不同围压三轴循环压缩下岩石的线性储能和耗能规律及损伤演化特征

为了研究岩石的能量分布规律及其围压效应,开展不同围压下的三轴循环压缩试验。基于所得应力-应变曲线计算不同应力水平下的峰前输入应变能、峰前弹性应变能和峰前耗散应变能。结果表明,不同围压下峰前弹性应变能和峰前耗散应变能与峰前输入应变能呈明显线性相关,从而得到三轴循环压缩下的线性储能和耗能规律。岩石三轴压缩储能系数与围压呈正相关,而对应的耗能系数则相反。利用线性储能规律,可以推导出岩石在三轴压缩作用下的峰值弹性应变能和峰值耗散应变能。此外,基于线性耗能规律分析了不同围压下岩石的损伤演化特征。

Detailed sedimentary structure of the Mianning segment of the Anninghe fault zone revealed by H/V spectral ratio

The Anninghe fault is a major left-lateral strike-slip fault in southwest China and a seismic gap with a potential earthquake larger than MW 7.0 lies in the Mianning-Xichang segment according to recent observations.The shallow structure of this region can offer a glimpse into the geometry of the fault,which plays an important role in earthquake hazard mitigation.To further investigate the sedimentary structure of the Anninghe fault zone,two dense linear arrays with a station spacing of around 80 m were deployed across the fault.In this study,the H/V spectral ratio(HVSR),together with its peak frequency at each station site,was obtained by applying the Nakamura method.Our findings demonstrate that the peak frequency behaves in high correlation with lithology and is controlled by topography.HVSR in foothills or regions with magmatic intrusion shows a single peak at about 2–3 Hz.In locations with abundant Quaternary sedimentation,such as Anninghe valleys and fracture zones,another low-frequency peak around 0.4 Hz can be noticed in HVSR.By using the empirical relationship,the thickness of the sedimentary layer around the fault fracture zone is estimated to be 300–600 m.Furthermore,the sedimentary interface shows a downward dip to the east,possibly influenced by the east-west extrusion stress.Considering the resonance effect,buildings with 6–9 stories in the valley area of the Anninghe require additional attention in earthquake hazard prevention.

Systematic study on the proton radioactivity of spherical proton emitters

In this study, based on a two-potential approach, we systematically investigated the proton radioactivity half-lives of spherical proton emitters with 69≤Z≤81 from the ground and/or isomeric state, choosing the nuclear potential to be a modified Woods–Saxon potential that contains the isospin effect of the daughter nucleus. It was found that the calculated half-lives could reproduce the experimental data well. Furthermore, we extended this model to predict the half-lives of 17 protonemitting candidates whose radioactivity is energetically allowed or observed but not yet quantified in NUBASE2020. For comparison, the unified fission model, Coulomb potential and proximity potential model, universal decay law for proton emission, and new Geiger–Nuttall law were also used. All the predicted results are consistent with each other.

A palaeoearthquake event and its age revealed by the travertine layer along the Litang fault in the southeastern margin of the Qinghai-Tibetan plateau

The Litang fault(LTF),located in the southeast of the Qinghai-Tibetan Plateau,is known for its high level of present-day seismicity,whereas its Pleistocene activity has been scarcely documented.This study focused on a tract of banded travertine deposits precipitated from thermal waters along the NW–SE-trending LTF trace.The role of travertine deposits in recording neotectonic activity has been studied by identifying their internal structure.Typical soft-sediment deformation structures observed within the banded travertines include micro folds,liquefied breccia,and liquefied diapirs.These deformed structures,which are restricted to a single unit separated unconformably by undeformed layers,can be traced for tens of meters,indicating that they were formed by seismic shaking triggered by LTF activity.The deformation of the banded travertine layers is attributed to the combined effects of seismic shaking,liquefaction,and fluidization,and it can be related to a paleo earthquake event with a magnitude of MS>5.The U-series ages obtained from the banded travertine deposits perturbed by the earthquakes are in the range of 130.59–112.94 ka,indicating an important fault-assisted neotectonic activity that occurred during the Middle–Late Pleistocene.Analysis of such structures,in combination with the use of U-series dating methods,can yield a reliable timing of neotectonic activity and provide new evidence for under-standing the seismotectonic setting of the Litang area.

甲型流感病毒突变诱发的神经氨酸酶耐药性机制理论研究

甲型流感(A/HxNy)因其高传染性和高死亡率严重威胁人类健康、危害人类公共卫生安全面受到广泛关注.神经氨酸酶(NA)通过靶向宿主细胞中的唾液酸(SIA)并与之相互作用进而达到释放子代病毒的目的.由于其高度保守的催化中心结构,已成为药物设计的重要目标.临床上已经出现了各种耐药的神经氨酸酶突变株,本工作对A/H7N9(N9亚型)由突变引发的耐药机制进行了详细探究.通过分子动力学模拟和丙氨酸突变扫描结合相互作用熵方法来探索R294K突变前后N9和药物扎那米韦结合机制的差异.研究结果表明,突变导致Arg294和Z药物扎那米韦之间的氢键断裂,并破坏了结合口袋附近热点残基与药物间的氢键网络,从而导致药物对N9的结合能力减弱,产生耐药性.同时,来自A/H11N9的N9野生型与R292K突变型也被用于研究耐药性产生的机制.预测的突变前后N9与5种抑制剂(SIA、DAN、药物扎那米韦、G28和G39)结合自由能的不同与实验值基本一致,验证了丙氨酸突变扫描结合相互作用熵方法用于本工作的可靠性.此外,对关键残基的分析表明Arg292、Tyr406在野生型A/H11N9与药物的相互作用中表现为热点氨基酸.然而,在突变型A/H11N9中,292残基对结合自由能没有明显有利的贡献,这可能会增强突变植株的抗药性.相比之下,当SIA、药物扎那米韦和G28与突变型A/H11N9作用时,Tyr406仍保留热点残基的特征.结合以上两组甲型流感病毒(N9亚型)的动力学模拟研究,推测了病毒抗药性主要是由氢键网络的破坏和热点的转变引起的.该研究可以为治疗甲型流感(N9亚型)耐药突变的新型药物开发和药物优化提供理论指导.

A new criterion of coal burst proneness based on the residual elastic energy index

To evaluate the coal burst proneness more precisely,a new energy criterion namely the residual elastic energy index was proposed.This study begins by performing the single-cyclic loading-unloading uniaxial compression tests with five pre-peak unloading stress levels to explore the energy storage characteristics of coal.Five types of coals from different mines were tested,and the instantaneous destruction process of the coal specimens under compression loading was recorded using a high speed camera.The results showed a linear relationship between the elastic strain energy density and input energy density,which confirms the linear energy storage law of coal.Based on this linear energy storage law,the peak elastic strain energy density of each coal specimen was obtained precisely.Subsequently,a new energy criterion of coal burst proneness was established,which was called the residual elastic energy index(defined as the difference between the peak elastic strain energy density and post peak failure energy density).Considering the destruction process and actual failure characteristics of coal specimens,the accuracy of evaluating coal burst proneness based on the residual elastic energy index was examined.The results indicated that the residual elastic energy index enables reliable and precise evaluations of the coal burst proneness.

3-D shear wave velocity structure in the shallow crust of the Tan-Lu fault zone in Lujiang,Anhui,and adjacent areas,and its tectonic implications

The Tan-Lu fault zone is a large NNE-trending fault zone in eastern China.Investigations of the structures of the fault zone and its surrounding areas have attracted much attention.In this study,we used dense-array ambient noise tomography to construct a threedimensional shear wave velocity model of shallow crust in an area about 80km×70km in Lujiang,Anhui Province,eastern China.For approximately one month we collected continuous ambient noise signals recorded by 90 short-period seismographs in the region,and obtained the short-period Rayleigh wave empirical Green's functions between stations by the cross-correlation method;we also extracted 0.5–8 s fundamental mode Rayleigh wave group velocity and phase velocity dispersion curves.Based on the direct surface wave tomography method,we jointly inverted the group velocity and phase velocity dispersion data of all paths and obtained the 3-D shear wave velocity structure in the depth range of 0–5 km.The results revealed important geological structural features of the study area.In the north region,the sedimentary center of the Hefei Basin—the southwestern part of the Chaohu Lake—shows a significant low-velocity anomaly to a depth of at least 5 km.The southwestern and southeastern regions of the array are the eastern margin of the Dabie orogenic belt and the intrusion area of Luzong volcanic rocks,respectively,and both show obvious high-speed anomalies;the sedimentary area within the Tan-Lu fault zone(about 10 km wide)shows low-velocity anomalies.However,the volcanic rock intrusion area in the fault zone is shown as high velocity.Our shallow crustal imaging results reflect the characteristics of different structures in the study area,especially the high-speed intrusive rocks in the Tan-Lu fault zone,which were probably partially derived from the magmatic activity of Luzong volcanic basin.From the Late Cretaceous to Early Tertiary,the Tan-Lu fault zone was in a period of extensional activity;the special stress environment and the fractured fault zone morphology provided conditions for magma in the Luzong volcanic basin to intrude into the Tan-Lu fault zone in the west.Our 3-D model can also provide important information for deep resource exploration and earthquake strong ground motion simulation.

Theoretical verification of the rationality of strain energy storage index as rockburst criterion based on linear energy storage law

The rationality of using strain energy storage index(Wet)for evaluating rockburst proneness was theoretically verified based on linear energy storage(LES)law in this study.The LES law is defined as the linear relationship between the elastic strain energy stored inside the solid material and the input strain energy during loading.It is used to determine the elastic strain energy and dissipated strain energy of rock specimens at various loading/unloading stress levels.The results showed that the Wetvalue obtained from experiments was close to the corresponding theoretical one from the LES law.Furthermore,with an increase in the loading/unloading stress level,the ratio of elastic strain energy to dissipated strain energy converged to the peak-strength strain energy storage index(Wp et).This index is stable and can better reflect the relative magnitudes of the stored energy and the dissipated energy of rocks at the whole pre-peak stage than the strain energy storage index.The peak-strength strain energy storage index can replace the conventional strain energy storage index as a new index for evaluating rockburst proneness.

Preparation and Property Analysis of Melamine Formaldehyde Foam

Melamine formaldehyde (MF) foam is kind of fire-retardant material and has great potential in acoustic and thermal insulation area. In this article, MF resin foam was prepared by microwave radiation. We discussed the thermal stability of MF foam and the effect of different emulsifiers on its morphology, apparent density, fire-retardancy and mechanical property. The decomposition temperature of MF foam we prepared is nearly 400℃ and the constitution of residue after combustion is made up of carbon and graphite. Emulsifier influenced the apparent density of MF foam and using coemulsifiers can get flexible foam with uniform cell size, good morphology and low apparent density. When the fire-retardant MF foam’s apparent density is low of 5.53 kg/cm-3, its value of LOI can reach 32.4. The mechanical property of foam is consistent with apparent density.

Polariton lasing in InGaN quantum wells at room temperature

In this paper,we report the exciton polaritons in both positive and negative detuning micro cavities based on InGaN multi-quantum wells(MQWs)and the first polariton lasing in InGaN/GaN MQWs at room temperature by utilizing a 4.5λFabry-Perot(F-P)cavity with double dielectric distributed Bragg reflectors(DBRs).Double thresholds corresponding respectively to polariton lasing and photonic lasing are observed along with half-width narrowing and peak blue-shifts.The threshold of polariton lasing is about half of the threshold of photonic lasing.Our results paved a substantial way for ultra-low threshold lasers and room temperature Bose-Einstein Condensate(BEC)in nitride semiconductors.

矿用对旋风机噪声识别技术研究

针对目前矿用对旋轴流局部通风机噪声较高问题,对风机噪声进行了测试,利用频谱分析技术对噪声进行识别。结果表明:对旋风机的噪声主要由气动噪声构成,噪声尖峰主要表现为I、II级叶轮旋转噪声、干扰噪声及其高次谐波噪声。涡流噪声随着载荷的增加而增大,低频噪声随载荷增加变化不明显,高频噪声随载荷增加而增大。

P-wave velocity structure in the crust and the uppermost mantle of Chao Lake region of the Tan-Lu Fault inferred from teleseismic arrival time tomography

Chao Lake is a Geoheritage site on the active Tan-Lu Fault between the Yangtze craton,the North China craton,and the Dabie orogenic belt in the southeast.This segment of the fault is not well constrained at depth partly due to the overprinting of the fault zone by intrusive materials and its relatively low seismic activity and sparse seismic station coverage.This study took advantage of a dense seismic array deployed around Chao Lake to delineate the P-wave velocity variations in the crust and uppermost mantle using teleseismic earthquake arrival time tomography.The station-pair double-difference with waveform crosscorrelation technique was employed.We used a multiscale resolution 3-D initial model derived from the combination of highresolution 3-D v S models within the region of interest to account for the lateral heterogeneity in the upper crust.The results revealed that the velocity of the upper crust is segmented with structures trending in the direction of the strike of the fault.Sedimentary basins are delineated on both sides of the fault with slow velocities,while the fault zone is characterized by high velocity in the crust and uppermost mantle.The high-velocity structure in the fault zone shows characteristics of magma intrusion that may be connected to the Mesozoic magmatism in and around the Middle and Lower Yangtze River Metallogenic Belt(MLYMB),implying that the Tan-Lu fault might have formed a channel for magma intrusion.Magmatic material in Chao Lake is likely connected to the partial melting,assimilation,storage,and homogenization of the uppermost mantle and the lower crustal rocks.The intrusions,however,seem to have suffered severe regional extension along the Tan-Lu fault driven by the eastward Paleo-Pacific plate subduction,thereby losing its deep trail due to extensional erosion.

A multi-scale 3-D crust velocity model in the Hefei-Chao Lake area around the southern segment of Tanlu Fault Zone

Regional high-precision velocity models of the crust are an important foundation for examining seismic activity,seismogenic environments,and disaster distribution characteristics.The Hefei-Chao Lake area contains the main geological units of Hefei Basin,with thick sediments and the Chao Lake depression.Several major concealed faults of the southern NNE-trending Tanlu Fault Zone cross this area.To further explore the underground distribution characteristics of the faults and their tectonic evolutionary relationship with adjacent tectonic units,this study used ambient noise data recorded by a seismic array deployed in Hefei City and Chao Lake,constructing a 3-D velocity model at the depth of 1–8 km.Then a multi-scale high-resolution 3-D velocity model of this area was constructed by this new upper crustal velocity model with the previous middle and lower crustal model.The new model reveals that a high-velocity belt is highly consistent with the strike of the Tanlu Fault Zone,and a low-velocity sedimentary characteristic is consistent with the Hefei Basin and Chao Lake depression.The distribution morphology of high and low velocity bodies shows that the sedimentary pattern of Hefei-Chao Lake area is closely related to the tectonic evolution of the Tanlu Fault Zone since the Mesozoic.This study also identifies multiple low-velocity anomalies in the southeastern Hefei City.We speculate that strong ground motion during the 2009 Feidong earthquake(magnitude of 3.5)was related to amplification by the thick sediments in the Hefei Basin.We also discuss further applications of multi-scale high-resolution models of the shallow layer to strong ground motion simulations in cities and for earthquake disaster assessments.

铝合金模板配板设计技术

近年来,我国建筑行业实施了工业化改革与产业转型,扩大了新材料、新技术、新工艺的应用,较好地提升了生产效率与施工质量。当前正值“十四五”时期高质量发展阶段,需要结合前期实践经验,进一步增加此类要素的配置,为建筑工程生产建设赋能。以此为出发点,概述了铝合金模板配板设计的重要性,分别从降低增效、降低非标板占比、高质量配板设计3个层面对其相关设计技术进行具体讨论。

Large-scale control of enhancement and quenching of photoluminescence for ZnSe/ZnS quantum dots and Ag nanoparticles in aqueous solution

We investigated the optical properties of hybrid exciton–plasmon coupling ensembles composed of ZnSe/ZnS quantum dots and Ag nanoparticles in aqueous solution. We modulated their average interval by changing the ratio of quantum dots and Ag nanoparticles. The transition from dramatic PL enhancement to PL quenching state was experimentally observed, according to the continuous decrease of the PL lifetime. The PL enhancement rate exceeded 10, with the Purcell factor of 3.5. Meanwhile, the proportion of fast decay increased from 0.3 to 0.6, corresponding to the proportion of slow decay decreased from 0.7 to 0.4. Our experiment is important for the hybrid exciton–plasmon coupling system to be practicable in optoelectronic application.

Evaluation of rockburst proneness considering specimen shape by storable elastic strain energy

To systematically assess the rockburst proneness considering specimen shape,multiple groups of laboratory tests were performed on 5 rock materials in cylindrical and cuboid shapes.The linear energy storage(LES)law of both cylindrical and cuboid rock specimens under uniaxial compressive load was confirmed,and the energy storage coefficient was found to be unrelated to specimen shape.On the basis of LES law,two rockburst proneness indexes,namely the strain energy storage index(W_(et))and the potential energy of elastic strain(PES),were modified.Subsequently,the W_(et),PES,peak-strength strain energy storage index(W_(et))p,and peak-strength potential energy of elastic strain(PESp)were used to assess the rockburst proneness of the cylindrical and cuboid specimens.In addition,the fragment ejection course of specimens under test was recorded by a high-speed camera.Then,the rockburst proneness judgments obtained from the 4 indexes were compared with the qualitative data during rock destruction.The results show that,under similar stress conditions,specimen shape has an ignorable effect on the rockburst proneness as a whole.The judgment accuracy of the two modified indexes,especially that of the PESp,is favorably improved to evaluate the rockburst proneness of both cylindrical and cuboid specimens.However,misjudgment ofW_(et)^(p)and PESp may still occur in the assessment of rockburst proneness as these two indexes only consider the energy state before rock peak strength and the W_(et)^(p)is formulated in a ratio form.

Influence of self-similar stresses on scenario earthquake construction:An example along the Tanlu Fault

As a famous deep and large fault in eastern China,the Tanlu Fault passes through Anhui,Jiangsu,and Shandong and into northeastern China.It is important to improve the understanding of seismic hazard assessments in areas near faults.We start a scenario earthquake simulation in the M7.5 earthquake potential area of the Xinyi-Sihong segment of the Tanlu Fault.The fault rupture length and width are constrained according to the scaling law of large intraplate earthquakes,the background normal stress is depth dependent,and the initial shear stresses are determined using trial and error by matching the earthquake magnitude.Considering the 120 km rupture length of the M7.5 earthquake,we compare the horizontal uniform stress model and self-similar stress perturbation model.Our findings reveal that the seismic source time function of the horizontal uniform stress model is similar to that of the Haskell model and that of the self-similar stress perturbation model is more similar to that of a real earthquake case.We compare the dynamic rupture simulation and ground motion results under four different stress conditions and find that the shorter the characteristic length of the self-similar function is,the rougher the initial stress.For the M7.5earthquake with an epicenter in the vicinity of Suqian,the Xinyi-Tancheng segment,which is located in the IX-intensity zone north of the epicenter,vibrates more strongly on the northern side than on the southern side due to the influence of the lowvelocity zone and the peak slip rate.The response spectra analysis at stations in the study area is useful for improving the earthquake resistance capability.

α-particle preformation factors in heavy and superheavy nuclei

In this study,α-particle preformation factors in heavy and superheavy nuclei from ^(220)Th to ^(294)Og are investigated.By combing experimental α decay energies and half-lives,the α-particle preformation factors P_(α) are extracted from the ratios between theoretical α decay half-lives calculated using the Two-Potential Approach (TPA)and experimental data.We find that the α-particle preformation factors exhibit a noticeable odd-even staggering behavior,and unpaired nucleons inhibit α-particle preformation.Moreover,we find that both the α decay energy and mass number of parent nucleus exhibit considerable regularity with the extracted experimental α-particle preformation factors.After considering the major physical factors,we propose a local phenomenological formula with only five valid parameters for α-particle preformation factors P_(α).This analytic expression has a clear physical meaning as well as good precision.As an application,this analytic formula is extended to estimate the α-particle preformation factors and further predict the α decay half-lives for unknown even-even nuclei with Z=118 and 120.

Edge reconstruction of layer-dependentβ-In2Se3/MoS2 vertical heterostructures for accelerated hydrogen evolution

The layer-dependent properties are still unclarified in two-dimensional(2D)vertical heterostructures.In this study,we layer-bylayer deposited semimetalβ-In2Se3 on monolayer MoS2 to form verticalβ-In2Se3/MoS2 heterostructures by chemical vapor deposition.The defect-mediated nucleation mechanism inducesβ-In2Se3 nanosheets to grow on monolayer MoS2,and the layer number of stackedβ-In2Se3 can be precisely regulated from 1 layer(L)to 13 L by prolonging the growth time.Theβ-In2Se3/MoS2 heterostructures reveal tunable type-Ⅱband alignment arrangement by altering the layer number ofβ-In2Se3,which optimizes the internal electron transfer.Meanwhile,the edge atomic structure ofβ-In2Se3 stacking on monolayer MoS2 shows the reconstruction derived from large lattice mismatch(~29%),and the presence ofβ-In2Se3 also further increases the electrical conductivity ofβ-In2Se3/MoS2 heterostructures.Attributed to abundant layer-dependent edge active sites,edge reconstruction,improved hydrophilicity,and high electrical conductivity ofβ-In2Se3/MoS2 heterostructures,the edge ofβ-In2Se3/MoS2 heterostructures exhibits excellent electrocatalytic hydrogen evolution performance.Lower onset potential and smaller Tafel slope can be observed at the edge of monolayer MoS2 coupled with 13-Lβ-In2Se3.Hence,the outstanding conductive layers coupled with edge reconstruction in 2D vertical heterostructures play decisive roles in the optimization of electron energy levels and improvement of layer-dependent catalytic performance.

Simple model for cluster radioactivity half-lives in trans-lead nuclei

In this study,considering the modified preformation probability P_(c)to be log_(10)P_(c)=(A_(c)−1)/3log_(10)P_(α)+c′,where P_(α)and c′are theα-particle preformation probability and an adjustable parameter proposed by Wang et al.[Chin.Phys.C 45,044111(2021)],respectively,we extend a new simple model put forward by Bayrak[J.Phys.G 47,025102(2020)]to systematically study the cluster radioactivity half-lives of 28 trans-lead nuclei ranging from^(222)Fr to^(242)Cm,which is based on the Wentzel-Kramers-Brillouin approximation and Bohr–Sommerfeld quantization condition.For comparison,a universal decay law proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a three-parameter model-independent formula put forward by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and the semi-empirical model proposed by Tavares et al.[Eur.Phys.J.A 49,1(2013)]are used.Our calculated results reproduce the experimental data well,with a standard deviation of 0.818.Furthermore,we use this model to predict the cluster radioactivity half-lives of 51 possible cluster radioactive candidates whose cluster radioactivities are energetically allowed or observed but not yet quantified in NUBASE2020.