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91.
Samples of a typical tetrameric protein, the hemoglobin, at the concentration of 150 mg/ml in bidistilled water solution, were exposed to a uniform magnetic field at 200 mT at different temperatures of , and . Fourier Transform Infrared Spectroscopy was used to analyze the response of the secondary structure of the protein to both stress agents, heating and static magnetic field. The most relevant result which was observed was the significant increasing in intensity of the Amide I band after exposure to the uniform magnetic field at the room temperature of . This result can be explained assuming that protein's α-helices aligned along the direction of the applied magnetic field due to their large dipole moment, inducing the alignment of the entire protein. Increasing of temperature up to and induced a significant reduction of the increasing in intensity of the Amide I band. This effect may be easily explained assuming that Brownian motion of the protein in water solution caused by thermal molecular agitation increased with increasing of temperature, contrasting the effect of the torque of the magnetic field applied to the protein in water solution. 相似文献
92.
93.
The effects of cooking by microwave oven on the secondary structure of lipid and protein contents in bovine ground beef were investigated in the midinfrared region by Fourier transform infrared (FTIR) spectroscopy to highlight the nonthermal effects of microwave oven heating. Samples of bovine ground beef were cooked in a conventional electric oven at the temperature of 175°C for 15 min and in a microwave oven at 800 W for 1½ min. Spectra analyses of bovine meat after cooking in the conventional oven evidenced a relevant increase in intensity of the carbonyl band at 1742 cm?1 and of the methylene group at 2921 and 2853 cm?1 that can be attributed to the Maillard reaction. In contrast, the increase in intensity of these bands after microwave oven heating was less than that which occurred after conventional cooking, showing that the temperature in ground beef meat samples during microwave heating was less than that induced by conventional heating. Spectral analysis in the amide I, II, and III regions showed that a significant increase in intensity occurred in the region from 1660 to 1675 cm?1 and around 1695, 1635, 1575, and 988 cm?1 after cooking by means of a microwave oven. These features, which can be attributed to β-turns and β-sheet structures, are characteristic of disorder processes in meat protein contents and increasing transition dipole coupling due to higher contents in aggregated β-sheet structures. This result highlighted nonthermal effects of microwave oven heating in the protein's secondary structure. 相似文献
94.
We explore a combinatorial theory of linear dependency in complex space, complex matroids, with foundations analogous to those for oriented matroids. We give multiple equivalent axiomatizations of complex matroids, showing that this theory captures properties of linear dependency, orthogonality, and determinants over ? in much the same way that oriented matroids capture the same properties over ?. In addition, our complex matroids come with a canonical S 1 action analogous to the action of ?? on a complex vector space. Our phirotopes (analogs of determinants) are the same as those studied previously by Below, Krummeck, and Richter-Gebert (Discrete and Computational Geometry, Springer, pp.?203?C233, 2003) and Delucchi (Diploma Thesis, ETH Zurich, 2003). We further show that complex matroids cannot have vector axioms analogous to those for oriented matroids. 相似文献
95.
The metriplectic framework, which allows for the formulation of an algebraic structure for dissipative systems, is applied to visco-resistive Magneto-Hydrodynamics (MHD), adapting what had already been done for non-ideal Hydrodynamics (HD). The result is obtained by extending the HD symmetric bracket and free energy to include magnetic field dynamics and resistive dissipation. The correct equations of motion are obtained once one of the Casimirs of the Poisson bracket for ideal MHD is identified with the total thermodynamic entropy of the plasma. The metriplectic framework of MHD is shown to be invariant under the Galileo Group. The metriplectic structure also permits us to obtain the asymptotic equilibria toward which the dynamics of the system evolves. This scheme is finally adapted to the two-dimensional incompressible resistive MHD, that is of major use in many applications. 相似文献
96.
We prove that the Fano variety of lines of a generic cubic fourfold containing a plane is isomorphic to a moduli space of twisted stable complexes on a K3 surface. On the other hand, we show that the Fano varieties are always birational to moduli spaces of twisted stable coherent sheaves on a K3 surface. The moduli spaces of complexes and of sheaves are related by wall-crossing in the derived category of twisted sheaves on the corresponding K3 surface. 相似文献
97.
Emanuele Massaro Franco Bagnoli Andrea Guazzini Pietro Lió 《Communications in Nonlinear Science & Numerical Simulation》2012,17(11):4294-4303
The problem of community detection is relevant in many scientific disciplines, from social science to statistical physics. Given the impact of community detection in many areas, such as psychology and social sciences, we have addressed the issue of modifying existing well performing algorithms by incorporating elements of the domain application fields, i.e. domain-inspired. We have focused on a psychology and social network-inspired approach which may be useful for further strengthening the link between social network studies and mathematics of community detection. Here we introduce a community-detection algorithm derived from the van Dongen’s Markov Cluster algorithm (MCL) method [4] by considering networks’ nodes as agents capable to take decisions. In this framework we have introduced a memory factor to mimic a typical human behavior such as the oblivion effect. The method is based on information diffusion and it includes a non-linear processing phase. We test our method on two classical community benchmark and on computer generated networks with known community structure. Our approach has three important features: the capacity of detecting overlapping communities, the capability of identifying communities from an individual point of view and the fine tuning the community detectability with respect to prior knowledge of the data. Finally we discuss how to use a Shannon entropy measure for parameter estimation in complex networks. 相似文献
98.
Bart Vermang Emanuele Cornagliotti Victor Prajapati Joachim John Jef Poortmans Robert Mertens 《固体物理学:研究快报》2012,6(6):259-261
This Letter discusses an important difference between positively charged SiO2 and negatively charged Al2O3 rear‐passivated p‐type Si solar cells: their illumination level dependency. For positively charged SiO2 rear‐passivated p‐type Si solar cells, a loss in short circuit current (JSC) and open circuit voltage (VOC) as a function of illumination level is mainly caused by parasitic shunting and a decrease in surface recombination, respectively. Hence, the relative loss in cell conversion efficiency, JSC, and VOC as a function of the illumination level for SiO2 compared to Al2O3 rear‐passivated p‐type Si solar cells has been measured and discussed. Subsequently, an exponential decay fit of the loss in cell efficiency is applied in order to estimate the difference in the energy output for both cell types in three different territories: Belgium (EU), Seattle and Austin (US). The observed trends in the difference in energy output between both cells, as a function of time of the year and region, are as expected and discussed. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
99.
100.
F. Frontera D. Dal Fiume T. Franceschini G. Landini E. Morelli M. Pamini A. Rubini S. Silvestri G. Spada E. Costa D. Cardini A. Emanuele 《Il Nuovo Cimento C》1984,7(6):656-672
Summary We describe a balloon experiment, currently in the marking, devoted to the observation of celestial X-ray sources. The main
features of the X-ray telescope are summarized as follows. It operates in the energy band from 20 to 300 keV. Its energy resolution
is about 17% at 60 keV. Under the hypothesis of 104 s of observing time, 3 mbar of residual atmospheric pressure and 3σ of statistical significance, the expected sensitivity
of the instrument is 2·10−6 photons/cm2 s keV in the (20÷200) keV energy band, corresponding to about 1 milliCrab. Its high sensitivity allows us to detect both
time variability in the flux and cyclotron lines in the spectra of X-ray sources. It has a field of view of 3° FWHM and has
the possibility of resolving complex fields by using multipitch modulation collimators. With such a configuration its angular
resolution is about 10′.
Paper presented at the 2° Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984. 相似文献