Distribution characteristics and controlling factors of typical heavy metals in Huanghe River estuary,China

The geochemical characteristics and potential controlling factors of colloidal Zn,Cd,and Pb in Huanghe(Yellow)River estuary(HRE),China were investigated.The three metals were highly variable over a range of spatiotemporal scales,comprehensively forced by various physical and biological processes.Total dissolved Zn,Cd,and Pb varied from 200.1 to 321.7,2.6 to 4.1,and 0.5 to 1.0 nmol/L,respectively.Only one near-estuarine station of Zn had contamination factor values>1,which indicate the lower contaminant levels.Five dissolved species of Zn,Cd and Pb were fractionated,namely<1 kDa,1-3 kDa,3-10 kDa,10-100 kDa,and 100 kDa-0.45μm.The<1 kDa truly dissolved phase was the main fraction of the three dissolved metals(50%-62%),while the 100-kDa-0.45-μm high molecular weight colloidal fraction was dominant in their respective colloidal phase.Territorial input and sediment acted as important sources of strong ligands and natural colloids for the HRE water system.<3-kDa Zn and Pb were susceptible to the dissolved oxygen,the behaviors of colloidal Zn and 3-10-kDa Pb were related to dissolved organic carbon(DOC).However,no significant correlation between each dissolved fraction of Cd and salinity,pH,temperature,colloidal organic carbon,and DOC was found in this study.Overall,these findings,completed by the evaluation of the dissolved species of Zn,Cd,and Pb at 10 sites over the river-sea mixing zone,provided new insights into the colloidal heterogeneity that affect metals geochemical features,migration and fate in estuaries.

聚α-甲基苯乙烯空心微球的开裂机理

干燥过程是制备高表面质量聚α-甲基苯乙烯(PAMS)空心微球的关键过程之一。文中通过实验研究了不同热处理温度(55℃、75℃、95℃)和不同干燥温度(室温、45℃、65℃、85℃、100℃)对PAMS空心微球干燥过程的影响。实验结果表明,采用不同温度对PAMS空心微球进行热处理后,具有严重初始微缺陷的空心微球所占百分比没有显著差异。因为最高热处理温度(95℃)远远低于PAMS的玻璃化转变温度(≈180℃)而不能使PAMS分子链段运动以消除残余内应力。随着干燥温度的升高,干燥后的空心微球表面出现裂纹的比例相应增加。干燥温度的升高将会导致空心微球球壳所受应力不断增大。而球壳所受应力是其产生裂纹的主要原因之一。

Progress and challenges in the fabrication of DPS shells for ICF

To improve the quality of deuterated polystyrene(DPS)shells,the synthesis and purification of DPS as well as the fabrication of DPS shells are investigated.The molecular weight and molecular weight distribution,measured by GPC-MALLS,are about 350 kg mol^(-1) and less than 2.0,respectively.The results of TG and GC-MS indicate that the residual solvent is almost completely removed.DPS shells with;300 mm–2500 mmdiameter and;10 mm–100mmwall thickness are successfully prepared by a microfluidic device.The monodispersity of the diameter ismuchbetter than that of the wall thickness in a batch ofDPSshells.The vacuoles can be suppressed by both reducing hydrophilic residues in DPS and adding some salts into the outer water phase(W2).The defects appearing during the drying process decrease by heat treatment,ethanol exchange,and lowered drying temperature.The results presented in this work not only provide guidelines for the preparation of DPS shells of better quality,but also indicate challenges for the future.

Heavy metals in sediments of Yellow Sea and East China Sea: Chemical speciation,distribution,influence factor,and contamination

Metal species and the degree of environmental pollution are related to the hydrogen sulfide(H_(2)S),an important product of early diagenesis that can react with metals to form stable compounds.To investigate the eff ects of H_(2)S to metals and evaluate metal environment eff ect in the sediments of the East China Sea(ECS)and Yellow Sea(YS),geochemical characteristic and spatial distribution of nine heavy metals and H_(2)S profile were studied.Higher H_(2)S content and lower metal content was observed in the sediments 10 cm in depth in the North Yellow Sea and the west coast of South Korea.The pollution load index(I_(pl))indicates that the southern coast of Shandong Peninsula underwent moderate pollution(I_(pl)=1)of heavy metals and no heavy metal pollution appeared in other areas(I_(pl)<1).To some extents,the ecological risk of Cd and As enrichment was moderately severe in all stations.The chance of heavy metal combination to be toxic in ECS and YS during summer was 21%.In addition,correlation between H_(2)S content and metals in both solid and porewater phases was obvious,corroborating important eff ect of H_(2)S on metal distribution.Moreover,H_(2)S could aff ect the spatial distributions of heavy metals in porewater directly and be indicative of potential biological eff ects of combined toxicant groups in the study region.

Functional nanoemulsions: Controllable low-energy nanoemulsification and advanced biomedical application

Nanoemulsions are widely used as advanced pharmaceutical delivery systems in biomedical field, due to their high encapsulation efficiency and good therapy efficacy.Nanoemulsification techniques that produce nanoemulsions with controllable sizes and compositions are promising for creating advanced nanoemulsion systems for pharmaceutical delivery.This review summarizes recent advances on low-energy emulsification techniques for producing nanoemulsions, and the use of these nanoemulsions as advanced pharmaceutical delivery systems and as templates to create drug-loaded functional particles for biomedical application.First, nanoemulsification techniques that utilize elaborate interfacial physics/chemistry and micro-/nano-fluidics, featured with relatively-low energy input, to produce nanoemulsions with controllable sizes and compositions, are introduced.Uses of these nanoemulsions to create nanoemulsionincorporated milli-particles, drug-loaded nanoparticles and nanoparticle-incorporated microparticles with sizes ranging from several millimeters to sub-10 nm are emphasized.Flexible and efficient use of the nanoemulsions, functional nanoparticles and milli-/micro-particles integrated with nanoemulsions or nanoparticles for advanced pharmaceutical delivery in biomedical field are highlighted, with focus on how the interplay between their sizes and compositions achieve desired pharmaceutical-delivery performances.Finally, perspectives on further advances on the controllable production of nanoemulsions are provided.

Novel sulfhydryl functionalized covalent organic frameworks for ultra-trace Hg^(2+) removal from aqueous solution

Two kinds of novel sulfhydryl functionalized covalent organic frameworks were fabricated as adsorbents for the removal of ultra-trace concentrations of Hg^(2+)from water.The two kinds of sulfhydryl functionalized covalent organic frameworks were obtained via a thiol-ene click reaction between the thiol groups of trithiocyanuric acid(TTC)or bismuththiol(BMT)and vinyl groups on the surface of covalent organic frameworks.The material structure was characterized by XRD,SEM,EDS,FT-IR,BET,and TG analysis.Due to their rich sulfur content,both adsorbents(COF-SH-1 and COF-SH-2)exhibited a high level of selective Hg^(2+)removal from aqueous solution with maximum adsorption capacities of 763.4 mg g^(-1) and526.3 mg g^(-1),respectively.Furthermore,in the presence of ultra-low concentrations of Hg^(2+)both materials exhibited excellent performance,achieving rapid Hg^(2+)removal at concentrations from 10μg L^(-1) to less than 0.02 ng L^(-1).Analysis of the adsorption mechanism indicates that the sulfur containing chelating groups exhibit a strong binding capacity for Hg^(2+).Results show that the structure determines the performance,with the amount of adsorption sites being related to the adsorption capacity.Therefore,as sulfhydryl functionalized covalent organic frameworks contain an abundance of adsorption sites,these materials can effectively achieve the removal of ultra-low trace Hg^(2+)concentrations and have promising future application potential for the environmental detection of heavy metals.