A deformational and configurational framework for geometrically non-linear continuum thermomechanics coupled to diffusion

A general framework encompassing both the (conventional) deformational and configurational settings of continuum mechanics is presented. A systematic application of balance principles over a migrating control volume in the undeformed configuration of the continuum body yields the system of governing equations in the bulk, on the surface and on a coherent interface within the continuum. The equations governing the response of the bulk agree with those of the conventional deformational approach. The localised balance equations are expressed in the configurational setting using a pull-back operator and reformulated in terms of the Eshelby stress. The configurational expression of the dissipation elucidates the energy loss associated with configurational changes. The general framework is introduced by considering the problem of coupled deformation, heat conduction and species diffusion within a geometrically non-linear continuum body intersected by a coherent interface. The nature of the coupling is emphasised throughout the presentation and via an example.     

An incremental variational formulation of dissipative and non-dissipative coupled thermoelasticity for solids

In the early 1990s, Green and Naghdi introduced a theory attracting interest as heat propagates as thermal waves at finite speed and does not necessarily involve energy dissipation. Another outstanding property of the so-called theory of type II is the fact that the entropy flux vector is determined by means of the same potential as the mechanical stress tensor. Motivated by the procedure of [9, 15], we formulate a variational formulation within the incremental framework for coupled thermoelasticity for type I mimicing type II. The entropy flux of type II is determined via the free energy acting as a potential. This is not possible for the classical Fourier case in the continuous setting. Therefore, we target a derivation of an incremental entropy flux following Fourier’s law by means of incremental potentials similar to the spirit of the theory of the non-dissipative Green–Naghdi-type II. Subsequently, we show that the resulting update algorithm is a convenient fully coupled finite element formulation of the proposed thermoelastic problem.     

Phosphane Copper(I) Dicarboxylates: Synthesis and Their Potential Use as Precursors for the Spin‐coating Process in the Deposition of Copper

Dicopper dicarboxylates [(R₃P)_mCuXCu(PR₃)_m] ( 5a , X = O₂CCO₂, R = Ph, m = 2; 5b , X = O₂CCO₂, R = nBu, m = 3) were prepared by treatment of [Cu₂O] ( 1a ) with HO₂CCO₂H ( 2a ) in presence of PR₃ ( 4a , R = Ph; 4b , R = nBu). A further synthesis approach to mono‐ and dicopper dicarboxylates is given using an electrolysis cell equipped with Cu electrodes and charged with acids H₂X and phosphanes R₃P. Without addition of a base mononuclear [(nBu₃P)_mCuXH] ( 6a , m = 3, XH = O₂CCO₂H, 6b , m = 3, XH = O₂CCH₂CO₂H, 6c , m = 3, XH = O₂CCH₂CH₂CO₂H, 6d , m = 2, XH = O₂C‐2‐C₅H₄N‐6‐CO₂H) was formed, whereas in presence of NEt₃ ( 3 ), the dicopper systems [(R₃P)_mCuXCu(PR₃)_m] ( 5a , X = O₂CCO₂, R = Ph, m = 2; 5b , X = O₂CCO₂, R = nBu, m = 3; 5c , X = O₂CCH₂CO₂, R = nBu, m = 3; 5d , X = O₂CCH₂CH₂CO₂, R = nBu, m = 3; 5e , X = O₂C‐2‐C₅H₄N‐6‐CO₂, R = nBu, m = 3) were produced. When 6a reacted with [(tmeda)Zn(nBu)₂] ( 7 ), trimetallic [(tmeda)Zn((nBu₃P)₃CuO₂CCO₂)₂] ( 8 ) was accessible. In this heterobimetallic complex the Zn(tmeda) unit spans two CuO₂CCO₂ entities. The molecular structures of 5a , 6a and 6d in the solid state were determined by single X‐ray structure analysis. Complexes 5a and 6a are monomers, whereas 6d creates in the solid state a linear open chain coordination polymer by hydrogen bridge formation. Characteristic for 6d is the somewhat distorted trigonal bipyrimidal arrangement around the copper atom with the nBu₃P ligands in axial and the C₅H₃NCO₂H oxygen and nitrogen atoms in equatorial positions. In 5a the oxalate connectivity binds in a μ‐1,2,3,4 fashion being part of a planar Cu₂(oxalate) core. TG studies of several mono‐ and dicopper dicarboxylates were carried out. Release of the PR₃ ligands is recognized and the remaining Cu‐(di)carboxylate unit decomposes to afford elemental copper and CO₂. The deposition of copper onto pieces of PVD‐Cu oxidized silicon wafers by applying the spin‐coating process and using 5c and 5d as precursors is discussed.     

In Situ Spectroscopic Detection of Large-Scale Reorientations of Transmembrane Helices During Influenza A M2 Channel Opening**

Viroporins are small ion channels in membranes of enveloped viruses that play key roles during viral life cycles. To use viroporins as drug targets against viral infection requires in-depth mechanistic understanding and, with that, methods that enable investigations under in situ conditions. Here, we apply surface-enhanced infrared absorption (SEIRA) spectroscopy to Influenza A M2 reconstituted within a solid-supported membrane, to shed light on the mechanics of its viroporin function. M2 is a paradigm of pH-activated proton channels and controls the proton flux into the viral interior during viral infection. We use SEIRA to track the large-scale reorientation of M2’s transmembrane α-helices in situ during pH-activated channel opening. We quantify this event as a helical tilt from 26° to 40° by correlating the experimental results with solid-state nuclear magnetic resonance-informed computational spectroscopy. This mechanical motion is impeded upon addition of the inhibitor rimantadine, giving a direct spectroscopic marker to test antiviral activity. The presented approach provides a spectroscopic tool to quantify large-scale structural changes and to track the function and inhibition of the growing number of viroporins from pathogenic viruses in future studies.