This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science and Technology (NRF-2013R1A1A1010575), and by Nano R&#38;D program through the Korea Science and Engineering Foundation funded by the Ministry of Education, Science and Technology (NRF-2012M3A7B4049863).

1. Synthesis of Vertically Aligned Multi-walled Carbon Nanotubes (VAMWCNTs)
<ol>
	<li>Preparation of wafer and deposition of catalyst layers
	<ol>
		<li>Prepare a n-type (100) Si wafer.</li>
		<li>Deposit a 250-nm-thick SiO2 layer on the Si wafer by thermal oxidation or alternative methods such as sputtering. Inject 200 sccm of O2 for 3 hr 20 min at 1,000 &#176;C in a horizontal furnace.</li>
		<li>Use bulk Al2O3 (99.9%) as a multi-sputter (RF power: 1,000 W) source and deposit a 10 nm-thick Al2O3 (99.9%) layer on the SiO2 layer. Use a slow deposition rate of 10 nm/min with a deposition pressure of 2 &#215; 10-2 mbar.</li>
		<li>Use bulk Fe (99.9%) as a source by employing an E-beam evaporator, and deposit a 1 nm-thick Fe layer on the Al2O3 layer. Use a slow deposition rate of ~0.1 nm/sec with a deposition pressure of 5 &#215; 10-6 Torr.</li>
		<li>Cut the Fe/Al2O3/SiO2/Si wafer to a 28 mm &#215; 15 mm size using a diamond scriber. 
		Note: Depending on the desirable size of the VAMWCNT array, the size of the Fe/Al2O3/SiO2/Si wafer can be varied.</li>
	</ol>
	</li>
	<li>Synthesis of MWCNT array by TCVD and preparation of free-standing MWCNT forests.
	<ol>
		<li>Place the Fe/Al2O3/SiO2/Si wafer centrally in a quartz boat that has dimensions of 120 mm &#215; 30 mm.</li>
		<li>Place the quartz boat inside the 2-inch quartz tube of the TCVD setup (Figure 1A).</li>
		<li>Inject 900 sccm of Ar gas for 10 min under ambient conditions to remove air and fill the 2-inch quartz tube with Ar.</li>
		<li>Inject 600 sccm of Ar gas and 400 sccm of H2 gas while increasing temperature in the furnace from 25 &#176;C to 750 &#176;C in 30 min.</li>
		<li>Inject 100 sccm of Ar gas and 400 sccm of H2 gas at 750 &#176;C for 10 min to formulate Fe nanoparticles as roots of MWCNTs.</li>
		<li>Inject 100 sccm of Ar gas, 368 sccm of H2 gas, and 147 sccm of ethylene (C2H4) gas at 750 &#176;C for 280 min. Simultaneously, apply Joule heating at the entrance of the quartz tube by tungsten filament (voltage: 0.8 V, current: 15 A) to promote the decomposition of C2H4 gas to act as a carbon source. These carbon sources are attached to Fe nanoparticles on Si wafers and transformed into CNTs.</li>
		<li>Stop the injection of H2 gas and C2H4 gas, and turn off the furnace. During this procedure, continuously inject 100 sccm of Ar gas until the temperature of the wafer falls below 60 &#176;C.</li>
		<li>Take out MWCNTs on the wafer. Gently separate the MWCNT array from the wafer to obtain free-standing MWCNT forests (length: 3&#8211;6 mm) (Figure 1B).</li>
	</ol>
	</li>
</ol>
2. Synthesis of Hybrid Composite of Chemical Fuel and MWCNT Films
<ol>
	<li>Preparation of chemical fuels
	<ol>
		<li>Prepare a picric acid (2,4,6-trinitro phenol) solution and sodium azide (NaN3).
		<ol>
			<li>Evaporate the picric acid solution to obtain picric acid powder (1 atm, 25 &#176;C, for 24 hr). Measure 6 g of the picric acid powder and dissolve in 100 ml of acetonitrile (262 mM).</li>
			<li>Measure 6 g of the sodium azide powder and dissolve in 100 ml of deionized (DI) water (923 mM).</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Synthesis and characterization of hybrid composites via wet impregnation
	<ol>
		<li>Measure the mass of an individual MWCNT forest with a microbalance and confirm the aligned structures of the MWCNT forest by SEM (Figure 4A). Use a voltage of 15 kV and a magnification of 1,200X. Check whether the aligned structure is maintained across the entire MWCNT forest.</li>
		<li>Add 25 &#181;l of 262 mM picric acid solution on top of the MWCNT forest to allow the fuel to penetrate the pores of the forest. Leave the sample as is for 30 min to shrink the film array, and allow the picric acid to fully penetrate the pores until all acetonitrile has evaporated from the forest (Figure 1C). 
		Note: Depending on the target ratio between the chemical fuel and MWCNT array, modify the concentration and amount of the picric acid solution.</li>
		<li>Immerse picric acid-coated MWCNT forests in 25 &#181;l of 923 mM sodium azide solution to form 2,4,6-trinitro sodium phenoxide and hydrogen azide (fuel layer) by wet impregnation. Leave the sample for 30 min until all solvents evaporate. 
		Note: Depending on the target ratio between the chemical fuel and MWCNT array, you can modify the concentration and amount of the sodium azide solution.</li>
		<li>Measure the mass of an individual hybrid composite of fuel and MWCNTs with a microbalance, and compare the final mass to calculate the mass ratio of the fuel layer and MWCNTs. 
		<img alt="Equation 1" src="/files/ftp_upload/52818/52818eq1.jpg" /> 
		where Mh and Mm are the mass of the individual hybrid composite and individual MWCNT film, respectively.</li>
		<li>Confirm the aligned structures of the hybrid composite of fuel and MWCNTs by SEM (Figure 5A). According to the manufacturer&#8217;s instructions, lower the pressure for the operating conditions, and raise magnification until the chemical fuel aggregation is clearly observed in the aligned MWCNT forest. Check the shape of fuel aggregation on MWCNTs.</li>
	</ol>
	</li>
</ol>
3. Manufacturing of Thermopower Wave Generator (Figure 2)
<ol>
	<li>Attach copper tapes to both ends of a glass slide to act as electrodes for connection with an oscilloscope, which measures the direct voltage output from the thermopower wave.</li>
	<li>Connect the copper tapes to both ends of the hybrid composite via a silver paste droplet. Leave the sample until the silver paste becomes hard and the connection is fixed.</li>
	<li>Use a multimeter to measure the electrical resistance of the hybrid composite.</li>
</ol>
4. Measurement of Thermopower Waves (Figure 3)
<ol>
	<li>Inside a polycarbonate chamber, fix the thermopower wave generator on the optical table with clamps for safety.</li>
	<li>Use alligator clips to connect the copper electrodes to the oscilloscope for the measurement of output voltage.</li>
	<li>Set up a high-speed microscopy system [components: a high speed camera (&#62; 5,000 frames/sec), macro lens (105 mm/f2.8 lens), and an LED lamp] to record combustion propagation from the generator. Place and turn on the LED lamp for clear recording with high-resolution images in front of the thermopower wave generator. Set the recording speed over 5,000 frames/sec.</li>
	<li>Place an optical pyrometer at a specific position to record the real-time changes in the temperature of the hybrid composite.</li>
	<li>Apply either laser irradiation or Joule heating to ignite the chemical fuel in the hybrid composite.
	<ol>
		<li>Focus laser (&#60;1,000 mW) at a specific position on the hybrid composite. Maintain the focus for a few seconds until combustion is initiated in the thermopower wave generator.</li>
		<li>Prepare a high-current power supply and a nickel&#8211;chrome wire. Connect the wire to a high-current power supply (operating conditions: 5 V and 3 A), and heat a nickel wire. Make gentle contact between the heated nickel wire and chemical fuel on the hybrid composite until combustion is initiated in the thermopower wave generator.</li>
	</ol>
	</li>
	<li>Turn on the measurement setup, consisting of a high-speed microscopy system, an oscilloscope, and an optical pyrometer, when a thermopower wave is launched by the generator.
	<ol>
		<li>Setup the recording frame rate (5,000 frames/sec) in the high-speed camera. Trigger recording at the start of thermopower wave propagation. Record snapshots in high-speed photographic images with the high-speed microscopy system, and extract the number of recorded frames from start to finish of thermopower wave propagation (total #number of frames).</li>
		<li>Record the voltage signal from the start to finish of thermopower wave propagation by using the oscilloscope. Extract the output voltage pulse (V).</li>
		<li>Focus the optical pyrometer at the specific position on a hybrid composite, which indicates the target areas, and measure dynamic changes in temperature (&#176;C).</li>
	</ol>
	</li>
	<li>Calculate the velocity of reaction propagation by extracting the reaction front position at individual frames in the high-speed microscopy system. 
	<img alt="Equation 2" src="/files/ftp_upload/52818/52818eq2.jpg" /> 
	where, lh is the total length of the hybrid composite, nf is the number of recorded frames from start to finish of thermopower wave propagation, and no is the recording frame rate.</li>
	<li>Extract the output voltage data from the oscilloscope and calculate the maximum peak voltage as well as the specific power from the output voltage pulse. Use the electrical resistance that was measured in Step 3.</li>
	<li>Extract the temperature change by using the optical pyrometer.</li>
</ol>

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The authors have nothing to disclose.

The protocols of thermopower wave experiments involve critical steps that enable ideal thermal wave propagation as well as electrical energy generation. First, the specific position of ignition and the corresponding reaction transfer are considerable factors in controlling energy conversion from thermopower waves. Ignition at one end of the hybrid composite launched guided combustion along the interfaces between the core materials and chemical fuels in one direction. However, ignition at any other position generated bi-d...

Chemical fuels have very high energy density and have been widely used as useful energy sources in a broad range of applications from microsystems to macrosystems.1 In particular, many researchers have endeavored to use chemical fuels as the energy source for next-generation micro/nanosystems-based technologies.2 However, owing to the difficulty in integrating energy conversion components in extremely small spaces in micro/nanodevices, there are fundamental limitations to the conversion of chemical fuels into electrical energy. Therefore, the combustion of chemical fuels has mainly been employed for the production of chemical or mechanical energy in micro/nanodevices such as nanothermites or microactuators.1,3
Thermopower waves&#8212;a newly developed energy conversion concept&#8212;have attracted considerable attention as a method for converting the chemical energy of a fuel directly to electrical energy without using any converting components.4,5 Thermopower waves can be generated using a hybrid composite of a chemical fuel and a micro/nanostructured material.5 When the chemical fuel at a certain position in a hybrid composite is ignited, chemical combustion occurs along the interface between the chemical fuel and micro/nanostructured material. Simultaneously, dynamic changes in thermal and chemical potentials across the core micro/nanostructured material result in concomitant electrical energy generation induced by charge transfer in the form of a high-output voltage pulse. It has been proven that diverse micro/nanostructured materials such as multi-walled carbon nanotubes (MWCNTs)4-6 and ZnO,7 Bi2Te3,8 Sb2Te3,9 and MnO210 micro/nanostructured materials allow hybrid composites to utilize thermopower waves and show chemical&#8211;thermal&#8211;electrical energy conversion. Specifically, core materials with a high Seebeck coefficient enable the generation of high output voltages solely from propagated combustion. However, other parameters pertaining to identical composites, such as the mixture of chemical fuels, mass ratio of fuel/core&#8211;materials, the manufacturing process, and ignition conditions critically affect the overall properties of thermopower waves.
Herein, we show how the manufacturing processes, formation of an aligned chemical fuel, and mass ratio of fuel/core materials affect thermopower wave performance. On the basis of a MWCNT array fabricated by thermal chemical vapor deposition (TCVD), we show how a hybrid composite of a chemical fuel and MWCNTs is prepared for thermopower wave energy generation. Design of the experimental setup that enables the evaluation of energy conversion is introduced along with corresponding experimental measurements for processes such as combustion propagation and direct electrical energy generation. Moreover, we demonstrate that polarity distribution&#8212;described by the dynamic output voltage and specific peak power&#8212;crucially determines the electrical energy conversion. This study will provide specific strategies to enhance energy generation, and will help in understanding the underlying physics of thermopower waves. Furthermore, the manufacturing process and experiments described here will help in extending research opportunities on thermopower waves, as well as on chemical&#8211;thermal&#8211;electrical energy conversion.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>4&#8221; n-type silicon wafer</td>
			<td>Unisill</td>
			<td>4&#8221; Si-wafer</td>
			<td></td>
		</tr>
		<tr>
			<td>Al2O3</td>
			<td>TAEWON</td>
			<td>A-1008</td>
			<td>99.9999% Purity</td>
		</tr>
		<tr>
			<td>Fe</td>
			<td>Sigma Aldrich</td>
			<td>267945</td>
			<td>99.9999% Purity</td>
		</tr>
		<tr>
			<td>Ar</td>
			<td>Seoul specialty gas</td>
			<td>Ar(N60)</td>
			<td>99.9999% Purity</td>
		</tr>
		<tr>
			<td>C2H4</td>
			<td>Seoul specialty gas</td>
			<td>C2H4</td>
			<td>99.5% Purity</td>
		</tr>
		<tr>
			<td>H2</td>
			<td>Seoul specialty gas</td>
			<td align="left"><img src="file:///C:/Users/BENSAL~1/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png" />
			<table cellpadding="0" cellspacing="0">
				<tbody>
					<tr>
						<td>H2(N60)</td>
					</tr>
				</tbody>
			</table>
			</td>
			<td>99.9999% Purity</td>
		</tr>
		<tr>
			<td>Silver paste</td>
			<td>Fujikura Kasei</td>
			<td>D-550</td>
			<td></td>
		</tr>
		<tr>
			<td>Picric acid</td>
			<td>Sigma Aldrich</td>
			<td>197378</td>
			<td>&#65310;98% Purity 
			Highly toxic</td>
		</tr>
		<tr>
			<td>Sodium azide</td>
			<td>Sigma Aldrich</td>
			<td>S2002</td>
			<td>&#65310;99.5% Purity</td>
		</tr>
		<tr>
			<td>Acetonitrile</td>
			<td>Sigma Aldrich</td>
			<td>271004</td>
			<td>99.8% Purity</td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Mastech</td>
			<td>HY3010</td>
			<td></td>
		</tr>
		<tr>
			<td>TCVD</td>
			<td>Scientech</td>
			<td>TCVD</td>
			<td></td>
		</tr>
		<tr>
			<td>Oscilloscope</td>
			<td>Tektronix</td>
			<td>DPO2004B</td>
			<td></td>
		</tr>
		<tr>
			<td>High-speed microscopy system</td>
			<td>Phantom</td>
			<td>V7.3</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation and evaluation of hybrid composites of chemical fuel and multi-walled carbon nanotubes in the study of thermopower waves

When a chemical fuel at a certain position in a hybrid composite of the fuel and a micro/nanostructured material is ignited, chemical combustion occurs along the interface between the fuel and core materials. Simultaneously, dynamic changes in thermal and chemical potentials across the micro/nanostructured materials result in concomitant electrical energy generation induced by charge transfer in the form of a high-output voltage pulse. We demonstrate the entire procedure of a thermopower wave experiment, from synthesis to evaluation. Thermal chemical vapor deposition and the wet impregnation process are respectively employed for the synthesis of a multi-walled carbon nanotube array and a hybrid composite of picric acid/sodium azide/multi-walled carbon nanotubes. The prepared hybrid composites are used to fabricate a thermopower wave generator with connecting electrodes. The combustion of the hybrid composite is initiated by laser heating or Joule-heating, and the corresponding combustion propagation, direct electrical energy generation, and real-time temperature changes are measured using a high-speed microscopy system, an oscilloscope, and an optical pyrometer, respectively. Furthermore, the crucial strategies to be adopted in the synthesis of hybrid composite and initiation of their combustion that enhance the overall thermopower wave energy transfer are proposed.

The aligned MWCNT array, as a core nanostructured material for thermopower waves, was synthesized by TCVD,11-13 as shown in Figure 4A. The diameter of as-grown MWCNTs is 20&#8211;30 nm (Figure 4B). The aligned hybrid composite of the picric acid/sodium azide/MWCNTs is shown in Figure 5A. This composite was synthesized by the wet impregnation process,14 as described in the protocol section. In order to form an interface between the chemical fuel and ...

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Preparation and Evaluation of Hybrid Composites of Chemical Fuel and Multi-walled Carbon Nanotubes in the Study of Thermopower Waves

A protocol for conducting thermopower wave experiments is presented. The synthesis of hybrid composites of a chemical fuel and micro/nanostructured material, manufacturing of a thermopower wave generator, and methods for measuring the corresponding physical phenomena are described.

When a chemical fuel at a certain position in a hybrid composite of the fuel and a micro/nanostructured material is ignited, chemical combustion occurs ...

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8.7K Views.  Korea University. A protocol for conducting thermopower wave experiments is presented. The synthesis of hybrid composites of a chemical fuel and micro/nanostructured material, manufacturing of a thermopower wave generator, and methods for measuring the corresponding physical phenomena are described. 

Video: Preparation and Evaluation of Hybrid Composites of Chemical Fuel and Multi-walled Carbon Nanotubes in the Study of Thermopower Waves

Encapsulation and Permeability Characteristics of Plasma Polymerized Hollow Particles

In this protocol, core-shell nanostructures are synthesized by plasma enhanced chemical vapor deposition. We produce an amorphous barrier by plasma polymerization of isopropanol on various solid substrates, including silica and potassium chloride. This versatile technique is used to treat nanoparticles and nanopowders with sizes ranging from 37 nm to 1 micron, by depositing films whose thickness can be anywhere from 1 nm to upwards of 100 nm. Dissolution of the core allows us to study the rate of permeation through the film. In these experiments, we determine the diffusion coefficient of KCl through the barrier film by coating KCL nanocrystals and subsequently monitoring the ionic conductivity of the coated particles suspended in water. The primary interest in this process is the encapsulation and delayed release of solutes. The thickness of the shell is one of the independent variables by which we control the rate of release. It has a strong effect on the rate of release, which increases from a six-hour release (shell thickness is 20 nm) to a long-term release over 30 days (shell thickness is 95 nm). The release profile shows a characteristic behavior: a fast release (35% of the final materials) during the first five minutes after the beginning of the dissolution, and a slower release till all of the core materials come out.

We have used plasma enhanced chemical vapor deposition to deposit thin films ranging from a few nm to several 100 nm on nano-sized particles of various materials. We subsequently etch the core material to produce hollow nanoshells whose permeability is controlled by the thickness of the shell. We characterize the permeability of these coatings to small solutes and demonstrate that these barriers can provide sustained release of the core material over several days.

In this protocol, core-shell nanostructures are synthesized by plasma enhanced chemical vapor deposition. We produce an amorphous barrier by plasma ...

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

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

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

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

Preparation and Reactivity of Gasless Nanostructured Energetic Materials

High-Energy Ball Milling (HEBM) is a ball milling process where a powder mixture placed in the ball mill is subjected to high-energy collisions from the balls. Among other applications, it is a versatile technique that allows for effective preparation of gasless reactive nanostructured materials with high energy density per volume (Ni+Al, Ta+C, Ti+C). The structural transformations of reactive media, which take place during HEBM, define the reaction mechanism in the produced energetic&#160;composites. Varying the processing conditions permits fine tuning of the milling-induced microstructures of the fabricated composite particles. In turn, the reactivity, i.e., self-ignition temperature, ignition delay time, as well as reaction kinetics, of high energy density materials depends on its microstructure. Analysis of the milling-induced microstructures suggests that the formation of fresh oxygen-free intimate high surface area contacts between the reagents is responsible for the enhancement of their reactivity. This manifests itself in a reduction of ignition temperature and delay time, an increased rate of chemical reaction, and an overall decrease of the effective activation energy of the reaction. The protocol provides a detailed description for the preparation of reactive nanocomposites with tailored microstructure using short-term HEBM method. It also describes a high-speed thermal imaging technique to determine the ignition/combustion characteristics of the energetic materials. The protocol can be adapted to preparation and characterization of a variety of nanostructured energetic composites.

This protocol describes the preparation of gasless nanostructured energetic materials (Ni+Al, Ta+C, Ti+C) using the short-term high-energy ball milling (HEBM) technique. It also describes a high-speed thermal imaging method to study the reactivity of mechanically fabricated nanocomposites. These protocols can be extended to other reactive nanostructured energetic materials.

High-Energy Ball Milling (HEBM) is a ball milling process where a powder mixture placed in the ball mill is subjected to high-energy collisions from the ...

Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing

This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints.

A straightforward procedure for ultrasonic welding of thermoplastic composite coupons for basic mechanical testing is described. Key characteristics of this ultrasonic welding process are the use of flat energy directors for simplified process preparation and the use of process data for the fast definition of optimum processing conditions.

This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ...

Preparation and 3D Tracking of Catalytic Swimming Devices

We report a method to prepare catalytically active Janus colloids that "swim" in fluids and describe how to determine their 3D motion using fluorescence microscopy. One commonly deployed method for catalytically active colloids to produce enhanced motion is via an asymmetrical distribution of catalyst. Here this is achieved by spin coating a dispersed layer of fluorescent polymeric colloids onto a flat planar substrate, and then using directional platinum vapor deposition to half coat the exposed colloid surface, making a two faced "Janus" structure. The Janus colloids are then re-suspended from the planar substrate into an aqueous solution containing hydrogen peroxide. Hydrogen peroxide serves as a fuel for the platinum catalyst, which is decomposed into water and oxygen, but only on one side of the colloid. The asymmetry results in gradients that produce enhanced motion, or "swimming". A fluorescence microscope, together with a video camera is used to record the motion of individual colloids. The center of the fluorescent emission is found using image analysis to provide an x and y coordinate for each frame of the video. While keeping the microscope focal position fixed, the fluorescence emission from the colloid produces a characteristic concentric ring pattern which is subject to image analysis to determine the particles relative z position. In this way 3D trajectories for the swimming colloid are obtained, allowing swimming velocity to be accurately measured, and physical phenomena such as gravitaxis, which may bias the colloids motion to be detected.

A method to prepare catalytically active Janus colloids that can "swim" in fluids and determine their 3D trajectories is presented.

We report a method to prepare catalytically active Janus colloids that "swim" in fluids and describe how to determine their 3D motion using fluorescence ...

Combustion Characterization and Model Fuel Development for Micro-tubular Flame-assisted Fuel Cells

Combustion based power generation has been accomplished for many years through a number of heat engine systems. Recently, a move towards small scale power generation and micro combustion as well as development in fuel cell research has created new means of power generation that combine solid oxide fuel cells with open flames and combustion exhaust. Instead of relying upon the heat of combustion, these solid oxide fuel cell systems rely on reforming of the fuel via combustion to generate syngas for electrochemical power generation. Procedures were developed to assess the combustion by-products under a wide range of conditions. While theoretical and computational procedures have been developed for assessing fuel-rich combustion exhaust in these applications, experimental techniques have also emerged. The experimental procedures often rely upon a gas chromatograph or mass spectrometer analysis of the flame and exhaust to assess the combustion process as a fuel reformer and means of heat generation. The experimental techniques developed in these areas have been applied anew for the development of the micro-tubular flame-assisted fuel cell. The protocol discussed in this work builds on past techniques to specify a procedure for characterizing fuel-rich combustion exhaust and developing a model fuel-rich combustion exhaust for use in flame-assisted fuel cell testing. The development of the procedure and its applications and limitations are discussed.

A protocol for creating a model fuel-rich combustion exhaust is developed through combustion characterization and is applied for micro-tubular flame-assisted fuel cell testing and research.

Combustion based power generation has been accomplished for many years through a number of heat engine systems. Recently, a move towards small scale power ...

Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent

The aim of this work is to present a zero-waste process for storing CO2 in a stable and benign mineral form while producing zeolitic minerals with sufficient heavy metal adsorption capacity. To this end, blast furnace slag, a residue from iron-making, is utilized as the starting material. Calcium is selectively extracted from the slag by leaching with acetic acid (2 M CH3COOH) as the extraction agent. The filtered leachate is subsequently physico-chemically purified and then carbonated to form precipitated calcium carbonate (PCC) of high purity (&lt;2 wt% non-calcium impurities, according to ICP-MS analysis). Sodium hydroxide is added to neutralize the regenerated acetate. The morphological properties of the resulting calcitic PCC are tuned for its potential application as a filler in papermaking. In parallel, the residual solids from the extraction stage are subjected to hydrothermal conversion in a caustic solution (2 M NaOH) that leads to the predominant formation of a particular zeolitic mineral phase (detected by XRD), namely analcime (NaAlSi2O6&#8729;H2O). Based on its ability to adsorb Ni2+, as reported from batch adsorption experiments and ICP-OES analysis, this product can potentially be used in wastewater treatment or for environmental remediation applications.

A protocol for the parallel production of precipitated calcium carbonate and zeolitic material from blast furnace slag via mineral carbonation and alkaline hydrothermal conversion, respectively, is presented. The performance of the zeolitic material towards nickel adsorption is tested.

The aim of this work is to present a zero-waste process for storing CO2 in a stable and benign mineral form while producing zeolitic minerals with ...

Production and Characterization of Vacuum Deposited Organic Light Emitting Diodes

A method for producing simple and efficient thermally-activated delayed fluorescence organic light-emitting diodes (OLEDs) based on guest-host or exciplex donor-acceptor emitters is presented. With a step-by-step procedure, readers will be able to repeat and produce OLED devices based on simple organic emitters. A patterning procedure allowing the creation of personalized indium tin oxide (ITO) shape is shown. This is followed by the evaporation of all layers, encapsulation and characterization of each individual device. The end goal is to present a procedure that will give the opportunity to repeat the information presented in cited publication but also using different compounds and structures in order to prepare efficient OLEDs.

A protocol for the production of simple structured organic light-emitting diodes (OLEDs) is presented.

A method for producing simple and efficient thermally-activated delayed fluorescence organic light-emitting diodes (OLEDs) based on guest-host or exciplex ...

Film Control to Study Contributions of Waves to Droplet Impact Dynamics on Thin Flowing Liquid Films

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous studies on flowing liquid films have neglected the contributions of spatial structures of waves to the impact outcome, while this has recently been shown to have a significant influence on the drop impact dynamics. In this report, we outline a step-by-step procedure to investigate the effect of periodic inlet forcing of a flowing liquid film leading to the production of spatiotemporally regular wave structures on drop impact dynamics. A function generator in connection with a solenoid valve is used to excite these spatiotemporally regular wave structures on the film surface while the impact dynamics of uniform-sized droplets are captured using a high-speed camera. Three distinct regions are then studied; viz. the capillary wave region preceding the large wave peak, the flat film region, and the wave hump region. The effects of important dimensionless quantities such as film Reynolds, drop Weber and Ohnesorge numbers parameterized by the film flow rate, drop speed, and drop size are also examined. Our results show interesting, hitherto undiscovered dynamics brought about by this application of film inlet forcing of the flowing film for both low and high inertia drops.

A protocol to study the contributions of waves to droplet impact dynamics on flowing liquid films is presented.

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous ...

Fabrication and Design of Wood-Based High-Performance Composites

Delignified densified wood is a new promising and sustainable material that possesses the potential to replace synthetic materials, such as glass fiber reinforced composites, due to its excellent mechanical properties. Delignified wood, however, is rather fragile in a wet state, which makes handling and shaping challenging. Here we present two fabrication processes, closed-mold densification and vacuum densification, to produce high-performance cellulose composites based on delignified wood, including an assessment of their advantages and limitations. Further, we suggest strategies for how the composites can be re-used or decomposed at the end-of-life cycle. Closed-mold densification has the advantage that no elaborate lab equipment is needed. Simple screw clamps or a press can be used for densification. We recommend this method for small parts with simple geometries and large radii of curvature. Vacuum densification in an open-mold process is suitable for larger objects and complex geometries, including small radii of curvature. Compared to the closed-mold process, the open-mold vacuum approach only needs the manufacture of a single mold cavity.

Delignified densified wood represents a new promising lightweight, high-performance and bio-based material with great potential to partially substitute natural fiber reinforced- or glass fiber reinforced composites in the future. We here present two versatile fabrication routes and demonstrate the possibility to create complex composite parts.

Delignified densified wood is a new promising and sustainable material that possesses the potential to replace synthetic materials, such as glass fiber ...