Project description:Hospital acquired infections (HAIs) and the emergence of antibiotic resistant strains are major threats to human health. Copper is well known for its high antimicrobial efficacy, including the ability to kill superbugs and the notorious ESKAPE group of pathogens. We sought a material that maintains the antimicrobial efficacy of copper while minimizing the downsides - cost, appearance and metallic properties - that limit application. Here we describe a copper-glass ceramic powder as an additive for antimicrobial surfaces; its mechanism is based on the controlled release of copper (I) ions (Cu1+) from cuprite nanocrystals that form in situ in the water labile phase of the biphasic glass ceramic. Latex paints containing copper-glass ceramic powder exhibit ≥99.9% reduction in S. aureus, P. aeruginosa, K. aerogenes and E. Coli colony counts when evaluated by the US EPA test method for efficacy of copper-alloy surfaces as sanitizer, approaching that of benchmark metallic copper.
Project description:Water pollution is a big problem for the environment, and thus depollution, especially by adsorption processes, has garnered a lot of interest in research over the last decades. Since sorbents would be used in large quantities, ideally, they should be cheaply prepared in scalable reactions from waste materials or renewable sources and be reusable. Herein, we describe a novel preparation of a range of magnetic sorbents only from waste materials (sawdust and iron mud) and their performance in the adsorption of several dyes (methylene blue, crystal violet, fast green FCF, and congo red). The preparation is performed in a hydrothermal process and is thus easily scalable and requires little sophisticated equipment. The magnetic nanostructured materials were analyzed using FTIR, VSM, SEM/EDX, XRD, and XPS. For crystal violet as a pollutant, more in-depth adsorption studies were performed. It was found that the best-performing magnetic sorbent had a maximum sorption capacity of 97.9 mg/g for crystal violet (methylene blue: 149.8 mg/g, fast green FCF: 52.2 mg/g, congo red: 10.5 mg/g), could be reused several times without drastic changes in sorption behavior, and was easily separable from the solution by simply applying a magnet. It is thus envisioned to be used for depollution in industrial/environmental applications, especially for cationic dyes.
Project description:Aim The aim of this in vitro study was to evaluate the new, multilayered, translucent zirconia and enhanced glass-ceramics to determine if their translucency (TP) and color stability (?E) are affected by thermocycling at 10,000, 30,000, and 50,000 cycles. Materials & methods Two pre-shaded, multilayer zirconia products: Prettau® 2 Dispersive® (PRT) and Prettau® 4 Anterior® Multi® (PRTA), and two glass-ceramic: IPS e.max CAD® HT (E.max) and Vita Suprinity® HT (VS) were used. All were prepared and sectioned to get plate specimens with dimensions 12.5x14.5x1 mm (n=12) for each material. The L*a*b* values were recorded using a spectrophotometer before and after thermocycling for 10,000, 30,000, and 50000 cycles. The translucencies of the specimens were calculated using the TP formula and the color changes were giving by the color differences ?E formula at each interval. Results One-way analysis of variance (ANOVA) was used to analyze the data followed by Scheffe's post-hoc test and multiple paired t-tests (P < 0.05). There was a statistically significant higher TP for E.max before (16.2) and after aging (16.9) (p<0.001**). All the tested groups showed a statistically significant increase in their TP at different intervals. PRT showed significantly higher ?E (p<0.001**) after 50,000 cycles. Conclusion There was a mild but significant increase in translucency in both Zirconia and glass-ceramic after thermocycling. In addition, all materials showed a significant color change with time, however, this is not clinically perceptible.
Project description:Stimulated Raman scattering in transparent glass-ceramics (TGCs) based on bulk nucleating phase Ba2NaNb5O15 were investigated with the aim to explore the influence of micro- and nanoscale structural transformations on Raman gain. Nanostructured TGCs were synthesized, starting with 8BaO·15Na2O·27Nb2O5·50SiO2 (BaNaNS) glass, by proper nucleation and crystallization heat treatments. TGCs are composed of nanocrystals that are 10-15 nm in size, uniformly distributed in the residual glass matrix, with a crystallinity degree ranging from 30 up to 50% for samples subjected to different heat treatments. A significant Raman gain improvement for both BaNaNS glass and TGCs with respect to SiO2 glass is demonstrated, which can be clearly related to the nanostructuring process. These findings show that the nonlinear optical functionalities of TGC materials can be modulated by controlling the structural transformations at the nanoscale rather than microscale.
Project description:An investigation is made of wear mechanisms in a suite of dental materials with a ceramic component and tooth enamel using a laboratory test that simulates clinically observable wear facets. A ball-on-3-specimen wear tester in a tetrahedral configuration with a rotating hard antagonist zirconia sphere is used to produce circular wear scars on polished surfaces of dental materials in artificial saliva. Images of the wear scars enable interpretation of wear mechanisms, and measurements of scar dimensions quantify wear rates. Rates are lowest for zirconia ceramics, highest for lithium disilicate, with feldspathic ceramic and ceramic-polymer composite intermediate. Examination of wear scars reveals surface debris, indicative of a mechanism of material removal at the microstructural level. Microplasticity and microcracking models account for mild and severe wear regions. Wear models are used to evaluate potential longevity for each dental material. It is demonstrated that controlled laboratory testing can identify and quantify wear susceptibility under conditions that reflect the essence of basic occlusal contact. In addition to causing severe material loss, wear damage can lead to premature tooth or prosthetic failure.
Project description:Detailed research is carried out to ascertain the inhibitory effect of waste glass powder (WGP) on alkali-silica reaction (ASR) expansion induced by waste glass aggregate in this paper. The alkali reactivity of waste glass aggregate is examined by two methods in accordance with the China Test Code SL352-2006. The potential of WGP to control the ASR expansion is determined in terms of mean diameter, specific surface area, content of WGP and curing temperature. Two mathematical models are developed to estimate the inhibitory efficiency of WGP. These studies show that there is ASR risk with an ASR expansion rate over 0.2% when the sand contains more than 30% glass aggregate. However, WGP can effectively control the ASR expansion and inhibit the expansion rate induced by the glass aggregate to be under 0.1%. The two mathematical models have good simulation results, which can be used to evaluate the inhibitory effect of WGP on ASR risk.
Project description:Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.
Project description:As people spend more and more time inside, the quality of indoor air becomes crucial matter. This study explores the germicidal potential of two dark-operating germicidal composite materials designed to be applied for the indoor air disinfection under flow conditions. The first material, MnO2/AlPO4/γ-Al2O3 beads, is a donor-acceptor interactive composite capable of creating hydroxyl radicals HO∙. The second one is a ZnO/γ-Al2O3 material with intercropped hexagons on its surface. To determine the antimicrobial efficiency of these materials in life-like conditions, a pilot device was constructed that allows the test of the materials in dynamic conditions and agar diffusion inhibitory tests were also conducted. The results of the tests showed that the MnO2/AlPO4/γ-Al2O3 material has a germicidal effect in static conditions whereas ZnO/γ-Al2O3 does not. In dynamic conditions, the oxidizing MnO2/AlPO4/γ-Al2O3 material is the most efficient when using low air speed whereas the ZnO/γ-Al2O3 one becomes more efficient than the other materials when increasing the air linear speed. This ZnO/γ-Al2O3 dark-operating germicidal material manifests the ability to proceed the mechanical destruction of bacterial cells. Actually, the antimicrobial efficiency of materials in dynamic conditions varies regarding the air speed through the materials and that static tests are not representative of the behavior of the material for air disinfection. Depending on the conditions, the best strategy to inactivate microorganisms changes and abrasive structures are a field that needs further exploration as they are in most of the conditions tested the best way to quickly decrease the number of microorganisms.
Project description:High-density integration in single component used for mobile communication is highly demanded with the miniaturization trend in multi-functional light-weighted mobile communication devices. Embedding passive components into multi-layered ceramic chips is also increasingly needed for high integrity. The need for high strength materials to be used in handheld devices has also increased. To this end, many attempts to join different low-temperature co-fired ceramics (LTCC) materials with different dielectric constants have been made, but failed with de-laminations or internal cracks mainly due to difference of thermal expansion coefficients. It is thought that this difference could be minimized with the use of common glass in different LTCC materials. In this study, several candidates of common glass were mixed with various fillers of LTCC to have various dielectric constants in the radio-frequency, and to minimize the mismatch in joining. Ca-Al-Si-O glass was mixed with 1.3MgO-TiO2, cordierite and CaTiO3. Mixtures were tape-cast and sintered to be compared with their micro-structures, dielectric properties and thermo-mechanical characteristics. When 1.3MgO-TiO2 with volumetric ratio of 30% was mixed with Ca-Al-Si-O glass, the measured dielectric constant was 7.9, the quality factor was 3708. With 45 volumetric percent of cordierite, the dielectric constant was 5 and the quality factor was 1052.
Project description:PurposeTo assess the clinical performance of monolithic CAD-CAM lithium disilicate glass-ceramic (LDGC) crowns and metal-ceramic (MC) crowns provided by predoctoral students. This study also assessed the effects of patient and provider-related factors on their clinical performance as well as patient preference for these types of crowns.Materials and methodsTwenty-five patients who received 50 crowns (25 LDGC CAD-CAM and 25 MC) provided by predoctoral students were retrospectively examined. LDGC CAD-CAM crowns were milled in-house using the CEREC Bluecam system and cemented with either RelyX Unicem or Calibra Esthetic resin cements. MC crowns were cemented with RelyX Unicem cement. Clinical assessment of the crowns and the supporting periodontal structures were performed following the modified California Dental Association (CDA) criteria. Patients' preference was recorded using a visual analog scale (VAS). The results were statistically analyzed using log-rank test, Pearson Chi-squared test and Kaplan-Meier survival analysis.ResultsTwelve complications were observed in the MC crown group (9-esthetic, 2-technical and 1-biological). In comparison, 2 complications in the LDGC CAD-CAM crown group were observed (1-technical and 1-esthetic). The 6-year cumulative survival rates for MC crowns and LDGC CAD-CAM were 90.8% and 96%, respectively, whereas the success rates were 83.4% and 96%, respectively. Overall, patients preferred the esthetic outcomes of LDGC CAD-CAM crowns over MC crowns.ConclusionThe high survival and success rates, low number of complications, and the high level of patients' acceptance of monolithic LDGC CAD-CAM crowns lend them well as predictable and viable alternatives to the "gold standard" MC crowns.