Increased Surface Wettability Research Articles

Surface characteristics and in vitro biocompatibility of surface-modified titanium foils as a regenerative barrier membrane for guided bone regeneration.

This study evaluated surface characteristics and biocompatibility of surface-modified thin titanium (Ti) foils as a regenerative barrier membrane for future application in guided bone regeneration (GBR) surgery to augment atrophic alveolar bone. Anodic oxidation and post-heat treatment were performed to prepare various Ti foil samples. Then, the in vitro soft and hard tissue compatibility of the samples was evaluated by examining the cell responses using primary human gingival fibroblasts (HGFs) and MG63 human osteoblast-like cells. Investigated Ti foil samples showed marked differences in physicochemical surface properties. Additional 400°C heat treatment applied to the anodized Ti surface led to formation of an anatase titanium dioxide structure and well-organized nanoscale protrusions, and significantly increased surface wettability. Anodization and heat treatment enhanced the growth of HGFs and MG63 cells in Ti foil samples. Additional heat treatment for 10 and 30min further significantly improved the response of HGFs including spreading and proliferation, and upregulated the mRNA expression of cell adhesion- and maturation-related genes as well as the osteoblast differentiation of MG63 cells. Ti foil sample with thin oxide coating obtained by a 30min heat treatment exhibited poor clinical plasticity as a regenerative barrier membrane, which showed complete coating failure in the bending test. Our results indicate that anatase Ti oxide coating of a specific film thickness with nanoscale surface protrusion morphology and hydrophilic characteristics obtained by anodization and post-heat treatment would be an effective approach as a biocompatible Ti regenerative membrane for inducing better regeneration of both gingival tissue and bone.

The effect of polyethylene glycol on printability, physical and mechanical properties and osteogenic potential of 3D-printed poly (l-lactic acid)/polyethylene glycol scaffold for bone tissue engineering

One of the challenges in critical size bone defect repairing is the use of a porous degradable scaffold with appropriate properties to the host tissue. Nowadays, the three-dimensional (3D) printing method can produce custom and personalized scaffolds and overcome the problems of traditional methods by controlling the porosity and dimensions of biomaterial scaffolds. In this study, polylactic acid/polyethylene glycol (PLA/PEG) scaffolds were prepared with different PEG percentages (0, 5, 10, 15 and 20 wt%) by fused deposition modeling (FDM) to optimize printability and achieve suitable physico-mechanical properties and also enhance cellular behavior for bone tissue engineering and actually, this study complements previous studies. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were employed for chemical, morphological and thermal evaluations, respectively. It was shown that the adding of 20 wt% PEG to PLA 3D printed scaffolds reduced water contact angle (from 78.16 ± 3.27 to 60.00 ± 2.16), and increased surface wettability. The results also showed that the mechanical properties of the printed scaffolds were not significantly reduced by adding 5 and 10 wt% of PEG. The addition of PEG increased the degradability of scaffolds during immersion in phosphate buffer saline (PBS) solution for 8 weeks and PLA/PEG20 scaffold with 50.96 % had the highest rate of degradation. MTT assay showed that none of the studied scaffolds had cytotoxicity against MG-63 cells and increasing the PEG levels to 20 wt%, increased cell viability and adhesion and osteogenic differentiation. According to the obtained physical, mechanical and biological results, PLA/PEG scaffold printed by the FDM method can be an appropriate candidate for use in bone repair applications.

Modifying geopolymer wettability by plasma treatment and high-carbon fly ash

This paper deals with investigation of changes in geopolymer wettability with increasing mass fraction of high-carbon fly ash and surface treatment by cold atmospheric plasma (CAP) to determine the influence of fly ash on wettability and whether it is a viable method to increase surface wettability for further surface treatment. In this study, multiple samples of geopolymers were prepared, including those with 16% and 32% of high-carbon fly ash from coal-fired power station. Wettability of samples was then measured before and after plasma treatment, both on surface and cut surface by using static sessile drop method to measure the differences in contact angle. While addition of fly ash only had low effect on the wettability, as in most cases, it only lowered the initial contact angle without speeding up the speed of soaking for compact geopolymer and actually slowed the soaking for foamed geopolymer, plasma treatment had significant impact and made the geopolymer completely hydrophobic, making plasma treatment a viable method to increase geopolymer wettability.

A low power 50 Hz argon plasma for surface modification of polytetrafluoroethylene

The characteristics of a low power 50 Hz argon plasma for surface treatment of polytetrafluoroethylene (PTFE) film is presented in this article. The current–voltage behavior of the discharge and time-varying intensity of the discharge showed that a DC glow discharge was generated in reversed polarity at every half-cycle. At discharge power between 0.5 and 1 W, the measured electron temperature and density were 2–3 eV and ∼108 cm−3, respectively. The optical emission spectrum of the argon plasma showed presence of some ‘impurity species’ such as OH, N2 and H, which presumably originated from the residual air in the discharge chamber. On exposure of PTFE films to the argon glow plasma at pressure 120 Pa and discharge power 0.5 to 1 W, the water contact angle reduced by 4% to 20% from the original 114° at pristine condition, which confirms improvement of its surface wettability. The increase in wettability was attributed to incorporation of oxygen-containing functional groups on the treated surface and concomitant reduction in fluorine as revealed by the XPS analysis and increase in surface roughness analyzed from the atomic force micrographs. Ageing upon storage in ambient air showed retention of the induced increase in surface wettability.

Antibacterial activity, cytocompatibility, and thermomechanical stability of Ti40Zr10Cu36Pd14 bulk metallic glass.

This paper envisions Ti40Zr10Cu36Pd14 bulk metallic glass as an oral implant material and evaluates its antibacterial performance in the inhabitation of oral biofilm formation in comparison with the gold standard Ti–6Al–4V implant material. Metallic glasses are superior in terms of biocorrosion and have a reduced stress shielding effect compared with their crystalline counterparts. Dynamic mechanical and thermal expansion analyses on Ti40Zr10Cu36Pd14 show that these materials can be thermomechanically shaped into implants. Static water contact angle measurement on samples' surface shows an increased surface wettability on the Ti–6Al–4V surface after 48 ​h incubation in the water while the contact angle remains constant for Ti40Zr10Cu36Pd14. Further, high-resolution transmission and scanning transmission electron microscopy analysis have revealed that Ti40Zr10Cu36Pd14 interior is fully amorphous, while a 15 ​nm surface oxide is formed on its surface and assigned as copper oxide. Unlike titanium oxide formed on Ti–6Al–4V, copper oxide is hydrophobic, and its formation reduces surface wettability. Further surface analysis by X-ray photoelectron spectroscopy confirmed the presence of copper oxide on the surface. Metallic glasses cytocompatibility was first demonstrated towards human gingival fibroblasts, and then the antibacterial properties were verified towards the oral pathogen Aggregatibacter actinomycetemcomitans responsible for oral biofilm formation. After 24 ​h of direct infection, metallic glasses reported a >70% reduction of bacteria viability and the number of viable colonies was reduced by ∼8 times, as shown by the colony-forming unit count. Field emission scanning electron microscopy and fluorescent images confirmed the lower surface colonization of metallic glasses in comparison with controls. Finally, oral biofilm obtained from healthy volunteers was cultivated onto specimens' surface, and proteomics was applied to study the surface property impact on species composition within the oral plaque.

Graphitic Carbon Nitride Platforms Modified with Gold-Aryl Nanoparticles for Efficient Electrocatalytic Hydrogen Evolution

ABSTRACT Electrocatalytic hydrogen evolution reactions (HER) offer an enduring strategy for hydrogen fuel production and are vital for sustainable energy conversion and storage. To explore efficient and durable HER electrocatalysts, we fabricated gold-aryl nanoparticles (AuNPs-COOH) anchored on graphitic carbon nitride (g-C3N4) sheets by reducing aryldiazonium tetrachloroaurate(III) salt with sodium borohydride at room temperature in water. Two different nanocomposites, AuNPs-COOH-g-C3N4 (H) (higher amount of g-C3N4) and AuNPs-COOH-g-C3N4 (L) (lower amount of g-C3N4) were prepared. Contact angle measurements revealed that the increased surface wettability of the nanocomposites on glass and silicon wafer surfaces compared to pristine g-C3N4. Cyclic voltammetry, electrochemical impedance spectroscopy, double-layer capacitance, linear sweep voltammetry, and chronoamperometry measurements revealed that AuNPs-COOH-g-C3N4 (L) displayed the best HER performance in 0.1 M H2SO4 electrolyte. Overall, nanocomposites exhibited higher electrocatalytic activity compared to bare AuNPs-COOH and pristine g-C3N4 in current density and onset potential values. The AuNPs-COOH-g-C3N4 (L) nanocomposite offered an excellent electrocatalytic activity and displayed a current density of 53.4 mA/cm2 at 0.72 V vs RHE, which is nearly twice compared to bare AuNPs-COOH of 33.1 mA/cm2. In addition, the nanocomposite showed the lowest onset potential of 0.14 V vs RHE compared to 0.26 V and 0.31 V for AuNPs-COOH-g-C3N4 (H) and AuNPs-COOH, respectively.

Numerical simulation of two-phase flow in a multi-gas channel of a proton exchange membrane fuel cell

Understanding the two-phase distribution characteristics within the multi-gas channel of a fuel cell is important for improving fuel cell performance. In the paper, the volume of fluid model is used to predict the dynamic behaviour of water in the multi-gas channel, analyze the pressure drop, velocity distribution, and flow resistance coefficient between different channels, and investigate the influence of operating conditions, surface wettability and channel structure on the two-phase distribution characteristics in the channel. The results show that water undergoes the processes of growth, separation, single droplet transport, wall impact, droplet collision, liquid film formation, and liquid film transport in the multi-gas channel. Inlet velocity and surface wettability significantly affect the pressure drop, water saturation, and surface water coverage. As the inlet velocity and gas diffusion layer surface wettability increase, the flow resistance coefficient and unevenness of the distribution decrease, indicating that the in-channel flow distribution homogeneity is enhanced. The rectangular channel has better water removal and flow distribution uniformity than the tapered channel, and the unevenness of distribution decreases significantly with decreasing rectangular width, from 0.15715 to 0.00315. The research work is a guide to understanding water transport in multi-gas channels, accelerating water removal, and improving inter-channel flow distribution uniformity.

Experiments to understand bubble base evaporation mechanisms and heat transfer on nano-coated surfaces of varying wettability under nucleate pool boiling regime

Absolute surface wettability effects on the characteristics of nucleate pool boiling heat transfer under saturated conditions are investigated with water as working fluid. Wettability of the base surface (ITO-coated sapphire) is modified by coating 60 nm thick SiO2 film using different thin film deposition techniques. In this way, two surfaces with modified wettability (30 o and 65 o static contact angles) have the same surface chemistry with negligible variation in surface roughness, while the base surface itself acts as the third surface with 90 o static contact angle. Experiments are conducted for various constant heat flux conditions. Bubble dynamics and temperature distributions of the substrate surface are mapped in-situ using high speed videography and IR thermography, respectively. Pool boiling curves and overall heat transfer coefficient curves, obtained from the recorded IR images, showed that the overall boiling performance increases with enhanced surface wettability. The observed enhancement has been explained on the basis of the modified bubble dynamics and the associated bubble base evaporation mechanism. The bubble dynamics parameters such as bubble departure diameter and departure frequency, and nucleation site density (NSD) were found to get altered so as to augment the total evaporative heat flux with increasing surface wettability. The heat transfer coefficients and heat transfer rates corresponding to bubble base evaporation for isolated vapor bubble revealed that higher wettability surfaces outperform the surfaces with lower wettability in heat transport through bubble base evaporation. The corresponding underlying mechanisms have been identified. In addition, it was found that the microlayer evaporation mechanism is more efficient as compared to that based on pure contact line evaporation in transporting the heat away from the surface.

Enhancing the adhesive bonding strength of Ti6Al4V sheets with fiber laser texturing

In this study, Ti6Al4V sheet blocks with a thickness of 1 mm were joined in a single lap joint form using a two-component epoxy adhesive binder. In order to increase the bonding performance, the surfaces were prepared with sandpaper, acid etching, and laser texturing before the bonding process. Laser texturing was carried out with an average 20 W laser power with 25 kHz laser frequency and variable scanning speeds (1000, 750, 500 mm/s). The generated surfaces were examined with an optical microscope, and surface roughness values were measured. The wettability properties of the surfaces were examined by the sessile drop test method. It was observed that the laser texturing process increases surface wettability significantly. The strength of the adhesive joints was determined using a tensile test setup. Additionally, fracture surfaces were examined under a scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis was conducted. According to these results, it was observed that all surface preparation processes increased the adhesive bonding and shear lap joint bond strength. Especially, up to a 4.5 times increase was observed compared to the sample not treated with laser texturing.

Characterization and Optimization of a Conical Corona Reactor for Seed Treatment of Rapeseed

Plasma agriculture is a growing field that combines interdisciplinary areas with the aim of researching alternative solutions for increasing food production. In this field, plasma sources are used for the treatment of different agricultural goods in pre- and post-harvest. With the big variety of possible treatment targets, studied reactors must be carefully investigated and characterized for specific goals. Therefore, in the present study, a cone-shaped corona reactor working with argon was adapted for the treatment of small seeds, and its basic properties were investigated. The treatment of rapeseed using different voltage duty cycles led to an increase in surface wettability, possibly contributing to the accelerated germination (27% for 90% duty cycle). The discharge produced by the conical reactor was able to provide an environment abundant with reactive oxygen species that makes the process suitable for seeds treatment. However, operating in direct treatment configuration, large numbers of seeds placed in the reactor start impairing the discharge homogeneity.

Hydrophilic implants generated using a low-cost dielectric barrier discharge plasma device at the time of placement exhibit increased osseointegration in an animal pre-clinical study: An effect that is sex-dependent

ObjectivesIncreased wettability of titanium and titanium alloy surfaces due to processing and storage methods increases osteoprogenitor cell differentiation and osseointegration compared to microroughness alone. Implants that are exposed to air have a hydrophobic surface due to adsorption of atmospheric hydrocarbons, which can limit overall implant success. Dielectric barrier discharge plasma (DBD) is one method to increase surface hydrophilicity. Although current DBD methods yield a hydrophilic surface, adsorbed hydrocarbons rapidly restore hydrophobicity. We demonstrated that application of DBD to implants previously packaged in a vacuum, generates a hydrophilic surface that supports osteoblastic differentiation in vitro and this can be done immediately prior to use. In the present study, we tested the hypothesis that DBD treatment to alter surface wettability at the time of implant placement will improve osseointegration in vivo. Materials and methodsTwenty male and sixteen female rabbits were used in a preclinical trans-axial femur model of osseointegration. Control and DBD treatment implants were inserted randomized per hind limb in each rabbit (1 implant/hind-limb). At 6 weeks post-surgery, bone-to-implant contact, adjacent bone volume, and torque to failure were assessed by micro-CT, calcified histology, and mechanical testing. ResultsDBD plasma treatment of vacuum-sealed implants increased surface wettability and did not change surface chemistry or roughness. Peak torque and torsional energy, and bone-to-implant contact increased with DBD treatment in males. In contrast, female rabbits showed increased osseointegration equal to DBD treated male implants regardless of DBD plasma treatment. ConclusionDBD treatment is an effective method to enhance osseointegration by increasing surface wettability; however, this response is sex dependent. In healthy female patients, DBD treatment may not be necessary but in older patients or patients with compromised bone, this treatment could be an effective measure to ensure implant success.

Surface Charge Affecting Fluid–Fluid Displacement at Pore Scale

AbstractEfficiency in fluid–fluid displacement is drastically reduced by viscous fingering, limiting the overall effectiveness in enhanced oil recovery, membrane science, and lateral flow devices used in biomedical applications. Local instabilities at the fluid–fluid interface lead to finger‐like patterns when a less viscous fluid displaces an immiscible fluid of higher viscosity. This widely observed phenomenon in multiphase flow inside porous media is infamously intricate to control, especially for given geometry and viscosity ratio. The presented study uses a highly controlled microfluidic porous network structure with tailored ionic surface strength. The direct correlation of viscous fingering evolution on the porous structure's zeta potential at a pore‐scale level is demonstrated via polyelectrolyte coatings using a layer‐by‐layer technique. Displacement patterns are tuned from vigorous viscous fingering over stable displacement to corner flow events across a broad range of capillary numbers depending on the applied coatings. The experimental data show an increasing trend of oil recovery with increasing surface wettability, consistent with several previous findings. Furthermore, the results reveal that surface zeta potential correlates positively with recovery rate but negatively with the displacement stability quantified by the fractal dimension. These insights enable a more targeted porous media design to obtain optimal multiphase flow control.

Applying nano-HA in addition to scaling and root planing increases clinical attachment gain

PurposeThis study evaluated the efficacy of treating periodontitis using subgingival nano-hydroxyapatite powder with an air abrasion device (NHAPA) combined with scaling and root planing (SRP).MethodsA total of 28 patients with stage III periodontitis (grade B) were included in this study, although 1 was lost during follow-up and 3 used antibiotics. The patients were divided into a test group and a control group. All patients first received whole-mouth SRP using hand instruments, and a split-mouth approach was used for the second treatment. In the test group, the teeth were treated with NHAPA for 15 seconds at 70% power per pocket. Subgingival plaque samples were obtained from the 2 deepest pockets at the test and control sites before treatment (baseline) and 3 months after treatment. The full-mouth plaque index (PI), gingival index (GI), papillary bleeding index (PBI), bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL) were recorded at baseline and at 1- and 3-month post-treatment. Real-time polymerase chain reaction was used to determine the colonisation of Treponema denticola (Td), Porphyromonas gingivalis (Pg), and Aggregatibacter actinomycetemcomitans in the subgingival plaque.ResultsFrom baseline to the first month, the test group showed significantly larger changes in BOP and CAL (43.705%±27.495% and 1.160±0.747 mm, respectively) than the control group (36.311%±27.599% and 0.947±0.635 mm, respectively). Periodontal parameters had improved in both groups at 3 months. The reductions of PI, GI, BOP, PD, and CAL in the test group at 3 months were greater and statistically significant. The total bacterial count and Td and Pg species had decreased significantly by the third month in both groups (P<0.05).ConclusionsApplying NHAPA in addition to SRP improves clinical periodontal parameters more than SRP alone. Subgingival NHAPA may encourage clot adhesion to tooth surfaces by increasing surface wettability.

Molecular dynamics study of nanoscale droplets impacting on textured substrates of variable wettability

The impact of nanodroplets on a solid surface is widely encountered in industrial processes. Understanding the processes that occur when nanodroplets impact a rough surface is of great significance, but the mechanism and dynamics of these processes remain unclear due to the limitations of experimental tools and the shortcomings of most macroscale models. This paper describes molecular dynamics simulations conducted to explore these nanoscale processes. The wettability and solid fraction of the textured substrate and the effects of different impact velocities are investigated. We demonstrate that the maximum spreading time can be described as a power law of the Weber number and that the maximum spreading factor increases with increasing surface wettability. Owing to changes in the attraction between the nanodroplets and the textured substrate, the maximum spreading factor also increases as the solid fraction increases. Based on energy analysis, a theoretical model is proposed for predicting the maximum spreading factor, and this is found to be in good agreement with the simulation results. The results of this study provide useful guidance for predicting the dynamics of nanodroplet impacts.

Optimal nanocone geometry for water flow

AbstractThe pursuit, toward transport efficiency, is significantly necessary for energy conversion, water filtration. However, structure design, aiming at further enhancing nanoconfined water flow, is still lacking. With the motivation to bridge the knowledge gap, a simple yet practical model regarding the nanocone structure design is established. This research demonstrates that nanocone, with desirable opening angle and length, possesses the capacity to achieve the optimal flow behavior. Flow resistance occurring inside nanocones, and that at cone entrance, exit, are considered. Optimal nanocone geometry can be determined based on the minimization of total resistance. Results show that (a) suitable opening angle spans from 10° to 30° over a wide range of nanocone geometry; (b) evident decline tendency of the suitable opening angle toward the increasing surface wettability is captured; and (c) water transport capacity inside optimal nanocone is 4–50 times that within cylindrical nanopores. This article forms a theoretical framework for nanocone design.

Research of the replacement of dichromate with depressants mixture in the separation of copper-lead sulfides by flotation

• Humic substance and hydrogen peroxide are promising depressants on galena. • The hydrogen peroxide can accelerate dissolution of galena lattice. • An adsorption model is finally obtained. To reduce the environmental impact caused by highly toxic dichromate in flotation separation of copper-lead sulfide, the replacement of dichromate with depressants mixture (humic substance and hydrogen peroxide) was investigated in this paper. The single mineral flotation and the mixed binary minerals experiment at pH 6.5 showed that combined depressants could be efficient in separating galena from chalcopyrite and achieve a lead concentrate comparable to conventional method using dichromate as typical depressant. The contact angle measurement and atomic force microscopy (AFM) imaging indicated that, for the same concentration of sodium humate, the treatment by hydrogen peroxide could increase surface wettability and largely enhance chemical adsorption of humate on galena surface. Ion dissolution tests and adsorption tests indicated that the hydrogen peroxide can accelerate dissolution of galena lattice and the hydrogen peroxide or Pb 2+ could promote the adsorption of NaHA on the surface of galena.

Improved bond performances of self-etch adhesives to enamel through increased MDP–Ca salt formation via phosphoric acid pre-etching

ObjectivesThe chemical affinity between 10-methacryloyloxydecyl dihydrogen phosphate (MDP) and hydroxyapatite (HAp) is an important factor in the enamel bonding provided by MDP-based self-etch (SE) adhesives, besides microinterlocking mechanisms. This study aimed to investigate how phosphoric acid pre-etching affects MDP–Ca salt formation in the application of MDP-based SE adhesives. MethodsSingle Bond Universal (SBU), All Bond Universal (ABU), Clearfil Universal Bond Quick (CBQ), and a MDP-based all-in-one adhesive (EXP) were used in both SE and etch-and-rinse (ER) modes, along with Clearfil SE Bond and untreated enamel (UE) as controls. The MDP–Ca salts produced with or without etching were examined by nuclear magnetic resonance, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Zeta potential, contact angle, and scanning electron microscopy measurements were employed to elucidate the mechanism behind the changes in MDP/HAp chemical affinity upon pre-etching. ResultsThe percentage of MDP–Ca salt in EXP_ER (73.13%) was higher than that in EXP_SE (43.27%). Characteristic CH2 (1130, 1441, 2853, and 2909 cm−1), CC (1641 cm−1), and CO (1718 cm−1) bands were observed in the Raman spectra of EXP_ER. Pre-etching increased the negative zeta potential of the enamel surface compared to that of UE (P < 0.001). The contact angles of MDP-based adhesives applied to pre-etched enamel were significantly lower than those of the self-etched surface (P < 0.05). SignificanceThe increased MDP–Ca salt formation is a significant advantage of phosphoric acid pre-etching, improving the MDP/HAp chemical affinity in addition to increasing surface wettability.

High surface area nitrogen-functionalized Ni nanozymes for efficient peroxidase-like catalytic activity.

Nitrogen-functionalization is an effective means of improving the catalytic performances of nanozymes. In the present work, plasma-assisted nitrogen modification of nanocolumnar Ni GLAD films was performed using an ammonia plasma, resulting in an improvement in the peroxidase-like catalytic performance of the porous, nanostructured Ni films. The plasma-treated nanozymes were characterized by TEM, SEM, XRD, and XPS, revealing a nitrogen-rich surface composition. Increased surface wettability was observed after ammonia plasma treatment, and the resulting nitrogen-functionalized Ni GLAD films presented dramatically enhanced peroxidase-like catalytic activity. The optimal time for plasma treatment was determined to be 120 s; when used to catalyze the oxidation of the colorimetric substrate TMB in the presence of H2O2, Ni films subjected to 120 s of plasma treatment yielded a much higher maximum reaction velocity (3.7⊆10−8 M/s vs. 2.3⊆10−8 M/s) and lower Michaelis-Menten coefficient (0.17 mM vs. 0.23 mM) than pristine Ni films with the same morphology. Additionally, we demonstrate the application of the nanozyme in a gravity-driven, continuous catalytic reaction device. Such a controllable plasma treatment strategy may open a new door toward surface-functionalized nanozymes with improved catalytic performance and potential applications in flow-driven point-of-care devices.

Numerical investigation on the effects of non-gaussian random and regular textured rough surface on critical heat flux

Modified surfaces with rough structure have been widely employed to enhance the critical heat flux (CHF) in the heat transfer engineering. Since any structure diagram in its intersecting surface can be treated as spectrum/signal in 2D dimensions, and any spectrum in time domain and in frequency domain can be transformed into sine transforms by the Fourier. Thus, in this article, the effects of the non-gaussian random rough surface and the ordered sine function structured surface were investigated on the CHF enhancement using the fast Fourier transform (FFT) method and the hybrid thermal lattice Boltzmann method (LBM). It finds out that for the non-gaussian random rough surface, CHF is enhanced with decreasing the skewness of the surface. The enhancement seems limited with further reduced the skewness. Besides, the CHF enhancement will be improved by increasing surface wettability. For regular textured surfaces, increasing either the amplitude or the periodicity of the surface structures initially increases the CHF and then the enhancement is impeded with further increase. It concludes that there exists an optimal design of the surface morphology with either non-gaussian random structure or the ordered sine function structure for the CHF enhancement in pool boiling.

In vitro study on conditioned dental root surfaces: evaluation of wettability, smear layer, and blood clot adhesion.

The aim was to investigate the efficacy of citric acid and ethylenediaminetetraacetic acid (EDTA)-based treatments on smear layer removal and blood clot formation and stabilization. After scaling and root planing, 126 root samples were divided into seven groups treated with: deionized water; saline; citric acid solution; Ultradent Citric Acid gel; EDTA solution; EDTA-based PrefGel; or untreated. Each group was divided into three subgroups: I for the evaluation of smear layer removal and surface wettability, II and III for the evaluation of blood clot formation and stabilization in static or dynamic rinsing conditions. Conditioning agent treatments increased surface wettability with respect to untreated samples (Ultradent: 45 ± 1 degrees, P = 6.2 × 10-3; EDTA: 36 ± 5 degrees, P = 8.9 × 10-7; PrefGel: 47 ± 7 degrees, P = 3.2 × 10-2). Smear layer removal (30% to 60% with respect to untreated samples) was observed for all the conditioning agents. Clot was absent on untreated samples and samples treated with deionized water. Clot quality was significantly higher for samples treated with conditioning agents (P < .05) and similar between group II and III (P > .05). A statistically significant difference (P = .027) was observed for clot coverage of the saline group, comparing static and dynamic rinsing, confirming the positive effect of treatments on clot stabilization. The use of conditioning agents improves smear layer removal and clot formation and stabilization with respect to scaling and root planing procedure only, which is, however, considered an essential procedure to promote wound healing in periodontal surgery.