Study of silica nanoparticles – polysiloxane hydrophobic treatments for stone-based monument protection     

Lavinia de Ferri  Pier Paolo Lottici  Andrea Lorenzi  Angelo Montenero  Emma Salvioli-Mariani 《Journal of Cultural Heritage》2011,12(4):356

The growing interest in the conservation of historic buildings encourages the development of water-repellent materials and methodologies to consolidate and/or protect stones. Recently, particular attention was devoted to composites of inorganic oxides nanoparticles and hybrid siloxane or silicone polymers. Here we present a study on the water repellence of a thin protective coating obtained through sol-gel process starting from Glymo and Dynasylan 40®, and loading the silicate matrix with nano-sized silica particles (Aeroxide LE1® -Degussa-Evonik). The coatings were applied to limestone, sandstone and granite samples. The silica nanoparticles have been characterized by XRD, the siloxane matrix through micro-Raman spectroscopy, while the surface morphology was examined by SEM. The efficacy of the treatments has been evaluated through static contact angle measurements and capillary water absorption. The optical appearance of the coatings was evaluated by colorimetric measurements. Nanoparticles at suitable concentration gave high values for the static contact angle (up to ∼ 150°), for all stone species even for four months exposure to atmospheric conditions. The coatings, in the water capillary absorption tests, however, behave as expected only for granite even if the long-term water direct contact reduces the hydrophobicity.  相似文献   

Occupational stereotyping by hearing impaired and hearing people: experiences of a comparative survey     

Marta Zsoldos  Andrea Perlusz 《欧洲特需教育杂志》2013,28(1):111-116

ABSTRACT

The problems of preparing hearing impaired people for adult life and for productive work have not yet been properly solved in Hungary. The main reasons can be found in the old tradition of segregated education for people with disabilities. The political changes of 1990 and the economic reforms have not brought about any favourable changes. A nationwide, comparative survey dealing with vocational prejudices and attitudes concerning hearing persons and hearing impaired persons showed that the vocational knowledge and expectations of the latter group is not satisfactory, their information is uncertain and that they have prejudices against themselves ‐ that is, they suppose that high‐prestige professions are not available to them. Deaf persons are even more prejudiced than hard of hearing persons.  相似文献   

Auswirkungen von körperlicher Aktivität auf demenzielle Erkrankungen     

Andrea Scharpf MA  Sandra Servay  Alexander Woll 《Sportwissenschaft》2013,43(3):166-180

There is evidence for a positive influence of physical activity on dementia. However, the study design and data processing of current studies on physical activity in patients with dementia are heterogeneous, which makes it difficult to evaluate and compare their results. In our review, we categorized the studies based on different aspects of the training interventions and discussed these aspects in detail. Based on the existing literature, the length of an ideal training program is at least 16 weeks with two to three training sessions per week and qualified supervision and instruction. The workout program should contain at least two of the three components strength, endurance and balance. These recommendations should be confirmed in future studies with comparable study designs and homogeneous patient groups.  相似文献   

Search Regimes and the Industrial Dynamics of Science     

Andrea Bonaccorsi 《Minerva》2008,46(3):285-315

The article addresses the issue of dynamics of science, in particular of new sciences born in twentieth century and developed after the Second World War (information science, materials science, life science). The article develops the notion of search regime as an abstract characterization of dynamic patterns, based on three dimensions: the rate of growth, the degree of internal diversity of science and the associated dynamics (convergent vs. proliferating), and the nature of complementarity. The article offers a conceptual discussion for the argument that new sciences follow a different pattern than established sciences and presents preliminary evidence drawn from original data in particle physics, computer science and nanoscience.

Andrea BonaccorsiEmail:

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Early Education for Spatial Intelligence: Why,What, and How     

Nora S. Newcombe  Andrea Frick 《Mind, Brain, and Education》2010,4(3):102-111

Spatial representation and thinking have evolutionary importance for any mobile organism. In addition, they help reasoning in domains that are not obviously spatial, for example, through the use of graphs and diagrams. This article reviews the literature suggesting that mental spatial transformation abilities, while present in some precursory form in infants, toddlers, and preschool children, also undergo considerable development and show important individual differences, which are malleable. These findings provide the basis for thinking about how to promote spatial thinking in preschools, at home, and in children's play. Integrating spatial content into formal and informal instruction could not only improve spatial functioning in general but also reduce differences related to gender and socioeconomic status that may impede full participation in a technological society.  相似文献   

Black power ideology rhetoric and reality in a student sample     

Elise E Lessing  Chester C Clarke  Lisa Gray-Shellberg 《Int J Intercult Relat》1981,5(1):71-94

In America the ethic of individual achievement has always been balanced by complementary norms of group action. Blacks, however, have been handicapped by a lack of the in-group loyalty required for a united struggle against racial oppression. Black power ideology was conceived as a sociotherapy to increase the level of black group cohesion. This study was designed to provide much needed data on the success of the “therapy.” A survey of 611 black high school students and 93 black college students yielded little evidence that verbally professed endorsement of black power ideology was translated into action. In an experiment. 323 black high school students manifested a consistent tendency to be less helpful to scientists identified as black than to unidentified scientists, regardless of the students' claimed level of black power orientation.  相似文献   

Harnessing NASA Goddard’s Grey Literature: The Power of a Repository Framework     

Nikkia Anderson  Gail Hodge  Andrea Japzon 《Publishing Research Quarterly》2007,23(1):58-64

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Afro-American Popular Drama     

Chester J. Fontenot 《Journal of American culture (Malden, Mass. : 2003)》1978,1(1):205-212

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Rats do show primacy and recency effects in memory for lists of spatial locations: A reply to Gaffan     

Raymond P. Kesner  Andrea A. Chiba  Pamela Jackson-smith 《Learning & behavior》1994,22(2):214-218

It has been demonstrated that rats display both primacy and recency effects in list-learning experiments for both item- and order-recognition memory for spatial location information. Contrary to a suggestion made by Gaffan (1992) that previous demonstrations of primacy effects in rats are not valid due to statistical and methodological problems, we show that (1) it is not likely that our results are due to experimenter bias and/or nonindependence of trials, (2) primacy and recency effects are obtained whether or not one uses a training criterion, and (3) when many of the published reports from our laboratory are combined, the number of subjects and trials are sufficient to evaluate the validity of primacy and recency effects in list-learning experiments.  相似文献   

Youth in a suspect society     

Andrea C. Allard 《British Journal of Sociology of Education》2010,31(6):827-834

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