Zoltán Németh

Porous Silicon/Photosynthetic Reaction Center Hybrid Nanostructure

The purified photosynthetic reaction center protein (RC) from Rhodobacter sphaeroides R-26 purple bacteria was bound to porous silicon microcavities (PSiMc) either through silane-glutaraldehyde (GTA) chemistry or via a noncovalent peptide cross-linker. The characteristic resonance mode in the microcavity reflectivity spectrum red shifted by several nanometers upon RC binding, indicating the protein infiltration into the porous silicon (PSi) photonic structure. Flash photolysis experiments confirmed the photochemical activity of RC after its binding to the solid substrate. The kinetic components of the intraprotein charge recombination were considerably faster (τ(fast) = 14 (±9) ms, τ(slow) = 230 (±28) ms with the RC bound through the GTA cross-linker and only τ(fast) = 27 (±3) ms through peptide coating) than in solution (τ(fast) = 120 (±3) ms, τ(slow) = 1387 (±2) ms), indicating the effect of the PSi surface on the light-induced electron transfer in the protein. The PSi/RC complex was found to oxidize the externally added electron donor, mammalian cytochrome c, and the cytochrome oxidation was blocked by the competitive RC inhibitor, terbutryne. This fact indicates that the specific surface binding sites on the PSi-bound RC are still accessible to external cofactors and an electronic interaction with redox components in the aqueous environment is possible. This new type of biophotonic material is considered to be an excellent model for new generation applications at the interface of silicon-based electronics and biological redox systems designed by nature.

THE NUMBER OF TRIANGULAR ISLANDS ON A TRIANGULAR GRID

The aim of the present paper is to carry on the research of Czédli in determining the maximum number of rectangular islands on a rectangular grid. We estimate the maximum of the number of triangular islands on a triangular grid.

Light-harvesting bio-nanomaterial using porous silicon and photosynthetic reaction center

Porous silicon microcavity (PSiMc) structures were used to immobilize the photosynthetic reaction center (RC) purified from the purple bacterium Rhodobacter sphaeroides R-26. Two different binding methods were compared by specular reflectance measurements. Structural characterization of PSiMc was performed by scanning electron microscopy and atomic force microscopy. The activity of the immobilized RC was checked by measuring the visible absorption spectra of the externally added electron donor, mammalian cytochrome c. PSi/RC complex was found to oxidize the cytochrome c after every saturating Xe flash, indicating the accessibility of specific surface binding sites on the immobilized RC, for the external electron donor. This new type of bio-nanomaterial is considered as an excellent model for new generation applications of silicon-based electronics and biological redox systems.

Tauberian Conditions under Which Convergence of Integrals Follows from Summability (C, 1) over R+

AbstractGiven f ∈ Lloc1(R+), we define

Algebraic and graph-theoretic properties of infinite n-posets

s\left( t \right): = \int\limits_0^t {f\left( x \right)} {\text{ }}dx{\text{ and }}\sigma \left( t \right):\frac{1}{t}{\text{ }}\int\limits_0^t {s\left( u \right)} {\text{ }}du{\text{ for }}t >0

Copper-Coated Cellulose-Based Water Filters for Virus Retention

Our permanent assumption is that σ(t) → A as t → ∞, where A is a finite number.First, we consider real-valued functions, and prove that s(t) → A as t → ∞ if and only if two one-sided Tauberian conditions are satisfied. In particular, these two conditions are satisfied if s(t) is slowly decreasing (or increasing) in the sense of R. Schmidt; in particular, if f(x) obeys a Landau type one-sided Tauberian condition.Second, we extend these results for complex-valued functions by giving a two-sided Tauberian condition, being necessary and sufficient in order that σ(t) → A imply s(t) → A as t → ∞. In particular, this condition is satisfied if s(t) is slowly oscillating; in particular if f(x) obeys a Landau type two-sided Tauberian condition.

P1.7.10 Methanol and ethanol vapor sensitivity of MWCNT/SnO2/Ru nanocomposite structures

AbstractA simple, reproducible, one-step electrochemical synthesis of vertically aligned ZnO nanorod electrode has been worked out. The gradual decrease in the photoelectrochemical performance of the hexagonal ZnO nanorod electrode indicated rapid photodegradation. In order to prevent the n-type semiconductor from photocorrosion, different conducting polymers were deposited on it. Composition and morphology of the hybrids were controlled by carefully changing the electropolymerization parameter (e.g., deposition charge) for the various N or S containing heterocycles. Electrochemical measurements proved that the redox activity of these covering polymer layers was preserved in the hybrid configuration. Photoelectrochemical activity of the polymer-covered ZnO nanorods was masked by thicker layers. Thin films however, successfully inhibited the photocorrosion of ZnO while preserving their photoactivity. Effective protection was evidenced using poly(3,4-ethylenedioxypyrrole) (PEDOP) in comparison with polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT). Graphical Abstractᅟ

On the order of magnitude of Fourier coefficients with respect to uniformly bounded orthonormal systems

A Σ -labeled n -poset is an (at most) countable set, labeled in the set Σ , equipped with n partial orders. The collection of all Σ -labeled n -posets is naturally equipped with n binary product operations and n ω -ary product operations. Moreover, the ω -ary product operations give rise to n ω -power operations. We show that those Σ -labeled n -posets that can be generated from the singletons by the binary and ω -ary product operations form the free algebra on Σ in a variety axiomatizable by an infinite collection of simple equations. When n = 1 , this variety coincides with the class of ω -semigroups of Perrin and Pin. Moreover, we show that those Σ -labeled n -posets that can be generated from the singletons by the binary product operations and the ω -power operations form the free algebra on Σ in a related variety that generalizes Wilkes algebras. We also give graph-theoretic characterizations of those n -posets contained in the above free algebras. Our results serve as a preliminary study to a development of a theory of higher dimensional automata and languages on infinitary associative structures.