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A detailed comparison of the composition of(RE)-Ba-cu-O-Ag bulk superconductors

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Superconductivity 2024年第1期9卷 87-94页

作者： J.V.J.congreve y.Shi A.R.dennis H.Druiff N.c.Tutt D.A.cardwell J.H.Durrell Department of Engineering University of CambridgeCambridgeUK

The homogeneity of the microstructure and composition are critical in determining the properties of rare earthbarium‐cuprate,single grain bulk superconductors[(RE)BcO].The magnitude of the trapped magnetic field achieveable in these technologically important materials,in particular,is influenced heavily by the size and distribution of(RE)_(2)BacuO_(x)(RE‐211)flux pinning inclusions in the bulk microstructure,whereas the size and distribution of silver agglomerates present within the bulk superconducting matrix correlate directly with improved mechanical *** careful engineering,these materials have significant potential for application in range of devices related to energy storage,medicine,electro‐magnetic machinery and microelectronic *** of(RE)BcO bulk superconductors typically involves heating a powder compact above its peritectic decomposition temperature followed by slow cooling to facilitate the growth of a single ***(RE)BcO composition has a different peritectic temperature and growth rate,which,therefore,necessitates different requirements in the heating *** fabrication temperature and growth rate,for example,may have an effect on the RE‐211 and silver distribution,which may,in turn,affect the superconducting properties of the resulting single *** this work we compare the distributions of silver and RE‐211 in the single grain microstructures of y.c.Ag,GdBcO‐Ag,EuBcO‐Ag and SmBcO‐Ag bulk superconductors using optical microscopy,scanning electron microscopy and energy dispersive X‐ray *** observe that the distributions are very similar along both the a/b‐axis and c‐axis of these *** suggests that factors other than the maximum temperature used to achieve peritectic decomposition and the rate of single grain growth are particularly influential in determining the properties of the as‐processed samples in the top seeded melt growth *** observation demonstrates there is freedom to us

关键词： y.c.‐Ag GdBcO‐Ag SmBcO‐Ag EuBcO‐Ag composition Bulk superconductor

The trxG protein ULT1 regulates Arabidopsis organ size by interacting with TcP14/15 to antagonize the LIM peptidase DA1 for H3K4me3 on target genes

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Plant communications 2024年第4期5卷 255-274页

作者： Fan Xu Huixue Dong Weijun Guo Liang le yexing Jing Jennifer c.Fletcher Jiaqiang Sun Li Pu Biotechnology Research Institute Chinese Academy of Agricultural SciencesBeijing 100081China State Key Laboratory of crop Gene Resources and Breeding Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijing 100081China Department of Plant and Microbial Biology University of CaliforniaBerkeleyBerkeleyCA 94720USA Plant Gene Expression center United States Department of Agriculture-Agricultural Research ServiceAlbanyCA 94710USA These authors contributed equally to this article

Plant organ size is an important agronomic trait that makes a significant contribution to plant *** its central importance,the genetic and molecular mechanisms underlying organ size control remain to be fully ***,we report that the trithorax group protein ULTRAPETALA1(ULT1)interacts with the TEOSINTE BRANcHED1/cycLOIDEA/PcF14/15(TcP14/15)transcription factors by antagonizing the LIN-11,ISL-1,and MEc-3(LIM)peptidase DA1,thereby regulating organ size in *** of ULT1 function significantly increases rosette leaf,petal,silique,and seed size,whereas overexpression of ULT1 results in reduced organ ***1 associates with TcP14 and TcP15 to co-regulate cell size by affecting cellular *** analysis revealed that ULT1 and TcP14/15 regulate common target genes involved in endoreduplication and leaf ***1 can be recruited by TcP14/15 to promote lysine 4 of histone H3 trimethylation at target genes,activating their expression to determinefinal cell ***,we found that ULT1 influences the interaction of DA1 and TcP14/15 and antagonizes the effect of DA1 on TcP14/15 ***,ourfindings reveal a novel epigenetic mechanism underlying the regulation of organ size in Arabidopsis.

关键词： ULT1 TcP DA1 organ size endoreduplication

Simulating gamma-ray production from cosmic rays interacting with the solar atmosphere in the presence of coronal magnetic fields

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chinese Physics c 2024年第4期48卷 159-173页

作者：李哲吳震宇陈松战南云程何会海 Institute of High Energy Physics Chinese Academy of ScienceBeijing 100049China Department of Physics The Chinese University of Hong KongShatinNew TerritoriesHong KongChina School of Physical Sciences University of Chinese Academy of ScienceBeijing 100049China

cosmic rays can interact with the solar atmosphere and produce a slew of secondary messengers,making the Sun a bright gamma-ray source in the *** observations with Fermi-LAT have shown that these interactions must be strongly affected by solar magnetic fields in order to produce a wide range of observational features,such as a high flux and hard ***,the detailed mechanisms behind these features are still a *** this study,we tackle this problem by performing particle-interaction simulations in the solar atmosphere in the presence of coronal magnetic fields using the potential field source surface(PFSS)*** find that low-energy(~GeV)gamma-ray production is significantly enhanced by the coronal magnetic fields,but the enhancement decreases rapidly with *** enhancement directly.c.rrelates with the production of gamma rays with large deviation angles relative to the input cosmic-ray *** conclude that coronal magnetic fields are essential for correctly modeling solar disk gamma rays below 10 GeV,but above that,the effect of coronal magnetic fields *** magnetic field structures are needed to explain the high-energy disk emission.

关键词： solar gamma-ray corona magnetic field Geant4 simulation hadronic interaction

Quantitative and qualitative subgenomic RNA profiles of SARS-coV-2 in respiratory samples: A comparison between Omicron BA.2 and non-VOc-D614G

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Virologica Sinica 2024年第2期39卷 218-227页

作者： Zigui chen Rita Way yin ng Grace Lui Lowell Ling Agnes S.y.le.ng chit chow Siaw Shi Boon Wendy.c.S.Ho Maggie Haitian Wang Renee Wan yi chan Albert Martin Li David Shu cheong Hui Paul Kay Sheung chan Department of Microbiology Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Medicine and Therapeutics Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Anaesthesia and Intensive care Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Paediatrics Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Anatomical and cellular Pathology Faculty of MedicineThe Chinese University of Hong KongHong KongChina Jockey.c.ub School of Public Health and Primary.c.re Faculty of MedicineThe Chinese University of Hong KongHong KongChina Stanley Ho centre for Emerging Infectious Diseases Faculty of MedicineThe Chinese University of Hong KongHong KongChina

The SARS-coV-2 Omicron variants are notorious for their transmissibility,but little is known about their subgenomic RNA(sgRNA)*** study applied RNA-seq to delineate the quantitative and qualitative profiles of canonical sgRNA of 118 respiratory samples collected from patients infected with Omicron BA.2 and compared with 338 patients infected with non-variant of concern(non-VOc)-D614G.A unique characteristic profile depicted by the relative abundance of 9 canonical sgRNAs was reproduced by both BA.2 and non-VOcD614G regardless of host gender,age and presence of ***,such profile was lost in samples with low viral load,suggesting a potential application of sgRNA pattern to indicate viral activity of individual patient at a specific time point.A characteristic qualitative profile of canonical sgRNAs was also reproduced by both BA.2 and *** presence of a full set of canonical sgRNAs carried a coherent correlation with crude viral load(AUc¼0.91,95%cI 0.88–0.94),and sgRNA ORF7b was identified to be the best surrogate marker allowing feasible routine application in characterizing the infection status of individual *** potentials in using sgRNA as a target for vaccine and antiviral development are worth pursuing.

关键词： coronavirus SARS-coV-2 Omicron BA.2 Non-VOc-D614G RNA-seq Subgenomic RNA(sgRNA)

A review on the generation, determination and mitigation of Urban Heat Island

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Journal of Environmental Sciences 2008年第1期20卷 120-128页

作者： RIZWAN Ahmed Memon dennis y.c. le.ng LIU chunho Department of Mechanical Engineering the University of Hong Kong Hong Kong China.

Urban Heat Island （UHI） is considered as one of the major problems in the 21st century posed to human beings as a result of urbanization and industrialization of human civilization. The large amount of heat generated from urban structures, as they.c.nsume and re-radiate solar radiations, and from the anthropogenic heat sources are the main causes of UHI. The two heat sources increase the temperatures of an urban area as compared to its surroundings, which is known as Urban Heat Island Intensity （UHII）. The problem is even worse in cities or metropolises with large population and extensive economic activities. The estimated three billion people living in the urban areas in the world are directly exposed to the problem, which will be increased significantly in the near future. Due to the severity of the problem, vast research effort has been dedicated and a wide range of literature is available for the subject. The literature available in this area includes the latest research approaches, concepts, methodologies, latest investigation tools and mitigation measures. This study was carded out to review and summarize this research area through an investigation of the most important feature of UHI. It was concluded that the heat re-radiated by the urban structures plays the most important role which should be investigated in details to study urban heating especially the UHI. It was also concluded that the future research should be focused on design and planning parameters for reducing the effects of urban heat island and ultimately living in a better environment.

关键词： urban heat island (UHI) urbanization temperature rise mitigation

lean methane combustion over zeolite-supported Pd catalysts:Structure-performance relationship and deactivation mechanism

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Journal of Environmental Sciences 2024年第11期145卷 128-138页

作者： Xingyu Liu Jingkun chen Bowen Han Renna Li le Shi Zhongbiao Wu Xiaole Weng Key Laboratory of Environment Remediation and Ecological Health Ministry of EducationCollege of Environmental and Resource SciencesZhejiang UniversityHangzhou 310058China ZJU-Hangzhou Global Scientific and Technological Innovation center Zhejiang UniversityHangzhou 311200China Zhejiang Provincial Engineering Research centre of Industrial Boiler&Furnace Flue Gas Pollution control Hangzhou 310058China

Zeolites are a promising support for Pd catalysts in leanmethane(cH_(4))***,three types of zeolites(H-MOR,H-ZSM-5 and H-y)were selected to estimate their structural effects and deactivation mechanisms in cH_(4)*** show that variations in zeolite structure and surface acidity led to distinct changes in Pd ***/H-MOR with external high-dispersing Pd nanoparticles exhibited the best apparent activity,with activation energy(Ea)at 73 kJ/mol,while Pd/H-ZSM-5 displayed the highest turnover frequency(TOF)at 19.6×10^(−3)sec^(−1),presumably owing to its large particles with more step sites providing active sites in one particle for cH_(4)***/H-y with dispersed PdO within pore channels and/or Pd2+ions on ion-exchange sites yielded the lowest apparent activity and ***,Pd/H-MOR and Pd/H-ZSM-5 were both stable under a dry.c.ndition,but introducing 3 vol.%H_(2)O caused the cH_(4)conversion rate on Pd/H-MOR drop from 100%to 63%and that on Pd/H-ZSM-5 decreased remarkably from 82%to 36%.The former was shown to originate fromzeolite structural dealumination,and the latter principally owed to Pd aggregation and the loss of active PdO.

关键词： Methane combustion Pd catalysts Zeolite Structure-performance relationship Deactivation mechanism

Provenance and tectonic setting of sandstones of the Lomas coloradas Formation, cabullona Group, Sonora, México: constraints on petrography and geochemistry

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Journal of Palaeogeography 2024年第4期13卷 839-861页

作者： J.Madhavaraju D.G.Noriega-Montoya E.Ramirez-Montoya c.M.Gonz alez-le on John S.Armstrong-Altrin Estaci on Regional del Noroeste Instituto de GeologíaUniversidad Nacional Aut onoma de Mexico Ingeniería en Geociencias Universidad Estatal de Sonora Posgrado en ciencias de la Tierra Estaci on Regional del NoroesteInstituto de GeologíaUniversidad Nacional Aut onoma de Mexico Universidad Nacional Aut onoma de Mexico Instituto de Ciencias del Mar y LimnologíaUnidad de Procesos Oce anicos y CosterosCiudad Universitaria

The sedimentary rocks of the cabullona Group are well exposed in the cabullona Basin of northeastern Sonora, Mexico, which represent syntectonic sedimentation associated with Laramide-style deformation during the campanian-early Maastrichtian. The sandstones of the Lomas coloradas Formation deposited at the upper part of the cabullona Group. Petrography and geochemical(major, trace, and rare earth elements) studies were carried out on the sandstones to interpret the palaeoweathering, provenance,and tectonic setting of the Lomas coloradas Formation sandstones. Most of the sandstone modal analysis data plotted in the QFL and Qm FLt ternary diagrams fall into the fields of dissected arcs and recycled orogens,respectively. Geochemically the sandstones are classified as litharenites while few samples plot into the arkosic field. The chondrite-normalized REE diagrams for sandstones have LREE-enriched, relatively flat HREE patterns with negative Eu anomalies. cIA values and the A-cN-K diagram indicate a low intensity of chemical weathering in the source area. The tectonic setting diagram suggests both arc and rift settings for the studied sandstones. The bivariate and ternary diagrams and elemental ratios suggest a felsic source for the Lomas coloradas Formation. The average REE patterns of the studied sandstones are comparable with REE patterns of the granite from the caborca block, the rhyolite and granite of the Tarahumara Formation, and the Mesozoic felsic volcanic rocks. The modeled mixture of 40% Proterozoic granite, 30% Triassic arc, 10% Jurassic arc, and 20% Laramide arc represents the probable source rocks for the Lomas coloradas Formation.

关键词： Provenance Petrography Geochemistry Lomas coloradas Formation cabullona Group Mexico

Design of a Novel Exoskeleton with Passive Magnetic Spring Self-locking and Spine Lateral Balancing

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Journal of Bionic Engineering 2024年第1期21卷 236-255页

作者： Jhon F.Rodríguez-león Betsy D.M.chaparro-Rico Daniele cafolla Francesco Lago Eduardo castillo-castañeda Giuseppe carbone centro de Investigacion en ciencia Aplicada y Tecnologia Avanzada Unidad Querétaro MecatronicaInstituto Politécnico NacionalCerro Blanco 14176090 Colinas del CimatarioQuerétaroMexico Department of Mechanical Energy and Management EngineeringUniversity of CalabriaVia P.Bucci Cubo 46 C87036 RendeItaly Faculty of Science and Engineering Department of Computer ScienceSwansea UniversitySwanseaUK cESTER University of Cluj-NapocaCluj-NapocaRomania

This paper proposes a new upper-limb exoskeleton to reduce worker physical *** proposed design is based on a novel PRRRP(P-Prismatic;R-Revolute)kinematic chain with 5 passive Degrees of Freedom(DoF).Utilizing a magnetic spring,the proposed mechanism includes a specially designed locking mechanism that maintains any desired task *** proposed exoskeleton incorporates a balancing mechanism to alleviate discomfort and spinal torsional effects also helping in limb weight *** paper reports specific models and simulations to demonstrate the feasibility and effectiveness of the proposed *** experimental characterization is performed to validate the performance of the mechanism in terms of forces and physical strain during a specific application consisting of ceiling-surface drilling *** obtained results preliminarily validate the engineering feasibility and effectiveness of the proposed exoskeleton in the intended operation task thereby requiring the user to exert significantly less force than when not wearing it.

关键词： Assistive mechanism Exoskeleton Locking mechanism Bionic robot

Effects of building aspect ratio,diurnal heating scenario,and wind speed on reactive pollutant dispersion in urban street canyons

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Journal of Environmental Sciences 2012年第12期24卷 2091-2103页

作者： Nelson y.O.Tong dennis y.c.le.ng Department of Mechanical Engineering The University of Hong Kong

A photochemistry.c.upled computational fluid dynamics （cFD） based numerical model has been developed to model the reactive pollutant dispersion within urban street canyons, particularly integrating the interrelationship among diurnal heating scenario （solar radiation affections in nighttime, daytime, and sun-rise/set）, wind speed, building aspect ratio （building-height-to-street-width）, and dispersion of reactive gases, specifically nitric oxide （NO）, nitrogen dioxide （NO2） and ozone （O3） such that a higher standard of air quality in metropolitan cities can be achieved. Validation has been done with both experimental and numerical results on flow and temperature fields in a street canyon with bottom heating, which justifies the accuracy of the current model. The model was applied to idealized street canyons of different aspect ratios from 0.5 to 8 with two different ambient wind speeds under different diurnal heating scenarios to estimate the influences of different aforementioned parameters on the chemical evolution of NO, NO2 and 03. Detailed analyses of vertical profiles of pollutant concentrations showed that different diurnal heating scenarios could substantially affect the reactive gases exchange between the street canyon and air aloft, followed by respective dispersion and reaction. Higher building aspect ratio and stronger ambient wind speed were revealed to be, in general, responsible for enhanced entrainment of 03 concentrations into the street canyons along windward walls under all diurnal heating scenarios. comparatively, particular attention can be paid on the windward wall heating and nighttime uniform surface heating scenarios.

关键词： photochemistry reactive pollutant dispersion building aspect ratio diurnal heating scenario wind speed urban streetcanyon