Experimental Correlation for Splashing Condition of Droplets on Solid Substrates

Droplet splashing behaviors of water-ethanol binary mixture liquids on roughened solid surfaces were experimentally observed in order to investigate the effects of surface tension, viscosity, and wettability/surface roughness on the splashing occurrence. The range of the droplet volumes was from 1.7 μL to 32.6 μL. The ranges of the surface tension and the viscosity were from 21.1 mN/m to 71.9 mN/m, and from 1 mPas to 2.91 mPas, respectively. The surface roughness range was from 0.03 μm to 1.25 μm for Ra. The present experimental data were evaluated on the basis of the existing models. Resulting from these experiments, a simple model using the Ohnesorge number evaluated by the capillary length was proposed and the accuracy of the predicted critical values such as the critical Weber and Reynolds numbers were discussed. The result indicated that the liquid properties and the quantification of the surface condition such as surface roughness are important factors for the prediction of the splashing behavior.

Neutron Reflectometry-Based In Situ Structural Analysis of an Aligning Agent Additive for the Alignment of Nematic Liquid Crystals on Solid Substrates

Surface aligning agents, such as amphiphilic surfactants, are widely used to control the initial alignment of nematic liquid crystals (NLCs) in liquid crystal displays (LCDs). Generally, these agents are first...

Study of Langmuir monolayers and Langmuir-Schaefer films based on symmetrical meso-aryl-substituted porphyrin derivative

This paper presents the results of a study of meso-aryl-substituted porphyrin Langmuir monolayers by the method of compression isotherms. Experimental data were used to plot the dependences of the compression modulus (C−1) on the specific area. Monolayers at specific surface pressure were transferred to solid substrates and investigated. The monolayers were transferred to the surface of monocrystalline silicon at surface pressures of 8, 25, and 60 mN/m and examined them by atomic force microscopy (AFM) in a semi-contact mode. It was found that with an increase in the transfer pressure, the coarsening of molecular aggregates occurs. The smallest roughness is observed for a porphyrin film formed and transferred at a pressure of 8 mN/m.

Effect of common foods as supplements for the mycelium growth of Ganoderma lucidum and Pleurotus ostreatus on solid substrates

The transition from a linear to a circular economy is urgently needed to mitigate environmental impacts and loss of biodiversity. Among the many potential solutions, the development of entirely natural-based materials derived from waste is promising. One such material is mycelium-bound composites obtained from the growth of fungi onto solid lignocellulosic substrates, which find applications such as insulating foams, textiles, packaging, etc. During growth, the fungus degrades and digests the substrate to create a web-like stiff network called mycelium. The development of the mycelium is influenced by several factors, including the substrate composition. As food waste accounts for nearly 44% of total municipal solid waste, incorporating food in the substrate composition could be a means to increase the nutrients absorbed by the fungus. In this paper, we study the effects of the addition of food supplements on the growth of two fungal species, Ganoderma lucidum and Pleurotus ostreatus. The substrates, the food supplements, and the mycelia are characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and optical microscopy. Our results show that addition of barley as a supplement significantly boosts the growth of G. lucidum and P. ostreatus. Using a common food as a nutritious enrichment for the development of mycelium is a simple and straightforward strategy to create waste-based mycelium-bound biocomposites for a large range of applications, on-site, therefore promoting a circular economy.

Electrosynthesis of Biocompatible Free-Standing PEDOT Thin Films at a Polarised Liquid|Liquid Interface

The versatility of conducting polymers (CPs) facilitates their use in energy conversion and storage, sensor, and biomedical technologies, once processed into thin films. Hydrophobic CPs, like poly(3,4-ethylenedioxythiophene) (PEDOT), typically require the use of surfactant additives, such as poly(styrenesulfonate) (PSS), to aid their aqueous processability as thin films. However, excess PSS diminishes CP electrochemical performance, biocompatibility, and device stability. Here, we report the electrosynthesis of PEDOT thin films at a polarised liquid|liquid interface, a method non-reliant on conductive solid substrates that produces free-standing, additive-free, biocompatible, easily transferrable, and scalable 2D PEDOT thin films of any shape or size in a single-step at ambient conditions. We demonstrate the PEDOT thin film’s superior biocompatibility as scaffolds for cellular growth, opening immediate applications in organic electrochemical transistor (OECT) devices for monitoring cell behaviour over extended time periods, bio-scaffolds and medical devices, without the requirement for physiologically unstable and poorly biocompatible PSS.

A common computational principle for vibrotactile pitch perception in mouse and human

We live surrounded by vibrations generated by moving objects. These oscillatory stimuli propagate through solid substrates, are sensed by mechanoreceptors in our body and give rise to perceptual attributes such as vibrotactile pitch (i.e. the perception of how high or low a vibration’s frequency is). Here, we establish a mechanistic relationship between vibrotactile pitch perception and the physical properties of vibrations using behavioral tasks, in which vibratory stimuli were delivered to the human fingertip or the mouse forelimb. The resulting perceptual reports were analyzed with a model demonstrating that physically different combinations of vibration frequencies and amplitudes can produce equal pitch perception. We found that the perceptually indistinguishable but physically different stimuli follow a common computational principle in mouse and human. It dictates that vibrotactile pitch perception is shifted with increases in amplitude toward the frequency of highest vibrotactile sensitivity. These findings suggest the existence of a fundamental relationship between the seemingly unrelated concepts of spectral sensitivity and pitch perception.

Evaporation and deposition of inclined colloidal droplets

Colloidal droplets on flat solid substrates commonly leave symmetric ring-like deposits due to coffee-ring flows during evaporation. On inclined substrates, droplet shapes may become asymmetric by gravity. On this basis, it is not clear how their evaporation dynamics and final deposits are changed depending on inclination. Here we explore evaporation and deposition dynamics of colloidal droplets on inclined substrates, mainly by controlling colloidal particle size, substrate inclination, and relative humidity, which are crucial to gravitational intervention and evaporation dynamics. We experimentally investigate two different flows with opposite directions: downward sedimentation flows by gravity ($$v_s$$ v s ) and upward capillary flows by evaporation ($$v_c$$ v c ). We find that the competition of two flows determines the formation of final deposits with a flow speed ratio of $$\alpha = v_s/v_c$$ α = v s / v c . Notably, for $$\alpha$$ α $$\ll$$ ≪ 1, evaporation-driven upward flows overwhelm sedimentation-driven downward flows, resulting in accentuated particle movement towards the top ring, which seems to defy gravitational intervention. We suggest a possible explanation for the flow speed dependence of final deposits in evaporating colloidal droplets. This study offers a framework to understand the intervention of inclination to the formation of final deposits and how to overcome the deposit pattern radial asymmetry, achieving symmetric deposit widths from inclined colloidal droplets.

Photocatalytic Treatment of Different Types of High−Concentration Ammonia Wastewater by Cu/TiO2 Film and its Mechanism Study

Photocatalytic oxidation of ammonia in wastewater has been abundantly investigated in lab − scale, but there are still many issues to be solved towards practical application. Herein, we have immobilized Cu/TiO2 photocatalyst on different solid substrates in order to practically utilize and recycle the photocatalyst during wastewater treatment, on the basis of exploring the effects of different influencing factors such as pH, temperature and salinity on the photocatalytic oxidation of ammonia in this work. The performance of Cu/TiO2 films was evaluated by circulated treatment of different types of wastewater including high salinity ammonia wastewater, copper − ammonia wastewater and liquid − ammonia mercerization wastewater. The characters of wastewater matrices significantly influence the performance for ammonia oxidation. Different from the slurry test of photocatalyst power that operated in a closed reactor, it is importantly found that oxygen in air plays significant role in photocatalytic oxidation of ammonia into dinitrogen in the aerobic oxidation process, when the Cu/TiO2 films were employed. The possible oxidation mechanism has been proposed to elucidate the ammonia oxidation process.