Application Of Seeding Crystallization as a Pre-Treatment Stage for The Reduction of Scaling Tendency of Seawater Feed to Thermal Desalination Units

Objective: The fouling inhibition in seawater desalination and scale control using crystallization with calcite seeds is evaluated experimentally in this study. Methods: The growth kinetic parameters are determined experimentally, correlated and discussed at different operating conditions. Supersaturation levels represent driving force behind the growth of crystals, which is influenced directly by seawater pH values and temperatures. Results: Results indicate that the initial pH value of seawater must be controlled to be in the range (8-9) and calcite seeds will not have the potential to start the growth process in seawater at the normal pH (7.36). The growth kinetic parameters are determined from the measured desupersaturation curves. Conclusion: It is found that the growth process of calcite is controlled by the surface integration step. The growth rate of calcite increases with increasing temperature and seeding ratio (up to 1 g/L), while it decreases with increasing the salinity of seawater.

How stable are the collagen and ferritin proteins for application in bioelectronics?

One major obstacle in development of biomolecular electronics is the loss of function of biomolecules upon their surface-integration and storage. Although a number of reports on solid-state electron transport capacity of proteins have been made, no study on whether their functional integrity is preserved upon surface-confinement and storage over a long period of time (few months) has been reported. We have investigated two specific cases—collagen and ferritin proteins, since these proteins exhibit considerable potential as bioelectronic materials as we reported earlier. Since one of the major factors for protein degradation is the proteolytic action of protease, such studies were made under the action of protease, which was either added deliberately or perceived to have entered in the reaction vial from ambient environment. Since no significant change in the structural characteristics of these proteins took place, as observed in the circular dichroism and UV-visible spectrophotometry experiments, and the electron transport capacity was largely retained even upon direct protease exposure as revealed from the current sensing atomic force spectroscopy experiments, we propose that stable films can be formed using the collagen and ferritin proteins. The observed protease-resistance and robust nature of these two proteins support their potential application in bioelectronics.

Bioassemblying Macro-Scale, Lumnized Airway Tubes of Defined Shape via Multi-Organoid Patterning and Fusion

Epithelial, stem-cell derived organoids are ideal building blocks for tissue engineering, however, scalable and shape-controlled bioassembly of epithelial organoids into larger and anatomical structures has yet to be achieved. Here, a robust organoid engineering approach, Multi-Organoid Patterning and Fusion (MOrPF), is presented to assemble individual airway organoids of different sizes into upscaled, scaffold-free airway tubes with pre-defined shapes. Multi-Organoid Aggregates (MOAs) undergo accelerated fusion in a matrix-depleted, free-floating environment, possess a continuous lumen and maintain prescribed shapes without an exogenous scaffold interface. MOAs in the floating culture exhibit a well-defined three-stage process of inter-organoid surface integration, luminal material clearance and lumina connection. The observed shape stability of patterned MOAs is confirmed by theoretical modelling based on organoid morphology and the physical forces involved in organoid fusion. Immunofluorescent characterization shows that fused MOA tubes possess an unstratified epithelium consisting mainly of tracheal basal stem cells. By generating large, shape-controllable organ tubes, MOrPF enables upscaled organoid engineering towards integrated organoid-devices and structurally complex organ tubes.

Deterministic normal contact of rough surfaces with adhesion using a surface integral method

The fundamental problem of adhesion in the presence of surface roughness and its effect on the prediction of friction has been a hot topic for decades in numerous areas of science and engineering, attracting even more attention in recent years in areas such as geotechnics and tectonics, nanotechnology, high-value manufacturing and biomechanics. In this paper a new model for deterministic calculation of the contact mechanics for rough surfaces in the presence of adhesion is presented. The contact solver is an in-house boundary element method that incorporates fast Fourier transform for numerical efficiency. The adhesive contact model considers full Lennard-Jones potentials and surface integration at the asperity level and is validated against models in the literature. Finally, the effect of surface roughness on the adhesion between surfaces was studied, and it was shown that the root mean square gradient of surface roughness can change the adhesive pressures irrespective of the root mean square surface roughness. We have tested two adhesion parameters based on Johnson's modified criteria and Ciavarella's model. We showed that Civarella's model introduces the most reasonable criteria suggesting that the RMS roughness and large wavelength of surfaces roughness are the important parameters of adhesion between rough surfaces.

Inaccurate Space Perception Seeing Through Fences

According to the sequential surface integration process hypothesis, the fine near-ground-surface representation and the homogeneous ground surface play a vital role in the representation of the ground surface. When an occluding box or opaque wall is placed between observers and targets, observers underestimate egocentric distance. However, in our daily life, many obstacles are perforated and cover the ground surface and targets simultaneously (e.g., fences). Humans see and observe through fences. The images of these fences and targets, projected onto observers’ retinas, overlap each other. This study aims to explore the effects of perforated obstacles (i.e., fences) on space perception. The results showed that observers underestimated the egocentric distances when there was a fence on the ground surface relative to the no-fence condition, and the effect of widely spaced thick wood fences was larger than that of narrowly spaced thin iron fences. We further demonstrated that this effect was quite robust when the target size had a visual angle of 1°, 2°, or 4° in three virtual reality experiments. This study may add support for the notion that the sequential surface integration process hypothesis is applicable even if the obstacle is perforated and covers the target.