ELECTROKINETIC PARTICLE MANIPULATIONS IN SPIRAL MICROCHANNELS

Recent developments in the field of microfluidics have created a multitude of new useful techniques for practical particle and cellular assays. Among them is the use of dielectrophoretic forces in \u27lab-on-a-chip\u27 devices. This sub-domain of electrokinetic flow is particularly popular due to its advantages in simplicity and versatility. This thesis makes use of dielectrophoretic particle manipulations in three distinct spiral microchannels. In the first of these experiments, we demonstrate the utility of a novel single-spiral curved microchannel with a single inlet reservoir and a single outlet reservoir for the continuous focusing and filtration of particles. The insulator-based negative-dielectrophoretic (repulsive) force is used in a parametric study of the effects of electric field strength, particle size, and solution concentration on particle focusing abilities. It was summarily determined that all three factors are positively correlated with increased particle focusing ability. From these results, a partial filtration of 10 μm particles from a binary solution of 3 and 10 μm particles was demonstrated. Also observed was a balance between dielectrophoretic and repulsive particle-wall interactions; thus yielding a novel approach for particle manipulation. Following the results of the first, we demonstrate in the second experiment a continuous-flow electrokinetic separation of both a binary mixture and a ternary mixture of colloidal particles based on size in a single-spiral microchannel with a single inlet reservoir and triple outlet reservoirs. This method also utilizes both curvature-induced dielectrophoresis to focus particles to a tight stream and the previously observed wall-induced electric lift to manipulate the aligned particles to size-dependent equilibrium positions. Due to the continuous nature of the flow through concentric spiral loops, both focusing forces influence particles simultaneously. This novel technique is useful for its compact geometry, robust structure, ease of manufacture, and ease of use in the manipulation of independent particle species. A theoretical model is also developed to understand this separation, and the obtained analytical formula predicts the experimentally measured particle center-wall distance in the spiral with a close agreement. We demonstrate in the third experiment a continuous-flow electrical sorting of spherical and peanut-shaped particles of similar volumes in an asymmetric double-spiral microchannel with a single inlet reservoir and triple outlet reservoirs. This experiment, unlike the first two, differentiates particle species based principally on shape. Shape is an intrinsic marker of cell cycle, an important factor for identifying a bio-particle, and also a useful indicator of cell state for disease diagnostics; therefore, shape can be a specific marker in label-free particle and cell separation for various chemical and biological applications. The double-spiral geometry exploits curvature-induced dielectrophoresis to initially focus particles to a tight stream in the first spiral without any sheath flow. Particles are subsequently displaced to shape-dependent flow paths in the second spiral without any external force. We also develop a numerical model to simulate and understand this shape-based particle sorting in spiral microchannels. The predicted particle trajectories agree qualitatively with the experimental observation

Fostering Peer Evaluation Skills in Nursing Students

Nursing peer review is a professional practice in which nurses offer constructive, non-personal, practice-related feedback to fellow nurses. The use of nursing peer review has been recommended by the American Nurses Association (ANA 1988, 2014) and the American Nurses Credentialing Center (ANCC 2008). Despite being recommended by professional organizations, the use of peer review in nursing has not been widely implemented. Evaluation of nursing colleagues has the potential to enhance professional nursing, both in practice and in nursing education. Fostering the skills needed to provide peers with evaluative feedback might best be accomplished if the process is started during nursing school. Teaching ways in which to give and receive feedback without causing feelings of conflict could normalize the process for future generations of nurses. The purpose of this quantitative, quasi-experimental, descriptive study was to examine the impact of teaching nursing peer review skills to student nurses. Based on results, lessons on providing constructive peer feedback will be incorporated into future semesters in a Bachelor of Science in Nursing (BSN) program at a state university in Arkansas

Effect of Alfalfa Meal and Brewers Dried Yeast on Digestibility of Different Qualities of Prairie Hay by Cattle and Sheep

Roughages are one of the most important feeding stuffs, and a large quantity is produced each year that has a little market value except as a feed for ruminants. Cattle and sheep are able to consume and utilize efficiently large quantities of roughages when they are supplied with an adequate amount of nutrients essential for the animal and for an active bacterial population in the rumen. However, roughages vary considerably in their nutrient content and, thus, in their value as a feed, depending upon many factors, some of which are discussed in the review of literature. It is important that the farmer and rancher know the factors affecting the nutritive value of roughages so that they can produce the best quality possible and can better understand how to supplement them to get the most feeding value therefrom. Methods of improving the digestibility of roughages by various supplements have received considerable attention by research workers. This research has brought about a concept that to feed ruminants properly on roughages, especially poor quality roughages, supplements must be provided which will contain essential nutrients to fulfill the nutritional requirements of rumen microorganisms. An active rumen flora is necessary to break down the resistant nutrients in roughages into a usable form. The work reported herein supplements on the digestibility of both early and late-cut prairie hay. This is the most important roughage fed to cattle and sheep during the winter months in this area. The supplements used in the work reported were alfalfa meal and brewers dried yeast, both of which have received prominence in supplementing poor quality roughages. Both cattle and sheep were used in the experiment to determine their comparative digestive powers with these hays of different quality and with the two supplements at various levels

Geochemical Signatures of Stream Capture in the Retreating Blue Ridge Escarpment, Southern Appalachian Mountains

Stream capture is a major driver of the retreat of the Blue Ridge Escarpment, but timescales of capture are not well understood. This study examines stream sediment geochemistry to establish a set of sediment source fingerprints which can be used to identify and date the capture of the Tallulah River. Statistical analyses show significant differences in U, Th, and certain REE enrichment. These differences result from variations in bedrock along the lengths of each river and a shift in relative stream powers after capture to favor mobilization or deposition of heavy elements. The observed differences should be sufficient to identify where Tallulah sediment appears in floodplains of the capturing Tugaloo River, facilitating future dating of the capture event. Understanding the timing of river capture will provide insight into the ongoing reshaping and redistribution of river systems and interactions of geomorphic processes in the continuing evolution of the southern Appalachian Mountains

Standards for Appellate Conduct Adopted in Texas

Texas is the first state to adopt standards of conduct for appellate advocates. This article examines the reason for, content of, along with the limitations and benefits of Texas’s Standards for Appellate Conduct

WHAT ATTRACTS OLDER NURSES TO ORGANIZATIONS? PSYCHOLOGICAL MODERATORS OF THE IMPACT OF FLEXIBLE SCHEDULING AND MENTORING OPPORTUNITIES

The current study investigated two psychological moderators (generativity and occupational stress) of the impact of flexible scheduling and mentoring opportunities on the attraction and application intentions of older nurses of bridge employment age. Of the 600 registered nurses who were contacted via postal mail, 101 responded. Participants were randomly assigned to one of six conditions in which a hypothetical job advertisement was manipulated with varying levels each of flexible scheduling (input vs no input into the schedule) and mentoring opportunities (formal, informal, and none). Input was found to have a main effect on organizational attraction, but main effects were not found for mentoring opportunities. No moderation effects were found. Interestingly, generativity was found to have a main effect on both organizational and application intentions, indicating its importance in future research of the interest to return to work of bridge employees

Promoting Equality and Access in Higher Education: A Comparative Study of State Sponsored Preferential Policies in Great Britain, India and South Africa

Recent U.S. court decisions striking down affirmative action policies in college admissions have caused universities to seek diversity programs that can hold up to public and Jesa1 scrutiny while maintaining diversity on campus. The purpose of this thesis is to study the preference programs of other countries and determine if successful elements could be duplicated here in the United States. Specifically, the study looks at whether countries who use equality of opportunity programs (which focus on training initiatives) are more successful in increasing enrollment and hiring numbers of minorities than equality of outcome measures (which focus on quotas). The study also asked the larger theoretical question of whether preference programs are successful in distributing valuable higher education resources to minorities

Promoting Equality and Access in Higher Education: A Comparative Study of State Sponsored Preferential Policies in Great Britain, India and South Africa

Recent U.S. court decisions striking down affirmative action policies in college admissions have caused universities to seek diversity programs that can hold up to public and Jesa1 scrutiny while maintaining diversity on campus. The purpose of this thesis is to study the preference programs of other countries and determine if successful elements could be duplicated here in the United States. Specifically, the study looks at whether countries who use equality of opportunity programs (which focus on training initiatives) are more successful in increasing enrollment and hiring numbers of minorities than equality of outcome measures (which focus on quotas). The study also asked the larger theoretical question of whether preference programs are successful in distributing valuable higher education resources to minorities