Włodzimierz Trzebiatowski Institute of Low Temperature and Structure Research

Posttranslational modifications of human enzymes play a crucial role in disease development. 4‐hydroxynonenal (4‐HNE), a lipid peroxidation product, can modify proteins and disrupt their function. Human cytochrome CYP4F11, involved in lipid metabolism and xenobiotic degradation, was previously shown to be inhibited by 4‐HNE in a malaria model, where hemozoin‐induced 4‐HNE formation occurs in monocytes. However, structural changes to CYP4F11 upon 4‐HNE modification had not been described. In this study, we investigated these changes using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and Raman spectroscopy. DSC thermograms revealed an increased energetic barrier to unfolding, suggesting structural reorganization. FTIR data, supported by computational analysis, showed a decrease in alpha‐helix content (0.2–2.5%) and an increase in beta‐structure (2.2–3.3%), along with altered disordered regions. Raman spectroscopy indicated significant changes in luminescence decay across emission wavelengths. These structural alterations induced by 4‐HNE conjugation (protein lipoxidation) may significantly influence the enzymatic activity of CYP4F11, with potential implications for lipid metabolism and xenobiotic detoxification.

The effect of the partial pressure of hydrogen on the reduction processes in CeO2 nanoparticles was investigated. The surface reducibility of CeO2 upon exposition to 0.01–5 mbar and 5–402 mbar of H2 was investigated by NAP-XPS and H2-TPR techniques, respectively. Special attention was focused on studying the role of partial pressure of H2 (ranging from 5 to 402 mbar in the input gas mixture) on the H2-TPR profile. The effect of H2 partial pressure on the course of surface and bulk reduction of CeO2 was shown and discussed.

Spiropyrans exhibit reversible photochromism that strongly depends on solvent polarity; yet a quantitative understanding of this relationship remains incomplete. Here we combine detailed spectroscopic and kinetic experiments with ab initio calculations to investigate 5’-methoxy-1',3',3'-trimethyl-6-nitrospiro[chromene-2,2'-indoline] (SP). Ultraviolet irradiation at 368 nm populates the S3 (1ππ*) state, initiating the ring-opening reaction to the merocyanine (MC) form, which is subsequently followed by thermal ring-closing. Theoretical calculations indicate that photoexcited SP undergoes nonradiative relaxation to the S₁ charge-transfer state, from which the system reaches the ground state via a ring-opened conical intersection. Experimental kinetics studies have revealed that increasing solvent polarity slows relaxation and raises the activation energy from 89.7 kJ mol⁻1 in dioxane to 104.6 kJ mol⁻1 in acetone. Calculations have reproduced this trend, showing that polar solvents preferentially stabilize MC over the transition state. The observed blue shift of the MC absorption band with increasing polarity confirms the presence of negative solvatochromism. This combined experimental-theoretical analysis provides a quantitative framework linking solvent polarity, photochromic efficiency, and the activation energy in a model nitrospiropyran system.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-29654-3.

In the aspect of water purification, a photoactive hybrid material based on reduced graphite oxide (RGO) with covalently, coordinatively, and through van der Waals interactions bonded zirconium(IV) phthalocyanine (PcZr) is proposed. In the material, the phthalocyanine complex plays the role of photosensitizer, while RGO is considered a carrier, ensuring high surface area and supporting PcZr activation. The central metal atom of PcZr directly interacts with lateral active oxygen-containing surface groups of graphite oxide, mainly –OH and –COOH. Thus, the proposed method of synthesis under solvothermal conditions allowed obtaining a relatively high concentration of the dye (0.2 wt.%) in the system based on a partially reduced and exfoliated graphite oxide. Optical studies confirmed the presence of PcZr through absorption and luminescence spectra. Additionally, effective generation of reactive oxygen species was demonstrated by testing the transformation of a dye indicator (diphenylisobenzofuran). Photocatalytic activity of the system was confirmed by photooxidizing selected organic dyes (methylene blue, Rhodamine B, Brilliant Green, and Eriochrome Black T) in a water medium, tested in slightly acidic conditions under red light. The greatest overall decrease in absorption during the photodegradation test was observed for Brilliant Green, reaching 88% after 3 h of irradiation.

Temperature metrology plays a pivotal role in fundamental science and applied technologies. This article explores the evolution of low-temperature thermometry, paying special attention to the redefinition of the kelvin through the Boltzmann constant. The article outlines the historical and contemporary contributions of the Temperature Standards Laboratory at Institute of Low Temperature and Structure Research of PAN. The laboratory has been instrumental in developing precise calibration methods and participating in international comparisons. Additionally, the paper discusses the implementation of the ITS-90 scale and the use of fixed-point cells, as well as the laboratory’s involvement in European metrology initiatives. These efforts highlight the interdisciplinary nature of temperature measurement and its critical importance in various scientific and industrial fields.

The magnetic ground state and electronic structure properties of solid solutions EuFe2–xNixAs2 (x = 0, 0.08, 0.12, 0.20, 0.40, 2.0) are investigated using the full-potential linearized augmented-plane wave method. The results show that Ni substitution has a robust influence on the structural, magnetic ground state, and electronic properties of EuFe2As2. When 10% of Ni is substituted for the Fe atoms, orthorhombic-tetragonal distortion is observed. Simultaneously, as the Ni concentration increases, the density of states (DOS) at the Fermi level (EF) decreases implying that the electronic state becomes more stable. In alloys with x = 0.20, 0.40, the partial DOS of both Eu and Fe, as well as their strong spin polarization, show a dominant contribution around EF. For x > 0.12, there is a stronger interband scattering, as evidenced by a large number of electronic band crossing EF. The multi-sheet structure is revealed by the Fermi surface topologies in all compounds. The electron localization functions show metallic and covalent bonds in EuFe2As2, EuFe1.6Ni0.4As2, and EuNi2As2 with bonds in EuFe2As2 being the most covalent.

The paper presents the results of the influence of SiC dopant, annealing temperature, and annealing time on the morphology of MgB2 material in superconducting wires. The results of measurements of critical temperature (Tc), irreversible magnetic field (Birr), resistance in the normal state (Rn), and transport critical current density (Jct) at the temperature range from 15 K to 30 K are presented. The MgB2 material is characterized by the presence of two specific regions. The first region with high density, excess Mg, and rectangular MgB2 grains is located outside the voids surrounding them. The second region occurs inside the ceramic core, away from voids, and its chemical composition corresponds to a stoichiometric Mg to B ratio (1:2), and it is characterized by the presence of spherical grains and lower material density. A higher amount of SiC admixtures (6 at.%) causes an increase in the first region surface area. This kind of structure observation in MgB2 superconducting wires has never been reported previously. The transport measurements showed that higher SiC dopant leads to lower Jct at higher temperatures and high magnetic fields. The studies showed that the point-dominant mechanism and the first region allow for obtaining high Jct at 30 K.