Stability of the Interface Between Two Immiscible Liquids in a Model Eye Subject to Saccadic Motion

2021 ◽  
Author(s):  
Ru Wang ◽  
Jheng-han Tsai ◽  
Martin Snead ◽  
Philip Alexander ◽  
D. Ian Wilson
Keyword(s):  
Weber Number ◽  
3D Model ◽  
Silicone Oil ◽  
Dynamics Simulation ◽  
Saccade Amplitude ◽  
Computational Fluid Dynamics Simulation ◽  
Immiscible Liquids ◽  
Bulk Fluid ◽  
The Stability ◽  
Particle Imaging

Abstract The interface between silicone oil and saline layers in a 3D model of the eye chamber was studied under different eye-like saccadic motions in order to determine the stability of the interface and propensity for emulsification in the bulk. The effect of level of fill; saccade amplitude, angular velocity, latency time; and orientation were investigated experimentally in spherical flasks with internal diameters 10, 28 and 40 mm, as well as a 28 mm diameter flask with an indent replicating the lens or the presence of a buckle. The deformation of the interface was quantified in terms of the change in its length in 2-D images. The deformation increased with Weber number, We, and was roughly proportional to We for We > 1. The presence of the lens gave rise to higher deformation near this feature. In both cases emulsification was not observed in either bulk fluid. The velocity profile in the spherical configuration was mapped using particle imaging velocimetry and is compared with an analytical solution and a short computational fluid dynamics simulation study. These confirm that the saccadic motion induces flow near the wall in the saline layer and significantly further into the chamber in the silicone oil. Surfactants soluble in the aqueous and oil phases reduced the interfacial tension, increasing deformation but did not lead to emulsification in the bulk.

scholarly journals CFD Simulation of Defogging Effectivity in Automotive Headlamp

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2609
Author(s):  
Michal Guzej ◽  
Martin Zachar
Keyword(s):  
Traffic Safety ◽  
3D Model ◽  
Cfd Simulation ◽  
Dew Point ◽  
Dynamics Simulation ◽  
Ambient Conditions ◽  
Computational Fluid Dynamics Simulation ◽  
The Past ◽  
Direct Exposure ◽  
Technical Solutions

In the past decade, the condensation of internal air humidity in automotive headlamps has become more prevalent than ever due to the increased usage of a new light source—LEDs. LEDs emit far less heat than previously-used halogen lamps, which makes them far more susceptible to fogging. This fogging occurs when the internal parts of the headlamp fall to a temperature below the dew point. The front glass is most vulnerable to condensation due to its direct exposure to ambient conditions. Headlamp fogging leads to a decrease in performance and the possibility of malfunctions, which has an impact not only on the functional aspect of the product’s use but also on traffic safety. There are currently several technical solutions available which can determine the effectivity of ventilation systems applied for headlamp defogging. Another approach to this problem may be to use a numerical simulation. This paper proposes a CFD (computational fluid dynamics) simulation with a slightly simplified 3D model of an actual headlamp, which allows simulation of all the phenomena closely connected with fluid flow and phase change. The results were validated by real experiments on a special fogging–defogging test rig. This paper compares three different simulations and their compliance with real experiments.

Functional characterization and structural modelling of peptidoglycan degrading β-N-acetyl-glucosaminidase from a dental isolate of Serratia marcescens

2020 ◽  
Vol 23 ◽  
Author(s):  
Aditi Rathee ◽  
Anil Panwar ◽  
Seema Kumari ◽  
Sanjay Chhibber ◽  
Ashok Kumar
Keyword(s):  
Functional Characterization ◽  
Major Change ◽  
Crystal Form ◽  
Bound State ◽  
Dynamics Simulation ◽  
Gram Positive ◽  
Structural Cell ◽  
Stability Structure ◽  
Arginine Residues ◽  
The Stability

Introduction:: Enzymatic degradation of peptidoglycan, a structural cell wall component of Gram-positive bacteria, has attracted considerable attention being a specific target for many known antibiotics. Methods:: Peptidoglycan hydrolases are involved in bacterial lysis through peptidoglycan degradation. β-N-acetylglucosaminidase, a peptidoglycan hydrolase, acts on O-glycosidic bonds formed by N-acetylglucosamine and N-acetyl muramic acid residues of peptidoglycan. Aim of present study was to study the action of β-N-acetylglucosaminidase, on methicillin- resistant Staphylococcus aureus (MRSA) and other Gram-negative bacteria. Results:: We investigated its dynamic behaviour using molecular dynamics simulation and observed that serine and alanine residues are involved in catalytic reaction in addition to aspartic acid, histidine, lysine and arginine residues. When simulated in its bound state, the RMSD values were found lesser than crystal form in the time stamp of 1000 picoseconds revealing its stability. Structure remained stably folded over 1000 picoseconds without undergoing any major change further confirming the stability of complex. Conclusion:: It can be concluded that enzymes belonging to this category can serve as a tool in eradicating Gram-positive pathogens and associated infections.

scholarly journals Rational thermostabilisation of four-helix bundle dimeric de novo proteins

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shin Irumagawa ◽  
Kaito Kobayashi ◽  
Yutaka Saito ◽  
Takeshi Miyata ◽  
Mitsuo Umetsu ◽  
...  
Keyword(s):  
Protein Design ◽  
De Novo ◽  
Protein Complexes ◽  
Salt Bridge ◽  
Dynamics Simulation ◽  
Saturation Mutagenesis ◽  
Helix Bundle ◽  
Stable Mutant ◽  
Four Helix Bundle ◽  
The Stability

AbstractThe stability of proteins is an important factor for industrial and medical applications. Improving protein stability is one of the main subjects in protein engineering. In a previous study, we improved the stability of a four-helix bundle dimeric de novo protein (WA20) by five mutations. The stabilised mutant (H26L/G28S/N34L/V71L/E78L, SUWA) showed an extremely high denaturation midpoint temperature (Tm). Although SUWA is a remarkably hyperstable protein, in protein design and engineering, it is an attractive challenge to rationally explore more stable mutants. In this study, we predicted stabilising mutations of WA20 by in silico saturation mutagenesis and molecular dynamics simulation, and experimentally confirmed three stabilising mutations of WA20 (N22A, N22E, and H86K). The stability of a double mutant (N22A/H86K, rationally optimised WA20, ROWA) was greatly improved compared with WA20 (ΔTm = 10.6 °C). The model structures suggested that N22A enhances the stability of the α-helices and N22E and H86K contribute to salt-bridge formation for protein stabilisation. These mutations were also added to SUWA and improved its Tm. Remarkably, the most stable mutant of SUWA (N22E/H86K, rationally optimised SUWA, ROSA) showed the highest Tm (129.0 °C). These new thermostable mutants will be useful as a component of protein nanobuilding blocks to construct supramolecular protein complexes.

scholarly journals Comparison of Downdraught and Up Draft Passive Air Conduction Systems (PACS) in a Winery Building

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 259
Author(s):  
Ádám László Katona ◽  
István Ervin Háber ◽  
István Kistelegdi
Keyword(s):  
Air Conditioning ◽  
Natural Ventilation ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation ◽  
General Applicability ◽  
Change Rate ◽  
Air Change Rate ◽  
Simulation Based ◽  
Ventilation Performance ◽  
Air Conduction

A huge portion of energy consumption in buildings comes from heating, ventilation, and air conditioning. Numerous previous works assessed the potential of natural ventilation compared to mechanical ventilation and proved their justification on the field. Nevertheless, it is a major difficulty to collect enough information from the literature to make decisions between different natural ventilation solutions with a given situation and boundary conditions. The current study tests the passive air conduction system (PACS) variations in the design phase of a medium-sized new winery’s cellar and production hall in Villány, Hungary. A computational fluid dynamics simulation based comparative analysis enabled to determine the differences in updraft (UD) and downdraught (DD) PACS, whereby the latter was found to be more efficient. While the DD PACS performed an air change range of 1.02 h−1 to 5.98 h−1, the UD PACS delivered −0.25 h−1 to 12.82 h−1 air change rate. The ventilation performance of the DD version possessed lower amplitudes, but the distribution was more balanced under different wind incident angles, thus this version was chosen for construction. It could be concluded that the DD PACS provides a more general applicability for natural ventilation in moderate climates and in small to medium scale industry hall domains with one in- and one outlet.

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