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61.
M. Luz Silva F. X. Malcata 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1999,77(3):134-143
The effects of fermentation time and distillation cuts on the composition of distillates in terms of ethanal, 1,1-diethoxyethane, methanol, 1-butanol, 2-butanol, 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, ethyl acetate, ethyl 2-hydroxypropanoate, 3-methylbutyl acetate, hexyl acetate, 2-phenylethyl acetate, hexanol, trans-2-hexenol, trans-3-hexenol, cis-3-hexenol, 2-phenylethanol, ethyl butyrate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl dodecanoate, 2-methylpropanoic acid, 3-methylbutanoic acid, hexanoic acid, octanoic acid, decanoic acid, and dodecanoic acid were assessed through data generated according to a factorial design using analysis of variance and principal component analysis. Four times of storage of pomace obtained following winemaking of two grape varieties of white Verde wine (Alvarinho and Loureiro) and three distillation cuts were considered; volatile compounds in the 24 samples generated were analyzed directly, and indirectly after extraction and concentration, by capillary gas chromatography. The results generated have suggested clear differences (P<0.05) between distillate cuts obtained throughout fermentation times for each grape variety. The major differences between the different distillate fractions analyzed were accounted for by the contents of diethyl butanoate, ethyl 2-hydroxypropanoate, and the sum of 3-methylbutanoic and 2-methylpropanoic acids for Loureiro, whereas the main differences were accounted for by the contents of diethyl butanoate and the sum of the carboxylic acids for Alvarinho. 相似文献
62.
da Costa Silva F. Barroso de Assis Fonseca S. Soares A.J.M. Giarola A.J. 《Antennas and Propagation, IEEE Transactions on》1991,39(9):1398-1404
The use of dyadic Green's functions and the moment method is explored for the solution of microstrip antenna problems on circular cylindrical substrates. The dyadic Green's functions of the electric type are obtained for a medium consisting of three cylindrical dielectric layers concentric with a perfectly conducting cylinder, and integral equations are developed for the evaluation of the electromagnetic fields. The effect of a dielectric overlay on the resonant frequency of a cylindrical-rectangular microstrip antenna is analyzed. The patch is directly fed by means of a microstripline printed along the cylinder axial direction. The results show that the effect of the dielectric overlay is substantial when its relative permittivity and thickness are increased, such that this effect has to be very carefully considered in the design of microstrip antennas 相似文献
63.
de Souza M. e Silva F. de Melo M.T. Novo L.R.G.S.L. 《Microwave Theory and Techniques》2009,57(9):2224-2231
The authors have studied a new way to design an instantaneous frequency measurement subsystem (IFMS). The method is based on bandstop filters. The device uses rectangular open-loop resonators instead of delay lines. The resonance frequency is adjusted by a resonator perimeter that must be approximately a half-wavelength long, and also by coupling distance between the resonators and the main transmission line. Simulated and experimental results are presented for a 5-bit IFMS. 相似文献
64.
A.J. Keating J. Antoszewski K.K.M.B.D. Silva K.J. Winchester T. Nguyen J.M. Dell C.A. Musca L. Faraone P. Mitra J.D. Beck M.R. Skokan J.E. Robinson 《Journal of Electronic Materials》2008,37(12):1811-1820
Microspectrometers based on the monolithic integration of a microelectromechanical system (MEMS) Fabry–Pérot filter and a
Hg
x
Cd1–x
Te-based infrared detector are discussed and measured results presented. The microspectrometers are designed to operate in
the 1.5 μm to 2.6 μm wavelength range. Design equations are presented which account for the mechanical and optical characteristics of the device.
Measurements indicate linewidths as narrow as 55 nm, switching times of 40 μs, and a tuning range of 380 nm, which is limited by snap-down. Optical characterization of the distributed Bragg mirrors
and the Fabry–Pérot filter are presented, and these are shown to be in good agreement with simple first-order analytical models.
Bowing of the movable Fabry–Pérot mirror due to stress gradients is identified as the dominant source of linewidth broadening. 相似文献
65.
Optimal Predictive Control of Three-Phase NPC Multilevel Converter for Power Quality Applications 总被引:1,自引:0,他引:1
66.
A fast and efficient hybrid fractal-wavelet image coder. 总被引:1,自引:0,他引:1
Yuzo Iano Fernando Silvestre da Silva Ana Lúcia Mendes Cruz 《IEEE transactions on image processing》2006,15(1):98-105
The excellent visual quality and compression rate of fractal image coding have limited applications due to exhaustive inherent encoding time. This paper presents a new fast and efficient image coder that applies the speed of the wavelet transform to the image quality of the fractal compression. Fast fractal encoding using Fisher's domain classification is applied to the lowpass subband of wavelet transformed image and a modified set partitioning in hierarchical trees (SPIHT) coding, on the remaining coefficients. Furthermore, image details and wavelet progressive transmission characteristics are maintained, no blocking effects from fractal techniques are introduced, and the encoding fidelity problem common in fractal-wavelet hybrid coders is solved. The proposed scheme promotes an average of 94% reduction in encoding-decoding time comparing to the pure accelerated Fractal coding results. The simulations also compare the results to the SPIHT wavelet coding. In both cases, the new scheme improves the subjective quality of pictures for high-medium-low bitrates. 相似文献
67.
Juliana dos Santos Rafaela S. de Oliveira Thayse V. de Oliveira Maiara C. Velho Martina V. Konrad Guilherme S. da Silva Monique Deon Ruy C. R. Beck 《Advanced functional materials》2021,31(16):2009691
3D printing and nanotechnology have been two important tools in the development of therapeutic approaches for personalized medicine. More recently, their alliance has been improved in an effort to build innovative, versatile, multifunctional, and/or smart medical and pharmaceutical products. Therefore, an extensive review about scientific studies that ally 3D printing and nanomaterials in the development of new approaches for pharmaceutical and medical applications for the treatment and prevention of diseases is presented here. The articles are classified into five categories according to their main application: Cell growth and tissue engineering, antimicrobial, drug delivery, stimulus-response, and theranostics. Semisolid extrusion, inorganic nanoparticles, and cell growth and tissue engineering are the most reported 3D printing technique, type of nanomaterial, and application, respectively. The increase in papers dedicated to these areas is also notable, especially in the 2019 and 2020, when semisolid extrusion became the most used technique, overcoming fused deposition modelling. In fact, this review highlights that the possibility of an alliance between 3D printing and nanotechnology for the production of multiscale materials is undoubtedly a great opportunity for knowledge and innovation in the pharmaceutical and medical area. 相似文献
68.
Vanessa H. Fragal Elizngela H. Fragal Tao Zhang Xiaoxi Huang Thelma Sley P. Cellet Guilherme M. Pereira Andrei Jitianu Adley F. Rubira Rafael Silva Tewodros Asefa 《Advanced functional materials》2019,29(8)
In this work, the synthesis of high‐performance, metal ion‐imprinted, mesoporous carbon electrocatalysts for hydrazine oxidation reaction (HzOR) using casein or a family of phosphoproteins derived from cow's milk as a precursor is shown. The synthesis is made possible by mixing trace amounts of non‐noble metal ions (Fe3+ or Co2+) with casein and then producing different metal ions‐functionalized casein intermediates, which upon carbonization, followed by acid treatment, lead to metal ion‐imprinted catalytically active sites on the materials. The materials effectively electrocatalyze HzOR with low overpotentials at neutral pH and exhibit among the highest electrocatalytic performances ever reported for carbon catalysts. Their catalytic activities are also better than the corresponding control material, synthesized by carbonization of pure casein and other materials previously reported for HzOR. This work demonstrates a novel synthetic route that transforms an inexpensive protein to highly active carbon‐based electrocatalysts by modifying its surfaces with trace amounts of non‐noble metals. The types of metal ions employed in the synthesis are found to dictate the electrocatalytic activities of the materials. Notably, Fe3+ is found to be more effective than Co2+ in helping the conversion of casein into more electrocatalytically active carbon materials for HzOR. 相似文献
69.
Position sensitive photo-detectors (PSDs) utilize the lateral photovoltaic effect to produce an electrical output that varies linearly with the position of a light spot incident on a semiconductor junction. Design, fabrication and characterization of newly developed silicon PSD, which employ the planar technology and double ion implantation with different doses, are described. Shallow and low-doped p-n junction is formed by boron implantation in n-type silicon substrate. The position characteristics of PSD are symmetric to the zero and linear in the 80% of the active area. For a higher resistivity top layer (lower implanted dose), the sensitivity grows up and the linearity gets improved. The influence of the substrate is not substantial for the position characteristics. The response of the sensor, measured by pulsed 15 ns laser, was determined to be about 100 ns. Described PSD has been used in the construction of simple light spot rotational follower. 相似文献
70.
A novel method for performing greedy decompositions using generalised bit-planes is proposed. It provides an elegant solution to the tradeoff between quantisation of coefficients and number of passes in the matching pursuits algorithm. In addition, when replacing the matching pursuits algorithm in video coding, it provides a significant performance improvement 相似文献