Soft Body Impact Against Aeronautical Structures

Statistics show that impacts of soft body against aeronautical structure are not so rare events. The damage caused by the impact of hailstones or of birds can sometimes be so heavy to compromise the service life of the vehicle. Companies, research centers and universities are interested in the evaluation of the effects of this kind of events and lots of researching works have been recently developed in this field. In this paper, an overview of the last studies performed at the Laboratory for the Safety in Transports (LaST – Crash Lab.) of Politecnico of Milan are presented throughout experimental tests and numerical finite element models. The validity of the correlation results method to prevent possible heavy consequence caused by these events is shown

Benzylic fluorination induced by N–F bond activation of Selectfluor^® with a solvent-dependent selectivity switch

We present a divergent radical strategy for the fluorination of phenylacetic acid derivatives through N–F bond activation of Selectfluor® with 4-(dimethylamino)pyridine. Comprehensive reaction investigation revealed the critical role of reaction media on selectivity. In presence of water, decarboxylative fluorination through a single electron oxidation is dominant. Non-aqueous conditions result in the clean formation of α-fluoro-α-arylcarboxylic acids through hydrogen atom transfer

Benzylic fluorination induced by a charge-transfer complex with a solvent-dependent selectivity switch

We present a divergent strategy for the fluorination of phenylacetic acid derivatives that is induced by a charge-transfer complex between Selectfluor and 4-(dimethylamino)pyridine. A comprehensive investigation of the conditions revealed a critical role of the solvent on the reaction outcome. In the presence of water, decarboxylative fluorination through a single-electron oxidation is dominant. Non-aqueous conditions result in the clean formation of α-fluoro-α-arylcarboxylic acids

Oneiric stress and safety and security at work: the discovery of a new universal symbol

Cox and Griffiths define as psychosocial risks at work “those aspects of the planning, organization and management of work, which, along with their environmental and social contexts, may affect mental and physical health of the employees, directly or indirectly producing stress”. Therefore, a more effective approach to occupational safety and security should include integrated risk management through the identification of any work stress related problem. The purpose of this paper is to analyze the possible correlation of risk at work with the modification of sleep, and inside it, the specific function of dream activity

Lanthanides: Applications in Cancer Diagnosis and Therapy

Lanthanide complexes are of increasing importance in cancer diagnosis and therapy, owing to the versatile chemical and magnetic properties of the lanthanide-ion 4f electronic configuration. Following the first implementation of gadolinium(III)-based contrast agents in magnetic resonance imaging in the 1980s, lanthanide-based small molecules and nanomaterials have been investigated as cytotoxic agents and inhibitors, in photodynamic therapy, radiation therapy, drug/gene delivery, biosensing, and bioimaging. As the potential utility of lanthanides in these areas continues to increase, this timely review of current applications will be useful to medicinal chemists and other investigators interested in the latest developments and trends in this emerging field

Large-Scale Experimental Static Testing on 50-Year-Old Prestressed Concrete Bridge Girders

The heritage of existing road infrastructures and in particular of bridges consists of structures that are approaching or exceeding their designed service life. Detrimental causes such as aging, fatigue and deterioration processes other than variation in loading conditions introduce uncertainties that make structural assessment a challenging task. Experimental data on their performances are crucial for a proper calibration of numerical models able to predict their behavior and life-cycle structural performance. In this scenario, an experimental research program was established with the aim of investigating a set of 50-year-old prestressed concrete bridge girders that were recovered from a decommissioned bridge. The activities included initial non-destructive tests, and then full-scale load tests followed by a destructive test on the material samples. This paper reports the experimental results of the full-scale tests conducted on the first group of four I-beams assumed to be in good condition from visual inspection at the time of testing. Loading tests were performed using a specifically designed steel reaction frame and a test setup equipment, as detailed in the present work. Due to the structural response of this first group of girders, a uniform behavior was found at both service and ultimate conditions. The failure mechanism was characterized by the crushing of the cast-in-situ top slab corresponding to a limited deflection, highlighting a non-ductile behavior. The outcomes of the experimental research are expected to provide new data for the life-cycle safety assessment of existing bridges through an extended database of validated experimental tests and models

SVILUPPO DI UNA MACCHINA PER PROVE DI TRAZIONE VELOCE

I materiali metallici sottoposti a carichi di natura dinamica vanno soggetti ad un fenomeno noto anche comeincrudimento dinamico.L’incrudimento dinamico ha un’enorme rilevanza nell’ambito della sicurezza passiva. Procedure di prova chepermettano di valutare l’influenza della velocità di deformazione sulle proprietà meccaniche di un materialesono fondamentali per una corretta progettazione di strutture sicure ad impatto.In questo articolo viene presentata una procedura per prove di trazione veloce che prevede l’utilizzo di unaslitta verticale e di una macchina ad inversione.In fase di sviluppo, per verificarne il funzionamento, sono state condotte prove usando provini ottenuti dapiastre di due diversi materiali: un acciaio dolce d’uso comune e una lega leggera di alluminio tipica dellecostruzioni aeronautiche. I dati ottenuti per i due materiali sono ripetibili e confrontati coi dati presenti inbibliografia hanno mostrato che la procedura di prova sviluppata è in grado di fornire dati accurati