In Situ Stress Measurement During Aluminum Anodizing Using Phase-Shifting Curvature Interferometry

Stress measurements yield insight into technologically relevant deformation and failure mechanisms in electrodeposition, battery reactions, corrosion and anodic oxidation. Aluminum anodizing experiments were performed to demonstrate the effectiveness of phase-shifting curvature interferometry as a new technique for high-resolution in situ stress measurement. This method uses interferometry to monitor surface curvature changes, from which stress evolution is inferred. Phase-shifting of the reflected beams enhanced measurement sensitivity, and the separation of the optical path from the electrochemical cell in the present system provided increased stability. Curvature changes as small as 10−3 km−1 were detected, at least comparable to the resolution of state-of-the-art multiple beam deflectometry. It was demonstrated that small curvature change rates of 10−3 km−1s−1 could be reliably measured, indicating that the technique can be applied to bulk samples. The dependence of the stress change during anodizing on current density (tensile at low current density, but increasingly compressive at higher current densities) was quantitatively consistent with earlier multiple-beam deflectometry measurements. The close similarity between the results of these different high-resolution measurements helps to resolve conflicting reports of anodizing-induced stress changes found in the literature

Senkronize bilateral üst üriner sistem ürotelyal karsinomu olgu sunumu]

Synchronous bilateral upper urinary tract urothelial cancer (UTUC) is a very rare form of urothelial cancer. In patients with high-risk unilateral UTUC, radical nephroureterectomy (RNU) is the gold standard treatment. However, there is no consensus on the treatment for synchronous bilateral UTUC. Evaluation of the patient and the tumor is recommended. Bilateral nephron-sparing surgery (NSS) was performed on a 53-year-old patient who presented with high-risk synchronous bilateral UTUC, and the outcome was reported

Stress evolution of anodic alumina films prior to the pore formation

Porous anodic oxide (PAO) films are grown by electrochemical oxidation of metals in a solution that dissolve the oxide. During the film formation, voltage increases linearly until the peak, then declines to steady-state value. PAO finds extensive usage as templates and substrates in many applications, such as solar cells and optical devices. However, the mechanism underlying the observed initiation and evolution of self-organized PAO structure is not understood. Recent studies on pore formation points out the role of plastic flow on pore initiation process [1–3]. In this study, we characterized stress profiles and its evolution during the film formation prior to the pore initiation. Phase-shifting curvature interferometry was used to monitor sample curvature change during film growth and subsequent dissolution. Oxide films were grown at constant current densities in 0.4 M H3PO4 until different thicknesses and subsequently current was turned off to dissolve grown oxide film. The stress profile of oxide film was revealed by in-situ monitoring the curvature change during dissolution of oxide film period after anodizing [4] . In addition, morphological evolution of oxide film during film growth was characterized using SEM. Oxide films growth until different thicknesses values up to onset of pore initiation instability. The measured stress change during film growth was in excellent agreement with prior measurements [5]. Measured stress profiles showed that for thin films \u3c20 nm, compressive stress was evenly dispersed through the thickness. However, for thicker films, the stress is concentrated within 20-nm thick layer near the solution interface. Transition in the stress profile coincides with oxide film thickness associated with initial roughening instability at the solution interface [6]. SEM images also showed that the first instability initiated at an oxide thickness of 20 nm with stable surface roughness pattern with a length scale of 20 nm. After the initial instability, the stress level near the solution interface became increasingly compressive as oxide film thickens. This behavior continued until the moment of self-ordered pore initiation when the both oxide thickness and the integrated oxide stress rapidly decreased to steady-state values. Morphological change during anodizing coincides with the stress transient, which could be attributed to the relaxation of elastic stress due to onset of plastic flow. Thus, plastic yielding in the oxide may induce a second instability mechanism involving pore initiation, leading to final self-ordered pore pattern. ACKNOWLEDGMENTS Support was provided by the National Science Foundation (CMMI-100748). REFERENCES [1] Garcia-Vergara, S.J., et al. Electrochim. Acta. 2006, 52, 681. [2] Houser, J.E., Hebert, K.R. Nature Mater. 2009, 8, 415. [3] Oh, J., Thompson, C.V. Electrochim. Acta. 2011, 56, 4044. [4] Çapraz, Ö.Ö., Shotriya, P., Hebert, K.R. J. Electrochem. Soc. 2014, 161, D256. [5] Çapraz, Ö.Ö., Hebert, K.R., Shotriya, P. J. Electrochem. Soc. 2013, 160, D501. [6] Hebert, K.R., et al. Nature Mater. 2012, 11, 162

Retrospective evaluation of patients admitted to Karadeniz Technical University Pediatric Dentistry clinic due to trauma

Purpose Traumatic dental injuries are among the commonly observed problems in the primary and permanent teeth. The rate of prevalence of dental trauma varies globally. In this study, we investigated the type of dental trauma, related factors, and treatment procedures in children. Subjects and Methods During a 5-year period (January 2011–January 2016), 416 children aged in the range of 1–15 years were admitted to our clinic with dental trauma. The cause and type of the dental trauma in the primary and permanent teeth and their relation with gender and age were evaluated using the chi-square test, and their distribution by age was evaluated using regression analysis. Results Overall, girls and boys comprised 37% and 63% of the study population, respectively. The mean age was 8.5 years. Falls (61.1%) were the most common cause of traumatic dental injuries, and enamel–dentin fracture (26%) was the most common dental trauma type. Conclusions Traumatic dental injuries in children are common. A large proportion of patients without any clinical symptoms (15.8%) did not seek any treatment after the trauma. Teachers, parents, and children should be informed about the action to be taken when dental trauma occurs and about the importance of immediately taking the child to a dentist after the trauma to ensure an accurate diagnosis, an optimal treatment plan, and positive outcome