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- Dekov, V.M., et al.
(författare)
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Mineralogy, geochemistry and microbiology insights into precipitation of stibnite and orpiment at the Daiyon-Yonaguni Knoll (Okinawa Trough) hydrothermal barite deposits
- 2022
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Ingår i: Chemical Geology. - Amsterdam : Elsevier. - 0009-2541 .- 1872-6836. ; 610, s. 121092-121092
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Tidskriftsartikel (refereegranskat)abstract
- Samples of active chimneys, chimney flanges and massive sulfides from the Daiyon-Yonaguni Knoll hydrothermal field are composed of major barite and minor stibnite and orpiment. Barite is inferred to precipitate from focused-discharge fluids composed of >40% hydrothermal end-member fluid at T = 100-240°C, whereas the stibnite and orpiment are later and lower temperature precipitates. The hydrothermal fluids from this field were subject of sub-seafloor boiling and phase separation and, consequently, are brine-rich depleted in volatile and enriched in non-volatile elements. Boiling and phase separation exerted major control on the rare earth elements (REE) partitioning in the vent fluids: high-chlorinity high-temperature fluids were enriched in light REE and low-chlorinity low-temperature fluids were enriched in heavy REE. Y/Ho molar ratio and Ce anomaly of the vent fluids suggest that the seawater has not completely reacted with the basement rocks and has not equilibrated with them. The trace element concentrations in the hydrothermal deposits suggest a complex interplay among hydrothermal, hydrogenetic and microbial processes. Sulfur isotope composition of the sulfides suggests that the sulfide S is a mixture of both basement rock and seawater S with a higher proportion of the basement rock S. The sulfate dissolved in the fluids was subjected to reduction during a slow mixing of hydrothermal fluid and seawater within the chimney walls of the Tiger and Abyss vents and this resulted in a heavy S-isotope composition of the vent fluid sulfate. Lead isotope composition of the hydrothermal deposits indicates mixing relationships suggesting that Pb and potentially other metals with similar geochemical behavior were derived from two or three sources. The Pb isotopes in the hydrothermal deposits imply that an enriched source, either sediments or extended continental lithosphere, and a depleted source, potentially back-arc mafic volcanics, are present in the area of Daiyon-Yonaguni Knoll. Filamentous orpiment found in the deposits is supposed to be either heavily mineralized fungal hyphae or pure abiogenic biomorphs. Presence of carbonaceous matter on and around the orpiment filaments suggests for microbial activity during filament formation. The filaments experienced temperature of 209.1±37.1°C which falls within the temperature range of the Daiyon-Yonaguni Knoll vent fluids. Stability phase diagrams modeling reveals that the stability of stibnite does not depend on the vent fluid chlorinity, but depends on the vent fluid temperature: the area of stibnite stability increases with decreasing vent fluid temperature and results in stibnite precipitation at low log10a of Sb2S42- and less reduced environment (Eh still <0). Orpiment is stable in a wide range of log10a of H2AsO4-, in reduced conditions and at high S activity. Barite is stable in wide range of log10a of Ba2+ and precipitates in slightly reduced to slightly oxic conditions.
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- Gabriel, R., et al.
(författare)
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Reduction in the Risk of Peripheral Neuropathy and Lower Decrease in Kidney Function with Metformin, Linagliptin or Their Fixed-Dose Combination Compared to Placebo in Prediabetes: A Randomized Controlled Trial
- 2023
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Ingår i: Journal of Clinical Medicine. - : MDPI AG. - 2077-0383. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To compare the effect of glucose-lowering drugs on peripheral nerve and kidney function in prediabetes. Methods: Multicenter, randomized, placebo-controlled trial in 658 adults with prediabetes treated for 1 year with metformin, linagliptin, their combination or placebo. Endpoints are small fiber peripheral neuropathy (SFPN) risk estimated by foot electrochemical skin conductance (FESC < 70 mu Siemens) and estimated glomerular filtration rate (eGFR). Results: Compared to the placebo, the proportion of SFPN was reduced by 25.1% (95% CI:16.3-33.9) with metformin alone, by 17.3% (95% CI 7.4-27.2) with linagliptin alone, and by 19.5% (95% CI 10.1-29.0) with the combination linagliptin/metformin (p < 0.0001 for all comparisons). eGFR remained +3.3 mL/min (95% CI: 0.38-6.22) higher with the combination linagliptin/metformin than with the placebo (p = 0.03). Fasting plasma glucose (FPG) decreased more with metformin monotherapy -0.3 mmol/L (95%CI: -0.48; 0.12, p = 0.0009) and with the combination metformin/linagliptin -0.2 mmol/L (95% CI: -0.37; -0.03) than with the placebo (p = 0.0219). Body weight (BW) decreased by -2.0 kg (95% CI: -5.65; -1.65, p = 0.0006) with metformin monotherapy, and by -1.9 kg (95% CI: -3.02; -0.97) with the combination metformin/linagliptin as compared to the placebo (p = 0.0002). Conclusions: in people with prediabetes, a 1 year treatment with metformin and linagliptin, combined or in monotherapy, was associated with a lower risk of SFPN, and with a lower decrease in eGFR, than treatment with placebo.
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- Haralanova, Valentina, et al.
(författare)
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Challenges in Training on Engineering Graphics - Experiences from Two European Universities
- 2018
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Ingår i: EDULEARN18. - : The International Academy of Technology, Education and Development. - 9788409027095 ; , s. 7502-7512
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Konferensbidrag (refereegranskat)abstract
- In the presented publication the authors reflect on their long-term teaching experiences in the field of Applied geometry and Engineering graphics accumulated at two European universities - Ruse University, Bulgaria and Linnaeus University, Sweden. The main problems and challenges in the training of students of the engineering specialties of the two universities in disciplines related to descriptive geometry, technical drawing, engineering graphics and 2D and 3D CAD, are related to an establishment of practical skills for execution of different types of drawings, to the building up a spatial vision for faster and more efficient reading and implementing of drawings and an accumulation of sufficient knowledge and information on the current standards in the field of engineering graphics and technical documentation. Graphics and visualization are a preferred form of communication in engineering practices and engineering education. Various methods of descriptive geometry and computer graphics are applied in order to achieve an effective visualization. By using technical standards for defining the practical usage of symbols, graphical elements and units of measurement, a visual language is created that assists and ensures a transmission of unambiguous, clear and understandable information. The publication presents a review of approaches and training methods applied at both universities over the past 10 years, and a comparison of the results achieved. Finally, conclusions are drawn, how having in consideration others and their own experiences and taking into account some recent trends in the work of designers, developers and technologists, the students' learning outcomes of in their preparation for future engineers could be improved.
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- Picca, Anna, et al.
(författare)
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Altered Expression of Mitoferrin and Frataxin, Larger Labile Iron Pool and Greater Mitochondrial DNA Damage in the Skeletal Muscle of Older Adults
- 2020
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Ingår i: Cells. - : MDPI AG. - 2073-4409. ; 9:12
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondrial dysfunction and iron (Fe) dyshomeostasis are invoked among the mechanisms contributing to muscle aging, possibly via a detrimental mitochondrial-iron feed-forward loop. We quantified the labile Fe pool, Fe isotopes, and the expression of mitochondrial Fe handling proteins in muscle biopsies obtained from young and older adults. The expression of key proteins of mitochondrial quality control (MQC) and the abundance of the mitochondrial DNA common deletion (mtDNA(4977)) were also assessed. An inverse association was found between total Fe and the heavier Fe isotope (Fe-56), indicating an increase in labile Fe abundance in cells with greater Fe content. The highest levels of labile Fe were detected in old participants with a Short Physical Performance Battery (SPPB) score <= 7 (low-functioning, LF). Protein levels of mitoferrin and frataxin were, respectively, higher and lower in the LF group relative to young participants and older adults with SPPB scores >= 11 (high-functioning, HF). The mtDNA(4977) relative abundance was greater in old than in young participants, regardless of SPPB category. Higher protein levels of Pink1 were detected in LF participants compared with young and HF groups. Finally, the ratio between lipidated and non-lipidated microtubule-associated protein 1A/1B-light chain 3 (i.e., LC3B II/I), as well as p62 protein expression was lower in old participants regardless of SPPB scores. Our findings indicate that cellular and mitochondrial Fe homeostasis is perturbed in the aged muscle (especially in LF older adults), as reflected by altered levels of mitoferrin and frataxin, which, together with MQC derangements, might contribute to loss of mtDNA stability.
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