bluuebunny/crossref_metadata_2025 huggingface dataset:
Activation of inward rectifier K+channels by hypoxia in rabbit coronary arterial smooth muscle cells
Authors: Park Won Sun , Han Jin , Kim Nari , Ko Jae-Hong , Kim Sung Joon , Earm Yung E
Published: November 2005

We examined the effects of acute hypoxia on Ba2+-sensitive inward rectifier K+(KIR) current in rabbit coronary arterial smooth muscle cells. The amplitudes of KIRcurrent was definitely higher in the cells from small-diameter (<100 μm) coronary arterial smooth muscle cells (SCASMC, −12.8 ± 1.3 pA/pF at −140 mV) than those in large-diameter coronary arterial smooth muscle cells (>200 μm, LCASMC, −1.5 ± 0.1 pA pF−1). Western blot analysis confirmed that Kir2.1 protein was expressed in SCASMC but not LCASMC. Hypoxia activated much more KIRcurrents in symmetrical 140 K+. This effect was blocked by the adenylyl cyclase inhibitor SQ-22536 (10 μM) and mimicked by forskolin (10 μM) and dibutyryl-cAMP (500 μM). The production of cAMP in SCASMC increased 5.7-fold after 6 min of hypoxia. Hypoxia-induced increase in KIRcurrents was abolished by the PKA inhibitors, Rp-8-(4-chlorophenylthio)-cAMPs (10 μM) and KT-5720 (1 μM). The inhibition of G protein with GDPβS (1 mM) partially reduced (∼50%) the hypoxia-induced increase in KIRcurrents. In Langendorff-perfused rabbit hearts, hypoxia increased coronary blood flow, an effect that was inhibited by Ba2+. In summary, hypoxia augments the KIRcurrents in SCASMC via cAMP- and PKA-dependent signaling cascades, which might, at least partly, explain the hypoxia-induced coronary vasodilation.
Costameres, focal adhesions, and cardiomyocyte mechanotransduction
Authors: Samarel Allen M.
Published: November 2005

Mechanotransduction refers to the cellular mechanisms by which load-bearing cells sense physical forces, transduce the forces into biochemical signals, and generate appropriate responses leading to alterations in cellular structure and function. This process affects the beat-to-beat regulation of cardiac performance but also affects the proliferation, differentiation, growth, and survival of the cellular components that comprise the human myocardium. This review focuses on the experimental evidence indicating that the costamere and its structurally related structure the focal adhesion complex are critical cytoskeletal elements involved in cardiomyocyte mechanotransduction. Biochemical signals originating from the extracellular matrix-integrin-costameric protein complex share many common features with those signals generated by growth factor receptors. The roles of key regulatory kinases and other muscle-specific proteins involved in mechanotransduction and growth factor signaling are discussed, and issues requiring further study in this field are outlined.
Temporal gradients in shear, but not spatial gradients, stimulate ERK1/2 activation in human endothelial cells
Authors: White Charles R. , Stevens Hazel Y. , Haidekker Mark , Frangos John A.
Published: November 2005

We have previously demonstrated temporal gradients in shear stress stimulate endothelial cell proliferation, whereas spatial gradients do not. In the present study, the extracellular signal-regulated kinases 1 and 2 (ERK1/2) pathway was investigated as a possible mediator for the promitogenic effect of temporal gradients. The sudden expansion flow chamber (SEFC) model was used to differentiate the effect of temporal gradients in shear from that of spatial gradients on ERK1/2 activation in human umbilical vein endothelial cells (HUVEC). ERK1/2 activation in the SEFC was not significantly different from control when HUVEC were exposed to spatial gradients alone. When a single temporal impulse was superimposed on spatial gradients, ERK1/2 activation was stimulated 330% (relative to spatial alone) within the region of spatial gradients. Inhibition of the ERK1/2 pathway with U-0126 abolished all effects of temporal gradients. To further separate temporal and spatial gradients, a conventional parallel plate flow chamber was utilized. Acute exposure to oscillations in flow at a frequency of 1 Hz stimulated ERK1/2 activation 620 ± 88% relative to control, whereas a single impulse of flow increased ERK1/2 activation 166 ± 19%. Flow without the temporal component did not significantly activate ERK1/2. These results suggest that the ERK1/2 pathway directly mediates the promitogenic effects of temporal gradients in shear stress.
Peripherally administered CRF stimulates colonic motility via central CRF receptors and vagal pathways in conscious rats
Authors: Tsukamoto Kiyoshi , Nakade Yukiomi , Mantyh Christopher , Ludwig Kirk , Pappas Theodore N. , Takahashi Toku
Published: November 2005

Corticotropin releasing factor (CRF) is one of the most important factors in the mechanism of stress-induced stimulation of colonic motility. However, it is controversial whether stress-induced stimulation of colonic motility is mediated via central or peripheral CRF receptors. We investigated the hypothesis that peripherally injected CRF accelerates colonic motility through the central CRF receptor, but not the peripheral CRF receptor. A strain gauge transducer was sutured on the serosal surface of the proximal colon. Colonic motility was monitored before and after the peripheral injection of CRF. An in vitro muscle strip study was also performed to investigate the peripheral effects of CRF. Subcutaneous injection of CRF (30–100 μg/kg) stimulated colonic motility in a dose-dependent manner. The stimulatory effect of peripherally administered CRF on colonic motility was abolished by truncal vagotomy, hexamethonium, atropine, and intracisternal injection of astressin (a CRF receptor antagonist). No responses to CRF (10−9 −10−7 M) of the muscle strips of the proximal colon were observed. These results suggest that the stimulatory effect of colonic motility in response to peripheral administration of CRF is mediated by the vagus nerve, nicotinic receptors, muscarinic receptors, and CRF receptors of the brain stem. It is concluded that peripherally administered CRF reaches the area postrema and activates the dorsal nucleus of vagi via central CRF receptors, resulting in stimulation of the vagal efferent and cholinergic transmission of the proximal colon.
Exogenous carbohydrate oxidation rates are elevated after combined ingestion of glucose and fructose during exercise in the heat
Authors: Jentjens Roy L. P. G. , Underwood Katie , Achten Juul , Currell Kevin , Mann Christopher H. , Jeukendrup Asker E.
Published: November 2005

The first purpose of this study was to investigate whether a glucose (GLU) + fructose (FRUC) beverage would result in a higher exogenous carbohydrate (CHO) oxidation rate and a higher fluid availability during exercise in the heat compared with an isoenergetic GLU beverage. A second aim of the study was to examine whether ingestion of GLU at a rate of 1.5 g/min during exercise in the heat would lead to a reduced muscle glycogen oxidation rate compared with ingestion of water (WAT). Eight trained male cyclists (maximal oxygen uptake: 64 ± 1 ml·kg−1·min−1) cycled on three different occasions for 120 min at 50% maximum power output at an ambient temperature of 31.9 ± 0.1°C. Subjects received, in random order, a solution providing either 1.5 g/min of GLU, 1.0 g/min of GLU + 0.5 g/min of FRUC, or WAT. Exogenous CHO oxidation during the last hour of exercise was ∼36% higher ( P < 0.05) in GLU+FRUC compared with GLU, and peak oxidation rates were 1.14 ± 0.05 and 0.77 ± 0.08 g/min, respectively. Endogenous CHO oxidation was significantly lower ( P < 0.05) in GLU+FRUC compared with WAT. Muscle glycogen oxidation was not different after ingestion of GLU or WAT. Plasma deuterium enrichments were significantly higher ( P < 0.05) in WAT and GLU+FRUC compared with GLU. Furthermore, at 60 and 75 min of exercise, plasma deuterium enrichments were higher ( P < 0.05) in WAT compared with GLU+FRUC. Ingestion of GLU+FRUC during exercise in the heat resulted in higher exogenous CHO oxidation rates and fluid availability compared with ingestion of GLU and reduced endogenous CHO oxidation compared with ingestion of WAT.
Determinants of skin sympathetic nerve responses to isometric exercise
Authors: Wilson Thad E. , Dyckman Damian J. , Ray Chester A.
Published: November 2005

Exercise-induced increases in skin sympathetic nerve activity (SSNA) are similar between isometric handgrip (IHG) and leg extension (IKE) performed at 30% of maximal voluntary contraction (MVC). However, the precise effect of exercise intensity and level of fatigue on this relationship is unclear. This study tested the following hypotheses: 1) exercise intensity and fatigue level would not affect the magnitude of exercise-induced increase in SSNA between IHG and IKE, and 2) altering IHG muscle mass would also not affect the magnitude of exercise-induced increase in SSNA. In protocol 1, SSNA (peroneal microneurography) was measured during baseline and during the initial and last 30 s of isometric exercise to volitional fatigue in 12 subjects who randomly performed IHG and IKE bouts at 15, 30, and 45% MVC. In protocol 2, SSNA was measured in eight subjects who performed one-arm IHG at 30% MVC with the addition of IHG of the contralateral arm in 10-s intervals for 1 min. Exercise intensity significantly increased SSNA responses during the first 30 s of IHG (34 ± 13, 70 ± 11, and 92 ± 13% change from baseline) and IKE (30 ± 17, 69 ± 12, and 76 ± 13% change from baseline) for 15, 30, and 45% MVC. During the last 30 s of exercise to volitional fatigue, there were no significant differences in SSNA between exercise intensities or limb. SSNA did not significantly change between one-arm and two-arm IHG. Combined, these data indicate that exercise-induced increases in SSNA are intensity dependent in the initial portion of isometric exercise, but these differences are eliminated with the development of fatigue. Moreover, the magnitude of exercise-induced increase in SSNA responses is not dependent on either muscle mass involved or exercising limb.
Frequency-domain characteristics and filtering of blood flow following the onset of exercise: implications for kinetics analysis
Authors: Ferreira Leonardo F. , Harper Allison J. , Barstow Thomas J.
Published: November 2005

We examined the validity and usefulness of a low-pass filter (LPFILTER) to reduce point-to-point variability and enhance parameter estimation of the kinetics of blood flow (BF). Computer simulations were used to determine the power spectrum of simulated responses. Moreover, we studied the leg BF response to a single transition in four subjects during supine knee-extension exercise using three methods of data processing [beat-by-beat, average of 3 cardiac cycles (AVG3 BEATS), and LPFILTER]. The power spectrum of BF containing the kinetics information (≤0.2 Hz) did not overlap with the oscillations due to muscle contraction and cardiac cycle (simulations and Doppler measurements). There were no significant differences between the parameter estimates for a two-exponential model using Beat-by-Beat, AVG3 BEATS, and LPFILTER ( P > 0.05; n = 4). However, LPFILTER (cutoff = 0.2 Hz) resulted in a significantly lower standard error of the estimate for all parameters ( P < 0.05). The means ± SD for the standard error of the estimate for Beat-by-Beat, AVG3 BEATS, and LPFILTER were, respectively, time constant- phase 1 = 5.0 ± 1.1 s, 4.5 ± 2.1 s, and 0.3 ± 0.2 s; time delay- phase 2 = 17.8 ± 7.9 s, 12.8 ± 7.5 s, and 1.4 ± 1.4 s; time constant- phase 2 = 15.8 ± 4.6 s, 9.9 ± 2.9 s, and 1.1 ± 0.5 s. In conclusion, LPFILTER appeared to be a valid procedure providing a high signal-to-noise ratio and data density and thus LPFILTER resulted in the smallest confidence interval for parameter estimates of BF kinetics.
Spinal Cord Maps of Spatiotemporal Alpha-Motoneuron Activation in Humans Walking at Different Speeds
Authors: Ivanenko Y. P. , Poppele R. E. , Lacquaniti F.
Published: November 2005

Functional MRI (fMRI) imaging of motoneuron activity in the human spinal cord is still in its infancy, and it will remain difficult to apply to walking. Here we present a viable alternative for documenting the spatiotemporal maps of α-motorneuron (MN) activity in the human spinal cord during walking, similar to the method recently reported for the cat. We recorded EMG activity from 16 to 32 ipsilateral limb and trunk muscles in 13 healthy subjects walking on a treadmill at different speeds (1–7 km/h) and mapped the recorded patterns onto the spinal cord in approximate rostrocaudal locations of the motoneuron pools. This approach can provide information about pattern generator output during locomotion in terms of segmental control rather than in terms of individual muscle control. A striking feature we found is that nearly every spinal segment undergoes at least two cycles of activation in the step cycle, thus supporting the idea of half-center oscillators controlling MN activation at any segmental level. The resulting spatiotemporal map patterns seem highly stereotyped over the range of walking speeds studied, although there were also some systematic redistributions of MN activity with speed. Bursts of MN activity were either temporally aligned across several spinal segments or switched between different segments. For example, the center of mass of MN activity in the lumbosacral levels generally shifted from rostral to caudal positions in two cycles for each step, revealing four major activation foci: two in the upper lumbar segments and two in the sacral segments. The results are consistent with the presence of at least two and possibly more pattern generators controlling the activation of lumbosacral MNs.
Dynamics of Pain: Fractal Dimension of Temporal Variability of Spontaneous Pain Differentiates Between Pain States
Authors: Foss Jennifer M. , Apkarian A. Vania , Chialvo Dante R.
Published: November 2005

Spontaneous pain is a common complaint in chronic pain conditions. However, its properties have not been explored. Here we study temporal properties of spontaneous pain. We examine time variability of fluctuations of spontaneous pain in patients suffering from chronic back pain and chronic postherpetic neuropathy and contrast properties of these ratings to normal subjects' ratings of either acute thermal painful stimuli or of imagined back pain. Subjects are instructed to continuously rate their subjective assessment of the intensity of pain over a 6- to 12-min period. We observe that the fluctuations of spontaneous pain do not possess stable mean or variance, implying that these time series can be better characterized by fractal analysis. To this end, we apply time and frequency domain techniques to characterize variability of pain ratings with a single parameter: fractal dimension, D. We demonstrate that the majority of ratings of spontaneous pain by the patients have fractal properties, namely they show a power law relationship between variability and time-scale length; D is distinct between types of chronic pain, and from ratings of thermal stimulation or of imagined pain; and there is a correspondence between D for pain ratings and D for brain activity, in chronic back pain patients using fMRI. These results show that measures of variability of spontaneous pain differentiate between chronic pain conditions, and thus may have mechanistic and clinical utility.
Synchronization in ensembles of coupled maps with a major element
Authors: Omelchenko Iryna , Maistrenko Yuri , Mosekilde Erik
Published: November 2005

The paper investigates the conditions for full and partial
synchronization in systems of coupled chaotic maps that include
the presence of a major element, that is, an element that
interacts with all the other elements of the system. We consider a
system which consists of two globally coupled populations of
one‐dimensional maps that interact via a major element. The
presence of this element can induce synchronization in both of the
globally coupled populations even though they operate in different
states. If a parameter mismatch is introduced between two
populations of uncoupled maps, the presence of a major element is
found to provide for the existence of states in which peripheral
elements with different parameter values display similar dynamics.
Existence and global stability of periodic solution fordelayed discrete high‐order Hopfield‐type neural networks
Authors: Xiang Hong , Yan Ke-Ming , Wang Bai-Yan
Published: November 2005

By using coincidence degree theory as well as a priori estimates
and Lyapunov functional, we study the existence and global
stability of periodic solution for discrete delayed high‐order
Hopfield‐type neural networks. We obtain some easily verifiable
sufficient conditions to ensure that there exists a unique
periodic solution, and all theirs solutions converge to
such a periodic solution.
Adaptive control of single‐input single‐output hybrid systems possessing interacting discrete‐ and continuous‐time dynamics
Authors: de la Sen M.
Published: November 2005

This paper deals with the problem of synthesizing a
robust adaptive controller for a specific class of single‐input
single‐output (SISO) time‐invariant hybrid controlled object
(plant) which can operate under bounded disturbances and/or
unmodeled dynamics. The hybrid plant dealt with is composed of two
coupled subsystems, one of them being of continuous‐time type
while the other is digital. As a result there are also mixed
continuous‐time and discrete signals present in the system
associated either with the solutions of differential equations
which depend at the same time on both discrete‐time and
continuous‐time forcing terms and on generalized
difference equations associated with discretized and digital
signals. The estimation algorithm is of a continuous‐time nature
since the plant parameter estimates are updated for all time. It
also incorporates a relative adaptation dead‐zone as a robust
stabilization mechanism which prevents against instability in the
presence of a common class of unmodeled dynamics and bounded
noise.
Attractors for maps with fractional inverse
Authors: Ferchichi M. R. , Djellit I.
Published: November 2005

In this work, we consider some dynamical properties and specific contact bifurcations of two‐dimensional maps having an inverse with vanishing denominator. We introduce new concepts and notions
of focal points and prefocal curves which may cause and generate new dynamic phenomena. We put in evidence a link existing between basin bifurcation of a map with fractional inverse and the prefocal curve of this inverse.
Constructing complete chaotic maps with reciprocal structures
Authors: Huang Weihong
Published: November 2005

A class of unimodal complete chaotic maps f = {fL, fR}

with reciprocal functional forms (fR = 1/fL)
are
examined. The necessary and sufficient conditions are provided to
construct such maps. The theoretical conclusions are then
verified by numerical simulations.
Fractional hold circuits versus positive realness of discrete transfer functions
Authors: de la Sen M. , Bilbao-Guillerna A.
Published: November 2005

The appropriate use of fractional‐order holds (β‐FROH) of
correcting gains β ∈ [−1, 1]
as an alternative to the
classical zero‐and first‐order holds (ZOHs, FOHs) is discussed
related to the positive realness of the associate discrete
transfer functions obtained from a given continuous transfer
function. It is proved that the minimum direct input/output gain
(i.e., the quotient of the leading coefficients of the numerator
and denominator of the transfer function) needed for discrete
positive realness may be reduced by the choice of β compared
to that required for discretization via ZOH.
Redox-Dependent Transcriptional Regulation
Authors: Liu Hongjun , Colavitti Renata , Rovira Ilsa I. , Finkel Toren
Published: November 2005

Reactive oxygen species contribute to the pathogenesis of a number of disparate disorders including tissue inflammation, heart failure, hypertension, and atherosclerosis. In response to oxidative stress, cells activate expression of a number of genes, including those required for the detoxification of reactive molecules as well as for the repair and maintenance of cellular homeostasis. In many cases, these induced genes are regulated by transcription factors whose structure, subcellular localization, or affinity for DNA is directly or indirectly regulated by the level of oxidative stress. This review summarizes the recent progress on how cellular redox status can regulate transcription-factor activity and the implications of this regulation for cardiovascular disease.
From Karbala to New York City: Taziyeh on the Move
Authors: Chelkowski Peter J.
Published: November 2005

This collection of articles traces Taziyeh from its origins in Karbala in Iraq through its development as a serious dramatic form in Iran; its adaptation in Lebanon, India, and the Caribbean; and its debut on Western stages, culminating in a 2002 performance at Lincoln Center in New York City and a historic symposium at the Asia Society, where this issue got its start. Karbala and the relationship between Shiite and Sunnite Muslims, the origins of which are represented in the plays and rituals that commemorate the death of the Prophet Muhammad's grandson Hussein, have become major preoccupations of the Western media since the U.S.-led invasion of Iraq in March 2003.An examination of Taziyeh reveals many of the historical, cultural, religious, and political paradigms that have made Karbala the touchstone for Shiite Muslims everywhere.
Theatre for the Ballot: Campaigning with Street Theatre in India
Authors: Ghosh Arjun
Published: November 2005

An integral part of political campaigns in India, street theatre is not restricted to parties of any particular ideology; the nature and role of street theatre varies according to different organizational structures and conditions of performance. For political parties it is a mode of reaching out to the electorate at the grassroots level; for spectators it is also a source of entertainment.The author toured with India's foremost street theatre group, the Jana Natya Manch (People's Theatre Forum), during campaigns in Kanpur for the April 2004 Parliamentary elections
Four Thousand Forgotten Generations: The Longue Durée in African History Challenges Mission, Theology and Piety
Authors: Jenkins Paul
Published: November 2005

With a few notable exceptions the history of Christianity in the regions of Black Africa begins around 1800 or later. The bulk of missiological work on the continent naturally concentrates on the 10 generations in which evangelisation has taken place and churches have grown. But the human race has a history of 4–5,000 generations in Africa. Is it possible to build a bridge between the missiological concern with recent Christian history, and the long perspectives which the continent offers the general historian? The author essays a Christian approach to the millennia in which African populations, with little input from outside, have survived by the quality of their knowledge of, and thinking about, their environment – the ability humans always had to observe and to ratiocinate. He argues that over 4–5,000 generations humans in Africa have practised what we call science, interleaved with what we call religion. This view gives missiologists a basis for a positive approach to pre-Christian belief and ritual in Africa, but challenges us also to ask if Christian practice there has paid enough attention to traditional centres of intellectual articulation among its peoples.
A Theological Reflection on 'The Baptism into the Deep' and its Missiological Implications for the Asian Catholic Church
Authors: Fung Jojo
Published: November 2005

This article represents a germinal effort in the field of contextual theology in Malaysia and employs a critical correlation method, facilitating an interface between the indigenous cultures and the Christian faith. At the onset of the theological reflection, this article identifies as its locus theologicus the kenotic experience of 'baptism in the deep' sacred mysteries of life, although this practice has been preceded by other renowned Asian theologians and amongst them, Aloysius Pieris of Sri Lanka no less. This 'epiphanic moment' is made possible through a reputable shaman who ritualized one of the religious beliefs and cultural practices of the Muruts, an indigenous people living near the Southwestern border of Sabah (former British North Borneo) and Northern Kalimantan on the Borneo Island. Yet this baptismal experience is all the more poignant because of the apparent poverty of a believing Murut community who embodies a little known spirituality of the marginalized poor in Asia. For reasons of its social marginality and subliminal sacrality, the corpus of the Muruts' beliefs and practices is described (for want of a better term) in the meantime as the subaltern spirituality of suspect. However, in correlating a context-specific religious experience to the papal teaching Novo Millennio Ineuunte, especially with regard to its underlying mission theology epitomized by the Lucan phrase 'put out in the deep' (Luke 5:4), its inadequacy becomes evident when transposed to Asia, a continent that abounds with pluriform yet distinctive cosmologies, cultures, psychologies and spiritualities. What is proposed as central to 'doing mission' in Asia is a dialogic process that involves a reciprocal mutuality of learning and unlearning, receiving and giving, enriching and critiquing. Resulting from this correlatonal interface is the enumeration of three indispensable criteria (power of distinction, sacrality of the rites of passage, rituals are efficacious), with an additional 5 theological principles (related to creation, Christ, Incarnation, Resurrection, the Spirit and sound fruits) for the re-valuation and evaluation of indigenous shamanism. These foundational principles become crucial for the subsequent explicitation of nine missiological strategies by which the Catholic Church of Asia become more efficacious in its mission amongst the indigenous peoples.
Towards a Functional Christology Among AICs in Ghana
Authors: Clarke Clifton
Published: November 2005

This article explores the means by which Christ is encountered and appropriated in the everyday lives of African Indigenous Church adherents in Ghana. Drawing upon an extensive Christological questionnaire that surveyed 2500 people across the ten regions of Ghana, as well as making use of the ethnographic data gathered through focus groups discussions and interviews, it seeks to understand the way Christology functions in the lives of adherents of AICs in Ghana.The study reveals that Akan AIC experience of Jesus Christ is not one that is confined to personal piety or private devotions but rather one that is shared and experienced in the public arenas of life. It appears that Akan AICs possess a functional Christology that aids life and protects from anti-life forces. They have no concept of a Christology as a mere philosophical or theological construct, they know only how to serve Christ through their daily encounter with Him through daily living. This African functional Christology reminds us that we do not find Christ in the flight of the alone to the Alone, escaping from turmoil to tranquillity, but only in the community of the banalities of ordinary life in which we need others to help us make sense of the meaning and significance of the Christ event.
Effects of Geometrical and Material Features on Damage Onset and Propagation in Single-lap Bolted Composite Joints under Tensile Load: Part I – Experimental Studies
Authors: Riccio A. , Marciano L.
Published: November 2005

An experimental investigation has been carried out in single-lap bolted composite joints in order to point out the influence of geometrical and material characteristics on the damage onset and propagation under tensile loading conditions. Protruding and countersunk joints have been considered, with different bolt diameters and different interfaces (composite-to-composite and composite-toaluminum). First, static tensile tests have been performed on single-lap joints. Then, non-destructive ultrasonic evaluations have been conducted at intermediate load levels and at final failure in order to show the real onset and evolution of damage inside the joints in terms of fibers and matrix breakage.
Moisture Diffusion in a Fiber-reinforced Composite: Part I – Non-Fickian Transport and the Effect of Fiber Spatial Distribution
Authors: Bond David A.
Published: November 2005

The results of an investigation into the effects of non-Fickian sorption and fiber spatial distribution on moisture diffusion in laminated composite materials are presented as part of a study to develop a predictive model for fiber-reinforced composite moisture transport mechanics. Experimental diffusion rate data are obtained from gravimetric analysis of T800/924 carbon fiber epoxy composites using Fickian absorption models adapted to account for hygro-elastic relaxation and polymer–penetrant interaction mechanisms. The transverse diffusion coefficient of the composite (Dz) is determined relative to that of the polymer matrix (Dp) and the ratio Dz/Dp is compared with experimental data provided in other published research. The experimental data, both from this investigation and that obtained from other sources, exhibit significant scatter and only limited correlation with a traditional flux-continuity model. The use of the adapted sorption models reduces experimental scatter by 60% through improved representation of the true sorption mechanics of polymer-based systems. The effects of fiber spatial distribution on the predictions of the flux-continuity model are also considered. There is found to be negligible difference between fully random and, the more commonly assumed and analyzed, regular-packed distributions. A novel finding of the investigation is an assessment of the effect layered high and low fiber volume fraction regions have on the transverse diffusivity of a composite. In such configurations, Dz/Dp is significantly reduced from that predicted using bulk composite properties, providing a possible explanation for the variation between some experimental data and predicted behavior.
The Development of Thermal Stresses in Polyimide Matrix Composite Materials as a consequence of Three-dimensional Thermal Gradients – Analysis and Experiment
Authors: Drukker E. , Kresel I. , Green A. K. , Marom G.
Published: November 2005

Composite material parts may experience service exposure to three-dimensional (3D) temperature gradients where temperature differences may exceed 150 C. The effect of these conditions on a glass fabric-reinforced BMI resin laminate has been analyzed as a function of location using a 3D model. According to analysis predictions, in a situation of thermal load and temperature gradients, compression stresses develop in the center of the heated zone, which is surrounded by a tensile-stressed annular region. The stresses and strains developed are small compared to the ultimate mechanical properties of the material. The analysis has been verified by subjecting an instrumented sample to nonuniform heating. This confirmed that in the absence of absorbed moisture, the damageinducing potential of local heating was small. This observation suggests that less conservative design approaches can be used for thick laminates compared to the current, with a consequent weight saving potential.
Evaluating the Fineness of Agave Americana L. Fibers
Authors: Msahli S. , Ydrean J. , Sakli F.
Published: November 2005

Like all long vegetal fibers, hard or soft, agave Americana L. fibers show greatly dispersed fineness. In this paper, this dispersion is demonstrated using two approaches: measurement of the gravimetric fineness and evaluation of different aspects of diameter.
Effect of Some Variables on Properties of 100% Cotton Vortex Spun Yarn
Authors: Ortlek Huseyin Gazi , Ulku Sukriye
Published: November 2005

This paper examines the influence of various parameters such as delivery speed, nozzle pressures, and yarn count on the properties of vortex yarns produced using a Murata vortex spinning system. The results indicated that the delivery speed, nozzle pressure, and yarn count are all significant parameters for yarn evenness, imperfections, hairiness and tensile properties. Our findings show that increasing the delivery speed increases the hairiness and decreases the number of neps, and the tensile properties of vortex yarns. When the nozzle pressure increases, yarn unevenness, the number of thick places, the neps values, and the tensile properties of vortex yarns increases but the hairiness values of vortex yarns decreases. In general, the physical, the hairiness, and the tensile properties of coarser vortex yarns are better than finer yarns.
Thread Loadings in Different Measuring Positions on the Sewing Machine
Authors: Žunič-Lojen Darja , Geršak Jelka
Published: November 2005

The knowledge of sewing thread tension determined at different measuring locations on the sewing machine is the basis for the definition of the loading magnitudes acting during the stitch formation process and the locations at which they appear, concerning the stitch cycle or the main shaft turn of the sewing machine. During the stitch formation process the sewing thread is exposed to the highest tension in the region between the tension regulator and the thread take-up lever, following by tension in the region between the take-up lever and the needle and in the region in front of the tension regulator. Dynamic tension and tension force are also dependent on stitch velocity.
Process of Complex Core Spun Yarn Containing a Metal Wire
Authors: Lou Ching-Wen
Published: November 2005

Nearly all electrostatic dissipating yarns or fabrics are fabricated from a man-made carbon conducting core surrounded by a sheath of polyester or nylon, electroplated staple fiber, fabric or stainless steel staple fiber. Few electrostatic dissipating materials are spun from continuous, well conducting metal wires. This work uses metal wire as the core and fabricates the yarn using a ring-spinning machine. The copper and stainless steel wires were employed as core materials, and rayon and T/R (polyester/rayon) roving were used as cover materials. During the spinning process, the metal wire was fed from the front rollers and underwent drafted roving to spin yarn with a complex core. The guide device was designed and installed on the roller-weighting arm to increase the stability of spinning of the metal wire. Various parameters such as the core materials, the roving materials, the twist level and the count of the spun yarn were changed to investigate how various parameters affect the tenacity and hairiness of the complex core spun yarn.
Carrier Dyeing of Different Energy Level Disperse Dyes on Polyester Fabric
Authors: Iskender Mustafa A. , Becerir Behcet , Koruyucu Aslihan
Published: November 2005

Carrier dyeing is a method of dyeing polyester materials that is used when necessary. Although usage of carriers in dyeing enables the dyeing of polyester materials at atmospheric pressure, the undesirable properties of the carriers are drawbacks. Disperse dyes are classified under different energy levels and the dyeing methods and color and fastness properties of dyed materials are associated with this classification. Carriers can be used when dyeing at higher temperatures than 100°C to promote the leveling of the more difficult disperse dyes. In the presence of a carrier substance in the dye bath, the dyeing behavior of the disperse dyes may become sensitive to dyeing temperature and dye bath concentration changes. Disperse dyes may show distinct dyeing properties in combination dyeing in carrier dyeing although they belong to the same energy level. Color-matching operations made by using a color-matching software must take the sensitivity of both dye bath concentration and dyeing temperature of the disperse dyes into account in the carrier dyeing of polyester fibers. According to the experimental results obtained on individual disperse dyes in the present study, problems may arise in carrier dyeing of polyester fibers with disperse dyes in combination dyeing because of the different dyeing temperature and dye bath concentration sensitivity of dyes that have the same energy level. Combination dyeing must not be performed close to dyeing temperatures of 100°C when dyeing in the presence of a carrier.
Evaluation of Grid-domed Textile Composite as Shock-absorbing Liner of Bicycle Helmets
Authors: Wong Y. W. , Yu T. X. , Tao X. M.
Published: November 2005

This paper is concerned with a study of the deformation mechanism of a flat-topped, grid-domed textile composite possessing high specific energy absorption capacity. The composite was fabricated by curing thermoset resin-impregnated nylon knitted fabric as a grid-domed cellular structure. During the forming process the fabric stretching may affect the cell wall thickness which is a critical factor on the deformation mode and the global energy absorption capacity. The deformation mechanism of a unit cell was studied under quasi-static axial compression and a modified mechanics model is proposed to describe the large plastic deformation mechanism of the flat-topped, conical cell under axial compression. The potential applications of this textile composite include use as a shock-absorbing liner of bicycle helmets, an energy-absorbing vehicle door or other lightweight devices in which high energy absorption capacity is of great importance.
Torsional Analysis of Fibers with a Generalized Elliptical Cross-section
Authors: Lee Kyung Woo
Published: November 2005

An approximate torsional rigidity constant and a torsional shape factor for fibers with a generalized elliptical cross-section were obtained in the closed form. The Galerkin method was used to solve the torsion problem and Saint-Venant’s approximation formula for torsional rigidity constant was also obtained.
Production of a Polyester Core-Spun Yarn with Spandex Using a Multi-section Drawing Frame and a Ring Spinning Frame
Authors: Lou C. W. , Chang C. W. , Lin J. H. , Lei C. H. , Hsing W. H.
Published: November 2005

Owing to growing demand for figure hugging and comfortable clothes made with stretchable fibers, spandex fibers are being used in underwear, diapers, hosiery, leisurewear, sportswear, jeans, and so on. In the present study a polyester core-spun yarn containing spandex fibers was made using a self-designed, multi-section drawing frame and a ring spinning frame. The mechanical properties of the core-spun elastic yarns were examined in various processing conditions. The analytical results show that when the main drawing ratio of the spandex fibers was either 2.2 or 2.7, the maximum breaking tenacity and elongation of the core-spun elastic yarns exceeded those in any other of the main drawing ratio conditions.
Comfort Properties of Heat Resistant Protective Workwear in Varying Conditions of Physical Activity and Environment. Part II: Perceived Comfort Response to Garments and its Relationship to Fabric Properties
Authors: Yoo Shinjung , Barker Roger L.
Published: November 2005

Controlled garment wear trials are used to evaluate comfort response to a well-characterized set of heat-resistant workwear materials. Multiple categories of perceived comfort reactions to garment wear in diverse conditions are explained in terms of measured fabric properties assessed in Part I. The important role of fabric surface character, especially surface roughness and predicted skin contact area, is revealed. Fabric sweat management, measurable using a modified demand wettability test, is also identified as a useful predictor of moisture-related skin contact sensations. Heat-resistant fabric designs incorporating structural features that minimize skin contact, while also providing liquid absorption capacity, are predicted to show enhanced comfort performance. Blending of hydrophilic fibers and wicking finishes, however, do not necessarily improve the comfort perceptions in the tested scenarios. Selected fabric thermophysiological and sensorial properties are closely correlated with subjective comfort responses and the relationships are dependent on the wear conditions. Surface geometric roughness (SMD), number of contact points ( nk), and bending and shear rigidities are the decisive properties related to the tactile comfort. The vapor buffering index ( Bd) and liquid management properties, such as absorbent capacity ( V), initial rate ( Q1), and wet cling index ( ik) are the correlated indicators of nonabsorbency, clinginess, and sensation of clamminess. In particular, apparent water ratio ( A/ T), which can be assessed by a modified demand wettability test, is a good predictor of perception of clamminess in the cool-down period after exercise or a hot situation.
Sensorial Property Evaluation of Scoured Silk Fabrics Using Quad Analysis
Authors: Kim Jeong-Jin , Yoo Shinjung , Kim Eunae
Published: November 2005

The importance and usefulness of a subjective evaluation of the sensorial properties of scoured silk fabrics is discussed. Silk fabric was treated with 12 different scouring rates and the scoured fabrics were used as specimens. Seven trained subjects, using paired comparisons, evaluated seven subjective sensorial properties. A quad experimental design was adopted for a more effective and reliable evaluation. Objective sensorial properties were assessed by using the Kawabata Evaluation System (KES), and objective measurement and subjective evaluation of sensorial properties were correlated to the scouring rate. The results show that subjects did not recognize the differences in smoothness of the samples, even though the objective measurements demonstrated differences between them. Softness or stiffness, drapability, and luster were closely correlated to the scouring rate, implying that these subjective properties can be effectively manipulated by the scouring process of silk fabrics.
Transport and Mechanical Properties of Polyurethane Film Treated by Ultrasonic Energy
Authors: Park Jung Woo , Jeong Won Young , An Seung Kook , Lee Jae Ho
Published: November 2005

The properties of microporous polyurethane film are mainly determined by the size and distribution of the pores which are microscopic spaces within the polyurethane layer. It is very important for the manufacturer to be able to control the size and shape of the pores. In this study, the probability of controlling the pores was tested by treatment with ultrasonic energy during the coagulation stage. The mechanical and transport properties of film treated by ultrasonic energy were significantly different from those of film made by the normal process. This was due to the subdivision of very large pores within the polyurethane by the ultrasonic treatment and the consequent increase in the number of pores.
An Improved MWK Structure for Composite Reinforcement
Authors: Zhou Rongxing , Hu Hong , Chen Nanliang , Feng Xunwei
Published: November 2005

An improved MWK structure with a double loop pillar stitch is presented in this work. Its structural features, knitting process, and mechanical properties are analyzed and compared with a common tricot MWK structure. The results show that the improved MWK structure with the double loop pillar stitch has better mechanical properties than the common MWK structure with the tricot stitch.
Physiological and Subjective Evaluation of the Rustling Sounds of Polyester Warp Knitted Fabrics
Authors: Cho Gilsoo , Cho Jayoung , Kim Chunjeong , Ha Jiyoung
Published: November 2005

This study evaluates the rustling sounds of polyester warp knitted fabrics using a psychophysiological technique. We generate and record the rustling sounds of three structural types—reverse locknit, double denbigh, and sharkskin—of warp knitted fabrics, all made from 75D polyester filament yarn at the same density. To obtain quantitative information about rustling sounds, Zwicker’s psychoacoustic parameters—loudness( z), sharpness( z), roughness( z), and fluctuation strength( z)—are calculated from sound spectra obtained by FFT analysis. We acquire physiological signals—electroencephalogram, the ratio of low frequency to high frequency (LF/HF) from the power spectrum of heart rate variability, respiration rate (RESP), heart rate (HR)—from fourteen female participants when each sound is presented to them, and they rate seven sensations—softness, pleasantness, comfort, noisiness, annoyance, clearness, and highness—by free modulus magnitude estimation. Loudness( z), roughness( z), and fluctuation strength( z) are highest for the sharkskin and lowest for the reverse locknit. The rustling sound of double denbigh appears to be related to a positive sensation, with the highest softness, pleasantness, and comfort, and the lowest beta wave and LF/HF. On the other hand, the sharkskin sound appears to evoke negative sensations, with the highest annoyance and noisiness and most increasing beta wave, RESP, HR, and LF/HF. Therefore, we conclude that psychoacoustic parameters such as loudness( z), roughness( z), and fluctuation strength( z) affect psychological and physiological responses evoking negative sensations for warp knitted fabric sounds.
Liquid Permeability of an Anisotropic Fiber Web
Authors: Håkanson Johan M. , Toll Staffan , Lundström T. Staffan
Published: November 2005

The Darcian permeability of a dense network of fibers with general orientation is examined experimentally and analytically. The permeability of a carded PA6 fiber web is measured in the three principal directions using a saturated parallel flow technique. A model is introduced that generalizes existing theories for unidirectional fiber arrays to fiber networks of general orientation distribution. The average drag on a given fiber is assumed to be independent of the overall fiber orientation distribution. A second-order orientation tensor describes the orientation dependence. Our generalization applied to the models of Gebart predicts reasonably well the in-plane permeability, but overestimates the out-of-plane permeability by a factor of four.
Characteristics of Cloth Formation in Weaving and Their Influence on Fabric Parameters
Authors: Chen Xiaogang
Published: November 2005

This paper discusses the characteristics of cloth formation in weaving as regards continuous weaving, the concept of balanced weaving is put forward, and an equation of balanced weaving is then established for analyzing the response of the weaving process to disturbances of various kinds. Based on the analysis of beat-up resistance and weft yarn bouncing back, the cloth formation area is defined as an indicator of the weaving conditions. These discussions lead to control of fabric parameters.
Hand-Related Mechanical Behavior of Enzyme-Treated Yarns
Authors: Radhakrishnaiah P. , He Jingwu , Cook Fred L. , Buschle-Diller Gisela
Published: November 2005

In the second part of our two-part study, we attempt to understand the influence of enzyme treatment on the properties of bicomponent yarns that exhibit systematic differences in fiber arrangement within the yarn. Our results show that the treatment alters the properties of a ring spun, random blended, polyester-cotton yarn more than it alters the properties of a corresponding sheath-core yarn. Results also reveal that the treatment has a different influence on the properties of two friction spun cotton-polyester yarns, one made with a staple polyester core and the other with a multifilament polyester core. The weight losses suffered by the treated yarns are also influenced by the fiber arrangements within the yarn.
Predicting the Pilling Propensity of Fabrics through Artificial Neural Network Modeling
Authors: Beltran Rafael , Wang Lijing , Wang Xungai
Published: November 2005

Fabric pilling is affected by many interacting factors. This study uses artificial neural networks to model the multi-linear relationships between fiber, yarn and fabric properties and their effect on the pilling propensity of pure wool knitted fabrics. This tool shall enable the user to gauge the expected pilling performance of a fabric from a number of given inputs. It will also provide a means of improving current products by offering alternative material specification and/or selection. In addition to having the capability to predict pilling performance, the model will allow for clarification of major fiber, yarn and fabric attributes affecting fabric pilling.