Evaluation of bond strength between zirconia milled ceramic material and veneered dental porcelain.

This study aimed at examining the bond strength between zirconia and ceramic veneer, following the ISO 9693 guidelines. A total of fifty specimens of zirconia/ceramic-veneer system were produced using two commercial zirconias (VITA YZ-HTWhite and Zolid HT+ White, referred to as Group A and Group B, respectively) and a ceramic-veneering material (Zirkonia 750). The microstructure (via x-ray diffraction analysis, XRD and Secondary Electron mode, SEM) and the mechanical properties (via 3-point bending tests) of the two groups were assessed. Then, experiments were conducted according to the ISO 9693 and conventional protocols applied for producing zirconia/ceramic-veneer restorations. Bond strength values, measured by 3-point bending tests, were 34.42 ± 7.60 MPa for Group A and 31.92 ± 6.95 MPa for Group B. SEM observations of the cohesively fractured surfaces (on the porcelain side) and the examination for normality using the Shapiro-Wilk test suggested the use of Weibull statistical analysis. Median strength (σ50%) for Group A and Group B was 34.76 and 32.22 MPa, while the characteristic strength (σ63.2%) was 35.78 and 33.14 MPa, respectively. The Weibull modulus disparity between groups (12.69 and 13.07) was not significant. Bond strength exceeded the ISO 9693 minimum of 20 MPa, suggesting satisfactory strength for clinical use.

Simulating porcelain firing effect on the structure, corrosion and mechanical properties of Co-Cr-Mo dental alloy fabricated by soft milling.

This study aims at evaluating the effect of simulating porcelain firing on the microstructure, corrosion behavior and mechanical properties of a Co-Cr-Mo alloy fabricated by Metal Soft Milling (MSM). Two groups of Co-28Cr-5Mo specimens (25 × 20 × 3 mm) were prepared by MSM: The as-sintered (AS) specimens and the post-fired (PF) specimens that were subjected to 5 simulating porcelain firing cycles without applying the ceramic mass onto their surface. Phase identification by X-ray Diffraction (XRD), microstructure examination by optical microscopy and Scanning Electron Microscopy combined with Energy-Dispersive X-ray Spectroscopy (SEM/EDX), corrosion testing by cyclic polarization and chronoamperometry in simulated body fluid (SBF), the latter test accompanied by Cr3+ and Cr6+ detection in the electrolyte through the 1.5-diphenylcarbazide (DPC) method and UV/visible spectrophotometry, and mechanical testing by micro-/nano-indentation were conducted to evaluate the effect of the post-firing cycles on the properties of Co-Cr-Mo. The results were statistically analyzed by the t test (p < 0.05: statistically significant). All specimens had a mixed γ-fcc and ε-hcp cobalt-based microstructure with a dispersion of pores filled with SiO2 and a fine M23C6 intergranular presence. PF led to an increase in the ε-Co content and slight grain coarsening. Both AS and PF alloys showed high resistance to general and localized corrosion, whereas neither Cr6+ nor Cr3+ were detected during the passivity-breakdown stage. PF improved the mechanical properties of the AS-alloy, especially the indentation modulus and true hardness (statistically significant differences: p = 0.0009 and 0.006, respectively). MSM and MSM/simulating-porcelain firing have been proven trustworthy fabrication methods of Co-Cr-Mo substrates for metal-ceramic prostheses. Moreover, the post-firing cycles improve the mechanical behavior of Co-Cr-Mo, which is vital under the dynamically changing loads in the oral cavity, whereas they do not degrade the corrosion performance.

Microstructure, physical and mechanical properties of dental polychromic multilayer zirconia of uniform composition.

The present study aimed to compare the microstructure, physical, and mechanical properties of three commercially available dental polychromatic multilayer zirconia materials of uniform composition: Dima Mill Zirconia ML, VITA YZ/ST Multicolor, and VITA YZ/XT Multicolor (with 3, 4, and 5 mol% Y2 O3 , respectively); thus, the influence of Y2 O3 content on the above properties of the produced materials was experimentally studied. Homogeneous zirconia ceramics with a dense micro- and nanostructure, without pores or defects, were produced after milling the blocks and sintering, which resulted in yttrium-stabilized tetragonal and cubic zirconia. Statistical analysis of the results of measurable magnitudes was performed by the one-way ANOVA test. The increase of Y2 O3 content (from 3 to 5 mol%) favored larger grain and crystallite sizes and a decrease of the values of the mechanical properties; yet, the differences were statistically insignificant. Clinically, these differences are expected to have no impact on their function in the oral cavity, both in terms of their fracture propensity and the damage that can be caused to the opposing teeth. Accordingly, the experimental results qualify the polychromic multilayer zirconia ceramics of uniform composition fabricated by milling technology for use in dental restorations.

Mo2 C-Based Ceramic Electrode with High Stability and Catalytic Activity for Hydrogen Evolution Reaction at High Current Density.

Developing robust electrodes with high catalytic performance is a key step for expanding practical HER (hydrogen evolution reaction) applications. This paper reports on novel porous Mo2 C-based ceramics with oriented finger-like holes directly used as self-supported HER electrodes. Due to the suitable MoO3 sintering additive, high-strength (55 ± 6 MPa) ceramic substrates and a highly active catalytic layer are produced in one step. The in situ reaction between MoO3 and Mo2 C enabled the introduction of O in the Mo2 C crystal lattice and the formation of Mo2 C(O)/MoO2 heterostructures. The optimal Mo2 C-based electrode displayed an overpotential of 333 and 212 mV at 70 °C under a high current intensity of 1500 mA cm-2 in 0.5 m H2 SO4 and 1.0 m KOH, respectively, which are markedly better than the performance of Pt wire electrode; furthermore, its price is three orders of magnitude lower than Pt. The chronopotentiometric curves recorded in the 50 - 1500 mA cm-2 range, confirmed its excellent long-term stability in acidic and alkaline media for more than 260 h. Density functional theory (DFT) calculations showed that the Mo2 C(O)/MoO2 heterostructures has an optimum electronic structure with appropriate *H adsorption-free energy in an acidic medium and minimum water dissociation energy barrier in an alkaline medium.

Microstructural features, physicο-mechanical properties, and wear behavior of dental translucent polychromic multilayer zirconia of hybrid composition prepared by milling technology.

OBJECTIVE: The present study determined the mechanical properties and the wear behavior, as results of the micro(nano)structure, of the enamel, transition, and dentine layers, which comprise the polychromic multilayer zirconia materials of hybrid composition fabricated by milling technology. MATERIALS AND METHODS: Prismatic blocks were fabricated from two commercial pre-sintered dental polychromic multilayer zirconia materials of hybrid composition, IPS e.max ZirCAD Prime (medium and high translucency, from the dentine to the incisal layer) and 3D Pro ML (translucency gradient, from the dentine to the incisal layer) by milling technique, and then, cut into 3 distinct parts to separate the enamel, transition, and dentine layers. The samples were sintered, thermally treated (similarly to the glazing procedure), and polished for characterization. Their microstructure, mechanical properties (determined by nanoindentation and microhardness), and wear behavior (evaluated by scratch test), were examined. RESULTS: The produced materials had a homogeneous and dense nanostructure, where the grain size decreased from the enamel to dentine layer. The mechanical properties decreased from the dentine to enamel layer. However, the three layers manifested similar dynamic friction coefficient. CONCLUSION: The differences in the above properties in the three layers negligibly influenced the wear behavior of the entire multilayer zirconia material. CLINICAL SIGNIFICANCE: The properties of dental restorations produced from polychromic multilayer zirconia of hybrid composition by milling technology (i.e., strong, non-fragile, and esthetic materials), anticipate good performance in oral cavity.

Nano-silica anti-icing coatings for protecting wind-power turbine fan blades.

Wind power is a promising electricity source. Nevertheless, wind turbine blade icing can cause severe problems in turbine operation. In this study, SiO2 spherical nanoparticles (∼90 nm), produced by RF (radio frequency) plasma spheroidization, were mixed with E51, PDMS, and ethyl acetate, and sprayed on the surface of aluminum plates and regular power windmill fan blades which were already coated with polyurethane primer. XPS and IR spectroscopies revealed the development of SiC and SiPh (Ph = phenolic ring) bonds, whose formation should be favored by the ultrasound and curing processes at 50 °C. The integrity of the coating/substrate interface, whose strength is ascribed to hydrogen bonds, was maintained after 100 icing-melting cycles. The coatings display superhydrophobic behavior and excellent anti-icing performance, along with stability in abrasion, sunlight and self-cleaning ability towards solid pollutants.

Influence of heat treatment on the microstructure and the physical and mechanical properties of dental highly translucent zirconia.

PURPOSE: Microstructural and physico-mechanical characterization of highly translucent zirconia, prepared by milling technology (CAD-CAM) and repeated firing cycles, was the main aim of this in vitro study. MATERIALS AND METHODS: Two groups of samples of two commercial highly-translucent yttria-stabilized dental zirconia, VITA YZ-HTWhite (Group A) and Zolid HT + White (Group B), with dimensions according to the ISO 6872 "Dentistry - Ceramic materials", were prepared. The specimens of each group were divided into two subgroups. The specimens of the first subgroups (Group A1 and Group B1) were merely the sintered specimens. The specimens of the second subgroups (Group A2 and Group B2) were subjected to 4 heat treatment cycles. The microstructural features (microstructure, density, grain size, crystalline phases, and crystallite size) and four mechanical properties (flexural strength, modulus of elasticity, Vickers hardness, and fracture toughness) of the subgroups (i.e. before and after heat treatment) were compared. The statistical significance between the subgroups (A1/A2, and B1/B2) was evaluated by the t-test. In all tests, P values smaller than 5% were considered statistically significant. RESULTS: A homogenous microstructure, with no residual porosity and grains sized between 500 and 450 nm for group A and B, respectively, was observed. Crystalline yttria-stabilized tetragonal zirconia was exclusively registered in the X-ray diffractograms. The mechanical properties decreased after the heat treatment procedure, but the differences were not statistically significant. CONCLUSION: The produced zirconia ceramic materials can be safely (i.e., according to the ISO 6872) used in extensive fixed prosthetic restorations, such as substructure ceramics for three-unit prostheses involving the molar restoration and substructure ceramics for prostheses involving four or more units. Consequently, milling technology is an effective manufacturing technology for producing zirconia substructures for dental fixed all-ceramic prosthetic restorations.

COVID-19 persuaded lockdown impact on local environmental restoration in Pakistan.

Coronavirus disease 2019 (COVID-19) pandemic adversely affected human beings. The novel coronavirus has claimed millions of lives all over the globe. Most countries around the world, including Pakistan, restricted people's social activities and ordered strict lockdowns throughout the country, to control the fatality of the novel coronavirus. The persuaded lockdown impact on the local environment was estimated. In the present study, we assessed air quality changes in four cities of Pakistan, namely Islamabad, Karachi, Lahore, and Peshawar, based on particulate matter (PM2.5), using "Temtop Airing 1000," which is capable of detecting and quantifying PM2.5. The Air Quality Index (AQI) was evaluated in three specific time spans: the COVID-19 pandemic pre- and post-lockdown period (January 1, 2020 to March 20, 2020, and May 16, 2020 to June 30, 2020 respectively), and the COVID-19 pandemic period (March 21 2020 to May 15, 2020). We compared land-monitored AQI levels for the above three periods of time. For validation, air quality was navigated by the Moderate Resolution Imaging Spectrometer (MODIS) satellite during the first semester (January 1 to June 30) of 2019 and 2020. It is seen that the concentration of PM2.5 was considerably reduced in 2020 (more than 50%), ranging from ~ 0.05 to 0.3 kg⋅m3, compared to the same period in 2019. The results revealed that the AQI was considerably reduced during the lockdown period. This finding is a very promising as the inhabitants of the planet Earth can be guaranteed the possibility of a green environment in the future.

Robust Porous WC-Based Self-Supported Ceramic Electrodes for High Current Density Hydrogen Evolution Reaction.

Developing an economical, durable, and efficient electrode that performs well at high current densities and is capable of satisfying large-scale electrochemical hydrogen production is highly demanded. A self-supported electrocatalytic "Pt-like" WC porous electrode with open finger-like holes is produced through industrial processes, and a tightly bonded nitrogen-doped WC/W (WC-N/W) heterostructure is formed in situ on the WC grains. The obtained WC-N/W electrode manifests excellent durability and stability under multi-step current density in the range of 30-1000 mA cm-2 for more than 220 h in both acidic and alkaline media. Although WC is three orders of magnitude cheaper than Pt, the produced electrode demonstrates comparable hydrogen evolution reaction performance to the Pt electrode at high current density. Density functional theory calculations attribute its superior performance to the electrode structure and the modulated electronic structure at the WC-N/W interface.

Evaluation of adverse effects of particulate matter on human life.

Particulate matter (PM2.5) has a severe impact on human health. The concentration of PM2.5, related to air-quality changes, may be associated with perceptible effects on people's health. In this study, computer intelligence was used to assess the negative effects of PM2.5. The input data, used for the evaluation, were grid definitions (shape-file), PM2.5, air-quality data, incidence/prevalence rates, a population dataset, and the (Krewski) health-impact function. This paper presents a local (Pakistan) health-impact assessment of PM2.5 in order to estimate the long-term effects on mortality. A rollback-to-a-standard scenario was based on the PM2.5 concentration of 15 µg m-3. Health benefits for a population of about 73 million people were calculated. The results showed that the estimated avoidable mortality, linked to ischemic heart disease and lung cancer, was 2,773 for every 100,000 people, which accounts for 2,024,290 preventable deaths of the total population. The total cost, related to the above mortality, was estimated to be US $ 1,000 million. Therefore, a policy for a PM2.5-standard up to 15 µg m-3 is suggested.

Mechanism of upconversion luminescence enhancement in Yb3+/Er3+ co-doped Y2O3 through Li+ incorporation.

Li+ doping is a well-known, simple, yet efficient strategy to optimize the properties of upconverting materials. Nonetheless, the position of Li+ in the lattice and the mechanism of upconversion enhancement are still controversial, especially in Yb3+/Er3+ co-doped Y2O3. This paper presents a comprehensive investigation of the above issues (i.e. the position occupied by Li+ in the lattice and the mechanism of luminescence enhancement, in terms of decreased defects) by studying (Y0.78-XYb0.20Er0.02LiX)2O3 powders. Neutron powder diffraction was employed for the first time in the literature to show that Li+ ions are accommodated in Y sites of YO6 octahedra, confirmed also by the content of oxygen defects, which was increased with the increase of Li+ concentration. FT-IR showed that there was a small change in the amount and the type of the surface-absorbed groups with the increase in the Li+ content, thus not supporting the prevailing conclusion that the quenching groups are decreased by doping Li+. Positron annihilation lifetime (PLAS) experiments showed that the total defect concentration and the large defect clusters, which are considered as quenching centers, are decreased with increasing Li+-content, resulting in the enhancement of the emission intensity in Yb3+/Er3+ co-doped Y2O3.

Simple Fabrication of Concrete with Remarkable Self-Cleaning Ability, Robust Superhydrophobicity, Tailored Porosity, and Highly Thermal and Sound Insulation.

Self-cleaning materials have attracted immense commercial and academic interests in recent years. A major challenge is the scalable and cost-effective fabrication of three-dimensional bulk materials with remarkable self-cleaning and a desirable combination of tailored porosity, robust superhydrophobicity, excellent mechanical strength, heat insulation, and sound absorption ability. Here, self-cleaning concrete was achieved in one step through the combination of the liquid template pore formation and in situ bulk hydrophobic modification. The concrete exhibited superhydrophobicity with a high water contact angle of 166° both on the surface and inside of the sample, which qualified the sample with remarkable stain repellency and long-term stability. The water contact angle remained unchanged under continuous mechanical grinding and harsh environments, such as high temperature (450 °C in air and 650 °C in Ar) and chemical erosion. The concrete with a controllable porosity from 56.3 to 77.4% and homogeneous small pore size (∼15 µm) exhibited high compressive strength and low thermal conductivity. Furthermore, high sound absorption capacity (97%, 500 Hz) at a vibration frequency from 400 to 600 Hz was realized. With these excellent performances and characteristics and easy scalable fabrication, the concrete prepared in this work possessed a wide application prospect.

Multifunctional Thin-Film Nanofiltration Membrane Incorporated with Reduced Graphene Oxide@TiO2@Ag Nanocomposites for High Desalination Performance, Dye Retention, and Antibacterial Properties.

High desalination performance, dye retention, and antibacterial properties were achieved with a multifunctional thin-film nanocomposite (MTFN) membrane, fabricated by the incorporation of a novel nanocomposite structure of reduced graphene oxide@TiO2@Ag (rGO@TiO2@Ag) into the polyamide active layer. The specific characteristics of the graphene-based nanocomposite, synthesized by the microwave-assisted irradiation process, favored water channelization and provided superhydrophilicity and antibacterial properties to the MTFN membranes. In comparison with the conventional methods, such as multistep chemical process using strong agents for reduction and long-term energy-consuming hydrothermal process, microwave irradiation facilitated a green, fast, and cost-effective route for the fabrication of GO-based nanocomposites for multifunctional applications. Interfacial polymerization was performed on a polyethersulfone/Si3N4 robust hollow fiber substrate using m-phenylenediamine aqueous solution and 1,3,5-benzenetricarbonyltrichloride organic solution. The structural and chemical characteristics of the synthesized nanocomposites and the MTFN membranes were thoroughly studied by a series of characterization analyses (transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy). The physicochemical properties and the nanofiltration performance of the MTFN membranes were investigated after the incorporation of rGO@TiO2@Ag at various concentrations. The water contact angles confirmed the superb surface hydrophilicity of the MTFN membranes. High permeability (52 L·m-2·h-1), desalination (96% for 1 g/L Na2SO4 feed solution), and dye retention (98% for 0.5 g/L rose bengal feed solution) were recorded for MTFN enriched with 0.2 wt % rGO@TiO2@Ag. A 90% reduction in the number of viable bacteria ( Escherichia coli), after 3 h of contact with MTFN membranes, confirmed the superior antibacterial activity of the produced membranes.

Effect of Bonding Agent on Metal-Ceramic Bond Strength between Co-Cr Fabricated with Selective Laser Melting and Dental Feldspathic Porcelain.

PURPOSE: To investigate the effect of bonding agent on the bonding strength between Co-Cr dental alloy, prepared by selective laser melting (SLM), and feldspathic porcelain. MATERIALS AND METHODS: The experiments were conducted according to ISO 9693 and the conventional protocols for the production of metal-ceramic dental restorations. After Al2 O3 air-particle abrasion, metal substrates of Co-Cr dental alloy specimens were bonded, using bonding agent (25 specimens), with dental porcelain positioned in layers (opaque, dentin, enamel). Control specimens (25) were also produced without bonding agent. Bonding strength was measured using 3-point bending tests, and the results were statistically analyzed using the t-test and Weibull statistics. Elemental (by SEM/EDS) and crystallographic analyses (by XRD) were conducted on the bonding agent, along cross sections of alloy-porcelain interfaces, and on fracture surfaces. RESULTS: Cohesive fracture occurred (on the porcelain side). The application of the bonding agent decreased the average bonding strength (from 42.27 ± 5.85 to 36.25 ± 3.26 MPa, P = 0.00006), attributed to the nonexisting reaction between the TiO2 -rich bonding agent and the Co-Cr alloy, but it increased the Weibull modulus (from 7.84 to 12.16), which reflects the reliability of the bond in the tested metal-ceramic specimens. CONCLUSIONS: Although the application of bonding agent slightly decreased the bonding strength, all the measured values of the metal-ceramic specimens produced by the SLM technique, with or without the bonding agent, are markedly higher than the minimum value required by ISO 9693 (25 MPa). Moreover, the use of bonding agent favors the increase of the Weibull modulus.

Optimization of Ca2+ content in alginate hydrogel injected in myocardium.

The spontaneous uptake of Ca2+ -ions is a unique property of alginate hydrogels, which, along with their high biocompatibility, disintegration (approximately within 2 weeks), and morphological similarity to heart tissue, makes them attractive as scaffolding materials in therapies in infarct myocardium. To shed light on the aforementioned ability, thorough theoretical calculations were carried out with the density functional theory (DFT) method. The influence of Ca-content οn the molecular structure and the thermodynamic stability of the alginate hydrogel was determined; what is more, these results effectively interpreted the experimental findings, as well. This analysis suggests that in Ca-free or Ca-deficient alginates spontaneous Ca2+ cations uptake can occur from the biological environment and develop, via chelation reaction, a well-formed and thermodynamically stable hydrogel in situ inside the tissue. The highest degree of cross linking results in viscosity peak. Nevertheless, further increase of Ca-content in alginate structure beyond this peak results in products with poorer thermodynamic stability. Structural optimization DFT calculations revealed that the destabilization of the Ca-rich alginate hydrogels is attributed to changes of the alginate chain molecule, which are relaxation, weakening, and eventually total collapse of the bond between the units of the alginate chain. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 223-231, 2019.

Medium-term Electrophysiologic Effects of a Cellularized Scaffold Implanted in Rats After Myocardial Infarction.

Background Cardiac repair strategies are being evaluated for myocardial infarctions, but the safety issues regarding their arrhythmogenic potential remain unresolved. By utilizing the in-vivo rat model, we have examined the medium-term electrophysiologic effects of a biomaterial scaffold that has been cellularized with spheroids of human adipose tissue, derived from mesenchymal stem cells and umbilical vein endothelial cells. Methods Mesenchymal stem cells, which exhibit adequate differentiation capacity, were co-cultured with umbilical vein endothelial cells and were seeded on an alginate based scaffold. After in-vitro characterization, the cellularized scaffold was implanted in (n=15) adult Wistar rats 15 min post ligation of the left coronary artery, with an equal number of animals serving as controls. Two weeks thereafter, monophasic action potentials were recorded and activation-mapping was performed with a multi-electrode array. An arrhythmia score for inducible ventricular tachyarrhythmias was calculated after programmed electrical stimulation. Results The arrhythmia score was comparable between the treated animals and controls. No differences were detected in the local conduction at the infarct border and in the voltage rise in monophasic action potential recordings. Treatment did not affect the duration of local repolarization, but tended to enhance its dispersion. Conclusions The fabricated bi-culture cellularized scaffold displayed favorable properties after in-vitro characterization. Medium-term electrophysiologic assessment after implantation in the infarcted rat myocardium revealed low arrhythmogenic potential, but the long-term effects on repolarization dispersion will require further investigation.

The crystal structure and luminescence properties of a novel green-yellow emitting Ca1.5Mg0.5Si1-xLixO4-δ:Ce3+ phosphor with high quantum efficiency and thermal stability.

A novel green-yellow emitting Ca1.5Mg0.5Si1-xLixO4-δ:Ce3+ phosphor with high quantum efficiency and thermal stability was discovered for applications in near ultraviolet pumped white light-emitting diodes. Its crystal structure was determined with a single-particle diagnosis approach. The Si sites in the SiO4 tetrahedra are reported for the first time to accommodate Li+ ions. This substitution, confirmed by 6Li solid-state NMR and T.O.F. neutron powder diffraction, causes a disordered occupation of Ca/Mg in the Ca3MgSi2O8 host and favors a phase transformation at ∼330 °C, which results in the formation of the novel phosphor. The produced phosphor was efficiently excited by near UV light peaking at 365 and 410 nm and produced broad green-yellow emission with peaks at 500 and 560 nm, respectively. Its quantum efficiency reached 88.4% (internal) and 55.7% (external) under excitation at 365 nm, and 80.5% (internal) and 42.7% (external) under excitation at 410 nm, while the decrease of luminescence intensity at 200 °C was small (∼26%). A WLED lamp with a high color rendering index of Ra = 92.8 was produced with the combination of a 365 nm emitting chip with blue emitting BaMgAl10O17:Eu2+, green-yellow emitting CMSL:0.01Ce, and red emitting Sr2Si5N8:Eu2+ phosphors.

Preparation of a Porous, Sintered and Reaction-Bonded Si3N4 (SRBSN) Planar Membrane for Filtration of an Oil-in-Water Emulsion with High Flux Performance.

A porous, sintered, and reaction-bonded Si3N4 (SRBSN) planar membrane was prepared by phase-inversion tape-casting, nitridation (at 1350 °C), and sintering (at 1650 °C) of silicon slurry. The membrane was comprised of uniform rod-like β-Si3N4 crystals with a large length/diameter ratio and had high porosity and bending strength. The prepared membrane features a typical asymmetric structure with a skin layer, a sponge layer, and finger-like voids and an average pore size of 0.61 μm. A high permeation flux of 367 L m−2 h−1 and an oil rejection of 88.6% were recorded in oil-in-water emulsion separation experiments. These results suggest that SRBSN membranes have excellent potential for the treatment of oily wastewater.

Synthesis of Si, N co-Doped Nano-Sized TiO2 with High Thermal Stability and Photocatalytic Activity by Mechanochemical Method.

Τhe photocatalytic activity in the range of visible light wavelengths and the thermal stability of the structure were significantly enhanced in Si, N co-doped nano-sized TiO2, and synthesized through high-energy mechanical milling of TiO2 and SiO2 powders, which was followed by calcination at 600 °C in an ammonia atmosphere. High-energy mechanical milling had a pronounced effect on the mixing and the reaction between the starting powders and greatly favored the transformation of the resultant powder mixture into an amorphous phase that contained a large number of evenly-dispersed nanocrystalline TiO2 particles as anatase seeds. The experimental results suggest that the elements were homogeneously dispersed at an atomic level in this amorphous phase. After calcination, most of the amorphous phase was crystallized, which resulted in a unique nano-sized crystalline-core/disordered-shell morphology. This novel experimental process is simple, template-free, and provides features of high reproducibility in large-scale industrial production.

Synthesis, characterization, and biological properties of composites of hydroxyapatite and hexagonal boron nitride.

Hydroxyapatite (HA), obtained from bovine bones, was successfully reinforced with hexagonal boron nitrite (h-BN). h-BN/HA composites, with BN content up to 1.5 wt %, were sintered at various temperatures between 1000 and 1300°C, in air. Well-sintered samples were obtained after sintering at 1200 and 1300°C. The presence of h-BN contributed to dense, fine, and well-crystallized microstructure. The results of X-ray diffraction analysis and FT-IR spectroscopy showed that the produced composites comprised biphasic ß-TCP/HCA (HCA: carbonate partially substituted HA). High values of mechanical properties were achieved, namely compression strength 155 MPa for the sample 0.5% h-BN/HA and Vickers microhardness of 716 HV for the samples 1.5% h-BN/HA, both sintered at 1300°C. U2OS human bone osteosarcoma proliferation and cell viability showed no adverse effect in the presence of h-BN/HA, suggesting the potential use of the produced materials as safe biomaterials in bone tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2384-2392, 2018.