The selection and design of modern high-performance structural engineering materials is driven by optimizing combinations of mechanical properties such as strength, ductility, toughness, elasticity ...and requirements for predictable and graceful (non-catastrophic) failure in service. Highly processable bulk metallic glasses (BMGs) are a new class of engineering materials and have attracted significant technological interest. Although many BMGs exhibit high strength and show substantial fracture toughness, they lack ductility and fail in an apparently brittle manner in unconstrained loading geometries. For instance, some BMGs exhibit significant plastic deformation in compression or bending tests, but all exhibit negligible plasticity (<0.5% strain) in uniaxial tension. To overcome brittle failure in tension, BMG-matrix composites have been introduced. The inhomogeneous microstructure with isolated dendrites in a BMG matrix stabilizes the glass against the catastrophic failure associated with unlimited extension of a shear band and results in enhanced global plasticity and more graceful failure. Tensile strengths of ∼1 GPa, tensile ductility of ∼2-3 per cent, and an enhanced mode I fracture toughness of K1C 40 MPa m1/2 were reported. Building on this approach, we have developed 'designed composites' by matching fundamental mechanical and microstructural length scales. Here, we report titanium-zirconium-based BMG composites with room-temperature tensile ductility exceeding 10 per cent, yield strengths of 1.2-1.5 GPa, K1C up to ∼170 MPa m1/2, and fracture energies for crack propagation as high as G1C 340 kJ m-2. The K1C and G1C values equal or surpass those achievable in the toughest titanium or steel alloys, placing BMG composites among the toughest known materials.
The mechanical properties of bulk metallic glasses (BMGs) and their composites have been under intense investigation for many years, owing to their unique combination of high strength and elastic ...limit. However, because of their highly localized deformation mechanism, BMGs are typically considered to be brittle materials and are not suitable for structural applications. Recently, highly-toughened BMG composites have been created in a Zr-Ti-based system with mechanical properties comparable with high-performance crystalline alloys. In this work, we present a series of low-density, Ti-based BMG composites with combinations of high strength, tensile ductility, and excellent fracture toughness.
This paper aims to identify and quantify the main potential environmental impacts of the sugarcane bagasse electricity generation in Brazil. To do so, it was employed the Life Cycle Assessment (LCA) ...technique based on primary and secondary data from three previous studies encompassing electricity generation, transmission and distribution processes. It was identified that the main impact potentials of this type of electricity generation in Brazil that should be addressed by decision-makers are the photochemical ozone, the human toxicity via soil and the nutrient enrichment ones, which are caused mainly by the sugarcane straw burning prior harvesting and the chemical application. In addition, it was found that non-renewable resources, renewable resources and energy consumption are also important issues that should be addressed mostly in the process of electricity transmission.
PBX1 is a highly conserved atypical homeodomain transcription factor (TF) belonging to the TALE (three amino acid loop extension) family. Dimerized with other TALE proteins, it can interact with ...numerous partners and reach dozens of regulating sequences, suggesting its role as a pioneer factor. PBX1 is expressed throughout the embryonic stages (as early as the blastula stage) in vertebrates. In human, PBX1 germline variations are linked to syndromic renal anomalies (CAKUTHED). In this review, we summarized available data on PBX1 functions, PBX1‐deficient animal models, and PBX1 germline variations in humans. Two types of genetic alterations were identified in PBX1 gene. PBX1 missense variations generate a severe phenotype including lung hypoplasia, cardiac malformations, and sexual development defects (DSDs). Conversely, truncating variants generate milder phenotypes (mainly cryptorchidism and deafness). We suggest that defects in PBX1 interactions with various partners, including proteins from the HOX (HOXA7, HOXA10, etc.), WNT (WNT9B, WNT3), and Polycomb (BMI1, EED) families are responsible for abnormal proliferation and differentiation of the embryonic mesenchyme. These alterations could explain most of the defects observed in humans. However, some phenotype variability (especially DSDs) remains poorly understood. Further studies are needed to explore the TALE family in greater depth.
► A thin film composite membrane structure employing a polyamide selective layer anchored to a nanostructured support. ► The support consists of an electrospun nanofiber nonwoven and an optional ...polyester nonwoven support. ► Electrospun nanofibers exhibit high porosity and low tortuosity. ► A traditional interfacial polymerization approach was used to form the selective polyamide layer. ► These new membranes exhibted higher water flux and lower salt flux when compared to a commercial forward osmosis membrane.
Engineered osmosis (EO) is a membrane based separation technology with applications to sustainable energy, resource recovery, and water production. Still emerging, EO utilizes energy stored as chemical potential (osmotic pressure) to generate power or purify water, but the lack of membranes with suitable water flux, solute rejection, mechanical strength, and chemical stability has limited EO development. In this study, we attempt to address low water flux by proposing a novel thin film composite membrane for EO. This TFC membrane comprises an electrospun polymeric nanofiber support layer and a polyamide skin layer formed by
in situ polymerization. The best nanofiber supported-polyamide composite membranes exhibited two to five times higher flux with up to 100 times lower salt flux than a standard commercial forward osmosis membrane. These results suggest that electrospun nanofiber supported polyamide composite membranes may enable applications like forward osmosis where internal concentration polarization is the performance-limiting factor. More research is needed to establish the applicability of this new membrane design for engineered osmosis applications involving harsh chemical environments and elevated mechanical pressures.
Herein we report on the formation and characterization of pure polyamide thin film composite (TFC) and zeolite-polyamide thin film nanocomposite (TFN) reverse osmosis (RO) membranes. Four different ...physical-chemical post-treatment combinations were applied after the interfacial polymerization reaction to change the molecular structure of polyamide and zeolite-polyamide thin films. Both TFC and TFN hand-cast membranes were more permeable, hydrophilic, and rough than a commercial seawater RO membrane. Salt rejection by TFN membranes was consistently below that of hand-cast TFC membranes; however, two TFN membranes exhibited 32 g/L NaCl rejections above 99.4%, which was better than the commercial membrane under the test conditions employed. The nearly defect-free TFN films that produced such high rejections were achieved only with wet curing, regardless of other post-treatments. Polyamide films formed in the presence of zeolite nanoparticles were less cross-linked than similarly cast pure polyamide films. At the very low nanoparticle loadings evaluated, differences between pure polyamide and zeolite-polyamide membrane water and salt permeability correlated weakly with extent of cross-linking of the polyamide film, which suggests that defects and molecular-sieving largely govern transport through zeolite-polyamide thin film nanocomposite membranes.
Awareness of, and debate about, harassment, assault, bullying and intimidation (HABI) in archaeology has grown in recent years, but the issue remains under-researched. Here, the authors present the ...first Europe-wide survey to evaluate HABI in archaeological environments, from field to laboratory and classroom. The survey covers 18 forms of HABI, collecting more than 1000 responses from archaeologists of 49 nationalities. A total of 82 per cent of respondents report at least one HABI experience. The authors conclude that HABI is endemic in European archaeology, being experienced by all genders and ages, in multiple settings and countries. Documenting these behaviours is a critical first step to eradicating them and to achieving equity and safety in the discipline.
Scythians are known from written sources as horse-riding nomadic peoples who dominated the Eurasian steppe throughout the Iron Age. However, their origins and the exact nature of their social ...organization remain debated. Three hypotheses prevail regarding their origins that can be summarized as a “western origin”, an “eastern origin” and a “multi-regional origin”. In this work, we first aimed to address the question of the familial and social organization of some Scythian groups (Scytho-Siberians) by testing genetic kinship and, second, to add new elements on their origins through phylogeographical analyses. Twenty-eight Scythian individuals from 5 archeological sites in the Tuva Republic (Russia) were analyzed using autosomal Short Tandem Repeats (STR), Y-STR and Y-SNP typing as well as whole mitochondrial (mtDNA) genome sequencing. Familial relationships were assessed using the Likelihood Ratio (LR) method. Thirteen of the 28 individuals tested were linked by first-degree relationships. When related, the individuals were buried together, except for one adult woman, buried separately from her mother and young sister. Y-chromosome analysis revealed a burial pattern linked to paternal lineages, with men bearing closely related Y-haplotypes buried on the same sites. Inversely, various mtDNA lineages can be found on each site. Y-chromosomal and mtDNA haplogroups were almost equally distributed between Western and Eastern Eurasian haplogroups. These results suggest that Siberian Scythians were organized in patrilocal and patrilineal societies with burial practices linked to both kinship and paternal lineages. It also appears that the group analyzed shared a greater genetic link with Asian populations than Western Scythians did.
Colorimetric sensors are widely used because of their inherent advantages including accuracy, rapid response, ease-of-use, and low costs; however, they usually lack reusability, which precludes the ...continuous use of a single sensor. We have developed a threshold-responsive colorimetric system that enables repeated analyte measurements by a single colorimetric sensor. The threshold responsive algorithm automatically adjusts the sensor exposure time to the analyte and measurement frequency according to the sensor response. The system registers the colorimetric sensor signal change rate, prevents the colorimetric sensor from reaching saturation, and allows the sensor to fully regenerate before the next measurement is started. The system also addresses issues common to colorimetric sensors, including the response time and range of detection. We demonstrate the benefits and feasibility of this novel system, using colorimetric sensors for ammonia and carbon dioxide gases for continuous monitoring of up to (at least) 60 detection cycles without signs of analytical performance degradation of the sensors.
Women scientists tend to disappear from history: their contributions are often minimised, forgotten or erased. In the late 1980s and the early 1990s, several archaeologists based in Norway and the ...United States worked on rehabilitating these women, and more generally people from different minority groups, and on bringing their research to light. From the late 1970s to the late 1990s, these studies documented the gendered division of labour, salary inequalities, differences in promotion, degrees, fellowships, and publications. From the late 1990s onwards, research focused on new themes such as gender and sexual violence, menstruation, pregnancy and maternity in the field, as well as discriminations faced by racialised, homosexual, bisexual, transgender and/or disabled people. French archaeologists lagged behind on these issues until the 2010s. Since 2017, the collective Paye ta Truelle has been bringing feminist critique in the field and about the field in French-speaking research. This article shows that feminist thought, by questioning society, has also contributed to questioning research in archaeology and history, whether in Norway, the United States or France.
PDF
