Passive Properties Research Articles

Study on the compressive performance of hyperelastic seismic isolation materials under passive confinement of surrounding rock simulated by CFRP tubes

Tunnel engineering has played a significant role in the development of human society. However, due to geological constraints, tunnels are prone to losing stability and safety under strong seismic forces. High-elasticity, super-tough polymer-inorganic composite tunnel isolation materials (PTIM), based on polyurethane elastomers, can meet the requirements for tunnel isolation, but research on their passive confinement mechanical properties remains insufficient. This study designed an experimental method to simulate the passive confinement state of tunnel isolation materials. The method uses CFRP tube confinement and core loading to replicate the actual stress conditions within a confined tunnel space. Based on the experimental data, a constitutive model for PTIM under passive confinement was established. The results show that the initial elastic modulus (Ec0) of PTIM and the CFRP confinement stiffness (K) are significantly correlated with the material's stress-strain curve, axial peak stress and strain, circumferential strain, compressive performance, and elastic modulus. Based on these mechanical properties as characteristic values, a tri-linear constitutive model for PTIM with different mix ratios under various confinement stress conditions was established. The high degree of agreement between the predicted data and the experimental data validates the effectiveness of the model.

Modeling implications of the relationship between active and passive skeletal muscle mechanical properties

Modeling implications of the relationship between active and passive skeletal muscle mechanical properties

Effect of skeletal muscle immobilization on regional anisotropic viscohyperelastic properties change in a rat model

Passive mechanical properties in three different zones (distal, proximal, and medial) of biceps brachii immobilized in short position and its free contralateral were investigated. For that, in vitro equibiaxial relaxation tests were performed with samples harvested from skeletal muscles of immobilized rats during one or two weeks. From data obtained in two plane axes of loading, a viscohyperelastic anisotropic model described by a strain energy function coupled with second order Maxwell's model, was used to identify the material parameters. It has been shown that the zone influences the material parameters of the hyperelasticity behavior while the immobilization acts rather on the viscoelasticity response. Based on measurements of histological parameters from flexor carpi ulnaris muscles, we observed that immobilization produced contractile tissue atrophy and connective tissue thickening. The muscle atrophy caused by immobilization could lead to a more linear mechanical behavior along the axis of the muscle fibers. Furthermore, fibrosis, quantified by histological analysis on flexor carpi ulnaris muscles, could result in highly non-linear behavior along the other axis. These structural changes also contribute to an increase in relaxation following immobilization along both axes (+11.7% and +15.5% on average with p < 0.001 and p < 0.01 respectively for each axis). Statement of significanceTo our best knowledge, this work is the first to investigate the anisotropic, viscohyperelastic and heterogeneous properties within a passive skeletal muscle immobilized in a short position. For that, from a rat model, equibiaxial relaxation tests were performed and material parameters were found from a strain energy function coupled with a Maxwell's model. We showed that excising zone of samples greatly influences the parameters of the hyperelastic behavior while the immobilization influences the viscoelasticity response instead. Furthermore, histological analysis permitted to quantify fibrosis in the skeletal muscle and bear out, at least in part, changes in relaxation behavior following immobilization.

Effects of wrist and finger posture on finger independence

Intended actions of one finger produce involuntary movement or force in other fingers. Mechanical and neural factors limit finger independence. The interplay between anatomical factors, wrist and finger postures, and finger independence remain unclear. The purpose of this study was to determine the effects of wrist and metacarpophalangeal (MCP) posture on involuntary finger forces and extensor digitorum (ED) activity. Twenty participants performed submaximal isometric finger extensions in three wrist positions (30° extension, neutral, and 30° flexion) and two MCP postures (straight and 90° flexion). Involuntary index finger force increased with MCP flexion, suggesting the importance of intertendinous connections in finger independence. Consistent with previous research, ED activity was generally higher in wrist extension than neutral and flexed postures. Understanding the role of passive properties within the hand may help us improve finger rehabilitation strategies.

Quantification of Interfacial Voids Using Positron Annihilation Spectroscopy for Mechanism Study on SiCN Bonding and SiN Bonding

Abstract Hybrid bonding for 3D integration requires reliable direct bonding interface of dielectrics. Lately, the spotlight has focused on SiCN/SiCN bonding considering its superior bonding performance by the dangling bonds-facilitated nanovoid closure mechanisms, but it is reported to be sensitive to reactive species especially under the high temperatures. Recent work proposed SiN/SiO2 asymmetric bonding showing a void-free bonding interface and bond energy higher than 2.5 J/m2 as a promising candidate for direct bonding applications. Interestingly, we observed opposite bonding behaviors between SiCN and SiN in corresponding symmetric bonding pair and asymmetric bonding pair (with SiO2). Thus, a comprehensive fundamental understanding on the bonding of different dielectrics is needed to guide the specifications of the bonding layer for enabling a void-free and highly reliable bonding interface. In this study, we systematically quantified the nanovoids in the bonding interface of SiCN/SiCN, SiCN/SiO2, and SiN/SiO2 through positron annihilation spectroscopy and simulation, dangling bond formation by electron spin resonance, and the film passivation property by quasi-steady-state photoconductance. By correlating the film properties and bonding performance, the model of SiCN bonding is extended towards its SiCN/SiO2 asymmetric bonding, and a new model of the nanovoid closure mechanism in SiN bonding is first-time proposed.

Magnetic Induction Tomography for Brain Tissue Imaging Based on Conductivity Distribution for Parkinson’s Disease Diagnosis

Parkinson's disease is a prevalent neurodegenerative complication defined by the accumulation of alpha synuclein lewy bodies in the brain. Misdiagnosis results widespread of Parkinson’s disease because clinical diagnosis is challenging, underlining a need of a better detection technique, such as non-invasive magnetic induction tomography (MIT) technique. Non-invasive techniques for biological tissues imaging are becoming popular in biomedical engineering field. Therefore, MIT technology as a non-invasive technique has been encouraged in a medical field due to its advancement of technology in diagnosing diseases. The measurement parameters in MIT are passive electromagnetic properties (conductivity, permittivity, permeability) for biological tissue and the most dominant parameter in MIT is conductivity properties. It is uses a phase shift between a primary magnetic field and an induced field caused by a target object's conductivity. As a function of conductivity, the phase shift between the applied and secondary fields is expressed. Thus, the phase shift can be used to characterize the conductivity of a target object. The phase shift between the excitation and induced magnetic fields (EMF and IMF) reflects the change in conductivity in biological tissues. This paper focuses on the virtual simulation by using COMSOL Multi-physics for the design and development of MIT system that emphasizes on single channel magnetic induction tomography for biological tissue (bran tissue) imaging based on conductivity distribution for Parkinson’s disease diagnosis. The develop system employs the use of excitation coils to induce an electromagnetic field (e.m.f) in the brain tissue, which is then measured at the receiving side by sensors. The proposed system is capable of indicating Parkinson’s disease based on conductivity distribution. This method provides the valuable information of the brain abnormality based on differences of conductivities of normal brain and Parkinson’s disease brain tissues.

Synaptic communication within the microcircuits of pyramidal neurons and basket cells in the mouse prefrontal cortex.

Basket cells are inhibitory interneurons in cortical structures with the potential to efficiently control the activity of their postsynaptic partners. Although their contribution to higher order cognitive functions associated with the medial prefrontal cortex (mPFC) relies on the characteristics of their synaptic connections, the way that they are embedded into local circuits is still not fully uncovered. Here, we determined the synaptic properties of excitatory and inhibitory connections between pyramidal neurons (PNs), cholecystokinin-containing basket cells (CCKBCs) and parvalbumin-containing basket cells (PVBCs) in the mouse mPFC. By performing paired recordings, we revealed that PVBCs receive larger unitary excitatory postsynaptic currents from PNs with shorter latency and faster kinetic properties compared to events evoked in CCKBCs. Also, unitary inhibitory postsynaptic currents in PNs were more reliably evoked by PVBCs than by CCKBCs, yet the former connections showed profound short-term depression. Moreover, we demonstrated that CCKBCs and PVBCs in the mPFC are connected with each other. Because alterations in PVBC function have been linked to neurological and psychiatric conditions such as Alzheimer's disease and schizophrenia and CCKBC vulnerability might play a role in mood disorders, a deeper understanding of the general features of basket cell synapses could serve as a reference point for future investigations with therapeutic objectives. KEY POINTS: Cholecystokinin- (CCKBCs) and parvalbumin-expressing basket cells (PVBCs) have distinct passive and active membrane properties. Pyramidal neurons give rise to larger unitary excitatory postsynaptic currents in PVBCs compared to events in CCKBCs. Unitary inhibitory postsynaptic currents in pyramidal neurons are more reliably evoked by PVBCs than by CCKBCs. Basket cells form chemical synapses and gap junctions with their own cell type. The two basket cell types are connected with each other.

Heterogeneity in oligodendrocyte precursor cell proliferation is dynamic and driven by passive bioelectrical properties

Oligodendrocyte precursor cells (OPCs) generate myelinating oligodendrocytes and are the main proliferative cells in the adult central nervous system. OPCs are a heterogeneous population, with proliferation and differentiation capacity varying with brain region and age. We demonstrate that during early postnatal maturation, cortical, but not callosal, OPCs begin to show altered passive bioelectrical properties, particularly increased inward potassium (K+) conductance, which correlates with G1 cell cycle stage and affects their proliferation potential. Neuronal activity-evoked transient K+ currents in OPCs with high inward K+ conductance potentially release OPCs from cell cycle arrest. Eventually, OPCs in all regions acquire high inward K+ conductance, the magnitude of which may underlie differences in OPC proliferation between regions, with cells being pushed into a dormant state as they acquire high inward K+ conductance and released from dormancy by synchronous neuronal activity. Age-related accumulation of OPCs with high inward K+ conductance might contribute to differentiation failure.

Enhanced Carrier Selectivity and Superior Passivation in Cost‐Effective Heterogeneous Hybrid Transport Layers for Next Generation Silicon Solar Cells

AbstractHybrid hole transport layers (HHTLs) consisting of‐a low‐cost, low‐temperature, dopant‐free, organic, hole‐selective poly(3,4‐ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS) and an inorganic homogenous tunnel oxides (HoTOs), such as SiOx, TiOx, and AlOx have allowed significant improvements in carrier selectivity as well as in power and cost efficiency. These key parameters can be further improved by introducing heterogeneous tunnel oxides (HeTOs), formed of two different inorganic oxides. This work examines the potential of heterogeneous HHTLs and their impact on passivation as well as on the interfacial properties in silicon solar cells. HeTOs of SiOx/TiOx and SiOx/AlOx with negative fixed charge are studied and optimized. A heterogeneous HHTL with AlOx (&gt;1.5 nm) resulted in a high lifetime (1.2 ms), low surface recombination velocity, and improved surface band bending at the interface due to the presence of higher negative fixed charge (1012 cm−2) within these layers. The passivation properties further improved on light soaking and annealing due to oxidation of PSS and AlOx/SiOx. Overall, these HHTLs demonstrated a hole selectivity (S10) of 12.5 and very high efficiencies up to of 26.1%, surpassing homogenous‐SiOx/PEDOT:PSS by 1.4%.

Alzheimer's disease induced neurons bearing PSEN1 mutations exhibit reduced excitability.

Alzheimer's disease (AD) is a devastating neurodegenerative condition that affects memory and cognition, characterized by neuronal loss and currently lacking a cure. Mutations in PSEN1 (Presenilin 1) are among the most common causes of early-onset familial AD (fAD). While changes in neuronal excitability are believed to be early indicators of AD progression, the link between PSEN1 mutations and neuronal excitability remains to be fully elucidated. This study examined iPSC-derived neurons (iNs) from fAD patients with PSEN1 mutations S290C or A246E, alongside CRISPR-corrected isogenic cell lines, to investigate early changes in excitability. Electrophysiological profiling revealed reduced excitability in both PSEN1 mutant iNs compared to their isogenic controls. Neurons bearing S290C and A246E mutations exhibited divergent passive membrane properties compared to isogenic controls, suggesting distinct effects of PSEN1 mutations on neuronal excitability. Additionally, both PSEN1 backgrounds exhibited higher current density of voltage-gated potassium (Kv) channels relative to their isogenic iNs, while displaying comparable voltage-gated sodium (Nav) channel current density. This suggests that the Nav/Kv imbalance contributes to impaired neuronal firing in fAD iNs. Deciphering these early cellular and molecular changes in AD is crucial for understanding disease pathogenesis.

Electrochemical corrosion behavior and passive film properties of Fe2Ni2CrV0.5Nbx (x=0.2, 0.4, 0.6, 0.8) eutectic high-entropy alloy coating prepared by laser cladding

The phase composition, microstructure morphology, and corrosion behavior of Fe2Ni2CrV0.5Nbx (x=0.2, 0.4, 0.6, 0.8) eutectic high-entropy alloy (EHEA) coatings produced via laser cladding were investigated. The research delved into discerning the phase structures and microstructural variations of the EHEA coatings concerning differing Nb compositions. The findings highlighted a direct correlation between Nb content and the volume fraction of the eutectic structure, specifically the FCC/Laves phases. Electrochemical evaluations, including diverse tests such as potentiodynamic polarization, electrochemical impedance spectroscopy, cyclic polarization, Mott-Schottky measurements, and X-ray photoelectron spectroscopy, revealed distinct corrosion behaviors among the EHEA variants. Notably, the Fe2Ni2CrV0.5Nb0.2 coating exhibited relatively superior corrosion resistance compared with Fe2Ni2CrV0.5Nbx (x=0.4,0.6,0.8) coatings, attributed to its lower corrosion current density (Icorr) and the formation of a thicker passive film with prolonged passivation duration. Conversely, the Fe2Ni2CrV0.5Nb0.8 coating, characterized by increased eutectic structures and grain boundary density, yielded a thicker yet non-uniform passive film with higher vacancy defects. This comprehensive exploration into the corrosion behavior and passive film properties of these EHEA coatings provides a reference for designing materials that hold promising implications for future corrosion-resistant material development in industrial parts repair applications.

Effect of annealing on MoOx and interface properties for carrier-selective contact solar cells with different passivation layers

The structural, electrical and optical properties of molybdenum oxide (MoOx) thin films prepared by magnetron sputtering are studied with annealing temperature. The interface properties of silicon with the intrinsic amorphous silicon (a-Si:H(i)) and alumina (AlOx) passivation layers are investigated by the minority carrier lifetime and implied-Voc (iVoc). The AlOx shows the better passivation properties and thermal stability for the carrier-selective contact solar cells. The Ce-doped In2O3(ICO) is deposited on the surface of MoOx thin films. It is found that the optimized annealing temperature is 125 °C for the carrier selective contact solar cells with the a-Si:H(i) passivation layer. It could increase to 175 °C for the AlOx passivation layer.

Ammonium chloride reduces excitatory synaptic transmission onto CA1 pyramidal neurons of mouse organotypic slice cultures.

Acute liver dysfunction commonly leads to rapid increases in ammonia concentrations in both the serum and the cerebrospinal fluid. These elevations primarily affect brain astrocytes, causing modifications in their structure and function. However, its impact on neurons is not yet fully understood. In this study, we investigated the impact of elevated ammonium chloride levels (NH4Cl, 5 mM) on synaptic transmission onto CA1 pyramidal neurons in mouse organotypic entorhino-hippocampal tissue cultures. We found that acute exposure to NH4Cl reversibly reduced excitatory synaptic transmission and affected CA3-CA1 synapses. Notably, NH4Cl modified astrocytic, but not CA1 pyramidal neuron, passive intrinsic properties. To further explore the role of astrocytes in NH4Cl-induced attenuation of synaptic transmission, we used methionine sulfoximine to target glutamine synthetase, a key astrocytic enzyme for ammonia clearance in the central nervous system. Inhibition of glutamine synthetase effectively prevented the downregulation of excitatory synaptic activity, underscoring the significant role of astrocytes in adjusting excitatory synapses during acute ammonia elevation.

Passive film properties and corrosion resistance of AISI 304L stainless steel

Passive film properties and corrosion resistance of AISI 304L stainless steel

Boron‐Doped Zinc Oxide Electron‐Selective Contacts for Crystalline Silicon Solar Cells with Efficiency over 22.0%

The exploration of wide‐bandgap metal compound films with excellent passivation and contact properties on crystalline silicon (c‐Si) surface, as alternatives to traditional‐doped Si thin films, holds significant promise for the future enhancement of c‐Si solar cell efficiency. Herein, conductive boron‐doped zinc oxide (ZnO:B) films are deposited by atomic layer deposition (ALD) process and investigated as electron‐selective contacts, in combination with a thin SiOx passivating interlayer. This combination demonstrates a relative low contact resistivity of ≈2 mΩ cm2 and improved passivation quality. Further application of this SiOx/ZnO:B stack as a full‐area electron‐selective passivating contact in proof‐of‐concept n‐type c‐Si solar cells results in a satisfactory power conversion efficiency of over 22.0%. This electron‐selective passivating contact structure, prepared via low‐temperature, simplified, and the compositionally controlled ALD process, offers a promising pathway for the development of high‐efficiency and low‐cost c‐Si solar cells.

The corrosion behavior and passive film properties of the cast and annealed AlCoCrFeNi2.1 eutectic high-entropy alloy in sulfuric acid solution

The effect of microstructure on the corrosion behavior and film properties of strengthened AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) was investigated. Annealing of the 80 % cold-rolled AlCoCrFeNi2.1 EHEA at 650–1200 ℃ effectively improved the stable passive region to 930 mV, and decreased the passive current density by 25 % to 3.5 μA/cm2 compared with the cast alloy in 0.1 M H2SO4 solution. The improved corrosion resistance of the annealed AlCoCrFeNi2.1 EHEA was attributed to the increasing oxides proportion and thickness of passive film and the reduced composition difference between FCC and B2 phases. The B2 phase in lamellae suffered the severest corrosion.

Passivation of the positive electrode during the discharge of Li-O2 and O2-assisted Li-CO2 batteries: A comparative study

The effect of passivation of the positive electrode by solid products under discharge is assessed for the first time as one of the factors determining the discharge characteristics of Li-O2 (LOB) and oxygen-assisted Li-CO2 (LCOB) batteries. In order to estimate the passivation, the electrode surface coverage θ by the reaction product (Li2O2 or Li2CO3) is determined on the basis of a decrease in the double-layer capacitance value in the course of the discharge. It is shown that for a given amount of electricity, the electrode surface coverage by Li2CO3 in LCOB is 1.5–2 times that of the coverage by Li2O2 under discharge in LOB. Furthermore, for each of the batteries, achievement of the maximum discharge capacity does not result in the full electrode surface blocking by the discharge products. LCOB manifests higher discharge characteristics than LOB under the kinetic reaction control (in the 100–500 mA g−1 current density range), owing to the accelerated conversion of intermediates and slower solid reaction product deposition on a larger electrode surface area. As the current density increases from 500 to 2000 mA g−1, the discharge capacity of LOB and LCOB decreases, which is mainly due to the effect of diffusion limitations. Moreover, while in the case of LOB the parameter θ decreases, in the case of LCOB it is practically independent of the current density in the studied range. The latter effect may be due to increased passivating properties of Li2CO3 deposits formed under high current density. The results of the work allow considering θ as a new criterion for estimation of the discharge depth and for predicting the characteristics of LCOB and LOB.

The recovery cycle of excitability assessed by a conventional electrodiagnostic machine: A study in healthy volunteers and in Charcot-Marie-Tooth 1A patients

ObjectiveTo validate the ‘paired pulses’ technique with a conventional electrodiagnostic machine (CEM) for studying the axonal excitability recovery cycle (ERC). MethodsPaired pulses, with a variable inter-stimulus interval, were delivered at the wrist along the median nerve. The CEM repeatability was verified in a group of 15 healthy volunteers (test/retest analysis). ERC was then applied in 40 healthy volunteers and 10 patients with Charcot-Marie-Tooth type 1A (CMT1A), using both the threshold tracking (TT) reference method and CEM (basal condition, during and after ischemia). ResultsCEM parameters evaluating absolute refractory and supernormal periods were reproducible (interclass correlation coefficient > 0.75). CEM results were consistent with TT method and literature data. In CMT1A, refractory and superexcitable periods were significantly reduced. According to receiving operator characteristic analysis, the CEM supernormal period area was the most relevant parameter for discriminating CMT1A from healthy volunteers (area under the curve = 0.98). ConclusionsCEM was a valid procedure for studying ERC. CMT1A patients exhibited ERC alterations due to modifications in passive membrane properties and of nodal ion channel distribution resulting from demyelination. SignificanceStudying ERC with CEM could be performed in routine practice in patients with peripheral neuropathies to provide information on motor axonal excitability.

Surface Passivation and Tunable Magnetic Properties of Cr-Based MXenes

Surface Passivation and Tunable Magnetic Properties of Cr-Based MXenes

Ex vivo electrical bioimpedance measurements and Cole modelling on the porcine colon and rectum

Different pathological changes in the large intestine wall, associated with the development of different chronic diseases, including colorectal cancer, could be reflected in electrical bioimpedance readings. Thickness and composition of the mucus bilayer covering it in the luminal side, abundance of bacteria of the intestinal microbiota, the permeability of the epithelium and inflammation are some of these. However, scientific literature on electrical passive properties of the large intestine is scarce. In this study, complex impedance measurements at 8 frequencies were carried out on 6 specimens of porcine colorectal tissue, within half ab hour post-mortem, obtained from a local abattoir. For 5 different distances, measured proximally from the border of the anus, 3 readings were taken at 3 different points with a tetrapolar probe. The results show 2 different dielectric dispersions in the α and β regions and it seems that there is a relationship between the values of resistivities and the thickness of the wall. Also, parameter values both for the Cole and the geometrical models are given. Another set of electrical bioimpedance readings was carried out in order to assess the effect of the mucus layer on electrical properties of the tissue. It seems that these layers are related to the low frequency dispersion. Finally, electrical passive properties of porcine colorectal tissue, reported in this work, give reference values and behaviour patterns that could be applied for further research in human medicine, based on bioimpedance measurements.