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Author(s): A. K. Pautova [sup.1] , N. A. Burnakova [sup.2] , N. V. Beloborodova [sup.1] , A. I. Revelsky [sup.2] Author Affiliations: (1) grid.513061.0, Federal Research and Clinical Center of [...], Aromatic, short-chain fatty and dicarboxylic acids are low-molecular-weight microbial and mitochondrial metabolites; therefore, their simultaneous screening in biological samples, including cerebrospinal fluid, is a promising solution to an important problem - the timely differential diagnosis of various diseases and pathologies, in particular, those associated with the disruption of the central nervous system. There is a need in developing a sensitive method for the simultaneous determination of these compounds, because they are most often present in biological samples in trace amounts. Blood serum and cerebrospinal fluid are complex matrices including various compounds. Aromatic, short-chain fatty and dicarboxylic acids were isolated and preconcentrated in the present study by traditional liquid-liquid extraction modified at the derivatization stage: the organic extractant was not evaporated and derivatization was carried out directly in the volume of diethyl ether. The different volatilities and polarities of the compounds was taken into account; therefore, derivatization was carried out with moderate heating (60°C) using various silylating reagents. Depending on the type of silyl derivatives, we set the analysis mode of gas chromatography-mass spectrometry method in order to achieve an acceptable analysis time, increase sensitivity to target compounds, and carry out a complete gas chromatographic separation of all analytes. To assess the applicability of the developed conditions, analytical characteristics were determined in model solutions and in the blood serum of healthy donors. For all the developed analysis conditions, linearity was observed in a clinically significant range; the lower limits of quantitation were in the range from 0.06 to 0.9 mol L.sup.-1, which made it possible to analyze samples of the cerebrospinal fluid of neurosurgical patients (n = 6).

Author(s): E. S. Markova [sup.1] , A. N. Furman [sup.1] , S. P. Shekhtman [sup.1] , A. V. Pirogov [sup.1] , M. V. Popik [sup.1] , O. A. Shpigun [sup.1] [...], A domestic composite material based on silicon carbide and nitrile butadiene rubber was used to identify volatile substances of banana, banana flavor, and creamy chewing candies by passive adsorption in combination with thermal desorption GC-MS. This method can be used to determine a wide range of compounds, for example, esters of carboxylic acids, terpenoids, aldehydes, aromatic hydrocarbons, alkanes, heterocyclic compounds, phenols, glycerides, and fatty acids. The obtained chromatographic profiles of the samples were compared. In the chromatogram of "Banana" flavor, five peaks (out of eight) corresponded to the compounds that form the aroma of a banana, and in the chromatogram of "Love is" candies with banana flavor, three corresponding peaks (out of 21) were found.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.solener.2008.08.004 Byline: Juliana Carla Garcia, Julliana Isabelle Simionato, Alessandra EugA*nio Carli da Silva, Jorge Nozaki, Nilson Evelazio de Souza Keywords: Textile effluents; Titanium dioxide; Hydrogen peroxide; Mineralization Abstract: The present work investigated the photodegradation of real textile effluents by advanced oxidative process (AOP) using TiO.sub.2/H.sub.2O.sub.2/sunlight system. The procedures were carried out at ambient conditions in March 2005. The results were evaluated by COD reduction concomitant to the increase in inorganic ion concentration (mineralization) and the analysis of the effluent characteristic spectral wavelengths: 228, 254, and 284nm (simple aromatic compounds), 310nm (conjugated aromatic compounds), and 390, 450, and 530 (color). As this study is not restricted to the decolorization process, it allows a more reliable evaluation of effluent mineralization. The results indicate that solar radiation is as efficient as or even more efficient than artificial radiation was in previous studies and that it also allows a reduction in effluent treatment operational costs. Author Affiliation: Department of Chemistry, Universidade Estadual de Maringa, Av. Colombo, 5790, CEP 87020-900, Maringa, PR, Brazil Article History: Received 31 March 2008; Revised 21 July 2008; Accepted 11 August 2008 Article Note: (miscellaneous) Communicated by: Associate Editor Gion Calzaferri

Pseudomonas putida CSV86 utilizes aromatic compounds in preference to glucose and coutilizes aromatics and organic acids. Protein analysis of cells grown on different carbon sources, either alone or in combination, revealed that a 43-kDa periplasmic-space protein was induced by glucose and repressed by aromatics and succinate. Two-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry analysis identified this protein as closely resembling the sugar ABC transporter of Pseudomonas putida KT2440. A partially purified 43-kDa protein showed glucose binding activity and was specific for glucose. The results demonstrate that the aromatic- and organic acid-mediated repression of a periplasmic-space glucose binding protein and consequent inhibition of glucose transport are responsible for this strain's ability to utilize aromatics and organic acids in preference to glucose.

The phenomenon under the name 'resonance,' which, is based on the mathematical analogy between mechanical resonance and the behavior of wave functions in quantum mechanical exchange phenomena was described. The resonating system does not have a structure intermediate between those involved in the resonance, but instead a structure which is further changed by the resonance stabilization.

The anaerobic degradation of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds with amorphous ferric oxide as electron acceptor was examined. The electron balances showed a complete anaerobic oxidation of the aromatic compounds to CO2.

The students in the introductory organic chemistry course at Iona College uses SPARTAN ES -02, a software package to study the concept of aromatic substitution. Details on how students use this software to help themselves learn the concept of substitution and how it has helped them in learning aromaticity are discussed.

Abstract -- The laws of the adsorption of aromatic compounds on the trialkylphosphine oxide-modified electrodes of a piezoelectric quartz resonator were studied. Differences in the time parameters of adsorption were [...]

The analysis indicates that the origin of enantioselectivity in the ring-closing metathesis of achiral trienes is correlated to the chiral folding of the N-bonded aromatic groups, which is imposed by the Ph groups in positions 4 and 5 of the imidazole ring of the N-heterocyclic(NHC) ligand. The mechanism of enantioselectivity in the asymmectric Ru-catalyzed metathesis of olefins is investigated with a theoretical approdach.

Byline: T.G. Schmalz (1), M.T. Pena (1), E.T. Morgenthaler (1) Keywords: conjugation; aromaticity; pi-electron theory; cluster expansions Abstract: There are two long established methods for representing the delocalized portion of the pi-electron energy of conjugated molecules in a simple local fashion. One, introduced by Hess and Schaad, can be used to provide a very accurate estimate of the energy of acyclic polyenes. Another, introduced originally by Herndon, has been successfully applied to the energy of aromatic ring systems. Both methods can be shown to be forms of cluster expansions, in which the energy of a molecule is expressed exactly as a sum of (successively smaller) contributions from successively larger molecular fragments. As such, it should in principle be possible to combine the methods to provide a consistent description of molecules of almost any structure. However past attempts to do so have yielded physically unreasonable results. It is shown that the key missing ingredient in these attempts is a failure to account for bond stretching and compression. When the energy changes associated with bond length changes are accounted for properly, the combined cluster expansion is quite successful in accounting for molecular pi electron energies in a very compact form. Author Affiliation: (1) Texas A&amp M University at Galveston, Galveston, TX, 77553-1675, USA Article History: Registration Date: 08/10/2004

For the first time, ion mobility spectrometers (IMS) with radioactive and UV ionization sources in combination with multicapillary columns (MCCs) have been used to determine methyl tert-butyl ether (MTBE), a gasoline additive, in water and nitrogen as well as the monoaromatic compounds benzene, toluene, and m-xylene (BTX). A membrane extraction unit was set up to extract the substances from water, which is simple, effective, and easy to automate for further applications. Thus, the detection of MTBE and BTX of gasoline vapors was accomplished after a preliminary silicone membrane extraction. Two-dimensional data analyses of IMS-chromatograms allow us to separate these substances clearly according to their different retention and drift times. Method detection limits for MTBE were 2 [micro]g/L (UV) and 30 pg/L ([sup.63]Ni) in nitrogen and 20 mg/L (UV) and 1 [micro]g/L ([sup.63]Ni) in water. Rather a good reproducibility was achieved with relative standard deviations of between 2.9 and 9%. The method presented in this article has been proven to be suitable for nearly real-time monitoring as the total analysis time is less than 90 s. As an example of application, the detection of MTBE and BTX in a mixture of volatile organic compounds of pure gasoline using the 2-D IMS-chromatogram is presented.

The analysis of alkylbenzothiophenes (alkyl-BT) and alkyldibenzothiophenes (alkyl-DBT) in light cycle oil (LCO) and straight run (SR) gas oils is described. A detailed identification and quantitative analysis of alkyl-BT and alkyl-DBT present in LCO gas oils was carried out using GC-SCD. For the SR gas oils, the simultaneous presence of thiophenic and nonthiophenic compounds does not allow for a selective analysis of thiophenic compounds by GC-SCD. A new method using gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS)is proposed to selectively detect and quantify the alkyl-BT and alkyl-DBT in SR gas oils. The development of the method and comparison of results between GC-SCD and GC-HRMS are presented.

The monoelectronic or cathodic reduction of hexakis(alkylsulfonyl) benzenes in aprotic solvent is investigated to determine the kinetic and thermodynamic constants associated with reduction phenomena, as a function of the alkyl substituents. A four-member square scheme for which the neutral and radical anion species can exist in both boat and chair conformers, are proposed based on electrochemical data supported by molecular modeling calculations like density functional theory (DFT) and semiempirical methods (PM3).

The interactions of trimeric perfluoro-ortho-phenylene mercury with biphenyl, naphthalene, and triphenylene are described. Results elucidate the structures and luminescent characteristics of the supramolecular stacks that are formed by the weak pi-complexation of the aromatic substrates to the mercury centers of trimeric perfluoro-ortho-phenylene mercury. Data indicate trimeric complexes exhibit affinity for aromatic substrates.

The ability of electrospray ionization mass spectrometry (ESI MS) to analyze heavy aromatic petroleum fractions using silver nitrate as a reagent compound to form characteristic adduct ions has been examined. The complexation of aromatic compounds containing long alkyl substituents with the silver ion leads to the formation of abundant adduct ions such as [[M + Ag].sup.+] and [[2M + Ag].sup.+]. The concentration of the [[2M + Ag].sup.+] ions can be reduced by increasing the sampling cone voltage. Molecular ions and other adduct ions may also be formed depending on the structure of the aromatic molecule. Results obtained from the analysis of representative heavy petroleum fractions and vacuum residues by the [Ag.sup.+] ESI MS method and conventional ionization methods were in good agreement. The current method extends the applicability of electrospray ionization to the analysis of neutral hydrocarbons in heavy aromatic petroleum fractions. It is simple and compatible with widely available LC/MS instrumentation. The extreme complexity of the [Ag.sup.+] ESI spectra will require the development of ultrahigh-resolution MS and MS/MS methods for the separation and elucidation of the structures in the vacuum residues.

Results reveal that the inner-sphere reorganization energy is influenced mainly by CN and NN bond lengths and the CNN bond angle. Further, the B3LYP/6-31G* level calculations are the most suitable for calculating inner-sphere reorganization energies for the single electron-transfer reaction between cation/neutral arenediazonium ion couples.

Results indicate that sulfinyl substitution in arenes decreases the fluorescence quantum yield without increasing the triplet yield. Racemization and nonradiative decay are closely associated with the singlet excited state. In aryl methyl sulfoxides, sulfur inversion quantum yield is as high as 0.8.

Results demonstrate the interphase polarity of the bimolecular aromatic nucleophilic substitution reactions between 1-fluoro-2,4-dinitrobenzene and piperidine in the anionic benzene/AOT/water and the cationic benzene/BHDC/water solvent systems. Data indicate that the distribution of reactants in the micelle interface is negligible in the anionic medium whereas in medium containing piperidine, a slight micellar effect is observed.

Results show that cyano-substituted carbon is critical for phototransposition in acetonitrile as revealed by dimethylbenzonitriles reaction mechanism. Data indicate that the excited nitrile combines with abicyclo[3.1.0]-hexenyl biradical with a sigma bond formed between the two carbons at ortho position to the functional nitrile group.

Results demonstrate Diels-Alder reactions of quinodimethanes with C(sub)60 with reference to their aromaticity effects. Data point out that the degree of aromatization increases with increases in quinodimethane-fullerene reaction rate and exothermicity.

Based upon the magnetic properties, geometries, triplet-singlet energy differences, and stability characteristics 7-carbenanorbornene and 3-carbenabicyclo[3.1.0]hexane are determined to be homoaromatic and 2-carbenabicyclooctadiene antihomoaromatic.

Research has been conducted on the white-rot fungus Pleurotus ostreatus. The ability of this fungus to degrade polycyclic aromatic hydrocarbons has been investigated.

Results demonstrate that the NO(sub)2(sup)+ nitration of an aromatic compound 1,8-dimethylnaphthalene follows an electrophilic as well as a direct charge-transfer process. The other reactions occurring during the process are ipso attack of NO(sub)2(sup)+, the 1,2-shift of the NO(sub)2 group, and an alternative charge-transfer reaction.

Research has been conducted on the aromatic sulfonates from Pseudumonas putida S-313. Strain S-313 mutants have been isolated and found to carry transposon insertions in the ssuEADCBF operon.

Research has been conducted on the Pt (super)II (L-L')(dppm) (super)n+ complexes. The structural characteristics of these complexes are presented.

The synthesis of heterodisubstituted p-carboranes proceeds via triphenylsilyl-p-carborane, which serve as intermediary products for the preparation of liquid crystalline materials. Data reveal that p-carborane can be converted into its lithium and copper derivatives, which react with alkyl halides, such as an aryl , an acetylene bromide, and a sulfenyl chloride.

Research has been conducted on the iridium(III) nitrosyl complex. Reactions of the complex with hydrosulfide and arenethiolate anions have been investigated.

Research has been conducted on the phenylthioheptane and phenylthiononane synthesis. Results indicate that their conformations have been studied in a solid state and in solutions.

Research has been conducted on the reaction of symmetrically hindered methylphenols with NBS. The formation of the transient intermediates that produce hydroxybenzaldehydes is discussed.

The electronic and vibrational relaxation of tetracene were investigated in solution by femtosecond time-resolved fluorescence spectroscopy. Tetracene was initially photoexcited to the highly excited singlet (Sn) state 1Bb, and the dynamics of the fluorescence from the 1Bb state and the 1La state (S1) were studied by fluorescence up-conversion. Different kinds of fluorescence/anisotropy dynamics were seen from the femtosecond to the picosecond time region, which reflect a series of the relaxation processes occurring in the molecule after photoexcitation.

A study was conducted to analyze the intrinsic reactivity of a 1,3-dehydrobenzene supporting a pyridinium charge site in the 5-position. Fourier transform ion cyclotron mass spectrometry was utilized to carry out the analysis. The m-benzyne was produced using a combination of ion-molecular reactions and photodissociation. Results indicated distinct properties that differ from those of related monoradical and isomeric o-benzyne.

We have examined p-tert-butylcalix[4]arenetetrathiolate (BCAT) monolayers for their potential use as molecular recognition elements for in situ aqueous chemical sensors. Spectroscopic and wetting studies of BCAT monolayers on Au{111} reveal that the calixarene molecules exist in monolayers, preferentially oriented with their phenyl rings parallel to the surface normal axis. Using quartz crystal microbalance (QCM) sensors with gold-coated electrodes, the chemical specificity of monolayers and thin films to a variety of aromatic and aliphatic analytes in aqueous solution was examined. The response of BCAT sensors was compared to the responses of p-tertbutylcalix[4]arene (BCA)- and decanethiolate (DT)-coated QCM electrodes. BCAT is very selective for alkylbenzenes, much more so than either its spray-coated thin-film analogue, BCA, or the highly ordered DT monolayer. From these measurements, the factors behind molecular differentiation in each film are explored. Drawing upon these findings, the roles of cavitation and film order in molecular recognition for calixarene films are discussed.

A study on the use of (N'N-dimethylcarbamoyl)methyl-substituted calix(4) arenes as selective extractants is presented. These calixarenes have been selected because of their ability to preorganize with metal ions at multiple sites that can accept ligating functional groups. (Methylthio)methyl derivatives have been used instead of thiolates because they have a higher selectivity for heavy metal ions.

The efficient syntheses of secondary and tertiary 2-aryl- and 2-heteroaryl-allyl alcohols have been undertaken. The alcohols are products of the reactions between ketones and aldehydes with alpha-aryl, alpha-heteroaryl and alpha-heteroatom-substituted masked alkenyllithiums. An aryl or heteroaryl has been substituted at the beta position and aryl, heteroaryl or alkyl substituents in the alpha position via a (1,4)-C-->O silicon rearrangement. The allylic alcohols form stable trimethylsilyl ethers and cleave at the O-Si bond under basic or acidic conditions.

The contention between electron transfer (ET) and triplet energy transfer (TT) in the quenching of benzophenone, xanthene and anthraquinone in the triplet state by molecules with both a sufficiently small oxidation potential and low triplet state was examined in the picosecond to microsecond time scales. During the longer time scale, the product distribution had a strong dependence on the relative exogenicity of ET and TT processes. Picosecond transient grating measurements showed that if TT is more exogenic than ET, then the TT product is mostly formed by two sequential ET reactions.

Laser multiphoton ionization (LMPI) and laser-induced fluorescence (LIF) techniques were simultaneously applied to analysis of polycyclic aromatic hydrocarbons (PAH) in apolar solution. This combination of single-photon (LIF) and multiphoton (LMPI) processes provides unique information which is shown to be sufficient for both identification and quantification of PAH molecules in simple mixtures. We suggest 3D calibration plots (concentration as a function of both LMPI and LIF signals) where each PAH compound is represented by a unique vector in this space. The projections of such vectors onto the LMPI-LIF plane are the basis of PAH analysis, where only two measurements (LMPI and LIF signals) are required for speciation and quantification of a single component. A geometrical algorithm for decomposition of simple PAH mixtures, is also addressed.

Ab initio techniques to calculate nuclear shieldings and deuterium isotope influences on nuclear shieldings have evolved to a high degree of accuracy. A study was conducted involving ab initio calculations to show, namely, that deuterium isotope effect on chemical shifts is a quantitative descriptor of hydrogen bond strength, how these data are calculated theoretically and that reliable structures can be obtained and very good 1H and 13C chemical shifts can be calculated in intramolecularly hydrogen-bonded cases.

The complex TpRe(CO)2 binds with aromatic compounds and forms binuclear complexes of the form (TpRe(CO)(sub 2))(sub 2)(mu-eta(super 2)-eta(super 2')-L) where L = furan, N-methylpyrrole or naphthalene. The furan-bridged complex is the result of a transient eta(super 2)-furan monomeric complex. The transient monomeric complex could also be the reason for the formation of the two other complexes. However, the electron density at the metal center is diminished by the presence of two carbonyl ligands.