Surface Treatment Research Articles

Influence of electrophoretic deposition of micro- or nanosized silica particles on the microstructure of carbon fibers and their bond behavior with cementitious matrices

The application of carbon fiber (CF) reinforced cementitious composites is often restricted by the poor load transfer between the components. In this study, two reactive coating materials—nano-silica and micro-silica—are utilized to modify the CF surfaces via an electrophoretic deposition approach. These negatively charged particles are able to be electrosorbed onto the fiber surfaces under a constant electrical field according to the zeta and cyclic voltammetry measurements. After surface treatment, XRD analysis of CFs showed an increase in graphite crystallite thickness and decrement in interlayer spacing d002\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${d}_{002}$$\\end{document}, significantly affecting the fiber diameters. Additionally, the lengths of crystallites were reduced, which can impair the fiber strength and their temperature stability. Single fiber pullout tests exhibited that the interfacial bonding can be clearly enhanced by both reactive coatings. Microscopic observation revealed that C–S–H gel and calcite structures can be formed near the fiber surfaces after immersion in cement pore solution owing to pozzolanic reaction and nucleation effect, tremendously heightening both chemical and mechanical interaction between fiber and cement. Finally, based on a detailed micromechanical analysis, the reinforcing mechanisms between the differently modified fibers and the cementitious matrix were elaborated and discussed.Graphical abstract

Biofilm on total joint replacement materials can be reduced through electromagnetic induction heating using a portable device

BackgroundPeriprosthetic joint infection is a serious complication following joint replacement. The development of bacterial biofilms bestows antibiotic resistance and restricts treatment via implant retention surgery. Electromagnetic induction heating is a novel technique for antibacterial treatment of metallic surfaces that has demonstrated in-vitro efficacy. Previous studies have always employed stationary, non-portable devices. This study aims to assess the in-vitro efficacy of induction-heating disinfection of metallic surfaces using a new Portable Disinfection System based on Induction Heating.MethodsMature biofilms of three bacterial species: S. epidermidis ATCC 35,984, S. aureus ATCC 25,923, E. coli ATCC 25,922, were grown on 18 × 2 mm cylindrical coupons of Titanium-Aluminium-Vanadium (Ti6Al4V) or Cobalt-chromium-molybdenum (CoCrMo) alloys. Study intervention was induction-heating of the coupon surface up to 70ºC for 210s, performed using the Portable Disinfection System (PDSIH). Temperature was monitored using thermographic imaging. For each bacterial strain and each metallic alloy, experiments and controls were conducted in triplicate. Bacterial load was quantified through scraping and drop plate techniques. Data were evaluated using non-parametric Mann-Whitney U test for 2 group comparison. Statistical significance was fixed at p ≤ 0.05.ResultsAll bacterial strains showed a statistically significant reduction of CFU per surface area in both materials. Bacterial load reduction amounted to 0.507 and 0.602 Log10 CFU/mL for S. aureus on Ti6Al4V and CoCrMo respectively, 5.937 and 3.500 Log10 CFU/mL for E. coli, and 1.222 and 0.372 Log10 CFU/mL for S. epidermidis.ConclusionsElectromagnetic induction heating using PDSIH is efficacious to reduce mature biofilms of S aureus, E coli and S epidermidis growing on metallic surfaces of Ti6Al4V and CoCrMo alloys.

Effect of Hydrothermal, Chemical, and Mechanical Degradation on Flexural Strength and Phase Transformation of Ground, Glazed, and Polished Zirconia

Objectives: Evaluation of the effect of grinding on flexural strength of zirconia after low temperature degradation (LTD) and pH-cycling. Materials and Methods: Sixty-four bar-shaped specimens of yttria-stabilized tetragonal polycrystalline zirconia were milled, sintered, wet-polished, and divided into 8 groups (N=8). The four control groups were not aged while artificial aging was performed in the 4 experimental groups in three steps including LTD in steam for 40h, pH-cycling, and tooth brushing for artificial aging. All groups underwent surface preparations as follows: standard polishing without surface treatment (Sp), grinding with a blue-yellow band diamond instrument (Gr); grinding with a diamond rotary instrument (DRI) and then over-glazing (Gl); grinding with a DRI followed by two-step intraoral polishing (Po); standard polishing and aging (Sp-Ag); grinding and aging (Gr-Ag), grinding, over-glazing and aging (Gl-Ag); and grinding, polishing and aging (Po-Ag). Monoclinic content was assessed in one specimen of each group by X-ray diffraction (XRD). The 3-point flexural strength test was performed in a universal testing machine. The results were analyzed with two-way ANOVA and Tukey’s test (α=0.05). Results: Mean flexural strength (Mpa) was significantly higher in groups Gr and Po compared to group Sp (both, P<0.0001) and group Gl (both, P<0.0001). In XRD analyses, the highest monoclinic phase before aging was observed in group Gr (12.6%), and after aging in group Gr-Ag (51.2%). Conclusion: Grinding and polishing increased the flexural strength, while glazing did not exhibit any significant effect on this parameter. Furthermore, aging did not adversely affect flexural strength.

Enhancement of flow boiling heat transfer characteristics on diamond/Cu heterogeneous surface

Surface treatment is an effective method of enhancing the heat transfer performance of flow boiling. Nonetheless, the majority of existing studies on surface treatment primarily concentrated on homogeneous materials and their associated zone design. Diamond/Cu, as a particle‐reinforced composite, exhibits heterogeneous surface properties and surface microstructures that play distinct roles in the heat transfer. To elucidate the synergistic effect of heterogeneous material surfaces and microstructures, pure copper surface (PC), untreated diamond/Cu surface (DC), and surface‐treated diamond/Cu surface (SDC) were prepared for this experiment. These surfaces demonstrate various combinations of diamond, copper, and their corresponding surface microstructures. DC, characterized by heterogeneous wetting properties, demonstrates a heat transfer coefficient that is 9%–24% higher than that of PC. No trend of decreased heat transfer capacity is observed in DC. The surface treatment of SDC results in the formation of a superhydrophilic CuO nanosheet structure, significantly enhancing both surface roughness and energy. SDC develops microcracks on the surface of diamond. The increased roughness provides numerous nucleation area for the hydrophobic diamond, enhancing the overall wettability of the surface when combined with the superhydrophilic CuO region. SDC demonstrates the advantage of enhanced flow boiling on the surface of heterogeneous materials. At the identical heat flux, SDC exhibits a reduction of 5 °C–10 °C in wall superheat and an increase of 38%–47% in heat transfer coefficient.This article is protected by copyright. All rights reserved.

Controlled epitaxy and patterned growth of one-dimensional crystals via surface treatment of two-dimensional templates

Mixed-dimensional van der Waals (vdW) heterostructures offer promising platforms for exploring interesting phenomena and functionalities. To exploit their full potential, precise epitaxial processes and well-defined heterointerfaces between different components are essential. Here, we control the growth of one-dimensional (1D) vdW microwires on hexagonal crystals via plasma treatment of the growth templates. AgCN serves as a model 1D system for examining the dependence of the nucleation and growth parameters on the surface treatment conditions and substrate types. The oxygen-plasma-treated transition metal dichalcogenides form step edges mediated by formation of surface metal oxides, leading to robust AgCN epitaxy with an enhanced nucleation density and low horizontal growth rates. Monte Carlo simulations reproduce the experimentally observed growth behaviors and unveil the crucial growth parameters, such as surface diffusivity. The plasma treatment results in distinct effects on graphite and hexagonal boron nitride templates, which undergo plasma-induced amorphization and deactivation of the AgCN vdW epitaxy. We achieve the selective growth of AgCN microwires on graphite using the deactivated vdW epitaxy. This study offers significant insights into the impact of surface treatment on 1D vdW epitaxy, opening avenues for controlled fabrication of mixed-dimensional vdW heterostructures.

Use of Laser Texture Scanner to Control Quality of Chip Seal Construction

Chip seal is a pavement surface treatment, consisting of a combination of asphalt binder or emulsion and a layer of aggregate compacted on top of a pavement substrate. Raveling and bleeding are the two major distresses that affect the performance of chip seals. Studies have shown that these distresses can be related to the embedment depth, among a few factors. Embedment depth is the depth that rock is lodged into binder and is a key parameter that significantly affects the performance of chip seals. Currently, embedment depth is evaluated by pulling out the rock from the binder (often by a plier) and visually estimating the percentage of embedment. However, this method is subjective and does not provide accurate and reliable results. This study evaluated the use of laser texture scanner as quality control of chip seal construction. The mean profile depth (MPD), which is inversely related to percent embedment in the field, was measured and used to correlate with chip seal performance for raveling and bleeding. It was found that MPD is sensitive to compaction efforts of chip seals. The shoulder MPD value of chip seals after sweeping should be at a minimum of 0.150 in. to prevent bleeding from happening for the traffic volume experienced by the selected field project. When MPD in the wheelpath drops below 0.05 in., bleeding has occurred. More field experiments are needed to cover different construction practices and conditions to validate the findings from this study.

The impact of different surface treatments on repair bond strength of conventionally, subtractive-, and additive-manufactured denture bases.

This study aimed to examine the shear bond strength (SBS) of repair material to conventionally, subtractive-, and additive-manufactured denture bases after different surface treatments. Disk-shaped test specimens (N = 300) were prepared from denture base materials produced by one conventional (Procryla), one subtractive (Yamahachi), and one additive (Curo Denture) method. The test specimens were randomly divided into five groups (n = 10) and exposed to a variety of surface treatments-Group A: no surface treatment; Group B: grinding with silicon carbide paper; Group C: sandblasting; Group D: erbium: yttrium-aluminum-garnet laser; and Group E: plasma. Repair was performed with autopolymerizing acrylic resin (Meliodent). Surface roughness analyses were performed with a profilometer. Scanning electron microscopy was used to examine one specimen from each subgroup. SBS was evaluated on a universal testing machine. Failure types were observed under a stereomicroscope. Surface roughness values were significantly higher in all test materials in Group D than in the other groups (p < 0.001). For conventional resin, the SBS values were higher in Group C than in Groups A, D, and E (p < 0.001). For CAD/CAM material, Groups B and C had significantly greater SBS increases compared with Group E (p < 0.001). For 3D material, Group D showed higher SBS than all groups except Group C (p < 0.001). For SBS, sandblasting was most effective in the conventional group, whereas laser treatment was the most effective in the additive-manufactured group. For the subtractive group, surface treatments other than plasma exhibited similar SBS. In repairing fractured prostheses, any degree of roughening suitable for the material content may provide an SBS benefit.

Enhanced Copper Bonding Interfaces by Quenching to Form Wrinkled Surfaces

For decades, Moore’s Law has been approaching its limits, posing a huge challenge for further downsizing to nanometer dimensions. A promising avenue to replace Moore’s Law lies in three-dimensional integrated circuits, where Cu–Cu bonding plays a critical role. However, the atomic diffusion rate is notably low at temperatures below 300 °C, resulting in a distinct weak bonding interface, which leads to reliability issues. In this study, a quenching treatment of the Cu film surface was investigated. During the quenching treatment, strain energy was induced due to the variation in thermal expansion coefficients between the Si substrate and the Cu film, resulting in a wrinkled surface morphology on the Cu film. Grain growth was observed at the Cu–Cu bonding interface following bonding at 300 °C for 2 and 4 h. Remarkably, these procedures effectively eliminated the bonding interface.

Corrosion Enhancement of PM Processed Magnesium by Turning Native Oxide on Mg Powders into Carbonates

In addition to its use as a lightweight material, pure magnesium is a promising candidate for prospective bioimplants considering its excellent biocompatible properties. Regardless of what Mg application is used, the ultimate goal is to improve magnesium's mechanical properties and degradation behaviour. Because of the high affinity for oxygen native oxide layer of gas-atomized powders is naturally formed in contact with the atmosphere. S/TEM investigation of the native oxide of the Mg powder particles revealed a nonhomogeneous nano-crystalline MgO layer. MgO is relatively soluble in water and does not provide sufficient corrosion protection. Among various surface treatment methods, conversion of the non-protective magnesium oxide to carbonate products is possible depending on the environmental conditions. This work used a simple experimental method using CO2 and water vapour to achieve surface carbonation of Mg powders. Two carbonated samples and pure magnesium were prepared by direct extrusion. The samples after carbonation retained good mechanical properties and the layer of carbonates had a significant impact on corrosion resistance. 1 day carbonation resulted in transformation of native oxide into amorphous layer and reduction of corrosion rate. Longer carbonation (10 days) revealed layer growth and transformation of native oxide to crystalline nesquehonite structure.

Implant surface modifications and their impact on osseointegration and peri-implant diseases through epigenetic changes: A scoping review.

Dental implant surfaces and their unique properties can interact with the surrounding oral tissues through epigenetic cues. The present scoping review provides current perspectives on surface modifications of dental implants, their impact on the osseointegration process, and the interaction between implant surface properties and epigenetics, also in peri-implant diseases. Findings of this review demonstrate the impact of innovative surface treatments on the epigenetic mechanisms of cells, showing promising results in the early stages of osseointegration. Dental implant surfaces with properties of hydrophilicity, nanotexturization, multifunctional coatings, and incorporated drug-release systems have demonstrated favorable outcomes for early bone adhesion, increased antibacterial features, and improved osseointegration. The interaction between modified surface morphologies, different chemical surface energies, and/or release of molecules within the oral tissues has been shown to influence epigenetic mechanisms of the surrounding tissues caused by a physical-chemical interaction. Epigenetic changes around dental implants in the state of health and disease are different. In conclusion, emerging approaches in surface modifications for dental implants functionalized with epigenetics have great potential with a significant impact on modulating bone healing during osseointegration.

Optimizing the surface quality of heat-treated 2Cr13 stainless steel via electrochemical machining

The improvement of mechanical properties and surface quality was of great significance for materials. In this study, 2Cr13 stainless steel was subjected to the quenching and tempering treatment. The electrochemical machining approach was adopted for surface treatment. The results showed that the quenching and tempering treatment improved the Vickers microhardness of 2Cr13 stainless steel. The enhancement of microhardness was facilitated by the formation of tempered sorbite and grain refinement. Electrochemical machining provided high quality surfaces. The heat-treated workpice had more advantages in electrochemical machining efficiency. The polarization curves proved a downward shift of the self-corrosion potential for the heat-treated 2Cr13 stainless steel, which was strongly related to the electrochemical behavior. A mechanism model for promoting anode electrochemical dissolution was proposed.

Optimizing mechanical and durability properties of recycled aggregate concrete using pozzolanic slurries and modified mixing approach

A sustainable and reliable methodology to strengthen the mortar adhered to recycled concrete aggregate (RCA) is crucial for optimizing its utilization in construction. This research proposes a mortar strengthening method by soaking RCA in different dosages (weight percentages) of pozzolanic slurries, i.e., fly ash and silica powder (F-S), fly ash and cement (F-C), cement and silica powder (C-S) for various durations. The influence of each slurry dosage and soaking duration on RCA's physical and mechanical properties and surface morphology were examined. Further, a modified two-stage mixing approach (M-TSMA) was employed to produce recycled aggregate concrete (RAC) incorporating 100% untreated and surface-treated RCA. The impact of M-TSMA and treated RCA on concrete was demonstrated regarding its mechanical and durability properties, such as compressive strength, ultrasonic pulse velocity, rebound hammer, sorptivity, and resistance to chloride ions. Results show that soaking RCA in 30% C-S slurry for 6 h enhances RCA's overall properties by increasing the calcium silicate hydrate (C-S-H) content. Moreover, employing M-TSMA and incorporating treated RCA improves the mechanical and durability properties of RAC by reducing microcracks and densifying the microstructure. Overall, the proposed surface treatment and M-TSMA can potentially enhance RAC performance with complete RCA utilization.

Effect of Acid Surface Treatments on the Shear Bond Strength of Metal Bracket to Zirconia Ceramics

The surface treatment of zirconia prior to bonding remains controversial and unclear. This study aimed to compare the shear bond strength (SBS) of metal brackets to zirconia under surface treatments with either 4% HF or 37% PA in both immediate loading (IML) and artificial aging by thermocycling (TMC). Methods: Eighty-four zirconia were randomly assigned to six groups based on the surface treatment and artificial aging by TMC: (1) No surface treatment (NT); (2) NT + TMC; (3) HF (4% HF for 2 min); (4) HF + TMC; (5) PA (37% PA for 2 min); and (6) PA + TMC. After bracket bonding, only the TMC groups were thermocycled for 5000 cycles. The SBS and adhesive remnant index (ARI) of all groups were analyzed (p &lt; 0.01). Results: TMC significantly lowered the SBS more than the IML in all acid surface treatment groups (p &lt; 0.01). The ARI score after TMC was significantly higher than the IML in all acid surface treatment groups (p &lt; 0.001). No significant differences in the SBS values or ARI scores were observed among the surface treatments (p &gt; 0.01). Conclusions: Two-minute simple etching methods, using either 4% HF or 37% PA, showed an insufficient SBS of metal orthodontic brackets to zirconia after TMC.

The Effect of Different Chemical Surface Treatments on the Bond Strength of Resin-Matrix Ceramic Repaired with Resin Composite.

This study investigates the effect of different chemical surface treatment protocols with different functional monomers of universal adhesives on the shear bond strength between resin-matrix ceramic and resin composite. Eighty resin-matrix ceramics (Shofu block HC) were built and designed into eight groups of ten specimens and surface treated with HC primer (HC) and/or three universal adhesives (single bond universal [SBU], Scotchbond universal plus [SBP], and Tetric N-bond universal [TNU]) assigning follows; group 1, nonsurface treated; group 2, HC; group 3, SBU; group 4, HC + SBU; group 5, SBP; group 6, HC + SBP; group 7, TNU; group 8, HC + TNU. A template was put on the specimen center, and then pushed packable resin composite. Mechanical testing machinery was used to examine the samples' shear bond strength (SBS) values. To examine failure patterns, the debonded specimen surfaces were examined by a stereomicroscope. The one-way analysis of variance method was used to evaluate the data, and the Tukey's test was used to determine the significant level (p < 0.05). The highest SBS was obtained in group 6 (39.25 ± 1.65 MPa). Group 1 (4.15 ± 0.54 MPa) had the lowest SBS. Group 6 exhibited the highest percentage of cohesive failure patterns (70%). High SBS values were frequently correlated with the surface treatment groups and the cohesive failure patterns. The application of HC primer prior to the universal adhesive is an alternative protocol for enhancing the repair bond strength between resin-matrix ceramic and resin composite interfaces. Moreover, the application of HC primer prior to the SBP is the best strategy for resin-matrix ceramic and resin composite repairs.

Metal Fragments of Roman Pipes from Pompeii: Investigations on Copper-Based Alloys, Corrosion Products, and Surface Treatments

This work reports the study of metal fragments from Roman pipes excavated from the archaeological site of Pompeii and currently preserved in the deposits of the National Archaeological Museum of Naples (MANN). The Roman pipe, called the tibia, is a reed wind musical instrument similar to the Greek aulos. It can be made of wood, bone, and/or metal. Materials consisting of metal Cu-based alloys were excavated from archaeological burial environments. This research aims to identify the composition of the alloys, characterize the corrosion patinas, and identify any ancient surface treatments on the fragments. Non-invasive and micro-invasive techniques were used to achieve this aim, i.e., optical microscopy, Raman spectroscopy, attenuated total reflectance Fourier-transform infrared spectrophotometry, scanning electron microscopy, and energy dispersive spectrometry. This research contributes to a deeper understanding of the materials and manufacturing techniques used for these instruments, as well as the degradation processes occurring over the centuries.

New strategy for structure rearrangement of thin-film composite (TFC) polyamide (PA) membranes and offering potential use in both aqueous and organic solvents

The purity of sodium hexafluorophosphate (NaPF6) is crucial for the preparation of electrolytes in manufacturing. We propose a simple process in order to induce membrane structure rearrangement process (SRP) by activating thin-film composite (TFC) membranes with polyamide (PA) structure and explore their potential green recycling application in concentrating sodium-ion batteries (SIBs) electrolyte. The method utilizes a solution containing polar aprotic solvent as the soaking and activating solution to swell and disintegrate the loosely cross-linked PA layer, and a non-solvent solidification solution complete the SRP, enhancing the permeability of the PA layer while maintaining high rejection rates for divalent ions. Subsequently, during the further treatment of the membrane surface in structure rearrangement, tert-butanol (TBA) is introduced into the aqueous solution to reconstruct the surface PA layer, further improving the permeability. The optimal D8010T10 achieved a permeation flux of 24.2 L m−2 h−1·bar−1, with rejection rates for sodium sulfate (Na2SO4), magnesium chloride (MgCl2), and magnesium sulfate (MgSO4) reaching 94.7 %, 98.4 %, and 99.1 % respectively. And the mechanism of SRP with different solvent is analyzed and explained through dissipative particle dynamics (DPD) simulations. This study provides a commercially viable approach for manufacturing high-performance membranes. The D8010T10 membrane achieves more than 90 % separation efficiency for sodium hexafluorophosphate (NaPF6) dissolved in different solvents, providing a potential solution for the concentration and recovery of NaPF6 in lab-scale, verified its potential use in the organic solvent nanofiltration (OSN) and a path way for waste membrane recycling and degrading use in the industry.

Preparation of Silane-Treated Eggshells Polyvinyl Chloride Films by Co-Precipitation: Effect of Vinyltrimethoxysilane Surface Treatment on the Tensile Properties

Waste eggshell powders with a particle size of less than 0.315 μm were surface treated with vinyltrimethoxysilane. XRD, FT-IR, BET and SEM analyses were used to determine the surface characteristics of eggshells before and after silane treatment. The preparation of films of unplasticized suspension polyvinyl chloride with untreated and silane-treated eggshells was done by co-precipitation of solutions from cyclohexanone. The tensile properties of obtained films containing vinyltrimethoxysilane-treated eggshell powders were investigated and analyzed relative to the compositions with untreated powders.

Low-loss α-tantalum coplanar waveguide resonators on silicon wafers: fabrication, characterization and surface modification

Abstract The performance of state-of-the-art superconducting quantum devices is currently limited by microwave dielectric loss at different interfaces. α-tantalum is a superconductor that has proven effective in reducing dielectric loss and improving device performance due to its thin low-loss oxide. Here, we demonstrate the fabrication of high-quality factor α-tantalum coplanar-waveguide resonators directly on pristine 300 mm silicon wafers over a variety of metal deposition conditions and perform a comprehensive material and electrical characterization study. Additionally, we apply a surface treatment based on hydrofluoric acid that allows us to modify different resonators surfaces, leading to a reduction in two-level system (TLS) loss in the devices by a factor of three. This loss reduction can be entirely attributed to the removal of surface oxides. Our study indicates that large scale manufacturing of low-loss superconducting circuits should indeed be feasible and suggests a viable avenue to materials-driven advancements in superconducting circuit performance.

Bone-to-Implant Contact in Implants with Plasma-Treated Nanostructured Calcium-Incorporated Surface (XPEEDActive) Compared to Non-Plasma-Treated Implants (XPEED): A Human Histologic Study at 4 Weeks

Bone-to-Implant Contact in Implants with Plasma-Treated Nanostructured Calcium-Incorporated Surface (XPEEDActive) Compared to Non-Plasma-Treated Implants (XPEED): A Human Histologic Study at 4 Weeks

Enhanced performance of HTM-free perovskite solar cells with free-standing carbon electrode via surface treatment and conductive support

This study explores the optimization of hole transport material (HTM)-free perovskite solar cells featuring laminated free-standing carbon film as a back electrode. Surface treatment of perovskite film using different types of solvent (chlorobenzene, toluene, and ethyl acetate) was carried out to improve the electrical contact at the carbon/methylammonium lead iodide interface. Overall, the surface treatment improved mechanical adhesion between the perovskite and carbon film. The conductivity of the free-standing carbon electrode was further improved by attaching the carbon film to various types of conductive support. Our results show that the selection of both solvents used during surface treatment and the type of conductive substrate has a considerable impact on the resulting performance, wherein all modifications gave rise to substantial improvement over the benchmark unmodified carbon electrode. A power conversion efficiency (PCE) of 7.74% was achieved by the perovskite solar cell with laminated carbon electrode on Al foil combined with the application of chlorobenzene as surface treatment, demonstrating a tremendous increase in performance compared to that of untreated free-standing carbon electrode that produced PCE less than 1%. The main contributor to the improved performance is presumably due to the low carrier recombination rate and improved charge carrier extraction as implied by the electro-impedance spectroscopy and photoluminescence analysis. This work demonstrates a facile approach for resolving the challenges in developing low-cost HTM-free perovskite solar cells with a free-standing carbon film electrode.