Spores of puffball fungus Lycoperdon pyriforme as a reference standard of stable monodisperse aerosol for calibration of optical instruments

Advanced air quality control requires real-time monitoring of particulate matter size and concentration, which can only be done using optical instruments. However, such techniques need regular calibration with reference samples. In this study, we suggest that puffball fungus (Lycoperdon pyriforme) spores can be utilized as a reference standard having a monodisperse size distribution. We compare the Lycoperdon pyriforme spores with the other commonly used reference samples, such as Al2O3 powder and polystyrene latex (PSL) microspheres. Here we demonstrate that the puffball spores do not coagulate and, thus, maintain the same particle size in the aerosol state for at least 15 minutes, which is enough for instrument calibration. Moreover, the puffball mushrooms can be stored for several years and no agglomeration of the spores occurs. They are also much cheaper than other calibration samples and no additional devices are needed for aerosol generation since the fungal fruiting body acts as an atomizer itself. The aforementioned features make the fungal spores a highly promising substance for calibration and validation of particle size analyzers, which outperforms the existing, artificially produced particles for aerosol sampling. Furthermore, the L. pyriforme spores are convenient for basic research and development of new optical measurement techniques, taking into account their uniform particle size and absent coagulation in the aeroso

Conditions for Waveblock Due to Anisotropy in a Model of Human Ventricular Tissue.

Waveblock formation is the main cause of reentry. We have performed a comprehensive numerical modeling study of block formation due to anisotropy in Ten Tusscher and Panfilov (2006) ionic model for human ventricular tissue. We have examined the border between different areas of myocardial fiber alignment and have shown that blockage can occur for a wave traveling from a transverse fiber area to a longitudinal one. Such blockage occurs for reasonable values of the anisotropy ratio (AR): from 2.4 to 6.2 with respect to propagation velocities. This critical AR decreases by the suppression of INa and ICa, slightly decreases by the suppression of IKr and IKs, and substantially increases by the suppression of IK1. Hyperkalemia affects the block formation in a complex, biphasic way. We provide examples of reentry formation due to the studied effects and have concluded that the suppression of IK1 should be the most effective way to prevent waveblock at the areas of abrupt change in anisotropy

Schematic representation of the computational setup in 2D.

<p>The tissue is divided into two parts with an orthogonal fiber orientation. The boundary is shown by the yellow dashed line. In the left part, the fibers (represented by thin lines) are parallel to the boundary, and in the right part, the fibers are orthogonal to the boundary. Two propagating waves are schematically shown as greyscale images. When stimulation was applied to the left border, wave propagation was observed to be translationally symmetric along the y axis and could be studied in 1D simulations.</p

Formation of transient reentry (ectopic beats) at the border between areas with orthogonal fiber orientation.

<p>Two stimuli were applied 6 mm from the border with a delay of 500 ms. The AR is 2.0 and [<i>K</i>⁺]<i>o</i> is 10 mM. Size of the tissue: 6.4 cm x 3.2 cm.</p

The dependencies of the critical period of stimulation on the AR for normal cardiomyocytes (red line) and with the inward rectifier potassium current <i>I</i>_<i>K</i>1 suppressed.

<p>The dependencies of the critical period of stimulation on the AR for normal cardiomyocytes (red line) and with the inward rectifier potassium current <i>I</i>_<i>K</i>1 suppressed.</p

The dependencies of the critical period of stimulation on the AR for normal cardiomyocytes (red line) and with various potassium currents suppressed.

<p>Inhibition of (a)—<i>I</i>_<i>Kr</i> and (b)—<i>I</i>_<i>Ks</i>. The vertical asymptotes to these plots correspond to the critical AR for a single travelling pulse.</p

Reentry formation at the border between areas with orthogonal fiber orientation, stabilized at the isotropic area.

<p>Two point stimuli were applied 6 mm from the border with a delay of 500 ms. The AR is 2.0 and [<i>K</i>⁺]<i>o</i> is 10 mM. Fiber alignment is shown in the left figure. Size of the tissue: 6.4 cm x 3.2 cm.</p

Drift of the reentry.

<p>The same simulation as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141832#pone.0141832.g008" target="_blank">Fig 8</a>. Size of the tissue: 25.6 cm x 3.2 cm.</p

The dependencies of the critical period of stimulation on the AR for normal cardiomyocytes (blue line), with the addition of various channel blockers.

<p>Inhibition of (a)—<i>I</i>_<i>Na</i>, (b)—<i>I</i>_<i>Ca</i>.</p

Conditions for waveblock formation in hyperkalemia.

<p>a) The dependence of the critical period of stimulation on the AR for various potassium concentrations outside of the cell [<i>K</i>⁺]_<i>o</i>. The blue line shows the critical period of stimulation under normal conditions ([<i>K</i>⁺]_<i>o</i> = 5.4 mM). b) The dependence of the critical AR on potassium concentration outside of the cell [<i>K</i>⁺]_<i>o</i> for various stimulation frequencies.</p