The energy response of LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals for GECAM

The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity in the detection of low-energy gamma rays and address the errors in the calibration of the E-C relationship,comprehensive tests and comparative studies of the three aforementioned crystals were conducted using Compton electrons,radioactive sources,and mono-energetic X-rays.The nonlinearity test results of the Compton electrons and X-rays demonstrated substantial differences,with all three crystals presenting a higher nonlinearity for X/-rays than for Compton electrons.Despite the LaBr_(3)(Ce)and LaBr_(3)(Ce,Sr)crystals having higher absolute light yields,they exhibited a noticeable nonlinear decrease in the light yield,especially at energies below 400 keV.The NaI(Tl)crystal demonstrated an"excess"light output in the 6-200 keV range,reaching a maximum"excess"of 9.2%at 30 keV in the X-ray testing and up to 15.5%at 14 keV during Compton electron testing,indicating a significant advantage in the detection of low-energy gamma rays.Furthermore,we explored the underlying causes of the observed nonlinearity in these crystals.This study not only elucidates the detector responses of GECAM,but also initiates a comprehensive investigation of the nonlinearity of domestically produced lanthanum bromide and sodium iodide crystals.

Mechanical property of cylindrical sandwich shell with gradient core of entangled wire mesh

To explore the wide-frequency damping and vibration-attenuation performances in the application of aerospace components,the cylindrical sandwich shell structure with a gradient core of entangled wire mesh was proposed in this paper.Firstly,the gradient cores of entangled wire mesh in the axial and radial directions were prepared by using an in-house Numerical Control weaving machine,and the metallurgical connection between skin sheets and the gradient core was performed using vacuum brazing.Secondly,to investigate the mechanical properties of cylindrical sandwich shells with axial or radial gradient cores,quasi-static and dynamic mechanical experiments were carried out.The primary evaluations of mechanical properties include secant stiffness,natural frequency,Specific Energy Absorption(SEA),vibration acceleration level,and so on.The results suggest that the vibration-attenuation performance of the sandwich shell is remarkable when the high-density core layer is at the end of the shell or abuts the inner skin.The axial gradient material has almost no influence on the vibration frequencies of the shell,whereas the vibration frequencies increase dramatically when the high-density core layer approaches the skin.Moreover,compared to the conventional sandwich shells,the proposed functional grading cylindrical sandwich shell exhibits more potential in mass reduction,stiffness designing,and energy dissipation.

Impact response and energy absorption of metallic buffer with entangled wire mesh damper

An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering equipment.The impact response and the energy dissipation mechanism of hat-shaped EWMD under different quasi-static compression deformations(2-7 mm)and impact heights(100-200 mm)are investigated using experimental and numerical methods.The results demonstrate distinct stages in the quasi-static mechanical characteristics of hat-shaped EWMD,including stiffness softening,negative stiffness,and stiffness hardening.The loss factor gradually increases with increasing compression deformation before entering the stiffness hardening stage.Under impact loads,the hat-shaped EWMD exhibits optimal impact energy absorption when it enters the negative stiffness stage(150 mm),resulting in the best impact isolation effect of metallic buffer.However,the impact energy absorption significantly decreases when hat-shaped EWMD enters the stiffness hardening stage.Interestingly,quasi-static compression analysis after experiencing different impact loads reveals the disappearance of the negative stiffness phenomenon.Moreover,with increasing impact loads,the stiffness hardening point progressively shifts to an earlier stage.

Facies-controlled prediction of dolomite reservoirs in the Middle Permian Qixia Formation in Shuangyushi,northwestern Sichuan Basin

The Middle Permian Qixia Formation in the Shuangyushi area,northwestern Sichuan Basin,develops shoal-facies dolomite reservoirs.To pinpoint promising reservoirs in the Qixia Formation,deep thin shoal-facies dolomite reservoirs were predicted using the techniques of pre-stack Kirchhoff-Q compensation for absorption,inverse Q filtering,low-to high-frequency compensation,forward modeling,and facies-controlled seismic meme inversion.The results are obtained in six aspects.First,the dolomite reservoirs mainly exist in the middle and lower parts of the second member of Qixia Formation(Qi2 Member),which coincide with the zones shoal cores are developed.Second,the forward modeling shows that the trough energy at the top and bottom of shoal core increases with increasing shoal-core thickness,and weak peak reflections are associated in the middle of shoal core.Third,five types of seismic waveform are identified through waveform analysis of seismic facies.Type-Ⅰ and Type-Ⅱ waveforms correspond to promising facies(shoal core microfacies).Fourth,vertically,two packages of thin dolomite reservoirs turn up in the sedimentary cycle of intraplatform shoal in the Qi2 Member,and the lower package is superior to the upper package in dolomite thickness,scale and lateral connectivity.Fifth,in plane,significantly controlled by sedimentary facies,dolomite reservoirs laterally distribute with consistent thickness in shoal cores at topographical highs and extend toward the break.Sixth,the promising prospects are the zones with thick dolomite reservoirs and superimposition of horstegraben structural traps.

A Localization Method of High Energy Transients for All-sky Gamma-ray Monitor

Fast and reliable localization of high-energy transients is crucial for characterizing the burst properties and guiding the follow-up observations.Localization based on the relative counts of different detectors has been widely used for all-sky gamma-ray monitors.There are two major methods for this count distribution localization:χ^(2)minimization method and the Bayesian method.Here we propose a modified Bayesian method that could take advantage of both the accuracy of the Bayesian method and the simplicity of the χ^(2)method.With comprehensive simulations,we find that our Bayesian method with Poisson likelihood is generally more applicable for various bursts than the χ^(2)method,especially for weak bursts.We further proposed a location-spectrum iteration approach based on the Bayesian inference,which could alleviate the problems caused by the spectral difference between the burst and location templates.Our method is very suitable for scenarios with limited computation resources or timesensitive applications,such as in-flight localization software,and low-latency localization for rapidly follow-up observations.

The In-Flight Realtime Trigger and Localization Software of GECAM

Realtime trigger and localization of bursts are the key functions of GECAM,an all-sky gamma-ray monitor launched on 2020 December 10.We developed a multifunctional trigger and localization software operating in the CPU of the GECAM Electronic Box.This onboard software has the following features:high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation,dedicated localization algorithm optimized for both short and long bursts,and low time latency of the trigger information which is downlinked through the Global Short Message Communication service of the global BeiDou navigation system.This paper provides a detailed description of the design and development of the trigger and localization software system for GECAM.It covers the general design,workflow,the main functions,and the algorithms used in the system.The paper also includes on-ground trigger tests using simulated gamma-ray bursts generated by a dedicated X-ray tube,as well as an overview of the performance for real celestial bursts during its in-orbit operation.

The Design of GECAM Scientific Ground Segment

The Gravitational wave burst high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)is a dedicated mission for monitoring high-energy transients.Here we report the design of the GECAM Scientific Ground Segment(GSGS)in terms of the scientific requirements,including the architecture,the external interfaces,the main function,and workflow.Judging from the analysis and verification results during the commissioning phase,the GSGS functions well and is able to monitor the status of the payloads,adjust the parameters,develop the scientific observation plans,generate the scientific data products,analyze the data,etc.Thus,the on-orbit operation and scientific researches of GECAM are guaranteed.

In-flight Energy Calibration of the GECAM Gamma-ray Detectors

The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)mission is designed to monitor the Gamma-Ray Bursts(GRBs)associated with gravitational waves and other high-energy transient sources.The mission consists of two microsatellites which are planned to operate at the opposite sides of the Earth.Each GECAM satellite could detect and localize GRBs in about 8 keV-5 MeV with its 25 Gamma-Ray Detectors(GRDs).In this work,we report the in-flight energy calibration of GRDs using the characteristic gamma-ray lines in the background spectra,and show their performance evolution during the commissioning phase.Besides,a preliminary cross-calibration of energy response with Fermi GBM data is also presented,validating the energy response of GRDs.

核电机组堆内部件转运方法优化研究

某核电厂进行堆芯换料前,先将堆内部件转移至堆内部件检查井存放,完成换料后,再将堆内部件转运并回装至反应堆内。本文在总结核电厂现有堆内部件转运经验的基础上,利用现有系统设备,通过调整工作方法对原有方法从两方面提出了优化。此方法通过优化关键路径的操作,可节约大修时间,节约现场人员的工作量,同时具有良好的经济效益。

核电厂凝汽器真空系统真空泵运行方式优化研究

某百万千瓦级核电站设计采用三台水环式真空泵为凝汽器建立并维持真空,正常为两运一备,真空泵与凝汽器均为海水冷却。通过计算,分析了夏季时该电厂凝汽器真空的极限值以及真空泵的运行情况,得出在夏季该电厂凝汽器真空存在优化的潜力,并提出了对真空泵运行方式的优化。

2023 ASCO-GU前列腺癌研究进展快递

2023年美国临床肿瘤学会泌尿男生殖系肿瘤研讨会报道的多项研究进展对临床选择前列腺癌治疗方案有重要指导意义。依据人群特性开展精准化的多联疗法已成为前列腺癌治疗的主流趋势,包括转移性激素敏感性前列腺癌中的三药联合治疗及转移性去势抵抗性前列腺癌中的多腺苷二磷酸核糖聚合酶抑制剂联合治疗。此外,核素治疗和放疗也受到较多关注。在非转移性去势抵抗性前列腺癌中,核素诊疗一体化具有巨大潜力。对于局限性前列腺癌,立体定向放疗则成为手术之外的优先选项。本文通过解析会上多项不同阶段前列腺癌的重磅研究,以期使更多前列腺癌患者在治疗中获益。

高超声速导弹随机振动响应分析

目的 研究某高超声速导弹飞行过程中的振动状态,获得导弹在给定压力载荷下的振动响应特性。方法结合有限元分析、随机振动理论,利用三维软件构建导弹有限元模型,并在Ansys Workbench平台对其进行模态分析及谐响应分析。基于模态分析结果,对导弹进行随机振动响应试验,探究导弹在频域及力学上的振动响应特征。结果 计算得出导弹前六阶固有频率和振型,获得导弹上一检测点在给定振动激励载荷下的加速度响应曲线,并得到导弹整体结构的应力分布云图。结论 导弹模型强度符合要求,导弹在振动激励载荷下的加速度响应峰值均出现在380~400Hz,应力极值出现在导弹尾部区域,在此区域内,导弹更易产生结构性损伤。在飞行器地面环境模拟试验中,应着重考虑此频域及位置的振动条件。

An Isogeometric Cloth Simulation Based on Fast Projection Method

A novel continuum-based fast projection scheme is proposed for cloth simulation.Cloth geometry is described by NURBS,and the dynamic response is modeled by a displacement-only Kirchhoff-Love shell element formulated directly on NURBS geometry.The fast projection method,which solves strain limiting as a constrained Lagrange problem,is extended to the continuum version.Numerical examples are studied to demonstrate the performance of the current scheme.The proposed approach can be applied to grids of arbitrary topology and can eliminate unrealistic over-stretching efficiently if compared to spring-based methodologies.

中国对亚洲新兴市场国家农产品出口效率研究

本文采用2002—2017年8个亚洲新兴市场国家农产品贸易的面板数据,利用时变随机前沿引力模型估计了中国对亚洲其他新兴市场国家农产品的出口效率,并在此基础上探索了影响出口贸易额和出口效率的主要因素。结果显示:中国对亚洲其他新兴市场国家农产品出口效率有一直提升的趋势,但总体上出口效率较低;中国以及亚洲其他新兴市场国家的经济规模和人口规模对农产品出口贸易有明显的促进作用,而两国之间的地理距离则与农产品出口贸易额具有显著的负向关系;国家的贸易依存度及两国间的自由贸易协定有助于提升中国对亚洲其他新兴市场国家农产品出口的贸易效率。本文的研究在"一带一路"大背景下具有理论和实践的双重意义。

一款含鲜奶面霜对面部皮肤细菌多样性的影响研究

利用高通量测序技术研究使用一款含鲜奶面霜后对皮肤细菌多样性的影响。通过随机抽取10名使用含鲜奶面霜的受试者(女性,平均年龄24.1±0.9岁)并用棉拭子采集面颊皮肤样本,提取DNA及PCR扩增后,进行16S rRNA高通量测序,并根据97%的相似度对序列进行OTU聚类和物种分类注释,分析比较使用样品前后皮肤细菌群落组成、多样性和差异菌群。研究发现使用含鲜奶面霜后脸颊皮肤细菌的多样性降低,但受试者面颊皮肤的细菌种类及相对丰度较为相似,同时受试者皮肤菌群中的厚壁菌门和放线菌门比例明显升高,这主要是由厚壁菌门中的葡萄球菌属和放线菌门中的丙酸杆菌属比例升高导致的。结果表明此款含鲜奶面霜对皮肤菌群微生态发挥一定的调节作用,且具有滋润保湿的效果,可以作为日常护肤中的保湿产品使用。

一种基于SMOTE和XGBoost的窃电检测方案

用户侧窃电行为造成的非技术损失不仅增加了电网的运营成本,还会干扰电力系统稳态。现有的检测方案忽略了用电数据的时序性及正负样本分布不均、维度高的问题,这将极大地影响检测的准确率。因此,提出了一种基于SMOTE和XGBoost的窃电检测方案。针对电力数据的时序性和类不平衡的特点,利用SMOTE算法进行过采样解决了数据不平衡的问题,并构造时序特征挖掘用户用电模式;再使用XGBoost执行用电数据的特征提取和分类过程。实验表明,通过SMOTE算法可以提高不平衡数据分类的有效性,对比于传统的检测模型,XGBoost算法在窃电检测场景的多项评价指标下均取得了更好的效果,其中准确率提升至92.45%。

The chromosome-scale genome reveals the evolution and diversification after the recent tetraploidization event in tea plant

Tea is one of the most popular nonalcoholic beverages due to its characteristic secondary metabolites with numerous health benefits.Although two draft genomes of tea plant(Camellia sinensis)have been published recently,the lack of chromosome-scale assembly hampers the understanding of the fundamental genomic architecture of tea plant and potential improvement.Here,we performed a genome-wide chromosome conformation capture technique(Hi-C)to obtain a chromosome-scale assembly based on the draft genome of C.sinensis var.sinensis and successfully ordered 2984.7 Mb(94.7%)scaffolds into 15 chromosomes.The scaffold N50 of the improved genome was 218.1 Mb,~157-fold higher than that of the draft genome.Collinearity comparison of genome sequences and two genetic maps validated the high contiguity and accuracy of the chromosome-scale assembly.We clarified that only one Camellia recent tetraploidization event(CRT,58.9–61.7 million years ago(Mya))occurred after the core-eudicot common hexaploidization event(146.6–152.7 Mya).Meanwhile,9243 genes(28.6%)occurred in tandem duplication,and most of these expanded after the CRT event.These gene duplicates increased functionally divergent genes that play important roles in tea-specific biosynthesis or stress response.Sixty-four catechin-and caffeine-related quantitative trait loci(QTLs)were anchored to chromosome assembly.Of these,two catechin-related QTL hotspots were derived from the CRT event,which illustrated that polyploidy has played a dramatic role in the diversification of tea germplasms.The availability of a chromosome-scale genome of tea plant holds great promise for the understanding of genome evolution and the discovery of novel genes contributing to agronomically beneficial traits in future breeding programs.

Restoring the dampened expression of the core clock molecule BMAL1 protects against compression-induced intervertebral disc degeneration

The circadian clock participates in maintaining homeostasis in peripheral tissues,including intervertebral discs(IVDs).Abnormal mechanical loading is a known risk factor for intervertebral disc degeneration(IDD).Based on the rhythmic daily loading pattern of rest and activity,we hypothesized that abnormal mechanical loading could dampen the IVD clock,contributing to IDD.Here,we investigated the effects of abnormal loading on the IVD clock and aimed to inhibit compression-induced IDD by targeting the core clock molecule brain and muscle Arnt-like protein-1(BMAL1).In this study,we showed that BMAL1 KO mice exhibit radiographic features similar to those of human IDD and that BMAL1 expression was negatively correlated with IDD severity by systematic analysis based on 149 human IVD samples.The intrinsic circadian clock in the IVD was dampened by excessive loading,and BMAL1 overexpression by lentivirus attenuated compression-induced IDD.Inhibition of the RhoA/ROCK pathway by Y-27632 or melatonin attenuated the compression-induced decrease in BMAL1 expression.Finally,the two drugs partially restored BMAL1 expression and alleviated IDD in a diurnal compression model.Our results first show that excessive loading dampens the circadian clock of nucleus pulposus tissues via the RhoA/ROCK pathway,the inhibition of which potentially protects against compression-induced IDD by preserving BMAL1 expression.These findings underline the importance of the circadian clock for IVD homeostasis and provide a potentially effective therapeutic strategy for IDD.

SCN掺杂提高CsPbI_(3)胶体量子点的稳定性和光探测性能

无机卤化物钙钛矿CsPbI_(3)胶体量子点因其优越的光电性能在光伏和发光器件领域中表现出极大的发展前景。然而,CsPbI_(3)较差的稳定性阻碍了实际应用。为此,我们采用SCN−离子掺杂CsPbI_(3)(SCN-CsPbI_(3))量子点用于提高量子点的光学性能和稳定性。研究表明,SCN−离子掺杂不仅减少了量子点缺陷、改善了光学性能,还提高了Pb-X键能、量子点结晶质量以及钙钛矿结构稳定性。结果表明,SCN-CsPbI_(3)量子点的荧光量子产率(PLQY)超过90%,远高于未掺杂原始样品(PLQY为68%)。高的荧光量子产率表明量子点具有较低的缺陷态密度,这归咎于缺陷的减少。空间限制电荷和时间分辨荧光光谱等研究也证实SCN−离子掺杂减少了量子点的缺陷。此外,SCN-CsPbI_(3)量子点展现出很好的抗水性能,其荧光强度在水中浸泡4 h后依然保持85%的初始值。而未掺杂原始样品的荧光性能很快消失,这是因为水诱导其相变。基于SCN-CsPbI_(3)量子点的光电探测器表现出宽波域响应(400–700 nm),高的响应率(90 mA·W^(−1))和超过1011 Jones的探测度,远高于未掺杂原始量子点探测器的性能(响应率为60 mA·W^(−1)和探测度为1010 Jones)。

Carbon nanotubes for supercapacitors:Consideration of cost and chemical vapor deposition techniques

In this topic, we first discussed the requirement and performance of supercapacitors using carbon nanotubes （CNTs） as the electrode, including specific surface area, purity and cost. Then we reviewed the preparation technique of single wailed CNTs （SWNTs） in relatively large scale by chemical vapor deposition method. Its catalysis on the decomposition of methane and other carbon source, the reactor type and the process control strategies were discussed. Special focus was concentrated on how to increase the yield, selectivity, and purity of SWNTs and how to inhibit the formation of impurities, including amorphous carbon, multiwalled CNTs and the carbon encapsulated metal particles, since these impurities seriously influenced the performance of SWNTs in supercapacitors. Wish it be helpful to further decrease its product cost and for the commercial use in supercapacitors.