Degree Of Hysteresis Research Articles

Highly Sensitive and Very Stretchable Strain Sensor Based on a Rubbery Semiconductor.

There is a growing interest in developing stretchable strain sensors to quantify the large mechanical deformation and strain associated with the activities for a wide range of species, such as humans, machines, and robots. Here, we report a novel stretchable strain sensor entirely in a rubber format by using a solution-processed rubbery semiconductor as the sensing material to achieve high sensitivity, large mechanical strain tolerance, and hysteresis-less and highly linear responses. Specifically, the rubbery semiconductor exploits π-π stacked poly(3-hexylthiophene-2,5-diyl) nanofibrils (P3HT-NFs) percolated in silicone elastomer of poly(dimethylsiloxane) to yield semiconducting nanocomposite with a large mechanical stretchability, although P3HT is a well-known nonstretchable semiconductor. The fabricated strain sensors exhibit reliable and reversible sensing capability, high gauge factor (gauge factor = 32), high linearity (R2 > 0.996), and low hysteresis (degree of hysteresis <12%) responses at the mechanical strain of up to 100%. A strain sensor in this format can be scalably manufactured and implemented as wearable smart gloves. Systematic investigations in the materials design and synthesis, sensor fabrication and characterization, and mechanical analysis reveal the key fundamental and application aspects of the highly sensitive and very stretchable strain sensors entirely from rubbers.

What Do Monetary Contractions Do? Evidence From An Algorithmic Identification Procedure

As the “Volcker shock” is believed to have generated useful information on the effects of monetary policy, this paper develops a simple procedure to identify other unanticipated monetary contractions. The approach is applied to a panel data set spanning 162 countries (over the period 1970-2017), in which it identifies 147 large monetary contractions. The procedure selects episodes where a protracted period of loose monetary policy was suddenly followed by sizeable nominal interest rate increases. Focusing on contractions of significant size increases the signal-to-noise ratio, while they are unlikely to be accompanied by confounding “information effects” (markets interpreting a rate hike as the Central Bank being optimistic about the real side of the economy). A subsequent panel VAR analysis suggests that a 100-basis point rate hike reduces real GDP by 0.5 percent. This reduction in output seems to be persistent, pointing to a certain degree of hysteresis. The price level falls by 1.5 percent, indicating that the medium-/long-run impact of contractionary monetary shocks is not characterized by a neo-Fisherian response. Advanced economies appear to display more price stickiness than emerging/developing countries, as the former combine a more muted price response with a larger effect on output.

What Do Monetary Contractions Do? Evidence from an Algorithmic Identification Procedure

As the “Volcker shock” is believed to have generated useful information on the effects of monetary policy, this paper develops a simple procedure to identify other unanticipated monetary contractions. The approach is applied to a panel data set spanning 162 countries (over the period 1970-2017), in which it identifies 147 large monetary contractions. The procedure selects episodes where a protracted period of loose monetary policy was suddenly followed by sizeable nominal interest rate increases. Focusing on contractions of significant size increases the signal-to-noise ratio, while they are unlikely to be accompanied by confounding “information effects” (markets interpreting a rate hike as the Central Bank being optimistic about the real side of the economy). A subsequent panel VAR analysis suggests that a 100-basis point rate hike reduces real GDP by 0.5 percent. This reduction in output seems to be persistent, pointing to a certain degree of hysteresis. The price level falls by 1.5 percent, indicating that the medium-/long-run impact of contractionary monetary shocks is not characterized by a neo-Fisherian response. Advanced economies appear to display more price stickiness than emerging/developing countries, as the former combine a more muted price response with a larger effect on output.

Experimental Study on Desorption Hysteresis Characteristic for Shale Gas

Compared with the adsorption isotherms, desorption isotherms could evaluate accurately shale absorbed gas reserves in different pressure stage, the desorption hysteresis characteristics exists in shale gas formation. In order to discover the adsorption hysteresis phenomenon and the influence factor of adsorption hysteresis in high pressure range, The physical properties test and adsorption/ desorption test of shale gas were Carried out by shale outcrop samples from horse Creek group in Eastern Sichuan. The results show that the shale gas adsorption isotherm curve and desorption isotherm curve are not coincided. It has obvious adsorption hysteresis loop, which hysteresis degree relate to shale physical parameter. It shows that the worse shale gas physical property is, the more complicated pore structure is, the more hysteresis degree appears. Meanwhile, three theoretical models were used to fit the measured isotherm adsorption and desorption curves. The results show that comparing to the Langmuir-Freudlich equation and Freundlich equation, Langmuir equation fits the adsorption and desorption characteristic of shale gas betterly.

Hysteresis analysis of Thornton (IP6, IP12E and TH5V) magnetic materials through the use of Arduino microcontroller

Electromagnetic devices have become increasingly important within the manufacturing industries and their applications ranges from memory devices, semiconductors to medical and bio-mechatronics (i.e. in the testing of medicines and observation of human internal organs). However, due to high cost and availability, the equipment capable of measuring the magnetic field of humane treatment and observations are difficult to acquire. This work is carried out to develop resources that can be widely adopted for the purpose of presenting science based medical results involved in bio-mechatronics analysis and present science based instrumentation strategy. Effect sensors were incorporated with an Arduino UNO microcontroller to serve as the interface between the sensors and the material. The basic parameters of an electric, magnetic and electromagnetic field were established for Histeresimetro development. This would reduce the problem of measuring magnetic fields and sort different materials according to their behavior when subjected to electromagnetic fields. The proposed strategy could also be adopted to measure the degree of hysteresis of materials at a lower cost.

Transmittance and Reflectance Studies of Thermotropic Material for a Novel Building Integrated Concentrating Photovoltaic (BICPV) ‘Smart Window’ System

A novel Building Integrated Concentrating Photovoltaic (BICPV) Smart Window has been designed and developed as a next generation intelligent window system. In response to climatic conditions, the smart window varies solar light transmission into the building for provision of light and heat with the reflection of light to the photovoltaic (PV) for electricity generation. This unique function is realised using an integrated thermotropic layer in conjunction with embedded PVs. As commercial PVs are readily available, the success of this novel BICPV design depends solely on the performance of the thermotropic material. This study aimed to develop a suitable reflective thermotropic layer for the proposed smart Concentrating Photovoltaic (CPV) system. A Hydroxypropyl cellulose (HPC) polymer was tested for its applicability as a potential reflective thermotropic material for this purpose. HPC concentration was systematically varied from 1 wt. % to 6 wt. % in aqueous solution so as to provide insight into the relationship between transmittance/reflectance properties, the concentration of the thermotropic material and their dependence upon the environmental temperature. The degree of hysteresis of light transmittance upon subjecting HPC to heating and cooling cycles was also investigated. Specifically, for the HPC liquid samples the measured threshold temperature/transition temperature (Ts) was observed to be approximately 40 °C for 6 wt. % HPC, increasing to approximately 44 °C for 1 wt. % HPC. No hysteresis was observed upon heating and cooling HPC samples. Reflectance below the Ts was recorded at ~10%, increasing up to ~70% above the Ts for 6 wt. % HPC. Finally, a HPC-based hydrogel membrane sample was developed and exhibited good thermotropic activity therefore demonstrating its suitability for use within the BICPV smart window. This study corroborates that HPC is a suitable thermotropic material in the application of next generation BICPV smart window systems.

Dependences of Rheological and Compression Mechanical Properties on Cellular Structures for Impact-Protective Materials.

In this study, three typical impact-protective materials, D3O, PORON XRD, and DEFLEXION were chosen to explore the dependences of rheological and compression mechanical properties on the internal cellular structures with polymer matrix characteristics, which were examined using Fourier transform infrared spectroscopy, thermogravimetric analyses, and scanning electron microscopy with energy dispersive spectroscopy. The rheological property of these three foaming materials were examined using a rheometer, and the mechanical property in a compression mode was further examined using an Instron universal tensile testing machine. The dependences of rheological parameters, such as dynamic moduli, normalized moduli, and loss tangent, on angular frequency, and the dependences of mechanical properties in compression, such as the degree of strain-hardening, hysteresis, and elastic recovery, on the strain rate for D3O, PORON XRD, and DEFLEXION can be well-correlated with their internal cellular structural parameters, revealing, for example, that D3O and PORON XRD exhibit simultaneously high strength and great energy loss in a high-frequency impact, making them suitable for use as soft, close-fitting materials; however, DEFLEXION dissipates much energy whether it suffers a large strain rate or not, making it suitable for use as a high-risk impact-protective material. The rheometry and compression tests used in this study can provide the basic references for selecting and characterizing certain impact-protective materials for applications.

Recombination in Perovskite Solar Cells: Significance of Grain Boundaries, Interface Traps, and Defect Ions.

Trap-assisted recombination, despite being lower as compared with traditional inorganic solar cells, is still the dominant recombination mechanism in perovskite solar cells (PSCs) and limits their efficiency. We investigate the attributes of the primary trap-assisted recombination channels (grain boundaries and interfaces) and their correlation to defect ions in PSCs. We achieve this by using a validated device model to fit the simulations to the experimental data of efficient vacuum-deposited p–i–n and n–i–p CH3NH3PbI3 solar cells, including the light intensity dependence of the open-circuit voltage and fill factor. We find that, despite the presence of traps at interfaces and grain boundaries (GBs), their neutral (when filled with photogenerated charges) disposition along with the long-lived nature of holes leads to the high performance of PSCs. The sign of the traps (when filled) is of little importance in efficient solar cells with compact morphologies (fused GBs, low trap density). On the other hand, solar cells with noncompact morphologies (open GBs, high trap density) are sensitive to the sign of the traps and hence to the cell preparation methods. Even in the presence of traps at GBs, trap-assisted recombination at interfaces (between the transport layers and the perovskite) is the dominant loss mechanism. We find a direct correlation between the density of traps, the density of mobile ionic defects, and the degree of hysteresis observed in the current–voltage (J–V) characteristics. The presence of defect states or mobile ions not only limits the device performance but also plays a role in the J–V hysteresis.

Low-Temperature, Solution-Processed, 3-D Complementary Organic FETs on Flexible Substrate

Vertical stacking of thin-film transistors is an effective way to reduce the footprint of a device, thus increases transistor density in complex flexible electronic applications without reducing the feature size and resolution of the patterning tools. In this paper, we report a 3-D complementary organic FET fabricated on a plastic substrate by stacking a bottom-gate top-contact p-type transistor on a top-gate bottom-contact n-type transistor with a gate shared between the two. We used high-performance polymer semiconductors, poly [(E)-2, 7-bis (2 decyltetradecyl) 4 methyl 9 (5 (2 (5 methylthiophen 2 yl) vinyl) thiophen 2 yl) benzo [lmn] [3, 8] phenanthroline-1, 3, 6, 8 (2H, 7H)-tetraone] for n-type devices and poly [2, 5-bis (7-decylnonadecyl) pyrrolo [3, 4-c] pyrrole-1, 4 (2H, 5H)-dione-(E) 1,2 bis (5 (thiophen 2 yl) selenophen 2 yl) ethene] for p-type devices to fabricate the vertically stacked organic transistors along with a Cytop and cross-linked poly (4-vinylphenol) bilayer and Poly (Methyl Methacrylate) gate dielectric. A 3-D flexible complementary organic inverter exhibits a maximum static voltage gain of $\thickapprox 18$ V/V and high noise immunity of up to 60% of ${V} _{\mathrm {DD}}$ /2. The 3-D transistors show hysteresis-free $I$ – $V$ characteristics despite of low-temperature processes. Moreover, we discuss the influence of cross-linker concentration and the processing temperature of the PVP dielectric film on the degree of hysteresis in $I$ – $V$ characteristics.

Polytherms of the physical properties of metallic melts

The temperature dependence of the kinematic viscosity, electrical resistivity, surface tension, and density of liquid steels and alloys on heating and subsequent cooling is analyzed. On that basis, the polytherms of the physical properties of steels and alloys are systematized. On heating to certain critical temperatures, changes occur in the structure of the melt. Consequently, the cooling polytherms take a form more closely resembling the equilibrium classical laws and do not match the heating polytherms. Branching or hysteresis of the temperature dependences is only irreversible on heating to critical temperatures. Otherwise, partial or complete return to the primary melt structure is possible. That affects the degree of hysteresis of the polytherms. The degree of hysteresis and the data regarding the properties provide qualitative information regarding the transition of the melt structure from the equilibrium to the microhomogeneous state. The uniformity of the distribution of atoms of the alloying elements in microgroupings or clusters indicates the equilibrium of the structure, while the uniformity of the distribution of clusters that differ in structure over the melt volume reflects structural microhomogeneity. Data on the properties of multicomponent metals indicate that, after melting, the variation in melt properties on isothermal holding takes the form of familiar damping oscillations. With increase in temperature, the damping becomes aperiodic, and the relaxation time declines. The processes responsible for the isothermal variation in melt properties occur at the microscopic level. Nonequilibrium industrial metal usually contains inclusions inherited from the initial materials, such as insoluble graphite particles in the cast iron or associations and aggregations of carbide and nitride type. The melt takes a long time to reach equilibrium—usually longer than the time for diffusional mixing of the atoms within the nonequilibrium regions. With more complex chemistry and structure of the solid metal, the distance of the melt from equilibrium will be greater. In this system, new correlations are formed and broken more intensely. Cooperative interactions of the new spatial and time structures with those inherited from the initial materials occur here, as indicated by oscillating behavior of the properties of the metallic melts. Information regarding the state of the melt before solidification permits scientific analysis of the melting points and melting times of the steels and alloys. Such preparation of the melt affects its supercooling, its solidification rate, the formation of hardening phases and eutectics, the segregation of the elements, the dendrite and zonal; structure of the castings, and the overall product quality and production efficiency.

Giant strain with low hysteresis in A-site-deficient (Bi0.5Na0.5)TiO3-based lead-free piezoceramics

We report a giant strain (0.72%) with a low degree of hysteresis (ca. 36.2%) and a giant Smax/Emax ratio (916 pm V−1, Smax and Emax denote the maximum strain and the corresponding electric field, respectively) for lead-free (1−x)(0.8Bi0.5Na0.5TiO3-0.2Bi0.5K0.5TiO3)-xSr0.8Bi0.1□0.1Ti0.8Zr0.2O2.95 piezoceramics with x = 0.06. The giant strain originates from a reversible transition between the ergodic relaxor and ferroelectric states under applied electric fields. A-site vacancies (VA) and oxygen vacancies (VO), deliberately introduced to the system, induce a randomly distributed local polarization field. The local field induces embryonic polarization domains that have a broad distribution of maturity and thus smears the transition between the ferroelectric and relaxor states. This leads to a narrow hysteresis loop. The poling field required for the relaxor-to-ferroelectric transition is reduced significantly, due to the remanent ferroelectric phase at zero field acting as the seed, and the point defects synergistically facilitating the nucleation and growth of the ferroelectric phase. Our work provides a novel route for designing piezoelectric materials with both a giant strain and a narrow hysteresis for practical actuator applications.

Phase Behavior and Self-Assembly of a New Family of Stimulus Responsive Peptide Polymers

Elastin like polypeptides (ELPs), composed of repeats of VPGXG pentapeptides that recur in all tropoelastin sequences, are the best studied class of peptide polymers that exhibit lower critical solution temperature (LCST) phase behavior in water, and these polymers have enabled innovative approaches to nanoparticle self-assembly, cancer therapy, regenerative medicine and protein purification These prototypical ELPs, show aqueous coacervation behavior above their cloud point, leading to the formation of a polymer rich phase and a second, largely aqueous phase. To investigate the origins of coacervation in these systems, we asked the question, how is LCST phase behavior encoded in peptide polymers at their amino acid —primary— sequence level? To understand the sequence determinants of LCST phase behavior, we used bioinformatics to guide the synthesis of a large family of peptide polymers that are predicted to exhibit LCST phase behavior. Analysis of the LCST phase behavior of these polymers provides sequence heuristics to encode LCST phase behavior in intrinsically disordered peptide polymers and enables the design of polymers that encode two orthogonal functions —phase behavior and bioactivity— seamlessly at the primary sequence level. These studies also identified polymers that display tunable degrees of thermal hysteresis in their LCST phase behavior, a property that is exploited for the design of thermal “shape memory” nanoparticles.

Vacuum deposited perovskite solar cells employing dopant-free triazatruxene as the hole transport material

Planar perovskite solar cells using organic charge selective contacts were fabricated. In a vacuum deposited perovskite-based solar cell, dopant and additive free triazatruxene as the hole transport layer was introduced for device fabrication. High open-circuit voltage of 1090mV was obtained using methylammonium lead iodide (Eg=1.55eV) as light harvesting material, thus representing a loss of only 460mV which is in close vicinity of mature silicon technology (400mV). The devices showed a very competitive photovoltaic performance, monochromatic incident photon-to-electron conversion efficiency of 80% and the power conversion efficiencies in excess of 15% were measured with a negligible degree of hysteresis.

Hydrogen-Bonding Modification in Biuret Under Pressure

Biuret (C2H5N3O2) has been studied to 30 GPa by Raman spectroscopy and 50 GPa by X-ray diffraction. Raman peaks exhibit shoulders and splitting that suggests that the molecules undergo reorientation in response to compression. These are observed in three pressure ranges: the first from 3-5 GPa, the second from 8-12 GPa, and finally from 16-20 GPa. The particular modes in the sample that are observed to change in the Raman are strongly linked to the molecular vibrations involving the N-H and the C═O bond, which are most strongly coupled to the hydrogen-bonded lattice structure. The X-ray diffraction suggests that the crystal maintains a monoclinic structure to the highest pressures studied. Although there was a considerable degree of hysteresis observed in some X-ray runs, all the changes observed under pressure are reversible.

Highly Stretchable, Hysteresis-Free Ionic Liquid-Based Strain Sensor for Precise Human Motion Monitoring.

A highly stretchable, low-cost strain sensor was successfully prepared using an extremely cost-effective ionic liquid of ethylene glycol/sodium chloride. The hysteresis performance of the ionic-liquid-based sensor was able to be improved by introducing a wavy-shaped fluidic channel diminishing the hysteresis by the viscoelastic relaxation of elastomers. From the simulations on visco-hyperelastic behavior of the elastomeric channel, we demonstrated that the wavy structure can offer lower energy dissipation compared to a flat structure under a given deformation. The resistance response of the ionic-liquid-based wavy (ILBW) sensor was fairly deterministic with no hysteresis, and it was well-matched to the theoretically estimated curves. The ILBW sensors exhibited a low degree of hysteresis (0.15% at 250%), low overshoot (1.7% at 150% strain), and outstanding durability (3000 cycles at 300% strain). The ILBW sensor has excellent potential for use in precise and quantitative strain detections in various areas, such as human motion monitoring, healthcare, virtual reality, and smart clothes.

Experimental and theoretical characterization of methane and CO2 sorption hysteresis in coals based on Langmuir desorption

Sorption hysteresis is important for primary gas production and CO2 sequestration in coalbed methane (CBM) reservoirs. We represent the degree of hysteresis using an areal hysteresis index (AHI) method incorporating a hysteresis parameter β, representing the ratio of available sorption sites for desorption relative to adsorption. This approach was applied to quantify the gas-coal sorption hysteresis to both methane and CO2 on sub-bituminous and bituminous coals and on anthracite. A theoretical desorption model describes hysteresis based on the molecular dynamic equilibrium between gas adsorption and desorption rates. Volumetric excess ad-/desorption isotherms of methane and CO2 show that adsorption capacities for anthracite are higher than those for the sub-bituminous and bituminous coals over the entire experimental pressure range. Hysteresis for CO2 is greater than for methane for all four coal samples investigated. The relationships between β and Langmuir pressure, Langmuir volume and final equilibrium pressure are weakly negative with null relationships between β and coal properties. Sorption hysteresis is caused by Langmuir pressure and gas type based on theoretical and experimental analyses although its physical mechanism remains unclear. A βCH4−βCO2 plot is proposed as a screening tool to determine likely gas substitution contents for enhanced coalbed methane (ECBM) and CO2 sequestration in coals.

Study on the Coupling Development between Urbanization and Ecosystem-- The Comparative Analysis Based on Guizhou, Yunnan, Hunan and Zhejiang Province

Urbanization and ecological environment coordinated development is the development direction of contemporary urbanization. In this paper, the coupling degree model is used to analyze the coupling degree and coupling coordination degree of Guizhou, Yunnan, Hunan and Zhejiang Province in 2014. The analysis results showed that, four provinces are highly coupled in the coupling degree. Guizhou province is in the low degree of disorder and the lag of urbanization for the coupling coordination degree; Yunnan province is also in a low degree of disorder and urbanization hysteresis; Zhejiang province is in a good coordination, while its urbanization is slightly lagging behind; Hunan province is in a low degree of imbalance, and there is a coordinated development of urbanization and ecosystem. In this paper, the research results help four provinces above to better realize the coordinated development of urbanization and ecological environment.

Tracking the maximum power point of hysteretic perovskite solar cells using a predictive algorithm

The predictive algorithm measures and predicts the steady-state current density for each bias set point, which speeds up the tracking process and measures the true maximum power point, regardless of the degree of hysteresis.

Research progress of ischemic cerebrovascular disease and S-100β, MMP-9

Ischemic cerebrovascular disease is a common and frequently occurring disease in the elderly. It has the characteristics of high disability rate, high mortality rate, and high recurrence rate, which seriously threatens the life and health of the elderly. At present, clinical diagnosis and evaluation are mainly based on medical history, neurological symptoms and signs and imaging examination. The incidence of ischemic cerebrovascular disease is rapid, the existing diagnostic methods have different degrees of hysteresis and limitations in the diagnosis time. Related clinical study found that in the process of ischemic cerebrovascular disease accompanied by serum S-100 beta, matrix metalloproteinase-9 (MMP-9)-related indicators of change. This article reviews the recent progress of S-100 beta and MMP-9 in ischemic cerebrovascular disease. Key words: Brain ischemia/ME; S100 proteins/ME; Matrix metalloproteinase 9/ME; Review

Physical Properties and Effect in a Battery of Safety Pharmacology Models for Three Structurally Distinct Enteric Polymers Employed as Spray-Dried Dispersion Carriers.

Establishing a wide therapeutic index (TI) for pre-clinical safety is important during lead optimization (LO) in research, prior to clinical development, although is often limited by a molecules physiochemical characteristics. Recent advances in the application of the innovative vibrating mesh spray-drying technology to prepare amorphous solid dispersions may offer an opportunity to achieve high plasma concentrations of poorly soluble NCEs to enable testing and establishment of a wide TI in safety pharmacology studies. While some of the amorphous solid dispersion carriers are generally recognized as safe for clinical use, whether they are sufficiently benign to enable in vivo pharmacology studies has not been sufficiently demonstrated. Thus, the physical properties, and effect in a battery of in vivo safety pharmacology models, were assessed in three classes of polymers employed as spray-dried dispersion carriers. The polymers (HPMC-AS, Eudragit, PVAP) displayed low affinity with acetone/methanol, suitable for solvent-based spray drying. The water sorption of the polymers was moderate, and the degree of hysteresis of HPMC-AS was smaller than Eudragit and PVAP indicating the intermolecular interaction of water-cellulose molecules is weaker than water-acrylate or water-polyvinyl molecules. The polymer particles were well-suspended without aggregation with a mean particle size less than 3 μm in an aqueous vehicle. When tested in conscious Wistar Han rats in safety pharmacology models (n = 6–8/dose/polymer) investigating effects on CNS, gastrointestinal, and cardiovascular function, no liabilities were identified at any dose tested (30–300 mg/kg PO, suspension). In brief, the polymers had no effect in a modified Irwin test that included observational and evoked endpoints related to stereotypies, excitation, sedation, pain/anesthesia, autonomic balance, reflexes, and others. No effect of the polymers on gastric emptying or intestinal transit was observed when measured using a barium sulfate tracer material. Finally, in telemetry-instrumented rats the polymers had no effect on acute or 24-h mean blood pressure and heart rate values at doses up to 300 mg/kg. Thus, the properties of the three enteric polymers are appropriate as spray-dried dispersion carriers and were benign in a battery of safety pharmacology studies, demonstrating their applicability to enable in vivo safety pharmacology profiling of poorly soluble molecules during LO.