bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multilayer Microwires: Tailoring Magnetic Behavior by Sputtering and Electroplating
Authors: Pirota K. , Hernández‐Vélez M. , Navas D. , Zhukov A. , Vázquez M. 
Published: March 2004

AbstractA novel technique for preparing multilayer microwires with controlled magnetic behavior has been developed. This technique involves combining sputtering and electroplating procedures to deposit (magnetic or non‐magnetic) metallic nano‐ and microlayers onto glass‐coated amorphous magnetic microwires. A suitable choice of magnetostrictive amorphous metallic nucleus, together with the specific stresses induced by the deposited layers, allows the tailoring of specific magnetic behavior. In this way, the preparation of multilayer microwires characterized either by square‐shaped hysteretic loops (typical of magnetically bistable microwires with longitudinal easy axes), or by nearly non‐hysteretic loops (for those microwires with a circumferential magnetization easy axes), can be achieved.
n‐Type Doping of Organic Thin Films Using Cationic Dyes
Authors: Werner A. , Li F. , Harada K. , Pfeiffer M. , Fritz T. , Leo K. , Machill S. 
Published: March 2004

AbstractWe present an approach to stable n‐type doping of organic matrices using organic dopants. In order to circumvent stability limitations inherent to strong organic donors, we produce the donor from a stable precursor compound in situ. As an example, the cationic dye pyronin B chloride is studied as a dopant in a 1,4,5,8‐naphthalene tetracarboxylic dianhydride (NTCDA) matrix. Conductivities of up to 1.9 × 10–4 S cm–1 are obtained for doped NTCDA, two orders of magnitude higher than the conductivity of NTCDA doped with bis(ethylenedithio)‐tetrathiafulvalene as investigated previously, and four orders of magnitude higher than nominally undoped NTCDA films. Field‐effect measurements are used to prove n‐type conduction and to study the doping effect further. The findings are interpreted using a model of transport in disordered solids using a recently published model. Combined FTIR, UV‐vis, and mass spectroscopy investigations suggest the formation of leuco pyronin B during sublimation of pyronin B chloride.
New perspectives in primate cognitive ecology
Authors: Garber Paul A. 
Published: March 2004

AbstractThe papers in this issue are from a symposium presented at the 71st Annual Meeting of the American Association of Physical Anthropologists held in Buffalo, New York, in April 2002. In the light of recent theoretical and methodological advances and debates in the study of cognition, this symposium addressed questions concerning primate cognitive ecology and decision‐making from a variety of perspectives. These include ontogenetic patterns of brain growth and learning, paleoecology and evolution, sensory adaptations, foraging strategies, tool‐using behavior, and concepts derived from the study of human cognition, such as schemata, planning, and rehearsal of activities. In this issue, data are presented on New World monkeys, Old World monkeys, apes, and humans. It is argued that the ability to make decisions based on the recognition that tertiary relationships in one context can be used to understand cause‐and‐effect relationships in an unrelated context may enable nonhuman primates to effectively reduce uncertainty and solve problems in changing social and ecological environments. Am. J. Primatol. 62:133–137, 2004. © 2004 Wiley‐Liss, Inc.
Brain growth, life history, and cognition in primate and human evolution
Authors: LEIGH S.R. 
Published: March 2004

AbstractThis study investigates brain size ontogeny in a sample of seven anthropoid primate species (including humans) in order to evaluate longstanding ideas about the relations between brain size, brain ontogeny, life history, and cognition. First, this analysis tests the hypothesis that primate brain growth patterns vary across species. Second, the relations between the duration of the brain growth period and the duration of the preadult period are evaluated. Brain growth data, derived from a number of sources, are analyzed through parametric and nonparametric regressions. The results indicate that primates are characterized by significant variation in patterns of brain growth. In addition, the degree to which brain growth is allocated to either the pre‐ or the postnatal period varies substantially. Analyses of phylogenetically adjusted data show no correlation between the lengths of the brain growth period and the juvenile period, but there are correlations with other life‐history variables. These results are explained in terms of maternal metabolic adaptations. Specifically, primates appear to present at least two major metabolic adaptations. In the first, brain growth occurs mainly during the prenatal period, reflecting heavy maternal investment. In the second, brain growth occupies large portions of the postnatal period. These differing patterns have important implications for maturation age, necessitating late maternal maturation in the first case and enabling relatively early maternal maturation in the second. Overall, these adaptations represent components of distinctive life‐history adaptations, with potentially important implications for the evolution of primate cognition. Am. J. Primatol. 62:139–164, 2004. © 2004 Wiley‐Liss, Inc.
Wild capuchins (cebus capucinus) fail to use tools
Authors: Garber P.A. , Brown E. 
Published: March 2004

AbstractFrom September through November 2000 we conducted an experimental field study of tool use in a group of 15 wild white‐faced capuchins (Cebus capucinus) in Costa Rica. The problem presented to the capuchins involved the use of wooden dowels as probes to obtain a food reward (two bananas) located inside a clear Plexiglas box. Specifically, the task required the capuchins to manually insert a dowel into any of six holes drilled into the box in order to push the bananas off a shelf. The banana could then be retrieved through a large opening at the bottom of the box. The capuchins visited the tool‐use platform 702 times over the course of 55 consecutive days and under several experimental conditions. During the first 21 days of the study, they explored the box but made no attempt to touch or pick up the dowels. Even after we placed the dowels in the holes, the capuchins only occasionally manipulated them. Overall, the results indicate that the capuchins did not use a tool to solve this novel foraging problem. Am. J. Primatol. 62:165–170, 2004. © 2004 Wiley‐Liss, Inc.
Use of spatial, visual, and olfactory information during foraging in wild nocturnal and diurnal anthropoids: A field experiment comparing Aotus, Callicebus, and Saguinus
Authors: Bicca‐Marques Júlio César , Garber Paul A. 
Published: March 2004

AbstractEarly in their evolution, the ancestors of anthropoid primates radiated from a nocturnal to a diurnal niche. Foraging during the night differs from foraging during the day in terms of the availability of light and color cues, and in the movement of odor molecules through the canopy. In this study, we compared the ability of nocturnal and diurnal New World monkeys to use perceptual cues (i.e., the sight or smell of food) and spatial information (place predictability) in within‐patch foraging decisions. An experimental field study was conducted on wild groups of night monkeys (Aotus nigriceps), tamarins (Saguinus imperator imperator and S. fuscicollis weddelli), and titi monkeys (Callicebus cupreus) at the Zoobotanical Park/UFAC, Rio Branco, Brazil. Our research design included the construction of feeding stations located in the home range of the study groups. Each feeding station consisted of eight visually identical feeding platforms located in a circular arrangement. In all test settings, two platforms at each feeding station contained a food reward (banana), and the remaining six platforms contained a sham reward (yellow plastic or inaccessible banana). In the night‐monkey experiments, each feeding platform was illuminated by a 40‐W red bulb to aid the researcher in observing their behavior. When the location of reward sites was predictable over time, individuals in all four species successfully relocated food rewards based solely on spatial information. Each species was also successful in using visual information to distinguish real from sham food rewards. However, only night monkeys and one group of emperor tamarins used olfactory information alone to locate food rewards. Overall, the species' performances did not clearly differentiate Aotus from diurnal New World primates in these experiments. Am. J. Primatol. 62:171–187, 2004. © 2004 Wiley‐Liss, Inc.
Significance of color, calories, and climate to the visual ecology of catarrhines
Authors: Dominy Nathaniel J. , Lucas Peter W. 
Published: March 2004

AbstractHere we describe correlations among visual ecology and the physiochemical properties of fruits and leaves consumed by four species of catarrhine primate:Cercopithecus ascanius,Colobus guereza,Pan troglodytes, andPiliocolobus badius. Collectively, their diet was diverse, with each species relying on fruits and leaves to different extents. The mean chromaticity of both foods, as perceived by the green‐red and yellow‐blue signals that catarrhines decode, was distinct from background foliage. However, selection on the basis of color was evident only for leaves. Primates consumed leaves with higher green‐red values than the leaves they avoided–sensory mechanism that correlated with key nutritional variables, such as increased protein and reduced toughness. Moreover, the monkeys ingested leaves near dusk, when reddish targets may be more salient. Similar patterns were never observed with respect to edible fruits, the chromaticities of which did not differ from unconsumed fruits or correlate with nutritional properties. We also found that primate biomass is higher in seasonal sites. We conclude that these findings are consistent with the notion that routine trichromatic vision evolved in a context where seasonal folivory was pivotal to survival. Am. J. Primatol. 62:189‐207, 2004. © 2004 Wiley‐Liss, Inc.
Paleoenvironmental basis of cognitive evolution in great apes
Authors: Potts Richard 
Published: March 2004

AbstractA bias favoring tree‐dominated habitats and ripe‐fruit frugivory has persisted in great ape evolution since the early Miocene. This bias is indicated by fossil ape paleoenvironments, molar morphology, dental microwear, the geographic pattern of extinctions, and extant apes' reliance on wooded settings. The ephemeral aspect of high‐quality fruit has placed a premium on cognitive and social means of finding and defending food sources, and appears related to great apes' affinity since the Miocene for wooded, fruit‐rich environments. These habitats have, however, undergone a severe withdrawal toward the low latitudes of Africa and Southeast Asia since the late Miocene, corresponding to a decline in the diversity of great apes beginning 9.5 million years ago. Plio‐Pleistocene records imply that wooded settings of Africa and SE Asia were prone to substantial fragmentation and coalescence. Once apes were confined to equatorial settings, therefore, habitat instability heightened the spatial/temporal uncertainty of ripe‐fruit sources. Prolonged learning, the assignment of attributes to distant places, mental representation, and reliance on fallback foods were all favored in this dynamic environmental context. These abilities helped sustain forest frugivory in most lineages. Fluid social grouping afforded the animals opportunities to locate ephemeral foods in continuous and fragmented forests. Fission‐fusion grouping also magnified the problems of object impermanence (of individuals) and dispersion manifested by food sources in the ecological realm. Thus the spatial and temporal dynamics of fruit and wooded habitats since the Miocene are reflected in important components of great ape cognition, foraging, and sociality. In contrast to great apes, cercopithecoid monkeys have increased their plant dietary options and diversified in seasonal environments since the late Miocene. Early hominins eventually severed the habitat bias that characterized the evolution of great apes, and later expanded into diverse environments. Am. J. Primatol. 62:209‐228, 2004. © 2004 Wiley‐Liss, Inc.
Human cognitive ecology: an instructive framework for comparative primatology
Authors: Keller Janet Dixon 
Published: March 2004

AbstractIn this review, research on human cognitive ecology is compared with studies of the cognitive ecologies of apes–especially the common chimpanzee. The objective was to assess the feasibility of extending an activity‐theory framework developed in studies of humans to an integrated approach for studying the cognitive accomplishments and skills of other primates living in the wild. Six generalizations were abstracted from studies of humans: 1) Social and material environments are arranged to facilitate production. 2) Human activity is shaped by conceptual and cultural principles that provide underlying logic for working knowledge and practice. 3) Schemata (multimodal, mental representations of procedures, strategies, and techniques) govern performance in a domain. 4) Working knowledge, skills, and social identities are coconstructed in communities of practice. 5) Rehearsal improves skilled performances, from which reputations as well as material products are derived. 6) Planning and emergence are in productive tension in human practices. These generalizations are applied to findings in the literature regarding the behavior of chimpanzees and other apes in the wild to assess the potential utility of a situated‐activity approach for comparative studies of primate cognition. It is argued in the Discussion that schemata constitute a common core of higher primate intelligence. Planning, emergence, and alterations of the environment to facilitate production further characterize human and chimpanzee or gorilla behaviors to varying degrees. Less apparent in the nonhuman‐primate literature is evidence of governing principles, rehearsal, and skill‐based reputations or identities entailing theories of mind. Nonetheless, recent observations in the wild suggest that further research is warranted to explore the rudiments of each of these components to enhance our understanding of the ecology of primate cognition and its evolutionary history. Am. J. Primatol. 62:229‐241, 2004. © 2004 Wiley‐Liss, Inc.
Effective enhancement of anticorrosive properties of polystyrene by polystyrene–clay nanocomposite materials
Authors: Yeh Jui‐Ming , Liou Shir‐Joe , Lin Chih‐Guang , Chang Yen‐Po , Yu Yuan‐Hsiang , Cheng Chi‐Feng 
Published: March 2004

AbstractA series of polymer–clay nanocomposite (PCN) materials consisting of polystyrene (PS) and layered montmorillonite (MMT) clay was prepared by effectively dispersing the inorganic nanolayers of MMT clay in the organic PS matrix via in situ thermal polymerization. Organic styrene monomers were first intercalated into the interlayer regions of organophilic clay hosts, followed by a typical free radical polymerization with BPO as the initiator. The as‐synthesized PCN materials were characterized by infrared spectroscopy (IR), wide‐angle powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). PCN coatings with low clay loading (1 wt %) on cold‐rolled steel (CRS) were found to be superior in anticorrosion to those of bulk PS, based on a series of electrochemical measurements of corrosion potential, polarization resistance and corrosion current in a 5 wt % aqueous NaCl electrolyte. The molecular weights of PS extracted from PCN materials and bulk PS were determined by gel permeation chromatography (GPC) with tetrahydrofuran (THF) as the eluent. The effects of material composition on molecular barrier and thermal stability of PS and PCN materials, in the form of both free‐standing films and fine powders, were also studied by molecular permeability analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1970–1976, 2004
One‐pot synthesis of polymeric bead bearing surface charge
Authors: Kusuktham Boonsri , Srikulkit Kawee 
Published: March 2004

AbstractPreparation of polymeric bead bearing surface charge was carried out by using one‐pot suspension polymerization of styrene and divinylbenzene (DVB) in the presence of cationic functional monomer, 3‐methacryloylamino) propyl trimethyl ammonium chloride (MAPTAC), by using K2S2O8 and AIBN as initiators. First, polymerization of MAPTAC in aqueous solution using K2S2O8 initiator was performed for the determined time to generate a PMAPTAC radical. Second, the mixture of styrene, DVB, and AIBN initiator was fed into the solution of PMAPTAC radicals and then allowed the polymerization to proceed for another specified time. During the stage of polymerization of styrene and DVB, incorporation of PMAPTAC radicals onto the bead surface took place, resulting in the final bead particle comprising two layers (from SEM results): the inner core of the poly(styrene‐co‐DVB) support and the outer layer of copolymerization adduct of styrene, DVB, and PMAPTAC radical revealed by FTIR analysis. Factors affecting particle size, size distribution, and surface functionality (PMAPTAC segment) were investigated. Of all synthetic parameters, types of surfactants and amounts of DVB were found to play an important role in controlling the particle size and the surface functionality, respectively. Nonionic surfactant (cetyl alcohol) tended to produce large particle size with a majority of the population falling in the range of 500‐1800 μm. Replacement of nonionic surfactant with cationic surfactant (CTAB) resulted in better control of particle size and size distribution because of its effective electrostatic stabilizer. An increase in the amount of DVB led to smoother bead surface as a result of less availability of styrene on bead surface, reducing surface charge density. The results of dye adsorption isotherm further confirmed that the cationic functional group was incorporated into the outer shell of the polymer bead. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1375–1387, 2004
Studies of polypropylene–intumescent flame‐retardant composites based on etched polypropylene as a coupling agent
Authors: Ma Zhi‐Ling , Gao Jun‐Gang , Bai Li‐Gai 
Published: March 2004

AbstractThe ammonium polyphosphate (APP)–pentaerythritol (PT)–melamine (M) system was selected as an intumescent flame retardant (IFR). The influence of dichromic acid–etched polypropylene (EPP) on the properties and compatibility of IFR/polypropylene (PP) composites was studied. The results obtained from mechanical tests and SEM showed that EPP was a true coupling agent for IFR/PP blends, but without changing the necessary flame retardancy. The cocrystallization between bulk PP and PP segments of EPP was confirmed by WAXD analysis. Flow tests showed that the flow behavior of composites in the melt is that of a pseudoplastic liquid, which is significant for EPP's effect on the rheological behavior of IFR/PP composite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1388–1391, 2004
Thermal oxidation of self‐degradable composite films based on low‐density polyethylene
Authors: Ol'Khov A. A. , Shibryaeva L. S. , Lordanskii A. L. , Zaikov G. E. 
Published: March 2004

AbstractThe effect of the structure of composite extrusion films based on a mechanical blend of low‐density polyethylene and poly(hydroxybutyrate) on the service characteristics and the kinetics of thermooxidative destruction was investigated. The aggregate state of the polymers affected the value of the boundary surface in the blend films. An increase in the latter affected the conformation states of both polymers in the blends. In this case, the strength decreased, the steam permeability increased, and the thermooxidative destruction of the polyethylene matrix during the beginning stages was accelerated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1392–1396, 2004
Polyester binders for wood containing benzotriazole and HALS light stabilizers
Authors: Sundell P. , Sundholm F. 
Published: March 2004

AbstractThree new polyester binders containing either benzotriazole‐type or hindered amine light stabilizers (HALS)‐type light stabilizers were synthesized. The binders were characterized by 13C and 1H NMR, FTIR, UV‐VIS spectroscopy, and size exclusion chromatography. It was found that it was possible to bind a benzotriazole‐type light stabilizer to the polymer backbone of the binder if a suitable group was present in the stabilizer. However, there was no proof that the HALS‐type stabilizer was bound to the binder. The average penetration depth of the binders into the radial surface of pine wood was mainly below 480 μm into earlywood and below 2500 μm into latewood. The average penetration depth into the tangential surface was around 1000 μm in the earlywood and around 2500 μm in the latewood. Artificial weathering causes a binder‐treated wood surface to darken independently of the binder used. The yellowness of the irradiated pine samples increased at the beginning of the exposure but decreased during longer exposure times. The benzotriazole stabilizer, Tinuvin 213, protected the surface of wood quite well; the other stabilizers were poor. The wood surface became rougher in appearance, cracks along the microfibril orientation became pronounced, and the bordered pits were degraded in the weathered samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1413–1421, 2004
Reduced copper diffusion in layered silicate/fluorinated polyimide (6FDA‐ODA) nanocomposites
Authors: Jiang Liang‐You , Wei Kung‐Hwa 
Published: March 2004

AbstractThe copper diffusion barrier properties of layered silicate/fluorinated polyimide nanocomposites were analyzed by transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS). It was found that the particles of copper are effectively retarded from penetrating into the polyimide matrix by layered silicates. The diffusion coefficients of layered silicate/polyimide nanocomposites are lower than that of the pure polyimide. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1422–1425, 2004
Bulk polymerization of styrene in the presence of polybutadiene: Effect of initiator type and prepolymerization conditions on particle morphology
Authors: Soto G. , Nava E. , Rosas M. , Fuenmayor M. , González I. M. , Meira G. R. , Oliva H. M. 
Published: March 2004

AbstractIn this study, we investigated the synthesis of high‐impact polystyrene through a series of (batch and bulk) polymerizations of styrene in the presence of 6 wt % polybutadiene. The reactions with rubber involved three stages: dissolution, prepolymerization, and finishing. The prepolymerizations were isothermal (at 70°C) and nonisothermal (with an initial heating period from 70 to 120°C). Purely thermal reactions were compared with chemically initiated polymerizations involving tert‐butyl peroctoate (TBPO), 2,2′‐azobisisobutyronitrile (AIBN), and their mixtures. Most prepolymerizations involved a stirring rate of 125 rpm. The particle morphology was mainly determined by the evolution of the grafting efficiency, stirring rate, and system viscosity during prepolymerization. In the nonisothermal prepolymerizations with pure AIBN, the grafting efficiency was lower than in equivalent prepolymerizations without an initiator, yielding unstable emulsions and a poor final morphology. In the nonisothermal prepolymerizations with pure TBPO, a large amount of graft copolymer was produced early in the prepolymerization, yielding a submicrometer core–shell morphology. The particle size and morphology could be controlled by the appropriate adjustment of the recipe and the prepolymerization conditions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1397–1412, 2004