Beam based alignment using a neural network

Beams typically do not travel through the magnet centers because of errors in storage rings.The beam deviating from the quadrupole centers is affected by additional dipole fields due to magnetic field feed-down.Beam-based alignment(BBA)is often performed to determine a golden orbit where the beam circulates around the quadrupole center axes.For storage rings with many quadrupoles,the conventional BBA procedure is time-consuming,particularly in the commissioning phase,because of the necessary iterative process.In addition,the conventional BBA method can be affected by strong coupling and the nonlinearity of the storage ring optics.In this study,a novel method based on a neural network was proposed to determine the golden orbit in a much shorter time with reasonable accuracy.This golden orbit can be used directly for operation or adopted as a starting point for conventional BBA.The method was demonstrated in the HLS-II storage ring for the first time through simulations and online experiments.The results of the experiments showed that the golden orbit obtained using this new method was consistent with that obtained using the conventional BBA.The development of this new method and the corresponding experiments are reported in this paper.

Cascade adsorptive separation of light hydrocarbons by commercial zeolites

Adsorptive separation of light hydrocarbons by porous solids provides an energy-efficient alternative to state-of-the-art cryogenic distillation.However,an optimal balance between the cost,performance and stability of the sorbent material is yet to be achieved for industrial applications.Here,we report the efficient separation of C2 and C3 hydrocarbons by a faujasite zeolite(Na-X,Si/Al=1.23).A tandem configuration of two fixed-beds packed with Na-X affords complete dynamic separation of the ternary mixture of C_(2)H_(2)/C_(2)H_(4)/C_(2)H_(6)(1/49.5/49.5;v/v/v)under ambient conditions.Pressure-swing desorption on the latter fixed-bed gives ethylene(>99.50%,1.80 mmol g^(-1))and ethane(>99.99%,1.41 mmol g^(-1)).In situ synchrotron X-ray powder diffraction revealed the binding sites for C_(2)H_(2)and C_(2)H_(4)in Na-X.This study highlights the potential application of commercial zeolites for challenging industrial separations.

超声处理对Al-0.4Zr合金中生成的初生Al_3Zr金属间化合物的影响（英文）

通过在Al-0.4Zr合金凝固过程中外加超声场研究超声处理对Al_3Zr金属间化合物形成的影响。超声处理分别采用在凝固过程中的3个温度区间:830~790°C(高于液相线)、790~750°C(横跨液相线)和750~710°C(低于液相线)。超声处理后利用扫描电子显微镜对铸态合金中生成的Al_3Zr金属间化合物的尺寸和形貌进行分析观测。结果显示,超声处理后Al_3Zr金属间化合物的尺寸显著减小而且形貌也从流星镖状转变成细小片状。讨论Al_3Zr金属间化合物超声细化机理。结果表明,超声处理高于液相线时形成的细化效果主要是由于空化气泡激发氧化铝颗粒成为Al_3Zr金属间化合物形核质点从而提高形核率;超声处理低于液相线时形成的细化效果主要是由于空化气泡打断生长中的Al_3Zr金属间化合物。

A Superconducting Magnet with Center Field of 10 T and φ100 mm Warm Bore

Aconduction-cooled superconducting magnet with central field of 10Tand warmbore of 100 mmwas designed based on a Nb3Sn and two NbTi superconducting coils.At the first stage,the NbTi coils havebeen fabricated andtested.Atwo-stage 4 KGifford-McMahon(GM) cryocooler withthe second-stage powerin1W,4.2Kis used to cool the magnet fromroomtemperature to 4 K.The superconducting magnet with thesame power supply has the operating current of 116A.The magnet can be rotated with a support frame to beoperated with either horizontal or vertical position.Apair of Bi-2223 hightemperature superconductingcurrentleads was employedto reduce heat leakage into 4.2Klevel.The NbTi coils reachto the operating current of120Awithout training effect to be observed duringchargingof the magnet during40 minutes chargingtime andgenerate the center field of 6.5T.The training effect inthe NbTi magnet directly cool-down by cryocooler andinter-winding support structure in magnet can be remarkablyimproved.The superconducting magnet has beenstably operatedfor more than 275 hours with 6.5T.In this paper,the detailed design,fabrication,stressanalysis and quench protection characteristics are presented.

Monitoring dynamics of defects and single Fe atoms in N-functionalized few-layer graphene by in situ temperature programmed scanning transmission electron microscopy

In this study,we aim to contribute an understanding of the pathway of formation of Fe species during top-down synthesis of dispersed Fe on N-functionalized few layer graphene,widely used in electrocatalysis.We use X-ray absorption spectroscopy to determine the electronic structure and coordination geometry of the Fe species and in situ high angle annular dark field scanning transmission electron microscopy combined with atomic resolved electron energy loss spectroscopy to localize these,identify their chemical configuration and monitor their dynamics during thermal annealing.We show the high mobility of peripheral Fe atoms,first diffusing rapidly at the trims of the graphene layers and at temperatures as high as 573 K,diffusing from the edge planes towards in-plane locations of the graphene layers forming three-,four-coordinated metal sites and more complexes polynuclear Fe species.This process occurs via bond C-C breaking which partially reduces the extension of the graphene domains.However,the vast majority of Fe is segregated as a metal phase.This dynamic interconversion depends on the structural details of the surrounding graphitic environment in which these are formed as well as the Fe loading.N species appear stabilizing isolated and polynuclear Fe species even at temperatures as high as 873 K.The significance of our results lies on the fact that single Fe atoms in graphene are highly mobile and therefore a structural description of the electroactive sites as such is insufficient and more complex species might be more relevant,especially in the case of multielectron transfer reactions.Here we provide the experimental evidence of the formation of these polynuclear Fe-N sites and their structural characteristics.

Corrigendum to“Monitoring dynamics of defects and single Fe atoms in N-functionalized few-layer graphene by in situ temperature programmed scanning transmission electron microscopy”[JECHEM 64(2022)520-530]

The authors regret that the word“trim/trims”has been wrongly used in the overall text,and instead the correct word“edge/edges”should have been used.The authors would like to apologise for any inconvenience caused.

Observation of Fermi Arcs in Non-Centrosymmetric Weyl Semi-Metal Candidate NbP

We report the surface electronic structure of niobium phosphide NbP single crystal on （001） surface by vacuum ultraviolet angle-resolved photoemission spectroscopy. Combining with our first principle calculations, we identify the existence of the Fermi arcs originated from topological surface states. Furthermore, the surface states exhibit circular dichroism pattern, which may correlate with its non-trivial spin texture. Our results provide critical evidence for the existence of the Weyl Fermions in NbP, which lays the foundation for further research.

Observation of a single protein by ultrafast X-ray diffraction

The idea of using ultrashort X-ray pulses to obtain images of single proteins frozen in time has fascinated and inspired many.It was one of the arguments for building X-ray free-electron lasers.According to theory,the extremely intense pulses provide sufficient signal to dispense with using crystals as an amplifier,and the ultrashort pulse duration permits capturing the diffraction data before the sample inevitably explodes.This was first demonstrated on biological samples a decade ago on the giant mimivirus.Since then,a large collaboration has been pushing the limit of the smallest sample that can be imaged.The ability to capture snapshots on the timescale of atomic vibrations,while keeping the sample at room temperature,may allow probing the entire conformational phase space of macromolecules.Here we show the first observation of an X-ray diffraction pattern from a single protein,that of Escherichia coli GroEL which at 14 nm in diameter is the smallest biological sample ever imaged by X-rays,and demonstrate that the concept of diffraction before destruction extends to single proteins.From the pattern,it is possible to determine the approximate orientation of the protein.Our experiment demonstrates the feasibility of ultrafast imaging of single proteins,opening the way to single-molecule time-resolved studies on the femtosecond timescale.

4^(th) generation synchrotron source boosts crystalline imaging at the nanoscale

New 4^(th)-generation synchrotron sources,with their increased bilince,promise to greatly improve the performances of coherent X-ray microscopy.This perspective is of major interest for crystal microscopy,which aims at revealing the 3D crystalline structure of matter at the nanoscale,an approach strongly limited by the available coherent flux.Our results,based on Bragg ptychography experiments performed at the frst 4-generation synchrotron source,demonstrate the possibility of retrieving a high-quality image of the crystalline sample,with unprecedented quality.Importantly,the larger available coherent flux produces datasets with enough information to overcome experimental limitations,such as strongly deteriorated scanning conditions.We show this achievement would not be posible with 30-generation sources,a limit that has inhibited the development of this otherwise powerful microscopy method,so far.Hence,the advent of next-generation synchrotron sources not only makes Bragg ptychography suitable for high throughput studies but also strongly relaxes the associated experimental constraints,making it compatible with a wider range of experimental set-ups at the new synchrotrons.

CD44 and CD221 directed magnetic cubosomes for the targeted delivery of helenalin to rhabdomyosarcoma cells

Confining chemotherapy to tumour sites by means of active targeting nanoparticles(NPs)may increase the treatment effectuality while reducing potential side effects.Cubosomes are one of the next-generation drug delivery nanocarriers by virtue of their biocompatibility and bioadhesion,sizeable payload encapsulation and high thermostability.Herein,an active tumour targeting system towards rhabdomyosarcoma(RMS)cells was evaluated.Cubosomes were loaded with helenalin(a secondary metabolite from Arnica plants),which we have previously shown to induce apoptosis in RMS cells.The functionalization of the cubosomes was accomplished to enable binding to membrane receptors and translocation under a magnetic field.RMS cells overexpress CD44 and CD221 on their membrane surface and,therefore,hyaluronic acid(HA,a ligand for CD44)and antibodies(Abs)against CD221 were coupled to cubosomes via electrostatic attraction and the thiol-Michael reaction,respectively.Magnetization of the cubic phase NPs was achieved by embedding superparamagnetic iron oxide NPs(SPIONPs)into the cubic matrix.Single-function and multi-function cubosomes had Im3m cubic phase structures with well-organized lattice patterns.Conjugation with 2%HA or anti-CD221 half Abs and/or 1%SPIONPs showed significantly higher uptake into RMS cells compared to unfunctionalized cubosomes.CD44 and CD221 directed magnetic(triple-function)cubosomes were capable of internalizing into RMS cells in an energy-independent mechanism.Helenalin-laden triple functionalized cubosomes showed limited impact on the viability of control fibroblast cells,while they induced a high degree cytotoxicity against RMS cells.Profound tumour cell death was observed in both two-dimensional(2D)culture and three-dimensional(3D)tumour spheroids.

Versatile domain mapping of scanning electron nanobeam diffraction datasets utilising variational autoencoders

Characterisation of structure across the nanometre scale is key to bridging the gap between the local atomic environment and macro-scale and can be achieved by means of scanning electron nanobeam diffraction(SEND).As a technique,SEND allows for a broad range of samples,due to being relatively tolerant of specimen thickness with low electron dosage.This,coupled with the capacity for automation of data collection over wide areas,allows for statistically representative probing of the microstructure.This paper outlines a versatile,data-driven approach for producing domain maps,and a statistical approach for assessing their applicability.The workflow utilises a Variational AutoEncoder to identify the sources of variance in the diffraction signal,and this,in combination with clustering techniques,is used to produce domain maps.This approach is agnostic to domain crystallinity,requires no prior knowledge of crystal structure,and does not require simulation of a library of expected diffraction patterns.

nNPipe: a neural network pipeline for automated analysis of morphologically diverse catalyst systems

We describe nNPipe for the automated analysis of morphologically diverse catalyst materials. Automated imaging routines anddirect-electron detectors have enabled the collection of large data stacks over a wide range of sample positions at high temporalresolution. Simultaneously, traditional image analysis approaches are slow and hence unsuitable for large data stacks andconsequently, researchers have progressively turned towards machine learning and deep learning approaches. Previous studiesoften detail work on morphologically uniform material systems with clearly discernible features, limited workable image sizes andtraining data that may be biased due to manual labelling. The nNPipe data-processing method consists of two standaloneconvolutional neural networks that were exclusively trained on multislice image simulations and enables fast analysis of2048 × 2048 pixel images. Inference performance compared between idealised and real industrial catalytic samples and insightsderived from subsequent data analysis are placed into the context of an automated imaging scenario.

High-throughput calculations of charged point defect properties with semi-local density functional theory— performance benchmarks for materials screening applications

Calculations of point defect energetics with Density Functional Theory(DFT)can provide valuable insight into several optoelectronic,thermodynamic,and kinetic properties.These calculations commonly use methods ranging from semi-local functionals with a-posteriori corrections to more computationally intensive hybrid functional approaches.For applications of DFT-based high-throughput computation for data-driven materials discovery,point defect properties are of interest,yet are currently excluded from available materials databases.This work presents a benchmark analysis of automated,semi-local point defect calculations with a-posteriori corrections,compared to 245“gold standard”hybrid calculations previously published.We consider three different a-posteriori correction sets implemented in an automated workflow,and evaluate the qualitative and quantitative differences among four different categories of defect information:thermodynamic transition levels,formation energies,Fermi levels,and dopability limits.We highlight qualitative information that can be extracted from high-throughput calculations based on semi-local DFT methods,while also demonstrating the limits of quantitative accuracy.

高温合金差示扫描量热分析(DSC)的影响因素:粉末粒度和显微组织

对固溶强化型625镍基高温合金粉末进行升、降温差示扫描量热分析(DSC)试验,研究了不同粉末粒度(<37,45~53,75~105,105~150,150~355μm)对相变温度的影响。采用场发射扫描电镜(FESEM)、电子探针(EPMA)和同步辐射X射线衍射(SXRD)对625合金粉末的形貌、元素分布和相组成进行表征。结果表明:不同粒径PM625粉末均为树枝晶结构,枝晶间距在2~10μm范围,元素Ni和Cr倾向分布于枝晶干,Mo和Nb偏析于枝晶间。不同粒度的PM625粉末中均仅存在基体γ相。PM625粉末DSC加热曲线固相线附近区域拐点尖锐,表现为合金开始熔化温度(偏离基线的拐点)与名义固相线温度(切线交点)差异很小,不同粒度间的差异仅为2~5℃。合金完全熔化后重新冷却的过程中原始粉末的低偏析特性消失,冷却曲线固相线区域圆弧较大,名义固相线和终凝温度差较大,为53~65℃。DSC试验升温过程中不同粒径粉末的固、液相线以及初熔温度最大差异分别为3, 2和2℃,降温过程不同粒径粉末固、液相线温度差分别为6和2℃。0~355μm粉末粒径范围内,粒径对固溶强化型PM625高温合金粉末相变温度无明显影响。

Nano-precision metrology of X-ray mirrors with laser speckle angular measurement

X-ray mirrors are widely used for synchrotron radiation,free-electron lasers,and astronomical telescopes.The short wavelength and grazing incidence impose strict limits on the permissible slope error.Advanced polishing techniques have already produced mirrors with slope errors below 50 nrad root mean square(rms),but existing metrology techniques struggle to measure them.Here,we describe a laser speckle angular measurement(SAM)approach to overcome such limitations.We also demonstrate that the angular precision of slope error measurements can be pushed down to 20nrad rms by utilizing an advanced sub-pixel tracking algorithm.Furthermore,SAM allows the measurement of mirrors in two dimensions with radii of curvature as low as a few hundred millimeters.Importantly,the instrument based on SAM is compact,low-cost,and easy to integrate with most other existing X-ray mirror metrology instruments,such as the long trace profiler(LTP)and nanometer optical metrology(NOM).The proposed nanometrology method represents an important milestone and potentially opens up new possibilities to develop next-generation super-polished X-ray mirrors,which will advance the development of X-ray nanoprobes,coherence preservation,and astronomical physics.

A deep convolutional neural network for real-time full profile analysis of big powder diffraction data

We present Parameter Quantification Network(PQ-Net),a regression deep convolutional neural network providing quantitative analysis of powder X-ray diffraction patterns from multi-phase systems.The network is tested against simulated and experimental datasets of increasing complexity with the last one being an X-ray diffraction computed tomography dataset of a multi-phase Ni-Pd/CeO_(2)-ZrO_(2)/Al_(2)O_(3) catalytic material system consisting of ca.20,000 diffraction patterns.It is shown that the network predicts accurate scale factor,lattice parameter and crystallite size maps for all phases,which are comparable to those obtained through full profile analysis using the Rietveld method,also providing a reliable uncertainty measure on the results.The main advantage of PQNet is its ability to yield these results orders of magnitude faster showing its potential as a tool for real-time diffraction data analysis during in situ/operando experiments.

反铁磁拓扑绝缘体MnBi_(2)Te_(4)/Bi_(2)Te_(3)超晶格具有不变近零能隙的表面态研究

磁性拓扑材料蕴含拓扑磁电效应等丰富拓扑物理现象,成为近年来拓扑量子材料研究热点.最近,在本征反铁磁拓扑绝缘体MnBi_(2)Te_(4)中发现了量子反常霍尔效应及轴子绝缘体态,使得此体系引发了广泛的关注.由MnBi_(2)Te_(4)及Bi_(2)Te_(3)插层得到的超晶格结构材料(MnBi_(2)Te_(4))m(Bi_(2)Te_(3))n,同样具有本征反磁序及非平庸拓扑相,为研究磁性与拓扑电子结构相互关系提供了重要的可调控材料平台.本文利用具有空间分辨能力的激光和同步辐射角分辨光电子能谱系统(ARPES),全面且系统地测量了此材料体系中Mn Bi4Te7的电子结构,发现在MnBi2Te4及Bi2Te3解理面均存在近零能隙的拓扑表面态;文章通过变温测量,发现其体态电子受到反铁磁序的强烈影响,但其拓扑表面态在反铁磁相变时保持近零能隙不变.这些结果印证了MnBi2Te4体系的不变近零能隙的普遍性,为理解中磁性与拓扑物态之间相互作用以及其调控提供了重要的谱学信息.

Molybdenum sputtering film characterization for high gradient accelerating structures

Technological advancements are strongly required to fulfill the demands of new accelerator devices with the highest accelerating gradients and operation reliability for the future colliders. To this purpose an extensive R^zD regarding molybdenum coatings on copper is in progress. In this contribution we describe chemical composition, deposition quality and resistivity properties of different molybdenum coatings obtained via sputtering. The deposited films are thick metallic disorder layers with different resistivity values above and below the molibdenum dioxide reference value. Chemical and electrical properties of these sputtered coatings have been characterized by Rutherford backscattering, XANES and photoemission spectroscopy. We will also consider multiple cells standing wave section coated by a molybdenum layer designed to improve the performance of X-Band accelerating systems.

Synchrotron Characterisation of Ultra-Fine Grain TiB_(2)/Al-Cu Composite Fabricated by Laser Powder Bed Fusion

Isotropy in microstructure and mechanical properties remains a challenge for laser powder bed fusion(LPBF)processed materials due to the epitaxial growth and rapid cooling in LPBF.In this study,a high-strength TiB_(2)/Al-Cu composite with random texture was successfully fabricated by laser powder bed fusion(LPBF)using pre-doped TiB_(2)/Al-Cu composite powder.A series of advanced characterisation techniques,including synchrotron X-ray tomography,correlative focussed ion beam-scanning electron microscopy(FIB-SEM),scanning transmission electron microscopy(STEM),and synchrotron in situ X-ray diffraction,were applied to investigate the defects and microstructure of the as-fabricated TiB_(2)/Al-Cu composite across multiple length scales.The study showed ultra-fine grains with an average grain size of about 0.86μm,and a random texture was formed in the as-fabricated condition due to rapid solidification and the TiB_(2)particles promoting heterogeneous nucleation.The yield strength and total elongation of the as-fabricated composite were 317 MPa and 10%,respectively.The contributions of fine grains,solid solutions,dislocations,particles,and Guinier-Preston(GP)zones were calculated.Failure was found to be initiated from the largest lack-of-fusion pore,as revealed by in situ synchrotron tomography during tensile loading.In situ synchrotron diffraction was used to characterise the lattice strain evolution during tensile loading,providing important data for the development of crystal-plasticity models.

Evaluating the morphology of the degradation layer of pure magnesium via 3D imaging at resolutions below 40 nm

Magnesium is attractive for the application as a temporary bone implant due to its inherent biodegradability,non-toxicity and suitable mechanical properties.The degradation process of magnesium in physiological environments is complex and is thought to be a diffusion-limited transport problem.We use a multi-scale imaging approach using micro computed tomography and transmission X-ray microscopy(TXM)at resolutions below 40 nm.Thus,we are able to evaluate the nanoporosity of the degradation layer and infer its impact on the degradation process of pure magnesium in two physiological solutions.Magnesium samples were degraded in simulated body fluid(SBF)or Dulbecco’s modified Eagle’s medium(DMEM)with 10%fetal bovine serum(FBS)for one to four weeks.TXM reveals the three-dimensional interconnected pore network within the degradation layer for both solutions.The pore network morphology and degradation layer composition are similar for all samples.By contrast,the degradation layer thickness in samples degraded in SBF was significantly higher and more inhomogeneous than in DMEM+10%FBS.Distinct features could be observed within the degradation layer of samples degraded in SBF,suggesting the formation of microgalvanic cells,which are not present in samples degraded in DMEM+10%FBS.The results suggest that the nanoporosity of the degradation layer and the resulting ion diffusion processes therein have a limited influence on the overall degradation process.This indicates that the influence of organic components on the dampening of the degradation rate by the suppression of microgalvanic degradation is much greater in the present study.