CVD Diamond growth in the silicon substrates of large area

Diamond films were grown through Chemical Vapor Deposition (CVD) in silicon substrates (100) of large area (80 cm(2),), in a hot filament chemical vapor deposition (HFCVD), with growth rates over 1,5 mu m/h. The growth of samples was made with different gaseous fluxes and different methane percentages (CH(4)) in hydrogen (H(2)). The samples were analyzed through optical microscopy, Scanning Electron Microscopy and Raman spectroscopy scattering. Such analyzes showed the presence of a high purity diamond in all samples.63227928

Development of chemical vapor deposition diamond burrs using hot filament

The fabrication of boring tools (burrs) for dentistry with the use of a hot-filament chemical vapor deposition (CVD) system, to form the diamond abrading structure, is reported here. The diamond was synthesized from a methane/freon gas mixture diluted in hydrogen. Comparative drilling tests with conventional diamond burrs and the CVD diamond burrs in borosilicate glasses demonstrated a lifetime more than 20 times larger for the CVD diamond burrs. Also, heat flow experiments in dentine showed that the CVD diamond burrs induce temperature gradients of the same order as the conventional ones. These characteristics of the CVD diamond burrs are highly desirable for odontological applications where the burrs' lifetime and the low temperature processing are essential to the quality and comfort of the treatment. (C) 1996 American Institute of Physics.6751993199

Cytocompatibility studies of vertically-aligned multi-walled carbon nanotubes: Raw material and functionalized by oxygen plasma

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)It was presented a strong difference on cell adhesion and proliferation of functionalized vertically-aligned multi-walled carbon nanotube (VACNT) scaffolds compared to raw-VACNT. Biocompatibility in vitro tests were performed on raw-VACNT after superficial modification by oxygen plasma, which changes its superhydrophobic character to superhydrophilic. Two cytocompatibility tests were applied: 1) total lactate dehydrogenase colorimetric assay for the study of proliferating cells; and 2) cellular adhesion by scanning electron microscopy. Results showed that superhydrophilic VACNT scaffolds stimulate cell growth with proliferation up to 70% higher than normal growth of cell culture. (c) 2010 Elsevier B.V. All rights reserved.324648652Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Pesquisa e DesenvolvimentoFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2008/11642-5, 07/00013-4

Increasing mouse embryonic fibroblast cells adhesion on superhydrophilic vertically aligned carbon nanotube films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)We have analyzed the adhesion of mouse embryonic fibroblasts (MEFs) genetically modified by green fluorescence protein (GFP) gene cultured on vertically-aligned carbon nanotubes (VACNTs) after 6 days. The VACNTs films grown on Ti were obtained by microwave plasma chemical vapor deposition process using Fe catalyst and submitted to an oxygen plasma treatment, for 2 min, at 400 V and 80 mTorr, to convert them to superhydrophilic. Cellular adhesion and morphology were analyzed by scanning electron, fluorescence microscopy, and thermodynamics analysis. Characterizations of superhydrophilic VACNTs films were evaluated by contact angle and X-Ray Photoelectron Spectroscopy. Differences of crowd adhered cells, as well as their spreading on superhydrophilic VACNTs scaffolds, were evaluated using focal adhesion analysis. This study was the first to demonstrate, in real rime, that the wettability of VACNTs scaffolds might have enhanced and differential adherence patterns to the MEF-GFP on VACNTs substrates. (C) 2011 Elsevier B.V. All rights reserved.31715051511Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [07/00013-4, 06/03525-3

Cytotoxicity analysis of vertically aligned multi-walled carbon nanotubes by colorimetric assays

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)A new methodology to evaluate the acute cytotoxicity of vertically aligned multi-walled carbon nanotube (VACNT) scaffolds was presented. A comparison between three different colorimetric assays was performed: (i) lactate dehydrogenase,(ii)2-(4,5-dimethyl-2-thiazolyl)-3,5-diphenyl-2H-tetrazolium bromide, and (iii) neutral red. The results confirmed that a simple removing of VACNT scaffolds from the cell culture before the colorimetric assays, is necessary to obtain a high level of cell viability. (C) 2009 Published by Elsevier B.V.15921-2221652166Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2008/11642-5

Fast Preparation of Hydroxyapatite/Superhydrophilic Vertically Aligned Multiwalled Carbon Nanotube Composites for Bioactive Application

A method for the electrodeposition of hydroxyapatite films on superhydrophilic vertically aligned multiwalled carbon nanotubes is presented. The formation of a thin homogeneous film with high crystallinity was observed without any thermal treatment and with bioactivity properties that accelerate the in vitro biomineralization process and osteoblast adhesion.2623183081831

In vitro and in vivo studies of a novel nanohydroxyapatite/superhydrophilic vertically aligned carbon nanotube nanocomposites

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)An association between in vitro and in vivo studies has been demonstrated for the first time, using a novel nanohydroxyapatite/superhydrophilic vertically aligned multiwalled carbon nanotube (nHAp/VAMWCNT-O-2) nanocomposites. Human osteoblast cell culture and bone defects were used to evaluate the in vitro extracellular matrix (ECM) calcification process and bone regeneration, respectively. The in vitro ECM calcification process of nHAp/VAMWCNT-O-2 nanocomposites were investigated using alkaline phosphatase assay. The in vivo biomineralization studies were carried out on bone defects of C57BL/6/JUnib mice. Scanning electron microscopy, micro-energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and X-ray difractometry analyses confirmed the presence of the nHAp crystals. nHAp/VAMWCNT-O-2 nanocomposites induced in vitro calcification of the ECM of human osteoblast cells in culture after only 24 h. Bone regeneration with lamellar bone formation after 9 weeks was found in the in vivo studies. Our findings make these new nanocomposites very attractive for application in bone tissue regeneration.24717231732Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FVEFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FAPESP [2011/17877-7, 2011/20345-7

Synchrotron radiation X-ray analysis of boron-doped diamond films grown by hot-filament assisted chemical vapor deposition

This paper presents a synchrotron X-ray radiation analysis of boron-doped diamond films grown by hot-filament assisted chemical vapor deposition (HFCVD). The diamond films were grown at different doping levels with the introduction of boron to the gas mixture by bubbling hydrogen in a B2O3 solution in methanol. The B/C ratio in methanol varied from 2000 to 20 000 ppm and the gas flow rates were controlled so that boron incorporation to the film varied in the range from 10(18) to 10(21) boron/ cm(3). All other process parameters were kept unchanged to allow comparison only of the influence of the doping level. The film. analyses were performed at the X-ray diffraction beamline of the Laboratorio Nacional de Luz Sincrotron - LNLS, Brazil. The Debye-Scherrer configuration was used in this study. A high intensity monochromatic beam at lambda = 1.46 A was used and an excellent signal to noise ratio was obtained for 2theta varying from 20degrees to 150degrees. The difractogram for the undoped diamond film show intense peaks from the (111), (220), (311), (400) and (331) crystallographic planes. For the boron-doped films a set of new diffraction lines appear and their intensities increase considerably with the doping level. The set of diffraction peaks of similar intensities are related to a hexagonal structure and were assigned with hi-h confidence to tungsten carbide. This reveals that the boron-doping process in HFCVD facilitates the incorporation of tungsten carbide from the filament in the diamond film. The FWHM analysis of the diamond diffraction peaks shows a dependence of film crystallinity with doping level with a definite maximum at approximately 2.3 X 10(19) boron/cm(3). (C) 2002 Elsevier Science B.V. All rights reserved.11215315

Reduced graphene oxide and vertically aligned carbon nanotubes superhydrophilic films for supercapacitors devices

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Reduced graphene oxide (RGO) and vertically aligned carbon nanotubes (VACNT) superhydrophilic films were prepared by chemical vapor deposition techniques for electrical energy storage investigations. These electrodes were characterized in terms of their material and electrochemical properties by scanning electron microscopy (SEM), surface wettability, Fourier transform infrared spectroscopy (FTIR), energy dispersive and Raman spectroscopies, cyclic voltammetry (CV) and galvanostatic charge-discharge. We observed several physical structural and electrochemical similarities between these carbon-based materials with particular attention to very good specific capacitance, ultra-high energy storage and fast power delivery. Our results showed that the main difference between specific capacitance values is attributed to pseudocapacitive contribution and high density of multiwall nanotubes tips. In this work we have tested a supercapacitor device using the VACNT electrodes. (C) 2013 Elsevier Ltd. All rights reserved.49487493Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq