Hard Hydrogenated Carbon Films With Low Stress

Analysis of hard a-C:H films with low stress prepared by methane plasma decomposition is reported. Films with hardness as high as 14 GPa and stress as low as 0.5 GPa were obtained. These films have a high Raman Id/Ig ratio (∼1.0), and small Tauc's band gap (∼0.4 eV). This letter also supplies strong evidence that the subimplantation deposition model, used to explain the formation of ta-C and ta-C:H films, is also valid for a-C:H films deposited by methane plasma decomposition. It is proposed that the rigidity of the films is basically provided by a matrix of dispersed cross-linked sp2 sites, in addition to the contribution of the sp3 sites. © 1998 American Institute of Physics.735617619Franceschini, D.F., Achete, C.A., Freire Jr., F.L., (1992) Appl. Phys. Lett., 60, p. 3229Chhowalla, M., Yin, Y., Amaratunga, G.A.J., McKenzie, D.R., Frauenheim, T., (1996) Appl. Phys. Lett., 69, p. 2344Hoffman, R.W., (1996) Physics of Thin Films, 3. , in edited by G. Hass and R. E. Thun Academic, New YorkJiang, X., Reichelt, K., Stritzker, B., (1989) J. Appl. Phys., 66, p. 5805Lifshitz, Y., Kasi, S.R., Rabalais, J.W., (1989) Phys. Rev. Lett., 68, p. 620Lifshitz, Y., Kasi, S.R., Rabalais, J.W., (1990) Phys. Rev. B, 41, p. 10468McKenzie, D.R., Muller, D., Pailthorpe, B.A., (1991) Phys. Rev. Lett., 67, p. 773Fallon, P.J., Veerasamy, V.S., Davis, C.A., Robertson, J., Amaratunga, G.A.J., Milne, W.I., Koskinen, J., (1993) Phys. Rev. B, 48, p. 4777Weiler, M., Sattel, S., Jung, K., Ehrhardt, H., Veerasamy, V.S., Robertson, J., (1994) Appl. Phys. Lett., 64, p. 2797Robertson, J., (1993) Diamond Relat. Mater., 2, p. 984Davis, C.A., (1993) Thin Solid Films, 226, p. 30Kohler, K., Coburn, J.W., Horne, D.E., Kay, E., (1985) J. Appl. Phys., 57, p. 59Chapman, B., (1980) Glow Discharge Process, , Wiley, New YorkMoller, W., (1993) Appl. Phys. A: Solids Surf., 56, p. 527Kleber, R., Weiler, M., Kruger, A., Sattel, S., Kunz, G., Jung, K., Ehrbardt, H., (1993) Diamond Relat. Mater., 2, p. 246Robertson, J., (1992) Phys. Rev. Lett., 68, p. 220Tamor, M.A., Vassell, W.C., Carduner, K.R., (1991) Appl. Phys. Lett., 58, p. 592Walters, J.K., Honeybone, P.J.R., Huxley, D.W., Newport, R., Howells, W.S., (1994) Phys. Rev. B, 50, p. 831Stephan, U., Frauenheim, T., Blaudeck, P., Jungnickel, G., (1994) Phys. Rev. B, 49, p. 1489Robertson, J., (1996) J. Non-Cryst. Solids, 198-200, p. 614Robertson, J., (1997) Diamond Relat. Mater., 6, p. 212Schwan, J., Ulrich, S., Batori, V., Ehrhardt, H., Silva, S.R.P., (1996) J. Appl. Phys., 80, p. 440Tamor, M., Vassel, W., (1994) J. Appl. Phys., 76, p. 446Prawer, S., Nugent, K.W., Lifshitz, Y., Lampert, G.D., Grossman, E., Kulik, J., Kalish, R., (1996) Diamond Relat. Mater., 5, p. 433Robertson, J., (1994) Pure Appl. Chem., 66, p. 1789Robertson, J., (1992) Surf. Coat. Technol., 50, p. 185Kelires, P.C., (1994) Phys. Rev. Lett., 73, p. 2460Amaratunga, G.A.J., Chhowalla, M., Kiely, C.J., Alexandrou, I., Devenish, R.M., (1996) Nature (London), 383, p. 32

Effects Of Stress On Electron Emission From Nanostructured Carbon Materials

The electron field emission from a graphite like amorphous carbon film was investigated. Threshold fields as low as 8 V/νm were observed at an assisting energy of 400eV. The field emission characteristics of the films were explained in terms of the high sp2 concentration, and the high intrinsic compressive stress modifying the electronic band structure of the film/graphitic nanostructures.21417101714McKenzie, D.R., Muller, D., Pailthope, B.A., (1991) Phys. Rev. Lett., 67, p. 773Schwan, J., Ulrich, S., Theel, T., Roth, H., Ehrhardt, H., Becker, P., Silva, S.R.P., (1997) J. Appl. Phys., 82, p. 6024Lifshitz, Y., Kasi, S.R., Rabalais, J.W., Eckstein, W., (1990) Phys. Rev. B, 41, p. 10468Robertson, J., (1993) Diamond Relat. Mater., 2, p. 984Lacerda, R.G., Hammer, P., Lepienski, C.M., Alvarez, F., Marques, F.C., (2001) J. Vac. Sci. Technol. A, 19, p. 971Bhattacharyya, S., Subramanyam, S.V., (1997) Appl. Phys. Lett., 71, p. 632Kilic, C., Mehrez, H., Ciraci, S., (1998) Phys. Rev. B, 58, p. 7872Uher, C., Hockey, R.L., Ben-Jacob, E., (1987) Phys. Rev. B, 35, p. 4483Satyanarayana, B.S., Hart, A., Milne, W.I., Robertson, J., (1997) Appl. Phys. Lett., 71, p. 1430Carey, J.D., Forrest, R.D., Silva, S.R.P., (2001) Appl. Phys. Lett., 78, p. 2339Illie, A., Ferrari, C., Yagi, T., Robertson, J., (2000) Appl. Phys. Lett., 76, p. 2627De Lima M.M., Jr., Lacerda, R.G., Vilcarromero, J., Marques, F.C., (1999) J. Appl. Phys., 86, p. 4936Hoffman, R.W., (1966) Physics of Thin Films, 3, pp. 211-273. , edited by G. Hass and R. E. Thun (Academic, New YorkCarey, J.D., Silva, S.R.P., (2001) Appl. Phys. Lett., 78, p. 347Hammer, P., Victoria, N.M., Alvarez, F., (2000) J. Vac. Sci. Technol. A, 18, p. 2277Lifshitz, Y., Lempert, G.D., Grossman, E., Avigal, L., Uzan-Saguy, C., Kalish, R., Khlik, J., Rabalais, J.W., (1995) Diamond Relat. Mater., 4, p. 318Fallon, P.J., Veerasamy, V.S., Davis, C.A., Robertson, J., Amaratunga, G.A.J., Milne, W.I., Koskinen, J., (1993) Phys. Rev. B, 48, p. 4777Ahuja, R., Auluck, S., Trygg, J., Wills, J.M., Eriksson, O., Johansson, B., (1995) Phys. Rev. B, 51, p. 4813Reynolds, W.N., Goggin, P.R., (1960) Philos. Mag., 5, p. 1049Lynch, R.W., Drickamer, H.G., (1966) J. Chem. Phys., 44, p. 181Chaumet, P.C., Dufour, J.P., (1998) J. Electrost., 43, p. 145Hryd, R., Charlier, A., McRae, E., (1997) Phys. Rev. B, 55, p. 682

Strain and slackness of achilles tendon during passive joint mobilization via imaging ultrasonography

Background: In vivo study of the mechanical behavior of tendons may bring advances in evaluating the impact of intervention programs for flexibility and strength, in clinical practice and sports. Objective: The aim of this study was to quantify the relative strain and slackness of achilles tendons during passive mobilization, for four ankle joint angles and two knee angles. Methods: The displacement of the muscle-tendon junction was quantified by means of ultrasound images acquired during passive ankle mobilization, with the aid of an electrogoniometer and an electromyograph to ensure the achievement of the required angles and muscle inactivity, respectively. Results: The strain values ranged from 4.28%±2.37 to -0.94%±1.58 for the fully extended knee, and from 2.38%±1.63 to -2.32%±2.16% for the flexed knee. Conclusions: The values found in this study confirm those in the literature and demonstrate how the Achilles tendon participates in length changes in the muscle-tendon unit during passive movement. These results suggest that the mechanical properties of tendinous tissues affect the relationship between the length of muscle fibers and the joint angle, even during this type of movement

Amyotrophic lateral sclerosis: one or multiple causes?

The Amyotrophic lateral sclerosis (ALS) is the most common form of motor neuron disease in the adulthood, and it is characterized by rapid and progressive compromise of the upper and lower motor neurons. The majority of the cases of ALS are classified as sporadic and, until now, a specific cause for these cases still is unknown. To present the different hypotheses on the etiology of ALS. It was carried out a search in the databases: Bireme, Scielo and Pubmed, in the period of 1987 to 2011, using the following keywords: Amyotrophic lateral sclerosis, motor neuron disease, etiology, causes and epidemiology and its similar in Portuguese and Spanish. It did not have consensus as regards the etiology of ALS. Researches demonstrates evidences as regards intoxication by heavy metals, environmental and occupational causes, genetic mutations (superoxide dismutase 1), certain viral infections and the accomplishment of vigorous physical activity for the development of the disease. There is still no consensus regarding the involved factors in the etiology of ALS. In this way, new research about these etiologies are necessary, for a better approach of the patients, promoting preventive programs for the disease and improving the quality of life of the patients

The Kuiper Belt and Other Debris Disks

We discuss the current knowledge of the Solar system, focusing on bodies in the outer regions, on the information they provide concerning Solar system formation, and on the possible relationships that may exist between our system and the debris disks of other stars. Beyond the domains of the Terrestrial and giant planets, the comets in the Kuiper belt and the Oort cloud preserve some of our most pristine materials. The Kuiper belt, in particular, is a collisional dust source and a scientific bridge to the dusty "debris disks" observed around many nearby main-sequence stars. Study of the Solar system provides a level of detail that we cannot discern in the distant disks while observations of the disks may help to set the Solar system in proper context.Comment: 50 pages, 25 Figures. To appear in conference proceedings book "Astrophysics in the Next Decade

Dermatophylosis in Santa Inês sheep from Distrito Federal

Relataram-se quatro casos de dermatofilose em ovinos da raça Santa Inês, no período de um ano. Microscopicamente observaram-se filamentos na forma de "trilho de bonde" e zoósporos nos quatro casos. A tentativa do isolamento do microrganismo foi realizada por meio do método de Haalstra e em apenas um caso obteve-se sucesso, observando-se colônias de aparência lisa, formato circular, cor amarelada e hemolítica em ágar sangue. O exame direto com coloração de Gram mostrou-se um método bastante eficiente na confirmação da presença do microrganismo afetando a epiderme em razão da morfologia típica do agente.Four cases of dermatophylosis were reported in Santa Inês sheep in a study period of one year. Microscopically, septate filaments and coccoid forms zoospores were observed. Attempts to isolate the microorganisms were accomplished using Haastra's method and it was successful in only one case. Dermatophilus congolensis samples have grown on blood agar, colonies where hemolytic, small, round and pigmentation vary from yellow to orange. The gram staining method was efficient to confirm the presence of the microorganism affecting the epidermis due to typical morphology of the agent