bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of tert‐Butyl Methyl Ether (TBME) as an External Donor in Propene Polymerization with Dibutyl Phthalate (DBP)‐Containing MgCl2‐Supported Ti Catalysts Activated with Al(i‐C4H9)3
Authors: Ohnishi Rikuo , Konakazawa Takehito 
Published: September 2004

AbstractSummary: Stopped‐flow polymerization of propene was first conducted at 40 °C using the TiCl4/DBP/MgCl2 catalyst (DBP = dibutyl phthalate) combined with Al(C2H5)3. An induction period was observed at the beginning of polymerization, and the resulted polymer contained a considerable amount of the isolated ethylene unit. The formation of such unusual structures was concluded to be the result of copolymerization with ethylene originating from the ethylated Ti4+ species. Catalyst washing with toluene and stopped‐flow polymerization at 70 °C brought about a drastic decrease in the contents of both Ti and DBP as well as a disappearance of both the induction period and isolated ethylene unit. The microstructures of polymers revealed that the highly stereoregular polymers are produced at the initial stage of polymerization. Changes in yield and molecular weight of polymers with polymerization time showed that the addition of tert‐butyl methyl ether (TBME) brought about an increase in the concentration of active sites, but did not affect the propagation rate of propene polymerization. Such an increase in the active site concentration caused by an external donor has hardly been reported so far in kinetic studies using the stopped‐flow method; thus, the present result is believed to be a unique example.Kinetic curves of propene polymerization with the Cat. IV‐Al(i‐C4H9)3 catalyst. (•): with TBME/Al = 0.1 and hydrogen, (♦): with TBME/Al = 0.1 and without hydrogen, (○): without TBME and with hydrogen, (⋄): without TBME and hydrogen.magnified imageKinetic curves of propene polymerization with the Cat. IV‐Al(i‐C4H9)3 catalyst. (•): with TBME/Al = 0.1 and hydrogen, (♦): with TBME/Al = 0.1 and without hydrogen, (○): without TBME and with hydrogen, (⋄): without TBME and hydrogen.
“Inorganic and Organometallic Clusters and Polymers: Syntheses and Applications” Symposium
Authors: Harvey Pierre D. , Abd‐El‐Aziz Alaa S. 
Published: September 2004

AbstractConference Reports: This section contains reports on topical conferences. Reports are usually written at the request of the editorial office, but unsolicited contributions are also welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de.
Two applications of the curve lemma for orthogonal groups
Authors: Bruinier Jan Hendrik 
Published: September 2004

AbstractWe show (under some hypothesis in small dimensions) that the analytic degree of the divisor of a modular form on the orthogonal group O(2, p) is determined by its weight. Moreover, we prove that certain integrals, occurring in Arakelov intersection theory, associated with modular forms on O(2, p) converge. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Kreĭn's extension theory of nonnegative operators
Authors: Hassi Seppo , Malamud Mark , de Snoo Henk 
Published: September 2004

AbstractIn M. G. Kreĭn's extension theory of nonnegative operators a complete description is given of all nonnegative selfadjoint extensions of a densely defined nonnegative operator. This theory, the refinements to the theory due to T. Ando and K. Nishio, and its extension to the case of nondensely defined nonnegative operators is being presented in a unified way, building on the completion of nonnegative operator blocks. The completion of nonnegative operator blocks gives rise to a description of all selfadjoint contractive extensions of a symmetric (nonselfadjoint) contraction. This in turn is equivalent to a description of all nonnegative selfadjoint relation (multivalued operator) extensions of a nonnegative relation. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bound state solutions of the Dirac equation in the extreme Kerr geometry
Authors: Schmid Harald 
Published: September 2004

AbstractIn this paper we consider bound state solutions, i.e., normalizable time‐periodic solutions of the Dirac equation in an extreme Kerr black hole background with mass M and angular momentum J. It is shown that for each azimuthal quantum number k and for particular values of J the Dirac equation has a bound state solution, and that the energy of this Dirac particle is uniquely determined by $ \textstyle \omega = { {kM} \over {2J} } $. Moreover, we prove a necessary and sufficient condition for the existence of bound states in the extreme Kerr‐Newman geometry, and we give an explicit expression for the radial eigenfunctions in terms of Laguerre polynomials. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and Self‐Assembly of Styrene–[1]Dimethylsilaferrocenophane–Methyl Methacrylate Pentablock Copolymers
Authors: Datta Uttam , Rehahn Matthias 
Published: September 2004

AbstractSummary:Well‐defined pentablock copolymers of styrene–[1]dimethylsilaferrocenophane–methyl methacrylate (PMMA‐b‐PFS‐b‐PS‐b‐PFS‐b‐PMMA) are synthesized using lithium naphthalide as initiator and a 1,1‐dimethylsilacyclobutane‐mediated 1,1‐diphenylethylene (DPE) end‐capping technique. Annealing under various conditions followed by analysis by transmission electron microscopy revealed good phase separation by the copolymers and the presence of ordered microstructures, such as spheres‐on/in‐spheres, and spheres‐on/in‐lamellae micromorphologies.Structure of the styrene–[1]dimethylsilaferrocenophane–methyl methacrylate pentablock copolymers.magnified imageStructure of the styrene–[1]dimethylsilaferrocenophane–methyl methacrylate pentablock copolymers.
Unique Insertion Mode of 1,7‐Octadiene in Copolymerization with Ethylene by a Constrained‐Geometry Catalyst
Authors: Naga Naofumi , Toyota Akinori 
Published: September 2004

AbstractSummary: The copolymerization of ethylene and 1,7‐octadiene (OD) was investigated with a constrained‐geometry catalyst. The 13C NMR spectrum of the copolymer indicated cyclization insertion of the OD unit in the penultimate position after a single ethylene insertion step. This unique insertion mode of OD forms a 1,5‐disubstituted cyclononane unit in the main chain of polyethylene.Copolymerization of ethylene and 1,7‐octadiene (OD) with a constrained‐geometry catalyst.magnified imageCopolymerization of ethylene and 1,7‐octadiene (OD) with a constrained‐geometry catalyst.
Selectivity in Polystyryllithium Chain Coupling Induced by Monobromoalkane Additives
Authors: Ariura Fumi , Carlotti Stéphane , Deffieux Alain 
Published: September 2004

AbstractSummary: The end coupling of living PSLi chains in hydrocarbon media by the addition of monoalkylbromides has been examined. A very selective PS–PS coupling reaction was obtained with neo‐pentylbromide (94%) at a ratio of PSLi/alkylbromide equal to 1 while the secondary and tertiary bromine derivatives yield only very limited coupling. The coupling mechanism is likely to involve a lithium‐bromine interchange at the PS chain end, generating polystyryl‐bromide which then reacts selectively with the remaining polystyryllithium chains.
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Cover Picture: Macromol. Rapid Commun. 17/2004
Authors: Tezuka Yasuyuki , Tsuchitani Akiko , Oike Hideaki 
Published: September 2004

Cover: Polymeric topological isomers, theta‐shaped and manacle‐shaped polymers, have been synthesized from a polymer self‐assembly using a star telechelic poly(THF) having N‐phenylpyrrolidinium salt end groups carrying dicarboxylate counteranions. The two constitutional polymeric isomers were subsequently separated by means of a reversed‐phase liquid chromatography (RPC) technique. The picture shows that the theta‐ and manacle‐shaped polymers obtainable from linear and from star precursors are distinctive from each other with respect to the position of linking groups within their identical polymer framework, and it demonstrates the ability to place functional groups in specific locations in complex macromolecular topologies.Further details can be found in the Communication by Y. Tezuka,* A. Tsuchitani, and H. Oike on page 1531.
Persistence Length of Cartilage Aggrecan Macromolecules Measured via Atomic Force Microscopy
Authors: Ng Laurel , Grodzinsky Alan J. , Sandy John , Plaas Anna , Ortiz Christine 
Published: September 2004

AbstractTapping mode atomic force microscopy (TMAFM) was employed to directly calculate the persistence length of individual fetal bovine epiphyseal and mature nasal cartilage aggrecan monomers, as well as their constituent chondroitin sulfate glycosaminoglycan chains.
Morphology and Micromechanical Behaviour of SBS Block Copolymer Systems
Authors: Adhikari R. , Godehardt R. , Lebek W. , Goerlitz S. , Michler G.H. , Knoll K. 
Published: September 2004

AbstractBy means of transmission electron microscopy (TEM) and uniaxial tensile testing, the connection between the morphology and the micromechanical properties of selected styrene‐rich styrene/butadiene block copolymers was studied with respect to their molecular architecture. In particular, the structure‐property correlation of a lamellae forming asymmetric linear SBS triblock copolymer was examined by systematically varying the sample preparation techniques and testing temperature. The molecular architecture was found to influence directly the morphology formation of the block copolymers. Different mechanisms such as drawing of the lamellae, shearing in the rubbery phase and rotation of the lamellar axis were observed. From room temperature down to the temperature close to glass transition temperature of the soft phase, a homogeneous plastic drawing of glassy lamellae was perceptible.
Conductive Composite Materials of Polyethylene and Polypyrrole with High Modulus and High Strength
Authors: Zhu Dan , Bin Yuezhen , Oishi Kumiko , Fukuda Yasuyuki , Nakaoki Takahiko , Matsuo Masaru 
Published: September 2004

AbstractComposite films of polyethylene (PE) and polypyrrole (PPy) were prepared by polymerization of PPy on an ultradrawn polyethylene film with high modulus and high strength in ferric chloride (FeCl3) aqueous solution. The electrical conductivity of the composite film was found to be related to the polymerization conditions, such as polymerization temperature, polymerization time, the concentration and the oxidation potential of the FeCl3 solution. Scanning electron microscopy, FTIR and 13C NMR spectra were used to elucidate the morphological and structural variations of PPy prepared under different conditions, which lead to the differences in the electrical properties of the resultant composite films. The best electrical conductivity of the composite was about 5.5 S/cm for the film prepared under optimum conditions. The Young's modulus and the tensile strength reached 80 GPa and 3.2 GPa, respectively, which indicated the successful production of a conductive polymer with high strength and high modulus.
Failure Envelope Curves in Polyethylene Solids
Authors: Nitta Koh‐hei , Ishiburo Takashi 
Published: September 2004

AbstractThe present work demonstrates that the failure envelope analysis can be applied for characterizing the ultimate tensile properties of polyethylene solids in which the inhomogeneous necking process is avoided. As a result, the ultimate properties are essentially identical to those of vulcanized rubbers above the glass transition temperature, suggesting that tie molecules connecting the fragmented lamellar clusters transmit the external led to the fracture site in the same manner as cross‐linked rubbers do. Consideration of this crystal‐network model may provide information about the molecular processes that lead to rupture. Furthermore, the present analytical method can possibly be developed for predicting rupture times when different types of tests, such as constant drawn, constant stress and constant rate of stress, are conducted.
Side Chain Extension of Polypropylene by Aliphatic Diamine and Isocyanate
Authors: Kim K.Y. , Kim S.C. 
Published: September 2004

AbstractA post‐reaction modification of polypropylene by which to obtain increased melt strength is by reactive extrusion of randomly functionalized PP with polyfunctional monomers. In this study, reactive melt processing of maleated polypropylene (PP‐g‐MA) with poly[methylene (phenylene isocyanate)] (PMPI), hexamethylene diamine (HMDA), and poly(propylene glycol)‐bis‐(2‐propylamine) (Jeffamine D‐400) was carried out. The resulting chain‐extended PP‐g‐MA was confirmed by FTIR analysis. Its thermal and rheological properties were also measured. HMDA and D‐400 react with both the carboxylic acid and anhydride form of MA. Though PMPI only reacts with the carboxylic acid of MA, PP‐g‐MA reacted with PMPI has higher gel content and storage modulus compared to PP‐g‐MA reacted with the amine. This is because of the higher functionality of PMPI and localized reaction between the isocyanate in PMPI and the carboxylic acid in PP‐g‐MA.
Morphology and Temperature Phase Transitions in α,ω‐Alkanediols with Different Chain Lengths
Authors: Marikhin Vyacheslav , Egorov Victor , Ivan'kova Elena , Myasnikova Liubov , Radovanova Elena , Volchek Boris , Medvedeva Darya , Jonas Alan 
Published: September 2004

AbstractA comparative analysis of phase transitions in diols with various chain lengths [(CH2)44(OH)2 and (CH2)22(OH)2] and changes in their absorption spectra with temperature have been investigated by DSC and FTIR. Analysis of the DSC data has led to the conclusion that the low‐temperature phase transition of (CH2)22(OH)2 in a solid state (Ts‐s = 367.1 K) is a phase transition of the first order, while the high‐temperature phase transition (Tm = 376.3 K) is of the second order, i.e., a transition of the order‐disorder type. Splitting of the IR absorption bands into doublets at 720‐730 cm−1 and 1463‐1473 cm−1 indicates that crystalline subcells in the lamellae of both diols are orthorhombic lattices with the parameters typical of hydrocarbons. IR spectra showed that at the phase transition temperature Ts‐s transformation of an orthorhombic subcell into a hexagonal one occurs. This type of molecular chain packing remains the same up to the melting temperature Tm. In a (CH2)44(OH)2 diol, the ortho‐hexagonal subcell transition occurs only at the melting temperature (390.0 K). The wide IR band in the region from 3000 cm−1 to 3600 cm−1 shows that end hydroxyl groups of diol molecules form, on the surfaces of lamellar crystals, long (polymer) regular sequences consisting of intermolecular hydrogen bonds.
Visual kinesthesia and locomotion in Parkinson's disease
Authors: Schubert Martin , Prokop Thomas , Brocke Frank , Berger Wiltrud 
Published: September 2004

AbstractWe investigated predominance of visual control in Parkinson's disease (PD) gait regulation and whether visual kinesthesia has systematic effects on gait parameters. Effects of artificial optic flow were studied on walking velocity (WV), stride length (SL), and stride frequency (SF) during treadmill walking in PD patients and young and elderly adults. The independent variable was relative optic flow (rOF), ranging from −1 times (forward flow, i.e., in walking direction) to 3 times WV (backward flow, natural direction). All walkers were influenced similarly by rOF, inducing systematic changes of WV. Backward flow caused a decrease and forward flow an increase of WV. Without effect of rOF, PD patients on average walked at 0.89 meters per second compared to 1.31 meters per second in the age‐matched healthy group. The rOF‐induced mean changes of WV in all PD patients amounted to 0.45 meters per second (50.4%), with 45.1% due to changes in SL and 5.3% to SF. In the age‐matched, rOF‐induced WV changes reached 0.18 meters per second (13.8%), with 10.8% due to SL and 3.2% to SF. Thus, compared to the results of the age‐matched group, effects of rOF in PD patients were stronger, which increased WV to a normal level by normalization of SL. Contrary to the healthy subjects, no attenuation of optic flow effects over time was observed in the PD patients. Predominance of visual control in PD gait is suggested due to deficits in proprioception compensated by visual kinesthesia, causing exaggerated reaction to visual feedback. The results extend beyond earlier findings, generally stating improvement of PD gait by presence of visual feedback but show systematic effects on gait parameters due to reweighting of visual kinesthesia. © 2004 Movement Disorder Society
Non‐empirical calculations of NMR indirect carbon–carbon coupling constants. Part 10—Carbocages
Authors: Krivdin Leonid B. 
Published: September 2004

AbstractA comprehensive theoretical study of nine classical caged polycycloalkanes (tetrahedrane, prismane, homoprismane, quadricyclane, cubane, pentaprismane, hexaprismane, adamantane and diamantane) was carried out with special focus on the structural behavior of their J(C,C) values calculated at the SOPPA level. The structural behavior of J(C,C) in small carbocages is dominated by steric strain whereas in medium‐sized polycycloalkanes the J(C,C) values show no marked peculiarities and follow several well‐defined structural trends typical of other alicyclic compounds. Copyright © 2004 John Wiley & Sons, Ltd.
Neuroepileptic correlates of autistic symptomatology in tuberous sclerosis
Authors: Bolton Patrick F. 
Published: September 2004

AbstractTuberous sclerosis is a genetic condition that is strongly associated with the development of an autism spectrum disorder. However, there is marked variability in expression, and only a subset of children with tuberous sclerosis develop autism spectrum disorder. Clarification of the mechanisms that underlie the association and variability in expression will potentially throw light on the biological processes involved in the etiology of idiopathic forms of autism spectrum disorder. Current evidence indicates that the likelihood of a child with tuberous sclerosis developing an autism spectrum disorder is greater if the child has a mutation in the TSC2 gene, although autism can and does develop in children with TSC1 mutations. The likelihood is also greater if the child has early‐onset infantile spasms that are difficult to control, especially if there is an epileptiform focus in the temporal lobes. The emerging evidence is consistent with the notion that early onset electrophysiological disturbances within the temporal lobes (and perhaps other locations) has a deleterious effect on the development and establishment of key social cognitive representations concerned with processing social information, perhaps especially from faces. However, alternative mechanisms to account for the findings cannot yet be ruled out. Future research will have to employ prospective longitudinal designs and treatment trials to clarify the processes involved. MRDD Research Reviews 2004;10:126–131. © 2004 Wiley‐Liss, Inc.
Landau–Kleffner syndrome, electrical status epilepticus in slow wave sleep, and language regression in children
Authors: McVicar Kathryn A. , Shinnar Shlomo 
Published: September 2004

AbstractThe Landau–Kleffner syndrome (LKS) and electrical status epilepticus in slow wave sleep (ESES) are rare childhood‐onset epileptic encephalopathies in which loss of language skills occurs in the context of an epileptiform EEG activated in sleep. Although in LKS the loss of function is limited to language, in ESES there is a wider spectrum of cognitive impairment. The two syndromes are distinct but have some overlap. The relationship between the epileptiform EEG abnormalities and the loss of cognitive function remains controversial, even in LKS which is the most widely accepted as an acquired epileptic aphasia. Language regression also occurs in younger children, frequently in the context of a more global autistic regression. Many of these children have epileptiform EEGs. The term autistic regression with epileptiform EEG has been proposed for these children. Whether these children are part of an extended LKS spectrum is very controversial, because there are differences in age of onset, clinical phenotype, and EEG findings. An understanding of the available data on clinical characteristics, EEG findings, pathology, prognosis, and treatment of these syndromes is essential for further progress in this area. MRDD Research Reviews 2004;10:144–149. © 2004 Wiley‐Liss, Inc.
Detrusor overactivity in spina bifida: How long does it need to be treated?
Authors: AB Elisabeth , Dik Pieter , Klijn Aart J. , van Gool Jan D. , de Jong Tom P.V.M. 
Published: September 2004

AbstractAimsTo determine whether a lasting therapeutic effect can be expected from long‐term antimuscarinic therapy for neurogenic detrusor overactivity in spina bifida and to answer the question whether detrusor overactivity in spina bifida children with detrusor/sphincter dyssynergia is primarily based on the neuropathy or, in part, can be a secondary detrusor reaction to the functional urethral obstruction.MethodsFifteen spina bifida patients, aged between 1 and 12 years, all on a regime of clean intermittent catheterisation (CIC) and oxybutynin since shortly after birth, underwent three consecutive urodynamic studies (UDS). One prestudy UDS for treatment control, one UDS after withdrawal of oxybutynin for 3–5 days and one UDS after reinstallment of oxybutynin treatment. Urodynamic results were compared concerning detrusor overactivity, cystometric bladder capacity, and compliance.ResultsDetrusor overactivity was seen in two patients on the prestudy UDS. After several days of withdrawal of oxybutynin overactivity was seen in 11 patients. After oxybutynin withdrawal, bladder compliance was within safe margins for two patients only, after reinstallment, safe vesical pressures were seen in 11 patients.ConclusionThe functional obstruction due to detrusor/sphincter dyssynergia has been by‐passed chronically in all these children by CIC and oxybutynin. Due to the fact that detrusor overactivity recurs immediately after withdrawal of medication after long‐term treatment with oxybutynin, one can conclude that there is no long‐lasting therapeutic effect of pharmacological suppression. This suggests that in children with detrusor/sphincter dyssynergia, detrusor overactivity is primarily of neuropathic origin. © 2004 Wiley‐Liss, Inc.
Functional imaging of the human trigeminal system: Opportunities for new insights into pain processing in health and disease
Authors: Borsook David , Burstein Rami , Becerra Lino 
Published: September 2004

AbstractPeripheral inflammation or nerve damage result in changes in nervous system function, and may be a source of chronic pain. A number of animal studies have indicated that central neural plasticity, including sensitization of neurons within the spinal cord and brain, is part of the response to nervous system insult, and can result in the appearance of altered sensation, including pain. It cannot be assumed, however, that data obtained from animal models unambiguously reflects CNS changes that occur in humans. Currently, the only noninvasive approach to determining objective changes in neural processing and responsiveness within the CNS in humans is the use of functional imaging techniques. It is now possible to use functional magnetic resonance imaging (fMRI) to measure CNS activation in the trigeminal ganglion, spinal trigeminal nucleus, the thalamus, and the somatosensory cortex in healthy volunteers, in a surrogate model of hyperalgesia, and in patients with trigeminal pain. By offering a window into the temporal and functional changes that occur in the damaged nervous system in humans, fMRI can provide both insight into the mechanisms of normal and pathological pain and, potentially, an objective method for measuring altered sensation. These advances are likely to contribute greatly to the diagnosis and treatment of clinical pain conditions affecting the trigeminal system (e.g., neuropathic pain, migraine). © 2004 Wiley Periodicals, Inc. J Neurobiol 61: 107–125, 2004