Effect of sandblasting and acid surface pretreatment on the specific capacitance of CuO nanostructures grown by hot water treatment for supercapacitor electrode applications.

Crystalline copper oxide (CuO) nanostructures with micro, nano, and micro-nano surface roughness were grown on Cu sheet substrates by a facile, scalable, low-cost, and low-temperature hot water treatment (HWT) method that simply involved immersing Cu sheet in DI water at 75 °C for 24 h without any chemical additives. Various morphological features and sizes of CuO nanostructures were tuned by using different surface pretreatment techniques including acid treatment, sandblasting, or a combination of those two. The surface morphology of the prepared samples was analyzed by scanning electron microscopy. The crystal structure of the CuO nanostructures was investigated by x-ray diffraction XRD and Raman spectroscopy. To study the pseudocapacitive behavior, their potential supercapacitor performance, and equivalent series resistance, electrochemical analysis was done by cyclic voltammetry and electrochemical impedance spectroscopy for all the CuO/Cu samples in 1 M of Na2SO4electrolyte. Among all, the best supercapacitive performance was achieved for CuO/Cu samples pretreated with Sandblasting followed by Acid treatment resulting in a specific capacitance of about 104 F g-1. The electrode with the sandblasted + acid pretreated sample showed a maximum of ∼69% capacitive retention after 2000 consecutive cycles. Our results indicate that CuO nanostructures on Cu substrates prepared with different surface pretreatment conditions and grown by HWT can be promising electrodes for supercapacitor device applications.

Influence of universal adhesives and silane coupling primer on bonding performance to CAD-CAM resin-based composites: A laboratory investigation.

OBJECTIVE: Obtaining strong resin bonds to computer-aided design and computer-aided manufacturing (CAD-CAM) resin-based composites with dispersed fillers (CCRBCs) poses a challenge. Therefore, this study aimed to assess the effect of three universal adhesives and a two-component silane coupling agent on the shear bond strength to three (CCRBCs). MATERIALS AND METHODS: Eight hundred and sixty-four specimens of Brilliant Crios, Lava Ultimate, and Tetric CAD were polished or grit blasted, bonded with Adhese Universal DC, One Coat 7 Universal (OC7), and Scotchbond Universal Plus Adhesive (SBU) with or without a silane primer. Shear bond strength was measured after 24 h and 10,000 thermocycles. Linear regressions were performed (α = 0.05). RESULTS: After thermocycling, bond strengths were similar for the universal adhesives on polished Brilliant Crios and Lava Ultimate (p ≥ 0.408). Grit blasted Tetric CAD showed no significant differences (p ≥ 0.096). The silane primer had minimal impact on grit blasted Tetric CAD (p ≥ 0.384). The silane primer increased the bond strength of OC7 to Brilliant Crios (p = 0.001) but decreased the adhesion of SBU to Brilliant Crios and Lava Ultimate (p ≤ 0.018). CONCLUSIONS: Bond strength of universal adhesives varied with CCRBC type. The two-component silane coupling agent showed mixed effects on adhesive performance. CLINICAL SIGNIFICANCE: Selecting universal adhesives from the same CCRBC product line does not always guarantee superior bond strength. The efficacy of silane coupling agents differs based on the bonding substrate.

Microshear Bond Strength, Ultramorphological, and Elemental Assessment of Gold-Silver Nanoparticle-treated Dentin Bonded to Resin Composite with Different Adhesive Modes.

AIM: The aim of the present study is to evaluate the effect of Ag-Au NPs formulation as surface pretreatment by assessing the microshear bond strength, ultra-morphological, and elemental characteristics of gold-silver nanoparticle-treated dentin to resin composite with different adhesive modes. MATERIALS AND METHODS: A total of 60 extracted sound human permanent molars were selected to test the microshear bond strength of composite resin to dentin (40 teeth) and 20 molars were used to assess the ultramorphological and elemental characteristics of silver-gold nanoparticles using environmental scanning electron microscope (ESEM) with energy-dispersive X-ray (EDX) analyzer. The specimens were randomly divided into two main groups according to measured tests either microshear bond strength or elemental analysis. For the bond-strength testing group, 40 teeth were equally distributed into two main groups (20 each) according to dentin-surface pretreatment with or without the use of silver-gold nanoparticles. Then, each group was further divided into two subgroups (10 specimens for each) according to adhesive mode. For ultramorphological and elemental analysis, 20 teeth were equally divided into similar previously mentioned groups according to treatment modalities (5 teeth per group). The multimode bonding agent used in this study was single-bond universal, 3M. The data were collected and statistically analyzed. The significance level was set at p ≤0.05. RESULTS: The results showed that different etching modes had no statistically significant effect. Also, pretreatment had no statistically significant effect. The interaction between the two variables also had no statistically significant effect. Majority of samples in all groups had mixed failure mode. Ultramorphological examination of the tested samples treated with silver-gold nanoparticles revealed proper dispersion of nanoparticles in dentin. CONCLUSIONS: The new formulation of silver-gold nanoparticles did not interfere with the bond strength and sealing ability of resin composite restoration in different adhesion modes. CLINICAL SIGNIFICANCE: The cavity disinfection with silver-gold nanoparticles did not affect the marginal integrity of resin composite restoration. Further studies should be done to evaluate the impact of application of silver-gold nanoparticles in long duration with other adhesive systems in the clinical scenario.

Surface Pretreatments of AA5083 Aluminum Alloy with Enhanced Corrosion Protection for Cerium-Based Conversion Coatings Application: Combined Experimental and Computational Analysis.

The effects of surface pretreatments on the cerium-based conversion coating applied on an AA5083 aluminum alloy were investigated using a combination of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), polarization testing, and electrochemical impedance spectroscopy. Two steps of pretreatments containing acidic or alkaline solutions were applied to the surface to study the effects of surface pretreatments. Among the pretreated samples, the sample prepared by the pretreatment of the alkaline solution then acid washing presented higher corrosion protection (~3 orders of magnitude higher than the sample without pretreatment). This pretreatment provided a more active surface for the deposition of the cerium layer and provided a more suitable substrate for film formation, and made a more uniform film. The surface morphology of samples confirmed that the best surface coverage was presented by alkaline solution then acid washing pretreatment. The presence of cerium in the (EDS) analysis demonstrated that pretreatment with the alkaline solution then acid washing resulted in a higher deposition of the cerium layer on the aluminum surface. After selecting the best surface pretreatment, various deposition times of cerium baths were investigated. The best deposition time was achieved at 10 min, and after this critical time, a cracked film formed on the surface that could not be protective. The corrosion resistance of cerium-based conversion coatings obtained by electrochemical tests were used for training three computational techniques (artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS), and support vector machine regression (SVMR)) based on Pretreatment-1 (acidic or alkaline cleaning: pH (1)), Pretreatment-2 (acidic or alkaline cleaning: pH (2)), and deposition time in the cerium bath as an input. Various statistical criteria showed that the ANFIS model (R2 = 0.99, MSE = 48.83, and MAE = 3.49) could forecast the corrosion behavior of a cerium-based conversion coating more accurately than other models. Finally, due to the robust performance of ANFIS in modeling, the effect of each parameter was studied.

Evaluation of Transverse Strength of Heat Cure Denture Bases Repaired with Different Joint Surface Contours: An In Vitro Study.

AIM: The present in vitro study aimed to evaluate the transverse strength of heat cure acrylic denture base resins repaired with three different joint surface designs, repair material being the glass-fiber-reinforced self-cure repair material along with surface pretreatment. MATERIALS AND METHODS: A total of 40 heat cure resin specimens were fabricated and finished to a size of 64 mm × 10 mm × 2.5 mm. These specimens were divided into four groups of 10 each, with butt, round, and bevel repair surface joints, respectively, along with the control group. After the specimens were cut in the middle for the repair procedure to proceed, the aforementioned joint surface contours were prepared for groups I, II, and III, respectively, treated with dimethyl chloride for 30 seconds, and the repair was done with E-glass-fiber-reinforced self-cure repair material. RESULTS: The mean transverse strength of the control group was 100.37 N, which was highest (significant p value of <0.05), followed by group III (bevel joint) 54.23 N, group I (butt joint) 53.93 N, and group II (round joint) 44.55 N. CONCLUSION: Distribution of stresses evenly in the repair region will be achieved by the proper selection of the joint surface contour, and this study showed that the 45° bevel joint was an appropriate selection along with promising repair material and surface pretreatment. CLINICAL SIGNIFICANCE: Clinically, in the event of repairing a broken denture, a rapid and economically convenient material with superior physical and mechanical properties is important to maintain the adequate transverse strength of the repaired denture. Glass-fiber-reinforced autopolymerizing resin, with a 45° bevel joint design of the broken surfaces and surface pretreatment proved to reduce stress concentration, improving the transverse strength of the repaired heat cure denture base resins.

Different surface modifications combined with universal adhesives: the impact on the bonding properties of zirconia to composite resin cement.

OBJECTIVE: The purpose of this study was to analyze the impact of plasma treatment and (universal adhesives) UAs on the bonding properties of zirconia. MATERIAL AND METHODS: Zirconia specimens (N = 744; n = 186/pretreatment) were prepared, highly polished, and pretreated: (i) plasma (oxygen plasma, 10s, 5 mm), (ii) airborne-particle abrasion (alumina, 50 µm, 0.05 MPa, 5 s, 10 mm), (iii) airborne-particle abrasion + plasma, and (iv) without pretreatment (highly polished surface). Surface roughness (Ra) and surface free energy (SFE) were measured (n = 6/pretreatment). Tensile bond strength (TBS) specimens (n = 180/pretreatment) were further divided (n = 18/conditioning): Clearfil Ceramic Primer (PCG), All-Bond Universal (ABU), Adhese Universal (AU), Clearfil Universal Bond (CUB), G-Premio Bond (GPB), Futurabond U (FBU), iBond Universal (IBU), One Coat 7 Universal (OCU), Scotchbond Universal (SBU), and no conditioning. PCG was luted with Panavia F2.0 and the remaining groups with DuoCem. After storage in distilled water (24 h; 37 °C) and thermocycling (5000×; 5 °C/55 °C), TBS was measured and fracture types (FTs) were determined. Data were analyzed using univariate ANOVA with a partial eta square (ƞP2), the Kruskal-Wallis H, the Mann-Whitney U, and the Chi2 test (P < .05). RESULTS: Plasma treatment resulted in an increase of SFE but had no impact on Ra. Airborne-particle abrasion resulted in the highest Ra and a higher TBS when compared with plasma and non-treatment. SBU and AU obtained a higher TBS when compared with PCG. OCU, FBU, ABU, IBU, and GPB indicated comparable TBS to PCG. CUB revealed the lowest TBS. CONCLUSIONS: Plasma treatment cannot substitute airborne-particle abrasion when bonding zirconia but MDP-containing adhesives are essential for successful clinical outcomes. CLINICAL RELEVANCE: Airborne-particle abrasion with a low pressure (0.05 MPa) in combination with UAs promotes the clinical success of adhesively bonded zirconia restorations.

A comparative study of the microtensile bond strength and microstructural differences between sclerotic and Normal dentine after surface pretreatment.

BACKGROUND: The resin bond strength of sclerotic dentine is significantly lower than that of the normal dentine, which paused a challenge for bonding procedures clinically. The aim of this study was to compare the effects of different surface pretreatments on the micro-tensile bond strength and microstructure between sclerotic dentine and normal dentine. METHODS: Eighty teeth that were collected, forty premolars with typical wedge-shaped defects visually graded as class III were assigned as the sclerotic dentine group (SD), the other forty normal premolars with artificial wedge-shaped defects were assigned as the normal dentine group (ND). Each group was randomly subdivided into eight subgroups according to the solution used: 35% phosphoric acid, 15% EDTA, 5% or 10% NaClO. Then the dentine surface was examined using a scanning electron microscope (SEM). The lesions were restored using self-etching adhesive and the subsequent resin composite. The teeth were sectioned into sticks for the micro-tensile bond strength analysis, and the data were analysed using the SPSS17.0 software package (α = 0.05). RESULTS: First, for the ND groups, after pretreatment using 35% phosphoric acid, and 35% phosphoric acid + 5% or 10% sodium hypochlorite, the bonding strengths of the normal dentine were higher than that of the other groups (P < 0.05). Second, for the SD groups, after pretreatment using 35% phosphoric acid, 15% EDTA, and 35% phosphoric acid + 5% or 10% sodium hypochlorite, the bonding strengths of the sclerotic dentine were higher than that of the other groups (P < 0.05). Third, the bond strengths of the sclerotic dentine were lower than that of the normal dentine without any pretreatment (P < 0.05). After pretreatment using 35% phosphoric acid + 5% or 10% sodium hypochlorite, the bonding strengths of the sclerotic dentine were higher than that of the normal dentine (P < 0.05). SEM observation showed that the appearances of dentine surface were changed after pretreatment using the above solutions, with the reduced smear layer, opened small groove and increased dentinal tubules. CONCLUSION: Pretreatment of dentine using 35% phosphoric acid+ 5% or + 10% sodium hypochlorite changed the microstructure of the sclerotic dentine surface and subsequently increased the micro-tensile bond strength.

Effect of operator skill on the dentin bonding ability of a self-adhesive resin cement after different adhesive treatments.

This study evaluated the influence of operator skill on the shear bond strength of a self-adhesive resin cement to dentin after different adhesive treatments. Flat dentin surfaces were prepared on 160 extracted molars. The teeth were distributed evenly (n = 80) to 2 groups based on the operator's skill (undergraduate dental student vs operative dentistry specialist). The teeth in each operator group were distributed into 5 groups based on pretreatments used before they were cemented to indirect composite resin cylinders with Panavia SA Luting Plus resin cement. The operators prepared the dentin surfaces for bonding according to the following pretreatment groups: 1, no treatment; 2, phosphoric acid etching; 3, Clearfil Universal Bond in etch-and-rinse mode; 4, Clearfil Universal Bond in self-etching mode; and 5, Clearfil SE Bond 2-step adhesive. After cementation was performed by the 2 operator groups, shear bond strength testing was performed, and data were analyzed with 2-way analysis of variance. The effects of operator skill and surface pretreatment and their cumulative effect were statistically significant (P < 0.05). The shear bond strength of the control group in the student group was significantly greater than that of the specialist group (P = 0.02). In group 5 (2-step adhesive), the shear bond strength of the specialist group was significantly greater than that of the student group (P < 0.001). The use of acid etching and the 3 adhesive treatments improved the bonding ability of resin cement for the expert group. This positive effect was observed only in the etch-and-rinse and self-etching modes for the student group. Extensive clinical experience did not have a positive effect on the bonding effectiveness of resin cement with no pretreatment, while the expert group showed better results in applying this cement with a 2-step adhesive pretreatment.

Antibacterial Effect of Surface Pretreatment Techniques against Streptococcus Mutans.

OBJECTIVE: The aim of this study was to evaluate the antibacterial surface pretreatment methods against Streptococcus mutans within the infected dentin surface using a tooth cavity model. MATERIAL AND METHODS: Seventy-two cavities were prepared on caries-free third molars (n = 8). After sterilization, teeth were inoculated with S. mutans for 48 h. One cavity of each tooth was used to evaluate the infection. Following inoculation, infected cavity surfaces were treated either with (1) Er:YAG Laser (1W; 5x5s, Smart 2940D Plus, Deka Laser), (2) Ozone (80s; HealOzone, Kavo), (3) ErYAG-Ozone combination, (4) Er:YAG-Ozone-CHX combination, (5) Chlorhexidine (CHX), (6) Clearfil Protect Bond (PB), (7) potassium-titanyl-phosphate (KTP) Laser (1W; 60 s, SMARTLITE D, Deka Laser), (8) KTP-Ozone combination, and (9) KTP-Ozone-CHX. Standardized amounts of dentin chips were obtained from the cavity walls, and the number of bacteria recovered was counted. Kruskal-Wallis test was used for statistical analyzes. RESULTS: Both sole antibacterial materials, CHX or Protect Bond application, exhibited the most effective antibacterial activity with 125 and 156 CFU is an acronym of "colony forming unit" usullay mentioned by acronym. (CFU/ml), respectively, among the groups evaluated (P < 0.05). Er:YAG laser irradiation and its combinations with other antibacterial surface pretreatment applications also inhibited the bacterial growth with, respectively, 1444, 406, and 294 CFU/ml bacterial recovery being more efficient than KTP laser irradiation and ozone combinations. CONCLUSIONS: As an alternative device with photodynamic effects, Er:YAG and KTP laser irradiations and their further combinations during the cavity pretreatment procedure with chlorhexidine and ozone treatments exerted antibacterial effect against S. mutans, whereas chlorhexidine and antibacterial dentin bonding application solely have the highest antibacterial effects.

Contemporary Concepts of Adhesive Cementation of Glass-Fiber Posts: A Narrative Review.

(1) Background: Cementation of glass fiber posts to root canals has been associated with various failures, especially debonding. This narrative review aims to present the contemporary concepts concerning the adhesive cementation of glass fiber post and to discuss the optimal management of these factors. (2) Methods: Electronic search was performed in MEDLINE/Pub Med and Google Scholar using selected keywords examining the parameters post length, surface treatment of glass fiber posts, post space preparation and dentin pretreatment, resin cement selection, adhesive systems and hybrid layer formation, and clinical techniques. (3) Results: The search led to the selection of 44 articles. Epoxy resin-based endodontic sealers are recommended and the use of temporary cement in the root canal should be avoided. The minimum length of a glass fiber post adhesively cemented to a root canal is 5 mm. Irrigating the root canals with chlorhexidine, MTAD, or EDTA (alone or in combination with NaOCl) after post space preparation seems to enhance the bond strength. Silane application on the surface of the post seems to be beneficial. Concerning resin cements and adhesive systems, the results were rather inconclusive. Finally, resin cement should be applied inside the root canal with an elongation tip and photoactivation should be delayed. (4) Conclusions: Contemporary concepts of adhesive cementation of glass fiber posts can indeed improve the bond between glass fiber posts, resin cement, and root canal dentin, however, evidence coming from long-term randomized prospective clinical trials is needed in order to obtain safer conclusions.

Improved procedure for square-wave voltammetric sensing of fenhexamid residues on blueberries peel surface at the anodically pretreated boron-doped diamond electrode.

BACKGROUND: Fungicide fenhexamid (FH) has a high residual concentration on fruits and vegetables, thus, it is of high importance to monitor the level of FH residues on foodstuff samples. So far, the assay of FH residues in selected foodstuff samples has been conducted by electroanalytical methods on sp2 carbon-based electrodes that are well-known to be susceptible to severe fouling of the electrodes surfaces during electrochemical measurements. As an alternative, sp3 carbon-based electrode such as boron-doped diamond (BDD) can be used in the analysis of FH residues retained on the peel surface of foodstuff (blueberries) sample. RESULTS: In situ anodic pretreatment of the BDDE surface was found to be the most successful strategy to remediate the passivated BDDE surface by FH oxidation (by)products, and the best validation parameters, i.e., the widest linear range (3.0-100.0 µmol L-1), the highest sensitivity (0.0265 µA L µmol-1) and the lowest limit of detection (0.821 µmol L-1), were achieved on the anodically pretreated BDDE (APT-BDDE) in a Britton-Robinson buffer, pH 2.0, using square-wave voltammetry (SWV). The assay of FH residues retained on blueberries peel surface was performed on the APT-BDDE using SWV, and the obtained concentration of FH residues of 6.152 µmol L-1 (1.859 mg kg-1) was found to be below the maximum residue value fixed for blueberries by the European Union regulations (20 mg kg-1). SIGNIFICANCE AND NOVELTY: In this work, a protocol based on a very easy and fast foodstuff sample preparation procedure combined with the straightforward pretreatment approach of the BDDE surface was elaborated for the first time for the monitoring of the level of FH residues retained on the peel surface of blueberries samples. The presented reliable, cost-effective, and easy-to-use protocol could find its application as a rapid screening method for the control of food safety.

Reliability and Stability Improvement of MOS Capacitors via Nitrogen-Hydrogen Mixed Plasma Pretreatment for SiC Surfaces.

We investigated the effect of nitrogen-hydrogen (NH) mixed plasma pretreatment of 4H-SiC surfaces on SiC surface properties, SiO2/SiC interface quality, and the reliability and voltage stability of metal-oxide-semiconductor (MOS) capacitors. The NH plasma pretreatment decreased the incomplete oxide and contaminants on the SiC surface and reduced the density of SiO2/SiC interface traps. Compared with the untreated sample, the dielectric insulating characteristics and reliability of samples pretreated by NH plasma were improved. We also demonstrated that the shift/hysteresis of the flat band voltage (Vfb) and the midgap voltage (Vmg) induced by bias temperature stress for SiC MOS capacitors after NH plasma pretreatment was significantly decreased. Furthermore, the mechanisms of NH plasma pretreatment to improve interface properties and device performances were determined by combining secondary ion mass spectrometry (SIMS) measurements, X-ray photoelectron spectroscopy (XPS), and first-principles calculations. The result indicates that the excessive oxidation at the SiO2/SiC interface was limited due to the reduction in the diffusion of oxygen atoms into SiC caused by the surface Si-H and Si-N; NH plasma pretreatment suppressed the generation of interfacial traps by reducing surface pollutants and passivating surface defects, and some N atoms introduced into the SiO2/SiC interface effectively passivated the interfacial electroactive traps.

Effect of Temporary Cement, Surface Pretreatment and Tooth Area on the Bond Strength of Adhesively Cemented Ceramic Overlays-An In Vitro Study.

Several viewpoints have been reported regarding the effect of temporary cements, different surface pretreatment protocols before adhesive cementation, and predictive factors. This in vitro study tested if temporary cement, pretreatment of the tooth surface, the size of enamel or dentine influence adhesive cementation to zirconia ceramics. Twenty premolars were prepared for determination of enamel and dentin area, bond strength test and failure analysis. The samples were divided into two groups: untreated prior adhesive cementation (n = 10) and with temporary cementation done, pretreated prior adhesive cementation (n = 10). Zirconia overlays (Katana Zirconia STML) were cemented on the grounded flat teeth surfaces using Panavia V5. An additional six premolars underwent dentine tubule analysis with SEM to detect temporary cement residues after temporary cementation on an untreated tooth surface (n = 3) and on a pretreated surface (n = 3). The independent sample t-test was used to compare the two groups and the means of the total tooth, dentin or enamel areas did not differ significantly between the untreated and pretreated specimens. The mean tensile bond strength was significantly (p = 0.005) higher in the pretreated specimens (337N) than in the untreated ones (204N). The overall multivariable linear regression model with three predictors (surface pre-treatment, enamel area and dentine area) was significant (p = 0.003), among which the size of enamel was the strongest predictor (ß = 0.506; p = 0.049), followed by the pretreatment effect (ß = 0.478; p = 0.001) and the size of dentin area (ß = -0.105; p = 0.022).

Current scenario on adhesion to zirconia; surface pretreatments and resin cements: A systematic review.

Several methods have been proposed to increase bonding of zirconia with resin. However, we are still to find the Holy Grail. A systematic literature review was performed through PubMed on international literature from January 2000 to May 2021 with relevant Medical Subject Headings terms. 56 articles were found to be relevant. Of all the different methods proposed, mechanochemical pretreatment of zirconia surface with alumina oxide and use of 10-methacryloyloxydecyl dihydrogen phosphate were found to be most effective as per majority of studies. New methods that require further research also surfaced.

Composite repair: On the fatigue strength of universal adhesives.

OBJECTIVES: To determine whether the composition of universal adhesives and the use of silane coupling agents could affect the fatigue strength of composite repair. METHODS: Composite samples were aged in water at 37 °C for 90 days and bonded to fresh composite to produce twin-bonded bar-shaped composite specimens (2 × 2 × 12 mm). Five universal adhesives, a multistep composite repair system and a hydrophobic solvent-free resin associated to a separate silane coupling agent application were used for bonding. Composite samples were tested under 4-pointflexure initially at quasi-static loading (n = 12) followed by cyclic loading (n = 25). The stress-life fatigue behavior was evaluated following the staircase method at 4 Hz. The unfractured side of cyclic loaded beams were evaluated under SEM to determine crack initiation sites. Fatigue data was analyzed by ANOVA and Tukey test and Wilcoxon Rank Sum Test (α = 0.05). RESULTS: Bonding protocols were unable to restore the cohesive strength of the nanofilled composite (p < 0.05). Fatigue testing was more discriminative to reveal discrepancies in composite repair than conventional quasi-static loading. While the composition of universal adhesives affected composite repair potential, the highest endurance limits occurred for the separate silane coupling agent application. Crack propagation sites were mostly located on the aged composite surface. SIGNIFICANCE: Although a trend for simplification invariably overruns current adhesive dentistry, composite repair using solely universal adhesives may result in inferior repair potential. The additonal use of silane coupling agents remains as an important procedure in composite repairs.

Effects of Proton Irradiation on the Current Characteristics of SiN-Passivated AlGaN/GaN MIS-HEMTs Using a TMAH-Based Surface Pre-Treatment.

This study investigated the combined effects of proton irradiation and surface pre-treatment on the current characteristics of Gallium Nitride (GaN)-based metal-insulator-semiconductor high-electron-mobility-transistors (MIS-HEMTs) to evaluate the radiation hardness involved with the Silicon Nitride (SiN) passivation/GaN cap interface. The impact of proton irradiation on the static and dynamic current characteristics of devices with and without pre-treatment were analyzed with 5 MeV proton irradiation. In terms of transfer characteristics before and after the proton irradiation, the drain current of the devices without and with pre-treatment were reduced by an increase in sheet and contact resistances after the proton irradiation. In contrast with the static current characteristics, the gate-lag characteristics of the device with pre-treatment were significantly degenerated. In the device with pre-treatment, the hydrogen passivation for surface states of the GaN cap was formed by the pre-treatment and SiN deposition processes. Since the hydrogen passivation was removed by the proton irradiation, the newly created vacancies resulted in the degeneration of gate-lag characteristics. After nine months in an ambient atmosphere, the gate-lag characteristics of the device with pre-treatment were recovered because of the hydrogen recombination. These results demonstrated that the radiation hardness of MIS-HEMTs was affected by the SiN/GaN interface quality.

Effectiveness of dentin pre-treatment on bond strength of two self-adhesive resin cements compared to an etch-and-rinse system: an in vitro study.

STATEMENT OF PROBLEM: It has been shown that selective etching improves the bond strength of some self-adhesive resin cements to enamel. The same has yet to be determined with dentin pre-treatment. PURPOSE: To evaluate the tensile bond strength of two self-adhesive resin cements after two dentin surface pre-treatments, and also to analyze the cement/dentin interface. MATERIAL AND METHODS: One hundred and twelve human third molars were extracted. The teeth were distributed into seven groups (n = 16). Maxcem Elite Chroma (MAX) (Kerr, Scafati, Italy) and Relyx U200 (RLX) (3M ESPE, Neuss, Germany) were used without pre-treatment or with two dentin pre-treatments (polyacrylic acid or phosphoric acid). A conventional etch-and-rinse (EAR) luting cement, NX3 Nexus (NX3) (Kerr, Scafati, Italy), was used as an external control group. Before testing, all specimens were stored in distilled water for 24 hours. Three specimens from each group were prepared for scanning electron microscopy observation (SEM). A tensile bond strength test (TBS) was performed for the remaining samples. The data were statistically analyzed using the Kruskal-Wallis test and Pairwise comparisons using the Wilcoxon rank sum test. RESULTS: MAX without pre-treatment and with phosphoric acid etching attained statistically similar bond strengths to NX3 (P > 0.05). There was a statistical difference (P = 0.00488) between RLX without pre-treatment (5.62 MPa) and NX3 (10.88 MPa). Phosphoric acid pre-treatment increases the bond strength values of RLX to a strength that is comparable to NX3 (P > 0.05). The lowest tensile bond strength (TBS) was attained after the application of polyacrylic acid with MAX (1.98 MPa). No statistical differences were found between the RLX bond strength values after polyacrylic acid treatment and RLX without pre-treatment or NX3 (P > 0.05). SEM observations disclosed an enhanced potential of the self-adhesive cements to infiltrate into dentin tubules and form resin tags when applied after phosphoric acid pre-treatment. The failure mode was dominantly adhesive. CONCLUSIONS: On dentin, the self-adhesive resin cement MAX might be an effective alternative to conventional resin cement. Etching the dentin with phosphoric acid does not have a negative effect on the bond strength of MAX to dentin. On the other hand, phosphoric acid improved the bond strength of RLX when compared to EAR cement.

Evaluation of Tensile Bonding Strength of Permanent Soft Relining Material to Denture Base Acrylic Resin after Erbium:Yttrium- Aluminum-Garnet Laser Treatment - An in vitro Study.

PURPOSE: The purpose of the study was to assess the effectiveness of erbium:yttrium-aluminum-garnet (Er:YAG) laser surface pretreatment at various pulse durations of exposure on increasing the tensile bonding strength of permanent soft relining material and acrylic resin. MATERIALS AND METHODS: Polymethyl methacrylate resin samples were fabricated and grouped as comparison group (no laser surface pretreatment) and three test groups (received Er:YAG laser surface pretreatment at various pulse durations of 10 s, 20 s, and 30 s) for bonding with the permanent soft relining material, Molloplast B. Following the surface pretreatment, the samples were tested for tensile stress using a universal testing machine. Loads at the point of failure were noted and the tensile bond strength values were obtained. Parametric tests of one-way-ANOVA and Tukey's post hoc tests were done. RESULTS: The highest tensile bonding strength was recorded in Group C, and the control group recorded the lowest bonding strength. CONCLUSION: Er:YAG laser surface pretreatment at 10 Hz, 3 W, and 300 mJ for 30 s improved the bonding strength of the permanent soft relining material to heat-processed acrylic resin material.

[Research progress in surface bonding pretreatment of dental zirconia ceramics].

Yttria stabilized tetragonal zirconia polycrystal ceramics is widely used in the field of dentistry because of its excellent mechanical properties and biocompatibility. However, it has low hydroxyl content and does not contain silica. Therefore micro mechanical retention induced by hydrofluoric acid etching on its surface is not applicable. The bonding of zirconia is a difficult problem. Zirconia surface pretreatment is commonly used to improve bonding strength and durability. This review summarizes surface pretreatment of dental zirconia ceramic including air abrasion, laser etching, acid etching, silica coating, non-thermal plasmas treatment, et al. In addition, it presents advantages and disadvantages of each treatment, provides guidance for application and future research directions.

Influence of surface pre-treatment with mechanical polishing, chemical, electrochemical and ion sputter etching on the surface properties, corrosion resistance and MG-63 cell colonization of commercially pure titanium.

The impact of four pre-treatment techniques on the surface morphology and chemistry, residual stress, mechanical properties, corrosion resistance in a physiological saline solution and cell colonization of commercially pure titanium is examined in detail. Mechanical polishing, electrochemical etching, chemical etching in Kroll's reagent, and ion sputter etching with argon ions were applied. Surface morphologies reflect the nature of surface layer removal. Significant roughening of the surface and a characteristic microtopology become apparent as a result of the sensitivity of chemical and ion sputter etching to the grain orientation. The hardness in the near surface region was controlled by the amount of residual stress. Etching of the stressed surface layer led to a reduction in residual stress and surface hardness. A compact passivation layer composed of TiO, TiO2 and Ti2O3 native oxides imparted high corrosion resistance to the surface after mechanical polishing, chemical and electrochemical etching. The ion sputter etched surface showed substantially reduced corrosion resistance, where the corrosion process was controlled by electron transfer. The specific topology affected the adhesion of the cell to the surface rather than the cell area coverage. The cell area coverage increased with the corrosion stability of the surface.