bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics and mechanism of the reactions of platinum(II)‐dipicolinate and platinum(II)‐glycylglycine with oxalate ion
Authors: Dey Sukalpa , Banerjee Pradyot 
Published: May 2003

AbstractThe kinetics of the reactions of [Pt(dipic)(H2O)] and [Pt(digly)(H2O)] (where H2dipic = pyridine‐2,6‐dicarboxylic acid and H2digly = glycylglycine) with oxalate ion were studied at 25°C in aqueous medium by UV–vis spectroscopy at I = 0.1 mol dm−3 over an wide range of pH. A probable associative pathway may involve a five‐coordinate intermediate leading to the formation of an unidentate oxalate species, which converts to bidentate chelate in subsequent fast steps. The products are isolated and characterized by CHN analysis, IR, and 1H NMR spectra. The kinetic data from pH variation experiments are fitted by a computer program to a sequence of reactions and the different rate constants are evaluated. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 327–333, 2003
Rate coefficients and mechanisms of the reaction of cl‐atoms with a series of unsaturated hydrocarbons under atmospheric conditions
Authors: Orlando John J. , Tyndall Geoffrey S. , Apel Eric C. , Riemer Daniel D. , Paulson Suzanne E. 
Published: May 2003

AbstractRate coefficients and/or mechanistic information are provided for the reaction of Cl‐atoms with a number of unsaturated species, including isoprene, methacrolein (MACR), methyl vinyl ketone (MVK), 1,3‐butadiene, trans‐2‐butene, and 1‐butene. The following Cl‐atom rate coefficients were obtained at 298 K near 1 atm total pressure: k(isoprene) = (4.3 ± 0.6) × 10−10cm3 molecule−1 s−1 (independent of pressure from 6.2 to 760 Torr); k(MVK) = (2.2 ± 0.3) × 10−10 cm3 molecule−1 s−1; k(MACR) = (2.4 ± 0.3) × 10−10 cm3 molecule−1 s−1; k(trans‐2‐butene) = (4.0 ± 0.5) × 10−10 cm3 molecule−1 s−1; k(1‐butene) = (3.0 ± 0.4) × 10−10 cm3 molecule−1 s−1. Products observed in the Cl‐atom‐initiated oxidation of the unsaturated species at 298 K in 1 atm air are as follows (with % molar yields in parentheses): CH2O (9.5 ± 1.0%), HCOCl (5.1 ± 0.7%), and 1‐chloro‐3‐methyl‐3‐buten‐2‐one (CMBO, not quantified) from isoprene; chloroacetaldehyde (75 ± 8%), CO2 (58 ± 5%), CH2O (47 ± 7%), CH3OH (8%), HCOCl (7 ± 1%), and peracetic acid (6%) from MVK; CO (52 ± 4%), chloroacetone (42 ± 5%), CO2 (23 ± 2%), CH2O (18 ± 2%), and HCOCl (5%) from MACR; CH2O (7 ± 1%), HCOCl (3%), acrolein (≈3%), and 4‐chlorocrotonaldehyde (CCA, not quantified) from 1,3‐butadiene; CH3CHO (22 ± 3%), CO2 (13 ± 2%), 3‐chloro‐2‐butanone (13 ± 4%), CH2O (7.6 ± 1.1%), and CH3OH (1.8 ± 0.6%) from trans‐2‐butene; and chloroacetaldehyde (20 ± 3%), CH2O (7 ± 1%), CO2 (4 ± 1%), and HCOCl (4 ± 1%) from 1‐butene. Product yields from both trans‐2‐butene and 1‐butene were found to be O2‐dependent. In the case of trans‐2‐butene, the observed O2‐dependence is the result of a competition between unimolecular decomposition of the CH3CH(Cl)CH(O•)CH3 radical and its reaction with O2, with kdecomp/kO2 = (1.6 ± 0.4) × 1019 molecule cm−3. The activation energy for decomposition is estimated at 11.5 ± 1.5 kcal mol−1. The variation of the product yields with O2 in the case of 1‐butene results from similar competitive reaction pathways for the two β‐chlorobutoxy radicals involved in the oxidation, ClCH2CH(O•)CH2CH3 and •OCH2CHClCH2CH3. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 334–353, 2003
Isomeric hexyl‐ketohydroperoxides formed by reactions of hexoxy and hexylperoxy radicals in oxygen
Authors: Jorand François , Heiss Adolphe , Perrin Olivier , Sahetchian Krikor , Kerhoas Lucien , Einhorn Jacques 
Published: May 2003

AbstractIsomerization reactions of peroxy radicals during oxidation of long‐chain hydrocarbons yield hydroperoxides, and therefore play an important role in combustion and atmospheric chemistry, because of their action as branching agents in these chain reaction processes. Different formation mechanisms and structures are involved. Three isomeric hexyl‐ketohydroperoxides are formed via isomerization reactions in oxygen of either hexoxy RO or hexylperoxy RO2 radicals. In the temperature range 373–473 K, 2‐hexoxy (C6H13O) radical in O2/N2 mixtures gives 2‐hexanone‐5‐hydroperoxide via two consecutive isomerizations. The second one is a H transfer from a HC(OH) group occurring via a seven‐membered ring intermediate:

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Its rate constant has been determined at 453 and 483 K, and the general expression can be written as

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Hexylperoxy C6H13O2 radical, present in n‐hexane oxidation by oxygen/nitrogen mixtures in the temperature range 543–573 K, gives 2‐hexanone‐4‐hydroperoxide, 3‐hexanone‐5‐hydroperoxide, and 2‐hexanone‐5‐hydroperoxide. The first two are formed through an isomerization reaction via a six‐membered ring intermediate, and the last through an isomerization reaction via a seven‐membered ring intermediate. The ratio of the rate constant of the isomerization reactions of RO2 radicals via a seven‐membered ring intermediate to that via a six‐membered ring is found to be 0.795, and the rate constant expression via a seven‐membered ring intermediate is proposed:

equation image

The role of these reactions in the formation of radicals in the troposphere is discussed.Other products arising in the reactional path, such as ketones, furans, and diketones, are identified.Identification of these ketohydroperoxides was made using gas chromatography/mass spectrometry with electron impact, and with NH3 (or ND3) chemical ionization. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 354–366, 2003
The H+NO recombination reaction over a wide temperature range
Authors: Riley Patrick S. , Cosic Biljana , Fontijn Arthurxy 
Published: May 2003

AbstractRate coefficients of the title reaction have been measured in a high‐temperature photochemistry (HTP) reactor using Ar as the bath gas. H atoms were generated by flash photolysis of NH3 and their relative concentrations were monitored by resonance fluorescence. The data are best fitted by k(295–905 K) = 6.5 × 10−34 (T/K)0.206 exp(780K T) cm6 molecule−2 s−1, with ±2σ precision values varying from 16 to 36% and corresponding suggested accuracy levels of 29–42%. Using a literature value for the relative collision efficiencies of N2 and Ar indicates that for N2 as the third body the above rate coefficient expression should be multiplied by 1.6. This leads to good agreement with two recent near 1000 K measurements. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 374–380, 2003
A shock tube, laser‐schlieren study of the pyrolysis of isobutene: Relaxation, incubation, and dissociation rates
Authors: Santhanam S. , Kiefer J. H. , Tranter R. S. , Srinivasan N. K. 
Published: May 2003

AbstractDissociation, vibrational relaxation, and unimolecular incubation have all been observed in shock waves in isobutene with the laser‐schlieren technique. Experiments covered a wide range of high‐temperature conditions: 900–2300 K, and post‐incident shock pressures from 7 to 400 torr in 2, 5, and 10% mixtures with krypton. The surprising observation is that of vibrational relaxation, well resolved over the full temperature range. The resolved process is completely exponential, with relaxation times in the range 20–120 ns atm. Relaxation and dissociation are clearly separated for T > 1850 K, with estimated incubation times near 200 ns atm. Incubation is essential for modeling of the very low‐pressure decomposition. Modeling of gradients with a chain mechanism initiated by CH fission produces an excellent fit and accurate dissociation rates that show severe falloff. A restricted‐rotor, Gorin‐model RRKM analysis fits these rates quite well with the known bond‐energy as barrier and 〈ΔE〉down = 680 cm−1. The extrapolated k∞ is log k∞(s−1) = 19.187–0.865 log T −87.337 (kcal/mol)/RT, in good agreement with previous work. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 381–390, 2003
Estimates of hyperbolic equations in Hardy spaces
Authors: Chang Der–Chen , Lee Yong–Seok 
Published: June 2003

AbstractThe aim of this paper is to study estimates of hyperbolic equations in Hardy classes. Consider the Cauchy problem P(Dt,Dx)u(t, x) = 0 for x ∈ ℝd and t > 0 with the initial conditions Djtu(0, x) = gj (x), j = 0, 1, …, m – 1. We assume that the symbol 𝒫(τ, ξ) of P(Dt,Dx) can be factorized as 𝒫(τ, ξ) = $ \prod ^{m}_{j=1} $(τ–ϕj(ξ)) where ϕj (ξ) = $ \left( \xi ^{2n_{j}}_{1} + \ldots + \xi ^{2n_{j}}_{d} \right)^{{1\over {2n_{j}}}} $, j = 1, …, m. We assume further that gj ∈ Hpk (ℝd) for j = 1, …, m – 1. Then the solution u of the problem (3.13) is in Hp(ℝd) provided k ≥ (d– 1) $ \left\vert {1 \over p} - {1 \over 2}\right\vert $ and $ {{2n-2} \over {2n-1}} $ < p < ∞. Here n = max{n1, …, nm}. In particular, P(Dt, Dx)u = $ {{\partial ^2 u} \over {\partial t^2}} $ – Δu = 0 with u(0, x) = f(x) and $ {{\partial u} \over {\partial t}} $ (0, x) = g(x), then the solution u of the wave equation is in Hp(ℝd) provided k ≥ (d – 1) $ \left\vert {1 \over p} - {1 \over 2}\right\vert $ and 0 < p < ∞.
Geodesic graphs on the 13–dimensional group of Heisenberg type
Authors: Dušek Z. , Kowalski O. 
Published: June 2003

AbstractA g.o. space is a homogeneous Riemannian manifold M = (G/H, g) on which every geodesic is an orbit of a one–parameter subgroup of the group G. (G acts transitively on M as a group of isometries.) Each g.o. space gives rise to certain rational maps called “geodesic graphs”. We are particularly interested in the case when the geodesic graphs are of nonlinear character.Up to recently only linear geodesic graphs and nonlinear geodesic graphs of degree two were observed. Here we study the generalized Heisenberg group (in the sense of A. Kaplan) of dimension 13 and with 5–dimensional center. We show that this is a g.o. space for which the lowest degree of a geodesic graph is equal to six or three, depending on the choice of the isometry group G.
Log–canonical forms and log canonical singularities
Authors: Flenner Hubert , Zaidenberg Mikhail 
Published: June 2003

AbstractFor a normal subvarietyVof ℂnwith a good ℂ*–action we give a simple characterization for when it has only log canonical, log terminal or rational singularities. Moreover we are able to give formulas for the plurigenera of isolated singular points of such varieties and of the logarithmic Kodaira dimension ofV\{0}. For this purpose we introduce sheaves ofm–canonical andL2,m–canonical forms on normal complex spaces. For the case of affine varieties with good C*–action we give an explicit formula for these sheaves in terms of the grading of the dualizing sheaf and its tensor powers.
A geometric description of the neutral component of the Jacobian of a real plane curve having many pseudo–lines
Authors: Fichou G. , Huisman J. 
Published: June 2003

AbstractA pseudo–line of a real plane curve is a real branch that is not homologically trivial in ℙ2(ℝ). A real plane curve C of degree d is said to have many pseudo–lines if it has exactly d – 2 pseudo–lines and if the genus of its normalization C̃ is equal to d – 2. Let C be such a curve. We give a planar description of the neutral component of the set of real points of the Jacobian of the normalization C̃ of C.
Non nuclear integral operators with continuous kernels
Authors: Frerick Leonhard 
Published: June 2003

AbstractIn this note we give a positive answer to the following question posed by A. Pietsch:Is there for all p, q ∈ (1, ∞) a continuous kernel K such that the associated integral operator TK : Lq([0, 1]) → Lp([0, 1]) fails to be nuclear?
The counting function for a λ–rational Sturm–Liouville problem
Authors: Greenberg Leon , Marletta Marco 
Published: June 2003

AbstractWe develop an oscillation theory for an equation of Hain–Lüst type, valid both outside and inside the essential spectrum. The results proved allow us to locate eigenvalues in the essential spectrum or resonances close to the essential spectrum. The numerical implementation of the oscillation theory requires a regularizing transformation of Niessen and Zettl.
Simple criterions for strongly starlikeness and starlikeness of certain order
Authors: Hamada Hidetaka , Kohr Gabriela 
Published: June 2003

AbstractIn this paper, we will give a sufficient condition for locally univalent holomorphic functions on the unit disc . in C to be strongly starlike. Also, we will give sufficient conditions for locally biholomorphic mappings on the unit ball B in a complex Banach space X to be starlike of certain order or strongly starlike.
Role of the somatosensory system in primary dystonia
Authors: Tinazzi Michele , Rosso Tiziana , Fiaschi Antonio 
Published: May 2003

AbstractThe pathophysiology of dystonia is still not fully understood, but it is widely held that a dysfunction of the corticostriatal–thalamocortical motor circuits plays a major role in the pathophysiology of this syndrome. Although the most dramatic symptoms in dystonia seem to be motor in nature, marked somatosensory perceptual deficits are also present in this disease. In addition, several lines of evidence, including neurophysiological, neuroimaging and experimental findings, suggest that both motor and somatosensory functions may be defective in dystonia. Consequently, abnormal processing of the somatosensory input in the central nervous system may lead to inefficient sensorimotor integration, thus contributing substantially to the generation of dystonic movements. Whether somatosensory abnormalities are capable of triggering dystonia is an issue warranting further study. Although it seems unlikely that abnormal somatosensory input is the only drive to dystonia, it might be more correlated to the development of focal hand than generalized dystonia because local somesthetic factors are more selectively involved in the former than in the latter where, instead it seems to be a widespread deficit in processing sensory stimuli of different modality. Because basal ganglia and motor areas are heavily connected not only with somatosensory areas, but also with visual and acoustic areas, it is possible that abnormalities of other sensory modalities, such as visual and acoustic, may also be implicated in the pathophysiology of more severe forms of primary dystonia. Further studies have to be addressed to the assessment of the role of sensory modalities and their interaction on the pathophysiology of different forms of primary dystonia. © 2003 Movement Disorder Society
Unilateral subthalamic deep brain stimulation in advanced Parkinson's disease
Authors: Linazasoro Gurutz , Van Blercom Nadège , Lasa Asier 
Published: May 2003

AbstractEight patients with advanced PD received a unilateral STN DBS. The UPDRS III off drug–on DBS was improved by a mean 44%. Dyskinesias were ameliorated. Levodopa daily dose was reduced. Three patients required the implantation of the second electrode. Unilateral DBS may be efficacious in some patients with advanced PD. © 2003 Movement Disorder Society
Unusual phenotypes in DYT1 dystonia: A report of five cases and a review of the literature
Authors: Edwards Mark , Wood Nicholas , Bhatia Kailash 
Published: May 2003

AbstractSince the advent of widespread testing for the presence of the DYT1 gene mutation, the range of phenotypes that have been associated with this genetic abnormality has expanded. We report on 5 DYT1 gene‐positive patients with unusual phenotypes. Two of them had late presentation, one of these after peripheral injury. Three additional patients had late progression of symptoms, onset after exposure to haloperidol, and severe bulbar involvement, respectively. The clinical heterogeneity of this condition raises problems for clinicians in selecting appropriate patients for diagnostic testing. Also, because of the low phenotypic penetrance of DYT1 dystonia, the discovery of the DYT1 mutation in a patient with an atypical clinical syndrome may not necessarily suggest a causal relationship. We have, therefore, analysed all published clinical studies of DYT1 dystonia to guide clinical decision making concerning DYT1 gene testing based on current information. © 2003 Movement Disorder Society
Neuropsychiatric interpretations of postencephalitic movement disorders
Authors: Ward Christopher D. 
Published: May 2003

AbstractThis study reviews the impact of encephalitis lethargica (EL) on concepts of behaviour and movement during the 1920s and 1930s. Clinicopathological correlations were imprecise but supported the role of subcortical structures in complex patterns of motor behaviour. This possibility challenged the widely assumed hegemony of the cerebral cortex. There was a perceived link between involuntary movements and reduced impulse control and also between parkinsonism and a defect in volition. Contemporary observers interpreted postencephalitic phenomena such as oculogyria in psychodynamic as well as in neurophysiological terms. EL also gave some support to the idea that neuroses such as obsessional neurosis and hysteria might have an organic basis. These speculations recently have acquired more credibility. The large amount of literature on EL and its sequelae could perhaps make further contributions to understanding the pathology of voluntary movement and action. © 2003 Movement Disorder Society
Does ageing have an effect on midbrain premotor nuclei for vertical eye movements?
Authors: Henson Craig , Staunton Hugh , Brett Francesca M. 
Published: May 2003

AbstractCurrently, there is debate in the clinical literature as to whether defects in vertical gaze are a consequence of normal ageing or a component of an underlying neurodegenerative disorder. Although pathological changes have been demonstrated in diseased subjects, no study to date has addressed the question of normal ageing effects. In this retrospective study, we examined 23 neurologically and pathologically normal subjects (age 18–91). Using an unbiased, frame‐based sampling method, we quantified neuronal and glial cell densities in 10 young (<50) and 13 aged (>65) subjects in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), the key premotor substrate in the vertical gaze pathway. We found no statistically significant difference in neuronal density, glial cell density, or neuron‐to‐glial cell ratios between the young and the aged. We conclude, therefore, that neuronal loss, neuronal atrophy, or gliosis in the riMLF are not consequences of normal ageing. © 2003 Movement Disorder Society
Brain perfusion SPECT in patients with corticobasal degeneration: Analysis using statistical parametric mapping
Authors: Hossain A.K.M. Moinul , Murata Yuji , Zhang Lin , Taura Shin‐ichi , Saitoh Yukinobu , Mizusawa Hidehiro , Oda Kenji , Matsushima Eisuke , Okubo Yoshiro , Shibuya Hitoshi 
Published: May 2003

AbstractWe sought to determine the characteristics of brain perfusion in patients with corticobasal degeneration (CBD) using single photon emission computed tomography (SPECT) and statistical parametric mapping (SPM). Thirteen patients with CBD and 10 age‐matched healthy volunteers were examined using brain perfusion SPECT and 99mTc‐ethyl cysteinate dimer (ECD). Regional cerebral blood flow (rCBF) measurements were performed noninvasively using a graphic analysis method. Both the absolute rCBF data (raw data) and the adjusted rCBF data (global CBF normalized to 50 ml/100 g/min) were used in the SPM analysis. A significant decrease in the absolute rCBF was observed in extended areas of the brain in CBD patients compared to the control group. These areas included the frontal, parietal, and temporal cortices; basal ganglia; thalamus; and pontocerebellar regions. Our results suggest that the extent of the reduced rCBF region in CBD patients is more widespread than previously reported. © 2003 Movement Disorder Society
Abnormal cortical sensory activation in dystonia: An fMRI study
Authors: Butterworth Stephen , Francis Sue , Kelly Edward , McGlone Francis , Bowtell Richard , Sawle Guy V. 
Published: May 2003

AbstractDespite the obvious motor manifestations of focal dystonia, it is recognised that the sensory system plays an important role in this condition. This functional magnetic resonance imaging study examines the sensory representations of individual digits both within the subregions of the primary sensory cortex (SI) and in other nonprimary sensory areas. Patients with focal dystonia and controls were scanned during vibrotactile stimulation of both the index (digit 2) and little (digit 5) fingers of their dominant hand (which was the affected hand in all the dystonic subjects). The activation maps obtained were analysed for location, size, and magnitude of activation and three‐dimensional (3‐D) orientation of digit representations. Data from both groups were compared. There were significant differences in the average 3‐D separation between the two digit representations in area 1 of SI between subject groups (9.6 ± 1.2 mm for controls and 4.1 ± 0.2 mm for dystonic subjects). There were also strong trends for reversed ordering of the representation of the two digits in both the secondary sensory cortex and posterior parietal area between the two groups. In addition, in dystonic subjects, there was significant under activation in the secondary somatosensory cortex (SII/area 40) for both digits and in the posterior parietal area for digit 5. These results indicate the presence of widespread activation abnormalities in the cortical sensory system in dystonia. © 2003 Movement Disorder Society
Sleep attacks, daytime sleepiness, and dopamine agonists in Parkinson's disease
Authors: Paus Sebastian , Brecht Hans Michael , Köster Jürgen , Seeger Gert , Klockgether Thomas , Wüllner Ullrich 
Published: May 2003

AbstractTo study the putative association of dopamine agonists with sleep attacks in patients with Parkinson's disease (PD) and their relation to daytime sleepiness, we performed a survey of 2,952 PD patients in two German counties. In 177 patients, sudden, unexpected, and irresistible sleep episodes while engaged in some activity were identified in a structured telephone interview. Ninety‐one of these patients denied the occurrence of appropriate warning signs. A total of 133 patients (75%) had an Epworth Sleepiness Scale (ESS) score >10; 65 (37%) >15. Thirty‐one patients (18%) had an ESS score ≤10 and yet experienced sleep attacks without warning signs. Thus, although a significant proportion of patients at risk for sleep attacks might be identified using the ESS, roughly 1% of the PD patient population seems to be at risk for sleep attacks without appropriate warning signs and without accompanying daytime sleepiness. Sleep attacks occurred with all dopamine agonists marketed in Germany (α‐dihydroergocryptine, bromocriptine, cabergoline, lisuride, pergolide, pramipexole, ropinirole), and no significant difference between ergot and nonergot drugs was evident. Levodopa (L‐dopa) monotherapy carried the lowest risk for sleep attacks (2.9%; 95% confidence interval [CI], 1.7–4.0%) followed by dopamine agonist monotherapy (5.3%; 95% CI, 1.5–9.2%) and combination of L‐dopa and a dopamine agonist (7.3%; 95% CI, 6.1–8.5%). Neither selegeline nor amantadine or entacapone appeared to influence the occurrence of sleep attacks. A high ESS score, intake of dopamine agonists, and duration of PD were the main influencing factors for the occurrence of sleep attacks. The odds ratio for dopamine agonist therapy was 2.9 compared to 1.9 with L‐dopa therapy and 1.05 for a 1‐year‐longer disease duration. © 2003 Movement Disorder Society