Experimental and numerical study on explosion resistance of polyurea-coated shelter in petrochemical industry.

To reduce the number of casualties in explosion accidents, blast-resistant shelters can be used to protect personnel in high-risk areas of petrochemical processing plants. In this work, the deformation behaviours of uncoated and polyurea-coated blast-resistant plates were studied through gas explosion tests. An ANSYS/LS-DYNA model of a polyurea-coated shelter was established, and the dynamic responses of the shelter under various explosion loads were analysed. A series of fuel-air explosion tests were carried out to investigate the explosion resistance of the full-scale shelter. The results showed that compared with the uncoated blast-resistant plate, the deformation of the polyurea-coated blast-resistant plate was significantly reduced. The overall deformation of the shelter was the central depression of the wall and the inward bending of the frame. The damage effect of a typical high-overpressure, low-duration load was greater than that of typical low-overpressure, long-duration load. The shelter remained intact under three repeated explosive loads, with cracks appearing on the inner wall but no collapse or debris splashing. The shock wave attenuation rate of the shelter reached over 90%, which could significantly reduce the number of indoor casualties.

Characterization of WO3/Silicone Rubber Composites for Hydrogen-Sensitive Gasochromic Application.

WO3 and silicone rubber (SR)-based gasochromic composites were fabricated to detect hydrogen leaks at room temperature. WO3 rod-like nanostructures were uniformly distributed in the SR matrix, with a particle size of 60-100 nm. The hydrogen permeability of these composites reached 1.77 cm3·cm/cm2·s·cmHg. At a 10% hydrogen concentration, the visible light reflectance of the composite decreased 49% during about 40 s, with a color change rate of 6.4% s-1. Moreover, the composite detected hydrogen concentrations as low as 0.1%. And a color scale was obtained for easily assessing hydrogen concentrations in the environment based on the color of composites. Finally, the composite materials as disposable sensors underwent testing at several Sinopec hydrogen refueling stations.

Remediation of petroleum-contaminated site soil by bioaugmentation with immobilized bacterial pellets stimulated by a controlled-release oxygen composite.

Bioaugmentation techniques still show drawbacks in the cleanup of total petroleum hydrocarbons (TPHs) from petroleum-contaminated site soil. Herein, this study explored high-performance immobilized bacterial pellets (IBPs) embed Microbacterium oxydans with a high degrading capacity, and developed a controlled-release oxygen composite (CROC) that allows the efficient, long-term release of oxygen. Tests with four different microcosm incubations were performed to assess the effects of IBPs and CROC on the removal of TPHs from petroleum-contaminated site soil. The results showed that the addition of IBPs and/or CROC could significantly promote the remediation of TPHs in soil. A CROC only played a significant role in the degradation of TPHs in deep soil. The combined application of IBPs and CROC had the best effect on the remediation of deep soil, and the removal rate of TPHs reached 70%, which was much higher than that of nature attenuation (13.2%) and IBPs (43.0%) or CROC (31.9%) alone. In particular, the CROC could better promote the degradation of heavy distillate hydrocarbons (HFAs) in deep soil, and the degradation rates of HFAs increased from 6.6% to 33.2%-21.0% and 67.9%, respectively. In addition, the IBPs and CROC significantly enhanced the activity of dehydrogenase, catalase, and lipase in soil. Results of the enzyme activity were the same as that of TPH degradation. The combined application of IBPs and CROC not only increased the microbial abundance and diversity of soil, but also significantly enhanced the enrichment of potential TPH-biodegrading bacteria. M. oxydans was dominant in AP (bioaugmentation with addition of IBPs) and APO (bioaugmentation with the addition of IBPs and CROC) microcosms that added IBPs. Overall, the IBPs and CROC developed in this study provide a novel option for the combination of bioaugmentation and biostimulation for remediating organic pollutants in soil.

Bioleaching of metals from spent fluid catalytic cracking catalyst using adapted Acidithiobacillus caldus.

In this study, an adapted bioleaching strain of Acidithiobacillus caldus UVS10 was successfully developed. Batch tests and tests in bioreactor were conducted to evaluate the metals bioleaching performance of A. caldus UVS10 to spent FCC catalyst (SFCCC). Results of batch experiments showed the bioleaching efficiency of Ni, V, La, and Ce in SFCCC reached 19.40%, 22.06%, 53.75%, and 59.56%, respectively. High SFCCC pulp density inhibited the leaching of metals. Sb leaching was inhibited in acidic environment caused by A. caldus UVS10. Contents of Ni, V, La, and Ce in extracellular polymeric substances (EPS) were significantly higher than those intracellular. Accumulation of metal in EPS and cytosol increased with the increase of SFCCC pulp density. V was less intercepted by EPS than Ni, La, and Ce, because of lower toxicity. Experimental results in bioreactor showed that Ni, V, La, and Ce could be effectively leached by A. caldus UVS10 under 10% pulp density. The aeration and stirring operating environment in bioreactor improved the leaching efficiency of metals in SFCCC. After bioleached in bioreactor, the available fraction content of four metals in SFCCC decreased significantly. Ecological risk analysis demonstrated the environmental risks of bioleached SFCCC were significantly lower than raw SFCCC. Different reaction kinetic models were used to represent metals leaching behavior under bioleaching of A. caldus UVS10, leaching of La and Ce showed good agreement with the product layer diffusion model, while Ni and V leaching kinetics fit well with the surface chemical reaction models.

Thermal runaway features of large-format power lithium-ion cells under various thermal abuse patterns and capacities.

Herein, a comprehensive investigation is performed to research the thermal runaway features of large-format power lithium-ion cells under various heating patterns (2 kW electric heating oven and 600 W electric heating plate) and capacities (60, 150, and 180 Ah). Although the electric heating plate induces the cell to encounter thermal runaway earlier in comparison with the electric heating oven, the combustion does not appear for the former case since the compact stacking of the electric heating plate restrains the heat release of the heater such that the surrounding temperature is too low to induce the ignition of the thermal runaway combustibles. Besides that, it is interesting to find that the color of the ejected products under the electric heating plate condition becomes shallower as the thermal runaway proceeds, which implies that the ejecta in the initial of thermal runaway is mixed with quantities of solid particles and the proportion would gradually decrease. With the increase of the cell capacity, thermal runaway emerges later as a result of the greater cell height which delays the cell temperature rise, when exposed to an electric heating oven. In addition, the cell with a larger capacity demonstrates a lower peak temperature, a lower maximum temperature rise rate, a shorter combustion, a lower flame temperature, and a weaker radiation heat strength during thermal runaway; that is, less heat is released due to its violent thermal runaway behaviour. Finally, the severe explosion risk for the larger-capacity cell should be especially noted considering the larger amount of explosive gases released.

Experimental and Numerical Study on Deflagration Characteristics of Large-Scale Propane-Air Mixture.

Seven deflagration tests of a propane-air mixture were carried out in a 22.5 m3 large-scale chamber. The effects of initial volume, gas concentration, and initial turbulence intensity on deflagration characteristics were analyzed. The main frequency of the explosion wave was quantitatively determined by the combination of the wavelet transform and energy spectrum analysis. The results show that the explosive overpressure is formed by the discharge of combustion products and secondary combustion, and the effects of turbulence and gas concentration on the explosive overpressure are higher than the initial volume. Under the condition of weak initial turbulence, the main frequency of gas explosion wave is between 32.13 and 48.33 Hz. Under strong initial turbulence conditions, the main frequency of the gas explosion wave increases with the increase of overpressure, and the empirical formula of the relationship between the main frequency and overpressure is summarized, which could provide theoretical support for the design of mechanical metamaterials for oil and gas explosion. Finally, the flame acceleration simulator numerical model was calibrated through tests, and the overpressure simulation values were in good agreement with the experimental data. The leakage, diffusion, and explosion of a liquefied hydrocarbon loading station in a petrochemical enterprise were simulated. The lethal distance and explosion overpressure at key buildings are predicted for different wind speed conditions. The simulation results can provide a technical basis for evaluating personnel injury and building damage.

Integrative analysis of key microRNA-mRNA complexes and pathways in aortic aneurysm.

Background: This study investigated the therapeutic targets of aortic aneurysm (AA) and provided insights into the pathogenesis and molecular mechanisms of AA. Methods: The messenger RNA (mRNA) datasets, GSE9106 (blood samples) and GSE7084 (tissue samples), and the microRNA (miRNA) datasets, GSE92427 (blood samples) and GSE110527 (tissue samples), were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) and differentially expressed miRNAs (DE-miRNAs) were analyzed by limma. Based on the co-DEGs and co-DE-miRNAs between the AA blood and tissue datasets, the miRNA-mRNA regulatory pairs were predicted. Functional enrichment analyses and gene set enrichment analysis (GSEA) were performed and the protein-protein interaction (PPI) network was generated to further analyze the related genes and their functions. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and tyramide signal amplification (TSA)-in situ hybridization (ISH) assays were performed to detect the expression of co-DE-miRNAs in AA clinical tissue samples and normal aorta samples. Results: There were 19 upregulated and 5 downregulated co-differential mRNAs. MiR-4306 was the upregulated co-differential miRNA, and miR-3198 was the downregulated co-differential miRNA by blood-tissue co-analysis. Based on the co-DEGs and co-DE-miRNAs, 4 miRNA-mRNA regulatory pairs were predicted. PPI networks were constructed of co-DEGs with 6 relationship pairs. RT-qPCR and TSA-ISH assays showed the upregulation of miR-4306 and the downregulation of miR-3198 in AA tissue samples. Conclusions: This study provided evidence regarding the differential regulatory miRNA-mRNA networks in AA blood and tissue samples and identified key genes and signaling pathways related to AA, which provided insights into potential targets and mechanisms of AA pathogenesis and progression.

Prevalence, Clinical Features, and In-hospital Outcome of Fatty Liver Disease in Acute Aortic Dissection: A Single-Center Retrospective Study.

Background and Aims: Fatty liver disease (FLD) has emerged as a major public issue in China. We aim to investigate prevalence, clinical features, and in-hospital outcome of FLD in acute aortic dissection (AAD) patients. Methods: Data of 379 AAD patients from 2017 to 2019 at Renmin hospital of Wuhan University was retrospectively collected and divided according to age and FLD absence. Propensity score matching was used for minimal confounding. We compared their physical environmental parameter of onset, clinical features, and in-hospital outcome. Results: The mean age was 52.0 ± 11.5 years in type A and 55.1 ± 11.4 in type B. 25.0% of type A and 19.2% of type B AAD patients had FLD. Logistic regression indicated a negative association between FLD and age, both in type A [unadjusted odds ratio (OR) 0.958 (per 1 year), 95% confidence interval (CI) 0.930-0.988, p = 0.0064] and type B [unadjusted OR 0.943 (per 1 year), 95% CI 0.910-0.978, p = 0.0013]. After matching, type A with FLD had onset with a lower air quality index (AQI) of 68.5 [interquartile range (IQR) 46.0-90.0] and a lower Pm 2.5 concentration of 36.0 µg/m3 (IQR 23.0-56.0) compared with non-FLD group. In Kaplan-Meier estimation, FLD was associated with higher risk of in-hospital mortality in type B AAD (p = 0.0297). Conclusion: The prevalence of FLD in AAD decrease with age, both in type A and type B AAD. Type A AAD patients with FLD had onset with better air quality parameters compared with non-FLD group. FLD was associated with higher risk of in-hospital mortality in type B AAD.

Elephant Trunk Stent Fenestration for Acute Type A Aortic Dissection.

BACKGROUND: This study investigated the clinical outcomes of elephant trunk stent fenestration in patients with acute type A aortic dissection (ATAAD). METHODS: From January 2009 to December 2019, 271 ATAAD patients were treated in the Department of Cardiovascular Surgery, Renmin Hospital of Wuhan University. Patients underwent deep hypothermia circulatory arrest with bilateral antegrade cerebral perfusion with total arch replacement and elephant trunk stent fenestration. Patient characteristics, perioperative findings, and follow-up results were analyzed retrospectively. RESULTS: The average in-hospital mortality rate was 4.1%, the cardiopulmonary bypass time was 160.8 ± 60.4 minutes, the cross-clamp time was 91.1 ± 24.5 minutes, and the circulatory arrest time was 22.8 ± 5.5 minutes. The rate of reoperation for bleeding was 1.5%, and the pericardial mediastinal drainage volume was 312.0 ± 159.2 mL 24 hours after surgery. Follow-up data were available for 95.4% of patients. Endoleaks developed in 2 patients 3 years after surgery. The postoperative survival rate was 93.0% at 1 year, 89.3% at 5 years, and 81.7% at 10 years. CONCLUSIONS: Elephant trunk stent fenestration can simplify reconstruction of the left subclavian artery in ATAAD patients and reduce surgical difficulty. Because the early postoperative outcomes and long-term results were satisfactory in our sample, this technique should be promoted for some patients with ATAAD.

Painless retrograde type A aortic dissection followed conservative treatment of type B aortic dissection: a case report.

BACKGROUND: Retrograde type A aortic dissection (RTAD) is a fatal aortic disease secondary to descending aortic dissection, and might be misdiagnosed due to its atypical symptoms lead to catastrophic outcomes. CASE PRESENTATION: We herein reported a case of a 40-year old Chinese non-comorbid man who received conservative treatment for acute type B aortic dissection and progressed to RTAD in a painless manner in a week. After open surgical aortic repair with stented elephant truck technique, the patient survived without obvious complication and cured with a satisfactory outcome in a half-year follow-up. CONCLUSION: This case indicates that RTAD may present without typical symptoms, early diagnosis and open surgical procedure are imperative for treating RTAD.

IL-5 overexpression attenuates aortic dissection by reducing inflammation and smooth muscle cell apoptosis.

BACKGROUND: As an inflammation-related cytokine, interleukin (IL)-5 has been reported to be involved in the development of cardiovascular diseases, such as chronic heart failure and atherosclerosis. However, the role of IL-5 in acute aortic dissection (AAD) has barely been explored. METHODS: Aortic tissue samples from normal donors and patients with AAD were collected, and the expression and localization of IL-5 in aortic tissue were analyzed. In addition, a mouse AAD model was established by administering angiotensin II (Ang II) to ß-aminopropionitrile (BAPN)-treated mice. Morphological examinations and histopathologic analyses were performed to evaluate the effects of IL-5 overexpression on the occurrence of AAD. RESULTS: IL-5 expression was significantly decreased in aorta samples from AAD patients compared to those from donors, and macrophages were the main source of IL-5. In addition, IL-5 expression was decreased in plasma and aortic tissue samples from AAD mice. IL-5 overexpression markedly attenuated the occurrence of AAD in mice and produced corresponding decreases in the inflammatory response and cell apoptosis. In cocultures of macrophages and smooth muscle cells (SMCs), IL-5 overexpression in the macrophages significantly reduced Ang II-induced SMC apoptosis. CONCLUSION: IL-5 overexpression suppresses the development of AAD by reducing inflammation and SMC apoptosis. These results suggest that IL-5 is a potential therapeutic target in AAD.

Application of combined physicochemical and biological processes for enhanced treatment of avermectin fermentation wastewater.

This paper aimed at developing the enhanced biological treatment processes for treating avermectin fermentation wastewater (AFW). After UASB treatment and chemical coagulation, the pretreated AFW was subsequently flowed into a rCAA reactor (reactor with repeated coupling of aerobes and anaerobes using macroporous carriers) system for further pollutant degradation and excess sludge reduction. By the treatment with chemical coagulation, COD, total nitrogen and total phosphorus concentration of treated AFW were eliminated to 550-700 mg/L, 130-160 mg/L and 1 mg/L, respectively, and the dark color of the wastewater was greatly bleached. After this decolorized wastewater was treated by the following rCAA bioreactor, the COD could be reduced to around 200-300 mg/L, while the further decrease of COD less than 200 mg/L was difficult. The Biolog analysis and OUR test for the water treated by rCAA bioreactor demonstrated that the effluent from chemical coagulation contained some unknown compounds with low biodegradability and would simplify the microbial community in the subsequent rCAA reactor.

Analysis of the mechanism of sludge ozonation by a combination of biological and chemical approaches.

Using the practical sludge obtained from municipal sewage treatment plants, the mechanism of the sludge ozonation process was systematically investigated by a combination of biological and chemical approaches, including analysis of the changes in biological response by CFU and PCR-DGGE, bio-macromolecular activity and radical scavenging activity. The results indicated that after the sludge was exposed to ozone at less than 0.02 g O(3)/g TSS, the DGGE fingerprint remained constant and there was still some enzyme activity, indicating that the sludge solubilization was the main process. At greater than 0.02 g O(3)/g TSS, the bacteria began to be broken down and ozone was used to oxidize the bio-macromolecules such as proteins and DNA released from the sludge. Bacteria belonging to 'G-Bacteria' were able to conserve their DNA in the presence of less than 0.08 g O(3)/g TSS. At levels higher than 0.10 g O(3)/g TSS, the disintegration of the sludge matrix became slow and the microbes lost most of their activity, and ozone was used to transform the bio-macromolecules into small molecules. However, at levels higher than 0.14 g O(3)/g TSS, the ozone failed to oxidize the sludge efficiently, because several radical scavengers such as lactic acid and SO(4)(2-) were released from the microbial cells in the sludge.

Enhanced coagulation of ferric chloride aided by tannic acid for phosphorus removal from wastewater.

Phosphorus removal from wastewater is of great importance. In the present study, ferric chloride was selected as the coagulant, and tannic acid (TA), a natural polymer, as the coagulant aid to develop an effective coagulation process with the emphasis of phosphorus recovery from different types of wastewater. The results showed that TA can accelerate the settling speed by forming flocs with large size, reduce the residual Fe(III) to eliminate the yellow color caused by Fe(III), and slightly increase the phosphorus removal efficiency. The precipitate formed by TA-aided coagulation showed the advantage of releasing phosphorus faster than ferric phosphate, indicating the possibility of phosphorus recovery from wastewater as slow release fertilizer. To further understand the structural characteristics of the precipitate, analytical techniques such as Raman spectroscopy, X-ray photoelectron spectroscopy and matrix-assisted laser desorption ionization-time of flight mass spectrometry were employed. The analytical results indicated that TA-Fe-P complex was formed during the coagulation/flocculation processes. Solid phase in the precipitate consisted of TA-Fe-P complex, Fe-TA complex and/or ferric hydroxyphosphate.

Enhanced sludge solubilization by microbubble ozonation.

A microbubble ozonation process for enhancing sludge solubilization was proposed and its performance was evaluated in comparison to a conventional ozone bubble contactor. Microbubbles are defined as bubbles with diameters less than several tens of micrometers. Previous studies have demonstrated that microbubbles could accelerate the formation of hydroxyl radicals and hence improve the ozonation of dyestuff wastewater. The results of this study showed that microbubble ozonation was effective in increasing ozone utilization and improving sludge solubilization. For a contact time of 80 min, an ozone utilization efficiency of more than 99% was obtained using the microbubble system, while it gradually decreased from 94% to 72% for the bubble contactor. The rate of microbial inactivation was obviously faster in the microbubble system. At an ozone dose of 0.02g O(3)g(-1) TSS, about 80% of microorganisms were inactivated in the microbubble system, compared with about 50% inactivation for the bubble contactor. Compared to the bubble contactor, more than two times of COD and total nitrogen, and eight times of total phosphorus content were released from the sludge into the supernatant by using the microbubble system at the same ozone dosage. The application of microbubble technology in ozonation processes may provide an effective and low cost approach for sludge reduction.

Enhanced ozonation of simulated dyestuff wastewater by microbubbles.

The ozonation of synthetic wastewater containing azo dye, CI Reactive Black 5, was investigated using a microbubble generator and a conventional bubble contactor. The microbubble generator produced a milky and high intensity microbubble solution in which the bubbles had a mean diameter of less than 58 microm and a numerical density of more than 2.9 x 10(4) counts ml(-1) at a gas flow rate of less than 0.5 l min(-1). Compared with the bubble contactor, the total mass transfer coefficient was 1.8 times higher and the pseudo-first order rate constant was 3.2-3.6 times higher at the same initial dye concentration of 100 mg l(-1), 230 mg l(-1) and 530 mg l(-1) in the proposed microbubble system. The amount of total organic carbon removed per g of ozone consumed was about 1.3 times higher in the microbubble system than in the bubble contactor. The test using terephthalic acid as the chemical probe implied that more hydroxyl radicals were produced in the microbubble system, which contributed to the degradation of the dye molecules. The results suggested that in addition to the enhancement of mass transfer, microbubbles, which had higher inner pressure, could accelerate the formation of hydroxyl radicals and hence improve the oxidation of dye molecules.

Biological wastewater treatment by a bioreactor with repeated coupling of aerobes and anaerobes aiming at on-site reduction of excess sludge.

Activated sludge has been widely used in wastewater treatment throughout the world. However, the biggest disadvantage of this method is the by-production of excess sludge in a large amount, resulting in difficulties in operation and high costs for wastewater treatment. Technological innovations for wastewater treatment capable of reducing excess sludge have thus become research topics of interest in recent years. In our present research, we developed a new biological wastewater treatment process by repeated coupling of aerobes and anaerobes (rCAA) to reduce the excess sludge during the treatment of wastewater. During 460-day continuous running, COD (300-700 mg/L) and TOC (100-350 mg/L) were effectively removed, of which the removal rate was above 80 and 90%, respectively. SS in the effluent was 13 mg/L on average in the rCAA bioreactor without a settling tank. The on-site reduction of the excess sludge in the rCAA might be contributed by several mechanisms. The degradation of the grown aerobes after moving into the anaerobic regions was considered to be one of the most important factors. Besides, the repeatedly coupling of aerobes and anaerobes could also result in a complex microbial community with more metazoans and decoupling of the microbial anabolism and catabolism.