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In this study the effect of T6 heat treatment, two-step aging treatment and ultrasonic impact peening on the exfoliation corrosion behavior of welded EN AW 7020 was investigated. Exfoliation tests were performed according to the ASTM G34-01 standard. As expected, as a result of the tests, the base material region of all three samples were showed better corrosion resistance than the heat-affected region. Ultrasonic impact peening and two-step aging treatment was observed that improved EXCO sensitivity in the weld area. When sorting was made by considering the resistance to corrosion of the heat affected zone of the samples, it was observed that the best resistance was shown by the sample with two-step aging treatment, and the worst resistance was shown by the sample with T6 heat treatment.

The effect of two-step aging treatment on the fatigue behavior of welded AA 7020 Al. alloy was investigated. For fatigue tests to be carried out in atmospheric and seawater environments, a plane bending tester at a stress ratio of R= 0 was used. Experiments in the control group were carried out with unwelded specimens at a strain rate of R= −1 in air. The gradual heat treatment, two-step aging, significantly improved the fatigue and corrosion fatigue behavior of welded AA 7020 alloys. Unwelded specimens showed better fatigue properties than the welded ones. In the experiments in the seawater environment, pitting, and exfoliation corrosion occurred on the surfaces. It was determined that the corrosion pits reduce the fatigue life of welded and unwelded specimens. It was also observed that the corrosion sensitivity of the welded specimens increased in the heat affected zone and resulted in corrosion fatigue cracking.

Loa loa, also called the African eye worm, is a parasite that is found in Central and West Africa, especially along the Congo River. Infection with this parasite causes loiasis, which is characterized by swelling in the arms and legs, and the presence of the parasite in the blood (microfilaremia). In rare cases the parasite causes damage to the heart, eyes, kidneys and nerves. It is transmitted to man by the bite of an infected deer fly or mango fly. After a person has been bitten by an infected fly, it takes three years for the immature form of the parasite (larvae) to grow into an adult worm. The worms can remain in a person for as long as 17 years. Natives who live in regions of Africa where Loa loa is found have large numbers of the parasite in their blood, but do not have the characteristic symptom of swelling in their arms and legs. On the other hand, people who visit this region of Africa for long periods of time develop arm and leg swelling, but do not have detectable amounts of parasite in their blood. In an attempt to determine why this occurs, 51 West African natives with loiasis and 42 infected West African visitors were examined. Ninety percent of the natives had parasites in the blood, but only 16 percent had symptoms of swelling. Ten percent of the visitors had parasites in their blood while 95 percent had symptoms of swelling. The natives had lower levels of white blood cells, and lower levels of parasite-specific proteins known as antibodies. In addition, their white blood cells were less sensitive to the parasite. The authors conclude that the natives' immune systems (the body's natural defense system for fighting infection) react differently to the parasite, and this may explain why they have parasites in their blood but do not have symptoms of infection, while the opposite is true for the visitors. (Consumer Summary produced by Reliance Medical Information, Inc.)

Long-term stability of polymer electrolyte membrane fuel cells under dynamic operation still has a high potential for optimization, specifically for use in the automotive industry. This stability is especially affected by the degradation processes taking place in the cathode catalyst layer and hence should be fully understood. In this work, we develop a fast and reliable state-of-health model of the cathode catalyst layer, incorporating the electrochemical degradation processes related to anodic and cathodic platinum dissolution, oxidation, Pt loss due to ion diffusion, carbon corrosion and place exchange mechanisms as well as their interaction. For the purpose of validation, the model is developed alongside a comprehensive experimental data set. A detailed parameter study taking into account temperature, relative humidity and load profile dependency was carried out. A good agreement between model and experiment was found for load ranges between 0.6 and 0.95 V. Further, good approximation of the active surface area loss for cell temperatures between 60degC and 90degC and relative humidity between 30% and 100% were achieved.

This paper investigates the three-body wear resistance rates of five restorative dental composite materials at different mastication cycles and compares the results with that of an amalgam material. Five specimens of each material were exposed three-body wear tests using a computer-controlled chewing simulator with steatite balls as the antagonist (1.6 Hz, 49 N load; 120,000, 240,000 and 480,000 mechanical cycles; and thermal cycling between 5 and 55°C at 5 min/cycle and 3000 cycles) immersed in a poppy seed slurry (three-body wear environment). Initially, the microhardness values of the composite materials in the Vicker’s hardness (HV) scale were determined. The mean volume loss of the worn surfaces was measured with a three-dimensional profilometer. Means and standard deviations were calculated, and statistical analysis was performed using one-way ANOVA (α=0.05). Additionally, scanning electron microscopy analysis was performed to examine the wear tracks on the surface. The interactions between the composite resin and mean volume loss were found to be significant. The three-body wear rates for the composites Durafil and Kalore composite were significantly higher than those of the other composites and the amalgam irrespective of the number of mastication cycles. Filtek Z250 and Filtek Supreme composite resins had good three-body wear resistance similar to that of the amalgam. However, this study suggests that the correlation between Vicker’s hardness and three-body wear resistance is not significant.

La reparación del labio con tejido labial es el principio más fundamental al que debe tenderse cuando se quiere realizar una cirugía reparadora de esta región. Los labios responden a una doble exigencia, tanto esfinteriana como estética facial. Por consiguiente, se dispone de un arsenal muy amplio de procedimientos quirúrgicos que el cirujano plástico debe dominar, no sólo en cuanto a sus indicaciones, sino también en lo que respecta a su realización para intentar restituir de forma óptima la doble función del órgano labial. Estas indicaciones dependerán no sólo de la etiología de la pérdida de sustancia inicial, sino también de sus características y de las posibilidades de reconstrucción locales o a distancia. Por último, las entidades anatómicas que constituyen el aparato labial deben respetarse al máximo, como la unión cutaneomucosa, las comisuras o las subunidades estéticas para obtener el resultado más óptimo posible. La principal innovación en estos últimos años es la aparición de los colgajos de perforantes, en particular en «hélice», que permiten reconstrucciones a medida.

Catalyst degradation in membrane electrode assemblies was studied by voltage cycling in hydrogen/air atmosphere. The loss of electrochemically active surface area (ECSA) was quantified by cyclic voltammetry. The influence of cycle duration and dwell time during square wave voltage cycling on catalyst degradation was investigated, as well as the effect of scan rate on ECSA loss during triangular wave voltage cycling. Degradation rates per voltage cycle increased with longer cycle duration and lower scan rate, while degradation rates normalized to operating time were approximately constant over a wide range of cycle lengths and scan rates. The results suggest that the formation of a (sub-)surface oxide layer and cathodic dissolution are important processes in the platinum dissolution mechanism.

The author discusses the behavior, experiences and ideas of youth today. According to the author, many perceptions of youth are rooted in fear and that this fear has at times led to policy and program decisions that overextend the experience with some youth. The culture of fear can only be changed through reaching out, engaging listening, understanding and setting aside premature judgement.

The purpose of this review is to highlight some recent advances in our understanding of chewing simulation tests and wear mechanisms and how they contribute to material failures in the complex oral environment. Within in this study scope, as intraoral wear parameters; chewing force, tooth sliding distance, thermal change, food abrasiveness, saliva lubrication, and behavior of antagonist materials were investigated. In addition to the characteristics of chewing simulators that can simulate the intraoral tribological process in a laboratory environment have been investigated. It is a complex process to simulate the environment that a biomaterial placed in the human body is exposed to in a laboratory environment. Therefore, it is of great importance that the parameters applied in the wear test mechanisms carried out in the laboratory environment can simulate the behavior of living tissue. Additionally, both fatigue and abrasion loads of composite restorations can be important in achieving poor mechanical behavior, which is the leading cause of composite restoration failures. Overall, understanding the connectivity of all two procedures, while developing a mechanical definition of fatigue, wear mechanisms, are seen as key keys to successfully using in vitro studies to predict in vivo results and develop improved dental restorative materials.

L’amplification du gène codant pour FGFR1 par des lignées tumorales pulmonaires a été corrélée à une meilleure sensibilité aux inhibiteurs tyrosine kinase anti-FGFRs (1). Cette amplification est retrouvée dans 17 % des carcinomes épidermoïdes des voies aérodigestives supérieures (VADS) (2), ce qui incite à déterminer si cette amplification nous permettrait de sélectionner les patients susceptibles de répondre à une potentielle thérapie ciblant les FGFRs.