Gli autori riconoscono un finanziamento da parte del Ministero della Pubblica Istruzione di Singapore Livello 2 Fondo di ricerca (progetto MOE2013-T2-2-002) per questo progetto.

1. Procedura di preparazione per il 1,3,5-Triphenylbenzene (1) <ol><li> Mettere una miscela di acetofenone (4,0 g, 33,3 mmoli) e 100 ml di etanolo assoluto in tre collo del matraccio da 250 ml a fondo tondo dotato di agitatore magnetico, condensatore a riflusso, ingresso per azoto, gorgogliatore, imbuto gocciolatore e termometro. Aggiungere tetracloruro di silicio (11,9 g, 8,0 ml, 70,2 mmoli, 2,1 eq.) Alla miscela in una porzione a 0 ° C sotto azoto usando l&#39;imbuto. </li><li> Osservare l&#39;evoluzione di cloruro di idrogeno gassoso per 10 min. Poi agitare la miscela di reazione a 40 ° C per 20 ore. </li><li> Raffreddare la miscela di reazione a 23 ° C e versare in 200 g di acqua mista a ghiaccio (rapporto 1: 1 di massa). </li><li> Estrarre la miscela risultante con diclorometano (2 x 100 ml) usando un imbuto di estrazione. </li><li> Lavare gli estratti riuniti una volta con soluzione satura di NaCl (100 ml), e secca su 15 g di anidro MgSO 4. Filtrare il liquido parte fuori e poi concentrarsi noizione un evaporatore rotante. </li><li> Purificare il prodotto mediante ricristallizzazione da etanolo (dissoluzione in quantità minima di etanolo seguita da evaporazione parziale del solvente, mantenendo a 6 ° C per una notte, e filtrazione rapida) per ottenere 2,2 g (resa 63%) di 1,3,5-triphenylbenzene (1) come cristalli di colore giallo pallido. Nota: 1 H-NMR (400 MHz, CDCl 3):. Δ = 7.41 (m, 3H), 7,50 (m, 6H), 7,72 (d, 6H, J = 7.33Hz), 7,80 (s, 3H) 13 C-NMR (400 MHz, CDCl 3): δ = 125.21, 127.39, 127.57, 128.88, 141.18, 142.38. </li></ol> 2. Lises preparati con 1,3,5-Triphenylbenzene <ol><li> Preparazione di 1,3,5-triphenylbenzene a base Lises NOTA: 1,3,5-triphenylbenzene utilizzato in questo documento è stato sintetizzato secondo il procedimento sopra descritto. I 1,3,5-triphenylbenzene Lises basati sono indicati con Li x TPB (THF) 24,7 dove x denota la Li: rapporto molare PAH e TPB denota 1,3,5-triphenylbenzene. preparare Lix TPB (THF) 24,7 all&#39;interno di un vano portaoggetti argon-riempita a temperatura ambiente attraverso i seguenti passaggi: <ol><li> Misurate quantità ben definite di metallico Li, THF e TPB separatamente all&#39;interno del cassetto portaoggetti per raggiungere l&#39;obiettivo composizione molare Li x TPB (THF) 24,7 per x = 1, 2, 3, e 4. Usare 41,6 mg, 83,3 mg, 124.9 mg, 166,6 mg di Li per x = 1, 2, 3 e 4 rispettivamente. </li><li> Per ciascuno dei quattro campioni Lises da preparare, sciogliere 1,84 g di TPB in 12 ml di THF all&#39;interno quattro bottiglie di vetro separati per formare 12 ml di soluzione incolore di TPB (THF) 24,7 per ciascuna bottiglia. Utilizzare un M 1,3,5-triphenylbenzene 0,5 in tutte le soluzioni. </li><li> Aggiungere il metallico pesato Li sventa alle quattro bottiglie e sigillare le bottiglie con parafilm. </li><li> Mescolare la miscela in ogni notte flacone con un agitatore magnetico di vetro rivestite per garantire la completa dissoluzione del metallo Li. </li></ol></li><li> conducibilità Misure <ol><li> Portaresu tutte le misure di conducibilità utilizzando una sonda cella di conducibilità standard basato sulla tecnica a quattro elettrodi. Fissare la sonda cella di un metro. La sonda ha una funzione secondaria per misurare la temperatura della soluzione allo stesso tempo e visualizzare sia misure di conducibilità e temperatura. </li><li> Prima di effettuare misurazioni, calibrare lo strumento con 50 ml della soluzione standard di 0,01 M acquosa KCl forniti dal produttore della sonda di conducibilità al di fuori del cassetto portaoggetti. </li><li> Eseguire tutte le misure di conducibilità per Lises a base di 1,3,5-triphenylbenzene, Li x TPB (THF) 24,7 per x = 1, 2, 3, 4 all&#39;interno del cassetto portaoggetti. </li><li> Per ognuno di questi Lises, versare il campione in un breve cilindro di vetro e immergere la sonda nella soluzione. Registrare la misura di conducibilità per un periodo di una o due ore fino a ogni scheda campione ad una temperatura ambiente. Il tempo impiegato per ciascun campione per tornare a temperatura ambiente è ~ 1-2 hr. La sonda will rimanere immerse nel campione per tutta la durata della misura di conducibilità. </li></ol></li></ol> 3. corannulene <ol><li> Preparazione di Lises corannulene-based . NOTA: Il corannulene utilizzato in questo lavoro è stato sintetizzato presso la Scuola di Scienze Fisiche e Matematiche, NTU utilizzando una procedura di letteratura più fasi 9 Le Lises corannulene-based sono indicati con Li x Cor (THF) 247 dove x denota la Li: molare PAH rapporto e Cor denota il corannulene. Preparare Li x Cor (THF) 247 all&#39;interno di un vano portaoggetti argon-riempita a temperatura ambiente attraverso i seguenti passaggi: <ol><li> Misurate quantità ben definite di metallico Li, THF e Cor separatamente all&#39;interno del cassetto portaoggetti per ottenere la composizione di destinazione molare Li x Cor (THF) 247 per x = 1, 2, 3, 4 e 5. Uso 4.2 mg, 8,3 mg, 12,5 mg, 16,6 mg e 20,8 mg di Li per x = 1, 2, 3, 4 e 5, rispettivamente. </li><li> Next, per ciascuno dei Lises campioni cinque (x = 1, 2, 3, 4 e 5) da preparare, sciogliere 0,15 g di Cor in 12 ml di THF all&#39;interno cinque bottiglie di vetro separate per formare 12 ml di soluzione incolore di Cor (THF) 247 in ogni bottiglia. Utilizzare una concentrazione corannulene di 0,05 M). </li><li> Successivamente, aggiungere il metallico pesato Li sventa ai cinque bottiglie di Cor (THF) 247 e sigillare le bottiglie con parafilm. </li><li> Mescolare la miscela in ogni notte flacone con un agitatore magnetico di vetro rivestite per garantire la completa dissoluzione del litio metallico. </li></ol></li><li> conducibilità Misure <ol><li> Per conducibilità contro misure di temperatura, rimuovere ciascuna delle cinque bottiglie contenenti Li x Cor (THF) 247 per x = 1, 2, 3, 4 e 5 singolarmente dal vano portaoggetti, avvolgerlo con un ulteriore strato di para-pellicola ed immergerlo all&#39;interno di un contenitore di polistirolo isolante riempito di ghiaccio secco. NOTA: I campioni Lises non è venuto in contagire sia con l&#39;umidità o ossigeno mentre fuori il cassetto portaoggetti, perché le bottiglie sono state sigillate. </li><li> Raffreddare ogni bottiglia fino a circa 10 ° C mantenendo ogni bottiglia immersa nel ghiaccio secco per circa 30 minuti prima di essere trasferito nuovamente dentro il vano portaoggetti per misure di conducibilità. </li><li> Eliminare l&#39;anticamera del cassetto portaoggetti almeno 5 volte per ogni raffreddati campione per assicurarsi che nessuna traccia di acqua di condensa accompagnano la bottiglia di nuovo nel cassetto portaoggetti. </li><li> Simile al modo in cui conduttività rispetto misurazioni di temperatura sono stati raccolti per Lises naftalen-based campioni 1, misurare la conduttività del Li x Cor (THF) 247 (x = 1, 2, 3, 4, 5) per un periodo da uno a due ore fino ciascun campione restituiti alla temperatura ambiente. La sonda rimarrà immersa nel campione per tutta la durata della misura di conducibilità. </li></ol></li></ol>

<ol>
	<li>Tan, K. S., Yazami, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physical-Chemical+and+Electrochemical+Studies+of+the+Lithium+Naphthalenide+Anolyte.">Physical-Chemical and Electrochemical Studies of the Lithium Naphthalenide Anolyte.</a> Electrochim Acta. 180, 629-635 (2015).</li><li>Tan, K. S., Grimsdale, A. C., Yazami, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Characterisation+of+Biphenyl-Based+Lithium+Solvated+Electrons+Solutions.">Synthesis and Characterisation of Biphenyl-Based Lithium Solvated Electrons Solutions.</a> J Phys Chem B. 116, 9056-9060 (2012).</li><li>Rinaldi, A., Tan, K. S., Wijaya, O., Wang, Y., Yazami, R., Menictas, C., Skyllas-Kazacos, M., Lim, T. M., Hughes, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch.+11.">Ch. 11.</a> Advances in batteries for large- and medium-scale energy storage applications in power systems and electric vehicles. , (2014).</li><li>Wang, Y., Tan, K. S., Yazami, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Materials Challenges In Alternative &amp; Renewable Energy (MCARE 2014). , (2014).</li><li>Yazami, R., Tan, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> in 8th annual Li Battery Power. , (2012).</li><li>Yazami, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hybrid+Electrochemical+Generator+With+A+Soluble+Anode.">Hybrid Electrochemical Generator With A Soluble Anode.</a> US patent. , (2010).</li><li>Yazami, R., Tan, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid+Metal+Battery.">Liquid Metal Battery.</a> US patent. , (2015).</li><li>Lim, Z. B., 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=Synthesis+and+assessment+of+new+cyclopenta-2,4-dienone+derivatives+for+energy+storage+applications.">Synthesis and assessment of new cyclopenta-2,4-dienone derivatives for energy storage applications.</a> Synthetic Met. 200, 85-90 (2015).</li><li>Butterfield, A. M., Gilomen, B., Siegel, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kilogram-Scale+Production+of+Corannulene.">Kilogram-Scale Production of Corannulene.</a> Org. Process Res. Dev. 16, 664-676 (2012).</li><li>Elmorsy, S. S., Pelter, A., Smith, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+direct+production+of+tri-+and+hexa-substituted+benzenes+from+ketones+under+mild+conditions.">The direct production of tri- and hexa-substituted benzenes from ketones under mild conditions.</a> Tetrahedron Lett. 32, 4175-4176 (1991).</li><li>Zabula, A. V., Filatov, A. S., Spisak, S. N., Rogachev, A. Y., Petrukhina, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Main+Group+Metal+Sandwich:+Five+Lithium+Cations+Jammed+Between+Two+Corannulene+Tetraanion+Decks.">A Main Group Metal Sandwich: Five Lithium Cations Jammed Between Two Corannulene Tetraanion Decks.</a> Science. 333, 1008-1011 (2011).</li></ol>

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Ai Lises basati 1,3,5-triphenylbenzene, un campione con un colore chiaro dimostra che ha una bassa concentrazione di elettroni solvatate. Li x TPB (THF) 24,7 (per x = 1, 2, 3, 4) dimostra un comportamento nella sua conducibilità rispetto x simile a quello visto per Lises base di bifenile e naftalene 1, 2 .C&#39;è un aumento iniziale conducibilità con aumento di Li: rapporto PAH dal 1 al 2 ed una conseguente diminuzione della conducibilità all&#39;aumentare ulteriormente il r...

Le soluzioni elettrone solvatato litio (Lises) preparati con semplici idrocarburi policiclici aromatici a due anelli (IPA) come il bifenile e naftalene possono potenzialmente essere utilizzati come anodi liquidi in celle al litio refuelable 1-7. Nei Lises, questi semplici molecole PAH servito come i recettori di elettroni per elettroni solvatate da litio metallico disciolto. Progredendo da questi sistemi a due anelli, gli autori hanno da allora svolto studi di misurazione della conducibilità in Lises che sono preparati utilizzando IPA più complessi, che iniziano con il gruppo dei derivati ciclopenta-2,4-dienone 8. Questi includono IPA IPA di grandi dimensioni (&gt; due anelli di benzene) e IPA con sostituenti incorporati nella loro anelli aromatici. Una molecola PAH più grande con più di due anelli dovrebbe accogliere più atomi di litio per molecola PAH rispetto sia bifenile o naftalene conseguente Lises con maggiore densità di energia. L&#39;obiettivo di &#39;introduzioneing sostituenti in IPA è quello di rendere la PAH accetta elettroni più facilmente e diventare più stabile polianioni in Lises. Come parte del continuo impegno per sviluppare Lises con maggiore densità di energia, questo documento riferirà sulla caratterizzazione di Lises preparati con corannulene fatta dalla procedura letteratura 9 così come 1,3,5-triphenylbenzene, TPB sintetizzato da una letteratura leggermente modificata 10 . 1,3,5-triphenylbenzene, come mostrato nella Figura 1 (1), può essere classificato come un derivato bifenile con due anelli fenilici supplementari nelle posizioni 3 e 5 dello stesso anello. Poiché questa molecola ha quattro anelli benzenici, dovrebbe assorbimento 4 atomi di Li per molecola, che è più che per bifenile (massimo 2,5 equivalenti molari di Li per PAH in 0,5 M soluzione) e naftalene (&lt;2,5 equivalenti molari di litio per molecola) . Corannulene è un cinque-ring PAH disposti in una forma ciotola come mostrato nella Figura 1 (2). Zabula et al. 11 hanno dimostrato la fattibilità di dissoluzione litio metallico in una soluzione di corannulene / tetraidrofurano (THF) per formare una soluzione con cinque ioni Li + sandwich tra due tetraanions stabili di corannulene. <img alt="Figura 1" src="/files/ftp_upload/54366/54366fig1.jpg" /> Figura 1: Le strutture molecolari di 1,3,5-triphenylbenzene (1) e corannulene (2) 1,3,5-triphenylbenzene è classificato come un derivato bifenile con due anelli fenilici aggiuntivi in posizioni 3 e 5 dello stesso anello. . Corannulene è un PAH cinque anelli con i suoi cinque anelli di benzene disposti in una forma ciotola. <a href="https://www.jove.com/files/ftp_upload/54366/54366fig1large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a> Così, sia 1,3,5-triphenylbenzene e corannulene sono potenziali candidati per l&#39;alta energiaLises densità.

<table border="0" cellpadding="0" cellspacing="0" width="1005">
	<tbody>
		<tr height="31">
			<td height="31" style="height:31px;width:479px;">Biphenyl Reagentplus, 99.5%</td>
			<td style="width:136px;">Sigma Aldrich</td>
			<td style="width:187px;">B34656-1KG</td>
			<td style="width:204px;"></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;">Tetrahydrofuran Anhydrous, 99.9%, Inhibi</td>
			<td style="width:136px;">Sigma Aldrich</td>
			<td>401757-100ML</td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;">Iodine, Anhydrous, Beads, -10 Mesh, 99.999% trace metals basis&#160;</td>
			<td style="width:136px;">Sigma Aldrich</td>
			<td>451045-25G</td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;">Lithium iodide, anhydrous, 99.95% (metals basis)</td>
			<td style="width:136px;">Alfa Aesar</td>
			<td>40666</td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:479px;">Lithium Ion Conducting Glass ceramics (Diameter 1&#34; x 150 mm)&#160;</td>
			<td style="width:136px;">Ohara</td>
			<td style="width:187px;">LICGC(AG01)</td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:479px;">Lithium Foil&#160;</td>
			<td style="width:136px;">Alfa Aesar</td>
			<td style="width:187px;">010769.14</td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:479px;">Methanol anhydrous, 99.8%</td>
			<td style="width:136px;">Sigma Aldrich</td>
			<td>322415-100ML&#160;</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">CompactStat : Electrochemical Analyser with Impedance</td>
			<td style="width:136px;">Ivium Technologies</td>
			<td style="width:187px;">Not Applicable</td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:479px;">Cond 3310 Conductivity Meter</td>
			<td style="width:136px;">WTW</td>
			<td style="width:187px;">Not Applicable</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:479px;">Digital Multimeter, Model Fluke 179</td>
			<td style="width:136px;">Fluke Corporation</td>
			<td style="width:187px;">Not Applicable</td>
			<td></td>
		</tr>
		<tr height="120">
			<td height="120" style="height:120px;width:479px;">1,3,5-triphenylbenzene</td>
			<td style="width:136px;">Synthesized from acetpohenone according to procedure described in literature</td>
			<td style="width:187px;"></td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:479px;">Silicon tetrachloride</td>
			<td style="width:136px;">Sigma Aldrich</td>
			<td style="width:187px;">215120-100G</td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:479px;">acetophenone</td>
			<td style="width:136px;">TCI</td>
			<td style="width:187px;">A0061-500g</td>
			<td></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:479px;">Ethanol</td>
			<td style="width:136px;">Merck Millipore</td>
			<td style="width:187px;">1.00983.2511</td>
			<td></td>
		</tr>
	</tbody>
</table>

1,3,5-triphenylbenzene and corannulene as electron receptors for lithium solvated electron solutions

Gli autori riferiscono a studi di conducibilità effettuati su soluzioni di elettroni al litio solvatato (Lises) preparati utilizzando due tipi di idrocarburi policiclici aromatici (IPA), vale a dire 1,3,5-triphenylbenzene e corannulene, come recettori di elettroni. Gli IPA solidi sono stati sciolti in tetraidrofurano (THF) per formare una soluzione. Il litio metallico è stato quindi disciolto in queste soluzioni PAH / THF per fornire sia soluzioni blu blu o verde, colori che sono indicativi della presenza di elettroni solvatate. Le misure di conducibilità a temperatura ambiente a cui i Lises 1,3,5-triphenylbenzene basati, indicata con Li x TPB (THF) 24,7 (x = 1, 2, 3, 4), ha mostrato un aumento della conducibilità con aumento della Li: rapporto PAH da x = 1 a 2. Tuttavia, la conducibilità diminuito gradualmente all&#39;aumentare ulteriormente il rapporto. Infatti la conducibilità Li x TPB (THF) 24,7 per x = 4 è addirittura inferiore per x </em&gt; = 1. Tale comportamento è simile a quello dei Lises precedentemente riportati preparati da bifenile e naftalene. Conduttività in funzione della misura su Lises corannulene-based, indicati con Li x Cor (THF) 247 (x = 1, 2, 3, 4, 5), ha mostrato relazioni lineari con pendenze negative, ad indicare un comportamento metallico simile a bifenile e naftalen Lises based.

Reazione tra varie quantità di litio e miscele di 1,3,5-triphenylbenzene con THF fornisce soluzioni di colore blu blu o profondi verdastro come mostrato in Figura 2. Un colore chiaro indica che il particolare campione di Lises ha una bassa concentrazione di elettroni solvatate. 1,3,5-triphenylbenzene dimostra aumento della conducibilità con aumento della Li: rapporto PAH dal 1 al 2 in 0,5 M soluzione THF (Tabella 1). Tuttavia, il valore di conducibilità diminuisce gradualmente all&#3...

Watch this Scientific Journal Video about 1,3,5-Triphenylbenzene and Corannulene as Electron Receptors for Lithium Solvated Electron Solutions at JoVE.com

1,3,5-Triphenylbenzene and Corannulene as Electron Receptors for Lithium Solvated Electron Solutions

The authors report on conductivity studies carried out on lithium solvated electron solutions (LiSES) prepared using 1,3,5-triphenylbenzene (TPB) and corannulene as electron receptors.

1,3,5-Triphenylbenzene e corannulene come Electron recettori per litio solvatato Electron Solutions

The authors report on conductivity studies carried out on lithium solvated electron solutions (LiSES) prepared using two types of polyaromatic ...

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7.6K Views.  Nanyang Technological University. The authors report on conductivity studies carried out on lithium solvated electron solutions (LiSES) prepared using 1,3,5-triphenylbenzene (TPB) and corannulene as electron receptors.

Video: 1,3,5-Triphenylbenzene and Corannulene as Electron Receptors for Lithium Solvated Electron Solutions

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples.

Trace explosive vapors of TNT and RDX collected on sorbent-filled thermal desorption tubes were analyzed using a programmed temperature desorption system coupled to GC with an electron capture detector. The instrumental analysis is combined with direct liquid deposition method to reduce sample variability and account for instrumentation drift and losses.

Quantitativa Rilevamento di Trace vapori esplosivi di temperatura programmata Desorption Gas Detector cattura cromatografia-Electron

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive ...

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Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma sintering techniques. Polycrystalline ceramics possessing a unique morphology can be achieved by optimizing the process parameters, particularly spark plasma sintering heating rate. The phase and morphology of the synthesized ceramics were investigated in detail using X-ray diffraction, scanning electron microcopy and energy-dispersive X-ray spectroscopy. It was observed that the grains of these bulk Pr-doped SrTiO3 ceramics were enhanced with Pr-rich grain boundaries. Electronic and thermal transport properties were also investigated as a function of temperature and doping concentration. Such a microstructure was found to give rise to improved thermoelectric properties. Specifically, it resulted in a significant improvement in carrier mobility and the thermoelectric power factor. Simultaneously, it also led to a marked reduction in the thermal conductivity. As a result, a significant improvement (> 30%) in the thermoelectric figure of merit was achieved for the whole temperature range over all previously reported maximum values for SrTiO3-based ceramics. This synthesis demonstrates the steps for the preparation of bulk polycrystalline ceramics of non-uniformly Pr-doped SrTiO3.

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

A protocol for the synthesis and processing of polycrystalline SrTiO3 ceramics doped non-uniformly with Pr is presented along with the investigation of their thermoelectric properties.

Sintesi di non-uniforme Pr-drogato SrTiO<sub&gt; 3</sub&gt; Ceramica e le loro proprietà termoelettriche

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma ...

Characterizing Electron Transport through Living Biofilms

Here we demonstrate the method of electrochemical gating used to characterize electrical conductivity of electrode-grown microbial biofilms under physiologically relevant conditions.1 These measurements are performed on living biofilms in aqueous medium using source and drain electrodes patterned on a glass surface in a specialized configuration referred to as an interdigitated electrode (IDA) array. A biofilm is grown that extends across the gap connecting the source and drain. Potentials are applied to the electrodes (ES and ED) generating a source-drain current (ISD) through the biofilm between the electrodes. The dependency of electrical conductivity on gate potential (the average of the source and drain potentials, EG = [ED + ES]/2) is determined by systematically changing the gate potential and measuring the resulting source-drain current. The dependency of conductivity on gate potential provides mechanistic information about the extracellular electron transport process underlying the electrical conductivity of the specific biofilm under investigation. The electrochemical gating measurement method described here is based directly on that used by M. S. Wrighton2,3 and colleagues and R. W. Murray4,5,6 and colleagues in the 1980&#39;s to investigate thin film conductive polymers.

A protocol for measuring electrical conductivity of living microbial biofilms under physiologically relevant conditions is presented.

Caratterizzazione di trasporto dell'elettrone attraverso biofilm vivente

Here we demonstrate the method of electrochemical gating used to characterize electrical conductivity of electrode-grown microbial biofilms under ...

Synthesis and Characterization of Fe-doped Aluminosilicate Nanotubes with Enhanced Electron Conductive Properties

The goal of the protocol is to synthesize Fe-doped aluminosilicate nanotubes of the imogolite type with the formula (OH)3Al2-xFexO3SiOH. Doping with Fe aims at lowering the band gap of imogolite, an insulator with the chemical formula (OH)3Al2O3SiOH, and at modifying its adsorption properties towards azo-dyes, an important class of organic pollutants of both wastewater and groundwater.
Fe-doped nanotubes are obtained in two ways: by direct synthesis, where FeCl3 is added to an aqueous mixture of the Si and Al precursors, and by post-synthesis loading, where preformed nanotubes are put in contact with a FeCl3&#8226;6H2O aqueous solution. In both synthesis methods, isomorphic substitution of Al3+ by Fe3+ occurs, preserving the nanotube structure. Isomorphic substitution is indeed limited to a mass fraction of ~1.0% Fe, since at a higher Fe content (i.e., a mass fraction of 1.4% Fe), Fe2O3 clusters form, especially when the loading procedure is adopted. The physicochemical properties of the materials are studied by means of X-ray powder diffraction (XRD), N2 sorption isotherms at -196 &#176;C, high resolution transmission electron microscopy (HRTEM), diffuse reflectance (DR) UV-Vis spectroscopy, and &#950;-potential measurements. The most relevant result is the possibility to replace Al3+ ions (located on the outer surface of the nanotubes) by post-synthesis loading on preformed imogolite without perturbing the delicate hydrolysis equilibria occurring during nanotube formation. During the loading procedure, an anionic exchange occurs, where Al3+ ions on the outer surface of the nanotubes are replaced by Fe3+ ions. In Fe-doped aluminosilicate nanotubes, isomorphic substitution of Al3+ by Fe3+ is found to affect the band gap of doped imogolite. Nonetheless, Fe3+ sites on the outer surface of nanotubes are able to coordinate organic moieties, like the azo-dye Acid Orange 7, through a ligand-displacement mechanism occurring in an aqueous solution.

Here, we present a protocol to synthesize and characterize Fe-doped aluminosilicate nanotubes. The materials are obtained by either sol-gel synthesis upon addition of FeCl3&#8226;6H2O to the mixture containing the Si and Al precursors or by post-synthesis ionic exchange of preformed aluminosilicate nanotubes.

Sintesi e caratterizzazione di Fe-drogato Alluminosilicato nanotubi con una maggiore Electron proprietà conduttive

The goal of the protocol is to synthesize Fe-doped aluminosilicate nanotubes of the imogolite type with the formula (OH)3Al2-xFexO3SiOH. Doping with Fe ...

Liquid-cell Transmission Electron Microscopy for Tracking Self-assembly of Nanoparticles

Drying a nanoparticle dispersion is a versatile way to create self-assembled structures of nanoparticles, but the mechanism of this process is not fully understood. We have traced the trajectories of individual nanoparticles using liquid-cell transmission electron microscopy (TEM) to investigate the mechanism of the assembly process. Herein, we present the protocols used for liquid-cell TEM studies of the self-assembly mechanism. First, we introduce the detailed synthetic protocols used to produce uniformly sized platinum and lead selenide nanoparticles. Next, we present the microfabrication processes used to produce liquid cells with silicon nitride or silicon windows and then describe the loading and imaging procedures of the liquid-cell TEM technique. Several notes are included to provide helpful tips for the entire process, including how to manage the fragile cell windows. The individual motions of nanoparticles tracked by liquid-cell TEM revealed that changes in the solvent boundaries caused by evaporation affected the self-assembly process of nanoparticles. The solvent boundaries drove nanoparticles to primarily form amorphous aggregates, followed by flattening of the aggregates to produce a 2-dimensional (2D) self-assembled structure. These behaviors are also observed for different nanoparticle types and different liquid-cell compositions.

Here we introduce experimental protocols for the real-time observation of a self-assembly process using liquid-cell transmission electron microscopy.

Microscopia elettronica in trasmissione di liquidi-cellula per l'inseguimento auto-assemblaggio delle nanoparticelle

Drying a nanoparticle dispersion is a versatile way to create self-assembled structures of nanoparticles, but the mechanism of this process is not fully ...

Obtaining 3D Chemical Maps by Energy Filtered Transmission Electron Microscopy Tomography

Energy filtered transmission electron microscopy tomography (EFTEM tomography) can provide three-dimensional (3D) chemical maps of materials at a nanometric scale. EFTEM tomography can separate chemical elements that are very difficult to distinguish using other imaging techniques. The experimental protocol described here shows how to create 3D chemical maps to understand the chemical distribution and morphology of a material. Sample preparation steps for data segmentation are presented. This protocol permits the 3D distribution analysis of chemical elements in a nanometric sample. However, it should be noted that currently, the 3D chemical maps can only be generated for samples that are not beam sensitive, since the recording of filtered images requires long exposure times to an intense electron beam. The protocol was applied to quantify the chemical distribution of the components of two different heterogeneous catalyst supports. In the first study, the chemical distribution of aluminum and titanium in titania-alumina supports was analyzed. The samples were prepared using the swing-pH method. In the second, the chemical distribution of aluminum and silicon in silica-alumina supports that were prepared using the sol-powder and mechanical mixture methods was examined.

This paper describes a protocol to achieve 3D chemical maps combining energy filtered imaging and electron tomography. The chemical distribution of two catalyst supports formed by elements that are difficult to distinguish by other imaging techniques was studied. Each application consists of mapping overlapped chemical elements - respectively spaced-ionization edges.

Come ottenere mappe 3D chimiche di energia filtrata tomografia di microscopia elettronica di trasmissione

Energy filtered transmission electron microscopy tomography (EFTEM tomography) can provide three-dimensional (3D) chemical maps of materials at a ...

An Experimental Protocol for Femtosecond NIR/UV - XUV Pump-Probe Experiments with Free-Electron Lasers

This protocol describes key steps in performing and analyzing femtosecond pump-probe experiments that combine a femtosecond optical laser with a free-electron laser. This includes methods to establish the spatial and temporal overlap between the optical and free-electron laser pulses during the experiment, as well as important aspects of the data analysis, such as corrections for arrival time jitter, which are necessary to obtain high-quality pump-probe data sets with the best possible temporal resolution. These methods are demonstrated for an exemplary experiment performed at the FLASH (Free-electron LASer Hamburg) free-electron laser in order to study ultrafast photochemistry in gas-phase molecules by means of velocity map ion imaging. However, most of the strategies are also applicable to similar pump-probe experiments using other targets or other experimental techniques.

This protocol describes the key steps for performing and analyzing pump-probe experiments combining a femtosecond optical laser with a free-electron laser in order to study ultrafast photochemical reactions in gas-phase molecules.

Un protocollo sperimentale per Femtosecond NIR/UV - esperimenti di Pump-Probe XUV con laser a elettroni liberi

This protocol describes key steps in performing and analyzing femtosecond pump-probe experiments that combine a femtosecond optical laser with a ...

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The devices are patterned from epoxy glue using soft lithography and are suitable for in situ X-ray diffraction experiments at room temperature. The sample wells are lidded on both sides with polymeric polyimide foil windows that allow diffraction data collection with low X-ray background. This fabrication method is undemanding and inexpensive. After the sourcing of a SU-8 master wafer, all fabrication can be completed outside of a cleanroom in a typical research lab environment. The chip design and fabrication protocol utilize capillary valving to microfluidically split an aqueous reaction into defined nanoliter sized droplets. This loading mechanism avoids the sample loss from channel dead-volume and can easily be performed manually without using pumps or other equipment for fluid actuation. We describe how isolated nanoliter sized drops of protein solution can be monitored in situ by dynamic light scattering to control protein crystal nucleation and growth. After suitable crystals are grown, complete X-ray diffraction datasets can be collected using goniometer based in situ fixed target serial X-ray crystallography at room temperature. The protocol provides custom scripts to process diffraction datasets using a suite of software tools to solve and refine the protein crystal structure. This approach avoids the artefacts possibly induced during cryo-preservation or manual crystal handling in conventional crystallography experiments. We present and compare three protein structures that were solved using small crystals with dimensions of approximately 10-20 &#181;m grown in chip. By crystallizing and diffracting in situ, handling and hence mechanical disturbances of fragile crystals is minimized. The protocol details how to fabricate a custom X-ray transparent microfluidic chip suitable for in situ serial crystallography. As almost every crystal can be used for diffraction data collection, these microfluidic chips are a very efficient crystal delivery method.

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes in detail how to fabricate and operate microfluidic devices for X-ray diffraction data collection at room temperature. Additionally, it describes how to monitor protein crystallization by dynamic light scattering and how to process and analyze obtained diffraction data.

Chip microfluidici per dispersione della luce dinamica In Situ diffrazione di raggi x di cristallo ed In Situ per la cristallografia seriale

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The ...

A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various precursor noble metal ions with reducing agents in a 1:1 (v/v) ratio results in the formation of metal gels within seconds to minutes compared to much longer synthesis times for other techniques such as sol-gel. Conducting the reduction step in a microcentrifuge tube or small volume conical tube facilitates a proposed nucleation, growth, densification, fusion, equilibration model for gel formation, with final gel geometry smaller than the initial reaction volume. This method takes advantage of the vigorous hydrogen gas evolution as a by-product of the reduction step, and as a consequence of reagent concentrations. The solvent accessible specific surface area is determined with both electrochemical impedance spectroscopy and cyclic voltammetry. After rinsing and freeze drying, the resulting aerogel structure is examined with scanning electron microscopy, X-ray diffractometry, and nitrogen gas adsorption. The synthesis method and characterization techniques result in a close correspondence of aerogel ligament sizes. This synthesis method for noble metal aerogels demonstrates that high specific surface area monoliths may be achieved with a rapid and direct reduction approach.

A rapid, direct solution-based reduction synthesis method to obtain Au, Pd, and Pt aerogels is presented.

Un metodo di sintesi rapida per Au, Pd e Pt Aerogels tramite riduzione diretta basata su soluzione

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various ...

Pretargeted Radioimmunotherapy Based on the Inverse Electron Demand Diels-Alder Reaction

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can result in high radiation doses to healthy tissues. Perhaps not surprisingly, several different strategies have been developed to circumvent this troubling limitation. One of the most promising of these approaches is pretargeted radioimmunotherapy (PRIT). PRIT is predicated on decoupling the radionuclide from the immunoglobulin, injecting them separately, and then allowing them to combine in vivo at the target tissue. This approach harnesses the exceptional tumor-targeting properties of antibodies while skirting their pharmacokinetic drawbacks, thereby lowering radiation doses to non-target tissues and facilitating the use of radionuclides with half-lives that are considered too short for use in traditional radioimmunoconjugates. Over the last five years, our laboratory and others have developed an approach to in vivo pretargeting based on the inverse electron-demand Diels-Alder (IEDDA) reaction between trans-cyclooctene (TCO) and tetrazine (Tz). This strategy has been successfully applied to pretargeted positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging with a variety of antibody-antigen systems. In a pair of recent publications, we have demonstrated the efficacy of IEDDA-based PRIT in murine models of pancreatic ductal adenocarcinoma and colorectal carcinoma. In this protocol, we describe protocols for PRIT using a 177Lu-DOTA-labeled tetrazine radioligand ([177Lu]Lu-DOTA-PEG7-Tz) and a TCO-modified variant of the colorectal cancer targeting huA33 antibody (huA33-TCO). More specifically, we will describe the construction of huA33-TCO, the synthesis and radiolabeling of [177Lu]Lu-DOTA-PEG7-Tz, and the performance of in vivo biodistribution and longitudinal therapy studies in murine models of colorectal carcinoma.

This protocol describes the synthesis and characterization of a trans-cyclooctene (TCO)-modified antibody and a 177Lu-labeled tetrazine (Tz) radioligand for pretargeted radioimmunotherapy (PRIT). In addition, it details the use of these two constructs for in vivo biodistribution and longitudinal therapy studies in a murine model of colorectal cancer.

Pretargeted Radioimmunotherapy basato sulla reazione di Diels-Alder domanda inversa Electron

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can ...