Most Prominent Research Achievements in 2017

University of Ljubljana every year traditionally opens the University Week with the presentation of the most prominent research achievements. The purpose of the event is to emphasize the university’s focus on research and to present those researchers who achieved especially visible results this year.

When selecting the creators of the ten most prominent research achievements of the University of Ljubljana, the commission primarily takes into account international prominence, which is evident from quotations and the influence of the journal in which the work was published. Also affecting the selection are the completed entirety of the achievement, the interest to the wider expert and general public and the benefits of its use.

List of the ten most prominent research achievements of the University of Ljubljana in 2017:

1. Breakthrough Discovery: An Early Mechanical Coupling of Planktonic Bacteria in Dilute Solutions

The fundamental discovery in the field of natural science about mechanical couplings between bacteria, previously considered non-existent, changes the way of looking at microorganisms, understanding bacterial co-operation and the impact of bacteria on the environment.
 

Authors: Simon Sretenović, Biljana Stojković, Iztok Dogša, Rok Kostanjšek, Igor Poberaj, David Stopar
 

A group of researchers from the Biotechnical Faculty of the University of Ljubljana, together with their associates from the Faculty of Medicine and the Faculty of Mathematics and Physics of the University of Ljubljana (Simon Sretenović, Biljana Stojković, Iztok Dogša, Rok Kostanjšek, Igor Poberaj in David Stopar), discovered mechanical couplings between bacteria that were previously considered by researchers to be non-existent, thereby rejecting the centuries-old dogma about unrelated planktonic bacterial cells. The fundamental discovery in the field of natural science changes the way of looking at microorganisms, understanding bacterial co-operation and the impact of bacteria on the environment.

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2. New Computational Method for Seismic Retrofitting of Historic Masonry Structures with the Use of Base Isolation

Researchers from the Faculty of Architecture of the University of Ljubljana proposed a novel approach of computational modelling of the response of masonry structures to seismic actions and the method for the selection of a proper type of base isolation devices for installation into cultural and historic buildings.


Authors: Simon Petrovčič, Vojko Kilar


With the use of conventional restoration construction techniques in historic masonry buildings we can achieve a high level of seismic safety, but such measures are also highly invasive and demand relatively intensive interventions in the building, and as a consequence also affect the building’s historical and cultural substance. In seismic-prone areas around the world, seismic base isolation is also employed in certain cases. The basic functional principle of such a system is that by increasing the period of vibration and damping of the coupled system the level of forces generated on the structure during seismic actions is greatly reduced. For this purpose, special bearings, which are usually installed at the level of the structure’s foundations, are used. This means that in such cases large-scale interventions in the building are limited. In this context, the use of the seismic base isolation in historic masonry structures is a unique solution because it provides increased seismic resistance by reducing seismic forces on the building. The complexity of the installation of such devices and a relatively high price limit its implementation to the most valuable cultural heritage buildings.

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3. Absorptive Capacity of Domestic Firms is Crucial for Knowledge Spillovers from Foreign-Owned to Domestic Firms

Absorptive capacity for knowledge spillovers in domestic firms depends mainly on the level of technological development, research and development as well as on the innovation activity, level of development of human capital, productivity level and/or export orientation.


Authors: Matija Rojec, Mark Knell


The authors (Matija Rojec of the Faculty of Social Sciences of the University of Ljubljana and Mark Knell of the NIFU Nordic Institute for Studies in Innovation Research and Education) analyse the latest substantive and methodological contributions to knowledge spillovers analysis from foreign direct investment (FDI), which has brought some more optimistic results as far as FDI spillovers are concerned and can help in further development of this field of research. The findings were published in the academic Journal of Economic Surveys.

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4. New Method for Bandgap Imaging in Photovoltaic Modules

New Method for Bandgap Imaging in Photovoltaic ModulesIn manufacturing, the method enables quality control and early detection of changes in the production process, and in research, the method enables detecting non-homogeneity and the possibility to optimize the processes of applying thin layers of semiconductors, which are an active part of solar cells.


Authors:
Matevž Bokalič, Marko Topič, Bart E. Pieters, Andreas Gerber, Uwe Rau


The research group at the Faculty of Electrical Engineering of the University of Ljubljana (Matevž Bokalič, Marko Topič), in cooperation with the Forschungszentrum Jülich Institute (Bart E. Pieters, Andreas Gerber, Uwe Rau), developed a unique method for absorber bandgap imaging in photovoltaic modules with variable stoichiometry. The method is based on the appearance of luminescence, where the optoelectronic element emits light under the effect of excitation. The light is captured in two or several different spectral regions, where different cameras with different spectral responses can be used. On the basis of the calibration relation and the ratio of captured images, the absorber bandgap is determined – EG (xy) – throughout the surface of the photovoltaic module. The advantage of the new method is an extremely fast determination of absorber bandgap across the surface of the photovoltaic module, which the existing method did not deliver. The speed and non-destructiveness of the method enable in-situ use in the industrial environment as well as in research. In the production context, it enables quality control and early detection of changes in the production process, whereas in research, it enables detecting non-homogeneity and provides the possibility of optimizing the processes of applying thin layers of semiconductors, which are an active part of solar cells.

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5. A mechanism for the Survival of Bacteria in the Presence of Antibiotics Explained

Researchers from the Faculty of Chemistry and Chemical Technology of the University of Ljubljana, in cooperation with Belgian researchers, were the first to explain a molecular mechanism governing the regulation of the toxin-antitoxin module, which explains how and why bacterial cells stop their growth and development.


Authors:
San Hadži, Igor Drobnak, Andrej Mernik, Črtomir Podlipnik, Remy Loris, Jurij Lah


Survival of bacterial cells in presence of antibiotics represents a significant problem for treatment bacterial infections. Such cells tolerate antibiotics either because they acquire specific mutations (changed genotype – resistance) or because they can switch into the metabolically calm, dormant state (changed phenotype – persistence). When the concentration of an antibiotic drops, the bacteria “wake up” and resume multiplying, which results in many recurrent and chronic diseases. It is well-known that bacterial cells can halt their metabolism using their own genetic systems, called toxin-antitoxin modules. The researchers from the Faculty of Chemistry and Chemical Technology of the University of Ljubljana (San Hadži, Igor Drobnak, Andrej Mernik, Črtomir Podlipnik, Jurij Lah), in cooperation with Belgian researchers (Remy Loris laboratory), were the first to explain the molecular mechanism governing the regulation of the toxin-antitoxin module, which explains how and why bacterial cells can stop their growth and development. 

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6. Bronze-Mean Hexagonal Quasicrystal

Primož Ziherl from the Faculty of Mathematics and Physics of the University of Ljubljana and Tomonari Dotera and Shinichi Bekku from the Kindai University in Osaka published an article in the renowned journal Nature Materials, in which they propose a two-dimensional quasicrystal based on the bronze mean and characterized by six-fold symmetry.


Authors:
Primož Ziherl, Tomonari Dotera, Shinichi Bekku


This type of quasicrystal formation is interesting because it complements the Penrose and Ammann-Beenker tiling based on the gold or silver mean, respectively, and because it emphasizes  that quasicrystalline order does not necessarily have a forbidden rotational symmetry. In this sense, the paper is a significant theoretical step forward in the field of quasicrystals, which is also important from the experimental perspective.

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7. A Novel Performance Evaluation Methodology for Single-Target Trackers

Researchers from the Faculty of Computer and Information Science of the University of Ljubljana created a rigorous methodology for the analysis of trackers and a methodology for systematic determination of the test database with a large descriptive power, and with the intention to expand the impact of proposed methodologies they established the initiative VOT Challenge, which experienced outstanding support in the community.


Authors:
Matej Kristan, Aleš Leonardis, Luka Čehovin Zajc


Visual tracking of objects is a rapidly evolving field with a wide range of applications that extend from video surveillance systems to autonomous robots. Tens of new approaches are annually published only on high-profile Conferences on Computer Vision, while the lack of a standardized tracker analysis methodology hinders a clear overview of the development of the respective field.

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8. Efficient Water Disinfection by Hydrodynamic Cavitation

Researchers from the Faculty of Mechanical Engineering of the University of Ljubljana and the National Institute of Biology were the first in the world to show the possibility of the inactivation of viruses by hydrodynamic cavitation – rapid vaporization and recondensation of water as a result of sudden local change in pressure.

Authors: Janez Kosel, Ion Gutierrez-Aguirre, Tanja Dreo, Nejc Rački, Maja Ravnikar, Matevž Dular


The aim of water treatment is to reduce pathogenic microorganisms to the extent where they are no longer harmful to our health. The standard water disinfection procedures are problematic in terms of energy and the environment. As the first in the world, the researchers from the Faculty of Mechanical Engineering of the University of Ljubljana (Janez Kosel, Matevž Dular) and the National Institute of Biology (Ion Gutiérrez-Aguirre, Nejc Rački, Tanja Dreo, Maja Ravnikar) under the mentorship of Matevž Dular showed the possibility of the inactivation of viruses by hydrodynamic cavitation – rapid vaporization and recondensation of water as a result of sudden local change in pressure. 

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9. Computational Models of Liver Metabolism: How Far from the Clinics?

Even though the majority of metabolic models has great potential clinical value, either as a diagnostic tool for identifying new drugs or as a tool for the establishment of personalised therapy, their clinical applications are still limited.


Authors:
Tanja Cvitanović, Matthias C. Reichert, Miha Moškon, Miha Mraz, Frank Lammert, Damjana Rozman


Computational models have become indispensable in explaining the dynamics of complex systems, such as the human body and its organs. Such models can also be applied to understanding metabolism, which is fundamental for effective diagnosis and treatment of liver related diseases as well as in understanding drug metabolism. This knowledge can be obtained with systems biology/medicine approaches that account for the complexity of hepatic responses and their consequences in other organs.

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10. A Potential for Cancer Diagnosis and Treatment

Multifunctional mesoporous gadolinium-enriched TiO2 microspheres can be simultaneously used for cancer diagnosis and treatment.
 

Authors: Roghayeh Imani, Ralf Dillert, Detlef W. Bahnemann, Meysam Pazoki, Tomaž Apih, Veno Kononenko, Neža Repar, Veronika Kralj-Iglič, Gerrit Boschloo, Damjana Drobne, Tomas Edvinsson, Aleš Iglič
 

Gadolinium-enriched TiO2 microspheres (beads) possess controlled multifunctional properties. Mesoporous semiconductor TiO2 microspheres were enriched with gadolinium to improve their photoluminescence functionality and to make them applicable in optical and magnetic resonance imaging (MRI) due to improved  spin relaxation for  MRI. Additional applicability stems from the enhanced generation of reactive oxygen species (ROS) under UV-A light irradiation. Gadolinium-enriched microspheres were integrated into MG-63 osteosarcoma cell lines, which means they are biocompatible. The principal advantage of the use of gadolinium-doped TiO2 microspheres is the possibility of their simultaneous use for cancer diagnosis (MRI) and treatment (ROS production upon UV irradiation). Namely, doped TiO2 microspheres can be simultaneously used both for locating cancer cells (i.e. diagnostics via MRI) as well as for killing cells (i.e. therapy), which is the result of the formation of ROS when TiO2 microspheres in cancer tissue are exposed to UV light. The essential concept here is that cancer cells and normal cells have different dynamics of accepting TiO2 microspheres. Cancer cells accept them faster (more) than healthy cells, which is fatal for cancer cells once exposed to UV-A light.

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