Spatial dissipative structures formed by spontaneous molecular aggregation at interfaces

Interfacial processes as well as formation of dissipative structures have been suggested to play a key role in early pre-biotic evolutionary stages, mainly due to the ability of such processes to induce aggregation and spatial structuring. In this context we would like to draw attention to our recent findings regarding a remarkably wide collection of interfacial chemical reactions which form dissipative spatial structures. Three types of interfacial processes were found to yield this phenomenon: photochemical oxidations at liquid/air and liquid/liquid interfaces; gas/solution reactions; and reactions at membrane surfaces. The phenomenon we describe is the first major example of a network of chemical reactions that develop into macroscopic far-from-equilibrium concentration patterns.     

Dissipative structures and amplification of enantiomeric excess (an experimental point of view)

Various mathematical models have been proposed to account for the origin of chiral molecules in biological systems. Most of these models invoke non-linear phenomena, and are based on the general concept of dissipative structures. These theoretical models define the fundamental criteria which must be obeyed by the experimental systems that we have investigated. Our initial approach to this problem was an extensive search of the literature data in order to select a few systems or experimental situations which would satisfy the criteria defined by the theoretical models. For these reasons, we carried out a study of the possibility of stereospecific autocatalysis in the asymmetric polymerisation of benzofuran. Similarly, the formation of spatial dissipative structures by coupling of a transport process with an interfacial reaction was investigated as a simple experimental example of symmetry breaking.     

The effect of electric field on the spatial-time patterns in the reaction-diffusion system

A model of electrodiffusion processes in the vicinity of cell membrane was developed. The model takes into account chemical reactions, Coulomb interactions between charged particles and the effect of external electric field. It was concluded that the applied electric field can change the characteristics of space-time patterns in the system. Dissipative structures slowly move and this is accompanied by a change in the number of structure elements. The characteristic equation includes odd powers of the wavenumber, which can lead to the appearance of soliton-like structures. The dissipative structures can appear not only due to the Turing diffusion instability but due to the disperse instability under electric field the applied.     

Use of image analysis to understand enzyme stability in an aerated stirred reactor

Efficient regeneration of NAD(P)⁺ cofactors is essential for large-scale application of alcohol dehydrogenases due to the high cost and chemical instability of these cofactors. NAD(P)⁺ can be regenerated effectively using NAD(P)H oxidases (NOXs) that require molecular oxygen as a cosubstrate. In large-scale biocatalytic processes, agitation and aeration are needed for sufficient oxygen transfer into the liquid phase, both of which have been shown to significantly increase the rate of enzyme deactivation. As such, the aim of this study was to identify the existence of a correlation between enzyme stability and gas–liquid interfacial area inside the bioreactor. This was done by measuring gas–liquid interfacial areas inside an aerated stirred reactor, using an in situ optical probe, and simultaneously measuring the kinetic stability of NOXs. Following enzyme incubation at various power inputs and gas-phase compositions, the residual activity was assessed and video samples were analyzed through an image processing algorithm. Enzyme deactivation was found to be proportional to an increase in interfacial area up to a certain limit, where power input appears to have a higher impact. Furthermore, the presence of oxygen increased enzyme deactivation rates at low interfacial areas. The areas were validated with defined glass beads and found to be in the range of those in large-scale bioreactors. Finally, a correlation between the enzyme half-life and specific interfacial area was obtained. Therefore, we conclude that the method developed in this contribution can help to predict the behavior of biocatalyst stability under industrially relevant conditions, concerning specific gas–liquid interfacial areas.     

Are nanometric films of liquid undercooled interfacial water bio-relevant?

It is known that life processes below the melting point temperature can actively evolve and establish in micrometer-sized (and larger) veins and structures in ice and permafrost soil, filled with unfrozen water. Thermodynamic arguments and experimental results indicate the existence of much smaller nanometer-sized thin films of undercooled liquid interfacial (ULI) water on surfaces of micrometer sized and larger mineral particles and microbes in icy environments far below the melting point temperature. This liquid interfacial water can be described in terms of a freezing point depression, which is due to the interfacial pressure of van der Waals forces. The physics behind the possibly also life supporting capability of nanometric films of undercooled liquid interfacial water, which also can “mantle” the surfaces of the much larger and micrometer-sized microbes, is discussed. As described, biological processes do not necessarily have to proceed in the “bulk” of the thin interfacial water, as in “vinical” water and in the micrometer-sized veins e.g., but they can be supported or are even made possible already by covering thin mantles of liquid interfacial water. These can provide liquid water for metabolic processes and act as carrier for the necessary transport of nutrients and waste. ULI water supports two different and possibly biologically relevant transport processes: 2D molecular diffusion in the interfacial film, and flow-like due to regelation. ULI-water, which is “lost” by transport into microbes, e.g., will be refilled from the neighbouring ice. In this way, the nanometric liquid environment of microbes in ULI-water is comparable to that of microbes in bulk water. Another probably also biologically relevant property of ULI is, depending on the hydrophobic or hydrophilic character of the surfaces, that it is of lower density (LDL) or higher density (HDL) than bulk water.Furthermore, capillary effects and ions in ULI-water solutions can support, enhance, and stabilize the formation of layers of interfacial water. A more detailed future investigation of the possible support of life processes by nanometric ULI water in ice is a challenge to current cryomicrobiology. Related results of Rivkina et al. [22] indeed indicate that life processes can remain active at water contents corresponding to about or less than two monolayers of ULI water.     

Water: A medium where dissipative structures are produced by a coherent dynamics

The Belousov-Zhabotinsky phenomenon is analyzed in a framework where the dynamics of dissipative structures outlined by Prigogine is implemented through the collective dynamics produced in liquid water by Quantum Electrodynamics, which has received recently some experimental support. A mechanism allowing the appearance of self-produced oscillations is suggested.     

Critical periods as fundamental events in life

Development is not a continuous phenomenon. Rather, phenophases are interspaced with short critical periods. This phenomenon reflects an alternance between stabilization (during a phenophase) and dismantling (during a critical period) of a network of between-organ relationships generating the organism. Networks of relationships may be compared to dissipative systems in physics. In this context, a critical period represents a transient phase of isolation of the systems enabling its evolution towards equilibrium. As suggested here, this transition from dissipative to isolated system represents the source of newly emerging dissipative structures in which environmental or developmental perturbations are adaptively integrated. In contrast to non-living systems, an endogenous control of the transition towards critical period seems to exist during development. By extension to other scales of biological organization, it is suggested that the capacity to self-define its status (dissipative or close-to-equilibrium) represents the key property of living systems. This asks for a reconsideration of some basic notions about life, such as the role of genes in normal development, in physiological adaptation, and even in the emergence of evolutionary novelty.     

Dehydration of a polyether type extraction agent and of the corresponding K+ complex: insights into liquid-liquid extraction mechanisms by quantum chemical methods

In this paper we report a quantum chemical study performed at the B3LYP/6-311G++(d,p) level of theory on structural and energetic aspects of the sequential dehydration of a tetra-hydrated polyethylene-glycol type podand (1,2-bis-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-benzene, hereafter b33) and its complex with the K(+) cation. Thermodynamical parameters were determined by hessian quantum calculations performed using a self-consistent reaction field (SCRF) method, taking into account solvent (dichloromethane) effects. The results allowed the estimation of dehydration enthalpies, entropies and free energies for the hydrated free b33 podand and its corresponding K(+) cation complex in dichloromethane. The low absolute values found for the dehydration free energies as well as the structural features found for the optimized structures and the corresponding basis superposition calculated interaction energies, support the hypothesis of an interfacial complexation type mechanism governing the assisted extraction of K(+) from an aqueous toward an organic phase, in liquid/liquid extraction.     

Scale invariance of biosystems: From embryo to community

Phenomena having the property of a scale invariance (that is, maintaining invariable structure in certain range of scales) are typical for biosystems of different levels. In this review, main manifestations of the scale-invariant phenomena at different levels of biological organization (including ontogenetic aspects) are stated, and the reasons of such wide distribution of fractal structures in biology are discussed. Almost all biological systems can be described in terms of synergetics as open nonequilibrium systems that exist due to substance and energy flow passing through them. The phenomenon of self-organization is typical for such dissipative systems; maintenance of energy flow requires the existence of complex structures that emerge spontaneously in the presence of the appropriate gradient. Critical systems, which form as a results of their activity scale-invariant structures (that are a kind of distribution channels), are optimal relative to the efficiency of substance and energy distribution. Thus, scale invariance of biological phenomena is a natural consequence of their dissipative nature.     

In Situ Transmission Electron Microscopy on Energy‐Related Catalysis

Energy‐related catalytic reactions have been extensively investigated in past years in order to efficiently utilize clean and environmentally benign energy sources. In these systems, the catalysts and the catalyst/active medium interfaces play a crucial role in determining their performance. Thus, understanding the physical and chemical properties of catalysts during reactions is of importance to provide fundamental insights for designing the devices. Transmission electron microscopy can provide tremendous information regarding materials' morphology, microstructure, and chemical properties at nanoscales. With in situ electron microscopy, dynamic processes of catalytic reactions in both gas and liquid environments have been investigated in real time. In this paper, the recent research progress of in situ and operando electron microscopy techniques are introduced with the representative works in energy‐related reactions, including electrochemical catalysis in liquid media and heterogeneous catalysis in gas media. The uniqueness of the specific electron microscopy methods and scientific merits of each work are highlighted. Finally, outlooks on emerging research opportunities are discussed.     

Biogenic Isoprene (A Review)

Biogenic isoprene was discovered in the mid-1950s as a component of volatile substances emitted from leaves. In plant species emitting isoprene under illumination, this process is closely related to photosynthesis. Thus, a photobiological phenomenon termed isoprene effect or isoprene emission (IE) was discovered. Subsequent studies showed that leaves are capable of releasing isoprene also in darkness, though at a rate two orders of magnitude lower than that in illuminated leaves. It is presently known that the isoprene is emitted not by all plant species from various taxonomic groups, whereas the dark release of isoprene occurs in cells of all living organisms. This review presents a brief historical account of studies dealt with IE. A special emphasis is placed on the roles of light as an energy source and of CO₂ as a carbon source; these factors create the energy–metabolite flow that runs through the green photosynthesizing cell. The data available suggest that IE can be considered as a manifestation of excretory function of the leaf. An attempt is made to describe IE from the standpoint of thermodynamics of irreversible processes. It is shown that the cell represents a dissipative structure whose organization and stability is provided by irreversible processes running far from equilibrium. General view on isoprene emission is that it results from regulated conversions of carbon and free energy in a series of photosynthetic reactions under stressful conditions caused by CO₂ deficit inside illuminated autotrophic cells. This stress generates the energy overflow, far in excess of the energy-consuming capacity. The necessity of discharging this energy excess is dictated by the fact that the living cell is a dissipative structure.     

Environmental control and spatial structures in peatland vegetation

Question: What are the relative influences of environment and space in structuring the plant composition in a peatland complex? Location: Lakkasuo, southern boreal zone, Finland. Method: We used principal coordinates of neighbour matrices (PCNM) to model spatial structures in the plant composition of a peatland complex comprising ombrotrophic and minerotrophic, open and forested areas. We used redundancy analyses (RDA) and variation partitioning to assess the relative influences of chemical variables (peat and water characteristics), physical variables (hydrology, soil properties, shade), as well as broad‐scale (>350 m) and medium‐scale (100–350 m) spatial structures on vegetation assemblages. Results: We identified five different significant spatial patterns circumscribing (1) the minerotrophic–ombrotrophic gradient; (2) dry ombrotrophic and wet minerotrophic areas; (3) open and shaded areas; (4) dry open/shaded and wet patches within the ombrotrophic areas; and (5) dry open patches and dry forested patches. With spatial structures and environmental variables, we were able to model 30% of the variability in plant composition in the peatland complex, 13% of which was attributable to spatial structures alone. Conclusions: We demonstrated that in the peatland complex, the spatial dependence processes were more important at the broadest scale, and found that patterns at a medium scale might reflect finer‐scale patterns that were not investigated here. Spatial autocorrelation in vegetation composition in the peatland complex appeared to be driven by Sphagnum species. Our results emphasize that spatial modelling should be routinely implemented in studies looking at species composition, since they significantly increase the explained proportion of variance.     

Novel Combination of Atomic Force Microscopy and Epifluorescence Microscopy for Visualization of Leaching Bacteria on Pyrite

Bioleaching of metal sulfides is an interfacial process comprising the interactions of attached bacterial cells and bacterial extracellular polymeric substances with the surface of a mineral sulfide. Such processes and the associated biofilms can be investigated at high spatial resolution using atomic force microscopy (AFM). Therefore, we visualized biofilms of the meso-acidophilic leaching bacterium Acidithiobacillus ferrooxidans strain A2 on the metal sulfide pyrite with a newly developed combination of AFM with epifluorescence microscopy (EFM). This novel system allowed the imaging of the same sample location with both instruments. The pyrite sample, as fixed on a shuttle stage, was transferred between AFM and EFM devices. By staining the bacterial DNA with a specific fluorescence dye, bacterial cells were labeled and could easily be distinguished from other topographic features occurring in the AFM image. AFM scanning in liquid caused deformation and detachment of cells, but scanning in air had no effect on cell integrity. In summary, we successfully demonstrate that the new microscopic system was applicable for visualizing bioleaching samples. Moreover, the combination of AFM and EFM in general seems to be a powerful tool for investigations of biofilms on opaque materials and will help to advance our knowledge of biological interfacial processes. In principle, the shuttle stage can be transferred to additional instruments, and combinations of AFM and EFM with other surface-analyzing devices can be proposed.     

Structure for energy cycle: a unique status of the second law of thermodynamics for living systems

Distinguishing things from beings, or matters from lives, is a fundamental question. Extending E. Schr?dinger's neg-entropy and I. Prigogine's dissipative structure, we propose a chemical kinetic view that the earliest "live" process is embedded essentially in a special interaction between a pair of specific components under a particular, corresponding environmental conditions. The interaction exists as an inter-molecular-force-bond complex(IMFBC) that couples two separate chemical processes: one is the spontaneous formation of the IMFBC driven by a decrease of Gibbs free energy as a dissipative process; while the other is the disassembly of the IMFBC driven thermodynamically by free energy input from the environment. The two chemical processes coupled by the IMFBC originated independently and were considered non-living on Earth, but the IMFBC coupling of the two can be considered as the earliest form of metabolism: the first landmark on the path from things to a being. The dynamic formation and disassembly of the IMFBC, as a composite individual, follows a principle designated as "… structure for energy for structure for energy…", the cycle continues; and for short it will be referred to as "structure for energy cycle". With additional features derived from this starting point, the IMFBC-centered "live" process spontaneously evolved into more complex living organisms with the characteristics currently known.     

Historic discovery of natural thermodynamic cause of cancer

The essence of life is best manifested in cell, which, when brought to the edge of its existence in the actual environment may and sometimes must self-organise into an entirely different cell (neoplasm), but it must enhance dissipation of matter and energy in its closest environment. This phenomenon has been described before as self-organisation of dissipative structures in physics, chemistry and even sociology. Each neoplastic cell is such a dissipative system - with its clonal growth, the cell causes increasing disorganisation of the body, in consequence leading to neoplastic disease. The only adequate cause of formation of neoplasms is an internal dissipathogenic cellular state, which is clinically identify as preneoplastic ones at the level of morphology or molecular biology but also biophysics. Two general directions for therapy of neoplastic diseases arise from the thermodynamic essence of neogenesis: the direct one - targeting neoplasms, and the indirect one - leading to normalisation or sufficient alteration of their environment. The greatest disappointment in the fight against neoplasm was the discovery of its thermodynamic cause in a natural self-organisation of biological dissipative structures. It is this dissipation that causes the signs and symptoms of neoplastic diseases ending with destruction of the body if the treatment comes too late and/or is insufficient, limited only to removal of neoplastic lesions without the always necessary elimination and/or prevention of preneoplastic (dissipathogenic) states.     

Structural studies on photosystem II of cyanobacteria

Photosynthesis is one of the most important chemical processes in the biosphere responsible for the maintenance of life on Earth. Light energy is converted into energy of chemical bonds in photoreaction centers, which, in particular, include photosystem II (PS II). PS II is a multisubunit pigment-protein complex located in the thylakoid membrane of cyanobacteria, algae and plants. PS II realizes the first stage of solar energy conversion that results in decomposition of water to molecular oxygen, protons, and bound electrons via a series of consecutive reactions. During recent years, considerable progress has been achieved in determination of the spatial structures of PS II from various cyanobacteria. In the present review, we outline the current state of crystallographic studies on PS II.     

Extraction of volatile fatty acids from diluted aqueous solution using a supported liquid membrane

Experimental and analytical studies on the extraction of volatile fatty acids (VFAs) from an aqueous solution using a supported liquid membrane (SLM) were carried out. Teflon and 20% (w/w) tri-n-octyl phosphine oxide (TOPO) in kerosene were used as the supporting membrane and liquid, respectively. The extraction rate of VFAs transferred from the source across the SLM to the sink was measured. It was observed that only undissociated forms of VFAs can penetrate into the SLM and that the complex formation between TOPO and VFA (1/1 molar ratio) inside the membrane enhanced the transfer rate of VFA across the membrane. This phenomenon was explained by mathematical models based on mass transfer and the chemical reactions occurring inside the membrane, suggesting that diffusion of the VFA-TOPO complex inside the membrane may be the rate-limiting step in this experiment.     

Simulation of chemical oscillations in membranes

A computer simulation model has been developed to follow chemical oscillations in a membrane for immobilized enzyme systems. It is a discrete particle type model which follows the spatial and temporal fluctuations of the concentrations in a reaction involving two substrates. The parameters can be readily varied to allow dissipative structures to result from the sustained nonlinear reaction kinetics and to determine which parameters cause damping of the oscillations. The nature of the diffusion mechanism allows extension to more than one dimension.     

Nanoporous Hybrid Electrolytes for High‐Energy Batteries Based on Reactive Metal Anodes

Successful strategies for stabilizing electrodeposition of reactive metals, including lithium, sodium, and aluminum are a requirement for safe, high‐energy electrochemical storage technologies that utilize these metals as anodes. Unstable deposition produces high‐surface area dendritic structures at the anode/electrolyte interface, which causes premature cell failure by complex physical and chemical processes that have presented formidable barriers to progress. Here, it is reported that hybrid electrolytes created by infusing conventional liquid electrolytes into nanoporous membranes provide exceptional ability to stabilize Li. Electrochemical cells based on γ‐Al₂O₃ ceramics with pore diameters below a cut‐off value above 200 nm exhibit long‐term stability even at a current density of 3 mA cm^?2. The effect is not limited to ceramics; similar large enhancements in stability are observed for polypropylene membranes with less monodisperse pores below 450 nm. These findings are critically assessed using theories for ion rectification and electrodeposition reactions in porous solids and show that the source of stable electrodeposition in nanoporous electrolytes is fundamental.