The authors acknowledge funding from the Singapore Ministry of Education Tier 2 Research Fund (project MOE2013-T2-2-002) for this project.

1. Preparation Procedure for 1,3,5-Triphenylbenzene (1)
<ol>
	<li>Place a mixture of acetophenone (4.0 g, 33.3 mmol) and 100 ml of absolute ethanol into a round bottom three neck 250 ml flask equipped with magnetic stirrer, reflux condenser, nitrogen inlet, bubbler, dropping funnel and thermometer. Add silicon tetrachloride (11.9 g, 8.0 ml, 70.2 mmol, 2.1 eq.) to the mixture in one portion at 0 &#176;C under nitrogen using the dropping funnel.</li>
	<li>Observe the evolution of gaseous hydrogen chloride for 10 min. Then stir the reaction mixture at 40 &#176;C for 20 hr.</li>
	<li>Cool down the reaction mixture to 23 &#176;C and pour in 200 g of water mixed with ice (1:1 mass ratio).</li>
	<li>Extract the resulting mixture with dichloromethane (2 x 100 ml) using an extraction funnel.</li>
	<li>Wash the combined extracts once with saturated NaCl solution (100 ml), and dry over 15 g of anhydrous MgSO4. Filter the liquid part off and then concentrate using a rotary evaporator.</li>
	<li>Purify the product via recrystallization from ethanol (dissolution in minimal amount of ethanol followed by partial evaporation of the solvent, keeping at 6 &#176;C overnight, and rapid filtration) to obtain 2.2 g (yield 63%) of 1,3,5-triphenylbenzene (1) as pale yellow crystals. 
	Note: 1H-NMR (400 MHz, CDCl3): &#948;= 7.41 (m, 3H), 7.50 (m, 6H), 7.72 (d, 6H, J = 7.33Hz), 7.80 (s, 3H). 13C-NMR (400 MHz, CDCl3): &#948;= 125.21, 127.39, 127.57, 128.88, 141.18, 142.38.</li>
</ol>
2. LiSES Prepared with 1,3,5-Triphenylbenzene
<ol>
	<li>Preparation of 1,3,5-triphenylbenzene-based LiSES 
	NOTE: 1,3,5-triphenylbenzene used in this paper was synthesized as per procedure described above. The 1,3,5-triphenylbenzene -based LiSES are denoted by LixTPB(THF)24.7 where x denotes the Li:PAH molar ratio and TPB denotes 1,3,5-triphenylbenzene. Prepare LixTPB(THF)24.7 inside an argon-filled glovebox at ambient temperature via the following steps:
	<ol>
		<li>Measure out well defined quantities of metallic Li, THF and TPB separately inside the glovebox to achieve the target molar composition of LixTPB(THF)24.7 for x = 1, 2, 3, and 4. Use 41.6 mg, 83.3 mg, 124.9 mg, 166.6 mg of Li for x = 1, 2, 3 and 4 respectively.</li>
		<li>For each of the four LiSES samples to be prepared, dissolve 1.84 g of TPB in 12 ml of THF inside four separate glass bottles to form 12 ml of colorless solutions of TPB(THF)24.7 for each bottle. Use a 0.5 M 1,3,5-triphenylbenzene in all the solutions.</li>
		<li>Add the weighed metallic Li foils to the four bottles and seal the bottles with Parafilm.</li>
		<li>Stir the mixture in each bottle overnight using a glass-coated magnetic stirrer to ensure the complete dissolution of metallic Li.</li>
	</ol>
	</li>
	<li>Conductivity Measurements
	<ol>
		<li>Carry out all conductivity measurements using a standard conductivity cell probe based on the four-electrode technique. Attach the cell probe to a meter. The probe has a secondary function to measure the solution&#39;s temperature at the same time and display both conductivity and temperature measurements.</li>
		<li>Prior to measurements, calibrate the meter using 50 ml of standard 0.01 M aqueous KCl solution provided by the conductivity probe&#39;s manufacturer outside the glovebox.</li>
		<li>Carry out all the conductivity measurements for 1,3,5-triphenylbenzene-based LiSES, LixTPB(THF)24.7 for x = 1, 2, 3, 4 inside the glovebox.</li>
		<li>For each of these LiSES, pour out the sample into a short glass cylinder and immerse the probe into the solution. Record the conductivity measurement over a period of one to two hours till each sample returns to an ambient temperature. The time taken for each sample to return to ambient temperature is ~1-2 hr. The probe will remain immersed in the sample for the entire duration of conductivity measurement.</li>
	</ol>
	</li>
</ol>
3. Corannulene
<ol>
	<li>Preparation of corannulene-based LiSES 
	NOTE: The corannulene used in this paper was synthesized at the School of Physical and Mathematical Sciences, NTU using a multistep literature procedure.9 The corannulene-based LiSES are denoted by LixCor(THF)247 where x denotes the Li:PAH molar ratio and Cor denotes the corannulene. Prepare LixCor(THF)247 inside an argon-filled glovebox at ambient temperature via the following steps:
	<ol>
		<li>Measure out well defined quantities of metallic Li, THF and Cor separately inside the glovebox to achieve the target molar composition of LixCor(THF)247 for x = 1, 2, 3, 4 and 5. Use 4.2 mg, 8.3 mg, 12.5 mg, 16.6 mg and 20.8 mg of Li for x = 1, 2, 3, 4 and 5 respectively.</li>
		<li>Next, for each of the five LiSES samples (x = 1, 2, 3, 4 and 5) to be prepared, dissolve 0.15 g of Cor in 12 ml of THF inside five separate glass bottles to form 12 ml of colorless solution of Cor(THF)247 in each bottle. Use a corannulene concentration of 0.05 M).</li>
		<li>Next, add the weighed metallic Li foils to the five bottles of Cor(THF)247 and seal the bottles with Parafilm.</li>
		<li>Stir the mixture in each bottle overnight using a glass-coated magnetic stirrer to ensure the complete dissolution of the metallic lithium.</li>
	</ol>
	</li>
	<li>Conductivity Measurements
	<ol>
		<li>For conductivity versus temperature measurements, remove each of the five bottles containing LixCor(THF)247 for x = 1, 2, 3, 4 and 5 individually from the glovebox, wrap it with an additional layer of para-film and immerse it inside an insulated Styrofoam container filled with dry ice. 
		NOTE: The LiSES samples did not come into contact with either moisture or oxygen while outside the glovebox because the bottles were sealed.</li>
		<li>Cool each bottle down to about 10 &#176;C by keeping each bottle immersed in the dry ice for about 30 min before being transferred back into the glovebox for conductivity measurements.</li>
		<li>Purge the ante-chamber of the glovebox at least 5 times for each cooled sample to ensure that no traces of water of condensation accompany the bottle back into the glovebox.</li>
		<li>Similar to the manner in which conductivity versus temperature measurements were collected for naphthalene-based LiSES samples1, measure the conductivity of LixCor(THF)247 (x = 1, 2, 3, 4, 5) over a period of one to two hours till each sample returned to ambient temperature. The probe will remain immersed in the sample for the entire duration of conductivity measurement.</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>

The authors have nothing to disclose.

For the 1,3,5-triphenylbenzene-based LiSES, a sample with a light color shows that it has a low concentration of solvated electrons. LixTPB(THF)24.7 (for x = 1, 2, 3, 4) demonstrates a behavior in its conductivity versus x similar to that seen for LiSES made from biphenyl and naphthalene1, 2.There is an initial increase in conductivity with increase of Li:PAH ratio from 1 to 2 and a subsequent decrease in conductivity upon further increasing the molar ratio to 3 and 4, with condu...

Lithium solvated electron solutions (LiSES) prepared using simple two-ring polyaromatic hydrocarbons (PAH) such as biphenyl and naphthalene can potentially be utilized as liquid anodes in refuelable lithium cells1-7. In the LiSES, these simple PAH molecules served as the electron receptors for solvated electrons from dissolved metallic lithium.
Progressing from these two-ring systems, the authors have since then carried out conductivity measurement studies on LiSES which are prepared using more complex PAHs, starting with the group of cyclopenta-2,4-dienone derivatives8. These PAHs include larger PAHs (&#62;two benzene rings) and PAHs with substituents incorporated into their aromatic rings. A larger PAH molecule with more than two rings is expected to accommodate more lithium atoms per PAH molecule than either biphenyl or naphthalene thus resulting in LiSES with a higher energy density. The objective of introducing substituents into PAHs is to make the PAH accept electrons more readily and become more stable as polyanions in LiSES.
As part of ongoing efforts to develop LiSES with higher energy density, this paper will report on the characterization of LiSES prepared from corannulene made by the literature procedure9 as well as 1,3,5-triphenylbenzene, TPB synthesized by a slightly modified literature 10. 1,3,5-triphenylbenzene, as shown in Figure 1(1), can be classified as a biphenyl derivative with two additional phenyl rings at positions 3 and 5 of the same ring. Since this molecule has four benzene rings, it should uptake 4 atoms of Li per molecule, which is more than for biphenyl (maximum 2.5 mole equivalents of Li per PAH in 0.5 M solution) and naphthalene (&#60;2.5 mole equivalents of lithium per molecule).
Corannulene is a five-ring PAH arranged into a bowl shape as shown in Figure 1(2). Zabula et al.11 have demonstrated the feasibility of dissolving metallic lithium in a solution of corannulene/tetrahydrofuran (THF) to form a solution with five Li+ ions sandwiched between two stable tetraanions of corannulene.
<img alt="Figure 1" src="/files/ftp_upload/54366/54366fig1.jpg" /> 
Figure 1: The molecular structures of 1,3,5-triphenylbenzene (1) and corannulene (2). 1,3,5-triphenylbenzene is classified as a biphenyl derivative with two additional phenyl rings at positions 3 and 5 of the same ring. Corannulene is a five-ring PAH with its five benzene rings arranged into a bowl shape. <a href="https://www.jove.com/files/ftp_upload/54366/54366fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Thus, both 1,3,5-triphenylbenzene and corannulene are potential candidates for high energy density LiSES.

<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

The authors report on conductivity studies carried out on lithium solvated electron solutions (LiSES) prepared using two types of polyaromatic hydrocarbons (PAH), namely 1,3,5-triphenylbenzene and corannulene, as electron receptors. The solid PAHs were first dissolved in tetrahydrofuran (THF) to form a solution. Metallic lithium was then dissolved into these PAH/THF solutions to yield either blue or greenish blue solutions, colors which are indicative of the presence of solvated electrons. Conductivity measurements at ambient temperature carried out on 1,3,5-triphenylbenzene-based LiSES, denoted by LixTPB(THF)24.7 (x = 1, 2, 3, 4), showed an increase of conductivity with increase of Li:PAH ratio from x = 1 to 2. However, the conductivity gradually decreased upon further increasing the ratio. Indeed the conductivity of LixTPB(THF)24.7 for x = 4 is even lower than for x = 1. Such behavior is similar to that of the previously reported LiSES prepared from biphenyl and naphthalene. Conductivity versus temperature measurements on corannulene-based LiSES, denoted by LixCor(THF)247 (x = 1, 2, 3, 4, 5), showed linear relationships with negative slopes, indicating a metallic behavior similar to biphenyl and naphthalene-based LiSES.

Reaction between various amounts of lithium and mixtures of 1,3,5-triphenylbenzene with THF gives greenish blue or deep blue colored solutions as shown in Figure 2. A light color indicates that the particular sample of LiSES has a low concentration of solvated electrons. 1,3,5-triphenylbenzene demonstrates increase of conductivity with increase of Li:PAH ratio from 1 to 2 in 0.5 M THF solution (Table 1). However, conductivity value gradually decreases upon further increasing the molar ra...

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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