Luminescence light collection technology in the aragonite of stone corals.

Stone corals do not use calcium carbonate in the form of calcite, which has a calculated energy gap of 3.93 eV, but in the form of aragonite, which has a calculated energy gap of 2.88 eV (here experimentally determined to amount to 2.46 eV) as a building material. This enables the coral to harvest blue light, which is penetrating and filtering deep into the surface water of the ocean. White luminescence, which is composed of different wave lengths, is generated, and then conducted and redistributed within the aragonite structure to be supplied to the symbiotic photosynthetic algae. This mechanism of light concentration and adaptation via the aragonite structure leads to a smaller amount of light-absorbing phosphorescent pigments being required for the symbionts to survive. The resulting advantages are a significantly smaller exposure to photo-degradation, less effort for chemical synthesis and higher efficiency for solar energy conversion. The mechanism of luminescence light collection in the aragonite network is discussed on the basis of spectroscopic measurements on thin coral slices and in context with its architecture and the coral's living activities. The relevance of the stone coral's fractal geometry, both for broadband solar light harvesting and luminescence light collection within non-imaging optics, is emphasized. It is proposed that synthetic aragonite should be developed as a solar energy material.

Nano-material aspects of shock absorption in bone joints.

This theoretical study is based on a nano-technological evaluation of the effect of pressure on the composite bone fine structure. It turned out, that the well known macroscopic mechano-elastic performance of bones in combination with muscles and tendons is just one functional aspect which is critically supported by additional micro- and nano- shock damping technology aimed at minimising local bone material damage within the joints and supporting spongy bone material. The identified mechanisms comprise essentially three phenomena localised within the three-dimensional spongy structure with channels and so called perforated flexible tensulae membranes of different dimensions intersecting and linking them. Kinetic energy of a mechanical shock may be dissipated within the solid-liquid composite bone structure into heat via the generation of quasi-chaotic hydromechanic micro-turbulence. It may generate electro-kinetic energy in terms of electric currents and potentials. And the resulting specific structural and surface electrochemical changes may induce the compressible intra-osseal liquid to build up pressure dependent free chemical energy. Innovative bone joint prostheses will have to consider and to be adapted to the nano-material aspects of shock absorption in the operated bones.

Photoelectrochemical power, chemical energy and catalytic activity for organic evolution on natural pyrite interfaces.

Natural pyrite (FeS2) has frequently been discussed as a material involved in CO2 fixation in presence of H2S and as a possible catalyst for the origin of life. A straightforward chemical fixation of carbon dioxide as proposed by Wächtershauser could not be verified from thermo-chemical equilibrium calculations by minimizing Gibb's Free Energy in the system C, O, H, S, Fe and appears unlikely due to the experimentally encountered large overpotentials involved in CO2 fixation. However, the hypothesis, by W. R. Edwards, that pyrite in shallow coastal waters may have been involved, can be sustained. In this case, daily available photoelectrochemical power from FeS2/Fe2+/3+ interfaces could have made the difference in combination with electrochemical processes, such as hydrogen insertion, and the solubilization of pyrite by the amino acid cysteine to yield dissolved chemical energy. Periodical changes in energy supply could also have entrained primitive self-organization processes for organic-biological evolution. Natural samples from thirteen ore deposits have been investigated photoelectrochemically. Efficient light-induced current generation has been found with several of these samples so that photoelectrochemical processes generated by pyrite have to be considered as naturally occurring phenomena, which could have been even more pronounced in oxygen deficient environments. Pyrite from the Murgul mine in Turkey of suboceanic volcanic origin was closer examined as a model system to understand the morphology and chemistry of pyrite photoactivity.

Patterns of periodic infrared light emission from the human body: a new diagnostic tool.

The human body emits infrared light with the periodicity of the heartbeat. The infrared thermal emission occurs in characteristic patterns which, after the heartbeat, migrate over the body. The images are obtained by using the electrocardiographic signal as a trigger to produce a thermal image which is subtracted from another one taken a well defined time later, before the next heart impulse. When these difference images are frequently repeated and averaged a heart pulse induced heat turnover is determined which has no relation to conventional heat images of the human body. Preliminary studies suggest that basically the heat turnover is seen in tissues where oxygen consumption leads to the turnover of chemical energy. When further developed, the proposed technique may provide a novel noninterfering and economically well affordable diagnostic tool for the examination of the external surface of the human body.

Electron transfer: classical approaches and new frontiers

Electron transfer, under conditions of weak interaction and a medium acting as a passive thermal bath, is very well understood. When electron transfer is accompanied by transient chemical bonding, such as in interfacial coordination electrochemical mechanisms, strong interaction and molecular selectivity are involved. These mechanisms, which take advantage of "passive self-organization," cannot yet be properly described theoretically, but they show substantial experimental promise for energy conversion and catalysis. The biggest challenge for the future, however, may be dynamic, self-organized electron transfer. As with other energy fluxes, a suitable positive feedback mechanism, through an active molecular environment, can lead to a (transient) decrease of entropy equivalent to an increase of molecular electronic order for the activated complex. A resulting substantial increase in the rate of electron transfer and the possibility of cooperative transfer of several electrons (without intermediates) can be deduced from phenomenological theory. The need to extend our present knowledge may be derived from the observation that chemical syntheses and fuel utilization in industry typically require high temperatures (where catalysis is less relevant), whereas corresponding processes in biological systems are catalyzed at environmental conditions. This article therefore focuses on interfacial or membrane-bound electron transfer and investigates an aspect that nature has developed to a high degree of perfection: self-organization.

Synergetic mechanisms in energy and signal transduction: photo oscillating proton transport in bacteriorhodopsin.

Receptor proteins, linked with G-proteins and effector proteins, which act in signal information and energy transduction are key elements in biochemical systems that dissipate energy and rely on maintenance of order. Until now they have not yet been considered as elements for synergetic mechanisms. This paper describes the synergetic mechanisms of the archaebacterial signal and energy receptor bacteriorhodopsin (bR), for which, recently, light induced oscillations have been experimentally demonstrated. A synergetic mechanisms for proton pumping by this protein is presented. An important precondition is the ability of the molecule to significantly reduce its entropy (i.e. to increase its order through export of entropy) during the photo cycle. This should be paralleled by a systematic and organized change of pK values along the proton transducting "channel". The interaction of occupied and vacant protonation sites at such energized amino acid chains gives rise to feedback loops leading to an autocatalytic mechanism of proton transfer which, in combination with nonlinearities at the membrane interfaces and a time delay during the proton back flux, provides a simplified mechanism for oscillative light induced proton pumping. The expected relevance of autocatalytic and synergetic processes as inbuilt mechanisms for energy conversion and signal processing and the maintenance of order is discussed.

Stimulated and co-operative electron transfer in energy conversion and catalysis.

A new mechanism of electron transfer, stimulated electron transfer, is postulated, in which an electronic feedback is drastically increasing both the rate of electron transfer and the propagation of free energy along electron transferring molecular pathways. In principle, the idea of pushing a system far from equilibrium to achieve a high reaction rate and co-operative phenomena is applied to molecular electron transfer. The effect is calculated from a semiclassical kinetic model of a chain redox reaction with autocatalytic feedback on individual rate constants, where the steps have subsequently been minimized to obtain a continuous electron transfer pathway with electronic feedback. The influence of inhomogeneities and asymmetries in the electron transfer path and of vectorial components (electrical field, gradient of redox potential) are discussed as well as the acceleration of individual and multiple electron transfer as a function of feedback. Examples of autocatalytic feedback are provided including mechanisms involving electron transfer proteins and multi-centre electron transfer catalysts. Such a phenomenon can be described for molecular and interfacial electron transfer in analogy to stimulated and coherent light emission. The results suggest that autocatalytic or stimulated electron transfer may be a key to the understanding of efficient electron transfer and co-operative multi-electron transfer catalysis in biology and a challenge for fuel production mechanisms in artificial photosynthesis and fuel cycles.

Novel technique for investigation and quantification of bacteriol leaching by Thiobacillus ferrooxidans.

A novel, efficient, and simple technique for the in situ study and quantification of the heterogeneous Bacteriol activity and the Bacteriol degradation of metal sulfides by Thiobacillus ferrooxidans is presented. It consists of exposing an ultrathin (300-2500 A) metal sulfide layer, FeS(2) in the experiments, to Thiobacillus f. grown in Touvinen media and visually following the Bacteriol attack and development of Bacteriol corrosion patterns under a light microscope. The uniform pyrite layer, partially transparent for visible light, permits the optical characterization of Bacteriol attack in remarkable detail. Several open or little understood questions concerning Bacteriol leaching, such as those on the kinetics of adhesion, the interfacial Bacteriol reproduction, the density of surface active bacteria, and the rate and morphology of sulfide degradation can also be studied. The degree of Bacteriol activity can be distinguished on the basis of development of variable sizes of spots and halos around Bacteriol cells produced by light passing through differently sized corrosion pits. The information obtained and identification of microorganisms has additionally been accentuated by immunofluorescence techniques (FA). It is concluded that the described method can be developed as a convenient testing and control technique for use in mine laboratories and bioleaching operations.

Bacterial leaching patterns on pyrite crystal surfaces.

Selected pyrite crystals were placed as a bacterial energy source into stationary cultures of Thiobacillus ferroxidans. Scanning electron microscope studies performed after a period of 2 years on these crystals revealed bacterial etching pits in characteristic patterns; they include pit arrangements in loose statistical disorder, in pairs, in clusters, and most remarkably in pearl-string-like chains. It has previously been confirmed that the chemical processes of bacterial leaching occur mainly in the region of contact between bacteria and the sulfide surface. The evidence presented in this experiment strongly suggests that the observed bacterial distributions are critically dependent on crystal structure and on deviations in the crystal order (fracture lines, dislocations) of the leachable substrate.