Dynamic bounds for power and efficiency of non-ideal energy converters under nonlinear transfer laws

We present a thermodynamic approach to simulation and modeling of nonlinear energy converters, in particular radiation engines. Novel results are obtained especially for dynamical engines when the temperature of the propelling medium decreases in time due to a continual decrease of the medium's internal energy caused by the power production. Basic thermodynamic principles determine the converter's efficiency and work limits in terms of the entropy production. The real work is a cumulative effect obtained in a system of a resource fluid, a sequence of engines, and an infinite bath. Nonlinear modeling involves dynamic optimization in which the classical expression for efficiency at maximum power is generalized to endoirreversible machines and nonlinear transfer laws. The primary result is a finite-rate generalization of the classical, reversible work potential (exergy). The generalized work function depends on thermal coordinates and a dissipation index, h, i.e. a Hamiltonian of the minimum entropy production problem. This generalized work function implies stronger bounds on work delivered or supplied than the reversible work potential. The role of the nonlinear analyses and dynamic optimization is shown especially for radiation engines. As an example of the kinetic work limit, generalized exergy of radiation fluid is estimated in terms of finite rates, quantified by the Hamiltonian h.     

Mercury emissions to the atmosphere from anthropogenic sources in Europe in 2000 and their scenarios until 2020

The paper reviews the current state of knowledge regarding European emissions of mercury and presents estimates of European emissions of mercury to the atmosphere from anthropogenic sources for the year 2000. This information was then used as a basis for Hg emission scenario development until the year 2020. Combustion of coal in power plants and residential heat furnaces generates about half of the European emissions being 239 tonnes. The coal combustion is followed by the production of caustic soda with the use of the Hg cell process (17%). Major points of mercury emission generation in the mercury cell process include: by-product hydrogen stream, end box ventilation air, and cell room ventilation air. This technology is now being changed to other caustic soda production technologies and further reduction of Hg emissions is expected in this connection. The third category on the list of the largest Hg emitters in Europe is cement production (about 13%). The largest emissions were estimated for Russia (the European part of the country), contributing with about 27% to the European emissions, followed by Poland, Germany, Spain, Ukraine, France, Italy and the United Kingdom. Most of these countries use coal as a major source of energy in order to meet the electricity and heat demands. In general, countries in the Central and Eastern Europe generated the main part of the European emissions in 2000. Emission reductions between 20% and 80% of the 2000 emission amounts can be obtained by the year 2020, as estimated by various scenarios.     

The effect of the framework structure on the chemical properties of the vanadium oxide species incorporated within zeolites

V-silicalite catalysts (VS-1 and VS-2) prepared by hydrothermal synthesis have been studied by ESR, XAFS (XANES and EXAFS) and photoluminescence spectroscopy. The in situ characterization of these V-silicalites shows that vanadium is present within the zeolitic framework as a highly dispersed tetrahedrally coordinated V-oxides, VO₄ unit, having a short V=O bond length. Photoluminescence spectroscopy in static and dynamic mode, as well as XAFS studies allow to detect in the V-silicalites different V species than that present in V-HMS or V/SiO₂, in terms of V=O bond length, vibrational energy, bond angle and lifetime of the excited triplet state. It is suggested that the combined contribution of the neighboring Si---OH group attached to the VO₄ unit and the zeolitic rigid framework structure of V-silicalites cause a more significant and pronounced effect on the chemical properties of the VO₄ unit than the flexible structure of V-HMS or V/SiO₂. Moreover, the dynamic quenching of the phosphorescence by the addition of reactant molecules such as NO or propane indicates that the V species in the excited triplet state can be expected to be the active sites for the photocatalytic reactions.     

De Novo Design of Polyhedral Protein Assemblies: Before and After the AI Revolution

Self-assembling polyhedral protein biomaterials have gained attention as engineering targets owing to their naturally evolved sophisticated functions, ranging from protecting macromolecules from the environment to spatially controlling biochemical reactions. Precise computational design of de novo protein polyhedra is possible through two main types of approaches: methods from first principles, using physical and geometrical rules, and more recent data-driven methods based on artificial intelligence (AI), including deep learning (DL). Here, we retrospect first principle- and AI-based approaches for designing finite polyhedral protein assemblies, as well as advances in the structure prediction of such assemblies. We further highlight the possible applications of these materials and explore how the presented approaches can be combined to overcome current challenges and to advance the design of functional protein-based biomaterials.     

Parallel kd-Tree Construction on the GPU with an Adaptive Split and Sort Strategy

We introduce a parallel kd-tree construction method for 3-dimensional points on a GPU which employs a sorting algorithm that maintains high parallelism throughout construction. Typically, large arrays in the upper levels of a kd-tree do not yield high performance when computing each node in one thread. Conversely, small arrays in the lower levels of the tree do not benefit from typical parallel sorts. To address these issues, the proposed sorting approach uses a modified parallel sort on the upper levels before switching to basic parallelization on the lower levels. Our work focuses on 3D point registration and our results indicate that a speed gain by a factor of 100 can be achieved in comparison to a naive parallel algorithm for a typical scene.     

Copying of dynamic structures in a pascal environment

Two problems involving the use of dynamic lists in Pascal are (1) the limited size of the heap and (2) the difficulty in creating copies of complex multi-linked structures. Both these problems can be solved by writing the appropriate segment of memory to a file on disk. The heap segment may then be released. To recover the structure during a later phase of processing, the contents of the file can be transferred back onto the heap. This paper presents an algorithm to implement this solution.     

In vivo model to study the biocompatibility of peritoneal dialysis solutions

This study was designed to analyze the complex morphologic and functional effects of dialysis solutions on peritoneum in a rat model on chronic peritoneal dialysis. Peritoneal catheters were inserted into 10 male, Wistar rats and the animals were dialyzed twice daily for 4 weeks with 4.25% Dianeal. During the study we observed two opposite effects: healing of the peritoneum after catheter implantation--decreased cell count in dialysate, decreased permeability of the peritoneum to glucose and total protein, increased volume of drained dialysate; and damage to the membrane due to its exposure to peritoneal dialysis solution--increased hyaluronic acid levels in dialysate, a tendency of the peritoneum to thicken when compared to non-dialyzed animals. Our rat model of CAPD may be used for quantitative and qualitative assessment of the effects of peritoneal dialysis solution on the peritoneum during chronic dialysis.     

Macromonomers by activated polymerization of oxiranes. Synthesis and polymerization

Macromonomers were obtained by cationic polymerization of propylene oxide and epichlorohydrin proceeding by the activated monomer mechanism with hydroxyethyl acrylate as initiator. Up to DP _n ～ 15 for propylene oxide and DP _n ～ 20 for epichlorohydrin, polymerization proceeds as a living process, giving with quantitative yields macromonomers with functionality equal to one, controlled molecular weight and narrow molecular weight distribution (M _wM _n<1.2) free of side products. In the higer molecular weight region, side reactions become increasingly noticeable. Propylene oxide macromonomers undergo radical homopolymerization. Homopolymerization of macromonomer with M _n = 8×10² gives graft copolymers with M _n up to 7.2×10³ in copolymerization with styrene, completely soluble graft copolymers with M _n ～ 2×10⁴ were obtained. Radical copolymerization of epichlorohydrin macromonomers with styrene gives initially soluble products with M _n ～ 6×10⁴ were obtained. Radical copolymerization of epichlorohydrin macromonomers with styrene gives initially soluble products with M_n～ 6×10⁴, which are converted in the later stages into insoluble gels, apparently due to the chain transfer to chloromethly groups of the polyepichlorohydrin chains.