The authors would like to acknowledge the support from the Department of Earth Sciences, Uppsala University for supporting part of this research.

1. Funzionalizzazione di multiwalled nanotubi di carbonio <ol><li> Eseguire l&#39;intera fase di funzionalizzazione all&#39;interno di una cappa aspirante, con occhiali di sicurezza, guanti e camice da laboratorio. Misurare 24 ml di acido solforico e 8 ml di acido nitrato utilizzando un cilindro graduato e poi trasferirli in un becher. Aggiungere 32 mg di MWCNT non trattati in un becher con stagno contenitore della lamina in una bilancia analitica (concentrazione finale dovrebbe essere di 1 mg / ml di miscela di acidi). </li><li> In primo luogo, tenere il bicchiere con MWCNT e la miscela di acido nel pulitore ad ultrasuoni (bagno) per 2 ore a temperatura ambiente. Poi, il calore e mescolare la soluzione MWCNT acido per 5 ore a 90 ° C con un piatto caldo. </li><li> Filtrare la sospensione CNT con un diametro PTFE membrana filtrante 0,2 micron pori posto su un supporto del filtro, e utilizzare il vuoto per aiutare la filtrazione. Eseguire la porzione filtrazione porzione e utilizzare diverse membrane filtranti (circa 1/4 th della miscela sopra per porzione per un filtro). Aggiungere acqua bollentedurante il processo di filtrazione per filtrare la soluzione acida finché il pH della miscela diventa maggiore di 5. </li><li> Sempre rompere il vuoto prima che sia spento e non introdurre nulla nel sistema del vuoto. Utilizzare un bicchiere conico per raccogliere il liquido di scarto. </li><li> Versare acido filtrato in un contenitore per rifiuti (invia il contenitore rifiuti ad un impianto di trattamento dei rifiuti o diluire il liquido prima scarico nel lavandino aggiungendo almeno dieci volte di acqua di rubinetto). </li><li> Trasferire le membrane filtranti con MWCNT trattenuti in evaporazione piatti e mettere i piatti in essiccatore (contiene circa 100 g di gel di silice) e creare un ambiente sotto vuoto (lasciare il vuoto per circa 1 ora) per CNT per completare l&#39;asciugatura (circa 24 ore ). <ol><li> Raschiare le CNT dalle membrane accuratamente con spatola e trasferire le particelle in un contenitore pulito. Pesare la polvere MWCNT ed etichettare il contenitore per uso futuro. </li></ol></li></ol> 2. Porosiamo Media per gli esperimenti di trasporto <ol><li> Preparare 0,1 M HCl soluzione per il lavaggio acido di sabbia silicea. <ol><li> Eseguire tutti questi passaggi all&#39;interno di una cappa aspirante con occhiali di sicurezza, guanti e camice da laboratorio. Aggiungere 1 L di acqua deionizzata in un pallone da 2 L. Misurare 8 ml di 37% HCl utilizzando un cilindro graduato. </li><li> Aggiungere l&#39;HCl in acqua deionizzata con attenzione. Agitare accuratamente il pallone per aiutare la miscelazione. </li></ol></li><li> Lavare la sabbia con la soluzione HCl preparata. <ol><li> Pesare circa 1.000 g sabbia. Aggiungere 1/3 di sabbia nel pallone con la soluzione di HCl e agitare il matraccio due volte per aiutare miscelazione quindi aggiungere resto della sabbia (1/3 della sabbia ogni volta). </li><li> Agitare la beuta per tre volte e lasciare l&#39;acido con sabbia per 30 min. </li><li> Versare il liquido del matraccio a contenitore di rifiuti acidi e risciacquare sabbia con acqua deionizzata almeno 8 volte. </li></ol></li><li> Lavare la sabbia con una soluzione di H 2 O 2. <ol><li> Aggiungere 700 ml di acqua deionizzata inil pallone con sabbia poi misurare 40 ml di 30% H 2 O 2 soluzione con un cilindro graduato. </li><li> Aggiungere la soluzione di H 2 O 2 in beuta con sabbia e agitare due volte per aiutare miscelazione. Quindi aggiungere altri 40 ml di 30% H 2 O 2 soluzione 3 volte finché c&#39;è 160 ml H 2 O 2 totale nel pallone. </li><li> Agitare e miscelare la soluzione e sabbia ogni volta e lasciare la soluzione di H 2 O 2 con sabbia per 40 minuti per consentire la reazione sia completata. Agitare il pallone e mescolare la sabbia con una bacchetta di plastica ogni 10 min. </li><li> Decantare il liquido verso il lavandino e correre l&#39;acqua del rubinetto per 30 sec. </li></ol></li><li> Risciacquare e asciugare la sabbia. <ol><li> Sciacquare sabbia con acqua deionizzata almeno 8 volte per sbarazzarsi di qualsiasi soluzione o lasciati prodotti di reazione. Agitare e mescolare accuratamente durante il risciacquo. </li><li> Mettere matraccio con sabbia sciacquati in un forno (105 ° C) per 24 ore ad asciugare, poi sabbia fuori del forno medianteforno a guanto e lasciare al banco per 2 ore per la sabbia si raffreddi. </li><li> Trasferire la sabbia pulita in un contenitore di plastica. Segnare il contenitore e posizionarlo in un ripiano appropriata per essere pronti per l&#39;uso. </li></ol></li></ol> 3. Esperimenti Colonna <ol><li> Preparazione della soluzione di sfondo. <ol><li> Preparare appropriato chimica soluzione di sfondo per l&#39;esperimento di colonna. </li><li> Utilizzare 0,1 M HCl e 0,1 soluzioni M NaOH per regolare il pH e sale NaCl ottenere un&#39;adeguata forza ionica per il seguente esperimento. </li></ol></li><li> Selezione della colonna. <ol><li> Scegliere una colonna di vetro di 2,5 cm di diametro e lunghezza 15 cm per questo esperimento (pH: 5 e forza ionica: 2 mM nello studio corrente). Utilizzare un filtro a rete di acciaio (0,2 mm) su entrambi i lati della colonna di vetro. </li><li> Lavare i tubi collegati alla colonna e riempire con la soluzione di fondo (o la soluzione MWCNT finché la valvola a 3 vie per controllare il tipo di flusso di liquido (MWCNT solution o soluzione sfondo) come mostrato in Figura 1. </li></ol></li><li> Wet-imballaggio della colonna. <ol><li> Pesare il sabbia pulita su scala e prendere 124 g di sabbia pulita per la dimensione di colonna selezionata. </li><li> Utilizzare una pompa peristaltica di alta precisione. Calibrare la pompa per ottenere 2 ml / min di flusso di liquido. </li><li> Avviare la pompa per riempire la colonna dal basso finché il livello dell&#39;acqua è un paio di centimetri dal fondo della colonna. Mettere circa 1/10 della sabbia misurata alla volta nella colonna ma assicurarsi che il livello di sabbia non arriva al di sopra del livello dell&#39;acqua nella colonna. Continua il flusso d&#39;acqua alla colonna continuamente alloggiare sopra del livello di sabbia. </li><li> Chiudere il tappo colonna con adeguata rete filtrante dopo completo riempimento. </li><li> Lasciare la colonna impaccata di fluire per almeno 1 ora. I singoli parametri della colonna sono indicati nella Tabella 1. </li></ol></li><li> Test Tracer. <ol><li> LA Scrostata dell&#39;esperimento colonna con un test tracciante prima degli esperimenti soluzione MWCNT. </li><li> Accendere la valvola a 3 vie per la soluzione tracciante (con cibo colore tracciante a 20 mg / L) per avviare l&#39;esperimento. </li><li> Raccogliere i campioni deflusso dalla colonna ad ogni 2 min (cioè, 4 ml / campioni in ciascun tubo di campionamento) utilizzando il raccoglitore di frazioni collegato come mostrato nella Figura 1. </li><li> Continua per iniettare la soluzione tracciante per un volume dei pori 4.32 (cioè, la soluzione passa 4,32 volte dello spazio vuoto totale dei pori nella colonna impaccata di sabbia), che è anche chiamata fase I dell&#39;esperimento. </li><li> Accendere la valvola a 3 vie per scorrere la soluzione di fondo (DI acqua in caso di esperimento tracciante) per un altro volume 4.32 pori. </li></ol></li><li> Preparazione della soluzione MWCNT. <ol><li> Fare un, funzionalizzato soluzione MWCNT dispersa mettendo 15 mg di MWCNT funzionalizzate in un bicchiere da 300 ml contenente 200 ml di soluzione acquosa (con solutio desideratan chimica cioè, pH 5 e 2 mM forza ionica nella condizione sperimentale attuale) e utilizzando una sonda omogeneizzatore ad ultrasuoni collocato nel becher (con potenza di 40% per 15 min). Mescolare la soluzione MWCNT dispersa con altri 800 ml della stessa soluzione acquosa per raggiungere la concentrazione MWCNT di 15 mg / L. </li><li> Eseguire microscopia elettronica a scansione (SEM) analisi dell&#39;immagine di soluzione per la loro forma e dimensione della nanoparticella dopo funzionalizzazione. </li></ol></li><li> Esperimento trasporti MWCNT. <ol><li> Accendere la valvola a 3 vie per la soluzione MWCNT per avviare l&#39;esperimento di colonna. </li><li> Raccogliere i campioni deflusso dalla colonna in ogni 2 minuti con il raccoglitore di frazioni collegato. </li><li> Iniettare la soluzione MWCNT per un volume di 4.32 pori (fase I dell&#39;esperimento). </li><li> Accendere la valvola a 3 vie per scorrere la soluzione di fondo per un altro volume 4.32 pori, che si chiama la fase II della sperimentazione. </li><li> Cambiare il tubo di iniezione di background soluzione in bottiglia di acqua DI (dopo l&#39;arresto della pompa per un momento per evitare l&#39;ingresso di aria dal tubo) e continuare il flusso per un altro volume dei pori 4,32, che è chiamata fase III dell&#39;esperimento. </li></ol></li><li> L&#39;analisi dei campioni. <ol><li> Trasferire tutti i campioni tubo da raccoglitore di frazioni in un rack tubo. </li><li> Preparare uno spettrofotometro UV / VIS per l&#39;analisi del campione, vale a dire, scoprire la lunghezza d&#39;onda di scansione appropriato per la quantificazione dei campioni raccolti. Utilizzare 400 nm di una soluzione MWCNT e una lunghezza d&#39;onda 333 nm per soluzione tracciante. </li><li> Scansione di tutti i campioni prelevati dalla colonna durante le fasi I, II, e III utilizzando una cuvetta a 400 nm di lunghezza d&#39;onda (o una lunghezza d&#39;onda diversa se ritenuto più appropriato nel passaggio precedente) e memorizzare i dati. </li><li> Raccogliere i dati dal spettrofotometro e tracciare vs tempo o volume dei pori per ottenere curve innovative come mostrato nei risultati rappresentativi (ad esempio, figura3). </li><li> Effettuare dimensioni di analisi (di diametro idrodinamica) di afflusso e deflusso campioni utilizzando zeta sizer e condurre la visualizzazione studiato per entrambi i campioni di afflusso e deflusso utilizzando la microscopia elettronica a scansione. </li></ol></li></ol>

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The authors declare that they have no competing financial interests.

Effetto della funzionalizzazione MWCNT Come mostra la Figura 2 conferma la stabilità del MWCNT funzionalizzati, la differenza osservata volume eluito di MWCNT era dovuto funzionalizzazione e in particolare per l&#39;aggiunta di carbossile (-COOH) gruppi alla superficie dei MWCNT (Figure 3 e 4). Nel processo di funzionalizzazione simile, la presenza di ossigeno è stata confermata mediante spettroscopia fotoelettronica a rag...

Con il recente sviluppo nel campo delle nanotecnologie che utilizza vari tipi di nanoparticelle per migliorare una serie di tecnologie in settori quali la tecnologia dell&#39;informazione, l&#39;energia, scienze ambientali, medicina, la sicurezza del territorio, la sicurezza alimentare, e il trasporto; una conoscenza approfondita del trasporto e la conservazione di nanoparticelle nel suolo e nelle acque sotterranee è fondamentale per la valutazione del rischio, nonché applicazioni ambientali di nanoparticelle ingegnerizzate 1-3. I nanotubi di carbonio (CNT) sono una delle nanoparticelle a base di carbonio più prodotte 2,4. CNT sono la forma lunga e cilindrica di grafene con diametro tipicamente inferiore a 100 nm e una lunghezza nell&#39;intervallo di 100 nm a 50 micron. Essi hanno proprietà uniche, che hanno accelerato il loro impiego in molte applicazioni, come l&#39;elettronica, ottica, cosmetici e tecnologie biomediche (ad esempio, materiali compositi) 5. Con maggiore uso, vi è anche un aumento risk di esposizione umana e l&#39;effetto sulla salute e conseguenze negative ecologiche seguenti CNT e altri nanomateriali di carbonio basato disposizione per l&#39;ambiente 5-8. Senza modificazioni superficiali (unfunctionalized), CNT sono estremamente idrofoba e tendono ad aggregarsi in una soluzione acquosa. CNT funzionalizzati possono, tuttavia, rimangono disperse e stabile in soluzioni acquose e sono utilizzati a fini biomedici, come la consegna della droga 9. Qui è essenziale che i CNT rimangono dispersi e mobilitate, quindi il farmaco possono essere forniti all&#39;interno del corpo umano 10. D&#39;altra parte, per ridurre i rischi ambientali, vi è la necessità per studi focalizzati su come per immobilizzare i CNT per evitare il loro ingresso in falde acquifere e risorse di acqua potabile 11. Recenti studi hanno riportato l&#39;effetto tossico del CNT sugli organismi viventi e dei rischi anche per gli ecosistemi in termini di CNT che entrano e si accumulano nelle catene alimentari, dal momento cheCNT sono difficili da biodegradare 5,8. Anche con sistemi di sbarramento in discariche contenenti CNT, può essere possibile per CNT di passare attraverso le barriere. In questi casi, i CNT potrebbero entrare in bacini idrici sotterranei ei corpi idrici superficiali. Come regolamenti di smaltimento CNT non sono ben definiti e meccanismi di trasporto sono poco conosciuti, una migliore comprensione della mobilità del CNT è necessario formulare e progettare sistemi appropriati di smaltimento 12. Pertanto, è importante studiare e comprendere il destino e trasporto di CNT in mezzi porosi e l&#39;effetto di fattori fisici e chimici comunemente presenti nell&#39;ambiente sottosuolo sulla superficie modificata ritenzione CNT. Un certo numero di ricerca è stata effettuata sugli effetti della granulometria collettore 13-15, portata 16, e proprietà superficiali dei grani 17 sul trasporto di nanoparticelle nei mezzi porosi. Tuttavia, le indagini sistematiche sugli effetti di soluzioni peion chimica (quali pH e forza ionica) sulla possibile deposizione sulle superfici collettori sono ancora limitate 18-20. Inoltre, l&#39;effetto combinato di fattori fisici, soluzione chimica del mezzo, e proprietà di superficie dei nanotubi di carbonio non è ben compreso e variano in letteratura diversi. In questo studio, un metodo di preparazione per la modifica della superficie di MWCNT sarà dimostrato con una colonna sistematica su scala di laboratorio imballato con acido puliti sabbia di quarzo viene utilizzato per studiare il trasporto, conservazione e rimobilizzazione di CNT-modificato superficiali in mezzi porosi saturi .

<table border="0" cellpadding="0" cellspacing="0" width="750">
	<tbody>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">Name of Material/ Equipments</td>
			<td style="width:228px;">Company</td>
			<td style="width:169px;">Catalog Number</td>
			<td style="width:171px;">Comments/Description</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">MWCNT</td>
			<td style="width:228px;">Cheap Tubes Inc., USA</td>
			<td style="width:169px;">sku-03040304</td>
			<td style="width:171px;">Purchased as semi-functionlized powder</td>
		</tr>
		<tr height="148">
			<td height="148" style="height:148px;width:183px;">Quartz sand</td>
			<td style="width:228px;">Sibelco Nordic, Baskarp, Sweden</td>
			<td style="width:169px;">B44</td>
			<td style="width:171px;">Purchased with more than 91% silica sand</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">H2SO4</td>
			<td style="width:228px;">VWR</td>
			<td style="width:169px;">1.01833.2500</td>
			<td style="width:171px;">95-97% purity</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">HNO3</td>
			<td style="width:228px;">VWR</td>
			<td style="width:169px;">1.00441.1000</td>
			<td style="width:171px;">70% purity</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">HCl</td>
			<td style="width:228px;">VWR</td>
			<td style="width:169px;">1.00317.2500</td>
			<td style="width:171px;">37-38% purity</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">H2O2</td>
			<td style="width:228px;">VWR</td>
			<td style="width:169px;">23615.248</td>
			<td style="width:171px;">30% purity</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">NaCl</td>
			<td style="width:228px;">VWR</td>
			<td style="width:169px;">1.06404.0500</td>
			<td style="width:171px;">99.5% purity</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:183px;">NaOH</td>
			<td style="width:228px;">Sigma-Aldrich</td>
			<td style="width:169px;">S8045-500G</td>
			<td style="width:171px;">99.99% pur pellets&#160;</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">Ultrasonic Homogenizer</td>
			<td style="width:228px;">Biologics Inc. Manassas, Virginia</td>
			<td style="width:169px;">Model 3000, 0-127-0002</td>
			<td style="width:171px;">Operated for fix time interval</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:183px;">Sonicator (bath)</td>
			<td style="width:228px;">Kerry Ultrasonic Ltd</td>
			<td style="width:169px;">1808</td>
			<td style="width:171px;">Common bath sonicator</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">Peristaltic pump</td>
			<td style="width:228px;">Ismantec, Glattbrugg, Switzerland</td>
			<td style="width:169px;">ISM931</td>
			<td style="width:171px;">Work with tygon tubing in the pump</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:183px;">Spectrophotometer</td>
			<td style="width:228px;">Hach Lange</td>
			<td style="width:169px;">DR500, LPV408.99.0001</td>
			<td style="width:171px;">Operate with manual cuvette as well as automated sampling</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:183px;">pH meter</td>
			<td style="width:228px;">Metrohm</td>
			<td style="width:169px;">781</td>
			<td style="width:171px;">pH analysis</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">Glass column</td>
			<td style="width:228px;">Chromaflex</td>
			<td style="width:169px;">420830-1510</td>
			<td style="width:171px;">Column with adjustable cap</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:183px;">Fraction collector</td>
			<td style="width:228px;">Spectrum Labs Europe</td>
			<td style="width:169px;">CF-2, 124846</td>
			<td style="width:171px;">Fixed at regular interval of time</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:183px;">Fraction collector tubes</td>
			<td style="width:228px;">VWR</td>
			<td style="width:169px;">212-9599</td>
			<td style="width:171px;">6 ml volume glass tube</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:183px;">Hot plate stir</td>
			<td style="width:228px;">Thermo Scientific</td>
			<td style="width:169px;">SP131320-33</td>
			<td style="width:171px;">Adjustable tempurature</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:183px;">Oven</td>
			<td style="width:228px;">Elektro Helios</td>
			<td style="width:169px;">259</td>
			<td style="width:171px;">For oven dry of sand</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:183px;">Balance</td>
			<td style="width:228px;">Mettler Toledo</td>
			<td style="width:169px;">AE 160</td>
			<td style="width:171px;">For accurate weight</td>
		</tr>
	</tbody>
</table>

transport of surface-modified carbon nanotubes through a soil column

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, electronics and biomedical applications. Due to their accelerating production and use, CNTs constitute a potential environmental risk if they are released to soil and groundwater systems. It is therefore essential to improve the current understanding of environmental fate and transport of CNTs. The transport and retention of CNTs in both natural and artificial media have been reported in literature, but the findings widely vary and are thus not conclusive. There are a number of physical and chemical parameters responsible for variation in retention and transport. In this study, a complete procedure of selected multiwalled carbon nanotubes (MWCNTs) is presented starting from their surface modification to a complete set of laboratory column experiments at critical physical and chemical scenarios. Results indicate that the stability of the commercially available MWCNTs are critical with their attached surface functional group which can also influence the transport and retention of MWCNT through the surrounding medium.

Effetto della funzionalizzazione MWCNT La soluzione MWCNT funzionalizzato e dispersa è stato sigillato nel becher per consentire alla soluzione di raggiungere l&#39;equilibrio. Non c&#39;era né sedimentazione né aggregazione osservato nella soluzione di riserva dopo sonicazione, come il diametro idrodinamico MWCNT (1.619 ± 262 nm) nella soluzione è rimasta la stessa per sei mesi di sonicazione (Figura 2). Per studiare l&#39;effetto della funzionalizzazi...

Watch this Scientific Journal Video about Transport of Surface-modified Carbon Nanotubes through a Soil Column at JoVE.com

Transport of Surface-modified Carbon Nanotubes through a Soil Column

Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles.

Trasporto di nanotubi di carbonio modificati superficie attraverso una colonna di terreno

Carbon nanotubes (CNTs) are widely manufactured nanoparticles, which are being utilized in a number of consumer products, such as sporting goods, ...

transport-of-surface-modified-carbon-nanotubes-through-a-soil-column

Research

JoVE Journal

Chemistry

9.4K Views.  Nalanda University. Surface properties of a nanoparticle are important for their interaction with the surrounding medium. Therefore the surface modification of carbon nanotubes can be critical for their transport and retention through porous media. Here, lab scale column experiments are used to understand the possible transport and retention of these nanoparticles. 

Video: Transport of Surface-modified Carbon Nanotubes through a Soil Column

Dependence of Laser-induced Breakdown Spectroscopy Results on Pulse Energies and Timing Parameters Using Soil Simulants

The dependence of some LIBS detection capabilities on lower pulse energies (&lt;100 mJ) and timing parameters were examined using synthetic silicate samples. These samples were used as simulants for soil and contained minor and trace elements commonly found in soil at a wide range of concentrations. For this study, over 100 calibration curves were prepared using different pulse energies and timing parameters; detection limits and sensitivities were determined from the calibration curves. Plasma temperatures were also measured using Boltzmann plots for the various energies and the timing parameters tested. The electron density of the plasma was calculated using the full-width half maximum (FWHM) of the hydrogen line at 656.5 nm over the energies tested. Overall, the results indicate that the use of lower pulse energies and non-gated detection do not seriously compromise the analytical results. These results are very relevant to the design of field- and person-portable LIBS instruments.

LIBS detection capabilities on soil simulants were tested using a range of pulse energies and timing parameters. Calibration curves were used to determine detection limits and sensitivities for different parameters. Generally, the results showed that there was not a significant reduction in detection capabilities using lower pulse energies and non-gated detection.

Dipendenza della Laser-Induced Breakdown Spectroscopy Risultati su energie di impulso e parametri di temporizzazione utilizzo di suolo Simulanti

The  dependence of some LIBS detection capabilities on lower pulse energies (&lt;100  mJ) and timing parameters were examined using synthetic silicate ...

Ricerca

Chimica

An Inverse Analysis Approach to the Characterization of Chemical Transport in Paints

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in understanding contaminant mass transport and the ability to decontaminate materials. If a material is contaminated, over time, the transport of highly toxic chemicals (such as chemical warfare agent species) out of the material can result in vapor exposure or transfer to the skin, which can result in percutaneous exposure to personnel who interact with the material. Due to the high toxicity of chemical warfare agents, the release of trace chemical quantities is of significant concern. Mapping subsurface concentration distribution and transport characteristics of absorbed agents enables exposure hazards to be assessed in untested conditions. Furthermore, these tools can be used to characterize subsurface reaction dynamics to ultimately design improved decontaminants or decontamination procedures. To achieve this goal, an inverse analysis mass transport modeling approach was developed that utilizes time-resolved mass spectroscopy measurements of vapor emission from contaminated paint coatings as the input parameter for calculation of subsurface concentration profiles. Details are provided on sample preparation, including contaminant and material handling, the application of mass spectrometry for the measurement of emitted contaminant vapor, and the implementation of inverse analysis using a physics-based diffusion model to determine transport properties of live chemical warfare agents including distilled mustard (HD) and the nerve agent VX.

In this paper, a procedure for quantifying the mass transport parameters of chemicals in various materials is presented. This process involves employing an inverse-analysis based diffusion model to vapor emission profiles recorded by real-time, mass spectrometry in high vacuum.

Un approccio di analisi inversa per la caratterizzazione dei Trasporti Chemical nelle vernici

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in ...

Tuning a Parallel Segmented Flow Column and Enabling Multiplexed Detection

Active flow technology (AFT) is new form of column technology that was designed to overcome flow heterogeneity to increase separation performance in terms of efficiency and sensitivity and to enable multiplexed detection. This form of AFT uses a parallel segmented flow (PSF) column. A PSF column outlet end-fitting consists of 2 or 4 ports, which can be multiplexed to connect up to 4 detectors. The PSF column not only allows a platform for multiplexed detection but also the combination of both destructive and non-destructive detectors, without additional dead volume tubing, simultaneously. The amount of flow through each port can also be adjusted through pressure management to suit the requirements of a specific detector(s). To achieve multiplexed detection using a PSF column there are a number of parameters which can be controlled to ensure optimal separation performance and quality of results; that is tube dimensions for each port, choice of port for each type of detector and flow adjustment. This protocol is intended to show how to use and tune a PSF column functioning in a multiplexed mode of detection.

Here, we present a protocol for the operation and tuning of parallel segmented flow chromatography columns to enable multiplexed detection.

Ottimizzazione di una colonna parallela segmentata Flow e Abilitazione rilevamento Multiplexer

Active flow technology (AFT) is new form of column technology that was designed to overcome flow heterogeneity to increase separation performance in terms ...

Curtain Flow Column: Optimization of Efficiency and Sensitivity

Active Flow Technology (AFT) is a form of column technology that increases the separation performance of a HPLC column through the use of a specially purpose built multiport end-fitting(s). Curtain Flow (CF) columns belong to the AFT suite of columns, specifically the CF column is designed so that the sample is injected into the radial central region of the bed and a curtain flow of mobile phase surrounding the injection of solute prevents the radial dispersion of the sample to the wall. The column functions as an 'infinite diameter' column. The purpose of the design is to overcome the radial heterogeneity of the column bed, and at the same time maximize the sample load into the radial central region of the column bed, which serves to increase detection sensitivity. The protocol described herein outlines the system and CF column set up and the tuning process for an optimized infinite diameter 'virtual' column.

Here, we present a protocol for the operation and optimization of Active Flow Technology (AFT) column in Curtain flow (CF) mode for enhanced separation performance.

Tenda Colonna flusso: ottimizzazione dell&#39;efficienza e della sensibilità

Active Flow Technology (AFT) is a form of column technology that increases the separation performance of a HPLC column through the use of a specially ...

Facile Preparation of Internally Self-assembled Lipid Particles Stabilized by Carbon Nanotubes

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled (functionalized) CNTs are used as stabilizers to produce Pickering type oil-in-water (O/W) emulsions. Lipids namely, Dimodan U and Phytantriol are used as emulsifiers, which in excess water self-assemble into the bicontinuous cubic Pn3m phase. This highly viscous phase is fragmented into smaller particles using a probe ultrasonicator in presence of conventional surfactant stabilizers or CNTs as done here. Initially, the CNTs (powder form) are dispersed in water followed by further ultrasonication with the molten lipid to form the final emulsion. During this process the CNTs get coated with lipid molecules, which in turn are presumed to surround the lipid droplets to form a particulate emulsion that is stable for months. The average size of CNT-stabilized nanostructured lipid particles is in the submicron range, which compares well with the particles stabilized using conventional surfactants. Small angle X-ray scattering data confirms the retention of the original Pn3m cubic phase in the CNT-stabilized lipid dispersions as compared to the pure lipid phase (bulk state). Blue shift and lowering of the intensities in characteristic G and G&#39; bands of CNTs observed in Raman spectroscopy characterize the interaction between CNT surface and lipid molecules. These results suggest that the interactions between the CNTs and lipids are responsible for their mutual stabilization in aqueous solutions. As the concentrations of CNTs employed for stabilization are very low and lipid molecules are able to functionalize the CNTs, the toxicity of CNTs is expected to be insignificant while their biocompatibility is greatly enhanced. Hence the present approach finds a great potential in various biomedical applications, for instance, for developing hybrid nanocarrier systems for the delivery of multiple functional molecules as in combination therapy or polytherapy.

We report on a smart application of carbon nanotubes for kinetic stabilization of lipid particles that contain self-assembled nanostructures in their cores. The preparation of lipid particles requires rather low concentrations of carbon nanotubes permitting their use in biomedical applications such as drug delivery.

Preparazione facile di Internamente auto-assemblato Lipid particelle stabilizzati da nanotubi di carbonio

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled ...

Preparation of Carbon Nanosheets at Room Temperature

Amphiphilic molecules equipped with a reactive, carbon-rich "oligoyne" segment consisting of conjugated carbon-carbon triple bonds self-assemble into defined aggregates in aqueous media and at the air-water interface. In the aggregated state, the oligoynes can then be carbonized under mild conditions while preserving the morphology and the embedded chemical functionalization. This novel approach provides direct access to functionalized carbon nanomaterials. In this article, we present a synthetic approach that allows us to prepare hexayne carboxylate amphiphiles as carbon-rich siblings of typical fatty acid esters through a series of repeated bromination and Negishi-type cross-coupling reactions. The obtained compounds are designed to self-assemble into monolayers at the air-water interface, and we show how this can be achieved in a Langmuir trough. Thus, compression of the molecules at the air-water interface triggers the film formation and leads to a densely packed layer of the molecules. The complete carbonization of the films at the air-water interface is then accomplished by cross-linking of the hexayne layer at room temperature, using UV irradiation as a mild external stimulus. The changes in the layer during this process can be monitored with the help of infrared reflection-absorption spectroscopy and Brewster angle microscopy. Moreover, a transfer of the carbonized films onto solid substrates by the Langmuir-Blodgett technique has enabled us to prove that they were carbon nanosheets with lateral dimensions on the order of centimeters.

We present the synthesis of an amphiphilic hexayne and its use in the preparation of carbon nanosheets at the air-water interface from a self-assembled monolayer of these reactive, carbon-rich molecular precursors.

Preparazione di carbonio nanosheets a temperatura ambiente

Amphiphilic molecules equipped with a reactive, carbon-rich "oligoyne" segment consisting of conjugated carbon-carbon triple bonds self-assemble into ...

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous solution. In a carbon nanotube/PEO105-PPO70-PEO105 (poloxamer 407) aqueous solution, the amphiphilic poloxamer 407 adsorbs onto the carbon nanotube surfaces and self-assembles into continuous layers, driven by intermolecular interactions between constituent molecules. The addition of 5-methylsalicylic acid changes the self-assembled structure from spherical-micellar to a cylindrical morphology. The fabricated poloxamer 407/carbon nanotube hybrid particles exhibit thermo-responsive structural features so that the density and thickness of poloxamer 407 layers are also reversibly controllable by varying temperature. The detailed structural properties of the poloxamer 407/carbon nanotube particles in suspension can be characterized by small-angle neutron scattering experiments and model fit analyses. The distinct curve shapes of the scattering intensities depending on temperature control or addition of aromatic additives are well described by a modified core-shell cylinder model consisting of a carbon nanotube core cylinder, a hydrophobic shell, and a hydrated polymer layer. This method can provide a simple but efficient way for the fabrication and in-situ characterization of carbon nanotube-based nano particles with a structure-tunable encapsulation.

A method for the functionalization of carbon nanotubes with structure-tunable polymeric encapsulation layers and structural characterization using small-angle neutron scattering is presented.

Funzionalizzazione di single-walled nanotubi di carbonio con termo-reversibili Block Copolimeri e caratterizzazione da piccolo angolo Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous ...

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 ...

Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a free-radical polymerization strategy to enable the modulation of the nanotube surface properties and produce supramolecular self-assembly of the nanostructures. First, a selective hydroxylation of the pristine nanotubes through a biphasic catalytically mediated oxidation reaction creates superficially distributed reactive sites at the sidewalls. The latter reactive sites are subsequently modified with methacrylic moieties using a silylated methacrylic precursor to create polymerizable sites. Those polymerizable groups can address further polymerization of styrene to produce a hybrid nanomaterial containing PS chains grafted to the nanotube sidewalls. The polymer-graft content, amount of silylated methacrylic moieties introduced and hydroxylation modification of the nanotubes are identified and quantified by Thermogravimetric Analysis (TGA). The presence of reactive functional groups hydroxyl and silylated methacrylate are confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). Polystyrene-grafted carbon nanotube solutions in tetrahydrofuran (THF) provide wall-to-wall collinearly self-assembled nanotubes when cast samples are analyzed by transmission electron microscopy (TEM). Those self-assemblies are not obtained when suitable blanks are similarly cast from analogous solutions containing non-grafted counterparts. Therefore, this method enables the modification of the nanotube anisotropic patchiness at the sidewalls which results into spontaneous auto-organization at the nanoscale.

A procedure for the synthesis of polystyrene-grafted multiwalled carbon nanotubes using successive chemical modification steps to selectively introduce the polymer chains to the sidewalls and their self-assembly via anisotropic patchiness is presented.

L'innesto Multiwalled Carbon Nanotubes con polistirolo per abilitare l'auto-assemblaggio e discromie anisotropo

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Spettroscopia di impedenza elettrochimica come uno strumento per la stima della costante tasso elettrochimica

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...