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Assessment of digital image correlation method in determining large scale cemented rockfill strains

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International Journal of Mining Science and Technology 2019年第5期29卷 771-776页

作者： Bob A.Lingga derek B.Apel Mohammadali Sepehri Yuanyuan Pu School of Mining and Petroleum Engineering University of AlbertaEdmonton T6G 2W2Canada

A conventional contact method(using linear transducers)and a non-contact method are deployed to measure the axial and lateral deformations of large scale cylindrical cemented rockfill *** works incorporating two pinhole cameras to create one stereovision by digital image correlation shows that the non-contact method is as reliable for testing large cylindrical specimens as measurements done by using linear variable displacement transformer and string *** this particular large specimen,the experiment resulted in the acceptable mean difference between lateral strain using both methods is 5.1 percent,and 14.5 percent for the axial *** occurrence is inevitable due to the heterogeneity of the concrete system and the placement of the monitoring point in digital image correlation method,although the comparison of stress-strain relationship in both methods still indicates a *** on the results of the present experiments,the authors recommend the noncontact method for a detailed investigation of the material behavior during the uniaxial compressive strength *** field strain measurement enables this digital method to examine local strains near cracks at any point,a very useful tool for studying material deformation behavior.

关键词： Experimental testing Cemented rockfill Digital image correlation Strain measurement Mine backfill

The effect of rosin acid on hydrodeoxygenation of fatty acid

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Journal of Energy Chemistry 2019年第1期28卷 85-94页

作者： Houman Ojagh derek Creaser Muhammad Abdus Salam Eva Lind Grennfelt Louise Olsson Competence Centre for Catalysis Chemical Engineering Chalmers University of Technology Preem AB

In this study, inhibition of tall oil fatty acid hydrodeoxygenation(HDO) activity due to addition of rosin acid over sulfided Ni Mo/Al_2O_3 was investigated. Oleic acid and abietic acid were used as model compounds for fatty acid and rosin acid respectively in tall oil. After completion of each HDO experiment,the Ni Mo catalysts were recovered and used again under the same conditions. The results showed that the oleic acid HDO activity of sulfided catalysts was inhibited by addition of abietic acid due to competitive adsorption and increased coke deposition. The rate of carbon deposition on the catalysts increased when abietic acid was added to oleic acid feed. Moreover, the coke was in a more advanced form with higher stability for the catalysts exposed to both oleic acid and abietic acid. Furthermore, a clear correlation between the rate of coke formation and concentration of abietic acid was observed.

关键词： Rosin acid Carbon deposition Coke formation Hydrodeoxygenation(HDO) Inhibition

Coupled hydro-mechanical evolution of fracture permeability in sand injectite intrusions

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第4期12卷 742-751页

作者： Quan Gan derek Elsworth Yixin Zhao Antonio Grippa Andrew Hurst School of Geosciences University of AberdeenAberdeenUK State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyBeijingChina Department of Energy and Mineral Engineering EMS Energy Institute and G3 CenterPennsylvania State UniversityUniversity ParkPAUSA

Sandstone“injectite”intrusions are generally developed by the fluidization of weakly cemented sandstones and their subsequent injection into fractured *** this work,a continuum coupled hydromechanical model TOUGH-FLAC3D is applied to simulate the discrete fracture network in large-scale sand injectite complexes.A sand production constitutive model is incorporated to consider the formation of sand through plastic deformation and its influence on evolution of fracture *** in the fluidized sand slurry drives the injection with sand dikes intruded upwards,typically into previously low permeability“tight”mudstone *** contrast in poroelastic properties of the underlying weak sandstone and overlying injectite receptor directly affects the evolution of fracture aperture both during and after *** drainage into the unconsolidated matrix may reduce the extent of fracture aperture growth,through the formation of shear *** results of this work have broad implications related to the emplacement of sandstone intrusions and subsequent hydrocarbon accumulation,maturation and then production.

关键词： Sandstone intrusions Fracture permeability Sand fluidization Hydro-mechanical coupling

Soluble Triggering Receptor Expressed on Myeloid Cells-1 and Inflammatory Markers in Colorectal Cancer Surgery： A Prospective Cohort Study

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Chinese Medical Journal 2017年第22期130卷 2691-2696页

作者： Lovorka derek Drazen Servis Adriana Unic Department of Clinical Chemistry Sestre Milosrdnice University Hospital Center Zagreb 10000 Croatia Department of General and Abdominal Surgery St. Anna Hospital Sulzbach-Rosenberg 92237 Germany

Background： Major abdominal surgery, including colorectal cancer （CRC） surgery, leads to systemic inflammatory response syndrome that can be detected and monitored with inflammatory markers testing. The aims of the study were to evaluate the usefulness of soluble triggering receptor expressed on myeloid cells-l （sTREM-1 ）, interleukin-6 （IL-6）, procalcitonin （PCT）, and C-reactive protein （CRP） in following the inflammatory response in CRC surgery and postoperative period, as well as to determine if duration of the surgery and the time that the colon has been opened during the surgery （open colon time [OCT]） refect a larger surgical stress through inflammatory markers rise. Methods： The study included 20 patients who underwent CRC surgery and 19 healthy volunteers from June 2011 to September 2012. We determined inflammatory markers 1 day before surgery （T0）, 24 h （T1）, 48 h （T2）, and 7 days after the surgery （T3）. All statistical analyses were calculated using MedCalc Statistical Software version 14.8.1 （MedCalc Software bvba, Ostend, Belgium）. Results： Concentrations ofCRP, PCT, and I L-6 in all measurement times were statistically different and sTREM- 1 did not yield statistical significance. A weak positive correlation was/bund between l L-6 in T 1 and T2 with the duration of the surgery （T 1 ： r= 0.4060, P 〈 0.0001 ; T2：r =0.3430, P〈0.0001）andOCT（T1：r= 0.3640, P〈0.0001,T2：r=0.3430, P〈0.0001）.AweakpositivecorrelationbetweenCRP in T2 and OCT （r = 0.4210, P 〈 0.0001 ） was also found. The interconnectivity of tested parameters showed a weak positive correlation between CRP and IL-6 in T1 （r= 0.3680; P 〈 0.0001 ）, moderate positive correlation in T2 （r = 0.6770; P 〈 0.0001）, and a strong positive correlation in T3 （r = 0.8651; P 〈 0.0001）. Conclusions： CRP, IL-6, and PCT were shown to be reliable for postoperative monitoring. Simultaneous determination of CRP and IL-6 might not be useful as they follow similar kinetics, sTREM- 1 might not be useful in CRC postoperat

关键词： Acute-phase Proteins Colorectal Cancer Surgery Soluble Triggering Receptor Expressed on Myeloid Cells-1

Rapid decompression and desorption induced energetic failure in coal

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Journal of Rock Mechanics and Geotechnical Engineering 2015年第3期7卷 345-350页

作者： Shugang Wang derek Elsworth Jishan Liu Department of Energy and Mineral Engineering EMS Energy Institute and G~3 Center Pennsylvania State University School of Mechanical and Chemical Engineering University of Western Australia

In this study, laboratory experiments are conducted to investigate the rapid decompression and desorption induced energetic failure in coal using a shock tube apparatus. Coal specimens are recovered from Colorado at a depth of 610 m. The coal specimens are saturated with the strong sorbing gas CO2 for a certain period and then the rupture disc is suddenly broken on top of the shock tube to generate a shock wave propagating upwards and a rarefaction wave propagating downwards through the *** rapid decompression and desorption has the potential to cause energetic fragmentation in *** types of behaviors in coal after rapid decompression are found, i.e. degassing without fragmentation, horizontal fragmentation, and vertical fragmentation. We speculate that the characteristics of fracture network（e.g. aperture, spacing, orientation and stiffness） and gas desorption play a role in this dynamic event as coal can be considered as a dual porosity, dual permeability, dual stiffness sorbing medium. This study has important implications in understanding energetic failure process in underground coal mines such as coal gas outbursts.

关键词： Rapid decompression Gas desorption Energetic failure Gas outburst Coal

Structural analysis of rubble-pile asteroids applied to collisional evolution

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Astrodynamics 2017年第1期1卷 57-69页

作者： Yang Yu derek CRichardson Patrick Michel School of Aeronautic Science and Technology Beihang UniversityBeijing 100191China Department of Astronomy University of MarylandCollege Park MD 20740-2421USA Observatoire de la Cote d'Azur UMR 7293 Lagrange/CNRS06304 Nice Cedex 4France

Solar system small bodies come in a wide variety of shapes and sizes,which are achieved following very individual evolutional paths through billions of ***,some common mechanisms can still be found during these processes,e.g.,rubble-pile asteroids tend towards fluid equilibrium as they are reshaped by external *** paper focuses on the reshaping process of rubble-pile asteroids driven by meteorite impacts.A mesoscale cluster of solid spheres is employed as the principal model for a rubble-pile asteroid,for which little is actually known about their interior *** take this simple model as a rough guide to the qualitative aspects of the reshaping processes,and it can reveal,to some degree,the inner workings of rubble-pile *** our study,numerous possible equilibrium configurations are obtained via Monte Carlo simulation,and the structural stability of these configurations is determined via eigen analysis of the geometric *** eigen decomposition reveals a connection between the cluster’s reactions and the types of external *** simulations are performed to verify the analytical *** gravitational N-body code pkdgrav is used to mimic the responses of the cluster under intermittent non-dispersive *** statistically confirm that the stability index I S,the total gravitational potential P G,and the volume of inertia ellipsoid V E show consistent tendency of variation.A common regime is found in which the clusters tend towards crystallization under intermittent impacts,i.e.,only the configurations with high structural stability survive under the external *** results suggest the trivial non-disruptive impacts might play an important role in the rearrangement of the constituent blocks,which may strengthen these rubble piles and help to build a robust structure under impacts of similar *** final part of this study consists of systematic simulations over two parameters

关键词： asteroids interior structure geological processes N-body simulations gravitational aggregates meteorite impacts

Primary care physicians'knowledge,attitude and perception towards homosexuality in Singapore

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Global Health Journal 2021年第4期5卷 209-214页

作者： derek Lim Seng Bin Ang Kandang Kerbau Women’s and Children’s Hospital 100 Bukit Timah Road Singapore

Aims:This study aim to gain insights into attitudes,acceptance and knowledge levels among family physicians toward homosexual people,which are important as they may affect care among this at-risk ***:An anonymized self-administered questionnaire in English was posted with the assistance of the College of Family Physicians Singapore in February 2015 to its 1529 members with self-addressed,pre-stamped envelopes for *** questionnaire included demographic questions such as age group,gender,religion,ethnicity,marital status and place of *** and scales that measured attitude,acceptance,knowledge and perception of colleagues who are homosexual were also included in the ***:451 responses(29.5%)were obtained,of which 441 were valid(28.84%).About 52.8%of participants were found to have negative,8.9%neutral and 38.3%positive attitudes toward ***(75.6%)were accepting of homosexuals,with 9.3%neutral and 15.1%not *** levels were poor,with a mean score of 6.9 out of a maximum of 13.A strong correlation was found between the attitudes towards lesbians and gay men(ATLG)and acceptance of homosexuals scales(r=0.69,P<0.001),with moderate correlations between acceptance and knowledge(r=0.54,P<0.001)and ATLG and Knowledge(r=0.54,P<0.001).Conclusion:Despite majority of family physicians having negative attitudes towards homosexuality,most are able to accept *** better education in sexual orientation in the medical educational curriculum,the increase in knowledge will lead to better care for people with homosexuality.

关键词： Attitudes Acceptance Family physician Homosexuality Knowledge Stigma Sexual orientation Singapore

CD4 and CD8 T cells mediate distinct lethal meningoencephalitis in mice challenged with Tacaribe arenavirus

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Cellular & Molecular Immunology 2017年第1期14卷 90-106页

作者： derek DC Ireland Cecilia Tami Joao Pedras-Vasconcelos Daniela Verthelyi Division of Biologics Review and Research-III Office of Biotechnology Center for Drug Evaluation and Research Food and Drug Administration Silver Spring MD 20993 USA

Neonates are at increased risk of viral encephalopathies that can result in neurological dysfunction, seizures, permanent disability and even death. The neurological damage results from the combined effect of the virus and the immune response it elicits, thus finding tools to facilitate viral clearance from central nervous system （CNS） while minimizing neuron damage remains a critical challenge. Neonatal mice inoculated intraperitoneally with Tacaribe virus （TCRV） develop seizures, hindlimb paralysis and death within 15 days of inoculation. TCRV localizes to the CNS within days of challenge, primarily infecting astrocytes in the cerebellum and brain stem. We show that infection leads to inflammation, T cell and monocyte infiltration into the cerebellar parenchyma, apoptosis of astrocytes, neuronal degeneration and loss of Purkinje cells. Infiltrating antigen-specific T cells fail to clear the virus but drive the disease, as T-cell-deficient CD3ε KO mice survive TCRV infection with minimal inflammation or clinical manifestations despite no difference in CNS viral loads in comparison with T-cell sufficient mice. CD8＋ T cells drive the pathology, which even in the absence of CD4＋ T-cell help, infiltrate the parenchyma and mediate the apoptotic loss of cerebellar astrocytes, neurodegeneration and loss of Purkinje cells resulting in loss of balance, paralysis and death. CD4＋ T cells are also pathogenic inducing gliosis and inflammation in the cerebellum and cerebrum that are associated with wasting and death several weeks after CD4＋ T-cell transfer. These data demonstrate distinct pathogenic effects of CD4＋ and CD8＋ T cells and identify them as possible therapeutic targets.

关键词： Astrocytes CD4 T cells CD8 T cells encephalitis Purkinje cells virus

Bank erosion in an Andean páramo river system: Implications for hydro-development and carbon dynamics in the neotropical Andes

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Journal of Mountain Science 2019年第2期16卷 243-255页

作者： derek J.MARTIN Christopher ELY Beverley C.WEMPLE Department of Geography and Planning Appalachian State University Department of Geography University of Vermont

The páramo of the Northern Andes provide critically important ecosystem services to the Northern Andean region in the form of water provisioning and carbon sequestration, both of which are a result of the páramo?s organic-rich soils. Little is known, however, about the hydro-geomorphic characteristics of the rivers that drain these ecosystems. With impending plans for widespread hydro-development and increasing implementation of carbon-sequestering compensation for ecosystem services programs in the region it is imperative that we develop a thorough understanding of the hydrogeomorphic role that rivers play in this unique ecosystem. The objective of this study was to quantify bank erosion along an Amazonian headwater stream draining a small, relatively undisturbed páramo catchment to gain a better understanding of the natural erosion regime and the resulting sediment contributions from this unique ecosystem. This study implemented a combination of field, laboratory, and Geographic Information Systems techniques to quantify bank erosion rates and determine a bank erosion sediment yield from the Ningar River, a small páramo catchment(22.7 km^2) located in the eastern Andean cordillera of Ecuador. Results show that bank erosion rates range from 3.0 to ≥ 390.0 mm/yr, are highly episodic, and yield at least 487 tons of sediment annually to the Ningar River. These results imply that 1) páramo ecosystems substantially contribute to the sediment load of the Amazon River basin; 2) bank erosion is a potentially significant flux component of basin-scale carbon cycles in páramo ecosystems; and 3) hydrologic alteration campaigns(dam building) will likely critically alter these contributions and concomitantly disconnect a critical source of sediment and nutrients to downstream ecosystems.

关键词： Bank erosion Páramo Fluvial geomorphology Andes