Reduction of Hf via Hf/Zr Substitution in Mechanically Alloyed (Hf,Ti)CoSb Half-Heusler Solid Solutions

Abstract (Hf,Zr,Ti)Co(Sb,Sn) Solid solutions were prepared by mechanical-alloying followed by hot-press method as an attempt to reduce Hf concentration and therefore the material’s cost without negatively affecting the thermoelectric performance. To this end, two different methods were applied: (a) Hf substitution with its lighter and cheaper homologue Zr; and (b) fine tuning of carrier concentration by the substitution of Sb with Sn. The isoelectronic substitution of Hf with Zr was investigated in Hf0.6-xZrxTi0.4CoSb0.8Sn0.2 solid solutions and resulted in lower power factors and ZTs. However, the low thermal conductivity of Hf0.4Zr0.2Ti0.4CoSb0.8Sn0.2 contributed in achieving a relatively good ZT~0.67 at 970 K. The effect of charge carrier concentration was investigated by preparing Hf0.4Zr0.2Ti0.4CoSb1-ySny (y = 0.15–0.25) compounds. Hf0.4Zr0.2Ti0.4CoSb0.83Sn0.17 composition prepared by six hours milling reached the highest ZT of 0.77 at 960 K.publishedVersio

Simplified model for pre-code RC column exposed to fire followed by earthquake

The behaviour of pre-code reinforced concrete (RC) columns in sequence of fire and earthquake is not well understood and can be critical in case of buildings which experienced fire and are either unrepaired or poorly repaired when exposed to an earthquake. This study proposes a framework on how to construct a simplified model to assess the post-fire cyclic behaviour of such columns. Emphasis is given to the development of simplified material models which can be used to describe the performance of the confined concrete, as its post-fire behaviour is not well studied. The model's performance is validated against the experimental results of a square, non-seismically designed RC column. Three scenarios are considered. The reference scenario, where the column is exposed only to cyclic loading. In the other two, the column is firstly exposed to an ISO-834 time-temperature curves in a furnace of 30 min and 90 min duration and after it cooled down, it is exposed to cyclic loading. The results showed that simplified material models can be used to capture the post-fire cyclic behaviour of an RC column, built without seismic design. It was also found that the confined model adopted played an important role after the peak strength is reached

Detection of somatostatin receptors in human osteosarcoma

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Experimental assessment of post-fire retrofitted RC columns tested under cyclic loading

Multiple combined hazards can affect the structures during their live span and may conditionate the future structural behaviour for some types of loading. That is the case of a structure previously damaged by fire and then loaded under seismic loading. For seismic hazard zones it is important assess the seismic performance of existing reinforced concrete (RC) structures designed according to old codes and without seismic detailing. This structural seismic assessment is even more important for buildings that were previously damaged by fire. Therefore, it is critical develop and validate fire retrofitting methods that can also improve the seismic behaviour. This paper presents the results of a novel experimental campaign carried out on four (two of them repaired and strengthened with CFRP wrapping after fire exposure) full-scale reinforced concrete columns previously damaged by a 30 or 90 minutes standard fire and then tested under uniaxial cyclic lateral loading up to failure. Moreover, two additional control columns, one as-built and another strengthened, were cyclically tested for comparison. A considerable decrease in the deformation capacity and dissipated energy was observed in the columns after fire exposure, even for the 30 minute fire. Moreover, the post-fire repaired and strengthened columns may reach similar seismic performance than analogous strengthened columns without previous fire damages

Prioritization of hazards for risk and resilience management through elicitation of expert judgement

Risk assessment in communities or regions typically relies on the determination of hazard scenarios and an evaluation of their impact on local systems and structures. One of the challenges of risk assessment for infrastructure operators is how to identify the most critical scenarios that are likely to represent unacceptable risks to such assets in a given time frame. This study develops a novel approach for prioritizing hazards for the risk assessment of infrastructure. Central to the proposed methodology is an expert elicitation technique termed paired comparison which is based on a formal mathematical technique for quantifying the range and variance in the judgements of a group of stakeholders. The methodology is applied here to identify and rank natural and operational hazard scenarios that could cause serious disruption or have disastrous effects to the infrastructure in the transnational Øresund region over a period of 5 years. The application highlighted substantial divergences of views among the stakeholders on identifying a single 'most critical' natural or operational hazard scenario. Despite these differences, it was possible to flag up certain cases as critical among the natural hazard scenarios, and others among the operational hazards