| 1. |
- Draxler, Joar, et al.
(author)
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A numerical model for simulating the effect of strain rate on eutectic band thickness
- 2020
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In: Welding in the World. - : Springer. - 0043-2288 .- 1878-6669. ; 64:10, s. 1635-1658
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Journal article (peer-reviewed)abstract
- Large tensile strains acting on the solidifying weld metal can cause the formation of eutectic bands along grain boundaries. These eutectic bands can lead to severe liquation in the partially melted zone of a subsequent overlapping weld. This can increase the risk of heat-affected zone liquation cracking. In this paper, we present a solidification model for modeling eutectic bands. The model is based on solute convection in grain boundary liquid films induced by tensile strains. The proposed model was used to study the influence of strain rate on the thickness of eutectic bands in Alloy 718. It was found that when the magnitude of the strain rate is 10 times larger than that of the solidification rate, the calculated eutectic band thickness is about 200 to 500% larger (depending on the solidification rate) as compared to when the strain rate is zero. In the paper, we also discuss how eutectic bands may form from hot cracks.
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| 2. |
- Edlund, Erik, 1986, et al.
(author)
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A design path for the hierarchical self-assembly of patchy colloidal particles
- 2015
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In: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 11:19, s. 3913-3919
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Journal article (peer-reviewed)abstract
- Patchy colloidal particles are promising candidates for building blocks in directed self-assembly. To be successful the surface patterns need to be simple enough to be synthesized, while feature-rich enough to cause the colloidal particles to self-assemble into desired structures. Achieving this is a challenge for traditional synthesis methods. Recently it has been suggested that surface patterns themselves can be made to self-assemble. In this paper we present a design path for the hierarchical targeted self-assembly of patchy colloidal particles based on self-assembling surface patterns. At the level of the surface structure, we use a predictive method utilizing the universality of stripes and spots, coupled with stoichiometric constraints, to cause highly specific and functional patterns to self-assemble on spherical surfaces. We use a minimalistic model of an alkanethiol on gold as a demonstration, showing that even with limited control over the interaction between surface constituents we can obtain patterns that cause the colloidal particles themselves to self-assemble into various complex geometric structures, such as strings, membranes, cubic aggregates and colloidosomes, as well as various crystalline patterns.
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| 3. |
- Edlund, Erik, 1986, et al.
(author)
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Chiral Surfaces Self-Assembling in One-Component Systems with Isotropic Interactions
- 2012
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In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 108:16, s. 165502-
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Journal article (peer-reviewed)abstract
- We show that chiral symmetry can be broken spontaneously in one-component systems with isotropic interactions, i.e., many-particle systems having maximal a priori symmetry. This is achieved by designing isotropic potentials that lead to self-assembly of chiral surfaces. We demonstrate the principle on a simple chiral lattice and on a more complex lattice with chiral supercells. In addition, we show that the complex lattice has interesting melting behavior with multiple morphologically distinct phases that we argue can be qualitatively predicted from the design of the interaction.
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| 4. |
- Edlund, Erik, 1986, et al.
(author)
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Designing Isotropic Interactions for Self-Assembly of Complex Lattices
- 2011
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In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 107:8, s. 085503-
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Journal article (peer-reviewed)abstract
- We present a direct method for solving the inverse problem of designing isotropic potentials that cause self-assembly into target lattices. Each potential is constructed by matching its energy spectrum to the reciprocal representation of the lattice to guarantee that the desired structure is a ground state. We use the method to self-assemble complex lattices not previously achieved with isotropic potentials, such as a snub square tiling and the kagome lattice. The latter is especially interesting because it provides the crucial geometric frustration in several proposed spin liquids.
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| 5. |
- Edlund, Erik, 1986, et al.
(author)
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Novel Self-Assembled Morphologies from Isotropic Interactions
- 2011
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In: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 107:8, s. 085501-
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Journal article (peer-reviewed)abstract
- We present results from particle simulations with isotropic medium range interactions in two dimensions. At low temperature novel types of aggregated structures appear. We show that these structures can be explained by spontaneous symmetry breaking in analytic solutions to an adaptation of the spherical spin model. We predict the critical particle number where the symmetry breaking occurs and show that the resulting phase diagram agrees well with results from particle simulations.
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| 6. |
- Edlund, Erik, 1986, et al.
(author)
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Predicting self-assembled patterns on spheres with multicomponent coatings
- 2014
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In: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 10:17, s. 2955-2960
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Journal article (peer-reviewed)abstract
- Patchy colloids are promising candidates for building blocks in directed self-assembly, but large scale synthesis of colloids with controlled surface patterns remains challenging. One potential fabrication method is to self-assemble the surface patterns themselves, allowing complex morphologies to organize spontaneously. For this approach to be competitive, prediction and control of the pattern formation process are necessary. However, structure formation in many-body systems is fundamentally hard to understand, and new theoretical methods are needed. Here we present a theory for self-assembling pattern formation in multi-component systems on the surfaces of colloidal particles, formulated as an analytic technique that predicts morphologies directly from the interactions in an effective model. As a demonstration we formulate an isotropic model of alkanethiols on gold, a suggested system for directed self-assembly, and predict its morphologies and transitions as a function of the interaction parameters.
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| 7. |
- Edlund, Erik, 1986, et al.
(author)
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Using the uncertainty principle to design simple interactions for targeted self-assembly
- 2013
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In: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 139:2, s. 024107-
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Journal article (peer-reviewed)abstract
- We present a method that systematically simplifies isotropic interactions designed for targeted self-assembly. The uncertainty principle is used to show that an optimal simplification is achieved by a combination of heat kernel smoothing and Gaussian screening of the interaction potential in real and reciprocal space. We use this method to analytically design isotropic interactions for self-assembly of complex lattices and of materials with functional properties. The derived interactions are simple enough to narrow the gap between theory and experimental implementation of theory based designed self-assembling materials.
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| 8. |
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| 9. |
- Lindgren, Erik, 1972-
(author)
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Cardiac Arrest – mechanical chest compressions, gender differences and coronary angiography
- 2020
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Doctoral thesis (other academic/artistic)abstract
- Cardiac arrest is a major health problem with over 6000 cases of out-of-hospital cardiac arrest (OHCA) and 2500 cases of in-hospital cardiac arrest (IHCA) per year in Sweden. Survival are low. Many factors affect the chances of survival, including effective cardiopulmonary resuscitation and optimal post resuscitation care. These thesis involve these areas. Paper I+II describe a randomized clinical trial (n=2589). We compared a novel CPR algorithm with defibrillations during ongoing chest compressions delivered with a mechanical chest compression device and manual CPR according to guidelines. We found no difference in 4-hour survival, 23.6% with mechanical CPR and 23.7% with manual CPR. The vast majority of survivors in both groups had good neurological outcomes by 6 months. Paper III is a registry study (n=1498). We investigated impact of gender in performance and findings of early coronary angiography (CAG) and percutaneous coronary intervention (PCI), comorbidity and outcome among OHCA victims with an initially shockable rhythm. We found no difference between men and women in rates of ST-elevation/left bundle branch block (LBBB), 40% vs. 38% or rates of CAG, 45% vs. 40%. Among patients without ST-elevation/LBBB more men than women had CAG followed by PCI, 59% vs. 42% (P=0.03) and more advanced coronary artery disease. We found no association between gender and use of early CAG. Paper IV is a retrospective observational single centre study (n=423) of ICU treated victims of cardiac arrest. OHCA and IHCA were compared regarding comorbidity, characteristics of the arrest, treatment including CAG and CAG findings and outcome. OHCA patients had less preexisting comorbidity, lower rates of bystander CPR 71% vs 100% (p<0.001) and longer time to return of spontaneous circulation, 20 vs 10 minutes (p<0.001). OHCA patients more often had a shockable first rhythm, 47% vs 13% (p<0.001) and CA without any obvious non-cardiac origin, 77% vs 50% (p<0.001). OHCA patients more often underwent early CAG, 52% vs 25% (p<0.001) but no difference in rates of subsequent PCI or angiogram with at least one significant stenosis was seen. OHCA and IHCA did not differ in 30-days survival, 42% vs 41% or 1-year survival, 39% vs 33%
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| 10. |
- Månsson, Linda, et al.
(author)
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Older adults' preferences for, adherence to and experiences of two self-management falls prevention home exercise programmes : a comparison between a digital programme and a paper booklet
- 2020
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In: BMC Geriatrics. - : BioMed Central. - 1471-2318. ; 20:1
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Journal article (peer-reviewed)abstract
- Background: Fall prevention exercise programmes are known to be effective, but access to these programmes is not always possible. The use of eHealth solutions might be a way forward to increase access and reach a wider population. In this feasibility study the aim was to explore the choice of programme, adherence, and self-reported experiences comparing two exercise programmes – a digital programme and a paper booklet.Methods: A participant preference trial of two self-managed fall prevention exercise interventions. Community-dwelling adults aged 70 years and older exercised independently for four months after one introduction meeting. Baseline information was collected at study start, including a short introduction of the exercise programme, a short physical assessment, and completion of questionnaires. During the four months intervention period, participants self-reported their performed exercises in an exercise diary. At a final meeting, questionnaires about their experiences, and post-assessments, were completed. For adherence analyses data from diaries were used and four subgroups for different levels of participation were compared. Exercise maintenance was followed up with a survey 12 months after study start.Results: Sixty-seven participants, with mean age 77 ± 4 years were included, 72% were women. Forty-three percent chose the digital programme. Attrition rate was 17% in the digital programme group and 37% in the paper booklet group (p = .078). In both groups 50–59% reported exercise at least 75% of the intervention period. The only significant difference for adherence was in the subgroup that completed ≥75% of exercise duration, the digital programme users exercised more minutes per week (p = .001). Participants in both groups were content with their programme but digital programme users reported a significantly higher (p = .026) degree of being content, and feeling supported by the programme (p = .044). At 12 months follow-up 67% of participants using the digital programme continued to exercise regularly compared with 35% for the paper booklet (p = .036).Conclusions: Exercise interventions based on either a digital programme or a paper booklet can be used as a self-managed, independent fall prevention programme. There is a similar adherence in both programmes during a 4-month intervention, but the digital programme seems to facilitate long-term maintenance in regular exercise.
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