Chemical-looping with oxygen uncoupling (CLOU) is a developing technology, which allows for inherent separation of carbon dioxide during combustion of gaseous and solid fuels. In contrast to the related chemical-looping combustion technology (CLC), where gaseous or gasified fuels react directly with oxygen carrier materials, CLOU utilizes oxygen carriers capable of releasing gaseous oxygen, provided appropriate thermal conditions exist in the fuel reactor, whereupon fuel reacts with the released oxygen. The oxygen carriers are thereafter regenerated by oxidation in the air reactor. In this work, a set of oxygen carrier materials synthesized from manganese oxides mixed with iron, nickel, and silicon oxides are evaluated in terms of their ability to release oxygen and to be regenerated with oxygen and in terms of demonstrated methane conversion in a quartz fluidized bed batch reactor at 810, 850, and 900 °C. The results demonstrate that two Mn/Fe oxygen carriers and one Mn/Ni oxygen carrier have both oxygen release characteristics and high reactivities with methane. The Mn/Fe oxygen carrier synthesized at 1100 °C was additionally shown to have an increasing methane conversion on a long-term basis, which opens for a possibility to use Mn/Fe oxygen carriers in time-extended large-scale chemical-looping operations.

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BackgroundObesity is a major public health problem leading to co-morbidities such as diabetes, hypertension and kidney failure. Bariatric surgery results in pronounced and maintained weight loss and prevention of obesity-related diseases and their complications. Most studies of bariatric surgery on kidney disease show improvements after surgery. However, long-term studies analyzing hard end-points are lacking. Here we report on the long-term effects of bariatric surgery compared to usual obesity care on incidence of end-stage renal disease (ESRD) alone and in combination with chronic kidney disease stage 4 (CKD4/ESRD).Methods4047 patients were included in the Swedish Obese Subjects (SOS) study. Inclusion criteria were age 37–60 years and BMI≥34 in men and BMI≥38 in women. Patients in the bariatric surgery group (N=2010) underwent banding (18%), vertical banded gastroplasty (69%) or gastric bypass (13%); controls (N=2037) received usual obesity care. In this analysis, patients were followed up for a median time of 18 years. The incidence of ESRD and CKD4 was obtained by crosschecking the SOS database with the Swedish National Patient Register.ResultsDuring follow-up, ESRD occurred in 13 patients in the surgery group and in 26 patients in the control group (adjusted hazard ratio (HR) = 0.27; 95% CI 0.12 – 0.60; p=0.001). The number of CKD4/ESRD events was 23 in the surgery group and 39 in the control group (adjusted HR = 0.33; 95% CI 0.18 – 0.62; p<0.001). In both analyses, bariatric surgery had a more favorable effect in patients with baseline serum insulin levels above median compared to those with lower insulin levels (interaction p=0.010). Treatment benefit of bariatric surgery was also greater in patients with macroalbuminuria at baseline compared to those without macroalbuminuria (interaction p<0.001).ConclusionsOur study showed for the first time that bariatric surgery is associated with a long-term protection against ESRD and CKD4/ESRD.

Chemical-looping combustion (CLC) is a promising technology for CO 2 capture in the process of combustion of gaseous fossil fuels. Oxygen carrier materials based on Ni/NiO on NiAl 2 O 4 and on NiAl 2 O 4 /MgAl 2 O 4 support have previously shown high initial activity combined with high conversion of methane and low concentration of outgoing CO. The feasibility of the Ni/NiO system for CLC depends largely on the lifetime of the oxygen carrier particles in the reactor due to the high price of the material. Avoiding chemical and physical degradation of oxygen carriers is essential for long-term industrial-scale chemical-looping combustion operations, and the particles' activity and mechanical durability have to remain high during long operation times. In this study, a series of oxygen carrier samples were collected from a 10 kW CLC combustor operated for a total of 1016 h using oxygen carrier materials based on NiO/NiAl 2 O 4 (N-VITO) for 405 h and a mixture of used NiO/NiAl 2 O 4 with fresh NiO/NiAl 2 O 4 /MgAl 2 O 4 (N-VITOMg) for 611 h, respectively. These samples were collected after certain time intervals and analyzed in terms of reactivity with methane in a quartz batch reactor. Also, the structural and mechanical properties of these samples were investigated by means of powder XRD, BET surface area measurements, light and scanning electron microscopy, energy dispersive X-ray spectrometry, and crushing strength evaluation. It was shown that both N-VITO and N-VITO/N-VITOMg demonstrate high reactivity and mechanical durability after having been used for more than 1000 h in the CLC 10 kW reactor, which makes them excellent candidates for applications within the area of chemical-looping combustion.

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