The Research Award of the Faculty of Science of the University of Gothenburg recognizes development of a research specialization that significantly contributes to novelty in the faculty’s research. The award recipient receives a diploma and a research grant of SEK 250,000. This year, the award ceremony will be held on 19 October.
A short interview with Giovanni Volpe regarding this achievement can be found at the link: Giovanni Volpe awarded the Faculty of Science’s 2023 Research Award.
Title: Controlling Active Clusters Using Wave-Shaped Light Patterns
Abstract:
Colloidal systems appear in various contexts. In some of these systems, thermophoretic forces can arise around otherwise passive particles when they are illuminated, leading to the emergence of complex behaviours. These types of systems has been extensively studied under constant, uniform light where the emergent behaviours are simply activated and deactivated. The aim of this project is to show that the emergent behaviour can not only be activated and deactivated, but also controlled by employing more complex light patterns.
The model used in this project includes Brownian motion and thermophoretic forces, with collisions between particles being resolved by a volume exclusion method. The thermophoretic forces are activated by employing travelling wave light patterns to affect the behaviours of different clusters formed as a result of these forces. Two different patterns are then superimposed to show that more complex light patterns can induce more complex behaviours.
This study is mostly qualitative in nature and only conducted in simulations. While the parameter space has only been roughly explored and the study needs to be validated through physical experiments, the results of the project indicate that a more comprehensive exploration of the parameter space for a broader range of clusters can be of interest.
Supervisor: Agnese Callegari
Examiner: Giovanni Volpe
Opponent: Simon Carlson
Place: Nexus
Time: 18 September, 2023, 17:00
Bringing microplankton to focus: Holography and deep learning
Harshith Bachimanchi
21 September 2023, 11:15 AM CEST
The marine microbial food web plays a central role in the global carbon cycle. However, our mechanistic understanding of the ocean is biased toward its larger constituents, while rates and biomass fluxes in the microbial food web are mainly inferred from indirect measurements and ensemble averages. Yet, resolution at the level of the individual microplankton is required to advance our understanding of the microbial food web. Here, we demonstrate that, by combining holographic microscopy with deep learning, we can follow microplanktons throughout their lifespan, continuously measuring their three-dimensional position and dry mass. The deep-learning algorithms circumvent the computationally intensive processing of holographic data and allow rapid measurements over extended time periods. This permits us to reliably estimate growth rates, both in terms of dry mass increase and cell divisions, as well as to measure trophic interactions between species such as predation events. The individual resolution provides information about selectivity, individual feeding rates, and handling times for individual microplanktons. The method is particularly useful to detail the rates and routes of organic matter transfer in micro-zooplankton, the most important and least known group of primary consumers in the oceans. Studying individual interactions in idealized small systems provides insights that help us understand microbial food webs and ultimately larger-scale processes. We exemplify this by detailed descriptions of micro-zooplankton feeding events, cell divisions, and long-term monitoring of single cells from division to division.
The article related to this presentation can be found at the following link: Microplankton life histories revealed by holographic microscopy and deep learning.
The recorded presentation can be found here:
Rebeca Ferrer Campos, Harshith Bachimanchi, Giovanni Volpe, Katherine Villa
Nanoscale (2023)
doi: 10.1039/D3NR03804A
Micromotors have emerged as promising tools for environmental remediation, thanks to their ability to autonomously navigate and perform specific tasks at the microscale. In this study, we present the development of MnO2 tubular micromotors modified with laccase for enhanced oxidation of organic pollutants by providing an additional oxidative catalytic pathway for pollutant removal. These modified micromotors exhibit efficient ammonia generation through the catalytic decomposition of urea, suggesting their potential application in the field of green energy generation. Compared to bare micromotors, the MnO2 micromotors modified with laccase exhibit a 20% increase in rhodamine B degradation. Moreover, the generation of ammonia increased from 2 to 31 ppm in only 15 min, evidencing their high catalytic activity. To enable precise tracking of the micromotors and measurement of their speed, a deep-learning-based tracking system was developed. Overall, this work expands the potential applicability of bio-catalytic tubular micromotors in the energy field.
Matthias Karg
20 September 2023, 12:30, Nexus
Microgels are soft polymeric objects with an internal gel-like structure and overall dimensions in the colloidal regime [1]. It is known that microgels strongly adsorb to liquid/liquid and liquid/air interfaces. Many studies in the last two decades attempted to understand the phase behavior of soft, deformable microgels at such liquid interfaces. Typically, the microstructures in dependence on applied surface pressure are studied ex situ using transfer of microgel monolayers from the liquid to a solid interface followed by investigation with different types of microscopies. Interestingly, in situ studies at the liquid interface are scare to nonexistent.
We tackled two challenges in this respect: 1) We managed to synthesize core-shell microgels that are large enough to be studied by optical microscopy or small-angle scattering using light [2]. 2) We build a setup that combines a Langmuir trough with small-angle light scattering (LTSALS) that allows for the large area study of monolayers during compression with excellent resolution in time [3]. In this work we present first results of the in situ analysis of microgel monolayers at air/water interfaces. Instead of the commonly reported solid-solid isostructural phase transition [4,5], we find a continuous compression of the monolayer with continuously decreasing interparticle distances [3]. Furthermore, drying of a thin liquid film with the monolayer at the liquid/air interface on hydrophilic and hydrophobic substrates shines light on the complex interplay between softness, adhesion and capillary interactions. We then studied the role of uniaxial compression/expansion by using our LT-SALS setup. Upon compression and/or expansion the monolayer remains somewhat anisotropic and a fast and a slow relaxation process is observed during an equilibration phase, i.e. when compression or expansion is stopped. Possible explanations for this behavior will be discussed.
References
[1] M. Karg, et al., Langmuir, 2019, 35, 6231-6255.
[2] K. Kuk, L. Gregel, V. Abgarjan, C. Croonenbrock, S. Hänsch, M. Karg, Gels 2022, 8, 516.
[3] K. Kuk, V. Abgarjan, L. Gregel, Y. Zhou, V. Carrasco-Fadanelli, I. Buttinoni, M. Karg, Soft
Matter, 2023, 19, 175-188.
[4] M.Rey, et al., Soft Matter, 2016, 12, 3545-3557.
[5] A. Rauh, et al., Soft Matter, 2017, 13, 158-169
Giovanni Volpe
AI Photonics, Donostia, Spain
Date: 12 September 2023
Kate Porter
IOP Publishing
Do you want your article to stand out from the crowd, improving your chances of publication in this highly competitive industry? If so, you won’t want to miss this talk from Kate Porter, Senior Publisher from IOP Publishing! During this talk, Kate will provide you with a toolkit to help you navigate the world of academic publishing and share some top tips to help you get published.
Topics covered in this talk include:
Date: 6 Sep 2023
Time: 12:30 PM
Location: PJ
Gideon has a master degree in Complex Adaptive Systems from Chalmers University of Technology.
In his PhD, Gideon will focus his research on deep learning.
Mirja has a Master degree in Physics from the University of Gothenburg.
In her PhD, Mirja will focus on graph neural networks and deep learning.
Dániel Veréb, Mite Mijalkov, Anna Canal-Garcia, Yu-Wei Chang, Emiliano Gomez-Ruiz, Blanca Zufiria Gerboles, Miia Kivipelto, Per Svenningsson, Henrik Zetterberg, Giovanni Volpe, Matthew Betts, Heidi IL Jacobs, Joana B Pereira
eLife 12, RP87188 (2023)
doi: 10.7554/eLife.87188.3
The locus coeruleus (LC) is an important noradrenergic nucleus that has recently attracted a lot of attention because of its emerging role in cognitive and psychiatric disorders. Although previous histological studies have shown that the LC has heterogeneous connections and cellular features, no studies have yet assessed its functional topography in vivo, how this heterogeneity changes over aging, and whether it is associated with cognition and mood. Here, we employ a gradient-based approach to characterize the functional heterogeneity in the organization of the LC over aging using 3T resting-state fMRI in a population-based cohort aged from 18 to 88 years of age (Cambridge Centre for Ageing and Neuroscience cohort, n=618). We show that the LC exhibits a rostro-caudal functional gradient along its longitudinal axis, which was replicated in an independent dataset (Human Connectome Project [HCP] 7T dataset, n=184). Although the main rostro-caudal direction of this gradient was consistent across age groups, its spatial features varied with increasing age, emotional memory, and emotion regulation. More specifically, a loss of rostral-like connectivity, more clustered functional topography, and greater asymmetry between right and left LC gradients was associated with higher age and worse behavioral performance. Furthermore, participants with higher-than-normal Hospital Anxiety and Depression Scale (HADS) ratings exhibited alterations in the gradient as well, which manifested in greater asymmetry. These results provide an in vivo account of how the functional topography of the LC changes over aging, and imply that spatial features of this organization are relevant markers of LC-related behavioral measures and psychopathology.
