Research on simultaneous localization and mapping for AUV by an improved method:Variance reduction FastSLAM with simulated annealing

At present,simultaneous localization and mapping(SLAM) for an autonomous underwater vehicle(AUV)is a research hotspot.Aiming at the problem of non-linear model and non-Gaussian noise in AUV motion,an improved method of variance reduction fast simultaneous localization and mapping(FastSLAM) with simulated annealing is proposed to solve the problems of particle degradation,particle depletion and particle loss in traditional FastSLAM,which lead to the reduction of AUV location estimation accuracy.The adaptive exponential fading factor is generated by the anneal function of simulated annealing algorithm to improve the effective particle number and replace resampling.By increasing the weight of small particles and decreasing the weight of large particles,the variance of particle weight can be reduced,the number of effective particles can be increased,and the accuracy of AUV location and feature location estimation can be improved to some extent by retaining more information carried by particles.The experimental results based on trial data show that the proposed simulated annealing variance reduction FastSLAM method avoids particle degradation,maintains the diversity of particles,weakened the degeneracy and improves the accuracy and stability of AUV navigation and localization system.

Function and clinical significance of SUMOylation in type Ⅰ endometrial carcinoma

Objective This study elucidated the function and role of SUMOylation in type Ⅰ endometrial carcinoma.Methods Fifty type Ⅰ endometrial carcinoma cases and para-cancer tissue samples were collected.The expression levels of ubiquitin-conjugating enzyme E2I(Ube2 i,Ubc9) and small ubiquitin-like modifier 1(SUMO1)/sentrin-specific peptidase 1(SENP1) proteins were examined using immunohistochemistry and the correlation with clinicopathological parameters was analyzed.Results Ubc9 expression in type Ⅰ endometrial carcinoma tissues was significantly higher than that in the para-cancer tissues;in contrast,the expression of the SENP1 protein was markedly lower than that in the para-cancer tissues.Ubc9 and SENP1 expression levels were negatively correlated and were associated with tumor differentiation,but not age,depth of invasion,tumor stage,and lymph node metastasis.Conclusion SUMOylation modification plays a major role in the pathogenesis and development of type Ⅰ endometrial carcinoma.Thus,it could be a potential target for the treatment of endometrial cancer.

Observation of maximal intrinsic chirality empowered by dual quasi-bound states in the continuum in a planar metasurface

Metasurfaces with spin-selective transmission play an increasingly critical role in realizing optical chiral responses,especially for strong intrinsic chirality,which is limited to complex three-dimensional geometry.In this paper,we propose a planar metasurface capable of generating maximal intrinsic chirality and achieving dual-band spinselective transmission utilizing dual quasi-bound states in the continuum(quasi-BICs)caused by the structural symmetry breaking.Interestingly,the value of circular dichroism(CD)and the transmittance of two kinds of circular polarization states can be arbitrarily controlled by tuning the asymmetry parameter.Remarkable CD approaching unity with the maximum transmittance up to 0.95 is experimentally achieved in the dual band.Furthermore,assisted by chiral BICs,the application in polarization multiplexed near-field image display is also exhibited.Our work provides a new avenue to flexibly control intrinsic chirality in planar structure and offers an alternative strategy to develop chiral sensing,multiband spin-selective transmission,and high-performance circularly polarized wave detection.The basic principle and design method of our experiments in the microwave regime can be extended to other bands,such as the terahertz and infrared wavelengths.

Efficient and stable wireless power transfer based on the non-Hermitian physics

As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.

High-energy-density plasma in femtosecond-laser-irradiated nanowire-array targets for nuclear reactions

In this work,the high-energy-density plasmas(HEDP)evolved from joule-class-femtosecond-laser-irradiated nanowire-array(NWA)targets were numerically and experimentally studied.The results of particle-in-cell simulations indicate that ions accelerated in the sheath field around the surfaces of the nanowires are eventually confined in a plasma,contributing most to the high energy densities.The protons emitted from the front surfaces of the NWA targets provide rich information about the interactions that occur.We give the electron and ion energy densities for broad target parameter ranges.The ion energy densities from NWA targets were found to be an order of magnitude higher than those from planar targets,and the volume of the HEDP was several-fold greater.At optimal target parameters,8%of the laser energy can be converted to confined protons,and this results in ion energy densities at the GJ/cm^(3) level.In the experiments,the measured energy of the emitted protons reached 4 MeV,and the changes in energy with the NWA’s parameters were found to fit the simulation results well.Experimental measurements of neutrons from 2H(d,n)3He fusion with a yield of(24±18)×10^(6)/J from deuterated polyethylene NWA targets also confirmed these results.

老反应、新认识:不容小觑的乙硼烷与氨的反应

看似简单实际却很复杂的乙硼烷(B_(2)H_(6),diborane)与氨(NH_(3))的反应已经困扰了硼化学家数十年。该反应在不同实验条件下可生成硼氢化二氢二氨合硼(III)([NH_(3)BH_(2)NH_(3)]BH_(4),diammoniate of diborane,DADB),氨硼烷(NH_(3)·BH_(3),ammonia borane,AB),氨基乙硼烷(NH_(2)B_(2)H_(5),aminodiborane,ADB)等化合物。从1923年起,化学家们对影响乙硼烷与路易斯碱反应的因素,如立体效应、诱导效应、溶剂效应、介电常数等进行研究,但一直无法根据上述影响因素准确预测产物。基于乙硼烷在THF中以THF·BH_(3)存在、路易斯碱与乙硼烷或THF·BH_(3)反应产物相同等实验事实,化学家们巧妙利用NH_(3)与THF·BH_(3)的反应,在温和的条件下研究了DADB、AB的生成机理,发现双氢键是控制反应的重要因素。利用AB与THF·BH_(3)的反应,实验和理论计算结果进一步揭示了基于双氢键的ADB的复杂形成机理。

Perfect light absorber with a PT phase transition via coupled topological interface states

Recently,the concepts of parity–time(PT)symmetry and band topology have inspired many novel ideas for light manipulation in their respective directions.Here we propose and demonstrate a perfect light absorber with a PT phase transition via coupled topological interface states(TISs),which combines the two concepts in a onedimensional photonic crystal heterostructure.By fine tuning the coupling between TISs,the PT phase transition is revealed by the evolution of absorption spectra in both ideal and non-ideal PT symmetry cases.Especially,in the ideal case,a perfect light absorber at an exceptional point with unidirectional invisibility is numerically obtained.In the non-ideal case,a perfect light absorber in a broken phase is experimentally realized,which verifies the possibility of tailoring non-Hermiticity by engineering the coupling.Our work paves the way for novel effects and functional devices from the exceptional point of coupled TISs,such as a unidirectional light absorber and exceptional-point sensor.

Observation of accurately designed bound states in the continuum in momentum space

Bound states in the continuum(BICs)in artificial photonic structures have received considerable attention since they offer unique methods for the extreme field localization and enhancement of light-matter interactions.Usually,the symmetry-protected BICs are located at high symmetric points,while the positions of accidental BICs achieved by tuning the parameters will appear at some points in momentum space.Up to now,to accurately design the position of the accidental BIC in momentum space is still a challenge.Here,we theoretically and experimentally demonstrate an accurately designed accidental BIC in a two-coupled-oscillator system consisting of bilayer gratings,where the optical response of each grating can be described by a single resonator model.By changing the interlayer distance between the gratings to tune the propagation phase shift related to wave vectors,the position of the accidental BIC can be arbitrarily controlled in momentum space.Moreover,we present a general method and rigorous numerical analyses for extracting the polarization vector fields to observe the topological properties of BICs from the polarization-resolved transmission spectra.Finally,an application of the highly efficient second harmonic generation assisted by quasi-BIC is demonstrated.Our work provides a straightforward strategy for manipulating BICs and studying their topological properties in momentum space.

钼酸铋在光催化技术中的改性与应用

目前,生态污染和能源短缺成为威胁人类生存的全球性问题,绿色、低碳的光催化技术对解决环境及能源问题具有战略性意义。作为三元奥里维里斯型(Aurivillius)化合物,Bi_(2)MoO_(6)凭借独特的层状结构引起研究者的广泛关注。然而,由于高的载流子复合率限制了其在光催化技术中的应用。本文重点总结概括对Bi_(2)MoO_(6)基光催化剂性能改性的策略,如表面结构调控、缺陷工程、金属沉积、构建异质结及光敏化处理。在诸多改性策略中重点论述Bi_(2)MoO_(6)基异质结的构建对光催化性能的影响。并对Bi_(2)MoO_(6)基光催化剂当前在光催化技术中面临的挑战及未来的发展前景进行展望,为加快Bi_(2)MoO_(6)基光催化剂的发展提供新思路。

Photonic topological transition in dimerized chains with the joint modulation of near-field and far-field couplings

Topological systems containing near-field or far-field couplings between unit cells have been widely investigated in quantum and classic systems.Their band structures are well explained with theories based on tight-binding or multiple scattering formalism.However,characteristics of the topology of the bulk bands based on the joint modulation of near-field and far-field couplings are rarely studied.Such hybrid systems are hardly realized in real systems and cannot be described by neither tight-binding nor multiple scattering theories.Here,we propose a hybrid-coupling photonic topological insulator based on a quasi-1D dimerized chain with the coexistence of near-field coupling within the unit cell and far-field coupling among all sites.Both theoretical and experimental results show that topological transition is realized by introducing near-field coupling for given far-field coupling conditions.In addition to closing and reopening the bandgap,the change in near-field coupling modulates the effective mass of photonics in the upper band from positive to negative,leading to an indirect bandgap,which cannot be achieved in conventional dimerized chains with either far-field or near-field coupling only.

Topological bound state in the continuum induced unidirectional acoustic perfect absorption

The interaction between cavity field and atoms plays an important role in exploring the abundant non-Hermitian physics and constructing powerful wave function devices.In this work,we propose theoretically and realize experimentally unidirectional perfect absorption in a non-Hermitian acoustic system with the help of the topological bound state in the continuum(BIC),which is established by the hybrid interaction between one trivial BIC and another conventional resonant state.In the 2D parameter space spanned by frequency and distance between the two resonators,the topological scattering singularities appear in pairs and are associated with topological distinguished charges.Meanwhile,we reveal the origin of topological charges and their continuous evolution with the loss factor.At a specific loss factor,two topological charges just annihilate together,and acoustic perfect absorption induced by topological BIC is realized at the left incidence,while there is no phase singularity and near-total reflection is observed at the right incidence,hence the system presents extreme asymmetry.Our work bridges the gap between scattering characteristics of non-Hermitian acoustic systems and topological scattering singularities,which may contribute to the research of novel non-Hermitian physics and the practical applications of advanced absorbers and sensors.

A new FTO/TiO_(2)/PbO_(2)electrode for eco-friendly electrochemical determination of chemical oxygen demand

Eco-friendly chemical oxygen demand(COD)sensors are highly desired with respect to the importance of COD determination in environmental protection.In this work,a new FTO/TiO_(2)/PbO_(2)(FTO=fluorine-doped tin oxide)electrode was fabricated with a two-step method and used as an eco-friendly electrochemical COD sensor.The interlayer TiO_(2)was employed to strengthen the adhesion of PbO_(2)on the FTO substrates by providing a large TiO_(2)/PbO_(2)interface area.The effects of the factors including applied potential,supporting electrolyte concentration and stirring speed on the sensing performance were investigated.Under the optimized conditions,linear responses to the COD of water with different COD sources were achieved,and a linear range from 5 to 120 mg/L was obtained in the case of sucrose as the COD source.The relative standard deviations(RSD)were determined to be less than 9%for the glucose solutions with the COD of 7.5,12.5 and 17.5 mg/L.For real sample analysis,the obtained results were comparable with those measured with the conventional dichromate method,with a relative error less than 11%.

Steerable merging bound states in the continuum on a quasi-flatband of photonic crystal slabs without breaking symmetry

Optical resonators with high quality(Q)factors are paramount for the enhancement of light–matter interactions in engineered photonic structures,but their performance always suffers from the scattering loss caused by fabrication imperfections.Merging bound states in the continuum(BICs)provide us with a nontrivial physical mechanism to overcome this challenge,as they can significantly improve the Q factors of quasi-BICs.However,most of the reported merging BICs are found atΓpoint(the center of the Brillouin zone),which intensively limits many potential applications based on angular selectivity.To date,studies on manipulating merging BICs at off-Γpoint are always accompanied by the breaking of structural symmetry that inevitably increases process difficulty and structural defects to a certain extent.Here,we propose a scheme to construct merging BICs at almost an arbitrary point in momentum space without breaking symmetry.Enabled by the topological features of BICs,we merge four accidental BICs with one symmetry-protected BIC at theΓpoint and merge two accidental BICs with opposite topological charges at the off-Γpoint only by changing the periodic constant of a photonic crystal slab.Furthermore,the position of off-Γmerging BICs can be flexibly tuned by the periodic constant and height of the structure simultaneously.Interestingly,it is observed that the movement of BICs occurs in a quasi-flatband with ultra-narrow bandwidth.Therefore,merging BICs in a tiny band provide a mechanism to realize more robust ultrahigh-Q resonances that further improve the optical performance,which is limited by wide-angle illuminations.Finally,as an example of application,effective angle-insensitive second-harmonic generation assisted by different quasi-BICs is numerically demonstrated.Our findings demonstrate momentum-steerable merging BICs in a quasi-flatband,which may expand the application of BICs to the enhancement of frequency-sensitive light–matter interaction with angular selectivity.

The mechanism of copper homeostasis and its role in disease

Copper(Cuprum)is an essential trace metal indispensable for the function of numerous enzymatic molecules implicated in cellular metabolism.Emerging evidence has demonstrated the role of copper in angiogenesis and cellular signaling.Moreover,raised copper levels have been detected in hepatocellular carcinoma and other cancers.An inherited or acquired copper imbalance,including inadequately low or excessively high copper levels,as well as inappropriate copper distribution in the body,is implicated in a number of diseases.In addition,a recent groundbreaking study identified a copperinduced type of programmed cell death named cuprotosis,the mechanism of which greatly deferred from that of other known cell death modes.The first part provides an overview of the regulation of copper homeostasis and discusses the underlying mechanisms of cuprotosis.In the second part,the authors focus on the functions of copper in liver diseases and other metabolic disorders,before discussing how this knowledge could contribute to the development of effective targets to treat such diseases.

Role of deubiquitinating enzymes in DNA double-strand break repair

DNA is the hereditary material in humans and almost all other organisms. It is essential for maintaining accurate transmission of genetic information. In the life cycle, DNA replication, cell division, or genome damage, including that caused by endogenous and exogenous agents, may cause DNA aberrations. Of all forms of DNA damage, DNA double-strand breaks(DSBs) are the most serious. If the repair function is defective, DNA damage may cause gene mutation, genome instability, and cell chromosome loss, which in turn can even lead to tumorigenesis. DNA damage can be repaired through multiple mechanisms. Homologous recombination(HR) and non-homologous end joining(NHEJ) are the two main repair mechanisms for DNA DSBs. Increasing amounts of evidence reveal that protein modifications play an essential role in DNA damage repair.Protein deubiquitination is a vital post-translational modification which removes ubiquitin molecules or polyubiquitinated chains from substrates in order to reverse the ubiquitination reaction. This review discusses the role of deubiquitinating enzymes(DUBs) in repairing DNA DSBs. Exploring the molecular mechanisms of DUB regulation in DSB repair will provide new insights to combat human diseases and develop novel therapeutic approaches.

Reproductive toxicity and underlying mechanisms of di(2-ethylhexyl) phthalate in nematode Caenorhabditis elegans

DEHP(di(2-ethylhexyl) phthalate) is an endocrine disruptor commonly found in plastic products that has been associated with reproduction alterations, but the effect of DEHP on toxicity is still widely unknown. Using DEHP concentrations of 10, 1, and 0.1 mg/L, we showed that DEHP reduced the reproductive capacity of Caenorhabditis elegans after 72 hr. of exposure. DEHP exposure reduced the reproductive capacity in terms of decreased brood sizes, egg hatchability(0.1, 1 and 10 mg/L), and egg-laying rate(1 and 10 mg/L), and increased numbers of fertilized eggs in the uterus(1 and 10 mg/L). DEHP also caused damage to gonad development. DEHP decreased the total number of germline cells, and decreased the relative area of the gonad arm of all exposure groups, with worms in the 1 mg/L DEHP exposure group having the minimum gonad arm area. Additionally, DEHP caused a significant concentration-dependent increase in the expression of unc-86. Autophagy and ROS contributed to the enhancement of DEHP toxicity in reducing reproductive capacity, and glutathione peroxidase and superoxide dismutase were activated as the antioxidant defense in this study. Hence, we found that DEHP has a dual effect on nematodes. Higher concentration(10 mg/L) DEHP can inhibit the expression of autophagy genes( atg-18, atg-7, bec-1, lgg-1 and unc-51), and lower concentrations(0.1 and 1 mg/L) can promote the expression of autophagy genes. Our data highlight the potential environmental risk of DEHP in inducing reproductive toxicity toward the gonad development and reproductive capacity of environmental organisms.

Ultrathin tellurium nanosheets for simultaneous cancer thermo-chemotherapy

The emerging two-dimensional monoelemental materials(2D Xenes)have been commonly supposed as promising drug delivery carriers,photothermal and photodynamic therapeutic agents,biosensors,theranostics,and some other candidates for biomedical applications.Here,high-performance and bioactive ultrathin 2D Tellurium nanosheets(Te NSs)are prepared by a simple but efficient liquid-phase exfoliation approach.The as-obtained Te NSs possess a mean size of~90 nm and a mean thickness of~5.43 nm.The pegylation Te NSs(Te-PEG NSs)possess excellent biocompatibility and stability.The Te-PEG NSs could generate local hyperthermia with a remarkable photothermal conversion efficiency of about 55%under 808 nm laser irradiation.Additionally,Te-PEG NSs exhibit an extremely high loading capacity of chemo drug(~162%)owing to their ultra-high surface area and tumor microenvironment-triggered drug release superiority.The results of in vivo experiments show that the Te-PEG NSs have higher tumor elimination efficiency via the combination of photothermal and chemotherapy,comparing to any other single therapeutic modalities.Therefore,our work not only highlights the promising potentials of tellurene as an ideal anti-cancer platform but also expands the application of 2D Te for cancer nanomedicine.