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Calcium hydroxide is typically used in Cultural Heritage conservation for superficial protective treatments thanks to its conversion into calcium carbonate. Calcium carbonate is, in fact, compatible with many carbonate-based architectonic surfaces, because its characteristics are similar to those of the restored materials. In order to improve calcium hydroxide treatments, Ca(OH)2 particles with sub-micrometric dimensions (nanolimes), are synthesised by a chemical precipitation process: a sodium hydroxide solution, used as precipitator, is added, drop by drop, to a calcium chloride one. In this paper, a nanometric calcium hydroxide, to be used in stones treatment, is produced adding in the initial solutions a surfactant agent (Triton X-100); the solutions are then mixed together simultaneously, drastically reducing the time needful for preparation. Different contents of surfactant are employed, and the influence on particles dimension and carbonatation process is analysed too. The obtained Ca(OH)2 nanoparticles are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron diffraction (ED). The Ca(OH)2 nanoparticles are regularly shaped, hexagonally plated and with side dimensions less than 200 nm: in particular, increasing the surfactant content, the particle dimension reaches values until 20 nm. Comparing nanolime suspensions obtained without and with the addition of the surfactant agent, the last ones have comparable, if not better, performances in terms of average particle size and morphology, crystallinity and reactivity. Afterwards, the alcoholic nanolime suspension obtained by using Triton X-100 is applied on some natural stones; in fact, the aim of this section is to compare the obtained results with those achieved using a nanolime synthesised without the surfactant agent. To evaluate the treatment effectiveness in a preliminary way, standard tests are performed and compared with the same tests previously obtained by the nanolime synthesised without the surfactant agent: “Scotch Tape Test” and capillarity test. 相似文献
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Claudio Vezzani Giulia Vettori Giuliana Pinto 《European Journal of Psychology of Education - EJPE》2018,33(4):665-684
Research on students’ conceptions of learning is a growing and complex area of interest in the field of psychology of education. Even though much of the investigation addressed to explore conceptions of learning at the university level, still less research has considered how naïve (i.e. ‘learning as reduction of deficit knowledge through individual effort’) and sophisticated (i.e. ‘learning as opportunity and self-efficacy’) conceptions of learning are related to personal and contextual factors. This research investigated how gender, academic area, and level of study influence university students’ conceptions of learning. Three hundred forty-six university students participated in the study. They were either from humanities (240) or technical-scientific (106) areas of study and they were attending either a Bachelor (140) or Master’s degree (206) course. Conceptions of learning were explored using a self-report instrument (Learning Conceptions Questionnaire; LCQ). A MANOVA revealed that females show conceptions of learning more related to social and motivational aspects of learning with a greater personal involvement, compared with males. No typical pattern of conceptions of learning was found for humanities students or for technical-scientific students. Increasing with the level of study, students showed both naïve and sophisticated conceptions of learning increased, since both ‘learning as reduction of deficit knowledge through individual effort’ and ‘learning as opportunities and self-efficacy’ were more likely. Implications of these results and future lines of research will be discussed. 相似文献
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Lucia Bigozzi Giuliana Pinto Renato Donfrancesco 《International Journal of Disability, Development & Education》2016,63(4):450-466
Several studies have explored the relationship between dyslexia and creativity, but results have been rather mixed. This study examines whether Italian dyslexic children are more creative than their peers without a reading impairment. One hundred ninety Italian children aged between 9 and 13 participated in this study, divided into two groups: Ninety five dyslexic students and ninety five peers without a reading impairment. All the participants’ creativity skills were assessed. The results indicated that dyslexic children outperformed their peers in the total score, and in the originality, elaboration, and titles sub-scores, whereas no differences were found in the fluency and flexibility sub-scores. The results are discussed in relation to the practical implications, and provide indications for supportive learning environments. 相似文献
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Using data from the third UK Community Innovation Survey we model the usage of e-business across and within firms in the UK in the year 2000 as a single observation upon an integrated process of inter- and intra-firm diffusion. The intra-firm dimension is a significant extension to standard analysis. The model estimates indicate that the pattern of e-business usage reflects the heterogeneity of firms in terms of size, other innovative activity and labour force skills (generating differences in the payoffs to use) as well as market and non-market intermediated externalities. The policy implications of the findings are discussed. 相似文献