bluuebunny/crossref_metadata_2025 huggingface dataset:
Swelling Interaction, Plasticization, and Antioxidant Extraction between Fiber Optic Cable Gels and Polyolefins
Authors: Risch Brian G.
Published: July 2004

The effects of various waterblocking gels are investigated in relation to swelling behavior of polyolefins. Gel absorption is studied in polyethylene and polypropylene/ethylene copolymers as a function of temperature for a density range of 0.868 g/cc to 0.948 g/cc for polyethylene and 0.88 to 0.91 g/cc for propylene/ethylene copolymers. The effect of swelling on antioxidant extraction is also studied as a function of antioxidant molecular weight and degree of swelling. Both factors show a strong influence on the amount of antioxidant extracted. A direct correlation is found between antioxidant extraction by gels and reduction in thermo-oxidative stability.
Effect of Absorption in Aqueous and Hygrothermal Media on the Compressive Properties of Glass Fiber Reinforced Syntactic Foam
Authors: Karthikeyan C. S. , Kishore  , Sankaran S.
Published: July 2004

Absorption due to immersion in aqueous media consisting of either saline or seawater or due to exposure to water vapor conditions and the attendant effect on the compressive properties of syntactic foam reinforced with E-glass fibers in the form of chopped strands were studied. Whereas the compressive strength decreased in samples exposed to water vapor, the saline or seawater immersed samples showed increase when compared to the dry sample. The decrease in strength in the vapor-exposed case is ascribed to higher absorption of water and to debonding and damaged features for interfaces. The enhancement of strength values for the samples immersed in saltish media is traced to the larger size of the chloride ion and resultant changes in the stress state around the fiber-bearing regions. Recourse to an analysis of scanning electron microscopic pictures of the compression-failed samples is taken to explain the observed trends.
Fracture Toughness Variations of Injection Molded Long Fiber Reinforced Thermoplastics
Authors: Gonzalez Fernando , Chassapis Constantin
Published: July 2004

The fracture toughness, defined as Kc, of injection molded long fiber reinforced polypropylene with 50% E-glass and its variations is investigated. Rectangular plaques of different thicknesses at various sets of processing conditions have been fabricated. In order to assess the spatial variation of the fracture toughness, specimens aligned in the direction of the injection molding flow and perpendicular to it, have been obtained and tested at pre-selected locations. The morphology of the samples consisting of flow induced through-thickness layers was also evaluated experimentally and related to the fracture toughness, thus showing the effect of the part morphology on such mechanical property.
Design and Analysis of Crosshead Annular Die for Braided Medical Tubing Extrusion
Authors: Guo Xiaoping , Stehr Richard E.
Published: July 2004

A theoretical method is proposed for optimum design of a crosshead annular die used for medical tubing. According to this method, the geometric variables are determined to minimize the change in gapwisely-averaged flow velocities due to the variation in flow patterns inside the transitional region of the flow channel of the die, namely the gum space. To achieve this, a numerical approach to flow analysis is put forward based upon the simplified motion and energy equations as well as the approximation of the flow channel using a series of varying annular slits, each having constant geometric parameters. Accordingly, the numerical schemes for flow analysis and design optimization are established, and the computer program is developed using Microsoft Visual C++ 6.0. For an optimum die design, the heat adhesion between the cold-fed inner tube and the hot melt during the over-extrusion is evaluated based upon the temperature rise and pressure profile of the melt in the die land. Based upon the optimum die design obtained from the method, the flow is well balanced with enhancement of extrusion quality. Also, it is found that the optimum die designs are less sensitive to extrusion conditions within a certain range.
Fatigue Damage and Life Prediction of Glass/Vinyl Ester Composites
Authors: Kim Ho Sung , Zhang Jianping
Published: July 2004

Fatigue mechanisms and life time prediction of E-glass/vinyl ester composites are studied. Unnotched unidirectional composites subjected to tension-tension sinusoidal loading with a frequency of 1.5 Hz were employed. Quantitative damage data were obtained and analysed for the fatigue life prediction. S-N data and curve were constructed and fatigue mechanisms at different stress ranges were discussed in terms of stiffness reduction/fatigue modulus and quantitative damage. It was found that the micro-crack density increased logarithmically with increasing number of loading cycles. A model based on the fatigue modulus reduction was developed to predict an S-N curve using phenomenological parameters. The life time predictions were shown to be in good agreement with experimental results.
The Hydraulic Permeability of Dual Porosity Fibrous Media
Authors: Markicevic B. , Papathanasiou T. D.
Published: July 2004

We present a computational analysis of viscous flow through arrays of fiber bundles using the Boundary Element Method (BEM) implemented on a multi-processor computer. Up to 700 individual fibers are included in each simulation. These are simple but not trivial models for fibrous preforms used in composites manufacturing-dual porosity systems characterized by different inter- and intra-tow porosities. The way these porosities affect the hydraulic permeability of a preform is currently unknown and is elucidated through our simulations. Numerical results are compared to analytical models. Through a large number of simulations we construct a master curve for the permeability of arrays of fiber bundles for various packing arrangements.
An Elastic-Plastic Stress Analysis of Metal-Matrix Composite Beam Loaded Transversely
Authors: Sayman O.
Published: July 2004

An elastic-plastic stress analysis has been carried out in a stainless steel fiber reinforced aluminum matrix composite beam. The beam is loaded by a single force at its free end. The composite material is assumed perfectly plastic to simplify the investigation. An exact solution is given for the elastic and elastic-plastic regions. Orientation angles of the fiber are chosen as 0°, 30°, 45°, 60° and 90°. The plastic zone expands at the upper side of the beam more than at the lower side for 30°, 45° and 60° orientation angles. Residual stress components of σ x and τ xy are found in the sections of the beam. The plastic collapse occurs at the different points for the beam of 0°, 30°, 45°, 60° and 90° orientation angles.
Effect of Weaving on the Tensile Properties of Carbon Fibre Tows and Woven Composites
Authors: Lee B. , Leong K. H. , Herszberg I.
Published: July 2004

Tension tests were conducted on (consolidated) tow and woven carbon/epoxy composites in an attempt to quantify the effect of fibre damage induced during weaving on the mechanical performance of fibre tows and their corresponding composites. Two commercially-available carbon fibres were considered. The tension tests were carried out on composites with fibre tows sampled from different locations in the loom setup. These included samples from the tensioning, heddles and reed regions of loom setup. In addition, samples were taken from the external (or, surface) and internal warp layers of the woven preforms. The present work has shown that the tensile properties of fibre composites are detrimentally affected only if the fibres suffer sufficiently large amounts of damage during the weaving process. Compared with unidirectional, non-woven fibre tow composites, further deterioration in properties is expected in multilayer woven composites due to the inevitable presence of fibre crimping.
First Ply Failure Analysis of Laminated Panels Under Transverse Loading
Authors: Prusty B. G. , Satsangi S. K. , Ray C.
Published: July 2004

The present investigation deals with the failure analysis of the weakest ply in a laminated composite plate or shell using the method of finite elements. The objective of the study is to detect the stress level at the stage of initiation of damage in the composite panels. An eight noded isoparametric quadratic shell element has been used applying first order shear deformation theory. The elegance of the present formulation lies in the capability of analysing plate as well as shallow and deep shell using a single formulation. Various failure criteria have been studied to predict the load when the weakest lamina fails under transverse static load. The investigation has been made on various plates and shells having varying lamination schemes. Published results on first ply failure analysis of laminated plates are scanty, however the results on laminated shells are not available in the literature. A number of problems on laminated plates have been solved and the results are compared with those available in the relevant literature. A parametric study has been carried out in the present investigation to predict the failure load of laminated shells.
Investigating the Effects of Anisotropy of Knitted Fabric Reinforced Polymer (KFRP) Composite
Authors: Lim C. T. , Ramakrishna S. , Ong L. B. , Huang Z. M.
Published: July 2004

This paper investigates the mechanical performance of Knitted Fabric Reinforced Polymer (KFRP) composite when subjected to tensile loading. In particular, the effects of the fabric orientation (anisotropy) and temperature are examined. Polypropylene (PP) is used for the matrix, while plain weft knitted Kevlar 29 fiber fabric is used for the reinforcement. Tensile tests are conducted at both room and elevated temperatures. The deformation of the KFRP composite when subjected to tensile loading is observed to be distinctly ductile and predominantly plastic. While the tensile modulus is observed to decrease from the wale direction to a minimum between 45° and 60° with respect to the wale direction before increasing slightly towards the course direction, the ultimate tensile strength is observed to decrease from the wale direction to a minimum at the course direction. There are three different modes of failure which can be defined at the wale, 45° and course directions. Failure at other orientations is found to be a combination of any of these three modes of failure.
Cellulose Fibers/Polyethylene Hybrid Composites: Effect of Long Chain Organic Acid Cellulose Esters and Organic Peroxide on Rheology and Tensile Properties
Authors: Jandura Peter , Kokta Bohuslav V. , Riedl Bernard
Published: July 2004

Composites were prepared by compounding linear low-density polyethylene (LLDPE) with cellulose fibers as reinforcing filler. Effect of a small addition of unsaturated or saturated long chain organic acid cellulose esters (cellulose undecylenate, undecanoate, oleate, stearate) with partial degrees of substitution and the presence of dicumyl peroxide (DCP) as a polymer crosslinking initiator was investigated on the rheological and tensile properties of hybrid composites. No grafting of polyethylene onto fibers surfaces occurred under processing conditions; however composites with DCP showed significant increase in tensile properties. The use of unsaturated cellulose esters in composites containing DCP was more effective in maintaining stress at yield and in progressive increase of energy to yield with higher cellulose esters content and degree of substitution in comparison with composites containing only cellulose fibers. The tensile properties decreased sharply in composites containing saturated cellulose esters.
Parametric Resonance Characteristics of Laminated Composite Doubly Curved Shells Subjected to Non-Uniform Loading
Authors: Sahu S. K. , Datta P. K.
Published: July 2004

The parametric resonance characteristics of laminated composite doubly curved panels subjected to various in-plane static and periodic compressive edge loadings, including partial and concentrated edge loading are studied using finite element analysis. The first order shear deformation theory is used to model the doubly curved panels, considering the effects of transverse shear deformation and rotary inertia. The theory used is the extension of dynamic, shear deformable theory according to the Sander’s first approximation for doubly curved laminated shells, which can be reduced to Love’s and Donnell’s theories by means of tracers. The effects of number of layers, static load factor, side to thickness ratio, shallowness ratio, boundary conditions, degree of orthotropy, ply orientations and various load parameters on the principal instability regions of doubly curved panels are studied in detail using Bolotin’s method. Quantitative results are presented to show the effects of shell geometry, lamination details and load parameters on the stability boundaries. Results of plates and cylindrical shells are also presented as special cases and are compared with those available in the literature.
Progressive Fracture of Stitched Stiffened Composite Shear Panels in the Postbuckling Range
Authors: Huang Dade , Minnetyan Levon
Published: July 2004

Progressive damage and fracture of stitched J-stiffened composite panels under shear loading is evaluated via computational simulation. The objective of this paper is to demonstrate the postbuckling range application of a new methodology that scales up constituent material properties, stress and strain limits to the structure level, to evaluate the overall damage and fracture propagation for stitched laminates. Stiffened panels with different lay-up configurations are simulated for various damage stages, including damage initiation, growth, accumulation, and progression to fracture. Postbuckling analysis is also included to evaluate progressive fracture characteristics after local buckling of the skin. Results are compared with experimental data from the literature.
A Study of Buckling of Near Surface Local Delamination in a Cylindrical Laminated Shell
Authors: Wang Xi , Xiao D. G.
Published: July 2004

In this paper, an energy method is applied to study the buckling problem of near surface triangular, elliptical and lemniscated delamination in a cylindrical laminated shell. The relationships between critical strain value and the geometrical and physical parameters of base laminated shell and sub-laminated shell are investigated.
Further Investigation of the Effect of Elongational Viscosity on Entrance Flow
Authors: Sarkar Debabrata , Gupta Mahesh
Published: July 2004

A new model for strain-rate dependence of elongational viscosity of a polymer is introduced. The proposed model can capture the initial strain thickening, which is followed by a descent in elongational viscosity as the elongation rate is further increased. Effect of the four rheological parameters in the new model on a 4:1 entrance flow is analyzed. It is confirmed that the entrance pressure loss and recirculating vortices in an entrance flow grow significantly as the Trouton ratio is increased. The center-line velocity near the abrupt contraction in a 4:1 entrance flow is found to overshoot its value for a fully developed flow in the downstream channel, if the Trouton ratio has a local minima beyond the Newtonian limit of the polymer.
Transient Dynamics of Thick Skew Sandwich Laminates Under Thermal/Mechanical Loads
Authors: Makhecha D. P. , Patel B. P. , Ganapathi M.
Published: July 2004

This paper deals with the prediction of transient dynamic responses of thick skew sandwich plates using C 0 QUAD-8 finite element based on a realistic higher-order theory developed recently. The formulation accounts for the variation of the transverse displacement through the thickness, and abrupt discontinuity in slope of the in-plane displacements at any interface. The governing equations obtained using Lagrange’s equations of motion are solved employing the direct integration technique. The significance of retaining various higher-order terms in the present model is brought out through the numerical problems. A detailed parametric study is also carried out considering the influences of skew angle and thickness ratio on the dynamic characteristics of sandwich laminates subjected to thermal and mechanical loads.
Compressive Behavior and Fracture Features of Rubber Bearing Glass-Epoxy Composites Exposed to Aqueous Media
Authors: Kishore  , Maiti A.
Published: July 2004

Epoxy systems containing HTBN rubber material and reinforced with E-glass fibres, exposed to a fixed time duration in three separate media were subjected to compressive mode of deformation. The yield stress and fractographic features noted on the compression failed samples are reported in this work. The experiment reveals that the seawater exposed sample exhibits a drop in strength compared to dry (unexposed) sample. This kind of drop is maintained if the media is changed from seawater to distilled water. When HCl is included in seawater, the experiment shows a small rise in strength value. These changes have been attributed to various factors like medium ingress into samples assisting interface failure, the larger-sized Cl- influencing the extent of diffusion of medium into system and finally their participation in the deformation phenomena. The fractographic features reveal interface separations that show either scattered debris or a cleaner surface or display a whitish-coated matrix region depending on whether the tests are done on unexposed samples or on ones following the immersion in the media.
Self-Strengthening Research of Fiber Reinforced Pressure Vessel with Metallic Liners
Authors: Wang X. , Li M. D. , Yu Z. Y.
Published: July 2004

On the basis of an elasto-plastic analytical solution for laminating structure, making use of automatic dynamic increment nonlinear finite element analysis software ADINA [1], the self-strengthening research of a FRP (fiber reinforced pressure) vessel with metallic liner is presented in this paper. A self-strengthening pressure is determined to make the aluminum inner layer elastic deformation under hydrostatic pressure and to obtain the best ratio of the vessel’s volume and weight. Thus, the gas-tightness and fatigue strength of FRP vessel were improved. In addition, the influence of thermal load on the vessel was also calculated.
Effect of Water Absorption on the Impact Response of Carbon-Epoxy System Containing Buffer Strips
Authors: Kishore  , Khan Bijoysri , Viswanath B.
Published: July 2004

Instrumented impact testing has been used to evaluate the influence of moisture on the impact resistance of Carbon-Epoxy (C-E) system with buffer strips (BS) incorporated into the laminated composite. Impact tests were done with BS bearing strips posited within the lay-up right below the loading point in one case and away from it in the other. The extent of water ingress was found to increase with increase in the number of BS insertions. While the energy absorption values in plain samples subjected to impact after immersion in water were higher than the corresponding tests on dry samples that for the BS bearing gave varied results depending on the number of BS and their location vis-à-vis the loading point during impact event. The maximum load recorded by various samples, on the other hand, show a general decrease for the water ingressed test coupons. As regards the ductility index values for different set of samples, generally stating, the water immersed BS bearing samples tended to yield lower values.
Eph Receptors, Ephrins, and Synaptic Function
Authors: Murai Keith K. , Pasquale Elena B.
Published: July 2004

Compelling new findings have revealed that receptor tyrosine kinases of the Eph family, along with their ephrin ligands, play an essential role in regulating the properties of developing mature excitatory synapses in the central nervous system. The cell surface localization of both the Eph receptors and the ephrins enables these proteins to signal bidirectionally at sites of cell-to-cell contact, such as synapses. Eph receptors and ephrins have indeed been implicated in multiple aspects of synaptic function, including clustering and modulating N-methyl-D-aspartate receptors, modifying the geometry of postsynaptic terminals, and influencing long-term synaptic plasticity and memory. In this review, we discuss how Eph receptors and ephrins are integrated into the molecular machinery that supports synaptic function.
Intrinsic Regenerative Ability of Mature CNS Neurons
Authors: Chuckowree Jyoti A. , Dickson Tracey C. , Vickers James C.
Published: July 2004

A prevailing view in neuroscience is that the mature CNS has relatively little capacity to respond adaptively to injury. Recent data indicating a high degree of structural plasticity in the adult brain provides an impetus to reexamine how central neurons react to trauma. An analysis of both in vivo and in vitro experimental studies demonstrates that certain brain neurons may have an intrinsic ability to respond to structural injury by an attempt at regenerative sprouting. Indeed, aberrant sprouting following neuronal injury may be the cause of epilepsy following brain trauma and may underlie the neuronal changes stimulated by plaque formation in Alzheimer’s disease. An understanding of the stereotypical reaction to injury of different CNS neurons, as well as the role of nonneuronal cells, may provide new avenues for therapeutic intervention for a range of neurodegenerative diseases and “acquired” forms of CNS injury.
Signaling Cascades Regulating NMDA Receptor Sensitivity to Ethanol
Authors: Ron Dorit
Published: July 2004

One of the major targets for ethanol (alcohol) in the brain is the N-methyl-D-aspartate (NMDA) receptor, a glutamate-gated ion channel. Intriguingly, the effects of ethanol on the NMDA receptor are not homogeneous throughout the brain. This review focuses on recent studies revealing molecular mechanisms that mediate the actions of ethanol on the NMDA receptor in different brain regions via changes in NMDA receptor phosphorylation and compartmentalization. Specifically, the role of the scaffolding protein RACK1 and the regulatory protein DARPP-32 in mediating the distinct effects of ethanol is presented.
Neuroanatomical Markers for Dyslexia: A Review of Dyslexia Structural Imaging Studies
Authors: Eckert Mark
Published: July 2004

A neuroanatomical description of dyslexia has been elusive, due in part to the complex cognitive nature of dyslexia. People with dyslexia have varying degrees of impairment in reading skills that engage oral and written language (reading) neural networks. Although findings for the inferior parietal lobule, inferior frontal gyrus, and cerebellum have been relatively consistent across studies, these studies also demonstrate that anatomical patterns of results vary according to the reading skills that characterize dyslexia. The number and likelihood of atypical anatomical findings in oral and/or written language systems appears to be related to the pattern of impairments in measures of phonology, orthography, and fluency. A comprehensive neurobiological understanding of dyslexia will depend on studies of dyslexic individuals with homogeneous perceptual, cognitive, and genetic backgrounds.
Mapping Changes in the Human Cortex throughout the Span of Life
Authors: Sowell Elizabeth R. , Thompson Paul M. , Toga Arthur W.
Published: July 2004

In this review, the authors summarize the literature on brain morphological changes that occur throughout the human life span from childhood into old age. They examine changes observed postmortem and in vivo where various brain MRI analytic methods have been applied. They evaluate brain changes observed with volumetric image analytic methods and voxel-based morphometric methods that may be used to better localize where changes occur. The primary focus of the review is on recent studies using state-of-the-art cortical pattern-matching techniques to assess age-related changes in cortical asymmetries, gray matter distribution, and brain growth across various age spans. The authors attempt to integrate findings from the in vivo studies with results from postmortem studies and analyze the complicated question of when brain maturation stops and brain aging begins. Analyzing the regional patterns of change initiated at various ages may help elucidate relationships between changing brain morphology and changing cognitive functions that occur throughout life. Long-range longitudinal studies, correlations between imaging and postmortem data, and more advanced image acquisition and analysis technologies will be needed to fully interpret brain morphological changes observed in vivo in relation to development and aging.
First-Trimester Sonographic Signs of Trisomy 13
Authors: Mcshane Cyrethia A.
Published: July 2004

First-trimester screening with or without biochemistry is often thought of as a screening test for high-risk patients and those of advanced maternal age. It is a useful screening tool that is being offered more frequently to the low-risk population. This case demonstrates the sonographic findings associated with Trisomy 13 in a low-risk patient during her first trimester of pregnancy and the evolution of these findings throughout gestation. It also stresses the importance of evaluating fetal anatomy during scans performed in the first trimester, as the clinical management of the patient will be quite different for those with fetal anomalies than those without.
Sonographic Signs of Midgut Malformations Due to Ventral Wall Defects
Authors: Stephenson Susan Raatz
Published: July 2004

The primitive gut begins development within the fourth week of gestation. Embryonic folding toward the midline results in the fusion of the abdominal wall on the midline. Fusion failure results in an abdominal defect that allows the abdominal organs to protrude into the amniotic fluid either with or without a covering membrane. Prenatal testing includes determining the levels of •-fetoprotein (MS-AFP) and acetylcholinesterase (AChE) with abnormal levels raising suspicion for congenital defects of the brain, spine, or abdomen. Sonography is a valuable tool in diagnosing abdominal wall defects as an isolated defect or part of a syndrome.
Urokinase-deficient and urokinase receptor-deficient mice have impaired neutrophil antimicrobial activation in vitro
Authors: Gyetko Margaret R , Aizenberg David , Mayo-Bond Laura
Published: July 2004

Leukocytes express both urokinase-type plasminogen activator (uPA) and the urokinase receptor (uPAR, CD87). We have shown that neutrophil recruitment to the lung during P. aeruginosa pneumonia is impaired in uPAR-deficient (uPAR−/−) mice but is normal in uPA−/− mice. However, both uPA−/− mice and uPAR−/− mice have impaired lung clearance of P. aeruginosa compared with wild-type (WT) mice. To determine the role of uPA and uPAR in antibacterial host defense, we compared neutrophil bacterial-phagocytosis, respiratory burst, and degranulation among uPA−/−, uPAR−/−, and WT mice. Nutrophil phagocytosis was significantly diminished comparing uPA−/− and uPAR−/− mice with WT mice at all time points. The generation of superoxide by both uPA−/− and uPAR−/− neutrophils was about half of that seen in WT neutrophils. Degranulation of azurophilic granules was significantly diminished in uPA−/− neutrophils compared with either uPAR−/− or WT neutrophils. By contrast, agonist-stimulated release of specific granules was not diminished in either uPA−/− or uPAR−/− mice compared with WT. We conclude that the uPA/uPAR system modulates several of the crucial steps in neutrophil activation that result in bacterial killing and effective innate host defense.
Changes to peptide structure, not concentration, contribute to expansion of the lowest avidity cytotoxic T lymphocytes
Authors: Leggatt Graham R , Narayan Sharmal , Fernando Germain J P , Frazer Ian H
Published: July 2004

The efficient in vitro expansion of antigen-specific CD8+ cytotoxic T lymphocytes (CTL) for use in adoptive immunotherapy represents an important clinical goal. Furthermore, the avidity of expanded CTL populations often correlates closely with clinical outcome. In our study, high-avidity CTL lines could be expanded ex vivo from an antigen-primed animal using low peptide concentration, and intermediate peptide concentrations favored the generation of lower avidity CTL. Further increases in peptide concentration during culture inhibited the expansion of all peptide-specific CD8+ cells. In contrast, a single amino acid variant peptide efficiently generated functional CTL populations at high or low peptide concentration, which responded to wild-type epitope with the lowest average avidity seen in this study. We propose that for some peptides, the efficient generation of low-avidity CTL responses will be favored by stimulation with altered peptide rather than high concentrations of wild-type epitope. In addition, some variant peptides designed to have improved binding to major histocompatibility complex class I may reduce rather than enhance the functional avidity for the wild-type peptide of ex vivo-expanded CTL. These observations are relevant to in vitro expansion of CTL for immunotherapy and strategies to elicit regulatory or therapeutic immunity to neo-self-antigen when central tolerance has eliminated high-avidity, cognate T cells.
Involvement of multiple P2Y receptors and signaling pathways in the action of adenine nucleotides diphosphates on human monocyte-derived dendritic cells
Authors: Marteau Frédéric , Communi Didier , Boeynaems Jean-Marie , Suarez Gonzalez Nathalie
Published: July 2004

Adenosine 5′-triphosphate (ATP), which is released from necrotic cells, induces a semimaturation state of dendritic cells (DC), characterized by the up-regulation of costimulatory molecules and the inhibition of proinflammatory cytokines. This action is mediated by cyclic adenosine monophosphate (cAMP) and involves the P2Y11 receptor. As DC express the ecto-enzyme CD39, which converts ATP into adenosine 5′-diphosphate (ADP), the effects of adenine nucleotides diphosphates on molecular signaling [intracellular calcium ([Ca2+]i), cAMP, extracellular signal-regulated kinase 1 (ERK1)], costimulatory molecule expression (CD83), and cytokine production [interleukin (IL)-12, tumor necrosis factor α (TNF-α), IL-10] were investigated in human monocyte-derived DC. ADP, 2-methylthio-ADP, and ADPβS had no effect on cAMP, increased [Ca2+]i, and stimulated the phosphorylation of ERK1. The effect on ERK1 was inhibited by AR-C69931MX, a P2Y12 and P2Y13 antagonist. On the contrary the effect on [Ca2+]i was neither inhibited by AR-C69931MX or by the P2Y1 antagonist MRS-2179. Both effects were inhibited by pertussis toxin. ADPβS alone was less potent for up-regulation of CD83 than ATPγS and did not increase the CD83 expression by DC stimulated with lipopolysaccharide (LPS). Similar to ATPγS, ADPβS inhibited the release of IL-12p40, IL-12p70, and TNF-α stimulated by LPS (1–100 ng/ml). The inhibitory effect of ADPβS on IL-12 release was neither reversed by AR-C69931MX or by MRS-2179. The two nucleotides had opposite effects on IL-10 production: inhibition by ADPβS and potentiation by ATPγS. In conclusion, ATP can modulate the function of DC, directly via a cAMP increase mediated by the P2Y11 receptor and indirectly via its degradation into ADP, which acts via Gi-coupled receptors coupled to ERK activation and calcium mobilization. These distinct mechanisms converge on the inhibition of inflammatory cytokine production, particularly IL-12, but have a differential effect on IL-10.
Heme oxygenase 1 expression induced by IL-10 requires STAT-3 and phosphoinositol-3 kinase and is inhibited by lipopolysaccharide
Authors: Ricchetti Giuseppe A , Williams Lynn M , Foxwell Brian M J
Published: July 2004

Heme-oxygenase 1 (HO-1) is a stress-response protein with anti-inflammatory activity. This study has examined the regulation of HO-1 expression by the anti-inflammatory factor, interleukin (IL)-10 and whether HO-1 could account for the function of the cytokine. IL-10-induced expression of HO-1 required the activation of signal transducer and activator of transcription (STAT)-3 but not p38 mitogen-activated protein kinase. However, expression of HO-1 also required the activation of the phosphatidylinositol-3 kinase pathway, a signaling mechanism not required for the anti-inflammatory activity of IL-10. Moreover, induction of HO-1 expression was not restricted to IL-10, as IL-6, a cytokine known to activate STAT-3, could also induce the protein. In human macrophages, lipopolysaccharide inhibited HO-1 expression induced by IL-10 Also, inhibition of HO-1 activity by the specific inhibitor zinc-II-protoporphyrin-IX had no effect on the anti-inflammatory function of IL-10. In summary, although IL-10 does regulate HO-1 expression, it does not appear to play a significant role in the anti-inflammatory activity of the cytokine.
Structure and regulation of the neutrophil respiratory burst oxidase: comparison with nonphagocyte oxidases
Authors: Quinn Mark T , Gauss Katherine A
Published: July 2004

Neutrophils play an essential role in the body's innate defense against pathogens and are one of the primary mediators of the inflammatory response. To defend the host, neutrophils use a wide range of microbicidal products, such as oxidants, microbicidal peptides, and lytic enzymes. The generation of microbicidal oxidants by neutrophils results from the activation of a multiprotein enzyme complex known as the reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, which is responsible for transferring electrons from NADPH to O2, resulting in the formation of superoxide anion. During oxidase activation, cytosolic oxidase proteins translocate to the phagosome or plasma membrane, where they assemble around a central membrane-bound component known as flavocytochrome b. This process is highly regulated, involving phosphorylation, translocation, and multiple conformational changes. Originally, it was thought that the NADPH oxidase was restricted to phagocytes and used solely in host defense. However, recent studies indicate that similar NADPH oxidase systems are present in a wide variety of nonphagocytic cells. Although the nature of these nonphagocyte NADPH oxidases is still being defined, it is clear that they are functionally distinct from the phagocyte oxidases. It should be noted, however, that structural features of many nonphagocyte oxidase proteins do seem to be similar to those of their phagocyte counterparts. In this review, key structural and functional features of the neutrophil NADPH oxidase and its protein components are described, including a consideration of transcriptional and post-translational regulatory features. Furthermore, relevant details about structural and functional features of various nonphagocyte oxidase proteins will be included for comparison.
Sorting soluble tumor necrosis factor (TNF) receptor for storage and regulated secretion in hematopoietic cells
Authors: Gao Ying , Hansson Markus , Calafat Jero , Tapper Hans , Olsson Inge
Published: July 2004

Hematopoietic cells contain secretory lysosomes that degranulate at sites of inflammation. We envisage that secretory granules can act as vehicles for targeting inflammatory sites, including malignancies, and thereafter, locally release therapeutically active agents to these sites. Exogenous proteins, such as the soluble tumor necrosis factor receptor 1 (sTNFR1), have been shown previously to be targeted to secretory lysosomes [1]. In this work, we asked whether exogenous, secretory lysosome-targeted proteins were subject to regulated secretion. sTNFR1–transmembrane (tm)–cytosol-sorting signal (Y) and sTNFR1–tm–Y–enhanced green fluorescent protein (egfp) were expressed in rat basophilic leukemia cell clones having different secretory capacities. sTNFR1–tm–Y was targeted directly from the Golgi to secretory lysosomes, followed by generation of membrane-free sTNFR1, whose secretion could be triggered by a Ca2+ ionophore or immunoglobulin E receptor activation. In contrast, sTNFR1–tm–Y–egfp was targeted to the plasma membrane and then subjected to endocytosis and presumably, secretory lysosome targeting, as judged by results from antibody ligation and cell-surface biotinylation. Activation of protein kinase C with phorbol ester promoted ectodomain shedding at the cell surface, resulting in sTNFR1 release from sTNFR1–tm–Y–egfp. These results support a concept for using the storage organelles of hematopoietic cells as vehicles for targeting sites of inflammation with therapeutically active agents.
Selective loss of imprinting in the placenta following preimplantation development in culture
Authors: Mann Mellissa R. W. , Lee Susan S. , Doherty Adam S. , Verona Raluca I. , Nolen Leisha D. , Schultz Richard M. , Bartolomei Marisa S.
Published: July 2004

Preimplantation development is a period of dynamic epigenetic change that begins with remodeling of egg and sperm genomes, and ends with implantation. During this time, parental-specific imprinting marks are maintained to direct appropriate imprinted gene expression. We previously demonstrated that H19 imprinting could be lost during preimplantation development under certain culture conditions. To define the lability of genomic imprints during this dynamic period and to determine whether loss of imprinting continues at later stages of development, imprinted gene expression and methylation were examined after in vitro preimplantation culture. Following culture in Whitten's medium, the normally silent paternal H19 allele was aberrantly expressed and undermethylated. However, only a subset of individual cultured blastocysts (∼65%) exhibited biallelic expression, while others maintained imprinted H19 expression. Loss of H19 imprinting persisted in mid-gestation conceptuses. Placental tissues displayed activation of the normally silent allele for H19, Ascl2, Snrpn, Peg3 and Xist while in the embryo proper imprinted expression for the most part was preserved. Loss of imprinted expression was associated with a decrease in methylation at the H19 and Snrpn imprinting control regions. These results indicate that tissues of trophectoderm origin are unable to restore genomic imprints and suggest that mechanisms that safeguard imprinting might be more robust in the embryo than in the placenta.
Interactions between Fat and Dachsous and the regulation of planar cell polarity in theDrosophila wing
Authors: Matakatsu Hitoshi , Blair Seth S.
Published: July 2004

It was recently suggested that a proximal to distal gradient of the protocadherin Dachsous (Ds) acts as a cue for planar cell polarity (PCP) in the Drosophila wing, orienting cell-cell interactions by inhibiting the activity of the protocadherin Fat (Ft). This Ft-Ds signaling model is based on mutant loss-of-function phenotypes, leaving open the question of whether Ds is instructive or permissive for PCP. We developed tools for misexpressing ds and ft in vitro and in vivo, and have used these to test aspects of the model. First, this model predicts that Ds and Ft can bind. We show that Ft and Ds mediate preferentially heterophilic cell adhesion in vitro, and that each stabilizes the other on the cell surface. Second, the model predicts that artificial gradients of Ds are sufficient to reorient PCP in the wing; our data confirms this prediction. Finally,loss-of-function phenotypes suggest that the gradient of dsexpression is necessary for correct PCP throughout the wing. Surprisingly,this is not the case. Uniform levels of ds drive normally oriented PCP and, in all but the most proximal regions of the wing, uniform dsrescues the ds mutant PCP phenotype. Nor are distal PCP defects increased by the loss of spatial information from the distally expressed four-jointed (fj) gene, which encodes putative modulator of Ft-Ds signaling. Thus, while our results support the existence of Ft-Ds binding and show that it is sufficient to alter PCP, ds expression is permissive or redundant with other PCP cues in much of the wing.
Sorption of fission product radionuclides,137Cs and90Sr, by Savannah River Site sediments impregnated with colloidal silica
Authors: Hakem N. , Apps John A. , Moridis G. J. , Al Mahamid I.
Published: July 2004

Permeation grouting with colloidal silica gel is a potentially effective means for creating hydraulic barriers to prevent the advective migration of radioactive contaminants in shallow permeable sediments. However, the effectiveness of silica gel grouted barriers in controlling transport of fission product radionuclides through sorption and diffusion is unknown. To resolve this question, static-batch sorption measurements with Cs+and Sr2+were conducted at ambient temperature (23 °C) and for times up to 96 days on silica gel and on two kaolinitic sediments from the Savannah River Site in South Carolina. Sorption experiments on the latter were conducted both in the presence and in the absence of silica gel. Cesium and strontium concentrations were varied between 10-3to 10-8M (mol/L) and 10-4to 10-8M, respectively. The pH values after one day varied for each experiment and ranged from 3.6 to 6.6. The pH of the solutions were, however, buffered by the sediments and/or silica gel, and changed little over the duration of the experiments. The fraction of both cesium and strontium retained on the solids increased with decreasing radioelement concentration. The sorption data were fitted to the Freundlich isotherm model.
Early Stages of Film Formation and Surface Growth on Tin Electrodes at Bicarbonate Medium: a Modelistic Approach
Authors: Bonilla S. H. , Giannetti B. F.
Published: July 2004

A modelistic approach of the early stages of film formation and surface growth on tin electrodes at bicarbonate medium under dynamic conditions is presented. The modelistic treatment was applied to both anodic and cathodic processes. In order to organise the paper, the potential interval of interest was divided into two potential windows, each one involving one of the anodic peaks and their corresponding cathodic counterparts. The Müller–Calandra model (also known as the layer-pore resistance model) was considered suitable to interpret the film growth processes occurring during the positive scan. A derivation of the former, developed by Devilliers et al., which take into account the conductive electrical nature of the surface compound, was applied to explain the reduction of the film formed within the first potential window. On the other hand, it was verified that the use of a simple model to interpret the cathodic process occurring at the second potential window was not possible due to the complex nature of the process. In this case, a mixed control kinetics was proposed and the current was considered as the sum of two contributions. In order to complement the description and specially to determine the role of diffusion and mass transport in film formation, rotating disk measurements were also carried out.
Lagrange and Hamilton Integrals and their Connection
Authors: Dickel Gerhard
Published: July 2004

The object of the following is the change from Lagrange line integrals of single particles to Lagrange line integrals of systems of particles under the condition of the first law. The first problem is the historical variational principle as imagined by Bernoulli, whereas the second problem concerns the built up of thermodynamic systems from elementary integrals. Since thermodynamics disregards mechanisms governing the connection or the interaction of particles the built up of thermodynamic systems is possible if Lagrange integrals exhibiting addition theorems between the limits are taken into account.

Hilbert’s Independence Theorem involving the transition from the Lagrange to the Hamilton potential proved to be a suitable method to turn over from the mathematical Lagrange potentials to the Hamilton representation as used in physics. Caratheodory, basing his “Complete Figures of Calculus of Variation” on Hilberts conception has given the variational principle that minimizes the connection of the elementary Lagrange integrals being connected between the limits.

The extension of thermodynamics to integrals composed from components showing a connection between the limits yields important thermodynamic properties.
Archaeological Perspectives on Native American Fisheries of California, with Emphasis on Steelhead and Salmon
Authors: Gobalet Kenneth W. , Schulz Peter D. , Wake Thomas A. , Siefkin Nelson
Published: July 2004

The archaeological record of California was surveyed to gain an understanding of Native American fisheries and to locate the prehistoric distributions of freshwater and anadromous fishes. Over 152,000 piscine elements were added to prior totals. On San Francisco Bay, important prehistoric intertidal fisheries were especially well documented for bat rays Myliobatis californica, sturgeons Acipenser spp., Chinook salmon Oncorhynchus tshawytscha, clupeids, and atherinopsids. The same sites also indicate the former presence of various freshwater species, including steelhead O. mykiss and coho salmon O. kisutch, in tributary streams from which they were extirpated prior to modern surveys. Slow‐moving waters of the Central Valley were heavily exploited, with most sites dominated by Sacramento perch Archoplites interruptus, thicktail chub Gila crassicauda, Sacramento suckers Catostomus occidentalis, Sacramento blackfish Orthodon microlepidotus, hitch Lavinia exilicauda, and tule perch Hysterocarpus traski, which collectively comprised 84.9% of the remains. Sacramento perch alone produced 45.7% of the identifiable elements. Noteworthy among the other identified species was the endangered delta smelt Hypomesus transpacificus. Salmonids Oncorhynchus spp. constituted only 6.3% of the remains from the Central Valley, despite their importance in the ethnographic record. Marine fishes were found far from the coast in San Diego, Monterey, and Kern counties. Freshwater species transported from the San Joaquin Valley were found as far eastward as San Bernardino County in the Mojave Desert. Steelhead were found among archaeological materials of coastal California as far south as Los Peñasquito Creek in San Diego County, but no salmon remains of any kind were found south of San Francisco. Too little sampling has been completed from coastal sites between San Francisco and Monterey Bay to rule out salmonid presence at locations where habitat was appropriate and where early reports indicated their existence. Chinook salmon were the most abundant salmonid in the Sacramento River drainage. No salmonids were found in the archaeological record in the San Joaquin River drainage south of San Joaquin County. Elements identifiable as either rainbow trout O. mykiss or cutthroat trout O. clarki were found in middens in the Lahontan system and in headwater streams of the Pit River in northeastern California. The rarity of salmonids in archaeological materials suggests that the ethnographic record overstated the importance of salmonids to the Native Americans of California and dramatically understated the importance of the Sacramento perch and its associated fauna.