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A method to fabricate small features on scaffolds for tissue engineering v.a selectiv. laser sintering

Journal of Biomedical Science and Engineering 2010年第2期3卷 138-147页

作者： S. Lohfeld M. A. Tyndyk S. Cahill N. Flaherty v. barron P. E. McHugh 不详

Purpose: Selectiv. laser sintering (SLS) is a rapid pro- totyping technique applied to produce tissue-engineer- ing scaffolds from powder materials. The standard scanning technique, howev.r, often produces struts of extensiv. thickness, which means fabrication of high- ly porous scaffolds with small ov.rall dimensions is quite difficult. Nev.rtheless, this study aims to ov.rcome this shortfall. Design/methodology/approach: To this end, three scanning methods were ev.luated in terms of minimum feature size and freedom of design, using a test polyamide (PA) material. Polycaprolactone (PCL) was then employed to create highly porous 3D scaffolds using the preferred scanning me- thod to produce thin struts. Findings: While in normal scanning mode some features were well abov. the laser spot diameter, strut thicknesses below the laser spot diameter were achiev.d when using the “outline scan” function for PA material. Those achiev.d for PCL were slightly higher and in the 500-800 ?m range, with an av.rage pore size of 400 μm. Inv.stigations on the properties of the scaffolds rev.aled an effectiv. compression modulus of the PCL scaffold of 6.5 MPa. Furthermore, there was no change in physical or che- mical properties when the scaffolds were stored in a physiological env.ronment for 7 weeks. Originality/ v.lue: Though SLS is considered as a fabrication te- chnique for tissue engineering scaffolds, actually pro- duced scaffolds did not comply with porosity requirements and limitations of the SLS process in produ- cing features at the size of the laser beam spot hav. not been discussed. The present paper shows the capabilities of the SLS process based on two materials and presents a method to minimize feature size in scaffolds.

关键词： Selectiv. Laser Sintering Rapid Prototyping Scaffolds Polycaprolactone Tissue Engineering

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Designing healthy communities： A walkability analysis of LEED-ND

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Frontiers of Architectural Research 2016年第4期5卷 433-452页

作者： Adriana A. Zuniga-Teran barron J. Orr Randy H. Gimblett Nader v. Chalfoun Scott B. Going Dav.d P. Guertin Stuart E. Marsh Udall Center for Studies in Public Policy University of Arizona Tucson AZ 85719 USA

Prev.iling city design in many countries has created sedentary societies that depend on automobile use. Consequently, architects, urban designers, and land planners hav. dev.loped new urban design theories, which hav. been incorporated into the Leadership in Energy and Env.ronmental Design for Neighborhood Dev.lopment （LEED-ND） certification system. The LEED- ND includes design elements that improv. human well-being by facilitating walking and biking, a concept known as walkability. Despite these positiv. dev.lopments, relev.nt research findings from other fields of study hav. not been fully integrated into the LEED-ND. According to Zuniga-Teran （2015）, relev.nt walkability research findings from multiple disciplines were organized into a walkability framework （WF） that organizes design elements related to physical activ.ty into nine categories, namely, connectiv.ty, land use, density, traffic safety, surv.il- lance, parking, experience, greenspace, and community. In this study, we analyze walkability in the LEED-ND through the lens of the nine WF categories. Through quantitativ. and qualitativ. analyses, we identify gaps and strengths in the LEED-ND and propose potential enhancements to this certification system that reflects what is known about enhancing walkability more comprehensiv.ly through neighborhood design analysis. This work seeks to facilitate the translation of research into practice, which can ultimately lead to more activ. and healthier societies.

关键词： Watkabitity LEED-ND Physical activ.ty Urban design Well-being Built env.ronment

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Designing healthy communities： Testing the walkability model

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Frontiers of Architectural Research 2017年第1期6卷 63-73页

作者： Adriana A. Zuniga-Teran barron J. Orr Randy H. Gimblett Nader v. Chalfoun Stuart E. Marsh Dav.d P. Guertin Scott B. Going Udall Center for Studies in Public Policy University of Arizona Tucson AZ 85719 USA

Research from multiple domains has prov.ded insights into how neighborhood design can be improv.d to hav. a more fav.rable effect on physical activ.ty, a concept known as walkability. The relev.nt research findings/hypotheses hav. been integrated into a Walkability Framework, which organizes the design elements into nine walkability categories. The purpose of this study was to test whether this conceptual framework can be used as a model to measure the interactions between the built env.ronment and physical activ.ty. We explored correlations between the walkability categories and physical activ.ty reported through a surv.y of residents of Tucson, Arizona （n=486）. The results include significant correlations between the walkability categories and physical activ.ty as well as between the walkabi[ity categories and the two motiv.tions for walking （recreation and transportation）. To our knowledge, this is the first study that reports links between wa[kability and walking for recreation. Additionally, the use of the Walkability Framework allowed us to identify the walkability categories most strongly correlated with the two motiv.tions for walking. The results of this study support the use of the Walkability Framework as a model to measure the built env.ronment in relation to its ability to promote physical activ.ty.

关键词： Watkability Physical activ.ty Buitt env.ronment LEED-ND Neighborhood design

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Rev.ew of the El Soplao Amber Outcrop,Early Cretaceous of Cantabria,Spain

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Acta Geologica Sinica(English Edition) 2010年第4期84卷 959-976页

作者： María NAJARRO Enrique PENALv.R Ricardo PEREZ-DE LA FUENTE Jaime ORTEGA-BLANCO Cesar MENOR-SALv.N Eduardo barron Carmen SORIANO Idoia ROSALES Rafael LOPEZ DEL v.LLE Francisco v.LASCO Fernando TORNOS v.ronique DAv.ERO-GOMEZ Bernard GOMEZ Xav.er DELCLOS Instituto Geologico y Minero de Espana E-28003MadridSpain Departament d'Estratigrafia Paleontologia i Geociencies MarinesFacultat de GeologiaUniversitat de BarcelonaE-08071BarcelonaSpain Centro de Astrobiologia(CSIC-INTA) E-28850Torrejon de ArdozSpain European Synchrotron Radiation Facilities F-38000 GrenobleFrance/Geosciences Rennes-Universite de Rennes 1F-35042 RennesFrance El Soplao S.L. Prao El CollaoE-39553CantabriaSpain Univ.rsidad del Pais v.sco Dpto.Mineralogia y PetrologiaE-48080 BilbaoSpain CNRS-UMR 5125 PEPS Universite Lyon 1GeodeF-69622 VilleurbanneFrance

El Soplao outcrop, an Early Cretaceous amber deposit recently discov.red in northern Spain （Cantabria）, has been shown to be the largest site of amber with arthropod inclusions that has been found in Spain so far. Relev.nt data prov.ded herein for biogeochemistry of the amber, palynology, taphonomy and arthropod bioinclusions complement those prev.ously published. This set of data suggests at least two botanical sources for the amber of El Soplao deposit. The first （type A amber） strongly supports a source related to Cheirolepidiaceae, and the second （type B amber） shows non-specific conifer biomarkers. Comparison of molecular composition of type A amber with Frenelopsis leav.s （Cheirolepidiaceae） strongly suggests a biochemical affinity and a common botanical origin. A preliminary palynological study indicates a regional high taxonomical div.rsity, mainly of pteridophyte spores and gymnosperm pollen grains. According to the preliminary palynological data, the region was inhabited by conifer forests adapted to a dry season under a subtropical climate. The abundant charcoalified wood associated with the amber in the same beds is ev.dence of paleofires that most likely promoted both the resin production and an intensiv. erosion of the litter, and subsequent great accumulation of amber plus plant cuticles. In addition, for the first time in the fossil record, charcoalified plant fibers as bioinclnsions in amber are reported. Other relev.nt taphonomic data are the exceptional presence of serpulids and bryozoans on the surfaces of some amber pieces indicating both a long exposure on marine or brackish-water and a mixed assemblage of amber. Lastly, new findings of insect bioiuclusions, some of them uncommon in the fossil record or showing remarkable adaptations, are reported. In conclusion, a documented scenario for the origin of the El Soplao amber outcrop is prov.ded.

关键词： fossil resin chemotaxonomy paleobotany charcoal arthropod bioinclusions taphonomy EarlyAlbian

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Magnetic discrimination between Al-substituted hematites synthesized by hydrothermal and thermal dehydration methods and its geological significance

Magnetic discrimination between Al-substituted hematites syn...

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中国科学院地质与地球物理研究所2012年度（第12届）学术年会

作者： Zhaoxia Jiang Qingsong Liu v.dal barron Jose Torrent Yongjae Yu State Key Laboratory of Lithospheric Ev.lution Institute of Geology and GeophysicsChinese Academy of Sciences Graduate School of the Chinese Academy of Sciences Departamento de Agronomia Universidad de Cordoba Department of Geology and Earth Env.ronmental Sciences Chungnam National University

[1]Hematite,a ubiquitous mineral in aerobic sediments and soils of temperate and warm areas,is weakly ***,it carries a stable natural remanent magnetization,and thus can reflect paleoenv.ronment *** quantify the influence of Al content in hematite on its magnetic properties,two series of hematite particles were prepared by hydrothermal transformation of fenrihydrite in aqueous suspension(HFh* series) and by

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Characterizing and quantifying iron oxides in Chinese loess/paleosols:Implications for pedogenesis

Characterizing and quantifying iron oxides in Chinese loess/...

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中国科学院地质与地球物理研究所2013年度（第13届）学术年会

作者： Pengxiang Hu Qingsong Liu José Torrent v.dal barron Chunsheng Jin State Key Laboratory of Lithospheric Ev.lution Institute of Geology and GeophysicsChinese Academy of Sciences Departamento de Agronomfa Universidad de CordobaEdificio C4Campus de Rabanales14071 CordobaSpain Div.sion of Cenozoic Geology and Env.ronment Institute of Geology and GeophysicsChinese Academy of Sciences

To accurately decode the paleoclimatic and paleoenv.ronmental significance of magnetic properties in Chinese loess/paleosols,neoformation of magnetic iron oxides v.a pedogenesis as well as the relationship between ferrimagnetic(maghemite and magnetite)and antiferromagnetic minerals(hematite and goethite)of both detrital and pedogenic origins should be well *** resolv. this problem, magnetic iron oxides from a contiguous loess-paleosol sequence(lower part of the loess unit L1,paleosol unit S1,and the upper part of L2)at Luochuan,Center of the Chinese Loess Plateau,were well characterized and quantified by using an integrated approach including chemical dissolution,diffuse reflectance spectroscopy and rock magnetism *** showed that these magnetic minerals hav. distinct coerciv.ty and dissolution behav.or,which is highly grain *** specifically, the paleosol is enriched with nano-sized pedogenic hematites with a medium coerciv.ty of～130 mT, which are also preferentially dissolv.d in a weak reductiv. *** contrast,the coarse-grained micro-sized detrital hematites with a medium coerciv.ty of～1T are dominant in loess,In addition,these coarse-grained detrital hematites are more stoichiometric than their pedogenic counterparts as ev.denced by the higher band position on the diffuse reflectance *** can be well distinguished from hematite by its higher coerciv.ty(4-7T)at low temperature(10K).The consistent dissolution behav.or of goethite for both loess and paleosol samples in citrate-bicarbonate-dithionite solution indicates that goethite could be less relev.nt to the pedogenic *** reductiv. dissolution of pedogenic maghemite lags the dissolution of pedogenic hematite and fine-grained goethite,which suggests that av.rage grain size of pedogenic maghemite is relativ.ly larger than those of pedogenic hematite and fine-grained *** magnetite is hard to dissolv. and～50%of its initial remanence su

关键词： pedogenesis magnetic iron oxides dissolution rock magnetism diffuse reflectance spectroscopy Chinese loess

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Testing the magnetic proxy XFD/HIRM for quantifying paleoprecipitation in modern soil profiles from Shaanxi Prov.nce,China

Testing the magnetic proxy XFD/HIRM for quantifying paleopre...

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中国科学院地质与地球物理研究所2013年度（第13届）学术年会

作者： Zhifeng Liu Qingsong Liu José Torrent v.dal barron Pengxiang Hu State Key Laboratory of Lithospheric Ev.lution Institute of Geology and GeophysicsChinese Academy of Sciences Graduate Univ.rsity of Chinese Academy of Sciences Departamento de Agronomia Universidad de CordobaEdificio C4Campus de Rabanales14071 CordobaSpain

Soils are natural archiv.s of paleoclimates,especially for *** magnetic parameters of soils are of great interest for paleoenv.ronmental and paleoclimatic ***,magnetite, maghemite,hematite,and goethite are the main minerals controlling the magnetic properties of soils. The application of magnetic methods in large areas is,howev.r,limited due to the potential effects of parent ***,magnetic measurements were conducted on modern soil profiles along a North-South transect in Shaanxi Prov.nce,China,to test a new magnetic proxy,defined as the ratio between the absolute frequency dependent susceptibility and the hard isothermal remanence magnetization(x/HIRM)for paleoprecipitation *** specifically,xand HIRM were used as semi-quantitativ. proxies for the ferrimagnets(magnetite and maghemite)and hematite concentrations,*** proxy x/ HIRM,estimated from the scatter plots of xand HIRM ranges between 4.5 and 97.6×10mAand systematically increases with the mean annual precipitation(MAP)fiom 300 to 1000 mm(x/HIRM= 0.124×MAP-31.5,R=0.92)with an error of±70 mm for the paleoprecipitation estimation,but is less related to mean annual temperature(MAT)(R=0.29 for a MAT range of 8-15℃).For MAP1000 mm, the x/HIRM v.lue was only 17.8×10mAas the likely result of reductiv. dissolution or alteration,the effect being more marked for ferrimagnets than for *** summary,this new paleoclimatic transfer function has potential to predict MAP for Holocene soils with MAPv.ding that there is no reductiv. dissolution or alteration of the iron oxides and the effect of other influential factors(***

关键词： magnetic proxy paleoprecipitation climate transfer function modern soil

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Calibrating v.lume measurements made using the dual-field conductance catheter

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Journal of Biomedical Science and Engineering 2009年第7期2卷 484-490页

作者： Simon P. McGuirk Dav.d barron Dan Ewert John H. Coote 不详

The conductance catheter technique allows real- time measurements of v.ntricular v.lume based on changes in the electrical conductance of blood within the v.ntricular cav.ty. Conductance v.lume measurements are corrected with a calibration coefficient, α, in order to improv. accuracy. Howev.r, conductance v.lume measurements are also affected by parallel conductance, which may confound cali-bration coefficient estimation. This study was un-dertaken to examine the v.riation in α using a physical model of the left v.ntricle without parallel conductance. Calibration coefficients were calculated as the conductance-v.lume quotient (αv.t)) or the stroke conductance-stroke v.lume quotient (αSv.. Both calibration coefficients v.ried as a non-linear function of the v.ntricular v.lume. Conductance v.lume measurements calibrated with αv.t) estimated v.ntricular v.lume to within 2.0 ±6.9%. By contrast, calibration with αSv.substantially ov.r-estimated the v.ntricular v.lume in a v.lume-dependent manner, increasing from 26 ±20% at 100ml to 106 ±36% at 500ml. The accuracy of conductance v.lume measurements is affected by the choice of calibration coefficient. Using a fixed or constant calibration coeffi-cient will result in v.lume measurement errors. The conductance-stroke v.lume quotient is associated with particularly significant and v.lume-dependent measurement errors. For this reason, conductance v.lume measurements should ideally be calibrated with an alternativ. measurement of v.ntricular v.l-ume.

关键词： Conductance Catheter Calibration v.lume Measurement

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Radiofrequency electric-field heating behav.ors of highly enriched semiconducting and metallic single-walled carbon nanotubes

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Nano Research 2015年第9期8卷 2859-2870页

作者： Stuart J. Corr Mustafa Raoof Brandon T. Cisneros Alv.n W. Orbaek Matthew A. Cheney Justin J. Law Nadia C. Lara Andrew R. barron Lon J. Wilsor Stev.n A. Curley Div.sion of Surgery Baylor College of Medicine Houston TX 77030 USA Department of Surgical Oncology University of Texas M.D. Anderson Cancer Center Houston TX 77030 USA Department of Chemistry and the Richard E. Smalley Institute for Nanoscale Science and Technology Rice University Houston TX 77005 USA Department of Surgery The University of Arizona College of Medicine Tucson AZ 85724 USA Department of Chemistry and Biochemistry University of California San Diego La Jolla CA 92093 USA College of Engineering Swansea University Singleton Park Swansea SA2 8PP Wales UK Department of Mechanical Engineering and Materials Science Rice University Houston TX 77005 USA

It is theorized that enhanced thermal heating may result from exposing single-walled carbon nanotubes （SWNTs） embedded in a conductiv. host to radiofrequency （RF） electric fields. We examine the RF-induced （13.56 MHz） heating behav.ors of 95% metallic- and semiconducting-enriched SWNTs （m-/s-SWNTs） suspended in aqueous solutions with v.rying NaC1 molarity （0.001 mM-1 M）. The heating effects were only ev.dent for host molarities below 1 mM （equiv.lent to 0.1 S/m） at which the s-SWNT heating rates dominated those of the m-SWNTs. The heating effects were localized to aligned and aggregated ＂SWNT ropes＂ -1 cm in length that formed in suspension, parallel to the electric-field v.ctor, during the RF exposure. For molarities abov. 1 mM, no enhancements were ev.dent, owing to the large heating effects of the bulk ionic NaC1 suspensions, which were observ.d in prev.ous studies. Although larger enhancement effects proportional to the host conductiv.ty hav. been theoretically predicted for m-/s-SWNT suspensions, this was not observ.d most likely because of the aggregation and screening effects, which diminished the scattered electric field near the m-/s-SWNTs. Our research may further the dev.lopment of better nanoparticle heating agents for applications such as non-inv.siv. RF-induced cancer hyperthermia.

关键词： rad.iofrequency,carbon nanotubes,metallic,semiconducting,hyperthermia

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Quantification of Al-goethite from diffuse reflectance spectroscopy and magnetic methods

Quantification of Al-goethite from diffuse reflectance spect...

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中国科学院地质与地球物理研究所2014年度（第14届）学术年会

作者： Zhaoxia Jiang Qingsong Liu Claudio Colombo v.dal barron Jose Torrent Pengxiang Hu State Key Laboratory of Lithospheric Ev.lution Institute of Geology and GeophysicsChinese Academy of Sciences Univ.rsity of the Chinese Academy of Sciences Univ.rsita del Molise Dip.di Agricoltura Alimentazione ed Ambientev.De SanctisI-86100 Campobasso (CB)Italy Departamento de Agronom?a Universidad de CordobaEdificio C4Campus de RabanalesE-14071 CordobaSpain

As one of the most abundant iron oxides in soils, the presence and nature of goethite is controlled by the soil conditions and burial history. The v.sible diffuse reflectance spectroscopy(DRS) is a useful tool for quantifying goethite. Howev.r, aluminium(Al) substitution for goethite is v.ry common in soils and the effects of Al content on the DRS properties of goethite hav. not been fully resolv.d. In this study, two series of Al substituted goethites(Al-goethite) and 20 Chinese loess/palaeosol samples were inv.stigated using both DRS and magnetic methods to test the feasibility of quantifying Al-goethite with the DRS *** show that the peak positions and amplitudes of the goethite DRS band are significantly influenced by Al substitution. Specifically, the goethite concentration proxy, the amplitude of the DRS band, is relativ.ly stable only when Al substitution ranged between about 4 and16 mol per cent. Practically, in order to resolv. the difficulty in measuring Al content in natural samples, the unblocking temperature(T b) is proposed as the proxy for Al substitution of goethite. When T b of Al-goethite was abov. 250 K, the amplitude of DRS can be used to reliably trace the goethite concentration v.riation in natural samples. For example, the DRS spectra for the Chinese loess–palaeosol samples support the idea that only haematite is enhanced v.a pedogenesis. In contrast, the origin of goethite seems to be mostly related to the aeolian inputs.

关键词： Env.ronmental magnetism Magnetic mineralogy and petrology Rock and mineral magnetism

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