No abstract

Although in modern societies fermented beverages are associated with socializing, celebration, and ritual, in ancient times they were also important sources of essential nutrients and potable water. In Mesoamerica, pulque, an alcoholic beverage produced from the fermented sap of several species of maguey plants (Agavaceae; Fig. 1) is hypothesized to have been used as a dietary supplement and risk-buffering food in ancient Teotihuacan (150 B.C. to A.D. 650). Although direct archaeological evidence of pulque production is lacking, organic residue analysis of pottery vessels offers a new avenue of investigation. However, the chemical components of alcoholic beverages are water-soluble, greatly limiting their survival over archaeological timescales compared with hydrophobic lipids widely preserved in food residues. Hence, we apply a novel lipid biomarker approach that considers detection of bacteriohopanoids derived from the ethanol-producing bacterium Zymomonas mobilis for identifying pulque production/consumption in pottery vessels. Gas chromatography-mass spectrometry selected ion monitoring (m/z 191) of lipid extracts of >300 potsherds revealed characteristic bacteriohopanoid distributions in a subset of 14 potsherds. This hopanoid biomarker approach offers a new means of identifying commonly occurring bacterially fermented alcoholic beverages worldwide, including palm wine, beer, cider, perry, and other plant sap-or fruit-derived beverages [Swings J, De Ley J (1977)

New lanthanide complexes with 4,5-bis(diphenyl)phosphoranyl-1,2,3-triazolate (L(-)), LnL(3).nH(2)O (1-8) and LnL(3)(phen).nH(2)O (9-16) (Ln = La, Ce, Nd, Sm, Eu, Gd, Tb, Er), have been prepared and spectroscopically characterized. The structures of LnL(3).nH(2)O (Ln = La, Ce, Nd, Sm and Gd) were determined by X-ray crystallography. The metal centers exhibit a distorted trigonal dodecahedron coordination environment with two symmetrically O,O-bidentate ligands and one unsymmetrically O,N- ligand attached to the metal; two oxygen atoms from neighboring dimethyl sulfoxide (DMSO) molecules complete the coordination sphere. This unsymmetrical ligand coordination behavior was also identified in solution through (31)P{(1)H} NMR studies. Photoluminescence spectroscopy experiments in CH(2)Cl(2) for both types of complexes containing Eu(III) (6, 14) and Tb(III) (7, 15) exhibit strong characteristic red and green emission bands for Eu(III) and Tb(III), respectively. Furthermore, NdL(3) (phen).5H (2)O (11) displays emission in the near-infrared spectral region ((4)F(3/2) --> (4)F(9/2) at 872 nm and (4)F(3/2) --> (4)F(11/2) at 1073 nm). The complexes containing 1,10-phenantroline exhibit higher quantum yields upon excitation at 267 nm, indicating that this auxiliary ligand promotes the luminescence of the complexes; however, luminescence lifetimes (tau) in this case are shorter than those of the LnL(3).nH(2)O series.

The interaction of the 4,5-bis(diphenylthiophosphinoyl)-1,2,3-triazolate (SPTz −) with different gold surfaces was investigated (nanoparticles, an electrode, and flat sheets). Studies on binding affinity of this dithiophosphin-triazolate on a gold electrode were performed by cyclic voltammetry (CV). Voltammograms exhibit two reductive desorption and only one oxidative readsorption, indicating that once reabsorbed, the molecule achieves a unique conformation. The morphology and average size of modified gold nanoparticles were studied by transmission electron microscopy (TEM) (av. diameter of 5.9 ± 1.8 nm). Further characterization was made by UV-visible (UV-vis) spectroscopy showing surface plasmon resonance (SPR) at about 580 nm. The bonding configurations of SPTz − on gold have also been investigated by comparing the FT-IR and FT-Raman spectra. The 31 P{ 1 H} NMR spectrum of capped nanoparticles exhibited two sharp signals at 30.3 and 29.6 ppm and a very broad signal at 72.7 ppm. X-ray photoelectron spectroscopy (XPS) showed SPTz − can accomplish a strong interaction with gold nanoparticles through bonds involving a sulfur atom and a nitrogen from the triazole ring with a free terminal PS group, forming self-assembled monolayers (SAM). This may allow subsequent functionalization through free S/N atoms of the formed SAMs. The SPTz − packing led to a reduction in packing density that permits large spaces between adsorbed headgroups and the inclusion of carbon and oxygen impurities from small molecules; nevertheless, oxidized sulfur or nitrogen species were not detected, indicating the chemical stability of the obtained SAMs.