Calcium looping spent sorbent as a limestone replacement in the manufacture of portland and calcium sulfoaluminate cements.

The calcium looping (CaL) spent sorbent (i) can be a suitable limestone replacement in the production of both ordinary Portland cement (OPC) and calcium sulfoaluminate (CSA) cement, and (ii) promotes environmental benefits in terms of reduced CO2 emission, increased energy saving and larger utilization of industrial byproducts. A sample of CaL spent sorbent, purged from a 200 kWth pilot facility, was tested as a raw material for the synthesis of two series of OPC and CSA clinkers, obtained from mixes heated in a laboratory electric oven within temperature ranges 1350°-1500 °C and 1200°-1350 °C, respectively. As OPC clinker-generating mixtures, six clay-containing binary blends were investigated, three with limestone (reference mixes) and three with the CaL spent sorbent.

Fast and stable photochromic oxazines for fluorescence switching.

The stringent limitations imposed by diffraction on the spatial resolution of fluorescence microscopes demand the identification of viable strategies to switch fluorescence under optical control. In this context, the photoinduced and reversible transformations of photochromic compounds are particularly valuable. In fact, these molecules can be engineered to regulate the emission intensities of complementary fluorophores in response to optical stimulations.

Photoswitchable fluorescent dyads incorporating BODIPY and [1,3]oxazine components.

We designed and synthesized three compounds incorporating a BODIPY fluorophore and an oxazine photochrome within the same molecular skeleton and differing in the nature of the linker bridging the two functional components. The [1,3]oxazine ring of the photochrome opens in less than 6 ns upon laser excitation in two of the three fluorophore-photochrome dyads. This process generates a 3H-indolium cation with a quantum yield of 0.

Fluorescence patterning in films of a photoswitchable BODIPY-spiropyran dyad.

A BODIPY-spiropyran dyad was embedded within poly(methyl methacrylate) films spin-coated on glass slides. Visible illumination of the resulting materials excites selectively the BODIPY fragment, which then deactivates radiatively by emitting light in the form of fluorescence. Ultraviolet irradiation promotes the isomerization of the spiropyran component to the corresponding merocyanine.

Hydrophilic and photochromic switches based on the opening and closing of [1,3]oxazine rings.

In search of strategies to operate photochromic compounds in aqueous environments, we synthesized two oxazines with a pendant oligo(ethylene glycol) chain each and a co-polymer with multiple oxazine and oligo(ethylene glycol) tails appended to a common macromolecular backbone. The hydrophilic character of the oligo(ethylene glycol) chains imposes solubility in water on two of the three systems. Their laser excitation in water opens the oxazine ring in less than 6 ns to generate zwitterionic isomers able to absorb in the visible region of the electromagnetic spectrum.