Thermodynamics of irreversible processes and quantum field theory: An interplay for the understanding of ecosystem dynamics

Ecological modelling has not yet received from basic “hard” sciences, like conventional physics and chemistry, an adequate conceptual support. Mechanistic simulation techniques are very far from achieving a satisfactory understanding of ecosystem dynamics.     

光驱动CQDs/PCN催化活化过硫酸盐降解双酚A

以柠檬酸和尿素为原料制备了碳量子点(CQDs),并采用热聚合法将CQDs分散在聚合物氮化碳(PCN)纳米片的表面(CQDs/PCN).通过SEM、TEM、XRD等测试技术对所制备的材料进行表征,证明了CQDs成功负载在PCN上.在模拟太阳光的条件下,考察了CQDs/PCN光催化活化过硫酸盐(PDS)对双酚A(BPA)的光催化性能.结果表明BPA在10min时降解率达到99.99%,且重复使用4次后仍能去除85%以上的BPA,说明该材料具有良好的重复性与稳定性.自由基猝灭实验表明CQDs/PCN-PDS光催化过程主要通过超氧自由基(·O₂^ˉ)、单线态氧(¹O₂)和空穴(h⁺)的作用降解BPA,推测了CQDs/PCN-PDS光催化去除BPA可能的反应机理.此外,通过分析光催化氧化中间产物,提出了BPA可能的降解路径.本研究为BPA的快速、高效降解提供了可能性,也为BPA降解提供了一种新的思路.     

量子点在环境污染物检测中的应用进展

作为一类理想的荧光探针，量子点近年来在环境污染物定性定量分析方面的应用取得了很大进展，为环境监测提供了一种新的方法和技术，显示出极大的优越性。综述了量子点分子印迹、量子点自组装膜、双色量子点比率荧光传感等新技术在国内外环境污染物检测方面的研究进展，并对其发展前景作了展望。     

Effect of natural organic matter and green microalga on carboxyl-polyethylene glycol coated CdSe/ZnS quantum dots stability and transformations under freshwater conditions

The influence of pH, ionic strength, presence of humic or alginic acids, extracellular polymeric substances (EPS), or freshwater microalga Chlorella kesslerii on the stability and transformation of carboxyl-PEG-CdSe/ZnS core/shell quantum dots (QDs) in terms of number, hydrodynamic size and fluorescence of individual particles, was studied by fluorescence correlation spectroscopy. Obtained results demonstrated that QDs form stable dispersions at nanomolar concentrations under conditions typical for freshwaters. The presence of 5 or 15 mg C L⁻¹ of humic acid or 50 mg C L⁻¹ EPS did not significantly affect these parameters. In contrast, 5 or 50 mg C L⁻¹ alginate at ionic strength of 10 mM shifted the hydrodynamic radius toward larger values, suggesting a possible capture of QDs by the linear alginate chains. The addition of microalga to the QD dispersions resulted in a slight reduction of the number of QDs and a significant decline in the fluorescence of individual QDs.     

Water chemistry influences on long-term dissolution kinetics of CdSe/ZnS quantum dots

Widespread usage of engineered metallic quantum dots(QDs) within consumer products has evoked a need to assess their fate within environmental systems.QDs are mixed-metal nanocrystals that often include Cd~(2+)which poses a health risk as a nanocrystal or when leached into water.The goal of this work is to study the long-term metal cation leaching behavior and the factors affecting the dissolution processes of mercaptopropionic acid(MPA) capped CdSe/ZnS QDs in aphotic conditions.QD suspensions were prepared in different water conditions,and release of Zn2+and Cd~(2+) cations were monitored over time by size exclusion chromatography-inductively coupled plasm a-mass spectrometry.In most conditions with dissolved 02 present,the ZnS shell degraded fairly rapidly over～1 week,while some of the CdSe core remained up to 80 days.Additional MPA,Zn~(2+),and Cd2+temporarily delayed dissolution,indicating a moderate role for capping agent detachment and mineral solubility.The presence of H_2 O_2 and the ligand ethylenediaminetetraacetate accelerated dissolution,while NOM had no kinetic effect.No dissolution of CdSe core was observed when 02 was absent or when QDs formed aggregates at higher concentrations with 02 present.The shrinking particle model with product layer diffusion control best describes Zn2+and Cd~(2+) dissolution kinetics.The longevity of QDs in their nanocrystal form appears to be partly controlled by environmental conditions,with anoxic,aphotic environments preserving the core mineral phase,and oxidants or complexing ligands promoting shell and core mineral dissolution.     

碲化镉量子点对小鼠肝脏超微结构及重要生物酶活性的影响

探讨了碲化镉量子点(cadmium telluride quantum dots,CdTeQDs)对小鼠肝组织超微结构及琥珀酸脱氢酶(succinate dehydrogenase,SDH)和三磷酸腺苷酶(adenosine triphosphatase,ATPase)活性的影响。将20只雄性ICR小鼠随机分成QDs染毒组和对照组,采用尾静脉注射方式进行一次性染毒,染毒组每只小鼠注射2μmol·kg-1体重的CdTeQDs(以Cd~(2+)的摩尔浓度计算)。每5只为一组分别在染毒后的1 d、3 d和7 d处死小鼠,另外5只注射生理盐水作为对照组。取部分肝组织在透射电镜下观察其超微结构变化并使用试剂盒测定肝脏中SDH、Na~+/K~+-ATP酶、Ca~(~(2+))/Mg~(2+)-ATP酶的活性。结果显示CdTeQDs暴露后染毒组小鼠肝细胞胞浆疏松,线粒体出现肿胀、空泡、嵴减少等结构变化,表明肝细胞受到损伤且染毒1 d后损伤最严重;肝脏中染毒组SDH活性与对照组相比显著降低(P0.05);染毒1 d后,Na~+/K~+-ATP酶和Ca~(2+)/Mg~(2+)-ATP酶活性与对照组相比显著升高,随着染毒后时间的延长,其活性呈现下降的变化趋势。单次量注射CdTeQDs能够引起小鼠肝脏损伤,抑制SDH活性,引起ATP酶活性改变,这些症状在暴露时间内呈现恢复趋势。     

硫化镉量子点对人胚肝细胞L-02的毒性研究(Cadmium Sulfide Quantum Dots Induce Cytotoxicity in Human Embryo Liver Cells)

采用乳化液膜法自组合成硫化镉量子点(CdS quantum dots,CdS QDs),探讨CdS QDs的体外毒性作用及可能的作用机制.选用人胚肝细胞(L-02)作为细胞模型,采用不同浓度的CdS QDs(0.00、1.25、2.50、5.00、10.00、20.00、40.00μg·mL-1)对L-02细胞进行染毒.24h后,检测细胞内乳酸脱氢酶(LDH)释放量、谷胱甘肽(GSH)含量和超氧化物歧化酶(SOD)活力,并比较加入抗氧化剂N-乙酞半胱氨酸(NAC)后细胞存活率的变化,同时测定了细胞内外的镉离子浓度.结果表明,与空白对照组相比,CdS QDs单独染毒组细胞存活率显著降低(p<0.05或p<0.01);加入抗氧化剂NAC后,10.00、20.00、40.00μg·mL-1染毒组细胞存活率与单独染毒组相比显著上升(p<0.01).CdS QDs浓度为5.00μg·mL-1时,细胞内Cd2+的浓度略高于细胞外Cd2+的浓度,在其他浓度下,细胞外Cd2+的浓度均显著高于细胞内Cd2+的浓度.当作用浓度上升至10.00μg·mL-1时,人胚肝细胞内LDH含量显著增加,且随着作用剂量的升高,LDH含量逐渐增加.与空白对照组相比,40.00μg·mL-1CdS QDs染毒组SOD活力和20.00μg·mL-1CdS QDs染毒组GSH含量均显著降低(p<0.05).Cd2+易透过L-02细胞的细胞膜而进入细胞内,从而造成细胞损伤.氧化损伤可能是CdSQDs对L-02细胞毒性作用的机制之一.     

碲化镉量子点对小鼠睾丸组织的氧化损伤（Effects of CdTe Quantum Dots on the Antioxidant Enzymes Activity and Lipid Peroxidation in Testes of Mice）

为探讨碲化镉量子点(CdTeQDs)对小鼠睾丸的急性氧化损伤作用,将20只雄性ICR小鼠随机分成4组:对照组、1d、3d、7d(3个不同时间组),采用尾静脉注射进行一次性染毒2.5μmol·kg-1CdTeQDs,对照组注射等体积生理盐水.染毒后对睾丸的脏器系数以及组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)活性,丙二醛(MDA)含量分别进行测定,从而检测CdTeQDs对睾丸组织的急性氧化损伤作用.结果显示,与对照组相比,随染毒时间的延长,睾丸脏器系数无显著性变化(p>0.05);GSH-Px和SOD活性随染毒时间的延长呈逐渐升高趋势;而CAT活性呈逐渐降低趋势,且与对照组差异显著(p<0.01);MDA含量显著高于对照(p<0.01),且随时间变化不大.CdTeQDs染毒可导致小鼠睾丸组织氧化损伤,其损伤程度与染毒时间之间具有一定的时间-效应关系.     

微米级核壳量子点团聚体在生物膜中的扩散与溶解及其毒性

包括量子点在内的人工纳米颗粒是近年来突出的环境污染物,为确定其在生物膜中的扩散过程和特征,应用TIRF（全内反射荧光）、FRAP（荧光漂白后恢复）等技术,研究了CdTe/CdS/ZnS核壳式量子的微米级的团聚体在细菌Comamonas testoteroni生物膜表面的吸附动力学、生物膜内部的扩散及其在生物膜中的溶解和毒性.结果表明:通过TIRF技术观察到生物膜可快速吸附>1 μm的CdTe/CdS/ZnS核壳式量子点团聚体,而且通过CLSM（激光扫描共聚焦荧光显微镜）进行深度扫描发现,量子点团聚体吸附到生物膜表面后可以进一步扩散到生物膜深层,在25 min内可穿透45 μm的生物膜,并在生物膜中随深度呈线性分布特征.FRAP分析表明,量子点团聚体被生物膜固定后还具有较强的移动性,漂白区的荧光强度在5 min可恢复30%.量子点团聚体在生物膜中会溶解产生Cd2+、Zn2+等重金属离子,从而对生物膜产生毒性并杀死细菌.研究显示,虽然纳米颗粒进入环境中会形成微米级的团聚体,但依然可以进入生物膜,对水生微生物生态系统产生危害.TIRF、CLSM和FRAP技术是研究纳米颗粒物在生物膜表面吸附和内部扩散动力学的有效工具.      

Extraction of 17β-estradiol in water using non-imprinted polymer submicron particles in membrane filters

17β-Estradiol (E2) is an endocrine disrupting chemical of harm to both animals and human beings at a low concentration level (ng/L). It cannot be completely removed by wastewater treatments, and is often detected in both environment and drinking waters. The purpose of this feasibility study, towards environmental engineering in the field of water analysis and treatment, was to remove E2 by extraction using non-imprinted polymer (NIP) submicron particles. Experimental results showed that 0.5 mg/L of E2 could be completely extracted by adding 10 mg of NIP particles directly into 10 mL of water. However, the extraction efficiency decreased to 64% for 100 mL of water. prefilling the NIP particles inside a membrane filter showed a potential for water treatment of a large volume, requiring no effort to distribute the particles uniformly in the water. High extraction efficiency (80 ± 10)% for E2 was achieved for 100 mL of water. A total mass of 0.29 mg E2 was extracted from 1000 mL of water containing 0.8 mg/L E2 (by using only 10 mg of NIP particles). Both efficiency and mass capacity can be increased, by scaling up the amount of NIP particles, towards environmental engineering applications.