This study was supported by the Open Source Consortium of Instrumentation (Open-It), Japan, JSPS KAKENHI Grant (Nos. 22244019, 26610055, 15H04769 and 19H04492).

The protocol was conducted following the guidelines of the research ethics committee at the National Cancer Center Hospital East, Japan.
1. Monitoring of sealed radiation source in experiment room at RI facility
<ol>
	<li>Set the Compton camera beside the dose rate monitor as shown in Figure 2a. Set the height of the detectors from the ground to 2.5 m. Build the dose rate monitor, which consists of a parallel plate ionization chamber, into the upper part of the entrance of the experiment room at the RI facility to monitor the air dose rate of the position at intervals of 1 min.</li>
	<li>Turn on the power of the Compton camera and online computer.</li>
	<li>Start the simultaneous measurement with Compton camera and the dose rate monitor.</li>
	<li>Set a 137Cs sealed source (3.85 MBq) at a position labelled &#39;A&#39; in Figure 2a and leave it for 30 min. Set the distance between the detector and the sealed source to 3.6 m.</li>
	<li>Move the sealed source to a position labelled &#39;B&#39; and leave it during 30 min. Set the distance between the detector and the sealed source to 6.7 m.</li>
	<li>Move the sealed source at a position labelled &#39;C&#39; and leave it during 30 min. Set the distance between the detector and the sealed source to 6.7 m.</li>
	<li>Move the sealed source at a position labelled &#39;D&#39; and leave it during 30 min. Set the distance between the detector and the sealed source to 1 m.</li>
	<li>Move the sealed source outside the room. After 30 min, stop all measurement.</li>
</ol>
2. Environmental monitoring in PET facility
<ol>
	<li>Set the Compton camera in front of reception desk in PET facility as shown in Figure 2b. Set the height of the detectors from the ground to 1 m.</li>
	<li>Set the online computer in the staff room.</li>
	<li>Turn on the power of the Compton camera and online computer.</li>
	<li>Start Compton camera measurement early in the morning before patients arrive at facility.</li>
	<li>After all patients leave for the day, stop all measurement.</li>
</ol>
3. Outdoor measurement in Kawamata-machi, Fukushima, Japan
<ol>
	<li>Set the Compton camera near a private house as shown in Figure 2c, where the existence of some radiological Caesium hot spots with surface dose rates of 1 &#181;Sv/h or less are suspected. Set the height of the detectors from the ground to 1.5 m.</li>
	<li>Turn on the power of the Compton camera and online computer.</li>
	<li>Start Compton camera measurement.</li>
	<li>After 30 min, stop all measurement.</li>
</ol>

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The authors have nothing to disclose.

We presented three experimental protocols for visualizing various low-level gamma radiation sources using the omnidirectional Compton camera that we developed. The representative results demonstrated that gamma-ray imaging at low radiation levels permits derivation of novel and useful information on the surrounding environment. In the RI facility, the protocol revealed that our Compton camera system successfully discovers the position of the gamma-ray source, as well as the counting rate at the given position relative to the source. This means that the proposed method can serve as a next-generation technology for environmental radiation monitoring, replacing conventional stationary dose rate monitors already mounted on the walls of almost any RI facility. In this paper, we depicted gamma-ray intensity as a red field mapping the region experiencing intensities in the upper half of observed values (Figure 3, Figure 5, and Figure 6), so as to suit various purposes without bias. An approach that rather gives priority to a peak intensity, rather than to the distribution of gamma-ray sources, would adopt a narrower range of the red field, perhaps the upper quarter of observed values, in order to enable directive findings at shorter timescales. Indeed, in Figure 3c, the peak direction could be identified with a measurement time of 30 s for case (i) as shown in Figure 4, for which the peak position&#39;s intensity was around 20 counts.
As for environmental monitoring in the PET facility, the protocol demonstrated the possibility of visualizing the radioactivity movement through the facility, which in this case is considered to be the movement of a patient injected with 18F-FDG. In Figure 5d,e, the direction of the patient can be identified in less than 10 s by adopting the narrower red field range as mentioned above. In the future, the environmental monitoring of gamma-ray sources by animation would be useful for various situations, not only for the movement of patients as in this study, but also for monitoring the transfer of nuclear fuel materials such as in airports for purposes of terrorism, by taking advantage of the high-sensitivity and low-cost characteristics of the system, although the energy resolution of a system that uses a scintillator is inferior to that of more expensive semiconductor detectors, such as high purity germanium (HPGe) and CdZnTe (CZT).
In the Fukushima field, the protocol successfully visualized the extended gamma radiation source with surface dose rates of much less than 1 &#956;Sv/h, which is an order of magnitude lower than that in a recent report25,26. Our Compton camera system was found to be capable of operating stably and robustly for outdoor measurement. We have already confirmed that the system can be operated by using WiFi and portable battery for more convenient use in various situations, especially for outdoor measurement. The Ministry of Environment in Japan has set the air dose rate minimum at 0.23 &#956;Sv/h to designate areas to be decontaminated. We believe that our system and protocols will be a great help for the decontamination procedure in areas of low-level radioactive contamination in broad areas of eastern Japan where radioactive cesium was released by the Fukushima Daiichi nuclear power plant accident in 2011.
The Compton camera used in this study has high sensitivity for gamma rays with energies between 300 keV and 1400 keV, attributable to the use of 3.5 cm CsI(Tl) scintillator cubes18. Scintillator type and size can be optimized for environmental monitoring of low-level gamma radiation sources below 300 keV, such as 99mTc (141 keV) and 111In (171 keV, 245 keV), which are frequently used in scintigraphy. This work will be presented in another paper in the near future. The detector can be manufactured at a low price. In fact, the cost of the detector materials used in this study was no more than $20,000, and this amount was dominated by the price of the counter consisting of CsI (Tl) and PMT; this configuration is significantly less expensive than the GAGG scintillators and HPGe semiconductor detectors that are used in other Compton cameras. Furthermore, the system used in this study should be made more compact for the sake of versatility and convenience. The size of the system produced in this study was 30 cm x 25 cm x 40 cm, which is larger than the existing portable gamma camera5,27. The main reasons for such large system size are the large size of the PMT attached to CsI (Tl) (&#966;4 cm &#215; 12 cm) and the large electronics handmade by us. In the future, portability will be improved by replacing the PMT with a metal package PMT or Silicon Photomultiplier (SiPM) as well as by repackaging the electronics at small size.

Medical facilities house various low-level gamma radiation sources with a surface and/or air dose rate of just a few &#181;Sv/h. Such sources are also present across broad areas of eastern Japan exhibiting low-level radioactive contamination by radioactive cesium from the Fukushima Daiichi nuclear power plant accident in 2011. These environments sometimes expose workers to the external irradiation exposure limit for the human body for the general population as advised by the International commission on radiological protection (ICRP): 1 mSv/year (e.g., 1 &#956;Sv/h for 4 h per day, 250 days per year)1. If radiation sources are visualized from more than a few meters in advance on short timescales, the amount of radiation exposure can be reduced. One of the best solutions for visualizing these gamma radiation sources is to adopt a gamma-ray imaging Compton camera technique2. In this technique, the energy and cone-direction of incident gamma-rays emitted from the radiation source are measured by the detector for each event, and then the gamma-ray source direction can be reconstructed by back-projection3. Previous studies have developed Compton camera systems aimed at the application of a new diagnostic device in nuclear medicine and/or a new gamma-ray telescope in astrophysics4,5,6,7,8,9,10,11,12,13,14, as well as image reconstruction techniques for Compton cone data by analytical15,16 and statistical17 approaches. More expensive, state-of-the-art devices with complicated electronics are often adopted to obtain high angular resolution within a standard deviation of a few degrees, but this precision makes it difficult to simultaneously achieve high detection efficiency.
Recently, we have proposed and developed a low-cost, high-sensitivity, omnidirectional gamma-ray imaging Compton camera18, based on a two-fold coincidence within a number of independent scintillators that act as either scatterers or absorbers19. The aim of this technique is to easily achieve high detection efficiency with an angular resolution s of ~10 degrees or less, which is adequate for an environmental monitor. This is accomplished through the application of an image-sharpening technique18,20 based on the filtered back-projection algorithm, which applies a convolution filter used in image reconstruction for computed tomography to the Compton reconstruction. Furthermore, the detection efficiency, angular resolution and dynamic range of the detector can be easily optimized when the type, size and arrangement of scintillators are coordinated in accordance with a particular purpose, such as usage in environments emitting elevated radioactivity21,22.
In this study, we present experimental protocols for various trials for visualizing low-level gamma-ray radiation sources using this omnidirectional Compton camera technique in a radioisotope (RI) facility, a positron emission tomography (PET) facility and the Fukushima field. We prepared and utilized the omnidirectional gamma-ray imaging Compton camera previously developed by ourselves18 but with some improvements, in order to achieve higher detection efficiency. Figure 1 shows a schematic view of the arrangement of CsI(Tl) scintillators of eleven elements used in this study. The eleven counters consist of two layers; two counters at the center and nine counters in a half-circle, considering forward and backward scattering configurations. Each CsI(Tl) scintillator cube of 3.5 cm was read out with super-bialkali photo-multiplier tubes (PMT). The signals were fed into a flash ADC board with SiTCP technology23 and the front end was connected to a PC via Ethernet. An online program created using Visual C++ with ROOT library24 was operated on a Windows PC. A gamma-ray image was reconstructed and sharpened18,20 on a spherical surface with accumulating rings with a radius of &#952; that is a scattering angle calculated from Compton kinematics for each two-fold coincidence event. An omnidirectional gamma-ray image can be displayed both online and offline by superimposition on the omnidirectional optical image previously taken by a digital camera. During the measurement, the trigger rate, total energy spectrum (the sum of the energy deposits for each two-fold coincidence event), and the reconstructed images of a preset gamma-ray energy can be displayed on the online PC screen. This information can be updated at a preset time interval (e.g., every 10 s). Here, we set the screen to display two types of reconstructed images: an image that is accumulated at the start of the measurement and an image reaccumulated at every preset time interval (e.g., every 1 min). Furthermore, because the raw data for each event obtained using the measurements are stored, it is possible to reanalyze the data after the measurements and then regenerate a reconstructed image for an arbitrary gamma-ray energy at an arbitrary time interval. Table 1 shows the performance of the Compton camera system used in this study, by comparison with the previous six-counter system18. The comparison revealed that a sub-MeV gamma-ray source was successfully visualized with a detection efficiency twice that of the previous system, while maintaining the angular resolution s of ~11 degrees. We also confirmed that the angular dependence of acceptance was kept to a minimum, showing differences of s ~ 4%. The details on the fundamental techniques of the system are described in Watanabe et al. (2018)18. Here we introduce three experimental protocols for visualizing various low-level gamma-ray radiation sources using the Compton camera described above.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Compton camera</td>
			<td></td>
			<td></td>
			<td>Custom made</td>
		</tr>
		<tr>
			<td>Dose rate monitor</td>
			<td>Hitachi, Ltd.</td>
			<td>DAM-1102</td>
			<td></td>
		</tr>
		<tr>
			<td>Flash ADC board</td>
			<td>Bee Beans Technologies Co.,Ltd.</td>
			<td>BBT-019</td>
			<td></td>
		</tr>
		<tr>
			<td>PC</td>
			<td>Panasonic Corporation</td>
			<td>CF-SZ6</td>
			<td></td>
		</tr>
		<tr>
			<td>Photo-multiplier tube</td>
			<td>Hamamatsu Photonics K.K.</td>
			<td>H11432-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Survey meter</td>
			<td>Fuji Electric Co., Ltd.</td>
			<td>NHC7</td>
			<td></td>
		</tr>
	</tbody>
</table>

visualization of low-level gamma radiation sources using a low-cost, high-sensitivity, omnidirectional compton camera

We present experimental protocols for visualizing various low-level gamma radiation sources in the ambient environment. Experiments were conducted by using a low-cost, high-sensitivity, omnidirectional, gamma-ray imaging Compton camera. In the laboratory, the position of a sub-MeV gamma radiation source such as 137Cs can easily be monitored via omnidirectional gamma-ray imaging obtained by the Compton camera. In contrast, a stationary, wall-mounted dose rate monitor cannot always successfully monitor such a source. Furthermore, we successfully demonstrated the possibility of visualizing the radioactivity movement in the environment, for example, the movement of a patient injected with 18F-fluorodeoxyglucose (18F-FDG) in a nuclear medicine facility. In the Fukushima field, we easily obtained omnidirectional gamma-ray images concerned with the distribution on the ground of low-level radioactive contamination by radioactive cesium released by the Fukushima Daiichi nuclear power plant accident in 2011. We demonstrate clear advantages of using our procedure with this camera to visualize gamma-ray sources. Our protocols can further be used to discover low-level gamma radiation sources, in place of stationary dose rate monitors and/or portable survey meters used conventionally.

Monitoring of sealed radiation source in experiment room at RI facility 
Figure 3a shows the time variation of trigger rate measured by the Compton camera (black solid line), after applying a time-lag selection of two-hit counters less than 1 &#956;s. The trigger rate changed every 30 min depending on the position of the sealed source (i.e., distance from the position to the camera). This variation was confirmed from the data measured by the stationary dose rate monitor (blue dashed line); the behavior remained constant (i.e., background level) other than between 5750 s and 7800 s. Here, we tentatively set five periods labelled (i), (ii), (iii), (iv) and (v), representing the five positions of the sealed source (Figure 3a). Figure 3b shows the total energy spectra for each such period (30 min for each), the horizontal axis representing the sum of energy deposits for each two-fold coincidence event. We note 662 keV photo-absorption peaks originating from the 137Cs sealed source for (i), (ii), (iii) and (iv), while (v) shows only background levels. Peak heights for (ii) and (iii) are the same, which we attribute to the same 6.7 m distance from the camera to the sealed source. By selecting the event within 662&#177;40 keV for 662 keV, we calculated the scattering angles and reconstructed the omnidirectional gamma-ray image. The results are shown in Figures 3c-f, respectively, for periods (i), (ii), (iii) and (iv). Here gamma-ray images are indicated by the red region, which indicates gamma-ray intensities in the upper half of the observed range. We find that the position of the 137Cs sealed source can be successfully identified from the gamma-ray images. Figure 4 shows the changes in the image with integration time, where the red field instead corresponds to a narrower range (the upper 30%) of the observed range. This narrower range was adopted in order to give priority to a peak intensity. In this case, 137Cs source direction could be identified after 30 s.
Environmental monitoring in PET facility 
Figure 5a shows the overall time variation of the trigger rate during the daytime (5.6 h) as measured by the Compton camera (black line) in front of a reception desk in a PET facility. We observe remarkable enhancement in the trigger rate with various patterns, which could be attributed to the movement of patients injected with 18F-fluorodeoxyglucose (18F-FDG) around the reception desk. As an example of such patterns, we focus on the period from 6200 s to 7000 s. According to the trigger rate in this period shown in Figure 5b, a series of enhancements are apparent, with two plateaus labelled (i) and (ii). Figure 5c shows the total energy spectra for Figure 5b&#39;s periods (i), (ii) and (iii). We observe 511 keV photo-absorption peaks originating from the 18F-FDG. Figure 5d,e show the 511 keV gamma-ray omnidirectional image in periods (i) and (ii), respectively, in which we selected events within 511&#177;40 keV for image reconstruction. The directions of gamma-ray peaks in both figures correspond respectively to the directions of the sofa and the restroom behind the wall. Considering the trigger rates of both (i) and (ii), we interpret the gamma-rays in (i) as leakage penetrating the shield of the wall from the restroom; we presume that a patient entered the restroom and spent two minutes, and after that sat on the sofa a few minutes before the PET scan.
Outdoor measurement in Kawamata-machi, Fukushima, Japan 
Figure 6a shows the time variation of the trigger rate for 30 min of outdoor measurement. The stability of the trigger rate implies that our Compton camera system operates stably even for measurements conducted outdoors over a long period. To demonstrate how the extended gamma-ray source was reconstructed, we set four different integration periods labelled (i) (1 min), (ii) (10 min), (iii) (20 min) and (iv) (30 min), as shown in Figure 6a. Figure 6b shows the total energy spectra for each period, depicting the structures superimposed on the photo-absorption peaks of gamma-rays emitted from radioactive nuclides at 605 keV and 796 keV for 134Cs and 662 keV for 137Cs. To reconstruct the gamma-ray image, we selected events within 565-622 keV for 605 keV, 662&#177;40 keV for 662 keV and 796&#177;40 keV for 796 keV. The gamma-ray omnidirectional images for 605, 662 and 796 keV are shown in Figures 6c-f for integration periods (i), (ii), (iii) and (iv), respectively. In this case, we find that the reconstructed gamma-ray distribution is stable as long as the integration time exceeds 20 min. The slope of a hill in front and the lower part of rain gutter are clearly contaminated, while the area covered with uncontaminated soil in the right part of image is demonstrably not contaminated. The gamma-ray intensity is in good agreement with dose rate values measured by a scintillation-type survey meter, the values of which are shown in yellow in Figure 6f.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/60463/60463fig1.jpg" /> 
Figure 1: Omnidirectional Gamma-ray imaging Compton camera system. (a) Geometrical arrangement of scintillators with eleven elements used in this study. Two scintillators were arranged at the center of a circle, with nine more arranged in a half-circle, staggered vertically. (b) Photograph of the detector without housing. The counters were fixed inside an expanded polystyrene. <a href="https://www.jove.com/files/ftp_upload/60463/60463fig1alarge.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/60463/60463fig2.jpg" /> 
Figure 2: Experimental setup. (a) Monitoring of a sealed radiation source in the experiment room at the RI facility, where a 137Cs-sealed source was sequentially set at the positions labelled &#39;A&#39;, &#39;B&#39;, &#39;C&#39; and &#39;D&#39;. (b) Environmental monitoring in front of a reception desk in the PET facility. (c) Outdoor measurement in the Fukushima field, Japan. The Compton camera was fixed on a stepladder. <a href="https://www.jove.com/files/ftp_upload/60463/60463fig2alarge.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/60463/60463fig3.jpg" /> 
Figure 3: Representative results of the monitoring of a 137Cs-sealed source in the experiment room. (a) Time variation of the trigger rate as measured by the Compton camera (black solid line) and of the air dose rate as measured by the stationary dose rate monitor (blue dashed line). (b) Total energy spectra (the sum of energy deposits for each two-fold coincidence event) in Figure 3a&#39;s periods (i) (red line), (ii) (blue line), (iii) (green line), (iv) (pink line) and (v) (black line), with the result of (iv) was scaled by 0.15. (c) 662 keV gamma-ray omnidirectional image superimposed on the optical image in period (i) (30 min). The red field indicates gamma-ray intensities in the upper half of the observed range. (d) Same as (c) but for period (ii) (30 min). (e) Same as (c) but for period (iii) (30 min). (f) Same as (c) but for period (iv) (30 min). <a href="https://www.jove.com/files/ftp_upload/60463/60463fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/60463/60463fig4.jpg" /> 
Figure 4: Same as Figure 3c, but with various measurement times: 3 s, 5 s, 10 s, 15 s, 30 s, and 60 s. Here gamma-ray images are identified by the red region, which indicates gamma-ray intensities in the upper 30% of the observed range. <a href="https://www.jove.com/files/ftp_upload/60463/60463fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/60463/60463fig5.jpg" /> 
Figure 5: Representative results of environmental monitoring in front of a reception desk in the PET facility. (a) Time variation of the trigger rate as measured by the Compton camera (black line) during the daytime (5.6 h). (b) Trigger rate detailed for a period between 6200 s and 7000 s in (a). (c) Total energy spectra for Figure 4b&#39;s periods (i) (red line), (ii) (blue line) and (iii) (black line). (d) 511 keV gamma-ray omnidirectional image superimposed on the optical image for period (i) (2 min). (e) Same as (d) but for period (ii) (2 min). <a href="https://www.jove.com/files/ftp_upload/60463/60463fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/60463/60463fig6.jpg" /> 
Figure 6: Representative results of outdoor measurement in Kawamata-machi, Fukushima, Japan. (a) Time variation of the trigger rate as measured by the Compton camera (black solid line). (b) Total energy spectra for Figure 5a&#39;s periods (i) 1 min (blue line), (ii) 10 min (green line), (iii) 20 min (red line) and (iv) 30 min (black line). (c) Omnidirectional image of 605, 662 and 796 keV gamma-rays superimposed on the optical image for period (i) (1 min). (d) Same as (c) but for period (ii) (10 min). (e) Same as (c) but for period (iii) (20 min). (f) Same as (c) but for period (iv) (30 min). The dose rate values measured by a scintillation-type survey meter at a height of 1 cm from the ground are shown in the figures for comparison. <a href="https://www.jove.com/files/ftp_upload/60463/60463fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1">
	<tbody>
		<tr>
			<td></td>
			<td>This study</td>
			<td>Previous study18</td>
		</tr>
		<tr>
			<td>Number of counters</td>
			<td>11</td>
			<td>6</td>
		</tr>
		<tr>
			<td>Detection efficiency (cps/(&#956;Sv/h)) for 511 keV gamma-rays</td>
			<td>36</td>
			<td>18</td>
		</tr>
		<tr>
			<td>Angular resolution &#963; (deg)*</td>
			<td>11</td>
			<td>11</td>
		</tr>
	</tbody>
</table>
Table 1: Performances of present and previous Compton camera systems. *The angular resolution was estimated from 511 keV omnidirectional gamma ray images obtained during measurement of a 22Na sealed source (0.8MBq) placed 1 m ahead of the detector.

Watch this Scientific Journal Video about Visualization of Low-Level Gamma Radiation Sources Using a Low-Cost, High-Sensitivity, Omnidirectional Compton Camera at JoVE.com

Visualization of Low-Level Gamma Radiation Sources Using a Low-Cost, High-Sensitivity, Omnidirectional Compton Camera

We present experimental protocols for visualizing various low-level gamma radiation sources in the ambient environment using a low-cost, high-sensitivity, omnidirectional, gamma-ray imaging Compton camera.

We present experimental protocols for visualizing various low-level gamma radiation sources in the ambient environment. Experiments were conducted by ...

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12.3K Views.  Kitasato University. We present experimental protocols for visualizing various low-level gamma radiation sources in the ambient environment using a low-cost, high-sensitivity, omnidirectional, gamma-ray imaging Compton camera.

Video: Visualization of Low-Level Gamma Radiation Sources Using a Low-Cost, High-Sensitivity, Omnidirectional Compton Camera

Pretreatment of Lignocellulosic Biomass with Low-cost Ionic Liquids

A number of ionic liquids (ILs) with economically attractive production costs have recently received growing interest as media for the delignification of a variety of lignocellulosic feedstocks. Here we demonstrate the use of these low-cost protic ILs in the deconstruction of lignocellulosic biomass (Ionosolv pretreatment), yielding cellulose and a purified lignin. In the most generic process, the protic ionic liquid is synthesized by accurate combination of aqueous acid and amine base. The water content is adjusted subsequently. For the delignification, the biomass is placed into a vessel with IL solution at elevated temperatures to dissolve the lignin and hemicellulose, leaving a cellulose-rich pulp ready for saccharification (hydrolysis to fermentable sugars). The lignin is later precipitated from the IL by the addition of water and recovered as a solid. The removal of the added water regenerates the ionic liquid, which can be reused multiple times. This protocol is useful to investigate the significant potential of protic ILs for use in commercial biomass pretreatment/lignin fractionation for producing biofuels or renewable chemicals and materials.

The pretreatment of lignocellulosic biomass with protic low-cost ionic liquids is shown, resulting in a delignified cellulose-rich pulp and a purified lignin. The pulp gives rise to high glucose yields after enzymatic saccharification.

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On-Site Molecular Detection of Soil-Borne Phytopathogens Using a Portable Real-Time PCR System

On-site diagnosis of plant diseases can be a useful tool for growers for timely decisions enabling the earlier implementation of disease management strategies that reduce the impact of the disease. Presently in many diagnostic laboratories, the polymerase chain reaction (PCR), particularly real-time PCR, is considered the most sensitive and accurate method for plant pathogen detection. However, laboratory-based PCRs typically require expensive laboratory equipment and skilled personnel. In this study, soil-borne pathogens of potato are used to demonstrate the potential for on-site molecular detection. This was achieved using a rapid and simple protocol comprising of magnetic bead-based nucleic acid extraction, portable real-time PCR (fluorogenic probe-based assay). The portable real-time PCR approach compared favorably with a laboratory-based system, detecting as few as 100 copies of DNA from Spongospora subterranea. The portable real-time PCR method developed here can serve as an alternative to laboratory-based approaches and a useful on-site tool for pathogen diagnosis.

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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.

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Measuring the Flight Ability of the Ambrosia Beetle, Platypus Quercivorus (Murayama), Using a Low-Cost, Small, and Easily Constructed Flight Mill

The ambrosia beetle, Platypus quercivorus (Murayama), is the vector of a fungal pathogen that causes mass mortality of Fagaceae trees (Japanese oak wilt). Therefore, knowing the dispersal capacity may help inform trapping/tree removal efforts to prevent this disease more effectively. In this study, we measured the flight velocity and duration and estimated the flight distance of the beetle using a newly developed flight mill. The flight mill is low cost, small, and constructed using commonly available items. Both the flight mill arm and its vertical axis comprise a thin needle. A beetle specimen is glued to one tip of the arm using instant glue. The other tip is thick due to being covered with plastic, thus it facilitates the detection of rotations of the arm. The revolution of the arm is detected by a photo sensor mounted on an infrared LED, and is indicated by a change in the output voltage when the arm passed above the LED. The photo sensor is connected to a personal computer and the output voltage data are stored at a sampling rate of 1 kHz. By conducting experiments using this flight mill, we found that P. quercivorus can fly at least 27 km. Because our flight mill comprises cheap and small ordinary items, many flight mills can be prepared and used simultaneously in a small laboratory space. This enables experimenters to obtain a sufficient amount of data within a short period.

Measuring the Flight Ability of the Ambrosia Beetle, Platypus Quercivorus Murayama, Using a Low-Cost, Small, and Easily Constructed Flight Mill

We developed a low cost and small flight mill, constructed with commonly available items and easily used in experimentation. Using this apparatus, we measured the flight ability of an ambrosia beetle, Platypus quercivorus.

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Methods for Image-based Surveys of Benthic Macroinvertebrates and Their Habitat Exemplified by the Drop Camera Survey for the Atlantic Sea Scallop

Underwater imaging has long been used in the field of marine ecology but decreasing costs of high-resolution cameras and data storage have made the approach more practical than in the past. Image-based surveys allow for initial samples to be revisited and are non-invasive compared to traditional survey methods that typically involve nets or dredges. Protocols for image-based surveys can vary greatly but should be driven by target species behavior and survey objectives. To demonstrate this, we describe our most recent methods for an Atlantic sea scallop (Placopecten magellanicus) drop camera survey to provide a procedural example and representative results. The procedure is divided into three critical steps that include survey design, data collection, and data products. The influence of scallop behavior and the survey goal of providing an independent assessment of the U.S. sea scallop resource on the survey procedure are then discussed in the context of generalizing the method. Overall, the broad applicability and flexibility of the University of Massachusetts Dartmouth School for Marine Science and Technology (SMAST) drop camera survey demonstrates the method could be generalized and applied to a variety of sessile invertebrates or habitat focused research.

Image based surveying is an increasingly practical, non-invasive method to sample the marine environment. We present the protocol of a drop camera survey that estimates the abundance and distribution of the Atlantic sea scallop (Placopecten magellanicus). We discuss how this protocol can be generalized for application to other benthic macroinvertebrates.

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A Flexible Low Cost Hydroponic System for Assessing Plant Responses to Small Molecules in Sterile Conditions

A wide range of studies in plant biology are performed using hydroponic cultures. In this work, an in vitro hydroponic growth system designed for assessing plant responses to chemicals and other substances of interest is presented. This system is highly efficient in obtaining homogeneous and healthy seedlings of the C3 and C4 model species Arabidopsis thaliana and Setaria viridis, respectively. The sterile cultivation avoids algae and microorganism contamination, which are known limiting factors for plant normal growth and development in hydroponics. In addition, this system is scalable, enabling the harvest of plant material on a large scale with minor mechanical damage, as well as the harvest of individual parts of a plant if desired. A detailed protocol demonstrating that this system has an easy and low-cost assembly, as it uses pipette racks as the main platform for growing plants, is provided. The feasibility of this system was validated using Arabidopsis seedlings to assess the effect of the drug AZD-8055, a chemical inhibitor of the target of rapamycin (TOR) kinase. TOR inhibition was efficiently detected as early as 30 min after an AZD-8055 treatment in roots and shoots. Furthermore, AZD-8055-treated plants displayed the expected starch-excess phenotype. We proposed this hydroponic system as an ideal method for plant researchers aiming to monitor the action of plant inducers or inhibitors, as well as to assess metabolic fluxes using isotope-labeling compounds which, in general, requires the use of expensive reagents.

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Quantifying Plant Soluble Protein and Digestible Carbohydrate Content, Using Corn Zea mays As an Exemplar

The protocols described herein provide a clear and approachable methodology for measuring soluble protein and digestible (non-structural) carbohydrate content in plant tissues. The ability to quantify these two plant macronutrients has significant implications for advancing the fields of plant physiology, nutritional ecology, plant-herbivore interactions and food-web ecology.

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Construction of a Compact Low-Cost Radiation Shield for Air-Temperature Sensors in Ecological Field Studies

Low cost temperature sensors are increasingly used by ecologists to assess climatic variation and change on ecologically relevant scales. Although cost-effective, if not deployed with proper solar radiation shielding, the observations recorded from these sensors will be biased and inaccurate. Manufactured radiation shields are effective at minimizing this bias, but are expensive compared to the cost of these sensors. Here, we provide a detailed methodology for constructing a compact version of a previously described custom fabricated radiation shield, which is more accurate than other published shielding methods that attempt to minimize shield size or construction costs. The method requires very little material: corrugated plastic sheets, aluminum foil duct tape, and cable ties. One 15 cm and two 10 cm squares of corrugated plastic are used for each shield. After cutting, scoring, taping and stapling of the sheets, the 10 cm squares form the bottom two layers of the solar radiation shield, while the 15 cm square forms the top layer. The three sheets are held together with cable ties. This compact solar radiation shield can be suspended, or placed against any flat surface. Care must be taken to ensure that the shield is completely parallel to the ground to prevent direct solar radiation from reaching the sensor, possibly causing increased warm biases in sun-exposed sites in the morning and afternoon relative to the original, larger design. Even so, differences in recorded temperatures between the smaller, compact shield design and the original design were small (mean daytime bias = 0.06 &#176;C). Construction costs are less than half of the original shield design, and the new design results in a less conspicuous instrument that may be advantageous in many field ecology settings.

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Communities of nonvascular cryptogams, such as mosses or lichens, are an important part of the Earth's biodiversity, contributing to the regulation of the carbon and nitrogen cycles in many ecosystems. Being poikilohydric organisms, they do not actively control their internal water content and need a humid environment to activate their metabolism. Therefore, studying water relationships of nonvascular cryptogams is crucial to understand both their diversity patterns and their functions in the ecosystems. We present the BtM datalogger, a low-cost open-source platform for the study of the water content of nonvascular cryptogams. The datalogger is designed to measure ambient temperature, humidity, and conductance from up to eight samples simultaneously. We provide a design for a printed circuit board (PCB), a detailed protocol to assemble the components, and the required source code. All this makes the assembly of the BtM datalogger accessible to any research group, even to those without previous specialized knowledge. Therefore, the design presented here has the potential to help popularize the use of this type of device among ecologists and field biologists.

We present a simple and cost-effective method to build an open-source datalogger that measures the conductance of nonvascular cryptogams together with the environmental temperature and humidity. We describe the hardware design of the datalogger and provide step-by-step assembly instructions, the list of required open-source logging software, the code to run the datalogger, and a calibration protocol.

Communities of nonvascular cryptogams, such as mosses or lichens, are an important part of the Earth's biodiversity, contributing to the regulation of the ...