Superhydrophobic properties of silver-coated films on copper surface by galvanic exchange reaction

Hydrophobic properties of thin nanostructured silver films produced by galvanic exchange reaction on a copper surface were studied after passivation with stearic acid. The morphology of the silver films was controlled by varying the concentration of silver nitrate in the solution. Water contact angle as high as 156° and contact angle hystérésis as low as 5° were achieved for samples obtained with initial silver ion concentration of 24.75 mM in the solution. However, a strong dependence of contact angle and contact angle hysteresis on the fractal-like morphology of the silver films was observed with the variation of silver ion concentration

Maximum Wireless Power Transmission Using Real-Time Single Iteration Adaptive Impedance Matching

Wireless power transfer (WPT) systems’ efficiency is significantly impacted by non-monotonic variations in the coupling coefficient. For very short distances or strong-coupling cases, the WPT efficiency is minimal at the natural resonant frequency, with two peaks around this frequency, known as the frequency splitting phenomenon. On the other hand, WPT capability decreases for long distances or weak coupling cases. Therefore, adaptive matching is required for WPT systems with varying distances, like wireless charging systems for electric vehicles (EVs). This paper first presents a detailed analysis of the frequency splitting phenomenon by studying the root locations of the WPT system’s transfer function. Then, a real-time fixed-frequency adaptive impedance matching (IM) method is proposed, in which the amplitude and phase of the input impedance is estimated using the average active power, the average reactive power, and the amplitude of input voltage. Unlike traditional search-and-find techniques, the proposed method calculates the optimal IM network parameters only in a single iteration, which improves the convergent speed. A scaled-down 20-Watt prototype controlled by the TMSF2812 is fabricated and used to validate the effectiveness of the proposed method over a wide range of coil-to-coil distances

Comparative Evaluation of Microtensile Bond Strength of Three Adhesive Systems

Objectives: The aim of this study was to assess the microtensile bond strength of three universal adhesives to dentin and enamel. Materials and Methods: Sixty extracted human third molar teeth were chosen and divided into six groups regarding the adhesive (G-Premio Bond, Clearfil S3 Bond or Single Bond) and tooth surface. All the applied bonding agents were universal adhesives. The teeth were polished and the adhesives were applied; then the teeth were restored with composite resin. The samples were mounted in acrylic resin and sectioned. The specimens were subjected to a universal testing machine and the microtensile bond strength was measured. The failure mode of each specimen was determined under a stereomicroscope. Data were analyzed using two-way ANOVA (α=0.05). Results: The microtensile bond strength of G-Premio Bond to enamel and dentin was 11.79±8.27 and 17.55±9.47 MPa, respectively which was not significantly different from the values in Single Bond group (15.59±10.66 and 17.19±10.09 MPa to enamel and dentin, respectively; P>0.05). However, the values for Clearfil S3 Bond were 7.11±4.23 and 7.88±8.83 MPa to enamel and dentin, respectively, which were significantly lower than the values for G-Premio Bond (P<0.05). Scanning electron microscopic (SEM) images showed that the adhesive failure was dominant in both enamel and dentin groups and in all adhesive systems. Conclusion: G-Premio Bond and Single Bond provided higher microtensile bond strength compared with Clearfil S3 Bond. Universal adhesives with their acceptable performance can be applied in self-etch mode on both enamel and dentin

Nanostructured metal surfaces and their passivation for superhydrophobic and anti-icing applications = Les surfaces nanostructurées et leur passivation pour des applications des revêtements superhydrophobes et glaciophobes

Plusieurs systèmes et infrastructures stratégiques sont affectés ou cessent de fonctionner pendant les périodes hivernales accompagnées de givrage atmosphérique. Une des méthodes couramment utilisées pour diminuer les charges de glace ou de neige est l'utilisation des produits chimiques pour abaisser le point de congélation. Cependant, ces produits doivent être appliqués pendant le givrage ou juste avant l'accumulation de la glace, ce qui est difficile en pratique. De plus, ces produits sont nocifs pour l'environnement. C'est ainsi que de nouvelles méthodes, plus efficaces et moins nocives, sont nécessaires. Une solution idéale serait de recouvrir les structures exposées de revêtements capables de réduire ou de neutraliser l'adhésion de neige ou glace aux surfaces exposées. Une surface caractérisée par un angle de contact de 150° ou plus avec les gouttelettes d'eau déposées est dite superhydrophobe. Pour obtenir une telle surface, une des solutions suggérées est la création de surfaces nanostructurées avec faible énergie de surface. De telles surfaces hydrophobes ont de nombreuses applications si elles sont durables et n'ont pas d'effets nocifs sur l'environnement. Dans cette étude, des surfaces superhydrophobes nanostructurées ont été obtenues par le recouvrement de surfaces d'aluminium ou de cuivre avec des nanoparticules métalliques. Trois colloïdes différents de nanoparticules d'argent et deux colloïdes de nanoparticules de cuivre ont été synthétisés par des méthodes de réduction chimique (chemical reduction). Il s'est avéré que les particules d'argent sont assez stables pour cette application par rapport particules de cuivre qui ne le sont pas suffisamment. Indépendamment du type de nanoparticules, des surfaces hydrophobes n'ont pas pu être réalisées avec une seule couche. En ajoutant une deuxième couche, tous les types de nanoparticules ont formé un revêtement avec d'excellentes propriétés hydrophobes, mais avec des angles de contact différents. En raison des formes similaires des nanoparticules, cette différence entre les angles de contact pourrait dépendre de la dimension de ces particules. En effet, les particules avec une taille moyenne de -263 nanometres présentent les angles de contact les plus élevés, tandis que celles avec une taille moyenne de ~195 ou de -360 nanometres présentent des valeurs plus basses. Le comportement des revêtements superhydrophobes élaborés a été étudié dans des conditions de givrage atmosphérique. Sur une surface d'aluminium protégée par un revêtement de deux couches de particules de 263 nanometres, l'adhérence de glace a été réduite jusqu'à 8.1 fois. Cette réduction de l'adhérence était de 4 fois dans le cas de substrats à base de cuivre dans les mêmes conditions. Les échantillons à base de cuivre nanostructurés ont pu garder leurs propriétés giaciophobes même après cinq essais de déglaçage

A comparison between cold dissection tonsillectomy with harmonic scalpel tonsillectomy

Introduction: This study aimed to compare operation time, intraoperative bleeding and postoperative pain between cold dissection tonsillectomy and harmonic scalpel tonsillectomy.  Materials and Methods: In this single-blinded clinical trial, 32 patients aged 14–48 were enrolled. Each patient randomly underwent tonsillectomy using the harmonic scalpel on one side and cold dissection on the other side. Operation time and bleeding volume were measured during surgery. The pain intensity level on each side was recorded on the first and seventh postoperative days.  Results: The mean volume of intraoperative bleeding was 9.59 ml on the harmonic side and 74.38 ml on the cold dissection side; which represents a significantly lower amount on the harmonic side (

Effect of Different Titanium Surface Treatments on the Adhesion Test Result: Dental Application

The aim of the study was to investigate the effect of different surface treatment of titanium (Ti) on the adhesion test results for dental application. Ti substrates roughened by 400 to 1 500-grit SiC polish papers and alumina blasting, alkali treated by 5 molar (M) NaOH and KOH solutions and heat treated at the temperature range of 400–800 °C were used in this study. The treated samples were subjected to the adhesion test. According to the results of the adhesion test, the adhesive strength showed the highest value for the blasted titanium among all polished and blasted samples. The Ti samples heated at 650 °C showed the highest adhesive strength among all heat-treated samples. Further, the adhesion test results indicated the higher adhesive strength of chemically treated samples treated by NaOH rather than that by KOH. The polished and heated Ti samples showed the highest adhesive strength among all samples