Friction and Wetting Transitions of Magnetic Droplets on Micropillared Superhydrophobic Surfaces

Reliable characterization of wetting properties is essential for the development and optimization of superhydrophobic surfaces. Here, the dynamics of superhydrophobicity is studied including droplet friction and wetting transitions by using droplet oscillations on micropillared surfaces. Analyzing droplet oscillations by high‐speed camera makes it possible to obtain energy dissipation parameters such as contact angle hysteresis force and viscous damping coefficients, which indicate pinning and viscous losses, respectively. It is shown that the dissipative forces increase with increasing solid fraction and magnetic force. For 10 µm diameter pillars, the solid fraction range within which droplet oscillations are possible is between 0.97% and 2.18%. Beyond the upper limit, the oscillations become heavily damped due to high friction force. Below the lower limit, the droplet is no longer supported by the pillar tops and undergoes a Cassie–Wenzel transition. This transition is found to occur at lower pressure for a moving droplet than for a static droplet. The findings can help to optimize micropillared surfaces for low‐friction droplet transport.     

Performance and programmability comparison of the thick control flow architecture and current multicore processors

The Journal of Supercomputing - Commercial multicore central processing units (CPU) integrate a number of processor cores on a single chip to support parallel execution of computational tasks....     

Emission measurements with gravimetric impactors and electrical devices: An aerosol instrument comparison

Particulate matter in the atmosphere is known to affect Earth’s climate and to be harmful to human health. Accurately measuring particles from emission sources is important, as the results are used to inform policies and climate models. This study compares the results of two ELPI?+?devices, two PM10 cascade impactors and an eFilter, in combustion emission measurements. The comparison of the instruments in a realistic setting shows what types of challenges arise from measuring an emission aerosol with unknown particle morphologies and densities, different particle concentrations and high temperature. Our results show that the PM10 cascade impactors have very good intercorrelation when the collected mass is greater than 150?µg, but below that, the uncertainty of the results increases with decreasing mass. The raw signals of two ELPI?+?devices were nearly identical in most samples, as well as the particle number concentrations and size distributions calculated from raw signals; however, transforming the current distributions into mass distributions showed variation in the mass concentration of particles larger than 1?µm. The real-time time signal measured by eFilter was similar to the total current measured by ELPI+. The eFilter and PM10 cascade impactors showed similar particle mass concentrations, whereas ELPI?+?showed clearly higher ones in most cases. We concluded that the difference is at least partially due to volatile components being measured by ELPI+, but not by the mass collection measurements.

Copyright © 2019 American Association for Aerosol Research     

Cu–H-MCM-41, H-MCM-41 and Na-MCM-41 Mesoporous Molecular Sieve Catalysts for Isomerization of 1-Butene to Isobutene

Cu–H-MCM-41, H-MCM-41 and Na-MCM-41 mesoporous molecular sieve catalysts were synthesized, characterized and investigated in the isomerization of 1-butene to isobutene. Introduction of copper in MCM-41 was found to play a positive role in enhancing the conversion of 1-butene and yield of isobutene and Cu–H-MCM-41 exhibited higher conversion of 1-butene and yield to isobutene than H-MCM-41 and Na-MCM-41 catalysts. The pretreatments of Cu–H-MCM-41 catalyst with synthetic air or hydrogen were observed to influence the 1-butene conversion, yield of isobutene and selectivity to isobutene. Pre-treated with the synthetic air the Cu–H-MCM-41-Ox catalyst exhibited higher conversion of 1-butene, yield of isobutene and selectivity to isobutene than hydrogen pre-treated Cu–H-MCM-41-Red. The reason for such a behavior of Cu–H-MCM-41-Red is the reduction of copper species to metallic form. The X-ray powder diffraction pattern of Cu–H-MCM-41-Red exhibited a peak attributed to the reduction of Cu²⁺ to Cu⁰. FTIR spectra of adsorbed pyridine showed the presence of Brønsted and Lewis acid sites in the H-MCM-41, Na-MCM-41 and Cu–H-MCM-41 catalysts.     

Variation and directional anisotropy of reflectance at the crown scale — Implications for tree species classification in digital aerial images

Tree species classification is still solved at insufficient reliability in airborne optical data. The variation caused by directional reflectance anisotropy hampers image-based solutions. In addition, trees show considerable within-species variation in reflectance properties. We examined these phenomena at the single-tree level, using the Leica ADS40 line sensor and XPro software, which constitute the first photogrammetric large-format multispectral system to provide target reflectance images. To analyze the influence of illumination conditions in the canopy, we developed a method in which the crown shape as well as between-tree occlusions and shading were modeled, using dense LiDAR data. The precision of the ADS40 reflectance images in well-defined surfaces was 5% as coefficient of variation when 1−4-km image data were fused. The range of reflectance anisotropy was ± 30% for trees near the solar principal plane, with differences between bands and species. Because of the anisotropy differences observed, the spectral separability of the tree species in different bands is dependent on the view-illumination geometry. The within-species variation was high; the coefficient of variation was 13−31%. The contribution of tree and stand variables to anisotropy-normalized reflectance variation was examined. The effects of the species composition of adjacent trees were substantial in NIR and this variation hampers spectral classification in mixed stands. We also studied species- and band-specific intracrown brightness patterns, and we suggest their use as high-order image features in species classification. A species classification accuracy of up to 80% was obtained using 4-km data, which showed the high potential of the ADS40.     

Semi-Automated,Large-Scale Evaluation of Public Displays

This article presents a scalable, semi-automated process for studying the usage of public displays. The process consists of gathering anonymous interaction and skeletal data of passersby during public display deployment and programmatically analyzing the data. This article demonstrates the use of the process with the analysis of the Information Wall, a gesture-controlled public information display. Information Wall was deployed in a university campus for one year and collected an extensive data set of more than 100 000 passersby. The main benefits of the process include (1) gathering of large data sets without considerable use of resources, (2) fast, semi-automated data analysis, and (3) applicability to studying the effects of long-term public display deployments. In analyzing the usage and passersby data of the Information Wall in our validation study, the main findings uncovered using the method were (i) most users were first-time users exploring the system, and not many returned to use the system again, and (ii) many users were accompanied by passive users who observed interaction from further away, which could suggest a case of multi-user interaction blindness. In the past, logged data has mainly been used as a supporting method for in situ observations and interviews, and its use has required a considerable amount of manual work. In this article, we argue that logged data analysis can be automated to complement other methods, particularly in the evaluation of long-term deployments.     

Inkjetting dielectric layer for electronic applications

Printed electronics is expected to increase its market share significantly in near future. The emerging applications include e.g. display applications, RFID tags, and photovoltaic applications. A benefit of printing is the additive character of the process, which means that material is deposited only the amount that is needed. Digital printing increases flexibility of the process, because circuits are manufactured directly from a digital file, which removes need of fixed masks or patterned screens for each layout. Formation of a multilayer circuitry requires printing of conductive and insulative layers. This paper focuses on printing of a dielectric layer with an inkjet printer. Six sigma DMAIC approach was applied during the process characterization and analysis. The study began by defining the process parameters and evaluating their importance to the outputs. Highest rated parameters were taken into consideration and a design of experiments was established. Measured values were analyzed and it was observed which parameters had the highest effect on the outputs. The results were further verified and it was observed that electrically the printed structures were successful.     

[FeFe]-hydrogenase gene quantification and melting curve analysis from hydrogen-fermenting bioreactor samples

In this study, quantitative PCR (qPCR) was used to quantify [FeFe]-hydrogenases and subsequently melting curves were analyzed from hydrogen-fermenting, mixed-culture bioreactor samples. Denaturing gradient gel electrophoresis (DGGE) analysis was also performed to the reactor samples revealing a clostridial dominance in the reactor. Primers targeting [FeFe]-hydrogenases were designed based on known clostridial [FeFe]-hydrogenase gene sequences and tested with several clostridial strains. The results show that amplification efficiencies of four different clostridia are highly similar and melting curves of the clostridial strains were within 1 °C of each other. We compared the melting curves to the hydrogen percentage and observed a correlation between the results. The closer the melting curves were to those of clostridia, the better the hydrogen production. Based on these results, the primers and melting curve analysis of [FeFe]-hydrogenase amplicons can be used for analysing hydrogenase genes from bioreactor samples.