Siloxane Hybrid Material-Encapsulated Highly Robust Flexible µLEDs for Biocompatible Lighting Applications.

Flexible micro-light-emitting diodes (f-µLEDs) have been regarded as an attractive light source for the next-generation human-machine interfaces, thanks to their noticeable optoelectronic performances. However, when it comes to their practical utilizations fulfilling industrial standards, there have been unsolved reliability and durability issues of the f-µLEDs, despite previous developments in the high-performance f-µLEDs for various applications. Herein, highly robust flexible µLEDs (f-HµLEDs) with 20 × 20 arrays, which are realized by a siloxane-based organic-inorganic hybrid material (SHM), are reported. The f-HµLEDs are created by combining the f-µLED fabrication process with SHM synthesis procedures (i.e., sol-gel reaction and successive photocuring). The outstanding mechanical, thermal, and environmental stabilities of our f-HµLEDs are confirmed by a host of experimental and theoretical examinations, including a bending fatigue test (105 bending/unbending cycles), a lifetime accelerated stress test (85 °C and 85% relative humidity), and finite element method simulations. Eventually, to demonstrate the potential of our f-HµLEDs for practical applications of flexible displays and/or biomedical devices, their white light emission due to quantum dot-based color conversion of blue light emitted by GaN-based f-HµLEDs is demonstrated, and the biocompatibility of our f-HµLEDs is confirmed via cytotoxicity and cell proliferation tests with muscle, bone, and neuron cell lines. As far as we can tell, this work is the first demonstration of the flexible µLED encapsulation platform based on the SHM, which proved its mechanical, thermal, and environmental stabilities and biocompatibility, enabling us to envisage biomedical and/or flexible display applications using our f-HµLEDs.

Cardiac Manifestations of Coronavirus Disease 2019 (COVID-19): a Multicenter Cohort Study.

BACKGROUND: This study aimed to investigate the cardiac manifestations of coronavirus disease 2019 (COVID-19). METHODS: From February to March 2020, we prospectively and retrospectively enrolled consecutive patients diagnosed with COVID-19. Patient's data such as the demographic characteristics, symptoms, vital signs, laboratory and radiologic findings, electrocardiographic, and echocardiographic data, including the global longitudinal strain (GLS) of both ventricles, were obtained. RESULTS: Forty patients (median age, 58 years; 50% men) were enrolled in the initial analysis. Patients were classified into severe and nonsevere groups based on the current guidelines. The 13 patients in the severe group were significantly older, had a greater prevalence of bilateral pneumonia and leukocytosis, and higher aspartate transaminase levels than patients in the nonsevere group. Patients in the severe group had a slightly lower left ventricular ejection fraction (LVEF) than those in the nonsevere group (median [interquartile range], 61.0% [58.5%, 62.3%] vs. 66.7% [60.6%, 69.8%], P = 0.015). In a subgroup of 34 patients in whom GLS could be analyzed, patients in the severe group had a significantly impaired left ventricular GLS (LVGLS) than those in the nonsevere group (-18.1% [-18.8%, -17.1%] vs. -21.7% [-22.9%, -19.9%], P = 0.001). There were no significant differences in total wall (RVGLStotal, -19.3% [-23.9%, -18.4%] vs. -24.3% [-26.0%, -22.6%], P = 0.060) and free wall (RVGLSfw, -22.7% [-27.2%, -18.6%] vs. -28.8% [-30.4%, -24.1%], P = 0.066) right ventricle GLS (RVGLS). CONCLUSION: Patients with severe COVID-19 had lower LVEF and LVGLS. RVGLS was not different between patients with severe and nonsevere COVID-19.

Patterns of viral clearance in the natural course of asymptomatic COVID-19: Comparison with symptomatic non-severe COVID-19.

OBJECTIVES: The aim of this study was to elucidate patterns of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) clearance in the natural course of asymptomatic coronavirus disease 2019 (COVID-19). METHODS: Consecutive patients with non-severe COVID-19 were included retrospectively. Asymptomatic patients with a normal body temperature and no evidence of pneumonia throughout the disease course were assigned to the asymptomatic group. The reverse transcription PCR (RT-PCR) assay was repeated every two to five days after the first follow-up RT-PCR assay. Negative conversion was defined as two consecutive negative RT-PCR assay results within a 24-h interval. Rebound of the cycle threshold (Ct) value was defined as negative from the single RT-PCR assay and positive from the following assay. RESULTS: Among a total of 396 patients identified (median age 42.5 years (interquartile range (IQR) 25.0-55.0 years), 35.6% male), 68 (17.2%) were assigned to the asymptomatic group and 328 (82.8%) to the symptomatic group. The time until negative conversion was significantly shorter in the asymptomatic group than in the symptomatic group: median 14.5 days (IQR 11.0-21.0 days) and 18.0 days (IQR 15.0-22.0 days), respectively (p = 0.001). Rebound of Ct values was observed in 78 patients (19.7%). CONCLUSIONS: Time until negative conversion is shorter in asymptomatic COVID-19 than in symptomatic COVID-19. Rebound of Ct values is not uncommon.

Photo-Patternable Quantum Dots/Siloxane Composite with Long-Term Stability for Quantum Dot Color Filters.

Incorporation of quantum dots (QDs) into color filters (CFs) are desired for less energy loss and wider viewing angle compared to a conventional display. However, aggregation and vulnerability to heat, moisture, and chemicals in the photo-patternable matrix are critical issues of the QD-CFs with high QDs concentration. Herein, we fabricated red (10 wt %) and green (20 wt %) QD-CFs using photolithography of QD/siloxane ink containing secondary thiol monomer. Ligand-exchanged QDs were chemically incorporated in methacrylate oligosiloxane resin. QD/siloxane composite showed superior stability under harsh heat and moisture (85 °C/5% RH and 85 °C/85% RH) conditions and chemicals (EtOH, HCl, and NaOH) compared to conventional QD/PR (commercial negative photoresist). QD-CFs (10 µm thick) effectively converted blue light emitted from LED chip into red and green light, and the obtained white PL through QD-CF showed wide color gamut, which was 108% relative to NTSC. From these advantages, QD/siloxane composite will be beneficial as color-conversion photoresists are to be used as color filters in liquid crystal displays, micro light-emitting diodes, and organic light-emitting diodes.

Exceptionally stable quantum dot/siloxane hybrid encapsulation material for white light-emitting diodes with a wide color gamut.

Herein, we report a luminescent light-emitting diode (LED) encapsulating material using a thermally curable quantum dot (QD)/siloxane hybrid (TSE-QD) color converter, which has superior long-term stability even at elevated temperatures, in high humidity, and in various chemicals. The TSE-QD is cured by a thermal-induced hydrosilylation reaction of an in situ sol-gel synthesized QD dispersed siloxane resin (QD/siloxane resin) without additional ligand-exchange processes. QDs are successfully encapsulated by highly condensed and linear structured siloxane networks with additional chemical linkages between the surface ligands of the QDs and organic functional groups of the siloxane matrix. Moreover, QDs are uniformly distributed within the siloxane matrix retaining their optical properties during the fabrication processes of the TSE-QD. The result is that the stability, as evaluated by the photoluminescence (PL) quantum yield (QY), is greatly improved under harsh conditions, for example, 120 °C/5% relative humidity (RH), ethanol and acetone for 30 days. Based on the exceptionally stable TSE-QD, we demonstrate a white LED using a blue LED chip directly encapsulated by a yellow emitting TSE-QD that shows excellent spectral stability, outstanding reliability at 85 °C/85% RH and a wide color gamut (116% of NTSC).

Two-Step-Enhanced Stability of Quantum Dots via Silica and Siloxane Encapsulation for the Long-Term Operation of Light-Emitting Diodes.

Despite innovative optical properties of quantum dots (QDs) for QDs-converted light-emitting diodes (QD-LEDs), the vulnerability of the QDs, against heat and moisture, has been a critical issue for commercialization and long-term use. To overcome the instabilities, we fabricated a thermally and photostable QDs-embedded silica/siloxane (S-QD/siloxane) film by embedding QDs in silica and siloxane encapsulation through a two-step sol-gel reaction. S-QDs were stably dispersed in the oligo-siloxane resin with even a QD concentration of 5 wt % without aggregation. The two-step physical barriers of silica and siloxane acted to decrease the toxicity of QDs and improve the stability against heat and moisture [85 °C/5% relative humidity (RH), 85 °C/85% RH, and 120 °C/5% RH], light (50 and 100 mA), and chemicals (ethanol, HCl, and NaOH). Our S-QD/siloxane film was applied as a color-conversion material on a blue LED chip without additional solidification and encapsulation processes for red and white QD-LEDs, exhibiting a wider color gamut (107% in CIE 1931) compared to NTSC. These enhancements indicate that our S-QD/siloxane film is a suitable material for long-term operation of QD-enhanced films and QD-LEDs in next-generation displays.

Meta-analysis of outcomes after intravascular ultrasound-guided versus angiography-guided drug-eluting stent implantation in 26,503 patients enrolled in three randomized trials and 14 observational studies.

There are conflicting data regarding the benefit of intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) over angiography-guided PCI. Since the last meta-analysis was published, several new studies have been reported. We performed a comprehensive meta-analysis to evaluate the clinical impact of IVUS-guided PCI with drug-eluting stent compared with conventional angiography-guided PCI. This meta-analysis included 26,503 patients from 3 randomized and 14 observational studies; 12,499 patients underwent IVUS-guided PCI and 14,004 underwent angiography-guided PCI. Main outcome measures were total mortality, myocardial infarction (MI), stent thrombosis, and target lesion revascularization (TLR). IVUS-guided PCI was significantly associated with more stents, longer stents, and larger stents. Regarding clinical outcomes, IVUS-guided PCI was associated with a significantly lower risk of TLR (odds ratio [OR] 0.81, 95% confidence interval [CI] 0.66 to 1.00, p=0.046). In addition, the risk of death (OR 0.61, 95% CI 0.48 to 0.79, p<0.001), MI (OR 0.57, 95% CI 0.44 to 0.75, p<0.001), and stent thrombosis (OR 0.59, 95% CI 0.47 to 0.75, p<0.001) were also decreased. In conclusion, our meta-analysis demonstrated that IVUS-guided PCI was associated with lower risk of death, MI, TLR, and stent thrombosis after drug-eluting stent implantation.

Dual antiplatelet therapy after drug-eluting stents: defining the proper duration.

As compared with bare-metal stents, drug-eluting stents (DESs) reduce restenosis in every clinical situation and every type of lesion studied. Therefore, DESs have been in widespread use for more than a decade and are used in the majority of patients receiving intracoronary stents. However, several studies have suggested that early discontinuation of dual antiplatelet therapy (DAPT; the combination of aspirin and an inhibitor of platelet P2Y12) is associated with a greater risk for 'late' stent thrombosis in patients with DESs. Because of the relative risk and benefit associated with DESs and the use of DAPT, perhaps the most common question for the treating physicians and patients are with regard to the appropriate duration of DAPT for patients treated with DES implantation. Several observational studies have shown inconsistent findings with respect to the optimal duration of DAPT after DES implantation. Subsequent randomized clinical trials have indicated that courses of clopidogrel exceeding 12 months do not contribute favorably to patient outcomes and may in fact be detrimental. No sound evidence is available to support prolongation of DAPT beyond 12 months. On the basis of recent clinical studies, a shorter course of DAPT than recommended by the guidelines (at least 12 months in the ACCF/AHA/SCAI guideline and 6-12 months in the European Society of Cardiology guidelines) may be considered, especially with second-generation or newer-generation DESs being associated with a significant reduction in stent thrombosis compared with first-generation DES. However, as these trials also had insufficient statistical power to allow for a firm decision with regard to the optimal DAPT duration after DES implantation, the results of larger ongoing clinical trials are necessary to resolve this issue before changing the practice. This article systematically reviews the cumulative evidence from key clinical studies and tries to help guide the physician in making informed decisions on the optimal duration of DAPT for patients who are undergoing DES implantation.