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In developing methods for the preliminary chemical modification of nonpolar sulfur-containing compounds for their subsequent effective study by "soft" ionization [electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI)] mass spectrometry, a rather unexpected possibility of implementing S-alkylation of analytes with polydialkylsiloxanes in the presence of trifluoromethanesulfonic acid (CF.sub.3SO.sub.3H) as a superacid co-alkylating agent has been found. The ESI and MALDI mass spectra show that the corresponding S-alkylsulfonium salts are formed in both cases. However, in using polydimethylsiloxane, it is not possible to choose reaction conditions that would provide reproducible product yields. At the same time, in the case of polydiethylsiloxane, the reaction proceeds with an almost quantitative yield, regardless of the structure of the initial thiabicycloalkane. Subsequent studies of derivatization products are best performed using MALDI mass spectrometry, which allows the detection of target signals with high signal-to-noise ratios. In the case of ESI, the spectra are sometimes noticeably noisy with extraneous peaks, obviously due to hydrolysis and condensation products. A rational mechanism of the described chemical transformation is proposed, including indispensable activation by the trifluoromethanesulfonic acid accompanied by the rupture of the Si-C bond and the release of an alkyl cation modifying the sulfide. The effects of the structure and regio-isomerism on the collision-activated dissociation mass spectra of S-ethylated bicyclic sulfonic cations are considered., Author(s): J. E. Starkova [sup.1] , V. V. Ilyushenkova [sup.2] , N. Yu. Polovkov [sup.1] , A. Yu. Kanateva [sup.1] , R. S. Borisov [sup.1] [sup.3] [sup.4] [sup.5] , V. [...]

Atomic-deficient nanostructurization in composites based on arsenic sulfide [As.sub.4][S.sub.4] polymorphs, such as (1) [beta]-[As.sub.4][S.sub.4], (2) realgar [alpha]-[As.sub.4][S.sub.4], and (3) mixture of realgar, pararealgar, and intermediate [chi]-phase subjected to high-energy mechanochemical milling in polyvinylpyrrolidone (PVP) solution, are studied exploring the method of positron annihilation lifetime spectroscopy. Positron lifetime spectra reconstructed from unconstrained x3-term fitting procedure testify in a favor of mixed positron-positronium trapping in the studied composites. Modified x3-x2-coupling decomposition algorithm is applied to parameterize expected annihilation channels in [As.sub.4][S.sub.4]-PVP nanocomposites in respect to PVP matrix. Interfacial free-volume voids between nanoparticles composed of arsenic sulfide crystallites embedded in PVP environment are defined as most favorable positron trapping sites, loosely packed in respect to variety of crystallographic polymorphs used for milling., INTRODUCTION The promising anticancer functionality of arsenic sulfide [As.sub.4][S.sub.4] polymorphs has been in a sphere of tight interests in biomedicine because of versatile angiogenesis inhibition effect on a row of [...]

The critical, and often most difficult, step in structure elucidation of diverse classes of natural peptides is the determination of correct disulfide pairing between multiple cysteine residues. Here, we present a direct mass spectrometric analytical methodology for the determination of disulfide pairing. Protonated peptides, having multiple disulfide bonds, fragmented under collision induced dissociation (CID) conditions and preferentially cleave along die peptide backbone, with occasional disulfide fragmentation either by [C.sup.[beta]]-S bond cleavage through [H.sup.[alpha]] abstraction to yield dehydroaianine and cysteinepersultide, or by S-S bond cleavage through [H.sup.[beta]] abstraction to yield the thioaldehyde and cysteine. Further fragmentation of the initial set of product ions ([MS.sub.n]) yields third and fourth generation fragment ions, permitting a distinction between the various possible disulfide bonded structures. This approach is illustrated by establishing cysteine pairing patterns in five conotoxins containing two disulfide bonds. The methodology is extended to the Conus araneosus peptides Ar1446 and Ar1430, two 14 residue sequences containing 3 disulfide bonds. A distinction between 15 possible disulfide pairing schemes becomes possible using direct mass spectral fragmentation of the native peptides together with fragmentation of enzymatically nicked peptides. 10.1021/ac101867e

The Magneli phase [Ti.sub.4][O.sub.7] (Ebonex®) was used as both anode and cathode in the electrochemical oxidation of sulfide ion in alkaline solution in the absence and presence of chloride and naphthenate ions. Ebonex anodes gradually lost their activity through the formation of an over-oxidized surface layer, but their activity could be maintained by periodic polarity reversal. In the context of the current paradigm for the mechanistic behaviour of oxide-based anodes, [Ti.sub.4][O.sub.7] has properties that combine those of 'inactive' anodes (formation of hydroxyl radicals) and 'active' anodes (formation of a higher oxide at the surface), with the exception that the higher oxide in the case of [Ti.sub.4][O.sub.7] is Ti[O.sub.2], which is incapable of substrate oxidation. Sulfate is the major oxidation product, especially in the presence of chloride, an ubiquitous component of sour brines, via mediated electro-oxidation to hypochlorite. Unlike at boron-doped diamond anodes, at which sulfide is oxidized with near-quantitative current efficiency, significant parasitic oxidation of water to [O.sub.2] occurs at Ebonex, and oxidation of sulfide requires ~16 F [mol.sup.-1], corresponding to a 50% current efficiency. Key words: geothermal sour brines, electrochemical oxidation of sulfide, Magneli phase [Ti.sub.4][O.sub.7], hydroxyl radicals. La phase Magneli du [Ti.sub.4][O.sub.7] (Ebonex®)aete utilisee tant comme anode que comme cathode dans l'oxydation electrochimique de l'ion sulfure en solution alcaline, en l'absence et en presence d'ions chlorure et naphteenate. Les anodes d'Ebonex perdent graduellement leur activite en raison de la formation d'une couche superficielle suroxydee; toutefois, leur activite; peut etre maintenue par un renversement periodique de polarite. Dans le contexte du paradigme actuel pour le comportement mecanistique des anodes a base d'oxydes, le [Ti.sub.4][O.sub.7] possede des proprietees qui combinent celles des anodes <> (formation de radicaux hydroxyles) et celles des anodes <> (formation a la surface d'un oxyde plus eleve); toutefois, dans le cas du [Ti.sub.4][O.sub.7], l'oxyde plus elevee est le Ti[O.sub.2] qui est incapable de donner lieu a une oxydation du substrat. Le sulfate est le produit d'oxydation majeur, particulierement en presence de l'ion chlorure, un composant normal de toutes les saumures acides obtenu par l'electrooxydation en hypochlorite. Contrairement aux anodes de diamant dopees au bore avec lesquelles le sulfure est oxyde avec une efficacite de courant pratiquement quantitative, l'Ebonex donne lieu a une oxydation parasite importante de l'eau en [O.sub.2] et l'oxydation du sulfure requiert environ 16 F [mol.sup.-1], ce qui correspond a une efficacite; de courant d'environ 50%. Mots-cles: saumures acides geeothermiques, oxydation electrochimique du sulfure, phase Magneli du TUO7, radicaux hydroxyles., Introduction Geothermal 'sour brines' that accompany natural-gas extraction contain inorganic sulfide at concentrations up to ~60 mmol [L.sup.-1] and have pH ~8. (1) Volatilization of hydrogen sulfide ([pK.sub.a1] = 6.88, [...]

Recombinant monoclonal antibodies are an important class of therapeutic agents that have found widespread use for the treatment of many human diseases. Here, we have examined the utility of ion mobility mass spectrometry (IMMS) for the rapid characterization of disulfide variants in intact IgG2 monoclonal antibodies. It is shown that IMMS reveals 2 to 3 gas-phase conformer populations for IgG2s. In contrast, a single gas-phase conformer is revealed using IMMS for both an IgG1 antibody and a Cys-232 [right arrow] Ser mutant IgG2, both of which are homogeneous with respect to disulfide bonding. This provides strong evidence that the observed IgG2 gas-phase conformers are related to disulfide bond heterogeneity. Additionally, IMMS analysis of redox enriched disulfide isoforms allows assignment of the mobility peaks to established disulfide bonding patterns. These data clearly illustrate how IMMS can be used to quickly provide information on the higher order structure of antibody therapeutics. 10.1021/ac1013139

A novel analytical method for identifying sulfides in petroleum and its fractions was developed. Sulfides in petroleum were selectively oxidized into sulfoxides using tetrabutylammonium periodate (TBAPI) and identified by positive-ion electrospray ionization (ESI) Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). A variety of model sulfur compounds were examined to evaluate the selective oxidization and ionization efficiencies for sulfur compounds in petroleum. Two fractions, straight-run diesel and saturates of Athabasca oilsands bitumen were investigated using this approach. The oxidization process was highly selective for sulfides from thiophenes and aromatic hydrocarbons. Oxidation generated sulfoxides were ionized by positive-ion ESI and analyzed by FT-ICR MS. Mass spectra revealed the composition characteristics of sulfides in the diesel by contrasting the double bond equivalence (DBE) and carbon number distribution of sulfur compounds before and after oxidation. The abundant sulfides in the straight run diesel and saturates fraction of oilsands bitumen had DBE values of 1-3 and 1-4, respectively. 10.1021/ac1010553

Cleavage of the disulfide bond within a polypeptide was observed when the nanoelectrospray (nanoESI) plume of a peptide solution interacted with a low-temperature helium plasma in air. Online mass spectrometric analysis revealed that chain separation accompanied by a mass increase of 1 or 16 Da for each chain was common to peptides having an interchain disulfide bond, while for peptides having intrachain disulfide bonds, the reaction products typically showed mass increases of 17 Da. Experimental results suggested that hydroxyl radicals initiated from the plasma were likely to be responsible via dissociative addition to the disulfide bond (RSSR'), giving rise to RSH and R'[SO.sup.*]. When the hydroxyl radical addition product ions ([[M + nH + OH].sup.n*+], n is the charge state) generated from peptides having intra-chain peptides were subjected to collision-induced dissociation (CID) in an ion trap, a-, b-, and y-type sequence ions within the cyclic structure defined by the disulfide bond were observed in addition to the exocyclic cleavages typically seen from CID of[ [M + nH].sup.n+] peptide ions. Rich structural information could thus be obtained. These findings were demonstrated in 14 peptides containing disulfide bonds and further by bovine insulin, which has three disulfide bonds. Collisional activation of the [[M + 5H + OH].sup.5*+] insulin ions provided 76% of the possible backbone cleavages as compared to 26% acquired from CID of the[ [M + 5H].sup.5+] ions. 10.1021/ac9028328

Byline: Claudio Marchesi (1,2), William L. Griffin (2), Carlos J. Garrido (3), Jean-Louis Bodinier (1), Suzanne Y. O'Reilly (2), Norman J. Pearson (2) Keywords: Subcontinental lithospheric mantle; Partial melting; Proterozoic; Re--Os isotopes; Sulfide; Ronda massif Abstract: The western part of the Ronda peridotite massif (Southern Spain) consists mainly of highly foliated spinel-peridotite tectonites and undeformed granular peridotites that are separated by a recrystallization front. The spinel tectonites are interpreted as volumes of ancient subcontinental lithospheric mantle and the granular peridotites as a portion of subcontinental lithospheric mantle that underwent partial melting and pervasive percolation of basaltic melts induced by Cenozoic asthenospheric upwelling. The Re--Os isotopic signature of sulfides from the granular domain and the recrystallization front mostly coincides with that of grains in the spinel tectonites. This indicates that the Re--Os radiometric system in sulfides was highly resistant to partial melting and percolation of melts induced by Cenozoic lithospheric thermal erosion. The Re--Os isotopic systematics of sulfides in the Ronda peridotites thus mostly conserve the geochemical memory of ancient magmatic events in the subcontinental lithospheric mantle. Os model ages record two Proterozoic melting episodes at ~1.6 to 1.8 and 1.2--1.4 Ga, respectively. The emplacement of the massif into the subcontinental lithospheric mantle probably coincided with one of these depletion events. A later metasomatic episode caused the precipitation of a new generation of sulfides at ~0.7 to 0.9 Ga. These Proterozoic Os model ages are consistent with results obtained for several mantle suites in Central/Western Europe and Northern Africa as well as with the Nd model ages of the continental crust of these regions. This suggests that the events recorded in mantle sulfides of the Ronda peridotites reflect different stages of generation of the continental crust in the ancient Gondwana supercontinent. Author Affiliation: (1) Geosciences Montpellier, UMR 5243, CC 60, CNRS-Universite Montpellier II, Place E. Bataillon, 34095, Montpellier, France (2) GEMOC ARC National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW 2109, Australia (3) Instituto Andaluz de Ciencias de la Tierra (IACT), CSIC-Universidad de Granada, Avenida Fuentenueva s/n, 18002, Granada, Spain Article History: Registration Date: 13/07/2009 Received Date: 02/02/2009 Accepted Date: 13/07/2009 Online Date: 14/08/2009 Article note: Communicated by J. Hoefs.

We have investigated if in a cold seep methane or sulfide is used for chemosynthetic primary production and if significant amounts of the sulfide produced by anaerobic oxidation of methane are oxidized geochemically and hence are not available for chemosynthetic production. Geochemically controlled redox reactions and biological turnover were compared in different habitats of the Hakon Mosby Mud Volcano. The center of the mud volcano is characterized by the highest fluid flow, and most primary production by the microbial community depends on oxidation of methane. The small amount of sulfide produced is oxidized geochemically with oxygen or is precipitated with dissolved iron. In the medium flow peripheral Beggiatoa habitat sulfide is largely oxidized biologically. The oxygen and nitrate supply is high enough that Beggiatoa can oxidize the sulfide completely, and chemical sulfide oxidation or precipitation is not important. An internally stored nitrate reservoir with average concentrations of 110 mmol [L.sup.-1] enables the Beggiatoa to oxidize sulfide anaerobically. The pH profile indicates sequential sulfide oxidation with elemental sulfur as an intermediate. Gray thiotrophic mats associated with perturbed sediments showed a high heterogeneity in sulfate turnover and high sulfide fluxes, balanced by the opposing oxygen and nitrate fluxes so that biological oxidation dominates over geochemical sulfide removal processes. The three habitats indicate substantial small-scale variability in carbon fixation pathways, either through direct biological use of methane or through indirect carbon fixation of methane-derived carbon dioxide by chemolithotrophic sulfide oxidation.

The detection and characterization of unexpected disulfide-mediated structural variants of human immunoglobulin G2 (IgG2) antibodies was recently the subject of two copublications. In this paper, we present data to confirm the previously reported structures and elucidate the complete disulfide connectivity of each variant through the application of a novel analytical methodology. In this manner, the data illustrate the presence of at least five structural variants, including the classical structure with independent Fab domains and a hinge region. Multiple subvariants of the IgG2-A/B and IgG2-B structures are identified; these subvariants of each structure differ through the order of attachment of Fab peptides to the sequential hinge cysteines. Furthermore, the connectivity of a novel subvariant of IgG2-B containing an intraehain disulfide linkage in the lower hinge region is elucidated. The results presented in this paper reveal that the population of IgG2 disulfide structural variants is yet more complex than recently reported. 10.1021/ac902466z

Detailed mapping of a portion of the North Spirit Lake greenstone belt reveals a basal basaltic volcanic unit (ca. 3 Ga) with a komatiitic component and strong major and trace element geochemical affinity with typical mid-ocean ridge basalts (e.g., N-MORB). The overlying transitional unit includes basaltic tufts, which have close geochemical affinity to the underlying basalts, and to N-MORB. Interbedded with and overlying the tufts is a thin, laterally continuous sulfide-rich unit with chert interbeds, which is in turn over-lain by interbedded carbonate, chert, and iron-rich sedimentary rocks. The chemical sedimentary rocks of the transitional unit display rare-earth element (REE) patterns and positive Eu anomalies consistent with derivation from fluids associated with submarine hydrothermai vent fields. The sulfide unit is interpreted to represent proximal hydrothermal vent deposits derived from black smoker activity near a spreading center. The overlying carbonate and chert mounds and beds are interpreted as hydrothermal deposits formed at lower temperatures in a more distal setting relative to the spreading center. The carbonate deposits may have formed in an environment analogous to that of the Lost City hydrothermai field (Kelley et al., 2001), where abundant chimneys, dendrites, and beds of carbonate are produced ~15 km from the mid-Atlantic rift axis. The basal volcanic unit consequently is interpreted as ocean-floor basalts formed at an Archean spreading center, with the basaltic tufts representing the last volcanic emanations, and with the chemical sediments representing hydrothermalvents deposits both proximal and distal to the spreading center. The capping siliciclastic unit likely is part of an accretionary wedge, possibly representing ocean closure after a protracted seafloor speading episode. The sedimentary rocks were derived in part, from a weathered tonalite-trondhjemite-granodiorite source. The supracrustal rocks of the North Spirit Lake greenstone belt provide an unusually clear window into some tectonic activity on the primitive Earth, including evidence for the existence of ocean-floor basalts, proximal and distal hydrothermal activity, and possibly a protracted cycle of ocean opening and destruction.

We hypothesized that CaC[O.sub.3] dissolution, coupled to sulfide oxidation, is an important mechanism by which solid-phase inorganic P (iP) becomes available to seagrass in tropical carbonate sediments. To examine this supposition, we measured field sulfate reduction rates and simulated the acidity (10-50 [micro]mol [H.sub.2]S[O.sub.4] [cm.sup.-3] sediment) generated by subsequent sulfide oxidation from high (western) and low (eastern) total P (TP) sediments in Florida Bay. Dissolution experiments were conducted using sediment slurries at field pH (pore-water pH ~6.5-7.5). While CaC[O.sub.3] dissolution (maximum 1.3% of sediment dry weight) was evidenced at all sites by leaching of [Ca.sup.2+] into slurries, at three of the four sites P[O.sup.3-.sub.4] was primarily recovered in the sediment exchangeable pools and at a lower P:Ca ratio than observed in source sediments. In contrast, no P[O.sup.3-.sub.4] was recovered from an eastern bay site with the lowest TP and finest-grained sediments, suggesting that P[O.sup.3-.sub.4] was either tightly adsorbed or incorporated into the carbonate matrix post-acidification. The potential for tight P[O.sup.3-.sub.4] resorption by sediment from the low-TP site was also supported by the rapid rate of isotopic exchange of [sup.33] P[O.sup.3-.sub.4] into the sediment matrix. These adsorptive and incorporation processes may explain the low P[O.sup.3-.sub.4] in pore waters in the eastern vs. western regions of Florida Bay, even upon dissolution of carbonates. Carbonate dissolution coupled to sulfide oxidation could potentially provide 1.8 and 23.5 [micro]mol iP [m.sup.-2] [d.sup.-1] at eastern and western bay sites, respectively, meeting 5% of eastern and 29% of western bay seagrass (Thalassia testudinum) P requirements.

We present a novel approach for the assignment of peptides containing disulfide linkages. Dimethyl labeling is introduced to generate labeled peptides which exhibit enhanced al ion signals during MS/MS fragmentation. For disulfide-linked peptides, multiple al ions can be observed due to multiple N-termini. This distinct feature allows sieving out the disulfide-linked peptides; meanwhile, the N-terminal amino acids can be identified. With such information, the number of possible peptide combinations involved in a disulfide bond dramatically narrows down. Furthermore, we developed a computational algorithm to perform target al ion screening followed by molecular weight matching of cysteine-containing peptides with specific amino acids at the N-termini. Once the protein sequence and the peak list from a LC-MS/MS survey scan of labeled peptides are imported, the identities of disulfide-linked peptides can be readily obtained. The presented approach is simple and straightforward, offering a valuable tool for protein structural characterization.

The morphology of magmatic sulfides in igneous cumulates is controlled by the wetting properties of sulfide liquids against silicates. The formation of nickel sulfide ores, the behavior of sulfide liquids during mantle melting, and potentially the segregation of the Earth's core, are all controlled by the ability of sulfide liquids to migrate through the pore space of partially molten silicates. Three-dimensional X-ray tomographic images of sulfide aggregates in komatiitic olivine cumulates indicate that sulfide liquids have a limited tendency to wet olivine crystals, forming interconnected networks only in the absence of silicate melt. Consequently, the ability of sulfide liquids to migrate through the pore space of olivine cumulates is limited. We conclude that disseminated sulfide ores in komatiites formed by accumulation of transported sulfide blebs a few millimeters in size, and not by settling of sulfide-olivine aggregates, and that sulfides accumulated in the proportions in which they are now found, rather than by percolation through cumulate pore space. It is unlikely that sulfide droplets can be entrained and carried from the mantle at low degrees of partial melting. Our results also support the hypothesis that segregation of the Earth's core took place from a magma ocean, rather than by percolation of sulfidic melt through partially molten mantle. Keywords: magmatic sulfides, computed tomography, melt percolation, nickel sulfides.

We predict by first principles a phase transition in alumina at [approximately equal to]3.7 Mbar and room temperature from the Calr[O.sub.3]-type polymorph to another with the [U.sub.2][S.sub.3]-type structure. Because alumina is used as window material in shock-wave experiments, this transformation should be important for the analysis of shock data in this pressure range. Comparison of our results on all high-pressure phases of alumina with shock data suggests the presence of two phase transitions in shock experiments: the corundum to [Rh.sub.2][O.sub.3](11)-type structure and the [Rh.sub.2][O.sub.3](11)-type to Calr[O.sub.3]-type structure. The transformation to the [U.sub.2][S.sub.3]-type polymorph is in the pressure range reached in the mantle of recently discovered terrestrial exoplanets and suggests that the multi-megabar crystal chemistry of planetforming minerals might be related to that of the rare-earth sulfides. alumina | first-principles calculation | high-pressure phase transition | postperovskite | rare-earth sulfide structure

[Mn.sup.2+]-doped ZnS nanocrystals with an amine-capping layer have been synthesized and used for the fluorescence detection of ultratrace 2,4,6-trinitrotoluene (TNT) by quenching the strong orange [Mn.sup.2+] photoluminescence. The organic amine-capped nanocrystals can bind TNT species from solution and atmosphere by the acid base pairing interaction between electron-rich amino ligands and electron-deficient aromatic rings. The resultant TNT anions bound onto the amino monolayer can efficiently quench the [Mn.sup.2+] photoluminescence through the electron transfer from the conductive band of ZnS to the lowest unoccupied molecular orbital (LUMO) of TNT anions. The amino ligands provide an amplified response to the binding events of nitroaromatic compounds by the 2- to ~5-fold increase in quenching constants. Moreover, a large difference in quenching efficiency was observed for different types of nitroaromatic analytes, dependent on the affinity of nitro analytes to the amino monolayer and their electron-acceptlng abilities. The amine-capped nanocrystals can sensitively detect down to 1 nM TNT in solution or several parts-per-billion of TNT vapor in atmosphere. The ion-doped nanocrystal sensors reported here show a remarkable air/solution stability, high quantum yield, and strong analyte affinity and, therefore, are well-suited for detecting the ultratrace TNT and distinguishing different nitro compounds.

Mechanisms involved in stabilization of sulfide radical cations through complexation with the peptide bond are described. It is proved that the one electron oxidation by [super .]OH radicals of a simple dipeptide containing two methionine residues leads to efficient formation of the Met(S..N) radicals.

Effects of iron on the kinetics and stoichiometry of aerobic chemical sulfide oxidation in wastewater from two different sites were studied at pH 8 and 20[degrees]C. Iron(III) chloride was added to the wastewater in concentrations of up to 20 g Fe [m.sup.-3]. The rate of aerobic chemical sulfide oxidation increased linearly with the iron(III) additions resulting in equal effects with wastewater from the two sites. Despite the significant effect of the iron(III) additions, the background concentrations of iron cannot explain the significant temporal and spatial variability of aerobic chemical sulfide oxidation kinetics reported in this study and in the literature. In this respect, other metals are probably also important. In addition to the impacts on the oxidation kinetics, the iron(III) additions resulted in a change of the oxidation stoichiometry. With increasing amounts of iron(III) added to the wastewater, less dissolved oxygen was required for the sulfide oxidation. DOI: 10.1061/(ASCE)0733-9372(2007)133:6(655) CE Database subject headings: Iron; Oxidation; Wastewater management; Sewers.

The role of NaOH concentration on the oriented attachment growth kinetics was studied by investigating the crystal growth kinetics of ZnS nanoparticles coarsened less than 100 degree Celsius with NaOH concentration from 2 to 8 M. The findings suggest that the concentration of solute is very important for enhancing the oriented attachment growth rate and achieve exclusively oriented attachment growth of nanoparticles at a large size scale.

The research presents the synthesis, structure, electrical and physical properties of the polar oxysulfide CaZnOS. The compound is found to exhibit a non-phase-matchable second harmonic generation, as it is ferroelectric and contains very small pyroelectric coefficient between the room temperature and the boiling point of water.

A general and effective one-step procedure is presented for the synthesis of [beta]-sulfonamidodisulfides directly from N-tosyl aziridines in a regio- and stereospecific manner under neutral conditions and without using any Lewis acid or base. A number of [beta]-sulfonamidosulfides are synthesized in tandem, multistep reactions.

A research shows that compounds like disulfide S-monoxide (DSMO) and disulfide S-dioxide (DSDO) act as proximal mediators for the modification of various proteins, which is mediated by several oxidants. The analysis of the model of the protein kinase C (PKC) shows that the disulfide S-oxides (DSOs) from different thiols and oxidative states have completely different effects on the protein and can even cause distinct cellular responses on being derived from several cellular reactions.

High boiling solvent process was used to synthesize high quality ZnS, ZnS:[Mn.sup.2+], and ZnS:[Mn.sup.2+]/ZnS (core/shell) luminescent nanocrystals (NCs) and they were characterized by different spectroscopic methods. Highly monodisperse ZnS NCs were obtained by adding poly(ethylene glycol) to the reaction system and these ZnS NCs can be self-assembled into closely packed ultra-large range 2D arrays on the carbon-coated Cu grid.

Four Ser/Ala -> cys mutations at position 9, 42, 69 and 89 in human wild-type [alpha]Syn (wt-[alpha]Syn) and two PD-associated [alpha]Syn mutants, A30P-[alpha]Syn and A53T-[alpha]Syn is presented. The results reveal that under physiological conditions human [alpha]Syn exists as diverse conformational isomers, which exhibit distinct propensities for aggregation and fibril formation.

A bivariale population balance equation (PBE) model is developed and combined with new Monte Carlo (MC) simulations to study and predict the nanoparticle size distribution synthesized by mixing two water-in-oil reactive microemulsions solutions. The analysis proves to be extremely helpful in observing the mean aggregate number (MAN), as well as the size of the CdS nanoparticles and shows that MAN largely varies with the concentration and the microemulsion drop size of the nanoparticles.

A study of the dissociation mechanism of the S-S bond in the [alpha],[alpha']-dinaphthyl disulfide radical anion (NpSSNp.-) in organic solution on the bases of transient absorption measurements and DFT calculations is presented. It was seen that NpSSNp.- undergoes S-S bond cleavage to form NpS and Np[S.sup.-] with a first-order rate constant in the magnitude of [10.sup.6][s.sup.-1] in solution at room temperature.

Reactions of Ln[X.sub.3] and U[Cl.sub.4] with the alkali metal salts of the [[SPS.sup.Me].sup.-] anion give the first f-element complexes bearing an SPS-phosphinine-based pincer ligand. It is showed that the flexible tridentate [[SPS.sup.Me].sup.-] anion is bound to the metal as a tertiary phosphine with electronic delocalization within the unsaturated parts of the ligand.

Solid-state NMR spectroscopy was used to determine the conformation and membrane topology of the disulfide-stabilized antimicrobial peptide tachyplesin I (TP) in lipid layers. Results reveal that TP is immersed in the glycerol backbone region of the membrane and is oriented roughly parallel to the plane of the membrane.

A study synthesizes the model system of the hydrotreating catalyst consisting of Mo[S.sub.2] nanoclusters supported on a graphite surface in order to resolve some fundamental questions related to the atomic-scale structure and morphology of the active clusters, particularly the effect of a substrate used in some types of hydrotreating catalysts. The synthesized Mo[S.sub.2] nanoclusters are found to display a very temperature-dependent morphology, since clusters prepared at 1000 K grow as single-layer clusters, whereas clusters prepared at 1200 K exclusively grow as stacked multilayer clusters.

A study was conducted to observe the quenching effect of the photoluminescence of 1,2,4,5-tetrakis(4-pyridylvinyl)benzene in the presence of CdS colloids stabilized by inverse micelles. An increase in the two-photon absorption cross section and in the two-photon-induced fluorescence intensity was observed for the composite solution when pumped by 740-nm laser irradiation.

Fast mapping of disulfide bonds in proteins containing multiple cysteine residues is often required in order to assess the integrity of the tertiary structure of proteins prone to degradation and misfolding or to detect distinct intermediate states generated in the course of oxidative folding. A new method of rapid detection and identification of disulfide-linked peptides in complex proteolytic mixtures utilizes the tendency of collision-activated peptide ions to lose preferentially side chains of select amino acids in the negative ion mode. Cleavages of cysteine side chains result in efficient dissociation of disulfide bonds and produce characteristic signatures in the fragment ion mass spectra. While cleavages of other side chains result in insignificant loss of mass and full retention of the peptide ion charge, dissociation of external disulfide bonds results in physical separation of two peptides and, therefore, significant changes of both mass and charge of fragment ions relative to the precursor ion. This feature allows the fragment ions generated by dissociation of external disulfide bonds to be easily detected and identified even if multiple precursor ions are activated simultaneously. Such broadband selection of precursor ions for consecutive activation is achieved by lowering the dc/rf amplitude ratio in the first quadrupole filter of a hybrid quadrupole time-of-flight mass spectrometer. The feasibility of the new method is demonstrated by partial mapping of disulfide bridges within a 37-kDa protein containing 16 cysteine residues and complete disulfide mapping within a lysozyme (14.5 kDa) containing 8 cysteine residues. In addition to detecting peptide pairs connected by a single external disulfide, the new method is also shown to be capable of identifying peptides containing both external and internal disulfide bonds. The two major factors determining the efficiency of disulfide mapping using the new methodology are the effectiveness of proteolysis and the ability of the resulting proteolytic fragments to form multiply charged negative ions.

RsrA, a redox-sensing Zn-containing anti-sigma factor (ZAS) protein obtained from Streptomyces coelicolor is observed to respond to the disulfide stress, whereas it undergoes reversible and intramolceular disulfide bond formation during oxidative stress. The analysis of the assignment of the zinc ligands in RsrA shows that zinc plays a very important role in the modulation of the redox activity of the protein thiols.

The synthesis of the phosphine sulfide derivative of 1-[P.sub.i][Pr.sub.2-]indene, the use of this ligand in the preparation of neutral [[k.sup.2]-C,S] and cationic [[k.sup.2-H,S] Rh and Ir coordination complexes and the application of these complexes as catalysts for the addition of triethylsilane to styrene are reported. The observations reveal that species as well as monoanionic derivatives differ considerably in their coordination chemistry.

A new flavin catalyst immobilized in an ionic liquid ([ BMIM]PF6) is used for the highly selective oxidation of sulfides to sulfoxides by hydrogen peroxide is described. The sulfoxides are obtained in good to high yields and high selectivity without any detectable overoxidation to sulfone.

An improved methodology to remove black crusts from stone by using Desulfovibrio vulgaris subsp. vulgaris ATCC 29579, a sulfate-reducing bacterium, is described. Carbogel has proved to be superior to both sepiolite and Hydrobiogel-97, as it has allowed an easy application of the bacteria and allowed easy removal of the cells after the treatment.

Preparation of shape-controlled metastable gama-MnS semiconductor nanocrystals was achieved on a large scale through a simple solvothermal method in the presence of PVP. The optical absorption measurement reveals that these novel architectures exhibit remarkable shift of absorption peak during the course of structural compaction and grain growth.

Synthesis and characterization of three aluminum-containing tin(IV) heterobimetallic sulfides are reported. The reaction of [LAI(SLi)2(THF)2]2 [L = HC(CMeNAr)2 Ar = 2,6-[Pr2C6H3] with Ph2SnCl2, MeSnCI4 in THF respectively affords LAI(mu-S)2SnPh2, LAI(mu-S)2SnMe2, and LAI(mu-S)2Sn(mu-S)2AIL in moderate yields.

The influence of a biological target on the composition of the reaction mixture is demonstrated. Use of high-resolution ESI mass spectrometry to evaluate the composition of the mixture shows promise for the design of new large libraries.

An investigation was conducted on ruthenium-catalyzed (2+2) cycloadditions of bicyclic alkenes with alkynyl sulfides and alkynyl sulfones. The sulfide and sulfone moieties were found to be compatible with the Ru-catalyzed cycloadditions, giving the corresponding cyclobutene cycloadducts in good yields.

The arsenate-reducing, sulfide-oxidizing population of Mono Lake, California was characterized by analyzing the distribution and diversity of rrnA, cbbL, and dissimilatory arsenated reductase (arrA) genes in environmental DNA, arsenate-plus sulfide-amended lake water, mixed cultures, and isolates. The findings showed that sulfide oxidation coupled with arsenate reduction appears to proceed through a two-electron transfer, resulting in the production of arsenite and an intermediate S compound that is subsequently disproportionated.

The fluorescence correlation spectroscopy (FCS) is used to study the rotational and translational diffusion of CdSe/CdS/ZnS nanorods (NRs) of three different aspect ratios, which are coated with phytochelatin-related peptides. The results show that the diffusion constant, D(sub rot) is a very significant tool for monitoring binding and hence monitoring the diffusion of NRs using FCS can be very useful in observing binding and confirming dynamics in biological systems.

The conformationally induced electrostatic stabilization (CIES) sulfide photooxygenation mechanism was computationally examined using an ab initio model and extended to the study of new donor atoms. The MP2/6-31G(d) geometries and a natural population analysis of natural lone-pair orbitals on the donor atoms support the mechanism and reveal that oxygen and nitrogen donor groups are more stabilizing than sulfur.

Oxidative drop solution calorimetry is being developed as a general method for sulfide thermochemistry. The samples are dropped from room temperature into molten 3[Na.sub.2]O*4Mo[O.sub.3] solvent at 975 K, with oxygen bubbling through the melt to ensure rapid and complete conversion of sulfide to dissolved sulfate. Complete dissolution of sulfides and retention of sulfur in the solvent is documented by furnace tests and visual observation, consistent determination of enthalpy of drop solution, and comparison with previous data for the heat of formation of ZnS, PbS, and CdS. Enthalpies of formation (kJ/mol) from the elements ([DELTA][H.sup.0.sub.f] are determined for sphalerite (ZnS) (-206.53 [+ or -] 4.03 kJ/mol), galena (PbS) (-98.12 [+ or -] 4.37 kJ/mol), greenockite (hexagonal CdS) (-148.79 [+ or -] 4.13 k J/tool), and hawleyite (cubic CdS) (-147.65 [+ or -] 4.28 kJ/mol). Thus, hawleyite appears to be energetically very similar to greenockite but possibly slightly metastable by about 1 kJ/mol. The results confirm that oxidative drop solution calorimetry in molten sodium molybdate is a viable method for sulfide thermochemistry. It will be most useful for sulfides with moderate heats of oxidation (e.g., the Fe-S, Co-S, and Ni-S systems), and should be applicable to ternary compounds, e.g., the Fe-Ni-S and Ni-Co-S systems, and systems showing large homogeneity ranges, as well as to other chalcogenides and pnictides. Keywords: Sulfides, oxide melt solution calorimetry, enthalpy of formation, sphalerite, galena, greenockite, hawleyite