Dioxane promoted photochemical O-alkylation of 1,3-dicarbonyl compounds beyond carbene insertion into C-H and C-C bonds.

A photochemical synthesis of enol ethers and furan-3(2H)-ones from 1,3-dicarbonyl compounds and aryl diazoacetates has been developed. Significantly, 1,4-dioxane promoted O-alkylation of various 1,3-dicarbonyl compounds beyond previous carbene insertion into C-H and C-C bonds has been disclosed.

Exploring the measurement of psychological resilience in Chinese civil aviation pilots based on generalizability theory and item response theory.

Understanding and accurately measuring resilience among Chinese civil aviation pilots is imperative, especially concerning the psychological impact of distressing events on their well-being and aviation safety. Despite the necessity, a validated and tailored measurement tool specific to this demographic is absent. Addressing this gap, this study built on the widely used CD-RISC-25 to analyze and modify its applicability to Chinese civil aviation pilots. Utilizing CD-RISC-25 survey data from 231 Chinese pilots, correlational and differential analyses identified items 3 and 20 as incongruent with this population's resilience profile. Subsequently, factor analysis derived a distinct two-factor resilience psychological framework labeled "Decisiveness" and "Adaptability", which diverged from the structure found in American female pilots and the broader Chinese populace. Additionally, to further accurately identify the measurement characteristics of this 2-factor measurement model, this study introduced Generalized Theory and Item Response Theory, two modern measurement analysis theories, to comprehensively analyze the overall reliability of the measurement and issues with individual items. Results showed that the 2-factor model exhibited high reliability, with generalizability coefficient reaching 0.89503 and dependability coefficient reaching 0.88496, indicating the 2-factor measurement questionnaire can be effectively utilized for relative and absolute comparison of Chinese civil aviation pilot resilience. However, items in Factor 2 provided less information and have larger room for optimization than those in Factor 1, implying item option redesign may be beneficial. Consequently, this study culminates in the creation of a more accurate and reliable two-factor psychological resilience measurement tool tailored for Chinese civil aviation pilots, while exploring directions for optimization. By facilitating early identification of individuals with lower resilience and enabling the evaluation of intervention efficacy, this tool aims to positively impact pilot psychological health and aviation safety in the context of grief and trauma following distressing events.

Base-free regio- and stereoselective photochemical synthesis of enol ethers from 1,3-dicarbonyl compounds.

A visible light-induced kinetic controlled regioselective O-alkylation of various 1,3-dicarbonyl compounds with diazoacetates and cyclic ethers has been developed. The protocol provides a green and practical approach to highly stereoselective enol ethers under mild and base-free conditions in good to excellent yields.

Fano Resonance in Near-Field Thermal Radiation of Two-Dimensional Van der Waals Heterostructures.

Two-dimensional (2D) materials and their vertically stacked heterostructures have attracted much attention due to their novel optical properties and strong light-matter interactions in the infrared. Here, we present a theoretical study of the near-field thermal radiation of 2D vdW heterostructures vertically stacked of graphene and monolayer polar material (2D hBN as an example). An asymmetric Fano line shape is observed in its near-field thermal radiation spectrum, which is attributed to the interference between the narrowband discrete state (the phonon polaritons in 2D hBN) and a broadband continuum state (the plasmons in graphene), as verified by the coupled oscillator model. In addition, we show that 2D van der Waals heterostructures can achieve nearly the same high radiative heat flux as graphene but with markedly different spectral distributions, especially at high chemical potentials. By tuning the chemical potential of graphene, we can actively control the radiative heat flux of 2D van der Waals heterostructures and manipulate the radiative spectrum, such as the transition from Fano resonance to electromagnetic-induced transparency (EIT). Our results reveal the rich physics and demonstrate the potential of 2D vdW heterostructures for applications in nanoscale thermal management and energy conversion.

Thermal Insulation Performance of Aerogel Nano-Porous Materials: Characterization and Test Methods.

Due to the extremely high porosity and extremely low density of nano-porous thermal insulation materials, the characteristic size of the pores inside the materials and the characteristic size of the solid skeleton structure are on the nanometer scale, which leads to the obvious nanoscale effect of the heat transfer law inside the aerogel materials. Therefore, the nanoscale heat transfer characteristics inside the aerogel materials and the existing mathematical models for calculating the thermal conductivity of various heat transfer modes at the nanoscale need to be summarized in detail. Moreover, in order to verify the accuracy of the thermal conductivity calculation model of aerogel nano-porous materials, correct experimental data are required to modify the model. Because the medium is involved in radiation heat transfer, the existing test methods have a large error, which brings great difficulties to the design of nano-porous materials. In this paper, the heat transfer mechanism, characterization methods, and test methods of thermal conductivity of nano-porous materials are summarized and discussed. The main contents of this review are as follows. The first part introduces the structural characteristics and specific application environment of aerogel. In the second part, the characteristics of nanoscale heat transfer of aerogel insulation materials are analyzed. In the third part, the characterization methods of thermal conductivity of aerogel insulation materials are summarized. In the fourth part, the test methods of thermal conductivity of aerogel insulation materials are summarized. The fifth part gives a brief conclusion and prospect.

Influencing factors of novice pilot SA based on DEMATEL-AISM method: From pilots' view.

Pilot situation awareness (SA) regulates flight safety, and inexperience may impair novice pilot reliability in SA. This study aims to determine the key influencing factors of novice pilot SA and to analyze the interrelationship and interaction mechanism of the factors. We investigated 55 novice pilots trained at aviation schools and identified the influencing factor index system by the Delphi survey. The method of Decision Making Trial and Evaluation (DEMATEL) combined with Adversarial Interpretive Structure Modeling (AISM) was adopted. The results show that: (1) The influencing factor index system includes 18 factors, divided into four categories: individual factors, team factors, task and human-machine system factors, and cockpit environment factors. (2) Team communication, team cooperation, basic cognitive ability, interface design, occupational age and experience, and authority gradient are the six crucial influencing factors. The former three have the greatest association with other factors, while the latter three are most likely to affect other factors. (3) Team communication, basic cognitive ability, and interface design are root-cause factors, of which team communication is the most fundamental. (4) The results of DEMATEL and AISM are consistent, both disclosing team communication as the fundamental factor with the highest priority, and cockpit environmental factors as the direct influencing factors but most susceptible to other factors. The present study can be viewed as a conducive attempt to extract vital influencing factors of novice pilot SA, and to provide ergonomic insights for determining the priorities to improve novice pilot SA in training and aircraft design for flight safety.

Visible light-induced carbene reactivity of acceptor diazoalkanes: deconstructive difunctionalizations of cyclic ethers with nucleophiles.

A visible light-induced carbene reactivity of acceptor diazoalkanes has been developed for the synthesis of difunctionalized ethers from cyclic ethers and various N/O/S nucleophiles.

Photocatalytic Regioselective Difunctionalization of Alkenes with Diazo Compounds and tert-Butyl Nitrite: Access to γ-Oximino Esters.

A visible-light photocatalytic regioselective difunctionalization of alkenes with diazo compounds and tert-butyl nitrite has been developed. The protocol provides an efficient approach to γ-oximino esters under mild conditions. Significantly, this transformation not only shows the good compatibility of nucleophilic diazo compounds and electrophilic tert-butyl nitrite but also displays diazo compounds generating alkyl radicals that preferred addition to alkenes over nitroso radicals.

Visible Light-Promoted Diazoacetates and Nitriles Generating Nitrilium Ions Trapped by Benzotriazoles and Carboxylic Acids.

A visible light-promoted generation of nitrilium ions from diazoacetates and nitriles has been developed. The reaction utilized visible light transformation of diazoacetates to the free carbene that could be trapped by nitriles to generate nitrilium ions, followed by nucleophilic attack on the benzotriazoles and carboxylic acids. This protocol provides an efficient and practical approach to N-imidoylbenzotriazoles and diacylglycine esters in good to excellent yields.

Numerical Study of the Influence of Coupling Interface Emissivity on Aerogel Metal Thermal Protection Performance.

For aerogels in metal thermal protection system (MTPS), radiative heat transfer will participate in the thermal transport process. Therefore, the influence of the emissivity of the coupling interface between metal and aerogels on thermal insulation performance is considered an important research focus. In this paper, CFD numerical simulation is performed to study the influence of emissivity on the performance with different extinction coefficients at different boundary temperatures. The finite volume method and the discrete ordinate method are used to solve the govern equations. The results show that when the boundary temperatures are 600 K and 2100 K, the extinction coefficient is 50 m-1, and the reduction percentage of the effective thermal conductivity with an emissivity of 0.2 can be up to 47.5% and 69.8%, compared to the system with an emissivity of 1. Thus, the reduction in emissivity has a good effect on the thermal insulation performance of the MTPS at a higher boundary temperature for materials with small extinction coefficients.

Merging Gold/Copper Catalysis and Copper/Photoredox Catalysis: An Approach to Alkyl Oxazoles from N-Propargylamides.

Here, we report a mild and highly efficient approach to alkyl oxazoles through merging gold/copper catalysis and copper/photoredox catalysis. Various alkyl oxazoles are synthesized from N-propargylamides with alkyl halides in good to excellent yields with wide functional-group compatibility under blue-light irradiation. Significantly, a copper catalyst plays a dual role in this transformation: as a powerful cocatalyst to accelerate protodeauration of vinyl gold intermediates and improve photoredox catalysis.

Geometrical effect of graded index on the transport of polarized lights.

We investigate the geometrical effect of graded index on the transport of polarized lights in the scope of geometrical optics, and present three effective methods based on the Runge-Kutta ray tracing technique in the Frenet-Serret frame and a fixed global Cartesian frame, respectively, for obtaining the polarization state of a polarized light that propagates in graded-index media. The three methods have their own advantages in accuracy, computational efficiency, and difficulty of implementation, respectively. Simulations on a three-dimensional graded-index model show that the results obtained by the three methods are in perfect agreement with each other.

Symmetric metasurface with dual band polarization-independent high-Q resonances governed by symmetry-protected BIC.

In this Letter, we propose a symmetric metasurface composed of single-sized amorphous-silicon (a-Si) cuboids tetramer clusters that support two resonances with opposite symmetry, i.e., in-plane magnetic dipole (MD) resonance and in-plane toroidal dipole (TD) resonance governed by symmetry-protected bound states in the continuum (SP-BIC) in the near-infrared region. Since the cuboids tetramer of the metasurface retains C4v symmetry and mirror symmetry, both resonances are polarization independent. Multipolar decomposition of scattering power and electromagnetic distribution are performed to clarify the physical mechanism of dual quasi-BIC resonances. The effects of geometric parameters on both high-quality (Q) resonances are also studied. Additionally, the sensing performance of the designed metasurface is evaluated. The effects of the material's loss on both resonances are also studied. Our work provides a new route to designing dual mode polarization- independent resonators without multi-sized complex structures that may facilitate designing high-performance sensing applications.

Direction-independent dual-band perfect absorption induced by fundamental magnetic polaritons.

In this paper, we designed a single sized Metal-Insulator Pair-Metal hybrid grating for dual-band perfect absorption from 8 µm to 14 µm utilizing both nondispersive insulators and dispersive phonic insulators. The hybrid grating was composed of Al/ZnTe-SiC pair/Al, which incorporated an ultrathin phononic SiC layer between the nondispersive ZnTe dielectric spacer and Al substrate. The physical mechanisms responsible for the dual-band perfect absorption were elucidated by the resonance of fundamental magnetic polaritons (MPs). Dual-band perfect absorption with incident angle insensitive feature was enabled. An equivalent LC circuit model predicting the dual-band resonant absorption peaks wavelengths was proposed and verified. Furthermore, the effects of grating period, strip width, nondispersive dielectric spacer thickness and polar phononic dielectric spacer thickness on the absorption were explored.

Near-field radiative transfer between magneto-dielectric uniaxial anisotropic media.

We investigate the near-field radiative heat transfer between two semi-infinite magneto-dielectric uniaxial anisotropic media (MDUAM). SiC nanowires embedded in metamaterials are used to implement electric and magnetic anisotropy, which leads to the hyperbolic dispersion relation for both TE and TM waves. The results show that the TM and TE waves can support both hyperbolic modes and surface modes and that there exist additional modes contributing to the heat transfer for TE waves. Moreover, the MDUAM exhibit super-Planckian thermal emission at ultra-broad bandwidths. This work paves the way for applying the near-field radiative heat transfer in the area of thermal management and energy harvesting.