An experimental study of the magnetocaloric effect in tetraaquabis(hydrogen maleato)nickel(II), [Ni(C₄H₃O₄)₂(H₂O)₄] powder sample is presented. The magnetocaloric properties of the studied sample were investigated using specific heat and magnetization measurements in magnetic fields up to 9 T in the temperature range from 0.4 to 50 K. A large conventional magnetocaloric effect was found at a temperature of about 3.5 K, where −ΔS_M = 8.5 Jkg⁻¹K⁻¹ and 11.2 Jkg⁻¹K⁻¹ for a magnetic field of 5 T and 7 T, respectively. Assuming a substantial role of the crystal field, the temperature dependence of the magnetic specific heat in a zero magnetic field was compared with an S = 1 model with single-ion anisotropy parameters D and E (axial and rhombic). The best agreement was found for the parameters D/k_B = −7.82 K and E/k_B = −2.15 K. On the other hand, the experimental temperature dependence of −ΔS_M shows higher values compared to the theoretical prediction for the mentioned model, indicating the presence of additional factors in the system, such as an exchange interaction between magnetic ions. The first exchange pathway can be realized through maleic rings between the nearest Ni(II) ions. The second exchange pathway can be realized through water molecules approximately along the a crystallographic axis. Broken-symmetry DFT calculations performed using the computational package ORCA provided the values of ferromagnetic exchange interactions, J₁/k_B = 1.50 K and J₂/k_B = 1.44 K (using B3LYP functional). The presence of such ferromagnetic correlations in the studied system may explain the enhanced magnetocaloric effect compared with the model of an anisotropic spin-1 paramagnet.

The fungi of the genus Ophiocordyceps sinensis (Berk.) belong to entomopathogenic fungi. Ophiocordyceps sinensis has been used as a tonic and medicinal product in China for more than 2,000 years. A number of scientific papers have described the clinical use of this parasitic fungus with subsequent biological and pharmacological effects. The various chemical compounds identified in these fungi are responsible for a wide range of biological activity: cordycepin, cordycepic acid, D-mannitol, polysaccharides, nucleotides, proteins, amino acids, and unsaturated fatty acids. Our research focused on the determinations of the biologically active chemical compounds in extracts from cultivated Ophiocordyceps fungi using UV/VIS (Ultraviolet/Visible) spectrophotometry and NMR (Nuclear Magnetic Resonance) spectroscopy. The testing of antimicrobial activity of extracts against the collection strains of Escherichia coli and Staphylococcus aureus demonstrated that the percentage of RIZD (relative inhibition zone diameter) ranged from 83 % to 166 %. The increased antimicrobial activity against E. coli was observed in comparison with that against S. aureus.

Mushrooms from the genus Cordyceps are characterized by a wide range of biological effects due to the diverse amount of substances contained in them and are an important source of bioactive compounds. In China, mushrooms of the genus Cordyceps have been used as a medicinal preparation of traditional Chinese medicine for centuries. So far, a considerable number of studies have been conducted that focused on analyzing the effects of Cordyceps , which include their antioxidant, antibacterial, immunomodulatory, antidiabetic, antitumor, and many other effects. The ability of fungi to form complexes with various metals is also interesting. It is believed that polysaccharides are the main component of the extracts involved in the complexation with metals, after which their biological effects are improved and deepened. The work deals with the comparison of the antioxidant and antibacterial effects of Cordyceps extracts with extracts of this mushroom enriched with silver ions. Based on scientific studies, it is assumed that there is a complexation between the chemical compounds of the extracts and silver.

Natural Ophiocordyceps sinensis is a highly valued medicinal fungus known for its antitumor, immunomodulatory, and antiviral properties. Due to extensive overharvesting in Asia, cultivated alternatives have become increasingly important. This study aimed to evaluate the biological activity and chemical composition of extracts obtained from cultivated Ophiocordyceps sinensis grown using different rice substrates. Methanolic extracts were prepared from solid-state cultivated Ophiocordyceps sinensis grown on Oryza sativa var. indica and Oryza sativa var. japonica. Antioxidant activity was determined using the DPPH assay, while proteolytic activity was evaluated with the azocasein substrate. Chemical characterization of major compounds was performed using ¹D and ²D NMR spectroscopy, together with IR spectroscopy. UV/Vis spectrophotometry was employed to confirm the formation of silver nanoparticles in AgNO₃ solution. Antimicrobial activity was tested against bacterial strains, including Escherichia coli and Staphylococcus aureus. All prepared methanolic extracts exhibited measurable antioxidant and proteolytic activities. The dominant identified compounds were Z-oleic acid, linoleic acid, and D-mannitol. Selected extracts successfully induced the formation of silver nanoparticles. The highest antimicrobial activity against Escherichia coli was observed for sample 1OS, reaching a mean % RIZD value of 129.32 ± 0.58%.