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Seasonal dependency of controlling factors on the phytoplankton production in Taihu lake, China

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Journal of Environmental Sciences 2019年第2期31卷 278-288页

作者： Qiaohua Zhao Jing Wang Jianjian Wang Julian x.l.Wang College of Hydrometeorology Nanjing University of Information Science and Technology Air Resources laboratory National Oceanic and Atmospheric AdministrationCollege Park

In this study, 44 profiles of gross primary productivity(GPP) and sunlight, along with water temperature, Chlorophyll-a(Chla) and nutrients, were observed in Meiliang Bay of Taihu lake, China, in the spring, summer, and fall seasons. Effects of water temperature, light,and nutrient concentration were examined in relation to the GPP-unit-Chla(GPP of algae per Chla). The results showed that the optimum temperature for the GPP of phytoplankton was 27.9°C, the optimal PNA-unit-Chla(photon number absorbed by phytoplankton per Chla) was 0.25(mol), and the HSCN-unit-Chla and HSCP-unit-Chla(half-saturation constants of nitrogen and phosphorus of algae per Chla) were 0.005(mg/l) and 0.0004(mg/l), respectively. The seasonal dependency of the effect of different factors on the GPP was analyzed. Compared with temperature and nutrients, light was found to be the most important factor affecting the GPP during the three seasons. The effect of temperature and nutrients on the GPP of phytoplankton has obvious seasonal change. In spring, temperature was the secondary factor affecting the GPP of phytoplankton, and the effect of nutrients may be negligible in the eutrophic lake on account of temperature limit, which showed that the GPP of algae was only affected by the physical process. In summer and fall, temperature didn't affect the GPP of algae, and the presence of nutrients was the secondary factor affecting the GPP of phytoplankton. From summer to fall, effect of phosphorus was weakened and effect of nitrogen was enhanced.

关键词： Temperature limited effect Gross primary productivity Eutrophication light limit optimum temperature Half-saturation constants

Mechanism of wavy vortex and sign laws in flow past a bluff body:vortex-induced vortex

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Acta Mechanica Sinica 2019年第1期35卷 1-14,I0001页

作者： l.M.lin S.Y.Shi x.F.Zhong Y.x.Wu Key laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

As reported in a previous work by lin et al.(Acta Meeh Sin, 2018. https://***/10.1007/s 10409-018-0758-z), an interesting phenomenon was discovered based on the analysis of wavy vortex and vorticity distribution in the shear layers and near wake of a peak-perforated conic shroud, and two sign laws were summarized. In the present paper, the theory of a vortex-induced vortex is introduced to explore mechanisms in a wavy vortex and applicable sign laws for uniform and incompressible flow past a fixed bluff body. Based on the analysis of the nearest-wall How, two vortex-induced models for streamwise and vertical vortex pairs, respectively, are proposed under two boundary cases, denoting the induced vorticity introduced or distributed on and near the walls. As a result, the first sign law, for only streamwise and vertical components of vorticity, and the second sign law, for three components of vorticity, are obtained under their own particular conditions. The first sign law reveals the intrinsic physical relationship between streamwise and vertical vorticities, independent of the distribution of spanwise vortices in the whole flow field. It is also confirmed that the spanwise vortices, as well as the shear layers and wake width, distributed wavily across the span, are attributed to the introduced streamwise or vertical vortices. The two sign laws for vorticity are independent of the disturbed spanwise wavelength and the Reynolds number. Through the analysis of flow past the conic shroud, the two sign laws are successfully used to summarize typical spacial distributions of vorticity in three flow regions: on and near the front cylinder surfaces, the separated shear layers and the near wake.

关键词： Wavy vortex Sign law Vortex-induced vortex Wake Bluff body

Accelerating bainite transformation by concurrent pearlite formation in a medium Mn steel:Experiments and modelling

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Journal of Materials Science & Technology 2024年第9期176卷 211-223页

作者： l.K.Huang F.liu M.x.Huang Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina State Key laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’anShaanxi710072China

Bainite transformation has yet to be utilized and even thoroughly studied in medium Mn ***,we investigate the isothermal bainite transformation in a 10Mn steel at 450°C experimentally and theoretically,focusing on the effect of dislocations introduced by warm *** show that the bainite transformation in the studied medium Mn steel exhibits extremely sluggish kinetics(on a time scale of days),concurrent with the pearlite *** introduced dislocations can significantly accelerate bainite transformation kinetics while also facilitating the pearlite *** is likely the first report on the simultaneous occurrence of these two solid-state reactions in medium Mn *** respect to the roles of dislocations in the acceleration of bainite transformation observed in this work,we propose a new‘carbon depletion mechanism’,in which dislocations-stimulated pearlite formation makes a twofold contribution:facilitating the formation of bainitic ferrite sub-units to further enhance the autocatalytic effect and preventing the carbon enrichment in the remaining *** this basis,a physical model is developed to quantitatively understand the bainite transformation kinetics considering the effect of concurrent pearlite formation,revealing good agreements between model descriptions and experiment *** findings,herein,offer fundamental insights into the bainite transformation in medium Mn steels and uncover a previously unidentified role played by introduced dislocations in influencing the kinetics of bainite formation,which may guide its future application in manipulating microstructure for the development of advanced high-strength steels.

关键词： Medium Mn steels Bainite Thermodynamics Kinetics Phase transformation

Fate and transport of theβ-adrenergic agonist ractopamine hydrochloride in soil–water systems

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Journal of Environmental Sciences 2016年第7期28卷 40-48页

作者： Heldur Hakk Weilin l.Shelver Francis x.M.Casey USDA-ARS Biosciences Research laboratory 1605 Albrecht Blvd.FargoND 58102USA Department of Soil Sciences North Dakota State UniversityAlbrecht Blvd.FargoND 58108USA

The feed additive ractopamine hydrochloride was fortified at four concentrations into batch vials containing soils that differed in both biological activity and organic matter（oM）.Sampling of the liquid layer for 14 days demonstrated that ractopamine rapidly dissipated from the liquid layer. less than 20% of the fortified dose remained in the liquid layer after 4 hr,and recoveries of dosed ractopamine ranged from 8 to 18% in the liquid layer at 336 hr. Sorption to soil was the major fate for ractopamine in soil：water systems, i.e., 42%–51% of the dose at14 days. The major portion of the sorbed fraction was comprised of non-extractables; a smaller fraction of the sorbed dose was extracted into water and acetone, portions which would be potentially mobile in the environment. Partitioning coefficients for all soils suggested strong sorption of ractopamine to soil which is governed by hydrophobic interactions and cation exchange complexes within the soil oM. Ractopamine degradation was observed, but to mostly non-polar compounds which had a higher potential than ractopamine to sorb to soil. The formation of volatiles was also suggested. Therefore, despite rapid and extensive soil sorption,these studies indicated a portion of ractopamine, present in manures used to fertilize soils,may be mobile in the environment via water-borne events.

关键词： Ractopamine Transport Degradation β-Adrenergic agonist Soil

Evaluation of carbon-based nanosorbents synthesised by ethylene decomposition on stainless steel substrates as potential sequestrating materials for nickel ions in aqueous solution

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Journal of Environmental Sciences 2012年第9期24卷 1559-1568页

作者： x.J.lee l.Y.lee l.P.Y.Foo D.G.Hassell Department of Chemical and Environmental Engineering University of Nottingham Malaysia CampusJalan Broga43500 SemenyihSelangor Darul EhsanMalaysia.

The present work covers the preparation of carbon-based nanosorbents by ethylene decomposition on stainless steel mesh without the use of external catalyst for the treatment of water containing nickel ions （Ni2＋）. The reaction temperature was varied from 650 to 850℃, while reaction time and ethylene to nitrogen flow ratio were maintained at 30 rain and 1：1 cma/min, respectively. Results show that nanosorbents synthesised at a reaction temperature of 650℃ had the smallest average diameter （75 nm）, largest BET surface area （68.95 m2/g） and least amount of impurity （0.98 wt.% Fe）. A series of batch sorption tests were performed to evaluate the effects of initial pH, initial metal concentration and contact time on Ni2~ removal by the nanosorbents. The equilibrium data fitted well to Freundlich isotherm. The kinetic data were best correlated to a pseudo second-order model indicating that the process was of chemisorption type. Further analysis by the Boyd kinetic model revealed that boundary layer diffusion was the controlling step. This primary study suggests that the prepared material with Freundiich constants compared well with those in the literature, is a promising sorbent for the sequestration of Ni2＋ in aqueous solutions.

关键词： adsorption nanosorbent nickel ions isotherms kinetics

Hybrid Tio_(2)/Ag NPs/g-C_(3)N_(4) nanocomposite coatings on TC4 titanium alloy for enhanced synergistic antibacterial effect under full spectrum light

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Journal of Materials Science & Technology 2022年第23期118卷 35-43页

作者： xi.Rao l.Du J.J.Zhao x.D.Tan Y.x.Fang l.Q.xu Y.P.Zhang School of Materials and Energy Southwest UniversityChongqing 400715China Chongqing Key laboratory of Soft-Matter Material Chemistry and Function Manufacturing Southwest UniversityChongqing 400715China

The hybrid Tio_(2)/AgNPs/g-C_(3) N_(4) nanocomposite coatings were constructed on TC4 alloy by a hydrothermal and calcining ***_(2)/AgNPs/g-C_(3) N_(4) nanocomposite coatings demonstrated excellent biocompatibility and osteogenesis compared to those of titanium *** existence of trace AgNPs on the surface and interface of the heterojunction could further enhance the transfer and separation of photogenerated electron/hole pairs,which greatly improved the antibacterial performance under full spectrum *** at the valence band of Tio_(2) and g-C_(3) N_(4) reacted with adsorbed H_(2) o to generate·oH,killing bacteria through photocatalytic redox reaction under light irradiation,while released AgNPs exhibited bacteriostatic efficacy with or without *** study provides a pathway of coating modification for further improving the antibacterial properties of heterojunction coatings and maintaining the biocompatibility of matrix materials.

关键词： Tio_(2)/AgNPs/g-C_(3)N_(4)nanocomposite g-C_(3)N_(4) Photocatalysis Photocatalytic inactivation of bacteria Disinfection mechanism

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Science China(Physics,Mechanics & Astronomy) 2014年第3期57卷 418-423页

作者： l Yan BAo JingDong School of Applied Science Taiyuan University of Science and Technology Department of Physics Beijing Normal University

The correlated levy flight is studied analytically in terms of the fractional Fokker-Planck equation and simulated numerically by using the langevin equation, where the usual white ltvy noise is generalized to an ornstein-Uhlenbeck levy process （oAlP） with a correlation time τc. We analyze firstly the stable behavior of oUlP. The probability density function of ltvy flight particle driven by the oUlP in a harmonic potential is exactly obtained, which is also a ltvy-type one with Tc-dependence width; when the particle is bounded by a quartic potential, its stationary distribution has a bimodality shape and becomes noticeable with the increase of τc.

关键词： l3vy flight oUlP fractional Fokker-Planck equation

Cracking Susceptibility After Post-Weld Heat Treatment in Haynes 282 Nickel Based Superalloy

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Acta Metallurgica Sinica(English letters) 2013年第6期26卷 747-753页

作者： l.o.osoba A.K.Khan S.o.Adeosun Department of Metallurgical and Materials Engineering University of Lagos Department of Mechanical and Manufacturing Engineering University of Manitoba

This paper presents a study of the standard post-weld heat treatment （PWHT） behaviour of autogenous laser welded γ＇ age-hardenable precipitation strengthened nickel based superalloy Haynes 282 （HY 282）. The study involves a careful and detailed microstructural characterisation as well as an analysis of the weld cracking susceptibility during welding and Gleeble thermo-mechanical physical simulation. Various factors that could influence post-weld cracking in superalloys weld were experimentally examined. our microstructural exami- nation of the as-solution heat treated （SHTed） material and the thermo-mechanically refined grain material shows that intergranular heat affected zone （HAZ） cracking is observable in only the as-welded SHTed material. There was no indication of post-weld heat treatment cracking in all welded materials. our conclusion, in this study, is that the chemistry of superalloy HY 282 which aids the preclusion/formation of deleterious so- lidification microconstituents during welding as well as its relatively slow aging kinetics enhances its resistance to PWHT cracking.

关键词： Cracking Microstructure Analysis Nickel based Superalloy

CAlCUlATIoN oF SECoND PHASE PARTIClE-GRAIN BoUNDARY INTERACTIoN RANGE

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Acta Metallurgica Sinica(English letters) 2008年第1期21卷 8-14页

作者： x.l. Wang Y.H. Wei W. Wang l.F. Hou College of Materials Science and Engineering Taiyuan University of Technology Taiyuan 030024 China Baosteel Technology Center Baoshan Iron ＆ Steel Co. Ltd. Shanghai 201900 China Manuscript received 20 December 2006

on the basis of the grain boundary equation by HeUman and corresponding analysis of Worner, this article deals with the interaction range between the second-phase particle （SPP） and grain boundary （GB） as viewed from the applicability of grain boundary equation. Also, a new expression describing the interaction range has been derived, which solves the problem in theory that the interaction range between SPP and GB can only be qualitatively analyzed previously. It is shown that given the interaction position between SPP and GB, the interaction range can be quantitatively determined by use of this expression.

关键词： Second-phase particle Grain boundary Pinning force Surface free energy