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Tuning the electronic structureof 2D materials is a very powerful asset toward tailoring their propertiesto suit the demands of future applications in optoelectronics. Strainengineering is one of the most promising methods in this regard. Wedemonstrate that even very small out-of-plane axial compression readilymodifies the electronic structure of monolayer MoS2. Aswe show through in situ resonant and nonresonant Raman spectroscopyand photoluminescence measurements combined with theoretical calculations,the transition from direct to indirect band gap semiconductor takesplace at ∼0.5 GPa, and the transition to a semimetal occursat stress smaller than 3 GPa. [ABSTRACT FROM AUTHOR]

Althoughthe surface tension of complex mixtures determines thefate of many important natural processes, the property is notoriouslydifficult to interpret. Here we announce a new method that successfullypredicts the surface tension of two synthetic and one biological polyelectrolyte/surfactantmixtures in the phase-separation region after dynamic changes in thebulk phase behavior have reached completion. The approach is basedon the nonequilibrium framework of a lack of colloidal stability ofbulk complexes in compositions around the charge match point of theoppositely charged components and requires as input parameters onlythe surface tension isotherm of the pure surfactant and some bulkmeasurements of the mixtures; no surface measurements of the mixturesare required. The complexity of the problem is reduced to a singleempirical equation. This simplification in our understanding of thesurface properties of strongly interacting mixtures involving macromoleculescan lead to the optimization of applications involving synthetic polymersand biomacromolecules such as DNA at surfaces. [ABSTRACT FROM AUTHOR]

The rearrangement of aldoximes to primary amides hasbeen studiedusing the readily available arene-ruthenium(II) complex [RuCl2(η6-C6Me6){P(NMe2)3}] (5 mol %) as catalyst. Reactions proceededcleanly in pure water at 100 °C without the assistance of anycocatalyst, affording the desired amides in high yields (70–90%)after short reaction times (1–7 h). The process was operativewith both aromatic, heteroaromatic, α,β-unsaturated, andaliphatic aldoximes and tolerated several functional groups. Reactionprofiles and experiments using 18O-labeled water indicatethat two different mechanisms are implicated in these transformations.In both of them, nitrile intermediates are initially formed by dehydrationof the aldoximes. These intermediates are then hydrated to the correspondingamides by the action of a second molecule of aldoxime or water. Akinetic analysis of the rearrangement of benzaldoxime to benzamideis also discussed. [ABSTRACT FROM AUTHOR]

The individual steps of a model Pd-catalyzed Negishicoupling betweenvinyl bromide and MeZnClS2(S = THF), using Pd(PMe3)2as catalyst, have been examined with the aidof DFT computations in THF solution with the B97D functional to gainfurther insight into the role of Pd–Zn interactions on theoxidative addition and reductive elimination steps. Comparisons betweensuch processes taking place on monometallic Pd complexes and on bimetallicPd–Zn complexes reveal a detrimental effect of Pd–Zninteractions in oxidative addition, whereas reductive eliminationis favored by Pd–Zn cooperativity. Additionally, a cis transmetalationpathway has been characterized that complements previous studies involvingtrans complexes. [ABSTRACT FROM AUTHOR]

The synthesis of various silybin monogalloyl esters was developed, and their antiangiogenic activities were evaluated in a variety of in vitro tests with human umbilical vein endothelial cells (HUVECs). A structure–activity relationship (SAR) study found the regioselectivity of the silybin galloylation to be highly significant. Silybin (as an equimolar mixture of two diastereomers A and B) exhibited quite poor antiangiogenic activities, whereas its B stereoisomer is more active than silybin A. The galloylation of phenolic OH groups of natural silybin (a mixture of both isomers) leads to increases in their antiangiogenic activities, which is more apparent with the 7-OH than the 20-OH. In contrast, gallates at aliphatic OH groups either had a comparable activity to the parent compound or are even worse than silybin, which was observed in the case of 3-O-galloylsilybin. The most effective compound from this series (7-O-galloylsilybin) has also been prepared from stereochemically pure silybins A and B to evaluate the effect of stereochemistry on the activity. As with silybin itself, the B isomer of 7-O-galloylsilybin was more active than the A isomer. [ABSTRACT FROM AUTHOR]

Inthis work experimental vapor–liquid equilibrium (VLE)data and three-phase vapor–liquid–liquid equilibrium(VLLE) data are presented for the carbon dioxide 1-decanol system.The VLE data were measured at five temperatures, (303.2, 308.2, 323.2,333.2, and 343.2) K, and pressures up to 16 MPa. The VLLE data coverpressure–temperature (P–T) values from289 K and 5 MPa to the upper critical end point (UCEP). We have usedtwo models to represent the complex fluid phase behavior (P–Tcritical curve, VLLE line, and VLE isotherms)of the carbon dioxide 1-decanol system: the cubic general equationof state (GEOS) and Peng–Robinson (PR) equation in conjunctionwith van der Waals two parameters conventional mixing rules (2PCMR).A correlation method involving temperature-dependent interaction parametersand a semipredictive approach with independent temperature interactionparameters have been used. Comparisons with experimental data reportedin this work and available in the literature indicate that the topologyof fluid phase behavior is satisfactorily given by the semipredictiveprocedure both for the critical line and in subcritical region, consideringthe relative simple used cubic equations of state. [ABSTRACT FROM AUTHOR]

Enzymaticalcoholysis of fish oil can produce monoacylglycerolsrich in polyunsaturated fatty acids at atmospheric pressure and lowtemperature. Biocatalysis in organic solvents helps to create a homogeneousreaction system for the reactants, ethanol and fish oil. This workpresents liquid–liquid equilibrium at two different temperatures(303.2 K and 323.2 K) and at atmospheric pressure for two solvent-systemsin the ethanolysis of fish oil: ethanol oil tert-pentanol and ethanol oil hexane. Experimental solubility (binodal)curves were obtained by the cloud point method and tie-line compositionwas obtained by density and high-temperature gas chromatography. Theconsistency of experimental tie-line data was checked by using theOthmer–Tobias equation. The experimental liquid–liquiddata were correlated satisfactorily by the nonrandom two liquid modelfor activity coefficient calculations. [ABSTRACT FROM AUTHOR]

A versatile,photochemical surface-modification approach usingnitrene-insertion reactions has been employed to develop an ultrathin,two-component, polymer-gradient coating. Perfluorophenyl azide (PFPA)acted as the photosensitive moiety, forming a nitrene radical upon254 nm UV exposure. Cationic poly(allyl amine) was grafted with PFPAand surface-anchored onto silicon wafers by means of electrostaticself-assembly. After spin-coating of polystyrene (PS), the substratewas illuminated from behind a moving shutter, thereby controllingthe azide-to-nitrene conversion degree across the substrate, and leadingto a gradually varying PS density after rinsing. Backfilling withpoly(vinyl pyrrolidone) (PVP) and re-exposing to UV light formed atwo-component polymer-density gradient. The composition varied linearlyfollowing exposure to a linear UV exposure profile, as determinedwith spectroscopic ellipsometry (ELM) and X-ray photoelectron spectroscopy(XPS). High-spatial-resolution, time-of-flight secondary ion massspectrometry (ToF-SIMS) revealed a high degree of mixing between thetwo incompatible polymers on the micrometer scale. The dynamic water-contactangle (dCA) was found to depend strongly on the sample history, suggestingadaptive properties of the coating, which was further confirmed byangle-resolved XPS (ARXPS). To confirm the applicability of the systemfor biological investigations, gradients were exposed to zoosporesof the macrofouling alga Ulva linza, and a critical PS composition of 70% was identified, above whichsettlement started to increase. It has been shown that a two-componentpolymer-density gradient can provide a high-throughput platform fordetermining critical surface properties of polymer blend materials. [ABSTRACT FROM AUTHOR]

Fourflavonols, namely quercetin, morin, kaempferol, and myricetin,were studied using spectrophotometry (UV–vis) in aqueous solution.The study was performed varying the pH to analyze the stability ofthese compounds, and to estimate their acidity constants. In addition,the deprotonation mechanisms were studied using computational chemistrywithin the density functional theory framework. The calculations wereperformed in aqueous solution using the SMD continuum model, and theresults are reported as deprotonation energies. Our results show thatboth quercetin and myricetin are highly unstable at basic pH. Kaempferol,on the other hand, is much more stable, and morin is the only oneamong the studied compounds that was not affected by pH. In spiteof this inconvenience, their acidity constants were estimated throughanalysis of their decomposition kinetics, correcting the spectra accordingly,and obtaining a correlation of values between the experimentally observedpKaand the calculated ΔGof successive deprotonations. [ABSTRACT FROM AUTHOR]

Itis known that conical intersections (CIs) can be induced bylaser light even in diatomics. In the close vicinity of these laser-inducedCIs (LICIs) the nonadiabatic effects are infinitely strong, as isthe case for naturally appearing CIs in field-free polyatomics. Inthe present work we study the photodissociation dynamics of the D2骉干 inan intense laser field to investigate the role of the LICI. Specifically,the kinetic energy release (KER) and the angular distribution of thephotodissociation products are calculated with and without LICI fordifferent initial conditions and for different values of the laserparameters. To do so, both one- and two-dimensional calculations wereperformed. In the first model the molecules were rotationally frozen,whereas in the latter one, the molecular rotation is included as afull additional dynamic variable. The results obtained undoubtedlydemonstrate the strong impact of the coupling of the rotation to thevibrational and electronic motions and hence of the LICI on the dissociationdynamics of the D2骉干. [ABSTRACT FROM AUTHOR]

The polarity of the ionic liquids [N4111][Tf2N], [N4441][Tf2N], and [choline][Tf2N], as well as their binary mixtures with ethanol has beeninvestigatedusing solvatochromic dyes and expressed in terms of the Reichardtparameter, ETN, and the Kamlet–Taft parameters (π*,α, and β), at 298.15 K. The synergetic behavior revealedessentially by the ethanol [N4441][Tf2N] systemfor the acidity of the solvent shows the potential importance of thissolvent media for some chemical applications. Even though the preferentialsolvation model of Bosch and co-workers has been applied with somestatistical success to the whole composition range of EtOH [N4111][Tf2N] and EtOH [N4441][Tf2N] binary mixtures, the interpretation of the results is somehowdifficult due to the competition of molecular interactions in theevaluation of transition energies for the pairs: dye–solvent(dye–cation and/or dye–anion, dye–EtOH, dye–complexentity) and cation–anion, depending on the composition range.Different patterns of solvent polarity behavior are shown along theentire ionic liquid (IL) composition. [ABSTRACT FROM AUTHOR]

One of the most significant recent developments (in 2009)is the discovery of the clusters M@Ge103–(M = Fe, Co) in which the outer Ge10polyhedron is apentagonal prism rather than a deltahedral structure of the type predictedby the Wade–Mingos rules. Consistent with this experimentalobservation, density functional theory shows the lowest energy structuresto be pentagonal prisms for the iron-centered clusters Fe@Ge10zin all nine charge states ranging from−5 to . This contrasts with the previously studied cobalt-centeredgermanium clusters Co@Ge10zfor which the lowest energy structures are pentagonal prisms onlyfor the electron richest systems where zranges from−3 to −5. The C3vstructures derived from the tetracapped trigonal prism foundas lowest energy structures of the electron poorer Co@Ge10z(z= 0, −1,−2) systems are higher energy structures for the iron-centeredgermanium clusters Fe@Ge10z(z= 0, −1, −2). The strong energeticpreference for pentagonal prismatic structures in the Fe@Ge10zclusters can be attributed to the needfor the larger volume of the pentagonal prism relative to other 10-vertexclosed polyhedra to accommodate the interstitial iron atom. [ABSTRACT FROM AUTHOR]

Transesterification of triolein in excess methanol oversodium-loadedcatalysts prepared from Na-ion exchange with zeolites at a relativelylower reaction temperature, namely, at 60 °C, is studied in thiswork. Two zeolites, i.e., as-synthesized ZeoliteMCM-22 and commercial Zeolite HY (CBV-780), are employed in this study.Althoughboth zeolites show to some extent the capability of catalyzing transesterificationof triolein in methanol to biodiesel, the resulting yields are onlyca. 90% for CBV-780 after a 40-h reaction and 16.3% for MCM-22 aftera90-h reaction. In contrast, the conversion yields are much improvedwith Na-ion exchange to the surface of zeolite catalysts. For example,the yields of triolein to biodiesel have reached 98% and 99% withina 5.5-h reaction, respectively, using the NaOH-treated CBV-780 andMCM-22 catalysts, even if these NaOH-treated catalysts become amorphousand have suffered a loss of the Brunauer–Emmett–Tellersurface area. Furthermore, no saponification was observed using theseNaOH-treated catalysts. [ABSTRACT FROM AUTHOR]

Previous studies have shown that hybrid fermentation–pervaporationsystems can be attractive for ethanol production. Simultaneous removalof the ethanol produced promises to improve yield and to reduce operationtime and the energy required for ethanol purification. This paperexperimentally explores the effect of pH (3–5.7), CO2(at saturated conditions), and high glucose concentrations (50–400g/L) on the flux and selectivity of PDMS (polydimethylsiloxane) pervaporationmembranes at several ethanol concentrations (50–100 g/L) andtemperatures (278–313 K). Membrane performance has been simulatedusing a Henry solution model combined with a Maxwell–Stefandescription of mass transport through the membrane. By adjusting themodel to the water–ethanol experimental data, it was possibleto calculate the relative solubility and diffusion between ethanoland water in the polymeric membrane. Experimental results showed thatthe higher the glucose concentration is, the higher the membrane selectivityto ethanol will be due to a reduction on water flux. However, at aglucose concentration of 400 g/L a strong drop of total flux was measured.CO2permeates through the PDMS membrane, but it does nothave any effect on ethanol or water flux and, consequently, on selectivity.On the contrary, as pH is reduced so does selectivity while the totalflux increases. Low pH values produce a decrease in membrane hydrophobicity,increasing water transport. The results presented in this paper contributeto the design of hybrid fermentation and pervaporation units, especiallythose that can operate at high glucose concentrations. [ABSTRACT FROM AUTHOR]

Full dimensional quantum dynamics calculations of thethree lowestisomers of the He4Br2van der Waals moleculein its ground electronic state are reported. The calculations areperformed using the multiconfiguration time-dependent Hartree (MCTDH)method and a realistic potential form that includes the sum of threebody ab initio coupled-cluster single double triple [CCSD(T)] He–Br2interactions plus the He–He and Br–Br interactions.This potential exhibits several multiple minima, with the three lowestones lying very close in energy, just within 2 cm–1. Such small differences are also found in the calculated bindingenergies of the three most stable conformers, indicating the floppinessof the system and, thus, the need of accurate potential forms andquantum full dynamics methods to treat this kind of complexes. The12 dimensional results reported in this work present benchmark dataand, thus, can serve to evaluate approximate methods aiming to describehigher order rare gas–dihalogen (N> 4)complexes.A comparison with previous studies using different potential formsand approaches to the energetics for the He4Br2cluster is also presented. [ABSTRACT FROM AUTHOR]

The friction and adhesion between pairs of materials(silica, alumina,and polytetrafluoroethylene) have been studied and interpreted interms of the long-ranged interactions present. In ambient laboratoryair, the interactions are dominated by van der Waals attraction andstrong adhesion leading to significant frictional forces. In the presenceof the ionic liquid (IL) ethylammonium nitrate (EAN) the van der Waalsinteraction is suppressed and the attractive/adhesive interactionswhich lead to “stiction” are removed, resulting in anat least a 10-fold reduction in the friction force at large appliedloads. The friction coefficient for each system was determined; coefficientsobtained in air were significantly larger than those obtained in thepresence of EAN (which ranged between 0.1 and 0.25), and variationin the friction coefficients between systems was correlated with changesin surface roughness. As the viscosity of ILs can be relatively high,which has implications for the lubricating properties, the hydrodynamicforces between the surfaces have therefore also been studied. Thelinear increase in repulsive force with speed, expected from hydrodynamicinteractions, is clearly observed, and these forces further inhibitthe potential for stiction. Remarkably, the viscosity extracted fromthe data is dramatically reduced compared to the bulk value, indicativeof a surface ordering effect which significantly reduces viscous losses. [ABSTRACT FROM AUTHOR]

An in-depth study of the ion transfer facilitated bycomplexationin the organic phase (TOC mechanism) in liquid membrane systems ofone and two polarized interfaces is carried out by taking into accountthe kinetic effects associated with the complexation reaction. Explicitanalytical equations for the normal pulse voltammetric (I/E) and chronoamperometric (I/t) responses with an explicit dependence on the kineticparameters of the chemical complexation are presented for both kindsof membrane system, which could be useful for modeling artificialand biological membranes. The equations are compared with those obtainedby using the widely used approximation of total equilibrium conditionsthat leads to the transfer by interfacial complexation mechanism (TIC),which only depends on thermodynamic parameters. Simple methods areproposed that allow quantitative determination of the equilibriumand kinetic constants of the complexation reaction in the organicphase for both kinds of membrane system. [ABSTRACT FROM AUTHOR]

In this article, we report the findings of a comprehensivestructure–activityrelationship study of N-(6-ferrocenyl-2-naphthoyl)dipeptide ethyl esters, in which novel analogues were designed, synthesized,and evaluated in vitrofor antiproliferative effect.Two new compounds, 2and 16, showed potentnanomolar activity in the H1299 NSCLC cell line, with exceptionalIC50values of 0.13 and 0.14 μM, respectively. Thesecompounds were also found to have significant activity in the Sk-Mel-28malignant melanoma cell line (IC50values of 1.10 and 1.06μM, respectively). Studies were also conducted to elucidatethe mode of action of these novel organometallic anticancer compounds.Cell cycle analysis in the H1299 cell line suggests these compoundsinduce apoptosis, while guanine oxidation studies confirm that 2is capable of generating oxidative damage via a ROS-mediatedmechanism. [ABSTRACT FROM AUTHOR]

In this study, kinetics of formic acid-catalyzed xylosedehydrationinto furfural and furfural decomposition was investigated using batchexperiments within a temperature range of 130–200 °C.Initial xylose and furfural concentrations up to 0.2 and 0.08 mol/L,respectively, were used. The room temperature pH of the formic acidcatalyst solution was between 0.9 and 1.7. The kinetic model usedwas based on a specific acid catalysis model and included the prevailinghydrogen ion concentration in reaction conditions. The study showedthat the modeling must account for other reactions for xylose besidesdehydration into furfural. Moreover, the reactions between xyloseintermediate and furfural play only a minor role. The study also showedthat kinetic modeling of xylose and furfural decomposition reactionsmust take the uncatalyzed reaction in water solvent into account. [ABSTRACT FROM AUTHOR]

Thin and narrow conductive patterns of metal (silver)and organicpolymer (polyaniline) were printed on various coated paper samples.A detailed characterization of the physical properties (i.e., shortlength scale roughness, surface energy, and air permeability) of thepaper samples was conducted. These properties were correlated withprint quality (print resolution and edge waviness) and electricalperformance (resistance) of the printed wires. A plastic film wasused as a reference substrate. The print resolution and the magnitudeof the edge waviness were affected by the complex interplay of differentphysical properties of both the substrate and the ink. On the otherhand, the resistance of the printed wires was found to correlate linearlywith the short length scale roughness of the print substrate. Theelectrical performance of the paper substrates showing the highestconductivity for the printed patterns was comparable to that of theplastic film. The paper substrate on which the printed wires showedthe best electrical performance was used as a substrate for fabricationof an organic transistor with low operating voltage. [ABSTRACT FROM AUTHOR]

In this article, we investigate experimentally a widerange ofsituations where charge inversion (i.e., overcompensation of the surfacecharge of a colloidal particle by the countercharge) can occur. Tothat end, the electrophoretic mobility of sodium montmorillonite,silica, and polystyrene latex as functions of pH and concentrationof different salts is presented, and conditions are established wherecharge inversion occurs. The reason for this study is to provide experimentalevidence for distinguishing between two existing models for the explanationof charge inversion. One of these is the specific adsorption of ionslocated in the Stern layer in combination with a Gouy–Chapmandiffuse part of the double layer. The other ion-correlation theoriesexplain the phenomenon in terms of purely physical arguments basedon Coulombic pair interactions between ions and surface charges andon excluded volume effects. In distinguishing between these two interpretations,the influence of the pH plays a central role because of its effecton the hydrolysis of multivalent cations. In our experiments, it isfound that although 1–2 and 2–2 electrolytes provokea decrease in the absolute values of the electrophoretic mobilitieswhen their concentration in solution is increased, they never leadto charge inversion, whatever the surface charge or the pH. However,in the case of salts of trivalent cations, electrokinetic charge reversalis often observed above a certain critical electrolyte concentration.In addition, the extent of overcharging increases when the concentrationis raised above the critical value. This trend occurs for any systemin which the surface charge is pH-independent, as in polystyrene latexand montmorillonite. Most of the results presented here are compatiblewith the specific adsorption of hydrolyzed metal ions as the maindriving force for charge inversion. At low pH, when the hydrolysisof trivalent cations is likely to be absent, overcharging can be attributedto ion correlation effects. [ABSTRACT FROM AUTHOR]

The recrystallization of caffeine extracted with dichloromethanefrom coffee beans by a supercritical antisolvent (SAS) process wasstudied. Acicular crystalline particles with a particle size downto 2.5 μm were obtained, and product purity was increased asa result of SAS processing. Furthermore, by modification of processconditions, it was possible to vary the proportion between the metastableand stable crystalline polymorphic forms of caffeine, obtaining fractionsof stable form ranging from 40% to nearly 100%. [ABSTRACT FROM AUTHOR]

A computational study of the reaction of P(3P) with acetylene has been carried out. The only exothermicproducts correlating with the reactants are PCCH(2Π) H(2S). Two different pathways leadingto these products that are apparently barrier-free have been found.Both pathways involve isomerization into open-chain intermediatesfollowed by direct elimination of a hydrogen atom. The possibilityof spin-crossing has been considered because the species on the singletsurface are considerably more stable than those on the triplet one.On the singlet surface, there are other possible channels for thereaction, namely, cyclic PC2H(2A′) H(2S) and CCP(1Σ) H2(1Σg). A computationalkinetic study shows that, in agreement with the experimental evidence,the major products are PCCH(2Π) H(2S) at all temperatures. Only at very high temperatures isCCP(1Σ) H2(1Σg) formed in non-negligible amounts.Therefore, only PCCH눚⺕ be formed in the interstellarmedium. [ABSTRACT FROM AUTHOR]

The relaxation dynamics of the isolated indole molecule has been tracked by femtosecond time-resolved ionization. The excitation region explored (283–243 nm) covers three excited states: the two ππ* Lband Lastates, and the dark πσ* state with dissociative character. In the low energy region (λ > 273 nm) the transients collected reflect the absorption of the long living Lbstate. The Lastate is met 1000–1500 cm–1above the Lborigin, giving rise to an ultrafast lifetime of 40 fs caused by the internal conversion to the lower Lbminimum through a conical intersection. An additional ∼400 fs component, found at excitation wavelengths shorter than 263 nm, is ascribed to dynamics along the πσ* state, which is likely populated through coupling to the photoexcited Lastate. The study provides a general view of the indole photophysics, which is driven by the interplay between these three excited surfaces and the ground state. [ABSTRACT FROM AUTHOR]

We present a detailed study for the short-time dynamics through conical intersections in molecular systems related to the quadratic vibronic coupling (QVC) Hamiltonian [Müller, H.; Köppel, H.; Cederbaum, L. S. NewJ. Chem. 1993, 17, 7–29] and the effective-mode formalism [Cederbaum, L. S.; Gindensperger, E.; Burghardt, I. Phys. Rev. Lett. 2005, 94, 113003]. Our approach is based on splitting the nuclear degrees of freedom of the whole system into system modes and environment modes. It was found that only three-effective environmental modes together with the system’s modes are needed to describe the short-time dynamics of the complex system correctly. In addition, a detailed mathematical proof is given in the appendix to demonstrate that the exact cumulants are recovered up to the second order within the cumulant expansion of the autocorrelation function. The butatriene molecule is studied as an explicit showcase example to stress the viability of our proposed scheme and to compare with other systems. [ABSTRACT FROM AUTHOR]

The E 3Πgstate of the iodinemolecule is studied by ab initio multireference methods coupled witheffective core potentials and large basis sets. Two potential minimaare found, a global featuring an ion-pair character, and a local presentinga purely Rydberg nature. Four avoided crossings along the dissociationcoordinate attribute an interesting topology to its potential energycurve, and their effect on the vibrational levels of I2is discussed. [ABSTRACT FROM AUTHOR]

The paper reports the isothermal vapor–liquidequilibria(VLE) of five binary mixtures containing 2-butanol heptane, 2,2,4-trimethylpentane, dodecane, cyclohexane, and methylbenzene at 313.15 K. A statictechnique has been used for the measurements. Data reduction by Barker'smethod provides the parameters of GEmodels.The six-parameter Margules equation, Wilson, nonrandom two-liquid(NRTL), and universal quasichemical activity coefficient (UNIQUAC)models have been used for the correlation of the experimental data.Good results have been obtained for all. The five investigated mixturesexhibit a positive deviation from ideality, and four of them showa maximum pressure azeotrope. Only the mixture 2-butanol dodecanedoes not present an azeotrope. [ABSTRACT FROM AUTHOR]

Liquid–liquid equilibrium (LLE) data are presentedfor ammoniumbased ionic liquids (ILs) dibenzothiophene (DBT) n-dodecane at 298.2 K and atmospheric pressure (∼95 kPa). Molefractions were determined by the refractometry or graphical method.DBT phase distribution, ionic liquid selectivity, and DBT percentextraction were determined. Ionic liquids used here were comparedwith imidazolium in terms of sulfur removal. Hand and Othmer–Tobiascorrelations were used to test the LLE data and gave σ <0.09 (R2> 0.90). The nonrandom two-liquidmodel (NRTL) was used to correlate the LLE data, giving percent root-mean-squaredeviations < 0.22 between experimental and calculated mole fractions. [ABSTRACT FROM AUTHOR]

The spectroscopy and kinetics of the tyrosinase catalyzed trans-resveratrol oxidation were investigated by measuringboth UV–vis absorption spectra over the 200–500 nm rangeand Raman spectra over the 600–1800 cm–1region.Room temperature UV–vis absorption spectra, as a function oftime, showed the presence of two isosbestic points located at λ1= 270 nm and λ2= 345.5 nm delimiting twodifferent regions: the reactant region around 300 nm, where the absorptiondecreased with time, and the product region over the low wavelength(λ < 260 nm) and high wavelength (λ > 390 nm) wavelengthzone in which the absorption increased with time until, in both cases,constant values were achieved. A first-order kinetics was deducedwith a rate coefficient of k1= (0.10± 0.001) min–1, which turned out to be independentof substrate concentration over the 50–5 μM range; afeature that was rationalized by invoking the limiting case of theMichaelis–Menten scheme appropriate for substrate concentrationmuch lower than the respective Michaelis constant. The observationof the distinct resonance enhanced Raman lines, specifically thosepeaking at 830 cm–1, 753 cm–1,and 642 cm–1together with their time evolution,permitted us to gain insight into some crucial features and stepsof the catalytic reaction. Namely, that the formation of the so-called trans-resveratrol and tyrosinase SP complex withits O–O bridge plays a crucial role in the first steps of thisenzymatic reaction and that the hydroxylation of the ortho C–Hbond of the trans-resveratrol OH group occurs afterO–O bond cleavage in the tyrosinase activesite. The present study makes clear that a class of potential inhibitorsof tyrosinase can be found in compounds able to bind the two Cu (II)ions of the enzyme bidentate form. [ABSTRACT FROM AUTHOR]