Rudjer Boskovic 研究所

Key physicochemical parameters of Plitvice Lakes water were monitored over a three-year period at representative locations along the lake system. In situ tufa mineralization rates were determined by using glass substrates, revealing a pronounced downstream increase: the lowest rates occurred at the lake's source, while the highest were measured in the lake's outflow to Korana River. Strong seasonal patterns were also evident, with maximum deposition rate during summer. In situ-formed tufa consisted predominantly of calcite and magnesium calcite, while small amounts of the metastable polymorph vaterite were occasionally detected during early mineralization stages. Diatom frustules were consistently present in all samples, highlighting the interconnected roles of biotic and abiotic factors, including hydrodynamics, temperature, and water chemistry, in regulating tufa formation. Field observations were complemented by laboratory calcium carbonate precipitation experiments conducted in artificial karst water formulated to mimic the properties of Plitvice Lakes. Structural, morphological, and chemical comparisons showed excellent agreement between natural tufa and laboratory-precipitated calcium carbonate. These results demonstrate the suitability of the proposed experimental model system for future laboratory studies aimed at disentangling the environmental and anthropogenic controls on tufa formation.

Murunskite (K2FeCu3S4) is a layered sulfosalt chalcogenide that occupies a unique position between the cuprate and iron pnictide families: it shares electronic characteristics with the former and adopts the crystal structure of the latter. Despite a completely random distribution of magnetic Fe within a nonmagnetic Cu matrix, murunskite exhibits a well-defined quarter-zone antiferromagnetic transition at 97 K and complete orbital order below 30 K. These findings reveal the unexpected emergence of long-range order in a high-entropy-like environment. This inherent robustness to site disorder in a layered structure makes murunskite a paradigmatic system for further studies. Here, we investigate doping strategies in murunskite to assess how its electronic and magnetic properties can be tuned. Using melt-growth techniques, we achieve substitutions at the magnetic metal site (Fe), spacer cation (K), and sulfur ligand (S), which significantly influence transport and magnetic properties. In addition, we use ionic-liquid gating on the parent compound and observe a gate-dependent suppression of resistivity, confirming the potential for electrostatic control over transport. Our results demonstrate the chemical and electronic plasticity of murunskite, offering a valuable platform for co-engineering disorder, magnetism, and transport, and opening avenues to explore quantum phenomena in correlated and high-entropy materials.

This research highlights a fascinating parallel between the Megaparsec-scale cosmic web in space and a laboratory-created micro-scale particle web in laser plasma. We show that similar filamentary web structures on drastically different scales evolve from nonlinear-far from equilibrium - different physical processes. While the cosmic web is created by the gravitational collapse of dark matter and aggregation into galactic clusters, strings-filaments and voids, a microparticle web is created by the Brownian motion and aggregation of metal-oxide particles. Spatial intermittency - resulting from intermittent velocity and density fields-characterizes multifractal microparticle web as a mimic of the cosmic multifractal web. Based on selfsimilar hierarchical clustering of matter, the underlying processes create both webs with a (non-Gaussian) power law distribution of the particle number density, and of the cosmic matter density. This study reveals that variation of the metal-oxide microparticle density in the strings-resembles the large density variations of massive halos in the galactic filament-strings. Cantor set distribution of metal-oxide microparticle separation-intervals along the strings-mimics the Cantor set distribution of the intervals of mass sticking along the intergalactic filaments that connect galaxy clusters.

We introduce the first-order noncommutative (NC) corrections to the general nonlinear electrodynamics (NLE) Lagrangian depending on two electromagnetic invariants. The NC deformation of Einstein-NLE theory is implemented using the $\partial_t\wedge\partial_φ$ Drinfel'd twist and the NC effects are encoded in the matter sector through the Seiberg-Witten map. The resulting equations of motion reflect two distinct sources of nonlinearity in this framework; one arising from replacing Maxwell's electrodynamics with its nonlinear modifications and another from the NC deformations. Assuming a general form of static, spherically symmetric dyonic black hole as a seed solution in the commutative limit, we solve the equations of motion perturbatively to the first order in the NC parameter $a$. Finally, we evaluate the obtained corrections to the metric tensor and gauge potential for several prominent NLE theories.

In particle physics the world is described by a function, the Lagrangian. Each of its sectors characterizes the interactions between the particles of the Standard Model (SM). The addition of hypothetical new particles is done by including new terms in the Lagrangian. The scalar or Higgs sector of the SM is built with only one scalar complex field and it is extended by including new spin zero fields. This can help to solve questions that cannot be answered by the SM alone, like introducing dark matter candidates or new sources of CP-violation required to explain the matter-antimatter asymmetry of the universe. The corresponding theories have to be probed experimentally. For the high energy region, the standard tools are collider experiments such as the Large Hadron Collider, or other possible future facilities. Dark matter experiments scrutinize the connection between the visible and the dark world.