Ultrafast all‐optical switching, possessing the unique function of light controlling light, is an essential component of on‐chip ultrafast optical connection networks as well as integrated logic ...computing chips. Ultrafast all‐optical switching has attracted enormous research interests, the latest great developments of which have also yield progress in nanophotonics, integrated optics, nonlinear optics, material science, and optical communications, and so on. This review summarizes the fundamental realization principles, novel configurations, fancy materials, improved performance indexes, and ameliorated trigger method (transitioning from a traditional impractical free‐space‐vertical trigger to a more practical on‐chip trigger) of ultrafast all‐optical switching. Not only a systematic discussion of the current state‐of‐the art is provided, but also a brief outlook on the remaining challenges in the pursuit of the application of a practical on‐chip ultrafast all‐optical switching is also afforded.
Ultrafast all‐optical switching, a core unit in on‐chip optical interconnection and ultrahigh speed information photonic chips, can control the propagation state of signal light. In this review, a summary of the fundamental concepts and mechanisms, composed structures, materials and outstanding performance indexes in all‐optical switching is provided. Different configurations are compared and an overview of the current research status and remaining challenges is given.
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•Electrochemical mineralization of PCP was investigated over Ti/SnO2–Sb electrodes.•Degradation of PCP over Ti/SnO2–Sb electrodes follows pseudo-first-order kinetics.•Degradation of ...PCP is accompanied by dechlorination and protons generation.•TOC and toxicity decrease rapidly with electrochemical removal of PCP.
Electrochemical degradation of pentachlorophenol (PCP) in aqueous solution was investigated over Ti/SnO2–Sb electrodes prepared by sol–gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements were used to characterize the physicochemical properties of the electrodes. The electrochemical degradation of PCP followed pseudo-first-order kinetics. The main influencing factors, including the types of supporting electrolyte (i.e., NaClO4, Na2SO4, Na2SO3, NaNO3, and NaNO2), initial concentrations of PCP (5–1000mgL−1), pH values (3.0–11.0), and current densities (5–40mAcm−2) were evaluated. The degradation and mineralization ratios of 100mgL−1 of PCP achieved >99.8% and 83.0% after 30min electrolysis with a 10mmolL−1 Na2SO4 at a current density of 10mAcm−2, respectively. The corresponding half-life time (t1/2) was 3.94min. The degradation pathways that were involved in dechlorination, protons generation, and mineralization processes were proposed based on the determination of total organic carbon, chloride, and intermediate products (i.e., low chlorinated phenol and some organic acids). The toxicity of PCP and its intermediates could be reduced effectively by electrolysis. These results showed that electrochemical technique could achieve a significant mineralization rate in a short time (<30min), which provided an efficient way for PCP elimination from wastewater.
Spin-orbit interaction (SOI) of light has attracted enormous interest for its potential applications in controlling light at nanoscale and holds promise for future optical information technology and ...optoelectronics. In particular, the transverse spin in evanescent waves is regarded as distinct manifestation of SOI and an emerging candidate for miniaturizing optoelectronic circuits. However, further application has been hampered by the inability to conveniently generate light field with configurable transverse spin. Here, we present a simple method to generate free-space light field with arbitrary transverse spin utilizing vector beam interference and numerically demonstrate the configurable spin orbital coupling in nanophotonic waveguide. Chiral waveguide with excellent extinction ratio up to 42 dB is achieved in our simulation. The propagating direction of guided mode can be fully controlled via tuning the ellipticity of transverse spin. The device is compatible with existing integrated nanophotonic devices and may find valuable applications in future optical information processing and optical communication technology.
We investigated the release behaviors and reaction reactivities of gaseous products during CO
2
gasification of three chars (Guanghui char, Hongshagang char, and Shenmu char) and graphite using ...thermogravimetric–mass spectrometry. The three chars with different sulfur contents had similar release behaviors. CO was the primary gaseous product, while SO
2
was the main gaseous sulfur product. CO forms through the reaction between carbon and CO
2
. The temperature ranges at which H
2
and COS evolved are similar to that of CO, and both H
2
S and SO
2
were released at around 1100 °C. For the same gas, the differences in release behaviors were mainly due to the reactivity of the evolution reactions. Alkali mineral species had a catalytic effect on char gasification, while the increasing degree of graphitization tended to increase gasification reaction resistance. Larger surface area resulted in decreased reaction resistance at the initial stage of the gasification reaction. The most important factor influencing sulfur release reactivity was gasification activity rather than sulfur species in char. Moreover, acidic minerals may accelerate the release of sulfur.
The construction of large-scale integrated photonic circuit cannot be separated from the important role played by silicon-based optoelectronic devices. As a basic and important link in on-chip photon ...propagation, beam splitting is of great significance for the efficient utilization of sources and the compact integration of optoelectronic devices. It is widely used in power splitting, polarization separation, wavelength division multiplexing and other scenarios. This paper reviews the on-chip beam splitting methods in recent years, which are mainly divided into the following categories: y-branch, multimode interference coupling, directional coupling, and inverse design. This paper introduces their research status, including optimization design methods, functions and applications in large-scale quantum chips and optoelectronic hybrid integration, looking forward to providing a reference for the further research of beam splitting methods and the wide application of beam splitters in the frontier field in the future.
At present, most atomic spin precession detection schemes use discrete optical elements, which leads to bulky detection systems. However, chip-based spin precession detection schemes lack modulation, ...resulting in lower detection sensitivity. In this paper, we propose and simulatively demonstrate an integrated atomic spin precession detection scheme using an on-chip Mach-Zehnder-like interferometer. An on-chip polarization sorter is designed, with contrast ratio of 24dB and coupling efficiency of 16.8% at 795 nm. With this device, linearly polarized probe light that experienced optical rotation can be split and coupled into two waveguide arms of the interferometer. To avoid the effect of low frequency noise, our scheme uses a micro-heater to modulate the phase difference signal, allowing for high sensitivity detection. The whole detection system can reach micron size, which provides a practical new technique for high precision atomic sensors that can be integrated into chips.
•Sliding bed joint isolation technique for ashlar stone masonry was proposed.•Experimental and analytical study carried out to evaluate isolation performance.•Steel plate-steel plate interface found ...to be suitable as sliding bed joint.•Stable behavior achieved by leveling discretely distributed plate interfaces.•Simplified expressions to predict acceleration response spectrum proposed.
An isolation technique using sliding bed joint for seismic response control of ashlar stone masonry buildings was developed and investigated in this paper. Eight triplet specimens were tested under cyclic loads to identify suitable interface material for the sliding bed joint. Further, four stone masonry wall specimens were tested to investigate the frictional performance of the sliding bed joint. The sliding friction coefficient of stainless steel plate-stainless steel plate interface was about 0.17 and found to be insensitive to sliding displacement and the level of compressive stress. The proposed interface was found suitable for the sliding bed joint application. Stable frictional performance of sliding bed joint in practical engineering buildings could be achieved by leveling the interface of each group of the discrete distribute steel plates (two pairs of steel plates equidistantly adhesive on one stone block). A two-degrees-of-freedom mathematical model was adopted to investigate the isolation performance of stone structure's sliding bed joint. No sliding displacement was observed in the isolated stone structures in the case of frequent level earthquake. On the other hand, the average absolute acceleration response in the case of design and rare level earthquakes was significantly reduced compared to fixed base structures. The maximum average sliding displacement of isolated stone structures considered was about 71 mm which is within the half-length of the steel plate. Simple expressions were proposed to predict the average absolute acceleration spectrum of isolated stone structures. The experimental and analytical results provided reference for the application of the sliding bed joint in the stone masonry buildings.
Excitotoxicity plays a central role in the neuronal damage during ischemic stroke. Although growing evidence suggests that activation of extrasynaptic NMDA receptors initiates neuronal death, no ...direct evidence demonstrated their activation during ischemia. Using rat hippocampal slices, we detected oxygen–glucose deprivation (OGD) induced slow inward currents (SICs) mediated by extrasynaptic NMDA receptors in CA1 pyramidal neurons. Moreover, Ca2+ chelator BAPTA dialysis into astrocytic network decreased the frequency of OGD induced SICs, indicating that the activation of extrasynaptic NMDA receptors depended on astrocytic Ca2+ activity. To further demonstrate the importance of astrocytic Ca2+ activity, we tested hippocampal slices from inositol triphosphate receptor type 2 (IP3R2) knock-out mice which abolished the astrocytic Ca2+ activity. As expected, the frequency of OGD induced SICs was reduced. Using two-photon Ca2+ imaging, we characterized the astrocytic Ca2+ dynamics. By controlling Ca2+ level in the individual astrocytes using targeted photolysis, we found that OGD facilitated the propagation of intercellular Ca2+ waves, which were inhibited by gap junction blocker carbenoxolone (CBX). CBX also inhibited the Ca2+ activity of the astrocytic network and decreased the SIC frequency during OGD. Functionally, the infarct volumes from brain ischemia were reduced in IP3R2 knock-out mice and in rat intracerebrally delivered with CBX. Our results demonstrate that enhanced Ca2+ activity of the astrocytic network plays a key role on the activation of extrasynaptic NMDA receptors in hippocampal neurons, which enhances brain damage during ischemia.
•Extrasynaptic NMDA receptors are activated during ischemia.•Astrocytic Ca2+ elevations mediate the activation of extrasynaptic NMDA receptors.•Ischemia evokes the intercellular Ca2+ waves (ICWs) in astrocytes.•ICW propagation promotes the activation of extrasynaptic NMDA receptors during ischemia.•IP3R2 knock-out mice exhibit ischemic tolerance.
Under investigation in this paper are the coupled nonlinear Schrödinger (CNLS) equations with dissipation terms by the Hirota method, which are better than the formal Schrödinger equation in ...eliciting optical solitons. The bilinear form has been constructed, via which multisolitons and breathers are derived. In particular, the three-bright soliton solution and breathers are derived and simulated via some pictures. The propagation characters are analysed with the change of the parameters.
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