Determination of the geographical origin of Brazilian wines by isotope and mineral analysis

In the present research, we studied wines from three different south Brazilian winemaking regions with the purpose of differentiating them by geographical origin of the grapes. Brazil's wide territory and climate diversity allow grape cultivation and winemaking in many regions of different and unique characteristics. The wine grape cultivation for winemaking concentrates in the South Region, mainly in the Serra Gaúcha, the mountain area of the state of Rio Grande do Sul, which is responsible for 90% of the domestic wine production. However, in recent years, two new production regions have developed: the Campanha, the plains to the south and the Serra do Sudeste, the hills to the southeast of the state. Analysis of isotopic ratios of ¹⁸O/¹⁶O of wine water, ¹³C/¹²C of ethanol, and of minerals were used to characterize wines from different regions. The isotope analysis of δ¹⁸O of wine water and minerals Mg and Rb were the most efficient to differentiate the regions. By using isotope and mineral analysis, and discrimination analysis, it was possible to classify the wines from south Brazil.     

Modulation of the microwave quantum-magneto-absorption

Modulation of the quantum electromagnetic excitations in bismuth is reported. The effect is shown as peculiar of these excitations and an explanation in terms of a previous theory is given.     

Efficient Access to Deuterated and Tritiated Nucleobase Pharmaceuticals and Oligonucleotides using Hydrogen‐Isotope Exchange

A general approach for the efficient hydrogen‐isotope exchange of nucleobase derivatives is described. Catalyzed by ruthenium nanoparticles, using mild reaction conditions, and involving either D₂ or T₂ as isotopic sources, this reaction possesses a wide substrate scope and a high solvent tolerability. This novel method facilitates the access to essential diagnostic tools in drug discovery and development: tritiated pharmaceuticals with high specific activities and deuterated oligonucleotides suitable for use as internal standards during LC‐MS quantification.     

Semitotal Domination in Claw-Free Cubic Graphs

In this paper, we continue the study of semitotal domination in graphs in [Discrete Math. 324, 13–18 (2014)]. A set \({S}\) of vertices in \({G}\) is a semitotal dominating set of \({G}\) if it is a dominating set of \({G}\) and every vertex in \({S}\) is within distance 2 of another vertex of \({S}\). The semitotal domination number, \({{\gamma_{t2}}(G)}\), is the minimum cardinality of a semitotal dominating set of \({G}\). This domination parameter is squeezed between arguably the two most important domination parameters; namely, the domination number, \({\gamma (G)}\), and the total domination number, \({{\gamma_{t}}(G)}\). We observe that \({\gamma (G) \leq {\gamma_{t2}}(G) \leq {\gamma_{t}}(G)}\). A claw-free graph is a graph that does not contain \({K_{1, \, 3}}\) as an induced subgraph. We prove that if \({G}\) is a connected, claw-free, cubic graph of order \({n \geq 10}\), then \({{\gamma_{t2}}(G) \leq 4n/11}\).     

Tuning electronic eigenvalues of benzene via doping

Using variable atomic numbers within molecular grand-canonical ensemble theory, the highest occupied Kohn-Sham eigenvalue of isoelectronic benzene derivatives is tuned. The performed transmutational changes correspond to the iterative doping with boron and nitrogen. The molecular Fukui function proves to be a reliable index in order to predict the changes in the highest occupied molecular orbital eigenvalue due to doping.     

Highly stable 3,4,9,10-perylenediimide radical anions immobilized in robust zirconium phosphonate self-assembled films

Self-assembled thin films of 3,4,9,10-perylenediimides (PDIs) containing up to 50 PDI layers were grown on quartz slides using the zirconium phosphonate technique. When the films were immersed in aqueous solutions of the sodium dithionite reducing agent, in situ reduction of the dye was observed, generating a purple film containing PDI radical anions. The PDI radical anions formed within the films were rather stable, persisting for several minutes in the presence of atmospheric oxygen. Atomic force microscopy (AFM) images showed that the film surface was rather smooth and pinhole-free.     

Tetrathiophene on Graphite: Molecular Dynamics Simulations

Summary: We describe molecular dynamics simulations of α‐tetrathiophene molecules deposited on a flat graphite substrate, at two different temperatures (300 K and 400 K) and several degrees of coverage (from approximately one to three molecular layers). The simulations employ a modified version of the CFF91 force field, with the torsion parameters tailored on high‐level ab initio calculations on 2,2′‐bithiophene. We found that the molecules in the first layer were relatively planar and packed against the underlying surface, while those outside it were not arranged in well‐defined layers and were more conformationally disordered. On the time scale of the simulation, the molecules did not crystallize but rather achieved a liquid crystalline‐like state with their average director parallel to the surface.

Side view of the final configuration in the simulation of 24 tetrathiophenes at 300 K. Molecules are depicted with different shades of gray according to their z coordinate (first, second or third layer).     

Atomistic simulation of structure and dynamics of columnar phases of hexabenzocoronene derivatives

Using atomistic molecular dynamics simulations we study solid and liquid crystalline columnar discotic phases formed by alkyl-substituted hexabenzocoronene mesogens. Correlations between the molecular structure, packing, and dynamical properties of these materials are established.