Name: experimental methods of dust charging and mobilization on surfaces with exposure to ultraviolet radiation or plasmas
Uploaded: 2018-04-03T13:30:00
Description: Watch this Scientific Journal Video about Experimental Methods of Dust Charging and Mobilization on Surfaces with Exposure to Ultraviolet Radiation or Plasmas at JoVE.com

This work was supported by the NASA/SSERVI&#39;s Institute for Modeling Plasma, Atmospheres and Cosmic Dust (IMPACT) and by the NASA Solar Systems Workings Program (Grant number: NNX16AO81G).

1. Vacuum chamber setup
<ol>
	<li>Place an insulating rubber sheet (0.2 cm thick, 5 cm in diameter) with a central hole 1.9 cm in diameter on an insulating plate (2 cm thick and 20 cm in diameter) (Figure 2a, b). Load insulating, irregularly-shaped dust particles (between 10 and 50 &#956;m in diameter) in the hole.</li>
	<li>Place the insulating plate on a metal plate standing in the middle of a vacuum chamber. Electrically isolate the metal plate from the chamber using ce...

<ol>
	<li>Criswell, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Horizon-glow+and+the+motion+of+lunar+dust.">Horizon-glow and the motion of lunar dust.</a> Photon and Particle Interactions with Surfaces in Space. , 545-556 (1973).</li><li>Rennilson, J. J., Criswell, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surveyor+observations+of+lunar+horizon-glow.">Surveyor observations of lunar horizon-glow.</a> Moon. 10 (2), 121-142 (1974).</li><li>Colwell, J. E., Batiste, S., Hor&#225;nyi, M., Robertson, S., Sture, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lunar+surface:+Dust+dynamics+and+regolith+mechanics.">Lunar surface: Dust dynamics and regolith mechanics.</a> Rev. 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Geophys. Res. 97 (A3), 2935-2942 (1992).</li><li>Flanagan, T. M., Goree, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dust+release+from+surfaces+exposed+to+plasma.">Dust release from surfaces exposed to plasma.</a> Phys. Plasmas. 13 (12), 123504 (2006).</li><li>Sickafoose, A. A., Colwell, J. E., Hor&#225;nyi, M., Robertson, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+levitation+of+dust+grains+in+a+plasma+sheath.">Experimental levitation of dust grains in a plasma sheath.</a> J. Geophys. Res. 107 (A11), 1408 (2002).</li><li>Wang, X., Hor&#225;nyi, M., Robertson, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experiments+on+dust+transport+in+plasma+to+investigate+the+origin+of+the+lunar+horizon+glow.">Experiments on dust transport in plasma to investigate the origin of the lunar horizon glow.</a> J. Geophys. Res. 114, A05103 (2009).</li><li>Wang, X., Hor&#225;nyi, M., Robertson, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigation+of+dust+transport+on+the+lunar+surface+in+a+laboratory+plasma+with+an+electron+beam.">Investigation of dust transport on the lunar surface in a laboratory plasma with an electron beam.</a> J. Geophys. Res. 115, A11102 (2010).</li><li>Wang, X., Hor&#225;nyi, M., Robertson, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dust+transport+near+electron+beam+impact+and+shadow+boundaries.">Dust transport near electron beam impact and shadow boundaries.</a> Planet. Space Sci. 59 (14), 1791-1794 (2011).</li><li>Hartzell, C. M., Wang, X., Scheeres, D. J., Hor&#225;nyi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+demonstration+of+the+role+of+cohesion+in+electrostatic+dust+lofting.">Experimental demonstration of the role of cohesion in electrostatic dust lofting.</a> Geophys. Res. Lett. 40 (6), 1038-1042 (2013).</li><li>Wang, X., Hor&#225;nyi, M., Sternovsky, Z., Robertson, S., Morfill, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+laboratory+model+of+the+lunar+surface+potential+near+boundaries+between+sunlit+and+shadowed+regions.">A laboratory model of the lunar surface potential near boundaries between sunlit and shadowed regions.</a> Geophys. Res. Lett. 34 (16), L16104 (2007).</li><li>Ding, N., Wang, J., Polansky, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+dust+charging+on+a+lunar+regolith+simulant+surface.">Measurement of dust charging on a lunar regolith simulant surface.</a> IEEE Trans. Plasma Sci. 41 (12), 3498-3504 (2013).</li><li>Sheridan, T. E., Hayes, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Charge+fluctuations+for+particles+on+a+surface+exposed+to+plasma.">Charge fluctuations for particles on a surface exposed to plasma.</a> Appl. Phys. Lett. 98 (9), 091501 (2011).</li><li>Heijmans, L. C. J., Nijdam, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dust+on+a+surface+in+a+plasma:+A+charge+simulation.">Dust on a surface in a plasma: A charge simulation.</a> Phys. Plasmas. 23 (6), 043703 (2016).</li><li>Wang, X., Schwan, J., Hsu, H. -. W., Gr&#252;n, E., Hor&#225;nyi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dust+charging+and+transport+on+airless+planetary+bodies.">Dust charging and transport on airless planetary bodies.</a> Geophys. Res. Lett. 43 (12), 6103-6110 (2016).</li><li>Schwan, J., Wang, X., Hsu, H. -. W., Gr&#252;n, E., Hor&#225;nyi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+charge+state+of+electrostatically+transported+dust+on+regolith+surfaces.">The charge state of electrostatically transported dust on regolith surfaces.</a> Geophys. Res. Lett. 44 (7), 3059-3065 (2017).</li><li>Allen, C. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Martian+Regolith+Simulant+JSC-Mars-1.">Martian Regolith Simulant JSC-Mars-1.</a> The 29th Lunar and Planetary Science Conference. , (1998).</li><li>Martin, N. L. S., von Engel, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+reflection+of+slow+electrons+from+a+soot-covered+surface.">The reflection of slow electrons from a soot-covered surface.</a> J. Phys DAppl Phys. 10 (6), 863-868 (1977).</li><li>Halekas, J. S., Delory, G. T., Lin, R. P., Stubbs, T. J., Farrell, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lunar+Prospector+measurements+of+secondary+electron+emission+from+lunar+regolith.">Lunar Prospector measurements of secondary electron emission from lunar regolith.</a> Planet. Space Sci. 57 (1), 78-82 (2009).</li><li>Wiese, R., Sushkov, V., Kersten, H., Ikkurthi, V. R., Schneider, R., Hippler, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavior+of+a+porous+particle+in+a+radiofrequency+plasma+under+pulsed+argon+ion+beam+bombardment.">Behavior of a porous particle in a radiofrequency plasma under pulsed argon ion beam bombardment.</a> New J. Phys. 12, 033036 (2010).</li><li>Richterov&#225;, I., N&#277;me&#269;ek, Z., Ber&#225;nek, M., &#352;afr&#225;nkov&#225;, J., Pavl&#367;, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Secondary+emission+from+non-spherical+dust+grains+with+rough+surfaces:+Applications+to+lunar+dust.">Secondary emission from non-spherical dust grains with rough surfaces: Applications to lunar dust.</a> Astrophys. J. 761 (2), 108 (2012).</li><li>Ma, Q., Matthews, L. S., Land, V., Hyde, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Charging+of+aggregate+grains+in+astrophysical+environments.">Charging of aggregate grains in astrophysical environments.</a> Astrophys. J. 763 (2), 77 (2013).</li><li>Dove, A., Hor&#225;nyi, M., Wang, X., Piquette, M., Poppe, A. R., Robertson, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+study+of+a+photoelectron+sheath.">Experimental study of a photoelectron sheath.</a> Phys. Plasmas. 19 (4), 043502 (2012).</li><li>Zimmerman, M. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Grain-scale+supercharging+and+breakdown+on+airless+regoliths.">Grain-scale supercharging and breakdown on airless regoliths.</a> J. Geophys. 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For decades, the problem of electrostatic dust transport on the regolith of airless bodies remained an open question how regolith dust particles gain sufficiently large charges to become mobilized or lofted. Recent laboratory studies26,27 have fundamentally advanced the understanding of this problem.
Here, it is demonstrated three recently developed experiments to show dust charging and mobilization in thermal plasma with beam electron...

Airless planetary bodies, such as the Moon and asteroids, are covered with fine dust particles called regolith. These airless bodies, unlike Earth, are directly exposed to solar wind plasma and solar ultraviolet (UV) radiation, causing the regolith dust to be charged. These charged dust particles may therefore be mobilized, lofted, transported, or even ejected and lost from the surface due to electrostatic forces. The first suggested evidence of this electrostatic process was the so-called &#34;lunar horizon glow&#34;, a distinct glow above the western horizon observed shortly after sunset by Surveyor 5, 6, and 7 spacecraft five decades ago (Figure 1a)1,2,3. It has been hypothesized that this glow was caused by sunlight scattered off from electrostatically lofted dust particles (5 &#956;m radius) to a height &#60; 1 m above the surface near the lunar terminator1,2,3. Electrostatically released fine dust was also suggested to be responsible for the ray-like streamers reaching a high altitude reported by the Apollo astronauts4,5.
Ever since these Apollo observations, a number of observations over other airless bodies were also linked to the mechanisms of electrostatic dust mobilization or lofting, such as the radial spokes in the Saturn&#39;s rings6,7,8, the dust ponds on asteroid Eros (Figure 1b)9 and comet 67P10, the porous surfaces indicated from the main-belt asteroid spectra11, the unusually smooth surface of Saturn&#39;s icy moon Atlas12, and the regolith at the lunar swirls13. In addition, the degradation of the laser retroreflectors on the lunar surface may be also caused by the accumulation of electrostatically lofted dust14.
Laboratory studies have been largely motivated by these unusual space observations in order to understand the physical processes of dust charging and transport. Dust mobilization has been observed in various plasma conditions, in which dust particles are shed off from a glass sphere surface15,16, levitated in plasma sheaths17, and recorded to move on both conducting and insulating surfaces18,19,20,21. However, how dust particles gain large enough charges to be lofted or mobilized remained poorly understood. The measurements of the charges on individual dust particles on a smooth surface22 and the average charge density on a dusty surface23 immersed in plasmas show that the charges are far too small for dust particles to be lofted or mobilized.
In the prior theories16,24,25, the charging was only considered to occur on the top surface layer that is directly exposed to UV or plasma. Charges are often considered to be distributed uniformly over the entire dusty surface, i.e., each individual dust particle acquires the same amount of charge, described by the so-called &#34;shared charge model&#34;16. However, the charges calculated from this model are much smaller than the gravitational force alone. A charge fluctuation theory that accounts for the stochastic process of the fluxes of electrons and ions to the surface16,24 shows a temporal enhancement in the electrostatic force, but it remains small in comparison to the gravitational force.
In this paper, electrostatic dust lofting and mobilization is demonstrated using three recently developed experiments26, which are important for understanding dust transport on the regolith of airless planetary bodies. These experiments are performed in the conditions of thermal plasma with beam electrons, beam electrons only or UV radiation only. These experiments demonstrate the validity of the recently developed &#34;patched charge model&#34;26,27, in which microcavities formed between neighboring dust particles below the surface can re-absorb the emitted photo and/or secondary electrons, generating large negative charges on the surfaces of the neighboring dust particles. The repulsive forces between these negative charges can become large enough to mobilize or lift off the dust particles.

<table>
	<tbody>
		<tr>
			<td>Vacuum chamber</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Vacuum electrode feedthrough</td>
			<td>Lesker</td>
			<td>EFT0113053</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten filament (0.1 mm thick)</td>
			<td>Goodfellow</td>
			<td>W055250</td>
			<td>Thoriated</td>
		</tr>
		<tr>
			<td>Power supply #1 (0-8V, 3A)</td>
			<td>Agilent</td>
			<td>E3610A</td>
			<td>Or equivalent</td>
		</tr>
		<tr>
			<td>Power supply #2 (0-140V, 0.5A)</td>
			<td>Agilent</td>
			<td>E3612A</td>
			<td>Or equivalent</td>
		</tr>
		<tr>
			<td>UV lamp</td>
			<td>Osram</td>
			<td>XERADEX L40/120/SB-SX48/KF50HV</td>
			<td>Or equivalent</td>
		</tr>
		<tr>
			<td>Dust sample</td>
			<td>Any</td>
			<td>Mars or Lunar simulants or other types</td>
			<td>Irregularly-shaped, sieved, insulating</td>
		</tr>
		<tr>
			<td>Insulating plate</td>
			<td>Any</td>
			<td>NA</td>
			<td>Thickness &#62; 1 cm</td>
		</tr>
		<tr>
			<td>Rubber sheet</td>
			<td>Any</td>
			<td>NA</td>
			<td>Thickness &#62; 1 mm</td>
		</tr>
		<tr>
			<td>Metal plate</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Ceramic stands</td>
			<td>McMaster</td>
			<td>94335A130</td>
			<td>1/2&#34; diameter</td>
		</tr>
		<tr>
			<td>Video camera (consumer)</td>
			<td>Panasonic</td>
			<td>HC-VX870</td>
			<td>Or equivalent</td>
		</tr>
		<tr>
			<td>Video camera (high-speed)</td>
			<td>Phantom</td>
			<td>V2512</td>
			<td>&#62; 1000 fps</td>
		</tr>
		<tr>
			<td>LED lamp</td>
			<td>Any</td>
			<td>NA</td>
			<td>&#62; 500W Tungsten Equivalent</td>
		</tr>
	</tbody>
</table>

experimental methods of dust charging and mobilization on surfaces with exposure to ultraviolet radiation or plasmas

Electrostatic dust transport has been hypothesized to explain a number of observations of unusual planetary phenomena. Here, it is demonstrated using three recently developed experiments in which dust particles are exposed to thermal plasma with beam electrons, beam electrons only, or ultraviolet (UV) radiation only. The UV light source has a narrow bandwidth in wavelength centered at 172 nm. The beam electrons with the energy of 120 eV are created with a negatively biased hot filament. When the vacuum chamber is filled with the argon gas, a thermal plasma is created in addition to the electron beam. Insulating dust particles of a few tens of microns in diameter are used in the experiments. Dust particles are recorded to be lofted to a height up to a few centimeters with a launch speed up to 1 m/s. These experiments demonstrate that photo and/or secondary electron emission from a dusty surface changes the charging mechanism of dust particles. According to the recently developed &#34;patched charge model&#34;, the emitted electrons can be re-absorbed inside microcavities between neighboring dust particles below the surface, causing the accumulation of enhanced negative charges on the surrounding dust particles. The repulsive forces between these negatively charged particles may be large enough to mobilize and lift them off the surface. These experiments present the advanced understanding of dust charging and transport on dusty surfaces, and laid a foundation for future investigations of its role in the surface evolution of airless planetary bodies.

A set of experiments were performed using the top or bottom filaments. With the top filament setup, the hopping of the dust particles was recorded (Figure 3a). In contrast, the dust particles remained at rest when using the bottom filament. It has been measured that the vertical electric field at the surface was approximately same (16 V/cm) in both experiments under the conditions described in Protocol step 226. These results indicate ...

Watch this Scientific Journal Video about Experimental Methods of Dust Charging and Mobilization on Surfaces with Exposure to Ultraviolet Radiation or Plasmas at JoVE.com

Experimental Methods of Dust Charging and Mobilization on Surfaces with Exposure to Ultraviolet Radiation or Plasmas

Dust charging and mobilization is demonstrated in three experiments with exposure to thermal plasma with beam electrons, beam electrons only, or ultraviolet (UV) radiation only. These experiments present the advanced understanding of electrostatic dust transport and its role in shaping the surfaces of airless planetary bodies.

Electrostatic dust transport has been hypothesized to explain a number of observations of unusual planetary phenomena. Here, it is demonstrated using ...

The overall goal of this experiment is to show the mechanisms that cause regolith dust particles in space or laboratory conditions to gain enough charge to become lofted or mobilized. This method can help answer a key question about the role of electricity dust transport in shaping the surface of airless bodies in the solar system. This method paves the way for future studies including both experiment and computer modeling to ultimately explain the existing space observations and provide guidance for future mission investigations.This method demonstrate how to move dust particles in a controlled manner which can help other researchers to develop their own experiments. Demonstrating the procedure will be Noah Hood, an undergrad student from our laboratory. The experiments require a vacuum chamber.This one is 50 centimeters in diameter and 28 centimeters tall and connected to an argon tank and a pump system. Inside is a metal plate that is electrically isolated. At this point, prepare to load dust particles.Use an insulating plate 20 centimeters in diameter and two centimeters thick, and place on top of it an insulting rubber sheet with a central hole. Next, load insulating irregularly-shaped dust particles in the hole. Move the insulating plate to the vacuum chamber.There, place it on the metal plate inside. Next, set up a video camera to record dust movement. For illumination, use an LED light equivalent to at least a 500-watt incandescent source.This image is of the dust particles before any beams have interacted with them. This electron beam experiment requires two filaments. As with this example, install a thoriated tungsten filament on each of the two electrode feed-throughs.Install one of the feed-throughs on the top of the vacuum chamber. Connect this filament to filament power supplies. Then, install the second feed-through with a filament on the bottom of the chamber.Continue by pumping the chamber to the desired base pressure. Next, use the argon gas feed to fill the chamber to about one half millitorr. When ready, turn on the filament power supplies and set the bias voltage to negative 120 volts.Turn on the camera to record. At the power supply, increase the heating voltage. Stop when the emission current is a few milliamps.Record the response of the dust particles. Expose two energetic and thermal electrons that begin to move. Turn off the filament power supplies and connect them to the bottom filament.With the power supplies on, set the bias voltage to negative 40 volts. Increase the heating voltage to reach an emission current above 200 milliamps. Record the motion of the dust particles.Exposed to only thermal electrons, they do not move. Begin with the vacuum chamber with the bottom sealed. Have the dust particles loaded onto the insulating plate supported by the metal plate.Use only one feed-through. Install one thoriated tungsten filament onto it. Install the feed-through on the top of the chamber and connect the filament power supplies.In the first sequence, set the bias voltage to negative 120 volts. Then, increase the heating voltage. Stop when the emission current is a few milliamps.Record the response of the dust particles in the chamber. In this case, they move. The second sequence uses the same setup as the first.In the second sequence, set the bias voltage to zero. Increase the heating voltage to reach a heating current of about two amps. Then, gradually change the bias voltage from zero to negative 120 volts.Record the response of the dust particles in the chamber. In this case, they do not move. For this experiment, remove the electrode feed-through from the chamber.Install a 172-nanometer UV lamp on the feed-through. Reinstall the feed-through and connect the lamp's power supply. With the chamber at base pressure, turn on the lamp to irradiate the dust particles.Record the response of the particles under these conditions. In this experiment, 10 to 50-micrometer-diameter dust particles are exposed to plasma, and 120-electron-volt beam electrons. No particles are lofted when the electron beam is absent.This is consistent with secondary electrons contributing to dust charging. The lofted particles are induced by an electron beam created by first setting a bias voltage and then increasing the heating voltage, a process that creates secondary electrons. In contrast, no dust movement is seen when the heating voltage is first set followed by increasing the bias voltage, a process with no secondary electrons.Dust particles exposed to 172-nanometer UV lamp show dust hopping as indicated in this photo. When the dust is exposed to UV radiation for an extended time, the dust surface changes. This is captured in a series of photos in which the surface becomes smoother and eventually flattens out.After watching this video, you should have a good understanding of how to move dust particles in a controlled manner. The key point is to create full electrons and/or secondary electrons from dusty surfaces. Based on this methods, new experiments, as well as computer modeling, can be developed to better categorize the nature of dust charging and transport.This technique paves the way for researchers in space and planetary science, as well dusty plasmas, to explore the role of electrostatic dust transport in surface processing on airless planetary bodies and a near-surface dust environment around these bodies as well. Don't forget to wear gloves when handling thoriated tungsten wires because of thorium's low radioactivity. Also, cover the windows of the vacuum chamber to avoid any possible UV exposure.

experimental-methods-dust-charging-mobilization-on-surfaces-with

Research

JoVE Journal

Environment

Methods for Facilitating Microbial Growth on Pulp Mill Waste Streams and Characterization of the Biodegradation Potential of Cultured Microbes

The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high quality paper. Black liquor is a pulping waste generated by the kraft process that has potential for downstream bioconversion. However, the recalcitrant nature of the lignocellulose resources, its chemical derivatives that constitute the majority of available organic carbon within black liquor, and its basic pH present challenges to microbial biodegradation of this waste material. Methods for the collection and modification of black liquor for microbial growth are aimed at utilization of this pulp waste to convert the lignin, organic acids, and polysaccharide degradation byproducts into valuable chemicals. The lignocellulose extraction techniques presented provide a reproducible method for preparation of lignocellulose growth substrates for understanding metabolic capacities of cultured microorganisms. Use of gas chromatography-mass spectrometry enables the identification and quantification of the fermentation products resulting from the growth of microorganisms on pulping waste. These methods when used together can facilitate the determination of the metabolic activity of microorganisms with potential to produce fermentation products that would provide greater value to the pulping system and reduce effluent waste, thereby increasing potential paper milling profits and offering additional uses for black liquor.

Industrial wastes can be collected and modified to analyze microbial growth. Lignocellulose extraction techniques provide components to analyze specific biodegradation ability. Gas chromatography-mass spectrometry identifies fermentation products of microorganisms grown on pulping waste. These methods determine the metabolic capacity of microorganisms to degrade pulping waste.

The kraft process is applied to wood chips for separation of lignin from the polysaccharides within lignocellulose for pulp that will produce a high ...

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. I. Collection of Virus Samples

EPA Method 1615 was developed with a goal of providing a standard method for measuring enteroviruses and noroviruses in environmental and drinking waters. The standardized sampling component of the method concentrates viruses that may be present in water by passage of a minimum specified volume of water through an electropositive cartridge filter. The minimum specified volumes for surface and finished/ground water are 300 L and 1,500 L, respectively. A major method limitation is the tendency for the filters to clog before meeting the sample volume requirement. Studies using two different, but equivalent, cartridge filter options showed that filter clogging was a problem with 10% of the samples with one of the filter types compared to 6% with the other filter type. Clogging tends to increase with turbidity, but cannot be predicted based on turbidity measurements only. From a cost standpoint one of the filter options is preferable over the other, but the water quality and experience with the water system to be sampled should be taken into consideration in making filter selections.

EPA Method 1615 uses an electropositive filter to concentrate enteroviruses and noroviruses in environmental and drinking waters. This manuscript describes the procedure for collecting samples for Method 1615 analyses.

EPA Method 1615 was developed with a goal of providing a standard method for measuring enteroviruses and noroviruses in environmental and drinking waters. ...

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. II. Total Culturable Virus Assay

A standardized method is required when national studies on virus occurrence in environmental and drinking waters utilize multiple analytical laboratories. The U.S Environmental Protection Agency&#8217;s (USEPA) Method 1615 was developed with the goal of providing such a standard for measuring Enterovirus and Norovirus in these waters. Virus is concentrated from water using an electropositive filter, eluted from the filter surface with beef extract, and then concentrated further using organic flocculation. Herein we present the protocol from Method 1615 for filter elution, secondary concentration, and measurement of total culturable viruses. A portion of the concentrated eluate from each sample is inoculated onto ten replicate flasks of Buffalo Green Monkey kidney cells. The number of flasks demonstrating cytopathic effects is used to quantify the most probable number (MPN) of infectious units per liter. The method uses a number of quality controls to increase data quality and to reduce interlaboratory and intralaboratory variation. Laboratories must meet defined performance standards. Method 1615 was evaluated by examining virus recovery from reagent-grade and ground waters seeded with Sabin poliovirus type 3. Mean poliovirus recoveries with the total culturable assay were 111% in reagent grade water and 58% in groundwaters.

Here we present a procedure to measure total culturable viruses using the Buffalo Green Monkey kidney cell line. The procedure provides a standardized tool for measuring the occurrence of infectious viruses in environmental and drinking waters.

A standardized method is required when national studies on virus occurrence in environmental and drinking waters utilize multiple analytical laboratories. ...

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. Part III. Virus Detection by RT-qPCR

EPA Method 1615 measures enteroviruses and noroviruses present in environmental and drinking waters. This method was developed with the goal of having a standardized method for use in multiple analytical laboratories during monitoring period 3 of the Unregulated Contaminant Monitoring Rule. Herein we present the protocol for extraction of viral ribonucleic acid (RNA) from water sample concentrates and for quantitatively measuring enterovirus and norovirus concentrations using reverse transcription-quantitative PCR (RT-qPCR). Virus concentrations for the molecular assay are calculated in terms of genomic copies of viral RNA per liter based upon a standard curve. The method uses a number of quality controls to increase data quality and to reduce interlaboratory and intralaboratory variation. The method has been evaluated by examining virus recovery from ground and reagent grade waters seeded with poliovirus type 3 and murine norovirus as a surrogate for human noroviruses. Mean poliovirus recoveries were 20% in groundwaters and 44% in reagent grade water. Mean murine norovirus recoveries with the RT-qPCR assay were 30% in groundwaters and 4% in reagent grade water.

Here we present a procedure to quantify enterovirus and norovirus in environmental and drinking waters using reverse transcription-quantitative PCR. Mean virus recovery from groundwater with this standardized procedure from EPA Method 1615 was 20% for poliovirus and 30% for murine norovirus.

EPA Method 1615 measures enteroviruses and noroviruses present in environmental and drinking waters. This method was developed with the goal of having a ...

Exploring the Effects of Atmospheric Forcings on Evaporation: Experimental Integration of the Atmospheric Boundary Layer and Shallow Subsurface

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study evaporation under various surface boundary conditions to improve our current understanding and characterization of this multiphase phenomenon as well as to validate numerical heat and mass transfer theories that couple Navier-Stokes flow in the atmosphere and Darcian flow in the porous media. Experimental data were collected using a unique soil tank apparatus interfaced with a small climate controlled wind tunnel. The experimental apparatus was instrumented with a suite of state of the art sensor technologies for the continuous and autonomous collection of soil moisture, soil thermal properties, soil and air temperature, relative humidity, and wind speed. This experimental apparatus can be used to generate data under well controlled boundary conditions, allowing for better control and gathering of accurate data at scales of interest not feasible in the field. Induced airflow at several distinct wind speeds over the soil surface resulted in unique behavior of heat and mass transfer during the different evaporative stages.

A protocol for the design and construction of a soil tank interfaced to a small climate controlled wind tunnel to study the effects of atmospheric forcings on evaporation is presented. Both the soil tank and wind tunnel are instrumented with sensor technologies for the continuous in situ measurement of environmental conditions.

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study ...

A Flow-through Exposure System for Evaluating Suspended Sediments Effects on Aquatic Life

This paper describes the Fish Larvae and Egg Exposure System (FLEES). The flow-through exposure system is used to investigate the effects of suspended sediment on various aquatic species and life stages in the laboratory by using pumps and automating delivery of sediment and water to simulate suspension of sediment. FLEES data are used to develop exposure-response curves between the effects on aquatic organisms and suspended sediment concentrations at the desired exposure duration. The effects data are used to evaluate management practices used to reduce the interactions between aquatic organisms and anthropogenic causes of suspended sediments. The FLEES is capable of generating total suspended solids (TSS) concentrations as low as 30 to as high as 800 mg/L, making this system an ideal choice for evaluating the effects of TSS resulting from many activities including simulating low ambient levels of TSS to evaluating sources of suspended sediments from dredging operations, vessel traffic, freshets, and storms.

A robust and flexible flow-through exposure system designed to maintain sediment in suspension is presented. The system is used to investigate the effects of suspended sediment on various aquatic species and life stages in the laboratory.

This paper describes the Fish Larvae and Egg Exposure System (FLEES). The flow-through exposure system is used to investigate the effects of suspended ...

Experimental System of Solar Adsorption Refrigeration with Concentrated Collector

To improve the performance of solar adsorption refrigeration, an experimental system with a solar concentration collector was set up and investigated. The main components of the system were the adsorbent bed, the condenser, the evaporator, the cooling sub-system, and the solar collector. In the first step of the experiment, the vapor-saturated bed was heated by the solar radiation under closed conditions, which caused the bed temperature and pressure to increase. When the bed pressure became high enough, the bed was switched to connect to the condenser, thus water vapor flowed continually from the bed to the condenser to be liquefied. Next, the bed needed to cool down after the desorption. In the solar-shielded condition, achieved by aluminum foil, the circulating water loop was opened to the bed. With the water continually circulating in the bed, the stored heat in the bed was took out and the bed pressure decreased accordingly. When the bed pressure dropped below the saturation pressure at the evaporation temperature, the valve to the evaporator was opened. A mass of water vapor rushed into the bed and was adsorbed by the zeolite material. With the massive vaporization of the water in the evaporator, the refrigeration effect was generated finally. The experimental result has revealed that both the COP (coefficient of the performance of the system) and the SCP (specific cooling power of the system) of the SAPO-34 zeolite was greater than that of the ZSM-5 zeolite, no matter whether the adsorption time was longer or shorter. The system of the SAPO-34 zeolite generated a maximum COP of 0.169.

With solar energy as the driving force, a novel adsorption refrigeration system has been developed and experimentally investigated. Water vapor and zeolite formed the working pair of the adsorption system. This manuscript describes the setup of the experimental rig, the operation procedure, and the important results.

To improve the performance of solar adsorption refrigeration, an experimental system with a solar concentration collector was set up and investigated. The ...

Adherence of Bacteria to Plant Surfaces Measured in the Laboratory

This manuscript describes a method to measure bacterial binding to axenic plant surfaces in the light microscope and through the use of viable cell counts. Plant materials used include roots, sprouts, leaves, and cut fruits. The methods described are inexpensive, easy, and suitable for small sample sizes. Binding is measured in the laboratory and a variety of incubation media and conditions can be used. The effect of inhibitors can be determined. Situations that promote and inhibit binding can also be assessed. In some cases it is possible to distinguish whether various conditions alter binding primarily due to their effects on the plant or on the bacteria.

An easy method for measuring and characterizing bacterial adhesion to plants, particularly roots and sprouts, is described in this article.

This manuscript describes a method to measure bacterial binding to axenic plant surfaces in the light microscope and through the use of viable cell ...

Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

Dimethylated thioarsenicals such as dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV), which are produced by the metabolic pathway of dimethylarsinic acid (DMAV) thiolation, have been recently found in the environment as well as human organs. DMMTAV and DMDTAV can be quantified to determine the ecological effects of dimethylated thioarsenicals and their stability in environmental media. The synthesis method for these compounds is unstandardized, making replicating previous studies challenging. Furthermore, there is a lack of information about storage techniques, including storage of compounds without species transformation. Moreover, because only limited information about synthesis methods is available, there may be experimental difficulties in synthesizing standard chemicals and performing quantitative analysis. The protocol presented herein provides a practically modified synthesis method for the dimethylated thioarsenicals, DMMTAV and DMDTAV, and will help in the quantification of species separation analysis using high performance liquid chromatography in conjunction with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The experimental steps of this procedure were modified by focusing on the preparation of chemical reagents, filtration methods, and storage.

Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

This article presents modified experimental protocols for dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV) synthesis, inducing dimethylarsinic acid (DMAV) thiolation through mixing of DMAV, Na2S, and H2SO4. The modified protocol provides an experimental guideline, thereby overcoming limitations of the synthesis steps that could have caused experimental failures in quantitative analysis.

Dimethylated thioarsenicals such as dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV), which are produced by the metabolic ...

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol for performing in situ juvenile exposure tests within oligotrophic river catchments over one-month and three-month periods. Two methods (in both modifications) are presented to evaluate the juvenile growth and survival rate. The methods and modifications differ in value for the locality bioindication and each has its benefits as well as limitations. The sandy cage method works with a large set of individuals, but only some of the individuals are measured and the results are evaluated in bulk. In the mesh cage method, the individuals are kept and measured separately, but a low individual number is evaluated. The open water exposure modification is relatively easy to apply; it shows the juvenile growth potential of sites and can also be effective for water toxicity testing. The within-bed exposure modification needs a high workload but is closer to the conditions of a natural juvenile environment and it is better for reporting the real suitability of localities. On the other hand, more replications are needed in this modification due to its high-hyporheic environment variability.

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

In situ bioindications enable determination of the suitability of an environment for endangered mussel species. We describe two methods based on the juvenile exposure of freshwater pearl mussels in cages to oligotrophic river habitats. Both methods are implemented in variants for open water and hyporheic water environments.

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol ...