Behavior of Ants Escaping from a Single-Exit Room

<div><p>To study the rules of ant behavior and group-formation phenomena, we examined the behaviors of <i>Camponotus japonicus</i>, a species of large ant, in a range of situations. For these experiments, ants were placed inside a rectangular chamber with a single exit that also contained a filter paper soaked in citronella oil, a powerful repellent. The ants formed several groups as they moved toward the exit to escape. We measured the time intervals between individual escapes in six versions of the experiment, each containing an exit of a different width, to quantify the movement of the groups. As the ants exited the chamber, the time intervals between individual escapes changed and the frequency distribution of the time intervals exhibited exponential decay. We also investigated the relationship between the number of ants in a group and the group flow rate.</p></div

<i>Q</i> (mean flow rate) of all of experimental repetitions for the six different exit widths.

<p>The six exit widths were 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm). The square represents the <i>Q</i> (mean flow rate) for each exit width. The data indicate no obvious linear relationship between <i>Q</i> (mean flow rate) and <i>d</i> (exit size).</p

Video recording of ants evacuating from a single-exit room.

<p>The exit width is 2<i>w</i> = 1.0 cm, and a 3.3% concentration of citronella was used.</p

Relationship between the number of ants in a group (<i>S</i>) and <i>Q</i>_<i>S</i> through an exit.

<p>(A), (B) and (C) show the relationship between <i>S</i> and <i>Q</i>_{<b><i>S</i></b>} for the 1<i>w</i> (when <i>N</i>≥2), 2<i>w</i>-6<i>w</i> (when <i>N</i>≥2) and 2<i>w</i>-6<i>w</i> (when <i>N</i>≥3) exit widths, respectively. (A), (B) and (C) reveal a trend toward an increase in <i>Q</i>_{<b><i>S</i></b>} with increasing <i>S</i> only when the exit width was 1<i>w</i> (0.5 cm).</p

Green and gentle synthesis of Cu₂O nanoparticles using lignin as reducing and capping reagent with antibacterial properties

<div><p>In this work, Cu₂O nanoparticles of a particular shape were prepared by an eco-friendly, gentle and low-cost synthetic method using lignin as a reducing and capping reagent. Structure and morphology of the Cu₂O nanoparticles were characterised by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction (XRD) and Fourier-transform (FT-IR) spectroscopy. The results established that Cu₂O nanoparticles coated by lignin showed a particular shape. The morphology of Cu₂O nanoparticles presented as some loose accumulation of particles just like broccoli, and the particle size range was between 100 and 200 nm. And, the XRD revealed the structure of crystalline of the Cu₂O nanoparticles. In addition, the sterilisation of Cu₂O nanoparticles on <i>Staphylococcus aureus</i> (<i>S. aureus</i>) and <i>Escherichia coli</i> (<i>E. coli</i>) was also investigated. The Cu₂O nanoparticles showed effective bactericidal activity against <i>E. coli</i> and <i>S. aureus</i>. The antibacterial rate could get 100% after 30 min with 4.0 g/L Cu₂O nanoparticles. Furthermore, the Cu₂O nanoparticles were confirmed to have low cytotoxicity.</p></div

Relationship between the value of <i>β</i> and the six different exit widths.

<p>The six exit widths were 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm). The square represents the value of <i>β</i> for each exit width, and the solid line represents the result of linear fitting. A trend in which the value of <i>β</i> decreased as the exit width increased is evident.</p

Analysis of the correlation between <i>Q</i>_<i>S</i> and <i>S</i> for the 1<i>w</i> exit width in the evacuation experiments.

<p>It is shown that <i>Q</i>_<i>S</i> and <i>S</i> are significantly correlative.</p><p>^a* Correlation is significant at the 0.05 level (2-tailed).</p><p>^b** Correlation is significant at the 0.01 level (2-tailed).</p><p>Analysis of the correlation between <i>Q</i>_<i>S</i> and <i>S</i> for the 1<i>w</i> exit width in the evacuation experiments.</p

Mean <i>Q</i>_<i>S</i> (<i>N</i>≥3) and <i>Q</i> for all experimental repetitions for the six different exit widths.

<p>The six exit widths were 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm). The square and circle represent the mean <i>Q</i>_{<b><i>S</i></b>} and <i>Q</i> for each exit width, respectively. Similar trends exist between mean <i>Q</i>_{<b><i>S</i></b>} and <i>d</i> and between <i>Q</i> and <i>d</i>.</p

Comparison of the number of escaped ants between treatment and control experiments using the t-test.

<p>One, two, and three stars indicate a <i>P</i>-value below 0.05, 0.01, and 0.001, respectively. (A), (B), (C), (D), (E), and (F) compare the results of the 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm) exit widths, respectively. Many more ants escaped during the treatment experiments than during the control experiments.</p

Comparison of time intervals among ant experiments with six exit widths using the t-test.

<p>One, two, and three stars indicate a <i>P</i>-value below 0.05, 0.01, and 0.001, respectively. (A), (B), (C), (D), (E), and (F) show the results of comparisons between the exit widths 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm), with each exit width being compared with every other exit width.</p