Search

To clarify the influence of H2O thermal effect on the formation of ultrafine particulate matter (PM), Huangling coal char was burned in a high-temperature drop tube furnace at 1800 K under various O2/N2/H2O and O2/N2/H2O/Ar atmospheres. The introduction of Ar in the simulating atmosphere was designed to counteract the thermal effect of H2O. Results indicated that after eliminating the thermal effect of H2O, the yield of ultrafine PM continuously increased in higher H2O content. Compared with no H2O, the mass and number yield of ultrafine PM in O2/N2/H2O/Ar atmosphere with 30% H2O content increased by 35.5% and 58.9%, respectively. H2O thermal effect, gasification reaction, and char oxidation reaction during coal char combustion played a significant role in the formation of ultrafine PM. Oxidation reaction was the primary factor affecting the formation of ultrafine PM, and its relative contribution was more than 62.9%, whereas the thermal effect of H2O showed an overall negative net effect on the formation of ultrafine PM. With the H2O content varied from 5% to 30%, the contribution of H2O thermal effect to mass yield was in the range of −19.1% to −18.0%, while that to number yield was −33.1% to −30.6%. Once the H2O content reached 10%, the enhancing effect of H2O gasification reaction on the yield of ultrafine PM surpassed the negative contribution of H2O thermal effect. For a given H2O content, elevated O2 concentration weakened the negative contribution of H2O thermal effect. [ABSTRACT FROM AUTHOR]

Introduction. The association between Helicobacter pylori (H. pylori) infection and depression and anxiety has been reported in the literature. The aim of this meta‐analysis is to investigate the association of H. pylori infection with depression and anxiety. Methods. A systematic search was conducted in PubMed, Web of Science, Embase, and Chinese databases for observational studies that reported the incidence or prevalence of depression and anxiety in patients with H. pylori infection. We conducted meta‐analysis with a random‐effects model. Results. A total of twelve studies were included in this meta‐analysis. Significant and positive association was found for H. pylori infection with anxiety (OR 2.49, 95% CI 1.83–3.39), but not depression (OR 1.40, 95% CI 0.75–2.58). Subgroup analysis from study design noted a significant positive association between H. pylori infection and anxiety (case‐control and cross‐sectional study, OR 2.36, 95% CI 1.65–3.38; cohort study, RR 1.72, 95% CI 1.28–2.32). The similar trend among studies used the Self‐Rating Anxiety Scale (OR 2.43, 95% CI 1.78–3.32) and other questionnaires (OR 2.41, 95% CI 1.50–3.87) have been observed. However, subgroup analysis of the association between H. pylori infection and depression yields different results. Subgroup analysis from cohort studies noted a significant association between H. pylori infection and depression (RR 1.99, 95% CI 1.33–2.99), but not case‐control and cross‐sectional studies (OR 1.20, 95% CI 0.59–2.46). A significant positive association has been observed among studies used the Self‐Rating Depression Scale (OR 2.03, 95% CI 1.11–3.70), as opposed to studies using other questionnaires (OR 1.03, 95% CI 0.31–3.44). Conclusion. This meta‐analysis provide the support that a significant positive association between H. pylori infection and anxiety disorders. However, the association between H. pylori infection and depression appears to be insignificant. [ABSTRACT FROM AUTHOR]

Stable flow and discharge of the slag in an entrained flow gasifier are the key factors to ensure the long-term stable operation of gasifier. In this work, the melting and flow behavior of coal ash with different Fe2O3/SiO2 ratios was studied in a reduced atmosphere. The results show that the viscosity of slag decreases significantly with the increase of Fe2O3/SiO2. And the critical viscosity-temperature (TCV) decreases from 1309°C to 1226°C. It is found that more than 90% of iron ions exist in the form of Fe2+ in liquid slag by chemical titration. There are more simple ion clusters with low bridge oxygen number (BO) with the increase of Fe2+ and lead to depolymerization of slag. Furthermore, the ash with high SiO2 content can be transformed into slag with high viscosity at a low melting rate by the analysis of the slag area curve and X-ray diffraction pattern, which is considered to be controlled by the "softening-melting" mechanism. The ash with high Fe2O3/SiO2 can be transformed rapidly into a low viscosity liquid at a short melting interval, which follows the "melting-dissolution" mechanism. And it is helpful to promote the formation of low-temperature eutectics with the increase in Fe2O3/SiO2 by thermodynamic calculation. Research on the melting mechanism of slag will provide theoretical support for the regulation of slag flow characteristics. [ABSTRACT FROM AUTHOR]