Recent advances in swollen-state NMR spectroscopy for the study of drying oils     

Giacomo Cipriani  Antonella Salvini  Luigi Dei  Azzurra Macherelli  Francesco Saverio Cecchi  Carlo Giannelli 《Journal of Cultural Heritage》2009,10(3):388-395

The cross-linking processes of three drying oils (poppy, linseed, walnut), a class of organic compounds very important in the field of artworks, were studied by means of ¹H-NMR spectroscopy, following the change of the protons signals when oils are heated at 60 °C in the presence of air or nitrogen gas. This preliminary information is particularly important to identify the presence of drying oils within a solid painting film. We demonstrated that it was possible to study these films by swollen-state NMR, an innovative spectroscopy method that can directly analyze very small semisolid samples instead of solutions. The main advantages of this method are the short time of analysis, the possibility to analyze samples without any preliminary treatment, and the small quantity of the sample required. Therefore, swollen-state NMR technique was used to characterize three real painting films: in this way, we succeeded in recognizing in real paintings specimens the presence of drying oils employed as binders, avoiding any interferences due to other organic compounds acting as binding agents, like waxes or egg-yolk media.  相似文献   

Is microrheometry affected by channel deformation?     

Francesco Del Giudice  Francesco Greco  Paolo Antonio Netti  Pier Luca Maffettone 《Biomicrofluidics》2016,10(4)

Microrheometry is very important for exploring rheological behaviours of several systems when conventional techniques fail. Microrheometrical measurements are usually carried out in microfluidic devices made of Poly(dimethylsiloxane) (PDMS). Although PDMS is a very cheap material, it is also very easy to deform. In particular, a liquid flowing in a PDMS device, in some circumstances, can effectively deform the microchannel, thus altering the flow conditions. The measure of the fluid relaxation time might be performed through viscoelasticity induced particle migration in microfluidics devices. If the channel walls are deformed by the flow, the resulting measured value of the relaxation time could be not reliable. In this work, we study the effect of channel deformation on particle migration in square-shaped microchannel. Experiments are carried out in several PolyEthylene Oxyde solutions flowing in two devices made of PDMS and Poly(methylmethacrylate) (PMMA). The relevance of wall rigidity on particle migration is investigated, and the corresponding importance of wall rigidity on the determination of the relaxation time of the suspending liquid is examined.  相似文献   

Are School-Provided Skills Useful at Work? Results of the Wiles Test     

Liwiński  Jacek  Pastore  Francesco 《Research in higher education》2021,62(1):72-97

Research in Higher Education - We test for the signaling hypothesis versus the human capital theory using the Wiles test in a country which has experienced a dramatic increase in the supply of...  相似文献   

Accuracy between optical and inertial motion capture systems for assessing trunk speed during preferred gait and transition periods     

Martin Kokholm Fleron  Niels Christian Hauerbach Ubbesen  Francesco Battistella  David Leandro Dejtiar 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(4):366-377

Motion capture through inertial sensors is becoming popular, but its accuracy to describe kinematics during changes in walking speed is unknown. The aim of this study was to determine the accuracy of trunk speed extracted using an inertial motion system compared to a gold standard optical motion system, during steady walking and stationary periods. Eleven participants walked on pre-established paths marked on the floor. Between each lap, a 1-second stationary transition period at the initial position was included prior to the next lap. Resultant trunk speed during the walking and transition periods were extracted from an inertial (240 Hz sampling rate) and an optical system (120 Hz sampling rate) to calculate the agreement (Pearson’s correlation coefficient) and relative root mean square errors between both systems. The agreement for the resultant trunk speed between the inertial system and the optical system was strong (0.67 < r ≤ 0.9) for both walking and transition periods. Moreover, relative root mean square error during the transition periods was greater in comparison to the walking periods (>40% across all paths). It was concluded that trunk speed extracted from inertial systems have fair accuracy during walking, but the accuracy was reduced in the transition periods.  相似文献   

Protective action against fungal growth of two consolidating products applied to wood     

Marina Clausi  Gino Mirocle Crisci  Mauro Francesco La Russa  Marco Malagodi  Annamaria Palermo  Silvestro Antonio Ruffolo   《Journal of Cultural Heritage》2011,12(1):28-33

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Indirect estimation of injected mortar volume in historical walls using the electrical resistivity tomography     

Nasser Abu Zeid  Marco Balducci  Francesco Bartocci  Roberto Regni  Giovanni Santarato 《Journal of Cultural Heritage》2010,11(2):220-227

The electrical resistivity tomography (ERT) represents one of the widely used geophysical techniques for the exploration of the subsurface. In the last few years, this method has been demonstrated to be an efficient reconnaissance tool not only for monitoring degradation status of walls and foundations of historical buildings, but also for imaging the spatial distribution of injected mortar, commonly employed for consolidation purposes. A 3D resistivity tomography survey was carried out on four selected wall portions of the historical church of Montepetriolo, Perugia, Central Italy. The obtained 3D resistivity distribution models before and after grouting provided suggestive images of the internal structure of the studied walls. Moreover, the spatial distribution of the zones being filled with mortar was determined quantitatively by scaling the post- to the preinjection resistivity values. Using a well known correlation between resistivity and porosity, established in the geophysical community, a further step towards a more quantitative assessment was attempted to indirectly determine the unit volumes of the injected mortar The obtained results were satisfactory and in some cases almost similar to the yard data. Furthermore, two flat-jack tests confirmed the local increment of the mechanical resistance of the studied left front (2) and right lateral (3) wall portions.  相似文献   

Foundational skills and dispositions for learning: an experience with Information Problem Solving on the Web     

Francesco Caviglia 《Technology, Pedagogy and Education》2016,25(4):487-512

Active participation in the information society requires the ability to find some order in the chaotic nature of the Web and not to get lost within the endemic presence of inaccurate, misleading, biased and false information. This article presents an approach to Information Problem Solving (IPS) – that is, finding, understanding and assessing information on the Web – and discusses a study carried out in an Italian secondary school, using an experimental and a control group. The study aimed at exploring how to best foster IPS skills, and observing whether and how IPS activities could promote the development of more general learning dispositions and competences. After a period of training with IPS activities, the experimental group showed different dispositions towards learning from a text and engaging with open-ended questions. Despite serious limitations in the depth of analysis, most students were able to reach acceptable solutions; at the same time, they felt empowered and developed an embryonic critical attitude on which it might be possible to build further.  相似文献   

Agency online: trends in a university learning course     

Maria Beatrice Ligorio  Maria Antonietta Impedovo  Francesco Arcidiacono 《Technology, Pedagogy and Education》2017,26(5):529-543

This article aims to investigate how university students perform agency in an online course and whether the collaborative nature of the course affects such expression. A total of 11 online web forums involving 18 students (N = 745 posts in total) were qualitatively analysed through the use of a codebook composed of five categories (individual, interpersonal, epistemic, transformative and collective) and several sub-categories purposely developed for the sake of this research. The results show that each category follows a specific path, although two events – the re-mixing of the groups and the assumption of the peer-tutor role – particularly affected the evolution of trends. Although this study needs further development, the authors believe that an in-depth understanding of the nature of agency, including how to analyse it as well as empower it when implementing blended educational activities, engages relevant theoretical and pedagogical issues.  相似文献   

Measuring Weathering and Nanoparticle Coating Impact on Surface Roughness of Natural Stones     

Simona Raneri  Jacopo Crezzini  Simona Arrighi  Francesco Boschin  Ilaria Alfieri  Germana Barone 《文物保护研究》2013,58(5):298-309

ABSTRACT

The surface texture of a stone represents a sensitive parameter in evaluating its conservation state. In monuments and sculptures, in fact, external agents continuously alter the appearance of stones, determining peculiar weathering patterns and modifying properties such as retention of water and particles, interaction with light, color, and finishing. The application of protective coatings also determines changes in surface appearance of a stone, usually evaluated and monitored by color change tests. Surface metrology methods offer the possibility to quantify these changes, evaluating the impact of external agents (natural, i.e. weathering, and artificially, i.e. protective coatings) on natural stones. In this research, we demonstrate the potential of surface areal measurements in describing the evolution of weathering processes and the effects of protective treatments on porous stone materials. The obtained results suggest that the extent of the modifications is related to the scale of observation (small- vs. large-scale undulations, i.e. roughness and waviness, respectively), with an overall increase of surface roughness as the weathering proceeds. Unexpectedly, coatings based on nanoparticle dispersions increase the topographic height parameters, due to the absence of a homogeneous film.  相似文献   

Felix Büchel, Andries de Grip and Antje Mertens, Editors, Overeducation in Europe. Current Issues in Theory and Policy, Edward Elgar, Cheltenam, UK (2003) (Xi+239pp., $105.00).     

Francesco Pastore   《Economics of Education Review》2006,25(6):682-683

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