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排序方式: 共有173条查询结果,搜索用时 15 毫秒
1.
Isaac Monroy Péter Bakonyi Germán Buitrón 《Clean Technologies and Environmental Policy》2018,20(7):1581-1588
Continuous hydrogen production stability and robustness by dark fermentation were comprehensively studied at laboratory scale. Continuous bioreactors were operated at two different hydraulic retention times (HRT) of 6 and 10 h. The reactors were subjected to feeding shocks given by decreases in the HRT, and therefore the organic loading increases, during 6 and 24 h. Results indicated that the H2 productivity was significantly improved by the temporary organic shock loads, increasing the hydrogen production rate up to 40%, compared to the rate obtained at the steady-state condition. Besides, it was observed that after the shock load, the stability of the reactor (measured as the hydrogen production rate) was recovered attaining the values observed before the feeding shocks. The bioreactor operated at shorter HRT (6 h) showed better H2 productivity (17.3?±?1.1 L H2/L-d) in comparison with the other one operated at 10-h HRT (12.4?±?1.6 L H2/L-d). 相似文献
2.
Cenobio-Galindo Antonio de Jesus Pimentel-González Diana Jaqueline Del Razo-Rodríguez Oscar Enrique Medina-Pérez Gabriela Carrillo-Inungaray María Luisa Reyes-Munguía Abigail Campos-Montiel Rafael Germán 《Food science and biotechnology》2019,28(5):1553-1561
Food Science and Biotechnology - The use of unconventional sources is very relevant in the food area. In the present study the development of active films with the addition of bioextract (BE) or... 相似文献
3.
Daiana Garcia Germán Barros Sofía Chulze Antonio J. Ramos Vicente Sanchis Sonia Marín 《Journal of the science of food and agriculture》2012,92(15):2952-2959
BACKGROUND: Fusarium graminearum and F. verticillioides are two very important mycotoxigenic species as they cause diverse diseases in crops. The effects of constant and cycling temperatures on growth and mycotoxin production of these species were studied on soybean based medium and on irradiated soya beans. RESULTS: F. graminearum grew better when was incubated at 15, 20 and 15–20 °C (isothermal or cycling temperature) during 21 days of incubation. Maximum levels of zearalenone and deoxynivalenol (39.25 and 1040.4 µg g?1, respectively) were detected on soya beans after 15 days of incubation and the optimal temperature for mycotoxin production was 15 °C for zearalenone and 20 °C for deoxynivalenol. F. verticillioides grew better at 25 °C in culture medium and at 15/20 °C and 15/25 °C on soybean seeds. Fumonisin B1 was produced only in culture medium, and the maximum level (7.38 µg g?1) was found at 15 °C after 7 days of incubation. CONCLUSION: When growth and mycotoxin production under cycling temperatures were predicted from the results under constant conditions, observed values were different from calculated for both species and substrate medium. Therefore, care should be taken if data at constant temperature conditions are to be extrapolated to real field conditions. Copyright © 2012 Society of Chemical Industry 相似文献
4.
Javier F. Urchueguía Víctor Espinosa Germán J. De Valcárcel 《Journal of Modern Optics》2013,60(10):1483-1493
Abstract The dynamics of a two-photon laser with injected signal (TPLIS) in the limit of high quality cavity (class-A laser) is analysed by explicitly considering the underlying multi-level structure of the amplifying medium. A three-level cascade system is considered which retains the basic physics of the microscopic lasing processes. In this way the usual two-photon laser equations are consistently modified by the appearance of different dynamic frequency shifts dependent on the two-photon population inversion and on the laser intensity (ac-Stark shift). Although the basic instability scenarios are not qualitatively modified with respect to the effective two-level TPLIS, from the quantitative point of view, population-induced shifts heavily affect the threshold of appearance of instabilities. 相似文献
5.
Research on seismic resistance and mechanic behavior of reinforced lightweight aggregate concrete walls after high temperature 下载免费PDF全文
This study focused on the mechanical behavior of reinforced lightweight aggregate concrete (RLAC) walls under repeated horizontal loads after a standard temperature‐rising fire‐resistance test and compared the specimen walls' ultimate loads, yielding loads, cracked loads, stiffness, and ductility with those of reinforced normal‐weight aggregate concrete (RNAC) walls. Steel reinforcing bar spacing, aggregate types, wall widths, and high temperatures were variables in this study. The experimental results showed that, after the fire‐resistance test, the smaller the steel reinforcing bar spacing of RLAC walls, the higher the yield and ultimate loads, yet the worse the ductility and the hysteresis loop's energy, whereas the greater the width of the wall, the greater the stiffness and the higher the hysteresis loop's energy. The differences in terms of stiffness, ductility, and hysteresis between RLAC walls with and without the fire‐resistance test were insignificant, indicating that RLAC walls do not lose their basic mechanical behavior during a high‐temperature fire. RNAC walls showed, indeed, a significant downward trend for strength and hysteresis after the fire‐resistance test, but the decrease was much less clear for stiffness. Therefore, RLAC walls did show better seismic resistance than RNAC walls under the same testing conditions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
6.
Ferran V. García-Ferrer Isabel Pérez-Arjona Germán J. de Valcárcel Eugenio Roldán 《Journal of Modern Optics》2013,60(5):763-773
It is well known that the squeezing spectrum of the field exiting a nonlinear cavity can be directly obtained from the fluctuation spectrum of normally ordered products of creation and annihilation operators of the cavity mode. In this article we show that the output field squeezing spectrum can be derived also by combining the fluctuation spectra of any pair of s -ordered products of creation and annihilation operators. The interesting result is that the spectrum obtained in this way from the linearized Langevin equations is exact, and this occurs in spite of the fact that no s -ordered quasiprobability distribution verifies a true Fokker–Planck equation; that is, the Langevin equations used for deriving the squeezing spectrum are not exact. The (linearized) intracavity squeezing obtained from any s -ordered distribution is also exact. These results are exemplified in the problem of dispersive optical bistability. 相似文献
7.
8.
Abstract A simplified explicit formula for the displacement bounds of the beam‐column subjected to time‐dependent boundary constraints is proposed. The formula is derived by means of removing time dependence from the boundary conditions. The proposed bounds provide a quick estimation of the displacements for problems with complex loading conditions. 相似文献
9.
Juan Miguel Campanario Jes��s Carretero Vera Marangon Antonio Molina Germ��n Ros 《Scientometrics》2011,87(1):75-84
We studied the effect on journal impact factors (JIF) of citations from documents labeled as articles and reviews (usually peer reviewed) versus citations coming from other documents. In addition, we studied the effect on JIF of the number of citing records. This number is usually different from the number of citations. We selected a set of 700 journals indexed in the SCI section of JCR that receive a low number of citations. The reason for this choice is that in these instances some citations may have a greater impact on the JIF than in more highly-cited journals. After excluding some journals for different reasons, our sample consisted of 674 journals. We obtained data on citations that contributed to the JIF for the years 1998?C2006. In general, we found that most journals obtained citations that contribute to the impact factor from documents labeled as articles and reviews. In addition, in most of journals the ratio between citations that contributed to the impact factor and citing records was greater than 80% in all years. Thus, in general, we did not find evidence that citations that contributed to the impact factor were dependent on non-peer reviewed documents or only a few citing records. 相似文献
10.
Germán Sierra Gallego Joël Barrault Catherine Batiot-Dupeyrat Fanor Mondragón 《Catalysis Today》2010,149(3-4):365-371
LaNiO3 type perovskite was prepared by the “self-combustion” method and was used as catalyst precursor for the methane decomposition reaction at 600 and 700 °C. CH4 conversion reaches 80% at 700 °C and 65% at 600 °C using pure CH4. The yield of CNT and H2 were 2.2 gCNT g?1 h?1 and 8.2 L g?1 h?1 at 700 °C respectively after 4 h of reaction. When the reaction is prolonged to 22 h the catalytic activity decreases but the catalyst is still active, the production of hydrogen reaches 63.5 L (STP) per gram of catalyst and the production of MWCNT was equal to 17 g per gram of catalyst.Multi-wall carbon nanotubes were characterized by X-ray diffraction (XRD), surface area (BET), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Raman spectroscopy. TEM micrographs showed that MWCNT longer than 20 μm were formed with inner diameters ranging from 5 to 16 nm and outer diameters up to about 40 nm.The results obtained here clearly show that the use of the perovskite LaNiO3 as catalytic precursor is very effective for the simultaneous production of carbon nanotubes and hydrogen. 相似文献