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Adhesives play a critical role in the assembly of electronic devices, particularly as devices become more diverse in form factors. Flexible displays require highly transparent and rapidly recoverable adhesives with a certain stiffness. In this study, novel structured adhesives are developed that incorporate bicontinuous nanodomains to fabricate flexible adhesives with low moduli. This structure is obtained via polymerization-induced microphase separation using a macro chain transfer agent (CTA). Phase separation is characterized using small-angle X-ray scattering, transmission electron microscopy, and dynamic mechanical analysis. By optimizing the length of the macro CTA, an adhesive with both hard and soft nanodomains is produced, resulting in exceptional flexibility (strain recovery = 93%) and minimal modulus (maximum stress/applied strain = 7 kPa), which overperforms traditional adhesives. The optimized adhesive exhibits excellent resilience under extensive strain, as well as strong adhesion and transparency. Furthermore, dynamic folding tests demonstrate the exceptional stability of the adhesive under various temperature and humidity conditions, which is attributed to its unique structure. In summary, the distinct bicontinuous phase structure confers excellent transparency, flexibility, and reduced stiffness to the adhesive, rendering it well-suited for commercial foldable displays and suggesting potential applications in stretchable displays and wearable electronics.
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Ferromagnetic insulators (FMIs) are intriguing not only due to their rare nature, but also due to their potential applications in spintronics and various electronic devices. One of its key promising applications is based on an FMI-induced magnetic proximity effect, which can impose an effective time-reversal symmetry breaking on the target ultrathin layer to realize novel emergent phenomena. Here, we conduct systematic studies on thin film LaCoO3, an insulator known to be ferromagnet under tensile strain, with varying thicknesses, to establish it as an FMI platform to be integrated in heterostructures. The optimal thickness of the LaCoO3layer, providing a smooth surface and robust ferromagnetism with large remanence, is determined. A heterostructure consisting of an ultrathin target layer (2 uc SrRuO3), the LaCoO3FMI layer, and the La0.5Sr0.5CoO3conducting layer has been fabricated and the angle-resolved photoemission spectroscopy measurement on the multi-layer system demonstrates a sharp Fermi edge and a well-defined Fermi surface without the charging effect. This demonstrates the feasibility of the proposed heterostructure using LaCoO3thin film as the FMI layer, and further lays a groundwork to investigate the magnetic proximity induced phases in quantum materials.
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BACKGROUND: The risk of dementia is increased in subjects with mild cognitive impairment (MCI). Despite the plethora of in-person cognitive tests, those that can be administered over the phone are lacking. We hypothesized that a home-based cognitive test (HCT) using phone calls would be feasible and useful in non-demented elderly. We aimed to assess feasibility and validity of a new HCT as an optional cognitive monitoring tool without visiting hospitals. METHODS: Our study was conducted in a prospective design during 24 weeks. We developed a new HCT consisting of 20 questions (score range 0-30). Participants with MCI (n = 38) were consecutively enrolled and underwent regular HCTs during 24 weeks. Associations between HCT scores and in-person cognitive scores and Alzheimer's disease (AD) biomarkers were evaluated. In addition, HCT scores in MCI participants were cross-sectionally compared with age-matched cognitively normal (n = 30) and mild AD dementia (n = 17) participants for discriminative ability of the HCT. RESULTS: HCT had good intra-class reliability (test-retest Cronbach's alpha 0.839). HCT scores were correlated with the Mini-Mental State Examination (MMSE), verbal memory delayed recall, and Stroop test scores but not associated with AD biomarkers. HCT scores significantly differed among cognitively normal, MCI, and mild dementia participants, indicating its discriminative ability. Finally, 32 MCI participants completed follow-up evaluations, and 8 progressed to dementia. Baseline HCT scores in dementia progressors were lower than those in non-progressors (p = 0.001). CONCLUSION: The feasibility and usefulness of the HCT were demonstrated in elderly subjects with MCI. HCT could be an alternative option to monitor cognitive decline in early stages without dementia.
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Enfermedad de Alzheimer , Disfunción Cognitiva , Demencia , Humanos , Anciano , Reproducibilidad de los Resultados , Estudios de Factibilidad , Disfunción Cognitiva/diagnóstico , Disfunción Cognitiva/psicología , Demencia/diagnóstico , Enfermedad de Alzheimer/diagnóstico , Pruebas Neuropsicológicas , Cognición , BiomarcadoresRESUMEN
Copper-based high-temperature superconductors share a common feature in their crystal structure, which is the presence of a CuO2 plane, where superconductivity takes place. Therefore, important questions arise as to whether superconductivity can exist in a single layer of the CuO2 plane and, if so, how such superconductivity in a single CuO2 plane differs from that in a bulk cuprate system. To answer these questions, studies of the superconductivity in cuprate monolayers are necessary. In this study, we constructed a heterostructure system with a La2-xSrxCuO4 (LSCO) monolayer containing a single CuO2 plane and measured the resulting electronic structures. Monolayer LSCO has metallic and bulk-like electronic structures. The hole doping ratio of the monolayer LSCO is found to depend on the underlying buffer layer due to the interface effect. Our work will provide a platform for research into ideal two-dimensional cuprate systems.
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INTRODUCTION: Studies regarding multiple chronic lacunes (MCLs) and clinical outcome according to stroke etiology are scarce. We sought to evaluate the association between MCL and short-term/long-term clinical outcomes according to stroke etiology. PATIENTS AND METHODS: We analyzed a prospectively collected stroke registry of acute ischemic stroke patients over 4 years. The enrolled patients were classified as having large artery atherosclerosis (LAA), small vessel occlusion (SVO), cardioembolic (CE) stroke, and other etiology. The early neurological deterioration (END) and favorable outcome at 3 months were assessed. RESULTS: A total of 1070 patients were enrolled. Patients with MCL had significantly more END compared to those without MCL both in total population (adjusted odds ratio (OR), 1.7; 95% confidence interval [CI], 1.1-2.5; p = 0.013*) and in the LAA group (adjusted OR, 2.3; 95% CI, 1.3-4.2, p < 0.006). Patients with MCL had a significantly lower OR for favorable outcome at 3 months compared to those without MCL both in total population (adjusted OR, 0.7; 95% CI, 0.5-1.0, p = 0.035) and in the LAA group (adjusted OR, 0.6; 95% CI, 0.3-1.0, p = 0.043). However, MCL was not associated with END or long-term functional outcome in patients with SVO, CE, or other etiology. CONCLUSIONS: The presence of MCL was an independent predictive factor for END as well as long-term poor functional outcome in acute ischemic stroke patients. These associations were only observed in patients with LAA, not in those with SVO, CE, or other etiology.
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Aterosclerosis , Isquemia Encefálica , Accidente Cerebrovascular Isquémico , Accidente Cerebrovascular , Humanos , Accidente Cerebrovascular Isquémico/complicaciones , Accidente Cerebrovascular/epidemiología , Arterias , Isquemia Encefálica/epidemiología , Factores de RiesgoRESUMEN
INTRODUCTION: This study is to explore the long-term functional outcome of antihypertensive medication-naïve, untreated hypertension (HTN) patients with acute ischemic stroke compared to those with no prior HTN and those with treated HTN. PATIENTS AND METHODS: We analyzed a prospectively collected stroke registry of all patients with acute ischemic stroke consecutively admitted to Incheon St. Mary's Hospital. Patients who received reperfusion therapy were excluded. Long-term functional outcomes were assessed at a 3-month follow-up visit using the modified Rankin Scale. RESULTS: A total of 1044 patients was enrolled. Compared to patients with no or treated HTN, those with untreated HTN had higher odds for more favorable outcomes (adjusted odds ratio (OR): 1.7 [95% CI: 1.0-2.7, p = 0.050*] and 1.7 [95% CI: 1.0-2.8, p = 0.047*], respectively) when the stroke was large vessel atherosclerosis (LAA)/cardioembolic (CE) with large vessel occlusion/stenosis. However, no such association was observed when there was no large vessel occlusion or stenosis, in total patients, or if the index stroke was related to SVO. In untreated HTN patients with LAA/CE and large vessel occlusion/stenosis compared to patients in the lowest mean arterial pressure quartile (< 96.7 mmHg), patients in the second and third highest quartiles had higher odds of favorable outcomes. CONCLUSIONS: Patients with untreated HTN had significantly more favorable outcomes at 3 months after ischemic stroke compared to those with no or treated HTN when the stroke was LAA/CE with large vessel occlusion/stenosis. Untreated HTN patients also showed an association between higher MAP and favorable outcomes.
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Aterosclerosis , Isquemia Encefálica , Hipertensión , Accidente Cerebrovascular Isquémico , Accidente Cerebrovascular , Humanos , Accidente Cerebrovascular Isquémico/complicaciones , Isquemia Encefálica/complicaciones , Isquemia Encefálica/terapia , Constricción Patológica , Accidente Cerebrovascular/epidemiología , Accidente Cerebrovascular/terapia , Accidente Cerebrovascular/complicaciones , Pronóstico , Hipertensión/complicaciones , Hipertensión/epidemiología , Resultado del TratamientoRESUMEN
Phytoremediation has emerged as an ecofriendly technique to reduce hazardous particulate matter (PM) in the air. Although previous studies have conducted statistical analyses to reveal PM removal capabilities of various plant species according to their leaf characteristics, the underlying physical mechanism of PM adsorption of plants remains unclear. Conventional methodologies for measuring PM accumulation usually require long-term field tests and provide limited understanding on PM removal effects of individual leaf traits of various plants. In this study, we propose a novel methodology which can compare the electrostatic interactions between PMs and plant leaves according to their trichome structures by using digital in-line holographic microscopy (DIHM). Surface characteristics of Perilla frutescens and Capsicum annuum leaves are measured to examine electrostatic effects according to the morphological features of trichomes. 3D settling motions of PMs near the microstructures of trichomes of the two plant species are compared in detail. To validate the PM removal effect of the hairy microstructures, a polydimethylsiloxane (PDMS) replica model of a P. frutescens leaf is fabricated to demonstrate accelerated settling velocities of PMs near trichome-like microstructures. The size and electric charge distributions of PMs with irregular shapes are analyzed using DIHM. Numerical simulation of the PM deposition near a trichome-like structure is conducted to verify the empirical results. As a result, the settling velocities of PMs on P. frutescens leaves and a PDMS replica sample are 12.11 ± 1.88% and 34.06 ± 4.19% faster than those on C. annuum leaves and a flat PDMS sample, respectively. These findings indicate that the curved microstructures of hairy trichomes of plant leaves increase the ability to capture PMs by enhancing the electric field intensity just near trichomes. Compared with conventional methods, the proposed methodology can quantitatively evaluate the settling velocity of PMs on various plant leaves according to the morphological structure and density of trichomes within a short period of time. The present research findings would be widely utilized in the selection of suitable air-purifying plants for sustainable removal of harmful air pollutants in urban and indoor environments.
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Contaminantes Atmosféricos , Material Particulado , Material Particulado/análisis , Monitoreo del Ambiente/métodos , Contaminantes Atmosféricos/análisis , Plantas , Hojas de la Planta/químicaRESUMEN
We performed in situ angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES (SARPES) experiments to investigate the relationship between electronic band structures and ferromagnetism in SrRuO_{3} (SRO) thin films. Our high quality ARPES and SARPES results show clear spin-lifted band structures. The spin polarization is strongly dependent on momentum around the Fermi level, whereas it becomes less dependent at high-binding energies. This experimental observation matches our dynamical mean-field theory results very well. As temperature increases from low to the Curie temperature, spin-splitting gap decreases and band dispersions become incoherent. Based on the ARPES study and theoretical calculation results, we found that SRO possesses spin-dependent electron correlations in which majority and minority spins are localized and itinerant, respectively. Our finding explains how ferromagnetism and electronic structure are connected, which has been under debate for decades in SRO.
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While Active Hexose Correlated Compound (AHCC) and CpG oligodeoxynucleotide (ODN) are separately known to modulate oxidative stress and immune responses in cancer patients, the combined effect of these two compounds is unknown. To clarify this, we investigated whether AHCC plus KSK-CpG ODN would be therapeutic in B16 melanoma mouse model, if so, and how in reduction-oxidation (redox) balance and cytokines network. We found that treatment groups (AHCC only, KSK-CpG ODN only and AHCC/KSK-CpG ODN) markedly reduced (p<0.001) tumor size when compared to the positive control (PC) group. The total white blood cell (WBC) of AHCC only and KSK-CpG ODN only-treated groups showed significant lower counts than that of PC group. Next, the production of nitric oxide (NO) was significantly increased (p<0.01) in AHCC/KSK-CpG ODN group compared to the PC group. Further, the redox balance was improved in AHCC/KSK-CpG ODN group through significantly low (p<0.001) reactive oxygen species (ROS) production and significantly high (p<0.05) glutathione peroxidase (GPx) activity compared to the PC group. Finally, AHCC/KSK-CpG ODN (p<0.01) and KSK-CpG ODN (p<0.001)-treated groups augmented tumor immune surveillance as shown by significantly increased level of anti-inflammatory cytokine (IL-10) and significantly decreased (p<0.05) level of pro-tumorigenic IL-6 of AHCC/KSK-CpG ODN treated group as compared to the PC group. Collectively, our study indicates therapeutic effect of Active Hexose-Correlated Compound (AHCC) combined with KSK-CpG ODN in B16 melanoma murine model via balancing redox and cytokines network.
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Melanoma Experimental/tratamiento farmacológico , Melanoma Experimental/inmunología , Oligodesoxirribonucleótidos/uso terapéutico , Polisacáridos/uso terapéutico , Animales , Línea Celular Tumoral , Citocinas/sangre , Citocinas/química , Citocinas/inmunología , Modelos Animales de Enfermedad , Quimioterapia Combinada , Femenino , Glutatión Peroxidasa/sangre , Interleucina-10/sangre , Interleucina-12/sangre , Interleucina-6/sangre , Células Asesinas Naturales/inmunología , Melanoma Experimental/metabolismo , Ratones Endogámicos C57BL , Óxido Nítrico/sangre , Oxidación-Reducción , Estrés Oxidativo , Distribución Aleatoria , Especies Reactivas de Oxígeno/sangreRESUMEN
BACKGROUND: Microglia are involved in immune surveillance in intact brains and become activated in response to inflammation and neurodegeneration. Microglia have different functions, neuroprotective or neurotoxic, according to aging in patients with PD. The clinical effect of microglia in patients with Alzheimer's disease (AD) is poorly defined. This prospective study was conducted to investigate the clinical effects of microglia according to the aging process in newly diagnosed AD. METHODS: We examined 532 patients with newly diagnosed AD and 119 healthy controls, and the differences in hs-CRP between these groups were investigated. The patients with AD were classified into 3 subgroups according to age of newly diagnosed AD to investigate the relationship between hs-CRP and the aging process in newly diagnosed AD. RESULTS: There was significantly higher serum high-sensitivity C-reactive protein (hs-CRP), levels in patients with AD compared with healthy controls. A post-hoc analysis of the 3 AD subgroups showed no significant differences in serum hs-CRP level between each group. CONCLUSION: We assumed that neuroinflammation play a role in the pathogenesis of AD, but found no clinical evidence that microglia senescence underlies the microglia switch from neuroprotective in young brains to neurotoxic in aged brains. To clarify the role of microglia and aging in the pathogenesis of AD, future longitudinal studies involving a large cohort are required.
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Envejecimiento/sangre , Enfermedad de Alzheimer/sangre , Biomarcadores/sangre , Proteína C-Reactiva/metabolismo , Anciano , Anciano de 80 o más Años , Encéfalo/patología , Estudios de Casos y Controles , Femenino , Humanos , Inflamación/patología , Imagen por Resonancia Magnética , Masculino , Microglía/patología , Enfermedades Neurodegenerativas/patología , Neuronas/patología , Estudios ProspectivosRESUMEN
Introduction: Women can experience various reproductive events, such as pregnancy, childbirth, lactation, and contraception, which cause long-term changes in female hormones. In middle-aged women, the prevalence of migraine is high, and a clear gender difference is evident. This study investigated the effects of factors associated with past reproductive events on the risk of new migraine in middle-aged premenopausal women. Methods: The influence of reproductive factors on migraine in middle-aged women was investigated using the Korean National Health Insurance Service (KNHIS) and Korean Health Examination (KHE) databases. The reproductive factors of interest were parity, breastfeeding, and oral contraceptive (OC) use. The study included 949,704 middle-aged premenopausal women 40-60 years of age. The study population was divided into two groups based on new diagnosis of migraine during the follow-up period (2009-2018). Results: The risk of new migraine tended to increase in the primiparous (hazard ratio, HR: 1.179; 95% confidence interval, CI: 1.137-1.221) and multiparous groups (HR: 1.181; 95% CI: 1.142-1.221) compared with the nulliparous group. The breastfeeding ≥12 months group (HR: 1.071; 95% CI: 1.052-1.091) showed a significantly increased risk of new migraine compared with the non-breastfeeding group. All women in the OC groups (< 1 year, HR: 1.048; 95% CI: 1.028-1.069 and ≥ 1 year, HR: 1.100; 95% CI: 1.067-1.134) showed a higher risk of new migraine than those in the non-OC group. Conclusion: The results of the current study indicate that childbirth, longer breastfeeding, and OC use may be associated with a higher risk of new migraine in middle-aged premenopausal women.
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With growing sustainability concerns, the need for products that facilitate easy disassembly and reuse has increased. Adhesives, initially designed for bonding, now face demands for selective removal, enabling rapid assembly-disassembly and efficient maintenance across industries. This need is particularly evident in the display industry, with the rise of foldable devices necessitating specialized adhesives. A novel optically clear adhesive (OCA) is presented for foldable display, featuring a unique UV-stimulated selective removal feature. This approach incorporates benzophenone derivatives into the polymer network, facilitating rapid debonding under UV irradiation. A key feature of this method is the adept use of visible-light-driven radical polymerization for OCA film fabrication. This method shows remarkable compatibility with various monomers and exhibits orthogonal reactivity to benzophenone, rendering it ideal for large-scale production. The resultant OCA not only has high transparency and balanced elasticity, along with excellent resistance to repeated folding, but it also exhibits significantly reduced adhesion when exposed to UV irradiation. By merging this customized formulation with strategically integrated UV-responsive elements, an effective solution is offered that enhances manufacturing efficiency and product reliability in the rapidly evolving field of sustainable electronics and displays. This research additionally contributes to eco-friendly device fabrication, aligning with emerging technology demands.
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In developing an organic light-emitting diode (OLED) panel for a foldable smartphone (specifically, a color filter on encapsulation) aimed at reducing power consumption, the use of a new optically clear adhesive (OCA) that blocks UV light was crucial. However, the incorporation of a UV-blocking agent within the OCA presented a challenge, as it restricted the traditional UV-curing methods commonly used in the manufacturing process. Although a visible-light curing technique for producing UV-blocking OCA was proposed, its slow curing speed posed a barrier to commercialization. Our study introduces a highly efficient photo-initiating system (PIS) for the rapid production of UV-blocking OCAs utilizing visible light. We have carefully selected the photocatalyst (PC) to minimize electron and energy transfer to UV-blocking agents and have chosen co-initiators that allow for faster electron transfer and more rapid PC regeneration compared to previously established amine-based co-initiators. This advancement enabled a tenfold increase in the production speed of UV-blocking OCAs, while maintaining their essential protective, transparent, and flexible properties. When applied to OLED devices, this OCA demonstrated UV protection, suggesting its potential for broader application in the safeguarding of various smart devices.
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Neurotechnologies and genetic tools for dissecting neural circuit functions have advanced rapidly over the past decade, although the development of complementary pharmacological method-ologies has comparatively lagged. Understanding the precise pharmacological mechanisms of neuroactive compounds is critical for advancing basic neurobiology and neuropharmacology, as well as for developing more effective treatments for neurological and neuropsychiatric disorders. However, integrating modern tools for assessing neural activity in large-scale neural networks with spatially localized drug delivery remains a major challenge. Here, we present a dual microfluidic-photometry platform that enables simultaneous intracranial drug delivery with neural dynamics monitoring in the rodent brain. The integrated platform combines a wireless, battery-free, miniaturized fluidic microsystem with optical probes, allowing for spatially and temporally specific drug delivery while recording activity-dependent fluorescence using genetically encoded calcium indicators (GECIs), neurotransmitter sensors GRAB NE and GRAB DA , and neuropeptide sensors. We demonstrate the performance this platform for investigating neuropharmacological mechanisms in vivo and characterize its efficacy in probing precise mechanistic actions of neuroactive compounds across several rapidly evolving neuroscience domains.
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Previous studies have demonstrated a decreased density of dopamine transporters (DAT) in basal ganglia in patients with idiopathic Parkinson disease (IPD) using I-n-fluoropropyl-2b-carbomethoxy-3b-(4-iodophenyl) nortropane (FP-CIT), and the reductions in striatal DAT levels were inversely correlated with the severity of motor dysfunction in IPD. However, there has been no study on the correlation of DAT levels between IPD patients with and without cognitive dysfunction. Thus, we evaluated the differences in regional DAT density in the brain of patients with IPD without dementia and those with dementia using FP-CIT positron emission tomography. We recruited 24 consecutive patients with IPD, including 7 with IPD without dementia and 17 with IPD with dementia, and 18 healthy controls. FP-CIT positron emission tomography scans were acquired 90 and 210 minutes after the FP-CIT injection. The DAT density did not differ in the caudate nucleus or the putamen between patients with IPD without dementia and those with dementia. However, the DAT density between the 2 groups with IPD demonstrated a significantly decreased density compared with that of healthy controls in the putamen. We cautiously suggest that there is no relationship between DAT density and cognitive severity because there were no significant differences in the DAT density between IPD with dementia and those without dementia.
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Demencia/diagnóstico por imagen , Neuronas Dopaminérgicas/diagnóstico por imagen , Enfermedad de Parkinson/diagnóstico por imagen , Radiofármacos , Tropanos , Anciano , Encéfalo/diagnóstico por imagen , Encéfalo/patología , Demencia/etiología , Demencia/patología , Neuronas Dopaminérgicas/patología , Femenino , Humanos , Interpretación de Imagen Asistida por Computador , Masculino , Enfermedad de Parkinson/complicaciones , Enfermedad de Parkinson/patología , Tomografía de Emisión de Positrones/métodosRESUMEN
The morphological and mechanical characteristics of red blood cells (RBCs) largely vary depending on the occurrence of hematologic disorders. Variations in the rheological properties of RBCs affect the dynamic motions of RBCs, especially their rotational behavior. However, conventional techniques for measuring the orientation of biconcave-shaped RBCs still have some technical limitations, including complicated optical setups, complex post data processing, and low throughput. In this study, we propose a novel image-based technique for measuring 3D position and orientation of normal RBCs using digital in-line holographic microscopy (DIHM) and artificial intelligence (AI). Formaldehyde-fixed RBCs are immobilized in coagulated polydimethylsiloxane (PDMS). Holographic images of RBCs positioned at various out-of-plane angles are acquired by precisely manipulating the PDMS-trapped RBC sample attached to a 4-axis optical stage. With the aid of deep learning algorithms for data augmentation and regression analysis, the out-of-plane angle of RBCs is directly predicted from the captured holographic images. The 3D position and in-plane angle of RBCs are acquired by employing numerical reconstruction and ellipse detection methods. Combining these digital image processing techniques, the 3D positional and orientational information of each RBC recorded in a single holographic image is measured within 23.5 and 3.07 s, respectively. The proposed AI-based DIHM technique that can extract the 3D position, orientation, and morphology of individual RBCs would be utilized to analyze the dynamic translational and rotational motions of abnormal RBCs with hematologic disorders in shear flows through further research.
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Técnicas Biosensibles , Holografía , Microscopía/métodos , Inteligencia Artificial , Holografía/métodos , EritrocitosRESUMEN
Current technological advances in the organic light-emitting diode panel design of foldable smartphones demand advanced adhesives with UV-blocking abilities, beyond their conventional roles of bonding objects and relieving deformation stress. However, optically clear adhesives (OCAs) with UV-blocking ability cannot be prepared using conventional UV-curing methods relying on a photoinitiator. Herein, a new acrylic resin that can be efficiently cured using visible light without oxygen removal is presented, which may be used to develop UV-blocking OCAs for use in current flexible displays. A novel photocatalyst and a specific combination of additives facilitate sufficiently rapid curing under visible light in the presence of UV-absorbers. Only a very small amount of the highly active photocatalyst is required to prepare UV-blocking OCA films with very high transparency in the visible region. Using this system, a UV-blocking OCA that nearly meets the specifications of an OCA used in commercialized foldable smartphones is realized. This technology can also be utilized in other applications that require highly efficient visible light curing, such as optically clear resins, dental resins, and 3D/4D-printable materials.
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Hund's rule coupling (J) has attracted much attention recently for its role in the description of the novel quantum phases of multi-orbital materials. Depending on the orbital occupancy, J can lead to various intriguing phases. However, experimental confirmation of the orbital occupancy dependency has been difficult as controlling the orbital degrees of freedom normally accompanies chemical inhomogeneities. Here, we demonstrate a method to investigate the role of orbital occupancy in J related phenomena without inducing inhomogeneities. By growing SrRuO3 monolayers on various substrates with symmetry-preserving interlayers, we gradually tune the crystal field splitting and thus the orbital degeneracy of the Ru t2g orbitals. It effectively varies the orbital occupancies of two-dimensional (2D) ruthenates. Via in-situ angle-resolved photoemission spectroscopy, we observe a progressive metal-insulator transition (MIT). It is found that the MIT occurs with orbital differentiation: concurrent opening of a band insulating gap in the dxy band and a Mott gap in the dxz/yz bands. Our study provides an effective experimental method for investigation of orbital-selective phenomena in multi-orbital materials.
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Proyectos de Investigación , Sarcómeros , Espectroscopía de FotoelectronesRESUMEN
Interfaces between dissimilar correlated oxides can offer devices with versatile functionalities, and great efforts have been made to manipulate interfacial electronic phases. However, realizing such phases is often hampered by the inability to directly access the electronic structure information; most correlated interfacial phenomena appear within a few atomic layers from the interface. Here, atomic-scale epitaxy and photoemission spectroscopy are utilized to realize the interface control of correlated electronic phases in atomic-scale ruthenate-titanate heterostructures. While bulk SrRuO3 is a ferromagnetic metal, the heterointerfaces exclusively generate three distinct correlated phases in the single-atomic-layer limit. The theoretical analysis reveals that atomic-scale structural proximity effects yield Fermi liquid, Hund metal, and Mott insulator phases in the quantum-confined SrRuO3 . These results highlight the extensive interfacial tunability of electronic phases, hitherto hidden in the atomically thin correlated heterostructure. Moreover, this experimental platform suggests a way to control interfacial electronic phases of various correlated materials.