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[en] Highlights: • Triboelectric nanogenerator was prepared using force-assembled colloidal arrays. • The electrical performance was determined by the structures and colloidal size. • They displayed high electric output, stability, and humidity resistance. We introduce a novel, robust, cost-effective, and scalable approach for the preparation of a large-area force-assembled triboelectric nanogenerator (FTENG), which allows a stable and high electric output under a wide range of humidity conditions through its dual-sized morphology (i.e., microstructures and nanostructures). In this study, hexagonally packed colloidal arrays prepared by a force assembly approach rather than by conventional self-assembly were used as a mold for a triboelectric poly(dimethylsiloxane) (PDMS) replica with desired pattern shapes (intaglio and embossed structures) and sizes. The morphological size of the PDMS films was determined by the diameter of the force-assembled colloids. The electrical output performance of FTENGs composed of electrodes and a PDMS film increased substantially as the size of the micropores (for intaglio-structured PDMS) or embossed features (for embossed-structured PDMS) decreased. Furthermore, the triboelectric PDMS film with micro-/nanosized features (i.e., dual-embossed PDMS) displayed a remarkable electrical output of 207 V (open-circuit voltage under a compressive force of 90 N in relative humidity (RH) of 20%) and high hydrophobicity compared to that of PDMS films with flat, intaglio or embossed structures. This device maintained a high electric output even in a high-humidity environment (i.e., open-circuit output voltage ~175 V in RH 80%). Our approach using force-assembly and hierarchical surface morphology will provide a novel and effective framework for developing strong power sources in various self-powered electronics.
[en] In spite of extensive investigation and applications, influence of oxygen (O), and humidity on polyaniline (PANI) behaviour is not well understood. For this reason we have performed semi-empirical quantum mechanics, and ab-initio calculations of the pernigraniline base (PNB) PANI oligomers, of various lengths, before and after approach of H2O, O2 , and hydroxyl (OH −) group, and attachment of OH − and O to various molecular positions. Structure, charge and electrostatic potential distribution, relevant energies and enthalpies, infrared and electronic spectra of the PNB tetramer equilibrium conformation, and their changes induced by specific OH − , and O attachments are determined. These results provide identification of the most probable positions for O2 and H2O approach to PNB_PANI, enthalpies of OH − and O attachments to them, changes of molecular properties induced by the attachments, and infrared and electronic modes that are most suitable for the attachments detection. The results are compared to the existing experimental data, and the results of similar calculations, and implications for the PNB_PANI applications are notified. © 2019 Elsevier B.V.
[en] The filtration efficiency for nanoparticles down to 1 nm in size through glass fibrous filters was measured using an improved PSM-CNC system. In addition, the effects of relative humidity and particle charge were investigated for various nanoparticle diameters. The results show that the filtration efficiencies were independent of humidity and affected by particle charge in the case of particles below 100 nm in size. For particles smaller than 2 nm, the particle penetrations increased with decreasing particle size. These results suggest that the thermal rebound phenomena would be operative for nanoparticles with diameters below 2 nm, even though it would depend on the states of both the particles and the filter media. These results are particularly important for experimental investigations of the behavior of nanoparticles on a filter
[en] The objective of this paper is to evaluate the potential error in estimating the net radiation and reference evapotranspiration resulting from errors in the measurement or estimation of weather parameters. A methodology for estimating the net radiation using hourly weather variables measured at a typical agrometeorological station (e.g., solar radiation, temperature and relative humidity) is presented. Then the error propagation analysis is made for net radiation and for reference evapotranspiration. Data from the Raimat weather station, which is located in the Catalonia region of Spain, are used to illustrate the error relationships. The results show that temperature, relative humidity and cloud cover errors have little effect on the net radiation or reference evapotranspiration. A 5°C error in estimating surface temperature leads to errors as big as 30 W m−2 at high temperature. A 4% solar radiation (Rs) error can cause a net radiation error as big as 26 W m−2 when Rs ≈ 1000 W m−2. However, the error is less when cloud cover is calculated as a function of the solar radiation. The absolute error in reference evapotranspiration (ETo) equals the product of the net radiation error and the radiation term weighting factor [W = Δ(Δ1+γ)] in the ETo equation. Therefore, the ETo error varies between 65 and 85% of the Rn error as air temperature increases from about 20° to 40°C. (author)
[en] Highlights: • Impact of environmental relative humidity on NCA based cell performance is investigated. • Higher environmental relative humidity impacts first discharge capacity and coulombic efficiency. • Higher environmental relative humidity has negligible impact on cycling stability of NCA cathode.
[en] Atomic force microscopy (AFM) has been used to measure the adhesion force between a flat Si(0 0 1) wafer and a micrometer sized flat silicon AFM tip. Force–distance curves have been recorded at different setpoints in order to elucidate their individual effect on the derived adhesion force. No dependence of the derived adhesion force on the applied load has been detected, making sure that no plastic changes in the morphology of either tip and/or sample occur. Other setpoints as the residence time of the tip at the substrate, the relative humidity, the size of the tip and the retraction velocity of the tip have been varied systematically. We have found that the adhesion force depends strongly on the velocity of the z-piezo and the tip size while, at least within the 0.5–41 s time window, the residence time does not have any measurable effect on the adhesion force. The time scale of the retraction varies between 0.2 and 25 s. The increase of the adhesion force with increasing retraction speed is ascribed to the viscous force. Finally, the adhesion force increases with increasing relative humidity.
[en] Among three types of proposed magnetic wood, powder-type magnetic wood can be made of recycled magnetic materials from IT devices, consumer electronics and waste wood. Because of its wood powder content, powder-type magnetic wood shows special characteristics different from those of typical magnetic materials. We focused on the relationship between humidity and magnetic characteristics of powder-type magnetic wood. The magnetic powder ratio, wood powder density and magnetic binder density were all examined as parameters for AC permeability
[en] The use of plants for ecological remediation is an important method of controlling heavy metals in polluted land. Cotinus coggygria is a landscape plant that is used extensively in landscaping and afforestation. In this study, the cadmium tolerance level of C. coggygria was evaluated using electrical impedance spectroscopy (EIS) to lay a theoretical foundation for broad applications of this species in Cd-polluted areas and provide theoretical support to broaden the application range of the EIS technique. Two-year-old potted seedlings of C. coggygria were placed in a greenhouse to analyse the changes in the growth, water content and EIS parameters of the roots following treatment with different Cd concentrations (50, 100, 200, 500, 1000 and 1500 mg kg−1), and soil without added Cd was used as the control. The roots grew well following Cd treatments of 50 and 100 mg kg−1. The Cd contents increased with the increase in Cd concentration in the soil. However, the lowest root Cd content was found at 4 months of treatment. The extracellular resistance re and the intracellular resistance ri increased first overall and then decreased with the increasing Cd concentration, and both parameters increased with a longer treatment duration. The water content had a significant negative correlation with the Cd content (P < 0.01) and the re (P < 0.05). C. coggygria could tolerate a soil Cd concentration of 100 mg kg−1. There was a turning point in the growth, water content and EIS parameters of the C. coggygria roots when the soil Cd concentration reached 200 mg kg−1. The root water content and re could reflect the level of Cd tolerance in C. coggygria.
[en] The smaller size and higher integration of electronic components result in smaller gaps between metal conducting layers in an electronic package and printed circuit board (PCB). Under high temperature and humidity, electronic components respond to applied voltages by electrochemical ionization of metal and the formation of a filament, which leads to short-circuit failure of an electronic component, which is termed electrochemical migration (ECM). In this study, a four-layered PCB with SnPb electroplated through-hole-via was used to determine the ECM characteristics of a eutectic SnPb (63Sn-37Pb, weight percent) solder at a temperature of 85 deg. C, a relative humidity of 85%, and DC bias voltages between 75 and 100 V. Additionally, polarization tests for the solder materials were carried out to determine ECM characteristics. Pb was found to be more susceptible to polarization than Sn, which matched the composition distribution of the conductive anodic filament on the PCB surface
[en] In a experimental plot of irrigated table grapes twelve neutron tubes were installed in each of two irrigated basins. Calibration of the neutron probe was done by the regression of the count ratio (R) on the volumetric water content (θv). To check the accuracy of the slope of the calibration equation a comparison of the soil water changes expected after known additions of water to soil by rainfall or irrigation with those changes measured with the neutron probe was made. This comparison showed that the neutron probe method on average overestimated the water change by about 22%. This overestimation is attributed to the type of regression used. An alternative method is proposed consisting in taking the mean value between the slope calculated from the regression of R on θv and then solving for θv, and that calculated from the regression of θv on R. It is suggested that measurement of the change in soil water content after a rainfall can be, under certain conditions, an easy way of testing the accuracy of the slope of the calibration equation