Quantifying the lateral lipid domain properties in erythrocyte ghost membranes using EPR-spectra decomposition

Using EPR spectroscopy a typical lateral domain structure was detected in the membranes of spin-labeled bovine erythrocyte ghosts. The spectral parameters were determined by decomposing the EPR spectrum into three spectral components and tuned by a hybrid-evolutionary-optimization method. In our experiments the lateral domain structure and its properties were influenced by the variation in the temperature and by the addition of n-butanol. The specific responses of the particular domain types were detected. For the most-ordered domain type a break was seen in the temperature dependence of its order parameter, while the order parameters of the two less-ordered domain types exhibited a continuous decrease. Below the break-point temperature the alcohol-induced membrane fluidity variation is mainly a consequence of the change in the proportions of the least- and the most-ordered domain type and not the change of the domain-type ordering or dynamics (with n-butanol concentration). On the other hand, the fluidity variation above the break-point temperature arises from both types of changes. Interestingly, the proportion of the domain type that has its order parameter between that of the least- and the most-ordered domain type remains almost constant with concentration as well as with temperature, which implies its stability. Such characterization of the lateral membrane domain structure could be beneficial when considering the lipid-protein interactions, because it can be assumed that the activity of the membrane-bound enzyme depends on the properties of the particular domain type.     

Bifurcation of periodic solutions to variational inequalities in R κ based on Alexander-Yorke theorem

Variational inequalities are studied, where K is a closed convex cone in , 3, B is a × matrix, G is a small perturbation, a real parameter. The assumptions guaranteeing a Hopf bifurcation at some ₀ for the corresponding equation are considered and it is proved that then, in some situations, also a bifurcation of periodic solutions to our inequality occurs at some _{I 0}. Bifurcating solutions are obtained by the limiting process along branches of solutions to penalty problems starting at ₀ constructed on the basis of the Alexander-Yorke theorem as global bifurcation branches of a certain enlarged system.     

Next nearest neighbor effect in chromite

In this paper the Mossbauer spectra of a chromite at 140K 200K and 298K were measured. Next nearest neighbor effects were used to explain the spectra of the chromite, and multiple doublets of Fe²⁺ ions on the A sites were caused by the different cation combinations on 12 next nearest neighbor B sites. The quandrupole splitting of each of mult iple Fe²⁺ doublets decreases with increasing temperature.     

Ion exchangers containing phosphorus in their functional group

Summary Uranium or thorium separations from a number of various ions were studied by means of cation exchangers containing phosphorus in their functional group. These ion exchangers adsorb selectively only UO₂ ²⁺ or Th⁴⁺ ions from the mixture studied in a medium of >0.4 N nitric or hydrochloric acid. Several di- and trivalent cations are not sorbed under these conditions. In the absence of UO₂ ²⁺ and Th⁴⁺ ions, Me²⁺ may be more easily separated quantitatively from Me³⁺ in 0.2 N nitric or hydrochloric acid than with cation exchangers containing the -SO₃H group.

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Zusammenfassung Die quantitative Trennung von UO₂ ²⁺ oder Th⁴⁺ von einer Reihe anderer Ionen wurde mit Hilfe phosphorhaltiger Kationenaustauscher untersucht. Diese Ionenaustauscher sorbieren selektiv nur UO₂ ²⁺ oder Th⁴⁺-Ionen aus einem Medium von >0,4 N HNO₃ oder HCl. Eine Reihe verschiedener zwei- und dreiwertiger Kationen wird unter diesen Bedingungen nicht sortiert. Bei Abwesenheit von UO₂ ²⁺- und Th⁴⁺-Ionen kann man Me²⁺ in 0,2 N HNO₃- oder HCl-Lösung quantitativ von Me³⁺ trennen, und zwar leichter als mit -SO₃H-haltigen Austauschern.

     

Coulometrische permanganatometrische bestimmung von wasserstoffperoxyd

A method has been developed for the quantitative coulometric permanganatometric micro-determination of hydrogen peroxide. The end-point is ascertained by the colour changes of the indicators ferroin, and nitro-ferroin respectively     

Algorithm for coding DNA sequences into "spectrum-like" and "zigzag" representations

An algorithm for encoding long strings of building blocks, like 4 DNA bases (adenine-A, cytosine-C, thymine-T, and guanidine-G), 20 natural amino acids (from Alanine Ala to Valine-Val, plus the stop triplet), or all 64 possible base triplets (from AAA to TTT), into "zigzag" or "spectrum-like" representations is suggested. The new encoding scheme can be derived in the 3-, 2-, or 1-dimensional form depending on the user's wishes. The only information, besides the string for which the "spectrum-like" representation is sought, is the initial positioning of the complete set of units from which the string is composed, i.e., four positions for A, C, G, and T, or 20 positions for natural amino acids plus stop, etc. This initial positioning can be initialized in either the 3-, 2-, or 1-D form. As an illustration of the suggested encoding scheme of the visual and chemometric comparison of the first 10 exon strings of the beta globin gene of 10 different species, each string consisting of about 100 basic amino acids long is shown.     

Shedding light on the structure of a photoinduced transient excimer by time-resolved diffraction

Time-resolved single-crystal diffraction performed with synchrotron radiation shows that the 53(1) micros phosphorescent state, generated in the crystalline phase of trimeric {[3,5-(CF3)(2)Pyrazolate]Cu}(3) molecules by exposure to 355 nm of light at 17 K, is due to the formation of an excimer rather than the shortening of the intramolecular Cu...Cu distances within the trimeric units, or the formation of a continuous chain of interacting molecules. One of the intermolecular Cu...Cu distances contracts by 0.56 Angstroms from 4.018(1) to 3.46(1) Angstroms;, whereas the interplanar spacing of the trimers is reduced by 0.65 Angstroms; from 3.952(1) to 3.33(1) Angstroms. Density-functional theory calculations support the formation of a Cu...Cu bond through the intermetallic transfer of a Cu 3d electron to a molecular orbital with a large 4p contribution on the reacting Cu atoms.     

Potential formation in a bounded two-electron temperature plasma system with floating collector that emits electrons

Formation of the plasma potential in a plasma that contains energetic electrons and is bounded by a floating collector that emits electrons is studied theoretically. The problem is treated by a static. kinetic plasma-sheath model of Schwager and Birdsall [Phys. Fluids B2 (1990) 1057], which we have extended in order to include additional energetic electron population. The distribution of these electrons is assumed to be a high-temperature Maxwellian. They are called hot electrons. In the paper we study effects of the density and temperature of the hot electrons on the formation of the plasma potential. The model shows that for certain densities and temperatures of the hot electron population plasmas with two different plasma potentials can coexist in the system. These two plasmas are separated spatially by a double layer. For the case when there is no emission of electrons from the collector, results of the model are compared with computer simulation and very good agreement between the model and the simulation is found. The simulation also confirms existence of two plasmas with two different potentials separated by a double layer.