bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative Analysis of Hollow and Filled Polyelectrolyte Microcapsules Templated on Melamine Formaldehyde and Carbonate Cores
Authors: Sukhorukov Gleb B. , Shchukin Dmitry G. , Dong Wen‐Fei , Möhwald Helmut , Lulevich Valentin V. , Vinogradova Olga I. 
Published: March 2004

AbstractSummary: A comparative study of polyelectrolyte microcapsules templated on melamine formaldehyde (MF) and manganese carbonate (MnCO3) particles was performed using confocal Raman microscopy, scanning electron microscopy and by force measurements with an atomic force microscope. There is no significant difference between the properties of the shells templated on the MF and completely decomposable carbonate particles. In the case of capsules filled with polystyrene sulfonate (PSS), the MF oligomers formed a network complex with the polymer which resulted in a gel‐like structure in the interior. The existence of such a structure was proved by characteristic MF and PSS bands in Raman spectra, the bulky morphology of the dried capsules and much stiffer resistance to applied force as compared with PSS‐filled capsules templated on carbonate particles.SEM images of PSS‐loaded PAH/PSS capsules assembled on the on the MF template core.magnified imageSEM images of PSS‐loaded PAH/PSS capsules assembled on the on the MF template core.
Reactive Compatibilization of NBR/EPDM Blends by the Combination of Mercapto and Oxazoline Groups
Authors: Oliveira Marcia G. , Gomes Ana C. O. , Almeida Mauricio S. M. , Soares Bluma G. 
Published: March 2004

AbstractSummary: The reactive compatibilization of ethylene‐propylene‐diene (EPDM)/nitrile rubber (NBR) blends was performed using mercapto‐modified copolymers (mercapto‐modified EPDM, EPDMSH, and mercapto‐modified ethylene‐vinyl acetate copolymer, EVASH) in combination with oxazoline‐functionalized NBR (NBR‐ox). The best mechanical performance was achieved with the two EVASH‐based compatibilizing systems, especially the one containing the co‐reactive copolymers because of the reactivity of the oxazoline group. The presence of insoluble material in non‐vulcanized blends suggested the reactive compatibilization. The morphologies of these blends were examined through scanning electron microscopy (SEM). Blends compatibilized with the EVASH‐based systems showed finer morphologies than the non‐compatibilized blend or those compatibilized with the EPDMSH‐based systems. In non‐vulcanized NBR/EPDM (70:30 wt.‐%) blends, the presence of the co‐reactive EVASH/NBR‐ox system changes the morphology from a cocontinuous structure towards a droplet‐matrix morphology, and also results in a significant broadening of the damping curve related to the NBR transition, observed from DMTA analysis. The effect of the compatibilization on aging resistance has also been evaluated.SEM micrograph of a non‐vulcanized NBR/EPDM blend compatibilized with a NBR‐ox/EVASH co‐reactive copolymer.magnified imageSEM micrograph of a non‐vulcanized NBR/EPDM blend compatibilized with a NBR‐ox/EVASH co‐reactive copolymer.
Effects of the Reaction Conditions on the Syndiospecific Polymerization of Propene Promoted by Bis(phenoxyimine) Titanium Catalysts
Authors: Lamberti Marina , Pappalardo Daniela , Mazzeo Mina , Pellecchia Claudio 
Published: March 2004

AbstractSummary: The propene polymerization behavior of two typical bis(phenoxyimine) titanium catalysts has been investigated by varying reaction conditions, such as the monomer concentration, the solvent, and the cocatalyst. The experimental results indicate that the stereoregularity and regioregularity of the obtained poly(propylene)s are significantly affected by the reaction conditions. Fractionation of some poly(propylene) samples indicates the formation of macromolecules of different stereoregularity in the same run, suggesting that different active complexes can be generated in situ from these bis(phenoxyimine) titanium precatalysts.magnified image
Chain Extension of Carboxy‐Terminated Aliphatic Polyamides and Polyesters by Arylene and Pyridylene Bisoxazolines
Authors: Néry Laurent , Lefebvre Hervé , Fradet Alain 
Published: March 2004

AbstractSummary: The bulk reactions between carboxy‐terminated polyamide‐12 (PA12) or carboxy‐terminated poly(butane‐1,4‐diyl adipate) (PBDA) and 2,2′‐(1,3‐phenylene)bis(2‐oxazoline) (mbox), 2,2′‐(1,4‐phenylene)bis(2‐oxazoline) (pbox), 2,2′‐(2,6‐pyridylene)bis(2‐oxazoline) (pybox) as chain‐coupling agents were studied by size exclusion chromatography, carboxy end‐group titration, and NMR spectroscopy. The chain‐coupling reaction yielded high‐molar mass polymers within 20 to 180 min, depending on reaction temperature, starting oligomer molar mass, bisoxazoline/oligomer molar ratio, and the nature of bisoxazoline. No side‐reactions were observed. Bisoxazoline pybox, used for the first time in the bulk chain extension of carboxy‐terminated polymers, exhibited the highest reaction rates. The thermal properties of the resulting polymers, studied by differential scanning calorimetry and thermogravimetric analysis, are also discussed.The reaction of PBDA and PA12 with mbox, pbox, and pybox to give rise to the polymers studied here.magnified imageThe reaction of PBDA and PA12 with mbox, pbox, and pybox to give rise to the polymers studied here.
Synthesis and Surface Attachment of ABC Triblock Copolymers Containing Glassy and Rubbery Segments
Authors: Pyun Jeffrey , Jia Shijun , Kowalewski Tomasz , Matyjaszewski Krzysztof 
Published: March 2004

AbstractSummary: The synthesis of an ABC triblock copolymer containing glassy and rubbery segments was conducted using a combination of living anionic and atom transfer radical polymerizations (ATRP). A poly(dimethylsiloxane) (pDMS) macroinitiator ($\overline M _{{\rm n}\quad {\rm SEC}\;}$ = 6 200; $\overline M _{\rm w} /\overline M _{\rm n}$ = 1.19) was prepared by living anionic ring‐opening polymerization, followed by hydrosilation reactions to incorporate 2‐bromoisobutyrate end groups for initiation of ATRP. The ATRP of styrene (S) using the pDMS macroinitiator yielded a diblock copolymer ($\overline M _{{\rm n}\quad {\rm SEC}\;}$ = 66 730; $\overline M _{\rm w} /\overline M _{\rm n}$ = 1.38). Chain extension of the pDMS‐b‐pS macroinitiator with 3‐(dimethoxymethylsilyl)propyl acrylate (DMSA) by ATRP yielded an ABC triblock copolymer. The latter reactive segment was covalently attached to silanol groups on a silicon wafer. The presentation of either glassy pS or flexible pDMS segments of the brushes attached to the surface was reversibly controlled by treatment with selective solvents for each segment.Surface immobilization of pDMS‐b‐pS‐b‐pDMSA triblock copolymer to Si wafer. Treatment of brush with toluene, methanol, or annealing yields brush with hard pS surface. Treatment with hexane selectively solvates pDMS, and the soft layer is presented to the brush surface.magnified imageSurface immobilization of pDMS‐b‐pS‐b‐pDMSA triblock copolymer to Si wafer. Treatment of brush with toluene, methanol, or annealing yields brush with hard pS surface. Treatment with hexane selectively solvates pDMS, and the soft layer is presented to the brush surface.
Advanced 1H Solid‐State NMR Spectroscopy on Hydrogels, 2
Authors: Díez‐Peña Eva , Quijada‐Garrido Isabel , Barrales‐Rienda José Manuel , Schnell Ingo , Spiess Hans Wolfgang 
Published: March 2004

AbstractSummary: Advanced 1H solid‐state NMR methods are applied for studying the hydrogen bond formation occurring in polymer hydrogels based on N‐isopropylacrylamide (NIPAAm) and methacrylic acid (MAA). For P(NIPAAm‐co‐MAA) copolymers collapsed at low pH, two populations of water can be distinguished in 1H magic‐angle spinning (MAS) NMR spectra, one of which is probably situated near stable hydrogen‐bonded regions, while the other behaves similarly to free water. The pH‐induced polymer collapse can be followed in detail using 2D 1H‐1H double quantum (DQ) MAS NMR experiments on dried samples. For collapsed copolymers as well as interpenetrating polymer networks, the appearance of characteristic signals shows that hydrogen bonding takes place between NIPAAm and MMA monomers. The temperature dependence of the DQ spectra indicates that acid‐amide hydrogen bonds formed between both comonomers are more stable than the acid‐acid hydrogen bonds formed among MAA moieties alone. Correspondingly, by analyzing 1H‐1H DQ sideband patterns, a relatively short distance of 270 pm is found for the NIPAAm‐MMA hydrogen bond. Finally, the pH dependence of the DQ spectra demonstrates that hydrogen bonding phenomena are directly related to the polymer collapse.
magnified image
Advanced 1H Solid‐State NMR Spectroscopy on Hydrogels, 1
Authors: Díez‐Peña Eva , Quijada‐Garrido Isabel , Barrales‐Rienda José Manuel , Schnell Ingo , Spiess Hans Wolfgang 
Published: March 2004

AbstractSummary: The nature of the pH dependent collapse of poly(methacrylic acid) (PMAA) hydrogels is investigated using recent 1H solid‐state NMR methods. In aqueous solution, PMAA changes from an expanded conformation at high pHs to a compact contracted form at low pHs, where hydrogen bonds play a central role. In solid‐state 1H NMR spectra, recorded under fast magic angle spinning (MAS), dried PMAA samples previously collapsed at low pHs show characteristic signals in the spectral region of the carboxylic acid protons. With the aid of 2D 1H‐1H double‐quantum (DQ) MAS NMR spectra, three signals can be distinguished at 8, 10.5 and 12.5 ppm, which are attributed to free carboxylic groups and two different types of hydrogen bonded forms, respectively. The 12.5 ppm signal arises from the hydrogen bond with the shortest HH distance, corresponding to the form that is most stable with respect to increasing temperature and pH. The weaker hydrogen‐bonded form (with a signal at 10.5 ppm) requires a slightly lower pH, while the free acid signal (at 8 ppm) emerges under the most acidic medium. Moreover, the stabilities of the hydrogen‐bonded carboxylic acid dimers can be inferred from the proton‐proton distances within the dimers, i.e. (275 ± 5) pm and (295 ± 15) pm for the protons at 12.5 and 10.5 ppm, respectively, which are determined by means of DQ MAS sideband patterns. Both the stability of the hydrogen bonds and the acidity of the protons may be related to the stereochemistry and the conformation of the PMAA chains.
magnified image
Controlled Radical Polymerization of Vaporized Vinyl Monomers on Solid Surfaces under UV Irradiation
Authors: Yasutake Mikio , Andou Yoshito , Hiki Shigehiro , Nishida Haruo , Endo Takeshi 
Published: March 2004

AbstractSummary: In order to prepare well‐defined polymers on solid surfaces in the gas phase, a gas phase‐assisted surface polymerization (GASP) of vinyl monomers was carried out on solid surfaces pre‐coated with a photoiniferter, 2‐cyanoprop‐2‐yl N,N′‐dimethyldithiocarbamate, under UV irradiation. The GASP of methyl methacrylate (MMA) resulted in the formation of polymer on the surfaces and showed a proportional relationship between $\overline M _{\rm n}$ and polymer yield. Consecutive copolymerization of MMA and styrene led to the formation of a block copolymer, which was confirmed by a selective solvent fractionation method. These results demonstrate that controlled radical polymerization of vaporized monomer occurred on the solid surfaces.Expected mechanism of GASP under UV irradiation.magnified imageExpected mechanism of GASP under UV irradiation.
Blue Light Emission from a Fluorene‐Carbazole‐Fluorene Trimer Incorporated as the Side Chain into a Polynorbornene
Authors: Zaami Norredine , Slugovc Christian , Pogantsch Alexander , Stelzer Franz 
Published: March 2004

AbstractSummary: A well defined blue electroluminescent fluorene‐carbazol‐fluorene trimer 3,6‐bis‐(9,9‐dihexyl‐9H‐fluoren‐3‐yl)‐9‐alkyl‐9H‐carbazole was synthesized using a Suzuki type cross coupling reaction as the key step. A way to attach this chromophore to a norbornene was developed and the resulting electroactive monomer was polymerised using the “3rd generation Grubbs catalyst” (N,N‐bis(mesityl) 4,5‐dihydroimidazol‐2‐ylidene)(3‐bromo‐pyridine)2(Cl)2RuCHPh), yielding an amorphous polymer with a narrow molecular weight distribution, which was used to build a light‐emitting diode exhibiting electroluminescence peaking at 410 nm.Incorporation of the fluorene‐carbazol‐fluorene trimer as the emissive layer in an ITO/PEDOT:PSS/emitter/Ca/Al light emitting device.magnified imageIncorporation of the fluorene‐carbazol‐fluorene trimer as the emissive layer in an ITO/PEDOT:PSS/emitter/Ca/Al light emitting device.
The Structure of the Free Volume in Poly(styrene‐co‐acrylonitrile) from Positron Lifetime and Pressure Volume Temperature (PVT) Experiments
Authors: Dlubek Günter , Bondarenko Vladimir , Al‐Qaradawi Ilham Y. , Kilburn Duncan , Krause‐Rehberg Reinhard 
Published: March 2004

AbstractSummary: The structure of the free volume and its temperature dependence between 25 and 190 °C of copolymers of styrene with acrylonitrile, SAN (0 to 50 mol‐% AN), is studied by pressure volume temperature (PVT) experiments and positron annihilation lifetime spectroscopy (PALS). In this second part of the work, PALS data are reported from which the temperature dependence of the mean size and size distribution of local free volumes (subnanometer size holes) is analysed. The mean hole volume, vh, varies in PS between 105 Å3 (27 °C) and 220 Å3 (190 °C), and shows a systematic decrease with increasing AN content, at Tg from 121 Å3 for PS to 102 (±2) Å3 for SAN50. The specific number of holes, $N_{\rm h} '$, estimated from a comparison of PVT and PALS results, is independent on the temperature and the composition of SAN, $N_{\rm h} '$ = (0.56 ± 0.02) × 1021 g−1 which corresponds to Nh(Tg) = $N_{\rm h} '$/V(Tg) = 0.59 nm−3 and 1/Nh(Tg) = 1.7 nm3 for the volume which contains one hole. The analysed size distributions of the holes above Tg follow the compressibility of the free volume as it is predicted by the theory of thermal volume fluctuation. Moreover, we showed that the bulk elasticity modulus follows mastercurves as a function of vh above and below Tg.Free volume hole radius distribution n(rh) in PS for three different temperatures.magnified imageFree volume hole radius distribution n(rh) in PS for three different temperatures.
Soluble Polymethacrylates and Polystyrenes Containing Cationic Cyclopentadienyliron Moieties
Authors: Abd‐El‐Aziz Alaa S. , Todd Erin K. 
Published: March 2004

AbstractSummary: Cyclopentadienyliron coordinated chloroarenes were utilized to synthesize novel classes of cationic organoiron methacrylate and styrene monomers via metal‐mediated nucleophilic aromatic substitution reactions. These monomers were subsequently polymerized using a radical initiator to produce the corresponding organoiron polymers. Polymerization of olefin‐containing monomers containing terminal chloroarene complexes was also achieved by reaction with dinucleophiles yielding organoiron‐coordinated polyaromatic ethers and ether‐thioethers with pendent methacrylate or styrene moieties. These soluble polymers were subsequently crosslinked with a radical initiator, which resulted in the isolation of insoluble networks. Cyclic voltammetric investigations of these polymers showed that the pendent cationic iron centers underwent reversible reduction. Thermogravimetric analysis showed that the cyclopentadienyliron complexes were cleaved from the polymer backbones at approximately 220 °C, however; depending on the architecture of the polymer backbones, their structural integrities held from 320 to 470 °C. The solubilities of the polymethacrylates were much higher in comparison to polystyrene analogues and had weight average molecular weights between 22 500 and 86 400 with polydispersities ranging from 1.4 to 2.6. The molecular weights of the cationic organoiron polymers prepared via nucleophilic aromatic substitution polymerization ranged from 10 500 to 22 800 with polydispersities of 1.2 to 1.7.
magnified image
Fast Transient Fluorescence Technique for Studying Homopolymer Mobility in a Swelling Gel
Authors: Erdogan Matem , Pekcan Önder , Yagcι Yusuf 
Published: March 2004

AbstractSummary: The mobility of pyrene end‐capped polystyrene (Py‐PSt) trapped in swollen polystyrene gels (PSt) was investigated. PSt gels were prepared by free radical crosslinking copolymerization (FCC) of styrene (St) and ethylene glycol dimethacrylate (EGDM). The pyrene end‐capped polystyrene was produced by atom transfer radical polymerization (ATRP). After drying, these disc‐shaped PSt gels were left in a toluene solution of Py‐PSt of various molecular weights. During this process, Py‐PSt chains were trapped in the gel. These swollen gels were re‐dried in air and then immersed in pure toluene solution for monitoring the mobility of Py‐PSt chains in and out of the gel. These reswelling experiments were performed at room temperature in real time by monitoring pyrene lifetimes outside (τ1) and inside (τ2) of the PSt gel by using in‐situ fast transient fluorescence (FTRF) measurements. It was observed that τ2 values decrease as swelling proceeds; however, τ1 values stay constant during swelling. The Li‐Tanaka equation was employed to produce the swelling parameters. The swelling time constant, τc was found to increase as the crosslinker density of the gels and the molecular weight, $\overline M _{\rm n}$ of Py‐PSt chains were increased. It was observed that the collective diffusion coefficient, Dc decreased by increasing the molecular weight $\overline M _{\rm n}$ by obeying Dc ≈ M−1 law.Position of the PSt gel in the fluorescence quartz cell before (a) and after (b) swelling. I0 and Ip are the excitation and the emission intensities.magnified imagePosition of the PSt gel in the fluorescence quartz cell before (a) and after (b) swelling. I0 and Ip are the excitation and the emission intensities.
Cover Picture: Macromol. Chem. Phys. 4/2004
Authors: Erdogan Matem , Pekcan Önder , Yagcι Yusuf 
Published: March 2004

Cover: The cover shows the mobility of pyrene end‐capped polystyrene (Py‐PSt) trapped in swollen polystyrene (PSt) gel. Py‐PSt chain was produced by atom transfer radical polymerization (ATRP). Swelling experiments were performed in real time by monitoring pyrene lifetimes, outside (τ1) and inside (τ2) of PSt gel, by using fast transient fluorescence technique (inset in the Figure). The graph shows the variation of solvent uptake, W, of PSt gel against swelling time, ts.Further details can be found in the Full Paper by M. Erdogan, Ö. Pekcan,* Y. Yagcι on page 456.
Parkinson's prevalence estimated by a state registry
Authors: Strickland Daniel , Bertoni John M. 
Published: March 2004

AbstractA solid understanding of the descriptive epidemiology of a disease is essential in etiologic investigations; this includes prevalence and incidence, as well as groups within the larger community who may have noticeably lower or higher rates. We ascertained the usefulness of a non‐traditional registry in describing Parkinson's disease (PD) patterns in a community. A passive surveillance PD registry in Nebraska began data collection on 1 January 1997. All physicians were required to report PD diagnosis, pharmacists reported new prescriptions of anti‐PD drugs (PD cases were confirmed later with the prescribing physician), and there was a patient self‐report mechanism. The overlap of reporting by the sources allowed estimation of the number not reported by any source, using the statistical technique “capture–recapture.” As of January 2000, the Nebraska PD Registry had reports of 5,062 PD patients. The number not reported by any Registry reporting source was calculated to be 117, leading to an estimated total of 5,179 cases and a prevalence of 329.3 per 100,000 population. Tabulations of age‐ and gender‐specific prevalence rates, as well as county‐level estimates, allow examination of areas of elevated or lowered prevalence. The combination of a passive surveillance system and capture–recapture technique presents a useful method for epidemiologic description, and more traditional survey methods could benefit by including capture–recapture capability. © 2003 Movement Disorder Society
Gestes antagonistes in psychogenic dystonia
Authors: Munhoz Renato P. , Lang Anthony E. 
Published: March 2004

AbstractWe report on a patient with psychogenic craniocervical dystonia who had complete amelioration of her dystonia using typical gestes antagonistes. This exceptional case underlines the lack of specificity of these maneuvers for organic dystonia when confronted with more obvious clinical clues. © 2003 Movement Disorder Society
Cardiovascular effects of methamphetamine in Parkinson's disease patients
Authors: Pavese Nicola , Rimoldi Ornella , Gerhard Alexander , Brooks David J. , Piccini Paola 
Published: March 2004

AbstractCardiovascular responses after intravenous methamphetamine were assessed in 11 Parkinson's disease (PD) patients. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and electrocardiogram (ECG) were monitored for 103 minutes. After methamphetamine administration, SBP and DBP increased significantly in both PD and normal controls whereas placebo had no effect. In PD patients, however, the duration of SBP and DBP responses to methamphetamine and the maximum increase from baseline was attenuated compared with the controls. A significant correlation was found between individual BP responsiveness and the Unified Parkinson's Disease Rating Scale (UPDRS) motor score. These findings suggest that in PD there is impairment of catecholamine release from peripheral sympathetic presynaptic terminals, which correlates with motor impairment. © 2003 Movement Disorder Society
Reversal of hypertonic co‐contraction after bilateral pallidal stimulation in generalised dystonia: A clinical and electromyogram case study
Authors: Liu Xuguang , Tailor Jignesh , Wang Shouyan , Yianni John , Gregory Ralph , Stein John , Aziz Tipu 
Published: March 2004

AbstractIn a patient of generalised dystonia treated with bilateral pallidal stimulation, serial surface EMGs recorded from the neck muscles during alternating head movements revealed progressive reduction in hypertonic activity and reversal of co‐contraction to reciprocal contraction, which preceded clinical improvement. © 2003 Movement Disorder Society
Health‐related quality of life evaluation by proxy in Parkinson's disease: Approach using PDQ‐8 and EuroQoL‐5D
Authors: Martínez‐Martín Pablo , Benito‐León Julián , Alonso Fernando , Catalán Maria José , Pondal Margarita , Zamarbide Ivana 
Published: March 2004

AbstractPatient‐ and caregiver‐based scores were compared and agreement levels ascertained to determine the reliability of proxy evaluation of Parkinson's Disease (PD) patients' health‐related quality of life (HRQoL) using the EuroQoL and PD questionnaire (PDQ)‐8. Of 72 patient‐caregiver pairs, 64 (88.88%) returned the questionnaires. The degree of agreement varied for individual dimensions. Proxy evaluation of PD patients' HRQoL showed limitations mainly with assessments using the EuroQoL and especially in patients with severe disease and depression. © 2003 Movement Disorder Society
Long‐term follow‐up of cervical dystonia patients treated with botulinum toxin A
Authors: Haussermann Peter , Marczoch Stefanie , Klinger Christiane , Landgrebe Michael , Conrad Bastian , Ceballos‐Baumann Andres 
Published: March 2004

AbstractWe followed the course in 100 consecutive patients with cervical dystonia (CD) after they were initially treated with botulinum toxin (BTX) in the form of Dysport 10 to 12 years ago. A total of 4 patients had died, and 6 were lost to follow‐up. Of the remaining 90 patients, 57 (63%) were still treated with BTX. In the patients treated at one centre over the whole period with Dysport, mean dose used during each treatment session was 833 (SD ± 339) units Dysport with a cumulative dose of 20,943 (SD ± 9462) units Dysport over a mean of 26.8 (SD ± 8.6) treatment cycles. Secondary nonresponse was detected in 3 of the 90 patients. During follow‐up, 12 patients developed blepharospasm, 13 oromandibular dystonia, and 17 patients writer's cramp. We conclude that BTX remains effective and safe for approximately 60% of CD patients for more than 10 years. © 2003 Movement Disorder Society