This work was carried out as part of the ICT for Health project, which was financially supported by the Italian Ministry of Education, University and Research (MIUR), under the initiative Departments of Excellence (Italian Budget Law no. 232/2016), through an excellence grant awarded to the Department of Information Technology and Electrical Engineering of the University of Naples Federico II, Naples, Italy. The project was indeed made possible by the support of the Res4Net initiative and the TC-06 (Emerging Technologies in Measurements) of the IEEE Instrumentation and Measurement Society. The authors would like to also thank L. Callegaro, A. Cioffi, S. Criscuolo, A. Cultrera, G. De Blasi, E. De Benedetto, L. Duraccio, E. Leone, and M. Ortolano for their precious contributions in developing, testing, and validating the system.

The study was approved by the Ethical Committee of Psychological Research of the Department of Humanities of the University of Naples Federico II. The volunteers signed informed consent before participating in the experiments.
1. Preparing the non-invasive wearable brain - computer interface
<ol>
	<li>Obtain a low-cost consumer-grade electroencephalograph with dry electrodes, and configure it for single-channel usage.
	<ol>
		<li>Short-circuit or connect any unused input channels on the low-cost electroencephalograph to an internal reference voltage as specified by the inherent datasheet. In doing so, the unused channels are disabled, and they do not generate crosstalk noise.</li>
		<li>Adjust the electroencephalograph gain (typically through a component with variable resistance) to have an input range in the order of 100 &#181;V. 
		NOTE: The EEG signals to be measured are in order of tens of microvolts. However, the dry electrodes are greatly affected by motion artifacts, which result in oscillations in the order of 100 &#181;V due to the variability in the electrode-skin impedance. Increasing the input voltage range helps to limit EEG amplifier saturation, but it does not completely eliminate it. On the other hand, it would be inconvenient to increase the input voltage range even more, because this would affect the voltage resolution in measuring the desired EEG components. Ultimately, the two aspects must be balanced by also taking into account the bit-resolution of the analog-to-digital converter inside the electroencephalograph board.</li>
		<li>Prepare three dry electrodes to connect to the electroencephalograph board. Use a passive electrode (no pre-amplification) as the reference electrode. The remaining two measuring electrodes should be active ones (i.e., involve pre-amplification and eventual analog filtering). 
		NOTE: Electrodes placed on a hairy scalp area require pins to overcome electrode-skin contact impedance. If possible, solder silver pins with flat heads (to avoid too much pain for the user), or ideally use conducting (soft) rubber with an Ag/AgCl coating.</li>
	</ol>
	</li>
	<li>Obtain commercial smart glasses with an Android operating system and a refresh rate of 60 Hz. Alternatively, use a lower refresh rate. A higher refresh rate would be desirable for stimuli as there would be less eye fatigue, but there are no currently available solutions on the market.
	<ol>
		<li>Download the source code of an Android application for communication or control, or develop one.</li>
		<li>Replace the virtual buttons in the application with flickering icons by changing the inherent object (usually in Java or Kotlin). White squares with at least 5% screen dimension are recommended. Usually, the bigger the stimulating square, the higher the SSVEP component to detect will be, but an optimum can be found depending on the specific case. Recommended frequencies are 10 Hz and 12 Hz flickering. Implement the flicker on the graphical processing unit (GPU) to avoid overloading the computing unit (CPU) of the smart glasses. For this purpose, use objects from the OpenGL library.</li>
		<li>Implement a module of the Android application for real-time processing of the input EEG stream. The Android USB Service can be added so that the stream may be received via USB. The real-time processing may simply apply a sliding window to the EEG stream by considering the incoming packets. Calculate the power spectral densities associated with the 10 Hz and 12 Hz frequencies through a fast Fourier transform function. A trained classifier can, thus, distinguish that the user is looking at the 10 Hz flickering icon or the 12 Hz flickering icon by classifying the power spectral density features.</li>
	</ol>
	</li>
</ol>
2. Calibrating the SSVEP-based brain - computer interface
NOTE: Healthy volunteers were chosen for this study. Exclude subjects with a history of brain diseases. The involved subjects were required to have normal or corrected-to-normal vision. They were instructed to be relaxed during the experiments and to avoid unnecessary movements, especially of the head.
<ol>
	<li>Let the user wear the smart glasses with the Android application.</li>
	<li>Let the user wear a tight headband for holding the electrodes.</li>
	<li>Connect the low-cost electroencephalograph to a PC via a USB cable while the PC is disconnected from the main power supply.
	<ol>
		<li>Initially disconnect all the electrodes from the electroencephalograph acquisition board to start from a known condition.</li>
		<li>In this phase, the EEG stream is processed offline on the PC with a script compatible with the processing implemented in the Android application. Start the script to receive the EEG signals and visualize them.</li>
	</ol>
	</li>
	<li>Check the displayed signal that is processed offline. This must correspond to only the quantization noise of the EEG amplifier.</li>
	<li>Connect the electrodes.
	<ol>
		<li>Apply the passive electrode to the left ear with a custom clip, or use an ear-clip electrode. The output signal must remain unchanged at this step because the measuring differential channel is still an open circuit.</li>
		<li>Connect an active electrode to the negative terminal of the differential input of the measuring EEG channel, and apply to the frontal region (Fpz standard location) with a headband. After a few seconds, the signal should return to zero (quantization noise).</li>
		<li>Connect the other active electrode to the positive terminal of the differential input of the measuring EEG channel, and apply to the occipital region (Oz standard location) with the headband. A brain signal is now displayed, which corresponds to the visual activity measured with respect to the frontal brain area (no visual activity foreseen there).</li>
	</ol>
	</li>
	<li>Acquire signals for system calibration.
	<ol>
		<li>Repeatedly stimulate the user with 10 Hz and 12 Hz (and eventually other) flickering icons by starting the flickering icon in the Android application, and acquire and save the inherent EEG signals for offline processing. Ensure each stimulation in this phase consists of a single icon flickering for 10 s, and start the flickering icon by pressing on the touchpad of the smart glasses while also starting the EEG acquisition and visualization script.</li>
		<li>From the 10 s signals associated with each stimulation, extract two features by using the fast Fourier transform: the power spectral density at 10 Hz and at 12 Hz. Alternatively, consider second harmonics (20 Hz and 24 Hz).</li>
		<li>Use a representation of the acquired signals in the features domain to train a support vector machine classifier. Use a tool (in Matlab or Python) to identify the parameters of a hyperplane with an eventual kernel based on the input features. The trained model will be capable of classifying future observations of EEG signals.</li>
	</ol>
	</li>
</ol>
3. Assemble the final wearable and portable SSVEP-based interface
<ol>
	<li>Disconnect the USB cable from the PC, and connect it directly to the smart glasses.</li>
	<li>Insert the parameters of the trained classifier into the Android application. The system is now ready.</li>
</ol>

<ol>
	<li>Wolpaw, J. R., 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=Brain-computer+interface+technology:+A+review+of+the+first+international+meeting.">Brain-computer interface technology: A review of the first international meeting.</a> IEEE Transactions on Rehabilitation Engineering. 8 (2), 164-173 (2000).</li><li>Zander, T. O., Kothe, C., Jatzev, S., Gaertner, M., Tan, D. S., Nijholt, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancing+human-computer+interaction+with+input+from+active+and+passive+brain-computer+interfaces.">Enhancing human-computer interaction with input from active and passive brain-computer interfaces.</a> Brain-Computer Interfaces. , 181-199 (2010).</li><li>Ron-Angevin, R., 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=Brain-computer+interface+application:+Auditory+serial+interface+to+control+a+two-class+motor-imagery-based+wheelchair.">Brain-computer interface application: Auditory serial interface to control a two-class motor-imagery-based wheelchair.</a> Journal of Neuroengineering and Rehabilitation. 14 (1), 49 (2017).</li><li>Ahn, M., Lee, M., Choi, J., Jun, S. 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A., Liu, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EEG-based+brain-controlled+mobile+robots:+A+survey.">EEG-based brain-controlled mobile robots: A survey.</a> IEEE Transactions on Human-Machine Systems. 43 (2), 161-176 (2013).</li><li>Arpaia, P., Callegaro, L., Cultrera, A., Esposito, A., Ortolano, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metrological+characterization+of+a+low-cost+electroencephalograph+for+wearable+neural+interfaces+in+industry+4.0+applications.">Metrological characterization of a low-cost electroencephalograph for wearable neural interfaces in industry 4.0 applications.</a> IEEE International Workshop on Metrology for Industry 4.0 &amp; IoT (MetroInd4. 0&amp;IoT). , 1-5 (2021).</li><li>R&#252;&#223;mann, M., 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=Industry+4.0:+The+future+of+productivity+and+growth+in+manufacturing+industries.">Industry 4.0: The future of productivity and growth in manufacturing industries.</a> Boston Consulting Group. 9 (1), 54-89 (2015).</li><li>Angrisani, L., Arpaia, P., Moccaldi, N., Esposito, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wearable+augmented+reality+and+brain+computer+interface+to+improve+human-robot+interactions+in+smart+industry:+A+feasibility+study+for+SSVEP+signals.">Wearable augmented reality and brain computer interface to improve human-robot interactions in smart industry: A feasibility study for SSVEP signals.</a> IEEE 4th International Forum on Research and Technology for Society and Industry (RTSI). , 1-5 (2018).</li><li>Brunner, C., et al. <a target="_blank" 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control system of robotic arm based on augmented reality-assisted brain-computer interface.</a> Journal of Neural Engineering. 18 (6), 066005 (2021).</li><li>Ball, T., Kern, M., Mutschler, I., Aertsen, A., Schulze-Bonhage, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Signal+quality+of+simultaneously+recorded+invasive+and+non-invasive+EEG.">Signal quality of simultaneously recorded invasive and non-invasive EEG.</a> Neuroimage. 46 (3), 708-716 (2009).</li><li>Grosse-Wentrup, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=What+are+the+causes+of+performance+variation+in+brain-computer+interfacing.">What are the causes of performance variation in brain-computer interfacing.</a> International Journal of Bioelectromagnetism. 13 (3), 115-116 (2011).</li><li>Arpaia, P., Esposito, A., Natalizio, A., Parvis, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+to+successfully+classify+EEG+in+motor+imagery+BCI:+A+metrological+analysis+of+the+state+of+the+art.">How to successfully classify EEG in motor imagery BCI: A metrological analysis of the state of the art.</a> Journal of Neural Engineering. 19 (3), (2022).</li><li>Ajami, S., Mahnam, A., Abootalebi, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+practical+high+frequency+brain-computer+interface+based+on+steady-state+visual+evoked+potentials+using+a+single+channel+of+EEG.">Development of a practical high frequency brain-computer interface based on steady-state visual evoked potentials using a single channel of EEG.</a> Biocybernetics and Biomedical Engineering. 38 (1), 106-114 (2018).</li><li>Friedman, D., Nakatsu, R., Rauterberg, M., Ciancarini, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brain-computer+interfacing+and+virtual+reality.">Brain-computer interfacing and virtual reality.</a> Handbook of Digital Games and Entertainment Technologies. , 151-171 (2015).</li><li>Wang, M., Li, R., Zhang, R., Li, G., Zhang, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+wearable+SSVEP-based+BCI+system+for+quadcopter+control+using+head-mounted+device.">A wearable SSVEP-based BCI system for quadcopter control using head-mounted device.</a> IEEE Access. 6, 26789-26798 (2018).</li><li>Arpaia, P., Callegaro, L., Cultrera, A., Esposito, A., Ortolano, M. <a target="_blank" 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R., Birbaumer, N., McFarland, D. J., Pfurtscheller, G., Vaughan, 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=Brain-computer+interfaces+for+communication+and+control.">Brain-computer interfaces for communication and control.</a> Clinical Neurophysiology. 113 (6), 767-791 (2002).</li><li>Duszyk, A., 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=Towards+an+optimization+of+stimulus+parameters+for+brain-computer+interfaces+based+on+steady+state+visual+evoked+potentials.">Towards an optimization of stimulus parameters for brain-computer interfaces based on steady state visual evoked potentials.</a> PLoS One. 9 (11), 112099 (2014).</li><li>Prasad, P. S., 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=SSVEP+signal+detection+for+BCI+application.">SSVEP signal detection for BCI application.</a> IEEE 7th International Advance Computing Conference (IACC). , 590-595 (2017).</li><li>Xing, X., 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=A+high-speed+SSVEP-based+BCI+using+dry+EEG+electrodes).">A high-speed SSVEP-based BCI using dry EEG electrodes).</a> Scientific Reports. 8, 14708 (2018).</li><li>Luo, A., Sullivan, T. 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The authors have nothing to disclose.

The proper functioning of the system involves two crucial aspects: SSVEP elicitation and signal acquisition. Aside from the specific devices chosen for the current study, SSVEP could be elicited with different devices providing a flickering light, though smart glasses are preferred to ensure wearability and portability. Analogously, further commercial electroencephalographs could be considered, but they would have to be wearable, portable, and involve a minimum number of dry electrodes to be user-friendly. Moreover, the ...

A brain-computer interface (BCI) is a system allowing communication with and/or control of devices without natural neural pathways1. BCI technology is the closest thing that humanity has to controlling objects with the power of the mind. From a technical point of view, the system operation works by measuring induced or evoked brain activity, which could either be involuntarily or voluntarily generated from the subject2. Historically, research focused on aiding people with motor disabilities through BCI3, but a growing number of companies today offer BCI-based instrumentation for gaming4, robotics5, industry6, and other applications involving human-machine interaction. Notably, BCIs may play a role in the fourth industrial revolution, namely industry 4.07, where cyber-physical production systems are changing the interaction between humans and the surrounding environment8. Broadly speaking, the European project BNCI Horizon 2020 identified application scenarios such as replacing, restoring, improving, enhancing, or supplementing lost natural functions of the central nervous system, as well as the usage of BCI in investigating the brain9.
In this framework, recent technological advances mean brain-computer interfaces may be applicable for usage in daily life10,11. To achieve this aim, the first requirement is non-invasiveness, which is important for avoiding the risks of surgical intervention and increasing user acceptance. However, it is worth noting that the choice of non-invasive neuroimaging affects the quality of measured brain signals, and the BCI design must then deal with the associated pitfalls12. In addition, wearability and portability are required. These requirements are in line with the need for a user-friendly system but also pose some constraints. Overall, the mentioned hardware constraints are addressed by the usage of an electroencephalographic (EEG) system with gel-free electrodes6. Such an EEG-based BCI would also be low-cost. Meanwhile, in terms of the software, minimal user training (or ideally no training) would be desired; namely, it would be best to avoid lengthy periods for tuning the processing algorithm before the user can use the system. This aspect is critical in BCIs because of inter-subject and intra-subject non-stationarity13,14.
Previous literature has demonstrated that the detection of evoked brain potentials is robust with respect to non-stationarity and noise in signal acquisition. In other words, BCIs relying on the detection of evoked potential are termed reactive, and are the best-performing BCIs in terms of brain pattern recognition15. Nevertheless, they require sensory stimulation, which is probably the main drawback of such interfaces. The goal of the proposed method is, thus, to build a highly wearable and portable BCI relying on wearable, off-the-shelf instrumentation. The sensory stimuli here consist of flickering lights, generated by smart glasses, that are capable of eliciting steady-state visually evoked potentials (SSVEPs). Previous works have already considered integrating BCI with virtual reality either alone or in conjunction with augmented reality16. For instance, a BCI-AR system was proposed to control a quadcopter with SSVEP17. Virtual reality, augmented reality, and other paradigms are referred to with the term extended reality. In such a scenario, the choice of smart glasses complies with the wearability and portability requirements, and smart glasses can be integrated with a minimal EEG acquisition setup. This paper shows that SSVEP-based BCI also requires minimal training while achieving acceptable classification performance for low-medium speed communication and control applications. Hence, the technique is applied to BCI for daily-life applications, and it appears especially suitable for industry and healthcare.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Conductive rubber with Ag/AgCl coating&#160;</td>
			<td>ab medica s.p.a.</td>
			<td>N/A</td>
			<td>Alternative electrodes &#8211; type 2</td>
		</tr>
		<tr>
			<td>Earclip electrode</td>
			<td>OpenBCI</td>
			<td>N/A</td>
			<td>Ear clip</td>
		</tr>
		<tr>
			<td>EEG-AE</td>
			<td>Olimex</td>
			<td>N/A</td>
			<td>Active electrodes</td>
		</tr>
		<tr>
			<td>EEG-PE</td>
			<td>Olimex</td>
			<td>N/A</td>
			<td>Passive electrode</td>
		</tr>
		<tr>
			<td>EEG-SMT</td>
			<td>Olimex</td>
			<td>N/A</td>
			<td>Low-cost electroencephalograph</td>
		</tr>
		<tr>
			<td>Moverio BT-200</td>
			<td>Epson</td>
			<td>N/A</td>
			<td>Smart glasses</td>
		</tr>
		<tr>
			<td>Snap electrodes</td>
			<td>OpenBCI</td>
			<td>N/A</td>
			<td>Alternative electrodes &#8211; type 1</td>
		</tr>
	</tbody>
</table>

a single-channel and non-invasive wearable brain-computer interface for industry and healthcare

The present work focuses on how to build a wearable brain-computer interface (BCI). BCIs are a novel means of human-computer interaction that relies on direct measurements of brain signals to assist both people with disabilities and those who are able-bodied. Application examples include robotic control, industrial inspection, and neurorehabilitation. Notably, recent studies have shown that steady-state visually evoked potentials (SSVEPs) are particularly suited for communication and control applications, and efforts are currently being made to bring BCI technology into daily life. To achieve this aim, the final system must rely on wearable, portable, and low-cost instrumentation. In exploiting SSVEPs, a flickering visual stimulus with fixed frequencies is required. Thus, in considering daily-life constraints, the possibility to provide visual stimuli by means of smart glasses was explored in this study. Moreover, to detect the elicited potentials, a commercial device for electroencephalography (EEG) was considered. This consists of a single differential channel with dry electrodes (no conductive gel), thus achieving the utmost wearability and portability. In such a BCI, the user can interact with the smart glasses by merely staring at icons appearing on the display. Upon this simple principle, a user-friendly, low-cost BCI was built by integrating extended reality (XR) glasses with a commercially available EEG device. The functionality of this wearable XR-BCI was examined with an experimental campaign involving 20 subjects. The classification accuracy was between 80%-95% on average depending on the stimulation time. Given these results, the system can be used as a human-machine interface for industrial inspection but also for rehabilitation in ADHD and autism.

A possible implementation of the system described above is shown in Figure 1;&#160;this implementation allows the user to navigate in augmented reality through brain activity. The flickering icons on the smart glasses display correspond to actions for the application (Figure 1A), and, thus, these glasses represent a substitute for a traditional interface based on button presses or a touchpad. The efficacy of such an interaction i...

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A Single-Channel and Non-Invasive Wearable Brain-Computer Interface for Industry and Healthcare

This paper discusses how to build a brain-computer interface by relying on consumer-grade equipment and steady-state visually evoked potentials. For this, a single-channel electroencephalograph exploiting dry electrodes was integrated with augmented reality glasses for stimuli presentation and output data visualization. The final system was non-invasive, wearable, and portable.

The present work focuses on how to build a wearable brain-computer interface (BCI). BCIs are a novel means of human-computer interaction that relies on ...

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2.1K Views.  University of Naples Federico II. This paper discusses how to build a brain-computer interface by relying on consumer-grade equipment and steady-state visually evoked potentials. For this, a single-channel electroencephalograph exploiting dry electrodes was integrated with augmented reality glasses for stimuli presentation and output data visualization. The final system was non-invasive, wearable, and portable. 

Video: A Single-Channel and Non-Invasive Wearable Brain-Computer Interface for Industry and Healthcare

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a 15N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the 1H isotope in depths up to about 2 &#956;m from the target surface. Surface H coverages are measured with a sensitivity in the order of ~1013 cm-2 (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~1018 cm-3 (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal 15N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, 1H(15N,&#945;&#947;)12C NRA is ideally suited for hydrogen analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of 15N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).

We illustrate the application of 1H(15N,&#945;&#947;)12C resonant nuclear reaction analysis (NRA) to quantitatively evaluate the density of hydrogen atoms on the surface, in the volume, and at an interfacial layer of solid materials. The near-surface hydrogen depth profiling of a Pd(110) single crystal and of SiO2/Si(100) stacks is described.

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and ...

Hand Controlled Manipulation of Single Molecules via a Scanning Probe Microscope with a 3D Virtual Reality Interface

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building blocks in a bottom-up approach is still open. The scanning probe microscope (SPM) could be a tool of choice; however, SPM-based manipulation was until recently limited to two dimensions (2D). Binding the SPM tip to a molecule at a well-defined position opens an opportunity of controlled manipulation in 3D space. Unfortunately, 3D manipulation is largely incompatible with the typical 2D-paradigm of viewing and generating SPM data on a computer. For intuitive and efficient manipulation we therefore couple a low-temperature non-contact atomic force/scanning tunneling microscope (LT NC-AFM/STM) to a motion capture system and fully immersive virtual reality goggles. This setup permits &#34;hand controlled manipulation&#34; (HCM), in which the SPM tip is moved according to the motion of the experimenter&#39;s hand, while the tip trajectories as well as the response of the SPM junction are visualized in 3D. HCM paves the way to the development of complex manipulation protocols, potentially leading to a better fundamental understanding of nanoscale interactions acting between molecules on surfaces. Here we describe the setup and the steps needed to achieve successful hand-controlled molecular manipulation within the virtual reality environment.

We demonstrate the precise manipulation of individual organic molecules on a metal surface with the tip of a scanning probe microscope driven in 3D by the experimenter's hand using a motion capture system and fully immersive virtual reality goggles.

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building ...

Gain-compensation Methodology for a Sinusoidal Scan of a Galvanometer Mirror in Proportional-Integral-Differential Control Using Pre-emphasis Techniques

Galvanometer mirrors are used for optical applications such as target tracking, drawing, and scanning control because of their high speed and accuracy. However, the responsiveness of a galvanometer mirror is limited by its inertia; hence, the gain of a galvanometer mirror is reduced when the control path is steep. In this research, we propose a method to extend the corresponding frequency using a pre-emphasis technique to compensate for the gain reduction of galvanometer mirrors in sine-wave path tracking using proportional-integral-differential (PID) control. The pre-emphasis technique obtains an input value for a desired output value in advance. Applying this method to control the galvanometer mirror, the raw gain of a galvanometer mirror in each frequency and amplitude for sine-wave path tracking using a PID controller was calculated. Where PID control is not effective, maintaining a gain of 0 dB to improve the trajectory tracking accuracy, it is possible to expand the speed range in which a gain of 0 dB can be obtained without tuning the PID control parameters. However, if there is only one frequency, amplification is possible with a single pre-emphasis coefficient. Therefore, a sine wave is suitable for this technique, unlike triangular and sawtooth waves. Hence, we can adopt a pre-emphasis technique to configure the parameters in advance, and we need not prepare additional active control models and hardware. The parameters are updated immediately within the next cycle because of the open loop after the pre-emphasis coefficients are set. In other words, to regard the controller as a black box, we need to know only the input-to-output ratio, and detailed modeling is not required. This simplicity allows our system to be easily embedded in applications. Our method using the pre-emphasis technique for a motion-blur compensation system and the experiment conducted to evaluate the method are explained.

We propose a method to extend the corresponding frequency by using a pre-emphasis technique. This method compensates for the gain reduction of a galvanometer mirror in sine-wave path tracking using proportional-integral-differential control.

Galvanometer mirrors are used for optical applications such as target tracking, drawing, and scanning control because of their high speed and accuracy. ...

O-cresol Concentration Online Measurement Based On Near Infrared Spectroscopy Via Partial Least Square Regression

Unlike macroscopic process variables, near-infrared spectroscopy provides process information at the molecular level and can significantly improve the prediction of the components in industrial processes. The ability to record spectra for solid and liquid samples without any pretreatment is advantageous and the method is widely used. However, the disadvantages of analyzing high-dimensional near-infrared spectral data include information redundancy and multicollinearity of the spectral data. Thus, we propose to use partial least squares regression method, which has traditionally been used to reduce the data dimensionality and eliminate the collinearity between the original features. We implement the method for predicting the o-cresol concentration during the production of polyphenylene ether. The proposed approach offers the following advantages over component regression prediction methods: 1) partial least squares regression solves the multicollinearity problem of the independent variables and effectively avoids overfitting, which occurs in a regression analysis due to the high correlation between the independent variables; 2) the use of the near-infrared spectra results in high accuracy because it is a non-destructive and non-polluting method to obtain information at microscopic and molecular scales.

The protocol describes a method of predicting o-cresol concentration during the production of polyphenylene ether using near-infrared spectroscopy and partial least squares regression. To describe the process more clearly and completely, an example of predicting the o-cresol concentration during the production of polyphenylene is used to clarify the steps.

Unlike macroscopic process variables, near-infrared spectroscopy provides process information at the molecular level and can significantly improve the ...

Evaluating Usability Aspects of a Mixed Reality Solution for Immersive Analytics in Industry 4.0 Scenarios

In medicine or industry, the analysis of high-dimensional data sets is increasingly required. However, available technical solutions are often complex to use. Therefore, new approaches like immersive analytics are welcome. Immersive analytics promise to experience high-dimensional data sets in a convenient manner for various user groups and data sets. Technically, virtual-reality devices are used to enable immersive analytics. In Industry 4.0, for example, scenarios like the identification of outliers or anomalies in high-dimensional data sets are pursued goals of immersive analytics. In this context, two important questions should be addressed for any developed technical solution on immersive analytics: First, is the technical solutions being helpful or not? Second, is the bodily experience of the technical solution positive or negative? The first question aims at the general feasibility of a technical solution, while the second one aims at the wearing comfort. Extant studies and protocols, which systematically address these questions are still rare. In this work, a study protocol is presented, which mainly investigates the usability for immersive analytics in Industry 4.0 scenarios. Specifically, the protocol is based on four pillars. First, it categorizes users based on previous experiences. Second, tasks are presented, which can be used to evaluate the feasibility of the technical solution. Third, measures are presented, which quantify the learning effect of a user. Fourth, a questionnaire&#160;evaluates the stress level when performing tasks. Based on these pillars, a technical setting was implemented that uses mixed reality smartglasses to apply the study protocol. The results of the conducted study show the applicability of the protocol on the one hand and the feasibility of immersive analytics in Industry 4.0 scenarios on the other. The presented protocol includes a discussion of discovered limitations.

This protocol delineates the technical setting of a developed mixed reality application that is used for immersive analytics. Based on this, measures are presented, which were used in a study to gain insights into usability aspects of the developed technical solution.

In medicine or industry, the analysis of high-dimensional data sets is increasingly required. However, available technical solutions are often complex to ...

A Multi-Cue Bioreactor to Evaluate the Inflammatory and Regenerative Capacity of Biomaterials under Flow and Stretch

The use of resorbable biomaterials to induce regeneration directly in the body is an attractive strategy from a translational perspective. Such materials induce an inflammatory response upon implantation, which is the driver of subsequent resorption of the material and the regeneration of new tissue. This strategy, also known as in situ tissue engineering, is pursued to obtain cardiovascular replacements such as tissue-engineered vascular grafts. Both the inflammatory and the regenerative processes are determined by the local biomechanical cues on the scaffold (i.e., stretch and shear stress). Here, we describe in detail the use of a custom-developed bioreactor that uniquely enables the decoupling of stretch and shear stress on a tubular scaffold. This allows for the systematic and standardized evaluation of the inflammatory and regenerative capacity of tubular scaffolds under the influence of well-controlled mechanical loads, which we demonstrate on the basis of a dynamic co-culture experiment using human macrophages and myofibroblasts. The key practical steps in this approach&#8212;the construction and setting up of the bioreactor, preparation of the scaffolds and cell seeding, application and maintenance of stretch and shear flow, and sample harvesting for analysis&#8212;are discussed in detail.

The goal of this protocol is to execute a dynamic co-culture of human macrophages and myofibroblasts in tubular electrospun scaffolds to investigate material-driven tissue regeneration, using a bioreactor which enables the decoupling of shear stress and cyclic stretch.

The use of resorbable biomaterials to induce regeneration directly in the body is an attractive strategy from a translational perspective. Such materials ...

Elaborate Control of Inkjet Printer for Fabrication of Chip-based Supercapacitors

There are tremendous efforts in various fields to apply the inkjet printing method for the fabrication of wearable devices, displays, and energy storage devices. To get high-quality products, however, sophisticated operation skills are required depending on the physical properties of the ink materials. In this regard, optimizing the inkjet printing parameters is as important as developing the physical properties of the ink materials. In this study, optimization of the inkjet printing software parameters is presented for fabricating a supercapacitor. Supercapacitors are attractive energy storage systems because of their high power density, long lifespan, and various applications as power sources. Supercapacitors can be used in the Internet of Things (IoT), smartphones, wearable devices, electrical vehicles (EVs), large energy storage systems, etc. The wide range of applications demands a new method that can fabricate devices in various scales. The inkjet printing method can break through the conventional fixed-size&#160;fabrication method.

This paper provides a technique for manufacturing chip-based supercapacitors using an inkjet printer. Methodologies are described in detail to synthesize inks, adjust software parameters, and analyze the electrochemical results of the manufactured supercapacitor.

There are tremendous efforts in various fields to apply the inkjet printing method for the fabrication of wearable devices, displays, and energy storage ...

Evaluating the Electrochemical Properties of Supercapacitors using the Three-Electrode System

The three-electrode system is a basic and general analytical platform for investigating the electrochemical performance and characteristics of energy storage systems at the material level. Supercapacitors are one of the most important emergent energy storage systems developed in the past decade. Here, the electrochemical performance of a supercapacitor was evaluated using a three-electrode system with a potentiostat device. The three-electrode system consisted of a working electrode (WE), reference electrode (RE), and counter electrode (CE). The WE is the electrode where the potential is controlled and the current is measured, and it is the target of research. The RE acts as a reference for measuring and controlling the potential of the system, and the CE is used to complete the closed circuit to enable electrochemical measurements. This system provides accurate analytical results for evaluating electrochemical parameters such as the specific capacitance, stability, and impedance through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Several experimental design protocols are proposed by controlling the parameter values of the sequence when using a three-electrode system with a potentiostat device to evaluate the electrochemical performance of supercapacitors. Through these protocols, the researcher can set up a three-electrode system to obtain reasonable electrochemical results for assessing the performance of supercapacitors.

The protocol describes the evaluation of various electrochemical properties of supercapacitors using a three-electrode system with a potentiostat device.

The three-electrode system is a basic and general analytical platform for investigating the electrochemical performance and characteristics of energy ...