Validation of a Platform for the Electrostatic Characterization of Textile

Floor covering samples of different thickness, pile height, pile design, materials, construction methods, and applied finishes were selected for electrostatic characterization with a standard plotter platform and a newly designed digital platform. There is an existing standard ISO 6356 in which the voltage generated by a human walking on the carpet is measured with human involvement under controlled conditions. A walking person performs the original test procedure to generate the electrostatic charge and manually calculates results. In contrast, the newly designed system does not require a person to calculate peaks and valleys for the generated electrostatic charges, which offers advantages in terms of accuracy, consistency, and reproducibility, and eliminates human error. The electronic platform is extended with an automated foot for a fully automated test, called “automatic mode”, that has a fixed capacitive and resistive circuit, in replace of human body resistance, and capacitance that varies from person to person and over time. The procedure includes both the old and new platforms, where the new platform is placed in a “human walking” mode to compare the two and validate the new device. Next, all the floor coverings are tested in automatic mode with the automated foot to compare and validate results. We conclude that the new testing device can fully characterize the electrostatic behavior of textile without the involvement of a human, which offers advantages in terms of accuracy, consistency, and reproducibility.

Electrostatic Charges of Abrasive Powders: A Role of Particle Size and Humidity

Electrostatically coated abrasives have drawn vast attention in many industrial applications. Therefore, influence of humidity on the electrical properties of α-SiC and α-Al2O3 abrasive powders with three μm-range particle sizes are here investigated using electrostatic charge and DC resistivity analysis. From the three particle size ranges used, 15–16 μm, 60–63 μm and 153–156 μm, the intermediate one (60–63 μm) is found to be associated with the highest charge values, measured using a double Faraday cup method, as well as the highest resistivity for both materials. However, comparing SiC and Al2O3 powders, the latter ones present about twice larger charges in dry and normal humidity states accompanied by several orders of magnitude larger resistivity. Under humid conditions all the powders reveal diminishing charge and resistivity values.

The Effect of 2-Mercaptobenzimidazole-Polyaniline-CeO2 Ternary Nanocomposite Addition as a Superior Pigment for Improvement of Corrosion Resistance in Epoxy Coatings

The 2-mercaptobenzimidazole-polyaniline-ceria (MBI-PANI-CeO2) ternary nanocomposite synthesized and used as pigment into epoxy (EP) to improve protection properties of coating on mild steel. The MBI-PANI-CeO2 nanocomposite was prepared using layer by layer assembly. Initially, the PANI layer was polymerized on the surface of CeO2 nanoparticles. Then, the MBI inhibitor was adsorbed on PANI with opposite electrostatic charges. The anticorrosive performance of EP coatings was investigated using electrochemical impedance spectroscopy, salt spray test, and scanning electron microscopy by incorporating various amounts (0.5, 1, and 2 wt. %) of the MBI-PANI-CeO2 nanocomposite. The EP coating containing 1 wt. % of nanocomposite showed the highest corrosion resistance and minimum agglomeration. This coating indicated the coating resistance of 19.1 MΩ cm2, which is greater than EP and EP/CeO2 coatings. The EP/MBI-PANI-CeO2 (1 wt. %) coating showed water uptake percentage (2.09 %) about two times lower than EP/CeO2 coatings (4.56 wt. %), indicating appropriate barrier performance of inhibitor incorporated EP.

pKAI: a fast and interpretable deep learning approach for accurate electrostatics-driven pKa predictions

The pKa values of ionizable residues influence protein folding, stability and biological function. The pKa in bulk water is known for all residues, however, in a protein environment, it can significantly be affected by confinement and electrostatics. Existing computational methods to estimate pKa shifts rely on theoretical approximations and lengthy computations. Furthermore, the amount of experimentally determined pKa values is still very limited, hindering the development of faster machine learning-based methods. In this work, we use a data set of 6 million pKa shifts — determined by PypKa, a continuum electrostatics method — to train deep learning models that are shown to rival the physics-based predictor. On ~750 experimentally determined data points, our model displays the best accuracy and it is the only one that breaks the 1 pK unit RMSE barrier of this considerably difficult test set. Although trained using a very simplified view of the surroundings of the titratable group (namely, atom types and distances to other titratable groups within a given radius), the models are shown to assign proper electrostatic charges to chemical groups, to keep the known correlation between solvent exposure and pKa shift magnitude, and to grasp the importance of close interactions, including hydrogen bonds. Inference times allow speedups of more than 1000 times faster than physics-based methods, especially for large proteins. By combining speed, accuracy and a reasonable understanding of the theoretical basis for pKa shifts, our models provide a game-changing solution for fast estimations of macroscopic pKa from ensembles of microscopic (pKhalf) values as well as for many downstream applications such as molecular docking and constant-pH molecular dynamics simulations.

Electrostatic Charge Retention in PVDF Nanofiber-Nylon Mesh Multilayer Structure for Effective Fine Particulate Matter Filtration for Face Masks

Currently, almost 70% of the world’s population occupies urban areas. Owing to the high population density in these regions, they are exposed to various types of air pollutants. Fine particle air pollutants (<2.5 μm) can easily invade the human respiratory system, causing health issues. For fine particulate matter filtration, the use of a face mask filter is efficient; however, its use is accompanied by a high-pressure drop, making breathing difficult. Electrostatic interactions in the filter of the face mask constitute the dominant filtration mechanism for capturing fine particulate matter; these masks are, however, significantly weakened by the high humidity in exhaled breath. In this study, we demonstrate that a filter with an electrostatically rechargeable structure operates with normal breathing air power. In our novel face mask, a filter membrane is assembled by layer-by-layer stacking of the electrospun PVDF nanofiber mat formed on a nylon mesh. Tribo/piezoelectric characteristics via multilayer structure enhance filtration performance, even under air-powered filter bending taken as a normal breathing condition. The air gap between nanofiber and mesh layers increases air diffusion time and preserves the electrostatic charges within the multi-layered nanofiber filter membrane under humid air penetration, which is advantageous for face mask applications.

Hybrid Nanoparticles as a Novel Tool for Regulating Psychosine-Induced Neuroinflammation and Demyelination In Vitro and Ex vivo

Polymeric nanoparticles are being extensively investigated as an approach for brain delivery of drugs, especially for their controlled release and targeting capacity. Nose-to-brain administration of nanoparticles, bypassing the blood brain barrier, offers a promising strategy to deliver drugs to the central nervous system. Here, we investigated the potential of hybrid nanoparticles as a therapeutic approach for demyelinating diseases, more specifically for Krabbe’s disease. This rare leukodystrophy is characterized by the lack of enzyme galactosylceramidase, leading to the accumulation of toxic psychosine in glial cells causing neuroinflammation, extensive demyelination and death. We present evidence that lecithin/chitosan nanoparticles prevent damage associated with psychosine by sequestering the neurotoxic sphingolipid via physicochemical hydrophobic interactions. We showed how nanoparticles prevented the cytotoxicity caused by psychosine in cultured human astrocytes in vitro, and how the nanoparticle size and PDI augmented while the electrostatic charges of the surface decreased, suggesting a direct interaction between psychosine and the nanoparticles. Moreover, we studied the effects of nanoparticles ex vivo using mouse cerebellar organotypic cultures, observing that nanoparticles prevented the demyelination and axonal damage caused by psychosine, as well as a moderate prevention of the astrocytic death. Taken together, these results suggest that lecithin-chitosan nanoparticles are a potential novel delivery system for drugs for certain demyelinating conditions such as Krabbe’s disease, due to their dual effect: not only are they an efficient platform for drug delivery, but they exert a protective effect themselves in tampering the levels of psychosine accumulation.

Charge moderated preplanetary growth from single grains to giant aggregates

&lt;p&gt;In early phases of planet formation, bouncing and fragmentation barriers still represent major obstacles. Beginning at micrometer, dust can readily grow to sub-millimeter size in collisions due to cohesion before bouncing prevails. Later, streaming instabilities trigger further growth which might finally results into planetesimal formation by gravitational collapse. However, for streaming instabilities sub-millimeter grains might be too small, therefore there is gap of at least 1 order of magnitude in size which needs to be bridged.&lt;/p&gt; &lt;p&gt;Here, we present our ongoing work how to bridge this gap by charge moderated aggregation [1]. When two (dielectric) grains collide they charge. This tribocharging or collisional charging is omnipresent in nature. We designed drop tower experiments in which we generated charges on glass and basalt grains by collisions in a shaker. In microgravity, the particle trajectories and collisions were observed, and charges were measured by applying an electric field.&lt;/p&gt; &lt;p&gt;In early work, we analyzed millimeter-sized glass grain collisions with a copper plate. The coefficient of restitution increased with the charge on a single grain due to mirror charge forces. That means highly charged grains tend to stick more easily to surfaces than uncharged grains. The velocity where sticking is possible was increased by a factor of 100 up to several dm/s [2].&lt;br /&gt;&amp;#160;&lt;br /&gt;More recently, we used half millimeter basalt spheres and observed sticking events at several cm/s among grains themselves [3]. This is also way higher than predicted by adhesion. In a number of cases, we could observe the sequential formation of aggregates of up to ten single grains. During approach the grains are accelerated due to net charge Coulomb forces but likely also due to higher order charges on the surfaces in agreement to earlier measurements of strong permanent dipole moments [4]. Attraction increases collision cross-sections and the growth is sped up. Growth only stopped by the end of microgravity [3].&amp;#160;&lt;/p&gt; &lt;p&gt;To observe the formation of still larger aggregates we developed a new setup, in which a dense cloud of 150 &amp;#181;m diameter basalt grains was continuously agitated slightly under microgravity and in vacuum. Here, the growth of a giant aggregate of centimeter size was observed collecting nearly all material in one cluster [5].&lt;/p&gt; &lt;p&gt;To conclude, in experiments under various conditions, we see strong evidence that electrostatic charges on grains are able to conquer the bouncing barrier. We observed the bottom-up growth tracking individual particles, stable clusters emerging from dense regions and the formation of giant clusters during agitation. These are all bricks in the wall giving evidence that collisional charging might play a crucial role in planet formation.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;References:&lt;/strong&gt;&lt;/p&gt; &lt;p&gt;[1] Steinpilz, T.; Joeris, K.; Jungmann, F.; Wolf, D.; Brendel, L.; Teiser, J.; Shinbrot, T.; Wurm, G. Nature Physics 2020a, 16, 225-229.&lt;/p&gt; &lt;p&gt;[2] Jungmann, F.; Steinpilz, T.; Teiser, J.; Wurm, G. Journal of Physics Communications 2018, 2 095009, 095009.&lt;/p&gt; &lt;p&gt;[3] Jungmann, F.;Wurm, G. Astronomy and Astrophysics 2021, DOI: https://doi.org/10.1051/0004-6361/202039430.&lt;/p&gt; &lt;p&gt;[4] Steinpilz, T.; Jungmann, F.; Joeris, K.; Teiser, J.; Wurm, G. New Journal of Physics 2020b, 22, 093025.&lt;/p&gt; &lt;p&gt;[5] Teiser, J.; Kruss, M.; Jungmann, F.; Wurm, G. The Astrophysical Journal Letters 2021, 908, L22.&lt;/p&gt;

Solvent-Free Mechanochemical Synthesis of High Transition Biphenyltetracarboxydiimide Liquid Crystals

A series of high temperature alkyl and alkoxy biphenyltetracarboxydiimide liquid crystals have been prepared under ball mill method using solvent-free mechanochemical approach. The thermal properties of the prepared compounds were investigated by deferential scanning calorimetry (DSC) measurements and the textures were identified by polarized optical microscope (POM). The compounds showed smectic mesomorphic behaviour. The results showed the increasing nature of transition temperature Cr-SmC with chain length with increments of the SmC mesophase range. However, the mesophase range of the SmA was decreased with the terminal chain length either for the alkyl or alkoxy terminal groups. Moreover, the DFT theoretical calculations have been conducted give a detailed projection of the structure of the prepared compounds. A conformational investigation of the biphenyl part has been studied. A deep illustration of the experimental mesomorphic behaviour has been discussed in terms of the calculated aspect ratio. A projection of the frontier molecular orbitals as well as molecular electrostatic potential has been studied to show the effect of the polarity of the terminal chains on the level and the gab of the FMOs and the distribution of electrostatic charges on the prepared molecules.

Bioelectronic Measurement of Target Engagement to a Membrane-Bound Transporter

The ability to detect and characterize drug binding to a target protein is of high priority in drug discovery research. However, there are inherent challenges when the target of interest is an integral membrane protein (IMP). Assuming successful purification of the IMP, traditional approaches for measuring binding such as surface plasmon resonance (SPR) and fluorescence resonance energy transfer (FRET) have been proven valuable. However, the mass dependence of SPR signals may preclude the detection of binding events when the ligand has a significantly smaller mass than the target protein. In FRET-based experiments, protein labeling through modification may inadvertently alter protein dynamics. Graphene Bio-Electronic Sensing Technology (GBEST) aims to overcome these challenges. Label-free characterization takes place in a microfluidic chamber wherein a fluid lipid membrane is reconstituted directly above the GBEST sensor surface. By leveraging the high conductivity, sensitivity, and electrical properties of monolayer graphene, minute changes in electrostatic charges arising from the binding and unbinding of a ligand to a native IMP target can be detected in real time and in a mass-independent manner. Using crude membrane fractions prepared from cells overexpressing monocarboxylate transporter 1 (MCT1), we demonstrate the ability to (1) form a fluid lipid bilayer enriched with MCT1 directly on top of the GBEST sensor and (2) obtain kinetic binding data for an anti-MCT1 antibody. Further development of this novel technology will enable characterization of target engagement by both low- and high-molecular-weight drug candidates to native IMP targets in a physiologically relevant membrane environment.