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Factors affecting trace element content in periurban market garden subsoil in Yunnan Province,China

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Journal of Environmental Sciences 2011年第3期23卷 488-496页

作者： Yanqun zu Laurent Bock christian Schvartz Gilles Colinet Yuan Li College of Resources and Environment Yunnan Agricultural University Kunming 650201 China Laboratory of Soil Science Gembloux Agro-bio Technology University Liege University Gembloux Belgium Laboratory of Soil and Environment Institute of Advanced Agriculture Catholic University Lille France

Field investigations were conducted to measure subsoil trace element content and factors influencing content in an intensive periurban market garden in Chenggong County, Yunnan Province, South-West China. The area was divided into three different geomorphological units： specifically, mountain （m）, transition （T） and lacustrine （L）. mean trace element content in subsoil were determined for Pb （58.2 mg/kg）, Cd （0.89 mg/kg）, Cu （129.2 mg/kg）, and Zn （97.0 mg/kg）. Strong significant relationships between trace element content in topsoil and subsoil were observed. Both Pb and Zn were accumulated in topsoil （RTS （ratio of mean trace element in topsoil to subsoil） of Pb and Zn ≥1.0） and Cd and Cu in subsoil （RTS of Cd and Cu≤1.0）. Subsoil trace element content was related to relief, stoniness, soil color, clay content, and cation exchange capacity. Except for 7.5 YR （yellow-red） color, trace element content increased with color intensity from brown to reddish brown. Significant positive relationships were observed between Fe content and that of Pb and Cu. Trace element content in mountain unit subsoil was higher than in transition and lacustrine units （m 〉 T 〉 L）, except for Cu （T 〉 m 〉 L）. mean trace element content in calcareous subsoil was higher than in sandstone and shale. mean trace element content in clay texture subsoil was higher than in sandy and sandy loam subsoil, and higher Cu and Zn content in subsoil with few mottles. It is possible to model Pb, Cd, Cu, and Zn distribution in subsoil physico-chemical characteristics to help improve agricultural practice.

关键词： trace elements subsoil topsoil relationships

Biologically Inspired Girder Structure for the Synchrotron Radiation Facility PETRA IV

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Journal of Bionic Engineering 2023年第5期20卷 1996-2017页

作者： Simone Andresen Norbert meyners Daniel Thoden markus Körfer christian Hamm Bionic Lightweight Design&Functional morphology Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research(AWI)Am Handelshafen 1227570BremerhavenGermany Deutsches Elektronen-Synchrotron(DESY) Notkestraße 8522607HamburgGermany

Lightweight structures are widely used across different industry ***,they get easily excited by external influences,such as *** high vibration amplitudes can be avoided by shifting the structural eigenfrequencies,which can be achieved adapting the structural design considering optimisation procedures and structures primarily inspired by *** procedures has been applied to the development process of a girder structure installed in a synchrotron radiation facility to support heavy magnets and other *** objective was to design a 2.9 m long girder structure with high eigenfrequencies,a high stiffness and a low *** on a topology optimisation result,a parametric beam–shell model including biologically inspired structures(e.g.,Voronoi combs,ribs,and soft and organic-looking transitions)was built *** subsequent cross-sectional optimisation using evolutionary strategic optimisation revealed an optimum girder structure,which was successfully manufactured using the casting *** measurements validated the numerical *** changes in the specifications can be implemented in the bio-inspired development process to obtain adapted girder structures.

关键词： Biomimetics Eigenfrequency maximisation Evolutionary structural optimisation Lightweight design Topology optimisation Voronoi combs

Schr?dinger and Klein-Gordon theories of black holes from the quantization of the Oppenheimer and Snyder gravitational collapse

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Communications in Theoretical Physics 2023年第9期 124-137页

作者： christian Corda Istituto Livi SUNY Polytechnic Institute International Institute for Applicable mathematics and Information Sciences B M Birla Science Centre

The Schr?dinger equation of the Schwarzschild black hole(BH) has been recently derived by the author and collaborators. The BH is composed of a particle, the ’electron’, interacting with a central field, the ’nucleus’. Via de Broglie’s hypothesis, one interprets the ’electron’ in terms of BH horizon’s modes. Quantum gravity effects modify the BH semi-classical structure at the Schwarzschild scale rather than at the Planck scale. The analogy between this BH Schr?dinger equation and the Schr?dinger equation of the s states of the hydrogen atom permits us to solve the same equation. The quantum gravitational quantities analogous of the fine structure constant and of the Rydberg constant are not constants, but the dynamical quantities have well-defined discrete spectra. The spectrum of the ’gravitational fine structure constant’ is the set of non-zero natural numbers. Therefore, BHs are well-defined quantum gravitational systems obeying Schr?dinger’s theory: the ’gravitational hydrogen atoms’. By identifying the potential energy in the BH Schr?dinger equation as being the gravitational energy of a spherically symmetric shell, a different nature of the quantum BH seems to surface. BHs are self-interacting, highly excited,spherically symmetric, massive quantum shells generated by matter condensing on the apparent horizon, concretely realizing the membrane paradigm. The quantum BH described as a’gravitational hydrogen atom’ is a fictitious mathematical representation of the real, quantum BH, a quantum massive shell having a radius equal to the oscillating gravitational *** consequences emerge from this result:(i) BHs have neither horizons nor singularities;(ii) there is neither information loss in BH evaporation, nor BH complementarity, nor firewall paradox. These results are consistent with previous ones by Hawking, Vaz, mitra and ***, the special relativistic corrections to the BH Schr?dinger equation give the BH Klein–Gordon equation and the cor

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Electronic structure modulation with ultrafine Fe_(3)O_(4) nanoparticles on 2D Ni-based metal-organic framework layers for enhanced oxygen evolution reaction

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Journal of Energy Chemistry 2022年第2期31卷 78-88页

作者： Wei Huang Chao Peng Jing Tang Fangyuan Diao murat Nulati Yesibolati Hongyu Sun christian Engelbrekt Jingdong Zhang Xinxin Xiao Kristian S.mølhave Department of Chemistry Technical University of DenmarkDK-2800 Kongens LyngbyDenmark DTU Nanolab-National Center for Nanofabrication and Characterization Technical University of DenmarkDK-2800 Kongens LyngbyDenmark multiscale Crystal materials Research Center Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055GuangdongChina

Two-dimensional(2D)metal organic frameworks(mOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation ***,ultrafine Fe_(3)O_(4) nanoparticles(diameter:6±2 nm)are homogeneously immobilized on 2D Ni based mOFs(Ni-BDC,thickness:5±1 nm)to improve the OER *** structure modulation for enhanced catalytic activity is studied via adjusting the amount of Fe_(3)O_(4) nanoparticles on *** optimal Fe_(3)O_(4)/Ni-BDC achieves the best OER performance with an overpotential of 295 mV at 10 mA cm^(-2),a Tafel slope of 47.8 mV dec^(-1) and a considerable catalytic durability of more than 40 h(less than 5 h for Ni-BDC alone).DFT calculations confirm that the active sites for Fe_(3)O_(4)/Ni-BDC are mainly contributed by Fe species with a higher oxidation state,and the potential-determining step(PDS)is the formation of the adsorbed O*species,which are facilitated in the composite.

关键词： Fe_(3)O_(4)nanoparticles 2D Ni-BDC Aggregation Electronic structure modulation Oxygen evolution reaction

Is Faster Necessarily Better? 3G Take-Up Rates and the Implications for Next Generation Services

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International Journal of Communications, Network and System Sciences 2012年第8期5卷 463-480页

作者： christian m. Dippon NERA Economic Consulting San Francisco USA

most countries have allocated 3G spectrum and are in the process of allocating advanced wireless services and 4G spectrum, both of which promise subscribers significantly faster broadband speeds. Operators anticipate that subscribers will adopt these services swiftly thereby justifying the large investments. Yet, why is it the case that only two countries in the world have more 3G than 2G subscribers? This study examines the drivers behind 3G diffusion using linear probability models and qualitative choice (logit) analysis. Time series diffusion models show that diffusion patterns follow an s-curve pattern, favoring the Gompertz curve.

关键词： Spectrum Diffusion Broadband Linear Probability models Qualitative Choice Analysis

Explaining the influence of dopant concentration and excitation power density on the luminescence and brightness of β-NaYF4:Yb^3+,Er^3+ nanoparticles:measurements and simulations

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Nano Research 2019年第8期12卷 1871-1879页

作者： martin Kaiser christian Wurth marco Kraft Tero Soukka Ute Resch-Genger Division Biophotonics Federal Institute for Materials Research and Testing (BAM)Richard-Willstaetter-Str. 11D-12489 BerlinGermany Department of Biotechnology University of TurkuKiinamyllynkatu 10TurkuFI-20520Finland

We assessed the influence of Yb^3+ and Er34 dopant concentration on the relative spectral distribution, quantum yield (Фuc), and decay kinetics of the upconversion luminescence (UCL) and particle brightness (BUC) for similarly sized (33 nm) oleate-capped p-NaYF4:Yb3t,Er^3+ upconversion (UC) nanoparticles (UCNPs) in toluene at broadly varied excitation power densities (F). This included an Yb^3+ series where the Yb^3+ concentration was varied between 11%—21% for a constant Er^3+ concentration of 3%, and an Er^3+ series, where the Er^3+ concentration was varied between 1%-4% for a constant Yb^3+ concentration of 14%. The results were fitted with a coupled rate equation model utilizing the UCL data and decay kinetics of the green and red Er34 emission and the Yb34 luminescence at 980 nm. An increasing Yb34 concentration favors a pronounced triphotonic population of 4F9/2 at high P by an enhanced back energy transfer (BET) from the 4G11/2 level. Simultaneously, the Yb^3+-controlled UCNPs absorption cross section overcompensates for the reduction in Фuc with increasing Yb^3+ concentration at high P, resulting in an increase in Sue. Additionally, our results show that an increase in Yb34 and a decrease in Er^3+ concentration enhance the color tuning range by P. These findings will pave the road to a deeper understanding of the energy transfer processes and their contribution to efficient UCL, as well as still debated trends in green-to-red intensity ratios of UCNPs at different P.

关键词： upconversion quantum yield color tuning nanoparticles dopant concentration rate equation model

modeling the middle Jurassic ocean circulation

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Journal of Palaeogeography 2015年第4期4卷 373-386页

作者： maura Brunetti christian Vérard Peter O.Baumgartner Institute for Environmental Sciences University of Geneva Institute of Earth Sciences University of Lausanne

We present coupled ocean-sea-ice simulations of the middle Jurassic（~165 ma） when Laurasia and Gondwana began drifting apart and gave rise to the formation of the Atlantic Ocean. Since the opening of the Proto-Caribbean is not well constrained by geological records, configurations with and without an open connection between the Proto-Caribbean and Panthalassa are examined. We use a sea-floor bathymetry obtained by a recently developed three-dimensional（3D） elevation model which compiles geological, palaeogeographical and geophysical data. Our original approach consists in coupling this elevation model, which is based on detailed reconstructions of oceanic realms, with a dynamical ocean circulation model. We find that the middle Jurassic bathymetry of the Central Atlantic and Proto-Caribbean seaway only allows for a weak current of the order of 2 Sv in the upper 1000 m even if the system is open to the West. The effect of closing the western boundary of the Proto-Caribbean is to increase transport related to barotropic gyres in the southern hemisphere and to change water properties, such as salinity, in the Neo-Tethys. Weak upwelling rates are found in the nascent Atlantic Ocean in the presence of this superficial current and we discuss their compatibility with deep-sea sedimentological records in this region.

关键词： Jurassic modeling ocean circulation palaeoclimate

Development and evaluation of an individual tree growth and yield model for the mixed species forest of the Adirondacks Region of New York, USA

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Forest Ecosystems 2017年第1期4卷 66-82页

作者： Aaron Weiskittel christian Kuehne John Paul mcTague mike Oppenheimer University of maine School of Forest Resources Orono ME 04469 USA. Rayonier Forest Research Center Yulee FL 32041 USA Rayonier Foresl Resources Fernandina Beach FL 32035 USA. University of maine 5755 I Nutting Hall Orono ME 04469-5755 USA.

Background： Growth and yield models are important tools for forest planning. Due to its geographic location, topology, and history of management, the forests of the Adirondacks Region of New York are unique and complex. However, only a relatively limited number of growth and yield models have been developed and/or can be reasonably extended to this region currently. methods： in this analysis, 571 long-term continuous forest inventory plots with a total of 10 - 52 years of measurement data from four experimental forests maintained by the State University of New York College of Environmental Science and Forestry and one nonindustrial private forest were used to develop an individual tree growth model for the primary hardwood and softwood species in the region. Species-specific annualized static and dynamic equations were developed using the available data and the system was evaluated for long-term behavior. Results： Equivalence tests indicated that the Northeast Variant of the Forest Vegetation Simulator （FVS-NE） was biased in its estimation of tree total and bole height, diameter and height increment, and mortality for most species examined. In contrast, the developed static and annualized dynamic, species-specific equations performed quite well given the underlying variability in the data. Long-term model projections were consistent with the data and suggest a relatively robust system for prediction. Conclusions： Overall, the developed growth model showed reasonable behavior and is a significant improvement over existing models for the region. The model also highlighted the complexities of forest dynamics in the region and should help improve forest planning efforts there.

关键词： Individual tree growth model mixed species Forest vegetation simulator

Growth and form of Quercus robur and Fraxinus excelsior respond distinctly different to initial growing space: results from 24-year-old Nelder experiments

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Journal of Forestry Research 2013年第1期24卷 1-14页

作者： christian Kuehne Patrick Pyttel Edgar Kublin Jürgen Bauhus Institute of Silviculture University of FreiburgD-79085 Freiburg i.Br.Germany. Faculty of Forests and Forestry University of Applied Sciences Wei- henstephan-TriesdorfHans-Carl-von-Carlowitz-Platz 3D-85354 FreisingGermany Department of Biometry and Informatics Forest Research Station Baden-WürttembergPostfach 708D-79007 FreiburgGermany

Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth （diameter at breast height, total height）, natural pruning （height to first dead and first live branch and branchiness） and stem and crown form of 24-year-old pedunculate oak （Quercus robur [L.]） and European ash （Fraxinus excelsior [L.]） were affected by initial spacing. Data were recorded from two replicate single-species Nelder wheels located in southern Germany with eight initial stocking regimes varying from 1,020 to 30,780 seedlings·ha？1. mortality substantially decreased with increasing initial growing space but significantly differed among the two species, averaging 59% and 15% for oak and ash plots, respectively. In contrast to oak, the low self-thinning rate found in the ash plots over the investigated study period resulted in a high number of smaller intermediate or suppressed trees, eventually retarding individual tree as well as overall stand development. As a result, oak gained greater stem dimensions throughout all initial spacing regimes and the average height of ash significantly increased with initial growing space. The survival of lower crown class ashes also appeared to accelerate self-pruning dynamics. In comparison to oak, we observed less dead and live primary branches as well as a smaller number of epicormic shoots along the first 6 m of the lower stem of dominant and co-dominant ashes in all spacing regimes. Whereas stem form of both species was hardly affected by initial growing space, the percentage of brushy crowns significantly increased with initial spacing in oak and ash. Our findings suggest that initial stockings of ca. 12,000 seedlings per hectare in oak and 2,500 seedlings per hectare in ash will guarantee a sufficient number of at least 300 potential crop trees per hectare in pure oak and ash plantations at the end of the self-thinning phase, respectively. If the problem of epicormic shoots a

关键词： spacing trial stocking self-thinning intraspecific competition qualification spatially explicit modelling generalized additive model