ORBi Collection: Chemistry
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Nonalkaline solubilization of arabinoxylans from destarched wheat bran using hydrothermal microwave processing and comparison with the hydrolysis by an endoxylanase
http://hdl.handle.net/2268/185448
Title: Nonalkaline solubilization of arabinoxylans from destarched wheat bran using hydrothermal microwave processing and comparison with the hydrolysis by an endoxylanase
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<br/>Author, coauthor: Aguedo, Mario; Ruiz, Héctor A.; Richel, Aurore

Exitchannel dynamics in barrierless unimolecular reactions: Criteria of vibrational adiabaticity
http://hdl.handle.net/2268/185438
Title: Exitchannel dynamics in barrierless unimolecular reactions: Criteria of vibrational adiabaticity
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<br/>Author, coauthor: PavlovVerevkin, Victor B.; Lorquet, JeanClaude
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<br/>Abstract: Conversion of translational into vibrational energy during the last step of a unimolecular reaction is brought about by the curvature of the reaction path. The corresponding coupling is analyzed by an angleaction reaction path Hamiltonian (RPH). The accuracy of the vibrational adiabatic approximation is found to be completely independent of the shape of the potential energy V(s). Vibrations are adiabatic when two independent dimensionless parameters are small. The first one, denoted as sigma, controls the dynamic coupling. The physical significance of the condition sigma << 1 is that the amplitude of the vibrations normal to the reaction path should be much smaller than the radius of curvature of the reaction path. The second parameter, denoted as mu, governs the static coupling. It results from the dependence of the vibrational frequency omega on the reaction coordinate s. The higher omega, the lower its derivative with respect to s and, more unexpectedly, the higher the translational energy epsilon, the lower mu is. A criterion for locating a particular dividing surface in barrierless reactions is proposed. This surface separates two regions of space: one where energy flows freely, and one where energy conversion between translation and vibration is hindered by adiabatic invariance. The nature of the dynamical constraint that prevents the product translational energy distribution from being fully statistical can be identified by a maximum entropy analysis. The constraint is found to bear on the translational momentum p(s), i.e., on the square root of the translational energy epsilon(1/2). This can be understood by applying Jacobi's form of the least action principle to the vibrationally adiabatic RPH. (c) 2005 American Institute of Physics.

Crossing the dividing surface of transition state theory. II. Recrossing times for the atomdiatom interaction
http://hdl.handle.net/2268/185436
Title: Crossing the dividing surface of transition state theory. II. Recrossing times for the atomdiatom interaction
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<br/>Author, coauthor: Lorquet, JeanClaude
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<br/>Abstract: We consider a triatomic system with zero total angular momentum and demonstrate that, no matter how complicated the anharmonic part of the potential energy function, classical dynamics in the vicinity of a saddle point is constrained by symmetry properties. At short times and at not too high energies, recrossing dynamics is largely determined by elementary local structural parameters and thus can be described in configuration space only. Conditions for recrossing are given in the form of inequalities involving structural parameters only. Explicit expressions for recrossing times, valid for microcanonical ensembles, are shown to obey interesting regularities. In a forward reaction, when the transition state is nonlinear and tight enough, onefourth of the trajectories are expected to recross the plane R = R o (where Ro denotes the position of the saddle point) within a short time. Another fourth of them are expected to have previously recrossed at a short negative time, i.e., close to the saddle point. These trajectories do not contribute to the reaction rate. The reactive trajectories that obey the transition state model are to be found in the remaining half. However, no conclusion can be derived for them, except that if recrossings occur, then they must either take place in the distant future or already have taken place in the remote past, i.e., far away from the saddle point. Trajectories that all cross the plane R = Ro at time t = 0, with the same positive translational momentum P can be partitioned into two sets, distinguished by the parity of their initial conditions; both sets have the same average equation of motion up to and including terms cubic in time. Coordination is excellent in the vicinity of the saddle point but fades out at long (positive or negative) times, i.e., far away from the transition state. © 2014 AIP Publishing LLC.

Crossing the dividing surface of transition state theory. I. Underlying symmetries and motion coordination in multidimensional systems
http://hdl.handle.net/2268/185434
Title: Crossing the dividing surface of transition state theory. I. Underlying symmetries and motion coordination in multidimensional systems
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<br/>Author, coauthor: Lorquet, JeanClaude
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<br/>Abstract: The objective of the present paper is to show the existence of motion coordination among a bundle of trajectories crossing a saddle point region in the forward direction. For zero total angular momentum, no matter how complicated the anharmonic part of the potential energy function, classical dynamics in the vicinity of a transition state is constrained by symmetry properties. Trajectories that all cross the plane R = Ro at time t = 0 (where Ro denotes the position of the saddle point) with the same positive translational momentum PRo can be partitioned into two sets, denoted "gerade" and "ungerade," which coordinate their motions. Both sets have very close average equations of motion. This coordination improves tremendously rapidly as the number of degrees of freedom increases. This property can be traced back to the existence of timedependent constants of the motion. © 2014 AIP Publishing LLC.

Erratum: Crossing the dividing surface of transition state theory. I. Underlying symmetries and motion coordination in multidimensional systems (J. Chem. Phys. 140 (2014) (134303))
http://hdl.handle.net/2268/185433
Title: Erratum: Crossing the dividing surface of transition state theory. I. Underlying symmetries and motion coordination in multidimensional systems (J. Chem. Phys. 140 (2014) (134303))
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<br/>Author, coauthor: Lorquet, JeanClaude
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<br/>Abstract: [No abstract available]

Characterization Of Astrocaryum Macrocalyx Kernel Fat.
http://hdl.handle.net/2268/185400
Title: Characterization Of Astrocaryum Macrocalyx Kernel Fat.
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<br/>Author, coauthor: Lognay, Georges; Desmedt, A.; Mejia, K.; Trevejo, E.; Marlier, M.

Li4Ti5O12 powders by spraydrying: influence of the solution concentration and particle size on the electrochemical properties
http://hdl.handle.net/2268/185399
Title: Li4Ti5O12 powders by spraydrying: influence of the solution concentration and particle size on the electrochemical properties
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<br/>Author, coauthor: Jamin, Claire; Brisbois, Magali; Caes, Sébastien; Krins, Natacha; Cloots, Rudi; Vertruyen, Bénédicte; Boschini, Frédéric

Chemical Characterization Of TylosemaFassoglensis (Kotschy) Torre And Hillc Oilseed
http://hdl.handle.net/2268/185396
Title: Chemical Characterization Of TylosemaFassoglensis (Kotschy) Torre And Hillc Oilseed
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<br/>Author, coauthor: Dubois, Michel; Lognay, Georges; Baudart, E.; Marlier, M.; Severin, M.; Dardenne, G.; Malaisse, F.
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<br/>Abstract: Tylosema fassoglensis seeds contain high levels of lipids (240–300 g kg−1) and proteins (446 g kg−1 dry weight). Major fatty acids contained in the oil are linoleic (36–42% of the total fatty acids) oleic (32–35%) and palmitic (11.5–15.7%) acids. The proteins are characteristic with their high levels of lysine, proline and tyrosine. Due to their very low content, both methionine and cystine appear to be the limiting amino acids. Tylosema fassoglensis defatted meal contains substantial amounts of trypsin inhibitors and phytates 295 TUI mg−1 and 35 g kg−1 dry weight, respectively.

Edible Fats And Oils Reference Materials For Sterol Analysis With Particular Attention To Cholesterol .2. Certification Of Sterols Mass Fraction
http://hdl.handle.net/2268/185395
Title: Edible Fats And Oils Reference Materials For Sterol Analysis With Particular Attention To Cholesterol .2. Certification Of Sterols Mass Fraction
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<br/>Author, coauthor: Lognay, Georges; Pearse, J.; Pocklington, D.; Boenke, A.; Schurer, B.; Wagstaffe, Pj.
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<br/>Abstract: The design and results of an interlaboratory exercise for the certification of the cholesterol mass fraction in three edible oils and fats reference materials within the EEC Measurements and Testing programme (formerly Community Bureau of ReferenceBCR) are described. The certified cholesterol contents are 2.5 ± 0.5, 133.6 ± 4.7 and 274.7 ± 9.0 mg of cholesterol per 100 grams for CRM 162 (soya–maize oil blend), CRM 163 (a pig and beef fat blend) and CRM 164 (anhydrous milkfat), respectively. Phytosterols (βsitosterol, stigmasterol and campesterol) added as ‘markers’ to milkfat not destined for manufacturing butter have also been certified at 52.9 ± 4.0, 20.3 ± 0.6 and 35.6 ± 1.3 mg per 100 grams of fat, respectively. Indicative values for the sterol content of CRM 162 are also presented.

Composition of the Cuticular Waxes of Picea abies and P. sitchensis
http://hdl.handle.net/2268/185393
Title: Composition of the Cuticular Waxes of Picea abies and P. sitchensis
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<br/>Author, coauthor: Prügel, B.; Lognay, Georges
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<br/>Abstract: The chemical compositions of the cuticular lipids of the needles of Norway spruce (Picea abies (L.) Karst.) and Sitka spruce (P. sitchensis) (Bong.) Carr.) were investigated by gas chromatography coupled with mass spectrometry. Fractionation of the wax extracts was carried out using column chromatography. Long chain secondary alcohols, diols and free fatty acids were found as major classes in both species: nalkanes, nalkenes, primary alcohols, a,wdiols, ketones and whydroxyacids constituted the minor wax classes. The presence of
large quantities of estolides (high molecular weight biopolymers) was tentatively confirmed by saponification of the crude extracts which led to the recovery of large quantities of whydroxyacids, a,wdiols and free fatty acids. Qualitative differences between the two examined species were observed for minor constituents such as long chain aldehydes, methyl and ethylesters and some terpenes. Quantitatively the two wax extracts differed mainly
in their proportions of diols and fatty acids.

Conducting, selfassembled, nacremimetic polymer/clay nanocomposites
http://hdl.handle.net/2268/185333
Title: Conducting, selfassembled, nacremimetic polymer/clay nanocomposites
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<br/>Author, coauthor: Mäkiniemi, Roi Oskari; Das, Paramita; Hönders, Daniel; Grygiel, Konrad; Cordella, Daniela; Detrembleur, Christophe; Yuan, Jiayin; Walther, Andreas
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<br/>Abstract: We demonstrate electrically and ionically conducting nacremimetic nanocomposites prepared using selfassembly of synthetic nanoclay in combination with PEDOT:PSS and a poly(ionic liquid) polymer from aqueous dispersions. The resulting nacremimetics show high degrees of mesoscale order and combine high stiffness and high strength. In terms of conductivities, the resulting hybrids exceed simple additive behavior and display synergetic conductivities due to high levels of interfaces and anisotropic conductivity pathways. The approach highlights the integration of relevant functionalities into stiff and strong bioinspired materials, and shows that synergetic properties beyond mechanical performance can be realized in advanced multifunctional nanocomposites using nacreinspired design principles.

Excited states of gaseous ions. Transitions to and predissociation of the C2Σ+ u state of N2+
http://hdl.handle.net/2268/185321
Title: Excited states of gaseous ions. Transitions to and predissociation of the C2Σ+ u state of N2+
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<br/>Author, coauthor: Lorquet, JeanClaude; Desouter, Michèle
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<br/>Abstract: A configuration interaction study of different electronic states of N+ 2 has been performed. The position in energy and the relative intensity of the photoelectron bands of the 2Σ+ u states has been calculated and compared with experiment. The C2Σ+ u state is predissociated by a 4Πu state, as previously supposed. However, owing to the attractive nature of the 4Πu state a double crossing occurs. Several predissociation mechanisms of the C state can therefore take place; their lifetimes have been calculated. © 1972.

Intramolecular vibrational relaxation seen as expansion in phase space. II. Reference ergodic systems
http://hdl.handle.net/2268/185320
Title: Intramolecular vibrational relaxation seen as expansion in phase space. II. Reference ergodic systems
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<br/>Author, coauthor: PavlovVerevkin, V. B.; Lorquet, JeanClaude
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<br/>Abstract: The aim of the paper is to estimate the volume of phase space that is, in principle, available to a nonstationary wave packet during its intramolecular vibrational relaxation. For that purpose, use is made of the maximum entropy method, together with the concept of constrained ergodicity to construct two socalled reference ergodic systems. The first one concerns thermal excitation processes. In that case, the only two constraints that are imposed on the intramolecular dynamics arise from the normalization of the wave function and from the conservation of. energy. These constraints affect the zeroth and first moments of the spectrum. The second reference system concerns a situation where, as an additional constraint, use is made of the information that the system has been prepared spectroscopically, i.e., by a specific .excitation process, consisting in the coherent excitation of an initial pure state. Then, the second moment of the spectrum, denoted cr, is shown to provide the appropriate additional constraint. Translated into the time domain, the prior knowledge of the dynamics used as a constraint is limited to an infinitesimally brief period of time [0,dt] with the remaining evolution determined by the maximum entropy method. The spectroscopic reference system constructed in that way can be understood as the one that samples the maximal volume of phase space available to a wave packet having a specified average energy and being put in motion by a specified initial force. Closedform expressions are obtained for the phase space volumes occupied by these two reference systems for various simple parametrizations of the function D(E) that expresses the density of states as a function of the internal energy (power laws or exponential increase). Thermal reference systems are found to sample a larger volume of phase space than their spectroscopic counterparts. The difference between these two cases depends critically on the value of σ, and also on the symmetry characteristics of the excitation process. In general, the volumes occupied by the reference systems, thermal as well as spectroscopic, can be expressed as ηE avD(E av), where E av is the (conserved) average energy of the wave packet and η is a correcting factor that depends on the functional form of D(E) and on the nature of the imposed constraints. In all cases studied, the value of η was found not to greatly differ from 1. The method has been applied to the analysis of three experimental photoelectron spectra presenting different spectral characteristics (X̃ 2A 1 state of NH 3 +, X̃ 2B 3 state of C 2H 4 +, and the X̃ 2A″ state of C 2H 3F +). The fractional occupancy index F defined by Heller as the fraction of the available phase space eventually explored up to the break time T B could be determined. After a time of the order of 100 fs, F was found to be of the order of a few percent for thermal excitation. When the molecule presents some symmetry, the expansion of the wave packet is restricted to that part of phase space spanned by the totally symmetric wave functions. The use of this additional a priori knowledge increases the fractional index F. © 1996 American Institute of Physics.

Unimolecular reaction dynamics from kinetic energy release distributions. VI. Energyselected ions
http://hdl.handle.net/2268/185319
Title: Unimolecular reaction dynamics from kinetic energy release distributions. VI. Energyselected ions
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<br/>Author, coauthor: Lorquet, JeanClaude
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<br/>Abstract: The kinetic energy distribution (KERD) determined by Brand et al. [Chem. Phys. 76 (1983) 111] for the iodine loss from energyselected iodopropane ions has been analyzed by the maximum entropy method. The entropy deficiency DS has been determined and the value of e(DS), which measures the efficiency of phasespace sampling, has been found equal to about 96%, thus corresponding to a nearly fully statistical situation. The phase space theory of Klots describes a slightly more constrained situation with e(DS) ≃ 77%. A rapid determination of the sampled fraction of phase space is possible from energyselected KERDs, based on the fact that there exists a direct relationship between the efficiency e(DS) and the reduced maximum of the KERD ε(red)/(M) = ε(M) (E)/<ε>(E). The product ε(M)(E) P(ε(M)/E) or ε(red)/(M) P(ε(red)/(M)) holds the same property. (C) 2000 Elsevier Science B.V.

Ionization potential of ammoniasome implications concerning Koopman's theorem
http://hdl.handle.net/2268/185318
Title: Ionization potential of ammoniasome implications concerning Koopman's theorem
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<br/>Author, coauthor: Lorquet, JeanClaude
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<br/>Abstract: [No abstract available]

Energytransfer phenomena and dissociation processes in electronically excited molecules
http://hdl.handle.net/2268/185317
Title: Energytransfer phenomena and dissociation processes in electronically excited molecules
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<br/>Author, coauthor: Lorquet, JeanClaude; Elkomoss, S. G.; Magee, J. L.
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<br/>Abstract: This paper is an extension of previous work by Magee and Funabashi on the influence of electronic coupling on dissociation mechanisms. The same model (linear chain of diatomic molecules) has again been considered. The use of a dynamical version of the HellmannFeynman theorem allows the development of a unified treatment valid for any coupling. An application to an infinite linear chain of hydrogen moleculeions is made, and the following results are found: (1) In the weakcoupling case, immediate dissociation occurs. (2) In the intermediate case, the electronic excitation energy is converted into vibrational energy, mainly localized on the molecule initially excited. Redistribution of the vibrational energy then occurs. (3) In the strongcoupling case, dissociation does not occur. Many molecules vibrate with comparable amplitudes. Short chains, containing two, three, four, and seven molecules, are also considered. For these it is found that two or more dissociations usually occur regardless of the type of coupling and initial position of the excitation. Finally, an application to intramolecular energy transfer is attempted. The case of the radiation induced isomerization of cispolybutadiene into its trans isomer, studied by Golub, is examined. With certain restrictions, our results can be considered as supporting Golub's views.

Excited states of gaseous ions. VI. Potential energy surfaces of CH2+
http://hdl.handle.net/2268/185316
Title: Excited states of gaseous ions. VI. Potential energy surfaces of CH2+
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<br/>Author, coauthor: Galloy, C.; Lorquet, JeanClaude
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<br/>Abstract: Several lowlying excited states of the CH2 + ion have been studied by ab initio GTOSCFCL methods. Optimized geometries and energy differences are given for seven of them: B̃2B2, ã4A2, C̃2A2, D̃2A2, 4A2(2), 2B1(2) and 4A2(3), in the order of increasing energies. Potential energy surfaces are given for the B̃2B2 and for the first three 4A2 states. These calculations enable us to discuss experimental results concerning the metastable decay (predissociation) of the CH2 + ion, as well as some of its ionmolecule reactions. © 1978.

Role Of Surface Chemical Signals In Egg Cannibalism And Intraguild Predation In Ladybirds (Coleoptera : Coccinellidae)
http://hdl.handle.net/2268/185277
Title: Role Of Surface Chemical Signals In Egg Cannibalism And Intraguild Predation In Ladybirds (Coleoptera : Coccinellidae)
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<br/>Author, coauthor: Hemptinne, Jl.; Lognay, Georges; Gauthier, Carole; Dixon, Afg.
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<br/>Abstract: The eggs of some ladybirds are known to be toxic to intraguild ladybird predators. However, this
defence is of little value if the eggs are killed before their toxicity becomes apparent. The results presented in this paper indicate that chemicals on the surface of the eggs of two species of ladybirds signal the relative risk of cannibalism and intraguild predation. In Adalia
bipunctata and Coccinella septempunctata, 87% of the chemicals are alkanes. Each species of ladybird is less reluctant to eat their own eggs than those of the other species. This asymmetry is to be expected because there is a greater risk to ladybirds from intraguild predation than cannibalism. Similar alkanes to those on the surface of the eggs of A. bipunctata are present in tracks left by larvae and on the elytra of the adults of this species. Those in the larval tracks deter females from ovipositing in patches of prey already being attacked by their larvae and those on the elytra are used in mate recognition. That different context dependent messages
could be signalled by similar chemicals is an example of semiochemical parsimony.

Borage oil (Borago officinalis L.). An important source of gamma linolenic acid. 1: Compositive characteristics and oxidative stability of oils extracted by different techniques and mixed with extra virgin olive oil.
http://hdl.handle.net/2268/185216
Title: Borage oil (Borago officinalis L.). An important source of gamma linolenic acid. 1: Compositive characteristics and oxidative stability of oils extracted by different techniques and mixed with extra virgin olive oil.
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<br/>Author, coauthor: Sensidoni, A.; Bortolussi, G.; Orlando, C.; Lognay, Georges; Santi, R.; Fantozzi, P.
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<br/>Abstract: The oxidative stability of borage (Borago officinalis L.) oils from commercial origin or extracted by different methods (with solvents and supercritical CO2) was determined by the Rancimat method. To delay theoxidative degradation with the aim of preserving the nutritional characteristics of borage oil, several boragevirgin olive oil blends wereprepared and submitted to analysis. The results indicated that the incorporation of borage in virgin olive oil (to a level not exceeding 50g/kg) while modifying the fatty acid profile of the resulting blends had a limited effect on the oxidative stability provided that the blends were maintained in the absence of light.

Application Of Radiometric And Isotope DilutionMass Spectrometric Techniques To The Certification Of Edible Oil And Fat Reference Materials
http://hdl.handle.net/2268/185215
Title: Application Of Radiometric And Isotope DilutionMass Spectrometric Techniques To The Certification Of Edible Oil And Fat Reference Materials
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<br/>Author, coauthor: Marlier, M.; Lognay, Georges; Wagstaffe, J.; Dreze, P.; Severin, M.
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<br/>Abstract: A method for the isotope dilutionmass spectrometric (IDMS) determination of butyric acid C4 in butter fat (RM164) was developed in order to support the data gathered from nine experienced European laboratories within the final certification exercise. The IDMS results
(3,46 _+ 0,06 g C4/100 g fat) were in very good agreement with those obtained by "classical" GLC and HPLC techniques. (RM164 was finally certified at 3,49 + 0,06 g C4/100 g fat).
This paper reports briefly on a previous preliminary study undertaken to validate a procedure (agreed by the BCRsterol group) for the isolation of the sterol from fats and oils. By use of labelled sterols and radiometric measurements it was shown that sterol recoveries were superior to 96%.