Microstructure and Defect-Based Fatigue Mechanism Evaluation of Brazed Coaxial Ti/Al2O3 Joints for Enhanced Endoprosthesis Design

Alumina-based ceramic hip endoprosthesis heads have excellent tribological properties, such as low wear rates. However, stress peaks can occur at the point of contact with the prosthesis stem, increasing the probability of fracture. This risk should be minimized, especially for younger and active patients. Metal elevations at the stem taper after revision surgery without removal of a well-fixed stem are also known to increase the risk of fracture. A solution that also eliminates the need for an adapter sleeve could be a fixed titanium insert in the ceramic ball head, which would be suitable as a damping element to reduce the occurrence of stress peaks. A viable method for producing such a permanent titanium–ceramic joint is brazing. Therefore, a brazing method was developed for coaxial samples, and two modifications were made to the ceramic surface to braze a joint that could withstand high cyclic loading. This cyclic loading was applied in multiple amplitude tests in a self-developed test setup, followed by fractographic studies. Computed tomography and microstructural analyses—such as energy dispersive X-ray spectroscopy—were also used to characterize the process–structure–property relationships. It was found that the cyclic loading capacity can be significantly increased by modification of the surface structure of the ceramic.

A probabilistic model for fracture events of Petermann ice islands under the influence of atmospheric and oceanic conditions

Four calving events of Petermann Glacier happened in 2008, 2010, 2011, and 2012, which resulted in the drift and deterioration of numerous ice islands, some reaching as far as offshore Newfoundland. The presence of these ice islands in the eastern Canadian Arctic increases the risk of interaction with offshore operations and shipping activities. This study uses the recently developed Canadian Ice Island Drift, Deterioration and Detection database to investigate the fracture events that these ice islands experienced, and it presents a probabilistic model for the conditional occurrence of such events by analyzing the atmospheric and oceanic conditions that drive the causes behind the ice island fracture events. Variables representing the atmospheric and oceanic conditions that the ice islands were subjected to are extracted from reanalysis datasets and then interpolated to evaluate their distributions for both fracture and non-fracture events. The probability of fracture event occurrence for different combinations of input variable conditions is quantified using Bayes' theorem. Out of the seven variables analyzed in this study, water temperature and ocean current speed are identified as the most and least important contributors, respectively, to the fracture events of the Petermann ice islands. It is also revealed that the ice island fracture probability increases to 75 % as the ice islands encounter extreme (very high) atmospheric and oceanic conditions. A validation scheme is presented using the cross-validation approach and Pareto principle, and an average error of 13 %–39 % is reported in the fracture probability estimations. The presented probabilistic model has a predictive capability for future fracture events of ice islands and could be of particular interest to offshore and marine ice and risk management in the eastern Canadian Arctic. Future research, however, is necessary for model training and testing to further validate this ice island fracture model.

Comparison of Trabecular Bone Score-Adjusted FRAX™ and FRAX™-Bone Mineral Density in Postmenopausal Women with Clinical Vertebral Fractures: A Cross-Sectional, Analytic Study

Background: Ethnicity differentially modulate fracture risk prediction using FRAX™-bone mineral density (BMD). Objective: To compare FRAX™-BMD and trabecular bone score (TBS)-adjusted FRAX™ in the 10-year probability of fracture among Thai postmenopausal woman (PMW) with vertebral fracture (VF). Materials and Methods: The present study was a cross-sectional study conducted by retrospective review of medical records of PMW with VF older than 45 years undergoing lumbar and hip DXA scan. The authors excluded the PMW having been treated with metal implant at the spine, 3 or more lumbar VF, or cancer spreading to vertebral spine. The authors assessed the difference in means of normally distributed data by dependent sample t-test, the correlation between TBS and LS BMD by Pearson correlation, and the difference in proportions of PMW who met intervention threshold (IT) before and after TBS-adjusted FRAX™ by McNemar’s test. A p<0.05 was considered statistically significant. Results: Of the 119 patients, the mean age was 70.8±8.1 years. The mean 10-year probability of a hip fracture by TBS-adjusted FRAX™ was significantly higher than that by FRAX™-BMD with the mean difference of 0.44% (95% CI 0.13 to 0.76). The higher difference in means, using TBSadjusted FRAX™, was even significantly greater in the 10-year probability of major osteoporotic fractures. For either the IT of major osteoporotic fracture or hip fracture, TBS-adjusted FRAX™ resulted in four added PMWs who needed treatment, but without statistical significance. Conclusion: TBS-adjusted FRAX™ had a higher 10-year probability of fracture than FRAX™-BMD. Keywords: Trabecular bone score; FRAX™; Bone mineral density; Postmenopausal women; Osteoporosis

A probabilistic model for fracture events of Petermann ice islands under the influence of atmospheric and oceanic conditions

Four calving events of Petermann Glacier happened in 2008, 2010, 2011, and 2012, which resulted in the drift and deterioration of numerous ice islands, some reaching as far as offshore Newfoundland. The presence of these ice islands in the eastern Canadian Arctic increases the risk of interaction with offshore operations and shipping activities. This study used the recently developed Canadian Ice Island Drift, Deterioration and Detection database to investigate the fracture events that these ice islands experienced, and presented a probabilistic model for the conditional occurrence of such events by analyzing the atmospheric and oceanic conditions that drive the causes behind the ice island fracture events. Variables representing the atmospheric and oceanic conditions that the ice islands were subjected to were extracted from reanalysis datasets and then interpolated to evaluate their distributions for both fracture and non-fracture events. The probability of fracture event occurrence for different combinations of input variable conditions were quantified using Bayes theorem. Out of the seven variables analyzed in this study, water temperature and ocean current speed were identified as the most and least important contributors, respectively, to the fracture events of the Petermann ice islands. It was also revealed that the ice island fracture probability increased to 75 % as the ice islands encountered extreme (very high) atmospheric and oceanic conditions. A validation scheme was presented using cross-validation approach and Pareto principle, and an average error of 13–39 % was reported in the fracture probability estimations. The presented probabilistic model has a predictive capability for future fracture events of ice islands and could be of particular interest to offshore and marine activities in the eastern Canadian Arctic. Future research, however, is necessary for model training and testing to further validate the presented ice island fracture model.

The Behavior of Unconsolidated Rocks in California Waterfloods Under High-Pressure Gradients

Most waterfloods in California target sandstone formations that are unconsolidated in nature with high porosities and high permeabilities. These formations are also characterized by high Poisson ratios and low values of Young's Moduli. There has been a concern if, during the waterfloods of these types of formations, fracturing takes place at high-injection gradients. The influence of various factors on leak-off is studied in detail, indicating that with an increase in rock permeability, the leak-off velocity increases. This study included a comprehensive analysis of the characteristics of such soft formations and their responses to high injection gradients. We show that if the leak-off factors are adjusted to reflect high permeability and proper geomechanical properties, the probability of fracture formation is nil at injection gradients up to 0.9 psi/ft, for unconsolidated rooks. We computed estimated fracture width, fracture height, fracture length and noted for all three calculations, it takes gradients approaching 1psi/ft to note a non-trivial estimated value for these characteristics. This study shows that for unconsolidated formations like those in California targeted for waterfloods, the probability of fracture formation under pressure gradients of 0.9 psi/ft. is nil, and high injectivities can be exercised without the fear of fracture formation.

Evolution of contact performance of industry electrical connector based on reliability accelerated testing

The evolution of contact performance of electrical connectors, as an expression of service performance, played a significant role in various electronic equipment or system. However, very few methods had been used to detect the evolution of contact performance effectively and accurately. Hence, in this research, reliability accelerated testing was conducted to investigate the evolution of contact performance of electrical connectors. To detect the evolution of contact performance, contact resistance and friction and wear of the connector were measured using a DC resistance tester and an electron microscope respectively. Also, the effect of external conditions such as ambient temperature, mating speed, mating cycles was statistically investigated, and evolution curves were developed for contact resistance and abrasion loss. The obtained results revealed the temperature and mating speed affected the contact performance of electrical connectors. The increment of temperature reduced the shear strength of material and increased the thickness of oxide film. Increased mating speed greatly increased the probability of fracture of micro-protrusion due to collision, the wear form of connector had realized transition from low-speed adhesive wear to high-speed peeling wear. In addition, when the connector was mated about 3000 cycles, the contact performance of the connector would be greatly decreased.

The assessment of trabecular bone score to improve the sensitivity of FRAX in patients with type 2 diabetes mellitus

Aim. To estimate the trabecular bone score (TBS) for evaluation of fracture probability in order to make decisions about starting osteoporosis treatment in patients with type 2 diabetes mellitus (T2DM). Materials and methods. We obtained the bone mineral density (BMD) and trabecular bone score (TBS) using dual energy X-ray absorptiometry (iDXA) in patients with T2DM (with and without a history of osteoporotic fractures) versus the control group. Before and after TBS measurements we assessed the ten-year probability of fracture using the Fracture Risk Assessment Tool (FRAX). Results. We enrolled 48 patients with T2DM, including 17 with a history of low-traumatic fracture, 31 patients without fractures and 29 subjects of a control group. BMD was higher in patients with T2DM compared to the control group at L1L4 (mean T-score 0.44, 95% CI -3.2 4.9 vs mean T-score 0.33, 95% CI -2.9 3.0 in a control group p=0.052) and Total Hip (mean T-score 0.51, 95% CI -2.1 3.0 vs mean T-score -0.03, 95% CI -1.4 1.2 in a control group p=0,025). The TBS and 10-year probability of fracture (FRAX) was not different in patients with T2DM versus the control group. However, when the TBS was entered as an additional risk factor, the 10-year probability of fracture became higher in patients with T2DM (10-year probability of fracture in T2DM- 8.68, 95% CI 0.3-25.0 versus 6.68, 95% CI 0.415.0 in control group, p=0.04). Among patients with diabetes with and without fractures the FRAX score was higher in subjects with fractures, but no difference was found in regards to BMD or TBS. Entering BMD and TBS values into the FRAX tool in subjects with diabetes and fractures decreased the FRAX score. However, patients with low-traumatic fractures should be treated for osteoporosis without a BMD, TBS or FRAX assessment. Conclusion. TBS improves the results of FRAX assessment in patients with T2DM and should be entered while evaluating FRAX in patients with T2DM. However, additional research is needed to develop a more sensitive tool to evaluate fracture risk in patients with T2DM.

U-Shaped Association of Plasma Testosterone, and no Association of Plasma Estradiol, with Incidence of Fractures in Men

Purpose Whether androgens, distinct from estrogen, maintain bone health during male aging has implications for understanding osteoporosis. We assessed associations of different sex hormones with incidence of any bone fracture or hip fracture in older men. Participants and methods Analysis of 3307 community-dwelling men aged 76.8 ± 3.5 years, median follow-up period of 10.6 years. Plasma testosterone (T), dihydrotestosterone (DHT), and estradiol (E2) assayed by mass spectrometry, sex hormone-binding globulin (SHBG), and luteinizing hormone (LH) using immunoassay. Incident fractures determined via data linkage. We analyzed probability of fracture and performed Cox regression adjusted for age, medical comorbidities, and frailty. Results Incident fractures occurred in 330 men, including 144 hip fractures. Probability plots suggested nonlinear relationships between hormones and risk of any fracture and hip fracture, with higher risk at lower and higher plasma T, lower E2, higher SHBG, and higher LH. In fully adjusted models, there was a U-shaped association of plasma T with incidence of any fracture (Quartile 2 [Q2] versus Q1: fully adjusted hazard ratio [HR] = 0.69, 95% confidence interval [CI] 0.51–0.94, P = .020; Q3: HR 0.59, 95% CI 0.42–0.83, P = .002) and hip fracture (Q2 versus Q1: HR 0.60, 95% CI 0.37–0.93, P = .043; Q3: HR 0.52, 95% CI 0.31–0.88, P = .015). DHT, E2, and LH were not associated with fracture. Higher SHBG was associated with hip fracture (Q4 versus Q1: HR 1.76, 95% CI 1.05–2.96, P = .033). Conclusions Midrange plasma T was associated with lower incidence of any fracture and hip fracture, and higher SHBG with increased risk of hip fracture. Circulating androgen rather than estrogen represents a biomarker for hormone effects on bone driving fracture risk.

Machine learning-based fracture-hit detection algorithm using LFDAS signal

Low-frequency distributed acoustic sensing (LFDAS) signal has been used to detect fracture hits at offset monitor wells during hydraulic fracturing operations. Typically, fracture hits are manually identified, which can be subjective and inefficient. We implemented machine learning-based models using supervised learning techniques in order to identify fracture zones, which demonstrate a high probability of fracture hits automatically. Several features are designed and calculated from LFDAS data to highlight fracture-hit characterizations. A simple neural network model is trained to fit the manually picked fracture hits. The fracture-hit probability, as predicted by the model, agrees well with the manual picks in training, validation, and test data sets. The algorithm was used in a case study of an unconventional reservoir. The results indicate that smaller cluster spacing design creates denser fractures.

Crohn Disease and Fracture Risk Assessment With FRAX

Background Studies are inconsistent whether people with Crohn disease (CD) have an increased fracture risk. This study showed that patients with Crohn’s disease (CD) had a higher ten year probability of fracture, assessed by the fracture assessment tool FRAX, and more fractures, but the proportion of CD patients with a fracture was not significantly higher than that of controls. Methods Forty-nine CD and 49 controls participated. All 98 completed a health questionnaire. A score with the fracture assessment tool FRAX &gt; 15% was considered risk factor for fracture. Results Mean FRAX score for 49 CD was 10.1 ± 10.3% and for 49 controls 5.0 ± 3.9% (P = 0.002). The variables correlated with fracture were being female (P = 0.04) and having a fractured mother (P = 0.002). Conclusion The CD group had significantly higher FRAX scores and more fractures, but the proportion of CD subjects with a fracture was not significantly higher than that of controls.