Name: a uniaxial compression experiment with co2-bearing coal using a visualized and constant-volume gas-solid coupling test system
Uploaded: 2019-06-12T13:00:00
Description: Watch this Scientific Journal Video about A Uniaxial Compression Experiment with CO2-Bearing Coal Using a Visualized and Constant-Volume Gas-Solid Coupling Test System at JoVE.com

This work was supported by the China National Major Scientific Instruments Development Project (Grant No. 51427804) and the Shandong Province National Natural Science Foundation (Grant No. ZR2017MEE023).

1. Sample preparation
<ol>
	<li>Collect raw coal blocks from the 4671B6 working face from the Xinzhuangzi coal mine. Note that, due to the low strength and looseness of the structure, the raw coal is broken and probably mixed with impurities. To avoid the influence of these internal and external factors, as well as reduce the inhomogeneity of coal as much as possible, select large coal blocks (about 15 cm long, 10 cm wide, and 10 cm high).</li>
	<li>Use a tweezer to remove impurities mixed in the coal and scrub the cru...

<ol>
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Considering the danger of high-pressure gas, some critical steps are important during the test. The valves and O rings should be inspected and replaced regularly, and any source of ignition should not be allowed in the laboratory. When using the manual pressure-regulating valve, the experimenter should twist the valve slowly to make the pressure in the visualized vessel increase gradually. Do not disassemble the vessel during the test. When the experiment is finished, the back door of the vessel should be opened after th...

The increasing concentration of CO2 in the atmosphere is a direct factor causing the global warming effect. Due to the strong sorption capacity of coal, CO2 sequestration in a coal seam is regarded as a practical and environment-friendly means to reduce the global emission of greenhouse gas1,2,3. At the same time, the injected CO2 can replace CH4 and result in gas production promotion in coalbed methane recovery (ECBM)4,5,6. The ecological and economic prospects of CO2 sequestration have recently attracted worldwide attention among researchers, as well as among different international environmental protection groups and governmental agencies.
Coal is a heterogeneous, structurally anisotropic rock composed of a pore, fracture, and coal matrix. The pore structure&#160;has a large specific surface area, which can adsorb a large amount of gas, playing a vital role in gas sequestration, and the fracture is the main path for free gas flow7,8. This unique physical structure leads to a great gas adsorption capacity for CH4 and CO2. Mine gas is deposited in coalbed in a few forms: (1) adsorbed on the surface of micropores and larger pores; (2) absorbed in the coal molecular structure; (3) as free gas in fractures and larger pores; and (4) dissolved in deposit water. The sorption behavior of coal to CH4 and CO2 causes matrix swelling, and further studies demonstrate that it is a heterogeneous process and is related to the coal lithotypes9,10,11. In addition, gas sorption can result in damage in the constitutive relation of coal12,13,14.
The raw coal sample is generally used in coal and CO2 coupling experiments. Specifically, a large piece of raw coal from the working face in a coal mine is cut to prepare a sample. However, the physical and mechanical properties of raw coal inevitably have a high dispersion degree due to the random spatial distribution of natural pores and fractures in a coal seam. Moreover, the gas-bearing coal is soft and difficult to be reshaped. According to the principles of the orthogonal experimental method, the briquette, which is reconstituted with raw coal powder and cement, is regarded as an ideal material used in the coal sorption test15,16. Being cold-pressed with metal dies, its strength can be preset and remains stable by adjusting the quantity of cement, which benefits the comparative analysis of the single-variable effect. Additionally, although the porosity of the briquette sample is ~4-10 times, that of the raw coal sample, similar adsorption and desorption characteristics and stress-strain curve have been found in the experimental research17,18,19,20. In this paper, a scheme of a similar material for gas-bearing coal has been adopted to prepare the briquette21. The raw coal was taken from the 4671B6 working face in the Xinzhuangzi Coal Mine, Huainan, Anhui Province, China. The coal seam is approximately 450 m below ground level and 360 m below sea level, and it dips at about 15&#176; and is approximately 1.6 m in thickness. The height and diameter of the briquette sample are 100 mm and 50 mm, respectively, which is the recommended size suggested by the International Society for Rock Mechanics (ISRM)22.
The previous uniaxial or triaxial loading test instruments for gas-bearing coal experiments under laboratory conditions have some shortages and limitations, presented as fellows23,24,25,26,27,28: (1) during the loading process, the vessel volume decreases with the piston moving, causing fluctuations in gas pressure and disturbances in gas sorption; (2) the real-time image monitoring of samples, as well as circumferential deformation measurements in a high gas pressure environment, is difficult to conduct; (3) they are limited to stimulation of dynamic load disturbances on preloaded samples to analyze their mechanical response characteristics. In order to improve the instrument precision and data acquisition in the gas-solid coupling condition, a visualized and constant-volume test system29 has been developed (Figure 1), including (1) a visualized loading vessel with a constant volume chamber, which is the core component; (2) a gas filling module with a vacuum channel, two filling channels, and a releasing channel; (3) an axial loading module consisting of an electro-hydraulic servo universal testing machine and control computer; (4) a data acquisition module comprised of a circumferential displacement measurement apparatus, a gas pressure sensor, and a camera at the window of the visualized loading vessel.
The core visualized vessel (Figure 2) is specifically designed so that two adjusting cylinders are fixed on the upper plate and their pistons move simultaneously with the loading one through a beam, and the sectional area of the loading piston is equal to the sum of that of the adjusting cylinders. Flowing through an inner hole and soft pipes, the high-pressure gas in the vessel and the two cylinders is connected. Therefore, when the vessel-loading piston moves downward and compresses the gas, this structure can offset the change in volume and eliminate pressure interference. In addition, the enormous gas-induced counterforce exerting on the piston is prevented during the test, significantly improving the safety of the instrument. The windows, which are equipped with tempered borosilicate glass and situated on three sides of the vessel, provide a direct way to take a photograph of the sample. This glass has been successfully tested and proved to resist up to 10 MPa gas with a low expansion rate, high strength, light transmittance, and chemical stability29.
This paper describes the procedure to perform a uniaxial compression experiment of CO2-bearing coal with the new visualized and constant-volume gas-solid coupling test system, which includes the description of all pieces that prepare a briquette sample using raw coal powder and sodium humate, as well as the successive steps to inject high-pressure CO2 and conduct uniaxial compression. The whole sample deformation process is monitored using a camera. This experimental approach offers an alternative way to quantitively analyze the adsorption-induced damage and fracture evolution characteristic of gas-bearing coal.

<table>
	<tbody>
		<tr>
			<td>3Y-Leica MPV-SP photometer microphotometric system</td>
			<td>Leica,Germany</td>
			<td>M090063016</td>
			<td>Used for vitrinite 
			reflectance measurement</td>
		</tr>
		<tr>
			<td>Automatic isotherm adsorption instrument</td>
			<td>BeiShiDe Instrument Technology (Beijing)CO.,Ltd.</td>
			<td>3H-2000PH</td>
			<td>Isothermal adsorption test</td>
		</tr>
		<tr>
			<td>Electro hydraulic servo universal testing machine</td>
			<td>Jinan Shidaishijin testing machine CO.,Ltd</td>
			<td>WDW-100EIII</td>
			<td>Used to provide 
			axial pressure</td>
		</tr>
		<tr>
			<td>Gas pressure sensor</td>
			<td>Beijing Star Sensor Technology CO.,LTD</td>
			<td>CYYZ11</td>
			<td>Gas pressure monitoring</td>
		</tr>
		<tr>
			<td>Gas tank(carbon dioxide/helium)</td>
			<td>Heifei Henglong Gas.,Ltd</td>
			<td></td>
			<td>Gas resource</td>
		</tr>
		<tr>
			<td>high-speed camera</td>
			<td>Sony corporation</td>
			<td>FDR-AX30</td>
			<td>Image monitoring</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Yuyao YuanDong Digital Instrument Factory</td>
			<td>XGQ-2000</td>
			<td>Briquette drying</td>
		</tr>
		<tr>
			<td>jaw crusher</td>
			<td>Hebi Tianke Instrument CO.,Ltd</td>
			<td>EP-2</td>
			<td>Coal grinding</td>
		</tr>
		<tr>
			<td>Manual pressure reducing valve</td>
			<td>Shanghai Saergen Instrument CO.,Ltd</td>
			<td>R41</td>
			<td>Outlet gas pressure adjustment</td>
		</tr>
		<tr>
			<td>Proximate Analyzer</td>
			<td>Changsha Kaiyuan Instrument CO.,Ltd</td>
			<td>5E-MAG6700</td>
			<td>Coal industrial analysis</td>
		</tr>
		<tr>
			<td>Resistance strain gauge</td>
			<td>Jinan Sigmar Technology CO.,LTD</td>
			<td>ASMB3-16/8</td>
			<td>Poisson ratio measurement</td>
		</tr>
		<tr>
			<td>Sieve shaker (6,16mesh)</td>
			<td>Hebi Tianguan Instrument CO.,Ltd</td>
			<td>GZS-300</td>
			<td>Coal powder shelter</td>
		</tr>
		<tr>
			<td>Soft pipe</td>
			<td>Jinan Quanxing High pressure pipe CO.,Ltd</td>
			<td></td>
			<td>Inner diameter=5 mm 
			maximal pressure=30 MPa</td>
		</tr>
		<tr>
			<td>Standard rock sample circumferential deformation test apparatus</td>
			<td>Huainan Qingda Machinery CO.,Ltd</td>
			<td></td>
			<td>Circumferential deformation 
			acquisition</td>
		</tr>
		<tr>
			<td>Strain controlled 
			direct shear apparatus</td>
			<td>Beijing Aerospace Huayu Test Instrument CO.,LTD</td>
			<td>ZJ-4A</td>
			<td>Tensile strength, cohesion, internal friction 
			angle measurement</td>
		</tr>
		<tr>
			<td>Vaccum pump</td>
			<td>Fujiwara,Japan</td>
			<td>750D</td>
			<td>Used to vaccumize the vessel</td>
		</tr>
		<tr>
			<td>Valve</td>
			<td>Jiangsu Subei Valve Co.,Ltd</td>
			<td>S4 NS-MG16-MF1</td>
			<td>Gas seal</td>
		</tr>
		<tr>
			<td>Visual loading vessel</td>
			<td>Huainan Qingda Machinery CO.,Ltd</td>
			<td></td>
			<td>Instrument for sample 
			loading and real-time monitoring</td>
		</tr>
	</tbody>
</table>

a uniaxial compression experiment with co2-bearing coal using a visualized and constant-volume gas-solid coupling test system

Injecting carbon dioxide (CO2) into a deep coal seam is of great significance for reducing the concentration of greenhouse gases in the atmosphere and increasing the recovery of coalbed methane. A visualized and constant-volume gas-solid coupling system is introduced here to investigate the influence of CO2 sorption on the physical and mechanical properties of coal. Being able to keep a constant volume and monitor the sample using a camera, this system offers the potential to improve instrument accuracy and analyze fracture evolution with a fractal geometry method. This paper provides all steps to perform a uniaxial compression experiment with a briquette sample in different CO2 pressures with the gas-solid coupling test system. A briquette, cold-pressed by raw coal and sodium humate cement, is loaded in high-pressure CO2, and its surface is monitored in real-time using a camera. However, the similarity between the briquette and the raw coal still needs improvement, and a flammable gas such as methane (CH4) cannot be injected for the test. The results show that CO2 sorption leads to peak strength and elastic modulus reduction of the briquette, and the fracture evolution of the briquette in a failure state indicates fractal characteristics. The strength, elastic modulus, and fractal dimension are all correlated with CO2 pressure but not with a linear correlation. The visualized and constant-volume gas-solid coupling test system can serve as a platform for experimental research about rock mechanics considering the multifield coupling effect.

The average mass of the briquette sample was 230 g. Depending on the industrial analysis, the briquette exhibited a moisture content of 4.52% and an ash content of 15.52%. Furthermore, the volatile content was approximately 31.24%. As the sodium humate was extracted from the coal, the components of the briquette were similar to raw coal. The physical characteristics are displayed in Table 2.
The comparison of th...

Watch this Scientific Journal Video about A Uniaxial Compression Experiment with CO2-Bearing Coal Using a Visualized and Constant-Volume Gas-Solid Coupling Test System at JoVE.com

A Uniaxial Compression Experiment with CO2-Bearing Coal Using a Visualized and Constant-Volume Gas-Solid Coupling Test System

This protocol demonstrates how to prepare a briquette sample and conduct a uniaxial compression experiment with a briquette in different CO2 pressures using a visualized and constant-volume gas-solid coupling test system. It also aims to investigate changes in terms of coal&#8217;s physical and mechanical properties induced by CO2 adsorption.

A Uniaxial Compression Experiment with CO2-Bearing Coal Using a Visualized and Constant-Volume Gas-Solid Coupling Test System

Injecting carbon dioxide (CO2) into a deep coal seam is of great significance for reducing the concentration of greenhouse gases in the atmosphere and ...

This method can help answer key questions in field of carbon dioxide geological sequestration and coalbed methane recovery about the relationship between coal's properties and gas adsorption. The main advantage of this technique is that static and dynamic load can apply on briquette in constant volume state and whole experiment process is visualized by photographic monitoring. There is no particular requirement for the species of the sample, therefore this method can apply to mechanical tests of any porous rock.To begin, weigh 1000 grams and 300 grams of pulverized coal with a particle size distribution of zero to one millimeter and one to three millimeters respectively. Put them together in a beaker in a mass proportion of 0.76 to 0.24 and use a six millimeter diameter glass rod to mix them well. To prepare the cement, put four grams of sodium humate powder into a beaker and add approximately 96 millimeters of distilled water.Use a glass rod to stir them and make sure that all sodium humate is well dissolved. Then mix 230 grams of mixed coal powder and 20 grams of sodium humate solution in a beaker. To produce a standard sized briquette coat the inner surface of the shaping tools with lubricating oil.Assemble tool components Bottom plate, main body and ring and fill the hole with 250 grams of mixed material. Put Press piston on top of the mixed material and place all parts under the Piston of an electrohydraulic servo universal testing machine. Launch the software WinWdw to control the electrohydraulic servo universal testing machine.In the software, click on force range to set the maximum force to 50 kilonewtons and click on reset to clear the displacement value. Left-click on the option force loading control. Set the moving ratio to 0.1 kilonewtons per second.Set the target force value at 29.4 kilonewtons and holding time at 900 seconds. Then click on start. After that take out the shaping tools and invert them onto a rubber plate.Use a rubber hammer to disassemble tool components in the order from the bottom to the top. Put the briquette in a 40 degree Celsius incubator for 48 hours. First, fix the back door of the visualized vessel with high strength bolts.Connect the computer, data acquisition box and the embedded gas pressure sensor to the back door. To acquire the gas pressure data in the visualized vessel, launch the software Data Acquisition Sensor. On the software, click on start.Open the valve V1 and close V2, V3 and V4 to vacuum the visualized vessel chamber. After 30 minutes turn off V1 and vacuum pump. Open V2 and the gas tank with helium.Use the manual pressure reducing valve to adjust the outlet pressure of the gas tank. Carefully observe the gas pressure curve displayed on data acquisition sensor 16. When it reaches about two megapascals turn off V2 and the gas tank.Then on the computer, launch the software WinWdw to measure the friction force of the loading piston moving downward in the testing machine. In the software, click on force range to set the maximum force to five kilonewtons and click on reset to clear the displacement value. Left-click on the option displacement loading rate and set the moving ratio to one millimeter per minute.The click on start. Open V4 and discharge helium into the air. Disassemble the back door of the visualized vessel and close V4.Measure the height and diameter of the briquette using a vernier caliper with a precision of 0.02 millimeters.Weigh the mass of the briquette using an electronic scale with a precision of 0.01 grams. Install the chain roller of the circumferential deformation test apparatus around the middle position of the briquette and fix the clamp holder. Connect the sensor with the data acquisition box through the aviation connector in the visualized vessel and place them under the loading piston.To ensure the accuracy of the data acquisition, adjust the chain roller and the top surface of the briquette so that they are parallel to the loading piston. Then launch WinWdw to control the universal testing machine. In the software, left-click on the option displacement loading rate.Set the moving ratio at 10 millimeters per minute. On the remote controller, press the down button for the universal testing machine until the distance left between the piston and the briquette is around one to two millimeters. Then assemble the back door of the visualized vessel.Vacuum the visualized vessel chamber as previously. Next open V3 and the gas tank of carbon dioxide at purity 99.99%Use the manual pressure reducing value to adjust the outlet pressure of the gas tank. Carefully observe the gas pressure curve displayed in data acquisition sensor 16.When it gets close enough to the target value, close V3 and the gas tank. After 24 hours of adsorption time the gas pressure curve remains stable and the briquette has reached its adsorption and desorption dynamic equilibrium state. Place a camera with a tripod beside the window of the visualized vessel and adjust the height and angle to ensure that image of the sample is shown in the center of the camera screen.Start the software SDU Deformation Acquisition v2.0 to monitor the circumferential deformation of the briquette. Click on start. On WinWdw click on new sample and type in the height and diameter of the briquette.Click on sectional area and then click on confirm. Click on force range to set the maximum force to five kilonewtons and click on reset to clear the displacement value. Left-click on the option displacement loading rate and set the moving ratio at one millimeter per minute.Click on start to compress the sample. At the same time press the start button on the camera to begin video recording. When the sample totally fails, click on stop and data save in both WinWdw and SDU Deformation Acquisition v2.0.Then press the start button again on the camera to stop video recording. Open V4 to release carbon dioxide in the vessel chamber and disassemble the back door of the vessel. Disconnect the aviation connectors for the gas pressure sensor and circumferential deformation test apparatus.Left-click on the option displacement loading rate on WinWdw, set the moving ratio at 10 millimeters per minute. Press the up button on the remote controller of the universal testing machine. When the loading piston of the vessel is around two to three millimeters above the briquette take the briquette out and remove it from the chain roller.Dismantle the connection tool between the pistons and use a vacuum cleaner to clean the visualized vessel. In this experiment, the isothermal adsorption test proved similar capacity for methane gas adsorption between raw coal and briquette. The strength of the briquette samples used in the test had some fluctuation, but it was rather slight and had little influence on the analysis of the experimental results.When under different carbon dioxide pressures, ranging from zero to two megapascals, the stress axial strain curves showed obvious compaction, elastic and plastic deformation phases. As the carbon dioxide pressure increased the peak strength of the coal sample decreased, where it showed a nonlinear relationship. The elastic modulus decreased under the carbon dioxide saturated condition and that the relationship between the elastic modulus decreased and the gas pressure was nonlinear as well.The images obtained through the camera events the fracture's evolution on the sample's surface, under different carbon dioxide pressures. The box counting dimension method was adopted to describe the feature of fractures in failure state under different carbon dioxide pressures. The correlation coefficients between the box number and the side length were all more than 0.95.The values of the fractal dimension were proportional to those of carbon dioxide pressure and their trend indicated similarity to that of the degree of damage to the coal body. The most important thing is to have a good understanding of test procedure and some experience in experiments of rock mechanics and operation of high-pressure gas. After its improvement, this technique can provide a way for the study of porous media and gas coupling effect under uniaxial or triaxial loading state.Because high pressure gas tanks are used in this technique, people need to operate carefully during gas filling and releasing.

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Environment

A Bending Test for Determining the Atterberg Plastic Limit in Soils

The thread rolling test is the most commonly used method to determine the plastic limit (PL) in soils. It has been widely criticized, because a considerable subjective judgment from the operator that carries out the test is involved during its performance, which may affect the final result significantly. Different alternative methods have been put forward, but they cannot compete with the standard rolling test in speed, simplicity and cost.
In an earlier study by the authors, a simple method with a simple device to determine the PL was presented (the &#34;thread bending test&#34; or simply &#34;bending test&#34;); this method allowed the PL to be obtained with minimal operator interference. In the present paper a version of the original bending test is shown. The experimental basis is the same as the original bending test: soil threads which are 3 mm in diameter and 52 mm long are bent until they start to crack, so that both the bending produced and its related moisture content are determined. However, this new version enables the calculation of PL from an equation, so it is not necessary to plot any curve or straight line to obtain this parameter and, in fact, the PL can be achieved with only one experimental point (but two experimental points are recommended).
The PL results obtained with this new version are very similar to those obtained through the original bending test and the standard rolling test by a highly experienced operator. Only in particular cases of high plasticity cohesive soils, there is a greater difference in the result. Despite this, the bending test works very well for all types of soil, both cohesive and very low plasticity soils, where the latter are the most difficult to test via the standard thread rolling method.

The traditional standardized test for determining the plastic limit in soils is performed by hand, and the result varies depending on the operator. An alternative method based on bending measurements is presented in this study. This allows the plastic limit to be obtained with a clear and objective criterion.

The thread rolling test is the most commonly used method to determine the plastic limit (PL) in soils. It has been widely criticized, because a ...

Measuring and Mapping Patterns of Soil Erosion and Deposition Related to Soil Carbonate Concentrations Under Agricultural Management

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonate (CaCO3) profiles. The objective is to describe a simple conceptual model and detailed protocol for repeatable field and laboratory measurements of these quantities. Here, accurate elevation is measured using a ground-based differential global positioning system (GPS); other data acquisition methods could be applied to the same basic method. Soil samples are collected from prescribed depth intervals and analyzed in the lab using an efficient and precise modified pressure-calcimeter method for quantitative analysis of inorganic carbon concentration. Standard statistical methods are applied to point data, and representative results show significant correlations between changes in soil surface layer CaCO3 and changes in elevation consistent with the conceptual model; CaCO3 generally decreased in depositional areas and increased in erosional areas. Maps are derived from point measurements of elevation and soil CaCO3 to aid analyses. A map of erosional and depositional patterns at the study site, a rain-fed winter wheat field cropped in alternating wheat-fallow strips, shows the interacting effects of water and wind erosion affected by management and topography. Alternative sampling methods and depth intervals are discussed and recommended for future work relating soil erosion and deposition to soil CaCO3.

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonates. Repeatable methods for field and laboratory measurements of these quantities and data analysis methods are described here.

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes ...

Techniques for Investigating the Anatomy of the Ant Visual System

This article outlines a suite of techniques in light microscopy (LM) and electron microscopy (EM) which can be used to study the internal and external eye anatomy of insects. These include traditional histological techniques optimized for work on ant eyes and adapted to work in concert with other techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM). These techniques, although vastly useful, can be difficult for the novice microscopist, so great emphasis has been placed in this article on troubleshooting and optimization for different specimens. We provide information on imaging techniques for the entire specimen (photo-microscopy and SEM) and discuss their advantages and disadvantages. We highlight the technique used in determining lens diameters for the entire eye and discuss new techniques for improvement. Lastly, we discuss techniques involved in preparing samples for LM and TEM, sectioning, staining, and imaging these samples. We discuss the hurdles that one might come across when preparing samples and how best to navigate around them.

This article outlines a suite of techniques in light and electron microscopy to study the internal and external eye anatomy of insects. These include several traditional techniques optimized for work on ant eyes, detailed troubleshooting, and suggestions for optimization for different specimens and regions of interest.

This article outlines a suite of techniques in light microscopy (LM) and electron microscopy (EM) which can be used to study the internal and external eye ...

High-pressure, High-temperature Deformation Experiment Using the New Generation Griggs-type Apparatus

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature (&#62; 300 &#176;C). However, because of the low stress resolution of current solid-pressure-medium apparatuses, high-resolution measurements are today restricted to low-pressure deformation experiments in the gas-pressure-medium apparatus. A new generation of solid-medium piston-cylinder (&#34;Griggs-type&#34;) apparatus is here described. Able to perform high-pressure deformation experiments up to 5 GPa and designed to adapt an internal load cell, such a new apparatus offers the potential to establish a technological basis for high-pressure rheology. This paper provides video-based detailed documentation of the procedure (using the &#34;conventional&#34; solid-salt assembly) to perform high-pressure, high-temperature experiments with the newly designed Griggs-type apparatus. A representative result of a Carrara marble sample deformed at 700 &#176;C, 1.5 GPa and 10-5 s-1 with the new press is also given. The related stress-time curve illustrates all steps of a Griggs-type experiment, from increasing pressure and temperature to sample quenching when deformation is stopped. Together with future developments, the critical steps and limitations of the Griggs apparatus are then discussed.

Rock deformation needs to be quantified at high pressure. A description of the procedure to perform deformation experiments in a newly designed solid-medium Griggs-type apparatus is here given. This provides technological basis for future rheological studies at pressures up to 5 GPa.

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (&#62; 0.5 GPa) and high temperature ...

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.

Rapid and accurate detection of plant pathogens on-site, especially soil-borne pathogens, is crucial to prevent further inoculum production and proliferation of plant diseases in the field. The method developed here using a portable real-time PCR detection system enables on-site diagnosis under field conditions.

On-site diagnosis of plant diseases can be a useful tool for growers for timely decisions enabling the earlier implementation of disease management ...

Stress Distribution During Cold Compression of Rocks and Mineral Aggregates Using Synchrotron-based X-Ray Diffraction

We report detailed procedures for performing compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus (D-DIA) coupled with synchrotron X-radiation. A cube-shaped sample assembly is prepared and compressed, at room temperature, by a set of four X-ray transparent sintered diamond anvils and two tungsten carbide anvils, in the lateral and the vertical planes, respectively. All six anvils are housed within a 250-ton hydraulic press and driven inward simultaneously by two wedged guide blocks. A horizontal energy dispersive X-ray beam is projected through and diffracted by the sample assembly. The beam is commonly in the mode of either white or monochromatic X-ray. In the case of white X-ray, the diffracted X-rays are detected by a solid-state detector array that collects the resulting energy dispersive diffraction pattern. In the case of monochromatic X-ray, the diffracted pattern is recorded using a two-dimensional (2-D) detector, such as an imaging plate or a charge-coupled device (CCD) detector. The 2-D diffraction patterns are analyzed to derive lattice spacings. The elastic strains of the sample are derived from the atomic lattice spacing within grains. The stress is then calculated using the predetermined elastic modulus and the elastic strain. Furthermore, the stress distribution in two-dimensions allow for understanding how stress is distributed in different orientations. In addition, a scintillator in the X-ray path yields a visible light image of the sample environment, which allows for the precise measurement of sample length changes during the experiment, yielding a direct measurement of volume strain on the sample. This type of experiment can quantify the stress distribution within geomaterials, which can ultimately shed light on the mechanism responsible for compaction. Such knowledge has the potential to significantly improve our understanding of key processes in rock mechanics, geotechnical engineering, mineral physics, and material science applications where compactive processes are important.

We report detailed procedures for compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus coupled with synchrotron X-radiation. Such experiments allow quantification of the stress distribution within samples, that ultimately sheds light on compaction processes in geomaterials.

We report detailed procedures for performing compression experiments on rocks and mineral aggregates within a multi-anvil deformation apparatus (D-DIA) ...

Sampling, Sorting, and Characterizing Microplastics in Aquatic Environments with High Suspended Sediment Loads and Large Floating Debris

The ubiquitous presence of plastic debris in the ocean is widely recognized by the public, scientific communities, and government agencies. However, only recently have microplastics in freshwater systems, such as rivers and lakes, been quantified. Microplastic sampling at the surface usually consists of deploying drift nets behind either a stationary or moving boat, which limits the sampling to environments with low levels of suspended sediments and floating or submerged debris. Previous studies that employed drift nets to collect microplastic debris typically used nets with &#8805;300 &#181;m mesh size, allowing plastic debris (particles and fibers) below this size to pass through the net and elude quantification. The protocol detailed here enables: 1) sample collection in environments with high suspended loads and floating or submerged debris and 2) the capture and quantification of microplastic particles and fibers &lt;300 &#181;m. Water samples were collected using a peristaltic pump in low-density polyethylene (PE) containers to be stored before filtering and analysis in the lab. Filtration was done with a custom-made microplastic filtration device containing detachable union joints that housed nylon mesh sieves and mixed cellulose ester membrane filters. Mesh sieves and membrane filters were examined with a stereomicroscope to quantify and separate microplastic particulates and fibers. These materials were then examined using a micro-attenuated total reflectance Fourier transform infrared spectrometer (micro ATR-FTIR) to determine microplastic polymer type. Recovery was measured by spiking samples using blue PE particulates and green nylon fibers; percent recovery was determined to be 100% for particulates and 92% for fibers. This protocol will guide similar studies on microplastics in high velocity rivers with high concentrations of sediment. With simple modifications to the peristaltic pump and filtration device, users can collect and analyze various sample volumes and particulate sizes.

Most microplastic research to date has occurred in marine systems where suspended solid levels are relatively low. Focus is now shifting to freshwater systems, which may feature high sediment loads and floating debris. This protocol addresses collecting and analyzing microplastic samples from aquatic environments that contain high suspended solid loads.

The ubiquitous presence of plastic debris in the ocean is widely recognized by the public, scientific communities, and government agencies. However, only ...

Measuring Stolons and Rhizomes of Turfgrasses Using a Digital Image Analysis System

Length and diameter of stolons or rhizomes are usually measured using simple rulers and calipers. This procedure is slow and laborious, so it is often used on a limited number of stolons or rhizomes. For this reason, these traits are limited in their use for morphological characterization of plants. The use of digital image analysis software technology may overcome measurement errors due to human mistakes, which tend to increase as the number and size of samples also increase. The protocol can be used for any kind of crop but is particularly suitable for forage or grasses, where plants are small and numerous. Turf samples consist of aboveground biomass and an upper soil layer to the depth of maximum rhizome development, depending on the species of interest. In studies, samples are washed from the soil, and stolons/rhizomes are cleaned by hand before analysis by digital image analysis software. The samples are further dried in a laboratory heating oven to measure dry weight; therefore, for each sample, the resultant data are total length, total dry weight, and average diameter. Scanned images can be corrected before analysis by excluding visible extraneous parts, such as remaining roots or leaves not removed with the cleaning process. Indeed, these fragments normally have much smaller diameters than stolons or rhizomes, so they can be easily excluded from analysis by fixing the minimum diameter below which objects are not considered. Stolon or rhizome density per unit area can then be calculated based on sample size. The advantage of this method is quick and efficient measurement of the length and average diameter of large sample numbers of stolons or rhizomes.

A software-based image analysis system provides an alternative method to study the morphology of stoloniferous and rhizomatous species. This protocol permits measurement of the length and diameter of stolons and rhizomes and can be applied to samples with a large amount of biomass and to a wide variety of species.

Length and diameter of stolons or rhizomes are usually measured using simple rulers and calipers. This procedure is slow and laborious, so it is often ...

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

Elemental data are commonly used to infer plant quality as a resource to herbivores. However, the ubiquity of carbon in biomolecules, the presence of nitrogen-containing plant defensive compounds, and variation in species-specific correlations between nitrogen and plant protein content all limit the accuracy of these inferences. Additionally, research focused on plant and/or herbivore physiology require a level of accuracy that is not achieved using generalized correlations. The methods presented here offer researchers a clear and rapid protocol for directly measuring plant soluble proteins and digestible carbohydrates, the two plant macronutrients most closely tied to animal physiological performance. The protocols combine well characterized colorimetric assays with optimized plant-specific digestion steps to provide precise and reproducible results. Our analyses of different sweet corn tissues show that these assays have the sensitivity to detect variation in plant soluble protein and digestible carbohydrate content across multiple spatial scales. These include between-plant differences across growing regions and plant species or varieties, as well as within-plant differences in tissue type and even positional differences within the same tissue. Combining soluble protein and digestible carbohydrate content with elemental data also has the potential to provide new opportunities in plant biology to connect plant mineral nutrition with plant physiological processes. These analyses also help generate the soluble protein and digestible carbohydrate data needed to study nutritional ecology, plant-herbivore interactions and food-web dynamics, which will in turn enhance physiology and ecological research.

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.

Elemental data are commonly used to infer plant quality as a resource to herbivores. However, the ubiquity of carbon in biomolecules, the presence of ...

Xylem Water Distribution in Woody Plants Visualized with a Cryo-scanning Electron Microscope

A scanning electron microscope installed cryo-unit (cryo-SEM) allows specimen observation at subzero temperatures and has been used for exploring water distribution in plant tissues in combination with freeze fixation techniques using liquid nitrogen (LN2). For woody species, however, preparations for observing the xylem transverse-cut surface involve some difficulties due to the orientation of wood fibers. Additionally, higher tension in the water column in xylem conduits can occasionally cause artifactual changes in water distribution, especially during sample fixation and collection. In this study, we demonstrate an efficient procedure to observe the water distribution within the xylem of woody plants in situ&#160;by using a cryostat and cryo-SEM. At first, during sample collection, measuring the xylem water potential should determine whether high tension is present in the xylem conduits. When the xylem water potential is low (&#60; ca. &#8722;0.5 MPa), a tension relaxation procedure is needed to facilitate better preservation of the water status in xylem conduits during sample freeze fixation. Next, a watertight collar is attached around the tree stem and filled with LN2&#160;for freeze fixation of the water status of xylem. After harvesting, care should be taken to ensure that the sample is preserved frozen while completing the procedures of sample preparation for observation. A cryostat is employed to clearly expose the xylem transverse-cut surface. In cryo-SEM observations, time adjustment for freeze-etching is required to remove frost dust and accentuate the edge of the cell walls on the viewing surface. Our results demonstrate the applicability of cryo-SEM techniques for the observation of water distribution within xylem at cellular and subcellular levels. The combination of cryo-SEM with non-destructive in situ observation techniques will profoundly improve the exploration of woody plant water flow dynamics.

Observing the water distribution within the xylem provides significant information regarding water flow dynamics in woody plants. In this study, we demonstrate the practical approach to observe xylem water distribution in situ&#160;by using a cryostat and cryo-SEM, which eliminates artifactual changes in the water status during sample preparation.

A scanning electron microscope installed cryo-unit (cryo-SEM) allows specimen observation at subzero temperatures and has been used for exploring water ...