| 41. |
- Kaplan, Alexander F. H., et al.
(författare)
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Laser induced reduction of iron ore by silicon
- 2023
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Ingår i: Journal of Alloys and Metallurgical Systems. - : Elsevier. - 2949-9178. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Iron ore powder accompanied by Si-powder as a reducing agent, was melted using a high-power laser beam. During laser melting of the two different powder beds placed next to each other, silicon merged and diffused into the iron ore, forming a ternary melt phase Fe-O-Si of around 30–60–10 at%. High speed imaging of the laser melting process as well as subsequent SEM-analysis of the generated nuggets showed the formation of droplets that merge with the surrounding Si- or ore-powder and form distinct domains. Under certain circumstances, the solidifying nuggets, of the order of 0.5–5 mm in size, generated numerous small domains, up to 25 µm, of high purity iron, 90 + at%, surrounded by a matrix of the above mentioned slag. Many of these Fe-domains were created in the vicinity of regions of high Si-content.
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| 42. |
- Keskitalo, M., et al.
(författare)
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The Influence of Shielding Gas and Heat Input on the Mechanical Properties of Laser Welds in Ferritic Stainless Steel
- 2015
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Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 78, s. 222-229
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Tidskriftsartikel (refereegranskat)abstract
- Laser welding of ferritic steel in normal atmosphere gives rise to weld embrittlement and poor formability. This paper demonstrates that the addition of an argon gas shield to the welding process results in tough, formable welds. Post weld heat treatment and microscopic analysis has suggested that the poor ductility of welds produced without a gas shield is, to some extent, the result of the presence of oxides in the weld metal.
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| 43. |
- Lamas, Javier, et al.
(författare)
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The effect of fit-up geometry on melt flow and weld quality in laser hybrid welding
- 2013
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Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 25:3
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid laser-arc welding has a good tolerance to poor fit up as compared to simple laser welding. For a butt joint, the joint fit-up variations can be reduced to two local properties: the gap width and the vertical edge mismatch. The impact of these two properties on the resulting weld quality has been studied systematically in this paper. The original edges as well as the resulting weld surface topography have been scanned in three dimensions in order to study trends. During hybrid welding, the melt flow and the electric arc were observed at the top surface by high speed imaging to analyze the complex fluid flow phenomena.
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| 44. |
- Lampa, Conny, et al.
(författare)
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The Effect of Process Speed on Energy Redistribution in Deep Penetration CO2 Laser Welding
- 2000
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Ingår i: High Temperature Material Processes. - 1093-3611 .- 1940-4360. ; 4:2, s. 213-225
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Tidskriftsartikel (refereegranskat)abstract
- This work discusses energy absorption mechanisms in CO2 laser welding and how they are affected by changes in the process speed. Two main energy absorption processes govern the welding interaction: 1. Fresnel absorption at the keyhole walls. 2. Absorption by the partially ionised metal vapour (or plasma) in the keyhole (laser energy absorbed in this way is re-radiated or conducted to the keyhole walls). A theoretical model of these absorption mechanisms has been developed and shown to agree closely with experimental results. Fresnel absorption has been identified as being dominant over plasma absorption and becomes even more influential as welding speeds are increased.
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| 45. |
- Martini, Paolo G. V., et al.
(författare)
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Recombinant human complement component C2 produced in a human cell line restores the classical complement pathway activity in-vitro: an alternative treatment for C2 deficiency diseases
- 2010
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Complement C2 deficiency is the most common genetically determined complete complement deficiency and is associated with a number of diseases. Most prominent are the associations with recurrent serious infections in young children and the development of systemic lupus erythematosus (SLE) in adults. The links with these diseases reflect the important role complement C2 plays in both innate immunity and immune tolerance. Infusions with normal fresh frozen plasma for the treatment of associated disease have demonstrated therapeutic effects but so far protein replacement therapy has not been evaluated. Results: Human complement C2 was cloned and expressed in a mammalian cell line. The purity of recombinant human C2 (rhC2) was greater than 95% and it was characterized for stability and activity. It was sensitive to C1s cleavage and restored classical complement pathway activity in C2-deficient serum both in a complement activation ELISA and a hemolytic assay. Furthermore, rhC2 could increase C3 fragment deposition on the human pathogen Streptococcus pneumoniae in C2-deficient serum to levels equal to those with normal serum. Conclusions: Taken together these data suggest that recombinant human C2 can restore classical complement pathway activity and may serve as a potential therapeutic for recurring bacterial infections or SLE in C2-deficient patients.
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| 46. |
- Nicoletti, Paola, et al.
(författare)
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Association of Liver Injury From Specific Drugs, or Groups of Drugs, With Polymorphisms in HLA and Other Genes in a Genome-Wide Association Study
- 2017
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Ingår i: Gastroenterology. - : W B SAUNDERS CO-ELSEVIER INC. - 0016-5085 .- 1528-0012. ; 152:5, s. 1078-1089
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: We performed a genome-wide association study (GWAS) to identify genetic risk factors for druginduced liver injury (DILI) from licensed drugs without previously reported genetic risk factors. METHODS: We performed a GWAS of 862 persons with DILI and 10,588 population-matched controls. The first set of cases was recruited before May 2009 in Europe (n = 137) and the United States (n = 274). The second set of cases were identified from May 2009 through May 2013 from international collaborative studies performed in Europe, the United States, and South America. For the GWAS, we included only cases with patients of European ancestry associated with a particular drug (but not flucloxacillin or amoxicillin-clavulanate). We used DNA samples from all subjects to analyze HLA genes and single nucleotide polymorphisms. After the discovery analysis was concluded, we validated our findings using data from 283 European patients with diagnosis of DILI associated with various drugs. RESULTS: We associated DILI with rs114577328 (a proxy for A* 33: 01 a HLA class I allele; odds ratio [OR], 2.7; 95% confidence interval [CI], 1.9 - 3.8; P = 2.4 x 10(-8)) and with rs72631567 on chromosome 2 (OR, 2.0; 95% CI, 1.6 - 2.5; P = 9.7 x 10(-9)). The association with A* 33: 01 was mediated by large effects for terbinafine-, fenofibrate-, and ticlopidine-related DILI. The variant on chromosome 2 was associated with DILI from a variety of drugs. Further phenotypic analysis indicated that the association between DILI and A* 33: 01 was significant genome wide for cholestatic and mixed DILI, but not for hepatocellular DILI; the polymorphism on chromosome 2 was associated with cholestatic and mixed DILI as well as hepatocellular DILI. We identified an association between rs28521457 (within the lipopolysaccharide-responsive vesicle trafficking, beach and anchor containing gene) and only hepatocellular DILI (OR, 2.1; 95% CI, 1.6 - 2.7; P = 4.8 x 10(-9)). We did not associate any specific drug classes with genetic polymorphisms, except for statin-associated DILI, which was associated with rs116561224 on chromosome 18 (OR, 5.4; 95% CI, 3.0 - 9.5; P = 7.1 x 10(-9)). We validated the association between A* 33: 01 terbinafine-and sertraline-induced DILI. We could not validate the association between DILI and rs72631567, rs28521457, or rs116561224. CONCLUSIONS: In a GWAS of persons of European descent with DILI, we associated HLA-A* 33: 01 with DILI due to terbinafine and possibly fenofibrate and ticlopidine. We identified polymorphisms that appear to be associated with DILI from statins, as well as 2 non-drug-specific risk factors.
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| 47. |
- Olsson, Rickard, et al.
(författare)
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Challenges to the interpretation of the electromagnetic feedback from laser welding
- 2011
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Ingår i: Optics and lasers in engineering. - : Elsevier BV. - 0143-8166 .- 1873-0302. ; 49:2, s. 188-194
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers the point that it is not possible to interpret individual weld perturbations from the raw electromagnetic feedback collected from laser weld zones. The presentation of electromagnetic data as a 3D cloud is presented as a new, useful tool in the analysis of this feedback. It is shown that there is a very low correlation between the plasma or thermal signals and the reflected light signal from the weld zone, and that a strong correlation exists between the plasma and thermal signals. It is also demonstrated that data points from a weld perturbation form a different 3D cluster to those from the stable welding process. A strategy for future real time data analysis is presented utilising a suitably shaped data cloud envelope. The rates of data fit to the various segments of such an envelope could be correlated with specific weld anomalies.
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| 48. |
- Olsson, Rickard, 1959-, et al.
(författare)
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Normal vector distribution as a classification tool for convoluted rough surfaces with overhanging features
- 2020
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Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 32:2
-
Tidskriftsartikel (refereegranskat)abstract
- Convoluted rough surfaces involving overhanging features can be a natural consequence of laser additive manufacturing and other spray techniques or can be generated deliberately by laser surface texturing, e.g., to aid osseointegration. Overhanging features add an extra level of complexity to the topography of a rough surface and can have a substantial effect on wettability, etc. However, features of this type are invisible to traditional surface roughness measurement techniques. This work presents a computer-based surface analysis method that gives useful information about the presence and nature of overhanging features on rough technical surfaces. The technique uses micro-computer tomography to generate a typical cross section of the surface under investigation. The angles of the vectors normal to the surface can then be analyzed to reveal the presence of overhanging features, which can also be indicated by the standard deviation of the normal vector distribution. Titanium surfaces generated by six different techniques were compared. The characteristics of these surfaces varied strongly, as did the shapes of the overhangs involved. These variations are reflected by different statistical distributions of the normal vectors.
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| 49. |
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| 50. |
- Olsson, Rickard, 1959-, et al.
(författare)
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Topographical evaluation of laser generated surfaces using statistical analysis of surface-normal vector distributions
- 2021
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Ingår i: IOP Conference Series: Materials Science and Engineering. - : Institute of Physics (IOP).
-
Konferensbidrag (refereegranskat)abstract
- Surfaces generated by Additive Manufacturing or laser texturing can involve the solidification of droplets of liquid, which can give rise to overhanging features on the solidified surface. Overhanging features add a layer of complexity to the surface topography and are undetectable by standard surface roughness measurement techniques such as profilometry. Such features are important because they can have a considerable effect on surface properties such as wettability. New techniques and algorithms are therefore required to analyse and quantify convoluted surfaces with overhanging (re-entrant) features. Earlier work by the authors introduced the concept of using X-ray micro-computed tomography (Micro-CT) to identify the directions of vectors normal to the surface at any point and thus indicate the presence or absence of overhanging features. This paper divides overhanging features into two types; simple and compound, and introduces new, size independent, analysis techniques which measure what proportion of each type is on the surface. Another extension of the analysis is the comparison of surface profiles taken in different directions in order to identify any surface roughness anisotropies.
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