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排序方式: 共有768条查询结果,搜索用时 15 毫秒
31.
Birzabith Mendoza-Novelo Diego I. Alvarado-Castro José L. Mata-Mata Juan V. Cauich-Rodríguez Arturo Vega-González Eduardo Jorge-Herrero Francisco J. Rojo Gustavo V. Guinea 《Materials science & engineering. C, Materials for biological applications》2013,33(4):2392-2398
The present study investigates the potential use of non-catalyzed water-soluble blocked polyurethane prepolymer (PUP) as a bifunctional cross-linker for collagenous scaffolds. The effect of concentration (5, 10, 15 and 20%), time (4, 6, 12 and 24 h), medium volume (50, 100, 200 and 300%) and pH (7.4, 8.2, 9 and 10) over stability, microstructure and tensile mechanical behavior of acellular pericardial matrix was studied. The cross-linking index increased up to 81% while the denaturation temperature increased up to 12 °C after PUP crosslinking. PUP-treated scaffold resisted the collagenase degradation (0.167 ± 0.14 mmol/g of liberated amine groups vs. 598 ± 60 mmol/g for non-cross-linked matrix). The collagen fiber network was coated with PUP while viscoelastic properties were altered after cross-linking. The treatment of the pericardial scaffold with PUP allows (i) different densities of cross-linking depending of the process parameters and (ii) tensile properties similar to glutaraldehyde method. 相似文献
32.
Daniela López‐Araujo Antonio Loría Arturo Zavala‐Río 《International Journal of Adaptive Control and Signal Processing》2017,31(3):299-313
We solve the simultaneous closed‐loop identification and tracking‐control problems for fully‐actuated Euler–Lagrange systems under input constraints. We use a nonlinear adaptive controller reminiscent of computed‐torque‐type controllers in which linear correction terms are saturated in order to comply with the imposed bounds on the control inputs. Adaptation, reminiscent of gradient methods, is used also with saturation. With respect to related literature, our contribution consists in establishing uniform global asymptotic stability. Therefore, our control scheme ensures robustness with respect to bounded perturbations and uniform convergence of the estimation errors for any initial conditions. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
33.
Yuri Torres Arturo Gonzalez-Escribano Diego R. Llanos 《The Journal of supercomputing》2013,65(3):1150-1163
The choice of thread-block size and shape is one of the most important user decisions when a parallel problem is written for any CUDA architecture. The reason is that thread-block geometry has a significant impact on the global performance of the program. Unfortunately, the programmer has not enough information about the subtle interactions between this choice of parameters and the underlying hardware. This paper presents uBench, a complete suite of micro-benchmarks, in order to explore the impact on performance of (1) the thread-block geometry choice criteria, and (2) the GPU hardware resources and configurations. Each micro-benchmark has been designed to be as simple as possible to focus on a single effect derived from the hardware and thread-block parameter choice. As an example of the capabilities of this benchmark suite, this paper shows an experimental evaluation and comparison of Fermi and Kepler architectures. Our study reveals that, in spite of the new hardware details introduced by Kepler, the principles underlying the block geometry selection criteria are similar for both architectures. 相似文献
34.
35.
The influence of fatty acid composition on formation of new compounds at frying temperatures has been studied in seven samples of sunflower oils widely differing in their fatty acid composition. Thermal oxidation assays as well as frying experiments were carried out and samples were evaluated by measuring the new compounds formed, i.e. polymers, polar compounds and their distribution by molecular weight, and polar fatty acids and their distribution by molecular weight. The levels of all the new compounds analysed strongly depended on the degree of oil unsaturation; the two least unsaturated oils with low content of linoleic acid and high content of palmitic acid behaved exceptionally well. When considering polar compounds or polar fatty acids, the polymers/oxidised monomers ratio increased significantly as the level of degradation increased. The new compounds formed are practically identical when analysed in the used frying oils or in the lipids extracted from the counterpart fried potatoes, independently of the level of degradation. 相似文献
36.
Aristides D. Tagalakis Vignesh Jayarajan Ruhina Maeshima Kin H. Ho Farhatullah Syed Lin-Ping Wu Ahmad M. Aldossary Mustafa M. Munye Talisa Mistry Olumide Kayode Ogunbiyi Arturo Sala Joseph F. Standing Seyed M. Moghimi Andrew W. Stoker Stephen L. Hart 《Advanced functional materials》2021,31(37):2104843
37.
The paper considers a network of agents with multiple‐integrator internal dynamics, which share partial information on their states according to an arbitrary topology. For this system, two control problems are addressed and solved. The first consists in assigning the dominant closed‐loop poles. The second consists in achieving a specified consensus with arbitrary dominant dynamics. In both cases, the regulator is required to be decentralized, and the controlled network has to result tolerant with respect to faults in the communication apparatuses of the agents. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
38.
Utilization of ramon seeds (Brosimum alicastrum swarts) as a new source material for thermoplastic starch production
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Carlos Rolando Ríos‐Soberanis Raciel Javier Estrada‐León Víctor Manuel Moo‐Huchin María José Cabrera‐Sierra José Manuel Cervantes‐Uc Luis Arturo Bello‐Pérez Emilio Pérez‐Pacheco 《应用聚合物科学杂志》2016,133(47)
The development and characterization of biodegradable polymers deriving from renewable natural sources has attracted much attention. The aim of this work was to partially characterize a thermoplastic starch obtained from the starch of seeds from the ramon tree (TPS‐RS) as an option to substitute thermoplastic starch from corn (TPS‐CS), in some of its applications. At 55% of relative humidity (RH), TPS‐RS had higher tensile strength and deformation than TPS‐CS. X‐ray diffraction analysis showed similar values in residual crystallinity (percentage of crystallinity that remains after plasticization process) in both TPS. The SEM micrographs showed a few remnant granular structures in the TPS‐RS. The FTIR showed a greater intensity in band at 1016 cm?1 in the TPS‐CS and TPS‐RS in comparison with their corresponding native starch, indicating an increase in the amorphous region after plasticization. The TGA analysis showed greater thermal stability in TPS‐CS (340 °C) compared with TPS‐RS (327 °C). In addition, the glass transition temperature in both TPS was 24 °C. The results obtained represent a starting point to potentialize the use of TPS‐RS instead of TPS‐CS for the development of new biodegradable materials for practical applications in different areas. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44235. 相似文献
39.
Inhibition of Hydroperoxy-, Keto- and Hydroxy-FAME by Alpha- and Delta-Tocopherol at Rancimat Conditions
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Susana Marmesat Arturo Morales M. Victoria Ruiz-Méndez Gloria Márquez-Ruiz Joaquín Velasco 《Journal of the American Oil Chemists' Society》2016,93(1):93-103
The effects of α‐ and δ‐tocopherol on inhibition of hydroperoxides, keto and hydroxy compounds under Rancimat conditions, i.e. 100 °C and air bubbling, were studied in samples of fatty acid methyl esters (FAME) obtained from high linoleic (HL) and high oleic (HO) sunflower oils. Primary hydroperoxides from methyl linoleate and methyl oleate and secondary keto and hydroxy compounds derived from methyl linoleate hydroperoxides were analyzed by HPLC–UV‐ELS. Different tocopherol concentrations, namely, 10, 50, 100, 500 and 1000 mg/kg, were tested. Irrespective of the lipid substrate and the initial concentration of tocopherol, results showed that the content of hydroperoxides accumulated during the induction period was remarkably higher in the samples containing δ‐tocopherol. The relative concentrations of oleate hydroperoxides in the HO samples were also higher in the presence of δ‐tocopherol. α‐Tocopherol was more effective in inhibiting hydroperoxides at low levels, with 100 mg/kg as optimal concentration, while δ‐tocopherol displayed optimal protection at 1000 mg/kg. Under the oxidation conditions applied, neither α‐ nor δ‐tocopherol showed a protective effect on hydroperoxide decomposition at any level assayed. Formation of keto‐ and hydroxy‐dienes was more related to the concentration of their hydroperoxide precursors. Furthermore, both tocopherols gave rise to increased concentrations of ketodienes at 500 and 1000 mg/kg compared to the controls. Such an effect was more pronounced for α‐tocopherol and in the HL samples. 相似文献
40.
Arturo J. Fernández Carlos J. Pérez-González 《The International Journal of Advanced Manufacturing Technology》2016,86(1-4):723-735
Nowadays, as low defect rates per item are often expected in practice, conventional single sampling for lot acceptance purposes is rendered inefficient or unduly expensive. For specific producer’s and consumer’s quality and risk requirements, resubmitted lot sampling usually needs, on the average, less inspection effort than single sampling to properly discriminate between satisfactory and unsatisfactory batches. An integer nonlinear programming problem is stated in order to determine the optimal resubmitted lot sampling plan based on defect count data with limited producer and consumer risks. Nonaccepted lots may be resubmitted for sampling inspection a certain number of times. The number of nonconformities per sampled unit is assumed to follow a Poisson distribution. Quasi-optimal inspection schemes for screening submitted lots of manufactured material are derived in closed-forms by using a normal approximation of the incomplete gamma ratio function. Explicit and quite accurate approximations of the smallest number of units to be tested per lot and the maximum tolerable number of nonconformities in the selected sample are presented. The number of resubmissions with minimal inspection effort and controlled risks is also computed. An application to the manufacturing of glass is provided for illustrative purposes. 相似文献