Microwave-assisted organic swelling promotes fast and efficient delamination of waste printed circuit boards.

A large amount of waste printed circuit boards (WPCBs) that contain valuable metals, namely gold and copper, are produced annually. WPCBs are constituted by a multi-layer structure reinforced by a brominated epoxy resin (BER), which is very difficult to separate into the metallic and non-metallic components. The main aim of this work was to evaluate the ability of microwave for assisting in the delamination of WPCBs by organic swelling of the BER.

Effects of Charge Density on Photophysics and Aggregation Behavior of Anionic Fluorene-Arylene Conjugated Polyelectrolytes.

Three anionic fluorene-based alternating conjugated polyelectrolytes (CPEs) have been synthesized that have 9,9-bis(4-phenoxy-butylsulfonate) fluorene-2,7-diyl and 1,4-phenylene (PBS-PFP), 4,4'-biphenylene (PBS-PFP2), or 4,4″--terphenylene (PBS-PFP3) groups, and the effect of the length of the oligophenylene spacer on their aggregation and photophysics has been studied. All form metastable dispersions in water, but can be solubilized using methanol, acetonitrile, or dioxane as cosolvents. This leads to increases in their emission intensities and blue shifts in fluorescence maxima due to break-up of aggregates.

Towards the Development of a Low-Cost Device for the Detection of Explosives Vapors by Fluorescence Quenching of Conjugated Polymers in Solid Matrices.

Conjugated polymers (CPs) have proved to be promising chemosensory materials for detecting nitroaromatic explosives vapors, as they quickly convert a chemical interaction into an easily-measured high-sensitivity optical output. The nitroaromatic analytes are strongly electron-deficient, whereas the conjugated polymer sensing materials are electron-rich. As a result, the photoexcitation of the CP is followed by electron transfer to the nitroaromatic analyte, resulting in a quenching of the light-emission from the conjugated polymer.

Platinum(II) Ring-Fused Chlorins as Near-Infrared Emitting Oxygen Sensors and Photodynamic Agents.

Novel near-infrared luminescent compounds based on platinum(II) 4,5,6,7-tetrahydropyrazolo[1,5-]pyridine-fused chlorins are described. These compounds have high photostability and display light emission, in particular simultaneous fluorescence and phosphorescence emission in solution at room temperature, in the biologically relevant 700-850 nm red and near-infrared (NIR) spectral region, making them excellent materials for biological imaging. The simultaneous presence of fluorescence and phosphorescence emission at room temperature, with the phosphorescence strongly quenched by oxygen whereas fluorescence remains unaffected, allows these compounds to be used as ratiometric oxygen sensors in chemical and biological media.

Phasor Representation of Monomer-Excimer Kinetics: General Results and Application to Pyrene.

Phasor plots of the fluorescence intensity decay (plots of the Fourier sine transform versus the Fourier cosine transform, for one or several angular frequencies) are being increasingly used in studies of homogeneous and heterogeneous systems. In this work, the phasor approach is applied to monomer-excimer kinetics. The results obtained allow a clear visualization of the information contained in the decays.

Fluorescence Phasor Plots Using Time Domain Data: Effect of the Instrument Response Function.

Phasor plots of the fluorescence intensity decay (plots of the Fourier sine transform vs the Fourier cosine transform, for one or several angular frequencies) are being increasingly used, namely, in fluorescence lifetime imaging microscopy (FLIM) of cells, tissues, and surfaces, but are also relevant for the characterization of homogeneous (e.g., solution) systems.