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Molecules (Basel, Switzerland) Apr 2022Many people worldwide are exposed to extreme levels of fluoride in drinking water. It is, therefore, critical to develop inexpensive, locally available, and...
Many people worldwide are exposed to extreme levels of fluoride in drinking water. It is, therefore, critical to develop inexpensive, locally available, and environmentally friendly adsorbents for fluoride-laden water defluoridation. In the current study, virgin scoria (volcanic rock) from Ethiopia, was modified with zirconium oxide and used as an adsorbent in a fixed-bed column aiming at the removal of fluoride from water. The adsorption capability of zirconium oxide-coated scoria (ZrOCSc) was compared with unmodified virgin scoria (VSco). XRD, FTIR, XRF, SEM, ICP-OES, and the pH tests were evaluated to explore the adsorption mechanisms. Thermal analysis of VSco and ZrOCSc revealed lower total weight losses of 2.3 and 3.2 percent, respectively, owing to the removal of water molecules and OH species linked to metal oxides contained in the material. The effect of test conditions such as the pH of the solution and the influent flow rate on the adsorption capacity of the adsorbent was carefully studied. ZrOCSc exhibited the maximum removal capacity of 58 mg/kg, which was 4.46 times higher than the observations for VSco (13 mg/kg) at pH 2, and an initial flow rate of 1.25 mL/min. Breakthrough time increased with decreasing initial pH and flow rate. The adsorption experimental data under various test conditions were examined by the Thomas and Adams-Bohart models. Both models were found very effective in describing the experimental data with a correlation coefficient (R) of ≥0.976 (ZrOCSc) and ≥0.967 (VSco). Generally, coating VSco with zirconium oxide improved the adsorption performance of VSco; hence, a ZrOCSc-packed fixed bed could be employed for the decontamination of high levels of fluoride from groundwater. However, further examination of the adsorbent using natural groundwater is advisable to produce a definitive conclusion.
Topics: Adsorption; Fluorides; Humans; Hydrogen-Ion Concentration; Kinetics; Water; Water Pollutants, Chemical; Water Purification; Zirconium
PubMed: 35458725
DOI: 10.3390/molecules27082527 -
Proceedings of the National Academy of... Oct 2018We report a strategy to uniformly wrap bacteria with a metal-organic framework (MOF) monolayer of nanometer thickness for cytoprotection in artificial photosynthesis....
We report a strategy to uniformly wrap bacteria with a metal-organic framework (MOF) monolayer of nanometer thickness for cytoprotection in artificial photosynthesis. The catalytic activity of the MOF enclosure toward decomposition of reactive oxygen species (ROS) reduces the death of strictly anaerobic bacteria by fivefold in the presence of 21% O, and enables the cytoprotected bacteria to continuously produce acetate from CO fixation under oxidative stress. The high definition of the MOF-bacteria interface involving direct bonding between phosphate units on the cell surface and zirconium clusters on MOF monolayer, provides for enhancement of life throughout reproduction. The dynamic nature of the MOF wrapping allows for cell elongation and separation, including spontaneous covering of the newly grown cell surface. The open-metal sites on the zirconium clusters lead to 600 times more efficient ROS decomposition compared with zirconia nanoparticles.
Topics: Cell Survival; Cytoprotection; Metal-Organic Frameworks; Moorella; Oxidative Stress; Photosynthesis; Surface Properties; Zirconium
PubMed: 30275326
DOI: 10.1073/pnas.1808829115 -
Dental Materials : Official Publication... Mar 2016To quantify the splitting resistance of monolithic zirconia, lithium disilicate and nanoparticle-composite dental crowns.
OBJECTIVE
To quantify the splitting resistance of monolithic zirconia, lithium disilicate and nanoparticle-composite dental crowns.
METHODS
Fracture experiments were conducted on anatomically-correct monolithic crown structures cemented to standard dental composite dies, by axial loading of a hard sphere placed between the cusps. The structures were observed in situ during fracture testing, and critical loads to split the structures were measured. Extended finite element modeling (XFEM), with provision for step-by-step extension of embedded cracks, was employed to simulate full failure evolution.
RESULTS
Experimental measurements and XFEM predictions were self-consistent within data scatter. In conjunction with a fracture mechanics equation for critical splitting load, the data were used to predict load-sustaining capacity for crowns on actual dentin substrates and for loading with a sphere of different size. Stages of crack propagation within the crown and support substrate were quantified. Zirconia crowns showed the highest fracture loads, lithium disilicate intermediate, and dental nanocomposite lowest. Dental nanocomposite crowns have comparable fracture resistance to natural enamel.
SIGNIFICANCE
The results confirm that monolithic crowns are able to sustain high bite forces. The analysis indicates what material and geometrical properties are important in optimizing crown performance and longevity.
Topics: Bite Force; Composite Resins; Computer-Aided Design; Crowns; Dental Porcelain; Dental Stress Analysis; Finite Element Analysis; Materials Testing; Stress, Mechanical; Zirconium
PubMed: 26792623
DOI: 10.1016/j.dental.2015.12.010 -
Journal of the Mechanical Behavior of... Dec 2021Zirconia-based dental materials are extensively used in clinical practice due to their tooth-like appearance, biofunctionality, biocompatibility, and affordability.... (Review)
Review
Zirconia-based dental materials are extensively used in clinical practice due to their tooth-like appearance, biofunctionality, biocompatibility, and affordability. However, premature clinical failures of veneering porcelains raise a concern about their integrity. Extensive studies have been performed over a decade to resolve this issue, but it is challenging to reference all information effectively. A single source identifying the significance of potential parameters on material performance has not previously been available. An evidence-based meta-narrative review technique was used to review the characteristic parameters that can affect the overall behaviour of zirconia-based materials. Keywords were chosen to assess manuscripts based on scientific coherence with this paper's research objective. Online keyword searches were carried out on ScienceDirect, PubMed, and SAGE databases for relevant published manuscripts from year 1985-2020.261 out of 3170 identified manuscripts were included. A total of 10 parameters were identified and classified into the material, manufacturing, and geometric aspects. The effect of every parameter was reviewed on the performance of the material. A discrepancy in findings was observed and is attributed to the fact that there is no standard methodology. This review acts as a single source that summarizes various parameters' contribution to zirconia-based dental materials' performance. This review facilitates manufacturing improvements by accounting for every parameter's effect on overall performance.
Topics: Dental Porcelain; Dental Veneers; Zirconium
PubMed: 34600431
DOI: 10.1016/j.jmbbm.2021.104861 -
Srpski Arhiv Za Celokupno Lekarstvo 2013This article presents a literature review on the resin bond to zirconia ceramic. Modern esthetic dentistry has highly recognized zirconia, among other ceramic materials.... (Review)
Review
This article presents a literature review on the resin bond to zirconia ceramic. Modern esthetic dentistry has highly recognized zirconia, among other ceramic materials. Biocompatibility of zirconia, chemical and dimensional stability, excellent mechanical properties, all together could guarantee optimal therapeutical results in complex prosthodontic reconstruction. On the other hand, low thermal degradation, aging of zirconia as well as problematic bonding of zirconia framework to dental luting cements and tooth structures, opened the room for discussion concerning their clinical durability.The well known methods of mechanical and chemical bonding used on glass-ceramics are not applicable for use with zirconia. Therefore, under critical clinical situations, selection of the bonding mechanism should be focused on two important points: high initial bond strength value and long term bond strength between zirconia-resin interface. Also, this paper emphases the use of phosphate monomer luting cements on freshly air-abraded zirconia as the simplest and most effective way for zirconia cementation procedure today.
Topics: Dental Alloys; Dental Bonding; Dental Materials; Dental Restoration Failure; Humans; Materials Testing; Outcome Assessment, Health Care; Surface Properties; Zirconium
PubMed: 23858816
DOI: 10.2298/sarh1306395o -
Journal of Nuclear Medicine Technology Mar 2013This article is intended to provide an overview of the production and application of (89)Zr for the professional development of nuclear medicine technologists. It... (Review)
Review
UNLABELLED
This article is intended to provide an overview of the production and application of (89)Zr for the professional development of nuclear medicine technologists. It outlines the cyclotron targeting, separation and labeling options, and techniques for the preparation of the radionuclide (89)Zr (half-life, 78.4 h [3.3 d]) used in PET. Unlike the commonly used (18)F-FDG, with a 109.7-min half-life, the longer half-life of (89)Zr makes it possible to use high-resolution PET/CT to localize and image tumors with monoclonal antibody radiopharmaceuticals and thus potentially expand the use of PET.
METHODS
This paper briefly reviews the cyclotron technique of (89)Zr production and outlines the range and preparation techniques available for making (89)Y targets as a starting material. It then discusses how cyclotron-produced (89)Zr can be separated, purified, and labeled to monoclonal antibodies for PET/CT of specific tumors.
RESULTS
We argue that knowledge and understanding of this long-lived PET radionuclide should be part of the professional development of nuclear medicine technologists because it will lead to better patient outcomes and potentially increase the pool of collaborators in this field of research.
Topics: Animals; Cyclotrons; Humans; Positron-Emission Tomography; Radiochemistry; Radioisotopes; Radiopharmaceuticals; Zirconium
PubMed: 23327781
DOI: 10.2967/jnmt.112.111377 -
Biomedical Journal Oct 2019This issue of the Biomedical Journal honours the laureates of the 2018 Nobel Prize in Physiology and Medicine for their ground-breaking contributions to cancer...
This issue of the Biomedical Journal honours the laureates of the 2018 Nobel Prize in Physiology and Medicine for their ground-breaking contributions to cancer immunotherapy and unveils the identification of essential intermediates between microtubule-targeting agents and apoptosis. Subsequently, we learn about the hypoglycemic properties of natural phenolic acids, how cone-beam computed tomography assists dental implant surgery and which factors should be taken into account for salvage liver transplantation after recurrent hepatocellular carcinoma. Further readings discuss the negative impact of bismuth shields on computed tomography image quality, the predictive value of warning headaches for aneurysmal subarachnoid haemorrhage and the great long-term performance of zirconia implant abutments.
Topics: Humans; Immunotherapy; Medicine; Neoplasms; Zirconium
PubMed: 31783989
DOI: 10.1016/j.bj.2019.10.001 -
Clinical Oral Investigations Nov 2022To evaluate the wear resistance and abrasiveness of monolithic CAD/CAM ceramics.
OBJECTIVES
To evaluate the wear resistance and abrasiveness of monolithic CAD/CAM ceramics.
MATERIALS AND METHODS
Rectangular-shaped specimens (12 mm × 6.5 mm × 1.5 mm) were sectioned from the following CAD/CAM blocks (n = 10); partially crystallized lithium disilicate (PLD), experimental fully crystallized lithium disilicate (FLD), zirconia-reinforced lithium silicate (ZLS), super-translucent monolithic zirconia (SMZ), and ultra-translucent monolithic zirconia (UMZ). Silicon carbide papers were used to mechanically flatten and polish the surfaces. PLD specimens were subjected to a combined crystallization/glazing firing cycle. Ceramic specimens were mounted to the wear device and tested for 200,000 cycles against human premolars at 20 N force and 2 mm sliding distance. Artificial saliva was used as a lubricant. The teeth were scanned using micro-CT before and after the wear test and the generated models were overlapped to determine the volumetric tooth loss. Before and after the test, specimens' weights and surface roughness (R) values were measured, and the differences were calculated. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were utilized for microstructural and chemical analysis. Statistical analysis was performed using one-way ANOVA or an equivalent test for non-parametric results. Significance level was set at P ≤ 0.05.
RESULTS
The type of ceramic material affected the ceramic and antagonist wear rates (P < 0.001). PLD and ZLS had the highest ceramic and antagonist wear, whereas UMZ and SMZ demonstrated the lowest wear values. The FLD group showed comparable antagonist wear and significantly less ceramic wear than PLD and ZLS.
CONCLUSIONS
Monolithic zirconia demonstrated the best wear resistance and least abrasiveness to the antagonist. The experimental lithium disilicate was more wear-resistant than other glass-ceramic groups.
CLINICAL RELEVANCE
Monolithic zirconia is wear-resistant and gentle on the antagonist. In contrast, glass-ceramics are more abrasive to enamel.
Topics: Humans; Mastication; Materials Testing; Surface Properties; Dental Porcelain; Zirconium; Ceramics; Computer-Aided Design
PubMed: 35819543
DOI: 10.1007/s00784-022-04611-w -
BioMed Research International 2014Antibody based positron emission tomography (immuno-PET) imaging is of increasing importance to visualize and characterize tumor lesions. Additionally, it can be used to... (Review)
Review
Antibody based positron emission tomography (immuno-PET) imaging is of increasing importance to visualize and characterize tumor lesions. Additionally, it can be used to identify patients who may benefit from a particular therapy and monitor the therapy outcome. In recent years the field is focused on (89)Zr, a radiometal with near ideal physical and chemical properties for immuno-PET. In this review we will discuss the production of (89)Zr, the bioconjugation strategies, and applications in (pre-)clinical studies of (89)Zr-based immuno-PET in oncology. To date, (89)Zr-based PET imaging has been investigated in a wide variety of cancer-related targets. Moreover, clinical studies have shown the feasibility for (89)Zr-based immuno-PET to predict and monitor treatment, which could be used to tailor treatment for the individual patient. Further research should be directed towards the development of standardized and robust conjugation methods and improved chelators to minimize the amount of released Zr(4+) from the antibodies. Additionally, further validation of the imaging method is required. The ongoing development of new (89)Zr-labeled antibodies directed against novel tumor targets is expected to expand applications of (89)Zr-labeled immuno-PET to a valuable method in the medical imaging.
Topics: Antibodies; Humans; Molecular Imaging; Neoplasms; Positron-Emission Tomography; Radiography; Radioisotopes; Zirconium
PubMed: 24991539
DOI: 10.1155/2014/203601 -
Journal of Applied Oral Science :... Apr 2019To evaluate the radiopacity of Biodentine (BD) and BD associated with 15% calcium tungstate (BDCaWO4) or zirconium oxide (BDZrO2), by using conventional and digital...
OBJECTIVES
To evaluate the radiopacity of Biodentine (BD) and BD associated with 15% calcium tungstate (BDCaWO4) or zirconium oxide (BDZrO2), by using conventional and digital radiography systems, and their physicochemical and biological properties.
MATERIALS AND METHODS
Radiopacity was evaluated by taking radiographs of cement specimens (n=8) using occlusal film, photostimulable phosphor plates or digital sensors. Solubility, setting time, pH, cytocompatibility and osteogenic potential were also evaluated. Data were analyzed using one-way ANOVA and Tukey post-test or two-way ANOVA and Bonferroni post-test (α=0.05).
RESULTS
BD radiopacity was lower than 3 mm Al, while BD ZrO2 and BD CaWO4 radiopacity was higher than 3 mm Al in all radiography systems. The cements showed low solubility, except for BDCaWO4. All cements showed alkaline pH and setting time lower than 34 minutes. MTT and NR assays revealed that cements had greater or similar cytocompatibility in comparison with control. The ALP activity in all groups was similar or greater than the control. All cements induced greater production of mineralized nodules than control.
CONCLUSIONS
Addition of 15% ZrO2 or CaWO4 was sufficient to increase the radiopacity of BD to values higher than 3 mm Al. BD associated with radiopacifiers showed suitable properties of setting time, pH and solubility, except for BDCaWO4, which showed the highest solubility. All cements had cytocompatibility and potential to induce mineralization in Saos-2 cells. The results showed that adding 15% ZrO2 increases the radiopacity of BD, allowing its radiography detection without altering its physicochemical and biological properties.
Topics: Alkaline Phosphatase; Analysis of Variance; Anthraquinones; Calcium Compounds; Cell Survival; Humans; Hydrogen-Ion Concentration; Materials Testing; Osteoblasts; Radiography, Dental, Digital; Reference Values; Reproducibility of Results; Silicates; Solubility; Time Factors; Tungsten Compounds; Zirconium
PubMed: 30970115
DOI: 10.1590/1678-7757-2018-0429