This study presents evidence of two tuyères, or blowpipe tips, used in metalworking at the Postclassic period city of Mayapán. Blowpipe technology has long been hypothesized to be the production technique for introducing oxygen to furnaces during the metal casting process on the basis of ethnohistorical depictions of the process in ancient Mesoamerica. To our knowledge, the tuyères recovered at Mayapán are the first archaeologically documented tuyères for pre-Hispanic Mesoamerica. The dimensions, internal perforation, vitrification, and presence of copper prills within the ceramic fabric, suggest that they were used in pyrotechnological production, likely metalworking, and is consistent with previous evidence for small-scale metalworking at Mayapán. Blowpipe use in metallurgical production is a logical extension of a much longer tradition of blowgun use in hunting, which was likely already present in Mesoamerica by the time metal was introduced to West Mexico from South America. Furthermore, the dimensions of the Mayapán tuyères are consistent with the internal diameter of ethnohistorically-documented blowguns from Jacaltenango in the southwest Maya region. We conducted replication experiments that suggest that when combined with wooden blowpipes, the Mayapán tuyères would have been ideal for small-scale, furnace-based metallurgy, of the type identified at Mayapán from Postclassic period contexts.

Bamboo has been widely utilized as a load bearing material in building construction since ancient times by taking advantage of its excellent mechanical performances under loading as well as its low density and rapid growth. Applications of bamboo to engineering, architecture, and infrastructure require an in-depth understanding of the relationship between its morphology and mechanics, including how this regularly spaced segmental structure adapts to taking the applied loads. However, previous research on buckling behavior of structural bamboo considered it as a homogenous tube without multiscale structural features, and no reasonable explanation for the regular segment length was proposed. Here, we have implemented representative volume elements within the framework of finite element analysis to study the mechanical response of a bamboo culm under axial compressive load and systematically investigated how the bamboo's hierarchical structural features (e.g., gradient fiber distribution, periodic nodes, and others) contribute to its compression capacity. We find that column buckling is a critical failure mode that leads to the collapse of the entire structure, which can be disastrous. We observe that the gradient fiber distribution pattern along the radial direction significantly contributes to its strength. We find that the occurrence of fiber deviation at the node region reduces the strength of bamboo. Nevertheless, our results show that structural features such as external ridge and internal diaphragm play the role of reinforcement while the effect is more significant for bamboo than other plants with similar node appearance. Our work provides structural insights into the outstanding mechanics of bamboo. Such information could provide a guide for engineers to predict the material mechanics according to its structure, design bamboo-inspired composite materials, and construct high-performance architectures with bamboo accordingly.

The fibrillar organization is crucial for the mechanics of osteonal bone and for its anisotropy. Different collagen fiber orientation (CFO) patterns are observed in bone and correlated to the main local loading, leading to the hypothesis that the fibers are preferentially aligned to bear specific loading types. A heterogeneous distribution of osteon morphotypes (OMs) is noticed in long bones, although the relationship between the OM spatial distribution and the local predominant loading is still unclear. This study aims to shed light on the reasons why Nature uses specific OMs in diverse stress‐dominated regions. A multimodal approach is adopted, including collagen fiber orientation mapping, numerical modeling of different OMs under tensile and compressive loading, and 3D‐printing of OM‐inspired samples, to unravel the relationship between different OMs and their mechanical behavior. Simulation results suggest a better performance of the vertical OM (VOM) under tensile loading and of the twisted OM (TOM) under compression, confirming earlier hypotheses. The outcomes of mechanical testing, conducted on 3D‐printed samples, highlight a possible buckling‐induced failure of fibers with preferential vertical orientation and provide evidence that OMs are stress‐tailored, opening new venues for the design of stress‐tuned bioinspired composites.

Increasing redox reaction rates on carbon electrodes is an important step to reducing the cost of all-vanadium redox flow batteries (VRFBs). Biomass-derived activated carbons (ACs) hold promise as ...

Analysis of the Temple Scroll reveals another technology used to produce the Dead Sea Scrolls and potential preservation concerns. The miraculously preserved 2000-year-old Dead Sea Scrolls, ancient texts of invaluable historical significance, were discovered in the mid-20th century in the caves of the Judean desert. The texts were mainly written on parchment and exhibit vast diversity in their states of preservation. One particular scroll, the 8-m-long Temple Scroll is especially notable because of its exceptional thinness and bright ivory color. The parchment has a layered structure, consisting of a collagenous base material and an atypical inorganic overlayer. We analyzed the chemistry of the inorganic layer using x-ray and Raman spectroscopies and discovered a variety of evaporitic sulfate salts. This points toward a unique ancient production technology in which the parchment was modified through the addition of the inorganic layer as a writing surface. Furthermore, understanding the properties of these minerals is particularly critical for the development of suitable conservation methods for the preservation of these invaluable historical documents.

This work follows the recent discovery of a zinc-bearing Egyptian blue (EB) pigment widely used for the production of the early medieval mural paintings cycle in Santa Maria foris portas Church at Castelseprio (Lombardy Region, Italy). The inclusion of zinc in the synthesis of EB has been studied for the first time trying to evaluate whether its addition could be casual or deliberate. Historical reconstructions of the pigment have been carried out with a special focus on the use of zinc besides copper, using the different production methods. The influence of zinc on the pigment’s NIR photoluminescence and VIS-NIR reflectance has been characterized using FORS spectroscopy, X-ray diffraction, optical microscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy. A comparison of the production methods including salt-flux, solid-state, and Zn-rich syntheses showed that the solid-state synthesis results in particularly efficient NIR photoluminescence and VIS-NIR reflectance. Modern replicas were compared with an ancient sample in order to understand the zinc environment inside the structure of the Zn-enriched EB. Zn was found to be concentrated in a glass-based matrix surrounding cuprorivaite crystals, the main mineral associated with the EB pigment, and not included in a hypothetical Zn-doped cuprorivaite with formula CaCu1−xZnxSi4O10. The Zn-rich synthesis opens up the possibility of producing EB from brass and demonstrates that EB used in Castelseprio’s mural paintings could have been produced in this way. The relationship between the microstructure and the NIR photoluminescence of cuprorivaite-like pigments is of interest also for applications in modern and future technologies.

Aberrant lipid accumulation and marked changes in cellular lipid profiles are related to breast cancer metabolism and disease progression. In vitro, these phenomena are primarily studied using cells cultured in monolayers (2D). Here, we employ multicellular spheroids, generated using the MCF10A cell line series of increasing malignancy potential, to better recapitulate the 3D microenvironmental conditions that cells experience in vivo. Breast cancer cell lipid compositions were assessed in 2D and 3D culture models as a function of malignancy using liquid chromatography coupled with mass spectrometry. Further, the spatial distribution of lipids was examined using Raman chemical imaging and lipid staining. We show that with changes in the cellular microenvironment when moving from 2D to 3D cell cultures, total lipid amounts decrease significantly, while the ratio of acylglycerols to membrane lipids increases. This ratio increase could be associated with the formation of large lipid droplets (>10 μm) that are spatially evident throughout the spheroids but absent in 2D cultures. Additionally, we found a significant difference in lipid profiles between the more and less malignant spheroids, including changes that support de novo sphingolipid production and a reduction in ether-linked lipid fractions in the invasive spheroids. These differences in lipid profiles as a function of cell malignancy and microenvironment highlight the importance of coupled spatial and lipidomic studies to better understand the connections between lipid metabolism and cancer.

There has been significant progress in recent years aimed at the development of new analytical techniques for investigating structure-function relationships in hierarchically ordered materials. Inspired by these technological advances and the potential for applying these approaches to the study of construction materials from antiquity, we present a new set of high throughput characterization tools for investigating ancient Roman concrete, which like many ancient construction materials, exhibits compositional heterogeneity and structural complexity across multiple length scales. The detailed characterization of ancient Roman concrete at each of these scales is important for understanding its mechanics, resilience, degradation pathways, and for making informed decisions regarding its preservation. In this multi-scale characterization investigation of ancient Roman concrete samples collected from the ancient city of Privernum (Priverno, Italy), cm-scale maps with micron-scale features were collected using multi-detector energy dispersive spectroscopy (EDS) and confocal Raman microscopy on both polished cross-sections and topographically complex fracture surfaces to extract both bulk and surface information. Raman spectroscopy was used for chemical profiling and phase characterization, and data collected using EDS was used to construct ternary diagrams to supplement our understanding of the different phases. We also present a methodology for correlating data collected using different techniques on the same sample at different orientations, which shows remarkable potential in using complementary characterization approaches in the study of heterogeneous materials with complex surface topographies.

Nanocrystalline domains can be used to create robust anti-fatigue-fracture hydrogels for artificial cartilages and soft robots. The emerging applications of hydrogels in devices and machines require hydrogels to maintain robustness under cyclic mechanical loads. Whereas hydrogels have been made tough to resist fracture under a single cycle of mechanical load, these toughened gels still suffer from fatigue fracture under multiple cycles of loads. The reported fatigue threshold for synthetic hydrogels is on the order of 1 to 100 J/m2. We propose that designing anti-fatigue-fracture hydrogels requires making the fatigue crack encounter and fracture objects with energies per unit area much higher than that for fracturing a single layer of polymer chains. We demonstrate that the controlled introduction of crystallinity in hydrogels can substantially enhance their anti-fatigue-fracture properties. The fatigue threshold of polyvinyl alcohol (PVA) with a crystallinity of 18.9 weight % in the swollen state can exceed 1000 J/m2.

In recent years, great strides have been taken in the characterization of complex, heterogeneous ancient materials to gain a better understanding of their structure-function relationships. In this work, we apply a new set of high throughput characterization tools to study ancient Roman concrete, which is a particularly interesting material that shows heterogeneities and complexity across multiple scales, each of which are important for understanding its mechanics, its resilience, how it degrades, and for making informed decisions regarding its preservation.

AbstractPromoting the use of naturally available materials as a partial substitute to portland cement can be a viable solution for producing low carbon footprint and durable cements. This work asse...