FM acknowledges funding from the ANR through a chaire d&#8217;Excellence IDEX Sorbonne Paris Cit&#233;, the INSU through a PNP grant, the Institut Universitaire de France as well as the Labex UniverEarth program at Sorbonne Paris Cit&#233; (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02). We also thank funding from the European Research Council under the European Community&#39;s H2020 framework program/ERC grant agreement #637503 (Pristine).

NOTE: Procedures involving animals have been approved by the Institutional Animal Care and Use Committee (IACUC) at the Universit&#233; Paris Diderot.
1. Preparation of Materials
<ol>
	<li>Sub-boil distill 1 L of the acids (HNO3, HBr) in order to purify them from impurity.</li>
	<li>Clean the beakers and tip adaptor in a hot (~ 100 &#176;C) concentrated HNO3 acid bath for at least two days.</li>
	<li>Wash the pipette tips in a cold 3 N HNO3 bath for several days and rinse individually three times with de-ionized water.</li>
</ol>
2. Sample Preparation
<ol>
	<li>Anesthetize the mice by intraperitoneal injection of ketamine and xylazine. Assess anesthesia by the toe pinch method.</li>
	<li>Collect the blood by a cardiac puncture in the presence of heparin in 1.5 ml tubes.</li>
	<li>Separate the plasma from blood cells by centrifugation (10 min, 1,500 x g) and transfer the plasma to polypropylene cryogenic vials using polypropylene tips.</li>
	<li>Remove the remaining blood from organs by cutting the hepatic vein and injecting DPBS through the heart. Assess death of the mouse by cervical dislocation.</li>
	<li>Harvest the organs with sterile stainless steel instruments, free them of surrounding fat if any, and snap-freeze them in polypropylene cryogenic vials.</li>
</ol>
3. Chemical Purification
<ol>
	<li>First, dissolve the samples in a mix of ~ 1 ml of concentrated (30%) H2O2 and ~ 1 ml of concentrated (~ 15 M) HNO3. Do all these steps inside a fume hood.
	<ol>
		<li>Place the whole organ of interest into a 15 ml Teflon beaker. Then, add the H2O2/HNO3 to the beaker5. Keep the beaker open for a few minutes in order to avoid splashes due to the reaction of oxidation of the organic matter and the release of CO2.</li>
		<li>Finally, put the beaker on a hot plate at about 100 &#176;C for a couple of hours or until the solution is perfectly clear.</li>
	</ol>
	</li>
	<li>Open the beaker and dry the solution on a hot plate at about 100 &#176;C.</li>
	<li>Once the sample is dry, add 1 ml of 1.5 N HBr to the samples; close the beaker and let it dissolve on a hot plate at 100 &#176;C for a couple of hours.</li>
	<li>Meanwhile prepare the 500 &#181;l columns.
	<ol>
		<li>Add 500 &#181;l of the AG1X8 200-400 mesh resin to the column and put it on the column rack with a trash beaker below it. Wash the resin by alternating: 5 ml of 18.2 M&#937; &#8901; cm water, 5 ml of 0.5 N HNO3, 5 ml of water, 5 ml of 0.5 N HNO3, and then 5 ml of water. Condition the resin with 5 ml of 1.5 N HBr.</li>
	</ol>
	</li>
	<li>Remove the beakers from the hot plate and put them in an ultrasonic bath for about 30 min, and then let the beakers cool down to RT.</li>
	<li>Once the beaker is cooled and the resin is washed, open the beaker. Put the tip adaptor to the syringe, add a pipette tip; pipette the 1 ml of sample and load it onto the resin (very slowly in order not to agitate the resin).</li>
	<li>Once all the liquid passes through the column, add 5 ml of 1.5 N HBr.</li>
	<li>Once the 5 ml of 1.5 N HBr pass through the column, replace the trash beaker with a clean 15 ml beaker.</li>
	<li>Add 5 ml of 0.5 N HNO3 2.5 ml at a time. At this stage the Zn is eluted from the resin.</li>
	<li>Once 5 ml of HNO3 passes through the column, remove the beaker and place it on a hot plate at 100 &#176;C until dried.</li>
	<li>Remove the column from the column holder; trash the resin (use a new resin for each sample).</li>
	<li>Once the sample is dry, repeat the protocol with the same volume of acids on a smaller column (100 &#181;l) and then place it on a hot plate until dried. The sample is now ready for mass-spectrometry.</li>
</ol>
4. Mass-spectrometry Measurement
<ol>
	<li>Analyze the Zn isotopic composition on a multi collector-inductively coupled plasma-mass spectrometer (MC-ICP-MS).
	<ol>
		<li>Use the machine parameters summarized in Table 1.</li>
	</ol>
	</li>
	<li>Position the Faraday cups to collect at mass (m/z) of 62Ni, 63Cu, 64Zn, 65Cu, 66Zn, 67Zn and 68Zn.</li>
	<li>Prepare a solution containing 500 ppb Zn in 0.1 M HNO3 for isotopic analysis.</li>
	<li>Analyse the 500 ppb solution of Zn by using a spray chamber combined with a 100 &#181;l/min teflon nebulizer. For each sample, measure 30 scans (1 block of 30 cycles) in which the integration time of each scan is 8.389 sec.</li>
	<li>Correct the background by subtracting the on-peak zero intensities from a blank solution (the 0.1 M HNO3 solution used to re-dissolve the samples).</li>
	<li>Control and correct possible 64Ni isobaric interference by measuring the intensity of the 62Ni peak. Assume that the 64Ni/62Ni ratio is natural (0.2548), correct this value from the instrumental mass bias, and then remove the 64Ni on the mass 64 as: 
	64Znreal= 64Znmeasured - 64Ni = 64Znmeasured - (64Ni/62Ni)natural x 62Nimeasured.</li>
	<li>Correct the instrumental mass bias by bracketing each of the samples with a 500 ppb standard solution of the JMC Lyon Zn standard (or another available standard such as IRMM-3702). Perform the standard bracketing by dividing the 66Zn/64Zn ratio of the sample by the average of the 66Zn/64Zn ratio of the two standards measured before and after the sample minus 1 and multiplied by 1,000 (see Equation 1). Typical external precision on the JMC Lyon Zn standard is 0.05 permil/amu (2 standard deviation, 2 s.d.).</li>
</ol>

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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isotopic+discrimination+of+zinc+in+higher+plants.">Isotopic discrimination of zinc in higher plants.</a> New Phytologist. 165 (3), 703-710 (2005).</li><li>Jouvin, D., Louvat, P., N, M. F. 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The authors have nothing to disclose.

The reproducibility of the measurements is evaluated through replicated analyses of the same samples carried out during different analytical sessions. For example6, we have replicated the same terrestrial rock 7 times and we obtained the results reported in the Table 2.
As expected from the theory of isotopic fractionation10 and as measured in any solar system material so far (e.g.,&#160;meteorite11-13, plants3-5, deep-sea s...

The measurement of high-precision (better than 100 ppm/atomic mass unit) zinc stable isotope composition has only been possible for about 15 years thanks to the development of multi-collector plasma-source mass-spectrometers and has since been mostly applied in Earth and planetary sciences. The applications to the medical field are novel and have a strong potential as biomarkers for diseases that modify the metabolism of zinc (e.g., Alzheimer disease). This paper reports a method to measure with high precision the natural stable isotope ratios of zinc in various mouse organs. The same would be applicable to human samples. The method consists of the dissolution of the organs, the chemical purification of zinc from the rest of the atoms, and then the analysis of the isotope ratio on a mass-spectrometer.
The quality of Zn isotopic measurements is dependent on the quality of the chemical purification (purity of Zn, low blank compared to the amount of Zn present in the sample, high chemical yield of the procedure) and on the control of the instrumental bias. The high purity of the final Zn fraction is needed to remove both isobaric interferences and non-isobaric interference that create a matrix effect. Isobaric nuclides create direct interferences (e.g., 64Ni). Non-isobaric interferences generate the so-called &#8220;matrix&#8221; effect and alter the analytical precision of the measurements by changing the condition of the ionization compared to the pure zinc standard to which the samples are compared to1. A low blank (&#60; 10 ng) indicates that there is no contamination of the samples by external Zn that would bias the measured isotopic composition. As Zn isotopes can be fractionated during ion-exchange chromatography2, the collection of all the Zn atoms ensures that no isotopic fractionation occurs, which implies that the chemical procedure should have a full yield. Finally, the correction of the instrumental isotopic fractionation during the mass-spectrometry measurement is done via the &#8220;standard bracketing&#8221; method.
Therefore, the main difficulties to obtain precise measurements are controlling the external contamination (i.e., low blank), producing a full yield chemical purification that is clean of any other atoms or molecules, and correcting the instrumental isotopic fractionation on the mass-spectrometer. In this paper we will describe our analytical protocol to separate Zn from the mouse organs as well as the mass-spectrometry measurements.
The extraction is done using a low quantity of diluted acids (HBr/HNO3 media) on micro-columns (0.5 &#181;l and 0.1 &#181;l) of anion-exchange resin. It has a full yield and the measurements have an external reproducibility better than 50 ppm on the 66Zn/64Zn ratio. Another advantage of the method is that it is very fast. The method is therefore very well adapted to medical sciences, in which one needs to analyze a large number of samples compared to geosciences, where these analytical methods were developed.

<table border="0" cellpadding="0" cellspacing="0" width="601">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:236px;">Name of Material/ Equipment</td>
			<td style="width:99px;">Company</td>
			<td style="width:99px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:236px;">Multi-collection inductively-coupled-plasma mass-spectromter</td>
			<td style="width:99px;">Thermo-Fisher</td>
			<td style="width:99px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anion-exchange resin AG1 X8 200-400</td>
			<td style="width:99px;">Bio-Rad</td>
			<td colspan="2">140-1443-MSDS</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:236px;">teflon beakers</td>
			<td style="width:99px;">Savillex&#160;</td>
			<td>200-015-12</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:236px;">Home-made teflon colunms made with shrinkable teflon</td>
			<td style="width:99px;"></td>
			<td style="width:99px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

high precision zinc isotopic measurements applied to mouse organs

We present a procedure to measure with high precision zinc isotope ratios in mouse organs. Zinc is composed of 5 stable isotopes (64Zn, 66Zn, 67Zn, 68Zn and 70Zn) which are naturally fractionated between mouse organs. We first show how to dissolve the different organs in order to free the Zn atoms; this step is realized by a mixture of HNO3 and H2O2. We then purify the zinc atoms from all the other elements, in particular from isobaric interferences (e.g., Ni), by anion-exchange chromatography in a dilute HBr/HNO3 medium. These first two steps are performed in a clean laboratory using high purity chemicals. Finally, the isotope ratios are measured by using a multi-collector inductively-coupled-plasma mass-spectrometer, in low resolution. The samples are injected using a spray chamber and the isotopic fractionation induced by the mass-spectrometer is corrected by comparing the ratio of the samples to the ratio of a standard (standard bracketing technique).&#160;This full typical&#160;procedure produces an isotope ratio with a 50 ppm (2 s.d.) reproducibility.

In 1.5 N HBr, the main zinc species (ZnBr3-) forms very strong complexes with the anion-exchange resin, while most other elements do not interact with the resin. Zinc is then recovered by changing the medium to diluted HNO3, changing the speciation of Zn to Zn2+ which is released from the resin6,7.
Isotope ratios are typically expressed as parts per 1,000 deviations relative to a standard:
<img alt="Equation 1" fo:content-width="2.5i...

Watch this Scientific Journal Video about High Precision Zinc Isotopic Measurements Applied to Mouse Organs at JoVE.com

High Precision Zinc Isotopic Measurements Applied to Mouse Organs

We present the technique to measure with high precision zinc isotope ratios in mouse organs.

We present a procedure to measure with high precision zinc isotope ratios in mouse organs. Zinc is composed of 5 stable isotopes (64Zn, 66Zn, 67Zn, 68Zn ...

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7.4K ビュー.  Université Paris Diderot. We present the technique to measure with high precision zinc isotope ratios in mouse organs.

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High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. Specifically, the sapphire cell enables visual data collection from multiple loadings to solve a set of material balances to precisely determine phase composition. Ternary phase diagrams can then be established to determine the proportion of each component in each phase at a given condition. In principle, any ternary system can be studied although ternary systems (gas-liquid-liquid) are the specific examples discussed herein. For instance, the ternary THF-Water-CO2 system was studied at 25 and 40&#160;&#176;C and is described herein. Of key importance, this technique does not require sampling. Circumventing the possible disturbance of the system equilibrium upon sampling, inherent measurement errors, and technical difficulties of physically sampling under pressure is a significant benefit of this technique. Perhaps as important, the sapphire cell also enables the direct visual observation of the phase behavior. In fact, as the CO2 pressure is increased, the homogeneous THF-Water solution phase splits at about 2 MPa. With this technique, it was possible to easily and clearly observe the cloud point and determine the composition of the newly formed phases as a function of pressure.
The data acquired with the sapphire cell technique can be used for many applications. In our case, we measured swelling and composition for tunable solvents, like gas-expanded liquids, gas-expanded ionic liquids and Organic Aqueous Tunable Systems (OATS)1-4. For the latest system, OATS, the high-pressure sapphire cell enabled the study of (1) phase behavior as a function of pressure and temperature, (2) composition of each phase (gas-liquid-liquid) as a function of pressure and temperature and (3) catalyst partitioning in the two liquid phases as a function of pressure and composition. Finally, the sapphire cell is an especially effective tool to gather accurate and reproducible measurements in a timely fashion.

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus is a unique tool to study, without sampling, phase behavior under a wide range of pressures. Using a cathetometer, very precise volume measurements can be recorded to measure liquid expansion and phase composition. Thus, this synthetic method enables the study of (1) phase equilibria of multi-component mixtures and (2) the partition behavior of catalyst or model compounds as a function of pressure.

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. ...

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements are simple high-throughput characterization experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glassy states for a variety of glassy materials. This technique allows for these parameters to be measured in a single experiment, while other methods must combine a variety of different techniques to investigate all of these properties. Measurements of dynamics close to Tg are particularly challenging. The advantage of cooling rate dependent Tg measurements over other methods which directly probe bulk and surface relaxation dynamics is that they are relatively quick and simple experiments, which do not utilize fluorophores or other complicated experimental techniques. Furthermore, this technique probes the average dynamics of technologically relevant thin films in temperature and relaxation time (&#964;&#945;) regimes relevant to the glass transition (&#964;&#945; &#62; 100 sec). The limitation to using ellipsometry for cooling rate dependent Tg experiments is that it cannot probe relaxation times relevant to measurements of viscosity (&#964;&#945; &#60;&#60; 1 sec). Other cooling rate dependent Tg measurement techniques, however, can extend the CR-Tg method to faster relaxation times. Furthermore, this technique can be used for any glassy system so long as the integrity of the film remains throughout the experiment.

Here, we present a protocol for cooling rate dependent ellipsometry experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glass for a variety of glassy materials.

This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements ...

Immunostaining Phospho-epitopes in Ciliated Organs of Whole Mount Zebrafish Embryos

The rapid proliferation of cells, the tissue-specific expression of genes and the emergence of signaling networks characterize early embryonic development of all vertebrates. The kinetics and location of signals - even within single cells - in the developing embryo complements the identification of important developmental genes. Immunostaining techniques are described that have been shown to define the kinetics of intracellular and whole animal signals in structures as small as primary cilia. The techniques for fixing, imaging and processing images using a laser-scanning confocal compound microscope can be completed in as few as 36 hr.
Zebrafish (Danio rerio) is a desirable organism for investigators who seek to conduct studies in a vertebrate species that is affordable and relevant to human disease. Genetic knockouts or knockdowns must be confirmed by the loss of the actual protein product. Such confirmation of protein loss can be achieved using the techniques described here. Clues into signaling pathways can also be deciphered by using antibodies that are reactive with proteins that have been post-translationally modified by phosphorylation. Preserving and optimizing the phosphorylated state of an epitope is therefore critical to this determination and is accomplished by this protocol.
This study describes techniques to fix embryos during the first 72 hr of development and co-localize a variety of relevant epitopes with cilia in the Kupffer&#39;s Vesicle (KV), the kidney and the inner ear. These techniques are straightforward, do not require dissection and can be completed in a relatively short period of time. Projecting confocal image stacks into a single image is a useful means of presenting these data.

Techniques are described to immunostain phospho-epitopes in whole zebrafish embryos and then conduct two-color fluorescent confocal localization in cellular structures as small as primary cilia. The techniques for fixing and imaging can define the location and kinetics of the appearance or activation of specific proteins.

The rapid proliferation of cells, the tissue-specific expression of genes and the emergence of signaling networks characterize early embryonic development ...

Characterization, Quantification and Compound-specific Isotopic Analysis of Pyrogenic Carbon Using Benzene Polycarboxylic Acids (BPCA)

Fire-derived, pyrogenic carbon (PyC), sometimes called black carbon (BC), is the carbonaceous solid residue of biomass and fossil fuel combustion, such as char and soot. PyC is ubiquitous in the environment due to its long persistence, and its abundance might even increase with the projected increase in global wildfire activity and the continued burning of fossil fuel. PyC is also increasingly produced from the industrial pyrolysis of organic wastes, which yields charred soil amendments (biochar). Moreover, the emergence of nanotechnology may also result in the release of PyC-like compounds to the environment. It is thus a high priority to reliably detect, characterize and quantify these charred materials in order to investigate their environmental properties and to understand their role in the carbon cycle.
Here, we present the benzene polycarboxylic acid (BPCA) method, which allows the simultaneous assessment of PyC&#39;s characteristics, quantity and isotopic composition (13C and 14C) on a molecular level. The method is applicable to a very wide range of environmental sample materials and detects PyC over a broad range of the combustion continuum, i.e., it is sensitive to slightly charred biomass as well as high temperature chars and soot. The BPCA protocol presented here is simple to employ, highly reproducible, as well as easily extendable and modifiable to specific requirements. It thus provides a versatile tool for the investigation of PyC in various disciplines, ranging from archeology and environmental forensics to biochar and carbon cycling research.

Characterization, Quantification and Compound-specific Isotopic Analysis of Pyrogenic Carbon Using Benzene Polycarboxylic Acids BPCA

We present the benzene polycarboxylic acid (BPCA) method for assessing pyrogenic carbon (PyC) in the environment. The compound-specific approach uniquely provides simultaneous information about the characteristics, quantity and isotopic composition (13C and 14C) of PyC.

Fire-derived, pyrogenic carbon (PyC), sometimes called black carbon (BC), is the carbonaceous solid residue of biomass and fossil fuel combustion, such as ...

Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to the gas phase, and efficiently transferred to a detection system. Fizzy extraction takes advantage of the effervescence phenomenon. First, a carrier gas (here, carbon dioxide) is dissolved in the sample by applying overpressure and stirring the sample. Second, the sample chamber is decompressed abruptly. Decompression leads to the formation of numerous carrier gas bubbles in the sample liquid. These bubbles assist the release of the dissolved analyte species from the liquid to the gas phase. The released analytes are immediately transferred to the atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. The ionizable analyte species give rise to mass spectrometric signals in the time domain. Because the release of the analyte species occurs over short periods of time (a few seconds), the temporal signals have high amplitudes and high signal-to-noise ratios. The amplitudes and areas of the temporal peaks can then be correlated with concentrations of the analytes in the liquid samples subjected to fizzy extraction, which enables quantitative analysis. The advantages of fizzy extraction include: simplicity, speed, and limited use of chemicals (solvents).

Fizzy extraction is a new laboratory technique for analysis of volatile and semivolatile compounds. A carrier gas is dissolved in the liquid sample by applying overpressure and stirring the sample. The sample chamber is then decompressed. The analyte species are liberated to the gas phase due to effervescence.

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to ...

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, their high cost production and/or incompatibility with microfabrication technologies, due to the use of pre-deposited catalyst-seeds and/or high processing temperatures exceeding 900 &#176;C, represent a drawback for a widespread use of these methods. Here, however, we report the synthesis of ZnO rods via a non-catalyzed vapor-solid mechanism enabled by using an aerosol-assisted chemical vapor deposition (CVD) method at 400 &#176;C with zinc chloride (ZnCl2) as the precursor and ethanol as the carrier solvent. This method provides both single-step formation of ZnO rods and the possibility of their direct integration with various substrate types, including silicon, silicon-based micromachined platforms, quartz, or high heat resistant polymers. This potentially facilitates the use of this method at a large-scale, due to its compatibility with state-of-the-art microfabrication processes for device manufacture. This report also describes the properties of these structures (e.g., morphology, crystalline phase, optical band gap, chemical composition, electrical resistance) and validates its gas sensing functionality towards carbon monoxide.

Columnar zinc oxide structures in the form of rods are synthesized via aerosol-assisted chemical vapor deposition without the use of pre-deposited catalyst-seed particles. This method is scalable and compatible with various substrates based on either silicon, quartz or polymers.

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, ...

High Resolution Physical Characterization of Single Metallic Nanoparticles

Individual molecules can be detected and characterized by measuring the degree by which they reduce the ionic current flowing through a single nanometer-scale pore. The signal is characteristic of the molecule&#39;s physicochemical properties and its interactions with the pore. We demonstrate that the nanopore formed by the bacterial protein exotoxin Staphylococcus aureus alpha hemolysin (&#945;HL) can detect polyoxometalates (POMs, anionic metal oxygen clusters), at the single molecule limit. Moreover, multiple degradation products of 12-phosphotungstic acid POM (PTA, H3PW12O40) in solution are simultaneously measured. The single molecule sensitivity of the nanopore method allows for POMs to be characterized at significantly lower concentrations than required for nuclear magnetic resonance (NMR) spectroscopy. This technique could serve as a new tool for chemists to study the molecular properties of polyoxometalates or other metallic clusters, to better understand POM synthetic processes, and possibly improve their yield. Hypothetically, the location of a given atom, or the rotation of a fragment in the molecule, and the metal oxidation state could be investigated with this method. In addition, this new technique has the advantage of allowing the real-time monitoring of molecules in solution.&#160;

Here, we present a protocol to detect discrete metal oxygen clusters, polyoxometalates (POMs), at the single molecule limit using a biological nanopore-based electronic platform. The method provides a complementary approach to traditional analytical chemistry tools used in the study of these molecules.

Individual molecules can be detected and characterized by measuring the degree by which they reduce the ionic current flowing through a single ...

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method

The single deuterium substitution in porphycene leads to an asymmetric molecular geometry, which may affect the double proton transfer process in the porphycene molecule. In this study, we applied an enhanced QM/MM method called SITS-QM/MM to investigate hydrogen/deuterium (H/D) isotope effects on the double proton transfer in porphycene. Distance changes in SITS-QM/MM molecular dynamics simulations suggested that the deuterium substituted porphycene adopted the stepwise double proton transfer mechanism. The structural analysis and the free energy shifts of double proton transfer process indicated that the asymmetric isotopic substitution subtly compressed the covalent hydrogen bonds and may alter the original transition state location.

A protocol that uses enhanced QM/MM method to investigate the isotopic effect on the double proton transfer process in porphycene is presented here.

The single deuterium substitution in porphycene leads to an asymmetric molecular geometry, which may affect the double proton transfer process in the ...

Automated Sample Multiplexing by using Combined Precursor Isotopic Labeling and Isobaric Tagging (cPILOT)

We have introduced a high throughput quantitative proteomics workflow, combined precursor isotopic labeling and isobaric tagging (cPILOT) capable of multiplexing up to 22 or 24 samples with tandem mass tags or isobaric N,N-dimethyl leucine isobaric tags, respectively, in a single experiment. This enhanced sample multiplexing considerably reduces mass spectrometry acquisition times and increases the utility of the expensive commercial isobaric reagents. However, the manual process of sample handling and pipetting steps in the strategy can be labor intensive, time consuming, and introduce sample loss and quantitative error. These limitations can be overcome through the incorporation of automation. Here we transferred the manual cPILOT protocol to an automated liquid handling device that can prepare large sample numbers (i.e., 96 samples) in parallel. Overall, automation increases feasibility and reproducibility of cPILOT and allows for broad usage by other researchers with comparable automation devices.

Automated Sample Multiplexing by using Combined Precursor Isotopic Labeling and Isobaric Tagging cPILOT

Combined precursor isotopic labeling and isobaric tagging (cPILOT) is an enhanced sample multiplexing strategy that is capable of increasing the number of samples that can be analyzed simultaneously with available isobaric tags. Incorporation of a robotic platform has greatly increased experimental throughput, reproducibility, and quantitative accuracy.

We have introduced a high throughput quantitative proteomics workflow, combined precursor isotopic labeling and isobaric tagging (cPILOT) capable of ...

Zinc-Sponge Battery Electrodes that Suppress Dendrites

We report two methods to create zinc-sponge electrodes that suppress dendrite formation and shape change for rechargeable zinc batteries. Both methods are characterized by creating a paste made of zinc particles, organic porogen, and viscosity-enhancing agent that is heated under an inert gas and then air. During heating under the inert gas, the zinc particles anneal together, and the porogen decomposes; under air, the zinc fuses and residual organic burns out, yielding an open-cell metal foam or sponge. We tune the mechanical and electrochemical properties of the zinc sponges by varying zinc-to-porogen mass ratio, heating time under inert gas and air, and size and shape of the zinc and porogen particles. An advantage of the reported methods is their ability to finely tune zinc-sponge architecture. The selected size and shape of the zinc and porogen particles influence the morphology of the pore structure. A limitation is that resulting sponges have disordered pore structures that result in low mechanical strength at low volume fractions of zinc (&#60;30%). Applications for these zinc-sponge electrodes include batteries for grid-storage, personal electronics, electric vehicles, and electric aviation. Users can expect zinc-sponge electrodes to cycle up to 40% depth of discharge at technologically relevant rates and areal capacities without the formation of separator-piercing dendrites.

The goal of the reported protocols is to create rechargeable zinc-sponge electrodes that suppress dendrites and shape change in zinc batteries, such as nickel&#8211;zinc or zinc&#8211;air.

We report two methods to create zinc-sponge electrodes that suppress dendrite formation and shape change for rechargeable zinc batteries. Both methods are ...