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1.
Recovery of ilmenite mud as an additive in commercial Portland cements.
Llanes, MC, González, MJG, Moreno, SMP, Raya, JPB
Environmental science and pollution research international. 2018;(25):24695-24703
Abstract
This work is focused on the manufacture of commercial cement using as additive ilmenite mud, a waste generated during TiO2 pigment production. The cements were produced by adding different proportions of mud (2.5, 5 and 10 wt%) to ordinary Portland cement (OPC). The ilmenite mud and the ilmenite mud cements (IMCs) were characterised physico-chemically by X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS) and X-ray diffraction (XRD). Moreover, the technological properties of the IMCs were evaluated and compared with a reference material (OPC). Since waste from the TiO2 industry is classified as a NORM (naturally occurring radioactive material), the concentrations of radionuclides were measured by high-resolution low-background gamma and alpha spectrometry techniques. Finally, the TCLP leaching test (Toxicity Characteristic Leaching Procedure, USEPA), the radiological index ("I") and the Ra equivalent concentration were also calculated to evaluate the environmental risks. As a final conclusion, it can be pointed out that the addition of ilmenite mud to OPC plays a beneficial role since it reduces the heat of hydration, the final setting time, the expansion and the linear retraction compared to standard OPC. The compression strength improves with the addition of up to 5 wt% mud. Moreover, the environmental impact of IMC2.5 and IMC5 can be considered negligible.
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2.
Titanium and polyether ether ketone (PEEK) patient-specific sub-periosteal implants: two novel approaches for rehabilitation of the severely atrophic anterior maxillary ridge.
Mounir, M, Atef, M, Abou-Elfetouh, A, Hakam, MM
International journal of oral and maxillofacial surgery. 2018;(5):658-664
Abstract
The aim of this study was to assess two new protocols for single-stage rehabilitation of the severely atrophic maxillary ridge using customized porous titanium or polyether ether ketone (PEEK) sub-periosteal implants. Ten patients with a severely atrophic anterior maxillary alveolar ridge were divided randomly into two groups (five patients in each) to receive customized sub-periosteal implants fabricated via CAD/CAM technology: group 1, porous titanium implants; group 2, PEEK implants. Prosthetic loading with fixed acrylic bridges was performed 1 month postoperative. The implants were followed-up for 12 months and evaluated for the presence of any sign of radiographic bone resorption, mobility, infection, prosthetic fracture, or implant exposure. The immediate postoperative period was uneventful except for one case complicated by wound dehiscence in group 1. At 12 months, all implants were functionally stable and the patients were comfortable with the prostheses. No signs of radiographic bone resorption, mobility, infection, or prosthetic fracture were observed. Within the limitations of this study, the application of customized porous titanium and PEEK sub-periosteal implants produced through CAD/CAM technology appears to be an acceptable method for single-stage prosthetic rehabilitation of the severely atrophic edentulous anterior maxilla. This study was awarded the best case study at the academy of osseintegration annual meeting 2017, Orlando, Florida.
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3.
Rehabilitation of Postextractive Socket in the Premaxilla: A 12-Year Study on 27 Titanium Plasma Spray Resorbable Calcium Phosphate Coated Single Implants.
Perrotti, V, Vozza, I, Tumedei, M, Pompa, G, Iaculli, F, Quaranta, A
Implant dentistry. 2018;(4):452-460
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Abstract
OBJECTIVES The purpose of this study was to evaluate the peri-implant bone tissue level on postextractive resorbable calcium phosphate coated single implants placed in premaxillary sites grafted with autologous bone, anorganic bovine bone (ABB), platelet-rich plasma (PRP), and keratinized epithelial connective graft over 12 years. MATERIALS AND METHODS A total of 27 patients received a postextractive single implant in premaxillary sites grafted with ABB and PRP. Two months later, a keratinized epithelial connective graft was applied and the implants loaded. Clinical and radiographical evaluations were performed at baseline, 6 and 18 months, 4 and 6 years after the implant insertion, and then every 2 years up to the 12th year. RESULTS After 12 years, a total of 22 implants (81.48%), were available for the final data analysis; the implants achieved a 100% cumulative survival rate, and only a mild degree of periodontal tissue inflammation was recorded. The radiographic evaluation revealed a physiological marginal bone remodeling over the follow-up. CONCLUSION Although a good preservation of the residual bone tissue in postextraction implant sites treated with keratinized epithelial connective tissue grafts was observed, the low number of treated cases does not allow us to propose this experimental protocol to all cases of bone defects but it certainly represents a new option. Further studies on a greater number of patients and using implants with different surface characteristics should be conducted for a better understanding of the indications of the proposed treatment.
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4.
Osteoblastic differentiating potential of dental pulp stem cells in vitro cultured on a chemically modified microrough titanium surface.
DE Colli, M, Radunovic, M, Zizzari, VL, DI Giacomo, V, DI Nisio, C, Piattelli, A, Calvo Guirado, JL, Zavan, B, Cataldi, A, Zara, S
Dental materials journal. 2018;(2):197-205
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Abstract
Titanium surface modification is critical for dental implant success. Our aim was to determine surfaces influence on dental pulp stem cells (DPSCs) viability and differentiation. Implants were divided into sandblasted/acid-etched (control) and sandblasted/acid-etched coated with calcium and magnesium ions (CaMg), supplied as composite (test). Proliferation was evaluated by MTT, differentiation checking osteoblastic gene expression, PGE2 secretion and matrix formation, inflammation by Interleukin 6 (IL-6) detection. MTT and IL-6 do not modify on test. A PGE2 increase on test is recorded. BMP2 is higher on test at early experimental points, Osterix and RUNX2 augment later. Alizarin-red S reveals higher matrix production on test. These results suggest that test surface is more osteoinductive, representing a start point for in vivo studies aiming at the construction of more biocompatible dental implants, whose integration and clinical performance are improved and some undesired effects, such as implant stability loss and further surgical procedures, are reduced.
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5.
Effect of calcium ions on peptide adsorption at the aqueous rutile titania (110) interface.
Sultan, AM, Hughes, ZE, Walsh, TR
Biointerphases. 2018;(6):06D403
Abstract
How the presence of Ca2+ ions at the aqueous TiO2 interface influences the binding modes of two experimentally identified titania-binding peptides, Ti-1 and Ti-2, is investigated using replica exchange with solute tempering molecular dynamics simulations. The findings are compared with available experimental data, and the results are contrasted with those obtained under NaCl solution conditions. For Ti-1, Ca2+ ions enhance the adsorption of the negatively charged Asp8 residue in this sequence to the negatively charged surface, via Asp–Ca2+–TiO2 bridging. This appears to generate a nonlocal impact on the adsorption of Lys12 in Ti-1, which then pins the peptide to the surface via direct surface contact. For Ti-2, fewer residues were predicted to adsorb directly to the surface in CaCl2, compared with predictions made for NaCl solution, possibly due to competition between the other peptide residues and Ca2+ ions to adsorb to the surface. This reduction in direct surface contact gives rise to a more extensive solvent-mediated contact for Ti-2. In general, the presence of Ca2+ ions resulted in a loss of conformational diversity of the surface-adsorbed conformational ensembles of these peptides, compared to counterpart data predicted for NaCl solution. The findings provide initial insights into how peptide–TiO2 interactions might be tuned at the molecular level via modification of the salt composition of the liquid medium.
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6.
Bioabsorbable magnesium versus standard titanium compression screws for fixation of distal metatarsal osteotomies - 3 year results of a randomized clinical trial.
Plaass, C, von Falck, C, Ettinger, S, Sonnow, L, Calderone, F, Weizbauer, A, Reifenrath, J, Claassen, L, Waizy, H, Daniilidis, K, et al
Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association. 2018;(2):321-327
Abstract
BACKGROUND For the treatment of hallux valgus commonly distal metatarsal osteotomies are performed. Persistent problems due to the hardware and the necessity of hardware removal has led to the development of absorbable implants. To overcome the limitations of formerly used materials for biodegradable implants, recently magnesium has been introduced as a novel implant material. This is the first study showing mid-term clinical and radiological (MRI) data after using magnesium implants for fixation of distal metatarsal osteotomies. MATERIAL AND METHODS 26 patients with symptomatic hallux valgus were included in the study. They were randomly selected to be treated with a magnesium or standard titanium screw for fixation of a modified distal metatarsal osteotomy. The patients had a standardized clinical follow up and MRI investigation 3 years' post-surgery. The clinical tests included the range of motion of the MTP 1, the AOFAS, FAAM and SF-36 scores. Further on the pain was evaluated on a VAS. RESULTS Eight patients of the magnesium group and 6 of the titanium group had a full clinical and MRI follow up 3 years postoperatively. One patient was lost to follow-up. All other patients could be interviewed, but denied full study participation. There was a significant improvement for all tested clinical scores (AOFAS, SF-36, FAAM, Pain-NRS) from pre-to postoperative investigation, but no statistically relevant difference between the groups. Magnesium implants showed significantly less artifacts in the MRI, no implant related cysts were found and the implant was under degradation three years postoperatively. CONCLUSION In this study, bioabsorbable magnesium implants showed comparable clinical results to titanium standard implants 3 years after distal modified metatarsal osteotomy and were more suitable for radiologic analysis. LEVEL OF EVIDENCE 2.
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7.
Potential Causes of Titanium Particle and Ion Release in Implant Dentistry: A Systematic Review.
Delgado-Ruiz, R, Romanos, G
International journal of molecular sciences. 2018;(11)
Abstract
Implant surface characteristics, as well as physical and mechanical properties, are responsible for the positive interaction between the dental implant, the bone and the surrounding soft tissues. Unfortunately, the dental implant surface does not remain unaltered and changes over time during the life of the implant. If changes occur at the implant surface, mucositis and peri-implantitis processes could be initiated; implant osseointegration might be disrupted and bone resorption phenomena (osteolysis) may lead to implant loss. This systematic review compiled the information related to the potential sources of titanium particle and ions in implant dentistry. Research questions were structured in the Population, Intervention, Comparison, Outcome (PICO) framework. PICO questionnaires were developed and an exhaustive search was performed for all the relevant studies published between 1980 and 2018 involving titanium particles and ions related to implant dentistry procedures. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed for the selection and inclusion of the manuscripts in this review. Titanium particle and ions are released during the implant bed preparation, during the implant insertion and during the implant decontamination. In addition, the implant surfaces and restorations are exposed to the saliva, bacteria and chemicals that can potentially dissolve the titanium oxide layer and, therefore, corrosion cycles can be initiated. Mechanical factors, the micro-gap and fluorides can also influence the proportion of metal particles and ions released from implants and restorations.
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8.
Exposure of Microcystis aeruginosa to hydrogen peroxide and titanium dioxide under visible light conditions: Modeling the impact of hydrogen peroxide and hydroxyl radical on cell rupture and microcystin degradation.
Chang, CW, Huo, X, Lin, TF
Water research. 2018;:217-226
Abstract
The aims of this study are to evaluate, under visible light conditions, the ability of H2O2 and TiO2 to produce OH, their quantitative impacts on the cell integrity of Microcystis, and the subsequent release and degradation of microcystins (MCs). A sequential reaction model was developed, including one sub-model to simulate the rupture kinetics for cell integrity of Microcystis, and another to describe the release and degradation of MCs. For cell rupture, the dual-oxidant Delayed Chick-Watson model (DCWM) and dual-oxidant Hom model (HM) were first proposed and developed, giving excellent simulation results of cell rupture kinetics. Kinetic rate constants between Microcystis cells and H2O2 [Formula: see text] as well as OH (k•OH, Cell) under visible light successfully separated the individual effects of H2O2 and OH on Microcystis. The dual-oxidant models were further validated with additional experiments, making the models more convincing. Finally, the dual-oxidant cell rupture models were integrated with the MC degradation model and well predicted the observed MCs concentrations in the experimental systems. The results of this study not only demonstrate the potential application of H2O2 and TiO2 for the control of cyanobacteria and metabolites in natural water bodies, but also provide a new methodology to differentiate the individual contributions of the two oxidants, H2O2 and OH, on cell rupture, thus giving a novel way to more precisely determine the effective doses of applied oxidants for cyanobacteria control.
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9.
Using Data Mining To Search for Perovskite Materials with Higher Specific Surface Area.
Shi, L, Chang, D, Ji, X, Lu, W
Journal of chemical information and modeling. 2018;(12):2420-2427
Abstract
The specific surface area (SSA) of ABO3-type perovskite is one of the important properties associated with photocatalytic ability. In this work, data mining methods were used to explore the relationship between the SSA (in the range of 1-60 m2 g-1) of perovskite and its features, including chemical compositions and technical parameters. The genetic algorithm-support vector regression method was used to screen the main features for modeling. The correlation coefficient ( R) between the predicted and experimental SSAs reached as high as 0.986 for the training data set and 0.935 for leave-one-out cross-validation. ABO3-type perovskites with higher SSA can be screened out using the Online Computation Platform for Materials Data Mining (OCPMDM) developed in our laboratory. Further, an online web server has been developed to share the model for the prediction of SSA of ABO3-type perovskite, which is accessible at http://118.25.4.79/material_api/csk856q0fulhhhwv .
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10.
Light induced DNA-functionalized TiO2 nanocrystalline interface: Theoretical and experimental insights towards DNA damage detection.
Murti, BT, Putri, AD, Kanchi, S, Sabela, MI, Bisetty, K, Inamuddin, , Asiri, AM
Journal of photochemistry and photobiology. B, Biology. 2018;:159-176
Abstract
Owing to the emerging applications of DNA-functionalized TiO2 nanocrystals towards DNA damage detection, it is inevitable to understand the better chemistry as well as in-depth molecular interaction phenomena. Fundamentally, energy difference underlies the layer-by-layer construction, resulted in the increase of the interaction energy and thus, altering the electrochemical behavior. Herein, Density functional theory (DFT) calculations were performed using DMol3 and DFTB+ codes successfully to elucidate the structural, electronics, and vibrational properties of the layer-by-layer components composing ss-DNA/dopamine/TiO2/FTO. The obtained results are in good agreement with the experimental findings. The band gaps of FTO and TiO2 were computationally obtained at 3.335 and 3.136 eV which are comparable with the experimental data (3.500 eV; FTO and 3.200 eV; TiO2). Frontier orbital analysis is also considered to elucidate their electron transfer phenomena. Further, a 100 ns MD simulations are carried out using canonical ensemble embedded with COMPASS-Universal Forcefields generating useful thermodynamics parameters. Binding energies indicate increasing interaction energies for the layer-by-layer nanosystem, in agreement with the increasing diameter of electrochemical impedance spectroscopy (EIS) semicircle. Our results reveal the fundamental understanding of the DNA-functionalized TiO2 nanocrystals down to molecular and electronic level and further, paving a way of its application towards nanoelectrochemical DNA biosensors.