Covalent organic frameworks (COFs) with stable long-range ordered arrangements are promising materials for organic optoelectronics. However, their electrochemiluminescence (ECL) from non-ECL active ...monomers has not been realized. Here, we report a design strategy for ECL-emitting COF family. The donors and acceptors co-crystallized and stacked into the highly aligned array of olefin-linked COFs, so that electrons can be transported freely. By this means, a tunable ECL is activated from non-ECL molecules with the maximum efficiency of 32.1% in water with the dissolved oxygen as an inner coreactant, and no additional noxious co-reactant is needed any more. Quantum chemistry calculations further demonstrate that this design reduces the COFs’ band gaps and the overlap of electrons and holes in the excited state for better photoelectric properties and stronger ECL signals. This work exploits a basis to envisage the broad application potential of ECL–COFs for various biosensors and light-emitting display.
Filters play an invaluable role in most detection and communication systems, blocking unwanted, harmonic or mirrored waves. In this paper, two <inline-formula> <tex-math notation="LaTeX">3^{\mathrm ...{rd}} </tex-math></inline-formula>-order quasi-elliptical waveguide bandpass filters working at 400 GHz are developed based on TE 102 -mode oversized resonators. Transmission zeros are generated through the physical cross-couplings and the mixed modal bypass couplings. <inline-formula> <tex-math notation="LaTeX">H </tex-math></inline-formula>-plane off-axis coupling structures without any fragile irises are adopted to strengthen robustness and simplify manufacturing at such high terahertz frequencies. Effects of processing uncertainties on filters performance are discussed in detail to display error sensitivity. Two computer numerical control (CNC) machined filters exhibit a minimum insertion loss of about 1.5 dB in a 3 dB fractional bandwidth (FBW) with 12% centered at 390 GHz @ Filter-I, and 9% FBW with a center frequency of 394 GHz @ Filter-II, which are all mainly agreement with simulations. The performance is highlighted with the reported terahertz filters, which indicates that both architectural designs are still suited for the delicate CNC-milling restriction in such high WR-2.2 band.
The application of covalent organic frameworks (COFs) in electrochemiluminescence (ECL) is promising in environmental monitoring. Developing an emerging design strategy to expand the class of ...COF-based ECL luminophores is highly desirable. Here, a COF-based host–guest system was constructed through guest molecular assembly to deal with nuclear contamination analysis. The efficient charge transport network was formed by inserting an electron-withdrawing guest tetracyanoquinodimethane (TCNQ) into the open space of the COF host (TP-TBDA; TP = 2,4,6-trihydroxy-1,3,5-benzenetricarbaldehyde and TBDA = 2,5-di(thiophen-2-yl)benzene-1,4-diamine) with an electron-donating property; the construction of the COF-based host–guest system (TP-TBDA@TCNQ) triggered the ECL emission of non-emitting TP-TBDA. Furthermore, the dense active sites in TP-TBDA were utilized to capture the target substance UO2 2+. The presence of UO2 2+ broke the charge-transfer effect in TP-TBDA@TCNQ, resulting in the weakening of the ECL signal, thus the established ECL system integrating the low detection limit with high selectivity monitors UO2 2+. This COF-based host–guest system provides a novel material platform for constructing late-model ECL luminophores and creates an opportunity for the vigorous ECL technology.
Vitamin B6 is an essential water-soluble vitamin for humans. It is often used to prevent a variety of neuropathies, relieve vomiting, and relieve symptoms such as hand and foot neuritis. To evaluate ...whether vitamin B6 can alleviate the adverse reactions caused by the quadruple anti-Helicobacter pylori treatment regimen containing minocycline and metronidazole. In this randomized controlled trial, 280 patients with H. pylori infection were randomly placed into one of two treatment groups--the conventional treatment group and the vitamin B6 supplement treatment group--for 2 weeks. The primary endpoint was the total incidence of adverse reactions up to 2 weeks after treatment initiation. The study was designed according to CONSORT Medicinal Interventions. And it was registered with Chinese Clinical Trial Registry under the number ChiCTR2100053833. In terms of efficacy, vitamin B6 does not affect the efficacy of conventional regimen. In the vitamin B6 supplement treatment group, the incidence of adverse reactions was 56.92%, which was significantly lower than the 74.62% observed in the conventional treatment group. In addition, the severity of adverse reactions was also significantly reduced. The proportion of moderate to severe central nervous system symptoms decreased from 58.7 to 14.63%. And, the proportion of moderate to severe gastrointestinal reactions decreased from 33.33 to 0%. We speculate that the mechanism of vitamin B6 of reducing adverse reaction may be related to the production of GABA in the brain. Vitamin B6 can alleviate adverse reactions of the quadruple anti-H. pylori regimen containing minocycline and metronidazole.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
45.
Danshen: a phytochemical and pharmacological overview MEIm, Xiao-Dan; CAO, Yan-Feng; CHE, Yan-Yun ...
Chinese journal of natural medicines,
January 2019, 2019-Jan, 2019-01-00, 20190101, Letnik:
17, Številka:
1
Journal Article
Danshen, the dried root or rhizome of Salvia miltiorrhiza Bge., is a traditional and folk medicine in Asian countries, especially in China and Japan. In this review, we summarized the recent ...researches of Danshen in traditional uses and preparations, chemical constituents, pharmacological activities and side effects. A total of 201 compounds from Danshen have been reported, including lipophilic diterpenoids, water-soluble phenolic acids, and other constituents, which have showed various pharmacological activities, such as anti-inflammation, anti-oxidation, anti-tumor, anti-atherogenesis, and anti-diabetes. This article intends to provide novel insight information for further development of Danshen, which could be of great value to its improvement of utilization.
Molecular chemistry offers a unique toolkit to draw inspiration for the design of artificial metamolecules. For a long time, optical circular dichroism has been exclusively the terrain of natural ...chiral molecules, which exhibit optical activity mainly in the UV spectral range, thus greatly hindering their significance for a broad range of applications. Here we demonstrate that circular dichroism can be generated with artificial plasmonic chiral nanostructures composed of the minimum number of spherical gold nanoparticles required for three-dimensional (3D) chirality. We utilize a rigid addressable DNA origami template to precisely organize four nominally identical gold nanoparticles into a three-dimensional asymmetric tetramer. Because of the chiral structural symmetry and the strong plasmonic resonant coupling between the gold nanoparticles, the 3D plasmonic assemblies undergo different interactions with left and right circularly polarized light, leading to pronounced circular dichroism. Our experimental results agree well with theoretical predictions. The simplicity of our structure geometry and, most importantly, the concept of resorting on biology to produce artificial photonic functionalities open a new pathway to designing smart artificial plasmonic nanostructures for large-scale production of optically active metamaterials.
Platelets corrugated horn is a promising technology for its scalability to a large corrugated horn array. In this communication, we present the design, fabrication, measurement, and uncertainty ...analysis of a wideband 170-320 GHz platelet corrugated horn that features with low sidelobe across the band (<−30 dB). We also propose an accurate and universal method to analyze the axial misalignment of the platelets for the first time. It is based on the mode matching (MM) method with a closed-form solution to off-axis circular waveguide discontinuities obtained by using Graf addition theorem for the Bessel functions. The uncertainties introduced in the fabrication have been quantitatively analyzed using the Monte Carlo method. The analysis shows that the cross-polarization of the corrugated horn degrades significantly with the axial misalignment. It well explains the discrepancy between the designed and the measured cross-polarization of platelets corrugated horn fabricated in the THz band. The method can be used to determine the fabrication tolerance needed for other THz corrugated horns and evaluate the impact of the corrugated horn for astronomical observations.
With the evergrowing demand for miniaturization of photonic devices, the integration of different functionalities in a single module is highly desired for the next generation of ultracompact photonic ...devices. Optical modules based on the near field and scattered far field are both key elements in the construction of nanophotonic devices. However, integrating the near‐ and far‐field functionalities into a single module is a great challenge, which hinders the integration and minimization of optical devices. Here, a bifunctional integrated near‐ and far‐field optical launcher with a single metasurface structure is theoretically proposed and experimentally demonstrated, where the unidirectional launching of surface plasmon polaritons (SPPs) and the focusing of scattered far fields can be simultaneously achieved. Moreover, the SPP propagating direction and the real/virtual focus of the far‐field scattering can be actively controlled by the spin state of the incident light. With the additional degree of freedom provided by the positions of the metasurface elements, the optical performances of this bifunctional structure can be compared to the one with single functionality. The work provides a new platform for the integration and control of different optical components at subwavelength scale, and opens a way to design multifunctional optical devices for the future.
A single metasurface that can act as a bifunctional optical modulator with its geometric phase tailored in both near and far field is designed and demonstrated. It enables unidirectional launching of surface plasmon polaritons and focusing of far‐field light simultaneously. The near‐field propagation direction and the far‐field focusing polarity can be further actively controlled by the spin of incident light.
A W-band H-plane horn array antenna with tilted radiation beam based on waveguide structure is proposed in this paper. The designed antenna array consists of four H-plane antenna elements and a ...broadband feed network. The distribution of excitations is determined by the theory of maximum power transmission efficiency (MMPTE). A multiple branch coupler, two T-junctions and three fixed phase shifters are employed to construct the feed network, which can generate the required amplitude and phase in broadband frequency range from 80 GHz to 100 GHz. The computer numerical control (CNC) milling machines technology is employed to machine the feed network and antenna. All measured and simulated results are in good agreement, which verify the feasibility of the theory of MMPTE to generate a radiation beam directed to any angle from -35° to 35° with suitable excitation provided by the proposed feed network in this paper.
The structural isomerism of the covalent organic framework (COF) has a significant effect on the electrochemiluminescence (ECL) performance. Herein, we report a pair of isomeric COFs, ...(TFPB-BD(OMe)2-H and TAPB-BD(OMe)2-H), based on the different directions of imine linkages and further conversion of the imine to the quinoline structure. The obtained two isomeric COFs with the same composition and similar structures exhibit dramatic differences in the photoelectrochemical and ECL fields. Indeed, TFPB-BD(OMe)2-H demonstrates robust ECL emission superior to that of TAPB-BD(OMe)2-H. The difference in ECL performance is due to the stronger polar interaction of TFPB-BD(OMe)2-H than that of TAPB-BD(OMe)2-H. The polarity is derived from the uneven charge distribution within the framework and enhances the electron interactions. In addition, the ordered conjugate skeleton provides high-speed charge transport channels for carrier transport. Therefore, the TFPB-BD(OMe)2-H presents a smaller band gap energy and stronger polarization interaction, which are more favorable to charge migration to achieve stronger ECL signals. Furthermore, we describe a convenient ECL sensor for detecting toxic As(V) with an outstanding detection property and ultralow detection limit. This work provides a guiding principle for the design and development of ECL organic luminophores.
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