Academic literature on the topic 'Carbon globules'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Carbon globules.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Carbon globules"
1
Zaikovskii, Alexey. "Structural Features of the Carbon Material Synthesized by Plasma-Arc Method at Low Buffer Gas Pressure." Applied Mechanics and Materials 864 (April 2017): 36–41. http://dx.doi.org/10.4028/www.scientific.net/amm.864.36.
Full textAbstract:
The carbon material was synthesized by the plasma-arc method at the buffer gas pressure of 3 Torr. The material has physical properties different from the properties of the material synthesized at pressure of 25 Torr and higher. The low pressure of buffer gas leads to formation of materials consisting of carbon nanoparticles with average size lower than 10nm. The nanoparticles have form of carbon globules, which consist of the graphite-like structure. This structure is the composition of the stacked, twisted and closed nanofragments of graphene. The dominating interlayer distance in the structure is 0.4 nm. The dominating size of crystallinity La is 2.7nm. The graphite-like structure allows to enhance the electrical conductivity in compare with the material synthesized at buffer gas pressure of 25 Torr and higher. Nevertheless the conductivity of the material is significantly lower than the conductivity of pure graphite because of the contact resistance arising from the presence of the outer layer of amorphous carbon on some globules and the presence of the globules of fully amorphous carbon.
2
Razd’yakonova, G. I., V. A. Likholobov, O. A. Kokhanovskaya, and E. A. Kiseleva. "Compaction of dispersed carbon globules by their consolidation." Solid Fuel Chemistry 48, no. 3 (May 2014): 198–202. http://dx.doi.org/10.3103/s0361521914030070.
Full text
3
Pavlyuchenko, P. E., G. M. Seropyan, M. V. Trenikhin, and V. A. Drozdov. "STRUCTURAL TRANSFORMATIONS OF CARBON NANOMATERIAL UNDER INFLUENCE OF HIGH ENERGY LASER IRRADIATION." Российский химический журнал 62, no. 1-2 (February 1, 2019): 171–80. http://dx.doi.org/10.6060/rcj.2018621-2.14.
Full textAbstract:
Laser pulse irradiation of the globular turbostratic carbon material in various conditions was carried out in this work. It was investigated by TEM that the formation of nanostructured particles (nanocapsules) during irradiation at 1064 nm wavelength occurs with power density of 108 W/cm2, and it’s rise up to 1011 W/cm2 leads to increase the degree of ordering of the obtained structures. It is shown that irradiation of the initial globules with pulses at 532 nm wavelength allows to reduce the interplanar spacing of graphene layers from 0,410 nm to 0,346 nm in the formed nanocapsules. The dependence of the maximum heating temperature of nanoparticles on the energy density on the laser spot was analyzed. The influence of the heating temperature of the carbon nanomaterial on structure and morphology was stated.
4
Kumar, Rajeev, Harish Kumar Choudhary, Shital Patangrao Pawar, Suryasarathi Bose, and Balaram Sahoo. "Carbon encapsulated nanoscale iron/iron-carbide/graphite particles for EMI shielding and microwave absorption." Physical Chemistry Chemical Physics 19, no. 34 (2017): 23268–79. http://dx.doi.org/10.1039/c7cp03175k.
Full text
5
Young, K., P. Cox, P. J. Huggins, T. Forveille, and R. Bachiller. "Neutral Atomic Carbon in the Globules of the Helix." Astrophysical Journal 482, no. 1 (June 10, 1997): L101—L104. http://dx.doi.org/10.1086/310677.
Full text
6
Kim, H. G., and S. S. Hong. "Carbon monoxide observations of small dark globules: II. Stability analysis." New Astronomy 14, no. 5 (July 2009): 451–60. http://dx.doi.org/10.1016/j.newast.2008.12.006.
Full text
7
Kim, H. G., and S. S. Hong. "Carbon Monoxide Observations of Small Dark Globules. I. Internal Structure." Astrophysical Journal 567, no. 1 (March 2002): 376–90. http://dx.doi.org/10.1086/338416.
Full text
8
Silaev, V. I., G. A. Karpov, L. P. Anikin, E. A. Vasiliev, L. P. Vergasova, and I. V. Smoleva. "Mineral-phase paragenes in explosive products of modern emergencies of Kamchatka and Kuril volcanoes. Part 1. Diamonds, carbon phases, condensed organoids." Вулканология и сейсмология, no. 5 (August 15, 2019): 54–67. http://dx.doi.org/10.31857/s0203-03062019554-67.
Full textAbstract:
In the products of modern volcanic identified carbonaceous mineral phase paragenes explosive-atmoelektrogenese origin comprising diamond cuboctahedral habitus with non-aggregated nitrogen defects (no signs mantle annealing), disordered graphite, shungito shaped asphalts (kerite-anthraxolite), carbon globules – cluster allotrope diuglerod composition, metallo-carbon nanomicrocomposites – a product of the shock-thermal decomposition of organometallic compounds and a biogenic organic compounds. The identified carbon paragenes is considered as a unique natural phenomenon indicating the existence of a global process of endogenous carbonization of the Earth's crust during the course of the crust-mantle interactions.
9
Rogal, Lukasz, and Jan Dutkiewicz. "Transmission Electron Microscopy Studies of X210CrW12 and 100CR6 Thixo-Cast Steels." Solid State Phenomena 186 (March 2012): 311–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.186.311.
Full textAbstract:
Two kinds of deformed carbon steel were used as a feedstock for thixoforming: X210CrW12 tool steel cold worked, of composition 2,1 %C, 10,5 %Cr, 0,7 %W, 0,4 %Si (all in weight %), and bearing steel 100Cr6: (0,9% C, 1,4% Cr, 0,4% Mn, 0,3% Si, 0,2% Cu). The microstructures of X210CrW12 steel after thixoforming process at temperature of 1230°C, performed at 30 % of liquid show presence of globular grains (average size from 30 µm 50 µm) surrounded by the eutectic mixture. Measured chemical composition of the austenite in globules was: 2,5% C, 0,4% Si, 0,7% Mn, 12% Cr, 1,3% W, 0,1%V, 87% Fe and that of the eutectic mixture: 5%C, 0,4% Si, 0,6%, Mn, 1,1%, W, 17,5% Cr, 75,4% Fe in thixocast of X210CrW12 steel. Measured carbon content is too high, most probably due to contamination effect. TEM studies of this steel after thixoforming shows that the eutectic mixture consists of ferrite α-Fe and Cr7C3 carbides. Thixoforming of 100Cr6 bearing steel was conducted at temperature of 1420°C at about 25 % of liquid fraction. Thixocast microstructure consists of globular grains consisting of martensite needles and residual austenite (20 μm to 40 μm in size and average composition 0,9%C, 1,4 %Cr, 0,5%Mn, 0,3%Si). The chemical composition of the eutectic is following: 2,4% C, 2,6% Cr, 0,2%Si, 0,6%Mn.
10
Kumar, Rajeev, and Balaram Sahoo. "Carbon nanotubes or carbon globules: Optimization of the pyrolytic synthesis parameters and study of the magnetic properties." Nano-Structures & Nano-Objects 14 (April 2018): 131–37. http://dx.doi.org/10.1016/j.nanoso.2018.01.014.
Full textDissertations / Theses on the topic "Carbon globules"
1
Martell, Sarah L. "Carbon and nitrogen abundance variations in globular cluster red giants /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2008. http://uclibs.org/PID/11984.
Full text
2
Barreiro, Susana Miguel. "Development of forest simulation tools for assessing the impact of different management strategies and climatic changes on wood production and carbon sequestration for Eucalyptus in Portugal." Doctoral thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5216.
Full textAbstract:
Doutoramento em Engenharia Florestal e dos Recursos Florestais - Instituto Superior de AgronomiaThe present work had as main objective developing tools capable of simulating the evolution of Eucalyptus globulus forests in Portugal taking into account disturbance factors, such as market demands, hazards occurrence, land use changes, forest management and/or climate changes. Some conceptual work was done concerning the definition of different forest management alternatives while at the same time the E. globulus current management was described. SIMPLOT, a regional simulator based on national forest inventory plots was developed and validated. This simulation tool, mainly driven by wood and biomass demands, takes into account the occurrence of hazards, land use changes and the changes between different forest management alternatives allowing accessing its long-term impacts, namely on wood production and carbon sequestration. Some of the empirical growth models available for this species in Portugal were integrated into this simulator. However, the need to forecast the growth of highly stocked stands managed for bioenergy lead to the development of a new model. In order to account for climate changes, a process-based model was required. Therefore, the applicability of 3PG process-based model at a regional scale was tested for planted and coppice stands. Two forest level simulators, 3PG-Out+ and GLOBULUS, were developed along this study.
3
Carvalho, Ana Paula Vilela. "Produtividade de minicepas de eucalipto sob aplicação de CO 2 via água de irrigação." Universidade Federal de Viçosa, 2015. http://www.locus.ufv.br/handle/123456789/7284.
Full textAbstract:
Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2016-02-17T15:27:35Z
No. of bitstreams: 1
texto completo.pdf: 1190985 bytes, checksum: 33b3ec9621e048129058b435303c3f71 (MD5)Made available in DSpace on 2016-02-17T15:27:35Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1190985 bytes, checksum: 33b3ec9621e048129058b435303c3f71 (MD5) Previous issue date: 2015-07-07
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Este trabalho teve como objetivo estudar a influência do CO 2 aplicado via água de irrigação na produtividade de minicepas, enraizamento de miniestacas, trocas gasosas e variáveis ecofisiológicas em minicepas de híbridos de Eucalyptus globulus e Eucalyptus grandis. Para tanto, experimentos foram conduzidos no Viveiro de Pesquisa do Departamento de Engenharia Florestal da Universidade Federal de Viçosa, Minas Gerais. O delineamento experimental utilizado foi em blocos ao acaso, com parcelas subdivididas, avaliando-se cinco clones, sendo: dois clones de Eucalyptus urophylla x E. globulus (C1 e C2); dois clones de Eucalyptus grandis x E. globulus (C3 e C4) e um clone de Eucalyptus urophylla x E. grandis (C5) e cinco doses de CO 2 aplicadas via água de irrigação (0, 3, 6, 12 e 18 L m -2 dia -1 ) com três repetições. No primeiro capítulo, foi avaliada a produtividade de minicepas e a biomassa de miniestacas dos clones C1, C2, C3, C4 e C5; porcentagem de sobrevivência e enraizamento das miniestacas e qualidade das mudas aos 30 dias de enraizamento provenientes de minicepas dos clones C1, C3 e C5, sob a aplicação do CO 2, via água de irrigação no período do verão-E1 e período do outono-E2. Os clones C1, C2, C3, C4 e C5 responderam de maneira semelhante ao tratamento com CO 2, aplicado via água de irrigação, quanto à produtividade de miniestacas/minicepa/semana e biomassa de miniestacas e os clones C1, C3 e C5 em relação à porcentagem de sobrevivência e enraizamento das miniestacas na saída da casa de vegetação nos dois períodos de avaliação do verão e outono. No período do outono, a aplicação do CO 2, via água de irrigação, influenciou positivamente na qualidade das mudas do clone C1 e nos clones C3 e C5 e houve redução da qualidade das mudas a partir da dose de 6 L m -2 dia -1. No segundo capítulo, foi estudada fotossíntese líquida (A), condutância estomática (gs), taxa de transpiração (E), razão entre concentração interna e externa de CO 2 (Ci/Ca) e eficiência do uso da água de minicepas de um clone de Eucalyptus urophylla x E. globulus (C1); um clone de Eucalyptus grandis x E. globulus (C3) e um clone de Eucalyptus urophylla x E. grandis (C5) e eficiência quântica (α) de um clone híbrido de Eucalyptus: Eucalyptus viiiurophylla x E. globulus (C1) em três experimentos, E1, E2 e E3, respectivamente, período do verão, outono e inverno de 2014. As trocas gasosas das minicepas foram mensuradas com o auxilio de um analisador de gás por infravermelho (IRGA). Os clones C1, C3 e C5 responderam de maneira semelhante ao tratamento com CO 2 aplicado via água de irrigação quanto à fotossíntese, condutância estomática, transpiração, razão entre concentração interna e externa de CO 2 (Ci/Ca) e eficiência do uso da água nos períodos do verão, outono e inverno. A maior dose de CO 2, aplicada via água de irrigação, proporcionou o melhor desempenho do C1 na eficiência quântica no E1, período com temperatura média diária de 18,6oC. No E2, período com temperatura média diária de 22,6oC, o C1 atingiu melhor desempenho na eficiência quântica com as doses de 3 L m -2 dia -1 e 12 L m -2 dia -1.
This work aimed to study the influence of CO 2 applied through irrigation water in mini-stumps productivity, rooting of mini-cuttings, gas exchange and ecophysiological variables in mini-stumps hybrid of Eucalyptus grandis and Eucalyptus globulus. For this, experiments were conducted at the Research Nursery of the Department of Forestry of the Federal University of Viçosa, Minas Gerais. The experimental design was a randomized blocks with split plots evaluating five clones, as follows: two clones of Eucalyptus urophylla x E. globulus (C1 and C2); Two clones of Eucalyptus grandis x E. globulus (C3 and C4) and a clone E. urophylla x E. grandis (C5) and five doses of CO 2 applied through irrigation water (0, 3, 6, 12 and 18 L m -2 day -1 ) with three replications. In the first chapter, mini-stumps productivity was evaluated and mini-cuttings biomass of clones C1, C2, C3, C4 and C5; percentage of survival and rooting of the mini-cuttings and quality of seedlings at 30 days of rooting from mini-stumps of clones clones C1, C3 and C5 in the application of CO 2 through irrigation water in E1-summer period and autumn-E2 period. The clones C1, C2, C3, C4 and C5 respond similarly to treatment with CO 2 applied through irrigation water for productivity mini-cuttings/mini-stump/week and biomass mini-cuttings and the clones C1, C3 and C5 in relation to the percentage of survival and rooting of mini-cuttings in the greenhouse output in both evaluation periods summer and autumn. In the autumn term application of CO 2 through irrigation water positively influence the quality seedlings of clone C1 and C3 and C5 clones there was reduction of quality seedlings starting dose of 6 L m -2 day -1 . In the second chapter, was studied net photosynthesis (A), stomatal conductance (gs), transpiration rate (E), the ratio between internal and external CO 2 concentration (Ci/Ca) and water use efficiency a clone of the mini-stumps Eucalyptus urophylla x E. globulus (C1); one clone of Eucalyptus grandis x E. globulus (C3) and a clone Eucalyptus urophylla x E. grandis (C5) and quantum efficiency (α), a hybrid clone Eucalyptus: Eucalyptus globulus x E. urophylla (C1) into three experiments, E1, E2 and E3, respectively, summer period, autumn and winter 2014. The gas exchange of xmini-stumps were measured with the aid of an infrared gas analyzer (IRGA). The clones C1, C3 and C5 responded similarly to treatment with CO 2 applied through irrigation water on the photosynthesis, stomatal conductance, transpiration, the ratio between internal and external CO 2 concentration (Ci/Ca) and water use efficiency in periods summer, autumn and winter. The highest dose of CO 2 applied through irrigation water provided the best performance of C1 in quantum efficiency in E1, period average daily temperature of 18,6oC. In E2, period average daily temperature of 22,6oC, the C1 reached the best performance in quantum efficiency with doses of 3 L m -2 day -1 and 12 L m -2 day -1 .
4
Sausen, Tanise Luisa. "Estoque e dinâmica de carbono em plantios subtropicais de Eucalyptus saligna e Mediterrâneos de Eucalyptus globulus." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/29596.
Full textAbstract:
O continuo aumento na concentração de dióxido de carbono na atmosfera, resultado da combustão de combustíveis fósseis, de mudanças no uso do solo e do desmatamento para a agricultura, é um assunto de grande importância devido a suas implicações no aquecimento global e nas mudanças climáticas. O florestamento é visto como uma solução para frear o aumento na concentração de CO2 atmosférico, podendo contribuir na mitigação das mudanças climáticas através do seqüestro de carbono na biomassa das árvores e no solo. O presente estudo teve como objetivo avaliar alguns dos processos que envolvem o estoque e a dinâmica do carbono em sistemas florestais manejados com eucalipto. O estudo abrangeu trabalhos de campo para quantificar o estoque de carbono nos componentes do sistema florestal com árvores de Eucalyptus saligna com três anos de idade na região Sul do Brasil e a investigação do efeito de variações sazonais e ontogenéticas sobre as emissões respiratórias de CO2 das folhas e do caule de Eucalyptus globulus com 6 e 11 anos de idade sob clima Mediterrâneo na região central de Portugal. Os resultados do experimento de campo realizado no Brasil mostraram que a biomassa do caule representa o principal pool de carbono no sistema florestal (média de 68% do estoque total), seguido pelo solo (média de 30%) enquanto que os pools mais lábeis de carbono, como a biomassa das folhas, raízes e a serrapilheira representam uma menor proporção do estoque total de carbono (média de 2%). O teor de argila e o conteúdo gravimétrico de água no solo foram positivamente relacionados com as variações observadas no estoque de carbono no solo e na biomassa de folhas e do caule. O acúmulo de carbono no solo não foi associado com a produção e composição química de serrapilheira. Por outro lado, as variações observadas no estoque de carbono nas frações do solo (carbono associado a minerais e carbono orgânico particulado) foram significativamente associadas com as características do solo, principalmente o teor de argila e a concentração de cobre; e com a composição química das raízes. As relações observadas entre as características do solo e das raízes com as frações de carbono associado a minerais e de carbono orgânico particulado parecem estar associadas com a função dessas variáveis sobre os processos de decomposição e estabilização da matéria orgânica no solo. Os resultados do experimento de campo conduzido em Portugal evidenciaram que a medida que as árvores tornam-se maiores e mais velhas ocorre um aumento nas perdas respiratórias de CO2 das folhas e do caule. Entretanto, o acentuado aumento observado nas emissões respiratórias nas árvores mais velhas (11 anos) ocorreu apenas durante o outono, sendo associado com a recuperação do status hídrico da planta após um período de déficit hídrico durante o verão. O aumento na respiração foliar e do caule nas árvores mais velhas após a recuperação do turgor celular durante o outono parece estar relacionado com o aumento na energia requerida para os processos de manutenção celular mais do que aos processos de respiração de crescimento. Os resultados deste estudo indicaram que em sistemas florestais manejados, o caule das árvores representa o principal pool de carbono e que as perdas de carbono através das emissões respiratórias de CO2 tornam-se mais acentuadas nas árvores mais velhas, apenas em condições ambientais favoráveis ao ganho de carbono, tais como no outono, sendo influenciadas pelo turgor celular. Por outro lado, o acúmulo de carbono no solo parece estar relacionado com a relação entre as características intrínsecas do solo, sobretudo a granulometria, e a composição química das raízes, sobre os processos de estabilização da matéria orgânica no solo do que em relação à quantidade de serrapilheira depositada no solo.The continuous increase in the concentration of carbon dioxide in the atmosphere, due to the combustion of fossil fuels, changes in land use and deforestation for agriculture, is a matter of great importance due to its implications on global warming and climate change. Afforestation is seen as a solution to mitigate the increase in atmospheric CO2 concentration and may contribute to climate change mitigation through carbon sequestration in the trees’ biomass and soil. In this study we tried to assess some of the processes involving the carbon balance in forestry systems with eucalyptus. The study included field work to quantify the carbon stocks in the components forest system with trees of Eucalyptus saligna in the South of Brazil and the investigation of the effect of seasonal and ontogenetic variations on CO2 respiratory emissions from the leaves and stem of Eucalyptus globulus under the Mediterranean climate in central Portugal. The results of the Brazilian experiment showed that the stem biomass is the main pool of carbon in the forestry system (average 68% of total stock), followed by soil (30%) while the more labile carbon pools, such as leaf and root biomass and litter mass represent a smaller proportion of total carbon stock (2%). Clay and gravimetric water contents in the soil were associated with the observed variations in carbon storage in the soil and in the leaf and stem biomass. The accumulation of soil carbon was not directly associated with the production and chemical composition of the litter. However, the observed variations in carbon stock in the soil fractions (particulate and mineral organic carbon) were significantly associated with soil characteristics, especially the clay content, the concentration of copper and the chemical composition of roots. The observed relationships between soil characteristics and root fractions with the mineral and particulate organic carbon fractions seem to be associated with the function of the variables, cited above, on the processes of decomposition and stabilization of organic matter in soil. The results of the field experiment conducted in Portugal revealed that as the trees become larger and older, there is an increase in CO2 respiratory losses from leaves and stems. However, the marked increase in respiratory emissions observed in the older trees occurred only during the autumn, being associated with the recovery of plant water status after a period of drought during the summer. The increase in leaf and stem respiration of older trees after the recovery of cell turgor during the autumn seem to be related to increased energy costs in the processes of cellular maintenance rather than on growth respiration. The results of this study indicated that in managed forestry systems, the tree stem represents the major pool of carbon and carbon losses through the CO2 respiratory emissions become more pronounced in older trees, only under conditions favorable for carbon gain, such as in the autumn, being influenced by cell turgor. Moreover, the accumulation of carbon in the soil seems to be more related to the relationship between the intrinsic characteristics of the soil, particularly grain size and chemical composition of roots on the processes of stabilization of organic matter in the soil rather than the amount of litter deposited in soil.
5
Aggangan, Romulo T. "Effects of fertilization and previous land use on carbon and nutrient storage and dynamics in Eucalyptus globulus Labill. plantations in south-western Australia." Thesis, Aggangan, Romulo T. (1998) Effects of fertilization and previous land use on carbon and nutrient storage and dynamics in Eucalyptus globulus Labill. plantations in south-western Australia. PhD thesis, Murdoch University, 1998. https://researchrepository.murdoch.edu.au/id/eprint/52583/.
Full textAbstract:
In Western Australia, Eucalyptus globulus Labill. plantations are being established on land previously used for pasture, as well as on land recently cleared of the native forest vegetation. Little is known about the effects of previous land use and fertilizer treatments on soil fertility and nutrient cycling processes in E. globulus plantations established on these two contrasting sites. This thesis investigates the effects of fertilizer treatments (N, P or N-and-P) and previous land use on: (i) stores of carbon (C), nitrogen (N), phosphorus (P) and exchangeable cations in E. globulus plantations (Chapter 2); (ii) rates and amount of C and N mineralization (Chapter 3), (iii) changes in soil microbial biomass C and N (Chapter 5), and (iv) soil carbon fractions (Chapter 6). In addition, the influence of E. globulus leaf litter on C and N mineralization in soils from pasture and native forest is examined (Chapter 4) and the Carbon, Energy, Nutrients and Water (CenW) model is used to assess the effect of fertilizer and E. globulus leaf litter addition on soil N mineralization (Chapter 7).
Application of N-and-P fertilizer significantly increased the pools of C, N, P, and C:N ratio in soil under the E. globulus plantation established on an ex-native forest site. The pools of N and P were also enhanced by N-and-P fertilization in soil from the ex-pasture plantation site, but fertilization had no effect on the amount of total soil organic C or the C:N ratio. For the ex-native forest plantation soil, addition of N fertilizer decreased the pools of exchangeable Ca and Mg, whereas addition of P fertilizer reduced the pool of exchangeable Na. For the ex-pasture plantation soil, the pool of exchangeable K was significantly increased by P fertilization, whereas the pools of exchangeable Ca, Mg, and Na were not affected by N, P or N and P fertilization. The pools of C, N, P and exchangeable cations also varied among land uses suggesting that changes in these pools were related to previous land use.
Rates of microbial respiration and net N mineralization were measured using a long-term laboratory aerobic incubation (226 days at 20°C) in leaching microlysimeters. Potentially mineralizable N (N0) and net mineralization rate constant (k) were determined using a first-order kinetic model. For both ex-native forest and ex-pasture plantation soils, addition of N fertilizer markedly increased (about twofold) k, and reduced N0. Addition of P in the absence of N to the ex-native forest plantation soil reduced cumulative net N mineralization. The relative amounts of C02-C respired per unit of net N mineralized differed among the land use units. Amounts of net N mineralized (kg ha-1 in 0-200 mm soil) during the initial 28-day aerobic incubation period declined in the order: pasture (29), ex-pasture (18), ex-native forest (14), native forest (3), reflecting the low net N mineralization in native forest soil compared to managed systems.
The effects of E. globulus leaf litter on C and net N mineralization in pasture and native forest soils were evaluated using leaching microlysimeters. Cumulative net N mineralization declined in all treatments when litter was added, and was less when leaf litter was mixed with soil. Cumulative C02-C respired increased with the increasing rate of leaf litter addition, both when leaf litter was mixed through the soil and placed on the soil surface. These increases were associated with increases in microbial biomass C content of soil.
Changes in microbial biomass C and N were evaluated in soils under the E. globulus plantations that were fertilized with either N, P or N-and-P and at different seasons using the chloroform fumigation-extraction method. In the two plantation soils, microbial biomass C and N were at maximum levels in spring and minimum levels in summer. Addition of P or N-and-P fertilizer reduced the microbial biomass N concentration in the ex-native forest plantation soil, and addition of N and N-and-P fertilizer reduced the microbial biomass N in the ex-pasture plantation soil. Microbial biomass C concentration (kg ha-1 in 0-200 mm soil depth) declined in the order: native forest soil (1018), pasture soil (944), ex-native forest plantation soil (600), and ex-pasture plantation soil (591), whereas microbial biomass N concentration declined in the order: pasture soil (152), native forest (109), ex-native forest soil (84), and ex-pasture soil (83).
The soil C fractions were measured using a fractionation procedure based on ease of oxidation with 333 mM potassium permanganate. Soils from adjacent native forest and pasture were sampled and analysed for C fractions. In the ex-native forest plantation soil, the amount of total soil organic carbon (CT), labile carbon (CL) and non-labile carbon (CNL) were not affected by addition of either N or P, but were significantly increased by application of N-and-P fertilizer. The carbon pool index (CPI) which reflects changes in the amount of total soil C in fertilized plots relative to the control treatment, and carbon management index (CMI) which relates changes in CPI and the proportion of labile and non-labile soil C to fertilizer treatments also increased significantly with combined application of N-and-P. By contrast, in the ex-pasture plantation soil, fertilizer amendment had no effect on CT, CL CNL, CPI or CMI. Further, the soil C fractions show that the conversion of native forest or pasture to E. globulus plantations has resulted in losses of C relative to the reference soils. This is also reflected in the CPI and CMI, suggesting that eucalypt plantations are likely to result in relative losses of soil C.
Rates of N mineralization were predicted using the CenW model and outputs were validated using measured net N mineralized in aerobic laboratory incubations. The CENW model adequately predicted the rates of N mineralization in both the ex-native forest and ex-pasture plantation soils either using long or short-term aerobic laboratory incubations. There was also good agreement between observed and simulated rates of N mineralization when E. globulus leaf litter was added to soil at different rates.
In conclusion, the results of these studies show that previous land use and fertilizer treatments had significant influence on the organic matter status of the soil. Moreover, the rate of net N mineralization in both plantation soils differed markedly and these were associated with previous land use. Hence, management strategies to maintain soil fertility and sustainability of the E. globulus plantations must consider past land use and fertilizer history.
6
BOIFFIN, VINCENT. "Contribution a l'etude de la regulation du metabolisme carbone de l'ectomycorhize d'eucalyptus globulus-pisolithus tinctorius. Caracterisation, clonage et expression de l'isocitrate deshydrogenase a nadp de la racine." Paris 11, 1997. http://www.theses.fr/1997PA112408.
Full textAbstract:
L'analyse rmn de l'assimilation du 1-#1#3c glucose dans l'ectomycorhize d'eucalyptus globulus-pisolithus tinctorius montre que les teneurs en composes carbones (acides amines et sucres) de la racine et du mycelium sont modifiees par rapport aux partenaires non-associes. Le flux de c (via le cycle de krebs) approvisionne de maniere consequente la synthese de glutamine. Le marquage intramoleculaire de la glutamine fait ressortir l'importance de la fixation anaplerotique du co#2. Ces etudes de marquage isotopique revelent l'interet de l'etude des enzymes a l'interconnexion entre les metabolismes n et c et leur co-regulation dans l'ectomycorhize. La phosphoenolpyruvate carboxylase (pepc) est impliquee dans la fixation anaplerotique du co#2. Cet enzyme est stimule trois fois dans l'ectomycorhize sans augmentation de la concentration du polypeptide, ni variation de l'etat de phosphorylation de l'enzyme. L'isocitrate deshydrogenase a nadp (icdh a nadp) cytosolique fournit l'alpha-cetoglutarate utilise pour l'assimilation de l'azote. L'activite de l'enzyme est stimulee 2,5 fois dans l'ectomycorhize mais sa localisation tissulaire preponderante dans les tissus conducteurs et dans l'epiderme n'est pas modifiee. Afin d'etudier les mecanismes moleculaires impliquees dans la biosynthese de l'icdh a nadp, un adnc pleine longueur (egicdh) a ete clone. L'accumulation des transcrits egicdh est augmentee deux fois dans les ectomycorhizes agees de 2 et 4 jours. La glutamine synthetase (gs) est l'enzyme-clef de l'assimilation de l'ammonium. Avec un fragment d'adnc codant pour une sous-unite de la gs cytosolique (eggs), le niveau de transcrits eggs a ete suivi au cours de la formation de l'ectomycorhize. L'expression du gene eggs est reprimee dans les ectomycorhizes agees de 2 jours. A des stades plus tardifs, elle revient a un niveau comparable de celui de la racine non-inoculee.
7
Forrester, David Ian, and davidif@unimelb edu au. "Mixed-species plantations of nitrogen-fixing and non-nitrogen-fixing trees." The Australian National University. Faculty of Science, 2005. http://thesis.anu.edu.au./public/adt-ANU20050202.164252.
Full textAbstract:
Mixed-species plantations of eucalypts and acacias have the potential to improve stand productivity over that of respective monocultures through the facilitative effect of nitrogen-fixation by acacias, and increased resource capture through above- and belowground stratification. However, growth in mixed-species plantations may not be improved compared to that of monocultures when competitive interactions outweigh the effects of improved nutrient availability and resource capture. Careful selection of sites and species is therefore critical to successfully improving stand productivity using mixed-species plantations. This study set out to examine some of the processes and interactions that occur in mixed-species plantations, and the effect nutrient and water availability can have on the growth of mixtures.
In three out of four mixed-species field trials examined in this study, growth was not increased in mixtures compared to monocultures. However, in the fourth field trial, heights, diameters, stand volume and aboveground biomass were higher in mixtures of E. globulus and A. mearnsii from 3-4 years after planting.
The range in outcomes from mixing species in these four trials shows that a fundamental understanding of the underlying processes is required to enable a greater predictive capacity for the circumstances under which mixtures will be successful. Therefore the growth dynamics, processes and interactions were examined in the mixtures of E. globulus and A. mearnsii. The difference in productivity between mixtures and monocultures in this trial increased with time up to age 11 years, when 1:1 mixtures contained twice the aboveground biomass of E. globulus monocultures. The positive growth response of trees in mixture compared to monocultures was the result of accelerated rates of nutrient cycling, a shift in C allocation and reductions in light competition through canopy stratification.
Nitrogen contents of foliage and soil clearly showed that A. mearnsii influenced the N dynamics in this trial. If these changes in N contents were due to N fixation by A. mearnsii, then about 51 and 86 kg N ha-1 yr-1 was fixed in the 1:1 mixtures and A. mearnsii monocultures, respectively. Nitrogen fixation was also examined using the natural abundance method. The delta15N values of foliage collected at 10 years were grouped according to the mycorrhizal status of the host plant. Therefore the discrimination of 15N during transfer from mycorrhizae to the host plant appeared to vary with mycorrhizal status, and the natural abundance of 15N was not used to quantify N fixation.
Rates of N and P cycling in litterfall were significantly higher in stands containing at least 25% A. mearnsii (more than 31 kg N ha-1 yr-1 and more than 0.68 kg P ha-1 yr-1) compared to E. globulus monocultures (24 kg N ha-1 yr-1 and 0.45 kg P ha-1 yr-1). Rates of litter decomposition and N and P release were about twice as high in 1:1 mixtures compared to E. globulus monocultures and were even higher in A. mearnsii monocultures. It is therefore important to select N-fixing species that are capable of cycling nutrients quickly between the plant and soil, and that have readily decomposable litter.
The total belowground C allocation was not significantly different between mixtures and monocultures (14 to 16 Mg C ha-1 yr-1). However, since aboveground net primary production was greater in 1:1 mixtures, the changes in nutrient availability appears to have increased total productivity (both above- and belowground), and reduced the proportion of C allocated belowground in mixtures compared to E. globulus monocultures.
In a pot trial containing mixtures of E. globulus and A. mearnsii both species grew larger in mixture than in monoculture at low N levels, and mixtures were more productive than monocultures. However, at high N levels, E. globulus suppressed A. mearnsii and mixtures were less productive than E. globulus monocultures. Similar effects were found for high and low levels of P.
Therefore resource availability can have a strong influence on the interactions and growth of mixtures. The productivity of mixtures may only be increased on sites where the resource for which competition is reduced in mixture is a major limiting growth resource. For example, if N is not a limiting growth factor then an increase in N availability from N-fixation may not increase growth, and the N-fixing species may compete for other resources such as soil P, moisture or light.
This study has shown that mixtures containing a N-fixing trees and a non-N-fixing trees can be more productive than monocultures, but that this increase in productivity will only occur on certain sites. Examination of the growth, interactions and processes that occurred in mixtures in this study provide useful information that can aid the selection of species combinations and sites.
8
Kumar, Rajeev. "Synthesis and development of multifunctional carbonaceous nanostructures for magnetic, optical and catalytic applications." Thesis, 2019. https://etd.iisc.ac.in/handle/2005/4951.
Full textAbstract:
Owing to the ease of functionalization, low synthesis-cost and polymorphism,
carbonaceous nanostructures such as carbon globules, nanotubes (CNTs) and graphene sheets
emerged technologically as one of the most important class of multifunctional materials. In this
thesis a wide variety of carbon based nanostructures were synthesized by the simple pyrolysis
method, characterized and their applicabilities are demonstrated. Among the synthesized
materials, metallic particles embedded amorphous carbon globules, CNTs of different
morphologies such as spiralling tendrils, cup and box type bamboos, hollow and filled onions
etc. are the exotic ones. We also demonstrated a way to synthesize nanoscale particles of various
metallic alloys, which can be useful for any structural design in powder metallurgy. These
carbon coated metallic particles, which protect themselves against any environmental corrosion,
are otherwise, difficult to synthesize by any other conventional method. The structure,
morphology, size distribution of the dispersed metallic particles in carbon nanostructures were
investigated and correlated with their optical, magnetic, electronic and chemical properties.
We have demonstrated multifunctionality of our synthesized carbonaceous materials. Our
investigation highlights the non-linear absorption of laser beams in metallic nanoparticles
embedded carbon materials, making them potential candidates for optical limiters. Furthermore,
the dispersion of nano-sized metallic particles inside amorphous carbon matrix proves to be
microwave absorption enhancers, enabling their use as electromagnetic interference (EMI)
shields. In addition, the catalytic activity of most of our samples is excellent, but can be further
improved by controlling the amount of defects via nitrogen doping. The catalytic performance
for reduction of 4-nitrophenol by some selective samples exceeds many of the catalysts reported
earlier. The performance of some of our samples in electronic devices such as in infrared photodetectors
is exceptional. The use of the samples for magnetorheological applications for energy storage
and many other applications cannot be undermined. Hence, our work demonstrates that
our synthesized samples are versatile and truly multifunctional
9
Lai, Szu-Yu, and 賴思妤. "The Application of Using Carbon Nanocomposite and Biosynthesis of Silver Nanoparticles with Eucalyptus globulus." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/rnj46s.
Full textAbstract:
碩士國立臺北科技大學
化學工程研究所
102
Part 1 Hybridization of poly(luminol) (PLM) and poly(neutral red) (PNR) has been successfully performed and further enhanced by a conductive and steric hybrid nanotemplate using graphene oxide (GO) and multi-walled carbon nanotubes (MWCNT). Morphology of PLM-PNR-MWCNT-GO mycelium-like nanocomposite is studied by SEM and AFM and it is electroactive, pH-dependent, and stable in the electrochemical system. It shows eletrocatalytic activity to NADH with high current response and low overpotential. By amperometry, it shows a high sensitivity of 288.9 μA mM-1 cm-2 to NADH (Eapp. = +0.1 V). Linearity is estimated in a concentration range of 1.33×10-8 – 1.95×10-4 M with a detection limit of 1.33×10-8 M (S/N = 3). Particularly, it also shows another linear range of 2.08×10-4 – 5.81×10-4 M with a sensitivity of 151.3 μA mM-1 cm-2. Hybridization and activity of PLM and PNR can be effectively enhanced by MWCNT and GO, performing an active hybrid nanocomposite for determination of NADH. Part 2 This study presents a simple electrochemical approach for preparing the graphene oxide (GO)/multiwalled carbon nanotubes (MWCNTs) composite by homogenous dispersion of MWCNTs and GO, which responds sensitively for the electrochemical determination of pyrazinamide (PZM). The surface morphological results by transmission electron microscope (TEM) confirmed that MWCNTs were wrapped with GO sheets. The MWCNTs/GO composite showed superior electrocatalytic activity towards the reduction of PZM when compared with either pristine MWCNTs or GO. The major reason for the efficient simultaneous detection at nanocomposite was the synergistic effect between MWCNTs and GO. The electrochemical reduction of PZM was investigated by cyclic voltammetry and differential pulse voltammetry. The response of PZM is linear over the concentration range from 37.5 – 1800 μM, with the detection limit (S/N = 3) of 5.54 μM and the sensitivity was found to be 38 μA mM -1 cm -2. The proposed sensor exhibits good sensitivity, selectivity and has shown potential for the detection of PZM in real samples with appreciable consistency and precision. In addition, the proposed electrochemical sensor showed good results towards the commercial pharmaceutical formulated PZM samples. Part 3 The preparation of nanostructured metal particles provides an environmentally friendly option, as compared to currently available chemical and/or physical methods. Here we have biosynthesized silver nanoparticles (AgNPs) from plant extracts. In this work, a single-step low-temperature biosynthetic route for producing AgNPs using Eucalyptus (Eucalyptus globulus) extract. Stable AgNPs were formed by treating solution using the plant extracts as reducing agents. These nanoparticles were analyzed by various characterization techniques to reveal their morphology, chemical composition, and bioactivity. Nanostructure size, crystal nature, purity and morphologies were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), Gas chromatography–mass spectrometry (GC/MS), X-ray diffraction (XRD) and Cyclic voltammetry (CVs). The particle size ranging from 100 to 500 nm and the shape of the plate and spherical structures could be controlled by changing the reaction temperature and leaf broth concentration. The concentrations of leaves extract and metal ion are playing an important role in the biosynthesis of AgNPs. More elaborate studies are required to elucidate the mechanism of biological nanoparticles synthesis. This simple, low cost and greener method for development of AgNPs may be valuable in environmental, biotechnological and biomedical applications.
10
Forrester, David Ian. "Mixed-species plantations of nitrogen-fixing and non-nitrogen-fixing trees." Phd thesis, 2004. http://hdl.handle.net/1885/46988.
Full textAbstract:
Mixed-species plantations of eucalypts and acacias have the potential to improve stand productivity over that of respective monocultures through the facilitative effect of nitrogen-fixation by acacias, and increased resource capture through above- and belowground stratification. However, growth in mixed-species plantations may not be improved compared to that of monocultures when competitive interactions outweigh the effects of improved nutrient availability and resource capture. Careful selection of sites and species is therefore critical to successfully improving stand productivity using mixed-species plantations. This study set out to examine some of the processes and interactions that occur in mixed-species plantations, and the effect nutrient and water availability can have on the growth of mixtures.
¶
In three out of four mixed-species field trials examined in this study, growth was not increased in mixtures compared to monocultures. However, in the fourth field trial, heights, diameters, stand volume and aboveground biomass were higher in mixtures of E. globulus and A. mearnsii from 3-4 years after planting.
¶ ...
Books on the topic "Carbon globules"
1
Laureno, Robert. Selective Vulnerability. Edited by Robert Laureno. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190607166.003.0006.
Full textAbstract:
This chapter on “Selective Vulnerability” examines the selective vulnerability of different parts of the brain to particular diseases. In one disease, certain areas of brain are particularly vulnerable. In other diseases, different parts of the brain are more susceptible. The concept of selective vulnerability was originally applied to toxic/metabolic and hereditary disorders, but it is also useful in thinking about other neuropathologic processes including neoplastic, infectious, demyelinative, vascular, and traumatic diseases. Diseases can selectively affect brain systems, brain structures, or brain regions. Selective system involvement is clear in degenerative diseases such as amyotrophic lateral sclerosis; selective structure involvement occurs in carbon monoxide’s effect on the globus pallidus; selective region involvement is found in myelinolysis.
Book chapters on the topic "Carbon globules"
1
Kedir, Miftah F. "Pyrolysis Bio-oil and Bio-char Production from Firewood Tree Species for Energy and Carbon Storage in Rural Wooden Houses of Southern Ethiopia." In African Handbook of Climate Change Adaptation, 1313–29. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_183.
Full textAbstract:
AbstractThe need for emission reduction for climate management had triggered the application of pyrolysis technology on firewood that yield bio-oil, bio-char, and syngas. The purpose of present study was to select the best bio-oil and bio-char producing plants from 17 firewood tree species and to quantify the amount of carbon storage. A dried and 1 mm sieved sample of 150 g biomass of each species was pyrolyzed in assembled setup of tubular furnace using standard laboratory techniques. The bio-oil and bio-char yields were 21.1–42.87% (w/w) and 23.23–36.40% (w/w), respectively. The bio-oil yield of Acacia seyal, Dodonea angustifolia, Euclea schimperi, Eucalyptus globulus, Casuarina equisetifolia, and Grevillea robusta were over 36% (w/w), which make the total yield of bio-oil and bio-char over 62% (w/w) of the biomass samples instead of the 12% conversion efficiency in traditional carbonization. The calorific value of firewood was 16.31–19.66 MJ kg–1 and bio-oil was 23.3–33.37 MJ kg–1. The use of bio-oil for household energy and bio-char for carbon storage reduced end use emission by 71.48–118.06%, which could increase adaptation to climate change in comparison to open stove firewood by using clean fuel and reducing indoor pollution.
2
Barbuy, B., A. Milone, M. Spite, and F. Spite. "Carbon and Nitrogen in the Cool Supergiant A7 of the Young Globular Cluster NGC 330 in the SMC." In The Magellanic Clouds, 370–71. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3432-3_95.
Full text
3
Li, Ni, Gengbiao Zhang, Hongyi Zheng, Weijia Li, and Wenbin Zheng. "Diffusion Kurtosis Imaging Detects Microstructural Changes in the Brain After Acute Carbon Monoxide Intoxication in Rats." In Computer Methods in Medicine and Health Care. IOS Press, 2022. http://dx.doi.org/10.3233/atde220539.
Full textAbstract:
The aim of this study is exploring the value of diffusional kurtosis imaging (DKI) in the diagnosis of acute carbon monoxide poisoning encephalopathy in vivo rats. Forty healthy male Sprague-Dawley rats, were divided into a control group and CO poisoning model group. DKI during 7.0 T MR were performed in the globus pallidus, hippocampus and parietal cortex in the rats. During acute CO poisoning, compared with controls, Mean kurtosis values (MK) and Mean diffusivity (MD) values were significantly decreased both in the hippocampus and parietal cortex, however, in the globus pallidus were significantly increased.The pathological findings showed emerged granular cytoplasmic changes, thickening of chromatin of the neurons, and local lymphocytic infiltration. However, the condition in the hippocampus and parietal cortex was significantly milder than in the globus pallidus region in the first day or 3 days later. Both Immunohistochemical analysis of the heme oxygenase-1 of rats and MK values increased only in globus pallidus with a statistical difference between the CO poisoning group and the normal group both in the day 1 and day 3. DKI can possess sufficient sensitivity for tracking pathophysiological changes associated with carbon monoxide intoxication. The higher MK values in acute stage of carbon monoxide intoxication might indicate poor prognosis in the evolution of the condition.
4
Rano, Ruma. "Characterization of Magnetic and Non-Magnetic Components From a Low Carbon Fly Ash." In Global Perspectives on Air Pollution Prevention and Control System Design, 46–67. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7289-3.ch002.
Full textAbstract:
Low carbon coal ash—a solid air pollutant from super thermal power plant using pulverized fuel combustor—has been characterized in respect of its physico-chemical, mineralogical, and morphological features. Size-classified fractions with their magnetic and non-magnetic components have also been characterized. Low loss on ignition and particle size distribution profile shows fly ash has high utility. The magic number,10 µm, is attained by greater % of particles. The particles with diameter 50 µm occupy population density of 93%. SEM-EDS reveals that particles are mostly globular with high surface enrichment of Al/Si indicating that it will act as un-reactive inert fillers. In magnetic components, various types of Fe bearing phase are present with less porous and more regular shape than non-magnetic components. Finer fractions have high content of magnetite which is expected to help in coal beneficiation. The finer non-magnetic fraction is a source of alumino-siliceous material for synthesizing a novel solid acid or base catalyst for catalyzing industrially important organic reactions.
Conference papers on the topic "Carbon globules"
1
Sadhanala, Hari Krishna, and Karuna Kar Nanda. "Air stable iron/iron carbide magnetic nanoparticles embedded in amorphous carbon globules." In NANOFORUM 2014. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4918247.
Full text
2
Menzies, John. "A Carbon-rich Mira variable in a globular cluster: A stellar merger." In SALT Science Conference 2015. Trieste, Italy: Sissa Medialab, 2016. http://dx.doi.org/10.22323/1.250.0005.
Full text
3
Kim, Sungwon S., Tom T. Huang, Timothy S. Fisher, and Michael R. Ladisch. "Effects of Carbon Nanotube Structure on Protein Adsorption." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81395.
Full textAbstract:
Outstanding transport characteristics and high surface-to-volume ratios are several advantages that carbon nanotubes possess that make them attractive candidates for protein immobilization matrices in biosensor applications. A further advantage of using carbon nanotubes is that their structure (e.g., diameter, length, density) can potentially be controlled during synthesis. In the present study, the effects of carbon nanotube structure on enzyme immobilization onto carbon nanotube arrays are investigated. Bovine serum albumin (BSA) serves as both a blocking agent for prevention of nonspecific adsorption and as a support for anchoring bioreceptors. BSA, a globular protein having a 4 to 6 nm characteristic dimension, is stably adsorbed through mechanisms that involve hydrophobic interactions between surfaces presented by the carbon nanotubes and the spacing between the nanotubes with the protein. Protein adsorption is confirmed by fluorescence microscopy of surfaces that have been exposed to fluourescein isothiocyanate (FITC) labeled BSA. The adsorption of biotinylated BSA can be used, through a sandwich immobilization scheme, to provide an anchor for streptavidin, which in turn has at least one other adsorption site that is specific for other biotinylated proteins such as glucose oxidase that would form a biorecognition or catalytic element in a functional biosensor. Correlation between carbon nanotube structure and protein adsorption at the nano-bio interface could eventually lead to growth conditions that yield carbon nanotubes for biosensor applications with optimal protein adsorption characteristics.
4
Liebeherr, M., N. Bernier, D. Le`bre, N. Ilic´, and D. Quidort. "Microstructure–Property Relationship in 22mm Thick X80 Coil Skelp." In 2010 8th International Pipeline Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ipc2010-31250.
Full textAbstract:
The progress in the development of heavy gauge X80 linepipe steel on coil at ArcelorMittal was recently rewarded with a 6000 ton commercial order for the production of 21.6mm wall thickness spiral welded pipe. The further product development is concentrating on the improvement of the impact toughness at low temperatures. Research is currently focussing on the relationship between the mechanical properties and the microstructure of the steels. In the present study, two industrially hot rolled X80 steels with thickness 21.6mm were investigated. The steels had the same chemical composition but were processed with different parameter sets in the hot strip mill. The two resulting low-carbon bainitic microstructures were composed predominantly of quasi-polygonal ferrite and globular bainitic ferrite / bainitic ferrite, respectively. Emphasis of the microstructure and property characterisation was laid on through-thickness gradients of grain size, hardness, texture, impact toughness and tensile properties. Accordingly, the materials were characterised at different positions in the thickness. Grain size and texture were determined by means of Electron Backscatter Diffraction (EBSD). Sub-size Charpy as well as sub-thickness tensile test specimens were taken at different positions in the cross section. The results show that the link between microstructure and properties is not at all obvious. The influence of mean grain size, grain size distribution and texture is discussed in detail.
5
Silber, M., E. Dongmo, R. Gadow, and M. Wenzelburger. "Thermal Spraying as a Manufacturing Technology for Light Metal MMC; Experimental and Numerical Process Analysis." In ITSC2008, edited by B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima, and G. Montavon. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2008. http://dx.doi.org/10.31399/asm.cp.itsc2008p0894.
Full textAbstract:
Abstract For the manufacturing of metal matrix composites, a combined process of thermal spraying followed by forging in the semi-solid state can be applied. In previous work, it has been shown that thermal spraying leads to a globular microstructure that is suitable for semi-solid forming. Thereby, penetration of the spray material into the reinforcement phase leads to reduced matrix flow paths and thus reduced forming time and fiber disarrangement during the forming process. The main requirement is a low substrate and coating temperature during matrix deposition. By control of the process temperature, geometrical accuracy of the prepreg material and it’s handling between each process step can be significantly improved, leading to an economical method that is a superior alternative to the well established MMC processes like diffusion bonding or squeeze casting. Moreover, due to low process temperatures and process time during matrix application, chemical attack of carbon fiber reinforcements can be reduced. Process development for the manufacturing of continuous fiber reinforced prepregs was focused on the analysis and control of particle properties and substrate temperature. In order to improve the temperature control during arc wire spraying, numerical process analysis of the cooling system was applied. Particle in-flight analysis with the SprayWatch system was used to obtain direct spray parameters as input data for the numerical models. The simulation results were verified by experimental infrared thermography of the substrate during coating. By the use of an optimized cooling system, dense coatings without cracks were achieved with different coating thickness, thereby tailoring the fiber volume content of the final MMC component.
6
Oliveira, Daniel Alves de, Vitor Maia Arca, Arthur Cesário de Holanda, Luziany Carvalho Araújo, Bruno Henrique Carneiro Costa Filho, Letícia Klabinske Marques Monteiro, Evelliny Gomes da Silva, and Marcos Eugênio Ramalho Bezerra. "Bilateral pallido-nigral lesions in a patient with subacute chorea after diabetic ketoacidosis: case-report." In XIV Congresso Paulista de Neurologia. Zeppelini Editorial e Comunicação, 2023. http://dx.doi.org/10.5327/1516-3180.141s1.778.
Full textAbstract:
Case presentation: A 54-year-old female patient, with prior history of arterial hypertension and type 2 diabetes, presented a one-year history of bilateral weakness in lower limbs, cognitive impairment and irregular hyperkinectic movements in upper limbs and face. The clinical onset was subacute after hospitalization due to severe pneumonia and diabetic ketoacidosis, which required intensive care unit care and ventilatory assistance for more than 15 days. On physical examination, she presented cognitive impairment with dysexecutive predominance, spastic paraparesis and facial and upper limbs chorea, mainly on the left side. Laboratory findings included a vitamin B12 level of 184 pg/mL. Brain magnetic resonance imaging revealed marked hypointensities in the globus pallidus and mesencephalic substantia nigra bilaterally, besides global encephalic atrophy and nonspecific white matter hyperintensities. Patient improved of chorea with administration of risperidone. Discussion: Toxic and metabolic lesions can involve the basal ganglia symmetrically, due to the high rate of metabolism and oxygenation required by these structures. The most common etiology of bilateral pallidal lesions are poisoning by carbon monoxide and cyanide intoxication. In this case, diabetic ketoacidosis was observed as a possible precipitating factor for the pallidonigral lesions, which is an uncommon association for this type of injury. Conclusion: Patients with acute and subacute movement disorders should be extensively investigated for injuries in basal ganglia associated to hypoxic or metabolic etiologies.