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Olivine and alkali-feldspar were utilized in separate campaigns in an indirect dual fluidized bed gasification campaign with woody biomass as fuel. After three days, both bed materials were reported to be active towards tar removal and exhibited oxygen-carrying abilities and had formed an ash layer consisting of an outer ash deposition layer and an inner interaction layer. X-ray microtomography analysis concluded that a preferred deposition of ash happens onto convex regions of the bed particles, which results in an increase in thickness of the ash layer over convex regions. This effect is most pronounced for the outer layer which is a product of ash deposition. The inner layer exhibits a homogeneous thickness and is probably formed by interaction of Ca from the outer layer with the particles. Transmission electron microscopy revealed the presence of Fe and Mn on the surface of the particles in a solid solution with Mg. The oxygen-carrying effect which is found for aged particles is therefore attributed to the presence of Fe and Mn on the surface of aged particles. Alkali were found on the surface of both particles which are likely contributing to the catalytic activity of the material towards tar removal. Validerad;2022;Nivå 2;2022-11-02 (sofila);This article has previously appeared as a manuscript in a thesis

Thermal conversion of automotive shredder residue (ASR) using indirect fluidized bed gasification was conducted in the Chalmers semi-industrial 2-4-MWth gasifier. The bed material consisted of olivine that was activated through the deposition of biomass ash prior to a 13-day exposure to ASR. The interactions between the bed material and the ASR ash were investigated using XRD, SEM-EDS, and thermodynamic modeling. The deposition of iron (Fe) onto the olivine particles was noted, and this is likely to increase the oxygen-carrying ability of the particles. Furthermore, at the end of the campaign, about one-third of the particles in the bed were found to originate from the ASR ash. These particles were rich in Fe and Si, as well as elements found exclusively in the ASR ash, such as Zn, Ti, and Cu. Some of these particles exhibited a hollow morphology, suggesting a melt state during their formation in the gasifier. In addition, a low level of agglomeration of the ash and olivine particles was detected. Thermodynamic modeling with the FactSage software indicated the formation of slag. This study presents a detailed investigation of the interactions that occur between the bed material and an ash-rich fuel such as ASR. The findings may have applications in demonstrating the induction of oxygen-carrying ability in bed materials or for metal recycling through the separation of ash particles from the bed material.

In dual fluidized bed (DFB) gasification, the interaction of the bed material with the fuel ash leads to the development of a bed catalytic activity toward tar-abating reactions. However, the formation of ash layers may also be detrimental to the process, especially in terms of the uncontrolled transport of oxygen from the combustor to the gasifier. A few previous studies investigating the development of catalytic activity in bed materials have also reported the development of oxygen transport, although the latter was not the focus of these studies. This work verifies that olivine and feldspar, which are bed materials with limited and no intrinsic oxygen transport capacities, respectively, develop the capacity to transport oxygen by interacting with the fuel ash. We correlate this development in oxygen transport to the development of bed catalytic activity. Our results imply that the volatile species that are released by the bed material to the gas phase in the gasifier contribute to the developed oxygen transport. Sulfur is proposed as one of the components of these volatile species, and its potential contribution is investigated. For feldspar, the results support the notion that sulfur is involved in the transport of oxygen, both as a volatile species and as a species remaining within the ash layer. The results also suggest that other species, including volatile ones, are involved. These aspects are investigated based on experimental results obtained from the Chalmers gasifier - a semi-industrial-scale DFB gasifier - and are isolated in laboratory-scale experiments.

Quartz, feldspar, and olivine are minerals commonly used as bed materials for dual fluidized bed gasification of biomass. During their interaction with biomass ash, the materials develop surface layers rich in ash-derived elements. These layers decrease the concentration of tar which is an unwanted side product of gasification. The interactions of quartz, feldspar, and olivine with woody biomass ash leading to the formation of active layers were studied with X-ray diffraction, scanning electron microscopy- energy dispersive X-ray spectroscopy, and iime-of-flight secondary ion mass spectrometry, and the results were compared to calculations done with FactSage. It was found that the interaction causes the formation of three-layered structures for all materials: a Mg-rich surface layer, a Ca-rich intermediate layer, and an inner layer which varies among the three materials. For quartz and feldspar, the integration of Ca and Mg into the structure causes a transition by depolymerizing the tectosilicate structure via an inosilicate intermediate to finally a nesosilicate. As the olivine structure is a nesosilicate from the beginning, no further depolymerization of the silicate structure can occur and a substitution of Mg by Ca occurs, leading to an accumulation of expelled MgO on the surface. The interaction of the materials with K was found to differ, causing melt formation for quartz, a substitution of Na-rich feldspar by K-rich feldspar, and the formation of feldspathoids for alkali feldspar, or retention as a separate phase for olivine.

Selecting a suitable bed material for the thermochemical conversion of a specific feedstock in a fluidized bed system requires identification of the characteristics of potential bed materials. An essential part of these characteristics is the interaction of the bed material with feedstock ash in a fluidized bed, which leads to layer formation and morphology changes. For this purpose, the interaction of feldspar bed material with the main ash-forming elements in wood ash (Ca, K, Mg, Si) in an indirect gasification system was analyzed using SEM-EDS, XRD, and thermodynamic modeling. In part 1 of this work (DOI: 10.1021/acs.energyfuels.9b01291), the layer formation on K-feldspar dominated by Ca reaction and ash deposition was investigated. The aim of this second part of the work was to determine the time-dependent layer formation on Na-feldspar and compare the results with the findings for K-feldspar. Interaction of Na-feldspar with ash-derived elements resulted in different layers on Na-feldspar: K reaction layers, where K replaced Na and Si shares decreased; Ca reaction layers, where Ca enriched and reacted with the Na-feldspar; and ash deposition layers, where wood ash elements accumulated on the surface. Ca reaction layers were formed first and became continuous on the surface before K reaction layers and ash deposition layers were detected. Cracks and crack layer formation in the Na-feldspar particles were found after several days of operation. The layer compositions and growth rates indicate that the diffusion of Ca and K plays an essential role in the formation of Ca reaction and K reaction layers. The reaction with Ca and the crack formation coincide with the interaction previously found for quartz and K-feldspar. In contrast to K-feldspar, Na-feldspar showed high potential for reaction with K. The findings indicate that the reaction of Na- feldspar with ash-derived K makes Na-feldspar a less stable bed material than K-feldspar during the thermochemical conversion of K-rich feedstocks in a fluidized bed system.

Dual atmosphere conditions have been shown to be detrimental for the ferritic stainless steel interconnects used in solid oxide fuel cells (SOFC) under certain conditions. In the present work, we analyze the influence of pre-oxidation on corrosion resistance in dual atmosphere with regard to two parameters: the pre-oxidation time and the pre-oxidation location (pre-oxidation layer on the air-facing side or the hydrogen-facing side). The steel AISI 441 is investigated and pre-oxidation is achieved in air at 800 °C. To examine the influence of pre-oxidation time on corrosion behavior, five different pre-oxidation times are used: 0, 11, 45, 180, and 280 min. The samples are exposed discontinuously to dual atmosphere for 1000 h at 600 °C. Photographs, taken throughout the exposure, show that the pre-oxidation time correlates with the onset of breakaway corrosion. To analyze the influence of pre-oxidation location on corrosion behavior, the samples are pre-oxidized for 180 min, and then a pre-oxidation layer is removed from one side of the sample. Subsequent dual atmosphere exposure at 600 °C for 500 h shows that the pre-oxidation layer on the hydrogen-facing side is more important for corrosion resistance in dual atmosphere than the pre-oxidation layer on the air-facing side.

Sleep health is a good indicator to a person’s overall health status and general well-being. Proper sleep is one of the most important factors to healthy immunity. Protecting and restoring sleep quality are vital to well-being. Problems such as insomnia, obstructive sleep apnea, fatigue, and hypersomnia can all affect the quality of a person’s sleep. There are over 35 million people living with HIV/AIDS infection in the world. These people suffer from many of the same sleep problems and often have more frequent or more severe symptoms. It is not clear if this is from the disease, the medications, or some other factors. HIV-positive persons need good sleep quality to maintain their immune system and help keep the disease from progressing. Treatments for sleep disorders in HIV need to be considered carefully. Interventions should start with the least invasive progress to more invasive therapies and be monitored carefully.

Olivine bed material used in an aging experiment for indirect gasification in the Chalmers 2–4-MWth DFB gasifier was investigated with the aim to determine the mechanism of layer formation around the particles upon exposure to gasification conditions. The collected samples were exposed for 1, 2 and 4 days. The development of ash layer around the bed material particles was studied with different analysis methods. Formation of Ca3Mg(SiO4)2 and MgO was confirmed by X-ray diffraction (XRD). Cross-sections of the bed material samples were prepared using Broad Ion Beam (BIB) milling and were further analyzed with Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDS). The analysis of the produced cross-sections revealed the formation of a Mg-rich surface layer on top of the Ca-rich ash layer. Minor amounts of K were also found near the sample surface. Based on the results from the characterization techniques, a reaction mechanism involving the transition of Mg2SiO4 with CaO to MgO and Ca3Mg(SiO4)2 was suggested which was confirmed by equilibrium calculations. This mechanism was supported by Transmission Electron Microscopy (TEM) analysis where diffraction patterns corresponding to MgO were found. TEM-EDS line-scan revealed the presence of ash components in the ash layer such as P and Ti at locations coinciding with high levels of Ca which indicates the formation of Ca3(PO4)2 and CaTiO3. The results presented provide detailed information on the composition of the ash layer which can be used to fully understand the mechanism responsible for the formation of catalytically active ash layers.

Patients living with human immunodeficiency virus/acquired immunodeficiency syndrome (PLWHA) are at increased risk of cardiovascular disease because of advances in human immunodeficiency virus/acquired immunodeficiency syndrome treatment and increased life expectancy. Cardiovascular health promotion in PLWHA includes strategies for risk factor reduction, disease prevention, early detection, and treatment of cardiovascular disease.

This study describes physical activity level in outpatients with schizophrenia spectrum disorders (SSD) using extended-wear pedometers. Demographic data, body fat and body mass index (BMI) measures were obtained from 24 outpatients. Participants were provided extended-wear pedometers and instructed to wear them during waking hours for 1 week. More than 79% of subjects met Centres for Disease Control (CDC) obesity criteria. Participants wore pedometers, on average, 6 days during the week. Men walked more steps, walked longer distances, and burned more calories each day; differences were statistically significant for steps and distance on days 3 (t = 2.12, P = 0.045) and 5 (t = 2.19, P = 0.04). Higher percent body fat and BMI were significantly associated with fewer steps walked on most days. Extended-wear pedometers are an easy-to-use, cost-effective way to document physical activity and evaluate efforts to help this vulnerable group achieve activity-related health improvements.

Interconnects are an integral part of solid oxide fuels cells (SOFC) and, even when ferritic stainless steel is used, their contribution to the overall stack cost is still substantial. Stainless steels that are produced in large volumes such as AISI 441 are particularly attractive from a cost perspective. However, in our previous work, we have shown that this material suffers from severe corrosion in dual atmosphere exposure at 600 °C typical for Intermediate Temperature-SOFC (IT-SOFC) applications. We have seen a beneficiary effect of pre-oxidation and will, in the present work, closely examine this effect. By varying pre-oxidation parameters such as length and location (anode vs. cathode side) of the oxide layer, we were able to clarify the importance of pre-oxidation. Furthermore, we see a correlation between the length of pre-oxidation, and therefore the thickness of the oxide layer, and the onset of breakaway oxidation. This correlation is expected to allow for accelerated life time testing with respect to dual atmosphere corrosion. For our studies we chose five different pre-oxidation times: 0 min, 11 min, 45 min, 180 min and 280 min. The dual atmosphere exposure was conducted at 600 °C and the exposure was interrupted after 24 h, 168 h and 500 h and photographs were taken of the air facing side of each steel sample. By means of the photographs, we can clearly correlate length of pre-oxidation with onset of breakaway. Our findings are further supported by Scanning Electron Microscopy/Energy Dispersive X-Ray (SEM/EDX) analysis. An additional study was performed to get a clear picture of the beneficial effects of the pre-oxidation layer in relation to its location. To examine this question the samples were pre-oxidized and subsequently the resulting oxide layer was removed from one side of the sample via mechanical polishing. The samples were then exposed with the pre-oxidized surface either facing the fuel side or facing the air side. The exposure was interrupted after the same intervals as in the aforementioned experiment to visualize the progress of breakaway oxidation. Also these samples were analyzed using photographs and SEM/EDX analysis.

This study describes physical activity level in outpatients with schizophrenia spectrum disorders (SSD) using extended-wear pedometers. Demographic data, body fat and body mass index (BMI) measures were obtained from 24 outpatients. Participants were provided extended-wear pedometers and instructed to wear them during waking hours for 1 week. More than 79% of subjects met Centres for Disease Control (CDC) obesity criteria. Participants wore pedometers, on average, 6 days during the week. Men walked more steps, walked longer distances, and burned more calories each day; differences were statistically significant for steps and distance on days 3 (t = 2.12, P = 0.045) and 5 (t = 2.19, P = 0.04). Higher percent body fat and BMI were significantly associated with fewer steps walked on most days. Extended-wear pedometers are an easy-to-use, cost-effective way to document physical activity and evaluate efforts to help this vulnerable group achieve activity-related health improvements.

Identification of procedures to document physical activity is critical to developing interventions to improve physical health. The purpose of this pilot study was to describe the feasibility and acceptability of pedometers to document physical activity in patients with schizophrenia spectrum disorders (SSDs). Twenty-four outpatients were provided with extended-wear pedometers and instructed to wear them daily for 1 week without altering their usual activities. All participants completed the 1-week data collection period. Twenty-one (87.5%) participants wore their pedometer at least 6 of the 7 days. Difficulties with the pedometers were few and minor. These preliminary findings indicate that a majority of individuals with SSDs are willing to wear pedometers for activity monitoring and can do so with few problems. Possible barriers to the use of extended-wear pedometers in this group include cognitive and memory deficits. Future investigations should test concurrent validity by examining the correlations between pedometer data and self-reported activity level.