| 1. |
- Shroff, Sailee, et al.
(författare)
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Tree Species-Dependent Inactivation of Coronaviruses and Enteroviruses on Solid Wood Surfaces
- 2024
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 16:23, s. 29621-29633
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Tidskriftsartikel (refereegranskat)abstract
- The ongoing challenge of viral transmission, exemplified by the Covid pandemic and recurrent viral outbreaks, necessitates the exploration of sustainable antiviral solutions. This study investigates the underexplored antiviral potential of wooden surfaces. We evaluated the antiviral efficacy of various wood types, including coniferous and deciduous trees, against enveloped coronaviruses and nonenveloped enteroviruses like coxsackie virus A9. Our findings revealed excellent antiviral activity manifesting already within 10 to 15 min in Scots pine and Norway spruce, particularly against enveloped viruses. In contrast, other hardwoods displayed varied efficacy, with oak showing effectiveness against the enterovirus. This antiviral activity was consistently observed across a spectrum of humidity levels (20 to 90 RH%), while the antiviral efficacy manifested itself more rapidly at 37 degrees C vs 21 degrees C. Key to our findings is the chemical composition of these woods. Resin acids and terpenes were prevalent in pine and spruce, correlating with their antiviral performance, while oak's high phenolic content mirrored its efficacy against enterovirus. The pine surface absorbed a higher fraction of the coronavirus in contrast to oak, whereas enteroviruses were not absorbed on those surfaces. Thermal treatment of wood or mixing wood with plastic, such as in wood-plastic composites, strongly compromised the antiviral functionality of wood materials. This study highlights the role of bioactive chemicals in the antiviral action of wood and opens new avenues for employing wood surfaces as a natural and sustainable barrier against viral transmissions.
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| 2. |
- Tossavainen, Timo, et al.
(författare)
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On mathematics students' understanding of the equation concept
- 2011
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Ingår i: Far East Journal of Mathematical Education. - Allahabad : Pushpa Publishing House. - 0973-5631. ; 6:2, s. 127-147
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Tidskriftsartikel (refereegranskat)abstract
- We analyze data on mathematics students’ understanding of the concept of equation. A majority of the participants (N = 128) studies in teacher education programs in Finland, Sweden and South Africa. The data reveals a variety of fundamentally different concept definitions of equation, of which only a half can be seen to be correct. In the students’ concept image of equation, it is commonly assumed that every equation must possess the truth value ‘true’ in spite of the fact that any considerations related to the truth value only rarely appear in their concept definitions. Also the presence of a variable is regularly assumed in the participants’ concept images. Both a chain of equations and a pair of equivalent equations are surprisingly often seen being a single equation. Finally, the incomplete understanding of the reflexive and symmetric properties of equality often hindersstudents from identifying equations. The study is based on both phenomenographic andquantitative analyses of the students’ answers to a questionnaire. .
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| 3. |
- Tossavainen, Timo, 1971-, et al.
(författare)
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Some South African mathematics teachers' concept images of the equation concept
- 2012
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Ingår i: African Journal of Research in Mathematics, Science and Technology Education. - : Electronic Publishing. - 1811-7295. ; 16:3, s. 376-389
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we examine the concept definitions a group of South African upper secondary school mathematics teachers (N = 47) express and how their understanding of the truth value, the role of variable and the syntax of expression appear in the participants' explanations for their assessment of examples and non-examples of equations. We use content analysis and standard quantitative methods. The data consists of the participants' answers to a questionnaire reflecting both teachers' concept definitions of equation and their skills in classifying examples and non-examples of equation. Altogether 27 participants were able to give a correct definition of the equation concept. Ten participants' definition was slightly ambiguous yet meaningful and ten participants failed in this task. In general, the participants had very high confidence in the sufficiency of their skills in classifying examples and non-examples of equations. Nevertheless, on average, they only succeeded in correctly identifying an equation in 13 of 24 items, with most of the equations being quite simple and none beyond the upper secondary school level. The findings of this study also reveal a common and dominant conception that equations should always possess the truth value 'true' although truth value is discussed only in one participant's concept definition. Secondly, the participants are quite careless about the syntax and the involved binary relation in particular despite the fact that the correct form of equations and the equality relation were regularly mentioned in their concept definitions of equation. Finally, some participants seem to think that there is only one equation related to each algebraic problem.
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