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PURPOSE: We examined regression patterns in pediatric optic pathway gliomas (OPGs) after proton beam therapy (PBT) and evaluated local control and visual outcomes. METHODS: A total of 42 brain magnetic resonance imaging (MRI) scans from seven consecutive sporadic OPGs that were initially treated with chemotherapy and received PBT between June 2007 and September 2016 at the National Cancer Center, Korea were analyzed. Patients underwent brain MRI regularly before and after PBT. Total tumor, cystic lesion, and solid enhancing lesion area delineation and volume calculations were performed on gadolinium-enhanced T1-weighted MRI using Eclipse version 13, Varian. RESULTS: The median follow-up period after PBT was 70 months (range 47-88). The median age at the time of PBT was 7 years (range 4-16) and the median duration of chemotherapy before referral to PBT center was 25 months (range 3-70). The median time to the greatest increase in cystic volume was 32 months (range 12-43) after PBT. Solid enhancing lesion volume gradually decreased throughout the follow-up period. On an individual basis, total volume change was varied. However, on average, it regressed, although at a slower rate than solid enhancing lesion volume did. The local control rate was 85.7% (5-year progression-free survival rate, 80%; 5-year overall survival rate, 100%) and the rate of vision preservation was 71.4% (five of seven patients). CONCLUSION: The regression patterns in pediatric OPGs after PBT involve significant cystic change. Therefore, total volume is not appropriate for evaluating response. Care by a multidisciplinary team is necessary to manage clinical symptoms related to radiologic changes.
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Glioma do Nervo Óptico , Terapia com Prótons , Encéfalo , Criança , Humanos , Lactente , Imageamento por Ressonância Magnética , Glioma do Nervo Óptico/radioterapia , Terapia com Prótons/métodos , Estudos RetrospectivosRESUMO
Recently, temperature monitoring with practical colorimetric sensors has been highlighted because they can directly visualize the temperature of surfaces without any power sources or electrical transducing systems. Accordingly, several colorimetric sensors that convert the temperature change into visible color alteration through various physical and chemical mechanisms have been proposed. However, the colorimetric temperature sensors that can be used at subzero temperatures and detect a wide range of temperatures have not been sufficiently explored. Here, we present a colorimetric sensory system that can detect and visualize a wide range of temperatures, even at a temperature below 0 °C. This system was developed with easily affordable materials via a simple fabrication method. The sensory system is mainly fabricated using hydroxypropyl cellulose (HPC) and ethylene glycol as the coolant. In this system, HPC can self-assemble into a temperature-responsive cholesteric liquid crystalline mesophase, and ethylene glycol can prevent the mesophase from freezing at low temperatures. The colorimetric sensory system can quantitatively visualize the temperature and show repeatability in the temperature change from -20 to 25 °C. This simple and reliable sensory system has great potential as a temperature-monitoring system for structures exposed to real environments.
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Colorimetria , Cristais Líquidos , Celulose/análogos & derivados , TemperaturaRESUMO
PURPOSE: Direct comparative results of patients with early stiffness after arthroscopic rotator cuff repair (ARCR) with and without steroid injection are still unclear. This study aimed to evaluate the clinical and structural effect of intra-articular steroid injection for early stiffness after ARCR. METHODS: From 2011 and 2016, a total of 417 patients who underwent ARCR for less than medium-sized tears with 35.8 ± 22.6 months follow-up were retrospectively analyzed. Patients with shoulder stiffness [forward flexion (FF) < 120Ë] or pain at 2 months after ARCR were performed intra-articular steroid injection, and four groups were established [+ stiffness/ + injection (SI, 158 patients), + stiffness/-injection (SNI, 92 patients), -stiffness/ + injection (NSI, 33 patients), and -stiffness/-injection (NSNI, 134 patients)]. Shoulder range-of-motion (ROM) and functional score changes for over two years were analyzed, and six month tendon integrity were evaluated using magnetic resonance imaging. RESULTS: Comparing SI and SNI group, ROM (except internal rotation) and functional score changes did not differ during the early period (2-6 and 2-12 months). However, comparing whether steroid injected (SI/NSI) or not (SNI/NSNI), the formers showed significantly higher improvement of both ROM and functional scores during the early and late period (2-24 months). A six month tendon integrity was not different across four groups and whether steroid injected or not. CONCLUSIONS: Intra-articular steroid injections do not appear to have a short-term clinical improving effect by comparing patients with stiff shoulders after ARCR with and without steroid injections. However, intra-articular steroid injection at two months after ARCR did not affect the tendon integrity at post-operative six months.
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Lesões do Manguito Rotador , Articulação do Ombro , Artroscopia/efeitos adversos , Artroscopia/métodos , Humanos , Injeções Intra-Articulares , Imageamento por Ressonância Magnética , Amplitude de Movimento Articular , Estudos Retrospectivos , Manguito Rotador/cirurgia , Lesões do Manguito Rotador/tratamento farmacológico , Lesões do Manguito Rotador/cirurgia , Articulação do Ombro/cirurgia , Resultado do TratamentoRESUMO
Lead halide perovskite is one of the attractive functional materials owing to its outstanding opto-electronic properties, which have been addressed in numerous studies. This study aims to clarify the link between the growth pattern and the charge carrier related properties for the highly oriented perovskite film along the [100] direction. For this purpose, a CH3 NH3 PbI3 thin film mainly grown along the [100] direction was fabricated and subjected to spectroscopic analysis to understand the basic optoelectronic features of the oriented film. A perovskite film with random growth was also fabricated for comparison. In particular, results from excitation polarization photoluminescence spectroscopy (ExPPS) revealed that the orientation of transition dipole moment, which is relevant to the anisotropic property of the film, is attributed to the growth direction of the perovskite film. This study suggests that the absorption anisotropy can affect the anisotropy in properties of the perovskite device. Furthermore, photodetectors with the perovskite films were fabricated to investigate the effect of growth direction on the photodetector performances, revealing that a photodetector with the oriented perovskite film showed larger photoresponses. In order to provide an explanation for such result, we performed a PL lifetime imaging study of the oriented and randomly grown perovskite films.
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When a liquid drop impacts on a heated substrate, it can remain deposited, or violently boil in contact, or lift off with or without ever touching the surface. The latter is known as the Leidenfrost effect. The duration and area of the liquid-substrate contact are highly relevant for the heat transfer, as well as other effects such as corrosion. However, most experimental studies rely on side view imaging to determine contact times, and those are often mixed with the time until the drop lifts off from the substrate. Here, we develop and validate a reliable method of contact time determination using high-speed X-ray imaging and total internal reflection imaging. We exemplarily compare contact and lift-off times on flat silicon and sapphire substrates. We show that drops can rebound even without formation of a complete vapor layer, with a wide range of lift-off times. On sapphire, we find a local minimum of lift-off times that is much shorter than expected from capillary rebound in the comparatively low-temperature regime of transition boiling/thermal atomization. We elucidate the underlying mechanism related to spontaneous rupture of the lamella and receding of the contact area.
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We report lightly Ag/Mn co-doped CdS/ZnS (core/shell) nanocrystals (NCs) as a model system for studying interactions between co-dopants and between NCs and dopants. The co-doped NCs were prepared with a varying average number of Ag dopant atoms per CdS core of the NC from zero to eight; at the same time, the depth profile of the Mn dopants in the ZnS shells was controlled to be either close to or far from the Ag dopants. The incorporation of an average of one to two Ag dopant atoms per NC increased the band-edge photoluminescence (PL); however, it was quenched at higher doping concentration. This alternation is attributed to change of the Ag ion occupancy from PL-enhancing interstitial sites to PL-quenching substitutional sites. Mn PL increased as the number of Ag atoms per NC increased up to approximately seven and then decreased. For NCs doped only with Ag ions, the Ag dopants in substitutional sites acted as PL-quenching hole traps. In Ag/Mn co-doped NCs, the Ag dopants acted as Dexter-type relay sites that enhanced the energy transfer from NC to Mn ions; this effect increased as the distance between Ag and Mn dopants decreased. This model study demonstrates that the simultaneous control of dopant concentrations and spatial distributions in co-doped semiconductor NCs enables sophisticated control of their optical properties.
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INTRODUCTION: A flexible reamer system (FRS) for transportal anterior cruciate ligament reconstruction (ACLR) has been developed to overcome the technical challenges of a rigid reamer system. The purpose of this study was to investigate the safety and effectiveness of the two-portal technique using an FRS by evaluating femoral tunnel geometry. METHODS: This study included 30 patients (mean age 30 ± 12.1) who underwent transportal single-bundle ACLR. Operations were performed with the two-portal technique using an FRS. Three-dimensional computed tomography was performed for all patients 2 days after the operation. The femoral tunnel position, femoral graft bending angle, femoral tunnel length, and posterior wall breakage were evaluated. These radiologic outcomes were compared to previous literature-reported outcomes. RESULTS: The mean distances (measured as a percentage) from the posterior wall and the intercondylar notch roof to the femoral tunnel center were 29.6 ± 5.5% and 20.1 ± 6.7%, respectively. The femoral graft bending angle (108.4° ± 6.9°) was similar to that associated with the traditional transportal technique using a rigid reamer system, but it was less acute than that associated with the three-portal technique using an FRS. The femoral tunnel length (32.8 ± 4.5 mm) was also similar to the results of the traditional transportal technique using a rigid reamer system, but it was shorter than that of three-portal technique using an FRS. The prevalence of posterior wall breakage was as low as the reported outcomes of the outside-in technique (2 cases, 6.6%). CONCLUSIONS: The two-portal technique for transportal ACLR using an FRS can achieve comparable femoral graft bending angle and femoral tunnel length compared with the conventional three-portal technique using the rigid reamer system and had a low risk of posterior wall breakage. Therefore, the two-portal technique using the FRS can be considered a safe and effective method for transportal ACLR. LEVEL OF EVIDENCE: Retrospective case series; level of evidence, 4.
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Reconstrução do Ligamento Cruzado Anterior , Adolescente , Adulto , Ligamento Cruzado Anterior/cirurgia , Lesões do Ligamento Cruzado Anterior/cirurgia , Reconstrução do Ligamento Cruzado Anterior/efeitos adversos , Reconstrução do Ligamento Cruzado Anterior/instrumentação , Reconstrução do Ligamento Cruzado Anterior/métodos , Humanos , Estudos Retrospectivos , Adulto JovemRESUMO
PURPOSE: Magnetic resonance imagining (MRI) is helpful for diagnosis of leptomeningeal carcinomatosis (LMC) and localizing LMC symptoms. Goal of this study is how MRI findings of LMC are associated with clinical characteristics or prognosis in patients with non-small cell lung cancer (NSCLC). METHODS: We retrospectively collected data on 283 patients with LMC from NSCLC, adenocarcinoma based on cerebrospinal fluid cytology. All patients had brain MRI with gadolinium enhancement at LMC diagnosis, and spinal MRI was performed at the physician's discretion. We evaluated the prognostic factors for overall survival (OS) of all patients and subgroup of patients with central nervous system cause of death. RESULTS: Two-hundred sixteen patients (76%) had definite or suggestive LMC findings and 67 had negative findings on brain MRI. Of the 37 patients who presented with cauda equina syndrome, 35 (95%) exhibited typical spinal MRI findings. Median OS of all patients was 3.65 months (95% confidence interval, 3.06-4.18). There was no significant difference in median OS between MRI-negative and MRI-positive groups (4.31 vs. 3.48 months, p = 0.711), whereas negative MRI finding showed longer median OS significantly in a subgroup of 77 patients with a central nervous system cause of death (p = 0.035). Considering clinical characteristics, progressive systemic disease, and altered mentality were significant prognostic factors associated with poor OS, whereas presenting symptom of headache with nausea/vomiting, intra-CSF chemotherapy, WBRT after LMC diagnosis, and concurrent RTKi treatment were significant for favorable OS in multivariable analysis. CONCLUSIONS: Positive MRI findings suggests heavier disease burden than negative MRI findings in patients with LMC who died of a central nervous system cause. Spinal MRI findings in patients with LMC correlate with cauda equina symptoms.
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Adenocarcinoma de Pulmão/mortalidade , Carcinoma Pulmonar de Células não Pequenas/mortalidade , Neoplasias Pulmonares/mortalidade , Imageamento por Ressonância Magnética/métodos , Carcinomatose Meníngea/mortalidade , Adenocarcinoma de Pulmão/complicações , Adenocarcinoma de Pulmão/patologia , Adenocarcinoma de Pulmão/radioterapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma Pulmonar de Células não Pequenas/complicações , Carcinoma Pulmonar de Células não Pequenas/patologia , Carcinoma Pulmonar de Células não Pequenas/radioterapia , Feminino , Seguimentos , Humanos , Neoplasias Pulmonares/complicações , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/radioterapia , Masculino , Carcinomatose Meníngea/etiologia , Carcinomatose Meníngea/patologia , Carcinomatose Meníngea/radioterapia , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Taxa de SobrevidaRESUMO
Low-dimensional nanomaterials are widely adopted as active sensing elements for electronic skins. When the nanomaterials are integrated with microscale architectures, the performance of the electronic skin is significantly altered. Here, it is shown that a high-performance flexible and stretchable electronic skin can be produced by incorporating a piezoresistive carbon nanotube composite into a hierarchical topography of micropillar-wrinkle hybrid architectures that mimic wrinkles and folds in human skin. Owing to the unique hierarchical topography of the hybrid architectures, the hybrid electronic skin exhibits versatile and superior sensing performance, which includes multiaxial force detection (normal, bending, and tensile stresses), remarkable sensitivity (20.9 kPa-1 , 17.7 mm-1 , and gauge factor of 707 each for normal, bending, and tensile stresses), ultrabroad sensing range (normal stress = 0-270 kPa, bending radius of curvature = 1-6.5 mm, and tensile strain = 0-50%), sensing tunability, fast response time (24 ms), and high durability (>10 000 cycles). Measurements of spatial distributions of diverse mechanical stimuli are also demonstrated with the multipixel electronic skin. The stress-strain behavior of the hybrid structure is investigated by finite element analysis to elucidate the underlying principle of the superior sensing performance of the electronic skin.
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OBJECTIVES: The most appropriate treatments for brain metastases from ovarian cancer have not been established mainly because of its rarity. The objective of this study was to describe clinical results of treatment and prognostic factors of patients with brain metastases from ovarian cancer treated at a single institution. MATERIALS AND METHODS: We retrieved information from the electronic medical records of 56 consecutive patients (2.8%) with brain metastases, from a total of 2008 patients with ovarian cancer. Endpoints were the pattern of treatment failure, progression-free survival, and overall survival (OS). RESULTS: Radiation was the most common initial treatment for brain metastases (59%), followed by surgery (23%). The median progression-free survival was 9.8 months. Radiological progression was confirmed in 20 patients: 7 had leptomeningeal carcinomatosis (37%), 8 had local recurrence, and 5 had distant recurrence. Median OS was 11.25 months, and the 1-year OS rate was 48.2%. Patients received surgery for single metastasis as initial treatment showed median OS of 24.1 months, which was significantly prolonged compared with the other patients (P = 0.0002). Of the 48 patients who died, 29 (60%) died of systemic disease and 7 (15%) died of central nervous system progression. Karnofsky Performance Status greater than or equal to 70, control of systemic cancer, serous histology, and surgery for brain metastases were associated with improved OS in multivariable analysis (P < 0.05). CONCLUSIONS: Surgical resection for single or symptomatic brain metastases from ovarian cancer prolonged OS significantly. Multimodality treatment, including control of systemic cancer, appeared to be an important factor in prolonging OS.
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Neoplasias Encefálicas/secundário , Neoplasias Encefálicas/terapia , Neoplasias Ovarianas/patologia , Neoplasias Ovarianas/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/cirurgia , Feminino , Humanos , Pessoa de Meia-Idade , Neoplasias Ovarianas/radioterapia , Neoplasias Ovarianas/cirurgia , Intervalo Livre de Progressão , Estudos RetrospectivosRESUMO
The photophysical properties of a series of highly π-conjugated benzoporphyrin molecules (s) with different shapes were investigated in the condensed phase using single-molecule fluorescence spectroscopy. The fluorescence properties of single s were found to be affected by the number of porphyrin units and their molecular shapes. Notably, the single-molecule fluorescence dynamics of the s revealed an increase in the fluorescence lifetimes and blue shifts of the fluorescence spectra indicative of decreasing π-conjugation pathways in the molecules. The distributions of the spectroscopic parameters and the photostability for the molecules also suggest conformational complexities and heterogeneities. Specifically, as the number of constituent porphyrin units increased, the one-step photobleaching behavior ratio and photostability decreased, and the spectroscopic parameter distributions broadened. The structural properties of the s were also directly determined using defocused wide-field imaging and linear dichroism analyses. In particular, molecules with the same number of constituent porphyrins but different molecular shapes exhibited distinct photophysical properties. In summary, these observations provide guidance for the design of molecular systems that can enhance the performance of molecular electronic devices.
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BACKGROUND: Health problems related to the lack of bone formation are a major problem for ageing populations in the modern world. As a part of the ongoing trend to develop natural substances that attenuate bone loss in osteoporosis, the effects of the edible brown alga Sargassum thunbergii and its active contents on adipogenic differentiation in 3T3-L1 fibroblasts and osteoblast differentiation in MC3T3-E1 pre-osteoblasts were evaluated. RESULTS: Treatment with S. thunbergii significantly reduced lipid accumulation and expression of adipogenic differentiation markers such as peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein α and sterol regulatory element binding protein 1c. In addition, S. thunbergii successfully enhanced osteoblast differentiation as indicated by increased alkaline phosphatase activity along raised levels of osteoblastogenesis indicators, namely bone morphogenetic protein-2, osteocalcin and collagen type I. Two compounds, sargaquinoic and sargahydroquinoic acid, were isolated from active extract and shown to be active by means of osteogenesis inducement. CONCLUSION: S. thunbergii could be a source for functional food ingredients for improved treatment of osteoporosis and obesity.
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Adipogenia/efeitos dos fármacos , Osteoblastos/fisiologia , Osteogênese/efeitos dos fármacos , Quinonas/farmacologia , Sargassum/química , Células 3T3-L1 , Alcenos/isolamento & purificação , Alcenos/farmacologia , Animais , Benzoquinonas/isolamento & purificação , Benzoquinonas/farmacologia , Proteína alfa Estimuladora de Ligação a CCAAT/análise , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Lipídeos/análise , Camundongos , PPAR gama/análise , Proteína de Ligação a Elemento Regulador de Esterol 1/análiseRESUMO
Atomically thin 2D transition metal dichalcogenides (TMDs) have recently been spotlighted for next-generation electronic and photoelectric device applications. TMD materials with high carrier mobility have superior electronic properties different from bulk semiconductor materials. 0D quantum dots (QDs) possess the ability to tune their bandgap by composition, diameter, and morphology, which allows for a control of their light absorbance and emission wavelength. However, QDs exhibit a low charge carrier mobility and the presence of surface trap states, making it difficult to apply them to electronic and optoelectronic devices. Accordingly, 0D/2D hybrid structures are considered as functional materials with complementary advantages that may not be realized with a single component. Such advantages allow them to be used as both transport and active layers in next-generation optoelectronic applications such as photodetectors, image sensors, solar cells, and light-emitting diodes. Here, recent discoveries related to multicomponent hybrid materials are highlighted. Research trends in electronic and optoelectronic devices based on hybrid heterogeneous materials are also introduced and the issues to be solved from the perspective of the materials and devices are discussed.
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It is self-evident that our chests expand and contract during breathing but, surprisingly, exactly how individual alveoli change shape over the respiratory cycle is still a matter of debate. Some argue that all the alveoli expand and contract rhythmically. Others claim that the lung volume change is due to groups of alveoli collapsing and reopening during ventilation. Although this question might seem to be an insignificant detail for healthy individuals, it might be a matter of life and death for patients with compromised lungs. Past analyses were based on static post-mortem preparations primarily due to technological limitations, and therefore, by definition, incapable of providing dynamic information. In contrast, this study provides the first comprehensive dynamic data on how the shape of the alveoli changes, and, further, provides valuable insights into the optimal lung volume for efficient gas exchange. It is concluded that alveolar micro-dynamics is nonlinear; and at medium lung volume, alveoli expand more than the ducts.
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Alvéolos Pulmonares , Síncrotrons , Animais , Alvéolos Pulmonares/fisiologia , Volume de Ventilação Pulmonar/fisiologiaRESUMO
The purpose of the present study was to analyze the survival rate of implants and mode of failure after revision total knee arthroplasty (TKA) using one type of modular prosthesis by a single surgeon. From September 1990 to June 2009, 224 revision TKAs were performed in 194 patients. The 5-, 8-, and 10-year survival rates were 97.2%, 91.6%, and 86.1%, respectively. Re-revision TKAs were performed in 20 knees because of infection (seven knees), loosening (six knees), polyethylene wear (six knees), and periprosthetic fractures (one knee). The long-term survival rate of revision TKA was satisfactory, but careful attention is necessary to detect the late failure. The prevention of infection and the stable fixation of components are required at the time of revision TKA.
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Artroplastia do Joelho/métodos , Prótese do Joelho , Falha de Prótese , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reoperação , Taxa de Sobrevida , Falha de TratamentoRESUMO
As point-of-care testing (POCT) is becoming the new paradigm of medical diagnostics, there is a growing need to develop reliable POCT devices that can be conveniently operated in a minimally invasive manner. However, the clinical potential of POCT diagnostics is yet to be realized, mainly due to the limited and inconsistent amount of collected samples on these devices, undermining their accuracy. This study proposes a new biosensing platform modified with a functional polysuccinimide (PSI)-silica nanoparticle (SNP) composite system that can substantially increase the protein conjugation efficiency by modulating physicochemical interaction with proteins by several hundred percent from an unmodified device. The efficacy of this PSI-SNP system is further validated by applying it on the surface of a microneedle array (MN), which has emerged as a promising POCT device capable of accessing interstitial fluid through minimal penetration of the skin. This PSI-SNP MN is demonstrated to detect a wide array of proteins with high sensitivity on par with conventional whole serum analysis, validated by in vivo animal testing, effectively displaying broad applicability in biomedical engineering.
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Técnicas Biossensoriais , Nanocompostos , Animais , Dióxido de Silício/química , Pele , AgulhasRESUMO
Over the past few decades, extensive research efforts have been devoted to developing surfaces with unique functionalities, such as controlled wettability, antibiofouling, antifogging, and anti-icing behavior, for applications in a wide range of fields, including biomedical devices, optical instruments, microfluidics, and energy conservation and harvesting. However, many of the previously reported approaches have limitations with regard to eco-friendliness, multifunctionality, long-term stability and efficacy, and cost effectiveness. Herein, we propose a scalable bifunctional surface that simultaneously exhibits excellent antifogging and antibiofouling properties based on the synergistic integration of an eco-friendly and bio-friendly polyethylene glycol (PEG) hydrogel, oleamide (OA), and nanoscale architectures in a single flexible platform. We demonstrate that the PEG-OA-nanostructure hybrid exhibits excellent antifogging performance owing to its enhanced water absorption and spreading properties. We further show that the triple hybrid exhibits notable biofilm resistance without the use of toxic biocides or chemicals by integrating the "fouling-resistant" mechanism of the PEG hydrogel, the "fouling-release" mechanism of OA, and the "foulant-killing" mechanism of the nanostructures.
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While 2D transition metal dichalcogenides (TMDs) are promising building blocks for various optoelectronic applications, limitations remain for multilayered TMD-based photodetectors: an indirect bandgap and a short carrier lifetime by strongly bound excitons. Accordingly, multilayered TMDs with a direct bandgap and an enhanced carrier lifetime are required for the development of various optoelectronic devices. Here, periodically arrayed nanopore structures (PANS) are proposed for improving the efficiency of multilayered p-WSe2 /n-MoS2 phototransistors. Density functional theory calculations as well as photoluminescence and time-resolved photoluminescence measurements are performed to characterize the photodetector figures of merit of multilayered p-WSe2 /n-MoS2 heterostructures with PANS. The characteristics of the heterojunction devices with PANS reveal an enhanced responsivity and detectivity measured under 405 nm laser excitation, which at 1.7 × 104 A W-1 and 1.7 × 1013 Jones are almost two orders of magnitude higher than those of pristine devices, 3.6 × 102 A W-1 and 3.6 × 1011 Jones, respectively. Such enhanced optical properties of WSe2 /MoS2 heterojunctions with PANS represent a significant step toward next-generation optoelectronic applications.
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The probing of fundamental photophysics is a key prerequisite for the construction of diverse optoelectronic devices and circuits. To date, though, photocarrier dynamics in 2D materials remains unclear, plagued primarily by two issues: a large exciton binding energy, and the lack of a suitable system that enables the manipulation of excitons. Here, a WSe2 -based phototransistor with an asymmetric split-gate configuration is demonstrated, which is named the "asymmetry field-effect phototransistor" (AFEPT). This structure allows for the effective modulation of the electric-field profile across the channel, thereby providing a standard device platform for exploring the photocarrier dynamics of the intrinsic WSe2 layer. By controlling the electric field, this work the spatial evolution of the photocurrent is observed, notably with a strong signal over the entire WSe2 channel. Using photocurrent and optical spectroscopy measurements, the physical origin of the novel photocurrent behavior is clarified and a room-temperature exciton binding energy of 210 meV is determined with the device. In the phototransistor geometry, lateral p-n junctions serve as a simultaneous pathway for both photogenerated electrons and holes, reducing their recombination rate and thus enhancing photodetection. The study establishes a new device platform for both fundamental studies and technological applications.