bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colour in folklore and tradition—The principles
Authors: Hutchings John 
Published: December 2003

AbstractHuman beings use colour to manipulate their personal appearance and environment. A large part of this usage falls within the area of oral tradition and ritual that have been handed down within families, tribes or geographical areas. The resulting images are part of our culture; they are activities that give us feelings of belonging and of doing the ‘right thing’. Two surveys were designed to learn more of these very human activities. The first centered on Britain and Ireland; the other was international. Three major driving forces were found for the use of colour in folklore and symbolism—economic, historical and social. The Principle of Adaptation of Physical Resources accounts for the choice of mourning colours of most countries. Colour usage in death echoes the three approaches to mourning of sadness, joy (for the life of the dead), and fear of the spirits of the dead. The Principle of Adaptation of Ideas accounts for regional variations in colour folklore. This embodies a Darwinian‐type principle of behavior, that is, “to survive within a community a belief must have relevance to that community.” A major principle of folk medicine involving colour is the Principle of curing like with like. There are four Principles of Colour Selection in folklore—by the contrast displayed, as a transfer from the perceived or actual usefulness of the colour, by association, and by availability. Green above all colours has especial significance both in the UK and Ireland. In everyday language it is the Principle of Singularity that controls use of colour words as symbols. The biological mechanism permitting these many and contrasting uses of colour depends on the fact that colour is a perception, not the property of an object. That is, a colour can ‘mean’ whatever we wish it to ‘mean’. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 57–66, 2004; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/col.10212
Effects of hue, saturation, and brightness: Part 2: Attention
Authors: Camgöz Nilgün , Yener Cengiz , Güvenç Dilek 
Published: December 2003

AbstractThis is the second part of an experiment by Camgöz, Yener and Güvenç, which investigates attention responses for foreground‐background colour relationships. One hundred and twenty three university undergraduates in Ankara, Turkey, viewed eight background colours selected from HSB colour space, on which colour squares of differing hues, saturations, and brightness's were presented. Participants were asked to show the colour square attracting the most attention on the presented background colour. Findings showed that on any background colour, colours of maximum saturation and brightness attract the most attention (67%). The yellow‐green, green, and cyan range attracts the most attention (45%), followed by the red and magenta range (30%). Foreground‐background colour relationships in terms of attention are also included in the findings of the study. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 20–28, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10214
Mechanisms of the Aerobic Oxidation of Alcohols to Aldehydes and Ketones, Catalysed under Mild Conditions by Persistent and Non‐Persistent Nitroxyl Radicals and Transition Metal Salts − Polar, Enthalpic, and Captodative Effects
Authors: Minisci Francesco , Recupero Francesco , Cecchetto Andrea , Gambarotti Cristian , Punta Carlo , Faletti Roberta , Paganelli Roberto , Pedulli Gian Franco 
Published: December 2003

AbstractThe oxidation of alcohols to aldehydes and ketones by air or oxygen under mild conditions (room temperature and atmospheric pressure), catalysed by persistent and non‐persistent nitroxyl radicals in combination with transition metal salts, appears to be the most convenient of the numerous processes developed for these purposes. The thermochemistry, the kinetics, and the Hammett correlations have allowed us to establish, on a quantitative basis, the fundamental difference between the oxidation catalysed by persistent and non‐persistent nitroxyl catalysts. In the latter case, an interesting significant captodative effect is displayed for the first time for the oxidation of substituted benzyl alcohols; the importance of enthalpic and polar effects is emphasised. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Hetero‐Diels−Alder Approach to Phosphonothiashikimic Acid and New Thiaglycosides
Authors: Heras Montserrat , Gulea Mihaela , Masson Serge , Philouze Christian 
Published: December 2003

AbstractPhosphonodithioformates undergo hetero‐Diels−Alder cycloadditions with a variety of dienes. In some cases, Lewis acid catalysts were used to control the rate and selectivity of the reactions. Selective radical desulfanylation and subsequent dihydroxylation of the cycloadducts allowed the syntheses of new thiapyran derivatives and, in particular, a phosphono and thio analogue of shikimic acid. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Asymmetric Cyanosilylation of Ketones Catalyzed by Bifunctional Chiral N‐Oxide Titanium Complex Catalysts
Authors: Shen Yongcun , Feng Xiaoming , Li Yan , Zhang Guolin , Jiang Yaozhong 
Published: December 2003

AbstractA new bifunctional catalytic system based on chiral N‐oxide titanium complexes has been used for the asymmetric cyanosilylation of ketones. Screening of a variety of chiral N‐oxide metal complexes resulted in (1R,2S)‐1‐(2′‐pyridylmethyl)‐2‐(diphenylhydroxymethyl)pyrrolidine N‐oxide titanium complex, which gave O‐TMS cyanohydrins in good yields with enantiomeric excesses of up to 69 %. A catalytic cycle based on experimental phenomena and studies was proposed to explain the origin of the asymmetric induction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Comparison of Transition States During H‐Atom Abstraction of Monophenols and Catechol by Methyl Radical
Authors: Sun You‐Min , Liu Cheng‐Bu 
Published: December 2003

AbstractTo compare the transition states of para‐substituted phenols with that of catechol, we employed the B3LYP/6−311+G(d,p) method to calculate the energy profiles, the geometries, the spin density distributions, and other physico‐chemical parameters. A comparison between catechol and para‐substituted phenols indicates that their transition state geometries for hydrogen atom abstraction are similar. Substituent effects on the transition states of o‐substituted phenols may differ from those of p‐substituted ones. The calculated value of Ea for catechol is much lower than that of phenol, which arises mainly from the electron‐donating property of the ortho‐hydroxyl group. Although, the intramolecular hydrogen bond (IHB) effect on Ea is small, the IHB effect on the transition state geometry is fairly strong. According to the regression equation of the relative O−H bond dissociation enthalpy (BDE) versus values of Ea for p‐substituted monophenols, the relative O−H BDE of catechol is −8.28 kcal mol−1, which is in agreement with the value obtained through a kinetic analysis (−7.2 kcal mol−1). The values of Ea are governed by resonance effects, which is similar to the observation found for the O−H BDEs. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Total Synthesis of Premithramycinone H and Related Anthrapyran Antibiotics
Authors: Krohn Karsten , Vitz Jürgen 
Published: December 2003

AbstractTwo approaches are described for the preparation of 2‐(1′,3′‐dioxoalkyl)‐substituted 1‐hydroxyanthraquinones10a−dand20a−c, which were cyclized in a biomimetic‐type reaction to the anthra[1,2‐b]pyran skeletons11a−dand21a−cof the heydamycin‐ or pluramycin‐type antibiotics. Cleavage of the methyl ethers afforded the natural product premithramycinone H (2). The simple derivative11bshowed inhibition of the A431 cell line in µmolar concentrations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Efficient Access to Alanine Derivatives by 1,4‐Additions of Potassium Trifluoro(organo)borates
Authors: Navarre Laure , Darses Sylvain , Genet Jean‐Pierre 
Published: December 2003

AbstractPotassium trifluoro(organo)borates, highly stable and easily prepared organoboron derivatives, were able to react with a great variety of dehydroamino esters. This reaction, catalyzed by rhodium complexes, allowed the formation of alanine derivatives bearing a great variety of amino protecting groups in good to high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Aromatic Oligoamide Foldamers
Authors: Huc Ivan 
Published: December 2003

AbstractAromatic oligoamide foldamers possess a high potential for mimicking the secondary structures of biopolymers. These oligomers are efficiently designed, easy to synthesize, and allow one to reach a wide range of stable folded states. The aryl−amide bond rotation can be restricted through specific attractive and repulsive interactions between the amide and the other functional groups at the ortho position on the aryl moiety. The overall conformation of an oligomer results from the simple linear combination of the local conformational preferences at each amide bond. Thus, the curvature of the oligomeric strand may be tuned from strictly linear to highly bent, giving rise to helices of controllable diameter and extended linear conformations. Conformational rearrangements such as helical−linear strand transitions may be induced upon changing the local conformational preference of aryl−amide bonds. These oligomers also aggregate in various ways, such as stacks of discs, face‐to‐face hydrogen‐bonded linear dimers, or entwined double helices. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
An Improved Access to 4‐Trifluoromethyl‐2(1H)‐quinolinones: The “Watering Protocol”
Authors: Marull Marc , Lefebvre Olivier , Schlosser Manfred 
Published: December 2003

AbstractCondensation of anilines with ethyl 4,4,4‐trifluoroacetoacetate (7) to afford the corresponding 4,4,4‐trifluoro‐3‐oxobutaneanilides (10), precursors to 4‐(trifluoromethyl)‐2‐quinolinones (11), can be favored and the competing condensation to produce the ethyl 4,4,4‐trifluoro‐3‐(phenylimino)butanoate, the precursor to 2‐(trifluoromethyl)‐4‐quinolinones, avoided if water is occasionally added to the reaction mixture while ethanol is continuously removed by distillation. The anilides 10 also form selectively when 4,4,4‐trifluoroacetoacetyl chloride (6) is allowed to react with anilines. The cyclization of the anilides has to be accomplished under carefully controlled conditions. The resulting 4‐(trifluoromethyl)‐2‐quinolinones (11) can be converted into 4‐(trifluoromethyl)quinolines (13), 4‐(trifluoromethyl)‐2‐quinolinecarboxylic acids (14), and 2‐bromo‐4‐(trifluoromethyl)quinolines (12), the last of which may in turn be converted into 2‐bromo‐4‐(trifluoromethyl)‐3‐quinolinecarboxylic acids (15) and eventually 4‐trifluoromethyl‐3‐quinolinecarboxylic acids (16). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
High π‐Facial Selectivity Through Chelation of Magnesium Ions in the DMD Epoxidation of α,β‐Unsaturated Imides with Chiral Pyrrolidinone Auxiliaries
Authors: Adam Waldemar , Zhang Aimin 
Published: December 2003

AbstractHigh diastereoselectivity, but of the opposite sense, is observed in the epoxidation (DMD or mCPBA) of α,β‐unsaturated imides equipped with pyrrolidinone‐type chiral auxiliaries that bear either a hydroxymethyl or trityloxymethyl side chain. This unprecedented reversed π‐facial differentiation is promoted by chelation of a magnesium ion, which results in conformational control over the essential steric interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Stereochemical Aspects of Enantiopure and Racemic Organolithium Aggregates Li4Ar4 {Ar = C6H4[CH(Me)NMe2]‐2}
Authors: Kronenburg Claudia M. P. , Rijnberg Evelien , Jastrzebski Johann T. B. H. , Kooijman Huub , Spek Anthony L. , van Koten Gerard 
Published: December 2003

AbstractThe compounds (R)‐ and rac‐[1‐(dimethylamino)ethyl]benzene, (R)‐1 and rac‐1, respectively, react quantitatively with tBuLi in a 1:1 molar ratio in pentane to give the corresponding (R)‐ and rac‐[Li4{C6H4[CH(Me)NMe2]‐2}4], (R)‐2 and rac‐2, respectively. The same reaction with nBuLi afforded a 1:1:1 aggregate of nBuLi, 2, and 1 according to the results of quench experiments with H2O and D2O. The 1H, 13C, and 7Li NMR spectra, as well as the single‐crystal X‐ray structure, reveal that (R)‐2 has a unique self‐assembled tetranuclear structure of two diastereoisomeric dimeric units both in solution, in non‐coordinating hydrocarbon solvents, and in the solid state. Detailed information about rac‐2, which, in contrast to the high solubility of (R)‐2, is essentially insoluble in hydrocarbon solvents, was provided by 13C CP/MAS NMR spectra. We conclude that rac‐2 is a self‐assembled tetranuclear aggregate comprising a combination of two dimeric units, but in this case they are derived from the (R)‐ and (S)‐enantiomers, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Conjugated and Cross‐Conjugated π‐Extended Cycloproparenes with Dithiole and Cyclopentadiene Functionality
Authors: Halton Brian , Jones Carissa S. 
Published: December 2003

AbstractDithiole and cyclopentadiene rings have been introduced into functionalised cyclopropa[b]naphthalenes to provide highly coloured, conjugated and cross‐conjugated π‐extended derivatives that have varying stability. Cyclopentadienylidene‐containing cyclopropanaphthalene 18 and its dithiolylidene analogue 25 are prepared from bromophenylcyclopropanaphthalene 12, and the 1,1‐biscyclopentadienylidene 20 from dibromide 13. Use of dithiole‐containing ketones with 1,1‐bis(trimethylsilyl)cyclopropa[b]naphthalene 10 gives the π‐extended cycloproparenes 27 and 29 in Peterson olefinations that are more efficient than Wittig−Horner reactions of cyclopropanthraquinone 31 with dithiolate 24 to give the cross‐conjugated cycloproparenes 34 and 35. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cover Picture: Aromatic Oligoamide Foldamers (Eur. J. Org. Chem. 1/2004)
Authors: Huc Ivan 
Published: December 2003

AbstractThe cover picture shows a photograph of a helical origami, based on a modular ring designed by David Petty, surrounded by five examples of building blocks used in aromatic oligoamide foldamers. The background is an unfolded origami paper displaying the crease pattern that codes for a well‐defined folded shape. In the ancient Japanese art of paper folding, beautiful and complex yet predictable forms arise from a series a folding steps of a sheet of paper. Each step sets the relative orientation of the two sides of the fold. Similarly, the conformations of aromatic oligoamide foldamers are determined by interactions between consecutive units. In first approximation, the overall conformation is simply predicted as a linear combination of local conformational preferences. Details are discussed in the Microreview by I. Huc on p. 17 ff. We thank Professor Louis Cuccia for his inspiration and major contribution to this image.
Capillary electrophoresis of synthetic peptide standards varying in charge and hydrophobicity
Authors: Popa Traian V. , Mant Colin T. , Hodges Robert S. 
Published: December 2003

AbstractA mixture of eight structurally closely related synthetic peptides as capillary electrophoretic (CE) standards is introduced. The almost identical mass‐to‐charge ratio of the standards, coupled with their random‐coil (i.e., no secondary structure) nature, offer a potent analytical test for CE to separate peptides varying only subtly in hydrophobicity. Parameters varied to effect a separation included background electrolyte concentration, temperature, applied voltage in capillary zone electrophoresis (CZE in uncoated capillaries), as well as the introduction of hydrophobic mechanisms to the separation either through the use of micelles or C8‐coated capillaries. Our step‐by‐step approach culminated in an optimized combination of a CZE mechanism for separation of differently charged peptide groups (based on common mass‐to‐charge ratio) and an ion‐pairing mechanism (effecting a separation within each group of identically charged peptides), which we have termed ion‐interaction CZE or II‐CZE. The study clearly shows how the peptide standards allow an excellent assessment of the resolving power of CE.
Partial filling technique in capillary electrophoresis for the separation of phenolic isomers with sulfonatocalix[4]arene as a selector
Authors: Xu Hui , Yu Xiao‐Dong , Chen Hong‐Yuan 
Published: December 2003

Abstractp‐Sulfonatocalix[4]arene was used as a selector in capillary electrophoresis to separate phenolic positional isomers. To avoid the detection interference caused by the high UV absorption of calixarene, the partial filling technique was applied. The operation variables, including buffer, separation voltage, the concentration of the selector and the plug length of the selector zone, were systematically optimized. The detection limits of mass were in the range of 0.07–0.28 pg. Molecular modeling was used to explain the interaction between calixarene and phenolic isomers.
Chiral separation with ligand‐exchange micellar electrokinetic chromatography using a D‐penicillamine‐copper(II) ternary complex as chiral selector
Authors: Zheng Zhi‐Xia , Lin Jin‐Ming , Qu Feng , Hobo Toshiyuki 
Published: December 2003

AbstractD‐Penicillamine is demonstrated for the first time as a chiral ligand for the enantioseparation of dansyl amino acids based on ligand‐exchange micellar electrokinetic chromatography (LE‐MEKC). Copper(II) was used as the central ion in the ternary complex. The effect of surfactant on the resolution was significant. A concentration of 20 mM sodium dodecyl sulfate (SDS) was shown to be necessary for the separation. Other important parameters, such as the concentration ratio of D‐penicillamine (D‐PEN) to Cu2+, the kind of metal central ion, the type and pH value of buffer, were also investigated. N‐Acetyl‐D‐penicillamine and L‐valine (Val), with similar structure to D‐penicillamine, were applied as their copper(II) complexes as chiral selector and the chiral recognition mechanism is briefly discussed. Under optimum experimental conditions, i.e., 20 mM NH4OAc, pH 6.5, a 2:1 concentration ratio of D‐penicillamine to Cu(II), 4 mM CuSO4 and 8 mM D‐penicillamine, the chiral separation of eight pairs of different dansyl amino acid enantiomers was accomplished with resolution ranging from 1.1 to 5.9. When L‐PEN was used instead of D‐PEN, reversal of the migration order was observed.
High‐throughput separation of DNA and proteins by three‐dimensional geometry gel electrophoresis: Feasibility studies
Authors: Ventzki Robert , Stegemann Josef 
Published: December 2003

AbstractWe report a novel separation method that is applicable to both DNA and protein samples, based on electrophoresis in a three‐dimensional (3‐D) geometry. In contrast to conventional electrophoresis, samples are applied in a two‐dimensional, planar array to one of the surfaces of a 3‐D geometry separation medium. Loading onto a plane results in a very high sample capacity. Sample migration and separation occur along the third spatial dimension, which is perpendicular to the loading plane. The key problem of electrophoresis in a 3‐D geometry separation setup is that temperature gradients are caused by Joule’s heat, affecting the electrical conductivity and viscosity of the separation medium. A means of achieving straight sample migration under these circumstances is to force heat flow through the separation medium parallel to the axis of sample migration. This can be done by dissipating the heat via the electrode sides of the gel and blocking any other heat transfer. The separation of DNA and proteins by this method has been tested using agarose gel electrophoresis, polyacrylamide gel electrophoresis, and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. Data were acquired off‐line by conventional staining methods as well as on‐line by detection of laser‐induced fluorescence. We describe how to excise samples from the separation medium for preparative purposes. Possible unique applications of this 3‐D geometry electrophoresis separation method are also discussed.
Perfusive flow and intraparticle distribution of a neutral analyte in capillary electrochromatography
Authors: Tallarek Ulrich , Pačes Martin , Rapp Erdmann 
Published: December 2003

AbstractThe relevance and magnitude of an electroosmotic perfusion mechanism in electrochromatography is analyzed. To systemize our studies we first considered the transport of an electroneutral and nonadsorbing tracer. Based on the refractive index matching in a microfluidic setup containing fixed spherical porous particles, we conducted a quantitative analysis in real time of the spatio‐temporal distribution of fluorescent tracer molecules during their uptake by (and a release from) single particles using confocal laser scanning microscopy. Even under conditions of a significant electrical double layer overlap the intraparticle electroosmotic flow produces due to its unidirectional nature and in striking contrast to the symmetric (spherical) distributions typical for purely diffusive transport strongly asymmetric concentration profiles inside spherical particles as the locally charged pore liquid begins to respond to the externally applied electrical field. The profiles retain an axisymmetric nature, i.e., rotational symmetry with respect to the field direction. Results of our measurements could be successfully interpreted and further analyzed by a compact mathematical model. Intraparticle Peclet numbers of up to 150 have been realized and found to significantly enhance the mass transport on particle scale towards the convection‐dominated regime when compared to a conventional (diffusion‐limited) kinetics.
Capillary zone electrophoresis with a dynamic double coating for analysis of carbohydrate‐deficient transferrin in human serum: Impact of resolution between disialo‐ and trisialotransferrin on reference limits
Authors: Lanz Christian , Thormann Wolfgang 
Published: December 2003

AbstractCapillary electrophoresis with a dynamic double coating formed by charged polymeric reagents represents a very effective tool for the separation of iron‐saturated transferrin (Tf) isoforms and thus the determination of carbohydrate‐deficient transferrin (CDT) in human serum. The resolution between di‐ and trisialo‐Tf is dependent on the applied voltage and capillary temperature. With a 50 μm inside diameter (ID) capillary of about 60 cm total length mounted into the P/ACE MDQ, 28 kV and 40°C, the resolution of the two Tf isoforms is shown to be between 1.0 and 1.4, whereas with reduced voltage and/or temperature, increased resolution at the expense of elongated run times is observed. Best data with complete resolution (Rs ≥ 1.4) are obtained at 20 kV and 30°C. For the determination of CDT in serum, incomplete separation of di‐ and trisialo‐Tf is demonstrated to have an impact on the reference limits. Analysis of the sera of 54 healthy individuals with no or moderate alcohol consumption and using valley‐to‐valley peak integration, the upper (lower) reference limits for CDT in relation to total Tf at the two power levels are 1.33 (0.52) and 1.57 (0.81)%, respectively, representing intervals that are significantly different (P < 0.001). Furthermore, the reference intervals are shown to be strongly dependent on the peak integration approach used. Valley‐to‐valley peak integration should only be employed for conditions with complete resolution between disialo‐ and trisialo‐Tf.