Interdependence between the stock market and the bond market in one country:evidence from the subprime crisis and the European debt crisis

Background:Once a global financial crisis breaks out,the interdependence between different financial markets suddenly increases and leads to a significant contagion.Methods:With 39 countries used as samples,this paper analyzes the interdependence between the stock market and the government bond market during the crisis periods.Results:It proves that the investor focuses more on the safety of their portfolio so there is neither a flight from quality nor a positive spillover during a crisis period.When one market is safer than the other market in the same country,a flight to quality occurs between the two markets;however,when the two markets in one country are both risky,negative spillover appears between these two markets.Conclusions:This means a flight to quality from the stock market to the short-term government bond will occur more frequently than will occur from the stock market to the long-term government bond markets.In addition,a flight to quality always emerges in developed markets,while negative spillovers take place in emerging markets and in the PIIGS countries(Portugal,Italy,Ireland,Greece,and Spain,referred to hereon as“PIIGS”)in the European Debt Crisis.

A pyrene-based ratiometric fluorescent probe with a large Stokes shift for selective detection of hydrogen peroxide in living cells

Hydrogen peroxide(H2O2)plays a significant role in regulating a variety of biological processes.Dysregulation of H2O2 can lead to various diseases.Although numerous fluorescent imaging probes for H2O2 have been reported,the development of H2O2 ratiometric fluorescent probe with large Stokes shift remains rather limited.Such probes have shown distinct advantages,such as minimized interference from environment and improved signal-to noise ratio.In this work,we reported a new pyrene-based compound Py-VPB as H2O2 fluorescent probe in vitro.The probe demonstrated ratiometric detection behavior,large Stokes shift and large emission shift.In addition,the probe showed high sensitivity and selectivity towards H2O2 in vitro.Based on these excellent properties,we successfully applied Py-VPB to the visualization of exogenous and endogenous H2O2 in living cells.Cell imaging study also showed that our probe was localized in the mitochondria.We envision that the probe can provide a useful tool for unmasking the biological roles of mitochondrial H2O2 in living systems.

饮用水中的微塑料及其拉曼光谱检测技术研究进展

塑料的发明和应用已逾百年,给日常生活带来了极大的便利。塑料制品及成分经过破碎降解后形成微塑料(MPs),环境中的MPs可进入饮用水,其污染和潜在的健康危害逐渐受到重视。MPs的定性和定量检测仍处于发展阶段,拉曼光谱(RS)是目前较常用的一种较灵敏的非破坏性的无损光学分析技术。本文重点介绍了饮用水中MPs的来源、潜在危害以及RS检测的研究进展,旨在提高对饮用水中MPs污染的认知和对研发MPs检测技术的重视。

Industry-Oriented Detection Method of PCBA Defects Using Semantic Segmentation Models

Automated optical inspection(AOI)is a significant process in printed circuit board assembly(PCBA)production lines which aims to detect tiny defects in PCBAs.Existing AOI equipment has several deficiencies including low throughput,large computation cost,high latency,and poor flexibility,which limits the efficiency of online PCBA inspection.In this paper,a novel PCBA defect detection method based on a lightweight deep convolution neural network is proposed.In this method,the semantic segmentation model is combined with a rule-based defect recognition algorithm to build up a defect detection frame-work.To improve the performance of the model,extensive real PCBA images are collected from production lines as datasets.Some optimization methods have been applied in the model according to production demand and enable integration in lightweight computing devices.Experiment results show that the production line using our method realizes a throughput more than three times higher than traditional methods.Our method can be integrated into a lightweight inference system and pro-mote the flexibility of AOI.The proposed method builds up a general paradigm and excellent example for model design and optimization oriented towards industrial requirements.

通信机楼AI节能方案研究及其应用前景

本文针对通信机楼的负载、能耗和制冷系统运行状况,研究通信机楼AI节能方案,并探讨其在实际应用中的前景,以期获得节能降费和优化PUE的效果,并为相关领域的研究人员和决策者提供参考和借鉴。研究结果将有助于提高通信设施的能源效率,降低运营成本,推动通信设施的可持续发展,同时也有望为企业节省能源成本,减少对环境的影响。

霍山石斛内生真菌DHS-3、DHS-4代谢产物的高效液相研究

将已经分离得到的霍山石斛内生真菌DHS-3、DHS-4进行培养,运用高效液相色谱(HPLC)检测技术,对DHS-3、DHS-4的代谢产物进行分析比较。结果表明洗脱峰RT18.353、RT48.536,RT29.442、RT50.358分别为DHS-3、DHS-4两种菌的代谢产物与霍山石斛的共有峰,揭示霍山石斛内生真菌DHS-3、DHS-4可能产生与霍山石斛相同的物质。

变应变率下骨骼肌连续介质本构模型

目的针对不同结构耦合肌肉主被动行为无法考虑肌肉组织连续介质力学特性的问题,提出运用被动与主动耦合在同一个本构方程的方法,构建骨骼肌连续介质超弹性主被动本构模型。方法为标定被动本构模型参数,给出单轴拉伸实验方法及条件,并通过理论推导,介绍利用试验数据求解被动模型参数的具体方法。为验证主动模型的有效性,以实例对模型进行验证。结果模型预测曲线与实验输出应力拉伸比曲线具有较好的一致性,在相同应变下的情况下,被动应力和总应力最大误差仅为20、40 kPa。结论该连续介质超弹性本构模型能较好模拟骨骼肌的主被动行为,从而有利于下一步人体肌肉的建模与仿真。

Bancroft算法应用于GPS/BDS/GLONASS三系统伪距单点定位

为了提高多系统组合单点定位的运算效率,将Bancroft算法推广应用于GPS/BDS/GLONASS三系统伪距单点定位,并推导了该方法的详细计算流程,比较了Bancroft算法、最小二乘算法和组合两种算法的精度、迭代次数以及运算时间。利用实测数据进行实验,结果表明,3种算法精度相当,Bancroft算法比最小二乘算法迭代次数少,运算效率提高了38%,利用Bancroft为最小二乘算法提供初值,收敛速度加快,运算效率提高了36%。最终得出结论,Bancroft算法应用于GPS/BDS/GLONASS三系统伪距单点定位满足精度要求,且Bancroft算法对于减少迭代次数,提高运算效率有重要意义。

淬冷烈度对车轴钢组织结构及力学性能的影响

使用不同淬冷烈度的淬火介质对车轴用EA4T和35CrMo钢进行淬火处理,然后利用金相显微镜、透射电子显微镜等分析钢的组织结构,并测定其力学性能.结果表明:随着淬冷烈度的增加,EA4T和35CrMo钢在淬火后获得的马氏体组织越细小,硬度有所增加,但变化幅度不大;虽然液氮具有很高的淬冷烈度,但在淬火过程中易形成蒸汽膜而导致冷速降低,形成非马氏体组织.35CrMo钢淬火形成的马氏体为体心正方结构,其轴比c/a随着淬冷烈度的增大呈小幅度增大,碳的过饱和度随着淬冷烈度的增大而增大.35CrMo钢经不同淬冷烈度的淬火介质淬火后回火,其力学性能主要取决于回火温度,碳的过饱和度对回火钢的性能影响不显著.

非差非组合PPP-RTK:模型算法、终端样机与实测结果

智能驾驶、精密农业和无人机等新兴行业要求全球导航卫星系统(GNSS)提供更加快速、准确的导航定位服务。非差非组合PPP-RTK融合了精密单点定位(PPP)和实时动态定位(RTK)两者的优势,能灵活处理多频多模数据并实现区域广覆盖的快速高精度定位。然而,PPP-RTK仍处于技术研发阶段,产业化应用尚未完全成型。本文从理论到实践,构建了码分多址和频分多址非差非组合PPP-RTK模型,开发了相应的实时解算软件,并研制了一款终端样机。基于平均站间距为154 km的京津冀参考网估计的精密改正产品,将终端样机分别搭载在无人机、农机和跑车上,开展了实时动态定位试验。试验结果表明,PPP-RTK终端样机在3个场景下的模糊度首次固定时间分别为5、2和7 s,模糊度固定成功率分别为99.79%、99.14%和98.96%,水平和高程定位精度分别在1 cm和4 cm左右。试验结果证明了自研PPP-RTK终端样机能提供连续、可靠、高精度的定位服务。

理性认识蓝光危害及蓝光生物安全性评价

日常生活和工作中会接触到多种多样的蓝光辐射,蓝光的生物作用及其生物安全性也越来越受到关注。国内外已颁布一系列关于蓝光潜在健康危害、蓝光生物安全性评价,以及蓝光产品风险组别的指南、技术报告和标准。“蓝光危害”是灯和灯系统的光生物安全性评价标准体系中使用的一个专业技术术语。该术语并非泛指蓝光辐射有风险,也不应被误认为蓝光都是有害的。蓝光在维持正常视觉和人体健康中发挥着重要作用,理性认识蓝光危害对蓝光技术的发展和应用有积极意义。本文围绕蓝光辐射的一些重要性质、来源、蓝光的生物作用以及蓝光生物安全性评价体系,对蓝光危害目前的共识以及误解进行了客观和理性分析,并对关于蓝光辐射的生物安全性的相关标准以及蓝光生物安全性评价方法进行了综述。

Orthotopic liver transplantation from a donor with Schistosoma japonicum

To the Editor：Despite of the rapid increase of donation after cardiac death （DCD） in China, the shortage of organs continues to be a major problem. Every organ procured is so valuable that it should never be discarded easily, especially a liver that could save a patient＇s life in an emergency. This leads to the use of grafts from donors with unrecognized Here and unusual diseases, including schistosomiasis. we reported a case of orthotopic liver transplantation （OLT） from a donor with Schistosorna japonicurn to a patient with end-stage cirrhosis due to HBV infection.

100 Hertz frame-rate switching threedimensional orbital angular momentum multiplexing holography via cross convolution

The orbital angular momentum(OAM)of light has been implemented as an information carrier in OAM holography.Holographic information can be multiplexed in theoretical unbounded OAM channels,promoting the applications of optically addressable dynamic display and high-security optical encryption.However,the frame-rate of the dynamic extraction of the information reconstruction process in OAM holography is physically determined by the switching speed of the incident OAM states,which is currently below 30 Hz limited by refreshing rate of the phase-modulation spatial light modulator(SLM).Here,based on a cross convolution with the spatial frequency of the OAM-multiplexing hologram,the spatial frequencies of an elaborately-designed amplitude distribution,namely amplitude decoding key,has been adopted for the extraction of three-dimensional holographic information encoded in a specific OAM information channel.We experimentally demonstrated a dynamic extraction frame rate of 100 Hz from an OAM multiplexing hologram with 10 information channels indicated by individual OAM values from-50 to 50.The new concept of cross convolution theorem can even provide the potential of parallel reproduction and distribution of information encoded in many OAM channels at various positions which boosts the capacity of information processing far beyond the traditional decoding methods.Thus,our results provide a holographic paradigm for high-speed 3D information processing,paving an unprecedented way to achieve the high-capacity short-range optical communication system.

Effects of tree diversity on insect herbivory

Tree diversity has long been considered a key driver of insect herbivory in forest ecosystems.However,studies have given contradictory results:increased tree diversity can have positive,negative or neutral effects on insect herbivory.Since many issues can complicate the tree-herbivore interactions,the descriptor‘tree diversity’per se actually has only limited explanatory power for insect herbivory.Particularly,in addition to the direct bottom-up effects on insect herbivores,tree diversity may have stronger indirect top-down effects via natural enemies of insect herbivores.However,most research has addressed only direct bottom-up impacts.In fact,insect herbivory is the result of complex interactions(food webs)among all the species in a community.Although it is hard to integrate all functionally important species and dynamic information into food webs,the effects of tree diversity on insect herbivory are highly dependent on the dominant species at different trophic levels.It is important and practical to simultaneously consider the characteristics of main trees,herbivores,and natural enemies when attempting to predict the overall effects of forest tree diversity on insect herbivory.In order to ensure comparability between studies,it is necessary to classify them according to the descriptors of insect herbivory and tree diversity,and to compare results within each category.These measures might enhance our understanding of the mechanisms by which tree diversity drives insect herbivory and,in turn,help to develop sustainable pest management strategies for forests.

Asymmetrical spiral spectra and orbital angular momentum density of non-uniformly polarized vortex beams in uniaxial crystals

To explore the effect of non-uniform polarization on orbital angular momentum(OAM) in anisotropic medium, in this work investigated are the evolution of the spiral spectra and OAM densities of non-uniformly polarized vortex(NUPV)beams in uniaxial crystals propagating orthogonal to the optical axis, and also the case of uniformly polarized vortex(UPV)beams with left-handed elliptical polarization. In the input plane, the NUPV beams present their spiral spectra of m-mode concentrated at m = l ± 1 modes rather than m = l mode, and reveal the relation among topological charge l, mode of spiral spectra m and the power weight value Rmexpressed by l=∑^(∞)_(m)=-∞Rm. is still satisfied for UPV beams in uniaxially anisotropic crystals, whereas for NUPV beams their relations are no longer valid owing to non-uniform polarization. Furthermore, the analysis indicates that the asymmetrical distribution of power weight of spiral spectra and the non-zero value in the sum of longitudinal OAM densities originate from the initial non-uniform polarization and anisotropy in uniaxial crystals rather than topological charges. In addition, the relation between spiral spectrum and longitudinal OAM density is numerically discussed. This work may provide an avenue for OAM-based communications,optical metrology, and imaging by varying the initial non-uniform polarization.

Heterobifunctional PEG-grafted black phosphorus quantum dots: “Three-in-One”nano-platforms for mitochondria-targeted photothermal cancer therapy

Black phosphorus(BP)nano-materials,especially BP quantum dots(BPQDs),performs outstanding photothermal antitumor effects,excellent biocompatibility and biodegradability.However,there are several challenges to overcome before offering real benefits,such as poor stability,poor dispersibility as well as difficulty in tailoring other functions.Here,a“three-in-one”mitochondria-targeted BP nano-platform,called as BPQD-PEG-TPP,was designed.In this nano-platform,BPQDs were covalently grafted with a heterobifunctional PEG,in which one end was an aryl diazo group capable of reacting with BPQDs to form a covalent bond and the other end was a mitochondria-targeted triphenylphosphine(TPP)group.In addition to its excellent near-infrared photothermal properties,BPQD-PEG-TPP had much enhanced stability and dispersibility under physiological conditions,efficient mitochondria targeting and promoted ROS production through a photothermal effect.Both in vitro and in vivo experiments demonstrated that BPQD-PEG-TPP performed much superior photothermal cytotoxicity than BPQDs and BPQD-PEG as the mitochondria targeted PTT.Thus this“three-in-one”nanoplatform fabricated through polymer grafting,with excellent stability,dispersibility and negligible side effects,might be a promising strategy for mitochondria-targeted photothermal cancer therapy.

Intruder trajectory tracking in a three-dimensional vibration-driven granular system:Unveiling the mechanism of the Brazil nut effect

We employ a Hall-effect magnetic sensor array to accurately track the trajectory of a single magnetic sphere,referred to as the“intruder,”within a three-dimensional vibro-fluidized granular bed to unravel the underlying physical mechanism governing the motion of the intruder.Within the acceleration range of 3.5 g≥Γ≥1.5 g,we find that,regardless of the intruder's initial position,it consistently reaches the same equilibrium depth when the vibration acceleration(Γ)and frequency(ω)are fixed.ForΓ≤2.5 g,the equilibrium position lies on the surface of the granular bed,while forΓ>2.5 g,it shifts below the surface.Additionally,intruders with different densities exhibit varying equilibrium depths,with higher density resulting in a deeper equilibrium position.To understand the mechanism behind the intruder's upward or downward motion,we measure its rising or sinking velocities under different vibration parameters.Our findings demonstrate that the rising velocity of the intruder,under varying vibration accelerations(Γ)and frequencies(ω),can be collapsed using the ratioΓ/ω,while the sinking velocity remains unaffected by the vibration strength.This confirms that the upward motion of the larger sphere,associated with the Brazil nut effect,primarily arises from the void-filling mechanism of the bed particles.Furthermore,our experiments reveal that the presence of convection within the bed particles has minimal impact on the motion of the intruder.

A Review on Strengthening of Timber Beams Using Fiber Reinforced Polymers

Fiber reinforced polymer(FRP)has been used in the construction industry because of its advantages such as high strength,light weight,corrosion resistance,low density and high elasticity.This paper presents a review of bonding techniques adopted to strengthen timber beams using FRP to achieve larger spans.Different methods of bonding between FRP and timber beams have been summarized with a focus on the influencing factors and their effects as well as relevant bond-slip models proposed for fundamental understanding.Experimental investigations to evaluate the flexural performance of timber beams strengthened by FRP bars,sheets and wraps have also been critically reviewed to identify key influencing parameters.Limited research available on the shear performance of FRP reinforced timber beams have been analyzed to determine the influencing factors of the shear performance in timber-FRP beams.The paper finally presents an overall summary of the current-state-of-the-art and proposes some future research directions in the field.

Detecting chimerism contributes to diagnosis of graft versus host disease after orthotopic liver transplantation

To the Editor:Graft versus host disease(GVHD)occurs when the immunocompetent cells from the donor mount an immune response against the tissues of the host[1].It is commonly seen in the patients who received hematopoietic stem cell transplantation(HSCT).GVHD is a rare but lethal complication in orthotopic liver

煤化工工艺与设备的关键技术

煤炭资源,在国家社会经济发展中的贡献较大。然而,煤炭资源产业对自然生态环境产生的破坏与污染现象越愈明显。近些年来,虽然国内煤炭资源的利用率得到很大程度的降低,然而国内“贫油富煤”的资源格局仍尚未得到根本性的改变,煤炭资源仍是保障国家能源安全的重要基础。因此,以煤化工技术发展现状为切入点,分析煤化工工艺关键技术要点与煤化工设备关键技术要点,并结合现代煤化工相关技术问题,提出有效的优化对策,以保证我国煤化工产业的可持续发展。