Lorna Anguilano

Fabrication and characterization of a biodegradable Mg–2Zn–0.5Ca/1β-TCP composite

A biodegradable magnesium matrix and beta-tricalcium phosphate (β-TCP) particles reinforced composite Mg-2Zn-0.5Ca/1beta-TCP (wt.%) was fabricated for biomedical applications by the novel route of combined high shear solidification (HSS) and equal channel angular extrusion (ECAE). The as-cast composite obtained by HSS showed a fine and equiaxed grain structure with globally uniformly distributed β-TCP particles in aggregates of 2-25 μm in size. The ECAE processing at 300 °C resulted in further microstructural refinement and the improvement of β-TCP particle distribution. During ECAE, the β-TCP aggregates were broken into smaller ones or individual particles, forming a dispersion in the matrix. Such fabricated composite exhibited enhanced hardness and in vitro corrosion resistance. The enhanced hardness was attributed to both the addition of β-TCP particles and grain refinement while the development of a Ca-P rich surface layer from β-TCP during corrosion was responsible for the improvement in corrosion resistance. The composite was characterized in terms of microstructural evolution during fabrication, mechanical properties and electrochemical performance during polarization and immersion tests in a simulated body fluid. Discussions are made on the benefits of both HSS and ECAE and the mechanisms responsible for the enhanced corrosion resistance.

A trapped magnetic field of 3T in homogeneous, bulk MgB2 superconductors fabricated by a Modified Precursor Infiltration and Growth (MPIG) process

The wetting of boron with liquid magnesium is a critical factor in the synthesis of MgB2 bulk superconductors by the infiltration and growth (IG) process. Poor wetting characteristics can therefore result potentially in non-uniform infiltration, formation of defects in the final sample structure and poor structural homogeneity throughout the bulk material. Here we report the fabrication of near-net-shaped MgB2 bulk superconductors by a modified precursor infiltration and growth (MPIG) technique. A homogeneous bulk microstructure has subsequently been achieved via the uniform infiltration of Mg liquid by enriching pre-reacted MgB2 powder within the green precursor pellet as a wetting enhancer, leading to relatively little variation in superconducting properties across the entire bulk sample. Almost identical values of trapped magnetic field of 2.12 T have been measured at 5 K at both the top and bottom surfaces of a sample fabricated by the MPIG process, confirming the uniformity of the bulk microstructure. A maximum trapped field of 3 T has been measured at 5 K at the centre of a stack of two bulk MgB2 samples fabricated using this technique. A steady rise in trapped field was observed for this material with decreasing temperature down to 5 K without the occurrence of flux avalanches and with a relatively low field decay rate (1.5%/d). These properties are attributed to the presence of a fine distribution of residual Mg within the bulk microstructure generated by the MPIG processing technique.

Operation of a modified anaerobic baffled reactor coupled with a membrane bioreactor for the treatment of municipal wastewater in Taiwan

ABSTRACT A modified anaerobic baffled reactor (ABR) combined with a submerged membrane bioreactor (MBR) was applied to treat municipal wastewater. The performance of this process was examined in terms of the removal of organic matter, suspended solids, turbidity and nitrogen. The raw wastewater was fed to the 105 L ABR and then the treated effluent was driven to a 58 L MBR equipped with a submerged hollow fibre ultrafiltration membrane module. The integrated modified ABR–MBR process resulted in the complete removal of total suspended solids (TSS) and in very high chemical oxygen demand (COD) removal (93.3u2009±u20093.8%). Furthermore, the recycling of mixed liquor from the MBR to the modified ABR resulted in some denitrification occurring in the first compartment of the ABR, resulting in 53u2009±u20096% removal of nitrogen by the integrated process. The membrane flux was stable and above 20u2005L/m2h. Membrane examination at the nanoscale indicated the deposition of small particles on the surface of the membranes.

Under the surface: silvering in Adrian Athenaeum

Abstract The recovery of a metal workshop dated to the sixth century AD, superimposed to the Hadrian’s Athenaeum in Piazza Madonna di Loreto, Rome, provided the opportunity to identify a series of metallurgical processes linked to the two chaînes opératoires related to copper, bronze, silver and lead productions. Some analysed fragments presented superficial treatment identified as silvering, the focus of this paper. The main aim is to investigate the signs of the surface treatment on the artefacts and discuss what methods would be best employed to analyse and interpret them in order to identify the process to which they relate. Different analytical techniques were used to obtain information on the superficial layer, and their pros and cons are presented so as to discuss how analytical limits can affect the interpretation of a process and the identification of an object. The conclusions reached here are necessarily limited because of the scarce number of samples analysed and the techniques used.

Metalworking Evidence from a Late Antique Context in the Forum of Grumentum

ABSTRACT This paper is a preliminary report on metallurgical activity detected in the Forum of the ancient city of Grumentum ( Basilicata, Italy). In the Late antique period, an area next to one of the most important temples of the square was turned into a metalworking structure, which has yielded a set of hearths, metallurgical remains, and some tools. The results of archaeometrical investigation on the debris are reported and discussed, together with a general analysis of the archaeological context, also in comparison with other similar evidence detected elsewhere in Italy.

Evidence of Circular Economy in Roman Northern Italy: Bronze Casting Technology

In several recent excavations carried out in Northern Italy, archaeologists have encountered the remains of metalworkers’ workshops where, in the Roman imperial period, large bronze objects were cast. The significance of these finds is considerable as, although the high levels of craftsmanship achieved by Roman bronze workers in the region are undisputed, little is still known regarding the layout of the workshops and the technologies used. The present research, still in its early stage, deals with the metalworking evidence from two bronze working sites located in Vimercate (Milan) and Verona, where remarkably well-preserved evidence was found, for instance, large casting pits, moulds and metalworking debris. A thorough review of the archaeological stratigraphy was carried out, in order to trace back the working processes and, where possible, the structure of the workshops. Moreover, archaeometric analyses were performed on both refractories and metal residues, aiming at reconstructing technological aspects. Analyses of slags, in particular, are meaningful because they help to retrace technical choices and patterns.

Metallurgical Evidence From a Late Antique Context in the Forum of Grumentum

ABSTRACTThis article is a preliminary report on metallurgical activity detected in the Forum of the ancient city of Grumentum (Basilicata, Italy). In an area next to one of the most important temples of the square, a set of hearths belonging to a metallurgical plant was brought to light and investigated, together with a great quantity of metallurgical remains, a tuyere, and a fragment of what might be identified as an iron crucible: according to stratigraphic evidence and the preliminary data from the study of pottery sherds, this intense metallurgical activity seems to be dating to the Late Antique period. It is not clear yet if it has some relationship with the abandonment of the Forum itself.