Temporal nanofluid environments induce prebiotic condensation in water.

Water is a problem in understanding chemical evolution towards life's origins on Earth. Although all known life is being based on water key prebiotic reactions are inhibited by it. The prebiotic plausibility of current strategies to circumvent this paradox is questionable regarding the principle that evolution builds on existing pathways. Here, we report a straightforward way to overcome the water paradox in line with evolutionary conservatism. By utilising a molecular deposition method as a physicochemical probe, we uncovered a synergy between biomolecule assembly and temporal nanofluid conditions that emerge within transient nanoconfinements of water between suspended particles. Results from fluorometry, quantitative PCR, melting curve analysis, gel electrophoresis and computational modelling reveal that such conditions induce nonenzymatic polymerisation of nucleotides and promote basic cooperation between nucleotides and amino acids for RNA formation. Aqueous particle suspensions are a geochemical ubiquitous and thus prebiotic highly plausible setting. Harnessing nanofluid conditions in this setting for prebiotic syntheses is consistent with evolutionary conservatism, as living cells also work with temporal nanoconfined water for biosynthesis. Our findings add key insights required to understand the transition from geochemistry to biochemistry and open up systematic pathways to water-based green chemistry approaches in materials science and nanotechnology.

Interparticle and Brownian forces controlling particle aggregation and rheology of silicate melts containing platinum-group element particles.

We study the rheology of silicate melts containing platinum-group element (PGE) particles. They exhibit a shear-thinning behaviour, an intense aggregation tendency, and an anomalously high apparent viscosity in the low shear rate limit, even at very low particle volume fraction. Using a compilation of published experimental data, we analyse these effects in three steps. Firstly, we observe that the viscosities of these suspensions are much higher than those of natural silicate crystal-bearing melts for low shear rate regimes. Secondly, we demonstrate that the viscosities at low shear rate limit cannot be estimated by classical rheological models but rather may be understood as the result of particle aggregation, trapping dead fluid, and thereby increasing the effective particle volume fraction. Finally, we scale the critical shear rates for shear-thinning using a Peclet number analysis-invoking a competition between random thermal particle motion and hydrodynamic shearing motion-and, using an empirical extension, we additionally account for the particle-particle interaction energetics. We propose a framework in which the rheology of this family of particle-bearing melts can be predicted, and demonstrate that at low Peclet numbers, PGE-bearing particle aggregation is driven by interparticle forces and Brownian motion.

Revealing the Physicochemical Basis of Organic Solid-Solid Wetting Deposition: Casimir-like Forces, Hydrophobic Collapse, and the Role of the Zeta Potential.

Supramolecular self-assembly at the solid-solid interface enables the deposition and monolayer formation of insoluble organic semiconductors under ambient conditions. The underlying process, termed as the organic solid-solid wetting deposition (OSWD), generates two-dimensional adsorbates directly from dispersed three-dimensional organic crystals. This straightforward process has important implications in various fields of research and technology, such as in the domains of low-dimensional crystal engineering, the chemical doping and band gap engineering of graphene, and in the area of field-effect transistor fabrication. However, to date, lack of an in-depth understanding of the physicochemical basis of the OSWD prevented the identification of important parameters, essential to achieve a better control of the growth of monolayers and supramolecular assemblies with defined structures, sizes, and coverage areas. Here we propose a detailed model for the OSWD, derived from experimental and theoretical results that have been acquired by using the organic semiconductor quinacridone as an example system. The model reveals the vital role of the ζ potential and includes Casimir-like fluctuation-induced forces and the effect of dewetting in hydrophobic nanoconfinements. Based on our results, the OSWD of insoluble organic molecules can hence be applied to environmental friendly and low-cost dispersing agents, such as water. In addition, the model substantially enhances the ability to control the OSWD in terms of adsorbate structure and substrate coverage.

Quantum Tunnelling to the Origin and Evolution of Life.

Quantum tunnelling is a phenomenon which becomes relevant at the nanoscale and below. It is a paradox from the classical point of view as it enables elementary particles and atoms to permeate an energetic barrier without the need for sufficient energy to overcome it. Tunnelling might seem to be an exotic process only important for special physical effects and applications such as the Tunnel Diode, Scanning Tunnelling Microscopy (electron tunnelling) or Near-field Optical Microscopy operating in photon tunnelling mode. However, this review demonstrates that tunnelling can do far more, being of vital importance for life: physical and chemical processes which are crucial in theories about the origin and evolution of life can be traced directly back to the effects of quantum tunnelling. These processes include the chemical evolution in stellar interiors and within the cold interstellar medium, prebiotic chemistry in the atmosphere and subsurface of planetary bodies, planetary habitability via insolation and geothermal heat as well as the function of biomolecular nanomachines. This review shows that quantum tunnelling has many highly important implications to the field of molecular and biological evolution, prebiotic chemistry and astrobiology.

Supramolecular self-assembly initiated by solid-solid wetting.

We present a preparation method for self-assembled supra-molecular monolayers of unsubstituted organic semiconductors and pigments on a solid substrate, applicable under ambient conditions. The deposition is based on a solid-solid wetting phenomenon, whereas the subsequent layer growth proceeds according to standard models. Molecular adsorption results from direct contact of the compound in a nanocrystalline state with the solid surface. Based on complementary force field calculations, we propose that molecules disintegrate from the crystalline state and adsorb on the surface because of a gain in binding energy. The preparation method is exemplified by means of a linear hydrogen-bonded system, namely quinacridone (QAC) on graphite. In addition, the chosen system allows us to actively guide the self-assembly after deliberate removal of molecules from a predefined area.