| 1. |
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| 2. |
- Guío-Pérez, Diana Carolina, 1985, et al.
(författare)
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Effective drag on spheres immersed in a fluidized bed at minimum fluidization—Influence of bulk solids properties
- 2023
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Ingår i: Canadian Journal of Chemical Engineering. - : Wiley. - 1939-019X .- 0008-4034. ; 101:1, s. 210-226
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this work are to elucidate the effects that bulk solids properties have on the effective drag experienced by large spheres immersed in an emulsion of group-B solids under minimum fluidization conditions and to analyze the ways in which the different suspensions react towards different applied shear rates. To investigate this, magnetic particle tracking was applied to resolve the trajectory of falling-sphere measurements in which the size, density, and sphericity of the bulk solids were varied as well as the size and density of the spherical tracers. The resulting experimental scope included both rising and sinking tracers as well as full segregation and in-bed stagnation of the tracers. The set-up provided highly resolved tracer trajectories, from which the drag experienced by the sphere can be calculated. For sinking tracers, the results showed that an increase in bulk solids size, angularity, and density reduced the terminal velocity of the sphere. This effect correlated well with the bed expansion and Hausner ratio, indicating that a reduced void space among the bulk solids is the main reason for the increase in motion resistance. At lower shear rates, namely, during the de-acceleration towards the stagnant state, beds of larger, more angular, or denser bulk solids yield lower levels of shear stress. The angle of repose of the bulk solids correlated with the rate at which the emulsion thins with increasing shear rate. For rising tracers, shear stress did not show any significant dependency on the properties of the bulk solids.
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| 3. |
- Köhler, Anna, 1989, et al.
(författare)
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Rheological effects of a gas fluidized bed emulsion on falling and rising spheres
- 2021
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Ingår i: Powder Technology. - : Elsevier BV. - 1873-328X .- 0032-5910. ; 393, s. 510-518
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Tidskriftsartikel (refereegranskat)abstract
- To enable the mechanistic description of the mixing of larger particles in gas-fluidized beds in models (e.g. fuel particles in combustors), knowledge about the rheology of the bed emulsion is required. Here, it is crucial to determine the drag on large fuel-alike particles. This work presents the experimental work on the fate of 13 different solid spheres falling or rising through a bed of air and glass beads at minimum fluidization. The trajectories of the tracer are highly resolved (sampling rate of 200 Hz) by means of magnetic particle tracking, this previously unmet accuracy allows disclosing the complex rheological behavior of gas-solids fluidized bed emulsions in terms of drag on immersed objects. The trajectories reveal that none of the tracers reach terminal velocity during their fall and rise through the bed. The shear stress is obtained through the drag force by solving the equation of motion for the tracer. The data reveal particularities of the bed rheology and clear differences of its effect on rising and falling particles. When studying the shear stress over the characteristic shear rate of each tracer, it can be seen that the stress of the bed on the tracers is dominated by a yield stress, with a somewhat smaller contribution of the shear stress. For rising tracers this last contribution is almost negligible. The falling tracers show strong interaction with the bed emulsion, resulting in a fluctuating shear stress, which increases with tracer size and density. The stagnation of some tracers at low shear rates reveals a viscoplastic behavior of the bed emulsion, exhibiting a typical yield stress that showing a clear dependence on the tracer diameter and buoyant density. The concept of yield gravity is used in order to introduce a normalized shear stress which provides additional verification of the experimental observations in relation to the influence of tracer size and relative density on the shear stress.
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| 4. |
- Norderyd, Ola, et al.
(författare)
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Oral health of individuals aged 3-80 years in Jönköping, Sweden, during 40 years (1973-2013) : I. Review of findings on oral care habits and knowledge of oral health.
- 2015
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Ingår i: Swedish Dental Journal. - 0347-9994. ; 39:2, s. 57-68
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the this study was to present data on oral care habits and knowledge of oral health in 2013, and to compare these data with results from a series of four previous cross-sectional epidemiological studies. All these studies were carried out in the city of Jönköping, Sweden, in 1973, 1983, 1993, 2003, and 2013. The 1973 study constituted a random sample of 1,000 individuals evenly distributed in the age groups 3, 5, 10, 15, 20, 30, 40, 50, 60, and 70 years. The same age groups with addition of a group of 80-year-olds were included in the 1983, 1993, 2003, and 2013 studies, which comprised 1,104; 1,078; 987; and 1,010 individuals, respectively.A questionnaire about dental care habits and knowledge of oral health was used. The questionnaire contained the same questions in all the five studies, although some had to be slightly modernised during the 40-year period.During the period 1973–2013, a continous increase of individuals in the age group 20–60 years were treated by the Public Dental Service amounting to about 50%. Almost 70% of the 70- and 80-year-olds were treated by private practitioners. In 2013, 10–20% of the individuals in the age groups 30–40 years did not regularly visit neither Public Dental Service nor a private practitioner. The corresponding figures for the individuals 50–80 years old were 4–7%. Similar number of avoidance was reported in the previous studies.In the survey 2013, about 20–30% of the individuals in the age groups 20–50 felt frightened, sick, or ill at ease at the prospect of an appointment with the dentist. These findings were in agreement with the results from the surveys 1973–2003. Among the younger age groups, 10–15 years, a reduction in self-reported "ill at ease" was found in the surveys 2003 and 2013 compared to the previous surveys in this series.In 2013, the knowledge of the etiology of caries was known by about 60% of the individuals which was similar to that reported 1973–2003. Twenty per cent of the individuals stated that they did not know which etiological factors that causes caries. This percentage was equivalent during the period 1973–2013. About 85% of the individuals in all age groups brushed their teeth with fluoride tooth paste at least two times a day. These frequencies have gradually increased during the 40-year period.Around 40% in the age groups 50–80 years used toothpicks regularly in 2013. This is a about 1/3–1/2 less compared to 2003. In the age groups 20–40 years 3–14% used toothpicks for proximal cleaning in 2013.In 2013, about 35% of the individuals never consumed soft drinks, in comparison with 20% in 2003. In the age groups 3–20 years about 20% were consuming soft drinks every day or several times a week, which is a reduction by half compared to 2013
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| 5. |
- Norderyd, Ola, et al.
(författare)
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Oral health of individuals aged 3-80 years in Jönköping, Sweden during 40 years (1973-2013) : II. Review of clinical and radiographic findings
- 2015
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Ingår i: Swedish Dental Journal. - 0347-9994. ; 39:2, s. 69-86
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this epidemiological study performed in 2013 was to analyze various clinical and radiographic data on oral health and compare the results to those of four cross-sectional studies carried out 1973–2003. In 1973, 1983, 1993, 2003, and 2013 random samples of 1,000; 1,104; 1,078; 987; and 1,010 individuals, respectively, were studied. The individuals were evenly distributed in the age groups 3, 5, 10, 15, 20, 30, 40, 50, 60, 70, and 80 years. Eighty-year-olds were not included in 1973. All subjects were inhabitants of the city of Jönköping, Sweden.The clinical and radiographic examination assessed edentulousness, removable dentures, implants, number of teeth, caries, restorations, oral hygiene, calculus, periodontal status, and endodontic treatment.The frequency of edentulous individuals aged 40–70 years was 16, 12, 8, 1, and 0.3% in 1973, 1983, 1993, 2003, and 2013, respectively. No complete denture wearer younger than 80-years old was found in 2013. During the 40-year period, the mean number of teeth in the age groups 30–80 years increased. In 2013, the 60-year-olds had nearly complete dentitions. Implants were found in all age groups from 30 years of age. The total number of individuals with implants was 36 in 2013. This was higher than earlier surveys, 4 in 1993, and 18 in 2003.The percentage of children and adults without caries and restorations increased during the 40-year period. It was found that the percentage of caries-free 3- and 5-year-olds were 79% and 69%, respectively, of the individuals in 2013. In the age groups 10–20 years, the percentage of caries-free individuals increased between 2003 and 2013. In 2013, 43% of the 15-year-olds were completely free from caries and restorations compared to 20% in 2003. In all age groups 5–60 years, DFS was lower in 2013 compared to the earlier examinations. There was no major change in DFS between 2003 and 2013 in the age groups 70 and 80 years. The most obvious change was the decrease in number of FS over the 40- year period of time. Regarding crowned teeth the most clear changes between 1973 to 2013 were the decrease in percentage of crowned teeth in the age goups 40 and 50-year-olds. The percentage of endodontically treated teeth decreased between 1973 and 2013 in all age groups.In age groups 10–30-year-olds a major reduction from about 30% to 15% in mean plaque score was seen between 1973–2003. Only a minor change in plaque score was seen during the last decade. For the age groups 40 years and older, a decrease in the percentage of surfaces with plaque was observed between 2003–2013. The percentage of tooth sites with gingivitis was for 20 years and older about 40% in 1973. In 2013, the percentage was about 15%. The frequency of sites with gingivitis was generally lower in 2013 compared with the other years, 1973–1993.The percentage of individuals with probing pocket depths >4mm increased with age. Between 2003–2013 a clear reduction was seen in all age groups in frequency of individuals with probing pocket depth >4mm. Over the 40-year period an increase in the number of individuals with no marginal bone loss and a decrease in the number of subjects with moderate alveolar bone loss were seen.The continuous improvement in oral health and the reduced need of restorative treatment will seriously affect the provision of dental helath care and dental delivery system in the near future.
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| 6. |
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| 7. |
- Anastassaki Köhler, Alkisti, et al.
(författare)
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Prevalence of symptoms and signs indicative of temporomandibular disorders in children and adolescents : A cross-sectional epidemiological investigation covering two decades
- 2009
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Ingår i: European Archives of Paediatric Dentistry. - 1818-6300. ; 10:Suppl. 1, s. 16-25
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Tidskriftsartikel (refereegranskat)abstract
- AIM: These were to 1) estimate the prevalence of subjective symptoms and clinical signs of temporomandibular disorders (TMD) in children and adolescents in the city of Jönköping, Sweden, 2) follow possible variations in TMD signs and symptoms over a 20-year period, and 3) study possible associations between TMD symptoms and signs and factors of interest. DESIGN: About 100 individuals in the age groups of 3, 5, 10 and 15 years participated in crosssectional stratified epidemiological investigations in 1983, 1993 and 2003. METHODS: All participants were asked to fill in a questionnaire including questions on general and oral health, dental care habits and some sociodemographic issues. More specific questions recorded the presence or absence of subjective symptoms: tiredness in the jaws on awakening or during chewing; clicking sounds or crepitations from the temporomandibular joints (TMJs); locking/ catching of the mandible; luxation of the mandible; reduced jaw movement capacity; pain during jaw movements; other pain conditions in the jaws or in the TMJ regions. Subjects were examined clinically at each time period for; jaw mobility (maximum jaw opening including vertical overbite, maximum laterotrusion to the right and to the left, maximum protrusion); TMJ function (normal function, deflection on jaw opening of > 2 mm, TMJ clicking or crepitations, TMJ locking, TMJ luxation); pain on jaw movement (no pain on movements, pain on one movement, pain on more than one movement); muscle pain (no muscle pain, pain on palpation in 1-3 sites, pain on palpation in > 3 sites); TMJ pain (no joint pain, pain on lateral palpation of one or both joints, pain on posterior palpation of one or both joints). No functional examination of the masticatory system was performed in children aged 3 and 5 years. RESULTS: TMD-related symptoms were very rare in 3- and 5-year-olds. In the age groups of 10- and 15-yearolds, 5-9% of the participants reported more severe symptoms, up to 50% showed one or more TMD signs, while it was estimated that 1-2% were in need of TMD treatment. Several symptoms and signs increased with age. No gender differences, with the exception of recurrent headache, were noted. Oral parafunctions were reported by 11-47%. Apart from a few variables, no statistically significant changes in the prevalence of TMD symptoms and signs were observed over the 20-year period. Clenching/grinding of teeth and general health factors were found to be associated with TMD symptoms and signs. CONCLUSIONS: The prevalence of more severe TMD symptoms and signs in children and adolescents was generally low in all three examinations and did not change significantly during the 20-year period. Increasing age, general health factors and oral parafunctions were associated with TMD symptoms and signs in 10- and 15-year-olds.
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| 8. |
- Birkeland, Anna-Lena, 1955-
(författare)
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Psychosocial aspects of living with congenital heart disease : child, family, and professional perspectives
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: The vast majority of infants born with congenital heart disease (CHD) reach adulthood because of the developments in cardiology in recent decades. This thesis aims to describe the psychosocial situation of child/adolescent cardiac patients and their families, investigate the situation faced by parents and siblings initially and over time, investigate the approaches paediatric cardiologists use in encountering the family, and describe the teamwork occurring in paediatric cardiology teams (PCTs) in Sweden.Theoretical framework: The theoretical framework was based on a quality of life model applied to children, a stress-coping model, and a psychosocial approach including support, profession, and teamwork.Methods: The research combines quantitative data collection/analysis and qualitative research interviews/content analysis.Results: Complexity: The three grades of medical complexity differed regarding the number and severity of psychosocial symptoms, the children with the most complex CHD having the most severe symptoms. The most frequent symptoms in the whole patient group regarding various spheres were: healthcare and treatment-related needs in the external sphere, family symptoms in the interpersonal sphere, and mental/psychosomatic symptoms in the personal sphere.Coping: Being informed of a child’s/sibling’s heart disease has emotional consequences, so information, communication, and support are essential. Breaking the news of a child’s disease can be described as a turning point still significant after ten years. The professionalism of the doctor’s approach in breaking the news is crucial.Profession: Among paediatric cardiologists, how to break bad news to a family is an important concern, evident in findings regarding the significance of trust and confidence and the use of various emotional positions. Paediatric cardiologists commonly wish to be skilled at handling this situation, and attaining the needed skills calls for reflection, education, and sharing experience.Team: PCTs in Sweden aim and try to work in a structured way. In PCTs, there is a need for leadership, resource coordination, coaching, and a forum for joint reflection. Dependence on the physician on the team was identified in all PCTs. The challenge of managing increasing complexity at both the family and system levels requires interprofessional teams.Conclusions: These studies illustrate the psychosocial complexity and the need of psychosocial support. Emotional consequences, communication, information and support are essential both for the children, parents/families and for the professionals. To manage this complexity organizational alteration action plans are required. There is a need for a forum to stimulate dialogue and common reflection in the local PCT and at the regional and national centres.
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| 9. |
- Ejhed, Helene, et al.
(författare)
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Feasibility study of net load of metals : Particulate fraction and retention of metals in lakes and rivers
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Belastning av metaller på vattenmiljön beror på bruttobelastning från primära och sekundära källor, men även på transport och fastläggning av metallerna inom vattenmiljön. Målet i denna studie var att undersöka möjligheten att använda retentionsmodeller/metoder för att beräkna nettobelastning av metaller på nationell skala med relativt hög upplösning. Detta för att uppfylla krav på internationell rapportering från Sverige. I denna studie har fokus lagts på litteraturstudier av retentionsprocesserna av metaller, test av två retentionsmodeller och en massbalansmetod. Dessutom har speciellt fokus lagts på att tillföra kunskap om partiklar, kolloider och lösta former av metaller i svenska vattendrag och sjöar.Studier av metallretention som finns redovisade i litteraturen visar att det är stor variation i resultaten, från ett par procent upp till nära 100 %. Retentionen är i de flesta studier fördelad enligt: Pb>Cd, Zn, Cu> Ni, Cr. Retentionen i Mälaren har i en studie beräknats till max 60 % för Cd , 50 % för Zn och 30 % för Cu. I en annan studie har retentionen i Vättern beräknats för Cd till 60 % och för Hg till 97 %. Avrinningsområdena till de stora sjöarna är inte fullständigt övervakade med avseende på tillförseln av metaller, vilket innebär att tester av retentionsmodellerna inte kunde genomföras i denna studie. Fastläggning av metaller sker genom lagring i sedimenten. Flera artiklar omfattar framgångsrik användning av uppehållstid för vattnet för att beskriva retentionen med modeller och pekar på vikten av kornstorlek i sediment samt mängden partikulärt bundna metaller. Fortsatt arbete bör fokusera på de parametrarna.Den partikulära fraktionen av metallerna Al, Fe, Ni, Cu, Zn och Pb i svenska sjöar och vattendrag har undersökts i denna studie baserat på två metoder; empirisk regression med linjär regression och PLS analys, respektive kemisk speciering med hjälp av programmet VisualMinteq. Linjär regression visades vara den mest användbara metoden för att beräkna partikulärt bunden fraktion av metallerna och bör användas tills att en förbättrad kemisk karakterisering av metallerna blir tillgänglig. Regressionsmetoden fungerar bra för att bestämma partikulär koncentration av Al, Fe och Pb, acceptabelt för Zn och Ni, men dåligt för Cu. Utöver detta har en begränsad studie genomförts av förändringen av Pb kolloidala specier, järnhydroxider och organiskt kol, mellan uppströms och nedströms platser baserat på det nationella miljöövervakningsprogrammet ”Omdrevssjörna” (tidigare Riksinventeringen). Resultaten tyder på att förluster av organiskt material från markanvändning kan ha betydande påverkan på belastning av Pb. Fastläggning av organiskt bundet Pb i vattendragen var större än minerogent bundet Pb. Fortsatta studier av dessa observationer vid andra platser och med andra metaller rekommenderas starkt.Två dynamiska processbaserade metallretentionsmodeller, Lindström och Håkanson-modellen samt QWASI-modellen, har i denna studie framgångsrikt testats avseende metallerna Pb, Cd, Zn och Cu i tre sjöar. En massbalansmodell (FlowNorm) har också framgångsrikt testats i sex vattendrag. Det fanns bara ett fåtal nationellt tillgängliga sjödata enligt urvalet, med flera års övervakning av metallkoncentrationen i inflöde samt utflöde. Antalet sjöar med data kan utökas genom utökade urvalskriterier som föreslås i denna studie för fortsatt arbete med kalibrering och validering av modeller. Båda retentionsmodellerna Lindström och Håkanson samt QWASI gav jämförbara resultat, speciellt av koncentrationen i utflödet. Koncentrationen från sjöarna Innaren och Vidöstern beskrivs bra för alla metaller av båda modellerna. Båda modellerna har däremot beräknat koncentrationen i utflödet från sjön Södra Bergundasjön mycket högre än uppmätt medianhalt. Skillnaden beror troligtvis på överskattad bruttobelastning till Södra Bergundasjön. Testet visar nyttan av retentionsberäkningarna för att validera och korrigera bruttobelastning av metallerna. Lindström och Håkanson-modellen testades vidare i denna studie genom en känslighets- och en osäkerhetsanalys. Modellen var mest känslig för variationen i bruttobelastning. Nyttan av de dynamiska modellerna har vidare testats, som verktyg för att förutsäga effekten av eventuella förändringar av belastningen, vilket illustreras genom scenarioberäkningar i denna studie av Innaren och Vidöstern. Lindström och Håkanson-modellen kräver färre indata än QWASI och rekommenderas för fortsatt arbete.Enbart ett fåtal provplatser var lämpliga för retentionsmodellering med FlowNormprogrammet för vattendrag, och ännu färre data fanns tillgängligt för att beräkna den potentiella retentionen av metaller längs med vattendragen. För att kunna beräkna metallretentionen längs vattendragen på nationell nivå behövs ett annat urvalskriterie än de krav som ställts i denna studie. De platser som fanns tillgängliga för denna studie, visade dock att retention av metaller sker i vattendragen till olika grad. Fortsatt arbete bör därför beakta retention av metaller i både sjöar och vattendrag.Rekommendationer för fortsatt arbete:- Linjär regressionsmodell fungerar bäst för beräkning av den partikulära fraktionen av metaller och bör användas tillsvidare.- Ytterligare undersökningar av kolloidala och partikulära fraktioner, liknande den som genomförts för Pb i denna studie, rekommenderas för andra platser och metaller, vilket även innebär följande rekommendationer för att utöka underlagen: --Provtagning av sediment i de områden där den synoptiska provtagningen ägde rum.- Provtagning av filtrerade och ofiltrerade prover i de områden där den synoptiska provtagningen ägde rum.- Fortsatt arbete med retention av metaller rekommenderas starkt för att förbättra beräkningarna av bruttobelastningen av metallerna.- Öka antalet platser för kalibrering och validering genom föreslagna urvalskriterier.- Tillämpa Lindström och Håkanson-modellen på nationell nivå.
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| 10. |
- Finlay, Roger, et al.
(författare)
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Reviews and syntheses : Biological weathering and its consequences at different spatial levels - from nanoscale to global scale
- 2020
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17:6, s. 1507-1533
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Forskningsöversikt (refereegranskat)abstract
- Plant nutrients can be recycled through microbial decomposition of organic matter but replacement of base cations and phosphorus, lost through harvesting of biomass/biofuels or leaching, requires de novo supply of fresh nutrients released through weathering of soil parent material (minerals and rocks). Weathering involves physical and chemical processes that are modified by biological activity of plants, microorganisms and animals. This article reviews recent progress made in understanding biological processes contributing to weathering. A perspective of increasing spatial scale is adopted, examining the consequences of biological activity for weathering from nanoscale interactions, through in vitro and in planta microcosm and meso-cosm studies, to field experiments, and finally ecosystem and global level effects. The topics discussed include the physical alteration of minerals and mineral surfaces; the composition, amounts, chemical properties, and effects of plant and microbial secretions; and the role of carbon flow (including stabilisation and sequestration of C in organic and inorganic forms). Although the predominant focus is on the effects of fungi in forest ecosystems, the properties of biofilms, including bacterial interactions, are also discussed. The implications of these biological processes for modelling are discussed, and we attempt to identify some key questions and knowledge gaps, as well as experimental approaches and areas of research in which future studies are likely to yield useful results. A particular focus of this article is to improve the representation of the ways in which biological processes complement physical and chemical processes that mobilise mineral elements, making them available for plant uptake. This is necessary to produce better estimates of weathering that are required for sustainable management of forests in a post-fossil-fuel economy. While there are abundant examples of nanometre- and micrometre-scale physical interactions between microorganisms and different minerals, opinion appears to be divided with respect to the quantitative significance of these observations for overall weathering. Numerous in vitro experiments and microcosm studies involving plants and their associated microorganisms suggest that the allocation of plant-derived carbon, mineral dissolution and plant nutrient status are tightly coupled, but there is still disagreement about the extent to which these processes contribute to field-scale observations. Apart from providing dynamically responsive pathways for the allocation of plant-derived carbon to power dissolution of minerals, mycorrhizal mycelia provide conduits for the long-distance trans-portation of weathering products back to plants that are also quantitatively significant sinks for released nutrients. These mycelial pathways bridge heterogeneous substrates, reducing the influence of local variation in C : N ratios. The production of polysaccharide matrices by biofilms of interacting bacteria and/or fungi at interfaces with mineral surfaces and roots influences patterns of production of antibiotics and quorum sensing molecules, with concomitant effects on microbial community structure, and the qualitative and quantitative composition of mineral-solubilising compounds and weathering products. Patterns of carbon allocation and nutrient mobilisation from both organic and inorganic substrates have been studied at larger spatial and temporal scales, including both ecosystem and global levels, and there is a generally wider degree of acceptance of the systemic effects of microorganisms on patterns of nutrient mobilisation. Theories about the evolutionary development of weathering processes have been advanced but there is still a lack of information connecting processes at different spatial scales. Detailed studies of the liquid chemistry of local weathering sites at the micrometre scale, together with upscaling to soil-scale dissolution rates, are advocated, as well as new approaches involving stable isotopes.
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