Refinement of the microstructure of light alloys using ultrasonic and laser processing

The transport sector represents 20 pct of all greenhouse gas emissions globally. The use of aluminum (Al) to reduce vehicle weight offers the potential to reduce these emissions. The production of secondary Al from recycled products requires only ~2.8 kWh kg 1 compared to ~45 kWh kg 1 for primary Al production. In addition, recycling emits only ~5 pct as much carbon dioxide as primary production. Hence, the environmental advantages of using recycled Al for transport applications are as attractive as the economic savings. Unfortunately, the properties of recycled Al alloys do not meet the necessary requirements due to the unavoidable introduction of iron (Fe) impurity that leads to the occurrence of harmful Fe containing intermetallic compounds (IMCs). This thesis aims to establish the knowledge required to be able to increase the utilization of recycled Al by controlling the formation of the Fe containing IMCs by ultrasonic melt treatment (USMT). In addition, USMT was further extended to laser additive manufacturing (LAM) to explore its applicability for structural refinement

Elastic properties of two-component grouts at short curing times: The role of bentonite

Two-component grout is nowadays the material most used for the backfilling phase in tunnelling with a shield machine. The operative simplicity of the technology and the fast hardening reaction between the two components are the main reasons that have contributed to the intensive spread of the use of this backfilling technique all around the world. Although bentonite is one of the basic ingredients for the grout production, its effect on the elastic properties of the grout has not been completely investigated so far. In this work, six different two-component grouts and their elastic properties have been studied by means of geophysical measurements. The six grouts were characterised by the same mix design and five different bentonites, while one grout had no bentonite. The variation of the dynamic parameters over time was analysed at short curing times (up to 24 h). In detail, the shear wave velocity, the dynamic moduli and Poisson's ratio were determined by means of the ultrasonic pulse velocity technique. The results show that the grouts with the bentonites have higher dynamic moduli than the grout without the bentonite. Moreover, a final analysis of the experimental data provided an analytical relationship to calculate the shear-wave velocity for each of the six grouts at any curing times

Analysis of microbiological variation in PDO Vastedda della valle del Belìce cheese during the storage period

The PDO “Vastedda della valle del Belìce” is a Sicilian pasta filata sheep cheese, made from raw milk without starter addition. It is a small round cheese without rind, weighing about 500-700 g. It is cheese is marketed also out of Sicily to allow its marketing and to prolong its shelf-life. The aim of this work was to evaluate the variation of microbiological parameters during the shelf-life period. Then 162 Vastedda cheeses from 18 cheese-making processes in 7 farms have been analysed at different times of storage at 4°C (0, 15, 30, 45, 60, 75, 90, 105, 120 days). Coliforms and E. coli were detected into 7/18 cheese-making processes and their count decreased during the storage period. Enterococci were more resistant to high temperature achieved during the stretching and their were rather stable during storage period (105 cfu/g). The concentration of total Bacterial Count and Mesophilic Lactococci were around 107 cfu/g, while the concentration of Thermophilic Lactococci was higher (108 cfu/g) probably due to the stretching at 90°C. In conclusion, this study shows the good sanitary conditions of cheeses. Overall, the lactic flora was kept alive and vital at high concentration (> 107 cfu/g) until 120 days of storage

Bentonite in two-component grout applications

Two-component grout is a cement-based material, currently the most used technology for backfilling in tunnelling applications. Despite its intensive, knowledge on this material is quite limited, especially as concern the role of ingredients and their effect on the properties of fresh mortar and hardened grout. In this work, an accurate and innovative test campaign focused on the role of the bentonite was performed. Three different bentonites were used. The activation of the bentonite and its effect on both mortar stability and grout strength was investigated with the purpose to recognise the bentonite parameters useful to select, at the design stage, the best bentonite according to the designers’ requirements. Swell index and Atterberg's liquid limit were recognised as useful parameters for predicting results in terms of suitable bleeding and surface compression strength

Comparison of the Results of Analytical and Numerical Models of Pre-Reinforcement in Shallow Tunnels

AbstractThe steel pipe umbrella is a widely used technology when tunnelling in weak soils in order to create pre-support ahead of the tunnel face. The design of steel pipes is frequently done through simplified analytical approaches which are easy to apply but require proper assessment of the loads acting on the pipe. To provide information on this key design aspect, the results of the comparison between a three-dimensional numerical model developed with the code FLAC 3D and an analytical model based on the approach of a beam on yielding supports is presented and discussed. The comparison refers to a shallow tunnel with an overburden of three times its diameter for two different types of weak rock masses. The obtained results provide suggestions about the load that has to be applied in the analytical model for the design phase

MiR-205-5p inhibition by locked nucleic acids impairs metastatic potential of breast cancer cells

Mir-205 plays an important role in epithelial biogenesis and in mammary gland development but its role in cancer still remains controversial depending on the specific cellular context and target genes. We have previously reported that miR-205-5p is upregulated in breast cancer stem cells targeting ERBB pathway and leading to targeted therapy resistance. Here we show that miR-205-5p regulates tumorigenic properties of breast cancer cells, as well as epithelial to mesenchymal transition. Silencing this miRNA in breast cancer results in reduced tumor growth and metastatic spreading in mouse models. Moreover, we show that miR-205-5p knock-down can be obtained with the use of specific locked nucleic acids oligonucleotides in vivo suggesting a future potential use of this approach in therapy

Analysis of the foam penetration in the EPB excavation

Nowadays, the problem of reduction of environmental impact about construction of underground buildings is one of the main issue discussed during design phase. Foams, essential for EPB, consist of biodegradables surfactants which are injected in pressure ahead the cutterhead, inside the excavating chamber and along the screw conveyor. The present work aims to understand the process of foam diffusion through saturated media by using a new experimental procedure

A More Comprehensive Way to Analyze Foam Stability for EPB Tunnelling—Introduction of a Mathematical Characterization

In the tunnelling industry, a large share of the market is occupied by EPB (Earth Pressure Balance) machines. To operate this kind of machine, a radical change in the rheological behaviour of the excavated soil must be performed, and this is achieved by adding water, foam, and, eventually, polymers. The stability of the foam is assessed through a half-life test. The main limitation of this test is that only one value is used in the characterization of the foam degradation process, which is insufficient to describe the whole evolution of the phenomenon. The results of more than 270 tests were modelled through a five-parameter mathematical formulation that suited the experimental data. The results show that the influence of concentration on the stability of the foam is not always present and that the flow rate used during production bears an influence on the characteristics of the foam