Publikationer från Uppsala Universitet
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CAU-52 : An Iron Metal-Organic Framework Containing Furandicarboxylate Linker Molecules
No full textThe V-shaped linker molecule 2,5-furandicarboxylic acid (H2FDC), which can be derived from lignocellulosic biomass, was used in a systematic screening with various iron salts and led to the discovery of a new iron-based metal–organic framework (Fe-MOF) with the composition [Fe3(μ3-O)(FDC)3(OH)(H2O)2]·5H2O·H2FDC, designated as CAU-52 (CAU = Christian-Albrechts-Universität zu Kiel). The crystal structure of CAU-52 was determined using 3D electron diffraction (3D ED) and further refined by Rietveld refinement against powder X-ray diffraction (PXRD) data. CAU-52 contains the well-known trinuclear [Fe3(μ3-O)]7+ cluster as the inorganic building unit (IBU) that is six-connected by FDC2– ions to form the pcu net. The connectivity leads to two types of cubic cages, similar to the ones observed in soc-MOFs. Comprehensive characterization of the title compound, including N2 and water vapor sorption measurements, confirmed its chemical composition. CAU-52 exhibits microporosity toward nitrogen with a type-I isotherm (77 K), yielding a specific surface area of as,BET = 1077 m2/g. The H2O sorption measurement at 298 K leads to an isotherm that exhibits three steps. The water sorption capacity was determined to be 390 mg/g, and it decreases slightly in subsequent sorption cycles. The MOF is stable up to 250 °C in air and chemically resistant in various solvents
Control of ferrimagnetic compensation and perpendicular anisotropy in TbCo(100−) with H+ ion implantation
No full textThe tuning of magnetic properties through electrochemical loading of hydrogen has recently attracted significant interest as a way to manipulate magnetic devices with electric fields. In this paper we investigate quantitatively the magneto-ionic effect of hydrogen uptake on the magnetic properties of rare-earth transition-metal alloy TbxCo(100-x) in the composition range of x = 10-39 at.% using ion implantation. Using this technique we are able to link changes in magnetic behavior to exact concentrations of hydrogen, isolated from the movement of any other ions that would be a factor in electrochemical studies. The composition of the alloy has been varied alongside the hydrogen dose to characterize the effect of progressive hydrogen loading on the full range of x displaying out-of-plane magnetic anisotropy. We find large changes in two important properties: the compensation composition and the Co-rich in-plane to out-of-plane magnetic anisotropy transition composition, both of which move by 6 at.% toward higher Tb concentrations after hydrogen implantation. This shift in composition does not increase with a larger dose. From the changes in magnetization we attribute the change in compensation composition to a significant reduction of the moment on the Tb sublattice
Minimizing Questionable Research Practices : The Role of Norms, Counter Norms, and Micro-Organizational Ethics Discussion
No full textBreaches of research integrity have gained considerable attention due to high-profile scandals involving questionable research practices by reputable scientists. These practices include plagiarism, manipulation of authorship, biased presentation of findings and misleading reports of significance. To combat such practices, policymakers tend to rely on top-down measures, mandatory ethics training and stricter regulation, despite limited evidence of their effectiveness. In this study, we investigate the occurrence and underlying factors of questionable research practices (QRPs) through an original survey of 3,005 social and medical researchers at Swedish universities. By comparing the role of the organizational culture, researchers ' norms and counter norms, and individual motivation, the study reveals that the counter norm of Biasedness-the opposite of universalism and skepticism-is the overall most important factor. Thus, Biasedness was related to 40-60% of the prevalence of the questionable practices. The analysis also reveals the contradictory impact of other elements in the organizational environment. Internal competition was positively associated with QRP prevalence, while group-level ethics discussions consistently displayed a negative association with such practices. Furthermore, in the present study items covering ethics training and policies have only a marginal impact on the prevalence of these practices. The organizational climate and normative environment have a far greater influence. Based on these findings, it is suggested that academic leaders should prioritize the creation and maintenance of an open and unbiased research environment, foster a collaborative and collegial climate, and promote bottom-up ethics discussions within and between research groups
Recent updates in the VERDI fission-fragment spectrometer
No full textThe VElocity foR Direct particle Identification (VERDI) is a spectrometer designed to determine fission-fragment mass distributions using the 2E-2v method, which measures both velocities and energies of the fission fragments. VERDI has two time-of-flight (TOF) sections, each with a Micro Channel Plate (MCP) Time-of-flight Start detector and up to 32 passivated implanted planar silicon (PIPS) detectors. Achieving the desired mass resolution is challenged by the need for high TOF and energy resolutions. Recent upgrades to the VERDI setup have improved its performance, achieving a TOF resolution as low as 355 ps (FWHM) and an energy resolution of 22 keV (FWHM) for alpha-particles. These enhancements in resolution demonstrate improved capabilities for achieving high-precision fission fragment yield measurements
Speech perception and hearing preservation after cochlear implantation in patients with Meniere's disease
No full textIntroduction Cochlear implantation can be used as a treatment for severe sensorineural hearing loss in patients with Meniere’s disease. Aim The aim of the present study was to investigate speech perception and the grade of hearing preservation in patients diagnosed with Meniere’s disease. One additional aim was to investigate the effects of cochlear implant surgery on balance and tinnitus. Methods Adult patients with a known diagnosis of Meniere’s disease were evaluated. Their speech perception and the degree of hearing preservation were compared with adult patients with sensorineural hearing loss of different etiologies. For the patients with Meniere’s disease, their subjective reports on balance and tinnitus pre- and post-surgery were also investigated. Results Both groups showed a statistically significant improvement in speech perception after cochlear implantation (p < .05); no statistically significant difference was found between the two groups. Analysis of hearing preservation for the two groups showed no statistically significant difference. Tinnitus decreased in 44.4% of the Meniere’s disease patients one year post surgery. Conclusion We found no difference in speech perception with cochlear implant in patients with Meniere’s disease compared with patients with other etiologies, and there was no difference in the rate of hearing preservation. Tinnitus improved after cochlear implant treatment in patients with Meniere’s diseas
Mapping effective microRNA pairing beyond the seed using abasic modifications
No full textMicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression by base-pairing to complementary sites in messenger RNAs (mRNAs). The primary element for site recognition is the seed region (nucleotides 2-8 in the miRNA), but for a minority of sites pairing outside the seed increases efficiency, with the supplementary region (nucleotides 13-16) typically having the greatest impact. However, the structural determinants of effective pairing outside the seed are not fully understood. Here, we use abasic modified nucleotides to disrupt pairing to residues 13 and 14 of miR-34a and measure the effect of this modification compared to wild-type miR-34a on the cellular transcriptome and proteome using RNA-seq and mass spectrometry. We find that a subset of sites with predicted supplementary pairing are affected by miRNA transfection, with up to two-fold decreases in site repression at the mRNA level. We show that miR-34a 3'-pairing is sensitive to GU wobble pairs in a position-specific manner and favors bulges in the miRNA over the target. These results were validated with luciferase reporter assays. Overall, this study demonstrates a novel methodological approach for elucidating the role of specific miRNA residues in target site selection, advancing our understanding of miRNA-mediated gene regulation
Virtual Fragment Screening for DNA Repair Inhibitors in Vast Chemical Space
No full textFragment-based screening can catalyze drug discovery by identifying novel scaffolds, but this approach is limited by the small chemical libraries studied by biophysical experiments and the challenging hit optimization step. In efforts to identify DNA repair inhibitors, we explored the use of structure-based virtual screening to access ultralarge fragment libraries that cover four orders of magnitude larger fractions of chemical space than traditional techniques. A set of 14 million fragments were docked to 8-oxoguanine DNA glycosylase (OGG1), a challenging drug target involved in cancer and inflammation. Of the 29 top-ranked fragments that were experimentally evaluated, four compounds were shown to bind to OGG1 and X-ray crystallography confirmed the predicted binding modes. Docking of readily synthesizable elaborations guided fragment optimization, leading to the discovery of submicromolar OGG1 inhibitors with anti-inflammatory and anti-cancer effects in cell models. Our results demonstrate that fragment-based virtual screening enables efficient exploration of vast chemical libraries
Vulnerabilities in Ethereum Smart Contracts : An Analysis of Testing and Verification Techniques
No full textThis bachelor’s thesis investigates the critical need for robust testing and verification techniques for smart contracts, which play a key role in blockchain ecosystems. Despite previous advances in tool development and vulnerability identification, consistent benchmarking for evaluating tool effectiveness remains limited. This study builds on existing research by systematically analyzing current methodologies and proposing recommendations to strengthen smart contract security. The investigation begins with an overview of smart contract architecture and their inherent vulnerabilities, particularly those stemming from properties such as immutability, decentralization, and autonomous execution, which hinder post-deployment error correction. The thesis evaluates a range of testing and verification approaches, including fuzzing, symbolic execution, systematic modeling, and machine learning-based methods. In addition, it assesses the effectiveness of selected analysis tools in real-world scenarios using a defined set of benchmarking criteria, focusing on detection accuracy, resource efficiency, and code coverage. The findings comprise a categorized overview of common vulnerabilities, an empirical evaluation of prominent tools, and actionable recommendations for improving testing practices. By introducing practical benchmarks and insights, this research contributes to the development of more reliable smart contracts and supports the advancement of secure blockchain infrastructures.
Factors Influencing General Practitioners' Deprescribing Decisions for Older Adults, with Insights into Frailty : a Qualitative Study in Greek Primary Care
No full textIntroduction: Polypharmacy is increasing among older individuals worldwide. Deprescribing has been suggested as a strategy to reduce polypharmacy, but it has had a limited impact. Objective: This study investigated the facilitators and barriers to deprescribing in older adults, as perceived by primary care general practitioners, focusing particularly on factors influencing deprescribing in frail individuals. Methods: A qualitative approach was employed and semistructured interviews were conducted between 9 April and 29 May 2024 with a sample of 30 general practitioners working in primary care facilities in Crete, Greece. The interviews were recorded and transcribed verbatim. Thematic analysis was performed on the basis of the Theoretical Domains Framework. Results: Several barriers to deprescribing were revealed, including a lack of expertise and motivation, inadequate communication skills, time constraints, and negative beliefs toward deprescribing held by physicians and patients. The lack of an established role for general practitioners in primary care, the absence of a national initiative targeting polypharmacy, and the influence of pharmacists and pharmaceutical representatives were highlighted as challenges. The identified facilitators included the incorporation of deprescribing recommendations and considerations for frail patients into guidelines, fostering a strong doctor-patient relationship, promoting shared decision-making, facilitating effective collaboration with caregivers, and utilizing nonpharmacological therapy. Conclusions: General practitioners encounter both barriers and facilitators when making deprescribing decisions for older adults, particularly those with frailty syndrome. Researchers and policymakers can use the findings of this research to guide future interventions and promote successful deprescribing practices
Brick by Brick: Assembly and Exploration of Metal–Organic Framework Thin Films
No full textCatalysis is essential for many industrial processes, from fertilizer and medicine production to renewable fuel generation. As the demand for clean energy grows, better catalysts for solar fuel production are needed. Metal–organic frameworks (MOFs) have emerged as promising candidates, where metal-based nodes and organic linkers form stable, customizable 3D structures. Embedding molecular catalysts into MOFs helps prevent unwanted interactions that often reduce their activity. For electrocatalytic applications, electrodes are modified with electrochemically active MOF thin films. However, controlling their thickness, which is crucial for performance, remains a challenge. This thesis investigates two synthesis techniques that allow thickness control: vapor-assisted conversion (VAC) for UiO-type MOFs (UiO = Universitetet i Oslo) and atomic layer deposition (ALD) combined with pseudomorphic replication (PMR) for porphyrinic MOFs. First, VAC was studied for the synthesis of crystalline UiO-67 thin films. While considered a straightforward method, reproducibility issues arose. Literature suggests that water plays a crucial role in forming zirconium clusters, but this study reveals that excess water, absorbed from atmospheric moisture, can harm MOF crystallinity. Fortunately, this effect can be countered by increasing the concentration of the modulator acetic acid, which competes with the linker for coordination sites at the nodes, slowing down crystallization. Next, the ALD/PMR approach was explored for the porphyrinic MOF family Al2(OH)2MTCPP (M = Co, Cu, Fe, Zn, H2; H2TCPP refers to the free-base porphyrin). ALD, a gas-phase technique, enables thickness-controlled deposition of inorganic coatings, such as metal oxides, while PMR transforms one material into another. By combining these techniques, various substrates (silicon, indium tin oxide-coated glass, gas diffusion electrodes, fluorine-doped tin oxide-coated glass, and copper) were coated with porphyrinic MOF layers using conventional or microwave-assisted heating. Here, the metal oxide serves as a node precursor, which, upon the introduction of a metalloporphyrin linker, forms the MOF layer. Beyond synthesis, the ALD/PMR strategy was explored for surface patterning. Using a mask during ALD creates a metal oxide template, which can be converted into a MOF pattern with sub-micrometer resolution. The synthesized Al2(OH)2CoTCPP@silicon composite was applied as a photocathode for solar fuel production, selectively reducing protons to hydrogen with 100% faradaic efficiency. Demonstrating the system’s photovoltage, the reduction onset potential of the photoelectrode was observed at more positive potentials compared to that of a dark cathode. The provided insights into synthesis parameters, surface patterning, and the application of MOF-modified electrodes for solar fuel production, highlight both the importance of controlled synthesis and the versatility of MOF materials