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Concept: Bronze

195

Noroviruses (family Caliciviridae) are the primary cause of viral gastroenteritis worldwide. The virus is highly infectious and touching contaminated surfaces can contribute to infection spread. Although the virus was identified over 40 years ago the lack of methods to assess infectivity has hampered the study of the human pathogen. Recently the murine virus, MNV-1, has successfully been used as a close surrogate. Copper alloys have previously been shown to be effective antimicrobial surfaces against a range of bacteria and fungi. We now report rapid inactivation of murine norovirus on alloys, containing over 60% copper, at room temperature but no reduction of infectivity on stainless steel dry surfaces in simulated wet fomite and dry touch contamination. The rate of inactivation was initially very rapid and proportional to copper content of alloy tested. Viral inactivation was not as rapid on brass as previously observed for bacteria but copper-nickel alloy was very effective. The use of chelators and quenchers of reactive oxygen species (ROS) determined that Cu(II) and especially Cu(I) ions are still the primary effectors of toxicity but quenching superoxide and hydroxyl radicals did not confer protection. This suggests Fenton generation of ROS is not important for the inactivation mechanism. One of the targets of copper toxicity was the viral genome and a reduced copy number of the gene for a viral encoded protein, VPg (viral-protein-genome-linked), which is essential for infectivity, was observed following contact with copper and brass dry surfaces. The use of antimicrobial surfaces containing copper in high risk closed environments such as cruise ships and care facilities could help to reduce the spread of this highly infectious and costly pathogen.

Concepts: Virus, Zinc, Copper, Bronze, Steel, Gastroenteritis, Norovirus, Brass

101

To assess the ability of copper alloy surfaces to mitigate the bacterial burden associated with commonly touched surfaces in conjunction with daily and terminal cleaning in rural hospital settings.

Concepts: Bronze, Brass

30

Mobility is one of the most important processes shaping spatiotemporal patterns of variation in genetic, morphological, and cultural traits. However, current approaches for inferring past migration episodes in the fields of archaeology and population genetics lack either temporal resolution or formal quantification of the underlying mobility, are poorly suited to spatially and temporally sparsely sampled data, and permit only limited systematic comparison between different time periods or geographic regions. Here we present an estimator of past mobility that addresses these issues by explicitly linking trait differentiation in space and time. We demonstrate the efficacy of this estimator using spatiotemporally explicit simulations and apply it to a large set of ancient genomic data from Western Eurasia. We identify a sequence of changes in human mobility from the Late Pleistocene to the Iron Age. We find that mobility among European Holocene farmers was significantly higher than among European hunter-gatherers both pre- and postdating the Last Glacial Maximum. We also infer that this Holocene rise in mobility occurred in at least three distinct stages: the first centering on the well-known population expansion at the beginning of the Neolithic, and the second and third centering on the beginning of the Bronze Age and the late Iron Age, respectively. These findings suggest a strong link between technological change and human mobility in Holocene Western Eurasia and demonstrate the utility of this framework for exploring changes in mobility through space and time.

Concepts: Genetics, Europe, Bronze, Neolithic, Pleistocene, Bronze Age, Synoptic table of the principal old world prehistoric cultures, Iron Age

28

Fifty-nine dental non-metric traits were scored using Arizona State University Dental Anthropology System on a sample of teeth from 350 human skeletons excavated at three sites in the lower middle Euphrates valley. The dataset was divided into six chronological subsets: Early Bronze Age, Middle Bronze Age, Early Iron Age with Neo-Assyrian period, Classical/Late Antiquity, Early Islamic (Umayyad and Abbasid) period and Modern period. The matrix of Mean Measure of Divergence values exhibited temporal homogeneity of the sample with only dental non-metric trait scores in the Modern subset differing significantly from most other subsets. Such a result suggests that no major gene flow occurred in the middle Euphrates valley between the 3rd millennium BCE and the early 2nd millennium CE. Only after the Mongolian invasion and large depopulation of northern Mesopotamia in the 13th century CE a major population change occurred when the area was taken over in the 17th century by Bedouin tribes from the Arabian Peninsula.

Concepts: Bronze, Iraq, Bronze Age, Synoptic table of the principal old world prehistoric cultures, Mesopotamia, Iron Age, Tumulus, Ancient Near East

28

Although in many cases Pb isotopic analysis can be relied on for provenance determination of ancient bronzes, sometimes the use of “non-traditional” isotopic systems, such as those of Cu and Sn, is required. The work reported on in this paper aimed at revising the methodology for Cu and Sn isotope ratio measurements in archaeological bronzes via optimization of the analytical procedures in terms of sample pre-treatment, measurement protocol, precision, and analytical uncertainty. For Cu isotopic analysis, both Zn and Ni were investigated for their merit as internal standard (IS) relied on for mass bias correction. The use of Ni as IS seems to be the most robust approach as Ni is less prone to contamination, has a lower abundance in bronzes and an ionization potential similar to that of Cu, and provides slightly better reproducibility values when applied to NIST SRM 976 Cu isotopic reference material. The possibility of carrying out direct isotopic analysis without prior Cu isolation (with AG-MP-1 anion exchange resin) was investigated by analysis of CRM IARM 91D bronze reference material, synthetic solutions, and archaeological bronzes. Both procedures (Cu isolation/no Cu isolation) provide similar δ (65)Cu results with similar uncertainty budgets in all cases (±0.02-0.04 per mil in delta units, k = 2, n = 4). Direct isotopic analysis of Cu therefore seems feasible, without evidence of spectral interference or matrix-induced effect on the extent of mass bias. For Sn, a separation protocol relying on TRU-Spec anion exchange resin was optimized, providing a recovery close to 100 % without on-column fractionation. Cu was recovered quantitatively together with the bronze matrix with this isolation protocol. Isotopic analysis of this Cu fraction provides δ (65)Cu results similar to those obtained upon isolation using AG-MP-1 resin. This means that Cu and Sn isotopic analysis of bronze alloys can therefore be carried out after a single chromatographic separation using TRU-Spec resin. Tin isotopic analysis was performed relying on Sb as an internal standard used for mass bias correction. The reproducibility over a period of 1 month (n = 42) for the mass bias-corrected Sn isotope ratios is in the range of 0.06-0.16 per mil (2 s), for all the ratios monitored.

Concepts: Scientific method, Zinc, Copper, Analytical chemistry, Isotope, Bronze, Tin, Bronze Age

22

Athletic centers have been locations for the transmission of community-acquired infections. This study assessed the capacity of copper alloys to reduce the bacterial burden associated with high-touch athletic center equipment. Copper alloy weights and grips were rotated with rubber coated and stainless steel controls in an undergraduate college athletic center over a 16-month period. The athletic center is used by college athletic teams, student body, and local community.

Concepts: Iron, Zinc, Metallurgy, Alloy, Bronze, Steel, Brass, Corrosion

18

The evolution of new and reemerging historic virulent strains of respiratory viruses from animal reservoirs is a significant threat to human health. Inefficient human-to-human transmission of zoonotic strains may initially limit the spread of transmission, but an infection may be contracted by touching contaminated surfaces. Enveloped viruses are often susceptible to environmental stresses, but the human coronaviruses responsible for severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) have recently caused increasing concern of contact transmission during outbreaks. We report here that pathogenic human coronavirus 229E remained infectious in a human lung cell culture model following at least 5 days of persistence on a range of common nonbiocidal surface materials, including polytetrafluoroethylene (Teflon; PTFE), polyvinyl chloride (PVC), ceramic tiles, glass, silicone rubber, and stainless steel. We have shown previously that noroviruses are destroyed on copper alloy surfaces. In this new study, human coronavirus 229E was rapidly inactivated on a range of copper alloys (within a few minutes for simulated fingertip contamination) and Cu/Zn brasses were very effective at lower copper concentration. Exposure to copper destroyed the viral genomes and irreversibly affected virus morphology, including disintegration of envelope and dispersal of surface spikes. Cu(I) and Cu(II) moieties were responsible for the inactivation, which was enhanced by reactive oxygen species generation on alloy surfaces, resulting in even faster inactivation than was seen with nonenveloped viruses on copper. Consequently, copper alloy surfaces could be employed in communal areas and at any mass gatherings to help reduce transmission of respiratory viruses from contaminated surfaces and protect the public health.

Concepts: Lung, Virus, Severe acute respiratory syndrome, Virology, Bronze, Brass, Polyvinyl chloride, Polytetrafluoroethylene

15

The pandemic of hospital acquired infections caused by methicillin-resistant Staphylococcus aureus (MRSA) has declined but the evolution of strains with enhanced virulence, toxins and the increase of community-associated infections is still a threat. In previous studies, simulated droplet contamination of MRSA was killed on copper and brass surfaces within 90 minutes. However, contamination of surfaces is often via finger tips which dries rapidly and may be overlooked by cleaning regimes unlike visible droplets. In this new study a 5-log reduction of a hardy epidemic strain of MRSA (EMRSA-16) was observed following 10 minutes contact with copper and 4-log reduction observed on copper nickel and cartridge brass alloys in 15 minutes. A methicillin-sensitive strain (MSSA), from an osteomyelitis patient, was killed on copper surfaces in 15 minutes and a 4-log and 3-log reduction occurred within 20 minutes contact with copper nickel and cartridge brass, respectively. Bacterial respiration was compromised on copper surfaces and superoxide generated as part of the killing mechanism. In addition, destruction of genomic DNA occurs on copper and brass surfaces allaying concerns about horizontal gene transfer and copper resistance. Incorporation of copper alloy biocidal surfaces could help to reduce the spread of this dangerous pathogen.

Concepts: Gene, Bacteria, Virus, Staphylococcus aureus, Antibiotic resistance, Copper, Bronze, Brass

15

This is a translational science article that discusses copper alloys as antimicrobial environmental surfaces. Bacteria die when they come in contact with copper alloys in laboratory tests. Components made of copper alloys were also found to be efficacious in a clinical trial.

Concepts: Bacteria, Iron, Zinc, Experiment, Laboratory, Alloy, Bronze, Brass

4

The properties of materials change, sometimes catastrophically, as alloying elements and impurities accumulate preferentially at grain boundaries. Studies of bicrystals show that regular atomic patterns often arise as a result of this solute segregation at high-symmetry boundaries, but it is not known whether superstructures exist at general grain boundaries in polycrystals. In bismuth-doped polycrystalline nickel, we found that ordered, segregation-induced grain boundary superstructures occur at randomly selected general grain boundaries, and that these reconstructions are driven by the orientation of the terminating grain surfaces rather than by lattice matching between grains. This discovery shows that adsorbate-induced superstructures are not limited to special grain boundaries but may exist at a variety of general grain boundaries, and hence they can affect the performance of polycrystalline engineering alloys.

Concepts: Iron, Zinc, Copper, Metallurgy, Alloy, Bronze, Alloys, Iron meteorite