Although vodka is a reasonably pure mixture of alcohol and water, beverage drinks typically show differences in appeal among brands. The question immediately arises as to the molecular basis, if any, of vodka taste perception. This study shows that commercial vodkas differ measurably from ethanol-water solutions. Specifically, differences in hydrogen-bonding strength among vodkas are observed by (1)H NMR, FT-IR, and Raman spectroscopy. Component analysis of the FT-IR and Raman data reveals a water-rich hydrate of composition E x (5.3 +/- 0.1)H(2)O prevalent in both vodka and water-ethanol solutions. This composition is close to that of a clathrate-hydrate observed at low temperature, implying a cage-like morphology. A structurability parameter (SP) is defined by the concentration of the E x (5.3 +/- 0.1)H(2)O hydrate compared to pure ethanol-water at the same alcohol content. SP thus measures the deviation of vodka from "clean" ethanol-water solutions. SP quantifies the effect of a variety of trace compounds present in vodka. It is argued that the hydrate structure E x (5.3 +/- 0.1)H(2)O and its content are related to the perception of vodka.

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Ultra-small angle x-ray scattering (USAXS), small-angle neutron scattering (SANS), x-ray reflectometry (XRR) and neutron reflectometry (NR) were used to probe structure evolution induced by sealing of anodized aluminum. While cold nickel acetate sealing and hot-water sealing decrease pore size, these methods do not alter the cylindrical porous framework of the anodic aluminum oxide layer. Hot nickel acetate both fills the pores and deposits on the air surface (air-oxide interface), leading to low porosity and small mean pore radius (39 Å). Electrochemical impedance spectroscopy and direct current polarization show that samples sealed by hot nickel acetate outperform all other sealing methods. Recent studies on new sealants and sealing processes include cold nickel acetate sealing, [13] sodium silicate sealing,[18] nickel fluoride sealing, [10, 18] Cr 2 O 3 sealing,[19] sodium acetate sealing, [12, 14] cerium acetate sealing, [17, 20] cerium nitrate and yttrium sulfate sealing, [9]sol-gel sealing, [16] and even an expensive sealing process using polytetrafluroethylene (PTFE).[19] In spite of these efforts to improve the performance, more convenient and effective processes are still needed. [19] In developing the new sealing methods, DC polarization (DCP) [10,19,21,22] and electrochemical impedance spectroscopy (EIS) [13, 15-17, 20, 23-25] have been used to compare the corrosion performance between different methods. For hydrothermal sealing it is believed that boehmite (AlOOH) is produced at temperatures above 80 ºC, while less soluble than hydrargillite (Al(OH) 3 ) that is formed at low temperatures. For cold sealing methods, however, the mechanism has not been completely elucidated.[18] The structural alternation induced by sealing and the relationship between pore evolution and corrosion resistance have not been investigated.In this work, we use x-ray reflectivity (XRR), neutron reflectivity (NR), ultra-small-angle x-ray scattering (USAXS) and small-angle neutron scattering (SANS) to investigate the morphological changes induced by sealing. Cold nickel acetate sealing is of particular interest as it has been reported to be a promising alternative to conventional hot water sealing. [10,13,17,20] Our results, however, show that both Ni and high temperature are required for effective corrosion protection.

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