Multiple pulp stones emerge across all teeth during mixed dentition:A case report

BACKGROUND This paper reports a rare presentation of multiple pulp stones(PSs)emerging in all teeth during mixed dentition.It offers valuable insights into the clinical diagnosis,treatment,and prognosis of multiple PSs,shedding light on their occurrence during the mixed dentition period.CASE SUMMARY A 10-year-old girl presented with repeated pain in the mandibular right posterior teeth.Intraoral examination revealed carious lesions,abnormal tooth shapes,and anomalies in tooth number.Radiographic examinations showed multiple PSs with diverse shapes,sizes,and quantities in all teeth,alongside anomalies in tooth shape and number.Root canal therapy was initiated,but the patient initially lacked timely follow-up.Upon return for treatment completion,an extracted tooth revealed irregular calculus within the pulp cavity.CONCLUSION This case underscores the importance of considering multiple PSs in mixed dentition,necessitating comprehensive evaluation and management strategies.

Selective hydrogenation of glucose to sorbitol with tannic acid-based porous carbon sphere supported Ni-Ru bimetallic catalysts

Ni-Ru bimetallic porous carbon sphere(Ni-Ru@PCS) catalysts were synthesized via formaldehyde-assisted, metal-coordinated crosslinking sol-gel chemistry, in which biomass-derived tannic acid and F127 surfactant were used as carbon precursor and soft template, respectively, and Ni2+and Ru3+were used as cross-linkers. In the developed method, Ni-Ru particles became uniformly dispersed in the carbon skeleton due to strong coordination bonds between metal ions(Ni2+and Ru^(3+)) and tannic acid molecules and bimetal interactions. The as-synthesized Ni-Ru10:1@PCS catalyst with a loading Ni:Ru mole ratio of 10:1 was applied for the selective hydrogenation of glucose to sorbitol, and provided 99% glucose conversion with a sorbitol selectivity of 100% at 140℃ in 150 min reaction time and exhibited good stability and recyclability in which sorbitol yield remained at 98% after 4 cycles with little or no metal agglomeration. The catalyst was applied to glucose solutions as high as 20 wt% with 97% sorbitol yields being obtained at 140℃ in 20 h. The developed bimetallic porous carbon sphere catalysts take advantage of sustainably-derived materials in their structure and are applicable to related biomass conversion reactions.

Coupled Ferroelectricity and Correlated States in a Twisted Quadrilayer MoS_(2) Moiré Superlattice

Moiré superlattices have emerged as a highly controllable quantum platform for exploration of various fascinating phenomena,such as Mott insulator states,ferroelectric order,unconventional superconductivity and orbital ferromagnetism.Although remarkable progress has been achieved,current research in moiré physics has mainly focused on the single species properties,while the coupling between distinct moiré quantum phenomena remains elusive.Here we demonstrate,for the first time,the strong coupling between ferroelectricity and correlated states in a twisted quadrilayer MoS2moiré superlattice,where the twist angles are controlled in sequence to be ~57°,~0°,and ~-57°.Correlated insulator states are unambiguously established at moiré band filling factors v = 1,2,3 of twisted quadrilayer MoS_(2).Remarkably,ferroelectric order can occur at correlated insulator states and disappears quickly as the moiré band filling deviates from the integer fillings,providing smoking gun evidences of the coupling between ferroelectricity and correlated states.Our results demonstrate the coupling between different moiré quantum properties and will hold great promise for new moiré physics and applications.

Vulnerability assessment of UAV engine to laser based on improved shotline method

Laser anti-drone technology is entering the sequence of actual combat,and it is necessary to consider the vulnerability of typical functional parts of UAVs.Since the concept of"vulnerability"was proposed,a variety of analysis programs for battlefield targets to traditional weapons have been developed,but a comprehensive assessment methodology for targets'vulnerability to laser is still missing.Based on the shotline method,this paper proposes a method that equates laser beam to shotline array,an efficient vulnerability analysis program of target to laser is established by this method,and the program includes the circuit board and the wire into the vulnerability analysis category,which improves the precision of the vulnerability analysis.Taking the UAV engine part as the target of vulnerability analysis,combine with the"life-death unit method"to calculate the laser penetration rate of various materials of the UAV,and the influence of laser weapon system parameters and striking orientation on the killing probability is quantified after introducing the penetration rate into the vulnerability analysis program.The quantitative analysis method proposed in this paper has certain general expansibility,which can provide a fresh idea for the vulnerability analysis of other targets to laser.

Broad temperature adaptability of vanadium redox flow battery-part4:Unraveling wide temperature promotion mechanism of bismuth for V^(2+)/V^(3+) couple

Vanadium flow battery （VFB） is a fast going and promising system for large-scale stationary energy stor- age. However, drawbacks such as low power density and narrow temperature window caused by poor catalytic activity of graphite felt （GF） electrodes limit its worldwide application. In this paper, bismuth, as a low-cost, no-toxic and high-activity electrocatalyst, is used to modify the thermal activated GF （TGF） via a facile hydrothermal method. Bismuth can effectively inhibit the side reaction of hydrogen evolution in wide temperature range, while promoting the V2＋/V3＋ redox reaction. As a result, the VFB assembled with Bi/TGF as negative electrode demonstrates outstanding rate performance under the current density up to 400 mAcm-2, as well as a long-term stability over 600 charging/discharging cycles at a high cur- rent density of 150mA cm-2. Moreover, it also shows excellent temperature adaptability from -10 ℃ to 50 ℃ and high durability for life test at the temperature of 50 ℃.

ZIF-derived holey electrode with enhanced mass transfer and N-rich catalytic sites for high-power and long-life vanadium flow batteries

Electrode materials with good redox kinetics,excellent mass transfer characteristics and ultra-high stability play a crucial role in reducing the life-cycle cost and prolonging the maintenance-free time of the vanadium flow batteries(VFB).Herein,a nitrogen-doped porous graphite felt electrode(N-PGF)is proposed by growing ZIF-67 nanoparticles on carbon fibers and then calcinating and acid etching.The multi-scale structure of“carbon fiber gap(electrolyte flow),micro/nano pore(active species diffusion)and Nitrogen active center(reaction site)”in N-PGF electrode effectively increases the catalytic sites and promotes mass transfer characteristics.Reasonable electrode design makes the battery show excellent rate performance and ultra-high cycling stability.The peak power density of the battery reaches 1006 mW cm^(-2).During 1000 cycles at 150 mA cm^(-2),the average discharge capacity and average discharge energy of N-PGF increase substantially by 11.6%and 23.4%compared with the benchmark thermal activated graphite felt,respectively.More excitingly,after ultra-long term(5000 cycles)operation at an ultra-high current density(300 mA cm^(-2)),N-PGF exhibits an unprecedented energy efficiency retention(99.79%)and electrochemical performance stability.

Emergence of Chern Insulating States in Non-Magic Angle Twisted Bilayer Graphene

Twisting two layers into a magic angle(MA) of ~1.1°is found essential to create low energy flat bands and the resulting correlated insulating,superconducting,and magnetic phases in twisted bilayer graphene(TBG).While most of previous works focus on revealing these emergent states in MA-TBG,a study of the twist angle dependence,which helps to map an evolution of these phases,is yet less explored.Here,we report a magnetotransport study on one non-magic angle TBG device,whose twist angle θ changes from 1.25° at one end to 1.43°at the other.For θ=1.25° we observe an emergence of topological insulating states at hole side with a sequence of Chern number |C|=4-|v|,where v is the number of electrons(holes) in moire unite cell.When θ> 1.25°,the Chern insulator from flat band disappears and evolves into fractal Hofstadter butterfly quantum Hall insulator where magnetic flux in one moire unite cell matters.Our observations will stimulate further theoretical and experimental investigations on the relationship between electron interactions and non-trivial band topology.

TTA as a potential hole transport layer for application in conventional polymer solar cells

Hole transport layers(HTLs)play a vital role in organic solar cells(OSCs).In this work,a derivative of tetrathiafulvalene with four carboxyl groups TTA was introduced as a novel HTL to fabricate OSC with high performance.Displaying a better energy level match between HTL and active layers,the TTA based devices show a peak power conversion efficiency of 9.09%,which is comparable to the devices based on PEDOT:PSS.The favorable surface morphology recorded via atomic force microscopy,low series loss and charge recombination indicated by electrochemical impedance spectroscopy,synchronously verify the potential of TTA for application in OSCs as a valid kind of HTLs.

Iterative dipole moment method for calculating dielectrophoretic forces of particle-particle electric field interactions

Dielectrophoresis （DEP） is one of the most popular techniques for bio-particle manipulation in microfluidic systems. Traditional calculation of dielectrophoretic forces of single particle based on the approximation of equivalent dipole moment （EDM） cannot be directly applied on the dense particle interactions in an electrical field. The Maxwell stress tensor （MST） method is strictly accurate in the theory for dielectrophoretic forces of particle interaction, but the cumbersome and complicated numerical computation greatly limits its practical applications. A novel iterative dipole moment （IDM） method is pre- sented in this work for calculating the dielectrophoretic forces of particle-particle inter- actions. The accuracy, convergence, and simplicity of the IDM are confirmed by a series of examples of two-particle interaction in a DC/AC electrical field. The results indicate that the IDM is able to calculate the DEP particle interaction forces in good agreement with the MST method. The IDM is a purely analytical operation and does not require complicated numerical computation for solving the differential equations of an electrical field while the particle is moving.

Improved interfacial property by small molecule ethanediamine for high performance inverted planar perovskite solar cells

We report a simple and effective method to realize desirable interfacial property for inverted planar perovskite solar cells(PSCs)by using small molecule ethanediamine for the construction of a novel polyelectrolyte hole transport material(P3CT-ED HTM).It is found that P3CT-ED can not only improve the hole transport property of P3CT-K but also improve the crystallinity of adjacent perovskite film.In addition,the introduction of ethanediamine into P3CT realigns the conduction and valence bands upwards,passivates surface defects and reduces nonradiative recombination.As a consequence,compared to P3CT-K hole transport layer(HTL)based devices,the average power conversion efficiency(PCE)is boosted from17.2% to 19.6% for the counterparts with P3CT-ED,with simultaneous enhancement in open circuit voltage and fill factor.The resultant device displays a champion PCE of 20.5% with negligible hysteresis.

Observation of quadratic magnetoresistance in twisted double bilayer graphene

Magnetoresistance(MR) provides rich information about Fermi surface, carrier scatterings, and exotic phases for a given electronic system. Here, we report a study of the magnetoresistance for the metallic states in twisted double bilayer graphene(TDBG). We observe quadratic magnetoresistance in both Moiré valence band(VB) and Moiré conduction band(CB). The scaling analysis shows validity of Kohler's rule in the Moiré valence band. On the other hand, the quadratic magnetoresistance appears near the halo structure in the Moiré conduction band, and it violates Kohler's rule, demonstrating the MR scaling related to band structure in TDBG. We also propose an alternative scaling near the halo structure. Further analysis implies that the observed quadratic magnetoresistance and alternative scaling in conduction band are related to the halo boundary. Our results may inspire investigation on MR in twisted 2D materials and provide new knowledge for MR study in condensed matter physics.

A BIOSENSOR USING COUPLED PLASMON WAVEGUIDE RESONANCE COMBINED WITH HYPERSPECTRAL FLUORESCENCE ANALYSIS

We developed a biosensor that is capable for simultaneous surface plasmon resonance(SPR)sensing and hyperspectral fuores cence analysis in this paper.A symmetrical metal-dielectric slabscheme is employed for the excitation of coupled plasnon waveguide resonance(CPWR)in thepresent work.Resonance bet ween surface plasmon mode and the guided waveguide mode gen-erates narrower full width half-maximum of the refective curves which leads to increased pre.cision for the determination of refractive index over conventional SPR sensors.In addition,CPWR also fers longer surface propagation depths and higher surface electric field strengthsthat enable the excitation of fluorescence with hyperspectral technique to maintain an appreci-able signal-to-noise ratio.The refractive index information obtained from SPR sensing and thechemical properties obt ained through hyperspectral fluorescence analysis confirm each other toexclude false-positive or false-negative cases.The sensor provides a comprehensive understandingof the biological events on the sensor chips.

Evaluation method for assessing the auxiliary service transaction mechanism in regional power markets

Accurate and seamless auxiliary services in the power market can guarantee smooth and continuous power system operation. China’s new round of power system reform has entered a critical period, and reform implementation requires comprehensive improvements in the maturity of the supporting auxiliary service market. This study reviews the development status and evolution path of the European unified power market and the US regional power market, provides experience for the development of China’s regional power market, then identifies the key influencing factors of auxiliary service trading mechanism design in regional power markets. To analyze the rationality of the auxiliary service trading evaluation index, this paper established an evaluation model for assessing regional power markets. Using combined weight optimization, the gray correlation TOPSIS method was applied to comprehensively evaluate auxiliary service trading in the regional power market. Finally, the application of the proposed evaluation method was briefly analyzed to examine four regional power markets in China and evaluate the effectiveness of current market construction in different regions and provide suggestions for future market construction.

Epitaxial growth of trilayer graphene moiré superlattice

The graphene-based moiré superlattice has been demonstrated as an exciting system for investigating strong correlation phenomenon. However, the fabrication of such moiré superlattice mainly relies on transfer technology. Here, we report the epitaxial growth of trilayer graphene(TLG) moiré superlattice on hexagonal boron nitride(h BN) by a remote plasma-enhanced chemical vapor deposition method. The as-grown TLG/h BN shows a uniform moiré pattern with a period of ~ 15 nm by atomic force microscopy(AFM) imaging, which agrees with the lattice mismatch between graphene and h BN. By fabricating the device with both top and bottom gates, we observed a gate-tunable bandgap at charge neutral point(CNP) and displacement field tunable satellite resistance peaks at half and full fillings. The resistance peak at half-filling indicates a strong electron–electron correlation in our grown TLG/h BN superlattice. In addition, we observed quantum Hall states at Landau level filling factors ν = 6, 10, 14,..., indicating that our grown trilayer graphene has the ABC stacking order. Our work suggests that epitaxy provides an easy way to fabricate stable and reproducible two-dimensional strongly correlated electronic materials.

Lone pair-π interaction induced regioselective sulfonation of ethers under light irradiation

Non-covalent interactions are of significance in supramolecular chemistry and biochemistry,while synthetic procedures driven by these weak interactions remain challenging and rare.Inspired by the lone pair-π interaction presence in the Z-DNA structure,a light-induced regioselective sulfonation of ethers taking advantage of the lone pair-π interaction between the oxygen of ethers and sulfonyl chlorides has been disclosed.Moreover,this strategy is also applicable to the sulfonation of aniline derivatives.Features of the methods include readily accessible starting materials,high atom-economy,green and photocatalyst-free conditions and broad functional group tolerance.Mechanism studies suggest that the lone pair-πinteraction plays an important role to initiate the transformation.

A saccharides sensor developed by symmetrical optical waveguide-based surface plasmon resonance

We proposed a new saccharides sensor developed by symmetrical optical waveguide(SOW)-based surface plasmon resonance(SPR).This unique MgF_(2)/Au/MgF_(2)/Analyte film structure results in longer suface plasmon wave(SPW)propagation lengths and depths,leading to an increment of resolution.In this paper,we managed to decorate the dielectric interface(MgF_(2) layer)by depositing a thin polydopamine film as surface adherent that provides a platform for secondary reactions with the probe molecule.3-Aminophenylboronic acid(3-PBA)is chosen to be the saccharides sense probe molecule in the present work.The aqueous huumnor of Diabetes and Cataract patient whose blood glucose level is normal are analyzed and the results dermonstrated that this sensor shows great potential in monitoring the blood siugar and can be adapted in the field of biological monitoring in the future.

A review of experimental advances in twisted graphene moiré superlattice

Twisted moirésuperlattice receives tremendous interests since the discovery of correlated insulating states and superconductivity in magic angle twist bilayer graphene(MA-TBG)[Nature 55680(2018),Nature 55643(2018)],even gives arise to a new field"twistronics"[Science 361690(2018)].It is a new platform hosting strong electron correlations,providing an alternative for understanding unconventional superconductivity.In this article,we provide a review of recent experimental advances in the twisted moirésuperlattice,from MA-TBG to twisted double bilayer graphene and other two-dimensional materials based moirésuperlattice,covering correlated insulating states,superconductivity,magnetism,et al.

Cooperative Detection Method for DDoS Attacks Based on Blockchain

Distributed Denial of Service(DDoS)attacks is always one of the major problems for service providers.Using blockchain to detect DDoS attacks is one of the current popular methods.However,the problems of high time overhead and cost exist in the most of the blockchain methods for detecting DDoS attacks.This paper proposes a blockchain-based collaborative detection method for DDoS attacks.First,the trained DDoS attack detection model is encrypted by the Intel Software Guard Extensions(SGX),which provides high security for uploading the DDoS attack detection model to the blockchain.Secondly,the service provider uploads the encrypted model to Inter Planetary File System(IPFS)and then a corresponding Content-ID(CID)is generated by IPFS which greatly saves the cost of uploading encrypted models to the blockchain.In addition,due to the small amount of model data,the time cost of uploading the DDoS attack detection model is greatly reduced.Finally,through the blockchain and smart contracts,the CID is distributed to other service providers,who can use the CID to download the corresponding DDoS attack detection model from IPFS.Blockchain provides a decentralized,trusted and tamper-proof environment for service providers.Besides,smart contracts and IPFS greatly improve the distribution efficiency of the model,while the distribution of CID greatly improves the efficiency of the transmission on the blockchain.In this way,the purpose of collaborative detection can be achieved,and the time cost of transmission on blockchain and IPFS can be considerably saved.We designed a blockchain-based DDoS attack collaborative detection framework to improve the data transmission efficiency on the blockchain,and use IPFS to greatly reduce the cost of the distribution model.In the experiment,compared with most blockchain-based method for DDoS attack detection,the proposed model using blockchain distribution shows the advantages of low cost and latency.The remote authentication mechanism of Intel SGX provides high security and integrity,and ensures the availability of distributed models.

Real- and momentum-indirect neutral and charged excitons in a multi-valley semiconductor

Excitons dominate the photonic and optoelectronic properties of a material.Although significant advancements exist in understanding various types of excitons,progress on excitons that are indirect in both real-and momentum-spaces is still limited.Here,we demonstrate the real-and momentum-indirect neutral and charged excitons(including their phonon replicas)in a multi-valley semiconductor of bilayer MoS_(2),by performing electric-field/doping-density dependent photoluminescence.Together with first-principles calculations,we uncover that the observed real-and momentum-indirect exciton involves electron/hole from K/Γvalley,solving the longstanding controversy of its momentum origin.Remarkably,the binding energy of real-and momentum-indirect charged exciton is extremely large(i.e.,~59 meV),more than twice that of real-and momentum-direct charged exciton(i.e.,~24 meV).The giant binding energy,along with the electrical tunability and long lifetime,endows real-and momentum-indirect excitons an emerging platform to study many-body physics and to illuminate developments in photonics and optoelectronics.

国产低Mo耐火钢高大空间建筑雨棚结构抗火设计

火灾是钢结构安全的主要威胁之一,传统钢结构的主要防火措施为涂抹防火涂料、浇筑混凝土形成组合结构或设置防火板,其中又以防火涂料应用最为广泛。然而,室外涂抹防火涂料耐久性差,存在坠落伤人隐患。且对于防火要求较高的钢结构需厚涂防火涂料,这尤其会影响地标性建筑的建筑效果。近年来,耐火钢作为一种新型的防火保护措施逐渐兴起,其能够有效避免上述防火措施的缺点,但由于大量添加合金元素Mo导致其成本往往较高。南钢集团研发的新型低Mo耐火钢在保证优异抗火性能的同时减少了Mo元素的添加量,从而减小了综合制造成本而受到广泛关注。基于构件承载力法,依托于某具有高大空间的钢结构大雨棚,对南钢新型低Mo耐火钢在抗火设计中的应用可行性进行了研究。作为某市新建地标性建筑,设计要求大雨棚屋面梁应满足3 h耐火极限。首先探索了高温下该国产耐火钢的材性折减规律,通过与现行规范理论计算结果对比,发现该国产耐火钢满足通用耐火钢的材性折减要求且可根据规范相应公式准确预测不同温度下的材性折减。随后基于结构抗火设计原则共确定了11个火灾场景,分别分布于雨棚边跨及中跨。以上火灾场景被认为已覆盖该大雨棚实际使用状态下可能发生的所有火灾。进一步根据相关规范,分析了各火灾场景下大雨棚的升温规律。分析表明,按照设计要求经3 h升温后,边跨火灾场景下最高空气温度接近750℃,最高构件温度接近730℃;中跨火灾场景下最高空气温度接近600℃,最高构件温度接近570℃,均远低于ISO 834标准火灾升温。高大空间建筑火灾下升温低的特点表明高大空间建筑可作为未来耐火钢应用的主要场景。最终,分别采用Q355普通结构钢与Q345FR国产耐火钢对各火灾工况下各构件进行承载力和稳定性验算。结果表明,若仅采用Q355普通结构钢,高温下钢梁GL3、GL3a及GL4无法满足承载力要求;而若采用Q345FR耐火钢,屋顶钢构件的强度和整体稳定性均能满足要求。