Comprehensive process maps for synthesizing high density aluminum oxide-carbon nanotube coatings by plasma spraying for improved mechanical and wear properties

Plasma sprayed aluminum oxide ceramic coating is widely used due to its outstanding wear, corrosion, and thermal shock resistance. But porosity is the integral feature in the plasma sprayed coating which exponentially degrades its properties. In this study, process maps were developed to obtain Al2O3-CNT composite coatings with the highest density (i.e. lowest porosity) and improved mechanical and wear properties. Process map is defined as a set of relationships that correlates large number of plasma processing parameters to the coating properties. Carbon nanotubes (CNTs) were added as reinforcement to Al2O 3 coating to improve the fracture toughness and wear resistance. Two novel powder processing approaches viz spray drying and chemical vapor growth were adopted to disperse CNTs in Al2O3 powder. The degree of CNT dispersion via chemical vapor deposition (CVD) was superior to spray drying but CVD could not synthesize powder in large amount. Hence optimization of plasma processing parameters and process map development was limited to spray dried Al2O3 powder containing 0, 4 and 8 wt. % CNTs. An empirical model using Pareto diagram was developed to link plasma processing parameters with the porosity of coating. Splat morphology as a function of plasma processing parameter was also studied to understand its effect on mechanical properties. Addition of a mere 1.5 wt. % CNTs via CVD technique showed ∼27% and ∼24% increase in the elastic modulus and fracture toughness respectively. Improved toughness was attributed to combined effect of lower porosity and uniform dispersion of CNTs which promoted the toughening by CNT bridging, crack deflection and strong CNT/Al2O3 interface. Al2O 3-8 wt. % CNT coating synthesized using spray dried powder showed 73% improvement in the fracture toughness when porosity reduced from 4.7% to 3.0%. Wear resistance of all coatings at room and elevated temperatures (573 K, 873 K) showed improvement with CNT addition and decreased porosity. Such behavior was due to improved mechanical properties, protective film formation due to tribochemical reaction, and CNT bridging between the splats. Finally, process maps correlating porosity content, CNT content, mechanical properties, and wear properties were developed.

Factors surgical team members perceive influence choices of wearing or not wearing personal protective equipment during operative /invasive procedures

Exposure to certain bloodborne pathogens can prematurely end a person’s life. Healthcare workers (HCWs), especially those who are members of surgical teams, are at increased risk of exposure to these pathogens. The proper use of personal protective equipment (PPE) during operative/invasive procedures reduces that risk. Despite this, some HCWs fail to consistently use PPE as required by federal regulation, accrediting agencies, hospital policy, and professional association standards. The purpose of this mixed methods survey study was to (a) examine factors surgical team members perceive influence choices of wearing or not wearing PPE during operative/invasive procedures and (b) determine what would influence consistent use of PPE by surgical team members. Using an ex post facto, non-experimental design, the memberships of five professional associations whose members comprise surgical teams were invited to complete a mixed methods survey study. The primary research question for the study was: What differences (perceptual and demographic) exist between surgical team members that influence their choices of wearing or not wearing PPE during operative/invasive procedures? Four principal differences were found between surgical team members. Functional (i.e., profession or role based) differences exist between the groups. Age and experience (i.e., time in profession) differences exist among members of the groups. Finally, being a nurse anesthetist influences the use of risk assessment to determine the level of PPE to use. Four common themes emerged across all groups informing the two study purposes. Those themes were: availability, education, leadership, and performance. Subsidiary research questions examined the influence of previous accidental exposure to blood or body fluids, federal regulations, hospital policy and procedure, leaders’ attitudes, and patients’ needs on the use of PPE. Each of these was found to strongly influence surgical team members and their use of PPE during operative/invasive procedures. Implications based on the findings affect organizational policy, purchasing and distribution decisions, curriculum design and instruction, leader behavior, and finally partnership with PPE manufacturers. Surgical team members must balance their innate need to care for patients with their need to protect themselves. Results of this study will help team members, leaders, and educators achieve this balance.

A heuristic algorithm to generate test program sequences for moving probe electronic test equipment

The electronics industry, is experiencing two trends one of which is the drive towards miniaturization of electronic products. The in-circuit testing predominantly used for continuity testing of printed circuit boards (PCB) can no longer meet the demands of smaller size circuits. This has lead to the development of moving probe testing equipment. Moving Probe Test opens up the opportunity to test PCBs where the test points are on a small pitch (distance between points). However, since the test uses probes that move sequentially to perform the test, the total test time is much greater than traditional in-circuit test. While significant effort has concentrated on the equipment design and development, little work has examined algorithms for efficient test sequencing. The test sequence has the greatest impact on total test time, which will determine the production cycle time of the product. Minimizing total test time is a NP-hard problem similar to the traveling salesman problem, except with two traveling salesmen that must coordinate their movements. The main goal of this thesis was to develop a heuristic algorithm to minimize the Flying Probe test time and evaluate the algorithm against a "Nearest Neighbor" algorithm. The algorithm was implemented with Visual Basic and MS Access database. The algorithm was evaluated with actual PCB test data taken from Industry. A statistical analysis with 95% C.C. was performed to test the hypothesis that the proposed algorithm finds a sequence which has a total test time less than the total test time found by the "Nearest Neighbor" approach. Findings demonstrated that the proposed heuristic algorithm reduces the total test time of the test and, therefore, production cycle time can be reduced through proper sequencing.

Factors Surgical Team Members Perceive Influence Choices of Wearing or not Wearing Personal Protective Equipment During Operative/Invasive Procedures

Exposure to certain bloodborne pathogens can prematurely end a person’s life. Healthcare workers (HCWs), especially those who are members of surgical teams, are at increased risk of exposure to these pathogens. The proper use of personal protective equipment (PPE) during operative/invasive procedures reduces that risk. Despite this, some HCWs fail to consistently use PPE as required by federal regulation, accrediting agencies, hospital policy, and professional association standards. The purpose of this mixed methods survey study was to (a) examine factors surgical team members perceive influence choices of wearing or not wearing PPE during operative/invasive procedures and (b) determine what would influence consistent use of PPE by surgical team members. Using an ex post facto, non-experimental design, the memberships of five professional associations whose members comprise surgical teams were invited to complete a mixed methods survey study. The primary research question for the study was: What differences (perceptual and demographic) exist between surgical team members that influence their choices of wearing or not wearing PPE during operative/invasive procedures? Four principal differences were found between surgical team members. Functional (i.e., profession or role based) differences exist between the groups. Age and experience (i.e., time in profession) differences exist among members of the groups. Finally, being a nurse anesthetist influences the use of risk assessment to determine the level of PPE to use. Four common themes emerged across all groups informing the two study purposes. Those themes were: availability, education, leadership, and performance. Subsidiary research questions examined the influence of previous accidental exposure to blood or body fluids, federal regulations, hospital policy and procedure, leaders’ attitudes, and patients’ needs on the use of PPE. Each of these was found to strongly influence surgical team members and their use of PPE during operative/invasive procedures. Implications based on the findings affect organizational policy, purchasing and distribution decisions, curriculum design and instruction, leader behavior, and finally partnership with PPE manufacturers. Surgical team members must balance their innate need to care for patients with their need to protect themselves. Results of this study will help team members, leaders, and educators achieve this balance.