Chalmers ODR

Single particle characterisation of lipidbased nanoparticles using automated Raman trapping analysis

(2025) Palmgren, Lukas

Liposomes are self-assembled lipid structures comprising a lipid membrane bilayer encapsulating an aqueous core. They have for a long time been acknowledged as appropriate delivery vectors for the delivery of both hydrophobic and hydrophilic cargo. However, they are not able to achieve active targeting of specific cells or tissues. Extracellular vesicles (EVs) are lipid membrane-bound vesicles ranging in diameter from 10s to 1000s of nm which are produced by almost all cells in the body. They have shown effective targeting ability and are innately biocompatible. However, they are heterogeneous and hard to purify in large enough amounts for use in drug delivery. It has been suggested that designing liposomes, which can mimic extracellular vesicles, might overcome these issues and allow better drug delivery vectors to be designed. In this thesis, a protocol to characterize liposomes on the single particle level was developed, using a single particle automated Raman trapping analysis (SPARTA) instrument which combines Raman spectrometry with optical trapping. As a model system, liposomes of varying lipids with varying degrees of cholesterol were studied, since high cholesterol content has often been reported for extracellular vesicles. This leads to the report having two goals, the first being to optimize and learn SPARTA in order to study particle on a single particle level, with a high throughput. The second goal was to characterize the efficiency of cholesterol encapsulation at high mol % and investigate how cholesterol affects the phase behavior of particles on the single particle level using SPARTA as the main method. Large unilamellar vesicles were formulated using three different phospholipids DPPC, POPC and DOPC. The difference between the three lipids are the amount of double bond unsaturations on the lipid tails; DPPC have zero, POPC have 1 and DOPC have 2. These three phospholipids were used to formulate vesicles with different amounts of cholesterol ranging from 0-70 mol % cholesterol for each lipid. The different compositions were then studied primarily using SPARTA with verification of lipid phase behavior using small and wide angle X-ray scattering (SAXS/WAXS) as a complimentary method. To experimentally determine maximum encapsulation of cholesterol into DPPC, POPC and DOPC liposomes, liposomes with compositions ranging from 40-70 mol % cholesterol were also analyzed using 1H − NMR. Initial experiments allowed the concentration range for single particle measurements to be determined. It was also shown that the particles studied in this thesis were homogeneous in composition, since only the signal intensity decreased upon increasing dilution. Next, it was shown that SPARTA can be used effectively to show cholesterol saturation which was confirmed by proton NMR, and double bond ratio and conformational order which were corroborated with SAXS/WAXS measurements. WAXS also showed formation of cholesterol crystals at higher cholesterol amount. SAXS/WAXS also allowed changes in D-spacing for specific lipid mixtures to be characterized with increased cholesterol. Together, these results showcase the possibles to characterise lipid vesicles on the single particle level using Raman spectroscopy, and specifically, how the effect of cholesterol on lipid phase behavior can be quantified on a single particle level. The findings here on these model systems allow us to better apply single particle automated Raman trapping analysis to study more complex, biological samples.

Effects of deformation differences on connections in hybrid structure

(2025) Widén, Elin; Larsson, Malin

Hybrid structures that combine timber and concrete have become an increasingly attractive solution in modern construction, making use of the benefits of both materials. Timber offers a renewable, lightweight, and environmentally friendly alternative, while concrete provides stability and stiffness. However, the differences in long-term deformations between timber and concrete creates significant challenges, especially at the connections where these materials interact. If the timber elements deform more than the concrete ones in the structure, the connection that combine these, must accommodate the displacement mismatch. Such differences can lead to an increase in stress and forces, and potential long-term issues affecting the safety and performance of the structure. The aim of this Master’s thesis is therefore to investigate how these differential long-term deformations influence the structural performance of a timber-to-concrete connection in a hybrid structure. A specific focus is placed on an embedded steel knife plate connection, commonly used for its aesthetic appeal and fire-protective properties. Understanding how these deformations develop and interact at the connection will provide valuable insights for future designs. To achieve this aim, a finite element model (FEM) was developed in ABAQUS. This model simulates the connection under imposed displacements that represent long-term deformation effects. The analysis includes the distribution of forces in bolts and screws, stress concentrations in the timber beam, and the overall moment and stiffness of the connection. Different configurations of the connection were explored to identify the most critical factors that contribute to structural performance. The results of the study demonstrate that the difference in long-term deformations between timber and concrete significantly influences the load distribution within the connection. In particular, the analysis highlights the increased stresses and forces in key areas, such as the axial forces in the screws and the stress parallel to grain in the timber beam. The findings suggest that these effects should be carefully considered in connection design, especially when using embedded steel knife plate connections in hybrid structures. Furthermore, the results indicate the potential advantages of having a pinned connection and also allow steel parts to plasticise to decrease the moment development in the connection.

Impact of ionic doping on the normal and superconducting properties of YBCO thin films and nanowires

(2025) Balistreri, Angelo

Despite almost 40 years of intense research, high-temperature superconductivity in cuprates remains one of the most intriguing unsolved problems in condensed matter physics. The phase diagram of these materials, which describes how their properties vary with temperature and doping, is extremely complex: even the normal state above the superconducting critical temperature is characterized by multiple regions and symmetry-breaking orders associated with charge, magnetic, lattice, and orbital excitations. The interplay and competition among these orders, which may be at the origin of the pairing mechanism, are still far from being fully understood. In this thesis, to shed light on these phenomena and gain a clearer picture of normalstate orders and of their competition with superconductivity, we focus on YBa2Cu3O7−δ (YBCO), where doping is controlled by oxygen content, and we introduce a small fraction of Zn atoms substituting Cu. This chemical substitution modifies the CuO2 planes, which constitute the core of both the superconducting and normal-state properties of this family of materials. In particular, I optimized the growth of Zn-doped YBCO thin films on STO substrates via pulsed laser deposition. The partial substitution of Cu with non-magnetic Zn atoms effectively suppresses superconductivity, revealing the underlying normal-state properties hidden beneath the superconducting dome. To explore different regions of the phase diagram and understand the effect of Zn, films were grown across a range of oxygen dopings, from underdoped to strongly overdoped regimes, and for two different Zn concentrations. The structure, morphology, and transport properties of these films were characterized: these measurements allowed me to precisely determine the doping and build the complete phase diagrams for both Zn levels. Our results reveal a clear suppression of Tc, an expansion of the insulating region, and a relative invariance of the pseudogap temperature. Finally, the films were patterned into Hall bars and nanowires to investigate transport properties via currentvoltage characterization and transport measurements down to the nanoscale, providing information about material homogeneity at the nanodomain level. This work contributes to the broader effort of disentangling the mechanisms behind unconventional superconductivity by accessing the normal state through chemical doping. Moreover, it establishes a new material platform that paves the way for future investigations in both transport and spectroscopic experiments.

Svillen, Reinterpreting the Boathouse Clusters of Bohuslän - Översikt

(Chalmers tekniska högskola // Institutionen för arkitektur och samhällsbyggnadsteknik, 2024-06-01) Smith, Julianna; Erixon, Anna

This thesis explores the potential of inserting contemporary architecture within the context of the Bohuslän archipelago. Through the design of a group of small buildings, based on in-depth studies of the architectural and typological features of local vernacular architecture, the thesis aims to revitalise the historical cluster typology through an architectural reinterpretation. More specifically the research focuses on ‘Sjöbodar ́ (fishermen’s boathouses). The research encompasses the sjöbod as an individual piece of traditional, vernacular architecture, including aspects of tectonics, as well as the proliferation of such buildings in larger groups or clusters. Within the cluster, a narrow, alley-like space is formed between the buildings, referred to as Svillen. Svillen is defined as the space closest to the boathouse, protected by an eave above. It was typically used as a place of practising labour, for storage, or drying nets, and was shared between the adjacent boathouses. Svillen has become of interest to the thesis as it raises questions concerning the role of the collective, i.e. the cluster, versus the role of the individual boathouse. Lastly, the thesis has explored the social culture in the clusters through the ‘Ljugarbänk’ (the liar’s bench) which is present in the stories about the fishing community. The design proposal consists of a cluster that is located in the Toftenäs nature reserve in southern Bohuslän. It houses common areas and accommodates temporary overnight stays for hikers and boaters, as it lies in a natural harbour. The design evokes the memory and identity of the fishing village through a reinterpretation of the traditional construction and building typology, and becomes a contemporary addition to the harsh coastal landscape. The proposal has explored design in 3 different scales; firstly, the detail in joinery and paraphrasing of Ljugarbänken, secondly, the Sjöbod as an individual piece of architecture, and lastly the cluster, including Svillen – the relationship between the buildings themselves and the sea.

Svillen, Reinterpreting the Boathouse Clusters of Bohuslän - Landskap

(Chalmers tekniska högskola // Institutionen för arkitektur och samhällsbyggnadsteknik, 2024-06-01) Smith, Julianna; Erixon, Anna

This thesis explores the potential of inserting contemporary architecture within the context of the Bohuslän archipelago. Through the design of a group of small buildings, based on in-depth studies of the architectural and typological features of local vernacular architecture, the thesis aims to revitalise the historical cluster typology through an architectural reinterpretation. More specifically the research focuses on ‘Sjöbodar ́ (fishermen’s boathouses). The research encompasses the sjöbod as an individual piece of traditional, vernacular architecture, including aspects of tectonics, as well as the proliferation of such buildings in larger groups or clusters. Within the cluster, a narrow, alley-like space is formed between the buildings, referred to as Svillen. Svillen is defined as the space closest to the boathouse, protected by an eave above. It was typically used as a place of practising labour, for storage, or drying nets, and was shared between the adjacent boathouses. Svillen has become of interest to the thesis as it raises questions concerning the role of the collective, i.e. the cluster, versus the role of the individual boathouse. Lastly, the thesis has explored the social culture in the clusters through the ‘Ljugarbänk’ (the liar’s bench) which is present in the stories about the fishing community. The design proposal consists of a cluster that is located in the Toftenäs nature reserve in southern Bohuslän. It houses common areas and accommodates temporary overnight stays for hikers and boaters, as it lies in a natural harbour. The design evokes the memory and identity of the fishing village through a reinterpretation of the traditional construction and building typology, and becomes a contemporary addition to the harsh coastal landscape. The proposal has explored design in 3 different scales; firstly, the detail in joinery and paraphrasing of Ljugarbänken, secondly, the Sjöbod as an individual piece of architecture, and lastly the cluster, including Svillen – the relationship between the buildings themselves and the sea.

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