bluuebunny/crossref_metadata_2025 huggingface dataset:
Case studies in international tobacco surveillance: cigarette smuggling in Brazil
Authors: Shafey O , Cokkinides V , Cavalcante T M , Teixeira M , Vianna C , Thun M
Published: August 2002

Objective:This article is the first in a series of international case studies developed by the American Cancer Society to illustrate use of publicly available surveillance data for regional tobacco control.

Design:A descriptive analysis of Brazil and Paraguay cigarette production and trade data from official sources.

Methods:Per capita cigarette consumption for Brazil and its neighbour was calculated from 1970 to 1998 using data on production, imports, and exports from NATIONS, the National Tobacco Information Online System.

Results:A 63% decrease was observed in the estimate of per capita consumption of cigarettes in Brazil between 1986 and 1998 (from 1913 cigarettes per person in 1986 to 714 cigarettes per person in 1998) and a 16-fold increase in Paraguay was observed during the same period (from 678 cigarettes per person in 1986 to 10 929 cigarettes per person in 1998). Following Brazil's 1999 passage of a 150% cigarette export tax, cigarette exports fell 89% and Brazil's estimated per capita consumption rose to 1990 levels (based on preliminary data). Per capita consumption in Paraguay also fell to 1990 levels.

Conclusions:These trends coincide with local evidence that large volumes of cigarettes manufactured in Brazil for export to Paraguay are smuggled back and consumed as tax-free contraband in Brazil. It is hoped that this case study will draw wider public attention to the problems that smuggling presents for tobacco control, help identify other countries confronting similar issues, and stimulate effective interventions.
Association between exposure to environmental tobacco smoke and the development of acute coronary syndromes: the CARDIO2000 case–control study
Authors: Pitsavos C , Panagiotakos D B , Chrysohoou C , Skoumas J , Tzioumis K , Stefanadis C , Toutouzas P
Published: August 2002

Objective:To investigate the association between environmental tobacco smoke (ETS) exposure (at least 30 minutes a day) and the risk of developing acute coronary syndromes (ACS).

Design and setting:The CARDIO2000 is a case–control study which was conducted in Greece from 2000 to 2001. Cases included 847 individuals with a first event of ACS and 1078 cardiovascular disease-free controls. Cases and controls were frequency matched on age (within three years of age), sex, and region.

Main outcome measures:ACS was defined as a diagnosis of first acute myocardial infarction or unstable angina.

Main independent variable:Exposure to ETS was measured by self report as follows: after the second day of hospitalisation for the cases, and at the entry for the controls, participants were asked whether they were currently exposed to tobacco smoke from other people (home and/or work) for more than 30 minutes a day. The responses were categorised into three levels: no exposure, occasional exposure (< 3 times per week), and regular exposure. In addition participants were asked how many years they had been exposed. Because these were self reported assessments and prone to bias, the results were compared to reports obtained from subjects' relatives or friends, using the Kendal's τ coefficient that showed high agreement.

Results:731 (86%) of the patients and 605 (56%) of the controls reported current exposure of 30 minutes per day or more to ETS. Among current non-smokers, cases were 47% more likely to report regular exposure to ETS (odds ratio (OR) 1.47, 95% confidence interval (CI) 1.26 to 1.80) compared to controls. Exposure to ETS at work was associated with a greater risk of ACS compared to home exposure (+97%v+33%). The risk of ACS was also raised in active smokers (OR 2.83, 95% CI 2.07 to 3.31) regularly exposed to ETS.

Conclusions:This study supports the hypothesis that exposure to ETS increases the risk of developing ACS. The consistency of these findings with the existing totality of evidence presented in the literature supports the role of ETS in the aetiology of ACS.
Online sales: profit without question
Authors: Bryant J A , Cody M J , Murphy S T
Published: August 2002

Objectives:To examine the ease with which underage smokers can purchase cigarettes online using money orders and to evaluate the effectiveness of internet filtering programs in blocking access to internet cigarette vendors (ICVs).

Design:Four young people purchased 32 money orders using 32 different names to buy one carton of cigarettes for each named individual. Each money order was subsequently mailed to a different ICV in the USA. No age related information accompanied these online orders. Two internet filtering programs (“Bess” and filtertobacco.org) were tested for their relative efficacy in blocking access to ICV sites.

Results:Of the 32 orders placed, four orders never reached the intended ICV. Of the remaining 28 orders, 20 (71%) were filled despite a lack of age verification. Only four (14%) of the orders received were rejected because they lacked proof of age. “Bess” blocked access to 84% and filtertobacco.org to 94% of the ICV sites.

Conclusions:Although underage smokers can easily purchase cigarettes online using money orders, access to these sites can be largely blocked if appropriate filtering devices are installed.
Young adults' opinions of Philip Morris and its television advertising
Authors: Henriksen L , Fortmann S P
Published: August 2002

Objective:To determine what young people think about the tobacco company Philip Morris and how it affects their evaluations of the company's new television advertising.

Design:Data were gathered in the context of a controlled experiment in which participants saw four Philip Morris ads about youth smoking prevention, four Philip Morris ads about charitable works, or four Anheuser-Busch ads about preventing underage drinking (the control group). Knowledge and opinion of Philip Morris were measured before ad exposure.

Setting:A California state university in the San Francisco Bay area.

Subjects:A convenience sample of undergraduates (n = 218) aged 18–25 years.

Main outcome measures:Advertising evaluation measured by 12 semantic differential scales.

Results:A little more than half of the students knew that Philip Morris is a tobacco company. Neither this knowledge nor students' smoking status was related to their opinion of the company. Philip Morris ads were rated less favourably by students who were aware that the sponsor is a tobacco company than by students who were unaware.

Conclusions:Advertisements designed to discredit the tobacco industry typically avoid references to specific companies. This study suggests that such counter-advertising would benefit from teaching audiences about the industry's corporate identities.
Is smoking a communicable disease? Effect of exposure to ever smokers in school tutor groups on the risk of incident smoking in the first year of secondary school
Authors: Molyneux A , Lewis S , Antoniak M , Hubbard R , McNeill A , Godfrey C , Madeley R , Britton J
Published: August 2002

Objective:To estimate the effect of joining a first year secondary school tutor group with a high prevalence of ever smoking on the risk of incident smoking in schoolchildren.

Design:Cross-sectional questionnaire survey.

Setting:10 randomly selected secondary schools in Nottinghamshire, UK.

Participants:Pupils in years (grades) 7–11 (aged 11–16 years).

Main outcome measure:Incident smoking in the first year of secondary education, defined as pupils who reported smoking their first cigarette during year 7.

Results:Of 6522 pupils (75% of those eligible) who completed the questionnaire, 17% were current smokers and 49% had ever smoked, of whom 23% had started smoking in year 7. Incident smoking in year 7 was more common in girls, in children with parents or siblings who smoke, and in more deprived children, and was independently increased in relation to the proportion of ever smokers in the year 7 tutor group joined by the child (adjusted odds ratio of incident smoking for a child joining a year 7 tutor group in the highest relative to the lowest quartile of ever smoking prevalence 1.45, 95% confidence interval (CI) 1.11 to 1.89). Exposure to ever smokers in year 7 tutor groups also accounted for most of the increased risk of incident smoking associated with socioeconomic deprivation.

Conclusions:The risk of incident smoking in children entering secondary education is independently increased by exposure to other ever smokers in school tutor groups. Incident smoking in adolescents is thus to some extent a communicable disorder, and may be partly preventable by policies that reduce exposure to smoking at school.
Exposure to teachers smoking and adolescent smoking behaviour: analysis of cross sectional data from Denmark
Authors: Poulsen L H , Osler M , Roberts C , Due P , Damsgaard M T , Holstein B E
Published: August 2002

Objective:To determine whether adolescent smoking behaviour is associated with their perceived exposure to teachers or other pupils smoking at school, after adjustment for exposure to smoking at home, in school, and best friends smoking.

Design:Logistic regression analysis of cross sectional data from students in Denmark.

Subjects:1515 grade 9 students (mean age 15.8) from 90 classes in 48 Danish schools.

Outcome measure:Self reported smoking behaviour; daily smoking and heavy smoking, defined as those smoking more than 20 cigarettes per week.

Results:Of the students in this study, 62% of boys and 60% of girls reported being exposed to teachers smoking outdoors on the school premises. The proportion of boys and girls reporting to have been exposed to teachers smoking inside the school building were 86% and 88%, respectively. Furthermore, 91% of boys and 92% of girls reported that they had seen other students smoking outdoors on the school premises. Adolescents’ perceived exposure to teachers smoking outdoors on the school premises was significantly associated with daily smoking, having adjusted for sex, exposure to teachers smoking indoors at school and pupils smoking outdoors at school, as well as the smoking behaviour of mother, father, and best friend (odds ratio (OR) 1.8, 95% confidence interval 1.2 to 2.8). Adolescents’ perceived exposure to teachers smoking inside the school building was not associated with daily smoking (OR 0.9, 95% CI 0.5 to 1.6) and perceived exposure to pupils smoking outdoors was not associated with daily smoking (adjusted OR 1.5, 95% CI 0.5 to 4.4). There were similar findings with heavy smoking as the outcome variable.

Conclusions:Teachers smoking during school hours is associated with adolescent smoking. This finding has implications for future tobacco prevention strategies in schools in many countries with liberal smoking policies where it might provide support for those working to establish smokefree schools.
The shredding of BAT's defence: McCabevBritish American Tobacco Australia
Authors: Liberman J
Published: August 2002

On 11 April 2002, a Victorian supreme court jury ordered British American Tobacco Australia to pay Rolah McCabe $A700 000 in damages. Rolah McCabe is a 51 year old woman dying of lung cancer. She is the first smoker ever in Australia to obtain a damages verdict against the tobacco industry
BAT flouts tobacco-free World Cup policy
Authors: Assunta M
Published: August 2002

In Malaysia, British American Tobacco flouted the World Cup of football's no-tobacco ruling
CONVEX MULTIVARIABLE TRACE FUNCTIONS
Authors: LIEB ELLIOTT H. , PEDERSEN GERT K.
Published: August 2002

For any densely defined, lower semi-continuous trace τ on a C*-algebra A with mutually commuting C*-subalgebras A1, A2, … An, and a convex function f of n variables, we give a short proof of the fact that the function (x1, x2, …, xn)→ τ (f (x1, x2, …, xn)) is convex on the space [Formula: see text]. If furthermore the function f is log-convex or root-convex, so is the corresponding trace function. We also introduce a generalization of log-convexity and root-convexity called ℓ-convexity, show how it applies to traces, and give some examples. In particular we show that the Kadison–Fuglede determinant is concave and that the trace of an operator mean is always dominated by the corresponding mean of the trace values.
HOW SHOULD ONE DEFINE ENTROPY PRODUCTION FOR NONEQUILIBRIUM QUANTUM SPIN SYSTEMS?
Authors: RUELLE DAVID
Published: August 2002

This paper discusses entropy production in nonequilibrium steady states for infinite quantum spin systems. Rigorous results have been obtained recently in this area, but a physical discussion shows that some questions of principle remain to be clarified.
ON A SUBFACTOR ANALOGUE OF THE SECOND COHOMOLOGY
Authors: IZUMI MASAKI , KOSAKI HIDEKI
Published: August 2002

The set of equivalence classes of Longo's Q-systems is shown to serve as a right subfactor analogue of the second cohomology. This "cohomology" is computed for several classes of subfactors, which tells us if a subfactor is uniquely determined up to inner conjugacy by the associated canonical endomorphism. As a byproduct of our analysis, two different groups of order 64 are shown to possess the same representation category as an abstract tensor category. Thus, this category has two permutation symmetries with non-isomorphic groups via the Doplicher–Roberts duality.
DERIVATIVES WITH TWISTS
Authors: JAFFE ARTHUR
Published: August 2002

We study derivatives on an interval of length ℓ (or the associated circle of the same length), and certain pseudo-differential operators that arise as their fractional powers. We compare different translations across the interval (around the circle) that are characterized by a twisting angle. These results have application in
ANY COMPACT GROUP IS A GAUGE GROUP
Authors: DOPLICHER SERGIO , PIACITELLI GHERARDO
Published: August 2002

The assignment of the local observables in the vacuum sector, fulfilling the standard axioms of local quantum theory, is known to determine uniquely a compact group G of gauge transformations of the first kind together with a central involutive element k of G, and a complete normal algebra of fields carrying the localizable charges, on which k defines the Bose/Fermi grading.

We show here that any such pair {G, k}, where G is compact metrizable, does actually appear. The corresponding model can be chosen to fulfill also the split property.

This is not a dynamical phenomenon: a given {G, k} arises as the gauge group of a model where the local algebras of observables are a suitable subnet of local algebras of a possibly infinite product of free field theories.
MATRIX VALUED SPHERICAL FUNCTIONS ASSOCIATED TO THE THREE DIMENSIONAL HYPERBOLIC SPACE
Authors: GRÜNBAUM F. A. , PACHARONI I. , TIRAO J.
Published: August 2002

The main purpose of this paper is to compute all irreducible spherical functions on [Formula: see text] of arbitrary type [Formula: see text], where K = SU (2). This is accomplished by associating to a spherical function Φ on G a matrix valued function H on the three dimensional hyperbolic space ℍ = G/K. The entries of H are solutions of two coupled systems of ordinary differential equations. By an appropriate twisting involving Hahn polynomials we uncouple one of the systems and express the entries of H in terms of Gauss' functions 2F1. Just as in the compact instance treated in [7], there is a useful role for a special class of generalized hypergeometric functions p+1 Fp.
CLIFFORD'S THEOREM AND HIGHER RANK VECTOR BUNDLES
Authors: MERCAT VINCENT
Published: August 2002

We give here a refinement of the classical Clifford's theorem for the upper bound of the number of independent global sections of a semistable vector bundle on a smooth curve. We also conjecture a new version of this theorem that takes into account the Clifford index of the curve. In the case of a bi-elliptic curve we obtain a very precise bound. Finally we study the case of rank 2 bundles.
REMARKS ON THE f0(400–1200) SCALAR MESON AS THE DYNAMICALLY GENERATED CHIRAL PARTNER OF THE PION
Authors: VAN BEVEREN EEF , KLEEFELD FRIEDER , RUPP GEORGE , SCADRON MICHAEL D.
Published: August 2002

The quark-level linear σ model (LσM) is revisited, in particular concerning the identification of the f0(400–1200) (or σ(600)) scalar meson as the chiral partner of the pion. We demonstrate the predictive power of the LσM through the ππ and πNs-wave scattering lengths, as well as several electromagnetic, weak, and strong decays of pseudoscalar and vector mesons. The ease with which the data for these observables are reproduced in the LσM lends credit to the necessity to include the σ as a fundamental [Formula: see text] degree of freedom, to be contrasted with approaches like chiral perturbation theory or the confining NJL model of Shakin and Wang.
GAUGE TRANSFORMATIONS OF THE NON-ABELIAN TWO-FORM
Authors: LAHIRI AMITABHA
Published: August 2002

A novel inhomogeneous gauge transformation law is proposed for a non-Abelian adjoint two-form potential in four dimensions. Rules for constructing actions invariant under this are given. The auxiliary vector field which appears in some of these theories transforms like a second connection. Some of the actions also show a local symmetry which is not generated by any local constraint, a novelty for classical field theories. Both types of symmetries change the action by total divergences, suggesting that boundary degrees of freedom have to be taken into account for local quantization.
NON-ADIABATIC BERRY'S QUANTUM PHASES IN ANISOTROPIC UNIVERSES
Authors: DE ASSIS J. G. , BEZERRA V. B. , FURTADO CLÁUDIO
Published: August 2002

We use the theory of time-dependent invariants of Lewis and Riesenfeld to calculate the non-adiabatic Berry's quantum phase acquired by scalar particles in some anisotropic universes.
TORSION QUINTESSENCE
Authors: CAPOZZIELLO SALVATORE
Published: August 2002

A natural way to obtain quintessence, i.e. negative pressure contributions in cosmological dynamics and then accelerated behavior of the Hubble fluid, is to take into account a torsion fluid whose effects become relevant at large scale. We investigate a model where a totally antisymmetric torsion field is taken into account and discuss the conditions to obtain quintessence. We obtain exact solutions where dust dominated Friedmann behavior is recovered as soon as torsion effects are not relevant.
CAUSAL CLASSICAL THEORY OF RADIATION DAMPING
Authors: HUSSEIN M. S. , PATO M. P. , WELLS J. C.
Published: August 2002

It is shown how initial conditions can be appropriately defined for the integration of Lorentz–Dirac equations of motion. The integration is performed forward in time. The theory is applied to the case of the motion of an electron in an intense laser pulse, relevant to nonlinear Compton scattering.
LAMELLAR STRUCTURES INDUCED BY COUPLED ELECTROMAGNETIC AND SHEAR FIELDS: A DEFINING CHARACTER OF ER/MR ACITIVITY
Authors: HENLEY S. , FILISKO F. E.
Published: August 2002

In this article it will be demonstrated that columns of particles bridging the electrodes are not the characteristic feature of ER fluids under field. Instead a higher level of order, particle lamellae, must develop under shear and E field if a suspension is to be a legetimate ER fluid.
THE INTERACTION BETWEEN ELECTRORHEOLOGICAL PARTICLES IN AC ELECTRIC FIELD STUDIED USING OPTICAL TWEEZERS
Authors: XU J. , DONG X. , CHEN Z. Y. , JIANG Y. G. , ZHOU L. W.
Published: August 2002

The dipole interaction between a pair of electrorheological (ER) particles under an external AC electric field was confirmed in a dynamic case using optical tweezers positioning and a system of high speed imaging and image processing. By measuring the interactions between two micron-sized ER particles with both central distance and structure forming time, the structure response time and the interaction strength were obtained for the particles under an AC electric field. The spacial resolution of the optical tweezers-high speed imaging-image processing system is 0.26μm. The sampling rate of the high-speed video recorder is up to 8000 frame/s with the corresponding time resolution being 0.125 ms.
MAGNETIC INTERACTIONS OF CHAINS FORMED BY FERROMAGNETIC SPHERES
Authors: LACIS S. , ZAVICKIS E. , BOSSIS G.
Published: August 2002

General properties of sphere-chain and chain-chain structures are analysed for homogeneously magnetized spheres. For field aligned structures the local maximum of the magnetic force is observed at H0/MS ≈ 0.5. The magnetic saturation effects are accounted by the Frölich-Kennelly law. Outlines of the approximate methodology of multi-chain interaction are given together with the test results.
PARTICLE DYNAMICS OF STRUCTURE FORMATION AND DISINTEGRATION IN A MODEL MAGNETORHEOLOGICAL FLUID
Authors: CUTILLAS S. , LIU J.
Published: August 2002

Using diffusing-wave spectroscopy (DWS), we studied experimentally the particle dynamics for a density matched superparamagnetic polystyrene colloid in a refractive index nearly matched multiple-layered cell. Particle dynamics is probed during structure formation and disintegration, when a 0.2 Hz square-wave magnetic field was turned on for 4 s and off for 1 s. The correlation function shows that the particles move slower and more restricted when the magnetic field is on. Even during the off cycle of the magnetic field, the particles' motion is not free but still constrained with a less degree than that when the field is on. Thus, it takes more than 1 s for the induced structure to disintegrate. As the magnetic field strength increases, so does the degree of constrain for both the on and off cycle of the magnetic field and the differences between them. Modified telegrapher theory is found to be valid for our strongly absorbing and limited multiple scattering sample.
SHORT TIME DYNAMIC STRUCTURE FORMATION OF CARBON-DOPED TiO2 ER FLUIDS WITH DIFFERENT CONDUCTIVITY USING DIFFUSING WAVE SPECTROSCOPY
Authors: ZHANG L. F. , DONG X. , XU J. , JIANG Y. G. , ZHOU L. W. , ZHU Y. H.
Published: August 2002

A new method of doing DWS (diffusing wave spectroscopy) measurement has been developed by using high speed CCD to investigate the structure and the dynamics of nonergodic and concentrated system such as electrorheological (ER) fluids under high electric field. The DWS results from the CCD method and the traditional method using a single-mode optical fiber agree well for ergodic system. The structure response time is obtained by measuring the transmittance of the sample under different electric field. The force response time of about 100ms is obtained from the time-dependent diffusion coefficient. In this paper, by comparing the time variation of transmittance and diffusion coefficient obtained under different conditions, a criterion of fast and strong responses of practical ER fluids to electric field is provided.
ELECTRIC-FIELD-INDUCED LAMELLAR STRUCTURES IN MAGNETIC FLUIDS — A 2D DIFFUSION MODEL
Authors: RILEY BRETT , BHATTACHARYA ANIKET , JOHNSON MICHAEL , DUAN XIAODONG , LUO WEILI
Published: August 2002

A lamellar pattern can form in a thin magnetic fluid layer when the applied electric field is above a critical value. A 2D simulation is performed to study the field-induced phase separation and the pattern by using the mass continuity equation. The simulation produces the similar structure in field but does not match the experimental growth law.
FIELD INDUCED PHASE TRANSITION FOR SUSPENSION OF MONOSIZED SPHERES
Authors: MEN S. , MEUNIER A. , MÉTAYER C. , BOSSIS G.
Published: August 2002

We have developed a new Ewald summation for a three-dimensional dipolar system with two-dimensional periodicity in a uniaxial field and a rotating field in a horizontal plane. Under a constant pressure and temperature, Monte Carlo simulation has been carried out; phase transitions are found and chainlike structure for a uniaxial field and monolayer or multilayer for rotating field are obtained, which are well consistent with experiments.
RELATIONSHIP BETWEEN CHAIN STRUCTURES AND VISCOSITY IN THE MAGNETO-RHEOLOGICAL SUSPENSIONS STABLE DISPERSING DIFFERENT CONCENTRATION OF IRON PARTICLES WITH SMECTITE
Authors: SHIBAYAMA A. , MIYAZAKI T. , OTOMO T. , FUJITA T. , SHIMADA K.
Published: August 2002

Different concentration of spherical iron particles (7 to 8 μm) are dispersed in silicone oil to increase the stability with smectite. The concentration of iron particles is maintained between 2 and 40 volume %. The solenoid coil surrounding the cylinders applies the magnetic field in the longitudinal direction of cylinder, when the cylindrical viscometer is employed. As the magnetic field increases, the diameter of chain structure also increases. The shear stress versus shear rate is proportional relation since the viscosity enlarges as the magnetic field increases at small concentration of iron in MR fluid. Additionally, the more increase of the magnetic field strength caused the decrease of the shear stresses at large concentration of iron in MR fluid, while the share rate is increased for the open system of the cylinders. It is assumed that wider clusters or wider chain structures are partly produced in the cylinder under the certain magnetic field. Therefore, the shear stress is not uniformly increased. On the other hand, when the cone and plate viscometer is used, the magnetic field direction is perpendicular to the flow direction. The shear stress versus share rate behaves like a Bingham fluid type under the effect of the magnetic field. As increasing the iron particles volume %, the chain structures cannot increase and make other ring type structures. When the magnetic field is measured by hall probe, the magnetic field decreased at some amount of volume percentage of iron suspension because of shield effect.
EFFECT OF RARE EARTH SUBSTITUTION ON ELECTRORHEOLOGICAL PROPERTIES OF TiO2
Authors: ZHAO X. P. , YIN J. B. , XIANG L. Q. , ZHAO Q.
Published: August 2002

This paper describes a new class of water-free electrorheological (ER) fluids based on nonaqueous doped TiO 2 with rare earth (RE) in silicone oil. The thermal character and crystal structure of these materials are investigated with DSC, TG and XRD. The doped TiO 2 crystals possess anatase phase and their lattice spacing varies significantly with the content of rare earth. The rheological measurements show that the doped TiO 2 ER fluid exhibits an obviously higher shear stress than that of pure TiO 2 ER fluid under dc electric field. Especially, substitution with 10mol% cerium or 8mol% lanthanum for Ti can obtain a relatively high shear stress. On the basis of dielectric and conduction measurements, we preliminarily discuss the influence of the doping of rare earth on ER effects of TiO 2.
ELECTRORHEOLOGICAL EFFECT IN SUSPENSIONS OF AgI/Ag2O/V2O5/P2O5 GLASSES
Authors: OSUCHOWSKI MARCIN , PŁOCHARSKI JANUSZ
Published: August 2002

The ER effect results from bulk and surface electric polarization processes in solid grains of ER suspensions but detailed mechanisms are not very clear. The aim of the present study was to find correlations between the character of bulk charge transport processes (electronic and/or ionic) in particles of a dispersion and parameters of the ER effect. As the dispersed phase we used glasses comprising oxides of silver, vanadium and phosphorus with addition of silver iodide. Bulk electric properties of this material could be modified without changing other properties influencing the ER effect like porosity, shape of grains, hardness, affinity to a liquid matrix etc. Variations of concentration of the components result in changes of ionic and electronic conductivity whilst other properties remain constant. The suspensions of the powdered glasses showed relatively high ER effect. The dynamic yield stress figured from 35 to 160 Pa at 2.0kV/mm for 12% concentration by volume. The highest values were observed for ionically conducting samples. The values of relaxation frequencies ( f R ) based on bulk properties of the glass sample were calculated and correlated with the yield stress whose maximum was obtained for samples of f R close to 100 kHz. High ER effect was observed also for samples of f R in the MHz range but in this case different polarization mechanism was postulated. The influence of polarization mechanisms on rheological behavior of the prepared fluids was discussed.
PROTEIN-Fe MR FLUID AND ITS PROPERTIES
Authors: HU LIN , CAI SHAOHONG , ZHANG CHAOPING
Published: August 2002

The MRF consisted of protein-Fe particles prepared by micro emulsion technique has been studied. The process of protein-Fe preparation and its characterization with XRD, SEM and IR analysis are reported. The magnetorheological and temperature effects, as well as sedimentation stability of protein-Fe MRF have been investigated. The results show that the protein-Fe particles are composite of crystalline α-Fe coated with non-crystalline protein. The protein-Fe MR fluid has strong magnetorhological effect, while its sedimentation stability is much improved comparing to that of carbonyl iron MRF.
MAGNETOSTRICTIVE PHENOMENA IN MAGNETORHEOLOGICAL ELASTOMERS
Authors: GINDER J. M. , CLARK S. M. , SCHLOTTER W. F. , NICHOLS M. E.
Published: August 2002

A host of fascinating and useful magnetic phenomena are found in composites containing magnetizable particles in viscoelastic solids. Embedding magnetically soft iron particles in natural rubber produces a class of magnetostrictive composites sometimes termed magnetorheological (MR) elastomers. We have previously shown that these materials can exhibit viscoelastic moduli that increase substantially in an applied magnetic field. In this paper, we incorporate MR elastomers in a simple resonant structure called a tuned absorber to measure the complex dynamic shear moduli of these materials at high frequencies. We find that the fluid-induced modulus increase in MR elastomers is substantial even at kilohertz mechanical frequencies. As in previous measurements at low frequencies, the moduli are generally found to decrease with strain amplitude. We also report preliminary measurements of the relatively large elongation of these materials in applied magnetic fields.
THE DYNAMICS OF MAGNETORHEOLOGICAL ELASTOMERS STUDIED BY SYNCHROTRON RADIATION SPECKLE ANALYSIS
Authors: SCHLOTTER W. F. , CIONCA C. , PARUCHURI S. S. , CUNNINGHAM J. B. , DUFRESNE E. , DIERKER S. B. , ARMS D. , CLARKE R. , GINDER J. M. , NICHOLS M. E.
Published: August 2002

We introduce a new technique for probing the microscopic relaxation of magneto-viscoelastic materials consisting of magnetic particles embedded in a natural rubber matrix. Transversely coherent x-rays from a high brilliance synchrotron source are scattered by the magnetic particles, forming a speckle pattern at low scattering angles. The time dependence of this pattern is recorded with a CCD area detector while the sample is cyclically perturbed by a reversal of the magnetic field direction. The corresponding time-resolved scattering pattern probes both the dynamics of the particles and the relaxation of the matrix in which they are embedded. X-ray photon correlation spectroscopy (XPCS) reveals characteristic time scales for this relaxation by applying the intensity auto-correlation function to the time dependent speckle pattern. For low angle scattering, the wave vector dependence of the relaxation rate exhibits power law length scaling.
Electroviscoelastic Properties in ER Gel of Disperse System under DC Electric Field
Authors: HANAOKA R. , TAKATA S. , FUJITA H. , FUKAMI T. , SAKURAI K. , ISOBE K. , HINO T.
Published: August 2002

The silicone oil-based electrorheological (ER) gel containing the non-aqueous fine particles was newly created in the present study. After these particles were dispersed at 30wt.% in the dimethylsilicone oil, the ER gel was produced by the hydrosilylation reaction in the mixture of the modified silicone oil. The reaction could considerably be promoted by heating at 90°C.

The behavior of particles in the ER gel was observed by a microscopical method. When an electric field was applied to the ER gel, the gap between the electrodes was bridged by the chains of particles arranged in the direction of the electric field. The dynamic properties of the ER gel were also examined under the applied dc electric field up to 2kV/mm using the oscillating rheometer with the low frequencies of 1Hz or less. Consequently, it is shown that the electroviscoelastic effect of the gel can be controlled by the electric field strength.
SOFT GELS WITH ORDERED IRON PARTICLES: FABRICATION AND ELECTRORHEOLOGICAL RESPONSE
Authors: AN YUXIAN , LIU BO , SHAW MONTGOMERY T.
Published: August 2002

For a number of years we and others have investigated electrorheological (ER) gel systems comprising low-modulus elastomers mixed with various particles. Unlike ER fluids, the particles in gels do not change relative positions, thus creating model systems that can be used to check equilibrium theories of ER response. To make such materials, a magnetic field was used to align iron particles during the cure of a liquid silicone prepolymer in a sheet mold. Particle chains were made with as little as 0.5% particles, and aligned at angles from 0 to 45° to the normal. The gap between the particles was controlled by swelling the crosslinked material with additional prepolymer. The dependence of the ER effect on particle structuring in these materials was investigated experimentally using rheometry and dielectrometry. Also investigated were the properties of these materials as transducers and actuators.
A NEW ORGANIC/INORGANIC HYBRID WITH HIGH ELECTRORHEOLOGICAL ACTIVITY
Authors: ZHAO X. P. , DUAN X.
Published: August 2002

In-situ sol-gel method to prepare colloidal hybrids of surfactant modified polysucchride and titanium oxide has been presented, and experiments indicated these highly ER active particles exhibited a remarkable ER effect. The static shear stress can be up to 37 k Pa (shear rate 5 S -1) under DC field of 4 kV/mm at root temperature, well above that of simple blends of starch and TiO 2. In the meanwhile, temperature dependence and sedimentation stability were also greatly improved. Based on recent experimental facts, we find that dielectric properties and surface (interface) activity are two necessary conditions fulfilling the requirement of high ER activity. Adequate grinding of particles with oil can effectively enhance the shear stress, which may be owed to the decline of the activation energy needed for restructuring. It has provided us a new horizon for preparation of excellent ER materials and further studies should be continued to make.
INFLUENCE OF SURFACTANTS ON PROPERTIES OF ELECTRORHEOLOGICAL FLUIDS CONTAINING POLYANILINE
Authors: BOCIŃSKA MAŁGORZATA , WYCIŚLIK HENRYK , OSUCHOWSKI MARCIN , PŁOCHARSKI JANUSZ
Published: August 2002

Sedimentation which is a natural process in most of ER fluids can be reduced by addition of surfactants that influence also other properties of the fluids. To study both the ER effect and the rate of sedimentation was the aim of the investigations. The ER fluids comprised powdered polyaniline and silicone oil to which surfactants of different polarity were added. The rate of sedimentation was measured by a sedimentation balance. The flow curves were recorded under electric field up to 2.5 kV/mm. Current density was also measured as a function of shear rate. It was found that the activity of a surfactant depends strongly on its polarity. The lipophylic surfactants stabilized the suspension very well but about 30% decrease of the dynamic yield stress was observed. The current density was reduced as well by almost one order of magnitude. The hydrophylic surfactants hardly stabilized the suspension but increase of yield stress was observed that was not followed by increase of current density. The role of different types of non-ionic surfactants was discussed.
REVERSIBILITY OF THE ER EFFECT IN IMMISCIBLE LIQUID BLENDS
Authors: YAMAMOTO SHUHEI , MASUBUCHI YUICHI , TAKIMOTO JUN-ICHI , KOYAMA KIYOHITO
Published: August 2002

Blends of immiscible liquids with different dielectric constants and viscosities were known to show the ER effect due to the change of the domain structure by the electric field. One of the major problems of this type of ER fluids is that the stress does not drop to the original value even long after the removal of the field. In this paper, we report on our attempts to improve the reversibility of the ER effect in immiscible blends.
NOVEL ELECTRORHEOLOGICAL MATERIALS WITH TERNARY BLENDS CONTAINING POLYETHERS AND URETHANES
Authors: MINAGAWA KEIJI , KANNO TETSUO , OKAMURA HIROKAZU , MORI TAKESHI , MASUDA SEIZO , TAKAGI HIDENAO , KOYAMA KIYOHITO , TANAKA MASAKI
Published: August 2002

Ternary ER blends composed of two different liquids and solid dispersoid were prepared by blending silicone oil, viscous polyether liquid, and urethane powder at various compositions. The polyether liquid used here was polytetramethylene glycol modified with phenyl isocyanate, and the powder was urethane derivative of 4,4'-diphenylmethane diisocyanate. Under certain conditions, some of the ternary blends showed larger increase of viscosity under an electric field than those of binary mixtures prepared from each component of the ternary one. In this case, the viscous polyether and urethane powder act cooperativity by forming some particular structures within the blends. Microscopic observation revealed that each urethane particle was covered with polyether liquid in the absence of electric field, and that the binary droplets aggregated to form viscous bridges between the electrodes keeping powders within them.
EFFECT OF SURFACE MODIFICATION OF COLLOIDAL SILICA ON ELECTRORHEOLOGICAL PROPERTIES
Authors: GEHIN C. , PERSELLO J.
Published: August 2002

Electrorheological (ER) effect of surface modified silica particles dispersed in silicone oil was experimentally studied. Monodispersed silica particles were prepared by hydrolyzing tetraethylorthosilicate in an ethanol solution. Rheometry measurements of shear stress and viscosity under shear rates of the suspensions were carried out with a rotational double concentric rheometer. Electric field is applied transverse to the direction of the shear. Flow curves reveals that there is no field effect on dispersion of dried particles. When water is adsorbed on the silica particles surface, the ER effect exists, but beyond a rate of 5 wt% of water, the capillary forces produce the aggregation of the particles. This agrees with the theory where it has been shown that the ER behaviour is proportional to the dielectric constant of the particles. Moreover hydrated lithium cations adsorbed on the silica surface involve a reversible ER effect with short relaxation times.
ELECTRORHEOLOGY OF POLYANILINE-COATED POLY(METHYLMETHACRYLATE) MICROSPHERE SUSPENSIONS IN SILICONE OIL
Authors: CHOI HYOUNG J. , CHO YUN H. , CHO MIN S. , JHON MYUNG S.
Published: August 2002

Electrorheological (ER) suspensions containing spherical-monodispersed polymer particles in silicone oil were investigated. The core was poly(methylmethacrylate) (PMMA), obtained by dispersion polymerization method, and the shell, coated on monodisperse PMMA particles, was polyaniline(PA) prepared by in-situ polymerization of aniline in aqueous acidic medium. Both steady shear and dynamic tests were conducted under various electric field strength and particle concentrations in order to study flow and viscoelastic properties of the PAPMMA based ER fluids. Dielectric spectra of the ER fluids obtained were found to given a clue both to analyze their electrical polarization properties and to interpret flow behavior of the PAPMMA ER fluids.
SYNTHESIS AND ELECTRORHEOLOGY OF MESOPOROUS PARTICLS SUSPENSIONS
Authors: CHOI HYOUNG J. , CHO MIN S. , AHN WHA-SEUNG
Published: August 2002

Electrorheological (ER) properties of a fluid composed of mesoporous MCM-41 particles suspended in silicone oil under high electric field were investigated. Typical properties of ER fluids such as viscosity enhancement and viscoelasticity under applied electric fields in MCM-41/silicone oil suspensions were observed. In the dynamic and static yield stress measurements, a strain hardening effect was also observed and subsequently confirmed by elasticity measurement as a function of time under a linear viscoelastic condition.
ELECTRORHEOLOGICAL BEHAVIORS OF POLYANILINE-MONTMORILLONITE CLAY NANOCOMPOSITE
Authors: LU JUN , ZHAO XIAOPENG
Published: August 2002

Polyanilline-montmorillonite nanocomposite (PANI-MMT) particles were synthesized by an emulsion intercalation method and characterized by IR, XRD and TEM spectrometry. TEM showed that the particle's size of MMT-PANI particles was about 100 mm. The dielectric constant of PANI-MMT nanocomposite was increased 2.4 times than that of MMT and 7 times than PANI, the conductivity of PANI-MMT particles was increased was increased 10 times than that of MMT. Meanwhile, the dielectric loss tangent was also increased about 1.36 times than that of PANI. The electrorheological behaviors of the suspensions of PANI-MMT nanocomposite in silicone oil with a 30% weight fraction were investigated under DC electric fields. In 3 kV/mm DC field at room temperature, the yield stress was 8.26 kPa (shear 5 s -1). In 4 kV/mm DC field, the shear strength was 8.30 kPa (γ = 103.1 s -1, T = 20°C), and much higher than that of pure polyaniline (PANI), montmorillonite (MMT) and mixture of polyaniline with clay (MMT + PANI). The sedimentation experiment showed that the PANI-MMT nanocomposite particles did not deposit during about two months. The relevant influential factors between shear stress and electric fields, between shear stress and shear rate, between shear stress and temperature was also discussed preliminarily. The results showed that the MMT-PANI ER fluid displays a notable ER effect under DC electric field.
Electric-Field Induced Formation of Superconducting Granular Balls
Authors: Tao R. , Xu X. , Lan Y. C.
Published: August 2002

When a strong electric field is applied to a suspension of micron-sized high T c superconducting particles in liquid nitrogen, the particles quickly aggregate together to form millimeter-size balls. The balls are sturdy, surviving constant heavy collisions with the electrodes, while they hold over 106 particles each. The phenomenon is a result of interaction between Cooper pairs and the strong electric field. The strong electric field induces surface charges on the particle surface. When the applied electric field is strong enough, Cooper pairs near the surface are depleted, leading to a positive surface energy. The minimization of this surface energy leads to the aggregation of particles to form balls.
GRANULAR FLOW IN THE PRESENCE OF AN ELECTRIC FIELD
Authors: LU KUNQUAN , CHEN WEI , HOU MEIYING , JIAN ZEHUI
Published: August 2002

The granular flow in a vertical pipe in the presence of electric field E is studied. Depending upon its initial state and the applied field voltage the controlled flow rate remains in two phases, dilute flow or dense flow. For dilute flow, the electric field has no effect on the flow rate until V reaches a critical value V 1. At V = V 1, the flow rate drops abruptly and a transition of the particulate from dilute to dense flow occurs. For dense flow, the flow rate decreases monotonically with increasing V. A two-dimensional computer simulation has been done and the results agree qualitatively well with the experimental measurements.
ER PROPERTIES AND FLOW-INDUCED MICROSTRUCTURES OF AN ER FLUID BETWEEN TWO PARALLEL DISK ELECTRODES IN SQUEEZE FLOW MODE
Authors: NAKANO M. , NAGATA T.
Published: August 2002

When an electrorheological fluid between two parallel disk electrodes is subjected to squeeze mode excitation, the microstructural flow behavior of the ER fluid has been investigated in close relation to the measured electrorheological properties. A dilute anhydrous ER fluid made of 10 vol% carbonaceous particles dispersed in silicone oil and two ITO glass disk electrodes are used to visualize the microstructural flow behavior. The squeeze tests are carried out on a mechanical testing machine in tensile, compression and oscillatory squeeze modes. The ER properties and the associated flow-induced microstructures are measured and visualized for different initial DC electric field strengths and initial gap hi = 0.5 mm between the electrodes in two different configurations: (a) the fluid is placed only between the electrodes (conf-1) and (b) the two electrodes are immersed in the ERF (conf-2).
THE SIGNIFICANCE OF FLOW-MODIFIED PERMITTIVITY: A NEW MODEL AND COMPUTER SIMULATION OF ELECTRORHEOLOGY
Authors: HU YUE , LIN EE-YENN E. , DASSANAYAKE UJITHA M.
Published: August 2002

We propose a model that takes into account the effect of flow-modified permittivity on electrorheology (ER). Due to dielectric relaxation, a shear flow causes the induced particle dipole moments in an ER fluid to tilt in a direction away from the direction of the applied DC electric field. Results from our computer simulation indicate that at high shear rates this misalignment (tilt angle) between the particle dipole moments and the applied electric field plays a crucial role in producing ER effects. By choosing particle-fluid dielectric and conductive mismatches to optimize the tilt angle, our simulation produces ER effects at much higher shear rates than those in earlier simulation work, even though there is no chain structure at these high shear rates. The increase in shear stress due to the applied electric field in our simulation is nearly constant over the wide range of shear rates examined, in qualitative agreement with experimental results. In addition, our model generates results that agree with earlier simulation work at low shear rates, where the particle dipole moments are essetially aligned with the field and the chain model is adequate.
RELAXATION THEORY FOR DYNAMIC ELECTRORHEOLOGICAL EFFECT
Authors: GU G. Q. , YU K. W. , HUI P. M.
Published: August 2002

We present a model to investigate the induced interaction between rotating particles in ER fluids. For particle undergoes uniform rotation or harmonic oscillation, the effects due to dipole relaxation are studied analytically. The induced interaction between particles which are rotating uniformly is derived. The result shows that the dynamic effect reduces the interaction between particles. A proof on the consistency of the relaxation equation with charge conservation upon rotation is also given.
NEGATIVE VISCOSITY INDUCED IN A FERROMAGNETIC COLLOIDAL SYSTEM SUBJECTED TO BOTH EXTERNAL SHEAR FLOW AND AC MAGNETIC FIELDS
Authors: MORIMOTO HISAO , MAEKAWA TORU
Published: August 2002

We investigate numerically the effect of an external ac magnetic field on the rheological characteristics of a ferromagnetic colloidal system which is subjected to a shear flow field. We carry out Brownian dynamics simulations, in which both translational and rotational motions of ferromagnetic particles are taken into account. The nondimensional parameters, which govern the problem, are the ratio of the magnetic dipole energy to thermal energy, λ, the ratio of the interactive energy between the magnetic field and the dipole moment to thermal energy, ξ, and the ratio of the shear rate to the viscosity, Pe, which is called the Peclet number. We analyse the dependence of the apparent viscosity on the frequency of the external magnetic field for λ = 1.5, ξ = 2 and Pe = 1. We find that when λ is as small as 1.5, in which case large clusters are not formed in the system, the apparent viscosity increases at low frequencies and becomes almost zero at high frequencies. The viscosity starts decreasing and becomes negative at intermediate frequencies.