Abstract:The degree of polymerization of paper cellulose is one of the key factors affecting paper’s lifetime and mechanical properties. Research on the degree of polymerization of handmade paper is important for dating ancient paper and evaluating the quality of restoring paper. In our work, we used Yingchun, Zhuma, Yuanshu and Longxucao papers as the model substrates of mulberry bark, ramie, bamboo and Eulaliopsisbinata papers, respectively, to study the applicability of the copper ethylenediamine (CED) method for the detection of handmade paper, and to further investigate the effects of lignin content, dissolution time and the presence or absence of air on the intrinsic viscosity of paper. The results indicate that the CED method is suitable for the determination of handmade paper with a lignin content below 10%. The intrinsic viscosity and degree of polymerization of handmade paper can be calculated from the actual concentration of cellulose after subtracting the lignin content. In the dissolving process, paper should first be impregnated in water for 2 hours, which will shorten the dissolution time. In addition, air should be excluded during the test to prevent the degradation of cellulose and to improve the accuracy of testing results.

Abstract:There are many precious cultural relics of paintings and calligraphy in museums of China, but effective restoration of them is difficult due to their material characteristics. Paste between paintings or calligraphy and backing papers is the main obstacle in the process of taking off old backings. Amylase has been used to effectively decompose starch paste, which improves the efficiency of taking off old backings; however, residues of amylase on cultural relics could influence subsequent remounting. Therefore, development of a thermosensitive amylase could contribute to the process of remounting after taking off old backings. In our study, a bacterial strain named BWL1025 that can secrete thermosensitive amylase, was isolated from soil sampled in the cold northeast area. Using methods of molecular biology, the strain BWL1025 was identified as Bacillus subtilis. The optimum conditions for enzyme activity, the pH stability, the lowest inactivation temperature and the minimum inactivation time of the amylase produced from BWL1025 were determined by the DNS method. The results show that the enzyme activity reached its highest activity of 0.839 IU/mL at 40 ℃, but almost disappeared after 25 minutes at 60 ℃. In addition, we optimized the fermentation conditions of the strain BWL1025, and found that the highest activity of 1.63 IU/mL was observed when yeast extract was used as nitrogen source and xylose as carbon source. This study provides a good enzyme source for taking off old backings from cultural relics of paintings and calligraphy.

Abstract:With the goal of finding better ways to protect and restore ancient silk objects, we applied a new type of silk restoration technology—transglutaminase (TGase)-mediated protein polymerization restoration, utilizing the principles of cultural relic protection, to reinforce and protect the fragile silk of M1:215 from Nanling County, Anhui Province. We also discuss the restoration mechanism. The effects of the reaction on silk fibers were evaluated using tensile tests, color difference tests, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectrometry, etc. The results show that the tensile strength, elongation rate at breakage and micro-morphology of the silk were remarkably improved without significant change in color after restoration. FTIR spectrometry confirmed the formation of transglutaminase-induced biopolymers in the restored silk samples and demonstrated that the transglutaminase-mediated restoration did not change the basic structure of silk protein. As a compatible and innocuous consolidation method, transglutaminase-mediated restoration has been applied, here, to genuine historical silk fabrics and achieved desired results. This work provides important technical support for the future protection and restoration.

Abstract:The 2015 Nepal earthquake caused immeasurable damage to the world cultural heritage sites in Kathmandu Valley. In order to explore the overall distribution and characteristics of this damage, a field investigation was carried out on the seismic damage to the world cultural heritage buildings in the valley, including establishment of three categories of damage. Seismic damage maps of six world cultural heritage sites were created and then analyzed statistically. In the three Durbar (royal palace) Squares of Kathmandu, Patan and Bhaktapur, 39.5%, 53.3% and 50.0%, respectively, of the cultural heritage buildings were basically well-preserved. The main bodies of Swayambhunath, the Great Boudha Stupa and Changu Narayan Temple were basically well-preserved, but the affiliated buildings were damaged to varying degrees. The soft sediments present in Kathmandu, Patan and Bhaktapur Durbar Squares amplified the earthquake effect, causing serious damage to buildings. The seismic damage in Swayambhunath and Changu Narayan Temple was mainly influenced by topographic features. These research results provide reference for seismic protection of similar heritage buildings in China.

Abstract:To effectively mitigate damage to cultural objects in museums, we have developed a rolling-type horizontal isolation device which can be used for showcases for cultural objects. In order to evaluate its performance, we made two showcase models in each of which a cultural relic imitation was placed in a freestanding way, and carried out shaking table tests on them for comparison. One showcase was placed freestanding directly on the bed of the shaker table, while the other was fixed at the bottom to the isolation device which was then placed freestanding on the shaker table. The results show that, compared with the non-isolation case, the isolation system has a smaller basic frequency and a larger damping ratio. Under the effects of horizontal earthquakes, utilization of the isolation device results in smaller displacement and acceleration responses, but its dynamic magnification coefficient still sometimes exceeds 1. Furthermore, the reset ability of the isolation device also needs improvement. It is suggested that measures need to be taken to further decrease the basic frequency, increase the damping ratio, and improve the machining precision, etc. of the isolation device.

Abstract:Stone relics suffering from diseases such as cracks due to deterioration, need proper restoration methods. In our work, in order to simulate the restoration of cracks in stone relics, the technology of microbially-induced carbonate precipitation was applied to the restoration of broken marble beams. The research objects were some white marble beam models (40 mm × 40 mm × 160 mm) with V-shaped cracks, some of which penetrated the beam completely and some that did not. The restoration method was grouting and free infiltration. The effect of restoration was evaluated by comparing the change of load capacity and flexural strength before and after the restoration and by visualizing the restoration process of through cracks using computed tomography (CT) scanning. The results show that after restoration, 1) the surfaces of the cracks are dense and smooth, the color is similar to that of the base material and that the overall appearance is nice; 2) the load capacities of beams with non-through cracks were all increased, and the flexural strengths of the beams with through cracks reached a mean value of 3.684 MPa (recovering up to 35.12% of the original strength) and the maximum value of 5.234 MPa. The qualitative and quantitative results of CT scanning also indicate that the density of bio-cementation increases as the restoration goes on, and that the restoration quality of contact surfaces is weaker than that of other locations.

Abstract:In order to evaluate the structural performance of stone arch bridges built in the Ming Dynasty and to suggest appropriate strengthening techniques, we studied Yongchang Bridge, an example of typical Ming stone arch bridges. First, the bridge was surveyed in detail to obtain its geometrical dimensions. Next, the architectural forms, configurations and damage were studied to provide bases for analysis. Then, the software of ANSYS was used to establish a finite element model of this bridge, to study the influence of loading, importance of structural elements and crack distribution. Finally, based on the analysis of actual status and structural performance, we proposed and compared two strengthening methods—the concrete strengthening method and the carbon fibre reinforced polymer (CFRP) strengthening method for the stone arch of this bridge in order to obtain an adaptive strengthening method for Yongchang Bridge. These results could be referred to in efforts to conserve similar ancient stone arch bridges.

Abstract:Four Tang Dynasty tombs with mural paintings have been excavated in southern suburbs of Xi’an. These tombs date from the early to the late Tang Dynasty. In order to identify the composition and discuss the history of application of yellow pigments used for these mural paintings, polarizing microscopy, Raman spectrometry, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) and X-ray diffraction (XRD) analysis were carried out. Results of the analysis show that yellow pigments used for the three mural paintings from the early to the middle Tang Dynasty are goethite, while that for a late Tang Dynasty mural painting is vanadinite, which is the first case of its use in the late Tang Dynasty ever found (before, uses of vanadinite were found only in mural paintings of a Western Han Dynasty tomb and the tomb of Han Xiu of the flourishing Tang period). The finding of vanadinite as a yellow pigment could be an important supplement to evidence for studying the history of application of vanadinite in mural paintings in Xi’an. In addition, according to a survey of relevant literature, the pigments in this paper were supposed to have been obtained from local sources.

Abstract:We analyzed the mechanism of degradation of waterlogged archaeological wood from Haimenkou Sites using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These observations show that the secondary walls of wood cells shrink very seriously and are separated from the intercellular layers, but that the latter remain relatively intact, presenting a continuous network. The results indicate that the degradation of cellulose and hemicellulose is serious while that of lignin is relatively mild. The archaeological wood suffers mainly from bacterial degradation which is demonstrated by significant bacterial decay characteristics as determined by SEM and TEM observation. Bacteria first invade the cell lumen, and then invade the cell wall through the S3 layer. The cell wall lacuna due to degradation varies between tens to hundreds of nanometers. The archaeological wood is also degraded by fungi to a certain degree. With weaker ability to degrade cell wall materials, such fungi mainly degrade starch and other substances, making archaeological wood darker.

Abstract:Analytical research on the gold and silver decoration technology for several pieces of fabric core lacquerware excavated from Haiqu Han Dynasty Tomb Site in Rizhao, Shandong Province, was carried out using microscopy and other methods. Gold ornaments are mostly inlaid in lacquer film layers, while silver ornaments and other silver components are mostly inlaid in the lacquer ash layer. For protection purposes, there are decorations coordinated with the surrounding patterns at the junction between gold or silver ornaments and the lacquer film. The decorations on gold and silver are in harmony with the decorative patterns around them. Preliminary inquiry about the gold and silver decoration technological process for fabric core lacquerware has been made in combination with the investigation results of modern lacquerware decoration technology. The research is helpful to the discovery, utilization and inheritance of the gold and silver decoration technology for Han Dynasty fabric core lacquerware.

Abstract:In order to study the architectural form and structural performance of the special type of Chinese architectural heritage—brick-vault halls built in the Ming Dynasty, the brick-vault hall of Yongzuo Temple was taken as an example. First, the accurate geometric dimensions of this building were obtained by a survey using a three dimensional scanner. Then, the architectural form of this building was studied based on the analysis of some relevant historical literature. In addition, the material strength of the hall was achieved using a nondestructive testing method. A finite element model of this building was created to analyze its structural performance based on knowledge of the accurate geometric dimensions and the accurate material strengths. These results could contribute to the conservation strategies for other buildings of this type.

Abstract:The underground storerooms of the Palace Museum were built in 1986. After many years, earthquake prevention has become an outstanding issue of the storerooms. Based on the difficulties that would be encountered in reconstruction of the underground storerooms, a more suitable solution to the seismic problem has been proposed. The plan is to utilize a seismic isolation device composed mainly of chucks, guide-bars and damping plates, that is simple in structure and easy to install. In order to evaluate its effectiveness, we created a finite element analysis model and selected three seismic waves for time-history analysis. The results show that 1) the independent, unprotected storage cabinets in these storerooms have poor seismic performance, in that they sway violently and even overturn under the condition of a 9-degree rarely-occurring earthquake; 2) when using the anti-seismic device, the sway amplitude of the combined double cabinets decreases significantly as a result of increasing the sliding distance to dissipate the seismic energy, giving the maximum amplitude of only 1.64° (El Centro wave). Therefore, the analysis results demonstrate the seismic effectiveness of the device.

Abstract:Yue Ming Cang Hai”, a Yuan Guqin (a seven-stringed plucked instrument) made in 1352, is among the collections of Shanghai Museum. Damages, such as worm holes, decay and color fading, have been found on the instrument. A restoration plan was made accordingly, followed by a series of handlings including cleaning, reinforcing, matching, painting, polishing and distressing, etc. The results show that the combination of traditional techniques and modern analytical technologies made the restoration of this instrument a success.

Abstract:The effects of harmful pollutants in domestic drinking water and their harm to paper fibers, based on the analysis of domestic and foreign literature and related investigations, are summarized. In discussions of the use of water for paper restoration, it is pointed out that purified water (obtained via reverse osmosis and deionization, etc., of sufficiently high resistivity) should be selected for this purpose. It is better to use ultrapure water with higher resistivity where possible. In order to ensure that purified water is not re-contaminated after purification, it should be used right after being made. In terms of equipment, selection of a small pure water system can ensure better water quality.

Abstract:The extraction and study of cultural relic information plays an important role in revealing historical information about ancient relics in terms of human society and culture. On the one hand, it helps us understand the features of ancient technologies and explore the origin and development history of craftsmanship of artifacts. On the other hand, the investigation and analysis of damage provides valuable information for subsequent conservation. In this paper, infrared spectroscopy is introduced as a tool to guide the conservation of cultural relics. The cultural relics involved include inorganic ones (eg., bronze wares, soil, pigments, jewelry and jade) and organic ones (eg., paper, silk, painting glue and organic residues and protection materials). It is proposed that this technology has a wide range of applicability and strong characteristics, is non-destructive or requires only tiny samples, and is not restricted by the state of samples. However, it still has the limitation of not being suitable for analyzing water-bearing samples, having large errors in quantitative analysis and relying on experience to analyze spectra. Infrared spectroscopy offers the prospect of broad applicability in the field of nondestructive analysis of cultural relics, and also provides reference for the research of cultural relic conservation.