FM reconnaît le financement de l&#39;ANR par une chaire d&#39;excellence IDEX Sorbonne Paris Cité, l&#39;INSU grâce à une subvention PNP, l&#39;Institut Universitaire de France, ainsi que le programme Labex UniverEarth à la Sorbonne Paris Cité (ANR-10-LabX-0023 et l&#39;ANR -11-IDEX-0005-02). Nous remercions également le financement du Conseil européen de la recherche sous H2020 programme-cadre / ERC convention de subvention N ° 637503 la Communauté européenne (Pristine).

Nota: Les procédures impliquant des animaux ont été approuvés par le Comité institutionnel de protection des animaux et l&#39;utilisation (IACUC) à l&#39;Université Paris Diderot. 1. Préparation des matériaux <ol><li> Sous-distiller ébullition 1 litre d&#39;acides (HNO 3, HBr) afin de les purifier de l&#39;impureté. </li><li> Nettoyez les béchers et pourboire adaptateur dans un chaud (~ 100 ° C) concentrés HNO 3 bain d&#39;acide pour au moins deux jours. </li><li> Laver les embouts de pipette dans un froid 3 N HNO 3 salles de bain pendant plusieurs jours et rincer individuellement trois fois avec de l&#39;eau déminéralisée. </li></ol> Préparation de l&#39;échantillon 2. <ol><li> Anesthésier les souris par injection intraperitoneale de kétamine et de xylazine. Évaluer l&#39;anesthésie par la méthode orteil de pincement. </li><li> Recueillir le sang par une ponction cardiaque en présence d&#39;héparine dans 1,5 ml tubes. </li><li> Séparer le plasma des globules par centrifugation (10 min, 1500 x g) et transférer le plasma de polypropylene cflacons ryogenic aide des conseils de polypropylène. </li><li> Retirer le reste du sang à partir d&#39;organes en coupant la veine hépatique et l&#39;injection DPBS à travers le cœur. Évaluer la mort de la souris par dislocation cervicale. </li><li> Récolter les organes avec des instruments en acier inoxydable stériles, les libérer de la graisse entourant le cas échéant, et Snap-les congeler dans des flacons cryogéniques en polypropylène. </li></ol> 3. Chemical Purification <ol><li> Tout d&#39;abord, dissoudre les échantillons dans un mélange de ~ 1 ml de concentré (30%) H 2 O 2 et ~ 1 ml de concentré (~ 15 M) HNO 3. Faire toutes ces étapes à l&#39;intérieur d&#39;une hotte. <ol><li> Placer l&#39;ensemble organe d&#39;intérêt dans un bécher de 15 ml en Teflon. Ensuite, ajouter le H 2 O 2 / HNO 3 dans le bêcher 5. Conserver le bêcher ouvert pendant quelques minutes afin d&#39;éviter les éclaboussures dues à la réaction d&#39;oxydation de la matière organique et la libération de CO 2. </li><li> Enfin, mettre le bécher sur une plaque chaude à about 100 ° C pendant une couple d&#39;heures ou jusqu&#39;à ce que la solution est parfaitement clair. </li></ol></li><li> Ouvrez le bécher et sécher la solution sur une plaque chauffante à environ 100 ° C. </li><li> Une fois que l&#39;échantillon est sec, ajouter 1 ml de 1,5 N HBr aux échantillons; fermer le bêcher et laisser dissoudre sur une plaque chaude à 100 ° C pendant une couple d&#39;heures. </li><li> Pendant ce temps préparer les 500 colonnes ul. <ol><li> Ajouter 500 ul de la résine de 200-400 mesh AG1X8 à la colonne et le mettre sur la crémaillère de la colonne avec un bêcher de déchets au-dessous. Laver la résine en alternant: 5 18,2 ml d&#39;eau MQ ⋅ cm, 5 ml de HNO 3 0,5 N, 5 ml d&#39;eau, 5 ml de HNO 3 0,5 N, puis 5 ml d&#39;eau. Conditionner la résine avec 5 ml de 1,5 N HBr. </li></ol></li><li> Retirez les béchers de la plaque chaude et mettez-les dans un bain à ultrasons pendant environ 30 min, puis laissez-les béchers refroidir à température ambiante. </li><li> Une fois que le récipient est refroidi et la résine est lavée, ouvrir le récipient. Mettez l&#39;adaptateur de pointe à til seringue, ajouter une pointe de pipette; pipette de 1 ml de l&#39;échantillon et le charger sur la résine (très lentement afin de ne pas agiter la résine). </li><li> Une fois que tout le liquide passe à travers la colonne, ajouter 5 ml de 1,5 N HBr. </li><li> Une fois les 5 ml de 1,5 N HBr passent à travers la colonne, remplacer le bécher de poubelle avec un chiffon propre 15 ml bécher. </li><li> Ajouter 5 ml de HNO 3 0,5 N 2,5 ml à la fois. A ce stade, le Zn est éluée de la résine. </li><li> Une fois 5 ml de HNO 3 passe à travers la colonne, retirer le bécher et le placer sur une plaque chaude à 100 ° C jusqu&#39;à ce que séché. </li><li> Retirer la colonne de support de la colonne; corbeille de la résine (utiliser une nouvelle résine pour chaque échantillon). </li><li> Une fois que l&#39;échantillon est sec, répéter le protocole avec le même volume d&#39;acides sur une colonne plus petite (100 pi), puis placez-le sur une plaque chaude jusqu&#39;à séché. L&#39;échantillon est maintenant prêt pour la spectrométrie de masse. </li></ol> 4. spectrométrie de masse Mesure <ol><li> Analyser le compo isotopique Znsition sur un spectromètre multi masse à plasma à couplage inductif-collecteur (MC-ICP-MS). <ol><li> Utilisez les paramètres de la machine résumées dans le tableau 1. </li></ol></li><li> Placez les cages de Faraday pour recueillir à la messe (m / z) de 62 Ni, 63 Cu, Zn 64, 65 Cu, Zn 66, 67 et 68 Zn Zn. </li><li> Préparer une solution contenant 500 ppb Zn dans 0,1 M HNO 3 à l&#39;analyse isotopique. </li><li> Analyse de la solution de 500 ppb de Zn à l&#39;aide d&#39;une chambre de pulvérisation associé à un 100 ul / min téflon nébuliseur. Pour chaque échantillon, mesurer 30 balayages (1 bloc de 30 cycles) dans lequel le temps d&#39;intégration de chaque balayage est 8.389 sec. </li><li> Corrigez l&#39;arrière-plan en soustrayant les sur-intensités crête zéro à partir d&#39;une solution à blanc (M HNO 3 de solution à 0,1 utilisé pour re-dissoudre les échantillons). </li><li> Le contrôle et la possible interférence 64 Ni isobare correct en mesurant l&#39;intensité du pic 62 Ni.Supposons que le / 62 64 rapport Ni Ni est naturel (0,2548), cette valeur correcte de la polarisation de la masse instrumentale, puis retirez le 64 Ni sur la masse 64 que: 64 Zn réelle = 64 Zn mesurée - 64 Ni = 64 Zn mesurée - (64 Ni / 62 Ni) naturelle x 62 Ni mesurée. </li><li> Corrigez le biais de masse instrumentale par bracketing chacun des échantillons avec une solution 500 ppb niveau de la norme JMC Lyon Zn (ou un autre standard disponibles comme IRMM-3702). Effectuer le bracketing norme en divisant le 66 Zn / 64 Zn de l&#39;échantillon par la moyenne des 66 Zn / 64 Zn des deux normes mesurées avant et après l&#39;échantillon moins 1 et multiplié par 1.000 (voir l&#39;équation 1). Précision externe typique sur la norme JMC Lyon Zn est de 0,05 permil / uma (2 écart-type, 2 sd). </li></ol>

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Les auteurs ont rien à révéler.

La reproductibilité des mesures est évaluée par des analyses répliquées des mêmes échantillons effectuées au cours des différentes sessions d&#39;analyse. Par exemple 6, nous avons reproduit la même roche terrestre 7 fois et nous avons obtenu les résultats présentés dans le Tableau 2. Comme prévu à partir de la théorie de fractionnement isotopique 10 et mesurée dans tout matériel du système solaire jusqu&#39;à présent (par exemp...

La mesure de haute précision (mieux que 100 ppm / unité de masse atomique) zinc composition en isotopes stables n&#39;a été possible pendant environ 15 ans grâce au développement de multi-capteurs plasma source spectromètres de masse et a depuis été essentiellement appliquée dans la Terre et des sciences planétaires. Les applications dans le domaine médical sont nouveaux et ont un fort potentiel en tant que biomarqueurs pour les maladies qui modifient le métabolisme du zinc (par exemple, la maladie d&#39;Alzheimer). Cet article présente une méthode pour mesurer avec une grande précision les ratios des isotopes stables naturels de zinc dans divers organes de la souris. La même chose pourrait être applicable à des échantillons humains. Le procédé comprend la dissolution des organes, la purification chimique de zinc par rapport au reste des atomes, et ensuite l&#39;analyse du rapport isotopique sur un spectromètre de masse. La qualité des mesures isotopiques de Zn est tributaire de la qualité de la purification chimique (pureté de Zn, faible échantillon viergeARED à la quantité de Zn présent dans l&#39;échantillon, le rendement chimique élevée de la procédure) et sur le contrôle de la polarisation instrumentale. La grande pureté de la fraction Zn finale est nécessaire pour enlever les deux interférences isobares et les interférences non isobarique qui créent un effet de matrice. Nucléides isobariques créent des interférences directes (par exemple, 64 Ni). Des interférences isobariques non génèrent l&#39;effet dit &quot;matrice&quot; et modifier la précision des mesures d&#39;analyse en modifiant l&#39;état de l&#39;ionisation par rapport à la norme de zinc pur à laquelle les échantillons sont comparés à une. Un faible vide (&lt;10 ng) indique qu&#39;il n&#39;y a aucune contamination des échantillons par Zn externe qui biaiserait de la composition isotopique mesurée. Comme isotopes Zn peuvent être fractionnés au cours de la Chromatographie d&#39;échange d&#39;ions 2, la collection de tous les atomes de Zn assure qu&#39;aucun fractionnement isotopique se produit, ce qui implique que le procédé chimique doit avoir un rendement complet. Enfin, la correction du fractionnement isotopique instrumentale pendant la mesure de spectrométrie de masse se fait via la méthode &quot;de bracketing standard&quot;. Par conséquent, les principales difficultés pour obtenir des mesures précises sont le contrôle de la contamination externe (c.-bas blanc), la production d&#39;une purification chimique de plein rendement qui est propre de tous les autres atomes ou de molécules, et la correction du fractionnement isotopique instrumentale sur le spectromètre de masse. Dans cet article, nous allons décrire notre protocole analytique pour séparer Zn à partir d&#39;organes de la souris ainsi que les mesures de spectrométrie de masse. L&#39;extraction se fait en utilisant une faible quantité d&#39;acides dilués (HBr / HNO 3 de médias) sur les micro-colonnes (0,5 pi et 0,1 pi) de résine échangeuse d&#39;anions. Il dispose d&#39;un plein rendement et les mesures ont une reproductibilité externe supérieure à 50 ppm sur le rapport Zn 66/64 Zn. Un autre avantage de la méthod est qu&#39;il est très rapide. La méthode est donc très bien adaptée aux sciences médicales, dans lesquels on a besoin d&#39;analyser un grand nombre d&#39;échantillons par rapport aux géosciences, où ces méthodes analytiques ont été développés.

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			<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>
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		<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>
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		<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>
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high precision zinc isotopic measurements applied to mouse organs

Nous présentons une procédure pour mesurer avec des ratios d&#39;isotopes de zinc de haute précision dans les organes de souris. Le zinc est composé de cinq isotopes stables (64 Zn, 66 Zn, 67 Zn, Zn 68 et 70 Zn) qui sont fractionnés naturellement entre les organes de souris. Nous montrons d&#39;abord comment dissoudre les différents organes afin de libérer les atomes de Zn; cette étape est réalisée par un mélange de HNO 3 et H 2 O 2. Nous purifions alors les atomes de zinc de tous les autres éléments, notamment des interférences isobariques (par exemple, NI), par chromatographie échangeuse d&#39;anions dans un / HNO moyenne diluée de HBr 3. Ces deux premières étapes sont effectuées dans un laboratoire propre à l&#39;aide de produits chimiques de haute pureté. Enfin, les rapports isotopiques sont mesurées en utilisant un multi-collecteur à couplage inductif plasma spectromètre de masse, en basse résolution. Les échantillons sont injectés en utilisant une chambre de pulvérisation et le fractionnement isotopique induite par le spectromètre de masse est corrected en comparant le rapport des échantillons pour le rapport d&#39;une norme (technique de bracketing standard). Cette procédure typique pleine produit un rapport isotopique avec un 50 ppm (2 sd) reproductibilité.

Dans 1,5 N HBr, les principales espèces de zinc (ZnBr3-) de forme des complexes très forts avec la résine échangeuse d&#39;anions, tandis que la plupart des autres éléments ne interagissent avec la résine. Le zinc est récupéré puis en changeant le milieu de HNO 3 dilué, en changeant la spéciation du Zn à Zn 2+ qui est libéré à partir de la 6,7 de résine. les rapports isotopiques sont en général exprimés en parties par mille déviations par...

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.

Des mesures de haute précision Zinc isotopiques appliquées aux organes de souris

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 ...

high-precision-zinc-isotopic-measurements-applied-to-mouse-organs

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

Vidéo: 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.

Haute pression portable Sapphire pour les mesures de phase équilibres de CO<sub&gt; 2</sub&gt; / / Water Systems organiques

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

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Chimie

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.

La vitesse de refroidissement à charge Dimensions Ellipsométrie à déterminer la dynamique de Thin Films vitreux

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.

Immunocoloration phospho-épitopes dans ciliées organes de Mont entiers embryons de poissons zèbres

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.

Caractérisation, Quantification et spécifiques composé isotopiques Analyse des pyrogénée carbone Utilisation Benzène Acides polycarboxyliques (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.

Aérosol-assisted Chemical Vapor Deposition de Structures d’oxyde métallique : tiges d’oxyde de Zinc

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.

Caractérisation physique à haute résolution des nanoparticules métalliques uniques

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.

Effet isotopique dans le processus de transfert double de proton du porphycène étudié par la méthode améliorée de QM/MM

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.

Multiplexage automatisé de l’échantillon à l’aide de l’étiquetage isotopique combiné des précurseurs et du marquage isobarique (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.

Électrodes de batterie zinc-éponge qui suppriment les dendrites

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).

Suivi de position atomique picomètre-précision par microscopie électronique

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