Publikationer från Uppsala Universitet
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Ferrous and Ferric N-Heterocyclic Carbene Complexes : Characterization and Applications in Photoredox Catalysis
No full textIron complexes are emerging as favourable substitutes to noble metal complexes as photocatalysts due to iron being earth-abundant and inexpensive. Much of the recent progress has been enabled by the strong electron-donating character of N-heterocyclic carbene (NHC) ligands that strongly destabilizes metal-centred (MC) states of FeNHC complexes and thereby greatly extends the lifetimes of their charge transfer (CT) states that are otherwise rapidly deactivated via low-lying MC states. The first part of this thesis successfully employed FeNHC complexes in different photoredox catalysis (PRC) reactions and an example of high-turnover catalytic hydrogen production. The latter was accomplished with the benchmark ferric bis-tridentate scorpionate complex [FeIII(phtmeimb)2]+ (phtmeimb = phenyl(tris(3-methylimidazol-1-ylidene))borate) which has a 2LMCT state lifetime of two nanoseconds and excellent photostability. It was further employed in two PRC reactions that yielded synthetically-useful organic compounds, where fast and efficient reductive quenching of the 2LMCT state by various amine donors with cage escape yields between 2 and 22 % were observed. A tris-bidentate complex with favourable excited-state (ES) redox properties and lifetimes in both oxidation states, [FeII,III(btz)3]2+,3+ (btz = 3,3’-dimethyl-1,1’-bis(p-tolyl)-4,4’-bis(1,2,3-triazol-5-ylidene)), was employed in a two-photon PRC reaction utilizing both oxidative and reductive quenching steps, making the PRC reaction overall more efficient. The second part of this thesis describes the electrochemical and photophysical characterization of novel FeNHC complexes with three different motifs in view of their potential suitability as photocatalysts. (i) For a series of ferric bis-tridentate complexes with cyclometalating ligands, not only were their emissive 2LMCT states with lifetimes of hundreds of picoseconds approaching values previously obtained with the [FeIII(phtmeimb)2]+ motif, their electrochemical and ES properties were more tunable by substituent effects. (ii) For the (NHC)4(bpy)2 bis-tridentate complexes [Fe(btz)2bpy]2+,3+ (bpy = 2,2'-bipyridyl) and [Fe(btz)2mbpy]2+,3+ (mbpy = 4,4'-dimethyl-2,2'-bipyridyl), both ferrous and ferric analogues offered insufficient ES lifetimes on the order of ten ps. The ferrous mbpy variant featured however a more long-lived, presumably MC state that deserves further characterization, also in regard to its potential reactivity. (iii) For the ferrous analogue of [FeIII(phtmeimb)2]+, the strikingly-short picosecond 3MLCT state lifetime concludes that even the phtmeimb- ligand with superior σ-donating ability cannot sufficiently prevent the relatively high-energy 3MLCT state from rapid deactivation.
Is it possible for parents to endure a stillbirth? Initial experiences, perceptions and strategies : individual in-depth interviews in Sweden 2021-2023
No full textBackground Stillbirth occurs at a rate of 3.0 per thousand in Sweden. However, few studies have focused on the initial experiences of parents facing a stillbirth. The aim of this qualitative study is to deepen and broadly explore parents’ initial experiences, perceptions, internal processes and strategies from the moment of suspicion or awareness of stillbirth until one month after the event. Methods Ten individual in-depth interviews were conducted between 2021 and 2023, and data were evaluated using thematic network analysis. Results Two key themes emerged: ‘Following the journey – from suspicion to acceptance’ and ‘Support, structured activities and processes after stillbirth’. These themes captured the significant consequences of a sudden, unexpected and devastating end to pregnancy. The suspicion and eventual diagnosis of stillbirth were initially associated with sudden discomfort, fear, overwhelming grief, and intense pain. Nevertheless, a vaginal birth was regarded as the optimal mode of delivery for both physical and emotional wellbeing. Caring for the stillborn baby through physical proximity for an extended period of time helped parents comprehend and cope with their grief, while also affirming their sense of parenthood. Conclusions This study sheds light on the profound and devastating impact of stillbirth on parents who are confronted with the loss of their long-awaited and cherished baby. The intense grief and pain experienced by parents during the first month after stillbirth were described as an ongoing heavy burden, persisting day and night, and reflected in poor/very poor mental health. Despite the immense challenges faced by parents, the study highlights the importance of developing individual coping strategies to deal with this tragic and irreversible life-changing event
Compton scattering from proton pairs : illustrating weak and strong measurements
No full textNeutrons interacting with protons in Compton scattering is here chosen as an example of a non-trivial quantum measurement. It illustrates a situation where a probe particle makes an observation (a weak measurement) of the studied protons, preparing for a final state in which one of them takes up the recoil in the collision. The proton is ejected during a strong (projective) measurement that selects one particular momentum value out of the proton's initial distribution of momentum states. This course of events in the measurement process is evidenced by the observation that destructive interference appears during the weak interaction stage which leads to a strongly reduced neutron cross section for the proton system
Does leadership promote a cleaner climate?
No full textThe Paris Agreement encourages developed countries to lead in reducing emissions. Using a model of national emissions, I examine whether leadership improves global welfare. The results suggest that leadership reduces global emissions when the leader's abatement generates cost-reducing spillover effects or conveys private information about abatement costs. With spillover effects, the leader abates more to incentivize a greater reduction of emissions by followers. Under private information, the leader abates more to signal the abatement cost. If it has to choose between transparency and no transparency, the leader commits to transparency despite this being inefficient. Besides, I find sequential abatement stable against unilateral deviation
An experimental methodology to determine damage mechanics parameters for phase-field approach simulations using material extrusion-based additively manufactured tensile specimens
No full textThe 3D printing or material extrusion-based additive manufacturing has evolved from a promising fabrication technology to a mature method that can be integrated into numerous applications. However, this technique involves a large number of variables that significantly affect the resulting structure. In addition, this dependence hinders the development of numerical models to estimate the mechanical behaviour of 3D-printed components with different printing configurations. Hence, the phase-field approach is presented to predict crack propagation through a relatively simple energy balance minimisation problem. Nevertheless, this computational method requires specific parameters to be determined. Therefore, an experimental methodology based on tensile tests is proposed to mechanically characterise the material and analytically define the necessary fracture parameters, including strength and critical energy release rate, from the experimental results. Unnotched and notched specimens, fabricated via material extrusion using a sustainable thermoplastic, are studied under different configurations to analyse fracture mechanisms while addressing strategies to minimise printing defects. Additionally, an open-source numerical predictive tool by means of the phase-field fracture modelling is developed, along with the assessment of the essential length scale parameter. The combination of experimental and numerical studies validates the proposed methodology, and also demonstrates the ease of reproducing for further case studies
Ceftazidime-avibactam (CAZ-AVI) pharmacokinetics in critically ill patients undergoing continuous venovenous hemodiafiltration (CVVHDF)
No full textPurpose: To investigate the pharmacokinetics (PK) of ceftazidime-avibactam (CAZ-AVI) in critically ill patients undergoing continuous venovenous hemodiafiltration (CVVHDF), and compare with a general phase III trial population. Methods: A prospective PK study was conducted in critically ill patients who received CVVHDF for acute kidney injury, treated with CAZ-AVI (1000/250 mg or 2000/500 mg q8h). Plasma and CVVHDF-circuit samples were collected to determine CAZ-AVI concentrations. Individual PK parameters at steady-state were estimated using non-compartmental analysis. For visual comparison, plasma concentrations from CVVHDF patients were overlaid with simulated data from patients not receiving CVVHDF based on previously developed population PK models. Results: A total of 35 plasma samples and 16 CVVHDF-circuit samples were obtained from four patients, with two patients sampled on two separate occasions. Median total clearance and volume of distribution were 4.54 L/h and 73.2 L for CAZ and 10.5 L/h and 102 L for AVI, respectively. Median contribution of CVVHDF to total clearance was 19.8% for CAZ and 5.3% for AVI. Observed CAZ-AVI PK profiles were generally within the 90% confidence interval of model predictions, but the observed concentrations were notably lower early (0-2 h) and higher later (4-8 h) in the dosing interval, suggesting a higher volume of distribution. Conclusions: These results suggest that the CAZ-AVI dose regimens used in this study can be applicable in critically ill patients undergoing CVVHDF, despite the different shape of the PK profiles observed in this population. Further research with a larger patient cohort is warranted to validate and refine these findings.De två sista författarna delar sistaförfattarskapet</p
Spaceflight and Exercise: The Impact of the Protein CDKN1A/p21 on Bone Regeneration in Mice
No full textAstronauts spending extended periods of time in microgravity experience significant bone loss, and as missions grow longer and the prospect of off-Earth settlements become more realistic, it is critical to understand how that type of environment affects the human body. This thesis aimed to contribute to the field by investigating the effects of microgravity unloading on bone tissue regenerative homeostasis in mice from NASA’s Rodent Research-10 mission, with a focus on osteoclasts and osteoblast dynamics, in mice that have been flown to the International Space Station, ground control mice, and mice that have been allowed to run on wheels in normal gravity. The protein CDKN1A/p21 is believed to be a disuse- induced inhibitor of osteoblast progenitor proliferation during osteogenesis. In addition, Cdkn1a-null mice are highly regenerative, suggesting that its deletion might interfere with osteogenic homeostasis during disuse in microgravity. Due to these factors, comparing the three different modes of loading of the bones for wildtype mice and mice with the Cdkn1a gene deleted became the focus of this study. The osteoclast and osteoblast populations and their activity in the proximal femur of mice was compared for six individuals in each of the six groups. It was done through staining of the cells, followed by imaging using both conventional and confocal microscopy, followed by image analysis for quantification. Confocal microscopy was also used in a novel correlative methodology to generate stitched images of the femoral midshaft to visualise bone regeneration and compare with the conventional methods. The conventional methods of staining indicated that osteoclasts are larger in size in the absence of the gene Cdkn1a, leading to more bone resorption. The results also indicated that the running wheel group had more and larger osteoclasts, especially compared to the flight group, highlighting the different extremes of loading during exercise and unloading in microgravity. The results did not resolve any significant difference between the groups when it came to the size and number of osteoblasts, not for the genotype or the condition. The imaging of the femoral midshaft, carried out with the novel method, offered greater spatial and temporal coverage, and suggested that the small differences in osteoclast numbers and size for the flight and running wheel conditions might be the result of limited sampling in histological tissue sections, as well as high variability in sampling areas due to highly localised areas of osteoclastic degradation. The novel method showed more endosteal remodelling activity (increased pitting and mineralisation) for the running wheel and flight groups, compared to the ground control, versus results from the conventional method where statistical tests showed no statistically significant difference between the groups. The conventional methods were deemed inadequate when it comes to rare samples such as space-flown ones, which was why a series of novel methods to analyse bone remodelling has been developed by the Bone and Cell Signaling Laboratory at NASA Ames Research Center. The novel methods can be used to produce more data and better results, and in conjunction with the results from this thesis, can be used in future applications to resolve bone loss in astronauts as well as in people on Earth affected by bone-related diseases.
The philosophical health compass : A new and comprehensive assessment tool for researching existential dimensions of wellbeing
No full textThis paper introduces the Philosophical Health Compass (PHC), a quantitative assessment tool designed to complement qualitative research methods in investigating philosophical aspects of human wellbeing. The PHC evaluates six dimensions of philosophical health identified through previous research: bodily sense, sense of self, sense of belonging, sense of the possible, sense of purpose, and philosophical sense. While qualitative approaches in philosophical health excel at capturing rich individual narratives, their limitations in standardization and scalability constrain systematic research across populations. The PHC addresses this methodological gap by translating comprehensive philosophical concepts into measurable variables, enabling researchers to conduct comparative analyses, and integrate philosophical dimensions into an established wellbeing framework. This instrument is grounded in the SMILE_PH interview methodology introduced in 2023 by Luis de Miranda in the present journal, which has indicated through extensive field application that philosophical and existential health can be systematically explored through these six interrelated dimensions. We present the compass, its theoretical foundations, methodology, and potential research applications. By offering a standardized approach to evaluating philosophical wellbeing, the PHC creates new possibilities for interdisciplinary research while acknowledging that this questionnaire is not meant to replace the depth of the qualitative SMILE_PH dialogue, but rather to facilitate it
Continuous Wave Radar Waveforms for Integrated Communication and Sensing
No full textISAC is a means of enabling one waveform to accomplish two goals: detect targets and send information, which is spectrum efficient. To obtain satisfactory performance in both aspects, however, well-chosen trade-offs needs to be made. Requiring multiple transmitters to operate simultaneously increases the complexity and demands of the waveforms. This thesis project aims to investigate and compare different CW radar waveforms for ISAC and their ability to be used with multiple transmitters in a multistatic scenario. To this purpose, various waveforms (e.g., LFM-MPSK, OFDM) and multiple access techniques (e.g., FDMA, CDMA) are investigated and evaluated by combining them in different ways. For a fixed 50 MHz bandwidth in particular, MATLAB simulations are performed in which an additive white Gaussian noise channel with equal power line-of-sight paths from up to eight spatially separated transmitters; the received waveforms are first demodulated, during which the throughput and BER are calculated, then recreated and used for matched filter processing during which the sidelobe levels are calculated. The received waveforms are first demodulated during which the throughput and bit error rate is calculated, then recreated and used for matched filtering processing during which the sidelobe levels are calculated. The results have shown that, having no coding is the least robust but gives the highest throughput; radar metrics uncover clear trade-offs: increasing information capacity using higher-order modulation techniques, shorter codes, or more symbols per integration period generally raises mean sidelobe levels. It can be concluded overall that, when multiple transmitters are used, using longer Kasami codes provides the best compromise between BER robustness and low cross-correlation sidelobes. The conclusion of this project requires further work to verify. In particular, a more realistic simulation environment is needed as well as real-world measurements. In addition, using other codes and waveforms to compare with the results is valuable.
Lärande under artificiellt ljus : En studie om AI:s påverkan på kompetensutveckling hos juniora revisorer
No full textI takt med att artificiell intelligens (AI) integreras alltmer i revisionsbranschen väcks frågor om hur tekniken påverkar yrkets framtid. Särskilt intressant är hur kompetensutvecklingen hos juniora revisorer förändras. För att undersöka dessa frågor har studien genomförts med åtta semistrukturerade intervjuer med seniora och juniora revisorer från byråer av olika storlek i Sverige. Resultaten indikerar att AI inte enbart effektiviserar arbetsprocesser utan också omformar förutsättningarna för lärande. När rutinuppgifter i allt högre grad automatiseras minskar möjligheten till erfarenhetsbaserad kunskapsutveckling, vilket traditionellt har främjat professionellt omdöme. I stället får mer komplexa arbetsmoment en central roll i lärandeprocessen. AI anses därför inte utgöra en avlastning från lärande, utan snarare förstärka behovet av det. Detta medför ökade krav på handledning, reflektion och ett medvetet organisatoriskt ansvar. Studien visar att teknisk förståelse, kritiskt tänkande och kommunikativ förmåga blir allt viktigare egenskaper, medan det mänskliga omdömet fortsatt är avgörande. AI:s påverkan avgörs således inte enbart av tekniken, utan även av dess kontextuella tolkning och implementering