Field-emission Properties Of Sulphur Doped Nanocrystalline Diamonds

Nanostructured diamond doped with sulphur has been prepared using a hot-filament assisted chemical vapour deposition system fed with an ethyl alcohol, carbon disulfide, hydrogen, and argon mixture. The reduction of diamond grains to the nanoscale is relevant to create a network of defective grain boundaries which may be n-type doped to facilitate the transport and injection of electrons to the diamond grains located at the vacuum interface, enhancing the electron field-emission properties of the samples. The downsizing was produced by secondary nucleation and defects induced by sulphur and argon atoms in the chemical vapour deposition surface reactions. Sulphur also acts as an n-type dopant of diamond. Raman measurements show that the samples are nanodiamonds embedded in a matrix of graphite and disordered carbon grains and the morphology, revealed by field electron scanning microscopy, shows that the grains are in the range of 10 to 30 nm. The lowest threshold achieved for field emission was 13.20 V/μm. © 2007 IOP Publishing Ltd.6116670Yang, A.T.S., Lay, J.Y., Wong, M.S., Cheng, C.L., (2002) J. Appl. Phys., 92 (4), p. 2133Mammana, V.P., Tea, S., Mammana, A., Baranauskas, V., Ceragioli, H.J., Peterlevitz, A.C., (2002) Appl. Phys. Lett., 81 (18), p. 3470Baranauskas, V., Fontana, M., Ceragioli, H.J., Peterlevitz, A.C., (2004) Nanotech., 15 (10), p. 678Gruen, D.M., (1998) MRS Bull., 9, p. 32Jin, B.M., Kim, C.C., (1997) Appl. Phys. A: Solid Surf., 65 (1), p. 53Himpsel, F.J., Knapp, J.A., Vanvechten, J.A., Eastman, P.E., (1979) Phys. Rev., 20 (2), p. 624Bandis, B., Pate, B.B., (1996) Appl. Phys Lett., 69 (3), p. 366Okano, K., Yamada, T., Suave, A., Koizumi, S., Pate, B.B., (1999) Appl. Surf. Sci., 146 (1-4), p. 274Kurt Bonard, R.J.M., Karimi, A., (2001) Diam. Rel. Mater., 10 (11), p. 1962Bonnot, A.M., Deldem, M., Beaugnon, M., Fournier T.schouler, M.C., Mermoux, M., (1999) Diam. Rel. Mater., 8 (2-5), p. 631Gruen, D.M., Liu, S., Krauss, A.R., Liuy, A., Luo, J., Foster, C.M., (1994) J. Vac. Sci. Technol., 12 (4), p. 1491Gupta Weiner, S.B.R., Morell, G., (2002) Diam. Rel. Mater., 11 (3-6), p. 799Gupta Weiner, S.B.R., Morell, G., (2005) J. Appl. Phys., 97, p. 094307Morell, G., Gonzlez-Berríos, A., Weiner, B.R., Gupta, S., (2006) J. Mater. Sci: Mater. Electron, 17 (6), p. 443Koeck, F.A.M., Zumer, M., Nemanic, V., Nemanich, R.J., (2006) Diam. Rel. Mater., 15 (4-8), p. 880Shroder Nemanich, R.E.R.J., Glass, J.T., (1990) Phys. Rev., 41 (6), p. 3738Birrell, J., Gerbi, J.E., Auciello, O., Gibson, J.M., Johnson, J., Carlisle, J.A., (2005) Diam. Rel. Mater., 14 (1), p. 86Ferrari, A.C., Robertson, J., (2001) Phys. Rev., 63, pp. 121405RWu, K., Wang, E.G., Cao, Z.X., Wang, Z.L., Jiang, X., (2000) J. Appl. Phys., 88 (5), p. 2967Proffitt, S.S., Probert, S.J., Whitfield, M.D., Foord, J.S., Jackman, R.B., (1999) Diam. Rel. Mater., 8 (2-5), p. 76

IL-1 polymorphisms may predict unsuccessful dental implants?

AimThe aim of this study was to analyse the possible association between no success of dental implants and two polymorphisms, IL1A (-889) and IL1B (+3953), in a Caucasian Portuguese population, and a possible relationship with other potential risk variables associated with a peri-implant disease.Material and Methods155 unrelated Caucasian individuals, were divided into 2 groups: 100 with successful dental implant rehabilitations and 55 with unsuccessful ones. To identify the polymorphisms, in positions -889 of IL1A gene and +3953 of IL1B gene, was performed an oral mucosa scraping of the patients and the DNA obtained from epithelial cells. The data were analysed in the SPSS Statistics 17.0® and the statistic analysis included the independence test of the chi-square, the exact test of Fisher and techniques of analysis of binary logistic regression.ResultsThe estimated prevalence of polymorphisms of IL1A and IL1B gene, determined by the TGP (CGC Genetics, Portugal) results, in the Caucasian Portuguese population was of 33.5%.Success of rehabilitation with dental implants was more associated to a negative TGP result, whereas failure was found to be related to a positive result.Tobacco and alcohol consumption showed no statistically significant association with success or no success of the dental implants.ConclusionThe success of the dental implants was more associated with the presence of the allele 2 of the IL1A gene and the allele 2 of the IL1B gene.Tobacco and alcohol consumption showed no association with success or no success of the rehabilitation with dental implants

Characterization Of Boron Doped Nanocrystalline Diamonds

Nanostructured diamond doped with boron was prepared using a hot-filament assisted chemical vapour deposition system fed with an ethyl alcohol, hydrogen and argon mixture. The reduction of the diamond grains to the nanoscale was produced by secondary nucleation and defects induced by argon and boron atoms via surface reactions during chemical vapour deposition. Raman measurements show that the samples are nanodiamonds embedded in a matrix of graphite and disordered carbon grains, while morphological investigations using field electron scanning microscopy show that the size of the grains ranges from 20 to 100 nm. The lowest threshold fields achieved were in the 1.6 to 2.4 V/μm range. © 2008 IOP Publishing Ltd.100PART 5Himpsel, F.J., Knapp, J.A., VanVechten, J.A., Eastman, P.E., (1979) Phys. Rev., 20 B, p. 624Bandis, B., Pate, B.B., (1996) Appl. Phys Lett., 69, p. 366Mammana, V.P., Santos, T.E.A., Mammana, A., Baranauskas, V., Ceragioli, H.J., Peterlevitz, A.C., (2002) Appl. Phys. Lett., 81, p. 3470Baranauskas, V., Fontana, M., Ceragioli, H.J., Peterlevitz, A.C., (2004) Nanotech., 15 (10), pp. S678Shroder, R.E., Nemanich, R.J., Glass, J.T., (1990) Phys. Rev., 41 B, p. 3738Ferrari, A.C., Robertson, J., (2001) Phys. Rev., 63 B. , 121405(R)Jiang, X., Frederick, C.K.Au., Lee, S.T., (2002) J. Appl. Phys., 92 (5), p. 2880Lee, Y.C., Lin, S.J., Lin, I.N., Cheng, H.F., (2005) J. Appl. Phys., 97, p. 05431

Synthesis And Characterization Of Boron-doped Carbon Nanotubes

Boron-doped carbon nanotubes have been prepared by chemical vapour deposition of ethyl alcohol doped with B2O3 using a hot-filament system. Multi-wall carbon nanotubes of diameters in the range of 30 - 100 nm have been observed by field emission scanning electron microscopy (FESEM). Raman measurements indicated that the degree of C-C sp2 order decreased with boron doping. Lowest threshold fields achieved were 1.0 V/μm and 2.1 V/μm for undoped and boron-doped samples, respectively. © 2008 IOP Publishing Ltd.100PART 5Bonard, J.M., Kind, H., Stöckli, T., Nilsson, L.O., (2001) Sol. State Electron., 45, p. 893Maultzsch, J., Reich, S., Thomsen, C., Webster, S., Czerw, R., Carroll, D.L., Vieira, S.M.C., Rego, C.A., (2002) Appl.Phys.Lett., 81, p. 2647Mondal, K.C., Coville, N.J., Witcomb, M.J., Tejral, G., Havel, J., (2007) Chem. Phys. Lett., , in pressChen, C.F.C., Tsai, C.L., Lin, C.L., (2003) Diam. Rel. Mater., 12, p. 1500Sharma, R.B., Late Joag, D.S., Govindaraj Rao, C.N.R., (2006) Chem.Phys.Lett, 428, p. 102Mennella, V., Monaco, G., Colanoeli, L., Bussoletti, E., (1995) Carbon, 33 (2), p. 11

Neonatal Apex Resection Triggers Cardiomyocyte Proliferation, Neovascularization and Functional Recovery Despite Local Fibrosis

So far, opposing outcomes have been reported following neonatal apex resection in mice, questioning the validity of this injury model to investigate regenerative mechanisms. We performed a systematic evaluation, up to 180 days after surgery, of the pathophysiological events activated upon apex resection. In response to cardiac injury, we observed increased cardiomyocyte proliferation in remote and apex regions, neovascularization, and local fibrosis. In adulthood, resected hearts remain consistently shorter and display permanent fibrotic tissue deposition in the center of the resection plane, indicating limited apex regrowth. However, thickening of the left ventricle wall, explained by an upsurge in cardiomyocyte proliferation during the initial response to injury, compensated cardiomyocyte loss and supported normal systolic function. Thus, apex resection triggers both regenerative and reparative mechanisms, endorsing this injury model for studies aimed at promoting cardiomyocyte proliferation and/or downplaying fibrosis. In this article, Nascimento and colleagues demonstrate that neonatal apex resection stimulates cardiomyocyte proliferation and permanent scarring in the apex. Newly formed cardiomyocytes compensate muscle loss by resection, and resected hearts recover functional competence in adulthood. These findings endorse this model for studies aiming to block cardiac fibrosis and/or favoring CM proliferation

Efeito da Gliricidia sepium sobre nutrientes do solo, microclima e produtividade do milho em sistema agroflorestal no Agreste Paraibano.

Gliricidia sepium é uma leguminosa arbórea que tem sido utilizada em sistemas em aléias no semi-árido nordestino por apresentar bom desenvolvimento em condições de estresse hídrico. Entretanto, há pouca informação disponível sobre o efeito da introdução dessa espécie nos agroecossistemas da região. No presente estudo, objetivou-se avaliar a influência da distância de plantas de Gliricidia sepium sobre características da cultura do milho e do solo e microclima no Agreste Paraibano. O estudo foi realizado no município de Esperança (PB), em área de 0,5 ha, onde, em 1996, foram plantadas fileiras de G. sepium espaçadas 6 m entre si e com 1 m entre as árvores. Nesta área, em 2002, foram delimitadas quatro parcelas de 6 x 8 m e, em cada parcela, foi estabelecido um transeto perpendicular às fileiras de árvores com três posições de amostragem: (1) nas fileiras de árvores (0 m); (2) a 1 m das fileiras de árvores, e (3) a 3 m de distância das fileiras de árvores. O delineamento experimental utilizado foi em blocos casualizados com quatro repetições. A massa seca de folhedo caído embaixo da fileira de árvores foi de 1.390 kg ha-1 e diminuiu, gradativamente, para 270 kg ha-1 a 3 m de distância das árvores. As concentrações de P, K e matéria orgânica leve (MOL) embaixo das árvores foram maiores do que a 1 e 3 m de distância das fileiras. As médias mensais das temperaturas mínimas do ar e do solo embaixo e a 3 m das árvores foram similares. Entretanto, as médias mensais das temperaturas máximas do solo e do ar foram de 6 e 2 °C mais altas a 3 m das árvores, respectivamente, ao longo do período de estudo. A umidade do solo foi significativamente menor embaixo das árvores do que a 1 e 3 m de distância. O milho produziu mais grãos e palha e acumulou mais nutrientes nas posições mais próximas das fileiras de G. sepium