Vibrational Analysis Of Amorphous Carbon-nitrogen Alloys By 15n And D Isotopic Substitution

The origin of the vibrational modes of a-CNx alloys is investigated by infrared (ir) and Raman spectroscopies. Isotopic substitution of 15N and D is used in the identification of vibration modes. In nonhydrogenated materials containing low nitrogen concentration (≤20 at. %), the ir and Raman spectra are not equivalent. Above this concentration (up to ∼30 at. %), the spectra became very similar to each other. On the contrary, for a suitable hydrogen content the spectra are quite similar, independently of the range of nitrogen concentrations studied. Quantum chemical Parametric Method 3 calculations are performed to obtain the frequencies and intensities of the ir active vibrations of organic molecules and large carbon-nitrogen clusters. These results are used to help in the identification of the features observed in the ir spectra. The importance of both the promotion of bond dipoles and symmetry breaking by nitrogen in the ir spectra is established. ©2000 The American Physical Society.61210831087Fang, P.H., (1995) J. Mater. Sci. Lett., 14, p. 536Franceschini, D.F., Achete, C.A., Freire Jr., F.I., (1992) Appl. Phys. Lett., 60, p. 3229Jones, D.I., Stewart, A.D., (1982) Philos. Mag. B, 46, p. 423Chen, L.C., Lu, T.R., Cuo, C.T., Bhusari, D.M., Wu, J.J., Chen, K.H., Chen, T.M., (1998) Appl. Phys. Lett., 72, p. 3449Liu, A., Cohen, L., (1989) Science, 245, p. 841Kaufman, J.H., Metin, S., Saperstein, D.D., (1989) Phys. Rev. B, 39, p. 13053Souto, S., Alvarez, F., (1997) Appl. Phys. Lett., 70, p. 1539Hammer, P., Victoria, N.M., Alvarez, F., (1998) J. Vac. Sci. Technol. A, 16, p. 2941Alvarez, F., Victoria, N.M., Hammer, P., Freire Jr., F.L., Dos Santos, M.C., (1998) Appl. Phys. Lett., 73, p. 1065Alvarez, F., Dos Santos, M.C., Hammer, P., (1998) Appl. Phys. Lett., 73, p. 3521Souto, S., Pickholz, M., Dos Santos, M.C., Alvarez, F., (1998) Phys. Rev. B, 57, p. 2536Dos Santos, M.C., Alvarez, F., (1998) Phys. Rev. B, 58, p. 13918Stewart, J.J.P., (1989) J. Comput. Chem., 10, p. 209(1995) SPARTAN, Package V. 5, , Wavefunction, Inc(1996) HYPERCHEM, Version 5, , Hypercube, IncLey, L., (1984) Topics in Applied Physics, 56. , The Physics of Hydrogenated Amorphous Silicon II, edited by J. D. Joannopoulos and G. Lucousky, Springer-Verlag, BerlinSubramanian, V., Chitra, K., Venkatesh, K., Sanker, S., Ramasami, T., (1997) Chem. Phys. Lett., 264, p. 92Shinohara, Y., Saito, R., Kimura, T., Dresselhaus, G., Dresselhaus, M.S., (1994) Chem. Phys. Lett., 227, p. 365Borisenko, V.E., Baturin, A.V., Przeslawka, M., Koll, A., (1997) J. Mol. Struct., 407, p. 53Robertson, J., (1991) Prog. Solid State Chem., 21, p. 19

Use of floating PV plants for coordinated operation with hydropower plants: Case study of the hydroelectric plants of the Sao Francisco River basin

[EN] In recent years, the Brazilian electricity sector has seen a considerable reduction in hydroelectric production and an increase in dependence on the complementation of thermoelectric power plants to meet the energy demand. This issue has led to an increase in greenhouse gas emissions, which has intensified climate change and modified rainfall regimes in several regions of the country, as well as increased the cost of energy. The use of floating PV plants in coordinated operation with hydroelectric plants can establish a mutual compensation between these sources and replace a large portion of the energy that comes from thermal sources, thereby reducing the dependence on thermoelectric energy for hydropower complementation. Thus, this paper presents a procedure for technically and economically sizing floating PV plants for coordinated operation with hydroelectric plants. A case study focused on the hydroelectric plants of the Sao Francisco River basin, where there has been intense droughts and increased dependence on thermoelectric energy for hydropower complementation. The results of the optimized design show that a PV panel tilt of approximately 3 degrees can generate energy at the lowest cost (from R $298.00/MWh to R$312.00/MWh, depending on the geographical location of the FLOATING PV platform on the reservoir). From an energy perspective, the average energy gain generated by the hydroelectric plant after adding the floating PV generation was 76%, whereas the capacity factor increased by 17.3% on average. In terms of equivalent inflow, the PV source has a seasonal profile that compliments the natural inflow of the river. Overall, the proposed coordinated operation could replace much of the thermoelectric generation in Brazil.The authors would like to thank the Brazilian National Council for Scientific and Technological Development (Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq; in Portuguese) for granting a productivity in research scholarship to Prof. Regina Mambeli Barros (PQ2, Process number: 301986/2015-0) and Prof. Geraldo Lúcio Tiago Filho and to the Brazilian Coordination for the Improvement of Higher Education Personnel (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Capes; in Portuguese) for granting the Master of Science scholarship to Naidion Motta Silvério and the Doctorate scholarship to Ivan Felipe da Silva dos Santos.Silverio, N.; Barros, R.; Tiago Filho, GL.; Redón-Santafé, M.; Silva Dos Santos, IF.; De Mello Valerio, VE. (2018). Use of floating PV plants for coordinated operation with hydropower plants: Case study of the hydroelectric plants of the Sao Francisco River basin. Energy Conversion and Management. 171:339-349. https://doi.org/10.1016/j.enconman.2018.05.095S33934917

Uso Do 1-mcp E Atmosfera Modificada Na Pós-colheita De Atemoia 'gefner'

The scarcity of technologies related to the post-harvest physiology of this species is one of the barriers to commercialization of atemoya over long distances, aggravated by perishability presented by them. Thus, the objective of this study was to prolong the shelf life of atemoya fruits using 1-methylcyclopropene (1-MCP) and modified atmosphere by low-density polyethylene (LDP), associated with refrigeration. The experiment was conducted in a completely randomized design in a split-plot, with plots in the four doses of 1-MCP (0, 200, 400 and 600 ?L L-1), and in the 5 subplots evaluation periods after harvest in the range of 5 days, with four replicate. Atemoyas were harvested at physiological maturity then treated with doses of 1-MCP for 8 h at room temperature. Soon after, the fruits were placed in polystyrene trays. Some remained unpacked and others were packed with a plastic film of LDP 16 μm. The use of modified atmosphere and 1-MCP alone or combined, were effective in delaying the ripening of fruits, allowing the preservation of its chemistry quality. In the fruits treated with 1-MCP was no delay in the accumulation of soluble solids and starch degradation.112677

Directly converted astrocytes retain the ageing features of the donor fibroblasts and elucidate the astrocytic contribution to human CNS health and disease

Astrocytes are highly specialised cells, responsible for CNS homeostasis and neuronal activity. Lack of human in vitro systems able to recapitulate the functional changes affecting astrocytes during ageing represents a major limitation to studying mechanisms and potential therapies aiming to preserve neuronal health. Here, we show that induced astrocytes from fibroblasts donors in their childhood or adulthood display age‐related transcriptional differences and functionally diverge in a spectrum of age‐associated features, such as altered nuclear compartmentalisation, nucleocytoplasmic shuttling properties, oxidative stress response and DNA damage response. Remarkably, we also show an age‐related differential response of induced neural progenitor cells derived astrocytes (iNPC‐As) in their ability to support neurons in co‐culture upon pro‐inflammatory stimuli. These results show that iNPC‐As are a renewable, readily available resource of human glia that retain the age‐related features of the donor fibroblasts, making them a unique and valuable model to interrogate human astrocyte function over time in human CNS health and disease