Numerical simulation on the opto-electro-kinetic patterning for rapid concentration of particles in a microchannel

This paper presents a mathematical model for laser-induced rapid electro-kinetic patterning (REP) to elucidate the mechanism for concentrating particles in a microchannel non-destructively and non-invasively. COMSOL^®(v4.2a) multiphysics software was used to examine the effect of a variety of parameters on the focusing performance of the REP. A mathematical model of the REP was developed based on the AC electrothermal flow (ACET) equations, the dielectrophoresis (DEP) equation, the energy balance equation, the Navier-Stokes equation, and the concentration-distribution equation. The medium was assumed to be a diluted solute, and different electric potentials and laser illumination were applied to the desired place. Gold (Au) electrodes were used at the top and bottom of a microchannel. For model validation, the simulation results were compared with the experimental data. The results revealed the formation of a toroidal microvortex via the ACET effect, which was generated due to laser illumination and joule-heating in the area of interest. In addition, under some conditions, such as the frequency of AC, the DEP velocity, and the particle size, the ACET force enhances and compresses resulting in the concentration of particles. The conditions of the DEP velocity and the ACET velocity are presented in detail with a comparison of the experimental results.     

Collagen-based brain microvasculature model in vitro using three-dimensional printed template

We present an engineered three-dimensional (3D) in vitro brain microvasculature system embedded within the bulk of a collagen matrix. To create a hydrogel template for the functional brain microvascular structure, we fabricated an array of microchannels made of collagen I using microneedles and a 3D printed frame. By culturing mouse brain endothelial cells (bEnd.3) on the luminal surface of cylindrical collagen microchannels, we reconstructed an array of brain microvasculature in vitro with circular cross-sections. We characterized the barrier function of our brain microvasculature by measuring transendothelial permeability of 40 kDa fluorescein isothiocyanate-dextran (Stoke''s radius of ∼4.5 nm), based on an analytical model. The transendothelial permeability decreased significantly over 3 weeks of culture. We also present the disruption of the barrier function with a hyperosmotic mannitol as well as a subsequent recovery over 4 days. Our brain microvasculature model in vitro, consisting of system-in-hydrogel combined with the widely emerging 3D printing technique, can serve as a useful tool not only for fundamental studies associated with blood-brain barrier in physiological and pathological settings but also for pharmaceutical applications.     

Hybrid capillary-inserted microfluidic device for sheathless particle focusing and separation in viscoelastic flow

A novel microfluidic device which consists of two stages for particle focusing and separation using a viscoelastic fluid has been developed. A circular capillary tube was used for three-dimensional particle pre-alignment before the separation process, which was inserted in a polydimethylsiloxane microchannel. Particles with diameters of 5 and 10 μm were focused at the centerline in the capillary tube, and the location of particles was initialized at the first bifurcation. Then, 5 and 10 μm particles were successfully separated in the expansion region based on size-dependent lateral migration, with ∼99% separation efficiency. The proposed device was further applied to separation of MCF-7 cells from leukocytes. Based on the cell size distribution, an approximate size cutoff for separation was determined to be 16 μm. At 200 μl/min, 94% of MCF-7 cells were separated with the purity of ∼97%. According to the trypan blue exclusion assay, high viability (∼90%) could be achieved for the separated MCF-7 cells. The use of a commercially available capillary tube enables the device to be highly versatile in dealing with particles in a wide size range by using capillary tubes with different inner diameters.     

The impact of data reduction on the intra-trial reliability of a typical measure of lower limb musculoskeletal stiffness

Double-leg repeated jumping tasks are commonly used as measures of lower limb stiffness in exercise science research. Within similar stiffness calculations, variation in data-reduction criteria exists. The impact of these varied data-reduction methods on stiffness measures is unknown. Sixteen adolescent female participants from varied physical activity backgrounds performed 15 self-paced, bent-knee continuous jumps (CJb) on two force plates. Leg stiffness was calculated as the ratio of the peak force and the centre of mass displacement for each contact. Using combinations of criteria based on previous literature, 83 data-reduction methods were applied to the raw data. Data reduction suitability was assessed based on intra-trial reliability, the number of participants excluded and the average contacts excluded. Four data-reduction methods were deemed suitable for use with adolescent female populations, with three consecutive contacts within 1 SD of the average jump frequency considered optimal. The average individual stiffness values were not greatly influenced by the data-reduction method; however, for a single participant, a stiffness change of up to 6 kN · m^?1 (30%) was observed. The role and potential impact of data-reduction methods used to evaluate measures of lower limb stiffness during repeated jumping tasks warrants consideration.     

Using Six Sigma and Lean in the Library

Businesses have long relied on a variety of strategies to improve quality, efficiency, and service. Some ideas that have persisted over time are Six Sigma and Lean. While Six Sigma, originally intended for manufacturing, focuses on quality and Lean mainly addresses waste, many of the tools and principles involved can also apply to libraries. This article will review the literature on Lean and Six Sigma as they are used in business and then as they have been used in libraries. The resulting discussion will cover how the principles can be applied to better connect with stakeholders by mapping processes and discovering what is value added (VA) versus nonvalue added (NVA), anticipating failure modes using the failure mode and effects analysis (FMEA) framework, and implementing control plans to maintain quality processes and service.     

Interactive Kiosk at the Texas Tech University Libraries

The academic library, given its often privileged position on campus, is the information source that can include directional as well as general campus facts among the myriad of print and e-resources for reference. Also, an academic library's audiences can be quite varied and include prospective students or parents seeking more general knowledge of the building and the campus. Many times this need for information drives patrons to the library service desks. Sometimes, especially during the high-demand seasons of new student orientation and beginning of the fall semesters, the desk is so busy that many patrons will leave because they don't have the time to wait. To address this immediate need for information, Texas Tech University Libraries developed an interactive kiosk to provide general information for frequently asked questions in a more efficient, creative, and interactive way. The kiosk provides a fun method of satisfying a patron's information needs without the requirement of a staff member or the need to wait in line for help. The kiosk is available as long as the Library is open and provides a variety of useful answers to general questions, as well as facts about the Library.     

The Jazz Archives Fellowship: Professional Development and Diversity at the Institute of Jazz Studies

The Institute of Jazz Studies (IJS) started the Jazz Archives Fellows program in 2012 with two purposes in mind. First, the program focuses on improving diversity in the archives profession. Second, it provides a meaningful professional development opportunity for archivists in the early stages of their careers and for students in graduate programs who intend to become archivists. In addition, the IJS benefits directly from the fellows' work to process a collection and create a digital project. This article presents a case study of the Fellowship with a focus on program design, values, and lessons learned and includes recommendations for establishing similar programs.     

How liberals and conservatives respond to feasibility and desirability appeals in anti-tobacco campaigns

Using two experiments, this study aims to investigate how politically liberal or conservative message recipients respond to anti-tobacco appeals. The results show that in Study 1, respondents were exposed to a message about price policy. In Study 2, they were exposed to a message about a warning policy. In both studies, liberal participants more favorably evaluated anti-tobacco messages emphasizing feasibility rather than desirability, whereas conservative participants more positively evaluated messages emphasizing desirability rather than feasibility. Implications for policymakers and marketers are discussed.     

What Motivates Parents to Mediate Children’s Use of Smartphones? An Application of the Theory of Planned Behavior

Applying the Theory of Planned Behavior (TPB), this study examines parents’ attitudes, social norms, self-efficacy, and intentions regarding parental mediation of children’s smartphone use. A survey conducted with parents of young smartphone users aged 10–17 shows that parents tend to perceive discussion-based active mediation to be more desirable, as compared to rule-making restrictive mediation. Findings also indicate that the extent to which parents believe that they have control over their parental mediation practices plays an important role in forming positive intentions to practice parental mediation, regardless of the mediation domain.