Xiao Ma

The murals from Tomb No. 1 at Wulanquangou, Qinghai, China (633–842 CE), provide insights into mural materials and painting techniques during the Tibetan Empire. In this study, OM, SEM–EDS, XRD, μ-RS, FTIR, Py–GC/MS, ELISA, and LPSA were employed to characterize the mural materials and painting techniques. The murals comprise a multilayer structure consisting of brick and squared timber (Cupressus spp.) supports, an earthen ground layer, a lime ground layer, and a pigment layer. The lime ground is dominated by calcite, whereas the earthen ground consists mainly of fine-grained silty soil reinforced with highland barley fibers. Hematite, carbon black, and indigo were identified in the pigment layer, while animal glue was identified as the binding medium. The identification of indigo provides the first evidence of its use in a Tubo-period mural on the Qinghai–Tibet Plateau. Similarities in mural structure and painting techniques between Wulanquangou Tomb No. 1 and high-status Tang tomb murals in Shaanxi and Gansu suggest possible technological exchanges between the Tibetan Empire and Tang China.

The Sanxingdui Site's waterlogged ivory tusks, a testament to ancient sacrificial practices and a biogenetic archive of the Chengdu Basin's paleo-environment, face collapse due to centuries of burial-induced degradation. Clay and moisture clogging microcracks weaken their structure, greatly increasing the challenge of effective consolidation. Inspired by bone's natural resilience, we developed a biomimetic, minimally invasive method to preserve these cultural treasures, using Sanxingdui waterlogged and deteriorated ivories as a model. Through detailed analysis, we identified barriers to consolidation and introduced calcium-based solutions─calcium acetate solution for deep, clay-rich fissures and calcium hydroxide nanoparticle suspension for larger cracks, combined with diammonium phosphate─to form a bone-like hydroxyapatite network in situ within cracks and fissures. This strengthens artifacts by 69.7% in hardness and 90.9% in elastic modulus, reduces water loss during dehydration from 31.3 ± 2.6% to 9.6 ± 0.7%, and ensures stability after 180 days of aging (25 ± 3 °C, 85 ± 5% RH). Our integrated approach to material design, synthesis, and evaluation not only sets a standard for conserving waterlogged heritage materials, such as bones, wood, and textiles, but also inspires innovative binding solutions for fields like adhesives and civil engineering. Blending materials science with archeology, this work safeguards humanity's shared history.

Hydraulic calcium‐silicate‐hydrate (C‐S‐H), a key binding agent in both ancient mortars and modern cement, holds significant promise for heritage conservation. Drawing inspiration from ancient Roman techniques, this study investigates the development of C‐S‐H‐based grouting materials to address water‐induced erosive damage in the Beishan Grottoes of the Dazu Rock Carvings. The interfacial interactions between C‐S‐H mortar and sandstone are analyzed using molecular dynamics simulations, revealing the crucial role of hydrogen bonding at the interface of C‐S‐H and mineral phases for adhesion. In the in situ synthesis of C‐S‐H with a reticulated structure from Ca(OH) ₂ /silica fume mixtures under ambient conditions, this work systematically investigates the impact of varying calcium‐to‐silica (C/S) ratio and water‐to‐binder ratios on the mechanical properties and pore structure of C‐S‐H‐based mortars. The optimal mechanical and physical properties are achieved with a C/S ratio of 0.8, water/binder ratio of 2.0, binder/aggregate ratio of 1:3, and 4 wt% polycarboxylate superplasticizer. Laboratory‐scale experiments confirm its excellent compatibility with sandstone, offering a potential effective grouting solution for the Beishan Grottoes and emphasizing the importance of material compatibility in heritage conservation. This integrated approach encompassing materials design, synthesis, characterization, and interfacial analysis, presents a robust framework for developing tailored binding agents for various applications.

The freezing behaviors of water are one of the most critical factors that define the formats of life and the landscapes on Earth. The current methods for regulating the freezing behaviors mainly rely on ice-structuring proteins or nanomaterials to hinder the conversion of water into crystalline ice (Ih) under low temperatures. Here we report that minuscule mineral particles can significantly suppress the volume expansion upon water freezing into ice (Ih). In particular, colloidal precipitates of calcite, a primary mineral accounting for ~4 wt% of the Earth’s crust and the most abundant biomineral on Earth, are able to reduce water expansion by 69% (from 8.4% to 2.6%) at 243 K. The mechanism of expansion suppression involves the formation of a continuous network of fairly ordered “ice-like” hydration waters that are bound to the surface of the mineral colloids, and their concurrent crystallization through heterogenous nucleation upon freezing, which confines the interstitial free water. These findings reveal the remarkable ability of common minerals to suppress the volume expansion associated with the most ubiquitous phenomenon of water freezing and offer fresh insights into various fields such as biomineralization, hydrology, soil science, and lithology.

The Lin Yimu’s tomb in Zhejiang Province, China, is a significant Qing Dynasty tabia structure that, despite relatively good preservation, has suffered damage from weathering, necessitating urgent restoration. In this study, we conducted a comprehensive scientific analysis of archaeological samples from the tabia of Lin Yimu’s tomb, employing a range of analytical techniques including X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX), Fourier transform infrared spectroscopy (FTIR), chemical methods, and measurements of hardness and strength. Analytical results revealed that the main phases of the sample are calcite, quartz, illite/mica, feldspar, with a minor presence of Tung oil. The proportion of calcium carbonate is approximately 27%, and the ratio of earth to sand is 1:2, suggesting a raw material formula mass ratio of lime-earth-sand of 3:4:8. The surface hardness of the sample is measured at 293 ± 15 HL, with a compressive strength of 5.5 ± 0.2 MPa. The sand used in the raw material has a medium particle size of 250 μm, while earth particles are predominantly around 17 μm. The sample exhibits a porosity of 27.5%, with pore sizes concentrated at 95 nm. These findings contribute significantly to our understanding of Qing dynasty tomb construction technologies and provide a solid scientific basis for the restoration of such historical sites.