The cadmium–mercaptoacetic acid complex contributes to the genotoxicity of mercaptoacetic acid-coated CdSe-core quantum dots

Quantum dots (QDs) have many potential clinical and biological applications because of their advantages over traditional fluorescent dyes. However, the genotoxicity potential of QDs still remains unclear. In this paper, a plasmid-based system was designed to explore the genotoxic mechanism of QDs by detecting changes in DNA configuration and biological activities. The direct chemicobiological interactions between DNA and mercaptoacetic acid-coated CdSecore QDs (MAA–QDs) were investigated. After incubation with different concentrations of MAA–QDs (0.043, 0.13, 0.4, 1.2, and 3.6 μmol/L) in the dark, the DNA conversion of the covalently closed circular (CCC) DNA to the open circular (OC) DNA was significantly enhanced (from 13.9% ± 2.2% to 59.9% ± 12.8%) while the residual transformation activity of plasmid DNA was greatly decreased (from 80.7% ± 12.8% to 13.6% ± 0.8%), which indicated that the damages to the DNA structure and biological activities induced by MAA–QDs were concentration-dependent. The electrospray ionization mass spectrometry data suggested that the observed genotoxicity might be correlated with the cadmium–mercaptoacetic acid complex (Cd–MAA) that is formed in the solution of MAA–QDs. Circular dichroism spectroscopy and transformation assay results indicated that the Cd–MAA complex might interact with DNA through the groove-binding mode and prefer binding to DNA fragments with high adenine and thymine content. Furthermore, the plasmid transformation assay could be used as an effective method to evaluate the genotoxicities of nanoparticles

Regeneration capacity of small clonal fragments of the invasive Mikania micrantha H.B.K.: effects of burial depth and stolon internode length.

The perennial stoloniferous herbaceous vine Mikania micrantha H.B.K. is among the most noxious exotic invaders in China and the world. Disturbance can fragment stolons of M. micrantha and disperse these fragments over long distances or bury them in soils at different depths. To test their regeneration capacity, single-node stolon fragments with stolon internode lengths of 0, 3, 6 and 12 cm were buried in soil at 0, 2, 5 and 8 cm depths, respectively. The fragments were growing for nine weeks, and their emergence status, growth and morphological traits were measured. The results indicated that increasing burial depth significantly decreased survival rate and increased the emergence time of the M. micrantha plants. At an 8-cm burial depth, very few fragments (2.19%) emerged and survived. Burial did not affect the total biomass and root to shoot ratio of the surviving M. micrantha plants that emerged from the 0- and 2-cm burial depths. Increasing internode length significantly increased survival rate and growth measures, but there was no interaction effect with burial depth for any traits measured. These results suggest that M. micrantha can regenerate from buried stolon fragments, and thus, disturbance may contribute to the spread of this exotic invader. Any human activities producing stolon fragments or facilitating dispersal should be avoided

Fault diagnosis for multiple current sensors in grid‐connected inverter based on average modulation voltage

International audienceAbstract Grid‐connected inverters are the core equipment in the renewable power system. There are multiple current sensors which may affect the driving module of the switch in inverter. In multiple current sensor fault diagnosis, the coupling between fault components makes fault diagnosis difficult. This paper presents an offset fault diagnosis method of multiple current sensors based on the average modulation voltage model. Based on the influence of current sensor offset fault in the system, the average modulation voltage model is established in three‐phase stationary coordinates. The difference between the measured value of the current and the actual value is estimated through the model when the offset fault occurs. And then the fault is located. Experimental results show that the fault can be located accurately and fault tolerant control can be performed by this method when there are offset faults in multiple sensors simultaneously

A Fault Tolerance Method for Multiple Current Sensor Offset Faults in Grid-Connected Inverters

International audienceThree-phase grid-connected inverters have been widely used in the distributed generation system, and the current sensor has been applied in closed-loop control in inverters. When the current sensor offset faults occurs, partial fault features of multiple current sensors disappear from the closed-loop control grid-connected system, which leads to difficulties for fault diagnostics and fault-tolerant control. This paper proposes a fault tolerance method based on average current compensation mode to eliminate these adverse effects of fault features. The average current compensation mode compensates the average of the three-phase current to the αβ axis current to realize the fault feature reconstruction of the current sensor. The mode does not affect the normal condition of the system. Then, the data-driven method is used for fault diagnosis, and the corresponding fault tolerant control model is selected according to the diagnosis results. Finally, the experimental results show that the proposed strategy has a good fault tolerance control performance and can improve the fault feature discrimination and diagnostic accuracy

Effects of burial depth and stolon internode length on growth of <i>Mikania micrantha</i>.

<p>Total biomass, leaf biomass, stolon biomass and root biomass of the surviving fragments are given. Error bars represent the mean ± SE. One-way ANOVAs with post-hoc Duncan’s tests were used for the multiple comparison analyses (data were ln-transformed prior to analyses), and significant differences (at the significance level of <i>P</i>=0.05) between two treatments are marked with the use of different symbols.</p

Effects of burial depth and stolon internode length on morphology of <i>Mikania micrantha</i>.

<p>Root to shoot ratio and shoot height are given. Error bars represent the mean ± SE. One-way ANOVAs with post-hoc Duncan’s tests were used for the multiple comparison analyses (data on root to shoot ratio were first multiplied by 10 and then ln-transformed prior to analyses), and significant differences (at the significance level of <i>P</i>=0.05) between two treatments are marked with the use of different symbols.</p

Effects of burial depth and stolon internode length on emergence rate, emergence time and survival rate of <i>Mikania micrantha</i>.

<p>Emergence time is the number of days between planting and emergence. Error bars represent the mean ± SE. One-way ANOVAs with post-hoc Duncan’s tests were used for the multiple comparison analyses (data on emergence time were ln-transformed prior to analyses), and significant differences (at the significance level of <i>P</i>=0.05) between two treatments are marked with the use of different symbols.</p