Effect Of Mechanical Stress Research Articles

Influence of oestrogen deficiency and excessive mechanical stress on condylar head of mandible.

We assessed the aetiology of idiopathic condylar resorption by examining the effects of oestrogen and compressive mechanical stress under a low systemic oestrogen condition in temporomandibular joints (TMJ) caused by an ovariectomy. Female rabbits were divided into non-ovariectomy (non-OVX) and ovariectomy (OVX) groups. A cortical osteotomy was performed with a custom device that was increased in length by 0.25mm every 12hr for 1week after the operation, during which the TMJs in the rabbits received compressive mechanical stress. Samples from both groups were examined with micro-computed tomography and histological staining. Area and depth of bone resorption were both greater in the OVX group. Furthermore, a significantly earlier and greater prevalence of sub-condylar bone resorption was noted in that group, while cells positive for tartrate-resistant acid phosphatase were increased in the OVX group. The present findings suggest that oestrogen induced a much greater amount of bone resorption on the anterior surface of the condylar head at an earlier stage in the TMJs of the present model rabbits. Thereafter, restoration of TMJ function appeared to occur in a normal manner.

Modeling the effect of mechanical stress on bipolar degradation in 4H-SiC power devices

Bipolar degradation, which is caused by the expansion of stacking faults (SFs) during operation, has been a serious issue in 4H-SiC power devices. To evaluate the threshold minority carrier density of SF expansion, ρth, Maeda et al. proposed a theoretical model based on quantum well action and dislocation theory. This model includes SF energy variations, electronic energy lowering due to carrier trapping, and resolved shear stress applied to partial dislocations, τrss. Though the SF energy and the electric energy lowering were quantitatively established, the effect of τrss has not been discussed well yet. In this study, we first conducted theoretical predictions of the effect of τrssonρth. Then, based on our previous experiment on the dependence of threshold current density on mechanical external stress, we investigated the dependence of ρthonτrss. We conducted submodeling finite element analysis to obtain τrss induced by both residual stress due to the fabrication process and experimentally applied external stress. Finally, we obtained ρth at the origin of SF expansion from the experimentally measured threshold current density using device simulation. It was found that the dependence of ρthonτrss was almost linear. Its gradient was −0.04 ± 0.01 × 1016 cm−3/MPa, which well agrees with the theoretical prediction of −0.03 ± 0.02 × 1016 cm−3/MPa. Our study makes possible a comprehensive evaluation of the critical condition of bipolar degradation.

Деформационное поведение сплавов Cu–Al–Mn при воздействии температуры и механических напряжений

Деформационное поведение сплавов Cu–Al–Mn при воздействии температуры и механических напряжений

Surgical stress and cytoskeletal changes in lens epithelial cells following manual and femtosecond laser-assisted capsulotomy.

To study the effect of mechanical stress on the cytoskeleton in lens epithelial cells following conventional phacoemulsification surgery (CPS) and femtosecond laser-assisted cataract surgery (FLACS). The cytoskeleton of the epithelial cells of the anterior lens capsules (ALC) removed by CPS and FLACS was examined by immunohistochemistry. Expression of the intermediate filament, glial fibrillary acidic protein (GFAP), and glutamine synthetase (GS) immunoreactivity were detected. In order to map the actin network of cells, fluorescently labeled phalloidin was used. The samples were examined using confocal laser scanning microscopy. GFAP expression was visible in a larger number of the epithelial cells after CPS compared to FLACS. In CPS sample's epithelial cells, GFAP immunoreactivity indicated robust morphological change. Regarding the actin filaments, the presence of tubular elements connecting epithelial cells, regular actin pattern and marked cortical network after CPS were found. Following FLACS, the actin cytoskeleton of the epithelial cells remained densely structured, and the tubular elements were undetectable, however, the above-mentioned regular actin pattern and the marked cortical network were visible. The conventional removal of the ALC induces more robust changes of the cytoskeleton of the lens epithelial cells.

On the Effects of Mechanical Stress of Biological Membranes in Modeling of Swelling Dynamics of Biological Systems

We highlight mechanical stretching and bending of membranes and the importance of membrane deformations in the analysis of swelling dynamics of biological systems, including cells and subcellular organelles. Membrane deformation upon swelling generates tensile stress and internal pressure, contributing to volume changes in biological systems. Therefore, in addition to physical (internal/external) and chemical factors, mechanical properties of the membranes should be considered in modeling analysis of cellular swelling. Here we describe an approach that considers mechanical properties of the membranes in the analysis of swelling dynamics of biological systems. This approach includes membrane bending and stretching deformations into the model, producing a more realistic description of swelling. We also discuss the effects of membrane stretching on swelling dynamics. We report that additional pressure generated by membrane bending is negligible, compared to pressures generated by membrane stretching, when both membrane surface area and volume are variable parameters. Note that bending deformations are reversible, while stretching deformation may be irreversible, leading to membrane disruption when they exceed a certain threshold level. Therefore, bending deformations need only be considered in reversible physiological swelling, whereas stretching deformations should also be considered in pathological irreversible swelling. Thus, the currently proposed approach may be used to develop a detailed biophysical model describing the transition from physiological to pathological swelling mode.

The Effect of Mechanical Stress on Plant Susceptibility to Pests: A Mini Opinion Review.

Plants are subject to multiple pest attacks during their growing cycle. In order to address consumers’ desire to buy healthy vegetables and fruits, i.e., without chemical residues, and to develop environment-friendly agriculture, major research efforts are being made to find alternative methods to reduce or suppress the use of chemicals. Many methods are currently being tested. Among these methods, some are being tested in order to modify plant physiology to render it less susceptible to pathogen and pest attacks by developing plant immunity. An emerging potentially interesting method that is being studied at this time is mechanical stimuli (MS). Although the number of articles on the effect of MS on plant immunity is still not large, it has been reported that several types of mechanical stimuli induce a reduction of plant susceptibility to pests for different plant species in the case of wounding and non-wounding stimuli. This mini review aims to summarize the knowledge available at this time by raising questions that should be addressed before considering MS as an operable alternative method to increase plant immunity for crop protection.

Effects of mechanical stress on cells derived from human oral mucosa

Abstract Objective When a denture is applied, the oral mucosa is exposed to mechanical stress (MS) including occlusal force via the denture. Clinically, inflammation is occasionally observed in the oral mucosa immediately below the denture despite a proper fit. In this study, we applied MS to cells derived from human oral mucosa and evaluated its effects. Materials and Methods Subconfluent human oral mucosal epithelial cells (HO-1-N-1) and human gingival fibroblasts (HGF) were used to seed 1´105 cells/dish and, after 24 hours, subjected to MS (1 and 3 MPa, 60 min) using a hydrostatic pressurizer. Morphological changes of the cells were examined by Giemsa stain, and changes in cell activity were measured by the WST assay. In addition, mRNA was collected from the cells, and I Inflammatory cytokines and growth factors genes were measured by real-time RT-PCR assay and ELISA. Results HO-1-N-1 showed no morphological change by Giemsa stain but exhibited a significant decrease in cell activity by WST assay. Next, in HO-1-N-1, the expression of Inflammatory cytokines, and ICAM mRNA was significantly increased after MS at 1 MPa but was attenuated at 3 MPa. In HGF, the expression of IL-6 mRNA was enhanced. In HO-1-N-1 and HGF, the IL-6 and IL-8 protein levels increased significantly after MS. Furthermore, in HGF, the EGF and FGF-2 protein levels increased significantly by stimulation at 3 MPa. Discussion MS applied to the oral mucosa immediately below the denture caused a decrease in the activity of oral mucosal epithelial cells and induced enhancement of inflammatory cytokine production. Also, excessive MS was suggested to promote the cure of oral mucosa wounds by promoting the production of growth factors in the oral mucosa.

Conjoint Effects of Chemical and Mechanical Stresses on Fuel Cell PFSA Membranes

During fuel cell operation, proton-exchange membranes (PEMs) are subjected to aggressive chemical environment and mechanical fatigue that alter their properties and may lead to performance loss or, in the worst cases, fuel cell shutdown due to membrane failure. Membrane degradation due to chemical and mechanical stresses remains one of the main factors limiting PEM fuel cell lifetime [1]. Chemical damages are mostly due to radical attacks leading to the scission of the polymer chains (backbone or/and side chains), while mechanical stress comes from repeated swelling/shrinkage cycles caused by the membrane water-uptake. Despite quantities of works focusing independently on chemical (most often) or mechanical (more rarely) degradations, only a few studies were published on the effect of both combined [2]–[4]. Among them, Kusoglu et al. demonstrated that a static compression affects its microstructure and accelerates the chemical decomposition of the polymer chains in Nafion® membranes [2].In this study, we investigate the impact of both chemical and mechanical degradations on the morphology and physicochemical properties of Nafion® membranes: chemical structure, as well as water transport and sorption. The membrane degradation process was induced by a custom-made device that mimics the operating conditions of the fuel cell by exposing the membrane simultaneously to a free radical environment and cyclic compression. The generation of free radical environment is based on the circulation of a continuous flow of hydrogen peroxide or Fenton’s solution (i.e. hydrogen peroxide and ferrous ions), while mechanical fatigue is induced by a cyclic compression to reproduce the swelling/shrinkage sequences entailed by the membrane water-uptake during transient fuel cell operation.Preliminary studies were necessary to determine the appropriate experimental conditions, both from a chemical and a mechanical point of view. Firstly, an investigation similar to the one of Frensch et al. was performed to determine the effect of Fenton’s reagent concentrations on membrane degradation [5]: fluoride emission measurements showed that a higher degradation rate was obtained at a low iron ions concentration. Moreover, at low iron concentration, the degradation rate depended also significantly on the hydrogen peroxide concentration. On the other hand, high hydrogen peroxide concentration (≈ 30 %vol) entailed strong membrane morphology modification with the appearance of many bubbles - with a diameter varying from some micrometers to several millimeters- at the surface of both membranes [6]. Such morphology evolutions cannot be considered as representative of the degradations occurring during fuel cell operation.The first mechanical and chemical degradation tests were carried out using a 0.0503 cm3.s-1 flow of either pure water or 3%vol diluted H2O2 through two thermostated (80°C) half-cells. The half-cells and the membrane were inserted between the clamps of an electromechanical testing machine (MTS load frame model 312.21) and the mechanical stress consisted in a sinusoidal constraint between 0 and 5 MPa at 0.1 Hz. As expected, the application of this sinusoidal constraint increased significantly the degradation rate (Figure): the fluoride emissions were 5 to 7 times higher than under chemical stress only. Indeed, Nafion® XL’s degradation rate increases from 11 µg/h/gNafion to 68 µg/h/gNafion when mechanical stress was applied in addition to chemical stress. Likewise, the values increased from 11 to 54 µg/h/gNafion with NR-211. Moreover, with the combination of cyclic compression and H2O2 solution exposure, the degradation rates approached the values obtained with a Fenton’s reagents exposure.[1] R. Borup et al., Chem. Rev., 107 (10), 3904–3951, 2007.[2] A. Kusoglu et al., ECS Electrochem. Lett., 3 (5), F33–F36, 2014.[3] S. velan Venkatesan et al., J. Electrochem. Soc., 163 (7), F637–F643, 2016.[4] V. M. Ehlinger et al., 166 (7), F3255–F3267, 2019.[5] S. H. Frensch et al., J. Power Sources, 420, 54–62, 2019.[6] S. Mu et al., J. Appl. Polym. Sci., 129 (3), 1586–1592, 2013. Figure 1

Strain Modification of PECVD Nitride By Plasma Immersion Ion Implantation Processes

Strain engineering was introduced in the microelectronics industry almost two decades ago to improve the carrier mobility due to the modification of the band structures in the Metal Oxide Field Effect Transistor (MOSFET) channel [1, 2]. One method to induce local strain in the transistor channel consists in using Contact Etch Stop Layer (CESL) as stress liner. In order to improve both n-MOS and p-MOS performance, the use of a dual stressed liner (DSL) integration is a solution that combines tensile and compressive films on the same wafer [3]. However, the poor mechanical stability of the compressive PECVD nitride layer when exposed to a high thermal budget, combined with the increased integration complexity, limits the interest of the DSL approach. An alternative solution to tackle these limitations consists in locally transforming the tensile CESL nitride into compressive by Plasma Immersion Ion Implantation (PIII).For this study, PIII processes were performed on 300mm silicon bare wafers capped with a 35nm tensile PECVD nitride. Various species (Hydrogen (H), Helium (He) and Nitrogen (N)) implanted at various acceleration voltages (increasing from 1 to 6 in arbitrary units) and doses (A<B<C) were studied using a Pulsion® tool manufactured by IBS. After these processes, the samples were characterized by various techniques such as ellipsometry, bow measurement, Scanning Electron Microscopy observations, Secondary Ion Mass Spectrometry or FTIR analysis.The stress of the various nitride layers was determined by the Stoney formula, using the curvature measurements and the layer thickness determined by ellipsometry, assuming the shift of the bow results only from the change in nitride stress. Results show that, for all the species studied, the PIII process provides the capability to change the nitride stress from initially tensile to neutral or even compressive when increasing the dose and the acceleration voltage (Fig.1). The largest stress modifications were achieved with nitrogen and hydrogen. For the latter however, the blistering of the nitride layer is observed for the highest doses due to an excessive hydrogen concentration, which is prohibitive for further process integration. By using helium PIII process, the stress change is less for identical process parameters (Fig.1), leading to a neutrally stressed nitride layer. Increasing the helium dose to modify the nitride stress further leads to a consumption of the layer, which limits the use of helium only to the reversal of the mechanical stress.To verify that the stress change will remain during the subsequent process steps, curvature measurements were performed after a consequent thermal budget, equivalent to PMD deposition, applied after the PIII processes. The results show no significant change of the stress level.We demonstrated the capability of PIII processes to turn a tensile CESL nitride layer into a compressive one in a reasonable processing time thanks to the high beam current achievable with PIII process, without any consumption of the layer and without the need of a post implantation thermal treatment. Complementary analysis are on-going to fully characterize the impact of each species on the CESL physicochemical properties and thereby understand its stress evolution. Thanks to these encouraging results, the most promising conditions of all the species mentioned above will be experimented on electrical structures to quantify the related static performance gain.This project (OCEAN12) has received funding from the ECSEL Joint Undertaking (JU) under grant agreement No 783127. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and France, Germany, Austria, Portugal, Greece, Spain, Poland.[1] S. Ito, et al, “Mechanical Stress Effect of Etch-Stop Nitride and its Impact on Deep Submicron Transistor Design”, 2000 IEDM Tech. Dig., p. 247[2] T.K. Kang, IEEE ELECTRON DEVICE LETTERS, VOL. 33, NO. 6, JUNE 2012.[3] H. S. Yang, “Dual Stress Liner for High Performance sub-45nm Gate Length SO1 CMOS Manufacturing”, IEDM 2004 Figure 1

Strain induced variability study in Gate-All-Around vertically-stacked horizontal nanosheet transistors

Using physics-based predictive technology CAD simulations, we show the improvements possible in device performance via strain engineering in vertically-stacked horizontal gate-all-around nanosheet Field-Effect transistors (NSFETs), which may outperform conventional FinFETs beyond 7 nm technology node. Effects of mechanical strain on NSFET variability is reported for the first time. We present a novel simulation approach for the analyses of random dopant fluctuation (RDF) and metal grain granularity (MGG) dependent variability in nanosheet transistors. The study encompasses topography simulation, which realistically reproduces a reported experimental nanosheet transistor. Device simulations are based on sub-band Boltzmann transport with 2D Schrödinger equation in the nanosheet cross-section and 1D Boltzmann transport along the nanosheet channel. The effects of mechanical stress and geometry dependence of the electrical characteristics are also reported. Critical design issues are outlined.

Acute mechanical stress in primary porcine RPE cells induces angiogenic factor expression and in vitro angiogenesis

BackgroundChoroidal neovascularization (CNV) is a major cause of blindness in patients with age-related macular degeneration. CNV is characterized by new blood vessel growth and subretinal fluid accumulation, which results in mechanical pressure on retinal pigment epithelial (RPE) cells. The overexpression of RPE-derived angiogenic factors plays an important role in inducing CNV. In this work, we investigated the effect of mechanical stress on the expression of angiogenic factors in porcine RPE cells and determined the impact of conditioned medium on in-vitro angiogenesis.ResultsThe goal of this study was to determine whether low levels of acute mechanical stress during early CNV can induce the expression of angiogenic factors in RPE cells and accelerate angiogenesis. Using a novel device, acute mechanical stress was applied to primary porcine RPE cells and the resulting changes in the expression of major angiogenic factors, VEGF, ANG2, HIF-1α, IL6, IL8 and TNF-α, were examined using immunocytochemistry, qRT-PCR, and ELISA. An in vitro tube formation assay was used to determine the effect of secreted angiogenic proteins due to mechanical stress on endothelial tube formation by human umbilical vein endothelial cells (HUVECs). Our results showed an increase in the expression of VEGF, ANG2, IL-6 and IL-8 in response to mechanical stress, resulting in increased in vitro angiogenesis. Abnormal epithelial-mesenchymal transition (EMT) in RPE cells is also associated with CNV and further retinal degeneration. Our qRT-PCR results verified an increase in the expression of EMT genes, CDH2, VIM and FN1, in RPE cells.ConclusionsIn conclusion, we showed that acute mechanical stress induces the expression of major angiogenic and EMT factors and promotes in vitro angiogenesis, suggesting that mechanical stress plays a role in promoting aberrant angiogenesis in AMD.

Impact of Uniaxial Stretching on Both Gliding and Traction Areas of Tendon Explants in a Novel Bioreactor.

The effects of mechanical stress on cells and their extracellular matrix, especially in gliding sections of tendon, are still poorly understood. This study sought to compare the effects of uniaxial stretching on both gliding and traction areas in the same tendon. Flexor digitorum longus muscle tendons explanted from rats were subjected to stretching in a bioreactor for 6, 24, or 48 h, respectively, at 1 Hz and an amplitude of 2.5%. After stimulation, marker expression was quantified by histological and immunohistochemical staining in both gliding and traction areas. We observed a heightened intensity of scleraxis after 6 and 24 h of stimulation in both tendon types, though it had declined again 48 h after stimulation. We observed induced matrix metalloproteinase-1 and -13 protein expression in both tendon types. The bioreactor produced an increase in the mechanical structural strength of the tendon during the first half of the loading time and a decrease during the latter half. Uniaxial stretching of flexor tendon in our set-up can serve as an overloading model. A combination of mechanical and histological data allows us to improve the conditions for cultivating tendon tissues.

Conformational Transitions of Receptor Binding Domain of SARS-COV-2 under Mechanical Stress at 0K and Physiological Temperatures

Understanding the workings of the novel coronavirus (SARS-CoV-2) is crucial to develop counter therapeutic measures. SARS-CoV-2 gains entry into human cell by binding its receptor Binding Domain (RBD) of Spike protein (S1) to ACE2 receptors. In order to study the effect of mechanical stress on the RBD of SARS-CoV-2, it is modelled as viscoelastic material using Burgers Model. Strain response of RBD under constant stress is analyzed, which gives useful insights into the conformational transitions of RBD at 0K and physiological temperatures. The theoretical underpinning has shown that with increase in the number of stress cycles, the binding affinities of RBD conformational states to ACE2 receptor decrease, decreasing the binding reaction rate between ACE2 receptor and SARS-CoV-2. This analysis gives theoretical evidence that ultrasonic therapy and photo therapy (UV) can be potential candidates to reduce binding reaction rates between ACE2 and SARS-CoV-2.

Mesoscopic modeling of the mechanically tunable electrical conductivity of ZnO varistors

An electromechanically coupled model for the simulation of electric current flow in ZnO varistors is presented. The model is based on an equivalent circuit representation of the varistor microstructure, where the grain boundaries are modeled as nonlinear resistors in the circuit. This approach extends on previous circuit models by including the effect of mechanical stress on grain boundary conductivity. The 3D mechanical stress distribution in the material is calculated by the finite element method. Using this distribution, the electrical resistance of each grain boundary is determined by applying a self-consistent model for the trapped interface charge induced by piezoelectric polarization. Finally, the electric current flow patterns and the bulk conductivity of the material are computed using the nonlinear circuit model. The simulated IV-characteristics reveal a significant sensitivity of electrical conductivity to applied stress. For 2D and 3D ZnO varistor models, the simulations demonstrate the effect of current concentration along thin conducting paths depending on microstructure properties and on the mechanical stress condition of the material.

Optical tweezers and multimodality imaging: a platform for dynamic single‐molecule analysis

Utilization of single molecule technologies offer researchers the unique opportunity to perform direct real‐time observations and measurements for a plethora of biological mechanisms. Here, we present our efforts to facilitate biologically meaningful discoveries using fully integrated optical tweezers with single‐molecule fluorescence microscopy technology. Correlative fluorescence and optical tweezer microscopy (C‐trap™) is the only technology that truly integrates optical tweezers, confocal/STED microscopy and an advanced microfluidics. The C‐Trap ™ enables live, simultaneous and correlative visualization and manipulation of molecular interactions with sub‐piconewton (pN) force resolution and a kilo‐Hz (to mega‐Hz) temporal resolution, such that even the quickest cellular events can be captured. This technology can be utilized as an easy‐to‐use and stable instrument with the capacity to elucidate biologically meaningful mechanisms. Here we present applications detailing protein (un)folding and conformational changes; DNA‐protein interactions and genome modifications; effects of mechanical stress on DNA/RNA structure; motility of cytoskeletal molecular motors; and protein droplet and aggregation dynamics. These experiments demonstrate technological advances in hybrid single‐molecule methods and the potential for their use in future scientific breakthroughs.

Development of a test plan and a testbed for performance analysis of MEMS-based IMUs under vibration conditions

Micro-Electro-Mechanical Systems (MEMS) are today widespread in many industrial and consumer applications. In the field of terrestrial transportation, cellular, wearable devices, robotics, drone, to cite a few, MEMS-based Inertial Measurement Units (IMUs) are widely employed for assuring several tasks as for the object tracking, self-driving vehicles, human motion and so on. Expected performance of such systems and also recent literature and technical standards miss considering both a context-awareness reliability analysis and metrological performance analyses of MEMS-based IMUs when operating in real scenarios characterized by the presence of significant temperature excursions, humidity, vibrations, mechanical shocks and so on. In particular, standard procedures to be applied for testing MEMS-based IMUs are not still available.Trying to fill these needs, this paper proposes both a suitable testbed and test plans for performance analysis of such kinds of devices under vibration conditions. The application to a real IMUs has confirmed that the proposed tests allow identifying the effects of mechanical stress on both the reliability and metrological performance of such devices. These results could be useful also for the international committees involved in the definition of technical standards to be adopted for testing these kinds of devices.

Effect of compressive mechanical stress on the magnetic properties of LiTiZn ferrite ceramics

In the article, it was experimentally determined that compressive mechanical stress affects the parameters of the temperature dependence of the initial permeability. LiTiZn ferrite ceramics were sintered at 1010 °C for 2 h in air. The experimental curves were mathematically processed using the phenomenological expression to describe the initial magnetic permeability according to the Smith-Wijn model. It is shown that the change in the shape of the experimental curves correlates with the calculated data of the increase in the demagnetizing factor with an increase in mechanical stress. It is hypothesized that the change in the shape of the temperature curves is due to the magnetoelastic effect and the temperature dependence of the magnetostriction constant. Also, it was found that mechanical stress does not affect the X-ray microstructural parameters, including the true physical broadening of the reflexes. At the same time, the growth of mechanical stress to the maximum possible level for such type of ferrite ceramics leads to an increase in the coercive force by 10%. The character of the impact of mechanical stress on the shape of the temperature dependence curve of the initial permeability differs from the effect of non-magnetic Al2O3 additives. Thus the character of the change in the shape of the temperature dependence curve of the initial permeability allows monitoring nonmagnetic phases or mechanical stress in a LiTiZn ferrite ceramics production.

Novel insights on the study of a fifteenth-century oro di metà/Zwischgold gilding by means of ion and electron microscopy: characterization of the stratigraphy avoiding cross-sections preparation

Abstract In this work, an analytical methodology to identify and thoroughly characterize the oro di meta/Zwischgold gilding is reported. Gildings in paintings are commonly studied by means of optical microscopy (OM), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectrometry (SEM-EDS), as well as other techniques, but they all require sample preparation. In this study, a sample of Zwischgold taken from an Italian panel painting of the fifteenth century was thoroughly characterized using Focused Ion Beam (FIB)-SEM sectioning, accessing the layered structure from the surface into depth without further sample preparation. The results achieved were compared to those of a further sample taken from the same area, which was prepared by conventional resin embedding and polishing techniques in order to evaluate the effects of the mechanical stresses induced by resin drying and polishing along the latter process. A more uniform morphology and sharper outlines of the metal layers were observed after FIB milling, likely due to the more accurate and less invasive cutting process. Moreover, since SEM-EDS analysis is limited in terms of resolution to be performed straight on the milled area relative to the thinness of the metal layers, Time of Flight – Secondary Ion Mass Spectrometry (ToF-SIMS) analysis was performed, and allowed revealing two distinct metal layers in the gilding consisting of Au and Ag thus confirming a Zwischgold structure.

Modeling of multi-axial stress dependent iron losses in electrical steel sheets

Modeling the effect of multi-axial mechanical stress on the iron losses of an M400-50A grade non-oriented electrical steel sheet is studied. By utilizing the statistical loss theory, the total measured iron losses are first segregated to hysteresis, classical eddy current and excess losses. Then, the stress dependency of the excess losses is modeled by correlating them to the hysteresis losses under multi-axial stress. This correlation, coupled with a magneto-elastic invariant based loss model, can be used to predict the iron loss evolution with reasonable accuracy under multi-axial stress when only iron loss data under no applied stress at various excitation frequencies and under only two uniaxial stress levels at quasi-static excitation are available. Consequently, this approach significantly reduces the required measurement data for estimating the iron losses under multi-axial stress.

Effect of cross-link concentration on the isotropic to smectic-A phase transition in smectic elastomers

We describe the isotropic to smectic-A phase transition in smectic elastomers within Landau phenomenological theory. We analyze the effects of external mechanical stress and cross-link concentration on the isotropic to smectic-A phase transition. Both the orientational and translational order parameters decrease with the increase of cross-link concentration. The first order isotropic to smectic-A transition in low-molecular-weight materials, can become weak first order transition in smectic elastomers. The effect of cross-link concentration on the strain birefringence and correlation length in the isotropic phase of the transition is discussed.