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Nm Wavelength Range (nm + wavelength_range)
Selected AbstractsGranulation sensing of first-break ground wheat using a near-infrared reflectance spectrometer: studies with soft red winter wheats,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2003Melchor C Pasikatan Abstract A near-infrared reflectance spectrometer, previously evaluated as a granulation sensor for first-break ground wheat from six wheat classes and hard red winter (HRW) wheats, was further evaluated for soft red winter (SRW) wheats. Two sets of 35 wheat samples, representing seven cultivars of SRW wheat ground by an experimental roller mill at five roll gap settings (0.38, 0.51, 0.63, 0.75 and 0.88,mm), were used for calibration and validation. Partial least squares regression was applied to develop the granulation models using combinations of four data pretreatments (log(1/R), baseline correction, unit area normalisation and derivatives) and subregions of the 400,1700,nm wavelength range. Cumulative mass of size fraction was used as reference value. Models that corrected for path length effects (those that used unit area normalisation) predicted the bigger size fractions well. The model based on unit area normalisation/first derivative predicted 34 out of 35 validation spectra with standard errors of prediction of 3.53, 1.83, 1.43 and 1.30 for the >1041, >375, >240 and >136,µm size fractions respectively. Because of less variation in mass of each size fraction, SRW wheat granulation models performed better than the previously reported models for six wheat classes. However, because of SRW wheat flour's tendency to stick to the underside of sieves, the finest size fraction of these models did not perform as well as the HRW wheat models. © 2003 Society of Chemical Industry [source] Fluorescence Lifetime Spectroscopy of Glioblastoma Multiforme,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2004Laura Marcu ABSTRACT Fluorescence spectroscopy of the endogenous emission of brain tumors has been researched as a potentially important method for the intraoperative localization of brain tumor margins. We investigated the use of time-resolved, laser-induced fluorescence spectroscopy for demarcation of primary brain tumors by studying the time-resolved spectra of gliomas. The fluorescence of human brain samples (glioblastoma multiforme, cortex and white matter: six patients, 23 sites) was induced ex vivo with a pulsed nitrogen laser (337 nm, 3 ns). The time-resolved spectra were detected in a 360,550 nm wavelength range using a fast digitizer and gated detection. Parameters derived from both the spectral- (intensities from narrow spectral bands) and the time domain (average lifetime) measured at 390 and 460 nm were used for tissue characterization. We determined that high-grade gliomas are characterized by fluorescence lifetimes that varied with the emission wavelength (>3 ns at 390 nm, <1 ns at 460 nm) and their emission is overall longer than that of normal brain tissue. Our study demonstrates that the use of fluorescence lifetime not only improves the specificity of fluorescence measurements but also allows a more robust evaluation of data collected from brain tissue. Combined information from both the spectraland the time domain can enhance the ability of fluorescencebased techniques to diagnose and detect brain tumor margins intraoperatively. [source] High efficiency AlGaInN-based light emitting diode in the 360,380 nm wavelength rangePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003Hisao Sato Abstract High performance LEDs emitting in the wavelength range 360,380 nm, are fabricated on sapphire substrates by one-time metalorganic chemical vapor deposition (MOCVD) without using epitaxial lateral overgrowth (ELO) or similar techniques. By improving layer structures and growth conditions, the output power of the LEDs was much improved. The light output power of the LEDs at an injection current of 20 mA is 3.2 mW, 2.5 mW and 1 mW at wavelengths of 378 nm, 373 nm and 363 nm, which correspond to an external quantum efficiency of 4.8%, 3.8% and 1.4%, respectively. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Low threshold GaInAs quantum well lasers grown under low growth rate by solid-source MBE for 1200 nm wavelength rangePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2006M. Ohta Abstract Optical property dependence on growth rates of highly-strained GaInAs quantum wells (QWs) on GaAs was studied by solid-source molecular beam epitaxy (MBE). Noticeable improvement of the photoluminescence (PL) was observed by lowering the growth rate of highly-strained GaInAs. A sample grown at a growth rate of 0.05 µm/h under a low growth temperature and high As pressure showed a high PL intensity and a flat surface in atomic force microscope (AFM) measurements. The lowest threshold current density of 117 A/cm2/well is achieved for GaInAs/GaAs double QW lasers at 1190 nm wavelength. A low growth rate is found to be effective to grow highly-strained GaInAs QWs. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Experimental testing of a random medium optical model of porous silicon for photovoltaic applicationsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2001A. A. Abouelsaood We have developed a model for light propagation in porous silicon (PS) based on the theory of wave propagation in random media. The low porosity case is considered, with silicon being the host material assuming randomly distributed spherical voids as scattering particles. The specular and the diffuse part of the light could be determined and treated separately. The model is applied to the case in which porous silicon would be used as a diffuse back reflector in a thin-film crystalline silicon solar cell realized in an ultrathin (1,3,,m) epitaxially grown Si layer on PS. Three,layer structures (epi/PS/Si) have been fabricated by atmospheric pressure chemical vapor deposition (APCVD) of 150,1000 nm epitaxial silicon layers on silicon wafers of which 150,450 nm of the surface has been electrochemically etched. An excellent agreement is found between the experimentally measured reflection data in the 400,1000 nm wavelength range and those calculated using the proposed model. The values of the layer thickness agree, within a reasonable experimental error, with those obtained independently by cross,sectional transmission electron microscopy (XTEM) analysis. This provides an experimental verification of the random,medium approach to porous silicon in the low porosity case. The analysis shows that the epitaxial growth process has led to appreciable porosity decrease of an initially high,porosity layer from about 60% to 20,30%. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||