Phase Relaxation Research Articles

Estrogen Regulation of PAD2 and Citrullination in the Aging Female Heart

Advanced age is the primary risk factor for heart failure, an enormous public health burden. With aging, men tend to develop systolic dysfunction whereas women are predisposed to develop diastolic dysfunction. Despite these known phenotype differences, underlying molecular mechanisms of sex differences in cardiac aging are unknown. Citrullination, a post-translational modification catalyzed by the peptidylarginine deiminases (PAD) enzyme family, is positively regulated by the sex hormone estrogen (E2) suggesting a potential novel mechanism of age-related cardiac functional changes in women. We hypothesized that PAD expression and citrullination are sexually dimorphic with aging such that as E2 levels decline, so too does citrullination, thus contributing to diastolic dysfunction. We quantified expression of PAD2, the primary cardiac isoform, in female young reproductively competent adult (3 months) and aged (21 months) C57Bl6 mice. Consistent with clinical reports, in our model of aging, female mice developed diastolic dysfunction, with a prolonged linear phase relaxation (54.0 ± 1.7 msec, adult and 66.0 ± 3.3 msec aged, p<0.05). PAD2 expression decreased with age in the female heart, concomitant with decreases in myocardial protein citrullination. To identify potential mechanisms of differential citrullination by age, we performed cit-mass spectrometry. Adult female mice had higher overall citrullination patterns than aged females with enrichment of citrullinated proteins in metabolic, mitochondrial, and sarcomeric pathways. In reproductively competent adult females, cardiac PAD2 expression was higher during estrus compared to diestrus. To confirm direct regulation of PAD2 by E2, a cohort of adult mice underwent ovariectomy (OVX) with or without E2 replacement, provided orally in the water (0.5μM E2) for three weeks. Exogenous E2 supplementation post-OVX increased uterine weight and PAD2 expression, further confirming positive regulation by E2. Together, we suggest that hormonally regulated changes in PAD2 and citrullination with age contribute to sex-specific cardiac aging. Ongoing experiments will directly test the role of PAD2 in the heart by generation of a novel myocyte specific PAD2 deleted mouse across the female lifespan. This abstract was made possible by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under 2P20GM103432. This work was supported by the National Institutes of Health [K01 AG058810 DRB, [K01 AG066845 KCW]. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Neuromorphic one-shot learning utilizing a phase-transition material

Design of hardware based on biological principles of neuronal computation and plasticity in the brain is a leading approach to realizing energy- and sample-efficient AI and learning machines. An important factor in selection of the hardware building blocks is the identification of candidate materials with physical properties suitable to emulate the large dynamic ranges and varied timescales of neuronal signaling. Previous work has shown that the all-or-none spiking behavior of neurons can be mimicked by threshold switches utilizing material phase transitions. Here, we demonstrate that devices based on a prototypical metal-insulator-transition material, vanadium dioxide (VO2), can be dynamically controlled to access a continuum of intermediate resistance states. Furthermore, the timescale of their intrinsic relaxation can be configured to match a range of biologically relevant timescales from milliseconds to seconds. We exploit these device properties to emulate three aspects of neuronal analog computation: fast (~1 ms) spiking in a neuronal soma compartment, slow (~100 ms) spiking in a dendritic compartment, and ultraslow (~1 s) biochemical signaling involved in temporal credit assignment for a recently discovered biological mechanism of one-shot learning. Simulations show that an artificial neural network using properties of VO2 devices to control an agent navigating a spatial environment can learn an efficient path to a reward in up to fourfold fewer trials than standard methods. The phase relaxations described in our study may be engineered in a variety of materials and can be controlled by thermal, electrical, or optical stimuli, suggesting further opportunities to emulate biological learning in neuromorphic hardware.

Ultrahigh energy storage in high-entropy ceramic capacitors with polymorphic relaxor phase.

Ultrahigh-power-density multilayer ceramic capacitors (MLCCs) are critical components in electrical and electronic systems. However, the realization of a high energy density combined with a high efficiency is a major challenge for practical applications. We propose a high-entropy design in barium titanate (BaTiO3)-based lead-free MLCCs with polymorphic relaxor phase. This strategy effectively minimizes hysteresis loss by lowering the domain-switching barriers and enhances the breakdown strength by the high atomic disorder with lattice distortion and grain refining. Benefiting from the synergistic effects, we achieved a high energy density of 20.8 joules per cubic centimeter with an ultrahigh efficiency of 97.5% in the MLCCs. This approach should be universally applicable to designing high-performance dielectrics for energy storage and other related functionalities.

Innovative Design of BNKT-xSLZT Ceramics: Maximizing the Polarization Difference for Enhanced Energy Storage.

Lead-free relaxor ferroelectric ceramics with outstanding energy-storage (ES) density (Wrec) and high ES efficiency (η) are crucial for advanced pulse-power capacitors. This study introduces a strategic approach to maximizing the polarization difference (ΔP) by inducing a transition from the ferroelectric phase to the ergodic relaxor (ER) phase. By employing this strategy, a series of ceramics, (1 - x)(Bi0.5Na0.4K0.1)TiO3-x(Sr0.85La0.1)(Zr0.5Ti0.5)O3 (BNKT-xSLZT), with varying SLZT content (x = 0.05, 0.10, 0.15, and 0.20), were designed. The addition of SLZT enhances cationic disorder, induces vacancies at A sites, and disrupts long-range ferroelectric order, facilitating the formation of polar nanoregions and enhancing relaxor ferroelectric behavior. Furthermore, a viscous polymer process (VPP) technology is employed to optimize the ceramics' structure, aiming to increase the breakdown strength (Eb) and enhance ΔP. Ultimately, enhanced ES performance is demonstrated in BNKT-0.15SLZTVPP, achieving a remarkable Wrec of 6.85 J/cm3 and η of 84% under 470 kV/cm. This composition demonstrates excellent stability with minimal variations in Wrec (3.0%) and η (4.4%) over the temperature range of 20-110 °C. Additionally, BNKT-0.15SLZTVPP exhibits exceptional pulse charge-discharge properties, featuring a high discharge density of 3.72 J/cm3, a large power density of 164.2 MW/cm3, and a short discharge time (t0.9) of 193 ns under 300 kV/cm. The study validates the practicality of BNKT-0.15SLZTVPP for pulse capacitors and underscores the potential to enhance ES performance through A-site donor doping and VPP technology. This work provides a comprehensive understanding of the interplay among composition, structure, and ES properties in lead-free relaxor dielectric ceramics, laying the groundwork for innovative advancements in the field.

Simultaneously enhanced of energy storage and energy harvesting performances of [(Bi0.5Na0.5)TiO3–BaTiO3] ceramics by addition of SrTiO3

As is well known, relaxor dielectrics are characterized by high energy storage efficiency (η), while high recoverable energy storage density (Wrec) can be achieved by anti-ferroelectric ceramics. Herein, our approach is to find relaxor- anti-ferroelectric coexistence phases of (Bi0.5Na0.5)TiO3- BaTiO3 ceramics for achieving high performance in energy storage and energy harvesting as well. Therefore, [(0.9-x) ( Bi0.5Na0.5)TiO3-xSrTiO3-0.1BaTiO3] (abbreviation (0.9-x) NBT-0.1BT-xST) (0.0 ≤ x ≤ 0.4) were synthesized via the solid-state reaction route in air. The tolerance factor (τ) increased from 0.9901 to 0.9998 when ST-content increased from 0.0 to 0.4, indicating an increase in crystal lattice symmetry. The FT-IR de-convolution vibration modes shown in the TiO6 octahedra exhibit two peaks at ∼550 and 650 cm−1, which indicate present coexistence phases of the crystal structure. Ferroelectric to relaxor phase crossover has been detected by the addition of ST with the present anti-ferroelectric phase in particular dopant ST = 0.2. The increasing into the diffused phase transition (γ) is signified by enhancement of the relaxor degree of NBT-BT at high content of ST. The rapidly suppressed remnant polarization (Pr) at high content of ST is due to substitute iso-valence (Sr2+) by tri-valence (Bi3+) and mono-valence (Na1+). Ultrahigh Wrec = 1.13 J/ cm3 with excellent η = 92.62% were obtained at ST = 0.3 at low electric field (E = 110 kV cm−1). A remarkable response of the strain with a high converse piezoelectric coefficient ( d33* = 390.47 pm V−1) at ST = 0.2 was obtained due to decreasing the non-revisable 180° domain switching. Based on the obtained results, the addition of ST to NBT-BT ceramics can provide a head start in the implementation of ceramic capacitors for potential effective into energy harvesting and energy storage applications.

Dielectric relaxation studies in Sm2O3 doped boro-zinc-vanadate glasses

In this work, the conventional melting procedure was adopted to synthesize glasses with a composition of (ZnO)0.3 – (V2O5)0.3 – (B2O3)0.4-x – (Sm2O3)x, x = 0.002, 0.005, 0.007, 0.01 and 0.02 mol%. The dielectric properties of these glasses were measured. The dielectric constant (εʹ) and dielectric loss (εʹʹ) of glasses are found to vary in the range from 1.9177x102 to 3.9456x103 and from 1.5751 to 6.9095x105 respectively for the temperature range 343 K – 573 K and frequency range 50 Hz to 10 MHz. With increase of frequency, both dielectric constant and loss decreased and increased with increase of temperature. The analysis of dielectric constant and dielectric loss confirmed that the phenomenon of dielectric relaxation is mainly due to the frequency-dependent polarization mechanism. Electric modulus and impedence spectroscopy revealed non-Debye type and a single phase relaxation process. Activation energy for dc conductivity and dielectric relaxation are found to be of same size indicating that the potential barrier encountered by the charge carriers is same in both the processes. The master curves suggested that temperature-independent relaxation is occurring in the present glasses. The high values of measured dielectric parameters suggest that the present glasses are suitable in semiconducting and energy storage applications.

Poly(lactic acid)/poly(ε-caprolactone) blends: Separate effects of nanocalcium carbonate and glycidyl methacrylate on interfacial characteristics

To expand the potential applications of polylactic acid (PLA), it is essential to incorporate a highly flexible polymer into the blend. Polycaprolactone (PCL) is an ideal choice due to its ductility and biodegradability. However, blending PLA with PCL resulted in weak mechanical properties. To address this issue, glycidyl methacrylate (GMA) and nano calcium carbonate (NCC) were introduced to enhance the adhesion at the interface between PLA and PCL. Scanning Electron Microscope (SEM) images provided clear visual evidence of the impact of GMA and NCC on the morphology of the blend. Both components were effective in reducing the size of the dispersed PCL phase, shrinking it to approximately half the size of the original blend. Spectroscopic analysis revealed that GMA caused a reaction between its epoxy group and the hydroxyl and carboxyl groups of PLA and PCL. This reaction led to the formation of strong peaks in the 6.5 to 7.5 range in 1H NMR, as well as peaks at 76 and 139 ppm in 13C NMR. These findings were further corroborated by FT-IR, which demonstrated that NCC, despite its surface coating, did not create any new bonds. Rheological studies further demonstrated the positive effects of GMA and NCC. Both the storage modulus (G′) and complex viscosity (η*) of the blends increased, showing improved post-processing performance. Investigation into the shear-thinning behavior of the uncompatibilized blends revealed that NCC caused a significant decrease in complex viscosity at higher frequencies, indicating the disruption of the nanoparticle network. The power-law slope was measured to be 0.62. In contrast, the blend containing the compatibilizer demonstrated a moderate decrease in viscosity, with a power-law slope of 0.36. To analyze the behavior of the PLA/PCL blends in the presence of compatibilizers and nanoparticles at intermediate frequencies, the Palirene model was utilized. The superior integrity of the compatibilized blend was effectively demonstrated by the model, which showed enhanced stress transfer and phase relaxation.

Poly(lactic acid)/ poly(ε-caprolactone) blends: the effect of nanocalcium carbonate and glycidyl methacrylate on interfacial characteristics

To expand the potential applications of polylactic acid (PLA), it is essential to incorporate a highly flexible polymer into the blend. Polycaprolactone (PCL) is an ideal choice due to its ductility and biodegradability. However, blending PLA with PCL resulted in weak mechanical properties. To address this issue, glycidyl methacrylate (GMA) and nano calcium carbonate (NCC) were introduced to enhance the adhesion at the interface between PLA and PCL. SEM images provided clear visual evidence of the impact of GMA and NCC on the morphology of the blend. Both components were effective in reducing the size of the dispersed PCL phase, shrinking it to approximately half the size of the original blend. Spectroscopic analysis revealed that GMA caused a reaction between its epoxy group and the hydroxyl and carboxyl groups of PLA and PCL. This reaction led to the formation of strong peaks in the 6.5 to 7.5 range in 1H NMR, as well as peaks at 76 and 139 ppm in 13C NMR. These findings were further corroborated by FT-IR, which demonstrated that NCC, despite its surface coating, did not create any new bonds. Rheological studies further demonstrated the positive effects of GMA and NCC. Both the storage modulus (G′) and complex viscosity (η*) of the blends increased, showing improved post-processing performance. Investigation into the shear-thinning behavior of the uncompatibilized blends revealed that NCC caused a significant decrease in complex viscosity at higher frequencies, indicating the disruption of the nanoparticle network. The power-law slope was measured to be 0.62. In contrast, the blend containing the compatibilizer demonstrated a moderate decrease in viscosity, with a power-law slope of 0.36. To analyze the behavior of the PLA/PCL blends in the presence of compatibilizers and nanoparticles at intermediate frequencies, the Palirene model was utilized. The superior integrity of the compatibilized blend was effectively demonstrated by the model, which showed enhanced stress transfer and phase relaxation.

A/B-sites disorder-induced relaxor phase transition and inhibit the grain size of BaTiO3 ceramic to enhance energy storage properties

The present study introduces a strategy for improving the energy storage performance (ESPs) and enhancing the dielectric breakdown strength (DBSs) of BaTiO3 (BT) via breaking the domain structure caused by A/B –sites cations disorder. Lead-free [(Ba0.85Bi0.06Mg0.06)(Ti1−xZrx)O3] (abbreviate BT-BMZ) (x = 0.0, 0.025, 0.05, and 0.075) ceramics were used in this study. The substitution of isovalent (Ba2+) by trivalent (Bi3+) in the A-site of BT lattice induced charge misfit and cations disorder. It was balanced by creating barium ion vacancies in the A-site. Replacing Ti4+ with Zr4+ at the B-site of the lattice reduces the tolerance factor (τ), enhances the degree of relaxor phase, and subsequently enhances the DBSs values due to the larger ionic radius of (Zr4+ = 0.72 Å, CN = 6) compared to (Ti4+ = 0.6 Å, CN = 6). Furthermore, the maximum difference polarization (ΔP = Pmax—Pr) is enhanced by the hybridization between Bi3+ 6 P and O2− 2 P instead of Ba2+ 5d and O2− 2 P. [(Ba0.85Bi0.06Mg0.06)(Ti0.95Zr0.05)O3] (BT-BMZ0.05) ceramic (BT-BMZ0.05) exhibit highest recoverable energy storage density (Wrec ∼ 8 J cm−3), energy storage efficiency (η = 86%) and (Eb ∼ 700 kV cm−1). Furthermore, the samples showed wide range stability in the temperature range (25 °C–150 °C ) and the frequency range (2–20 Hz). BT-BMZ0.05 ceramic has significant potential as a viable alternative dielectric for advanced pulsed power capacitors.

A-site disorder induced ferroelectric to relaxor phase transition of Na(Nb0.75Ti0.25)O3 ceramics by Bi3+ for ultra-high energy storage properties

The present work introduces a new insight into effect of A-site disorder to develop the energy storage properties of Na(Nb0.75Ti0.25)O3 ceramic. Lead-free (Na1-xBix)(Nb0.75Ti0.25)O3 (x = 0.0, 0.05 and 0.1) (abbreviated as NNTBx) ceramics were synthesized using solid-state reaction technique. The introduction of Bi3+ shown a significant effect into the crystal structure, dielectric, ferroelectric and energy storage properties of NNT ceramics. The addition of Bi2O3 induced ferroelectric to relaxor phase transition with psedu-cubic crystal structure at 0.1. Significant inhibits of grain size to sub-micrometer has been achieved at 0.1 sample due to lower ionic radius of Bi+3 (1.34 Å, CN=12) to the ionic radius of Na1+ (1.39 Å, CN=12). Meanwhile, the dielectric constant increased from 300 to 1500 when the Bi3+-content increased from 0.0 to 0.1. Effectively increasing in maximum polarization (Pmax) and significant reducing in remnant polarization (Pr) resulting in increasing ΔP (Pmax – Pr) has been obtained at 0.1 content of Bi2O3. This enhancement is attributed to hybridization between Bi3+ 6Pand O2− 2P instead of Na1+ 2S and O2− 3S orbitals. On the other hand, the substitution of monovalent (Na1+) by trivalent (Bi3+) lead to create sodium vacancies into the A-sites of NNT lattice subsequently reducing the Pr value. The tolerance factor (τ) decreased from 0.955 to 0.953 when Bi2O3 increases from 0.0 to 0.1 indicate increasing the cations disorder, charge misfit and relaxor degree of NNT ceramics. The sample with 0.1 of Bi2O3 demonstrate remarkably high energy storage density (Wrec = 17.5 J/cm3), and high relatively energy storage efficiency (n = 80 %) at ultra-high dielectric breakdown strength (Eb = 700 kV/cm). Partially, (NNTB0.1) exhibit an outstanding stability of energy storage properties in terms of temperature (25 to 150 °C) and frequency (2–50 Hz). The variation of Wrec and n were observed about 1 % within the whole range of applied temperature and frequency. These results imply the high potential of (Na0.9Bi0.1)(Nb0.75Ti0.25)O3 ceramic in temperature-stable advanced pulsed power capacitor applications.

Steady-State Supersaturation Distributions for Clouds under Turbulent Forcing

Abstract The supersaturation equation for a vertically moving adiabatic cloud parcel is analyzed. The effects of turbulent updrafts are incorporated in the shape of a stochastic Lagrangian model, with spatial and time correlations expressed in terms of turbulent kinetic energy. Using the Fokker–Planck equation, the steady-state probability distributions of supersaturation are analytically computed for a number of approximations involving the time-scale separation between updraft fluctuations and phase relaxation, and droplet or ice particle size fluctuations. While the analytical results are presented in general for single-phase clouds, the calculated distributions are used to compute mixed-phase cloud properties—mixed fraction and mean liquid water content in an initially icy cloud—and are argued to be useful for generalizing and constructing new parameterization schemes. Significance Statement Supersaturation is the fuel for the development of clouds in the atmosphere. In this paper, our goal is to better understand the supersaturation budget of clouds embedded in a turbulent environment by analyzing the basic equations of cloud microphysics. It is found that the turbulent characteristics of an air parcel substantially affect the cloud’s supersaturation budget and hence its life cycle. This is also shown in the context of mixed-phase clouds where, depending on the turbulent regime, different liquid-to-ice ratios are found. Consequently, the theoretical approach of this paper is crucial to develop tools to parameterize small-scale atmospheric features, like clouds, into global circulation models to improve climate projections for the future.

Light-induced spin-state switching in Fe(II) spin-crossover complexes with thiazole-based chelating ligands.

Homoleptic complexes [Fe(4bt)3](ClO4)2 (1), [Fe(2bt)3](ClO4)2 (2), and [Fe(3tpH)3](ClO4)2 (3) were obtained by a reaction between the Fe(II) precursor salt and the corresponding thiazole-based bidentate ligand (L = 4bt = 4,4'-bithiazole, 2bt = 2,2'-bithiazole, 3tpH = 3-(thiazol-2-yl)pyrazole). X-ray crystal structure determination revealed crystallization of solvent-free complex 1, a solvate 2·MeOH, and a co-crystal 3·2(3tpH). The crystal packing of all these complexes is dominated by one-dimensional interactions between the [Fe(L)3]2+ cations. These interactions are stronger in 2·MeOH and 3·2(3tpH), leading to cooperative and slightly hysteretic transitions between the high-spin and low-spin electronic configurations at ∼235 K and 159 K, respectively. In contrast, weaker intermolecular interactions in 1 result in a gradual spin crossover above 300 K, with the maximum fraction of the HS state ∼25% achieved at 400 K. Complexes 2 and 3·2(3tpH) exhibit light-induced excited spin state trapping (LIESST) under irradiation with white light or a 532 nm laser at 5 K. After the photoexcitation, the trapped metastable HS state relaxes to the ground LS state with the average relaxation temperature of 81 K and 68 K, respectively. Examination of the relaxation dynamics by optical absorption spectroscopy on a single crystal of 3·2(3tpH) revealed the sigmoidal shape of the relaxation curves at lower temperatures, attributed to cooperative effects, as well as a plateau at ∼10% of the HS fraction at intermediate temperatures, hinting at a more complex mechanism for the relaxation of the LIESST phase in this material.

Unveiling the dynamics of phase-transition from ferroelectric to relaxor behavior in Nd-doped BNT-based lead-free piezoelectric ceramics

Nd-doped BNKBT ceramics show a ferroelectric-to-relaxor transition and high piezoelectric performance, demonstrating a balance between ferroelectric and relaxor phases for improved electrical and structural properties in lead-free applications.

High-Precision Quantum Measurements of Qudits Taking into Account the Influence of Amplitude and Phase Relaxation

High-Precision Quantum Measurements of Qudits Taking into Account the Influence of Amplitude and Phase Relaxation

Liquid‐Ice Mass Partitioning Across the Edge of Mixed‐Phase Cumulus Clouds

AbstractOne of the major factors controlling the phase partitioning in mixed‐phase cloud is entrainment mixing, but it is still poorly understood. In this study, the liquid‐ice mass partitioning across the edge of shallow to moderately deep cumulus clouds are analyzed using airborne measurements. The results show the concentration and water content of both liquid and ice decrease toward the cloud edge. However, the liquid mass fraction remains similar across the cloud. The mechanism responsible for the phase partitioning is that extreme inhomogeneous entrainment‐mixing dominates. This is evident as both the droplet and ice sizes remain similar with changing concentrations. The comparison between the time scale of turbulent mixing and the phase relaxation time of water also suggests the turbulence strength is too low to homogenize the cloud. The findings from this study improve our understanding on the role of entrainment in phase partitioning, and are useful in evaluating model simulations.

Phase Conductance of BiFeO3 Film.

In this work, the local conductance of the tetragonal-like (T-like) and rhombohedral-like (R-like) phases of epitaxial BiFeO3 film is systematically studied via conductive atomic force microscopy. At higher tip voltage, there is a mutual transition between the T-like and R-like phases, which could be attributed to the strain relaxation in the T-like phase induced by electric poling, as well as local polarization switching. The T-like phase exhibits a higher conductance, which is related to the lower interface potential barrier between the tip and film surface. Reversible low- and high-current states in the T-like phase can be tuned by polarization switching. These results will be helpful for designing novel nanoelectronic devices, such as voltage and strain sensors.

High-temperature electromechanical actuation of relaxor ferroelectric polymers blended with normal ferroelectric polymer

Soft actuators that can operate at high temperatures are of great interest in emerging research fields such as microfluidics, soft robotics, automotive, aircraft, and bioelectronics. However, most polymer-based flexible actuators suffer from performance degradation at elevated temperatures above 60 °C. In this paper, we present the high-temperature electromechanical actuation of relaxor ferroelectric polymers solution-blended with normal ferroelectric polymers. We conduct a systematic analysis of the electromechanical properties of three unimorph actuators with relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene)s [P(VDF-TrFE-CFE)s] containing different amounts of chlorofluoroethylene (CFE) moieties (approximately 1, 3.5, and 9 wt%). In this study, we propose the film stress, given as Young's modulus times strain, as the measure of the electromechanical performance of soft bending actuators under loading, rather than strain or strain energy density. We demonstrate that a relaxor ferroelectric actuator with 1-wt% CFE, which mixes high-modulus ferroelectric crystal domains with an optimized electrostrictive relaxor phase, develops a high film stress of ∼3.5 MPa. When blended with the normal ferroelectric P(VDF-TrFE), the actuator exhibits excellent film stress of approximately 3.1 MPa at an elevated temperature of 60 °C comparable with that at 25 °C. The high-modulus ferroelectric crystals in P(VDF-TrFE) reinforce the mechanical properties of the actuator at elevated temperatures, generating high-temperature electromechanical actuation with a large strain and strain energy density of approximately 1.6% and 23 mJ/cm², respectively. We also demonstrate successful microfluidic pump operation at 60°C with our actuator using a relaxor ferroelectric polymer blended with an intrinsic ferroelectric polymer.

Study of the effect of multiple phase transformations and relaxation annealing on the microstructure of a martensitic TiNi alloy in different structural states

The work was devoted to studying the effect of multiple phase transformations in the temperature range of phase transformations of a TiNi alloy with a martensitic structure in various initial states - coarse-grained, ultrafine-grained, nanostructured. The conducted studies have shown that in the process of thermal cycling, the accumulation of defects in the crystalline structure occurs - dislocations, which contribute to a decrease in the size of structural elements. Subsequent relaxation annealing, slightly reducing the dislocation density, made it possible to obtain a stable and more equilibrium microstructure, including the nanostructural state.

Operando space-resolved inhomogeneity in lithium diffusion across NMC and graphite electrodes in cylinder-type Li-ion batteries

Homogeneity in Li-ion battery electrodes is a crucial element in obtaining high performance and long cycle life. In this work inhomogeneities in lithium distribution in NMC cathodes and graphite anodes in cylindrical cells have been tracked in real time during cycling, using operando and ex situ high energy X-ray diffraction. A set of 18650 cells having undergone different cycling protocols and at different stages of degradation have been studied during operation at two different C-rates using synchrotron radiation, scanned along the height of the cells. Significant lithium gradients along the height of the cells have been found, with large changes in inhomogeneity over the course of up to 11 charge/discharge cycles performed operando. Lithium inhomogeneity has been found to be different in cathodes and anodes, and depend heavily on degradation state, state of charge, C-rate, and relaxation steps. Phase relaxation during OCV was quantified, such that after charge LiC6+LiC18+C→LiC12, and after discharge LiC12+C→LiC18.

Sex differences in muscle contraction-induced limb blood flow limitations.

To determined sex differences in absolute- and %-reductions in blood flow during intermittent muscular contractions as well as relationships between blood flow reductions and time to task failure (TTF). Thirteen males (25 ± 4 years) and 13 females (22 ± 5 years) completed intermittent isometric trapezoidal forearm flexion at 50% maximal voluntary contraction until task failure. Doppler ultrasound was used to measure brachial artery blood flow (BABF) during the 12-s plateau phase and 12-s relaxation phase. Target torque was less in females than males (24 ± 5 vs. 42 ± 7 Nm; p < 0.001); however, TTF was not different between sexes (F: 425 ± 187 vs. M: 401 ± 158s; p = 0.72). Relaxation-phase BABF at end-exercise was less in females than males (435 ± 161 vs. 937 ± 281mL/min; p < 0.001) but contraction-phase BABF was not different (127 ± 46 vs. 190 ± 99mL/min; p = 0.42). Absolute- and %-reductions in BABF by contraction were less in females than males (309 ± 146 vs. 747 ± 210mL/min and 69 ± 10 vs. 80% ± 6%, respectively; both p < 0.01) and were associated with target torque independent of sex (r = 0.78 and 0.56, respectively; both p < 0.01). Absolute BABF reduction per target torque (mL/min/Nm) and TTF were positively associated in males (r = 0.60; p = 0.031) but negatively associated in females (r = -0.61; p = 0.029). This study provides evidence that females incur less proportional reduction in limb blood flow from muscular contraction than males at a matched relative intensity suggesting females may maintain higher levels of muscle oxygen delivery and metabolite removal than males across the contraction-relaxation cycle of intermittent exercise.