Publikationer från Uppsala Universitet
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From Phenolated Lignin to Few-Layered Graphene : Laser-Induced Carbonization for Micro-Supercapacitor Application
No full textThis study explores the potential of phenolated lignin as a precursor for synthesizing graphene-like carbon materials through laser-induced carbonization (LIC). Key parameters─including formulation, laser speed, laser power, and lignin loading─were optimized to enhance the quality of the resulting LIC materials. Under optimized conditions, this method produced a high-quality, few-layer graphene-like carbon material. Comprehensive materials characterization (XPS, XRD, TGA, Raman spectroscopy, sheet resistivity, and elemental analysis) revealed that the material’s conductivity is driven by the formation of an sp2-hybridized conjugated carbon system and the reduction of both sp3-hybridized carbon and oxygen groups. The introduction of phenolic groups into the lignin structure enhanced its thermostability and conversion efficiency to graphene-like carbon, achieving a low sheet resistance of 6.7 Ω·sq–1. This study demonstrates that phenolated lignin is a promising precursor for the synthesis of conductive graphene-like carbon materials with excellent electronic properties, making it suitable for micro-supercapacitor applications. Furthermore, the resulting printed device exhibited a specific capacitance of 454 mF cm–3 (1.4 mF cm–2) at a scan rate of 5 mV s–1 in cyclic voltammetry (CV) mode and 286 mF cm–3 (0.86 mF cm–2) at a current density of 0.05 mA cm–2 in galvanostatic charge–discharge (GCD) mode
Molecular epidemiology of extended-spectrum beta-lactamase producing Gram-negative bacteria among surgical site infection patients in Ethiopia : a multicenter prospective study
No full textExtended-spectrum beta-lactamases (ESBLs) producing Gram-negative bacteria are public health threats. This study aims to characterize ESBL-producing Gram-negative bacteria (GNB) isolated from surgical site infection patients. A multicenter cross-sectional study was conducted at four hospitals located in central (Addis Ababa), southern (Hawassa), northern (Debre Tabor), and Southwestern (Jimma) parts of Ethiopia. A wound culture was performed among 752 surgical site infection (SSI) patients where 286 GNB were confirmed using MALDI-TOF; of which 135 were subjected to whole genome sequencing using the Illumina (HiSeq 2500) system. The overall genotypic frequencies of ESBL-producing GNB were 57.8%. The detection of ESBL-producing GNB at Hawassa, Debre Tabor, Jimma, and Addis Ababa was 21.5%, 19.3%, 29.6%, and 29.6%, respectively. The detection frequency of blaCTX−M, blaTEM, and blaSHV genes was 51.8%, 40%, and 8.1%, respectively. The most frequently detected ESBL gene was blaCTX−M−15 (56.4%). Both blaTEM−1B (41%) and blaSHV−187 (5.1%) were the most frequently detected variants of blaTEM and blaSHV, respectively. The molecular epidemiology of ESBL-producing GNB among surgical site infection patients in Ethiopia showed many variants of ESBL genes. Good antimicrobial stewardship and standard bacteriological laboratory services are necessary for the effective treatment of ESBL-producing GNB
Global longitudinal strain in long-term risk prediction after acute coronary syndrome : an investigation of added prognostic value to ejection fraction
No full textAIMS: This study aimed to investigate the additional value of global longitudinal strain (GLS) on top of left ventricular ejection fraction (LVEF) in long-term risk prediction of combined death and heart failure (HF) re-hospitalization after acute coronary syndrome (ACS). METHOD AND RESULTS: This retrospective study included patients admitted with ACS between 2008 and 2014 from the three participating university hospitals. LVEF and GLS were assessed at a core lab from images acquired during the index hospital stay. Their prognostic value was studied with the Cox proportional hazards model (median follow-up 6.2 years). A nested model comparison was performed with C-statistics. A total of 941 patients qualified for multivariable analysis after multiple imputation of missing baseline covariables. The combined outcome was reached in 17.7% of the cases. Both GLS and LVEF were independent predictors of the combined outcome, hazard ratio (HR) 1.068 (95% CI 1.017-1.121) and HR 0.980 (95% CI 0.962-0.998), respectively. The C-statistic increased from 0.742 (95% CI 0.702-0.783) to 0.749 (95% CI 0.709-0.789) (P = 0.693) when GLS entered the model with clinical data and LVEF. CONCLUSION: GLS emerged as an independent long-term risk predictor of all-cause death and HF re-hospitalization. However, there was no significant incremental predictive value of GLS when LVEF was already known
Ultrathin AlOx Films for Back Contact Passivation in Bifacial Wide‐Gap (Ag,Cu)(In,Ga)Se2 Solar Cells
No full textThis work studies the thickness effect of atomic-layer-deposited AlOx films, acting as back contact passivation layers in bifacial, wide-bandgap (EG = 1.4–1.5 eV) (Ag,Cu)(In,Ga)Se2 (ACIGS) solar cells with In2O3:W transparent rear electrodes. For each tested AlOx thickness (1.0, 2.0, and 3.5 nm), several absorber-deposition runs, with varying ACIGS thicknesses, were conducted. It is found that a 3.5 nm-thick AlOx layer results in strongly impeded hole extraction and thus, severe losses in short-circuit current. As a consequence, carrier collection at front and rear illumination is inferior to reference devices without AlOx, independent of the absorber thickness. Reducing the AlOx thickness to 2.0 nm still results in fill factor losses, but the collection of electrons generated close to the back contact can be improved. Finally, 1.0 nm of AlOx only leads to a minor barrier for carrier transport, but the passivating character vanishes. The experiments confirm that sufficiently thick AlOx films (≥ 2 nm) can reduce the back contact recombination rate in bifacial wide-gap ACIGS solar cells. However, in order to improve the efficiency at rear illumination, those films need to be locally opened to allow for adequate carrier flow
The Court's Obligation to Adhere to the Description of the Offence in the Presence of Surplus Allegations
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Antifragility in IT-projects : How risks and uncertainties can be dealt with in a complex world
No full textThe managing of risks in projects is becoming increasingly harder in the modern world because of increased complexity. IT projects are subject to extreme cost overruns and failures because of risks and dependencies that impact the successful completion of them. The purpose of this study is to study how the handling of risks and uncertainties in IT projects relate to the concept of antifragility. Six project members from Swedish companies have been interviewed to find out how they think about risks and how they handle them. The data was analysed with a framework for antifragility in projects to see how the antifragile concepts relate to the risk management in IT projects. The results show that there exists a lot of risks related to IT projects, mainly concerning lack of communication, flexibility and ability to adapt, and that antifragile concepts can be used to better look at the handling of risks and uncertainties in IT projects
När förskolebarn berättar sagor : Hur gör de då? Vilka sagor berättas?
No full textThis master's thesis examines how five-year-old children in two Swedish preschools use verbal language in combination with bodily expressions when telling a story with the support of artifacts. The preschool's educational mission regarding language development and the preschool teacher's responsibility as outlined in the national curriculum, as well as a previous study conducted by the author on reading aloud as a teaching method, provide contextual background. The literature review discusses previous research on narrative research, teaching in preschool, oral storytelling, reading aloud, and the role of play and creativity. The theoretical framework is based on social constructivism and social semiotics, with references to Vygotsky's theory of play and creativity as well as systemic functional linguistics. The study uses qualitative methods such as participant observation and semi-structured interviews conducted at two selected preschools. Data were analyzed through thematic analysis and text analysis. The results are presented thematically in categories where the text analysis offer further depth within each category. The results show that the children's stories, both well-known and invented, reflect previous experiences of reading aloud and storytelling and that the use of artifacts and narrative structures varies between categories. All stories matched the readability levels for early children's literature. Finally, the results are discussed in relation to the research questions, the theoretical starting points and previous observation of reading aloud as a teaching method. This study can contribute to the field of research by helping us understand how oral storytelling can be used as a teaching method to support children´s emergent literacy development