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Background: Although cumulative studies have demonstrated a beneficial effect of high-flow nasal cannula oxygen (HFNC) in acute hypercapnic respiratory failure, randomized trials to compare HFNC with non-invasive ventilation (NIV) as initial treatment in acute exacerbations of chronic obstructive pulmonary disease (AECOPD) patients with acute-moderate hypercapnic respiratory failure are limited. The aim of this randomized, open label, non-inferiority trial was to compare treatment failure rates between HFNC and NIV in such patients. Methods: Patients diagnosed with AECOPD with a baseline arterial blood gas pH between 7.25 and 7.35 and PaCO2 ≥ 50 mmHg admitted to two intensive care units (ICUs) at a large tertiary academic teaching hospital between March 2018 and December 2022 were randomly assigned to HFNC or NIV. The primary endpoint was the rate of treatment failure, defined as endotracheal intubation or a switch to the other study treatment modality. Secondary endpoints were rates of intubation or treatment change, blood gas values, vital signs at one, 12, and 48 h, 28-day mortality, as well as ICU and hospital lengths of stay. Results: 225 total patients (113 in the HFNC group and 112 in the NIV group) were included in the intention-to-treat analysis. The failure rate of the HFNC group was 25.7%, while the NIV group was 14.3%. The failure rate risk difference between the two groups was 11.38% (95% CI 0.25–21.20, P = 0.033), which was higher than the non-inferiority cut-off of 9%. In the per-protocol analysis, treatment failure occurred in 28 of 110 patients (25.5%) in the HFNC group and 15 of 109 patients (13.8%) in the NIV group (risk difference, 11.69%; 95% CI 0.48–22.60). The intubation rate in the HFNC group was higher than in the NIV group (14.2% vs 5.4%, P = 0.026). The treatment switch rate, ICU and hospital length of stay or 28-day mortality in the HFNC group were not statistically different from the NIV group (all P > 0.05). Conclusion: HFNC was not shown to be non-inferior to NIV and resulted in a higher incidence of treatment failure than NIV when used as the initial respiratory support for AECOPD patients with acute-moderate hypercapnic respiratory failure. Trial registration: chictr.org (ChiCTR1800014553). Registered 21 January 2018, http://www.chictr.org.cn [ABSTRACT FROM AUTHOR]

Active control of the surface-enhanced Raman scattering (SERS) enhancement shows great potential for realizing smart detection of different molecules. However, conventional methods usually involve time-consuming structural design or a sophisticated fabrication process. Herein, we reported an electrically tunable field effect transistor (FET) comprising a WOx/MoOx hybrid as the SERS active layer. In the experiment, WOx/MoOx hybrids were first prepared by mixing different molar ratios of WOx and MoOx oxides. Then, R6G molecules were used as Raman reporters, showing that the intensity of the SERS signal observed on the most optimal hybrids (molar ratio = 1 : 3) could be increased by two times as high as that observed on a single WOx or MoOx based substrate, which was ascribed to enhanced charge transfer efficiency by the constructed nano-heterojunction between the WOx and MoOx oxides. Thereafter, a back-gate FET was fabricated on a SiO2/Si substrate, and the most optimal WOx/MoOx hybrid was deposited as the gate channel and the SERS active layer. After that, a series of gate biases (from −15 V to 15 V) were implemented to actively tune the SERS performance of the FET. It is evident that the SERS EF can be further tuned from 2.39 × 107 (−15 V) to 6.55 × 107 (+10 V), which is ∼7.4/4.1 times higher than that observed on the pure WOx device (8.81 × 106) or pure MoOx (1.61 × 107) device, respectively. Finally, the mechanism behind the electrical tuning strategy was investigated. It is revealed that a positive voltage would bend the conduction band down, which increased the electron density near the Fermi level. Consequently, it triggered the resonance charge transfer and significantly improved the SERS performance. In contrast, a negative gate voltage attracted the holes to the Fermi level, which deferred the charge transfer process, and caused the reduction of the SERS enhancement. [ABSTRACT FROM AUTHOR]

Active control of the surface-enhanced Raman scattering (SERS) enhancement shows great potential for realizing smart detection of different molecules. However, conventional methods usually involve time-consuming structural design or a sophisticated fabrication process. Herein, we reported an electrically tunable field effect transistor (FET) comprising a WO x /MoO x hybrid as the SERS active layer. In the experiment, WO x /MoO x hybrids were first prepared by mixing different molar ratios of WO x and MoO x oxides. Then, R6G molecules were used as Raman reporters, showing that the intensity of the SERS signal observed on the most optimal hybrids (molar ratio = 1 : 3) could be increased by two times as high as that observed on a single WO x or MoO x based substrate, which was ascribed to enhanced charge transfer efficiency by the constructed nano-heterojunction between the WO x and MoO x oxides. Thereafter, a back-gate FET was fabricated on a SiO 2 /Si substrate, and the most optimal WO x /MoO x hybrid was deposited as the gate channel and the SERS active layer. After that, a series of gate biases (from -15 V to 15 V) were implemented to actively tune the SERS performance of the FET. It is evident that the SERS EF can be further tuned from 2.39 × 10 7 (-15 V) to 6.55 × 10 7 (+10 V), which is ∼7.4/4.1 times higher than that observed on the pure WO x device (8.81 × 10 6 ) or pure MoO x (1.61 × 10 7 ) device, respectively. Finally, the mechanism behind the electrical tuning strategy was investigated. It is revealed that a positive voltage would bend the conduction band down, which increased the electron density near the Fermi level. Consequently, it triggered the resonance charge transfer and significantly improved the SERS performance. In contrast, a negative gate voltage attracted the holes to the Fermi level, which deferred the charge transfer process, and caused the reduction of the SERS enhancement.

Nonlinear photonic crystals (NPCs) are microstructures characterized by a spatially modulated second-order nonlinear coefficient that have been extensively used for the generation and beam-shaping of coherent light at new frequencies. NPCs for asymmetric optical transmission have a significant impact on novel and multifunction photonic devices. However, nonreciprocal NPCs capable of completely independent asymmetric holographic imaging for the opposite propagation directions have not been reported. Here, we propose a holographic combiner for a different independent image generation at the second-harmonic (SH) wavelength when illuminated from opposite sides of NPCs. The design of the holographic combiner is based on a 3D nonlinear detour phase holography and an orbital angular momentum (OAM) multiplexing nonlinear holography. This work achieves completely independent asymmetric holographic imaging at the SH frequency by using NPCs, which may have potential applications in classical and quantum optical devices.