Marine Wojcieszak | Royal Institute for Cultural Heritage, Brussels (IRPA / KIK) (original) (raw)

Papers by Marine Wojcieszak

Radiocarbon

Lacquerwork technologies comprise multiple techniques depending on countries, time, and tradition... more Lacquerwork technologies comprise multiple techniques depending on countries, time, and traditions. Carved Asian lacquers applied on wooden objects consist of multiple thin uncolored or pigmented layers spread over the surface. To radiocarbon (14C) date these types of objects, often only the wooden structure is used. Here we report on a set of carved lacquered objects that were dated based on stylistic form, 14C dating of the wooden structure and of the Asian lacquers. THM-Py-GC-MS and micro-Raman spectroscopy were used to confirm the molecular composition of the lacquers and helped assessing the pretreatment protocol. The lacquers analyzed contained between 20 and 50% wt carbon, thus 2–5 mg of sample were necessary for 14C dating. The dates obtained on wood and lacquers showed a reliable correlation. The results suggest that, in most cases, it is sufficient to sample a part of the lacquer layers to date an object. We advise to perform an acid pretreatment followed by a successive s...

Quaternary Science Reviews

Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in a... more Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in all archaeological members, with the exception of the oldest members 5 WA and 6 BS (>227,000 years ago). They were recovered in relatively high frequencies in Members 4 WA, 4 BS, 1 RGBS and 3 WA. The shell fragments present a range of colours from lustrous beige to brown and matt grey. The colour variability can occur when shell is heated. This possibility was explored here through experimental heating of giant land snail shell fragments (Achatinidae, Metachatina kraussi - brown lipped agate snail) in a muffle furnace from 200 to 550 °C for different lengths of time. Colour change, weight loss, and shattering of the heated samples were recorded. Transformation of aragonite into calcite and the occurrence of organic material was investigated by means of Infrared and Raman spectroscopy. Scanning electron microscopy was also used on selected specimens to help identify heat-induced transformation as opposed to taphonomic alteration. The identification on archaeological fragments of features produced by experimentally heating shells at high temperatures or for long periods has led us, after discarding alternative hypotheses, to conclude that large African land snails were systematically brought to the site by humans, roasted and consumed, starting from 170,000 years ago and, more intensively between 160,000 and 70,000 years ago. Border Cave is at present the earliest known site at which this subsistence strategy is recorded. Previous research has shown that charred whole rhizomes and fragments of edible Hypoxis angustifolia were also brought to Border Cave to be roasted and shared at the site. Thus, evidence from both the rhizomes and snails in Border Cave supports an interpretation of members of the group provisioning others at a home base, which gives us a glimpse into the complex social life of early Homo sapiens.

Quaternary Science Reviews, 2023

Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in a... more Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in all archaeological members, with the exception of the oldest members 5 WA and 6 BS (>227,000 years ago). They were recovered in relatively high frequencies in Members 4 WA, 4 BS, 1 RGBS and 3 WA. The shell fragments present a range of colours from lustrous beige to brown and matt grey. The colour variability can occur when shell is heated. This possibility was explored here through experimental heating of giant land snail shell fragments (Achatinidae, Metachatina kraussi - brown lipped agate snail) in a muffle furnace from 200 to 550 °C for different lengths of time. Colour change, weight loss, and shattering of the heated samples were recorded. Transformation of aragonite into calcite and the occurrence of organic material was investigated by means of Infrared and Raman spectroscopy. Scanning electron microscopy was also used on selected specimens to help identify heat-induced transformation as opposed to taphonomic alteration. The identification on archaeological fragments of features produced by experimentally heating shells at high temperatures or for long periods has led us, after discarding alternative hypotheses, to conclude that large African land snails were systematically brought to the site by humans, roasted and consumed, starting from 170,000 years ago and, more intensively between 160,000 and 70,000 years ago. Border Cave is at present the earliest known site at which this subsistence strategy is recorded. Previous research has shown that charred whole rhizomes and fragments of edible Hypoxis angustifolia were also brought to Border Cave to be roasted and shared at the site. Thus, evidence from both the rhizomes and snails in Border Cave supports an interpretation of members of the group provisioning others at a home base, which gives us a glimpse into the complex social life of early Homo sapiens.

Quaternary Science Reviews

Border Cave (BC) has accumulated over 200,000 years of archaeological deposits that document rema... more Border Cave (BC) has accumulated over 200,000 years of archaeological deposits that document remarkable evidence of human behaviour during the Middle and Later Stone Age. For nearly fifty years, researchers have relied on the stratigraphic framework established by Peter Beaumont in 1973, in which the deposits are lithostratigraphically categorized into a sequence of alternating 'Brown Sand' (BS) and 'White Ash' (WA) members. Geoarchaeological work in the 1970s focused on stratigraphic sequencing of the anthropogenic assemblages, and proposed broad correlations between autogenic contributions and environmental conditions. The research presented here was undertaken as part of a new excavation campaign at Border Cave started in 2015 under the direction of Backwell at al.. Reexamining the stratigraphic context of the deposits and assessing site formation processes are among the key goals of this project; this will enable finer-scale intra-and inter-member comparative analyses of the artefacts and ecofacts recovered at the site. In this paper, we apply a facies and allostratigraphic analysis approach to assess the stratigraphic sequence exposed through the Backwell et al. excavations. We also provide an initial assessment of the prevailing site formation processes active in the deposition and modification of the sediments. The geoarchaeological data are integrated with new zooarchaeological and taphonomic evidence in order to explore inter-and intra-unit patterns throughout the sequence. Results of this work are: (1) exposed sediments can be broadly correlated to members of the Beaumont sequence; (2) we clearly define member boundaries, reassess member stratigraphic complexity and recognise finer intramember layering; (3) geoarchaeological and taphonomic studies demonstrate that the sediments have been subjected to greater post-depositional disturbance than was previously recognized and affect all levels of the sequence; (4) overall, faunal density at BC appears to be much lower than that at other Middle Stone Age sites such as Blombos and Sibudu; (5) multiproxy analysis suggests that WA and BS members have distinctive taphonomic histories that cross-cut the identified archaeological industries. As such, caution is warranted when combining BS and WA members for analysis of artefacts and ecofacts.

Radiocarbon

Chronological and stratigraphic frameworks are of the utmost importance for Upper Paleolithic arc... more Chronological and stratigraphic frameworks are of the utmost importance for Upper Paleolithic archaeology, physical anthropology, and ecology. Wide ranging radiocarbon (14C) dates were previously obtained for the Sungir burial complex in the central part of European Russia, which is well-known as the richest funeral Paleolithic assemblage in the world yet recorded. The major problem was the contamination caused by consolidants used during the recovery of human bones in the 1960s. The stratigraphy and spatial structure of the Sungir site were also not well understood previously. New radiocarbon and stable isotope data are generated for the Sungir burials. While some dates were younger due to incomplete removal of contamination, the XAD 14C age on S-1 burial (ca. 29,780 BP) was found to be statistically the same as the previously performed HYP 14C age for this burial (ca. 28,890 BP). Four animal bones found in cultural layer below the burial date to ca. 28,800–30,140 BP, suggesting th...

New excavations at Border Cave use high-resolution techniques, including FT-IR, for sediment samp... more New excavations at Border Cave use high-resolution techniques, including FT-IR, for sediment samples and thin sections of micromorphology blocks from stratigraphy. These show that sediments have different moisture regimes, both spatially and chronologically. The site preserves desiccated grass bedding in multiple layers and they, along with seeds, rhizomes, and charcoal, provide a profile of palaeo-vegetation through time. A bushveld vegetation community is implied before 100,000 years ago. The density of lithics varies considerably through time, with high frequencies occurring before 100,000 years ago where a putative MSA 1/Pietersburg Industry was recovered. The highest percentage frequencies of blades and blade fragments were found here. In Members 1 BS and 1 WA, called Early Later Stone Age by Beaumont, we recovered large flakes from multifacial cores. Local rhyolite was the most common rock used for making stone tools, but siliceous minerals were popular in the upper members.

ABSTRACT The ‘best’ silk fibres (natural polyamide), present a very high breaking resistance but ... more ABSTRACT The ‘best’ silk fibres (natural polyamide), present a very high breaking resistance but also a huge variability (typically 200-1000 MPa). Films made of Bombyx mori fibroin showed good biocompatibility suitable for biomedical applications, as silk was used as suture material for centuries. Solubilisation process degrades macromolecules and mechanical properties of regenerated silk, ultimate strain and stress, are drastically lower (a few %) than those measured for raw fibres. The goal of this work is to improve tensile mechanical properties of regenerated silk films by silk fibres reinforcement, degummed or not. Degummed fibres (i.e. without sericin coating) are dissolved and dialysed in order to obtain a liquid/gel more or less viscous followed by evaporation to obtain silk matrix. Structure and orientation modifications of fibroin macromolecules are monitored by Raman spectroscopy. The incorporation of a few fibre % vol improved the breaking resistance and dissipation. The mechanical behaviour of regenerated silk-base materials appeared as being dependent from chemical treatment and many parameters have to be optimized.

Journal of Materials Science, 2017

AbstractWe report tensile tests for the dragline silk of Nephila madagascariensis golden silk spi... more AbstractWe report tensile tests for the dragline silk of Nephila madagascariensis golden silk spider strained at 7% min−1. The average Young’s modulus (8.2 GPa), work of fracture (250 MJ m−3) and ultimate strain (28%) fall in the same range as for most previously tested spider silks. The average strength is rather low yet (645 MPa in the engineering convention), even in comparison with other Nephila spiders having similar secondary structures (as controlled by polarized Raman microscopy). The scattering of stress/strain failure values is often seen as an obstacle for the unequivocal characterization of silks, but our study evidences a great shape similarity between normalized tensile curves. The so-called strain-hardening region may be divided into a nonlinear regime (nLHR) and a linear one (LHR). The nLHR tends to disappear on averaged spectra, suggesting that it does not correspond to any specific mechanism. Instead, we propose that the plastic deformation to linear hardening tran...

Archaeological and Anthropological Sciences, 2020

Ostrich eggshell and gastropod shell beads provide important evidence for understanding how past ... more Ostrich eggshell and gastropod shell beads provide important evidence for understanding how past peoples decorated and cultured their bodies and may also be used as proxy evidence for interpreting the nature and extent of past social networks. This study focuses on the ostrich eggshell and gastropod shell bead assemblages from the terminal Pleistocene (~ 13.5 to 11.6 ka) and mid-Holocene (~ 7.3 to 6.7 ka) occupations from Grassridge Rockshelter, South Africa. We present results from a multi-method approach to understanding bead manufacture and use that combines a technological analysis of the bead assemblages with Raman spectroscopy. Raman spectroscopy analyses were conducted on surface residues identified on the beads, ochre pieces, a grooved stone, and sediment samples, and provide further insight into past behaviours and taphonomy, as well as modern contaminants. Results indicate that ostrich eggshell beads were manufactured at Grassridge during both occupations, and that bead size changed through time. Use-wear and residue analyses demonstrate the complex taphonomy associated with bead studies from archaeological contexts, and the need for further taphonomic research. These analyses also suggest that some ostrich eggshell and Nassarius beads were potentially worn against ochred surfaces, such as skin or hide, as evidenced by the amount and location of the ochreous residues identified on the beads.

Radiocarbon, 2020

The Royal Institute for Cultural Heritage (RICH) radiocarbon (14C) laboratory in Brussels, Belgiu... more The Royal Institute for Cultural Heritage (RICH) radiocarbon (14C) laboratory in Brussels, Belgium, has acquired experience for pretreating samples with 60 years of involvement in 14C dating, and the implementation of routine protocols. These procedures as applied to wood, seeds, charred materials, bones, ivory, textiles (silk, wool, cotton, linen), paper, shells, cremated bones, mortars, lead carbonates, sediments, etc. are described in detail in this paper. They are evaluated against reference materials.

Journal of Raman Spectroscopy, 2019

A recent study using the combination of optical microscopy and Raman spectroscopy revealed the pr... more A recent study using the combination of optical microscopy and Raman spectroscopy revealed the presence of bright yellow residues of lead (II) chromate associated with grinding striations on a 58,000‐year‐old grindstone excavated at Sibudu rock shelter in South Africa. Lead (II) chromate (PbCrO4) exists in nature as the rare mineral crocoite, however was available as the synthetic pigment, chrome yellow, from the 19th century. At the time of the residue analysis on the grindstone, it was not possible to determine whether the yellow residues were due to modern contamination or a result of ancient use. Careful analyses of the excavation protocol followed at Sibudu rock shelter and all implements that might possibly have been in contact with the grindstone after excavation identified yellow spray paint as a possible origin of the contamination. Here, we performed experimental grinding of the mineral crocoite on a sandstone slab, sprayed yellow paint on rhyolite and compared optical microscopy and Raman spectroscopic analysis results to the archaeological sample. The optical appearance of the archaeological residues, the absence of associated minerals of crocoite, and the presence of organic matter mixed with lead chromate demonstrate that the residues on the archaeological grindstone stem from modern contamination. This paper draws attention to contamination issues originating from excavation practices.

Journal of Raman Spectroscopy, 2018

Despite their high potential for understanding past human behaviours, the study of grindstones is... more Despite their high potential for understanding past human behaviours, the study of grindstones is limited in the literature compared with other forms of lithic tools. This paper reports the combination of optical microscopy and Raman microspectroscopy for understanding the uses of a selection of six grindstones from the post-Howiesons Poort layers at Sibudu, South Africa, dating to 58,000 years ago. Five of the specimens exhibit numerous red haematite stains which imply red ochre processing. Nevertheless, each artefact seems to have been used for a specific task. For example, the smallest grindstone was used for a combination of tasks—ochre, bone, and organic matter processing. The distinction between use residues, sediment contamination, secondary mineral formation, modern contamination, and components included in the sandstone that the grindstones are made from is discussed.

Journal of Composite Materials, 2017

Silk is a biocompatible material with remarkable mechanical properties. A variety of composite ma... more Silk is a biocompatible material with remarkable mechanical properties. A variety of composite materials using silk as a matrix or for reinforcement have been prepared for many biological applications. However, although a range of composites containing silk have been designed, the mechanical properties achieved for the regenerated silk (solubilisation + film/matrix or fibre production) remain relatively weak (strength: 30–50 MPa). In this study, by combining the high ultimate strength (up to 1 GPa) of natural silk fibres and the chemical properties of regenerated silk, we developed a composite based on silk alone. We investigated how to improve the tensile mechanical properties of silk matrices derived from Bombyx mori silkworms by film processing and by incorporating silk fibres, either natural or degummed, that is, without the sericin coating. The structure and orientation modifications of fibroin macromolecules within the matrix were monitored by Raman spectroscopy; unexpectedly ...

Journal of Field Archaeology, 2018

ABSTRACT New excavations at Border Cave use high-resolution techniques, including FT-IR, for sedi... more ABSTRACT New excavations at Border Cave use high-resolution techniques, including FT-IR, for sediment samples and thin sections of micromorphology blocks from stratigraphy. These show that sediments have different moisture regimes, both spatially and chronologically. The site preserves desiccated grass bedding in multiple layers and they, along with seeds, rhizomes, and charcoal, provide a profile of palaeo-vegetation through time. A bushveld vegetation community is implied before 100,000 years ago. The density of lithics varies considerably through time, with high frequencies occurring before 100,000 years ago where a putative MSA 1/Pietersburg Industry was recovered. The highest percentage frequencies of blades and blade fragments were found here. In Members 1 BS and 1 WA, called Early Later Stone Age by Beaumont, we recovered large flakes from multifacial cores. Local rhyolite was the most common rock used for making stone tools, but siliceous minerals were popular in the upper members.

Additional file 1. Additional figures and table.

Radiocarbon

Lacquerwork technologies comprise multiple techniques depending on countries, time, and tradition... more Lacquerwork technologies comprise multiple techniques depending on countries, time, and traditions. Carved Asian lacquers applied on wooden objects consist of multiple thin uncolored or pigmented layers spread over the surface. To radiocarbon (14C) date these types of objects, often only the wooden structure is used. Here we report on a set of carved lacquered objects that were dated based on stylistic form, 14C dating of the wooden structure and of the Asian lacquers. THM-Py-GC-MS and micro-Raman spectroscopy were used to confirm the molecular composition of the lacquers and helped assessing the pretreatment protocol. The lacquers analyzed contained between 20 and 50% wt carbon, thus 2–5 mg of sample were necessary for 14C dating. The dates obtained on wood and lacquers showed a reliable correlation. The results suggest that, in most cases, it is sufficient to sample a part of the lacquer layers to date an object. We advise to perform an acid pretreatment followed by a successive s...

Quaternary Science Reviews

Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in a... more Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in all archaeological members, with the exception of the oldest members 5 WA and 6 BS (>227,000 years ago). They were recovered in relatively high frequencies in Members 4 WA, 4 BS, 1 RGBS and 3 WA. The shell fragments present a range of colours from lustrous beige to brown and matt grey. The colour variability can occur when shell is heated. This possibility was explored here through experimental heating of giant land snail shell fragments (Achatinidae, Metachatina kraussi - brown lipped agate snail) in a muffle furnace from 200 to 550 °C for different lengths of time. Colour change, weight loss, and shattering of the heated samples were recorded. Transformation of aragonite into calcite and the occurrence of organic material was investigated by means of Infrared and Raman spectroscopy. Scanning electron microscopy was also used on selected specimens to help identify heat-induced transformation as opposed to taphonomic alteration. The identification on archaeological fragments of features produced by experimentally heating shells at high temperatures or for long periods has led us, after discarding alternative hypotheses, to conclude that large African land snails were systematically brought to the site by humans, roasted and consumed, starting from 170,000 years ago and, more intensively between 160,000 and 70,000 years ago. Border Cave is at present the earliest known site at which this subsistence strategy is recorded. Previous research has shown that charred whole rhizomes and fragments of edible Hypoxis angustifolia were also brought to Border Cave to be roasted and shared at the site. Thus, evidence from both the rhizomes and snails in Border Cave supports an interpretation of members of the group provisioning others at a home base, which gives us a glimpse into the complex social life of early Homo sapiens.

Quaternary Science Reviews, 2023

Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in a... more Fragments of land snail (Achatinidae) shell were found at Border Cave in varying proportions in all archaeological members, with the exception of the oldest members 5 WA and 6 BS (>227,000 years ago). They were recovered in relatively high frequencies in Members 4 WA, 4 BS, 1 RGBS and 3 WA. The shell fragments present a range of colours from lustrous beige to brown and matt grey. The colour variability can occur when shell is heated. This possibility was explored here through experimental heating of giant land snail shell fragments (Achatinidae, Metachatina kraussi - brown lipped agate snail) in a muffle furnace from 200 to 550 °C for different lengths of time. Colour change, weight loss, and shattering of the heated samples were recorded. Transformation of aragonite into calcite and the occurrence of organic material was investigated by means of Infrared and Raman spectroscopy. Scanning electron microscopy was also used on selected specimens to help identify heat-induced transformation as opposed to taphonomic alteration. The identification on archaeological fragments of features produced by experimentally heating shells at high temperatures or for long periods has led us, after discarding alternative hypotheses, to conclude that large African land snails were systematically brought to the site by humans, roasted and consumed, starting from 170,000 years ago and, more intensively between 160,000 and 70,000 years ago. Border Cave is at present the earliest known site at which this subsistence strategy is recorded. Previous research has shown that charred whole rhizomes and fragments of edible Hypoxis angustifolia were also brought to Border Cave to be roasted and shared at the site. Thus, evidence from both the rhizomes and snails in Border Cave supports an interpretation of members of the group provisioning others at a home base, which gives us a glimpse into the complex social life of early Homo sapiens.

Quaternary Science Reviews

Border Cave (BC) has accumulated over 200,000 years of archaeological deposits that document rema... more Border Cave (BC) has accumulated over 200,000 years of archaeological deposits that document remarkable evidence of human behaviour during the Middle and Later Stone Age. For nearly fifty years, researchers have relied on the stratigraphic framework established by Peter Beaumont in 1973, in which the deposits are lithostratigraphically categorized into a sequence of alternating 'Brown Sand' (BS) and 'White Ash' (WA) members. Geoarchaeological work in the 1970s focused on stratigraphic sequencing of the anthropogenic assemblages, and proposed broad correlations between autogenic contributions and environmental conditions. The research presented here was undertaken as part of a new excavation campaign at Border Cave started in 2015 under the direction of Backwell at al.. Reexamining the stratigraphic context of the deposits and assessing site formation processes are among the key goals of this project; this will enable finer-scale intra-and inter-member comparative analyses of the artefacts and ecofacts recovered at the site. In this paper, we apply a facies and allostratigraphic analysis approach to assess the stratigraphic sequence exposed through the Backwell et al. excavations. We also provide an initial assessment of the prevailing site formation processes active in the deposition and modification of the sediments. The geoarchaeological data are integrated with new zooarchaeological and taphonomic evidence in order to explore inter-and intra-unit patterns throughout the sequence. Results of this work are: (1) exposed sediments can be broadly correlated to members of the Beaumont sequence; (2) we clearly define member boundaries, reassess member stratigraphic complexity and recognise finer intramember layering; (3) geoarchaeological and taphonomic studies demonstrate that the sediments have been subjected to greater post-depositional disturbance than was previously recognized and affect all levels of the sequence; (4) overall, faunal density at BC appears to be much lower than that at other Middle Stone Age sites such as Blombos and Sibudu; (5) multiproxy analysis suggests that WA and BS members have distinctive taphonomic histories that cross-cut the identified archaeological industries. As such, caution is warranted when combining BS and WA members for analysis of artefacts and ecofacts.

Radiocarbon

Chronological and stratigraphic frameworks are of the utmost importance for Upper Paleolithic arc... more Chronological and stratigraphic frameworks are of the utmost importance for Upper Paleolithic archaeology, physical anthropology, and ecology. Wide ranging radiocarbon (14C) dates were previously obtained for the Sungir burial complex in the central part of European Russia, which is well-known as the richest funeral Paleolithic assemblage in the world yet recorded. The major problem was the contamination caused by consolidants used during the recovery of human bones in the 1960s. The stratigraphy and spatial structure of the Sungir site were also not well understood previously. New radiocarbon and stable isotope data are generated for the Sungir burials. While some dates were younger due to incomplete removal of contamination, the XAD 14C age on S-1 burial (ca. 29,780 BP) was found to be statistically the same as the previously performed HYP 14C age for this burial (ca. 28,890 BP). Four animal bones found in cultural layer below the burial date to ca. 28,800–30,140 BP, suggesting th...

New excavations at Border Cave use high-resolution techniques, including FT-IR, for sediment samp... more New excavations at Border Cave use high-resolution techniques, including FT-IR, for sediment samples and thin sections of micromorphology blocks from stratigraphy. These show that sediments have different moisture regimes, both spatially and chronologically. The site preserves desiccated grass bedding in multiple layers and they, along with seeds, rhizomes, and charcoal, provide a profile of palaeo-vegetation through time. A bushveld vegetation community is implied before 100,000 years ago. The density of lithics varies considerably through time, with high frequencies occurring before 100,000 years ago where a putative MSA 1/Pietersburg Industry was recovered. The highest percentage frequencies of blades and blade fragments were found here. In Members 1 BS and 1 WA, called Early Later Stone Age by Beaumont, we recovered large flakes from multifacial cores. Local rhyolite was the most common rock used for making stone tools, but siliceous minerals were popular in the upper members.

ABSTRACT The ‘best’ silk fibres (natural polyamide), present a very high breaking resistance but ... more ABSTRACT The ‘best’ silk fibres (natural polyamide), present a very high breaking resistance but also a huge variability (typically 200-1000 MPa). Films made of Bombyx mori fibroin showed good biocompatibility suitable for biomedical applications, as silk was used as suture material for centuries. Solubilisation process degrades macromolecules and mechanical properties of regenerated silk, ultimate strain and stress, are drastically lower (a few %) than those measured for raw fibres. The goal of this work is to improve tensile mechanical properties of regenerated silk films by silk fibres reinforcement, degummed or not. Degummed fibres (i.e. without sericin coating) are dissolved and dialysed in order to obtain a liquid/gel more or less viscous followed by evaporation to obtain silk matrix. Structure and orientation modifications of fibroin macromolecules are monitored by Raman spectroscopy. The incorporation of a few fibre % vol improved the breaking resistance and dissipation. The mechanical behaviour of regenerated silk-base materials appeared as being dependent from chemical treatment and many parameters have to be optimized.

Journal of Materials Science, 2017

AbstractWe report tensile tests for the dragline silk of Nephila madagascariensis golden silk spi... more AbstractWe report tensile tests for the dragline silk of Nephila madagascariensis golden silk spider strained at 7% min−1. The average Young’s modulus (8.2 GPa), work of fracture (250 MJ m−3) and ultimate strain (28%) fall in the same range as for most previously tested spider silks. The average strength is rather low yet (645 MPa in the engineering convention), even in comparison with other Nephila spiders having similar secondary structures (as controlled by polarized Raman microscopy). The scattering of stress/strain failure values is often seen as an obstacle for the unequivocal characterization of silks, but our study evidences a great shape similarity between normalized tensile curves. The so-called strain-hardening region may be divided into a nonlinear regime (nLHR) and a linear one (LHR). The nLHR tends to disappear on averaged spectra, suggesting that it does not correspond to any specific mechanism. Instead, we propose that the plastic deformation to linear hardening tran...

Archaeological and Anthropological Sciences, 2020

Ostrich eggshell and gastropod shell beads provide important evidence for understanding how past ... more Ostrich eggshell and gastropod shell beads provide important evidence for understanding how past peoples decorated and cultured their bodies and may also be used as proxy evidence for interpreting the nature and extent of past social networks. This study focuses on the ostrich eggshell and gastropod shell bead assemblages from the terminal Pleistocene (~ 13.5 to 11.6 ka) and mid-Holocene (~ 7.3 to 6.7 ka) occupations from Grassridge Rockshelter, South Africa. We present results from a multi-method approach to understanding bead manufacture and use that combines a technological analysis of the bead assemblages with Raman spectroscopy. Raman spectroscopy analyses were conducted on surface residues identified on the beads, ochre pieces, a grooved stone, and sediment samples, and provide further insight into past behaviours and taphonomy, as well as modern contaminants. Results indicate that ostrich eggshell beads were manufactured at Grassridge during both occupations, and that bead size changed through time. Use-wear and residue analyses demonstrate the complex taphonomy associated with bead studies from archaeological contexts, and the need for further taphonomic research. These analyses also suggest that some ostrich eggshell and Nassarius beads were potentially worn against ochred surfaces, such as skin or hide, as evidenced by the amount and location of the ochreous residues identified on the beads.

Radiocarbon, 2020

The Royal Institute for Cultural Heritage (RICH) radiocarbon (14C) laboratory in Brussels, Belgiu... more The Royal Institute for Cultural Heritage (RICH) radiocarbon (14C) laboratory in Brussels, Belgium, has acquired experience for pretreating samples with 60 years of involvement in 14C dating, and the implementation of routine protocols. These procedures as applied to wood, seeds, charred materials, bones, ivory, textiles (silk, wool, cotton, linen), paper, shells, cremated bones, mortars, lead carbonates, sediments, etc. are described in detail in this paper. They are evaluated against reference materials.

Journal of Raman Spectroscopy, 2019

A recent study using the combination of optical microscopy and Raman spectroscopy revealed the pr... more A recent study using the combination of optical microscopy and Raman spectroscopy revealed the presence of bright yellow residues of lead (II) chromate associated with grinding striations on a 58,000‐year‐old grindstone excavated at Sibudu rock shelter in South Africa. Lead (II) chromate (PbCrO4) exists in nature as the rare mineral crocoite, however was available as the synthetic pigment, chrome yellow, from the 19th century. At the time of the residue analysis on the grindstone, it was not possible to determine whether the yellow residues were due to modern contamination or a result of ancient use. Careful analyses of the excavation protocol followed at Sibudu rock shelter and all implements that might possibly have been in contact with the grindstone after excavation identified yellow spray paint as a possible origin of the contamination. Here, we performed experimental grinding of the mineral crocoite on a sandstone slab, sprayed yellow paint on rhyolite and compared optical microscopy and Raman spectroscopic analysis results to the archaeological sample. The optical appearance of the archaeological residues, the absence of associated minerals of crocoite, and the presence of organic matter mixed with lead chromate demonstrate that the residues on the archaeological grindstone stem from modern contamination. This paper draws attention to contamination issues originating from excavation practices.

Journal of Raman Spectroscopy, 2018

Despite their high potential for understanding past human behaviours, the study of grindstones is... more Despite their high potential for understanding past human behaviours, the study of grindstones is limited in the literature compared with other forms of lithic tools. This paper reports the combination of optical microscopy and Raman microspectroscopy for understanding the uses of a selection of six grindstones from the post-Howiesons Poort layers at Sibudu, South Africa, dating to 58,000 years ago. Five of the specimens exhibit numerous red haematite stains which imply red ochre processing. Nevertheless, each artefact seems to have been used for a specific task. For example, the smallest grindstone was used for a combination of tasks—ochre, bone, and organic matter processing. The distinction between use residues, sediment contamination, secondary mineral formation, modern contamination, and components included in the sandstone that the grindstones are made from is discussed.

Journal of Composite Materials, 2017

Silk is a biocompatible material with remarkable mechanical properties. A variety of composite ma... more Silk is a biocompatible material with remarkable mechanical properties. A variety of composite materials using silk as a matrix or for reinforcement have been prepared for many biological applications. However, although a range of composites containing silk have been designed, the mechanical properties achieved for the regenerated silk (solubilisation + film/matrix or fibre production) remain relatively weak (strength: 30–50 MPa). In this study, by combining the high ultimate strength (up to 1 GPa) of natural silk fibres and the chemical properties of regenerated silk, we developed a composite based on silk alone. We investigated how to improve the tensile mechanical properties of silk matrices derived from Bombyx mori silkworms by film processing and by incorporating silk fibres, either natural or degummed, that is, without the sericin coating. The structure and orientation modifications of fibroin macromolecules within the matrix were monitored by Raman spectroscopy; unexpectedly ...

Journal of Field Archaeology, 2018

ABSTRACT New excavations at Border Cave use high-resolution techniques, including FT-IR, for sedi... more ABSTRACT New excavations at Border Cave use high-resolution techniques, including FT-IR, for sediment samples and thin sections of micromorphology blocks from stratigraphy. These show that sediments have different moisture regimes, both spatially and chronologically. The site preserves desiccated grass bedding in multiple layers and they, along with seeds, rhizomes, and charcoal, provide a profile of palaeo-vegetation through time. A bushveld vegetation community is implied before 100,000 years ago. The density of lithics varies considerably through time, with high frequencies occurring before 100,000 years ago where a putative MSA 1/Pietersburg Industry was recovered. The highest percentage frequencies of blades and blade fragments were found here. In Members 1 BS and 1 WA, called Early Later Stone Age by Beaumont, we recovered large flakes from multifacial cores. Local rhyolite was the most common rock used for making stone tools, but siliceous minerals were popular in the upper members.

Additional file 1. Additional figures and table.

Fibrous proteins (keratin, elastin, collagen, fibroin ...) make up to one third of the proteins o... more Fibrous proteins (keratin, elastin, collagen, fibroin ...) make up to one third of the proteins of mammals and birds. They are structural proteins with a protective and/or mechanical function. Silk appears to be the ‘simplest’ model because it mainly consists of two small amino acids residues (alanine and glycine). Some silks have comparable or superior mechanical properties compared to those of synthetic fibres and could be used in technical applications (e.g. biomedical) if the variability of their properties can be controlled. This work focuses on the structure of silks from: Bombyx mori (domestic silkworm) degummed or not, Nephila madagascariensis (wild spider, no sericin coating), GM Bombyx mori (including a gene of Nephila) a recombinant spider silk 4RepCT (Escherichia Coli). Silk is analyzed by Raman spectroscopy (and FTIR), uni-axial tensile testing, and also by the coupling of these methods. The analysis of the low wavenumbers region in Raman spectroscopy allowed the characterization of ordered regions of 2-3 microns separated by about 60 microns. This is the first evidence of the heterogeneous structure of silk. Coupling with the uni-axial tensile test shows that these ordered regions are stressed under macroscopic deformation, suggesting silk organization according to Prevorsek’s model, i.e. that the same macromolecular chain belongs to both amorphous and ordered regions. The statistical study of the mechanical properties of silkworm and spider silks shows great dispersion, but a good stability over time (decades). Genetic modification does not improve the fibres mechanical properties but a slight decrease in their variability. Various strategies have been investigated to control the variability: bacterial production, solubilization of silk and films regeneration. The role of water in silk biosynthesis, as well as the effect of various parameters (filtration, pH, drying ...) during the preparation of the films were studied. It was confirmed that the presence of protein aggregates promotes the organization in film and two types of films were prepared. The most amorphous ones have the most interesting mechanical properties, though only a few percent of those from the starting fibres. The fabrication of regenerated silk matrix composites reinforced by silk fibres increases the strength and strain to failure. These initial results are encouraging for the development of silk fibres/regenerated silk matrix composite materials.

Ochre pieces found at Middle Stone Age (MSA) and Middle Palaeolithic sites show a range of colour... more Ochre pieces found at Middle Stone Age (MSA) and Middle Palaeolithic sites show a range of colours, use-traces and applications. Ochre assemblages provide a way to explore some of the behavioural and cognitive changes that took place during the Late Pleistocene – a time of significant behavioural developments, and important cognitive implications for Homo sapiens and Neanderthals. Ochre pieces bearing engraved ‘designs’ and the preferential use of bright-red and shiny (micaceous) ochre have resulted in symbolic interpretations of the uses of ochre. But the colour of ochre can tell us more about ochre manipulation use than just colour preferences and potentially symbolic uses. Reconstructing the behavioural aspects of ochre use – such as selection preferences, collection range and source, pre-use manipulation such as heat treatment, and processing procedures – can offer valuable insight into the cognitive capabilities of the ochre users. Rose Cottage Cave and Sibudu, South Africa, contain significant and long MSA sequences dating between ~96 000 ya and 30 000 ya. They yield large ochre assemblages with a range of physical attributes and use-traces. Through experimental ochre use and heating of geological ochre samples we learned what features to look for to identify heat treatment and ochre processing techniques. With this knowledge, the physical attributes, use-traces and chemical signatures of the archaeological ochre were then examined. These multi-analytical data were combined to determine ochre selection preferences, heat treatment probabilities and ochre processing techniques used at the sites. By obtaining this valuable information from the ochre pieces we have been able to explore questions of the skill, knowledge and cognitive abilities required to perform activities involving ochre.

The Exploitation of Raw Materials in Prehistory: Sourcing, Processing and Distribution, 2017

Many Middle Stone Age (MSA) sites such as Rose Cottage and Sibudu Caves yield large quantities of... more Many Middle Stone Age (MSA) sites such as Rose Cottage and Sibudu Caves yield large quantities of ochre pieces (9000 pieces from Sibudu alone). Physico-chemical characterisation is required to add value to the prior studies of ochre use traces. This project involves a non-destructive and multi-analytical approach (including Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and X-ray fluorescence) to characterise ochre pieces. The main goal of these analyses is to establish a method to identify heated ochre pieces. This is investigated here predominantly through experimental heat treatment of geological pieces to create a database of heated ochre. Heat treatment is an indicator of advanced technological practices; this research will ultimately help to gain deeper understanding
of behaviour and cognition of people living in the MSA.