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The cure degree must be as uniform as possible during the manufacture of polymer matrix composite components in order to have a product without defects. For thick composite components, this condition is not often respected, in fact, the cure degree trend between the core and the external surface is different causing structural and geometrical/dimensional unconformities. In most cases, these problems can be solved through a redesign of cure process in terms of thermal cycle, in fact that one recommended by furnisher is usually suitable for thin components. The optimization of cure thermal cycle should include several performance criteria for the production system such as the targeted cure degree, the targeted maximum temperature of the part and the duration of the cure cycle, as well as the production system limitations such as the maximum allowable heating rate, the maximum allowable cooling rate and so on. A previous work shows a method to optimize the cure degree of a thick composite component. The present work presents an indirect way to validate the proposed method: some experimental tests have been carried out by implementing the cure cycle identified by this method, the values of temperatures have been recorded by thermocouples and the obtained temperature trend has been compared with that due to numerical approach. Further considerations on the cure degree and the cure rate have been deduced. The experimental results show a good agreement with the numerical ones. [ABSTRACT FROM AUTHOR]

In liquid resin infusion processes, the compression phase and the resin flow are important stages that influence the quality of the obtained parts. In this study, an experimental device is presented to measure thickness and pressure variations in order to obtain an experimental compressibility curve that can be implemented in a software dedicated to numerical simulations. To perform these experiments no typical compression testing machine is required and there is no test fluid. The aim of this work is to present a new methodology in order to obtain an empirical relation to determine the compressibility as a power law function. In order to evaluate the reliability of the proposed methodology, the obtained experimental curve is compared with another curve achieved performing standard compaction test. [ABSTRACT FROM AUTHOR]

Through mechanobiological control of the extracellular matrix, and hence local stiffness, smooth muscle cells of the media and fibroblasts of the adventitia play important roles in arterial homeostasis, including adaptations to altered hemodynamics, injury, and disease. We present a new approach to model arterial wall mechanics that seeks to define better the mechanical environments of the media and adventitia while avoiding the common prescription of a traction-free reference configuration. Specifically, we employ the concept of constituent-specific deposition stretches from the growth and remodeling literature and define a homeostatic state at physiologic pressure and axial stretch that serves as a convenient biologically and clinically relevant reference configuration. Information from histology and multiphoton imaging is then used to prescribe structurally motivated constitutive relations for a bi-layered model of the wall. The utility of this approach is demonstrated by describing in vitro measured biaxial pressure-diameter and axial force-length responses of murine carotid arteries and predicting the associated intact and radially cut traction-free configurations. The latter provides a unique validation while confirming that this constrained mixture approach naturally recovers estimates of residual stresses, which are fundamental to wall mechanics, without the usual need to prescribe an opening angle that is only defined conveniently on cylindrical geometries and cannot be measured in vivo. Among other findings, the model suggests that medial and adventitial stresses can be nearly uniform at physiologic loads, albeit at separate levels, and that the adventitia bears increasingly more load at supra-physiologic pressures while protecting the media from excessive stresses. [ABSTRACT FROM AUTHOR]

Objectives: To establish the efficacy of low-level laser therapy for tinnitus. Methods: We performed a prospective, randomized double-blind study on 60 outpatients with tinnitus presenting sensorineural hearing loss in the affected ear. They were randomly divided into two groups, the first performing active laser therapy 20 min a day for 3 months with a 650-nm, 5-mW soft laser (group L), the second using a dummy device which duplicated all aspects of active laser therapy except for the activation of the laser beam (group C). One subject in both groups dropped out due to an increase in tinnitus loudness. Two more patients in each group ceased to comply with the protocol due to familiar problems. Results: The Tinnitus Handicap Inventory (THI) was considered the main outcome measure; no statistical difference was detected between the 2 groups in the THI total score (p = 0.97), and its functional (p = 0.89), emotional (p = 0.89) and catastrophic (p = 0.89) subscales. Moreover, a visual analog scale for self-perceived loudness of the tinnitus showed no difference between the groups (p = 0.69). Regarding psychoacoustic parameters, the minimum masking level showed no difference (p = 0.42), while loudness expressed in sensation level exhibited lower values in group L (p = 0.0127). Group L subjects also presented a decreased rate of hyperacusis (p = 0.02). No changes were detected in the audiometric threshold in both groups. Conclusions: Soft laser therapy demonstrated no efficacy as a therapeutic measure for tinnitus. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

• A structural-mechanical model is proposed to describe the cyclic behaviour of SMA. • A microstructural model is used to evaluate the level of phase transformation. • Model parameters depend on loading conditions and number of cycles. • Alloy stiffness in the plateau depends on those of the constituent phases. Shape memory alloys are able to recover the initial shape even after a large deformation. The memory property is due to the ability to change the microstructure under a variation of the stress state or the temperature. The stress–strain curve is characterized by the presence of a stage where the slope of the curve sharply decreases and the initial microstructure transforms into a new one. In this work, an integrated microstructural-mechanical model is proposed for the equiatomic NiTi shape memory alloy, that is suitable to predict the cyclic behaviour of a pseudoelastic shape memory alloy starting from the microstructure composition. [ABSTRACT FROM AUTHOR]

A voxel-based reconstruction algorithm, targeted at the generation of finite element (FE) meshes of structures with schematic geometry, is presented. The algorithm is able to generate three dimensional fully hexahedral FE meshes of structures composed of volumes with a schematic geometry. In order to be meshed, each volume must be described in terms of a set of surfaces which enclose the volume. Due to its schematic nature, the method allows the generation of fully parameterized FE models, thus it facilitates the investigation of the mechanical relevance of geometrical parameters by speeding up the mesh generation process. The algorithm was employed in the automatic construction of an FE model of the C3-C7 spinal segment with schematic geometry, made up exclusively of hexahedral elements. Non-linear simulations were carried out in different loading conditions: flexion- extension, lateral bending and axial rotation. The results were compared to data retrieved from the literature in order to ensure the validity of the model. Moment-rotation curves for each loading condition were determined. The range of motion was obtained for each spinal unit and loading condition. Both principal and coupled rotations were determined in lateral bending and axial rotation, for each spinal unit. The intradiscal pressure was also computed in the nucleus pulposus, for all the intervertebral levels. Geometrical parameterization of the models offers potential for the biomechanical investigation of pathologic conditions and surgical procedures, such as spinal fusion and disc arthroplasty, even on a patient-specific basis. [ABSTRACT FROM AUTHOR]

Objectives The risk of uniparental disomy (UPD) occurrence associated with the prenatal finding of balanced nonhomologous Robertsonian translocations (NHRTs) has been estimated only on limited empirical data. The aim of the study was to verify the estimate of the general risk, to get narrower confidence intervals by cumulating the data and to obtain risk estimates for specific translocation types. Methods We tested for UPD 160 prenatal specimens referred to the participant centers after the cytogenetic finding of NHRT. Results One case of upd(14)mat was found, associated with a 45,XX,der(14;22)mat fetal karyotype. The general empirical risk of UPD occurrence in NHRT carrier fetuses, corrected for the actual number of chromosomes analyzed, was 0.76% (95% CI 0.02-4.25%). Cumulative data with previous studies gives a general risk of UPD associated with NHRT of 0.80% (95% CI 0.17-2.34%). The UPD risk for the specific NHRT der(13;14) did not significantly differ from that of the other NHRTs taken together. Conclusion The present survey confirms the previously estimated risk of occurrence of UPD in offspring of NHRT carriers as a low, but not negligible risk, worth being investigated in prenatal diagnosis. Copyright © 2004 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The lead(II) chloride [{N^NiPr}PbCl] (1), where {N^N}− is a bulky, monoanionic, bidentate iminoanilide ligand, was synthesised by salt metathesis between [{N^NiPr}Li] and PbCl2. The complex was characterised by X-ray diffraction crystallography and 207Pb nuclear magnetic resonance (NMR) spectroscopy. It exists in the molecular solid state as a monometallic three-coordinate species, with two independent, similar but not identical molecules per asymmetric unit. The differences between the first coordination sphere of 1 and that of Fulton’s structurally related β-diketiminato complex [{N^NiPr}PbCl] are illustrated. The synthesis of 1 offers a convenient handle in the still underdeveloped organometallic and inorganic chemistry of lead(II), as exemplified by the synthesis of the alkyl complex [{N^NiPr}PbCH(CH3)2] (3). The iodo complex [{N^NiPr}PbI] (2) was also synthesised, but, unlike 1, it showed limited stability in solution.

Marine protected areas (MPAs) are among the most widely used strategy to protect marine ecosystems and are typically designed to protect specific habitats rather than a single and/or multiple species. To inform the conservation of species of conservation concern there is the need to assess whether existing and proposed MPA designs provide protection to these species. For this, information on species spatial distribution and exposure to threats is necessary. However, this information if often lacking, particularly for mobile migratory species, such as marine turtles. To highlight the importance of this information when designing MPAs and for assessments of their effectiveness, we identified high use areas of post-nesting hawksbill turtles (Eretmochelys imbricata) in Brazil as a case study and assessed the effectiveness of Brazilian MPAs to protect important habitat for this group based on exposure to threats. Most (88%) of high use areas were found to be exposed to threats (78% to artisanal fishery and 76.7% to marine traffic), where 88.1% were not protected by MPAs, for which 86% are exposed to threats. This mismatch is driven by a lack of explicit conservation goals and targets for turtles in MPA management plans, limited spatial information on species' distribution and threats, and a mismatch in the scale of conservation initiatives. To inform future assessments and design of MPAs for species of conservation concern we suggest that managers: clearly state and make their goals and targets tangible, consider ecological scales instead of political boundaries, and use adaptative management as new information become available. [ABSTRACT FROM AUTHOR]