Search

The Sb2WO6 photocatalyst is synthesized by introducing oxygen vacancies through acetylene annealing. The number of oxygen vacancies can be adjusted by varying the annealing duration. Oxygen vacancy defects in Sb2WO6 change the surface chemical properties, enhance the separation of carriers, broaden the absorption of visible light, and activate the catalytic sites, resulting in overall enhancement of the photocatalytic properties. The significance of surface oxygen vacancies and pertinent mechanisms of photocatalytic oxidation are described. Our results reveal a promising method to improve the properties of Sb2WO6-based materials for applications such as the treatment of wastewater.

We theoretically investigate Goos-Hänchen effect for electron in single-layered semiconductor microstructure (SLSM) modulated by Rashba spin–orbit coupling (SOC). Due to the SOC effect, GH displacement is obviously dependent on spins, which allows electron spins to be separated in space dimension and results in spin polarization of electrons in semiconductors. Spin polarization ratio is associated with incident energy, incident direction and in-plane wave vector, e.g., it reaches maximum at resonance, but no spin polarization effect appears at normal incidence. In particular, both magnitude and sign of spin polarization ratio are controlled by external electric field or semiconductor-layer thickness, therefore, a manipulable spatial electron-spin splitter is obtained for semiconductor spintronics device applications.

Considering both Zeeman effect and spin–orbit coupling, we calculate dwell time for electron in single ferromagnetic-stripe device (SFSD), which can be constructed by patterning a nanosized ferromagnetic stripe on the surface of GaAs/AlxGa1-xAs heterostructure. Due to an intrinsic symmetry in the SFSD, dwell time is independent of electron spins, if only Zeeman effect is involved. However, the intrinsic symmetry is broken by spin–orbit coupling, which gives rise to spin-dependent dwell time for electron in the SFSD. As a result, electron spins can be separated in time dimension, which induces an obvious electron-spin polarization effect in the SFSD. Spin polarization ratio can be efficaciously modified by interfacial confining electric-field or strain engineering, which attributes to the dependence of effective potential felt by electron in the SFSD on spin–orbit couplings. Thus, the SFSD can act as a controllable temporal electron-spin splitter, a class of electron-spin polarized sources in semiconductor spintronics.

Abstract Non-orthogonal eigenstates are a fundamental feature of non-Hermitian systems and are accompanied by the emergence of nontrivial features. However, the platforms to explore non-Hermitian mode couplings mainly measure near-field effects, and the far-field behaviours remain mostly unexplored. Here, we study how a microcavity with non-Hermitian mode coupling exhibits eigenstate non-orthogonality by investigating the spatial field and the far-field polarization of cavity modes. The non-Hermiticity arises from asymmetric backscattering, which is controlled by integrating two scatterers of different size and location into a microdisk. We observe that the spatial field overlap of two modes increases abruptly to its maximum value, whilst different far-field elliptical polarizations of two modes coalesce when approaching an exceptional point. We demonstrate such features experimentally by measuring the far-field polarization from the fabricated microdisks. Our work reveals the non-orthogonality in the far-field degree of freedom, and the integrability of the microdisks paves a way to integrate more non-Hermitian optical properties into nanophotonic systems.

Abstract Single photon emission of quantum emitters (QEs) carrying internal degrees of freedom such as spin and angular momentum plays an important role in quantum optics. Recently, QEs in two-dimensional semiconductors have attracted great interest as promising quantum light sources. However, whether those QEs are characterized by the same valley physics as delocalized valley excitons is still under debate. Moreover, the potential applications of such QEs still need to be explored. Here we show experimental evidence of valley symmetry breaking for neutral QEs in WSe2 monolayer by interacting with chiral plasmonic nanocavities. The anomalous magneto-optical behaviour of the coupled QEs suggests that the polarization state of emitted photon is modulated by the chiral nanocavity instead of the valley-dependent optical selection rules. Calculations of cavity quantum electrodynamics further show the absence of intrinsic valley polarization. The cavity-dependent circularly polarized single-photon output also offers a strategy for future applications in chiral quantum optics.

Zinc oxide (ZnO) is an attractive material for gas sensors, and various ZnO-based sensors have been developed to detect gas pollution. In this work, a series of SiC/ZnO composites were fabricated by incorporating silicon carbide nanocrystals (SiC NCs) into ZnO microspheres by a grinding method. The SiC/ZnO composite exhibited a significantly enhanced gas sensitivity response toward NO gas in comparison to ZnO. The test revealed that the response of the composite was 251.1 for 100 ppm of nitrogen monoxide (NO), and the detection limit was as low as 100 ppb. Through spectral and comparative analyses, it has been indicated that the active functional groups of the SiC NCs have a substantial impact on the detection of NO, and the corresponding mechanism is studied and discussed. This work offers a simple strategy for the fabrication of SiC/ZnO material with enhanced sensitivity in sensing applications.

We investigate local high chirality inside a microcavity near exceptional points (EPs) achieved via asymmetric backscattering by two internal weak scatterers. At EPs, coalescent eigenmodes exhibit position-dependent and symmetric high chirality characteristics for a large azimuthal angle between the two scatterers. However, asymmetric mode field features appear near EPs, where two azimuthal regions in the microcavity classified by the scatterers exhibit different wave types and chirality. Such local mode field features are attributed to the symmetries of backscattering in direction and spatial distribution. The connections between the wave types, the symmetry of mode field distribution and different symmetries of backscattering near EPs are also discussed. Benefiting from the small size of weak scatterers, such microcavities with a high Q / V near EPs can be used to achieve circularly polarized quantum light sources and explore EP modified quantum optical effects in cavity quantum electrodynamics systems.

Combining theory and computation, we explore the Goos–Hänchen (GH) effect for electrons in a single-layered semiconductor microstructure (SLSM) modulated by Dresselhaus spin–orbit coupling (SOC). GH displacement depends on electron spins thanks to Dresselhaus SOC, therefore electron spins can be separated from the space domain and spin-polarized electrons in semiconductors can be realized. Both the magnitude and sign of the spin polarization ratio change with the electron energy, in-plane wave vector, strain engineering and semiconductor layer thickness. The spin polarization ratio approaches a maximum at resonance; however, no electron-spin polarization occurs in the SLSM for a zero in-plane wave vector. More importantly, the spin polarization ratio can be manipulated by strain engineering or semiconductor layer thickness, giving rise to a controllable spatial electron-spin splitter in the field of semiconductor spintronics. [ABSTRACT FROM AUTHOR]

The photocatalytic reduction of CO2 into hydrocarbons is a promising solution for the energy crisis and greenhouse gas emissions. Thus, the fabrication and development of a new type of photocatalyst is of great importance for the practical application of CO2 reduction. Herein, we report a facile synthesis of Zn2SnO4 (ZTO) microspheres doped with Co3+ ions or Ni3+ ions. The doped Co3+/Ni3+ ions substitute the lattice Zn/Sn ions. DFT calculations and experimental results reveal that the doped Co3+/Ni3+ ions would induce new doping energy levels in the band gap, extend the light response from the UV to the visible region, and separate the charge carriers. As a result, compared with pure ZTO, the photocatalytic activity of a CO2 reduction into CH4 is significantly improved for Co-doped ZTO (Co-ZTO) and Ni-doped ZTO (Ni-ZTO).

Compounds comprising S–S bonds serve as significant pharmacological scaffolds in medicinal chemistry and natural products. We have devised an efficient electrochemical method for the construction of asymmetric disulfide bonds, leading to the synthesis of unsymmetric thiosulfonates. Compared with existing synthesis methods, our work not only avoids the use of metals and oxidants, but also realizes the operation of a one-pot three-component method, which makes this strategy extremely attractive. [ABSTRACT FROM AUTHOR]

Objectives Precision Robotics’ Sirius Robotic Flexible Endoscopic System is a new, fully integrated, compact three-dimensional laparoscopic camera system with a disposable single-use flexible tip that can change its viewing direction. This IDEAL Stage 1 and 2a study assessed its safety, reliability and potential efficacy particularly for single incision laparoscopic surgery and vaginal natural orifice transluminal endoscopic surgery.Design Prospective single-institution, single-surgeon study.Setting The study was conducted in a multispecialty hospital.Participants Women aged 18–70 years scheduled for gynecological laparoscopic surgery were invited to participate. An information sheet and consent was available for the women and an informed consent was obtained. Thirteen participants completed this study.Interventions The laparoscopic procedures were done in the usual manner. The only difference was the Sirius System was used in place of the conventional laparoscope. All other procedures and instruments remained the same.Main outcome measures Primary outcome was the proportion of women who successfully completed the intended procedure using the Sirius System without conversion to another camera system, camera users and surgeon’s view and experience, and iterations and modifications to the system. Secondary outcomes were the incidence of intraoperative and postoperative complications during the first 6 weeks following surgery, and duration of surgery.Results 85% (11/13) of women had their procedure completed successfully using the Sirius System. Two women required immediate conversion to the conventional laparoscope due to technical issues. There were no intraoperative complications. Users agreed that the improved field of view was beneficial for laparoscopic surgery. Iterative improvements were made in the imaging quality, user interface and manufacturing quality.Conclusions Sirius System has early indications for safety and efficacy for intermediate and major minimally invasive laparoscopic procedures in gynecology. Further studies are needed to confirm it can replace a conventional laparoscope in the surgical workflow.Trial registration number NCT05048407.

Surface-enhanced Raman scattering (SERS) was considered a potential spectroscopic technique for applications of molecular detection and has drawn great research interest during the past decade. So far, fabrications of cost-effective SERS substrates with high sensitivity and stability and the corresponding enhanced mechanisms are always among the list of research topics, although great progress has been made. In this work, Au particles were decorated on Si, ZnO film and ZnO nanorod arrays simultaneously by an economical method of ion sputtering, generating three kinds of SERS substrates for R6G detection. The morphology difference of Au particles on different samples and the consequent influence on Raman scattering were studied. The experiment results exhibited that substrates with Au particles decorated on ZnO nanorods had the highest Raman enhancement factor. Furthermore, multi-effect enhanced mechanisms summarized as localized surface plasmon resonance (LSPR) filed coupling, electron transferring induced by LSPR of Au particles and whispering gallery mode (WGM) effect of the ZnO cavity were presented. This work provides a convenient and efficient method of fabricating SERS substrates and indicates that such proper metal/semiconductor composite structures are promising candidates for SERS applications.

Objective To explore the effect of poly (ADP-ribose) polymerase-1 (PARP-1) on mitochondrial DNA (mtDNA) damage induced by rotenone in rat adrenal medulla pheochromocytoma PC12 cells. Methods PC12 cells were treated with various dose of rotenone. The mtDNA common deletion (CDs) was determined by TaqMan assay, and mtDNA copy number was detected by quantitative polymerase chain reaction (qPCR). Western blotting was performed to detect the protein levels of PARP-1 in whole cell and mitochondria. After the rotenone exposed PC12 cells were treated with PJ34 (PARP-1 selective inhibitor), cell viability was detected by CCK-8 assay, mitochondrial membrane potential was examined by TMRM staining, intracellular reactive oxygen species (ROS) level was tested by 2, 7-dichlorofluorescin diacetate (DCFH-DA) probe. Results TaqMan and qPCR assays showed that rotenone treatment induced increased mtDNA deletion and decreased mtDNA copy number in PC12 cells when compared to control cells (P < 0.05). Meanwhile, PARP-1 was activated by rotenone treatment in the whole cells and mitochondria, and Western boltting showed that the protein level of PARP-1 was upregulated in a dose-dependent manner. Furthermore, compared with the rotenone group, PJ34 pretreatment enhanced the cell viability significantly in PC12 cells (P < 0.05), abolished mtDNA CDs and increased mtDNA copy number (P < 0.05). Additionally, PJ34 pretreatment caused the improvement of mitochondrial membrane potential and reduced ROS production when compared with the rotenone cells(P < 0.05). Conclusion Rotenone induces mitochondrial DNA damage, which further activates the expression of PARP-1 protein, especially mitochondria in PC12 cells. And PJ34, as the PARP-1 selective inhibitor has a protective effect on rotenone-induced mitochondrial DNA damage in PC12 cells.

Automatic video tracking has become a standard tool for investigating the social behaviour of insects. The recent integration of computer vision in tracking technologies will probably lead to fully automated behavioural pattern classification within the next few years. However, many current systems rely on offline data analysis and use computationally expensive techniques to track pre-recorded videos. To address this gap, we developed BACH (Behaviour Analysis maCHine), a software that performs video tracking of insect groups in real time. BACH uses object recognition via convolutional neural networks and identifies individually tagged insects via an existing matrix code recognition algorithm. We compared the tracking performances of BACH and a human observer (HO) across a series of short videos of ants moving in a two-dimensional arena. We found that BACH detected ant shapes only slightly worse than the HO. However, its matrix code-mediated identification of individual ants only attained human-comparable levels when ants moved relatively slowly, and fell when ants walked relatively fast. This happened because BACH had a relatively low efficiency in detecting matrix codes in blurry images of ants walking at high speeds. BACH needs to undergo hardware and software adjustments to overcome its present limits. Nevertheless, our study emphasizes the possibility of, and the need for, further integrating real-time data analysis into the study of animal behaviour. This will accelerate data generation, visualization and sharing, opening possibilities for conducting fully remote collaborative experiments.

We theoretically explore to separate electron-spins by dwell time of electrons through a magnetic microstructure with a δ-doping, which is fabricated on surface of InAs/AlxIn1-xAs heterostructure by patterning a ferromagnetic (FM) stripe. It is shown that dwell time is spin related due to both spin-field interaction and broken symmetry. It is also shown that spin-polarized dwell time can be manipulated structurally because of δ-doping dependent effective potential. Therefore, electron spins can be separated in time dimension and such a magnetic microstructure can serve as a controllable temporal spin splitter.