Wettability and adhesion of nanotubes applied to the surface of titanium implants by anodic oxidation.

The aim of this study was to evaluate the wettability and adhesion of self-organized TiO2 nanotubes formed on the surface of 8 commercially pure titanium (CP-Ti) disks and 12 dental implants (n = 12) by anodization in a glycerol-H2O (50-50 v/v) electrolyte containing NH4F. Two disk specimens were not submitted to anodization (controls). The nanotubes thus obtained had average dimensions of 50 nm in diameter by 900 nm in length. The treated disk specimens were stored for 2, 14 and 35 days (n = 2), and the wettability of their surfaces was evaluated with a goniometer at the end of each storing period. The adhesion of nanotubes to titanium was evaluated by field emission scanning electron microscopy after subjecting the 12 implants to a simulation of clinical stress in two-part synthetic bone blocks. After installing the implants with the application of an insertion torque, the two halves of the block were separated, and the implants were removed. The nanotubes remained adhered to the substrate, with no apparent deformation. The contact angles after 14 days and 35 days were 16.47° and 17.97°, respectively, values significantly higher than that observed at 2 days, which was 9.24° (p < 0.05). It was concluded that the method of anodic oxidation tested promoted the formation of a surface suitable for clinical use, containing nanotubes with levels of wettability and adhesion to titanium compatible with those obtained by other methods found in the literature. The wettability, however, did not prove stable over the tested storage periods.

Clinical and histological efficacy of a new implant surface in achieving early and stable osseointegration: An in vivo study.

An advantage of treated implant surfaces is their increased degree of hydrophilicity and wettability compared with untreated, machined, smooth surfaces that are hydrophobic. The present preclinical in vivo study aimed to compare the two implant surface types, namely SLActive (Straumann, Basel, Switzerland) and nanohydroxyapatite (Hiossen, Englewood Cliffs, NJ, USA), in achieving early osseointegration. The authors hypothesised that the nanohydroxyapatite surface is comparable to SLActive for early bone-implant contact. Six male mixed foxhounds underwent mandibular premolar and first molar extraction, and the sockets healed for 42 days. The mandibles were randomised to receive implants with either SLActive (control group) or nanohydroxyapatite surfaces (test group). A total of 36 implants were placed in 6 animals, and they were sacrificed at 2 weeks (2 animals), 4 weeks (2 animals) and 6 weeks (2 animals) after implant surgery. When radiographic analysis was performed, the difference in bone level between the two groups was statistically significant at 4 weeks (P = 0.024) and 6 weeks (P = 0.008), indicating that the crestal bone level was better maintained for the test group versus the control group. The bone-implant contact was also higher for the test group at 2 (P = 0.012) and 4 weeks (P = 0.011), indicating early osseointegration. In conclusion, this study underscored the potential of implants with nanohydroxyapatite surfaces to achieve early osseointegration.

The wettability of complete denture base materials constructed by conventional versus digital techniques: an in-vitro study.

BACKGROUND: Decreased salivary flow can make the patients uncomfortable with their complete dentures and affects the retention of the dentures. Milling and 3D printing have become an alternative to conventional denture construction techniques. The goal of this study was to evaluate the effect of conventional and digital techniques of the complete denture construction on the denture surface wettability with distilled water and saliva substitute before and after thermocycling. METHODS: A total of 30 specimens were utilized in the present study. Specimens were divided according to the construction techniques into 3 groups (n = 10 each). Group I: Heat-polymerized polymethylmethacrylate (PMMA) group, group II: Milled group, and group III: 3-dimensional (3D)-printed group. All the specimens were subjected to 2000 cycles of thermal aging in a thermocycler. The wettability of all specimens to water and saliva substitute was measured via a contact angle goniometer (Olympus TGHM, Rame-hart Inc, USA) before and after thermocycling. Descriptive statistical analysis, plots, and the Shapiro-Wilk test were used to verify normality for each variable. One-way ANOVA was used to compare the 3 study groups, while paired samples t-test was used to compare the differences within each group (P < .05). RESULTS: The smallest contact angle of drop of water to the denture base specimens before and after thermocycling were recorded in the milled group (53.0 ± 4.77 and 50.27 ± 2.30, respectively), followed by the heat polymerized PMMA group (85.65 ± 4.71 and 65.06 ± 2.27, respectively), and the 3D-printed group (91.34 ± 6.74 and 90.86 ± 8.57, respectively). While the smallest contact angle of drop of saliva substitute to denture base specimens was recorded in the milled group (56.82 ± 2.29 and 34.85 ± 7.51, respectively), followed by the 3D-printed group (72.87 ± 4.83 and 58.14 ± 9.58, respectively) and the heat polymerized PMMA group (83.62 ± 4.12 and 67.82 ± 4.93, respectively). There was statistically significant difference between the groups (P < .05). A significant decline in the average contact angle of drop of saliva has been reported in all groups after thermocycling. The contact angle values differed significantly between saliva substitute and distilled water in both 3D-printed and milled groups after thermocycling (P < .001). CONCLUSIONS: The milled denture base material presented the best wettability to water and saliva substitute than the 3D-printed and the heat-polymerized PMMA materials. Saliva substitutes improve the wetting ability of denture base materials manufactured by CAD/CAM compared with water.

Multifunctional composite film of curcumin Pickering emulsion stabilized by lignocellulose nanofibrils isolated from bamboo shoot shells for monitoring shrimp freshness.

Concerns about food safety and environmental impact from chemical surfactants have prompted interest in natural lignocellulosic materials as alternatives. In this study, we combined hydrated deep eutectic solvent (DES) pretreatment with ultrasound treatment to prepare lignocellulosic nanofibrils (LCNF) from bamboo shoot shells with appropriate surface properties for stabilizing Pickering emulsions. The pretreatment intensity effectively modulated the surface characteristics of LCNF, achieving desirable wettability through lignin retention and in-situ esterification. The resulting LCNF/curcumin Pickering emulsion (CPE) demonstrated curcumin protection and pH-responsive color changes, while the ensuing CPE/PVA composite film exhibited ultraviolet shielding, mechanical strength, oxygen barrier, and antioxidant properties. Furthermore, the CPE/PVA film showed promise as a real-time indicator for monitoring shrimp freshness, maintaining sensitivity to spoilage even after six months of storage. These findings advance the advancement of green LCNF technologies, providing eco-friendly solutions for valorizing bamboo shoot shells and enhancing the application of LCNF in Pickering emulsions.

Quantification of immiscible displacement in a rough-walled fracture through direct visualization.

Subsurface substance migration in the fractured rock aquifer is mainly controlled by fractures, and immiscible fluid-fluid displacement in fractures is important to many geophysical processes and engineering activities. Using a fracture-visualization system, we present the qualitative and quantitative assessment of fracture geometry associated with fluid movement and distribution in the rough fracture. Based on fracture geometry and statistical analysis, we first conducted a quantitative study of fracture surface roughness and aperture distribution. Then, fractal dimensions of displacement front and residual oil distribution were determined by image processing procedures. Influenced by wettability and micro-scale roughness, at the end of the displacement, residual oil saturation of molded sample is lower (6.45%-25.74%), and displacement pattern is more uniform, indicating that displacement effect is better. Due to smaller differences in residual oil saturation (9.08%) under different injection directions, the impact of wettability on the displacement process is greater than that of anisotropic roughness. Additionally, the fractal dimension of the displacement front increased under low injection rates initially but decreased when the rate was increased later. Overall, visualized temporal monitoring of experimental images enabled us to provide a preliminary assessment of the impact of anisotropic roughness and the material constituting the fracture wall on invading fluid saturation and the fractal dimension of the displacement front under various injection rates.

A crystal engineering approach for rational design of curcumin crystals for Pickering stabilization of emulsions.

Emulsions stabilized via Pickering particles are becoming more and more popular due to their high stability and biocompatibility. Hence, developing new ways to produce effective Pickering particles is essential. In this work, we present a crystal engineering approach to obtain precise control over particle properties such as size, shape, and crystal structure, which may affect wettability and surface chemistry. A highly reproducible synthesis method via anti-solvent crystallization was developed to produce sub-micron sized curcumin crystals of the metastable form III, to be used as Pickering stabilizers. The produced crystals presented a clear hydrophobic nature, which was demonstrated by their preference to stabilize water-in-oil (W/O) emulsions. A comprehensive experimental and computational characterization of curcumin crystals was performed to rationalize their hydrophobic nature. Analytical techniques including Raman spectroscopy, powder X-ray diffraction (PXRD), Solid-State Nuclear Magnetic Resonance (SSNMR), scanning electron microscopy (SEM), Differential Scanning Calorimetry (DSC), confocal fluorescence microscopy and contact angle measurements were used to characterize curcumin particles in terms of shape, size and interfacial activity. The attachment energy model was instead applied to study relevant surface features of curcumin crystals, such as topology and facet-specific surface chemistry. This work contributes to the understanding of the effect of crystal properties on the mechanism of Pickering stabilization, and paves the way for the formulation of innovative products in fields ranging from pharmaceuticals to food science.

Properties of biodegradable polymer coatings with hydroxyapatite on a titanium alloy substrate.

Purpose: Titanium alloys are among the most widely used materials in medicine, especially in orthopedics. However, their use requires the application of an appropriate surface modification method to improve their properties. Such methods include anodic oxidation and the application of polymer coatings, which limit the release of alloying element ions. In addition, biodegradable polymer coatings can serve as a carrier for drugs and other substances. The paper presents the results of research on the physical properties of biodegradable polymer coatings containing nanoparticle hydroxyapatite on a titanium alloy substrate. Methods: A PLGA coating was used in the tests. The coatings on the substrate of the anodized Ti6Al7Nb alloy were applied by ultrasonic spray coating. The tests were carried out for coatings with various hydroxyapatite content (5, 10, 15, 20%) and thickness resulting from the number of layers applied (5, 10, 15 layers). The scope of the research included microscopic observations using scanning electron microscopy, topography tests with optical profilometry, structural studies using X-ray diffraction, as well as wettability and adhesion tests. Results: The results shows that with the use of ultrasonic spray coating system is possible to obtain the continuous coatings containing hydroxyapaptite. Conclusions: The properties of the coating can be controlled by changing the percentage of hydroxyapatite and the number of layers of which the coating is composed.

Efficient oil spill cleanup from water: Investigating the effectiveness of a sustainable anti-swelling hydrogel for rapid water repellency and oil absorption.

Considering the significant harm caused to aquatic ecosystems and marine life by oil spills and the discharge of oily wastewater, there is a pressing need to address this issue to protect our environment and prevent the wastage of valuable resources. We introduced a two-step approach to create an anti-swelling, water-repellent sorbent using a green polysaccharide called gum gellan, functionalized with Octadecyl trichlorosilane (OTS) through dip coating method. Natural gums like gellan have high absorption capability due to their large surface area. However, they are hydrophilic, which means they can only absorb water. This property makes them unsuitable for oil spill applications. To make gum gellan suitable for oil spill applications, we have modified it in this study. We have introduced a material called octadecyltrichlorosilane, which has low surface energy and hierarchical roughness. This modification changes the wettability of gellan from hydrophilic to hydrophobic/oleophilic, allowing it to absorb oil and repel water. The sorbent is analyzed using several techniques, such as FTIR, XRD, TGA, FE-SEM, BET, Raman, EDX, and H1-NMR. The hydrophobic sorbent obtained demonstrates low density, high surface area, and high porosity. These characteristics give it excellent floatability and immediate and exceptional selectivity for absorbing oil from water. Additionally, it does not absorb any detectable amount of water. The sorbent exhibited a water contact angle (WCA) of 140 ± 3 ° and an oil contact angle (OCA) of 0° for various oils and organic solvents. It has rapid oil absorption capacity of 3.72 g/g for diesel, and can be easily recovered after use. The BET analysis revealed that after the modification with OTS, the sorbent's total surface area increased from 0.579 m2/g to 4.713 m2/g. This indicates that the OTS modification greatly enhances the surface area and pore volume of the, thus improving its ability to absorb oil. This sorbent efficiently separates oil-in-water emulsions, both surfactant-stabilized and surfactant-free, achieving over 90% separation through gravity alone. Moreover, the sorbent can sustain its wettability even under harsh environmental conditions, including exposure to acids, alkalis, and salts. The absorption data predominantly aligned with the pseudo-2nd-order model. Thus, this sorbent provides a cost-effective alternative for efficiently absorbing and separating oil-water emulsions in households and industries.

Nanocellulose-short peptide self-assembly for improved mechanical strength and barrier performance.

Cellulose nanofibers (CNF) are the most abundant renewable nanoscale fibers on Earth, and their use in the design of hybrid materials is ever more acclaimed, although it has been mostly limited, to date, to CNF derivatives obtained via covalent functionalization. Herein, we propose a noncovalent approach employing a set of short peptides - DFNKF, DF(I)NKF, and DF(F5)NKF - as supramolecular additives to engineer hybrid hydrogels and films based on unfunctionalized CNF. Even at minimal concentrations (from 0.1% to 0.01% w/w), these peptides demonstrate a remarkable ability to enhance CNF rheological properties, increasing both dynamic moduli by more than an order of magnitude. Upon vacuum filtration of the hydrogels, we obtained CNF-peptide films with tailored hydrophobicity and surface wettability, modulated according to the peptide content and halogen type. Notably, the presence of fluorine in the CNF-DF(F5)NKF film, despite being minimal, strongly enhances CNF water vapor barrier properties and reduces the film water uptake. Overall, this approach offers a modular, straightforward method to create fully bio-based CNF-peptide materials, where the inclusion of DFNKF derivatives allows for facile functionalization and material property modulation, opening their potential use in the design of packaging solutions and biomedical devices.

Effects of UV Postcuring Times on the Color Stability, Surface Properties and Conversion of 3D-printed Temporary Resin Composites.

OBJECTIVE: To evaluate the effects of UV postcuring times on color stability (CS), surface properties (wettability [°] and surface roughness [Ra]), and conversion of 3D-printed resins for temporary restorations. METHODS: Disc-shaped specimens (10.0×3.0 mm) and maxillary central incisors (8.2×10.3 mm) were fabricated using provisional 3D-printed resin (PriZma Bio Prov [PZ] and PrintaX AA TEMP [PX]) in A2 shade and subjected to UV postcure times of 0 (T0), 5 (T1), 10 (T2), and 15 (T3) minutes (n=15). The incisors were used for CS evaluation with a colorimeter. In contrast, discs were used to measure the contact angle using the sessile drop method, surface roughness with an optical profilometer, and degree of conversion with FT-NIR. For CS, Ra, contact angle, and degree of conversion, a two-way ANOVA with Bonferroni post-hoc test (α=0.05) was used. RESULTS: PX resin demonstrated greater color stability than PZ (p=0.001). Long UV postcuring times (10 to 15 minutes) will increase the contact angle (p=0.013) and stabilize the degree of conversion (p=0.01), while 5 to 10 minutes of UV postcuring will provide better surface smoothness (p=0.04) of both resins. CONCLUSIONS: Long UV postcuring times (10 to 15 minutes) lead to greater alterations in color, contact angle, and stability of the degree of conversion, while 5 to 10 minutes lead to a smoother surface of the 3D-printed temporary resins.

Desmodium intortum (Mill.) Urb. Protein Isolate Aggregates as Pickering Stabilizers: Physicochemical Characteristics and Emulsifying Properties.

This work aimed to investigate the feasibility of fabricating Pickering emulsions stabilized by Desmodium intortum protein isolate (DIPI) aggregates. The DIPI aggregates were formed using heat treatment, and the effects of ionic strength and pH on their properties were investigated. The heat-treated protein exposes its hydrophobic groups due to structural damage, resulting in rapid aggregation of the protein into aggregates with a size of 236 nm. The results showed that the aggregates induced by ionic strength had larger particle size and higher surface hydrophobicity and partial wettability. Moreover, this study explored effective strategies for bolstering Pickering emulsion stability through optimized DIPI aggregate concentration (c) and oil fraction (ø). The DIPI Pickering emulsion (DIPIPE) formed at c = 5% and ø = 0.7 was still highly stable after 30 days of storage. As confirmed by laser confocal microscopy, DIPI aggregates could be adsorbed onto the oil-water interface to form a network structure that could trap oil droplets in the network. Collectively, the Pickering emulsion stabilized by DIPI aggregates exhibited excellent stability, which not only deeply utilizes the low-value protein resources in the Desmodium intortum for the first time, but also demonstrates the potential of DIPI for the bio-based field.

Bioinspired colloidal crystal hydrogel pressure sensors with Janus wettability for uterus cervical canal tension perception.

The pursuit of flexible, sensitive, and cost-effective pressure sensors plays a pivotal role in medical diagnostics, particularly in the domain of cervical health monitoring. However, significant challenges remain in the economical production of flexible piezoresistive materials and the integration of microstructures aimed at enhancing sensor sensitivity. This urge highlights the use of innovative, stable hydrogel films that demonstrate robust adherence to soft biological tissues, thereby enabling prolonged bio-signal monitoring. In this study, we introduce an innovative integration of a flexible pressure electrical signal sensor with structural color hydrogel scaffolds. This integration leverages the tunability of the inverse opal structure to fine-tune the scaffold's adherence to the endocervical wall under varying environmental conditions and to amplify the sensitivity of pressure measurements. Our findings indicate that this novel approach holds promise for substantial enhancements in the manufacturing and functional capabilities of cervical pressure sensors, potentially revolutionizing personalized medical treatments and improving patient monitoring.

Functionalized flattened bamboo board: In-situ immersion assembly of flame-retardant, waterproof and anti-mold composite coatings.

The flattened bamboo board (FB) represents a promising innovation in the bamboo industry. To address the challenges of flammability and hygroscopicity, composite coatings consisting of melamine (MEL), phytic acid (PA), cerium ions (Ce3+), and sodium laurate (La) are assembled on the FB surface through an in-situ impregnation strategy. The resulting MEL/PA-Ce3+@La FB exhibits exceptional flame retardancy. It achieves a V-0 rating in the vertical burning test (UL-94) and boasts a high limiting oxygen index (LOI) value of 38.5 %. The coated FB exhibits superhydrophobicity, evidenced by a water contact angle of 156.5°, which can be attributed to the in-situ growth of PA-Ce3+ complexes (for constructing micro/nanoscale coarse structures) and the modification with La (for reducing surface energy).This superhydrophobic surface imparts both self-cleaning and anti-mold properties to the coated FB. Moreover, the coated FB exhibits excellent mechanical stability, withstanding 36 cycles of sandpaper abrasion and tape peeling without losing its hydrophobicity. In summary, this work provides an innovative strategy for the bamboo processing industry to produce flattened bamboo boards with combined flame retardancy, superhydrophobic and anti-mold properties. Such versatility holds significant potential to facilitate the utilization of flattened bamboo boards in the construction and decorative materials industries.

Surface energy-induced anti-wetting and anti-fouling enhancement of Janus membrane for membrane distillation.

Membrane distillation (MD) presents a promising alternative to conventional desalination systems, particularly for the treatment of hypersaline wastewater. However, the large-scale application of MD is hindered by challenges such as membrane wetting, membrane fouling, and low permeate flux. Herein, we proposed an air/liquid interface deposition method to fabricate a Janus membrane, termed the PVDF-PDA/PEI-Si membrane. The membrane featured a nanosieving, superhydrophilic polydopamine/polyethylenimine (PDA/PEI) layer decorated with silica nanoparticles, coupled with a microporous, hydrophobic polyvinylidene fluoride (PVDF) layer. The introduction of a dense PDA/PEI-Si layer featuring high surface energy significantly enhanced the wetting and fouling resistance of the membrane, with a minor effect on the permeate flux. The performance enhancement was particularly evident when hypersaline water containing sodium dodecyl sulfate (SDS) and oily contaminants was used as the feed. The interactions between the membrane and contaminants were calculated using the XDLVO theory and molecular dynamics simulations to elucidate the mechanisms underlying the enhanced anti-wetting and anti-fouling properties, respectively. According to the XDLVO theory, a large energy barrier must be overcome for the SDS to attach onto the PDA/PEI-Si surface. Meanwhile, molecular dynamics simulations confirmed the weak interaction energy between the oily foulants and the PVDF-PDA/PEI-Si membrane due to its high surface energy. This study presents a promising approach for the fabrication of high-performance MD membranes and provides new insights into the mechanisms underlying the enhanced anti-wetting and anti-fouling properties.

Transparent bamboo as a replacement for glass: Effects of lignin decolorisation methods on weatherability.

Transparent bamboo proved to be a promising substitute for glass due to its high light transmittance and excellent mechanical properties. Nevertheless, it was susceptible to outdoor weathering, which negatively affected its physical and mechanical properties. In this study, two decolorisation methods, namely the delignification method and the lignin modification method, were used to produce transparent bamboos with epoxy resin, referred to as DL-TB and LM-TB, respectively. The changes in surface color, optical and mechanical properties, wettability, thermal stability, and thermal insulation properties of transparent bamboo during accelerated UV weathering were evaluated. Additionally, the deterioration mechanism of DL-TB and LM-TB was investigated. The findings revealed that DL-TB demonstrated better transparency and mechanical properties than LM-TB, although it exhibited lower thermal insulation properties. Furthermore, DL-TB demonstrated enhanced color stability and higher hydrophobicity on weathered surfaces than LM-TB. Unexpectedly, the tensile properties of both two transparent bamboos significantly improved after weathering, especially for LM-TB, which was due to the EP post-curing and the formation of more hydrogen bonds between lignin and EP. These observations revealed that lignin played a key role in the photodegradation process of transparent bamboo, but further attempts should be made in future studies to improve its color stability.

Improved photostability, solubility, hygroscopic stability and antimicrobial activity of fleroxacin by synthesis of fleroxacin-D-tartaric acid pharmaceutical salt.

To improve the solubility of the fluoroquinolone drug fleroxacin (FL), based on the previous experience of our research group in synthesizing co-crystals/salts of quinolone drugs to improve the physicochemical properties of drugs, Fleroxacin-D-tartaric acid dihydrate salt (FL-D-TT, C17H19F3N3O3·C4H5O6·2(H2O)), was synthesized for the first time using fleroxacin and D/L-tartaric acid (D/L-TT). Structural characterization of FL-D-TT was carried out using single-crystal X-ray diffraction, infrared spectral analysis (FT-IR) and powder X-ray diffraction (PXRD). Molecular electrostatic potential analysis showed that D-tartaric acid interacted more readily with FL than L-tartaric acid. The solubility of FL-D-TT (9.71 mg/mL, 1.82 mg/mL) was significantly higher compared to FL (0.39 mg/mL, 0.71 mg/mL) in water and buffer solution at pH 7.4. This may be attributed to the formation of charge-assisted hydrogen bonds (CAHBs) between FL and D-TT that facilitates the dissociation of FL cations in the dissolution medium, leading to an increase in FL solubility. This also led to some improvement in the in vitro antimicrobial activity of FL-D-TT against E. coli, S. typhi, and S. aureus. In addition, the hygroscopic stability of FL has been improved. Surprisingly, FL-D-TT had better photostability than FL, which could be attributed to the introduction of D-TT to make the photosensitizing moiety of FL more stable, which led to the improvement of the photostability of FL.

A two-stage mechanistic reduced-order model of pharmaceutical tablet dissolution: Population balance modeling and tablet wetting functions.

We propose a two-stage reduced-order model (ROM) of pharmaceutical tablet dissolution that is comprised of (i) a mechanistic dissolution function of the active pharmaceutical ingredient (API) and (ii) a tablet wetting function. The former is derived from a population balance model, using a high-resolution finite volume algorithm for a given API crystal size distribution and dissolution rate coefficient. The latter is obtained from the mechanistic understanding of water penetration inside a porous tablet, and it estimates the rate at which the API is exposed to the buffer solution for a given formulation and the dimensions of the tablet, contact angle, and surface tension between the solid and liquid phases, liquid viscosity, and mean effective capillary radius of the pore solid structure. In turn, the two-stage model is mechanistic in nature and one-way coupled by means of convolution in time to capture the start time of the API dissolution process as water uptake, swelling, and disintegration take place. The two-stage model correlates dissolution profiles with critical process parameters (CPPs), critical material attributes (CMAs), and other crucial critical quality attributes (CQAs). We demonstrate the model's versatility and effectiveness in predicting the dissolution profiles of diverse pharmaceutical formulations. Specifically, we formulate and fabricate acetaminophen and lomustine solid tablets using different API content and size distributions, characterize their dissolution behavior, and estimate capillary radius as a function of tablet porosity. The estimations generated by the proposed models consistently match the experimental data across all cases investigated in this study.

Release of contraction stress of dental resin composites by water sorption.

Polymerization shrinkage of bonded resin composite restorations will result in the development of curing contraction stresses during setting and can cause debonding of the restoration or failure of the surrounding tooth structure. However, the hygroscopic expansion that occurs after exposure of the restorative to the wet oral environment can compensate for this shrinkage. OBJECTIVES: The purpose of this study was to determine the hygroscopic expansion of six commercial resin composites and relate it to their composition, mechanical properties, shrinkage, and contraction stress development. METHODS: Short-term volumetric shrinkage and contraction stress of the different composites were measured by mercury dilatometry and a universal testing machine. The long-term contraction stress was measured by the deflection of a bilayer strip of metal and a resin composite, which were stored dry as well as wet to determine the effect of hygroscopic expansion. The curvature of the strip was measured by profilometry over a period of 3 months. RESULTS: The curvature of the strip correlated well (r2 =0.74) with the initial contraction stress, showing that the contraction stress is an important factor in initial deformation. The water sorption in all specimens showed that the initial deformation, within 2-4 weeks after curing, was completely counteracted. A high correlation (r2 =0.90) between deflection and relative water sorption was found, where the relative water sorption is defined as the absolute water sorption corrected for the inorganic filler volume of the composite. SIGNIFICANCE: Within a period of 2-4 weeks after curing most of the curing contraction stresses of resin composite restoratives will be released by hygroscopic expansion.

Investigation and Analysis of Wettability, Anisotropy, and Adhesion in Bionic Upper and Lower Surfaces Inspired by Indocalamus Leaves.

Nature provides us with a wealth of inspiration for the design of bionic functional surfaces. Numerous types of plant leaves with exceptional wettability, anisotropy, and adhesion are extensively employed in many engineering applications. Inspired by the wettability, anisotropy, and adhesion of indocalamus leaves, bionic upper and lower surfaces (BUSs and BLSs) of the indocalamus leaf were successfully prepared using a facile approach combining laser scanning and chemical modification. The results demonstrated the BUSs and BLSs obtained similar structural features to the upper and lower surfaces of the indocalamus leaf and exhibited enhanced and more-controllable wettability, anisotropy, and adhesion. More importantly, we conducted a detailed comparative analysis of the wettability, anisotropy, and adhesion between BUSs and BLSs. Finally, BUSs and BLSs were also explored for the corresponding potential applications, including self-cleaning, liquid manipulation, and fog collection, thereby broadening their practical utility. We believe that this study can contribute to the enrichment of the research on novel biological models and provide significant insights into the development of multifunctional bionic surfaces.

Enhancing Swimming Performance of Magnetic Helical Microswimmers by Surface Microstructure.

Artificial bacterial flagella (ABF), also known as a magnetic helical microswimmer, has demonstrated enormous potential in various future biomedical applications (e.g., targeted drug delivery and minimally invasive surgery). Nevertheless, when used for in vivo/in vitro treatment applications, it is essential to achieve the high motion efficiency of the microswimmers for rapid therapy. In this paper, inspired by microorganisms, the surface microstructure was introduced into ABFs to investigate its effect on the swimming behavior. It was confirmed that compared with smooth counterparts, the ABF with surface microstructure reveals a smaller forward velocity below the step-out frequency (i.e., the frequency corresponding to the maximum velocity) but a larger maximum forward velocity and higher step-out frequency. A hydrodynamic model of microstructured ABF is employed to reveal the underlying movement mechanism, demonstrating that the interfacial slippage and the interaction between the fluid and the microstructure are essential to the swimming behavior. Furthermore, the effect of surface wettability and solid fraction of microstructure on the swimming performance of ABFs was investigated experimentally and analytically, which further reveals the influence of surface microstructure on the movement mechanism. The results present an effective approach for designing fast microrobots for in vivo/in vitro biomedical applications.