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La reparacion del labio con tejido labial es el principio mas fundamental al que debe tenderse cuando se quiere realizar una cirugia reparadora de esta region. Los labios responden a una doble exigencia, tanto esfinteriana como estetica facial. Por consiguiente, se dispone de un arsenal muy amplio de procedimientos quirurgicos que el cirujano plastico debe dominar, no solo en cuanto a sus indicaciones, sino tambien en lo que respecta a su realizacion para intentar restituir de forma optima la doble funcion del organo labial. Estas indicaciones dependeran no solo de la etiologia de la perdida de sustancia inicial, sino tambien de sus caracteristicas y de las posibilidades de reconstruccion locales o a distancia. Por ultimo, las entidades anatomicas que constituyen el aparato labial deben respetarse al maximo, como la union cutaneomucosa, las comisuras o las subunidades esteticas para obtener el resultado mas optimo posible. La principal innovacion en estos ultimos anos es la aparicion de los colgajos de perforantes, en particular en «helice», que permiten reconstrucciones a medida.

Aim: The purpose of this study was to evaluate the Vicker's hardness and surface roughness of eight different composite materials immersed artificial saliva and distill water. Materials and Methods: Five standardized disc shape specimens (2mm diameter X 2mm height) were prepared from eight composite materials (Grandio, Estelite Flow, Filtek Bulk-fill, Charisma, Clearfil, Ultimate, Quadrant and G-aenial for each artificial aging environment. Specimens were immersed during 7, 90 and 180 days in artificial saliva and distill water at 37 °C respectively. The Vicker's hardness and surface roughness values of the samples were measured after each artificial aging period. Mean values and standard deviations were calculated and statistical analysis was performed using one-way ANOVA. Results: In this study Vicker's hardness and surface roughness values of all samples significantly increased after both in artificial saliva and distill environment 7 days aging period. Conclusion: In this study, suggested the similar to mechanical behavior of the bulk-fill and resin-based composite materials both artificial saliva and distill aging periods. However, in this study no linear relationship was found between filler volume and surface roughness both in artificial saliva and distill aging environment.

Bu calismanin amaci korozif yapay agiz sivisi ortaminda termal cevrimin iki farkli restoratif kompozit dis dolgu malzemelerinin yuzey puruzlulugu(Ra) uzerindeki etkisinin incelenmesidir. Bu calismada Renamel Microfill ve Kuraray Clearfil AP-X kompozit dis dolgu malzemelerinden uretici firmanin onerdigi ortam kosullarinda 4 mm X 8 mm (yukseklik X cap) boyutunda 8 adet uretildi.(n=8) Uretilen numuneler korozif agiz sivisi (0.4 NaCI + .4 KCI + 0.795 CaCl 2. 2H 2 O + 0.005 Na 2 S.9H 2 O + 0.69 NaH 2 PO 4 .2H 2 O + 1 Urea (gram/litre)) ortaminda 5°C ve 55°C sicakliklar arasinda kontrol grup, 3000 ve 6000 termal cevrim testlerine maruz birakildi. Bu testler sonucunda elde edilen veriler ANOVA ve TUKEY testlerine tabi tutuldu ve anlamlilik duzeyleri yorumlandi (α

Background: The purpose of this study was to investigate two-body wear resistance and hardness of different three modern composite materials. Methods: In the conditions recommended by the manufacturer five pieces were produced from each material. All samples were kept in distill water for 1 week and determined Vickers hardness (HV) before two-body wear test. Then, two-body wear tests were performed using a computer controlled chewing simulator. In this study, the chewing simulator was programmed to provide a 2 mm vertical movement and a 0.7 mm horizontal movement. For each wear test, Al2O3 with a diameter of 6 mm was used as antagonist material. The mean volume loss of all samples after the wear tests was determined with three dimensional profilometry. In addition to a random specimen was selected from each test group and SEM images were taken for analysis of wear tracks. Mean and standard deviation values were calculated and evaluated with the one-way ANOVA. Results: The hardness values of the materials tested in this study were measured between about 49 HV and 78 HV. Significantly, lowest mean volume loss was detected for the Heliomolar at about 3.1 μm3 whereas the highest mean volume loss was detected for the Silorane at about 6.4 μm3 after 360.000 chewing cycles. Conclusions: However, among the materials tested in this study suggested correlations between HV and two-body wear resistance are not significant.

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 60°C and 90°C and relative humidity between 30% and 100% were achieved.

In the present study, the effect of hardness of contact material on fretting fatigue strength was experimentally investigated as a function of stress ratio. AZ61 magnesium alloy used in defense and transportation industries was used as the material for both the specimen and the contact pad. Two levels of hardness of contact material, 55.3 Vickers Hardness (HV) and 83.3 HV, were prepared by heat treatments. According to the results, with increasing hardness, the fretting fatigue strength decreased. The relative slip amplitude increased with increasing hardness, while the tangential force amplitude was not influenced by the hardness. It was speculated that because the local tangential stress at the contact edge increases with increasing hardness, the fretting fatigue strength decreases with increasing hardness.

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.

Sialendoscopy is a relatively new minimally invasive technique that permits direct salivary tree visualization and is important in obstructive sialadenitis management and treatment. The present study aimed to examine the sialendoscopy learning curve between March 2009 and March 2013.We compared the first and last 100 sialendoscopies performed in our department with regard to anaesthesia type, operating time, success rate, technical difficulty, major complications, and clinical improvement.General anaesthesia rates were 63% and 38% (P = 0.0004) among the first and last 100 sialendoscopies, respectively. Among the first and last 100 procedures, respectively, average operating times were 39 and 25 minutes (P = 0.00055) for diagnostic sialendoscopies and 68 and 65 minutes (P = 0.35) for interventional sialendoscopies. Successful stone extraction rates were 65% and 90.2% (P = 0.0058) among the first and last 100 procedures, respectively, while the corresponding rates of successful stenosis dilation were 92.5% and 97.1% (P = 0.27). Technical difficulty was encountered in 25% and 17% (P = 0.164) of the first and last 100 sialendoscopies, respectively. Neither group experienced major complications. All patients tolerated the procedures well and had excellent outcomes.Progressive learning regarding sialendoscopy enabled more frequent operation under local anaesthesia, thus better meeting the requirements of a minimally invasive technique. We were able to decrease the operative time in diagnostic sialendoscopy. These two factors support the inclusion of diagnostic sialendoscopy into the diagnostic panel in obstructive glandular diseases.

The present work deals with the effect of relative slip on fretting fatigue behaviour of 2014 Aluminium alloy with age-hardened conditions T4 and T6 in contact with a dissimilar mating material AISI 1045 steel, using a plane-on-plane configuration. There are a significant number of parameters influencing fretting fatigue behaviour. Relative slip value between the specimen and fretting pad is one of the most important factors. In the present study, the influence of relative slip was evaluated at different cyclic stress levels by using a fretting pad with a single pad span value of 10 mm. The results show the artificial temper T6 is more effective for improving the fretting fatigue life when compared with natural temper T4. This may be attributed to a higher microstructural barrier to the fretting fatigue crack nucleation and initiation, due to having lower values of relative slip with artificial temper T6.

The effect of hard anodizing coated 2014-T6 aluminium alloy test samples with dissimilar mating materials on fretting fatigue was investigated. Fretting fatigue configuration involved bridge-type pads on the flat specimen. Bridge-type pads were made of AISI 4140 steel. All the fretting fatigue tests were conducted under plane bending loading with a stress ratio of R = —1. Coated and uncoated specimens were compared for microhardness, surface roughness, tangential force. The specimens were tested under both plain fatigue and fretting fatigue loading at ambient temperature. Micrographs obtained from scanning electron microscope showed that hard anodizing coating had tiny cracks through the thickness of the anodized layer. The hardness of hard anodized coating was higher than that of uncoated specimens and they also exhibited lower tangential force. However, the fretted region of the hard anodizing coated specimens was rougher than that of uncoated samples and despite lower tangential forces, fatigue lives of hard anodizing coated samples were inferior to those of uncoated samples. As the hard anodizing coating had pre-existing tiny cracks and tension residual stress, cracks propagated from the hard anodizing coating through the interface into the substrate. We conclude that these may be the main reasons for inferior fretting fatigue lives compared with uncoated samples.

Background: The purpose of this study was to effect of ambient pH and different two chewing cycles of wear on restorative nanohybrid- and microhybrid-filled composite material in intraoral tribology. Methods: All specimens were stored in the artificial saliva for 7 days before the chewing tests. Then, composite specimens were subjected to chewing simulation using a computer-controlled chewing simulator (F = 50N [vertical movement 2 mm and horizontal movement 0.7 mm] 120.000 and 240.000 chewing cycles, 1.2 Hz frequency, and 37°C ambient temperature), immersed artificial saliva (about pH = 5.7), and citric acid solution (about pH = 3.2). Steatite balls were used as antagonists for every experiment chewing test cycle (d = 6 mm). Specimen's microhardness values determined with Vickers hardness method before chewing tests. Mean volume loss values were determined using noncontact three-dimensional (3D) laser scanning device. Furthermore, two-dimensional and 3D analysis of the mean volume loss wear surface of the composite material was performed both immersed artificial saliva and citric acid. Mean values and standard deviations were calculated and statistical analysis was performed using one-way analysis of variance. In addition, scanning electron microscopy analysis was performed to examine surface wear tracks. Results: The surface morphology of both composite materials was severely damaged in immersed citric acid solution. This can be explained by the more damage to the organic matrix structure of the composite material in citric acid solution than immersed artificial saliva. Conclusion: The results obtained in this study will help to understand the effect of the pH value of the third abrasive surface on the composite material in the three-body wear mechanism.

The effect of contact pressure on the fretting fatigue behaviour of 2014 Al alloy which has been solution heat treated and age hardened (T6 heat treatment) with dissimilar mating materials, was investigated. The fretting fatigue configuration involved bridge-type contact pads on a flat fatigue specimen. Specimens were made of 2014 Al alloy and bridge-type pads were made AISI 4140 steel. All the fatigue tests were conducted at a rotational speed of 5000 rpm with a rotating bending fatigue machine (R = -1), using S-N curves to evaluate the fatigue and fretting fatigue properties. The fretting fatigue strength of the material subject to a T6 heat treatment condition at 1 x 10 7 cycles was dramatically reduced, as compared to that without fretting and with as-cast. The fretting fatigue life exhibited a variable behaviour with an increase in the contact pressure. A scanning electron microscope was employed to observe the fretting scars and fracture surfaces of the specimens. This analysis showed that cracks originated at the contact surface and crack orientations were approximately ±56 ° from perpendicular to the loading direction.

The effect of a commercial hard anodizing on the fatigue property of 2014 Al alloy which has been solution heat treated and age hardened prior to the hard anodizing of approximately 10 μm in thickness have been investigated. The results indicated that fatigue life in high stress region for aluminium alloy samples hard anodized was shorter than that of the other material condition which has been solution heat treated and then age hardened (T6 heat treated), while the life in low stress region was longer than that of the material (T6 heat treated). However, such a coating to the aluminium substrate gives rise to a significant increase in fatigue strength of 107 cycle in comparison with the as cast condition, but a much less increase in comparison with T6 heat treated samples. From the microscopic point of view, it has been observed that fatigue fracture of samples hard anodized initiated in the coating in high stress region in opposition to low stress region in which fatigue fracture initiation started on the interface between coating and substrate.

The effect of tensile prestraining-induced residual stress on the fatigue life of notched steel parts was investigated. The study was performed on AISI 4140 steel. Rotating bending fatigue tests were carried out on semicircular notched specimens with different notch radii in the as-quenched and tempered conditions. Metallography of the specimens was performed by means of light optical microscopy. The finite-element method was used to evaluate the residual stress distribution near the notch region. Fatigue tests revealed fatigue life improvement for notched specimens, which changes depending on the notch radii and applied stress. Scanning electron microscopy was used to examine the fracture surfaces of the specimens.

In order to understand the fundamental fatigue behaviour of 2014 Al alloy, rotating bending fatigue tests have been carried out using materials with an as-received and four different microstructure feature produced by solution heat treating at 410, 450, 480 and 510 °C for 2 h, then quenching in cold water (at 15 °C), followed by aging at 190 °C for 7 h. Scanning electron microscopy and X-ray diffraction were carried out to characterize the structure properties resulting from different heat treatments. The fatigue test results showed that the solution temperature have very strong influence on fatigue strength. The fatigue strength at 10 7 cycles of Al alloy made by aging after solution treating temperature of 510 °C was improved by approximately 43%, compared with as cast alloy. In addition, the fractured fatigue specimens were examined using a scanning electron microscopy in order to clarify fracture initiation points.

The effect of homogenisation treatment conditions on cold deformations of aluminium alloys AA 2014 and AA 6063 was studied by the torsion test. These aluminium alloys were homogenised at 320, 370, 420 and 470 °C for 8 h. The torsion tests were performed on as-cast and homogenised alloys at the room temperature and strain rate of 2×10 −2 s −1 . The hardness were measured the Vickers hardness method and the microstructures and textures were investigated by using optical and scanning electron microscopy (SEM), and X-ray difractometry (XRD). It was observed that the homogenisation treatment affected the microstructure of the specimen tested. The secondary phases, which were large and distributed on grain boundaries, were small and spread through the grains by homogenisation treatment. Compared to as-cast, the homogenisation treatment improved the degree of the cold deformation, depending on the kind of aluminium alloy and homogenisation temperature.

Wear behaviour of age-hardened 6063 aluminium alloy was evaluated under dry sliding conditions. A certain part of the aluminium samples was solution treated at 510 °C for 2, 4, 6 and 8 h, water-quenched then aged at 180 °C for 4 h, and the other part was solution treated at 510 °C for 6 h, water-quenched then aged at 180 °C for 1, 2, 3, 4 and 5 h in a muffle furnace. The as-cast and the aged samples were fully characterised before and after the wear testing using hardness, profilometer, scanning electron microscopy (SEM), optical microscopy, X-ray diffraction, and energy dispersive detector (EDS). The wear tests using on a pin-on-disc machine showed that the aging treatments improved the wear behaviour of AA 6063 alloy compared to as-cast samples.

Nonlinear finite element analysis (FEA) was applied to the adhesively bonded Single Lap Joint (SLJ) in bending load. Two adhesives, one stiff and one flexible, with very different mechanical behaviors, and hard steel as adherend with four different thicknesses, were analyzed for the joint configuration. For comparison, experimental work was also undertaken. It was shown that adherend thickness played an important part in the joint performance; while the stiff adhesive gave stronger joint strength when using thick adherends, the opposite was the case for the flexible adhesive when using thin adherends. These results were related to the mechanical behaviors of the adhesives used. It was shown that the results from the FEA and the experimental works were in a good agreement.

Wear behaviour of induction hardened AISI 4140 steel was evaluated under dry sliding conditions. Specimens were induction hardened at 1000 Hz for 6, 10, 14, 18, 27 s, respectively, in the inductor which was a three-turn coil with a coupling distance of 2.8 mm. Normalised and induction hardened specimens were fully characterised before and after the wear testing using hardness, profilometer, scanning electron microscopy and X-ray diffraction. The wear tests using a pin-on-disc machine showed that the induction hardening treatments improved the wear behaviour of AISI 4140 steel specimens compared to normalised AISI 4140 steel as a result of residual stresses and hardened surfaces. The wear coefficients in normalised specimens are greater than that in the induction hardened samples. The lowest coefficient of the friction was obtained in specimens induction-hardened at 875 °C for 27 s.

In this study, the corrosion behavior of 90%Cu-10%Ni (C70600) cupronickel alloy in artificial seawater was investigated. The corrosion tests were conducted using a rotating cylindrical electrode at different speeds. In the experiments, free corrosion potential tests, electrochemical impedance spectrum (EIS) analysis, weight loss tests, and optic microscope observation were performed. The corrosion rate of 90%Cu-10%Ni alloy in artificial seawater increased with increasing rotation speed and time. Damage period was changed with rotation speed. It was also determined that the damage to the protective film began after 3 hours at the rotation speed of 1600 rpm, and after 3 hours at 2000 rpm, and increased with increasing time. It was determined that 1200 rpm rotation speed is better than both 1200 rpm and 1600 rpm for working conditions.

Biomaterials used in the human body to implement lost function are natural or artificial materials. Ti-6Al-4V alloy which is used as orthopedic implant is one of these materials. The performance of orthopedic implant material may be compromised when exposed to fretting fatigue loading. Some surface treatment may be used to reduce fretting fatigue damage. Ball Burnishing (BB) is one of treatments. Ball Burnishing process is a simple mechanical surface treatment used commercially. This study investigates the effects of surface treatment on the plain and fretting fatigue properties of Ti-6Al-4V. Additionally, two-stage test is applied to investigate crack initiation of fretting fatigue specimens. The test results showed that Ball burnishing process has positive effect on plain and fretting fatigue behaviour of Ti-6Al-4V implant material, Biyomalzemeler insan vücudunda fonksiyonları yerine getirmek için kullanılan doğal ya da yapay malzemelerdir. Bu malzemelerden biri ortopedik implant olarak kullanılan Ti-6Al-4V alaşımıdır. Ortopedik implant malzemesinin performansı fretting yorulmasına maruz kalarak azalabilir. Bazı mekanik yüzey işlemleri fretting yorulma ömrünü arttırabilir. Ball Burnishing (BB) bu işlemlerden bir tanesidir. Ball Burnishing işlemi kolayca uygulanabilen basit bir mekanik yüzey işlemidir. Bu çalışmada, Ti-6Al-4V alaşımının, düz yorulma ve fretting yorulma davranışı üzerine yüzey işleminin etkisini araştırılmıştır. Two-Stage test işlemi eklenerek fretting yorulma numunelerinde çatlak başlangıcının olup olmadığı gözlemlenmiştir. Sonuçlar, BB mekanik yüzey işleminin, düz ve fretting yorulma davranışlarını, önemli derecede arttığını göstermiştir

(TiAl)N and (TiAlV)N films coated on M2 high-speed tool steel were heat-treated in an argon atmosphere at temperatures of 700°C, 800°C and 900°C for 3 h. The structural and mechanical properties of the ceramic films were examined by microindentation hardness testing, X-ray diffraction (XRD) and scanning electron microscopy. Annealing at elevated temperatures led to a decrease in the hardness of the ceramic films. The magnitude of this hardness change became larger with increasing annealing temperature. Elevated temperature anneals also modified the distribution of elements in the ceramic films. XRD data show that phase transformations take place in the structure. These transformations resulted in a decrease in the hardness, residual stress and spacing between the planes of the film. The surface topography was not affected by the heat treatment.