Contract Zone Research Articles

Multi‐Zone Visco‐Node‐Pore Sensing: A Microfluidic Platform for Multi‐Frequency Viscoelastic Phenotyping of Single Cells

AbstractThis study introduces multi‐zone visco‐Node‐Pore Sensing (mz‐visco‐NPS), an electronic‐based microfluidic platform for single‐cell viscoelastic phenotyping. mz‐visco‐NPS implements a series of sinusoidal‐shaped contraction zones that periodically deform a cell at specific strain frequencies, leading to changes in resistance across the zones that correspond to the cell's frequency‐dependent elastic G′ and viscous G″ moduli. mz‐visco‐NPS is validated by measuring the viscoelastic changes of MCF‐7 cells when their cytoskeleton is disrupted. mz‐visco‐NPS is also employed to measure the viscoelastic properties of human mammary epithelial cells across the entire continuum of epithelial transformation states, from average‐ and high‐risk primary epithelial cells, to immortal non‐malignant (MCF‐10A), malignant (MCF‐7), and metastatic (MDA‐MB‐231) cell lines. With a throughput of 600 cells per hour and demonstrated ease‐of‐use, mz‐visco‐NPS reveals a remarkable level of single‐cell heterogeneity that would otherwise be masked by ensemble averaging.

Pre-commitment in bargaining with endogenous credibility

We study whether negotiators adopt commitment tactics in bargaining, a concept first proposed by Schelling (1956), and their choice of the credibility of commitment. In a modified ultimatum game experiment, the responder is allowed to pre-commit to a minimum acceptable offer (MAO) before an offer is proposed. Meanwhile, they choose the credibility of the commitment, measured by a cost of backing down (CBD) incurred if the responder accepts an offer lower than the MAO. We find that nearly 40% of responders chose a CBD substantially lower than their MAO, despite the fact that proposers were more likely to cave in and offer a larger share of the bargaining surplus when fully credible commitments were made. Informing responders of the proposers' minimum acceptable share of the bargaining surplus does not reduce partially credible commitments, suggesting that these commitments were unlikely made to enlarge the contract zone. Further treatments and analyses suggest that other-regarding preferences may be the reason behind partially credible commitments.

Two-dimensional strain rate imaging study using a polarization camera and birefringent aqueous cellulose nanocrystal suspensions

The birefringence response of aqueous cellulose nanocrystal (CNC) suspensions in a two-dimensional laminar flow is measured and studied. The suspensions have CNC concentrations of 1.0 wt% (weight percentage) and 1.2 wt%. Cellulose nanocrystals are optically anisotropic rod-like particles that align when subjected to local velocity gradients, whereas at rest, they remain randomly orientated by Brownian motion. The alignment causes birefringence, a phenomenon also known as flow-induced birefringence. We study the flow through an additively manufactured flow channel and measure the amount of birefringence as well as the position of the refractive index axes by using polarizers and a polarization camera. With the help of reference data published in a previous study (Lane, Rode, et al., 2022a), strain rates are derived from the birefringence measurements and compared with numerical simulations. Two flow situations are studied, a plane Poiseuille flow and the flow around a cosine-shaped constriction. The experimentally derived shear rates for the plane Poiseuille flow are consistent with theoretical and computational results. The derived strain rates for the flow around the cosine-shaped constriction show an unexpected asymmetric profile, with the strain rates in the contraction zone being larger than in the expansion zone. The averaged orientation of the CNCs in the flow is linked to the position of the refractive index axes. In the contraction zone, the CNCs tend to align parallel to the flow, whereas in the expansion zone, the CNCs tend to align perpendicular to the flow. The results of this study are discussed in the context of previous, similar studies. The asymmetric strain rate profile around the cosine-shaped constriction is thought to originate from history effects, and the alignment of the CNCs is influenced by extensional rates.

Experimental study on the deformation of sandy soil around multi-helical anchor piles under horizontal load

The deformation characteristics of sandy soil around multi-helical anchor piles have an important influence on their bearing capacity under horizontal loading. To explore the interaction mechanism between anchor pile and soil, this study combines a model test system with particle imaging velocimetry to study the deformation and bearing characteristics of the soil around multi-helical anchor piles under horizontal loading. The results show the following. (1) The sand density and anchor sheet buried depth have a significant effect on the range of the influence of the soil displacement around the helical anchor pile, and on the distribution of the active and passive zones. (2) With increasing density, the influence area of the active zone rearward of the pile decreases, whereas the opposite is true for the passive zone in front of the pile. Under shallow buried conditions, the area of influence of the passive zone rearward of the pile extends to the sand surface; whereas under deep buried conditions, the area of influence of the transition zone decreases. (3) The buried depth is the main factor in the formation of the transition zone and the rotating damage zone. As the buried depth increases, the angle between the shear failure surface of the passive zone rearward of the pile and the vertical direction gradually decreases; the development direction of the shear failure surface of the disturbance zone in front of the pile is lower right-vertical downward-lower left. (4) The volume expansion zone on the left side of the helical anchor pile gradually transitions from extending to the surface of the sand to the lower left side of the bottom anchor. Regardless of the buried depth, the maximum value of the volume strain in the soil always occurs in the upper part of the top anchor, and the soil between the two anchor plates is always in the volume contraction zone.

Spatial variation of mean flow and turbulence characteristics within channel contraction – an experimental approach

ABSTRACT The influence of three different channel contractions on the mean flow and turbulent characteristics has been measured experimentally in a recirculating flume. The velocity deficit, turbulence intensity, Reynolds stress, and turbulence scales data within the channel contractions were obtained from three-dimensional velocity fluctuations measurements using Acoustic Doppler Velocimeter. The mean flow profile shows undulation towards the free surface for all the contraction ratios, indicating the presence of the velocity-dip phenomenon due to the secondary currents. These currents changed the pattern of turbulence intensities and Reynolds shear stresses significantly within the channel contraction compared to the without contraction case. The results reveal that with the increase of channel contraction ratio, the strength of the secondary current increased considerably and resulted in a significant change in flow patterns close to the free surface compared to the bottom. The length scales of turbulent flow indicate eddy sizes in different ranges to be smaller at near-bed region within the contraction zone due to the breakdown of larger eddies.

Mesoscale analysis of dry shrinkage fractures in concrete repair systems using FEM and VEM

ABSTRACT A novel numerical method that used a FEM coupled with a virtual element method was proposed to evaluate the drying shrinkage of concrete repair systems. The stress distribution, crack development of the concrete repair systems due to drying shrinkage were investigated using this method. (1) The mortar along the tangent direction of the aggregate boundary was subjected to the aggregate constraint, allowing shrinkage cracks to form easily. The overlay first developed a significant number of microcracks on surface, followed by debonding at both ends of the interface. (2) Owing to the confinement of the aggregate below the surface, the surface tensile stress of the overlay had a ‘hump’ distribution. After cracking, the surface was divided into several contraction zones, with tensile and compressive stresses applied to the boundary and interior of the contraction zone, respectively. (3) As the interface de-bonded, the tensile and shear stresses of the interface began to increase from both sides and moved inward. The rise in local compressive and shear stresses were induced by the constraint of the aggregate in the bonding interfacial region. (4) Tensile stress caused the first damage, and the shear stress caused interface debonding to evolve.

Blood flow CFD simulation on a cerebral artery of a stroke patient

The purpose of this paper is to conduct a numerical simulation of the stroke patient's cerebral arteries and investigate the flow parameters due to the presence of stenosis. The computational fluid dynamics (CFD) simulations are based on simplified and realistic cerebral artery models. The seven simplified models (benchmarks) include straight cylindrical vessels with idealized stenosis with variable d/D (0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1). The realistic model of the cerebral artery is based on magnetic resonance imaging (MRI) for patient-specific cerebral arteries. The simulation for the realistic model of the cerebral artery is performed at boundary conditions measured by ultrasonography of the input and the output flow profiles (velocity and pressure). The obtained CFD results of the benchmarks are validated with actual data from the literature. Furthermore, a previous vascular contraction is assumed to be exist and the effect of this contraction area ratio on the blood flow regime is discussed and highlighted. Furthermore, CFD results show that a certain vascular contraction area critically affects the blood flow which shows increasing the wall shear stress WSS at the stenosis site. An increase in the blood velocity and vortex appears after the contraction zone, this lead to vessel occlusion and strokes.Article highlightsThe pressure drop across the arterial contraction is reduced when the area ratio d/D is increased.In some cases, the vortex can prevent blood flow from crossing, this leads to vessel occlusion especially at low d/DThe WSS near the contraction area is high. Increasing the WSS can cause embolism that leads to lead to vessel occlusion.

The effect of a larger contract zone on agreement rates under arbitration

In the arbitration literature there is no common agreement about the nature of the relationship between the size of the contract zone and agreement rates. The results from our experiment show that, when the size of the contract zone increases there are two prevailing effects: one effect is attributed to changes in the range of possible outcomes, and the other to coordination issues. While more room for negotiation leads to higher agreement rates, coordination problems largely impede agreement among rational subjects. The overall effect of an increase in the contract zone depends on the relative magnitude of these opposing effects.

Temperature evolution and freeze–thaw characteristics of water-saturated-dried coal samples during low-temperature freeze–thaw process

In order to study the frost heaving deformation characteristics of coal under the action of liquid nitrogen (LN2), this paper takes bituminite under saturated and dry conditions as the research object. The temperature-strain monitoring test was used to explore the evolution law of coal body strain during LN2 freezing and thawing. NMR was used to study the effect of free water space on pore structure. Uniaxial compressive strength was also used to evaluate mechanical properties. The results show that the temperature drop rate of the saturated coal sample is higher than that of the dry sample during the freezing process. During the thawing process, the time required for the core temperature of the dry coal sample to reach equilibrium is shorter. Based on the volume deformation of coal samples during the freezing and thawing process of LN2, the coal samples were divided into eight stages: freezing contraction zone I-freezing expansion zone II-freezing contraction zone III-equilibrium zone IV-thawing expansion zone V-thawing contraction zone VI-thawing expansion zone VII-equilibrium VIII zone. The thermal expansion coefficient κ is defined to analyze the relationship between the volume strain and the core temperature of the saturated and dry coal samples, and it is found that the saturated coal samples have stronger sensitivity to temperature during the freezing and thawing process. After the freezing and thawing of LN2, the internal pore damage of saturated coal sample is more serious. In addition, the uniaxial compressive strength of saturated and dry coal samples decreased, and the deterioration degree of saturated coal sample was greater than that of dry coal sample.

Geodetic and Geological Deformation of the Island Arc in Northeast Japan Revealed by the 2011 Tohoku Earthquake

Northeast Japan is a typical island arc related to the Pacific plate subduction. The 2011 Mw9.0 Tohoku-oki earthquake provided a unique opportunity to analyze crustal deformation with different boundary conditions, similar to a gigantic rock deformation experiment. We review findings obtained through various observations and data analyses in Northeast Japan, focusing on the crustal deformation in different timescales. The occurrence of the M9 earthquake solved the ongoing paradox that the geodetic strain rate is an order of magnitude larger than the geologic estimate, showing that the centennial geodetic observation had mainly captured the elastic strain accumulation. Along the localized contraction zone along the Japan Sea coast, a comparison of postseismic and interseismic deformation patterns revealed a significant contribution of inelastic deformation, which plays an essential role in long-term deformation. Along the Pacific coast, rapid interseismic subsidence and unexpected coseismic subsidence were followed by a rapid postseismic uplift, indicating that viscous relaxation in the mantle is of essential importance. These findings advance our understanding of plate interactions and the tectonic evolution of the island arc. ▪ The 2011 Tohoku-oki earthquake provided the most complete crustal deformation data set ever for interseismic, coseismic, and postseismic periods. ▪ The discrepancy between the geologic and geodetic deformation rates in Northeast Japan is attributed to an elastic strain due to interplate locking. ▪ A significant contribution of inelastic deformation in the island arc crust is identified through a comparison of interseismic and postseismic deformations.

Emergence of a geometric pattern of cell fates from tissue-scale mechanics in the Drosophila eye.

Pattern formation of biological structures involves the arrangement of different types of cells in an ordered spatial configuration. In this study, we investigate the mechanism of patterning the Drosophila eye epithelium into a precise triangular grid of photoreceptor clusters called ommatidia. Previous studies had led to a long-standing biochemical model whereby a reaction-diffusion process is templated by recently formed ommatidia to propagate a molecular prepattern across the eye. Here, we find that the templating mechanism is instead, mechanochemical in origin; newly born columns of differentiating ommatidia serve as a template to spatially pattern flows that move epithelial cells into position to form each new column of ommatidia. Cell flow is generated by a source and sink, corresponding to narrow zones of cell dilation and contraction respectively, that straddle the growing wavefront of ommatidia. The newly formed lattice grid of ommatidia cells are immobile, deflecting, and focusing the flow of other cells. Thus, the self-organization of a regular pattern of cell fates in an epithelium is mechanically driven.

The Role of Along‐Fault Dilatancy in Fault Slip Behavior

AbstractEarthquakes result from fast slip that occurs along a fault surface. Interestingly, numerous dense geodetic observations over the last two decades indicate that such dynamic slip may start by a gradual unlocking of the fault surface and related progressive slip acceleration. This first slow stage is of great interest, because it could define an early indicator of a devastating earthquake. However, not all slow slip turns into fast slip, and sometimes it may simply stop. In this study, we use a numerical model based on the discrete element method to simulate crustal strike‐slip faults of 50 km length that generate a wide variety of slip‐modes, from stable‐slip, to slow earthquakes, to fast earthquakes, all of which show similar characteristics to natural cases. The main goal of this work is to understand the conditions that allow slow events to turn into earthquakes, in contrast to those that cause slow earthquakes to stop. Our results suggest that fault surface geometry and related dilation/contraction patterns along strike play a key role. Slow earthquakes that initiate in large dilated regions bounded by neutral or low contracted domains, might turn into earthquakes. Slow events occurring in regions dominated by closely spaced, alternating, small magnitude dilational and contractional zones tend not to accelerate and may simply stop as isolated slow earthquakes.

Energy and momentum correction coefficients within contraction zone in open-channel combining flows

Flow dynamics associated with open-channel confluences are highly three-dimensional (3D) with significant velocity gradients in the contraction zone downstream of junctions. The main objective of the present study was to investigate the impact of discharge ratio and junction angle on the non-uniformity of the velocity distribution within the contraction zone. A one-dimensional (1D) theoretical model and a 3D numerical model were developed to establish the relationships of the maximum values of energy and momentum correction coefficients (αm and βm) with discharge ratio (q) and junction angle (θ). The expressions of αm and βm were determined in terms of q and cosθ with the 1D theoretical model, and the constants were determined through regression analysis with the computed results from the 3D numerical model. The expressions show that αm and βm increased with an increase in junction angle or a decrease in discharge ratio due to the improved three-dimensionality of the flow structure. The expressions of αm and βm determined from the present study are consistent with the existing findings with θ = 90°.

Non-Uniform Circumferential Expansion of Cylindrical Li-Ion Cells—The Potato Effect

This paper presents the non-uniform change in cell thickness of cylindrical Lithium (Li)-ion cells due to the change of State of Charge (SoC). Using optical measurement methods, with the aid of a laser light band micrometer, the expansion and contraction are determined over a complete charge and discharge cycle. The cell is rotated around its own axis by an angle of α=10° in each step, so that the different positions can be compared with each other over the circumference. The experimental data show that, contrary to the assumption based on the physical properties of electrode growth due to lithium intercalation in the graphite, the cell does not expand uniformly. Depending on the position and orientation of the cell coil, there are different zones of expansion and contraction. In order to confirm the non-uniform expansion around the circumference of the cell in 3D, X-ray computed tomography (CT) scans of the cells are performed at low and at high SoC. Comparison of the high resolution 3D reconstructed volumes clearly visualizes a sinusoidal pattern for non-uniform expansion. From the 3D volume, it can be confirmed that the thickness variation does not vary significantly over the height of the battery cell due to the observed mechanisms. However, a slight decrease in the volume change towards the poles of the battery cells due to the higher stiffness can be monitored.

A Double-Envelope Mitral Inflow Spectral Doppler Profile After MitraClip

A Double-Envelope Mitral Inflow Spectral Doppler Profile After MitraClip

Mapping soil arching-induced shear and volumetric strains in dense sands

Arching is regarded as a ubiquitous phenomenon in geomaterials where a new stress field is created following partial, induced displacements in the geomaterial. In the past, less attention has been paid to the deformations associated with the arching effect. The Digital Image Correlation (DIC) technique was implemented to map the shear and volumetric strain fields where arching occurred in a dense sand layer placed in a trapdoor apparatus. Model tests were conducted under active and passive arching along with surcharge loading. It was observed that shear bands comprising of two sections with different orientation angles were formed. The orientation angles of the shear bands were associated with the dilation angle of the sand (the deformation related angle of the soil) rather than its internal angle of friction (the stress related angle of the soil). The magnitude of shear strains increased with trapdoor displacement. It was also found that strain localization was associated with dilation. Contraction zones were also detected in the sand layer specifically at the surface and on the trapdoor element. In addition, it was realized the shear bands developed in the passive arching condition possessed greater width and inclination angles compared to bands of the active arching situation. The local surcharge used in the experiments markedly affected the strain localization and volumetric strain patterns and magnitudes.

Using seismic and well data to determine processes of folding in the Pomeranian segment of the Caledonian Foredeep Basin, Poland

Recognition of fractures and faults related to different types of folding is important for understanding how fluids flow in folds or which parts of folds represent a better productive sector of reservoirs due to, for example, changes in the intensity and distribution of fractures.In this paper, we suggest that seismic data alone may be insufficient to determine the style of buckle folding. The differences in mechanical properties of the rock masses favour the development of two main types of internal deformation within the buckle folds, that originated as a result of layer-parallel shortening: flexural slip/flow folding and neutral-surface folding. However, it is difficult to tell from seismic data alone which type of deformation had occurred.This paper presents the advantages of analyzing structures in core combined with results of amplitude variation with azimuth (AVAZ) analysis applied on the 3D seismic survey, when compared to the use of seismic data alone. To illustrate this, we use examples of seismic-scale folds, interpreted as buckle folds formed within the Pomeranian segment of the Caledonian Foredeep Basin.The analysis of structures related to the amplification of one fold known as the Opalino Anticline leads us to conclude, that this approach allowed us to recognize that folding within the mostly homogenous, isotropic Ordovician and Silurian mudstone formations is associated with bed-parallel and bed-perpendicular veins, reverse faults, thrusts, stylolites and normal faults, which formed at different depths within the fold. We consider the structures to have developed as a result of buckling of the mudstone formations and demonstrate that the process facilitated neutral-surface folding, which caused outer-arc extension in the higher parts of the Opalino Anticline and the development of an inner-arc contraction zone in the lower parts of the anticline. We show that this approach helps to predict the distribution of structures related with folding, which in turn aids in estimating the reservoir quality.

Field target dimensions of flow constrained by a transverse dam

Construction and operation of channel control structures in valley rivers require carrying out a comparative study of their operation during design operational periods. The goal of this work is to set target dimensions for flow deformed by the transverse blind dam in field conditions, on the dam № 30 in Amudarya river: the length of upstream and downstream vortex zones, boundaries between the core and intensive turbulent mixing zones, vortex zone boundaries, and their comparison with experimental data. Locations of the sections are set based on the possibility to accomplish the goal, in the headrace, where flow natural condition is maintained, in contraction zone, and within the borders of downstream vortex zone. Sections were fixed with landmarks and leveling instrument Vegal 24 was installed there. Zone boundaries and vortex lengths were set with the use of floats directly from the riverside of the use of boats. Design relationships obtained from the results of laboratory experiments were used to determine the length of upstream vortex zone, contraction area, downstream vortex zone, boundaries of hydraulically homogeneous zones, which were then compared with the field data. It was also set, that coefficients characterized flow spreading beyond the contracted section were equal to C 2 =0.186 and C 3 =0.545 as compared to 0.11 and 0.16 in the theory of turbulent jets. The length of vortex zones is shorter by 11.9% to 26.8%, which shows how much the distance between dams must be decreased in the system.

Mobile flume for inverted semicircular Open channel

The discharge measurement is significant in wide engineering applications such as water conveyance, sewer system, irrigation, and drainage system. Many devices are designed to measure discharge in partially filled circular and semicircular channels. In this study new semicircular mobile flume depends on the concept of developing a contracted zone to have a control section was examined. The contraction was made by installing a vertical pipe with axial holes at the semicircular open channel to create critical flow. To evaluate the efficiency of this type of devices mathematical and experimental studies were presented. Specific energy, discharge, and Froude number equations were used to deduce the mathematical model. Experimental work was carried out in measuring the discharge values with known specific energy values. The experimental data was used to evaluate the mobile device to measure discharge. New equations for both discharge and discharge coefficient were presented. The verification leaded to have a discharge correction equation to calculate the discharge based on the contraction ratio and the measured water depth in the vertical pipe. Results of the comparison showed that the proposed model provided a reliable prediction of the discharge with high accuracy and maximum error up to 8.7%.

Dynamics of a steady liquid flow in a rim bounding a falling wall film: Influence of aerodynamic effects

After breakup and emergence of a three-phase contact line, an aerodynamically driven surface-bound liquid film contracts in a characteristic triangular manner to eventually feed a rivulet. The dynamics in this film contraction zone is described experimentally and analytically where two side rims can be identified, framing a center region of thin-film flow. The side rims show a converging shape, thus defining the overall appearance of the film contraction zone.