Electrospun Poly L-Lactic Acid Nanofiber Webs Presenting Enhanced Piezoelectric Properties.

There has been extensive research on electrospun ferroelectric nanoparticle-doped poly L-lactic acid (PLA) nanofiber web piezoelectric devices. In this study, BaTiO3 nanoparticles (BTNPs) were incorporated into the PLA to enhance the piezoelectric properties. The composite nanofiber webs were characterized using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The piezoelectric behavior was analyzed by measuring the peak-to-peak output voltage (Vp-p) of the samples. The sensors fabricated from the PLA/BTNP nanofiber webs exhibited higher Vp-p values than the conventional electrospun PLA sensors. Furthermore, the corona-poled PLA/BTNP nanofiber web sensors exhibited even higher Vp-p values than the non-corona-poled sensors. Lastly, the effect of stacking nanofiber webs in terms of enhancing the sensor performance was also evaluated.

Efficacy of dapagliflozin in improving arrhythmia-related outcomes after ablation for atrial fibrillation: a retrospective single-center study.

BACKGROUND: Atrial fibrillation (AF) is a widespread type of sustained arrhythmia that poses significant health risks. Catheter ablation is the preferred treatment; however, arrhythmia recurrence remains challenging. Sodium-glucose co-transporter 2 inhibitors, particularly dapagliflozin (DAPA), have exhibited cardiovascular benefits. However, to date, the influence of these inhibitors on AF post-ablation remains unclear. METHODS: We analyzed the records of 272 patients who underwent catheter ablation for AF from January 2018 to December 2022. Patients were divided into the control (n = 199) and DAPA (n = 73) groups based on DAPA prescription post-ablation. The primary outcome was total atrial arrhythmia recurrence after a 3-month blanking period. RESULTS: The mean age was 72.19 ± 5.45 years; 86.8% of the patients were men. At 18 months post-ablation, 36.2% and 9.5% of the patients in the control and DAPA groups, respectively, reported atrial arrhythmia. Multivariate analysis revealed that DAPA use was associated with a significantly reduced risk of arrhythmia recurrence (adjusted hazard ratio [aHR]: 0.15, 95% confidence interval [CI]: 0.07-0.32, p < 0.001). After propensity score-matching (PSM) in 65 pairs, arrhythmia recurrence was lower in the DAPA group compared with the control (8.3% versus 30.8%, aHR: 0.17, 95% CI: 0.06-0.51, p = 0.002). Freedom from total arrhythmia recurrence was significantly higher in the DAPA group compared with the control group in both the overall and PSM population (log-rank test p < 0.01). CONCLUSION: DAPA administration post-ablation was associated with significantly reduced atrial arrhythmia recurrence rates, indicating its potential as an adjunct therapy for enhancing the success of AF ablation.

Physical Unclonable Functions Employing Circularly Polarized Light Emission from Nematic Liquid Crystal Ordering Directed by Helical Nanofilaments.

This study proposes the use of physical unclonable functions employing circularly polarized light emission (CPLE) from nematic liquid crystal (NLC) ordering directed by helical nanofilaments in a mixed system composed of a calamitic NLC mixture and a bent-core molecule. To achieve this, an intrinsically nonemissive NLC is blended with a high concentration of a luminescent rod-like dye, which is miscible up to 10 wt % in the calamitic NLC without a significant decrease in the degree of alignment. The luminescence dissymmetry factor of CPLEs in the mixed system strongly depends on the degree of alignment of the dye-doped NLCs. Furthermore, the mixed system prepared in this study exhibits two randomly generated chiral domains with CPLEs of opposite signs. These chiral domains are characterized not only by their CPLE performances but also by their ability to generate random patterns up to several millimeters, making them promising candidates for high-performance secure authentication applications.

Circularly Polarized Light Emission from Nonchiral Perovskites Incorporated into Nanoporous Cholesteric Polymer Templates.

Chiral perovskites have garnered significant attention, owing to their chiroptical properties and emerging applications. Current fabrication methods often involve complex chemical synthesis routes. Herein, an alternative approach for introducing chirality into nonchiral hybrid organic-inorganic perovskites (HOIPs) using nanotemplates composed of cholesteric polymeric networks is proposed. This method eliminates the need for additional molecular design. In this process, HOIP precursors are incorporated into a porous cholesteric polymer film, and two-dimensional (2D) HOIPs grow inside the nanopores. Circularly polarized light emission (CPLE) was observed even though the selective reflection band of the cholesteric polymer films containing a representative HOIP deviated from the emission wavelength of the 2D HOIP. This effect was confirmed by the induced circular dichroism (CD) observed in the absorbance band of the HOIP. The observed CPLE and CD are attributed to the chirality induced by the template in the originally nonchiral 2D HOIP. Additionally, the developed 2D HOIP exhibited a long exciton lifetime and good stability under harsh conditions. These findings provide valuable insights into the development and design of innovative optoelectronic materials.

Effect of Nematogen Doping in Bent-Core Molecular Systems with a Helical Nanofilament and Dark Conglomerate.

Two types of binary mixtures were prepared. One consisted of a calamitic nematogen and bent-core molecule with a helical nanofilament, whereas the other contained a calamitic nematogen and bent-core molecule with a dark conglomerate. The chiroptical features of these two mixtures were investigated using polarized optical microscopy and circular dichroism. In addition, X-ray diffraction analysis was performed on the two binary mixtures. The chiroptical features of the two mixtures were remarkably different. One mixture showed enhanced chiroptical features, whereas the other did not show chiroptical features. This method may help in distinguishing between helical nanofilaments and dark conglomerates which originate from bent-core molecular systems.

Multi-Threaded Sound Propagation Algorithm to Improve Performance on Mobile Devices.

We propose a multi-threaded algorithm that can improve the performance of geometric acoustic (GA)-based sound propagation algorithms in mobile devices. In general, sound propagation algorithms require high computational cost because they perform based on ray tracing algorithms. For this reason, it is difficult to operate sound propagation algorithms in mobile environments. To solve this problem, we processed the early reflection and late reverberation steps in parallel and verified the performance in four scenes based on eight sound sources. The experimental results showed that the performance of the proposed method was on average 1.77 times better than that of the single-threaded method, demonstrating that our algorithm can improve the performance of mobile devices.

Ultra-Wide Band Gap Ga2O3-on-SiC MOSFETs.

Ultra-wide band gap semiconductor devices based on ß-phase gallium oxide (Ga2O3) offer the potential to achieve higher switching performance and efficiency and lower manufacturing cost than that of today's wide band gap power electronics. However, the most critical challenge to the commercialization of Ga2O3 electronics is overheating, which impacts the device performance and reliability. We fabricated a Ga2O3/4H-SiC composite wafer using a fusion-bonding method. A low-temperature (≤600 °C) epitaxy and device processing scheme was developed to fabricate MOSFETs on the composite wafer. The low-temperature-grown epitaxial Ga2O3 devices deliver high thermal performance (56% reduction in channel temperature) and a power figure of merit of (∼300 MW/cm2), which is the highest among heterogeneously integrated Ga2O3 devices reported to date. Simulations calibrated based on thermal characterization results of the Ga2O3-on-SiC MOSFET reveal that a Ga2O3/diamond composite wafer with a reduced Ga2O3 thickness (∼1 µm) and a thinner bonding interlayer (<10 nm) can reduce the device thermal impedance to a level lower than that of today's GaN-on-SiC power switches.

Chiroptical Performances in Self-Assembled Hierarchical Nanosegregated Chiral Intermediate Phases Composed of Two Different Achiral Bent-Core Molecules.

In this paper, chiral intermediate phases composed of two achiral molecules are fabricated by utilizing nanophase separation and molecular hierarchical self-organization. An achiral bent-core guest molecule, exhibiting a calamitic nematic and a dark conglomerate phase according to the temperature, is mixed with another achiral bent-core host molecule possessing a helical nanofilament to separate the phases between them. Two nanosegregated phases are identified, and considerable chiroptical changes, such as circular dichroism and circularly polarized luminescence, are detected at the transition temperatures between the different nanophase-separated states. The nanosegregated chiral phase-wherein the helical nanofilament and dark conglomerate phases are phase-separated-exhibits the highest chiroptical intensities. The luminescence dissymmetry factor, |glum|, in this phase is amplified by an order of magnitude compared with that of another nanosegregated phase, wherein the helical nanofilament and nematic phases are phase-separated.

Chiroptical Characteristics of Nanosegregated Phases in Binary Mixture Consisting of Achiral Bent-Core Molecule and Bent-Core Base Main-Chain Polymer.

In this paper, a binary mixture system consisting of an achiral bent-core molecule and a bent-core base main-chain polymer is described. The mixture exhibits an intriguing nanosegregated phase generated by the phase separation of the helical nanofilament B4 phase (originating from the bent-core molecule) and the dark conglomerate phase (originating from the bent-core base main-chain polymer). This nanosegregated phase was identified using polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction analysis. In this nanosegregated phase, the enantiomeric domains grew to a few millimeters and a giant circular dichroism was observed. The structural chirality of the helical nanofilament B4 phase affected the conformation of the bent-core base main-chain polymer embedded within the helical nanofilament networks of bent-core molecules.

Study of the Relationship between Haze Performance and Fractal Dimension in Micro-Sized Segregated Liquid Crystals Embedded in a Polymer Matrix Consisting of a Thiol-ene Prepolymer and a Multi-Functional Acrylate.

Micro-sized segregated liquid crystals (MSLCs) surrounded by a polymer medium can be used for haze film applications. When incident light passes through the MSLC film, the microsized particles act as light scattering centers. In this study, the results of the addition of a multi-functional acrylate to a commercial thiol-ene prepolymer system, as well as the morphology of (LC) droplets, fractal dimension (D), and the optical haze performance of the micro-sized segregated LCs formed by UV-initiated photopolymerization, are reported. With increasing fraction of the multi-functional acrylate within the host polymer matrix, the small scattering centers (LC droplets) also increase, giving rise to a large optical haze in the prepared film. The optical haze can be characterized by the D of the associated LC droplet morphology in the films. The optical haze and D exhibit a strong correlation; thus, a qualitative prediction of the optical haze is possible via geometric fractal analysis.

Control of the Induced Handedness of Helical Nanofilaments Employing Cholesteric Liquid Crystal Fields.

In this paper, a simple and powerful method to control the induced handedness of helical nanofilaments (HNFs) is presented. The nanofilaments are formed by achiral bent-core liquid crystal molecules employing a cholesteric liquid crystal field obtained by doping a rod-like nematogen with a chiral dopant. Homochiral helical nanofilaments are formed in the nanophase-separated helical nanofilament/cholesteric phase from a mixture with a cholesteric phase. This cholesteric phase forms at a temperature higher than the temperature at which the helical nanofilament in a bent-core molecule appears. Under such conditions, the cholesteric liquid crystal field acts as a driving force in the nucleation of HNFs, realizing a perfectly homochiral domain consisting of identical helical nanofilament handedness.

Ga2O3-on-SiC Composite Wafer for Thermal Management of Ultrawide Bandgap Electronics.

ß-phase gallium oxide (Ga2O3) is an emerging ultrawide bandgap (UWBG) semiconductor (EG ∼ 4.8 eV), which promises generational improvements in the performance and manufacturing cost over today's commercial wide bandgap power electronics based on GaN and SiC. However, overheating has been identified as a major bottleneck to the performance and commercialization of Ga2O3 device technologies. In this work, a novel Ga2O3/4H-SiC composite wafer with high heat transfer performance and an epi-ready surface finish has been developed using a fusion-bonding method. By taking advantage of low-temperature metalorganic vapor phase epitaxy, a Ga2O3 epitaxial layer was successfully grown on the composite wafer while maintaining the structural integrity of the composite wafer without causing interface damage. An atomically smooth homoepitaxial film with a room-temperature Hall mobility of ∼94 cm2/Vs and a volume charge of ∼3 × 1017 cm-3 was achieved at a growth temperature of 600 °C. Phonon transport across the Ga2O3/4H-SiC interface has been studied using frequency-domain thermoreflectance and a differential steady-state thermoreflectance approach. Scanning transmission electron microscopy analysis suggests that phonon transport across the Ga2O3/4H-SiC interface is dominated by the thickness of the SiNx bonding layer and an unintentionally formed SiOx interlayer. Extrinsic effects that impact the thermal conductivity of the 6.5 µm thick Ga2O3 layer were studied via time-domain thermoreflectance. Thermal simulation was performed to estimate the improvement of the thermal performance of a hypothetical single-finger Ga2O3 metal-semiconductor field-effect transistor fabricated on the composite substrate. This novel power transistor topology resulted in a ∼4.3× reduction in the junction-to-package device thermal resistance. Furthermore, an even more pronounced cooling effect is demonstrated when the composite wafer is implemented into the device design of practical multifinger devices. These innovations in device-level thermal management give promise to the full exploitation of the promising benefits of the UWBG material, which will lead to significant improvements in the power density and efficiency of power electronics over current state-of-the-art commercial devices.

Thermal Conductivity of ß-Phase Ga2O3 and (AlxGa1-x)2O3 Heteroepitaxial Thin Films.

Heteroepitaxy of ß-phase gallium oxide (ß-Ga2O3) thin films on foreign substrates shows promise for the development of next-generation deep ultraviolet solar blind photodetectors and power electronic devices. In this work, the influences of the film thickness and crystallinity on the thermal conductivity of (2̅01)-oriented ß-Ga2O3 heteroepitaxial thin films were investigated. Unintentionally doped ß-Ga2O3 thin films were grown on c-plane sapphire substrates with off-axis angles of 0° and 6° toward ⟨112̅0⟩ via metal-organic vapor phase epitaxy (MOVPE) and low-pressure chemical vapor deposition. The surface morphology and crystal quality of the ß-Ga2O3 thin films were characterized using scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The thermal conductivities of the ß-Ga2O3 films were measured via time-domain thermoreflectance. The interface quality was studied using scanning transmission electron microscopy. The measured thermal conductivities of the submicron-thick ß-Ga2O3 thin films were relatively low as compared to the intrinsic bulk value. The measured thin film thermal conductivities were compared with the Debye-Callaway model incorporating phononic parameters derived from first-principles calculations. The comparison suggests that the reduction in the thin film thermal conductivity can be partially attributed to the enhanced phonon-boundary scattering when the film thickness decreases. They were found to be a strong function of not only the layer thickness but also the film quality, resulting from growth on substrates with different offcut angles. Growth of ß-Ga2O3 films on 6° offcut sapphire substrates was found to result in higher crystallinity and thermal conductivity than films grown on on-axis c-plane sapphire. However, the ß-Ga2O3 films grown on 6° offcut sapphire exhibit a lower thermal boundary conductance at the ß-Ga2O3/sapphire heterointerface. In addition, the thermal conductivity of MOVPE-grown (2̅01)-oriented ß-(AlxGa1-x)2O3 thin films with Al compositions ranging from 2% to 43% was characterized. Because of phonon-alloy disorder scattering, the ß-(AlxGa1-x)2O3 films exhibit lower thermal conductivities (2.8-4.7 W/m·K) than the ß-Ga2O3 thin films. The dominance of the alloy disorder scattering in ß-(AlxGa1-x)2O3 is further evidenced by the weak temperature dependence of the thermal conductivity. This work provides fundamental insight into the physical interactions that govern phonon transport within heteroepitaxially grown ß-phase Ga2O3 and (AlxGa1-x)2O3 thin films and lays the groundwork for the thermal modeling and design of ß-Ga2O3 electronic and optoelectronic devices.

Thermal Conductivity of Aluminum Scandium Nitride for 5G Mobile Applications and Beyond.

Radio frequency (RF) microelectromechanical systems (MEMS) based on Al1-xScxN are replacing AlN-based devices because of their higher achievable bandwidths, suitable for the fifth-generation (5G) mobile network. However, overheating of Al1-xScxN film bulk acoustic resonators (FBARs) used in RF MEMS filters limits power handling and thus the phone's ability to operate in an increasingly congested RF environment while maintaining its maximum data transmission rate. In this work, the ramifications of tailoring of the piezoelectric response and microstructure of Al1-xScxN films on the thermal transport have been studied. The thermal conductivity of Al1-xScxN films (3-8 W m-1 K-1) grown by reactive sputter deposition was found to be orders of magnitude lower than that for c-axis-textured AlN films due to alloying effects. The film thickness dependence of the thermal conductivity suggests that higher frequency FBAR structures may suffer from limited power handling due to exacerbated overheating concerns. The reduction of the abnormally oriented grain (AOG) density was found to have a modest effect on the measured thermal conductivity. However, the use of low AOG density films resulted in lower insertion loss and thus less power dissipated within the resonator, which will lead to an overall enhancement of the device thermal performance.

Prognostic Value of Leg Muscle Strength in Acute Heart Failure Syndrome.

INTRODUCTION: Leg muscle strength (LMS) may be useful as a frailty index in patients with heart failure. However, LMS, until recently, has been indirectly estimated, and its prognostic value in acute heart failure syndrome (AHFS) is unclear. Therefore, we evaluated the prognostic value of direct LMS assessment and its relationship with proinflammatory mediators in patients with AHFS. METHODS: We directly measured LMS at predischarge using a dynamometer in 110 prospectively and consecutively enrolled patients with AHFS (75 male; 60 ± 14 yr; mean ejection fraction, 29.9% ± 14.6%). The primary end point was cardiovascular (CV) events, defined as CV mortality, cardiac transplantation, or rehospitalization due to heart failure aggravation. Patients were divided into impaired and preserved LMS groups according to Contal and O'Quigley's method. RESULTS: CV events occurred in 28 patients (25.5%) (including 5 CV deaths and 6 cardiac transplantations) during follow-up (median, 246 d; range = 11-888 d). Impaired LMS was associated with significantly higher levels of serum monokine induced by gamma interferon and poor clinical outcomes (P < 0.001). Multivariable Cox proportional hazard analysis (controlling for age, sex, body mass index, heart failure type, hemoglobin level, N-terminal pro-b-type natriuretic peptide level, and beta-blocker use) revealed LMS as an independent predictor of CV events (P = 0.017). CONCLUSION: Impaired LMS, which might be used as a marker of frailty, is associated with increased levels of a proinflammatory chemokine and independently predicts clinical outcomes in patients with AHFS. The direct measurement of LMS is simple and feasible and might have important implications for the risk stratification of patients with AHFS.

Preferential Circularly Polarized Luminescence from a Nano-Segregated Liquid Crystalline Phase Using a Polymerized Twisted Nematic Platform.

In this study, a polymerized twisted nematic (TN) network was used as an extrinsic chiral platform to overcome the heterogeneity during spontaneous symmetry breaking in a mixed system comprising an achiral bent-core molecule and rod-like mesogen. The TN platform was prepared by photopolymerizing a reactive mesogen dispersed in a low molecular weight liquid crystal with TN orientation. The use of TN orientation to correct the degeneracy in bent-core molecular systems has been previously reported; however, to the best of our knowledge, this is the first study that uses an extrinsic chiral platform of a polymerized TN network. The heterogeneity in the nano-segregated phase of the achiral mixture was suppressed using the extrinsic TN platform with a twisted angle θ of ≥ |±30°|. When an achiral mixture doped with a luminescent guest molecule was refilled into the extrinsic chiral platform, preferential deracemization with one-handedness occurred, corresponding to the handedness of the TN platform. Therefore, circularly polarized luminescence with a preferential handedness can be achieved using this extrinsic chiral platform.

Inverse Helical Nanofilament Networks Serving as a Chiral Nanotemplate.

Herein, an epoch-making method based on bottom-up templating is proposed for the fabrication of a chiral nanoporous film that provides a chiral environment in which to confine nematic liquid crystals. A helical nanofilamental network of bent-core molecules was utilized as a three-dimensional mold, and thus the fabricated chiral nanoporous film has an inverse nanohelical structure. The presence of a chiral superstructure was confirmed by the observation of circular dichroism signals. Upon refilling this chiral nanoporous film with an achiral nematic liquid crystal, distinct circular dichroism signals appeared due to the transfer of chirality from the inverse helical nanofilaments to the achiral nematic liquid crystal. The circular dichroism signals can be readily modulated by external stimuli, such as the application of heat or an electric field. In addition, by refilling the chiral nanoporous film with a nematic liquid crystal doped with fluorescent dye, it exhibits stimuli-responsive circularly polarized luminescence. The proposed approach has huge potential for practical applications, such as for chiroptical modulators and switches and biological sensors.

High-contrast and reversible polymer thermal regulator by structural phase transition.

In comparison with the advancement of switchable, nonlinear, and active components in electronics, solid-state thermal components for actively controlling heat flow have been extremely rare. We demonstrate a high-contrast and reversible polymer thermal regulator based on the structural phase transition in crystalline polyethylene nanofibers. This structural phase transition represents a dramatic change in morphology from a highly ordered all-trans conformation to a combined trans and gauche conformation with rotational disorder, leading to an abrupt change in phonon transport along the molecular chains. For five nanofiber samples measured here, we observe an average thermal switching ratio of ~8× and maximum switching ratio of ~10×, which occurs in a narrow temperature range of 10 K across the structural phase transition. To the best of our knowledge, the ~10× switching ratio exceeds any reported experimental values for solid-solid and solid-liquid phase transitions of materials. There is no thermal hysteresis observed upon heating/cooling cycles.

Increased frequency of CD4+CD57+ senescent T cells in patients with newly diagnosed acute heart failure: exploring new pathogenic mechanisms with clinical relevance.

Recent animal studies showed T cells have a direct pathogenic role in the development of heart failure (HF). However, which subsets of T cells contribute to human HF pathogenesis and progression remains unclear. We characterized immunologic properties of various subsets of T cells and their clinical implications in human HF. Thirty-eight consecutive patients with newly diagnosed acute HF (21 males, mean age 66 ± 16 years) and 38 healthy control subjects (21 males, mean age 62 ± 12 years) were enrolled. We found that pro-inflammatory mediators, including CRP, IL-6 and IP-10 and the frequencies of CD57+ T cells in the CD4+ T cell population were significantly elevated in patients with acute HF compared to control subjects. A functional analysis of T cells from patients with acute HF revealed that the CD4+CD57+ T cell population exhibited a higher frequency of IFN-γ- and TNF-α- producing cells compared to the CD4+CD57- T cell population. Furthermore, the frequency of CD4+CD57+ T cells at baseline and its elevation at the six-month follow-up were significantly related with the development of cardiovascular (CV) events, which were defined as CV mortality, cardiac transplantation, or rehospitalization due to HF exacerbation. In conclusion, CD4+CD57+ senescent T cells showed more inflammatory features and polyfunctionality and were associated with clinical outcome in patients with acute HF. More detailed study for senescent T cells might offer new opportunities for the prevention and treatment of human HF.

Cardiovascular outcome of breast cancer patients with concomitant radiotherapy and chemotherapy: A 10-year multicenter cohort study.

BACKGROUND: Cancer treatment increases the risk of cardiovascular (CV) events. However, the long-term CV outcome of breast cancer patients who undergo radiotherapy and chemotherapy concomitantly is unknown. This study aimed to determine the incidence and risk factors of CV events among these patients. METHODS: Six hundred sixty consecutive breast cancer patients older than 50 years from November 2005 to September 2015, were enrolled in four university hospitals. The primary endpoint was CV events including CV mortality, myocardial infarction, heart failure, and stroke. CV events occurred in 14 (2.1%) patients during the follow-up period (median, 47.1 months). RESULTS: Left-side irradiation was associated with increased risk of CV events in patients with doxorubicin dose ≥250mg/m2 but not in patients with doxorubicin dose <250mg/m2. On multivariable analysis, concomitant left-side irradiation with doxorubicin dose ≥250mg/m2 and hypertension were independent risk factors for CV events. CONCLUSION: The risk of CV events was further increased with concomitant left-side irradiation and doxorubicin ≥250mg/m2 in breast cancer patients.