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Seasonal variability in CDOM absorption and fluorescence properties in the Barataria Basin,Louisiana,Usa

Journal of Environmental Sciences 2010年第10期22卷 1481-1490页

作者： Shatrughan Singh Eurico D'sa Erick Swenson Department of Oceanography and Coastal Sciences Louisiana State University

Absorption and fluorescence properties of chromophoric dissolved organic matter （CDOM） along a 124 km transect in the Barataria Basin, a large estuary located in Louisiana, Usa, were investigated during high and low flow periods of the Mississippi River in the spring and winter of 2008-2009. Mean CDOM absorption at 355 nm from the marine to the freshwater end member stations ranged from （3.25 ± 0.56） to （20.76 ± 2.43） m^-1 for the three month high flow period whereas it varied from （1.48 ± 1.08） to （25.45 ± 7.03） m^-1 for the same stations during low flow period. Corresponding salinity values at these stations indicated the influence of river and shelf exchanges in the lower basin and precipitation and runoff in the upper basin. An inverse relationship of CDOM absorbance and fluorescence with salinity observed in the basin could he a useful indicator of salinity. CDOM fluorescence also varied over a large range showing an approximately 8 to 12-fold increase between the marine and freshwater end members for the two flow seasons. Excitation-emission matrix spectral plots indicated the presence of various fluorescence components with highest being the A-peak, lowest the T-peak, and the C and M-peaks showing similar trends along the transect. During low flow season the A/C ratio were well correlated with station locations indicating increased terrestrial influence towards the upper basin. CDOM absorption and fluorescence at 355 nm were highly correlated and independent of CDOM sources suggesting that fluorescence could be used to characterize CDOM in the basin.

关键词： Barataria Basin chromophoric dissolved organic matter CDOM fluorescence excitation-emission matrix

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Bioinspired nanotransducers for neuromodulation

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Nano Research 2024年第2期17卷 618-632页

作者： Fan Yang Xiang Wu sa Cai Guosong Hong Department of Materials Science and Engineering Stanford UniversityStanfordCA 94305USA Wu Tsai Neurosciences Institute Stanford UniversityStanfordCA 94305USA School of Science Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China

The field of neuromodulation has experienced significant advancements in the past decade,owing to breakthroughs in disciplines such as materials science,genetics,bioengineering,photonics,and *** convergence of these fields has resulted in the development of nanotransducers,devices that harness the synergies of these diverse *** nanotransducers,essential for neuromodulation,often draw inspiration from energy conversion processes found in nature for their unique *** this review,we will delve into the latest advancements in wireless neuromodulation facilitated by optical,magnetic,and mechanical *** will examine their working principles,properties,advantages,and limitations in comparison to current methods for deep brain neuromodulation,highlighting the impact of natural systems on their design and ***,we will underscore potential future directions,emphasizing how continued progress in materials science,neuroscience,and bioengineering might expand the horizons of what is achievable with nanotransducer-enabled neuromodulation.

关键词： bioinspired synthesis neuromodulation mechanoluminescence focused ultrasound nanotransducers sono-optogenetics

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Effect of additives on iron recovery and dephosphorization by reduction roasting-magnetic separation of refractory high-phosphorus iron ore

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International Journal of Minerals,Metallurgy and Materials 2021年第12期28卷 1908-1916页

作者： Shi-chao Wu Zheng-yao Li ti-chang Sun Jue Kou Xiao-hui Li School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China

The effect of CaCO_(3),Na_(2)CO_(3),and CaF_(2) on the reduction roasting and magnetic separation of high-phosphorus iron ore containing phosphorus in the form of Fe_(3)PO_(7) and apatite was *** results revealed that Na_(2)CO_(3) had the most significant effect on iron recovery and dephosphorization,followed by CaCO_(3),the effect of CaF_(2) was *** mechanisms of CaCO_(3),Na_(2)CO_(3),and CaF_(2) were investigated using X-ray diffraction(XRD),scanning electron microscopy and energy dispersive spectrometry(SEM-EDS).Without additives,Fe_(3)PO_(7) was reduced to elemental phosphorus and formed an iron-phosphorus alloy with metallic *** addition of CaCO_(3) reacted with Fe_(3)PO_(7) to generate an enormous amount of Ca_(3)(PO_(4))_(2) and promoted the reduction of iron ***,the growth of iron particles was *** the addition of Na_(2)CO_(3),the phosphorus in Fe_(3)PO_(7) migrated to nepheline and Na_(2)CO_(3) improved the reduction of iron oxides and growth of iron ***,the recovery of iron and the separation of iron and phosphorus were the *** contrast,CaF_(2) reacted with Fe_(3)PO_(7) to form fine Ca_(3)(PO_(4))2 particles scattered around the iron particles,making the separation of iron and phosphorus difficult.

关键词： alloy phosphorus separation

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Effect of Sodium Sulfate on Direct Reduction of Beach titanomagnetite for Separation of Iron and titanium

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Journal of Iron and Steel Research International 2016年第5期23卷 428-433页

作者： En-xia GAO ti-chang SUN Zhi-guo LIU Chao GENG Cheng-yan XU School of Civil and Environmental Engineering University of Science and Technology Beijing

The effect of sodium sulfate on direct reduction of beach titanomagnetite,followed by magnetic separation,to separate iron and titanium was investigated. Direct reduced iron（ DRI） with a high Fe content,low tiO_2 content and low iron recovery was obtained after adding sodium sulfate. When the sodium sulfate dosage was increased from 0 to 10 mass%,the Fe content of the DRI increased from 90. 00 mass% to 93. 55 mass% and the tiO_2 content decreased from 1. 27 mass% to 0. 70 mass%. The reduction mechanism of sodium sulfate was investigated by X-ray diffraction（ XRD） and scanning electron microscopy（ SEM） with energy dispersive spectrometer（ EDS）. Results revealed that the metallic iron grains in the reduced ore with sodium sulfate were larger than those in the ore without sodium sulfate. Sodium sulfate promoted the migration of iron as well as the accumulation and growth of metallic iron grains by low-melting-point carnegieite and troilite formed in the redox system. Low-melting-point carnegieite decreased the melting point of the system and then promoted liquefaction. Troilite could decrease the surface tension and melting point of metallic iron grains.

关键词： beach titanomagnetite sodium sulfate direct reduction separation iron titanium

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Electronic properties and photodegradation ability of Nd-tiO_(2)for phenol

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Journal of Rare Earths 2022年第7期40卷 1063-1072页

作者： Zhimin Zhao Jinjia Liu Gala sa Aiju Xu Inner Mongolia Key Laboratory of Green Catalysis College of Chemistry and Environmental ScienceInner Mongolia Normal UniversityHohhot 010022China State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of SciencesTaiyuan 030001China National Energy Center for Coal to Clean Fuels Synfuels China Co.Ltd.Beijing 101400China

In this study,the photocatalytic activity of Nd-tiO_(2)photocatalysts obtained by common hydrothermal method was evaluated by practical experiments and theoretical calculations based on density functional theory(DFT).The synthesized photocatalysts were characterized by X-ray diffraction(XRD),N_(2)adsorption-desorption,Fourier transform infrared spectroscopy(FT-IR),high resolution transmission electron microscopy(HRTEM),X-ray photoelectron spectroscopy(XPS),UV-Vis diffuse reflectance spectroscopy(DRS),and photoluminescence(PL)to study their physical/chemical prope *** the same time,the photoelectronic performance was also *** photodegradation ability of asprepared photocatalysts and the effect of Nd doped amount and photocatalysts dosage were investigated by the photodegradation of phenol(30 mg/L)under 400 W metal halide lamp(UV-Vis).The effect of Nd on electronic properties of tiO_(2)and adsorption ability of phenol were *** show the red-shift wavelength of 0.5 mol%Nd-tiO_(2),indicating that its absorption capacity is stronger than pristine tiO_(2)in the same wavelength *** result of DFT calculations demonstrates that the optical bandgap of Nd-tiO_(2)is profoundly reduced,thus the light absorption ability is promoted,which will be responsible for the enhanced photocatalytic performance of Nd-tiO_(2).0.5 mol%Nd is an optimum value for photodegradation phenol,and phenol can be completely degraded by 0.5 mol%Nd-tiO_(2)for 210 min,the higher catalytic performance is derived from the efficient separation of e-/h+***,the adsorption energy calculations of phenol on tiO_(2)(101)and Nd-tiO_(2)(101)demonstrate that the Nd doping can significantly enhance the adsorption ability of phenol on catalyst surfaces because of the formation of Nd-O *** last,the stability measurement through four recycles exhibits that 0.5 mol%Nd-tiO_(2)possesses excellent stability.

关键词： tiO_(2) Hydrothermal method Density functional theory Phenol Photodegradation Rare earths

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Formation of calcium titanate in the carbothermic reduction of vanadium titanomagnetite concentrate by adding CaCO3

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International Journal of Minerals,Metallurgy and Materials 2020年第6期27卷 745-753页

作者： Xiao-hui Li Jue Kou ti-chang Sun Shi-chao Wu Yong-qiang Zhao School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China

The formation of calcium titanate in the carbothermic reduction of vanadium titanomagnetite concentrate(VTC)by adding CaCO3 was *** analysis was employed to show the feasibility of calcium titanate formation by the reaction of ilmenite and Ca CO3 in a reductive atmosphere,where ilmenite is more easily reduced by CO or carbon in the presence of *** effects of CaCO3 dosage and reduction temperature on the phase transformation and metallization degree were also investigated in an actual roasting *** increase of CaCO3 dosages and reduction temperatures were found to be conducive to the formation of calcium titanate,and the optimum conditions were a CaCO3 dosage of 18 wt%and a reduction temperature of 1400°***,scanning electron microscopy–energy dispersive spectrometry(SEM–EDS)analysis shows that calcium titanate produced via the carbothermic reduction of VTC by CaCO3 addition was of higher purity with particle size approximately 50μ***,the separation of calcium titanate and metallic iron will be the focus in the future study.

关键词： vanadium titanomagnetite concentrate calcium carbonate carbothermic reduction metallic iron calcium titanate

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Developing Weibull-based diameter distributions for the major coniferous species in Heilongjiang Province,China

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Journal of Forestry Research 2023年第6期34卷 1803-1815页

作者： Qila sa Xingji Jin timo Pukkala Fengri Li Key Laboratory of Sustainable Forest Ecosystem Management Ministry of EducationNortheast Forestry UniversityHarbin 150040People’s Republic of China University of Eastern Finland 80101 JoensuuFinland

Diameter distribution models play an important role in forest inventories,growth prediction,and *** Weibull probability density function is widely used in *** a number of methods have been proposed to predict or recover the Weibull distribution,their applicability and predictive performance for the major tree species of China remain to be *** in sample plots of three even-aged coniferous species(Larix olgensis,Pinus sylvestris and Pinus koraiensis)were measured both in un-thinned and thinned stands to develop parameter prediction models for the Weibull probability density *** least squares(OLS)and maximum likelihood regression(MLER),as well as cumulative distribution function regression(CDFR)were used,and their performance *** results show that MLER and CDFR were better than OLS in predicting diameter distributions of tree *** produced the best results in terms of fitting *** on the error statistics calculated for different age groups,CDFR was considered the most suitable method for developing prediction models for Weibull parameters in coniferous plantations.

关键词： Parameter prediction Maximum likelihood regression Cumulative distribution function regression

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Flow variability along a vegetated natural stream under various sediment transport rates

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Journal of Mountain Science 2018年第11期15卷 2347-2364页

作者： WANG Hai-zhou Xu Ze-xing Yu Hai-ti WANG Xie-kang State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University

The influence of vegetation and sediment on flow characteristics in open channels cannot be neglected. To study the flow variability under the effects of the instream natural vegetation and sediment supply, experiments were conducted with varied water and sediment supply in a movable bed of a river prototype. The instantaneous threedimensional velocities near two types of vegetation patches(the shrub and the weed) and along the centerline of the main channel with vegetation belts were measured using a 3-D side-looking acoustic Doppler velocimetry. The experimental results show that both the instream vegetation and sediment supply strongly affect the flow and turbulence characteristics. In the case of vegetation patches, both the shrub and weed have a considerable influence on the distribution of the streamwise velocity and turbulence intensity of their surrounding water. The streamwise velocity distribution followed as J-shape and linear shape around the weed and shrub under different experimental conditions. The turbulence intensity was large at the top of the weed and shrub;the shrub had its greatest influence on the downstream water flow. In the case of vegetation belts,the streamwise velocity along the centerline of the main channel exhibited an S-shape, J-shape and linear shape at different locations under varied water,vegetation structures and riverbed *** turbulence intensity along the centerline of the main channel ranged from 0.0 to 0.1. The upstream turbulence intensity was affected considerably by a sediment supply, while the downstream turbulence intensity changed with the varied vegetation characteristics and riverbed topography. The second flow coefficient M-value increased longitudinally and was almost positive along the centerline of the main channel, implying that the rotational direction of the secondary current cell was clockwise.

关键词： Natural vegetation Sediment supply Velocity profile Turbulence intensity Secondary flow Movable bed

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Introduction of Constrained Cyclic Skeleton into β-Enaminoketonato Vanadium Complexes： A Strategy for Stabilization of Active Centre of Vanadium Catalyst for Ethylene Polymerization

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Chinese Journal of Polymer Science 2017年第9期35卷 1110-1121页

作者： Kai-ti Wang Yong-xia Wang Bin Wang Yan-guo Li 李悦生 Changchun Institute of Applied Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences tianjin Key Lab of Composite & Functional Materials School of Materials Science and EngineeringTianjin University

Several novel mono（β-enaminoketonato） vanadium complexes bearing constrained [（C6Hs）C6H3C（O）=C（CH2）nCH=N-Ar]VCl2（THF）2 （V3a： n = 1, Ar = C6H5; V4a： n = 2, Ar cyclic skeleton, including C6H5; V4b： n = 2, Ar C6F5; V4c： n = 2, Ar = （C3H7）2C6H3; V5a： n = 3, Ar = C6H5）, were synthesized and their structure and properties were characterized. The structures of V4c and V5a in solid-state were further confirmed by X-ray crystallographic analysis. Density functional theory （DFT） results indicated that these complexes showed enhanced steric hindrance around the metal center as compared with the acyclic analogues. Upon activation with Et2AlCl and in the presence of ethyl trichloroacetate as a reactivator, all of the complexes exhibited high catalytic activities （107 gPE/（molv.h）） toward ethylene polymerization, and the obtained polymers exhibited unimodal distributions （Mw/Mn = 2.0-2.3） even produced at elevated temperatures （70-100 ℃） and prolonged reaction time. When MAO was employed as a cocatalyst, they only showed moderate catalytic activities （10^5 gPE/（molv·h））, but the resulting polymers had higher molecular weights （168-241 kg/mol）. These vanadium complexes with cyclic skeleton also showed high catalytic activities toward ethylene/norbornene copolymerization. The produced copolymers displayed approximate alternating structure at high in-feed concentration of norbornene. The catalytic capabilities of these complexes could be tuned conveniently by varying ligand structure. Furthermore, the cyclic voltammetry results also proved that these complexes exhibited better redox stabilities than the complexes bearing linear skeleton.

关键词： Vanadium catalysts Ethylene polymerization Cyclic skeleton Steric protection

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Microstructure and properties of pure iron/copper composite cladding layers on carbon steel

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International Journal of Minerals,Metallurgy and Materials 2016年第8期23卷 920-927页

作者： Long Wan Yong-xian Huang Shi-xiong Lü ti-fang Huang Zong-liang Lü State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Harbin World Wide Welding Co. Ltd.

In the present study, pure iron/copper composite metal cladding was deposited onto carbon steel by tungsten inert gas welding. The study focused on interfacial morphological, microstructural, and mechanical analyses of the composite cladding layers. Iron liquid–solid-phase zones were formed at copper/steel and iron interfaces because of the melting of the steel substrate and iron. Iron concentrated in the copper cladding layer was observed to exhibit belt, globule, and dendrite morphologies. The appearance of iron-rich globules indicated the occurrence of liquid phase separation（LPS） prior to solidification, and iron-rich dendrites crystallized without the occurrence of LPS. The maximum microhardness of the iron/steel interface was lower than that of the copper/steel interface because of the diffusion of elemental carbon. All samples fractured in the cladding layers. Because of a relatively lower strength of the copper layer, a short plateau region appeared when shear movement was from copper to iron.

关键词： tungsten inert gas welding metal cladding pure iron copper carbon steel interfacial properties

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