Influence of Framework Material and Posterior Implant Angulation in Full-Arch All-on-4 Implant-Supported Prosthesis Stress Concentration

This study evaluated the influence of distal implants angulation and framework material in the stress concentration of an All-on-4 full-arch prosthesis. A full-arch implant-supported prosthesis 3D model was created with different distal implant angulations and cantilever arms (30° with 10-millimeter cantilever; 45° with 10-millimeter cantilever and 45° with 6-millimeter cantilever) and framework materials (Cobalt–chrome [CoCr alloy], Yttria-stabilized tetragonal zirconia polycrystal [Y-TZP] and polyetheretherketone [PEEK]). Each solid was imported to computer-aided engineering software, and tetrahedral elements formed the mesh. Material properties were assigned to each solid with isotropic and homogeneous behavior. The contacts were considered bonded. A vertical load of 200 N was applied in the distal region of the cantilever arm, and stress was evaluated in Von Misses (σVM) for prosthesis components and the Maximum (σMAX) and Minimum (σMIN) Principal Stresses for the bone. Distal implants angled in 45° with a 10-millimeter cantilever arm showed the highest stress concentration for all structures with higher stress magnitudes when the PEEK framework was considered. However, distal implants angled in 45° with a 6-millimeter cantilever arm showed promising mechanical responses with the lowest stress peaks. For the All-on-4 concept, a 45° distal implants angulation is only beneficial if it is possible to reduce the cantilever’s length; otherwise, the use of 30° should be considered. Comparing with PEEK, the YTZP and CoCr concentrated stress in the framework structure, reducing the stress in the prosthetic screw.

Evaluation of a Porous Imine-Based Covalent Organic Framework for Solid-Phase Extraction of Nitroimidazoles

Covalent organic framework materials (COFs), a kind of porous organic material, have excellent potential application in the field of sample pretreatment due to their high surface areas and thermal stability....

Hierarchical Porous Metal-Organic Framework Materials for Efficient Oil-Water Separation

Oil contaminated water is a global issue, decreasing the quality of water sources and is posing a threat to the health of humans and many ecosystems. The utilization of industrial...

Light alkane oxidation over well-defined active sites in metal–organic framework materials

We review structure–catalytic property relationships for MOF materials used in the direct oxidation of light alkanes, focusing specifically on the elucidation of active site structures and probes for reaction mechanisms.

Application of Metal-organic Framework Materials (MOFs) in the photocatalytic CO2 Reduction：A mini review

In recent years, the effective use of CO2 has become one of the research hotspots worldwide to solve environmental pollution and energy shortage, whose excessive emission led to increasingly serious global environmental problems. Metal-organic frameworks (MOFs), with extraordinary specific surface areas, tunable surface chemistry, fast electron migration rate, large CO2 adsorption capacity, etc． are a new class of functional materials composed of metal ions/clusters and organic ligands, which have broad application potential in CO2 photocatalytic reduction. This paper systematically generalized the composition of the structure, discussed the methods of synthetics and expounded the photocatalytic properties and photocatalytic mechanism of MOFs. In addition, the application and research progress of MOFs functional materials in recent research are reviewed. The article also summarized challenges and prospects for the large-scale photocatalytic applications of MOFs catalysts. It guides the preparation of novel modified MOFs photocatalysts for high-efficiency applications in the field of CO2 reduction and photocatalytic degradation of dyes.

Study on Lubrication and Friction Reduction Properties of ZIF-8 Nanoparticles as Si3N4 Ceramic Water Lubrication Additives

Ceramics can achieve superlubricity under water lubrication; however, their running-in period is long and application is rather limited by wear limit. Thus, zeolite imidazole ester skeleton (ZIF), an important branch of metal organic framework materials (MOFs), is expected to improve the tribological properties of lubricants and associated additives. As such, it has broad application prospects within the field. In this paper, ZIF-8 nanoparticles of varying concentrations were prepared and linked with amino functional groups. Specimens were used in silicon nitride self-matching pairs and their tribological properties were observed. After the experiment, friction surfaces were analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and Fourier transform infrared radiation (FTIR). The experimental results have shown that ZIF-8 nanoparticles greatly reduced both friction and wear. Comprehensively considering running-in time, average COF during the whole process and smooth friction period COF, optimal performance was obtained for the ZIF-8 nanoparticle solution concentration of 1wt%. Furthermore, it was concluded that the lubrication properties of amino-modified ZIF-8 nanoparticles are significantly better compared to that of the unmodified ZIF-8. The anti-friction mechanism of ZIF-8 as a ceramic water lubrication additive was mainly through the filling and forming of nanoparticle film on the ceramic surface.