Fatigue Assessment of Defect-Free and Defect-Containing Brazed Steel Joints

This work aims at the development of lifetime estimation procedures for defect-free and defect-containing brazed joints. Preliminary investigations were performed to measure the influence of specimen geometry on the joint strength. To estimate the influence of defects on the fatigue lifetime, defect-free specimens were compared with specimens containing defects. The experiments show that defect-containing specimens provide considerably lower joint strengths than defect-free specimens. The decrease of the fatigue strength with increasing defect size can be shown, but the direct comparison of different defects is not possible with S-N-curves. Based on the experimental results and on theoretical investigations, a procedure was developed to estimate the lifetime of defect-free and defect-containing brazed joints based on the stress intensity caused by a defec

Stroke Education to Reduce Adult Stroke Risk: An Evidence-Based Quality Initiative

Paper approved May 2019 by the faculty of UMKC in partial fulfillment of the degree of Doctor of Nursing PracticeA stroke can have a devastating effect on a person’s health and life expectancy. Implementation of beneficial and relevant prevention strategies, such as reducing weight, increasing physical activity, and smoking cessation, have the potential to reduce the burden of stroke. The purpose of the quasi-experimental, single group study was to determine if evidence-based stroke education reduces primary stroke risk within a five-month period. Ten adults, 18 years and older who scored in the caution or high category of the National Stroke Association’s stroke risk scorecard were included in the study. Convenience sampling was conducted at a primary care clinic in Missouri. The intervention consisted of one-to-one participant education with evidence-based stroke education materials. Follow-up interviews and lifestyle data kept participants motivated to reduce stroke risk. The primary outcome expected was a reduction of stroke risk measured by the National Stroke Association’s stroke risk scorecard. Secondary outcomes included a greater knowledge base of stroke, measured by the National Institute of Health’s stroke knowledge survey, along with an increase in physical exercise, weight reduction, and smoking cessation. By using evidence-based stroke education, participants reduced their stroke risk by 30%. Secondary outcome results included 50% of participants partaking in exercise, 10% with smoking cessation, and 20% with a reduced body mass index. Stroke can cause grave physical and mental disability resulting in prolonged hospitalizations, long-term care, and economic losses. Through a review of evidence-based practice, reduced stroke risk can benefit society by reducing the health burden of stroke

Evaluation of essential oils as an alternative to conventional antibiotic

The purpose of this study was to determine if synergistic interactions between essential oils can increase their antibacterial efficacy by testing essential oils. The following combinations were assessed for effective inhibition of E.coli and S. aureus growth: tea tree oil as the control solution, tea tree/oregano solution, tea tree/thyme solution, and tea tree/wintergreen solution. A Kirby-Bauer disc diffusion was employed to assess antibiotic efficacy. When comparing the different combinations to the control solution, the results of this study signify the presence of synergistic interactions between select essential oils; the combinations that were proven to increase antibacterial efficacy when compared to the control were the tea tree/oregano and tea/tree thyme solution. The combination with the greatest antibacterial efficacy for inhibiting E. coli and S. aureus growth was tea tree and oregano oil, which had an average inhibition percentage of 59.53% (E. coli) and 55.91% (S. aureus). This result was found to be statistically significant (p < 0.05) using an ANOVA single factor test

Influence of the brazing parameters on microstructure, residual stresses and shear strength of diamond-metal joints

The reliability and integrity of diamond cutting tools depend on the properties of diamond-metal joints as created by a brazing process. Block-shaped monocrystalline diamonds were brazed onto a steel substrate (X2CrNiMo 18-14-3), using silver-copper based Cusil-ABA™ (Ag-35wt%Cu-1.75wt%Ti) filler alloy. The experimental procedure includes a thorough microstructural investigation of the filler alloy, the determination of the induced residual stresses by Raman spectroscopy as well as the joint's shear strength utilizing a special shear device. The brazing processes were carried out at 850, 880 and 910°C for dwell durations of 10 and 30min, respectively. At the steel interface two interlayers develop. The layers grow with extended dwell duration and higher brazing temperature. The residual stresses only slightly depend on the brazing parameters and exhibit a maximum value of −400MPa. Unlike the residual stresses, the shear strength strongly depends on the brazing parameters and thus on the microstructure. Three failure modes could be identified; a ductile fracture in the filler alloy, a brittle fracture in the interlayers and a partly shattering of the diamon

Experimental investigation and thermodynamic modeling of the Au-Ge-Ni system

Phase equilibria in the Au-Ge-Ni ternary system were studied by means of scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and differential scanning calorimetry. The phase relations in the solid state at 600°C as well as a vertical section at Au72Ge28-Ni were established. No ternary compound was found at 600°C. On the basis of the experimental phase equilibria data, a thermodynamic model of the Au-Ge-Ni ternary system was developed using the CALPHAD method. Thermodynamically calculated phase diagrams are shown at 600°C, in two vertical sections and the liquidus projection. Reasonable agreement between the calculations and the experimental results was achieved. Graphical abstrac

Implementation of an Educational Workshop on the Use of Evidence-Based Lifestyle Management Programs to Prevent Diabetes

Prediabetes does not have to lead to type 2 diabetes. Lifestyle management programs (LMPs) have been shown to reduce the risk of conversion to type 2 diabetes (Diabetes Prevention Research Group (DPRG), 2002), however, research suggests providers refer to LMPs less than 10% of the time (Shiffman et al., 2009). The purpose of this project was to improve prediabetes management by increasing primary care (PCP) referrals to a local Diabetes Prevention Program (DPP) through the use of an educational intervention to increase knowledge of DPP, prediabetes documentation, and steps for DPP referral. The ACE Star Model of Knowledge Transformation guided project design from discovery of knowledge to integration in clinical practice. Outcome measures included number of DPP referrals and prediabetes ICD 10 codes pre and post-education of PCPs and survey responses on barriers to referral. The Wilcoxon Signed Rank test determined statistical significance in change pre and post educational intervention. DPP referrals increased from zero to four post intervention (p=.157) and ICD-10 codes increased from 41 to 43 in the post intervention group (P=.655). The post intervention survey found cost and lack of insurance coverage to be the most common referral barriers. While there were increases in post intervention referrals and ICD10 codes, the results were not statistically significant. This increase, however, warrants further investigation by means of a larger study. Over 50% of patients met criteria for Medicare (45/84). If certification was sought to become a Medicare DPP provider, DPP could be offered at no cost, alleviating referral barriers

Information reuse of nondestructive evaluation (NDE) data sets

To achieve added value from data spaces and data sets in general, an essential condition is to ensure the high quality of the stored information and its continuous availability. Nondestructive evaluation (NDE) processes represent an information source with potential for reuse. These provide essential information for the evaluation and characterization of materials and components. This information, along with others such as process parameters, is a valuable resource for data-driven added value, e.g., for process optimization or as training data for artificial intelligence (AI) applications. However, this use requires the continuous availability of NDE data sets as well as their structuring and readability. This paper describes the steps necessary to realize an NDE data cycle from the generation of information to the reuse of data.</p

Failure mechanisms and cutting characteristics of brazed single diamond grains

The knowledge about the cutting characteristics and the critical loading of brazed diamonds is essential for a safe and economic application of engineered grinding tools. Scratch tests were performed with single grains. The experiments were conducted with standard polyhedral diamond grains of different sizes, ranging from 300 to 850μm, brazed with an Ag-Cu-based and a Cu-Sn-based active filler alloy onto a steel pin. Two failure mechanisms were revealed, namely "grain pullout” and "grain fracture”. Large grits mainly fail by grain fracture, whereas the smaller ones were mostly pulled out. This trend is supported by a simple mechanical model. The critical values, i.e. cutting force/scratch area, for grain fracture and grain pullout show a decrease with bigger grit size. Scratches are also analysed in terms of cutting characteristics. The dependency of the cutting and the normal force on the scratch area can be described by a power law with powers ranging between about 0.2 and 0.7, respectively. The measured cutting forces strongly depend on the rake angle, which was tested for −19.5° and −35.3

Wetting Behavior of Ternary Au-Ge-X (X=Sb, Sn) Alloys on Cu and Ni

Au-Ge-based alloys are potential substitutes for Pb-rich solders currently used for high-temperature applications. In the present work, the wetting behavior of two Au-Ge-X (X=Sb, Sn) ternary alloys, i.e., Au-15Ge-17Sb and Au-13.7 Ge-15.3Sn (at.%), in contact with Cu and Ni substrates has been investigated. Au-13.7Ge-15.3Sn alloy showed complete wetting on both Cu and Ni substrates. Total spreading of Au-15Ge-17Sb alloy on Cu was also observed, while the final contact angle of this alloy on Ni was about 29°. Pronounced dissolution of Cu substrates into the solder alloys investigated was detected, while the formation of Ni-Ge intermetallic compounds at the interface of both solder/Ni systems suppressed the dissolution of Ni into the solde