Characterization of high-fracture toughness K-fluorrichterite-fluorapatite glass ceramics

Stoichiometric K-fluorrichterite (Glass A) and the same composition with 2 mol% P2O5 added (Glass B) were prepared and then heat-treated isothermally from 550°1000°C with 50°C intervals. Samples were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The biaxial flexural strength and indentation fracture toughness of heat-treated glass specimens were also determined for both materials. XRD traces and TEM images showed similar phase evolution and fine microstructures for both systems at ≤950°C, with mica and diopside reacting with residual glass to form K-fluorrichterite as the temperature was increased from 650°C. However, in Glass B, fluorapatite was also present at >800°C. In contrast, coarser microstructures were observed at 1000°C, with larger K-fluorrichterite (20 μm) and enstatite (10 μm) crystals in Glasses A and B, respectively. The highest fracture toughness (2.69 ± 0.01 MPa·m(1/2)) and biaxial strength (242.6 ± 3.6 MPa) were recorded for Glass B heat-treated at 1000°C. This was attributed to the presence of enstatite coupled with an interlocked lath-like crystalline microstructure

Progress in Bioactive Metal and, Ceramic Implants for Load- Bearing Application

The field of biomaterials is an exuberant and enticing field, attracting interest across a number of scientific disciplines. Synthetic materials such as metals and ceramics have helped civilisation accomplish many feats, and this can also be said for the achievements in orthopaedic applications. Metals and ceramics have achieved success in non-load-bearing applications and attempts are made to translate the accomplishments into weight-bearing applications. For this, a material needs to be porous but with sufficient strength to withstand daily loading; however, both properties are mutually exclusive. The implant must also avoid causing adverse reactions and toxicity and, preferably, bond to the surrounding tissues. Metals such as stainless steels and chromium-cobalt alloys have been used due to their excellent mechanical properties that can withstand daily activities, but retrospective studies have alluded to the possibilities of significant adverse reaction when implanted within the human body, caused by the elution of metal ions. Lessons from metals have also demonstrated that materials with significantly higher mechanical properties will not necessarily enhance the longevity of the implant—such is the complexity of the human body. Ceramics, on the other hand, exhibit excellent biocompatibility, but their mechanical properties are a significant hindrance for load-bearing use. Thus, the chapter herein provides a select overview of contemporary research undertaken to address the aforementioned drawbacks for both metals and ceramics. Furthermore, the chapter includes a section of how metals and ceramics can be combined in a multi-material approach to bring together their respective properties to achieve a desirable characteristics

Well, I wouldn\u27t be any worse off, would I, than I am now? A qualitative study of decision-making, hopes, and realities of adults with type 1 diabetes undergoing islet cell transplantation

BACKGROUND: For selected individuals with type 1 diabetes, pancreatic islet transplantation (IT) prevents recurrent severe hypoglycemia and optimizes glycemia, although ongoing systemic immunosuppression is needed. Our aim was to explore candidates and recipients\u27 expectations of transplantation, their experience of being on the waiting list, and (for recipients) the procedure and life posttransplant. METHODS: Cross-sectional qualitative research design using semistructured interviews with 16 adults (8 pretransplant, 8 posttransplant; from 4 UK centers (n = 13) and 1 Canadian center (n = 3)). Interviews were audio-recorded, transcribed, and underwent inductive thematic analysis. RESULTS: Interviewees were aged (mean ± SD) 52 ± 10 years (range, 30-64); duration of diabetes, 36 ± 9 years (range, 21-56); 12 (75%) were women. Narrative accounts centered on expectations, hopes, and realities; decision-making; waiting and uncertainty; the procedure, hospital stay, and follow-up. Expected benefits included fewer severe hypoglycemic episodes, reduced need for insulin, preventing onset/progression of complications and improved psychological well-being. These were realized for most, at least in the short term. Most interviewees described well-informed, shared decision-making with clinicians and family, and managing their expectations. Although life "on the list" could be stressful, and immunosuppressant side effects were severe, interviewees reported "no regrets." Posttransplant, interviewees experienced increased confidence, through freedom from hypoglycemia and regained glycemic control, which tempered any disappointment about continued reliance on insulin. Most viewed their transplant as a success, though several reflected upon setbacks and hidden hopes for becoming "insulin-free." CONCLUSIONS: Independently undertaken interviews demonstrated realistic and balanced expectations of IT and indicate how to optimize the process and support for future IT candidates

Effect of climate change and mining on hydrological connectivity of surficial layers in the Athabasca Oil Sands Region

This is the peer reviewed version of the following article: Kompanizare M, Petrone RM, Shafii M, Robinson DT, Rooney RC. Effect of climate change and mining on hydrological connectivity of surficial layers in the Athabasca Oil Sands Region. Hydrological Processes. 2018;32:3698–3716. https://doi.org/10.1002/hyp.13292, which has been published in final form at https://doi.org/10.1002/hyp.13292. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.This research analyses the impact of climate change and surface mining activities on the hydrologic connectivity of surficial (soil and geological) layers located in a watershed in the Athabasca Oil Sands Region. Surface water and groundwater flow are simulated for the period 2014–2080 under four climate scenarios: median (M), double precipitation (DP), no change in precipitation (NP), and double temperature (DT) and with the assumption of no change in the extent of mine activities after 2013. The results demonstrate that the annual growing season duration is longer and snowmelt happens earlier in the year 2080. During the growing season, the daily proportion of connected hydrologic units (DPCUs) remains approximately the same in the future under the different climate scenarios. It appears that around 68% of watershed area, mostly in western and central eastern portions, will be frequently connected (annual proportion of connected days [APCD] ≥ 20%) in the future. This area remains hydrologically connected for more than 20–50% of the year. Results also show that mining areas are located in infrequently connected areas (APCD < 20%), where DPCU values are significantly lower than other areas. DPCUs in forestlands are more stable with a growing season, that is, ~15 days longer than in wetlands. Comparisons between hydrologic responses in 2016 and 2080 show that, in 2080, maximum snow depths are about 0.7 times smaller, evapotranspiration is ~0.05 mm higher, capillary soil moisture in DT and NP scenarios are 1.01–1.52 mm lower, and the ratio of precipitation to potential evapotranspiration is almost the same during the growing season. However, at the end of growing season, the ratio is ~1 unit less in 2080 in DT and NP scenarios. Results also demonstrate that thinner surficial geological layers in the mining areas (located mostly in downstream part of the watershed) lead to their lower hydrologic connectivities. Therefore, these areas are more vulnerable to mining activity impacts, and their hydrologic response under a changing climate should be considered in reclamation planning.Husky Energy (Rooney, Petrone, Robinson) || Natural Sciences and Engineering Research Council of Canada (HEAD3; Petrone

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data