Topologically protected interface mode in plasmonic waveguide arrays

Recent realization of nontrivial topological phases in photonic systems has provided unprecedented opportunities in steering light flow in novel manners. Based on the Su–Schriffer–Heeger (SSH) model, a topologically protected optical mode was successfully demonstrated in a plasmonic waveguide array with a kinked interface that exhibits a robust nonspreading feature. However, under the same excitation conditions, another antikinked structure seemingly cannot support such a topological interface mode, which appears to be inconsistent with the SSH model. Theoretical calculations are carried out based on the coupled‐mode theory, in which the mode properties, excitation conditions, and the robustness are studied in detail. It is revealed that under the exact eigenstate excitations, both kinked and antikinked structures do support such robust topological interface modes; however, for a realistic single‐waveguide input only the kinked structure does so. It is concluded that the symmetry of interface eigenmodes plays a crucial role, and the odd eigenmode in a kinked structure offers the capacity to excite the nonspreading interface mode in the realistic excitation of a one‐waveguide input. Our finding deepens the understanding of mode excitation and propagation in coupled waveguide systems, and could open a new avenue in optical simulations and photonic designs.

     

Broadband spin‐controlled focusing via logarithmic‐spiral nanoslits of varying width

This work presents analytical, numerical and experimental demonstrations of light diffracted through a logarithmic spiral (LS) nanoslit, which forms a type of switchable and focus‐tunable structure. Owing to a strong dependence on the incident photon spin, the proposed LS‐nanoslit converges incoming light of opposite handedness (to that of the LS‐nanoslit) into a confined subwavelength spot, while it shapes light with similar chirality into a donut‐like intensity profile. Benefitting from the varying width of the LS‐nanoslit, different incident wavelengths interfere constructively at different positions, i.e., the focal length shifts from 7.5 μm (at λ = 632.8 nm) to 10 μm (at λ = 488 nm), which opens up new opportunities for tuning and spatially separating broadband light at the micrometer scale.

     

Unveiling the correlation between non‐diffracting tractor beam and its singularity in Poynting vector

This paper investigates the singular optics of nonparaxial light beams in the near field when the light behaves as a tractor beam. New insights into the optical pulling force, which is usually represented by integrating the stress tensor at a black box enclosing the object, are interpreted by the optical singularity of the Poynting vector. The negative nonconservative pulling force originates from the transfer of the azimuthal Poynting vector to the longitudinal component partly owing to the presence of a scatterer. The separatrice pattern and singularity shifts of the Poynting vector unanimously exhibit a differentiable near‐field distribution in the presence of optical pulling force. A new method is established to calculate the near‐field optical force using the differential Poynting vector in the far field. The results obtained provide a clear physical interpretation of the light–matter interaction and manifest the significance of singular optics in manipulating objects.

     

Recent research advances of the biomimetic tumor microenvironment and regulatory factors on microfluidic devices: A systematic review

Tumor microenvironment is a multicomponent system consisting of tumor cells, noncancer cells, extracellular matrix, and signaling molecules, which hosts tumor cells with integrated biophysical and biochemical elements. Because of its critical involvement in tumor genesis, invasion, metastasis, and resistance, the tumor microenvironment is emerging as a hot topic of tumor biology and a prospective therapeutic target. Unfortunately, the complex of microenvironment modeling in vitro is technically challenging and does not effectively generalize the local tumor tissue milieu. Recently, significant advances in microfluidic technologies have provided us with an approach to imitate physiological systems that can be utilized to mimic the characterization of tumor responses with pathophysiological relevance in vitro. In this review, we highlight the recent progress and innovations in microfluidic technology that facilitates the tumor microenvironment study. We also discuss the progress and future perspective of microfluidic bionic approaches with high efficiency for the study of tumor microenvironment and the challenges encountered in cancer research, drug discovery, and personalized therapy.     

Secondary Metabolites of Clinacanthus nutans

Chemistry of Natural Compounds -     

A New Ketone Derivative from Victoria amazonica

Chemistry of Natural Compounds - A new ketone, vicamazone (4-(2-butoxyethoxy)-4-methylpentan-2-one) (1), was isolated from the leaves of Victoria amazonica (Nymphaeaceae). The structure of the new...     

Seco-Abietanoids from Cryptomeria japonica and Their Inhibitory Activity Toward Xanthine Oxidase

Chemistry of Natural Compounds - A new seco-abietanoid, 12-methoxy-7-oxo-6,7-secoabieta-8,11,13-trien-6-oic acid (1), and a known seco-abietanoid,12-hydroxy-6,7-secoabieta-8,11,13-triene-6,7-dial...     

A Novel Biphenyl Derivative from Cinnamomum insulari-montanum

Chemistry of Natural Compounds - A novel biphenyl derivative, insularione (3,3′,4,4′,6-pentahydroxy-3,4-dihydro-[1,1′-biphenyl]-2,5-dione) (1), was isolated from the stems of...     

Simulation of nuclide migration in a middle- and low-level radioactive waste repository based on GMS

Journal of Radioanalytical and Nuclear Chemistry - Groundwater is the most important factor contributing to the diffusion and migration of radionuclides in the repository. In this paper, the...     

石墨烯纤维材料的化学气相沉积生长方法

石墨烯纤维材料是以石墨烯为主要结构基元沿某一特定方向组装而成或由石墨烯包覆纤维状基元形成的宏观一维材料。根据组成基元的不同可将石墨烯纤维材料分为石墨烯纤维和石墨烯包覆复合纤维。石墨烯纤维材料在一维方向上充分发挥了石墨烯高强度、高导电、高导热等特点,在智能纤维与织物、柔性储能器件、便携式电子器件等领域具有广阔的应用前景。随着化学气相沉积(Chemical Vapor Deposition,CVD)制备石墨烯薄膜技术的发展,CVD技术也逐渐应用于石墨烯纤维材料的制备。利用CVD法制备石墨烯纤维可避免传统纺丝工艺中繁琐的氧化石墨烯(Graphene Oxide,GO)还原过程。同时,通过CVD法直接将石墨烯沉积至纤维表面可以保证石墨烯与纤维基底之间强的粘附作用,提高复合纤维的稳定性,同时可实现对石墨烯质量的有效调控。本文综述了石墨烯纤维材料的CVD制备方法,石墨烯纤维材料优异的力学、电学、光学性质及其在智能传感、光电器件、柔性电极等领域的应用,并展望了CVD法制备石墨烯纤维材料未来的发展方向。