Force Barrier for Lipid Sorting in the Formation of Membrane Nanotubes

2019 ◽  
Vol 86 (12) ◽  
Author(s):  
Xingyi Tang ◽  
Jianxiang Wang ◽  
Xin Yi
Keyword(s):  
Coupling Effect ◽  
Early Stage ◽  
Membrane Extraction ◽  
Membrane Composition ◽  
Bending Rigidity ◽  
Lipid Sorting ◽  
Membrane Tubulation ◽  
Membrane Bending ◽  
Tension Increase ◽  
Pulling Force

Abstract Understanding lipid sorting of multicomponent cell membranes associated with tubular deformation is of essential importance to many cell activities such as filopodial growth and protein-mediated vesiculation. Here, we conduct theoretical analysis to investigate how the membrane tubulation induced by an external pulling force over a finite region is regulated by the coupling between the lipid composition and the membrane bending rigidity and tension. It is shown that the presence of the lipid-disordered phase facilitates the nanotube formation by reducing the force barrier. As the pulling region size and the membrane tension increase, the membrane tubulation becomes discontinuous regardless of the coupling effect. The direct proportional relationships between the maximum pulling force and size of pulling region at different coupling scenarios are identified. Analytical solutions for the linear force-extraction relation and the membrane configurations in the early stage of the membrane extraction are obtained. Our results indicate that in the case of a relatively small pulling region, the coupling between the membrane composition and mechanical properties plays an important role in regulating the membrane extraction, and such an effect due to the phase separation diminishes gradually as the pulling region enlarges and the force barrier becomes dominated by a large pulling region.

scholarly journals Chloride Diffusion Property of Hybrid Basalt–Polypropylene Fibre-Reinforced Concrete in a Chloride–Sulphate Composite Environment under Drying–Wetting Cycles

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1138
Author(s):  
Yang Luo ◽  
Ditao Niu ◽  
Li Su
Keyword(s):  
Reinforced Concrete ◽  
Coupling Effect ◽  
Early Stage ◽  
Polypropylene Fibre ◽  
Chloride Diffusion ◽  
Fibre Reinforcement ◽  
Fibre Reinforced Concrete ◽  
Basalt Fibre ◽  
Diffusion Property ◽  
Chloride Attack

The effect of fibre reinforcement on the chloride diffusion property of concrete is controversial, and the coupling effect of sulphate erosion and drying–wetting cycles in marine environments has been neglected in previous studies. In this study, the chloride diffusion property of hybrid basalt–polypropylene fibre-reinforced concrete subjected to a combined chloride–sulphate solution under drying–wetting cycles was investigated. The effects of basalt fibre (BF), polypropylene fibre (PF), and hybrid BP–PF on the chloride diffusion property were analysed. The results indicate that the presence of sulphate inhibits the diffusion of chloride at the early stage of erosion. However, at the late stage of erosion, sulphate does not only accelerate the diffusion of chloride by causing cracking of the concrete matrix but also leads to a decrease in the alkalinity of the pore solution, which further increases the risk of corrosion of the reinforcing steel. An appropriate amount of fibre can improve the chloride attack resistance of concrete at the early stage. With the increase in erosion time, the fibre effectively prevents the formation and development of sulphate erosion microcracks, thus reducing the adverse effects of sulphate on the resistance of concrete to chloride attack. The effects of sulphate and fibre on the chloride diffusion property were also elucidated in terms of changes in corrosion products, theoretical porosity, and the fibre-matrix interface transition zone.

scholarly journals Combustion Kinetics Characteristics of Solid Fuel in the Sintering Process

Processes ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 475
Author(s):  
Jihui Liu ◽  
Yaqiang Yuan ◽  
Junhong Zhang ◽  
Zhijun He ◽  
Yaowei Yu
Keyword(s):  
Iron Oxide ◽  
Coupling Effect ◽  
Early Stage ◽  
Combustion Process ◽  
Fuel Combustion ◽  
Particle Structure ◽  
Quasi Particle ◽  
Combustion Performance ◽  
Reduction Of Iron ◽  
Fuel Particles

In order to systematically elucidate the combustion performance of fuel during sintering, this paper explores the influence of three factors, namely coal substitution for coke, quasi-particle structure and the coupling effect with reduction and oxidation of iron oxide, on fuel combustion characteristics, and carries out the kinetic calculation of monomer blended fuel (MBF) and quasi-granular fuel (QPF). The results show that replacing coke powder with anthracite can accelerate the whole combustion process. MBF and QPF are more consistent with the combustion law of the double-parallel random pore model. Although the quasi-particle structure increases the apparent activation energy of fuel combustion, it can also produce a heat storage effect on fuel particles, improve their combustion performance, and reduce the adverse effect of diffusion on the reaction process. In the early stage of reaction, the coupling between combustion of volatiles and reduction of iron oxide is obvious. The oxidation of iron oxide will occur again when the combustion reaction of fuel is weakened.

scholarly journals Impact of Sterol Tilt on Membrane Bending Rigidity in Cholesterol and 7DHC-Containing DMPC Membrane

2012 ◽  
Vol 102 (3) ◽  
pp. 413a
Author(s):  
George Khelashvili ◽  
Michael Rappolt ◽  
See-Wing Chiu ◽  
Georg Pabst ◽  
Daniel Harries
Keyword(s):  
Bending Rigidity ◽  
Membrane Bending ◽  
Dmpc Membrane

Research on Experiment and Technology of Emulsion Liquid Membrane Applied to H Acid Wastewater Treatment

2011 ◽  
Vol 233-235 ◽  
pp. 394-398
Author(s):  
Li Zhang ◽  
Yao Ding
Keyword(s):  
Liquid Membrane ◽  
Removal Rate ◽  
Membrane Extraction ◽  
Operating Parameters ◽  
Membrane Composition ◽  
Total Removal ◽  
Countercurrent Extraction ◽  
Liquid Membrane Extraction ◽  
External Phase ◽  
Cod Removal Rate

In this experiment, we use the removal rate of COD as index to optimize membrane composition and operating parameters formula by 3 stage countercurrent liquid membrane extraction and also study the influence of different water to emulsion Rew on COD removal rate .The experiments showed that Rew and the external phase pH have significant effects on the removal rate of COD and the total removal rate of COD reached 85.3% when Rew=1:1.0 under the condition of 3 stage countercurrent extraction.

scholarly journals Membrane stiffness is a key determinant of E coli MscS channel mechanosensitivity

2019 ◽  
Author(s):  
Feng Xue ◽  
Charles D. Cox ◽  
Navid Bavi ◽  
Paul R Rohde ◽  
Yoshitaka Nakayama ◽  
...  
Keyword(s):  
Response Curve ◽  
Membrane Lipids ◽  
Bending Rigidity ◽  
Rightward Shift ◽  
E Coli ◽  
Tension Response ◽  
Global Properties ◽  
Membrane Stiffness ◽  
Membrane Bending ◽  
Branched Chain

AbstractProkaryotic mechanosensitive (MS) channels have an intimate relationship with membrane lipids. Membrane lipids may influence channel activity by directly interacting with bacterial MS channels or by influencing the global properties of the membrane such as area stretch and bending moduli. Previous work has implicated membrane stiffness as a key determinant of the mechanosensitivity of E. coli (Ec)MscS. Here we systematically tested this hypothesis using patch fluorometry of azolectin liposomes doped with lipids of increasing area stretch moduli. Increasing DOPE content of azolectin liposomes causes a rightward shift in the tension response curve of EcMscS. These rightward shifts are further magnified by the addition of stiffer forms of PE such as the branched chain lipid DPhPE and the fully saturated lipid DSPE. Furthermore, a comparison of the branched chain lipid DPhPC to the stiffer DPhPE showed a rightward shift in the tension response curve in the presence of the stiffer DPhPE. We show that these changes are not due to changes in membrane bending rigidity as the tension threshold of EcMscS in membranes doped with PC18:1 and PC18:3 are the same, despite a two-fold difference in their bending rigidity. We also show that after prolonged pressure application sudden removal of force in softer membranes causes a rebound reactivation of EcMscS and we discuss the relevance of this phenomenon to bacterial osmoregulation. Collectively, our data demonstrate that membrane stiffness is a key determinant of the mechanosensitivity of EcMscS.

Objective comparison of the softness of Australian Soft Rolling Skin wool and ordinary Merino wool

2021 ◽  
pp. 004051752110428
Author(s):  
Hao Yu ◽  
Christopher Hurren ◽  
Xin Liu ◽  
Xungai Wang
Keyword(s):  
Ethical Issue ◽  
Compression Test ◽  
Surface Friction ◽  
Test Results ◽  
Bending Rigidity ◽  
Compression Method ◽  
Merino Wool ◽  
Key Factor ◽  
Pulling Force ◽  
Australian Merino

Australian Merino wool is well-known in the wool market for its top quality, and the bulk of it is used in apparel where softness is a key factor for consumers. However, the ethical issue of mulesing is driving textile manufacturers and retailers to purchase non-mulesed wool from other sources instead of Australian mulesed wool. Australian Soft Rolling Skin (SRS) wool, grown on non-mulesed sheep, has been perceived to have a softer handle than ordinary Merino (OM) of the same diameter. In this research, three different methods were deployed to objectively compare the softness of SRS and OM wool. The force required to pull a bundle of clean wool through a series of parallel pins, that is, the pulling force, was used to evaluate the combined effect of fiber bending rigidity and surface friction. SRS wool resulted in lower pulling force than OM wool, with a difference of 15 cN/ktex (approximately 12.5%). According to the Resistance to Compression test results, SRS wool (4.5–5.7 kPa) was easier to compress than OM wool (5.4–6.5 kPa). The modified Resistance to Compression method showed different compression profiles for the two types of wool, and the slope of the decreasing curve (SDC) was used to study the softness property, with lower SDC values representing softer handle. These results confirm that over a fixed diameter range the SRS wool was more compressible and flexible, and this should result in a softer handle for clothing made from the fiber.

EFFECT OF MEMBRANE BENDING STIFFNESS ON THE DEFORMATION OF ELASTIC CAPSULES IN EXTENSIONAL FLOW: A LATTICE BOLTZMANN STUDY

2007 ◽  
Vol 18 (08) ◽  
pp. 1277-1291 ◽  
Author(s):  
Y. SUI ◽  
Y. T. CHEW ◽  
P. ROY ◽  
H. T. LOW
Keyword(s):  
Lattice Boltzmann ◽  
Present Model ◽  
Extensional Flow ◽  
Bending Stiffness ◽  
Immersed Boundary ◽  
Two Dimensional ◽  
Bending Rigidity ◽  
Elastic Membranes ◽  
Membrane Bending ◽  
Boltzmann Method

The transient deformation of liquid capsules enclosed by elastic membranes in two-dimensional extensional flow is studied numerically, using an improved immersed boundary-lattice Boltzmann method. The purpose of the present study is to investigate the effect of interfacial bending stiffness on the deformation of such capsules, under the subcritical elasticity capillary number conditions. The present model can simulate flow-induced deformation of capsules with arbitrary resting shapes (concerning the in-plane tension) and bending-free configurations. The deformation of capsules with initially circular, elliptical, and biconcave resting shapes was investigated in the present study; the capsules' bending-free configurations were considered as either circular shapes or their initially resting shapes. The results show that for capsules with bending-free configuration as circles, membrane bending rigidity has significant rounding effect on the steady deformed profiles. For elliptical and biconcave capsules with resting shapes as the bending-free configurations, it is found that with the bending stiffness increasing, the capsules' steady shapes are more akin to their initial shapes.

Molecular Origin of Model Membrane Bending Rigidity

2007 ◽  
Vol 98 (25) ◽  
Author(s):  
Erol Kurtisovski ◽  
Nicolas Taulier ◽  
Raymond Ober ◽  
Marcel Waks ◽  
Wladimir Urbach
Keyword(s):  
Model Membrane ◽  
Bending Rigidity ◽  
Molecular Origin ◽  
Membrane Bending
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