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Tower-Based Greenhouse Gas Measurement Network Design——The national institute of standards and technology North East Corridor Testbed

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Advances in Atmospheric Sciences 2017年第9期34卷 1095-1105页

作者： Israel LOPEZ-COTO Subhomoy GHOSH Kuldeep PRASAD James WHETSTONE national institute of standards and technology

The North-East Corridor （NEC） Testbed project is the 3rd of three NIST （national institute of standards and technology） greenhouse gas emissions testbeds designed to advance greenhouse gas measurements capabilities. A design approach for a dense observing network combined with atmospheric inversion methodologies is described. The Advanced Research Weather Research and Forecasting Model with the Stochastic Time-Inverted Lagrangian Transport model were used to derive the sensitivity of hypothetical observations to surface greenhouse gas emissions （footprints）. Unlike other network design algorithms, an iterative selection algorithm, based on a k-means clustering method, was applied to minimize the similarities between the temporal response of each site and maximize sensitivity to the urban emissions contribution. Once a network was selected, a synthetic inversion Bayesian Kalman filter was used to evaluate observing system performance. We present the performances of various measurement network configurations consisting of differing numbers of towers and tower locations. Results show that an overly spatially compact network has decreased spatial coverage, as the spatial information added per site is then suboptimal as to cover the largest possible area, whilst networks dispersed too broadly lose capabilities of constraining flux uncertainties. In addition, we explore the possibility of using a very high density network of lower cost and performance sensors characterized by larger uncertainties and temporal drift. Analysis convergence is faster with a large number of observing locations, reducing the response time of the filter. Larger uncertainties in the observations implies lower values of uncertainty reduction. On the other hand, the drift is a bias in nature, which is added to the observations and, therefore, biasing the retrieved fluxes.

关键词： greenhouse gases network design clustering analysis Kalman filter OSSE

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Effect of distribution shape on the melting transition, local ordering,and dynamics in a model size-polydisperse two-dimensional fluid

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Chinese Physics B 2024年第7期33卷 429-439页

作者： Jackson Pame Lenin S.Shagolsem Department of Physics National Institute of Technology Manipur

We study the effect of particle size polydispersity（δ） on the melting transition（T*）, local ordering, solid–liquid coexistence phase and dynamics of two-dimensional Lennard–Jones fluids up to moderate polydispersity by means of computer simulations. The particle sizes are drawn at random from the Gaussian（G） and uniform（U） distribution functions.For these systems, we further consider two different kinds of particles, viz., particles having the same mass irrespective of size, and in the other case the mass of the particle scales with its size. It is observed that with increasing polydispersity,the value of T*initially increases due to improved packing efficiency（φ） followed by a decrease and terminates at δ ≈8%（U-system） and 14%（G-system） with no significant difference for both mass types. The interesting observation is that the particular value at which φ drops suddenly coincides with the peak of the heat capacity（CP） curve, indicating a transition. The quantification of local particle ordering through the hexatic order parameter（Q6）, Voronoi construction and pair correlation function reveals that the ordering decreases with increasing δ and T. Furthermore, the solid–liquid coexistence region for the G-system is shown to be comparatively wider in the T –δ plane phase diagram than that for the U system. Finally, the study of dynamics reveals that polydisperse systems relax faster compared to monodisperse systems;however, no significant qualitative differences, depending on the distribution type and mass polydispersity, are observed.

关键词： dynamics ordering phase diagram polydispersity

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Evaluation of a hepatic biomarker of nutritional imbalance in juvenile red drum(Sciaenops ocellatus) fed 60% soybean meal-based diets using NMR-based metabolomics

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Animal Nutrition 2024年第1期16卷 45-61页

作者： Fabio Casu Aaron M.Watson Justin Yost T.Gibson Gaylord Daniel W.Bearden Michael R.Denson Marine Resources Research institute South Carolina Department of Natural Resources Bozeman Fish technology Center United States Fish and Wildlife Service Marine Biochemical Sciences Group Chemical Sciences Division National Institute of Standards and Technology Hollings Marine Laboratory

A 12-week feeding trial with juvenile red drum(Sciaenops ocellatus) fed high-soybean meal(SBM) diets was conducted to investigate a putative biomarker of nutritional imbalance, N-formimino-L-glutamate(FIGLU). Three fishmeal-free, 60% SBM pelleted diets(named B12, Fol, and Met, respectively) were tested to evaluate the effects on growth performance and tissue metabolite profiles of supplementation of vitamin B12(0.012 mg/kg), folate(10 mg/kg), methionine(1 g/kg) respectively, above basal supplementation levels. A fourth SBM-based diet(named B12/Fol/Met) was formulated with a combination of B12, folate, and methionine to attain the above-mentioned target concentrations. A fifth 60% SBM diet(named FWS) with methionine supplementation(1 g/kg above basal supplementation levels), enriched with taurine, lysine and threonine as well as minerals, was also tested. This diet contained formulation targets and additives which have allowed for replacing fishmeal with plant proteins in rainbow trout feeds. Control diets included a fishmeal-based diet(named FM), an unsupplemented basal 60% SBM diet(named SBM60), and a “natural” diet(named N) made up of equal parts of fish(cigar minnows), squid and shrimp as a positive reference for growth performance. Formulated feeds contained approximately 37% total crude protein, approximately 14% total crude lipid and were energetically balanced. Standard growth performance metrics were measured, and tissues(liver, muscle) were collected at week 12 to evaluate diet-induced metabolic changes using nuclear magnetic resonance(NMR)-based metabolomics.Our results show that the FWS diet outperformed all other SBM diets and the FM diet under all performance metrics(P<0.05). FIGLU was not detected in fish fed the N diet but was detected in those fed the SBM diets and the FM diet. Fish fed the FWS diet and the Met diet showed lower hepatic levels of FIGLU compared with the other SBM-based diets(P<0.05), suggesting that among the different supplementation regimes, methionine supplementation was associ

关键词： Aquaculture Metabolomics Nuclear magnetic resonance Red drum Soybean meal N-Formimino-L-glutamate

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Tantalum pentoxide:a new material platform for high-performance dielectric metasurface optics in the ultraviolet and visible region

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Light(Science & Applications) 2024年第1期13卷 142-152页

作者： Cheng Zhang Lu Chen Zhelin Lin Junyeob Song Danyan Wang Moxin Li Okan Koksal Zi Wang Grisha Spektor David Carlson Henri J.Lezec Wenqi Zhu Scott Papp Amit Agrawal School of Optical and Electronic Information&Wuhan national Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhanHubei 430074China national institute of standards and technology GaithersburgMD 20899USA University of Maryland College ParkMD 20742USA national institute of standards and technology BoulderCO 80305USA

Dielectric metasurfaces,composed of planar arrays of subwavelength dielectric structures that collectively mimic the operation of conventional bulk optical elements,have revolutionized the field of optics by their potential in constructing high-efficiency and multi-functional optoelectronic systems on chip.The performance of a dielectric metasurface is largely determined by its constituent material,which is highly desired to have a high refractive index,low optical loss and wide bandgap,and at the same time,be fabrication friendly.Here,we present a new material platform based on tantalum pentoxide(Ta2O5)for implementing high-performance dielectric metasurface optics over the ultraviolet and visible spectral region.This wide-bandgap dielectric,exhibiting a high refractive index exceeding 2.1 and negligible extinction coefficient across a broad spectrum,can be easily deposited over large areas with good quality using straightforward physical vapor deposition,and patterned into high-aspect-ratio subwavelength nanostructures through commonly-available fluorine-gas-based reactive ion etching.We implement a series of highefficiency ultraviolet and visible metasurfaces with representative light-field modulation functionalities including polarization-independent high-numerical-aperture lensing,spin-selective hologram projection,and vivid structural color generation,and the devices exhibit operational efficiencies up to 80%.Our work overcomes limitations faced by scalability of commonly-employed metasurface dielectrics and their operation into the visible and ultraviolet spectral range,and provides a novel route towards realization of high-performance,robust and foundry-manufacturable metasurface optics.

关键词： dielectric optics ultraviolet

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Dual-microcomb generation via a monochromatically pumped dual-mode microresonator

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Photonics Research 2024年第1期12卷 163-171页

作者： RUNLIN MIAO KE YIN CHAO ZHOU CHENXI ZHANG ZHUOPEI YU XIN ZHENG TIAN JIANG national Innovation institute of Defense technology Academy of Military Sciences PLA ChinaBeijing 100071China Beijing institute for Advanced Study National University of Defense TechnologyBeijing 100000China College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China College of Electronic Science and technology National University of Defense TechnologyChangsha 410073China institute for Quantum Science and technology College of ScienceNational University of Defense TechnologyChangsha 410073China

Microcombs have enabled a host of cutting-edge applications from metrology to communications that have garnered significant attention in the last decade.Nevertheless,due to the thermal instability of the microresonator,additional control devices like auxiliary lasers are indispensable for single-soliton generation in some scenarios.Specifically,the increased system complexity would be too overwhelming for dual-microcomb generation.Here,we put forward a novel approach to mitigate the thermal instability and generate the dual-microcomb using a compact system.This process is akin to mode-division multiplexing,as the dual-microcombs are generated by pumping the dual-mode of a single Si_(3)N_(4) microresonator with a continuous-wave laser.Both numerical simulations and experimental measurements indicate that this innovative technique could offer a straightforward way to enlarge the soliton existence range,allowing entry into the multistability regime and triggering another microcomb alongside the main soliton pulse.This outcome not only shines new light on the interaction mechanism of microresonator modes but also provides an avenue for the development of dual-microcomb-based ranging and low phase noise microwave generation.

关键词： resonator pumped pumping

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Bioinspired sensing-memory-computing integrated vision systems: biomimetic mechanisms, design principles, and applications

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Science China(Information Sciences) 2024年第5期67卷 5-27页

作者： Yujie HUANG Yinlong TAN Yan KANG Yabo CHEN Yuhua TANG Tian JIANG institute for Quantum Information and State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology College of Advanced Interdisciplinary Studies National University of Defense Technology institute for Quantum Science and technology College of ScienceNational University of Defense Technology

With the explosion of sensory data in the Internet of Things(Io T) era, conventional machine vision systems are becoming increasingly difficult to meet the requirements of high efficiency, low energy consumption, and low latency due to their inherent shortcomings of separate sensing, memory, and computing units. Inspired by the retina and neuromorphic computing, the sensing-memory-computing integrated vision system(SMCVS) that features low power consumption, low latency, and high parallelism has been considered a promising technology to surpass the von Neumann architecture and realize strong artificial intelligence.Meanwhile, novel materials like two-dimensional semiconductors and quantum dots with novel optoelectronic performance provide hardware carriers for implementing integrated sensing-memory-computing architectures,attracting considerable attention. This paper reviews the recent research progress in bioinspired vision systems in terms of biomimetic mechanisms, design principles, computational architectures, and applications.Firstly, the biomimetic mechanisms are illustrated to guide the design of high-performance artificial visual perception systems. Then the research progress of optoelectronic-synapse-based bioinspired vision systems in the device principles and applications including image filtering, color recognition, visual adaptation, and motion detection are summarized. Finally, the challenges and future developing directions of the SMCVS are provided regarding bionic application, architecture design, and device fabrication.

关键词： sensing-memory-computing architecture neuromorphic computing retinomorphic device image recognition visual system

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Influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 563-580页

作者： N.HUMNEKAR D.SRINIVASACHARYA Department of Mathematics National Institute of TechnologyWarangal 506004TelanganaIndia

The influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel is investigated.The DarcyBrinkman model is used to characterize the fluid flow dynamics in porous materials.The analytical solutions are obtained for the unidirectional and completely developed flow.Based on a normal mode analysis,the generalized eigenvalue problem under a perturbed state is solved.The eigenvalue problem is then solved by the spectral method.Finally,the critical Rayleigh number with the corresponding wavenumber is evaluated at the assigned values of the other flow-governing parameters.The results show that increasing the Darcy number,the Lewis number,the Dufour parameter,or the Soret parameter increases the stability of the system,whereas increasing the inclination angle of the channel destabilizes the flow.Besides,the flow is the most unstable when the channel is vertically oriented.

关键词： nanofluid inclined channel variable viscosity linear stability double dif-fusion porous medium

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A review of understanding electrocatalytic reactions in energy conversion and energy storage systems via scanning electrochemical microscopy

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Journal of Energy Chemistry 2024年第4期91卷 155-177页

作者： Jihye Park Jong Hwan Lim Jin-Hyuk Kang Jiheon Lim Ho Won Jang Hosun Shin Sun Hwa Park Interdisciplinary Materials Measurement institute Korea Research Institute of Standards and ScienceDaejeon 34113Republic of Korea Department of Material Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Department of Applied Measurement Science University of Science and TechnologyDaejeon 34113Republic of Korea

To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for energy.Achieving optimal energy efficiency and cost competitiveness in these systems requires the strategic design of electrocatalysts,coupled with a thorough comprehension of the underlying mechanisms and degradation behavior occurring during the electrocatalysis processes.Scanning electrochemical microscopy(SECM),an analytical technique for studying surface electrochemically,stands out as a powerful tool offering electrochemical insights.It possesses remarkable spatiotemporal resolution,enabling the visualization of the localized electrochemical activity and surface topography.This review compiles crucial research findings and recent breakthroughs in electrocatalytic processes utilizing the SECM methodology,specifically focusing on applications in electrolysis,fuel cells,and metal–oxygen batteries within the realm of energy conversion and storage systems.Commencing with an overview of each energy system,the review introduces the fundamental principles of SECM,and aiming to provide new perspectives and broadening the scope of applied research by describing the major research categories within SECM.

关键词： Scanning electrochemical microscopy Electrocatalyst Electrocatalysis Water splitting Fuel cell Metal-oxygen battery

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RSPO2 as Wnt signaling enabler: Important roles in cancer development and therapeutic opportunities

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Genes & Diseases 2024年第2期11卷 788-806页

作者： Ankit Srivastava Deeksha Rikhari Sameer Srivastava Department of Biotechnology Motilal Nehru National Institute of TechnologyAllahabadUttar Pradesh 211004India

R-spondins are secretory proteins localized in the endoplasmic reticulum and Golgi bodies and are processed through the secretory pathway.Among the R-spondin family,RSPO2 has emanated as a novel regulator of Wnt signaling,which has now been acknowledged in numerous in vitro and in vivo studies.Cancer is an abnormal growth of cells that proliferates and spreads uncontrollably due to the accumulation of genetic and epigenetic factors that constitutively activate Wnt signaling in various types of cancer.Colorectal cancer (CRC) begins when cells in the colon and rectum follow an indefinite pattern of division due to aberrant Wnt activation as one of the key hallmarks.Decades-long progress in research on R-spondins has demonstrated their oncogenic function in distinct cancer types,particularly CRC.As a critical regulator of the Wnt pathway,it modulates several phenotypes of cells,such as cell proliferation,invasion,migration,and cancer stem cell properties.Recently,RSPO mutations,gene rearrangements,fusions,copy number alterations,and altered gene expression have also been identified in a variety of cancers,including CRC.In this review,we addressed the recent updates regarding the recurrently altered R-spondins with special emphasis on the RSPO2 gene and its involvement in potentiating Wnt signaling in CRC.In addition to the compelling physiological and biological roles in cellular fate and regulation,we propose that RSPO2 would be valuable as a potential biomarker for prognostic,diagnostic,and therapeutic use in CRC.

关键词： CRC Gene fusion R-Spondins RSPO2 Therapeutics Wnt signaling

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Machine-learned wearable sensors for real-time hand-motion recognition: toward practical applications

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national Science Review 2024年第2期11卷 231-263页

作者： Kyung Rok Pyun Kangkyu Kwon Myung Jin Yoo Kyun Kyu Kim Dohyeon Gong Woon-Hong Yeo Seungyong Han Seung Hwan Ko Department of Mechanical Engineering Seoul National University IEN Center for Human-Centric Interfaces and Engineering Institute for Electronics and NanotechnologyGeorgia Institute of Technology School of Electrical and Computer Engineering Georgia Institute of Technology Department of Chemical Engineering Stanford University Department of Mechanical Engineering Ajou University George W.Woodruff School of Mechanical Engineering Georgia Institute of Technology institute of Advanced Machinery and Design(SNU-IAMD) Seoul National University

Soft electromechanical sensors have led to a new paradigm of electronic devices for novel motion-based wearable applications in our daily lives. However, the vast amount of random and unidentified signals generated by complex body motions has hindered the precise recognition and practical application of this technology. Recent advancements in artificial-intelligence technology have enabled significant strides in extracting features from massive and intricate data sets, thereby presenting a breakthrough in utilizing wearable sensors for practical applications. Beyond traditional machine-learning techniques for classifying simple gestures, advanced machine-learning algorithms have been developed to handle more complex and nuanced motion-based tasks with restricted training data sets. Machine-learning techniques have improved the ability to perceive, and thus machine-learned wearable soft sensors have enabled accurate and rapid human-gesture recognition, providing real-time feedback to users. This forms a crucial component of future wearable electronics, contributing to a robust human–machine interface. In this review, we provide a comprehensive summary covering materials, structures and machine-learning algorithms for hand-gesture recognition and possible practical applications through machine-learned wearable electromechanical sensors.

关键词： wearable sensor soft electronics artificial intelligence machine learning human–machine interfaces gesture recognition

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