Nitrosamine degradation by UV light in post-combustion CO2 capture: Effect of solvent matrix

AbstractPotential production and emission of nitrosamines during post-combustion CO2 capture has drawn some attention due to their toxicity and potential carcinogenicity. One of the possible ways to reduce the concentration of nitrosamines is irradiation of the liquid streams of the capture plant with UV light. This paper shows experimental results of the degradation of nitrosamines such as N-nitroso-diethanolamine (NDELA) and N-mononitroso-piperazine (MNPZ) in different solvent matrices. These solvent matrices include water and laboratory grade monoethanolamine (MEA) aqueous solutions, as well as aqueous MEA solution and wash water that had been used in a CO2 capture pilot plant connected to a coal-fired power plant. Experiments were conducted in dedicated batch set-ups and in a continuous mini CO2 capture plant. Results show that the UV absorbance of impurities (degradation products and/or dissolved metals) present in MEA solvent that had been used in a pilot plant significantly reduces the UV degradation rate of nitrosamines. Furthermore, UV light seems to accelerate the degradation of the capture solvent itself. For these reasons, if UV light treatment is to be used in full-scale post-combustion CO2 capture plants, suitable locations would be the absorber's washing section or the stripper's condensate. At these locations, less interference of degradation products can occur and there is less solvent to be degraded

Carbon Capture with 4 m Piperazine/4 m 2-Methylpiperazine

AbstractAn equimolar diamine blend of 4 m 2-methylpiperazine (2MPZ) with 4 m piperazine (PZ) is shown to be an attractive solvent for CO2 capture. This blend overcomes the difficulties posed by the narrow solid solubility window of pure 8 m PZ while preserving its benefits. The solid solubility window at 20°C broadens from to . As the blend viscosity is nearly double that of pure PZ, normalizing the capacity by viscosity shows a practical capacity comparable to MEA at 0.63mol CO2/kg solvent. The CO2 absorption rate of the blend is lower, with at 40°C, 84% that of PZ. The heats of CO2 absorption of the blend and PZ are equal at ΔHabs=70kJ/mol. While the blend thermal stability is decreased, Tmax = 155 compared to 163°C, oxidative stability is similar. Lastly, their volatilities are nearly equal with amine Henry's constant near 23Pa at 40°C. In short, the equimolar blend of 4 m 2MPZ with 4 m PZ is a competitive solvent for amine scrubbing

Febrile illness in high-risk children: a prospective, international observational study.

To assess and describe the aetiology and management of febrile illness in children with primary or acquired immunodeficiency at high risk of serious bacterial infection, as seen in emergency departments in tertiary hospitals. Prospective data on demographics, presenting features, investigations, microbiology, management, and outcome of patients within the 'Biomarker Validation in HR patients' database in PERFORM, were analysed. Immunocompromised children (< 18 years old) presented to fifteen European hospitals in nine countries, and one Gambian hospital, with fever or suspected infection and clinical indication for blood investigations. Febrile episodes were assigned clinical phenotypes using the validated PERFORM algorithm. Logistic regression was used to assess the effect size of predictive features of proven/presumed bacterial or viral infection. A total of 599 episodes in 482 children were analysed. Seventy-eight episodes (13.0%) were definite bacterial, 67 episodes probable bacterial (11.2%), and 29 bacterial syndrome (4.8%). Fifty-five were definite viral (9.2%), 49 probable viral (8.2%), and 23 viral syndrome (3.8%). One hundred ninety were unknown bacterial or viral infections (31.7%), and 108 had inflammatory or other non-infectious causes of fever (18.1%). Predictive features of proven/presumed bacterial infection were ill appearance (OR 3.1 (95% CI 2.1-4.6)) and HIV (OR 10.4 (95% CI 2.0-54.4)). Ill appearance reduced the odds of having a proven/presumed viral infection (OR 0.5 (95% CI 0.3-0.9)). A total of 82.1% had new empirical antibiotics started on admission (N = 492); 94.3% proven/presumed bacterial (N = 164), 66.1% proven/presumed viral (N = 84), and 93.2% unknown bacterial or viral infections (N = 177). Mortality was 1.9% (N = 11) and 87.1% made full recovery (N = 522).   Conclusion: The aetiology of febrile illness in immunocompromised children is diverse. In one-third of cases, no cause for the fever will be identified. Justification for standard intravenous antibiotic treatment for every febrile immunocompromised child is debatable, yet effective. Better clinical decision-making tools and new biomarkers are needed for this population. What is Known: • Immunosuppressed children are at high risk for morbidity and mortality of serious bacterial and viral infection, but often present with fever as only clinical symptom. • Current diagnostic measures in this group are not specific to rule out bacterial infection, and positivity rates of microbiological cultures are low. What is New: • Febrile illness and infectious complications remain a significant cause of mortality and morbidity in HR children, yet management is effective. • The aetiology of febrile illness in immunocompromised children is diverse, and development of pathways for early discharge or cessation of intravenous antibiotics is debatable, and requires better clinical decision-making tools and biomarkers

Genomic investigations of unexplained acute hepatitis in children

Since its first identification in Scotland, over 1000 cases of unexplained pediatric hepatitis in children have been reported worldwide, including 278 cases in the UK 1. Here we report investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator subjects, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in liver, blood, plasma or stool from 27/28 cases. We found low levels of Adenovirus (HAdV) and Human Herpesvirus 6B (HHV-6B), in 23/31 and 16/23 respectively of the cases tested. In contrast, AAV2 was infrequently detected at low titre in blood or liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T-cells and B-lineage cells. Proteomic comparison of liver tissue from cases and healthy controls, identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and in severe cases HHV-6B, may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

Genomic investigations of unexplained acute hepatitis in children

Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

Rate Shape Design for Gasoline-Like Fuels at High Injection Pressures Using One-Dimensional Hydraulic Models

Recent research has demonstrated that gasoline compression ignition (GCI) can improve the soot-oxides of nitrogen (NOx) trade-off of conventional diesel engines due to the beneficial properties of light distillate fuels. In addition to air handling and aftertreatment, fuel systems also require further development to realize the potential efficiency and emissions benefits of GCI. Injector one-dimensional (1-D) hydraulic modeling is an important design tool used for this purpose. The current study is a continuation of prior work that used computed physical fuel properties and hydraulic models to accurately simulate high-pressure injection behavior relevant to GCI. With respect to fuel characteristics for the model, physical properties were validated by direct comparison to measurements at temperatures and pressures reaching 150°C and 2500 bar, respectively. Calibration of the injector model discharge coefficients for gasoline-like fuel was automated with various multi-objective optimization approaches coupled to a genetic search algorithm. However, Pareto optimization showed the best closure with an experimental rate of injection (ROI) and total injected quantity compared to other current and previous manual methods. The validated model was then used to determine the injector specifications needed to approach an idealized, slowly opening rate shape that could enable low-NOx combustion. Initial parametric studies of key parameters affecting rate shape showed that changing a combination of nozzle exit, control chamber (or servo) outlet, and needle orifice diameters could produce the desired single injection fueling profile. A transient targeting (TT) optimization technique coupled to a genetic search algorithm was compared to a full-factorial design of experiments (DoE) and showed that both approaches could reasonably achieve the target rate shape. However, TT required a significantly reduced computational runtime. In general, this study provides a robust methodology for accurately simulating gasoline-like fuels in high-pressure injectors and demonstrates a conceptual rate shape targeting process for GCI using 1-D hydraulic models. This tool could potentially be integrated with predictive computational fluid dynamics (CFD) models to achieve a simulation-led combustion system design process that includes rate shaping as an additional avenue for optimization

Inhibitors of Monoethanolamine Oxidation in CO₂ Capture Processes

Aqueous monoethanolamine (MEA) is a good solvent for postcombustion CO₂ capture; however, it is prone to oxidative degradation. The initial test conditions mimicked those found in the absorber of a commercial system: MEA was degraded in the presence of CO₂, with high oxygen mass transfer, and with dissolved metals, at absorber temperatures. In later experiments, high temperature cycling was incorporated into the apparatus to better represent a real system. These cycling results suggest that the unadditized 7 <i>m</i> MEA in a real system contacted with 5% oxygen in the absorber and with the stripper operated at 120 °C would experience close to 5% amine loss per week. Inhibitors such as inhibitor A (Inh A), 2,5-dimercapto-1,3,4-thiadiazole (DMcT), diethylenetriamine pentaacetic acid (DTPA), hydroxyethylidenediphosphonic acid (HEDP), and methyldiethanolamine (MDEA) reduced MEA oxidation at low temperature by more than 90%. Results of the screening study also confirmed the reliability of ammonia production as an accurate indicator of MEA oxidation under all test conditions, allowing for rapid and accurate screening of new additives. Unfortunately, none of the additives screened at low temperature significantly reduced oxidation with high temperature cycling; thus they are not recommended at this point for use in a commercial CO₂ capture system