Mario Cubero-Campos

Microbial colonization is a major cause of deterioration in paintings, leading to discoloration, pigment degradation, and loss of structural integrity. While biodeterioration of artworks has been studied in temperate climates, tropical environments remain underexplored despite their high humidity and temperature, which can promote microbial growth. This study assessed the microbiological deterioration of two 18 ^th -century oil paintings, La Muerte de San José and Virgen de Guadalupe, located in Orosi’s Colonial Church and Religious Art Museum, Costa Rica. Microorganisms were isolated and identified using VITEK 2, microscopy, and matrix-assisted laser desorption ionization–time of flight mass spectrometry analysis, and their biofilm-forming capacity was evaluated. Additionally, the antimicrobial activity of six essential oil components was tested using direct and indirect contact assays. Seventeen bacterial taxa and 15 fungal genera were identified, with Bacillus , Staphylococcus , Cladosporium , and Aspergillus among the most common. Based on the fungal isolate-frequency distributions, Virgen de Guadalupe had a higher Shannon–Wiener diversity index than La Muerte de San José. Several isolates displayed strong biofilm formation, particularly Bacillus subtilis / amyloliquefaciens / vallismortis , and Staphylococcus saprophyticus . Linalool exhibited the strongest inhibitory activity, achieving complete bacterial growth inhibition in non-contact assays. Short-term environmental monitoring documented daily variation in temperature, relative humidity, and CO ₂ concentration during the 8-day measurement period. Together, these results characterize the culturable microorganisms recovered from two tropical heritage paintings and identify volatile essential oil components as candidates for further evaluation in preventive conservation. IMPORTANCE: Understanding the microbiological deterioration of cultural heritage in tropical environments is crucial for designing sustainable conservation strategies. While microbial colonization of artworks has been widely studied in temperate regions, data from tropical heritage settings remain limited. This study integrates microbiological, environmental, and physicochemical analyses to characterize culturable microorganisms recovered from 18 ^th -century oil paintings in Orosi, Costa Rica. By combining microbial identification, biofilm quantification, and essential oil biocide testing, it bridges applied microbiology and cultural heritage conservation. The in vitro inhibition of biofilm-forming bacteria by volatile compounds such as linalool in a non-contact assay supports further investigation of their potential in conservation, including their efficacy and compatibility with artwork materials. These findings provide a basis for future studies of microbial deterioration in tropical heritage settings and for evaluating conservation applications of volatile compounds.

A bstract: A search for the lepton-flavour-violating decay τ ⁻ → μ ⁻ μ ⁺ μ ⁻ is carried out using data collected by the LHCb experiment between 2016 and 2018 in proton-proton collisions at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb ^{− 1} . An upper limit of 1 . 9 (2 . 3) × 10 ^{− 8} is set at the 90% (95%) confidence level on the branching fraction of the decay.

A bstract: This paper presents the first measurement of the forward-backward asymmetry, A _FB , and the flat term, F _H , that parameterise the angular distribution of the B ⁺ → π ⁺ μ ⁺ μ ⁻ decay. The proton-proton collision dataset used in the analysis corresponds to an integrated luminosity of 9 fb ^{− 1} , collected with the LHCb experiment between 2011 and 2018. The analysis is performed in two intervals of dimuon mass squared, one above and one below the region containing the J/ψ and ψ (2 S ) narrow charmonium resonances. The Standard Model predictions lie within the obtained 68% confidence level interval in the high-mass and within the 99% interval in the low-mass region.

The first observation of the doubly charmed baryon Ξ c c + is reported through its decay to the Λ c + K − π + final state, with a statistical significance exceeding seven standard deviations. The observation is made using proton-proton collision data collected in 2024 with the LHCb Run 3 detector at a center-of-mass energy of 13.6 TeV, corresponding to a total integrated luminosity of 6.9 fb − 1 . The Ξ c c + mass is measured to be 3619.97 ± 0.83 ± 0.26 − 1.30 + 1.90 MeV / c 2 , where the first uncertainty is statistical, the second is systematic, and the third is due to the unknown Ξ c c + lifetime, which is assumed to lie in the range 15–160 fs with a baseline value of 45 fs. The difference between the masses of the Ξ c c + and Ξ c c + + baryons is determined to be − 1.77 ± 0.84 ± 0.15 − 1.30 + 1.90 MeV / c 2 . This is the first observation of a new particle made with the LHCb Run 3 detector.

A flavor-tagged time-dependent analysis of B 0 → K S 0 μ + μ − decays is performed across the full dimuon mass range excluding the J / ψ and ψ ( 2 S ) resonance regions. The analysis uses proton-proton collision data collected by the LHCb experiment in 2011–2018 at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb − 1 . The C P violation parameters are determined to be C = − 0.13 ± 0.32 ± 0.04 , S = + 0.82 ± 0.29 ± 0.05 , where the first uncertainties are statistical and the second are systematic. The results are consistent with the standard model prediction. This is the first experimental study of time-dependent C P violation in b → s ℓ + ℓ − processes.