Gli autori ringraziano il sostegno finanziario da parte della Labex-Imust.

1. Preparazione del campione biologico Tutti gli esperimenti descritti in questo studio sono stati approvati dal Comitato cura degli animali ed uso del CECCAPP (Lione, Francia) (autorizzazione # LYONSUD_2012_004), e gli esperimenti sono stati effettuati sotto la supervisione di persone autorizzate (L. Sancey, DDPP autorizzazione # 38 05 32). <ol><li> Aggiungere 1 ml di H 2 O a 100 pmol di nanoparticelle a base di gadolinio (Gd), attendere 15 min, e aggiungere 20 ml di HEPES 50 mM, NaCl 1,325 M, CaCl 2 20 mM a 100 ml di H 2 O e 80 microlitri la soluzione primaria di nanoparticelle a base di Gd per ottenere una soluzione di 200 ml a 40 mm pronti per l&#39;iniezione (Città: Villeurbanne, in laboratorio). </li><li> Iniettare la soluzione di nanoparticelle a base di Gd 200 ml per via endovenosa in anestetizzati tumore roditori (Città: Lyon Sud (Oullins), a 15 km da laboratorio). </li><li> 1-24 ore dopo l&#39;iniezione, i topi sacrificare und mettere i campioni biologici in isopentano raffreddato con azoto liquido. Conservare i campioni a - 80 ° C (Città: Lyon Sud (Oullins), a 15 km dal laboratorio). </li><li> Tagliate il campione (Città: solitamente Grenoble, a 100 km dal laboratorio; cercherò di avere un accesso a Lione Sud) in 100 slides micron di spessore e mettere le diapositive biologiche su piatti di plastica specifici (piatto di Petri). Conservare a -80 ° C. Nota: i piatti di plastica sono fondamentalmente un campione di polimero molto puro. Essi sono utilizzati per evitare interferenze con gli elementi contenuti nel tessuto. </li></ol> 2. Preparazione del campione per la calibrazione <ol><li> Preparare flaconi con dosi crescenti di nanoparticelle basato Gd in acqua (0 nM, 100 nM, 500 nM, 1 mM, 5 mM, 10 mM, 50 mM, 100 mM, 500 mM, 1 mM e 5 mM). </li><li> Mettere un 5 ml-drop di ogni soluzione regolarmente distanziate di 3 mm sulla piastra di Petri. </li><li> Asciutto a temperatura ambiente per 20 minuti. </li></ol>3. LIBS Experiment <ol><li> Inizializzazione Setup LIBS <ol><li> Impostazioni Laser. Dopo l&#39;accensione degli strumenti, attendere 10-20 minuti per la stabilizzazione di energia laser a impulsi e il raffreddamento della macchina fotografica ICCD a -20 ° C. Regolare l&#39;energia dell&#39;impulso con l&#39;attenuatore. Nota: I parametri ottimali laser per tessuti di mappatura sono 5 nsec durata dell&#39;impulso, 1.064 nm di lunghezza d&#39;onda, e l&#39;energia di impulso di circa 4 mJ. Il laser utilizzato è un tipico Nd: YAG laser nanosecondo. </li><li> LIBS Impostazioni. Impostare la posizione di focalizzazione laser (rispetto alla superficie del campione) per ottenere il diametro più piccolo cratere (circa 50 micron o meno). Nota: Questo corrisponde ad una focalizzazione dell&#39;impulso laser 100 micron sotto la superficie del campione. </li><li> Impostazioni spettrometro. Utilizzare lo spettrometro Czerny-Turner combinato con un 1.200 linee / mm reticolo e un elevato temporale fotocamera a risoluzione ICCD. Controllare tutti questi dispositivi da computer. Impostare il valore fessura di ingresso a 40 micron. Impostare l&#39;intervallo spettrale reGARDING l&#39;elemento da analizzare. Utilizzare l&#39;intervallo spettrale copre 325-355 nm per rivelare Gd con alta sensibilità, così come Na, Ca e Cu. Impostare i parametri ICCD con un ritardo di 300 nsec, un cancello di 2 msec, e un guadagno di 200. </li></ol></li><li> Mapping di misura <ol><li> Collocare il campione biologico sul supporto del campione LIBS motorizzato. </li><li> Regolare l&#39;altezza del campione secondo la posizione del fuoco del laser. </li><li> Prendete un alta risoluzione foto della fetta del campione. </li><li> Impostare il modulo mappatura del software di acquisizione LIBS effettuare una mappa con tipicamente 100 x 100 punti di misura distanziati da una risoluzione di circa 100 pm. </li><li> Avviare l&#39;acquisizione. Da questo punto di automatizzare tutto; il movimento sequenza così come la registrazione dello spettro e risparmio. 40 min sono necessari per una mappatura di 10.000 punti (equivalente a 1 cm 2 per risoluzione di 100 micron). Raggruppare tutti gli spettri registrati in uno stesso file. </li><li> Quando finished, scattare una seconda foto della fetta del campione </li></ol></li><li> Misurazione Calibrazione </li></ol> Con gli stessi parametri sperimentali, misurare i campioni di calibrazione (per i dettagli di preparazione, vedere paragrafo 2). Eseguire una mappa o record di 25 spettri (ottenuto da siti di misura nella parte centro della goccia) in ciascuna delle gocce di taratura. 4 LIBS Spectrum Analysis:. Costruire delle immagini chimici <ol><li> Registrare tutti gli spettri LIBS dalla mappatura del tessuto e caricarli nel software di analisi LIBS. Sottrarre la linea di base per ogni spettro e costruire le immagini chimici con scala di intensità relativa utilizzando un colore falso. Nota: Un algoritmo recupera specifici intensità di linea, come Gd, Cu, Na, o Ca. </li><li> Eseguire la stessa operazione sul spettri misurati dal campione calibrato per consentire il calcolo curve di calibrazione (relazione tra intensità e concentrazione) e costruire aqmappa uantitative o immagine per Gd (o altro elemento di interesse). </li><li> Applicare i trattamenti adeguati alle immagini chimici, come interpolazione o levigatura. Salvare l&#39;intensità o la concentrazione mappe in formato immagine (bitmap). </li></ol>

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S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantifying+trace+elements+in+individual+aquatic+protist+cells+with+a+synchrotron+X-ray+fluorescence+microprobe.">Quantifying trace elements in individual aquatic protist cells with a synchrotron X-ray fluorescence microprobe.</a> Analytical chemistry. 75, 3806-3816 (2003).</li><li>Guerquin-Kern, J. L., Wu, T. D., Quintana, C., Croisy, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress+in+analytical+imaging+of+the+cell+by+dynamic+secondary+ion+mass+spectrometry+(SIMS+microscopy).">Progress in analytical imaging of the cell by dynamic secondary ion mass spectrometry (SIMS microscopy).</a> Biochimica et biophysica acta. 1724, 228-238 (2005).</li><li>Binet, M. R., Ma, R., McLeod, C. W., Poole, R. 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Gli autori non hanno nulla da rivelare.

Applicato al campione biologico, questa tecnica consente di imaging chimica, cioè la mappatura e quantificazione, di Do e Si iniettati da nanoparticelle a base di Gd in diversi organi. Dalle principali impostazioni critiche, il controllo delle proprietà del laser (lunghezza d&#39;onda, energia dell&#39;impulso, focalizzazione e stabilità) è fondamentale per una ablazione del tessuto preciso e fine (cioè risoluzione mapping), nonché per la sensibilità. Lavorare ad alta energia offre una migliore ...

L&#39;ampio sviluppo di nanoparticelle per applicazioni biologiche sollecitato il parallelo miglioramento delle tecniche analitiche per la loro quantificazione e di imaging in campioni biologici. Solitamente la rilevazione e la mappatura delle nanoparticelle in organi sono fatti da fluorescenza o microscopia confocale. Sfortunatamente questi metodi richiedono l&#39;etichettatura delle nanoparticelle da un colorante vicino infrarosso che può modificare la biodistribuzione delle nanoparticelle, in particolare per le piccolissime nanoparticelle per le sue proprietà idrofobiche. La rilevazione delle nanoparticelle etichettati, e soprattutto le piccole nanoparticelle (dimensioni &lt;10 nm), potrebbe quindi interferire con la loro distribuzione biologica l&#39;intera scala di corpo, ma anche a livello di tessuti e cellule. Lo sviluppo di nuovi dispositivi in ​​grado di rilevare le nanoparticelle senza etichettatura offre nuove possibilità per lo studio del loro comportamento e cinetica. Inoltre, il ruolo di oligoelementi, quali ferro e rame nel cervello Malattie di unmalattie neurodegenerative come l&#39;Alzheimer d 1, Menkes 2,3, o 4 Wilson suggeriscono l&#39;interesse di studiare e localizzare questi elementi nei tessuti. Varie tecniche sono state usate per fornire la mappatura microanalisi elementare o di materiali diversi. Nel loro articolo recensione pubblicata nel 2006, R. Lobinski et al. Ha fornito una panoramica delle tecniche disponibili standard per microanalisi elementare in ambiente biologico, uno degli ambienti più difficili per le scienze analitiche 5. Microsonda elettronica, che consiste di energia dispersiva microanalisi a raggi X in un microscopio elettronico a trasmissione, può essere applicato a numerosi studi se la concentrazione dell&#39;elemento è sufficiente (&gt; 100-1.000 mg / g). Per raggiungere limiti di rivelazione inferiori, sono state utilizzate le seguenti tecniche: <ul><li> microsonda fascio ionico usando particelle indotta da X-ray Emission μ-PIXE (1-10 mg / g) 6 </li><li> synchrotron microanalisi radiazione μ-SXRF (0,1-1 mg / g) 7 </li><li> spettrometria di massa di ioni secondari SIMS (0.1 mg / g) 8 </li><li> ablazione laser accoppiato induttivamente spettrometria di massa LA-ICP-MS (fino a 0,01 mg / g) 9,10 </li></ul> Le tecniche sopra citate forniscono risoluzione micrometrica come mostrato nella Tabella 1 estratto da Lobinski et al. Ricostruzione 3D delle indagini 2D di serie potrebbe essere proposto anche per la ricostruzione dei tessuti più profondi 11. Tuttavia, tutti i dispositivi e sistemi richiedono entrambi professionisti qualificati, moderati da attrezzature altamente costose ed esperimenti di lunga durata (in genere più di 4 ore per un 100 micron x 100 micron per μ-SXRF di 10 mm x 10 mm per LA-ICP-MS ) 12. Complessivamente, questi requisiti rendono microanalisi elementare molto limitazione e incompatibile con i sistemi di imaging ottico convenzionale,microscopia a fluorescenza o microscopia non lineare. Un altro punto che si può menzionare qui è che la capacità di misura quantitativa è ancora abbastanza limitata e dipende dalla disponibilità di standard di laboratorio accoppiata alla matrice. L&#39;ulteriore generalizzazione dell&#39;uso di microanalisi elementare nei processi industriali, la geologia, la biologia e altri domini di applicazioni apporterà notevoli progressi concettuali e tecnologiche. Lo scopo della presente manoscritto è quello di proporre soluzioni per la mappatura elementare quantitativa (o microanalisi elementare) nei tessuti biologici con una strumentazione tavolo pienamente compatibile con microscopia ottica convenzionale. Il nostro approccio è basato sulla spettroscopia ripartizione indotta da laser (tecnologia LIBS). In LIBS, un impulso laser viene focalizzato sul campione di interesse per creare la composizione e la scintilla del materiale. La radiazione emessa atomico nel plasma viene successivamente analizzato da uno spettrometro e il elementariLe concentrazioni TAL possono essere recuperati con le misure di calibrazione effettuate in anticipo 13,14. I vantaggi di LIBS includono sensibilità (mcg / g per quasi tutti gli elementi), compattezza, preparazione molto semplice campione, assenza di contatto con il campione, risposta istantanea e localizzata precisamente (micro) analisi di superficie. Tuttavia, l&#39;applicazione dell&#39;imaging chimico tessuto rimane difficile dall&#39;inizio della ablazione laser del tessuto deve essere finemente controllata effettuare mappe con elevata risoluzione spaziale e la sensibilità nell&#39;intervallo mcg / g 15,16. Con tale soluzione, non è richiesta l&#39;aggiunzione di rivelatori o agenti di etichettatura, che permette di rilevare elementi inorganici direttamente nel loro ambiente nativo nei tessuti biologici. Lo strumento LIBS sviluppato nel nostro laboratorio offre una risoluzione corrente inferiore a 100 micron, con una sensibilità stimata per Gd inferiore a 35 mg / g, pari a 0,1 mM 16, che consentela mappatura di grandi campioni (&gt; 1 cm 2) in 30 min. Inoltre, il software casalingo facilita l&#39;acquisizione e lo sfruttamento dei dati. Questo strumento è utilizzato per rilevare, carta, e quantificare la distribuzione tissutale di gadolinio nanoparticelle basate (Gd) 17 - 18 nei reni e campioni tumorali da piccoli animali, da 1 a 24 ore dopo l&#39;iniezione endovenosa di particelle (dimensione &lt;5 nm) . Elementi inorganici, che sono intrinsecamente contenute in un tessuto biologico, come Fe, Ca, Na, e P, sono stati rilevati e ripreso.

<table border="0" cellpadding="0" cellspacing="0" width="747">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Laser nanosecond Nd:YAG</td>
			<td style="width:129px;">Quantel</td>
			<td style="width:119px;">Brillant</td>
			<td style="width:283px;">5ns pulse witdh, wavelength 1064 nm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Spectrometer</td>
			<td>Andor Technology</td>
			<td>Shamrock 303</td>
			<td>with 1200 l/mm blazed at 300 nm grating</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Detector ICCD</td>
			<td>Andor Technology</td>
			<td style="width:119px;">Istar</td>
			<td>2 ns temporal resolution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">LIBS Unit</td>
			<td style="width:129px;">ILM</td>
			<td style="width:119px;"></td>
			<td>Homemade Instrumentation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:129px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Gd-based nanoparticles</td>
			<td style="width:129px;">Nano-H</td>
			<td style="width:119px;"></td>
			<td>particles</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HEPES</td>
			<td style="width:129px;">Sigma-Aldrich</td>
			<td style="width:119px;">H4034</td>
			<td>for particle&#39;s dilution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CaCl2</td>
			<td style="width:129px;">Sigma-Aldrich</td>
			<td style="width:119px;">21108</td>
			<td>for particle&#39;s dilution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">NaCl</td>
			<td style="width:129px;">Sigma-Aldrich</td>
			<td style="width:119px;">S5886</td>
			<td>for particle&#39;s dilution</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">mice</td>
			<td style="width:129px;">Charles River</td>
			<td style="width:119px;">depending of animal breeding</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">isoflurane</td>
			<td style="width:129px;">Coveto / Virbac</td>
			<td style="width:119px;"></td>
			<td>for anaesthesia - Isofluranum</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">isopentane</td>
			<td style="width:129px;">Sigma-Aldrich</td>
			<td style="width:119px;">59060</td>
			<td>to froze the sample&#160; slowly</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">liquide nitrogen</td>
			<td style="width:129px;">Air Liquide</td>
			<td style="width:119px;"></td>
			<td>to cool down the isopentane</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">cryostat</td>
			<td style="width:129px;">Leica</td>
			<td style="width:119px;">CM-3050S</td>
			<td>to slide the samples</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">petri dishes</td>
			<td style="width:129px;">Dutscher</td>
			<td style="width:119px;">353004</td>
			<td>to stick the sample</td>
		</tr>
	</tbody>
</table>

laser-induced breakdown spectroscopy: a new approach for nanoparticle's mapping and quantification in organ tissue

Spettroscopia di emissione di plasma indotto da laser è stato applicato ad analisi elementare di campioni biologici. Spettroscopia ripartizione laser-indotta (LIBS) eseguita su sezioni sottili di tessuti roditori: reni e tumorali, consente il rilevamento di elementi inorganici come (i) Na, Ca, Cu, Mg, P, Fe e, naturalmente presenti nel corpo e (ii) Si e Gd, rilevati dopo l&#39;iniezione di nanoparticelle a base di gadolinio. Gli animali sono stati sacrificati da 1 a 24 ore dopo l&#39;iniezione endovenosa di particelle. Una scansione bidimensionale del campione, effettuata utilizzando un micrometrica 3D-stadio motorizzato, ha permesso il raggio laser infrarosso esplorare la superficie con una risoluzione laterale di 100 μ m. Immagini chimica quantitativa di elemento Gd all&#39;interno dell&#39;organo sono stati ottenuti con sensibilità sub-mM. LIBS offre un metodo semplice e robusto per studiare la distribuzione di materiali inorganici senza labeli specificong. Inoltre, la compatibilità della configurazione con microscopia ottica standard sottolinea il suo potenziale di fornire immagini multiple dello stesso tessuto biologico con differenti tipi di risposte: elementari, molecolari o cellulari.

Come mostrato in figura 1, il fascio di un laser Nd: YAG nella lunghezza d&#39;onda fondamentale di 1.064 nm è concentrata verticalmente sulla fetta di tessuto da una lente di quarzo di 50 mm di distanza focale. L&#39;energia di impulso è stato di 4 mJ e la frequenza di ripetizione 10 Hz. Al fine di evitare la generazione di plasma in aria, il fascio laser è focalizzato circa 100 micron sotto la superficie del campione. Nessuna plasma ad aria è stato osservato in questa condizione. Durante gli esper...

Watch this Scientific Journal Video about Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue at JoVE.com

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle&#039;s Mapping and Quantification in Organ Tissue

Spettroscopia laser ripartizione indotta eseguita su organi sottile e tessuto tumorale rilevato con successo elementi naturali e gadolinio artificialmente iniettato (Gd), emessi da nanoparticelle a base di Gd. Immagini di elementi chimici raggiunto una risoluzione di 100 micron e sensibilità quantitativa sub-mM. La compatibilità del setup con la microscopia ottica standard sottolinea la sua capacità di fornire immagini multiple di uno stesso tessuto biologico.

Spettroscopia Laser-Induced Breakdown: un nuovo approccio per la mappatura di nanoparticelle e la quantificazione in Tissue Organ

Emission spectroscopy of laser-induced plasma was applied to elemental analysis of biological samples. Laser-induced breakdown spectroscopy (LIBS) ...

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Research

JoVE Journal

Engineering

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue

13.6K Views.  CNRS - Université Lyon 1.  Spettroscopia laser ripartizione indotta eseguita su organi sottile e tessuto tumorale rilevato con successo elementi naturali e gadolinio artificialmente iniettato (Gd), emessi da nanoparticelle a base di Gd. Immagini di elementi chimici raggiunto una risoluzione di 100 micron e sensibilità quantitativa sub-mM. La compatibilità del setup con la microscopia ottica standard sottolinea la sua capacità di fornire immagini multiple di uno stesso tessuto biologico. 

Video: Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue

Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

The physical properties of a material are defined by its electronic structure. Electrons in solids are characterized by energy (&omega;) and momentum (k) and the probability to find them in a particular state with given &omega; and k is described by the spectral function A(k, &omega;). This function can be directly measured in an experiment based on the well-known photoelectric effect, for the explanation of which Albert Einstein received the Nobel Prize back in 1921. In the photoelectric effect the light shone on a surface ejects electrons from the material. According to Einstein, energy conservation allows one to determine the energy of an electron inside the sample, provided the energy of the light photon and kinetic energy of the outgoing photoelectron are known. Momentum conservation makes it also possible to estimate k relating it to the momentum of the photoelectron by measuring the angle at which the photoelectron left the surface. The modern version of this technique is called Angle-Resolved Photoemission Spectroscopy (ARPES) and exploits both conservation laws in order to determine the electronic structure, i.e. energy and momentum of electrons inside the solid. In order to resolve the details crucial for understanding the topical problems of condensed matter physics, three quantities need to be minimized: uncertainty* in photon energy, uncertainty in kinetic energy of photoelectrons and temperature of the sample.
In our approach we combine three recent achievements in the field of synchrotron radiation, surface science and cryogenics. We use synchrotron radiation with tunable photon energy contributing an uncertainty of the order of 1 meV, an electron energy analyzer which detects the kinetic energies with a precision of the order of 1 meV and a He3 cryostat which allows us to keep the temperature of the sample below 1 K. We discuss the exemplary results obtained on single crystals of Sr2RuO4 and some other materials. The electronic structure of this material can be determined with an unprecedented clarity.

The overall goal of this method is to determine the low-energy electronic structure of solids at ultra-low temperatures using Angle-Resolved Photoemission Spectroscopy with synchrotron radiation.

Angolo-spettroscopia di fotoemissione risolta A ultra-basse temperature

The physical properties of a material are defined by its  electronic structure. Electrons in solids are characterized by energy (&omega;)  and momentum ...

Ricerca

Ingegneria

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

Probing e mapping superfici di elettrodo nelle celle di combustibile ad ossidi solidi

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

Scanning-probe Single-electron Capacitance Spectroscopy

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the electronic quantum structure of small systems - including individual atomic dopants in semiconductors. Here we present a capacitance-based method, known as Subsurface Charge Accumulation (SCA) imaging, which is capable of resolving single-electron charging while achieving sufficient spatial resolution to image individual atomic dopants. The use of a capacitance technique enables observation of subsurface features, such as dopants buried many nanometers beneath the surface of a semiconductor material1,2,3. In principle, this technique can be applied to any system to resolve electron motion below an insulating surface.
As in other electric-field-sensitive scanned-probe techniques4, the lateral spatial resolution of the measurement depends in part on the radius of curvature of the probe tip. Using tips with a small radius of curvature can enable spatial resolution of a few tens of nanometers. This fine spatial resolution allows investigations of small numbers (down to one) of subsurface dopants1,2. The charge resolution depends greatly on the sensitivity of the charge detection circuitry; using high electron mobility transistors (HEMT) in such circuits at cryogenic temperatures enables a sensitivity of approximately 0.01 electrons/Hz&frac12; at 0.3 K 5.

Scanning-probe single-electron capacitance spectroscopy facilitates the study of single-electron motion in localized subsurface regions. A sensitive charge-detection circuit is incorporated into a cryogenic scanning probe microscope to investigate small systems of dopant atoms beneath the surface of semiconductor samples.

Scansione-sonda a singolo elettrone Capacità Spettroscopia

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the ...

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement is used. Here we operate a Nd:YAG laser at a frequency of 10 Hz at the fundamental wavelength of 1,064 nm. The 14 nsec pulses with anenergy of 190 mJ/pulse are focused to a 50 &#181;m spot size to generate a plasma from optical breakdown or laser ablation in air. The microplasma is imaged onto the entrance slit of a 0.6 m spectrometer, and spectra are recorded using an 1,800 grooves/mm grating an intensified linear diode array and optical multichannel analyzer (OMA) or an ICCD. Of interest are Stark-broadened atomic lines of the hydrogen Balmer series to infer electron density. We also elaborate on temperature measurements from diatomic emission spectra of aluminum monoxide (AlO), carbon (C2), cyanogen (CN), and titanium monoxide (TiO).
The experimental procedures include wavelength and sensitivity calibrations. Analysis of the recorded molecular spectra is accomplished by the fitting of data with tabulated line strengths. Furthermore, Monte-Carlo type simulations are performed to estimate the error margins. Time-resolved measurements are essential for the transient plasma commonly encountered in LIBS.

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

Time-resolved atomic and diatomic molecular species are measured using LIBS. The spectra are collected at various time delays following the generation of optical breakdown plasma with Nd:YAG laser radiation&#160;and are analyzed to infer electron density and temperature.

Misura e Analisi di idrogeno atomico e molecolare Diatomic AlO, C<sub&gt; 2</sub&gt;, CN, e TiO Spectra Following Laser-Induced Breakdown ottico

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement ...

Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy

Monitoring the dynamics of protonation and protein backbone conformation changes during the function of a protein is an essential step towards understanding its mechanism. Protonation and conformational changes affect the vibration pattern of amino acid side chains and of the peptide bond, respectively, both of which can be probed by infrared (IR) difference spectroscopy. For proteins whose function can be repetitively and reproducibly triggered by light, it is possible to obtain infrared difference spectra with (sub)microsecond resolution over a broad spectral range using the step-scan Fourier transform infrared technique. With ~102-103 repetitions of the photoreaction, the minimum number to complete a scan at reasonable spectral resolution and bandwidth, the noise level in the absorption difference spectra can be as low as ~10-4, sufficient to follow the kinetics of protonation changes from a single amino acid. Lower noise levels can be accomplished by more data averaging and/or mathematical processing. The amount of protein required for optimal results is between 5-100 &#181;g, depending on the sampling technique used. Regarding additional requirements, the protein needs to be first concentrated in a low ionic strength buffer and then dried to form a film. The protein film is hydrated prior to the experiment, either with little droplets of water or under controlled atmospheric humidity. The attained hydration level (g of water / g of protein) is gauged from an IR absorption spectrum. To showcase the technique, we studied the photocycle of the light-driven proton-pump bacteriorhodopsin in its native purple membrane environment, and of the light-gated ion channel channelrhodopsin-2 solubilized in detergent.

Key steps of protein function, in particular backbone conformational changes and proton transfer reactions, often take place in the microsecond to millisecond time scale. These dynamical processes can be studied by time-resolved step-scan Fourier-transform infrared spectroscopy, in particular for proteins whose function is triggered by light.

Proton Transfer e conformazione proteica Dynamics in proteine ​​fotosensibili da Time-risolto Step-scan trasformata di Fourier Infrared Spectroscopy

Monitoring the dynamics of protonation and protein backbone conformation changes during the function of a protein is an essential step towards ...

In Situ Time-dependent Dielectric Breakdown in the Transmission Electron Microscope: A Possibility to Understand the Failure Mechanism in Microelectronic Devices

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. The aggressive scaling of feature sizes, both on devices and interconnects, leads to serious challenges to ensure the required product reliability. Standard reliability tests and post-mortem failure analysis provide only limited information about the physics of failure mechanisms and degradation kinetics. Therefore it is necessary to develop new experimental approaches and procedures to study the TDDB failure mechanisms and degradation kinetics in particular. In this paper, an in situ experimental methodology in the transmission electron microscope (TEM) is demonstrated to investigate the TDDB degradation and failure mechanisms in Cu/ULK interconnect stacks. High quality imaging and chemical analysis are used to study the kinetic process. The in situ electrical test is integrated into the TEM to provide an elevated electrical field to the dielectrics. Electron tomography is utilized to characterize the directed Cu diffusion in the insulating dielectrics. This experimental procedure opens a possibility to study the failure mechanism in interconnect stacks of microelectronic products, and it could also be extended to other structures in active devices.

In Situ Time-dependent Dielectric Breakdown in the Transmission Electron Microscope: A Possibility to Understand the Failure Mechanism in Microelectronic Devices

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. This paper demonstrates the procedure of an in situ TDDB experiment in the transmission electron microscope, which opens a possibility to study the failure mechanism in microelectronic products.

In Situ in funzione del tempo di rottura dielettrico nel Transmission Electron Microscope: A Con possibilità di capire il meccanismo Fallimento in dispositivi microelettronici

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. ...

Laser-induced Forward Transfer for Flip-chip Packaging of Single Dies

Flip-chip (FC) packaging is a key technology for realizing high performance, ultra-miniaturized and high-density circuits in the micro-electronics industry. In this technique the chip and/or the substrate is bumped and the two are bonded via these conductive bumps. Many bumping techniques have been developed and intensively investigated since the introduction of the FC technology in 19601 such as stencil printing, stud bumping, evaporation and electroless/electroplating2. Despite the progress that these methods have made they all suffer from one or more than one drawbacks that need to be addressed such as cost, complex processing steps, high processing temperatures, manufacturing time and most importantly the lack of flexibility. In this paper, we demonstrate a simple and cost-effective laser-based bump forming technique known as Laser-induced Forward Transfer (LIFT)3. Using the LIFT technique a wide range of bump materials can be printed in a single-step with great flexibility, high speed and accuracy at RT. In addition, LIFT enables the bumping and bonding down to chip-scale, which is critical for fabricating ultra-miniature circuitry.

We demonstrate the use of the Laser-induced Forward Transfer (LIFT) technique for flip-chip assembly of optoelectronic components. This approach provides a simple, cost-effective, low-temperature, fast and flexible solution for fine-pitch bumping and bonding on chip-scale for achieving high-density circuits for optoelectronic applications.

Laser-indotta Transfer Forward per Flip-chip Packaging di Dies Singolo

Flip-chip (FC) packaging is a key technology for realizing high performance, ultra-miniaturized and high-density circuits in the micro-electronics ...

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

Tomografia a dispersione di energia dei raggi X per il 3D Elemental mappatura delle nanoparticelle individuali

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Rilevamento e recupero di palladio, oro e metalli di cobalto dalla miniera urbana Utilizzando novelli Sensori / Adsorbenti designate con nanoscala Wagon a forma di ruote pori

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Blast Quantification Using Hopkinson Pressure Bars

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures up to many hundreds of megapascals. In this respect the simplicity of the Hopkinson pressure bar has a major advantage in that while the measurement end of the Hopkinson bar can endure and be exposed to harsh conditions, the strain gauge mounted to the bar can be affixed some distance away. This allows protective housings to be utilized which protect the strain gauge but do not interfere with the measurement acquisition. The use of an array of pressure bars allows the pressure-time histories at discrete known points to be measured. This article also describes the interpolation routine used to derive pressure-time histories at un-instrumented locations on the plane of interest. Currently the technique has been used to measure loading from high explosives in free air and buried shallowly in various soils.

This protocol details the use of Hopkinson pressure bars to measure reflected blast loading from near-field explosive events. It is capable of interpolating a pressure-time history at any point on a reflective boundary and as such can be used to fully characterize the spatial and temporal variations in loading produced.

Blast Quantificazione Utilizzando Hopkinson Pressure Bar

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures ...