Name: testing of nanoparticle release from a composite containing nanomaterial using a chamber system
Uploaded: 2016-11-22T13:00:00
Description: Watch this Scientific Journal Video about Testing of Nanoparticle Release from a Composite Containing Nanomaterial Using a Chamber System at JoVE.com

This research was supported by the "Development of technologies for safety evaluation and standardization of nanomaterials and nanoproducts" (10059135)" through the Korea Evaluation Institute of Industrial Technology by the Korean Ministry of Trade, Industry &amp; Energy.

1. Preparation of Instruments and Specimens
<ol>
	<li>Abrasor
	<ol>
		<li>Based on an abrasion tester, use an abrasor with one specimen rotation stage (140 mm diameter), two abrasion wheel holders, and a rotation speed of 30 - 80 rpm.</li>
		<li>Use a weight to secure the abrasion wheel to the abrasion wheel holder, which also applies load to the test specimen.</li>
		<li>Install an additional air inlet to provide better suspension for the abrased particles, as shown in Figure 3. Use a...

<ol>
	<li>Froggett, S. J., Clancy, S. F., Boverhof, D. R., Canady, R. 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+review+and+perspectives+of+existing+research+on+the+release+of+nanomaterials+from+solid+nanocomposites.">A review and perspectives of existing research on the release of nanomaterials from solid nanocomposites.</a> Part Fibre Toxicol. 11, (2014).</li><li>Kingston, C., Zepp, R., Andrady, A., Boverhof, D., Fehir, R., Hawkins, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Release+characteristics+of+selected+carbon+nanotube+polymer+composites.">Release characteristics of selected carbon nanotube polymer composites.</a> Carbon. 68, 33-57 (2014).</li><li>Kaiser, D., Stefaniak, A., Scott, K., Nguyen, T., Schutz, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Methods for the Measurement of Release of MWCNTs from MWCNT-Polymer Composites, NIST. , (2014).</li><li>Nowack, B., David, R. M., Fissan, H., Morris, H., Shatkin, J. A., Stintz, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Potential+release+scenarios+for+carbon+nanotubes+used+in+composites.">Potential release scenarios for carbon nanotubes used in composites.</a> Environ. Int. 59, 1-11 (2013).</li><li>Kim, E., Lee, J. H., Kim, J. K., Lee, G. H., Ahn, K., Park, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Case+Study+on+Risk+Evaluation+of+Silver+Nanoparticle+Exposure+from+Antibacterial+Sprays+Containing+Silver+Nanoparticles.">Case Study on Risk Evaluation of Silver Nanoparticle Exposure from Antibacterial Sprays Containing Silver Nanoparticles.</a> J of Nanomaterial. , 346586 (2015).</li><li>Kim, E., Lee, J. H., Kim, J. K., Lee, G. H., Ahn, K., Park, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Case+study+on+risk+evaluation+of+printed+electronics+using+nanosilver+ink.">Case study on risk evaluation of printed electronics using nanosilver ink.</a> Nano Convergence. , (2016).</li><li>Vorbau, M., Hillemann, L., Stintz, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+for+the+characterization+of+the+abrasion+induced+nanoparticle+release+into+air+from+surface+coatings.">Method for the characterization of the abrasion induced nanoparticle release into air from surface coatings.</a> J. Aerosol Sci. 40, 209-217 (2009).</li><li>Golanski, L., Gaborieau, A., Guiot, A., Uzu, G., Chatenet, J., Tardif, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+abrasion-induced+nanoparticle+release+from+paints+into+liquids+and+air.">Characterization of abrasion-induced nanoparticle release from paints into liquids and air.</a> J. Phys. Conf. Ser. 304, 012062 (2011).</li><li>Wohlleben, W., Brill, S., Meier, M. W., Mertler, M., Cox, G., Hirth, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+lifecycle+of+nanocomposites:+Comparing+released+fragments+and+their+in-vivo+hazards+from+three+release+mechanisms+and+four+nanocomposites.">On the lifecycle of nanocomposites: Comparing released fragments and their in-vivo hazards from three release mechanisms and four nanocomposites.</a> Small. 7, 2384-2395 (2011).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> ISO 7784-1, Paints and varnishes -- Determination of resistance to abrasion -- Part 1: Rotating abrasive-paper-covered wheel method. , (1997).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> ISO 5470-1, Rubber- or plastics-coated fabrics -- Determination of abrasion resistance -- Part 1: Taber abrader. , (1999).</li><li>Schlagenhauf, L., Chu, B. T. T., Buha, J., N&#252;sch, F., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Release+of+carbon+nanotubes+from+an+epoxy-based+nanocomposites+during+an+abrasion+process.">Release of carbon nanotubes from an epoxy-based nanocomposites during an abrasion process.</a> Enviorn. Sci. Tech. 46, 7366-7372 (2012).</li><li>Bello, D., Wardle, B. L., Yamamoto, N., deVilloria, R. G., Garcia, E. J., Hart, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exposure+to+nanoscale+particles+and+fibers+during+machining+of+hybrid+advanced+composites+containing+carbon+nanotubes.">Exposure to nanoscale particles and fibers during machining of hybrid advanced composites containing carbon nanotubes.</a> J. Nanopart. Res. 11, 231-249 (2009).</li><li>Cena, L. G., Peters, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+and+control+of+airborne+particles+emitted+during+production+of+epoxy/carbon+nanotube+nanocomposites.">Characterization and control of airborne particles emitted during production of epoxy/carbon nanotube nanocomposites.</a> J. Occup. Environ. Hyg. 8, 86-92 (2011).</li></ol>

The most critical steps when conducting the nanorelease test from nanocomposite materials using an abrasion test were: 1) using a chamber system made of stainless steel with a neutralizer to remove the electrostatic charge generated by abrasion and reduce the deposition of particles on the chamber walls; 2) supplying additional air to provide better particle suspension; and 3) sampling the released particles and online monitoring using a CPC and OPC from the outlet that contained a mixer consisting of three perforated pl...

Nanomaterial exposure has mostly been studied in relation to workers in workplaces manufacturing, handling, fabricating, and packaging nanomaterials, while consumer exposure has not been studied extensively. A recent analysis of the environmental and health literature database created by the International Council of Nanotechnology (ICON) also indicated that most nanomaterial safety research has focused on hazards (83%) and potential exposure (16%), with the release from nanocomposites, representing consumer exposure, only representing 0.8% 1. Thus, very little is known about consumer exposure to nanomaterials.
Nanoparticle release has been used to estimate consumer exposure in simulation studies, including the abrasion and weathering of nanocomposites, washing textiles, or dustiness testing methods, such as the rotating drum method, vortex shaking method, and other shaker methods 2-3. Plus, several international attempts, such as the ILSI (International Life Science Institute) nanorelease and EU NanoReg, have been made to develop technology to understand the release of nanomaterials used in consumer products. The ILSI nanorelease consumer product launched in 2011 represents a life-cycle approach to nanomaterial release from consumer products, where phase 1 involves nanomaterial selection, phase 2 covers evaluation methods, and phase 3 implements interlaboratory studies. Several monographs and publications on the safety of nanomaterials in consumer products have also been published 4-6.
Meanwhile, NanoReg represents a common European approach to the regulatory testing of manufactured nanomaterials and provides a program of methods for use in simulation approaches to nanorelease from consumer products 2. ISO TC 229 is also trying to develop standards relevant to consumer safety and submit a new working item proposal for consumer safety. The OECD WPMN (working party on nanomaterials), especially SG8 (steering group on exposure assessment and exposure mitigation), recently conducted a survey on the direction of future work, especially consumer and environmental exposure assessment. Therefore, in light of these international activities, the Korean Ministries of Trade, Industry and Energy launched a tiered project in 2013 focused on the &#34;Development of technologies for the safety evaluation and standardization of nanomaterials and nanoproducts&#34;. Plus, several consumer safety-relevant studies to standardize nanomaterial release from consumer products have also been published 7-8.
An abrasion test is one of the simulation approaches included in the ILSI nanorelease and NanoReg 2-3 for determining the potential emission level of nanoparticles from different commercial composite products. The mass weight loss is deduced based on the difference in the specimen weight before and after abrasion using an abrasor. The nanocomposite sample is abraded at a constant speed, a sampler sucks up the aerosol, and the particles are then analyzed using particle counting devices, such as a Condensation Particle Counter (CPC) or optical particle counter (OPC), and collected on a TEM (transmission electron microscopy) grid or membrane for further visual analysis. However, conducting an abrasion test for nanocomposite materials requires a consistent nanoparticle release, which is difficult due to particle charging as a result of abrasion and when the particle sampling is conducted near the emission point 2-3, 9-11.
Accordingly, this paper presents a chamber system as a new method for evaluating nanomaterial release in the case of abrasion of nanocomposite materials. When compared with other abrasion and simulation tests, the proposed chamber system provides consistent nanoparticle release data in the case of abrasion. Moreover, this new test method has been used widely in the field of indoor air quality and semi-conduct industry as total particle number counting method 12, 13. Therefore, it is anticipated that the proposed method can be developed into a standardized method for testing nanoparticle release from consumer products containing nanomaterials.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Foamex</td>
			<td>Taeyoung, R. of Korea</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MWCNT (multiwalled carbon nanotube) composite</td>
			<td>Hanwha, Incheon, R. of Korea</td>
			<td></td>
			<td>2% MWCNTs in low density polyethylene</td>
		</tr>
		<tr>
			<td>Abrasion Paper</td>
			<td>Derfos, R. of Korea</td>
			<td>#100</td>
			<td>100 grit sand paper</td>
		</tr>
		<tr>
			<td>Condensation Particle Counter (CPC)</td>
			<td>TSI Inc, Shoreview, MN</td>
			<td>UCPC 3775</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical Paritcle Counter (OPC)</td>
			<td>Grimm, Ainring, Germany</td>
			<td>1.109</td>
			<td></td>
		</tr>
		<tr>
			<td>Mini Particle Sampler</td>
			<td>Ecomesure, Saclay, France</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Quantifoil Holey Carbon Film</td>
			<td>TED PELLA Inc. USA</td>
			<td>1.2/1.3</td>
			<td></td>
		</tr>
		<tr>
			<td>Filter Holder</td>
			<td></td>
			<td></td>
			<td>custom made</td>
		</tr>
		<tr>
			<td>Polycarbonate Filter&#160;</td>
			<td>Millipore, USA</td>
			<td>CAT No. GTTP02500</td>
			<td></td>
		</tr>
		<tr>
			<td>Soft X-ray Ionizer (Neutralizer)</td>
			<td>SUNJE, R. of Korea</td>
			<td>SXN-05U</td>
			<td></td>
		</tr>
		<tr>
			<td>Field Emission-Scanning Electron Microscope (FE-SEM)</td>
			<td>Hitachi</td>
			<td>S-4300</td>
			<td></td>
		</tr>
	</tbody>
</table>

testing of nanoparticle release from a composite containing nanomaterial using a chamber system

With the rapid development of nanotechnology as one of the most important technologies in the 21st century, interest in the safety of consumer products containing nanomaterials is also increasing. Evaluating the nanomaterial release from products containing nanomaterials is a crucial step in assessing the safety of these products, and has resulted in several international efforts to develop consistent and reliable technologies for standardizing the evaluation of nanomaterial release. In this study, the release of nanomaterials from products containing nanomaterials is evaluated using a chamber system that includes a condensation particle counter, optical particle counter, and sampling ports to collect filter samples for electron microscopy analysis. The proposed chamber system is tested using an abrasor and disc-type nanocomposite material specimens to determine whether the nanomaterial release is repeatable and consistent within an acceptable range. The test results indicate that the total number of particles in each test is within 20% from the average after several trials. The release trends are similar and they show very good repeatability. Therefore, the proposed chamber system can be effectively used for nanomaterial release testing of products containing nanomaterials.

Abrasion Test Repeatability Using Chamber System
The total particle numbers were consistent for 8 abrasion tests, as shown in Table 3. The CPC measured an average of 3.67 x109 particles, while the OPC counted an average of 1.98 x 109 particles (&#62; 0.3 &#181;m). The deviations were within 20%, which represented a consistent release of particles during abrasion.
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Watch this Scientific Journal Video about Testing of Nanoparticle Release from a Composite Containing Nanomaterial Using a Chamber System at JoVE.com

Testing of Nanoparticle Release from a Composite Containing Nanomaterial Using a Chamber System

Nanoparticle release is tested using a chamber system that includes a condensation particle counter, an optical particle counter and sampling ports to collect filter samples for microscopy analysis. The proposed chamber system can be effectively used for nanomaterial release testing with a repeatable and consistent data range.

With the rapid development of nanotechnology as one of the most important technologies in the 21st century, interest in the safety of consumer products ...

The overall goal of this procedure is to evaluate nanomaterial release in the case of abrasion of nanocomposite materials. This method can help answer key questions in the occupation hygiene field such as risk assessment and workplace environment. The main advantage of this technique is that it allows one to evaluate nanomaterial release in the case of abrasion of nanocomposite materials.For this experiment, use an abraser with a 140 millimeter diameter specimen rotation stage, which can rotate 30 to 80 rotations per minute, and two abrasion wheel holders. Install a disk shaped specimen on the specimen rotation stage. Use a weight to secure the abrasion wheels, that are wrapped with 100 grit sandpaper, to the abrasion wheel holder which also applies load to the test specimen.Use stainless steel for the chamber walls to avoid particle deposition due to electrostatic force. Locate the air inlet and outlet in the upper and lower part of the chamber respectively. Place the abraser inside of the chamber, and install an additional air inlet in the abraser that is 15 millimeters above and 40 millimeters away from the center of the test specimen to provide better suspension for the abrased particles.Next, locate the neutralizer 28 centimeters away from the center of the test specimen at a 45 degree angle to reduce the electrostatic particle deposition on the chamber walls. Install a CPC and OPC at the outlet of the chamber to measure the particle number concentration and particle size distribution respectively. Operate the blower installed at the outlet of the chamber at a flow rate of 50 liters per minute.Following this, supply 25 liters per minute of additional particle-free suspension air using an air compressor through the additional air inlet. Check the background particle number concentration inside the chamber to reach an average particle number concentration for one hour of below one number per cubic centimeter using the condensation particle counter. Next, operate the specimen rotation stage of the abraser using a step motor that rotates the specimen rotation stage at 72 rotations per minute with 1000 rotations.Measure and record the released particle number concentration and particle size distribution using the CPC and OPC respectively. Now, sample the released particles using a particle sampler containing filter media or a TEM grid. Stop the measurement and sampling when the particle number concentration reaches below 0.1%of the peak particle number concentration.After saving the data, remove the samples from the instrument. The typical change in particle number concentration during the abrasion test is shown here. During the abrasion an increase in particle number concentration was observed followed by a decrease after abrasion.The CPC measured an average of 3.67 times 10 to the nine particles, and the deviations were within 20%which represented a consistent release of particles during abrasion. The OPC measured an average of 1.98 times 10 to the nine particles, and the deviations were within 20%which represented a consistent release of particles during abrasion. After abrasion the original test specimens lost approximately 0.6 grams or 1.56%The total particle number release from nanocomposite containing carbon nanotubes by the abrasion test is shown here.The nanocomposite containing carbon nanotubes released 12.6%more condensation particles and 1.9%more optical particles than the control composite. Most of the particles were torn due to abrasion, and field emission scanning electron microscopy revealed no free carbon nanotube structures from the nanocomposite containing 2%carbon nanotubes in the filter samples or many particle sampler samples after abrasion. After watching this video, you should have a good understanding of how evaluate nanomaterial release in the case of abrasion of nanocomposite materials.

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Engineering

Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via stereotactic radiotherapy where positioning accuracy allows delivering very high doses per fraction in a small volume of the patient. Dosimetric measurements on medical accelerators are conventionally realized using air-filled ionization chambers. However, in small beams these are subject to nonnegligible perturbation effects. This study focuses on liquid ionization chambers, which offer advantages in terms of spatial resolution and low fluence perturbation. Ion recombination effects are investigated for the microLion detector (PTW) used with the Cyberknife system (Accuray). The method consists of performing a series of water tank measurements at different source-surface distances, and applying corrections to the liquid detector readings based on simultaneous gaseous detector measurements. This approach facilitates isolating the recombination effects arising from the high density of the liquid sensitive medium and obtaining correction factors to apply to the detector readings. The main difficulty resides in achieving a sufficient level of accuracy in the setup to be able to detect small changes in the chamber response.

A growing number of radiation therapy devices offer the advantage of delivering the dose through very small beams to the tumor, allowing for increased conformity and higher doses per fraction. Many different detectors can be used for the dosimetry of these small fields. In the present study, the effect of ion recombination is investigated for a liquid ionization chamber using a stereotactic radiation therapy system.

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via ...

Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using visible light irradiation with plasmonic nanoparticles. The plasmonic nanoparticle is used to improve the reduction efficiency of GO. It only takes 30 min&#160;at RT by illuminating the solutions with Xe-lamp, the r-GO solutions can be obtained by completely removing gold nanoparticles through simple centrifugation step. The spherical gold nanoparticles (AuNPs) as compared to the other nanostructures is the most suitable plasmonic nanostructure for r-GO preparation. The reduced graphene oxide prepared using visible light and AuNPs was equally qualitative as chemically reduced graphene oxide, which was supported by various analytical techniques such as UV-Vis spectroscopy, Raman spectroscopy, powder XRD and XPS. The reduced graphene oxide prepared with visible light shows excellent quenching properties over the fluorescent molecules modified on ssDNA and excellent fluorescence recovery for target DNA detection. The r-GO prepared by recycled AuNPs is found to be of same quality with that of chemically reduced r-GO. The use of visible light with plasmonic nanoparticle demonstrates the good alternative method for r-GO synthesis.

A simple protocol for the preparation of reduced graphene oxide using visible light and plasmonic nanoparticle is described.

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using ...

Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus have potential applications in nonlinear optics, which requires extraordinary optical intensity. One of the most studied nonlinearities in plasmonics is nonlinear absorption, including saturation and reverse saturation behaviors. Although scattering and absorption in nanoparticles are closely correlated by the Mie theory, there has been no report of nonlinearities in plasmonic scattering until very recently. 
Last year, not only saturation, but also reverse saturation of scattering in an isolated plasmonic particle was demonstrated for the first time. The results showed that saturable scattering exhibits clear wavelength dependence, which seems to be directly linked to the localized surface plasmon resonance (LSPR). Combined with the intensity-dependent measurements, the results suggest the possibility of a common mechanism underlying the nonlinear behaviors of scattering and absorption. These nonlinearities of scattering from a single gold nanosphere (GNS) are widely applicable, including in super-resolution microscopy and optical switches. 
In this paper, it is described in detail how to measure nonlinearity of scattering in a single GNP and how to employ the super-resolution technique to enhance the optical imaging resolution based on saturable scattering. This discovery features the first super-resolution microscopy based on nonlinear scattering, which is a novel non-bleaching contrast method that can achieve a resolution as low as l/8 and will potentially be useful in biomedicine and material studies.

Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy.

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus ...

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 ...

A System to Create Stable Nanoparticle Aerosols from Nanopowders

Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring minimal amounts of test materials (min. 200 mg), for studying powder aerosolization behavior and aerosol properties. The aerosolization procedure follows the concept of the fluidized-bed process, but occurs in the modified volume of a V-shaped aerosol generator. The airborne particle number concentration is adjustable by controlling the air flow rate. The system supplied stable aerosol generation rates and particle size distributions over long periods (0.5-2 hr and possibly longer), which are important, for example, to study aerosol behavior, but also for toxicological studies. Strict adherence to the operating procedures during the aerosolization experiments ensures the generation of reproducible test results. The critical steps in the standard protocol are the preparation of the material and setup, and the aerosolization operations themselves. The system can be used for experiments requiring stable aerosol concentrations and may also be an alternative method for testing dustiness. The controlled aerosolization made possible with this setup occurs using energy inputs (may be characterized by aerosolization air velocity) that are within the ranges commonly found in occupational environments where nanomaterial powders are handled. This setup and its operating protocol are thus helpful for human exposure and risk assessment.

We designed and developed an effective nanopowder aerosolization setup and operating protocol. The system generated nanoparticle aerosols with stable number concentrations and size distributions for long durations, requiring only small quantities of test material (min. 200 mg).

Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring ...

Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few can observe immobilized particles. Moreover, a limited number of studies have experimentally measured the exertable forces on the particles. The designs can be classified as the protruding nanodisk type or the suppressed nanohole type. For the latter, microscopic observation is extremely challenging. In this paper, a new plasmonic tweezer system is introduced to monitor particles, both in directions parallel and orthogonal to the symmetric axis of a plasmonic nanohole structure. This feature enables us to observe the movement of each particle near the rim of the nanohole. Furthermore, we can quantitatively estimate the maximal trapping forces using a new fluidic channel.

A microchip fabrication process that incorporates plasmonic tweezers is presented here. The microchip enables the imaging of a trapped particle to measure maximal trapping forces.

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few ...

Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering thermal wave fields that are disturbed by the defect. This effect is measured and used to locate the defect. We form the destructively interfering wave fields by using a modified projector. The original light engine of the projector is replaced with a fiber-coupled high-power diode laser. Its beam is shaped and aligned to the projector&#39;s spatial light modulator and optimized for optimal optical throughput and homogeneous projection by first characterizing the beam profile, and, second, correcting it mechanically and numerically. A high-performance infrared (IR) camera is set up according to the tight geometrical situation (including corrections of the geometrical image distortions) and the requirement to detect weak temperature oscillations at the sample surface. Data acquisition can be performed once a synchronization between the individual thermal wave field sources, the scanning stage, and the IR camera is established by using a dedicated experimental setup which needs to be tuned to the specific material being investigated. During data post-processing, the relevant information on the presence of a defect below the surface of the sample is extracted. It is retrieved from the oscillating part of the acquired thermal radiation coming from the so-called depletion line of the sample surface. The exact location of the defect is deduced from the analysis of the spatial-temporal shape of these oscillations in a final step. The method is reference-free and very sensitive to changes within the thermal wave field. So far, the method has been tested with steel samples but is applicable to different materials as well, in particular to temperature sensitive materials.

This method aims at locating vertical subsurface defects. Here, we couple a laser with a spatial light modulator and trigger its video input to heat a sample surface deterministically with two anti-phased modulated lines while acquiring highly resolved thermal images. The defect position is retrieved from evaluating thermal wave interference minima.

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering ...

Experimental Implementation of a New Composite Fabrication Method: Exposing Bare Fibers on the Composite Surface by the Soft Layer Method

The bipolar plate is a key component in proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs). It is a multi-functional component that should have high electrical conductivity, high mechanical properties, and high productivity.
In this regard, a carbon fiber/epoxy resin composite can be an ideal material to replace the conventional graphite bipolar plate, which often leads to the catastrophic failure of the entire system because of its inherent brittleness. Though the carbon/epoxy composite has high mechanical properties and is easy to manufacture, the electrical conductivity in the through-thickness direction is poor because of the resin-rich layer that forms on its surface. Therefore, an expanded graphite coating was adopted to solve the electrical conductivity issue. However, the expanded graphite coating not only increases the manufacturing costs but also has poor mechanical properties.
In this study, a method to expose fibers on the composite surface is demonstrated. There are currently many methods that can expose fibers by surface treatment after the fabrication of the composite. This new method, however, does not require surface treatment because the fibers are exposed during the manufacture of the composite. By exposing bare carbon fibers on the surface, the electrical conductivity and mechanical strength of the composite are increased drastically.

A protocol to expose bare fibers on the composite surface by eliminating resin rich area is presented. The fibers are exposed during fabrication of the composites, not by the post surface treatment. The exposed carbon composites exhibit high electrical conductivity in the through-thickness direction and high mechanical property.

The bipolar plate is a key component in proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs). It is a multi-functional ...

A 3D-printed Chamber for Organic Optoelectronic Device Degradation Testing

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, using 3D-printing. As these types of devices are sensitive to moisture and oxygen, such a chamber can aid researchers in characterizing the electronic and stability properties. The chamber is intended to be used as a temporary, reusable, and stable environment with controlled properties (including humidity, gas introduction, and temperature). It can be used to protect air-sensitive materials or to expose them to contaminants in a controlled way for degradation studies. To characterize the properties of the chamber, we outline a simple procedure to determine the water vapor transmission rate (WVTR) using relative humidity as measured by a standard humidity sensor. This standard operating procedure, using a 50% infill density of polylactic acid (PLA), results in a chamber that can be used for weeks without any significant loss of device properties. The versatility and ease of use of the chamber allows it to be adapted to any characterization condition that requires a compact-controlled atmosphere.

Here, we present a protocol for the design, manufacture, and use of a simple, versatile 3D-printed and controlled atmospheric chamber for the optical and electrical characterization of air-sensitive organic optoelectronic devices.

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, ...

Cutting Procedures, Tensile Testing, and Ageing of Flexible Unidirectional Composite Laminates

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, where the yarns in each layer are oriented parallel to each other and held in place using binder resins and thin polymer films. The armor is constructed by stacking the unidirectional layers in different orientations. To date, only very preliminary work has been performed to characterize the ageing of the binder resins used in unidirectional laminates and the effects on their performance. For example, during the development of the conditioning protocol used in the National Institute of Justice Standard-0101.06, UD laminates showed visual signs of delamination and reductions in V50, which is the velocity at which half of the projectiles are expected to perforate the armor, after ageing. A better understanding of the material property changes in UD laminates is necessary to comprehend the long-term performance of armors constructed from these materials. There are no current standards recommended for mechanically interrogating unidirectional (UD) laminate materials. This study explores methods and best practices for accurately testing the mechanical properties of these materials and proposes a new test methodology for these materials. Best practices for ageing these materials are also described.

The goal of the study was to develop protocols to prepare consistent specimens for accurate mechanical testing of high-strength aramid or ultra-high-molar-mass polyethylene-based flexible unidirectional composite laminate materials and to describe protocols for performing artificial ageing on these materials.

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, ...