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Two-dimensional (2D) organic–inorganic perovskites have shown interesting optical properties due to the natural quantum-well structures. The repetition of soft organic and hard inorganic intercalations also renders 2D perovskites rich phonon dynamics. Here, we investigated the coherent acoustic phonons in (PEA)2PbI4 perovskite films by time-resolved Brillouin spectroscopy. The coherent acoustic phonons were launched indirectly in perovskite films by exciting Au nanoplates which were used as optoacoustic transducers. A longitudinal sound velocity ν = 1937 ± 31 m/s, and an elastic modulus E = 9.84 GPa along the cross-plane direction of perovskites were obtained from analysis of the Brillouin oscillation frequency. Following a bead-spring model, we calculated a spring constant k ≈ 1.709 N m−1 for PEA cations which is comparably small for perovskites. We also demonstrated that coherent acoustic phonons are sensitive to differentiate structural heterogeneity and monitor dynamic phase evolution in perovskite films. Domains of PbI2-rich and PbI2-poor phases were identified. Under light stimulus, PbI2-poor phases were gradually disappearing and PbI2-rich phases became crystallized. The observations of structural and elastic heterogeneity and dynamic phase evolution using coherent acoustic phonons provide a toolbox for submicroscale elastic characterization of perovskites.

Two-dimensional (2D) materials with excellent optical properties and complementary metal-oxide-semiconductor (CMOS) compatibility have promising application prospects for developing highly efficient, small-scale all-optical modulators. However, due to the weak nonlinear light-material interaction, high power density and large contact area are usually required, resulting in low light modulation efficiency. In addition, the use of such large-band-gap materials limits the modulation wavelength. In this study, we propose an all-optical modulator integrated Si waveguide and single-layer MoS2 with a plasmonic nanoslit, wherein modulation and signal light beams are converted into plasmon through nanoslit confinement and together are strongly coupled to 2D MoS2. This enables MoS2 to absorb signal light with photon energies less than the bandgap, thereby achieving high-efficiency amplitude modulation at 1550 nm. As a result, the modulation efficiency of the device is up to 0.41 dB μm−1, and the effective size is only 9.7 µm. Compared with other 2D material-based all-optical modulators, this fabricated device exhibits excellent light modulation efficiency with a micron-level size, which is potential in small-scale optical modulators and chip-integration applications. Moreover, the MoS2-plasmonic nanoslit modulator also provides an opportunity for TMDs in the application of infrared optoelectronics.

Lung cancer is the most common cause of cancer-related death in the world. Long non-coding RNAs (lncRNAs) are longer than 200 nucleotide transcripts, and are not translated into protein. The lncRNA linc00662 is overexpressed in lung cancer; however, its role in lung cancer is still unknown. In our study, by analyzing the TCGA data, we found that linc00662 was overexpressed in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). We knocked-down the expression of linc00662 using siRNA, and found that silencing linc00662 significantly inhibited the proliferation and colony formation of the lung cancer cell lines A549 and H460. We also found that knockdown of linc00662 increased the expression of the microRNA miR-145-5p and decreased the expression of the platelet-activating factor acetylhydrolase IB subunit beta (PAFAH1B2) gene. We further show that linc00662 binds with miR-145-5p, and that miR-145-5p binds to the 3'UTR of PAFAH1B2. miR-145-5p negatively regulates PAFAH1B2 both at the mRNA and the protein level. Loss of miR-145-5p abolished the inhibitory effects of silencing linc00662 on the proliferation and colony formation of A549 and H460 cells. These findings indicate that linc00662 functions as an oncogene by acting as a competing endogenous RNA (ceRNA) and sponges and regulates miR-145-5p in lung cancer, and thus may provide a potential target for treating lung cancer. Key words: linc00662, PAFAH1B2, miR-145-5p, proliferation, colony formation, lung cancer. Le cancer du poumon est la cause la plus fréquente de décès liés au cancer dans le monde. Les longs ARN non codants (lncARN) sont des transcrits de plus de 200 nucléotides qui ne sont pas traduits en protéines. Le linc00662 est surexprimé dans le cancer du poumon. Cependant, le rôle du linc00662 dans la progression du cancer du poumon est encore inconnu. Dans cette étude, les auteurs ont découvert que le linc00662 était surexprimé dans l'adénocarcinome du poumon et le carcinome épidermoïde du poumon en analysant les données de l'atlas TCGA. Ils ont réduit par knockdown l'expression du linc00662 en utilisant des ARNsi et découvert que le silençage du linc00662 inhibait de manière significative la prolifération et la formation de colonies des cellules A549 et H460. Ils ont également découvert que le knockdown du linc00662 accroissait l'expression du miR-145-5p et diminuait l'expression de PAAFAAH1B2 (platelet-activating factor acetylhydrolase IB subunit beta). Ils ont aussi montré que le linc00662 pouvait se lier au miR-145-5p, et que le miR-145-5p pouvait se lier à l'extrémité 3'UTR de PAFAH1B2. Le miR-145-5p pouvait réguler négativement PAFAH1B2 au niveau de l'ARNm et de la protéine. La perte du miR-145-5p pouvait abolir les effets inhibiteurs du silençage du linc00662 sur la prolifération et la formation de colonies des cellules A549 et H460. Toutes ces données ont montré que le linc00662 fonctionnait comme un oncogène en agissant comme un ARN endogène compétitif (ARNce) pour capturer et réguler le miR-145-5p dans le cancer du poumon et qu'il pourrait constituer une cible potentielle pour le traitement du cancer du poumon. [Traduit par la Rédaction.] Mots-clés : linc00662, PAFAH1B2, miR-145-5p, prolifération, formation de colonies, cancer du poumon., Introduction Lung cancer is the leading cause of cancer-related death in the world. Although progress has been made in the treatment of lung cancer, the survival of patients with lung [...]

Hyperbolic phonon polaritons in optically uniaxial hexagonal boron nitride (hBN) have shown considerable potential for manipulating light on the deep‐subwavelength scale, but the inherent in‐plane isotropy of hBN hinders their further application in planar polariton meta‐optics. Engineering these polaritons to achieve ultraconfined in‐plane anisotropic propagation is of scientific significance for facilitating light–matter interactions toward an extreme scale. Here, the polariton features are systematically investigated in a vertically stacked van der Waals heterostructure consisting of hBN and tellurium (Te), a highly birefringent van der Waals crystal in the mid‐infrared region. Polaritons in this heterostructure exhibit Te‐thickness‐dependent anisotropic dispersion, and the configurable in‐plane anisotropy and enhanced field confinement are experimentally demonstrated using scanning near‐field optical microscopy. It is concluded that these findings contribute to the fundamental understanding of anisotropic polaritons in hBN van der Waals heterostructures, providing a practical avenue for effectively engineering anisotropic PhPs in an intrinsically isotropic van der Waals material. [ABSTRACT FROM AUTHOR]

Incorporating dispersion into time-varying media not only holds practical significance but also profoundly transforms the electromagnetic characteristics of such dynamic media. In this work, we have developed a temporal transfer matrix method (TTMM) tailored for time-varying media exhibiting a specific type of dispersion, namely, Lorentzian dispersion. The conventional TTMM for nondispersive time-varying media can be regarded as an approximation of this developed TTMM in the nondispersive limit by ignoring the unobservable infinite-frequency modes. By using this developed TTMM, we have investigated the Floquet bands of Lorentzian dispersive media with time-periodic plasmon frequencies or resonant frequencies. Under temporal modulations, certain degenerate points of the Floquet bands will be lifted, creating bandgaps, while others will give rise to two types of exceptional point (EP) pairs. This sharply contrasts with the well-known Floquet bands of nondispersive time-varying media, where only one type of EP pair exists. Our developed TTMM serves as a powerful tool for investigating the phenomena within the realm of dispersive time-varying media. [ABSTRACT FROM AUTHOR]

Subtle responsive properties can be achieved by the photonic crystal (PC) nanostructures of butterfly based on thermal expansion effect. The studies focused on making the sample visually distinct. However, the response is restricted by limited thermal expansion coefficients. We herein report a new class of reversible thermochromic response achieved by controlling the ambient refractive index in butterfly PC structure. The photonic ethanol-filled nanoarchitecture sample is simply assembled by sealing liquid ethanol filling Papilio ulysses butterfly wing. Volatile ethanol is used to modulate the ambient refractive index. The sample is sealed with glasses to ensure reversibility. Liquid ethanol filling butterfly wing demonstrated significant allochroic response to ambient refractive index, which can be controlled by the liquefaction and vaporization of ethanol. This design is capable of converting thermal energy into visual color signals. The mechanism of this distinct response is simulated and proven by band theory. The response properties are performed with different filled chemicals and different structure parameters. Thus, the reversible thermochromic response design might have potential use in the fields such as detection, photonic switch, displays, and so forth.

Metal nanoparticles are excellent acoustic resonators and their vibrational spectroscopy has been widely investigated. However, the coupling between vibrational modes of different nanoparticles is less explored. For example, how the intervening medium affects the coupling strength is not known. Here, we investigate how different polymers affect coupling in Au nanoplate–polymer–Au nanoplate sandwich structures. The coupling between the breathing modes of the Au nanoplates was measured using single-particle pump–probe spectroscopy, and the polymer dependent coupling strength was determined experimentally. Analysis of the acoustic mode coupling gives the effective spring constant for the polymers. A relative motion mode was also observed for the stacked Au nanoplates. The frequency of this mode is strongly correlated with the coupling constant for the breathing modes. The breathing mode coupling and relative motion mode were analyzed using a coupled oscillator model. This model shows that both these effects can be described using the same spring constant for the polymer. Finally, we present a new type of mass balance using the strongly coupled resonators. We show that the resonators have a mass detection limit of a few femtograms. We envision that further understanding of the vibrational coupling in acoustic resonators will improve the coupling strength and expand their potential applications. [ABSTRACT FROM AUTHOR]

Lead halide perovskite quantum dots (PQDs) are widely regarded as promising materials for various display and lighting applications due to their exceptional optical properties, including high photoluminescence quantum yields and saturated color purity. However, the full potential of industrial and daily applications of PQDs in large-area and highly stable displays has not yet been adequately exploited. In this study, we achieved natural light anticounterfeiting (visible under UV excitation) and passive displays by uniformly and nondestructively incorporating precrystallized colloidal PQDs into a poly-(methyl methacrylate) (PMMA) matrix. PMMA long chains provide structural support and passivation for PQDs. In instances where surface organic chains are disrupted or removed by external stimuli, these long chains play a pivotal role in preventing deformations and aggregations, consequently enhancing the resistance to water, heat, and photoirradiation stimuli. The encapsulation of PQDs with sufficient PMMA long chains allows for the retention of fluorescence without any deterioration for over 6 weeks. Furthermore, the flexibility and mechanical properties of the PMMA matrix enable a variety of processing on these PQD–PMMA membranes, resulting in diverse display applications behaving with both practical and aesthetic advantages. Our research findings open up new possibilities for expanding the range of display applications for PQDs. [ABSTRACT FROM AUTHOR]

Near-infrared light (NIR) has the advantages of greater radiation depth, less tissue absorption and scattering, and lower risk, and the construction of a high-throughput NIR responsive membrane with ionic current rectification (ICR) characteristics in submicron or micron channels is of great significance for developing photoresponsive biosensors, and photoelectric and thermoelectric energy conversion in the future. In this paper, sulfhydryl- and carboxyl-terminated poly-N-isopropyl acrylamide with thermosensitivity is synthesized by a reversible addition–fragmentation chain transfer polymerization and ammonolysis reaction; it is further grafted at the base end of a polydopamine/Au nanoparticle-modified photothermal responsive heterogeneous membrane via a Au–S bond to achieve the thermosensitive polymer modification. After the asymmetric 808 nm NIR irradiation, the "on" or "off" status of a submicron channel can be realized stably and reversibly for the reversible phase transition of thermosensitive poly-N-isopropyl acrylamide under the photothermal effect of three polydopamine-Au layers. The conductance of the submicro-channel heterogeneous membrane with ICR characteristics increases at the asymmetric pH gradient, the rectification ratio maximally decreases by 11.4, and the photoresponsive current reaches 26.6 μA (0.1 mM KCl). At the same time, the ICR effect is also achieved at a high salt concentration of 1 M KCl and the photoresponsive current can reach 183.7 μA; the intensity of ICR and photoresponsive current can be effectively regulated by the power density, salt concentration and pH, and then the temperature-sensing switch with a NIR response is successfully constructed. This work provides a new way to improve the photoresponsive current and shows great potential in the fields of solar desalination and power generation. [ABSTRACT FROM AUTHOR]

The self‐trapped excitons (STEs) in soft van der Waals (vdW) materials have aroused tremendous attention. The conventional methods to manipulate the STEs include the introduction of permanent defect or lattice distortion, which lead to the suppression of the inherent structures and properties. Developing a non‐destructive method to achieve room temperature STEs with high tunability is thus of strategic interest. Stacking 2D materials to form a vdW heterostructure will introduce many‐body interactions, which should be exploited to tailor STE emissions controllably. To this regard, the highly tunable STE emissions in vdW heterostructures composed of lead iodide, hexagonal boron nitride, or molybdenum oxide are demonstrated. It is found that the synergistic effect of the dielectric screening and interfacial many‐body interaction improve the temperature characteristic and emission properties of STEs. The strong STE emissions with highly tunable center energies in a broadband spectrum range from ≈625 to 750 nm are verified at room temperature. This work provides a non‐destructive method to manipulate the STE emissions at room temperature in rigid lattice vdW materials, which is expected to open the potential of STEs for next‐generation optoelectronics. [ABSTRACT FROM AUTHOR]