Core Reduction Research Articles

An atlas of the aging mouse proteome reveals the features of age-related post-transcriptional dysregulation

To what extent and how post-transcriptional dysregulation affects aging proteome remains unclear. Here, we provide proteomic data of whole-tissue lysates (WTL) and low-solubility protein-enriched fractions (LSF) of major tissues collected from mice of 6, 15, 24, and 30 months of age. Low-solubility proteins are preferentially affected by age and the analysis of LSF doubles the number of proteins identified to be differentially expressed with age. Simultaneous analysis of proteome and transcriptome using the same tissue homogenates reveals the features of age-related post-transcriptional dysregulation. Post-transcriptional dysregulation becomes evident especially after 24 months of age and age-related post-transcriptional dysregulation leads to accumulation of core matrisome proteins and reduction of mitochondrial membrane proteins in multiple tissues. Based on our in-depth proteomic data and sample-matched transcriptome data of adult, middle-aged, old, and geriatric mice, we construct the Mouse aging proteomic atlas (https://aging-proteomics.info/), which provides a thorough and integrative view of age-related gene expression changes.

Middle Stone Age technological organisation from MIS 5 at Mertenhof Rockshelter, South Africa

Lithic technological organisation within the southern Africa Early Middle Stone Age (∼315,000–80,000 years ago) has seen relatively little investigation owing to the subtly of technological change, frequent use of locally derived raw materials, and the archaeological spatio-temporal discontinuity. This has resulted in relatively limited use of explanatory models for technological variability, including mobility, provisioning, tool production, and core reduction strategies. This paper uses 2952 artefacts to test the lithic technological organisation across Marine Isotope Stage 5 units of Mertenhof Rockshelter. Here we argue that the scales and concepts currently used to approach Early Middle Stone Age technology requires reconsideration. The Mertenhof sequence exhibits high proportions of non-local raw materials with their transport reflective of tactical adjustments within relatively stable mobility, provisioning, and reduction strategies. We demonstrate that Early Middle Stone Age populations maintained a diverse array of tactical solutions across these strategic domains, offering a durable and flexible strategy that would be adapted to changing contexts.

An Actualistic Experimental Study of Giant Quartzite Core Reduction Strategies: Implications for Large Flake Blank Production and Handaxe Manufacture at Amanzi Springs, South Africa

ABSTRACT The later Acheulian assemblages (ca. 534–< 390 ka) from Amanzi Springs in South Africa show a preferential selection for large flake blanks when undertaking large cutting tool manufacture. However, due to the small number of giant cores from the site, we have limited insight into the technical preparation of quartzite raw material packages for large flake production. Here, we present an actualistic experimental study to better understand these procedures at the site and to gain perspective on how knappers may have reduced quartzite boulders of differing internal qualities. Our results highlight the influence of raw material constraints and how the overall morphology of quartzite boulders in turn impacts giant core reduction sequences and large flake blank morphologies. Finally, the experimental study exemplifies the need for high levels of knapping expertise to deal with tough, heterogeneous quartzite varieties.

Beyond Large-Shaped Tools: Technological Innovations and Continuities at the Late Early Pleistocene Assemblage of El Barranc de la Boella (Tarragona, Spain)

The emergence of the mode 2 technocomplex, traditionally characterized by the development of large cutting tools (LCTs) or standardized large-shaped tools, has also implied a range of new technological behaviours. These include enhanced raw material management, more sophisticated knapping strategies, and transport patterns, among other innovations. Unit II of the localities of La Mina, El Forn, and Pit 1 in El Barranc de la Boella (Tarragona, Spain) — dating back to between 0.99–0.78 million years ago — contains the oldest mode 2 assemblages in the European subcontinent and represents an exceptional opportunity to examine the technological features associated with the appearance of LCTs in Europe and to provide clues to shed light to different hypotheses about their appearance. The presence of functionally diverse but environmentally similar localities enables a study of behavioural flexibility and technological variation, marking a critical contribution to understanding early human technological evolution. Our research focuses on the technological behaviours of hominins in unit II of Pit 1, La Mina, and El Forn at Barranc de la Boella, examining five keys technological aspects such as (1) raw material management, (2) core reduction sequences, (3) reduction intensity, (4) large flake production, and (5) the spatiotemporal integrity of reduction sequences. We compare these behaviours with those observed in mode 1 (~ 1.8–0.9 Ma) and early Middle Pleistocene (~ 0.78–0.6 Ma) assemblages across western Europe. Our findings reveal significant advancements and anticipatory behaviours at El Barranc de la Boella, such as the use of procedural templates for core reduction strategies and the production of large-shaped tools governed by principles of gestural economy, and also the existence of different reduction sequences in different raw materials according to specific purposes. The technological behaviours observed at El Barranc de la Boella seem to be more indicative of population dispersals rather than local evolutionary developments from mode 1 technologies. The non-linear evolution of core knapping strategies, along with the variability in large-shaped tool types, suggests multiple waves of hominin dispersals into Europe during this crucial period. We propose that El Barranc de la Boella may represent an early dispersal of the Acheulean from Africa around 1.4 million years ago, potentially connected to assemblages such as ‘Ubeidiya. This study underscores the complexity of lithic technology during this period and contributes significantly to our understanding of the complex emergence and adoption of new technological behaviours in European early mode 2 assemblages, extending beyond the mere appearance of LCTs.

Investigations on the Effects of Bonding and Forming Conditions on the Deformation Behavior of Copper-Steel Bimetallic Rods during the Cold Drawing Processes.

Metal composite parts are widely used in different industries owing to their significant improvement in material properties, such as mechanical strength, electrical conductivity, and corrosion resistivity, compared to traditional single metals. Such composite parts can be manufactured and processed in different ways to achieve the desired geometry and quality. Among various metal forming techniques, drawing is the most commonly used process to produce long composite wires or rods from raw single materials. During the drawing process of composite wires or rods, not only does the core radius ratio change, but the core or sleeve layer may also undergo necking or fracture due to excessive tensile stresses in the softer layer. In this paper, bimetallic rods with AISI-1006 low-carbon steel cores and C10100 oxygen-free electronic copper sleeves are modeled using the finite element software DEFORM. The simulation models are verified by drawing experiments. The effects of initial bonding conditions, the initial core ratio, reduction ratio, semi-die angle, drawing speed, and friction on the plastic deformation behavior of the bimetallic rods are investigated. The results indicate that the initial bonding conditions have a great impact on the deformation behavior of the billets in terms of strain distribution, material flow, residual stress, and the final core ratio. The permissible forming parameters for obtaining a sound product are investigated as well. With the aid of these analyses, the drawing process and the quality of the products can be controlled steadily.

The use of carinated items in the Levantine Aurignacian-Insights from layer D, Hayonim Cave, W. Galilee, Israel.

A longstanding debate concerns the function of carinated elements in both, the Levantine, and European Aurignacian. The present study aims to contribute to this topic with the evaluation of the carinated assemblage from layer D in Hayonim Cave, Western Galilee, Israel, one of the type sites of the Levantine Aurignacian. An operational chain reconstruction with an attribute analysis is paired with a typological approach to the preparation and maintenance products based on artefacts defined as West European Aurignacian. The results of this study are investigated with multivariate statistics offering a methodological contribution. The data is subjected to a transformation into a distance matrix using the Gower distance and tested with the adonis-algorithm for significance. The results clearly indicate that the carinated items in Hayonim Cave did fully or partially function as cores. They are accompanied by diagnostic preparation- and- maintenance products known from the literature e.g. Thèmes bladelets. The statistical analysis indicates only a minor correlation with stratigraphy yet supports the techno-typological criteria applied for defining artefact categories (cores, debitage, tools), as well as the proposed differentiation of carinated 'core' types. The non-carinated cores in Hayonim Cave are characterised by a high variability in typology and reduction concepts. A curious similarity to the Levallois-concept is observed on some of the flake cores. It is therefore suggested that the frequent recycling of Middle Palaeolithic artefacts in the Levantine Aurignacian might have given the Aurignacian flint-knappers the opportunity to study the Levallois concept and apply an approximation of it in their own core reduction strategies. The notion that Palaeolithic flint-knappers actively observed former technological systems through the discarded artefacts directly opens up a new trajectory for the understanding of lithic reduction concept permanence. The conceptual diversification and variability in Hayonim Cave D indicate a highly dynamic period in the Levantine Upper Palaeolithic which increased the adaptive potential and promoted a rapid cultural change.

The Initial Upper Paleolithic from Tolbor-16, Mongolia: Characteristics of the Lithic Assemblage and Their Evolutionary Implications

According to fossil evidence, the Initial Upper Paleolithic (IUP) refers to archaeological assemblages associated with the early dispersal of Homo sapiens across Eurasia. These assemblages are often described as exhibiting a combination of Middle and Upper Paleolithic typo-technological features or, more broadly, as a technology in progression from the former to the latter. Genetic evidence indicates that as members of our species moved across Europe and Asia, they encountered Neanderthal, Denisovan, and possibly other local populations. At the Eurasian scale, the IUP shows considerable variation, but to what extent this corresponds to a relatively unified cultural package strictly associated with our species, or a suite of unrelated technologies reflecting the complex dynamics of a global population turnover, remains unclear. Like most archaeological assemblages, however, the IUP illustrates a combination of adaptive and normative behaviors, along with some stochastic variation. Here, we investigate what drives typo-technological variation within an IUP assemblage to identify traits relevant for larger scale inter-regional comparisons. Specifically, we describe a lithic assemblage dated to ca. 45 ka cal BP from the site of Tolbor-16 in northern Mongolia. We identify three defining aspects of the IUP at the site, namely variation in core shape and size, patterns of blade core reduction, and the presence of Middle Paleolithic typo-technological features. Our goal is to clarify the influence of dynamic reduction processes on assemblage composition and, within the variation observed, to identify typo-technological features that are relevant for inter-regional comparisons and scenarios of population dispersal.

Core Reduction Methods of Mizyn Industry of Epigravettian Techno-Complex

Mizyn is one of the main sites of the Epigravettian techno-complex of the Middle Dnipro Basin. One of the modern approaches to the study of the material culture of Upper Palaeolithic societies is the study of technological features of flintknapping. The purpose of this study is to determine the core reduction strategy of the Mizyn site in particular and the Mizyn industry in general. To achieve this goal, an attributional analysis of the artefacts from the lithic assemblage of excavation area no. 1 of the Mizyn site was carried out. Fragments of raw material, core-like pieces, and lamellar pieces have been analysed. This paper focuses on the study of the assemblage of core-like pieces, taking into account the imperfections of the 70-year-old field research methodology. The main outcome of this study was the elucidation of discrete core reduction strategies of the Mizyn site. Rounded raw material played a greater role in the production of blades from narrow flaking surface cores and sub-cylindrical cores (fig. 4). Narrow flaking surface cores (fig. 6) made from plate-like raw materials were used to produce blades and micro-blades. Blades were necessary blanks for making a “home” set of tools. Bladelets and micro-blades were used for hunting equipment. Both strategies are characterised by unidirectional splitting and the use of the hard hammer-stone. Crested and débordante lamellar pieces were required to maintain the convexity of the core’s flaking surface. The overhang trimming method was also used, most commonly for bladelets and micro-blade cores. The main reason for core discard was the occurrence of hinge fractures on the flaking surface, which were repaired by using an opposite striking platform. The same features of the lithic assemblage are found at the Barmaky site. As a result, discrete strategies of the core reduction are a typical feature for the Mizyn industry. As Barmaky and Mizyn are the oldest Epigravettian sites in the Middle Dnipro basin, this feature can be explained by a chronological factor. However, the choice of a strategy can also be explained by the regional characteristics of the landscape and the adaptation of the primary inhabitants to them.

Two new Later Stone Age sites from the Final Pleistocene in the Falémé Valley, eastern Senegal.

The understanding of cultural dynamics at work at the end of the Final Pleistocene in West Africa suffers from a significant lack of excavated and dated sites, particularly in the Sahelian and Sudanian ecozones. While the Later Stone Age shows varied behavioral developments in different parts of the continent, the chrono-cultural framework of this period remains largely unknown in West Africa. We report on archaeological, geomorphological, and chronological research on two Final Pleistocene Later Stone Age sites in the Falémé Valley, eastern Senegal. Optically stimulated luminescence ages place the site of Toumboura I-2017 between 17 ± 1 and 16 ± 1 ka and the Ravin de Sansandé site between 13 ± 1 ka and 12 ± 1.1 ka. The excavated lithics show typical Later Stone Age industries, characterized by chaînes opératoires of core reduction mainly producing flakes and bladelets as well as blades and laminar flakes. Segments dominate the toolkits but a few backed bladelets and end-scrapers on flake blanks were recognized. Local raw materials were used, with a preference for chert and quartz, as well as greywacke. These Later Stone Age lithic assemblages are the oldest known in Senegal so far and add to the small number of sites known in West Africa for this period, which are mainly located farther south, in sub-tropical ecozones. The Later Stone Age sites of the Falémé Valley are contemporaneous with typical Middle Stone Age technologies in Senegal dated to at least the Pleistocene/Holocene transition. Our results thus provide new archaeological evidence highlighting the complex cultural processes at work during the Final Pleistocene in West Africa.

New Data for Asymmetric Core Reduction in Western Tian Shan Piedmonts: The Ertash Sai 2 Open-Air Site

ABSTRACT This study describes a multi-proxy approach toward a newly discovered open-air loess site, Ertash Sai 2, located in the western piedmonts of the Tian Shan in Uzbekistan. Technological analyzes enabled the identification of an asymmetric core reduction scheme accompanied by a Levallois-like predetermined knapping scheme, along with the production of truncated-faceted pieces and burin-cores. Moreover, the results show a direct relationship between the presence of truncated-faceted pieces or burin-cores and both core reduction schemes, as long as truncated-faceted pieces were mostly produced from débordant blades and flakes. Chronostratigraphic studies enabled the precise chronology of the assemblage to be determined as 68–57 ka BP. This raises questions about the origins of traits usually associated with the Initial Upper Palaeolithic in Central Asia and their roots in local Levallois-based assemblages.

The Contribution of 2D and 3D Geometric Morphometrics to Lithic Taxonomies: Testing Discrete Categories of Backed Flakes from Recurrent Centripetal Core Reduction

AbstractPaleolithic lithic assemblages are usually dominated by flakes and display a high degree of morphological variability. When analyzing Paleolithic lithic assemblages, it is common to classify flakes into categories based on their morphological and technological features, which are linked to the position of the flake in the reduction sequence and how removals are organized in a given production method. For the analysis of Middle Paleolithic lithic assemblages, two categories of flakes are commonly identified: core–edge flakes and pseudo-Levallois points. A third type, core–edge flakes with a limited back, is also commonly found in the archaeological literature, providing an alternative category whose definition does not match the two previous types but shares many of their morphological and technological features. The present study addresses whether these three flakes constitute discrete categories based on their morphological and technological attributes. 2D and 3D geometric morphometrics are employed on an experimental set composed of the three categories of flakes to quantify morphological variation. Machine learning models and principal components biplots are used to test the discreteness of the categories. The results indicate that geometric morphometrics succeed in capturing the morphological and technological features that characterize each type of product. Pseudo-Levallois points have the highest discreteness of the three technological products, and while some degree of mixture exists between core edge flakes and core edge flakes with a limited back, they are also highly distinguishable. We conclude that the three categories are discrete and can be employed in technological lists of products for the analysis of lithic assemblages and that geometric morphometrics is useful for testing for the validity of categories. When testing these technological categories, we stress the need for well-defined and shared lithic analytical units to correctly identify and interpret the technical steps and decisions made by prehistoric knappers and to properly compare similarities and differences between stone tool assemblages. These are key aspects for current research in which open datasets are becoming more and more common and used to build interpretative techno-cultural models on large geographical scales. Now more than ever, lithic specialists are aware of the need to overcome differences in taxonomies between different school traditions.

Flexural behavior of two-layer reinforced concrete slab with hollow cores

Flexural behavior of a concrete slab system with an optimal weight-to-strength ratio comprising layered and hollow-core slab structures was investigated using two-layered slabs with hollow cores (LS/HCS). Six slabs with dimensions of 180, 450, and 1600 mm were tested experimentally and numerically using ANSYS software. Each layered slab comprises a 90-mm-thick lightweight concrete bottom layer and a 90-mm-thick high-strength concrete top layer. Three parameters were studied: core diameter (58, 86, and 110 mm), reinforcement ratio (0.37%, 0.53%, 0.95%), and treatment type (bonding agent, nails). Treatment types were analyzed via push-out testing; both nails and agents connected the slabs with sufficient bond strength. A control slab with 86-mm core diameter, shear-span-to-effective-depth ratio of 4, reinforcement ratio of 0.53%, and agent material was used. Concrete, steel bars, and loading support plates were modeled using SOLID65, LINK180, and SOLID185 elements, respectively. Analytical results were validated experimentally. A parametric study analyzed other parameters affecting LS/HCS behavior, including compressive strength, opening numbers, core shape, applied loading type, added top steel reinforcement, slab type, and slab height. Core diameter reduction, increased reinforcement ratios, and using nails enhanced the failure load. The LS/HCS gives an optimum weight-to-strength ratio with a 33.672% reduction compared with solid slabs.

Virtual reconstruction of stone tool refittings by using 3D modelling and the Blender Engine: The application of the "ReViBE" protocol to the archaeological record.

Visual representation of material culture plays a crucial role in prehistoric archaeology, from academic research to public outreach and communication. Scientific illustration is a valuable tool for visualising lithic artefacts and refittings, where technical attributes must be drawn to enhance our understanding of their significance. However, the representation of lithic refittings, which involve dynamic and sequential transformations of a volume, requires an alternative approach to traditional two-dimensional models such as photography or illustration. Advances in imaging technologies have improved our ability to capture and communicate the multifaceted nature of archaeological artefacts. In this context, we present the ReViBE protocol (Refitting Visualisation using Blender Engine), which integrates photogrammetry, 3D modelling and the animation software Blender© for the virtual representation of lithic refittings. This protocol allows the sequential study of core reduction phases and their associated flakes, as well as other aspects related to knapping decision making (core rotations, surface modifications, and direction and position of impact points). Thus, this method allows the visualisation of techno-cognitive aspects involved in core reduction through a step-by-step animation process. In addition, the 3D models and virtual reconstructions generated by ReViBE can be accessed through open repositories, in line with the principles of open science and FAIR (Findable, Accessible, Interoperable, and Reusable) data. This accessibility ensures that data on lithic technology and human behaviour are widely available, promoting transparency and knowledge sharing, and enabling remote lithic analysis. This in turn breaks down geographical barriers and encourages scientific collaboration.

Establishing a new workflow in the study of core reduction intensity and distribution

New methodological approaches focused on studying the reduction and use-life of stone tools have emerged in recent years, enabling researchers to move beyond strict technical and technological characterizations and explore specific aspects of occupation dynamics and economic management of resources. Previous studies have shown the importance of reduction distributions of individual measurements rather than averaged values. In this sense, survival analysis, and more specifically Weibull distributions, are one of the main inferential tools used in reduction studies. However, the resolution of Weibull distribution obtained from different methods has not been tested experimentally. In this paper, we present an evaluation of some of the main methods used in the study of core reduction intensity, such as the Volumetric Reconstruction Method, the Scar Density Index, and the non-cortical surface percentage. Our results show 1) strong and positive correlations between these approaches and actual reduction intensity, 2) similar Weibull distributions for non-cortical surface percentage, Volumetric Reconstruction Method, and logarithmic transformation of Scar Density Index. In addition, 3) the results from each method show a similar intra-assemblage variation, with a high percentage of agreement between them. As a result, all the evaluated proposals are useful and reliable methods for estimating the degree of reduction. Finally, a workflow is proposed for approaching reduction in archaeological assemblages by integrating different methods in the same study.

Facets of Variation: Macrocrystalline quartz reduction at Moolarben, central NSW, Australia

Macrocrystalline quartz is an abundant raw material used widely for artefact manufacture. In Australia its procurement, reduction and use are now considered more complex than previously thought. The analysis of a mid-late Holocene assemblage from Moolarben in eastern Australia demonstrates how geoarchaeological variability influences the manufacture of macrocrystalline quartz artefacts. The different flaking proprieties of the three available macrocrystalline quartz varieties (opaque milky, semi-transparent milky and crystal), along with the type of source, influenced core reduction as well as the resulting flake form and its use. Moreover, to counter the costs of flaking problems of macrocrystalline quartz, different reduction strategies were used for cores obtained from primary reef/vein outcrops and those from secondary sources (water-rolled alluvial pebbles). The systematic reduction strategies used to prepare cores and remove the elongated flakes suitable for backed artefacts represent an adaption of already established flaking strategies, and suggest that the disappearance of backed artefacts in Late Holocene assemblages from eastern Australia (associated with an increase in the use of macrocrystalline quartz in some areas), did not represent a dramatic change in technology, but rather an effective and significant innovation which ultimately meant that backing was no longer required. This technological shift is also reflected in the benefits of flaking a locally abundant material which retains a strong and sharp working edge. Measuring geoarchaeological variability adds greater insights into the costs and benefits of manufacturing macrocrystalline quartz artefacts, and these insights are applicable to studies worldwide.

Unravelling technological behaviors through core reduction intensity. The case of the early Protoaurignacian assemblage from Fumane Cave

This paper investigates core reduction intensity in the early Protoaurignacian lithic assemblage from Fumane Cave in northeastern Italy. Reduction intensity serves as a key tool to characterize blank selection strategies, raw material management, and the variability of knapping strategies throughout the reduction sequence by reconstructing the operatory field of core assemblages. Finally, it also aids in addressing the relationship between blades and bladelets, providing valuable insights into the behavioral and chrono-cultural significance of laminar productions within the Aurignacian technocomplex. To achieve these research goals, experimental work employing 3D scanning technology was conducted. This facilitated the comparison of different methods and variables for measuring reduction intensity, including the percentage of non-cortical surface, the Scar Density Index (SDI), and a novel adaptation of the Volumetric Reconstruction Method (VRM). Results demonstrate the effectiveness and potential of adapting the VRM for the study of reduction intensity in Upper Paleolithic laminar cores, and the provided R scripts and datasets will enable this method to be applied to other contexts with minimal need for modification to the workflow. Analysis of reduction intensity measures applied to the Protoaurignacian assemblage from Fumane Cave reveals slight variations based on factors such as the abundance and proximity of selected raw materials for blank production. Notably, the most prevalent raw material variety, the Maiolica, yields a higher number of less reduced cores, while reduction levels across all cores discarded at the site remain relatively high. The observed variability in the operatory field and the interrelation between blade and bladelet productions underscore the complexity and flexibility of Protoaurignacian behavior. This inherent complexity challenges any definitive separation between the operatory fields of blade and bladelet productions. These findings are particularly important to emphasize the importance of considering reduction intensity when examining technological variability and human behavior in Aurignacian studies. The proposed adaptation of the VRM and the effective combination with other measures of reduction, promises to allow future research to incorporate reduction intensity as a vital temporal component within studies on stone tool production. This integration offers a pathway to enhancing our understanding of the adaptive behaviors exhibited by Homo sapiens across diverse ecological settings and provides a clearer framework for better framing the development of the Upper Paleolithic.

40,000 years of technological continuity and change at Matja Kuru 2, Timor-Leste

Timor-Leste is known for long-term continuity in lithic manufacturing techniques that span at least the last 44,000 years. Here we confirm this pattern of long-term continuity in stone tool manufacture at the site of Matja Kuru 2, located on Timor-Leste close to the freshwater Lake Ira Lalaro. The lithic assemblage is characterised by high reduction intensity and frequent use of bipolar, ‘core-on-flake’, discoidal and multiplatform core reduction to produce small flakes while high levels of retouch, heat damage and breakage. While continuity is an important feature of the assemblage, we also document important changes in technology, raw material selection and recycling/extension strategies over time. We posit that the long periods of absence at MK2 may coincide with drier phases when Ira Lalaro likely dried and that more extensive use of the cave occurs during wet phases with attendant lake high conditions. The lithic assemblage indicates increased mobility and individual provisioning in the transitions between these phases of site use and abandonment. The Matja Kuru 2 lithic assemblage also reveals the earliest known evidence yet found for obsidian and possible inter-island transport in Wallacea.

Exploring the Gross-Edge Curvature of Experimentally Produced Preferential Levallois Debitage

ABSTRACT Flaked stone reduced via a Levallois, or Levallois-like, sequence potentially provided benefits to hominins in terms of flake morphology and economy relative to other sequences. But such benefits did not come without costs. Here, we contribute to ongoing debates regarding Levallois technology by assessing the gross-edge curvature of experimentally produced Levallois debitage and Preferential Levallois Flake (PLF) edges. Previous experiments have shown that as gross-edge curvature increases, cutting efficiency decreases. As such, our results allow us to evaluate standardized gross-edge curvature throughout multiple Preferential Levallois Core reduction stages. Also, among several results, we show that as Levallois debitage size decreases, so too does gross-edge curvature, suggesting that knappers pursuing a Levallois core to exhaustion will not be penalized in terms of this feature.

Small tool production in the Howiesons Poort: a view from Montagu Cave, South Africa

ABSTRACT In southern Africa, the Howiesons Poort is one of the earliest technocomplexes in which small blades and bladelets were systematically produced and retouched into formal tools. While the presence of small lithic artefacts in an assemblage is well-documented, little is known about production pathways. This paper reports on the analysis of the lithic assemblage from Horizon 6/7 of Charles Keller’s excavations of Montagu Cave, South Africa, to evaluate how raw material and decision-making affects the size of stone tools in Howiesons Poort assemblages. It addresses the following questions: how were small blades produced? Was it a deliberate choice or a constraint imposed by raw material availability? Results show branching modes of production for large and small blanks beginning with raw material acquisition. The independent production of small blanks is reinforced by the presence of cores on flakes in the assemblage. However, a relatively standardised core reduction process was used consistently, regardless of core size. The main technological and typological features observed in Horizon 6/7 are in line with other known Howiesons Poort assemblages. Considered as a whole, these observations highlight the consistency of Howiesons Poort blade technology and the deliberate production of small blanks and tools.

Precise tuning of silica pore length and pore diameter on silica-encapsulated gold core–shell nanoparticles and catalytic impact

The ability to individually tune the pore length and pore diameter of silica-encapsulated gold core–shell nanoparticles (CSNPs) via a seeded encapsulation method is demonstrated and their impact on catalysis determined. Reducing the solvent volume during the shell growth phase resulted in CSNPs with shells of increasing thickness from 75 nm to 202 nm, following a linear relationship. The addition of 1, 3, 5-triisopropylbenzene (TIB) during synthesis increased the average pore diameter from 25 Å to 32 Å by swelling the pore template, swelling further to 38 Å when adding both TIB and n-decane. By decoupling the gold core reduction and silica condensation stages, gold core diameters were largely unaffected by silica growth reaction conditions. This was achieved by encapsulating CTAB-stabilized nanoparticles rather than reducing and stabilizing the nanoparticles during silica condensation. When used to catalyze solvent-free benzyl alcohol oxidation, it was found that CSNPs with increasing shell thicknesses demonstrated increased formation of the desirable aldehyde product, holding the undesired ester product yield constant. In contrast, CSNPs with increasing pore diameter exhibit increased formation of both aldehyde and ester products unselectively. These results—uniquely observed through the parametric isolation of pore length and diameter—suggest the reactant concentration at the pore wall due to hydrogen bonding, forming concentric “microphases” within the pores.