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81.
Douglas Fernandes Barbin Renata Pinheiro Sobottka Wagner Ezequiel Risso Claudemir Zucareli Elisa Yoko Hirooka 《光谱学快报》2013,46(2):73-79
Near-infrared spectroscopy is a rapid process analytical technology for measuring a wide range of constituents of biological materials. The objective of the current study was to investigate maize grains grown under different levels of fertilization and plant densities using near-infrared spectroscopy. Maize grains from the same plant density had their protein content increased with doses of nitrogen. In addition, it was observed the decrease in protein content with the increase in plant densities. Except for ash content, models for the assessed parameters indicated that near-infrared spectra has the potential for fast assessment of maize grains. 相似文献
82.
D. Pinheiro A. A. Pinto S. Z. Xanthopoulos A. N. Yannacopoulos 《Journal of Difference Equations and Applications》2013,19(1):59-95
We propose a projected gradient dynamical system as a model for a bargaining scheme for an asset for which the two interested agents have personal valuations that do not initially coincide. The personal valuations are formed using subjective beliefs concerning the future states of the world, and the reservation prices are calculated using expected utility theory. The agents are not rigid concerning their subjective probabilities and are willing to update them under the pressure to reach finally an agreement concerning the asset. The proposed projected dynamical system, on the space of probability measures, provides a model for the evolution of the agents, beliefs during the bargaining period and is constructed so that an agreement is reached under the minimum possible deviation of both agents from their initial beliefs. The convergence results are shown using techniques from convex dynamics and Lyapunov function theory. 相似文献
83.
M. V. Rocha M. S. Sthel M. G. Silva L. B. Paiva F. W. Pinheiro A. Miklòs H. Vargas 《Applied physics. B, Lasers and optics》2012,106(3):701-706
In this work we present a laser photoacoustic arrangement for the detection of the important greenhouse gas methane. A quantum-cascade
laser and a differential photoacoustic cell were employed. A detection limit of 45 ppbv in nitrogen was achieved as well as
a great selectivity. The same methodology was also tested in the detection of methane issued from natural gas powered vehicles
(VNG) in Brazil, which demonstrates the excellent potential of this arrangement for greenhouse gas detection emitted from
real sources. 相似文献
84.
Tiago Pinheiro Braga Elis Cristina Chagas Gomes Adriano Freitas de Sousa Neftali Lenin Villarreal Carreño Elisane Longhinotti Antoninho Valentini 《Journal of Non》2009,355(14-15):860-866
Hybrid mesoporous spheres of Al and Si oxides were synthesized for the mixture of organic material (chitosan) with inorganic material (aluminum and silicon hydroxide). It was observed that chitosan with larger polymerization degree, resulted in a larger mechanical resistance of the spheres. The oxides were characterized by the following: Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), differential scanning calorimetry (DSC), as well as, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and adsorption isotherms of N2 (BET). Highly uniform oxide sphere diameters were obtained (average of 1.0 mm). The results of the adsorption isotherms indicated that the material is mesoporous. The surface area of the materials ranged between 620 and 245 m2/g, and the pore volume varied between 0.82 and 0.28 cm3/g, depending on the molar ratio of the organic and inorganic materials. 相似文献
85.
Tatiele C. do Nascimento Pricila N. Pinheiro Andrêssa S. Fernandes Patrícia A. Caetano Eduardo Jacob-Lopes Leila Q. Zepka 《Molecules (Basel, Switzerland)》2022,27(10)
This study aimed to investigate the bioaccessibility of carotenoids and chlorophylls from the biomass of microalgae Chaetoceros calcitrans. The samples were submitted to an in vitro digestion protocol, and the compounds were determined by HPLC-PDA-MS/MS. A total of 13 compounds were identified in all tests. After in vitro digestion, the relative bioaccessibility of carotenoids and chlorophylls ranged from 4 to 58%. The qualitative profile of carotenoids reflected the initial sample, with all-E-zeaxanthin (57.2%) being the most bioaccessible compound, followed by all-E-neochrome (31.26%), the latter being reported for the first time in the micellar fraction. On the other hand, among the chlorophylls only pheophytin a (15.01%) was bioaccessible. Furthermore, a chlorophyll derivative (Hydroxypheophytin a’) was formed after in vitro digestion. Considering all compounds, xanthophylls (12.03%) and chlorophylls (12.22%) were significantly (p < 0.05) more bioaccessible than carotenes (11.22%). Finally, the considerable individual bioaccessibilities found, especially for zeaxanthin, demonstrate the bioactive potential of this bioresource. However, the large reduction in the totality of compounds after in vitro digestion suggests that additional technological strategies should be explored in the future to increase the efficiency of micellarization and enhance its bioactive effects. 相似文献
86.
Gianluigi Del Magno João Lopes Dias Pedro Duarte José Pedro Gaivão Diogo Pinheiro 《Communications in Mathematical Physics》2014,329(2):687-723
We prove that polygonal billiards with contracting reflection laws exhibit hyperbolic attractors with countably many ergodic SRB measures. These measures are robust under small perturbations of the reflection law, and the tables for which they exist form a generic set in the space of all convex polygons. Specific polygonal tables are studied in detail. 相似文献
87.
Costa Renyer A. Oliveira Kelson M. T. de Cássia Saraiva Nunomura Rita Junior Earle Silva A. Pinheiro Maria Lucia B. Costa Emmanoel V. Barison Andersson 《Structural chemistry》2018,29(1):299-314
Structural Chemistry - A theoretical and experimental DFT study of the vibrational, structural, and quantum properties of 9-methoxy-canthin-6-one (I) and... 相似文献
88.
Adriana C. Pinheiro Adriana C. A. Casagrande Osvaldo L. Casagrande Jr. 《Journal of polymer science. Part A, Polymer chemistry》2014,52(24):3506-3512
A series of linear low‐density polyethylene (LLDPE) nanocomposites containing different types of nanofiller (TiO2, MWCNT, expanded graphite, and boehmite) were prepared by in situ polymerization using a tandem catalyst system composed of {TpMs}NiCl ( 1 ) and Cp2ZrCl2 ( 2 ), and analyzed by differential scanning calorimetry, dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM). Based on these analyses, the filler content varied from 1.30 to 1.80 wt %. The melting temperatures and degree of crystallinity of the LLDPE nanocomposites were comparable to those of neat LLDPE. The presence of MWCNT as well as boehmite nucleated the LLDPE crystallization, as indicated by the increased crystallization temperature. The DMA results showed that the presence of TiO2, EG, and CAM 9080 in the LLDPE matrix yielded nanocomposites with relatively inferior mechanical properties compared to neat LLDPE, suggesting heterogeneous distribution of these nanofillers into the polymer matrix and/or the formation of nanoparticle aggregates, which was confirmed by TEM. However, substantial improvement in the storage modulus was achieved by increasing the sonication time. The highest storage modulus was obtained using MWCNT (1.30 wt %). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3506–3512 相似文献
89.
J. D. Pinheiro Filho E. S. De Almeida E. Z. Bilbao R. C. Santos A. X. Da Silva V. Sciani P. R. Rela 《Radiation measurements》1994,23(4):743-748
In this paper, we study the thermal annealing of proton tracks of 4 and 6 MeV at temperatures ranging from 150 to 240°C in CR-39 polymer detectors. A special experimental set-up for irradiating the detectors was arranged to obtain adequate proton beams from the Cyclotron CV-28 at IPEN/SP, Brazil. We report experimental data on track densities, track diameters, and activation energies based on current annealing models for the annealing of proton tracks in the energy range investigated. A value of (0.20±0.02)eV was determined as the mean activation energy of the annealing process in CR-39 detectors. 相似文献
90.
Ferreira C.M. Alves L.L. Pinheiro M. Sa A.B. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(2):229-239
A kinetic study of low-pressure microwave discharges in Ar, He, and O2 is carried out using electron-transport parameters and rate coefficients derived from solutions to the Boltzmann equation, together with the continuity and transport equations for the charged particles, taking into account stepwise-ionization processes. The Boltzmann equation is solved over a wide range of the applied frequency, ω/2π, but assuming that the angular frequency ω>τ e-1, with τe, denoting the characteristic time for electron-energy relaxation by collisions. The formulation provides discharge characteristics for the maintenance field and for mean absorbed power per electron in the three gases, which are shown to agree satisfactorily with experimental data obtained from surface-wave discharges. It is shown that such an agreement would not always be obtained without consideration of the role played by stepwise-ionization processes in sustaining the discharge 相似文献