The layered semimetal WTe 2 undergoes reversible halogen intercalation to give modulated WTe2I and multistage WTe 2 Br x with room-temperature “breathing” behavior.

Adhesives are among the most informative archaeological artefacts for understanding the behaviour of Stone Age forages. In the southern African Middle and Later Stone Age, the botanical origin of most adhesives was identified as conifers of the genus Podocarpus. One of these identifications of Podocarpus adhesives comes from Elands Bay Cave. However, it has recently been shown that similar adhesives can be, and were, produced from many plants available on the southern African subcontinent, opening important questions about the role of Podocarpus within these plants. Here, we re-investigate the Elands Bay Cave adhesive record and compare it to natural and experimentally produced adhesive substances, using infrared spectroscopy and mass spectrometry. We find that Elands Bay Cave artefacts were made from the leaves of several plant species including Podocarpus spp using the condensation method. We also identify the oldest archaeological record for an adhesive based on water-soluble plant gum. These findings have important implications for our understanding of Stone Age adhesives as proxies for human evolution and the dynamics of invention.

We identify the oldest known example of systematic heat treatment of chert in the world. The specimens come from the base of one of Australia’s oldest archaeological sequences, Nauwalabila I, in Arnhem Land, which is dated to at least 45–40 ka and probably older than 55 ka. The presence of this heat-based transformative technology in Australia has significance for reconstructions of technological evolution. One possibility is that chert heat treatment in Australia was an independent innovation. The early Australian practice of chert heat treatment is almost twice as old as is known anywhere in Eurasia, and if this developed independently in multiple places, the Australian antiquity need not be an indication of the antiquity of innovations in other regions. The difficulty with this interpretation is that chert is technically challenging to transform, creating a large innovation gap if more simple heat treatment technologies are not already in place. An alternative model is that groups of H. sapiens dispersing from Africa/West Asia possessed knowledge of stone heat treatment. Heat treatment may have spread to Australia, through South Asia and Southeast Asia, as dispersing groups continued existing practices of chert heat treatment, revealing maintenance and transmission of complex technological knowledge throughout the initial eastward spread of humans. If heat-treating knowledge persisted in the long-term, it is likely that chert treatment evolved through transference/modification of knowledge from different rock materials, such as silcrete, a material with wider thermal tolerances and more suited to the spontaneous discovery of heat treatment knowledge. This is the case in Africa, where silcrete heat treatment long predates chert treatment. However, in Australia, no silcrete treatment is evident prior to this early chert heat treatment. Silcrete at Madjedbebe, a contemporaneous site near Nauwalabila, was not heat-treated. If the transfer of heat treatment practices from silcrete (or similar rocks) to chert was a typical step in the evolution of this kind of technology, the early Australian assemblages we report here set a minimum age for this reconfiguration of thermal technology.

This study investigates the mechanical characteristics of lithic raw materials used during the Paleolithic in the Japanese Archipelago, focusing on Wada-toge obsidian, Happusan andesite, and shale from the Akaya Formation. Although these sources have been well documented, few studies have examined their mechanical behavior. To evaluate the knapping quality (or fracture predictability), we measured several mechanical indicators on geological samples. Comparisons with Paleolithic assemblages suggest that the distinct mechanical signatures may have constrained prehistoric knapping strategies and influenced lithic artifact morphology. These findings highlight the mechanical property measurement for understanding prehistoric resource procurement and technological behavior in the Japanese Archipelago.

Halogen intercalation into the layered material tungsten ditelluride (WTe2) provides a unique pathway to tune its structural and electronic properties. In this study, we detail the synthesis and characterization of the new bromine-intercalated phases WTe2Brx (x = 0.5, 1.0, and 1.25), and reinvestigate the iodine-intercalated analogue, WTe2I. A defining feature of the bromine system is its rapid and re-versible "breathing" behavior at room temperature, allowing guest molecules to be absorbed or released from the van der Waals gaps under ambient conditions. Structural analysis shows that the bromine-poor phase WTe2Br0.5 crystallizes in the orthorhombic space group Pmmn, thereby maintaining a uniform stacking sequence. In contrast, the bromine-rich WTe2Br1.25 phase (space group Imm2) adopts an architecture where two distinct types of bromine layers alternate between the host layers. For the iodine system, the compound WTe2I exhibits both incommensurate and commensurate (3 + 1)D modulated variants in the superspace group P21/m(α0γ)00. In the commensurate polytype, the structural modulation locks into a rational vector, q = (1/2, 0, 1/6), which can be described also as a 3D supercell. Electronic structure calculations show WTe2Br0.5 and commensurately modulated WTe2I to be metals with flat bands at the Fermi energy arising from the intercalation. These findings demonstrate the unusual stability and structural flexibility of anionic intercalation in transition metal dichalcogenides.

The raw materials people used for making stone tools may contain information about their territory, exchange routs or the selection criteria they employed during provisioning. In this study, we measure the mechanical properties of different tool-stones used by foragers living during the Middle Stone Age at Sibhudu Cave in South Africa. The site yielded a long and continuous sequence that saw transitions between different raw materials and tool forms. We evaluate the quality of these different stones for tool making and use, attempting to find correlations between selected raw materials and the tools made from them. We find that the raw materials used at Sibhudu have substantially different qualities, some being easy to flake but weak upon use, some being tough during stone knapping and resistant during use. Comparing these data with the appearance and disappearance of tool types throughout the Sibhudu sequence, we note that tool-stones requiring lower flaking forces were more often retouched than those requiring great forces. Elongated products, blades, were mostly made from materials with better fracture predictability, suggesting an understanding of the basic requirements for standardising the tool knapping process. Use-related qualities, such as resistance to dulling, appear to have been of lesser importance at Sibhudu. Our results suggest that the site's occupants had a good understanding of the qualities of rocks for specific knapping processes.

The manufacture of limestone beads using so-called Dickenbännli drills has been proposed to be part of a large-scale societal development: specialization of labor and the resulting emergence of social stratification. These small lithic drills are abundant at many Middle and Late Neolithic sites in Southern Germany and Northern Switzerland, frequently co-occurring with limestone beads. However, the use of the drills for bead manufacture is mostly assumed rather than demonstrated. Furthermore, there is little experimental, technological and traceological evidence to support the hypothesis of a specialized production, except for the site of Hornstaad-Hörnle, where the argument is based on spatial distribution and manufacturing skill. The Late Neolithic assemblage of Kohlhau-Abri, which includes both drills and disc bead fragments, serves as a case study to reconstruct the manufacturing process of drills and limestone beads and evaluate their interconnection, ultimately examining the technical skills involved. This was achieved through explorative and controlled experiments, coupled with traceological and residue analysis of both drills and beads. Our use wear results show that the drills were used, likely to work limestone. Raman spectroscopy of a white residue found at the tip of one of the drills indicates calcite, the primary component of limestone. Neither the experimental nor the archaeological evidence suggests a necessity for specialists in bead manufacturing. Our study highlights how the application of multiple analytical approaches can provide us with complementary lines of evidence, and how such a holistic approach enables us to tackle not only small-scale but also large-scale questions.

We explore the cationic intercalation of tungsten ditelluride (WTe2) with potassium (K), rubidium (Rb), and cesium (Cs), yielding intercalation compounds of the form A0.5WTe2 (A = K, Rb, Cs). Structural characterization was performed using powder X-ray diffraction (PXRD), while diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and temperature-dependent conductivity measurements were employed to investigate the electronic properties. Density functional theory (DFT) calculations were carried out to support the experimental findings and to provide insight into the intercalation mechanisms and the resulting material characteristics. All synthesized compounds display semiconducting behavior with narrow band gaps, emphasizing the influence of alkali metal intercalation on the electronic structure and transport properties of WTe2. These results advance the fundamental understanding of property modulation in transition-metal dichalcogenides (TMDCs) and highlight their potential for electronic device applications.

The study of raw materials used for making stone tools allows archaeologists to gain insight into the behaviours of ancient people. Raw materials possess different properties, which influence the ability of knappers to flake, shape and use a stone tool. Measuring these properties experimentally requires specialised laboratories and measuring processes that are not straightforward. This makes such analyses a cost-intensive and often inaccessible way to investigate the past. Here, we present an alternative way to evaluate two mechanical properties, stiffness and hardness, using a single indentation test. We also test whether these two isolated measures allow making predictions on raw material selection and tool shape. We analysed tool-stones from the Middle Stone Age site Sibhudu on South Africa’s eastern seaboard. The site has yielded a rich assemblage of tools from different raw materials. We found that a single indentation test allows measuring hardness and stiffness reliably, simplifying the measurement protocol of raw material studies. We also observed weak correlations between those isolated properties and the shape of the finished tools. This has implications for future studies of Stone Age raw materials, proposing a simplified testing protocol. We also discuss the role of stiffness in stone knapping.

The pursuit of efficient nonlinear optical materials is critical for advancing optoelectronic applications. This study focuses on the synthesis and characterization of HgCl2(C3N6H6), a melamine-based hybrid metal halide. Structural analysis reveals a non-centrosymmetric lattice facilitated by large asymmetric secondary building units and a pi-conjugated system. The compound exhibits a strong second-harmonic generation efficiency. Density functional theory calculations, optical band gap measurements, and photoluminescence measurements specify the electronic properties. For completeness and analytical comparison, the centrosymmetric compound Hg2Cl2(C3N6H6)2 is also introduced.

Archaeologists can use the provenance of lithic raw materials to examine the movements, territories, and settlement dynamics of hunter-gatherers. Several studies have used macroscopic analyses to propose the long-distance transport of raw material during the Gravettian and the Magdalenian of the Swabian Jura in Central Europe. Until now hypotheses about raw material transport in this region were not based on reproducible analyses. This study aims to test some of the hypotheses about the origins of lithic raw materials during the Gravettian and Magdalenian, using infrared spectroscopic measurements. These analyses are based on differences and similarities in the mineralogy and crystallography of rocks. Using this method, we test for long-distance raw-material transport between the sites of the Swabian Jura and the Freiburg basin, 200 km to the south-west, and the region of the Altmühl Valley, 150 km to the north-east. For this, we created a reference database of 114 lithic raw material outcrops from Southern Germany and compared these specimens with artifacts from eleven archeological sites. Our study reconstructs the raw-material procurement and transport during the Gravettian and Magdalenian and reveals settlement patterns and territories that span over more than 300 km in Central Germany.

The zinc halide-melamine system was investigated by conducting exploratory solid-state reactions and hydrothermal syntheses, yielding Zn3(OH)2Cl4(C3N6H6)3 and (C3N6H7)ZnX3(C3N6H6) with X = Cl and Br. All compounds were characterized by single-crystal X-ray diffraction, revealing that there are two modifications of the melaminium-zinc-chloride-melamine compound, crystallizing with non-centrosymmetric space groups (Pna21 and P21). The presence of delocalized π-electron systems in compounds containing cyclic (B3O6)3-, (C3N3O3)3-, or melamine derivatives is known to give rise to significant second harmonic generation (SHG) properties, provided that the given structure has no inversion center. All crystal structures feature Zn2+ in a tetrahedral coordination environment, forming layered structures. Spectroscopic measurements on phase-pure orthorhombic (C3N6H7)ZnBr3(C3N6H6) resulted in direct and indirect band gaps of 4.74 eV and 4.46 eV respectively. Measurements of the nonlinear optical response performed on single crystals of three different compounds revealed significant intensities following the sequence monoclinic (C3N6H7)ZnCl3(C3N6H6) > orthorhombic (C3N6H7)ZnBr3(C3N6H6) > orthorhombic (C3N6H7)ZnCl3(C3N6H6). Their SHG properties are compared with those of KTP, one of the most widely used SHG materials.

In March 2022, an auction house in Zurich sold two female figurines made from mammoth ivory, along with other prehistoric artefacts. This is a rare occurrence because the scarcity and value of Paleolithic figurines have limited their presence in the international art market. Researchers from the Archaeological Museum Hamburg and the University of Tübingen subsequently undertook in situ and non-destructive investigations to illuminate the authenticity of the two figurines. We conducted a comprehensive analytical study that included detailed microscopic optical observations and spectroscopic investigations. This methodological approach, combined with a thorough comparison to contemporary ivory figurine replicas, proved effective and clearly demonstrated that the specimens were forgeries. Research efforts of this kind are crucial, as they significantly help reduce the spread of intentional fakes posing as genuine artefacts in the art market. By doing so, we foster collaboration between academic institutions and the art market to preserve and protect the integrity and value of authentic archaeological and cultural heritage.

Two niobium oxyiodide compounds are presented, based on the novel [Nb 7 O 5 ] cluster core. Theoretical calculations suggest some oxygen orbitals mixing with niobium orbitals near the Fermi energy, as well as a three-centred bond between niobium atoms.

Stone tool knapping quality is an important parameter in the study of lithic technology. A number of experimental and objective studies have contributed to the discussion on how stone quality affects the knappability and the final shape of an end product. However, systematic studies on how stone mechanical properties affect knappability and raw material selection behaviour remain few. Here, we investigate geological and archaeological samples of porphyry, chert, and sandstone from the Palaeolithic sites of southern Kazakhstan to evaluate whether the acquisition of raw materials was driven by specific mechanical properties (e.g., ease of knapping). We tested their degree of knappability using the Vickers indentation method and four-point bending tests. Our results suggest high variability in the mechanical properties of the studied samples. Porphyry and chert demonstrate unexpectedly high values of force to initiate a knapping crack and low fracture predictability. Despite such knapping force requirements, these raw materials were preferred by their knappers, suggesting that raw material selection was governed by other criteria, such as resistance to abrasion and edge damage.

The zinc halide–melamine system was investigated by conducting exploratory solid-state reactions and hydrothermal syntheses, yielding Zn 3 (OH) 2 Cl 4 (C 3 N 6 H 6 ) 3 and (C 3 N 6 H 7 )ZnX 3 (C 3 N 6 H 6 ) with X = Cl and Br.