New Silver(I) Coordination Polymer with Fe4 Single-Molecule Magnets as Long Spacer

In continuation of our work on supramolecular architectures of single-molecule magnets (SMMs) as a promising strategy in developing their magnetic performance, in this paper we report the synthesis and single crystal X-ray structure of the centered triangular tetrairon(III) SMM, [Fe4(PhpPy)2(dpm)6], Fe4 (Hdpm = dipivaloylmethane, H3PhpPy = 2-(hydroxymethyl)- 2-(4-(pyridine-4-yl)phenyl)propane-1,3-diol), and its assembly in the coordination polymer {[Fe4(PhpPy)2(dpm)6Ag](ClO4)}n, Fe4Ag, upon reaction with silver(I) perchlorate. Thanks to the presence of the pyridyl rings on the two tripodal ligands, Fe4 behaves as divergent ditopic linker, and due to the Fe4:AgClO4 1:1 ratio, Fe4Ag probably possesses a linear arrangement in which silver(I) ions are linearly coordinated by two nitrogen atoms, forming 1D chains whose positive charge is balanced by the perchlorate anions. The stabilization of such a polymeric structure can be ascribed to the long distance between the two donor nitrogen atoms (23.4 \uc5) and their donor power. Fe4Ag shows slow relaxation of the magnetization which follows a thermally activated process with Ueff/kB = 11.17(18) K, t0 = 2.24(17) 107 s in zero field, and Ueff/kB = 14.49(5) K, t0 = 3.88(8) 107 s in 1-kOe applied field, in line with what reported for tetrairon(III) SMMs acting as building blocks in polymeric structures

Exploring the potential of peach (Prunus Persica L.) nut-shells as a sustainable alternative to traditional aggregates in lightweight concrete

This study investigates the potential application of peach shells as lightweight aggregates in the production of non-structural lightweight concrete (LWC). The recycling and reutilization of agri-food waste presents an opportunity to address the challenges associated with waste disposal and limit the exploitation of natural resources, contributing to sustainable development goals and combatting climate change. The peach shells were subjected to heat treatment at various temperatures (160, 200, and 240 °C) to reduce the hydrophilicity of the cellulose fraction, and their chemical and physical properties were examined in relation to the performance of lightweight concrete, in terms of density, compressive strength and thermal conductivity. Two binding mixtures, one with lime only (mixture “a”) and the other with both lime and cement (mixture “b”), were studied. The experimental results indicated that the prepared lightweight concrete specimens exhibited better performance as the roasting temperature increased, starting from 200 °C. Conversely, specimens prepared with peach shells roasted at 160 °C exhibited a decreased performance compared to those prepared with only air-dried peach shells. Samples prepared with the mixture “a” have better insulating properties and lower density, but lower mechanical resistance. The enhanced properties observed in the lightweight concrete specimens prepared with higher roasting temperatures highlight the potential of utilizing peach shells as an effective and sustainable alternative to traditional lightweight aggregates

Upgrading of Biobased Glycerol to Glycerol Carbonate as a Tool to Reduce the CO2 Emissions of the Biodiesel Fuel Life Cycle

With regards to oil-based diesel fuel, the adoption of bio-derived diesel fuel was estimated to reduce CO2 emissions by approximately 75%, considering the whole life cycle. In this paper, we present a novel continuous-flow process able to transfer an equimolar amount of CO2 (through urea) to glycerol, producing glycerol carbonate. This represents a convenient tool, able to both improve the efficiency of the biodiesel production through the conversion of waste streams into added-value chemicals and to beneficially contribute to the whole carbon cycle. By means of a Design of Experiments approach, the influence of key operating variables on the product yield was studied and statistically modeled

Graphite/epoxy composite for building Bipolar Plates

Bipolar plates (BPs) are important components of Proton Exchange Membrane Fuel Cells (PEMFC). Graphite-epoxy composites, having a better corrosion resistance than metal-based BPs and better mechanical properties than graphite BPs, are a promising alternative. In this study, we tried to develop graphite-epoxy composites meeting the technical US DOE targets for 2020, with a proper choice of manufacturing conditions that ensure a good compromise between conductivity, flexural strength, and gas permeability. In particular, we studied the influence of the filler to binder ratio, changed the molding temperature and time, and investigated the effects of increasing pressure both on in-plane conductivity and on helium permeability. We found that both formulation and molding pressure are crucial in determining the permeability of the graphite-epoxy composites, whereas molding temperature and time seem to play a minor role

Particle Content of the Nonlinear Sigma Model with Theta-Term: a Lattice Model Investigation

Using new as well as known results on dimerized quantum spin chains with frustration, we are able to infer some properties on the low-energy spectrum of the O(3) Nonlinear Sigma Model with a topological theta-term. In particular, for sufficiently strong coupling, we find a range of values of theta where a singlet bound state is stable under the triplet continuum. On the basis of these results, we propose a new renormalization group flow diagram for the Nonlinear Sigma Model with theta-term.Comment: 10 pages, 5 figures .eps, iopart format, submitted to JSTA

Simultaneous deprotection-oxydation of cyclic hemiacetals: a fine ending for the Ueno-Stork ATRC to dichloro-gamma-lactones

Recently we found that a copper catalysed Ueno\u2013Stork cyclization can be a very useful means for the expedient synthesis of dichloro-\u3b3-lactones, but, to take advantage of this step, the method still lacks of an efficient and selective follow-up. This Letter describes our progress in that field, unveiling the use of a supported and recyclable Cr(VI) catalyst for the simultaneous deprotection and oxidation of cyclic dichloro hemiacetals