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Complex interplay between formation routes and natural organic matter modification controls capabilities of C_(60)nanoparticles(nC_(60)) to accumulate organic contaminants

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Journal of Environmental Sciences 2017年第1期29卷 315-323页

作者： Lei Hou john d.Fortner Ximeng Wang Chengdong Zhang Lilin Wang Wei Chen College of Environmental Science and Engineering Southwest Forestry University College of Environmental Science and Engineering Nankai University department of Energy Environmental and Chemical EngineeringWashington University in St.Louis

Accumulation of organic contaminants on fullerene nanoparticles（nC（60）） may significantly affect the risks of C（60） in the *** objective of this study was to further understand how the interplay of nC（60） formation routes and humic acid modification affects contaminant adsorption of nC（60）.Specifically,adsorption of 1,2,4,5-tetrachlorobenzene（a model nonionic,hydrophobic organic contaminant） on nC（60） was greatly affected by nC（60）formation route- the formation route significantly affected the aggregation properties of nC（60）,thus affecting the available surface area and the extent of adsorption via the pore-filling *** on whether nC（60） was formed via the ＂top-down＂ route（i.e.,sonicating C（60） powder in aqueous solution） or ＂bottom-up＂ route（i.e.,phase transfer from an organic solvent） and the type of solvent involved（toluene versus tetrahydrofuran）,modification of nC（60） with Suwannee River humic acid（SRHA） could either enhance or inhibit the adsorption affinity of nC（60）.The net effect depended on the specific way in which SRHA interacted with C（60） monomers and/or C（60） aggregates of different sizes and morphology,which determined the relative importance of enhanced adsorption from SRHA modification via preventing C（60） aggregation and inhibited adsorption through blocking available adsorption *** findings further demonstrate the complex mechanisms controlling interactions between nC（60） and organic contaminants,and may have significant implications for the life-cycle analysis and risk assessment of C（60）.

关键词： Fullerene nanoparticles Aggregation Natural organic matter Organic contaminants Adsorption

Flexible ureteroscopy:Technological advancements,current indications and outcomes in the treatment of urolithiasis

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Asian Journal of Urology 2015年第3期2卷 133-141页

作者： Husain Alenezi john d.denstedt division of Urology Department of SurgerySchulich School of Medicine&DentistryWestern UniversityLondonOntarioCanada

The last 3 decades have witnessed great improvements in the technology and clinical applications of many minimally invasive procedures in the urological *** ureteroscopy(fURS)has advanced considerably to become a widely utilized diagnostic and therapeutic tool for multiple upper urinary tract *** most common indication for fURS is the treatment of upper urinary tract stones with the aid of Holmium:Yttrium Aluminium Garnet(YAG)laser *** in endoscope technologies and operative techniques have lead to a broader application of fURS in the management of urolithiasis to include larger and more complex *** has proved to be an effective and safe procedure with few *** progression in fURS may increase its clinical applicability and supplant other procedures as the first line treatment option for urolithiasis.

关键词： Flexible ureteroscopy Urolithiasis Renal stone Endoscopy

Plant xylem hydraulics:What we understand,current research,and future challenges

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Journal of Integrative Plant Biology 2017年第6期59卷 356-389页

作者： Martin d. Venturas john S. Sperry Uwe G. Hacke department of Biology University of Utah257 S 1400ESalt Lake CityUT 84112USA department of Renewable Resources University of AlbertaEdmontonAB T6G 2E3Canada

Herein we review the current state-of-the-art of plant hydraulics in the context of plant physiology, ecology, and evolution, focusing on current and future research opportunities. We explain the physics of water transport in plants and the limits of this transport system, highlighting the relationships between xylem structure and function. We describe the great variety of techniques existing for evaluating xylem resistance to cavitation. We address several methodological issues and their connec- tion with current debates on conduit refilling and exponentially shaped vulnerability curves. We analyze the trade-offs existing between water transport safety and efficiency. We also stress how little information is available on molecular biology of cavitation and the potential role of aquaporins in conduit refilling. Finally, we draw attention to how plant hydraulic traits can be used for modeling stomatal responses to environmental variables and climate change, including drought mortality.

关键词： William J. Lucas, University of California, davis, USAReceived Jan. 10,2017 Accepted Mar. 9,2017 Online on Mar. 14,2017

Bacterial Sample Concentration and Culture Monitoring Using a PEG-Based Osmotic System with Inline Impedance and Voltammetry Measurements

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Journal of Analysis and Testing 2019年第2期3卷 166-174页

作者： Martin K.Kimani john Mwangi Edgar d.Goluch department of Chemical Engineering Northeastern UniversityBostonMA 02115USA department of Bioengineering Northeastern UniversityBostonMA 02115USA

Impedance measurements using graphite electrodes were used to detect the increase in culture medium conductivity due to bacteria growth in real time along with simultaneous voltammetric monitoring of pyocyanin *** methods were compared to conventional continuous monitoring of bacterial cultures using turbidity measurement at an optical density of 600 nm(Od600).A practical osmotic system was further designed for concentrating bacterial cultures during growth to enable earlier detection using the electrochemical *** cultures,starting from an initial culture density of 1×10^(8) cells/mL,were grown inside a sealed cellulose ester dialysis membrane,while polyethylene glycol in LB medium was used as the draw solution outside the membrane to gradually concentrate the growing cultures.0.7-mm-diameter graphite for mechanical pencils was utilized as working and counter electrodes with a platinum wire reference electrode for electrochemical measurements with and without the osmotic *** the absence of forward osmosis,impedance meas-urements detected culture growth~1 h faster than conventional *** osmosis showed a twofold decrease in the time to detect pyocyanin production as an indicator for bacterial *** impedance monitoring,removal of water by osmosis was conflated with the impedance decrease due to cell growth;however,the results show a promising ability to detect bacteria growth via an observed shift in osmotic impedance profile when bacteria are present in a *** monitoring the deviation in the impedance profile,a threefold improvement in detection time was achieved when compared to conventional Od600 measurements.

关键词： Osmotic concentration Pseudomonas aeruginosa Bacterial growth detection Impedance electrochemical monitoring Forward osmosis

Investigation of Terminal Group Effect on Electron Transport Through Open Molecular Structures

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Communications in Theoretical Physics 2013年第5期59卷 649-654页

作者： C. Preferencial Kala P. Aruna Priya d. john Thiruvadigal department of Physics and Nano Technology Center for Materials Science and NanodevicesSRM University department of Electronics and Communication Engineering Center for Materials Science and NanodevicesSRM University

The effect of terminal groups on the electron transport through metal-molecule-metal system has been investigated using nonequilibrium Green’s function (NEGF) formalism combined with extended Huckel theory (EHT). Au-molecule-Au junctions are constructed with borazine and BCN unit structure as core molecule and sulphur (S), oxygen (O), selenium (Se) and cyano-group (CN) as terminal groups. The electron transport characteristics of the borazine and BCN molecular systems are analyzed through the transmission spectra and the current-voltage curve. The results demonstrate that the terminal groups modifying the transport behaviors of these systems in a controlled way. Our result shows that, selenium is the best linker to couple borazine to Au electrode and oxygen is the best one to couple BCN to Au electrode. Furthermore, the results of borazine systems are compared with that of BCN molecular systems and are discussed. Simulation results show that the conductance through BCN molecular systems is four times larger than the borazine molecular systems. Negative differential resistance behavior is observed with borazine-CN system and the saturation feature appears in BCN systems.

关键词： molecular electronics extended Huckel theory (EHT) nonequilibrium Green’s function (NEGF) quantum transport

Explicit and Parameterized Episodes of Warm-Season Precipitation over the Continental United States

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Advances in Atmospheric Sciences 2006年第1期23卷 91-105页

作者： Mitchell W. MONCRIEFF john d. TUTTLE Richard E. CARBONE National Center for Atmospheric Research BoulderColorado 80307-3000U. S. A.

This paper describes explicit and parameterized simulations of midsummer precipitation over the continental United States for two distinct episodes： moderate large-scale forcing and weak forcing. The objective is to demonstrate the capability of explicit convection at currently affordable grid-resolution and compare it with parameterized realizations. Under moderate forcing, 3-kin grid-resolution explicit simulations represent rainfall coherence remarkably well. The observed daily convective generation near the Continental divide and the subsequent organization and propagation are reproduced qualitatively. The propagation speed, zonal extent and duration of the rainfall streaks compare favorably with their observed counterparts, although the streak frequency is underestimated. The simulations at -10-km grid-resolution applying conventional convective parameterization schemes also replicate reasonably well the diurnal convective regeneration in moderate forcing. The performance of the 3-km grid-resolution model demonstrates the potential of -1-km-resolution explicit cloud-resolving models for the prediction of warm season precipitation for moderately forced environments. In weak forcing conditions, however, predictions of precipitation coherence and diurnal variability are much poorer. This suggests that an even finer resolution explicit model is required to adequately treat convective initiation and upscale organization typical of the warm season over the continental U.S.

关键词： warm-season precipitation explicit simulation convective parameterization

Predictive modelling of ferroelectric tunnel junctions

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npj Computational Materials 2016年第1期2卷 150-162页

作者： Julian P Velev john d Burton Mikhail Ye Zhuravlev Evgeny Y Tsymbal department of Physics and Astronomy University of NebraskaLincolnNEUSA department of Physics and Astronomy University of Puerto RicoSan JuanPuerto RicoUSA Nebraska Center for Materials and Nanoscience University of NebraskaLincolnNEUSA Kurnakov Institute for General and Inorganic Chemistry Russian Academy of SciencesMoscowRussia Faculty of Liberal Arts and Sciences St Petersburg State UniversitySt PetersburgRussia

Ferroelectric tunnel junctions combine the phenomena of quantum-mechanical tunnelling and switchable spontaneous polarisation of a nanometre-thick ferroelectric film into novel device *** the ferroelectric barrier polarisation direction produces a sizable change in resistance of the junction—a phenomenon known as the tunnelling electroresistance *** a fundamental perspective,ferroelectric tunnel junctions and their version with ferromagnetic electrodes,i.e.,multiferroic tunnel junctions,are testbeds for studying the underlying mechanisms of tunnelling electroresistance as well as the interplay between electric and magnetic degrees of freedom and their effect on *** a practical perspective,ferroelectric tunnel junctions hold promise for disruptive device *** a very short time,they have traversed the path from basic model predictions to prototypes for novel non-volatile ferroelectric random access memories with non-destructive *** remarkable progress is to a large extent driven by a productive cycle of predictive modelling and innovative experimental *** this review article,we outline the development of the ferroelectric tunnel junction concept and the role of theoretical modelling in guiding experimental *** discuss a wide range of physical phenomena that control the functional properties of ferroelectric tunnel junctions and summarise the state-of-the-art achievements in the field.

关键词： ferroelectric tunnel resistance

History and evaluation of national-scale geochemical data sets for the United States

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Geoscience Frontiers 2013年第2期4卷 167-183页

作者： david B.Smith Steven M.Smith john d.Horton U.S.Geological Survey.denver Federal Center MS 973.DenverCO 80225USA

Six national-scale,or near national-scale,geochemical data sets for soils or stream sediments exist for the United *** earliest of these,here termed the ＇Shacklette＇ data set,was generated by a U.S. Geological Survey（USGS） project conducted from 1961 to *** project used soil collected from a depth of about 20 cm as the sampling medium at 1323 sites throughout the conterminous *** National Uranium Resource Evaluation Hydrogeochemical and Stream Sediment Reconnaissance（NUREHSSR） Program of the *** of Energy was conducted from 1975 to 1984 and collected either stream sediments,lake sediments,or soils at more than 378,000 sites in both the conterminous *** *** sampled area represented about 65%of the *** Natural Resources Conservation Service（NRCS）,from 1978 to 1982,collected samples from multiple soil horizons at sites within the major crop-growing regions of the conterminous *** data set contains analyses of more than 3000 *** National Geochemical Survey,a USGS project conducted from 1997 to 2009,used a subset of the NURE-HSSR archival samples as its starting point and then collected primarily stream sediments, with occasional soils,in the parts of the *** covered by the NURE-HSSR *** data set contains chemical analyses for more than 70,000 *** USGS,in collaboration with the Mexican Geological Survey and the Geological Survey of Canada,initiated soil sampling for the North American Soil Geochemical Landscapes Project in *** of three horizons or depths at more than 4800 sites in the *** completed in 2010,and chemical analyses are currently *** NRCS initiated a project in the 1990s to analyze the various soil horizons from selected pedons throughout the *** data set currently contains data from more than 1400 *** paper（1） discusses each data set in terms of its purpose,sample collection protocols,and analytical methods;and（2） evaluates each data set in terms

关键词： Geochemical mapping National-scale geochemical data Geochemical baselines United States

Fructose-sorbitol ingestion provokes gastrointestinal symptoms in patients with eating disorders

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World Journal of Gastroenterology 2009年第42期15卷 5295-5299页

作者： Noel Friesen Ross d Hansen Suzanne F Abraham john E Kellow department of Obstetrics and Gynaecology Royal North Shore HospitalUniversity of SydneySydney 2065Australia department of Gastroenterology Royal North Shore HospitalUniversity of SydneySydney 2065Australia

AIM:To evaluate gastrointestinal(GI) symptoms and breath hydrogen responses to oral fructose-sorbitol(F-S) and glucose challenges in eating disorder(Ed) ***:GI symptoms and hydrogen breath concentration were monitored in 26 female Ed inpatients for 3 h,following ingestion of 50 g glucose on one day,and 25 g fructose/5 g sorbitol on the next day,after an overnight fast on each *** to F-S were compared to those of 20 asymptomatic healthy ***:F-S provoked GI symptoms in 15 Ed patients and one healthy control(P d vs control) .Only one Ed patient displayed symptom provocation to glucose(P d in Ed patients with a body mass index(BMI) ≤ 17.5 kg/m 2 compared to those with a BMI > 17.5 kg/m 2(P differences in psychological scores,prevalence of functional GI disorders or breath hydrogen responses between patients with and without an F-S ***:F-S,but not glucose,provokes GI symptoms in Ed patients,predominantly those with low *** findings are important in the dietary management of Ed patients.

关键词： Fructose Sorbitol Malabsorption syndromes Functional gastrointestinal disorders Eating disorders Underweight