Xinqiang Wu

Direct Mechanism of the First Carbon–Carbon Bond Formation in the Methanol‐to‐Hydrocarbons Process

In the past two decades, the reaction mechanism of C-C bond formation from either methanol or dimethyl ether (DME) in the methanol-to-hydrocarbons (MTH) process has been a highly controversial issue. Described here is the first observation of a surface methyleneoxy analogue, originating from the surface-activated DME, by in situ solid-state NMR spectroscopy, a species crucial to the first C-C bond formation in the MTH process. New insights into the first C-C bond formation were provided, thus suggesting DME/methanol activation and direct C-C bond formation by an interesting synergetic mechanism, involving C-H bond breakage and C-C bond coupling during the initial methanol reaction within the chemical environment of the zeolite catalyst.

Methanol to hydrocarbons reaction over HZSM-22 and SAPO-11: Effect of catalyst acid strength on reaction and deactivation mechanism

The conversion of methanol to hydrocarbons has been investigated over HZSM-22 and SAPO-11. Both of these catalysts possess one-dimensional 10-ring channels, but have different acidic strengths. Comparison studies and C-12/C-13 isotopic switching experiments were conducted to evaluate the influence of the acidic strength of the catalyst on the conversion of methanol, as well as its deactivation mechanism. Although the conversion of methanol proceeded via an alkene methylation-cracking pathway over both catalysts, the acidity of the catalysts had a significant impact on the conversion and product distribution of these reactions. The stability of the catalysts varied with temperature. The catalysts were deactivated at high temperature by the deposition of graphitic coke on their outer surface. Deactivation also occurred at low temperatures a result that the pores of the catalyst were blocked by polyaromatic compounds. The co-reaction of C-13-methanol and C-12-1-butene confirmed the importance of the acidity of the catalyst on the distribution of the hydrocarbon products

Oxidation Behavior of 304 Stainless Steel During Crevice Corrosion in High-Temperature Pure Water

Characteristics of oxide films formed on 304 (UNS S30400) stainless steel during crevice corrosion in 290°C pure water have been investigated. It was found that the oxide films were different at different sites along the crevice. Decreased dissolved oxygen within the crevice resulted in a potential gradient. Such a potential drop affected the development of oxide films. The lamellar oxide near the crevice mouth was mainly FeCr2O4. The regular oxide far from the crevice mouth was mainly Fe3O4. Possible mechanisms of crevice corrosion and growth of the oxide films at different sites in high-temperature water are also discussed.

The anticancer functions of RIG-I–like receptors, RIG-I and MDA5, and their applications in cancer therapy

Cancer is a major cause of death worldwide, and its incidence and mortality continuously increase in China. Nowadays, cancer heavily influences our health and constitutes enormous burden on society and families. Although there are many tools for cancer treatment, but the overall therapeutic effect is poor. In addition, cancer cells often develop resistance to therapy due to defective cell death or immune escape mechanisms. Therefore, it is a promising way for cancer treatment to effectively activate apoptosis and conquer immunosuppression. RIG-I-like receptors (RLRs) belong to RNA-sensing pattern recognition receptors (PRRs), one of the major subsets of PRRs, and play a critical role in sensing RNA viruses and initiate host antiviral responses such as the production of type I interferons (IFNs), proinflammatory cytokines, and other immune response molecules. Recent studies have demonstrated that tumor cells could mimic viral infection to activate viral recognition of immune system and the activation of interferon response pathway. RIG-I and MDA5, two members of RLRs family, could induce growth inhibition or apoptosis of multiple types of cancer cells on the activation by RNA ligands in IFN-dependent or IFN-independent approach. Previous studies have reviewed PRRs as promising immunotherapy targets for colorectal cancer and pancreatic cancer. However, until now, a comprehensive review on the role of RLRs in the development and treatment of various cancers is still lacking. In this article, we reviewed the latest studies on the roles as well as the mechanisms of RIG-I and MDA5 in the development of various cancers and therapeutic potentials of targeting RIG-I and MDA5 for cancer treatment.

Effects of the intestinal microbial metabolite butyrate on the development of colorectal cancer

Colorectal cancer (CRC) is one of the major health threats in developed countries. Changes in dietary components, such as more protein and lipid intake, can increase the risk of CRC. Diet affects CRC in many ways. They regulate the composition and function of gut microbiota, which have an amazing metabolic capacity and can produce short chain fatty acids (SCFAs), such as propionate, acetate, and butyrate. Butyrate is a principal energy source for colonic epithelial cells and plays an important role in maintaining the stability of gut microbiota and the integrity of intestinal epithelium. However, there are few studies reviewing the anti-CRC potentials of butyrate. This review summarizes the recent research progresses in the effect of gut microbiota imbalance and the decrease in intestinal microbial metabolite butyrate caused by unbalanced diet on CRC development, and discusses the mechanisms of butyrate-induced anti-CRC activities, which may guide people to prevent CRC by improving diet structures.