Gauge Field Induced Chiral Zero Mode in Five-Dimensional Yang Monopole Metamaterials.

Owing to the chirality of Weyl nodes characterized by the first Chern number, a Weyl system supports one-way chiral zero modes under a magnetic field, which underlies the celebrated chiral anomaly. As a generalization of Weyl nodes from three-dimensional to five-dimensional physical systems, Yang monopoles are topological singularities carrying nonzero second-order Chern numbers c_{2}=±1. Here, we couple a Yang monopole with an external gauge field using an inhomogeneous Yang monopole metamaterial and experimentally demonstrate the existence of a gapless chiral zero mode, where the judiciously designed metallic helical structures and the corresponding effective antisymmetric bianisotropic terms provide the means for controlling gauge fields in a synthetic five-dimensional space. This zeroth mode is found to originate from the coupling between the second Chern singularity and a generalized 4-form gauge field-the wedge product of the magnetic field with itself. This generalization reveals intrinsic connections between physical systems of different dimensions, while a higher-dimensional system exhibits much richer supersymmetric structures in Landau level degeneracy due to the internal degrees of freedom. Our study offers the possibility of controlling electromagnetic waves by leveraging the concept of higher-order and higher-dimensional topological phenomena.

Highly flexible organo-metal halide perovskite solar cells based on silver nanowire-polymer hybrid electrodes.

Flexible perovskite solar cells (FPSCs) have attracted considerable attention due to their broad application possibilities in next generation electronics. However, the commonly used transparent conductive electrodes (TCEs), such as indium tin oxide (ITO), suffer from poor flexible performance, impeding the development of FPSCs. Here, we propose a hybrid electrode (PUA/AgNWs/PH1000) comprising a thin percolation network of silver nanowires (AgNWs) inlaid on the surface of a flexible substrate (PUA) modified with a conductive layer (PH1000), which exhibits high optical transmittance and electrical conductivity, as well as robust mechanical flexibility. By applying the proposed PUA/AgNWs/PH1000 hybrid electrode in FPSCs, the resulting ITO-free devices exhibit the desired flexibility and mechanical stability; it can survive repeated continuous bending cycles and retain 77.4% of its initial power conversion efficiency after 10 000 bending cycles with the bending radius of 5 mm.

Mechanically and operationally stable flexible inverted perovskite solar cells with 20.32% efficiency by a simple oligomer cross-linking method.

Due to their great potential in wearable and portable electronics, flexible perovskite solar cells (FPSCs) have been extensively studied. The major challenges in the practical applications of FPSCs are efficiency, operational stability, and mechanical stability. Herein, we developed a facile approach by incorporating a cross-linking oligomer of trimethylolpropane ethoxylate triacrylate (TET) into perovskite films to simultaneously enhance the power conversion efficiency (PCE) and stability of FPSCs. A PCE of 20.32% was achieved, which are among the best results for the inverted FPSCs. Both mechanical and environmental stabilities were improved for the TET-incorporated FPSCs. In particular, the PCE retained approximately 87% of its initial value after 20,000 bending cycles at a radius of 4 mm. The inverted FPSCs retained 85% of the initial PCE after 500 h storage at 85 °C and 90% after 900 h continuous one-sun illumination. A joint experiment-theory analysis ascribed the underlying mechanism to the reduced defect densities, improved crystallinity, and stability of the perovskite absorbers on flexible substrates caused by TET incorporation.

Anomalous Electromagnetic Tunneling in Bianisotropic ϵ-µ-Zero Media.

Quantum tunneling, one of the most celebrated effects arising from the wave nature of matter, describes the partial penetration of an incident propagating wave through a potential barrier in the form of an evanescent field that exponentially decays from the incident interface. A similar tunneling effect has also been observed in classical systems, such as the frustrated total internal reflection. Here we reveal an unexplored form of tunneling for electromagnetic waves which features opposite behaviors for the electric and magnetic fields, with one turning into a growing field, and the other a decaying field, in a medium that exhibits both ϵ-µ-zero and bianisotropy. Our Letter provides a new mechanism for manipulating electromagnetic waves for novel device applications.

Efficient and stretchable organic light-emitting devices based on spontaneously formed disordered wrinkles.

We propose a facile, scalable strategy to introduce spontaneously formed disordered wrinkles into organic light-emitting devices (OLEDs) to enhance light extraction and realize stretchability of the devices. The luminance and current efficiency of the wrinkled OLEDs are improved by 37% and 18%, respectively, compared to the planar device. Meanwhile, broadband light scattering induced by the disordered wrinkles results in angle-stable electroluminescent spectra at wide viewing angles for the wrinkled OLEDs. The disordered wrinkles enable the OLEDs to be stretchable and withstand hundreds of stretching-releasing cycles at strain between 0% and 5%. This study provides a simple method to realize stretchable OLEDs with high efficiency.

Accuracy evaluation of combining gastroscopy, multi-slice spiral CT, Her-2, and tumor markers in gastric cancer staging diagnosis.

BACKGROUND: To evaluate the diagnostic accuracy of single gastroscopy, multi-slice spiral CT, HER-2 or tumor markers, and their combination in the diagnosis of gastric cancer. METHODS: A total of 98 patients with gastric cancer were selected as the research subjects. All patients underwent preoperative gastroscopy, MSCT, and the expression levels of HER-2, CEA, CA199, CA724, and CA242 were detected. A control group of 98 normal adults was selected to compare the risk factors for gastric cancer and to analyze the data. RESULTS: There was statistical significance in the expression of the 5 markers in tumor size (P < 0.05), but no statistical significance in other clinical data (P > 0.05). The tumor marker CEA in gastric mucosal tissue of patients with gastric cancer had the highest positive detection rate for gastric cancer, and the difference was statistically significant (P < 0.05) compared with gastroscopy, MSCT and other markers. The combined diagnosis had higher sensitivity, specificity and accuracy compared with the single diagnosis of gastric cancer staging, and the difference was statistically significant (P < 0.05). Compared with normal adults, patients with gastric cancer had statistically significant differences in diet, body mass index, and family genetic history (P < 0.05), while there was no statistically significant difference in whether they had type A blood (P > 0.05). CONCLUSION: The combined diagnosis of gastroscopy, MSCT, immunohistochemical marker Her-2, and tumor markers CEA, CA199, CA724, and CA242 can more accurately determine the clinical staging and lesion invasion depth of patients with gastric cancer and can significantly improve the sensitivity of diagnosis.

Linked Weyl surfaces and Weyl arcs in photonic metamaterials.

Generalization of the concept of band topology from lower-dimensional to higher-dimensional (n > 3) physical systems is expected to introduce new bulk and boundary topological effects. However, theoretically predicted topological singularities in five-dimensional systems-Weyl surfaces and Yang monopoles-have either not been demonstrated in realistic physical systems or are limited to purely synthetic dimensions. We constructed a system possessing Yang monopoles and Weyl surfaces based on metamaterials with engineered electromagnetic properties, leading to the observation of several intriguing bulk and surface phenomena, such as linking of Weyl surfaces and surface Weyl arcs, via selected three-dimensional subspaces. The demonstrated photonic Weyl surfaces and Weyl arcs leverage the concept of higher-dimension topology to control the propagation of electromagnetic waves in artificially engineered photonic media.

Recent progress in post treatment of silver nanowire electrodes for optoelectronic device applications.

Owing to the economical and practical solution synthesis and coating strategies, silver nanowires (AgNWs) have been considered as one of the most suitable alternative materials to replace commercial indium tin oxide (ITO) transparent electrodes. The primitive AgNW electrode cannot meet the requirements for preparing high performance optoelectronic devices due to its high contact resistance, large surface roughness and poor stability. Thus, various post-treatments for AgNW film optimization are needed before its actual applications, such as welding treatment to decrease contact resistance and passivation to increase film stability. This review investigates recent progress on the preparation and optimization of AgNWs. Moreover, some unique fabrication strategies to produce highly oriented AgNW films with unique anisotropic properties have also been carried out with detailed analysis. The representative devices based on the AgNW electrode have been summarized and discussed at the end of this review.

Momentum space toroidal moment in a photonic metamaterial.

Berry curvature, the counterpart of the magnetic field in the momentum space, plays a vital role in the transport of electrons in condensed matter physics. It also lays the foundation for the emerging field of topological physics. In the three-dimensional systems, much attention has been paid to Weyl points, which serve as sources and drains of Berry curvature. Here, we demonstrate a toroidal moment of Berry curvature with flux approaching to π in judiciously engineered metamaterials. The Berry curvature exhibits a vortex-like configuration without any source and drain in the momentum space. Experimentally, the presence of Berry curvature toroid is confirmed by the observation of conical-frustum shaped domain-wall states at the interfaces formed by two metamaterials with opposite toroidal moments.

Enhanced efficiency of organic light-emitting devices by using a directly imprinted nanopillared ultrathin metallic electrode.

An ultrathin metal film with high transmittance and conductivity has been demonstrated to be a promising transparent electrode for organic light-emitting devices (OLEDs). However, mediocre surface morphology and continuity of evaporated metal films and the surface plasmon-polaritons (SPPs) energy loss between the metal electrode and organic layer still limit the external quantum efficiency (EQE) of OLEDs. Here, nanoimprint lithography has been directly applied on the ultrathin Au film with underlying uncured photopolymer to fabricate the nanopillared anode. Both the conductivity and transmittance of the nanopillared ultrathin Au film have been improved due to the improvement of continuity and surface smoothness. As we expected, the SPPs mode has been coupled into photons and further extracted from OLEDs by using the nanopillared Au film anode. Finally, 19.2% and 70.1% enhancement of current efficiency were achieved compared to the planar device with ultrathin Au anode and ITO anode, respectively.

Improved light extraction in all-inorganic perovskite light-emitting devices with periodic nanostructures by nanoimprinting lithography.

We report an improved light extraction in all-inorganic perovskite light-emitting devices (PeLEDs) by integrating a periodic corrugated nanostructure at the metallic cathode/organic interface. Nanoimprinting lithography was used to introduce the nanostructures onto the surface of the electron transport layer directly to avoid influencing the morphology and crystallinity of the perovskite film underneath. The trapped energy at the metallic electrode has been successfully outcoupled by the excitation of the surface plasma polariton (SPP) modes induced by the periodic corrugations. The luminance and current efficiency of the periodically corrugated PeLED exhibit enhancements of 42% and 28%, respectively, compared to those of the planar PeLED. The finite-difference time-domain simulation was used to confirm the efficient outcoupling of the SPP modes.

Vortical Reflection and Spiraling Fermi Arcs with Weyl Metamaterials.

Scatterings and transport in Weyl semimetals have caught growing attention in condensed matter physics, with observables including chiral zero modes and the associated magnetoresistance and chiral magnetic effects. Measurement of electrical conductance is usually performed in these studies, which, however, cannot resolve the momentum of electrons, preventing direct observation of the phase singularities in scattering matrix associated with Weyl point. Here we experimentally demonstrate a helical phase distribution in the angle (momentum) resolved scattering matrix of electromagnetic waves in a photonic Weyl metamaterial. It further leads to spiraling Fermi arcs in an air gap sandwiched between a Weyl metamaterial and a metal plate. Benefiting from the alignment-free feature of angular vortical reflection, our findings establish a new platform in manipulating optical angular momenta with photonic Weyl systems.

Enhanced efficiency of all-inorganic perovskite light-emitting diodes by using F4-TCNQ-doped PTAA as a hole-transport layer.

We demonstrate an enhanced efficiency of all-inorganic perovskite light-emitting diodes (PeLEDs) by doping an electron acceptor of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) as a p-type dopant into the hole-transport layer (HTL) of poly-triarylamine (PTAA). The conductivity of the PTAA was improved by the formation of the CT complex through the electron transfer from the PTAA to F4TCNQ. Moreover, the hydrophobic surface of the PTAA leads to an improved surface morphology of the perovskite films compared to that on the conventionally used HTL of PEDOT:PSS. As a result, the maximum luminance and efficiency for the doped PTAA-based PeLEDs are 28020 cd/m2 and 13.5 cd/A, respectively, corresponding to 32.7% and 48% improvement in the efficiency compared to those of the pure PTAA or PEDOT:PSS-based PeLEDs.

Observation of chiral zero mode in inhomogeneous three-dimensional Weyl metamaterials.

Owing to the chirality of Weyl nodes, the Weyl systems can support one-way chiral zero modes under a strong magnetic field, which leads to nonconservation of chiral currents-the so-called chiral anomaly. Although promising for robust transport of optical information, the zero chiral bulk modes have not been observed in photonics. Here we design an inhomogeneous Weyl metamaterial in which a gauge field is generated for the Weyl nodes by engineering the individual unit cells. We experimentally confirm the presence of the gauge field and observe the zero-order chiral Landau level with one-way propagation. Without breaking the time-reversal symmetry, our system provides a route for designing an artificial magnetic field in three-dimensional photonic Weyl systems and may have potential for device applications in photonics.

Correlation between CT features of adrenocortical and adrenal medullary tumors and expression of miR-96 in serum.

Correlation between CT features of adrenocortical and adrenal medullary tumors and the expression of miR-96 in serum were investigated. A total of 230 patients with adrenocortical tumors and 194 patients with adrenal medullary tumors were selected in Dongying People's Hospital from August 2013 to August 2017. The two groups of patients underwent CT examination, and the signs and symptoms were recorded. The expression of miR-96 in the serum of the two groups was detected by RT-PCR, and the correlation between the expression of serum miR-96 and CT features was analyzed. In patients with adrenocortical tumor, serum miR-96 expression levels were significantly higher in patients with tumor diameter ≥5 cm than those with tumor diameter <5 cm (p<0.001). In patients with adrenal medullary tumor, serum miR-96 expression levels were significantly higher in patients with tumor diameter ≥3 cm than those with tumor diameter <3 cm (p<0.001). In patients with adrenocortical or adrenal medullary tumor, serum miR-96 expression levels were significantly higher in patients with peripheral infiltration than those without peripheral infiltration (p<0.001), and serum miR-96 expression levels were also significantly higher in patients with distant metastasis than those without distant metastasis (p<0.001). Serum levels of miR-96 in patients with benign adrenocortical and adrenal medullary tumors were significantly lower than those with malignant tumors in the same group (p<0.001). miR-96 may have oncogenic functions in patients with adrenocortical or adrenal medullary tumors. Increased expression level of miR-96 may promote proliferation, invasion and metastasis of tumors, and serum levels of miR-96 provide references for the diagnosis of adrenocortical and adrenal medullary tumors.

Surface plasmon-enhanced amplified spontaneous emission from organic single crystals by integrating graphene/copper nanoparticle hybrid nanostructures.

Organic single crystals have attracted great attention because of their advantages such as high carrier mobility and high thermal stability. Amplified spontaneous emission (ASE) is an important parameter for the optoelectronic applications of organic single crystals. Here, surface plasmon-enhanced ASE from the organic single crystals has been demonstrated by integrating graphene/copper nanoparticle (Cu NP) hybrid nanostructures. Graphene is fully accommodating to the topography of Cu NPs by the transfer-free as-grown method for the configuration of the hybrid nanostructures, which makes full electrical contact and strong interactions between graphene and the local electric field of surface plasmon resonances. The enhanced localized surface plasmon resonances induced by the hybrid nanostructures result in an enhanced intensity and lowered threshold of ASE from the organic single crystals. Moreover, the as-grown graphene sheets covering fully and uniformly on the Cu NPs act as a barrier against oxidation, and results in an enhanced stability of the fluorescence from the crystals.

As-grown graphene/copper nanoparticles hybrid nanostructures for enhanced intensity and stability of surface plasmon resonance.

The transfer-free fabrication of the high quality graphene on the metallic nanostructures, which is highly desirable for device applications, remains a challenge. Here, we develop the transfer-free method by direct chemical vapor deposition of the graphene layers on copper (Cu) nanoparticles (NPs) to realize the hybrid nanostructures. The graphene as-grown on the Cu NPs permits full electric contact and strong interactions, which results in a strong localization of the field at the graphene/copper interface. An enhanced intensity of the localized surface plasmon resonances (LSPRs) supported by the hybrid nanostructures can be obtained, which induces a much enhanced fluorescent intensity from the dye coated hybrid nanostructures. Moreover, the graphene sheets covering completely and uniformly on the Cu NPs act as a passivation layer to protect the underlying metal surface from air oxidation. As a result, the stability of the LSPRs for the hybrid nanostructures is much enhanced compared to that of the bare Cu NPs. The transfer-free hybrid nanostructures with enhanced intensity and stability of the LSPRs will enable their much broader applications in photonics and optoelectronics.

Efficient and mechanically robust stretchable organic light-emitting devices by a laser-programmable buckling process.

Stretchable organic light-emitting devices are becoming increasingly important in the fast-growing fields of wearable displays, biomedical devices and health-monitoring technology. Although highly stretchable devices have been demonstrated, their luminous efficiency and mechanical stability remain impractical for the purposes of real-life applications. This is due to significant challenges arising from the high strain-induced limitations on the structure design of the device, the materials used and the difficulty of controlling the stretch-release process. Here we have developed a laser-programmable buckling process to overcome these obstacles and realize a highly stretchable organic light-emitting diode with unprecedented efficiency and mechanical robustness. The strained device luminous efficiency -70 cd A(-1) under 70% strain - is the largest to date and the device can accommodate 100% strain while exhibiting only small fluctuations in performance over 15,000 stretch-release cycles. This work paves the way towards fully stretchable organic light-emitting diodes that can be used in wearable electronic devices.

Ultrathin and ultrasmooth Au films as transparent electrodes in ITO-free organic light-emitting devices.

An ultrathin, ultrasmooth and flexible Au film as an alternative of the indium-tin oxide (ITO) electrode in organic light-emitting devices (OLEDs) has been reported. The 7 nm Au film shows excellent surface morphology, optical and electronic characteristics including a root-mean-square roughness of 0.35 nm, a high transparency of 72% at 550 nm, and a sheet resistance of 23.75 Ω sq(-1). These features arise from the surface modification of the glass substrate by using a SU-8 film, which fixes metal atoms via chemical bond interactions between Au and SU-8 film to suppress the island growth mode. A 17% enhancement in current efficiency has been obtained from the OLEDs based on the ultrathin Au electrodes compared to that of the devices with the ITO electrodes. The OLEDs with the ultrathin Au/SU-8 anodes exhibit high flexibility and mechanical robustness.

Nitrogen-rich salts based on the energetic [monoaquabis(N,N-bis(1H-tetrazol-5-yl)amine)-zinc(II)] anion: a promising design in the development of new energetic materials.

Nitrogen-rich energetic salts involving various cations (lithium, 1; ammonium, 2; hydrazinium, 3; hydroxylammonium, 4; guanidinium, 5; aminoguanidinium, 6; diaminoguanidinium, 7; and triaminoguanidinium, 8) based on nitrogen-rich anion [Zn(BTA)2(H2O)](2-) (N% = 65.37, BTA = N,N-bis[1H-tetrazol-5-yl]amine anion) were synthesized with a simple method. The crystal structures of all compounds except 1, 2, and 6 were determined by single-crystal X-ray diffraction and fully characterized by elemental analysis and FT-IR spectroscopy. The thermal stabilities were investigated by differential scanning calorimetry (DSC). The DSC results show that all compounds exhibit high thermal stabilities (decomposition temperature >200 °C). Additionally, the heats of formation were calculated on the basis of the experimental constant-volume energies of combustion measured by using bomb calorimetry. Lastly, the sensitivities toward impact and friction were assessed according to Bundesamt für Materialforschung (BAM) standard methods.