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1.
Nature ; 581(7808): 299-302, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32433609

RESUMEN

The Middle to Upper Palaeolithic transition in Europe witnessed the replacement and partial absorption of local Neanderthal populations by Homo sapiens populations of African origin1. However, this process probably varied across regions and its details remain largely unknown. In particular, the duration of chronological overlap between the two groups is much debated, as are the implications of this overlap for the nature of the biological and cultural interactions between Neanderthals and H. sapiens. Here we report the discovery and direct dating of human remains found in association with Initial Upper Palaeolithic artefacts2, from excavations at Bacho Kiro Cave (Bulgaria). Morphological analysis of a tooth and mitochondrial DNA from several hominin bone fragments, identified through proteomic screening, assign these finds to H. sapiens and link the expansion of Initial Upper Palaeolithic technologies with the spread of H. sapiens into the mid-latitudes of Eurasia before 45 thousand years ago3. The excavations yielded a wealth of bone artefacts, including pendants manufactured from cave bear teeth that are reminiscent of those later produced by the last Neanderthals of western Europe4-6. These finds are consistent with models based on the arrival of multiple waves of H. sapiens into Europe coming into contact with declining Neanderthal populations7,8.


Asunto(s)
Fósiles , Migración Humana/historia , Animales , Asia , Huesos/metabolismo , Bulgaria , Cuevas , ADN Antiguo/aislamiento & purificación , ADN Mitocondrial/genética , ADN Mitocondrial/aislamiento & purificación , Europa (Continente) , Historia Antigua , Humanos , Hombre de Neandertal/genética , Filogenia , Comportamiento del Uso de la Herramienta , Diente/anatomía & histología , Diente/metabolismo
2.
J Hum Evol ; 167: 103198, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35533625

RESUMEN

The expansion of Homo sapiens and our interaction with local environments, including the replacement or absorption of local populations, is a key component in understanding the evolution of our species. Of special interest are artifacts made from hard animal tissues from layers at Bacho Kiro Cave (Bulgaria) that have been attributed to the Initial Upper Paleolithic. The Initial Upper Paleolithic is characterized by Levallois-like blade technologies that can co-occur with bone tools and ornaments and likely represents the dispersal of H. sapiens into several regions throughout Eurasia starting by 45 ka or possibly earlier. Osseous artifacts from the Initial Upper Paleolithic are important components of this record and have the potential to contribute to our understanding of group interactions and population movements. Here, we present a zooarchaeological, technological, and functional analysis of the diverse and sizable osseous artifact collection from Bacho Kiro Cave. Animal raw material sources are consistent with taxa found within the faunal assemblage including cervids, large bovids, and cave bears. A variety of bone tool morphologies, both formal and informal, indicate a diverse technological approach for conducting various on-site activities, many of which were focused on the processing of animal skins, likely for cold weather clothing. Technological flexibility is also evident in the manufacture of personal ornaments, which were made primarily from carnivore teeth, especially cave bear, though herbivore teeth and small beads are also represented. The osseous artifacts from Bacho Kiro Cave provide a series of insights into the bone technology and indirectly on the social aspects of these humans in southeast Europe, and when placed within the broader Initial Upper Paleolithic context, both regional and shared behaviors are evidently indicating widespread innovation and complexity. This is especially significant given the location and chronology of the site in the context of H. sapiens dispersals.


Asunto(s)
Arqueología , Hominidae , Animales , Bulgaria , Cuevas , Fósiles , Tecnología
3.
J Am Chem Soc ; 143(22): 8249-8254, 2021 06 09.
Artículo en Inglés | MEDLINE | ID: mdl-34043343

RESUMEN

Physisorption using gas or vapor probe molecules is the most common characterization technique for porous materials. The method provides textural information on the adsorbent as well as the affinity for a specific adsorbate, typically through equilibrium pressure measurements. Here, we demonstrate how low-field NMR can be used to measure full adsorption isotherms, and how by selectively measuring 1H spins of the adsorbed probe molecules, rather than those in the vapor phase, this "NMR-relaxorption" technique provides insights about local dynamics beyond what can be learned from physisorption alone. The potential of this double-barreled approach was illustrated for a set of microporous metal-organic frameworks (MOFs). For methanol adsorption in ZIF-8, the method identifies multiple guest molecules populations assigned to MeOH clusters in the pore center, MeOH bound at cage windows and to MeOH adsorption on defect sites. For UiO-66(Zr), the sequential pore filling is demonstrated and accurate pore topologies are directly obtained, and for MIL-53(Al), structural phase transitions are accurately detected and linked with two populations of dimeric chemical species localized to specific positions in the framework.

4.
Chemistry ; 26(47): 10841-10848, 2020 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-32476184

RESUMEN

Energy-efficient indoors temperature and humidity control can be realised by using the reversible adsorption and desorption of water in porous materials. Stable microporous aluminium-based metal-organic frameworks (MOFs) present promising water sorption properties for this goal. The development of synthesis routes that make use of available and affordable building blocks and avoid the use of organic solvents is crucial to advance this field. In this work, two scalable synthesis routes under mild reaction conditions were developed for aluminium-based MOFs: (1) in aqueous solutions using a continuous-flow reactor and (2) through the vapour-assisted conversion of solid precursors. Fumaric acid, its methylated analogue mesaconic acid, as well as mixtures of the two were used as linkers to obtain polymorph materials with tuneable water sorption properties. The synthesis conditions determine the crystal structure and either the MIL-53 or MIL-68 type structure with square-grid or kagome-grid topology, respectively, is formed. Fine-tuning resulted in new MOF materials thus far inaccessible through conventional synthesis routes. Furthermore, by varying the linker ratio, the water sorption properties can be continuously adjusted while retaining the sigmoidal isotherm shape advantageous for heat transformation and room climatisation applications.

5.
Molecules ; 26(1)2020 Dec 22.
Artículo en Inglés | MEDLINE | ID: mdl-33375128

RESUMEN

The demand for more ecological, highly engineered hydrogel beads is driven by a multitude of applications such as enzyme immobilization, tissue engineering and superabsorbent materials. Despite great interest in hydrogel fabrication and utilization, the interaction of hydrogels with water is not fully understood. In this work, NMR relaxometry experiments were performed to study bead-water interactions, by probing the changes in bead morphology and surface energy resulting from the incorporation of carboxymethyl cellulose (CMC) into a cellulose matrix. The results show that CMC improves the swelling capacity of the beads, from 1.99 to 17.49, for pure cellulose beads and beads prepared with 30% CMC, respectively. Changes in water mobility and interaction energy were evaluated by NMR relaxometry. Our findings indicate a 2-fold effect arising from the CMC incorporation: bead/water interactions were enhanced by the addition of CMC, with minor additions having a greater effect on the surface energy parameter. At the same time, bead swelling was recorded, leading to a reduction in surface-bound water, enhancing water mobility inside the hydrogels. These findings suggest that topochemical engineering by adjusting the carboxymethyl cellulose content allows the tuning of water mobility and porosity in hybrid beads and potentially opens up new areas of application for this biomaterial.


Asunto(s)
Carboximetilcelulosa de Sodio/química , Celulosa/química , Ingeniería Química , Espectroscopía de Resonancia Magnética , Microesferas , Algoritmos , Ingeniería Química/métodos , Portadores de Fármacos/química , Hidrogeles/química , Espectroscopía de Resonancia Magnética/métodos , Modelos Químicos
6.
Molecules ; 24(3)2019 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-30736295

RESUMEN

Three new complexes [Mo(η³-C3H5)Br(CO)2{iPrN=C(R)C5H4N}], where R = H (IMP = N-isopropyl 2-iminomethylpyridine), Me, and Ph, were synthesized and characterized, and were fluxional in solution. The most interesting feature was the presence, in the crystal structure of the IMP derivative, of the two main isomers (allyl and carbonyls exo), namely the equatorial isomer with the Br trans to the allyl and the equatorial with the Br trans to one carbonyl, the position trans to the allyl being occupied by the imine nitrogen atom. For the R = Me complex, the less common axial isomer was observed in the crystal. These complexes were immobilized in MCM-41 (MCM), following functionalization of the diimine ligands with Si(OEt)3, in order to study the catalytic activity in olefin epoxidation of similar complexes as homogeneous and heterogeneous catalysts. FTIR, 13C- and 29Si-NMR, elemental analysis, and adsorption isotherms showed that the complexes were covalently bound to the MCM walls. The epoxidation activity was very good in both catalysts for the cis-cyclooctene and cis-hex-3-en-1-ol, but modest for the other substrates tested, and no relevant differences were found between the complexes and the Mo-containing materials as catalysts.


Asunto(s)
Iminas/química , Molibdeno/química , Catálisis , Técnicas de Química Sintética , Compuestos Epoxi/química , Iminas/síntesis química , Ligandos , Espectroscopía de Resonancia Magnética , Conformación Molecular , Estructura Molecular , Difracción de Rayos X
7.
Angew Chem Int Ed Engl ; 58(51): 18471-18475, 2019 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-31593354

RESUMEN

Zeolitic imidazolate frameworks (ZIFs) are a sub-class of metal-organic frameworks (MOFs). Although generally stable, ZIFs can undergo post-synthetic linker exchange (PSLE) in solution under mild conditions. Herein, we present a novel, solvent-free approach to post-synthetic linker exchange through exposure to linker vapor.

8.
Sci Rep ; 14(1): 20084, 2024 08 29.
Artículo en Inglés | MEDLINE | ID: mdl-39209937

RESUMEN

Information about the use of stone tools in the past is encoded in the wear patterns left on their surface; however, post-depositional processes can modify and obstruct these traces. One aim in the field of lithic functional analysis is to develop methods to detect and quantify these traces on stone tools. The occlusal fingerprint analysis (OFA) is a well-established method in dental wear studies to virtually simulate dental occlusal (contact between teeth) stroke movements and thus locate and quantify the sequential contact between opposing tooth crowns. Reaching across disciplines, we conducted controlled experiments to test the applicability of the OFA method on stone tools to address the challenge of use-wear quantification and localisation, and therefore the identification of post-depositional wear. Our findings reveal a clear overlap between zones of experimentally produced use-wear and OFA-calculated contact areas. We demonstrate OFA as a potential method to generate models of multiscale use-wear that can be used as references on experimental tools to identify post-depositional surface modifications on stone tool artefacts.


Asunto(s)
Desgaste de los Dientes , Humanos , Oclusión Dental , Corona del Diente
9.
Chem Mater ; 36(11): 5378-5387, 2024 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-38883436

RESUMEN

The effects of impurities on reaction precursors for metal-organic framework (MOF) synthesis have not been studied in extensive detail. The impact of these impurities can be an important factor while considering scale-up of these materials. In this work, we study the apparently positive impact of the presence of manganese ions for the synthesis of a Co-based MOF, Massey University Framework-16 (MUF-16). The presence of a trace amount of manganese in the reaction mixture led to consistently high CO2 uptake across multiple batches. Characterization including X-ray diffraction, scanning electron microscopy, Fourier transform infrared-attenuated total reflectance, ultraviolet-visible spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure spectroscopy led us to hypothesize that the differences in CO2 adsorption among materials with differing synthesis routes arise from variations in the local environment around the cobalt metal center. Aided by density functional theory calculations, we speculate that manganese ions get inserted into the structure during crystallization and act as catalysts for ligand substitution, improving the possibility for octahedral coordination of cobalt with the ligand, thus leading to Co-based pristine structures with higher CO2 uptakes.

10.
PLoS One ; 19(9): e0307435, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39231140

RESUMEN

The dispersal of Homo sapiens across Eurasia during MIS 3 in the Late Pleistocene is marked by technological shifts and other behavioral changes, known in the archaeological record under the term of Initial Upper Paleolithic (IUP). Bacho Kiro Cave in north Bulgaria, re-excavated by us from 2015 to 2021, is one of the reference sites for this phenomenon. The newly excavated lithic assemblages dated by radiocarbon between 45,040 and 43,280 cal BP and attributed to Homo sapiens encompass more than two thousand lithic artifacts. The lithics, primarily from Layer N1-I, exist amid diverse fauna remains, human fossils, pierced animal teeth pendants, and sediment with high organic content. This article focuses on the technological aspects of the IUP lithics, covering raw material origin and use-life, blank production, on-site knapping activities, re-flaking of lithic implements, and the state of retouched lithic components. We apply petrography for the identification of silicites and other used stones. We employ chaîne opératoire and reduction sequence approaches to profile the lithics techno-typologically and explore the lithic economy, particularly blade production methods, knapping techniques, and artifact curation. Raw material analysis reveals Lower Cretaceous flints from Ludogorie and Upper Cretaceous flints from the Danube region, up to 190 km and 130 km, respectively, from Bacho Kiro Cave, indicating long-distance mobility and finished products transport. Imported lithic implements, were a result of unidirectional and bidirectional non-Levallois laminar technology, likely of volumetric concept. Systematic on-anvil techniques (bipolar knapping) and tool segmentation indicate re-flaking and reshaping of lithic implements, reflecting on-site curation and multifaceted lithic economy. A limited comparison with other IUP sites reveals certain shared features and also regional variations. Bacho Kiro Cave significantly contributes to understanding the technological and behavioral evolution of early Homo sapiens in western Eurasia.


Asunto(s)
Arqueología , Cuevas , Fósiles , Humanos , Bulgaria , Animales , Tecnología/historia , Sedimentos Geológicos/análisis , Artefactos
11.
PLoS One ; 18(11): e0295081, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38032889

RESUMEN

In stone tool studies, the analysis of different technological and typological features is known to provide distinct but interrelated information on the design and use of artefacts. The selection of these features can potentially influence the understanding and reconstruction of past human technological behaviour across time. One feature frequently part of a standard lithic analysis is the measurement of edge angles. The angle of an edge, unmodified or shaped by retouch and an integral part of the overall tool design, is certainly a parameter that influences the interpretation of an artefact. The acuteness of an edge angle is often linked to aspects such as cutting, carving, or scraping efficiency and durability and thus, tool performance. Knowing the actual edge angle of a stone tool can therefore have important implications for its interpretation. In the case of edge angle analyses, manual measuring techniques have been established for many years in lithic studies. Here, we introduce a new method for accurate and precise edge angle measurements based on 3D data (hereafter 3D-EdgeAngle). 3D-EdgeAngle consists of a script-based, semi-automated edge angle measuring method applicable to 3D models. Unlike other methods, 3D-EdgeAngle illustrates an objective way of measuring the edge angle at cross sections along the entire tool edge in defined steps and, moreover, allows measurements at different distances perpendicular to the edge by controlling three involved parameters. Thus, with this method, the edge angle can be measured at any point in a high resolution and scale of analysis. Compared to measurements taken manually, with this method random and systematic errors can be reduced significantly. Additionally, all data are reproducible and statistically evaluable. We introduce 3D-EdgeAngle as a standard method to calculate edge angles with a highly accurate and systematic approach. With this method, we aim to improve the process of studying lithics and thus to increase the understanding of past human tool design.

12.
Sci Rep ; 12(1): 14152, 2022 08 19.
Artículo en Inglés | MEDLINE | ID: mdl-35986053

RESUMEN

The Aurignacian is one of the first cultural-technological traditions commonly associated with the expansion of Homo sapiens in Europe. Early Homo sapiens demographics across the continent are therefore typically inferred using the distribution of Aurignacian assemblages. Western Romania has been used as a tie-point to connect the well-researched lithic assemblages from the eastern Mediterranean and Western Europe through its early Homo sapiens fossils. However, Romania's archeological record remains underexplored thereby hindering our ability to directly connect better understood regions through time and space. Here we report on excavations from the open-air Middle/Upper Paleolithic site of Românești-Dumbravița I in southwestern Romania. Three stratified Paleolithic assemblages were extensively excavated within a 1-m-thick eolian-deposited sequence. Spatial, geochemical, raw material, techno-typological, and use-wear analysis of the site reveal patterns of artifact configuration, resource exploitation, fire history, knapping objectives, and functionality. Taken together, Românești-Dumbravița I is the first well-contextualized archeological site in close spatiotemporal proximity to many early, well-preserved human fossils and in East-Central Europe.


Asunto(s)
Arqueología , Fósiles , Europa (Continente) , Humanos , Análisis Espacial , Tecnología
13.
iScience ; 25(11): 105315, 2022 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-36304114

RESUMEN

The ability of humans to mediate environmental variation through tool use is likely the key to our success. However, our current knowledge of early cultural evolution derives almost exclusively from studies of stone tools and fossil bones found in the archaeological record. Tools made of plants are intrinsically perishable, and as such are almost entirely absent in the early record of human material culture. Modern human societies as well as nonhuman primate species use plant materials for tools far more often than stone, suggesting that current archaeological data are missing a substantial component of ancient technology. Here, we develop methods that quantify internal and external damage pattern in percussive wooden tools of living primates. Our work shows that the inflicted damage is irreversible, potentially persisting throughout fossilization processes. This research presents opportunities to investigate organic artifacts, a significant and highly neglected aspect of technological evolution within the Primate order.

14.
Adv Mater ; 34(27): e2201502, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35603497

RESUMEN

Porosity and surface area analysis play a prominent role in modern materials science. At the heart of this sits the Brunauer-Emmett-Teller (BET) theory, which has been a remarkably successful contribution to the field of materials science. The BET method was developed in the 1930s for open surfaces but is now the most widely used metric for the estimation of surface areas of micro- and mesoporous materials. Despite its widespread use, the calculation of BET surface areas causes a spread in reported areas, resulting in reproducibility problems in both academia and industry. To prove this, for this analysis, 18 already-measured raw adsorption isotherms were provided to sixty-one labs, who were asked to calculate the corresponding BET areas. This round-robin exercise resulted in a wide range of values. Here, the reproducibility of BET area determination from identical isotherms is demonstrated to be a largely ignored issue, raising critical concerns over the reliability of reported BET areas. To solve this major issue, a new computational approach to accurately and systematically determine the BET area of nanoporous materials is developed. The software, called "BET surface identification" (BETSI), expands on the well-known Rouquerol criteria and makes an unambiguous BET area assignment possible.


Asunto(s)
Reproducibilidad de los Resultados , Adsorción , Porosidad
15.
Adv Mater ; 33(17): e2006993, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33733524

RESUMEN

Thin films of crystalline and porous metal-organic frameworks (MOFs) have great potential in membranes, sensors, and microelectronic chips. While the morphology and crystallinity of MOF films can be evaluated using widely available techniques, characterizing their pore size, pore volume, and specific surface area is challenging due to the low amount of material and substrate effects. Positron annihilation lifetime spectroscopy (PALS) is introduced as a powerful method to obtain pore size information and depth profiling in MOF films. The complementarity of this approach to established physisorption-based methods such as quartz crystal microbalance (QCM) gravimetry, ellipsometric porosimetry (EP), and Kr physisorption (KrP) is illustrated. This comprehensive discussion on MOF thin film porosimetry is supported by experimental data for thin films of ZIF-8.

16.
PLoS One ; 16(2): e0245700, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33539405

RESUMEN

The Armenian highlands encompasses rugged and environmentally diverse landscapes and is characterized by a mosaic of distinct ecological niches and large temperature gradients. Strong seasonal fluctuations in resource availability along topographic gradients likely prompted Pleistocene hominin groups to adapt by adjusting their mobility strategies. However, the role that elevated landscapes played in hunter-gatherer settlement systems during the Late Pleistocene (Middle Palaeolithic [MP]) remains poorly understood. At 1640 m above sea level, the MP site of Kalavan 2 (Armenia) is ideally positioned for testing hypotheses involving elevation-dependent seasonal mobility and subsistence strategies. Renewed excavations at Kalavan 2 exposed three main occupation horizons and ten additional low densities lithic and faunal assemblages. The results provide a new chronological, stratigraphical, and paleoenvironmental framework for hominin behaviors between ca. 60 to 45 ka. The evidence presented suggests that the stratified occupations at Kalavan 2 locale were repeated ephemerally most likely related to hunting in a high-elevation within the mountainous steppe landscape.


Asunto(s)
Altitud , Arqueología/métodos , Hominidae , Ocupaciones/historia , Estaciones del Año , Migración Animal , Animales , Armenia , Artefactos , Fósiles , Historia Antigua , Humanos , Tecnología
17.
Sci Rep ; 9(1): 6313, 2019 04 19.
Artículo en Inglés | MEDLINE | ID: mdl-31004088

RESUMEN

Many archeologists are skeptical about the capabilities of use-wear analysis to infer on the function of archeological tools, mainly because the method is seen as subjective, not standardized and not reproducible. Quantitative methods in particular have been developed and applied to address these issues. However, the importance of equipment, acquisition and analysis settings remains underestimated. One of those settings, the numerical aperture of the objective, has the potential to be one of the major factors leading to reproducibility issues. Here, experimental flint and quartzite tools were imaged using laser-scanning confocal microscopy with two objectives having the same magnification but different numerical apertures. The results demonstrate that 3D surface texture ISO 25178 parameters differ significantly when the same surface is measured with objectives having different numerical apertures. It is, however, unknown whether this property would blur or mask information related to use of the tools. Other acquisition and analyses settings are also discussed. We argue that to move use-wear analysis toward standardization, repeatability and reproducibility, the first step is to report all acquisition and analysis settings. This will allow the reproduction of use-wear studies, as well as tracing the differences between studies to given settings.

18.
Psicol. reflex. crit ; 27(4): 615-624, Oct-Dec/2014. tab, graf
Artículo en Portugués | LILACS, Index Psi Revistas Técnico-Científicas | ID: lil-728837

RESUMEN

Este trabalho teve como objetivo analisar as propriedades psicométricas do Questionário de Apoio às Necessidades Psicológicas Básicas (QANPB) com estudantes portugueses. A amostra foi constituída por 445 estudantes do sexo masculino e feminino, com idades compreendidas entre os 12 e os 16 anos. Inicialmente, a escala foi traduzida para o português, para posteriormente se realizar uma análise das propriedades psicométricas. Os resultados comprovaram que o QANPB se apresentava como um instrumento com evidências de validade (fatorial e nomológica) e confiabilidade, que permite analisar a percepção dos alunos sobre o apoio do professor à autonomia, competência e relações sociais nas aulas de Educação Física. (AU)


The purpose of this study was to analyze the psychometric properties of the Basic Psychological Needs Questionnaire (BPNQ) with Portuguese students. The sample was composed of 445 male and female students, ranging in age from 12 to 16 years. Initially, the scale was translated into Portuguese, and later, an analysis of the psychometric properties was done. Results emphasized that the BPNQ is a valid (factorial and nomological) and reliable instrument to measure students' perception of autonomy, competence and relatedness support in Physical Education classes. (AU)


Asunto(s)
Humanos , Masculino , Femenino , Adolescente , Estudiantes/psicología , Traducción , Reproducibilidad de los Resultados , Docentes , Relaciones Interpersonales , Educación y Entrenamiento Físico , Portugal , Psicometría , Autonomía Personal , Habilidades Sociales
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