Single-atomic Pt sites anchored on defective Ti0_(2) nanosheets as a superior photocatalyst for hydrogen evolution

Single-atomic site catalysts have drawn considerable attention because of their maximum atom-utilization efficiency and excellent catalytic activity.In this work,a highly active single-atomic Pt site photocatalyst was synthesized through employing defective Ti0_(2) nanosheets as solid support for photo-catalytic water splitting.It indicated that the surface oxygen vacancies on defective Ti0_(2) nanosheets could effectively stabilize the single-atomic Pt sites through constructing a three-center Ti-Pt-Ti structure.The Ti-Pt-Ti structure can hold the stability of isolated single-atomic Pt sites and facilitate the separation and transfer of photoinduced charge carriers,thereby greatly improving the photocatalytic H2 evolution.Notably,our synthesized photocatalyst exhibited a remarkably enhanced H2 evolution performance,and the H2 production rate is up to 13460.7μmol h^(-1)·g^(-1),which is up to around 29.0 and 4.7 times higher than those of Ti0_(2) nanosheets and Pt nanoparticles-Ti0_(2).In addition,a plausible enhanced reaction mechanism was also proposed combining with photo-electrochemical characterizations and density functional theoiy(DFT)calculation results.Ultimately,it is believed that this work highlights the benefits of a single-site catalyst and paves the way to rationally design the highly active and stable single-atomic site photocatalysts on metal oxide support.

Multiple lines of evidence confirm that the critically endangered Blue-crowned Laughingthrush(Garrulax courtoisi)is an independent species

The taxonomy of the Blue-crowned Laughingthrush(Garrulax courtoisi)and its relationship with the Yellowthroated Laughingthrush(G.galbanus)and G.c.simaoensis,a range-restricted subspecies in China,has not been fully elucidated.So the taxonomic status and system evolution of the three taxa G.courtoisi,G.galbanus and G.c.simaoensis need to be reclarified.Two gene sequences myoglobin(MYO)and the mitochondrial cytochrome coxidase subunit I(COI)were combined to investigate the phylogenetic relationships among courtoisi,simaoensis and galbanus,genetic data,combining with morphological,ecological and acoustic data were used to comb out the classification status and divergence level of the three taxa.Significant genetic and morphological differentiations(body size and plumage coloration)were detected between courtoisi and galbanus.However,no notable and reliable differences between the courtoisi and simaoensis were detected.The courtoisi,simaoensis and galbanus are clearly isolated in geographical distribution as a result of differing altitudes,climate conditions and habitats.The courtoisi has characteristic preference for nest location compared with galbanus.In addition,the results of song analysis also indicated that there are differences in maximum frequency between courtoisi and galbanus.G.courtoisi was confirmed to be an independent species based on genetic,morphological,geographical,ecological and vocal characteristics,and the validity of simaoensis as a subspecies still need more evidence.This study further confirmed the high conservation value of Blue-crowned Laughingthrush.In addition,due to the genetic differences between Simao and Wuyuan populations,this should be fully considered in future protection strategies.

Ultracompact silicon on-chip polarization controller

On-chip polarization controllers are extremely important for various optical systems.In this paper,a compact and robust silicon-based on-chip polarization controller is proposed and demonstrated by integrating a special polarization converter and phase shifters.The special polarization converter consists of a 1×1 Mach–Zehnder interferometer with two polarization-dependent mode converters at the input/output ends.When light with an arbitrary state of polarization(SOP)is launched into the chip,the TE_(0)and TM_(0)modes are simultaneously excited.The polarization extinction ratio(PER)and the phase difference for the TE_(0)∕TM_(0)modes are tuned by controlling the first phase shifter,the polarization converter,and the second phase shifter.As a result,one can reconstruct the light SOP at the output port.The fabricated polarization controller,as compact as~150μm×700μm,exhibits an excess loss of less than 1 dB and a record PER range of>54 dB for arbitrary input light beams in the wavelength range of 1530–1620 nm.

医源性损伤致肋间动脉破裂出血介入治疗2例

胸腔穿刺术主要用于胸腔积液诊断和气胸、胸腔积液的治疗,该手术操作的典型并发症包括气胸、出血(包括血胸)和复张性肺水肿^([1])。胸腔穿刺引起肋间动脉损伤造成大出血为罕见的并发症;文献中报道的医源性损伤病例相对较少,既往的报道主要为外科手术的并发症^([2])。对肋间动脉大出血的及时处理很重要,我们将2例胸腔穿刺术致肋间动脉大出血成功行介入止血(1例明胶海绵栓塞及1例弹簧圈栓塞)的病例报道如下。

Identification and characterization of extrachromosomal circular DNA in the silk gland of Bombyx mori

The silk gland cells of silkworm are special cells which only replicate DNA in the nucleus without cell division throughout the larval stage. The extrachromosomal circular DNAs (eccDNAs) have not yet been reported in the silk gland of silkworms. Herein, we have explored the characterization of eccDNAs in the posterior silk gland of silkworms. A total of 35 346 eccDNAs were identified with sizes ranging from 30 to 13 569 549 bp. Motif analysis revealed that dual direct repeats are flanking the 5′ and 3′ breaking points of eccDNA. The sequences exceeding 1 kb length in eccDNAs present palindromic sequence characteristics flanking the 5′ and 3′ breaking points of the eccDNA. These motifs might support possible models for eccDNA generation. Genomic annotation of the eccDNA population revealed that most eccDNAs (58.6%) were derived from intergenic regions, whereas full or partial genes were carried by 41.4% of eccDNAs. It was found that silk protein genes fib-H, fib-L, and P25, as well as the transcription factors SGF and sage, which play an important regulatory role in silk protein synthesis, could be carried by eccDNAs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses showed that the genes carried by eccDNAs were mainly associated with the development and metabolism-related signaling pathways. Moreover, it was found that eccDNAfib-L could promote the transcription of fib-L gene. Overall, the results of the present study not only provide a novel perspective on the mechanism of silk gland development and silk protein synthesis but also complement previously reported genome-scale eccDNA data supporting that eccDNAs are common in eukaryotes.

Enhancement of silicon sub‑bandgap photodetection by helium‑ion implantation

Silicon sub-bandgap photodetectors can detect light at the infrared telecommunication wavelengths but with relatively weak photo-response.In this work,we demonstrate the enhancement of sub-bandgap photodetection in silicon by helium-ion implantation,without afecting the transparency that is an important benefcial feature of this type of photodetectors.With an implantation dose of 1×10^(13)ions/cm^(2),the minimal detectable optical power can be improved from−33.2 to−63.1 dBm,or,by 29.9 dB,at the wavelength of 1550 nm,and the photo-response at the same optical power(−10 dBm)can be enhanced by approximately 18.8 dB.Our work provides a method for strategically modifying the intrinsic trade-of between transparency and strong photo-responses of this type of photodetectors.

Impact assessment of river sand resource shortage under different policy scenarios in China

由于建筑业的蓬勃发展,每年在中国生产的混凝土占比全球一半以上,大量的建设一定程度上导致了河砂的短缺。此外,近年来河砂资源的自然补给速度超过了人类对河砂的开采速度,导致河砂自然资源的枯竭。河砂已成为仅次于水资源的第二大消费品,居高不下的河砂需求导致的过量开采影响了河岸地貌、碳排放、生态环境、国际贸易甚至引发国际争端。为了对我国河砂资源短缺问题提出可行的应对策略,收集了中国用于建筑的河砂数据和其他相关数据,并建议立即采取有效的政策措施以保护河砂资源、严格采砂管理。专业的解决方案可以概括为“5Rs”原则,包括减少(Reduce)、回收(Recycle)和再利用(Reuse)、替换(Replace)和恢复(Recover)。本文初步建立了系统动态模型,预测了河砂短缺的趋势,结果表明河砂的供需缺口将达63%,并在模型中检验了三种政策情景的影响,单一政策情景下的河砂供需差距可以缩小到35%,而采用所有政策的情景下,基本可以解决河砂供需矛盾(缩小到4%)。此外,本文建议从结构和材料、政策措施和国际联盟等方面采取相应措施,以实现建筑业等相关产业的可持续发展,促进人与自然的和谐共处。

Superconducting nanowire single-photon detectors:recent progress

Research of superconducting nanowire singlephoton detectors(SNSPDs) has been progressing rapidly in recent years. The combined properties of high efficiency,low noise, and fast speed of SNSPDs permit its applications ranging from long-distance quantum teleportation to moonto-earth optical communications. Here we briefly discussed recent progress of SNSPDs, in particular(1) tungstensilicide SNSPDs,(2) waveguide-integrated SNSPDs, and(3) a few applied demonstrations.

The Notch pathway attenuates burn-induced acute lung injury in rats by repressing reactive oxygen species

Background:Acute lung injury(ALI)is a common complication following severe burns.The underlying mechanisms of ALI are incompletely understood;thus,available treatments are not sufficient to repair the lung tissue after ALI.Methods:To investigate the relationship between the Notch pathway and burn-induced lung injury,we established a rat burn injury model by scalding and verified lung injury via lung injury evaluations,including hematoxylin and eosin(H&E)staining,lung injury scoring,bronchoalveolar lavage fluid and wet/dry ratio analyses,myeloperoxidase immunohistochemical staining and reac-tive oxygen species(ROS)accumulation analysis.To explore whether burn injury affects Notch1 expression,we detected the expression of Notch1 and Hes1 after burn injury.Then,we extracted pulmonary microvascular endothelial cells(PMVECs)and conducted Notch pathway inhibition and activation experiments,via aγ-secretase inhibitor(GSI)and OP9-DLL1 coculture,respectively,to verify the regulatory effect of the Notch pathway on ROS accumulation and apoptosis in burn-serum-stimulated PMVECs.To investigate the regulatory effect of the Notch pathway on ROS accumulation,we detected the expression of oxidative-stress-related molecules such as superoxide dismutase,nicotinamide adenine dinucleotide phosphate(NADPH)oxidase(NOX)2,NOX4 and cleaved caspase-3.NOX4-specific small interfering RNA(siRNA)and the inhibitor GKT137831 were used to verify the regulatory effect of the Notch pathway on ROS via NOX4.Results:We successfully established a burn model and revealed that lung injury,excessive ROS accumulation and an inflammatory response occurred.Notch1 detection showed that the expression of Notch1 was significantly increased after burn injury.In PMVECs challenged with burn serum,ROS and cell death were elevated.Moreover,when the Notch pathway was suppressed by GSI,ROS and cell apoptosis levels were significantly increased.Conversely,these parameters were reduced when the Notch pathway was activated by OP9-DLL1.Mechanistically,the inhibition of NOX4 by siRNA and GKT137831 showed that the Notch pathway reduced ROS production and cell apoptosis by downregulating the expression of NOX4 in PMVECs.Conclusions:The Notch pathway reduced ROS production and apoptosis by downregulating the expression of NOX4 in burn-stimulated PMVECs.The Notch-NOX4 pathway may be a novel therapeutic target to treat burn-induced ALI.

Photocatalytic properties of hierarchical BiOXs obtained via an ethanol-assisted solvothermal process

In this study, bismuth oxyhalide（Bi OXs（X_Cl, Br, I）） semiconductors were prepared by a simple solvothermal method, with ethanol serving as solvent and a series of tetrabutylammonium halide surfactants as halogen sources. Under identical synthetic conditions, Bi OBr was more readily constructed into regular flower-like hierarchical architectures. The photocatalytic properties of the materials were studied by monitoring the degradation of rhodamine B（Rh B）,with visible light absorption, and colorless salicylic acid（SA）. It was found that both Rh B and SA were rapidly degraded on the surface of Bi OBr. Bi OCl was rather active for the degradation of Rh B,but ineffective toward the degradation of SA. However, neither Rh B nor SA could be degraded effectively in the case of Bi OI. Further experiments such as UV–visible spectroscopy and detection of U OH and O2 Uradicals suggest that the electronic structure of the Bi OX photocatalysts is responsible for the difference in their activities.

Superconducting nanowire multi-photon detectors enabled by current reservoirs

Single-photon detectors are ubiquitous devices in quantum-photonic-based communication,computation,metrology,and sensing.In these applications,N-fold coincidence photon counting is often needed,for example,to characterize entanglement.However,N-fold coincidence photon counting typically requires N individual singlephoton detectors and associated bias and readout electronics,and these resources could become prohibitive if N goes large and the detectors need to work at cryogenic temperatures.Here,to break this limit on N,we propose a device architecture based on N cascaded photosensitive superconducting nanowires and one wider nanowire that functions as a current reservoir.We show that by strategically designing the device,the network of these superconducting nanowires can work in a synergic manner as an n-photon detector,where n can be from 1 to N,depending on the bias conditions.We therefore name the devices of this type superconducting nanowire multi-photon detectors(SNMPDs).In addition to its simple one-port bias and readout circuitry,the coincidences are counted internally in the detector,eliminating the need for external multi-channel,time-correlated pulse counters.We believe that the SNMPDs proposed in this work could open avenues towards conveniently measuring high-order temporal correlations of light and characterizing multi-photon entanglement.

Synthesis of Sn nanocluster@carbon dots for photodynamic therapy application

Recently,photodynamic therapy(PDT)has been extensively applied in clinical and coadjuvant treatment of various kinds of tumors.However,the photosensitizer(PS)of PDT still lack of high production of singlet oxygen(^(1)O_(2)),low cytotoxicity and high biocompatibility.Herein,we propose a facile method for establishing a new core-shell structured Sn nanocluster@carbon dots(CDs)PS.Firstly,Sn^(4+)@S-CDs complex is synthesized using the sulfur-doped CDs(S-CDs)and SnCl4 as raw materials,and subsequently the new PS(Sn nanocluster@CDs)is obtained after vaporization of Sn4+@S-CDs solution.Remarkably,the obtained Sn nanocluster@CDs show an enhanced fluorescence as well as a higher ^(1)O_(2) quantum yield(QY)than S-CDs.The high ^(1)O_(2) QY(58.3%)irradiated by the LED light(400-700 nm,40 mW/cm^(2)),induce the reduction of 4 T1 cancer cells viability by 25%.More intriguingly,no visible damage happens to healthy cells,with little impact on liver tissue due to renal excretion,both in vitro and in vivo experiments demonstrate that Sn nanocluster@CDs may become a promising PS,owning a high potential for application in PDT.

Dynamic detection method for falling ears of maize harvester based on improved YOLO-V4

Traditional maize ear harvesters mainly rely on manual identification of fallen maize ears,which cannot realize real-time detection of ear falling.The improved You Only Look Once-V4(YOLO-V4)algorithm is combined with the channel pruning algorithm to detect the dropped ears of maize harvesters.K-means clustering algorithm is used to obtain a prior box matching the size of the dropped ears,which improves the Intersection Over Union(IOU).Compare the effect of different activation functions on the accuracy of the YOLO-V4 model,and use the Mish activation function as the activation function of this model.Improve the calculation of the regression positioning loss function,and use the CEIOU loss function to balance the accuracy of each category.Use improved Adam optimization function and multi-stage learning optimization technology to improve the accuracy of the YOLO-V4 model.The channel pruning algorithm is used to compress the model and distillation technology is used in the fine-tuning of the model.The final model size was only 10.77%before compression,and the test set mean Average Precision(mAP)was 93.14%.The detection speed was 112 fps,which can meet the need for real-time detection of maize harvester ears in the field.This study can provide technical reference for the detection of the ear loss rate of intelligent maize harvesters.

One-pot synthesis of CoO-ZnO/rGO supported on Ni foam for high-performance hybrid supercapacitor with greatly enhanced cycling stability

The high specific capacitance along with good cycling stability are crucial for practical applications of supercapacitors,which always demands high-performance and stable electrode materials.In this work,we report a series of ternary composites of CoO-ZnO with different fractions of reduced graphene oxide(rGO)synthesized by in-situ growth on nickel foam,named as CZG-1,2 and 3,respectively.This sort of binder-free electrodes presents excellent electrochemical properties as well as large capacitance due to their low electrical resistance and high oxygen vacancies.Particularly,the sample of CZG-2(CoO-ZnO/rGO 20 mg)in a nanoreticular structure shows the best electrochemical performance with a maximum specific capacitance of 1951.8 F/g(216.9 mAh/g)at a current intensity of 1 A/g.The CZG-2-based hybrid supercapacitor delivers a high energy density up to 45.9 Wh/kg at a high power density of 800 W/kg,and kept the capacitance retention of 90.1%over 5000 charge-discharge cycles.