Coupled Effect of High Temperature and Heating Time on the Residual Strength of Normal and High-Strength Concretes

This paper is part of a present research that leads to estimate the level of concrete degradation properties altered by high temperatures, especially by using the maturity concept. In order to evaluate the coupled effect of high temperature and heating time on the residual strength of concrete, a series of compressive and indirect tensile tests was performed on normal and high strength concretes. The effect of incorporating polypropylene fibers in high strength concretes was also investigated. Cubical concrete specimens were exposed to different target high temperatures (100, 300, 500 and 700 ºC) for 3, 6 and 9 hours and then cooled in air. Compressive and flexural strengths of these concrete samples were compared with each other and with the unheated samples. Experimental results indicate that concrete strength decreases with increasing temperature and heating time. The grade of concrete affects the residual compressive and flexural strength; the decrease in the strength of ordinary concrete is more than that in High Performance Concrete (HPC), the effect being more pronounced as the heating time increases. Polypropylene fibers were found to have a beneficial effect on residual strength of HPC at least at high temperatures over their melting and vaporization

Modeling the Influence of Limestone Filler on Concrete: A Novel Approach for Strength and Cost

The use of limestone fillers as additions in concrete has grown because they present several advantages over ordinary cements. Production of composite cements has caused a necessary shift in the manufacture process used in the cement industry. Now, it is known that the separate grinding and mixing technology is more convenient in order to produce these cements, called market-oriented or tailor-made cements. However, their optimum formulations require the help of methods of experimental design. In this study, the incorporation of limestone fines and their optimal is analyzed in concrete, where Portland cement was replaced by up to 42 %. The fillers were chosen to be of various particle sizes. The resulting concretes are compared for compressive strength, cement consumption and economic viability. The results obtained indicate the advantage of incorporation of limestone fines in the concretes, as for the same compressive strength at 28 days, savings up to 23% in the consumption of cement were achieved, which represents a significant reduction of energy, raw material consumption and costs. The XRD analyses of samples cured up to 28 days showed that this amelioration is due to formation of new hydrated compounds. It is concluded that an addition of finely ground limestone filler up to 18% gives a better strength for the same cement content and reduces the cost of concrete for the same target strength

Review of bio-particle manipulation using dielectrophoresis

During the last decade, large and costly instruments are being replaced by system based on microfluidic devices. Microfluidic devices hold the promise of combining a small analytical laboratory onto a chip-sized substrate to identify, immobilize, separate, and purify cells, bio-molecules, toxins, and other chemical and biological materials. Compared to conventional instruments, microfluidic devices would perform these tasks faster with higher sensitivity and efficiency, and greater affordability. Dielectrophoresis is one of the enabling technologies for these devices. It exploits the differences in particle dielectric properties to allow manipulation and characterization of particles suspended in a fluidic medium. Particles can be trapped or moved between regions of high or low electric fields due to the polarization effects in non-uniform electric fields. By varying the applied electric field frequency, the magnitude and direction of the dielectrophoretic force on the particle can be controlled. Dielectrophoresis has been successfully demonstrated in the separation, transportation, trapping, and sorting of various biological particles.Singapore-MIT Alliance (SMA

A shortening of the life-cycle of major tropical cyclones

In this study a comprehensive picture of the changing intensity life cycle of major (Category 3 and higher) tropical cyclones (TCs) is presented. Over the past decades, the lifetime maximum intensity has increased, but there has also been a significant decrease in duration of time spent at intensities greater than Category 1. These compensating effects have maintained a stable global mean‐accumulated cyclone energy of individual major TCs. The global mean duration of major TCs has shortened by about 1 day from 1982 to 2018. There has been both faster intensification (Categories 1 to 3) and weakening (Categories 3 to 1) by about 40%. The probabilities of rapid intensification and rapid weakening have both risen in the period 2000–2018 compared to 1982–1999. A statistically significant anticorrelation is found between the lifetime maximum intensity and the following duration of the final weakening. This suggests an element of self‐regulation of TC life cycles

A theory for bone resorption based on the local rupture of osteocytes cells connections: A finite element study

In this work, a bone damage resorption finite element model based on the disruption of the inhibitory signal transmitted between osteocytes cells in bone due to damage accumulation is developed and discussed. A strain-based stimulus function coupled to a damage-dependent spatialfunction is proposed to represent the connection between two osteocytes embedded in the bone tissue. The signal is transmitted to the bone surface to activate bone resorption. The proposed modelis based on the idea that the osteocyte signal reduction is not related to the reduction of the stimulus sensed locally by osteocytes due to damage, but to the difficulties for the signal in travelling along a disrupted area due to microcracks that can destroy connections of the intercellular network between osteocytes and bone-lining cells. To check the potential of the proposed model to predict the damage resorption process, two bone resorption mechano-regulation rules corresponding to twomechanotransduction approaches have been implemented and tested: 1) Bone resorption based on a coupled strain-damage stimulus function without ruptured osteocyte connections (NROC); and 2) Bone resorption based on a strain stimulus function with ruptured osteocyte connections (ROC). The comparison between the results obtained by both models, shows that the proposed model based on ruptured osteocytes connections predicts realistic results in conformity with previously published findings concerning the fatigue damage repair in bone

Cultural Variations in Public Beliefs about Mental Disorders: A Comparison between Tunisia and Germany

In recent years there is a growing interest in public beliefs about mental disorders. Numerous representative population-based studies have been conducted around the globe, also in European countries bordering on the Mediterranean Sea. However, relatively little is known about public beliefs in countries in Northern Africa. To fill this gap by comparing public beliefs about mental disorders in Tunisia and Germany, focusing on causal beliefs, help-seeking recommendations and treatment preferences. Representative national population-based surveys have been conducted in Tunisia in 2012 (N = 811) and in Germany in 2011 (N = 1852), using the same interview mode and the same fully structured interview starting with a vignette depicting a person suffering from either schizophrenia or depression. In Tunisia, the public was more likely to adopt psychosocial and to reject biogenetic explanations than in Germany. Correspondingly, psychological treatments were more frequently recommended and biological ones more frequently advised against. There was also a strong inclination to share religious beliefs and to recommend seeking religious advice. Tunisians tended much more than Germans to hold moralistic views and to blame the afflicted person for his or her illness. In Tunisia, the public tended less to differentiate between schizophrenia and depression than in Germany. Marked differences between Tunisia and Germany exist in public beliefs about the causes of mental disorders and their treatment, which correspond to differences in cultural orientations prevailing in these countries. Mental health professionals need to be sensitive to the particular cultural context in which they operate, in order to be able to reach those they intend to care for

Mucormycose rhinosinusienne a extension palatine

Les mucormycoses sont des infections fongiques, aigues, rares et souvent fatales. Elles touchent avec prédilection les sujets  immunodéprimés. La forme rhinocérébrale est la plus fréquente. Le diagnostic repose sur l’examen clinique, anatomopathologique et mycologique. L’approche thérapeutique doit être multidisciplinaire. Les auteurs rapportent l’histoire clinique d’un patient, ayant présenté une mucormycose rhinosinusienne avec atteinte du palais au décours d’une infection dentaire. A travers cette observation, ils discutent les différents aspects cliniques, les moyens du diagnostic et les modalités thérapeutiques de la mucormycose rhinocérébrale.Mots clés : Infection fongique, mucormycose rhinocérébrale, zygomycètes, pronostic, traitement