Polarization-selective four-wave mixing in a degenerate multi-level system.

This paper describes the first observation of polarization-selective four-wave mixing signals in conventional coupling-probe spectroscopy, specifically, saturation absorption spectroscopy in 85Rb atoms. The four-wave mixing signal is induced by two counter-propagating laser beams in a degenerate multi-level atomic system, involving the F g = 3 → F e = 2 , 3 , and 4 transitions of the 85Rb D2 line. Consequently, the four-wave mixing signals copropagating along the probe beam induce polarization rotation of a linearly polarized probe beam. To distinguish these four-wave mixing signals from the resulting probe beam, we detect the polarization components orthogonal to the polarization direction of the input probe beam, depending on the linear polarization angles between the probe and coupling beams. The experimental findings demonstrate excellent agreement with theoretical results.

Early apixaban administration considering the size of infarction and functional outcome in acute ischemic stroke.

Background and purpose: Atrial fibrillation-related stroke (AF-stroke) is associated with an adverse prognosis, characterized by a high incidence of progression, recurrence, and hemorrhagic transformation. Our study aims to investigate the potential benefits of stratified early administration of apixaban, taking into account infarct size during the acute phase, in order to enhance functional outcomes. Methods: We conducted this study at a tertiary referral stroke center, enrolling acute AF-stroke patients who received apixaban during the acute phase. Infarct size was categorized as small, medium, or large based on diffusion-weighted imaging. Patients were divided into two groups: standard initiation (apixaban initiation based on guidelines, i.e., small: 4 days, medium: 7 days, large: 14 days after stroke) and early initiation (initiation before guideline recommendations) groups. We compared favorable outcomes (modified Rankin scale score ≤ 2) at 3 months post-stroke, stroke progression, early recurrence, and symptomatic hemorrhagic transformation (sHT) between the groups. Results: Out of 299 AF-stroke patients, 170 (56.9%) were in the early initiation group. A favorable outcome was observed in 105 (61.8%) patients in the early initiation group and 62 (48.1%) patients in the standard initiation group (p = 0.019). Stroke progression or early recurrence occurred less frequently in the early initiation group (4.7% versus 13.2%, p = 0.007). Nevertheless, no difference in sHT was noted between the groups. Early initiation of apixaban was independently associated with favorable outcomes (odds ratio: 2.75, 95% confidence interval: 1.44-5.28, p = 0.002). Conclusion: Our findings suggest that early initiation of apixaban, tailored to infarct size, could serve as a viable strategy to enhance functional outcomes. This approach may potentially decrease stroke progression and early recurrence without elevating the risk of sHT.

Softening of PEO-LiTFSI/LLZTO Composite Polymer Electrolytes for Solid-State Batteries under Cyclic Compression.

Composite polymer electrolytes (CPEs) strike an effective balance between ionic conductivity and mechanical flexibility for lithium-ion solid-state batteries. Long-term performance, however, is limited by capacity fading after hundreds of charge and discharge cycles. The causes of performance degradation include multiple contributing factors such as dendrite formation, physicochemical changes in electrolytes, and structural remodeling of porous electrodes. Among the many factors that contribute to performance degradation, the effect of stress specifically on the composite electrolyte is not well understood. This study examines the mechanical changes in a poly(ethylene oxide) electrolyte with bis(trifluoromethane) sulfonimide. Two different sizes of Li6.4La3Zr1.4Ta0.6O12 particles (500 nm and 5 µm) are compared to evaluate the effect of the surface-to-volume ratio of the ion-conducting fillers within the composite. Cyclic compression was applied to mimic stress cycling in the electrolyte, which would be caused by asymmetric volume changes that occur during charging and discharging cycles. The electrolytes exhibited fatigue softening, whereby the compressive modulus gradually decreased with an increase in the number of cycles. When the electrolyte was tested for 500 cycles at 30% compressive strain, the compressive modulus of the electrolyte was reduced to approximately 80% of the modulus before cycling. While the extent of softening was similar regardless of particle size, CPEs with 500 nm particles exhibited a significant reduction in ionic conductivity after cyclic compression (1.4 × 10-7 ± 2.3 × 10-8 vs 1.1 × 10-7 ± 2.0 × 10-8 S/cm, mean ± standard deviation, n = 4), whereas there was no significant change in ionic conductivity for CPEs with 5 µm particles. These observations -performed deliberately in the absence of charge-discharge cycles -show that repetitive mechanical stresses can play a significant role in altering the performance of CPEs, thereby revealing another possible mechanism for performance degradation in all-solid-state batteries.

Ultralow Loading of Ru as a Bifunctional Catalyst for the Oxygen Electrode of Solid Oxide Cells.

The oxygen evolution reaction (OER) is a significant contributor to the cell overpotential in solid oxide electrolyzer cells (SOECs). Although noble metals such as Ru and Ir have been utilized as OER catalysts, their widespread application in SOECs is hindered by their high cost and limited availability. In this study, we present a highly effective approach to enhance air electrode performance and durability by depositing an ultrathin layer of metallic Ru, as thin as ∼7.5 Å, onto (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) using plasma-enhanced atomic layer deposition (PEALD). Our study suggests that the emergence of a perovskite, SrRuO3, resulting from the reaction between PEALD-based Ru and surface-segregated Sr species, plays a crucial role in suppressing Sr segregation and maintaining favorable oxygen desorption kinetics, which ultimately improves the OER durability. Further, the PEALD Ru coating on LSCF also reduces the resistance to the oxygen reduction reaction (ORR), highlighting the bifunctional electrocatalytic activities for reversible fuel cells. When the LSCF electrode of a test cell is decorated with ∼7.5 Å of the Ru overcoat, a current density of 656 mA cm-2 at 1.3 V in electrolysis mode and a peak power density of 803 mW cm-2 in fuel cell mode are demonstrated at 700 °C, corresponding to an enhancement of 49.1 and 31.9%, respectively, compared to the pristine cell.

Schottky Contacts to ZnO-Nanocoated SnSe Powders by Atomic Layer Deposition.

In this study, SnSe powders are nanocoated with ZnO grown by atomic layer deposition (ALD) with different ALD ZnO pulse cycles. Subsequently, the current transport mechanisms of Pt/ZnO-coated SnSe junctions are electrically investigated. A decrease in the current and an increase in the series resistance are observed at 300 K with increasing ZnO pulse cycles (i.e., increasing the thickness of the ZnO layer). The series resistance is similar at 450 K for all samples. The difference in the barrier height for each sample is insignificant, thus indicating that the ZnO coating marginally alters the barrier height at the Pt/SnSe junction. The inhomogeneous Schottky barrier can explain both the forward and reverse bias current conduction. The lowest ideality factor observed for the SnSe sample with ZnO 100 cycles is related to the lowest standard deviation (i.e., the lowest spatial fluctuation of the barrier height). Furthermore, the electrical conductivity is comparable to that of the sample without ZnO coating, thus suggesting that ZnO-coated SnSe by ALD can be considered to improve the thermoelectric device performance.

Dynamic polarization response of polarization-maintaining fibers by periodic thermal cycling method.

We report a periodic thermal cycling method to investigate the dynamic response of the polarization of a laser propagating through polarization-maintaining (PM) optical fiber, driven by periodic weak temperature modulation. Consequently, temperature modulation on the surface of the coating material of the PM fiber was found to cause a continuous periodic change in the polarization state of the output laser without approaching the steady state of the resulting dynamic polarization response. Additionally, the response was found to depend on the temperature-modulation frequency and amplitude. These experimental results are qualitatively in good agreement with that of the simple theoretical model. Our research would be applied not only to the method of measuring properties of a PM optical fiber by utilizing the continuous modulation of the differential refractive index with a wide modulation-frequency range but also to various applications of the dynamic control of the periodic refractive index in materials.

Long-Term Changes in Post-Stroke Depression, Emotional Incontinence, and Anger.

BACKGROUND AND PURPOSE: Long-term changes in post-stroke depression (PSD), post-stroke emotional incontinence (PSEI), and post-stroke anger (PSA) have rarely been studied. METHODS: This is a sub-study of EMOTION, a randomized, placebo-controlled trial, that examined the efficacy of escitalopram on PSD, PSEI, and PSA in patients with stroke. We interviewed patients at the long-term period (LTP) using predefined questionnaires: Montgomery-Åsberg depression rating scale (MADRS) for PSD, modified Kim's criteria for PSEI, and Spielberger trait anger scale for PSA. Additionally, the ENRICHD Social Support Instrument (ESSI) for the social support state and the modified Rankin Scale (mRS) were measured. We investigated the changes in and factors behind PSD, PSEI, and PSA at LTP. RESULTS: A total of 222 patients were included, and the median follow-up duration was 59.5 months (interquartile range, 50 to 70). Compared to the data at 6 months post-stroke, the prevalence of PSEI (11.7% at 6 months, 6.3% at LTP; P=0.05) and mean anger score (21.62, 16.24; P<0.01) decreased, while the prevalence of PSD (35.6%, 44.6%; P=0.03) and mean MADRS (6.16, 8.67; P<0.01) increased at LTP. ESSI was associated with PSD and PSA, but not with PSEI. The effect of the baseline National Institutes of Health Stroke Scale score on PSD decreased over time. The effect of low social support on PSD was greater than that of mRS at LTP. CONCLUSIONS: The prevalence and degree of PSD significantly increased, while those of PSEI and PSA decreased at LTP. PSD in this stage appeared to be more closely associated with a lack of social support than patients' physical disabilities.

MOF-derived Co/Cu-embedded N-doped carbon for trifunctional ORR/OER/HER catalysis in alkaline media.

In this report, we demonstrate a bimetallic Co/Cu-embedded N-doped carbon structure for trifunctional catalysis of oxygen reduction, oxygen evolution and hydrogen evolution reactions in alkaline media. A hybrid catalyst synthesized through a metal-organic framework-based process (M-NC-CoCu) enables an active trifunctional catalysis due to its multi-faceted favorable characteristics. It is believed that a range of catalytically active sites are formed through the approach including well-dispersed tiny CuCo2O4 phases, a high concentration of pyridinic and graphitic N, and Cu-Ox, Cu-Nx and Co-Nx moieties. In addition, a high-surface-area morphology with a high concentration of sp2 bonding, which is beneficial for facilitated electron conduction, further contributes to the performance as an electrocatalyst.

Are Genetic Variants Associated with the Location of Cerebral Arterial Lesions in Stroke Patients?

BACKGROUND: Genetic variants may play a role in determining the location of cerebral atherosclerosis. We aimed to investigate the association between RNF213, MMP2, and genetic polymorphisms linked to vascular tortuosity with the location of cerebral arterial atherosclerosis. METHODS: A prospective case-control study was conducted on patients with ischemic stroke and age- and sex-matched stroke-free controls. The stroke patients were categorized into those with intracranial artery atherosclerosis (ICAS), extracranial artery atherosclerosis (ECAS), and small vessel occlusion (SVO). Six single nucleotide polymorphisms (SNPs) including rs2118181 (FBN1), rs2179357 (SLC2A10), rs1036095 (TGFBR2), rs243865 (MMP2), rs1800470 (TGFB1), and rs112735431 (RNF213) were analyzed with the TaqMan Genotyping Assay, and the distribution of genotypes across groups was compared. RESULTS: None of the 6 SNPs were associated with stroke on comparing the 449 stroke patients (71 with ECAS, 169 with ICAS, and 209 with SVO) to the 447 controls. In the subgroup analysis, the adjusted odds ratios (aORs) for age and sex indicated a significant association between rs112735431 and ICAS in the allele comparison analysis and in the additive and dominant model analyses. rs112735431 was associated with anterior circulation involvement and increased burden of cerebral atherosclerosis. rs2179357 was significantly associated with ICAS in the recessive model analysis, and rs1800470 was significantly associated with ECAS in the recessive model analysis when compared to controls. CONCLUSION: rs112735431 was associated with ICAS and increased atherosclerosis burden in Korean stroke patients. Further studies are needed to elucidate the role of rs112735431 and to confirm the association of rs2179357 and rs1800470 with cerebral atherosclerosis.

Post-stroke cognitive impairment as an independent predictor of ischemic stroke recurrence: PICASSO sub-study.

INTRODUCTION: To devise appropriate preventive strategies after stroke, knowledge of the association between post-stroke cognitive impairment (PSCI) and prognosis of stroke patients is important. We investigated the association between PSCI and the vascular outcomes in patients with ischemic stroke with best medical care considering their risk factors and adherence to medications. METHODS: Of the 1534 ischemic stroke patients who randomly assigned to aspirin or cilostazol treatment with best medical therapy by the PICASSO (PreventIon of CArdiovascular events in iSchemic Stroke patients with high risk of cerebral hemOrrhage) trial, 1240 with baseline mini-mental state examination (MMSE) scores were analysed retrospectively. The patients were classified into three groups based on MMSE scores. Recurrence of ischemic stroke, stroke of any type and composite of major vascular events were compared among them. RESULTS: Of the 1240 patients, 376 had MMSE scores of 28-30 (highest tertile), 419 had scores of 24-27 (middle tertile) and 445 had scores of 0-23 (lowest tertile). The average time from stroke onset to MMSE examination was 31.8 days. By trend analysis, lower tertile of MMSE score was significantly associated with recurrent ischemic stroke (p = 0.0017), stroke of any type (p = 0.0053) and composite vascular outcome (p = 0.0122). After adjustment for covariates, PSCI was independently associated with risk of recurrent ischemic stroke (HR 2.40, 95% confidence interval 1.12-5.14). CONCLUSIONS: Cognitive impairment was associated with recurrence of ischemic stroke in high risk patients during adequate medical therapy including antiplatelet therapy. However, the other vascular events were not.

Evolution of acute lacunar lesions in terms of size and shape: a PICASSO sub-study.

The imaging definition of lacunar infarcts is variable, particularly regarding their size and the presence of cavitation. We investigated the changes of diameter and evolution pattern of acute lacunar infarcts, and the factors associated with the evolution pattern. Patients with acute single subcortical hemispheric or brainstem ischemic lesions of penetrating arterial territories were included. Maximal diameters on initial diffusion-weighted image (DWI) and follow-up fluid-attenuated inversion recovery image (FLAIR), which performed > 12 months after initial DWI, were semi-automatically measured. Clinical characteristics were compared according to evolution patterns on follow-up FLAIR, classified as cavitated, focal lesion without cavitation, and disappeared. Five hundred nine patients were included. Mean time to follow-up was 31.3 ± 13.7 months. Mean diameter of acute lacunar lesions decreased from 12.9 ± 4.4 to 8.5 ± 4.8 mm during follow-up. Lesions of 58.2% patients remained as cavitated, 18.3% as focal lesion without cavitation, and 23.6% disappeared. Initial NIHSS score (p = 0.005), diameter of initial lesion (p < 0.001), number of slices showing acute lesion on DWI (p < 0.001), progression of white matter lesion (p < 0.001), number of acute lesions involving gray matter (p = 0.008) and lesion location (p < 0.001) were different among three groups. After adjustment for covariates, diameter of the acute lesion, initial number of old lacunes, and anterior lesion location were associated with the appearance of cavitation. Initial lesion diameter and posterior lesion location were associated with the disappearance. We observed reduction of the acute lacunar lesion diameter in 86%. There were predictive factors of disappearance and cavitation of acute lacunar infarction.

Changes in the Common Carotid Artery after Radiotherapy: Wall Thickness, Calcification, and Atherosclerosis.

BACKGROUND AND PURPOSE: Since the long-term survival rate has improved in laryngeal cancer patients who receive radiotherapy, concerns about postradiation complications (including carotid atherosclerosis) have increased. We followed changes in the common carotid artery (CCA) after radiotherapy and identified the underlying risk factors. METHODS: Consecutive patients with laryngeal cancer who underwent radiotherapy between January 1999 and December 2009 and who had received computed tomography (CT) both pre- and postradiotherapy were enrolled. Changes in the wall thickness and in the vessel and lumen areas as well as the presence of calcification or atherosclerosis were investigated. Demographics and risk factors were compared between patients with and without atherosclerosis at follow-up CT. RESULTS: In total, 125 patients were enrolled. The wall thickness had increased and the lumen area had decreased several months after radiotherapy. These changes were not associated with vascular risk factors and were not progressive. Calcification and atherosclerosis were observed in 37 (29.6%) and 71 (56.8%) patients, respectively. Diabetes was associated with calcification (p=0.02). The prevalence of hyperlipidemia was higher in patients with atherosclerosis (28.2% vs. 11.1%, p=0.02) and for a longer period postradiation [62.7±32.1 vs. 40.0±24.2 months (mean±SD), p<0.001]. Atherosclerosis occurred mostly in the middle portion of the CCA (n=31, 24.6%), followed by the proximal CCA at the intrathoracic level (n=26, 20.6%) and the distal CCA (n=6, 4.8%). Positive remodeling was also observed, but this was less common in patients with calcification (p=0.02). CONCLUSIONS: Various types of postradiation changes occur in the CCA and can be easily observed in postradiation CT. The prevalence and burden of postradiation atherosclerosis increased in a close relationship with baseline cholesterol levels and the time after radiotherapy. Postradiation atherosclerosis was observed at unusual sites of the CCA.

Multidisciplinary Approach to Decrease In-Hospital Delay for Stroke Thrombolysis.

BACKGROUND AND PURPOSE: Decreasing the time delay for thrombolysis, including intravenous thrombolysis (IVT) with tissue plasminogen activator and intra-arterial thrombectomy (IAT), is critical for decreasing the morbidity and mortality of patients experiencing acute stroke. We aimed to decrease the in-hospital delay for both IVT and IAT through a multidisciplinary approach that is feasible 24 h/day. METHODS: We implemented the Stroke Alert Team (SAT) on May 2, 2016, which introduced hospital-initiated ambulance prenotification and reorganized in-hospital processes. We compared the patient characteristics, time for each step of the evaluation and thrombolysis, thrombolysis rate, and post-thrombolysis intracranial hemorrhage from January 2014 to August 2016. RESULTS: A total of 245 patients received thrombolysis (198 before SAT; 47 after SAT). The median door-to-CT, door-to-MRI, and door-to-laboratory times decreased to 13 min, 37.5 min, and 8 min, respectively, after SAT implementation (P<0.001). The median door-to-IVT time decreased from 46 min (interquartile range [IQR] 36-57 min) to 20.5 min (IQR 15.8-32.5 min; P<0.001). The median door-to-IAT time decreased from 156 min (IQR 124.5-212.5 min) to 86.5 min (IQR 67.5-102.3 min; P<0.001). The thrombolysis rate increased from 9.8% (198/2,012) to 15.8% (47/297; P=0.002), and the post-thrombolysis radiological intracranial hemorrhage rate decreased from 12.6% (25/198) to 2.1% (1/47; P=0.035). CONCLUSIONS: SAT significantly decreased the in-hospital delay for thrombolysis, increased thrombolysis rate, and decreased post-thrombolysis intracranial hemorrhage. Time benefits of SAT were observed for both IVT and IAT and during office hours and after-hours.

Interfacial chemical bonding-mediated ionic resistive switching.

In this paper, we present a unique resistive switching (RS) mechanism study of Pt/TiO2/Pt cell, one of the most widely studied RS system, by focusing on the role of interfacial bonding at the active TiO2-Pt interface, as opposed to a physico-chemical change within the RS film. This study was enabled by the use of a non-conventional scanning probe-based setup. The nanoscale cell is formed by bringing a Pt/TiO2-coated atomic force microscope tip into contact with a flat substrate coated with Pt. The study reveals that electrical resistance and interfacial bonding status are highly coupled together. An oxygen-mediated chemical bonding at the active interface between TiO2 and Pt is a necessary condition for a non-polar low-resistance state, and a reset switching process disconnects the chemical bonding. Bipolar switching mode did not involve the chemical bonding. The nature of chemical bonding at the TiO2-metal interface is further studied by density functional theory calculations.

Mechanism of Cathodic Performance Enhancement by a Few-Nanometer-Thick Oxide Overcoat on Porous Pt Cathodes of Solid Oxide Fuel Cells.

In a recent report, we demonstrated that few-nanometer-thick yttria-stabilized zirconia (YSZ) coating on a porous Pt cathode of a solid oxide fuel cell is an excellent facilitator of oxygen reduction reaction (ORR) kinetics and an effective suppressor of Pt agglomeration. In this article, we reveal the actual role of the YSZ overcoat in the ORR process through a series of electrochemical analyses. Without the overcoat, the nanoporous Pt is significantly agglomerated during a high-temperature operation and the ORR becomes limited by the availability of triple phase boundaries (TPBs). An ultrathin YSZ overcoat prevents the ORR process from being limited by TPB area by preserving the morphology of its underlying Pt layer. More importantly, the overcoat acts as an excellent facilitator of the atomic-oxygen-species-mediated chemical process(es) that used to be rate-limiting in the ORR of a noncoated Pt/YSZ system.

Plasma-enhanced atomic layer deposition of nanoscale yttria-stabilized zirconia electrolyte for solid oxide fuel cells with porous substrate.

Nanoscale yttria-stabilized zirconia (YSZ) electrolyte film was deposited by plasma-enhanced atomic layer deposition (PEALD) on a porous anodic aluminum oxide supporting substrate for solid oxide fuel cells. The minimum thickness of PEALD-YSZ electrolyte required for a consistently high open circuit voltage of 1.17 V at 500 °C is 70 nm, which is much thinner than the reported thickness of 180 nm using nonplasmatic ALD and is also the thinnest attainable value reported in the literatures on a porous supporting substrate. By further reducing the electrolyte thickness, the grain size reduction resulted in high surface grain boundary density at the cathode/electrolyte interface.

Gender differences in the effect of comorbid insomnia symptom on depression, anxiety, fatigue, and daytime sleepiness in patients with obstructive sleep apnea.

PURPOSE: This study investigated gender differences in the effect of comorbid insomnia symptom on depression, anxiety, fatigue, daytime sleepiness, and quality of life in patients with obstructive sleep apnea. There are gender differences in the presentation of obstructive sleep apnea. However, the influence of gender on the presentation of comorbid insomnia symptom and obstructive sleep apnea is not known. METHODS: Allparticipantsperformed overnightpolysomnography and completed a battery of questionnaires including Beck Depression Inventory, State-Trait Anxiety Inventory, Multidimensional Fatigue Inventory, Epworth Sleepiness Scale, and Short Form-36 Health Survey. Insomnia symptom was defined as present if a patient had any insomnia complaints longer than 1 month and at least one time per week. RESULTS: Six hundred fifty-five adult patients with obstructive sleep apnea were enrolled; 233 (35.5 %) reported comorbid insomnia symptom with obstructive sleep apnea. The severity of obstructive sleep apnea was not related to comorbid insomnia symptom. Based on linear regression, women had higher depression, fatigue, and daytime sleepiness and lower health-related quality of life than men (all, p<0.05). The presence of insomnia symptom had negative effects on fatigue (p=0.005) and quality of life only (p=0.015) in men but not in women when taking gender-by-insomnia interaction into consideration. There were significant differences in polysomnography-based sleep architecture between the obstructive sleep apnea-only and obstructive sleep apnea-insomnia groups, but only in the subgroup of men. CONCLUSIONS: Men are more prone to the negative impact of comorbid insomnia symptom and obstructive sleep apnea on their level of fatigue and quality of life than women.