bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards a comprehensive distal andesitic tephrostratigraphic framework for New Zealand based on eruptions from Egmont volcano
Authors: Shane Phil 
Published: January 2005

AbstractThe chronology and glass composition of 43 andesitic tephra layers in palaeolake sediments in northern New Zealand provide the basis for a fine‐resolution tephrostratigraphy of the interval 10–70 cal. ka. Their ages are constrained by 14 interbedded, (mostly) well‐dated rhyolitic tephra layers. The andesitic tephra have the potential to subdivide time intervals (1–5 kyr) bracketed by well known rhyolitic layers, including periods of rapid climate change such as the last glacial–interglacial transition and the Younger Dryas. The source of the distal andesitic tephra is identified as Egmont volcano (some 270 km S‐SW) on the basis of glass shard composition. The tephra contain high‐K2O (3–6 wt%) andesitic‐dacitic (SiO2 = 60–73 wt%) glass, with commonly heterogeneous shard populations (2–10 wt% SiO2). Within stratigraphic intervals of < 10 kyr, individual tephra layers can be distinguished on the basis of their SiO2 and K2O contents, and variability in these contents can also be a distinguishing characteristic. The tephra record greatly extends the dated pyroclastic and geochemical record of Egmont volcano, and demonstrates that the volcano has frequently produced widely dispersed tephra over the last 70 kyr at a generally constant rate. Copyright © 2005 John Wiley & Sons, Ltd.
U‐series dating of the Late Pleistocene mammalian fauna from Wood Quarry (Steetley), Nottinghamshire, UK
Authors: Pike A. W. G. , Eggins S. , Grün R. , Hedges R. E. M. , Jacobi R. M. 
Published: January 2005

AbstractWe present the U‐series dating of bones from Wood Quarry (‘Steetley Quarry Cave’) using the diffusion–adsorption model to account for uranium uptake. The results give a weighted mean date of 66.8 ± 3.0 kyr, placing this assemblage within or just before Marine Oxygen Isotope Stage 4. The fauna is thought to correlate with the Banwell Bone Cave mammal assemblage‐zone of the Early Devensian in Britain. Our results support the idea that this assemblage‐zone immediately precedes the assemblage represented nearby at Pin Hole in Creswell Crags which is contemporary with the Mid‐Devensian and correlates with MIS 3. Our dates, and dates for the Banwell Bone Cave mammal assemblage‐zone from Stump Cross Cavern and evidence from other sites may indicate a longevity for this fauna. Copyright © 2005 John Wiley & Sons, Ltd.
Investigation of Fungal Deterioration of Synthetic Paint Binders Using Vibrational Spectroscopic Techniques
Authors: Cappitelli Francesca , Vicini Silvia , Piaggio Paolo , Abbruscato Pamela , Princi Elisabetta , Casadevall Arturo , Nosanchuk Joshua D. , Zanardini Elisabetta 
Published: January 2005

AbstractSummary: The deterioration of synthetic polymers caused by biological process is usually evaluated by visual inspection and measuring physical effects. In contrast to this approach, we have applied vibrational spectroscopies to study the biodegradation of the synthetic resins. 29 synthetic resins used as paint binding media, including acrylic, alkyd and poly(vinyl acetate) polymers, were examined for potential susceptibility to fungal degradation using the standard method ASTM G21‐96(2002). In addition, the degraded resins were analysed by Raman spectroscopy, FT‐IR and FT‐IR photoacoustic spectroscopy. Almost all the acrylic resins studied proved to be resistant to microbial attack, while all alkyd resins and some poly(vinyl acetates) turned out to be biodegradable. Within a few days of inoculation Aspergillus niger was the most copious fungus on the biodegraded resins. A comparison of the IR and Raman spectra of control and biodegraded resins did not show any differences, but photoacoustic spectroscopy revealed additional bands for the fungal‐degraded resins, consistent with the presence of fungal‐derived substances. The additional bands in the photoacoustic spectra were due to the presence of Aspergillus niger and melanin, a fungal pigment. Since IR photoacoustic spectroscopy can be also a suitable technique for the chemical characterisation of binding media, the same spectroscopic analysis can be employed to both characterise the material and obtain evidence for fungal colonization.Microbial growth on Sobral 1241ML (alkyd resin) after 28 d (growth rating 4) compared with the non‐inoculated resin.imageMicrobial growth on Sobral 1241ML (alkyd resin) after 28 d (growth rating 4) compared with the non‐inoculated resin.
Characterization of Methyl Methacrylate Grafting onto Preirradiated Biodegradable Lignocellulose Fiber by γ‐Radiation
Authors: Khan Ferdous 
Published: January 2005

AbstractSummary: Gamma‐radiation‐induced graft copolymerization of methyl methacrylate onto natural lignocellulose (jute) fiber was carried out by the preirradiation method in an aqueous medium by using octylphenoxy‐polyethoxyethanol as an emulsifier. The different factors that influenced the graft copolymer reaction process were investigated. In the case of radiation‐dose‐dependent grafting, samples irradiated in the presence of air produced up to 73% graft weight compared to 53% obtained in the case of irradiation in a nitrogen environment. By assuming Arrhenius reaction kinetics, the activation energy (Ea) of the grafting reaction process was evaluated for different reaction temperatures. Moreover, the graft copolymer reaction was controlled by incorporating a homopolymer‐inhibiting agent and three different chain‐transfer agents in the reaction medium. The mechanical and thermal properties of jute fiber ‘as received’ and jute‐graft‐poly(methyl methacrylate) were also investigated. The results showed that the percentage of grafting with jute fiber has a significant effect on the properties. The kinetic parameters were evaluated from TGA thermograms by using Broido's method in the temperature range 240–350 °C. Scanning electron micrographs show that the structural changes on the surface of jute fibers were induced by graft copolymerization of methyl methacrylate monomer. Fiber‐fiber surface friction was measured in terms of the average maximum load and the kinetic friction.SEM of jute‐graft‐poly(methyl methacrylate).imageSEM of jute‐graft‐poly(methyl methacrylate).
Cover Picture: Macromol. Biosci. 12/2004
Authors: Yang Jing , Jia Lin , Yin Lingzhi , Yu Jianyong , Shi Zhen , Fang Qiang , Cao Amin 
Published: January 2005

Cover: The Figure schematically shows the synthesis of novel aluminum metal complexes bearing chiral Salen ligand and mono‐/difunctional water‐soluble poly(ethylene glycol) MPEG/PEG. The complexes are used as synthetic templates for the preparation of amphiphilic MPEG‐b‐PCL/PVL, PCL/PVL‐b‐PEG‐b‐PCL/PVL di‐/triblock copolymers with well‐defined macromolecular architectures. The amphiphilic biodegradable copolymers provide new possibilities for preparing uniform biodegradable micelles and/or external‐stimulus sensitive biodegradable gel networks for applications as biomimetic and functional biomaterials.Further details can be found in the Full Paper by J. Yang, L. Jia, L. Yin, J. Yu, Z. Shi, Q. Fang, and A. Cao* on page 1092.
A Mathematical Model for Photopolymerization From a Stationary Laser Light Source
Authors: Perry Michael F. , Young Gerald W. 
Published: January 2005

AbstractSummary: A mathematical model of photopolymerization is presented for a stationary laser. Termination by radical combination and radical trapping is considered. Using simplifying assumptions, we derive analytical equations for the concentration of photoinitiator and monomer in the system. With these equations, we show that the light intensity and the initial amount of photoinitiator highly influence the polymerization process and determine the shape of the polymer that is formed. We also provide an analytic expression to determine the amount of polymer formed during dark reactions.Percent conversion of monomer as a function of time at z = 0 and r = 0 (Data from Table 1).imagePercent conversion of monomer as a function of time at z = 0 and r = 0 (Data from Table 1).
Selective effect of repetitive hand movements on intracortical excitability
Authors: Renner Caroline I. E. , Schubert Margot , Hummelsheim Horst 
Published: January 2005

AbstractRepetitive training of isolated movements induces local reorganization of the motor cortex. To investigate the effect of repetitive movements on intracortical inhibition and facilitation shortly after the movements, we performed paired‐pulse transcranial magnetic stimulation in 12 healthy subjects by using interstimulus intervals of 2 and 8 ms, respectively. Motor evoked potentials (MEPs) were recorded simultaneously from the extensor carpi radialis (ECR) and the flexor carpi ulnaris muscle (FCU) following paired stimuli at rest or 1 s after repetitive (every 6 s) active or passive wrist extensions and compared with MEPs produced by single stimuli at rest. The active movements produced significantly larger MEPs in the ECR but not the FCU muscle. Passive movements had no effect. Intracortical facilitation increased significantly after movements in the ECR only. Intracortical inhibition, however, did not change significantly after repetitive movements in either muscle. These findings support the notion that intracortical inhibition and facilitation may be controlled independently. Further, these data suggest that shortly after repetitive movements the excitability of the primary motor cortex representing the agonist muscle is increased by interaction with intracortical facilitatory circuits rather than by inactivating inhibitory circuits. Muscle Nerve, 2005
Radiation‐induced conduction block: Resolution following anticoagulant therapy
Authors: Soto Oscar 
Published: January 2005

AbstractNeurophysiologic studies documented proximal conduction blocks in a patient harboring a delayed radiation‐induced brachial plexopathy. Since anticoagulants have been reported to be beneficial in radiation‐induced neuropathies, the patient was started on acenocumarol. After 3 months of treatment there was significant improvement of clinical deficits, which correlated with resolution of conduction blocks. This observation suggests that ischemic nerve injury leading to disruption of the conduction properties of motor axons contributes to the pathogenesis of delayed radiation‐induced peripheral nerve injuries. Muscle Nerve, 2005
Thermo‐solvatochromism of zwitterionic probes in aqueous aliphatic alcohols and in aqueous 2‐alkoxyethanols: relevance to the enthalpies of activation of chemical reactions
Authors: Tada Erika B. , Silva Priscilla L. , Tavares Clarissa , El Seoud Omar A. 
Published: January 2005

AbstractThe thermo‐solvatochromic behavior of 2,6‐dichloro‐4‐(2,4,6‐triphenylpyridinium‐1‐yl)phenolate (WB), 1‐methylquinolinium‐8‐olate (QB) and 4‐[2‐(1‐methylpyridinium‐4‐yl)ethenyl]phenolate (MC) was investigated in binary mixtures of water (W) and 2‐alkoxyethanols (ROEtOH) in the temperature ranges from 10 to 60°C (2‐ethoxyethanol and 2‐n‐propoxyethanol) and 10 to 40°C (2‐n‐butoxyethanol). Thermo‐solvatochromic data were treated according to a model that is based on the presence in bulk solution of three solvents, W, ROEtOH and a 1:1 H‐bonded species, ROEtOH–W. Solvation by ROEtOH–W is favored over solvation by either of the two precursor solvents. The present data, and those recently published on thermo‐solvatochromism of the same probes in five alcohols (methanol, ethanol, 1‐propanol, 2‐propanol and 2‐methyl‐2‐propanol) and one ROEtOH (2‐methoxyethanol), were submitted to regression analysis. The results indicate that solvation is more sensitive to solute–solvent hydrophobic interactions than H‐bonding between the probe phenoxy oxygen and the hydroxyl group of the H‐bond donating solvent (HBD). Temperature increase results in gradual desolvation of the probes, due to the concomitant decrease of the structure of all components of the binary solvent mixture. For pure solvents, the temperature‐induced desolvation depends on the structure of the probe (order: WB>MC>QB) and the HBD solvent (order: 2‐ethoxyethanols>aliphatic alcohols, for the same alkyl group; organic solvent>water). The probe solvatochromic response is due to the electronic transition zwitterion→di‐radical; it serves as a model for reactions that are associated with a large polarity difference between the reagents and activated complexes. For WB, for ΔT = 50°C, the desolvation energies range from 2.1 to 3.7 kcal mol−1. The contribution of temperature‐induced desolvation to the activation enthalpies of these reactions is, therefore, important. Copyright © 2005 John Wiley & Sons, Ltd.
Development of an improved synthetic route to an AB phenylquinoxaline monomer
Authors: Baek Jong‐Beom , Harris Frank W. 
Published: January 2005

AbstractThe primary objective of this research was the development of an efficient synthetic route for a previously prepared self‐polymerizable PPQ monomer mixture, 2‐(4‐hydroxyphenyl)‐3‐phenyl‐6‐fluoroquinoxaline and 3‐(4‐hydroxyphenyl)‐2‐phenyl‐6‐fluoroquinoxaline. Thus, the intermediate, 4‐hydroxybenzil, was synthesized in good yield, starting from phenol with phenylacetyl chloride, followed by oxidation. The other intermediate, 4‐fluoro‐1,2‐phenylenediamine, was also less costly synthesized, starting from 2,4‐difluoronitrobenzene with ammonium hydroxide, followed by reduction, giving excellent yield. The overall monomer yield was superior to previous reports. Another research objective involved preparation of various monomer mixtures that could be synthesized even less costly, and attempts on polymerization could generate the same structure of PPQ from an original monomer mixture. Thus, the monomer mixture that had switched functional groups from the original one, 2‐(4‐fluorophenyl)‐3‐phenyl‐6‐hydroxyquinoxaline and 3‐(4‐fluorophenyl)‐2‐phenyl‐6‐hydroxyquinoxaline, was prepared. Various monomers with different functional groups attached on the 6‐position of the quinoxaline ring, such as chloro‐ and nitro‐substituted monomers instead of fluoro‐substituted ones, were also prepared. Several attempts to build up high molecular weights were not successful. In the case of the switched monomer mixture, weaker nucleophility and less activation on the fluorine atom were to be the reason in the switched monomer. In the cases of chloro‐ and nitro‐substituted monomers, poorer leaving power and side reactions were to be the reasons. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 801–814, 2005
Single electron transfer–degenerative chain transfer mediated living radical polymerization (SET–DTLRP) of vinyl chloride initiated with methylene iodide and catalyzed by sodium dithionite
Authors: Percec Virgil , Popov Anatoliy V. , Ramirez‐Castillo Ernesto , Coelho Jorge F. J. 
Published: January 2005

AbstractSingle electron transfer–degenerative chain transfer mediated living radical polymerization (SET–DTLRP) of vinyl chloride (VC) initiated with methylene iodide (CH2I2) and catalyzed by sodium dithionite (Na2S2O4) in water at 35 °C produces a telechelic poly(vinyl chloride) (LRP–PVC) with two different active chain ends:ICH2(CH2CHCl)n‐1CH2CHClI, and 2.0 functionality. The reactivity and initiator efficiency of CH2I2in SET–DTLRP of VC was lower than those of iodoform. A possible mechanism for the CH2I2‐initiated SET–DTLRP of VC was suggested. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 773–778, 2005
Phase transfer catalyzed single electron transfer–degenerative chain transfer mediated living radical polymerization (PTC‐SET–DTLRP) of vinyl chloride catalyzed by sodium dithionite and initiated with iodoform in water at 43 °C
Authors: Percec Virgil , Popov Anatoliy V. , Ramirez‐Castillo Ernesto , Coelho Jorge F. J. , Hinojosa‐Falcon Luis A. 
Published: January 2005

AbstractTo accelerate the living radical polymerization (LRP) of vinyl chloride (VC) in water the phase transfer catalyzed single electron transfer–degenerative chain transfer mediated living radical polymerization (SET–DTLRP) of VC mediated by sodium dithionite (Na2S2O4) was investigated. The fastest polymerization reaction that still produces thermally stable poly(vinyl chloride) (PVC) takes place at 43 °C with the ratio [PTC]0/[Na2S2O4]0= 0.0075/1. Cetyltrimethylammonium bromide (nC16H33(CH3)3N+Br−, CetMe3NBr) was the phase‐transfer catalyst (PTC) of choice. Under these conditions the first, fast stage of SET–DTLRP of VC was accomplished within 7–8 h when the initial ratio monomer/initiator [VC]0/[CHI3]0was 800. The number‐average molecular weight (Mn) of the resulting PVC was in good agreement with the theoretical molecular weight (Mth). When the [VC]0/[CHI3]0ratio was 4800, the fast step of the reaction was accomplished within 17 h, to produce 72% monomer conversion. A deviation of theMnfrom theMthwas observed in this case. Possible mechanistic explanations for this deviation as well as for the phase transfer catalyzed SET–DTLRP of VC were suggested. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 779–788, 2005
Synthesis, isolation, and characterization of polytitanasiloxanes and zirconasiloxanes by the hydrolytic cocondensation of tetraethoxysilane and titanium or zirconium tetraisopropoxide
Authors: Gunji Takahiro , Yokogawa Masanari , Hongo Masahiro , Abe Yoshimoto 
Published: January 2005

AbstractPolytitanasiloxanes and polyzirconasiloxanes were synthesized through the hydrolytic cocondensation of tetraethoxysilane (TEOS) and tetraisopropoxytitanium (TPT) or tetraisopropoxyzirconium (TPZ) 2‐propanol adduct (process A) and through the reaction of partially hydrolyzed TEOS with TPT or TPZ (process B) and were isolated as acetylacetonato derivatives stable against self‐condensation. In both processes, acetylacetone was added to provide acetylacetonato derivatives of polytitanasiloxanes and polyzirconasiloxanes. In process A, titanium‐ or zirconium‐rich polymetallasiloxanes were formed during the initial stage of the process, whereas the molar ratio of silicon to titanium or zirconium was gradually increased up to almost unity with an increasing reaction time. In process B, the molar ratio gradually increased below and above unity as the molar ratio of water to TEOS increased. When the acetylacetonato derivatives of polymetallasiloxanes were subjected to heat treatment, the titania or zirconia component was crystallized. The crystallization temperature increased as the silica content and the molar ratio of water to TEOS increased, and this demonstrated that the crystallization was dependent on the sequence in the main chain of the polymetallasiloxanes. The 29Si NMR spectra of the polymetallasiloxanes led to the idea that the backbone metallasiloxane linkages consisted of random and block sequences for processes A and B, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 763–772, 2005
Synthesis and characterization of single‐wall‐carbon‐nanotube‐doped emeraldine salt and base polyaniline nanocomposites
Authors: Do Nascimento Gustavo M. , Corio Paola , Novickis Richard W. , Temperini Marcia L. A. , Dresselhaus Mildred S. 
Published: January 2005

AbstractNanocomposites of polyaniline (PANI) and single‐wall carbon nanotubes (SWNTs) were prepared and characterized via resonance Raman and electronic absorption spectroscopy (ultraviolet–visible/near‐infrared). The chemical synthesis of PANI was performed in the presence of SWNTs in concentrations ranging from 10 to 50 wt % (SWNT/PANI). The obtained materials were hydrophilic, homogeneous composite compounds. The chemical interaction between PANI (in the conducting emeraldine salt form and in the insulating emeraldine base form) and metallic and semiconducting nanotubes was investigated. The emeraldine salt form of the polymer was significantly stabilized in the composite in comparison with plain PANI. A selective electronic interaction process between PANI and metallic SWNTs was found. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 815–822, 2005
FTIR spectroscopic investigation of thermal effects in semi‐syndiotactic polypropylene
Authors: Sevegney Michael S. , Kannan Rangaramanujam M. , Siedle Allen R. , Percha Pamela A. 
Published: January 2005

AbstractThe temperature‐dependent behavior of individual components within metallocene‐catalyzed semisyndiotactic polypropylenes (semi‐sPP) with a wide range of stereoregular content (26 to 96% rr) is studied using Fourier transform infrared (FTIR) spectroscopy and temperature‐modulated differential scanning calorimetry (DSC). Changes in sensitive, high‐resolution absorbance spectra are observed as melt‐slow‐cooled thin films are subjected to stepwise temperature increases. In general, spectral bands previously identified as being sensitive to ordered structures (e.g., conformed chains, crystal morphs) appear to follow overall trends of shifting to lower wavenumbers (energies), broadening, and decreasing in peak area intensity as temperature increases. Peaks that appear due to “splitting” (observed in more stereoregular materials) show a trend toward coalescence as temperature increases; this corresponds to a gradual loss of chain conformational order. Gauche‐gauche‐trans‐trans (ggtt)n helical and all‐trans (tttt)n planar zigzag‐conformed chains that participate in the crystalline‐amorphous interfacial region (“mesophase”) appear to be more stable (i.e., they do not lose their conformational order as easily) with increasing temperature in materials with a greater degree of syndiotacticity. Moreover, IR data correspond well with modulated DSC endotherms located near 50 °C and 70 °C. At each transition temperature—thought to represent, respectively, a thermally driven chain conformation from planar zigzags to helices, and a dynamic disorder of helices marked by rapid gauche ↔ trans isomerization—the IR absorbance ratio, A978/A963, which represents the relative population of helical chains, undergoes an accelerated decrease. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 439–461, 2005
Morphology and mechanical properties of binary triblock copolymer blends
Authors: Lach Ralf , Weidisch Roland , Knoll Konrad 
Published: January 2005

AbstractThe influence of the morphology on the mechanical properties of binary styrene–butadiene (SB) triblock copolymer blends of a thermoplastic block copolymer and a thermoplastic elastomer (TPE) with different molecular architectures was studied with bulk samples prepared from toluene. Both block copolymers contained SB random copolymer middle blocks, that is, the block sequence S–SB–S. The two miscible triblock copolymers were combined to create a TPE with increased tensile strength without a change in their elasticity. The changes in the equilibrium morphology of the miscible triblock copolymer blends as a function of the TPE content (lamellae, bicontinuous morphology, hexagonal cylinders, and worms) resulted in a novel morphology–property correlation: (1) the strain at break and Young's modulus of blends with about 20 wt % TPE were larger than those of the pure thermoplastic triblock copolymer; (2) at the transition from bicontinuous structures to hexagonal structures (∼35 wt % TPE), a change in the mechanical properties from thermoplastic to elastomeric was observed; and (3) in the full range of wormlike and hexagonal morphology (60–100 wt % TPE), elastomeric properties were observed, the strength greatly increasing and high‐strength elastomers resulting. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 429–438, 2005