[Enhanced Electrokinetic Remediation of Heavy Metals Contaminated Soils by Stainless Steel Electrodes as well as the Phenomenon and Mechanism of Electrode Corrosion and Crystallization].

Electrode corrosion and salt crystallization are important challenges that restrict the engineering application of electrokinetic technology. In the present study, using stainless steel as an electrode, and deionized water (DW), citric acid (CA) and polyaspartic acid (PASP) as electrolytes, Pb/Cu-contaminated soil was remediated by electrokinetic. All of the EK experiments were conducted in a 2 L soil cell reactor with a moisture level of about 35% blended with 1000 mg·g-1 of Pb and 778 mg·g-1 of Cu under a constant voltage gradient (1 V·cm-1, 2 V·cm-1) for 150 h. The removal efficiency of heavy metals and influencing factors, as well as the phenomenon and mechanism of electrode corrosion and salt crystallization were explored. The experimental results showed under the action of electric field, the Ca in the test soil would move to the cathode, and the crystal was formed in the alkaline condition. Additionally, the conductivity of the electrode was reduced. During the EK process, water at the anode was primarily oxidized, undergoing a reduction reaction at the cathode. Because H+ and OH- were transported through the soil by electromigration and electro-osmotic flow (EOF), changes in soil pH could occur. The concentrations distribution of Pb-Cu appeared to be related to the distribution of soil pH in the cell, which might be associated with the desorption and hydroxide precipitation of Pb-Cu. PASP resulted in obvious inhibitory effect on the corrosion of stainless steel electrode, CA and PASP could clearly destroy the formation of CaCO3 crystal, while barely effectively disrupted the formation of Ca (OH)2 crystal. Both CA and PASP could promote the removal of Pb, but the influence of PASP on the removal of Cu was not obvious, and the effect of CA was very significant. Combined with different corrosion inhibitor and reinforcing agent, stainless steel can be chosen as the engineering application electrode in electrokinetic remediation.

[Clinical analysis of missed diagnosis of duodenal injury in 9 cases].

OBJECTIVE: To study the reasons and possibly solutions for missed diagnosis of duodenal injury. METHOD The clinical records were retrospectively analyzed in 9 cases of missed diagnosis of duodenal injury treated in our hospital in the year 1992 to 2002. RESULTS Of the 15 cases of duodenal injury, missed diagnoses occurred in 9 cases. The reasons for the missed diagnoses included complications by injuries of the other abdominal organs that concealed duodenal injuries, neglect of the light injuries, and the lack of clinical experience on the part of the young doctors. CONCLUSION Duodenal injury frequently occurs along with other abdominal organ injuries and is easy to escape detection, which can be avoided by careful preoperative examination of the characteristics of injuries and the patients' clinical manifestations after the injury.