The Decarbonization of Construction—How Can Alkali-Activated Materials Contribute?

1.Introduction and context Enormous emphasis is currently being paid to the decarbonization of the global built environment as a leading priority for the engineering community and related industrial sectors[1].One of the main contributors to the overall emissions footprint of the built environment-and thus a cornerstone of efforts to achieve decarbonization-is the emissions profile of construction materials during their production and utilization.The cement and concrete sector is the largest-volume contributor to the emissions incurred in meeting the world’s construction material needs and is therefore targeted in the discussion of the deep,rapid decarbonization that must be achieved in order to minimize irreversible damage to the Earth and its ecosystems.

Carrier-Density-Determined Magnetoresistance in Semimetal SrIrO_(3)

SrIrO_(3),a Dirac material with a strong spin-orbit coupling(SOC),is a platform for studying topological properties in strongly correlated systems,where its band structure can be modulated by multiple factors,such as crystal symmetry,elements doping,oxygen vacancies,magnetic field,and temperature.Here,we find that the engineered carrier density plays a critical role on the magnetoelectric transport properties of the topological semimetal SrIrO_(3).The decrease of carrier density subdues the weak localization and the associated negative magnetoresistance,while enhancing the SOC-induced weak anti-localization.Notably,the sample with the lowest carrier density exhibits high-field positive magnetoresistance,suggesting the presence of a Dirac cone.In addition,the anisotropic magnetoresistance indicates the anisotropy of the electronic structure near the Fermi level.The engineering of carrier density provides a general strategy to control the Fermi surface and electronic structure in topological materials.

基于中子成像的水泥基材料毛细吸水动力学研究

总结了国内外有关水泥基材料毛细吸水的动力学机理及其现有模型,应用中子成像技术对其毛细吸水过程进行了可视化再现,对水分侵入的空间分布规律进行了定量分析。结果表明,在毛细孔吸附力作用下,水分前锋不断向水泥基材料内部推进,在吸水初期速度较快,后趋于平缓直至稳定;水分侵入曲线在深度和含量上同时增长,可以由线性+反S形模型来描述其空间分布特点,并与实测结果吻合良好;现有的"时间开方"及其修正模型对毛细吸水的后期预测不太合理,本文提出的渗透系数双曲线衰减模型更符合真实结果。

中子照相技术及其在混凝土材料研究中的应用

介绍了中子照相技术的原理和基本装置,并将其应用于混凝土材料的检测和研究中。结果表明:中子照相能够直观地检测钢筋混凝土内部的裂缝发展情况,并能实现对混凝土中水分侵入过程的可视化研究。在成像数据的基础上,对传统的水分侵入模型进行了修正,认为在水分侵入的初始阶段,水渗透系数为常数;吸水超过4h后,渗透系数则按指数函数衰减。

Hot deformation of Mg-Y-Zn alloy with a low content of the LPSO phase studied by in-situ synchrotron radiation diffraction

The compressive deformation behavior of the extruded WZ42(Mg98.5Y1Zn0.5 in at.%)magnesium alloy containing a low amount of long-period stacking ordered(LPSO)phase was studied by in-situ synchrotron radiation diffraction technique.Tests were conducted at temperatures between room temperature and 350℃.Detailed microstructure investigation was provided by scanning electron microscopy,particularly the backscattered electron imaging and electron backscatter diffraction technique.The results show that twinning lost its dominance and kinking of the LPSO phase became more pronounced with increasing deformation temperature.No cracks of the LPSO phase and no debonding r at the interface between the LPSO phase and the Mg matrix were observed at temperatures above 200℃.At 350℃,the LPSO phase lost its strengthening effect and the deformation of the alloy was mainly realized by the dynamic recrystallization of the Mg matrix.

Novel Synthesis Method of Nonst0ichiometric Na2-xlrO3 Crystal Structure, Transport and Magnetic Properties

Transition metal oxides with 4d or 5d metals are of great interest due to the competing interactions, of the Coulomb repulsion and the itineracy of the d-electrons, opening a possibility of building new quantum ground states. Particularly the 5d metal oxides containing Iridium have received significant attention within the last years, due to their unexpected physical properties, caused by a strong spin orbit coupling observed in It（IV）. A prominent example is the Mott-insulator Sr2IrO4. Another member of this family, the honeycomb lattice compound Na2IrO3, also being a Mott-insulator having, most probably, a Kitaev spin liquid ground state. By deintercalating sodium from Na2IrO3, the authors were able to synthesize a new honeycomb lattice compound with more than 50% reduced sodium content. The reduction of the sodium content in this layered compound leads to a change of the oxidation state of iridium from ＋ IV to ＋ V/＋ VI and a symmetry change from C2/c to P-3. This goes along with significant changes of the physical properties. Besides the vanishing magnetic ordering at 15 K, also the transport properties changes and instead insulating semiconducting properties are observed.

3-26 Research Progress in Group of Energy Materials in 2015

The fracture behavior is a very important aspect of the mechanical properties of structure materials. For highenergy ions, their range in steels can be significantly larger than the average size of grains of steels, thus their irradiation can change the bulk properties of steels. It is therefore possible to study the fracture behavior of steel specimens irradiated with high-energy ions.

3-23 Research Progress in Group of Energy Materials in 2014

The progress of research going on in Group of Energy Materials (GEM), Material Research Center, in 2014 isin the following three aspects.1. Facility developmentIn order to push forward our study on fusion reactor materials, we upgraded the irradiation terminal (128#)of the sector focused cyclotron (SFC) at HIRFL, by developing a new specimen stage specific for irradiation withlow-fluence scattered ions. So far the terminal is capable of irradiation to both very low fluences (106 ions/cm2) andvery high fluences (typically 1016 ions/cm2) for various materials. Specimen temperature can be readily controlledusing the L-N2 cooling stage or the the high-T stage (up to 600 oC). Our recent investigation with transmissionelectron microscopy (TEM) of the defects produced by high-energy Ne ions in steel specimens provides a clearevidence that defects were produced uniformly along the depth in the specimen, indicating that the energy degraderof the terminal works effectively to disperse the ion energy in a wide range. A photo of the terminal together witha SRIM estimate of depth profiles of damage in an 8% Cr reduced activation ferritic/martensitic steel (RAFMS) isshown in Fig. 1.

Spin order and dynamics in the topological rare-earth germanide semimetals

The REAl(Si,Ge)(RE=rare earth)family,known to break both the inversion-and time-reversal symmetries,represents one of the most suitable platforms for investigating the interplay between correlated-electron phenomena and topologically nontrivial bands.Here,we report on systematic magnetic,transport,and muon-spin rotation and relaxation(μSR)measurements on(Nd,Sm)AlGe single crystals,which exhibit antiferromagnetic(AFM)transitions at T_(N)=6.1 and 5.9 K,respectively.In addition,NdAlGe undergoes also an incommensurate-to-commensurate ferrimagnetic transition at 4.5 K.Weak transverse-fieldμSR measurements confirm the AFM transitions,featuring a~90%magnetic volume fraction.Zero-field(ZF)μSR measurements reveal a more disordered internal field distribution in NdAlGe than in SmAlGe,reflected in a larger transverse muon-spin relaxation rateλTat T<<T_(N).This may be due to the complex magnetic structure of NdAlGe,which undergoes a series of metamagnetic transitions in an external magnetic field,while SmAlGe shows only a robust AFM order.In NdAlGe,the topological Hall effect(THE)appears between the first and the second metamagnetic transitions for H‖c,while it is absent in SmAlGe.Such THE in NdAlGe is most likely attributed to the field-induced topological spin textures.The longitudinal muon-spin relaxation rateλL,diverges near the AFM order,followed by a clear drop at T<T_N.In the magnetically ordered state,spin fluctuations are significantly stronger in NdAlGe than in SmAlGe.In general,our longitudinal-fieldμSR data indicate vigorous spin fluctuations in NdAlGe,thus providing valuable insights into the origin of THE and of the possible topological spin textures in REAl(Si,Ge)Weyl semimetals.

Generation of millijoule-level sub-5 fs violet laser pulses

We demonstrate the generation,spectral broadening and post-compression of second harmonic pulses using a thin beta barium borate(BBO)crystal on a fused-silica substrate as the nonlinear interaction medium.By combining second harmonic generation in the BBO crystal with self-phase modulation in the fused-silica substrate,we efficiently generate millijoule-level broadband violet pulses from a single optical component.The second harmonic spectrum covers a range from long wave ultraviolet(down to 310 nm)to visible(up to 550 nm)with a bandwidth of 65 nm.Subsequently,we compress the second harmonic beam to a duration of 4.8 fs with a pulse energy of 0.64 mJ(5 fs with a pulse energy of 1.05 mJ)using chirped mirrors.The all-solid free-space apparatus is compact,robust and pulse energy scalable,making it highly advantageous for generating intense second harmonic pulses from near-infrared femtosecond lasers in the sub-5 fs regime.

Hyper spectral resolution stimulated Raman spectroscopy with amplified fs pulse bursts

We present a novel approach for Stimulated Raman Scattering(SRS)spectroscopy in which a hyper spectral resolution and high-speed spectral acquisition are achieved by employing amplified offset-phase controlled fs-pulse bursts.We investigate the method by solving the coupled non-linear Schrödinger equations and validate it by numerically characterizing SRS in molecular nitrogen as a model compound.The spectral resolution of the method is found to be determined by the inverse product of the number of pulses in the burst and the intraburst pulse separation.The SRS spectrum is obtained through a motion-free scanning of the offset phase that results in a sweep of the Raman-shift frequency.Due to high spectral resolution and fast motion-free scanning the technique is beneficial for a number SRS-based applications such as gas sensing and chemical analysis.

Advancing oxygen separation:insights from experimental and computational analysis of La_(0.7)Ca_(0.3)Co_(0.3)Fe_(0.6)M_(0.1)O_(3-δ)(M=Cu,Zn)oxygen transport membranes

In this study,perovskite-type La_(0.7)Ca_(0.3)Co_(0.3)Fe_(0.6)M_(0.1)O_(3-δ)(M=Cu,Zn)powders were synthesized using a scalable reverse co-precipitation method,presenting them as novel materials for oxygen transport membranes.The comprehensive study covered various aspects including oxygen permeability,crystal structure,conductivity,morphology,CO_(2) tolerance,and long-term regenerative durability with a focus on phase structure and composition.The membrane La_(0.7)Ca_(0.3)Co_(0.3)Fe_(0.6)M_(0.1)O_(3-δ)exhibited high oxygen permeation fluxes,reaching up to 0.88 and 0.64 mL·min^(−1)·cm^(−2) under air/He and air/CO_(2) gradients at 1173 K,respectively.After 1600 h of CO_(2) exposure,the perovskite structure remained intact,showcasing superior CO_(2) resistance.A combination of first principles simulations and experimental measurements was employed to deepen the understanding of Cu/Zn substitution effects on the structure,oxygen vacancy formation,and transport behavior of the membranes.These findings underscore the potential of this highly CO_(2)-tolerant membrane for applications in high-temperature oxygen separation.The enhanced insights into the oxygen transport mechanism contribute to the advancement of next-generation membrane materials.

青藏高原冰芯记录揭示早-中全新世发生多次融水事件

Understanding the impact of meltwater discharge during the final stage of the Laurentide Ice Sheet(LIS)has important implications for predicting sea level rise and climate change.Here we present a highresolution ice-core isotopic record from the central Tibetan Plateau(TP),where the climate is sensitive to the meltwater forcing,and explore possible signals of the climate response to potential LIS meltwater discharges in the early to mid-Holocene.The record shows four abrupt large fluctuations during the 7–9 ka BP(kiloannum before present),reflecting large shifts of the mid-latitude westerlies and the Indian summer monsoon(ISM)over this period,and they corresponded to possible LIS freshwater events documented in other paleoclimate records.Our study suggests that multiple rapid meltwater discharge events might have occurred during the final stage of LIS.The finding implies the possibility of rapid sea level rise and unstable climate in the transition zone between the mid-latitude westerlies and the ISM due to fast polar ice retreat under the anthropogenic global warming.

高能重离子辐照的ODS铁素体钢脆化效应研究

与传统的铁素体钢相比,氧化物弥散强化(ODS)的铁素体钢具有更优的耐高温和抗辐照性能,近年来成为先进核能装置重要的候选结构材料。在HIRFL的扇聚焦型回旋加速器(SFC)材料辐照终端,对一种氧化物弥散强化(ODS)铁素体钢MA956进行了高能Ne离子辐照实验,旨在研究级联碰撞损伤和惰性气体原子注入条件下该材料力学性能的变化。利用辐照终端的能量衰减装置将SFC出口123.4 Me V的离子能量分解为介于38.5～121.0 Me V之间的30个入射能量值,并通过双面辐照在厚度60μm的样品中均匀产生了损伤。辐照剂量为9×1016ions/cm2,在样品中的平均位移损伤为0.7 dpa,注入的Ne原子浓度为350 appm。辐照期间样品温度保持在440℃附近。对辐照前后的样品分别在室温和500℃下进行了小冲杆试验(Small-punch Test),获得了辐照前后样品的加载位移曲线,由此得到该辐照条件下样品的延性损失为18%～26%。通过扫描电子显微镜观察了断口形貌和厚度变化,估算了样品的等效断裂应变和断裂韧性。结果表明,MA956钢经过高能Ne离子辐照后等延伸率减小,断裂韧性降低,样品发生了一定的脆化。透射电镜结果说明氧化物弥散相界面处微空洞的形成可能是导致脆化的原因。

Topological surface states and flat bands in the kagome superconductor CsV_(3)Sb_(5)

Exotic quantum phenomena may appear in material systems with multiple orders or phases,where the mutual interactions can give rise to new physics beyond that of each component.Here,we report spectroscopic evidence for a unique combination of topology and correlation effects in the kagome superconductor CsV_(3)Sb_(5).Topologically nontrivial surface states are observed near the Fermi energy(E_(F)),indicating that the topological physics may be active upon entering the superconducting state.Flat bands are observed,suggesting that electron correlation effects are also at play in this system.Our results reveal the peculiar electronic structure of CsV_(3)Sb_(5),which holds the potential for realizing Majorana zero modes and anomalous superconducting states in kagome lattices.They also establish CsV_(3)Sb_(5)as a unique platform for exploring the interactions between the charge order,topology,correlation effects and superconductivity.

Revealing Liquid Metal Target Malfunctions by Means of Vibrations and Sound Pressure Monitoring

In the following paper an experiment dedicated to the accident protection system of a Liquid Metal Target is presented.The test was carried out at the liquid metal test stand(LIMETS)at PSI in which the malfunctioning of a target during operation was simulated.It could be demonstrated that measurements and the proper(on-line)analysis of target vibrations and surrounding sound pressure fields allow the detection of a malfunctions like deformation or detaching of structural elements immeresed in the flow.Amplitudes of acceleration sensors and microphones signals as well as frequencies of the disturbances' signals are prospective parameters to be used in an automated accident protection system as indicators for a target malfunction.

Simulation of 3D Porous Media Flows with Application to Polymer Electrolyte Fuel Cells

A 3D lattice Boltzmann(LB)model with twenty-seven discrete velocities is presented and used for the simulation of three-dimensional porous media flows.Its accuracy in combination with the half-way bounce back boundary condition is assessed.Characteristic properties of the gas diffusion layers that are used in polymer electrolyte fuel cells can be determined with this model.Simulation in samples that have been obtained via X-ray tomographic microscopy,allows to estimate the values of permeability and relative effective diffusivity.Furthermore,the computational LB results are compared with the results of other numerical tools,as well as with experimental values.

Whitlockite has a characteristic distribution in mammary microcalcifications and it is not associated with breast cancer

Dear Editor,Microcalcifications(MCs)are common findings in mammography and can be indicative of different degrees of malignancy,thus requiring multiple stereotaxis vacuumassisted biopsies under mammography to identify and characterize breast cancer[1,2].In many cases,however,the presence of MCs is not associated with the presence of a tumor.Therefore,a better understanding of the physical-chemical properties of MCs is needed to assess the relationship between their presence and breast cancer.

X-ray microscopic investigation of molecular orientation in a hole carrier thin film for organic solar cells

As dipyranylidenes are excellent hole carriers, applications in organic solar cells or organic light emitting diode are envisaged. In the present study, we investigate the morphology of 2,2＇,6,6＇-tetraphenyl-4,4＇-dipyranylidene （DIPO-Ph4） deposited under vacuum on a silicon nitride （Si3N4） substrate, a paradigmatic system for the study of molecular crystal/inorganic substrate interfaces. Samples with various coating ratios and different thermal treatments were prepared. The films were characterized by atomic force microscopy and scanning transmission X-ray microscopy to gain insight into material growth. The results show a change in orientation at a molecular level depending upon the evaporation conditions. We are now able to tailor an organic layer with a specific molecular orientation and a specific electronic behavior.