Plasmonic high-harmonic generation (HHG) drew attention as a means of producing coherent extreme ultraviolet (EUV) radiation by taking advantage of field enhancement occurring in metallic ...nanostructures. Here a metal-sapphire nanostructure is devised to provide a solid tip as the HHG emitter, replacing commonly used gaseous atoms. The fabricated solid tip is made of monocrystalline sapphire surrounded by a gold thin-film layer, and intended to produce EUV harmonics by the inter- and intra-band oscillations of electrons driven by the incident laser. The metal-sapphire nanostructure enhances the incident laser field by means of surface plasmon polaritons, triggering HHG directly from moderate femtosecond pulses of ∼0.1 TW cm
intensities. The measured EUV spectra exhibit odd-order harmonics up to ∼60 nm wavelengths without the plasma atomic lines typically seen when using gaseous atoms as the HHG emitter. This experimental outcome confirms that the plasmonic HHG approach is a promising way to realize coherent EUV sources for nano-scale near-field applications in spectroscopy, microscopy, lithography and atto-second physics.
Although polycrystalline hexagonal boron nitride (PC-hBN) has been realized, defects and grain boundaries still cause charge scatterings and trap sites, impeding high-performance electronics. Here, ...we report a method of synthesizing wafer-scale single-crystalline hBN (SC-hBN) monolayer films by chemical vapor deposition. The limited solubility of boron (B) and nitrogen (N) atoms in liquid gold promotes high diffusion of adatoms on the surface of liquid at high temperature to provoke the circular hBN grains. These further evolve into closely packed unimodal grains by means of self-collimation of B and N edges inherited by electrostatic interaction between grains, eventually forming an SC-hBN film on a wafer scale. This SC-hBN film also allows for the synthesis of wafer-scale graphene/hBN heterostructure and single-crystalline tungsten disulfide.
Air-transmitted pathogens may cause severe epidemics showing huge threats to public health. Microbial inactivation in the air is essential, whereas the feasibility of existing air disinfection ...technologies meets challenges including only achieving physical separation but no inactivation, obvious pressure drops, and energy intensiveness. Here we report a rapid disinfection method toward air-transmitted bacteria and viruses using the nanowire-enhanced localized electric field to damage the outer structures of microbes. This air disinfection system is driven by a triboelectric nanogenerator that converts mechanical vibration to electricity effectively and achieves self-powered. Assisted by a rational design for the accelerated charging and trapping of microbes, this air disinfection system promotes microbial transport and achieves high performance: >99.99% microbial inactivation within 0.025 s in a fast airflow (2 m/s) while only causing low pressure drops (<24 Pa). This rapid, self-powered air disinfection method may fill the urgent need for air-transmitted microbial inactivation to protect public health.
High-harmonic generation by focusing a femtosecond laser onto a gas is a well-known method of producing coherent extreme-ultraviolet (EUV) light. This nonlinear conversion process requires high pulse ...intensities, greater than 1013 W cm-2, which are not directly attainable using only the output power of a femtosecond oscillator. Chirped-pulse amplification enables the pulse intensity to exceed this threshold by incorporating several regenerative and/or multi-pass amplifier cavities in tandem. Intracavity pulse amplification (designed not to reduce the pulse repetition rate) also requires a long cavity. Here we demonstrate a method of high-harmonic generation that requires no extra cavities. This is achieved by exploiting the local field enhancement induced by resonant plasmons within a metallic nanostructure consisting of bow-tie-shaped gold elements on a sapphire substrate. In our experiment, the output beam emitted from a modest femtosecond oscillator (100-kW peak power, 1.3-nJ pulse energy and 10-fs pulse duration) is directly focused onto the nanostructure with a pulse intensity of only 1011 W cm-2. The enhancement factor exceeds 20 dB, which is sufficient to produce EUV wavelengths down to 47 nm by injection with an argon gas jet. The method could form the basis for constructing laptop-sized EUV light sources for advanced lithography and high-resolution imaging applications.
Abstract Monodisperse spherical silica nanoparticles (SNPs) with diameters of 20–200 nm were employed to study size, dose, and cell-type dependent cytotoxicity in A549 and HepG2 epithelial cells and ...NIH/3T3 fibroblasts. These uniform SNPs of precisely controlled sizes eliminated uncertainties arising from mixed sizes, and uniquely allowed the probing of effects entirely size-dependent. Cell viability, membrane disruption, oxidative stress, and cellular uptake were studied. The extent and mechanism of SNP cytotoxicity were found to be not only size and dose dependent, but also highly cell type dependent. Furthermore, the 60 nm SNPs exhibited highly unusual behavior in comparison to particles of other sizes tested, implying interesting possibilities for controlling cellular activities using nanoparticles. Specifically, the 60 nm SNPs were preferentially endocytosed by cells and, at high doses, caused a disproportionate decrease in cell viability. The present work may help elucidate certain contradictions among existing results on nanoparticle-induced cytotoxicity. From the Clinical Editor Silica nanoparticles are being investigated in many research areas for their use in clinical applications. Nonetheless, the relationship between particle size and potential toxicity remains to be elucidated. In this article, the authors studied the biological effects of spherical SNPs with precise diameters between 20 and 200 nm on three different cell types and their results should provide more data on safety for better drug design.
Protection of endothelial integrity has been recognized as a frontline approach to alleviating sepsis progression, yet no effective agent for preserving endothelial integrity is available. Using an ...unusual anti-angiopoietin 2 (ANG2) antibody, ABTAA (ANG2-binding and TIE2-activating antibody), we show that activation of the endothelial receptor TIE2 protects the vasculature from septic damage and provides survival benefit in three sepsis mouse models. Upon binding to ANG2, ABTAA triggers clustering of ANG2, assembling an ABTAA/ANG2 complex that can subsequently bind and activate TIE2. Compared with a conventional ANG2-blocking antibody, ABTAA was highly effective in augmenting survival from sepsis by strengthening the endothelial glycocalyx, reducing cytokine storms, vascular leakage, and rarefaction, and mitigating organ damage. Together, our data advance the role of TIE2 activation in ameliorating sepsis progression and open a potential therapeutic avenue for sepsis to address the lack of sepsis-specific treatment.
Elizabethkingia infections are difficult to treat because of intrinsic antimicrobial resistance, and their incidence has recently increased. We conducted a propensity score-matched case-control study ...during January 2016-June 2017 in South Korea and retrospectively studied data from patients who were culture positive for Elizabethkingia species during January 2009-June 2017. Furthermore, we conducted epidemiologic studies of the hospital environment and mosquitoes. The incidence of Elizabethkingia increased significantly, by 432.1%, for 2016-2017 over incidence for 2009-2015. Mechanical ventilation was associated with the acquisition of Elizabethkingia species. Because Elizabethkingia infection has a high case-fatality rate and is difficult to eliminate, intensive prevention of contamination is needed.
Ultrashort extreme-ultraviolet pulses are a key tool in time-resolved spectroscopy for the investigation of electronic motion in atoms, molecules and solids. High-harmonic generation is a ...well-established process for producing ultrashort extreme-ultraviolet pulses by direct frequency upconversion of femtosecond near-infrared pulses. However, elaborate pump-probe experiments performed on the attosecond timescale require continuous efforts to improve the spatiotemporal coherence and also the repetition rate of the generated pulses. Here, we demonstrate a three-dimensional metallic waveguide for the plasmonic generation of ultrashort extreme-ultraviolet pulses by means of field enhancement using surface-plasmon polaritons. The intensity enhancement factor reaches a peak of ∼350, allowing generation up to the 43rd harmonic in xenon gas, with a modest incident intensity of ∼1 × 1011 W cm-2 . The pulse repetition rate is maintained as high as 75 MHz without external cavities. The plasmonic waveguide is fabricated on a cantilever microstructure and is therefore suitable for near-field spectroscopy with nanometre-scale lateral selectivity.
In this study, numerical simulation was employed to predict the performance and internal flow characteristics of the inlet of an axial-flow pump by assigning an absolute flow angle to the inlet guide ...vane (IGV) trailing-edge flow. Further, the finite volume method based on the three-dimensional Reynolds-averaged Navier-Stokes equations was employed to discretize the governing equations. The shear stress transport model was used as the turbulence model, and an appropriate number of nodes were selected for the hexahedral grid system through a grid-dependency test. The performance curve and changes in the internal flow field were investigated based on the variation in the flow angle at the inlet of the axial-flow pump. These results can be used to establish an efficient operational plan by adjusting the IGV angle of IGV when installing a variable IGV for an axial-flow pump.
Background
Major allergen sources Dermatophagoides farinae, Dermatophagoides pteronyssinus and Tyrophagus putrescentiae have been reported to have distinct microbiomes. The purpose of this study was ...to investigate the effect of each mite on airway epithelial cells as a model of airway allergic disease.
Methods
Transcriptomic analysis (RNA‐seq) of an airway epithelial cell line (BEAS‐2B) was performed to compare gene expression patterns after treatment with extracts of three mite species (D. farinae, D. pteronyssinus and T. putrescentiae). In addition, mycobiome deep sequencing of mites was employed to identify fungal species that interact with the microbiomes of the mites.
Results
Immune responses to bacteria were enriched only in the D. farinae‐treated group as this species harboured larger numbers of bacteria than the other mites, and the high level of LPS in D. farinae caused proinflammatory cytokine production in airway epithelial cells. In addition, antibiotic metabolism pathways were enriched in D. pteronyssinus‐treated cells but not in D. farinae ‐treated cells. Subsequent experiments revealed that D. pteronyssinus had a high fungal load that inhibited bacterial survival in this mite species.
Conclusion
The large amount of bacteria in D. farinae causes airway epithelial cells to produce more allergy‐related cytokines than D. pteronyssinus, since fungi present in D. pteronyssinus suppress the abundance of mite‐associated bacteria.
Comparative transcriptomic analysis of airway epithelial cells treated with extracts from Dermatophagoides farinae, D. pteronyssinus, and Tyrophagus putrescentiae reveal microbiome and mycobiome interaction in the mites and impact on allergic airway inflammation. D. farinae harbors a large amount of bacteria, which exerts a synergistic effect on allergic inflammation in vitro. D. pteronyssinus hosts a large amount of Aspergillus penicillioides, which suppresses bacterial microbiome growth in the mite.
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