Design and experimental realization of triple-band electromagnetically induced transparency terahertz metamaterials employing two big-bright modes for sensing applications.

Multi-band electromagnetically induced transparency (EIT) effects have attracted widespread attention due to their great application prospects. However, their realization is mainly based on the coupling of multiple sub-resonators that typically exceed the number of transparency peaks, resulting in complex structural designs and cumbersome preparation procedures. This paper reports a simple design of a terahertz metamaterial that can produce the triple-band EIT effect using two "big-bright" mode coupling of two sub-resonators. The design adopts the classical two-layer structure. A U-shaped split-ring resonator and a fork-shaped resonator form a periodic array on the surface of the flexible organic polymer material. Three transparency peaks around 0.59 THz, 1.07 THz, and 1.34 THz are experimentally realized, and their formation mechanisms are explored. Furthermore, the triple-band EIT metamaterial was prepared by the photolithography technology and characterized by terahertz time-domain spectroscopy. Theoretical simulation results agree well with experimental results. Sensing characteristics and slow light effects of the terahertz metamaterial are further discussed experimentally. The proposed triple-band EIT metamaterial having excellent properties, including thin size, good flexibility, simple and compact structure, and high sensing sensitivity, could provide guidance for the subsequent design and implementation of multifunctional multi-band EIT metamaterials.

Tunable dielectric metasurfaces by structuring the phase-change material.

Metasurfaces have made great progress in the last decade for generating miniature and integrated optical devices. The optical properties of metasurfaces can be tuned dynamically by integrating with phase-change materials. However, the efficiency of tunable metasurfaces remains a bit low, which is a disadvantage for the realistic applications of metasurfaces. Here, we demonstrate the tunable dielectric metasurfaces by structuring the phase-change material Ge2Sb2Te5. The unit cell of metasurface is composed of several Ge2Sb2Te5 nanopillars with different geometric parameters, and the incident light interacts with different nanopillars at diverse phases of Ge2Sb2Te5, leading to various functions. By elaborately arranging the Ge2Sb2Te5 nanopillars, various tunable optical devices have been realized, including tunable beam steering, reconfigurable metalens and switchable wave plate. The refractive direction, focal length and polarization state can be tuned through the phase transition of Ge2Sb2Te5. The phase-change metasurfaces based on Ge2Sb2Te5 nanostructures could be used in cameras, optical microscopy and adaptive optics.

Switchable transmissive and reflective metadevices based on the phase transition of vanadium dioxide.

Metasurfaces have made great progress in the past decade in generating various planar optical devices. However, most metasurfaces exhibit their functions in either reflection mode or transmission mode, with the other mode unutilized. In this work, we demonstrate switchable transmissive and reflective metadevices by combining metasurfaces with vanadium dioxide. The composite metasurface can work as a transmissive metadevice, with one function for vanadium dioxide in the insulating phase, and is changed to a reflective metadevice with another function for vanadium dioxide in the metallic phase. By carefully designing the structures, the metasurface can be switched from a transmissive metalens to a reflective vortex generator, or between a transmissive beam steering and a reflective quarter-wave plate through the phase transition of vanadium dioxide. The switchable transmissive and reflective metadevices have potential applications in imaging, communication, and information processing.

Tunable wave plates based on phase-change metasurfaces.

Wave plates based on metasurfaces have attracted intensive attention over the past decade owing to their compactness and design flexibility. Although various wave plates have been designed, their working wavelengths are fixed once they are made. Here we present a study on tunable wave plates based on phase-change metasurfaces made of Ge2Sb2Te5 nanopillar structures. The Ge2Sb2Te5 nanopillars can work as a high-efficiency transmissive half- or quarter-wave plate depending on their structural parameters. The working wavelength of wave plate can be tuned via the phase transition of Ge2Sb2Te5. Moreover, the polarization state of the transmitted light at a fixed wavelength can be modified by changing the crystallinity of Ge2Sb2Te5. The features suggest that tunable wave plates may have applications in optical modulators, molecular detection, and polarimetric imaging.

Effects of sodium tanshinone II A sulfonate on proliferation of fibroblasts in scar and the mRNA and protein expressions of transforming growth factor beta 1 and alpha smooth muscle actin / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the effects of sodium tanshinone II A sulfonate (STS) on proliferation of fibroblasts (Fbs) in human hypertrophic scar (HS), the mRNA and protein expressions of transforming growth factor beta 1 (TGF-β1) and alpha smooth muscle actin (α-SMA), and to investigate the scar inhibition mechanism of STS.</p><p><b>METHODS</b>Fbs were isolated from HS tissues that were removed from eight patients after burn injury, and they were cultured in vitro. Cells from the 3rd to the 6th passages were used in the experiment. Fbs were divided into control group and experimental group according to the random number table, and cells in the experimental group was divided into 0.050, 0.075, 0.100, 0.125, 0.150, 0.200 mg/mL STS subgroups. Cells in each subgroup were cultured with the corresponding concentration of STS, and cells in control group were cultured in equal volume of serum-free medium. After being cultured for 24 and 48 h, cell morphology was observed with inverted phase contrast microscope; cell proliferation was determined with MTT method and the proliferation inhibition rate (IR) was calculated. After being cultured for 48 h, the protein levels of TGF-β1 and α-SMA were determined with Western blotting; the mRNA expressions of TGF-β1 and α-SMA were determined with RT-PCR (no 0.200 mg/mL STS subgroup was set for these two indicators). Data were processed with factorial analysis of variance; differences between groups were processed with LSD test or Games-Howell test for unequal variances.</p><p><b>RESULTS</b>(1) Fbs grew well in control group, but reduction in adherence and disorderly arranged Fbs were observed in experimental group. The cells in experimental group became smaller and round, with increasing intracellular particles and necrosis. A large amount of necrotic debris of cells was observed in 0.200 mg/mL STS subgroup. (2) The absorbance value of Fbs in each experimental subgroup was significantly lower than that in control group (with P values all below 0.01). Along with the increase in the concentration of STS and extension of culture time, the IR value increased, showing a certain degree of time-concentration dependence. After being cultured with STS for 24 and 48 h, IR values of cells in the experimental subgroups were respectively 23.58%, 32.11%, 37.56%, 57.98%, 79.53%, 96.69% and 34.72%, 38.48%, 47.62%, 64.40%, 89.70%, 98.01%. (3) Except for the 0.050 mg/mL STS subgroup, the protein levels of TGF-β1 and α-SMA in the other subgroups were significantly lower than those in control group (with F values respectively 57.674, 47.795, P values all below 0.001). The protein levels of TGF-β1 and α-SMA reached the nadir in 0.150 mg/mL STS subgroup, respectively 0.34 ± 0.06, 0.33 ± 0.07. The relative expression amounts of TGF-β1 and α-SMA mRNA in the experimental subgroups were obviously decreased compared with those in control group (with F values respectively 68.548, 47.522, P values all below 0.001), which was most significant in 0.150 mg/mL STS subgroup, with TGF-β1 mRNA and α-SMA mRNA respectively 0.39 ± 0.07 and 0.42 ± 0.08.</p><p><b>CONCLUSIONS</b>STS can inhibit the proliferation of Fbs, reduce the protein and mRNA expressions of TGF-β1 and α-SMA, which may be beneficial to ameliorate the formation and contracture of HS, and it is assumed as a potential drug for treating scars.</p>

Effects of trichlorfon exposure on serum paraoxonase activity of pregnant mice and development of embryos / 上海第二医科大学学报

Objective To investigate the effects of maternal long-term exposure to low-dose trichlorfon on the serum paraoxonase (PON) activity of pregnant mice and development of embryos. Methods Female ICR mice (n=120) were randomly divided into control group and trichlorfon groups of different doses,and were managed by intragastric injection with trichlorfon of 0,2,10 and 50mg/kg,respectively. All the mice were managed once a day for a consecutive of 27 days,and were subjected to mating. The pregnant mice were continued to be managed with trichlorfon for 3 days,and were sacrificed on day 3 of gestation. The serum PON and acetylcholinesterase (AchE) activities were detected,and the development of embryos was evaluated. Results The serum PON activity of 2,10 and 50mg/kg trichlorfon group were (14.15?1.22),(12.78?1.80) and (10.45?1.95)IU/mL,respectively,and that of 50mg/kg trichlorfon group was significantly lower than that of control group [(13.37?2.31)IU/mL] (P0.05),while the the percentage of abnormal embryos of 50mg/kg trichlorfon group had an increased tendency. Conclusion Long-term exposure to low-dose trichlorfon can inhibit serum PON and AchE activity in pregnant mice without obvious effect on the development of embryos.