Analysis of the volatile compounds of Teucrium flavum L. subsp. flavum (Lamiaceae) by headspace solid-phase microextraction coupled to gas chromatography with flame ionisation and mass spectrometric detection

In this study, a headspace solid-phase microextraction (HS-SPME) method, in combination with gas chromatography flame ionisation detector and gas chromatography-mass spectrometry, has been developed for use in the analysis of the volatile compounds of Teucrium flavum L. subsp. flavum, a plant whose particular fragrance is used in the preparation of flavoured wines, bitters and liqueurs, or as a substitute for hops in the flavouring of beer. The tested fibres were 100?μm poly(dimethylsiloxane) (PDMS), the 65?μm PDMS/divinylbenzene (DVB) and 50/30?μm DVB-carboxen-PDMS. The best fibre was found to be PDMS when working in the following conditions: 60°C temperature, 30?min extraction time, 30?mg sample amount, 1?mm sample particle size. The HS-SPME method permitted the identification (95.8-97.8%) of 76 (dry) and 66 (fresh) different volatiles. In addition, we discovered that the presence of water in the sample can enhance the absolute quantity of alcoholic compounds such as 1-octen-3-ol and reduce the presence of esters such as methyl geranate.     

Bifurcations of a lattice gas flow under external forcing

We study the behavior of a Frisch-Hasslacher-Pomeau lattice gas automaton under the effect of a spatially periodic forcing. It is shown that the lattice gas dynamics reproduces the steady-state features of the bifurcation pattern predicted by a properly truncated model of the Navier-Stokes equations. In addition, we show that the dynamical evolution of the instabilities driving the bifurcation can be modeled by supplementing the truncated Navier-Stokes equation with a random force chosen on the basis of the automaton noise.     

Synthesis of New Nucleosides by coupling of chloropurines with 2- and 3-deoxy derivatives of N-methyl-D-ribofuranuronamide

The synthesis of new deoxyribose nucleosides by coupling chloropurines with modified D -ribose derivatives is reported. The methyl 2-deoxy-N-methyl-3-O-(p-toluoyl)-α-D -ribofuranosiduronamide (α-D - 8 ) and the corresponding anomer β-D - 8 were synthesized starting from the commercially available 2-deoxy-D -ribose ( 1 ) (Scheme 1). Reaction of α-D - 8 with the silylated derivative of 2,6-dichloro-9H-purine ( 9 ) afforded regioselectively the N⁹-(2′-deoxyribonucleoside) 10 as anomeric mixture (Scheme 2), whereas β-D - 8 did not react. Glycosylation of 9 or of 6-chloro-9H-purine ( 17 ) with 1,2-di-O-acetyl-3-deoxy-N-methyl-β-D -ribofuranuronamide ( 13 ) yielded only the protected β-D -anomers 14 and 18 , respectively (Scheme 3). Subsequent deacetylation and dechlorination afforded the desired nucleosides β-D - 11 , β-D - 12,15 , and 16 . The 3′-deoxy-2-chloroadenosine derivative 15 showed the highest affinity and selectivity for adenotin binding site vs. A₁ and A_2A adenosine receptor subtypes.     

Alkannin/shikonin mixture from roots of Onosma echioides (L.) L.: extraction method study and quantification

This work reports the extraction procedures of alkannin/shikonin mixture from roots of six populations of Onosma echioides, by means of three extraction techniques: Soxhlet extraction, maceration and rapid solid-liquid dynamic extraction (RSLDE). Five solvents with different polarity (hexane, petroleum ether, chloroform, ethyl acetate, methanol) were also studied. Analysis of the extracts was performed by an HPLC-DAD (diode array detector) system. The most efficient extraction technique was Soxhlet procedure using ethyl acetate for 6 h. Studied samples of O. echioides showed an alkannin/shikonin content in the range of 0.02-0.24 mg/kg. Other naphthoquinone derivatives (deoxyalkannin/deoxyshikonin and 5,8-dihydroxy-2-(4-methyl-6-oxo-5,6-dihydro-2H-pyran-2-yl)-[1,4]naphthoquinone and arnebin-6) were found for the first time in O. echioides and characterized in the extracts using HPLC-MS apparatus equipped with an ESI ionization source.     

Determination of ink photoinitiators in packaged beverages by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry

A new analytical method, using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) techniques, was developed for the determination in packaged food beverages of five ink photoinitiator residues: 2-isopropylthioxanthone (ITX), benzophenone, 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), 1-hydroxycyclohexyl-1-phenyl ketone (IRGACURE 184) and ethyl-4-dimethylaminobenzoate (EDAB). Samples were extracted from selected beverages (milk, fruit juices and wine) and relative packagings, using n-hexane and dichloromethane, respectively, purified on solid-phase extraction (SPE) silica gel cartridges, and then analyzed in GC/MS and LC/MS. The recovery percentages, obtained spiking the beverage samples at concentrations of 4 and 10 microgl(-1) with a standard mixture of photoinitiators, were in the range 42-108% (milk), 50-84% (wine), and 48-109% (fruit juices). The repeatability of the method was assessed in all cases by the % of correlation value, that was lower than 19%. The lowest limits of detection (LODs) and limits of quantification (LOQs), obtained using GC/MS, were in the range 0.2-1 and 1-5 microgl(-1), respectively. The method was applied to the analysis of forty packaged food beverages (milk, fruit juices and wine samples). The most significant contamination was that of benzophenone, found in all samples in a concentration range of 5-217mugl(-1). Its presence was confirmed by an LC/Atmospheric-Pressure PhotoIonization (APPI)/MS/MS analysis. The photoinitiator (EHDAB) was found in eleven out of forty beverages in a concentration range of 0.13-0.8 microgl(-1). Less important was the ITX contamination, found in three out of forty samples in a range 0.2-0.24 microgl(-1). The work proposes a new method to analyze ink photoinitiator residues in polycoupled carton packaging and in contained food beverages.     

Synthesis and Adenosine Deaminase Inhibitory Activity of 3′-Deoxy-1-deazaadenosines

New 1-deazapurine nucleosides were synthesized by coupling 2,6-dichloro-1-deaza-9H-purine (=5,7-dichloro-3H-imidazo[4,5-b]pyridine) with a 3-deoxyribose derivative by the acid-catalyzed fusion method. The condensation reaction gave an anomeric mixture of the N⁹-β-D - and N⁹-α-D -3′-deoxynucleosides, which were treated with methanolic ammonia at room temperature to obtain the deprotected derivatives. Reaction of the β-D -anomer with different amines gave 2-chloro-N⁶-substituted nucleosides, which were dechlorinated to give the corresponding 3′-deoxy-1-deazaadenosines. Biological studies on adenosine deaminase from calf intestine showed that the new compounds are inhibitors of the enzyme, the 3′-deoxy-1-deazaadenosine being the most potent one with a K_i of 2.6 μM .     

Qualitative criteria of admissibility for enforced agreements

It is desirable that artificial agents can help each other when they cannot achieve their goals, or when they profit from social exchanges. In this work we study coalition formation processes supported by enforced agreements and we define two qualitative criteria, the do-ut-des property and the composition property, that establish when a coalition is admissible to be formed. The do-ut-des property is based on a balance between the advantages and the burdens of an agent, when it agrees an enforced agreements. The composition property is a refinement of the do-ut-des property that takes into account also the costs and the risks deriving from the coalition formation process. Two relevant aspects distinguish our approach from the solution criteria developed in cooperative game theory. First, the do-ut-des property and the composition property are not based on an explicit utility function associated to the goals of an agent, and hance they can be used also in that cases in which the importance that agents give to their own goals is unknown. Second, a coalition has all the necessary information to establish if it satisfies the do-ut-des property or the composition property, therefore these two properties can be used in the case not all the space of possible coalitions is known. Luigi Sauro graduated in Physics at the University “Federico II” of Naples in 2001. From February 2002 to July 2002 he was collaborator at the SRA division of the IRST Institute (Trento). He got is Ph.D. in Computer Science from University of Torino in February 2006. Currently he is member of the Natural Language Processing and Agents Group, directed by prof. Leonardo Lesmo. His research interests include social reasoning, coalition formation and coordination in multiagent systems.