bluuebunny/crossref_metadata_2025_split huggingface dataset:
Superposition of tectono-thermal episodes in the southern Cantabrian Zone (foreland thrust and fold belt of the Iberian Variscides, NW Spain)
Authors: Aller Jesus , Valín María Luz , García-López Susana , Brime Covadonga , Bastida Fernando 
Published: January 2006

Abstract
The combined use of the illite “crystallinity” Kübler index (KI) and the conodont colour alteration index (CAI) has revealed the existence of three thermal episodes in an area affected by thin-skin tectonics, close to the internal zones of the Variscan orogen in NW Spain. In the southernmost part of the study area, the first episode gave rise to a regional syntectonic Variscan metamorphism. The associated deformation involves the development of a slaty cleavage, which is mainly recognized in Precambrian rocks. Towards the foreland, the syntectonic metamorphism disappears and only an incipient burial metamorphism, giving rise to anchizonal conditions in the basal part of the thrust units, is observed.
Another metamorphic episode occurred close to the Carboniferous-Permian boundary in an extensional tectonic regime. This metamorphism is restricted to the northern part of the study area, where it reached anchizonal or epizonal conditions. It is associated with a subhorizontal or moderately north-dipping cleavage and can be considered as a late-Variscan episode.
The last thermal episode occurred during the Permian. It was produced by heat flow due to hydrothermal fluids, whose migration was favoured by faults. The effects of this episode are irregularly distributed, and they are apparent in the unconformable Stephanian rocks in which anchizonal or epizonal conditions were reached. It is interpreted as a post-Variscan episode.
The Carboniferous Baralacha La basaltic dykes (Upper Lahul, Ladakh) : remnants of an early rifting event along the Indian northern plate
Authors: Chauvet François , Lapierre Henriette , Bosch Delphine , Demant Alain , Bussy François , Vannay Jean-Claude , Mascle Georges H. , Brunet Pierre , Cotten Joseph , Keller Francine 
Published: January 2006

Abstract
The Lower Carboniferous Baralacha La basaltic dykes were emplaced along transtensional faults. The basalts exhibit tholeiitic and alkaline affinities. The tholeiites are TiO2-poor, moderately enriched in light rare earth (LREE), and display Nb and Ta negative and Th positive anomalies. The alkali basalts, compared to the tholeiites, have higher TiO2, rare earth and highly incompatible trace element contents and greater LREE enrichments. The Nd and Pb isotope compositions of the Baralacha La basalts suggest that they derive from the partial melting of an enriched OIB mantle source, characterized by a HIMU component, and contaminated by the lower continental crust. The Baralacha La dyke swarm represent the remnants of an early rifting event on the northern Indian passive margin.
Intermolecular Forces in the Self‐Assembly of Peptide Amphiphile Nanofibers
Authors: Stendahl J. C. , Rao M. S. , Guler M. O. , Stupp S. I. 
Published: January 2006

AbstractPeptide amphiphile molecules (PAs) developed in our laboratory self‐assemble from aqueous media into three‐dimensional networks of bioactive nanofibers. Multiple non‐covalent interactions promote assembly of the supramolecular nanofibers and ultimately determine the bulk physical properties of the macroscopic gels. In this study, we use oscillatory rheology, Fourier‐transform infrared spectroscopy, and circular‐dichroism spectroscopy to better understand the assembly mechanism of a typical PA molecule known as PA‐1. Self‐assembly of PA‐1 is triggered by counterion screening and stabilized by van der Waals and hydrophobic forces, ionic bridging, and coordination and hydrogen bonding. The concentration, electronic structure, and hydration of counterions significantly influence self‐assembly and gel mechanical properties.
Synthesis of Polymer Bound Azabis(oxazoline) Ligands and their Application in Asymmetric Cyclopropanations
Authors: Werner Heiko , Herrerías Clara I. , Glos Michael , Gissibl Anja , Fraile Jose M. , Pérez Ignacio , Mayoral Jose A. , Reiser Oliver 
Published: January 2006

AbstractAza(bisoxazoline) ligands were attached to various polymeric supports and the resulting immobilized ligands were evaluated in copper(I)‐catalyzed asymmetric cyclopropanations. The efficiency of these transformations depends greatly on the polymeric support, on the protocol being applied for the immobilization of the ligands, and on the preparation of the catalysts.
Functional Resins as Hydrophilic Supports for Nanoclustered Pd(0) and Pd(0)‐Au(0) Catalysts Designed for the Direct Synthesis of Hydrogen Peroxide
Authors: Burato Claudio , Centomo Paolo , Rizzoli Maurizio , Biffis Andrea , Campestrini Sandro , Corain Benedetto 
Published: January 2006

AbstractThe commercial macroreticular cation exchanger resin Lewatit K2621/H+ and two gel‐type resins bearing SO3H and SMe functionalities are used to produce two acidic Pd(0)/resin(H+) and one non‐acidic Pd(0)‐Au(0)/resin catalysts that are tested in the direct synthesis of H2O2 in methanol/water (2.5 : 1) at −10 °C and moderate H2 and O2 pressures. Molar yields in H2O2 after 1.5 hours, range from 12.9% [Pd(0)‐Au(0)/resin] to 46% [Pd(0)/K2621/H+].
Mild Peroxidative Oxidation of Cyclohexane Catalyzed by Mono‐, Di‐, Tri‐, Tetra‐ and Polynuclear Copper Triethanolamine Complexes
Authors: Kirillov Alexander M. , Kopylovich Maximilian N. , Kirillova Marina V. , Karabach Evgeny Yu. , Haukka Matti , da Silva M. Fátima C. Guedes , Pombeiro Armando J. L. 
Published: January 2006

AbstractThe mono‐, di‐, tri‐, tetra‐ and polynuclear copper(II) triethanolamine (H3tea) complexes [Cu(H2tea)(N3)] (1), [Cu2(H2tea)2(XC6H4COO)2]⋅2 H2O (X=4‐H2a, 4‐CH32b, 3‐Cl2c), [Cu3(H2tea)2(4‐OC6H4COO)2(H2O)]⋅4H2O (3), [O⊂Cu4(tea)4(BOH)4][BF4]2(4) and [Cu2(H2tea)2{μ‐C6H4(COO)2‐1,4}n]⋅2n H2O (5), respectively, are highly active and selective catalysts or catalyst precursors for the peroxidative oxidation of cyclohexane, in acetonitrile, to a cyclohexanol and cyclohexanone mixture, by aqueous hydrogen peroxide in acidic medium (liquid biphasic catalysis) at room temperature and atmospheric pressure. The effects on the catalytic activity of various factors, e.g., the relative amounts of cyclohexane, oxidant, catalyst, solvent and nitric acid, reaction time, catalyst recycling and impact of both carbon‐ and oxygen‐centred radical traps (supporting mainly radical mechanisms) were investigated and allowed us to achieve yields and TONs up toca.39% and 380, respectively, corresponding to the most active copper systems so far reported for the oxidation of cyclohexane under mild conditions. The catalysts can be reused for recycling and, at least complex4maintains almost the same level of activity even after five reaction cycles. The preparation of the new complexes1, 2band2cby self‐assembly at room temperature, and their full characterization by IR spectroscopy, FAB‐MS+, elemental and X‐ray diffraction structural (for1and2c) analyses are also reported.
Solvent‐Free Chelation‐Assisted Catalytic CC Bond Cleavage of Unstrained Ketone by Rhodium(I) Complexes under Microwave Irradiation
Authors: Ahn Jeong‐Ae , Chang Duck‐Ho , Park Young Jun , Yon Ye Rim , Loupy André , Jun Chul‐Ho 
Published: January 2006

AbstractA highly efficient CC bond cleavage of unstrained aliphatic ketones bearing β‐hydrogens with olefins was achieved using a chelation‐assisted catalytic system consisting of (Ph3P)3RhCl and 2‐amino‐3‐picoline by microwave irradiation under solvent‐free conditions. The addition of cyclohexylamine catalyst accelerated the reaction rate dramatically under microwave irradiation compared with the classical heating method.
Novel Chiral Sulphonato‐Salen‐Manganese(III)‐Pillared Hydrotalcite Catalysts for the Asymmetric Epoxidation of Styrenes and Cyclic Alkenes
Authors: Bhattacharjee Samiran , Anderson James A. 
Published: January 2006

AbstractA novel chiral sulphonato‐salen‐manganese (III) complex has been prepared and intercalated into a Zn‐Al layered‐double hydroxide (LDH) structure. The resulting catalyst was found to be highly active and enantioselective in the epoxidation of various styrenes and cyclic alkenes when using a combination of pivalaldehyde and molecular oxygen at atmospheric pressure and room temperature. At 94% conversion, 1‐methyl‐1‐cyclohexene could be converted to epoxide with 68% ee and 90% selectivity with a turnover frequency (TOF) of 234 h−1, whereas 4‐methylstyrene was converted with 62% ee and 70% selectivity with a TOF of 327 h−1. In the case of styrenes and cyclic alkenes, TOF decreased as follows: α‐methylstyrene>4‐methylstyrene>styrene and 1‐methyl‐1‐cyclohexene>1‐phenyl‐1‐cyclohexene>cyclohexene. The catalyst could be recycled without detectable loss of efficiency.
Chiral Chromium(III) Porphyrins as Highly Enantioselective Catalysts for Hetero‐Diels–Alder Reactions Between Aldehydes and Dienes
Authors: Berkessel Albrecht , Ertürk Erkan , Laporte Cécile 
Published: January 2006

AbstractStarting from enantiomerically pure 5,10,15,20‐tetrakis[(1S,4R,5R,8S)‐1,2,3,4,5,6,7,8‐octahydro‐1,4 : 5,8‐dimethanoanthracene‐9‐yl]porphyrin, treatment with CrCl2 and subsequent air oxidation afforded the corresponding Cr(III) complex, with chloride as counterion, in 96% yield. Anion exchange with AgBF4 gave the corresponding tetrafluoroborate. These hitherto unknown chiral chromium porphyrins are efficient and highly enantioselective catalysts for the hetero‐Diels–Alder reaction of aliphatic, aromatic, and heteroaromatic aldehydes with dienes of varying electron density. In the case of 1‐methoxy‐3‐(trimethylsilyloxy)butadiene (“Danishefsky's diene”), enantiomeric excesses >90% were achieved in a number of cases, with furfural affording the highest ee (97%). Metal‐coordinating aldehydes such as pyridine‐2‐carbaldehyde do not inactivate the Cr(III) porphyrin catalyst. The cycloaddition of less electron‐rich dienes (such as 1‐methoxybutadiene) is effected as well, affording diastereoselectivities up to >99 : 1, and enantiomeric excesses >80%.
Lipase‐Involved Strategy to the Enantiomers of 4‐Benzyl‐β‐Lactam as a Key Intermediate in the Preparation of β‐Phenylalanine Derivatives
Authors: Li Xiang‐Guo , Kanerva Liisa T. 
Published: January 2006

AbstractA simple chemoenzymatic method for the preparation of the enantiomers of 4‐benzyl‐β‐lactam (4‐benzylazetidin‐2‐one) from allylbenzene has been described. The enantiomers of this key intermediate have been used to produce the corresponding enantiomers of β‐phenylalanine and N‐Boc‐protected β‐phenylalanine amide through the simple cleavage of the lactam ring by acid‐catalyzed hydrolysis and by ammonolysis, respectively. Burkholderia cepacia lipase‐catalyzed kinetic double resolution techniques were responsible for achieving enantiopurity in the products. This was performed through the acylation of N‐hydroxymethylated β‐lactam followed by the butanolysis of the obtained (S)‐ester. Direct lipase‐catalyzed cleavage of the β‐lactam ring has also been studied.
A General and Efficient Method for the Preparation of β‐Enamino Ketones and Esters Catalyzed by Indium Tribromide
Authors: Zhang Zhan‐Hui , Yin Liang , Wang Yong‐Mei 
Published: January 2006

AbstractA variety of β‐enamino ketones and esters have been synthesized in high to exellent yields by reacting β‐dicarbonyl compounds with amines in the presence of a catalytic amount of indium tribromide. The reaction proceeds smoothly at room temperature in a short reaction time under solvent‐free conditions.
Remarkable Anion and Cation Effects on Stille Reactions in Functionalised Ionic Liquids
Authors: Chiappe Cinzia , Pieraccini Daniela , Zhao Dongbin , Fei Zhaofu , Dyson Paul J. 
Published: January 2006

AbstractTask‐specific ionic liquids bearing nitrile functional groups attached to the cation and nitrogen‐donor‐containing anions strongly affect the efficiency of the Stille cross‐coupling, influencing the nature of the catalyst and its stability. The relative strengths of the coordinating power of the cations and anions are varied and compared, and under certain conditions nanoparticles are observed.
Filtration‐Free Recyclable Catalytic Asymmetric Dihydroxylation Using a Ligand Immobilized on Magnetic Mesocellular Mesoporous Silica
Authors: Lee Daewon , Lee Jinwoo , Lee Honggeun , Jin Sunmi , Hyeon Taeghwan , Kim B. Moon 
Published: January 2006

AbstractA new magnetic mesocellular mesoporous silica support featuring a 3D open‐pore structure has been developed for highly efficient, filtration‐free recycling of chiral ligands for catalytic asymmetric dihydroxylation. Reactions using the ligand immobilized on this magnetic silica system exhibited almost the same reactivity and enantioselectivity as those obtained in the homogeneous reaction. Magnetically recovered ligand could be recycled eight times with good to excellent conservation of reaction rates and enantioselectivities.
Insights into the “isolation” of the Basques: mtDNA lineages from the historical site of Aldaieta (6th–7th centuries AD)
Authors: Alzualde Ainhoa , Izagirre Neskuts , Alonso Santos , Alonso Antonio , Albarrán Cristina , Azkarate Agustin , de la Rúa Concepción 
Published: January 2006

AbstractWe analyzed the hypervariable region I (HVR‐I) sequence variability of the mitochondrial DNA (mtDNA) of individuals buried at Aldaieta (6th–7th centuries AD) in order to find out more about the biosocial implications of this cemetery. The results, fully authenticated by means of diverse criteria (analysis of duplicates, replication in an independent laboratory, quantification of target DNA, and sequencing and cloning of polymerase chain reaction products), suggest that Aldaieta largely consists of autochthonous individuals who shared common funereal customs with the late Ancient North Pyrenean cemeteries of Western Europe (the Reihengräberfelder), a cultural influence possibly accompanied by a certain genetic flow. Furthermore, the distribution of mtDNA lineages in the cemetery highlighted the existence of a significant number of family relationships, supporting the belief that it was a stable settlement and not a group that had haphazardly settled in the area. Finally, this paper stresses the importance of ancient DNA data for reconstructing the biological history of human populations, rendering it possible to verify certain hypotheses based solely on current population data. The presence at Aldaieta of an mtDNA lineage originating in Northwest Africa testifies to the existence of contact between the Iberian Peninsula and Northwest Africa prior to the Moorish occupation. Both this latter discovery and the high frequency of haplogroup J at the Aldaieta cemetery raise questions about the generally accepted belief that, since ancient times, the influence of other human groups has been very scarce in the Basque Country. Am J Phys Anthropol, 2006. © 2006 Wiley‐Liss, Inc.
Polymers based on phenyl methacrylate: Synthesis via atom transfer radical polymerization, characterization, monomer reactivity ratios, and thermal stabilities
Authors: Demirelli Kadir , Kaya Esin , Coşkun Mehmet 
Published: January 2006

AbstractThe atom transfer radical copolymerization of phenyl methacrylate (PMA) with methyl methacrylate (MMA) was performed in bulk at 110°C in the presence of ethyl 2‐bromoacetate, cuprous bromide (CuBr), and 2,2′‐bipyridine. Also, free‐radical copolymerization of PMA with MMA was carried out in the presence of 2,2′‐azobisisobutyronitrile in 1,4‐dioxane solvent at 60°C. The copolymers were characterized by IR, 1H NMR, and 13C NMR techniques. The compositions of the copolymers were determined from the 1H NMR spectra. The in situ addition of ethylmethacrylate to a macroinitiator—poly(phenyl methacrylate)[Mn = 10,560, Mw/Mn = 1,68]—afforded an AB‐type block copolymer. The molecular weight and molecular weight distribution were obtained using gel permeation chromatography (GPC). The polydispersities for the living copolymer (48 mol % PPMA units) and the free‐radical copolymer (42 mol % PPMA) were 1.43 and 2.40, respectively. For the two copolymerization systems, the monomer reactivity ratios were obtained by using both Kelen–Tüdös and Fineman–Ross equations. The initial decomposition temperatures of the resultant copolymers decreased with increasing mole fraction of PMA, which indicate that heat resistance of copolymer improved by decreasing the PMA units. Blends of poly(PMA) and poly(MMA) obtained via ATRP method were prepared by casting films from dichloromethane solution. The blends were characterized by differential thermal analysis or differential scanning calorimetry and thermogravimetry. The results were comparable with each other. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3344–3354, 2006
Different effects of tri(acryloyloxyethyl) phosphate on the thermal degradation of photopolymerized epoxy acrylate and polyurethane acrylate films
Authors: Liang Hongbo , Huang Zhanguang , Shi Wenfang 
Published: January 2006

AbstractTri(acryloyloxyethyl) phosphate (TAEP) was blended in different ratios with epoxy acrylate EB600 and polyurethane acrylate EB270 to obtain a series of UV curable flame retardant resins. The thermal degradation mechanisms of their cured films in air were studied by thermogravimetric analysis, in situ Fourier‐transform infrared spectroscopy, and direct pyrolysis/mass spectrometry measurements. The results showed that the phosphate group in TAEP first degraded to form poly(phosphoric acid) before the degradation of EB600. Then, the formed poly(phosphoric acid) effectively promoted the conversion of EB600 to form char, which prevented the sample from further burning. However, urethane group in EB270 degraded simultaneously with phosphate group in TAEP, leading to not effectively increase the conversion of EB270 to char during the thermal degradation. It was thus found that the addition of TAEP more effectively improved the thermal stability, flame retardance, and the char yield during combustion of EB600 than those of EB270. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3130–3137, 2006
Molecular morphology of petaloid bases of PET bottles: A small‐angle X‐ray scattering study
Authors: Hanley Tracey , Sutton David , Cookson David , Kosior Edward , Knott Robert 
Published: January 2006

AbstractSmall‐angle X‐ray scattering (SAXS) studies were undertaken to explore possible morphological explanations for poor mechanical strength in the petaloid bases of poly(ethylene terephthalate) (PET) bottles. The bottles were manufactured using a two‐stage injection stretch blow molding process. Splitting of PET bottle bases under load is both inconvenient and expensive. In this study, SAXS data were collected with a 100 μm square X‐ray beam to establish the molecular morphology as a function of position across the base topology. An amorphous region was identified in the base center (i.e., close to the injection gate of the preform) with biaxially orientated, semicrystalline regions in the feet and valleys of the bottle bases. For bottles that had split under load, the transition between these two regions displayed uniaxial orientation that would lead to reduced mechanical strength in the circumferential direction. Reasons for this effect are explored. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3328–3335, 2006
Towards improving wet‐adhesion in a metal oxide‐polymer coating system
Authors: Devasahayam Sheila 
Published: January 2006

AbstractAn investigation using a variable radius roll adhesion test (VaRRAT) revealed an irreversible increase in the wet‐adhesion in a metal–oxide–polymer system, under specific experimental conditions. This observation is further confirmed by the Tg measurements and the ATR‐FTIR studies. The increase in wet‐adhesion is attributed to late H2O‐catalyzed curing of the previously partially cured polymers (epoxy ring opening), as well as the formation of nanocomposite layer within the epoxy primer matrix, because of precipitation of the nanocrystals including zinc ammine complexes formed as a result of dissolution of the zinc/aluminum alloy as well as the metal oxide pigments by the amine crosslinker. High activation energy of ∼100 kJ mol−1 indicated a chemical process to be responsible for the adhesion gain. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3318–3327, 2006
Water‐insoluble polymers containing amine, sulfonic acid, and carboxylic acid groups: Synthesis, characterization, and metal‐ion‐retention properties
Authors: Rivas Bernabé L. , Villegas Sandra , Ruf Beatriz 
Published: January 2006

AbstractCrosslinked poly(acryloylmorpholine) and its copolymers poly(acryloyl morpholine‐co‐acrylic acid) and poly(acryloylmorpholine‐co‐2‐acrylamide‐2‐methyl‐1‐propane sulfonic acid) were synthesized by radical polymerization. The resins were completely insoluble in water and were characterized with Fourier transform infrared spectroscopy and thermal analysis. The metal ions Ag(I), Cu(II), Cd(II), Hg(II), Zn(II), Pb(II), Al(III), and Cr(III) were investigated under competitive and noncompetitive conditions by a batch equilibrium procedure. The resin‐metal‐ion equilibrium was achieved before 5 min. The recovery of the resin was investigated at 20°C with different concentrations of HNO3 and HClO4. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3266–3274, 2006
Homogeneous and heterogeneous grafting of 4‐vinylpyridine onto chitosan
Authors: Elkholy Said S. , Khalil Khalid D. , Elsabee Maher Z. 
Published: January 2006

AbstractModification of chitosan by grafting with 4‐vinylpyridine (VP) was carried out both in homogeneous and heterogeneous phases, using potassium persulfate (K2S2O8) and sodium bisulfite (NaHSO3) as redox initiators. The effect of monomer concentration, initiator concentration and redox ratio, time and temperature on the extent of grafting (G%), homopolymer formation, and the efficiency of grafting were studied. Values of grafting percentages up to 96% were reached in heterogeneous conditions and up to 130% in homogeneous conditions (in 5% acetic acid). The grafting was confirmed by FTIR and 1H NMR spectroscopy. The grafted samples were characterized by scanning electron microscopy, X‐ray diffraction, and thermogravimetric analysis. The crystallinity of the used chitosan was not affected by grafting, it even increased slightly. Dye uptake of the grafted samples towards the different types of dyes (acidic and basic) was investigated and was found to improve profoundly over the native chitosan with a higher uptake for the acidic dye. The grafted samples showed an increased swelling in water, which increased further upon quaternization of the graft copolymers. The extent of swelling is higher in acidic and basic media more than in neutral pH. The grafted copolymers are soluble with difficulty in warm acetic acid solution. The quaternized graft copolymer was found to be soluble in water. The biological activity of the quaternized graft copolymers (G = 130 and 80%) was investigated and was found to have an inhibition effect on both the Azotobacter fungus and the bacterium Fusarium oxysporium. The effect on the micro organisms is proportional to the amount of VP in the graft copolymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3308–3317, 2006
Study on the spin probe‐added polymeric dense membranes by 13C solid‐state nuclear magnetic resonance spectroscopy
Authors: Rana D. , Matsuura T. , Khulbe K. C. , Feng C. 
Published: January 2006

AbstractThis article is a duplicate of an article previously published in the Journal of Applied Polymer Science, Vol. 99, No. 6, March 15, 2006, pp. 3062‐3069 http://doi.wiley.com/10.1002/app.22908.
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