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- Wang, Dong, 1987-
(författare)
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New Reactions with Allyl- and Allenylboron Reagents : Transition-Metal-Catalyzed and Transition-Metal-Free Carbon-Carbon Bond Formation Processes
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organoboron compounds have been widely used in carbon-carbon bond formation reactions in organic synthesis and catalysis. This thesis is focused on cross-coupling reactions of allyl-, allenylboronic acids and their ester derivatives via transition metal catalysis or transition-metal-free processes.The first part of the thesis describes Cu-catalyzed C(sp3)-C(sp3) formation reactions involving allylboronic acids and α-diazoketones. This coupling process shows high γ-regioselectivity, resulting in branched allylic products. When stereodefined cyclic allylboronic acids were employed as the substrate, the relative facial configuration was retained in the reaction product.The second part involves Pd-catalyzed cross-coupling of allylboronic acid and α-diazoketones. The reaction proceeds with high α-regioselectivity, affording linear allylic products. Accordingly, the palladium- and copper-catalyzed cross-coupling of allylboronic acid and α-diazoketones occurs with opposite regioselectivity.The third part concerns a new transition-metal-free carbon-carbon bond formation between allenylboronic acids and in situ generated diazo compounds. The diazo compounds are generated from tosylhydrazones in the presence of base. The reaction is suitable for synthesis of densely substituted conjugated dienes with high Z-selectivity.In the final part, the allylation of quinones with allylboronates is presented. The reaction was performed without any catalyst or additive. Various quinones can be employed as substrates, including unsubstituted, monosubstituted benzoquinones and naphthoquinones.
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| 2. |
- de Ruijter, Markus J. T.
(författare)
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Mind & Well-being : The relationships between personality and health related pathology
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of the associations between personality, lifestyle and health related pathology has revealed important associations. These include associations with physical health such as the onset of cardiovascular disease, but also with mental and emotional health such as depression or life satisfaction. However, certain gaps in knowledge and methodology had persisted. This thesis contains several works that address those gaps and extend the knowledge and methodology in personality-related research.Study I utilized the large-scale UK Biobank cohort to examine personality traits in association with stroke risk. Proxy variables for the Big Five personality traits were inferred from the available data. Results indicate negative associations of the personality traits diligence and sociability, with incident stroke risk, suggesting potential protective effects.Study II employed Mendelian randomization to investigate causal relationships between specific subcategories of neuroticism and different subtypes of cardiovascular disease. Using the UK Biobank cohort, the study showed causal positive associations between depressed affect and two subtypes of cardiovascular disease: heart failure and myocardial infarction.Study III examined the associations between job satisfaction and personality traits related to executive functions: delay discounting, risk-taking, and sensation seeking. Proxy variables were created to infer delay-discounting and sensation seeking. Using data available in the UK Biobank, the study reveals a negative association between delay discounting and job satisfaction, and a positive association between risk-taking and job satisfaction.Study IV explored the association between genetic risk for autism spectrum disorder (ASD) and well-being in the general public, regardless of ASD diagnosis. The study employs polygenic risk scoring in the UK Biobank cohort and shows that the genetic risk for ASD is associated with all five well-being spectrum traits in a detrimental way, emphasizing the potential impact of a genetic predisposition for ASD on well-being.Finally, in Study V, the research proposed a novel method for studying general personality in Drosophila melanogaster. The method includes a new experimental environment, comprehensive recording and tracking, and subsequent analysis techniques, providing a foundation for further research into personality-like traits in the species.Overall, this thesis extends the knowledge and methodology in personality-related research and highlights the potential impact of personality traits on physical and mental well-being.
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| 3. |
- Luis, Israel
(författare)
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Walking efficiently with smart springs
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Numerous assistive exoskeletons have been developed in recent years to assist walking in individuals with and without motor disorders. A standard metric to measure the efficacy of assistance is the change in the metabolic energy cost between unassisted and assisted conditions. Various experimental methods, such as human-in-the-loop optimization, have been developed to find the optimal exoskeleton control to minimize metabolic energy. Such an approach is powerful yet time- and resource-intensive. In this regard, computational methods might complement state-of-the-art experimental approaches. Developing accurate models of the musculoskeletal system and neuromuscular commands could accelerate the development of exoskeletons and improve our understanding of human-exoskeleton interaction. The aims of the thesis were to model and simulate muscle-tendon mechanics and energetics of walking across speeds in unassisted conditions and with the support of ideal exoskeleton assistance with two modes of assistance: motor-based and spring-based actuators. The first three studies examined multiple musculoskeletal models, calibration methods of the muscle-tendon architecture, performance criteria for solving the muscle redundancy, and metabolic energy models to accurately estimate muscle excitations, fiber lengths, and metabolic energy cost compared to available experimental data. The musculoskeletal model proposed by Rajagopal et al. with calibrated muscle passive fiber-length curves and personalized Achilles and patellar tendon stiffness provided good agreement with muscle excitations and fiber lengths obtained from electromyographic signal and ultrasound imaging, respectively. Also, among multiple metabolic energy models in the literature, the model proposed by Bhargava et al. best estimated the average metabolic rates of the whole body compared to experimental measurements computed from spiroergometry. With the best estimations of muscle-tendon mechanics and energetics, the relative cost of the stance phase was predicted to increase significantly with walking speeds, and the metabolic cost of ankle plantarflexors was the highest among muscle groups and increased with walking speeds. The fourth study examined the optimal assistance to reduce muscle activations using motor-based and spring-based assistance of ankle plantarflexor, knee extensor, hip flexor, and hip abductor muscle groups. The largest reduction of muscle activation compared to unassisted conditions was obtained with hip flexor assistance with both actuation systems at high walking speeds. The reduction of metabolic rates compared to unassisted conditions was greater with walking speed with motor-based ankle plantarflexor assistance. In contrast, assisting this muscle group with spring-based actuation resulted in lower metabolic cost compared to unassisted conditions as walking speed increased. Interestingly, the decrease in muscle activations did not necessarily imply a reduction of metabolic energy cost compared to unassisted conditions, for instance with spring-based hip flexor and abductor assistance at some walking speeds. Metabolic energy rates during specific periods of the gait cycle were larger than in unassisted conditions due to increased muscle positive work, which is associated with high metabolic cost. The computational methods in the thesis might inspire future studies in the field. The software to calibrate muscle-tendon parameters, such as tendon compliance based on electromyography and muscle passive force-length curves based on ultrasound imaging, and to simulate exoskeleton assistance, are available in public repositories and can be adapted to integrate more experimental observations and simulate other motions than walking. Future studies will validate the predicted muscle-tendon mechanics with exoskeleton assistance.
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