Geographic origin of southern Brazilian wines by carbon and oxygen isotope analyses

We present a method that can differentiate between the varieties of grapes and the vintages of wines and show the relationship between the grapes, the wine and the geographic location. The place of origin and its geographic and climatic characteristics were determined by the isotopic ratios, ¹³C/¹²C of the ethanol and ¹⁸O/¹⁶O of the water content of wine (wine water), for southern Brazil wines. The producing subregions of Pinto Bandeira, Vale dos Vinhedos and Nova Pádua showed differences in the temperature, rainfall and humidity conditions used for the production under microvinification conditions of Merlot and Cabernet Sauvignon varieties, in the harvests of 2005 and 2006. An isotope ratio mass spectrometer coupled to an elemental analyzer was used to measure the ¹³C/¹²C of ethanol and the ¹⁸O/¹⁶O of wine water. Regardless of the grape variety used, it was possible to determine the subregion through measurement of the δ¹⁸O values in both harvests. The altitudes of the different subregions led to statistical differences and demonstrated an influence mainly on the δ¹⁸O values of wine water. The δ¹⁸O value of wine water was determined to be more selective for the determination of the cultivation subregions than the δ¹³C value of the ethanol. The altitude and latitude influenced mainly the δ ¹⁸O values of wine water and the ethanol. The climatic influences are more noteworthy in distinguishing the year of the harvest than the cultivation subregion. Copyright © 2010 John Wiley & Sons, Ltd.     

Bis(salicylaldiminate) copper(II) and palladium(II) complexes: towards columnar mesophases

Copper and palladium complexes of new salicylaldimines derived from 3,4,5-tridecyloxyaniline, 2,3,4-tridecyloxyaniline and 4-decyloxyaniline have been synthesized and characterized. All the ligands bear four or more aliphatic chains with the aim of inducing columnar mesophases at low temperatures. In particular, metal complexes derived from 4-(3,4,5-tridecyloxybenzoyloxy)-salicyliden-3,4,5-tridecyloxyaninile display rectangular columnar mesophases at (or near) room temperature. These mesophase assignments have been confirmed by X-ray diffraction. A significant decrease of the melting points of the compounds is observed in the tridecyloxyaniline derivatives compared with those of similar complexes derived from mono- or di-decyloxyaniline.     

Anisotropic properties of the microwave magneto-dissipation in high-T c superconducting films

We report measurements of the magnetic field dependent microwave dissipation at 21 GHz in Bi₂Sr₂CaCu₂O_8+x epitaxial films and in oriented YBa₂Cu₃O_7?σ films, by means of the end-wall-replacement cavity technique. The power reflected by the tuned cavity is measured as a function of the external magnetic fieldH and of the angle ε betweenH and the (a, b), planes, at fixed temperatures. In Bi₂Sr₂CaCu₂O_8+x , apart from a narrow (Δε≈0.5°) angular range close to the parallel orientation, the strongly anisotropic dissipation exhibits striking scaling properties: all the data at fixed temperature can be made to collapse on a single curve with a simple angular scaling of the magnetic field:H→H/f(ε). It is found that the anisotropy ratiof(0°)/f(90°) increases with temperature. It is shown that the scaling functionf(ε) and its temperature evolution are in agreement with the model for a quasi-2D superconductor. In YBa₂Cu₃O_7-σ the presence of the flux-flow dissipation prevents the application of a scaling procedure, and a specific model must be applied. We obtain that the anisotropy is almost constant with the temperature, as predicted for a three-dimensional, anisotropic superconductor.     

Single-test determination of the friction coefficient and stress-strain curve for application in metal-forming analyses

The compression test of a ring is customarily used to determine the friction coefficient in metal-forming problems. The aim of this paper is to describe a procedure to obtain, for metals in the large deformation range, the stress-strain curve and friction coefficient through the same test. The friction coefficient is evaluated by comparing curves obtained by a finite element code with the experimental curves. The stress-strain curve is obtained by inverting an analytical solution, calculated by a lower-upper-bound approach. Good results in terms of accuracy are obtained.     

Preparation and characterization of Zonyl-coated nanodiamonds with antifouling properties

The paper reports on covalent linking of a modified amphiphilic polymer, the alkynyl-terminated Zonyl, to azide-terminated nanodiamonds by click chemistry. An analysis of the hybrid particle stability is presented based on size and zeta potential measurements. The antifouling character of the grafted nanodiamonds was investigated using bovine serum albumin as a model protein. The protein adsorption was quantified using a Bradford assay and found to be reduced by 30% in the presence of the Zonyl layer.     

Characterization of a novel water-soluble 3,4,9,10-perylenetetracarboxylic diimide in solution and in self-assembled zirconium phosphonate thin films

The properties of N,N'-bis(2-phosphonoethyl)-3,4,9,10-perylenetetracarboxylic diimide (PPDI), a water-soluble perylene dye, have been studied in solution and in thin films. Absorption spectra showed that PPDI exists in the monomeric form in water/ethanol (1:1) and water/dimethyl sulfoxide (DMSO) (3:7) mixtures, but forms dimers in water and higher aggregates in ethanol. The PPDI monomer is highly fluorescent, in contrast to the dimers and aggregates, which are nonfluorescent. The monomer/dimer equilibrium was conveniently followed in a water/ethanol (7:3) mixture by varying the dye concentration. An equilibrium constant of K = 1.25 x 10(5) M(-1) was estimated for the dimerization process in this solvent mixture. The addition of cetyl trimethylammonium bromide (CTAB), a cationic surfactant, to aqueous solutions of PPDI resulted in the dissociation of the dimers, showing that the dye was incorporated into the micellar phase. Self-assembled thin films of PPDI were grown on both silica gel particles and flat surfaces, using zirconium phosphonate chemistry. The growth of multilayered films on flat surfaces was monitored by ellipsometry (silicon substrates) and UV/Vis spectroscopy (quartz slides), and was linear with the number of deposition cycles. No fluorescence was detected from the PPDI films, and the absorption spectra of the films were quite similar to the spectrum of the compound in ethanol, indicating that the dye molecules were stacked in the films. Mixed monolayers containing PPDI and N,N'-bis(2-phosphonoethyl)-1,4,5,8-naphthalenediimide (PNDI) on quartz were also prepared. Monolayers obtained by codeposition from solutions containing both PPDI and PNDI were richer in PPDI, even when the solution contained a large excess of the naphthalene derivative, showing that pi-stacking of PPDI is an important driving force in the formation of the films.