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This paper investigates the oil on canvas painting Boat scene (1974) by Liu Kang (1911–2004), belonging to the National Gallery Singapore (NGS). The focus is on disfiguring paint protrusions in a specific area and colour in the composition. Moreover, in search of the possible factors responsible for the creation of the protrusions, the structure and composition of the paint layers were determined. Three possible reasons were put forward to explain this phenomenon: deliberate textural effects, the expansion of metal soaps and unintentional paint contamination during the artistic process. Investigative techniques such as technical photography, digital microscopy, optical microscopy (OM), polarised light microscopy (PLM), field emission scanning electron microscope (FE-SEM-EDS) and attenuated total reflectance micro-Fourier transform infrared spectroscopy (ATR μ-FTIR) were employed to analyse paint layers, including protrusion samples. The analyses revealed that the protrusions resulted from an unintentional contamination of the oil paint during the artistic process by dry fragments of different pigment mixtures bound in drying oil. Zinc soaps were found in significant concentrations within the protrusions and other parts of the painted scene. Nevertheless, the metal soaps do not pose a direct risk to the integrity of the paint layers at the time of this research. The analyses highlight the potential challenges caused by the protrusions that conservators may face while caring for the painting. The research contributes to our ongoing comprehension of the artist’s working process.

This paper investigates the oil on canvas painting Boat scene (1974) by Liu Kang (1911–2004), belonging to the National Gallery Singapore (NGS). The focus is on disfiguring paint protrusions in a specific area and colour in the composition. Moreover, in search of the possible factors responsible for the creation of the protrusions, the structure and composition of the paint layers were determined. Three possible reasons were put forward to explain this phenomenon: deliberate textural effects, the expansion of metal soaps and unintentional paint contamination during the artistic process. Investigative techniques such as technical photography, digital microscopy, optical microscopy (OM), polarised light microscopy (PLM), field emission scanning electron microscope (FE-SEM-EDS) and attenuated total reflectance micro-Fourier transform infrared spectroscopy (ATR μ-FTIR) were employed to analyse paint layers, including protrusion samples. The analyses revealed that the protrusions resulted from an unintentional contamination of the oil paint during the artistic process by dry fragments of different pigment mixtures bound in drying oil. Zinc soaps were found in significant concentrations within the protrusions and other parts of the painted scene. Nevertheless, the metal soaps do not pose a direct risk to the integrity of the paint layers at the time of this research. The analyses highlight the potential challenges caused by the protrusions that conservators may face while caring for the painting. The research contributes to our ongoing comprehension of the artist's working process. [ABSTRACT FROM AUTHOR]

Zinc (Zn) is essential for optimal plant growth and nutrition, while zinc-solubilizing bacteria (ZSB) enhance plant accessibility to zinc by converting its insoluble forms into usable ones. The primary objective of this research was to isolate and identify Zn-solubilizing strains from the onion rhizosphere and evaluate their ability to solubilize different insoluble Zn compounds, including ZnO, ZnCO3, and Zn3(PO4)2. Of the nineteen bacterial isolates retrieved, fifteen demonstrated the ability to solubilize inorganic Zn compounds based on plate assay techniques. The Zn-solubilizing bacterial strains, selected for their qualitative properties, underwent quantitative testing in broth culture using atomic absorption spectrophotometry (AAS) and Field Emission-Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (FE-SEM-EDS). Seven bacterial isolates with a high capacity to solubilize Zn were identified based on 16S rRNA gene amplification and sequence analysis. These isolates were affiliated with Pantoea eucrina, Pantoea dispersa, Pseudomonas aeruginosa, Bacillus velezensis, and Pseudomonas fluorescens. Notably, this study is the first to report the potential of Pantoea eucrina as a ZSB. The strain Pantoea eucrina ZSC9 exhibited the maximum Zn solubilization index (8.85) and the highest soluble Zn content (624 mg L−1) among the three insoluble Zn compounds, with ZnO being the most effectively solubilized on the 10th day of incubation in ZnO-enriched basal medium. All bacterial isolates were more effective at solubilizing ZnO than ZnCO3 and Zn3(PO4)2, and this solubilization led to a significant drop in the pH of the broth. Pantoea eucrina ZSC9 showed the maximum pH reduction (3.82) in a ZnO-supplemented medium, indicating a negative correlation between broth pH and Zn solubilization. Seven selected ZSB strains were assessed for their potential to enhance onion growth under pot house conditions. The results showed that inoculating onion seedlings with these ZSB strains significantly improved their growth. Among the strains tested, ZSC9, ZSC10, and ZSC17 were the most effective, enhancing growth attributes such as plant height, bulb diameter, fresh and dry weight of bulbs, Zn uptake by the plant, and overall bulb yield compared to other strains. These findings suggest that these ZSB isolates have great potential as biofertilizers to enhance plant growth and development.