bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carpetlike dense‐layer formation in a polyelectrolyte brush at the air/water interface
Authors: Mouri Emiko , Matsumoto Kozo , Matsuoka Hideki 
Published: July 2003

AbstractA carpetlike dense‐layer formation between a hydrophobic layer and a polyelectrolyte brush layer has been found in the monolayers of an ionic amphiphilic diblock copolymer, poly(1,1‐diethylsilacyclobutane)m‐block‐poly(methacrylic acid)n, on a water surface by an X‐ray reflectivity technique. By detailed analysis, we have found that the hydrophilic layer under the water is not a simple layer but is divided into two layers, that is, a carpetlike dense methacrylic acid (MAA) layer near the hydrophobic layer and a polyelectrolyte brush layer. We have also confirmed that a well‐established polyelectrolyte brush is formed only for them:n= 43:81 polymer monolayer: Form:n= 40:10 andm:n= 45:60 polymer monolayers, only a dense MAA layer is formed. This dense‐layer formation should be the origin of the interesting hydrophobic‐layer thickness variation previously reported; The hydrophobic‐layer thickness takes a minimum as a function of the hydrophilic chain length at any surface pressure studied. An overview of the data for three samples with different chain lengths (m:n= 40:10, 45:60, or 43:81) has shown that the thickness of this dense layer is 10–20 Å and is independent of the surface pressure and polymerization degree of poly(methacrylic acid) (PMAA) in the range studied. This dense‐layer formation is explained by the reasonable speculation that contact with PMAA is thermodynamically more stable than direct contact with water for the diethylsilacyclobutane (Et2SB) layer on water. In this sense, the dense layer acts like a carpet for the hydrophobic Et2SB layer, and a 10–20‐Å thickness could be a critical value for the carpet. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1921–1928, 2003
Effects of polymeric dispersants and surfactants on the dispersing stability and high‐speed‐jetting properties of aqueous‐pigment‐based ink‐jet inks
Authors: Chang Chi‐Jung , Chang Shinn‐Jen , Tsou Susan , Chen Shou‐I , Wu Feng‐Mei , Hsu Mei‐Wen 
Published: July 2003

AbstractGood jetting performance and pigment‐dispersing stability are necessary for pigment‐based ink‐jet inks. This study investigates how the chemical structures of the polymeric dispersants affect the pigment‐dispersing stability and jetting performance of ink‐jet inks. A series of polymeric dispersants containing styrene (hydrophobic unit) and acrylic acid (hydrophilic unit) with different ratios have been synthesized and used to disperse different pigments. Because 3000–12,000 ink drops can be expelled from the nozzle of a thermal bubble‐type ink‐jet printer within 1 s, the jetting behavior is related to the rheology variation of a dilute solution under a high shear. An in situ drop formation system has been used to study the high‐shear‐rate rheology (dynamic surface tension and dynamic viscosity) of a solution with a viscosity lower than 3 cps, which no commercial rheometer can measure. Excellent ink‐jet inks can only be produced by the combination of pigments, dispersants, and surfactants with appropriate hydrophilicity. Moreover, the correlation of the pigment surface properties, the chemical structures of the polymeric dispersants, and ink formulation is discussed. The effects of the surfactants and firing conditions on the jetting behavior of the ink‐jet ink are also examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1909–1920, 2003
Impact of average free‐volume element size on transport in stereoisomers of polynorbornene. II. Impact of temperature on solubility
Authors: Wilks Broderick R. , Rezac Mary E. 
Published: July 2003

AbstractThis article evaluates the influence of temperature on the sorption of gases in two isomers of polynorbornene. The subject polymers were stereoisomers with nearly identical bulk density and total free volume. Because of differences in the mobility of the polymer backbone, the isomers packed differently resulting in differences in the average free‐volume element size within the matrix. The influence of these differences on free‐volume element size was characterized by the heat of sorption of gases in the matrix. The most pronounced differences were observed in the isosteric heats of sorption of condensable carbon dioxide and methane in the polymer isomers. This analysis suggests that the relative space available for sorption into free‐volume elements is higher in the methyl II isomer relative to methyl III. These conclusions support the physical characterizations reported in Part I of this series suggesting that the methyl II isomer has larger average free‐volume elements but fewer of them than the methyl III isomer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1939–1946, 2003
Preparation and characterization of some unusually transparent poly(dimethylsiloxane) nanocomposites
Authors: Rajan Guru S. , Sur Gil S. , Mark James E. , Schaefer Dale W. , Beaucage Gregory 
Published: July 2003

AbstractA technique was developed for preparing poly(dimethylsiloxane) nanocomposites having unusually high transparencies as quantitatively judged by ultraviolet–visible spectroscopy. The method was the in situ generation of silica particles by a two‐step sol–gel procedure in which the required water of hydrolysis was simply absorbed from the air, and the catalyst was generated in situ from a tin salt. Electron microscopy showed that the phase‐separated silica domains were very small (30–50 nm in diameter) and well dispersed, as expected from the transparency of the composites. Stress‐strain measurements in tension indicated that the particles provide very good reinforcement. Ultra‐small‐angle X‐ray scattering data showed that the domain morphology depends strongly on catalyst, but weakly on loading level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1897–1901, 2003
Benzonitriles: Survey of their importance and scaling of their vibrational frequencies
Authors: Alcolea Palafox M. , Rastogi V. K. , Mittal Lalit 
Published: July 2003

AbstractThis work provides a short survey of the studies carried out on benzonitrile and its derivatives, with special attention on a spectroscopic point of view. The importance and main applications of these molecules are also briefly indicated. For an accurate assignment of their vibrational spectra, the scaling procedures for the wave numbers are described. For this purpose, the performance of semiempirical, ab initio, and density functional methods, with different basis sets, is determined. A “resume” of the main scaling factors to be used in the calculated wave numbers is shown. The results obtained for several benzene derivatives, and in particular for four benzonitriles, are analyzed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 189–204, 2003
Phosphoryl group differentiating α‐amino acids from β‐ and γ‐amino acids in prebiotic peptide formation
Authors: Jiang Yang , Tan Bo , Chen Zhong‐Zhou , Liu Tong , Zhong Ru‐Gang , Li Yan‐Mei , Stewart David Jeremy , Zhao Yu‐Fen , Jiang Hua‐Liang 
Published: July 2003

AbstractIn recent years β‐amino acids have increased their importance enormously in defining secondary structures of β‐peptides. Interest in β‐amino acids raises the question: Why and how did nature choose α‐amino acids for the central role in life? In this article we present experimental results of MS and 31P NMR methods on the chemical behavior of N‐phosphorylated α‐alanine, β‐alanine, and γ‐amino butyric acid in different solvents. N‐Phosphoryl α‐alanine can self‐assemble to N‐phosphopeptides either in water or in organic solvents, while no assembly was observed for β‐ or γ‐amino acids. An intramolecular carboxylic–phosphoric mixed anhydride (IMCPA) is the key structure responsible for their chemical behaviors. Relative energies and solvent effects of three isomers of IMCPA derived from α‐alanine (2a–c), with five‐membered ring, and five isomers of IMCPA derived from β‐alanine (4a–e), with six‐membered ring, were calculated with density functional theory at the B3LYP/6‐31G** level. The lower relative energy (3.2 kcal/mol in water) of 2b and lower energy barrier for its formation (16.7 kcal/mol in water) are responsible for the peptide formation from N‐phosphoryl α‐alanine. Both experimental and theoretical studies indicate that the structural difference among α‐, β‐, and γ‐amino acids can be recognized by formation of IMCPA after N‐phosphorylation. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 232–241, 2003
Case for projectile kinetic energy gain in stopping power studies
Authors: Cabrera‐Trujillo R. , Sabin J. R. , Öhrn Y. , Deumens E. 
Published: July 2003

AbstractUnder certain collision conditions, a swift ion projectile colliding with a target will gain rather than lose kinetic energy, contrary to the standard conception of stopping power. In this work, we consider the conditions for such a collision such that the energy loss is negative, that is, that there will be projectile kinetic energy gain. In particular, for a target initially in the ground state we find that the projectile gains kinetic energy only when charge exchange and de‐excitation processes are involved. This occurs when the electron affinity of the projectile is larger than the ionization potential of the target. Consequences of this effect are analyzed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 215–221, 2003
Pyrenula luteopruinosa sp. nov. from Panama and notes on other members of the genus
Authors: Etayo Javiar , Aptroot André 
Published: July 2003

AbstractPyrenula luteopruinosa Etayo & Aptroot is described as new from lowland rainforest on the Pacific coast of Panama. The new name Pyrenula caraibica Aptroot & Etayo and the new combinations Pyrenula chilensis (Fée) Aptroot & F. Berger, Pyrenula cryptothelia (Müll. Arg.) Aptroot & Etayo and Pyrenula hibernica (Nyl.) Aptroot are proposed.
Determinant factors for the formation of the calcium oxalate minerals, weddellite and whewellite, on the surface of foliose lichens
Authors: Giordani Paolo , Modenesi Paolo , Tretiach Mauro 
Published: July 2003

AbstractThe factors influencing the predominance of one of the two mineral forms of calcium oxalate (CO), the monohydrated whewellite (COM) and the di-hydrated weddellite (COD), forming the pruina of the upper cortex of lichens, have been investigated through a simple, sensitive histochemical assay: toluidine blue O (TBO), a metachromatic staining test. The differential reactivity of 43 thalli of 17 pruinose foliose species, supplemented by X-ray diffraction analysis and observations with polarizing and scanning electron microscopy, suggests that the histochemical reactivity of hyphal walls and cementing substances of the upper cortex are related to the density of anionic charges. These factors are probably due to the occurrence of polyuronic acid substances that strongly affects the mineralization of CO. Di-hydrated wedellite is always associated with TBO metachromatic reactivity, and COM with orthochromatic reactivity. When the material has an ambiguous ortho/metachromatic reactivity, COD and COM may occur together. This study presents the first experimental evidence that in lichens CO biomineralization is at least partially biologically controlled.
A late Quaternary record of eolian silt deposition in a maar lake, St. Michael Island, western Alaska
Authors: Muhs Daniel R. , Ager Thomas A. , Been Josh , Bradbury J. Platt , Dean Walter E. 
Published: July 2003

AbstractRecent stratigraphic studies in central Alaska have yielded the unexpected finding that there is little evidence for full-glacial (late Wisconsin) loess deposition. Because the loess record of western Alaska is poorly exposed and not well known, we analyzed a core from Zagoskin Lake, a maar lake on St. Michael Island, to determine if a full-glacial eolian record could be found in that region. Particle size and geochemical data indicate that the mineral fraction of the lake sediments is not derived from the local basalt and is probably eolian. Silt deposition took place from at least the latter part of the mid-Wisconsin interstadial period through the Holocene, based on radiocarbon dating. Based on the locations of likely loess sources, eolian silt in western Alaska was probably deflated by northeasterly winds from glaciofluvial sediments. If last-glacial winds that deposited loess were indeed from the northeast, this reconstruction is in conflict with a model-derived reconstruction of paleowinds in Alaska. Mass accumulation rates in Zagoskin Lake were higher during the Pleistocene than during the Holocene. In addition, more eolian sediment is recorded in the lake sediments than as loess on the adjacent landscape. The thinner loess record on land may be due to the sparse, herb tundra vegetation that dominated the landscape in full-glacial time. Herb tundra would have been an inefficient loess trap compared to forest or even shrub tundra due to its low roughness height. The lack of abundant, full-glacial, eolian silt deposition in the loess stratigraphic record of central Alaska may be due, therefore, to a mimimal ability of the landscape to trap loess, rather than a lack of available eolian sediment.
The Eastern Beringian voleMicrotus deceitensis(Rodentia, Muridae, Arvicolinae) in Late Pliocene and Early Pleistocene faunas of Alaska and Yukon
Authors: Storer John E. 
Published: July 2003

AbstractThe fossil voleMicrotus deceitensisoccurs in Early Pleistocene deposits at Fort Selkirk, Yukon Territory, and Late Pliocene beds at the type locality, Cape Deceit, Alaska. Analyses of simple vs complex morphotypes in the cheek teeth, and of differentiation of tooth enamel, show that the Cape Deceit sample ofM. deceitensisis less derived, and thus appears to be older, than the Fort Selkirk sample. The fossiliferous deposits at Fort Selkirk are well constrained by fission-track and radiometric dates and are 1.5 to 1.7 myr. Sediments at Cape Deceit bear a normal magnetic polarity, are correlated with the Olduvai subchron, and probably are latest Pliocene.
The effect of capsular tightening on humeral head translations
Authors: Werner Clément M. L. , Nyffeler Richard W. , Jacob Hilaire A. C. , Gerber Christian 
Published: July 2003

AbstractIdiopathic or surgical tightening of the glenohumeral joint capsule may cause displacement of the humeral head relative to the glenoid fossa and favor the development of instability and/or osteoarthritis.In the present investigation the relative position of the humerus to the glenoid fossa was determined at the end of the ranges of eight different passive movements before and after selective capsular plication in eight cadaveric shoulders to study the effects of selective capsular plications on the kinematics of the shoulder.While the capsule was in its unaltered state, translation of the humeral head was 3.8 mm superiorly in abduction, 7.3 mm antero‐superiorly in flexion. In internal rotation in 0°, 45° and 90° of abduction the head moved 6.1, 8.0 and 12.0 mm antero‐inferiorly. In external rotation at 0° of abduction the translation was 0.9 mm antero‐inferiorly, at 45° and 90° of abduction it was 4.3 and 5.6 mm postero‐inferiorly, respectively.Plications of the anterior part of the capsule reproducibly and significantly either increased or decreased translations during flexion (up to 5.9 mm anteriorly and up to 3.8 mm inferiorly), external rotation (up to 2.9 mm posteriorly and 1 mm inferiorly) and internal rotation (from 5.5 mm posteriorly to 2 mm anteriorly and up to 2.2 mm superiorly). Posterior plications had only little effect on translations (mainly a decrease of anterior translation during flexion of 2.8 mm).Clinical relevance: The ‘obligate’ glenohumeral translations which occur towards the end of passive shoulder movements are altered in a reproducible fashion by tightening specific parts of the glenohumeral joint capsule, as often carried out in treatment of shoulder instability. These alterations of the kinematics of the glenohumeral joint may be relevant for the development of static subluxation and osteoarthitis as seen after too tight plication in the treatment of instability [Int. Orthop. (SICOT) 67‐B (1985) 709; J. Bone Joint Surg. Am. 72 (1990) 1193; J. Bone Joint Surg. Am. 66‐A (1984) 169; J. Bone Joint Surg. Am. 65 (1983) 456]. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
The pelagic life of the pectinid Pecten maximus—a review
Authors: Le Pennec M , Paugam A , Le Pennec G 
Published: July 2003

Abstract
Although marine bivalves go through a planktonic larval phase, knowledge of this phase is often poor because of the difficulty in identifying and monitoring the activity of these tiny organisms within the water mass. Some bivalves have been studied more than others, often because of their economic value. These species can serve as a model for improving our understanding of the circumstances of planktonic larval development, in particular by assessing its impact on recruitment. This review is aimed at summarizing the knowledge on the pelagic life of Pecten maximus acquired by research in France over the last 25 years. The comparison of these results with those obtained elsewhere for pectinid species, indicates certain characteristics that appear to be fairly common to all coastal infralittoral pectinids. Regardless of species, pelagic life of pectinids starts with the release of gametes, followed by fertilization and embryonic and larval stages until metamorphosis and recruitment to the benthic community. After consideration of the main characteristics of the pelagic stages and their sensitivity to certain environmental factors, a graphic synthesis is provided displaying their migratory behaviour and the possible consequences for recruitment.
Reconciling theoretical versus empirical target strengths of krill: effects of phase variability on the distorted-wave Born approximation
Authors: Demer David A. , Conti Stephane G. 
Published: July 2003

Abstract
A model was recently proposed to predict the target strengths (TS) of Antarctic krill, Euphausia superba, versus incidence angle (θ) (Deep Sea Res. II 45(7) (1998) 1273). Based on the distorted-wave Born approximation (DWBA), the model depends on the coherent summation of scattering from elements of a discretized-bent cylinder. It was empirically validated at 120 kHz near-broadside incidence (θ≈90°), but large discrepancies were observed at other angles away from the main lobe. As the side-lobe measurements were both higher than the model predictions and above the noise floor, the authors noted that the differences were not entirely due to noise. In this study, the accuracy of the DWBA model is further explored. Results indicate that phase variability in the scatter from elements of a discretized-bent cylinder (krill model) causes a dramatic flattening in the side-lobe regions of TS(θ), while negligibly affecting the main scattering lobe. These results are consistent with the krill TS measurements reported by McGehee et al. Thus, by accounting for phase variability in the solution of the DWBA model, a more accurate and thus practical tool is developed for predicting krill TS.
On estimating the age composition of the commercial catch of Northeast Arctic cod from a sample of clusters
Authors: Sondre Aanes , Pennington Michael 
Published: July 2003

Abstract
Assessment of Northeast Arctic cod is based on estimates of the commercial catch in numbers at age. The age structure of the catch is estimated by sampling fish from commercial fishing trips. Although it is commonly assumed that a sample of individuals is a random sample from the population, fish sampled from the same trip (i.e. from a “cluster” of fish) tend to be more similar in age than those in the total catch. For Northeast Arctic cod, the intracluster correlation for age is positive, and therefore the effective sample size is much smaller than the number of fish aged. Given the number of fish aged, the precision of the estimated age distribution is rather low, and the number of fish aged from each trip could be reduced from approximately 85 to 20 without a significant loss in precision.
Ichthyoplankton distribution and plankton production related to the shelf break front at the Avilés Canyon
Authors: González-Quirós R , Cabal J , Álvarez-Marqués F , Isla A 
Published: July 2003

Abstract
The overall objective of this study was to search for spatial differences in primary production and its transference towards larval fish related with the distribution of water masses at shelf break of the Avilés Canyon. High primary production and ichthyoplankton abundance were associated with a shelf break front at the Avilés Canyon. Egg distributions of Scomber scombrus, Sardina pilchardus and Trachurus trachurus, coupled with topography, the associated physical structure and phytoplankton productivity, suggested adaptive spawning strategies. The distribution of copepod stages, which are considered the trophic link between primary producers and fish larvae, was not related with the position of the front. Moreover, the egg production of two abundant species (Calanus helgolandicus and Acartia clausi) was not significantly related with phytoplankton abundance and productivity.
Age at maturation predicted from routine scale measurements in Norwegian spring-spawning herring (Clupea harengus) using discriminant and neural network analyses
Authors: Engelhard Georg H , Dieckmann Ulf , Godø Olav Rune 
Published: July 2003

Abstract
We evaluate two methods allowing the prediction of age at maturation from the widths of the annual growth layers in scales (or otoliths) in a case study on Norwegian spring-spawning herring. For this stock, scale measurements have been made routinely for many decades. We compare the performance in classifying age at maturation (at 3, 4,…,9 years) between conventional discriminant analysis (DA) and the new methodology of artificial neural networks (NN) trained by back-propagation against a ‘control’ of historical estimates of age at maturation obtained by visual examination of scales. Both methods show encouraging, and about equally high, classification success. The marginal differences in performance are in favour of DA, if the proportion of correctly classified cases is used as criterion (DA 68.0%, NN 66.6%), but in favour of NN if other criteria are used, including prediction error (error >1 year: DA 5.2%, NN 2.9%), and the average degree of under- or overestimation (underestimation 1.1% of mean with DA; overestimation 0.2% of mean with NN). Evidence is provided that both methods approach the a priori limits to maximal classification success, limits set by overlapping combinations of predictor variables between maturation groups. The methods allow studies on age at maturation in this stock over a very long timespan, including periods well before, during, and after its collapse to commercial extinction. Similar techniques might well be applicable to any other fish stock with long-term data on scale or otolith growth layers.