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Journal of Dental Research Apr 2019Novel silica-based infiltrations on the surface of zirconia have the potential to improve their bondability, allowing for the etching/silane adhesive bonding technique....
Novel silica-based infiltrations on the surface of zirconia have the potential to improve their bondability, allowing for the etching/silane adhesive bonding technique. Nonetheless, adhesively bonded joints are subject to mixed tensile and shear stresses when the restoration is in occlusal service. Thus, we aimed to investigate the effect of 2 novel silica-based infiltrations on the interfacial toughness of adhesively bonded zirconia using the Brazil nut method, which allows for controlled types of stresses to be applied at the interfaces. In total, 150 3Y-TZP (In-Ceram YZ; Vita) Brazil nuts were machined and randomly assigned to 3 groups: C, control (air abraded); SG, sol-gel silica infiltration; and GI, glass infiltration. SG specimens were immersed twice in silicic acid for 20 min and dried (100°C, 1 h). GI specimens were presintered (1,400°C, 1 h) before a glass powder slurry was applied to the intaglio surface. All specimens were then sintered (1,530°C, 2 h). Following adhesive bonding (Panavia F 2.0, Kuraray) and water storage (37°C) for 10 d, the Brazil nuts were subdivided into groups baseline and aged (40,000 thermal cycles between 5°C and 55°C, with a dwell time of 30 s). The Brazil nuts were subjected to axial-loading tests using various inclinations (precrack angle with load direction): Θ = 0°, 5°, 10°, 15°, or 25°, which define the stress type at the interface, from pure tension (0°) to increasing levels of shear. Under pure tension (0°), GI yielded superior interfacial fracture energy, SG and C were similar, and aging had no effect. Under predominantly shear stresses (25°), aging significantly decreased interfacial fracture energy of C and SG, while GI remained stable and was superior. The glass infiltration of the zirconia intaglio surface increases its adhesive bonding interfacial toughness. The sol-gel silica infiltration method requires improvement to obtain a homogeneous surface infiltration and an enhanced bond strength.
Topics: Aluminum Oxide; Ceramics; Dental Bonding; Materials Testing; Resin Cements; Resins, Synthetic; Silicon Dioxide; Stress, Mechanical; Surface Properties; Zirconium
PubMed: 30763138
DOI: 10.1177/0022034518819477 -
International Journal of Molecular... Apr 2017In recent years, zirconia has been a recognized implant material in clinical dentistry. In the present study, we investigated the performance of an alkali-modified...
In recent years, zirconia has been a recognized implant material in clinical dentistry. In the present study, we investigated the performance of an alkali-modified ceria-stabilized tetragonal ZrO₂ polycrystalline ceramic-based nanostructured zirconia/alumina composite (NANOZR) implant by assessing surface morphology and composition, wettability, bovine serum albumin adsorption rate, rat bone marrow (RBM) cell attachment, and capacity for inducing bone differentiation. NANOZR surfaces without and with alkali treatment served as the control and test groups, respectively. RBM cells were seeded in a microplate with the implant and cultured in osteogenic differentiation medium, and their differentiation was evaluated by measuring alkaline phosphatase (ALP) activity, osteocalcin (OCN) production, calcium deposition, and osteogenic gene expression. The alkali-treated NANOZR surface increased ALP activity, OCN production, calcium deposition, and osteogenesis-related gene expression in attached RBM cells. These data suggest that alkali treatment enhances the osteogenesis-inducing capacity of NANOZR implants and may therefore improve their biointegration into alveolar bone.
Topics: Aluminum Oxide; Animals; Bone Marrow Cells; Cell Differentiation; Cell Proliferation; Cells, Cultured; Dental Implants; Dental Materials; Nanoparticles; Osteogenesis; Rats; Surface Properties; Wettability; Zirconium
PubMed: 28383491
DOI: 10.3390/ijms18040780 -
Molecules (Basel, Switzerland) Feb 2016Optical absorption measurements are combined with electronic structure calculations to explore photochemistry of an α-Al₂O₃-PETN interface formed by a nitroester...
Optical absorption measurements are combined with electronic structure calculations to explore photochemistry of an α-Al₂O₃-PETN interface formed by a nitroester (pentaerythritol tetranitrate, PETN, C₅H₈N₄O12) and a wide band gap aluminum oxide (α-Al₂O₃) substrate. The first principles modeling is used to deconstruct and interpret the α-Al₂O₃-PETN absorption spectrum that has distinct peaks attributed to surface F⁰-centers and surface-PETN transitions. We predict the low energy α-Al₂O₃ F⁰-center-PETN transition, producing the excited triplet state, and α-Al₂O₃ F⁰-center-PETN charge transfer, generating the PETN anion radical. This implies that irradiation by commonly used lasers can easily initiate photodecomposition of both excited and charged PETN at the interface. The feasible mechanism of the photodecomposition is proposed.
Topics: Aluminum Oxide; Models, Molecular; Pentaerythritol Tetranitrate; Photochemical Processes; Photochemistry
PubMed: 26938517
DOI: 10.3390/molecules21030289 -
International Journal of Molecular... Jul 2023The dental prophylactic cleaning of a damaged resin-based composite (RBC) restoration with sodium bicarbonate can change the surface characteristics and influence the...
The dental prophylactic cleaning of a damaged resin-based composite (RBC) restoration with sodium bicarbonate can change the surface characteristics and influence the repair bond strength. The purpose of this study was to compare the effect of sodium bicarbonate (SB) and aluminum oxide (AO) surface treatments on the microtensile bond strength (µTBS) of repaired, aged RBC. Bar specimens were prepared from microhybrid RBC and aged in deionized water for 8 weeks. Different surface treatments (AO air-abrasion; SB air-polishing), as well as cleaning (phosphoric acid, PA; ethylene-diamine-tetraacetic-acid, EDTA) and adhesive applications (single bottle etch-and-rinse, ER; universal adhesive, UA), were used prior to the application of the repair RBC. Not aged and aged but not surface treated RBCs were used as positive and negative controls, respectively. The repaired blocks were cut into sticks using a precision grinding machine. The specimens were tested for tensile fracture and the µTBS values were calculated. Surface characteristics were assessed using scanning electron microscopy. AO-PA-UA (62.6 MPa) showed a 20% increase in µTBS compared to the NC (50.2 MPa), which proved to be the most significant. This was followed by SB-EDTA-UA (58.9 MPa) with an increase of 15%. In addition to AO-PA-UA, SB-EDTA-UA could also be a viable alternative in the RBC repair protocol.
Topics: Composite Resins; Aluminum Oxide; Sodium Bicarbonate; Edetic Acid; Surface Properties; Microscopy, Electron, Scanning; Dental Materials; Dental Bonding; Tensile Strength; Materials Testing; Resin Cements
PubMed: 37511327
DOI: 10.3390/ijms241411568 -
International Journal of Molecular... Aug 2021Efficient and safe nanopesticides play an important role in pest control due to enhancing target efficiency and reducing undesirable side effects, which has become a hot...
Efficient and safe nanopesticides play an important role in pest control due to enhancing target efficiency and reducing undesirable side effects, which has become a hot spot in pesticide formulation research. However, the preparation methods of nanopesticides are facing critical challenges including low productivity, uneven particle size and batch differences. Here, we successfully developed a novel, versatile and tunable strategy for preparing buprofezin nanoparticles with tunable size via anodic aluminum oxide (AAO) template-assisted method, which exhibited better reproducibility and homogeneity comparing with the traditional method. The storage stability of nanoparticles at different temperatures was evaluated, and the release properties were also determined to evaluate the performance of nanoparticles. Moreover, the present method is further demonstrated to be easily applicable for insoluble drugs and be extended for the study of the physicochemical properties of drug particles with different sizes.
Topics: Aluminum Oxide; Coated Materials, Biocompatible; Electrodes; Insecticides; Materials Testing; Metal Nanoparticles; Porosity; Surface Properties; Thiadiazines
PubMed: 34361113
DOI: 10.3390/ijms22158348 -
Proceedings of the National Academy of... Sep 2015Hierarchically designed structures with architectural features that span across multiple length scales are found in numerous hard biomaterials, like bone, wood, and...
Hierarchically designed structures with architectural features that span across multiple length scales are found in numerous hard biomaterials, like bone, wood, and glass sponge skeletons, as well as manmade structures, like the Eiffel Tower. It has been hypothesized that their mechanical robustness and damage tolerance stem from sophisticated ordering within the constituents, but the specific role of hierarchy remains to be fully described and understood. We apply the principles of hierarchical design to create structural metamaterials from three material systems: (i) polymer, (ii) hollow ceramic, and (iii) ceramic-polymer composites that are patterned into self-similar unit cells in a fractal-like geometry. In situ nanomechanical experiments revealed (i) a nearly theoretical scaling of structural strength and stiffness with relative density, which outperforms existing nonhierarchical nanolattices; (ii) recoverability, with hollow alumina samples recovering up to 98% of their original height after compression to ≥ 50% strain; (iii) suppression of brittle failure and structural instabilities in hollow ceramic hierarchical nanolattices; and (iv) a range of deformation mechanisms that can be tuned by changing the slenderness ratios of the beams. Additional levels of hierarchy beyond a second order did not increase the strength or stiffness, which suggests the existence of an optimal degree of hierarchy to amplify resilience. We developed a computational model that captures local stress distributions within the nanolattices under compression and explains some of the underlying deformation mechanisms as well as validates the measured effective stiffness to be interpreted as a metamaterial property.
Topics: Algorithms; Aluminum Oxide; Ceramics; Compressive Strength; Computer Simulation; Computer-Aided Design; Fractals; Hardness; Materials Testing; Nanostructures; Nanotechnology; Polymers; Stress, Mechanical; Tensile Strength
PubMed: 26330605
DOI: 10.1073/pnas.1509120112 -
International Journal of Molecular... May 2023Industrial wastewater is the main source of an excessive amount of molybdenum (Mo) in natural ecosystems. It is necessary to remove Mo from wastewater before it is...
Industrial wastewater is the main source of an excessive amount of molybdenum (Mo) in natural ecosystems. It is necessary to remove Mo from wastewater before it is discharged into the environment. Molybdate ion(VI) is the most common form of Mo in natural reservoirs and industrial wastewater. In this work, the sorption removal of Mo(VI) from an aqueous medium was evaluated using aluminum oxide. The influence of such factors as the pH of the solution and the temperature was evaluated. Three adsorption isotherms, namely, Langmuir, Freundlich and Temkin, were used to describe the experimental results. It was found that the pseudo-first order kinetic model better fits the kinetic data of the adsorption process, and the maximum Mo(VI) adsorption capacity was 31 mg/g at 25 °C and pH 4. The thermodynamic parameters indicated that the process of Mo(VI) adsorption on AlO was exothermic and spontaneous. It was shown that the adsorption of Mo strongly depends on pH. The most effective adsorption was observed at pH values below 7. Experiments on adsorbent regeneration showed that Mo(VI) can be effectively desorbed from the aluminum oxide surface into a phosphate solution in a wide range of pH values. After the desorption of Mo(VI) in a phosphate solution, alumina was found to be suitable for repeating the procedure at least five times.
Topics: Molybdenum; Wastewater; Aluminum Oxide; Adsorption; Ecosystem; Thermodynamics; Phosphates; Hydrogen-Ion Concentration; Kinetics; Water Pollutants, Chemical
PubMed: 37240043
DOI: 10.3390/ijms24108700 -
Journal of Occupational and... Jul 2018Exposure to occupational aerosols are a known hazard in many industry sectors and can be a risk factor for several respiratory diseases. In this study, a laboratory...
Exposure to occupational aerosols are a known hazard in many industry sectors and can be a risk factor for several respiratory diseases. In this study, a laboratory evaluation of low-cost aerosol sensors, the Dylos DC1700 and a modified Dylos known as the Utah Modified Dylos Sensor (UMDS), was performed to assess the sensors' efficiency in sampling respirable and inhalable dust at high concentrations, which are most common in occupational settings. Dust concentrations were measured in a low-speed wind tunnel with 3 UMDSs, collocated with an aerosol spectrometer (Grimm 1.109) and gravimetric respirable and inhalable samplers. A total of 10 tests consisting of 5 different concentrations and 2 test aerosols, Arizona road dust and aluminum oxide, were conducted. For the Arizona road dust, total particle count was strongly related between the spectrometer and the UMDS with a coefficient of determination (R) between 0.86-0.92. Particle count concentrations measured with the UMDS were converted to mass and also were related with gravimetrically collected inhalable and respirable dust. The UMDS small bin (i.e., all particles) compared to the inhalable sampler yielded an R of 0.86-0.92, and the large bin subtracted from the small bin (i.e., only the smallest particles) compared to the respirable sampler yielded an R of 0.93-0.997. Tests with the aluminum oxide demonstrated a substantially lower relationship across all comparisons. Furthermore, assessment of intra-instrument variability was consistent for all instruments, but inter-instrument variability indicated that each instrument requires its own calibration equation to yield accurate exposure estimates. Overall, it appears that the UMDS can be used as a low-cost tool to estimate respirable and inhalable concentrations found in many workplaces. Future studies will focus on deployment of a UMDS network in an occupational setting.
Topics: Air Pollutants, Occupational; Aluminum Oxide; Arizona; Dust; Environmental Monitoring; Occupational Exposure; Particle Size; Particulate Matter
PubMed: 29683781
DOI: 10.1080/15459624.2018.1468565 -
Scientific Reports Jul 2021Herpes simplex virus is among the most prevalent sexually transmitted infections. Acyclovir is a potent, selective inhibitor of herpes viruses and it is indicated for...
Herpes simplex virus is among the most prevalent sexually transmitted infections. Acyclovir is a potent, selective inhibitor of herpes viruses and it is indicated for the treatment and management of recurrent cold sores on the lips and face, genital herpes, among other diseases. The problem of the oral bioavailability of acyclovir is limited because of the low permeability across the gastrointestinal membrane. The use of nanoparticles of pseudoboehmite as a drug delivery system in vitro assays is a promising approach to further the permeability of acyclovir release. Here we report the synthesis of high purity pseudoboehmite from aluminium nitrate and ammonium hydroxide containing nanoparticles, using the sol-gel method, as a drug delivery system to improve the systemic bioavailability of acyclovir. The presence of pseudoboehmite nanoparticles were verified by infrared spectroscopy, transmission electron microscopy, and X-ray diffraction techniques. In vivo tests were performed with Wistar rats to compare the release of acyclovir, with and without the addition of pseudoboehmite. The administration of acyclovir with the addition of pseudoboehmite increased the drug content by 4.6 times in the plasma of Wistar rats after 4 h administration. We determined that the toxicity of pseudoboehmite is low up to 10 mg/mL, in gel and the dried pseudoboehmite nanoparticles.
Topics: Acyclovir; Administration, Oral; Aluminum Hydroxide; Aluminum Oxide; Animals; Antiviral Agents; Biological Availability; Caco-2 Cells; Cell Survival; Drug Delivery Systems; Drug Liberation; Herpes Simplex; Humans; Models, Animal; Nanogels; Rats; Rats, Wistar; Simplexvirus
PubMed: 34326377
DOI: 10.1038/s41598-021-94325-y -
The Science of the Total Environment Nov 2022The geochemistry of copper (Cu) is generally assumed to be controlled by organic matter in soils. However, the role of clay and iron oxide minerals may be understated....
The geochemistry of copper (Cu) is generally assumed to be controlled by organic matter in soils. However, the role of clay and iron oxide minerals may be understated. Soil density fractionation, X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS) were combined to assess the long-term behavior of Cu in an agricultural soil subject to organic waste application. Two unprecedented molecular environments of natural Cu (i.e. Cu inherited from the parent rock) in soils are reported: Cu dimer in the interlayer of vermiculite and Cu structurally incorporated within hematite. Moreover, the soil naturally containing Cu-vermiculite, Cu-hematite, but also Cu-kaolinite (Cu = 122 mg·kg) was amended over 11 years with Cu-rich pig slurry in which Cu was 100 % Cu(I) sulfide. Natural Cu associated with clay and iron oxide minerals persisted in the amended soil, but the exogenous Cu(I) sulfide was unstable. The increase in Cu concentration in the amended soil to 174 mg·kg was accounted for the increase of Cu sorbed to kaolinite and Cu bound to organic matter. These results are important for better understanding the natural occurrence of Cu in soils and for assessing the environmental impacts of organic waste recycling in agricultural fields.
Topics: Aluminum Silicates; Animals; Clay; Copper; Ferric Compounds; Kaolin; Minerals; Soil; Soil Pollutants; Sulfides; Swine
PubMed: 35926606
DOI: 10.1016/j.scitotenv.2022.157779