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51.
Przemyslaw B. Kowalczuk Marta Siedlarz Sabina Szczerkowska Marta Wojcik 《分离科学与技术》2018,53(8):1198-1206
ABSTRACTIn this work, a facile method for determination of foaming properties of frothers was used. It was based on measuring the foam height in a flotation machine at different concentrations of frothers. Based on the foam height-concentration curve, a new foaming parameter, so-called concentration at half of the maximum foam height CMH, was proposed. Assessment and usefulness of CMH were shown in flotation of quartz. The concentration of amine at the critical contact angle CCA, at which amine starts to be a collector, was also determined. The determined values of CCA were similar to CMH and were equal to 1.3, 0.14 and 0.03 mM for ButNH2, HexNH2 and OctNH2, respectively. The values of CMH and CCA depended on the alkyl chain of frothers. 相似文献
52.
R. Guinovart-Díaz R. Rodríguez-Ramos J. C. López-Realpozo J. Bravo-Castillero J. A. Otero F. J. Sabina F. Lebon S. Dumont 《Acta Mechanica》2016,227(1):57-73
In most composites, the fiber–matrix adhesion is imperfect; the continuity conditions for stresses and displacements are not satisfied. In this contribution, effective elastic moduli are obtained by means of the asymptotic homogenization method (AHM), for three-phase fibrous composites (matrix/mesophase/fiber) with parallelogram periodic cell. Interaction between fiber and matrix is considered, and this is called the mesophase model where the nonuniform mesophase is studied. Besides, there is another type of matrix–fiber contact which is called nonuniform spring imperfect contact. In this case, the contrast or jump of the displacements in the boundary of each phase is proportional to the corresponding component of the tension in the interface in terms of a parameter given by a certain function that depends on the position. The constituents of the composites exhibit transversely isotropic properties. A doubly periodic parallelogram array of cylindrical inclusions under longitudinal shear is considered. The three-phase model is validated by the Finite Element Method and the AHM both approaches applied to two-phase composites with nonuniform spring imperfect contact. Comparisons with theoretical and experimental results verified that the present model is efficient for the analysis of composites with presence of nonuniform imperfect interface and parallelogram cell. The effect of the nonuniform imperfection on the shear effective property is observed. The present method can provide benchmark results for other numerical and approximate methods. 相似文献
53.
54.
The article is concerned with the preparation of polymer–iron oxide nanocomposites and the study as drug‐delivery matrices under the influence of applied magnetic field. Biocompatible materials were prepared by incorporating an aqueous ferrofluid in poly(vinyl alcohol) and scleroglucan (SCL) hydrogels, loaded with theophylline as model drug for release studies. The in vitro release profile was obtained using a flat Franz cell and the kinetic parameters were derived applying a semiempirical power law. A magnetic characterization of nanoparticles contained in the ferrofluid was performed by obtaining the magnetization curve. For both systems, the observed drug release profiles decreased when a uniform external magnetic field is applied suggesting they can be used as environmental responsive matrices for biomedical applications. Dynamic rheological measurements show that a higher storage modulus and a more compact structure are obtained by incorporating the ferrofluid into the hydrogels. These rheological results and environmental electron scanning microscopy micrographs point to an understanding of release behavior once the magnetic field is applied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
55.
Development of a membraneless ethanol/oxygen biofuel cell 总被引:1,自引:0,他引:1
Sabina Topcagic 《Electrochimica acta》2006,51(11):2168-2172
Biofuel cells are similar to traditional fuel cells, except the metallic electrocatalyst is replaced with a biological electrocatalyst. This paper details the development of an enzymatic biofuel cell, which employs alcohol dehydrogenase to oxidize ethanol at the anode and bilirubin oxidase to reduce oxygen at the cathode. This ethanol/oxygen biofuel cell has an active lifetime of about 30 days and shows power densities of up to 0.46 mW/cm2. The biocathode described in this paper is unique in that bilirubin oxidase is immobilized within a modified Nafion polymer that acts both to entrap and stabilize the enzyme, while also containing the redox mediator in concentrations large enough for self-exchange based conduction of electrons between the enzyme and the electrode. This biocathode is fuel tolerant, which leads to a unique fuel cell that employs both renewable catalysts and fuel, but does not require a separator membrane to separate anolyte from catholyte. 相似文献
56.
Sabina Scarpellini Alfonso Aranda Juan Aranda Eva Llera Miguel Marco 《Clean Technologies and Environmental Policy》2012,14(6):1047-1058
It is widely accepted that eco-innovation is the direction to make progress towards a sustainable innovation. Public and private actors seem to share a common point of view and agreement on the benefits of implementing eco-innovation. If this is the case, why eco-innovative activities are still exceptional and exemplary instead of being the usual reasoning and inspiring driver for all kind of actions? Going in depth into the reasons why eco-innovation techniques are not broadly spread, the main one is the lack of internalization of this attitude in all the everyday actions taken by companies and employees in the form of social responsibility. Definitively, society as a whole is responsible for the eco-innovation promotion. Large companies have long ago incorporated Social Responsibility into their strategic planning and invest on innovation as a competitive advantage. However, they are reluctant to contribute to the eco-innovation. Therefore, universities and technology centers (TCs) have to play this role and link the private sector, specially medium, and small size companies, with the society needs. However, Universities are not often leading the eco-innovation initiative. Currently, in the case of Spain, it is observed a huge gap between the scientific research efforts made by the Public University and the academic offering and the real needs of the private companies. In fact, mixed structures as TCs are needed in order to overcome this disconnection, increasing opportunities for subsequent cooperation in eco-innovation projects. This paper points out the causes of the Spanish R&D and innovation lag, and highlights the reasons of the disconnection between public and private research for innovation, while giving hints on what is working fine and what needs to be reviewed to catch up with the R&D reference countries in Europe. 相似文献
57.
Extraction of α‐glucosidase inhibitory compounds from Phaleria macrocarpa fruit flesh using solvent,sonication, and subcritical carbon dioxide soxhlet methods
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58.
Ewelina Basiak Sabina Galus Andrzej Lenart 《International Journal of Food Science & Technology》2015,50(2):372-380
Composite films prepared by casting wheat starch and whey‐protein isolate at proportions of 100–0%, 75–25%, 50–50%, 25–75% and 0–100% were characterised. Combination of both substances gave continuous and homogeneous films. The more the starch is in a film, the more dull is the appearance. The highest water adsorption was observed for pure whey‐protein films and the lowest for pure wheat starch films with the final water content of 0.264 and 0.324 g water g d.m.?1, respectively. An exponential equation well fitted the experimental data of water vapour kinetics (R2 ≥ 0.99). The highest values of thickness and elongation at break were observed for films obtained by blending of wheat starch and whey protein. With the increasing content of whey‐protein isolate, the values of the swelling index and tensile strength increased from 34.31% to 71.01% and from 2.29 to 8.90 MPa, respectively. The values of water vapour permeability depended on humidity conditions and decreased slightly with the increasing content of whey‐protein isolate. 相似文献
59.
Giuseppe Papa Antonino Romano Donato Quaratino Marina Di Fonso Marinella Viola Maria Cristina Artesani Sabina Sernia Mario Di Gioacchino Alberto Venuti 《The Science of the total environment》2001,270(1-3)
In the last few years Cupressus sempervirens has been identified as the cause of an increasing number of cases of late winter-early spring pollinosis in Mediterranean countries. We conducted a 4-year retrospective study of a large group of subjects with documented allergic respiratory disease in order to determine the prevalence, clinical significance and annual rate of sensitization to C. sempervirens pollen. Anamnestic data and skin prick tests (SPT) with common aeroallergens and C. sempervirens extract were collected from 1397 subjects (712 male and 685 female) resident in Latium, a region in central Italy, with complaints related to upper- or lower-respiratory-tract disorders or conjunctival disease. Two hundred and forty-three subjects (17.4%) showed positive results to C. sempervirens extract; 47 (19.3%) of them were monosensitized. The annual sensitization rate of SPT positivity to C. sempervirens varied from 7.2% in 1995 to 22% in 1998. All the subjects monosensitized to cypress pollen had symptoms from January through April. Our study suggests that sensitivity to C. sempervirens is responsible for respiratory symptoms in an increasing percentage of subjects. Further studies are needed to determine its frequency at the national level. 相似文献
60.
Catia Arbizzani Sabina BeninatiMariachiara Lazzari Francesca SoaviMarina Mastragostino 《Journal of power sources》2007
The use of ionic liquid (IL) electrolytes is a promising strategy to enhance the performance of supercapacitors above room temperature. In this paper we present the results of a study on optimization of electrode materials for IL-based supercapacitors featuring a hybrid configuration with carbon negative electrode and poly(3-methylthiophene) (pMeT) as positive operating at 60 °C with the ILs N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) and 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI). As it concerns the carbon electrode two routes have been pursued: (i) surface modification of commercial activated carbon and (ii) synthesis of mesoporous cryo- and xerogel carbons. Pore size distribution and electrochemical characterization data are related and suggest that the second route should be the most promising for carbons of high specific capacitance and low time constant in IL. For the polymer electrode the nature of the galvanostatic polymerization bath plays a crucial role to provide pMeT of high specific capacitance and the best results may be obtained when pMeT is electropolymerized in the same IL used for the capacitance tests. The strategy of using the acid additive trifluoromethanesulfonimide in IL-based polymerization baths is also described in some detail. This strategy that provides pMeT featuring more than 200 F g−1 in IL is a clean procedure which prevents consumption of the ionic liquid with great advantage in terms of costs. 相似文献