Numerical Simulation of Pore Water Distribution Under Electric Field in Unsaturated Soils

A numerical model predicting the moisture distribution under external electric field in unsaturated soils is established. Key parameters including matric potential, hydraulic and electrical permeability coefficient and electric conductivity are discussed. The simulation results are in good agreement with the measured data from literaturea, which verify exactness and suitability of the model. In general, the moisture contents decrease with time under the action of external electric force and matrix suction. A slight increase in moisture contert was observed in the anodic area at the beginning of the treatment. The electro-osmosis treatment effect can be enhanced by improving the voltage gradient or weaken the voltage loss at electrode. The limit value of electroosmosis treatment in moisture content is observed and the method can only be applied on the soil with moisture content higher than the limit value.

Degradation of Dibutyl Phthalate Plasticizer in Water by High-Performance Iro2-Ta2O5/Ti Electrocatalytic Electrode

Dibutyl phthalate (DBP) in the presence of a wastewater system is harmful to the environment and interferes with the human’s endocrine system. For wastewater treatment, DBP is very difficult to be decomposed by biotechniques and many catalytic processes have been developed. Among them, the electrocatalytic oxidation (EO) technique has been proven to possess high degradation efficiency of various organic compounds in wastewater. In this study, an electrocatalytic electrode of iridium-tantalum/titanium (IrO2-Ta2O5/Ti) was employed as the anode and graphite as the cathode to decompose DBP substances in the water. According to experimental results, the high removal efficiency of DBP and total organic carbon (TOC) of 90% and 56%, respectively, could be obtained under a voltage gradient of 10 V/cm for 60 min. Compared with other photocatalysis degradation, the IrO2-Ta2O5/Ti electrode could shorten about half the treatment time and electric power based on the same removal efficiency of DBP (i.e., photocatalysis requires 0.225~0.99 KWh). Results also indicated that the production of hydroxyl radical (•OH) in the electrocatalytic electrode played a key role for decomposing the DBP. Moreover, the pH and conductivity of water containing DBP were slightly changed and eventually remained in a stable state during the EO treatment. In addition, the removal efficiency of DBP could still remain about 90% after using the IrO2-Ta2O5/Ti electrode three times and the surface structure of the IrO2-Ta2O5/Ti electrode was stable.

V-type H+ ATPase Activity is Required for Embryonic Dorsal-Ventral Symmetry Breaking

The mechanism for embryonic dorsal-ventral (DV) symmetry breaking is idiosyncratic to the species, then converges on polarized expression of BMP signaling ligands. Here, we show that V-ATPase (VHA) activity is an early requirement for DV symmetry breaking in sea urchin embryos. In these basal deuterostomes, DV specification is mediated by ventral Nodal expression that leads to the establishment of a BMP signaling gradient. Nodal expression occurs downstream from p38 MAPK, which is transiently asymmetrically active. We show that VHA activity is required for DV symmetry breaking upstream from both p38 MAPK and Nodal. We rescue VHA-mediated ventralization by enforcing Nodal signaling asymmetry. We identify a VHA-dependent DV voltage gradient and also find that VHA activity is required for hypoxia inducible factor (HIF) activation. However, neither hyperpolarization nor HIF activation account for the dorsalizing effects of VHA, implicating a third unknown pathway that connects VHA activity to p38 MAPK symmetry breaking.

Pollution Flashover Characteristics of Composite Crossarm Insulator with a Large Diameter

The composite crossarm insulator differs greatly from the suspension insulator in structure and arrangement. This study aims to determine the pollution flashover characteristics of composite crossarm insulators under different voltage grades. Four types of AC composite crossarm insulators with diameters ranging from 100 mm to 450 mm are subjected to artificial pollution test, and then the effects of the surface hydrophobicity state of silicone rubber, core diameter, umbrella structure, arrangement, and insulation distance on the pollution flashover voltage of the composite crossarm insulators are analyzed. Under the pollution grade 0.2/1.0 mg/cm2 and voltage grade from 66 kV to 1000 kV, if the silicone rubber surface changes from HC5 to HC6, the pollution flashover voltage of the composite crossarm insulator will increase by 13.5% to 21.0% compared with the hydrophilic surface. If the core diameter changes from 100 mm to 300 mm, the pollution flashover voltage gradient decreases with the increase in core diameter; if the core diameter changes from 300 mm to 450 mm, the pollution flashover voltage gradient increases with core diameter. Under the same insulation height and core diameter, the umbrella structure will have a certain impact on pollution flashover voltage by up to 1.7% to 5.4%. Under the horizontal arrangement, the pollution flashover voltage can increase by 10.5% to 12.1% compared with that under the vertical arrangement. Under the hydrophilic surface and weak hydrophobicity state, the pollution flashover voltage has a linear relationship with the insulation distance. The above results can provide a reference for the structural design and optimization of the composite crossarm insulator.

A Review of Reduction Methods of Impact of Common-Mode Voltage on Electric Drives

In this survey paper, typical solutions that focus on the reduction in negative effects resulting from the common-mode voltage influence in AC motor drive applications are re-examined. The critical effectiveness evaluation of the considered methods is based on experimental results of tests performed in a laboratory setup with an induction machine fed by an inverter. The capacity of a common-mode voltage level reduction and voltage gradient du/dt limitation is discussed to extend motor bearings’ lifetime and increase motor windings’ safety. The characteristic features of the described solutions are compared and demonstrated using laboratory results.

Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia using standardized voltage mapping system protocol

Funding Acknowledgements Type of funding sources: None. Background according to European guidelines, ablation has become the treatment of choice in patients with symptomatic atrioventricular nodal reentry tachycardia (AVNRT). Despite the high procedure success rate, anatomical variations can affect the outcome in terms of relapses and complications. As recently demonstrated, low-voltage bridge visualization allows low pathway identification and therefore a new ablation strategy. Purpose our purpose was the validation of standardized ablation protocol within the low-voltage bridge area. Methods 70 consecutive patients with inducible AVNRT were evaluated and a three-dimensional voltage map of the right atrial septum and Koch Triangle was constructed by means of contact mapping. Ablation site was identified as the low-voltage area below the His bundle, adjusting the high-voltage slider to 1,5 mV and dynamically adjusting the slider of low-voltage. Radio-frequency energy (with an average number of nine lesions per patient) was then delivered within this area until the appearance of junctional beats. The results were tested at the end of the procedures and during the observational period (the mean follow-up was 10,5 months). Results the slow pathway was identified by the low-voltage bridge in 60 patients (85,6%) and in these patients, the target lesions in that area finally prevented induction of AVNRT in 100% of cases. A zero-fluoroscopy approach was possible for 50 patients (83%). Compared with standard AVNRT ablation, no complications as well as no statistical differences in terms of total procedure time were observed (p = 0,056). 59 patients (98%) had no relapses during the follow-up. Conclusions voltage gradient mapping successfully targeted the slow pathway in most of our cases. Lesions on the voltage bridge led to effective ablation of AVNRT and to a drastic x-ray exposure reduction in the absence of acute or long-term complications. Abstract Figure. Last lesion on low-voltage bridge.