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  1. Article ; Online: Sub-terahertz scanning near-field optical microscope using a quartz tuning fork based probe.

    Li, Xinxing / Sun, Jiandong / Jin, Lin / Shangguan, Yang / Chen, Kebei / Qin, Hua

    Optics express

    2023  Volume 31, Issue 12, Page(s) 19754–19765

    Abstract: We report a sub-terahertz scattering-type scanning near-field microscope (sub-THz s-SNOM) which uses a 6 mm long metallic tip driven by a quartz tuning fork as the near-field probe. Under continuous-wave illumination by a 94 GHz Gunn diode oscillator, ... ...

    Abstract We report a sub-terahertz scattering-type scanning near-field microscope (sub-THz s-SNOM) which uses a 6 mm long metallic tip driven by a quartz tuning fork as the near-field probe. Under continuous-wave illumination by a 94 GHz Gunn diode oscillator, terahertz near-field images are obtained by demodulating the scattered wave at both the fundamental and the second harmonic of the tuning fork oscillation frequency together with the atomic-force-microscope (AFM) image. The terahertz near-field image of a gold grating with a period of 2.3 µm obtained at the fundamental modulation frequency agrees well with the AFM image. The experimental relationship between the signal demodulated at the fundamental frequency and the tip-sample distance is well fitted with the coupled dipole model indicating that the scattered signal from the long probe is mainly contributed by the near-field interaction between the tip and the sample. This near-filed probe scheme using quartz tuning fork can adjust the tip length flexibly to match the wavelength over the entire terahertz frequency range and allows for operation in cryogenic environment.
    Language English
    Publishing date 2023-06-28
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1491859-6
    ISSN 1094-4087 ; 1094-4087
    ISSN (online) 1094-4087
    ISSN 1094-4087
    DOI 10.1364/OE.487167
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Construction of Medusa-Like Adhesive Carbon Nanotube Array Induced by Deformation of Alumina Sheets.

    Zhang, Kai / Chen, Kebei / Di, Jiangtao / Gong, Wenbin / Li, Zhuo / Zhang, Jin / Yao, Yagang

    Small (Weinheim an der Bergstrasse, Germany)

    2023  Volume 20, Issue 18, Page(s) e2306722

    Abstract: To change the binary structure of nanotube and nanotube array in vertically aligned carbon nanotube arrays, this work deposits regularly arranged amorphous alumina sheets on the classical array growth catalyst (10 nm-thick alumina and 2 nm-thick iron) ... ...

    Abstract To change the binary structure of nanotube and nanotube array in vertically aligned carbon nanotube arrays, this work deposits regularly arranged amorphous alumina sheets on the classical array growth catalyst (10 nm-thick alumina and 2 nm-thick iron) and obtains an array similar to the Medusa head. Subsequent experiments revealed that these alumina sheets show both unstable and stable qualities during growth: unstable in that they thermally deform and change their newly discovered characteristics of blocking carbon source diffusion, which regulates the nanotube growth order in specific areas; stable in that they withstand the deformation caused by heat and sequential growth of nanotubes, serving as a substrate and buffer layer for Medusa's hair, i.e., nanotube bundles on the array surface. Their combination splits this binary structure into a tertiary architecture consisting of nanotubes, nanotube bundles, and the array spanning nano-, micro-, and milli-meter. Benefiting from this structure, this array exhibits a unique near-isotropic adhesion characteristic compared to existing reports and outperforms classical and patterned arrays with the same classical catalyst and growth conditions.
    Language English
    Publishing date 2023-12-13
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2168935-0
    ISSN 1613-6829 ; 1613-6810
    ISSN (online) 1613-6829
    ISSN 1613-6810
    DOI 10.1002/smll.202306722
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Pharmacokinetic Analysis of Rosmarinic Acid and its Analog in Rat Plasma Using Liquid Chromatography-Tandem Mass Spectrometry.

    Jiang, Minjie / Fu, Shujie / Chen, Kebei / Li, Qing / Jiang, Weizhe

    Journal of chromatographic science

    2021  Volume 60, Issue 6, Page(s) 511–517

    Abstract: The anticancer effects of rosmarinic acid (RA) are a hotspot of current research. In order to enhance its pharmacological activity, N-substituted RA was prepared, and it has been shown to exhibit notable antitumor effects. In order to elucidate the ... ...

    Abstract The anticancer effects of rosmarinic acid (RA) are a hotspot of current research. In order to enhance its pharmacological activity, N-substituted RA was prepared, and it has been shown to exhibit notable antitumor effects. In order to elucidate the underlying mechanisms of action, pharmacokinetic analysis is necessary. In the present study, liquid chromatography-tandem mass spectrometric method, was used to determine the concentrations of RA and its analog, (E)-3-(3,4-dihydroxyphenyl)-2-(3-(3,4-dihydroxyphenyl)acrylamido)propanoic acid (A2) in plasma from rats. The analyses were divided into a C18 column (1.9 μm, 2.1 mm × 100 mm) with a security guard C18 column (5 μm, 2.1 mm × 10 mm) and a triple-quadrupole mass spectrometry with an electrospray ionization ion-source generates ions. The sample pretreatment is relevant to the one-step protein precipitation with isopropanol:ethyl acetate (v/v, 1:1) This method presented a linear association within ranges at the concentration of 5-2000 ng/mL for A2 and RA. Relative standard deviations in daily courses were <15% and the relative errors registered within 15%. The methods used in the present study make the unambiguous quantification and identification of RA and A2 possible in vivo. The present study is the first to focus on determining A2 and RA in rat plasma following oral administration. The results may provide a meaningful basis for the evaluation of the application of RA and its analog in clinical practice and also provide a reference method for the pharmacokinetic analysis of RA analogs.
    MeSH term(s) Animals ; Chromatography, High Pressure Liquid/methods ; Chromatography, Liquid/methods ; Cinnamates ; Depsides ; Rats ; Rats, Sprague-Dawley ; Reproducibility of Results ; Tandem Mass Spectrometry/methods ; Rosmarinic Acid
    Chemical Substances Cinnamates ; Depsides
    Language English
    Publishing date 2021-08-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 80141-0
    ISSN 1945-239X ; 0021-9665
    ISSN (online) 1945-239X
    ISSN 0021-9665
    DOI 10.1093/chromsci/bmab074
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Nanoscale phase separation on an AlGaN surface characterized by scanning diffusion microscopy.

    Liu, Boyang / Liu, Zhenghui / Xu, Gengzhao / Song, Wentao / Zhang, Chunyu / Chen, Kebei / Han, Sha / Sun, Xiaojuan / Li, Dabing / Xu, Ke

    Optics express

    2023  Volume 31, Issue 9, Page(s) 14945–14953

    Abstract: AlGaN is an important material for deep ultraviolet optoelectronic devices and electronic devices. The phase separation on the AlGaN surface means small-scale compositional fluctuations of Al, which is prone to degrade the performance of devices. In ... ...

    Abstract AlGaN is an important material for deep ultraviolet optoelectronic devices and electronic devices. The phase separation on the AlGaN surface means small-scale compositional fluctuations of Al, which is prone to degrade the performance of devices. In order to study the mechanism of the surface phase separation, the Al
    Language English
    Publishing date 2023-05-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1491859-6
    ISSN 1094-4087 ; 1094-4087
    ISSN (online) 1094-4087
    ISSN 1094-4087
    DOI 10.1364/OE.487405
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Numerical analysis of vibration modes of a qPlus sensor with a long tip.

    Chen, Kebei / Liu, Zhenghui / Xie, Yuchen / Zhang, Chunyu / Xu, Gengzhao / Song, Wentao / Xu, Ke

    Beilstein journal of nanotechnology

    2021  Volume 12, Page(s) 82–92

    Abstract: We study the oscillatory behavior of qPlus sensors with a long tilted tip by means of finite element simulations. The vibration modes of a qPlus sensor with a long tip are quite different from those of a cantilever with a short tip. Flexural vibration of ...

    Abstract We study the oscillatory behavior of qPlus sensors with a long tilted tip by means of finite element simulations. The vibration modes of a qPlus sensor with a long tip are quite different from those of a cantilever with a short tip. Flexural vibration of the tungsten tip will occur. The tip can no longer be considered as a rigid body that moves with the prong of the tuning fork. Instead, it oscillates both horizontally and vertically. The vibration characteristics of qPlus sensors with different tip sizes were studied. An optimized tip size was derived from obtained values of tip amplitude, ratio between vertical and lateral amplitude components, output current, and quality factor. For high spatial resolution the optimal diameter was found to be 0.1 mm.
    Language English
    Publishing date 2021-01-21
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2583584-1
    ISSN 2190-4286
    ISSN 2190-4286
    DOI 10.3762/bjnano.12.7
    Database MEDical Literature Analysis and Retrieval System OnLINE

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