FM riconosce finanziamenti dal ANR attraverso una poltrona d&#39;Excellence IDEX Sorbonne Paris Cité, il INSU attraverso una sovvenzione PNP, l&#39;Institut Universitaire de France, così come il programma LABEX UniverEarth alla Sorbona di Parigi Cité (ANR-10-LabX-0023 e ANR -11-IDEX-0005-02). Ringraziamo anche il finanziamento da parte del Consiglio europeo della ricerca nell&#39;ambito della Comunità europea H2020 programma quadro / ERC convenzione di sovvenzione # 637503 (Pristine).

NOTA: Le procedure che coinvolgono gli animali sono stati approvati dalla cura e l&#39;uso Comitato Istituzionale Animal (IACUC) presso l&#39;Université Paris Diderot. 1. Preparazione dei materiali <ol><li> Sub-ebollizione distillare 1 L degli acidi (HNO 3, HBr) per purificarli da impurità. </li><li> Pulire i bicchieri e l&#39;adattatore punta in un caldo (~ 100 ° C) concentrati HNO 3 bagno di acido per almeno due giorni. </li><li> Lavare i puntali delle pipette in una fredda 3 N HNO 3 bagno per diversi giorni e risciacquare singolarmente per tre volte con acqua deionizzata. </li></ol> Preparazione 2. campione <ol><li> Anestetizzare i topi mediante iniezione intraperitoneale di ketamina e xilazina. Valutare l&#39;anestesia con il metodo pizzico piedi. </li><li> Raccogliere il sangue da una puntura cardiaca in presenza di eparina in provette da 1,5 ml. </li><li> Separare il plasma dalle cellule ematiche mediante centrifugazione (10 min, 1.500 xg) e trasferire il plasma al polipropilene cfiale ryogenic con punte di polipropilene. </li><li> Rimuovere il sangue rimanente dagli organi tagliando la vena epatica e l&#39;iniezione DPBS attraverso il cuore. Valutare la morte del mouse per dislocazione cervicale. </li><li> Raccogliere le organi con strumenti sterili in acciaio inox, liberarli di circondare grasso, se del caso, e scatto-congelare in polipropilene fiale criogeniche. </li></ol> 3. Chemical Purificazione <ol><li> Innanzitutto, sciogliere i campioni in un mix di ~ 1 ml di concentrato (30%) H 2 O 2 e ~ 1 ml di concentrato (~ 15 M) HNO 3. Fare tutti questi passaggi all&#39;interno di una cappa aspirante. <ol><li> Inserire l&#39;intero organo di interesse in un becher da 15 ml Teflon. Quindi, aggiungere l&#39;H 2 O 2 / HNO 3 nel becher 5. Mantenere la coppa aperta per pochi minuti per evitare spruzzi dovuti alla reazione di ossidazione della sostanza organica e il rilascio di CO 2. </li><li> Infine, mettere il bicchiere su un piatto caldo a about 100 ° C per un paio d&#39;ore o fino a quando la soluzione è perfettamente chiaro. </li></ol></li><li> Aprire il becher e asciugare la soluzione su una piastra calda a circa 100 ° C. </li><li> Una volta che il campione è asciutto, aggiungere 1 ml di 1,5 N HBr ai campioni; chiudere il bicchiere e farlo sciogliere su una piastra calda a 100 ° C per due ore. </li><li> Nel frattempo preparare le 500 colonne microlitri. <ol><li> Aggiungere 500 ml di resina maglia AG1X8 200-400 alla colonna e metterlo sulla cremagliera colonna con un bicchiere rifiuti sotto. Lavare la resina alternando: 5 ml di 18,2 MW ⋅ cm di acqua, 5 ml di 0,5 N HNO 3, 5 ml di acqua, 5 ml di 0,5 N HNO 3, e poi 5 ml di acqua. Condizionare la resina con 5 ml di 1,5 N HBr. </li></ol></li><li> Togliere i bicchieri dal piatto caldo e metterli in un bagno ad ultrasuoni per circa 30 minuti, e poi lasciare che i bicchieri raffreddare a temperatura ambiente. </li><li> Una volta che il bicchiere viene raffreddata e si lava la resina, aprire il becher. Mettere l&#39;adattatore punta a tegli siringa, aggiungere una punta della pipetta; pipettare i 1 ml di campione e caricarlo sulla resina (molto lentamente per non agitare la resina). </li><li> Una volta che tutto il liquido passa attraverso la colonna, aggiungere 5 ml di 1,5 N HBr. </li><li> Una volta che i 5 ml di 1,5 N HBr passano attraverso la colonna, sostituire il becher cestino con un bicchiere pulito 15 ml. </li><li> Aggiungere 5 ml di 0,5 N HNO 3 2,5 ml per volta. In questa fase l&#39;Zn viene eluito dalla resina. </li><li> Una volta 5 ml di HNO 3 passa attraverso la colonna, togliere il beaker e posizionarlo su una piastra calda a 100 ° C fino essiccato. </li><li> Rimuovere la colonna dal supporto della colonna; cestinare la resina (utilizzare una nuova resina per ogni campione). </li><li> Una volta che il campione è asciutto, ripetere il protocollo con lo stesso volume di acidi su una colonna più piccola (100 microlitri) e poi posto su una piastra calda fino essiccato. Il campione è ora pronto per spettrometria di massa. </li></ol> 4. spettrometria di massa di misura <ol><li> Analizzare il compo isotopica Znsizione su un plasma-spettrometro di massa a più collettore ad accoppiamento induttivo (MC-ICP-MS). <ol><li> Utilizzare i parametri macchina riassunti nella tabella 1. </li></ol></li><li> Posizionare le tazze di Faraday per raccogliere in massa (m / z) di 62 Ni, 63 Cu, Zn 64, 65 Cu, Zn 66, 67 e 68 Zn Zn. </li><li> Preparare una soluzione contenente 500 ppb Zn in 0.1 M HNO 3 per l&#39;analisi isotopica. </li><li> Analizzare la soluzione 500 ppb di Zn utilizzando una camera di nebulizzazione combinato con 100 microlitri / min nebulizzatore teflon. Per ogni campione, misura 30 scansioni (1 blocco di 30 cicli) in cui il tempo di integrazione di ogni scansione è 8,389 sec. </li><li> Correggere il fondo sottraendo i on-picco a zero intensità da una soluzione in bianco (la M HNO soluzione 0,1 3 utilizzati per ri-sciogliere i campioni). </li><li> Controllo e corretta possibile 64 Ni interferenze isobarica misurando l&#39;intensità del picco 62 Ni.Si supponga che il / 62 rapporto Ni 64 Ni è naturale (0,2548), correggere questo valore dal pregiudizio di massa strumentale, e quindi rimuovere il 64 Ni sulla massa 64 come: 64 Zn reale = 64 Zn misurato - 64 Ni = 64 Zn misurato - (64 Ni / 62 Ni) naturale x 62 Ni misurato. </li><li> Correggere la distorsione di massa strumentale di bracketing ciascuno dei campioni con una soluzione 500 ppb standard della norma JMC Lione Zn (o un altro standard disponibile come IRMM-3702). Eseguire il bracketing serie dividendo il rapporto 66 Zn / Zn 64 del campione per la media del rapporto 66 Zn / Zn 64 delle due norme misurati prima e dopo il campione meno 1 e moltiplicato per 1.000 (vedere equazione 1). Tipico precisione esterno sullo standard JMC Lione Zn è di 0,05 per mille / amu (2 deviazioni standard, 2 sd). </li></ol>

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Gli autori non hanno nulla da rivelare.

La riproducibilità delle misure viene valutata mediante analisi replicate degli stessi campioni sono effettuati durante diverse sessioni analitiche. Ad esempio 6, abbiamo replicato stessa roccia terrestre 7 volte e abbiamo ottenuto i risultati riportati nella Tabella 2. Come previsto dalla teoria di frazionamento isotopico 10 e misurata in qualsiasi materiale sistema solare finora (ad esempio, 11-13 meteoriti, piante 3-5,...

La misura di alta precisione (migliore di 100 ppm / unità di massa atomica) zinco composizione isotopica stabile è stato possibile solo per circa 15 anni grazie allo sviluppo di multi-collettore plasma-source spettrometri di massa e da allora è stato in gran parte applicata in Terra e delle scienze planetarie. Le applicazioni al campo medico sono nuovi e hanno un forte potenziale come biomarcatori per le malattie che modificano il metabolismo di zinco (ad esempio, il morbo di Alzheimer). Questo lavoro riporta un metodo per misurare con elevata precisione i naturali rapporti dell&#39;isotopo stabili di zinco in vari organi di topo. Lo stesso sarebbe applicabile a campioni umani. Il metodo consiste nella dissoluzione degli organi, la depurazione chimica dello zinco dal resto degli atomi, e quindi l&#39;analisi del rapporto isotopico su un spettrometro di massa. La qualità delle misure isotopiche Zn dipende dalla qualità della depurazione chimica (purezza di Zn, bassa comp vuotoared alla quantità di Zn presente nel campione, alta resa chimica della procedura) e sul controllo della polarizzazione strumentale. È necessaria la elevata purezza della frazione Zn finale per rimuovere sia le interferenze isobariche e le interferenze non isobarico che creano un effetto matrice. Nuclidi isobariche creano interferenze dirette (ad esempio, 64 Ni). Interferenze non isobariche generare il cosiddetto effetto &quot;matrice&quot; alterano la precisione analitica delle misurazioni cambiando la condizione di ionizzazione rispetto allo standard di zinco puro a cui sono confrontate a 1. Un basso vuoto (&lt;10 ng) indica che non vi è alcuna contaminazione dei campioni da Zn esterno che sarebbe influenzare la composizione isotopica misurata. Come isotopi Zn possono essere frazionati durante cromatografia a scambio ionico 2, l&#39;insieme di tutti gli atomi di Zn assicura che non si verifica alcun frazionamento isotopico, che implica che il procedimento chimico dovrebbe avere un rendimento completo. Infine, la correzione del frazionamento isotopico strumentale durante la misurazione spettrometria di massa è fatto tramite il metodo &quot;staffaggio standard&quot;. Pertanto, le principali difficoltà per ottenere misure precise controllano la contaminazione esterna (cioè basso vuoto), producendo una piena resa depurazione chimica che è pulito di altri atomi o molecole, e correggendo il frazionamento isotopico strumentale sul spettrometro di massa. In questo articolo descriveremo il nostro protocollo analitico per separare Zn dagli organi di topo e le misure di spettrometria di massa. L&#39;estrazione viene fatto utilizzando una bassa quantità di acidi diluiti (HBr / HNO 3 media) su micro-colonne (0,5 microlitri e 0,1 microlitri) di resina a scambio anionico. Ha una resa completa e le misurazioni hanno una riproducibilità esterna superiore a 50 ppm dal rapporto 66 Zn / Zn 64. Un altro vantaggio del method è che è molto veloce. Il metodo è quindi molto ben adattato alle scienze mediche, in cui si ha la necessità di analizzare un gran numero di campioni rispetto al geosciences, dove sono stati sviluppati questi metodi analitici.

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			<td style="width:167px;">Comments/Description</td>
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			<td height="42" style="height:42px;width:236px;">Multi-collection inductively-coupled-plasma mass-spectromter</td>
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			<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>
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			<td height="21" style="height:21px;width:236px;">teflon beakers</td>
			<td style="width:99px;">Savillex&#160;</td>
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			<td height="42" style="height:42px;width:236px;">Home-made teflon colunms made with shrinkable teflon</td>
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high precision zinc isotopic measurements applied to mouse organs

Vi presentiamo una procedura per misurare con elevata precisione i rapporti isotopici di zinco negli organi di topo. Lo zinco è composto da 5 isotopi stabili (64 Zn, Zn 66, 67, 68 Zn Zn e 70 Zn) che sono naturalmente frazionati tra gli organi del mouse. Per prima cosa mostriamo come sciogliere i diversi organi, al fine di liberare gli atomi Zn; questo passaggio è realizzato da una miscela di HNO 3 e H 2 O 2. Abbiamo poi purificare gli atomi di zinco da tutti gli altri elementi, in particolare da interferenze isobariche (ad esempio, Ni), mediante cromatografia a scambio anionico in un diluita HBr / HNO 3 medio. Questi primi due passaggi vengono eseguiti in un laboratorio pulito utilizzo di prodotti chimici di elevata purezza. Infine, i rapporti isotopici sono misurati utilizzando un multi-collettore accoppiato induttivamente-plasma spettrometro di massa, in bassa risoluzione. I campioni sono iniettati usando una camera di nebulizzazione e frazionamento isotopico indotto dalla spettrometro di massa è correcta confrontando il rapporto dei campioni al rapporto di uno standard (tecnica bracketing standard). Questo procedimento tipico completo produce un rapporto isotopico con un 50 ppm (2 sd) riproducibilità.

In 1.5 N HBr, le principali specie di zinco (ZnBr3-) forma complessi molto forti con la resina scambiatrice di anioni, mentre la maggior parte degli altri elementi non interagiscono con la resina. Lo zinco viene quindi recuperato cambiando medio HNO 3 diluito, cambiando la speciazione di Zn di Zn 2+ che si libera dal 6,7 resina. Rapporti isotopici sono tipicamente espressi come parti per 1.000 deviazioni relative a uno standard: <i...

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.

Alte le misure di precisione di zinco isotopiche applicate a mouse Organi

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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JoVE Journal

Chemistry

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

Video: High Precision Zinc Isotopic Measurements Applied to Mouse Organs

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.

Ad alta pressione Sapphire cellulare per la fase Equilibri misurazioni di CO<sub&gt; 2</sub&gt; / biologici / Water Systems

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

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Chimica

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.

Raffreddamento Vota dipendenti Misure ellissometria per determinare la dinamica dei Thin Films Glassy

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.

Immunocolorazione fosfo-epitopi in Ciliated Organi di monte intero embrioni di zebrafish

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.

Caratterizzazione, quantificazione e specifici Compound isotopica analisi di Pirogenica di carbonio utilizzando Benzene Polycarboxylic Acidi (BPCA)

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

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.

Aerosol-assisted Chemical Vapor Deposition di strutture in ossido di metallo: aste di ossido di zinco

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.

Caratterizzazione fisica ad alta risoluzione di nanoparticelle metalliche singole

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.

Effetto isotopico nel processo di trasferimento di doppio protone di porficene indagato dal metodo QM/MM migliorato

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.

Multiplexing di campioni automatizzato utilizzando l'etichettatura isotopica precursore combinata e il tagging isobarico (cPILOT)

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.

Elettrodi per batterie in spugna di zinco che sopprimono i dendriti

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

Picometer-Precision Atomic Position Tracking through Electron Microscopy

The modern aberration-corrected scanning transmission electron microscopes (AC-STEM) have successfully achieved direct visualization of atomic columns with sub-angstrom resolution. With this significant progress, advanced image quantification and analysis are still at the early stages. In this work, we present the complete pathway for the metrology of atomic resolution scanning transmission electron microscopy (STEM) images. This includes (1) tips for acquiring high-quality STEM images; (2) denoising and drift-correction for enhancing measurement accuracy; (3) obtaining initial atomic positions; (4) indexing the atoms based on unit cell vectors; (5) quantifying the atom column positions with either 2D-Gaussian single peak fitting or (6) multi-peak fitting routines for slightly overlapping atomic columns; (7) quantification of lattice distortion/strain within the crystal structures or at the defects/interfaces where the lattice periodicity is disrupted; and (8) some common methods to visualize and present the analysis.
Furthermore, a simple self-developed free MATLAB app (EASY-STEM) with a graphical user interface (GUI) will be presented. The GUI can assist in the analysis of STEM images without the need for writing dedicated analysis code or software. The advanced data analysis methods presented here can be applied for the local quantification of defect relaxations, local structural distortions, local phase transformations, and non-centrosymmetry in a wide range of materials.

This work presents a workflow for atomic position tracking in atomic resolution transmission electron microscopy imaging. This workflow is performed using an open-source Matlab app (EASY-STEM).

Tracciamento della posizione atomica picometro-precisione attraverso la microscopia elettronica

The modern aberration-corrected scanning transmission electron microscopes (AC-STEM) have successfully achieved direct visualization of atomic columns ...