bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of changes in head posture on the patterns of muscle activity in cervical dystonia (CD)
Authors: Buchman Aron S. , Comella Cynthia L. , Leurgans Sue , Stebbins Glenn T. , Goetz Christopher G.
Published: May 2005

Twelve patients with cervical dystonia (CD) and predominant rotation were studied to determine the effects of changes in head posture on the specific patterns of cervical muscle activity. Turns analysis was used to quantify muscle activity underlying head rotation, recorded simultaneously from the agonist and antagonist muscle pairs bilaterally (sternocleidomastoid [SCM] and splenius [SPL]). Muscle activity was compared between the uncompensated dystonic posture and during the maintenance of midposition. In addition, patients were separated into two groups (geste = 6; no geste = 6) based on whether they had a clinically efficacious geste to determine the effect of geste on patterns of cervical muscle activity. Muscle activity was measured during the maintenance of midposition with and without a clinical or simulated geste. Differences in muscle activity between the groups and postures were compared using repeated measure analysis of variance (ANOVA) analyses. The four muscles tested showed a significant difference in muscle activity in the uncompensated dystonic posture as a result of the increased activity in the agonist muscle pair (SCM and SPL responsible for the dystonic posture) (EMG amplitude: F[1,11] = 18.81, p = 0.0012; EMG frequency: F[1,11] = 32.07, p = 0.0001). Maintaining the head in the midposition was associated with a significant reduction in muscle activity compared with the uncompensated dystonic posture (EMG amplitude: F[1,9] = 6.36, p < 0.033; EMG frequency: F[1,9] = 10.96, p < 0.0091). This reduction in midposition muscle activity was significantly greater in the agonist muscle pair (EMG amplitude: F[1,10] = 19.70, p = 0.0013; EMG frequency: F[1,10] = 44.67, p < 0.0001). In the patients with clinically effective geste, there was no additional reduction in muscle activity observed in the midposition when they performed their geste (EMG amplitude: F[1,9] = 4.63, p = 0.060; EMG frequency: F[1,9] = 1.22, p = 0.298). These findings suggest that CD with rotation is characterized by predominantly increased agonist muscle activation. Patients with CD retain the ability to modulate this involuntary agonist muscle activity to maintain the head in the midposition. The maintenance of the midposition does not seem to be facilitated by geste.
Cerebral and cerebellar activation in correlation to the action‐induced dystonia in Writer's cramp
Authors: Odergren Tomas , Stone‐Elander Sharon , Ingvar Martin
Published: May 2005

The pattern of brain perfusion of four patients with writer's cramp and four control subjects were examined using positron emission tomography scans after [15O] butanol injections. Each subject was scanned 12 times to cover three repetitions of four different motor tasks with the right hand. Drawing of horizontal lines and variable durations of the writing of a prelearned text were performed in a pseudorandom order, the latter task commencing either simultaneously with or 30 sec or 120 sec before the tracer injection. The perceived difficulty and signs of dystonia progressed in correlation to the duration of writing. Statistical parametric maps were calculated to test hypotheses of regional specific effects dependent on the performed motor tasks. The patients with writer's cramp had progressively increased activity in the left primary sensorimotor and premotor cortices, the left thalamus, and the cerebellum with a right‐side predominance in correlation to the duration of writing. The regions with activity increases thus corresponded to a cerebrocerebellar motor circuit. The duration of writing correlated to a progressive reduction of activity in the patients'left supramarginal and angular gyri (Brodmann areas 40 and 39) and an inferior part of the left temporal lobe (area 20). The control subjects had neither a significant increase or decrease of activity in correlation to the duration of writing. Group‐specific differences were confirmed statistically in split‐plot interaction analyses.
Quantitative EEG analysis of depth electrode recordings from several brain regions of mutant hamsters with paroxysmal dystonia discloses frequency changes in the basal ganglia
Authors: Gernert Manuela , Richter Angelika , Rundfeldt Chris , Löscher Wolfgang
Published: May 2005

Computerized EEG spectral analyses of depth electrode recordings from striatum (caudate/putamen; CPu), globus pallidus (GP), and parietal cortex (pCtx) were performed before and after dystonic attacks in freely moving mutant dtsz hamsters with paroxysmal dystonia. In these hamsters, sustained attacks of abnormal movements and postures can be reproducibly induced by stress, such as placing the animals in a new environment. Data recorded from mutant hamsters were compared with recordings from age‐matched nondystonic control hamsters. The predominant EEG changes in CPu and GP of dystonic hamsters were significant decreases in the highfrequency β2 range and there was a tendency to increase in delta and theta activities. These changes were seen both before and after onset of dystonic attacks, indicating a permanent disturbance of neural activities in the basal ganglia of dystonic animals. No such changes were seen in the pCtx. Furthermore, no epileptic or epileptiform activity was seen in any of the recordings, substantiating a previous notion from cortical and hippocampal recordings that paroxysmal dystonia in these mutant hamsters has no epileptogenic basis. The present finding of abnormal synchronization of neural activity in the CPu and GP of dystonic hamsters adds to the belief that the striatopallidalthalamocortical circuit is the most likely site in which to search for the unknown defect in primary (idiopathic) dystonia. As suggested by this study, quantitative EEG analysis can increase the likelihood of detecting subtle EEG abnormalities in different types of idiopathic dystonia and thereby improves our understanding of the pathogenetic mechanisms of this movement disorder.
Cortical myoclonus in levodopa‐responsive parkinsonism
Authors: Caviness John N. , Adler Charles H. , Newman Stephanie , Caselli Richard J. , Muenter Manfred D.
Published: May 2005

We observed myoclonic movements of the fingers and wrists in two patients with a levodopa‐responsive parkinsonian syndrome most consistent with Parkinson's disease. These patients were studied with electrophysiological techniques. Brief (< 50 ms) myoclonic electromyographic discharges showed a time‐locked relationship to a focal premovement electroencephalographic potential. Somatosensoryevoked potentials were not enlarged and long‐latency reflexes were not grossly exaggerated. This pattern of electrophysiological findings can be distinguished from those previously found in other parkinsonian syndromes. These results provide evidence for a cortical origin of the myoclonus seen in these patients.
Treatment of restless leg syndrome with pergolide—an open clinical trial
Authors: Winkelmann Juliane , Wetter Thomas C. , Stiasny Karen , Oertel Wolfgang H. , Trenkwalder Claudia
Published: May 2005

Dopaminergic treatment with levodopa (L‐dopa) has been proven as the treatment of first choice in patients with restless leg syndrome (RLS). Augmentation of symptoms and end‐of‐dose rebound phenomena under L‐dopa/decarboxylase inhibitor treatment present major problems in some patients. To evaluate the efficacy of pergolide in RLS, we treated 15 patients suffering from severe RLS, who had previously experienced an augmentation of symptoms under long‐term treatment with L‐dopa, in an open clinical trial with pergolide. All patients reported an improvement of their RLS symptoms. Our study shows that pergolide, if administered at a mean dose of 0.4 mg in combination with domperidone, is a very effective drug in the treatment of sleep disturbances and daytime symptoms associated with RLS, and does not cause any serious side effects during the observation period of 6 months.
Case ascertainment uncertainties in prevalence surveys of Parkinson's disease
Authors: Anderson Dallas W. , Rocca Walter A. , De Rijk Maarten C. , Grigoletto Francesco , Melcon Mario O. , Breteler Monique M. B. , Maraganore Demetrius M.
Published: May 2005

Using unpublished data from five completed prevalence surveys of Parkinson's disease (PD), we investigated case ascertainment uncertainties that potentially have a direct effect on prevalence. These uncertainties arise from the choice of diagnostic criteria, the choice of screening method, and the amount of information lost because of nonresponse. The surveys were conducted in Argentina, India, China, Italy, and the Netherlands. Our analyses consisted of simple comparisons of prevalence results, positive predictive values (a screening measure), and nonresponse percentages. We found that (a) prevalence comparisons between surveys have diminished value if the surveys used different diagnostic criteria for PD; (b) screening performance may be affected adversely if symptom questions are answered by one family member for the entire family living together rather than by each family member individually; and (c) nonresponse from refusal or unavailability does not necessarily lead to bias, but special caution may be appropriate with prevalence results pertaining to elderly women.
A pilot evaluation of the tolerability, safety, and efficacy of tolcapone alone and in combination with oral selegiline in untreated Parkinson's disease patients
Authors: Hauser Robert A. , Molho Eric , Shale Heidi , Pedder Simon , Dorflinger Ernest E.
Published: May 2005

Tolcapone is a potent, reversible catechol‐O‐methyltransferase (COMT) inhibitor with both peripheral and central activity. It has been demonstrated to improve motor function and allow levodopa dose reductions in Parkinson's disease (PD) patients who are experiencing either a stable response or motor fluctuations while on levodopa/dopa decarboxylase inhibitor therapy. Because striatal dopamine is metabolized by COMT and monoamine oxidase (MAO), central COMT inhibition alone or in combination with MAO inhibition might provide symptomatic benefit for patients not receiving levodopa. We conducted a pilot study to evaluate the tolerability, safety, and efficacy of tolcapone alone and in combination with oral selegiline in early untreated PD patients. Patients were randomized to receive 200 mg tolcapone three times a day or placebo for the 8 weeks of the study. Open‐label oral selegiline (5 mg in the morning and midday) was administered to all patients during the second 4 weeks of the study. There was no difference between treatment groups according to the investigator's assessment of tolerability at week 4. Ninety‐five percent of tolcapone‐treated patients and 98% of placebo‐treated patients experienced excellent or good tolerability during the first 4 weeks (95% confidence interval [CI]: −10.3, 5.7; p = 0.57). A decrease in tolerability occurred in the tolcapone group during the second 4 weeks of the study following the addition of selegiline. The most commonly reported side effects were diarrhea (31% tolcapone, 7% placebo), nausea (21% tolcapone, 2% placebo), urine discoloration (12% tolcapone, 0% placebo), dizziness (12% tolcapone, 5% placebo), headaches (12% tolcapone, 10% placebo), and abdominal pain (10% tolcapone, 5% placebo). We did not identify symptomatic benefit associated with tolcapone alone or in combination with oral selegiline in this group of otherwise untreated PD patients.
Improvements in daily functioning after deep brain stimulation of the thalamus for intractable tremor
Authors: Lyons Kelly E. , Pahwa Rajesh , Busenbark Karen L. , Tröster Alexander I. , Wilkinson Steve , Koller William C.
Published: May 2005

Deep brain stimulation (DBS) of the thalamus reduces tremor in patients with essential tremor (ET). However, few studies have determined the degree of improvement in daily functioning associated with DBS. We developed a selfreport Tremor Activities of Daily Living Scale (TADLS) to compare daily functioning with the stimulator turned on and off. Patients rated their performance on the 30 items of the TADLS with the stimulator turned off and then on. They also performed 10 activities under the supervision of a clinician who rated their functional ability with stimulation off and then on. There was a 58% improvement in self‐rated TADLS scores in patients with DBS with the stimulator on compared with stimulation off. When activities were rated by the clinicain, the average improvement in functioning with the stimulator on was 54%. There were reasonably high correlations between patient and clinician ratings of functioning. ET patients have a marked improvement in daily functioning with thalamic DBS.
Young‐onset Parkinson's disease revisited—clinical features, natural history, and mortality
Authors: Schrag Anette , Ben‐Shlomo Yoav , Brown Richard , David Marsden C. , Quinn Niall
Published: May 2005

The authors report on clinical features and mortality rates in a group of 149 patients with apparent idiopathic parkinsonism starting before the age of 40 years. Ten had juvenile parkinsonism (JP; onset before age 21 years) and 139 had young‐onset Parkinson's disease (YOPD; onset at age 21 to 40 years). Included were 60 patients originally reported 10 years ago. Fifty percent of the JP group had a positive family history of parkinsonism in a first‐degree relative, and clinical presentation was heterogeneous. Mortality risk was threefold that of the normal population. In the YOPD group, the mortality risk was double that of the normal population. Poor initial response to L‐dopa was a risk factor for early death. In two previously reported patients, the diagnosis had been changed to multiple system atrophy and Machado‐Joseph disease. After a median disease duration of 18 years, cognitive impairment was found in only 19% of YOPD patients (13% of those younger than 60 years and 43% of those 60 years or older). Age was the most important factor for development of dementia, but female sex and positive family history of parkinsonism also had more modest predictive value. After a disease duration of 10 years or less, only 5% of patients were experiencing falls and 30% freezing, but all patients had developed L‐dopa‐related fluctuations and dyskinesias. The authors conclude that the mortality rate in parkinsonism starting before the age of 40 is increased in comparison to the normal population and is similar to the general Parkinson's disease population. Intellectual function and postural reflexes are usually well preserved for many years despite a long history of parkinsonism and the early and frequent occurrence of treatment complications, provided the patients remain biologically and chronologically young.
A community‐based study of sleep disorders in patients with Parkinson's disease
Authors: Tandberg Elise , Larsen Jan P. , Karlsen Karen
Published: May 2005

Sleep disorders are common and well documented in patients with Parkinson's disease (PD). However, most data on sleep in patients with PD are derived from selected patient populations. This community‐based survey evaluated the prevalence of and risk factors for sleep disturbances in an unselected group of 245 patients with PD and two control groups of similar age and sex distribution: 100 patients with another chronic disease (diabetes mellitus) and 100 healthy elderly persons. Nearly two thirds of the patients with PD reported sleep disorders, significantly more than among patients with diabetes (46%) and healthy control subjects (33%). About a third of the patients with PD rated their overall nighttime problem as moderate to severe. The most common sleep disorders reported by the patients with PD were frequent awakening (sleep fragmentation) and early awakening. Sleep initiation showed no significant difference compared with the control groups. Pain and cramps were not more prevalent among the patients with PD, but they were more likely to report sleep disturbed by myoclonic jerks. Use of sedatives was common in all three groups but significantly higher in the PD group than in the healthy elderly. Symptoms of depression and duration of levodopa treatment showed a significant correlation with sleep disorders in the PD group. This community‐based study confirms that sleep disorders are common and distressing in patients with PD. The strong correlation between depression and sleep disorders in patients with PD underlines the importance of identifying and treating both conditions in these patients.
Unified Huntington's disease rating scale: A follow up
Authors: Siesling Sabine , van Vugt Jeroen P. P. , Zwinderman Koos A. H. , Kieburtz Karl , Roos Raymund A. C.
Published: May 2005

An objective assessment of the clinical findings in patients with Huntington's disease (HD) is necessary for an evaluation of the longitudinal progression of the disease features. The Unified Huntington's Disease Rating Scale (UHDRS) is a scale to assess clinical performance and functional capacity. The authors examined the 1‐year change in UHDRS scores in 78 patients with HD examined either in Leiden, the Netherlands (24 men, 25 women), or in Rochester, New York, United States (12 men, 17 women). A significant decline was seen in motor function, measured with the total motor scale. The total dystonia score increased significantly; the total chorea score did not. The frequency of behavioral disorders tended to increase. The scores on independence scale, functional assessment, total functional capacity, and symbol digit decreased significantly. No relation was observed between the UHDRS items and the age at onset or duration of illness. Thirteen patients with 2‐year follow up showed a clear increase in score on the total motor scale and a decline on the independence scale and in total functional capacity. The UHDRS may also be used as a tool for determining therapeutic intervention. Annual evaluation of the total motor scale in every patient gives a clear description of the motor progression of the disease. The authors suggest performing a total UHDRS evaluation every second year for every HD patient as part of the routine longitudinal evaluation.
Effect of dystonia and botulinum toxin treatment on health‐related quality of life
Authors: Gudex Claire M. , Hawthorne Maurice R. , Butler Anthony G. , Duffey Philip
Published: May 2005

In view of the steadily rising demand for treatment of dystonia with botulinum toxin (BT), a relatively expensive neurologic paralytic agent, an exploratory study was undertaken to assess the extent to which dystonia and BT treatment affect the quality of people's lives. One hundred thirty adults with a current diagnosis of dystonia completed two generic measures of health‐related quality of life (HRQoL) at regular intervals over a minimum of 6 months. One hundred two participants were receiving regular injections of BT; 28 were not taking BT. The HRQoL instruments used were the EuroQol and the Short Form 36 health survey questionnaire (SF‐36). Compared with general population samples, study participants reported greater impairment on all EuroQol and SF‐36 dimensions and gave a lower rating to their own health status. Participants with nonfocal dystonia had significantly more problems with usual activities than participants with focal dystonia, and a higher number had problems with mobility and self‐care. The groups reported similar levels of pain and emotional well‐being. Small improvements in HRQoL were seen after the administration of BT, although few of these were statistically significant. The study results offer further psychometric evidence for the discriminant and construct validity of both the EuroQol and the SF‐36.
Unilateral painful legs and moving toes syndrome with moving fingers—evidence for distinct oscillators
Authors: Ebersbach Georg , Schelosky Ludwig , Schenkel Andreas , Scholz Udo , Poewe Werner
Published: May 2005

This case report presents a patient with painful legs and moving toes on the right side followed by the development of involuntary movements in his right hand. The frequencies of the semirhythmic muscle activities in both extremities were different. This finding excludes one central pacemaker for both and supports the notion that separate oscillators in the segmental interneuron pool of different spinal areas may drive the individual movements in this case.
Dipole moments of styrene/4‐vinylpyridine copolymers—I: Relation to the fraction of polar component
Authors: Yilmaz Elvan , Küçükyavuz Zühal
Published: May 2005

Mean‐square dipole moments for styrene/4‐vinylpyridine (S4VP) random copolymers were determined at five different temperatures, 25–60°C, in 1,4‐dioxane solution. The dipole moment behaviour was examined with respect to the increase in mole fraction of the polar monomer, 4‐vinylpyridine (4VP), in the copolymer. The behaviour observed was different from the general behaviour of similar copolymers.

The temperature coefficient of the dipole moment ratio was found to be zero, within experimental error, in the temperature interval 25–60°C.
Flammability of polyacrylonitrile and its copolymers II. Thermal behaviour and mechanism of degradation
Authors: Horrocks A. Richard , Zhang Jun , Hall Michael E.
Published: May 2005

Homopolymeric polyacrylonitrile and fibre‐forming copolymers containing either vinyl acetate or methyl acrylate comonomer have been studied by thermal analysis (DSC, TGA and DTG) at various heating rates (10–100 K min−1) and under air and nitrogen. Three well‐defined pyrolysis stages have been observed which occur over the temperature ranges 250–350°C, 350–550°C and above 550°C. Each stage involves a competition between volatilisation and cyclisation or char‐forming reactions which depends on heating rate and the presence or absence of oxygen.

The well‐established dominance of cyclisation in the 250–350°C temperature range obtained during carbon fibre production from acrylic precursors occurs only at low heating rates. At high heating rates, volatilisation dominates and this explains why acrylic polymers have high flammabilities when heating rapidly.

The full pyrolysis mechanism has been semi‐quantitatively analysed and the role that comonomers play discussed. This has enabled a fuller understanding of the potential burning behaviour of these polymers to be developed.
Phase equilibria of quasi‐binary systems consisting of multicomponent polymers 1 and 2. IV: Poly(ethylene oxide)/poly(propylene oxide) systems
Authors: Shirataki Hironobu , Kamide Kenji
Published: May 2005

To confirm the reliability of the theory of phase equibria of multicomponent polymer 1/multicomponent polymer 2 systems (i.e. quasi‐binary systems) and the method of computer experiment based on this theory (Brit. Polym. J., 23(1990)285; 23(1990)299; Polym. Int., 29(1992)219), could point curves (CPC), two‐phase volume ratios (R) and critical solution points (CSP) have been determined experimentally for the quasi‐binary mixtures of poly(ethylene oxide) (M¯w = 647, M¯w/M¯n = 1.15; M¯w and M¯n, the weight‐average and numberaverage molecular weights, respectively) and poly(propylene oxide) (M¯w = 2028, M¯w/M¯n = 1.08; and Mw = 2987, Mw/Mn = 1.13). The hydroxyl end groups of both polymers were methoxylated in advance by the Cooper & Booth method (Polymer, 18(1977)164). The thermodynamic interaction parameter between both polymers, χ12, and the concentration dependence parameters for the above quasi‐binary systems were determined by the method proposed in a previous paper (Brit. Polym. J., 23(1990)299). CPC, R and CSP values calculated on the basis of the theory are in good agreement with the values determined experimentally.
Effect of percolation on free‐radical polymerization of acrylamide in inverse microemulsion
Authors: Bartoň Jaroslav , Tiňo Jozef , Hloušková Zuzana , Stillhammerová Martina
Published: May 2005

The kinetics of free‐radical polymerization of acrylamide initiated by dibenzoyl peroxide in non‐percolating and percolating inverse microemulsions (toluene/sodium bis(2‐ethylhexyl) sulfosuccinate/water/acrylamide) and the properties of polyacrylamide particles formed from these inverse microemulsions were investigated. The acrylamide polymerization rate and polyacrylamide number‐average molecular mass depend on the acrylamide concentration in the dispersed phase of the inverse microemulsion. For non‐percolating inverse microemulsions these dependecies are described by the equation

where x and y have the values of 1.8 and 1.4 respectively, while for percolating inverse microemulsions the respective values of x and y are 1.1 and 0.4.

Data on polymer particle size and number‐average molecular mass of polyacrylamide in polymer particles were used for calculation of the average number of polymer chains in polymer particles for non‐percolating (approximately one chain per particle) and for percolating (more than two chains per particle) inverse microemulsions.

The spin probe (potassium nitrosodisulfonate, Fremy's salt) correlation time τc expressing the spin probe mobility in water‐swollen polymer particles and in polyacrylamide water solution pointed to the ‘collapsed’ state of polyacrylamide chains in polymer particles in both kinds of inverse microemulsions.

Besides the dependencies of polyacrylamide polymerization rate and of number‐average molecular mass of polyacrylamide on the acrylamide concentration in inverse microemulsions, the dependence of T50G values, characterizing the spin probe mobility in polymer particles of inverse microemulsions as a function of polyacrylamide concentration in the polymer particles, is different for nonpercolating and percolating inverse microemulsions.
Formation of interpolymer complexes between poly(monoethyl itaconate) and poly(N‐vinyl‐2‐pyrrolidone)
Authors: Cesteros Luis C. , Meaurio Emilio , Katime Issa
Published: May 2005

This paper reports on the interpolymer complex formation and polymer blends between poly(monoethyl itaconate) (PMEI) and poly(N‐vinyl‐2‐pyrrolidone) (PVP). The formation of the interpolymer complex was found to depend upon the solvent medium. Stoichiometry of the complexes prepared from methanol solutions, as calculated from elemental analysis, is close to 1 : 1. Specific interactions of PMEI/PVP complexes and blends of these polymers have been characterized by FTIR. Strong hydrogen bonding for complexes and blends has been found. A calorimetric study of the complexes and blends has been performed over a wide temperature range.
Inter‐ and intra‐molecular ionic interactions of polyampholyte: Carboxymethyl‐2‐diethylaminoethylcellulose
Authors: Zheng Guo‐zhen , Meshitsuka Gyosuke , Ishizu Atsushi
Published: May 2005

Carboxymethyl‐2‐diethylaminoethylcellulose (CM‐DEAE cellulose) was prepared by etherification of carboxymethylcellulose with diethylaminoethyl chloride in a NaOH solution. The behaviour of CM‐DEAE cellulose in aqueous solution was studied by viscosity and GPC measurements. The degree of substitution (DS) and existing states of DEAE substituents were examined by the use of proton NMR, and those of the CM substituents were observed with FT‐IR. The results reveal that the reduced viscosity and apparent molecular size of CM‐DEAE cellulose vary with the concentration of sodium chloride and changes in pH and DS. These phenomena can be explained in terms of inter‐ and intra‐molecular ionic interactions.
Studies on the transesterification of polycarbonate/poly(ethylene terephthalate) blends. II: Effect of transesterification on the compatibility and crystallization behaviour of the blends
Authors: Zheng Wen‐ge , Qi Zong‐neng , Wang Fu‐song
Published: May 2005

The effect of transesterification on the compatibility of polycarbonate poly(ethylene terephthalate) (PC/PET) blends and the crystallization and melting behaviour of PET was studied. The results show that with increase of the reaction extent, the compatibility of the blends was enhanced during melt‐processing, from completely incompatible to partially compatible, then to complete compatibility. In addition, with the increase of reaction extent, the crystallization ability and crystallinity of PET decreased. A new endotherm peak was discerned in DSC thermograms and its position and peak area were closely related to the reaction conditions, which was explained by the changes in the crystalline regions in the PC/PET blends. The effect of transesterification on the multiple melting behaviour of PET in PC/PET blends is also discussed.
Specific interaction between water‐soluble phospholipid polymer and liposome
Authors: Ishihara Kazuhiko , Nakabayashi Nobuo
Published: May 2005

A water‐soluble polymer having both a phospholipid polar group and an azobenzene group, poly(2‐methacryloyloxyethyl phosphorylcholine‐co‐p‐phenylazoacrylanilide) (poly(MPC‐co‐PAAn)) was synthesized and the interaction between the liposome of the phospholipid was investigated in comparison with other water‐soluble azoaromatic polymers. When the poly(MPC‐co‐PAAn) was incubated with dipalmitoylphosphatidylcholine (DPPC) lipo‐somes above these gel‐liquid crystalline temperatures, an electronic spectrum of azobenzene moiety, which is a hydrophobic probe, showed that the a copolymer chain exists under nonpolar circumstances. Thus, poly(MPC‐co‐PAAn) interacts with DPPC liposomes. On the other hand, other copolymers do not interact with the liposomes. Moreover, heat of the gel‐liquid crystalline transition of DPPC liposomes was increased by the presence of poly(MPC‐co‐PAAn). These findings clearly indicate that the poly(MPC‐co‐PAAn) has an affinity to the DPPC liposomes and hybridizes with liposomes based on the phospholipid polar group of the copolymer.
Vinylphosphonic esters as end‐capping agents in group transfer polymerization
Authors: Hertler Walter R.
Published: May 2005

Diethyl vinylphosphonate does not undergo group transfer polymerization (GTP), but does react with the silyl ketene acetal end group of PMMA prepared by GTP to give α‐(2‐diethoxyphosphinylethyl) PMMA. Copolymerization of MMA and small amounts of diethyl vinylphosphonate led to copolymer. The telechelic PMMA diphosphonic acid, α‐(2‐dihydroxyphosphinylethyl) ω‐dihydroxyphosphinylPMMA, was synthesized by initiation of GTP of MMA with diethyl 3‐methoxy‐3‐trimethylsiloxy‐2‐propene‐1‐phosphonate, followed by termination with diethyl vinylphosphonate, silylation of the phosphonic ester with bromotrimethylsilane, and hydrolysis. Reaction of living poly (methyl methacrylateco‐n‐butyl methacrylate), prepared by GTP, with bis (trimethylsilyl) vinylphosphonate followed by hydrolysis gave α‐(2‐dihydroxyphosphinylethyl) poly (methyl methacrylateco‐n‐butyl methacrylate).
New telechelic polymers and sequential copolymers by polyfunctional initiator‐transfer agents (inifers) LVII. Chlorine telechelic poly(p‐chlorostyrene)
Authors: Zsuga M. , Kennedy J. P.
Published: May 2005

The polymerization of p‐chlorostyrene (pClSt) under carbocationic conditions has been investigated. The use of binifers 1,4‐di(2‐chloro‐2‐propyl) benzene (pDCC) and 1,3‐di(2‐chloro‐2‐propyl)‐5‐tert‐butylbenzene (m‐tBuDCC) in conjunction with BCl3 coinitiator in CH3Cl diluent at −60 and −35°C give α,ω‐di‐benzylic chlorine‐capped polymer sClPpClStCls. According to kinetic investigations the inifer mechanism is operative and both binifers are efficient in controlling the end structures, molecular weights, and to a certain extent molecular weight distributions (MWD). Strong circumstantial evidences have been generated to demonstrate the satisfactory synthesis of sClPpClStCls and the absence of indanyl end‐groups, i.e., structural considerations, linearity of inifer plots, quantitative Cl end‐group microanalysis, FTIR spectroscopy, and blocking experiments. The latter involved the blocking of THF from the sec‐benzylic chlorine end‐groups by AgPF6 and thus led to the synthesis of a new triblock copolymer PTHF‐b‐PpClSt‐b‐PTHF. Interestingly, the isotactic content (mm triads and mmmm pentads) of PpClSt is significantly higher than that of polymer prepared by free‐radical induced polymerization. The Tg of a PpClSt of M̄n = 5700 g/mol was 123°C.
Polyesters, polyurethanes, and epoxy resin derived from 2,2′‐(1,4‐phenylenedivinylene)bis‐5‐hydroxypyridine
Authors: Mikroyannidis John A.
Published: May 2005

2,2′‐(1,4‐Phenylenedivinylene)bis‐5‐hydroxypyridine (PBHP) was used as a starting material for preparing new polyesters and polyurethanes as well as a diepoxide‐bearing styrylpyridine segments. The diesters were prepared by reacting PBHP with terephthaloyl or adipoyl dichloride utilizing the interfacial polycondensation method. The diesters were prepared from the reaction of PBHP with tolylene diisocyanate or methylenebis(4‐phenylisocyanate). In addition, a model diester and diurethane were synthesized by reacting PBHP with benzoyl chloride and phenyl isocyanate, respectively. Both model compounds and polymers were characterized by IR and 1H‐NMR spectroscopy, as well as by DTA and TGA. A diepoxide was also prepared from the reaction of PBHP with epichlorohydrin which was polymerized in the presence of 4,4′‐diaminodiphenylsulfone. The polyester derived from PBHP and terephthaloyl dichloride was the most thermostable polymer obtained. It was stable in N2 up to 355°C and afforded an anaerobic char yield of 59% at 800°C. The thermal stabilities of polymers were improved by curing.
Brittle fracture of entangled polymers
Authors: Mikos Antonios G. , Peppas Nikolaos A.
Published: May 2005

A stochastic model is presented to calculate the number of chain segments entangled about a unit plane when the segment length is a stochastic variable. This crossing density to which the brittle fracture energy and the critical strength of entangled polymers scale is a function of the number of moles of entanglement network strands per unit volume and the mesh size of the entanglement network. Experimental results of the molecular weight dependence of the fracture energy and strength validate the theoretical predictions.
Third‐order interaction approximation for linear polymer chains
Authors: Xu Jianmin , Song Xubing , Zhou Zhiping , Yan Deyue
Published: May 2005

Third‐order interactions imposed by a pair of atoms separated by five bonds are taken into account in computations of the mean‐square end‐to‐end distance and the mean‐square radius of gyration for linear polymer chains. The statistical weight matrices are established on the basis of the rotational isomeric state model. The conformational energy of n‐hexane is calculated as a function of the CC bond rotation angles. The third‐order interaction energy is obtained by comparison with that of n‐pentane. The characteristic ratio of polymethylene is 6.6 in the third‐order interaction approximation, which is in agreement with experimental data.
Multifractal Description of a Rugged Fineparticle Profile
Authors: Kaye Brian H.
Published: May 2005

Mandelbrot has extended the concept of classical dimensional description of physical systems to include fractional values which describe the ruggedness of a structure. Thus if one has a dimension of 1.2 one knows that one is dealing with a line which fills space more efficiently than a line which has dimension of 1.1. A mathematical curve which exhibits ideal fractal structure has the same appearance when viewed at any level of scrutiny. Kaye and co‐workers applied the concept of fractal mathematics to the description of the boundaries of fineparticle profiles. As demonstrated in this communication a natural fractal boundary in contrast with an ideal fractal can exhibit different fractal structures over different ranges of scrutiny. As a consequence one should always report the scale of scrutiny employed when examining the fractal structure of natural boundaries. Data is presented demonstrating the fractal/euclidean boundary structure manifest by aluminum shot fineparticles examined at various levels of scrutiny. The relationship between fractal descriptors of fineparticle boundaries and the Fourier analysis of geometric signature waveforms for describing the structure of fineparticles is explored. Data presented by Flook on the physical significance of the various co‐efficients of a Fourier analysis of a signature waveform is correlated with the fractal description of the ruggedness of a profile.
Sampling Powders for Shape Description
Authors: Hawkins Arthur E. , Davies Kenneth W.
Published: May 2005

For some time studies have been made relating the values obtained from simple shape description to bulk powder properties. More recently the detailed mathematical description of particle outline has become possible and quite powerful techniques have been developed. These techniques may be used for the regeneration by computer of the shape and, more importantly, for studies relating shape to individual particle behaviour and to bulk powder properties. Quite inadequate attention has been directed to the task of obtaining from the laboratory sample of the bulk powder a representative sample of shapes without bias. In this communication the considerations to be included in the sampling procedure are reviewed and a possible solution to the problems posed is presented.
Response of the Coulter Counter® Model ZM to Spheres
Authors: Harfield John G. , Wharton R. Tony , Lines Roy W.
Published: May 2005

Most existing theories of the response of electrical sensing zone particle size analysers, for instance of the type Coulter Counter®, predict that a significant deviation from sizing linearity will occur at and above some 40% of the aperture diameter. Practical experience, at least for the only test models available ‐ latex spheres ‐ shows that this is not the case in practice. Linear particle response up to 80% of the aperture diameter has been established, confirming the prediction recently made by Scarlett in a new response theory.
Comparison of Techniques for Measuring the Size of Fine non‐spherical particles
Authors: Seville Jonathan P. K. , Coury José R. , Ghadiri Mojtaba , Clift Roland
Published: May 2005

Three general types of commercial particle sizing instruments have been tested with redispersed fly ash and devolatilised coal char in the size range 0.5 to 5 μm. Results are compared with volume‐equivalent diameters obtained by Coulter Counter. Single‐particle light‐scattering counters are found to oversize fly ash, primarily because of the irregular particle shape, but generally to undersize the strongly absorbing char particles. The Malvern sizer, based on Fraunhofer diffraction analysis, grossly oversizes fly ash dispersed in water, probably because most of the particles are too small for the Fraunhofer approximation to be valid; results for carbon char are closer to the expected values, although results for particles dispersed in air and in water show some disagreement. The Aerodynamic Particle Sizer undersizes irregular particles substantially, probably because of increased drag resulting from the irregular shape and tumbling motion of these particles.
Errors in the Determination of Particle Size Distributions Caused by coincidences in optical particle counters
Authors: Raasch Jürgen , Umhauer Heinz
Published: May 2005

When performing particle size analysis by scattered light, coincidences in the measuring volume of optical particle counters not only cause too small a particle concentration to be measured, but also a size distribution to be obtained which is systematically shifted towards coarser particle sizes. It is pointed out in this paper how this shift can be precalculated when the true distribution is given. The results show under which conditions a correction of the measured distribution is indispensable.
The Role of Fractal Quantities, as Specific Surface and Tortuosities, for physical properties of porous media
Authors: Pape Hansgeorg , Riepe Lutz , Schopper Jürgen R.
Published: May 2005

Besides the knowledge of material constants of the homogeneous phases of a disperse system, a good understanding of its geometrical properties is necessary for describing physical processes. In order to characterize the shape of the interface between solids and pore space with respect to the irregularities in all orders of magnitude, the fractal dimension has proved to be an informative parameter. By this study the theory of fractal dimensions, in three‐dimensional space originally limited to topological curves, surfaces and volumes, is extended into physical properties like specific surface, tortuosity, porosity and formation factor with “physical” dimensions −1 or 0 as an exponent of the unit of length. The typical properties of the true fractals are transferable to some of these derived parameters. This leads to power laws describing the dependence of the particular measure on the resolution length. With special models, which seem to be of widespread validity in nature, petrophysical considerations lead to further power laws for the rest of the physical parameters, dependent on discrete length parameters such as grain radius and pore radius. By determination of the exponents of such independent power laws, a better particle characterization is possible, as the fractal dimension of the surface alone may be misleading, especially when the grain size of the particles is not uniform.
Comminution of Irregularly Shaped Particles by Slow Compression: Interpretation of the size distributions of progeny particles as mixed distributions
Authors: Hanisch Jens , Schubert Heinrich
Published: May 2005

The evaluation of particle size distributions of comminution products often shows that the experimental distributions cannot be represented by one of the well‐known functions (GGS, RRSB, log‐normal distributions). Although in some cases a more or less satisfactory approximation to one of these functions can be made, a physically meaningful interpretation is generally impossible. Using the frequency curve, it can often be shown that mixed distributions, represented by several statistical assemblies, do exist. In this paper the progeny size distributions of quartzite formed by slow compression comminution of single grains and particle beds as well as of the comminution products of a roller mill are interpreted as superpositions of several statistical assemblies each of which can be represented by a truncated log‐normal distribution.
Representation and Evaluation of Particle Size Analysis Data
Authors: Leschonski Kurt
Published: May 2005

While editing the first issues of Particle Characterization it has been recognized by the editors that the papers submitted differ widely in the representation of data and in the nomenclature chosen to characterize such common variables as particle size, different equivalent particle diameters, average particle sizes, cumulative and density values of a distribution etc. In oder to make papers published in this Journal more readily assimilable and graphs representing particle size analysis data instantly recognizable by using agreed upon standardized nomenclature the following paper has been submitted by one of the editors. It was first presented at the Harold Heywood Memorial Symposium, September 1974, at the University of Technology, Loughborough, U. K.
Correlation of Simultaneously Measured Droplet Sizes and Velocities in nozzle sprays
Authors: Bauckhage Klaus , Floegel Hans‐H.
Published: May 2005

The application of a new LDA method which simultaneously measures the size and velocity of small water droplets in the spray cone of a fan type water nozzle is described. As the phase difference between adjacent photomultipliers responding to signals from a fringe mode LDA is linearly proportional to the diameter of the spherical particle in the measuring volume, the new instrument allows, for long distances between the optical devices and the measuring volume in the spray, non‐invasive measurements and from these the correlation of size and velocity of the individual droplet in order to establish two‐dimensional distributions. From the new LDA instrument one receives definite information about the volume‐flow concentration in the measuring point of an enclosed flow situation.
The Determination of Particle Size Distribution Using Combined gravitational and centrifugal sedimentation analysis
Authors: Laapas Heikki R. , Lahtinen Ulla‐Riitta
Published: May 2005

Combined gravitational and centrifugal sedimentation analysis was studied using a Sedigraph X‐ray sedimentometer and a Ladal pipette centrifuge. The test powders were talc, calcite and lead oxide. The purpose of the study was to examine the possibilities of extending the sedimentation analysis towards finer sizes by the use of centrifugal force. All the test samples could be analysed down to 0.04–0.05 μm by the combined sedimentation procedure with reasonable accuracy and the results were matched to give a uniform distribution. It was also shown to be preferable to present the size analysis data in a log‐probability scale, as it gives the means to easily distinguish materials with different particle size characteristics and to estimate the actual distribution by a statistical function.
Results Obtained with a New Instrument for the Measurement of particle size distributions from diffraction patterns
Authors: Heuer Michael , Leschonski Kurt
Published: May 2005

For several years the size distributions of particulate matter have increasingly been determined by using diffraction pattern analysis.

In order to evaluate particle size distributions from the far field intensity distribution of light diffracted by a distribution of particles, a linear set of equations must be solved. Since, in many cases of application, conventional methods for solving linear sets of equations become unstable, the calculated particle size distribution may also be grossly in error. By applying special, known mathematical methods we succeeded in obtaining a parameterfree solution of the above problem.

After a brief description of the mathematical method used, a diffraction pattern analyser will be presented as well as some experimental results obtained with it. The results obtained with aerosols and suspensions come from experiments performed with narrow‐sized latexes and mono‐ and bi‐modal particle size distributions of limestone and quartz.
Measurement of Particle Orientation Distribution by a Stereological Method
Authors: Kanatani Ken‐ichi
Published: May 2005

Practical procedures are described for a stereological method which determines the spatial distribution of particle orientation from the distribution observed on cross sections. First, the two dimensional distribution of needle‐like particles is determined by counting the number of intersections with parallel probe lines. Next, the three dimensional distribution of needle‐like particles is determined by counting the number of intersections with a cutting plane. Then, the three dimensional distribution of disklike particles is determined by counting the number of intersections with a probe line. Finally, the distribution of disklike particles is determined by measuring the total length of the cross sections on a cutting plane.
The Influence of Particle Attrition on the Wall Friction Coefficient of a free flowing particulate solid
Authors: van den Bergh Wim J. B. , van Dalen G. , Scarlett Brian
Published: May 2005

In this paper a reciprocating shear cell, which has been developed to measure dynamic wall friction, is described. The cell has also been used to study the attrition behaviour of sand samples at the bounding wall. This attrition causes a considerable change in the angle of wall friction.
On Using Fourier Series in Characterizing Particle Shape
Authors: Bandemer Hans , Albrecht Matthias , Kraut Andre
Published: May 2005

This paper starts from the fact that the Fourier coefficients of the contour of a particle are commonly used to describe its shape, for example by Meloy's law of morphological coefficients. The authors point to the sensitivity of the Fourier coefficients of jump discontinuities of the contour or of one of its derivatives. Explicit formulae for this dependence are reported and are used to suggest a stochastic model, the sensitivity is demonstrated by two examples with calculated results.