Highly luminescent scintillating hetero-ligand MOF nanocrystals with engineered Stokes shift for photonic applications.

Large Stokes shift fast emitters show a negligible reabsorption of their luminescence, a feature highly desirable for several applications such as fluorescence imaging, solar-light managing, and fabricating sensitive scintillating detectors for medical imaging and high-rate high-energy physics experiments. Here we obtain high efficiency luminescence with significant Stokes shift by exploiting fluorescent conjugated acene building blocks arranged in nanocrystals. Two ligands of equal molecular length and connectivity, yet complementary electronic properties, are co-assembled by zirconium oxy-hydroxy clusters, generating crystalline hetero-ligand metal-organic framework (MOF) nanocrystals. The diffusion of singlet excitons within the MOF and the matching of ligands absorption and emission properties enables an ultrafast activation of the low energy emission in the 100 ps time scale. The hybrid nanocrystals show a fluorescence quantum efficiency of ~60% and a Stokes shift as large as 750 meV (~6000 cm-1), which suppresses the emission reabsorption also in bulk devices. The fabricated prototypal nanocomposite fast scintillator shows benchmark performances which compete with those of some inorganic and organic commercial systems.

[Vitamin D as a cardiovascular risk factor in workers]. / La vitamina D come fattore di rischio cardiovascolare nei lavoratori.

Numerous evidence suggests that vitamin D deficiency is implicated in the development of cardiovascular risk. It has been investigated the relationship between cardiovascular risk factors and vitamin D concentrations in 264 consecutive workers from Centro Obesità e Lavoro della Clinica del Lavoro di Milano. For these studies, glicometaboliche analysis, anthropometric measurements and impedance evalutation were performed and questionnaires to estimate nutrient levels in the diet were administered. The levels of vitamin D are found to be deficient in 166 patients (less than 20 ng/mL), insufficient in 63 patients (less than 30 ng/mL) and optimal for the remaining 35 patients. A significant negative association was observed between the concentrations of vitamin D and cardiovascular risk factors (HOMA ratio and TG/HDL) ratios and BMI. Vitamin D is a cardiovascular risk factor "corrected" for example by changing the eating habits of workers.