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81.
82.
Adrian V. Catalina Subhayu Sen Doru M. Stefanescu 《Metallurgical and Materials Transactions A》2003,34(2):383-394
The Jackson and Hunt (JH) theory has been modified to relax the assumption of isothermal solid/liquid interface used in their
treatment. Based on the predictions of this modified theory, the traditional definitions of regular and irregular eutectics
are revised. For regular eutectics, the new model identifies a range of spacing within the limits defined by the minimum undercooling
of the α and β phases. For the irregular Al-Si eutectic system, two different spacing selection mechanisms were identified: (1) for a particular
growth rate, a nearly isothermal interface can be achieved at a unique minimum spacing λ
I
; (2) the average spacing (λ
av
>λ
I
) is essentially dictated by the undercooling of the faceted phase. Based on the modified theoretical model, a semiempirical
expression has been developed to account for the influence of the temperature gradient, which is dominant in the irregular
Al-Si system. The behavior of the Fe-Fe3C eutectic is also discussed. The theoretical calculations have been found to be in good agreement with the published experimental
measurements. 相似文献
83.
Lizbeth Escobedo Catalina Ibarra Jehu Hernandez Mariana Alvelais Monica Tentori 《Personal and Ubiquitous Computing》2014,18(6):1485-1497
Teachers spend considerable amount of time keeping students with autism “on task” giving away prompts and rewards and maintaining a detailed record of students’ progress during the object discrimination training. We hypothesize that tangible computing, in particular smart objects, could help teachers cope with the problems faced during the object discrimination training of students with autism. In this paper, we describe design principles for smart objects to support the object discrimination training and present several example prototypes. First, we present the design and implementation of “Things that think” (T3), a smart device that converts traditional objects into smart objects that promote interactivity with a playful and engaging interaction, and are capable of the automatic recording of students’ progress. Then, we present four T3 smart objects assembled in a board. The results of a 7-week deployment study of the use of such smart objects in three classrooms of students with autism (n = 25, 7 teachers and 18 students with autism) demonstrate T3 smart objects reduce the workload of teachers, ease the record-keeping and increase its reliability, and reduce students’ behavioral problems while improving their cognitive efficacy. We close discussing directions for future work. 相似文献
84.
Hydrophobically modified water‐soluble polymers have been prepared by copolymerization of 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) and isodecyl methacrylate (iDMA) in N,N‐dimethylformamide under nitrogen atmosphere, varying the composition feed. Fluorescence spectroscopy was used to further confirm the copolymers self‐aggregate in water. Critical concentration of the self‐aggregate formation (CAC) decreased by increasing the molar fraction of iDMA in the AMPSco copolymers and varied between 1.20 and 0.04 g/L depending on the degree of hydrophobic modification. Hence, copolymer composition and charge density allowed tuning the pseudomicellar characteristics of these new amphiphilic copolymers. The addition of a salt or a low‐molecular‐weight surfactant was studied. Binding of CTAB to the AMPSco copolymers leads to a high decrease of CAC, i.e., 0.006 g/L. Effect of the composition in the viscosimetric behavior of the hydrophobically modified copolymers AMPSco was investigated. The removal of single metal ions, Cu2+, and m‐cresol from aqueous solutions by ultrafiltration with the help of the copolymers was investigated. Equilibrium dialysis experiments demonstrate that the formation of hydrophobic microdomains can be used to control the sequestration of foulants, and thus these novel copolymers have potential application as polymeric surfactants in micellar‐enhanced ultrafiltration processes for water purification. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
85.
Maria Catalina Hernandez-Rodas Rodrigo Valenzuela Luis A. Videla 《International journal of molecular sciences》2015,16(10):25168-25198
Non-alcoholic fatty liver disease (NAFLD) is the main cause of liver disease worldwide. NAFLD is linked to circumstances such as type 2 diabetes, insulin resistance, obesity, hyperlipidemia, and hypertension. Since the obesity figures and related comorbidities are increasing, NAFLD has turned into a liver problem that has become progressively more common. Currently, there is no effective drug therapy for NAFLD; therefore, interventions in lifestyles remain the first line of treatment. Bearing in mind that adherence rates to this type of treatment are poor, great efforts are currently focused on finding novel therapeutic agents for the prevention in the development of hepatic steatosis and its progression to nonalcoholic steatohepatitis and cirrhosis. This review presents a compilation of the scientific evidence found in the last years showing the results of interventions in lifestyle, diet, and behavioral therapies and research results in human, animal and cell models. Possible therapeutic agents ranging from supplementation with vitamins, amino acids, prebiotics, probiotics, symbiotics, polyunsaturated fatty acids and polyphenols to interventions with medicinal plants are analyzed. 相似文献
86.
Mara V. Galmarini Catalina van Baren María C. Zamora Jorge Chirife Paola Di Leo Lira Arnaldo Bandoni 《International Journal of Food Science & Technology》2011,46(7):1337-1345
Trehalose was studied as a drying aid to establish its impact on aroma retention in freeze dried strawberry puree. The evaluation was done by sensory analysis and headspace‐solid phase microextraction‐gas chromatography with a mass detector (HS‐SPME‐GC‐MS); results were compared with those obtained using sucrose and maltodextrin (MD) as drying aids. The carbohydrate used significantly modified the type and concentration of volatiles retained during freeze drying. HS‐SPME‐GC‐MS outcomes showed that the use of trehalose (alone or with MD) resulted in the product with the chromatographic profile most similar to fresh strawberry puree, being different from sucrose and MD. Meanwhile, sensory analysis showed a similarity with the aromatic profiles when using trehalose or sucrose, remaining both different from MD. This study proved that the use of trehalose as a drying aid can be beneficial on volatile aroma retention and that different combinations of organic volatiles can lead to similar sensory profiles. 相似文献
87.
Aaron D. Ratschow María Catalina Bermúdez Agudelo Manfred J. Hampe 《International Journal of Hydrogen Energy》2021,46(21):11926-11939
A three-dimensional, non-isothermal, steady state model for stacks of tubular high temperature proton exchange membrane fuel cells (HT PEM FCs) is developed. It is based on a thin layer approach for the membrane-electrode assembly while retaining Butler-Volmer kinetics, concentration and Ohmic losses on both electrodes. It solves for flow, temperature and concentration fields as well as locally resolved current densities for multiple cells. Single cell results for the polarization curve compare well with experimental data for single tubular HT PEM FCs. The model allows for efficient simulations of stacks of multiple tubular HT PEM FCs with a shared air channel in which the interactions between local FC performance and flow, temperature and concentration fields pose a major design challenge. The effects of flow field design, flow rate and cell distance in a stack of 7 tubular cells are investigated and basic approaches for the design of such stacks are derived. 相似文献
88.
89.
Pouria Sayyad Khodashenas Jaume Comellas Salvatore Spadaro Jordi Perelló 《Photonic Network Communications》2013,26(2-3):131-139
Elastic optical network technologies arise as promising solutions for future high-speed optical transmission, since they can provide superior flexibility and scalability in spectrum allocation toward the seamless support of diverse services along with the rapid growth of Internet traffic. In elastic optical networks, heterogeneous traffic demands are typically supported by a single type of bandwidth-variable transmitters, which is not always spectrum and cost-efficient. In light of this, the aggregation of same source but different destination subwavelength connections has been recently introduced for elastic optical networks, aiming to obtain both transmitter and spectrum usage savings. In this paper, we propose a novel algorithm for dynamic source aggregation of connections. Moreover, we introduce a novel node architecture enabling the realization of the proposed source aggregation in a cost-effective way. The obtained results demonstrate considerable improvement in the network spectrum utilization, as well as a significant reduction in the number of necessary transmitters per node. 相似文献
90.