Recent Developments in Engineering Measurements Lab

Over the past two years, the Engineering Measurements Lab has attempted to increase the breadth and depth of course material introduced to students to allow them to design and perform successful experimental tests. Over that time, the following structural changes have been made to this course: (i) a single lecture contact hour per week was added, (ii) lab contact hours focus more on practical aspects of each lab, and (iii) the number of experiments run in the course has increased from four to seven. To reflect these changes, the course has grown from one credit to two credits. Material for each lab was delivered in a two-week cycle with a one-hour lecture and two-hour lab period every week. Each lab had one dedicated lecture and additional lectures were added to further emphasize broader topics including data acquisition, measurement uncertainty, and statistical analysis. In addition to the updated course content, the Toyota A3 report format has been adopted for all labs to expose students to a wider variety of tools for technical communication and to foster a spirit of creative and innovative problem solving. In keeping with the iterative nature of these reports, the general process for each lab involves multiple events with feedback from peers and instructors. During the week “A†lab period, students are introduced to the lab facility and perform an ungraded activity where they manually perform relevant calculations using a small subset of previously recorded data. They are then presented with a full set of previous data so they can perform relevant calculations and plot pertinent information. This prelab data exercise is submitted before the week “B†lab period. During the week “B†lab period, students run the laboratory to generate their own data set. A draft A3 report is then submitted prior to the following week “A†lab period. Students peer-review the draft A3 reports in lab before they perform the manual activity for the next laboratory. Final A3 drafts are due at 11:59 pm the following day. Lab topics for this course include characterization of (i) vortex tubes, (ii) vapor compression refrigeration, (iii) centrifugal pumps, and (iv) frictional pipe losses. New labs have been developed for this course examining (v) error propagation in measurement of complex geometries, (vi) measuring Poiseuille flow velocity profiles, and (vii) thermocouple calibration. This work will describe the changes made to this course over the past two years and discuss their suitability based on effectiveness and student satisfaction. Plans for future development of the course will also be discussed

MexEF-OprN Efflux Pump Exports the Pseudomonas Quinolone Signal (PQS) Precursor HHQ (4-hydroxy-2-heptylquinoline)

Bacterial cells have evolved the capacity to communicate between each other via small diffusible chemical signals termed autoinducers. Pseudomonas aeruginosa is an opportunistic pathogen involved, among others, in cystic fibrosis complications. Virulence of P. aeruginosa relies on its ability to produce a number of autoinducers, including 4-hydroxy-2-alkylquinolines (HAQ). In a cell density-dependent manner, accumulated signals induce the expression of multiple targets, especially virulence factors. This phenomenon, called quorum sensing, promotes bacterial capacity to cause disease. Furthermore, P. aeruginosa possesses many multidrug efflux pumps conferring adaptive resistance to antibiotics. Activity of some of these efflux pumps also influences quorum sensing. The present study demonstrates that the MexEF-OprN efflux pump modulates quorum sensing through secretion of a signalling molecule belonging to the HAQ family. Moreover, activation of MexEF-OprN reduces virulence factor expression and swarming motility. Since MexEF-OprN can be activated in infected hosts even in the absence of antibiotic selective pressure, it could promote establishment of chronic infections in the lungs of people suffering from cystic fibrosis, thus diminishing the immune response to virulence factors. Therapeutic drugs that affect multidrug efflux pumps and HAQ-mediated quorum sensing would be valuable tools to shut down bacterial virulence

CD14 Deficiency Impacts Glucose Homeostasis in Mice through Altered Adrenal Tone

The toll-like receptors comprise one of the most conserved components of the innate immune system, signaling the presence of molecules of microbial origin. It has been proposed that signaling through TLR4, which requires CD14 to recognize bacterial lipopolysaccharide (LPS), may generate low-grade inflammation and thereby affect insulin sensitivity and glucose metabolism. To examine the long-term influence of partial innate immune signaling disruption on glucose homeostasis, we analyzed knockout mice deficient in CD14 backcrossed into the diabetes-prone C57BL6 background at 6 or 12 months of age. CD14-ko mice, fed either normal or high-fat diets, displayed significant glucose intolerance compared to wild type controls. They also displayed elevated norepinephrine urinary excretion and increased adrenal medullary volume, as well as an enhanced norepinephrine secretory response to insulin-induced hypoglycemia. These results point out a previously unappreciated crosstalk between innate immune- and sympathoadrenal- systems, which exerts a major long-term effect on glucose homeostasis

Meta-Analysis Comparing Wettability Parameters and the Effect of Wettability on Friction Coefficient in Lubrication

This work presents a meta-analysis that compares the suitability of various parameters used to characterize wettability in tribological systems. It also examines the relationship between wettability and the friction factor for multiple lubricant-surface pairings. The characterization of wetting behavior was similar when using the contact angle between a lubricant and surface and various dimensional and dimensionless formulations of a spreading parameter. It was possible to identify hydrodynamic, boundary, and mixed lubrication regimes by combining a dimensionless wettability parameter with the specific film thickness for a variety of neat ionic liquids and magnetorheological fluids in contact with metallic, thermoplastic, and elastic surfaces. This characterization was possible using multiple dimensionless wettability parameters, but those that can be fully determined using only the contact angle may be preferred by experimentalists. The use of dimensional and dimensionless wettability parameters that included polar and disperse components of surface tension and surface energy did not appear to provide additional insight into the wettability or frictional performance for the tribological system examined here

OBSERVATION OF CONTACT LINE DYNAMICS IN EVAPORATING DROPLETS UNDER THE INFLUENCE OF ELECTRIC FIELDS

ABSTRACT Deposition of colloidal material in evaporating droplets is important in many applications including DNA sequencing and medical diagnostic testing. When colloidal droplets evaporate, the majority of material is often deposited at the periphery of the resultant deposition in a coffee-ring pattern. Formation of this pattern is the result of contact line pinning and the interplay between evaporative and surface tension effects in the droplet. When the contact line is pinned and the evaporative flux in the droplet is highest at the periphery, a radially outward flow is generated to conserve mass that deposits particles in the fluid at the contact line. Evaporation at the contact line can also create a temperature gradient across the droplet. This gradient gives rise to a surface tension driven flow that can resuspend particles in the droplet. When the evaporative flow dominates, particles are deposited at the contact line in a coffee-ring pattern. The presence of the coffee-ring pattern is undesirable in many printing and medical diagnostic processes. Suppression of the coffee-ring effect has been achieved by addition of surfactant, enhancement of surface tension flow, surface modification, alteration of particle shape, and application of an electric field. Manipulation of the coffee-ring effect has been achieved through the application of both AC and DC electric fields