capillary bridge
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2021 ◽  
Vol 118 (33) ◽  
pp. e2102449118
Author(s):  
Romain Bey ◽  
Benoit Coasne ◽  
Cyril Picard

By considering a water capillary bridge confined between two flat surfaces, we investigate the thermodynamics of the triple line delimiting this solid–liquid–vapor system when supplemented in carbon dioxide. In more detail, by means of atom-scale simulations, we show that carbon dioxide accumulates at the solid walls and, preferably, at the triple lines where it plays the role of a line active agent. The line tension of the triple line, which is quantitatively assessed using an original mechanical route, is shown to be driven by the line excess concentrations of the solute (carbon dioxide) and solvent (water). Solute accumulation at the lines decreases the negative line tension (i.e., more negative) while solvent depletion from the lines has the opposite effect. Such an unprecedented quantitative assessment of gas-induced line tension modifications shows that the absolute value of the negative line tension increases upon increasing the carbon dioxide partial pressure. As a striking example, for hydrophilic surfaces, the line tension is found to increase by more than an order of magnitude when the carbon dioxide pressure exceeds 3 MPa. By considering the coupling between line and surface effects induced by gaseous adsorption, we hypothesize from the observed gas concentration-dependent line tension a nontrivial impact on heterogeneous nucleation of nanometric critical nuclei.


2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
A Machowetz ◽  
O Shebl ◽  
M Maurer ◽  
T Ebner ◽  
H C Duba

Abstract Study question Influence of sperm selector separation of sperms on their translocation load, segregation pattern, motility and occurrence of interchromosomal effects Summary answer Sperm selector separation led to reduction of the translocation load, shift in segregation pattern and lower rates of interchromosomal effects within sperm samples What is known already Balanced translocations in men are known to be one of the main causes of reproductive failure. The segregation pattern in sperms is determined by the distribution of the chromosomes during meiosis. Interchromosomal effects can also influence the distribution of chromosomes that are not involved in the translocation. The sperm selector used consists of two concentric chambers, which are overlaid by a U-ring and a cover glass. Motile sperms migrate from the native ejaculate in the medium filled inner chamber by using a capillary bridge created by the U-ring. This avoids potential harmful centrifugation and allows accumulation of motile sperms. Study design, size, duration Twenty-one carriers of balanced translocations participated in the study. In addition, 15 patients were involved as control. All participants signed an informed consent (F–8–15). Samples of three patients did not meet the internal quality criteria and had to be excluded from analysis. The study started in 2015 and is still ongoing. Participants/materials, setting, methods Liquefied native ejaculate was processed with a sperm selector. Native ejaculate, non-migrated sperms from the outer chamber and migrated sperms from the inner chamber were transferred onto glass slides, fixed and underwent a decondensation treatment. For segregation analysis FISH translocation specific FISH probe mixes were used and tested on patient’s blood. Interchromosomal effects were analysed with FISH probes for the chromosomes X, Y, 18 and 13, 21. Evaluation was done manually using fluorescence microscopy. Main results and the role of chance Segregation analysis was done for more than 25,000 sperms from men carrying a balanced translocation (18 patients with reciprocal and 3 patients with Robertsonian translocation). Separation via sperm selector led to a reduction in translocation load (native to separated approach 49,1±11,5% to 34,8±9,4% (P = <0,01), the rate depending on the specific translocation. There was also a shift in the segregation pattern, which seemed to be influenced by the specific translocation and the resulting steric alignment of the corresponding quadrivalent / trivalent. Additionally, more than 90,000 sperms from patients with balanced translocations were analysed for interchromosomal effects. Separation led to reduced maldistribution rate (native to separated approach 7,1±3,5% to 5±3,1%, P = <0,01) whereas the steric alignment of the corresponding quadrivalent / trivalent seems to influence the interchromosomal effect as well. For control, sperms from control patients were analysed regarding the chromosomes X, Y, 18 and 13, 21. In about 90,000 control sperms separation led to reduced maldistribution rate (native to separated approach 5,4±1,5% to 3,8±1,1%; P = <0,01). Limitations, reasons for caution The number of accumulated strandbreak-free sperms depended on the motility and sperm count of the native ejaculate. Examinations are not reproducible, as each sample delivery is influenced by external circumstances Wider implications of the findings: Sperm selector separation can be used before ART to reduce the translocation load and rate of maldistribution in sperms from carriers of balanced translocations. This could have a considerable impact on PGT results after trophectoderm biops. Trial registration number Not applicable


2021 ◽  
Vol 23 (3) ◽  
Author(s):  
Halimeh Moharamkhani ◽  
Reza Sepehrinia ◽  
Mostafa Taheri ◽  
Morteza Jalalvand ◽  
Martin Brinkmann ◽  
...  

Author(s):  
Felix Platzer ◽  
Eric Fimbinger

AbstractMixtures of a fine-grained dry solid and a liquid, with a higher solid content in the mixture, show paste-like behaviour. In many technical processes, pasty materials are handled in large quantities. Pasty Materials show the same characteristics as Bingham Plastics, behaving like a rigid body but flowing like a viscous fluid under a certain stress level. This behaviour is due to attracting forces between the particles, resulting from the capillary pressure and the surface tension of the liquid, which forms individual capillary bridges or capillary bridge clusters between the solid particles. The behaviour of granular material can be represented in a discrete element method (DEM) simulation. The calibration of the simulation parameters is achieved by comparing laboratory tests, which reflect a typical material characteristic, with the results of calibration simulations. In this project, several DEM contact models, describing attractive forces between particles depending on the distance between them, were analysed and assessed based on their ability to display the pasty material behaviour of a fine-grained solid water mixture with a high water content by comparing the simulation results to a slump test. The most promising contact model was then optimised to enable a minimal computing time for the simulation of bigger technical processes. Many existing contact models also consider attractive forces between particles (e.g. JKR cohesion) but are based on different physical effects. For this reason, the contact models assessed in the course of this project are, in general, based on the capillary effect.


Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 285
Author(s):  
Zenghua Fan ◽  
Zixiao Liu ◽  
Congcong Huang ◽  
Wei Zhang ◽  
Zhe Lv ◽  
...  

The capillary action between two solid surfaces has drawn significant attention in micro-objects manipulation. The axisymmetric capillary bridges and capillary forces between a spherical concave gripper and a spherical particle are investigated in the present study. A numerical procedure based on a shooting method, which consists of double iterative loops, was employed to obtain the capillary bridge profile and bring the capillary force subject to a constant volume condition. Capillary bridge rupture was characterized using the parameters of the neck radius, pressure difference, half-filling angle, and capillary force. The effects of various parameters, such as the contact angle of the spherical concave gripper, the radius ratio, and the liquid bridge volume on the dimensionless capillary force, are discussed. The results show that the radius ratio has a significant influence on the dimensionless capillary force for the dimensionless liquid bridge volumes of 0.01, 0.05, and 0.1 when the radius ratio value is smaller than 10. The effectiveness of the theorical approach was verified using simulation model and experiments.


Friction ◽  
2021 ◽  
Author(s):  
Shuai Wu ◽  
Yuqing He ◽  
Quanshui Zheng ◽  
Ming Ma

AbstractThe presence of a capillary bridge between solid surfaces is ubiquitous under ambient conditions. Usually, it leads to a continuous decrease of friction as a function of bridge height. Here, using molecular dynamics we show that for a capillary bridge with a small radius confined between two hydrophilic elastic solid surfaces, the friction oscillates greatly when decreasing the bridge height. The underlying mechanism is revealed to be a periodic ordered-disordered transition at the liquid–solid interfaces. This transition is caused by the balance between the surface tension of the liquid–vapor interface and the elasticity of the surface. This balance introduces a critical size below which the friction oscillates. Based on the mechanism revealed, a parameter-free analytical model for the oscillating friction was derived and found to be in excellent agreement with the simulation results. Our results describe an interesting frictional phenomenon at the nanoscale, which is most prominent for layered materials.


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