Fuzzy control of the production environment process parameters

The fuzzy control process for support of given microclimatic production environment process parameters with loss of one from values, regulating regime of process was shown. The structural schematic decisions with algorithm of functioning and oriented to existing apparatus (means of realization) was presented

Interplay of local hydrogen-bonding and long-ranged dipolar forces in simulations of confined water

Spherical truncations of Coulomb interactions in standard models for water permit efficient molecular simulations and can give remarkably accurate results for the structure of the uniform liquid. However truncations are known to produce significant errors in nonuniform systems, particularly for electrostatic properties. Local molecular field (LMF) theory corrects such truncations by use of an effective or restructured electrostatic potential that accounts for effects of the remaining long-ranged interactions through a density-weighted mean field average and satisfies a modified Poisson's equation defined with a Gaussian-smoothed charge density. We apply LMF theory to three simple molecular systems that exhibit different aspects of the failure of a naive application of spherical truncations -- water confined between hydrophobic walls, water confined between atomically-corrugated hydrophilic walls, and water confined between hydrophobic walls with an applied electric field. Spherical truncations of 1/r fail spectacularly for the final system in particular, and LMF theory corrects the failings for all three. Further, LMF theory provides a more intuitive way to understand the balance between local hydrogen bonding and longer-ranged electrostatics in molecular simulations involving water.Comment: Submitted to PNA

Szerkezeti változások monomerektől a biopolimerek felé = Structural changes from monomers to biopolymers

Kutatásaink fő célja kémiai-biológiai frontvonalbeli jelentőségű peptidek és szénhidrátok szerkezeti jellemzőinek felderítése volt, fokozott figyelemmel a szerkezeti jellemzők alakulására a biomolekulák méretének növekedésével. Homo-oligopeptidek kvantumkémiai vizsgálatával kimutattuk a távolható kölcsönhatások stabilizáló szerepét és mértékét a másodlagos szerkezetekben, és meghatároztuk azokat a geometriai paramétereket, amelyek ezen kölcsönhatások jelzésére/mérésére alkalmasak. A prionfehérje 115-122 szegmensének konformációs analízisével igazoltuk ezen szegmens hajlamát béta-redős szerkezet kialakítására vizes oldatban. Felderítettük a hialuronan kisebb szacharid egységeinek (D-glükuronsav, N-acetil-D-glükózamin és a belőlük származtatható diszacharidok) konformációs tulajdonságait a gázfázis és a vizes oldat kvantumkémiai modellezésével. Kísérleti és elméleti módszerek kombinált alkalmazásával elvégeztük a fenti monoszacharidok teljes rezgési analízisét szilárd fázisú FT-IR spektrumaik alapján. Részben analóg módon, de a kifagyasztott gázfázisról készített FT-IR spektrumok alapján határoztuk meg a glükóz teljes rezgési erőterét és a gázfázisban uralkodó konformációs egyensúly jellemzőit. Kisebb biológiai jelentőséggel bíró vegyületeken végzett szerkezeti vizsgálatokkal együtt a pályázat anyagi támogatásával 19 tudományos közlemény és 2 könyvfejezet készült. | The main goal of our project was the determination of structural characteristics of peptides and carbohydrates of frontier chemical-biological importance. We paid particular attention to the variation of the structural properties with increasing model size. Our quantum chemical calculations on homooligopeptides showed the importance and magnitude of long-range interactions on the stabilization of the secondary structures and determined the geometrical parameters of marker character. On the basis of a conformational analysis of the 115-122 segment of prion protein we interpreted the propensity for beta-sheet formation of secondary structures in aqueous solutions. We elucidated the conformational properties of the building-blocks of hyaluronan (D-glucuronic acid, N-acetyl-D-glucosamine and disaccharides formed from them) by means of quantum chemical modeling of the gaseous phase and aqueous solution. We performed a complete vibrational analysis of the monosaccharides on the basis of their solid-phase FT-IR spectra jointly applying experimental and theoretical methods,. Using in part an analogous approach, we determined the full vibrational force field of glucose and the character of its gas-phase conformational equilibrium on the basis of FT-IR spectra of the frozen vapor,. These works augmented with structural studies of compounds of lesser biological importance resulted in 19 research papers and 2 book chapters with the financial support from the present OTKA grant

On "the complete basis set limit" and plane-wave methods in first-principles simulations of water

Water structure, measured by the height of the first peak in oxygen-oxygen radial distributions, is converged with respect to plane-wave basis energy cutoffs for ab initio molecular dynamics simulations, confirming the reliability of plane-wave methods.Comment: 9 pages, 3 figure

Water at an electrochemical interface - a simulation study

The results of molecular dynamics simulations of the properties of water in an aqueous ionic solution close to an interface with a model metallic electrode are described. In the simulations the electrode behaves as an ideally polarizable hydrophilic metal, supporting image charge interactions with charged species, and it is maintained at a constant electrical potential with respect to the solution so that the model is a textbook representation of an electrochemical interface through which no current is passing. We show how water is strongly attracted to and ordered at the electrode surface. This ordering is different to the structure that might be imagined from continuum models of electrode interfaces. Further, this ordering significantly affects the probability of ions reaching the surface. We describe the concomitant motion and configurations of the water and ions as functions of the electrode potential, and we analyze the length scales over which ionic atmospheres fluctuate. The statistics of these fluctuations depend upon surface structure and ionic strength. The fluctuations are large, sufficiently so that the mean ionic atmosphere is a poor descriptor of the aqueous environment near a metal surface. The importance of this finding for a description of electrochemical reactions is examined by calculating, directly from the simulation, Marcus free energy profiles for transfer of charge between the electrode and a redox species in the solution and comparing the results with the predictions of continuum theories. Significant departures from the electrochemical textbook descriptions of the phenomenon are found and their physical origins are characterized from the atomistic perspective of the simulations.Comment: 29 pages, 15 figure