bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self‐Assembly and Characterisation of Grid‐Type Iron(II), Cobalt(II) and Zinc(II) Complexes
Authors: Patroniak Violetta , Baxter Paul N. W. , Lehn Jean‐Marie , Kubicki Maciej , Nissinen Maija , Rissanen Kari 
Published: November 2003

AbstractThe reaction of the ligands 5 and 6, containing two tridentate binding units, with iron(II), cobalt(II) and zinc(II) leads to the self‐assembly of supramolecular architectures of [2 × 2] grid type containing four ions in octahedral coordination sites. The grid‐type structures have been assigned on the basis of the spectroscopic data in solution, and confirmed in the solid state in the case of complexes 6b and 6c by X‐ray crystallography. The latter study revealed that each metal ion is situated in a distorted octahedral coordination environment comprising two N,N,O ligand donor sets. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Novel Complexes of Ligands Containing Phenol and Alcohol Groups: From Polynuclear Cluster, 1D Coordination Polymer to 2D Supramolecular Assemblies
Authors: Xie Yongshu , Liu Qingliang , Jiang Hui , Ni Jia 
Published: November 2003

AbstractA series of CoII, CuII, ZnII, AgI and mixed‐valence cobalt complexes 1−9 with tridentate and tetradentate chelating ligands containing oxygen‐bridging and hydrogen‐bonding groups have been synthesized, four of which have been structurally characterized: [Co6L16(OH)(H2O)3]Cl2·10H2O (1) [H2L1 = N‐(2‐hydroxybenzyl)ethanolamine] is a hexanuclear CoIII3CoII3 complex, with a core of quadruple face‐sharing defective cubane‐like units; [CuNaL2(ClO4)]∞ (3) [H2L2 = N,N′‐bis(2‐hyroxybenzyl)ethylenediamine] is a μ3‐phenoxo‐ and μ4‐perchlorato‐bridged 1D heterometallic CuIINaI coordination polymer; the coordination moieties of [CuL3]4·4H2O (6) [H2L3 = N,N′‐bis(2‐hyroxy‐5‐methylbenzyl)ethylenediamine] form a 2D hydrogen‐bonded network structure of monophenoxo‐bridged dimeric moieties; and the molecules of [Ag(H2L2)(HL2)] (9) are connected to give an undulated 2D structure, consisting of hydrogen‐bonded hexagonal units. The variety of these structures is discussed on the basis of the stereoelectronic preferences of the metal atoms, hydrogen bonds, disposition of the bridging groups, steric effect, and conformational flexibility of the ligands. Variable‐temperature magnetic properties of 1 and 6 are also reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
General Synthesis and Characterization of Monocrystalline Lanthanide Orthophosphate Nanowires
Authors: Zhang Ya‐Wen , Yan Zheng‐Guang , You Li‐Ping , Si Rui , Yan Chun‐Hua 
Published: November 2003

AbstractMonocrystalline LnPO4 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb) nanowires have been prepared in bulk quantities by a simple, facile, and clean solution‐based hydrothermal method at 220−240 °C by finely tuning the acidity of the stock solutions. The length and width of the nanowires were in the range of 1−10 μm and 10−200 nm, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Characterization of the lipid fraction of Niger seeds (Guizotia abyssinica cass.) from different regions of Ethiopia and India and chemometric authentication of their geographical origin
Authors: Marini Federico , Magrì Antonio L. , Marini Domenico , Balestrieri Fabrizio 
Published: November 2003

AbstractThe oil extracted from the seeds of niger (Guizotia Abyssinica), collected from 6 different regions of Ethiopia and India, was characterized in terms of its fatty acid, sterol and triglyceride distribution and of its total tocopherol content. Where available, the results have been compared with those reported in the literature or with data on oils from the same botanical family (Compositae).The analytical data have then been elaborated by supervised pattern recognition techniques (Linear Discriminant Analysis (LDA) and Artifical Neural Network (ANN)) in order to authenticate the geographical origin of the samples. Eight and 11 variables were necessary to achieve a complete discrimination respectively of the country and of the region of origin of the oils under exam, when using LDA, whereas ANN required a smaller number of experimental variables (4 and 6), due to its non‐linearity.
Lipid deterioration during chilled storage of Atlantic pomfret (Brama brama)
Authors: Pérez‐Alonso Francisco , Arias Cristina , Aubourg Santiago P. 
Published: November 2003

AbstractLipid damage produced during Atlantic pomfret (Brama brama) chilled storage (up to 19 d) was studied. The formation of various lipid parameters, such as free fatty acid and conjugated dienes (CD), peroxide value, thiobarbituric acid reactive substances and fluorescent compounds was measured in 2 different white muscle zones (dorsal and ventral). The results were compared with the formation of volatile amines (total volatile base‐nitrogen, TVB‐N, trimethylamine‐nitrogen, TMA‐N). A gradual lipid hydrolysis was observed in both zones during the entire experiment. CD and peroxides formation was prominent during the experiment, whereas peroxides showed the highest value at day 15 in both zones followed by a peroxide breakdown at day 19. Interaction of oxidized lipids with nucleophilic compounds present in the fish muscle led to a gradual development of fluorescent material during storage in both zones. The mean value of the lipid content tended to be higher in the ventral zone than in the dorsal one, although significant differences could not be detected (p >0.05). Concerning the lipid damage, very small differences (p <0.05) could be assessed between both zones. TVB‐N content showed no variation till day 15. At day 19, a sharp increase was observed for both muscle zones. In the case of TMA, a gradual increase was observed in both muscles during the 19‐day storage. Higher mean values of TVB‐N and TMA‐N indices were obtained for the ventral than for the dorsal zone. This might be due to the fact that the ventral zone is close to the viscera, where microorganisms are known to concentrate. Of all the different indices tested for quality assessment, TMA‐N and the formation of fluorescent compounds were strongest related to the duration of storage (r2≥0.87). These might therefore be the most accurate parameters to follow quality loss of chilled Atlantic pomfret.
Extraction of tocopherols from the deodorized distillate of soybean oil with liquefied petroleum gas
Authors: Buczenko Gisele Maria , de Oliveira Juarez Souza , von Meien Oscar Felippe 
Published: November 2003

AbstractDeodorizer distillate, produced during the last processing step of edible oil refinement, is a mixture of tocopherols, sterols, fatty acids, glycerides, hydrocarbons, water and other materials. The amount of tocopherols in deodorizer distillate is large enough to be considered as raw material for vitamin E preparation. In this work, separation of tocopherols from sterols has been achieved using liquefied petroleum gas (LPG) extraction. LPG was chosen as extraction solvent in order to improve extract recovery and prevent tocopherol degradation.
Selective uptake of fatty acids by the yeast Yarrowia lipolytica
Authors: Papanikolaou Seraphim , Aggelis George 
Published: November 2003

AbstractYarrowia lipolytica, when cultivated on mixtures of free fatty acid substrates was found to remove C12:0, C14:0, Δ9C18:1, Δ9, 12C18:2 and Δ9, 12, 15C18:3 at significantly higher rates than C16:0 and C18:0, regardless of fatty acid composition of the initial substrate. C12:0, C14:0 and Δ9, 12, 15C18:3 were specifically and completely removed from the substrate, while Δ9C18:1 and Δ9, 12C18:2 concentrations decreased by 55‐80 wt‐% in comparison with initial concentrations. In contrast, concentration of C18:0 increased 2.1—3.5 fold in the substrate. Although C18:0 was removed slowly from the substrate, this fatty acid was selectively accumulated in the storage lipid. Inversely, only low quantities of Δ9C18:1 and Δ9, 12C18:2 and traces of C12:0, C14:0 and Δ9, 12, 15C18:3 were accumulated in the storage lipid. During storage lipid breakdown, cellular C16:0 and Δ9C18:1 were taken up more rapidly than C18:0. We concluded that the capability of Yarrowia lipolytica to selectively remove several fatty acids from the substrate and accumulate others could be used in modification of the composition of selected mixtures of fatty acids and probably of common fats, to produce “new” fats with a predetermined composition.
Rapid simultaneous determination by proton NMR of unsaturation and composition of acyl groups in vegetable oils
Authors: Guillén María D. , Ruiz Ainhoa 
Published: November 2003

Abstract1H NMR spectra of 66 samples of edible oils from 14 different botanical origins were acquired. Assignment of signal spectra to the different types of hydrogen atoms was made and the areas of the signals determined. Considering that the area of the signals of the spectra is proportional to the number of hydrogen atoms of each type in the sample, it is possible to calculate not only the iodine value, but also the proportion of different acyl groups from the data. Determination of both parameters requires only a few minutes and one spectroscopic run. Classical methodology however, requires two separate wet methods for determining the unsaturation degree (iodine value) and the proportions of different acyl groups; both of them involve chemical transformations of the sample and considerable time and cost. Determination of acyl group proportions in samples by 1H NMR, which was validated with mixtures of standard triglycerides, provides accurate results and is able to detect small differences between samples of very similar composition.
Lipase‐catalyzed alcoholysis of vegetable oils
Authors: Soumanou Mohamed M. , Bornscheuer Uwe T. 
Published: November 2003

AbstractFatty acid alkyl esters were produced from various vegetable oils by transesterification with different alcohols using immobilized lipases. Using n‐hexane as organic solvent, all immobilized lipases tested were found to be active during methanolysis. Highest conversion (97%) was observed with Thermomyces lanuginosa lipase after 24 h. In contrast, this lipase was almost inactive in a solvent‐free reaction medium using methanol or 2‐propanol as alcohol substrates. This could be overcome by a three‐step addition of methanol, which works efficiently for a range of vegetable oils (e.g. cottonseed, peanut, sunflower, palm olein, coconut and palm kernel) using immobilized lipases from Pseudomonas fluorescens (AK lipase) and Rhizomucor miehei (RM lipase). Repeated batch reactions showed that Rhizomucor miehei lipase was very stable over 120 h. AK and RM lipases also showed acceptable conversion levels for cottonseed oil with ethanol, 1‐propanol, 1‐butanol and isobutanol (50‐65% conversion after 24 h) in solvent‐free conditions. Methyl and isopropyl fatty acid esters obtained by enzymatic alcoholysis of natural vegetable oils can find application in biodiesel fuels and cosmetics industry, respectively.
Solvent‐Free Microwave‐Assisted Efficient Synthesis of 4,4‐Disubstituted 2‐Oxazolines
Authors: García‐Tellado Fernando , Loupy André , Petit Alain , Marrero‐Terrero Alma Leilani 
Published: November 2003

Abstract4,4‐Disubstituted 2‐oxazolines have been synthesized by a microwave‐promoted solvent‐free direct condensation of carboxylic acids and disubstituted β‐amino alcohols in good to excellent yields. Zinc oxide is a very good solid support in cases where a Lewis acid is required. The method described herein is a very good, safe, clean, economical, and environmentally friendly alternative to the classical procedures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Selenium‐Promoted Oxidation of Organic Compounds: Reactions and Mechanisms
Authors: Młochowski Jacek , Brząszcz Monika , Giurg Mirosław , Palus Jerzy , Wójtowicz Halina 
Published: November 2003

AbstractOxidation reactions are fundamental processes widely applied in organic synthesis. Elemental selenium and more often its compounds have been successfully used as stoichiometric reagents and catalysts for oxidation of different organic substrates. Selenium(IV) oxide, areneseleninic acids and their anhydrides are widely used as stoichiometric oxidants or as oxygen‐transfer agents for oxygen donors, particularly hydrogen peroxide andtert‐butyl hydroperoxide. Organic diselenides (the precursors of seleninic acids) have been used as oxidation catalysts while dimethyl and diphenyl selenoxides are stoichiometric oxidants. Selenenamides, such as 2‐phenyl‐1,2‐benzisoselenazol‐3(2H)‐one (ebselen) and its analogues, known as glutathione peroxidase mimics acting via active hydroperoxide intermediates, are efficient and selective oxidation catalysts. Selenium(IV) oxide and some organoselenium compounds have been successfully applied for various oxidations useful in practical organic syntheses such as epoxidation, 1,2‐dihydroxylation, and α‐oxyfunctionalization of alkenes as well as for ring contraction of cycloalkanones, conversion of halomethyl, hydroxymethyl, or active methylene groups into formyl groups, oxidation of aldehydes into carboxylic acids, sulfides into sulfoxides, and secondary amines into nitrones, regeneration of parent carbonyl compounds from their azomethine derivatives and for other reactions. The oxidation mechanisms depend on the substrate and oxidant or catalyst used. The electrophilic center localized on the selenium atom or the nucleophilic center localized on the oxygen atom of the selenahydroperoxide group are involved in the reaction mechanism. In both cases the selenium‐containing moiety is a good leaving group. Exceptionally oxidation can proceed via free radical selenium species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Potassium Trifluoro(organo)borates: New Perspectives in Organic Chemistry
Authors: Darses Sylvain , Genet Jean‐Pierre 
Published: November 2003

AbstractPotassium trifluoro(organo)borates, highly stable organoboron derivatives, have recently emerged as promising alternatives to other organoboron reagents. These salts have shown interesting reactivity, not only through the intermediate formation of difluoroboranes, but also in transmetallation reactions with transition metals. In numerous reactions they have proven to be more reactive than boronic acids or esters. The preparation and reactivity of these ate complexes is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis of 1′‐Homo‐N‐nucleosides from Hexitols
Authors: Saladino Raffaele , Ciambecchini Umberto , Hanessian Stephen 
Published: November 2003

AbstractThis paper describes a new route for the synthesis of N‐(1′‐homo‐L‐gulitol)nucleosides and amino sugar analogues of N‐(1′‐homo‐L‐gulitol)nucleosides by nucleophilic epoxide ring‐opening followed by O‐heterocyclization of 1,2:5,6‐dianhydro‐3,4‐di‐O‐benzyl‐D‐mannitol and 1,2:5,6‐dianhydro‐3,4‐diazido‐D‐iditol, respectively. Magnesium perchlorate [Mg(ClO4)2] was found to be the best catalyst for the reaction of silylated bases, derived from uracil, thymine and adenine, with these bis(epoxides). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Novel Biodegradable Pyridinium Amphiphiles for Gene Delivery
Authors: Pijper Dirk , Bulten Erna , Šmisterová Jarmila , Wagenaar Anno , Hoekstra Dick , Engberts Jan B. F. N. , Hulst Ron 
Published: November 2003

AbstractBiodegradable synthetic cationic pyridinium‐based amphiphiles (SAINTs) prove to be promising non‐viral carrier systems for delivery of DNA into eukaryotic cells. Six novel SAINTs were synthesised from 3,5‐pyridinedicarboxylic acid as starting material, with two ester groups as linkers between the cationic headgroup and the hydrophobic tails. The vesicle‐forming properties of the amphiphiles were studied by differential scanning calorimetry and transmission electron microscopy, whereas the hydrolysis of the diesters in water was investigated by NMR spectroscopy. Finally, the transfection potential and cytotoxicity were determined on COS‐7 and HepG‐2 cells in culture. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Aldol Reaction under High‐Intensity Ultrasound: A Novel Approach to an Old Reaction
Authors: Cravotto Giancarlo , Demetri Alberto , Nano Gian Mario , Palmisano Giovanni , Penoni Andrea , Tagliapietra Silvia 
Published: November 2003

AbstractWe have employed high‐intensity ultrasound (HIU) to reinvestigate the aldol reaction (AR) in water. A number of aldols that under usual conditions would undergo elimination were isolated in acceptable to good yields. Within 15−30 min, acetophenone reacted with non‐enolizable aldehydes to afford the aldol exclusively, while under conventional conditions (stirring or heating under reflux) the same compounds either failed to react or gave, after several hours, the enone, often in complex product mixtures. A library of polyols was obtained starting from a series of acetophenones and excess formaldehyde. Benzaldehyde reacted with a series of 1,3‐dicarbonyl compounds to afford the corresponding bis(benzylidene) adducts. The results proved to be highly reproducible because the relevant sonochemical parameters were rigorously controlled. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Glycerol and Glycerol Glycol Glycodendrimers
Authors: Boysen Mike M. K. , Elsner Katharina , Sperling Oliver , Lindhorst Thisbe K. 
Published: November 2003

AbstractNon‐covalent interactions between structural parts of complex oligosaccharides and saccharide‐recognising proteins are of crucial importance for many cell communication phenomena. Specificity of such interactions and stability of these ligand‐receptor complexes are achieved through multivalent interactions between multiple copies of a saccharide ligand and a corresponding number of protein receptors. Substances presenting multiple copies of the saccharide ligand on easily accessible scaffold molecules therefore appear to be promising tools for study of multivalent interactions and their possible inhibition. Such multivalent glycomimetics can be prepared by attachment of saccharide residues to the surface functional groups of dendrimers. In the course of our work, we have prepared novel glycodendrimers with glycerol and glycerol glycol polyether scaffolds. Isopropylidene‐protected hydroxyethyl mannoside was chosen as the carbohydrate component, with the construction of the dendritic structures proceeding by a convergent approach featuring iterative Williamson etherification and ozonolysis/hydride reduction steps. Deprotected representatives of such structures are potential inhibitors of mannose‐binding lectins of E. coli. Three representative compounds were deprotected and their anti‐adhesive properties were examined. The route to these glycodendrimers was also evaluated in terms of synthetic chemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Evaluation of RNA messengers involved in lipid trafficking of human intestinal cells by reverse‐transcription polymerase chain reaction with competimer technology and microchip electrophoresis
Authors: Cantàfora Alfredo , Blotta Ida , Rivabene Roberto , Pisciotta Livia , Bertolini Stefano 
Published: November 2003

AbstractWe developed a semiquantitative reverse‐transcription polymerase chain reaction (RT‐PCR) procedure based on the combination of competimer technology with microchip electrophoresis. The approach was applied to total RNA extracts from the human colon carcinoma cell line CaCo‐2 cultured for 22 days onto tissue plate inserts that allow the polarized cell growth. At time of experiment these cells were incubated for 2 h with lipid micelles containing either cholesterol or a mixture cholesterol/β‐sitosterol or serum‐free Dulbecco's modified Eagle medium (DMEM) alone. Total RNA was extracted from cell pellets by silica membrane spin columns and reverse‐transcribed by a genetically engineered M‐MuLV enzyme and an oligo (dT)15 primer. The cDNA underwent PCR amplification for the following genes: apolipoprotein A1 (ApoAI), apolipoprotein E (ApoE), ATP‐binding cassette A1 (ABCA1), liver X receptor α (LXRα) and farnesoid X receptor (FXR). The β‐actin gene, used as an endogenous reference, was coamplified with mixtures of primer and competimer at a ratio leading to a reference band of intensity comparable to that of the gene under analysis. Amplification products were separated and quantitated by microchip electrophoresis in order to determine, for each gene, the optimum cycle numbers and primer to competimer ratios for the β‐actin therefore used for evaluating the relative variations of gene expressions in the different experiments. The incubation with cholesterol micelles stimulated both LXR and FXR expression that was accompanied by an increased expression of ABCA1 and ApoAI genes (1.4‐ and 1.5‐fold, respectively) and halved the APOE expression. The effect on ABCA1 and ApoAI expression was even stronger (5.7‐ and 2.6‐fold, respectively) with β‐sitosterol‐containing micelles. Similar changes are in line with previous findings and suggest that the short incubation with β‐sitosterol‐enriched micelles stimulates a specific mechanism that, via ABCA1 activation, can increase the cholesterol and phytosterol basolateral efflux.
Microfluidic devices fabricated in Poly(dimethylsiloxane) for biological studies
Authors: Sia Samuel K. , Whitesides George M. 
Published: November 2003

AbstractThis review describes microfluidic systems in poly(dimethylsiloxane) (PDMS) for biological studies. Properties of PDMS that make it a suitable platform for miniaturized biological studies, techniques for fabricating PDMS microstructures, and methods for controlling fluid flow in microchannels are discussed. Biological procedures that have been miniaturized into PDMS‐based microdevices include immunoassays, separation of proteins and DNA, sorting and manipulation of cells, studies of cells in microchannels exposed to laminar flows of fluids, and large‐scale, combinatorial screening. The review emphasizes the advantages of miniaturization for biological analysis, such as efficiency of the device and special insights into cell biology.
Electrophoretic microchip with dual‐opposite injection for simultaneous measurements of anions and cations
Authors: Wang Joseph , Chen Gang , Muck Alexander , Collins Greg E. 
Published: November 2003

AbstractA novel dual‐injection poly(methylmethacrylate) (PMMA) microchip electrophoretic system has been designed and fabricated for simultaneous measurements of anions and cations using a single channel and detection device. It consists of two sample reservoirs, on both sides of a common separation channel. Anions and cations can be simultaneously electrokinetically injected into both ends of the separation channel. Due to lower electroosmotic flow in polymer channels compared to glass ones, the cations and anions migrate in opposite directions and can be separated from each other and detected using a movable contactless conductivity detector (MCCD) positioned around the center of the separation channel. The effects of the detector position and of the separation voltage on the response and resolution have been studied and optimized for simultaneous determination of six low‐energy explosive‐related ions, including ammonium, methyl ammonium, sodium, chloride, nitrate, and perchlorate in a single analytical run (of ca. 3 min). Simultaneous detection of nerve‐agent degradation products along with explosive‐related anions and cations is also demonstrated. The versatile system can also be used for separately measuring anions or cations. The attractive behavior of the dual‐opposite injection microchip offers great promise for a wide range of applications, including “total ion analysis” of various samples.