Name: removal of arsenic using a cationic polymer gel impregnated with iron hydroxide
Uploaded: 2019-06-28T14:00:00
Description: Watch this Scientific Journal Video about Removal of Arsenic Using a Cationic Polymer Gel Impregnated with Iron Hydroxide at JoVE.com

This research was supported by the JSPS KAKENHI Grant Number (26420764, JP17K06892). The contribution of Ministry of Land, Insfrastructure, Transport and Tourism (MLIT), Government of Japan under &#8216;Construction Technology Research and Development Subsidy Program&#8217; to this research is also recognized. &#160;We also acknowledge the contribution of Mr. Kiyotaka Senmoto to this research. Ms. Adele Pitkeathly, Senior Writing Advisor Fellow from Writing Center of Hiroshima University is also acknowledged for English corrections and suggestions. This research was selected for oral presentation in 7th IWA-Aspire Conference, 2017 and Water and Environment Technology Conference, 2018.

CAUTION: Arsenic is extremely toxic. Please use gloves, long sleeve clothing, and experimental goggles at all times during the experiment to prevent any contact of arsenic solution with the skin and eyes. If arsenic comes into contact with any part of your body, wash it immediately with soap. Additionally, please clean up the experimental surroundings regularly so that you and others do not come into contact with arsenic, even when the experiment is not being performed. The symptoms of arsenic exposure may appear after a...

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The main advancement of our developed method is the unique design strategy of the gel composite. The purpose of our gel preparation method was to maximize the amount of iron content in the gel. During the preparation, we added FeCl3 and NaOH to the &#8220;initiator solution&#8221; and the &#8220;monomer solution,&#8221; respectively. Once the monomer solution was mixed with the initiator solution, there was a reaction between FeCl3 and NaOH, producing FeOOH inside the gel. This phenomenon ensured ma...

Water pollution is a great environmental concern, motivating researchers to develop methods for removing contaminants such as arsenic from wastewaster1. Among all the reported methods, adsorption processes are a relatively low cost approach for heavy metal removal2,3,4,5,6,7. Iron oxyhydroxide powders are considered to be one of the most efficient adsorbents for extracting arsenic from aqueous solutions8,9. Still, these materials suffer from a number of drawbacks, including early saturation times and toxic synthetic precursors. Additionally, there is a severe adverse effect in the water quality when these adsorbents are used for a long period of time10. An additional separation process, such as sedimentation or filtration, is then needed to purify the contaminated water, which increases the cost of the production further8,11.
Recently, researchers have developed polymer gels such as cationic hydrogels, microgels, and cryogels that have demonstrated efficient adsorption properties. For example, an arsenic removal rate of 96% was achieved by the cationic cryogel, poly(3-acrylamidopropyl) trimethyl ammonium chloride [p(APTMACl)]12. Additionally, at pH 9, approximately 99.7% removal efficiency was achieved by this cationic hydrogel13. At pH 4, 98.72 mg/g of maximum arsenic adsorption capacity was achieved by the microgel, based on tris(2-aminoethyl) amine (TAEA) and glyceroldiglycidyl ether (GDE), p(TAEA-co-GDE)14. Although these gels demonstrated good adsorption performances, they failed to effectively remove arsenic from water at neutral pH levels, and their selectivities in all studied environments were not reported15. A maximum adsorption capacity of 227 &#956;g/g of was measured when Fe(III)-Sn(IV) mixed binary oxide-coated sand was used at a temperature of 313 K and a pH of 716. Alternatively, Fe-Zr binary oxide-coated sand (IZBOCS) has also been used to remove arsenic and achieved a maximum adsorption capacity of 84.75 mg/g at 318 K and a pH of 717. Other reported adsorbents suffer from low adsorption performances, lack of recyclability, low stability, high operational and maintenance costs, and the use of hazardous chemicals in the synthesis process4.
We sought to address the above limitations by developing a material with improved arsenic adsorption performance, high selectivity in complex environments, recycling capability, and efficient activity at neutral pH levels. Therefore, we developed a cationic gel composite of N,N-dimethylamino propylacrylamide methyl chloride quaternary (DMAPAAQ) gel and iron(III) hydroxide (FeOOH) particles as an adsorbent for arsenic removal. We chose to combine FeOOH with our gel because FeOOH increases the adsorption of both forms of arsenic18. In this study, our gel composite was designed to be non-porous and was impregnated with FeOOH during preparation. In the next section, the details of the gel preparation method, including our strategy for maximizing the content of FeOOH is discussed further.

<table>
	<tbody>
		<tr>
			<td>N,N&#8217;-dimethylamino propylacrylamide, methyl chloride quaternary (DMAPAAQ) (75% in H2O)</td>
			<td>KJ Chemicals Corporation, Japan</td>
			<td>150707</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N&#8217;-Methylene bisacrylamide (MBAA)</td>
			<td>Sigma-Aldrich, USA</td>
			<td>1002040622</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium sulfite (Na2SO3)</td>
			<td>Nacalai Tesque, Inc., Japan</td>
			<td>31922-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium sulfate (Na2SO4)</td>
			<td>Nacalai Tesque, Inc., Japan</td>
			<td>31916-15</td>
			<td></td>
		</tr>
		<tr>
			<td>Di-sodium hydrogenarsenate heptahydrate(Na2HAsO4.7H20)</td>
			<td>Nacalai Tesque, Inc., Japan</td>
			<td>10048-95-0</td>
			<td></td>
		</tr>
		<tr>
			<td>Ferric chloride(FeCl3)</td>
			<td>Nacalai Tesque, Inc., Japan</td>
			<td>19432-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide(NaOH)</td>
			<td>Kishida Chemicals Corporation, Japan</td>
			<td>000-75165</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium peroxodisulfate (APS)</td>
			<td>Kanto Chemical Co. Inc., Japan</td>
			<td>907W2052</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric acid (HCl)</td>
			<td>Kanto Chemical Co. Inc., Japan</td>
			<td>18078-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride (NaCl)</td>
			<td>Nacalai Tesque, Inc., Japan</td>
			<td>31320-05</td>
			<td></td>
		</tr>
	</tbody>
</table>

removal of arsenic using a cationic polymer gel impregnated with iron hydroxide

In this work, we prepared an adsorbent composed of a cationic polymer gel containing iron hydroxide in its structure designed to adsorb arsenic from groundwater. The gel we selected was the N,N-dimethylamino propylacrylamide methyl chloride quaternary (DMAPAAQ) gel. The objective of our preparation method was to ensure the maximum content of iron hydroxide in the structure of the gel. This design approach enabled simultaneous adsorption by both the polymer structure of the gel and the iron hydroxide component, thus, enhancing the adsorption capacity of the material. To examine the performance of the gel, we measured reaction kinetics, carried out pH sensitivity and selectivity analyses, monitored arsenic adsorption performance, and conducted regeneration experiments. We determined that the gel undergoes a chemisorption process and reaches equilibrium at 10 h. Moreover, the gel adsorbed arsenic effectively at neutral pH levels and selectively in complex ion environments, achieving a maximum adsorption volume of 1.63 mM/g. The gel could be regenerated with 87.6% efficiency and NaCl could be used for desorption instead of harmful NaOH. Taken together, the presented gel-based design method is an effective approach for constructing high-performance arsenic adsorbents.

Figure 1 describes the experimental setup for the preparation of the DMAPAAQ+FeOOH gel. Table 1 illustrates the compositions of the materials involved in the preparation of the gel.
Figure 2 shows the relation of contact time with the adsorption of arsenic by the DMAPAAQ+FeOOH gel. In the figure, the amount of adsorption of arsenic was examined at 0.5, ...

Watch this Scientific Journal Video about Removal of Arsenic Using a Cationic Polymer Gel Impregnated with Iron Hydroxide at JoVE.com

Removal of Arsenic Using a Cationic Polymer Gel Impregnated with Iron Hydroxide

In this work, we prepared an adsorbent composed of the cationic N,N-dimethylamino propylacrylamide methyl chloride quaternary (DMAPAAQ) polymer gel and iron hydroxide for adsorbing arsenic from groundwater. The gel was prepared via a novel method designed to ensure the maximum content of iron particles in its structure.

In this work, we prepared an adsorbent composed of a cationic polymer gel containing iron hydroxide in its structure designed to adsorb arsenic from ...

The main advantages of this procedure are that the gel selectively adsorbs arsenic from groundwater at higher arsenic concentrations than the other techniques and the gel can be regenerated. Demonstration of this method is critical because the preparation of the gel and the absorption experiments need to be visualized to replicate the experiments. Arsenic is found in the groundwater of more than 20 countries.The implication of this technique can be extended toward the challenge of removing arsenic from contaminated water. This method can also be applied to the treatment of industrial effluent contaminated with arsenic. When trying this technique for the first time, follow the precautions strictly at all times.The formation of the gel block may be challenging if the solutions are not mixed properly and proportionately. Dry two 20 milliliter measuring flasks and two 20 milliliter beakers equipped with magnetic stir bars. Transfer 4.13 grams of DMAPAAQ, 0.31 grams of N, N'prime methylenebisacrylamide, 0.5 grams of sodium sulfite, and 3.36 grams of sodium hydroxide to one 20 milliliter beaker.Dissolve the solution wholly in distilled water as solvent, stirring it for 30 minutes with the magnetic stir bar. Transfer the mixture from the beaker to one 20 milliliter measuring flask, and add distilled water to generate a 20 milliliter solution. Label the solution as the monomer solution.Similarly, take 0.54 grams of ammonium peroxodisulfate and 7.57 grams of iron chloride in another 20 milliliter beaker. Dissolve the solution completely in distilled water, stirring it for 30 minutes with a magnetic stir bar. Transfer the mixture from the beaker to another 20 milliliter measuring flask.And add distilled water to compose a 20 milliliter solution. Label the solution as the initiator solution. After preparing the experimental setup as diagrammed in the text protocol, transfer the solutions into the respective 20 milliliter separating funnels.Purge the solutions with nitrogen gas for 30 minutes. Mix the solutions together, and stir them in a 50 milliliter test tube with an electric stirrer. Then, place the mixture into a chiller maintained at 10 degrees Celsius for four hours.Take out the gel block from the test tube and place it on a flat cutting board. Get the gel block into a cubic shape five millimeters in length. Soak the gel slices with deionized water for 24 hours to remove the impurities.The next day, spread the gel slices onto a Petri dish and dry them at room temperature for 24 hours. Place the Petri dish with the gel slices in the oven at 50 degrees Celsius for 24 hours. Dry five 40 milliliter plastic containers.Then, measure and place 20 milligrams of dried gel in each 40 milliliter plastic container. Add 40 milliliters of disodium hydrogen arsenate heptahydrate solution to each container at a different concentration. Keep the containers in the stirrer at 20 degrees Celsius and 120 RPM for 24 hours.Collect a five milliliter sample from each container and place in a plastic tube using a micro pipette. Measure the equilibrium arsenic levels in the solutions using high performance liquid chromatography, or HPLC. Use a four by 200 millimeter analytical column, a four by 50 millimeter guard column, and a four millimeter suppressor.For adsorption analysis, add 20 milligrams of dried gel to a dried 40 milliliter plastic container. Then, add 40 milliliters of a 0.2 millimolar disodium hydrogen arsenate heptahydrate solution to the container. Keep the container in the stirrer at 20 degrees Celsius and 120 RPM for 24 hours.Then, collect a five milliliter sample in a plastic tube using a micro pipette. Evaluate the equilibrium arsenic level in the solution using HPLC as before. To clean the gel, first obtain a mesh sieve.Carefully collect the fragile gel pieces, one at a time so that they do not break, and place them in the mesh sieve. Wash the gel for a minimum of five times, using deionized water, so that any remaining arsenic on the surface of the gel is washed away. For desorption analyses, carefully transfer the fragile gel pieces into a dried 40 milliliter plastic container.Add 40 milliliters of a 0.5 molar sodium chloride solution to the container. Keep the container in the stirrer at 20 degrees Celsius and 120 RPM for 24 hours. Collect a five milliliter sample in a plastic tube using a micro pipette, and evaluate the equilibrium arsenic level in the solution using HPLC as before.Repeat the process for eight complete cycles, with each cycle including two rounds of the absorption and desorption analyses steps, separated by gel cleaning steps. The arsenic absorption amount by the cationic polymer gel containing iron hydroxide was plotted at different concentrations of arsenic. The results show that the maximum arsenic adsorption capacity of the gel was 1.36 millimoles per gram.The data are fit with the Langmuir isotherm model. The selective adsorption of arsenic was examined with coexisting sulfate anion. The results show that even if sulfate anion was present in the solution of gel, DMAPAAQ plus iron oxide adsorbed arsenic selectively because of the iron oxide components in the gel structure.The re-usability of the gel was examined for eight continuous days using arsenic solutions for adsorption and sodium chloride for desorption processes. A regeneration efficiency of 87.6%was calculated from the regeneration efficiency from the adsorption data on day one and day seven. Arsenic is extremely hazardous.Please use gloves, long-sleeved clothing, and experimental goggles at all times during the experiment to prevent any contact of arsenic solution with the skin and eyes.

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Environment

Automated Gel Size Selection to Improve the Quality of Next-generation Sequencing Libraries Prepared from Environmental Water Samples

Next-generation sequencing of environmental samples can be challenging because of the variable DNA quantity and quality in these samples. High quality DNA libraries are needed for optimal results from next-generation sequencing. Environmental samples such as water may have low quality and quantities of DNA as well as contaminants that co-precipitate with DNA. The mechanical and enzymatic processes involved in extraction and library preparation may further damage the DNA. Gel size selection enables purification and recovery of DNA fragments of a defined size for sequencing applications. Nevertheless, this task is one of the most time-consuming steps in the DNA library preparation workflow. The protocol described here enables complete automation of agarose gel loading, electrophoretic analysis, and recovery of targeted DNA fragments. 
In this study, we describe a high-throughput approach to prepare high quality DNA libraries from freshwater samples that can be applied also to other environmental samples. We used an indirect approach to concentrate bacterial cells from environmental freshwater samples; DNA was extracted using a commercially available DNA extraction kit, and DNA libraries were prepared using a commercial transposon-based protocol. DNA fragments of 500 to 800 bp were gel size selected using Ranger Technology, an automated electrophoresis workstation. Sequencing of the size-selected DNA libraries demonstrated significant improvements to read length and quality of the sequencing reads.

This manuscript describes an automated gel size selection approach for purifying DNA fragments for next-generation sequencing. The Ranger Technology provides complete automation of the entire process of agarose gel loading, electrophoretic analysis, and recovery of targeted DNA fragments allowing for high-throughput and high quality next-generation sequencing libraries.

Next-generation sequencing of environmental samples can be challenging because of the variable DNA quantity and quality in these samples. High quality DNA ...

Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling from hydrothermal sources in the Precambrian ocean was oxidized by molecular oxygen [O2] produced by cyanobacteria. The oldest BIFs, deposited prior to the Great Oxidation Event (GOE) at about 2.4 billion years (Gy) ago, could have formed by direct oxidation of Fe(II) by anoxygenic photoferrotrophs under anoxic conditions. As a method for testing the geochemical and mineralogical patterns that develop under different biological scenarios, we designed a 40 cm long vertical flow-through column to simulate an anoxic Fe(II)-rich marine upwelling system representative of an ancient ocean on a lab scale. The cylinder was packed with a porous glass bead matrix to stabilize the geochemical gradients, and liquid samples for iron quantification could be taken throughout the water column. Dissolved oxygen was detected non-invasively via optodes from the outside. Results from biotic experiments that involved upwelling fluxes of Fe(II) from the bottom, a distinct light gradient from top, and cyanobacteria present in the water column, show clear evidence for the formation of Fe(III) mineral precipitates and development of a chemocline between Fe(II) and O2. This column allows us to test hypotheses for the formation of the BIFs by culturing cyanobacteria (and in the future photoferrotrophs) under simulated marine Precambrian conditions. Furthermore we hypothesize that our column concept allows for the simulation of various chemical and physical environments &#8212; including shallow marine or lacustrine sediments.

Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

We simulated a Precambrian ferruginous marine upwelling system in a lab-scale vertical flow-through column. The goal was to understand how geochemical profiles of O2 and Fe(II) evolve as cyanobacteria produce O2. The results show the establishment of a chemocline due to Fe(II) oxidation by photosynthetically produced O2.

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling ...

Biofilm Removal Using Carbon Dioxide Aerosols without Nitrogen Purge

Biofilms can cause serious concerns in many applications. Not only can they cause economic losses, but they can also present a public health hazard. Therefore, it is highly desirable to remove biofilms from surfaces. Many studies on CO2 aerosol cleaning have employed nitrogen purges to increase biofilm removal efficiency by reducing the moisture condensation generated during the cleaning. However, in this study, periodic jets of CO2 aerosols without nitrogen purges were used to remove Pseudomonas putida biofilms from polished stainless steel surfaces. CO2 aerosols are mixtures of solid and gaseous CO2 and are generated when high-pressure CO2 gas is adiabatically expanded through a nozzle. These high-speed aerosols were applied to a biofilm that had been grown for 24 hr. The removal efficiency ranged from 90.36% to 98.29% and was evaluated by measuring the fluorescence intensity of the biofilm as the treatment time was varied from 16 sec to 88 sec. We also performed experiments to compare the removal efficiencies with and without nitrogen purges; the measured biofilm removal efficiencies were not significantly different from each other (t-test, p &gt; 0.55). Therefore, this technique can be used to clean various bio-contaminated surfaces within one minute.

Biofilms on surfaces can be effectively and rapidly removed by using a periodic jet of carbon dioxide aerosols without a nitrogen purge.

Biofilms can cause serious concerns in many applications. Not only can they cause economic losses, but they can also present a public health hazard. ...

Protocol for Microplastics Sampling on the Sea Surface and Sample Analysis

Microplastic pollution in the marine environment is a scientific topic that has received increasing attention over the last decade. The majority of scientific publications address microplastic pollution of the sea surface. The protocol below describes the methodology for sampling, sample preparation, separation and chemical identification of microplastic particles. A manta net fixed on an &#187;A frame&#171; attached to the side of the vessel was used for sampling. Microplastic particles caught in the cod end of the net were separated from samples by visual identification and use of stereomicroscopes. Particles were analyzed for their size using an image analysis program and for their chemical structure using ATR-FTIR and micro FTIR spectroscopy. The described protocol is in line with recommendations for microplastics monitoring published by the Marine Strategy Framework Directive (MSFD) Technical Subgroup on Marine Litter. This written protocol with video guide will support the work of researchers that deal with microplastics monitoring all over the world.

The protocol below describes the methodology for: microplastics sampling on the sea surface, separation of microplastic and chemical identification of particles. This protocol is in line with the recommendations for microplastics monitoring published by the MSFD Technical Subgroup on Marine Litter.

Microplastic pollution in the marine environment is a scientific topic that has received increasing attention over the last decade. The majority of ...

Determination of Inorganic Arsenic in a Wide Range of Food Matrices using Hydride Generation - Atomic Absorption Spectrometry.

The European Food Safety Authority (EFSA) underlined in its Scientific Opinion on Arsenic in Food that in order to support a sound exposure assessment to inorganic arsenic through diet, information about distribution of arsenic species in various food types must be generated. A method, previously validated in a collaborative trial, has been applied to determine inorganic arsenic in a wide variety of food matrices, covering grains, mushrooms and food of marine origin (31 samples in total). The method is based on detection by flow injection-hydride generation-atomic absorption spectrometry of the iAs selectively extracted into chloroform after digestion of the proteins with concentrated HCl. The method is characterized by a limit of quantification of 10 &#181;g/kg dry weight, which allowed quantification of inorganic arsenic in a large amount of food matrices. Information is provided about performance scores given to results obtained with this method and which were reported by different laboratories in several proficiency tests. The percentage of satisfactory results obtained with the discussed method is higher than that of the results obtained with other analytical approaches.

The usefulness of an analytical method to determine inorganic arsenic in a wide range of food matrices is demonstrated. The method consists of selective extraction of inorganic arsenic into chloroform with a final determination by hydride generation-atomic absorption spectrometry.

The European Food Safety Authority (EFSA) underlined in its Scientific Opinion on Arsenic in Food that in order to support a sound exposure assessment to ...

Optimized Procedure for Determining the Adsorption of Phosphonates onto Granular Ferric Hydroxide using a Miniaturized Phosphorus Determination Method

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric hydroxide (GFH), with little effort and high reliability. The phosphonate, e.g., nitrilotrimethylphosphonic acid (NTMP), is brought into contact with the GFH in a rotator in a solution buffered by an organic acid (e.g., acetic acid) or Good buffer (e.g., 2-(N-morpholino)ethanesulfonic acid) [MES] and N-cyclohexyl-2-hydroxyl-3-aminopropanesulfonic acid [CAPSO]) in a concentration of 10 mM for a specific time in 50 mL centrifuge tubes. Subsequently, after membrane filtration (0.45 &#181;m pore size), the total phosphorus (total P) concentration is measured using a specifically developed determination method (ISOmini). This method is a modification and simplification of the ISO 6878 method: a 4 mL sample is mixed with H2SO4 and K2S2O8 in a screw cap vial, heated to 148-150 &#176;C for 1 h and then mixed with NaOH, ascorbic acid and acidified molybdate with antimony(III) (final volume of 10 mL) to produce a blue complex. The color intensity, which is linearly proportional to the phosphorus concentration, is measured spectrophotometrically (880 nm). It is demonstrated that the buffer concentration used has no significant effect on the adsorption of phosphonate between pH 4 and 12. The buffers, therefore, do not compete with the phosphonate for adsorption sites. Furthermore, the relatively high concentration of the buffer requires a higher dosage concentration of oxidizing agent (K2S2O8) for digestion than that specified in ISO 6878, which, together with the NaOH dosage, is matched to each buffer. Despite the simplification, the ISOmini method does not lose any of its accuracy compared to the standardized method.

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric hydroxide, with little effort and high reliability. In a buffered solution, the phosphonate is brought into contact with the adsorbent using a rotator and then analyzed via a miniaturized phosphorus determination method.

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric ...

Assessing the Particulate Matter Removal Abilities of Tree Leaves

Based on the conventional cleaning methods (water cleaning (WC) + brush cleaning (BC)), this study evaluated the influence of ultrasonic cleaning (UC) on collecting various sized particulate matter (PM) retained on leaf surfaces. We further characterized the retention efficiency of leaves to various sized PM, which will help to assess the abilities of urban trees to remove PM from ambient air quantitatively. 
Taking three broadleaf tree species (Ginkgo biloba, Sophora japonica, and Salix babylonica) and two needleleaf tree species (Pinus tabuliformis and Sabina chinensis) as the research objects, leaf samples were collected 4 days (short PM retention period) and 14 days (long PM retention period) after the latest rainfall. PM retained on the leaf surfaces was collected by means of WC, BC, and UC in sequence. Then, retention efficiencies of leaves (AEleaf) to three types of the various sized PM, including easily removable PM (ERP), difficult-to-remove PM (DRP), and totally removable PM (TRP), were calculated. Only around 23%-45% of the total PM retained on leaves could be cleaned off and collected by WC. When the leaves were cleaned through WC+BC, the underestimation of the PM retention capacity of different tree species was in the range of 29%-46% for various sized PM. Almost all PM retained on leaves could be removed if UC was supplemented to WC+BC. 
In conclusion, if the UC was complemented after the conventional cleaning methods, more PM on leaf surfaces could be eluted and collected. The procedure developed in this study can be used for assessing the PM removal abilities of different tree species.

The ultrasonic cleaning method was applied to elute the particulate matter (PM) retained on leaf surfaces after PM was eluted by the conventional cleaning methods (water cleaning only or water cleaning plus brush cleaning). The methodology can help to improve the estimation accuracy for PM retention capacity of leaves.

Based on the conventional cleaning methods (water cleaning (WC) + brush cleaning (BC)), this study evaluated the influence of ultrasonic cleaning (UC) on ...

Separation of Spinach Thylakoid Protein Complexes by Native Green Gel Electrophoresis and Band Characterization using Time-Correlated Single Photon Counting

The light reactions of photosynthesis are carried out by a series of pigmented protein complexes in the thylakoid membranes. The stoichiometry and organization of these complexes is highly dynamic on both long and short time scales due to processes that adapt photosynthesis to changing environmental conditions (i.e., non-photochemical quenching, state transitions, and the long-term response). Historically, these processes have been described spectroscopically in terms of changes in chlorophyll fluorescence, and spectroscopy remains a vital method for monitoring photosynthetic parameters. There are a limited number of ways in which the underlying protein complex dynamics can be visualized. Here we describe a fast and simple method for the high-resolution separation and visualization of thylakoid complexes, native green gel electrophoresis. This method is coupled with time-correlated single photon counting for detailed characterization of the chlorophyll fluorescence properties of bands separated on the green gel.

Here we present a protocol to separate solubilized thylakoid complexes by Native Green Gel electrophoresis. Green gel bands are subsequently characterized by Time Correlated Single Photon Counting (TCSPC) and basic steps for data analysis are provided.

The light reactions of photosynthesis are carried out by a series of pigmented protein complexes in the thylakoid membranes. The stoichiometry and ...

In Vitro Scratch Assay to Demonstrate Effects of Arsenic on Skin Cell Migration

Understanding the physiologic mechanisms of wound healing has been the focus of ongoing research for many years. This research directly translates into changes in clinical standards used for treating wounds and decreasing morbidity and mortality for patients. Wound healing is a complex process that requires strategic cell and tissue interaction and function. One of the many critically important functions of wound healing is individual and collective cellular migration. Upon injury, various cells from the blood, surrounding connective, and epithelial tissues rapidly migrate to the wound site by way of chemical and/or physical stimuli. This migration response can largely dictate the outcomes and success of a healing wound. Understanding this specific cellular function is important for translational medicine that can lead to improved wound healing outcomes. Here, we describe a protocol used to better understand cellular migration as it pertains to wound healing, and how changes to the cellular environment can significantly alter this process. In this example study, dermal fibroblasts were grown in media supplemented with fetal bovine serum (FBS) as monolayer cultures in tissue culture flasks. Cells were aseptically transferred into tissue culture treated 12-well plates and grown to 100% confluence. Upon reaching confluence, the cells in the monolayer were vertically scratched using a p200 pipet tip. Arsenic diluted in culture media supplemented with FBS was added to individual wells at environmentally relevant doses ranging 0.1-10 &#956;M. Images were captured every 4 hours (h) over a 24 h period using an inverted light microscope to observe cellular migration (wound closure). Images were individually analyzed using image analysis software, and percent wound closure was calculated. Results demonstrate that arsenic slows down wound healing. This technique provides a rapid and inexpensive first screen for evaluation of the effects of contaminants on wound healing.

In Vitro Scratch Assay to Demonstrate Effects of Arsenic on Skin Cell Migration

This study focuses on an in vitro model of wound healing (scratch assay) as a mechanism for determining how environmental contaminants such as arsenic influence cellular migration. The results demonstrate that this in vitro assay provides rapid and early indications of changes to cellular migration prior to in vivo experimentation.

Understanding the physiologic mechanisms of wound healing has been the focus of ongoing research for many years. This research directly translates into ...

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.

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.

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