A dizinc complex for selective fluorescence sensing of uridine and uridine-containing dinucleotides

A dizinc complex with a polyamine macrocycle is able to selectively bind and sense uridine (U) as well as the uridine-containing ribodinucleotides U(3'-5')pU and U(3'-5')pA, thanks to an exciplex emission arising from a pi-stacked complex involving the dipyridine unit and Zn(II)-bound uridine moieties.     

Possible Wormhole Solutions in (4 + 1) Gravity

We extend previous analyses of soliton solutionsin (4 + 1) gravity to new ranges of their definingparameters. The geometry, as studied using invariants,has the topology of wormholes found in (3 + 1) gravity. In the induced-matter picture, thefluid does not satisfy the strong energy conditions, butits gravitational mass is positive. We infer thepossible existence of (4 + 1) which, compared to their (3 + 1) counterparts, are lessexotic.     

Structural study of hyaluronic acid oligomers and their complexes with copper in water by NMR and IR and molecular dynamics calculations

The hexasaccharide (trimer) and tetrasaccharide (dimer) oligomers of hyaluronic acid were investigated by ¹H and ¹³C high resolution Nuclear Magnetic Resonance. The dynamic behavior of the molecules and their complexation with copper(II) were analysed by ¹H NMR relaxation studies. A specific site for the complexation of the tetrasaccharide with Cu²⁺ was demonstrated by analysis of the paramagnetic effect of the metal on non-selective proton relaxation rates. A model for the complex involving two molecules of the tetrasaccharide is proposed.     

Solar modulation of cosmic deuteron fluxes in the PAMELA experiment

The preliminary results from measurements of deuteron fluxes in galactic cosmic rays (GCR) in the vicinity of the Earth in 2006–2009 are presented. The results are obtained by analyzing data from the PAMELA experiment aboard the Resurs DK-1 satellite. High-precision detection instruments provided an opportunity to identify GCR deuterons and measure their spectrum in the energy interval of 90–650MeV/nucleon. Spectra averaged over six-month intervals from the summer of 2006 to the summer of 2009 (the solar activity minimum) are presented. The influence of solar modulation on the observed spectrum is clearly seen in the results.     

Evaluation of different protocols for anatomical studies in Parmeliaceae (lichenized Ascomycota)

Anatomical information on most lichen species, including Parmeliaceae species, is scarce and superficial. This is partially due to the technical difficulties found during the preparation of samples and sections suitable for optical microscopy analysis. There is a lack of pictures of anatomical sections as well as detailed anatomical protocols related to the sample processing made by specialized plant anatomists in literature. This work aimed to look for a standardized histological technique and to develop a protocol for histological studies of foliose Parmeliaceae under light microscopy. Four common pantropical species of Parmeliaceae, abundant in the Brazilian cerrado vegetation, were processed in several ways in relation to fixing and inclusion media, sectioning thicknesses, and staining, including both fresh and 2-year-old herbarium specimens. The best technique found for anatomical studies of Parmeliaceae under light microscopy is represented by 2 or 3 microm thick sections of fresh or herbarium samples, desiccated and fixed in FAA 50, infiltrated and embedded in glycol-methacrylate resin (Leica), and stained by Toluidine Blue or Methylene Blue.     

Trapped Positrons and Electrons in the Inner Radiation Belt According to Data of the PAMELA Experiment

Measurements of secondary-electron and secondary-positron fluxes below the geomagnetic cutoff in near-Earth space were performed by means of the PAMELA magnetic spectrometer installed on board the Resurs-DK1 satellite launched on June 15, 2006, in an elliptical orbit of inclination 70° and altitude 350 to 600 km. This spectrometer permits measuring the fluxes of electrons and positrons over a wide energy range, as well as determining their spatial distributions to a precision of about 2°. A calculation of particle trajectories in the geomagnetic field makes it possible to separate electrons and positrons originating from cosmic-ray interactions in the Earth’s magnetosphere. The spatial distributions of quasitrapped, trapped, and short-lived albedo positrons and electrons of energy above 70 MeV in the radiation belt were analyzed. The ratio of the electron-to-positron fluxes and the energy spectra of the electrons and positrons in question are indicative of different productionmechanisms for stably trapped and quasitrapped secondary particles.     

Methods for Elemental Analysis of Size-Resolved PM Samples Collected on Aluminium Foils: Results of an Intercomparison Exercise

Aluminium is the most common substrate in studies using impactors for the measurement of the number or the weight of size-segregated atmospheric particulate matter (PM), as its characteristics perfectly fit impactor requirements. However, its use is not recommended by manufacturers when one of the purposes of the study is the determination of the metal content in the sample. The aim of this work was to develop an efficient analytical procedure for the removal and acid digestion of PM samples collected on aluminium foils by a cascade impactor to perform the determination of metals. The possibility of performing the trace metal analysis of PM samples collected using aluminium foils is of great importance, as it allows the determination of an accurate size distribution and the elemental composition of the PM collected on each impactor stage. Two procedures were optimised by using different digestion and analysis techniques. Both procedures were then applied to the two halves of several Dekati low-pressure impactor (DLPI) samples, and the results were critically compared. The two procedures proved to be effective in the determination of extremely low concentrations of a large suite of analytes in different size fractions of PM emitted by a brake system.     

Environmentally Sustainable Achiral and Chiral Chromatographic Analysis of Amino Acids in Food Supplements

Two LC methods were developed for the achiral and chiral reversed-phase (RP) analysis of an amino acid (AA) pool in a food supplement, in compliance with the main paradigms of Green Chromatography. A direct achiral ion-pairing RP-HPLC method was optimized under gradient conditions with a water-ethanol (EtOH) eluent containing heptafluorobutyric acid (0.1%, v/v), to quantify the eight essential AAs (Ile, Leu, Lys, Met, Phe, Thr, Trp, and Val) contained in the food supplement. Thus, the usually employed acetonitrile was profitably substituted with the less toxic and more benign EtOH. The method was validated for Leu and Phe. The chiral LC method performed with a teicoplanin chiral stationary phase was developed with a water-EtOH (60:40, v/v) eluent with 0.1%, v/v acetic acid. The enantioselective analysis was carried out without any prior derivatization step. Both developed methods performed highly for all eight AAs and revealed that: (i) the content of six out of eight AAs was consistent with the manufacturer declaration; (ii) only L-AAs were present. Furthermore, it was demonstrated that a two-dimensional achiral–chiral configuration is possible in practice, making it even more environmentally sustainable. A molecular modelling investigation revealed interesting insights into the enantiorecognition mechanism of Lys.     

Photoinduced Energy- and Electron-Transfer Processes in a Side-to-Face RuII-Porphyrin/Perylene-bisimide Array

A side-to-face array DPy-gPBI[Ru(4-tBuTPP)(CO)]₂, based on a “green” perylene bisimide chromophore sandwiched between two Ru^II-porphyrins, has been prepared by self-assembly. Its photophysical properties have been characterized in detail by a combination of steady-state and time-resolved techniques upon selective excitation of the two different components. Different photoinduced processes are observed as a function of the excitation wavelength. Electron transfer quenching is attained upon “red light” excitation of the perylene unit, whilst an energy transfer pathway is followed upon “green light” excitation of the metallo-porphyrin moiety. Regardless of the excitation wavelength efficient population of the triplet excited state of the perylene chromophore is achieved. The photophysical results are discussed within the framework of classical electron transfer theory and compared with those of a previously reported system.