橡胶材料的非线性黏弹性本构方程

橡胶是一种非线性黏弹性材料,准确描述其非线性黏弹性力学响应的本构方程是橡胶材料及制品设计优化的关键。文中基于超弹性模型和并行流变模型(PRF)描述了橡胶材料的非线性黏弹性响应特征,重点探讨了由实验数据确定PRF本构方程材料参数的方法。首先通过单轴拉伸实验数据拟合得到超弹性模型,将应力松弛实验数据拟合得到表征材料线性黏弹性的模型-Prony级数,再将Prony级数转化为初始的PRF模型,进而不断优化得到PRF模型的准确材料参数,最后进行实验验证。结果表明,PRF模型计算的不同应变下的应力松弛数据与实验数据之间的误差仅为0.067%,PRF能准确地描述橡胶材料非线性响应的应力松弛行为。

基于非线性黏弹性本构模型的轮胎滚动和生热

轮胎的滚动阻力和自生热是造成轮胎失效的原因之一,轮胎内部能量的产生主要取决于轮胎中橡胶材料的黏弹性能量耗散。文中基于超弹性模型和并行流变模型(PRF)描述了橡胶材料的非线性黏弹性响应特征,提出了一种预测实心轮胎温度分布和滚动阻力的方法。首先将线性黏弹性Prony级数转化为PRF模型的初始参数,并利用Isight软件根据多应变工况加载得到的应力松弛测试数据来校准材料参数,然后采用显式-热力耦合分析方法分析基于Prony级数和PRF模型的实心轮胎滚动过程的差异。结果表明,Prony级数无法描述橡胶材料的非线性行为,在显式动力学下计算的轮胎生热结果为0;PRF模型可以表征橡胶材料的非线性行为,并且计算的轮胎模型在0.3s内温度上升了0.14℃。

Calibration of Mars Energetic Particle Analyzer (MEPA)

The first Mars exploration mission of China(Tianwen-1)is scheduled to be launched in 2020;a charged particle telescope,the Mars Energetic Particle Analyzer(MEPA),is carried as one of the payloads on the orbiter.The MEPA is designed to measure solar energetic particles(SEPs)and galactic cosmic rays(GCRs)in the near-Mars space and in the transfer orbit from Earth to Mars.Before the launch,the MEPA was calibrated in ground experiments with radioactive sources,electronic pulses,and accelerator beams.The calibration parameters,such as energy conversion constants,threshold values for the triggers,and particle identification criteria,were determined and have been stored for onboard use.The validity of the calibration parameters has been verified with radioactive sources and beams.The calibration results indicate that the MEPA can measure charged particles reliably,as designed,and that it can satisfy the requirements of the Tianwen-1 mission.

Psychometric properties of the Chinese version of the Arabic Scale of Death Anxiety

背景:死亡焦虑被视为精神病理学症状的风险因素和持续存在的因素。虽然阿拉伯死亡焦虑量表(ASDA)是一种简单而常用的评估工具,但是在国内临床实践中缺少这样的工具。目标:本研究旨在采用多级回译法开发ASDA中文版,即ASDA(C),并研究该量表的心理测量学特性。方法:从国内三个地区的医院和大学共招募了1372名参试者。为了计算出ASDA(C)的效标相关效度与有关死亡和死亡清单的多维度取向表格中文版(MODDI-F/chin)相比较,随机指定49名大学生完成这两份调查问卷。在所有参试者中随机指定56名再做一次ASDA(C)问卷调查,来评估ASDA(C)的一周后重测信度。结果:量表总的Cronbach’sα值为0.91。一周后的重测信度为0.96。探索性因子分析(EFA)显示三个因素,"对死人和坟墓的恐惧,"对致命疾病的恐惧"和"对死亡事件的恐惧",占总方差的57.09%。因而构建三因素模型。量表ASDA(C)总分与MODDI-F/chin的相关系数是0.54,表示信度都可以接受。结论:ASDA(C)有较好的心理测量学特性,说明这是一个可靠有效的量表。该量表能用于讲普通话的中国人群,来评估死亡焦虑。

Supramolecular flow chemistry: Construction of multiscale supramolecular assemblies by micro/nanofluidic techniques

The rapid and precise fabrication of multiscale supramolecular assemblies using micro/nanofluidic techniques has emerged as a dynamic area of research in supramolecular chemistry, materials chemistry, and organic chemistry. This review summarizes the application of micro/nanofluidic techniques in constructing supramolecular assemblies, including nanoscale supramolecular assemblies such as macrocycles and cages, microscale supramolecular assemblies such as metal organic frameworks (MOFs) and covalent organic frameworks (COFs), and macroscale supramolecular assemblies such as supramolecular hydrogels. Compared to conventional synthesis methods, micro/nanofluidic techniques for the production of supramolecular assemblies have significant advantages, including enhanced safety, high reaction rates, improved selectivity/yield, and scalability. Additionally, micro/nanofluidic systems facilitate the creation of precisely controllable micro/nanoconfined environments, allowing for a unique flow behavior that improves our understanding of the supramolecular self-assembly process. Such systems may also lead to the development of novel supramolecular assemblies that differ from those generated via traditional methods.

基于FPGA的AMC信号处理卡的设计与实现

国内外早期,探测器装置的数据传输系统普遍采用并行总线架构,如VME、PXI总线等。随着核物理实验的发展,数据的传输速度不断提高,并行总线难以提速的弊端逐渐显现,总线速度不够导致数据无法通过背板传输。本工作采用基于MicroTCA(Micro Telecom Computing Architecture)架构设计一种新型先进的数据传输AMC(Advanced Mezzanine Card)信号处理卡。该AMC信号处理卡的背板总线使用在速度提升方面有着巨大优势的高速PCIe串行总线。通过测试验证,整个传输链路传输功能正确,链路传输的光纤误码率低于7.62×10^(−15),传输速度也接近理论的极值,达到了430 MB/s。最后,该AMC信号处理卡与前端电子学进行了联测,验证了系统的正确性。

Characteristics of the three-dimensional deep electrical structure in the Helan Mountains-Yinchuan Basin and its geodynamic implications

Located in the north segment of the North-South seismic belt where the Alxa block(AB)and the Ordos block(OB)contact,the Helan Mountains-Yinchuan Basin(HLM-YCB)constitutes a typical normal faulting basin-mountain structure on the Chinese mainland.The 1739 M8.0 Pingluo earthquake occurred in the Yinchuan fault depression basin with such a basinmountain structure.Data on five magnetotelluric profiles encompassing distinct segments of the HLM-YCB were utilized for three-dimensional(3D)joint inversion in order to collect fine 3D electrical structure information at a crustal and upper mantle scale across the entire region.The electrical structure between the main blocks in the HLM-YCB and adjacent areas is characterized by east-west horizontal blocks OB,YCB,and HLM,which are divided by the Yellow River fault(F5)with the HLM eastern piedmont fault(F2)as electrical boundary zones on the east and west sides.The two main block units,AB and OB,exhibit an obvious layered resistivity structure.Besides,the HLM-YCB is characterized by a typical basin-mountain structure with the mountains as a high-resistivity body and the basin as a low-resistivity body,and in the northern YCB a large-scale lowresistivity structure exists,extending to the upper mantle,probably derived from the upwelling of mantle-derived materials.It is speculated from a combination of recent 3D crustal movement field information and other data that the HLM-YCB is an active tectonic zone formed via regional tensile action.The formation of the HLM-YCB lies in the interaction of the Tibetan Plateau(TP),AB,and OB and abnormal mantle activities beneath the YCB.The HLM-YCB reflects the joint action of upwelling and diffluence caused by the underplating of hot materials from the deep mantle with gravity and the redistribution of regional tectonic stress on the earth’s surface,which may be the main dynamic reason for the 1739 M8.0 Pingluo earthquake.

聚集诱导发光

聚集诱导发光(AIE)是唐本忠院士于2001年提出的一个科学概念,是指一类在溶液中不发光或者发光微弱的分子聚集后发光显著增强的现象。高效固态发光的AIE材料有望从根本上解决有机发光材料面临的聚集导致发光猝灭难题,具有重大的实际应用价值。从分子内旋转受限到分子内运动受限,从聚集诱导发光到聚集体科学,AIE领域已经取得了许多原创性的成果。在本综述中,我们从AIE材料的分类、机理、概念衍生、性能、应用和挑战等方面讨论了AIE领域最近取得的显著进展。希望本综述能激发更多关于分子聚集体的研究,并推动材料、化学和生物医学等学科的进一步交叉融合和更大发展。

Study of the temporal and spatial patterns of drought in the Yellow River basin based on SPEI

Drought is one of the severe natural disasters to impact human society and occurs widely and frequently in China,causing considerable damage to the living environment of humans.The Yellow River basin(YRB)of China shows great vulnerability to drought in the major basins;thus,drought monitoring in the YRB is particularly important.Based on monthly data of 124 meteorological stations from 1961 to 2015,the Standardized Precipitation Evapotranspiration Index(SPEI)was used to explore the temporal and spatial patterns of drought in the YRB.The periods and trends of drought were identified by Extreme-point Symmetric Mode Decomposition(ESMD),and the research stages were determined by Bernaola-Galvan Segmentation Algorithm(BGSA).The annual and seasonal variation,frequency and intensity of drought were studied in the YRB.The results indicated that(1)for the past 55 years,the drought in the YRB has increased significantly with a tendency rate of-0.148(10 a)^(-1),in which the area Lanzhou to Hekou was the most vulnerable affected(-0.214(10 a)^(-1));(2)the drought periods(2.9,5,10.2 and 18.3 years)and stages(1961–1996,1997–2002 and 2003–2015)were characterized and detected by ESMD and BGSA;(3)the sequence of drought frequency was summer,spring,autumn and winter with mean values of 71.0%,47.2%,10.2%and 6.9%,respectively;and(4)the sequence of drought intensity was summer,spring,winter and autumn with mean values of 0.93,0.40,0.05 and 0.04,respectively.

Genomic insights into the fast growth of paulownias and the formation of Paulownia witches' broom

Paulownias are among the fastest growing trees in the world,but they often suffer tremendous loss of wood production due to infection by Paulownia witches'broom(PaWB)phytoplasmas.In this study,we have sequenced and assembled a high-quality nuclear genome of Paulownia fortunei,a commonly cultivated paulownia species.The assembled genome of P.fortunei is 511.6 Mb in size,with 93.2%of its sequences anchored to 20 pseudo-chromosomes,and it contains 31985 protein-coding genes.Phylogenomic analyses show that the family Paulowniaceae is sister to a clade composed of Phrymaceae and Orobanchaceae.Higher photosynthetic efficiency is achieved by integrating C3 photosynthesis and the crassulacean acid metabolism pathway,which may contribute to the extremely fast growth habit of paulownia trees.Comparative transcriptome analyses reveal modules related to cambial growth and development,photosynthesis,and defense responses.Additional genome sequencing of PaWB phytoplasma,combined with functional analyses,indicates that the effector PaWB-SAP54 interacts directly with Paulownia PfSPLa,which in turn causes the degradation of PfSPLa by the ubiquitin-mediated pathway and leads to the formation of witches'broom.Taken together,these results provide significant insights into the biology of paulownias and the regulatory mechanism for the formation of PaWB.

A novel lead-free Na_(0.5)Bi_(0.5)TiO_(3)-based ceramic with superior comprehensive energy storage and discharge properties for dielectric capacitor applications

Na_(0.5)Bi_(0.5)TiO_(3)(NBT)-based ceramics have been widely used as dielectric materials for energy storage capacitors because of their environmental friendliness and excellent ferroelectric properties.However,their energy storage performance still needs to be further improved to satisfy the increasing demand.Herein,we report a novel 0.90(Na_(0.5)Bi_(0.5))0.7Sr_(0.3)TiO_(3-0.10)Bi(Ni_(0.5)Sn_(0.5))O_(3)(0.90NBST-0.10BNS)ceramic with significantly improved energy density(5.0 J cm3),enhanced recoverable energy density(4.18 J cm^(3))and high energy efficiency(83.64%)through the incorporation of Bi(Ni0.5Sn0.5)O3(BNS),due to the increased breakdown strength and the relaxation ferroelectric(RFE)properties.The first-order reversal curve(FORC)measurements confirm that the addition of BNS improves RFE properties by breaking the order of long-range ferroelectricity.The 0.90NBST-0.10BNS ceramic also possesses an outstanding temperature and frequency stability of energy storage properties in the range of 20C e140C and 1 Hze100 Hz,respectively.More importantly,the discharge properties characterized by a preeminent power density(36.19 MW cm^(3)),transient energy release times(144.2 ns),and high discharge energy density(1.16 J cm3)also synchronously observed in 0.90NBST-0.10BNS ceramic.These results show that the 0.90NBST-0.10BNS ceramic with outstanding comprehensive performances is a promising energy storage ceramic candidate for capacitors in high power systems.

Fabrication of Neutral Supramolecular Polymeric Films via Post-electropolymerization of Discrete Metallacycles

Self-assembly post-modification has proven to be an efficient strategy to build higher-order supramolecular architectures and functional materials. In this study, we successfully realized the construction＇of a new family of neutral supramolecular polymeric films containing well-defined metallacycles as the main scaffolds through combination Of coordination-driven self-assembly with post-electropolymerization. The obtained neutral polymeric materials were fully characterized by the cyclic voltammogram （CV）, SEM, and TEM. The thickness of the films was able to be well regulated by the number of scanning cycles. Moreover, we found that the shape of the metallacycles and the number of triphenylamine moieties played important roles in the formation of the final polymer films. We believe that the introduction of the neutral metallacycles into the final polymer structures not only enriches the library of supramolecular polymeric films but also provides a new platform to study neutral molecule detection, separation, and capture.

Construction of Highly Emissive Pt(Ⅱ) Metallacycles upon Irradiation

Photoswitchable or photoactivatable fluorescent species have been found wide applications within supramolecular chemistry and materials science.In this study,we successfully constructed two highly emissive Pt(Ⅱ)metallacycles from the diarylethene ligands via coordination-driven self-assembly.Different from the most known fluorescent metallacycles,the obtained metallacycles have displayed"turn-on"fluorescence switching.They are non-fluorescent in solution,but they emit highly yellow or orange fluorescence under ultraviolet irradiation.The metallacycles were well characterized by 1H NMR,31P NMR and ESI-TOF-MS.The photochromic properties of the resultant metallacycles were investigated by 1H NMR,31P NMR,UV/Vis spectrum and fluorescence spectrum.Notably,NMR studies revealed that these two metallacycles featured excellent cyclization efficiency(90% conversion efficiency).Moreover,the closed-ring isomers of the metallacycles displayed relatively high quantum yield(ФF=0.5).DFT simulations demonstrated that the antiparallel configuration of the diarylethene ligand had an angle closed to 120°,which was more stable in energy compared to the parallel configuration,thus allowing for the facile construction of highly emissive metallacycles.We believe that such highly emissive metallacycles which are in-situ prepared upon irradiation can be used as new fluorescence materials for sensing and bioimaging in the future.

Two-dimensional CoNi@mesoporous carbon composite with heterogeneous structure toward broadband microwave absorber

Constructing composites with heterogeneous structure and dual loss mechanism shows great potential in designing microwave absorbers.In this work,two-dimensional cobalt and nickel alloys@mesoporous carbon(CoNi@MC)composites were constructed via using CoNi layered double hydroxide@mesoporous polydopamine(CoNi LDH@MPDA)as sacrifice template.During the pyrolysis process,the MPDA is transformed into mesoporous carbon coated the surface of CoNi LDH that is further reduced to CoNi alloys.The mesoporous structure is conducive to the multi-reflection of electromagnetic waves and facilitates optimizing impedance matching.Heterogeneous interfaces between CoNi alloys and mesoporous carbon induce interface polarization.Multiple attenuation mechanism promotes the electromagnetic waves conversion.The maximum reflection loss of CoNi@MC composite is−70.86 dB and the widest effective absorption bandwidth is 7.74 GHz covering almost the entire Ku band.This strategy will be a guidance for designing electromagnetic absorbers.

Harnessing the native type I-B CRISPR-Cas for genome editing in a polyploid archaeon

Research on CRISPR-Cas（clustered regularly interspaced short palindromic repeats-CRISPR associated protein） systems has led to the revolutionary CRISPR/Cas9 genome editing technique. However, for most archaea and half of bacteria, exploitation of their native CRISPR-Cas machineries may be more straightforward and convenient. In this study, we harnessed the native type I-B CRISPR-Cas system for precise genome editing in the polyploid haloarchaeon Haloarcula hispanica. After testing different designs, the editing tool was optimized to be a single plasmid that carries both the self-targeting miniCRISPR and a 600-800 bp donor. Significantly, chromosomal modifications, such as gene deletion, gene tagging or single nucleotide substitution, were precisely introduced into the vast majority of the transformants. Moreover, we showed that simultaneous editing of two genomic loci could also be readily achieved by one step. In summary, our data demonstrate that the haloarchaeal CRISPR-Cas system can be harnessed for genome editing in this polyploid archaeon, and highlight the convenience and efficiency of the native CRISPR-based genome editing strategy.

Self-assembly of Pyrene-modified Rhomboidal Metalloden- drimers via Directional Metal-ligand Bonding Approach

The design and self-assembly of pyrene-modified rhomboidal metallodendrimers R1--R6 via directional metal-ligand bonding approach is described. By employing pyrene-containing 120° di-Pt（II） acceptor and appropri- ate 60° dendritic dipyridyl donors, a variety of [G-1]--[G-3] pyrene-modified rhomboidal metallodendrimers with well-defined shape and size were prepared under mild conditions in high yields. The supramolecular dendrimers were characterized with multinuclear NMR （1H and 31p） and mass spectrometry （CSI-TOF-MS）. lsotopically re- solved mass spectrometry data support the existence of the pyrene-modified dendrimers with rhomboidal cavities, and NMR data were consistent with the formation of all ensembles. The shape and size of all rhomboidal den- drimers were investigated with the PM6 semiempirical molecular orbital method. Their primary photochemical properties were studied as well.

Deep brain stimulation for early-onset dystonia

Deep brain stimulation(DBS)is considered as a treatment option for many neurological diseases.Many patients with movement disorders exhibit remarkable improvement after DBS.Owing to its minimally invasive nature,reversibility,and adjustability,DBS has been increasingly used over the past several decades.Dystonia is one of the most common movement disorders among children,and there is no effective treatment.Recently,some surgeon groups have performed DBS surgery for children.However,the outcomes of DBS in children are not well characterized.Here we mainly discuss the efficacy of DBS against childhood-onset dystonia and introduce the main procedure of pediatric DBS based on our own experience.

Facile construction of Zn(Ⅱ)-porphyrin-cored [5]rotaxane and its controllable aggregation behaviours

Rotaxanes have attracted more and more attentions because of their diverse applications as sensors,catalysts, and functional materials. The construction of highly ordered and discrete multirotaxanes with the well-defined structure remains a challenge. Herein, a symmetric [5]rotaxane with zinc porphyrin as core and the neutral platinum-acetylide as the linkage was synthesized with high yield. The [5]rotaxane was well characterized with NMR spectroscopy and MALDI-TOF mass spectrometry. Interestingly, it was found that the [5]rotaxane showed the controllable aggregation behaviours in different solution compositions. For example, in non-polar solution, the [5]rotaxane could self-assemble into the largescaled solid nanospheres while the nanofibers were formed in polar solvent. Further investigation revealed that the [5]rotaxane displayed J-type aggregation in solution driven by p-p interaction. Notably,the similar structure without DPP[5]A formed the irregular morphology at the same condition,suggesting that the existence of rotaxanes endowed the complex with a relative rigid structure to facilitate the formation of the ordered aggregates.