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This work describes a very efficient methodology for the methanolysis of polyester and polycarbonate plastic waste into a variety of valuable products using homogeneous and heterogeneous manganese compounds in the presence of KOtBu. Excellent yields are obtained using 1 mol% of the homogeneous catalysts Mn(OTf)2, Mn2(CO)10, MnBr(CO)5, and MeCpMn(CO)3 and 5 mol% of KOtBu, under mild reaction conditions. The heterogeneous manganese catalyst, manganese(II) ethyl/butyl phosphonate silica (Si‐Mn), also successfully promoted the methanolysis of polyester and polycarbonate plastic waste with excellent yields. Furthermore, this heterogeneous catalyst can be applied in at least 12 catalytic cycles with excellent yields. [ABSTRACT FROM AUTHOR]

The use of alkaline earth‐abundant metal catalysts as alternatives to transition metal catalysts in the depolymerization of plastic waste is a very important research area. In this work, the first method is described for the conversion of polyesters into value‐added compounds catalyzed by a magnesium catalyst. It is demonstrated that the commercially available, inexpensive and air‐stable, alkaline earth magnesium catalyst Mg(OTf)2 efficiently promotes the reductive depolymerization of several polyesters using pinacolborane (HBpin) as the reducing agent with good to excellent yields. This catalyst also remains very active in at least 12 consecutive polycaprolactone (PCL) reductive depolymerization reactions with yields between 89% and 81%. This magnesium catalyst is also efficient in the reductive depolymerization of the polycarbonate poly(bisphenol A carbonate) (PC.BPA). Furthermore, it is found that Mg(OTf)2 also successfully catalyzes the methanolysis of polyesters and polycarbonates at moderate temperature with excellent yields. [ABSTRACT FROM AUTHOR]

This work describes the depolymerization of several polyester and polycarbonate plastic waste in value‐added compounds catalyzed by the air stable, cheap and commercially available manganese compounds Mn(OTf)2, Mn2(CO)10, MnBr(CO)5, and MeCpMn(CO)3 using boranes and silanes as the reducing agents with good to excellent yields. Commercial heterogeneous manganese catalyst, manganeses(II) ethyl/butyl phosphonate silica (Si‐Mn), has also proven to be very efficient in the reductive depolymerization of a variety of polyesters and the polycarbonate PC.BPA. The use of Mn(OTf)2, Mn2(CO)10 and Si‐Mn in consecutive depolymerization of polyesters is also investigated, showing that these catalysts remain their excellent activity after several reactions. [ABSTRACT FROM AUTHOR]

Neutron production yields and energy distributions from (α,n) reactions in light elements were calculated using three different codes (SOURCES, NEDIS and USD) and compared with the existing experimental data in the 3.5-10 MeV alpha energy range. SOURCES and NEDIS display an agreement between calculated and measured yields in the decay series of 235U, 238U and 232Th within ±10% for most materials. The discrepancy increases with alpha energy but still an agreement of ±20% applies to all materials with reliable elemental production yields (the few exceptions are identified). The calculated neutron energy distributions describe the experimental data, with NEDIS retrieving very well the detailed features. USD generally underestimates the measured yields, in particular for compounds with heavy elements and/or at high alpha energies. The energy distributions exhibit sharp peaks that do not match the observations. These findings may be caused by a poor accounting of the alpha particle energy loss by the code. A big variability was found among the calculated neutron production yields for alphas from Sm decay; the lack of yield measurements for low (~2 MeV) alphas does not allow to conclude on the codes’ accuracy in this energy region.

Superheated droplet detectors are a promising technique to the measurement of low-intensity neutron fields, as detectors can be rendered insensitive to minimum ionizing radiations. We report on the intrinsic neutron-induced signal of C2ClF5 devices fabricated by our group that originate from neutron- and alpha-emitting impurities in the detector constituents. The neutron background was calculated via Monte Carlo simulations using the MCNPX-PoliMi code in order to extract the recoil distributions following neutron interaction with the atoms of the superheated liquid. Various nuclear techniques were employed to characterise the detector materials with respect to source isotopes (238U, 232Th and 147Sm) for the normalisation of the simulations and also light elements (B, Li) having high (α, n) neutron production yields. We derived a background signal of ~10-3 cts/day in a 1 liter detector of 1-3 wt.% C2ClF5, corresponding to a detection limit in the order of 10-8 n cm-2s-1. Direct measurements in a massively shielded underground facility for dark matter search have confirmed this result. With the borosilicate detector containers found to be the dominant background source in current detectors, possibilities for further noise reduction by ~2 orders of magnitude based on selected container materials are discussed.

The formation of complexes of the drug 5-fluorouracil (5-FU) with β-cyclodextrin (β-CD) and sodium dodecyl sulphate (SDS) was studied through experimental measurements of the ternary mutual diffusion coefficients (D11, D22, D12, and D21) for the systems {5-FU (component 1) + β-CD (component 2) + water} and {5-FU (component 1) + SDS (component 2) + water} at 298.15 K and at concentrations up to 0.05 mol dm−3 by using the Taylor dispersion method, with the objective of removing this polluting drug from the residual systems in which it was present. The results found showed that a coupled diffusion of 5-FU occurred with both β-CD and SDS, as indicated by the nonzero values of the cross-diffusion coefficients, D12 and D21, as a consequence of the complex formation between 5-FU and the β-CD or SDS species. That is, 5-FU was solubilized (encapsulated) by both carriers, although to a greater extent with SDS (K = 20.0 (±0.5) mol−1 dm3) than with β-CD (K = 10.0 (±0.5) mol−1 dm3). Values of 0.107 and 0.190 were determined for the maximum fraction of 5-FU solubilized with β-CD and SDS (at concentrations above its CMC), respectively. This meant that SDS was more efficient at encapsulating and thus removing the 5-FU drug. [ABSTRACT FROM AUTHOR]

We propose to apply the superheated droplet detector (SDD) technology to the measurement of alpha-particle emissivity on integrated circuits of ultra-low activity grade (