bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cortical control of spatial memory in humans: The visuooculomotor model
Authors: Pierrot‐Deseilligny Charles , Müri René M. , Rivaud‐Pechoux Sophie , Gaymard Bertrand , Ploner Christoph J. 
Published: October 2002

AbstractWe review current knowledge of the cortical control of spatial memory, studied using visuooculomotor paradigms. Spatial memory is an essential cognitive process that can be involved in preparing motor responses. Our knowledge of spatial memory in humans recently has progressed thanks to the use of ocular saccades as a convenient model of motor behavior. Accuracy of memory‐guided saccades, made to the remembered locations of visual targets, is a reflection of spatial memory. For the performance of memory‐guided saccades with brief delays (up to 15–20 seconds), that is, involving short‐term spatial memory, lesion studies have shown that the posterior parietal cortex, the dorsolateral prefrontal cortex, and the frontal eye field play significant roles. Studies of memory‐guided saccades using transcranial magnetic stimulation have suggested that the right posterior parietal cortex is involved at the initial stage (<300 milliseconds) of visuospatial integration, whereas the dorsolateral prefrontal cortex in both hemispheres controls the following phase of short‐term memorization, the frontal eye field mainly serving to trigger saccades. The new concept of a medium‐term spatial memory has emerged from a behavioral study of memory‐guided saccades in normal subjects, showing a paradoxical spontaneous improvement of spatial memory after delays of approximately 20 seconds. Lesion studies have shown that the parahippocampal cortex could specifically control this medium‐term spatial memory. Last, different experimental and clinical arguments suggest that, after a few minutes, the hippocampal formation finally takes over the control of spatial memory for long‐term spatial memorization. Therefore, spatial memory involved in the memorization of visual items could be successively controlled by the dorsolateral prefrontal cortex (short‐term spatial memory), the parahippocampal cortex (medium‐term spatial memory), and the hippocampal formation (long‐term spatial memory), depending on specific periods of times. The applicability of this simple visuooculomotor model of spatial memory to other types of stimuli and general motoricity has yet to be confirmed.
Miscibility and morphology of poly(vinylidene fluoride)/poly[(vinylidene fluoride)‐ran‐trifluorethylene] blends
Authors: Gregorio Rinaldo , Chaud Matheus Rigobelo , Nunes Dos Santos Wilson , Baldo João Baptista 
Published: October 2002

AbstractThis study presents an investigation of the effect of the different crystalline phases of each blend component on miscibility when blending poly(vinylidene fluoride) (PVDF) and its copolymer poly[(vinylidene fluoride)‐ran‐trifluorethylene] [P(VDF–TrFE)] containing 72 mol % of VDF. It was found that, when both components crystallized in their ferroelectric phase, the PVDF showed a strong effect on the crystallinity and phase‐transition temperature of the copolymer, indicating partial miscibility in the crystalline state. On the other hand, immiscibility was observed when both components, after melting, were crystallized in their paraelectric phase. In this case, however, a decrease in crystallization temperatures suggested a strong interaction between monomers in the liquid state. Blend morphologies indicated that, in spite of the lack of miscibility in the crystalline state, there is at least miscibility between PVDF and P(VDF–TrFE) in the liquid state, and that a very intimate mixture of the two phases on the lamellar level can be maintained upon crystallization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1362–1369, 2002
Preparation and characterization of polystyrene–clay nanocomposites by free‐radical polymerization
Authors: Tseng Chen‐Rui , Wu Jeng‐Yue , Lee Hsin‐Yi , Chang Feng‐Chih 
Published: October 2002

AbstractThe polymerizable cationic surfactant, vinylbenzyldimethylethanolammouium chloride (VBDEAC), was synthesized to functionalize montmorillonite (MMT) clay and used to prepare exfoliated polystyrene–clay nanocomposites. The organophilic MMT was prepared by Na+ exchanged montmorillonite and ammonium cations of the VBDEAC in an aqueous medium. Polystyrene–clay nanocomposites were prepared by free‐radical polymerization of the styrene containing intercalated organophilic MMT. Dispersion of the intercalated montmorillonite in the polystyrene matrix determined by X‐ray diffraction reveals that the basal spacing is higher than 17.6 nm. These nanocomposites were characterized by differential scanning calorimetry (DSC), transmission electron micrograph (TEM), thermal gravimetric analysis (TGA), and mechanical properties. The exfoliated nanocomposites have higher thermal stability and better mechanical properties than the pure polystyrene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1370–1377, 2002
Effect of radiation on the crosslinking and branching of polypropylene
Authors: Gao Jianming , Lu Yujie , Wei Genshuan , Zhang Xiaohong , Liu Yiqun , Qiao Jinliang 
Published: October 2002

AbstractTo make crosslinked polypropylene (PP) and PP with high melting strengths, we studied the effects of radiation on the crosslinking and branching of PP in detail with the Charlesby–Pinner (C–P) equation. We studied the radiation crosslinking and branching behavior of homopolypropylene (HPP), impact copolypropylene (IPP), and random copolypropylene (RPP) and used the C–P equation for some parameter calculations. We found that (1) the C–P equation seemed applicable when PP with a multifunctional crosslinking agent was irradiated within a certain dose range in air and (2) IPP had the highest gel dose value, crosslinking G value/scission G value, and gel fraction after irradiation among HPP, RPP, and IPP; therefore, IPP is the best material for making radiation crosslinking and radiation branching PP among HPP, RPP, and IPP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1758–1764, 2002
Adhesion of electrochemically formed polypyrrole coatings to low carbon steel
Authors: Iroh Jude O. , Su Wencheng 
Published: October 2002

AbstractThe lap shear strength of polypyrrole coatings formed on low carbon steel (∼ 23 MPa) is shown to be significantly higher (by ∼ 60%) than that obtained using uncoated steel as the adherend. The lap shear (adhesion) strength of polypyrrole‐coated steel varied with the pH of the monomer–electrolyte solution and the applied current. The low carbon steel‐containing polypyrrole coatings formed at low pH (pH ≤ 2.4) have higher adhesion strength than those coated with polypyrrole at higher pH (pH ≥ 6.0). However, poly(N‐methyl pyrrole)‐coated steel showed significantly lower adhesion strength. Increasing the applied current density decreased the adhesion strength. The surface free energies of polypyrrole coatings, ∼ 49–53 mJ/m2 are similar to that obtained for uncoated low carbon steel, ∼ 53 mJ/m2, indicating that polypyrrole will effectively wet low
rbon steel. The extent of wetting of low carbon steel by the coatings was additionally confirmed by an interaction parameter, ϕ, of unity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2757–2763, 2002
Synthesis and properties of high oil‐absorbent 4‐tert‐butylstyrene‐EPDM‐divinylbenzene graft terpolymer
Authors: Zhou Mei Hua , Cho Won‐Jei 
Published: October 2002

AbstractThe graft crosslinking polymerization of 4‐tert‐butylstyrene (tBS) and divinylbenzene (DVB) onto ethylene–propylene–diene (EPDM) was carried out in toluene by using benzoyl peroxide (BPO) as an initiator. The synthesized graft terpolymer, tBS‐EPDM‐DVB (PBED), was extracted with tetrahydrofuran (THF) into gel (called as PBED I) and sol, and then they were identified by infrared (IR) spectroscopy. The effects of solvent amount, molar ratio of DVB to tBS, EPDM content, initiator concentration, reaction temperature, and reaction time on the graft crosslinking polymerization were examined. Among them, solvent amount and molar ratio of DVB to tBS were the important factors for this reaction system. Maximum oil absorbency of PBED I was 84.0 g/g but its oil‐absorption kinetic rate was very low. Sol PBED can be reused as oil absorbent (named as PBED II) through photocrosslinking by ultraviolet light irradiation. Although the oil absorbencies of PBED II were lower than those of PBED I in most cases, their oil absorption kinetic rates were higher than oil absorbencies of PBED I. The highest value of oil absorbency of PBED II was 56.0 g/g. The thermal stability of PBED I was studied by TGA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2119–2129, 2002
Friction of linerboard based on recycled fiber
Authors: Garoff Niklas , Nilvebrant Nils‐Olof , Fellers Christer 
Published: October 2002

AbstractThe purpose of this investigation was to study the origin of the differences in paper‐to‐paper friction of linerboards based on old corrugated containers (OCC). The sheets were subjected to two extraction stages and analyzed with respect to, surface roughness, and their content of low‐molecular‐mass lipophilic compounds (LLC). Friction was measured using a friction tester based on the horizontal plane principle. The surface roughness was measured using a Perthometer profiler and the low molecular mass lipophilic constituent of the paper sheets was determined by gas chromatography‐mass spectroscopy. The sheets were imaged using environmental scanning electron microscopy (ESEM), and the relative compositions of inorganic ions on the paper surfaces were determined by energy dispersive X‐ray spectroscopy (EDS). The results showed that a high amount of LLC in the sheets lead to low friction, due to lubrication. It was also observed that large CaCO3 particles on the surface had a friction‐increasing effect, and that there was no relationship between the surface roughness and the friction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1511–1520, 2002
Crystallization and melting characteristics of metallocene isotactic polypropylenes
Authors: Fujiyama Mitsuyoshi , Inata Hitoshi 
Published: October 2002

AbstractThe measurement of crystallization and melting behaviors under constant rates of cooling and heating and the Avrami's analysis of isothermal crystallization were carried out for various metallocene‐ (MET‐PP) and Ziegler‐ Natta‐catalyzed (ZN‐PP) random polypropylene copolymers with various ethylene contents. Both the melting pointTmand the crystallization temperatureTcdecrease with increasing ethylene content. Compared at the same ethylene content, both are lower for MET‐ PP because of the higher uniformities of stereoirregular bonds and copolymerization bonds.TmandTcshow a linear correlation, and compared at the sameTc,Tmof MET‐PP is lower than that of ZN‐PP. This is because MET‐PP has narrower distributions of isotactic sequence length and hence of lamellar thickness than ZN‐PP. The heat of fusion and the latent heat of crystallization decrease with ethylene content. At the same ethylene content, both are lower for MET‐PP, owing also to the higher uniformities of stereoirregular bonds and copolymerization bonds. From the Avrami's analysis, it is assumed that there is little difference in crystallization modes of both catalyst PPs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1851–1857, 2002
Dynamic mechanical properties of dental base material reinforced with glass fiber
Authors: Karacaer Özgül , Doğan Arife , Doğan Orhan Murat , Usanmaz Ali 
Published: October 2002

AbstractDynamic mechanical properties of poly(methyl methacrylate) (PMMA) reinforced with glass fibers were investigated. The composite used as dental base material contained other additives for different purposes to give the same appearance as natural dentals. The fiber–polymer bonding and orientation of fibers in polymer matrix are very important in the application of the product. To see that, the fibers were treated with silane and compared with untreated fibers. The commercial polymer and monomer used were the heat‐cured type. However, in addition to heat curing, γ‐radiation was also used in curing. This gives much improved material in terms of mechanical properties. The voids, which cause mechanical failure in the material, will be minimal in number with irradiation curing. The results showed that the orientation of all fibers were not regular. This could be observed from the micrographs and DMA behaviors of samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1683–1697, 2002
Flow behavior of enhanced oil recovery Alcoflood polymers
Authors: Ghannam Mamdouh , Esmail Nabil 
Published: October 2002

AbstractFlow behavior in terms of shear stress and viscosity versus shear rate is investigated for aqueous solutions of Alcoflood polymer materials. Rheostress RS100 is employed for operating, measuring, and analyzing this experimental investigation. Polymer concentration in the range of 100–10,000 ppm was covered. Fitting analysis is carried out for all the examined polymer solutions. Casson and Ostwald‐de‐Waele correlations can be employed for predicting flow behavior, depending upon polymer type. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2896–2904, 2002
Effect of meta‐dihydroxy benzene as a surface modifier on filler–filler and filler–polymer interaction of carbon black polymer composite
Authors: Ganguly S. , Chakraborty S. , Banerjee A. N. , Bhattacharya P. 
Published: October 2002

AbstractIn the present context an attempt was made to use polyhydroxybenzene on rubber‐grade carbon black to suitably modify the surface morphology and hence to achieve improved thermomechanical and mechanical dynamic properties. FTIR studies clearly point out the presence of excess hydroxyl group in the modified black. The improvement in mechanical properties is attributed to higher crosslink density through hydrogen bonding and oxygen bridge participation during the covulcanization reaction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2025–2033, 2002
Electrical properties of poly(propylene terephthalate)
Authors: Motori Antonio , Saccani Andrea , Sisti Laura 
Published: October 2002

AbstractDirect current (dc) and alternating current (ac) electrical behavior of a laboratory‐synthesized semicrystalline poly(propylene terephthalate) is investigated. The dc charging/discharging currents and electrical conductivity are studied as a function of temperature and time of applied voltage. The conduction mechanisms are pointed out and related to the structural characteristics of the polymer. The ac properties (dielectric constant and loss factor) are investigated over a wide temperature and frequency range. The relaxation processes, which take place in the material, are disclosed and their origin is analyzed. The electrical behavior of poly(propylene terephthalate) is finally related to that shown by other thermoplastic polyesters. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2271–2275, 2002
Influence of centrifugal field on free‐radical polymerization kinetics
Authors: Boodhoo K. V. K. , Dunk W. A. E. , Jachuck R. J. 
Published: October 2002

AbstractIt has been observed that when a prepolymer mix of styrene, poly(styrene), toluene, and benzoyl peroxide is transferred from a conventional stirred tank reactor (STR) to a spinning disc reactor (SDR), the rate of polymerization is substantially increased. Furthermore, the molecular weight and the molecular weight distribution of the polymer formed at conversions up to about 80% in the SDR is virtually unchanged from that of the polymer formed at 60% conversion in the STR. These results seem to indicate that the increase in polymerization rate is not the result of the well‐known Trommsdorff–Norrish effect, which would be expected to lead to an increase in polydispersity. We believe that shear and centrifugal forces experienced by the film provide intense mixing and extension flow effects, which are responsible for the above‐described observations. In this report an explanation has been put forward to describe the observed effects. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2283–2286, 2002
Synthesis and structure of the poly(methyl methacrylate) microlatex
Authors: Dan Yi , Yang Yunhua , Chen Sanyu 
Published: October 2002

AbstractMicroemulsion polymerization is a new approach for preparing nanosize polymer materials. In this article, a nanosize poly(methyl methacrylate) (PMMA) was prepared by a novel microemulsion polymerization. The kinetics of the polymerization and the effects of the temperature, the monomer, and emulsifier/water ratio on the polymerization were investigated by means of the conversion, the transmittance, and the refractive index measurements. The structure of the obtained PMMA microlatex was studied through transmission electron microscopy (TEM), nuclear magnetic resonance (1H‐NMR), and differential scanning calorimetry (DSC). The results show that the polymerization exhibits typical kinetic characteristics of a microemulsion polymerization, i.e., there only exists two rate stages: a stage of increasing rate, and a stage of decreasing rate, and no constant rate stage is observed during the polymerization. The obtained PMMA microparticles are very uniform, regular, and small, being about 17–33 nm in the number‐average diameter. The polymer has higher molecular weight (1.71 × 106 viscosity average molecular weight), higher tacticity (51% syndiotacticity), and higher glass transition temperature (127°C), much different from the commercial PMMA. Experimentally, a stable and transparent PMMA microlatex with higher polymer content (30–40 wt %), lower weight ratio of emulsifier to water (E/W ≤ 0.03) and emulsifier to monomer (E/M ≤ 0.05) as well as smaller particle size (dp < 40 nm), has been prepared, which is very important for the industrialization of the microemulsion polymerization technique. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2839–2844, 2002
Controlled release of biocides in solid wood. I. Efficacy against brown rot wood decay fungus (Gloeophyllum trabeum)
Authors: Liu Y. , Laks P. , Heiden P. 
Published: October 2002

AbstractNanoparticles containing the fungicides tebuconazole or chlorothalonil were prepared with median diameters of ∼ 100–250 nm. The nanoparticle matrices were polyvinylpyridine (PVP), copolymers of PVP and styrene (PVP‐co‐St), and blends of PVP and hyperbranched polyesters (HBPs). The isolated nanoparticles were resuspended in water to yield suspensions able to deliver 0.1, 0.2, 0.4, and 0.8 kg fungicide/m3 of wood. Southern yellow pine (SYP) was treated with these suspensions using conventional vacuum‐pressure treatments. Less concentrated suspensions delivered the nanoparticles quantitatively into the SYP while suspensions capable of delivering up to 0.8 kg of the fungicide (the active ingredient or AI) per cubic meter of SYP delivered 0.4–0.7 kg AI/m3, depending on the nanoparticle matrix. The SYP lost less than 5% of its mass after 55 days of exposure to Gloeophyllum trabeum when the tebuconazole content in the SYP reached 0.2 kg/m3, and the matrix identity had little effect on the results. The SYP lost between 3 and 6% of its mass after 55 days of exposure to G. trabeum when the AI was chlorothalonil at a level of ∼ 0.6 kg AI/m3 of wood and was introduced into SYP in nanoparticles with a PVP/HBP matrix, but it lost ∼ 11% of its mass at the same AI levels when the nanoparticle matrix was PVP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 596–607, 2002
Solid state polymerization (SSP) of low molecular weight poly(ethylene terephthalate) (PET) copolyesters compared to conventional SSP of PET
Authors: Schiavone Robert J. 
Published: October 2002

AbstractSSP, starting from very low molecular weight (MW) poly(ethylene terephthalate) (PET) precursors, is claimed to offer significant production cost advantages over conventional PET production. However, as the intrinsic viscosity (IV) of the PET precursor is reduced, there is a significant change in the crystallization behavior of PET and morphology that affects reactivity in SSP. Using small particle size PET to significantly reduce the effects of diffusion so that SSP is under chemical reaction control and using a kinetic model that describes an overall SSP rate, the effect of ethylene isophthalate substitution on the SSP rate from low MW PET precursor was determined. As the ethylene isophthalate comonomer content increases, the rate of SSP for low MW PET increases. The activation energy for SSP of low MW PET decreases with an increase in the ethylene isophthalate content. For the low MW PET copolyesters in this study, the SSP activation energy is comparable to conventional process when the comonomer content of the low MW polyester is around 7 mol % and the conventional precursor is around 3 mol %. However, even though the activation energy is reduced through the use of higher comonomer content, the overall rate of SSP for the low MW copolyesters studied is significantly slower than conventional SSP. This reduction in rate is explained by differences in crystallinity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 230–238, 2002
A fluorine gas monitoring system for the direct oxy‐fluorination of polyethylene sheets
Authors: Kasai Toshi , Aya Tetsuya , Ohara Hidehiko 
Published: October 2002

AbstractA new technique is presented to measure the concentration of fluorine in a reaction gas consisting of fluorine, nitrogen, and oxygen in a reaction chamber. The method is described as follows: The gas is directly taken from the chamber using a peristaltic pump and dissolved in a TISAB (total ionic strength adjusted buffer) solution. The concentration of fluorine ion is measured using the selected fluorine ion electrode, the output voltage of which is monitored. The concentration of the fluorine ion and the output voltage follow the Nernst relation so that the measurement of the output voltage of the system enables us to know the concentration of fluorine gas. This technique was applied to monitor the concentration of fluorine gas in the chamber in which a sheet of polyethylene nonwoven fabric was continuously oxy‐fluorinated. The monitored concentration of the fluorine gas as a function of time coincided with the variation of the incorporated fluorine in the sheet measured by X‐ray fluorescence (XRF) spectroscopy after the treatment. This technique can be best used for process control of the continuous oxy‐fluorination of polymeric materials. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 684–691, 2002