A new invariant of stable equivalences of Morita type

It was proved in an earlier paper by the author that the Hochschild cohomology algebras of self-injective algebras are invariant under stable equivalences of Morita type. In this note we show that the orbit algebra of a self-injective algebra (considered as an --bimodule) is also invariant under stable equivalences of Morita type, where the orbit algebra is the algebra of all stable --bimodule morphisms from the non-negative Auslander-Reiten translations of to .

     

Effects of Metallic Silver Particles on Resonance Energy Transfer Between Fluorophores Bound to DNA

We examined the effects of metallic silver island films on resonance energy transfer (RET) between a donor and acceptor bound to double helical DNA. The donor was 4',6-diamidino-2-phenylindole (DAPI) and the acceptor was propidium iodide (PI). Proximity of the labeled DNA to the silver particles resulted in a dramatic increase in RET as seen from the emission spectra and the donor decay times. Proximity to silver particles results in an increase of the Förster distance from 35 Å an to an apparent value of 166 Å. These results suggest a new type of DNA hybridization assays based on RET over distances much longer than the free-space Forster distance.     

Plasmon-enhanced fluorescence near metallic nanostructures: biochemical applications

Amplification of fluorescence is a nanoscale phenomenon which is particularly pronounced in close proximity to metal nanostructures. Due to its sharp distance dependence, it is ideally suited to monitor biorecognition reactions. Using this effect we have been able to demonstrate ultrasensitive bioassays. Two types of metal nanostructures have been employed, nanometric silver islands deposited over an ultrathin metal mirror and silver fractal structures. For the first type, metal mirrors (aluminum, gold, or silver protected with a thin silica layer) were coated with SIFs and an immunoassay (model assay for rabbit IgG or myoglobin immunoassay) was performed on this surface using fluorescently labeled antibodies. Our results show that SIFs alone (on a glass surface not coated with metal) enhance the immunoassay signal approximately 3 to 10-fold. Using a metal mirror instead of glass as support for SIFs leads to up to 50-fold signal enhancement. The second type of metal nanostructures, silver fractals, were produced by electrochemical reduction of silver nitrate deposited on sapphire covered with a thin conductive film of indium tin oxide. These structures were used as a substrate for a model rabbit IgG bioassay. The fluorescence resulting from the binding of antibody labeled with Rhodamine was highly nonuniform with distinctive hot spots. These highly fluorescent regions were correlated with areas of higher Ag thickness and coverage. Such high values of fluorescence amplification in both types of nanostructures have been interpreted by using time-resolved fluorescence data and by considering the radiative properties of plasmons in the environments which promote plasmon coupling. PACS 87.64.Ni; 81.07.-b; 87.14.-g     

Advances in Surface-Enhanced Fluorescence

We report recent achievements in metal-enhanced fluorescence from our laboratory. Several fluorophore systems have been studied on metal particle-coated surfaces and in colloid suspensions. In particular, we describe a distance dependent enhancement on silver island films (SIFs), release of self-quenching of fluorescence near silver particles, and the applications of fluorescence enhancement near metalized surfaces to bioassays. We discuss a number of methods for various shaped silver particle deposition on surfaces.     

Metal-enhanced fluorescence: potential applications in HTS

Metallic surfaces and particles can have dramatic effects on fluorescence, including localized excitation, increased quantum yields, increased photostability and increased distances for resonance energy transfer (RET), and directional emission. While all these effects have not yet been realized in a single system, metal-enhanced fluorescence promises to provide the next generation of high sensitivity fluorescence assays for low copy number detection of biochemical species.     

Studies on the Adamantylation of N-Heterocycles and Nucleosides

Adamantylation of several N-heterocycles and of two ribonucleosides (uridine and toyocamycin) was studied. The exact substitution position by the adamantyl carbocation generated from adamantan-1-ol in CF₃COOH depends on the nature of the heterocyclic substrate. Thus, adamantylation of an additional exocyclic amino group (see Scheme 1), N-adamantylation of the heterocycle (Scheme 2), C-adamantylation of the heterocycle (Scheme 3), as well as the formation of heterocyclic N-adamantylcarboxamides via the Ritter reaction (Scheme 4) are possible. The structures of the reaction products were determined by means of elemental analysis and NMR, UV, and IR spectroscopy.     

On the scaling ranges of detrended fluctuation analysis for long-term memory correlated short series of data

We examine the scaling regime for the detrended fluctuation analysis (DFA)—the most popular method used to detect the presence of long-term memory in data and the fractal structure of time series. First, the scaling range for DFA is studied for uncorrelated data as a function of time series length L$L$ and the correlation coefficient of the linear regression R²$R^2$ at various confidence levels. Next, a similar analysis for artificial short series of data with long-term memory is performed. In both cases the scaling range λ$\lambda$ is found to change linearly—both with L$L$ and R²$R^2$. We show how this dependence can be generalized to a simple unified model describing the relation λ=λ(L,R²,H)$\lambda =\lambda (L,R^2,H)$ where H$H$ (1/2≤H≤1$1/2\le H\le 1$) stands for the Hurst exponent of the long range autocorrelated signal. Our findings should be useful in all applications of DFA technique, particularly for instantaneous (local) DFA where a huge number of short time series has to be analyzed at the same time, without possibility of checking the scaling range in each of them separately.     

On bimodules determining stable equivalences

In the paper one shows that for two indecomposable non-simple self-injective algebras over a field K we have that if the functor induces a stable equivalence then the bimodule _AN_B is contained in the frame of a connected component in the Auslander-Reiten quiver Γ_A⊗KB^op.     

Applications of the thermal analysis in preparation and investigation of the ceramic ferroics and multiferroics

Results of investigations on selected ceramic ferroics and multiferroics by TA method were presented. The authors of the work used the thermal analysis both to optimize a process of producing the ceramic ferroics and multiferroics and to examine phase transitions in that type of materials. In the case of synthesis of the ferroics and multiferroics as a result of sintering of a mixture of simple oxides, the TA method enables to determine the optimum synthesis temperature and temperatures of re-crystallization and disintegration of compounds and solid solutions. In the case of the sol–gel method, temperatures of dehydratization, burning of an organic phase, and crystallization of an amorphous powder formed from the residual gel were determined by the TA method. The TA method was also used to control a process of compacting and sintering the powders at high temperatures (T _s > 1,200 K), thus in a process of ceramic specimen formation. During rapid phase transitions, the ferroelectric specimens of a first type emit (in the cooling process) or absorb (in the heating process) so called latent heat of the phase transitions. On the DTA courses, it may be manifested in a form of exo- or endothermic peaks in the Curie temperature area (T _C). The test materials included the ferroelectric ceramics of composition x/65/35 PLZT (ferroic for x < 9 at%) and mixed bismuth oxide layered perovskites (M-BOLP) of composition Bi₅TiNbWO₁₅ with <m> = 1.5 and the mutliferroic Pb(Fe_1−x Nb _x )O₃ ceramics (PFN) and Bi₅TiFeO₁₅ (BTF).