bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyethylenes Having Well‐Defined Bimodal Molecular Weight Distributions Formed with Bis(phenoxy‐imine) Zr Complexes
Authors: Tohi Yasushi , Nakano Takashi , Makio Haruyuki , Matsui Shigekazu , Fujita Terunori , Yamaguchi Tsutomu 
Published: June 2004

AbstractSummary: Bis(phenoxy‐imine) Zr complexes with MAO activation can produce polyethylenes with well‐defined bimodal molecular weight distributions. Polymerization behavior indicates that minor changes in the ligand structures can have a significant effect on the modality of the resulting polyethylenes. Although there is no direct relationship between the bimodal catalytic behavior and the structure of a precatalyst complex in solution, a precatalyst complex having a methyl or methoxy group para to the phenoxy‐oxygen inclined to exhibit bimodal behavior whereas that with a pentafluorophenyl group on the imine‐nitrogen displayed unimodal behavior. Polymerization results suggest that bimodal behavior is linked to the presence of two kinds of cationic active species, which arise from different modes of ligand coordination. A qualitative correlation was found between the calculated amounts of possible cationic active species and the uni‐ and bimodal catalytic behavior. Based on the results obtained, we concluded that the bimodal polyethylenes are produced by two kinds of cationic active species having two available cis‐located sites with cis‐N, trans‐O and cis‐N, cis‐O arrangements. The results introduced herein are rare examples of the production of well‐defined bimodal polyethylenes using a single precatalyst.Bis(phenoxy imine) Zr complexes can produce well‐defined bimodal polyethylenes.magnified imageBis(phenoxy imine) Zr complexes can produce well‐defined bimodal polyethylenes.
Functionalization of Shortened Single‐Walled Carbon Nanotubes with Poly(p‐dioxanone) by “Grafting‐From” Approach
Authors: Yoon Kuk Ro , Kim Wan‐Joong , Choi Insung S. 
Published: June 2004

AbstractSummary: It has been a real challenge to form carbon nanotube (CNT)/polymer composites where CNTs are well‐dispersed in the polymer matrix and the interactions between CNTs and polymers are effectively strong. In this paper, we applied surface‐initiated, ring‐opening polymerization (SI‐ROP) of p‐dioxanone (PDX) to shortened single‐walled carbon nanotubes (s‐SWCNTs) and successfully formed s‐SWCNT/PPDX composites (see Figure). Due to intimate interactions between s‐SWCNTs and PPDX, we observed dramatic changes in PPDX properties upon the formation of the composites: 10%‐weight‐loss‐temperature of PPDX increased by 20 °C (measured by thermogravimetric analysis) and the patterns of Tg and Tm were greatly altered. We did not observe any noticeable peaks from the composite up to 120 °C in differential scanning calorimetry (DSC), while DSC data of PPDX itself showed Tg and Tm at −13.4 and 103 °C respectively.Schematic representation of the procedure for formation of s‐SWCNT/PPDX composites.magnified imageSchematic representation of the procedure for formation of s‐SWCNT/PPDX composites.
β‐Cyclodextrin Pseudopolyrotaxanes with π‐Conjugated Polymer Axles
Authors: Yamaguchi Isao , Kashiwagi Kohki , Yamamoto Takakazu 
Published: June 2004

AbstractSummary: β‐Cyclodextrin (β‐CD) pseudopolyrotaxanes containing poly(thiophene‐2,5‐diyl), PTh, or poly(3‐methylthiophene‐2,5‐diyl)s, P3MeThs, as an axle were prepared. Structures of the pseudopolyrotaxanes and their inclusion behavior with β‐CD were investigated. The UV‐vis measurements revealed that inclusion of P3MeThs by β‐CD depended on the flexibility of the main chain and their molecular weight.Formation of the inclusion complex of β‐CD and PTh.imageFormation of the inclusion complex of β‐CD and PTh.
The Formation of Ordered Nanoholes in Binary, Chemically Similar, Symmetric Diblock Copolymer Blend Films
Authors: Xuan Yu , Peng Juan , Wang Hanfu , Li Binyao , Han Yanchun 
Published: June 2004

AbstractSummary: Binary symmetric diblock copolymer blends, that is, low‐molecular‐weight poly(styrene‐block‐methyl methacrylate) (PS‐b‐PMMA) and high‐molecular‐weight poly(styrene‐block‐methacrylate) (PS‐b‐PMA), self‐assemble on silicon substrates to form structures with highly ordered nanoholes in thin films. As a result of the chemically similar structure of the PMA and the PMMA block, the PMMA chain penetrates through the large PMA block that absorbs preferentially on the polar silicon substrate. This results in the formation of nanoholes in the PS continuous matrix.An atomic force microscopy image of the thin film obtained from the blend of low‐molecular‐weight PS‐b‐PMMA and high‐molecular‐weight PS‐b‐PMA. The regular array of nanoholes in the films surface is clearly visible.imageAn atomic force microscopy image of the thin film obtained from the blend of low‐molecular‐weight PS‐b‐PMMA and high‐molecular‐weight PS‐b‐PMA. The regular array of nanoholes in the films surface is clearly visible.
Association Equilibria Theory for Polymers in Mixed Solvents with Specific Interactions
Authors: Soria Vicente , Figueruelo Juan E. , Abad Concepción , Campos Agustín 
Published: June 2004

AbstractSummary: Hydrogen bonding plays an important role in determining the physical and thermodynamic properties of polar fluids. Theoretical and experimental aspects of polymers, in mixed solvents with hydrogen‐bonding‐specific interactions, are investigated using a simple association model based on the theory of association equilibria developed by Pouchlý et al. The thermodynamic non‐idealities are accounted for using a modified Flory‐Huggins theory with effective gij parameters. The entropic term of the above formalism has been formulated taking into account the polymer segment‐solvent as well as the solvent‐solvent hydrogen‐bond formation. Four equilibrium constants are introduced to make a realistic picture between the associated and non‐associated species. By application of “multiple association equilibria theory”, sorption coefficients λ and Y have been deduced for the ternary systems with specific interactions i.e., alcohol(C1–C3)/heptan‐3‐one/poly(N‐vinyl pyrrolidone). Numerical values for the self‐association constants of the alcohols, association constants for the alcohols and ketone and for the alcohols and polymer, have been evaluated. These were determined as parameters adjusting best the predicted values of both preferential solvation, λ, and the second virial coefficient, A2, to experimental ones.Comparison of the theoretical (lines) and experimental (points) λ values as a function of propanol/heptan‐3‐one mixture composition for diverse poly(N‐vinyl pyrrolidone) samples. PVP‐K90 (, ×); PVP‐700K (, ⋄); PVP‐K40 (, ♦); PVP‐K24 (, ▴); and PVP‐K15 (, ▪).imageComparison of the theoretical (lines) and experimental (points) λ values as a function of propanol/heptan‐3‐one mixture composition for diverse poly(N‐vinyl pyrrolidone) samples. PVP‐K90 (, ×); PVP‐700K (, ⋄); PVP‐K40 (, ♦); PVP‐K24 (, ▴); and PVP‐K15 (, ▪).
Verschleißbeständige Fe‐Basislegierungen mit Niobkarbid
Authors: Theisen W. 
Published: June 2004

AbstractMartensitische Fe‐Basislegierungen des Systems Fe‐Cr‐C finden heute als Hartguss und Werkzeugstahl vielfältige Anwendung. Da ihre FeCr‐Karbide über eine relativ geringe Härte verfügen, wird in diesem Beitrag über neue Legierungen mit primär ausgeschiedenen härteren Niobkarbiden berichtet. Im Mittelpunkt stehen eine sekundär härtende, rissfrei aufschweißbare Hartlegierung, eine warmfester Schichtwerkstoff für Verbundguss, ein weißes Gusseisen und ein korrosionsbeständiger Kaltarbeitsstahl, die hinsichtlich ihrer herstellungsbedingten Gefüge analysiert und bezüglich Furchungsverschleiß untersucht wurden.
Mechanical Properties and Corrosion Resistance of Nitrided or Oxinitrided, and Powder Painted Regular and Interstitial Free (IF) Drawing Steel Sheet
Authors: Rogalski Z. , Łataś Z. 
Published: June 2004

AbstractSpecimens of 0.8 mm thick regular and interstitial free (IF) drawing steel sheet have been nitrided in fluidised bed for 2 hours at 620 °C and 560 °C with and without a post‐oxidation, and slow and accelerated cooling. As a result, surface hardness, yield and tensile strength of the sheets increased considerably without a critical loss of ductility. Resistance welds between the sheets did not lose their original strength after nitriding‐oxinitriding. Nitrided‐oxinitrided at 620 °C and then powder painted sheets, as compared with powder painted raw sheets, were more corrosion resistant in neutral salt spray and climatic tests. Some mechanical and anticorrosion properties of the IF steel sheet that had undergone the nitriding‐oxinitriding processes were definitely better than those of equally processed regular steel sheet.
Untersuchung von Schmelz‐ und Rekristallisationsprozessen sowie Riss‐, Oxid‐ und Porenbildung beim Schweißen
Authors: Abdurakhmanov R.U. , Saidov R.M. , Semmler U. , Matthes K.‐J. , Abdurakhmanov A.R. , Aitureev M.G. , Bohr A.R. 
Published: June 2004

AbstractDiskutiert werden verschiedene bekannte Methoden der Untersuchung der primären Rekristallisation und der Struktur der Kristallisationsfront. Diese Methoden besitzen eine Reihe von Nachteilen, haben z. T. eine eingeschränkte Aussagekraft und sind häufig sehr aufwändig. Die hier vorgestellte neue Methode basiert auf mikrofotografischer Aufzeichnung der schmelzenden und erstarrenden Metalloberfläche des Schweißbades. Die Nachteile bisheriger Methoden sind überwunden, wobei die neue Methodik neben der primären auch die Untersuchung der sekundären Rekristallisation sowie der Bildung von Rissen, Poren und nichtmetallischen Einschlüssen in der Schweißnaht erlaubt. Der Leistungsumfang der neuen Methodik wird anhand von Anwendungsbeispielen demonstriert.
Vorhersage des Ermüdungsrissausbreitungsverhaltens von Aluminiumlegierungen für Beanspruchungen mit variablen Mittelspannungen
Authors: Rödling S. , Bär J. , Gudladt H.‐J. 
Published: June 2004

AbstractFür realistische Lebensdauervorhersagen von rissbehafteten Bauteilen muss das Rissausbreitungsverhalten für wechselnde Beanspruchungsamplituden und variable Mittelspannungen bekannt sein. Dazu wurde ein Verfahren entwickelt, mit dem auf der Grundlage von nur zwei Rissausbreitungsexperimenten eine Vorhersage des Rissausbreitungsverhaltens für beliebige Mittelspannungen möglich ist. Neben einer Rissausbreitungskurve für ein konstantes Spannungsverhältnis R wird lediglich ein weiterer Versuch benötigt, bei dem der Schwellenwert durch eine Erhöhung der Unterspannung erreicht wird. Auf der Grundlage dieser beiden Versuche lassen sich die R‐Abhängigkeit des Schwellenwertes und die für entsprechende Rissfortschrittsrechnungen benötigten Konstanten vorhersagen. Das Verfahren liefert eine geschlossene Funktion zur Beschreibung der Rissfortschrittskurven für beliebige Spannungsverhältnisse. Die Modellrechnung wurde anhand experimenteller Daten für die Aluminiumlegierungen 6013 T62 und 2024 T351 verifiziert. Sie zeigt insgesamt sehr gute Übereinstimmungen mit dem Experiment. Die auf diese Weise ermittelbaren Ergebnisse stellen eine wichtige Grundlage für Betriebsfestigkeitsrechnungen an rissbehafteten Bauteilen, insbesondere bei Kollektiven mit variabler Mittelspannung, dar. Das vorgestellte Verfahren bietet somit eine schnelle und damit kostengünstige Möglichkeit zur vollständigen Ermittlung des Rissfortschrittsverhaltens unter variablen Mittelspannungen.
Quality of life in Polish patients with long‐lasting Parkinson's disease
Authors: Żach Marcin , Friedman Andrzej , Sławek Jarosław , Derejko Mirosława 
Published: June 2004

AbstractThe objective of this study was to evaluate possible relationships between quality of life (QoL) of Polish patients with long‐lasting Parkinson's disease and various demographic and clinical factors. The study comprised 141 patients of Movement Disorders outpatient clinics in Warsaw and Gdansk with at least 5 years of the disease duration. Mean age of patients was 68.09 ± 8.51 years, mean duration of disease was 11.87 ± 5.14 years. To assess the quality of life, the Parkinson's Disease Questionnaire (PDQ‐39) was used. Additional questions concerned duration of disease, initial and current treatment and expenses associated with therapy. Self‐perceived symptoms of depression were in our study the most important factor determining QoL. Duration of the disease and expenses related to the treatment also have a significant impact on the QoL. Patient's age and presence of dyskinesia seem to be irrelevant to the quality of life. © 2003 Movement Disorder Society
Parkinson's disease in Ireland: Clinical presentation and genetic heterogeneity in patients with parkin mutations
Authors: Wiley Joseph , Lynch Timothy , Lincoln Sarah , Skipper Lisa , Hulihan Mary , Gosal David , Bisceglio Gina , Kachergus Jennifer , Hardy John , Farrer Matthew J. 
Published: June 2004

AbstractEarly‐onset autosomal recessive parkinsonism is associated with parkin gene mutations. Different parkin mutations occur in many ethnic backgrounds; however, the phenotype may vary. We studied 102 young‐onset (age at onset <60 years) Parkinson's disease (PD) patients. From 102 patients, 40 with early‐onset PD (<45 years at symptomatic onset) were selected for clinical assessment and parkin gene molecular analysis for duplications/deletions and point mutations. We identified parkin mutations in 7 of 40 early‐onset patients; including novel compound heterozygotes and potential splice site changes. The mean age at onset in the 7 parkin mutation‐positive patients was 33 ± 9 years (age range, 18–42 years), marginally lower than that of the 33 parkin‐negative early‐onset patients, 38 ± 7 years (age range, 17–45 years). A family history of PD was present in 4 of 7 patients with parkin mutations, compared with 6 of 33 early‐onset parkin‐negative patients. Overall, parkin mutations were found in 4 of 10 patients with a positive family history and 3 of 30 patients without a family history of PD. Patients with parkin mutations had more dystonia, dyskinesia, and sleep benefit compared with parkin‐negative patients. We subsequently identified a single point mutation among the 62 young‐onset (age at onset 45 to <60 years). Mutations in the parkin gene may account for ∼17% of early‐onset (age at onset <45 years) parkinsonism in Ireland, in agreement with previous European studies. © 2003 Movement Disorder Society
Partial lesion of thalamic ventral intermediate nucleus after chronic high‐frequency stimulation
Authors: Henderson Jasmine , Rodriguez Michael , O'Sullivan Dudley , Pell Malcolm , Fung Victor , Benabid Alim Louis , Halliday Glenda 
Published: June 2004

AbstractA 73‐year‐old man with Parkinson's disease underwent thalamic stimulation for disabling tremor with excellent results only when stimulation on. Post‐mortem neuropathology (7 years postoperatively) revealed 60% cell loss within 0.5 mm of the electrode tip. Tremor improvement was attributable to chronic stimulation, not microthalamotomy. © 2004 Movement Disorder Society
Muscle relaxation is impaired in dystonia: A reaction time study
Authors: Buccolieri Alessandro , Avanzino Laura , Marinelli Lucio , Trompetto Carlo , Marchese Roberta , Abbruzzese Giovanni 
Published: June 2004

AbstractA simple visual reaction time (RT) paradigm was used to investigate whether the velocity of relaxation is impaired in dystonia. In 16 subjects with a clinical diagnosis of adult‐onset focal, segmental or multifocal dystonia and in 15 age‐matched normal controls, the relaxation reaction time (R‐RT) and the contraction reaction time (C‐RT) were compared across different tasks involving the flexor carpi radialis (FCR), biceps brachii (BB) and triceps brachii (TR) arm muscles. In normal controls, the latency of EMG termination (R‐RT) was significantly shorter than the latency of electromyographic (EMG) onset (C‐RT) in the BB and TR muscles, but not in the FCR muscle. In dystonic patients, the latency of EMG termination (R‐RT) was significantly longer than the latency of EMG onset (C‐RT) in the FCR and BB muscles. No significant difference of the C‐RT was observed between patients and controls whereas the R‐RT was prolonged significantly in the BB and TR muscles of patients with dystonia and almost significantly in the FCR muscle. This study indicates that muscle relaxation is abnormal in patients with focal (multifocal or segmental) dystonia. The impaired muscle relaxation may contribute to the longer overlap of agonist–antagonist activities (co‐contraction) typically observed in dystonia and to the slowness of voluntary movement sequencing. © 2004 Movement Disorder Society
A 100% increase of dopaminergic cells in the olfactory bulb may explain hyposmia in Parkinson's disease
Authors: Huisman Evelien , Uylings Harry B.M. , Hoogland Piet V. 
Published: June 2004

AbstractHyposmia is one of the most prevalent symptoms of Parkinson's disease. It may occur even before the motor symptoms start. To determine whether the olfactory dysfunctions, like the motor symptoms, are associated with a loss of dopamine, the number of dopaminergic cells in the olfactory bulb of Parkinson's disease patients was studied using tyrosine hydroxylase immunohistochemistry. The quantitative analysis reveals that the total number of tyrosine hydroxylase–immunoreactive neurons in the olfactory bulb is twice as high in Parkinson patients compared to age and gender‐matched controls. Because dopamine is known to inhibit olfactory transmission in the olfactory glomeruli, we suggest that the increase of dopaminergic neurons in the olfactory bulb is responsible for the hyposmia in Parkinson patients. The increase of dopamine in the olfactory bulb explains why olfaction does not improve with levodopa therapy. © 2004 Movement Disorder Society
Minocycline in Huntington's disease: A pilot study
Authors: Thomas Madhavi , Ashizawa Tetsuo , Jankovic Joseph 
Published: June 2004

AbstractMinocycline is a caspase inhibitor, decreases inducible nitric oxide synthase (iNOS), and has been shown to delay disease progression in the mouse model R6/2 of Huntington's disease (HD). This safety and tolerability study included 30 patients with HD who were given minocycline over a 6‐month period and underwent assessments every 2 months with laboratory studies, the Abnormal Involuntary Movements Scale, the Unified Huntington's Disease Rating Scale, and the Mini‐Mental State Examination. Minocycline was well tolerated during this study period and no serious adverse events were noted. © 2004 Movement Disorder Society
Cerebellar metabolic symmetry in essential tremor studied with 1H magnetic resonance spectroscopic imaging: Implications for disease pathology
Authors: Louis Elan D. , Shungu Dikoma C. , Mao Xiangling , Chan Steven , Jurewicz Eva C. 
Published: June 2004

AbstractThe pathological basis for essential tremor (ET) is not known; however, metabolic changes in the cerebellum can be observed in positron emission tomography (PET) and 1H magnetic resonance spectroscopic imaging (MRSI) studies. Tremor is relatively symmetric in ET, suggesting that underlying metabolic changes could be also symmetric. The degree of metabolic asymmetry in the cerebellum, however, has not yet been studied in ET, and knowledge about distribution and laterality of metabolic changes might shed some light on basic disease mechanisms. We measured brain metabolism (N‐acetylaspartate[NAA]/creatine [tCR]) to obtain an asymmetry index for cerebellar cortical metabolism ET patients compared with that in controls. This index, a percentage, was calculated as |(value right − value left)|/(value right + value left) × 100. Multislice 1H MRSI data were acquired for 20 patients and 11 controls. In ET patients, mean right and left cerebellar cortical NAA/tCR values were 1.61 ± 0.42 and 1.55 ± 0.38, respectively, compared with 1.81 ± 0.62 and 1.87 ± 0.49 in controls. The difference between right and left cerebellar cortical NAA/tCR was also calculated for each subject. In ET patients, the mean right‐left difference was 0.14 ± 0.11, compared with 0.32 ± 0.27 in controls (P = 0.016). The mean cerebellar cortical asymmetry index was low in ET (8.8 ± 6.1%), one‐half of that in controls (17.0 ± 13.7%, P = 0.027). These data suggest that pathological lesions in ET patients, which remain elusive, might be distributed similarly in each cerebellar cortex. Postmortem studies are needed to confirm these preliminary imaging results. © 2004 Movement Disorder Society
Neuropathology of primary restless leg syndrome: Absence of specific τ‐ and α‐synuclein pathology
Authors: Pittock Sean J. , Parrett Timothy , Adler Charles H. , Parisi Joseph E. , Dickson Dennis W. , Ahlskog J. Eric 
Published: June 2004

AbstractThe neuroanatomical substrate for restless legs syndrome (RLS) is unknown. We identified 4 patients with idiopathic RLS who came to post‐mortem examination, where brain and spinal cord tissue were available for neuropathological assessment. Lewy bodies were not identified and α‐synuclein immunohistochemistry was uniformly negative. Neurofibrillary tangle pathology was variable and nonspecific. These findings suggest that τ‐ or α‐synuclein brain pathology is not a component of primary RLS. Although chronic ischemic changes were found in all 4 cases, these were probably incidental. The absence of diagnostic microscopic brain or spinal cord pathology suggests that the pathologic substrate may be neurochemical or receptor based. © 2004 Movement Disorder Society
Restless legs syndrome due to interferon‐α
Authors: LaRochelle Jeffrey S. , Karp Barbara I. 
Published: June 2004

AbstractA patient developed restless legs symptoms paralleling the course of interferon‐α (IFNα) therapy for chronic hepatitis C. Symptoms began during a course of IFNα, resolved with its suspension, and recurred on rechallenge. Restless legs syndrome may thus be an adverse effect of IFNα treatment. © 2004 Movement Disorder Society
Reconstruction of the hand and upper limb with free flaps based on musculocutaneous perforators
Authors: Chen Hung‐Chi , Tang Yueh‐Bih , Mardini Samir , Tsai Bo‐Wen 
Published: June 2004

AbstractSince the advent of perforator flaps, a wide variety of applications have been documented. This study focuses on free flaps based on musculocutaneous perforators, because they have not been well‐described in the literature of upper‐limb reconstruction. They can be trimmed to be thin and pliable, and may provide large flaps with multiple components on the same pedicle to facilitate three‐dimensional inset of flaps. Microvascular free flaps based on musculocutaneous perforators were performed in 36 cases for reconstruction of the thumb and thenar web, palm, dorsum of the hand, wrist, and forearm. They included the anterolateral thigh perforator flap (27 cases), thoracodorsal perforator flap (5 cases), and deep inferior epigastric perforator flap (4 cases). In 2 other cases not included in this series, the thoracodorsal perforator flap could not be elevated due to anatomical variations. There was no failure in this series, but complications included: 1) hematoma in 2 cases, and 2) infection in 2 cases with flap rim necrosis which was treated by a local rotation flap and skin graft. The thin flaps facilitated secondary reconstructive procedures, and only minor effort was required for the debulking procedure of the flaps. On average, these patients required 2.3 occasions of secondary procedures for further reconstruction following coverage with a perforator flap. The perforator flaps provide medium‐thickness flaps for coverage of large defects in the upper limb with improved aesthetics and function. With careful dissection of the musculocutaneous perforators and primary thinning of the flaps, the use of a perforator flap is quite safe. Preservation of the muscles leads to better preservation of donor‐site functions. Less requirement of secondary debulking procedures is a great advantage. However, caution should be taken in the presence of wound infection. © 2004 Wiley‐Liss, Inc.