Mode III interlaminar fracture of carbon/epoxy laminates using the edge crack torsion (ECT) test

The mode III interlaminar fracture of carbon/epoxy laminates was evaluated with the edge crack torsion (ECT) test. Three-dimensional finite element analyses were performed in order to select two specimen geometries and an experimental data reduction scheme. Test results showed considerable non-linearity before the maximum load point and a significant R-curve effect. These features prevented an accurate definition of the initiation point. Nevertheless, analyses of non-linearity zones showed two likely initiation points corresponding to GIIIc values between 850 and 1100 J/m2 for both specimen geometries. Although any of these values is realistic, the range is too broad, thus showing the limitations of the ECT test and the need for further research.

Adherend thickness effect on the tensile fracture toughness of a structural adhesive using an optical data acquisition method

Adhesive bonding is nowadays a serious candidate to replace methods such as fastening or riveting, because of attractive mechanical properties. As a result, adhesives are being increasingly used in industries such as the automotive, aerospace and construction. Thus, it is highly important to predict the strength of bonded joints to assess the feasibility of joining during the fabrication process of components (e.g. due to complex geometries) or for repairing purposes. This work studies the tensile behaviour of adhesive joints between aluminium adherends considering different values of adherend thickness (h) and the double-cantilever beam (DCB) test. The experimental work consists of the definition of the tensile fracture toughness (GIC) for the different joint configurations. A conventional fracture characterization method was used, together with a J-integral approach, that take into account the plasticity effects occurring in the adhesive layer. An optical measurement method is used for the evaluation of crack tip opening and adherends rotation at the crack tip during the test, supported by a Matlab® sub-routine for the automated extraction of these quantities. As output of this work, a comparative evaluation between bonded systems with different values of adherend thickness is carried out and complete fracture data is provided in tension for the subsequent strength prediction of joints with identical conditions.

Orbital forcing of stratal patterns in an inner platform carbonate sucession: an example from an Upper Hauterivian series of the Lusitanian Basin, Portugal

With an example taken from a late-Hauterivian series of the Lusitanian Basin (Portugal), we will demonstrate the sedimentary record of orbital pattern variations and, consequently, climate variations in an inner platform environment with patterns and isolation changes, allows us to establish 4 major orders of periodicity related to orbital components:- The large cycles ob bed thickness variation, constituted by 31-32 beds, recording the 400 ky eccentricity cycle component;- The medium cycles, represented by byndles of 8-9 beds, related to the 100 ky eccentricity cycle component; - The small cycles, of 3-5 beds, recording the 41 ky obliquity components;- The very small cycles, of 2 beds, related to the 22 ky and 26 ky precession components. The mean duration of each bed is around 11.8 ky, a number very close to that of the precession hemi-cycle. Climatic control on qualitative production is confirmed by the close relation between the bed thickness variations, the insolation variability and the variation of micritized elements concentrations.

Orbital tuberculosis diagnosed by immunohistochemistry: case reports

PURPOSE: To describe three cases of orbital tuberculosis, with their clinical characteristics and respective diagnostic procedures, showing the importance of histopathology for the correct diagnosis. PATIENTS AND METHODS: Three patients diagnosed and treated for orbital tuberculosis, in the "Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo" during the years of 1999 and 2001. RESULTS: All of the patients were female and referred a chronic evolution of swelling of one eyelid associated or not with other symptoms. They had not HIV infection. Two of them had positive epidemiology for tuberculosis. However, the search for systemic evidence of the disease and staining for bacilli (Ziehl-Neelsen method) were negative in all three patients. In all the cases, only the biopsy with immunohistochemical analysis could confirm the diagnosis. COMMENTS: Orbital involvement is a rare ocular manifestation of tuberculosis. Even in a tertiary hospital, few cases, if any, are diagnosed per year. However, the global incidence and prevalence of M. tuberculosis infections is not under control yet, and it has been a serious public health problem. Thus, one must be aware of the possibility of tuberculosis among the orbital diseases.

Orbital Exenteration for Eyelid Skin Carcinoma

Exenteration of the orbit is a disfiguring and destructive procedure; it is generally performed for orbital malignancies and often provides a significant reconstructive challenge. Our purpose was to evaluate the clinical indications for orbital exenteration in a tertiary referral center and to assess the reconstructive options employed. A retrospective nonrandomized analysis was performed, selecting all patients undergoing orbital exenteration over a 5-year period, between January 2005 and January 2010. Patient demographics, tumor characteristics, and reconstructive techniques used were evaluated. Twenty patients with a mean age of 76.5 years underwent total orbital exenteration. Basal cell carcinoma was the main operative indication (45%), followed by squamous cell carcinoma (15%). Reconstructive techniques included cover of the raw orbital cavity with a temporal muscular flap in all cases followed with split skin grafting (25%), bilaterally pedicle V-Y advancement flap (10%) and a fasciocutaneous island flap of the retroauricular region (65%). Twenty percent of patients had local complications and all were treated in a satisfactory fashion. Eyelid skin tumors remain an important cause of orbital exenteration. Temporal muscle flap is a reliable and stable reconstructive solution after orbital exenteration and additional aid is supplied with skin grafts or local flaps. This technique ensures a good aesthetic outcome and better situation for later complementary treatments and minimal associated donor site morbidity.

Tensile fracture characterization of adhesive joints by standard and optical techniques

The use of adhesive joints has increased in recent decades due to its competitive features compared with traditional methods. This work aims to estimate the tensile critical strain energy release rate (GIC) of adhesive joints by the Double-Cantilever Beam (DCB) test. The J-integral is used since it enables obtaining the tensile Cohesive Zone Model (CZM) law. An optical measuring method was developed for assessing the crack tip opening (δn) and adherends rotation (θo). The proposed CZM laws were best approximated by a triangular shape for the brittle adhesive and a trapezoidal shape for the two ductile adhesives.

Undrestanding postoperative cognitive dysfunction: novel insights

ABSTRACT: Background: Sleep is integral to biological function and sleep disruption can result in both physiological and psychological dysfunction. The acute cognitive consequences of sleep loss has been an active field of recent investigation, evidence suggests that sleep disruption in critically ill older adults can result in acute decrements in cognitive functioning. Surgery activates the innate immune system, inducing neuroinflammatory changes that interfere with cognition. The fact that patients with sleep disorders have an increased likelihood of exhibiting postoperative delirium encourages us to investigate the contribution of perioperative SF to the neuroinflammatory and cognitive responses of surgery. Methods: The effects of 24h sleep fragmentation (SF) and surgery were explored on adult C57BL/6J male mice. SF procedure started at 7 am with the home-cages being placed on a large platform orbital shaker cycled every 120 seconds (30 sec on/90 sec off). This procedure lasted for 24h. Stabilized tibia fracture was performed either before or after the 24h SF procedure. Separate cohorts of mice were tested for systemic and hippocampal inflammation and cognition. Results: Twenty-four hours of SF induced non-hippocampal memory dysfunction and increase in systemic IL-6. SF and surgery caused hippocampal-dependent memory impairment, although memory impairment was not exacerbated by combining SF with surgery. One day after either SF or surgery there was a significant increase in IL6 mRNA and TNF-alpha mRNA. These increments were more pronounced when either pre or post operative SF was combined with surgery. Conclusions: We show that while SF and surgery can independently produce significant memory impairment, perioperative SF significantly increased hippocampal inflammation without further cognitive impairment. The dissociation between neuroinflammation and cognitive decline may relate to our use of a sole memory paradigm that does not capture other aspects of cognition, especially learning.

Surgical treatment of endocrine exophthalmos by removal of orbital fat: clinical experience

PURPOSE: To report a series of 73 patients with endocrine exophthalmos treated by removal of orbital fat using the transpalpebral approach during the period 1989 to 1999. METHODS: The operation was performed according to the technique described by Olivari. Aesthetic analysis was done preoperatively and postoperatively (more than 6 months after surgery). The number of complications was also observed. RESULTS: The average volume of resected fat was approximately 7.6 mL per orbit. No major complication was observed. In 9 patients with epiphora, all improved. One patient developed postoperative diplopia and 5 complained of temporary diplopia. Appearance improved in 62 patients (85%). CONCLUSION: Surgical removal of orbital fat associated with endocrine exophthalmos provides consistent improvement in appearance with a low rate of complications. Additional procedures may be indicated to improve the cosmetic outcome.

Bone turnover markers for early detection of fracture healing disturbances: A review of the scientific literature

Imaging techniques are the standard method for assessment of fracture healing processes. However, these methods are perhaps not entirely reliable for early detection of complications, the most frequent of these being delayed union and non-union. A prompt diagnosis of such disorders could prevent prolonged patient distress and disability. Efforts should be directed towards the development of new technologies for improving accuracy in diagnosing complications following bone fractures. The variation in the levels of bone turnover markers (BTMs) have been assessed with regard to there ability to predict impaired fracture healing at an early stage, nevertheless the conclusions of some studies are not consensual. In this article the authors have revised the potential of BTMs as early predictors of prognosis in adult patients presenting traumatic bone fractures but who did not suffer from osteopenia or postmenopausal osteoporosis. The available information from the different studies performed in this field was systematized in order to highlight the most promising BTMs for the assessment of fracture healing outcome.

Análise derivativa de dados hiperespectrais medidos em nível de campo e orbital para caracterizar a composição de águas opticamente complexas na Amazônia

A técnica de análise derivativa de dados espectrais foi usada para estudar a variação dos constituintes opticamente ativos (COAs) na água, por meio de dados de campo e de imagens do sensor orbital Hyperion/EO-1. A imagem Hyperion usada neste estudo foi adquirida no dia 23 de junho de 2005, no final do período de cheia. Uma campanha de campo foi realizada entre 23 e 29 de junho de 2005, para coletar dados espectrais e limnológicos in situ. A imagem foi pré-processada visando eliminar faixas de pixels anômalos e convertida de valores de radiância para reflectância de superfície, portanto, corrigidos dos efeitos de absorção e espalhamento atmosféricos. Uma análise da correlação foi realizada para examinar a associação da reflectância e de sua primeira derivada espectral com as concentrações dos COAs. Melhores resultados foram obtidos após a diferenciação dos espectros, o que ajudou a reduzir a influência de efeitos indesejáveis, provindos de diferentes fontes de radiância, sobre as medidas de reflectância da superfície da água realizadas em ambos os níveis de aquisição de dados. Por meio de ajustes de regressões empíricas, considerando o conjunto de dados Hyperion, a primeira derivada espectral em 711 nm explicou 86% da variação da concentração de sedimentos inorgânicos em suspensão (µg.l-1) e a primeira derivada espectral em 691 nm explicou 73% da variação na concentração da clorofila-alfa (µg.l-1). As relações de regressão foram não-lineares, pois, em geral, as águas que se misturam na planície de inundação Amazônica se tornam opticamente complexas. A técnica de análise derivativa hiperespectral demonstrou potenciais para mapear a composição dessas águas.

Influence of casting condition on the anisotropy of the fracture properties of Steel Fibre Reinforced Self-Compacting Concrete (SFRSCC)

Identification of the tensile constitutive behaviour of Fibre Reinforced Concrete (FRC) represents an important aspect of the design of structural elements using this material. Although an important step has been made with the introduction of guidance for the design with regular FRC in the recently published fib Model Code 2010, a better understanding of the behaviour of this material is still necessary, mainly for that with self-compacting properties. This work presents an experimental investigation employing Steel Fibre Self-Compacting Concrete (SFRSCC) to cast thin structural elements. A new test method is proposed for assessing the post-cracking behaviour and the results obtained with the proposed test method are compared with the ones resulted from the standard three-point bending tests (3PBT). Specimens extracted from a sandwich panel consisting of SFRSCC layers are also tested. The mechanical properties of SFRSCC are correlated to the fibre distribution by analysing the results obtained with the different tests. Finally, the stress-crack width constitutive law proposed by the fib Model Code 2010 is analysed in light of the experimental results.

Parametric analysis of different compact tension specimens for fracture toughness characterisation in woven composite materials

Estudi elaborat a partir d’una estada a l’ Imperial College London, entre juliol i novembre de 2006. En aquest treball s’ha investigat la geometria més apropiada per a la caracterització de la tenacitat a fractura intralaminar de materials compòsits laminats amb teixit. L’objectiu és assegurar la propagació de l’esquerda sense que la proveta falli abans per cap altre mecanisme de dany per tal de permetre la caracterització experimental de la tenacitat a fractura intralaminar de materials compòsits laminats amb teixit. Amb aquesta fi, s’ha dut a terme l’anàlisi paramètrica de diferents tipus de provetes mitjançant el mètode dels elements finits (FE) combinat amb la virtual crack closure technique (VCCT). Les geometries de les provetes analitzades corresponen a la proveta de l’assaig compact tension (CT) i diferents variacions com la extended compact tension (ECT), la proveta widened compact tension (WCT), tapered compact tension (TCT) i doubly-tapered compact tension (2TCT). Com a resultat d’aquestes anàlisis s’han derivat diferents conclusions per obtenir la geometria de proveta més apropiada per a la caracterització de la tenacitat a fractura intralaminar de materials compòsits laminats amb teixit. A més, també s’han dut a terme una sèrie d’assaigs experimentals per tal de validar els resultats de les anàlisis paramètriques. La concordança trobada entre els resultats numèrics i experimentals és bona tot i la presència d’efectes no previstos durant els assaigs experimentals.

Minimal invasive surgery for coronoid fracture: technical note.

Operative treatment of coronoid fracture often requires a large dissection of soft tissue, resulting in elbow stiffness and functional limitation. The authors present a minimal invasive, safe technique, useful in the case of isolated coronoid fracture associated with elbow dislocation. This technique does not require soft tissue dissection and allows an early unlimited resumption of sports activities.

Which screening strategy using BMD measurements would be most cost effective for hip fracture prevention in elderly women? A decision analysis based on a Markov model.

INTRODUCTION: Hip fractures are responsible for excessive mortality, decreasing the 5-year survival rate by about 20%. From an economic perspective, they represent a major source of expense, with direct costs in hospitalization, rehabilitation, and institutionalization. The incidence rate sharply increases after the age of 70, but it can be reduced in women aged 70-80 years by therapeutic interventions. Recent analyses suggest that the most efficient strategy is to implement such interventions in women at the age of 70 years. As several guidelines recommend bone mineral density (BMD) screening of postmenopausal women with clinical risk factors, our objective was to assess the cost-effectiveness of two screening strategies applied to elderly women aged 70 years and older. METHODS: A cost-effectiveness analysis was performed using decision-tree analysis and a Markov model. Two alternative strategies, one measuring BMD of all women, and one measuring BMD only of those having at least one risk factor, were compared with the reference strategy "no screening". Cost-effectiveness ratios were measured as cost per year gained without hip fracture. Most probabilities were based on data observed in EPIDOS, SEMOF and OFELY cohorts. RESULTS: In this model, which is mostly based on observed data, the strategy "screen all" was more cost effective than "screen women at risk." For one woman screened at the age of 70 and followed for 10 years, the incremental (additional) cost-effectiveness ratio of these two strategies compared with the reference was 4,235 euros and 8,290 euros, respectively. CONCLUSION: The results of this model, under the assumptions described in the paper, suggest that in women aged 70-80 years, screening all women with dual-energy X-ray absorptiometry (DXA) would be more effective than no screening or screening only women with at least one risk factor. Cost-effectiveness studies based on decision-analysis trees maybe useful tools for helping decision makers, and further models based on different assumptions should be performed to improve the level of evidence on cost-effectiveness ratios of the usual screening strategies for osteoporosis.