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It is established that the human pathogen Legionella pneumophila becomes significantly augmented for infection of macrophages after intracellular growth in amoebae when compared to like-strains cultivated in laboratory media. Based on this observation, we reasoned that the most critical virulence determinants of L.p. are expressed by responding to stimuli generated by the protozoan host specifically; a process we term “protozoan-priming.” We sought to identify L.p. virulence factors that were required for replication in amoebae in order to highlight the genes necessary for production of the most infectious form of the bacterium. Using a transposon mutagenesis screen, we successfully identified 12 insertions that produced bacteria severely attenuated for growth in amoebae, while retaining a functional Dot/Icm type IVb secretion system. Seven of these insertion mutants were found dispensable for growth in macrophages, revealing attractive therapeutic targets that reside upstream of the pathogen-human interface. Two candidates identified, lpg0730 and lpg0122 were required for survival and replication in amoebae and macrophage host cells. Both genes are conserved among numerous important human pathogenic bacteria that can persist or replicate in amoebae. Each gene encodes a component of an ATP binding cassette (ABC) transport complex of unknown function. We demonstrate the lpg0730 ortholog in Francisella tularensis subsp. novicida to be essential for colonization of both protozoan and mammalian host cells, highlighting conserved survival mechanisms employed by bacteria that utilize protozoa as an environmental reservoir for replication.

The alternative sigma factor σE functions to maintain bacterial homeostasis and membrane integrity in response to extracytoplasmic stress by regulating thousands of genes both directly and indirectly. The transcriptional regulatory network governed by σE in Salmonella and E. coli has been examined using microarray, however a genome-wide analysis of σE-binding sites in Salmonella has not yet been reported. We infected macrophages with Salmonella Typhimurium over a select time course. Using chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq), 31 σE-binding sites were identified. Seventeen sites were new, which included outer membrane proteins, a quorum-sensing protein, a cell division factor, and a signal transduction modulator. The consensus sequence identified for σE in vivo binding was similar to the one previously reported, except for a conserved G and A between the -35 and -10 regions. One third of the σE-binding sites did not contain the consensus sequence, suggesting there may be alternative mechanisms by which σE modulates transcription. By dissecting direct and indirect modes of σE-mediated regulation, we found that σE activates gene expression through recognition of both canonical and reversed consensus sequence. New σE regulated genes (greA, luxS, ompA and ompX) are shown to be involved in heat shock and oxidative stress responses.

A cost-effective and efficacious influenza vaccine for use in commercial poultry farms would help protect against avian influenza outbreaks. Current influenza vaccines for poultry are expensive and subtype specific, and therefore there is an urgent need to develop a universal avian influenza vaccine. We have constructed a live bacterial vaccine against avian influenza by expressing a conserved peptide from the ectodomain of M2 antigen (M2e) on the surface of Lactococcus lactis (LL). Chickens were vaccinated intranasally with the lactococcal vaccine (LL-M2e) or subcutaneously with keyhole-limpet-hemocyanin conjugated M2e (KLH-M2e). Vaccinated and nonvaccinated birds were challenged with high pathogenic avian influenza virus A subtype H5N2. Birds vaccinated with LL-M2e or KLH-M2e had median survival times of 5.5 and 6.0 days, respectively, which were significantly longer than non-vaccinated birds (3.5 days). Birds vaccinated subcutaneously with KLH-M2e had a lower mean viral burden than either of the other two groups. However, there was a significant correlation between the time of survival and M2e-specific serum IgG. The results of these trials show that birds in both vaccinated groups had significantly (P

It is established that the human pathogen Legionella pneumophila becomes significantly augmented for infection of macrophages after intracellular growth in amoebae when compared to like-strains cultivated in laboratory media. Based on this observation, we reasoned that the most critical virulence determinants of L.p. are expressed by responding to stimuli generated by the protozoan host specifically; a process we term "protozoan-priming." We sought to identify L.p. virulence factors that were required for replication in amoebae in order to highlight the genes necessary for production of the most infectious form of the bacterium. Using a transposon mutagenesis screen, we successfully identified 12 insertions that produced bacteria severely attenuated for growth in amoebae, while retaining a functional Dot/Icmtype IVb secretion system. Seven of these insertion mutants were found dispensable for growth in macrophages, revealing attractive therapeutic targets that reside upstream of the pathogen-human interface. Two candidates identified, lpg0730 and lpg0122 were required for survival and replication in amoebae and macrophage host cells. Both genes are conserved among numerous important human pathogenic bacteria that can persist or replicate in amoebae. Each gene encodes a component of an ATP binding cassette (ABC) transport complex of unknown function. We demonstrate the lpg0730 ortholog in Francisella tularensis subsp. novicida to be essential for colonization of both protozoan and mammalian host cells, highlighting conserved survival mechanisms employed by bacteria that utilize protozoa as an environmental reservoir for replication. [ABSTRACT FROM AUTHOR]

The alternative sigma factor σE functions to maintain bacterial homeostasis and membrane integrity in response to extracytoplasmic stress by regulating thousands of genes both directly and indirectly. The transcriptional regulatory network governed by σE in Salmonella and E. coli has been examined using microarray, however a genome-wide analysis of σE–binding sites in Salmonella has not yet been reported. We infected macrophages with Salmonella Typhimurium over a select time course. Using chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq), 31 σE–binding sites were identified. Seventeen sites were new, which included outer membrane proteins, a quorum-sensing protein, a cell division factor, and a signal transduction modulator. The consensus sequence identified for σE in vivo binding was similar to the one previously reported, except for a conserved G and A between the -35 and -10 regions. One third of the σE–binding sites did not contain the consensus sequence, suggesting there may be alternative mechanisms by which σE modulates transcription. By dissecting direct and indirect modes of σE-mediated regulation, we found that σE activates gene expression through recognition of both canonical and reversed consensus sequence. New σE regulated genes (greA, luxS, ompA and ompX) are shown to be involved in heat shock and oxidative stress responses. [ABSTRACT FROM AUTHOR]

The extracytoplasmic functioning sigma factor σE is known to play an essential role for Salmonella enterica serovar Typhimurium to survive and proliferate in macrophages and mice. However, its regulatory network is not well-characterized, especially during infection. Here we used microarray to identify genes regulated by σE in Salmonella grown in three conditions: a nutrient-rich condition and two others that mimic early and late intracellular infection. We found that in each condition σE regulated different sets of genes, and notably, several global regulators. When comparing nutrient-rich and infection-like conditions, large changes were observed in the expression of genes involved in Salmonella pathogenesis island (SPI)-1 type-three secretion system (TTSS), SPI-2 TTSS, protein synthesis, and stress responses. In total, the expression of 58% of Salmonella genes was affected by σE in at least one of the three conditions. An important finding is that σE up-regulates SPI-2 genes, which are essential for Salmonella intracellular survival, by up-regulating SPI-2 activator ssrB expression at the early stage of infection and down-regulating SPI-2 repressor hns expression at a later stage. Moreover, σE is capable of countering the silencing of H-NS, releasing the expression of SPI-2 genes. This connection between σE and SPI-2 genes, combined with the global regulatory effect of σE, may account for the lethality of rpoE-deficient Salmonella in murine infection. [ABSTRACT FROM AUTHOR]

A cost-effective and efficacious influenza vaccine for use in commercial poultry farms would help protect against avian influenza outbreaks. Current influenza vaccines for poultry are expensive and subtype specific, and therefore there is an urgent need to develop a universal avian influenza vaccine. We have constructed a live bacterial vaccine against avian influenza by expressing a conserved peptide from the ectodomain of M2 antigen (M2e) on the surface of Lactococcus lactis (LL). Chickens were vaccinated intranasally with the lactococcal vaccine (LL-M2e) or subcutaneously with keyhole-limpet-hemocyanin conjugated M2e (KLHM2e). Vaccinated and nonvaccinated birds were challenged with high pathogenic avian influenza virus A subtype H5N2. Birds vaccinated with LL-M2e or KLH-M2e had median survival times of 5.5 and 6.0 days, respectively, which were significantly longer than non-vaccinated birds (3.5 days). Birds vaccinated subcutaneously with KLH-M2e had a lower mean viral burden than either of the other two groups. However, there was a significant correlation between the time of survival and M2e-specific serum IgG. The results of these trials show that birds in both vaccinated groups had significantly (P < 0.05) higher median survival times than non-vaccinated birds and that this protection could be due to M2e-specific serum IgG. [ABSTRACT FROM AUTHOR]

Phosphate based glasses (PBG) are currently of huge interest in the biomaterials field and findings have shown that their durability can be increased by doping with selected metal cations. In this study various compositions in the system (50-x)Na2O-xCaO-50P2O5 glasses, 0≤x≤50, were investigated to determine their characteristic temperatures (glass transition temperature (Tg), onset and peak temperatures of crystallisation (Tx and Tp), melting point and liquidus temperature (Tm and TJ), and also the temperature dependence of viscosity and density. The glass compositions were confirmed via EDX and the amorphous nature of the glasses was confirmed via XRD. Tg increased with increasing CaO mol% from 280±0⋅5°C to 521±01°C. The temperature dependence of viscosity revealed an increase in the temperature window for extrusion (from 26±0-66°C to 42±0-31°C) and fibre drawing (from 363±1⋅0°C to 539±0⋅9°C). The density was also seen to increase from 2⋅5 to 2⋅64 gcm-3. The increases in properties were attributed to the crosslinking of Ca2+ cations between phosphate chains which strengthened the glass network. For x≤20 mol% the activation energy for viscous flow is affected by the phosphate chain length. For 30≥x≥50 mol% the crosslinking effect of Ca2+ counters the effect of decreasing chain length, resulting in increasing activation energy for viscous flow. [ABSTRACT FROM AUTHOR]

Phosphate glass fiber of the composition 20Na2O-24MgO-16CaO-40P2O5 was produced using an in-house fiber drawing rig. The interfacial properties of the phosphate glass fiber/poly(caprolactone) (PCL) system were measured using the single fiber fragmentation test (SFFT). The system was calibrated using E-glass fibers and polypropylene system. This gave an interfacial shear strength (IFSS) of 4.1 MPa, which agrees well with other published data. The IFSS for the unsized (as drawn) phosphate glass fiber/PCL system was found to be 1.75 MPa. Fibers treated with 3-aminopropyl-triethoxy silane (APS) showed an IFSS of 3.82 MPa. X-ray photoelectron spectroscopic (XPS) analysis of unsized and silane sized fibers established the presence of silane on the fiber surface. Degradation tests of the silane treated fiber/PCL samples were carried out in deionised water at 37°C and it was found that the IFSS values decreased over time. Four others silanes were also investigated but APS gave the highest IFSS values. [ABSTRACT FROM AUTHOR]

We report results from an initial small animal study designed to provide information on the biocompatibility of a novel biodegradable composite designed for craniomaxillofacial reconstruction. Rat calvarium was chosen as a clinically analogous model, which allowed comparison between experimental groups (PCL alone, PCL/phosphate glass, or PCL/bioglass implants) and control groups (empty defects or bone grafted defects). All animals recovered well from surgery and no clinical complications were observed. Histological assessment indicated a lack of inflammatory response. The amount of new bone formation at the dural aspect of the implant was statistically significantly higher in the PCL/phosphate glass group than the other experimental groups. This study confirms, in a clinically analogous model, the promise of the novel PCL/phosphate glass composite material. Work is planned toward manufacturing scale up and clinical trials. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2010. [ABSTRACT FROM AUTHOR]

Poly(caprolactone) matrix iron phosphate glass fiber-reinforced (16Na2O-24MgO-16CaO-4Fe2O3-40P2O5) composites (10% fiber by weight) were fabricated by compression molding. Tensile strength, tensile modulus, elongation at break (%), bending strength, bending modulus and impact strength of the composites were found to be 72 MPa, 2.74 GPa, 11%, 86 MPa, 3.22 GPa and 16 kJ/m2, respectively. Degradation tests of the fibers and composites were performed in aqueous medium at 37°C. Mechanical properties of the composites retained almost 90% of their original properties after 6 months of aqueous degradation. Interfacial shear strength (IFSS) of the composite was also measured by using the single-fiber fragmentation test. The IFSS of the composite system was found to be 4.01 MPa. [ABSTRACT FROM AUTHOR]

We investigate the fabrication of continuous carbon fiber/poly(ε-caprolactone) composites for biomedical applications. Two fabrication methods: in-situ polymerization and film stacking are compared at two different thicknesses. Analysis of void content produced via the two fabrication methods showed that the in-situ polymerization specimens had considerably lower void content than the film stacked samples. Significantly higher mechanical properties were obtained for the in-situ polymerized samples, and an almost three-fold increase in properties was seen as compared to the film stacked samples. Scanning electron microscopy images of surfaces supported the findings above. Dynamic mechanical analysis revealed higher dynamic modulus for the in-situ polymerized samples which was consistent with the above results. [ABSTRACT FROM AUTHOR]

The article explores the kinetics of ε-caprolactone polymerization in the presence of Sn(Oct)2/BF3 dual catalyst. Resuls have demonstrated an induction period for both neat Sn(Oct)2 catalyst and Sn(Oct)2/BF3 dual catalyst, whereas there is no induction period for neat BF3 catalyst. The length of the induction period for the Sn(Oct)2-catalyzed reactions was not affected by the presence of BF3.

Polymers prepared from polylactic acid (PLA) have found a multitude of uses as medical devices. The main advantage of having a material that degrades is so that an implant would not necessitate a second surgical event for removal. In addition, the biodegradation may offer other advantages. In this study, fibers produced from a quaternary phosphate‐based glass (PBG) in the system 50P2O5‐40CaO‐5Na2O‐5Fe2O3 (nontreated and heat‐treated) were used to reinforce the biodegradable polymer, PLA. Fiber properties were investigated, along with the mechanical and degradation properties and cytocompatibility of the composites produced. Retention of mechanical properties overtime was also evaluated. The mean fiber strength for the phosphate glass fibers was 456 MPa with a modulus value of 51.5 GPa. Weibull analysis revealed a shape and scale parameter value of 3.37 and 508, respectively. The flexural strength of the composites matched that for cortical bone; however, the modulus values were lower than those required for cortical bone. After 6 weeks of degradation in deionized water, 50% of the strength values obtained was maintained. The composite degradation properties revealed a 14% mass loss for the nontreated and a 10% mass loss for the heat‐treated fiber composites. It was also seen that by heat‐treating the fibers, chemical and physical degradation occurred much slower. The pH profiles also revealed that nontreated fibers degraded quicker, thus correlating well with the degradation profiles. The in vitro cell culture experiments revealed both PLA (alone) and the heat‐treated fiber composites maintained higher cell viability as compared to the nontreated fiber composites. This was attributed to the slower degradation release profiles of the heat‐treated composites as compared to the nontreated fiber composites. SEM analyses revealed a porous structure after degradation, and it is clear that there are possibilities here to tailor the distribution of porosity within polymer matrices. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [ABSTRACT FROM AUTHOR]

The article discusses a study on the use of 2-Hydroxyethyl methacrylate (HEMA) as coupling agent for phosphate glass fibers (PGF) and to measure the mechanical properties of HEMA-treated fiber reinforced poly(caprolactone) (PCL) matrix unidirectional composites. X-ray photoelectron spectroscopy (XPS) analysis was used to study the chemical environment of the HEMA-treated PGF surfaces. PGF treated with HEMA in methanol solution followed by ultra violet radiation showed lower degradation.

Melt-spun phosphate glass fibres (40 mol% P2O5-20 mol% Na2O-16 mol% CaO-24 mol% MgO) were aged for up to 7 days in doubly distilled water at 37 °C prior to single-fibre tensile testing. The effects of aqueous aging on the evolution of strength and modulus are discussed along with the possibilities for mitigating property loss via surface treatment and annealing. Whilst as-drawn fibres exhibited a strength loss over time, annealing produced a significant increase in strength over the same period. Silane pre-treatment of as-drawn fibres yielded no significant benefit to strength. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare a range of phosphate-based glasses containing a fixed amount of (50 mol%) P2O5 and varying amounts of CaO and Na2O, made using two different sets of precursors in order to investigate any potential differences in their properties. Thermal analysis, XRD, dissolution, EDX, density, H-NMR and ion release studies were conducted in order to compare the data obtained from both groups. Thermal analyses revealed no differences in the glass transition temperatures obtained between the two groups, and similar crystalline phases were identified for each composition from both groups via XRD analysis. However, statistically significant differences were seen between the dissolution rates and density values obtained. The density values increased linearly with increasing CaO content, whilst the degradation rates decreased with increasing CaO content and spanned over four orders of magnitude. A decrease in the release of both cations and anions with increasing CaO content was also observed, with rates also ranging over four orders of magnitude. From the compositions investigated, the largest amounts of ions released were those of the Na+ and Ca2+ ions and the P3O3-9 anion, with higher total anion release observed from glasses prepared from one set of precursors than the other. EDX analysis confirmed the composition of the glass formulations produced and no H+ ions were detected from 1H-NMR analyses conducted, suggesting that no H+ was present in the glass produced. [ABSTRACT FROM AUTHOR]

The article discusses results of a study that evaluates the effect of hydrolysis and plasticization to the flexural modulus of an alipathic polymer. A discussion on the use of Fickian diffusion to characterize the polymer's absorption moisture is given. The study showed changes in the molecular weight of the polymer and the maximum moisture content and diffusivity constant.

Carbon fibre based composite manufacturing processes have been considered for automotive body panel applications. A full scale front wing–fender component was produced using two composite manufacturing processes (a semi impregnated (semi preg) system and a novel directed fibre preforming–resin transfer moulding process) and compared with an existing stamped steel component for mechanical properties, weight saving, and cost, using a technical cost modelling procedure. Mechanical testing demonstrates that the carbon fibre composite solutions can provide 40–50 per cent weight saving for an equivalent bending stiffness to steel panels and greatly improved dent resistance. For the part studied, carbon fibre semi preg systems offered the lowest cost process up to around 500 parts/annum and directed fibre preforming technologies were cheaper between 500 and 9000 parts/annum. The steel component was seen to be more cost effective at volumes above around 9000 parts/annum. [ABSTRACT FROM AUTHOR]

The surface quality of polymer composite laminates was examined via geometric modelling techniques and compared to experimental data. TexGen software provided the platform for the development of a surface roughness simulation tool which accounted for textile architecture and specific cure kinetics of the matrix. The study focused on the influence of thermal and chemical shrinkage during cure and the change in localised volume fraction across the surface of a unit cell. A one-dimensional analysis was used to determine proportional dimensional changes to the matrix region, with the results stitched together to form a three-dimensional topological plot. Three demonstrator geometric models were developed to represent a carbon 2 × 2 twill weave fabric with 3000, 6000 or 12 000 tows. These models were analysed with low and high shrink resin properties. Optical microscopy was used to determine accurate tow forms for compacted tows which aided the development of the geometric model. Simulated profiles, topography and surface roughness measures were compared to experimental data which demonstrated the significance of matrix contraction and fabric architecture on the final surface quality. The simulations were shown to represent experimental data typically within 6%. [ABSTRACT FROM AUTHOR]

Analytical formulations for the pressure profile in rectilinear and radial flow vacuum infusion (VI) processes are developed. The coupled pressure formulations are solved using an iterative numerical procedure. As the formulations are coupled, reinforcement specific solutions need to be derived. The VI process is also modelled using a numerical flow simulation tool, using a previously reported approach. In addition, analytical formulations for fill times in the rectilinear and radial flow VI processes are developed. It is found that with increasing reinforcement compliance, the analytical VI pressure profile diverges from the resin transfer moulding (RTM) pressure profile. Results from numerical flow simulations show a similar behaviour. The error level in the numerical results of VI pressure solution depends on the reinforcement compliance. The fill times ratio, between equivalent RTM and VI processes, remains constant for rectilinear and radial flow processes. This allows one to use RTM flow simulation tools to model rectilinear and radial flow VI processes without any major modifications. [ABSTRACT FROM AUTHOR]

We investigated the role of the phosphatidylinositol-3 kinase (PI-3K) pathway in regulating the proliferation of primary chronic myeloid leukaemia (CML) progenitor cells by using imatinib to inhibit the activity of p210Bcr-Abl. The effect of imatinib on the expression of PI-3K pathway proteins was investigated by kinase assays and Western blotting; PI-3K was inhibited by wortmannin or LY294002, Jak2 by AG490 and farnesylation by FTI II; progenitor cell proliferation (self-renewal) was measured by growing myeloid colonies in vitro, then replating them to observe secondary colony formation. Suppression of p210Bcr-Abl with imatinib indirectly suppressed the activity of PI-3K and its downstream targets (Erk, Akt and p70S6 kinase), thereby implicating the PI-3K pathway in p210Bcr-Abl-mediated signalling in primary CML progenitor cells. The PI-3K inhibitors, wortmannin and LY294002 reproduced the differential effects of imatinib on normal and CML progenitor cell proliferation in vitro by increasing normal cell (P = 0.001) and reducing CML cell proliferation (P = 0.0003). This differential effect was attributable to dysregulated signalling by granulocyte colony-stimulating factor in CML. The responses of individual patient's cells to wortmannin correlated with their responses to imatinib (P = 0.004) but not their responses to AG490 (Jak2 kinase inhibitor) or FTI II (farnesyltransferase inhibitor). Individual responses to wortmannin also correlated with responses to interferon α (IFNα) (P = 0.016). Imatinib-resistant K562 cells were sensitive to LY294002. Inhibition of the PI-3K pathway may be common to imatinib and IFNα and reflect dysregulated cytokine signalling. As imatinib-resistant cells remained sensitive to wortmannin and LY294002, targeting the PI-3K pathway may provide an alternative therapy for imatinib-resistant patients. [ABSTRACT FROM AUTHOR]

The present paper examines the analysis and simulation of the vacuum assisted resin transfer molding process (VARTM). VARTM differs from the conventional resin transfer molding (RTM) in that the thickness of the preform varies during injection affecting permeability and fill time. First, a governing equation for VARTM is analytically developed from the fundamental continuity condition, and used to show the relation between parameters in VARTM. This analytical work is followed by the development of a numerical 1-D/2-D solution, based on the flow simulation software LIMS, which can be used to predict flow and time dependent thickness of the preform by introducing models for compaction and permeability. Finally, the results of a VARTM experimental plan, focusing on the study of the influence of outlet pressure on compaction and fill time, are correlated with both the analytical and the numerical work. The present work also proposes an explanation for the similarities between VARTM and RTM and shows when modeling VARTM and RTM can result in an oversimplification. [ABSTRACT FROM AUTHOR]

In recent years, the compression moulding of E-glass/polypropylene commingled composites has been thoroughly investigated. In particular, in the University of Nottingham, a number of studies have been carried out, trying to correlate moulding parameters with mechanical properties and microstructural void content. However, some aspects of commingled composites have received less coverage so far and are therefore dealt with in this paper. These concern the effect of the processing conditions of these materials on interlaminar shear strength and impact properties and the influence of the synergy between processing, microstructure and properties on the impact performance of commingled composite structures. With this aim, flat plaques of E-glass/polypropylene commingled composites with a different fibre architecture (twoand three-dimensional) were non-isothermally compression moulded under various moulding conditions and then tested. The test programme included falling weight impact tests with a staircase procedure, Charpy impact tests and interlaminar shear strength (ILSS) tests. To evaluate the consolidation of the laminates, void content measurement using optical microscopy was related to ILSS and impact test results. In particular, the specific issues arising in moulding laminates with added three-dimensional fibres were studied. These include correct placement of the tow, sufficient preheating of thick laminates and nesting of the layers during moulding. The results of these tests are discussed in the light of the moulding conditions and quality, and conclusions are drawn regarding optimum moulding conditions for impact performance. Finally, indications on the reliability and possible improvement of the moulding procedure to yield a sufficient moulding quality, even with large thickness, are also provided. The knowledge acquired on material consolidation properties is applied in the manufacture of an automotive side intrusion beam: problems due to the scale effect are also discussed. [ABSTRACT FROM AUTHOR]

The processing properties of fibrous preforms and the final properties of liquid moulded composite parts are strongly related to the internal architecture of the preforms. The architecture of a preform is determined by the individual textile layers from which it is made. In order to calculate the processing and final properties in the same way over all the volume of a preform or part made from different types of textile, some sets of equations that generate similar definitions of the textiles from their manufacturing parameters are required. The similarity of these definitions is assessed through a series of criteria stated in a previous paper by the present authors; definition modules for woven and braided textiles were also presented in that paper. This paper presents a definition module, or a set of equations, that generates similar definitions for non-crimp reinforcements assembled by warp knitting; the equations also apply for the stitched threads used to assemble multiple-layer preforms. The definitions obtained from this module obey the criteria mentioned previously. The sets of equations presented in both papers cover most technical textiles; similar sets of equations can be created for speciality reinforcements and applied to the calculation of diverse physical properties of the preforms and parts. As an example, this paper discusses the mapping of the voids which are defined between the tows and threads of non-crimp stitched reinforcements. [ABSTRACT FROM AUTHOR]

Predictive calculations of the physical properties of fibrous preforms and composite parts require an appropriate description of the preform geometry. Most internal dimensions of a preform are set during its manufacturing through mechanical interactions occurring between the tows and threads. However, the global shape and the interlacing patterns of the constituent textiles are determined independently. In this paper, a formal procedure for the description of the interlacing patterns is proposed. This procedure, which is based on the individual textile manufacturing processes, is general in the textiles considered and in the possible applications. The interlacing patterns are expressed by a series of vectors that follow a universal set of criteria and are generated from the values taken by the processing parameters. Defining examples are given for three-dimensional woven textiles and three-dimensional tubular braided textiles, and geometrical applications are also presented. Further examples for warp-knitted textiles and multiple-layer stacks will be given in a subsequent paper, together with examples of physical applications. [ABSTRACT FROM AUTHOR]

Hereditary haemochromatosis (HH) is an autosomal recessive disease linked to certain MHC class-I specificities. The disease is characterized by increased iron absorption and, in some patients, abnormally low numbers of CD8+ T cells in the periphery. We were interested in whether CD4- and CD8-associated p56lck kinase activities were altered in patients with HH. In a study of 18 patients with HH (with and without low numbers of CD8+ cells), the level of autophosphorylation of the CD8-associated p56lck as well as its phosphotransferase activity, as determined by phosphorylation of an exogenous substrate, was significantly reduced by two- to three-fold relative to a control population of 23 healthy blood donors (P < 6 x 10-7). CD8-p56lck activity was decreased in 16 out of 18 patients (ranging from 1.5- to 10-fold decrease). By contrast, the level of CD4-p56lck activity did not show an overall decrease relative to controls. In addition to an occasional decrease in the amount of CD8-associated lck, HH patient-derived T cells showed a consistent decrease in the relative CD8-p56lck specific activity. Immunofluorescence staining showed further that the difference could not be accounted by a discrepancy in the expression of CD8αα or CD8αβ complexes or MHC class I molecules. Decreased CD8-p56lck activity was seen both in patients undergoing intensive phlebotomy treatment and in patients in maintenance therapy (i.e. patients who had reached normal levels of iron stores), indicating that this abnormality does not appear to be corrected by iron depletion. To our knowledge, this is the first demonstration of an abnormality in a src-like receptor associated kinase in a human disease state linked to MHC class-I antigens. [ABSTRACT FROM AUTHOR]

The resin temperature distributions in a heated mould during the impregnation stage of resin transfer moulding have been investigated in this work. Effects such as the fibre content, the filling time and the mould and preform temperatures have been evaluated. It was shown that the fibre content and the filling time effects on the resin temperature distributions are less significant than the mould and preform temperatures. It was also shown that approximately 70% of the resin temperature increase is obtained within a flow path length of 12.5 cm. These trends led to the development of an empirical relation used to evaluate the influence on fill times of non-isothermal effects during filling. [ABSTRACT FROM PUBLISHER]