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Lattice distortion releasing local surface strain on high-entropy alloys

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Nano Research 2022年第6期15卷 4775-4779页

作者： christian M.Clausen Jack k.Pedersen Thomas A.A.Batchelor Jan Rossmeisl Department of Chemistry University of Copenhagen2100 KøbenhavnØDenmark

High-entropy alloys(HEAs)have the potential to be a paradigm-shift for rational catalyst discovery but this new type of alloy requires a completely new approach to predict the surface *** addition to the ligand effect perturbing the surface–adsorbate bond,the random configuration of elements in the surface will also induce local strain effects due to the varying radii of neighboring *** modelling of HEA surface reactivity requires an estimate of this effect:To what degree is the adsorption of intermediates on these lattice distorted atomic environments affected by local strain?In this study,more than 3,500 density functional theory(DFT)calculated adsorption energies of*OH and*O adsorbed on the HEAs IrPdPtRhRu and AgAuCuPdPt are statistically analyzed with respect to the lattice constants of the alloys and the surfaces of each individual binding *** is found that the inherent distortion of the lattice structure in HEAs releases the local strain effect on the adsorption energy as the atomic environment surrounding the binding atom(s)settles into a relaxed *** is even observed to be true for clusters of atoms of which the sizes deviate significantly from the atomic environment in which they are *** elucidates an important aspect of binding site interaction with the neighboring atoms and thus constitutes a step towards a more accurate theoretical model of estimating the reactivity of HEA surfaces.

关键词： high-entropy alloys surface reactivity strain effect surface strain electrocatalysis oxygen reduction reaction

MoSe_(2)/WS_(2) heterojunction photodiode integrated with a silicon nitride waveguide for near infrared light detection with high responsivity

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Light(Science & Applications) 2023年第3期12卷 456-464页

作者： Rivka Gherabli S.R.k.C.Indukuri Roy Zektzer christian Frydendahl Uriel Levy Department of Applied Physics The Faculty of ScienceThe Center for Nanoscience and NanotechnologyThe Hebrew University of JerusalemJerusalem91904Israel

We demonstrate experimentally the realization and the characterization of a chip-scale integrated photodetector for the near-infrared spectral regime based on the integration of a MoSe_(2)/WS_(2) heterojunction on top of a silicon nitride *** configuration achieves high responsivity of~1 A W−1 at the wavelength of 780 nm(indicating an internal gain mechanism)while suppressing the dark current to the level of~50 pA,much lower as compared to a reference sample of just MoSe_(2) without WS_(2).We have measured the power spectral density of the dark current to be as low as~1×10^(−12) A Hz−0.5,from which we extract the noise equivalent power(NEP)to be~1×10^(−12) W Hz^(−0.5).To demonstrate the usefulness of the device,we use it for the characterization of the transfer function of a microring resonator that is integrated on the same chip as the *** ability to integrate local photodetectors on a chip and to operate such devices with high performance at the near-infrared regime is expected to play a critical role in future integrated devices in the field of optical communications,quantum photonics,biochemical sensing,and more.

关键词： heterojunction waveguide resonator

Estimation of Throughfall Erosivity in a Highly Diverse Forest Ecosystem Using Sand-Filled Splash Cups

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Journal of Earth Science 2010年第6期21卷 897-900页

作者： christian Geiβler Peter kühn 史学正 Thomas Scholten Chair of Physical Geography and Soil Science Eberhard Karls University Tübingen Institute of Soil Science Chinese Academy of Sciences

Sand-fflled splash cups were used to study the erosive power of rainfall and throughfall in the humid subtropics of Southeast China. The splash cup measurements yielded precise and reproducible results under both open field conditions and forest vegetation. The splash cups were exposed to specific forest stands of different ages and to selected species （Schima superba, Castanopsis eyrei, Daphniphyllum oldhamii, Lithocarpus glaber） in the Gutianshan （古田山） National Nature Reserve （GNNR）. The results of the measurements under forest vegetation show that the erosive power of throughfall drops to be 2.59 times higher compared to the open field. This accentuates the importance of shrub, herb and litter layers in forest ecosystems to protect the soil against erosion. Coalescing drops from leaves and branches （drips） are responsible for this notable gain in erosive power. Moreover, differences in sandloss between the investigated tree species （deciduous, evergreen） revealed that the erosion potential and the spatial heterogeneity of throughfall are species-specific. This highlights the importance of selecting specific species for afforestation projects considering the prevention of soil erosion.

关键词： Biodiversity and Ecosystem Functioning (BEF)-China biodiversity soil erosion soil erosion experiment splash cup throughfall erosivity.

Insensitive high explosives:Ⅳ. Nitroguanidine-Initiation & detonation

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Defence Technology（防务技术） 2019年第4期15卷 467-487页

作者： Ernst-christian koch Lutradyn-Energetic Materials

This paper reviews the detonative properties of low bulk density(LBD),high bulk density(HBD)Nitroguanidine(NGu)(1),CAS-No:[556-88-7]and 82 explosive formulations based on NGu reported in the public *** rank the performance of those formulations they are compared with 15 reference compositions containing both standard high explosives such as octogen(HMX)(2),hexogen(RDX)(3),pentaerythritol tetranitrate(PETN)(4),2,4,6-trinitrotoluene(TNT)(5)as well as insensitive high explosives such as 3-nitro-1,2,4-triazolone(NTO)(6),1,3,5-triamino-2,4,6-trinitrobenzene(TATB)(7),1,1-diamino-2,2-dinitroethylene(FOX-7)(8)and N-Guanylurea dinitramide(FOX 12)(9).NGu based formulations are superior to those based on FOX-12 or TATB and are a close match with FOX-7 based explosives,the latter just having higher Gurney Energies(-10%)and slightly higher detonation pressure(+2%).NGu based explosives even reach up to 78% of the detonation pressure,82% Gurney energy and up to 95% of detonation velocity of ***-NGu dissolves in many melt cast eutectics forming dense charges thereby eliminating the need for costly High Bulk Density *** based formulations are at the rock bottom of sensitiveness among all the above-mentioned explosives which contributes to the safety of these *** review gives 132 references to the public *** a review on the synthesis spectroscopy and sensitiveness of Nitroguanidine see Ref.[1].

关键词： Cook-off Detonation Insensitive munitions Nitroguanidine Shock sensitvity

Special materials in pyrotechnics Ⅶ: Pyrotechnics used in thermal batteries

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Defence Technology（防务技术） 2019年第3期15卷 254-263页

作者： Ernst-christian koch Lutradyn Energetic Materials Science & Technology

Thermal batteries are unique direct current(DC) electrical power sources with long shelf live, high reliability and higher power density than classical alkaline batteries. This paper gives a brief overview into the working principle of thermal batteries and reviews the properties of zirconium/barium chromate(Zr/BaCrO4) pyrolant previously used as first fire and iron/potassium perchlorate(Fe/kClO4) pyrolant(Heat), commonly applied as heating pellet in thermal batteries and its hazard properties. The review gives 64 references to the public domain. CAS-Nos. Zr: [7440-67-7], BaCrO4: [10294-40-3], Fe: [7439-89-6], kClO4: [7778-74-7], Viton: [9011-17-0].CAS-Nos. Zr: [7440-67-7], BaCrO4: [10294-40-3], Fe: [7439-89-6], kClO4: [7778-74-7], Viton: [9011-17-0].

关键词： Barium chromate Heat-powder Iron Lithium Molten salt Potassium perchlorate Pyrotechnics Thermal battery Zirconium

Numerical Study on Rising Dynamics and Coalescence of Bubbles

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Numerical Study on Rising Dynamics and Coalescence of Bubble...

作者： christian k Y Mulbah 江苏大学

学位级别：硕士

气泡在黏性液体中上升时中表现出的动力学特征是多个工程领域关注的热点问题。本文借助计算流体动力学(CFD)方法和流体体积(VOF)多相流模型,对单气泡和多气泡上升过程进行了二维和三维数值模拟,对数值模型进行了有效性验证。在第一项研... 详细信息

气泡在黏性液体中上升时中表现出的动力学特征是多个工程领域关注的热点问题。本文借助计算流体动力学(CFD)方法和流体体积(VOF)多相流模型,对单气泡和多气泡上升过程进行了二维和三维数值模拟,对数值模型进行了有效性验证。在第一项研究工作中,对在去离子水中上升中的甲烷(CH)气泡进行了研究,将去离子水的压强和温度分别设为13 MPa和5℃,选择CH气泡的直径范围为3.0 mm–6.0 mm。数值模拟结果表明:在高压和低温条件下,气泡轨迹、瞬时液体速度分布和气泡的尾流结构表现出独特的特征,气泡尾流中出现了复杂的旋涡结构。相对于常温常压环境,在高压和低温去离子水中的气泡速度较低。对气泡行为进行了无量纲分析,结果表明气泡直径显著影响其阻力系数。将去离子水和海水中的气泡行为进行了系统的对比分析,发现在13 MPa和5℃的去离子水中,气泡的上升特性更为复杂,直径为4.5 mm和6.0 mm的气泡附近出现明显的旋涡。在第二项研究工作中,采用三维非定常多相流动数值模拟研究了多气泡的上升过程。考虑了气泡尺寸对气泡上升行为和相互作用的影响,气泡尺寸范围为4.0 mm–10.0 mm。研究了同轴双气泡和三角形初始气泡排列方式。借助实验结果对数值模拟方案的有效性进行了验证。通过数值模拟获得了气泡几何形状随时间的变化、气泡速度和气泡附近的流动结构。结果表明,流动结构与气泡形状和上升相匹配;相对于同轴排列方式,侧向气泡的参与导致气泡间的聚并延迟。对于小尺寸气泡,第一次聚并发生在位于下方的两个气泡之间;随着气泡尺寸的增加,第一次聚并出现在上气泡和左下气泡之间;新形成的气泡的上升速度迅速下降,并且其形状在很大程度上与聚并前的单气泡有关。

关键词：甲烷气泡气泡轨迹气泡尺寸横向力气泡尾流 VOF模型

Plastid Signals and the Bundle Sheath： Mesophyll Development in Reticulate Mutants

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Molecular Plant 2014年第1期7卷 14-29页

作者： Peter k. Lundquist christian Rosar Andrea Brautigam Andreas P.M. Weber Institute for Plant Biochemistry and Cluster of Excellence on Plant Sciences (CEPLAS) Heinrich-Neine-Universitat Universitatsstrasse 1 40225 Dusseldorf Germany Alte StraBe 2 34225 Baunatal Germany

The development of a plant leaf is a meticulously orchestrated sequence of events producing a complex organ comprising diverse cell types. The reticulate class of leaf variegation mutants displays contrasting pigmentation between veins and interveinal regions due to specific aberrations in the development of mesophyll cells. Thus, the reticulate mutants offer a potent tool to investigate cell-type-specific developmental processes. The discovery that most mutants are affected in plastid-localized, metabolic pathways that are strongly expressed in vasculature-associated tis- sues implicates a crucial role for the bundle sheath and their chloroplasts in proper development of the mesophyll cells. Here, we review the reticulate mutants and their phenotypic characteristics, with a focus on those in Arabidopsis thali- ana. Two alternative models have been put forward to explain the relationship between plastid metabolism and meso- phyll cell development, which we call here the supply and the signaling hypotheses. We critically assess these proposed models and discuss their implications for leaf development and bundle sheath function in C3 species. The characteriza- tion of the reticulate mutants supports the significance of plastid retrograde signaling in cell development and highlights the significance of the bundle sheath in C3 photosynthesis.

关键词： reticulate mesophyll bundle sheath development intercellular signaling leaf variegation plastid.

Deep learning for geometric and semantic tasks in photogrammetry and remote sensing

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Geo-Spatial Information Science 2020年第1期23卷 10-19页

作者： christian Heipke Franz Rottensteiner Institute of Photogrammetry and GeoInformation(PI) Leibniz University HannoverHannoverGermany

During the last few years,artificial intelligence based on deep learning,and particularly based on convolutional neural networks,has acted as a game changer in just about all tasks related to photogrammetry and remote *** have shown partly significant improvements in many projects all across the photogrammetric processing chain from image orientation to surface reconstruction,scene classification as well as change detection,object extraction and object tracking and recognition in image *** paper summarizes the foundations of deep learning for photogrammetry and remote sensing before illustrating,by way of example,different projects being carried out at the Institute of Photogrammetry and GeoInformation,Leibniz University Hannover,in this exciting and fast moving field of research and development.

关键词： Deep learning machine learning convolutional neural networks(CNN) example project from IPI

Intranasal neprilysin rapidly eliminates amyloid-beta plaques, but causes plaque compensations: the explanation why the amyloid-beta cascade may fail?

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Neural Regeneration Research 2022年第9期17卷 1881-1884页

作者： christian Humpel Laboratory of Psychiatry and Experimental Alzheimer’s Research Medical University of InnsbruckInnsbruckAustria

Neurodegenerative brain disorders are a major burden in our society,such as Alzheimer´s *** order to repair or prevent such diseases,drugs are designed which enter the brain,but the blood-brain barrier limits their entry and the search for alternative pathways is ***,we reported that intranasal delivery of the amyloid-beta degrading enzyme neprilysin eliminated amyloid-beta plaques in transgenic Alzheimer´s disease *** review describes the anatomical structure of the intranasal pathway,explains the intranasal delivery of pure neprilysin,cell-loaded neprilysin(platelets)and collagen-embedded neprilysin to destruct amyloid-beta plaques in Alzheimer´s disease in transgenic APP_SweDI mice and hypothesizes why this may cause compensation and why the amyloid-beta cascade hypothesis may fail.

关键词： amyloid-beta amyloid-beta degrading enzyme clear plaque collagen biomaterial intranasal neprilysin nose-to-brain