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Ceramic samples made with a mixture of 70% ball clay and 30% quartz sand were moulded and then fired at 900 °C in an electric kiln. Samples were then treated with different products and analyses and tests were performed to evaluate the physical changes induced by the application of these products and their effects on the quality of the ceramics. A petrographic study indicated that the ceramics were composed of quartz, small amounts of mullite and sanidine and traces of hematite. Mineral clays (i.e. kaolinite) disappeared during firing. Two consolidating products (Paraloid B72 and Tegovakon V) and one water repellent (Silo 111) were applied to samples by capillarity, and physical changes (colour, water flow, porosity and pore size distribution) were measured. Finally, we carried out salt crystallization tests in order to determine which product improved the quality of the ceramics. Treated samples registered a decrease in porosity and a general increase in pore size. The application of Silo 111 drastically reduced water absorption by immersion and by capillarity. This product was also responsible for a decrease in pore interconnection. Samples treated with Tegovakon V performed better in terms of their overall hydric behaviour. Silo 111 was the only product that did not modify the colour of samples when compared with untreated ones, and after accelerated aging tests, samples treated with this product hindered the absorption of saline solution into ceramic pores and prevented their decay. Paraloid B72 did not improve any of the properties of the ceramics. 相似文献
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Azza M. Mohamed Mohga S. Abdalla Maha Z. Rizk El-Sayed M. E. Mahdy Abdel-Razik H. Farrag Fatma S. El-Sharabasy Hanan F. Aly Mohamed R. Mohamed 《Indian journal of clinical biochemistry : IJCB》2014,29(4):418-429
Anabasis articulata (Forssk) Moq. (Chenopodiaceae) is an herb, grows in Egypt, and used in folk medicine to treat diabetes, fever, and kidney infections. The protective and therapeutic effects of the ethanol extract of A. articulata aerial parts were evaluated against dimethylnitrosamine (DMN)-induced liver fibrosis, compared with the standard drug, silymarin. Hepatic hydroxyproline content, serum transforming growth factor-β1 (TGF-β1), interleukin 10 (IL-10) and fructosamine were measured as liver fibrosis markers. Hepatic malondialdehyde (MDA), nitric oxide (NO), catalase (CAT), glutathione reductase (GR) and glutathione content (GSH) were measured as oxidant/antioxidant markers. Parallel histopathological investigations were also performed. Protective and therapeutic administration of A. articulata (100 mg/kg daily for 4 weeks), markedly prevented DMN-induced loss in body and liver weights. The extract significantly inhibited the elevation of hepatic hydroxyproline, NO and MDA (P < 0.05), as well as serum fructosamine, and TGF-β1 (P < 0.05) induced by DMN while it restored IL-10 to normal level in both protective and therapeutic groups. Furthermore, A. articulata prevented the depletion in CAT, GR, and GSH levels (P ≤ 0.05). In addition, oral administration of A. articulata extract and silymarin to both protective and therapeutic groups reduced the increase in liver function enzyme activities; alanine and aspartate amintransferases, gamma-glutamyl transferase in addition to alkaline phosphatase, and caused significant increase in serum albumin concentration as compared to DMN group. These data corresponded closely with those obtained for the drug silymarin. Histopathological studies confirmed the biochemical data and revealed remarkable improvement in liver architecture. Thus, it could be concluded that, A. articulata extract exhibited in vivo hepatoprotective and therapeutic effects against DMN-induced liver injury and may act as a useful agent in controlling the progression of hepatic fibrosis through reduction of oxidative stress and improving liver function. 相似文献
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Fatma Emel Kocak Ozben Ozden Isiklar Havva Kocak Ayfer Meral 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2015,25(1):57-63
Introduction
Measurements of blood ethanol concentrations must be accurate and reliable. The most important factors affecting blood ethanol stability are temperature and storage time. In this study, we aimed to compare ethanol stability in plasma samples at -20 °C for the different storage periods.Materials and methods
Blood samples were collected from intoxicated drivers (N = 80) and initial plasma ethanol concentrations were measured immediately. Plasma samples were then stored at -20 °C and re-assessed after 2, 3, 4, or 5 months of storage. Differences between the initial and stored ethanol concentrations in each group (N = 20) were analyzed using Wilcoxon matched-pairs test. The deviation from the initial concentration was calculated and compared with Clinical Laboratory Improvement Amendments (CLIA’88) Proficiency Testing Limits. Relationships between the initial concentrations and deviations from initial concentrations were analyzed by Spearman’s correlation analysis. For all statistical tests, differences with P values of less than 0.05 were considered statistically significant.Results
Statistically significant differences were observed between the initial and poststorage ethanol concentrations in the overall sample group (P < 0.001). However, for the individual storage duration groups, analytically significant decreases were observed only for samples stored for 5 months, deviations from the initial concentrations exceeded the allowable total error (TEa). Ethanol decreases in the other groups did not exceed the TEa.Conclusion
According to our results, plasma ethanol samples can be kept at -20 °C for up to 3-4 months until re-analysis. However, each laboratory should also establish its own work-flow rules and criterion for reliable ethanol measurement in forensic cases.Key words: preanalytical phase, ethanol, stability, storage temperature 相似文献66.
Alghamdi Jawaher Mostafa Fatma Abubshait Aisha 《Education and Information Technologies》2022,27(6):7851-7868
Education and Information Technologies - This study aims to explore kindergarten student teachers’ readiness to integrate technology into their future classrooms and factors affect their... 相似文献
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Erkan Işık Firuzan Yeğin Sıddıka Koyuncu Ayşe Eser Fatma Çömlekciler Kübra Yıldırım 《International Journal for Educational and Vocational Guidance》2018,18(3):297-314
A short 12-item version of the Career Adapt-Abilities Scale–Short Form (CAAS-SF) was validated across three different age groups in the Turkish context. Scale scores demonstrated adequate to high internal consistency and 4-week test–retest reliability, good fit with the original four-factor model, factorial invariance across gender and age groups, strong convergence with the 24-item version, negative associations with trait anxiety and work stress, and positive associations with career decision self-efficacy. It was concluded that the Turkish version of the CAAS-SF appears to be a valid and reliable measure for assessing career adaptability and using it in career education and counseling process. 相似文献
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Fatma Betül Kurnaz Esin Ergün Hale Ilgaz 《Education and Information Technologies》2018,23(4):1719-1736
This study aimed to develop a rubric to assess participation of students in online discussion environments. For this purpose, the study included 168 students who participated in a course offered online during the spring semester of the 2015–2016 academic year. Developed based on the literature, the rubric consists of two parts (Form and Content, and Number and Density) and seven criteria in total. “Form and Content” consists of congruity of the message in terms of subject, clarity of the message, original value of the message, interactional value of the message, and directing the subject; whereas, “Number and Density” consists of the number of messages and their density. Four different discussion subjects were presented to the students in an online discussion environment. The researchers analyzed the students’ messages individually. Exploratory Factor Analysis was performed in order to obtain evidence for construct validity. After conducting the factor analysis, results showed that the first dimension, which is “form and content” sub-factor, is unidimensional. The “number and density” sub-factor was included in the graded scoring key based on the literature and expert opinion. The findings show that the graded scoring key is reliable and valid. 相似文献
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Fatma Burcu Topu İlknur Reisoğlu Turkan Karakus Yılmaz Yuksel Göktaş 《Education and Information Technologies》2018,23(4):1621-1637
The purpose of this study was to examine the correlation of different variables with information retention in guided 3D virtual learning environments by employing three experimental designs. In each experiments, different participants were included in the same population and different variables were considered. Information retention test, flow, presence, engagement scales were used as data collection tools. Namely measures of flow, presence and engagement were examined to see their correlation with retention in experiment 1, 2 and 3. As a result, not the total score of flow but focused attention, enjoyment and skill dimensions has a weak but significant correlation with information retention, while the challenge has a moderate and significant negative correlation. In the second experiment, retention had a significant, low-level relationship with teaching presence and cognitive presence, but it did not have a similar relationship with social presence. In the third experiment, information retention significantly correlated with affective and cognitive engagement, but not with behavioral engagement. Although the three studies’ participants were from the same population, It was seen that the differences in the level of relationship between information retention and the variables studied in each study. Nevertheless, it was found that the levels of flow, presence and engagement of students are important for information retention in a guided 3D virtual learning environment. The study is thought to guide researchers to design 3D virtual learning environments for different purposes, considering these variables. 相似文献
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Fatma Gizem Karaoglan Yilmaz Hatice Durak 《Education and Information Technologies》2018,23(3):1277-1295
Math is a subject in which students are generally not very interested and are unsuccessful compared to other courses. It has been suggested that digital stories designed for educational purposes could be used to prevent students’ lack of interest and failure in this subject. However, designing stories that are fit for purpose is important if the use of digital stories is to be successful. The purpose of this study is to investigate pre-service teachers’ opinions about how they utilized the steps of Gagne’s model while designing digital stories for math lessons. The participants in the study were 49 pre-service teachers studying at a Math Department at a Turkish state university in the spring term of the 2014–2015 academic year. The Pre-service Teachers’ Opinion Form and a Personal Information Form, both developed by the researchers, were used as data collection tools in the study, in which the qualitative method was adopted. Content analysis was utilized to analyze the data collected through open-ended questions. When the findings were examined it was seen that pre-service teachers had designed digital stories in which they often chose to attract attention by creating interesting characters in the “gaining students’ attention” step of Gagne’s teaching model, that the main character stated the objectives/topic in the story precisely in the “informing students of the objectives” step, and that the characters created repeated the previous topic in the “stimulating recall of prior learning” step. In the current study, the integration of digital story design into lesson plans in accordance with Gagne’s model was carried out and pre-service teachers’ opinions about their experiences of this process were investigated. 相似文献