Low Strain Research Articles

Unraveling the mechanism of alleviating the textural deterioration of thermally sterilized cooked noodles: Effect of gluten content and quality

Thermal sterilization is valuable for creating shelf-stable instant wet cooked noodles; however, it often leads to a poor texture. In this study, seven different reconstituted wheat flours were used to evaluate the impact of gluten content and quality on alleviating the textural deterioration of instant wet cooked noodles. Increasing the gluten content in wheat flour led to a higher hardness of instant wet cooked noodles, and the tensile distance significantly increased from 18.41 to 32.11 mm (p < 0.05). Conversely, as the glu/gli ratio decreased, the hardness decreased from 53.96 to 44.47 N, but the tensile distance significantly increased from 29.24 to 40.75 mm (p < 0.05). The rheological properties showed that a higher gluten content increased the elastic modulus at low strain and a lower glu/gli ratio reduced the deformation ratio at high strain. Size-exclusion high-performance liquid chromatography analysis revealed that less sodium dodecyl sulfate (SDS)-extractable glutenin was retained in the noodles with a high gluten content and more SDS-extractable gliadin was preserved at a low glu/gli ratio. The confocal laser scanning microscopy results showed that a high gluten content induced a compact network and a low glu/gli ratio in wheat flour resulted in a continuous network.

The Use of Waste Synthetic Hair Fibre in Cement Mortar

Cement mortar has low tensile strength and fracture strain; therefore, fibres are used to reinforce cement mortar. Synthetic hair is one of the most neglected of all the residual wastes that cause environmental problems in many developing countries. Therefore, this study used waste synthetic hair fibre in cement mortar production as a way to reduce the environmental effect generated by waste, and also to enhance the strength of the mortar for construction application. The study aimed to investigate the properties of cement mortar reinforced with waste synthetic hair fibres. 0, 2.5, 5, and 7.5% of synthetic hair fibre were used as a replacement for cement by weight in mortar. 100 × 100 × 100 mm cube, and 100mm diameter and 200mm length cylinder specimens were prepared, cured, and tested at ages 7, 14, and 28 days for tensile and compressive strengths, density, and water absorption. The highest compressive strength for the synthetic waste hair fibre reinforced mortar was 8.57N/mm2 as compared to 10.84N/mm2 achieved for the control at 28 days of curing. The synthetic waste hair fibre reinforced mortar achieved the highest tensile strength of 1.80N/mm2 as compared to 1.67N/mm2 achieved by the control at 28 days of curing, representing an increase of about 11% in tensile strength of the synthetic hair fibre reinforced mortar over the control. The highest density for the synthetic hair fibre reinforced mortar was 2114 kg/m3 as compared to the control of 2144 kg/m3. The lowest water absorption for the synthetic hair fibre reinforced mortar was 2.48% as compared to the control of 2.04%, respectively. It is concluded that the properties of cement mortar reinforced with waste synthetic hair fibres are acceptable for construction application and recommended that practitioners use 2.5% waste synthetic hair as a partial replacement for cement in producing mortar.

Hot deformation behavior and microstructural evolutions of a Mg-Gd-Y-Zn-Zr alloy prepared by hot extrusion

The hot deformation behavior of extruded Mg-9.5Gd-4Y-2Zn-0.5Zr alloy was studied through hot compression tests conducted at deformation temperatures of 350–500 °C and strain rates of 0.001–1 s−1. Under most deformation conditions, the flow stress first reached a maximum before decreasing to a stable value, demonstrating characteristics of dynamic recrystallization (DRX). The constitutive equation of the alloy was established as ε.=1.03*1011sinh0.01287*σp2.422exp(−171150/RT) through calculations and derivation. The influences of the deformation temperature and strain rate on the microstructure and DRX of the alloy during the hot compression process were investigated using electron backscatter diffraction. It was found that at temperatures between 350 °C and 450 °C, the alloy texture exhibited multiple {0001} peak rings distributed around the normal axis of the compression direction. When the strain rate was 0.001 s−1, the average equivalent grain diameter significantly increased from 3.3 μm to 22.4 μm with the rise in deformation temperature, whereas when the deformation temperature was 450 °C, the volume fraction of DRX grains noticeably decreased from 87.6 % to 13.2 % with the increasing strain rate. Further research revealed that due to the restriction of strain rate on grain boundary migration, discontinuous dynamic recrystallization and continuous dynamic recrystallization were the predominant DRX mechanisms at low and high strain rates, respectively.

On the nature of nano twin-induced shear band formation in a dispersion strengthened copper alloy under micro-mechanical loading

A key challenge in metallic alloys with high ductility is understanding how microstructural inhomogeneities influence shear localization, leading to localized plastic deformation and material failure. In this study, we explore the phenomenon of shear localization in coarse-grained copper, a material traditionally regarded as having low susceptibility to such behavior. Contrary to conventional understanding, our findings reveal that microstructural inhomogeneities play a pivotal role in inducing extensive strain localization during low strain rate micro-mechanical loading. The presence of fine precipitate particles leads to strain localization at small strains and low strain rates by activating shear localization driven by void formation mechanisms. Furthermore, nanoscale precipitates act as sites for dislocation pile-up within deformed structures of shear bands, leading to the formation of nano twins within these bands. Consequently, precipitate particles serve a dual role: contributing to strain localization and potential cracking, while also enhancing the alloy’s strength and ductility through nano-twinning mechanisms. This investigation offers a novel perspective on the interplay between material microstructure and deformation behavior, challenging existing paradigms in materials science.

Assessment of the mechanical and functional properties of nitinol alloys fabricated by laser powder bed fusion: Effect of strain rates

Laser Powder Bed Fusion-fabricated (LPBFed) nitinol shape memory alloys (SMAs), which undergo solid-solid phase transitions between austenite and martensite, are increasingly utilized in various technical fields and are subjected to a wide range of strain rates during service. This study pioneers the investigation of a comprehensive range of strain rates (3.16 × 10−6-10°/s), encompassing the strain rates used in quasi-static tensile tests reported in the existing literature, to understand their effects on the deformation mechanisms of LPBFed nitinol SMAs. Utilizing multi-scale characterization, including macroscopic mechanical evaluation, mesoscale analysis of deformation surfaces, and microscale examination of microstructure, we reveal distinct deformation behaviors at different strain rates. At lower strain rates, the mechanical behavior exhibits little sensitivity to changes in the strain rates, with stress-induced martensite transformation or martensite detwinning and variant reorientation being the primary deformation mechanisms. However, at higher strain rates, we observe significant variability in mechanical response, dominated by dislocation-induced slip and reduced occurrence of stress-induced martensitic transformation. This study provides the first comprehensive database for the engineering applications of LPBFed Nitinol SMAs and offers critical insights into optimizing mechanical and functional assessments for these advanced materials.

Mesoporous structured MoS2 as an electron transport layer for efficient and stable perovskite solar cells.

Mesoporous structured electron transport layers (ETLs) in perovskite solar cells (PSCs) have an increased surface contact with the perovskite layer, enabling effective charge separation and extraction, and high-efficiency devices. However, the most widely used ETL material in PSCs, TiO2, requires a sintering temperature of more than 500 °C and undergoes photocatalytic reaction under incident illumination that limits operational stability. Recent efforts have focused on finding alternative ETL materials, such as SnO2. Here we propose mesoporous MoS2 as an efficient and stable ETL material. The MoS2 interlayer increases the surface contact area with the adjacent perovskite layer, improving charge transfer dynamics between the two layers. In addition, the matching between the MoS2 and the perovskite lattices facilitates preferential growth of perovskite crystals with low residual strain, compared with TiO2. Using mesoporous structured MoS2 as ETL, we obtain PSCs with 25.7% (0.08 cm2, certified 25.4%) and 22.4% (1.00 cm2) efficiencies. Under continuous illumination, our cell remains stable for more than 2,000 h, demonstrating improved photostability with respect to TiO2.

EFFECTS OF TEMPERATURE AND STRAIN AMPLITUDE ON LOW-CYCLE FATIGUE PROPERTIES OF NICKEL-BASED SINGLE-CRYSTAL SUPERALLOY DD419

High-temperature and low-cycle fatigue tests were conducted on a nickel-based single-crystal superalloy DD419 under total strain-controlled conditions at 760 °C and 980 °C. The fatigue properties of the alloy are discussed by analysing the fatigue test data. Fracture morphology and dislocation structure were observed using scanning electron microscopy and transmission electron microscopy. At the same strain amplitude, the results indicate that the plastic deformation of the alloy is larger at 980 °C compared to 760 °C. This leads to a lower fatigue strength and shorter fatigue life, along with more severe damage. The value of the strain amplitude affects the cyclic stress response behaviour of the alloy. Under low strain amplitudes, the cyclic stress response behaviour differs between 760 °C and 980 °C. The hysteresis loop exhibits similar shapes at 760 °C and 980 °C, with an increase in the area as the strain amplitude rises. The fatigue fracture analysis indicates that micropores on the surface are the primary fatigue sources at 760 °C, while oxides on the surface are the main fatigue source at 980 °C, leading to cracking due to multiple sources. Moreover, transmission electron microscopy reveals that the deformation mechanism involving dislocations at 760 °C primarily occurs through plane slip and wave slip, whereas at 980 °C, dislocations mainly move through cross slip and climb.

Hot deformation behavior and dynamic recrystallization mechanism of GH2132 superalloy

In order to study the hot deformation and dynamic recrystallization behavior of annealed GH2132 superalloy, this paper conducted hot compression tests of GH2132 superalloy at different temperatures (950°C–1150°C) and different strain rates (0.01/s–10/s) using Thermocmaster Z thermal simulation testing machine, and made an in-depth analysis of recrystallization behavior via electron backscattered diffraction (EBSD). The results indicate that the flow stresses of GH2132 alloy first increase and then decrease at high temperature, among which the curves present a more obvious flow softening at 10/s. Continuous dynamic recrystallization (CDRX) is dominant at high temperature and low strain rate, while discontinuous dynamic recrystallization (DDRX) plays the major role at low temperature and high strain rate. The type of recrystallization has a significant impact on the formation and volume fraction of twinning. In addition, high-temperature constitutive model, hot processing map, and an unified dynamic recrystallization kinetic model of GH2132 superalloy were established. Thus, the optimal range of hot working parameters was obtained. The research results provide guidance for determining the hot working process window of GH2132 superalloy.

Effect of Plate Screw Configuration on Construct Stiffness and Plate Strain in a Synthetic Short Fragment Small Gap Fracture Model Stabilized with a 12-Hole 3.5-mm Locking Compression Plate.

The aim of the study was to determine the effect of a short and long working length screw configuration on construct stiffness and plate strain in a synthetic, short fragment, small gap fracture model stabilized with a 12-hole 3.5-mm locking compression plate (LCP). Six replicates of short and long working length constructs on a short fragment, small gap fracture model underwent four-point bending. Construct stiffness and plate strain were compared across working length and along the plate. With the LCP on the compression surface (compression bending), the short working length had a significantly higher construct stiffness and lower plate strain than the long working length. Conversely, with the LCP on the tension surface (tension bending), transcortical contact between 150 and 155 N induced load sharing at the fracture gap, which significantly increased construct stiffness and decreased plate strain in the long working length. At 100 N (precontact), the short working length had a significantly higher construct stiffness and lower plate strain than the long working length, comparable with our compressing bending results. In compression bending, and before transcortical contact occurred in tension bending, the short working length had a significantly higher construct stiffness and lower plate strain than the long working length. Load sharing due to transcortical contact observed in our model in tension bending will vary with fracture gap, working length, and loading condition. These results must be interpreted with caution when considering clinical relevance or potential in vivo biomechanical advantages.

In-situ synchrotron high energy X-ray diffraction study on the compressive creep behavior of an extruded Ti-45Al-8Nb-0.2C alloy

Wrought high Nb containing (high Nb-TiAl) alloys are potential materials for low pressure turbine blades in aero-engines. The performance and microstructure evolution under high temperature creep condition is of importance to the service stability of these materials. In this study, the internal strain and FWHM evolution of an extruded TNB-based high Nb-TiAl alloy during compressive creep are characterized by in-situ high energy X-ray diffraction (HEXRD) technique for the first time. The compressive creep test was conducted under a constant load of 300 MPa at 900 °C for 10 h in vacuum. The final creep strain is approximately 1.72 %. The microstructure and phase constitution after creep shows little difference from that before creep. Lattice strain analysis shows that γ phase is plastically deformed while the α2 phase deforms elastically due to the low creep strain. The lattice strain of α2 grains is dependent upon the deformation of surrounding γ grains. Creep induces dynamic recovery, exerting a softening effect. A high number of dislocations are visible in the γ lamellae while almost no dislocations exist within the α2 lamellae. α2 lamellae are partially decomposed and refined via the α2→γ transformation.

IMMISCIBLE POLYMER–FILLER SYSTEMS FOR TUNABLE MECHANICAL PROPERTIES

ABSTRACT A model system consisting of a 50/50 immiscible mixture of polyethylene glycol (PEG) and polytetrahydrofuran (PTHF), with covalently bound nano silica–reinforcing particles, was used to investigate how the distribution of particles affects viscoelastic properties. The rubbery polymers were generated by chain extending from their respective oligomers through hydroxyl end groups with 1,6-diisocyanato hexane. The viscosity of the resulting PEG and PTHF polymers was 32 and 1000 Pa-s, respectively. Setting the overall SiO2 concentration to 10 phr, we explored three different silica distributions: (1) all-in-PEG, 20 phr in PEG and neat PTHF; (2) uniform, 10 phr in both PEG and PTHF; and (3) all-in-PTHF, neat PEG and 20 phr in PTHF. When compared with the uniform system, the storage and loss shear moduli and the viscosity of the all-in-PTHF system showed a 20-fold increase of the stiffness at low strain, yet nearly the same viscosity at high strain. Similarly, the storage and loss moduli of all-in-PEG mixtures were roughly 1/10 that of the uniform system. The surprisingly high modulus and high viscosity of the all-in-PTHF system can be understood as the entire PTHF regions themselves becoming solid filler.

Bonding mechanism of TC4 titanium alloy/T2 copper vacuum diffusion bonded joint with nickel as transition interlayer

Vacuum diffusion bonding of TC4 titanium alloy (TC4) to T2 copper (T2) using nickel foil as transition interlayer was explored. Ti3Ni, Ti2Ni, TiNi, AlNi2Ti and TiNi3 phases arose at the TC4/Ni bonded interface, and Cu-Ni solid solution appeared in the Ni/T2 interface. Thereinto, AlNi2Ti was a kind of discontinuous nano precipitated phase, which distributed between TiNi and TiNi3 phases. The crystallographic orientations of Ti2Ni, TiNi, AlNi2Ti and TiNi3 phases were (201), (020), (11¯1) and (031), respectively. The interplanar spacing of (031), (11¯1) and (020) was correspondingly d(031) = 0.144 nm, d11¯1 = 0.275 nm and d(020) = 0.137 nm. The lattice mismatch between TiNi3 and TiNi was calculated to be 2.5 %, with low strain energy. The order of effective formation enthalpies for TiNi3, TiNi and Ti2Ni phases formed between titanium and nickel was ∆H′NiTi2 > ∆H′NiTi > ∆H′Ni3Ti. The growth activation energy of TiNi3, TiNi and Ti2Ni phases was correspondingly 35.8 kJ/mol, 180.6 kJ/mol and 347.1 kJ/mol. When welding at 880 °C for 60 min, the highest shear strength of the joints could achieve 150 MPa. The joints fractured along the Ni/T2 interface, the fracture surface of joint was composed of elongated dimples and cellular pits, presenting a shear ductile fracture mode. FCC-Cu, FCC-Ni and (Ni, Cu)ss phases were detected on TC4 and T2 fracture surfaces by XRD. The interdiffusion coefficient ratio of (Ni in Cu)/(Cu in Ni) and (Ni in Ti)/(Ti in Ni) decreased gradually with increasing temperature.

High-temperature hot deformation behavior and processing map of Ti-22Al-25Nb alloy

The high-temperature deformation behavior of the Ti-22Al-25Nb alloy was investigated by conducting hot compression experiments. A constitutive equation predicting the flow behavior of the Ti-22Al-25Nb alloy was established by analyzing its stress–strain curves. The strain-compensated constitutive equation effectively predicted the flow stress of the alloy with a correlation coefficient of 0.992 between the measured and predicted values and an average absolute relative error of 6.548 %. A hot processing map was obtained based on a dynamic material model. It demonstrated that the optimal processing region corresponded to the deformation temperatures of 1273–1353 K and strain rates of 0.001–0.01 s−1. Using electron backscatter diffraction data, thermal deformation mechanisms were elucidated under different deformation conditions within the safe region. The obtained results revealed that under the low temperature (T ≤ 1323 K) and low strain rate (ε̇ ≤ 1 s−1) conditions, continuous dynamic recrystallization and dynamic recovery (DRV) were the main thermal deformation mechanisms. Under the medium-to-high temperature (T ≥ 1323 K) and low strain rate (ε̇ ≤ 1 s−1) conditions, the main thermal deformation mechanisms were discontinuous dynamic recrystallization and DRV. At high strain rates (ε̇ ≥ 1 s−1), the primary thermaldeformation mechanism was DRV. The occurrence of discontinuous yielding in the alloy at high strain rates was related to the proliferation of mobile dislocations at grain boundaries.

Strain softening of carbon black/isoprene rubber/nitrile rubber ternary vulcanizate nanocomposites

The influence of filler selective distribution on the strain softening behaviors (Payne and Mullins effects) has been seldom studied for ternary rubber nanocomposites. Herein selected distribution of carbon black (CB) in the CB/isoprene rubber (IR)/nitrile rubber (NBR) nanocomposites is regulated simply by varying compounding sequences. The location of CB does not significantly influence the Payne effects and slightly influences the Mullins effect in the first cyclic tension run. However, it influences the Mullins effect of the demullinized nanocomposites (in the third deformation runs) markedly, and the CB concentration in the crystallizable IR phase tends to improve damping ratio at high strains. The influence of CB selective localization on the Mullins effect involves the strain-induced crystallization of the IR phase. For tensile performances, the CB concentration in the IR and NBR phases tends to improve strain hardening at high strains and stress at low strains, respectively. This work provides a way to tailor the strain softening and tensile behaviors of the ternary rubber nanocomposites by control of the filler selective dispersion.

Interplay between deformation and fracture mechanism in gradient nanostructured austenitic stainless steel

The plastic deformation parameters are crucial for the grain size of gradient nanostructured (GNS) materials, and the multiscale grain structure within the GNS layer has a significant impact on fracture behavior. In this study, the detailed depth-dependent microstructures of GNS310S stainless steel fabricated by surface mechanical rolling treatment (SMRT) were investigated, and the relationship between the geometrically necessary dislocation (GND) density and the strain gradient was established through the local misorientation obtained by electron backscatter diffraction. The critical deformation parameters (strain gradient, shear strain, and strain rate) of SMRT-induced grain refinement at different scales were quantitatively evaluated. The tensile results show the yield strength and tensile strength of GNS310S are improved by 103 % and 23.1 % respectively compared to CG310S. Additionally, we elucidate the underlying tensile fracture mechanism of GNS310S stainless steel through detailed microstructural analysis. Due to the poor ductility of the near-equiaxed nanograins, cracking occurred on the surface of the SMRT specimen at low strain during the tensile testing. These cracks evolved into competitive shear offsets and multi-cracks with increased strain on the specimen surface, eventually leading to a hybrid fracture mode. In contrast, the subsurface nanotwinned lamellae layer displayed good ductility during tension, which can accommodate the deformation through lamellae widening and forming secondary twinning. This nanotwinned lamellae layer can suppress the inward propagation of surface cracks when the strain was not large. This work provides new insights into the fabricating parameters of the GNS stainless steel, as well as the deformation and fracture mechanisms.

Extension of the GISSMO fracture model for thin-walled structures under combined tensile and bending loads

Ductile fracture prediction for thin-walled structures requires computationally efficient simulation tools able to approximately represent the key effects that occur on the sub-thickness scale. Unfortunately, classical shell elements, typically used to model deformation and failure of thin components, are inherently in a state of plane stress and therefore unable to capture the through-thickness stress distribution. This is consequential considering recent studies that demonstrated the differences between fracture in bending vs. in-plane tension. A laterally constrained thin metal plate under in-plane tension is likely to fracture under significantly lower plastic strain than the same plate under bending (with fracture initiating on the tensile side), even though both these conditions are examples of plane strain tension. Under in-plane tension fracture is preceded by a through-thickness neck, and therefore higher stress triaxiality than in the case of plane strain bending, where necking is absent. To account for these differences, we propose an extension of the GISSMO model, which relies on a simple fracture criterion based on stress-dependent fracture strain defined by the user (i.e. fracture locus). The fracture strain is typically determined experimentally using a combination of in-plane tensile tests under varying degree of lateral constraint and shear tests. The proposed extension involves defining a separate fracture locus for bending, also determined experimentally using bending tests. Fracture occurs when the equivalent plastic strain reaches its critical level represented by interpolation between the two bounding cases, i.e. bending and in-plane tension, with a bending index Ω used as an interpolation parameter.

Detection of Left Atrial Remodeling by Three-Dimensional Echocardiography in Symptomatic Patients Known to Had Non-Obstructive Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is one of the most prevalent inherited disorders and a common cause of sudden heart death. Left atrial (LA) dilatation frequently occurs in patients with HCM as a result of impaired left ventricular (LV) relaxation or associated involvement of LA myocardium in HCM. We enrolled 170 patients known to had HCM (non-obstructive type) and 30 healthy subjects (control group). All of them underwent two-dimensional (2D) echocardiography to measure LV dimensions, function, LA dimension, LA deformations, pulmonary artery pressure (PAP) and LV global longitudinal strain (LVGLS). LA volumes and mechanics were also measured by three-dimensional (3D) echocardiography. By 2D echocardiography, patient group revealed significantly lower all LA functions vs. control group including reservoir (26 ± 4 vs. 43 ± 3, P < 0.001), conduit (-14 ± 2 vs. -25 ± 2, P < 0.001), and booster pump functions (-12 ± 2 vs. -18 ± 1, P < 0.001). PAP was significantly higher in patient group (42 ± 7 vs. 27 ± 4 in control group). LVGLS was significantly lower in patient group (-15±1.4% vs. -23±2% in control group). Using 3D speckle tracking echocardiography (STE), there were a significantly higher indexed maximum LA volume (Vmax indexed) (43.5 ± 5.6 vs. 28.7 ± 3.7, P < 0.001), but significantly lower left atrial strain at reservoir function (LASr) (24 ± 4 vs. 41 ± 3, P < 0.001), left atrial strain at conduit function (LAScd) (-13 ± 2 vs. -24 ± 2, P < 0.001), and left atrial strain at contractile function (LASct) (-11 ± 2 vs. -18 ± 1, P < 0.001). Three-dimensional transthoracic echocardiography (TTE) is a feasible method for the assessment of LA remodeling, but there is adverse LA remodeling in patients with long-standing non-obstructive HCM including impaired all LA mechanics and with increased septal thickness, there are more diastolic dysfunction and more reduction of LA mechanics.

Automatic Echocardiographic Assessment of Left Atrial Function for Prediction of Low-Voltage Areas in Non-Valvular Atrial Fibrillation.

Left atrial low-voltage areas (LA-LVAs) identified by 3D-electroanatomical mapping are crucial for determining treatment strategies and prognosis in patients with atrial fibrillation (AF). However, convenient and accurate prediction of LA-LVAs remains challenging. This study aimed to assess the viability of utilizing automatically obtained echocardiographic parameters to predict the presence of LA-LVAs in patients with non-valvular atrial fibrillation (NVAF). This retrospective study included 190 NVAF patients who underwent initial catheter ablation. Before ablation, echocardiographic data were obtained, left atrial volume and strain were automatically calculated using advanced software (Dynamic-HeartModel and AutoStrain). Electroanatomic mapping (EAM) was also performed. Results were compared between patients with LA-LVAs ≥5% (LVAs group) and <5% (non-LVAs group). LA-LVAs were observed in 81 patients (42.6%), with a significantly higher incidence in those with persistent AF than paroxysmal AF (55.6% vs 19.3%, P <0.001). Compared with the non-LVAs group, the LVAs group included significantly older patients, lower left ventricular ejection fraction, higher heart rate, and higher E/e' ratio (P <0.05). The LVAs group exhibited higher left atrial volumemax index (LAVimax) and lower left atrial reservoir strain (LASr) (P <0.001). In multivariate analysis, both LAVimax and LASr emerged as independent indicators of LVAs (OR 0.85; 95% CI 0.80-0.90, P<0.001) and (OR 1.15, 95% CI 1.02-1.29, P =0.021). ROC analysis demonstrated good predictive capacity for LA-LVAs, with an AUC of 0.733 (95% CI 0.650-0.794, P <0.001) for LAVimax and 0.839 (95% CI 0.779-0.898, P <0.001) for LASr. Automatic assessment of LAVimax and LASr presents a promising non-invasive modality for predicting the presence of LA-LVAs and evaluating significant atrial remodeling in NVAF patients. This approach holds potential for aiding in risk stratification and treatment decision-making, ultimately improving clinical outcomes in patients.

Assessing design-induced elasticity of 3D printed auxetic scaffolds for tissue engineering applications

Auxetic scaffolds fabricated via additive manufacturing can enable cyclic mechanical stimulation to promote the biomechanical functionalization of engineered tissues. Typical designs of additively manufactured scaffolds used in tissue engineering literature (e.g., 0/90˚ strand laydown) are not amenable to cyclic loading due to their rigidity, which is in part due to the high stiffness of biopolymers such as polycaprolactone (PCL). Auxetic scaffolds can help overcome this due to their design-induced elasticity while recapitulating negative Poisson’s ratios seen in various natural tissues. In this study, we investigated the effects of auxetic design patterns and unit cell sizes on the mechanical properties of 3D bioplotted PCL scaffolds. First, we assessed the monotonic tensile properties of two auxetic patterns – re-entrant honeycomb and missing rib (unit cell = 3 × 3 mm2 for both) – in comparison to a uniaxial control (0/0˚ strand laydown) using finite element analysis (FEA) and experimental design (n = 3/group). The results showed that the scaffold design significantly impacted scaffold elasticity (p < 0.05), with the missing rib auxetic design demonstrating significantly higher yield strain (48.2 %) compared to the re-entrant honeycomb design (11.0 %) and the control (4.8 %). The missing rib design also possessed significantly lower elastic modulus and tensile strength (11.5 MPa/g and 10 MPa/g, respectively) compared to the re-entrant honeycomb (58 MPa/g and 35.7 MPa/g, respectively) (p < 0.05). For the missing rib design, we further investigated the effect of unit cell size (2 × 2, 3 × 2, 3 × 3 mm2) on the mechanical properties. Both 3 × 2 and 3 × 3 mm2 unit cell scaffolds (n = 3/group) possessed similar mechanical properties whereas the 2 × 2 mm2 unit cell scaffolds possessed significantly lower yield strain and higher elastic modulus and tensile strength (p < 0.05). The missing rib auxetic scaffolds were also tested under tensile cyclic loading for up to 6000 cycles at 10 % of maximum strain at 0.5 Hz. The 2 × 2 mm2 unit cell scaffolds degraded significantly faster than the other two groups. Overall, the 3 × 2 mm2 unit cell scaffolds performed better under cyclic loading in terms of maintaining their tensile strength. Finally, biocompatibility testing of the missing rib 3 × 2 mm2 unit cell scaffolds demonstrated their ability to support the adhesion and viability of fibroblast cells. In future, this knowledge will be leveraged to engineer scaffolds for connective tissues such as tendons and cardiac muscle.

Low-temperature sintering BCZT-Dy ceramics with low strain hysteresis for actuator application

Ba(Cu0.5W0.5)O3 (BCuW)-doped [(Ba0.85Ca0.15)1-xDyx](Zr0.1Ti0.9)O3 (BCZT-xDy, x = 0.001, 0.03) ceramics were prepared by conventional ceramic processing via low-temperature sintering technique. Rather pure perovskite structure and densified morphology with irregular nearly spherical-shape grains are achieved in all ceramics due to liquid-phase sintering. All BCuW-doped BCZT-xDy ceramics present apparent dielectric frequency dispersion and relaxor ferroelectric characteristic due to ion substitution and adding BCuW. The ceramics prepared at optimized sintering temperatures have rather large strain and small strain hysteresis, showing prospect application in piezoelectric high-precision actuators.