Transition‐metal dichalcogenides (TMDCs) are an important class of two‐dimensional (2D) layered materials for electronic and optoelectronic applications, due to their ultimate body thickness, sizable ...and tunable bandgap, and decent theoretical room‐temperature mobility. So far, however, all TMDCs show much lower mobility experimentally because of the collective effects by foreign impurities, which has become one of the most important limitations for their device applications. Here, taking MoS2 as an example, the key factors that bring down the mobility in TMDC transistors, including phonons, charged impurities, defects, and charge traps, are reviewed. A theoretical model that quantitatively captures the scaling of mobility with temperature, carrier density, and thickness is introduced. By fitting the available mobility data from literature over the past few years, one obtains the density of impurities and traps for a wide range of transistor structures. It shows that interface engineering can effectively reduce the impurities, leading to improved device performances. For few‐layer TMDCs, the lopsided carrier distribution is analytically modeled to elucidate the experimental increase of mobility with the number of layers. From our analysis, it is clear that the charge transport in TMDC samples is a very complex problem that must be handled carefully.
Transition‐metal dichalcogenides (TMDCs) are widely investigated for enhanced characteristics for electronics among next generation semiconductors. The understanding of charge transport in TMDCs is significant for further device applications. Through carefully analyzing the reported high performance MoS2 devices, this review provides a systematic theoretical and experimental path to optimize the device structure and improve device performance.
Noble metal nanoparticles are promising catalysts in electrochemical reactions, while understanding the relationship between the structure and reactivity of the particles is important to achieve ...higher efficiency of electrocatalysis, and promote the development of single‐molecule electrochemistry. Electrogenerated chemiluminescence (ECL) was employed to image the catalytic oxidation of luminophore at single Au, Pt, and Au‐Pt Janus nanoparticles. Compared to the monometal nanoparticles, the Janus particle structure exhibited enhanced ECL intensity and stability, indicating better catalytic efficiency. On the basis of the experimental results and digital simulation, it was concluded that a concentration difference arose at the asymmetric bimetallic interface according to different heterogeneous electron‐transfer rate constants at Au and Pt. The fluid slip around the Janus particle enhanced local redox reactions and protected the particle surface from passivation.
Electrocatalytic oxidation of a luminophore at single Au, Pt, and Au‐Pt Janus nanoparticles was studied using electrogenerated chemiluminescence (ECL) microscopy. Compared to the monometal nanoparticles, the Janus particle structure exhibited enhanced ECL intensity and stability, indicating better catalytic efficiency.
SUMMARY
Plant cells possess a two‐layered immune system consisting of pattern‐triggered immunity (PTI) and effector‐triggered immunity (ETI), mediated by cell surface pattern‐recognition receptors ...and intracellular nucleotide‐binding leucine‐rich repeat receptors (NLRs), respectively. The CONSTITUTIVE EXPRESSION OF PR GENES 5 (CPR5) nuclear pore complex protein negatively regulates ETI, including ETI‐associated hypersensitive response. Here, we show that CPR5 is essential for the activation of various PTI responses in Arabidopsis, such as resistance to the non‐adapted bacterium Pseudomonas syringae pv. tomato DC3000 hrcC‐. In a forward‐genetic screen for suppressors of cpr5, we identified the mediator protein MED4. Mutation of MED4 in cpr5 greatly restored the defective PTI of cpr5. Our findings reveal that CPR5 plays opposite roles in regulating PTI and ETI, and genetically regulates PTI via MED4.
The Arabidopsis nuclear pore complex protein CPR5 plays a positive role in pattern‐triggered immunity, in contrast to its reported negative role in effector‐triggered immunity. A forward genetic screen for suppressors of cpr5 identified the mediator complex protein MED4; CPR5 regulates pattern‐triggered immunity via MED4.
Plasmon-free surface enhanced Raman scattering (SERS) based on the chemical mechanism (CM) is drawing great attention due to its capability for controllable molecular detection. However, in ...comparison to the conventional noble-metal-based SERS technique driven by plasmonic electromagnetic mechanism (EM), the low sensitivity in the CM-based SERS is the dominant barrier toward its practical applications. Herein, we demonstrate the 1T′ transition metal telluride atomic layers (WTe2 and MoTe2) as ultrasensitive platforms for CM-based SERS. The SERS sensitivities of analyte dyes on 1T′-W(Mo)Te2 reach EM-comparable ones and become even greater when it is integrated with a Bragg reflector. In addition, the dye fluorescence signals are efficiently quenched, making the SERS spectra more distinguishable. As a proof of concept, the SERS signals of analyte Rhodamine 6G (R6G) are detectable even with an ultralow concentration of 40 (400) fM on pristine 1T′-W(Mo)Te2, and the corresponding Raman enhancement factor (EF) reaches 1.8 × 109 (1.6 × 108). The limit concentration of detection and the EF of R6G can be further enhanced into 4 (40) fM and 4.4 × 1010 (6.2 × 109), respectively, when 1T′-W(Mo)Te2 is integrated on the Bragg reflector. The strong interaction between the analyte and 1T′-W(Mo)Te2 and the abundant density of states near the Fermi level of the semimetal 1T′-W(Mo)Te2 in combination gives rise to the promising SERS effects by promoting the charge transfer resonance in the analyte-telluride complex.
Acoustic metamaterials with artificial microstructures are attractive to realize intriguing functions, including efficient waveguiding, which requires large impedance mismatches to realize total side ...reflection with negligible transmission and absorption. While large impedance mismatch can be readily realized in an air environment, acoustic waveguiding in an underwater environment remains elusive due to insufficient impedance mismatch of state‐of‐the‐art metamaterials. Here, a superhydrophobic acoustic metasurface of microstructured poly(vinylidene fluoride) membrane, referred to as a “meta‐skin” insulator, which is able to confine acoustic waves in an all‐angle and wide spectrum range due to tremendous impedance mismatch at stable air/water interfaces, viz., the Cassie–Baxter state is demonstrated. By utilizing the meta‐skin insulator with broadband and high throughput, orbital‐angular‐momentum multiplexing at a high spectral efficiency and binary coding along large‐angle bending channels for bit‐error‐free acoustic data transmission in an underwater environment are demonstrated. Very different from optical and/or electrical cable communications, acoustic waves can be simply and effectively coupled into remote meta‐skin acoustic fibers from free space, which is technologically significant for long‐haul and anti‐interference communication. This work can enlighten many fluidic applications based on efficient waveguiding, such as in vivo ultrasound medical treatment and imaging.
Underwater acoustic wave confinement in an all‐angle and wide spectrum range can be realized in a meta‐skin insulator due to the tremendous impedance mismatch originating from the stable Cassie–Baxter state. Acoustic‐wave‐based underwater orbital‐angular‐momentum multiplexing and binary coding are implemented, which is promising for long‐haul and anti‐interference communication. This work also benefits in vivo ultrasound medical treatment and imaging.
Epitaxially grown ultrathin organic semiconductors on graphene show great promise as highly efficient phototransistors. The devices exhibit a strong photoresponse down to the limit of a monolayer ...organic crystal, with a photoresponsivity higher than 104 A W−1 and a photoconductive gain over 108. The excellent performance is attributed to the high quality of the organic crystal and interface, a unique feature of van der Waals epitaxy.
The uniaxial fatigue and ratcheting behavior of commercial pure titanium (CP‐Ti) was investigated by asymmetric cyclic stress‐controlled experiments at room temperature. The effects of mean stress, ...stress amplitude, stress ratio, and peak stress on ratcheting behavior and fatigue life were discussed. It was found that increasing mean stress, stress amplitude, and peak stress or decreasing stress ratio reduced fatigue life and promoted ratcheting behavior. The applicability of different fatigue life models was analyzed, and a new stress ratio‐related failure model was proposed based on the exponential increase of fatigue life with stress ratio. Among all the models investigated in this study, the exponential stress ratio‐related model has more advantage in fatigue life predictions for CP‐Ti under ratcheting‐fatigue interaction.
Macroautophagy/autophagy is a multistep cellular process that sequesters cytoplasmic components for lysosomal degradation. BECN1/Beclin1 is a central protein that assembles cofactors for the ...formation of a BECN1-PIK3C3-PIK3R4 complex to trigger the autophagy protein cascade. Discovering the regulators of BECN1 is important for understanding the mechanism of autophagy induction. Here, we demonstrate that TRIM59, a tripartite motif protein, plays an important role in autophagy regulation in non-small cell lung cancer (NSCLC). On the one hand, TRIM59 regulates the transcription of BECN1 through negatively modulating the NFKB pathway. On the other hand, TRIM59 regulates TRAF6 induced K63-linked ubiquitination of BECN1, thus affecting the formation of the BECN1-PIK3C3 complex. We further demonstrate that TRIM59 can mediate K48-linked ubiquitination of TRAF6 and promote the proteasomal degradation of TRAF6. Taken together, our findings reveal novel dual roles for TRIM59 in autophagy regulation by affecting both the transcription and the ubiquitination of BECN1.
Abbreviations: ACTB: actin beta; BECN1: beclin 1; CHX: cycloheximide; CQ: chloroquine; GFP: green fluorescent protein; HA: haemagglutinin tag; His: polyhistidine tag; LC3B: microtubule associated protein 1 light chain 3 beta; NFKB: nuclear factor kappa B; NFKBIA: NFKB inhibitor alpha; NSCLC: non-small cell lung cancer; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; RELA: RELA proto-oncogene, NF-kB subunit; SQSTM1: sequestosome 1; tGFP: Turbo green fluorescent protein; TRAF6: TNF receptor associated factor 6; TRIM59: tripartite motif containing 59; B: ubiquitin
2D semiconducting transition metal dichalcogenides (TMDs) are emerging as promising candidates in the pursuit of advancing semiconductor technology. One major challenge for integrating 2D TMD ...materials into practical applications is developing an epitaxial technique with robust reproducibility for single‐oriented growth and thus single‐crystal growth. Here, the growth of single‐orientated MoS2 on c‐plane sapphire with atomically thin Fe2O3 decoration layers under various growth conditions is demonstrated. The statistical data highlight robust reproducibility, achieving a single orientation ratio of up to 99%. Density functional theory calculations suggest that MoS2 favors a 0° alignment (112¯0//112¯0$ {11\bar{2}0} //\ {11\bar{2}0} $) on the Fe2O3 (0001) surface. This preference ensures single‐oriented growth, even on mirror‐reflected exposed surfaces which typically lead to antiparallel domains. Subsequent optical and electrical analyses confirm the uniformity and undoped nature of MoS2 on Fe2O3‐decorated sapphire, showing its quality is comparable to MoS2 grown on bared sapphires. The results underscore the potential of Fe2O3‐decorated sapphire as an effective substrate for the consistent and high‐quality epitaxial growth of 2D TMDs, illuminating the pathway to epitaxial control of 2D TMD orientation through strategic modulation of crystalline atomic surfaces.
Transition metal dichalcogenides face challenges of applications in advancing semiconductors. This work demonstrates robust reproducibility in the growth of single‐oriented MoS2 on Fe2O3‐decorated sapphire, achieving a remarkable 99% ratio. Simulations reveal a preferred 0° alignment on the Fe2O3‐(0001) surface, ensuring single‐oriented growth even on mirror‐reflected surfaces. These findings highlight Fe2O3‐decorated sapphires as effective substrates, enabling epitaxial control of TMD orientation.
Integration of 2D materials on dielectric planar optical waveguides can make available new functionalities from the 2D materials' enhanced optoelectronic properties, such as nonlinearity, light ...emission, modulation, photodetection, and saturable absorption. However, the conventional integration schemes involving either the transfer of 2D materials onto prepatterned nonplanarized topology of photonic integrated circuits (PICs) or the growth and patterning of dielectric materials on 2D materials can degrade the properties of either the dielectric or the 2D material. Here, a fundamentally new and practical scheme is introduced for integrating 2D materials with PICs on a planar surface. The scheme can maintain large optical overlap with the 2D material by harnessing bound states in the continuum. This approach applies to integration of any 2D material on any single‐crystal dielectric substrate, and inherently offers strong light–matter interactions. Here, the approach is demonstrated with various hybrid photonic devices including thermo‐optic switches and filters, ultrafast photodetectors with 40‐GHz detection bandwidth, and ultrafast electro‐optic modulators with 5‐GHz modulation bandwidth. Therefore, the new platform will significantly expand the hybrid integration between 2D materials and single‐crystal dielectrics to achieve unexpected photonic functionalities.
A fundamentally new and practical scheme is introduced for integrating 2D materials with photonic integrated circuits on a planar surface. This approach applies to integration of any 2D material on any single‐crystal dielectric substrate, and offers strong light–matter interactions. Various hybrid photonic devices including thermo‐optic switches and filters, ultrafast photodetectors, and ultrafast electro‐optic modulators are demonstrated on this platform.
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