Thrust and torque response for drilling titanium and carbon composite sandwich materials [abstract]

Abstract only availableExperiments were conducted based upon previous research conducted by El-Gizawy and Khasawneh [1] to determine the time response of thrust force and torque correlated to a simple drilling procedure through carbon fiber reinforced epoxy (IM7/997-3) composite material over 6Al-4V titanium alloy (AB1) sheets. The experiments measured the time response with a thrust and torque sensor, data acquisition system and CNC drilling machine. The research was used to locate points of interest among the previous statistical setup. Three-dimensional surfaces were analyzed to determine the drilling parameters that cause the highest force and torque in the CNC spindle (and, therefore, the drill bit) and the lowest force and torque, within the range available with the CNC used in the experimental setup. The experimental holes were also analyzed via surface profilometer and coordinate measurement probe to obtain surface roughness and dimensional accuracy measurements. The data indicates that the parameters that cause lower force and torque are preferable for dimensional accuracy in the titanium as well as for surface roughness, and tool life.College of Engineering Undergraduate Research Optio

Design of an electrical system for swaging targets in the production of molybdenum-99 [abstract]

Abstract only availableMolybdenum-99 is used all over the world to make technetium-99m for use in medical and research fields. The Molybdenum-99 is made by placing low enriched uranium foil in a reactor and allowing it to be irradiated. In order to irradiate the uranium safely, an aluminum target must be assembled to surround the foil. The current process for making these targets is to use a manually powered swaging device. It works by pulling a plug through an aluminum tube assembly which contains the uranium foil. The plug plastically deforms the inner tube and seals the foil inside. This process is time consuming and requires a lot of strength. The idea of using an electrically driven system to swag the tubes was investigated. The required system was analyzed to determine the forces, torque and power needed. A detailed design of the driving system was established and necessary standard components were selected. The new design concept was constructed in a three dimensional solid presentation and in two dimensional drawings. Assembly analysis of different components was conducted in order to assure accurate mating relations among different components

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

Background End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

DETC2005-84399 DEVELOPMENT OF VIRTUAL FLOW MODEL FOR PROCESS DESIGN IN VACUUM ASSISTED RESIN INFUSION MOLDING OPERATIONS

ABSTRACT A virtual flow model for process design in vacuum assisted resin infusion operations is developed. It uses a control volume technique based on finite difference method to characterize flow behavior during resin infusion in molding woven fiber composite structures. In order to enhance the visual capability of the developed virtual model, a geometric reconstruction scheme is used to present the resin flow front at fixed time increment. The Graphic Interchange Format (GIF) is used to combine images into a single file to create animation. This model provides capabilities for prediction of flow pattern, pressure distribution inside the mold, and evolved defects. Several case studies were conducted to evaluate the effectiveness of the developed model

Target test tube assembly process and design for the development of molybdenum-99 [abstract]

Abstract only availableMolybdenum-99 (Mo-99) is used to create Tc-99, a widely used nuclear medicine diagnostic imaging radioisotope. In an attempt to decrease the need for imported Mo-99, development of mechanical systems to efficiently prepare low enriched uranium (LEU) sheets for radiation is needed. Once prepared, the LEU is radiated to create the Mo-99. This process involves layering the LEU foil between two aluminum tubes, swaging the tubes together, and then sealing the ends. The current design, a die and nut/bolt drawn punch swaging system, and using Tig welding to seal the ends is inefficient and inconsistent. The new mechanical system for the swaging process is designed to be efficient and eliminate any inconsistency. Detailed design of the proposed hydraulic concept was established using 3-D solid modeling software (Pro-Engineer) with 2-D views of non standard parts for future construction. The designed assembly was analyzed for accuracy and proper fits and the entire systems swaging operation was virtually simulated to check for potential errors. The required swaging force was determined through analytical analysis process and initial test measurements. Adequate cylinder, pump, and pressure gauge sizes were determined to exceed the minimum required swaging force. By using a horizontally mounted hydraulic jack to swage the tubes, the applied pressure will be monitored using a pressure gauge to insure a steady swaging force. This design utilizes a sliding die with removable end cap to ease the removal of the swaged tubes. This feature also assists in maintenance and the removal of jammed parts. Using an electron microscope, a gap between the swaged tubes was found using the current punch design. After extensive calculations, a new punch was designed to prevent any unwanted spring back induced gap in the aluminum. To reduce the inconsistency in the tube sealing process, concepts in cold rolling are being further studied

Modeling friction stir welding of Al 2024-T3 [abstract]

Abstract only availableFriction stir welding (FSW) is a modification of the traditional friction welding. It is a process patented by The Welding Institute in Cambridge, England in 1991. It is a mechanical process whereby solid-state welding is performed using heat generated from the friction of a rotating tool. Two plates of metal are butted together and held in place against a backing material using a clamping system. The rotating tool is then slowly plunged with a downward force into the weld joint. It remains stationary for a few seconds while enough heat is generated due to friction that the welded material will begin to flow around the tool. Once this point is reached, the tool is traversed along the joint forming the weld behind the tool as it moves along. The main benefits of friction stir welding come from the fact that the melting temperature of the work piece is not reached during the weld. The mechanical properties of welded metals are retained and even improved when the correct welding parameters are utilized—an area of valuable research as FSW is a relatively new process. By varying the downward plunge force, the depth of the penetration of the tool, the rotation speed of the tool, and the linear velocity at which the tool traverses the joint in the welding process, the optimum mechanical properties of the resulting weld can be obtained. This research is concerned with modeling the temperature distribution in the work piece materials during the weld using analytical methods, based on fluid dynamics method. (GAMBIT/FLUENT). A model of the work piece and tool is created and the calculated amount of heat generated by the friction of the tool is applied to this model. It is important to understand the temperature distribution of the welding process because it directly determines the resulting mechanical properties of the weld. This temperature distribution model is compared to actual experimental data and will help to determine the optimum weld parameters.College of Engineering Undergraduate Research Optio