Investigation of the Multi-Scale Deterioration Mechanisms of Anhydrite Rock Exposed to Freeze-Thaw Environment.

The deterioration of anhydrite rock exposed to a freeze-thaw environment is a complex process. Therefore, this paper systematically investigated the physical and mechanical evolutions of freeze-thawed anhydrite rock through a series of multi-scale laboratory tests. Meanwhile, the correlation between pore structure and macroscopic mechanical parameters was discussed, and the deterioration mechanisms of anhydrite rock under freeze-thaw cycles were revealed. The results show that with the increase in freeze-thaw processes, the mechanical strength, elastic modulus, cohesion, proportions of micropores (r ≤ 0.1 µm), and PT-Ipore throat (0-0.1 µm) decrease exponentially. In comparison, the mass variation, proportions of mesopores (0.1 µm < r < 1 µm), macropores (r ≥ 1 µm), and PT-II pore throat (0.1-4 µm) increase exponentially. After 120 cycles, the mean porosity increases by 66.27%, and there is a significant honeycomb and pitted surface phenomenon. Meanwhile, as the freeze-thaw cycles increase, the frost resistance coefficient decreases, while the damage variable increases. The correlation analysis between pore structure and macroscopic mechanical parameters shows that macropores play the most significant role in the mechanical characteristic deterioration of freeze-thawed anhydrite rock. Finally, it is revealed that the water-rock expansion and water dissolution effects play a crucial role in the multi-scale damage of anhydrite rock under the freeze-thaw environment.

Development, dilemma and potential strategies for the application of nanocatalysts in wastewater catalytic ozonation: A review.

With the continuous development of nanomaterials in recent years, the application of nanocatalysts in catalytic ozone oxidation has attracted more and more researchers' attention due to their excellent catalytic properties. In this review, we systematically summarized the current research status of nanocatalysts mainly involving material categories, mechanisms and catalytic efficiency. Based on summary and analysis, we found most of the reported nanocatalysts were in the stage of laboratory research, which was caused by the nanocatalysts defects such as easy aggregation, difficult separation, and easy leakage. These defects might result in severe resource waste, economic loss and potentially adverse effects imposed on the ecosystem and human health. Aiming at solving these defects, we further analyzed the reasons and the existing reports, and revealed that coupling nano-catalyst and membrane, supported nanocatalysts and magnetic nanocatalysts had promising potential in solving these problems and promoting the actual application of nanocatalysts in wastewater treatment. Furthermore, the advantages, shortages and our perspectives of these methods are summarized and discussed.

Effect of extrusion-spheronization granulation and manganese loading on catalytic ozonation of petrochemical wastewater.

The petrochemical secondary effluent (PSE) is typical refractory wastewater derived from the petrochemical industries, which requires advanced treatment due to the strict environmental protection policies. Catalytic ozonation is one of the most widely used advanced oxidation technologies in wastewater treatment because of its high mineralization rate, in which the alumina-based catalyst usually plays an important role. Extrusion-spheronization is a promising technique for the preparation of alumina spheres because the synthesized alumina particles have high sphericity, high specific surface aera and narrow particle size distribution. In this paper, two kinds of alumina-based catalysts (catalyst A: manganese nitrate added after alumina granulation and catalyst B: manganese nitrate added into alumina powder before granulation) were prepared by the extrusion-spheronization method and used for PSE treatment by catalytic ozonation. The prepared alumina samples were characterized by Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM), while the wastewater samples were analyzed for Total organic carbon (TOC), UV254 and fluorescence spectroscopy. Results showed that manganese was uniformly distributed in both catalysts, and the specific surface area of two catalysts was 318.36 m2/g and 354.95 m2/g, respectively. Catalytic ozonation experiments were repeated nine times with each catalyst under the same conditions. The TOC removal rates for catalysts A and B in the first run were 48.88% and 49.06%, respectively, then it dropped to 28.05% for catalyst A but remained 47.81% for catalyst B after using for nine times. This implied that the long-term performance of catalyst B would be more stable than catalyst A. Similar result were found in three-dimensional fluorescence analysis. UV254 results indicated that the removal efficiency of aromatic and unsaturated substances by catalyst B was higher than catalyst A. A possible explanation is that the active component manganese oxide formed a catalyst skeleton in catalyst B, which makes it hard to dissolve. Effect of extrusion-spheronization granulation and manganese loading on advanced oxidant treatment of petrochemical wastewater.

A thorough observation of an ozonation catalyst under long-term practical operation: Deactivation mechanism and regeneration.

Heterogeneous catalytic oxidation, as an efficient advanced treatment technology, has been gradually applied in industrial wastewater treatment. The fixed bed technique is one of the most popular catalytic ozonation methods. However, few studies have concentrated on the long-term operation effects on catalysts. In this study, we conducted long-term (~5 years) observations of the operation of the largest petrochemical wastewater treatment plant (treatment capacity 120,000 m3/d) with catalytic ozonation technology in China. A commercial catalyst, which uses Al2O3 pellets supporting copper oxide was applied in this plant. The results showed that the catalytic efficiency gradually decreased from 60.65% to 25.98% since 2018, and the ozone dosage to COD removal ratio (ozone/COD) also increased from 0.82 to 1.93 mg/mg as the running time continued. By means of the comparison and characterization of fresh catalyst and used catalyst, a "mucus layer" was formed by the adsorption of negatively charged extracellular polymeric substances on the positively charged catalyst surface and the interception of the catalyst layer. The mucus layer significantly reduced the catalytic efficiency by isolating ozone with catalytic active sites and releasing extra organic contaminants during the catalytic process resulting in 53.97% TOC increase in the batch test. Meanwhile, regeneration experiments revealed that the TOC removal efficiency was 4.76% and 43.48% in presence of washed catalysts and calcinated catalysts, respectively. Compared with the fresh catalyst, 73% of the catalytic activity was recovered for calcinated catalyst. Consequently, this study provides much practical information, showing positive effects on the promotion of catalytic ozonation application in actual wastewater treatment.

Iron foam coupled hydrolysis acidification for trichloroacetaldehyde treatment: Strengthening characteristics and mechanism.

This research studied transformative characteristics and enhanced mechanism of trichloroacetaldehyde (TCAL), one of chlorinated acetaldehydes (CAAs), by coupled-type iron foam enhanced hydrolysis acidification (HA) reactor. Main results were given that better dechlorination and aldehyde removal were achieved at this process than coupled-type iron foam enhanced HA, alone iron foam and HA reactor. The reasons were due to better strengthening effects of iron foam and HA, iron foam reduced TCAL toxicity to microbes caused an improvement of microbial activity, therefore, volatile fatty acids (VFAs) content and acetate acid (Ac) ratio were increased compared with HA. Moreover, it promoted the enrichment of Actinobacteriota and Firmicutes, and more extracellular polymeric substance (EPS) and enzymes enhanced dechlorination and aldehyde removal. Certainly, microbes reduced iron foam passivation and facilitated its oxidation further improved the strengthening effect.

The Mechanical Properties of Early Aged Shotcrete under Internal Sulfate Attack.

Shotcrete is the primary material for tunnel support due to its early rapid hardening characteristics. During tunnel construction in a sulfate environment, the hardening law of concrete will be affected. In this study, samples were prepared at six different curing times and immersed in four different concentrations of sulfate solutions. A uniaxial test was conducted and analyzed to investigate the effect of sulfate attack on the mechanical properties of early aged shotcrete materials. Results indicated that waterlogged shotcrete does not have apparent cracks on the outside. The stress-strain curve or ultimate compressive strength of the samples showed that the effect of sulfate on shotcrete should be differentiated into chemical and physical sulfate attacks, according to the concentration of sulfate ions. The two parameters in the equation of the hardening behaviors of sulfate attack samples, ultimate compressive strength, and time constant, are related to sulfate concentration. The crack damage stress threshold of samples demonstrates that high-concentration sulfate corrosion leads to an impact on the durability of shotcrete.

A magnetic-void-porous MnFe2O4/carbon microspheres nano-catalyst for catalytic ozonation: Preparation, performance and mechanism.

Wastewater treatment is essential to guarantee human health and ecological security. Catalytic ozonation with nanocatalysts is a widely studied and efficient treatment technology. However, this method has always been limited by nanocatalysts disadvantages such as easily loss, difficult to separate and reuse, and catalytic ability decay caused by aggregation, which could cause severe resources waste and potential risk to human health and ecosystem. To remedy these challenges, a magnetic-void-porous MnFe2O4/carbon microsphere shell nanocatalyst (CMS-MnFe2O4) was successfully synthesized using renewable natural microalgae. The separation test showed CMS-MnFe2O4 was rapidly separated within 2 min under an external magnetic field. In catalytic ozonation of oxalic acid (OA), CMS-MnFe2O4 showed efficient and stable catalytic efficiency, reaching a maximum total organic carbon removal efficiency of 96.59 % and maintained a 93.88 % efficiency after 4 cycles. The stable catalytic efficiency was due to the supporting effects of the carbon microsphere shell, which significantly enhanced CMS-MnFe2O4 chemical stability and reduced the metal ions leaching to 10-20 % of MnFe2O4 through electron transfer. To explore the catalytic mechanism, radical experiments were conducted and a new degradation pathway of OA involving superoxide anions rather than hydroxyl radicals was proposed. Consequently, this study suggests that an efficient, recyclable, stable, and durable catalyst for catalytic ozonation could be prepared.

Amphoteric starch-based bicomponent modified soil for mitigation of harmful algal blooms (HABs) with broad salinity tolerance: Flocculation, algal regrowth, and ecological safety.

The treatment of harmful algal blooms (HABs) by in-situ flocculation is an emerging technology capable of efficiently removing HABs from natural waters. However, differences in salinity, pH and algal species in freshwaters and seawaters can influence the flocculation treatment. In this study, we developed a bicomponent modified soil using amphoteric starch (AS) and poly-aluminium chloride (PAC) in order to effectively flocculate microalgae under broad salinity conditions. Specifically, the impacts of water salinity (0-3.3%), pH (3-11), and algal species (Microcystis aeruginosa and marine Chlorella sp.) were investigated in order to evaluate efficiency, dosage and mechanisms of algae flocculation. The results showed that AS-PAC modified soils possessed excellent resistance to salinity change due to the anti-polyelectrolyte effect of AS, which contributed to 99.9% removal efficiency of M. aeruginosa in fresh and saline waters, and Chlorella sp. in marine water, respectively. The dosage of the flocculant modifier was only 10-20% of that of another proven modifier (i.e. Moringa oleifera), which substantially reduced the material cost. The high salinity tolerance of algal flocculation by the AS-PAC modified soil was attributed to the synergistic processes of charge neutralization and netting-bridging. Thus, this study has developed a universal flocculant and revealed fundamental mechanisms for the mitigation of HABs under broad salinity conditions.

Studies on effects of traffic tunnels on the migration of the contaminants under landfill sites.

Three landfills are located in the eastern part of the Chengdu City, and two traffic tunnels pass beneath the south portion of landfill-1. The landfills have a simple leachate collection system without any bottom liner and impermeable wall, which causes a severe corrosion of the traffic tunnels from 175 to 250 m in the test section. In order to explore how the traffic tunnels impact the transport path of contaminants infiltrating from landfills, a groundwater flow model and a solute transport model were established in the present study. It was found that, after 16 years of operation, the traffic tunnels will accelerate the vertical migration of sulfate ions in the area between the tunnels. Furthermore, 64 water samples along the traffic tunnels were collected to test the concentration of the contaminants. According to the distribution mechanism of the measured concentrations in the traffic tunnels, a preliminary treatment plan was proposed to control the further corrosion of the tunnels and the spread of the contaminants.

IL-27 and IL-27-producing CD4+ T cells in human tuberculous pleural effusion.

The objective of the present study was to figure out whether human IL-27-producing CD4(+) T cells represent a distinct T cell subset in tuberculosis pleural effusion (TPE). Distribution, phenotypic features of IL-27-producing CD4(+) T cells in TPE were determined. The required transcription factors and signal transductions for IL-27-producing CD4(+) T cell differentiation were explored. The immune regulation of IL-27 on pleural mesothelial cells was observed. We have determined the presence of a subset of human Th cells that infiltrated into tuberculous pleural effusion, which was characterized by the secretion of IL-27, and somehow IFN-γ, but not of IL-4, IL-9, IL-17, or IL-22. These IL-27-producing CD4(+) T cells were effector memory cells and exhibited a transcription profile clearly separated from those of Th2, Th17, Th9, and Th22 cells. The in vitro experiments showed that IL-1ß, IL-2 and IL-12, or their various combinations could promote IL-27(+)CD4(+) T cell differentiation from naive CD4(+) T cells by means of phosphorylation of STAT3, STAT4, or/and STAT5. Transcription factors c-Fos and T-bet were required for IL-27(+)CD4(+) T cell differentiation. By activating STAT3 signaling, IL-27 not only restored a clear epithelial phenotype of pleural mesothelial cells, but also further reversed IFN-γ-induced epithelial-mesenchymal transition of pleural mesothelial cells. These data suggested that human IL-27(+)CD4(+) T cells might represent a distinct human T cell subset with unique expression profiles of transcription factors and proinflammatory cytokines, and these IL-27(+)CD4(+) T cells may play important roles in tuberculosis immunity by affecting pleural mesothelial cells.

Rapamycin attenuates bleomycin-induced pulmonary fibrosis in rats and the expression of metalloproteinase-9 and tissue inhibitors of metalloproteinase-1 in lung tissue.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is the most common and devastating form of interstitial lung disease (ILD) in the clinic. There is no effective therapy except for lung transplantation. Rapamycin is an immunosuppressive drug with potent antifibrotic activity. The purpose of this study was to examine the effects of rapamycin on bleomycin-induced pulmonary fibrosis in rats and the relation to the expression of metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1). METHODS: Sprague-Dawley rats were treated with intratracheal injection of 0.3 ml of bleomycin (5 mg/kg) in sterile 0.9% saline to make the pulmonary fibrosis model. Rapamycin was given at a dose of 0.5 mg/kg per gavage, beginning one day before bleomycin instillation and once daily until animal sacrifice. Ten rats in each group were sacrificed at 3, 7, 14, 28 and 56 days after bleomycin administration. Alveolitis and pulmonary fibrosis were semi-quantitatively assessed after HE staining and Masson staining under an Olympus BX40 microscope with an IDA-2000 Image Analysis System. Type I and III collagen fibers were identified by Picro-sirius-polarization. Hydroxyproline content in lung tissue was quantified by a colorimetric-based spectrophotometric assay, MMP-9 and TIMP-1 were detected by immunohistochemistry and by realtime quantitative reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Bleomycin induced alveolitis and pulmonary fibrosis of rats was inhibited by rapamycin. Significant inhibition of alveolitis and hydroxyproline product were demonstrated when daily administration of rapamycin lasted for at least 14 days. The inhibitory efficacy on pulmonary fibrosis was unremarkable until rapamycin treatment lasted for at least 28 days (P < 0.05). It was also demonstrated that rapamycin treatment reduced the expression of MMP-9 and TIMP-1 in lung tissue that was increased by bleomycin. CONCLUSION: These results highlight the significance of rapamycin in alleviating alveolitis and pulmonary fibrosis, which is associated with decreased expression of MMP-9 and TIMP-1.

Diagnostic values of soluble mesothelin-related peptides for malignant pleural mesothelioma: updated meta-analysis.

OBJECTIVE: Although the values of soluble mesothelin-related peptides (SMRPs), including mesothelin and megakaryocyte potentiating factor, in serum and/or pleural fluid for diagnosing malignant pleural mesothelioma (MPM) have been extensively studied, the exact diagnostic accuracy of these SMRPs remains controversial. The purpose of the present meta-analysis is to update the overall diagnostic accuracy of SMRPs in serum and, furthermore, to establish diagnostic accuracy of SMRPs in pleural fluid for MPM. DESIGN: Systematic review and meta-analysis. METHODS: A total of 30 articles of diagnostic studies were included in the current meta-analysis. Sensitivity, specificity and other measures of accuracy of SMRPs in serum and pleural fluid for the diagnosis of MPM were pooled using random effects models. Summary receiver operating characteristic curves were used to summarise overall test performance. RESULTS: The summary estimates of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic OR were 0.61, 0.87, 5.71, 0.43 and 14.43, respectively, for serum and 0.79, 0.85, 4.78, 0.30 and 19.50, respectively, for pleural fluid. It was also found that megakaryocyte potentiating factor in serum had a superior diagnostic accuracy compared with mesothelin for MPM. CONCLUSIONS: SMRPs in both serum and pleural fluid are helpful markers for diagnosing MPM with similar diagnostic accuracy. The negative results of SMRP determinations are not sufficient to exclude non-MPM, and the positive test results indicate that further invasive diagnostic steps might be necessary for the diagnosis of MPM.

Interplay of Th1 and Th17 cells in murine models of malignant pleural effusion.

RATIONALE: IFN-γ-producing CD4(+) T (Th1) cells and IL-17-producing CD4(+) T (Th17) cells have been found to be involved in multiple malignancies; however, the reciprocal relationship between Th1 and Th17 cells in malignant pleural effusion (MPE) remains to be elucidated. OBJECTIVES: To explore the differentiation and immune regulation of Th1 and Th17 cells in the development of MPE in murine models. METHODS: The distribution and differentiation of Th1 and Th17 cells in MPE were investigated in IFN-γ(-/-), IL-17(-/-), and wild-type mice. The effects of Th1 and Th17 cells on the development of MPE and the survival of mice bearing MPE were also investigated. MEASUREMENTS AND MAIN RESULTS: We have demonstrated that increased Th1 and Th17 cells could be found in MPE as compared with blood and spleen. Compared with wild-type mice, Th17 cells were markedly augmented in MPE from IFN-γ(-/-) mice, and improved survival could be seen in IFN-γ(-/-) mice. Th1 cell numbers were elevated in MPE from IL-17(-/-) mice, and decreased survival could be seen in IL-17(-/-) mice. The in vitro experiments showed that IFN-γ deficiency promoted Th17-cell differentiation by suppressing the STAT3 pathway and that IL-17 deficiency promoted Th1-cell differentiation by suppressing the STAT1 pathway. CONCLUSIONS: In mouse models of MPE, IFN-γ inhibited Th17-cell differentiation, whereas IL-17 inhibited Th1-cell differentiation. IL-17 inhibited the formation of MPE and improved the survival of mice bearing MPE; in contrast, IFN-γ promoted MPE formation and mouse death.

Regulation of CD4(+) T cells by pleural mesothelial cells via adhesion molecule-dependent mechanisms in tuberculous pleurisy.

BACKGROUND: Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) have been demonstrated to be expressed on pleural mesothelial cells (PMCs), and to mediate leukocyte adhesion and migration; however, little is known about whether adhesion molecule-dependent mechanisms are involved in the regulation of CD4(+) T cells by PMCs in tuberculous pleural effusion (TPE). METHODS: Expressions of ICAM-1 and VCAM-1 on PMCs, as well as expressions of CD11a and CD29, the counter-receptors for ICAM-1 and VCAM-1, respectively, expressed on CD4(+) T cells in TPE were determined using flow cytometry. The immune regulations on adhesion, proliferation, activation, selective expansion of CD4(+) helper T cell subgroups exerted by PMCs via adhesion molecule-dependent mechanisms were explored. RESULTS: Percentages of ICAM-1-positive and VCAM-1‒positive PMCs in TPE were increased compared with PMC line. Interferon-γ enhanced fluorescence intensity of ICAM-1, while IL-4 promoted VCAM-1 expression on PMCs. Percentages of CD11a(high)CD4(+) and CD29(high)CD4(+) T cells in TPE significantly increased as compared with peripheral blood. Prestimulation of PMCs with anti‒ICAM-1 or ‒VCAM-1 mAb significantly inhibited adhesion, activation, as well as effector regulatory T cell expansion induced by PMCs. CONCLUSIONS: Our current data showed that adhesion molecule pathways on PMCs regulated adhesion and activation of CD4(+) T cells, and selectively promoted the expansion of effector regulatory T cells.