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- Vilardell, Anna M., et al.
(författare)
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Manufacturing and characterization of in-situ alloyed Ti6Al4V(ELI)-3 at.% Cu by laser powder bed fusion
- 2020
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Ingår i: Additive Manufacturing. - : Elsevier. - 2214-8604 .- 2214-7810. ; 36, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Biofunctionalization of Ti6Al4V alloy with metallic agents like Ag or Cu is a promising approach to add antibacterial properties and thus to reduce the risk of implant failure. This research investigates the in-situ alloying of Ti6Al4V(ELI) with 3 at.% Cu powders using Laser Powder Bed Fusion (L-PBF). The morphology and geometrical characteristics of the single tracks and layers were studied. Laser powers of 170 W and 340 W, and scanning speeds ranging from 0.4 to 1.4 m/s and 0.8-2.8 m/s were implemented. Single track results showed balling effect and humping at high scanning speeds, 1.4 m/s and 1.6 m/s, for each laser powder respectively. Conversely, keyhole formation occurred at lower scanning speeds of 0.4-0.6 m/s for 170 W laser power, and below and 0.8 m/s for 340 W laser power. For both laser powers, single layers resulted in smoother surfaces at lower scanning speeds. These results were used for the development of optimal process parameters for 3D cubes with 99.9 % density. Optimal process parameters were found for 170 W and 340W laser powders at 0.7-0.9 and 1.0-1.2 m/s scanning speeds, respectively.In-situ alloying by L-PBF was challenging and a homogeneous distribution of Cu within the alloy was hard to achieve. The increase in laser power from 170 to 340 W resulted in small increase in homogenization. Microstructural analyses after stress-relieving treatment showed the presence of alpha' and beta phases, as well as CuTi2 intermetallic precipitates. The finer microstructure together with CuTi2 intermetallic precipitates resulted in an increase in hardness. This study demonstrates the potential for printing in-situ alloyed Ti6Al4V(ELI)- 3 at.% Cu for biomedical applications. However, further studies are required to determine the effectiveness of antibacterial properties.
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| 3. |
- Vilardell, Anna M., et al.
(författare)
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Mechanical behavior of in-situ alloyed Ti6Al4V(ELI)-3 at.% Cu lattice structures manufactured by laser powder bed fusion and designed for implant applications
- 2021
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Ingår i: Journal of The Mechanical Behavior of Biomedical Materials. - : Elsevier. - 1751-6161 .- 1878-0180. ; 113, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, cellular lattice structures for implant applications are reported for the first-time incorporating copper directly by in-situ alloying in the laser powder bed fusion process. The aim to incorporate 3 at.% Cu into Ti6Al4V(ELI) is selected for improved antibacterial properties while maintaining appropriate mechanical properties. Previously, topologically optimized Ti6Al4V(ELI) lattice structures were successfully designed, manufactured and studied for implant applications. The development of a new alloy produced by in-situ alloying of elemental powder mixture of Ti6Al4V(ELI) and pure Cu powders was used here for the production of identical lattice structures with improved antibacterial properties. One of the same as-designed CAD models was used for the manufacturing of these lattices compared to previous work on pure Ti6Al4V(ELI) lattices, making direct comparison of mechanical properties possible. Similar manufacturability highlights the applicability of this alloying technique to other lattice designs. Microstructural characterization was performed by optical and electron microscopies, as well as microCT. Mechanical characterization was performed by means of compression tests and hardness measurements. Results showed that in-situ alloying with copper leads to the formation of localized Cu-rich regions, refinement of martensitic phase and the formation of CuTi2 intermetallic precipitates, which increased the hardness and strength of the material. Deviations in wall thickness between the as-designed and as-manufactured lattices led to anisotropy of the mechanical properties of the lattices. Higher compressive strength values were obtained when thicker walls were oriented along the loading direction. Nevertheless, alloying with Cu had a higher impact on the compressive strength of lattice structure than the wall thickness deviations. The direct in-situ alloying of copper in Ti6Al4V(ELI) is a promising mute for direct manufacturing of antibacterial implants.
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- Redondo-Camos, M., et al.
(författare)
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Local Prefrontal Cortex TMS-Induced Reactivity Is Related to Working Memory and Reasoning in Middle-Aged Adults
- 2022
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Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionThe prefrontal cortex (PFC) plays a crucial role in cognition, particularly in executive functions. Cortical reactivity measured with Transcranial Magnetic Stimulation combined with Electroencephalography (TMS-EEG) is altered in pathological conditions, and it may also be a marker of cognitive status in middle-aged adults. In this study, we investigated the associations between cognitive measures and TMS evoked EEG reactivity and explored whether the effects of this relationship were related to neurofilament light chain levels (NfL), a marker of neuroaxonal damage. MethodsFifty two healthy middle-aged adults (41-65 years) from the Barcelona Brain Health Initiative cohort underwent TMS-EEG, a comprehensive neuropsychological assessment, and a blood test for NfL levels. Global and Local Mean-Field Power (GMFP/LMFP), two measures of cortical reactivity, were quantified after left prefrontal cortex (L-PFC) stimulation, and cognition was set as the outcome of the regression analysis. The left inferior parietal lobe (L-IPL) was used as a control stimulation condition. ResultsLocal reactivity was significantly associated with working memory and reasoning only after L-PFC stimulation. No associations were found between NfL and cognition. These specific associations were independent of the status of neuroaxonal damage indexed by the NfL biomarker and remained after adjusting for age, biological sex, and education. ConclusionOur results demonstrate that TMS evoked EEG reactivity at the L-PFC, but not the L-IPL, is related to the cognitive status of middle-aged individuals and independent of NfL levels, and may become a valuable biomarker of frontal lobe-associated cognitive function.
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- Vork, L., et al.
(författare)
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Development, content validity, and cross-cultural adaptation of a patient-reported outcome measure for real-time symptom assessment in irritable bowel syndrome
- 2018
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Ingår i: Neurogastroenterology and Motility. - : Wiley. - 1350-1925. ; 30:3
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundEnd-of-day questionnaires, which are considered the gold standard for assessing abdominal pain and other gastrointestinal (GI) symptoms in irritable bowel syndrome (IBS), are influenced by recall and ecological bias. The experience sampling method (ESM) is characterized by random and repeated assessments in the natural state and environment of a subject, and herewith overcomes these limitations. This report describes the development of a patient-reported outcome measure (PROM) based on the ESM principle, taking into account content validity and cross-cultural adaptation. MethodsFocus group interviews with IBS patients and expert meetings with international experts in the fields of neurogastroenterology & motility and pain were performed in order to select the items for the PROM. Forward-and-back translation and cognitive interviews were performed to adapt the instrument for the use in different countries and to assure on patients' understanding with the final items. Key resultsFocus group interviews revealed 42 items, categorized into five domains: physical status, defecation, mood and psychological factors, context and environment, and nutrition and drug use. Experts reduced the number of items to 32 and cognitive interviewing after translation resulted in a few slight adjustments regarding linguistic issues, but not regarding content of the items. Conclusions and InferencesAn ESM-based PROM, suitable for momentary assessment of IBS symptom patterns was developed, taking into account content validity and cross-cultural adaptation. This PROM will be implemented in a specifically designed smartphone application and further validation in a multicenter setting will follow.
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| 6. |
- Lambert, SA, et al.
(författare)
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The Human Transcription Factors
- 2018
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Ingår i: Cell. - : Elsevier BV. - 1097-4172 .- 0092-8674. ; 172:4, s. 650-665
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Lambert, SA, et al.
(författare)
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The Human Transcription Factors
- 2018
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Ingår i: Cell. - : Elsevier BV. - 1097-4172 .- 0092-8674. ; 175:2, s. 598-599
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Vilardell, Anna M., et al.
(författare)
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Effect of Heat Treatment on Osteoblast Performance and Bactericidal Behavior of Ti6Al4V(ELI)-3at.%Cu Fabricated by Laser Powder Bed Fusion
- 2023
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Ingår i: Journal of Functional Biomaterials. - : MDPI. - 2079-4983. ; 14:2
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Tidskriftsartikel (refereegranskat)abstract
- Cu addition to alloys for biomedical applications has been of great interest to reduce bacterial growth. In situ-alloyed Ti6Al4V(ELI)-3at.%Cu was successfully manufactured by laser powder bed fusion (L-PBF). Even so, post-heat treatments are required to avoid distortions and/or achieve required/desired mechanical and fatigue properties. The present study is focused on the investigation of microstructural changes in L-PBF Ti6Al4V(ELI)-3at.%Cu after stress relieving and annealing treatments, as well as their influence on osteoblast and bactericidal behavior. After the stress relieving treatment, a homogenously distributed β phase and CuTi2 intermetallic precipitates were observed over the αʹ matrix. The annealing treatment led to the increase in amount and size of both types of precipitates, but also to phase redistribution along α lamellas. Although microstructural changes were not statistically significant, such increase in β and CuTi2 content resulted in an increase in osteoblast proliferation after 14 days of cell culture. A significant bactericidal behavior of L-PBF Ti6Al4V(ELI)-3at.%Cu by means of ion release was found after the annealing treatment, provably due to the easier release of Cu ions from β phase. Biofilm formation was inhibited in all on Cu-alloyed specimens with stress relieving but also annealing treatment.
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