a b s t r a c t2019-nCoV is a newly identified coronavirus with high similarity to SARS-CoV. We performed a structural analysis of the receptor binding domain (RBD) of spike glycoprotein responsible for entry of coronaviruses into host cells. The RBDs from the two viruses share 72% identity in amino acid sequences, and molecular simulation reveals highly similar ternary structures. However, 2019-nCoV has a distinct loop with flexible glycyl residues replacing rigid prolyl residues in SARS-CoV. Molecular modeling revealed that 2019-nCoV RBD has a stronger interaction with angiotensin converting enzyme 2 (ACE2). A unique phenylalanine F486 in the flexible loop likely plays a major role because its penetration into a deep hydrophobic pocket in ACE2. ACE2 is widely expressed with conserved primary structures throughout the animal kingdom from fish, amphibians, reptiles, birds, to mammals. Structural analysis suggests that ACE2 from these animals can potentially bind RBD of 2019-nCoV, making them all possible natural hosts for the virus. 2019-nCoV is thought to be transmitted through respiratory droplets. However, since ACE2 is predominantly expressed in intestines, testis, and kidney, fecal-oral and other routes of transmission are also possible. Finally, antibodies and small molecular inhibitors that can block the interaction of ACE2 with RBD should be developed to combat the virus.

Ultrasonically initiated miniemulsion polymerization of styrene in the presence of Fe3O4 nanoparticles was successfully employed to prepare polystyrene (PS)/Fe3O4 magnetic emulsion and nanocomposite. The effects of Fe3O4 nanoparticles on miniemulsion polymerization process, the structure, morphology and properties of PS/Fe3O4 nanocomposite were investigated. The increase in the amount of Fe3O4 nanoparticles drastically increases the polymerization rate due to that Fe3O4 nanoparticles increase the number of radicals and the cavitation bubbles. Polymerization kinetics of ultrasonically initiated miniemulsion polymerization is similar to that of conventional miniemulsion polymerization. PS/Fe3O4 magnetic emulsion consists of two types of particles: latex particles with Fe3O4 nanoparticles and latex particles with no encapsulated Fe3O4 nanoparticles. Fe3O4 nanoparticles lower the molecular weight of PS and broaden the molecular weight and particle size distribution. Thermal stability of PS/Fe3O4 nanocomposite increases with the increase in Fe3O4 content. PS/Fe3O4 emulsion and nanocomposite exhibit magnetic properties. PS/Fe3O4 magnetic particles can be separated from the magnetic emulsion by an external magnetic field and redispersed into the emulsion with agitation.

Background Several epidemiological studies have investigated the association between whole grains intake and digestive tract cancer risk; however, the results are still controversial. The purpose of this meta-analysis was to assess the association. Methods Studies published before March 2020 were searched in database and other sources. The risk ratio (RR) with the 95% confidence interval (CI) were pooled using fix or random-effects models. Results This meta-analysis included 34 articles reporting 35 studies, 18 studies of colorectal cancer, 11 studies of gastric cancer and 6 studies of esophagus cancer, involving 2,663,278 participants and 28,921 cases. Comparing the highest-intake participants with the lowest-intake participants for whole grains, we found that the intake of whole grains were inversely related to colorectal cancer (RR = 0.89, 95% CI: 0.84–0.93, P < 0.001), gastric cancer (RR = 0.64, 95% CI: 0.53–0.79, P < 0.001), esophagus cancer (RR = 0.54, 95% CI: 0.44–0.67, P < 0.001), respectively. However, subgroup analysis of colorectal cancer found no significant association in the case-control studies and studies of sample size < 500, and subgroup analysis of gastric cancer found no significant association in the cohort studies and studies of American population. No study significantly affected the findings in the sensitivity analysis. No publication bias was found in the studies for colorectal cancer and esophagus cancer except in the studies for gastric cancer. Conclusion This meta-analysis provides further evidence that whole grains intake was associated with a reduced risk of digestive tract cancer. Our result supports the dietary guidelines that increase whole grains intake to reduce the risk of digestive tract cancer.

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