In recent years, hybrid surface treatments which include plasma nitriding combined with pre-shot peening operations have been proposed for the improvement of nitriding efficiency. The main objective ...of this study is to characterize the effects of dual process on the friction and wear behavior of metallic materials. For this purpose, AISI 4140 steel samples were shot peened at various densities of 16, 20 and 24 A. The pre-treated samples were plasma nitrided at a temperature of 500 °C for 1 and 4 h. The structural and mechanical properties of samples were analyzed by XRD, SEM and microhardness tester. Wear tests were performed under dry sliding conditions to determine the tribological properties of the samples. This study showed that the shot peening treatment formed finer grains, compressive residual stresses on the surface and increased the diffusion kinetics of the samples. The surface hardness and residual stresses increased with increasing shot peening density. It was evidence that the finer grains, increased dislocation density and surface defects increased the case depth obtained from plasma nitriding by enabling easier diffusion of nitrogen. The depth of the diffusion zones in shot peened plus plasma nitrided specimens was found almost two times thicker than that of the diffusion zones in specimens treated only by plasma nitriding. The highest surface hardness values were obtained from pre shot peened and plasma nitrided samples in consequence of the interactive effect from nitride phases/layers and increased surface compressive residual stress. As a result, pre-shot peened plus plasma nitrided samples exhibited higher wear resistance than specimens treated only by shoot peening and hybrid treating in glow a discharge atmosphere.
•Shot peening pre-treatment was applied before plasma nitriding.•Plastically deformed zones and nitride phases formed on surfaces of the material.•Shot peening enhanced the nitrogen diffusion kinetics by enabling new diffusion paths.•Wear performance of the material was improved by shot peening and plasma nitriding.
Using information gathered through analysis of screen industry–related promotion material and fieldwork conducted in Belfast in June 2017, this article traces the ways in which screen economy ...connected to James Cameron’s Titanic (1997) and HBO’s Game of Thrones and the celebratory discourse around these works brand Belfast as a dynamic global media capital. This study inquires into the ways in which association with screen industries contributes to the spatial value of a region, especially a post-industrial city that actively seeks to alter its past global image and association with a violent civil conflict. It also aims to contribute to the debate about the discourse on labor in creative cities by showing that while manufacturing labor is waning, its discourse of social welfare, hard labor, and craftsmanship transfers itself to creative industries that then justify themselves through the claim to inherit traditional industries’ economic strength, job opportunities, and work ethics.
Commercially pure titanium (CP-Ti) is commonly used as an implant material especially for orthopedic and dental treatments in biomedical applications. This material shows insufficient tribological ...properties. Some surface treatments were applied on surface CP-Ti in order to improve tribological properties of the CP-Ti. Among these techniques, sol–gel coating process was used for this purpose. In this study, CP-Ti was coated by TiO2 film with sol–gel dip coating process. Coated samples were calcined at the various temperatures. The effects of calcination temperature on the wear performance of the coated films were observed. It was observed that the hardness, elastic modulus, surface roughness, friction coefficient and wear resistance values of coated samples were higher than the uncoated CP-Ti values. Also, these properties of coated samples increased with increasing of calcination temperature. The intensity of the rutile-TiO2 phase increased with the calcination temperatures. It was determined that rutile-TiO2 structure showed self-lubrication like behavior. The best tribological properties were obtained from the sample calcinated at 900°C.
•In order to improve wear behavior of CP-Ti, sol–gel coating process was used.•TiO2 films were deposited on CP-Ti by sol–gel dip coating process and were calcined at various temperatures.•The influences of calcination temperature on wear performances of TiO2 films were investigated.
DLC films are widely used in different engineering products. However, some problems such as inadequate toughness, insufficient adhesion and internal stresses affect their performance. Therefore, we ...aimed to enhance the mechanical and tribological features of Cp-Ti by metal-free and metal-doped DLC films in this study. Cp-Ti samples were coated with un-doped and Ti, Al and V metal-doped DLC films by PVD. Their properties were investigated by Raman, XPS, XRD, SEM and wear tester. The results revealed that the incorporation of metal in DLC increased the disorder. Ti, Al and V carbides formed on DLC due to bonding of doping elements with carbon. Metal-doping improved the adhesion and decreased the internal stresses and these improvements caused metal-doped films to exhibit better tribological properties than metal-free film.
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•Metal-free and Ti, Al and V metal-doped DLC films were produced on Cp-Ti by PVD.•The sp3/sp2 ratios showed that metal doping increased the disorder in DLC.•Metal doping improved the adhesion and decreased the internal stresses in DLC.•Metal-doped DLC films exhibited better tribological than metal-free DLC film.
Objective: The aim of this study is to evaluate the effects of different types of mouthwashes (Klorhexidin, Curasept ADS 205, Meridol, Listerine Cool Citrus) on the surface roughness and color ...changes of a microhybrid (Point 4), a bulk fill (SonicFill), and a nanohybrid (Nova Compo-N) resin-based composite (RBC). Materials and Methods: Disk-shaped specimens were prepared from tested RBCs and divided into four subgroups which immersed in four different types of mouthwashes. The specimens were subjected to immersion cycles in the mouthwashes and artificial saliva (n = 8). Each cycle consisted of complete immersion in a mouthwash for 21 min and afterwards in saliva for 12 h at 37°C, and this cycle was repeated 8 times. The surface roughness was evaluated using a profilometer and coloration was evaluated using a spectrophotometer before and after immersion time. One-way analysis of variance (ANOVA) for the evaluation of surface roughness data was performed, and interrelation between groups was identified with the Sheffe's multiple comparison test. Results: There were no significant differences between the Ra values of the RBCs before and after immersion in mouthwashes (P > 0.05). There were significant differences between ΔE value of the SF and NCN groups before and after immersion time (P < 0.05). Conclusion: Mouthwashes contribute to oral health, especially in patients at high risk of caries. However, in such patients, patient-specific recommendations should be made when using mouthwashes due to the large number of composite fillings.
Geometric morphometrics is routinely used in ecology and evolution and morphometric datasets are increasingly shared among researchers, allowing for more comprehensive studies and higher statistical ...power (as a consequence of increased sample size). However, sharing of morphometric data opens up the question of how much nonbiologically relevant variation (i.e., measurement error) is introduced in the resulting datasets and how this variation affects analyses. We perform a set of analyses based on an empirical 3D geometric morphometric dataset. In particular, we quantify the amount of error associated with combining data from multiple devices and digitized by multiple operators and test for the presence of bias. We also extend these analyses to a dataset obtained with a recently developed automated method, which does not require human‐digitized landmarks. Further, we analyze how measurement error affects estimates of phylogenetic signal and how its effect compares with the effect of phylogenetic uncertainty. We show that measurement error can be substantial when combining surface models produced by different devices and even more among landmarks digitized by different operators. We also document the presence of small, but significant, amounts of nonrandom error (i.e., bias). Measurement error is heavily reduced by excluding landmarks that are difficult to digitize. The automated method we tested had low levels of error, if used in combination with a procedure for dimensionality reduction. Estimates of phylogenetic signal can be more affected by measurement error than by phylogenetic uncertainty. Our results generally highlight the importance of landmark choice and the usefulness of estimating measurement error. Further, measurement error may limit comparisons of estimates of phylogenetic signal across studies if these have been performed using different devices or by different operators. Finally, we also show how widely held assumptions do not always hold true, particularly that measurement error affects inference more at a shallower phylogenetic scale and that automated methods perform worse than human digitization.
The study addresses measurement error in 3D geometric morphometrics and, in particular, the measurement error associated with combining data from different sources. Using empirical data, we show that error can be pervasive, that typical assumptions on measurement error are not always met, and that caution is advised when combining data from multiple sources.
Drawing on in-depth interviews with users of Netflix and the local streaming service BluTV as well as analysis of press releases, and original TV series produced by these platforms, this study ...explores the emergence and impact of Video on Demand (VOD) in Turkey. It examines how VOD is adopted, negotiated, reformulated, and received in a non-Western context where global and local VOD platforms compete, substitute and emulate each other. We ask the following research question: What are Turkish audiences’ social, psychological and technological needs and expectations from global and local VOD platforms? In order to respond to this question, we explore Turkish audiences’ insight into what VOD means to them and offers them as content, in comparison with platforms’ marketing discourse. The article argues that a) the local content that platforms offer is a central juncture through which audiences articulate their larger expectations from VODs, and b) Netflix’s localization attempts do not always correspond with the audience demand, it is heavily critiqued and at times rejected by the local audience. The findings of this research indicate that the expectations, needs, and gratifications of Netflix and VOD audiences depend on three factors: Their interpretation of VODs’ local content in relation to their cultural experience with broadcast TV, their technological needs such as instant access to global content and time/space shifting opportunities, and lastly the political context and policies such as the internet regulation and censorship. The significance of this is study is in showing, as distinct from the abundant literature on localization of Netflix, the complexity of local taste. Audiences’ evaluation of a VOD is shaped simultaneously by multiple factors including their experiences with network TV, other VODs, media regulations as well as informal networks/piracy.
Simultaneous MR-PET is an increasingly popular multimodal imaging technique that is able to combine metabolic information obtained from PET with anatomical/functional information from MRI. One of the ...key technological challenges of the technique is the integration of a PET-transparent MR coil system, a solution to which is demonstrated here for a double-tuned 1 H/ 31 P head coil at 3 T. Two single-resonant birdcage coils tuned to the 1 H and 31 P resonances were arranged in an interleaved fashion and electrically decoupled with the use of trap circuits. All high 511 keV quanta absorbing components were arranged outside the PET field-of-view in order to minimize count rate reduction. The materials inside the PET field-of-view were carefully evaluated and chosen for minimum impact on the PET image quality. As far as possible, the coil case was geometrically optimized to avoid sharp transitions in attenuation, which may potentially result in streaking artefacts during PET image reconstruction. The coil caused a count rate loss of just above 5% when inserted into the PET detector ring. Except for the anterior region, which was designed to maintain free openings for increased patient comfort, an almost uniform distribution of 511 keV attenuation was maintained around the circumference of the coil. MR-related performance for both nuclei was similar or slightly better than that of a commercial double-tuned coil, despite the MR-PET coil having a close-fitting RF screen to shield the PET and MR electronics from possible electromagnetic interferences.
The evolutionary history of Mesozoic mammaliaformes is well studied. Although the backbone of their phylogeny is well resolved, the placement of ecologically specialized groups has remained ...uncertain. Functional and developmental covariation has long been identified as an important source of phylogenetic error, yet combining incongruent morphological characters altogether is currently a common practice when reconstructing phylogenetic relationships. Ignoring incongruence may inflate the confidence in reconstructing relationships, particularly for the placement of highly derived and ecologically specialized taxa, such as among australosphenidans (particularly, crown monotremes), haramiyidans, and multituberculates. The alternative placement of these highly derived clades can alter the taxonomic constituency and temporal origin of the mammalian crown group. Based on prior hypotheses and correlated homoplasy analyses, we identified cheek teeth and shoulder girdle character complexes as having a high potential to introduce phylogenetic error. We showed that incongruence among mandibulodental, cranial, and postcranial anatomical partitions for the placement of the australosphenidans, haramiyids, and multituberculates could largely be explained by apparently non-phylogenetic covariance from cheek teeth and shoulder girdle characters. Excluding these character complexes brought agreement between anatomical regions and improved the confidence in tree topology. These results emphasize the importance of considering and ameliorating major sources of bias in morphological data, and we anticipate that these will be valuable for confidently integrating morphological and molecular data in phylogenetic and dating analyses.
Diamond-like-carbon (DLC) coatings with high hardness and low friction coefficient exhibit excellent tribological performance under air and vacuum conditions. However, adhesion and cold welding ...problems in vacuum conditions lead to increase friction coefficient values. These negative effects can be eliminated by different methods such as forming interlayers between coating and substrate or ion treatment of the substrate. In this work, DLC coatings were deposited on untreated and plasma nitrided (at 400°C, 500°C and 600°C for 1h and 4h) AISI 4140 steel substrates by magnetron sputtering technique. The effects of plasma nitriding treatment on the friction and wear properties of DLC coatings under air and vacuum conditions were investigated. The structural and mechanical properties of DLC films were examined by XRD, SEM, and microhardness tester, respectively. The friction and wear properties were determined by a tribotester under air and vacuum conditions. The microhardness of samples increased after surface treatments and the highest value was obtained from the sample plasma nitrided at 600°C for 4h plus DLC coated sample. The wear resistance of samples increased with increasing plasma nitriding time and temperature. Also, it was observed that the samples tested under vacuum condition showed better wear resistance than the samples tested under ambient air. Furthermore, increasing plasma nitriding time and temperature improved the wear performance of the material regardless of the test environment.
•DLC films were produced on plasma nitrided AISI 4140 samples by magnetron sputtering.•Wear tests were performed on plasma nitrided plus DLC coated samples under air and vacuum.•The surface layer produced by DLC coating and plasma nitriding increased the surface hardness.•Plasma nitrided plus DLC coated samples exhibited excellent wear resistance under vacuum.
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