Microorganisms possess the capability to impact virtually any form of cultural heritage, leading to contamination, degradation, and even combined degradation, where diverse microorganism communities facilitate the decay of wooden materials. This study aims to analyze the microbial diversity of the wooden structure bridge at the Shahe Ancient bridge site in Xi'an. The objective is to investigate the correlation between microbial species and the state of wood degradation, as well as explore the relationship between wood microbial species and the potential influence of the wood preservation environment on its long-term preservation. Simultaneously, the conventional laboratory separation technique was employed to isolate the microorganisms that were contaminated by experimental ancient wood. This was done to assess the inhibitory effect of two fungicides on the dominant microorganisms found in ancient wood, identify the most effective inhibitor, and subsequently establish an experimental foundation for safeguarding ancient bridge wood structures. The primary objective of this research was to establish microbial control criteria for the enduring conservation of historical sites, while also equipping conservators with scientifically-guided data to inform future research and restoration endeavors. Graphical Abstract

Cracks are one of the most common issues affecting colored pottery relics; these can be divided into macroscopic cracks, recognizable by the human eye, and micron cracks, which cannot be observed by the naked eye. The gradual development of micron cracks eventually leads to large-scale cracks and the shedding of the coating layer. The repair of such micron cracks poses a key technical difficulty in restoring painted pottery remnants from the Western Han Dynasty. We attempt to solve this problem by reporting on a method that entails the use of a water-borne fluoropolymer material as the adhesive agent, as well as ultra-depth-of-field, digital microscopic imaging technology to build an operating platform for an optical imaging monitoring system. By making simulated ceramic samples, we systematically investigated the influences of water-borne fluoropolymer on chromaticity, adhesion, contact angle, surface morphology, and thermal stability of the paint layer. The results indicate that the color of the painted layer, when treated with the water-borne fluoropolymer, did not change, and the adhesion and contact angle of the painted layer were improved. Additionally, the outcomes of the SEM analysis show that the adhesion and hydrophobicity of the painted layer were improved because the water-borne fluoropolymer filled up the porous structure of the painted layer and covered the pigment particles. These findings demonstrate that aqueous, water-borne fluoropolymer can be used as an adhesive agent for micron cracks. Meanwhile, via the operating platform of the optical imaging monitoring system, the micron cracks of the painted terracotta warriors and horses from the Western Han Dynasty were successfully repaired using the water-borne fluoropolymer. The results imply that the microstructure, size, and geometric spaces of the cracks can be obtained directly utilizing microscopic imaging technology. The dynamic monitoring and imaging system described above can be employed to assist prosthetists in visualizing micro-repair operations in real time, assist with fine visual operations during the repair process, and realize dynamic video recording of the entire repair process. Our work provides a simple visualization method to repair micron-scale cracks in painted pottery relics by applying modern fluoropolymer and ultra-depth-of-field digital microscopic imaging technology.

In this research, the caisson painting of Dayu Temple in Hancheng, Shaanxi, China, was analyzed via a multi-analytical methodology, using a pH meter, an ultra-depth-of-field optical microscope, a scanning electron microscope-energy dispersive spectrometer (SEM-EDS), a high-resolution X-ray diffractometer (XRD), a micro-confocal laser Raman spectrometer, a gas chromatography mass spectrometer (GC-MS), and X-ray fluorescence spectroscopy (XRF). With the corroborative evidence derived from the above analyses, it could be determined that the caisson painting of Dayu Temple was painted on bamboo paper and attached to hemlock wood substrate of the Pinaceae Tsuga genus using starch paste, with common colorants such as carbon black, cinnabar mixed with a small amount of red lead, ultramarine, and ultramarine mixed with Paris green, with animal glue having been adopted as a sizing agent. These results provide important scientific data for the production craft of precious caisson paintings, contributing to the revelation of their historic, artistic, and scientific value, and should enable conservators to make informed decisions in restoration.

Three-dimensional laser scanning technology can be used to quickly, efficiently, and accurately obtain spatial three-dimensional information of cultural relics without contacting the target during the scanning process. The results of this study showed that the extraction of human bones from the Shenna ruins via the auxiliary application of three-dimensional scanning technology reduced human intervention and destruction on the site compared with the traditional archaeological human bone packaging and extraction work method. When combined with the application of three-dimensional scanning technology, the original data information extracted on the spot were more comprehensive and accurate. Additionally, the technology provided us with important scientific data which can be used to discuss the phylogenetic composition of the ancient Qiang people in the settlement village, as well as a new applications of ideas for three-dimensional laser scanning technology usage in the field extraction of cultural relics. However, a follow-up study is needed to improve the comparisons of its applications, providing a conventional auxiliary means for cultural relic extraction and a technical means for cultural relic protection evaluation.

In this study, the Chairman MAO iron statue in Qinghai, China was analyzed via multi-analytical methodology, including polarizing microscope, SEM-EDS, metallographic analysis, high-resolution X-ray diffractometer, ion chromatographic analysis, silver nitrate titration detection in rust samples. The iron cultural relics are affected by factors such as their chemical composition, metallographic structure and surface characteristics, casting process, and natural storage environment. Although the corrosion rate is different, the corrosion is inevitable. With the corroborative evidence derived from the above analyses, it could be determined that the long-term preservation of cast iron statues in outdoor natural environments is prone to oxidation and corrosion, which due to the poor air circulation inside the statue of Chairman Mao Zedong, the humidity is significantly higher than that of the outside. In addition, due to the large temperature difference between day and night in this area, the condensed water is easy to form, causing the inner cavity of the statue and the welding parts to be rusted particularly seriously by the electrochemical corrosion and chemical corrosion. Compared with single chemical corrosion, electrochemical reaction can greatly accelerate the corrosion of iron. This result provided important scientific basis onto the production crafts of the precious casting, and the correlation between environment and deterioration for large outdoor iron relics, contributing to the conservators to make informed decisions on restoration.