wear tests, in particular, the reversibility of martensite variant reorientation and stress-induced phase transformation, respectively.

  11. Nano-hardness, wear resistance and pseudoelasticity of hafnium implanted NiTi shape memory alloy.

    PubMed

    Zhao, Tingting; Li, Yan; Liu, Yong; Zhao, Xinqing

    2012-09-01

    NiTi shape memory alloy was modified by Hf ion implantation to improve its wear resistance and surface integrity against deformation. The Auger electron spectroscopy and x-ray photoelectron spectroscopy results indicated that the oxide thickness of NiTi alloy was increased by the formation of TiO₂/HfO₂ nanofilm on the surface. The nano-hardness measured by nano-indentation was decreased even at the depth larger than the maximum reach of the implanted Hf ion. The lower coefficient of friction with much longer fretting time indicated the remarkable improvement of wear resistance of Hf implanted NiTi, especially for the sample with a moderate incident dose. The formation of TiO₂/HfO₂ nanofilm with larger thickness and decrease of the nano-hardness played important roles in the improvement of wear resistance. Moreover, Hf implanted NiTi exhibited larger pseudoelastic recovery strain and retained better surface integrity even after being strained to 10% as demonstrated by in situ scanning electron microscope observation.

  12. Wear mechanism and tribological characteristics of porous NiTi shape memory alloy for bone scaffold.

    PubMed

    Wu, Shuilin; Liu, Xiangmei; Wu, Guosong; Yeung, Kelvin W K; Zheng, Dong; Chung, C Y; Xu, Z S; Chu, Paul K

    2013-09-01

    The abraded debris might cause osteocytic osteolysis on the interface between implants and bone tissues, thus inducing the subsequent mobilization of implants gradually and finally resulting in the failure of bone implants, which imposes restrictions on the applications of porous NiTi shape memory alloys (SMAs) scaffolds for bone tissue engineering. In this work, the effects of the annealing temperature, applied load, and porosity on the tribological behavior and wear resistance of three-dimensional porous NiTi SMA are investigated systematically. The porous structure and phase transformation during the exothermic process affect the tribological properties and wear mechanism significantly. In general, a larger porosity leads to better tribological resistance but sometimes, SMAs with small porosity possess better wear resistance than ones with higher porosity during the initial sliding stage. It can be ascribed to the better superelasticity of the former at the test temperature. The porous NiTi phase during the exothermic reaction also plays an important role in the wear resistance. Generally, porous NiTi has smaller friction coefficients under high loads due to stress-induced superelasticity. The wear mechanism is discussed based on plastic deformation and microcrack propagation.

  13. Nanoscale compositional analysis of NiTi shape memory alloy films deposited by DC magnetron sputtering

    SciTech Connect

    Sharma, S. K.; Mohan, S.; Bysakh, S.; Kumar, A.; Kamat, S. V.

    2013-11-15

    The formation of surface oxide layer as well as compositional changes along the thickness for NiTi shape memory alloy thin films deposited by direct current magnetron sputtering at substrate temperature of 300 °C in the as-deposited condition as well as in the postannealed (at 600 °C) condition have been thoroughly studied by using secondary ion mass spectroscopy, x-ray photoelectron spectroscopy, and scanning transmission electron microscopy-energy dispersive x-ray spectroscopy techniques. Formation of titanium oxide (predominantly titanium dioxide) layer was observed in both as-deposited and postannealed NiTi films, although the oxide layer was much thinner (8 nm) in as-deposited condition. The depletion of Ti and enrichment of Ni below the oxide layer in postannealed films also resulted in the formation of a graded microstructure consisting of titanium oxide, Ni{sub 3}Ti, and B2 NiTi. A uniform composition of B2 NiTi was obtained in the postannealed film only below a depth of 200–250 nm from the surface. Postannealed film also exhibited formation of a ternary silicide (Ni{sub x}Ti{sub y}Si) at the film–substrate interface, whereas no silicide was seen in the as-deposited film. The formation of silicide also caused a depletion of Ni in the film in a region ∼250–300 nm just above the film substrate interface.

  14. Static Indentation Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2012-01-01

    The nickel-rich, binary nickel-titanium alloys, such as 60NiTi (60Ni-40Ti by wt%), are emerging as viable materials for use in mechanical components like rolling element bearings and gears. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx.100 GPa). These properties result in the potential to endure extremely high indentation loads such as those encountered in bearings, gears and other mechanical components. In such applications, quantifying the load that results in permanent deformation that can affect component performance and life is important. In this paper, the static load capacity is measured by conducting indentation experiments in which 12.7 mm diameter balls made from the ceramic Si3N4 are pressed into highly polished, hardened 60NiTi flat plates. Hertz stress calculations are used to estimate contact stress. The results show that the 60NiTi surface can withstand an approximately 3400 kN load before significant denting (>0.6 microns deep) occurs. This load capacity is approximately twice that of high performance bearing steels suggesting that the potential exists to make highly resilient bearings and components from such materials.

  15. Revealing ultralarge and localized elastic lattice strains in Nb nanowires embedded in NiTi matrix

    PubMed Central

    Zang, Ketao; Mao, Shengcheng; Cai, Jixiang; Liu, Yinong; Li, Haixin; Hao, Shijie; Jiang, Daqiang; Cui, Lishan

    2015-01-01

    Freestanding nanowires have been found to exhibit ultra-large elastic strains (4 to 7%) and ultra-high strengths, but exploiting their intrinsic superior mechanical properties in bulk forms has proven to be difficult. A recent study has demonstrated that ultra-large elastic strains of ~6% can be achieved in Nb nanowires embedded in a NiTi matrix, on the principle of lattice strain matching. To verify this hypothesis, this study investigated the elastic deformation behavior of a Nb nanowire embedded in NiTi matrix by means of in situ transmission electron microscopic measurement during tensile deformation. The experimental work revealed that ultra-large local elastic lattice strains of up to 8% are induced in the Nb nanowire in regions adjacent to stress-induced martensite domains in the NiTi matrix, whilst other parts of the nanowires exhibit much reduced lattice strains when adjacent to the untransformed austenite in the NiTi matrix. These observations provide a direct evidence of the proposed mechanism of lattice strain matching, thus a novel approach to designing nanocomposites of superior mechanical properties. PMID:26625854

  16. Tungsten inert gas (TIG) welding of Ni-rich NiTi plates: functional behavior

    NASA Astrophysics Data System (ADS)

    Oliveira, J. P.; Barbosa, D.; Braz Fernandes, F. M.; Miranda, R. M.

    2016-03-01

    It is often reported that, to successfully join NiTi shape memory alloys, fusion-based processes with reduced thermal affected regions (as in laser welding) are required. This paper describes an experimental study performed on the tungsten inert gas (TIG) welding of 1.5 mm thick plates of Ni-rich NiTi. The functional behavior of the joints was assessed. The superelasticity was analyzed by cycling tests at maximum imposed strains of 4, 8 and 12% and for a total of 600 cycles, without rupture. The superelastic plateau was observed, in the stress-strain curves, 30 MPa below that of the base material. Shape-memory effect was evidenced by bending tests with full recovery of the initial shape of the welded joints. In parallel, uniaxial tensile tests of the joints showed a tensile strength of 700 MPa and an elongation to rupture of 20%. The elongation is the highest reported for fusion-welding of NiTi, including laser welding. These results can be of great interest for the wide-spread inclusion of NiTi in complex shaped components requiring welding, since TIG is not an expensive process and is simple to operate and implement in industrial environments.

  17. Microstructure and corrosion behavior of laser processed NiTi alloy.

    PubMed

    Marattukalam, Jithin J; Singh, Amit Kumar; Datta, Susmit; Das, Mitun; Balla, Vamsi Krishna; Bontha, Srikanth; Kalpathy, Sreeram K

    2015-12-01

    Laser Engineered Net Shaping (LENS™), a commercially available additive manufacturing technology, has been used to fabricate dense equiatomic NiTi alloy components. The primary aim of this work is to study the effect of laser power and scan speed on microstructure, phase constituents, hardness and corrosion behavior of laser processed NiTi alloy. The results showed retention of large amount of high-temperature austenite phase at room temperature due to high cooling rates associated with laser processing. The high amount of austenite in these samples increased the hardness. The grain size and corrosion resistance were found to increase with laser power. The surface energy of NiTi alloy, calculated using contact angles, decreased from 61 mN/m to 56 mN/m with increase in laser energy density from 20 J/mm(2) to 80 J/mm(2). The decrease in surface energy shifted the corrosion potentials to nobler direction and decreased the corrosion current. Under present experimental conditions the laser power found to have strong influence on microstructure, phase constituents and corrosion resistance of NiTi alloy.

  18. Effects of sterilization processes on NiTi alloy: surface characterization.

    PubMed

    Thierry, B; Tabrizian, M; Savadogo, O; Yahia, L

    2000-01-01

    Sterilization is required for using any device in contact with the human body. Numerous authors have studied device properties after sterilization and reported on bulk and surface modifications of many materials after processing. These surface modifications may in turn influence device biocompatibility. Still, data are missing on the effect of sterilization procedures on new biomaterials such as nickel-titanium (NiTi). Herein we report on the effect of dry heat, steam autoclaving, ethylene oxide, peracetic acid, and plasma-based sterilization techniques on the surface properties of NiTi. After processing electropolished NiTi disks with these techniques, surface analyses were performed by Auger electron spectroscopy (AES), atomic force microscopy (AFM), and contact angle measurements. AES analyses revealed a higher Ni concentration (6-7 vs. 1%) and a slightly thicker oxide layer on the surface for heat and ethylene oxide processed materials. Studies of surface topography by AFM showed up to a threefold increase of the surface roughness when disks were dry heat sterilized. An increase of the surface energy of up to 100% was calculated for plasma treated surfaces. Our results point out that some surface modifications are induced by sterilization procedures. Further work is required to assess the effect of these modifications on biocompatibility, and to determine the most appropriate methods to sterilize NiTi. PMID:10559750

  19. Capability of Sputtered Micro-patterned NiTi Thick Films

    NASA Astrophysics Data System (ADS)

    Bechtold, Christoph; Lima de Miranda, Rodrigo; Quandt, Eckhard

    2015-09-01

    Today, most NiTi devices are manufactured by a combination of conventional metal fabrication steps, e.g., melting, extrusion, cold working, etc., and are subsequently structured by high accuracy laser cutting. This combination has been proven to be very successful; however, there are several limitations to this fabrication route, e.g., in respect to the fabrication of more complex device designs, device miniaturization or the combination of different materials for the integration of further functionality. These issues have to be addressed in order to develop new devices and applications. The fabrication of micro-patterned films using magnetron sputtering, UV lithography, and wet etching has great potential to overcome limitations of conventional device manufacturing. Due to its fabrication characteristics, this method allows the production of devices with complex designs, high structural accuracy, smooth edge profile, at layer thicknesses up to 75 µm. The aim of this study is to present recent developments in the field of NiTi thin film technology, its advantages and limitations, as well as new possible applications in the medical and in non-medical fields. These developments include among others NiTi scaffold structures covered with NiTi membranes for their potential use as filters, heart valve components or aneurysm treatments, as well as micro-actuators for consumable electronics or automotive applications.

  20. Microstructure and corrosion behavior of laser processed NiTi alloy.

    PubMed

    Marattukalam, Jithin J; Singh, Amit Kumar; Datta, Susmit; Das, Mitun; Balla, Vamsi Krishna; Bontha, Srikanth; Kalpathy, Sreeram K

    2015-12-01

    Laser Engineered Net Shaping (LENS™), a commercially available additive manufacturing technology, has been used to fabricate dense equiatomic NiTi alloy components. The primary aim of this work is to study the effect of laser power and scan speed on microstructure, phase constituents, hardness and corrosion behavior of laser processed NiTi alloy. The results showed retention of large amount of high-temperature austenite phase at room temperature due to high cooling rates associated with laser processing. The high amount of austenite in these samples increased the hardness. The grain size and corrosion resistance were found to increase with laser power. The surface energy of NiTi alloy, calculated using contact angles, decreased from 61 mN/m to 56 mN/m with increase in laser energy density from 20 J/mm(2) to 80 J/mm(2). The decrease in surface energy shifted the corrosion potentials to nobler direction and decreased the corrosion current. Under present experimental conditions the laser power found to have strong influence on microstructure, phase constituents and corrosion resistance of NiTi alloy. PMID:26354269

  1. Surface modification of AISI H13 tool steel by laser cladding with NiTi powder

    NASA Astrophysics Data System (ADS)

    Norhafzan, B.; Aqida, S. N.; Chikarakara, E.; Brabazon, D.

    2016-04-01

    This paper presents laser cladding of NiTi powder on AISI H13 tool steel surface for surface properties enhancement. The cladding process was conducted using Rofin DC-015 diffusion-cooled CO2 laser system with wavelength of 10.6 µm. NiTi powder was pre-placed on H13 tool steel surface. The laser beam was focused with a spot size of 90 µm on the sample surface. Laser parameters were set to 1515 and 1138 W peak power, 18 and 24 % duty cycle and 2300-3500 Hz laser pulse repetition frequency. Hardness properties of the modified layer were characterized by Wilson Hardness tester. Metallographic study and chemical composition were conducted using field emission scanning electron microscope and energy-dispersive X-ray spectrometer (EDXS) analysis. Results showed that hardness of NiTi clad layer increased three times that of the substrate material. The EDXS analysis detected NiTi phase presence in the modified layer up to 9.8 wt%. The metallographic study shows high metallurgical bonding between substrate and modified layer. These findings are significant to both increased hardness and erosion resistance of high-wear-resistant components and elongating their lifetime.

  2. Kinetic properties and characteristics of electron-positron annihilation in NiMn and NiTi

    NASA Astrophysics Data System (ADS)

    Kal'Chikhin, V. V.; Kul'Kova, S. E.

    1992-10-01

    On the basis of the electron energy structure calculated by the self-consistent method of linear MT orbitals (the LMTO method), the kinetic properties of NiMn and NiTi are calculated from first principles. Satisfactory agreement with experimental data on the phonon electrical resistance and thermoemf is obtained for NiTi. For NiMn, the agreement of ρph(T) with experiment is only qualitative; the reasons for the quantitative discrepancy are discussed. Quasi-free position states and the contribution of various electron states in NiMn and NiTi are calculated by the LMTO method.

  3. Soil temperature and water content drive microbial carbon fixation in grassland of permafrost area on the Tibetan plateau

    NASA Astrophysics Data System (ADS)

    Kong, W.; Guo, G.; Liu, J.

    2014-12-01

    Soil microbial communities underpin terrestrial biogeochemical cycles and are greatly influenced by global warming and global-warming-induced dryness. However, the response of soil microbial community function to global change remains largely uncertain, particularly in the ecologically vulnerable Tibetan plateau permafrost area with large carbon storage. With the concept of space for time substitution, we investigated the responses of soil CO2-fixing microbial community and its enzyme activity to climate change along an elevation gradient (4400-5100 m) of alpine grassland on the central Tibetan plateau. The elevation gradient in a south-facing hill slope leads to variation in climate and soil physicochemical parameters. The autotrophic microbial communities were characterized by quantitative PCR (qPCR), terminal restriction fragment length polymorphism analysis (T-RFLP) and cloning/sequencing targeting the CO2-fixing gene (RubisCO). The results demonstrated that the autotrophic microbial community abundance, structure and its enzyme activity were mainly driven by soil temperature and water content. Soil temperature increase and water decrease dramatically reduced the abundance of the outnumbered form IC RubisCO-containing microbes, and significantly changed the structure of form IC, IAB and ID RubisCO-containing microbial community. Structural equation model revealed that the RubisCO enzyme was directly derived from RubisCO-containing microbes and its activity was significantly reduced by soil temperature increase and water content decrease. Thus our results provide a novel positive feedback loop of climate warming and warming-induced dryness by that soil microbial carbon fixing potential will reduce by 3.77%-8.86% with the soil temperature increase of 1.94oC and water content decrease of 60%-70%. This positive feedback could be capable of amplifying the climate change given the significant contribution of soil microbial CO2-fixing up to 4.9% of total soil organic

  4. Carbide Formation and Dissolution in Biomedical Co-Cr-Mo Alloys with Different Carbon Contents during Solution Treatment

    NASA Astrophysics Data System (ADS)

    Mineta, Shingo; Namba, Shigenobu; Yoneda, Takashi; Ueda, Kyosuke; Narushima, Takayuki

    2010-08-01

    The microstructures of as-cast and heat-treated biomedical Co-Cr-Mo (ASTM F75) alloys with four different carbon contents were investigated. The as-cast alloys were solution treated at 1473 to 1548 K for 0 to 43.2 ks. The precipitates in the matrix were electrolytically extracted from the as-cast and heat-treated alloys. An M23C6 type carbide and an intermetallic σ phase (Co(Cr,Mo)) were detected as precipitates in the as-cast Co-28Cr-6Mo-0.12C alloy; an M23C6 type carbide, a σ phase, an η phase (M6C-M12C type carbide), and a π phase (M2T3X type carbide with a β-manganese structure) were detected in the as-cast Co-28Cr-6Mo-0.15C alloy; and an M23C6 type carbide and an η phase were detected in the as-cast Co-28Cr-6Mo-0.25C and Co-28Cr-6Mo-0.35C alloys. After solution treatment, complete precipitate dissolution occurred in all four alloys. Under incomplete precipitate dissolution conditions, the phase and shape of precipitates depended on the heat-treatment conditions and the carbon content in the alloys. The π phase was detected in the alloys with carbon contents of 0.15, 0.25, and 0.35 mass pct after heat treatment at high temperature such as 1548 K for a short holding time of less than 1.8 ks. The presence of the π phase in the Co-Cr-Mo alloys has been revealed in this study for the first time.

  5. Compatible Models of Carbon Content of Individual Trees on a Cunninghamia lanceolata Plantation in Fujian Province, China

    PubMed Central

    Zhuo, Lin; Tao, Hong; Wei, Hong; Chengzhen, Wu

    2016-01-01

    We tried to establish compatible carbon content models of individual trees for a Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantation from Fujian province in southeast China. In general, compatibility requires that the sum of components equal the whole tree, meaning that the sum of percentages calculated from component equations should equal 100%. Thus, we used multiple approaches to simulate carbon content in boles, branches, foliage leaves, roots and the whole individual trees. The approaches included (i) single optimal fitting (SOF), (ii) nonlinear adjustment in proportion (NAP) and (iii) nonlinear seemingly unrelated regression (NSUR). These approaches were used in combination with variables relating diameter at breast height (D) and tree height (H), such as D, D2H, DH and D&H (where D&H means two separate variables in bivariate model). Power, exponential and polynomial functions were tested as well as a new general function model was proposed by this study. Weighted least squares regression models were employed to eliminate heteroscedasticity. Model performances were evaluated by using mean residuals, residual variance, mean square error and the determination coefficient. The results indicated that models with two dimensional variables (DH, D2H and D&H) were always superior to those with a single variable (D). The D&H variable combination was found to be the most useful predictor. Of all the approaches, SOF could establish a single optimal model separately, but there were deviations in estimating results due to existing incompatibilities, while NAP and NSUR could ensure predictions compatibility. Simultaneously, we found that the new general model had better accuracy than others. In conclusion, we recommend that the new general model be used to estimate carbon content for Chinese fir and considered for other vegetation types as well. PMID:26982054

  6. Compatible Models of Carbon Content of Individual Trees on a Cunninghamia lanceolata Plantation in Fujian Province, China.

    PubMed

    Zhuo, Lin; Tao, Hong; Wei, Hong; Chengzhen, Wu

    2016-01-01

    We tried to establish compatible carbon content models of individual trees for a Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantation from Fujian province in southeast China. In general, compatibility requires that the sum of components equal the whole tree, meaning that the sum of percentages calculated from component equations should equal 100%. Thus, we used multiple approaches to simulate carbon content in boles, branches, foliage leaves, roots and the whole individual trees. The approaches included (i) single optimal fitting (SOF), (ii) nonlinear adjustment in proportion (NAP) and (iii) nonlinear seemingly unrelated regression (NSUR). These approaches were used in combination with variables relating diameter at breast height (D) and tree height (H), such as D, D2H, DH and D&H (where D&H means two separate variables in bivariate model). Power, exponential and polynomial functions were tested as well as a new general function model was proposed by this study. Weighted least squares regression models were employed to eliminate heteroscedasticity. Model performances were evaluated by using mean residuals, residual variance, mean square error and the determination coefficient. The results indicated that models with two dimensional variables (DH, D2H and D&H) were always superior to those with a single variable (D). The D&H variable combination was found to be the most useful predictor. Of all the approaches, SOF could establish a single optimal model separately, but there were deviations in estimating results due to existing incompatibilities, while NAP and NSUR could ensure predictions compatibility. Simultaneously, we found that the new general model had better accuracy than others. In conclusion, we recommend that the new general model be used to estimate carbon content for Chinese fir and considered for other vegetation types as well.

  7. Effect of carbonate content on the mechanical behaviour of clay fault-gouges

    NASA Astrophysics Data System (ADS)

    Bakker, Elisenda; Niemeijer, André; Hangx, Suzanne; Spiers, Chris

    2015-04-01

    Carbon dioxide capture and storage (CCS) in depleted oil and gas reservoirs is considered to be the most promising technology to achieve large-scale reduction in anthropogenic emissions. In order to retain the stored CO2 from the atmosphere for the very long-term, i.e. on timescales of the order of 103-104 years, it is essential to maintain the integrity of the caprock, and more specifically of any faults penetrating the seal. When selecting suitable CO2-storage reservoirs, pre-exisiting faults within the caprock require close attention, as changes in the stress state resulting from CO2-injection may induce fault slip motion which might cause leakage. Little is known about the effect of fluid-rock interactions on the mineral composition, mechanical properties and the integrity and sealing capacity of the caprock. Previous studies on the effect of mineral composition on the frictional properties of fault gouges have shown that friction is controlled by the dominant phase unless there is a frictionally weak, through-going fabric. However, the effect on stability is less clear. Since long-term CO2-exposure might cause chemical reactions, potentially resulting in the dissolution or precipitation of carbonate minerals, a change in mineralogy could affect the mechanical stability of a caprock significantly. Calcite, for example, is known to be prone to micro-seismicity and shows a transition from velocity-strengthening to velocity-weakening behaviour around 100-150°C. Therefore, we investigated the effect of varying clay:carbonate ratios on fault friction behaviour, fault reactivation potential and slip stability, i.e. seismic vs. aseismic behaviour. Three types of simulated fault gouges were used: i) carbonate-free, natural clay-rich caprock samples, consisting of predominantly phyllosilicates (~80%) and quartz ~20%), ii) pure calcite, and iii) mixtures of carbonate-free clay-rich caprock and pure calcite, with predetermined clay:carbonate ratios. For the natural clay

  8. Impedimetric sensing of the ethanol and water contents in gasohol with a flow-through carbon electrode pair

    NASA Astrophysics Data System (ADS)

    Kung, Yi; Cheng, Tzong-Jih; Chen, Richie L. C.

    2013-10-01

    The ethanol in gasohol was estimated with a flow-through hydrophobic electrode pair (two identical glassy carbon electrodes, cell constant = 0.3 cm-1). Based on the impedimetric signal at 320 Hz, the important fuel quality parameter can be measured in less than 1 s with sufficient temperature tolerance (20-40 °C) and reproducibility (relative standard deviation ≤ 2% for ten tests). The water content can also be estimated by comparing the impedance data obtained with and without desiccation.

  9. A key parameter on the adsorption of diluted aniline solutions with activated carbons: The surface oxygen content.

    PubMed

    Pardo, Beatrice; Ferrer, Nabí; Sempere, Julià; Gonzalez-Olmos, Rafael

    2016-11-01

    A total of 11 different commercial activated carbons (AC) with well characterized textural properties and oxygen surface content were tested as adsorbents for the removal of aniline as a target water pollutant. The maximum adsorption capacity of aniline for the studied AC was from 138.9 to 257.9 mg g(-1) at 296.15 K and it was observed to be strongly related to the textural properties of the AC, mainly with the BET surface area and the micropore volume. It was not observed any influence of the oxygen surface content of the AC on the maximum adsorption capacity. However, it was found that at low aniline aqueous concentration, the presence of oxygen surface groups plays a dominant role during the adsorption. A high concentration of oxygen surface groups, mainly carboxylic and phenolic groups, decreases the aniline adsorption regardless of the surface area of the AC. PMID:27497348

  10. A key parameter on the adsorption of diluted aniline solutions with activated carbons: The surface oxygen content.

    PubMed

    Pardo, Beatrice; Ferrer, Nabí; Sempere, Julià; Gonzalez-Olmos, Rafael

    2016-11-01

    A total of 11 different commercial activated carbons (AC) with well characterized textural properties and oxygen surface content were tested as adsorbents for the removal of aniline as a target water pollutant. The maximum adsorption capacity of aniline for the studied AC was from 138.9 to 257.9 mg g(-1) at 296.15 K and it was observed to be strongly related to the textural properties of the AC, mainly with the BET surface area and the micropore volume. It was not observed any influence of the oxygen surface content of the AC on the maximum adsorption capacity. However, it was found that at low aniline aqueous concentration, the presence of oxygen surface groups plays a dominant role during the adsorption. A high concentration of oxygen surface groups, mainly carboxylic and phenolic groups, decreases the aniline adsorption regardless of the surface area of the AC.

  11. Reduction in the earthworm metabolomic response after phenanthrene exposure in soils with high soil organic carbon content.

    PubMed

    McKelvie, Jennifer R; Whitfield Åslund, Melissa; Celejewski, Magda A; Simpson, André J; Simpson, Myrna J

    2013-04-01

    We evaluated the correlation between soil organic carbon (OC) content and metabolic responses of Eisenia fetida earthworms after exposure to phenanthrene (58 ± 3 mg/kg) spiked into seven artificial soils with OC contents ranging from 1 to 27% OC. Principal component analysis of (1)H nuclear magnetic resonance (NMR) spectra of aqueous extracts identified statistically significant differences in the metabolic profiles of control and phenanthrene-exposed E. fetida in the 1% OC soil only. Partial least squares analysis identified a metabolic response in the four soils with OC values ≤11% which was well correlated to estimated phenanthrene porewater concentrations. The results suggest that the higher sorption capability of high OC soils decreased the bioavailability of phenanthrene and the subsequent metabolic response of E. fetida. PMID:23337355

  12. Discrepancy between Measured Serum Total Carbon Dioxide Content and Bicarbonate Concentration Calculated from Arterial Blood Gases

    PubMed Central

    Kim, Youngho; Massie, Larry; Murata, Glen H

    2015-01-01

    Large differences between the concentrations of serum total carbon dioxide (TCO2) and blood gas bicarbonate (HCO3-) were observed in two consecutive simultaneously drawn sets of samples of serum and arterial blood gases in a patient who presented with severe carbon dioxide retention and profound acidemia. These differences could not be explained by the effect of the high partial pressure of carbon dioxide on TCO2, by variations in the dissociation constant of the carbonic acid/bicarbonate system or by faults caused by the algorithms of the blood gas apparatus that calculate HCO3-. A recalculation using the Henderson-Hasselbach equation revealed arterial blood gas HCO3- values close to the corresponding serum TCO2 values and clarified the diagnosis of the acid-base disorder, which had been placed in doubt by the large differences between the reported TCO2 and HCO3- values. Human error in the calculation of HCO3- was identified as the source of these differences. Recalculation of blood gas HCO3- should be the first step in identifying the source of large differences between serum TCO2 and blood gas HCO3-. PMID:26824002

  13. Pore water chemistry in a disturbed and an undisturbed peat forests in Brunei Darussalam: Nutrient and carbon contents

    NASA Astrophysics Data System (ADS)

    Gandois, L.; Cobb, A.; Abu Salim, K.; Chieng Hei, I.; Lim Biaw Leng, L.; Corlett, R.; Harvey, C.

    2010-12-01

    Tropical peat swamp forests in their natural state are important reservoir of biodiversity, carbon and water. However, they are rapidly vanishing due to agricultural conversion (mainly to oil palms), logging, drainage and fire. Peat swamp forests constitute an important contribution to global and regional biodiversity, providing an habitat to rare and threatened species. They encompass a sequence of forest types from the perimeter to the center of mildely elevated domes, and at our site in Brunei, are host to Shorea Albida trees (Anderson, 1983). They constitute a large terrestrial carbon reservoir (tropical peat soils contain up to 70 Pg C, which accounts for 20% of global peat soil carbon and 2% of the global soil carbon (Hirano et al., 2007)). In tropical peat swamp forests, the most important factors controling organic matter accumulation, as well as the biodiversity and structure of the forest, are hydrology and nutrients availability (Page et al., 1999). Study of pore water in peat swamp forest can provide key information on carbon cycle, including biomass production, organic matter decomposition and leaching of carbon in draining water. However, data on pore water chemistry and nutrient concentrations in pristine tropical peatlands, as well as the effect of forest exploitation are scarce. The study area is located in the Belait district in Brunei Darussalam in Borneo Island. Brunei is perhaps the best of the regional guardians of peat forest systems; potentially irreversible damage to peat forest ecosystems has been widespread elsewhere. Two sites, one pristine dome and a logging concession, are being investigated. In order to assess the chemical status of the peat soil, pore water is sampled at different depth along the dome radius. The chemistry of pore water, including pH, conductivity, dissolved oxygen, concentration of major elements, as well as organic carbon content and properties are analyzed. References: Anderson, 1983. The tropical peat swamp of

  14. Surface Modification of NiTi Alloy via Cathodic Plasma Electrolytic Deposition and its Effect on Ni Ion Release and Osteoblast Behaviors

    NASA Astrophysics Data System (ADS)

    Yan, Ying; Cai, Kaiyong; Yang, Weihu; Liu, Peng

    2013-07-01

    To reduce Ni ion release and improve biocompatibility of NiTi alloy, the cathodic plasma electrolytic deposition (CPED) technique was used to fabricate ceramic coating onto a NiTi alloy surface. The formation of a coating with a rough and micro-textured surface was confirmed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, respectively. An inductively coupled plasma mass spectrometry test showed that the formed coating significantly reduced the release of Ni ions from the NiTi alloy in simulated body fluid. The influence of CPED treated NiTi substrates on the biological behaviors of osteoblasts, including cell adhesion, cell viability, and osteogenic differentiation function (alkaline phosphatase), was investigated in vitro. Immunofluorescence staining of nuclei revealed that the CPED treated NiTi alloy was favorable for cell growth. Osteoblasts on CPED modified NiTi alloy showed greater cell viability than those for the native NiTi substrate after 4 and 7 days cultures. More importantly, osteoblasts cultured onto a modified NiTi sample displayed significantly higher differentiation levels of alkaline phosphatase. The results suggested that surface functionalization of NiTi alloy with ceramic coating via the CPED technique was beneficial for cell proliferation and differentiation. The approach presented here is useful for NiTi implants to enhance bone osseointegration and reduce Ni ion release in vitro.

  15. Influence of Hydrogen Content on Optical and Mechanical Performances of Diamond-Like Carbon Films on Glass Substrate

    NASA Astrophysics Data System (ADS)

    Sun, Yao; Huang, Xing-Ye; Wang, Hong

    2016-04-01

    The protective layer for cover glass of touch panel screen for electronic mobile devices is required to have good mechanical properties and decent optical transparency simultaneously. The hydrogenated diamond-like carbon (a-C:H) films were deposited on glass substrate by RF-PECVD in the negative stage potential mode (NP mode), as well as the ground stage potential mode (GP mode). The impact of hydrogen content, affected by stage potential and RF power, on optical and mechanical properties was investigated. The results show that hydrogen content decreases with increasing RF power, due to the dehydrogenation effect. Higher hydrogen content in films results in lower refractive index, lower extinction coefficient, lower optical absorptions, larger optical band gap and higher transmittance, but lower hardness and wearing resistance. Therefore, although the GP mode DLC is optically favorable because of higher hydrogen content, the NP mode one is far more superior from mechanical standpoint. A compromise can be reached to deposit an ultrathin layer of DLC in NP mode, which offers a good combination of properties to meet the requirement for the protective layer of cover glass.

  16. Adsorption of lead on multi-walled carbon nanotubes with different outer diameters and oxygen contents: kinetics, isotherms and thermodynamics.

    PubMed

    Yu, Fei; Wu, Yanqing; Ma, Jie; Zhang, Chi

    2013-01-01

    The effects of different outer diameters and surface oxygen contents on the adsorption of heavy metals onto six types of multi-walled carbon nanotubes (MWCNTs) were investigated in an aqueous solution and lead was chosen as a model metal ion. The results indicated that the percentage removal and adsorption capacity of lead remarkably increased with decreasing outer diameter due to larger specific surface area (SSA). The SSA-normalized maximum adsorption capacity (qmSSA) and SSA-normalized adsorption coefficient (Kd/SSA) were strongly positively correlated with surface oxygen content, implying that lead adsorption onto MWCNTs significantly increases with the rise of oxygen content and decreases with decreasing SSA. The calculated thermodynamic parameters indicated that adsorption of lead on MWCNTs was endothermic and spontaneous. When the oxygen content of MWCNTs increased from 2.0% to 5.9%, the standard free energy (deltaG0) became more negative, which implied that the oxygenated functional groups increased the adsorption affinity of MWCNTs for lead. Through calculation of enthalpy (deltaH0), deltaG0 and free energy of adsorption (Ea), lead adsorption onto MWCNTs was recognized as a chemisorption process. The chemical interaction between lead and the phenolic groups of MWCNTs could be one of the main adsorption mechanisms due to highly positive correlations between the phenolic groups and Kd/SSA or qm/SSA.

  17. Cleaning Effectiveness of Three NiTi Rotary Instruments: A Focus on Biomaterial Properties

    PubMed Central

    Poggio, Claudio; Dagna, Alberto; Chiesa, Marco; Beltrami, Riccardo; Bianchi, Stefano

    2015-01-01

    Nickel-titanium (NiTi) instruments are commonly used for shaping the root canal system in endodontic practice. They are more flexible and have better cutting efficiency than conventional stainless steel files. The superelasticity of NiTi rotary files allows the clinicians to produce the desirable tapered root canal form with a reduced tendency to canal transportation and instrument fracture. HyFlex CM instruments are new NiTi rotary instruments with shape memory produced by an innovative methodology (patent pending) that uses a complex heating and cooling treatment that controls the material’s memory. The aim of the present study was to compare the cleaning efficacy of two conventional (Mtwo, Revo-S) Ni-Ti rotary instruments with HyFlex CM. 30 single-rooted freshly extracted teeth were divided into three groups. Root canals were shaped with three NiTi instruments (Mtwo, Revo-S and HyFlex CM) using 5.25% NaOCl and 17% EDTA solutions. Specimens were fractured longitudinally and prepared for SEM analysis at standard magnification of 1000×. The presence/absence of debris smear layer and the presence/absence of smear layer at coronal, middle, and apical third of each canal were evaluated using a 5-step scale for scores. Numeric data were analyzed using Kruskall-Wallis and Mann-Whitney U statistical tests and significance was predetermined at P < 0.05. This study revealed significant differences among the various groups. Despite some minor differences, all instruments removed smear layer and debris produced during instrumentation. HyFlex CM seem to be not so effective in promoting cleanliness of root canal walls and in removing smear layer from dentine if compared to Mtwo and Revo-S. PMID:25692796

  18. Microwave absorbing properties of polyaniline/multi-walled carbon nanotube composites with various polyaniline contents

    NASA Astrophysics Data System (ADS)

    Ting, T. H.; Jau, Y. N.; Yu, R. P.

    2012-01-01

    Polyaniline/multi-walled carbon nanotube (PANI/MWNT) composites were synthesized using in situ polymerization at different aniline/multi-walled carbon nanotube weight ratios (Ani/MWNT = 1/2, 1/1, 2/1 and 3/1) and introduced into an epoxy resin to act as a microwave absorber. The spectroscopic characterization of the process of formation of PANI/MWNT composites were studied using Fourier transform infrared spectroscopy, an ultraviolet-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron spin resonance. The microwave absorbing properties were investigated by measuring complex permittivity, complex permeability and reflection loss in the 2-18 and 18-40 GHz microwave frequency range, using the free space method. The results showed that the addition of PANI was useful for achieving a large absorption over a wide frequency range, especially for higher frequency values.

  19. Spectroscopic characteristics and organic carbon contents in the aerosols collected in Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Potter, H. J.; Kasaba, T.

    2015-12-01

    Organics in the atmospheric aerosols occupy 20 to 70% of the total mass. Since the proportion of organics is so large that it's important to understand their detailed characteristics. Polymeric compounds called HUmic-Like Substance (HULIS) are known to be present in the atmospheric aerosols. Biomass burning can be a source of HULIS. In this study, atmospheric aerosols were collected at Cape Hedo, a northern tip of Okinawa Island, and we characterized overall features of the organics collected in different seasons. In Okinawa, continental air mass prevails in spring, fall and winter, while maritime air mass from Pacific Ocean prevails in summer. Thus, it is relatively straightforward to identify sources of organics in different seasons. We measured total organic carbon (TOC) and water soluble organic carbon (WSOC) concentrations, and absorbance and fluorescence intensity for the aerosol samples collected during Nov 2012 and July 2014 (n=90). As a result, TOC and WSOC showed almost the same trend, higher concentrations when continental air mass prevailed in fall and winter, while lower concentrations in summer. Percentages of WSOC in TOC accounted for 33-44%. Absorption efficiency, absorbance per 1 ppm organic carbon concentration, of the samples showed higher values in winter and fall, and lower values in summer. Fluorescence efficiency, normalized fluorescence with quinine sulfate per 1 ppm organic carbon concentration, were also different, it is likely that different types of organics were present in the aerosols from different seasons. We are also planning to measure HULIS in the aerosols and will be discussed a link between their contribution and trans-boundary air pollution in Asia.

  20. Temporal trends in organic carbon content in the main Swiss rivers, 1974-2010.

    PubMed

    Rodríguez-Murillo, J C; Zobrist, J; Filella, M

    2015-01-01

    Increases in dissolved organic carbon (DOC) concentrations have often been reported in rivers and lakes of the Northern Hemisphere over the last few decades. High-quality organic carbon (OC) concentration data have been used to study the change in DOC and total (TOC) organic carbon concentrations in the main rivers of Switzerland (Rhône, Rhine, Thur and Aar) between 1974 and 2010. These rivers are characterized by high discharge regimes (due to their Alpine origin) and by running in populated areas. Small long term trends (a general statistically significant decrease in TOC and a less clear increase in DOC concentrations), on the order of 1% of mean OC concentration per year, have been observed. An upward trend before 1999 reversed direction to a more marked downward trend from 1999 to 2010. Of the potential causes of OC temporal variation analysed (water temperature, dissolved reactive phosphorus and river discharge), only discharge explains a significant, albeit still small, part of TOC variability (8-31%), while accounting for barely 2.5% of DOC variability. Estimated anthropogenic TOC and DOC loads (treated sewage) to the rivers could account for a maximum of 4-20% of the temporal trends. Such low predictability is a good example of the limitations faced when studying causality and drivers behind small variations in complex systems. River export of OC from Switzerland has decreased significantly over the period. Since about 5.5% of estimated NEP of Switzerland is exported by the rivers, riverine OC fluxes should be taken into account in a detailed carbon budget of the country.

  1. Voltammetric determination of polyphenolic content in pomegranate juice using a poly(gallic acid)/multiwalled carbon nanotube modified electrode

    PubMed Central

    Newair, Emad F

    2016-01-01

    Summary A simple and sensitive poly(gallic acid)/multiwalled carbon nanotube modified glassy carbon electrode (PGA/MWCNT/GCE) electrochemical sensor was prepared for direct determination of the total phenolic content (TPC) as gallic acid equivalent. The GCE working electrode was electrochemically modified and characterized using scanning electron microscope (SEM), cyclic voltammetry (CV), chronoamperometry and chronocoulometry. It was found that gallic acid (GA) exhibits a superior electrochemical response on the PGA/MWCNT/GCE sensor in comparison with bare GCE. The results reveal that a PGA/MWCNT/GCE sensor can remarkably enhance the electro-oxidation signal of GA as well as shift the peak potentials towards less positive potential values. The dependence of peak current on accumulation potential, accumulation time and pH were investigated by square-wave voltammetry (SWV) to optimize the experimental conditions for the determination of GA. Using the optimized conditions, the sensor responded linearly to a GA concentration throughout the range of 4.97 × 10−6 to 3.38 × 10−5 M with a detection limit of 3.22 × 10−6 M (S/N = 3). The fabricated sensor shows good selectivity, stability, repeatability and (101%) recovery. The sensor was successfully utilized for the determination of total phenolic content in fresh pomegranate juice without interference of ascorbic acid, fructose, potassium nitrate and barbituric acid. The obtained data were compared with the standard Folin–Ciocalteu spectrophotometric results. PMID:27547628

  2. Voltammetric determination of polyphenolic content in pomegranate juice using a poly(gallic acid)/multiwalled carbon nanotube modified electrode.

    PubMed

    Abdel-Hamid, Refat; Newair, Emad F

    2016-01-01

    A simple and sensitive poly(gallic acid)/multiwalled carbon nanotube modified glassy carbon electrode (PGA/MWCNT/GCE) electrochemical sensor was prepared for direct determination of the total phenolic content (TPC) as gallic acid equivalent. The GCE working electrode was electrochemically modified and characterized using scanning electron microscope (SEM), cyclic voltammetry (CV), chronoamperometry and chronocoulometry. It was found that gallic acid (GA) exhibits a superior electrochemical response on the PGA/MWCNT/GCE sensor in comparison with bare GCE. The results reveal that a PGA/MWCNT/GCE sensor can remarkably enhance the electro-oxidation signal of GA as well as shift the peak potentials towards less positive potential values. The dependence of peak current on accumulation potential, accumulation time and pH were investigated by square-wave voltammetry (SWV) to optimize the experimental conditions for the determination of GA. Using the optimized conditions, the sensor responded linearly to a GA concentration throughout the range of 4.97 × 10(-6) to 3.38 × 10(-5) M with a detection limit of 3.22 × 10(-6) M (S/N = 3). The fabricated sensor shows good selectivity, stability, repeatability and (101%) recovery. The sensor was successfully utilized for the determination of total phenolic content in fresh pomegranate juice without interference of ascorbic acid, fructose, potassium nitrate and barbituric acid. The obtained data were compared with the standard Folin-Ciocalteu spectrophotometric results.

  3. X-ray fluorescence as a method of monitoring metal catalyst content during the purification of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cavness, Brandon; Heimbecker, Joshua; Velasquez, Joe; Williams, S.

    2012-02-01

    There have been several studies that suggest that catalyst metals in carbon nanotubes (CNTs) may pose a health threat. As there are many potential applications of CNTs in medicine, it is important to be able to quantitatively determine the amount of metal catalyst contained in a CNT sample. The relative catalyst content of carbon nanotube samples synthesized via arc-discharge has been determined at various stages of the purification process using X-ray fluorescence (XRF) analysis. Purification was achieved by immersing samples in heated nitric acid. The intensities of the nickel K α X-rays were studied to determine the relative catalyst content in the samples. Scanning electron microscopy (SEM) images of purified nanotubes have been compared to the images of a sample that has been irradiated by 0-15 keV bremsstrahlung in order to determine if the XRF analysis of the nanotubes is in any way destructive. No obvious structural defects were observed as the result of irradiation.

  4. Voltammetric determination of polyphenolic content in pomegranate juice using a poly(gallic acid)/multiwalled carbon nanotube modified electrode.

    PubMed

    Abdel-Hamid, Refat; Newair, Emad F

    2016-01-01

    A simple and sensitive poly(gallic acid)/multiwalled carbon nanotube modified glassy carbon electrode (PGA/MWCNT/GCE) electrochemical sensor was prepared for direct determination of the total phenolic content (TPC) as gallic acid equivalent. The GCE working electrode was electrochemically modified and characterized using scanning electron microscope (SEM), cyclic voltammetry (CV), chronoamperometry and chronocoulometry. It was found that gallic acid (GA) exhibits a superior electrochemical response on the PGA/MWCNT/GCE sensor in comparison with bare GCE. The results reveal that a PGA/MWCNT/GCE sensor can remarkably enhance the electro-oxidation signal of GA as well as shift the peak potentials towards less positive potential values. The dependence of peak current on accumulation potential, accumulation time and pH were investigated by square-wave voltammetry (SWV) to optimize the experimental conditions for the determination of GA. Using the optimized conditions, the sensor responded linearly to a GA concentration throughout the range of 4.97 × 10(-6) to 3.38 × 10(-5) M with a detection limit of 3.22 × 10(-6) M (S/N = 3). The fabricated sensor shows good selectivity, stability, repeatability and (101%) recovery. The sensor was successfully utilized for the determination of total phenolic content in fresh pomegranate juice without interference of ascorbic acid, fructose, potassium nitrate and barbituric acid. The obtained data were compared with the standard Folin-Ciocalteu spectrophotometric results. PMID:27547628

  5. The Effect of Active Phase of the Work Material on Machining Performance of a NiTi Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Kaynak, Yusuf; Karaca, Haluk E.; Noebe, Ronald D.; Jawahir, I. S.

    2015-06-01

    Poor machinability with conventional machining processes is a major shortcoming that limits the manufacture of NiTi components. To better understand the effects of phase state on the machining performance of NiTi alloys, cutting temperature, tool-wear behavior, cutting force components, tool-chip contact length, chip thickness, and machined surface quality data were generated from a NiTi alloy using precooled cryogenic, dry, minimum quantity lubrication (MQL), and preheated machining conditions. Findings reveal that machining NiTi in the martensite phase, which was achieved through precooled cryogenic machining, profoundly improved the machining performance by reducing cutting force components, notch wear, and surface roughness. Machining in the austenite state, achieved through preheating, did not provide any benefit over dry and MQL machining, and these processes were, in general, inferior to cryogenic machining in terms of machining performance, particularly at higher cutting speeds.

  6. Pickling of laser-cut NiTi slotted tube stents: Effect on surface morphology, dimension changes and mechanical behaviour

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Stalmans, R.; van Humbeeck, J.; de Scheerder, I.

    2003-10-01

    Production of the NiTi slotted tube stents by laser cutting leads to strong burr formation and depositions on the material surface. Acid pickling is one of the major methods to remove the burr and the depositions. In this study, as a pre-treatment of polishing the NiTi stents, pickling was tested for various times in an acid solution at room temperature. Its effect on the surface morphology, dimension changes, and mechanical behaviour of the NiTi stents was evaluated. The burr and depositions could be removed practically. The removal (weight loss) of the material increases linearly with the pickling time. The burr and depositions were removed totally from the cutting zone when pickling time reached a specific value. Experimental relations among weight loss, dimensions, mechanical properties and pickling time of the NiTi stents were established.

  7. Distributions of Manganese, Iron, and Manganese-Oxidizing Bacteria In Lake Superior Sediments of Different Organic Carbon Content

    NASA Technical Reports Server (NTRS)

    Richardson, Laurie L.; Nealson, Kenneth H.

    1989-01-01

    Profiles of oxygen, soluble and particulate manganese and iron, organic carbon and nitrogen were examined in Lake Superior sediment cores, along with the distribution and abundance of heterotrophic and manganese oxidizing bacteria. Analyses were performed using cores collected with the submersible Johnson Sea Link II. Three cores, exhibiting a range of organic carbon content, were collected from the deepest basin in Lake Superior and the north and south ends of the Caribou trough, and brought to the surface for immediate analysis. Minielectrode profiles of oxygen concentration of the three cores were carried out using a commercially available minielectrode apparatus. Oxygen depletion to less than 1% occurred within 4 cm of the surface for two of the cores, but not until approximately 15 cm for the core from the south basin of the Caribou trough. The three cores exhibited very different profiles of soluble, as well as leachable, manganese and iron, suggesting different degrees of remobilization of these metals in the sediments. Vertical profiles of viable bacteria and Mn oxidizing bacteria, determined by plating and counting, showed that aerobic (and facultatively aerobic) heterotrophic bacteria were present at the highest concentrations near the surface and decreased steadily with depth, while Mn oxidizing bacteria were concentrations primarily at and above the oxic/anoxic interface. Soluble manganese in the pore waters, along with abundant organic carbon, appeared to enhance the presence of manganese oxidizing bacteria, even below the oxic/anoxic interface. Profiles of solid-phase leachable manganese suggested a microbial role in manganese reprecipitation in these sediments.

  8. Measurement of contemporary and fossil carbon contents of PM 2.5 aerosols: results from Turtleback Dome, Yosemite National Park

    SciTech Connect

    Bench, G

    2003-10-17

    The impact of aerosol particulate matter of mean mass aerodynamic diameter {le} 2.5 {proportional_to}m (PM 2.5 aerosols), on health, visibility, and compliance with EPA's regional haze regulations is a growing concern. Techniques that can help better characterize particulate matter are required to better understand the constituents, causes and sources of PM 2.5 aerosols. Measurement of the {sup 14}C/C ratio of the PM 2.5 aerosols, the absence of {sup 14}C in fossil carbon materials and the known {sup 14}C/C levels in contemporary carbon materials allows use of a two-component model to derive contemporary and fossil carbon contents of the particulate matter. Such data can be used to estimate the relative contributions of fossil fuels and biogenic aerosols to the total aerosol loading. Here, the methodology for performing such an assessment using total suspended particulate Hi-vol aerosol samplers to collect PM 2.5 aerosols on quartz fiber filters and the technique of accelerator mass spectrometry to measure {sup 14}C/C ratios is presented and illustrated using PM 2.5 aerosols collected at Yosemite National Park.

  9. Distributions of manganese, iron, and manganese-oxidizing bacteria in Lake Superior sediments of different organic carbon content

    SciTech Connect

    Richardson, L.L.; Nealson, K.H.

    1989-01-01

    Profiles of oxygen, soluble and particulate manganese and iron, organic carbon and nitrogen were examined in Lake Superior sediment cores, along with the distribution and abundance of heterotrophic and manganese oxidizing bacteria. Analyses were performed using cores collected with the submersible Johnson Sea Link II. Three cores, exhibiting a range of organic carbon content, were collected from the deepest basin in Lake Superior and the north and south ends of the Caribou trough, and brought to the surface for immediate analysis. Minielectrode profiles of oxygen concentration of the three cores were carried out using a commercially available minielectrode apparatus. Oxygen depletion to less than 1% occurred within 4 cm of the surface for two of the cores, but not until approximately 15 cm for the core from the south basin of the Caribou trough. The three cores exhibited very different profiles of soluble, as well as leachable, manganese and iron, suggesting different degrees of remobilization of these metals in the sediments. Vertical profiles of viable bacterial and Mn oxidizing bacteria, determined by plating and counting, showed that aerobic heterotrophic bacteria were present at the highest concentrations near the surface and decreased steadily with depth, while Mn oxidizing bacteria were concentrated primarily at and above the oxic/anoxic interface. Soluble manganese in the pore waters, along with abundant organic carbon, appeared to enhance the presence of manganese oxidizing bacteria, even below the oxic/anoxic interface. Profiles of solid-phase leachable manganese suggested a microbial role in manganese reprecipitation in these sediments.

  10. Frozen Quaternary Deposits of the Laptev Sea Region as a Reservoir of Organic Carbon: Total Content and Composition.

    NASA Astrophysics Data System (ADS)

    Kholodov, A.; Schirrmeister, L.; Shirshova, L.; Zolotareva, B.; Meyer, H.; Knoblauch, C.; Fahl, K.

    2007-12-01

    Permafrost is a significant reservoir and potential source of ancient organic matter (OM) such as plant remains, humified organics, etc. and greenhouse gases. In according with different estimations 1 cubic meter of frozen deposits in this region consists up to 10 kg of Corg. Due to the degradation of permafrost under the both modern geological processes and global warming, this organic carbon is easily released into the present biogeochemical cycle Humus parameters, elementary and isotopic composition of OM, dissolved organic carbon content and some biomarkers in the following types of quaternary deposits were determined: Middle Pleistocene deposits contain 1-2% of TOC and characterised by the ratios of C/N 5-7,5 (syncryogenic) and 10-12 (epycryogenic). Late Pleistocene syncryogenic deposits composed by true syncryogenic deposits and buried soils. The former characterized by the 1-2% of TOC and C/N ratio 9-11 the later 4-16% of TOC and 12-16 C/N ratio. Late Pleistocene-Holocene taberal deposits. TOC - 1%, C/N - 10-12 Holocene alas deposits. TOC 4-6%, C/N - 10-12. Main part of total carbon is organic origin. Carbonates consist only 31 - 20 %. The following conclusions can be done: More transformed OM is in the buried soils and alas deposits. OM of syncryogenic deposits is a most labile. TOC and stage of organic matter transformation in the syncryogenic deposits depends on ratio of sedimentation and freezing rate. Decreasing of freezing rate leads to the more deposition and to deeper transformation of OM. Most transformed OM is in alas deposits and buried soils. About 20% of TOC presented by humus. Syncryogenic and taberal deposits are not so matured (humus content 15%). Content of organic matter potentially available to be dissolved in the water is low in the all investigated deposits. It consists approximately the 1-1,5% of TOC in Ice Complex deposits and 2-3% in alas and taberal deposits. Determination of biomarkers composition (n-alkanes, fatty acids and sterols

  11. Epidermal carbonic anhydrase activity and exoskeletal metal content during the molting cycle of the blue crab, Callinectes sapidus.

    PubMed

    Calhoun, Stacy; Zou, Enmin

    2016-03-01

    During the crustacean molting cycle, the exoskeleton is first mineralized in postmolt and intermolt and then presumably demineralized in premolt in order for epidermal retraction to occur. The mineralization process calls for divalent metal ions, such as Ca(2+) and Mg(2+) , and bicarbonate ions whereas protons are necessary for dissolution of carbonate salts. Carbonic anhydrase (CA) has been suggested to be involved in exoskeletal mineralization by providing bicarbonate ions through catalyzing the reaction of carbon dioxide hydration. However, results of earlier studies on the role of epidermal CA in metal incorporation in crustacean exoskeleton are not consistent. This study was aimed to provide further evidence to support the notion that epidermal CA is involved in exoskeletal mineralization using the blue crab, Callinectes sapidus (Rathbun 1896), as the model crustacean. Significant increases first in calcium and magnesium then in manganese post-ecdysis indicate significant metal deposition during postmolt and intermolt. Significant positive correlation between calcium or magnesium content and epidermal CA activity in postmolt and intermolt constitutes evidence that CA is involved in the mineralization of the crustacean exoskeleton. Additionally, we proposed a hypothetical model to describe the role of epidermal CA in both mineralization and demineralization of the exoskeleton based on the results of epidermal CA activity and exoskeletal metal content during the molting cycle. Furthermore, we found that the pattern of epidermal CA activity during the molting cycle of C. sapidus is similar to that of ecdysteroids reported for the same species, suggesting that epidermal CA activity may be under control of the molting hormones. PMID:26935248

  12. Epidermal carbonic anhydrase activity and exoskeletal metal content during the molting cycle of the blue crab, Callinectes sapidus.

    PubMed

    Calhoun, Stacy; Zou, Enmin

    2016-03-01

    During the crustacean molting cycle, the exoskeleton is first mineralized in postmolt and intermolt and then presumably demineralized in premolt in order for epidermal retraction to occur. The mineralization process calls for divalent metal ions, such as Ca(2+) and Mg(2+) , and bicarbonate ions whereas protons are necessary for dissolution of carbonate salts. Carbonic anhydrase (CA) has been suggested to be involved in exoskeletal mineralization by providing bicarbonate ions through catalyzing the reaction of carbon dioxide hydration. However, results of earlier studies on the role of epidermal CA in metal incorporation in crustacean exoskeleton are not consistent. This study was aimed to provide further evidence to support the notion that epidermal CA is involved in exoskeletal mineralization using the blue crab, Callinectes sapidus (Rathbun 1896), as the model crustacean. Significant increases first in calcium and magnesium then in manganese post-ecdysis indicate significant metal deposition during postmolt and intermolt. Significant positive correlation between calcium or magnesium content and epidermal CA activity in postmolt and intermolt constitutes evidence that CA is involved in the mineralization of the crustacean exoskeleton. Additionally, we proposed a hypothetical model to describe the role of epidermal CA in both mineralization and demineralization of the exoskeleton based on the results of epidermal CA activity and exoskeletal metal content during the molting cycle. Furthermore, we found that the pattern of epidermal CA activity during the molting cycle of C. sapidus is similar to that of ecdysteroids reported for the same species, suggesting that epidermal CA activity may be under control of the molting hormones.

  13. Effect of sulfur content in a sulfur-activated carbon composite on the electrochemical properties of a lithium/sulfur battery

    SciTech Connect

    Park, Jin-Woo; Kim, Changhyeon; Ryu, Ho-Suk; Cho, Gyu-Bong; Cho, Kwon-Koo; Kim, Ki-Won; Ahn, Jou-Hyeon; Wang, Guoxiu; Ahn, Jae-Pyeung; Ahn, Hyo-Jun

    2015-09-15

    Highlights: • The content of sulfur in activated carbon was controlled by solution process. • The sulfur electrode with low sulfur content shows the best performance. • The Li/S battery has capacity of 1360 mAh/g at 1 C and 702 mAh/g at 10 C. - Abstract: The content of sulfur in sulfur/activated carbon composite is controlled from 32.37 wt.% to 55.33 wt.% by a one-step solution-based process. When the sulfur content is limited to 41.21 wt.%, it can be loaded into the pores of an activated carbon matrix in a highly dispersed state. On the contrary, when the sulfur content is 55.33 wt.%, crystalline sulfur can be detected on the surface of the activated carbon matrix. The best electrochemical performance can be obtained for a sulfur electrode with the lowest sulfur content. The sulfur/activated carbon composite with 32.37 wt.% sulfur afforded the highest first discharge capacity of 1360 mAh g{sup −1} at 1 C rate and a large reversible capacity of 702 mAh g{sup −1} at 10 C (16.75 A/g)

  14. Carbon and other light element contents in the Earth’s core based on first-principles molecular dynamics

    PubMed Central

    Zhang, Yigang; Yin, Qing-Zhu

    2012-01-01

    Carbon (C) is one of the candidate light elements proposed to account for the density deficit of the Earth’s core. In addition, C significantly affects siderophile and chalcophile element partitioning between metal and silicate and thus the distribution of these elements in the Earth’s core and mantle. Derivation of the accretion and core–mantle segregation history of the Earth requires, therefore, an accurate knowledge of the C abundance in the Earth’s core. Previous estimates of the C content of the core differ by a factor of ∼20 due to differences in assumptions and methods, and because the metal–silicate partition coefficient of C was previously unknown. Here we use two-phase first-principles molecular dynamics to derive this partition coefficient of C between liquid iron and silicate melt. We calculate a value of 9 ± 3 at 3,200 K and 40 GPa. Using this partition coefficient and the most recent estimates of bulk Earth or mantle C contents, we infer that the Earth’s core contains 0.1–0.7 wt% of C. Carbon thus plays a moderate role in the density deficit of the core and in the distribution of siderophile and chalcophile elements during core–mantle segregation processes. The partition coefficients of nitrogen (N), hydrogen, helium, phosphorus, magnesium, oxygen, and silicon are also inferred and found to be in close agreement with experiments and other geochemical constraints. Contents of these elements in the core derived from applying these partition coefficients match those derived by using the cosmochemical volatility curve and geochemical mass balance arguments. N is an exception, indicating its retention in a mantle phase instead of in the core. PMID:23150591

  15. Nitrogen-doped carbon and high-content alumina containing bi-active cobalt oxides for efficient storage of lithium.

    PubMed

    Wu, Bibo; Zhang, Shilin; Yao, Feng; Huo, Ruijie; Zhang, Fazhi; Xu, Sailong

    2016-01-15

    Low-content ultrathin coating of non-active alumina (Al2O3) has been extensively utilized as one of the most effective strategies to improve electrochemical performances of electrodes for lithium-ion batteries (LIBs), however, typically by employing expensive atomic layer deposition equipment. We herein demonstrate a simple preparation of high-content and well-dispersed Al2O3 (24.33wt.%)-containing multi-component composite (CoO/Co3O4/N-C/Al2O3) by calcination of melamine/CoAl-layered double hydroxide (CoAl-LDH) mixture. The resulting composite bundles the advantages expected to improve electrochemical performances: (i) bi-active CoO/Co3O4, (ii) highly conductive N-doped carbon, and (iii) N-doped carbon and high-content non-active Al2O3 as buffering reagents, as well as (iv) good distribution of bi- and non-active components resulted from the lattice orientation and confinement effect of the LDH layers. Electrochemical evaluation shows that the composite electrode delivers a highly enhanced reversible capacity of 1078mAhg(-1) after 50cycles at 100mAg(-1), compared with the bi-active CoO/Co3O4 mixtures with and without non-active Al2O3. Transmission electron microscopy/scanning electron microscopy observations and electrochemical impedance spectra experimentally provide the information on the good distributions of multiple components and the improved conductivity underlying the enhancements, respectively. Our LDH precursor-based preparation route may be extended to design and prepare various multi-component transition metal oxides for efficient lithium storage.

  16. Determining the modern carbon content of biobased products using radiocarbon analysis.

    PubMed

    Norton, Glenn A; Devlin, Steven L

    2006-11-01

    In support of the USDA Federal Biobased Products Preferred Procurement Program (FB4P), Iowa State University is coordinating testing to determine the "biobased content" of manufactured products. These tests are part of a process to "designate" items that qualify for preferential procurement status with federal agencies. Biobased content determinations are being performed using three radiocarbon dating procedures specified in ASTM D 6866-05. Test results obtained thus far indicate that the AMS and benzene synthesis methods provide comparable results. Data from the CO(2) cocktail method did not agree as well with the data from the other two methods, but were still in reasonably good agreement with those data. Radiocarbon analysis is shown to be a reliable and valuable tool for verifying the biobased content of a wide variety of biobased products. Based on inter- and intra-laboratory comparisons, a reasonable uncertainty to associate with the analyses would be +/-3% (absolute) for the AMS and benzene synthesis methods. Because of limited data availability, additional work is needed to establish the uncertainty of the CO(2) cocktail method for analyzing biobased products.

  17. Ni ion release, osteoblast-material interactions, and hemocompatibility of hafnium-implanted NiTi alloy.

    PubMed

    Zhao, Tingting; Li, Yan; Zhao, Xinqing; Chen, Hong; Zhang, Tao

    2012-04-01

    Hafnium ion implantation was applied to NiTi alloy to suppress Ni ion release and enhance osteoblast-material interactions and hemocompatibility. The auger electron spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscope results showed that a composite TiO(2)/HfO(2) nanofilm with increased surface roughness was formed on the surface of NiTi, and Ni concentration was reduced in the superficial surface layer. Potentiodynamic polarization tests displayed that 4 mA NiTi sample possessed the highest E(br) - E(corr), 470 mV higher than that of untreated NiTi, suggesting a significant improvement on pitting corrosion resistance. Inductively coupled plasma mass spectrometry tests during 60 days immersion demonstrated that Ni ion release rate was remarkably decreased, for example, a reduction of 67% in the first day. The water contact angle increased and surface energy decreased after Hf implantation. Cell culture and methyl-thiazol-tetrazolium indicated that Hf-implanted NiTi expressed enhanced osteoblasts adhesion and proliferation, especially after 7 days culture. Hf implantation decreased fibrinogen adsorption, but had almost no effect on albumin adsorption. Platelets adhesion and activation were suppressed significantly (97% for 4 mA NiTi) and hemolysis rate was decreased by at least 57% after Hf implantation. Modified surface composition and morphology and decreased surface energy should be responsible for the improvement of cytocompatibility and hemocompatibility.

  18. A bridge column with superelastic NiTi SMA and replaceable rubber hinge for earthquake damage mitigation

    NASA Astrophysics Data System (ADS)

    Varela, Sebastian; ‘Saiid’ Saiidi, M.

    2016-07-01

    This paper reports a unique concept for resilient bridge columns that can undergo intense earthquake loading and remain functional with minimal damage and residual drift. In this concept, the column is designed so that its components can be easily disassembled and reassembled to facilitate material recycling and component reuse. This is meant to foster sustainability of bridge systems while minimizing monetary losses from earthquakes. Self-centering and energy dissipation in the column were provided by unbonded superelastic nickel–titanium (NiTi) shape memory alloy bars placed inside a plastic hinge element made of rubber. This replaceable plastic hinge was in turn attached to a concrete-filled carbon fiber-reinforced polymer tube and a precast concrete footing that were designed to behave elastically. The proposed concept was evaluated experimentally by testing a ¼-scale column model under simulated near-fault earthquake motions on a shake table. After testing, the model was disassembled, reassembled and tested again. The seismic performance of the reassembled model was found to be comparable to that of the ‘virgin’ model. A relatively simple computational model of the column tested that was developed in OpenSees was able to match some of the key experimental response parameters.

  19. A bridge column with superelastic NiTi SMA and replaceable rubber hinge for earthquake damage mitigation

    NASA Astrophysics Data System (ADS)

    Varela, Sebastian; ‘Saiid' Saiidi, M.

    2016-07-01

    This paper reports a unique concept for resilient bridge columns that can undergo intense earthquake loading and remain functional with minimal damage and residual drift. In this concept, the column is designed so that its components can be easily disassembled and reassembled to facilitate material recycling and component reuse. This is meant to foster sustainability of bridge systems while minimizing monetary losses from earthquakes. Self-centering and energy dissipation in the column were provided by unbonded superelastic nickel-titanium (NiTi) shape memory alloy bars placed inside a plastic hinge element made of rubber. This replaceable plastic hinge was in turn attached to a concrete-filled carbon fiber-reinforced polymer tube and a precast concrete footing that were designed to behave elastically. The proposed concept was evaluated experimentally by testing a ¼-scale column model under simulated near-fault earthquake motions on a shake table. After testing, the model was disassembled, reassembled and tested again. The seismic performance of the reassembled model was found to be comparable to that of the ‘virgin’ model. A relatively simple computational model of the column tested that was developed in OpenSees was able to match some of the key experimental response parameters.

  20. Background carbon monoxide and methane total content: long-term trends and abnormal variations

    NASA Astrophysics Data System (ADS)

    Grechko, Eugeny; Dzhola, Anatoly; Rakitin, Vadim; Shtabkin, Yury

    2015-04-01

    The results of regular ground-based spectroscopic measurements of CO and CH4 atmospheric total content (TC) in Zvenigorod (ZSS station, Moscow region, 53 km toward west from the center of Moscow), the station ZOTTO (Central Siberia) and in Beijing. For ZSS the longest in the world measuring data-set of these impurities TC (from 1970 to present) were analyzed. Several characteristic periods of interannual variations of total CO at ZSS are highlighted: an increase in the 70-80s of last century (1.8%/year), the stabilization in the 80s and a significant decrease since 2001 (2.5%/ year). Moscow's influence leads to a 10% increase in background CO columns only in 5 % cases of all ZSS measurements number. A method for calculating the average seasonal variation of background CO, taking into account factors of atmospheric pollution transportation from industrial regions. CH4 content on ZSS was increasing during 1974-2014 with the rate 0.5 % / year. For the district of Beijing-site, which has no measurement of CO at background stations the seasonal CO variations have obtained as minimum measured values. Character, magnitude and the absolute value of these seasonal variations are in good agreement with the same parameters for the Moscow region. Just as in Moscow area, background level of CO in Beijing decreased (1 % /year for the period 2000-2013). Total content of CO during episodes of abnormal disturbances (summer wildfires of 2010 in Moscow region and 2011, 2012 in Central Siberia) exceeded the typical background TC at 2-5 times. Analysis of satellite CO TC (AIRS v.6) for time-period 2007-2014 years had demonstrated insignificant positive CO trend in polar regions of Eurasia.

  1. Comparative internal friction and modulus evolutions in Ni-Ti and Ni-Ti-Cu shape memory alloys

    NASA Astrophysics Data System (ADS)

    Goubaa, K.; Masse, M.; Bouquet, G.

    1992-08-01

    Internal friction and modulus measurements are performed for the purpose of a comparative study between the structural evolutions occurring, under the effect of the temperature, in two kinds of shape memory alloys: Ni-Ti and Ni-Ti-Cu. Modulus evolutions giving information about the changes in the relative percentages of martensitic and B2 high temperature phases, are useful for the determination of “start” and “finish” transformation temperatures. Internal friction measurements, specially sensitive to structural changes occurring on atomic scale, allow the detection of atomic reorganizations preceding or following the transformation: the R-phase occurrence, on cooling or on heating, the reorientation of martensitic variants on heating. The comparison between the internal friction background levels of each alloy reveals the effect of structural instabilities, specific of Ni-Ti-Cu alloys, and which can be associated with the Cu content. Des mesures de frottement intérieur et de module ont été utilisées en vue de comparer les évolutions structurales intervenant, en fonction de la température, dans deux familles d'alliages à mémoire de forme: Ni-Ti et Ni-Ti-Cu. Les variations de module, sensibles aux proportions relatives des phases martensitique et B2 de haute température, s'avèrent très adaptées à la détermination précise des températures de début et de fin de transformation. Le frottement intérieur, quant à lui, donne des renseignements sur des réorganisations se produisant, à l'échelle atomique, avant ou après la transformation martensitique: apparition de la phase-R, réorientation de variantes de martensite, par exemple,. La comparaison des niveaux du fond de frottement intérieur, relatifs à chaque alliage, montre des différences qui peuvent être associées à des instabilités structurales spécifiques de la présence de cuivre dans les allianges Ni-Ti-Cu.

  2. The effect of HWVP feed nitrate and carbonate content on glass redox adjustment

    SciTech Connect

    Wiemers, K.D.

    1996-03-01

    The Hanford Waste Vitrification Plant (HWVP) is being designed for the Department of Energy to immobilize pretreated radioactive high-level waste (HLW) as glass for geological disposal. In the HWVP formic acid will be added to the pretreated HLW prior to vitrification. The formic acid is added to adjust the feed rheology and to provide a reductant which maintains the feed in the melter within an acceptable redox range. This study was conducted to evaluate the effect of nitrate and carbonate concentrations in the pretreated neutralized current acid waste (NCAW) feed on the amount of formic acid required to obtain an acceptable glass redox state in the melter. The glass redox state was measured by the Fe{sup +2}/Fe{sup +3} ratio in the vitrified product.

  3. Carbon exchange in biological soil crust communities under differential temperatures and soil water contents: implications for global change

    USGS Publications Warehouse

    Grote, Edmund E.; Belnap, Jayne; Housman, David C.; Sparks, Jed P.

    2010-01-01

    Biological soil crusts (biocrusts) are an integral part of the soil system in arid regions worldwide, stabilizing soil surfaces, aiding vascular plant establishment, and are significant sources of ecosystem nitrogen and carbon. Hydration and temperature primarily control ecosystem CO2 flux in these systems. Using constructed mesocosms for incubations under controlled laboratory conditions, we examined the effect of temperature (5-35 1C) and water content (WC, 20-100%) on CO2 exchange in light cyanobacterially dominated) and dark cyanobacteria/lichen and moss dominated) biocrusts of the cool Colorado Plateau Desert in Utah and the hot Chihuahuan Desert in New Mexico. In light crusts from both Utah and New Mexico, net photosynthesis was highest at temperatures 430 1C. Net photosynthesis in light crusts from Utah was relatively insensitive to changes in soil moisture. In contrast, light crusts from New Mexico tended to exhibit higher rates of net photosynthesis at higher soil moisture. Dark crusts originating from both sites exhibited the greatest net photosynthesis at intermediate soil water content (40-60%). Declines in net photosynthesis were observed in dark crusts with crusts from Utah showing declines at temperatures 425 1C and those originating from New Mexico showing declines at temperatures 435 1C. Maximum net photosynthesis in all crust types from all locations were strongly influenced by offsets in the optimal temperature and water content for gross photosynthesis compared with dark respiration. Gross photosynthesis tended to be maximized at some intermediate value of temperature and water content and dark respiration tended to increase linearly. The results of this study suggest biocrusts are capable of CO2 exchange under a wide range of conditions. However, significant changes in the magnitude of this exchange should be expected for the temperature and precipitation changes suggested by current climate models.

  4. [Effects of transgenic Bt rice on soil dissolved organic carbon and nitrogen contents and microbiological properties].

    PubMed

    Li, Xiu-Qiang; Chen, Fa-Jun; Liu, Man-Qiang; Hu, Feng

    2012-01-01

    A two-year field experiment (2009 and 2010) was conducted to evaluate the effects of three transgenic Bt rice lines (KMD, HH1, and BtSY63) and their non-Bt lines (XSD, MH63, and SY63) on soil dissolved organic carbon (DOC) and nitrogen (DON) and microbiological properties. All the measured indices changed significantly with sampling time. Comparing with their corresponding non-Bt lines, the test transgenic Bt lines had little effects on the soil DOC, DON, and microbial biomass nitrogen (MBN). The transgenic Bt lines had significant effects on the soil microbial biomass carbon (MBC), basal respiration (BR), and microbial metabolic quotient (qCO2) in certain periods of time in the first year, but no effects in the second year. Among the soils planted with the three non-Bt rice lines, no difference was observed in the DOC, DON, and microbiological properties, whereas in the soil planted with BtSY63, the MBC and BR were significantly higher, but the qCO2 was significantly lower, as compared with those in the soils planted with KMD and HH1. In sum, two years' planting transgenic Bt rice had little effects on the soil DOC, DON, and microbiological properties, but the differences of soil microbiological properties induced by the planting of different transgenic Bt rice lines were larger than those induced by the planting of different non-Bt lines, implying that long term monitoring would help to reveal the effects of transgenic Bt rice on the structure and function of soil ecosystem. PMID:22489485

  5. Wavelength Dependence in the Analysis of Carbon Content in Coal by Nanosecond 266 nm and 1064 nm Laser Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Xiongwei; Wang, Zhe; Fu, Yangting; Li, Zheng; Ni, Weidou

    2015-08-01

    The wavelength dependence of laser induced breakdown spectroscopy (LIBS) in the analysis of the carbon contents of coal was studied using 266 nm and 1064 nm laser radiations. Compared with the 1064 nm wavelength laser ablation, the 266 nm wavelength laser ablation has less thermal effects, resulting in a better crater morphology on the coal pellets. Besides, the 266 nm wavelength laser ablation also provides better laser-sample coupling and less plasma shielding, resulting in a higher carbon line intensity and better signal reproducibility. The carbon contents in the bituminous coal samples have better linearity with the line intensities of atomic carbon measured by the 266 nm wavelength than those measured by the 1064 nm wavelength. The partial least square (PLS) model was established for the quantitative analysis of the carbon content in coal samples by LIBS. The results show that both of the 266 nm and 1064 nm wavelengths are capable of achieving good performance for the quantitative analysis of carbon content in coal using the PLS method. supported by National Natural Science Foundation of China (No. 51276100) and National Basic Research Program of China (973 Program) (No. 2013CB228501)

  6. Effect of Carbon Content on Microstructure and Mechanical Properties of 9 to 12 pct Cr Ferritic/Martensitic Heat-Resistant Steels

    NASA Astrophysics Data System (ADS)

    Yin, Feng-Shi; Tian, Li-Qian; Xue, Bing; Jiang, Xue-Bo; Zhou, Li

    2012-07-01

    Two heats of 9 to 12 pct Cr ferritic/martensitic heat-resistant steels were prepared. One has an ultralow carbon content of 0.01 wt pct, whereas another heat has a normal carbon content of 0.09 wt pct. The effect of carbon content on microstructure and mechanical properties of 9 to 12 pct Cr ferritic/martensitic heat-resistant steels was studied. The results show that the ultralow-carbon steel contains bimodal, nanosized MX precipitates with high density in the matrix but few M23C6 carbide particles in the normalized-and-tempered state. The smaller nanosized MX precipitates have two kinds of typical morphology: One is cubic and another is rectangular. The cubic MX precipitate contains Nb, Ti, and V, whereas the rectangular one only contains Nb and V. The normal carbon steel has abundant M23C6 carbide particles along the grain and lath boundaries and much less density of nanosized MX precipitates after the same heat treatments. After long-term aging at 923 K (650 °C) for 10,000 hours, the stress rupture properties of the ultralow carbon content steel degrades more significantly. The strength degradation mechanism of the 9 to 12 pct Cr ferritic/martensitic heat-resistant steels is discussed in this article.

  7. Prestressing effect of cold-drawn short NiTi SMA fibres in steel reinforced mortar beams

    NASA Astrophysics Data System (ADS)

    Choi, Eunsoo; Kim, Dong Joo; Hwang, Jin-Ha; Kim, Woo Jin

    2016-08-01

    This study investigated the prestressing effect of cold-drawn short NiTi shape memory alloy (SMA) fibres in steel reinforced mortar beams. The SMA fibres were mixed with 1.5% volume content in a mortar matrix with the compressive strength of 50 MPa. The SMA fibres had an average length of 34 mm, and they were manufactured with a dog-bone shape: the diameters of the end- and middle-parts were 1.024 and 1.0 mm, respectively. Twenty mortar beams with the dimensions of 40 mm × 40 mm × 160 mm (B × H × L) were prepared. Two types of tests were conducted. One was to investigate the prestressing effect of the SMA fibres, and the beams with the SMA fibres were heated at the bottom. The other was to assess the bending behaviour of the beams prestressed by the SMA fibres. The SMA fibres induced upward deflection and cracking at the top surface by heating at the bottom; thus, they achieved an obvious prestressing effect. The beams that were prestressed by the SMA fibres did not show a significant difference in bending behaviour from that of the SMA fibre reinforced beams that were not subjected to heating. Stress analysis of the beams indicated that the prestressing effect decreased in relation to the cooling temperature.

  8. Respiratory Effects of Inhaled Single-Walled Carbon Nanotubes: The Role of Particle Morphology and Iron Content

    NASA Astrophysics Data System (ADS)

    Madl, Amy Kathleen

    Nanotechnology provides promise for significant advancements in a number of different fields including imaging, electronics, and therapeutics. With worldwide production of carbon nanotubes (CNTs) exceeding over 500 metric tons annually and industry growth expecting to double over the next 5 yr, there are concerns our understanding of the hazards of these nanomaterials may not be keeping pace with market demand. The physicochemical properties of CNTs may delineate the key features that determine either toxicity or biocompatibility and assist in evaluating the potential health risks posed in industrial and consumer product settings. We hypothesized that the iron content and morphology of inhaled single-walled carbon nanotubes (SWCNTs) influences the extent of cellular injury and alters homeostasis in the lung. To address this hypothesis, (1) an aerosol system was developed to deliver carbon-based nanomaterials in a manner of exposure that is physiologically and environmentally relevant (e.g., inhalation), (2) acute (1 d) and subacute (10 d) nose-only inhalation studies to a well-characterized aerosol of iron-containing (FeSWCNT) versus cleaned (iron removed, cSWCNTs) SWCNTs were conducted to evaluate the time-course patterns of possible injury through measurement of markers of cytotoxicity, inflammation, and cellular remodeling/homeostasis, and (3) the effects of SWCNTs were compared to other well-studied materials (e.g. non-fibrous, low-iron content ultrafine carbon black and fibrous, high-iron content, highly persistent, durable and potent carcinogen crocidolite) to offer insights into the relative toxicity of these nanomaterials as well as the possible mechanisms by which the effects occur. Rats (SD) were exposed to either aerosolized SWCNTs (raw FeSWCNT or purified cSWCNT), carbon black (CB), crocidolite, or fresh air via nose-only inhalation. Markers of inflammation and cytotoxicity in lung lavage, mucin in different airway generations, and collagen in the

  9. The soil organic carbon content of anthropogenically altered organic soils effects the dissolved organic matter quality, but not the dissolved organic carbon concentrations

    NASA Astrophysics Data System (ADS)

    Frank, Stefan; Tiemeyer, Bärbel; Bechtold, Michel; Lücke, Andreas; Bol, Roland

    2016-04-01

    Dissolved organic carbon (DOC) is an important link between terrestrial and aquatic ecosystems. This is especially true for peatlands which usually show high concentrations of DOC due to the high stocks of soil organic carbon (SOC). Most previous studies found that DOC concentrations in the soil solution depend on the SOC content. Thus, one would expect low DOC concentrations in peatlands which have anthropogenically been altered by mixing with sand. Here, we want to show the effect of SOC and groundwater level on the quantity and quality of the dissolved organic matter (DOM). Three sampling sites were installed in a strongly disturbed bog. Two sites differ in SOC (Site A: 48%, Site B: 9%) but show the same mean annual groundwater level of 15 and 18 cm below ground, respectively. The SOC content of site C (11%) is similar to Site B, but the groundwater level is much lower (-31 cm) than at the other two sites. All sites have a similar depth of the organic horizon (30 cm) and the same land-use (low-intensity sheep grazing). Over two years, the soil solution was sampled bi-weekly in three depths (15, 30 and 60 cm) and three replicates. All samples were analyzed for DOC and selected samples for dissolved organic nitrogen (DON) and delta-13C and delta-15N. Despite differences in SOC and groundwater level, DOC concentrations did not differ significantly (A: 192 ± 62 mg/L, B: 163 ± 55 mg/L and C: 191 ± 97 mg/L). At all sites, DOC concentrations exceed typical values for peatlands by far and emphasize the relevance even of strongly disturbed organic soils for DOC losses. Individual DOC concentrations were controlled by the temperature and the groundwater level over the preceding weeks. Differences in DOM quality were clearer. At site B with a low SOC content, the DOC:DON ratio of the soil solution equals the soil's C:N ratio, but the DOC:DON ratio is much higher than the C:N ratio at site A. In all cases, the DOC:DON ratio strongly correlates with delta-13C. There is no

  10. Inferring brown carbon content from UV aerosol absorption measurements during biomass burning season

    NASA Astrophysics Data System (ADS)

    Mok, J.; Krotkov, N. A.; Arola, A. T.; Torres, O.; Jethva, H. T.; Andrade, M.; Labow, G. J.; Eck, T. F.; Li, Z.; Dickerson, R. R.; Stenchikov, G. L.; Osipov, S.

    2015-12-01

    Measuring spectral dependence of light absorption by colored organic or "brown" carbon (BrC) is important, because of its effects on photolysis rates of ozone and surface ultraviolet (UV) radiation. Enhanced UV spectral absorption by BrC can in turn be exploited for simultaneous retrievals of BrC and black carbon (BC) column amounts in field campaigns. We present an innovative ground-based retrieval of BC and BrC volume fractions and their mass absorption efficiencies during the biomass burning season in Santa Cruz, Bolivia in September-October 2007. Our method combines retrieval of BC volume fraction using AERONET inversion in visible wavelengths with the inversion of total BC+BrC absorption (i.e., column effective imaginary refractive index, kmeas) using Diffuse/Direct irradiance measurements in UV wavelengths. First, we retrieve BrC volume fraction by fitting kmeas at 368nm using Maxwell-Garnett (MG) mixing rules assuming: (1) flat spectral dependence of kBC, (2) known value of kBrC at 368nm from laboratory absorption measurements or smoke chamber experiments, and (3) known BC volume fraction from AERONET inversion. Next, we derive kBrC in short UVB wavelengths by fitting kmeas at 305nm, 311nm, 317nm, 325nm, and 332nm using MG mixing rules and fixed volume fractions of BC and BrC. Our retrievals show larger than expected spectral dependence of kBrC in UVB wavelengths, implying reduced surface UVB irradiance and inhibited photolysis rates of surface ozone destruction. We use a one-dimensional chemical box model to show that the observed strong wavelength dependence of BrC absorption leads to inhibited photolysis of ozone to O(1D), a loss mechanism, while having little impact or even accelerating photolysis of NO2, an ozone production mechanism. Although BC only absorption in biomass burning aerosols is important for climate radiative forcing in the visible wavelengths, additional absorption by BrC is important because of its impact on surface UVB radiation

  11. Formation of microporous NiTi by transient liquid phase sintering of elemental powders.

    PubMed

    Ismail, Muhammad Hussain; Goodall, Russell; Davies, Hywel A; Todd, Iain

    2012-08-01

    Porous metallic structures are attractive for biomedical implant applications as their open porosity simultaneously improves the degree of fixation and decreases the mismatch in stiffness between bone and implant, improving bonding and reducing stress-shielding effects respectively. NiTi alloys exhibit both the shape memory effect and pseudoelasticity, and are of particular interest, though they pose substantial problems in their processing. This is because the shape memory and pseudoelastic behaviours are exceptionally sensitive to the presence of oxygen, and other minor changes in alloy chemistry. Thus in processing careful control of composition and contamination is vital. In this communication, we investigate these issues in a novel technique for producing porous NiTi parts via transient liquid phase sintering following metal injection moulding (MIM) of elemental Ni and Ti powders, and report a new mechanism for pore formation in the powder processing of metallic materials from elemental powders.

  12. Thin film NiTi coatings on optical fiber Bragg sensors

    SciTech Connect

    Mohanchandra, K. P.; Karnani, S.; Emmons, M. C.; Carman, G. P.; Richards, W. L.

    2008-07-21

    This paper describes the sputter deposition and characterization of nickel titanium (NiTi) thin film shape memory alloy onto the surface of an optical fiber Bragg grating. The NiTi coating uniformity, crystallinity, and transformation temperatures are measured using scanning electron microscope, x-ray diffraction, and differential scanning calorimeter, respectively. The strain in the optical fiber is measured using centroid calculation of wavelength shifts. Results show distinct and abrupt changes in the optical fiber signal with the four related transformation temperatures represented by the austenite-martensite forward and reverse phase transformations. These tests demonstrate a coupling present between optical energy and thermal energy, i.e., a modified multiferroic material.

  13. Processing of low carbon content interstellar ice analogues by cosmic rays: implications for the chemistry around oxygen-rich stars

    NASA Astrophysics Data System (ADS)

    de Barros, A. L. F.; da Silveira, E. F.; Pilling, S.; Domaracka, A.; Rothard, H.; Boduch, P.

    2014-03-01

    Radiolysis of a homogeneous H2O:H2CO:CH3OH (100:2:0.8) ice mixture by fast heavy ions is performed in the laboratory in an attempt to simulate the interaction of cosmic rays with frozen surfaces at 15 K. Bombarded by 220-MeV 16O7 + ions, the ice layer is thin enough to be traversed by projectiles at approximately constant velocity and with charge states close to the equilibrium one. Analysis by Fourier transform infrared spectroscopy (FTIR) reveals that the molecular species formed are CH4, CO2, CO, HCO, HCOO- and CH3OCHO. The formation and dissociation cross-sections of all observed daughter molecules are determined. As a control procedure, a carbon budget is performed as the beam fluence increases. The observed radiation effects lead to a general observation that the destruction cross-sections of condensed gases by heavy ions are ruled by a power law that is a function of the electronic stopping power: σd ˜ Sn_e, where n is approximately 3/2. This relation is observed for the destruction of precursor H2CO molecules and for the formation of daughter species. The present results help our understanding of the chemical and physicochemical interactions induced by heavy cosmic rays in cold astrophysical environments with low carbon contents, such as those around oxygen-rich stars.

  14. Surface ultrastructure and mechanical properties of three different white-coated NiTi archwires.

    PubMed

    Ryu, Seong-Hee; Lim, Byung-Suh; Kwak, Eun Joo; Lee, Gi-Ja; Choi, Samjin; Park, Ki-Ho

    2015-01-01

    The recent trend in orthodontic treatment is to apply esthetic materials to orthodontic appliances with adequate clinical performance. The aim of this study was to investigate the ultrastructure (surface roughness) and mechanical properties (load-deflection curve) of three as-received, white-coated superelastic nickel-titanium (NiTi) archwires using atomic force microscopy (AFM) and modified three-point bending test assessments, respectively. Three representative esthetic NiTi archwires were used, silver-platinum- and polymer-coated NiTi Natural Dany (Dany group), epoxy resin-coated Orthoforce Ultraesthetic™ (Ultra group), and Teflon®-coated Perfect (Perfect group). Uncoated metallic areas of each wire were used as controls. The diameter of the Perfect archwire was significantly larger than that of other archwires. The Dany and Ultra groups showed more deflection than the Perfect group. The hysteresis area of the Dany and Ultra groups showed approximately two- and fourfold increases compared to the control and the Perfect group. The Dany group (2037.5 ± 527.3 nm) had the highest peak-to-peak surface roughness in the coated areas, followed by the Ultra group (811.1 ± 407.5 nm) and the Perfect group (362.7 ± 195.8 nm). However, reverse nanostructural changes in the surface roughness were observed in the uncoated metallic areas. The results suggested that the load-deflection properties and the surface roughness of superelastic NiTi archwires were affected directly by the coating materials. Although the efficiency of orthodontic treatment was affected by various factors, when only considering the frictional force and mechanostructural properties, the epoxy resin-coated Orthoforce Ultraesthetic™ archwires were the most effective for orthodontic treatment.

  15. Superelastic NiTi springs for corrective skull operations in children with craniosynostosis.

    PubMed

    Morawiec, H Z; Lekston, Z H; Kobus, K F; Wegrzyn, M C; Drugacz, J T

    2007-09-01

    This paper concerns the formation and characterization of superelastic springs and rings of NiTi alloys for long-term skull correction. Superelastic properties of the rings were induced in the process of ageing of the already formed rings which cause hardening of parent phase by the precipitation of coherent Ni(4)Ti(3) particles. The efficacy of the worked out springs and rings were successfully proved in several clinical applications. PMID:17483902

  16. Economical, Efficient, Simple Device for Controlled Annealing NiTi Archwire

    PubMed Central

    Chitko, S.S.; Kerudi, Veerendra V.; Patil, Neeraj S.; Tekale, Pawankumar Dnyandeo

    2015-01-01

    In fixed orthodontic treatment, for the cinch back purpose, there is need of annealing of distal end of NiTi arch wire. During this procedure the area or length to be annealed is difficult to control. This inappropriate heating leads to deleterious effect on property of the wire. To prevent this problem a simple economical and efficient device was prepared that prevents annealing of excessive length of wire and thus prevents the deterioration of wire required for appropriate action. PMID:26436067

  17. An experimental investigation into the role of phyllosilicate content on earthquake propagation during seismic slip in carbonate faults

    NASA Astrophysics Data System (ADS)

    Bullock, Rachael J.; De Paola, Nicola; Holdsworth, Robert E.

    2015-05-01

    Carbonate faults commonly contain small amounts of phyllosilicate in their slip zones, due to pressure solution and/or clay smear. To assess the effect of phyllosilicate content on earthquake propagation in carbonate faults, friction experiments were performed at 1.3 m/s on end-members and mixtures of calcite, illite-smectite, and smectite gouge. Experiments were performed at 9 MPa normal load, under room humidity and water-saturated conditions. All dry gouges show initial friction values (μi) of 0.51-0.58, followed by slip hardening to peak values of 0.61-0.76. Slip weakening then ensues, with friction decreasing to steady state values (μss) of 0.19-0.33 within 0.17-0.58 m of slip. Contrastingly, wet gouges containing 10-50 wt % phyllosilicate exhibit μi values between 0.07 and 0.52 followed by negligible or no slip hardening; rather, steady state sliding (μss ≪ 0.2) is attained almost immediately. Microstructurally, dry gouges show intense cataclasis and wear within localized principal slip zones, plus evidence for thermal decomposition of calcite. Wet gouges exhibit distributed deformation, less intense cataclasis, and no evidence of thermal decomposition. It is proposed that in wet gouges, slip is distributed across a network of weak phyllosilicate formed during axial loading compaction prior to shear. This explains the (1) subdued cataclasis and associated lack of slip hardening, (2) distributed nature of deformation, and (3) lack of evidence for thermal decomposition, due to low friction and lack of slip localization. These findings imply that just 10% phyllosilicate in the slip zone of fluid-saturated carbonate faults can (1) dramatically change their frictional behavior, facilitating rupture propagation to the surface, and (2) significantly lower frictional heating, preventing development of microscale seismic markers.

  18. Assessment of the Impact of Climate Change and Land Management Change on Soil Organic Carbon Content, Leached Carbon Rates and Dissolved Organic Carbon Concentrations

    NASA Astrophysics Data System (ADS)

    Stergiadi, Maria; de Nijs, Ton; van der Perk, Marcel; Bonten, Luc

    2014-05-01

    Climate change is projected to significantly affect the concentrations and mobility of contaminants, such as metals and pathogens, in soil, groundwater and surface water. Climate- and land management-induced changes in soil organic carbon and dissolved organic carbon levels may promote the transport of toxic substances, such as copper and cadmium, and pathogenic microorganisms, ultimately affecting the exposure of humans and ecosystems to these contaminants. In this study, we adopted the Century model to simulate past (1900 - 2010), present, and future (2010 - 2100) SOC and DOC levels for a sandy and a loamy soil typical for Central and Western European conditions under three land use types (forest, grassland and arable land) and several future scenarios addressing climate change and land management change. The climate scenarios were based on the KNMI'06 G+ and W+ scenarios from the Royal Dutch Meteorological Institute. The simulated current SOC levels were compared to observed SOC values derived from various Dutch soil databases, taking into account the different soil depths the simulated and observed values refer to. The simulated SOC levels were generally in line with the observed values for the different kinds of soil and land use types. Climate change scenarios resulted in a decrease in both SOC and DOC for the grassland systems, whereas in the arable land (on sandy soil) and in the forest systems, SOC was found to increase and DOC to decrease. A sensitivity analysis of the individual effects of changes in temperature and precipitation showed that the effect of temperature predominates over the effect of precipitation. A reduction in the application rates of artificial fertilizers leads to a decrease in the SOC stocks and the leached carbon rates in the arable land systems, but has a negligible effect on SOC and DOC levels of the grassland systems. This study demonstrated the ability of the Century model to simulate climate change and agricultural management

  19. 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.

  20. Visible and near infrared reflectance spectroscopy as a tool to monitor in situ soil organic carbon content.

    NASA Astrophysics Data System (ADS)

    Noon, C.; Stevens, A.; van Wesemael, B.

    2012-04-01

    The demand for up-to-date soil information has driven the development of rapid techniques to determine soil properties such as soil organic carbon (SOC) in situ. Proximally sensed diffuse reflectance has produced promising results. However, large scale applications are difficult to develop because the relationship between spectral data and soil properties depend on soil type and therefore is inherently local. This study aims to generate robust and locally-relevant calibration models that are applicable to a large scale database in order to provide accurate measures of SOC content in Belgian agricultural land. We collected more than 400 soil samples in South of Belgium covering 6 out 14 agro-ecological zones of the country. Soil samples were spectrally measured in laboratory with an ASD FieldSpec Pro spectroradiometer. By means of cluster analysis of the spectral library linked with several soil attributes (geographical locations, soil types, etc.) multivariate calibration models were built for each identified cluster. Based on their spectral characteristics and easy-obtainable soil attributes, these local calibration models will allow to determine the SOC content of unknown soil samples at large scales.

  1. Three-dimensional porous carbon composites containing high sulfur nanoparticle content for high-performance lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Li, Guoxing; Sun, Jinhua; Hou, Wenpeng; Jiang, Shidong; Huang, Yong; Geng, Jianxin

    2016-02-01

    Sulfur is a promising cathode material for lithium-sulfur batteries because of its high theoretical capacity (1,675 mA h g-1) however, its low electrical conductivity and the instability of sulfur-based electrodes limit its practical application. Here we report a facile in situ method for preparing three-dimensional porous graphitic carbon composites containing sulfur nanoparticles (3D S@PGC). With this strategy, the sulfur content of the composites can be tuned to a high level (up to 90 wt%). Because of the high sulfur content, the nanoscale distribution of the sulfur particles, and the covalent bonding between the sulfur and the PGC, the developed 3D S@PGC cathodes exhibit excellent performance, with a high sulfur utilization, high specific capacity (1,382, 1,242 and 1,115 mA h g-1 at 0.5, 1 and 2 C, respectively), long cycling life (small capacity decay of 0.039% per cycle over 1,000 cycles at 2 C) and excellent rate capability at a high charge/discharge current.

  2. Three-dimensional porous carbon composites containing high sulfur nanoparticle content for high-performance lithium–sulfur batteries

    PubMed Central

    Li, Guoxing; Sun, Jinhua; Hou, Wenpeng; Jiang, Shidong; Huang, Yong; Geng, Jianxin

    2016-01-01

    Sulfur is a promising cathode material for lithium–sulfur batteries because of its high theoretical capacity (1,675 mA h g−1); however, its low electrical conductivity and the instability of sulfur-based electrodes limit its practical application. Here we report a facile in situ method for preparing three-dimensional porous graphitic carbon composites containing sulfur nanoparticles (3D S@PGC). With this strategy, the sulfur content of the composites can be tuned to a high level (up to 90 wt%). Because of the high sulfur content, the nanoscale distribution of the sulfur particles, and the covalent bonding between the sulfur and the PGC, the developed 3D S@PGC cathodes exhibit excellent performance, with a high sulfur utilization, high specific capacity (1,382, 1,242 and 1,115 mA h g−1 at 0.5, 1 and 2 C, respectively), long cycling life (small capacity decay of 0.039% per cycle over 1,000 cycles at 2 C) and excellent rate capability at a high charge/discharge current. PMID:26830732

  3. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires.

    PubMed

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-01-01

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19' martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19' martensitic transformation, and (V) plastic deformation of the specimen. PMID:27049025

  4. Automated detection of a prostate Ni-Ti stent in electronic portal images

    SciTech Connect

    Carl, Jesper; Nielsen, Henning; Nielsen, Jane; Lund, Bente; Larsen, Erik Hoejkjaer

    2006-12-15

    Planning target volumes (PTV) in fractionated radiotherapy still have to be outlined with wide margins to the clinical target volume due to uncertainties arising from daily shift of the prostate position. A recently proposed new method of visualization of the prostate is based on insertion of a thermo-expandable Ni-Ti stent. The current study proposes a new detection algorithm for automated detection of the Ni-Ti stent in electronic portal images. The algorithm is based on the Ni-Ti stent having a cylindrical shape with a fixed diameter, which was used as the basis for an automated detection algorithm. The automated method uses enhancement of lines combined with a grayscale morphology operation that looks for enhanced pixels separated with a distance similar to the diameter of the stent. The images in this study are all from prostate cancer patients treated with radiotherapy in a previous study. Images of a stent inserted in a humanoid phantom demonstrated a localization accuracy of 0.4-0.7 mm which equals the pixel size in the image. The automated detection of the stent was compared to manual detection in 71 pairs of orthogonal images taken in nine patients. The algorithm was successful in 67 of 71 pairs of images. The method is fast, has a high success rate, good accuracy, and has a potential for unsupervised localization of the prostate before radiotherapy, which would enable automated repositioning before treatment and allow for the use of very tight PTV margins.

  5. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires

    PubMed Central

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-01-01

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19′ martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19′ martensitic transformation, and (V) plastic deformation of the specimen. PMID:27049025

  6. Superelastic NiTi thin film small vessel graft for vascular repair

    NASA Astrophysics Data System (ADS)

    Chun, Youngjae; Levi, Daniel S.; Mohanchandra, K. P.; Vinuela, Fernando; Vinuela, Fernando, Jr.; Carman, Gregory P.

    2009-03-01

    Thin film NiTi produced by sputter deposition was used in the design of small vessel grafts intended to treat small vessel aneurysms. Thin film small vessel grafts were fabricated by "hot-target" DC sputter deposition. Both stress-strain curves and DSC curves were generated for the film used to fabricate small vessel grafts. The films used for small vessel grafts had an Af temperatures of approximately 36 degrees allowing for body activated response from a micro-catheter. Thin film small vessel grafts were tested in a pulsatile flow loop in vitro. Small vessel grafts could be compressed into and easily delivery in < 3 Fr catheters. Theoretical frictional and wall drag forces on a thin film NiTi small vessel vascular graft were calculated and the radial force exerted by thin film small vessel grafts was evaluated theoretically and experimentally. In-vivo studies in swine confirmed that thin film NiTi small vessel grafts could be deployed accurately and consistently in the swine vascular system.

  7. Computational Modeling to Predict Fatigue Behavior of NiTi Stents: What Do We Need?

    PubMed Central

    Dordoni, Elena; Petrini, Lorenza; Wu, Wei; Migliavacca, Francesco; Dubini, Gabriele; Pennati, Giancarlo

    2015-01-01

    NiTi (nickel-titanium) stents are nowadays commonly used for the percutaneous treatment of peripheral arterial disease. However, their effectiveness is still debated in the clinical field. In fact a peculiar cyclic biomechanical environment is created before and after stent implantation, with the risk of device fatigue failure. An accurate study of the device fatigue behavior is of primary importance to ensure a successful stenting procedure. Regulatory authorities recognize the possibility of performing computational analyses instead of experimental tests for the assessment of medical devices. However, confidence in numerical methods is only possible after verification and validation of the models used. For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process. Hence, special attention should be paid to the accuracy of the description of the device geometry and the material properties implementation into the numerical code, as well as to the definition of the fatigue limit. In this paper, a path for setting up an effective numerical model for NiTi stent fatigue assessment is proposed and the results of its application in a specific case study are illustrated. PMID:26011245

  8. An original architectured NiTi silicone rubber structure for biomedical applications.

    PubMed

    Rey, T; Le Cam, J-B; Chagnon, G; Favier, D; Rebouah, M; Razan, F; Robin, E; Didier, P; Heller, L; Faure, S; Janouchova, K

    2014-12-01

    This paper deals with composite structures for biomedical applications. For this purpose, an architectured tubular structure composed of Nickel Titanium (NiTi) Shape Memory Alloy (SMA) and silicone rubber was fabricated. One of the main interests of such structures is to ensure a good adhesion between its two constitutive materials. A previous study of the authors (Rey et al., 2014) has shown that the adhesion between NiTi and silicone rubber can be improved by an adhesion promoter or plasma treatment. However, adhesion promoters are often not biocompatible. Hence, plasma treatment is favored to be used in the present study. Three different gases were tested; air, argon and oxygen. The effects of these treatments on the maximum force required to pull-out a NiTi wire from the silicone rubber matrix were investigated by means of pull-out tests carried out with a self-developed device. Among the three gases, a higher maximum force was obtained for argon gas in the plasma treatment. A tube shaped architectured NiTi/silicone rubber structure was then produced using this treatment. The composite was tested by means of a bulge test. Results open a new way of investigations for architectured NiTi-silicone structures for biomechanical applications.

  9. Effects of hot working on the martensitic transformation of Ni-Ti alloy

    SciTech Connect

    Render Jean; Jongcheng Tsai . Materials Research Lab.)

    1994-04-15

    Among shape memory alloys, Ni-Ti alloys of near-equiatomic composition have been used for various commercial applications, since they have good mechanical properties and well-known shape memory effects. Processing disadvantages, however, include the difficulties and expenses of processing. Moreover, cold working to high reduction is difficult and expensive because limited cold workability and high work hardening, makes hot working indispensable. Therefore, optimization of hot working parameters and control of shape memory behavior is necessary. It is generally known that the influence of work hardening and subsequent isothermal annealing on the stability of the individual phases formed in Ni-Ti shape memory alloys has been investigated. Work hardening promotes the formation of the rhombohedral R phase. The matrix work hardening suppresses the phase transformation B2[leftrightarrow]B19[prime]. In this study, the equiatomic Ni-Ti alloy is plastic deformed by hot compression at various temperatures. The effects of hot compression on the martensitic transformation are investigated with differential scanning calorimeter measurements and hardness tests. The optimal hot working temperature range is also discussed.

  10. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires.

    PubMed

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-04-06

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19' martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19' martensitic transformation, and (V) plastic deformation of the specimen.

  11. Ab Initio Simulations of Temperature Dependent Phase Stability and Martensitic Transitions in NiTi

    NASA Technical Reports Server (NTRS)

    Haskins, Justin B.; Thompson, Alexander E.; Lawson, John W.

    2016-01-01

    For NiTi based alloys, the shape memory effect is governed by a transition from a low-temperature martensite phase to a high-temperature austenite phase. Despite considerable experimental and computational work, basic questions regarding the stability of the phases and the martensitic phase transition remain unclear even for the simple case of binary, equiatomic NiTi. We perform ab initio molecular dynamics simulations to describe the temperature-dependent behavior of NiTi and resolve several of these outstanding issues. Structural correlation functions and finite temperature phonon spectra are evaluated to determine phase stability. In particular, we show that finite temperature, entropic effects stabilize the experimentally observed martensite (B19') and austenite (B2) phases while destabilizing the theoretically predicted (B33) phase. Free energy computations based on ab initio thermodynamic integration confirm these results and permit estimates of the transition temperature between the phases. In addition to the martensitic phase transition, we predict a new transition between the B33 and B19' phases. The role of defects in suppressing these phase transformations is discussed.

  12. Behavior of NiTi Wires for Dampers and Actuators in Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Isalgue, A.; Auguet, C.; Grau, R.; Torra, V.; Cinca, N.; Fernandez, J.

    2015-09-01

    Shape memory alloys are considered smart materials because of their singular thermo-mechanical properties, due to a thermoelastic martensitic transformation, enabling possible uses as actuators (because of mechanical recovery induced from temperature changes) and as dampers (because of hysteresis). NiTi wires for dampers in Civil Engineering had been characterized and tested in facilities. Guaranteed performance needs to know behavior during fatigue life and knowledge of effects in the event of extreme conditions, as eventual overstraining. In this work, we check the possibilities to absorb mechanical energy on the fatigue life depending on stress level and explore the consequences of overstraining the material during installation, the possibilities of partial healing by moderate heating, and some effects of over-stressing the wires. The mechanical energy absorbed by the unit weight of damper wire might be very high during its lifetime if maximum stresses remain relatively low allowing high fatigue life. We show also some results on NiTi wire working as an actuator. The lifetime mechanical work performed by an actuator wire can be very high if applied stresses are limited. The overstraining produces relevant "residual" deformation, which can be to some extent reversed by moderate heating at zero stress. The reason for the observed characteristics seems to be that when external high stresses are applied to an NiTi wire, it undergoes some plastic deformation, leaving a distribution of internal stresses that alter the shape and position of the macroscopic stress-strain transformation path.

  13. Effect of quartz content on the physical and structural properties of carbonate rocks from Perlis, Malaysia

    NASA Astrophysics Data System (ADS)

    Mustafa, T. N. A. S. Tengku; Munusamy, S. R. R.; Lan, D. N. Uy; Yunos, N. F. M.

    2016-07-01

    This paper presents on the structural changes associated with mechanical activation of limestone (CaCO3) and dolomite (CaMg(CO3)2) from Perlis, Malaysia via Planetary ball milling. Operational variables include 3 level of revolution speed (250, 350 and 450 rpm), grinding durations (30, 60 and 90 min) and ball to powder ratios BPR (3:1. 6:1 and 9:1) respectively. The chemical compositions of both mineral samples were determined with XRF technique while the structural properties and morphological characteristics identified using XRD and SEM methods. The structural changes such as amorphization, decline in crystallite size (CS), degree of crystallinity (DOC) and morphological alterations are closely related to the operational parameter and the mineral constituents such as quartz content. Overall, the crystallite size of limestone and dolomite ranges from 60.74 to 25.15 nm and 45.65 to 22.07 nm respectively. Accordingly the DOC was reduced from 100 to 31.69% in CaCO3 and 36.55% in (CaMg(CO3)2).

  14. Use of phosphoranimines to reduce organic carbonate content in Li-ion battery electrolytes

    DOE PAGES

    Dufek, Eric J.; Klaehn, John R.; McNally, Joshua S.; Rollins, Harry W.; Jamison, David K.

    2016-05-09

    In this study, the use of phosphoranimines (PAs), a class of linear, monomeric phosphazenes, as electrolytes for Li-ion battery applications has been investigated as a route to improve safety and stability for Li-ion batteries. Of the potential PAs for use in battery applications, this work focuses on the initial synthetic preparation and analysis of N-trimethylsilyl-P,P-bis((2-methoxyethoxy)ethoxy)-P-ethylphosphoranimine (PA-5). PA-5 has high LiPF6 solubility in excess of 2 M, high thermal stability with a melting point below -80°C and high thermal stability as a neat compound to at least 250°C. As part of electrolyte blends, the inclusion of PA-5 shifts the onset ofmore » thermal degradation by close to 40°C at 35% loading and by 20°C at a 10% loading, improves the low temperature performance of the electrolyte, and when used as a primary solvent leads to increases in the flash point (by 20°C) when compared to more traditional EC:EMC blends. Cycling capabilities of full-coin cells with graphite negative electrodes and Li1+w[Ni0.5Mn0.3Co0.2]1-wO2 positive electrodes using PA-5:EC:EMC electrolyte blends are comparable with the performance seen for traditional EC:EMC blends. Analysis of the impact of the use of additives such as vinylene carbonate in PA-5:EC:EMC blended electrolyte results in enhanced capacity retention and improved coulombic efficiency.« less

  15. Influence of carbon content on the copper-telluride phase formation and on the resistive switching behavior of carbon alloyed Cu-Te conductive bridge random access memory cells

    SciTech Connect

    Devulder, Wouter De Schutter, Bob; Detavernier, Christophe; Opsomer, Karl; Franquet, Alexis; Meersschaut, Johan; Muller, Robert; Van Elshocht, Sven; Jurczak, Malgorzata; Goux, Ludovic; Belmonte, Attilio

    2014-02-07

    In this paper, we investigate the influence of the carbon content on the Cu-Te phase formation and on the resistive switching behavior in carbon alloyed Cu{sub 0.6}Te{sub 0.4} based conductive bridge random access memory (CBRAM) cells. Carbon alloying of copper-tellurium inhibits the crystallization, while attractive switching behavior is preserved when using the material as Cu-supply layer in CBRAM cells. The phase formation is first investigated in a combinatorial way. With increasing carbon content, an enlargement of the temperature window in which the material stays amorphous was observed. Moreover, if crystalline phases are formed, subsequent phase transformations are inhibited. The electrical switching behavior of memory cells with different carbon contents is then investigated by implementing them in 580 μm diameter dot TiN/Cu{sub 0.6}Te{sub 0.4}-C/Al{sub 2}O{sub 3}/Si memory cells. Reliable switching behavior is observed for carbon contents up to 40 at. %, with a resistive window of more than 2 orders of magnitude, whereas for 50 at. % carbon, a higher current in the off state and only a small resistive window are present after repeated cycling. This degradation can be ascribed to the higher thermal and lower drift contribution to the reset operation due to a lower Cu affinity towards the supply layer, leading cycle-after-cycle to an increasing amount of Cu in the switching layer, which contributes to the current. The thermal diffusion of Cu into Al{sub 2}O{sub 3} under annealing also gives an indication of the Cu affinity of the source layer. Time of flight secondary ion mass spectroscopy was used to investigate this migration depth in Al{sub 2}O{sub 3} before and after annealing, showing a higher Cu, Te, and C migration for high carbon contents.

  16. [Effects of nitrogen application on soil greenhouse gas fluxes in Eucalyptus plantations with different soil organic carbon content].

    PubMed

    Li, Rui-Da; Zhang, Kai; Su, Dan; Lu, Fei; Wan, Wu-Xing; Wang, Xiao-Ke; Zheng, Hua

    2014-10-01

    The effects of nitrogen fertilization or nitrogen deposition on soil greenhouse gases fluxes has been well studied, while little has been piloted about the effects of nitrogen application on soil greenhouse gas fluxes and its discrepancy with different soil organic carbon content. In our study, we conducted field control experiment in a young Eucalyptus plantation in Southeast China. We compared the effects of 4 levels of nitrogen fertilization (Control: 0 kg · hm(-2); Low N: 84.2 kg · hm(-2); Medium N: 166.8 kg · hm(-2); High N: 333.7 kg · hm(-2)) on soil GHGs fluxes from 2 sites (LC and HC) with significantly different soil organic carbon (SOC) content (P < 0.05). The results showed: (1) Fertilization had significant priming effect on CO2 and N2O emission fluxes. One month after fertilization, both CO2 and N2O had the flux peak and decreased gradually, and the difference among the treatments disappeared at the end of the growing season. However, fertilization had no significant effect on CH4 oxidation between the 2 sites. (2) Fertilization and SOC were two crucial factors that had significant effects on CO2 and N2O emission. Fertilization had a significant positive effect on CO2 and N2O emission fluxes (P < 0.001). CH4 oxidation rates decreased with the increasing N addition, but there was no statistical difference (P > 0.05). The CO2 and N2O emission fluxes were significantly higher in HC than those in LC (P < 0.01). (3) Fertilization and SOC had great interactive effect on CO2 and N2O emission (P < 0.05). Compared with fluxes in LC, the fluxes in HC were much more sensitive to N input: low N could remarkably stimulate the CO2 and N2O emission. In conclusion, the effects of nitrogen fertilization on soil GHGs fluxes were not only in connection with the intensify of nitrogen, but also closely tied to the SOC content. When we assess the effects of nitrogen on soil GHGs fluxes, the difference induced by SOC should not be ignored.

  17. Comparative study on growth, yield and carbon content in Pongamia pinnata under water stress and urea supplementation.

    PubMed

    Saraswathi, S Gnaana; Ezhilarasi, S

    2012-05-01

    The growth, yield, and carbon content of eight-month old seedlings of Pongamia pinnata were compared under water and urea supplementation. One set of plants were subjected to water stress condition (WS), whereas the other supplied with 2 g of urea (WS+U) under WS. Both the experimental set ups were exposed to varying treatment levels which include full irrigation (100%, control) followed by 75% (T1), 50% (T2), 25% (T3) and 12.5% (T4). The growth, leaf area and relative water content were maximum under WS when compared to WS+U (p < 0.001). The maximum biomass was produced in the seedlings under WS in control (1.68 g) followed by T1 (1.38 g), T2 (1.53 g), T3 (0.93 g) and T4 (0.73 g). A significant (p < 0.001) reduction in biomass production was observed in WS+U in control (1.28 g), T1 (0.66 g), T2 (1.13 g) and T3 (0.44 g). T4 of WS+U showed similar biomass (0.73 g) as that of T4 of WS. Under WS, the highest biomass allocation was recorded in shoots followed by leaves and roots. Similar trend was observed in WS+U. However, the percentage of allocation was more in the roots of WS+U (27.2%) when compared to WS (22.24 %). The highest amount of carbon content was observed in control plants treated under WS (9.59 g) followed by control plants of WS+U (7.31 g) (p < 0.001). The results of the preliminary study clearly indicated that P. pinnata seedlings were able to cope-up with water stress conditions without urea application and can perform well in 50% water availability and is best suited for the plantation programs in the semi-arid ecosystems. PMID:23029906

  18. Carbon and nitrogen contents in particle-size fractions of topsoil along a 3000 km aridity gradient in grasslands of northern China

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Guang; Sistla, Seeta A.; Wang, Xiao-Bo; Lü, Xiao-Tao; Han, Xing-Guo

    2016-06-01

    Climate factors such as aridity significantly influence soil carbon (C) and nitrogen (N) stocks in terrestrial ecosystems. Further, soil texture plays an important role in driving changes of soil C and N contents at regional scale. However, it remains uncertain whether such changes resulted from the variation of different soil particle-size factions and/or the C and N concentrations in those fractions. We examined the distribution of total C and N in both bulk soil and different soil particle-size fractions, including sand (53-2000 µm), silt (2-53 µm), and clay (< 2 µm), along a 3000 km transect in arid and semi-arid grasslands of northern China. Across the whole transect, sand content was positively and silt content was negatively correlated with increasing aridity. Carbon content in bulk soils (0-10 cm) ranged from 4.36 to 46.16 Mg C ha-1, while N content ranged from 0.22 to 4.28 Mg N ha-1 across different sampling sites on the transect. The total C and N concentrations and contents in bulk soils as well as in the three particle-size fractions tended to be negatively correlated with aridity. The concentrations and contents of total C and N in bulk soils were positively correlated with silt and clay contents and negatively correlated with sand content. Positive correlations were observed between the concentrations and contents of C or N in bulk soils and the C or N concentrations in the three soil particle-size fractions. By characterizing such a large scale aridity gradient, our results highlight that aridity would decrease soil C and N contents both by favoring increased sand content and by decreasing C and N concentrations in all the three soil fractions. These patterns thus have significant implications for understanding soil C and N sequestration under scenarios of increasing aridity in global drylands that are predicted to occur this century.

  19. Graphene-containing carbon aerogel prepared using polyethyleneimine (PEl)-modified graphene oxide (GO) for supercapacitor: effect of polyethyleneimine-modified GO content.

    PubMed

    Lee, Yoon Jae; Lee, Joongwon; Kim, Gil-Pyo; Lee, Eo Jin; Yi, Jongheop; Song, In Kyu

    2014-11-01

    Graphene-containing carbon aerogel was prepared by a sol-gel polymerization of resorcinol-formaldehyde (RF) method using polyethyleneimine (PEL)-modified chemically exfoliated graphene oxide (GO), and its electrochemical performance as an electrode for supercapacitor was examined. The effect of PEI-modified GO content on the physicochemical and electrochemical properties of graphene-containing carbon aerogel was investigated. For comparison, graphene-free carbon aerogel was also prepared. Among the samples, graphene-containing carbon aerogel prepared using 45 wt% PEI-modified GO solution (CA(45PG)) showed the highest BET surface area (784 m2/g) and the largest pore volume (1.71 cm3/g) with well-developed porous structure. Electrochemical properties of graphene-containing carbon aerogel and graphene-free carbon aerogel electrodes were measured by cyclic voltammetry, charge/discharge test, and electrochemical impedance spectroscopy in 6 M KOH electrolyte. Various electrochemical measurements revealed that CA(45PG) showed the highest specific capacitance (261 F/g), the lowest equivalent series resistance (0.16 Ω), and superior capacitive behavior. It is concluded that PEI-modified GO content served as an important factor determining the physicochemical properties and supercapacitive electrochemical performance of graphene-containing carbon aerogel.

  20. Mapping within-field variations of soil organic carbon content using UAV multispectral visible near-infrared images

    NASA Astrophysics Data System (ADS)

    Gilliot, Jean-Marc; Vaudour, Emmanuelle; Michelin, Joël

    2016-04-01

    This study was carried out in the framework of the PROSTOCK-Gessol3 project supported by the French Environment and Energy Management Agency (ADEME), the TOSCA-PLEIADES-CO project of the French Space Agency (CNES) and the SOERE PRO network working on environmental impacts of Organic Waste Products recycling on field crops at long time scale. The organic matter is an important soil fertility parameter and previous studies have shown the potential of spectral information measured in the laboratory or directly in the field using field spectro-radiometer or satellite imagery to predict the soil organic carbon (SOC) content. This work proposes a method for a spatial prediction of bare cultivated topsoil SOC content, from Unmanned Aerial Vehicle (UAV) multispectral imagery. An agricultural plot of 13 ha, located in the western region of Paris France, was analysed in April 2013, shortly before sowing while it was still bare soil. Soils comprised haplic luvisols, rendzic cambisols and calcaric or colluvic cambisols. The UAV platform used was a fixed wing provided by Airinov® flying at an altitude of 150m and was equipped with a four channels multispectral visible near-infrared camera MultiSPEC 4C® (550nm, 660nm, 735 nm and 790 nm). Twenty three ground control points (GCP) were sampled within the plot according to soils descriptions. GCP positions were determined with a centimetric DGPS. Different observations and measurements were made synchronously with the drone flight: soil surface description, spectral measurements (with ASD FieldSpec 3® spectroradiometer), roughness measurements by a photogrammetric method. Each of these locations was sampled for both soil standard physico-chemical analysis and soil water content. A Structure From Motion (SFM) processing was done from the UAV imagery to produce a 15 cm resolution multispectral mosaic using the Agisoft Photoscan® software. The SOC content was modelled by partial least squares regression (PLSR) between the

  1. Shape-memory NiTi foams produced by replication of NaCl space-holders.

    PubMed

    Bansiddhi, A; Dunand, D C

    2008-11-01

    NiTi foams were created with a structure (32-36% open pores 70-400 microm in size) and mechanical properties (4-25 GPa stiffness, >1000 MPa compressive strength, >42% compressive ductility, and shape-memory strains up to 4%) useful for bone implant applications. A mixture of NiTi and NaCl powders was hot-isostatically pressed at 950 and 1065 degrees C and the NaCl phase was then dissolved in water. The resulting NiTi foams show interconnected pores that replicate the shape and size of the NaCl powders, indicating that NiTi powders densified significantly before NaCl melted at 801 degrees C. Densifying NiTi or other metal powders above the melting point of the space-holder permits the use of NaCl, with the following advantages compared with higher-melting, solid space-holders such as oxides and fluorides used to date: (i) no temperature limit for densification; (ii) lower cost; (iii) greater flexibility in powder (and thus pore) shape; (iv) faster dissolution; (v) reduced metal corrosion during dissolution; (vi) lower toxicity if space-holder residues remain in the foam.

  2. 60NiTi Intermetallic Material Evaluation for Lightweight and Corrosion Resistant Spherical Sliding Bearings for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Jefferson, Michael

    2015-01-01

    NASA Glenn Research Center and the Kamatics subsidiary of the Kaman Corporation conducted the experimental evaluation of spherical sliding bearings made with 60NiTi inner races. The goal of the project was to assess the feasibility of manufacturing lightweight, corrosion resistant bearings utilizing 60NiTi for aerospace and industrial applications. NASA produced the bearings in collaboration with Abbott Ball Corporation and Kamatics fabricated bearing assemblies utilizing their standard reinforced polymer liner material. The assembled bearings were tested in oscillatory motion at a load of 4.54kN (10,000 lb), according to the requirements of the plain bearing specification SAE AS81820. Several test bearings were exposed to hydraulic fluid or aircraft deicing fluid prior to and during testing. The results show that the 60NiTi bearings exhibit tribological performance comparable to conventional stainless steel (440C) bearings. Further, exposure of 60NiTi bearings to the contaminant fluids had no apparent performance effect. It is concluded that 60NiTi is a feasible bearing material for aerospace and industrial spherical bearing applications.

  3. The Influence of Surface Nanocrystallization Induced by Shot Peening on Corrosion Behavior of NiTi Alloy

    NASA Astrophysics Data System (ADS)

    Olumi, S.; Sadrnezhaad, S. K.; Atai, M.

    2015-08-01

    Nickel-titanium (NiTi) shape memory alloys have been widely used as implant materials, due to their superior shape memory properties and similar mechanical behavior to bone tissue. The presence of nickel on the surface of nickel-titanium alloy and release of this ion in the body environment will result in some allergic reactions. In current study, we used shot pinning process to produce nanocrystalline nickel-titanium alloy with increased corrosion resistance. Field emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD) analysis, and atomic force microscopy were employed to investigate the surface features of samples. The quantitative chemical analysis of NiTi and modified NiTi samples was conducted by energy dispersive x-ray method. The electrochemical behavior of NiTi alloy was evaluated using the potentiodynamic polarization scan and electrochemical impedance spectroscopy tests in Ringer solution after and prior to the shot pining process. The result of XRD analysis of modified samples showed an average crystalline size of 23 nm. Moreover, FE-SEM confirmed the development of a nanostructured alloy induced by shot pinning process. Modification of NiTi alloy by shot-peening process resulted in corrosion resistance improvement and decrease in the corrosion rate, which consequently led to less release rate of the toxic nickel ions in the corrosive environment, compared to the non-modified samples.

  4. Effect of micro-arc oxidation surface modification on the properties of the NiTi shape memory alloy.

    PubMed

    Xu, J L; Zhong, Z C; Yu, D Z; Liu, F; Luo, J M

    2012-12-01

    In this paper, the effects of micro-arc oxidation (MAO) surface modification (alumina coatings) on the phase transformation behavior, shape memory characteristics, in vitro haemocopatibility and cytocompatibility of the biomedical NiTi alloy were investigated respectively by differential scanning calorimetry, bending test, hemolysis ratio test, dynamic blood clotting test, platelet adhesion test and cytotoxicity testing by human osteoblasts (Hobs). The results showed that there were no obvious changes of the phase transformation temperatures and shape memory characteristics of the NiTi alloy after the MAO surface modification and the coating could withstand the thermal shock and volume change caused by martensite-austenite phase transformation. Compared to the uncoated NiTi alloys, the MAO surface modification could effectively improve the haemocopatibility of the coated NiTi alloys by the reduced hemolysis ratio, the prolonged dynamic clotting time and the decreased number of platelet adhesion; and the rough and porous alumina coatings could obviously promote the adherence, spread and proliferation of the Hobs with the significant increase of proliferation number of Hobs adhered on the surface of the coated NiTi alloys (P < 0.05).

  5. The Effect of Thermal Annealing on Structural-phase Changes in the Ni-Ti Alloy Implanted with Krypton Ions

    NASA Astrophysics Data System (ADS)

    Poltavtseva, V. P.; Kislitsin, S. B.; Ghyngazov, S. A.

    2016-06-01

    The influence of thermal annealing within the temperature range 100-300°C on the structural-phase state of a Ni-Ti alloy with shape memory effect (SME) implanted with 84Kr ions at the energies E = 280 keV and 1.75 MeV/nucl and the fluences within 5·1012-1·1020 ion/m2 is investigated. For the samples modified by 84Kr ions at E = 1.75 MeV/nucl up to the fluences 1·1020 and 5·1012 ion/m2, the formation of a martensitic NiTi phase with the B19 ' structure, responsible for the SME, is revealed at the annealing temperatures 100 and 300°C, respectively, in the near-surface region corresponding to the outrange area. This is accompanied by the formation of nanosized NiTi particles in the R-phase. As the implantation fluence increases, the probability of their formation decreases. It is shown that annealing of the implanted structures can increase the strength of the Ni-Ti alloy. The degree of hardening is determined by the value of annealing temperature, and an increase in strength is primarily due to ordering of the radiation-induced defect structures (phases). A correlation between the onset temperature of a forward martensitic transition and the structural-phase state of the thermally annealed Ni-Ti alloy is established.

  6. An In Situ Study of Sintering Behavior and Phase Transformation Kinetics in NiTi Using Neutron Diffraction

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Liss, Klaus-Dieter; Cao, Peng

    2015-12-01

    The powder sintering behavior of NiTi from an elemental powder mixture of Ni/Ti has been investigated, using an in situ neutron diffraction technique. In the sintered alloys, the overall porosity ranges from 9.2 to 15.6 pct, while the open-to-overall porosity ratio is between 8.3 and 63.7 pct and largely depends on the sintering temperature. In comparison to powder compacts sintered at 1223 K and 1373 K (950 °C and 1100 °C), the powder compact sintered at 1153 K (880 °C) shows a much smaller pore size, a higher open-to-overall porosity ratio but smaller shrinkage and a lower density. Direct evidence of eutectoid transformation in the binary Ni-Ti system during furnace cooling to ca. 890 K (617 °C) is provided by in situ neutron diffraction. The intensities of the B2-NiTi reflections decrease during the holding stage at 1373 K (1100 °C), which has been elaborated as an extinction effect according to the dynamical theory of neutron diffraction, when distorted crystallites gradually recover to perfect crystals. The analysis on the first five reflections clarifies the non-existence of any order-disorder transition in the NiTi phase from B2-to-BCC structure.

  7. A combination of organic carbon/total nitrogen ratios and pyrite contents in sediments as a paleoenvironmental indicator: A preliminary study in northern Kyushu, Japan

    SciTech Connect

    Miki, Takashi; Aizawa, Jun

    1995-01-01

    Organic carbon (Corg) and total nitrogen (N) contents in Tertiary mudstone samples from four basins in northern Kyushu, Japan, were determined by using a CHN analyzer. A good correlation was observed between the stratigraphic distribution of the Corg/N values and geologically inferred depositional environments. Pyrite contents in carbonaceous sediments from the same basins were also obtained employing a reflecting microscope. Stratigraphic changes of pyrite content in carbonaceous sediments can be correlated with these depositional environments. Pyrite is expected to play a useful role as an index mineral in estimation of depositional environments in future studies.

  8. Soil organic carbon as a factor in passive microwave retrievals of soil water content over agricultural croplands

    NASA Astrophysics Data System (ADS)

    Manns, Hida R.; Berg, Aaron A.; Colliander, Andreas

    2015-09-01

    Remote sensing has the potential to deliver global soil water content (SWC) on vast scales with frequent revisit times for progress in the fields of climate, weather forecasting, agriculture and hydrology. Although surface roughness, vegetation and soil texture have been established as sources of variability in passive microwave interpretation, soil organic carbon (SOC) has not typically been considered as a factor that affects SWC estimation during field sampling campaigns. SOC was observed along with soil texture and bulk density during the Soil Moisture Active Passive Validation Experiment in 2012 (SMAPVEX12), the Soil Moisture Active Passive (SMAP) satellite algorithm development field sampling campaign held June 6 to July 19 in Southern Manitoba, Canada. Aerial measurements from the PALS (Passive Active L-band System) instrument were recorded over agricultural fields and forest areas from aircraft while SWC was measured simultaneously on the ground with resistance probes on 17 sampling dates. Additionally, fields were sampled for surface roughness, vegetation growth and water content, soil and vegetation temperature and soil physical characteristics. A soil core was collected on each field each sampling time to assess bulk density, soil particle size and SOC. SOC accounted for more variability in the anomalies between PALS and ground sampled SWC than sand, clay or bulk density, although all soil variables explained significant variability. With analysis by partial least squares multiple regression over 11 sampling dates and 39 fields where both ground and PALS data were well represented, only SOC contributed significantly to the regression of SWC beyond the variance all soil variables had in common. The significance of SOC in the relative SWC anomalies was highest in very wet and very dry conditions and in loam soil over all sampling dates, while bulk density was more significant in sand soils. This analysis suggests SOC is a simple variable that incorporates

  9. Storm Event Variability in Particulate Organic Matter Source, Size, and Carbon and Nitrogen Content Along a Forested Drainage Network

    NASA Astrophysics Data System (ADS)

    Rowland, R. D.; Inamdar, S. P.; Parr, T. B.

    2015-12-01

    Coupled inputs of carbon and nitrogen comprise an important energy and nutrient subsidy for aquatic ecosystems. Large storm events can mobilize substantial amounts of these elements, especially in particulate form. While the role of storms in mobilizing allochthonous particulate organic matter (POM) is well recognized, less is known about the changes in source, particle size, and composition of POM as it is routed through the fluvial network. Questions we addressed include- (a) How does source, size, and C and N content of suspended POM vary with storm magnitude and intensity? (b) How does POM size and C and N content evolve along the drainage network? (c) How accurate are high-frequency, in-situ sensors in characterizing POM? We conducted this study in a 79 ha, forested catchment in the Piedmont region of Maryland. Event sampling for suspended POM was performed using automated stream water samplers and in-situ, high-frequency sensors (s::can specto::lyser and YSI EXO 2; 30 minute intervals) at 12 and 79 ha drainage locations. Composite storm-event sediment samples were also collected using passive samplers at five catchment drainage scales. Data is available for multiple storms since August 2014. Samples were partitioned into three discrete particle size classes (coarse: 1000-2000 µm, medium: 250-1000 µm, fine: < 250 µm) for organic C and N determination. Suspended sediments and seven soil end members were also analyzed for stable 13C and 15N isotopes ratios to characterize the evolution in sediment sources through the drainage network. Contrary to our expectations, preliminary results suggest finer suspended sediments in the upstream portion of the catchment, and that these may contain more POM. Unsurprisingly, sensors' ability to estimate the coarser particle classes via turbidity are weak compared to the finer class, but this is less pronounced in organic-rich sediments. Distinct patterns in in-situ absorbance spectra may suggest an ability to discern

  10. A sub-boiling distillation method for the preparation of low carbon content water from urine samples for tritium measurement by liquid scintillation counting.

    PubMed

    Nogawa, N; Makide, Y

    1999-06-01

    A new preparation method was developed for obtaining low carbon content water from urine samples for the measurement of tritium by a liquid scintillation counter. The method uses a simple and convenient subboiling distillation bottle. Many urine samples have been purified by this method and the change of tritium level in a tritium-handling radiation-worker was observed.

  11. Fabrication of Metal Nanoparticle-Modified Screen Printed Carbon Electrodes for the Evaluation of Hydrogen Peroxide Content in Teeth Whitening Strips

    ERIC Educational Resources Information Center

    Popa, Adriana; Abenojar, Eric C.; Vianna, Adam; Buenviaje, Czarina Y. A.; Yang, Jiahua; Pascual, Cherrie B.; Samia, Anna Cristina S.

    2015-01-01

    A laboratory experiment in which students synthesize Ag, Au, and Pt nanoparticles (NPs) and use them to modify screen printed carbon electrodes for the electroanalysis of the hydrogen peroxide content in commercially available teeth whitening strips is described. This experiment is designed for two 3-h laboratory periods and can be adapted for…

  12. Determination of ascorbic acid content of some fruit juices and wine by voltammetry performed at pt and carbon paste electrodes.

    PubMed

    Pisoschi, Aurelia Magdalena; Pop, Aneta; Negulescu, Gheorghe Petre; Pisoschi, Aurel

    2011-02-01

    A method was developed for assessing ascorbic acid concentration in fruit juices and wine by differential pulse voltammetry. The oxidation peak for ascorbic acid occurs at about 530 mV (versus SCE) on a Pt strip working electrode and at about 470 mV on a carbon paste working electrode. The influence of the operational parameters like the pulse amplitude and the pulse period on the analytical signal was investigated. The obtained calibration graph shows a linear dependence between the peak height and ascorbic acid concentration within the range 0.31-20 mM with a Pt working electrode, and within the range 0.07-20 mM with a carbon paste working electrode. The equation of the calibration graph was y = 21.839x + 35.726, r² = 0.9940, when a Pt strip electrode was used (where y represents the value of the current intensity measured for the peak height, expressed as µA and x the analyte concentration, as mM). R.S.D. = 2.09%, n = 10, C(ascorbic acid) = 2.5 mM. The equation of the calibration graph was y = 3.4429x + 5.7334, r² = 0.9971, when a carbon paste electrode was used (where y represents the value of intensity measured for the peak height, expressed as µA and x the analyte concentration, as mM). R.S.D. = 2.35%, n = 10, C(ascorbic acid) = 2.5 mM. The developed method was applied to ascorbic acid assessment in fruit juices and wine. The ascorbic acid content determined ranged between 6.83 mg/100 mL juice for soft drinks (Fanta Madness) and 54.74 mg/100 mL for citrus (lemon) juices obtained by squeezing fruit. Different ascorbic acid concentrations (from standard solutions) were added to the analysed samples, the degree of recovery being comprised between 94.74 and 104.97%. The results of ascorbic acid assessment by differential pulse voltammetry were compared with those obtained by cyclic voltammetry. The results obtained by the two methods were in good agreement.

  13. A rational synthesis of hierarchically porous, N-doped carbon from Mg-based MOFs: understanding the link between nitrogen content and oxygen reduction electrocatalysis.

    PubMed

    Eisenberg, David; Stroek, Wowa; Geels, Norbert J; Tanase, Stefania; Ferbinteanu, Marilena; Teat, Simon J; Mettraux, Pierre; Yan, Ning; Rothenberg, Gadi

    2016-07-27

    Controlled mixtures of novel Mg-based metal-organic frameworks (MOFs) were prepared, with H(+) or K(+) as counterions. A linear relation was found between synthesis pH and K/H ratio in the resultant mixture, establishing the tunability of the synthesis. Upon pyrolysis, these precursor mixtures yield nitrogen-doped, hierarchically porous carbons, which have good activity towards the oxygen reduction reaction (ORR) at pH 13. The nitrogen content varies significantly along the homologous carbon series (>400%, 1.3 at% to 5.7 at%), to a much greater extent than microstructural parameters such as surface area and graphitization. This allows us to isolate the positive correlation between nitrogen content and electrocatalytic oxygen reduction ORR activity in this class of metal-free, N-doped, porous carbons. PMID:27412725

  14. Comparison of Gas Sensors Based on Oxygen Plasma-Treated Carbon Nanotube Network Films with Different Semiconducting Contents

    NASA Astrophysics Data System (ADS)

    Ham, Seung Woo; Hong, Hyun Pyo; Kim, Jin Woong; Kim, Jong Hyun; Kim, Ki Bum; Park, Chan Won; Min, Nam Ki

    2015-05-01

    We report on the effect of oxygen plasma treatment on the performance of single-wall carbon nanotube (SWCNT) NH3 gas sensors with different semiconducting contents (66% and 90% semiconducting SWCNTs). The performance of chemical sensors based on SWCNT networks depends on the concentration of semiconducting SWCNTs (s-SWCNTs), whose conductance can be significantly modulated by the absorbed molecules and the surface functionalization. After oxygen plasma treatment, the 66% s-SWCNT sample showed an increase in sensitivity from 0.0275%/ppm to 0.1525%/ppm (5.5 times), while the 90% s-SWCNT device demonstrated an increase in sensitivity from 0.1184%/ppm to 1.5707%/ppm (13 times). These results correspond to improvements in sensitivity of 57 times and 10 times compared with pristine and plasma-treated 66% s-SWCNT samples, respectively. In addition, the plasma-treated sensors exhibited much faster response and recovery times than the pristine one. The large improvement in performance was explained by the presence of oxygen-containing functional groups and the sp2-sp3 structure change of SWCNTs, which changes the binding energy while increasing the uptake of polar molecules such as NH3.

  15. [Transformation characteristics of carbon, nitrogen, phosphorus and sulfur during thermal hydrolysis pretreatment of sludge with high solid content].

    PubMed

    Zhuo, Yang; Han, Yun; Cheng, Yao; Peng, Dang-Cong; Li, Yu-You

    2015-03-01

    The transformation characteristics of carbon, nitrogen, phosphorus and sulfur in dewatering sludge from municipal wastewater treatment plant (WWTP) were investigated after thermal hydrolysis pretreatment at 165 degress C for 50 min. The results showed that the hydrolysis efficiency of VSS could reach as high as 43.35%, 54.36% of protein and 65.12% of carbohydrate were transferred to dissolved organics, respectively, and the main component of dissolved organic matter in hydrolysate was dissolved protein (52.18% ), 54.23% of insoluble organic nitrogen was turned into dissolved nitrogen and 22.13% of dissolved nitrogen in hydrolysate was converted to ammonia. The transformation rate of insoluble phosphorus was 30.52%. Dissolved phosphorus was mostly transformed to phosphate (79.84%) as phosphorus-accumulating bacteria cells were crushed. 50.03% of insoluble organic sulfur was hydrolyzed, and little change was detected in sulfide (0.50%). The analysis results of the organic compounds transformation are valuable for treatment of the thermal hydrolysis pretreated sludge with high solid content.

  16. Shape-memory transformations of NiTi: Minimum-energy pathways between austenite, martensites, and kinetically limited intermediate states

    DOE PAGES

    Zarkevich, N. A.; Johnson, D. D.

    2014-12-24

    NiTi is the most used shape-memory alloy, nonetheless, a lack of understanding remains regarding the associated structures and transitions, including their barriers. Using a generalized solid-state nudge elastic band (GSSNEB) method implemented via density-functional theory, we detail the structural transformations in NiTi relevant to shape memory: those between body-centered orthorhombic (BCO) groundstate and a newly identified stable austenite (“glassy” B2-like) structure, including energy barriers (hysteresis) and intermediate structures (observed as a kinetically limited R-phase), and between martensite variants (BCO orientations). All results are in good agreement with available experiment. We contrast the austenite results to those from the often-assumed, butmore » unstable B2. Furthermore, these high- and low-temperature structures and structural transformations provide much needed atomic-scale detail for transitions responsible for NiTi shape-memory effects.« less

  17. Shape-memory transformations of NiTi: Minimum-energy pathways between austenite, martensites, and kinetically limited intermediate states

    SciTech Connect

    Zarkevich, N. A.; Johnson, D. D.

    2014-12-24

    NiTi is the most used shape-memory alloy, nonetheless, a lack of understanding remains regarding the associated structures and transitions, including their barriers. Using a generalized solid-state nudge elastic band (GSSNEB) method implemented via density-functional theory, we detail the structural transformations in NiTi relevant to shape memory: those between body-centered orthorhombic (BCO) groundstate and a newly identified stable austenite (“glassy” B2-like) structure, including energy barriers (hysteresis) and intermediate structures (observed as a kinetically limited R-phase), and between martensite variants (BCO orientations). All results are in good agreement with available experiment. We contrast the austenite results to those from the often-assumed, but unstable B2. Furthermore, these high- and low-temperature structures and structural transformations provide much needed atomic-scale detail for transitions responsible for NiTi shape-memory effects.

  18. Shape-Memory Transformations of NiTi: Minimum-Energy Pathways between Austenite, Martensites, and Kinetically Limited Intermediate States

    NASA Astrophysics Data System (ADS)

    Zarkevich, N. A.; Johnson, D. D.

    2014-12-01

    NiTi is the most used shape-memory alloy; nonetheless, a lack of understanding remains regarding the associated structures and transitions, including their barriers. Using a generalized solid-state nudged elastic band method implemented via density-functional theory, we detail the structural transformations in NiTi relevant to shape memory: those between a body-centered orthorhombic (bco) ground state and a newly identified stable austenite ("glassy" B 2 -like) structure, including energy barriers (hysteresis) and intermediate structures (observed as a kinetically limited R phase), and between martensite variants (bco orientations). All results are in good agreement with available experiment. We contrast the austenite results to those from the often-assumed, but unstable B 2 . These high- and low-temperature structures and structural transformations provide much needed atomic-scale detail for transitions responsible for NiTi shape-memory effects.

  19. Structural phase states in NiTi near-surface layers modified by electron and ion beams

    SciTech Connect

    Meisner, Ludmila Meisner, Stanislav; Mironov, Yurii Kashin, Oleg Lotkov, Aleksandr; Kudryashov, Andrey

    2014-11-14

    The paper considers the effects arising on X-ray diffraction patterns taken in different diffraction geometries and how these effects can be interpreted to judge structural states in NiTi near-surface regions after electron and ion beam treatment. It is shown that qualitative and quantitative analysis of phase composition, lattice parameters of main phases, elastic stress states, and their in-depth variation requires X-ray diffraction patterns in both symmetric Bragg–Brentano and asymmetric Lambot–Vassamilleta geometries with variation in X-ray wavelengths and imaging conditions (with and with no β-filter). These techniques of structural phase analysis are more efficient when the thickness of modified NiTi surface layers is 1–10 μm (after electron beam treatment) and requires special imaging conditions when the thickness of modified NiTi surface layers is no greater than 1 μm (after ion beam treatment)

  20. Combined effects of different heat treatments and Cu element on transformation behavior of NiTi orthodontic wires.

    PubMed

    Seyyed Aghamiri, S M; Ahmadabadi, M Nili; Raygan, Sh

    2011-04-01

    The shape memory nickel-titanium alloy has been applied in many fields due to its unique thermal and mechanical performance. One of the successful applications of NiTi wires is in orthodontics because of its good characteristics such as low stiffness, high spring back, high stored energy, biocompatibility, superelasticity and shape memory effect. The mechanical properties of wires are paid special attention which results in achieving continuous optimal forces and eventually causing rapid tooth movement without any damage. The behavior of the alloy can be controlled by chemical composition and thermo-mechanical treatment during the manufacturing process. In this study two kinds of commercial superelastic NiTi archwires of 0.41 mm diameter were investigated: Copper NiTi and Highland Metal. The chemical analysis of both wires was estimated by energy dispersive spectroscopy (EDS). It was showed that Copper NiTi wire contained copper and chromium. The two types of wires were exposed to different heat treatment conditions at 400 and 500 °C for 10 and 60 min to compare the behavior of the wires at aged and as-received conditions. Phase transformation temperatures clarified by differential scanning calorimetry (DSC) showed B2 <--> R <--> B19 transformation in Highland Metal wire and B2 <--> B19(') transformation in Copper NiTi wire. Three point bending (TPB) tests in the certain designed fixture were performed at 37 °C to evaluate the mechanical behavior of the wires. The experimental results revealed the superelastic behavior of the Highland Metal wire after 60 min ageing at 400 and 500 °C and the plastic deformation of the Copper NiTi wire after annealing due to the effect of copper in the alloy composition. PMID:21316617

  1. Hydrogen release from titanium hydride in foaming of orthopedic NiTi scaffolds.

    PubMed

    Wu, Shuilin; Liu, Xiangmei; Yeung, K W K; Hu, Tao; Xu, Zushun; Chung, Jonathan C Y; Chu, Paul K

    2011-03-01

    Titanium hydride powders are utilized to enhance the foaming process in the formation of orthopedic NiTi scaffolds during capsule-free hot isostatic pressing. In order to study the formation mechanism, the thermal behavior of titanium hydride and hydrogen release during the heating process are systematically investigated in air and argon and under vacuum by X-ray diffraction (XRD), thermal analysis, including thermogravimetric analysis and differential scanning calorimetry, energy dispersive X-ray spectroscopy, and transmission electron microscopy. Our experiments reveal that hydrogen is continuously released from titanium hydride as the temperature is gradually increased from 300 to 700 °C. Hydrogen is released in two transitions: TiH1.924→TiH1.5/TiH1.7 between 300 °C and 400 °C and TiH1.5/TiH1.7→α-Ti between 400 °C and 600 °C. In the lower temperature range between 300 °C and 550 °C the rate of hydrogen release is slow, but the decomposition rate increases sharply above 550 °C. The XRD patterns obtained in air and under vacuum indicate that the surface oxide layer can deter hydrogen release. The pressure change is monitored in real time and the amount of hydrogen released is affected by the processing temperature and holding time. Holding processes at 425 °C, 480 °C, 500 °C, 550 °C, and 600 °C are found to significantly improve the porous structure in the NiTi scaffolds due to the stepwise release of hydrogen. NiTi scaffolds foamed by stepwise release of hydrogen are conducive to the attachment and proliferation of osteoblasts and the resulting pore size also favor in-growth of cells. PMID:20965283

  2. Characterization of NiTi Shape Memory Damping Elements designed for Automotive Safety Systems

    NASA Astrophysics Data System (ADS)

    Strittmatter, Joachim; Clipa, Victor; Gheorghita, Viorel; Gümpel, Paul

    2014-07-01

    Actuator elements made of NiTi shape memory material are more and more known in industry because of their unique properties. Due to the martensitic phase change, they can revert to their original shape by heating when subjected to an appropriate treatment. This thermal shape memory effect (SME) can show a significant shape change combined with a considerable force. Therefore such elements can be used to solve many technical tasks in the field of actuating elements and mechatronics and will play an increasing role in the next years, especially within the automotive technology, energy management, power, and mechanical engineering as well as medical technology. Beside this thermal SME, these materials also show a mechanical SME, characterized by a superelastic plateau with reversible elongations in the range of 8%. This behavior is based on the building of stress-induced martensite of loaded austenite material at constant temperature and facilitates a lot of applications especially in the medical field. Both SMEs are attended by energy dissipation during the martensitic phase change. This paper describes the first results obtained on different actuator and superelastic NiTi wires concerning their use as damping elements in automotive safety systems. In a first step, the damping behavior of small NiTi wires up to 0.5 mm diameter was examined at testing speeds varying between 0.1 and 50 mm/s upon an adapted tensile testing machine. In order to realize higher testing speeds, a drop impact testing machine was designed, which allows testing speeds up to 4000 mm/s. After introducing this new type of testing machine, the first results of vertical-shock tests of superelastic and electrically activated actuator wires are presented. The characterization of these high dynamic phase change parameters represents the basis for new applications for shape memory damping elements, especially in automotive safety systems.

  3. Texture memory and strain-texture mapping in a NiTi shape memory alloy

    SciTech Connect

    Ye, B.; Majumdar, B. S.; Dutta, I.

    2007-08-06

    The authors report on the near-reversible strain hysteresis during thermal cycling of a polycrystalline NiTi shape memory alloy at a constant stress that is below the yield strength of the martensite. In situ neutron diffraction experiments are used to demonstrate that the strain hysteresis occurs due to a texture memory effect, where the martensite develops a texture when it is cooled under load from the austenite phase and is thereafter ''remembered.'' Further, the authors quantitatively relate the texture to the strain by developing a calculated strain-texture map or pole figure for the martensite phase, and indicate its applicability in other martensitic transformations.

  4. Design of a suture anchor based on the superelasticity of the Ni-Ti alloy.

    PubMed

    Puértolas, J A; Pérez-García, J M; Juan, E; Ríos, R

    2002-01-01

    We have designed and manufacture a prototype of a new anchoring system for soft bone tissue fixation, based on the superelasticity of the Ni-Ti alloy. The anchoring capability has been observed in femoral hips by radiographs. The performance of this new anchor have been measured by tensile experiments and contrasted with finite element model. The results point out that keeping the fixation capacity, the new configuration presents advantages concerning to a minor damaged volume bone, a reduction of the manufacture cost and a simpler insertion. PMID:12446943

  5. Shape-memory properties in Ni-Ti sputter-deposited film

    NASA Technical Reports Server (NTRS)

    Busch, J. D.; Johnson, A. D.; Lee, C. H.; Stevenson, D. A.

    1990-01-01

    A Ni-Ti alloy, generically called nitinol, was prepared from sputtering targets of two different compositions on glass substrates using a dc magnetron source. The as-deposited films were amorphous in structure and did not exhibit a shape memory. The amorphous films were crystallized with a suitable annealing process, and the transformation properties were measured using differential scanning calorimetry. The annealed films demonstrated a strong shape-memory effect. Stress/strain measurements and physical manipulation were used to evaluate the shape recovery. These tests demonstrated sustained tensile stresses of up to 480 MPa in the high-temperature phase, and a characteristic plastic deformation in the low-temperature phase.

  6. Surface structure and properties of biomedical NiTi shape memory alloy after Fenton's oxidation.

    PubMed

    Chu, C L; Hu, T; Wu, S L; Dong, Y S; Yin, L H; Pu, Y P; Lin, P H; Chung, C Y; Yeung, K W K; Chu, Paul K

    2007-09-01

    Fenton's oxidation is traditionally used to remove inorganic and organic pollutants from water in waster water treatment. It is an advanced oxidation process in which H2O2 is catalytically decomposed by ferrous irons into hydroxyl radicals (*OH) which have a higher oxidation potential (2.8V) than H2O2. In the work reported here, we for the first time use Fenton's oxidation to modify the surface of biomedical NiTi shape memory alloy (SMA). The influences of Fenton's oxidation on the surface microstructure, blood compatibility, leaching of harmful Ni ions and corrosion resistance in simulated body fluids is assessed using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma mass spectrometry, electrochemical tests, hemolysis analysis and the blood platelet adhesion test. The mechanical stability of the surface titania film produced by Fenton's oxidation as well as their effects on the shape memory behavior of the SMA are studied by bending tests. Our results show that Fenton's oxidation produces a novel nanostructured titania gel film with a graded structure on the NiTi substrate without an intermediate Ni-rich layer that is typical of high-temperature oxidation. Moreover, there is a clear Ni-free zone near the top surface of the titania film. The surface structural changes introduced by Fenton's oxidation improve the electrochemical corrosion resistance and mitigate Ni release. The latter effects are comparable to those observed after oxygen plasma immersion ion implantation reported previously and better than those of high-temperature oxidation. Aging in boiling water improves the crystallinity of the titania film and further reduces Ni leaching. Blood platelet adhesion is remarkably reduced after Fenton's oxidation, suggesting that the treated SMA has improved thrombo resistance. Enhancement of blood compatibility is believed to stem from the improved hemolysis resistance, the surface wettability and the

  7. Substrate temperature effects on laser crystallized NiTi thin films

    SciTech Connect

    Birnbaum, A. J.; Yao, Y. L.; Chung, Ui-Jin; Im, James S.; Huang, X.; Ramirez, A. G.

    2009-04-01

    Amorphous sputter-deposited NiTi thin films were subjected to pulsed, melt-mediated laser crystallization techniques to engineer their microstructure. The effects of laser processing of preheated films are examined. Laser processing of films at an elevated substrate temperature has a significant effect on the rate with which solidification occurs. It is observed that the preheating temperature at which processing is carried out has significant implications for the resulting phase and microstructure, and therefore mechanical properties. Furthermore, the microstructural effects of varying incident laser energy density are examined via atomic force microscopy, scanning electron microscopy, and x-ray diffraction, and mechanical/shape memory properties are characterized via nanoindentation.

  8. Functionally grading the shape memory response in NiTi films: Laser irradiation

    SciTech Connect

    Birnbaum, A. J.; Satoh, G.; Yao, Y. L.

    2009-08-15

    A new process and mechanism are presented for controlling the shape memory response spatially within monolithic NiTi thin film structures. This technique is shown to effectively control the martensitic phase transformation temperature and exhibits control over aspects of the mechanical and shape memory responses as well. Specifically, the martensitic phase transformation temperature decreases with incident laser energy density. Concomitant modifications are observed in both the mechanical and shape memory responses in laser processed films. Analysis and characterization are performed via temperature controlled optical microscopy, x-ray diffraction, atomic force microscopy, and nanoindentation.

  9. Zinc oxide nanorod assisted rapid single-step process for the conversion of electrospun poly(acrylonitrile) nanofibers to carbon nanofibers with a high graphitic content

    NASA Astrophysics Data System (ADS)

    Nain, Ratyakshi; Singh, Dhirendra; Jassal, Manjeet; Agrawal, Ashwini K.

    2016-02-01

    The effect of incorporation of rigid zinc oxide (ZnO) nanostructures on carbonization behavior of electrospun special acrylic fiber grade poly(acrylonitrile) (PAN-SAF) nanofibers was investigated. ZnO nanorods with high aspect ratios were incorporated into a PAN-N,N-dimethylformamide system and the composite nanofibers reinforced with aligned ZnO rods up to 50 wt% were successfully electrospun, and subsequently, carbonized. The morphology and the structural analysis of the resultant carbon nanofibers revealed that the rigid ZnO nanorods, present inside the nanofibers, possibly acted as scaffolds (temporary support structures) for immobilization of polymer chains and assisted in uniform heat distribution. This facilitated rapid and efficient conversion of the polymer structure to the ladder, and subsequently, the graphitized structure. At the end of the process, the ZnO nanorods were found to completely separate from the carbonized fibers yielding pure carbon nanofibers with a high graphitic content and surface area. The approach could be used to eliminate the slow, energy intensive stabilization step and achieve fast conversion of randomly laid carbon nanofiber webs in a single step to carbon nanofibers without the application of external tension or internal templates usually employed to achieve a high graphitic content in such systems.The effect of incorporation of rigid zinc oxide (ZnO) nanostructures on carbonization behavior of electrospun special acrylic fiber grade poly(acrylonitrile) (PAN-SAF) nanofibers was investigated. ZnO nanorods with high aspect ratios were incorporated into a PAN-N,N-dimethylformamide system and the composite nanofibers reinforced with aligned ZnO rods up to 50 wt% were successfully electrospun, and subsequently, carbonized. The morphology and the structural analysis of the resultant carbon nanofibers revealed that the rigid ZnO nanorods, present inside the nanofibers, possibly acted as scaffolds (temporary support structures) for

  10. Pseudomonas aeruginosa RRALC3 Enhances the Biomass, Nutrient and Carbon Contents of Pongamia pinnata Seedlings in Degraded Forest Soil.

    PubMed

    Radhapriya, Parthasarathy; Ramachandran, Andimuthu; Anandham, Rangasamy; Mahalingam, Sundararajan

    2015-01-01

    The study was aimed at assessing the effects of indigenous Plant Growth Promoting Bacterium (PGPB) on the legume Pongamia pinnata in the degraded soil of the Nanmangalam Reserve Forest (NRF) under nursery conditions. In total, 160 diazotrophs were isolated from three different nitrogen-free semi-solid media (LGI, Nfb, and JMV). Amongst these isolates, Pseudomonas aeruginosa RRALC3 exhibited the maximum ammonia production and hence was selected for further studies. RRALC3 was found to possess multiple plant growth promoting traits such as nitrogen accumulation (120.6ppm); it yielded a positive amplicon with nifH specific primers, tested positive for Indole Acetic Acid (IAA; 18.3μg/ml) and siderophore production, tested negative for HCN production and was observed to promote solubilization of phosphate, silicate and zinc in the plate assay. The 16S rDNA sequence of RRALC3 exhibited 99% sequence similarity to Pseudomonas aeruginosa JCM5962. Absence of virulence genes and non-hemolytic activity indicated that RRALC3 is unlikely to be a human pathogen. When the effects of RRALC3 on promotion of plant growth was tested in Pongamia pinnata, it was observed that in Pongamia seedlings treated with a combination of RRALC3 and chemical fertilizer, the dry matter increased by 30.75%. Nitrogen, phosphorus and potassium uptake increased by 34.1%, 27.08%, and 31.84%, respectively, when compared to control. Significant enhancement of total sugar, amino acids and organic acids content, by 23.4%, 29.39%, and 26.53% respectively, was seen in the root exudates of P. pinnata. The carbon content appreciated by 4-fold, when fertilized seedlings were treated with RRALC3. From the logistic equation, the rapid C accumulation time of Pongamia was computed as 43 days longer than the control when a combination of native PGPB and inorganic fertilizer was applied. The rapid accumulation time of N, P and K in Pongamia when treated with the same combination as above was 15, 40 and 33 days longer

  11. Pseudomonas aeruginosa RRALC3 Enhances the Biomass, Nutrient and Carbon Contents of Pongamia pinnata Seedlings in Degraded Forest Soil

    PubMed Central

    Radhapriya, Parthasarathy; Ramachandran, Andimuthu; Anandham, Rangasamy; Mahalingam, Sundararajan

    2015-01-01

    The study was aimed at assessing the effects of indigenous Plant Growth Promoting Bacterium (PGPB) on the legume Pongamia pinnata in the degraded soil of the Nanmangalam Reserve Forest (NRF) under nursery conditions. In total, 160 diazotrophs were isolated from three different nitrogen-free semi-solid media (LGI, Nfb, and JMV). Amongst these isolates, Pseudomonas aeruginosa RRALC3 exhibited the maximum ammonia production and hence was selected for further studies. RRALC3 was found to possess multiple plant growth promoting traits such as nitrogen accumulation (120.6ppm); it yielded a positive amplicon with nifH specific primers, tested positive for Indole Acetic Acid (IAA; 18.3μg/ml) and siderophore production, tested negative for HCN production and was observed to promote solubilization of phosphate, silicate and zinc in the plate assay. The 16S rDNA sequence of RRALC3 exhibited 99% sequence similarity to Pseudomonas aeruginosa JCM5962. Absence of virulence genes and non-hemolytic activity indicated that RRALC3 is unlikely to be a human pathogen. When the effects of RRALC3 on promotion of plant growth was tested in Pongamia pinnata, it was observed that in Pongamia seedlings treated with a combination of RRALC3 and chemical fertilizer, the dry matter increased by 30.75%. Nitrogen, phosphorus and potassium uptake increased by 34.1%, 27.08%, and 31.84%, respectively, when compared to control. Significant enhancement of total sugar, amino acids and organic acids content, by 23.4%, 29.39%, and 26.53% respectively, was seen in the root exudates of P. pinnata. The carbon content appreciated by 4-fold, when fertilized seedlings were treated with RRALC3. From the logistic equation, the rapid C accumulation time of Pongamia was computed as 43 days longer than the control when a combination of native PGPB and inorganic fertilizer was applied. The rapid accumulation time of N, P and K in Pongamia when treated with the same combination as above was 15, 40 and 33 days longer

  12. Pseudomonas aeruginosa RRALC3 Enhances the Biomass, Nutrient and Carbon Contents of Pongamia pinnata Seedlings in Degraded Forest Soil.

    PubMed

    Radhapriya, Parthasarathy; Ramachandran, Andimuthu; Anandham, Rangasamy; Mahalingam, Sundararajan

    2015-01-01

    The study was aimed at assessing the effects of indigenous Plant Growth Promoting Bacterium (PGPB) on the legume Pongamia pinnata in the degraded soil of the Nanmangalam Reserve Forest (NRF) under nursery conditions. In total, 160 diazotrophs were isolated from three different nitrogen-free semi-solid media (LGI, Nfb, and JMV). Amongst these isolates, Pseudomonas aeruginosa RRALC3 exhibited the maximum ammonia production and hence was selected for further studies. RRALC3 was found to possess multiple plant growth promoting traits such as nitrogen accumulation (120.6ppm); it yielded a positive amplicon with nifH specific primers, tested positive for Indole Acetic Acid (IAA; 18.3μg/ml) and siderophore production, tested negative for HCN production and was observed to promote solubilization of phosphate, silicate and zinc in the plate assay. The 16S rDNA sequence of RRALC3 exhibited 99% sequence similarity to Pseudomonas aeruginosa JCM5962. Absence of virulence genes and non-hemolytic activity indicated that RRALC3 is unlikely to be a human pathogen. When the effects of RRALC3 on promotion of plant growth was tested in Pongamia pinnata, it was observed that in Pongamia seedlings treated with a combination of RRALC3 and chemical fertilizer, the dry matter increased by 30.75%. Nitrogen, phosphorus and potassium uptake increased by 34.1%, 27.08%, and 31.84%, respectively, when compared to control. Significant enhancement of total sugar, amino acids and organic acids content, by 23.4%, 29.39%, and 26.53% respectively, was seen in the root exudates of P. pinnata. The carbon content appreciated by 4-fold, when fertilized seedlings were treated with RRALC3. From the logistic equation, the rapid C accumulation time of Pongamia was computed as 43 days longer than the control when a combination of native PGPB and inorganic fertilizer was applied. The rapid accumulation time of N, P and K in Pongamia when treated with the same combination as above was 15, 40 and 33 days longer

  13. One-Step Synthesis of Microporous Carbon Monoliths Derived from Biomass with High Nitrogen Doping Content for Highly Selective CO2 Capture.

    PubMed

    Geng, Zhen; Xiao, Qiangfeng; Lv, Hong; Li, Bing; Wu, Haobin; Lu, Yunfeng; Zhang, Cunman

    2016-08-04

    The one-step synthesis method of nitrogen doped microporous carbon monoliths derived from biomass with high-efficiency is developed using a novel ammonia (NH3)-assisted activation process, where NH3 serves as both activating agent and nitrogen source. Both pore forming and nitrogen doping simultaneously proceed during the process, obviously superior to conventional chemical activation. The as-prepared nitrogen-doped active carbons exhibit rich micropores with high surface area and high nitrogen content. Synergetic effects of its high surface area, microporous structure and high nitrogen content, especially rich nitrogen-containing groups for effective CO2 capture (i.e., phenyl amine and pyridine-nitrogen) lead to superior CO2/N2 selectivity up to 82, which is the highest among known nanoporous carbons. In addition, the resulting nitrogen-doped active carbons can be easily regenerated under mild conditions. Considering the outstanding CO2 capture performance, low production cost, simple synthesis procedure and easy scalability, the resulting nitrogen-doped microporous carbon monoliths are promising candidates for selective capture of CO2 in industrial applications.

  14. One-Step Synthesis of Microporous Carbon Monoliths Derived from Biomass with High Nitrogen Doping Content for Highly Selective CO2 Capture

    NASA Astrophysics Data System (ADS)

    Geng, Zhen; Xiao, Qiangfeng; Lv, Hong; Li, Bing; Wu, Haobin; Lu, Yunfeng; Zhang, Cunman

    2016-08-01

    The one-step synthesis method of nitrogen doped microporous carbon monoliths derived from biomass with high-efficiency is developed using a novel ammonia (NH3)-assisted activation process, where NH3 serves as both activating agent and nitrogen source. Both pore forming and nitrogen doping simultaneously proceed during the process, obviously superior to conventional chemical activation. The as-prepared nitrogen-doped active carbons exhibit rich micropores with high surface area and high nitrogen content. Synergetic effects of its high surface area, microporous structure and high nitrogen content, especially rich nitrogen-containing groups for effective CO2 capture (i.e., phenyl amine and pyridine-nitrogen) lead to superior CO2/N2 selectivity up to 82, which is the highest among known nanoporous carbons. In addition, the resulting nitrogen-doped active carbons can be easily regenerated under mild conditions. Considering the outstanding CO2 capture performance, low production cost, simple synthesis procedure and easy scalability, the resulting nitrogen-doped microporous carbon monoliths are promising candidates for selective capture of CO2 in industrial applications.

  15. One-Step Synthesis of Microporous Carbon Monoliths Derived from Biomass with High Nitrogen Doping Content for Highly Selective CO2 Capture.

    PubMed

    Geng, Zhen; Xiao, Qiangfeng; Lv, Hong; Li, Bing; Wu, Haobin; Lu, Yunfeng; Zhang, Cunman

    2016-01-01

    The one-step synthesis method of nitrogen doped microporous carbon monoliths derived from biomass with high-efficiency is developed using a novel ammonia (NH3)-assisted activation process, where NH3 serves as both activating agent and nitrogen source. Both pore forming and nitrogen doping simultaneously proceed during the process, obviously superior to conventional chemical activation. The as-prepared nitrogen-doped active carbons exhibit rich micropores with high surface area and high nitrogen content. Synergetic effects of its high surface area, microporous structure and high nitrogen content, especially rich nitrogen-containing groups for effective CO2 capture (i.e., phenyl amine and pyridine-nitrogen) lead to superior CO2/N2 selectivity up to 82, which is the highest among known nanoporous carbons. In addition, the resulting nitrogen-doped active carbons can be easily regenerated under mild conditions. Considering the outstanding CO2 capture performance, low production cost, simple synthesis procedure and easy scalability, the resulting nitrogen-doped microporous carbon monoliths are promising candidates for selective capture of CO2 in industrial applications. PMID:27488268

  16. One-Step Synthesis of Microporous Carbon Monoliths Derived from Biomass with High Nitrogen Doping Content for Highly Selective CO2 Capture

    PubMed Central

    Geng, Zhen; Xiao, Qiangfeng; Lv, Hong; Li, Bing; Wu, Haobin; Lu, Yunfeng; Zhang, Cunman

    2016-01-01

    The one-step synthesis method of nitrogen doped microporous carbon monoliths derived from biomass with high-efficiency is developed using a novel ammonia (NH3)-assisted activation process, where NH3 serves as both activating agent and nitrogen source. Both pore forming and nitrogen doping simultaneously proceed during the process, obviously superior to conventional chemical activation. The as-prepared nitrogen-doped active carbons exhibit rich micropores with high surface area and high nitrogen content. Synergetic effects of its high surface area, microporous structure and high nitrogen content, especially rich nitrogen-containing groups for effective CO2 capture (i.e., phenyl amine and pyridine-nitrogen) lead to superior CO2/N2 selectivity up to 82, which is the highest among known nanoporous carbons. In addition, the resulting nitrogen-doped active carbons can be easily regenerated under mild conditions. Considering the outstanding CO2 capture performance, low production cost, simple synthesis procedure and easy scalability, the resulting nitrogen-doped microporous carbon monoliths are promising candidates for selective capture of CO2 in industrial applications. PMID:27488268

  17. The effect of aspect ratio and sp2/sp3 content on the field emission properties of carbon films grown by Ns-spiked PECVD

    SciTech Connect

    Tong, W.; Felter, T.E.; Pan, L.S.; Anders, S.; Cossy-Facre, A.; Stammler, T.

    1998-04-01

    The authors have deposited carbon films from mixtures of methane and N{sub 2} using Plasma Enhanced Chemical Vapor Deposition. By changing the percentage of N{sub 2} in the feed gas, they were able to produce films that have various aspect ratios and sp{sup 2}/sp{sup 3} contents. The film with the highest field emission contains spears of aspect ratio of 10:1. They also found that in their sp{sup 3}-rich films, higher sp{sup 2} content enhanced field emission. This is ascribed to improved charge transport to the field emission sites.

  18. Determination of the carbon, hydrogen and nitrogen contents of alanine and their uncertainties using the certified reference material L-alanine (NMIJ CRM 6011-a).

    PubMed

    Itoh, Nobuyasu; Sato, Ayako; Yamazaki, Taichi; Numata, Masahiko; Takatsu, Akiko

    2013-01-01

    The carbon, hydrogen, and nitrogen (CHN) contents of alanine and their uncertainties were estimated using a CHN analyzer and the certified reference material (CRM) L-alanine. The CHN contents and their uncertainties, as measured using the single-point calibration method, were 40.36 ± 0.20% for C, 7.86 ± 0.13% for H, and 15.66 ± 0.09% for N; the results obtained using the bracket calibration method were also comparable. The method described in this study is reasonable, convenient, and meets the general requirement of having uncertainties ≤ 0.4%.

  19. Interaction of hydration, aging, and carbon content of soil on the evaporation and skin bioavailability of munition contaminants.

    PubMed

    Reifenrath, William G; Kammen, Harold O; Reddy, Gunda; Major, Michael A; Leach, Glenn J

    2008-01-01

    Water plays a key role in enhancing the permeability of human skin to many substances. To further understand its ability to potentially increase the bioavailability of soil contaminants, artificial sweat was applied to excised pig skin prior to dosing with munition-contaminated soils. Skin was mounted in chambers to allow simultaneous measurement of evaporation and penetration and to control air flow, which changed the dwell time of skin surface water within a l-h period post application of test materials. Additional variables included type of compound, aging of spiked soil samples, and carbon content of soil. To this end, the evaporation and skin penetration of C-14 labeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,6-dinitrotoluene (26DNT), and 2,4,6-trinitrotoluene (TNT) were determined from two soil types, Yolo, having 1.2% carbon, and Tinker, having 9.5% carbon. RDX soil samples aged 27 mo and 62 mo were compared to freshly spiked soils samples. Similarly, 26DNT samples aged 35-36 mo and TNT samples aged 18 mo were compared to freshly spiked samples. Approximately 10 microg/cm(2) of radiolabeled compound was applied in 10 mg/cm(2) of soil. Radiolabel recovered from the dermis and tissue culture media (receptor fluid) was summed to determine percent absorption from the soils. Radiolabel recovered from vapor traps determined evaporation. Mean skin absorption of all compounds was higher for low-carbon soil, regardless of soil age and skin surface water as affected by air flow conditions. For 26DNT, a simultaneous increase in evaporation and penetration with conditions that favored enhanced soil hydration of freshly prepared samples was consistent with a mechanism that involved water displacement of 26DNT from its binding sites. A mean penetration of 17.5 +/- 3.6% was observed for 26DNT in low-carbon soil, which approached the value previously reported for acetone vehicle (24 +/- 6%). 26DNT penetration was reduced to 0.35% under dryer conditions and to 0

  20. Interaction of hydration, aging, and carbon content of soil on the evaporation and skin bioavailability of munition contaminants.

    PubMed

    Reifenrath, William G; Kammen, Harold O; Reddy, Gunda; Major, Michael A; Leach, Glenn J

    2008-01-01

    Water plays a key role in enhancing the permeability of human skin to many substances. To further understand its ability to potentially increase the bioavailability of soil contaminants, artificial sweat was applied to excised pig skin prior to dosing with munition-contaminated soils. Skin was mounted in chambers to allow simultaneous measurement of evaporation and penetration and to control air flow, which changed the dwell time of skin surface water within a l-h period post application of test materials. Additional variables included type of compound, aging of spiked soil samples, and carbon content of soil. To this end, the evaporation and skin penetration of C-14 labeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,6-dinitrotoluene (26DNT), and 2,4,6-trinitrotoluene (TNT) were determined from two soil types, Yolo, having 1.2% carbon, and Tinker, having 9.5% carbon. RDX soil samples aged 27 mo and 62 mo were compared to freshly spiked soils samples. Similarly, 26DNT samples aged 35-36 mo and TNT samples aged 18 mo were compared to freshly spiked samples. Approximately 10 microg/cm(2) of radiolabeled compound was applied in 10 mg/cm(2) of soil. Radiolabel recovered from the dermis and tissue culture media (receptor fluid) was summed to determine percent absorption from the soils. Radiolabel recovered from vapor traps determined evaporation. Mean skin absorption of all compounds was higher for low-carbon soil, regardless of soil age and skin surface water as affected by air flow conditions. For 26DNT, a simultaneous increase in evaporation and penetration with conditions that favored enhanced soil hydration of freshly prepared samples was consistent with a mechanism that involved water displacement of 26DNT from its binding sites. A mean penetration of 17.5 +/- 3.6% was observed for 26DNT in low-carbon soil, which approached the value previously reported for acetone vehicle (24 +/- 6%). 26DNT penetration was reduced to 0.35% under dryer conditions and to 0

  1. The influence of bracket type on the force delivery of Ni-Ti archwires.

    PubMed

    Hemingway, R; Williams, R L; Hunt, J A; Rudge, S J

    2001-06-01

    This study investigated the force delivery of an 0.014 inch nickel-titanium (Ni-Ti) archwire used in combination with a range of commercially available bracket systems, and using a model based on an 'ideal' mandibular archform. The model aimed to replicate the clinical interbracket span. The force delivery was measured at four different sites on an archwire for one batch of 10 nickel titanium archwires from one manufacturer, using one bracket/archwire combination. The four sites represented the lateral incisor, canine, second premolar and first molar positions. Force delivery was also measured for a further four different bracket designs at four different sites on the archwire using five fresh wires of the same archwire type. The wires were loaded with an M5 Nene Universal testing machine. The results demonstrate that the peak and plateau force, both of which are clinically important, are dependent on several factors of the archwire/bracket combination. The results showed that 20 per cent of the batch of 10 wires behaved differently by delivering a higher peak force. There was a statistically significant difference (P < 0.05) between the four bracket/archwire combinations for the peak forces delivered, but there was very little difference between the four bracket/archwire unloading force delivery values. The wires delivered a predictable force on the unloading curves, but self-ligating brackets may not develop sufficient strain within the wire to take full advantage of the superelastic effect of Ni-Ti wires. PMID:11471266

  2. Design, manufacture and evaluation of a NiTi stent for colon obstruction.

    PubMed

    Domingo, S; Puértolas, S; Gracia-Villa, L; Mainar, M; Usón, J; Puértolas, J A

    2005-01-01

    We have designed, manufactured and evaluated a prototype of a new stent based on the superelasticity of the NiTi alloy for colon obstruction, which is the first clinical manifestation of colorectal cancer in up to 29% of cases. The stent is auto-expandable diamond cell type, manufactured from a NiTi tube with 4.5 mm in diameter, in which longitudinal grooves were performed by cutting laser technique. The expansion process to the final shape was made by deformation in the martensite state. The stent reaches a high free expansion rate of 7, with a longitudinal variable radial strength and a bell-shaped profile in the extremes in order to avoid migration. Finite elements models were used for simulating the mechanical behaviour. The prototype was evaluated by implantation in a colon stenosis model of 6 mm in diameter performed in a porcine speciment. The stent gave a good deployment, fixation and capability to open the gap up to 15 mm in diameter. PMID:16179756

  3. Cell adhesion on NiTi thin film sputter-deposited meshes.

    PubMed

    Loger, K; Engel, A; Haupt, J; Li, Q; Lima de Miranda, R; Quandt, E; Lutter, G; Selhuber-Unkel, C

    2016-02-01

    Scaffolds for tissue engineering enable the possibility to fabricate and form biomedical implants in vitro, which fulfill special functionality in vivo. In this study, free-standing Nickel–Titanium(NiTi) thin film mesheswere produced by means of magnetron sputter deposition.Meshes contained precisely defined rhombic holes in the size of 440 to 1309 μm2 and a strut width ranging from 5.3 to 9.2 μm. The effective mechanical properties of the microstructured superelastic NiTi thin film were examined by tensile testing. These results will be adapted for the design of the holes in the film. The influence of hole and strut dimensions on the adhesion of sheep autologous cells (CD133+) was studied after 24 h and after seven days of incubation. Optical analysis using fluorescence microscopy and scanning electron microscopy showed that cell adhesion depends on the structural parameters of the mesh. After 7 days in cell culture a large part of the mesh was covered with aligned fibrous material. Cell adhesion is particularly facilitated on meshes with small rhombic holes of 440 μm2 and a strut width of 5.3 μm. Our results demonstrate that free-standing NiTi thin film meshes have a promising potential for applicationsin cardiovascular tissue engineering, particularly for the fabrication of heart valves. PMID:26652414

  4. Strain rate response of a Ni-Ti shape memory alloy after hydrogen charging

    NASA Astrophysics Data System (ADS)

    Gamaoun, Fehmi; Hassine, Tarak; Bouraoui, Tarak

    2014-01-01

    In this work, we investigate the susceptibility of Ni-Ti superelastic wires to the strain rates during tensile testing after hydrogen charging. Cathodic hydrogen charging is performed at a current density of 10 A/m² during 2-12 h in 0.9% NaCl solution and aged for 24 h at room temperature. Specimens underwent one cycle of loading-unloading reaching a stress value of 700 MPa. During loading, strain rates from 10-6 to 5 × 10-2 s-1 have been achieved. After 8 h of hydrogen charging, an embrittlement has been detected in the tensile strain rate range of 10-6 to 10-4 s-1. In contrast, no embrittlement has been detected for strain rates of 10-3 s-1 and higher. However, after 12 h of hydrogen charging and 24 h of annealing at room temperature, the embrittlement occurs in the beginning of the austenite-martensite transformation for all the studied strain rate values. These results show that for a range of critical amounts of diffused hydrogen, the embrittlement of the Ni-Ti superelastic alloy strongly depends on the strain rate during the tensile test. Moreover, it has been shown that this embrittlement occurs for low values of strain rates rather than the higher ones. This behaviour is attributed to the interaction between the diffused hydrogen and growth of the martensitic domain.

  5. Laser and Surface Processes of NiTi Shape Memory Elements for Micro-actuation

    NASA Astrophysics Data System (ADS)

    Nespoli, Adelaide; Biffi, Carlo Alberto; Previtali, Barbara; Villa, Elena; Tuissi, Ausonio

    2014-04-01

    In the current microtechnology for actuation field, shape memory alloys (SMA) are considered one of the best candidates for the production of mini/micro devices thanks to their high power-to-weight ratio as function of the actuator weight and hence for their capability of generating high mechanical performance in very limited spaces. In the microscale the most suitable conformation of a SMA actuator is given by a planar wavy formed arrangement, i.e., the snake-like shape, which allows high strokes, considerable forces, and devices with very low sizes. This uncommon and complex geometry becomes more difficult to be realized when the actuator dimensions are scaled down to micrometric values. In this work, micro-snake-like actuators are laser machined using a nanosecond pulsed fiber laser, starting from a 120- μm-thick NiTi sheet. Chemical and electrochemical surface polishes are also investigated for the removal of the thermal damages of the laser process. Calorimetric and thermo-mechanical tests are accomplished to assess the NiTi microdevice performance after each step of the working process. It is shown that laser machining has to be followed by some post-processes in order to obtain a micro-actuator with good thermo-mechanical properties.

  6. Synthesis and characterization of hybrid micro/nano-structured NiTi surfaces by a combination of etching and anodizing.

    PubMed

    Huan, Z; Fratila-Apachitei, L E; Apachitei, I; Duszczyk, J

    2014-02-01

    The purpose of this study was to generate hybrid micro/nano-structures on biomedical nickel-titanium alloy (NiTi). To achieve this, NiTi surfaces were firstly electrochemically etched and then anodized in fluoride-containing electrolyte. With the etching process, the NiTi surface was micro-roughened through the formation of micropits uniformly distributed over the entire surface. Following the subsequent anodizing process, self-organized nanotube structures enriched in TiO2 could be superimposed on the etched surface under specific conditions. Furthermore, the anodizing treatment significantly reduced water contact angles and increased the surface free energy compared to the surfaces prior to anodizing. The results of this study show for the first time that it is possible to create hybrid micro/nano-structures on biomedical NiTi alloys by combining electrochemical etching and anodizing under controlled conditions. These novel structures are expected to significantly enhance the surface biofunctionality of the material when compared to conventional implant devices with either micro- or nano-structured surfaces.

  7. Failure Analysis and Recovery of a 50-mm Highly Elastic Intermetallic NiTi Ball Bearing for an ISS Application

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Howard, S. Adam; Moore, Lewis

    2016-01-01

    Ball bearings used inside the ISS Distillation Assembly centrifuge require superior corrosion and shock resistance to withstand acidic wastewater exposure and heavy spacecraft launch related loads. These requirements challenge conventional steel bearings and provide an ideal pathfinder application for 50-mm bore, deep-groove ball bearings made from the corrosion immune and highly elastic intermetallic material 60NiTi. During early ground testing in 2014 one 60NiTi bearing unexpectedly and catastrophically failed after operating for only 200 hr. A second bearing running on the same shaft was completely unaffected. An investigation into the root cause of the failure determined that an excessively tight press fit of the bearing outer race coupled with NiTi's relatively low elastic modulus were key contributing factors. The proposed failure mode was successfully replicated by experiment. To further corroborate the root cause theory, a successful bearing life test using improved installation practices (selective fitting) was conducted. The results show that NiTi bearings are suitable for space applications provided that care is taken to accommodate their unique material characteristics.

  8. Fretting behavior of NiTi shape memory alloy against long bone in the imitated human physiological solution

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Xu, Y. T.; Xia, T. D.; Da, G. Z.

    2007-07-01

    The environment of orthopaedic implants sometimes induces vibrations at the contact of the modular prostheses components. In this paper the fretting behavior of NiTi SMAs against human bones in the imitated human physiological solution was studied at various displacement amplitudes and Ph value. Surface micrograph after fretting was observed by MEF3 microscope. Appearance of fretting scar was measured by 2206 roughness tester. The result shows that the friction coefficient between the bone and NiTi SMAs pairs declined due to the lubrication effect of Hank's solution, and which increased when Ph value of fluid was not 7.2 due to the corrosion. So the friction coefficient at acid and alkali Hank's solution is higher than those at the neutral solution and ambient air condition. Generally speaking, the friction coefficient between the bone and NiTi SMAs tend to be stable with the increasing amplitude at all test conditions. It is because that the surface was oxidized to restrain the forming of wear debris and the further development of fretting scars. Although the length and width of the wear scars in simulation body fluid are smaller than that at ambient air condition, the surface of NiTi SMAs damaged is characterized by deep scratches with debris particles within the contact area. Fretting regime of NiTi/bones pairs exhibits the mixed regime at ambient air condition and the slip regime in the Hank's solution.

  9. Effect of aging treatment on the in vitro nickel release from porous oxide layers on NiTi

    NASA Astrophysics Data System (ADS)

    Huan, Z.; Fratila-Apachitei, L. E.; Apachitei, I.; Duszczyk, J.

    2013-06-01

    Despite the ability of creating porous oxide layers on nickel-titanium alloy (NiTi) surface for biofunctionalization, the use of plasma electrolytic oxidation (PEO) has raised concerns over the possible increased levels of Ni release. Therefore, the primary aim of this study was to investigate the effect of aging in boiling water on Ni release from porous NiTi surfaces that have been formed by the PEO process. Based on different oxidation conditions, e.g. electrolyte composition and electrical parameters, three kinds of oxide layers with various characteristics were prepared on NiTi substrate. The process was followed by aging in boiling water for different durations. The Ni release was assessed by immersion tests in phosphate buffer saline and the Ni concentration was measured using the flame atomic absorption spectrometry. The results showed that aging in boiling water can significantly reduce the Ni release from oxidized porous samples, given that the duration of the treatment is finely adjusted according to the parameters of the as-formed oxide layer. Surface examination of the samples before and after aging in boiling water suggested that such a treatment is non-destructive while improving the corrosion resistance of oxidized samples, as evidenced by potentiodynamic polarization tests. The results of this study indicate that water boiling may be a suitable post-treatment required to minimize Ni release from porous oxides produced on NiTi by PEO for biomedical applications.

  10. Synthesis and characterization of hybrid micro/nano-structured NiTi surfaces by a combination of etching and anodizing

    NASA Astrophysics Data System (ADS)

    Huan, Z.; Fratila-Apachitei, L. E.; Apachitei, I.; Duszczyk, J.

    2014-02-01

    The purpose of this study was to generate hybrid micro/nano-structures on biomedical nickel-titanium alloy (NiTi). To achieve this, NiTi surfaces were firstly electrochemically etched and then anodized in fluoride-containing electrolyte. With the etching process, the NiTi surface was micro-roughened through the formation of micropits uniformly distributed over the entire surface. Following the subsequent anodizing process, self-organized nanotube structures enriched in TiO2 could be superimposed on the etched surface under specific conditions. Furthermore, the anodizing treatment significantly reduced water contact angles and increased the surface free energy compared to the surfaces prior to anodizing. The results of this study show for the first time that it is possible to create hybrid micro/nano-structures on biomedical NiTi alloys by combining electrochemical etching and anodizing under controlled conditions. These novel structures are expected to significantly enhance the surface biofunctionality of the material when compared to conventional implant devices with either micro- or nano-structured surfaces.

  11. Differential Effects of Legume Species on the Recovery of Soil Microbial Communities, and Carbon and Nitrogen Contents, in Abandoned Fields of the Loess Plateau, China

    NASA Astrophysics Data System (ADS)

    Li, Jin Hua; Jiao, Shu Mei; Gao, Rong Qing; Bardgett, Richard D.

    2012-12-01

    Plant-soil interactions are known to influence a wide range of ecosystem-level functions. Moreover, the recovery of these functions is of importance for the successful restoration of soils that have been degraded through intensive and/or inappropriate land use. Here, we assessed the effect of planting treatments commonly used to accelerate rates of grassland restoration, namely introduction of different legume species Medicago sativa, Astragalus adsurgens, Melilotus suaveolens, on the recovery of soil microbial communities and carbon and nitrogen contents in abandoned fields of the Loess Plateau, China. The results showed effects were species-specific, and either positive, neutral or negative depending on the measure and time-scale. All legumes increased basal respiration and metabolic quotient and had a positive effect on activity and functional diversity of the soil microbial community, measured using Biolog EcoPlate. However, soil under Astragalus adsurgens had the highest activity and functional diversity relative to the other treatments. Soil carbon and nitrogen content and microbial biomass were effectively restored in 3-5 years by introducing Medicago sativa and Astragalus adsurgens into early abandoned fields. Soil carbon and nitrogen content were retarded in 3-5 years and microbial biomass was retarded in the fifth year by introducing Melilotus suaveolens. Overall, the restoration practices of planting legumes can significantly affect soil carbon and nitrogen contents, and the biomass, activity, and functional diversity of soil microbial community. Therefore, we propose certain legume species could be used to accelerate ecological restoration of degraded soils, hence assist in the protection and preservation of the environment.

  12. Differential effects of legume species on the recovery of soil microbial communities, and carbon and nitrogen contents, in abandoned fields of the Loess Plateau, China.

    PubMed

    Li, Jin Hua; Jiao, Shu Mei; Gao, Rong Qing; Bardgett, Richard D

    2012-12-01

    Plant-soil interactions are known to influence a wide range of ecosystem-level functions. Moreover, the recovery of these functions is of importance for the successful restoration of soils that have been degraded through intensive and/or inappropriate land use. Here, we assessed the effect of planting treatments commonly used to accelerate rates of grassland restoration, namely introduction of different legume species Medicago sativa, Astragalus adsurgens, Melilotus suaveolens, on the recovery of soil microbial communities and carbon and nitrogen contents in abandoned fields of the Loess Plateau, China. The results showed effects were species-specific, and either positive, neutral or negative depending on the measure and time-scale. All legumes increased basal respiration and metabolic quotient and had a positive effect on activity and functional diversity of the soil microbial community, measured using Biolog EcoPlate. However, soil under Astragalus adsurgens had the highest activity and functional diversity relative to the other treatments. Soil carbon and nitrogen content and microbial biomass were effectively restored in 3-5 years by introducing Medicago sativa and Astragalus adsurgens into early abandoned fields. Soil carbon and nitrogen content were retarded in 3-5 years and microbial biomass was retarded in the fifth year by introducing Melilotus suaveolens. Overall, the restoration practices of planting legumes can significantly affect soil carbon and nitrogen contents, and the biomass, activity, and functional diversity of soil microbial community. Therefore, we propose certain legume species could be used to accelerate ecological restoration of degraded soils, hence assist in the protection and preservation of the environment.

  13. The effects of land abandonment and long-term afforestation practices on the organic carbon and lignin content of a Mediteranean soil

    NASA Astrophysics Data System (ADS)

    Stijsiger, Romy; Nadal-Romero, Estela; Campo, Julian; Cammeraat, Erik

    2016-04-01

    Afforestation is an important strategy that can decrease atmospheric carbon in sequestering it in biomass and soils (Pérez-Crusado et al., 2014). In Spain an active afforestation program was adopted in the 1950s, when after wide spread land abandonment the soils were severely eroded (FAO, 2015). In this research the organic carbon and lignin content of the soils in the Araguás catchment area in the Spanish Pyrenees were examined. This research is part of a larger research examining the effect of afforestation over time (Med Afforest Project, PIEF-GA-2013-624974). The research area was afforested with both the P. sylvestris (Scotts Pine) and the P.nigra (Black Pine). Both sites were compared to bare soil (representing severely eroded soil), natural secondary succession (re-vegetation) and meadows. The method used to assess the lignin content is Curie-point pyrolysis with tetramethylammonium hydroxide (TMAH). The results showed a reducing trend for the soil organic carbon (SOC) content with depth. The highest SOC and lignin contents in the topsoil were found under P.nigra and secondary succession. This decline in lignin content corresponds with a high degradation rate (Ad/Al) in the top soil and lower degradation rates in depths of >20 cm. Meadows showed an increased SOC content in deeper horizons, which corresponds to high lignin content as well. In which the meadows showed an increase in lignin content for the soil depths of >20 cm that was unusual and could not be explained by the S/G and P/G ratios and the degradation ratio (Ad/Al). According to the results, P. nigra was the best afforestation practice for increasing the SOC and lignin contents in the soil. The P. sylvestris was considered but proved to be less successful than natural secondary succession. Acknowledgements This research was supported by a Marie Curie Intra-European Fellowship in the project "MED-AFFOREST" (PIEF-GA-2013-624974). JC also acknowledges the VALi+d postdoctoral contract (APOSTD/2014

  14. The overexpression of the pine transcription factor PpDof5 in Arabidopsis leads to increased lignin content and affects carbon and nitrogen metabolism.

    PubMed

    Rueda-López, Marina; Cañas, Rafael A; Canales, Javier; Cánovas, Francisco M; Ávila, Concepción

    2015-12-01

    PpDof 5 is a regulator of the expression of glutamine synthetase (GS; EC 6.3.1.2) genes in photosynthetic and non-photosynthetic tissues of maritime pine. We have used Arabidopsis thaliana as a model system to study PpDof 5 function in planta, generating transgenic lines overexpressing the pine transcription factor. The overexpression of PpDof 5 resulted in a substantial increase of lignin content with a simultaneous regulation of carbon and nitrogen key genes. In addition, partitioning in carbon and nitrogen compounds was spread via various secondary metabolic pathways. These results suggest pleiotropic effects of PpDof 5 expression on various metabolic pathways of carbon and nitrogen metabolism. Plants overexpressing PpDof 5 exhibited upregulation of genes encoding enzymes for sucrose and starch biosynthesis, with a parallel increase in the content of soluble sugars. When the plants were grown under nitrate as the sole nitrogen source, they exhibited a significant regulation of the expression of genes involved mainly in signaling, but similar growth rates to wild-type plants. However, plants grown under ammonium exhibited major induction of the expression of photosynthetic genes and differential expression of ammonium and nitrate transporters. All these data suggest that in addition to controlling ammonium assimilation, PpDof 5 could be also involved in the regulation of other pathways in carbon and nitrogen metabolism in pine trees. PMID:26333592

  15. Distribution of polycyclic aromatic hydrocarbons in different size fractions of soil from a coke oven plant and its relationship to organic carbon content.

    PubMed

    Li, Helian; Chen, Jiajun; Wu, Wei; Piao, Xuesong

    2010-04-15

    The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in US EPA priority list were analyzed in the bulk and six particle size fractions of soil samples from a coke oven plant. The relationships of PAHs concentrations with total organic carbon (TOC), black carbon (BC) and other forms of organic carbon (OC) contents have been investigated. Total PAH concentrations ranged from 6.27 to 40.18 mg kg(-1) dry weight. The highest total PAH concentration occurred in the 250-500 microm size fraction. The maximum individual PAH concentration was in the 250-500 microm or 500-2000 microm size fraction. The size fractions of 125-500 microm and <50 microm have higher percentages and contributed 24.62% and 23.33% of the total PAH mass, respectively. The relative abundance of individual PAH compounds and PAH molecular indices present typical characteristic pyrogenic origin. The maximal TOC and BC contents were found in the 125-250 microm size fraction. Strong positive linear relationship between total PAH concentration and TOC or BC has been demonstrated, with a linear regression coefficient value of 0.7277 and 0.9245, respectively. The linear relationship between total PAH concentration versus OC (OC = TOC - BC) is weaker than that versus TOC or BC, with a correlation coefficient of 0.4117. It indicates that partitioned in organic matter, especially in black carbon is the dominant form of PAHs in the soil. PMID:20031305

  16. Minor-element composition and organic carbon content of marine and nonmarine shales of Late Cretaceous age in the western interior of the United States

    USGS Publications Warehouse

    Tourtelot, H.A.

    1964-01-01

    The composition of nonmarine shales of Cretaceous age that contain less than 1 per cent organic carbon is assumed to represent the inherited minor-element composition of clayey sediments delivered to the Cretaceous sea that occupied the western interior region of North America. Differences in minor-element content between these samples and samples of 1. (a) nonmarine carbonaceous shales (1 to 17 per cent organic carbon), 2. (b) nearshore marine shales (less than 1 per cent organic carbon), and 3. (c) offshore marine shales (as much as 8 per cent organic carbon), all of the same age, reveal certain aspects of the role played by clay minerals and organic materials in affecting the minor-element composition of the rocks. The organic carbon in the nonmarine rocks occurs in disseminated coaly plant remains. The organic carbon in the marine rocks occurs predominantly in humic material derived from terrestrial plants. The close similarity in composition between the organic isolates from the marine samples and low-rank coal suggests that the amount of marine organic material in these rocks is small. The minor-element content of the two kinds of nonmarine shales is the same despite the relatively large amount of organic carbon in the carbonaceous shales. The nearshore marine shales, however, contain larger median amounts of arsenic, boron, chromium, vanadium and zinc than do the nonmarine rocks; and the offshore marine shales contain even larger amounts of these elements. Cobalt, molybdenum, lead and zirconium show insignificant differences in median content between the nonmarine and marine rocks, although as much as 25 ppm molybdenum is present in some offshore marine samples. The gallium content is lower in the marine than in the nonmarine samples. Copper and selenium contents of the two kinds of nonmarine rocks and the nearshore marine samples are the same, but those of the offshore samples are larger. In general, arsenic, chromium, copper, molybdenum, selenium, vanadium

  17. Effect of Surface Alloying by Silicon on the Corrosion Resistance and Biocompatibility of the Binary NiTi

    NASA Astrophysics Data System (ADS)

    Psakhie, S. G.; Meisner, S. N.; Lotkov, A. I.; Meisner, L. L.; Tverdokhlebova, A. V.

    2014-07-01

    This paper presents the study on changes in element and phase compositions in the near-surface layer and on surface topography of the NiTi specimens after the silicon ion-beam treatment. The effect of these parameters of the near-surface layer on corrosion properties in biochemical solutions and biocompatibility with mesenchymal stem cells of rat marrow is studied. Ion-beam surface modification of the specimens was performed by a DIANA-3 implanter (Tomsk, Russia), using single-ion-beam pulses under oil-free pumping and high vacuum (10-4 Pa) conditions in a high-dose ion implantation regime. The fluence made 2 × 1017 cm-2, at an average accelerating voltage of 60 kV, and pulse repetition frequency of 50 Hz. The silicon ion-beam treatment of specimen surfaces is shown to bring about a nearly twofold improvement in the corrosion resistance of the material to attack by aqueous solutions of NaCl (artificial body fluid) and human plasma and a drastic decrease in the nickel concentration after immersion of the specimens into the solutions for ~3400 and ~6000 h, respectively (for the artificial plasma solution, a nearly 20-fold decrease in the Ni concentration is observed). It is shown that improvement of NiTi corrosion resistance after treatment by Si ions occurs mainly due to the formation of two-layer composite coating based on Ti oxides (outer layer) on the NiTi surface and adjacent inner layer of oxides, carbides, and silicides of the NiTi alloy components. Inner layer with high silicon concentration serves as a barrier layer preventing nickel penetration into biomedium. This, in our opinion, is the main reason why the NiTi alloy exhibits no cytotoxic properties after ion modification of its surface and leads to the biocompatibility improvement at the cellular level, respectively.

  18. The Effect of Pre-Stressing on the Static Indentation Load Capacity of the Superelastic 60NiTi

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2013-01-01

    Superelastic nickel-titanium alloys, such as 60NiTi (60Ni-40Ti by wt.%), are under development for use in mechanical components like rolling element bearings and gears. Compared to traditional bearing steels, these intermetallic alloys, when properly heat-treated, are hard but exhibit much lower elastic modulus (approx.100 GPa) and a much broader elastic deformation range (approx.3 percent or more). These material characteristics lead to high indentation static load capacity, which is important for certain applications especially space mechanisms. To ensure the maximum degree of elastic behavior, superelastic materials must be pre-stressed, a process referred to as "training" in shape memory effect (SME) terminology, at loads and stresses beyond expected use conditions. In this paper, static indentation load capacity tests are employed to assess the effects of pre-stressing on elastic response behavior of 60NiTi. The static load capacity is measured by pressing 12.7 mm diameter ceramic Si3N4 balls into highly polished, hardened 60NiTi flat plates that have previously been exposed to varying levels of pre-stress (up to 2.7 GPa) to determine the load that results in shallow but measurable (0.6 m, 25 in. deep) permanent dents. Hertz stress calculations are used to estimate contact stress. Without exposure to pre-stress, the 60NiTi surface can withstand an approximately 3400 kN load before significant denting (>0.4 m deep) occurs. When pre-stressed to 2.7 GPa, a static load of 4900 kN is required to achieve a comparable dent, a 30 percent increase. These results suggest that stressing contact surfaces prior to use enhances the static indentation load capacity of the superelastic 60NiTi. This approach may be adaptable to the engineering and manufacture of highly resilient mechanical components such as rolling element bearings.

  19. Experimental carbon dioxide laser brain lesions and intracranial dynamics. Part 2. Effect on brain water content and its response to acute therapy

    SciTech Connect

    Tiznado, E.G.; James, H.E.; Moore, S.

    1985-04-01

    Experimental brain lesions were created over the left parietooccipital cortex of the albino rabbit through the intact dura mater with high radiating carbon dioxide laser energy. The brain water content was studied 2, 6, and 24 hours after the insult. Another two groups of animals received acute therapy with either dexamethasone (1 mg/kg) or furosemide (1 mg/kg). In all groups, Evans blue extravasation uniformly extended from the impact crater into the surrounding white matter. The brain water content in the gray matter was elevated from the control value by 2 hours after impact and remained elevated at 6 and 24 hours. The white matter brain water content did not increase until 6 hours after impact and remained elevated in the 24-hour group. After dexamethasone treatment, there was a significant decrease of water in the gray matter, but not in the white matter. With furosemide therapy, there was no reduction of gray or white matter brain water.

  20. Spatial and temporal changes of soil organic carbon content since time of reclamation of mine soils in a semi-arid environment of Australia

    NASA Astrophysics Data System (ADS)

    Baumgartl, Thomas; Glenn, Vanessa; Erskine, Peter; Chan, Jaclyn

    2016-04-01

    Quantifying carbon fluxes in reclaimed mining environments informs about the success of rehabilitation. Increasing soil organic matter (SOM) improves crucial functional properties of soil; thus, it is highly desirable to promote SOM accumulation in rehabilitated mine soils. The carbon content is often used as a surrogate to describe the status of soil health. Organic carbon in soils contributes to nutrient storage and exchange for plant growth, but also improves water storage capacity and microbial activity. Particularly for poor quality soil substrates with low clay contents, like many spoils from open-cut mining, elevating the carbon concentration is an ideal means to improve the soil quality. The objective of the study was to investigate the change of SOC of re-established soils in mining dependent on the length of time since reclamation under different types of vegetation communities in a semi-arid environment of Central Queensland, Australia. Deviating from standard sampling programs, the SOC of the soil profile was determined in small depth sampling increments from the surface following the assumption, that fresh (green) organic matter will be highest close to the surface and that in semi-arid environments, the dislocation of organic matter to depth by precipitation and microbial activity will be limited. The investigations showed that the most recently rehabilitated sites (>3 years post rehabilitation) show a high organic carbon (OC) gradient decreasing from the surface downwards into the soil. The highest concentration of OC was generally found in the first cm from the surface. Below a depth of 5cm no increase of OC with time since reclamation (max. 25 years) could be determined. An increase of OC with time could be determined, although it appears that even after more than 20 years since reclamation the concentration and depth distribution of OC of an unmined soil could not be rebuilt. Thus, it may be inferred that introducing support practices of

  1. Effects of land use and mineral characteristics on the organic carbon content, and the amount and composition of Na-pyrophosphate soluble organic matter in subsurface soils

    NASA Astrophysics Data System (ADS)

    Ellerbrock, R.; Kaiser, M.; Walter, K.; Sommer, M.

    2010-12-01

    Land use and mineral characteristics affect the balance of organic carbon in surface as well as in subsurface soils and related feedbacks on soil functions like their potential to mitigate the greenhouse effect. Actually, there are less information about the effects of land use as well as soil properties on the amount and composition of organic matter (OM) for subsurface soils as compared to surface soils. Here we aimed to analyze the long-term impact of arable and forest land use and soil mineral characteristics on subsurface soil organic carbon (SOC) contents, as well as on amount and composition of OM sequentially separated by Na-pyrophosphate solution (OM(PY)) from subsurface soil samples. Seven soils different in mineral characteristics were selected within Germany. Soil samples were taken from subsurface horizons of forest and adjacent arable sites continuously used >100 years. The OM(PY) fractions were analysed on their OC content (OCPY) and characterized by FTIR spectroscopy. A distinct influence of the long-term land use on the SOC contents could not be detected because only for four out of seven sites the forest subsurface soils showed larger SOC contents than the adjacent agricultural soils. A generally site independent enhanced OC sequestration in subsurface soils due to differences in land use cannot be expected in the long-term. Multiple regression analyses indicated for the arable subsurface soils significant positive relationships between the SOC contents and combined effects of the i) exchangeable Ca (Caex) and oxalate soluble Fe (Feox), and ii) the Caex and Alox contents. For the arable subsurface soils the increase of OCPY* (OCPY multiplied by the relative C=O content of OM(PY)) by increasing contents of Caex indicated that OM(PY) mainly interacts with Ca2+ cations. For the forest subsurface soils (pH <5), the OCPY contents were found to be related to the contents of Na-pyrophosphate soluble Fe and Al. The long-term arable and forest land use

  2. Surface nanomechanical behavior of ZrN and ZrCN films deposited on NiTi shape memory alloy by magnetron sputtering.

    PubMed

    Chu, C L; Ji, H L; Guo, C; Sheng, X B; Dong, Y S; Lin, P H; Hu, T; Chu, P K

    2011-12-01

    Surface nanomechanical behavior under nanoindentation of ZrN and ZrCN film on NiTi substrate was studied. The surface hardness and modulus of the films increase initially with larger nanoindentation depths and then reach their maximum values. Afterwards, they diminish gradually and finally reaching plateau values which are the composite modulus and composite hardness derived from the ZrN/ZrCN film and NiTi substrate. They are higher than those of electropolished NiTi SMA due to the properties of ZrN and ZrCN. In comparison, the surface nanomechanical properties of electropolished NiTi exhibit a different change with depths. PMID:22409080

  3. Testing of an automated online EA-IRMS method for fast and simultaneous carbon content and stable isotope measurement of aerosol samples

    NASA Astrophysics Data System (ADS)

    Major, István; Gyökös, Brigitta; Túri, Marianna; Futó, István; Filep, Ágnes; Hoffer, András; Molnár, Mihály

    2016-04-01

    Comprehensive atmospheric studies have demonstrated that carbonaceous aerosol is one of the main components of atmospheric particulate matter over Europe. Various methods, considering optical or thermal properties, have been developed for quantification of the accurate amount of both organic and elemental carbon constituents of atmospheric aerosol. The aim of our work was to develop an alternative fast and easy method for determination of the total carbon content of individual aerosol samples collected on prebaked quartz filters whereby the mass and surface concentration becomes simply computable. We applied the conventional "elemental analyzer (EA) coupled online with an isotope ratio mass spectrometer (IRMS)" technique which is ubiquitously used in mass spectrometry. Using this technique we are able to measure simultaneously the carbon stable isotope ratio of the samples, as well. During the developing process, we compared the EA-IRMS technique with an off-line catalytic combustion method worked out previously at Hertelendi Laboratory of Environmental Studies (HEKAL). We tested the combined online total carbon content and stable isotope ratio measurement both on standard materials and real aerosol samples. Regarding the test results the novel method assures, on the one hand, at least 95% of carbon recovery yield in a broad total carbon mass range (between 100 and 3000 ug) and, on the other hand, a good reproducibility of stable isotope measurements with an uncertainty of ± 0.2 per mill. Comparing the total carbon results obtained by the EA-IRMS and the off-line catalytic combustion method we found a very good correlation (R2=0.94) that proves the applicability of both preparation method. Advantages of the novel method are the fast and simplified sample preparation steps and the fully automated, simultaneous carbon stable isotope ratio measurement processes. Furthermore stable isotope ratio results can effectively be applied in the source apportionment

  4. Spatial prediction of Soil Organic Carbon contents in croplands, grasslands and forests using environmental covariates and Generalized Additive Models (Southern Belgium)

    NASA Astrophysics Data System (ADS)

    Chartin, Caroline; Stevens, Antoine; van Wesemael, Bas

    2015-04-01

    Providing spatially continuous Soil Organic Carbon data (SOC) is needed to support decisions regarding soil management, and inform the political debate with quantified estimates of the status and change of the soil resource. Digital Soil Mapping techniques are based on relations existing between a soil parameter (measured at different locations in space at a defined period) and relevant covariates (spatially continuous data) that are factors controlling soil formation and explaining the spatial variability of the target variable. This study aimed at apply DSM techniques to recent SOC content measurements (2005-2013) in three different landuses, i.e. cropland, grassland, and forest, in the Walloon region (Southern Belgium). For this purpose, SOC databases of two regional Soil Monitoring Networks (CARBOSOL for croplands and grasslands, and IPRFW for forests) were first harmonized, totalising about 1,220 observations. Median values of SOC content for croplands, grasslands, and forests, are respectively of 12.8, 29.0, and 43.1 g C kg-1. Then, a set of spatial layers were prepared with a resolution of 40 meters and with the same grid topology, containing environmental covariates such as, landuses, Digital Elevation Model and its derivatives, soil texture, C factor, carbon inputs by manure, and climate. Here, in addition to the three classical texture classes (clays, silt, and sand), we tested the use of clays + fine silt content (particles < 20 µm and related to stable carbon fraction) as soil covariate explaining SOC variations. For each of the three land uses (cropland, grassland and forest), a Generalized Additive Model (GAM) was calibrated on two thirds of respective dataset. The remaining samples were assigned to a test set to assess model performance. A backward stepwise procedure was followed to select the relevant environmental covariates using their approximate p-values (the level of significance was set at p < 0.05). Standard errors were estimated for each of

  5. Revealing spatial distribution of soil organic carbon contents and stocks of a disturbed bog relict by in-situ NIR and apparent EC mapping

    NASA Astrophysics Data System (ADS)

    Bechtold, Michel; Tiemeyer, Bärbel; Don, Axel; Altdorff, Daniel; van der Kruk, Jan; Huisman, Johan A.

    2013-04-01

    Previous studies showed that in-situ visible near-infrared (vis-NIR) spectroscopy can overcome the limitations of conventional soil sampling. Costs can be reduced and spatial resolution enhanced when mapping field-scale variability of soil organic carbon (SOC). Detailed maps can help to improve SOC management and lead to better estimates of field-scale total carbon stocks. Knowledge of SOC field patterns may also help to reveal processes and factors controlling SOC variability. In this study, we apply in situ vis-NIR and apparent electrical conductivity (ECa) mapping to a disturbed bog relict. The major question of this application study was how field-scale in-situ vis-NIR mapping performs for a very heterogeneous area and under difficult grassland conditions and under highly-variable water content conditions. Past intensive peat cutting and deep ploughing in some areas, in combination with a high background heterogeneity of the underlying mineral sediments, have led to a high variability of SOC content (5.6 to 41.3 %), peat layer thickness (25 to 60 cm) and peat degradation states (from nearly fresh to amorphous). Using a field system developed by Veris Technologies (Salina KS, USA), we continuously collected vis-NIR spectra at 10 cm depth (measurement range: 350 nm to 2200 nm) over an area of around 12 ha with a line spacing of about 12 m. The system includes a set of discs for measuring ECa of the first 30 and 90 cm of the soil. The same area was also mapped with a non-invasive electro-magnetic induction (EMI) setup that provided ECa data of the first 25, 50 and 100 cm. For calibration and validation of the spatial data, we took 30 representative soil samples and 15 soil cores of about 90 cm depth, for which peat thickness, water content, pore water EC, bulk density (BD), as well as C and N content were determined for various depths. Preliminary results of the calibration of the NIR spectra to the near-surface SOC contents indicate good data quality despite the

  6. The role of fungi for carbon decomposition in soils of different structure and fresh organic matter content

    NASA Astrophysics Data System (ADS)

    Schmidt, Sonja; Chenu, Claire; Falconer, Ruth; Geradin, Cyril; Nunan, Naoise; Otten, Wilfred; Pouteau, Valerie

    2014-05-01

    Sequestration of C in soils has a major influence on climate change. Fungi play an important role in carbon decomposition and sequestration but the effect of soil structure and input of fresh organic matter (particulate organic matter POM) is still unclear. Fungi is predominant involved in cellulose decomposition and the priming effect (PE) where old SOM is decomposed by using fresh carbon as a source of energy. Information on how soil structure affects colonisation and decomposition of POM and SOM by fungi could help to get explain processes involved in carbon sequestration and CO2respiration. The objective of this study was to get a better understanding on the involvement of fungi in CO2 emissions arising from soils and to gain information on what factors in the soil are driving organic matter (OM) decomposition. Experimental data on fungal growth and carbon decomposition as affected by POM abundance and soil structure were obtained. Sterilised maize straw (1-2 mm2) and soil (

  7. Effects of tillage on contents of organic carbon, nitrogen, water-stable aggregates and light fraction for four different long-term trials

    NASA Astrophysics Data System (ADS)

    Andruschkewitsch, R.; Geisseler, D.; Koch, H.-J.; Ludwig, B.

    2012-04-01

    Despite increasing interest in tillage techniques as a factor affecting organic carbon (Corg) dynamics and stabilization mechanisms little is known about the underlying processes. Our objectives were (i) to quantify the impact of different tillage treatments on the amount and distribution of of labile Corg pools, on the water-stable macro-aggregate (>250 µm) contents and on organic carbon (Corg) storage and (ii) to quantify the ability of soils under different tillage treatments, light fraction (LF) inputs and clay contents in macro-aggregate formation. Therefore four long-term tillage trials on loess soil in Germany with regular conventional tillage (CT, to 30 cm), mulch tillage (MT, to 10 cm), and no-tillage (NT) treatments. Samples were taken in 0-5 cm, 5-25 cm and 25-40 cm depth after 18-25 years of different tillage treatments and investigated on free and occluded LF (fLF and oLF, respectively) and on macro-aggregate contents. Furthermore an incubation experiment for the quantifcation of macro-aggregate formation was conducted. Macro-aggregates in soils from CT and NT treatments (0-5 and 5-25 cm soil depth) were destroyed and different amounts of light fraction (LF) and clay were applied. The four long-term tillage trials, differing in texture and climatic conditions, revealed consistent results in Corg storage among each other. Based on the equivalent soil mass approach (CT: 0-40, MT: 0-38, NT: 0-36 cm) the Corg stocks in the sampled profile were significantly higher for the MT treatment than for the CT and NT treatments. Significantly lower Corg, fLF, oLF, and macro-aggregate contents for the soils under CT treatment in comparison with the soils under NT and MT treatments were restricted on the top 5 cm. The correlation of the macro-aggregate content against the fLF and oLF contents suggested that the macro-aggregate content is influenced to a lesser extent directly by the physical impact of the different tillage treatments but by the contents of available

  8. 59 FR- CONTENTS

    Code of Federal Regulations, 2010 CFR

    1994-10-25

    ... From the Federal Register Online via the Government Printing Office ] CONTENTS Vol. 59, No. 205 Tuesday, October 25, 1994 Agricultural Marketing Service RULES Kiwifruit grown in California, 53563-53565... carbon monoxide content; report availability, 53650 Premerger notification waiting periods;...

  9. On the Mechanisms for Martensite Formation in YAG Laser Welded Austenitic NiTi

    NASA Astrophysics Data System (ADS)

    Oliveira, J. P.; Braz Fernandes, F. M.; Miranda, R. M.; Schell, N.

    2016-03-01

    Extensive work has been reported on the microstructure of laser-welded NiTi alloys either superelastic or with shape memory effect, motivated by the fact that the microstructure affects the functional properties. However, some effects of laser beam/material interaction with these alloys have not yet been discussed. This paper aims to discuss the mechanisms for the occurrence of martensite in the heat-affected zone and in the fusion zone at room temperature, while the base material is fully austenitic. For this purpose, synchrotron radiation was used together with a simple thermal analytic mathematical model. Two distinct mechanisms are proposed for the presence of martensite in different zones of a weld, which affects the mechanical and functional behavior of a welded component.

  10. Spallation in NiTi under One-Dimensional Shock Loading

    SciTech Connect

    Wallwork, A.; Workman, A.; Meziere, Y. J. E.; Millett, J. C. F.; Bourne, N. K.

    2006-07-28

    The dynamic response of the shape memory alloy NiTi has been of interest to a number of investigators because it displays a shape memory effect. The dynamic tensile (spall) strength of this material is measured under one-dimensional shock loading. The loading stress pulse length and impact stress were varied to a peak stress of 15 GPa. The pull back stress ({sigma}pbs) was found to increase with the applied pulse length. This suggests that the dynamic tensile strength is dependent upon the generation of a deformation micro structure that evolves behind the shock front. In contrast, increasing stress levels result in a near-constant pull back stress, although at the lowest applied stress, spallation did not occur.

  11. Microstructure, Cyclic Deformation and Corrosion Behavior of Laser Welded NiTi Shape Memory Wires

    NASA Astrophysics Data System (ADS)

    Mirshekari, G. R.; Kermanpur, A.; Saatchi, A.; Sadrnezhaad, S. K.; Soleymani, A. P.

    2015-09-01

    The present paper reports the effects of Nd:YAG laser welding on the microstructure, phase transformation, cyclic deformation behavior, and corrosion resistance of Ti-55 wt.% Ni wire. The results showed that the laser welding altered the microstructure of the weld metal which mainly composed of columnar dendrites grown epitaxially from the fusion line. DSC results indicated that the onset of the transformation temperatures of the weld metal differed from that of the base metal. Cyclic stress-strain behavior of laser-welded NiTi wire was comparable to the as-received material; while a little reduction in the pseudo-elastic property was noted. The weld metal exhibited higher corrosion potential, lower corrosion current density, higher breakdown potential and wider passive region than the base metal. The weld metal was therefore more resistant to corrosion than the base metal.

  12. Rheological study of feed stock for NiTi alloy molded parts

    NASA Astrophysics Data System (ADS)

    Subuki, I.; Abdullah, Z.; Razali, R.; Ismail, M. H.

    2015-12-01

    A rheological behaviour of the powder-binder mixture is one of essential analysis upon to success of Metal Injection Moulding (MIM) process. The purpose of this experimental work is to investigate the rheological behavior of feedstock containing mixtures of elemental Ni and Ti powders mixed with composite binder of palm stearin (PS) and polyethylene (PE) binder system. An equiatomic Ni-Ti (50-50) ratio was used in the present work for all formulations owing to excellent shape memory behaviour. The experimental rheological result indicated that all the feedstocks exhibited pseudo plastic flow behaviour; viscosity decreasing with temperature and shear rate. Increasing the powder loading resulted in higher viscosity, particularly at the low-range of shear rate. Owing to pseudo-plastic flow, it was found that the feedstock prepared exhibit promising rheological properties, thus resulting successfully injection moulding at an optimum temperature of 130°C.

  13. Influence of Surface Morphology on the Torsion Fracture of NiTi Endodontic Instruments

    NASA Astrophysics Data System (ADS)

    Elias, Carlos; Lopes, Helio; Vieira, Victor; Souza, Leticia; Vieira, Márcia

    2014-07-01

    This study analyzed the influences of manufacturing process (twisting and machining) and surface finishing on the angular distortion, maximum torque, and toughness of two NiTi endodontic instruments (Race—FKG Dentaire and TF—Twisted Files, SybronEndo). Statistical analysis of results showed that TF instruments (twisted) had higher distortion angle ( p < 0.05) and lower maximum torque to fracture ( p < 0.05) than Race instruments (machined). SEM analysis of fractured instruments showed a surface morphology characteristic of ductile fracture, with plastic deformation in the helical shafts. The results suggest that both instruments are equally suitable for clinical applications. This study is purely scientific as it evaluates only some material properties, and is not intended to endorse a commercial product.

  14. Effects of surface finish and mechanical training on Ni-Ti sheets for elastocaloric cooling

    NASA Astrophysics Data System (ADS)

    Engelbrecht, Kurt; Tušek, Jaka; Sanna, Simone; Eriksen, Dan; Mishin, Oleg V.; Bahl, Christian R. H.; Pryds, Nini

    2016-06-01

    Elastocaloric cooling has emerged as a promising alternative to vapor compression in recent years. Although the technology has the potential to be more efficient than current technologies, there are many technical challenges that must be overcome to realize devices with high performance and acceptable durability. We study the effects of surface finish and training techniques on dog bone shaped polycrystalline samples of NiTi. The fatigue life of several samples with four different surface finishes was measured and it was shown that a smooth surface, especially at the edges, greatly improved fatigue life. The effects of training both on the structure of the materials and the thermal response to an applied strain was studied. The load profile for the first few cycles was shown to change the thermal response to strain, the structure of the material at failure while the final structure of the material was weakly influenced by the surface finish.

  15. Spray Forming of NiTi and NiTiPd Shape-Memory Alloys

    NASA Technical Reports Server (NTRS)

    Mabe, James; Ruggeri, Robert; Noebe, Ronald

    2008-01-01

    In the work to be presented, vacuum plasma spray forming has been used as a process to deposit and consolidate prealloyed NiTi and NiTiPd powders into near net shape actuators. Testing showed that excellent shape memory behavior could be developed in the deposited materials and the investigation proved that VPS forming could be a means to directly form a wide range of shape memory alloy components. The results of DSC characterization and actual actuation test results will be presented demonstrating the behavior of a Nitinol 55 alloy and a higher transition temperature NiTiPd alloy in the form of torque tube actuators that could be used in aircraft and aerospace controls.

  16. The influence of Si as reactive bonding agent in the electrophoretic coatings of HA-Si-MWCNTs on NiTi alloys

    NASA Astrophysics Data System (ADS)

    Khalili, Vida; Khalil-Allafi, Jafar; Maleki-Ghaleh, Hossein; Paulsen, Alexander; Frenzel, Jan; Eggeler, Gunther

    2016-02-01

    In this study, different composite coatings with 20 wt.% silicon and 1 wt.% multi-walled carbon nanotubes of hydroxyapatite were developed on NiTi substrate using a combination of electrophoretic deposition and reactive bonding during the sintering. Silicon was used as reactive bonding agent. During electrophoretic deposition, the constant voltage of 30 V was applied for 60 s. After deposition, samples were dried and then sintered at 850 °C for 1 h in a vacuum furnace. SEM, XRD and EDX were used to characterize the microstructure, phase and elemental identification of coatings, respectively. The SEM images of the coatings reveal a uniform and compact structure for HA-Si and HA-Si-MWCNTs. The presence of silicon as a reactive bonding agent as well as formation of new phases such as SiO2, CaSiO3 and Ca3SiO5 during the sintering process results in compact coatings and consumes produced phases from HA decomposition. Formation of the mentioned phases was confirmed using XRD analysis. The EDX elemental maps show a homogeneous distribution of silicon all over the composite coatings. Also, the bonding strength of HA-Si-MWCNTs coating is found to be 27.47 ± 1 MPa.

  17. Failure of ProTaper rotary Ni-Ti instruments used by undergraduate students

    PubMed Central

    Duran-Sindreu, Fernando; Morello-Castro, Sergio; Mercade-Bellido, Montserrat; Bueno-Martínez, Rufino; Roig-Cayón, Miguel

    2012-01-01

    Objective: To evaluate the effect of number of uses, angle and radius of curvature and type of instrument on the fracture of ProTaper rotary instruments when used by undergraduate students. Study Design: Three hundred and seventy-six molars, with a total of 1114 root canals, extracted were instrumented by undergraduate students using ProTaper instruments according to the manufacturer´s recommendations. When fracture occurred, data were collected concerning the number of uses, type of instrument, level of fracture, angle and radius of curvature. ANOVA test were used to determine the influence of type of instrument in the incidence of instrument fracture. Logistic regression model was used to determine the influence of number of uses, angle and radius of curvature in the incidence of instrument fracture. Significance was set at p< 0.05. Results: A total of 37 Ni-Ti rotary instruments fractured during the treatment. Fracture occurred in 9.84% (37/376) of the teeth treated and 3.32% of the canals prepared with Ni-Ti rotary instruments (37/1114). A decrease in the radius of curvature of the canal significantly increased the likelihood of fracture (p=0.0001). Instrument fracture significantly increased as the number of uses increased (p=0.0037). No significant differences were found between the 6 types of ProTaper instruments (p=0.8). A reduction in the angle of curvature did not produce a significant decrease in the incidence of instrument separation (p=0.08). Conclusions: The results of this study imply that instrument fracture is linked to radius of curvature and number of uses. Key words:Fracture, ProTaper ®, root canal preparation, undergraduate students. PMID:24558555

  18. Ion irradiation induced solid-state amorphous reaction in Ni/Ti multilayers

    NASA Astrophysics Data System (ADS)

    Milosavljević, Momir; Toprek, Dragan; Obradović, Marko; Grce, Ana; Peruško, Davor; Dražič, Goran; Kovač, Janez; Homewood, Kevin P.

    2013-03-01

    The effects of Ar ion irradiation on interfacial reactions induced in Ni/Ti multilayers were investigated. Structures consisting of 10 alternate Ni (˜26 nm) and Ti (˜20 nm) layers of a total thickness ˜230 nm were deposited by ion sputtering on Si (1 0 0) wafers. Argon irradiations were done at 180 keV, to the doses of 1-6 × 1016 ions/cm2, the samples being held at room temperature. The projected implanted ion range is 86 ± 36 nm, maximum energy loss is closer to the surface, and maximum displacements per atom (dpa) from 47 to 284 for Ni and 26 to 156 for Ti. Characterizations of samples were performed by transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS). It is shown that ion irradiation induced a progressed intermixing in the mostly affected zone already for the lowest dose, the thickness of the mix increasing linearly with the irradiation dose. The mixed phase is fully amorphous, starting with a higher concentration of Ni (which is the diffusing species) from the initial stages, and saturating at Ni:Ti˜66:34. A thick amorphous layer (˜127 nm) formed towards the surface region of the structure for the irradiation dose of 4 × 1016 ions/cm2 remains stable with increasing the dose to 6 × 1016 ions/cm2, which introduces up to 6-7 at.% of Ar within the mix. The results are discussed in light of the existing models. They can be interesting for introducing a selective and controlled solid-state reaction and towards further studies of ion irradiation stability of amorphous Ni-Ti phase.

  19. Statistical evaluation of the relationships between spatial variability in the organic carbon content in gray forest soils, soil density, concentrations of heavy metals, and topography

    NASA Astrophysics Data System (ADS)

    Shary, P. A.; Pinskii, D. L.

    2013-11-01

    The spatial variability in the organic carbon content (Corg) in the gray forest soils was studied in relation to topography, soil density ( D); and concentrations of Al, Fe, K, Ca, Mg, Mn, Cu, and Zn measured at 47 points in the upper (0-10 cm) and lower (10-20 cm) layers by the X-ray fluorescent method. The study area (48 by 104 m) under meadow vegetation included the break of slope of a river valley with strongly eroded gray forest soils and active development of erosional processes. Methods of geomorphometry were used for the quantitative characterization of topographic conditions. Statistical relationships between the studied characteristics were investigated by multiple regression methods with verification of the models according to specially developed criteria. The obtained statistical relationships were used to develop 3D cartographic models of the Corg and D distribution in the two soil layers. It was shown that the content of Corg in the upper layer increased on south-facing slopes, whereas the content of Corg in the lower layer gained its maximum of southwestern slopes, and the reasons for this distribution were determined. The major characteristics of topography affecting the distribution of Corg in the different soil layers were identified. The Corg content in any soil layer was most tightly correlated with the D values; a less tight correlation was observed between the Corg and Mg contents. The Zn and Cu contents correlated with the Corg in the lower (10-20 cm) layer, whereas the Ca and Fe contents correlated with the Corg in the upper (0-10 cm) layer. The interpretation of the observed regularities involved data on the stability of metal complexes with humic acids under different conditions of the soil acidity; the effect of the erosional processes was also taken into account.

  20. A facile approach towards increasing the nitrogen-content in nitrogen-doped carbon nanotubes via halogenated catalysts

    NASA Astrophysics Data System (ADS)

    Ombaka, L. M.; Ndungu, P. G.; Omondi, B.; McGettrick, J. D.; Davies, M. L.; Nyamori, V. O.

    2016-03-01

    Nitrogen-doped carbon nanotubes (N-CNTs) have been synthesized at 850 °C via a CVD deposition technique by use of three ferrocenyl derivative catalysts, i.e. para-CN, -CF3 and -Cl substituted-phenyl rings. The synthesized catalysts have been characterized by NMR, IR, HR-MS and XRD. The XRD analysis of the para-CF3 catalyst indicates that steric factors influence the X-ray structure of 1,1‧-ferrocenylphenyldiacrylonitriles. Acetonitrile or pyridine was used as carbon and nitrogen sources to yield mixtures of N-CNTs and carbon spheres (CS). The N-CNTs obtained from the para-CF3 catalysts, in pyridine, have the highest nitrogen-doping level, show a helical morphology and are less thermally stable compared with those synthesized by use of the para-CN and -Cl as catalyst. This suggests that fluorine heteroatoms enhance nitrogen-doping in N-CNTs and formation of helical-N-CNTs (H-N-CNTs). The para-CF3 and para-Cl catalysts in acetonitrile yielded iron-filled N-CNTs, indicating that halogens promote encapsulation of iron into the cavity of N-CNT. The use of acetonitrile, as carbon and nitrogen source, with the para-CN and -Cl as catalysts also yielded a mixture of N-CNTs and carbon nanofibres (CNFs), with less abundance of CNFs in the products obtained using para-Cl catalysts. However, para-CF3 catalyst in acetonitrile gave N-CNTs as the only shaped carbon nanomaterials.

  1. Texture, Carbonate Content, and Preliminary Maps of Surficial Sediments of the Flower Garden Banks Area, Northwestern Gulf of Mexico Outer Shelf

    USGS Publications Warehouse

    Scanlon, Kathryn M.; Ackerman, Seth D.; Rozycki, Jill E.

    2003-01-01

    The purpose of this report is to release texture and carbonate content analyses of 107 seafloor sediments collected within and near the East and West Flower Garden Banks areas of the Sanctuary and to show relationships between these data and existing bathymetric data. The sediment data, in conjunction with previously collected geological, geophysical and biological data were used to construct a reconnaissance-scale map of the distribution of seafloor sediment types. This map will be useful for resource managers and can be used, with additional data, as a basis for future habitat mapping.

  2. Transmission electron microscopy studying of structural features of NiTi B2 phase formed under pulsed electron-beam impact

    SciTech Connect

    Meisner, Ludmila L.; Semin, Viktor O.; Gudimova, Ekaterina Y.; Neiman, Alexey A. Lotkov, Alexander I.; Ostapenko, Marina G.; Koval, Nikolai N.; Teresov, Anton D.

    2015-10-27

    By transmission electron microscopy method the evolution of structural-phase states on a depth of close to equiatomic NiTi modified layer has been studied. Modification performed by pulse impact on its surface low-energy high-current electron beam (beam energy density 10 J/sm{sup 2}, 10 pulses, pulse duration 50mks). It is established that during the treatment in the layer thickness of 8–10 μm, the melting of primary B2 phase and contained therein as Ti2Ni phase particles occurs. The result is change in the concentration ratio of titanium and nickel in the direction of increasing titanium content, which was confirmed by X-ray analysis in the form of increased unit cell parameter B2 phase. Analysis of the electron diffraction pattern showed that the modified layer is characterized as a highly distorted structure on the basis of bcc lattice. Lattice distortions are maximal near the surface and extends to a depth of melt. In subjacent layer there is gradual decline lattice distortions is observed.

  3. Comparison of sample digestion techniques for the determination of trace and residual catalyst metal content in single-wall carbon nanotubes by inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Grinberg, Patricia; Sturgeon, Ralph E.; Diehl, Liange de O.; Bizzi, Cezar A.; Flores, Erico M. M.

    2015-03-01

    A single-wall carbon nanotube material produced by laser ablation of renewable biochar in the presence of Ni and Co catalyst was characterized for residual catalyst (Co and Ni) as well as trace metal impurity content (Fe, Mo, Cr, Pb and Hg) by isotope dilution ICP-MS following sample digestion. Several matrix destruction procedures were evaluated, including a multi-step microwave-assisted acid digestion, dry ashing at 450 °C and microwave-induced combustion with oxygen. Results were benchmarked against those derived from neutron activation analysis and also supported by solid sampling continuum source GF-AAS for several of the elements. Although laborious to execute, the multi-step microwave-assisted acid digestion proved to be most reliable for recovery of the majority of the analytes, although content of Cr remained biased low for each approach, likely due to its presence as refractory carbide.

  4. [Estimating nonstructural carbon content of tree crown considering its spatial variability: A case study on Juglans mandshurica and Ulmus japonica].

    PubMed

    Cheng, Fang-yan; Wang, Chuan-kuan

    2015-08-01

    Using Juglans mandshurica and Ulmus japonica as test materials, we examined the variability in nonstructural carbohydrates (NSC) concentrations in the branches with different basal diameters with a branch analysis method and explored potential errors in estimating the crown-scale NSC content introduced from various sampling protocols. The results showed that organs significantly influenced the crown NSC concentrations for both species. The mean concentrations of the sum of soluble sugars and starch (TNC) of the leaves, new twigs, old branches, and dead branches were 17.6%, 12.6%, 5.7% and 2.9%, respectively. Most of the NSC concentrations in leaves and new twigs varied insignificantly with basal diameter, age, length and height of the branch. However, the NSC concentration in old branches increased significantly with decreasing the basal diameter, age and length of the branch, and with increasing the relative height of the branch. Among the branch traits, basal diameter was the best predictor for the NSC concentration of the old branch (the R2 between 0.87 and 0.95). The mean TNC contents of leaves, new branches, and old branches for the two species accounted for 28%, 2% and 70% of the crown TNC content, respectively. Considering the effect of the spatial variability in the estimation of NSC content, we recommend the sampling protocol that applies the NSC concentration of new twigs and old branches with a diameter of 3 cm to up-scale the crown NSC content as a simple and practical method.

  5. Simple fabrication of flexible electrodes with high metal-oxide content: electrospun reduced tungsten oxide/carbon nanofibers for lithium ion battery applications

    NASA Astrophysics Data System (ADS)

    Lee, Jaehyuk; Jo, Changshin; Park, Bangrock; Hwang, Woonbong; Lee, Hyung Ik; Yoon, Songhun; Lee, Jinwoo

    2014-08-01

    A one-step and mass-production synthetic route for a flexible reduced tungsten oxide-carbon composite nanofiber (WOx-C-NF) film is demonstrated via an electrospinning technique. The WOx-C-NF film exhibits unprecedented high content of metal-oxides (~80 wt%) and good flexibility (the tensile strength of the specimen was 6.13 MPa) without the use of flexible support materials like CNTs or graphene. The WOx-C-NF film is directly used as an anode in a lithium ion battery (LIB). Compared with previously reported tungsten oxide electrodes, the WOx-C-NF film exhibits high reversible capacity (481 mA h g-1total electrode), stable cycle, and improved rate performance, without the use of additive carbon, a polymeric binder and a current collector. Moreover, control electrodes fabricated by conventional processes support the positive effects of both the freestanding electrode and metal-oxide embedded carbon 1-D nanofiber structure.A one-step and mass-production synthetic route for a flexible reduced tungsten oxide-carbon composite nanofiber (WOx-C-NF) film is demonstrated via an electrospinning technique. The WOx-C-NF film exhibits unprecedented high content of metal-oxides (~80 wt%) and good flexibility (the tensile strength of the specimen was 6.13 MPa) without the use of flexible support materials like CNTs or graphene. The WOx-C-NF film is directly used as an anode in a lithium ion battery (LIB). Compared with previously reported tungsten oxide electrodes, the WOx-C-NF film exhibits high reversible capacity (481 mA h g-1total electrode), stable cycle, and improved rate performance, without the use of additive carbon, a polymeric binder and a current collector. Moreover, control electrodes fabricated by conventional processes support the positive effects of both the freestanding electrode and metal-oxide embedded carbon 1-D nanofiber structure. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01033g

  6. Effect of Particle Size of Titanium and Nickel on the Synthesis of NiTi by TE-SHS

    NASA Astrophysics Data System (ADS)

    Novák, Pavel; Veselý, Tomáš; Marek, Ivo; Dvořák, Petr; Vojtěch, Vladimír; Salvetr, Pavel; Karlík, Miroslav; Haušild, Petr; Kopeček, Jaromír

    2016-04-01

    In this work, the influence of the particle size of nickel and titanium on the synthesis of NiTi shape memory alloy by self-propagating high-temperature synthesis (SHS) was investigated. It was found that coarse titanium and nickel powders undergo only a limited SHS reaction. On the other hand, too fine powders support the low-temperature diffusional formation of NiTi intermetallics at 773 K to 1073 K (500 °C to 800 °C) which could then suppress the SHS reaction. The optimum powder fraction of both nickel and titanium to achieve the most intensive SHS reaction is 25 to 45 µm. The influence of the particle size of both nickel and titanium on the reaction mechanism is discussed in terms of the microstructure evolution, phase, and chemical composition changes and thermal effects determined by differential thermal analysis.

  7. Determination of Ni Release in NiTi SMA with Surface Modification by Nitrogen Plasma Immersion Ion Implantation

    NASA Astrophysics Data System (ADS)

    de Camargo, Eliene Nogueira; Oliveira Lobo, Anderson; Silva, Maria Margareth Da; Ueda, Mario; Garcia, Edivaldo Egea; Pichon, Luc; Reuther, Helfried; Otubo, Jorge

    2011-07-01

    NiTi SMA is a promising material in the biomedical area due to its mechanical properties and biocompatibility. However, the nickel in the alloy may cause allergic and toxic reactions and thus limiting its applications. It was evaluated the influence of surface modification in NiTi SMA by nitrogen plasma immersion ion implantation (varying temperatures, and exposure time as follows: <250 °C/2 h, 290 °C/2 h, and 560 °C/1 h) in the amount of nickel released using immersion test in simulated body fluid. The depth of the nitrogen implanted layer increased as the implantation temperature increased resulting in the decrease of nickel release. The sample implanted in high implantation temperature presented 35% of nickel release reduction compared to reference sample.

  8. Poly(styrenesulfonate)-Modified Ni-Ti Layered Double Hydroxide Film: A Smart Drug-Eluting Platform.

    PubMed

    Ge, Naijian; Wang, Donghui; Peng, Feng; Li, Jinhua; Qiao, Yuqin; Liu, Xuanyong

    2016-09-21

    Drug-eluting stents (DESs) are widely used in the palliative treatment of many kinds of cancers. However, the covered polymers used in DESs are usually associated with stent migration and acute cholecystitis. Therefore, developing noncovered drug-loading layers on metal stents is of great importance. In this work, Ni-Ti layered double hydroxide (Ni-Ti LDH) films were prepared on the surface of nitinol via hydrothermal treatment, and the LDH films were further modified by poly(styrenesulfonate) (PSS). The anticancer drug doxorubicin could be effectively loaded onto the modified films, and drug release could be smartly controlled by the pH. Besides, the drug absorption amounts of cancer cells cultured on the films could be effectively improved. These results indicate that the PSS-modified LDH film may become a promising drug-loading platform that can be used in the design of DESs. PMID:27579782

  9. Influence of Soft Drinks with Low pH on Different Ni-Ti Orthodontic Archwire Surface Patterns

    NASA Astrophysics Data System (ADS)

    Abalos, C.; Paul, A.; Mendoza, A.; Solano, E.; Palazon, C.; Gil, F. J.

    2013-03-01

    The aim of this study was to determine the influence of soft drinks on the surface of Ni-Ti archwires and their corrosion behavior. Archwires with different patterns (smooth, scratch, dimple, and crack) were selected and characterized by scanning electron microscopy and laser confocal microscopy. Immersion tests were performed in artificial saliva (pH 6.7) with a soft drink with a pH of 2.5 for 28 days. The results showed an increase in the surface defects and/or roughness of the dimple, crack and scratch patterns with the immersion times, and a decrease in corrosion resistance. A relationship between the surface pattern and the extent of the corrosion in Ni-Ti archwires with soft drinks at low pH has been demonstrated. Pattern should be taken into account in future studies, and manufacturing processes that produce surface defects (especially cracks) should be avoided.

  10. Poly(styrenesulfonate)-Modified Ni-Ti Layered Double Hydroxide Film: A Smart Drug-Eluting Platform.

    PubMed

    Ge, Naijian; Wang, Donghui; Peng, Feng; Li, Jinhua; Qiao, Yuqin; Liu, Xuanyong

    2016-09-21

    Drug-eluting stents (DESs) are widely used in the palliative treatment of many kinds of cancers. However, the covered polymers used in DESs are usually associated with stent migration and acute cholecystitis. Therefore, developing noncovered drug-loading layers on metal stents is of great importance. In this work, Ni-Ti layered double hydroxide (Ni-Ti LDH) films were prepared on the surface of nitinol via hydrothermal treatment, and the LDH films were further modified by poly(styrenesulfonate) (PSS). The anticancer drug doxorubicin could be effectively loaded onto the modified films, and drug release could be smartly controlled by the pH. Besides, the drug absorption amounts of cancer cells cultured on the films could be effectively improved. These results indicate that the PSS-modified LDH film may become a promising drug-loading platform that can be used in the design of DESs.

  11. Surface amorphization of NiTi alloy induced by Ultrasonic Nanocrystal Surface Modification for improved mechanical properties.

    PubMed

    Ye, Chang; Zhou, Xianfeng; Telang, Abhishek; Gao, Hongyu; Ren, Zhencheng; Qin, Haifeng; Suslov, Sergey; Gill, Amrinder S; Mannava, S R; Qian, Dong; Doll, Gary L; Martini, Ashlie; Sahai, Nita; Vasudevan, Vijay K

    2016-01-01

    We report herein the effects of Ultrasonic Nano-crystal Surface Modification (UNSM), a severe surface plastic deformation process, on the microstructure, mechanical (hardness, wear), wettability and biocompatibility properties of NiTi shape memory alloy. Complete surface amorphization of NiTi was achieved by this process, which was confirmed by X-ray diffraction and high-resolution transmission electron microscopy. The wear resistance of the samples after UNSM processing was significantly improved compared with the non-processed samples due to increased surface hardness of the alloy by this process. In addition, cell culture study demonstrated that the biocompatibility of the samples after UNSM processing has not been compromised compared to the non-processed sample. The combination of high wear resistance and good biocompatibility makes UNSM an appealing process for treating alloy-based biomedical devices.

  12. Rapid Laser Induced Crystallization of Amorphous NiTi Films Observed by Nanosecond Dynamic Transmission Electron Microscopy (DTEM)

    SciTech Connect

    LaGrange, T; Campbell, G H; Browning, N D; Reed, B W; Grummon, D S

    2010-03-01

    The crystallization processes of the as-deposited, amorphous NiTi thin films have been studied in detail using techniques such as differential scanning calorimetry and, in-situ TEM. The kinetic data have been analyzed in terms of Johnson-Mehl-Avrami-Kolomogrov (JMAK) semi-empirical formula. The kinetic parameters determined from this analysis have been useful in defining process control parameters for tailoring microstructural features and shape memory properties. Due to the commercial push to shrink thin film-based devices, unique processing techniques have been developed using laser-based annealing to spatially control the microstructure evolution down to sub-micron levels. Nanosecond, pulse laser annealing is particularly attractive since it limits the amount of peripheral heating and unwanted microstructural changes to underlying or surrounding material. However, crystallization under pulsed laser irradiation can differ significantly from conventional thermal annealing, e.g., slow heating in a furnace. This is especially true for amorphous NiTi materials and relevant for shape memory thin film based microelectromechanical systems (MEMS) applications. There is little to no data on the crystallization kinetics of NiTi under pulsed laser irradiation, primarily due to the high crystallization rates intrinsic to high temperature annealing and the spatial and temporal resolution limits of standard techniques. However, with the high time and spatial resolution capabilities of the dynamic transmission electron microscope (DTEM) constructed at Lawrence Livermore National Laboratory, the rapid nucleation events occurring from pulsed laser irradiation can be directly observed and nucleation rates can be quantified. This paper briefly explains the DTEM approach and how it used to investigate the pulsed laser induced crystallization processes in NiTi and to determine kinetic parameters.

  13. Surface structure and corrosion resistance of short-time heat-treated NiTi shape memory alloy

    NASA Astrophysics Data System (ADS)

    Vojtěch, D.; Voděrová, M.; Fojt, J.; Novák, P.; Kubásek, T.

    2010-12-01

    NiTi alloys are attractive materials that are used for medicine, however, Ni-release may cause allergic reactions in an organism. The Ni-release rate is strongly affected by the surface state of the NiTi alloy that is mainly determined by its processing route. In this study, a NiTi shape memory alloy (50.9 at.% Ni) was heat-treated by several regimes simulating the shape setting procedure, the last step in the manufacture of implants. Heating temperatures were between 500 and 550 °C and durations from 5 to 10 min. Heat treatments were performed in air at normal and low pressure and in a salt bath. The purpose of the treatments was to obtain and compare different surface states of the Ni-Ti alloy. The surface state and chemistry of heat-treated samples were investigated by electron microscopy, X-ray photoelectron spectroscopy and Raman spectrometry. The amount of nickel released into a model physiological solution of pH 2 and into concentrated HCl was taken as a measure of the corrosion rate. It was found that the heat treatments produced surface TiO 2 layers measuring 15-50 nm in thickness that were depleted in nickel. The sample covered by the 15-nm thick oxide that was treated at 500 °C/5 min in a low pressure air showed the best corrosion performance in terms of Ni-release. As the oxide thickness increased, due to either temperature or oxygen activity change, Ni-release into the physiological solution accelerated. This finding is discussed in relation to the internal structure of the oxide layers.

  14. The super-elastic property of the Japanese NiTi alloy wire for use in orthodontics.

    PubMed

    Miura, F; Mogi, M; Ohura, Y; Hamanaka, H

    1986-07-01

    A new Japanese nickel-titanium (NiTi) alloy wire was developed by the Furukawa Electric Co., Ltd. of Japan. This wire was subjected to uniaxial tensile testing and a specially designed three-point bending test to determine the wire stiffness, and to evaluate spring-back, shape memory, and super-elasticity. The Japanese NiTi wire exhibited an unusual property termed "super-elasticity," which no other orthodontic wire has shown. This phenomenon was researched thoroughly. The wire delivered a constant force over an extended portion of the deactivation range. Among all the wires compared, Japanese NiTi alloy wire was the least likely to undergo permanent deformation during activation. The new alloy exhibited a specific stress-strain curve unlike those of the other tested materials. Stress remained nearly constant despite the strain change within a specific range. This unique feature is the manifestation of so-called super-elasticity. Heat treatment enabled the load magnitude at which super-elasticity is reflected to be influenced and controlled by both temperature and time. A unique and useful process was also developed so that an arch wire delivering various magnitudes of force for a given activation could be fabricated from the wire of the same diameter. The clinical application of wires of this new alloy should be more likely to generate a physiologic tooth movement because of the relatively constant force delivered for a long period of time during the deactivation of the wire. Japanese NiTi alloy should be considered an important material addition to clinical orthodontic metallurgy. PMID:3460342

  15. Laser welding of NiTi shape memory alloy wires and tubes for multi-functional design applications

    NASA Astrophysics Data System (ADS)

    Zeng, Zhi; Yang, Mao; Oliveira, João Pedro; Song, Di; Peng, Bei

    2016-08-01

    Welding and joining of NiTi shape memory alloys is essential for their integration into an increasing variety of applications. Almost all manufacturers and a significant number of researchers focus their investigation on welding NiTi, which can present both pseudoelasticity (PE) and shape memory effect. Integration of these materials would provide increased flexibility in terms of smart design, in particular for multi-functional systems. The current work investigates the mechanical, physical and phase transformation properties of similar (base materials (BMs) with the same composition) and dissimilar (BMs with different compositions) NiTi welded shape memory wires. The similar and dissimilar welded joints were successfully achieved by laser welding, which can reach up to 88.4% and 67.5% of the wire BM ductility. The joint break force of the similar and dissimilar joints were of 77.2% and 71.4% of the wire BM, respectively. Moreover, laser welding was found to effectively preserve the PE on the similar welded structures. The residual plastic strain variation of the dissimilar welded specimens at different temperatures during the cycling test may be helpful for design of multi-functional or flexible monolithic structures.

  16. Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding

    NASA Astrophysics Data System (ADS)

    Czarnowska, Elżbieta; Borowski, Tomasz; Sowińska, Agnieszka; Lelątko, Józef; Oleksiak, Justyna; Kamiński, Janusz; Tarnowski, Michał; Wierzchoń, Tadeusz

    2015-04-01

    NiTi shape memory alloys are used for bone and cardiological implants. However, on account of the metallosis effect, i.e. the release of the alloy elements into surrounding tissues, they are subjected to various surface treatment processes in order to improve their corrosion resistance and biocompatibility without influencing the required shape memory properties. In this paper, the microstructure, topography and morphology of TiN surface layer on NiTi alloy, and corrosion resistance, both before and after nitriding in low-temperature plasma at 290 °C, are presented. Examinations with the use of the potentiodynamic and electrochemical impedance spectroscopy methods were carried out and show an increase of corrosion resistance in Ringer's solution after glow-discharge nitriding. This surface titanium nitride layer also improved the adhesion of platelets and the proliferation of osteoblasts, which was investigated in in vitro experiments with human cells. Experimental data revealed that nitriding NiTi shape memory alloy under low-temperature plasma improves its properties for bone implant applications.

  17. Reliability performance of titanium sputter coated Ni-Ti arch wires: mechanical performance and nickel release evaluation.

    PubMed

    Anuradha, P; Varma, N K Sapna; Balakrishnan, Avinash

    2015-01-01

    The present research was aimed at developing surface coatings on NiTi archwires capable of protection against nickel release and to investigate the stability, mechanical performance and prevention of nickel release of titanium sputter coated NiTi arch wires. Coated and uncoated specimens immersed in artificial saliva were subjected to critical evaluation of parameters such as surface analysis, mechanical testing, element release, friction coefficient and adhesion of the coating. Titanium coatings exhibited high reliability on exposure even for a prolonged period of 30 days in artificial saliva. The coatings were found to be relatively stable on linear scratch test with reduced frictional coefficient compared to uncoated samples. Titanium sputtering adhered well with the Ni-Ti substrates at the molecular level, this was further confirmed by Inductive coupled plasma emission spectroscopy (ICPE) analysis which showed no dissolution of nickel in the artificial saliva. Titanium sputter coatings seem to be promising for nickel sensitive patients. The study confirmed the superior nature of the coating, evident as reduced surface roughness, friction coefficient, good adhesion and minimal hardness and elastic modulus variations in artificial saliva over a given time period.

  18. Linking simulations and experiments for the multiscale tracking of thermally induced martensitic phase transformation in NiTi SMA

    NASA Astrophysics Data System (ADS)

    Gur, Sourav; Frantziskonis, George N.

    2016-10-01

    Martensitic phase transformation in NiTi shape memory alloys (SMA) occurs over a hierarchy of spatial scales, as evidenced from observed multiscale patterns of the martensitic phase fraction, which depend on the material microstructure and on the size of the SMA specimen. This paper presents a methodology for the multiscale tracking of the thermally induced martensitic phase transformation process in NiTi SMA. Fine scale stochastic phase field simulations are coupled to macroscale experimental measurements through the compound wavelet matrix method (CWM). A novel process for obtaining CWM fine scale wavelet coefficients is used that enhances the effectiveness of the method in transferring uncertainties from fine to coarse scales, and also ensures the preservation of spatial correlations in the phase fraction pattern. Size effects, well-documented in the literature, play an important role in designing the multiscale tracking methodology. Molecular dynamics (MD) simulations are employed to verify the phase field simulations in terms of different statistical measures and to demonstrate size effects at the nanometer scale. The effects of thermally induced martensite phase fraction uncertainties on the constitutive response of NiTi SMA is demonstrated.

  19. Highly Porous NiTi with Isotropic Pore Morphology Fabricated by Self-Propagated High-Temperature Synthesis

    NASA Astrophysics Data System (ADS)

    Hosseini, S. A.; Alizadeh, M.; Ghasemi, A.; Meshkot, M. A.

    2013-02-01

    Highly porous NiTi with isotropic pore morphology has been successfully produced by self-propagating high-temperature synthesis of elemental Ni/Ti metallic powders. The effects of adding urea and NaCl as temporary pore fillers were investigated on pore morphology, microstructure, chemical composition, and the phase transformation temperatures of specimens. These parameters were studied by optical microscopy, scanning electron microscopy, x-ray diffraction, and differential scanning calorimetry (DSC). Highly porous specimens were obtained with up to 83% total porosity and pore sizes between 300 and 500 μm in diameter. Results show pore characteristics were improved from anisotropic to isotropic and pore morphology was changed from channel-like to irregular by adding pore filler powders. Furthermore, the highly porous specimens produced when using urea as a space holder, were of more uniform composition in comparison to NaCl. DSC results showed that a two-step martensitic phase transformation takes place during the cooling cycles and the austenite finish temperature ( A f) is close to human body temperature. Compression test results reveal that the compressive strength of highly porous NiTi is about 155 MPa and recoverable strain about 6% in superelasticity regime.

  20. Self-centering and damping capabilities of a tension-compression device equipped with superelastic NiTi wires

    NASA Astrophysics Data System (ADS)

    Soul, H.; Yawny, A.

    2015-07-01

    The hysteretic damping capacity and high recoverable strains characterizing the superelastic response of shape memory alloys (SMA) make these materials attractive for protection systems of structures subjected to dynamic loads. A successful implementation however is conditioned by functional fatigue exhibited by the SMA when subjected to cyclic loading. The residual deformation upon cycling and the efficiency in material usage are the two most restrictive issues in this sense. In this paper, a device equipped with superelastic NiTi SMA wires and capable of supporting external tension compression loads with optimized properties is presented. It is shown how the introduction of the wires’ pre-straining allows for the absorption of deleterious residual deformation without affecting the self-centering capabilities upon unloading, in contrast with what occurs for pre-strained tendons. These features were experimentally verified in an in-scale prototype composed of two 1.2 mm diameter superelastic NiTi SMA wires. In order to numerically assess the dynamic response of a simple structure subjected to seismic excitations, a multilinear superelasticity model for the NiTi wires was developed.

  1. A comparison of methods for the training of NiTi two-way shape memory alloy

    NASA Astrophysics Data System (ADS)

    Luo, H. Y.; Abel, E. W.

    2007-12-01

    The creation of an effective two-way shape memory alloy (TWSMA) requires appropriate heat treatment and optimal training considerations. In particular, the training method used plays a key role. This work investigates different training methods for producing NiTi TWSMA wires with the hot shape of an arc and the cold shape of a straight line. These methods are shape memory cycling, constrained cycling of deformed martensite, pseudoelastic cycling and combined shape memory and pseudoelastic cycling. In order to give a meaningful evaluation of their performance that is relevant to training TWSMA for practical applications, these training methods are assessed in terms of maximum two-way strain, changes in the original hot shape together with the transformation temperatures after the training process, and the effective production of the cold shape. It was found that only the combined shape memory and pseudoelastic cycling provides an effective training method for creating NiTi TWSMA with a non-uniaxial two-way shape change. The undesirable side effects of training are that the NiTi TWSMA wire loses partial memory of the original hot shape and its transformation temperatures shift to lower values. There also exists an optimal number of training cycles, and possibly an optimal training load for obtaining the best cold shape memory and the greatest two-way recoverable strain. These findings give future directions to advance the training technology for TWSMA.

  2. Multiple-Input Data Acquisition System (MIDAS) for Measuring the Carbon Content in Soil Using Inelastic Neutron Scattering

    SciTech Connect

    Warburton, William K.

    2014-01-24

    This report describes work funder under STTR grants Phase I and II and carried out jointly by XIA LLC and Brookhaven National Laboratory (BNL). The project goal was to develop a mobile nuclear activation analysis instrument that could be towed behind a tractor to document soil carbon levels in agricultural lands for carbon credit certification. XIA developed large NaI(Tl) detectors with integrated digital pulse processors controlled over USB 2.0 and delivered 16 of these units to BNL for integration into the prototype instrument, together with the necessary software to calibrate them and collect data. For reasons that are unknown to XIA, the BNL participants never completed the prototype vehicle, performed system integration, or carried out the proposed qualification and field tests, leaving the project incomplete.

  3. Growth of vertically aligned multiwalled carbon nanotubes forests on metal alloy Ni-Nb-N with low content of catalyst

    NASA Astrophysics Data System (ADS)

    Dubkov, S.; Trifonov, A.; Shaman, Yu; Pavlov, A.; Shulyat'ev, A.; Skorik, S.; Kirilenko, E. P.; Rygalin, B.

    2016-08-01

    This research shows the possibility of carbon nanotubes (CNTs) formation on the surface of low nickel (∼ 10 at.%) Ni-Nb-N amorphous metal alloy film by CVD method at 550 °C of the gas mixture based on acetylene. The structure of CNT were studied by transmission and scanning-electron microscopy, energy-dispersive X-ray and the Raman spectroscopy.

  4. Versatile and Biomass Synthesis of Iron-based Nanoparticles Supported on Carbon Matrix with High Iron Content and Tunable Reactivity

    SciTech Connect

    Zhang, Dongmao; Shi, Sheldon Q; Jiang, Dongping; Che, Wen; Gai, Zheng; Howe, Jane Y; More, Karren Leslie; Arockiasamy, Antonyraj

    2012-01-01

    Iron-based nanoparticles supported on carbon (FeNPs{at}C) have enormous potential for environmental applications. Reported is a biomass-based method for FeNP{at}C synthesis that involves pyrolysis of bleached wood fiber pre-mixed with Fe{sub 3}O{sub 4} nanoparticles. This method allows synthesis of iron-based nanoparticles with tunable chemical reactivity by changing the pyrolysis temperature. The FeNP{at}C synthesized at a pyrolysis temperature of 500 C (FeNP{at}C-500) reacts violently (pyrophoric) when exposed to air, while FeNP{at}C prepared at 800 C (FeNP{at}C-800) remains stable in ambient condition for at least 3 months. The FeNPs in FeNP{at}C-800 are mostly below 50 nm in diameter and are surrounded by carbon. The immediate carbon layer (within 5-15 nm radius) on the FeNPs is graphitized. Proof-of-concept environmental applications of FeNPs{at}C-800 were demonstrated by Rhodamine 6G and arsenate (V) removal from water. This biomass-based method provides an effective way for iron-based nanoparticle fabrication and biomass utilization.

  5. B content and Si/C ratios from cultured diatoms (Thalassiosira pseudonana and Thalassiosira weissflogii): Relationship to seawater pH and diatom carbon acquisition

    NASA Astrophysics Data System (ADS)

    Mejía, Luz María; Isensee, Kirsten; Méndez-Vicente, Ana; Pisonero, Jorge; Shimizu, Nobumichi; González, Cristina; Monteleone, Brian; Stoll, Heather

    2013-12-01

    Despite the importance of diatoms in regulating climate and the existence of large opal-containing sediments in key air-ocean exchange areas, most geochemical proxy records are based on carbonates. Among them, Boron (B) content and isotopic composition have been widely used to reconstruct pH from foraminifera and coral fossils. We assessed the possibility of a pH/CO2 seawater concentration control on B content in diatom opal to determine whether or not frustule B concentrations could be used as a pH proxy or to clarify algae physiological responses to acidifying pH. We cultured two well-studied diatom species, Thalassiosira pseudonana and Thalassiosira weissflogii at varying pH conditions and determined Si and C quotas. Frustule B content was measured by both laser-ablation inductively coupled mass spectrometry (LA-ICPMS) and secondary ion mass spectrometry (SIMS/ion probe). For both species, frustules grown at higher pH have higher B contents and higher Si requirements per fixed C. If this trend is representative of diatom silicification in a future more acidic ocean, it could contribute to changes in the efficiency of diatom ballasting and C export, as well as changes in the contribution of diatoms relative to other phytoplankton groups in Si-limited regions. If B enters the cell through the same transporter employed for HCO3- uptake, an increased HCO3- requirement with decreasing CO2 concentrations (higher pH), and higher B(OH)4/HCO3- ratios would explain the observed increase in frustule B content with increasing pH. The mechanism of B transport from the site of uptake to the site of silica deposition is unknown, but may occur via silicon transport vesicles, in which B(OH)4- may be imported for B detoxification and/or as part of a pH regulation strategy either though Na-dependent B(OH)4-/Cl- antiport or B(OH)4-/H+ antiport. B deposition in the silica matrix may occur via substitution of a B(OH)4- for a negatively charged SiO- formed during silicification. With

  6. Acid neutralizing capacity and leachate results for igneous rocks, with associated carbon contents of derived soils, Animas River AML site, Silverton, Colorado

    USGS Publications Warehouse

    Yager, Douglas B.; Stanton, Mark R.; Choate, LaDonna M.; Burchell,

    2009-01-01

    Mine planning efforts have historically overlooked the possible acid neutralizing capacity (ANC) that local igneous rocks can provide to help neutralize acidmine drainage. As a result, limestone has been traditionally hauled to mine sites for use in neutralizing acid drainage. Local igneous rocks, when used as part of mine life-cycle planning and acid mitigation strategy, may reduce the need to transport limestone to mine sites because these rocks can contain acid neutralizing minerals. Igneous hydrothermal events often introduce moderately altered mineral assemblages peripheral to more intensely altered rocks that host metal-bearing veins and ore bodies. These less altered rocks can contain ANC minerals (calcite-chlorite-epidote) and are referred to as a propylitic assemblage. In addition, the carbon contents of soils in areas of new mining or those areas undergoing restoration have been historically unknown. Soil organic carbon is an important constituent to characterize as a soil recovery benchmark that can be referred to during mine cycle planning and restoration.
    This study addresses the mineralogy, ANC, and leachate chemistry of propylitic volcanic rocks that host polymetallic mineralization in the Animas River watershed near the historical Silverton, Colorado, mining area. Acid titration tests on volcanic rocks containing calcite (2 – 20 wt %) and chlorite (6 – 25 wt %), have ANC ranging from 4 – 146 kg/ton CaCO3 equivalence. Results from a 6-month duration, kinetic reaction vessel test containing layered pyritic mine waste and underlying ANC volcanic rock (saturated with deionized water) indicate that acid generating mine waste (pH 2.4) has not overwhelmed the ANC of propylitic volcanic rocks (pH 5.8). Sequential leachate laboratory experiments evaluated the concentration of metals liberated during leaching. Leachate concentrations of Cu-Zn-As-Pb for ANC volcanic rock are one-to-three orders of magnitude lower when compared to leached

  7. The influence of dissolved H2O content in supercritical carbon dioxide to the inclusion complexes formation of ketoprofen/β-cyclodextrin

    NASA Astrophysics Data System (ADS)

    Goenawan, Joshua; Trisanti, P. N.; Sumarno

    2015-12-01

    This work studies the relation between dissolved H2O content in supercritical carbon dioxide (SC-CO2) with the formation of ketoprofen (KP)/β-cyclodextrin(CD) inclusion complexes. The process involves a physical mixture of these two compounds into contact with the supercritical carbon dioxide which had been previously saturated with H2O over a certain duration. The pressure used for saturation process is 130 bar and saturation temperature was ranged between 30 °C to 50 °C. The inclusion process was achieved by keeping it for 2 hours at 160 bar and 200 bar with inclusion temperature of 50 °C. The results enable us to suggest explanations for the inclusion formation. The inclusion complexes can be formed by contacting the dissolved H2O in SC-CO2 to the physical mixture of KP and CD. An increase in the temperature of saturation process resulted in an increase of dissolved H2O content in the supercritical carbon dioxide. The increasing levels of this water soluble resulted an increase in the inclusion complexes that has been formed. The formation of inclusion complexes includes the water molecules enhancing the emptying of the CD cavities and being replaced by KP, towards a more stable energy state. The drug release used for analyzing the dissolution rate of the KP/CD complexes. The results vary from 79,85% to 99,98% after 45 minutes which is above the rate that has been assigned by Farmakope Indonesia at 70% dissolution rate for KP. The use of SC-CO2 offers a new methods for increasing the rate of dissolution of drugs that are hydrophobic such as KP. CO2 used as a supercritical fluid because of its relatively low cost, easily obtainable supercritical conditions, and lack of toxicity. The material samples were characterized by DSC and Spectrophotometer UV-vis technique.

  8. Arabidopsis thaliana ggt1 photorespiratory mutants maintain leaf carbon/nitrogen balance by reducing RuBisCO content and plant growth.

    PubMed

    Dellero, Younès; Lamothe-Sibold, Marlène; Jossier, Mathieu; Hodges, Michael

    2015-09-01

    Metabolic and physiological analyses of glutamate:glyoxylate aminotransferase 1 (GGT1) mutants were performed at the global leaf scale to elucidate the mechanisms involved in their photorespiratory growth phenotype. Air-grown ggt1 mutants showed retarded growth and development, that was not observed at high CO2 (3000 μL L(-1) ). When compared to wild-type (WT) plants, air-grown ggt1 plants exhibited glyoxylate accumulation, global changes in amino acid amounts including a decrease in serine content, lower organic acid levels, and modified ATP/ADP and NADP(+) /NADPH ratios. When compared to WT plants, their net CO2 assimilation rates (An ) were 50% lower and this mirrored decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) contents. High CO2 -grown ggt1 plants transferred to air revealed a rapid decrease of An and photosynthetic electron transfer rate while maintaining a high energetic state. Short-term (a night period and 4 h of light) transferred ggt1 leaves accumulated glyoxylate and exhibited low serine contents, while other amino acid levels were not modified. RuBisCO content, activity and activation state were not altered after a short-term transfer while the ATP/ADP ratio was lowered in ggt1 rosettes. However, plant growth and RuBisCO levels were both reduced in ggt1 leaves after a long-term (12 days) acclimation to air from high CO2 when compared to WT plants. The data are discussed with respect to a reduced photorespiratory carbon recycling in the mutants. It is proposed that the low An limits nitrogen-assimilation, this decreases leaf RuBisCO content until plants attain a new homeostatic state that maintains a constant C/N balance and leads to smaller, slower growing plants. PMID:26216646

  9. Arabidopsis thaliana ggt1 photorespiratory mutants maintain leaf carbon/nitrogen balance by reducing RuBisCO content and plant growth.

    PubMed

    Dellero, Younès; Lamothe-Sibold, Marlène; Jossier, Mathieu; Hodges, Michael

    2015-09-01

    Metabolic and physiological analyses of glutamate:glyoxylate aminotransferase 1 (GGT1) mutants were performed at the global leaf scale to elucidate the mechanisms involved in their photorespiratory growth phenotype. Air-grown ggt1 mutants showed retarded growth and development, that was not observed at high CO2 (3000 μL L(-1) ). When compared to wild-type (WT) plants, air-grown ggt1 plants exhibited glyoxylate accumulation, global changes in amino acid amounts including a decrease in serine content, lower organic acid levels, and modified ATP/ADP and NADP(+) /NADPH ratios. When compared to WT plants, their net CO2 assimilation rates (An ) were 50% lower and this mirrored decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) contents. High CO2 -grown ggt1 plants transferred to air revealed a rapid decrease of An and photosynthetic electron transfer rate while maintaining a high energetic state. Short-term (a night period and 4 h of light) transferred ggt1 leaves accumulated glyoxylate and exhibited low serine contents, while other amino acid levels were not modified. RuBisCO content, activity and activation state were not altered after a short-term transfer while the ATP/ADP ratio was lowered in ggt1 rosettes. However, plant growth and RuBisCO levels were both reduced in ggt1 leaves after a long-term (12 days) acclimation to air from high CO2 when compared to WT plants. The data are discussed with respect to a reduced photorespiratory carbon recycling in the mutants. It is proposed that the low An limits nitrogen-assimilation, this decreases leaf RuBisCO content until plants attain a new homeostatic state that maintains a constant C/N balance and leads to smaller, slower growing plants.

  10. Facile Preparation and Lithium Storage Properties of TiO2 @Graphene Composite Electrodes with Low Carbon Content.

    PubMed

    Guo, Sheng-Qi; Zhen, Meng-Meng; Liu, Lu; Yuan, Zhi-Hao

    2016-08-16

    Over the past decade, TiO2 /graphene composites as electrodes for lithium ion batteries have attracted a great deal of attention for reasons of safety and environmental friendliness. However, most of the TiO2 /graphene electrodes have large graphene content (9-40 %), which is bound to increase the cost of the battery. Logically, reducing the amount of graphene is a necessary part to achieve a green battery. The synthesis of TiO2 nanosheets under solvothermal conditions without additives is now demonstrated. Through mechanical mixing TiO2 nanosheets with different amount of reduced graphene (rGO), a series of TiO2 @graphene composites was prepared with low graphene content (rGO content 1, 2, 3, and 5 wt %). When these composites were evaluated as anodes for lithium ion batteries, it was found that TiO2 +3 wt % rGO manifested excellent cycling stability and a high specific capacity (243.7 mAh g(-1) at 1 C; 1 C=167.5 mA g(-1) ), and demonstrated superior high-rate discharge/charge capability at 20 C. PMID:27339820

  11. Small-angle neutron scattering study of activated carbon cloth and ammonium persulfate-modified activated carbon cloth: Effect of oxygen content

    NASA Astrophysics Data System (ADS)

    Pendleton, Phillip; Chen, Lin

    2006-11-01

    Small-angle neutron scattering (SANS) patterns of as-received, oxidized, and thermally reduced FM1/250 activated carbon cloth (ACC) samples are compared to determine the effects of surface chemistry on scattering. Porosity analyses show minimal effect on pore size distribution from oxidation, but an increase in micropore volume on heat treatment. SANS suggests an increase in localized order within the treated samples when compared with graphite cloth patterns. The ACC exhibits Porod scattering at q-ranges<0.3 nm -1; the graphite cloth exhibits the same at q-ranges>1.0 nm -1. A cylindrical model reproduces the scattering patterns in the micropore equivalent dimensions, q>0.5 nm -1.

  12. Lipid biomarkers for anaerobic oxidation of methane and sulphate reduction in cold seep sediments of Nyegga pockmarks (Norwegian margin): discrepancies in contents and carbon isotope signatures

    NASA Astrophysics Data System (ADS)

    Chevalier, Nicolas; Bouloubassi, Ioanna; Stadnitskaia, Alina; Taphanel, Marie-Hélène; Sinninghe Damsté, Jaap S.

    2014-06-01

    Distributions and carbon isotopic compositions of microbial lipid biomarkers were investigated in sediment cores from the G11 and G12 pockmarks in the Nyegga sector of the Storegga Slide on the mid-Norwegian margin to explore differences in depth zonation, type and carbon assimilation mode of anaerobic methane-oxidizing archaea (ANMEs) and associated sulphate-reducing bacteria responsible for anaerobic oxidation of methane (AOM) in these cold seep environments. While the G11 site is characterised by black reduced sediments colonized by gastropods and Siboglinidae tubeworms, the G12 site has black reduced sediments devoid of fauna but surrounded by a peripheral occurrence of gastropods and white filamentous microbial mats. At both sites, bulk sediments contained abundant archaeal and bacterial lipid biomarkers substantially depleted in 13C, consisting mainly of isoprenoidal hydrocarbons and dialkyl glycerol diethers, fatty acids and non-isoprenoidal monoalkylglycerol ethers. At the G11 site, down-core profiles revealed that lipid biomarkers were in maximum abundance from 10 cm depth to the core bottom at 16 cm depth, associated with δ13C values of -57 to -136‰. At the G12 site, by contrast, lipid biomarkers were in high abundance in the upper 5 cm sediment layer, associated with δ13C values of -43 to -133‰. This suggests that, as expected from the benthic fauna characteristics of the sites, AOM takes place mainly at depth in the G11 pockmark but just below the seafloor in the G12 pockmark. These patterns can be explained largely by variable fluid flow rates. Furthermore, at both sites, a dominance of ANME-2 archaea accompanied by their bacterial partners is inferred based on lipid biomarker distributions and carbon isotope signatures, which is in agreement with recently published DNA analyses for the G11 pockmark. However, the present data reveal high discrepancies in the contents and δ13C values for both archaeal and bacterial lipid profiles, implying the

  13. Effects of Propylene Carbonate Content in CsPF₆-Containing Electrolytes on the Enhanced Performances of Graphite Electrode for Lithium-Ion Batteries.

    PubMed

    Zheng, Jianming; Yan, Pengfei; Cao, Ruiguo; Xiang, Hongfa; Engelhard, Mark H; Polzin, Bryant J; Wang, Chongmin; Zhang, Ji-Guang; Xu, Wu

    2016-03-01

    The effects of propylene carbonate (PC) content in CsPF6-containing electrolytes on the performances of graphite electrode in lithium half cells and in graphite∥LiNi0.80Co0.15Al0.05O2 (NCA) full cells are investigated. It is found that the performance of graphite electrode is significantly affected by PC content in the CsPF6-containing electrolytes. An optimal PC content of 20% by weight in the solvent mixtures is identified. The enhanced electrochemical performance of graphite electrode can be attributed to the synergistic effects of the PC solvent and the Cs(+) additive. The synergistic effects of Cs(+) additive and appropriate amount of PC enable the formation of a robust, ultrathin, and compact solid electrolyte interphase (SEI) layer on the surface of graphite electrode, which is only permeable for desolvated Li(+) ions and allows fast Li(+) ion transport through it. Therefore, this SEI layer effectively suppresses the PC cointercalation and largely alleviates the Li dendrite formation on graphite electrode during lithiation even at relatively high current densities. The presence of low-melting-point PC solvent improves the sustainable operation of graphite∥NCA full cells under a wide temperature range. The fundamental findings also shed light on the importance of manipulating/maintaining the electrode/electrolyte interphasial stability in various energy-storage devices.

  14. The impact of enhanced atmospheric carbon dioxide on yield, proximate composition, elemental concentration, fatty acid and vitamin C contents of tomato (Lycopersicon esculentum).

    PubMed

    Khan, Ikhtiar; Azam, Andaleeb; Mahmood, Abid

    2013-01-01

    The global average temperature has witnessed a steady increase during the second half of the twentieth century and the trend is continuing. Carbon dioxide, a major green house gas is piling up in the atmosphere and besides causing global warming, is expected to alter the physico-chemical composition of plants. The objective of this work was to evaluate the hypothesis that increased CO(2) in the air is causing undesirable changes in the nutritional composition of tomato fruits. Two varieties of tomato (Lycopersicon esculentum) were grown in ambient (400 μmol mol(-1)) and elevated (1,000 μmol mol(-1)) concentration of CO(2) under controlled conditions. The fruits were harvested at premature and fully matured stages and analyzed for yield, proximate composition, elemental concentration, fatty acid, and vitamin C contents. The amount of carbohydrates increased significantly under the enhanced CO(2) conditions. The amount of crude protein and vitamin C, two important nutritional parameters, decreased substantially. Fatty acid content showed a mild decrease with a slight increase in crude fiber. Understandably, the effect of enhanced atmospheric CO(2) was more pronounced at the fully matured stage. Mineral contents of the fruit samples changed in an irregular fashion. Tomato fruit has been traditionally a source of vitamin C, under the experimental conditions, a negative impact of enhanced CO(2) on this source of vitamin C was observed. The nutritional quality of both varieties of tomato has altered under the CO(2) enriched atmosphere. PMID:22382378

  15. Carbon dioxide adsorption on micro-mesoporous composite materials of ZSM-12/MCM-48 type: The role of the contents of zeolite and functionalized amine

    SciTech Connect

    Santos, S.C.G.

    2015-10-15

    Highlights: • Synthesis of the micro-mesoporous composite materials of ZSM-12/MCM-48 type. • Application of these adsorbents in the carbon dioxide adsorption. • Effects of the contents of zeolite and amino group in the material surface on the CO{sub 2} capture efficiency. - Abstract: In this study ZSM-12/MCM-48 adsorbents have been synthesized at three ZSM-12 content, and also were functionalizated with amine groups by grafting. All the adsorbents synthesized were evaluated for CO{sub 2} capture. The X-ray diffraction analysis of the ZSM-12/MCM-48 composite showed the main characteristic peaks of ZSM-12 and MCM-48, and after the functionalization, the structure of MCM-48 on the composite impregnated was affected due amine presence. For the composites without amine, the ZSM-12 content was the factor determining in the adsorption capacity of CO{sub 2} and for the composites with amine the amount of amine was that influenced in the adsorption capacity.

  16. [Effects of grape seed addition in swine manure-wheat straw composting on the compost microbial community and carbon and nitrogen contents].

    PubMed

    Huang, Yi-Mei; Liu, Xue-Ling; Jiang, Ji-Shao; Huang, Hua; Liu, Dong

    2012-08-01

    Taking substrates swine manure and wheat straw (fresh mass ratio 10.5:1) as the control (PMW), a composting experiment was conducted in a self-made aerated static composting bin to study the effects of adding 8% grape seed (treatment PMW + G) on the succession of microbial community and the transformation of carbon and nitrogen in the substrates during the composting. Seven samples were collected from each treatment, according to the temperature of the compost during the 30 d composting period. The microbial population and physiological groups were determined, and the NH4(+)-N, NO3(-)-N, organic N, and organic C concentrations in the compost were measured. Grape seed addition induced a slight increase of bacterial count and a significant increase of actinomycetes count, but decreased the fungal count significantly. Grape seed addition also decreased the ratio of bacteria to actinomycetes and the counts of ammonifiers and denitrifiers, but increased the counts of nitrifiers, N-fixing bacteria, and cellulose-decomposing microorganisms. The contents of NH4(+)-N and organic C decreased, while that of NO3(-)-N increased obviously. The NO3(-)-N content in the compost was positively correlated with the actinomycetes count. During composting, the compost temperature in treatment PMW + G increased more rapidly, and remained steady in thermophilic phase, while the water content changed little, which provided a stable and higher population of actinomycetes and nitrifiers in thermophilic phase, being beneficial to the increase of compost nitrate N.

  17. The impact of enhanced atmospheric carbon dioxide on yield, proximate composition, elemental concentration, fatty acid and vitamin C contents of tomato (Lycopersicon esculentum).

    PubMed

    Khan, Ikhtiar; Azam, Andaleeb; Mahmood, Abid

    2013-01-01

    The global average temperature has witnessed a steady increase during the second half of the twentieth century and the trend is continuing. Carbon dioxide, a major green house gas is piling up in the atmosphere and besides causing global warming, is expected to alter the physico-chemical composition of plants. The objective of this work was to evaluate the hypothesis that increased CO(2) in the air is causing undesirable changes in the nutritional composition of tomato fruits. Two varieties of tomato (Lycopersicon esculentum) were grown in ambient (400 μmol mol(-1)) and elevated (1,000 μmol mol(-1)) concentration of CO(2) under controlled conditions. The fruits were harvested at premature and fully matured stages and analyzed for yield, proximate composition, elemental concentration, fatty acid, and vitamin C contents. The amount of carbohydrates increased significantly under the enhanced CO(2) conditions. The amount of crude protein and vitamin C, two important nutritional parameters, decreased substantially. Fatty acid content showed a mild decrease with a slight increase in crude fiber. Understandably, the effect of enhanced atmospheric CO(2) was more pronounced at the fully matured stage. Mineral contents of the fruit samples changed in an irregular fashion. Tomato fruit has been traditionally a source of vitamin C, under the experimental conditions, a negative impact of enhanced CO(2) on this source of vitamin C was observed. The nutritional quality of both varieties of tomato has altered under the CO(2) enriched atmosphere.

  18. Evaluation of Mechanical and Physical Properties of Clinically Used and Recycled Superelastic NiTi Wires

    PubMed Central

    Bavikati, Venkata Naidu; Mandava, Prasad; Killamsetty, Sai Sandeep; Nettam, Venkatesh; Karnati, Praveen Kumar Reddy

    2016-01-01

    Introduction The initial leveling and aligning phase has been simplified with the introduction of superelastic nickel-titanium archwires. The relatively high cost of these wires has prompted some of the clinicians to reuse them after sterilization. The quantitative changes in the surface properties of superelastic ‘NiTi’ wires after clinical application and recycling by autoclave method have not been established in earlier studies. Aim To quantify the changes in mechanical and physical properties of four different commercially available superelastic nitinol (NiTi) archwires after clinical usage and recycling. Materials and Methods The superelastic ‘NiTi archwires obtained from four different manufacturers: Group I-GAC (McMinnville, USA); Group II- 3M Company (California, USA); Group III- G&H Company(Franklin, USA) and Group IV- American Orthodontics (AO) (Sheboygan, USA) were selected for the study. Each of the four groups comprised of 20 samples of wire with 10 of them selected randomly as control and remaining 10 as test specimen in each group. The experimental archwires were placed on selected patients for a period of three months followed by Standard Autoclave sterilization at 121°C and 15 to 20 psi pressure for 20 minutes and were retrieved. The tensile strength was evaluated by Instron-Universal Testing Machine. The quantification of changes in surface roughness was investigated by grid method using Scanning Electron Microscope (SEM). The Control Wires (C) were evaluated at initial time “T1” where as the Experimental sample of wires (T) were subjected to testing at an initial time ‘T1’ and after clinical usage and sterilization at ‘T2’ Statistical Analysis Paired t-test was used for intra-group comparison and one way ANOVA and Post Hoc Tukey tests were used for inter-group comparison. Results There was significant decrease in tensile strength (p = 0.0015 to 0.001) and surface roughness (p< 0.001) between control and experimental arch wires

  19. Evaluation of Mechanical and Physical Properties of Clinically Used and Recycled Superelastic NiTi Wires

    PubMed Central

    Bavikati, Venkata Naidu; Mandava, Prasad; Killamsetty, Sai Sandeep; Nettam, Venkatesh; Karnati, Praveen Kumar Reddy

    2016-01-01

    Introduction The initial leveling and aligning phase has been simplified with the introduction of superelastic nickel-titanium archwires. The relatively high cost of these wires has prompted some of the clinicians to reuse them after sterilization. The quantitative changes in the surface properties of superelastic ‘NiTi’ wires after clinical application and recycling by autoclave method have not been established in earlier studies. Aim To quantify the changes in mechanical and physical properties of four different commercially available superelastic nitinol (NiTi) archwires after clinical usage and recycling. Materials and Methods The superelastic ‘NiTi archwires obtained from four different manufacturers: Group I-GAC (McMinnville, USA); Group II- 3M Company (California, USA); Group III- G&H Company(Franklin, USA) and Group IV- American Orthodontics (AO) (Sheboygan, USA) were selected for the study. Each of the four groups comprised of 20 samples of wire with 10 of them selected randomly as control and remaining 10 as test specimen in each group. The experimental archwires were placed on selected patients for a period of three months followed by Standard Autoclave sterilization at 121°C and 15 to 20 psi pressure for 20 minutes and were retrieved. The tensile strength was evaluated by Instron-Universal Testing Machine. The quantification of changes in surface roughness was investigated by grid method using Scanning Electron Microscope (SEM). The Control Wires (C) were evaluated at initial time “T1” where as the Experimental sample of wires (T) were subjected to testing at an initial time ‘T1’ and after clinical usage and sterilization at ‘T2’ Statistical Analysis Paired t-test was used for intra-group comparison and one way ANOVA and Post Hoc Tukey tests were used for inter-group comparison. Results There was significant decrease in tensile strength (p = 0.0015 to 0.001) and surface roughness (p< 0.001) between control and experimental arch wires

  20. Comparison of indoor/outdoor carbon content and time resolved PM concentrations for gas and biomass cooking fuels in Nogales, Sonora, Mexico

    NASA Astrophysics Data System (ADS)

    Holmes, Heather A.; Pardyjak, Eric R.; Speckart, Scott O.; Alexander, Daniel

    2011-12-01

    A case study designed to investigate indoor and outdoor air quality in naturally ventilated homes near the US-Mexico border was conducted in Nogales, Sonora, Mexico from 14-30 March 2009. To better understand resident's actual exposure to various sizes of particulate matter ( PM), we compare measured concentrations in homes using different household stove cooking fuels (gas versus biomass) and investigate the spatial distribution of outdoor PM. Data from two home locations, one with a gas stove and one with both biomass and gas stoves are evaluated. In each home, continuous PM concentrations were sampled over a range of particle sizes. Indoor and outdoor concentration measurements were facilitated using a valve switching system. PM2.5 was also sampled on quartz filters located inside and outside of the two homes for carbon analysis. This paper will present a subset of the field data to compare time resolved indoor PM concentrations and carbon content for the two homes; specifically, comparing cooking versus non-cooking time periods. Results indicate that indoor elemental carbon concentrations are dominated by indoor sources during biomass burning, and outdoor sources at all other times. The data indicate that the influence of indoor sources on organic carbon concentrations increases during both gas and biomass stove use; this information is correlated to continuous indoor PM concentrations and home activities. The mean 24 h indoor PM10 concentration was 408 μg m -3 for the gas stove home and 648 μg m -3 for the home with biomass and gas stoves, while the outdoor concentrations were 609 μg m -3 and 381 μg m -3, respectively. The average 24 h PM10 Indoor/Outdoor ratio was 0.71 for the gas stove home and 1.79 for the home with both gas and biomass stoves. These ratios should be interpreted with caution as they appear to underestimate the indoor source contribution due to high outdoor PM levels.

  1. The oxygen content of ocean bottom waters, the burial efficiency of organic carbon, and the regulation of atmospheric oxygen

    NASA Technical Reports Server (NTRS)

    Betts, J. N.; Holland, H. D.

    1991-01-01

    Data for the burial efficiency of organic carbon with marine sediments have been compiled for 69 locations. The burial efficiency as here defined is the ratio of the quantity of organic carbon which is ultimately buried to that which reaches the sediment-water interface. As noted previously, the sedimentation rate exerts a dominant influence on the burial efficiency. The logarithm of the burial efficiency is linearly related to the logarithm of the sedimentation rate at low sedimentation rates. At high sedimentation rates the burial efficiency can exceed 50% and becomes nearly independent of the sedimentation rate. The residual of the burial efficiency after the effect of the sedimentation rate has been subtracted is a weak function of the O2 concentration in bottom waters. The scatter is sufficiently large, so that the effect of the O2 concentration in bottom waters on the burial efficiency of organic matter could be either negligible or a minor but significant part of the mechanism that controls the level of O2 in the atmosphere.

  2. 60NiTi Intermetallic Material Evaluation for Lightweight and Corrosion Resistant Spherical Sliding Bearings for Aerospace Applications, Report on NASA-Kamatics SAA3-1288

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Jefferson, Michael

    2015-01-01

    Under NASA Space Act Agreement (SAA3-1288), NASA Glenn Research Center and the Kamatics subsidiary of the Kaman Corporation conducted the experimental evaluation of spherical sliding bearings made with 60NiTi inner races. The goal of the project was to assess the feasibility of manufacturing lightweight, corrosion resistant bearings utilizing 60NiTi for aerospace and industrial applications. NASA produced the bearings in collaboration with Abbott Ball Corporation and Kamatics fabricated bearing assemblies utilizing their standard reinforced polymer liner material. The assembled bearings were tested in oscillatory motion at a load of 4.54 kN (10,000 lb), according to the requirements of the plain bearing specification SAE AS81820. Several test bearings were exposed to hydraulic fluid or aircraft deicing fluid prior to and during testing. The results show that the 60NiTi bearings exhibit tribological performance comparable to conventional stainless steel (440C) bearings. Further, exposure of 60NiTi bearings to the contaminant fluids had no apparent performance effect. It is concluded that 60NiTi is a feasible bearing material for aerospace and industrial spherical bearing applications.

  3. Comparison of PLSR and SVM methods for predicting the organic carbon content using VNIR DRS at five locations with different soil types

    NASA Astrophysics Data System (ADS)

    Klement, Ales; Kodesova, Radka; Vasat, Radim; Fer, Miroslav; Brodsky, Lukas; Jaksik, Ondrej

    2015-04-01

    Visible and near-infrared diffuse reflectance spectroscopy (VNIR DRS) is cost- and time-effective and environmentally friendly techniques method used for prediction of soil properties. There are many studies dealing with this approach for particular conditions (single locality, different area size, etc.). This study was therefore focused on evaluating the suitability of VNIR DRS (400 - 2500 nm) for predicting organic carbon content, using samples collected at 5 agricultural lands from the municipalities of Brumovice (107 samples), Hostoun (58 samples), Sedlcany (78 samples), Vidim (86 samples) and Zelezna (69 samples). In Brumovice original soil type was Haplic Chernozem on loess, which was due to erosion changed into Regosol (steep parts) and Colluvial soil (base slope and the tributary valley). A similar process has been observed at other four locations Hostoun, Sedlcany, Vidim and Zelezna where the original soil types were Calcaric Leptosol, Haplic Cambisol on gneiss, Haplic Luvisol on loess and Haplic Cambisol on shales, respectively. Samples were taken from the topsoil within regular grid covering studied areas. Variable approaches may be applied to relate reflectance spectral data to particular soil property. Here were used Partial Least Square Regression (PLSR) and Support Vector Machine (SVM) with cross-validation to relate organic carbon content data to the reflectance spectral data by applying different preprocessing strategies. According to the criteria of minimal Root Mean Square Error of Prediction of Cross Validation (RMSEPcv) and maximal coefficient of determination (R2cv), the PLSR and SVMR models with raw spectra, the first and second derivative pretreatment provided the most accurate prediction for the organic carbon content from Brumovice (SVM, 1st. derivative, R2cv = 0.87, RMSEPcv = 0.11) and decreased as follows: Hostoun (PLSR, 2nd. derivative, R2cv = 0.69, RMSEPcv = 0.11), Sedlcany (SVM, 2nd. derivative, R2cv = 0.66, RMSEPcv = 0.17), Zelezna

  4. Carbon dioxide partial pressure and 13C content of north temperate and boreal lakes at spring ice melt

    USGS Publications Warehouse

    Striegl, R.G.; Kortelainen, Pirkko; Chanton, J.P.; Wickland, K.P.; Bugna, G.C.; Rantakari, M.

    2001-01-01

    Carbon dioxide (CO2) accumulates under lake ice in winter and degasses to the atmosphere after ice melt. This large springtime CO2 pulse is not typically considered in surface-atmosphere flux estimates, because most field studies have not sampled through ice during late winter. Measured CO2 partial pressure (pCO2) of lake surface water ranged from 8.6 to 4,290 Pa (85-4,230 ??atm) in 234 north temperate and boreal lakes prior to ice melt during 1998 and 1999. Only four lakes had surface pCO2 less than or equal to atmospheric pCO2, whereas 75% had pCO2 >5 times atmospheric. The ??13CDIC (DIC = ??CO2) of 142 of the lakes ranged from -26.28??? to +0.95.???. Lakes with the greatest pCO2 also had the lightest ??13CDIC, which indicates respiration as their primary CO2 source. Finnish lakes that received large amounts of dissolved organic carbon from surrounding peatlands had the greatest pCO2. Lakes set in noncarbonate till and bedrock in Minnesota and Wisconsin had the smallest pCO2 and the heaviest ??13CDIC, which indicates atmospheric and/or mineral sources of C for those lakes. Potential emissions for the period after ice melt were 2.36 ?? 1.44 mol CO2 m-2 for lakes with average pCO2 values and were as large as 13.7 ?? 8.4 mol CO2 m-2 for lakes with high pCO2 values.

  5. Impact of the addition of different plant residues on carbon-nitrogen content and nitrogen mineralization-immobilization turnover in a soil incubated under laboratory conditions

    NASA Astrophysics Data System (ADS)

    Abbasi, M. K.; Tahir, M. M.; Sabir, N.; Khurshid, M.

    2014-10-01

    Application of plant residues as soil amendment may represent a valuable recycling strategy that affects on carbon (C) and nitrogen (N) cycling, soil properties improvement and plant growth promotion. The amount and rate of nutrient release from plant residues depend on their quality characteristics and biochemical composition. A laboratory incubation experiment was conducted for 120 days under controlled conditions (25 °C and 58% water filled pore space (WFPS)) to quantify initial biochemical composition and N mineralization of leguminous and non-leguminous plant residues i.e. the roots, shoots and leaves of Glycine max, Trifolium repens, Zea mays, Poplus euramericana, Rubinia pseudoacacia and Elagnus umbellate incorporated into the soil at the rate of 200 mg residue N kg-1 soil. The diverse plant residues showed wide variation in total N, carbon, lignin, polyphenols and C/N ratio with higher polyphenol content in the leaves and higher lignin content in the roots. The shoot of G. max and the shoot and root of T. repens displayed continuous mineralization by releasing a maximum of 109.8, 74.8 and 72.5 mg N kg-1 and representing a 55, 37 and 36% of added N being released from these resources. The roots of G. max and Z. mays and the shoot of Z. mays showed continuous negative values throughout the incubation showing net immobilization. After an initial immobilization, leaves of P. euramericana, R. pseudoacacia and E. umbellate exhibited net mineralization by releasing a maximum of 31.8, 63.1 and 65.1 mg N kg-1, respectively and representing a 16, 32 and 33% of added N being released. Nitrogen mineralization from all the treatments was positively correlated with the initial residue N contents (r = 0.89; p ≤ 0.01), and negatively correlated with lignin content (r = -0.84; p ≤ 0.01), C/N ratio (r = -0.69; p ≤ 0.05), lignin/N ratio (r = -0.68; p ≤ 0.05), polyphenol/N ratio (r = -0.73; p ≤ 0.05) and ligin + polyphenol/N ratio (r = -0.70; p ≤ 0.05) indicating

  6. Influence of topographical features on the fluoride corrosion of Ni-Ti orthodontic archwires.

    PubMed

    Abalos, C; Paúl, A; Mendoza, A; Solano, E; Gil, F J

    2011-12-01

    Different manufacturing processes of Ni-Ti archwires respond differently to corrosion due to the surface conditions involved. In this study, several topographical features and their influence upon fluoride corrosion were studied. Four topographies (smooth, dimple, scratch, and crack) according to the main surface defect were characterized (n = 40). Static corrosion tests were performed in artificial saliva with fluorated prophylactic gel (12500 ppm) for 28 days. The surface was characterized by SEM and laser confocal microscopy. Standard electrochemical corrosion (open circuit potential, corrosion potential and corrosion current density) was performed. Statistical analysis was carried out using the ANOVA test (α ≤ 0.05). An increase was observed in the surface defects and/or roughness of the cracked and scratched surfaces. These defects produced an important increase in corrosion behavior. The best surfaces for the orthodontic archwires were the smooth and dimpled surfaces, respectively. The increase in defects was independent of roughness. Manufacturing processes that produce surface cracks should be avoided in orthodontic applications.

  7. Texture and Strain Measurements from Bending of NiTi Shape Memory Alloy Wires

    NASA Astrophysics Data System (ADS)

    Carl, Matthew; Zhang, Baozhuo; Young, Marcus L.

    2016-07-01

    Shape memory alloys (SMAs) are a new generation of materials that exhibit unique nonlinear deformations due to a phase transformation which allows the material to return to its original shape after removal of stress or a change in temperature. These unique properties are the result of a martensitic/austenitic phase transformation through the application of temperature changes or applied stress. Many technological applications of austenitic SMAs involve cyclical mechanical loading and unloading in order to take advantage of pseudoelasticity, but are limited due to poor fatigue life. In this paper, commercial pseudoelastic NiTi SMA wires (50.7 at.% Ni) were placed under different bending strains and examined using scanning electron microscopy and high-energy synchrotron radiation X-ray diffraction (SR-XRD). By observing the microstructure, phase transformation temperatures, surface texture and diffraction patterns along the wire, it is shown that the wire exhibits a strong anisotropic behavior whether on the tensile or compressive side of the bending axis and that the initiation of micro-cracks in the wires is localized on the compression side, but that crack propagation will still happen if the wire is reloaded in the opposite direction. In addition, lattice strains are examined for both the austenite and martensite phases.

  8. Crystallization study of amorphous sputtered NiTi bi-layer thin film

    SciTech Connect

    Mohri, Maryam; Nili-Ahmadabadi, Mahmoud; Chakravadhanula, Venkata Sai Kiran

    2015-05-15

    The crystallization of Ni-rich/NiTiCu bi-layer thin film deposited by magnetron sputtering from two separate alloy targets was investigated. To achieve the shape memory effect, the NiTi thin films deposited at room temperature with amorphous structure were annealed at 773 K for 15, 30, and 60 min for crystallization. Characterization of the films was carried out by differential scanning calorimetry to indicate the crystallization temperature, grazing incidence X-ray diffraction to identify the phase structures, atomic force microscopy to evaluate surface morphology, scanning transmission electron microscopy to study the cross section of the thin films. The results show that the structure of the annealed thin films strongly depends on the temperature and time of the annealing. Crystalline grains nucleated first at the surface and then grew inward to form columnar grains. Furthermore, the crystallization behavior was markedly affected by composition variations. - Highlights: • A developed bi-layer Ni45TiCu5/Ni50.8Ti was deposited on Si substrate and crystallized. • During crystallization, The Ni{sub 45}TiCu{sub 5} layer is thermally less stable than the Ni-rich layer. • The activation energy is 302 and 464 kJ/mol for Cu-rich and Ni-rich layer in bi-layer, respectively.

  9. Load bearing and stiffness tailored NiTi implants produced by additive manufacturing: a simulation study

    NASA Astrophysics Data System (ADS)

    Rahmanian, Rasool; Shayesteh Moghaddam, Narges; Haberland, Christoph; Dean, David; Miller, Michael; Elahinia, Mohammad

    2014-03-01

    Common metals for stable long-term implants (e.g. stainless steel, Titanium and Titanium alloys) are much stiffer than spongy cancellous and even stiffer than cortical bone. When bone and implant are loaded this stiffness mismatch results in stress shielding and as a consequence, degradation of surrounding bony structure can lead to disassociation of the implant. Due to its lower stiffness and high reversible deformability, which is associated with the superelastic behavior, NiTi is an attractive biomaterial for load bearing implants. However, the stiffness of austenitic Nitinol is closer to that of bone but still too high. Additive manufacturing provides, in addition to the fabrication of patient specific implants, the ability to solve the stiffness mismatch by adding engineered porosity to the implant. This in turn allows for the design of different stiffness profiles in one implant tailored to the physiological load conditions. This work covers a fundamental approach to bring this vision to reality. At first modeling of the mechanical behavior of different scaffold designs are presented as a proof of concept of stiffness tailoring. Based on these results different Nitinol scaffolds can be produced by additive manufacturing.

  10. The Influence of the R-Phase on the Superelastic Behavior of NiTi

    NASA Astrophysics Data System (ADS)

    Duerig, T. W.; Bhattacharya, K.

    2015-06-01

    Approximately equiatomic Ni-Ti alloys, or Nitinol, can transform upon cooling or when stressed from a parent ordered cubic (B2) Austenite phase into two martensitic structures: a monoclinic structure commonly referred to as simply martensite and a rhombohedrally distorted martensite referred to as the R-phase. While the former is often more stable, the R-phase presents a substantially lower barrier to formation, creating an interesting competition for the succession of Austenite. This competition has markedly different outcomes depending upon whether Austenite instability is caused by cooling or by the application of stress. While medical applications are generally used isothermally, most characterization is done using thermal scans such as differential scanning calorimetry. This leads to frequent and significant misunderstandings regarding plateau stresses in particular. The purpose of this paper is to discuss the competition between these two martensites as the parent Austenite phase loses stability, and to clarify how tests can be properly conducted and interpreted to avoid confusion. To that end, the examples shown are not selected to be ideal or theoretical, but rather to illustrate complexities typical of those found in medical devices, such as cold worked conditions that make peaks difficult to interpret and "plateaus" ill-defined. Finally, a stress-induced M ⇒ R ⇒ M sequence will be discussed.

  11. Fatigue of NiTi SMA-pulley system using Taguchi and ANOVA

    NASA Astrophysics Data System (ADS)

    Mohd Jani, Jaronie; Leary, Martin; Subic, Aleksandar

    2016-05-01

    Shape memory alloy (SMA) actuators can be integrated with a pulley system to provide mechanical advantage and to reduce packaging space; however, there appears to be no formal investigation of the effect of a pulley system on SMA structural or functional fatigue. In this work, cyclic testing was conducted on nickel-titanium (NiTi) SMA actuators on a pulley system and a control experiment (without pulley). Both structural and functional fatigues were monitored until fracture, or a maximum of 1E5 cycles were achieved for each experimental condition. The Taguchi method and analysis of the variance (ANOVA) were used to optimise the SMA-pulley system configurations. In general, one-way ANOVA at the 95% confidence level showed no significant difference between the structural or functional fatigue of SMA-pulley actuators and SMA actuators without pulley. Within the sample of SMA-pulley actuators, the effect of activation duration had the greatest significance for both structural and functional fatigue, and the pulley configuration (angle of wrap and sheave diameter) had a greater statistical significance than load magnitude for functional fatigue. This work identified that structural and functional fatigue performance of SMA-pulley systems is optimised by maximising sheave diameter and using an intermediate wrap-angle, with minimal load and activation duration. However, these parameters may not be compatible with commercial imperatives. A test was completed for a commercially optimal SMA-pulley configuration. This novel observation will be applicable to many areas of SMA-pulley system applications development.

  12. A comparison of the shaping ability of reciprocating NiTi instruments in simulated curved canals

    PubMed Central

    Yoo, Young-Sil

    2012-01-01

    Objectives The study was to compare the shaping ability of Reciproc (VDW) and WaveOne (Dentsply Maillefer) instruments compared with ProTaper, Profile and hand instrument during the preparation of simulated root canals. Materials and Methods Five groups (n = 5) were established. Reciproc, WaveOne, ProTaper, Profile and K file (K-flexo file) were used to prepare the resin simulated canals. A series of preoperative and postoperative images were taken by a microscope and superimposed in 2 different layers. The amount of resin removed from both the inner and the outer sides of the canal was measured to the level of 10 mm from the apical tip, with a 1 mm increment. Results The mean of resin removal from the inner canal wall was not different from the outer canal wall for Reciproc and WaveOne groups at apical third (1 - 3 mm level). There was no difference in the change of working length and maintenance of canal curvature. NiTi instruments are superior to stainless-steel K file in their shaping ability. Conclusions Within the limitation of this present study, Reciproc and WaveOne instruments maintained the original canal curvature in curved canals better than ProTaper and Profile, which tend to transport towards the outer canal wall of the curve in the apical part of the canal. PMID:23430033

  13. Surface characterizations of laser modified biomedical grade NiTi shape memory alloys.

    PubMed

    Pequegnat, A; Michael, A; Wang, J; Lian, K; Zhou, Y; Khan, M I

    2015-05-01

    Laser processing of shape memory alloys (SMAs) promises to enable the multifunctional capabilities needed for medical device applications. Prior to clinical implementation, the surface characterisation of laser processed SMA is essential in order to understand any adverse biological interaction that may occur. The current study systematically investigated two Ni-49.8 at.% Ti SMA laser processed surface finishes, including as-processed and polished, while comparing them to a chemically etched parent material. Spectrographic characterisation of the surface included; X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), and Raman spectroscopy. Corrosion performance and Ni ion release were also assessed using potentiodynamic cyclic polarization testing and inductively coupled plasma optical emission spectroscopy (ICP-OES), respectively. Results showed that surface defects, including increased roughness, crystallinity and presence of volatile oxide species, overshadowed any possible performance improvements from an increased Ti/Ni ratio or inclusion dissolution imparted by laser processing. However, post-laser process mechanical polishing was shown to remove these defects and restore the performance, making it comparable to chemically etched NiTi material.

  14. Simulating Thermal Cycling and Isothermal Deformation Response of Polycrystalline NiTi

    NASA Technical Reports Server (NTRS)

    Manchiraju, Sivom; Gaydosh, Darrell J.; Noebe, Ronald D.; Anderson, Peter M.

    2011-01-01

    A microstructure-based FEM model that couples crystal plasticity, crystallographic descriptions of the B2-B19' martensitic phase transformation, and anisotropic elasticity is used to simulate thermal cycling and isothermal deformation in polycrystalline NiTi (49.9at% Ni). The model inputs include anisotropic elastic properties, polycrystalline texture, DSC data, and a subset of isothermal deformation and load-biased thermal cycling data. A key experimental trend is captured.namely, the transformation strain during thermal cycling is predicted to reach a peak with increasing bias stress, due to the onset of plasticity at larger bias stress. Plasticity induces internal stress that affects both thermal cycling and isothermal deformation responses. Affected thermal cycling features include hysteretic width, two-way shape memory effect, and evolution of texture with increasing bias stress. Affected isothermal deformation features include increased hardening during loading and retained martensite after unloading. These trends are not captured by microstructural models that lack plasticity, nor are they all captured in a robust manner by phenomenological approaches. Despite this advance in microstructural modeling, quantitative differences exist, such as underprediction of open loop strain during thermal cycling.

  15. High Strain Rate Compression of Martensitic NiTi Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Qiu, Ying; Young, Marcus L.; Nie, Xu

    2015-09-01

    The compressive response of martensitic NiTi shape memory alloys (SMAs) under high strain rate (1200 s-1) was investigated on a modified Kolsky (Split Hopkinson) compression bar. The single-loading momentum trapping system ensures precise deformation control (1.4, 1.8, 3.0, 4.8, and 9.6 % strain) and single loading during dynamic compression. With increasing strain, the phase transformation peaks shift toward lower temperatures, while the intensities of these peaks decrease and eventually disappear completely at strains above 7 %, where the onset of plastic deformation of reoriented martensite occurs. All transformation peaks are recoverable after deformation simply by annealing at 873 K (600 °C) for 30 min, except those peaks corresponding to strains above 7 % (e.g., 9.6 %) which return upon annealing, but at a lower temperature. XRD results showed the variation of the strongest diffraction peak from (1bar{1}1) to (111) crystal plane before and after high strain rate compression.

  16. Surface characterizations of laser modified biomedical grade NiTi shape memory alloys.

    PubMed

    Pequegnat, A; Michael, A; Wang, J; Lian, K; Zhou, Y; Khan, M I

    2015-05-01

    Laser processing of shape memory alloys (SMAs) promises to enable the multifunctional capabilities needed for medical device applications. Prior to clinical implementation, the surface characterisation of laser processed SMA is essential in order to understand any adverse biological interaction that may occur. The current study systematically investigated two Ni-49.8 at.% Ti SMA laser processed surface finishes, including as-processed and polished, while comparing them to a chemically etched parent material. Spectrographic characterisation of the surface included; X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), and Raman spectroscopy. Corrosion performance and Ni ion release were also assessed using potentiodynamic cyclic polarization testing and inductively coupled plasma optical emission spectroscopy (ICP-OES), respectively. Results showed that surface defects, including increased roughness, crystallinity and presence of volatile oxide species, overshadowed any possible performance improvements from an increased Ti/Ni ratio or inclusion dissolution imparted by laser processing. However, post-laser process mechanical polishing was shown to remove these defects and restore the performance, making it comparable to chemically etched NiTi material. PMID:25746282

  17. Thermal Cycling and Isothermal Deformation Response of Polycrystalline NiTi: Simulations vs. Experiment

    NASA Technical Reports Server (NTRS)

    Manchiraju, Sivom; Gaydosh, Darrell; Benafan, Othmane; Noebe, Ronald; Vaidyanathan, Raj; Anderson, Peter M.

    2011-01-01

    A recent microstructure-based FEM model that couples crystal-based plasticity, the B2<-> MB190 phase transformation and anisotropic elasticity at the grain scale is calibrated to recent data for polycrystalline NiTi (49.9 at.% Ni). Inputs include anisotropic elastic properties, texture and differential scanning calorimetry data, as well as a subset of recent isothermal deformation and load-biased thermal cycling data. The model is assessed against additional experimental data. Several experimental trends are captured - in particular, the transformation strain during thermal cycling monotonically increases and reaches a peak with increasing bias stress. This is achieved, in part, by modifying the martensite hardening matrix proposed by Patoor et al. [Patoor E, Eberhardt A, Berveiller M. J Phys IV 1996;6:277]. Some experimental trends are underestimated - in particular, the ratcheting of macrostrain during thermal cycling. This may reflect a model limitation that transformation-plasticity coupling is captured on a coarse (grain) scale but not on a fine (martensitic plate) scale.

  18. Late Quaternary Upwelling Variations in the Eastern Equatorial Atlantic Ocean as Inferred from Dinoflagellate Cysts, Planktonic Foraminifera, and Organic Carbon Content

    NASA Astrophysics Data System (ADS)

    Höll, Christine; Kemle-von Mücke, Sylvia

    2000-07-01

    Analysis of multiple proxies shows that eastern equatorial Atlantic upwelling was subdued during isotope stage 5.5, more intense during stages 4, 5.2, 5.4, and 6, and most intense early in stage 2. These findings are based on proxy measures from a core site about 600 km southwest of Liberia. The proxies include total organic carbon content, the ratio of peridinoid and oceanic organic-walled dinoflagellate cyst species, accumulation rates of calcareous dinoflagellates, estimates of sea surface paleotemperatures, the difference in stable oxygen isotope composition between two species of planktonic foraminifera that live at different water depths, and the abundance of the planktonic foraminifera Neogloboquadrina dutertrei. Most of these parameters consistently vary directly or inversely with one another. Slight discrepancies between the individual parameters show the usefulness of a multiple proxy approach to reconstruct paleoenvironments. Our data confirm that northern summer insolation strongly influences upwelling in the eastern equatorial Atlantic Ocean.

  19. Deep Ocean Circulation and Nutrient Contents from Atlantic-Pacific Gradients of Neodymium and Carbon Isotopes During the Last 1 Ma

    NASA Astrophysics Data System (ADS)

    Piotrowski, A. M.; Elderfield, H.; Howe, J. N. W.

    2014-12-01

    The last few million years saw changing boundary conditions to the Earth system which set the stage for bi-polar glaciation and Milankovich-forced glacial-interglacial cycles which dominate Quaternary climate variability. Recent studies have highlighted the relative importance of temperature, ice volume and ocean circulation changes during the Mid-Pleistocene Transition at ~900 ka (Elderfield et al., 2012, Pena and Goldstein, 2014). Reconstructing the history of global deep water mass propagation and its carbon content is important for fully understanding the ocean's role in amplifying Milankovich changes to cause glacial-interglacial transitions. A new foraminiferal-coating Nd isotope record from ODP Site 1123 on the deep Chatham Rise is interpreted as showing glacial-interglacial changes in the bottom water propagation of Atlantic-sourced waters into the Pacific via the Southern Ocean during the last 1 million years. This is compared to globally-distributed bottom water Nd isotope records; including a new deep western equatorial Atlantic Ocean record from ODP Site 929, as well as published records from ODP 1088 and Site 1090 in the South Atlantic (Pena and Goldstein, 2014), and ODP 758 in the deep Indian Ocean (Gourlan et al., 2010). Atlantic-to-Pacific gradients in deep ocean neodymium isotopes are constructed for key time intervals to elucidate changes in deep water sourcing and circulation pathways through the global ocean. Benthic carbon isotopes are used to estimate deep water nutrient contents of deep water masses and constrain locations and modes of deep water formation. References: Elderfield et al. Science 337, 704 (2012) Pena and Goldstein, Science 345, 318 (2014) Gourlan et al., Quaternary Science Reviews 29, 2484-2498 (2010)

  20. Study of electric properties of amorphous AgGe1+xAs1-xS3 with content of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Melnikova, Nina; Kurochka, Kirill; Volkova, Yana

    2013-06-01

    Multicomponent copper and silver chalcogenides have been known as promising materials for scientific and applied purposes. These materials are also under intense investigation for application in a phase-change random access memory. In order to obtain materials with a high ionic conductivity component, glassy silver chalcogenides AgGe1+xAs1-xS3 with the addition of nanotubes were synthesized. In this work the study of electrical properties of the amorphous chalcogenide AgGe1.4As0.6S3 (x = 0.4) with carbon nanotube content at a frequency of the alternating-current electric field varying from 1 Hz to 5 MHz and on direct current at ambient pressure and at pressure up to 30 GPa are presented. The ion transport was confirmed by means DC measurements in cells with blocking ion component of conductivity electrodes. An evaluation of the proportion of ionic conductivity can make a preliminary conclusion that the ionic component of the conductivity of at least 98%. Analyze of the baric dependences of AC properties have shown that the dielectric loss tangent and the real part of an admittance of the AgGe1.4As0.6S3 with carbon nanotube content compound exponentially increase with a pressure increase from 1 up to 30 GPa. The study was supported in part by the Ural Federal University development program with the financial support of young scientists; and by the Russian Foundation for Basic Research, project No. 12-02-31607.

  1. A Soil Carbon Cycle Without Life?: The Content and Residence Times of Organic and Inorganic Carbon in the Atacama Desert of Chile

    NASA Astrophysics Data System (ADS)

    Amundson, R. G.; Navarro-Gonzalez, R.; Ewing, S. A.

    2003-12-01

    The central Atacama Desert of Chile is nearly rainless and virtually devoid of biota. Precipitation increases steadily as one moves to more southern latitudes, providing a natural experiment to assess the role of water in the soil C cycle. We have established three research sites along this gradient, where the mean annual precipitation varies from nearly 0 to about 15 mm y-1. At the driest site, where plants are completely absent and soil microorganisms quite rare, trace quantities of organic C (OC) are present ( ˜0.009+/-0.0038%), and OC increases slightly with precipitation (and the increasing presence of vegetation) to 0.053%. The apparent radiocarbon age of the organic matter at the driest site is exceedingly old (> 7,000 y), suggesting C cycling rates on the order of 104 y. The source of the incoming C is being investigated, and may include a combination of marine aerosols and exceedingly rare cyanobacteria on the undersides of quartz clasts ("hypoliths"). Radiocarbon-based turnover times appear to increase to decadal scales with increasing rainfall, with annually cycling OC concentrated in coppice dunes (0.32% OC) and hypolith-associated soils (0.39% OC). The radiocarbon age of co-existing soil carbonate was ˜12,000 years at the driest site and thus older than that of the OC, suggesting limited weathering and incorporation of modern atmospheric CO2 with increasing precipitation. The character of the organic matter present in the soil was analyzed by pyrolysis-GC-MS. The main organic molecules released at 750° C in an inert atmosphere are benzene and formic acid. Their concentrations in the driest soil are in the ppb range, and decrease by about an order of magnitude with depth. This suggests that either the environmental conditions in the past were much more severe or else that there are slow downward fluxes of organic materials accompanied by decomposition (either biologi