Browsing by Author "Zhou, J"

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    Chemical and biological applications of digital-microfluidic devices
    (IEEE Design and Test of Computers, 2007-01-01) Fair, RB; Khlystov, A; Tailor, TD; Ivanov, V; Evans, RD; Srinivasan, V; Pamula, VK; Pollack, MG; Griffin, PB; Zhou, J
    The advent of digital microfluidic lab-on-a-chip (LoC) technology offers a platform for developing diagnostic applications with the advantages of portability, reduction of the volumes of the sample and reagents, faster analysis times, increased automation, low power consumption, compatibility with mass manufacturing, and high throughput. Moreover, digital microfluidics is being applied in other areas such as airborne chemical detection, DNA sequencing by synthesis, and tissue engineering. In most diagnostic and chemical-detection applications, a key challenge is the preparation of the analyte for presentation to the on-chip detection system. Thus, in diagnostics, raw physiological samples must be introduced onto the chip and then further processed by lysing blood cells and extracting DNA. For massively parallel DNA sequencing, sample preparation can be performed off chip, but the synthesis steps must be performed in a sequential on-chip format by automated control of buffers and nucleotides to extend the read lengths of DNA fragments. In airborne particulate-sampling applications, the sample collection from an air stream must be integrated into the LoC analytical component, which requires a collection droplet to scan an exposed impacted surface after its introduction into a closed analytical section. Finally, in tissue-engineering applications, the challenge for LoC technology is to build high-resolution (less than 10 microns) 3D tissue constructs with embedded cells and growth factors by manipulating and maintaining live cells in the chip platform. This article discusses these applications and their implementation in digital-microfluidic LoC platforms. © 2007 IEEE.
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    On enrichment strategies for biomarker stratified clinical trials
    (Journal of Biopharmaceutical Statistics, 2017-09-07) Wang, X; Zhou, J; Wang, T; George, SL
    In the era of precision medicine, drugs are increasingly developed to target subgroups of patients with certain biomarkers. In large all-comer trials using a biomarker strati ed design (BSD), the cost of treating and following patients for clinical outcomes may be prohibitive. With a fixed number of randomized patients, the efficiency of testing certain treatments parameters, including the treatment effect among biomarker positive patients and the interaction between treatment and biomarker, can be improved by increasing the proportion of biomarker positives on study, especially when the prevalence rate of biomarker positives is low in the underlying patient population. When the cost of assessing the true biomarker is prohibitive, one can further improve the study efficiency by oversampling biomarker positives with a cheaper auxiliary variable or a surrogate biomarker that correlates with the true biomarker. To improve efficiency and reduce cost, we can adopt an enrichment strategy for both scenarios by concentrating on testing and treating patient subgroups that contain more information about specifi c treatment parameters of primary interest to the investigators. In the first scenario, an enriched biomarker strati ed design (EBSD) enriches the cohort of randomized patients by directly oversampling the relevant patients with the true biomarker, while in the second scenario, an auxiliary-variable-enriched biomarker strati ed design (AEBSD) enriches the randomized cohort based on an inexpensive auxiliary variable, thereby avoiding testing the true biomarker on all screened patients and reducing treatment waiting time. For both designs, we discuss how to choose the optimal enrichment proportion when testing a single hypothesis or two hypotheses simultaneously. At a requisite power, we compare the two new designs with the BSD design in term of the number of randomized patients and the cost of trial under scenarios mimicking real biomarker strati ed trials. The new designs are illustrated with hypothetical examples for designing biomarker-driven cancer trials.
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    Preclinical characterization of DUOC-01, a candidate cell therapy product derived from human banked umbilical cord blood intended for use in treatment of demyelinating diseases
    (Cytotherapy, 2014-04) Kurtzberg, J; Buntz, S; Gentry, T; Storms, R; Wenger, DA; Noldner, P; Zhou, J; Ozamiz, A; Rusche, B; Balber, A
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    Tissue distribution of a cord blood-derived cell product following intrathecal transplantation
    (Cytotherapy, 2014-04) Storms, R; Liu, C; Gentry, T; Zhou, J; Ozamiz, A; Rusche, B; Balber, A; Kurtzberg, J
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    Weak coupling of pseudoacoustic phonons and magnon dynamics in the incommensurate spin-ladder compound S r14 C u24 O41
    (Physical Review B - Condensed Matter and Materials Physics, 2016-10-21) Chen, X; Bansal, D; Sullivan, S; Abernathy, DL; Aczel, AA; Zhou, J; Delaire, O; Shi, L
    © 2016 American Physical Society.Intriguing lattice dynamics have been predicted for aperiodic crystals that contain incommensurate substructures. Here we report inelastic neutron scattering measurements of phonon and magnon dispersions in Sr14Cu24O41, which contains incommensurate one-dimensional (1D) chain and two-dimensional (2D) ladder substructures. Two distinct pseudoacoustic phonon modes, corresponding to the sliding motion of one sublattice against the other, are observed for atomic motions polarized along the incommensurate axis. In the long wavelength limit, it is found that the sliding mode shows a remarkably small energy gap of 1.7-1.9 meV, indicating very weak interactions between the two incommensurate sublattices. The measurements also reveal a gapped and steep linear magnon dispersion of the ladder sublattice. The high group velocity of this magnon branch and weak coupling with acoustic and pseudoacoustic phonons can explain the large magnon thermal conductivity in Sr14Cu24O41 crystals. In addition, the magnon specific heat is determined from the measured total specific heat and phonon density of states and exhibits a Schottky anomaly due to gapped magnon modes of the spin chains. These findings offer new insights into the phonon and magnon dynamics and thermal transport properties of incommensurate magnetic crystals that contain low-dimensional substructures.