1,720,974 research outputs found
Solid-state transformation of (NH4, Ba)-clinoptilolite to monocelsian, mullite, and cristobalite
No full textThree clinoptilolite-based materials, with Ba2+/NH4+ ratios of 2.27, 0.60 and 0.11, were prepared starting from a powder containing about 90% of NH4-clinoptilolite. The samples were submitted to thermal treatments of 2 h up to 1200 °C. Further treatments were carried out at 1100 and 1200 °C for 4, 8, 16 and 32 h. The sequence of reactions observed in heating (NH4, Ba)-clinoptilolite is: dehydration; de-ammoniation (along with residual dehydration); dehydroxylation; amorphization; crystallization of new phases. Amorphization temperature varied from 700 to 900 °C, and increased with barium content. Monocelsian, mullite and cristobalite/tridymite were obtained from all samples heated 32 h at 1100 °C, along with residual glass that never exceeded 9%. The Ba2+/NH4+ ratio resulted the main factor in determining type and quantity of the phases formed in the fired products, as well as their order of crystallization, but also temperature and duration of treatment affected the result. At 1100 °C mullite crystallized as last phase in the Ba-rich sample, and it did not form at 1200 °C. Similarly, celsian was never obtained at 1200 °C from the ammonium-rich material, and was the last phase to crystallize at 1100 °C. Transformations were faster at 1200 °C, but the amounts of residual glass were higher. Hexacelsian, the metastable polymorph of Ba-feldspar which is always formed during the heating of Ba-exchanged zeolites A and X, was never recorded among crystallization products obtained from (NH4, Ba)-clinoptilolite
Self-esteem and mood in obese children and their mothers: A pilot study
Get PDFObjective: A test-retest pilot study was conducted to examine the relationship between overweight/obesity, self-esteem and mood in a group of school-age children, and the degree to which they changed after a tailored psycho-educational intervention. Before and after administering the psycho-educational training, the following aspects were assessed: the child's weight (BMI); the child's and mother's levels of self-esteem and mood; the mother's perception of their child; and the child's general quality of life. Method: Subject to their prior informed consent, 12 overweight/obese children aged between 8 and 13 years, and their mothers were involved in a psycho-educational intervention, which consisted in four meetings with both the children and their mothers. The study consisted in measuring anthropometric parameters and administering specific psychological tests (the CDI, TMA, BDI, B-SE, and CBCL) to both the children and their mothers before and after the psycho-educational intervention. Results: The results showed that a high BMI was associated with depressive symptoms (anhedonia, negative mood) and low self-esteem (family life, body experience). Low levels of self-esteem were also found in 50% of the mothers, with no correlations between the mother's and child's self-esteem. On analyzing the mothers' clinically significant depressive symptoms (cognitive-affective sphere), it emerged that they included the perception of more problems in their child. After the psycho-educational intervention, there were improvements in: the children's BMI; the children's depressive symptoms and self-esteem; the mothers' depressive symptoms and self-esteem; and the mothers' perceptions of their child's problems. Conclusions: Our case series confirmed the association between overweight/obesity and psychological issues. Overweight/obese children need to be also addressed regarding the psychological fallout of their physical condition. Any intervention must also include the parents, to make them more aware, more committed, and better able to help their child change
Thermal Transformation of NH4-Clinoptilolite to Mullite and Silica Polymorphs
No full textClinoptilolite is a natural zeolite used for the abatement of ammonium in the treatment of urban wastewater. By considering that mullite was obtained through thermal treatment of NH4-exchanged synthetic zeolites, this work aimed to evaluate if this phase can be obtained from NH4-clinoptilolite. A material containing about 90 wt % of clinoptilolite, prepared using a Sardinian zeolite-rich rock, was NH4-exchanged and subjected to treatments up to 1200 °C. After dehydration, de-ammoniation, and dehydroxylation processes, the clinoptilolite structure collapsed at 600 °C. An association of mullite, silica polymorphs, and glass, whitish in color, was obtained for treatments between 1000 and 1200 °C. The higher degree of crystallinity was reached after a 32 h heating at 1100 °C: mullite 22 wt %, cristobalite 59 wt %, tridymite 10 wt %, glass 9 wt %. It is possible to speed up the kinetics of the transformation by increasing the temperature to 1200 °C, obtaining the same amount of mullite in 2 h, but increasing the residual amorphous fraction (16 wt %). These results indicate that NH4-clinoptilolite could represent a raw material of potential interest in the ceramic field, in particular in the production of acid refractory, opening scenarios for a possible reuse of clinoptilolite-based exchangers employed in ammonium decontamination
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
The Impact of The Covid-19 Pandemic on Adolescent Neuropsychiatric Admissions for Anorexic Eating Disorders Throughout the 2013-2022 Decade
Get PDFObjective: The purpose of this study is to evaluate the impact that Covid-19 pandemic and the related restrictive measures have had on minors diagnosed with eating disorders (EDs), in particular Anorexia nervosa (AN) and restrictive unspecified EDs, both on an epidemiological and on a clinical level.Methods: We considered AN and restrictive unspecified EDs cases treated in the years 2013-2022 in Padua Hospital’s Child Neuropsychiatry ward, the 97 patients were then divided into two groups, one dated before the pandemic’s start and one dated after. We then analyzed the differences using data collected from medical records and from the Youth Self Report (YSR) tests performed.Results:Our study confirms a large increase in the number of cases of AN and restrictive EDs during the pandemic/post-pandemic period, the clinical characteristics of these cases instead seem substantially unchanged compared to the pre-pandemic ones.Conclusions:The pandemic has led to a large increase in the number of these EDs, underlining the need for attention to the topic and for new measures aimed at primary and secondary prevention
- …
