Decrease In Curvature Research Articles

Shape recovery of the of nickelide titane plate

Shape memory alloys such as titanium nickelide are currently used in different fields of engineering, construction, and medicine, due to their unique ability to recover significant inelastic deformations upon heating. Titanium nickelide plates as structural elements or medical devices are exposed to complex temperature and force impacts during operation, which leads to a change in the stress-strain state of the material. For example, a plate rigidly clamped on one side significantly changes the surface curvature during thermal cycling under load or as a result of heating after preliminary plastic deformation. Similar exposures are implemented in the devices in which the plate is used as a sensitive element, for example, temperature sensors, electrical contacts, smart ailerons, etc. When designing these elements, it is important to take into account changes in such deformation parameters as curvature, deformation, and shape recovery coefficient. The lack of information on those parameters is observed for titanium nickelide plates. We present the results of the experimental study of the shape reduction of a titanium nickelide plate both during isothermal unloading after plastic deformation and during thermal cycling under the impact of a constant bending force. It is shown that plastic deformation of the plate under isothermal conditions with an increase in the initial radius of the curvature by 3.35 times leads to an increase in the curvature by 4.83 times after pseudoelastic unloading. It is shown that the shape memory effect after isothermal bending of a rectangular titanium nickelide plate increases as the prescribed radius of the curvature decreases. Moreover, the curvature under constant load changes during thermal cycling in a complex way. The results of the study can be used in designing devices based on titanium nickelide plates.

Evaluation of the spinal effects of phthalates in a zebrafish embryo assay

Phthalates (phthalate esters, PAEs) are commonly used as plasticizers and are emerging concerns worldwide for their potential influence on the environment and general public health. Thus, identification of the negative effects and involved mechanisms of PAEs is necessary. Herein, we found that embryonic exposure of zebrafish to di-(2-ethylhexyl) phthalate (DEHP) and di-butyl phthalate (DBP) significantly induced spinal defects, such as inhibited spontaneous movement at 24 h post-fertilization (hpf), spine curvature and body length decrease at 96 hpf. The transcriptional level of the genes that are related to the development of the notochord (col8a1a and ngs), muscle (stac3, klhl41a and smyd2b) and skeleton (bmp2, spp1) were significantly altered by DEHP and DBP at 50 and 250 μg/L, which might be associated with the observed morphological changes. Notably, DBP and DEHP altered the locomotor activity of zebrafish larvae at 144 hpf, which might be due to the abnormal development of the spine and skeletal system. In conclusion, phthalates caused spinal birth defects in zebrafish embryos, induced transcriptional alterations of the spinal developmental genes, and led to abnormal behavior.

НАПРЯЖЕННО-ДЕФОРМИРОВАННОЕ СОСТЯНИЕ ДЕРЕВЯННЫХ ГНУТОКЛЕЕНЫХ ЭЛЕМЕНТОВ ПРИ ИЗГОТОВЛЕНИИ

Introduction: The stress-strain state (SSS) of curved laminated wooden elements may differ significantly from the SSS of straight laminated wooden elements, not only in terms of the curvature but also in terms of production specifics and operational load. A curved element is produced by bending wooden planks (lamellae) and gluing them together. In the process, the structure is subjected to initial internal stresses, as the lamellae tend to straighten out again. After production is complete, the element experiences unequal initial internal stresses, which alters its strength properties in different directions in relation to the timber fibers. At a later point, this is going to contribute to the stresses that the structure experiences under external pressure. The Russian and foreign regulations (SP, EuroCode 5, DIN) do not pay sufficient attention to this fact, which has merited this study. Methods: For the aforementioned purpose, we review a mathematical model of the SSS emergence in curved laminated wooden elements. We roughly divide the process into two stages: stage 1 involves bending separate lamellae, gluing them together, and pressing them down; stage 2 involves pressing out the laminated package. This results in prestress, which is a combination of tangential, radial, and shear stresses. Results: Our study results in a visual representation of the total prestress during stages 1 and 2. Such a representation allows for predicting stresses in curved laminated wooden structures under alternating operational loads. Discussion: We highlight the impact of the relaxation of initial stresses, which requires further study. Depending on the direction and amount of operational load, the curved laminated section of a structure may “attempt” to straighten out (i.e. with a decrease in curvature), or may curve even further. This is not properly reflected in the guidelines for wooden structures’ design and needs to be examined further.

Experimental investigations on seismic responses of RC circular column piers in curved bridges

The collapses of curved bridges are mainly caused by the damaged columns, subjected to the combined loadings of axial load, shear force, flexural moment and torsional moment, under earthquakes. However, these combined loadings have not been fully investigated. This paper firstly investigated the mechanical characteristics of the bending-torsion coupling effects, based on the seismic response spectrum analysis of 24 curved bridge models. And then 9 reinforced concrete (RC) and circular column specimens were tested, by changing the bending-tortion ratio (M/T), axial compression ratio, longitudinal reinforcement ratio and spiral reinforcement ratio, respectively. The results show that the bending-torsion coupling effects of piers are more significant, along with the decrease of girder curvature and the increase of pier height. The M/T ratio ranges from 6 to 15 for common cases, and influences the crack distribution, plastic zone and hysteretic curve of piers. And these seismic characteristics are also influenced by the compression ratio, longitudinal reinforcement ratio and spiral reinforcement ratios of piers.

Fire tests of steel tension rod systems with intumescent coating

Purpose The purpose of this paper is to investigate the performance of intumescent coating on tension rod systems and their components. Steel tension rod systems consist of tension rods, fork end connectors and associated intersection or gusset plates. In case of fire, beside the tension rods themselves, the connection parts require appropriate fire protection. Intumescent fire protection coatings prevent a rapid heating of the steel and help secure the structural load-carrying capacity. Because the connection components of tension rod systems feature surface curvature and a complex geometry, high demand is placed on the intumescence and thermal protection performance of the coatings. Design/methodology/approach In this paper, experimental studies were carried out for steel tension rod systems with intumescent coating. The examined aspects include the foaming and cracking behaviour, the influence of different dry film thicknesses, the heating rate of the steel connecting parts in comparison to the tension rods, and the mounting orientation of the tension rods together with their fork end connectors. Findings The results show that a decrease in surface curvature and/or an increase in mass concentration of the steel components leads to a lower heating rate of the steel. Moreover, the performance of the intumescent coating on tension rod systems is influenced by the mounting orientation of the steel components. Originality/value The findings based on fire tests contribute to a better understanding of the intumescent coating performance on connection components of tension rod systems. This subject has not been extensively studied yet.

Epithelium-On Versus Epithelium-Off Corneal Collagen Cross-Linking for The Management of Keratoconus

Background: Keratoconus is a noninflammatory, bilateral, frequently asymmetrical, and most common corneal ectatic disorder characterized by central corneal thinning, biomechanical weakening, and steepening of the corneal curvatures leading to substantial distortion of vision. The estimated prevalence worldwide is 54.5 cases/100,000. Objective: The aim of the work was to compare epithelium-on and epithelium-off corneal collagen cross-linking for the management of keratoconus as regards keratoconus progression and visual outcome. Patients and methods: In this study, 20 eyes of 11 keratoconus patient were included. All were having keratoconus and presented with diminution of vision, increasing myopia and / or astigmatism. Cases with corneal scarring, corneal thickness less than 400 μm at the thinnest point and active corneal infections were excluded. The preoperative evaluation of patients showed UCVA, In epithelium-on (group 1) ranging from 0.05 to 0.60 with a mean 0.29 ± 0.21 and in epithelium-off (group 2) UCVA ranging from 0.05 to 0.50 with a mean 0.23 ± 0.13. Results: The postoperative results revealed improvement of UCDVA and BSCVA at 6 month postoperative in both groups. The postoperative manifest refraction spherical equivalent showed stability with mild improvement in both groups. Keratometric readings showed a decrease in curvature in both groups in the follow up period. Corneal hysteresis (CH) and corneal resistance factor (CRF) showed no significant difference after 6 months of follow up. Conclusion: It could be concluded that UVA/Riboflavin cross-linking of ectatic cornea by its two techniques is effective, safe, stable and do not affect corneal biomechanical characteristics, that leads in the majority of the cases to a halt the progression of ectasia.

Effects of Template and Molecular Nanostructure on the Performance of Organic–Inorganic Photomechanical Actuator Membranes

AbstractPorous anodic aluminum oxide (AAO) membranes template the growth of photochromic crystalline nanowires. The resulting organic–inorganic composite can function as a photomechanical bending actuator. In order to investigate how the nanostructural properties of both the organic and inorganic components affect the photomechanical response, the composite mechanical properties are characterized using a variety of methods. There is a significant variation in both morphology and elastic modulus for two commercially available AAO templates with nominally identical pore diameters of 200 nm. After these templates are filled with diarylethene molecules that undergo a ring‐open to ring‐closed photoisomerization, the light‐generated curvature and mechanical work are evaluated using two different methods. The templates with a lower average elastic modulus (16 GPa vs 68 GPa) generate almost an order of magnitude more photomechanical work. The dependence of the photomechanical response on the chemical structure of the photochrome is assessed by comparing the performance of a diarylethene that undergoes a crystal expansion to that of one that undergoes a contraction, which leads to a decrease in curvature. Both the inorganic template and the organic active component play important roles in the overall photomechanical response, with substantial room to improve the performance.

Influence of Cholesterol and Bilayer Curvature on the Interaction of PPO-PEO Block Copolymers with Liposomes.

Interactions of nonionic poly(ethylene oxide)- b-poly(propylene oxide) (PEO-PPO) block copolymers, known as Pluronics or poloxamers, with cell membranes have been widely studied for a host of biomedical applications. Herein, we report how cholesterol within phosphatidylcholine (POPC) lipid bilayer liposomes and bilayer curvature affects the binding of several PPO-PEO-PPO triblocks with varying PPO content and a tPPO-PEO diblock, where t refers to a tert-butyl end group. Pulsed-field-gradient NMR was employed to quantify the extent of copolymer associated with liposomes prepared with cholesterol concentrations ranging from 0 to 30 mol % relative to the total content of POPC and cholesterol and vesicle extrusion radii of 25, 50, or 100 nm. The fraction of polymer bound to the liposomes was extracted from NMR data on the basis of the very different mobilities of the bound and free polymers in aqueous solution. Cholesterol concentration was manipulated by varying the molar percentage of this sterol in the POPC bilayer preparation. The membrane curvature was varied by adjusting the liposome size through a conventional pore extrusion technique. Although the PPO content significantly influences the overall amount of block copolymer adsorbed to the liposome, we found that polymer binding decreases with increasing cholesterol concentration in a universal fashion, with the fraction of bound polymer dropping 10-fold between 0 and 30 mol % cholesterol relative to the total content of POPC and cholesterol. Increasing the bilayer curvature (decreasing the radius of the liposome) in the absence of cholesterol increases polymer binding between 2- and 4-fold over the range of liposome sizes studied. These results demonstrate that cholesterol plays a dominant role, and bilayer curvature has a less significant impact as the curvature decreases, on polymer-membrane association.

Management of Peyronie's disease with collagenase Clostridium histolyticum in the acute phase.

Peyronie's disease (PD) can affect men of all ages and is associated with penile pain as well as curvature and erectile dysfunction. Treatment modalities for PD include conservative, less invasive and surgical treatments. Choice of treatment depends on the disease's phase. Injection of collagenase Clostridium histolyticum (CCH) is only the Food and Drug Administration approved treatment for the management of the chronic phase of the disease. Only a few limited studies have evaluated its potential benefits during the acute phase. To evaluate the current evidence on the use of injectable CCH during the acute or active phase of PD. We performed a PubMed database search for articles published between 2015 and 2018 that investigated the use of CCH for the management of the acute phase of PD. Search keywords included "Peyronie's disease", "collagenase Clostridium histolyticum", and "acute phase". Changes in penile curvature after treatment with injectable CCH. Mean curvature decrease ranged between 15.8° and 22.6° corresponding to 27.4-37.4% decrease from baseline after 2.5-4 cycles, corresponding to 5-8 injections, of CCH treatment in patients during the acute phase of PD. Intralesional CCH injection therapy during the acute phase of PD can be both safe and effective and clinically significant improvements in penile curvature may be achieved. Larger multi-institutional studies are, however, still needed to confirm these results and validate this additional indication for CCH.

Studies of spin transport in fullerene films

The fullerene C60, C70, and C84 molecules, that are composed of ∼99% naturally abundant 12C having spinless nuclei, are considered to have miniature hyperfine interaction and also weak intrinsic spin-orbit coupling (SOC) due to the light carbon atoms. However, it has been theoretically predicted that the curvature of the fullerene molecules may increase the SOC due to the induced hybridization of the π and σ electrons on the carbon atoms that reside on the fullerene molecule surface. In this work, we have measured the spin diffusion length in films of C60, C70, and C84 in NiFe/fullerene/Pt trilayer devices, where pure spin current is injected into the fullerene film at the NiFe/fullerene interface via spin pumping induced by microwave absorption at ferromagnet resonance conditions, and subsequently detected at the fullerene/Pt interface as electrical current via the inverse spin-Hall effect. The obtained spin diffusion lengths in the fullerene films are of the order of 10 nm and increase from C60 to C84 in which the fullerene molecule’s curvature decreases; this finding validates the existence of curvature-induced SOC in the fullerenes. Our results deepen the understanding of spin transport in fullerene films and may benefit the design of molecular spintronic devices.

Compressible unsteady Görtler vortices subject to free-stream vortical disturbances

The perturbations triggered by free-stream vortical disturbances in compressible boundary layers developing over concave walls are studied numerically and through asymptotic methods. We employ an asymptotic framework based on the limit of high Görtler number, the scaled parameter defining the centrifugal effects; we use an eigenvalue formulation where the free-stream forcing is neglected; and we solve the receptivity problem by integrating the compressible boundary-region equations complemented by appropriate initial and boundary conditions that synthesize the influence of the free-stream vortical flow. Near the leading edge, the boundary-layer perturbations develop as thermal Klebanoff modes and, when centrifugal effects become influential, these modes turn into thermal Görtler vortices, i.e. streamwise rolls characterized by intense velocity and temperature perturbations. The high-Görtler-number asymptotic analysis reveals the condition for which the Görtler vortices start to grow. The Mach number is destabilizing when the spanwise diffusion is negligible and stabilizing when the boundary-layer thickness is comparable with the spanwise wavelength of the vortices. When the Görtler number is large, the theoretical analysis also shows that the vortices move towards the wall as the Mach number increases. These results are confirmed by the receptivity analysis, which additionally clarifies that the temperature perturbations respond to this reversed behaviour further downstream than the velocity perturbations. A matched-asymptotic composite profile, found by combining the inviscid core solution and the near-wall viscous solution, agrees well with the receptivity profile sufficiently downstream and at high Görtler number. The Görtler vortices tend to move towards the boundary-layer core when the flow is more stable, i.e. as the frequency or the Mach number increase, or when the curvature decreases. As a consequence, a region of unperturbed flow is generated near the wall. We also find that the streamwise length scale of the boundary-layer perturbations is always smaller than the free-stream streamwise wavelength. During the initial development of the vortices, only the receptivity calculations are accurate. At streamwise locations where the free-stream disturbances have fully decayed, the growth rate and wavelength are computed with sufficient accuracy by the eigenvalue analysis, although the correct amplitude and evolution of the Görtler vortices can only be determined by the receptivity calculations. It is further proved that the eigenvalue predictions of the growth rate and wavenumber worsen as the Mach number increases as these quantities show a dependence on the wall-normal direction. We conclude by qualitatively comparing our results with the direct numerical simulations available in the literature.

Physical Plasma Membrane Perturbation Using Subcellular Optogenetics Drives Integrin-Activated Cell Migration.

Cells experience physical deformations to the plasma membrane that can modulate cell behaviors like migration. Understanding the molecular basis for how physical cues affect dynamic cellular responses requires new approaches that can physically perturb the plasma membrane with rapid, reversible, subcellular control. Here we present an optogenetic approach based on light-inducible dimerization that alters plasma membrane properties by recruiting cytosolic proteins at high concentrations to a target site. Surprisingly, this polarized accumulation of proteins in a cell induces directional amoeboid migration in the opposite direction. Consistent with known effects of constraining high concentrations of proteins to a membrane in vitro, there is localized curvature and tension decrease in the plasma membrane. Integrin activity, sensitive to mechanical forces, is activated in this region. Localized mechanical activation of integrin with optogenetics allowed simultaneous imaging of the molecular and cellular response, helping uncover a positive feedback loop comprising SFK- and ERK-dependent RhoA activation, actomyosin contractility, rearward membrane flow, and membrane tension decrease underlying this mode of cell migration.

Process Intensification by Using a Helical Capillary Microreactor for a Continuous Flow Synthesis of Peroxypropionic Acid and Its Kinetic Study

Peroxypropionic acid (PPA) is an important organic chemical compound. Due to its versatile oxidizing properties, it is used in the oil, chemical and other industries. In this article, an attempt was made for the production of PPA in a Teflon helical capillary microreactor without and with homogeneous catalyst. The article reports the perhydrolysis of PPA with the effect of various parameters such as concentration of hydrogen peroxide, molar ratio of reactants, radius of curvature of the microreactor, concentration of catalyst and temperature. The reaction is slow, as the PPA equilibrium was found to be reached within 10 min at a temperature of 50 °C and at 10 mol % catalyst loading based on propionic acid. The reaction was carried out in 13.25 and 23.25 mm radius of curvature of the microreactor in which 4.0375 and 3.488 mol/L concentrations of PPA respectively were obtained at 50 ºC and 10 mol % catalyst. It indicates that as radius of curvature decreases, better mixing was provided among the reactants for the reaction to give enhanced yield and selectivity. From the experimental data and the kinetic expressions, the expressions of activation energies and reaction rate constants were determined. For PPA synthesis and hydrolysis, the activation energies were 43.897 and 20.658 kJ/mol respectively without catalyst, while the activation energies for both the cases were 42.314 and 17.514 kJ/mol respectively with catalyst of 10 mol% based on propionic acid. The dean number, curve tube friction factor and pressure drop also determined for the helical capillary microreactor.

Backreaction of superhorizon scalar field fluctuations on a de Sitter geometry: A renormalization group perspective

We study the backreaction of gravitationally amplified quantum fluctuations of scalar fields on a classical de Sitter geometry. We formulate the problem in the framework of the Wilsonian renormalisation group, which allows us to treat the scalar field fluctuations in a nonperturbative manner and to follow the renormalisation flow of the spacetime curvature as long wavelength, superhorizon fluctuations are progressively integrated out. For light fields in units of the spacetime curvature, these are described by an effective zero-dimensional field theory and can essentially be computed analytically. A nontrivial flow of the spacetime curvature is induced either by a nonminimal coupling to gravity or by self-interactions. The latter leads to a decrease of the spacetime curvature through loop effects, which, for minimally coupled, massless fields, grow unbounded in the infrared. However, such large loop contributions are eventually screened by the dynamical generation of a nonperturbative, gravitationally induced mass and the renormalisation of the spacetime curvature saturates to a nonzero value. Finally, we show that, in the case of spontaneously broken continuous symmetries, the Goldstone modes do not contribute to the infrared flow of the spacetime curvature, despite being strongly amplified by the gravitational field.

Fatiguing stimulation increases curvature of the force-velocity relationship in isolated fast-twitch and slow-twitch rat muscles.

In skeletal muscles, the ability to generate power is reduced during fatigue. In isolated muscles, maximal power can be calculated from the force-velocity relationship. This relationship is well described by the Hill equation, which contains three parameters: (1) maximal isometric force, (2) maximum contraction velocity and (3) curvature. Here, we investigated the hypothesis that a fatigue-induced loss of power is associated with changes in curvature of the force-velocity curve in slow-twitch muscles but not in fast-twitch muscles during the development of fatigue. Isolated rat soleus (slow-twitch) and extensor digitorum longus (EDL; fast-twitch) muscles were incubated in Krebs-Ringer solution at 30°C and stimulated electrically at 60 Hz (soleus) and 150 Hz (EDL) to perform a series of concentric contractions to fatigue. Force-velocity data were fitted to the Hill equation, and curvature was determined as the ratio of the curve parameters a/F0 (inversely related to curvature). At the end of the fatiguing protocol, maximal power decreased by 58±5% in the soleus and 69±4% in the EDL compared with initial values in non-fatigued muscles. At the end of the fatiguing sequence, curvature increased as judged from the decrease in a/F0 by 81±20% in the soleus and by 31±12% in the EDL. However, during the initial phases of fatiguing stimulation, we observed a small decrease in curvature in the EDL, but not in the soleus, which may be a result of post-activation potentiation. In conclusion, fatigue-induced loss of power is strongly associated with an increased curvature of the force-velocity relationship, particularly in slow-twitch muscles.

Spin—Orbit Coupling in Single-Walled Gold Nanotubes

The effect of spin—orbit coupling on the electron levels of (5, 3), (8, 7), (11, 3), (18, 11), (10, 5), (8, 8), and (13, 0) gold nanotubes of various diameters and chirality was studied in the framework of the relativistic version of the linear augmented cylindrical wave method. Spin-dependent band structures and electron state densities were calculated. Spin—orbit coupling is manifested as splitting of nonrelativistic dispersion curves. For the dispersion curve that crosses the Fermi level in the (5, 3) tube of the minimum radius, this splitting reaches 0.5 eV and decreases on going to low-lying valence band states. An increase in the radius and a decrease in the cylindrical surface curvature of these nanotubes suppress the spin—orbit splitting. All tubes possess a metal type band structure in which the number of conduction channels increases with increasing radius of the nanotube.

Hydrodynamics maneuver of a single helical flagellum swimming robot at low-Reynolds condition

Helical swimming robots with a capable propulsion system at low-Reynolds numbers have been proposed for many applications. Although linear propulsion characteristics of swimming robots with a single helical flagellum have been extensively studied, the characteristics of maneuverability have not been completely investigated yet. This study presents a new method for the maneuverability of the helical swimming robot with a single helical flagellum. This mechanism is based on the change in the angle between the helical and body axes. This study shows that a change in the aforementioned angle can enable the swimming robot to have turning maneuvers in clockwise or counterclockwise directions. Moreover, the swimming robot will move in a straight line if the helical and body axes are parallel. To investigate this new method and predict the robot’s behavior at various inclination angles, a hydrodynamics model is used. To validate the hydrodynamics model, an experimental prototype of a macro-size swimming robot with specific inclination angles is fabricated. The results indicate that the helical swimming robot swims on circular trajectories through specific inclination angles between the helical flagellum and the body axis. Moreover, the radius of curvature decreases by increasing the inclination angle. Results of the validated hydrodynamics model indicate that the turning velocity has approximately a constant value at different inclination angles depending on the rotational frequency and geometrical parameters of the swimming robot. Finally, the effects of geometrical parameters of the body and the helical flagellum on the radius of curvature and turning velocity are investigated through the proposed hydrodynamics model. The verified results indicate that the hydrodynamics model provides a viable alternative model to predict the behavior of a helical swimming robot at various inclination angles within a range of design variables. This new method can be introduced as a mechanism for maneuverability of the helical swimming robots with a single helical flagellum and will be able to control the parameters in this type of swimmers for the implementation of predefined missions.

Current Intensity Trends in the Labrador and Irminger Seas Based on Satellite Altimetry Data

Sea level measurements from an absolute dynamic typography dataset for the period of 1993–2015 were used to study the variability in geostrophic circulation in the Labrador and Irminger seas. Analysis of current intensity trends calculated by geostrophic formulas has shown a weakening in cyclonic circulation observed in these two convection centers. The intensity trends are negative in all the main currents making up the Subpolar Gyre: the Labrador, East Greenland, West Greenland, and Irminger currents. On average, the negative intensity trends in the indicated currents are –0.3 cm s–1 yr–1, in individual areas reaching –0.5 cm s–1 yr–1, which corresponds to a decrease in current speed of 6.9–11.5 cm/s for the 23-year interval. Weakening of cyclonic circulation is likely predetermined by weakening convection processes and a decrease in the dome-shaped curvature of isopycnal surfaces generated by upwelling of weakly stratified water closer to the surface. This is confirmed by analysis of satellite data: in periods when deep convection weakens, the intensity of cyclonic circulation decreases at the margin of the Labrador and Irminger seas. Simultaneously with weakening currents, an increase in intensity is observed from the outer (with respect to the convection centers) margin of the considered currents, including in coastal zones.

Membrane curvature affects the stability and folding kinetics of bacteriorhodopsin

Biological membrane is crucial for the function, stability and folding of membrane proteins. By studying the stability and folding kinetics of bacteriorhodopsin (bR) in lipid vesicles with different sizes, here we report the influence of membrane curvature (vesicle size) on the stability and folding kinetics of bR. The results show that both the stability and folding kinetics of bR can be significantly changed when reconstituted into mimic membranes with different curvatures. The stability of bR decreases and unfolding rate of bR increases with the growth of vesicle size, i.e. decrease of membrane curvature. Our results suggest that it is possible to regulate the properties of membrane proteins by changing the curvature of membranes.

Detection of Actin Filament and Cofilin Interaction Change by Actin Filament Curvature Decreasing.

Actin filament senses mechanical forces and it is transduced into biochemical signals during many cellular processes. In the disassembling process of actin filaments, cofilin plays a central role as the actin filament depolymerization. In this study, we evaluated a quantitative analysis of the actin filament-cofilin interaction change dependent upon the actin filament curvature decrease using atomic force microscopy (AFM) and a fabricated wave-like substrate. A wave-like substrate was fabricated by a maskless photo-lithography of a spin coated film on a glass substrate, and graphene oxide sheet was used for the decreasing of non-specific interaction between protein and the substrate. By single-molecule force spectroscopy, we determined rupture force of actin filament-cofilin binding on the wave-like substrate and a flat substrate. The rupture force of actin filament-cofilin binding at the curvature of -1.35 μm-1 showed a value approximately 4 times higher than the rupture force at the curvature of -0.15 μm-1. The present study will provide the possibility and quantitative evidence that mechanical stress on cytoskeletal filaments can modulate how they interact with their binding proteins.