Name: separation of uranium and thorium for 230th-u dating of submarine hydrothermal sulfides
Uploaded: 2019-05-20T12:30:00
Description: Watch this Scientific Journal Video about Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides at JoVE.com

This study was financially supported by Experimental Technology Innovation Foundation of Institute of Geology and Geophysics, Chinese Academy of Sciences (No. 11890940), and China Ocean Mineral Resources R &#38; D Association Project (No. DY135-S2-2-07).

1. Preparing the sample, reagents, and containers
<ol>
	<li>Clean the fume hood, hotplate and the balance room bench for the chemical experiment with sprayed alcohol or ultrapure water.</li>
	<li>Prepare sub-boiled acids (2 M HCl, 8 M HCl, 7 M HNO3, and 14 M HNO3), clean beakers and any apparatus before sample processed. 
	NOTE: Sulfide samples presented in this study were collected from newly discovered hydrothermal zones in the South Atlantic. Approximately 60 mg of powdered sample was used...

<ol>
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L., Brichet, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Actinide-series+disequilibrium+as+a+tool+to+establish+the+chronology+of+deep-sea+hydrothermal+activity.">Actinide-series disequilibrium as a tool to establish the chronology of deep-sea hydrothermal activity.</a> Geochimica et Cosmochimica Acta. 57 (6), 1221-1231 (1993).</li><li>Lalou, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+age+data+for+Mid-Atlantic+Ridge+hydrothermal+sites:+TAG+and+Snakepit+chronology+revisited.">New age data for Mid-Atlantic Ridge hydrothermal sites: TAG and Snakepit chronology revisited.</a> Journal of Geophysical Research. 98, 9705-9713 (1993).</li><li>Lalou, C., Reyss, J. L., Brichet, E., Rona, P. A., Thompson, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrothermal+activity+on+a+105-year+scale+at+a+slow-spreading+ridge,+TAG+hydrothermal+field,+Mid-Atlantic+Ridge+26&#176;+N.">Hydrothermal activity on a 105-year scale at a slow-spreading ridge, TAG hydrothermal field, Mid-Atlantic Ridge 26&#176; N.</a> Journal of Geophysical Research. 100 (B9), 17855-17862 (1995).</li><li>Kadko, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Radio+isotopic+studies+of+submarine+hydrothermal+vents.">Radio isotopic studies of submarine hydrothermal vents.</a> Reviews of Geophysics. 34 (3), 349-366 (1996).</li><li>Lalou, C., Mu &#776;nch, U., Halbach, P., Reyss, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Radiochronological+investigation+of+hydrothermal+deposits+from+the+MESO+zone,+Central+Indian+Ridge.">Radiochronological investigation of hydrothermal deposits from the MESO zone, Central Indian Ridge.</a> Marine Geology. 149 (149), 243-254 (1998).</li><li>Yejian, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrothermal+Activity+Events+at+Kairei+Field,+Central+Indian+Ridge+25&#176;S.">Hydrothermal Activity Events at Kairei Field, Central Indian Ridge 25&#176;S.</a> Resource Geology. 62 (2), 208-214 (2012).</li><li>Yejian, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mineralogy+and+geochemistry+of+hydrothermal+precipitates+from+Kairei+hydrothermal+field,+Central+Indian+Ridge.">Mineralogy and geochemistry of hydrothermal precipitates from Kairei hydrothermal field, Central Indian Ridge.</a> Marine Geology. 354 (3), 69-80 (2014).</li><li>Jun-ichiro, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dating+of+Hydrothermal+Mineralization+in+Active+Hydrothermal+Fields+in+the+Southern+Mariana+Trough.">Dating of Hydrothermal Mineralization in Active Hydrothermal Fields in the Southern Mariana Trough.</a> Subseafloor Biosphere Linked to Hydrothermal Systems. , 289-300 (2015).</li><li>Takamasa, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=U-Th+radioactive+disequilibrium+and+ESR+dating+of+a+barite-containing+sulfide+crust+from+South+Mariana+Trough.">U-Th radioactive disequilibrium and ESR dating of a barite-containing sulfide crust from South Mariana Trough.</a> Quaternary Geochronology. 15 (1), 38-46 (2013).</li><li>Weifang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=230Th/238U+dating+of+hydrothermal+sulfides+from+Duanqiao+hydrothermal+field,+Southwest+Indian+Ridge.">230Th/238U dating of hydrothermal sulfides from Duanqiao hydrothermal field, Southwest Indian Ridge.</a> Marine Geophysical Research. 38 (1-2), 71-83 (2017).</li><li>Lisheng, W., Zhibang, M., Hai, C., Wuhui, D., Jule, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+230Th+age+of+Uranium-series+standard+samples+by+multiple+collector+inductively+coupled+plasma+mass+spectromerty.">Determination of 230Th age of Uranium-series standard samples by multiple collector inductively coupled plasma mass spectromerty.</a> Journal of China Mass Spectrometry Society. 37 (3), 262-272 (2016).</li><li>Wang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=U+concentration+and+234U/238U+of+seawater+from+the+Okinawa+Trough+and+Indian+Ocean+using+MC-ICPMS+with+SEM+protocols.">U concentration and 234U/238U of seawater from the Okinawa Trough and Indian Ocean using MC-ICPMS with SEM protocols.</a> Marine Chemistry. 196, 71-80 (2017).</li><li>Hai, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improvements+in+230Th+dating,+230Th+and+234U+half-life+values,+and+U-Th+isotopic+measurements+by+multi-collector+inductively+coupled+plasma+mass+spectrometry.">Improvements in 230Th dating, 230Th and 234U half-life values, and U-Th isotopic measurements by multi-collector inductively coupled plasma mass spectrometry.</a> Earth and Planetary Science Letters. , 82-91 (2013).</li><li>Edwards, R. L., Chen, J. H., Ku, T. -. L., Wasserburg, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Precise+timing+of+the+last+interglacial+period+from+mass+spectrometric+analysis+of+230Th+in+corals.">Precise timing of the last interglacial period from mass spectrometric analysis of 230Th in corals.</a> Science. 236 (4808), 1537-1553 (1987).</li><li>Edwards, R. L., Taylor, F. W., Wasserburg, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dating+earthquakes+with+high+precision+thorium-230+ages+of+very+young+corals+[J].">Dating earthquakes with high precision thorium-230 ages of very young corals [J].</a> Earth and Planetary Science Letters. 90 (4), 371-381 (1988).</li><li>Hai, C., Jess, A., Edwards, R. L., Boyle, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=U-Th+dating+of+deep-sea+corals.">U-Th dating of deep-sea corals.</a> Geochimica et Cosmochimica Acta. 64 (14), 2401-2416 (2000).</li><li>Ishibashi, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dating+of+Hydrothermal+Mineralization+in+Active+Hydrothermal+Fields+in+the+Southern+Mariana+Trough.">Dating of Hydrothermal Mineralization in Active Hydrothermal Fields in the Southern Mariana Trough.</a> Subseafloor Biosphere Linked to Hydrothermal Systems. , 289-300 (2015).</li><li>Jaffey, A. H., Flynn, K. F., Glendenin, L. E., Bentley, W. C., Essling, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Precision+measurement+of+half-lives+and+specific+activities+of+235U+and+238U.">Precision measurement of half-lives and specific activities of 235U and 238U.</a> Physical Review C. 4, 1889-1906 (1971).</li><li>Richter, S., Goldberg, S. A., Mason, P. B., Traina, A. J., Schwieters, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Linearity+tests+for+secondary+electron+multipliers+used+in+isotope+ratio+mass+spectrometry.">Linearity tests for secondary electron multipliers used in isotope ratio mass spectrometry.</a> International Journal of Mass Spectrometry. 206 (1-2), 105-127 (2001).</li></ol>

Some critical steps must be followed to ensure success of this protocol. Ensure that all operations are carried out in clean chemistry room under fume hood with clean air circulation. Purify all regents in this process in advance and clean the apparatus before use. Dissolve the samples completely in the process of making the 7 M HNO3 solution which is then loaded onto the 7 M HNO3-conditioned resins. If there is any insoluble substance in the sample, it will be redissolved after drying. Additional i...

Submarine hydrothermal sulfides have been a steady source of metals like iron, copper, zinc and lead. They are also seen as economically viable resources of silver and gold. The location and size of the deposits are a record of the history of hydrothermal venting on the seafloor. Dating of a hydrothermal sulfide can provide important information regarding the formation and alteration mechanism of the sulfide ore deposit, seafloor hydrothermal activity history, and growth rate of large sulfide deposits1,2,3. 238U-234U-230Th disequilibrium dating is an effective isotopic method of age estimation for hydrothermal sulfides4,5,6,7,8,9,10,11,12, where the purification and separation of U and Th isotopes is necessary. This text describes a protocol for U and Th isotopes separation and 230Th-U dating of sulfides sample by MC-ICPMS.
Geological materials which contain U and Th remain undisturbed for several million years, and a state of secular equilibrium between all the nuclides in the radioactive series is established. However, a combination of chemical solubility and nuclear recoil factors often create disequilibrium, in which the members of the decay series are separated from each other through processes such as deposition, transport and weathering. For example, when a sulfide deposit is formed, the state of 238U, 234U and 230Th is of disequilibrium, and the long-lived 238U can decay gradually towards short-lived 234U and 230Th subsequently. Assuming (i) the system remains closed with respect to U and Th isotopes, and (ii) initial amount of 230Th and 232Th incorporated into sulfide samples is zero, it is possible to determine the time of deposition by measuring the present-day activity ratios of 230Th/238U and 234U/238U. However, the initial amount of Th is not zero in the sample, and we assume the initial 230Th/232Th atomic ratio is 4.4 &#177; 2.2 x 10-6. The applicable dating range of this method is approximately ~10-6 x 105 years13,14. However, the large difference between the abundance of uranium and thorium makes measurement challenging. Hence, it is very important to establish a chemical procedure for U-Th dating by MC-ICPMS.
In the past 30 years, most studies focused more measurements of carbonate materials14,15,16,17 and less on sulfide deposits11,12,18,19. Alpha-particle counting methods have traditionally been used for the study of 230Th/238U disequilibrium of submarine hydrothermal sulfides1. However, analytical uncertainty of 5-17% is a limiting factor that affects the precision of age determination of sulfides1,8,9. These techniques generally suffer from the use of relatively large columns and reagent volumes and the need for multiple column passes for purification and separation U-Th from a sample. Recent developments in MC-ICPMS have greatly improved the precision of U-Th isotopic measurements (&#60;5&#8240; for ages)14 and have significantly reduced the sample size (&#60;0.2 g) required for analysis. In these works, many chemical separation procedures have been developed, and have achieved excellent chemical yields with low chemical background12,13.
Here we present a chemical-based protocol to obtain samples that are sufficiently clean for MC-ICPMS analysis. It is suitable for the dating of hydrothermal sulfide samples of age &#60;6 x 105 years14. With this technique, the separated U and Th isotopic fractions can meet measuring requirements by MC-ICPMS. The age of the hydrothermal sulfide sample can be calculated from the extent of disequilibria between 230Th and 234U and between 234U and 238U by using the described activity decay equation.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>AG 1-X8 anion-exchange resin</td>
			<td>BIO-RAD</td>
			<td>140-1441</td>
			<td>Separating rare elements</td>
		</tr>
		<tr>
			<td>Ammonia solution</td>
			<td>Kanto Chemical CO., INC.</td>
			<td>1336-21-6</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Glass vials</td>
			<td>BOTEX</td>
			<td>None</td>
			<td>Sample collection</td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>Sinopharem chemical reagent Co. Ltd</td>
			<td>7647-01-0</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Hydrofluoric acid</td>
			<td>EMD Millipore CO.</td>
			<td>7664-39-5</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Neptune Plus</td>
			<td>Thermo Fisher Scientific CO.</td>
			<td>None</td>
			<td>Apparatus</td>
		</tr>
		<tr>
			<td>Nitric acid</td>
			<td>Sinopharem chemical reagent Co. Ltd</td>
			<td>7697-37-2</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Perchloric acid</td>
			<td>Kanto Chemical CO., INC.</td>
			<td>32059-1B</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Ultrapure water</td>
			<td>Merck Millipore</td>
			<td>None</td>
			<td>Producted by Mill-Q Advantage systerm</td>
		</tr>
		<tr>
			<td>Wipe paper</td>
			<td>Kimberley-Clark</td>
			<td>0123-12</td>
			<td>Wipe and clean</td>
		</tr>
		<tr>
			<td>2 ml vial</td>
			<td>Nelgene</td>
			<td>5000-0020</td>
			<td>Sample collection</td>
		</tr>
		<tr>
			<td>229Th-233U-236U spike</td>
			<td>None</td>
			<td>None</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>7 ml PFA beaker</td>
			<td>Savillex</td>
			<td>200-007-20</td>
			<td>Sample treatment</td>
		</tr>
		<tr>
			<td>10 ml centrifuge</td>
			<td>Nelgene</td>
			<td>3110-1000</td>
			<td>Sample treatment</td>
		</tr>
		<tr>
			<td>30 ml PFA beaker</td>
			<td>Savillex</td>
			<td>200-007-20</td>
			<td>Sample treatment</td>
		</tr>
	</tbody>
</table>

separation of uranium and thorium for 230th-u dating of submarine hydrothermal sulfides

The age of a submarine hydrothermal sulfide is a significant index for estimating the size of hydrothermal ore deposits. Uranium and thorium isotopes in the samples can be separated for 230Th-U dating. This article presents a method to purify and separate U and Th isotopes in submarine hydrothermal sulfide samples. Following this technique, the separated U and Th fractions can meet measuring requirements by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). The age of the hydrothermal sulfide sample can be calculated by measuring the present-day activity ratios of 230Th/238U and 234U/238U. A super clean room is necessary for this experiment. Cleaned regents and supplies are used to reduce the contamination during the sample processes. Balance, hotplate, and centrifuge are also used. The sulfide sample is powdered for analysis and less than 0.2 g sample is used. Briefly, the sample is weighed, dissolved, added to 229Th-233U-236U double spike solution, Fe co-precipitated, and separated on an anion-exchange resin extraction column. Approximately 50 ng U is consumed for 230Th-U dating of sulfides sample by MC-ICPMS.

Using this procure, a submarine hydrothermal sulfide sample can be completely dissolved. Following this protocol, the Th fraction was eluted from the hydrothermal sulfide sample using 8 M HCl. Meanwhile, the U fraction of the hydrothermal sulfide sample was eluted with 0.1 M HNO3. U and Th fractions were dissolved in the 2% HNO3 (+0.1% HF) solution (see Figure 2) and stored in 2 mL capacity vials. The mixture was then analyzed by MC-ICPMS.
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Watch this Scientific Journal Video about Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides at JoVE.com

Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides

The protocol describes a method to purify and separate the U and Th nuclide in submarine hydrothermal sulfide sample with Fe co-precipitation and extraction chromatography for 230Th-U disequilibrium dating.

Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides

The age of a submarine hydrothermal sulfide is a significant index for estimating the size of hydrothermal ore deposits. Uranium and thorium isotopes in ...

This article presents a method to purify and separate uranium and thorium isotopes in submarine hydrothermal sulfide samples. With this technique, uranium and thorium isotopic can be measured by MC-ICPMS, as suitable for dating samples with age less than 600, 000 years and provide important information of sulfide ore deposits, seafloor hydrothermal activity history and growth rates of large sulfide deposits. With this technique, less than 0.2 gram powdered sulfide sample is used and only 50 nanogram uranium is consumed for uranium series dating by MC-ICPMS.Some critical steps must be followed to ensure success of this protocol. Purify all chemical reagents and clean the apparatus. Be sure all operations are carried out under the fume hood and clean air circulation.Avoid the cross-contamination from the adjacent samples during the sample processing and reaching the condition of uranium and the thorium in accordance with your technique. The major imitation of this technique is related to the uranium 238 and the thorium 232. Concentration of the sample, it is best to choose samples where the uranium is more than and the thorium is less than 10 ppb.First, use sprayed alcohol, or ultra pure water, to clean the fume hood, hot plate and the balance room bench for the chemical experiment. In the fume hood, prepare the sub-boiled hydrochloric acid and nitric acid and sulfide samples in vials. Label 30 milliliter PFA bottles twice, to prevent erasure and weigh the blank bottles on a balance accurate to plus or minus 0.0001 grams.Pour the samples into the PFA bottles, cover with a lid and weigh the bottles. Add approximately one liter of ultra-pure water into the bottle, rotate the bottle to rinse the inner wall and shake the bottle carefully to have water cover all the samples. Place the sample containing bottles in the fume hood, open the lid and use a pipette to add three milliliters of 14 molar nitric acid, or aqua regia, into each bottle containing the samples.Place the PFA bottles on the hot plate and set the hot plate temperature to 170 degrees Celsius to dissolve the samples completely. Leave the solution to cool for at least 30 minutes. Then add 100 to 300 milliliters of thorium-229, uranium-233 and uranium-236 spike solution of known activity into each sample solution.Place the bottles on the hot plate at 170 degrees Celsius for five hours to dry. Dissolve each sample in two drops of 14 molar nitric acid and dry them on the hot plate at 170 degrees Celsius again. Prepare clean, 15 milliliter centrifuge tubes, label and place them in a tube stand, add approximately 0.1 milliliters of two molar hydrochloric acid into each bottle containing the dried samples and shake gently to completely dissolve the samples.Transfer each sample into a centrifuge tube. Add several drops of ammonia solution into each tube until the acid is neutralized, showing a reddish-brown uranium and thorium isotope precipitate, biferric oxyhydroxide. Seal the centrifuge tubes, level them and centrifuge at 2340 times g for seven minutes.Discard the supernatant. Add ultra-pure water to the tubes and shake to resuspend. Centrifuge again to wash and repeat the wash two more times.Next, dissolve the precipitate with 1.5 milliliters of seven molar nitric acid. Transfer the solution into the corresponding bottle, add one drop of perchloric acid to remove organic matters and dry each sample on the hot plate at 170 degrees Celsius for about 30 minutes. To prepare an anion exchange column, insert frit into each PTFE column slowly at the bottom, with the help of a PTFE pipe.Put the columns on the holder, pipette cleaned anion exchange resins into the columns. Fill the whole column with ultra-pure water and add one drop of 14 molar nitric acid. Then add two column volumes of seven molar nitric acid twice to remove the trace elements.Dissolve each sample in 0.5 milliliters of 7 molar nitric acid. Load it onto the column carefully, let it drip across the column, into the waste beaker. Next, add two column volumes and one column volume of seven molar nitric acid successively into each column.Iron and other metal elements in the samples are removed, while uranium and thorium are retained by the resin. After that, add two column volumes and one column volume of eight molar hydrochloric acid successively into each column, to elute thorium fraction. Collect the thorium fraction, using a seven milliliter PFA bottle for each column.Add one drop of perchloric acid into the bottle and dry the fraction on a hot plate at 170 degrees Celsius for about 30 minutes. Next, elute uranium fraction from the resin with two column volumes of 0.1 molar nitric acid twice. Collect the eluate in new PFA bottles then add one drop of perchloric acid and dry it on the hot plate at 170 degrees Celsius for about 30 minutes.Now prepare and label two milliliter capacity vials. Dissolve each sample in one drop of 14 molar nitric acid and dry it on the hot plate at 170 degrees Celsius for less than five minutes, until half a drop is left. Transfer them, along with 0.2 milliliters of 2%nitric acid and 0.1%hydrofluoric acid, into the corresponding vials for instrument measurement.Using this procedure, submarine hydrothermal sulfide samples can be completely dissolved for uranium and thorium analysis. In this example, uranium content ranged from 178 to 5, 118.2 nanograms per gram and thorium content ranged from 603 to 7, 212 picograms per gram. Five samples had ages ranging from 567 to 21, 936 years before the year 2000 AD.Sample consumption was about 60 milligrams, except S32 wherein only 17 milligrams of sample was consumed.In these steps, the concentration was acid reagents but we determined actually, to ensure success. Following this procedure, uranium and thorium isotopes reduce out and they still find it also determined the It can provide real chemical information for sulfide deposits. Our reagents are harmful to human body.Please strictly comply with the relevant specifications to ensure personal safety.

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Formation of Ordered Biomolecular Structures by the Self-assembly of Short Peptides

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control self-assembly and mimicking this process in vitro will bring about major advances in the areas of materials science and nanotechnology. Among the available biological building blocks, peptides have several advantages as they present substantial diversity, their synthesis in large scale is straightforward, and they can easily be modified with biological and chemical entities1,2. Several classes of designed peptides such as cyclic peptides, amphiphile peptides and peptide-conjugates self-assemble into ordered structures in solution. Homoaromatic dipeptides, are a class of short self-assembled peptides that contain all the molecular information needed to form ordered structures such as nanotubes, spheres and fibrils3-8. A large variety of these peptides is commercially available.
This paper presents a procedure that leads to the formation of ordered structures by the self-assembly of homoaromatic peptides. The protocol requires only commercial reagents and basic laboratory equipment. In addition, the paper describes some of the methods available for the characterization of peptide-based assemblies. These methods include electron and atomic force microscopy and Fourier-Transform Infrared Spectroscopy (FT-IR). Moreover, the manuscript demonstrates the blending of peptides (coassembly) and the formation of a &#34;beads on a string&#34;-like structure by this process.9 The protocols presented here can be adapted to other classes of peptides or biological building blocks and can potentially lead to the discovery of new peptide-based structures and to better control of their assembly.

This paper describes the formation of highly ordered peptide-based structures by the spontaneous process of self-assembly. The method utilizes commercially available peptides and common lab equipment. This technique can be applied to a large variety of peptides and may lead to the discovery of new peptide-based assemblies.

In nature, complex functional structures are formed by the self-assembly of biomolecules under mild conditions. Understanding the forces that control ...

Chemical Gardens as Flow-through Reactors Simulating Natural Hydrothermal Systems

Here we report experimental simulations of hydrothermal chimney growth using injection chemical garden methods. The versatility of this type of experiment allows for testing of various proposed ocean / hydrothermal fluid chemistries that could have driven reactions toward the origin of life in environments on the early Earth, early Mars, or even other worlds such as the icy moons of the outer planets. We show experiments that include growth of chemical garden structures under anoxic conditions simulating the early Earth, inclusion of trace components of phosphates / organics in the injection solution to incorporate them into the structure, a switch of the injection solution to introduce a secondary precipitating anion, and the measurement of membrane potentials generated by chemical gardens. Using this method, self-assembling chemical garden structures were formed that mimic the natural chimneys precipitated at submarine hydrothermal springs, and these precipitates can be used successfully as flow-through reactors by feeding through multiple successive &#8220;hydrothermal&#8221; injections.

We describe chemical garden formation via injection experiments that allow for laboratory simulations of natural chemical garden systems that form at submarine hydrothermal vents.

Here we report experimental simulations of hydrothermal chimney growth using injection chemical garden methods. The versatility of this type of experiment ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Preparation of Biopolymer Aerogels Using Green Solvents

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm3), high specific surface area (350 - 500 m2/g) and pore volume (3 - 7 cm3/g for pore sizes less than 150 nm).

A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers ...

Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand

A simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, 1,4-benzene-bis(iminoguanidinium) (BBIG), is demonstrated. The ligand is synthesized as the chloride salt (BBIG-Cl) by in situ imine condensation of terephthalaldehyde with aminoguanidinium chloride in water, followed by crystallization as the sulfate salt (BBIG-SO4). Alternatively, BBIG-Cl is synthesized ex situ in larger scale from ethanol. The sulfate separation ability of the BBIG ligand is demonstrated by selective and quantitative crystallization of sulfate from seawater. The ligand can be recycled by neutralization of BBIG-SO4 with aqueous NaOH and crystallization of the neutral bis-iminoguanidine, which can be converted back into BBIG-Cl with aqueous HCl and reused in another separation cycle. Finally, 35S-labeled sulfate and &#946; liquid scintillation counting are employed for monitoring the sulfate concentration in solution. Overall, this protocol will instruct the user in the necessary skills to synthesize a ligand, employ it in the selective crystallization of sulfate from aqueous solutions, and quantify the separation efficiency.

A protocol for in situ aqueous synthesis of a bis(iminoguanidinium) ligand and its utilization in selective separation of sulfate is presented.

A simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, ...

Capillary Electrophoresis to Monitor Peptide Grafting onto Chitosan Films in Real Time

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. Compared to other analytical separation techniques, such as chromatography, CE is cheap, robust and effectively requires no sample preparation (for a number of complex natural matrices or polymeric samples). CE is fast and can be used to follow the evolution of mixtures in real time (e.g., chemical reaction kinetics), as the signals observed for the separated compounds are directly proportional to their quantity in solution.
Here, the efficiency of CE is demonstrated for monitoring the covalent grafting of peptides onto chitosan films for subsequent biomedical applications. Chitosan&#39;s antimicrobial and biocompatible properties make it an attractive material for biomedical applications such as cell growth substrates. Covalently grafting the peptide RGDS (arginine - glycine - aspartic acid - serine) onto the surface of chitosan films aims at improving cell attachment. Historically, chromatography and amino acid analysis have been used to provide a direct measurement of the amount of grafted peptide. However, the fast separation and absence of sample preparation provided by CE enables equally accurate yet real-time monitoring of the peptide grafting process. CE is able to separate and quantify the different components of the reaction mixture: the (non-grafted) peptide and the chemical coupling agents. In this way the use of CE results in improved films for downstream applications.
The chitosan films were characterized through solid-state NMR (nuclear magnetic resonance) spectroscopy. This technique is more time-consuming and cannot be applied in real time, but yields a direct measurement of the peptide and thus validates the CE technique.

Free solution capillary electrophoresis is a fast, cheap and robust analytical method that enables the quantitative monitoring of chemical reactions in real time. Its utility for rapid, convenient and precise analysis is demonstrated here through analysis of covalent peptide grafting onto chitosan films for improved cell adhesion.

Free-solution capillary electrophoresis (CE) separates analytes, generally charged compounds in solution through the application of an electric field. ...

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We present methods for depositing and passively manipulating C60 molecules on rippled graphene that advance the pursuit of realizing applications involving 1D C60/graphene hybrid structures. The techniques applied in this exposition are geared towards high vacuum systems with preparation areas capable of supporting molecular deposition as well as thermal annealing of the samples. We focus on C60 deposition at low pressure using a homemade Knudsen cell connected to a scanning tunneling microscopy (STM) system. The number of molecules deposited is regulated by controlling the temperature of the Knudsen cell and the deposition time. One-dimensional (1D) C60 chain structures with widths of two to three molecules can be prepared via tuning of the experimental conditions. The surface mobility of the C60 molecules increases with annealing temperature allowing them to move within the periodic potential of the rippled graphene. Using this mechanism, it is possible to control the transition of 1D C60 chain structures to a hexagonal close packed quasi-1D stripe structure.

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Here we present a protocol for the fabrication of C60/graphene hybrid nanostructures by physical thermal evaporation. Particularly, the proper manipulation of deposition and annealing conditions allow the control over the creation of 1D and quasi 1D C60 structures on rippled graphene.

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We ...

Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain

Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 &#176;C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications.
In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.

Here, we present a protocol for the synthesis of porous barium titanate (BaTiO3) thin film by a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles are used as an organic template.

Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its ...

Separation of Aldehydes and Reactive Ketones from Mixtures Using a Bisulfite Extraction Protocol

The purification of organic compounds is an essential component of routine synthetic operations. The ability to remove contaminants into an aqueous layer by generating a charged structure provides an opportunity to use extraction as a simple purification technique. By combining the use of a miscible organic solvent with saturated sodium bisulfite, aldehydes and reactive ketones can be successfully transformed into charged bisulfite adducts that can then be separated from other organic components of a mixture by the introduction of an immiscible organic layer. Here, we describe a simple protocol for the removal of aldehydes, including sterically-hindered neopentyl aldehydes and some ketones, from chemical mixtures. Ketones can be separated if they are sterically unhindered cyclic or methyl ketones. For aliphatic aldehydes and ketones, dimethylformamide is used as the miscible solvent to improve removal rates. The bisulfite addition reaction can be reversed by basification of the aqueous layer, allowing for the re-isolation of the reactive carbonyl component of a mixture.

Here, we present a protocol to remove aldehydes and reactive ketones from mixtures by a liquid-liquid extraction protocol directly with saturated sodium bisulfite in a miscible solvent. This combined protocol is rapid and facile to perform. The aldehyde or ketone can be re-isolated by the basification of the aqueous layer.

The purification of organic compounds is an essential component of routine synthetic operations. The ability to remove contaminants into an aqueous layer ...

Automated 90Sr Separation and Preconcentration in a Lab-on-Valve System at Ppq Level

A quick, automated and portable system for the separation and determination of radiostrontium in aqueous samples, using Sr-resin and multi sequential flow injection analysis, has been developed. The concentrations of radioactive strontium were determined by flow scintillation counting, allowing for on-line and also on-site determination. The proposed system can determine radioactive strontium at industrial relevant levels without further modification using overall analysis time of less than 10 min per aqueous sample. The limit of the detection is 320 fg&#183;g-1 (1.7 Bq/g).

Automated 90Sr Separation and Preconcentration in a Lab-on-Valve System at Ppq Level

Here, we present the portable autoRAD platform for quick radiometric separation and determination of 90Sr, an important fission product highly pertinent to nuclear waste.

A quick, automated and portable system for the separation and determination of radiostrontium in aqueous samples, using Sr-resin and multi sequential flow ...