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Time-of-flight single-photon counting laser ranging offers an important tool for remote sensing and imaging. However, limited by the temporal properties of a single-photon detection and counting system, it encounters a challenge for high-resolution and high-precision distance metrology. Here, we incorporated dual-comb based laser ranging, an enabling technique for rapid distance measurements with high precision and large range ambiguity, with time-correlated single-photon counting (TCSPC) technology and demonstrated its feasibility for precise laser ranging under a photon-starved condition. Based on interferometric measurements of two asynchronous 2.8-pW, 25-GHz electro-optic laser combs with TCSPC, micrometer-level ranging precision was achieved for consistent distance measurements (a stand-off distance of 15.6 m) over several days. New opportunities might open up for high-resolution and high-precision single-photon counting laser ranging.

Electrochemical carbon dioxide reduction reaction (CO2RR) powered by renewable electricity offers an attractive approach to reduce carbon emission and at the same time produce valuable chemicals/fuels. To design efficient CO2 reduction electrocatalyst, it is important to understand the structure-activity relationship. Herein, we design a series of single Co atoms electrocatalysts with well-defined active sites electronic structures, which exhibit outstanding CO2RR activity with controllable selectivity to CO. Experimental and density functional theory (DFT) calculation studies show that introducing nitro (amino) ligand next to single Co atom catalytic center with electron-withdrawing (electron-donating) capability favors (hinders) CO2 reduction catalysis. This work provides an in-depth understanding of how functional ligand affects the splitting of transition metal 3d electron orbital, thereby changing the electron transfer from transition metal active site to CO2, which is closely related to the Gibbs free energy of the rate-determining step (CO2+e−+*→*CO2−).

Selective enrichment and purification of histidine (His)-rich protein from complex mixtures is vital to satisfy the requirements of proteomic and diagnostic applications, but it still remain a chal...

Although multiple advanced antibacterial and sterilization materials are available, bacterial infections still remain a big challenge in wound healing as they usually induce serious complications and cannot be thoroughly eliminated. Herein, we report an antibacterial film composed of the naturally derived polysaccharide chitosan (CS) and a copper metal-organic framework (HKUST-1) as a multifunctional platform for antibacterial and local infection therapy applications. As expected, the as-prepared HKUST-1/CS film possessed versatile abilities such as slow release of copper ions and reduced cytotoxicity; moreover, fluorescent staining and morphological changes of the bacteria treated with the HKUST-1/CS film confirmed the antibacterial activity of the fabricated film. Furthermore, in vivo results revealed that the HKUST-1/CS film could simultaneously kill bacteria and promote vessel regeneration; this resulted in an enhanced wound closure rate during the local infection therapy process. Overall, these results highlight that the HKUST-1/CS film exhibits significant potential as a suitable and promising wound dressing.

We propose and experimentally demonstrate single-pixel photon counting imaging based on dual-comb interferometry at 1550 nm. Different from traditional dual-comb imaging, this approach enables imaging at the photon-counting regime by using single-photon detectors combined with a time-correlated single-photon counter to record the returning photons. The illumination power is as low as 14 pW, corresponding to 2.2 × 10−3 photons/pulse. The lateral resolution is about 50 μm. This technique paves the way for applying dual-comb in remote sensing and imaging.

In this Letter, we utilize an acoustic-optic frequency shifter in a feedforward manner for automatic interpolation of dual-comb spectroscopy, where frequency tuning can be achieved at 5.45 THz/s with the step size precisely locked to the line spacing (54.5 MHz) of a referenced optical comb without complicated electronics or control programs. Our dual-comb spectrometer involves two near-infrared electro-optic combs at 25 GHz line spacings, nonlinearly converted into the mid-infrared region, revealing fundamental absorption lines of methane gas at 54.5 MHz resolution within a spectral range from 88.04 to 89.04 THz. The method and the system may be useful in many applications, including gas sensing.

We explore the potential of combining dual-comb interferometry with single-photon detection and counting technologies for precise time-of-flight relative distance measurements with two asynchronous 25-GHz line-spacing combs at the single-photon level.

We explore the potential of femtosecond laser-induced filamentation for optical gas imaging. In a proof-of-concept experiment, non-contact three-dimensional hyperspectral imaging of an alcohol/air flame is demonstrated with high spatial and spectral resolution.

Microenvironment engineering of single-atom catalysts paves the way toward efficient electrochemical energy conversion., Single-atom catalysts (SACs) have become the most attractive frontier research field in heterogeneous catalysis. Since the atomically dispersed metal atoms are commonly stabilized by ionic/covalent interactions with neighboring atoms, the geometric and electronic structures of SACs depend greatly on their microenvironment, which, in turn, determine the performances in catalytic processes. In this review, we will focus on the recently developed strategies of SAC synthesis, with attention on the microenvironment modulation of single-atom active sites of SACs. Furthermore, experimental and computational advances in understanding such microenvironment in association to the catalytic activity and mechanisms are summarized and exemplified in the electrochemical applications, including the water electrolysis and O2/CO2/N2 reduction reactions. Last, by highlighting the prospects and challenges for microenvironment engineering of SACs, we wish to shed some light on the further development of SACs for electrochemical energy conversion.

The excessive accumulation of toxic copper species makes it imperative to develop smart dual-functional materials for the simultaneous removal and detection of Cu(II) in drinking water. In this work, novel core–shell NH2-MIL-101(Al)@ZIF-8 nanoflowers were successfully fabricated via an internal extended growth mode under the regulation of polyvinylpyrrolidone (PVP) to achieve this goal. Benefiting from the specific affinity of imidazole nitrogen in ZIF-8 toward Cu(II), the resultant NH2-MIL-101(Al)@ZIF-8 shows high adsorption capacity (526.74 mg g−1). Moreover, the fluorescence of NH2-MIL-101(Al) shows a Cu(II)-dependent change, causing this composite to possess superior selective/sensitive detection with a broad linear range (1.5–625 μM) and a low detection limit (0.17 μM) for Cu(II). Specifically, the hybrid MOF@MOF structure provides greater sensitivity as compared to the individual constituent (pristine NH2-MIL-101(Al)) and the mixed state, which is ascribed to the rational optimization of the smart adsorbent based on the following two aspects. (i) The synergistic effect of the core–shell nanostructure improves the preconcentration ability at the interface between single MOFs. (ii) The existence of the three-dimensional hierarchical nanoflower architecture (structure optimization) accelerates the mass transport and sculpts the final composite with enhanced adsorption and detection ability. These indicate that the smart NH2-MIL-101(Al)@ZIF-8 nanoflower could be an excellent candidate for the synchronous remediation and selective detection of Cu(II) in aqueous systems, which could be potentially useful in wastewater treatment and water quality monitoring.

In order to overcome the shortcoming of the TDLAS method, a partial pressure measurement method based on dual comb spectroscopy is proposed. The comb-based partial pressure measurement system comes with excellent performance in nearly all criteria: high detection sensitivity, high measurement speed, and synchronous survey of multiple-gas partial pressures. The experimental system was built in the mid-infrared band of 88.42–90.10 THz with a spectral resolution of 54.5 MHz and used for partial pressure measurement of CH4 and C2H4. Two electro-optics (EO) optical frequency combs (OFC) with a repeat frequency of ～25 GHz are spectrally interpolated to increase spectral sampling ratio using an acousto-optic frequency shifter, so that they could be utilized for high-resolution gas sensing. The measurement result demonstrates the excellent performance of this system in partial pressure measurement. The deviation of the measurement results of two gases CH4 and C2H4 from the true value are about 3%. Moreover, once the gas absorption line strength is accurately calibrated, the accuracy of partial pressure measurement will be further improved.

Accurate state estimation is a fundamental component of robotic control. In robotic manipulation tasks, as is our focus in this work, state estimation is essential for identifying the positions of objects in the scene, forming the basis of the manipulation plan. However, pose estimation typically requires expensive 3D cameras or additional instrumentation such as fiducial markers to perform accurately. Recently, Tobin et al.~introduced an approach to pose estimation based on domain randomization, where a neural network is trained to predict pose directly from a 2D image of the scene. The network is trained on computer-generated images with a high variation in textures and lighting, thereby generalizing to real-world images. In this work, we investigate how to improve the accuracy of domain randomization based pose estimation. Our main idea is that active perception -- moving the robot to get a better estimate of pose -- can be trained in simulation and transferred to real using domain randomization. In our approach, the robot trains in a domain-randomized simulation how to estimate pose from a \emph{sequence} of images. We show that our approach can significantly improve the accuracy of standard pose estimation in several scenarios: when the robot holding an object moves, when reference objects are moved in the scene, or when the camera is moved around the object., Accepted at International Conference on Robotics and Automation (ICRA) 2019

Roll profile electromagnetic control technology (RPECT) is a new strip flatness control technology. As the control element, electromagnetic sticks have a great effect on the control ability of RPECT. To improve control ability and extend service life, effective control ratio of electromagnetic stick is presented in this paper. The ratio is designed based on the structure character of electromagnetic stick, and can be used to evaluate the key parameter of electromagnetic stick. Based on the coupled FEM, the heat flux density of the roll inner hole and the temperature distribution of electromagnetic stick are analyzed for different effective control ratios; the average contact pressure between electromagnetic stick and electromagnetic control roll is studied to evaluate the change of force roll profile; the state of roll profile and the stress state of the roll are researched to analyze the comprehensive control ability. Through the verification on the roll profile electromagnetic control experimental platform, the reasonable selection range of effective control ratio, which can be used to expand the roll profile axial affected area, is from 0.5 to 0.583. In order to increase the roll crown, the selection of ηd needs to consider the current density and the optimal selection range of effective control ratio.

Despite the development of advanced photocatalysts, the practical application of photocatalytic water disinfection is still under restrictions due to the low reusability of powder photocatalysts. In this paper, we synthesized the binary composite heterojunction photocatalyst MoS2/TiO2 nanotube arrays (MoS2/TiO2 NTAs), using anodic oxidation method and hydrothermal method. The water disinfection efficiency of MoS2/TiO2 NTAs under visible light irradiation against pathogenic bacteria was up to 98.5% and still reached 92.1% after 3 times recovering and recycling. The mechanism was proven to be the seriously damage of bacterial cell membrane caused by the ROS produced from MoS2/TiO2 NTAs photocatalyst under light irradiation. In addition, we analyzed the water sample changes after material recovery by ICP-MS, and found that there is no MoS2 nanosheet falling off. This result supported the recyclable effect of MoS2/TiO2 NTAs and avoided the nanoparticles remaining in the water as much as possible. Therefore, MoS2/TiO2 NTAs composites have great application prospects in water disinfection due to their excellent photocatalytic disinfection effect, recyclability and reusability.

Reverse water gas shift (RWGS) reaction can serve as a pivotal stage in the CO2 conversion processes, which is vital for the utilization of CO2. In this study, RWGS reaction was performed over Pt/CeO2 catalysts at the temperature range of 200–500 °C under ambient pressure. Compared with pure CeO2, Pt/CeO2 catalysts exhibited superior RWGS activity at lower reaction temperature. Meanwhile, the calculated TOF and Ea values are approximately the same over these Pt/CeO2 catalysts pretreated under various calcination conditions, indicating that the RWGS reaction is not affected by the morphologies of anchored Pt nanoparticles or the primary crystallinity of CeO2. TPR and XPS results indicated that the incorporation of Pt promoted the reducibility of CeO2 support and remarkably increased the content of Ce3+ sites on the catalyst surface. Furthermore, the CO TPSR-MS signal under the condition of pure CO2 flow over Pt/CeO2 catalyst is far lower than that under the condition of adsorbed CO2 with H2-assisted flow, revealing that CO2 molecules adsorbed on Ce3+ active sites have difficult in generating CO directly. Meanwhile, the adsorbed CO2 with the assistance of H2 can form formate species easily over Ce3+ active sites and then decompose into Ce3+–CO species for CO production, which was identified by in-situ FTIR.

Deproteinization is a crucial step for the purification of polysaccharides from natural biomass. However, traditional deproteinization technologies often suffer from complicated operating processes and the usage of toxic chemical reagents. Herein, an advanced and universal deproteinization method based on dual-functional adsorbent consisted of preferential protein adsorption coating of tannic acid-FeIII (TA-FeIII) and magnetic Fe3O4 (Fe3O4@TA-FeIII, abbreviated as FTF NPs) was developed. The proposed FTF NPs showed remarkable efficiency to remove protein from Lycium barbarum L. polysaccharides (LBPs) with deproteinization ratio of 96%, higher than the typical Sevag method (85%). Detailed adsorption kinetics studies demonstrated deproteinization process reached equilibrium after 10 min, faster than other reported deproteinization adsorbents. Furthermore, FTF NPs are structurally and functionally nondestructive as regards LBPs without using organic reagents. Also, it exhibited widespread-use deproteinization performance to several common plant species. Therefore, the proposed nano-separation based on TA-FeIII complex is an advanced and universal tool to high-efficiently deproteinize plant polysaccharides.

Constructing MOFs-composite catalyst with satisfactory catalytic efficiency as well as low cost still presents a major challenge. In this work, a low-cost modular photocatalyst with controllable activity is facilely fabricated by embedding ZIF-8 nanocrystal clusters with ammonium tetrathiomolybdate (ATTM) (donated as ZIF-MS). The embedded ATTM molecules can not only serve as photocatalytic sites but also alter the nucleation and morphology of the resulted ZIF-MS, showing controllable activity for catalytic application. Under the optimized proportion of precursors, 576.52 nm ZIF-MS nanocrystal cluster composed of 24.70 nm grain, showing high activity and size selectivity for the photocatalytic degradation of environmental pollutants, was obtained. The combination of size-selectivity of structure-tunable ZIFs with high photocatalytic activity of embedded noble-free inorganic photocatalytic agent makes these ZIF-MS ideal candidates for photocatalytic applications. Keywords: Ammonium tetrathiomolybdate, MOFs, Photocatalysis, Controllable catalyst, Size-selectivity

In this paper, we experimentally investigate a rich set of Q-switching bunches in the build-up of stretched-pulse mode-locking of an erbium-doped fiber laser. Interestingly, regular clustering of periodic Q-switched mode-locking states is observed in the self-starting process. Moreover, with time-stretch spectroscopy, we record periodic pulse-to-pulse spectral evolution occurring in these turbulent and rapidly-evolving pre-mode-locking states.