bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early‐onset cerebellar ataxia (EOCA) with retained reflexes: Reduced cerebellar benzodiazepine‐receptor binding, progressive metabolic and cognitive impairment
Authors: Mielke RÜDiger , Hilker RÜDiger , Weber‐Luxenburger Gerald , Kessler Josef , Heiss Wolf‐Dieter 
Published: May 2005

AbstractA family with two members who had early‐onset cerebellar ataxia (EOCA) with retained tendon reflexes had, in addition to their motor deficits, a progressive impairment of cognitive and visuospatial abilities. We used positron emission tomography (PET) with 11C‐flumazenil to study gammaaminobutyric type A/benzodiazepine receptor binding (BZR) and 18F‐2‐fluoro‐2‐deoxy‐D‐glucose to analyze longitudinally regional cerebral glucose metabolism. Flumazenil‐PET demonstrated loss of BZR binding that has not been shown in Friedreich's ataxia and olivopontocerebellar atrophy. These findings may be useful for differentiation of EOCA from other types of cerebellar ataxia. In comparison to age‐matched control subjects, these patients showed a global metabolic decline and predominant hypometabolism in the thalamus and cerebellum. The progressive metabolic derangement may be explainable by a disturbed integrity of cognition‐related networks resulting from secondary degeneration of cerebello‐thalamo‐cortical projections.
Adjuncts to dopamine replacement: A pragmatic approach to reducing the problem of dyskinesia in Parkinson's disease
Authors: Brotchie Jonathan M. 
Published: May 2005

AbstractDyskinesias following long‐term dopamine replacement therapy are a major limitation of current treatments for Parkinson's disease. Recently, attention has been focused on the concept of using non‐dopaminergic adjuncts to currently available therapies in an attempt to reduce the problem of dyskinesia. Thus, an enhanced understanding of the neural mechanisms underlying dyskinetic symptoms has led to the realization that it might be possible to manipulate non‐dopaminergic systems and reduce dyskinesia without compromising the antiparkinsonian efficacy of drugs such as L‐dopa. This article discusses how non‐dopaminergic manipulations could reverse the abnormalities in basal ganglia circuitry responsible for generating dyskinesia. It is proposed that potential anti‐dyskinetic drugs might include glutamate (NMDA) receptor antagonists, opioid receptor antagonists, cannabinoid receptor agonists or antagonists, α2 adrenergic receptor antagonists, and 5‐HT‐enhancing agents.
PTK787/ZK222584, a tyrosine kinase inhibitor of vascular endothelial growth factor receptor, reduces uptake of the contrast agent GdDOTA by murine orthotopic B16/BL6 melanoma tumours and inhibits their growth in vivo
Authors: Rudin Markus , McSheehy Paul M. J. , Allegrini Peter R. , Rausch Martin , Baumann Diana , Becquet Mike , Brecht Karin , Brueggen Josef , Ferretti Stephane , Schaeffer Fabienne , Schnell Christian , Wood Jeanette 
Published: May 2005

AbstractAssessment of tumour vascularity may characterize malignancy as well as predict responsiveness to anti‐angiogenic therapy. Non‐invasive measurement of tumour perfusion and blood vessel permeability assessed as the transfer constant, Ktrans, can be provided by dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI). Using the orthotopic murine tumour model B16/BL6 melanoma, the small contrast agent GdDOTA (DOTAREM®; Guerbet, Paris) was applied to assess the vascular transfer constant, Ktrans, and interstitial leakage space, whereas intravascular iron oxide nanoparticles (Endorem®; Guerbet, Paris) were used to detect relative tumour blood volume (rTBV), and in one experiment blood flow index (BFI). No correlations were observed between these four parameters (r2 always <0.05). The B16/BL6 primary tumour and lymph‐node cervical (neck) metastases produced high levels of the permeability/growth factor, VEGF. To probe the model, the novel VEGF receptor (VEGF‐R) tyrosine kinase inhibitor, PTK787/ZK222584 (PTK/ZK) was tested for anti‐tumour efficacy and its effects on DCE‐MRI measured parameters of tumour vascularity. Data from the non‐invasive measure of tumour vascularity were compared with a histological measurement of vasculature using the DNA‐staining dye H33342. PTK/ZK inhibited growth of the primary and, particularly, cervical tumour metastases following chronic treatment for 2 weeks (50 or 100 mg/kg daily) of 1‐week‐old tumours, or with 1 week of treatment against more established (2‐week‐old) tumours. After chronic treatment with PTK/ZK, DCE‐MRI detected significant decreases in Ktrans and interstitial leakage space, but not rTBV of both primary tumours and cervical metastases. Histological data at this time‐point showed a significant decrease in blood vessel density of the cervical metastases but not the primary tumours. However, in the cervical metastases, the mean blood vessel width was increased by 38%, suggesting overall no marked change in blood volume. After acute (2–4 day) treatment, DCE‐MRI of the cervical metastases demonstrated a significant decrease in Ktrans and interstitial leakage space and also in the initial area under the enhancement curve for GdDOTA (IAUC), but no change in the rTBV or BFI. Thus, significant changes could be detected in the DCE‐MRI measurement of tumour uptake of a small contrast agent prior to changes in tumour size, which suggests that DCE‐MRI could be applied in the clinic as a rapid and sensitive biomarker for the effects of VEGF‐R inhibition on tumour blood vessel permeability and thus may provide an early marker for eventual tumour response. Copyright © 2005 John Wiley & Sons, Ltd.
Vulcanization characteristics and mechanical properties of nitrile rubber filled with short leather fibres
Authors: Natchimuthu N. , Radhakrishnan Ganga , Palanivel K. , Ramamurthy K. , Anand J. S. 
Published: May 2005

AbstractLeather shavings have been used as filler in short fibre form for nitrile rubber reinforcement. Shavings neutralized with sodium bicarbonate and ammonia showed improved vulcanization characteristics and mechanical properties, whereas sodium hydroxide neutralized shavings exhibited poor properties. Swelling of the vulcanizates in water and 1% NaOH was found to increase with leather loading, whereas in MEK a reversed trend was observed. Thermogravimetric analysis indicates that the thermal stabilities of the vulcanizates fall between those of pure leather and gum nitrile rubber vulcanizate.
On the nature of intermolecular interactions in polymer blends. Use of model compounds as a tool for investigating polymer–polymer miscibility
Authors: Ruggeri Giacomo , Bertani Roberto , Aglietto Mauro , D'Alessio Aldo , Benedetti Enzo 
Published: May 2005

AbstractAn FTIR study has been performed on two low molecular weight model compounds of diethylmaleate functionalized polyethylene, ethyl 3‐carbethoxy‐4‐propylheptanoate (EPH) and ethyl 3‐carbethoxy‐4‐hexyldecanoate (EHD), recording spectra in different solvents (heptane, tetrahydrofuran, carbon tetrachloride, chloroform) and in the presence of a presumable PVC model, 2‐chlorobutane (2CB). These different systems allowed the observation of some correlations between spectroscopic data and chemical composition of solutions and functionalized polyethylene/PVC blends, supporting the hypothesis of specific hydrogen bond type interactions between the carboxylic oxygen of the functionalized polyethylene and the methinic hydrogens of PVC.
Thermodynamic state of reinforced interpenetrating polymer networks
Authors: Lipatov Yuri S. , Karabanova Ludmila V. , Sergeeva Ludmila M. 
Published: May 2005

AbstractThe free energies of mixing of two networks in the interpenetrating polymer network based on crosslinked polyurethane and poly(ester acrylate) have been determined by the vapour sorption method. It was established that the constituent networks in the IPN are not miscible.The introduction of fillers of different chemical nature increases the compatibility. The thermodynamic affinity of the fillers to the individual networks and IPN was estimated. It was established that when the free energy of interaction of one or both components of the IPN with the filler is negative, reinforcement leads to the formation of a compatible and equilibrium system. For fillers having no affinity to the polymers, compatibilization is observed, which is connected with slowing down of phase separation in the system in the presence of filler.
Synthesis and properties of polydiacetylene‐containing polyesters
Authors: Lovell P. A. , Stanford J. L. , Wang Y‐F. , Young R. J. 
Published: May 2005

AbstractA series of diacetylene‐containing polyesters with number‐average molar masses (GPC) in the range 900–4200 g mol−1 were prepared from terephthaloyl chloride and hexa‐2,4‐diyne‐1,6‐diol using benzoyl chloride as a monofunctional reactant for control of molar mass. Degrees of crystallinity were estimated from WAXD to be up to 29%. Correlations between molar mass, melting behaviour, degree of crystallinity and thermal cross‐polymerisation of diacetylene‐containing polyesters have been established using hot‐stage microscopy, DSC and resonance Raman spectroscopy. The polyester with M̄n of 1264 g mol−1 gave the best balance between processability and the ability to cross‐polymerise efficiently. Its degree of crystallinity before cross‐polymerisation was estimated from WAXD measurments to be 24%, a value coincident with the percentage conversion of diacetylene units to polydiacetylene chains measured by 13C solid‐state NMR. The optimum conditions for compression moulding the polyester to produce a material with a strong Raman spectrum involved heating under vacuum at 120°C for 6h after an initial 3 h heat‐up period. The material thus produced gave an intense Raman CC stretching band, which upon tensile deformation shifted linearly with strain to lower wavenumber by 12.0 cm−1 %−1. The potential use of the diacetylene‐containing polyesters in the preparation of model blends for use in quantitative micromechanics studies of stress transfer between phases is briefly discussed.
FTIR spectroscopic characterization of hydrogenated polyoctenamer and polynorbornene and DSC study of their thermal properties
Authors: Cataldo Franco 
Published: May 2005

AbstractDiimide‐hydrogenated polyoctenamer and polynorbornene have been characterized by FT‐infrared spectroscopy and differential scanning calorimetry (DSC). Hydrogenated polyoctenamer has been studied in comparison with hydrogenated polybutadiene and polyethylene. A crystallinity ranging from 71% to 77% was found, while the melting point of hydrogenated polyoctenamer was found to be in the range 127–129°C. Hydrogenated polyoctenamer as well as hydrogenated polybutadiene resemble high density polyethylene (HDPE). Polynorbornene, which is completely amorphous, after hydrogenation shows a certain degree of crystallinity and a melting point of 140.8°C.
Synthesis and transacylating activity of isomeric Co(III)‐cyclodextrin artificial metalloenzymes
Authors: Akkaya Engin U. , Czarnik Anthony W. 
Published: May 2005

AbstractAlthough the cyclen – Co(III) complex has exhibited amongst the greatest rate accelerations in acyl and phosphoryl transfer reactions, this catalytic unit has not been used previously in the design of an artificial metalloenzyme. For this study, β‐cyclodextrin derivatives of cyclen – Co(III) with attachments to the primary and secondary sides of the cyclodextrin torus were synthesized. The primary‐side cyclodextrin‐cyclen‐Co(III) conjugate accelerates the hydrolysis of p‐nitrophenylacetate by a factor of 1000 (pH 7.0, 25°C) in comparison with the water‐catalyzed reaction. Maximum reactivity occurs at pH 7, consistent with the known pKa values and hypothesised mechanism of action of Co(III) complexes. The secondary‐side cyclodextrin‐cyclen‐Co(III) conjugate is less reactive towards p‐nitrophenylacetate hydrolysis under saturating conditions. Reactivities towards an azide, a phosphonate and a phosphate triester were in each case less than five times greater than the buffer‐catalyzed rate.
Polymerization and copolymerization of β‐butyrolactone and benzyl‐β‐malolactonate by aluminoxane catalysts
Authors: Benvenuti Manuela , Lenz Robert W. 
Published: May 2005

AbstractHigh molecular weight poly‐β‐hydroxybutyrate (PHB) and poly (β‐hydroxybutyrate‐co‐β‐benzyl malate) [P (HBBM)], were prepared by ring‐opening polymerization reactions of racemic β‐butyrolactone (BL) and racemic β‐benzyl malolactonate (BM) using two types of oligomeric aluminoxane catalysts prepared by the reaction of water with either triethyl‐aluminum (EAO) or triisobutylaluminum (IBAO). The stereoregularities, crystallinities, and molecular weights were determined for both the PHB homopolymers and the P (HBBM) copolymers by nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). All homopolymers and copolymers obtained could be separated into acetone‐soluble and acetone‐insoluble fractions. In every case the latter had higher degrees of crystallinity, higher molecular weights and higher degrees of stereoregularity (84–87% isotactic dyads) than the former. Hence all of the polymers obtained from both types of catalysts apparently had stereoblock isotactic structures. Copolymer compositions and monomer dyad sequence distributions were determined by NMR spectroscopy.
The synthesis of soluble, substituted silane high polymers by Wurtz coupling techniques
Authors: Miller R. D. , Thompson D. , Sooriyakumaran R. , Fickes G. N. 
Published: May 2005

AbstractThe Wurtz‐type coupling of a number of representative classes of substituted dichlorosilane monomers was investigated in considerable detail. Low temperature polymerization techniques, including ultrasonic activation, were also studied. Similarly, the effect of dipolar additives on the polymerization process was examined. The conclusions drawn from these studies provide some insight into the selection of useful polymerization conditions for the conversion of various monomer types into linear high polymers.
Dimethyl 1‐hexene‐2,5‐dicarboxylate, methyl methacrylate dimer, as polymerizable acrylic ester bearing bulky α‐substituent
Authors: Otsu Takayuki , Yamada Bunichiro , Fujita Mitsuo , Okuo Masami 
Published: May 2005

AbstractDimethyl 1‐hexene‐2,5‐dicarboxylate (MMAD), a methyl methacrylate dimer, which is an acrylic ester bearing a large α‐substituent, was polymerized and copolymerized. During the bulk polymerization at room temperature, an ESR spectrum assigned to the propagating radical was observed. MMAD which polymerized much slower than methyl methacrylate (MMA) was less reactive in copolymerization than MMA. These findings may exemplify that slow propagation concomitant with termination suppressed with steric hindrance could lead to polymer formation of MMAD. Thermogravimetric analysis of poly(MMAD) exhibited that the degadation through depropagation was facilitated by the α‐substituent. A relatively large chain transfer constant of MMAD in MMA polymerization, 9.8 × 10−3, was evaluated consistent with a considerable decrease in the molecular weight of poly (MMA) in the presence of a small amount of MMAD.
Photooxidation of blends of polystyrene and poly (vinyl methyl ether)
Authors: Chien Y. Y. , Pearce Eli M. , Kwei T. K. 
Published: May 2005

AbstractPhotooxidation of blends of polystyrene and poly (vinyl methyl ether) was studied at 30°C. The oxygen uptake by PS was negligible but PVME oxidized readily. The induction period of oxidation of PVME was prolonged by the presence of PS. The steady state rate of oxidation of the blend was strongly influenced by the segmental mobility of the blend which also governed the kinetics and morphology of phase separation. The molecular weight of PVME decreased more slowly in the blend as PS content increased. It was believed that the reaction between PVME radicals and PS resulted in less reactive PS radicals which retarded oxidation. The PS radicals eventually underwent chain scission reactions.
Essential work of fracture and j‐integral measurements for ductile polymers
Authors: Mai Yiu‐Wing , Powell Peter 
Published: May 2005

AbstractIn the ductile tearing of polymers that neck before failure it is shown that the specific essential fracture work (we), consisting of the energies dissipated in forming and tearing the neck, is a material property for a given sheet thickness and is independent of specimen geometry. Work of fracture experiments using both double deep‐edge notched (DENT) and deep‐center notched tension (DCNT) geometries with different ligament lengths yielded almost identical we values for a grade of high‐density polyethylene. These measurements for we are in fairly good agreement with the theoretical values based on the J integral evaluated along a contour surrounding the neck region near the crack tip. Under J‐controlled crack growth conditions, it is shown that Jc obtained by extrapolation of the JR curve to zero crack growth and the slope dJ/da are identical, respectively, to we and 4βwp obtained from the straight line relationship between the specific total work of fracture (wf) and ligament length (l).
Deformation mechanisms in biaxially drawn polyethylene
Authors: Gerrits Nicolé S. J. A. , Young Robert J. 
Published: May 2005

AbstractThe crystal orientation of solid‐state biaxially drawn solution‐crystallized ultra‐high‐molecular weight polyethylene (UHMW‐PE) film has been revealed from flat‐plate wide‐angle x‐ray scattering (WAXS) patterns and interpreted in terms of crystal plasticity. A slightly drawn film (λ ≤ 3 × 3) possesses only a (100) planar orientation, whereas in a highly drawn film (λ ≥ 6 × 6), a mixed (100) and {110} planar orientation is present. Crystal deformation is found to proceed both by slip on (100) and {110} planes, resulting in a (100) texture in a similar way to crystal deformation in uniaxially drawn polyethylene and by {110} 〈110〉 transverse slip and/or {310} twinning which results in a {110} texture. It is postulated that during transverse slip or twinning, the molecules deform without chain extension. As a consequence, neither the molecular draw ratio nor the tensile properties change significantly for macroscopic draw ratios above 10 in contrast to the data obtained for uniaxially drawn polyethylene.
A Study of the Physical Significance of Three‐Dimensional signature waveforms
Authors: Kaye Brian H. , Leblanc John E. , Clark Garry G. 
Published: May 2005

AbstractIt has been shown that the projected area of a rotating fineparticle can be used to construct a signature waveform which is descriptive of some aspects of the three‐dimensional morphology of a fineparticle. If the fineparticle is rotated systematically about two mutually independent axes, through two sets of 90 degrees rotations, the signature waveform can be related to the surface area of the convex hull. It could be that the convex hull of a fineparticle is related to its fluid dynamic behaviour and its ability to modify the effective viscosity of a fluid in its suspension. This type of significance of different types of Cauchy signature waveforms are discussed. The concept of three‐dimensional signature waveforms is extended to cover the structural shape waveform and the fractal waveforms which, respectively, describe the spatial structure and the ruggedness of a fineparticle profile. The possible utilization of all three types of waveforms to describe in a complete manner the three‐dimensional structure of a rugged fineparticle is discussed.
Calibration of Optical Particle Counters with Respect to Particle Size
Authors: Fissan Heinz , Helsper Christoph , Kasper Wolfgang 
Published: May 2005

AbstractIn optical particle counters the calibration function describing the relationship between the amplitude of the scattered light pulses and particle size depends on several parameters. In this paper, several calibration methods are discussed. As an example, the calibration of an optical particle counter (HC‐15, Polytec GmbH & Co., Waldbronn, FRG) is demonstrated, using real aerosols with unknown particle shape and refractive index, and a precollector with known collection efficiency. The error analysis, when performed together with the results of an indirect check of the obtained calibration curve, provide evidence that this method yields good calibration curves for the aerosol being measured. The method is then applied to obtain the calibration curves for quartz dust, ash from a fluidized bed combustor and coal dust.
A Special Feeder for Diffraction Pattern Analysis of Dry Powders
Authors: Leschonski Kurt , Rüthele Stephan , Menzel Ulrich 
Published: May 2005

AbstractNumerous unit operations in particle technology require that dry powders are fed into a system with as little fluctuation as possible in flow rate and velocity and that the powder is dispersed in flowing air. A feeding and dispersing system has been developed which allows mass throughputs between 0.1 and 20 kg/h. It has been used as a feeder unit for dry particle size analysis from diffraction patterns.
Measurement of Particle Size and Shape, some Reflections on the BCR reference material programme
Authors: Scarlett Brian 
Published: May 2005

AbstractThere are three basic philosophies which may be taken towards the problem of calibrating particle size measuring techniques. The first is to assume a model of the process and that the technique is thus absolute. The second is to calibrate an instrument using the particles which are to be measured themselves. In this paper, these three approaches are compared and contrasted. As an example, the programme of certification of the BCR samples is cited and discussed. The paper then advocates the use of the equivalent volume diameter as the basic particle size characterization and its combination with other measurements as shape determinations. The representation of both size and shape in this way is conveniently presented in the form of orthogonal diagrams.
Measurement of Particle Size Distributions in Gas Flows with an Optical particle counter
Authors: Büttner Helmut 
Published: May 2005

AbstractIn order to characterize flow separation and classification processes, particle size distributions must be measured in the airborne state without affecting the state of dispersion or disturbing the flow. Light scattering devices with an optically defined measuring volume are specially designed for this purpose. However the light scattering device must be calibrated using non‐ideal particles which are present within the multiphase flow, preferably on an equivalent diameter based on settling rate. Such a calibration can be achieved by measuring with an optical particle counter before and after an impactor in droplet systems and a sampling cyclone in systems of solid particles. By measuring the calibration curves the size distribution of the investigated particles are also determined. This measuring technique allows the best use of the optical particle counter in industrially relevant cases which may have high particle concentrations, wide distributions, non‐ideal particles and an undefined state of dispersion.