548 research outputs found

    Graphene Acoustic Devices

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    In 2011, Ren’s group has developed the first graphene sound source device in the world. This is the first time that the graphene applications have been extended into acoustic area. The graphene sound source can produce sound in a wide sound frequency range from 100 Hz to 50 kHz. After that, we have innovated the first graphene earphone, which can be used both for human and animals. In 2017, both the sound detection and sound emission have been integrated into one graphene device, which is called graphene artificial throat. In this book chapter, more details for developing those graphene acoustic devices will be introduced, which can help to boost the real applications of graphene devices

    Periodic driving induced helical Floquet channels with ultracold atoms in momentum space

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    Employing the external degrees of freedom of atoms as synthetic dimensions renders easy and new accesses to quantum engineering and quantum simulation. As a recent development, ultracold atoms suffering from two-photon Bragg transitions can be diffracted into a series of discrete momentum states to form a momentum lattice. Here we provide a detailed analysis on such a system, and, as a concrete example, report the observation of robust helical Floquet channels, by introducing periodic driving sequences. The robustness of these channels against perturbations is confirmed, as a test for their topological origin captured by Floquet winding numbers. The periodic switching demonstrated here serves as a testbed for more complicated Floquet engieering schemes, and offers exciting opportunities to study novel topological physics in a many-body setting with tunable interactions.Comment: partial overlap with the last section of arxiv:1906.12016V1, which was left out of the published versio

    Adsorption of phenylacetylene on Si(100)-2×1: Reaction mechanism and formation of a styrene-like π-conjugation system

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    This is the published version. Copyright 2003 American Physical SocietyThe interactions of phentylacetylene and phenylacetylene−α−d1 with Si(100)−2×1 have been studied as a model system to mechanistically understand the adsorption of conjugated π-electron aromatic substitutions on Si(100)−2×1. Vibrational signatures show that phenylacetylene covalently binds to the surface through a [2+2]-like cycloaddition pathway between the external C≡C and Si=Si dimer, forming styrene-like conjugation structure which was further supported by the chemical-shift of C 1s core level. These experimental results are consistent with the density-functional theory [B3LYP/6−311//+G(d)] calculations. The resulting styrene-like conjugation structures may possibly be employed as an intermediate for further organic syntheses and fabrication of molecular architecture for modification and functionalization of Si surfaces, or as a monomer for polymerization on Si surfaces

    A novel approach for 25-gauge transconjunctival sutureless vitrectomy to evaluate vitreous substitutes in rabbits

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    AIM: To improve the standard three-port vitrectomy for establishing and evaluating an endotamponade model in rabbits. METHODS: Three ports were prepared near the third eyelid of rabbits, and the infusion port was placed at the inferior nasal quadrant with the inserted cannula linking with a self-designed handheld rigid infusion catheter. All right eyes of rabbits underwent a modified 25-gauge vitrectomy and were subsequently filled with balanced salt solution, silicone oil, and eight-arm polyethylene glycols (8-arm PEGs) hydrogel separately for comparison. Ophthalmic examinations were performed regularly to record the changes after the surgery. RESULTS: Successful vitrectomy was achieved among 44 chinchilla rabbits. The mean operation time was 4.51±1.25min. Four eyes (9.1%) presented limited lens touch and two eyes (4.5%) showed retinal touch during surgery. Incision leakage was found in three eyes (6.8%) after surgery. There was no endophthalmitis, hemorrhage, or retinal detachment during the observation period and ophthalmic examinations after the implantation of vitreous substitutes. CONCLUSION: The modified technique of the standard vitrectomy applied in the endotamponade model in rabbits shows excellent safety and practicality

    Rich Collection of n-Propylamine and Isopropylamine Conformers: Rotational Fingerprints and State-of-the-Art Quantum Chemical Investigation

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    The conformational isomerism of isopropylamine and n-propylamine has been investigated by means of an integrated strategy combining high-level quantum-chemical calculations and high-resolution rotational spectroscopy. The equilibrium structures (and thus equilibrium rotational constants) as well as relative energies of all conformers have been computed using the so-called "cheap" composite scheme, which combines the coupled-cluster methodology with second-order Møller-Plesset perturbation theory for extrapolation to the complete basis set. Methods rooted in the density functional theory have been instead employed for computing spectroscopic parameters and for accounting for vibrational effects. Guided by quantum-chemical predictions, the rotational spectra of isopropylamine and n-propylamine have been investigated between 2 and 400 GHz with Fourier transform microwave and frequency-modulation millimeter/submillimeter spectrometers. Spectral assignments confirmed the presence of several conformers with comparable stability and pointed out possible Coriolis resonance effects between some of them

    A Zinc Finger Motif in the P1 N Terminus, Highly Conserved in a Subset of Potyviruses, Is Associated with the Host Range and Fitness of Telosma Mosaic Virus

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    P1 is the first protein translated from the genomes of most viruses in the family Potyviridae, and it contains a C-terminal serine-protease domain that cis-cleaves the junction between P1 and HCPro in most cases. Intriguingly, P1 is the most divergent among all mature viral factors, and its roles during viral infection are still far from understood. In this study, we found that telosma mosaic virus (TelMV, genus Potyvirus) in passion fruit, unlike TelMV isolates present in other hosts, has two stretches at the P1 N terminus, named N1 and N2, with N1 harboring a Zn finger motif. Further analysis revealed that at least 14 different potyviruses, mostly belonging to the bean common mosaic virus subgroup, encode a domain equivalent to N1. Using the newly developed TelMV infectious cDNA clones from passion fruit, we demonstrated that N1, but not N2, is crucial for viral infection in both Nicotiana benthamiana and passion fruit. The regulatory effects of N1 domain on P1 cis cleavage, as well as the accumulation and RNA silencing suppression (RSS) activity of its cognate HCPro, were comprehensively investigated. We found that N1 deletion decreases HCPro abundance at the posttranslational level, likely by impairing P1 cis cleavage, thus reducing HCPro-mediated RSS activity. Remarkably, disruption of the Zn finger motif in N1 did not impair P1 cis cleavage and HCPro accumulation but severely debilitated TelMV fitness. Therefore, our results suggest that the Zn finger motif in P1s plays a critical role in viral infection that is independent of P1 protease activity and self-release, as well as HCPro accumulation and silencing suppression.This work is supported by grants from the Hainan Provincial National Science Foundation (grant nos. 2019RC010 and 322CXTD505), Sanya Yazhou Bay Sci-Tech City (SYND-2022-32 and SYND-2022-02), the National Natural Science Foundation of China (32060603), and the Central Public Interest Scientific Institution Basal Research Fund for Chinese Academy of Tropical Agricultural Sciences (19CXTD-33). We thank Fangfang Li (Chinese Academy of Agricultural Sciences) for providing pCHF3-35S-GFP and P19-expressing plasmidPeer reviewe
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