Technical University of Denmark

PEGylated liposomes are well-known for their properties as long-circulating nanocarriers in drug delivery systems, where the structure and organization of the polyethylene glycol (PEG) coating critically influence their stability, circulation lifetime, and biological interactions. Given the crucial role of PEG coating attributes in these structured nanoparticles, it becomes essential to explore advanced technologies capable of specifically addressing the surface properties of liposomes. A detailed surface characterization, combined with nanoparticle composition analysis, enables deep insights into critical quality attributes of nanomedicines, which are essential for ensuring both quality and safety. In this study, small-angle X-ray scattering (SAXS) was employed to examine the structural organization of PEGylated liposomes, alongside their composition analysis using High-Performance Liquid Chromatography coupled to a Charged Aerosol Detector (HPLC-CAD). The liposomes were formulated through commonly used formulation strategies, such as pre- and post-insertion of various molecular mass, PEG2000 (PEG2K) and PEG5000 (PEG5K)-modified lipids. SAXS profiles revealed systematic variations in scattering features with increasing PEG content, indicating progressive changes in corona density and interfacial organization. In addition, core-multishell modeling confirmed that the liposomes prepared using both strategies were unilamellar with stable bilayers. Pre-insertion PEG2K liposomes showed pronounced reorganization of the outer interface, with higher PEG levels producing thicker, denser coronas consistent with a mushroom-like configuration. In post-insertion formulations, both PEG2K and PEG5K systems were well described by four-shell models. PEG2K post-insertion liposomes displayed thinner but denser coronas, whereas PEG5K yielded thicker, more hydrated layers that compacted with increasing PEG concentration. Despite these interfacial variations, the bilayer core remained largely unaffected, though pre-insertion induced marked PEG-lipid leaflet asymmetry. Overall, these findings demonstrate that PEG chain length, surface density, and incorporation strategy each play a critical role in shaping the structure and density of the PEG corona. By quantifying these factors, this work provides detailed insight into PEG organization at the liposome interface and supports the rational design and quality control of sterically stabilized liposomes.

We show that one can construct a germ of a local solution of systems of semi-linear second order partial differential equations (PDEs) from any given n -jet that satisfies the system up to the ( n − 2 ) -jet level. We treat in more details the case of harmonic map-germs to the unit sphere. Our results allow, for instance, to determine which local singularities a harmonic map to the sphere can have.

An integrated upstream process was developed for the high-level production of a low-immunogenic L-asparaginase mutant (EcaII P40S/S206C) in Escherichia coli, combining high-cell-density fed-batch cultivation with controlled induction and post-induction nutrient feeding. Biomass accumulation was achieved by exponential substrate feeding, followed by pH-stat-based nutrient supply during the expression phase. Induction protocols were optimized using biomass-specific IPTG dosing (µmol IPTG/gcell), applied either as a pulse or via exponential feeding. This combined strategy resulted in a maximum volumetric enzyme activity of 134,516 U/L and a specific productivity of 3387 U/gcell, corresponding to 91-fold and 24-fold increases, respectively, compared with standard batch cultivation. Overall, these results indicate that the coordinated control of feeding strategy and induction conditions substantially improves both volumetric and cell-specific productivity of recombinant L-asparaginase and provides a robust upstream framework for the efficient manufacture of improved enzyme variants.

Antifouling coatings are essential for controlling biofouling in the shipping industry. To improve fouling control, underwater cleaning is often employed, but this process can alter coating surfaces and release contaminants such as biocides and microplastics. This study investigates the impact of ultrasonic cleaning on an antifouling coating under controlled laboratory conditions. Commercial yacht coating samples were aged under laboratory conditions to form a leached layer and then subjected to ultrasonic cleaning with varying process parameters. Aggressive cleaning (1cm probe-coating surface distance, 5.4MPa acoustic pressure) significantly damaged the coating, thereby partially removing the leached layer, increasing surface roughness, and releasing microplastic particles and biocides into seawater. Gentler cleaning (4cm probe-coating surface distance, 1.5MPa acoustic pressure) caused no visible damage, yet microplastics and biocides were still released. Depending on cleaning conditions, the copper release ranged from 0.3 to 10μg/cm2, with similar mass amounts detected for released particles. To effectively mitigate environmental contamination, these findings highlight the importance of selecting appropriate cleaning parameters and capturing effluents during boat cleaning.

Low-temperature oxygen-ion conductors hold the potential to transform sustainable energy storage technologies, but faster conductors are needed. Herein, leveraging high-throughput Density Functional Theory calculations and Nudged Elastic Band workflows, we systematically screen 5400 hexagonal perovskite structures to evaluate oxygen-ion migration via interstitialcy mechanisms. Our findings reveal 29 promising candidate compositions, highlighting systems like Ba 7 V 4 MoO 20 and Sr 7 V 4 MoO 20 as highly viable candidates Beyond candidate identification, our analysis of the vacancy-mediated single-ion Potential Energy Surface reveals two distinct oxygen-ion migration pathways: conventional ion-hopping and a highly flexible lattice-assisted mechanism By quantifying structural descriptors, including Continuous Symmetry Measures, local strain, and polyhedral rotation, we establish that the lowest activation barriers correlate with the lattice-assisted pathway. Additionally, we find that this dynamic mechanism is strongly influenced by the size disparity between the A-site cation and the B-site atoms at the interlayer. A larger A-site cation expands the 2D lattice, providing the necessary crystallographic free volume to reduce interlayer friction. By mapping these fundamental structural prerequisites, this study clarifies the polyhedral dynamics of oxygen-deficient environments and provides a quantitative design rule to accelerate the discovery of next-generation solid electrolytes. • High-Throughput Screening: An autonomous DFT workflow analyzed 5400 hexagonal perovskite structures, identifying 29 promising oxygen-ion conductors. • Viable Candidates: Our computational screening identifies 29 promising candidate compositions, highlighting systems like Ba 7 V 4 MoO 20 and Sr 7 V 4 MoO 20 . • Mechanistic Insights: We revealed two distinct oxygen-ion migration pathways, conventional ion-hopping and a highly flexible lattice-assisted mechanism.

This study investigates the impact of key operational parameters, tangential velocity, idle/dynamic cycling, and sunlight exposure, on biofouling development and coating performance across three commercial marine coatings: an epoxy primer (EP), a copper-based self-polishing coating (AF-Cu), and a silicone-based fouling release coating (FRC). Dynamic immersion tests revealed that AF-Cu performance improved with increasing velocity due to enhanced biocide release, while FRC exhibited optimal performance at moderate speeds, with mechanical damage limiting efficacy at higher speeds. Intermittent exposure profiles demonstrated that longer continuous running phases promote self-cleaning in FRC and stabilize biocide release in AF-Cu, whereas frequent idling reduced coating effectiveness. Shading during idle periods significantly suppressed early-stage algal fouling on EP panels, though barnacle settlement increased later in the season, raising overall fouling ratings due to the disproportionate impact of hard fouling. No shading effect was observed for AF-Cu or FRC. Across all protocols, coating durability and alignment with vessel-specific operational profiles emerged as critical factors in fouling control. These findings emphasize that effective antifouling strategies must integrate both material performance and operational context. The results support the development of more resilient, responsive coatings and encourage operational practices that enhance coating function and longevity under real-world conditions. • Hydrodynamic conditions modulated biofouling settlement on coating surfaces and community structure. • High rotor speeds reduced fouling release coating performance due to mechanical surface degradation. • Extended idle periods in a dynamic cycle governed the balance between fouling growth and removal. • Shading limits early algae fouling, while increasing barnacle settlement at later stages.

• Poor indoor air quality is preventable public health risk. • The updated Energy Performance of Buildings Directive includes indoor air quality. • Europe has a major opportunity to protect the health of building occupants. • The European Union should adopt a health-based framework for indoor air quality. Poor indoor air quality is a common and preventable public health risk that contributes to chronic disease, infectious disease transmission, and economic losses. Europe’s updated Energy Performance of Buildings Directive integrates indoor environmental quality into building policy for the first time, representing a major opportunity for Europe to protect the health of building occupants and set an example for the world. With a May 2026 deadline approaching, EU Member States should adopt a health-based framework for indoor air quality and aim to harmonize standards across Europe.

• A transfer-free strategy enables the growth of WS 2 /MoS 2 vertical heterostructures. • Oxygen-deficient MoO 3 −x and WO 3 −x PLD films provide effective solid-state precursors. • Direct conversion of oxide bilayers yields uniform WS 2 /MoS 2 stacking and clean interfaces. The reliable fabrication of vertically stacked transition metal dichalcogenide (TMD) heterostructures with clean, well-defined interfaces is essential for next-generation opto-electronic and quantum technologies. Here, we demonstrate a fully transfer-free synthesis route for WS 2 /MoS 2 heterostructures by combining pulsed laser deposition (PLD) of oxygen-deficient MoO 3 −x and WO 3 −x thin films with high-temperature sulfurization. Oxygen vacancies in the reduced oxides act as reactive sulfur incorporation sites, enabling efficient conversion into a crystalline monolayer of MoS 2 and few-layer WS 2 . We compare two routes direct sulfurization of an in situ WO 3 −x /MoO 3 −x bilayer and a sequential process in which WO 3 −x is deposited onto pre-formed MoS 2 . Both approaches yield vertically stacked WS 2 /MoS 2 heterostructures with clean interfaces and strong interlayer coupling; however, the direct bilayer conversion produces more uniform stacking and better structural quality. This vacancy-driven oxide conversion strategy provides scalable control over layer thickness, morphology, and interfacial sharpness while avoiding polymer residues and the mechanical damage inherent to transfer-based assembly. These results establish oxygen-deficient metal oxides as versatile solid-state precursors for the growth of high-quality TMD heterostructures suitable for advanced photonic, electronic, and quantum devices.

This study presents the validation of a computational fluid dynamics simulation model for a 1:20 scale raft-type wave energy converter subjected to regular incident waves, along with experimental wave tank test results. A damper model in the simulations, calibrated using time-varying damping coefficients, is found to be sufficient to approximate the characteristics of the nonlinear power take-off system. In most test cases, the numerical results correspond appropriately with the model test results, exhibiting a deviations below 10% in terms of capture width ratio, even under steep wave conditions. Stable simulations with steep waves are achieved through an optimized mesh configuration with adaptive refinement. Moreover, variations in device mass and width are identified as key design considerations. Increasing the latter results in higher absorbed power but lower capture width ratio. Flow visualizations are presented in which events with high nonlinearity, such as slamming and overtopping, are identified. These events can contribute to the reduction in power absorption observed in the case of steep waves. • CFD of raft-type WECs agrees well with experiments, even in steep waves. • Time-varying PTO damping captures nonlinear system behavior. • Optimal mesh is proposed for closely spaced raft simulations. • Flow visualizations identified key nonlinear effects. • Sensitivity to mass, center of mass, length, and width is shown.