bluuebunny/crossref_metadata_2025_split huggingface dataset:
CB1 cannabinoid receptor activation inhibits a neural correlate of song recognition in an auditory/perceptual region of the zebra finch telencephalon
Authors: Whitney Osceola , Soderstrom Ken , Johnson Frank 
Published: July 2003

AbstractA notable consequence of CB1 cannabinoid receptor activation in vertebrates is an impairment of cognitive function related to learning and short‐term memory. The mechanisms of this impairment remain unclear, but one possibility is that cannabinoids influence encoding of stimuli at sensory and/or perceptual levels. Here, by treating zebra finches with the cannabinoid agonist WIN55212‐2 and then measuring expression of the transcription factor zenk following presentation of novel zebra finch song, we show that cannabinoid receptor activation differentially influences zenk expression in sensory versus perceptual regions of the songbird auditory telencephalon. That is, WIN55212‐2 dose‐dependently inhibited zenk expression in a region for auditory perception (NCM, the caudomedial neostriatum), but had no effect on zenk expression in the primary auditory area, the Field L complex. The inhibitory effects of WIN55212‐2 on zenk expression in NCM were reversed by coadministration of the CB1‐selective antagonist SR141716A. Moreover, we found that the habituation of the NCM zenk response to repeated presentation of the same song, a well‐established neural correlate of song recognition, was blocked when birds were treated with WIN55212‐2 during habituation trials. Our data suggest that activation of CB1 cannabinoid receptors can selectively influence perceptual and mnemonic aspects of auditory experience. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 266–274, 2003
Synaptic plasticity and functionality at the cone terminal of the developing zebrafish retina
Authors: Biehlmaier Oliver , Neuhauss Stephan C.F. , Kohler Konrad 
Published: July 2003

AbstractPrevious studies have analyzed photoreceptor development, some inner retina cell types, and specific neurotransmitters in the zebrafish retina. However, only minor attention has been paid to the morphology of the synaptic connection between photoreceptors and second order neurons even though it represents the transition from the light sensitive receptor to the neuronal network of the visual system. Here, we describe the appearance and differentiation of pre‐ and postsynaptic elements at cone synapses in the developing zebrafish retina together with the maturation of the directly connecting second order neurons and a dopaminergic third order feedback‐neuron from the inner retina. Zebrafish larvae were examined at developmental stages from 2 to 7dpf (days postfertilization) and in the adult. Synaptic maturation at the photoreceptor terminals was examined with antibodies against synapse associated proteins. The appearance of synaptic plasticity at the so‐called spinule‐type synapses between cones and horizontal cells was assessed by electron microscopy, and the maturation of photoreceptor downstream connection was identified by immunocytochemistry for GluR4 (AMPA‐type glutamate receptor subunit), protein kinase β1 (mixed rod‐cone bipolar cells), and tyrosine hydroxylase (dopaminergic interplexiform cells). We found that developing zebrafish retinas possess first synaptic structures at the cone terminal as early as 3.5dpf. Morphological maturation of these synapses at 3.5–4dpf, together with the presence of synapse associated proteins at 2.5dpf and the maturation of second order neurons by 5dpf, indicate functional synaptic connectivity and plasticity between the cones and their second order neurons already at 5dpf. However, the mere number of spinules and ribbons at 7dpf still remains below the adult values, indicating that synaptic functionality of the zebrafish retina is not entirely completed at this stage of development. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 222–236, 2003
Accuracy in the outcomes and assessment information set (OASIS): Results of a video simulation
Authors: Madigan Elizabeth A. , Tullai‐McGuinness Susan , Fortinsky Richard H. 
Published: July 2003

AbstractThere is little information regarding the accuracy of the Outcomes and Assessment Information Set (OASIS), the patient assessment tool mandated for use in Medicare‐funded home health care. The purposes of this study were to evaluate the accuracy of OASIS completion by home health nurses and rehabilitation therapists, to compare responses of nurses and therapists, and to determine whether dispersion of answers would affect the home health resource group (HHRG) to which patients were assigned for Medicare home health care payments to agencies. Using a video simulation of admission and discharge visits, 436 clinicians from 29 Ohio home health care agencies scored selected OASIS items. Although the majority of the items were rated accurately, discrepancies were found between clinician responses and the “correct” answer on several items. Nurses and therapists provided similar ratings on most items studied, but for most cases in which discrepancies were found, nurses were more likely to agree with the “correct” answer. Discrepancies most often led to patients being assigned to lower‐payment HHRGs. Continued monitoring of OASIS data collection accuracy is recommended to maximize the value of the OASIS instrument in home health care research, practice, and policy. © 2003 Wiley Periodicals, Inc. Res Nurs Health 26:273–283, 2003
Reversal theory states and cigarette availability predict lapses during smoking cessation among adolescents
Authors: Burris Rebecca F. , O'Connell Kathleen A. 
Published: July 2003

AbstractAlthough 67% of adolescent smokers say they want to quit, only 7% are able to do so. The purpose of this study was to use metamotivational states as described in reversal theory to predict whether adolescents who are trying to quit smoking will lapse (smoke a cigarette) or will resist smoking in highly tempting situations. Reversal theory holds that individuals switch between telic (serious‐minded) and paratelic (playful) metamotivational states. Questionnaires and semistructured interviews were administered to 62 adolescents ages 14–19 who had participated in a smoking cessation program. Interviews were coded according to the Metamotivational State Interview and Coding Schedule, and the resulting data were analyzed using logistic regression analysis. Adolescents in the paratelic metamotivational state (OR = 15.34; 95% CI: 5.3, 43.6) or with cigarettes readily available (OR = 4.6; 95% CI: 1.6, 13.2) were more likely to lapse than were adolescents in the telic state or who required effort to obtain cigarettes. The variables telic/paratelic state and cigarette availability accurately predicted the outcome of highly tempting situations 80% of the time. Using reversal theory constructs to develop state‐specific strategies shows promise as an additional tool for those in this age group coping with the temptation to smoke. © 2003 Wiley Periodicals, Inc. Res Nurs Health 26:263–272, 2003
Preparation and characterization of microcapsulated red phosphorus and its flame‐retardant mechanism in halogen‐free flame retardant polyolefins
Authors: Wu Qiang , Lü Jianping , Qu Baojun 
Published: July 2003

AbstractMicrocapsulated red phosphorus (MRP), with a melamine–formaldehyde resin coating layer, was prepared by two‐step coating processes. The physical and chemical properties of MRP were characterized by Fourier‐transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) and other measurements. The flame retardant action and mechanism of MRP in the halogen‐free flame retardant (HFFR) polyolefins (PO) blends have been studied using cone calorimeter, limiting oxygen index (LOI), thermogravimetric analysis (TGA) and dynamic FTIR spectroscopy. The results show that the MRP, which is coated with melamine–formaldehyde resin, has a higher ignition point, a considerably lower amount of phosphine evolution and of water absorption compared with red phosphorus (RP) itself. The data observed by cone calorimeter, LOI and TGA measurements from the PO/HFFR blends demonstrated that the MRP can decrease the heat release rate and effective heat of combustion, and increase the thermostability and LOI values of PO materials. The dynamic FTIR results revealed the flame‐retardant mechanism that RP can promote the formation of charred layers with the P–O and P–C complexes in the condensed phase during burning of polymer materials. Copyright © 2003 Society of Chemical Industry
Synthesis and antitumour activity of medium molecular weight phthalimide polymers of camptothecin
Authors: Lee Neung‐Ju , Ju Sung‐Suk , Cho Won‐Jei , Kim Seon‐Hee , Kang Kyung‐Tae , Brady Thomas , Theodorakis Emmanuel A 
Published: July 2003

AbstractAttachment of anticancer agents to polymers has been demonstrated to improve their therapeutic profiles. A new monomer containing camptothecin, 5‐norbonene‐endo‐2,3‐dicarboxylimidoundecanoyl‐camptothecin (NDUCPT) and its homopolymer and copolymer with acrylic acid (AA) were synthesized and spectroscopically characterized. The NDUCPT content in poly(NDUCPT‐co‐AA) obtained by elemental analysis was 51%. The average molecular weights of the polymers determined by gel permeation chromatography were as follows: Mn = 12 100, Mw = 23 400 g mol−1, Mw/Mn = 1.93 for poly(NDUCPT), Mn = 15 400, Mw = 28 300 g mol−1, Mw/Mn = 1.83 for poly(NDUCPT‐co‐AA). The IC50 value of NDUCPT and its polymers against U937 cancer cells was larger than that of CPT. The in vivo antitumour activity of all polymers in Balb/C mice bearing the sarcoma 180 tumour cell line was greater than that of CPT at a dose of 100 mg kg−1. Copyright © 2003 Society of Chemical Industry
Synthesis and characterization of functionalized vinyl copolymers. Electronegativity and comonomer reactivity in radical copolymerization
Authors: Gatica Nicolás , Fernández Natalí , Opazo Alejandra , Alegría Sergio , Gargallo Ligia , Radic Deodato 
Published: July 2003

AbstractVinylsilane monomers (vinyltrimethoxysilane (VTMOS) and vinyltriethoxysilane (VTEOS)), methyl methacrylate (MMA), tert‐butyl acrylate (tBA) and N‐vinyl‐2‐pyrrolidone (VP) were used in the synthesis of functionalized vinyl copolymers. By using these monomers, VTMOS‐co‐MMA, tBA‐co‐VP and VTEOS‐co‐VP, with various compositions, were synthesized. The copolymers were characterized by viscometry, 1H‐NMR, FTIR and elemental analysis. The monomer reactivity ratios were estimated by the Fineman–Ross and Kelen–Tüdõs linear procedures. These parameters were also estimated by using a computer program based on a non‐linear minimization procedure known as Reactivity Ratios Error in Variables Model. Random copolymers and others containing blocks of one of the monomer units were obtained, depending on the chemical nature of the comonomers. The estimated comonomer sequence and distribution are discussed in terms of structural properties of the monomers such as molecular volume of the side groups, electronegativity of the substituents and steric hindrance. Analysis by comparison with other copolymers with analogous structures was also performed. Copyright © 2003 Society of Chemical Industry
A study on polyurethane/acrylate crosslinked gel polymer electrolytes
Authors: Xiaobin Huang , Tianbin Ren , Xian Zhao , Xiaozhen Tang 
Published: July 2003

Abstract2,4‐Toluene diisocyanate, poly(propylene glycol), poly(ethylene glycol) (PEG) and 2‐hydroxyethyl methacrylate were used to synthesize PEG–UA (urethane acrylate) monomer. The crosslinked polymer and gel polymer electrolytes were prepared in dioxane by free radical polymerization. The swelling behaviour, thermal degradation properties, morphology and ionic conductivity of the gel polymer electrolytes were investigated. With decrease in the proportion of dioxane used, the synthesized polymer's network density increased, its affinity with a solution of 1 M LiClO4 in propylene carbonate (PC) decreased, and more microgel which diffused in the network. At the same time, the conductivity increased and reached 4 × 10−4 S cm−1 at 25 °C. Copyright © 2003 Society of Chemical Industry
Synthesis and characteristics of radiation‐grafted membranes for fuel cell electrolytes
Authors: Liang Guo‐zheng , Lu Ting‐li , Ma Xiao‐yan , Yan Hong‐xia , Gong Zhao‐he 
Published: July 2003

AbstractProton exchange membranes were prepared by simultaneous radiation grafting of styrene onto polytetrafluoroethylene (PTFE) films at room temperature and subsequent sulfonation by chlorosulfonic acid. A series of grafted films with degree of grafting ranging from 0.947% to 35.4% were obtained. The effect of styrene concentration on the grafting yield was investigated and the maximum value was obtained at a monomer concentration of 70‐vol%. The structure of PTFE‐graft‐polystyrene sulfonic acid membranes was studied by infrared spectroscopy. The membrane properties, such as water uptake, ion exchange capacity, swelling performance and ionic resistance, were studied as functions of the degree of grafting. The thermal and chemical stability of the sulfonic acid membranes was also investigated. The membrane properties were found to depend on the degree of grafting and the amorphous character of the membrane structure, and the better membrane properties were obtained at a degree of grafting in the range 12–21%. Copyright © 2003 Society of Chemical Industry
Synthesis and characterization of poly(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol) segmented block copolymers
Authors: Zhang Yong , Feng Zeng‐Guo , Zhang Ai‐Ying 
Published: July 2003

AbstractPoly(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol) segmented random copolymers, with poly(butylene succinate) (PBS) molar fraction (MPBS) varying from 10 to 60 %, were synthesized through a melt polycondensation process and characterized by means of GPC, NMR, DSC and mechanical testing. The number‐average relative molecular mass of the copolymers was higher than 4 × 104 g mol−1 with polydispersity below 1.9. Sequence distribution analysis on the two types of hard segments by means of 1H NMR revealed that the number‐average sequence length of PBT decreased from 2.80 to 1.23, while that of PBS increased from 1.27 to 4.76 with increasing MPBS. The random distribution of hard segments was also justified because of the degree of randomness around 1.0. Micro‐phase separation structure was verified for the appearance of two glass transition temperatures and two melting points, respectively, in DSC thermograms of most samples. The crystallinity of hard segments changed with the crystallizability controlled by the average sequence length and reached the minimum value at an MPBS of about 50–60 mol%. The results can also be ascribed to the co‐crystallization between two structurally analogous hard segments. Mechanical testing results demonstrated that incorporating a certain amount of PBS moieties (less than 30 mol%), at the expense of a minute depression of the elastic modulus, that higher relative elongation and more flexibility of polymer chain could be expected. Maximum equilibrium water absorption and faster degradation rates were observed on samples with higher MPBS values and lower crystallinity of hard segments were better hydrophilicity of the polymer chain, through in vitro degradation experiments. Copyright © 2003 Society of Chemical Industry
Role of short polyisoprene chains in storage hardening of natural rubber
Authors: Ngolemasango F , Ehabe E , Aymard C , Sainte‐Beuve J , Nkouonkam B , Bonfils F 
Published: July 2003

AbstractDrying of natural rubber (NR) crumb (grade TSR10) requires high temperatures (100–120 °C). In order to determine the changes in bulk viscosity during the drying process, ageing kinetics at 120 °C were studied on model NR samples. During the process, changes in Mooney viscosity and weight‐average molar mass (MW) were monitored. Rubber from clones GT 1 and PR 107, with a bimodal inherent molar mass distribution (MMD0), was degraded in a two‐phase process. During the first phase, Mooney viscosity and MW increased, undoubtedly owing to a predominance of storage hardening over chain scissions [0 < t (min) <120]. During the second phase, chain scissions predominated (t > 120 min) and Mooney viscosity and MW decreased. For rubber samples from clone PB 217, with a unimodal MMD0, no or reduced storage hardening was observed throughout the ageing process. These results showed that the key parameter involved in storage hardening seems to be the quantity of short polyisoprene chains and probably the nature of the chain ends. Copyright © 2003 Society of Chemical Industry
Model experiments for a molecular understanding of polymer crystallization
Authors: Reiter Günter 
Published: July 2003

AbstractTime‐resolved real‐space observations of morphology and pattern formation resulting from crystallization of ultrathin films of low‐molecular‐weight poly(ethylene oxide) (PEO) or diblock copolymers containing PEO shed light on the mechanisms of how polymer crystals are formed. We used simple but restricted geometries like thin films of controlled thickness or confinement resulting from block copolymer mesotructures. Under such conditions, we were able to relate the observed morphology and its temporal evolution directly to molecular processes and the kinetics of crystal growth. We demonstrate that changes in the morphology with time are due to different thermal histories and are the consequence of the mestable nature of polymer crystals. Information about the nucleation process was obtained by examining crystal formation in 12‐nm small spherical cells of a block copolymer mesostructure. We discuss the advantages of thin‐film studies for a better understanding of polymer crystallization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1869–1877, 2003
Biodegradable electrospun mat: Novel block copolymer of poly (p‐dioxanone‐co‐L‐lactide)‐block‐poly(ethylene glycol)
Authors: Bhattarai Narayan , Cha Dong Il , Bhattarai Shanta Raj , Khil Myung Seob , Kim Hak Yong 
Published: July 2003

AbstractUltrafine fibers of a laboratory‐synthesized new biodegradable poly(p‐dioxanone‐co‐L‐lactide)‐block‐poly(ethylene glycol) copolymer were electrospun from solution and collected as a nonwoven mat. The structure and morphology of the electrospun membrane were investigated by scanning electron microscopy, differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and a mercury porosimeter. Solutions of the copolymer, ranging in the lactide fraction from 60 to 80 mol % in copolymer composition, were readily electrospun at room temperature from solutions up to 20 wt % in methylene chloride. We demonstrate the ability to control the fiber diameter of the copolymer as a function of solution concentration with dimethylformamide as a cosolvent. DSC and WAXD results showed the relatively poor crystallinity of the electrospun copolymer fiber. Electrospun copolymer membrane was applied for the hydrolytic degradation in phosphate buffer solution (pH = 7.5) at 37 °C. Preliminary results of the hydrolytic degradation demonstrated the degradation rate of the electrospun membrane was slower than that of the corresponding copolymers of cast film. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1955–1964, 2003
Nanostructure evolution in a poly(ether ester) elastomer during drawing and the displacement of hard domains from lamellae
Authors: Stribeck Norbert , Funari Sérgio S. 
Published: July 2003

AbstractA poly(ether ester) thermoplastic elastomer with a soft block content of 50 wt % has been studied with synchrotron small‐angle X‐ray scattering (SAXS) during strain/relaxation cycles. The rigid nodes of the elastic network are not the hard domains themselves but instead are ordered three‐dimensional assemblies of several hard domains. At a critical elongation, single hard domains are disrupted and dislocated from these assemblies in a peculiar manner. In the ultimate structure, remaining pairs of hard domains form (semi)elastic nodes. The complex two‐dimensional SAXS patterns indicate stacks from tilted lamellae that are destroyed when the sample is strained to double its initial length. With multidimensional chord distribution function analysis, the complex nanostructure and its evolution in the draw experiment have been analyzed. The fundamental hard domains are not lamellae but cylinders (5 nm × 8 nm) arranged on a lattice at cylindrical coordinates (r12, r3), which are given by the intersections of r3(r12) = ±1.5r12 ± 13nmn, n being a natural number. A semielastic component is made from hard domains forming other lamellar assemblies, which are characterized by n = 3/2. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1947–1954, 2003
Phenol‐urea‐formaldehyde cocondensed resol resins: Their synthesis, curing kinetics, and network properties
Authors: He Guangbo , Riedl Bernard 
Published: July 2003

AbstractSeveral phenol‐urea‐formaldehyde (PUF) cocondensed resol resins were synthesized by different procedures. The curing kinetics and network properties of these PUF resins were examined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). A kinetic study indicated that the activation energy values of PUF resins are generally higher than those of phenol‐formaldehyde (PF) resins during curing processes, but the curing rates of PUF resins are faster than those of PF resins. The pH values of PUF systems have a significant influence on the rate constants, although they affect the activation energy very slightly. Moreover, the dependence of activation energy on the conversion showed that there are more individual reactions with different activation energies occurring during the curing processes in PUF resins than in PF resins. The decomposition of methylene ether bridges to form methylene bridges probably occurs at high temperature in PUF resins. DMTA data indicated that the network rigidity of PUF resins is slightly lower than that of PF resin. The gel point and Ttan δ2 transition measured by DMTA were consistent with the kinetic results obtained from the DSC data, but they were also related to the physical and mechanical properties of the network, especially with regard to the Ttan δ2 transition. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1929–1938, 2003
Mean‐field and fluctuation correction analyses for a diblock copolymer melt exhibiting an immiscibility loop
Authors: Cho Junhan , Kwon Yong K. 
Published: July 2003

AbstractA study on a diblock copolymer melt that can form certain specific interactions between dissimilar monomers is performed first with a mean‐field approach and then with a fluctuation correction approach. Flory's interaction parameter χ possesses both enthalpic and entropic contributions because of the specific interactions. It is found that not only a lower critical ordering transition but also an immiscibility loop with an upper critical ordering transition can be developed in the copolymer by the presence of the specific interactions and the entropic component in χ. The mean‐field loop phase diagram is shown to feature a typical sequence of microphase transitions upon both heating and cooling with two continuous transition points at a symmetric composition. It is revealed that the fluctuation effects remove both continuous transition points to significantly shrink the loop. The pressure effects on the phase behavior of the copolymer are also discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1889–1896, 2003