Microfluidic concentration of bacteria by on-chip electrophoresis

In this contribution, we present a system for efficient preconcentration of pathogens without affecting their viability. Development of miniaturized molecular diagnostic kits requires concentration of the sample, molecule extraction, amplification, and detection. In consequence of low analyte concentrations in real-world samples, preconcentration is a critical step within this workflow. Bacteria and viruses exhibit a negative surface charge and thus can be electrophoretically captured from a continuous flow. The concept of phaseguides was applied to define gel membranes, which enable effective and reversible collection of the target species. E. coli of the strains XL1-blue and K12 were used to evaluate the performance of the device. By suppression of the electroosmotic flow both strains were captured with efficiencies of up to 99%. At a continuous flow of 15 μl/min concentration factors of 50.17 ± 2.23 and 47.36 ± 1.72 were achieved in less than 27 min for XL1-blue and K12, respectively. These results indicate that free flow electrophoresis enables efficient concentration of bacteria and the presented device can contribute to rapid analyses of swab-derived samples.     

Symmetry properties of tetraammine platinum（Ⅱ） with C2v and C4v point groups

Let G be a weighted graph with adjacency matrix A=[aij]. An Euclidean graph associated with a molecule is defined by a weighted graph with adjacency matrix D=[d/ij], where for i≠j, dij is the Euclidean distance between the nuclei i and j. In this matrix dij can be taken as zero if all the nuclei are equivalent. Otherwise, one may introduce different weights for different nuclei.Balasubramanian (1995) computed the Euclidean graphs and their automorphism groups for benzene, eclipsed and staggered forms of ethane and eclipsed and staggered forms of ferroeene. This paper describes a simple method, by means of which it is possible to calculate the automorphism group of weighted graphs. We apply this method to compute the symmetry of tetraammine platinum(Ⅱ) with C2v and C4v point groups.     

The career planning, athletic identity, and student role identity of intercollegiate student athletes

The purpose of this study was to examine the career planning of university student athletes and relationships between their career planning and athletic and student role identities. Two retrospective in-depth interviews were held with four male and four female university student athletes. Participants entered university with vague or nonexistent career objectives and invested heavily in their athletic roles. In the latter years of their college career, the participants discarded their sport career ambitions and allowed the student role to become more prominent in their identity hierarchies. The current findings support Brown and Hartley's (1998) suggestion that student athletes may invest in both the athlete and student role identities simultaneously and that investing in the latter may permit the exploration of nonsport career options.