Carlos Kenichi Suzuki

Carbon materials obtained from self-binding sugar cane bagasse and deciduous wood residues plastics

Abstract It is demonstrated that dispersed biomass residues (bagasse, sawdust) can be processed into hard carbonaceous blocks, panels or boards with good strength and thermodynamic properties. There are two possible approaches: to mould dispersed biomass charcoal with a phenol–formaldehyde binder or to produce this material by carbonising the biomass fiberboard prepared by making use of steam explosion autohydrolysis pulp or steam explosion lignin as a binder. In the first step, steam explosion lignin, as a modifier and a binder is introduced to the lignocellulosic biomass by impregnation or during the hot pressing process to form a hard fiberboard. By subsequent carbonisation of the fiberboard panels or blocks, carbonised panels or blocks with high bending and crushing strength and suitable thermodynamic properties are obtained due to the formation of an internal lignin reinforcement in cell lumina and impregnation of cell walls with lignin solution or molten lignin. The carbonised panels demonstrate a good dimensional stability after a standard treatment with water. The bending strength of the carbonised panels after 24 h soaking in water is 93% of that in dry state. The thermodynamic properties and porosity of the carbonised panels demonstrate their suitability for use as a building material. Lignin, a natural binder of fiberboards, has proven to be suitable for preparation of cabonaceous panels and boards. In this respect new carbon building blocks and panels from moulded biomass and carbonised steam exploded biomass act as a concentrated form of long term carbon storage and will be a factor stabilizing the growing CO2 concentration in the atmosphere. [Proceedings of the First Workshop of QITS, Materials Life-Cycle and Environmentally Sustainable Development, March 2–4, Campinas, UNU/IAS San Paulo, Brazil, 1998, pp. 95–101; Proceedings of the Workshop in “Targeting Zero Emissions for the Utilization of Renewable Resources”, ANESC, Tokyo, 1999, pp. 2–11.]

Real-time optical fibre sensor for hydro-alcoholic solutions

The fast determination of ethanol–water concentration in alcohol distillation plants is a primordial requirement to preserve the quality and reduce production losses. The present research proposes an optical fibre sensor for the measurement of hydro-alcoholic concentration in liquids based on the Fresnel reflection principle. The reflection intensities of ethanol samples with 0–100% of water content were measured at different temperatures for 1310 nm and 1550 nm wavelengths. Calibration curves were prepared by fitting the experimental data and implemented in a computer algorithm. According to the functional tests, the sensor is capable of identifying samples with less than 1% error on concentration and providing practically real-time analysis.

Impurity content characterization of brazilian quartz lascas

Lattice impurities (Al, Li, Fe) free from the influence of cations in inclusion liquid were evaluated by atomic absorption spectrophotometry (AAS) in quartz lascas taken from 10 deposits with known localities in three states, Minas Gerais, Tocantins and Bahia. Levels of Al content and associated Li content depend on the localities of deposits. Quartz deposit regions with high Al content are composed of granite, gneiss, and pegmatite as surrounding rocks. It was concluded that the charge compensation for Al-Si substitution in quartz lascas was realized substantially by the formation of Al-Li and Al-OH centers which were confirmed from the linear relation of Al-Li plots by AAS data and IR spectra due to Al-OH center. The variety in Al-Li and Al-OH correlations was attributed to the fluctuation of growing conditions of quartz in nature.

Effect of Impurity Segregation on Crystal Morphology of Y-Bar Synthetic Quartz

The effects of Al and H impurities on the crystal morphology of Y-bar synthetic quartz were studied. The growth velocities perpendicular to the Y-axis were evaluated in relation to the Al and H impurity segregations on the growth interfaces. It was found that the -X-growth region has the highest H content and shows the lowest growth velocity, due to the effect of H2O adsorbed on the growth interface in hydrothermal solution. Therefore, the -X-face, (20), always becomes larger in size. Al has a selective effect on the (112) and (2) faces to suppress the growth velocities and thus is important for crystal morphology. The growth velocities perpendicular to these faces, however, are controllable by the Al impurity content in the nutrient.

High-resolution measurements of nuclear Bragg scattering from a synthetic α-57Fe2O3 crystal

Nuclear Bragg scattering from a synthesized α-57Fe2O3 crystal was observed with 450 cps at beamline 16 of the Photon Factory. Mossbauer absorption spectra of the scattered beam were measured by oscillating the scatterer crystal while maintaining its Bragg condition. Time distribution of the scattered beam was measured with 300 ps resolution.

SiO2–GeO2 Soot Preform as a Core for Eu2O3 Nanocoating: Synthesis and Photophysical Study

Nowadays solid state chemists have the possibility of work with low temperature strategies to obtain solid state materials with appropriate physical and chemical properties for useful technological applications. Photonic core shell materials having a core and shell domains composed by a variety of compounds have been synthesized by different methods. In this work we used silica-germania soot prepared by vapor-phase axial deposition as a core where a nanoshell of Eu2O3 was deposited. A new sol-gel like method was used to obtain the Eu2O3 nanoshell coating the SiO2–GeO2 particles, which was prepared by the polymeric precursor method. The photophysical properties of Eu3+ were used to obtain information about the rare earth surrounding in the SiO2–GeO2@Eu2O3 material during the sintering process. The sintering process was followed by the luminescence spectra of Eu3+ and all the samples present the characteristic emission related to the 5D0→7FJ (J = 0, 1, 2, 3 and 4). The ratios of the 5D0→7F2/5D0→7F1 emission intensity for the SiO2–GeO2@Eu2O3 systems were calculated and it was observed an increase in its values, indicating a low symmetry around the Eu3+ as the temperature increases.

Crystalline and amorphous phases of GeO2 in VAD silica–germania soot preform

In germanium doped optical fiber, produced by vapor-phase axial deposition (VAD) technique, the refractive index profile is controlled by the radial distribution profile of germanium. At the porous soot state, GeO2 may be deposited as amorphous and/or crystalline phases in a SiO2‐GeO2 system. To correlate the quantitative deposition between amorphous and crystalline phases of GeO2, several silica‐germania soot preforms were prepared under diAerent deposition conditions and their X-ray diAraction (XRD) patterns and X-ray fluorescence spectra were analyzed. The presence of GeO2 crystalline (hexagonal) phase was detected in all soot samples, and its concentration was aAected by deposition conditions, mainly the soot surface temperature and H2/O2 ratio in the flame. The concentration of the crystalline phase is minimum at the center of the silica‐germania soot preform and increases along the radial direction. The greater concentrations at the outer diameter of the silica‐germania soot preform are due to the lower deposition temperature ( 850∞C). The GeO2 is eliminated at the center of preform in reductive atmosphereOH2=O2 > 2U and higher temperature (T 1000∞C), independently of SiCl4/GeCl4 ratio. These results are important to understand the main parameters of the doping process, to produce high quality materials with a given germanium concentration profile. ” 2000 Elsevier Science B.V. All rights reserved.

Flexible Optical Fiber Bending Transducer for Application in Glove-Based Sensors

The development of a low-cost and flexible optical fiber transducer for measurement of angular displacements is reported. The light intensity attenuation due to fiber microbending losses is correlated to the variations in flexing angle, yielding to a sensitivity of 1.80°. The device was also mounted in a fabric glove to the monitoring of flexion and abduction movements of index and thumb fingers. Once calibrated by a simple procedure, the glove-based system was capable to measure the angular positions with average errors <;5° and 7° for interphalangeal and metacarpophalangeal joints, respectively. Additionally, the repeatability analysis resulted in average range and standard deviations of 8.06° and 3.45°, respectively. The optical fiber sensor provides a low-cost alternative to the real-time monitoring of hand posture, and can be suitable for applications in human-robot and human-computer interactions.

X-ray topographic characterization of epitaxially grown diamond film

Abstract X-ray double crystal diffraction topography of homoepitaxial diamond film grown by microwave plasma chemical vapor deposition has been conducted to-study the residual stress generated by the lattice mismatch and defects at the film-substrate interface. Even though the stress-relaxation mechanism occurs by uniform film cracking, and there is no bending effect, a relatively large strain ( Δd d = 8.7 × 10 −4 ) still remains. Based on the X-ray topographic observation, a strain distribution model with alternate unstrained and tensioned regions is suggested.

Optical fiber specklegram sensor analysis by speckle pattern division

An optical fiber specklegram sensor interrogation method based on speckle pattern fragmentation is presented. The acquired specklegram images are divided in a square grid, creating sub-images that are further processed by a correlation technique, allowing the quantification of localized changes in the specklegrams. The methodology was tested on the assessment of linear displacements using a microbending transducer, by evaluating different grid sizes. For a 5×5 grid, a 2.53  mm-1 sensitivity over a 0.27 mm range was obtained, representing an extension of 237.5% in comparison to the standard interrogation technique. Therefore, the presented technique allows enhancing the sensor dynamic range without modifying the experimental setup.