Students' Learning Strategies With Multiple Representations: Explanations of the Human Breathing Mechanism

The purpose of this study was to understand how students utilized multiple representations to learn and explain science concepts, in this case the human breathing mechanism. The study was conducted with Grade 11 students in a human biology class. Semistructured interviews and a two-tier diagnostic test were administered to evaluate students’ learning strategies of integrating multiple representations. The functions of multiple representations (complementary, constraining, and deeper understanding) suggested by Ainsworth (2008) were adapted as the analytical framework to better describe the participating students’ learning strategies with multiple representations (access complementary information, apply one representation to interpret the other, and evaluate representations). The categorization of students’ learning strategies facilitated interpreting their diverse understanding in relation to the multiple representations. In addition to a summary of students’ learning strategies, three case examples are presented to show how the framework was applied in the analysis and to discuss how the learning strategies interacted with students’

The wide spectrum high biocidal potency of Bioxy formulation when dissolved in water at different concentrations.

Traditional surface disinfectants that have long been applied in medicine, animal husbandry, manufacturing and institutions are inconvenient at best and dangerous at worst. Moreover, some of these substances have adverse environmental impacts: for example, quaternary ammonium compounds ("quats") are reproductive toxicants in both fish and mammals. Halogens are corrosive both to metals and living tissues, are highly reactive, can be readily neutralized by metals, and react with organic matter to form toxic, persistent by-products such as dioxins and furans. Aldehydes may be carcinogenic to both human and animals upon repeated exposures, are corrosive, cross-link living tissues and many synthetic materials, and may lose efficacy when pathogens enzymatically adapt to them. Alcohols are flammable and volatile and can be enzymatically degraded by certain bacterial pathogens. Quats are highly irritating to mucous membranes and over time can induce pathogen resistance, especially if they are not alternated with functionally different disinfectants. In contrast, peracetic acid (PAA), a potent oxidizer, liberates hydrogen peroxide (itself a disinfectant), biodegrades to carbon dioxide, water and oxygen, and is at least as efficacious as contact biocides e.g., halogens and aldehydes. Nevertheless, the standard form of liquid PAA is highly corrosive, is neutralized by metals and organic matter, gives off noxious odours and must be stored in vented containers. For the reasons stated above, Bioxy formulations were developed, a series of powder forms of PAA, which are odourless, stable in storage and safe to transport and handle. They generate up to 10% PAA in situ when dissolved in water. A 0.2% aqueous solution of Bioxy (equivalent to 200 ppm PAA) effected a 6.76 log reduction in Methicillin-resistant Staphylococcus aureus (MRSA) within 2 minutes after application. A 5% aqueous solution of Bioxy achieved a 3.93 log reduction in the bovine tuberculosis bacillus Mycobacterium bovis, within 10 minutes after contact. A 1% solution of Bioxy reduced vancomycin-resistant enterococci (VRE) and Pseudomonas aeruginosa by 6.31 and 7.18 logs, respectively, within 3 minutes after application. A 0.5% solution of Bioxy inactivated porcine epidemic diarrhea virus (PEDV) within 15 minutes of contact, and a 5% solution of Bioxy realized a 5.36 log reduction in the spores of Clostridium difficile within 10 minutes of application. In summary, Bioxy is safe and easy to transport and store, poses negligible human, animal and environmental health risks, shows high levels of pathogen control efficacy and does not induce microbial resistance. Further investigations are recommended to explore its use as an industrial biocide

Disinfection results against <i>Pseudomonas aeruginosa</i>.

<p>Disinfection results against <i>Pseudomonas aeruginosa</i>.</p

Control assay after 10 min exposure to 5% w/v Bioxy in neutralizer.

<p>Control assay after 10 min exposure to 5% w/v Bioxy in neutralizer.</p

Disinfection results against <i>Staphylococcus aureus</i>.

<p>Disinfection results against <i>Staphylococcus aureus</i>.</p

<i>P</i>. <i>aeruginosa</i> control assay after 3 min exposure to 1% w/v Bioxy in neutralizer.

<p><i>P</i>. <i>aeruginosa</i> control assay after 3 min exposure to 1% w/v Bioxy in neutralizer.</p

<i>M</i>. <i>bovis</i> neutralizer toxicity control assay after 5 min exposure to neutralizer in PSS.

<p><i>M</i>. <i>bovis</i> neutralizer toxicity control assay after 5 min exposure to neutralizer in PSS.</p

Peracetic acid generation <i>in situ</i> via the reaction between TAED and [hydrogen peroxide derived from] percarbonate [17].

<p>Peracetic acid generation <i>in situ</i> via the reaction between TAED and [hydrogen peroxide derived from] percarbonate [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172224#pone.0172224.ref017" target="_blank">17</a>].</p

Viable counts of Methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) after 2 min exposure to positively- and negatively charged 0.2% w/v Bioxy.

<p>Viable counts of Methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) after 2 min exposure to positively- and negatively charged 0.2% w/v Bioxy.</p