The Factors for Transformation between the Fractions of Speciation of Trace Metals in Lake Sediments

Objective Despite the fact that the bioavailability of trace metals indicated by their speciation has been an indispensable parameter in the assessment and treatment of the environmental pollution of trace metals, many studies have suggested that the bioavailability of trace metals may change according to the conditions of the environment, and the speciation of trace metals can also transform between some fractions. These transformations are related with these factors such as the compositions, microorganism, time, and other physical-chemical conditions of the system. Our work aims to systematically investigate and probe the factors to affect the transformation aside from analysis at certain time-place. The results of these understanding and investigations can be used for reasonably determining the allocation of financial and technical resources in natural and engineered processes, with bringing about inspirations from the evolution of the speciation of the trace metals on environmental impacts.

Effects of organic acids on heavy metal release or immobilization in contaminated soil

In order to explicit the environmental activity of heavy metals affected by different organic acids in soil,a batch incubation experiment was explored to investigate the influence of high relative molecular mass organic acid(HMWOA)(humic acid and fulvic acid)and low relative molecular mass organic acid(LMWOA)(threonic acid and oxalic acid)on the release or immobilization of Pb,Cu and Cd in soils.Results showed that LMWOA,especially threonic acid,had a good performance in the release of Pb,Cu and Cd from soils,and decrease in the fractions of HOAc-extractable,reducible and oxidable Pb,Cu and Cd.Conversely,HMWOA,especially humic acid,decreased the release of Pb,Cu and Cd,while it increased the fractions of HOAc-extractable,reducible and oxidable Pb,Cu and Cd,indicating that HMWOA can immobilize heavy metals.The release of Pb,Cu and Cd caused by LMWOA was attributed to the dissociation of soil organic matter and amorphous iron oxides since the total organic carbon and the water-soluble iron increased.The immobilization of Pb,Cu and Cd by HMWOA was attributed to the adsorption onto HMWOA followed by amorphous iron since HMWOA resulted in a significant decrease of zeta potential and an increase of amorphous iron oxide.It can be concluded that LMWOA has a potential application in soil washing remediation,while HMWOA can be used in the immobilization remediation for heavy metals contaminated soils.

Insulator-metal transition in CaTiO3 quantum dots induced by ultrafast laser pulses

According to time-dependent density functional theory(TDDFT),we study the interactions between ultra-fast laser pulses and two kinds of calcium titanate quantum dots(PCTO-QDs and MCTO-QDs).Under the action of localized field effect,ultrafast laser can induce quantum dots to make the transition from insulator to metal.The PCTO-QDs are ultimately metallic,while the MCTO-QDs are still insulator after experiencing metal state.This is bacause the stability of the unsaturated atoms in the outermost layer of PCTO-QDs is weak and the geometric configuration of MCTO-QDs as a potential well will also reduce the damage of laser.Moreover,laser waveforms approaching to the intrinsic frequency of quantum dots tend to cause the highest electron levels to cross the Fermi surface.In this paper,it is reported that the insulating quantum dots can be transformed into metal by adjusting the intensity and frequency of laser.The importance of local morphology is emphasized by comparing two kinds of CTO-QDs.More importantly,it is an important step to identify the potential properties of perovskite materials.

STUDY ON THE EFFECT OF SEDIMENT MOTION ON TRANSPORT TRANSFORMATION OF HEAVY METAL POLLUTANTS

By combining laboratorial experiments,theoretical analysis and mathematical model,theeffect of sediment motion on transport-transformation of heavy-metal pollutants is studied. (1)Previous studies on adsorption-desorption of heavy-metal pollutants by sedimentparticles are systematically summarized.Based on this summary,subjects that need to be furtherstudied are put forward. In rivers most heavy-metal pollutants concentrate on sediment particles.In order tocontrolling water pollution aused by heavy-metal pollutants following topics should beemphasized:studies on the effect of suspended matter and deposit on transport-transformation of

Numerical Simulation on Thermal Response of Laser-Irradiated Biological Tissues Embedded with Liquid Metal Nanoparticles

Photothermal therapy is emerging as a very promising way for minimally invasive cancer treatment.To enhance thermal energy deposition of laser in target malignant tissues,liquid metal nanoparticles(LMNPs)have been recently identified as completely unprecedented photothermal sensitizers due to their unique physicochemical properties and superior photothermal conversion rate under near-infrared(NIR)laser irradiation.However,there is currently a strong lack of understanding of the laser energy distribution and the transient temperature field within the biological tissues,which would seriously hinder the development of LMNPs assisted photothermal therapy.Therefore,this paper focused on the distinctive photothermal effect of LMNPs embedded in biological tissues under NIR laser irradiation.The mathematical model coupling the Monte-Carlo photon transport model with Penne's bioheat transfer model has been established.Simulation studies have shown that LMNPs play an important role in enhancing the absorption of NIR laser,which contributes to local temperature rise and improves the temperature distribution.Comparing with the control case without LMNPs,the maximum temperature increases by nearly 1.0 time,the local temperature rise reaches 30℃ in 1.0 second.When the diameter and concentration of LMNPs are 40 nm and 1012/mm3,the resulting temperature variation and distribution is best for the effective killing of tumors without damaging normal tissues.In addition,the simulation results are meaningful for guiding the selection of laser irradiation time in conjunction with the cooling time,ensuring the controllable accuracy of treatment.To the best of our knowledge,the present study is one of the first attempts to quantify the influence of transformable LMNPs on the temperature distributions inside the biological tissues,showing important academic significance for guiding LMNPs assisted photothermal treatment.