The process of peritoneal metastasis involves the diapedesis of intra-abdominal exfoliated gastric cancer cells through the mesothelial cell monolayers; however, the related molecular mechanisms for this process are still unclear. Heterocellular gap-junctional intercellular communication (GJIC) between gastric cancer cells and mesothelial cells may play an active role during diapedesis. In this study we detected the expression of connexin 43 (Cx43) in primary gastric cancer tissues, intra-abdominal exfoliated cancer cells, and matched metastatic peritoneal tissues. We found that the expression of Cx43 in primary gastric cancer tissues was significantly decreased; the intra-abdominal exfoliated cancer cells and matched metastatic peritoneal tissues exhibited increasing expression compared with primary gastric cancer tissues. BGC-823 and SGC-7901 human gastric cancer cells were engineered to express Cx43 or Cx43T154A (a mutant protein that only couples gap junctions but provides no intercellular communication) and were co-cultured with human peritoneal mesothelial cells (HPMCs). Heterocellular GJIC and diapedesis through HPMC monolayers on matrigel-coated coverslips were investigated. We found that BGC-823 and SGC-7901 gastric cancer cells expressing Cx43 formed functional heterocellular gap junctions with HPMC monolayers within one hour. A significant increase in diapedesis was observed in engineered Cx43-expressing cells compared with Cx43T154A and control group cells, which suggested that the observed upregulation of diapedesis in Cx43-expressing cells required heterocellular GJIC. Further study revealed that the gastric cancer cells transmigrated through the intercellular space between the mesothelial cells via a paracellular route. Our results suggest that the abnormal expression of Cx43 plays an essential role in peritoneal metastasis and that Cx43-mediated heterocellular GJIC between gastric cancer cells and mesothelial cells may be an important regulatory step during metastasis. Finally, we observed that the diapedesis of exfoliated gastric cancer cells through mesothelial barriers is a viable route of paracellular migration.

Life cycle assessment (LCA) is used to quantitatively analyze the energy consumption and environmental impact of primary aluminum production in China, the United States, and Europe, as well as global average. The results indicate that electricity and fuel contribute more than 60% of the environmental impact of bauxite mining; steam is the greatest contributor to the environmental impact of alumina production by the Bayer process, with a result exceeding 35%; and electricity contributes >50% of the environmental impact of aluminum electrolysis. The environmental impact of primary aluminum production in China is 1.2 times the global average. The contributions of the three stages of primary aluminum production to the total environmental impact of the process in China are, in descending order, aluminum electrolysis (64.33%), alumina production (33.09%), and bauxite mining (2.58%). If the proportion of thermal power in the electricity source structure is reduced from 60% to 0%, the contribution of electricity to the environmental impact of primary aluminum production will decrease from 38% to 2%, and the total environmental impact will decrease by 73%. Therefore, energy conservation and emissions reduction can be realized through the optimization of the power generation structure, adoption of clean energy production, and improvement of the heat utilization rate in production processes.

Lithium is one of the secondary mineral elements occurring in bauxite. The behavior of lithium-bearing bauxite in the digestion process was investigated, and the effect of digestion conditions on the extraction rates of lithium was studied. The results demonstrate that the mass ratio of the added CaO to bauxite, the KOH concentration, and the digestion temperature had a significant effect on the lithium extraction efficiency. An L9(3⁴) orthogonal experiment demonstrated that the order of each factor for lithium extraction from primary to secondary is lime dosage, caustic concentration, and reaction temperature. Under the optimal conditions (t = 60 min, T = 260 °C, ρ(K₂O) = 280 g/L, and 16% lime dosage), the leaching efficiencies of lithium and alumina are 85.6% and 80.09%, respectively, with about 15% of lithium entering into red mud. The findings of this study maybe useful for controlling lithium content in alumina products and lithium recovery from the Bayer process.