[Pylorus-preserving gastrectomy and segmental gastrectomy: discrimination of concepts and surgical procedures]

Both pylorus-preserving gastrectomy (PPG) and segmental gastrectomy (SG) achieve the preservation of gastric cardia and pylorus through the circumferential resection of stomach, while concepts and surgical procedures of these two operations are obviously different. In this sense, transectional gastrectomy includes both PPG and SG. PPG is one of the standard surgical procedure for early gastric cancer (EGC). The extent of lymph node dissection (No.1, 3, 4sb, 4d, 6, 7, 8a, 9) and the retention of infrapyloric vessels, hepatic and pyloric branch of vagal nerve has formed a consensus. Meanwhile, SG is regarded as an investigational treatment according to the Japanese gastric cancer treatment guidelines. It is still controversial and may generate an ethical risk in the clinical practice. This article distinguishes the difference in the concepts and surgical procedures between PPG and SG, assisting a comprehensive evaluation in further research.

[Segmental gastrectomy with cardia preservation for early gastric cancer]

Segmental gastrectomy with cardia preservation can reduce the symptoms of postoperative gastroesophageal reflux and improve the quality of life, which is potentially advantageous among function-preserving gastrectomy procedures. However, due to the limited extent of excision, this procedure is classified as an investigational treatment in the Japanese Gastric Cancer Treatment Guidelines, without wide acceptance in clinical practice. It is generally believed that the surgical indication of segmental gastrectomy is more selected compared to the pylorus-preserving gastrectomy, and there are also differences between their therapeutic goals. The indications of cardia preservation in segmental gastrectomy mainly depend on the T stage, the distance of the resection margin and the metastasis of lymph nodes. Other points of segmental gastrectomy mainly include the scope of lymphadenectomy, the preservation of blood vessels and vagal nerves, which are still controversial in different researches. High-quality evidences are needed to confirm the safety and long-term efficacy of the segmental gastrectomy.

Optimization for municipal solid waste treatment based on energy consumption and contaminant emission

This paper analyzes the characterization of energy consumption and contaminant emissions from a municipal solid waste (MSW) treatment system that comprises transfer station, landfill site, combustion plant, composting plant, dejecta treatment station, and an integrated MSW treatment plant. The consumed energy and energy medium materials were integrated under comprehensive energy consumption (CEC) for comparison. Among typical MSW disposal methods such as combustion, composting, and landfilling, landfilling has the minimum CEC value. Installing an integrated treatment plant is the recommended MSW management method because of its lower CEC. Furthermore, this method is used to ensure process centralization. In landfill sites, a positive linear correlation was observed between the CEC and contaminant removal ratios when emitted pollutants have a certain weight coefficient. The process should utilize the minimum CEC value of 5.3702 kgce/t MSW and consider energy consumption, energy recovery, MSW components, and the equivalent of carbon dioxide emissions.