Josiah Willard Gibbs and Pierre Maurice Duhem: two diverging personalities, and scientific styles.

In this essay, I will compare the character, scientific style, and writing style of the American physicist Josiah Willard Gibbs and the French physicist Pierre Maurice Duhem. I begin with biographical notes to portray some significant moments of their lives. I will contrast their characters and scientific styles as manifested in their social and scientific activity influenced by the cultural traditions of their countries and the social and scientific milieu of their time.

The double transfer of thermodynamics: From physics to chemistry and from Europe to America.

The aim of this study is twofold: to explore, first, the influence of the intellectual and social conditions on the transfer of thermodynamics to chemistry and thereby the making of chemical thermodynamics, and second, the way that this knowledge was transferred from Europe to America. Consequently, it is of interest to examine the methodological approaches used by physicists and chemists to transfer thermodynamics to chemistry, to evaluate the potential of this science to offer solutions to existing chemical problems, and to discuss the attitude of the scientific community towards these new ideas. The development of chemical thermodynamics in America followed a different route compared to the European experience.

NMR Spectroscopy Protocols for Food Metabolomics Applications.

NMR spectroscopy has become an indispensable tool for the metabolic profiling of foods and food products. In the present protocol, we report an analytical approach based on liquid-state NMR for the determination of polar and nonpolar metabolites in some common liquid (wine, spirits, juice) and solid (cheese, coffee, honey) foods. Although the diversity of foods precludes the use of a single protocol, with small modifications, the proposed methodologies can be adapted to a broader range of foodstuffs.

Quality assessment and authentication of virgin olive oil by NMR spectroscopy: a critical review.

Nuclear Magnetic Resonance (NMR) Spectroscopy has been extensively used for the analysis of olive oil and it has been established as a valuable tool for its quality assessment and authenticity. To date, a large number of research and review articles have been published with regards to the analysis of olive oil reflecting the potential of the NMR technique in these studies. In this critical review, we cover recent results in the field and discuss deficiencies and precautions of the three NMR techniques ((1)H, (13)C, (31)P) used for the analysis of olive oil.

Simultaneous determination of phenolic compounds and triterpenic acids in oregano growing wild in Greece by 31P NMR spectroscopy.

(31)P nuclear magnetic resonance (NMR) spectroscopy was used to detect and quantify simultaneously a large number of phenolic compounds and the two triterpenic acids, ursolic acid and oleanolic acid, extracted from two oregano species Origanum onites and Origanum vulgare ssp. Hirtum using two different organic solvents ethanol and ethyl acetate. This analytical method is based on the derivatization of the hydroxyl and carboxyl groups of these compounds with the phosphorous reagent 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxa phospholane and the identification of the phosphitylated compounds on the basis of the (31)P chemical shifts.

Influence of harvest year, cultivar and geographical origin on Greek extra virgin olive oils composition: a study by NMR spectroscopy and biometric analysis.

Two hundred twenty-one extra virgin olive oils (EVOO) were extracted from four olive mono-cultivars (Koroneiki, Tsounati, Adramitini, and Throubolia) originated from four divisions of Greece (Peloponnesus, Crete, Zakynthos, and Lesvos) and collected in five harvesting periods (2002-2006 and 2007-2008). All samples were chemically analysed by means of (1)H and (31)P NMR spectroscopy and characterised according to their content in fatty acids, phenolic compounds, diacylglycerols, total free sterols, free acidity, and iodine number. The influence of cultivars on the compositional data of the EVOO samples according to harvest year and geographical origin was examined by means of the forward stepwise canonical discriminant analysis (CDA) and classification binary trees (CBT).

Detection of refined olive oil adulteration with refined hazelnut oil by employing NMR spectroscopy and multivariate statistical analysis.

NMR spectroscopy was employed for the detection of adulteration of refined olive oil with refined hazelnut oil. Fatty acids and iodine number were determined by (1)H NMR, whereas (31)P NMR was used for the quantification of minor compounds including phenolic compounds, diacylglycerols, sterols, and free fatty acids (free acidity). Classification of the refined oils based on their fatty acids content and the concentration of their minor compounds was achieved by using the forward stepwise canonical discriminant analysis (CDA) and the classification binary trees (CBTs).

Detection and quantification of phenolic compounds in olive oil by high resolution 1H nuclear magnetic resonance spectroscopy.

High resolution (1)H NMR spectroscopy has been employed as a versatile and rapid method to analyze the polar fraction of extra virgin olive oils containing various classes of phenolic compounds. The strategy for identification of phenolic compounds is based on the NMR chemical shifts of a large number of model compounds assigned by using two-dimensional (2D) NMR spectroscopy. Furthermore, 2D NMR was applied to phenolic extracts in an attempt to discover additional phenolic compounds.

Conformational properties of the macrocyclic trichothecene mycotoxin verrucarin A in solution.

Phase-sensitive nuclear Overhauser enhancement spectroscopy (NOESY) experiments, (3)J couplings and computational molecular modeling (MM2* and MMFF force fields) were employed to examine the conformational properties of verrucarin A in chloroform solutions. The MMFF force field calculations resulted in a family of 12 low-energy structures along with their populations, the latter being determined by the NMR analysis of molecular flexibility in solution(NAMFIS) deconvolution analysis. The concluded model was capable of reproducing successfully the experimental NOESY cross-peak volumes and the proton-coupling constants.

Determination of phospholipids in olive oil by 31P NMR spectroscopy.

A nondestructive analytical method based on NMR spectroscopy was developed for the determination of phospholipids in olive oil. The phospholipids extracted from virgin olive oil with a mixture of ethanol/water (2:1 v/v) were identified and quantified by high resolution (31)P NMR spectroscopy. The main phospholipids found in olive oil were phosphatidic acid, lyso-phosphatidic acid, and phosphatidylinositol.

Geographical characterization of greek virgin olive oils (cv. Koroneiki) using 1H and 31P NMR fingerprinting with canonical discriminant analysis and classification binary trees.

This work deals with the prediction of the geographical origin of monovarietal virgin olive oil (cv. Koroneiki) samples from three regions of southern Greece, namely, Peloponnesus, Crete, and Zakynthos, and collected in five harvesting years (2001-2006). All samples were chemically analyzed by means of 1H and 31P NMR spectroscopy and characterized according to their content in fatty acids, phenolics, diacylglycerols, total free sterols, free acidity, and iodine number.

Determination of water content in olive oil by 31P NMR spectroscopy.

A method for moisture determination in olive oil using 31P NMR spectroscopy is developed. This method is based on the replacement of the hydrogen atoms of water molecules with the tagging agents 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane and diphenylphosphinic chloride. Both reagents were successful in determining moisture in olive oil.

31P NMR spectroscopy in the quality control and authentication of extra-virgin olive oil: a review of recent progress.

This review is a brief account on the application of a novel methodology to the quality control and authentication of extra-virgin olive oil. This methodology is based on the derivatization of the labile hydrogens of functional groups, such as hydroxyl and carboxyl groups, of olive oil constituents with the phosphorus reagent 2-chloro-4,4,5,5-tetramethyldioxaphospholane, and the use of the (31)P chemical shifts to identify the phosphitylated compounds. Various experimental aspects such as pertinent instrumentation, sample preparation, acquisition parameters and properties of the phosphorus reagent are reviewed.

Comparison of analytical methodologies based on 1h and 31p NMR spectroscopy with conventional methods of analysis for the determination of some olive oil constituents.

The present study was designed to assess the agreement between analytical methodologies based on 1H and 31P NMR spectroscopy and conventional analytical methods (titration, gas chromatography, and high performance liquid chromatography) for measuring certain minor and major constituents (free acidity, fatty acids, iodine value, and phenolic compounds) of olive oil. The standard deviations of the NMR method were comparable to those of the conventional methods, except perhaps those of the total hydroxytyrosol and total tyrosol. Linear regression analyses showed strong correlations between NMR and conventional methods for free acidity, total hydroxytyrosol, total tyrosol, total diacylglycerols, (+)-pinoresinol, (+)-1-acetoxypinoresinol, and apigenin; good correlations for linoleic acid, free hydroxytyrosol, and free tyrosol; and weak correlations for oleic acid, linolenic acid, saturated fatty acids, and luteolin.

Conformational analysis of ochratoxin a by NMR spectroscopy and computational molecular modeling.

Two-dimensional NMR spectroscopy has been used for a complete assignment of the proton and carbon-13 spectra of the metabolite from Aspergillus ochraceus, ochratoxin A. In addition, phase-sensitive nuclear Overhauser effect spectrometry experiments and computational molecular modeling (MM2 and MMFF force field programs) have been employed to examine the conformational properties of ochratoxin A in chloroform solutions. Particular attention has been given to intramolecular hydrogen-bonding formation involving the phenolic group on dihydroisocoumarin, which may be responsible for the toxic mechanism of ochratoxin A.

Novel approach to the detection and quantification of phenolic compounds in olive oil based on 31P nuclear magnetic resonance spectroscopy.

31P NMR spectroscopy has been employed to detect and quantify phenolic compounds in the polar fraction of virgin olive oil. This novel analytical method is based on the derivatization of the hydroxyl and carboxyl groups of phenolic compounds with 2-chloro-4,4,5,5-tetramethyldioxaphospholane and the identification of the phosphitylated compounds on the basis of the 31P chemical shifts. Quantification of a large number of phenolic compounds in virgin olive oil can be accomplished by integration of the appropriate signals in the 31P NMR spectrum and the use of the phosphitylated cyclohexanol as internal standard.

Separation and identification of phenolic compounds in olive oil by coupling high-performance liquid chromatography with postcolumn solid-phase extraction to nuclear magnetic resonance spectroscopy (LC-SPE-NMR).

This study reports the first application of the hyphenated LC-SPE-NMR technique using postcolumn solid-phase extraction to the direct analysis of phenolic compounds in the polar part of olive oil. Apart from the identification and structure elucidation of simple phenols (hydroxytyrosol, tyrosol, vanillic acid, vanillin, p-coumaric acid, hydroxytyrosol, and tyrosol acetates), lignans (pinoresinol and 1-acetoxypinoresinol), flavonoids (apigenin and luteolin), and a large number of secoiridoid derivatives, this technique enables the identification of several new phenolic components, which had not been reported previously as constituents in the polar part of olive oil.

13C Nuclear magnetic relaxation study of segmental dynamics of hyaluronan in aqueous solutions.

(13)C spin-lattice relaxation times (T(1)) and nuclear Overhauser enhancements (NOE) were measured as a function of temperature and magnetic field strength for the hetero-polysaccharide hyaluronan in water solutions. The relaxation data of the endocyclic ring carbons were successfully interpreted in terms of chain segmental motions by using the bimodal time-correlation function of Dejean de la Batie, Laupretre and Monnerie. On the basis of the calculated correlation times for segmental motion and amplitudes of librational motions of the C-H vectors at the various carbon sites of the HA repeating unit, we concluded that intramolecular hydrogen bonding of the secondary structure of HA plays a major role in the conformational flexibility of this carbohydrate molecule.

Detection of extra virgin olive oil adulteration with lampante olive oil and refined olive oil using nuclear magnetic resonance spectroscopy and multivariate statistical analysis.

High-field 31P NMR (202.2 MHz) spectroscopy was applied to the analysis of 59 samples from three grades of olive oils, 34 extra virgin olive oils from various regions of Greece, and from different olive varieties, namely, 13 samples of refined olive oils and 12 samples of lampante olive oils. Classification of the three grades of olive oils was achieved by two multivariate statistical methods applied to five variables, the latter being determined upon analysis of the respective 31P NMR spectra and selected on the basis of one-way ANOVA.

Kinetics of diglyceride formation and isomerization in virgin olive oils by employing 31P NMR spectroscopy. Formulation of a quantitative measure to assess olive oil storage history.

Diacylglycerol isomers and free acidity were determined for five extra virgin olive oils of different initial acidities by employing a facile (31)P NMR methodology as a function of storage time and storage conditions. The kinetic treatment of the hydrolysis of triacylglycerols (TGs) and the isomerization of 1,2-diacylglycerols (1,2-DGs) to 1,3-diacylglycerols (1,3-DGs) during storage of 18 months at ambient temperature in the dark and light and at 5 degrees C in the dark showed that the isomerization is strongly dependent on the rate of the TGs hydrolysis, the initial free acidity (H(0)) of the virgin olive oil samples, and storage conditions. Although the time-evolution of the diacylglycerols (DGs) depends on the TGs hydrolysis, the ratio D of the concentration of 1,2-DGs to the total amount of DGs was found to be independent of this factor.

Classification of edible oils by employing 31P and 1H NMR spectroscopy in combination with multivariate statistical analysis. A proposal for the detection of seed oil adulteration in virgin olive oils.

A combination of (1)H NMR and (31)P NMR spectroscopy and multivariate statistical analysis was used to classify 192 samples from 13 types of vegetable oils, namely, hazelnut, sunflower, corn, soybean, sesame, walnut, rapeseed, almond, palm, groundnut, safflower, coconut, and virgin olive oils from various regions of Greece. 1,2-Diglycerides, 1,3-diglycerides, the ratio of 1,2-diglycerides to total diglycerides, acidity, iodine value, and fatty acid composition determined upon analysis of the respective (1)H NMR and (31)P NMR spectra were selected as variables to establish a classification/prediction model by employing discriminant analysis. This model, obtained from the training set of 128 samples, resulted in a significant discrimination among the different classes of oils, whereas 100% of correct validated assignments for 64 samples were obtained.

Ochratoxin A concentrations in Greek domestic wines and dried vine fruits.

A survey for the presence of ochratoxin A (OTA) was conducted from 1995 to 1999 on 268 locally produced commercial wines, and on 81 samples of domestic dried vine fruits (currants and sultanas) collected between 1998 and 2000 from sites of primary storage and processing. The OTA concentration in red dry wines (n = 104, median = 0.09 microgram l(-1)) was not significantly different from that for white (n = 118, median = 0.

Determination of the diglyceride content in greek virgin olive oils and some commercial olive oils by employing (31)P NMR spectroscopy.

In this study, the diglyceride contents of 96 samples of virgin olive oils from the regions of Crete, Lesvos, Messinia, Pilion, Zakynthos, Halkidiki, and Ilia, 15 samples of commercial extra virgin and pure olive oils, and 3 samples each of refined olive oils and pomace oils were determined by a facile method introduced in a previous publication. This method is based on the phosphitylation of the free hydroxyls of the diglycerides with 2-chloro-4,4,5,5-tetramethyldioxaphospholane and the integration of the appropriate peaks in the (31)P NMR spectra. This preliminary study showed interesting trends in the diglyceride content of the virgin olive oils from the various regions of Greece that can be used as simple criteria to assess the olive oil characteristics.