bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational estimation of the triacylglycerol composition of vegetable fats from gas and liquid chromatography data
Authors: van Vliet Martin H. , van Kempen Geert M. P. 
Published: October 2004

AbstractA mathematical framework was described and discussed that relates the triacylglycerol (TAG) distribution to measurements results. This model is valid for any analytical technique for which an unambiguous relation between the TAGs and the experimental data exists. The framework can be employed to estimate the TAG distribution based on any subset of these analytical techniques. Furthermore future techniques can be incorporated, eventually enabling the computation of the exact TAG distribution.In current practice the relation from measurement values to the TAG distribution is believed to be described byColeman's theory. However some natural fats and fractions of fats are known to be non‐adherent toColeman's theory. For both palm stearin and palm kernel oil this notion is tested and confirmed. For these fats a different approach is needed to be able to estimate the TAG distribution.Within the framework three different approaches for making an estimation of the TAG distribution based on measured data are described, discussed and compared withColeman's results: a least squares approach, a genetic algorithm (GA) approach and an expectation maximisation (EM) approach. The results presented demonstrate that the estimated TAG distributions from the GA and EM algorithm are significantly better thanColeman's estimate and the least squares approach. Overall the EM algorithm is favoured because of its consistency.
Chemical and enzymatic interesterification of a beef tallow and rapeseed oil equal‐weight blend
Authors: Kowalski Boleslaw , Tarnowska Katarzyna , Gruczynska Eliza , Bekas Witold 
Published: October 2004

AbstractA mixture of beef tallow and rapeseed oil (1:1, wt/wt) was interesterified using sodium methoxide or immobilized lipases from Rhizomucor miehei (Lipozyme IM) and Candida antarctica (Novozym 435) as catalysts. Chemical interesterifications were carried out at 60 and 90 °C for 0.5 and 1.5 h using 0.4, 0.6 and 1.0 wt‐% CH3ONa. Enzymatic interesterifications were carried out at 60 °C for 8 h with Lipozyme IM or at 80 °C for 4 h with Novozym 435. The biocatalyst doses were kept constant (8 wt‐%), but the water content was varied from 2 to 10 wt‐%. The starting mixture and the interesterified products were separated by column chromatography into a pure triacylglycerol fraction and a nontriacylglycerol fraction, which contained free fatty acids, mono‐, and diacylglycerols. It was found that the concentration of free fatty acids and partial acylglycerols increased after interesterification. The slip melting points and solid fat contents of the triacylglycerol fractions isolated from interesterified fats were lower compared with the nonesterified blends. The sn‐2 and sn‐1,3 distribution of fatty acids in the TAG fractions before and after interesterification were determined. These distributions were random after chemical interesterification and near random when Novozym 435 was used. When Lipozyme IM was used, the fatty acid composition at the sn‐2 position remained practically unchanged, compared with the starting blend. The interesterified fats and isolated triacylglycerols had reduced oxidative stabilities, as assessed by Rancimat induction times. Addition of 0.02% BHA and BHT to the interesterified fats improved their stabilities.
Modified ferrous oxidation‐xylenol orange method to determine lipid hydroperoxides in fried snacks
Authors: Navas José A. , Tres Alba , Codony Rafael , Boatella Josep , Bou Ricard , Guardiola Francesc 
Published: October 2004

AbstractA modified ferrous oxidation‐xylenol orange (FOX) method was adapted to measure lipid hydroperoxides (LHP) in lipid extracts from snack foods fried in vegetable oils. First, a methanol‐based FOX reaction medium was assayed, but this became turbid upon addition of the lipid extracts dissolved in ethanol. To avoid the precipitation of lipids, the polarity of the reaction medium was reduced by lowering its water content and by replacing the methanol as the basis of the medium for less polar solvents. Some of the solvents used instead of methanol yielded a lower FOX reaction response. Of the reaction media assayed, the one based on dichloromethane/ethanol (3:2, vol/vol) was not turbid at high lipid extract concentrations (assayed at up to 25 mg of lipid extract/mL reaction medium) and provided the same response level as the methanol‐based medium. Thus, this FOX method shows high sensitivity and is particularly useful for lipid extracts with low LHP content. This method was also successfully applied to edible oils. Solvents such as 2‐propanol, ethyl acetate and butanol were discarded, because they easily produce hydroperoxides, which interfere in the FOX reaction. Xylenol orange preparations from a number of suppliers were tested, and some differences affecting the sensitivity of the reaction were observed.
Monitoring of 2,4‐decadienal in oils and fats used for frying in restaurants in Athens, Greece
Authors: Andrikopoulos Nikolaos K. , Chiou Antonia , Mylona Anastasia , Boskou George , Dedoussis George V. Z. 
Published: October 2004

AbstractSome frying by‐products of medium polarity, so‐called medium‐polarity materials (MPM), produced during domestic deep‐frying of French‐fried potatoes in edible vegetable oils, have recently been isolated and linearly correlated to % total polar materials and % polymerized triglycerides. The in vitro oxidation of low‐density lipoproteins in a dose‐dependent manner by MPM has also been reported. In the present study, the MPM constituents were identified after extraction of MPM from the oils, subsequent purification by RP‐HPLC, and GC‐MS analysis. The main constituent of MPM was trans,trans‐2,4‐decadienal, a compound that has previously been reported to be formed during peroxidation of linoleic and arachidonic acid. 2,4‐Decadienal was also quantified in oils and fats used for frying in restaurants in Athens, Greece, by direct injection of oil sample solutions in HPLC. For the most commonly used frying oils, 2,4‐decadienal concentration ranges were 0.3–119.7 mg/kg for sunflower oil, 13.3–92.7 mg/kg for cottonseed oil, 4.1–44.9 mg/kg for palm oil, and 2.0–11.3 mg/kg for vegetable cooking fats. Considering the common catering practices of frying, 2,4‐decadienal was more likely to be found in sunflower oil after deep‐frying of potatoes. Comparing the amounts of this aldehyde found in oils from restaurants to the amounts previously found for domestic frying (up to 30 mg/kg after the 8th successive frying session in sunflower oil), the probability of consuming a level of 2,4‐decadienal in restaurant‐prepared food that is higher than the level in home‐fried food was determined to be approximately one third.
Formation of hydroperoxy‐ and hydroxyalkenals during thermal oxidative degradation of sesame oil monitored by proton NMR
Authors: Guillén María D. , Ruiz Ainhoa 
Published: October 2004

AbstractThe usefulness of 1H nuclear magnetic resonance (NMR) for studying oil oxidation processes was tested. Refined sesame oil was submitted to oxidative conditions at 70 °C with circulating air, and the status of the sample was studied daily by 1H NMR. This technique permits the determination of the proportions of the acyl groups in the oil throughout the oxidation process and, at the same time, allows monitoring of the formation and degradation of primary oxidation compounds, as well as of the formation of secondary oxidation products. Generation of the geno‐ and cyto‐toxic oxygenated aldehydes 4‐hydroxy‐, 4‐hydroperoxy‐ and 4,5‐epoxy‐trans‐2‐alkenal was proved.
Synthesis of Gold Glyconanoparticles: Possible Probes for the Exploration of Carbohydrate‐Mediated Self‐Recognition of Marine Sponge Cells
Authors: de Souza Adriana Carvalho  , Halkes Koen M. , Meeldijk Johannes D. , Verkleij Arie J. , Vliegenthart Johannes F. G. , Kamerling Johannis P. 
Published: October 2004

AbstractThe first step in marine sponge cell recognition and adhesion operates via a calcium‐dependent proteoglycan− proteoglycan interaction. For the marine sponge Microciona prolifera, one of the carbohydrate epitopes involved in the proteoglycan self‐recognition is a sulfated disaccharide [GlcpNAc3S(β1−3)Fucp]. Earlier surface plasmon resonance studies have demonstrated that the proteoglycan self‐recognition can be mimicked with synthetic β‐D‐GlcpNAc‐(1→3)‐α‐L‐Fucp‐(1→O), when multivalently presented by conjugation with bovine serum albumin. Here, the straightforward synthesis of water‐soluble gold glyconanoparticles coated with the glycosides β‐D‐GlcpNAc3S‐(1→3)‐α‐L‐Fucp‐(1→O)(CH2)3S(CH2)6SH, β‐D‐GlcpNAc3S‐(1→3)‐β‐L‐Fucp‐(1→O)(CH2)3S(CH2)6SH, β‐D‐GlcpNAc3S‐(1→O)(CH2)3S(CH2)6SH, α‐L‐Fucp‐(1→O)(CH2)3S(CH2)6SH, β‐D‐Glcp‐NAc3S‐(1→3)‐α‐L‐Galp‐(1→O)(CH2)3S(CH2)6SH, β‐D‐Glcp‐NAc‐(1→3)‐α‐L‐Fucp‐(1→O)(CH2)3S(CH2)6SH, and β‐D‐Glcp3S‐(1→3)‐α‐L‐Fucp‐(1→O)(CH2)3S(CH2)6SH is presented. Such supramolecular structures are excellent probes for studying carbohydrate−carbohydrate interactions by transmission electron microscopy, thereby generating information on the molecular level about the role of different functionalities in the self‐recognition process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Regioselectively N‐Functionalised 14‐Membered Azapyridinomacrocycles Bearing Trialkanoic Acid Side Chains as Ligands for Lanthanide Ions
Authors: Dioury Fabienne , Sylvestre Isabelle , Siaugue Jean‐Michel , Wintgens Véronique , Ferroud Clotilde , Favre‐Réguillon Alain , Foos Jacques , Guy Alain 
Published: October 2004

AbstractFour 14‐membered azamacrocycles 2a−d, each containing a pyridine moiety and three acetic and/or propionic acid pendent arms, were prepared from regioselectively functionalised polyamines. The stability constants of the lanthanide complexes (La, Pr, Nd, Eu, Gd, Tb, Er, Yb, Lu) formed with the triacetic acid compound 2a were determined by spectroscopic methods (luminescence and/or UV/Vis spectroscopy). Other characteristics of the luminescent EuIII and TbIII complexes formed with the triacetic acid derivative 2a were also evaluated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Alternative and Chemoselective Deprotection of the α‐Amino and Carboxy Functions ofN‐Fmoc‐Amino Acid andN‐Fmoc‐Dipeptide Methyl Esters by Modulation of the Molar Ratio in the AlCl3/N,N‐Dimethylaniline Reagent System
Authors: Di Gioia Maria Luisa , Leggio Antonella , Le Pera Adolfo , Liguori Angelo , Perri Francesca , Siciliano Carlo 
Published: October 2004

AbstractThe amino and carboxy functions inN‐Fmoc‐α‐amino acid andN‐Fmoc‐peptide methyl esters can be alternatively and chemoselectively deprotected by treatment with the reagent system AlCl3/N,N‐dimethylaniline (DMA). The chemoselectivity of the process is controlled by modulating the relative molar ratio of the Lewis acid and DMA. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Diastereoselective Synthesis of Thieno[3′,2′:4,5]cyclopenta[1,2‐d][1,3]oxazolines − New Ligands for the Copper‐Catalyzed Asymmetric Conjugate Addition of Diethylzinc to Enones
Authors: Bonini Bianca Flavia , Capitò Elena , Comes‐Franchini Mauro , Ricci Alfredo , Bottoni Andrea , Bernardi Fernando , Miscione Gian Pietro , Giordano Laurent , Cowley Andrew R. 
Published: October 2004

AbstractSeveral new ligands featuring a rigid three ring skeleton have been prepared for the first time following a modular approach. Chirality has been introduced by use of an oxazoline moiety fused with a cyclopenta[b]thiophene backbone. The efficiency and stereochemical impact of these ligands on the copper‐catalyzed enantioselective addition of Et2Zn to chalcone was examined and enantiomeric excesses up to 79% were achieved using the ligand (R,R)‐16 substituted with a methyl group at the cyclopenta moiety. Computational and ESI‐mass spectral studies show that these new compounds behave as monodentate ligands towards Cu+. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Activity of Adenosine Deaminase (ADA) and Adenylate Deaminase (AMPDA) Towards 6‐Chloropurine Nucleosides Modified in the Ribose Moiety
Authors: Ciuffreda Pierangela , Buzzi Benedetta , Alessandrini Laura , Santaniello Enzo 
Published: October 2004

AbstractThe enzymes adenosine deaminase (ADA) and adenylate deaminase (AMPDA) are able to catalyze the hydrolytic dechlorination of 6‐chloropurine riboside and the corresponding 2′,3′‐O‐isopropylidene derivative, but show no activity towards the 3,4‐O‐isopropylidene‐1‐methylriboside of 6‐chloropurine and adenine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Solid‐State Structure and Tautomerism of 2‐Aminotroponimines Studied by X‐ray Crystallography and Multinuclear NMR Spectroscopy
Authors: Claramunt Rosa M. , Sanz Dionisia , Pérez‐Torralba Marta , Pinilla Elena , Torres M. Rosario , Elguero José 
Published: October 2004

AbstractStructural studies in the solid state by X‐ray crystallography and by 13C and 15N CPMAS NMR spectroscopy carried out on a series of 2‐aminotroponimine derivatives 2−5 has allowed to establish the existence of hydrogen bonding and to determine the most stable tautomer. Almost all the structures reflect the classical double‐well potential function for the N−H···N hydrogen bonds. Only in the case of the compound N‐(pyrrol‐1‐yl)‐2‐(pyrrol‐1‐ylamino)troponimine (5) the crystal structure shows two independent molecules, one with a classical hydrogen bond and another with either a single‐well or a low‐barrier hydrogen bond. The structure of this compound is discussed with the use of the solid‐state NMR spectroscopic data. 2‐Aminotropones, as intermediates to the 2‐aminotroponimines, show the oxo‐tautomer as the stable form. B3LYP/6‐31G* calculations are used to rationalise the experimental results. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Neutral and Ionic Supramolecular Structures of Unsaturated Dicarboxylic Acids and Acridine: Significance of Molecular Geometry and Proton Transfer
Authors: Mei Xuefeng , Wolf Christian 
Published: October 2004

AbstractSix supramolecular structures exhibiting distinct architectures have been prepared from acridine and different dicarboxylic acids. The co‐crystallization of acridine (1) and configurational isomers of dicarboxylic acids such as cis,trans‐muconic (a) and trans,trans‐muconic acid (b), or fumaric (c) and maleic acid (d) provided strikingly different packing motifs and properties. The supramolecular structures have been rationalized based on the molecular geometry and the constituent synthons. Co‐crystallization of acridine and b, c, or terephthalic acid (e) gave neutral assemblies stabilized by the O‐H···N hydrogen‐bond synthon I. Acridine was found to undergo proton transfer with a, d, and acetylenedicarboxylic acid (f) to form ionic supramolecular structures exhibiting synthon II, i.e. charge‐assisted carboxylate‐acridinium O−···H−N+‐hydrogen bonding. The packing mode of 1+·a− has been inferred from the corresponding acridine‐isophthalic acid analog based on the superimposable structure of the acids and the common charge‐assisted hydrogen bonding motif. Acetylenedicarboxylic and cis,trans‐muconic acid favor the formation of antiparallel acridinium π‐stacks stabilized by alternating hydrogen bonds with two infinite anionic chains of dicarboxylic acids that also undergo head‐to‐tail hydrogen bonding. Because of their different structure and geometry, b, c, d, and e form less uniform packing arrangements with 1. Fumaric and trans,trans‐muconic acid afford 2:1 neutral co‐crystals with parallel acridine rings that are stabilized by π−π‐interactions, whereas terephthalic acid favors association of antiparallel acridine dimers to adopt a different one‐dimensional network. By contrast, d undergoes intramolecular hydrogen bonding which leaves only one carboxyl group available to form a 1:1 ionic supramolecular structure with 1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
7‐(Dimethylamino)tricyclo[5.2.2.01,6]undecene Derivatives from β‐Cyclohexenyl β‐Dimethylamino‐Substituted α,β‐Unsaturated Fischer Carbenes
Authors: Wu Yao‐Ting , Labahn Thomas , Demeter Attila , Zachariasse Klaas A. , de Meijere Armin 
Published: October 2004

AbstractWhen heated in pyridine at 80 °C, pentacarbonyl[(2E)‐3‐cyclohexenyl‐3‐(dimethylamino)‐1‐ethoxy‐2‐propen‐1‐ylidene]chromium (1‐Cr) and ‐tungsten (1‐W) complexes undergo 6π‐electrocyclization and subsequent reductive elimination to yield the cyclohexane‐annelated cyclopentadiene 6, which equilibrates by 1,5‐hydrogen shift with its more reactive isomer 7. The latter molecule is efficiently trapped in Diels−Alder reactions with various alkynes 2 and styrenes 8 to give the cyclohexane‐annelated norbornadiene 3 and norbornene derivatives respectively, with high regio‐ and diastereoselectivity in 15−91% yields. The enol ether moiety in compound 3 is particularly easily hydrolyzed, probably due to the through‐space interaction between the two double bond moieties, so that the norbornenone derivatives 4 are isolated in all but one case after chromatographic purification. In this reaction, the tungsten complex 1‐W consistently gave lower yields than 1‐Cr. Arylalkynes with strongly electron‐withdrawing groups and minimal steric congestion are particularly suitable reaction partners for 7. The formation of bis‐cycloadducts 10 from suitable diynes largely depends upon the steric and electronic properties of the corresponding alkynyl‐substituted mono‐cycloaddition products of type 4 or 11. With the fluorenyl‐substituted tricycle 4w in acetonitrile at 25 °C, but not with 4y, dual fluorescence is observed, with a red‐shifted unstructured additional emission band with a dipole moment of 32 D, originating from intramolecular charge transfer. The molecule 2y has an exceptionally large radiative rate constant of 13 × 108 s−1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Asymmetric Synthesis of 2‐Mono‐ and 2,3‐trans‐Disubstituted Azetidines
Authors: Enders Dieter , Gries Jörg , Kim Zin‐Sig 
Published: October 2004

AbstractA versatile and efficient asymmetric synthesis of 2‐mono‐ and 2,3‐trans‐disubstituted azetidines with excellent diastereomeric (de= 93 to ⩾ 96%) and enantiomeric excesses (ee⩾ 96%) in good overall yields is described. Virtually stereoisomerically pure differentlyN,O‐protected 3‐amino‐1‐alkanols were prepared as intermediates. Key steps are a diastereoselective α‐alkylation of aldehyde SAMP‐hydrazones with benzyloxymethyl chloride as the electrophile, and a nucleophilic 1,2‐addition of various organocerium reagents to the hydrazone CN double bond. An epimerisation‐free reductive removal of the auxiliary gaveO‐benzyl‐protected 3‐amino‐1‐alkanols. AfterN‐tosylation and hydrogenolytic cleavage of the benzylic protecting group, ring closure to the correspondingN‐tosylazetidines was achieved in good yields under Mitsunobu conditions. Detosylation was easily accomplished employing sodium/naphthalene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Convergent Syntheses of N‐Boc‐Protected (2S,4R)‐4‐(Z)‐Propenylproline and 5‐Chloro‐1‐(methoxymethoxy)pyrrol‐2‐carboxylic Acid − Two Essential Building Blocks for the Signal Metabolite Hormaomycin
Authors: Zlatopolskiy Boris D. , Kroll Hans‐Peter , Melotto Elisa , de Meijere Armin 
Published: October 2004

AbstractAn efficient and scalable synthesis of enantiomerically pure N‐Boc‐protected 4‐(Z)‐propenylproline (15) using the conventional Wittig reaction to construct the double bond has been developed [11% yield over 8 steps from N‐Boc‐protected (2S,4R)‐4‐hydroxyproline, 7]. The O‐MOM‐protected 5‐chloro‐1‐hydroxypyrrole‐2‐carboxylic acid [Chpca(MOM)‐OH (29)] was prepared along a reasonably efficient synthetic route applying the thermal rearrangement of 2‐azido‐6‐chloropyridine N‐oxide (22) as a key step in fairly good overall yield [9% over 7 steps from easily accessible 2,6‐dichloropyridine N‐oxide (21)]. The suitability of the MOM‐protected N‐hydroxy group during the preparation of the N‐hydroxypyrroles functionalized at C‐2, was confirmed by the successful synthesis of Chpca‐(3‐Ncp)Ala‐OFM 33 obtained from the acylated amino ester Chpca(MOM)‐(3‐Ncp)Ala‐OFM 32, which was selectively deprotected leaving the sensitive N‐hydroxypyrrole unit intact. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Synthesis of Ventiloquinone F and Isoventiloquinone F as Racemates
Authors: Giles Robin G. F. , Green Ivan R. , van Eeden Nestor 
Published: October 2004

AbstractRacemic ventiloquinone F and isoventiloquinone F have been synthesized utilizing an initial Stobbe condensation, followed by mercury(II)‐mediated ring closure and catalytic hydrogenolysis as key steps in the synthetic protocol. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Measuring the amount of statistical information in the EPT index
Authors: Kitchin Patty L. 
Published: October 2004

AbstractBiological monitoring is the process of measuring the effect of environmental stress on the environment. Aquatic macroinvertebrates are widely used in the monitoring of freshwater lotic systems. The macroinvertebrate fauna of a reference stream is commonly compared to the fauna of an impacted stream that is affected by an environmental stressor. The smaller the similarity between these two streams, the greater the effect of pollution or stress on the impacted stream. Many richness measures, or statistics, exist for measuring similarity. These statistics can be computed using different levels of taxonomic resolution (species, genus and family). Many aquatic biologists believe that species‐level identifications, which require exorbitant time and expertise, are needed for correct data interpretations. The actual amount of information provided by these statistics at different taxonomic levels has never been measured. This article evaluates the amount of statistical information provided by the EPT index as compared to a sufficient statistic at the various levels of taxonomic resolution. Copyright © 2004 John Wiley & Sons, Ltd.
Testing information redundancy in environmental monitoring networks
Authors: Sarno Emma 
Published: October 2004

AbstractThere is a vast literature on optimal monitoring network designs. Most proposals arise from spatial statistics and they often overlook the time dimension of data collected by environmental detectors. In this work, we introduce a new concept of optimal design based on information redundancy, employing a time series approach. We model data generating processes corresponding to monitoring stations by ARIMA models and, subsequently, we measure the structural discrepancy between such models with the autoregressive distance estimator. Therefore, within a probabilistic framework we seek significant differences between models and, applying graph theory, we show how to elicit the optimal network design. Finally, a case study regarding the air monitoring network of Rome is illustrated to show how the whole procedure works in practice. Copyright © 2004 John Wiley & Sons, Ltd.