Formation of photonic band gaps by direct destructive interference.

We study a photonic band gap (PBG) material consisting of multiple waveguides. The multiconnected waveguides provide different paths for direct wave interference within the material. Using coaxial cables as waveguides, we are able to tune the PBG of the material. Using direct destructive interference between different paths of the waveguides, we experimentally observe a kind of PBG which is quite different from the traditional PBG that is caused by scattering in dielectrics with inhomogeneous refractive indices. Particularly, this newly observed PBG has an extremely strong wave attenuation, making electromagnetic (EM) waves in the PBG cannot even pass through one unit cell under certain conditions. We also systematically investigate the transmission of EM waves in our PBG materials and discuss the mechanism of band gap formation. Our results provide a new insight to develop new band gap materials for photons and phonons.

Singular multi-wavelength and multi-waveband transparencies generated by P T-symmetric dumbbell optical waveguide networks.

In this paper, we investigate the singular multi-wavelength and multi-waveband transparencies generated by P T-symmetric dumbbell optical waveguide networks composed of two materials, and obtain the number regularity for the transparency wavelengths of one-unit-cell system and the general relationships for the transmission and reflection coefficients of multi-unit-cell systems. Consequently, three types of exact transparencies produced by multi-unit-cell systems are found based on the aforementioned formulas: (i)exact multi-wavelength unidirectional or bidirectional transparency as the same as those of one-unit-cell system; (ii)exact multi-wavelength bidirectional transparency at which one-unit-cell system cannot produce exact transparency, generated by adjusting the number of unit cells; (iii)exact multi-wavelength bidirectional transparency at which one-unit-cell system produces exact transparency, also generated by adjusting the number of unit cells. It provides theoretical foundations for developing highly sensitive and multi-wavelength optical filters. On the other hand, we also discover that multi-unit-cell systems can create approximate multi-waveband bidirectional transparencies by adjusting the number of unit cells, which provides scientific support for developing high-performance optical stealth devices.

Highly efficient enhancement and extension of focusing ability for ring Pearcey beam by means of dual-region parabolic trajectory offset modulation.

It is a highly significant area of research to investigate how to effectively enhance the focusing ability of abruptly auto-focusing beams (AAFBs) while extending the focal length. We introduce a dual-region parabolic trajectory offset modulation to auto-focusing ring Pearcey beams (RPBs), presenting a novel, to the best of our knowlege, approach to extend the focal length while greatly enhancing their auto-focusing capabilities. Unlike directly introducing a linear chirp, which inevitably shortens the focal length to enhance the auto-focusing ability and allows only single focusing in the RPBs, our scheme can achieve a multi-focusing effect. Furthermore, we have experimentally generated such a beam, verifying our theoretical predictions. Our findings offer promising possibilities for generating optical bottles, trapping multiple particles periodically, and enhancing free-space optical communication capabilities.

Experimental generation of the polycyclic tornado circular swallowtail beam with self-healing and auto-focusing.

In this paper, the polycyclic tornado circular swallowtail beam (PTCSB) with autofocusing and self-healing properties is generated numerically and experimentally and their properties are investigated. Compared with the circular swallowtail beam (CSB), the optical distribution of the PTCSB presents a tornado pattern during the propagation. The number of spiral stripes, as well as the orientation of the rotation, can be adjusted by the number and the sign of the topological charge. The Poynting vectors and the orbital angular momentum are employed to investigate the physical mechanism of beam-rotating. In addition, we also introduce a sector-shaped opaque obstacle to investigate the self-healing property of the PTCSB, passing through it with different center angles and discuss the influence of the scaling factor along the propagation direction. Our results may expand the potential applications in the optical spanner and material processing.

Band-tunable achromatic metalens based on phase change material.

Achromatic metalens have the potential to significantly reduce the size and complexity of broadband imaging systems. A large variety of achromatic metalens has been proposed and most of them have the fixed achromatic band that cannot be actively modified. However, band-tunable is an important function in practical applications such as fluorescence microscopic imaging and optical detection. Here, we propose a bilayer metalens that can switch achromatic bands by taking the advantage of the high refractive index contrast of Sb2S3 between amorphous and crystalline state. By switching the state of Sb2S3, the achromatic band can be reversibly switched between the red region of visible spectrum (650-830 nm) and the near-infrared spectrum (830-1100 nm). This band-tunable design indicates a novel (to our knowledge) method to solve the problem of achromatic focusing in an ultrabroad band. The metalens have an average focusing efficiency of over 35% and 55% in two bands while maintaining diffraction-limited performance. Moreover, through proper design, we can combine different functionalities in two bands such as combining achromatic focusing and diffractive focusing. The proposed metalens have numerous potential applications in tunable displaying, detecting devices and multifunctional devices.

Dual-channel metasurfaces for independent and simultaneous display in near-field and far-field.

The operation of near-field and far-field can be employed to display holographic and nanoprinting images, which significantly improves the information density. Previous studies have proposed some approaches to display the images independently or simultaneously, but cannot satisfy these two characteristics in a single structure under the same incident light. Here, a single layer multifunctional metasurface is proposed to display a nanoprinting image and a holographic image independently and simultaneously. By tailoring the dimensions of each nanobricks and adopting different orientation angle, the amplitude and phase can be artificially designed. Moreover, enabled by the simulated annealing algorithm, we take the impact of both amplitude and phase of each nanobrick into consideration, which eliminates the unnecessary influence of amplitude on holographic image. Compared with previous work, our metasurfaces markedly improve the quality of holographic image with simple structures while not affecting the nanoprinting image. To be exact, it breaks the coupling between the near-field and far-field, achieving independent and simultaneous control of both fields. Our proposed metasurfaces carry characteristics of simple manufacture, little crosstalk, and great compactness, which provides novel applications for image displays, optical storage and information technology.

Communication wavelength investigation of bound states in the continuum of one-dimensional two-material periodic ring optical waveguide network.

In this study, a one-dimensional (1D) two-material period ring optical waveguide network (TMPROWN) was designed, and its optical properties were investigated. The key characteristics observed in the 1D TMPROWN include the following: (1) Bound states in continuum (BICs) can be generated in the optical waveguide network. (2) In contrast to the BICs previously reported in optical structures, the range of the BICs generated by the 1D TMPROWN is not only larger, but also continuous. This feature makes it possible for us to further study the electromagnetic wave characteristics in the range of the BICs. In addition, we analyzed the physical mechanisms of the BICs generated in the 1D TMPROWN. The 1D TMPROWN is simple in structure, demonstrates flexibility with respect to adjusting the frequency band of the BICs, and offers easy measurement of the amplitude and phase of electromagnetic waves. Hence, further research on high-power super luminescent diodes, optical switches, efficient photonic energy storage, and other optical devices based on the 1D TMPROWN designed in this study is likely to have implications in a broad range of applications.

Potent and Selective RIPK1 Inhibitors Targeting Dual-Pockets for the Treatment of Systemic Inflammatory Response Syndrome and Sepsis.

Sepsis, characterized with high risk of life-threatening organ dysfunction, represents a major cause of health loss and the World Health Organization (WHO) labelled sepsis as the most urgent unmet medical need in 2017. The emerging biological understanding of the role of RIPK1 in sepsis has opened up an exciting opportunity to explore potent and selective RIPK1 inhibitors as an effective therapeutic strategy for SIRS and sepsis therapy. Herein, we have synthesized a class of highly potent dual-mode RIPK1 inhibitors occupying both the allosteric and the ATP binding pockets, exemplified by compound 21 (ZB-R-55) which is about 10-fold more potent than GSK2982772, and exhibits excellent kinase selectivity, good oral pharmacokinetics and good therapeutic effects in the LPS-induced sepsis model, suggesting that compound ZB-R-55 is a highly promising preclinical candidate.

Ultrawide photonic band gaps with the limit of gap-midgap ratio of 200% produced from complete-connected networks.

A kind of one-dimensional (1D) complete-connected network (CCN) is designed and its extraordinary optical property for producing an ultrawide photonic band gap (PBG) is investigated. The gap-midgap ratio formulaes of the largest PBGs created by CCNs are analytically derived, and the results indicate that with the increment of the node number in a unit cell, the number of the loops that can produce antiresonances increases fleetly, and consequently the gap-midgap ratio of the PBG produced by CCNs enlarges rapidly and tends rapidly to the limit at 200%. Moreover, the general transmission formula for 1D CCNs is analytically determined. Due to the periodicity, two types of transmission resonance peaks are generated, and the condition is analytically obtained from the transmission formula. This kind of CCN may have wide applications to design superwide band optical filters, optical devices with large PBGs and strong photonic attenuations, and other related optical communication and optical increment processing devices.

Near-infrared thermally modulated varifocal metalens based on the phase change material Sb2S3.

Focus-tunable metalenses play an indispensable role in the development of integrated optical systems. In this paper, the phase change material Sb2S3 is used in a thermally modulated varifocal metalens based on PB-phase for the first time. Sb2S3 not only has a real part of refractive index shift between the amorphous and crystalline state but also has low losses in both amorphous and crystalline states in the near-infrared region. By switching Sb2S3 between the two states, a metalens doublet with a variable focal length is proposed. Moreover, the full width at half maximum of each focal point is close to the diffraction limit. And the focusing efficiency can be over 50% for the two focal points. Together with the advantage of precise thermal control, the proposed metalens has great potential in the application of multi-functional devices, biomedical science, communication and imaging.

Symmetric Pearcey Gaussian beams.

In this Letter, a new, to the best of our knowledge, type of autofocusing and symmetric beam arisen from two quartic spectral phases is introduced in theory and experiment. The symmetric Pearcey Gaussian beam (SPGB), formed with a Gaussian term and two multiplying Pearcey integrals, processes a focusing intensity approximately 1.32 times stronger than the intensity of the symmetric Airy beam. Its four off-axis main lobes split into four bending trajectories symmetrically after focusing. The rectangular intensity distribution and the focal length of the SPGB can be adjusted by two kinds of distribution factors. Additionally, the vortex-guiding property of the beam is demonstrated by embedding an off-axis vortex into the SPGB, which can be applied in particle guiding.

[Microbial community structure and transformation of indoles in soaking and fermentation of Indigo Naturalis].

The soaking and fermentation of Baphicacanthus cusia( Nees),the important intermediate link of Indigo Naturalis processing,facilitates the synthesis of indigo and indirubin precursors and the dissolution of endogenous enzymes and other effective components,while the role of microorganisms in the fermentation is ignored. The present study investigated the changes of microbial community structure in Indigo Naturalis processing based on 16 S amplicon sequencing and bioinformatics. Meanwhile,the contents of indigo,indirubin,isatin,tryptanthrin,indole glycoside,etc. were determined to explore the correlation between the microorganisms and the alterations of the main components. As demonstrated by the results,the microbial diversity decreased gradually with the fermentation,which bottomed out after the addition of lime. Proteobacteria,Bacteroidetes,and Firmicutes were the main dominant communities in the fermentation. The relative abundance of Proteobacteria declined gradually with the prolongation of fermentation time,and to the lowest level after the addition of lime. The relative abundance of Firmicutes increased,and that of Bacteroidetes decreased first and then increased. The contents of effective substances in Indigo Naturalis also showed different variation tendencies. As fermentation went on,indole glycoside decreased gradually; indigo first increased and then decreased; indirubin and isatin first decreased and then increased; tryptanthrin gradually increased. Those changes were presumedly related to the roles of microorganisms in the synthesis of different components. This study preliminarily clarified the important role of microorganisms in the soaking and fermentation and provided a scientific basis for the control of Indigo Naturalis processing and the preparation of high-quality Indigo Naturalis.

[Antipyretic activity and potential mechanism of Indigo Naturalis on 2,4-dinitrophenol-induced fever rat model].

As an effective antipyretic medicine,Indigo Naturalis has a long history of application in the field of Chinese medicine.The content of organics,mainly indigo and indirubin,is about 10%. However,the active ingredients and mechanism of its antipyretic effect have not yet been fully elucidated. In view of this,they were investigated in this study with the rectal temperature change as an indicator and 2,4-dinitrophenol-induced fever rats as subjects. The content of PGE2 and c AMP in the hypothalamus and the serum levels of TNF-α,IL-1ß and IL-6 were determined by ELISA. Moreover,the plasma samples of fever rats were analyzed by metabonomics in combination with UPLC-Q-TOF-MS for the exploration of potential biomarkers and the discussion on the antipyretic mechanism of Indigo Naturalis and its active ingredients. The results showed that the rising trend of rectal temperature in rats was suppressed 0. 5 h after the treatment with Indigo Naturalis,organic matter,indigo or indirubin as compared with the rats of model group( P < 0. 05),among which Indigo Naturalis and organic matter had better antipyretic effect. ELISA results showed that organic matter and indigo can inhibit the expression of PGE2 and c AMP( P<0. 01),while Indigo Naturalis and organic matter were effective in curbing the increase in TNF-α( P<0. 05). A total of 21 endogenous metabolites were identified from the plasma samples of the Indigo Naturalis,organic matter,indigo and indirubin groups,which were mainly involved in glycerophospholipid metabolism.

Goos-Hänchen and Imbert-Fedorov shifts of off-axis Airy vortex beams.

Based on the angular spectrum of high order off-axis Airy vortex beams (AiVBs), Goos-Hänchen (GH) shifts and Imbert-Fedorov (IF) shifts near the Brewster angle are numerically calculated. It is found that both GH and IF shifts increase with the increase of the vortex's topological charge of AiVBs. The influences of the vortex's positions on GH and IF shifts are studied for the case of the topological charge m = 1. The studies of the off-axis vortex show that the influences of the vortex's position on shifts are inversely proportional to the distance between the vortex's position and the origin point.

Propagation dynamics of autofocusing circle Pearcey Gaussian vortex beams in a harmonic potential.

We introduce the circle Pearcey Gaussian vortex (CPGV) beams in a harmonic potential for the first time and investigate their abruptly autofocusing properties by theoretical analysis and numerical simulations in this paper. By varying the spatial distribution factors, one can effectively control the propagating dynamics of the beams, including the position of the focus, the radius of the focal light spot and the intensity contrast. Meanwhile, the magnitude of topological charges and the position of the vortex can alter the focal pattern and the intensity contrast. Furthermore, the position of the focus can be flexibly controlled in a tiny range by adjusting the scaled parameter of the incident beam properly.

Abruptly autofocusing chirped ring Pearcey Gaussian vortex beams with caustics state in the nonlinear medium.

We simulate the propagation of the abruptly autofocusing chirped ring Pearcey Gaussian vortex (CRPGV) beams with caustics by modulating the phase of a circularly symmetric optical wavefront appropriately. The propagation characteristics of the CRPGV beams are explored in the Kerr medium. Different caustic surfaces of revolution which can be used as optical bottles are formed during the propagation. We also introduce the influence of the initial input power, the chirp factor and the stochastic type perturbations for the CRPGV beams during the propagation. Furthermore, the dynamics of the optical bottle and the breathers-like structures are explored in detail.

Propagation of the first order annular Bessel Gaussian beams in a uniaxial crystal along the optical axis governed by the Pockels effect.

We investigate the first order annular Bessel Gaussian beams propagating in a strontium barium niobate (SBN) crystal governed by the Pockels effect. The left-hand circularly polarized incident waves propagating along the optical axis in the crystal give rise to the right-hand circularly polarized vortex fields with a topological charge of 2. If an external dc field is applied along the optical axis of the SBN crystal, the anisotropy strength can be controlled rapidly, and the rotational invariance around the optical axis is still maintained. In this case, the normalized intensity in the focal region, the power exchange between left-hand and right-hand components, and the exchange between the spin and orbit contributions of the angular momentum flux can be manipulated. We also consider the case where the incident waves are linearly polarized along the x axis. The cylindrical symmetry of two Cartesian components is broken during propagation due to the anisotropy, and the intensity distribution as well as the polarization state of the beams can be regulated electrically.

Characteristics and mechanism of all-optical switching based on a one-dimensional two-connected periodic triangle optical waveguide network.

In this study, an all-optical switch is designed using a one-dimensional two-segment-connected periodic triangular optical waveguide network, and its switching characteristics and mechanism are investigated. The performance of the switch is numerically calculated by using the network equation and the generalized eigenfunction method and we find it relatively excellent. Its switching efficiency ratio reached 3.7202×1016, which is 5 orders of magnitude larger than the best reported result. The switching threshold control energy is approximately 1.8×10-20J, which is 1 order of magnitude larger than the best reported result. The switch size is approximately 0.0672µm2 and the integration degree is up to 14per/µm2, and it can be used for micrometer chip integration. The switching time is close to 209 fs, which is the same order of magnitude as the previously reported results. In addition, the all-optical switching designed in this study not only exhibits excellent switching performance and a novel working mechanism, but also provides a new technology for the design of pump-free all-optical switching devices.

One-step preparation of ibuprofen fast- and sustained-release formulation by electrospinning with improved efficacy and reduced side effect.

In this study, we developed a one-step method to prepare ibuprofen fast- and sustained-release complex preparation. It was based on a double jets electrospinning process. Ibuprofen, a poorly water-soluble drug, was electrospun into fibers with polyvinyl pyrrolidone and hydroxypropyl methyl cellulose by two jets, respectively. The complex preparation had an enough initial dose come from fast-release part and a maintenance dose come from sustained-release part. Through the study of X-ray diffraction, differential scanning colorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), it was confirmed that ibuprofen was highly dispersed in nanofibers (NFs) in amorphous state. Because one line of NFs was very thin and could only extend along two directions, it was difficult for ibuprofen to transform from amorphous to crystal in this kind of approximate one-dimensional structure. Additionally, it was confirmed by animal experiment that the complex preparation also had a benefit to reduce gastric irritation that usually caused by traditional oral ibuprofen preparation. Therefore, the method developed in this study was a convenient and good-quality approach for ibuprofen pain-alleviating preparation.

Singular properties generated by finite periodic PT-symmetric optical waveguide network.

In this work we investigate the extraordinary characteristics of one-dimensional (1D) finite periodic parity-time (PT) symmetric network. On the basis of the transfer matrix method, three simple expressions are analytically obtained for transmission, left reflection and right reflection coefficients. For this periodic structure, we provide new criteria for the PT-symmetry breaking transition in terms of the elements of the transfer matrix and the scattering matrix. These criteria indicate that the exceptional points are related only to the cell structure, but not to the cell number. Utilizing these criteria and expressions, the relationships between the transmittances (reflectances) and the cell number are considered in detail. Furthermore, the conditions for ultrastrong transmission are analytically derived. We also show how a PT-symmetric network can become unidirectionally and bidirectionally transparent at specific frequencies. The conditions and related properties of unidirectional and bidirectional transparencies are also examined. Finally, we find that the finite periodic PT-symmetric network with certain cell number can be viewed as a unidirectionally invisible structure at the exceptional points. Our work may pave the way for designing a diversefamily of optical structures and networks with new properties and functionalities.