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Early stages of non-classic crystal growth

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Science China Chemistry 2011年第12期54卷 1867-1876页

作者： GREER heather f. EaStChem School of ChemistryUniversity of St Andrews

Investigation of early stages of crystal growth revealed that crystal growth in some systems may not follow the classic *** the early stages of inorganic crystal growth,precursor molecules and/or nanocrystallites may aggregate into large and disordered particles with the assistance of some polymers or *** crystallization of these aggregates would then take place to form shells with high crystallinity and density,followed by an extension of the crystallization from surface to *** so-called reversed crystal growth mechanism has been found in crystallization of several inorganic compounds including zeolites,perovskites,metals and metal oxides,and will be identified in more material *** establishment of this new crystal growth route gave us more freedom to control the morphology of crystals and to understand the formation mechanism of many natural *** article gives a brief review of the recent research in this field by featuring some typical examples of the reversed crystal growth.

关键词： reversed crystal growth hollow crystals core-shell particles electron microscopy

Exploration of petrographic,elemental,and material properties of dynamic failure-prone coals

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International Journal of Mining Science and Technology 2020年第1期30卷 69-75页

作者： heather Lawson Spokane Mining Research Division National Institute for Occupational Safety and HealthSpokaneWA 99207USA

The purpose of this study is to explore how the geochemical and petrographic components of coal may impact its physical properties and how these correlate with a history of reportable dynamic failure in coal *** failure events,also termed bumps,bounces,or bursts,are the explosive failures of rock in a mining *** events occur suddenly and often with no warning,resulting in worker injury up to and including fatality in greater than 60%of reportable cases through the Mine Safety and Health Administration(MSHA).A database of variables was compiled using publicly available datasets,which includes compositional geographic,strength,and Hardgrove grindability index(HGI)*** indicated that bumping coals were less mature,lower in carbon,higher in oxygen,softer,and less well cleated than coals that did not *** liptinite content was found to correlate with higher average uniaxial compressive strength(UCS)***,no clear and direct correlation between UCS and dynamic failure status was *** findings of this study established that differences existed between coals that had versus had not experienced reportable dynamic failure *** differences were inherent to the coal itself and were independent of mining-induced risk *** further illuminated how compositional attribute of coal influenced physical properties and began to clarify potential links between geochemistry and dynamic failure *** through the better understanding of risk can more effective mitigating strategies be enacted.

关键词： Dynamic failure Coal Bump Bounce Burst

Analysis of gateroad stability at two longwall mines based on field monitoring results and numerical model analysis

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International Journal of Mining Science and Technology 2019年第1期29卷 35-43页

作者： Gabriel S.Esterhuizen David f.Gearhart Ted Klemetti heather Dougherty Mark van Dyke National Institute for Occupational Safety and Health

Coal mine longwall gateroads are subject to changing loading conditions induced by the advancing longwall face. The ground response and support requirements are closely related to the magnitude and orientation of the stress changes, as well as the local geology. This paper presents the monitoring results of gateroad response and support performance at two longwall mines at a 180-m and 600-m depth of *** the first mine, a three-entry gateroad layout was used. The second mine used a four-entry, yieldabutment-yield gateroad pillar system. Local ground deformation and support response were monitored at both sites. The monitoring period started during the development stage and continued during first panel retreat and up to second panel retreat. The two data sets were used to compare the response of the entries in two very different geotechnical settings and different gateroad layouts. The monitoring results were used to validate numerical models that simulate the loading conditions and entry response for these widely differing conditions. The validated models were used to compare the load path and ground response at the two mines. This paper demonstrates the potential for numerical models to assist mine engineers in optimizing longwall layouts and gateroad support systems.

关键词： Coal mining Longwall Gateroad Support Numerical models

Assessing support alternatives for longwall gateroads subject to changing stress

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International Journal of Mining Science and Technology 2021年第1期31卷 103-110页

作者： Gabriel S.Esterhuizen I.Berk Tulu Dave f.Gearhart heather Dougherty Mark Van Dyke National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA West Virginia University MorgantownWV 26506USA

Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted *** stress changes can result in significant deformation of the entries that may include roof sag,rib dilation,and floor *** operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall *** paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support *** research included monitoring of ground and support interaction at several operating longwall mines in the U.S.,analysis and calibration of numerical models that adequately represent the bedded rock mass,and observation of the support systems and their response to changes in *** models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic *** research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress *** information is then used to assess the ability of support systems to maintain the stability of the *** application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof *** method is shown to produce realistic estimates of gateroad entry stability and support performance,allowing alternative support systems to be assessed during the design and planning stage of longwall operations.

关键词： Longwall Gateroad Support design Coal Standing support

Building Momentum to Realign Incentives to Support Open Science

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Data Intelligence 2021年第1期3卷 71-78页

作者： heather Joseph SPARC(Scholarly Publishing and Academic Resources Coalition) Washington DC 20036USA

The COVID-19 pandemic highlights the urgent need to strengthen global scientific collaboration,and to ensure the fundamental right to universal access to scientific progress and its *** Science(OS)is central to achieving these *** aims to make science accessible,transparent,and effective by providing barrier-free access to scientific publications,data,and infrastructures,along with open software,Open Educational Resources,and open *** also promotes public trust in science at a time when it has never been more important to do *** the past decade,momentum towards the widespread adoption of OS practices has been primarily driven by declarations(e.g.,DORA,the Leiden Manifesto).These serve an important role,but for OS to truly take root,researchers also must be fully incentivized and rewarded for its *** requires research funders and academic leaders to take the lead in collaborating,with researchers in designing,and implementing new incentive structures,and to actively work to socialize these throughout the research *** US National Academies of Science,Engineering,and Medicine(NASEM)Roundtable on Aligning Research Incentives for OS is one such *** paper examines the strategy behind convening the Roundtable,its current participant makeup,focus,and *** also explores how this approach might be expanded and adapted throughout the global OS community.

关键词： Research assessment Incentives Open Science NASEM Roundtable

Scattering and diffraction of plane P-waves in a 2-D elastic half-space Ⅱ：shallow arbitrary shaped canyon

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Earthquake Engineering and Engineering Vibration 2017年第3期16卷 459-485页

作者： heather P.Brandow Vincent Lee Civil and Environmental Engineering University of Southern California Los Angeles 90089 United States

Scattering and Diffraction of elastic in-plane P-and SV-waves by a surface topography such as an elastic canyon at the surface of a half-space is a classical problem which has been studied by earthquake engineers and strong-motion seismologists for over forty years. The case of out-of-plane SH waves on the same elastic canyon that is semi-circular in shape on the half-space surface is the first such problem that was solved by analytic closed form solutions over forty years ago by Trifunac. The corresponding case of in-plane P-and SV-waves on the same circular canyon is a much more complicated problem because, the in-plane P-and SV-scattered waves have different wave speeds and together they must have zero normal and shear stresses at the half-space surface. It is not until recently in 2014 that analytic solution for such problem is found by the author in the work of Lee and Liu. This paper uses the technique of Lee and Liu of defining these stress-free scattered waves to solve the problem of the scattered and diffraction of these in-plane waves on an almost-circular surface canyon that is arbitrary in shape.

关键词： diffraction elastic P-waves SV-waves weighted-residual method arbitrary-shaped canyon

Canine on the Couch:The New Canary in the Coal Mine for Environmental Health Research

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Environment & Health 2024年第8期2卷 517-529页

作者： Catherine f.Wise Matthew Breen heather M.Stapleton Nicholas School of the Environment Duke UniversityDurhamNorth Carolina 27708United States Duke Cancer Institute DurhamNorth Carolina 27710United States Department of Molecular Biomedical Sciences College of Veterinary MedicineNorth Carolina State University1060 William Moore DriveRaleighNorth Carolina 27607United States Comparative Medicine Institute North Carolina State UniversityRaleighNorth Carolina 27607United States Center for Human Health and the Environment North Carolina State UniversityRaleighNorth Carolina 27607United States

Human health is intimately connected and tied to the health of our environment and ecosystem,with only a very small fraction of the risk for chronic diseases explained by genetics *** animals are prone to disease types that are shared with people,including cancers and endocrine disorders,reinforcing the thought that environmental factors contribute to the risks for chronic *** factors include air and water pollution and the built *** such,there is increasing interest in pursuing research with companion animals,and specifically dogs,as sentinel species to inform comparative health assessments and identify risk factors for *** the canine diseases for which environmental exposure research has been published,cancers have received the most *** review summarizes two main aspects of this comparative approach:(1)cancers that occur in dogs and which are similar to humans and(2)research investigating environmental exposures and health outcomes in *** goal of this review is to highlight the diverse conditions in which pet dogs may provide unique perspectives and advantages to examine relationships between environmental exposures and health outcomes,with an emphasis on chemical pollution and ***,this review seeks to raise awareness and stimulate discussion around the best practices for the use of companion animals as environmental health sentinels.

关键词： sentinels dogs environmental health comparative oncology cancer alternative models environmental exposure

Bile acid signaling and biliary functions

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Acta Pharmaceutica Sinica B 2015年第2期5卷 123-128页

作者： Hannah Jones Gianfranco Alpini heather francis Baylor Scott & White Digestive Disease Research Center Division Research Central Texas Veterans Health Care System Department of Medicine Texas A&M University

This review focuses on various components of bile acid signaling in relation to cholangiocytes. Their roles as targets for potential therapies for cholangiopathies are also explored. While many factors are involved in these complex signaling pathways, this review emphasizes the roles of transmembrane G protein coupled receptor(TGR5), farnesoid X receptor(fXR), ursodeoxycholic acid(UDCA) and the bicarbonate umbrella. following a general background on cholangiocytes and bile acids,we will expand the review and include sections that are most recently known(within 5–7 years) regarding the field of bile acid signaling and cholangiocyte function. These findings all demonstrate that bile acids influence biliary functions which can, in turn, regulate the cholangiocyte response during pathological events.

关键词： Bile acids Cholangiocytes Receptors Signaling

A review of solar type Ⅲ radio bursts

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Research in Astronomy and Astrophysics 2014年第7期14卷 773-804页

作者： Hamish Andrew Sinclair Reid heather Ratcliffe SUPA School of Physics & Astronomy University of GlasgowG12 8QQUnited Kingdom Centre for Space Fusion and AstrophysicsDepartment of PhysicsUniversity of WarwickCV47ALUnited Kingdom

Solar type III radio bursts are an important diagnostic tool in the understanding of solar accelerated electron beams. They are a signature of propagating beams of nonthermal electrons in the solar atmosphere and the solar system. Consequently, they provide information on electron acceleration and transport, and the conditions of the background ambient plasma they travel through. We review the observational properties of type III bursts with an emphasis on recent results and how each property can help identify attributes of electron beams and the ambient background plasma. We also review some of the theoretical aspects of type III radio bursts and cover a number of numerical efforts that simulate electron beam transport through the solar corona and the heliosphere.

关键词： Sun: flares -- Sun: radio radiation -- Sun: X-rays gamma rays -- Sun:particle emission