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Hong H.-S.,Xiamen University | Wang Y.-J.,Chinese Academy of Sciences | Wang Y.-J.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Wang Y.-J.,CAS Yantai Institute of Coastal Zone Research | Wang D.-Z.,Xiamen University
Continental Shelf Research | Year: 2011

This study investigated the activities of two nitrogen assimilation enzymes, nitrate reductase (NR) and glutamine synthetase (GS) in phytoplankton in relation to sample, as well as the nutrient levels and phytoplankton biomass (Chl- a concentrations) during an upwelling event in the southern Taiwan Strait during an upwelling period from 6 to 12 July, 2005. The results showed that high NR activity (NRA) was always found with low nitrate and high Chl-a concentrations, while GS activity (GSA) exhibited positive correlations with ammonium and Chl-a concentration. Both NRA and GSA varied with the time and stage of upwelling: high NRA and GSA were observed initially at the subsurface layers in the early stage of upwelling, accompanied by the consumption of nutrients and the increase of Chl-a concentration; and then at the surface with high Chl-a concentrations in the middle and late stages of upwelling. Results from in situ enzyme bioassays on water samples along the tracing of upwelling track and on board mesocosm experiments on board the ship showed that there was a time-lag between nitrate addition and NRA and GSA, but. However, no time-lag was found between ammonium addition and GSA. The present results indicated that both NRA and GSA reflect the status of ambient nitrogen levels and the assimilation process of the phytoplankton, and could be used as effective parameters for the analysis of the physiological response of the phytoplankton to nitrogen variations during upwelling periods. Measurements of NRA and GSA in the phytoplankton in newly upwelled water appeared to provide ecophysiological indicators of phytoplankton, which will make it possible to trace during the sequence of upwelling events (such as nutrient supplementation) leading to enhanced productivity. © 2011 Elsevier Ltd. Source

Wang Y.,CAS Yantai Institute of Coastal Zone Research | Wang Y.,Chinese Academy of Sciences | Chen L.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes
Nanomedicine: Nanotechnology, Biology, and Medicine | Year: 2011

Quantum dots (QDs) have proven themselves as powerful inorganic fluorescent probes, especially for long term, multiplexed imaging and detection. The newly developed QDs labeling techniques have facilitated the study of drug delivery on the level of living cells and small animals. Moreover, based on QDs and fluorescence imaging system, multifunctional nanocomplex integrated targeting, imaging and therapeutic functionalities have become effective materials for synchronous cancer diagnosis and treatment. In this review, we will summarize the recent advances of QDs in the research of drug delivery system from the following aspects: surface modification strategies of QDs for drug delivery, QDs as drug nanocarriers, QD-labeled drug nanocarriers, QD-based fluorescence resonance energy transfer (FRET) technique for drug release study as well as the development of multifunctional nanomedicines. Possible perspective in this field will also be discussed. © 2010 Elsevier Inc. Source

Zhang G.,National University of Singapore | Zhang G.,CAS Yantai Institute of Coastal Zone Research | Zhang G.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Khorshed A.,National University of Singapore | Paul Chen J.,National University of Singapore
Journal of Colloid and Interface Science | Year: 2013

Arsenate and arsenite typically co-exist in groundwater. Arsenite is more toxic than arsenate, while it is more difficult to be removed than arsenate. In order to effectively remove arsenate and arsenite simultaneously from water solution, a nanostructured zirconium-manganese binary hydrous oxide was successfully developed in this study. The amorphous sorbent was aggregate of nanoparticles with a high surface area of 213m2g-1. Our sorption experiments showed that the nano-scale particles could effectively oxidize As(III) to As(V) and greatly remove both As(V) and As(III). The maximal adsorption capacities of As(V) and As(III) were 80 and 104mgg-1 at pH 5.0, respectively. As(V) uptake may be mainly achieved through replacement of hydroxyl groups and sulfate anions on the surface of the oxide and formation of inner complexes. The As(III) removal was essentially due to a sorption coupled with oxidation process; the MnO2 was mainly responsible for oxidization of As(III) to As(V) that was subsequently adsorbed onto ZrO2. © 2012 Elsevier Inc. Source

Li G.,CAS Yantai Institute of Coastal Zone Research | Li G.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | Gao S.,Yantai University | Zhang G.,CAS Yantai Institute of Coastal Zone Research | And 2 more authors.
Chemical Engineering Journal | Year: 2014

Phosphate is one of the main elements causing eutrophication and hence the development of high-efficiency and low-cost technologies for phosphate removal from water is of vital importance to alleviate the situation. In this study, nanostructured Fe-Cu binary oxides were synthesized via a facile coprecipitation process and its performance on phosphate removal was systematically evaluated. The as-prepared adsorbent with a Cu/Fe molar ratio of 1:2 was proved to possess the highest phosphate adsorption capacity. The adsorption isotherm data gave better fit to the Langmuir model, with a maximum phosphate adsorption capacity of 35.2mgg-1 at pH 7.0±0.1. Kinetic data correlated well with the pseudo-second-order kinetic model, indicating that the adsorption process might be chemical sorption. Thermodynamic data validated that the phosphate adsorption was an endothermic process. The solution pH has a big impact on the phosphate adsorption on the sorbent and acidic condition was favorable for the adsorption. The coexisting Cl-, SO42- and HCO3- anions had no significant influence on phosphate adsorption, while the present F- and SiO32- could suppress its adsorption, especially at high concentration level. The phosphate adsorption might be mainly achieved by the replacement of surface sulfate and hydroxyl groups by the phosphate species and formation of inner-sphere surface complexes at the water/oxide interface. Moreover, the spent Fe-Cu binary oxide could be effectively regenerated by NaOH solution for reuse. The high phosphate uptake capability and good reusability of the Fe-Cu binary oxide make it a potentially attractive adsorbent for the removal of phosphate from water. © 2013 Elsevier B.V. Source

Ma J.,Qingdao Technological University | Lu W.,Qingdao Technological University | Lu W.,Chinese Academy of Sciences | Lu W.,Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes | And 4 more authors.
Current Analytical Chemistry | Year: 2012

Dispersive liquid-liquid microextraction (DLLME) is a novel microextraction technique with a great potential in sample pretreatment, which has been increasingly used for preconcentration of diverse analytes. This review updates the state of the art and discusses promising prospects of DLLME, especially focuses on its combined use with chromatographic techniques for organic compounds analysis in environmental water samples. General and specific concepts of the fundamental theory of DLLME are described, and examples of recent innovations and applications are provided to demonstrate its potential for the determination of a wide range of organic compounds in various water matrices. Moreover, some limitations related to DLLME are also discussed in detail, and an outlook on the future of the technique, specifically its coupling with other pretreatment approaches, separation and detection techniques, is also given. © 2012 Bentham Science Publishers. Source

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