bluuebunny/crossref_metadata_2025_split huggingface dataset:
Substantial changes in central nervous system neurotransmitters and neuromodulators accompany phase change in the locust
Authors: Rogers Stephen M. , Matheson Thomas , Sasaki Ken , Kendrick Keith , Simpson Stephen J. , Burrows Malcolm 
Published: August 2004

SUMMARYDesert locusts (Schistocerca gregaria) can undergo a profound transformation between solitarious and gregarious forms, which involves widespread changes in behaviour, physiology and morphology. This phase change is triggered by the presence or absence of other locusts and occurs over a timescale ranging from hours, for some behaviours to change, to generations,for full morphological transformation. The neuro-hormonal mechanisms that drive and accompany phase change in either direction remain unknown. We have used high-performance liquid chromatography (HPLC) to compare amounts of 13 different potential neurotransmitters and/or neuromodulators in the central nervous systems of final instar locust nymphs undergoing phase transition and between long-term solitarious and gregarious adults. Long-term gregarious and solitarious locust nymphs differed in 11 of the 13 substances analysed: eight increased in both the brain and thoracic nerve cord (including glutamate,GABA, dopamine and serotonin), whereas three decreased (acetylcholine,tyramine and citrulline). Adult locusts of both extreme phases were similarly different. Isolating larval gregarious locusts led to rapid changes in seven chemicals equal to or even exceeding the differences seen between long-term solitarious and gregarious animals. Crowding larval solitarious locusts led to rapid changes in six chemicals towards gregarious values within the first 4 h(by which time gregarious behaviours are already being expressed), before returning to nearer long-term solitarious values 24 h later. Serotonin in the thoracic ganglia, however, did not follow this trend, but showed a ninefold increase after a 4 h period of crowding. After crowding solitarious nymphs for a whole larval stadium, the amounts of all chemicals, except octopamine, were similar to those of long-term gregarious locusts. Our data show that changes in levels of neuroactive substances are widespread in the central nervous system and reflect the time course of behavioural and physiological phase change.
Testing olfactory foraging strategies in an Antarctic seabird assemblage
Authors: Nevitt Gabrielle , Reid Keith , Trathan Phil 
Published: August 2004

SUMMARY
Procellariiform seabirds (petrels, albatrosses and shearwaters) forage over thousands of square kilometres for patchily distributed prey resources. While these birds are known for their large olfactory bulbs and excellent sense of smell, how they use odour cues to locate prey patches in the vast ocean is not well understood. Here, we investigate species-specific responses to 3-methyl pyrazine in a sub-Antarctic species assemblage near South Georgia Island(54°00 ′ S, 36°00 ′ W). Pyrazines are scented compounds found in macerated Antarctic krill (Euphausia superba), a primary prey item for many seabird species in this region. To examine behavioural attraction to this odour, we presented birds with either scented or`unscented' vegetable oil slicks at sea. As a positive control for our experiments, we also compared birds' responses to a general olfactory attractant, herring oil. Responses to pyrazine were both highly species specific and consistent with results from earlier studies investigating responses to crude krill extracts. For example, Cape petrels (Daption capense), giant petrels (Macronectes sp.) and white-chinned petrels (Procellaria aequinoctialis) were sighted at least 1.8–4 times as often at pyrazine-scented slicks than at control slicks. Black-browed albatrosses (Diomedea melanophris) were only sighted at pyrazine-scented slicks and never at control slicks. Wilson's storm-petrels(Oceanites oceanicus), black-bellied storm-petrels (Fregetta tropica), great shearwaters (Puffinus gravis) and prions(Pachyptila sp.) were sighted with equal frequency at control and pyrazine-scented slicks. As expected, responses to herring oil were more common. With the exception of great shearwaters (Puffinus gravis),each of these species was sighted up to five times as often at slicks scented with herring oil compared with control slicks. Together, the results support the hypothesis that Antarctic procellariiforms use species-specific foraging strategies that are inter-dependent and more complex than simply tracking prey by scent.
Dietary ecospace and the diversity of euprimates during the Early and Middle Eocene
Authors: Gilbert Christopher C. 
Published: August 2004

AbstractThis study examined adapoid and omomyoid euprimate dietary and body size diversity from the Eocene of North America and Europe. Estimates of body weights and shearing quotients calculated from lower molars were plotted on a coordinate graph as a representation of dietary niche space (dietary ecospace) occupied by extinct species. By computing the areas, average intertaxon distances, and average distances from the centroid of the resulting polygons, comparisons of Eocene euprimate dietary and body size diversity were made. Results indicate that euprimate dietary niche space expanded significantly in North America from the Early to Middle Eocene, and at all times during the Early and Middle Eocene, the niche space occupied by North American euprimates exceeded that of corresponding European euprimates. These results confirm that fossil euprimate diversity, as measured by diet and body size, significantly differed across biogeographic areas. There are many possible explanations as to why North American euprimates were significantly more diverse in terms of diet and body size than their European counterparts. The explanation advocated here as most responsible for the increased diversity during the Early and Middle Eocene relates to the existence and increased sampling of more ecologically diverse environments, such as basin margins in the western interior of North America. These diverse environments could have promoted biological processes that led to the generation of increased diversity in North America compared to the isolated island refugia of Western Europe during this time. Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.
Metallocene‐based functionalized polyolefins as compatibilizers in polyolefin nanocomposites
Authors: Motha Kshama , Hippi Ulla , Hakala Kimmo , Peltonen Maija , Ojanperä Vuokko , Löfgren Barbro , Seppälä Jukka 
Published: August 2004

AbstractThis article reports a study of some functionalized polyolefins evaluated as compatibilizers in polyethylene nanocomposites. The functionalized polymers were prepared by direct metallocene‐mediated copolymerizations of ethylene and a functional comonomer. The prepared nanocomposites were evaluated for mechanical and barrier property enhancement. A good combination of mechanical and barrier properties was obtained with the metallocene‐based functionalized polyethylene. The toughness–stiffness balance was better than or comparable to that achieved with conventional functionalized polymers such as maleic anhydride grafted polyethylene. The results also indicated that these metallocene‐based functionalized polyolefins, when used as compatibilizers, could have relatively higher molar masses and lower functionality than those of conventional post‐reactor‐modified compatibilizers, and so the drawbacks associated with the latter could be avoided. Their inherent properties could also further improve the final nanocomposite properties. This was attributed to the more homogeneous nature of metallocene‐catalyzed polymers in comparison with post‐reactor‐modified products. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1094–1100, 2004
Molecular weight dependency of refractive index increment of polystyrene determined by uniform oligomers
Authors: Itakura Masanao , Sato Keisuke , Lusenkova Marina A. , Matsuyama Shigetomo , Shimada Kayori , Saito Takeshi , Kinugasa Shinichi 
Published: August 2004

AbstractMolecular weight dependency of a specific UV absorption coefficient of polystyrene in solution was determined by supercritical fluid chromatography applied to equimolar and equimass mixtures of uniform polystyrenes whose degree of polymerization was n = 1 to 40. From the ratio between the response from a UV detector and that from a refractometer, we determined the refractive index increment dn/dc as a function of molecular weight for polystyrene in tetrahydrofuran at the wavelength λ = 633 nm. We found that dn/dc is well expressed as a linear function of the reciprocal of molecular weight for uniform polystyrenes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1101–1106, 2004
Characterization by Fourier transform infrared spectroscopy of polyethylene adipate/cholesteryl palmitate blends
Authors: Popescu Maria‐Cristina , Vasile Cornelia , Filip Daniela , Macocinschi Doina , Singurel Gh. 
Published: August 2004

AbstractFT‐IR spectroscopy has been employed to study compatibility, melting, and crystallization of the polyethylene adipate (PEA)/cholesteryl palmitate (CP) blends. The changes in FT‐IR spectra were followed by controlled rate of heating and cooling. The bands corresponding to the crystalline structure have been assigned. The accuracy of the transition temperature determination has been improved by fitting the curve of the integral absorbance dependence on temperature with a Boltzmann function. From dependence of the transition temperatures on the composition of the blend, it has been established that for each mixing ratio a certain mass fraction of CP should be dissolved in the PEA matrix. The PEA/CP blends behave as a phase‐separated system with partial miscibility. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1156–1163, 2004
Structural relaxation and morphology of the rubber–urethane composites
Authors: Danch Adam , Sułkowski Wieslaw W. , Moczyński Marek , Radon Agnieszka , Stelzer Franz , Jurga Stefan 
Published: August 2004

AbstractThe supermolecular structures and structural relaxation of the waste rubber–urethane composites are discussed on the basis of results of calorimetric measurements and mechanical spectroscopy. The results give a broader understanding of the relationship between processing history and morphology in the resultant engineering products. The effect of different kinds of urethane prepolymer on the thermomechanical properties of commercial composite products is presented. The idea of reaction between rubber granulate and urethane prepolymer is under consideration. The shear and tensile modes were applied to better explore relaxations that occur in rubber grains and in an interphase area created by the urethane agents. The rubber waste management problem was taken into account also. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1186–1193, 2004
Morphology and fracture behavior of intercalated epoxy/clay nanocomposites
Authors: Liu Tianxi , Tjiu Wuiwui Chauhari , Tong Yuejin , He Chaobin , Goh Sok Sing , Chung Tai‐Shung 
Published: August 2004

AbstractEpoxy/clay nanocomposites were prepared by swelling organoclay in an epoxy resin, diglycidyl ether of bisphenol A, followed by curing with an aromatic hardener, diethyltoluenediamine. A combination of X‐ray diffraction with transmission electron microscopy showed the coexistence of intercalated and exfoliated clay morphologies throughout the matrix. In addition, a microscopic and homogeneous dispersion of clay agglomerations, with sizes ranging from about 2 to 5 μm, was revealed by optical microscopy. Dynamic mechanical analysis indicated a steady increase in storage modulus and a gradual decrease in high glass‐transition temperature as the clay loading increased. The fracture toughness of the nanocomposites significantly increased with increasing clay concentration, suggesting a toughening effect from the clay particles. Scanning electron microscopy and optical microscopy observations of the epoxy/clay nanocomposites suggested that shear yielding of the matrix, crack deflection, voiding, and debonding of clay particles and epoxy matrix are among the operative toughening mechanisms observed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1236–1244, 2004
An investigation of fiber splitting of bicomponent meltblown/microfiber nonwovens by water treatment
Authors: Zhang Dong , Sun Christine (Qin) , Song Hua 
Published: August 2004

AbstractMeltblowing is a most versatile and cost‐effective process commercially available worldwide to produce microfiber nonwovens directly from thermoplastic resins. The new bicomponent (bico) meltblown technology opens a great possibility to make even finer microfibers by subsequently fiber splitting. Water‐dispersive Eastman AQ polymers were initially introduced to the meltblown process to make the mono‐ and bicomponent meltblown webs at Textiles and Nonwovens Development Center (TANDEC), University of Tennessee, Knoxville. The postwater treatment was performed on the fabrics, which resulted in the dispersive part (AQ polymer) being dispersed in water and only the other part remaining in the bico web. A process–structure–property study is provided toward the research reported in this article. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1218–1226, 2004
Benzene physical and chemical organogels: Effect of network scaffolding on the thermodynamic behavior of entrapped solvent molecules
Authors: Marković Nov , Ginić‐Marković Milena , Dutta Naba K. 
Published: August 2004

AbstractThis paper presents a thermodynamic investigation of the benzene physical and chemical organogels, using differential scanning calorimetry (DSC) and intends to draw an appropriate relationship between the gel network structure and the properties. Physical gels, formed by an aluminium soap of fatty acid, and chemical gels, created by in situ cross‐linking of a siloxane copolymer are investigated. The effects of the type and quantity of the gelators and their corresponding network mesh size distribution in the gels on crystallization, melting, and their kinetics are examined. It appears that the kinetics of crystallization of the entrapped solvent is significantly affected by the quality of the gel network scaffolding and can be treated successfully by the Avrami equation of crystallization. From the melting behavior of the entrapped solvent crystallites, quantitative information about the number of solvent molecules bound per molecule of the gelator has been extracted. DSC proves to be a reliable technique to evaluate the population distribution of solvent molecules trapped in the physical and chemical organogel network scaffolding. The state of the solvent may be treated as a probe to understand the structure of the gels. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1253–1264, 2004
Selective repartition of in situ generated silica produced during the evolution of an epoxide network from a homogeneous precursors mixture and effects on properties
Authors: Mascia Leno , Heath R J. , Ng Vincent S. Y. 
Published: August 2004

AbstractPhase separation of organic networks derived from mixtures of reactive monomers and/or oligomers can take place through the formation of IPNs or precipitation of particles. The latter systems are widely used as a means of increasing the fracture toughness of thermosetting resins, and particularly for products obtained from mixtures of epoxy resins and functionalized aliphatic oligomers. In the present work several mixtures comprised of difunctional epoxy resins, silane functionalized perfluoroether oligomers, prehydrolyzed tetraethoxysilane, and an aromatic amine hardener were examined in a variety of compositions and preparative procedures. The aims were to control the kinetics of phase separation and the repartition of the different components in the two phases, so that the silica domains could be preferentially located within the precipitated soft particles. It was found that the silane functionalization of the perfluoroether oligomer provided an effective mechanism for the localization of the siloxane networks within the precipitated particles. However, phase separation by the precipitation of particles would only take place for systems in which the perfluoroether oligomer could be reacted with an excess of epoxy resin prior to adding the alkoxysilane solution and the hardener. Moreover, it was difficult to achieve the total localization of the siloxane component into the perfluoroether network. The siloxane species remaining dissolved in the resin gave rise to severe embrittlement of the products through reactions with the epoxy chains. Using mixtures of suitably functionalized perfluoroether oligomers it was possible to produce the conditions by which the localization of the silica domains into the precipitated particles could be maximized. This has resulted also in the formation of graded interphase regions and to a global improvement in mechanical properties, manifested as a concomitant increase in modulus, strength, and toughness. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1279–1290, 2004
Synthesis and Molluscicidal Activity of 5‐oxo‐5,6,7,8‐Tetrahydro‐4H‐Chromene Derivatives
Authors: Abdelrazek Fathy M. , Metz Peter , Farrag Ebtehal K. 
Published: August 2004

AbstractFurfurylidenemalononitriles and thienylidenemalononitriles were treated with 1,3‐cyclohexanediones to afford 2‐amino‐4‐hetaryl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromene‐3‐carbonitrile derivatives. The molluscicidal activity of these compounds was investigated.
Stahlverbundkonstruktionen im Parkhausbau
Authors: Kurz Wolfgang 
Published: August 2004

AbstractDie Stahlverbundbauweise hat sich aus technischen und wirtschaftlichen Erwägungen zu einer Regelbauweise für offene Parkhäuser entwickelt. In diesem Beitrag werden die Randbedingungen und Besonderheiten der Ausführung von Stahlverbundparkhäusern erläutert. Gebräuchliche und bewährte Tragwerke und Deckensysteme werden beschrieben. Besonderheiten hinsichtlich der Dauerhaftigkeit der Konstruktionen werden erläutert.
Two‐dimensional magic angle spinning NMR investigation of naturally occurring chitins: Precise 1H and 13C resonance assignment of α‐ and β‐chitin
Authors: Kono Hiroyuki 
Published: August 2004

Abstract13C homonuclear through‐bond correlations of α‐ and β‐chitin were determined by using two‐dimensional (2D) INADEQUATE spectra of these allomorphs purified from crab shell and squid pen, respectively. The 2D 13C–13C correlation spectra where two directly bonded carbons share a common double‐quantum frequency (DQ) enabled us to precisely assign all 13C resonances of the chitin allomorphs for the first time. Following the complete 13C assignment, 1H chemical shifts of protons attached to each carbon nuclei were assigned by 2D frequency‐switched Lee–Goldberg (FSLG) 1H–13C heteronuclear correlation (HETCOR) spectra of the chitin allomorphs, recorded with a short mixing time (60 μs) to provide isotropic 1H–13C chemical shift correlations between bonded pairs proton and carbon nuclei. From the 13C and 1H chemical shifts of chitin allomorphs, all 2‐deoxy‐2‐acetamide‐D‐glucose (N‐acetyl‐D‐glucosamine) monomer units in each allomorph were revealed to be an identical 13C–13C backbone conformation and magnetically equivalent. In addition, it was strongly suggested that there are two different hydrogen‐bonding patterns at the hydroxyl groups of α‐chitin by comparing 1H chemical shifts at the C6 site of α‐chitin with those at the same site of β‐chitin. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Stimulation of methanol degradation in UASB reactors: In situ versus pre‐loading cobalt on anaerobic granular sludge
Authors: Zandvoort Marcel H. , Gieteling Jarno , Lettinga Gatze , Lens Piet N.L. 
Published: August 2004

AbstractThe effect of pre‐loading and in situ loading of cobalt onto a cobalt‐limited granular sludge on the performance of methanol fed bioreactors was investigated. One upflow anaerobic sludge bed (UASB) reactor was inoculated with cobalt pre‐loaded sludge (24h; 30°C; 1 mM CoCl2) and a second UASB with unloaded sludge. The UASB reactors (30°C; pH 7) were operated for 77 days at 8 h hydraulic retention time and organic loading rates ranging from 5 to 20 g COD · L reactor−1 · d−1. Cobalt pre‐loading clearly stimulated the methanogenic activity of the sludge with methanol as the substrate, e.g., after 30 days of reactor operation this activity was 5.8 times higher than that of the cobalt unloaded sludge. During the experiment, part of the cobalt leached from the pre‐loaded sludge, i.e., 54% of the cobalt content was lost during the 77 days of reactor operation. Sequential metal extraction showed that losses mainly occurred from the exchangeable and carbonate fraction and in the sludge remaining cobalt was mainly present in the organic/sulfide fraction of the sludge. In situ loading of cobalt in the unloaded UASB reactor on day 57 by adding 31 μM cobalt to the influent for a 24‐h period (16% of the cobalt present in the loaded sludge at day 11) resulted in a 4 time increase of the methanogenic activity of the sludge with methanol as the substrate at the end of the reactor experiment, while the accumulated amount of cobalt in the sludge only amounted to 6% of the cobalt accumulated in the loaded sludge (on day 11). This study showed that both pre‐loading sludge and in situ loading are adequate for achieving an increased reactor performance of methanol fed UASB reactors operating under cobalt limitation. However, the in situ dosing procedure needs substantially lower amounts of cobalt, while it also gives significantly smaller losses of cobalt with the effluent. © 2004 Wiley Periodicals, Inc.
Solid‐state fermentation: A continuous process for fungal tannase production
Authors: van de Lagemaat J. , Pyle D.L. 
Published: August 2004

AbstractTruly continuous solid‐state fermentations with operating times of 2–3 weeks were conducted in a prototype bioreactor for the production of fungal (Penicillium glabrum) tannase from a tannin‐containing model substrate. Substantial quantities of the enzyme were synthesized throughout the operating periods and (imperfect) steady‐state conditions seemed to be achieved soon after start‐up of the fermentations. This demonstrated for the first time the possibility of conducting solid‐state fermentations in the continuous mode and with a constant noninoculated feed. The operating variables and fermentation conditions in the bioreactor were sufficiently well predicted for the basic reinoculation concept to succeed. However, an incomplete understanding of the microbial mechanisms, the experimental system, and their interaction indicated the need for more research in this novel area of solid‐state fermentation. © 2004 Wiley Periodicals, Inc.
Development and validation of a high‐sensitivity liquid chromatography/tandem mass spectrometry (LC/MS/MS) method with chemical derivatization for the determination of ethinyl estradiol in human plasma
Authors: Shou Wilson Z. , Jiang Xiangyu , Naidong Weng 
Published: August 2004

AbstractAn ultra‐sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the analysis of oral contraceptive ethinyl estradiol (EE) was developed and validated over the curve range of 2.5–500 pg/mL using 1 mL of human plasma sample. Ethinyl estradiol and the internal standard, ethinyl estradiol tetra‐deuterated (EE‐d4), were extracted from the plasma matrix with methyl t‐butyl ether, derivatized with dansyl chloride and then back‐extracted into hexane. The hexane phase was evaporated to dryness, reconstituted and injected onto the LC/MS/MS system. The chromatographic separation was achieved on a Luna C18 column (50 × 2 mm, 5 µm) with an isocratic mobile phase of 20:80 (v/v) water:acetonitrile with 1% formic acid. The ofﬂine derivatization procedure introduced the easily ionizable tertiary amine function group to EE. This greatly improved analyte sensitivity in electrospray ionization and enabled us to achieve the desired lower limit of quantitation at 2.5 pg/mL. This high sensitivity method can be used for therapeutic drug monitoring or supporting bio‐equivalence and drug–drug interaction studies in human subjects. Copyright © 2004 John Wiley & Sons, Ltd.