Cytocompatible cellulose nanofibers from invasive plant species Agave americana L. and Ricinus communis L.: a renewable green source of highly crystalline nanocellulose     

Evdokimova  Olga L.  Alves  Carla S.  Krsmanović Whiffen  Radenka M.  Ortega  Zaida  Tomás  Helena  Rodrigues  João 《Journal of Zhejiang University. Science. B》2021,22(6):450-461

In this study, the fibers of invasive species Agave americana L. and Ricinus communis L. were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers. Cellulose nanofibers were obtained by two methods, based on either alkaline or acid hydrolysis. The morphology, chemical composition, and crystallinity of the obtained materials were characterized by scanning electron microscopy(SEM) together with energy-dispersive X-ray spectroscopy(EDX), dynamic light scattering(DLS), X-ray diffraction(XRD), and Fourier transform infrared(FTIR)spectroscopy. The crystallinity indexes(CIs) of the cellulose nanofibers extracted from A. americana and R. communis were very high(94.1% and 92.7%, respectively). Biological studies evaluating the cytotoxic effects of the prepared cellulose nanofibers on human embryonic kidney 293 T(HEK293 T) cells were also performed. The nanofibers obtained using the two different extraction methods were all shown to be cytocompatible in the concentration range assayed(i.e., 0-500 μg/mL). Our results showed that the nanocellulose extracted from A. americana and R. communis fibers has high potential as a new renewable green source of highly crystalline cellulose-based cytocompatible nanomaterials for biomedical applications.  相似文献   

Algebraic and fractional thinking in collective mathematical reasoning     

Eriksson  Helena  Sumpter  Lovisa 《Educational Studies in Mathematics》2021,108(3):473-491

Educational Studies in Mathematics - This study examines the collective mathematical reasoning when students and teachers in grades 3, 4, and 5 explore fractions derived from length comparisons, in...  相似文献   

Problems and trends in Dutch education     

Helena W. F. Stellwag 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1957,3(1):54-68

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Questioning Styles and Students' Learning: Four case studies     

Helena Pedrosa de Jesus  Patr?′cia Almeida  Mike Watts 《教育心理学》2004,24(4):531-548

A study of the relationships between students' questioning and learning styles is being conducted on data collected in two university semesters with a sample of 300 students. This report discusses the results of case studies looking in depth at four of the students. These were involved in further data collection through written and oral questions, interviews and classroom observation experiments. The main aim is to unravel the interrogative bases of the students' learning by looking at the quality and quantity of questions they ask. This means that among other characteristics, the nature and the deliberative or spontaneous use of questions by the four students were investigated. It was possible to distinguish question‐askers by tallying their questions. Their learning styles were characterised using Kolb's Learning Styles Inventory. The study also allowed for snapshots of how particular learners shape questions. Looking at the way in which these questioning styles fit with their orientations to learning, and how this drives learning, informs what teaching might best then ensue.  相似文献   

Book reviews     

Stellwag  Helena W. F.  Völcker  Otto  de Bousingen  R. Durand  Roucek  Joseph R.  Langeveld  M. J.  Maack  Rudolf 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1958,4(1):485-490

International Review of Education -  相似文献   

Task-related variation in communication of mothers and their sons with learning disability     

Paula Lyytinen  Helena Rasku-Puttonen  Timo Ahonen  Anna-Maija Poikkeus  Marja-Leena Laakso 《European Journal of Psychology of Education - EJPE》1995,10(1):3-12

The purpose of the present study was to examine whether mother-child communication patterns vary as a function of the type of the task. Groups of learning disabled (LD=30) and normally achieving boys (NLD=30) were videotaped interacting with their mothers in two different tasks. The children were matched for age (8 to 11 year-olds) and for parent’s SES. The results indicated that the teaching task differentiated the groups more than did the story task. Academic character of the teaching task increased mothers’ task involvement in both groups. Mothers of the LD group showed, however, significantly more dominance and expressed less emotionality while teaching their child. Mothers’ interaction partly followed from their children’s behaviour on this task. The children with LD did not cooperate with their mothers and were not emotionally involved in the teaching task as highly as were the normally achieving children. Corresponding features of interaction were not found for the LD group in the story task. Consistency of children’s communication across the tasks was significant in the LD group. The normally achieving boys were more responsive to changes in task conditions showing different behavior as a function of task.  相似文献   

FísicActiva: applying active learning strategies to a large engineering lecture     

Adriana Auyuanet  Helena Modzelewski  Silvia Loureiro  Daniel Alessandrini  Marina Míguez 《European Journal of Engineering Education》2018,43(1):55-64

This paper presents and analyses the results obtained by applying Active Learning techniques in overcrowded Physics lectures at the University of the Republic, Uruguay. The course referred to is Physics 1, the first Physics course that all students of the Faculty of Engineering take in their first semester for all the Engineering-related careers. Qualitative and quantitative data corresponding to three semesters are shown and discussed, indicating that the students that attended these lectures outperformed the students that followed the course in the traditional way: the pass rates increased, whereas the failure rates decreased. The students highly valued this methodology, in particular, the interactive and relaxed dynamics, highlighting the concern of professors to answer questions by means of new questions so as to promote reasoning. The results obtained point to a work path that deserves to be deepened and extended to other Engineering courses.  相似文献   

Children with Special Education Needs and Subjective Well-being: Social and Personal Influence     

Tania Gaspar  Helena Bilimória  Francisca Albergaria  Margarida Gaspar Matos 《International Journal of Disability, Development & Education》2016,63(5):500-513

Children and adolescents with cognitive and developmental difficulties show difficulty in social interaction, feelings of rejection, autonomy, social rules and in behavioural and emotional self-regulation. Importantly, their subjective well-being is associated to social support and personal factors, such as self-esteem and a positive self-image. The data were collected in 16 schools, 8 in the North Region and 8 in the Lisbon Region of Portugal. The sample is composed by 1181 young people of which 51.5% were female, with ages ranging between 8 and 17 years. From the sample, 2.6% had special educational needs (SEN), and 3% did not use the Portuguese language at home. 12.2% had been retained one grade or more. Three regression models were built. Model 1 establishes the association between having SEN, grade and subjective well-being. The final model with all variables showed that social and personal characteristics present a stronger explicative value on children and adolescents’ subjective well-being. The model also showed that, when social and personal variables are included the association between being a student with SEN and well-being is not statistically significant. Research and intervention implications include the need to promote subjective well-being, social and personal skills and a positive development in children and adolescents with SEN.  相似文献   

Stop taking uncivil liberties with DNA     

Kennedy H 《New scientist (1971)》2004,181(2439):20-21

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The Emergence of a ‘New Orthodoxy’: public debates on women's capacities and education in Portugal, 1880‐1910     

Helena C. Araújo 《Gender and education》1992,4(1-2):7-24

The paper examines the emergence of the new definitions of women's position which constituted a ‘new orthodoxy’ at the turn of the nineteenth century in Portugal. ‘Women's nature’ and the ‘aims of women's education’ were the most debated issues. Different ideological positions were identified. The examination of these debates and of the emerging ‘new orthodoxy’ illustrates women's transition from ‘private’ forms of patriarchy to ‘public’ forms of patriarchy. It also demonstrates that this transition became an arena of contestation and negotiation, in the specific conditions of Portuguese society.  相似文献