Layer Compressibility Research Articles

Evaluating gloved hand performance based on the mechanical properties of the applied material

The hands are the most complex organs of the body for performing various activities. Therefore, it is critical to protect them against dangers. Protective gloves can reduce or prevent injuries, but they can downgrade hand performance in various aspects, including tactile sensitivity, strength, grip force and hand dexterity. In this study, eight protective gloves with different designs and materials were made. The study investigated the influence of the number of layers and several characteristics, e.g., mass per square meter, thickness, bending stiffness and compressibility, on the gloved hand performance regarding protection ability, tactile sensitivity, strength capability and manual dexterity. The results indicated that despite the improving effects of increasing layer thickness, weight, bending energy and compressibility on protection ability, the gloves diminish tactile sensitivity, grip and pinch force, and manual dexterity. Therefore, it is necessary to select an optimum design to ensure a satisfactory trade-off between protection and performance.

Confinement and magnetic-field effect on chiral ferroelectric nematic liquid crystals in Grandjean-Cano wedge cells.

We explore the structure and magnetic-field response of edge dislocations in Grandjean-Cano wedge cells filled with chiral mixtures of the ferroelectric nematic mesogen DIO. Upon cooling, the ordering changes from paraelectric in the cholesteric phase N^{*} to antiferroelectric in the smectic SmZ_{A}^{*} and to ferroelectric in the cholesteric N_{F}^{*}. Dislocations of the Burgers vector b equal to the helicoidal pitch P are stable in all three phases, while dislocations with b=P/2 exist only in the N^{*} and SmZ_{A}^{*}. The b=P/2 dislocations split into pairs of τ^{-1/2}λ^{+1/2} disclinations, while the thick dislocations b=P are pairs of nonsingular λ^{-1/2}λ^{+1/2} disclinations. The polar order makes the τ^{-1/2} disclinations unstable in the N_{F}^{*} phase, as they should be connected to singular walls in the polarization field. We propose a model of transformation of the composite τ^{-1/2} line-wall defect into a nonsingular λ^{-1/2} disclination, which is paired up with a λ^{+1/2} line to form a b=P dislocation. The SmZ_{A}^{*} behavior in the in-plane magnetic field is different from that of the N_{F}^{*} and N^{*}: the dislocations show no zigzag instability, and the pitch remains unchanged in the magnetic fields up to 1 T. The behavior is associated with the finite compressibility of smectic layers.

Sound, Superfluidity, and Layer Compressibility in a Ring Dipolar Supersolid.

We propose a protocol to excite the Goldstone modes of a supersolid dipolar Bose-Einstein condensed gas confined in a ring geometry. By abruptly removing an applied periodic modulation proportional to cos(φ), where φ is the azimuthal angle, we explore the resulting oscillations of the gas by solving the extended Gross-Pitaevskii equation. The value of the two longitudinal sound velocities exhibited in the supersolid phase are analyzed using the hydrodynamic theory of supersolids at zero temperature, which explicitly takes into account both the superfluid and the crystal nature of the system. This approach allows for the determination of the layer compressibility modulus as well as of the superfluid fraction, f_{S}, in agreement with the Leggett estimate of the nonclassical moment of inertia.

A hierarchy of asymptotic models for a fluid-loaded elastic layer

A hierarchy of asymptotic models governing long-wave low-frequency in-plane motion of a fluid-loaded elastic layer is established. In contrast to a layer with traction-free faces, modelled by Neumann boundary conditions, a fluid-loaded one assumes more involved conditions along the interfaces, dictating a special asymptotic scaling. The latter corresponds to a fluid-borne bending wave, controlled by elastic stiffness of the layer and fluid inertia. In this case, the transverse inertia of the layer and fluid compressibility do not appear at zero-order approximation. The first-order approximation is associated with a Kirchhoff plate, immersed into incompressible fluid. In the studied free vibration setup, the fluid compressibility has to be taken into account only at third order, along with elastic rotary inertia. Transverse shear deformation enters the second-order approximation along with a few other corrections. The conventional impenetrability condition has to be also refined at second order. Dispersion relations corresponding to the developed asymptotic models are compared with the polynomial expansions of the full dispersion relation, obtained from the plane-strain problem of linear elasticity.

A One-Dimensional Nonlinear Consolidation Analysis of Double-Layered Soil with Continuous Drainage Boundary

Based on the soil nonlinearity assumptions proposed by Mesri, the one-dimensional nonlinear consolidation of double-layered soil is investigated. To better align with engineering reality, a continuous drainage boundary is introduced, bolstering the reliability of the derived solution through comparison against existing findings. Subsequently, the consolidation behavior of double-layered soil is analyzed for the soil permeability, compressibility, nonlinear parameters, and interface parameters. The outcomes elicit a positive correlation between the consolidation rate of the double-layered soil and both the ratio of permeability coefficient from the lower to upper soil layers and the value of the interface parameter. Furthermore, it is observed that a lower compressibility coefficient ratio between the lower and upper soil layers, along with a reduced ratio of compression index to penetration index, both contribute to an increased consolidation rate within the context of double-layered soil. The one-dimensional nonlinear consolidation of double-layered soil is intricate, intertwined with the relative permeability and compressibility of soil layers, and the influence of nonlinear parameters and drainage boundary configuration. Integrating these factors is crucial for analyzing the consolidation traits of double-layered soil, leading to a more precise portrayal of the consolidation behavior of coastal soft soils.

Bioinspired Engineering of Fillable Gradient Structure into Flexible Capacitive Pressure Sensor Toward Ultra-High Sensitivity and Wide Working Range.

Tactile sensing is required for electronic skin and intelligent robots to function properly. However, the dielectric layer's poor structural compressibility in conventional pressure sensors results in a limited pressure sensing range and low sensitivity. To solve this issue, a flexible pressure sensor with a crocodile-inspired fillable gradient structure is provided. The fillable gradient structure and grooves in the pressure sensor accommodate the deformed microstructure that permits the enhancement of the media layer compressibility via COMSOL finite element simulation and optimization. The pressure sensor exhibits a high sensitivity of up to 0.97kPa-1 (0-4kPa), a wide pressure detection range (7Pa-380kPa), and outstanding repeatability. The sensor can detect Morse code, robotic grabbing, and human motion monitoring. As a result, flexible sensors with a bionic fillable gradient structure pave the way for wearable devices and offer a novel method for achieving highly precise tactile perception.

Elastic response of colloidal smectic liquid crystals: Insights from microscopic theory.

Elongated colloidal rods at sufficient packing conditions are known to form stable lamellar or smectic phases. Using a simplified volume-exclusion model, we propose a generic equationof state for hard-rod smectics that is robust against simulation results and is independent of the rod aspect ratio. We then extend our theory by exploring the elastic properties of a hard-rod smectic, including the layer compressibility (B) and bending modulus (K_{1}). By introducing weak backbone flexibility we are able to compare our predictions with experimental results on smectics of filamentous virus rods (fd) and find quantitative agreement between the smectic layer spacing, the out-of-plane fluctuation strength, as well as the smectic penetration length λ=sqrt[K_{1}/B]. We demonstrate that the layer bending modulus is dominated by director splay and depends sensitively on lamellar out-of-plane fluctuations that we account for on the single-rod level. We find that the ratio between the smectic penetration length and the lamellar spacing is about two orders of magnitude smaller than typical values reported for thermotropic smectics. We attribute this to the fact that colloidal smectics are considerably softer in terms of layer compression than their thermotropic counterparts while the cost of layer bending is of comparable magnitude.

Taylor's swimming sheet in a smectic-A liquid crystal.

We calculate the swimming speed of a Taylor sheet in a smectic-A liquid crystal. Assuming that the amplitude of the wave propagating on the sheet is much smaller than the wave number, we solve the governing equationsusing the method of series expansion up to the second order in amplitude. We find that the sheet can swim much faster in smectic-A liquid crystals than in Newtonian fluids. The elasticity associated with the layer compressibility is responsible for the enhanced speed. We also calculate the power dissipated in the fluid and the flux of the fluid. The fluid is pumped opposite to the direction of the wave propagation.

The use of modelling to determine the limiting conditions for resuming soil loading by tractor in an area of sugar cane under reduced tillage

The marked growth of the sugar and alcohol sector has promoted an increase in the fleet of heavy agricultural vehicles to meet the demand for commodities; however, the intense traffic of machines in areas of insufficient soil moisture has resulted in compaction, compromising the productivity of the sugar cane. In order to determine the optimal conditions for resuming the use of tractors under a reduced tillage system, the bearing capacity was evaluated and stress distribution was modelled in a dystroferric Red Latosol cultivated with sugar cane. Soil sampling was carried out during the first ratoon crop at 120 days, using metallic cylinders installed at a depth of 0.05 m in the crop rows and 0.15 m between rows. The samples were submitted to the uniaxial compression test to determine the preconsolidation pressure of the soil. The reduced tillage gave the lowest bearing capacity at the soil surface (0.05 m), while the highest values ​​were found at a depth of 0.15 m. The bearing capacity proved to be an efficient indicator for analysing the structural degradation of the soil by demonstrating the compressibility of the various layers and sampling positions resulting from reduced tillage and the impact of agricultural machines in the field. The prediction model for traction and soil stress distribution that was employed was able to predict the optimal performance of the tractor, and provide stress data that would allow a study of the limiting water content for the traffic of agricultural tyre tractors.

Triboelectric Nanogenerators: Enhancing Performance by Increasing the Charge-Generating Layer Compressibility.

Triboelectric nanogenerators (TENGs) have received significant attention for next-generation wearable electronics due to their simple device structure and low cost. Although the performance of TENGs is intimately tied to compressibility effects in the charge-generating layer, achieving high compressibility with conventional elastomers is challenging because molecular entanglements place a lower bound on the softness of cross-linked networks. Here, we demonstrate that bottlebrush elastomers are efficient charge-generating layers that improve the output performance of TENGs, including voltage, current, and surface potential, by minimizing entanglements and decreasing the compressive modulus (E). For example, a cross-linked bottlebrush with poly(dimethylsiloxane) side chains yielded TENGs with an output voltage (120 V) more than two times larger than a linear PDMS network (55 V). In conclusion, this study highlights the advantage of designing new charge-generating layers with improved compressibility to enhance TENG performance.

Studying the consolidation settlement for multi-layered foundation concerning the change in compressibility within the settlement zones

This paper deals with the approach of predicting the consolidation settlement for a multi-layered foundation concerning the change in the compressibility of the settlement layers. This non-linear problem is preliminarily solved by using the Massachusetts Institute of Technology’s (MIT’s) suggestion of approximation, according to which every two layers are converted into a single layer having an equivalent coefficient of consolidation Cv. This paper aims to further the solution by considering the variation of the permeability in the settlement zones of each compressible layer as a change in the compressibility and coefficient of compression. During consolidation, the new value of k is updated, resulting in a new coefficient of consolidation Cv and mv simultaneously; then compressible layers are combined and converted into either equivalent properties or thickness of consolidation. In case the coefficient of volume compression mv is kept to be constant, and the change in the compressibility of the settling zone is taken into account as in this study, preliminary results on the settlement of the alternatives indicate that the consolidation settlement will be greater than that of the conventional approach of analysis and the numerical computation by Plaxis model. The results of the comparison between this study and those of the other models _that are assumed to yield the same time-dependent consolidation_ and numerical model Plaxis indicate that the consolidation for multi-layered foundation requires a more rigorous study. This is a more detailed modification for coming closer to a conservative prediction of the time of consolidation and final consolidation settlement.

Effect of salinity and temperature on the extraction of extracellular polymeric substances from an anaerobic sludge and fouling in submerged hollow fibre membranes

The results of the characterisation of anaerobic sludge-derived extracellular polymeric substances (EPS) under different extraction conditions and their effects on the fouling in submerged hollow fibre membranes are presented. A wide range of EPS extraction results was obtained depending on the extraction conditions. Proteins, polysaccharides, and humic substances represented 80–99% of the total organic matter extracted, with 54–60% identified as humic substances. Ultrasonication was more effective than vortex agitation, ensuring higher EPS extraction yields in a shorter contact time. The increase in temperature from 30 °C to 50 °C and the decrease in NaCl concentration favoured the EPS diffusion, but this positive temperature effect was negligible for an ultrasonic contact. Linear, quadratic, and combined effects of ultrasonication time and solvent salinity were statistically significant effects for ultrasonication-assisted EPS extraction. The highest extraction yield was achieved using ultrasonication at 30 ºC for at least 60 min with salt-free water as the solvent, and an EPS extract with 138.8 mg TOC/L was obtained. Batch ultrafiltration-backwash tests at different permeation rates allowed to determine the specific resistance to filtration of the EPS extracts, which increased from 103.8·10 12 m/kg TOC to 169.4·10 12 m/kg TOC in presence of 1.8 wt% of NaCl. Salinity also provided rigidity to the EPS gel layer, reducing the compressibility index from 0.23 to 0.03. • Ultrasonication and salt reduction favoured the diffusion of EPS. • Maximum EPS extraction required over 60 min of ultrasonication with salt-free water. • Humic substances were the predominant EPS in the side stream AnMBR sludge. • Salt increased the specific resistance and decreased the gel layer compressibility. • The retention degree increased with EPS and salt concentration.

Acoustic streaming in second-order fluids

In this article, inner acoustic streaming for second-order fluids has been studied analytically by employing asymptotic expansions for a thin Stokes layer and low acoustic Mach number. In addition, a multiple-timescale approach has been adopted to separate the primary oscillatory flow and the steady acoustic streaming. The study considers two sample cases: (i) motionless boundary and (ii) vibrating boundary and compares the characteristics associated with their streaming. It is observed that both the primary oscillatory flow and acoustic streaming flow fields are suppressed in second-order fluids due to the extra stress components present in the fluids. This study considers both compressible and incompressible Stokes layers to bring out the acoustic streaming characteristics associated with fluid compressibility. For the compressible Stokes layer, stronger acoustic streaming flow results for the motionless boundary, leveraging the deeper interaction between the primary oscillatory pressure field and the steady streaming. In the case of a vibrating boundary, the primary oscillatory pressure field is independent of the Stokes layer compressibility, and hence, the acoustic streaming flow remains unaltered. The extra stresses in second-order fluids reduce the acoustic body force density, and the maximum reduction has been observed for the vibrating boundary. In order to understand Lagrangian streaming, Stokes drift has also been calculated and compared for all the scenarios. The theoretical analysis and fundamental insights derived from this study have potential for applications in diverse fields such as particle manipulation, biosensing, cell sorting, and removal of loosely bound material such as non-specifically bound proteins.

Pressure-induced isostructural electronic topological transitions in 2H-MoTe2: x-ray diffraction and first-principles study

Synchrotron x-ray diffraction measurements on powder 2H-MoTe2 (P63/mmc) up to ∼46 GPa have been performed along with first-principles based density functional theoretical analysis to probe the isostructural transition in low pressure regime and two electronic topological transitions (ETT) of Lifshitz-type in high pressure regime. The low pressure isostructural transition at ∼7 GPa is associated with the lattice parameter ratio c/a anomaly and the change in the compressibility of individual layers. The pressure dependence of the volume by linearizing the Birch–Murnaghan equation of state as a function of Eulerian strain shows a clear change of the bulk modulus at the ETT pressure of ∼20 GPa. The minimum of c/a ratio around 32 GPa is associated with the change in topology of electron pockets marked as second ETT of Lifshitz-type. We do not observe any structural transition up to the maximum applied pressure of ∼46 GPa under quasi-hydrostatic condition.

Repair of Osteochondral Defects With Predifferentiated Mesenchymal Stem Cells of Distinct Phenotypic Character Derived From a Nanotopographic Platform

Background: Articular cartilage has a zonal architecture and biphasic mechanical properties. The recapitulation of surface lubrication properties with high compressibility of the deeper layers of articular cartilage during regeneration is essential in achieving long-term cartilage integrity. Current clinical approaches for cartilage repair, especially with the use of mesenchymal stem cells (MSCs), have yet to restore the hierarchically organized architecture of articular cartilage. Hypothesis: MSCs predifferentiated on surfaces with specific nanotopographic patterns can provide phenotypically stable and defined chondrogenic cells and, when delivered as a bilayered stratified construct at the cartilage defect site, will facilitate the formation of functionally superior cartilage tissue in vivo. Study Design: Controlled laboratory study. Methods: MSCs were subjected to chondrogenic differentiation on specific nanopatterned surfaces. The phenotype of the differentiated cells was assessed by the expression of cartilage markers. The ability of the 2-dimensional nanopattern-generated chondrogenic cells to retain their phenotypic characteristics after removal from the patterned surface was tested by subjecting the enzymatically harvested cells to 3-dimensional fibrin hydrogel culture. The in vivo efficacy in cartilage repair was demonstrated in an osteochondral rabbit defect model. Repair by bilayered construct with specific nanopattern predifferentiated cells was compared with implantation with cell-free fibrin hydrogel, undifferentiated MSCs, and mixed-phenotype nanopattern predifferentiated MSCs. Cartilage repair was evaluated at 12 weeks after implantation. Results: Three weeks of predifferentiation on 2-dimensional nanotopographic patterns was able to generate phenotypically stable chondrogenic cells. Implantation of nanopatterned differentiated MSCs as stratified bilayered hydrogel constructs improved the repair quality of cartilage defects, as indicated by histological scoring, mechanical properties, and polarized microscopy analysis. Conclusion: Our results indicate that with an appropriate period of differentiation, 2-dimensional nanotopographic patterns can be employed to generate phenotypically stable chondrogenic cells, which, when implanted as stratified bilayered hydrogel constructs, were able to form functionally superior cartilage tissue. Clinical Relevance: Our approach provides a relatively straightforward method of obtaining large quantities of zone-specific chondrocytes from MSCs to engineer a stratified cartilage construct that could recapitulate the zonal architecture of hyaline cartilage, and it represents a significant improvement in current MSC-based cartilage regeneration.

Vacuum preloading, an alternative soft ground improvement technique for a sustainable development

Preloading with soil surcharging in combination with prefabricated vertical drain is one of the common methods used in improving high compressibility and low shear strength of soft soils, particularly in improving very soft to soft clay. One of the main issues of this technique is it requires a high volume of backfill material to apply the surcharging, hence, whenever the availability of the backfill material is scarce or remote, it becomes expensive. In such a case, vacuum preloading becomes one of the best options to be applied in alleviating the high compressibility and low shear strength of the soft clay layers. This vacuum technique also helps to create a sustainable environment as it omits the needs of a high volume of backfill material. Therefore, no hills cutting or ground excavation is required. This paper presents the difference between surcharging and vacuum preloading methods, the working principle, and installation of vacuum preloading. Case histories in improving the soft soils of in low land areas, a large residential located on high ground about 700m from sea level, and a highway construction projects are presented. The case histories revealed that proper application of vacuum preloading could effectively improve soft clays, be in a low land area or high ground area. The depth improved can reach as deep as 25m.

Characteristics of coconut protein separation process by means of membrane ultrafiltration

AbstractCross‐flow ultrafiltration has been reported as a promising technique to concentrate the coconut protein in the liquid by‐product called coconut skimmed effluent, which is produced from coconut oil wet process. However, the cake developed on the membrane surface always causes a measurable resistance, which extremely impedes the filtration efficiency. This study investigated the cross‐flow filtration performance under different operational conditions, which included membrane molecular weight cut‐off (10 and 30 kDa), transmembrane pressure (0.1, 0.2, and 0.3 MPa) and cross‐flow velocity (0.5, 1.0, and 1.5 l/min), and molecular electrostatic interaction by adjusting the feed suspension pH (2.0, 4.0, 6.3, 9.0). The results showed that there was no substantial difference in the filtration performance between 10 kDa and 30 kDa membrane because the number of molecules, in which the particle size was larger than 30 kDa, was high. Furthermore, the results confirmed that the permeate flux increased with the cross‐flow velocity but decreased with the transmembrane pressure due to the cake layer compressibility. For the suspension chemistry effects, although a thick cake layer was developed on the membrane when the feed suspension pH was very close to pI (pH 4.0), the permeate flux was surprisingly greater than the other pH conditions.Practical ApplicationThis research was carried out by focusing on the evaluation of the alternative method other than the traditional one, such as precipitation or centrifugation, for coconut protein concentration. The membrane ultrafiltration, which is widely used to improve the quality of many dairy products, has been applied to the coconut suspension and filtration performances including fouling behavior under various conditions have been investigated. The results obtained could provide extensive information for the operational optimization of the coconut liquor cross‐flow filtration process considering the hydrodynamic factors. Furthermore, since the experiment was conducted with a real polydispersed biopolymer mixture, its unique characteristics that depend on the change of pH would be able to extend the knowledge including the influence of the electrostatic interaction on the cake formation of such plant‐based protein–polysaccharide mixture.

Numerical Aspects Affecting Heat Transfer in ICE Applications and Definition of a Temperature Wall Function Accounting for the Boundary Layer Compressibility

Numerical Aspects Affecting Heat Transfer in ICE Applications and Definition of a Temperature Wall Function Accounting for the Boundary Layer Compressibility

Jolfa Urban Safety audit based on Geographical information system (GIS)

Background: Considering the importance of traffic accidents in cities and the role of non-standard urban roads in increasing them, it is important to detect and reform road safety defects. In order to implement Safe Community Program of Jolfa safe city, a method was introduced for detecting and reform managing of road safety defects. Methods: Urban roads of Jolfa were filmed in eleven separate routes for eight hours by Timestamp Camera software.Safety issues were identified and in eleven layers (Geometric design, sidewalks, lining, pavement, speed bumps, school districts, shopping malls entries, constructions waste, night vision, pedestrian crossings And signs) were entered in GIS.To prioritize reforming actions, the compressibilityof layers of each safety defects category were formed in order toidentify the concentration of each type of road safety defects. If the case of reforming, the operator places this point in modified category and upload the reformed image in GIS.The result of this method was clearly seen in work progress reports. Results: Overly 856 safety issues were identifies in 11 safety categories. Two main area was extracted as prioritized areas with the highest frequency of identified safety issues. The GIS map was presented in the traffic safety committee and action plan was developed for safety promotion interventions. Conclusion: Urban safety audit based on GIS provides a proper information base for city managers about the safety and facilitates the safety management rules for communities who implementing safe community program.

Structural evolution of gypsum under high pressure: single-crystal X-ray experiments revisited

The structures of gypsum at pressures up to approximately 4 GPa are studied with density functional theory (DFT) and thoroughly compared with single-crystal X-ray diffraction experiments reported in the literature [Comodi et al. in (Am Miner 93:1530–1537, 2008)]. It is found that the exchange–correlation density functional revPBE (revised Perdew–Burke–Ernzerhof) in conjunction with a nonlocal van der Waals (vdW) correction is capable of modeling the lattice constants, axial compressibility, and bulk modulus with good accuracy, suggesting that the inclusion of the vdW functional is crucially important for understanding the structure of hydrous minerals. To gain further physical insights, the geometric parameters associated with the constituting components of gypsum (water molecules, SO4 tetrahedra, and CaO8 polyhedra) are analyzed and compared with the experimental values. DFT simulations show that, under pressure, the polyhedral layers remain as nearly planar sheets of interconnecting SO4 tetrahedra and CaO8 polyhedra without further crinkling. DFT analysis on the layer compressibility along the major crystal axis reveals that, in contrast to experimental reports, the hydrous interlayer is less compressible than the polyhedral layer. Squeezed by the lateral pressure, the water molecules in the hydrous interlayer become better affixed along the major axis, making the interlayer harder to compress along this axis.