Browsing by Author "Li, Z"

Now showing 1 - 13 of 13

Open Access
A Modular Multilevel Series/Parallel Converter for a Wide Frequency Range Operation
(IEEE Transactions on Power Electronics, 2019-10-01) Li, Z; Ricardo Lizana, F; Yu, Z; Sha, S; Peterchev, AV; Goetz, SM
When providing ac output, modular multilevel converters (MMCs) experience power fluctuation in the phase arms. The power fluctuation causes voltage ripple on the module capacitors, which grows with the output power and inversely to the output frequency. Thus, low-frequency operations of MMCs, e.g., for motor drives, require injecting common-mode voltages and circulating currents, and strict dc voltage output relative to ground is impossible. To address this problem, this paper introduces a novel module topology that allows parallel module connectivity in addition to the series and bypass states. The parallel state directly transfers power across the modules and arms to cancel the power fluctuations and hence suppresses the capacitor voltage ripple. The proposed series/parallel converter can operate at a wide frequency range down to dc without common-mode voltages or circulating currents; it also allows sensorless operation and full utilization of the components at higher output frequencies. We present detailed simulation and experiment results to characterize the advantages and limitations of the proposed solution.
Open Access
A Reduced Series/Parallel Module for Cascade Multilevel Static Compensators Supporting Sensorless Balancing
(IEEE Transactions on Industrial Electronics, 2020) Li, Z; Motwani, JK; Zeng, Z; Lukic, SM; Peterchev, AV; Goetz, SM
Open Access
Bispecific Antibody Therapy for Effective Cardiac Repair through Redirection of Endogenous Stem Cells
(Advanced Therapeutics, 2019-10-01) Huang, K; Li, Z; Su, T; Shen, D; Hu, S; Cheng, K
Bone marrow stem cells (BMSCs) are a promising strategy for cardiac regenerative therapy for myocardial infarction (MI). However, cell transplantation has to overcome a number of hurdles, such as cell quality control, clinical practicality, low cell retention/engraftment, and immune reactions when allogeneic cells are used. Bispecific antibodies (BsAbs) have been developed as potential agents in cancer immunotherapy but their application is sparse in cardiovascular diseases. In the present study, BsAbs are designed by chemical cycloaddition of F(ab′)2 fragments from monoclonal anti-CD34 and anti- cardiac myosin heavy chain (CMHC) antibodies, which specifically targets circulating CD34-positive cells and injured cardiomyocytes simultaneously. It is hypothesized that intravenous administration of stem cell re-directing (SCRD) BsAbs (anti-CD34-F(ab′)2–anti-CMHC-F(ab′)2) can home endogenous BMSCs to the injured heart for cardiac repair. The in vivo studies in a mouse model with heart ischemia/reperfusion (I/R) injury demonstrate the safety and therapeutic potency of SCRD BsAb, which supports cardiac recovery by reducing scarring, promoting angiomyogenesis, and boosting cardiac function.
Restricted
c-Myc is required for maintenance of glioma cancer stem cells.
(PLoS One, 2008) Wang, J; Wang, H; Li, Z; Wu, Q; Lathia, JD; McLendon, RE; Hjelmeland, AB; Rich, JN
BACKGROUND: Malignant gliomas rank among the most lethal cancers. Gliomas display a striking cellular heterogeneity with a hierarchy of differentiation states. Recent studies support the existence of cancer stem cells in gliomas that are functionally defined by their capacity for extensive self-renewal and formation of secondary tumors that phenocopy the original tumors. As the c-Myc oncoprotein has recognized roles in normal stem cell biology, we hypothesized that c-Myc may contribute to cancer stem cell biology as these cells share characteristics with normal stem cells. METHODOLOGY/PRINCIPAL FINDINGS: Based on previous methods that we and others have employed, tumor cell populations were enriched or depleted for cancer stem cells using the stem cell marker CD133 (Prominin-1). We characterized c-Myc expression in matched tumor cell populations using real time PCR, immunoblotting, immunofluorescence and flow cytometry. Here we report that c-Myc is highly expressed in glioma cancer stem cells relative to non-stem glioma cells. To interrogate the significance of c-Myc expression in glioma cancer stem cells, we targeted its expression using lentivirally transduced short hairpin RNA (shRNA). Knockdown of c-Myc in glioma cancer stem cells reduced proliferation with concomitant cell cycle arrest in the G(0)/G(1) phase and increased apoptosis. Non-stem glioma cells displayed limited dependence on c-Myc expression for survival and proliferation. Further, glioma cancer stem cells with decreased c-Myc levels failed to form neurospheres in vitro or tumors when xenotransplanted into the brains of immunocompromised mice. CONCLUSIONS/SIGNIFICANCE: These findings support a central role of c-Myc in regulating proliferation and survival of glioma cancer stem cells. Targeting core stem cell pathways may offer improved therapeutic approaches for advanced cancers.
Open Access
Event reconstruction in a liquid xenon Time Projection Chamber with an optically-open field cage
(Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2021-06-01) Stiegler, T; Sangiorgio, S; Brodsky, JP; Heffner, M; Kharusi, SA; Anton, G; Arnquist, IJ; Badhrees, I; Barbeau, PS; Beck, D; Belov, V; Bhatta, T; Bolotnikov, A; Breur, PA; Brown, E; Brunner, T; Caden, E; Cao, GF; Cao, L; Chambers, C; Chana, B; Charlebois, SA; Chiu, M; Cleveland, B; Coon, M; Craycraft, A; Dalmasson, J; Daniels, T; Darroch, L; De, A; Mesrobian-Kabakian, AD; Deslandes, K; DeVoe, R; Di Vacri, ML; Dilling, J; Ding, YY; Dolinski, MJ; Dragone, A; Echevers, J; Edaltafar, F; Elbeltagi, M; Fabris, L; Fairbank, D; Fairbank, W; Farine, J; Ferrara, S; Feyzbakhsh, S; Gallina, G; Gautam, P; Giacomini, G; Goeldi, D; Gornea, R; Gratta, G; Hansen, EV; Hoppe, EW; Hößl, J; House, A; Hughes, M; Iverson, A; Jamil, A; Jewell, MJ; Jiang, XS; Karelin, A; Kaufman, LJ; Koffas, T; Krücken, R; Kuchenkov, A; Kumar, KS; Lan, Y; Larson, A; Leach, KG; Lenardo, BG; Leonard, DS; Li, G; Li, S; Li, Z; Licciardi, C; Lv, P; MacLellan, R; Massacret, N; McElroy, T; Medina-Peregrina, M; Michel, T; Mong, B; Moore, DC; Murray, K; Nakarmi, P; Natzke, CR; Newby, RJ; Ni, K; Ning, Z; Njoya, O; Nolet, F; Nusair, O; Odgers, K; Odian, A; Oriunno, M; Orrell, JL; Ortega, GS; Ostrovskiy, I
nEXO is a proposed tonne-scale neutrinoless double beta decay (0νββ) experiment using liquid 136Xe (LXe) in a Time Projection Chamber (TPC) to read out ionization and scintillation signals. Between the field cage and the LXe vessel, a layer of LXe (“skin” LXe) is present, where no ionization signal is collected. Only scintillation photons are detected, owing to the lack of optical barrier around the field cage. In this work, we show that the light originating in the skin LXe region can be used to improve background discrimination by 5% over previous published estimates. This improvement comes from two elements. First, a fraction of the γ-ray background is removed by identifying light from interactions with an energy deposition in the skin LXe. Second, background from 222Rn dissolved in the skin LXe can be efficiently rejected by tagging the α decay in the 214Bi-214Po chain in the skin LXe.
Open Access
Fern genomes elucidate land plant evolution and cyanobacterial symbioses.
(Nature plants, 2018-07-02) Li, F; Brouwer, P; Carretero-Paulet, L; Cheng, S; De Vries, J; Delaux, P; Eily, A; Koppers, N; Kuo, L; Li, Z
Ferns are the closest sister group to all seed plants, yet little is known about their genomes other than that they are generally colossal. Here, we report on the genomes of Azolla filiculoides and Salvinia cucullata (Salviniales) and present evidence for episodic whole-genome duplication in ferns-one at the base of 'core leptosporangiates' and one specific to Azolla. One fern-specific gene that we identified, recently shown to confer high insect resistance, seems to have been derived from bacteria through horizontal gene transfer. Azolla coexists in a unique symbiosis with N2-fixing cyanobacteria, and we demonstrate a clear pattern of cospeciation between the two partners. Furthermore, the Azolla genome lacks genes that are common to arbuscular mycorrhizal and root nodule symbioses, and we identify several putative transporter genes specific to Azolla-cyanobacterial symbiosis. These genomic resources will help in exploring the biotechnological potential of Azolla and address fundamental questions in the evolution of plant life.
Open Access
Modular Multilevel Series/Parallel Converter for Bipolar DC Distribution and Transmission
(IEEE Journal of Emerging and Selected Topics in Power Electronics, 2020) Lizana F., R; Rivera, S; Li, Z; Dekka, A; Rosenthal, L; Bahamonde I., H; Peterchev, AV; Goetz, SM
Open Access
Modulation and Control of Series/Parallel Module for Ripple-Current Reduction in Star-Configured Split-Battery Applications
(IEEE Transactions on Power Electronics, 2020) Li, Z; Lizana, R; Yu, Z; Sha, S; Peterchev, AV; Goetz, SM
Open Access
Multilevel Converters with Symmetrical Half-Bridge Submodules and Sensorless Voltage Balance
(IEEE Transactions on Power Electronics, 2020) Fang, J; Li, Z; Goetz, SM
Open Access
Noninvasive Detection of Motor-Evoked Potentials in Response to Brain Stimulation Below the Noise Floor-How Weak Can a Stimulus Be and Still Stimulate.
(Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference, 2018-07) Goetz, SM; Li, Z; Peterchev, AV
Motor-evoked potentials (MEP) are one of the most important responses to brain stimulation, such as supra-threshold transcranial magnetic stimulation (TMS) and electrical stimulation. The understanding of the neurophysiology and the determination of the lowest stimulation strength that evokes responses requires the detection of even smallest responses, e.g., from single motor units, but available detection and quantization methods are rather simple and suffer from a large noise floor. The paper introduces a more sophisticated matched-filter detection method that increases the detection sensitivity and shows that activation occurs well below the conventional detection level. In consequence, also conventional threshold definitions, e.g., as 50 μV median response amplitude, turn out to be substantially higher than the point at which first detectable responses occur. The presented method uses a matched-filter approach for improved sensitivity and generates the filter through iterative learning from the presented data. In contrast to conventional peak-to-peak measures, the presented method has a higher signal-to-noise ratio (≥14 dB). For responses that are reliably detected by conventional detection, the new approach is fully compatible and provides the same results but extends the dynamic range below the conventional noise floor. The underlying method is applicable to a wide range of well-timed biosignals and evoked potentials, such as in electroencephalography.
Open Access
Search for Majoron-emitting modes of $^{136}$Xe double beta decay with the complete EXO-200 dataset
Kharusi, S Al; Anton, G; Badhrees, I; Barbeau, PS; Beck, D; Belov, V; Bhatta, T; Breidenbach, M; Brunner, T; Cao, GF; Cen, WR; Chambers, C; Cleveland, B; Coon, M; Craycraft, A; Daniels, T; Darroch, L; Daugherty, SJ; Davis, J; Delaquis, S; Mesrobian-Kabakian, A Der; DeVoe, R; Dilling, J; Dolgolenko, A; Dolinski, MJ; Echevers, J; Jr, W Fairbank; Fairbank, D; Farine, J; Feyzbakhsh, S; Fierlinger, P; Fudenberg, D; Gautam, P; Gornea, R; Gratta, G; Hall, C; Hansen, EV; Hoessl, J; Hufschmidt, P; Hughes, M; Iverson, A; Jamil, A; Jessiman, C; Jewell, MJ; Johnson, A; Karelin, A; Kaufman, LJ; Koffas, T; ucken, R Kr; Kuchenkov, A; Kumar, KS; Lan, Y; Larson, A; Lenardo, BG; Leonard, DS; Li, GS; Li, S; Li, Z; Licciardi, C; Lin, YH; MacLellan, R; McElroy, T; Michel, T; Mong, B; Moore, DC; Murray, K; Njoya, O; Nusair, O; Odian, A; Ostrovskiy, I; Perna, A; Piepke, A; Pocar, A; Retiere, F; Robinson, AL; Rowson, PC; Rudde, D; Runge, J; Schmidt, S; Sinclair, D; Skarpaas, K; Soma, AK; Stekhanov, V; Tarka, M; Thibado, S; Todd, J; Tolba, T; Totev, TI; Tsang, R; Veenstra, B; Veeraraghavan, V; Vogel, P; Vuilleumier, J-L; Wagenpfeil, M; Watkins, J; Weber, M; Wen, LJ; Wichoski, U; Wrede, G; Wu, SX; Xia, Q; Yahne, DR; Yang, L; Yen, Y-R; Zeldovich, O Ya; Ziegler, T
A search for Majoron-emitting modes of the neutrinoless double-beta decay of $^{136}$Xe is performed with the full EXO-200 dataset. This dataset consists of a total $^{136}$Xe exposure of 234.1 kg$\cdot$yr, and includes data with detector upgrades that have improved the energy threshold relative to previous searches. A lower limit of T$_{1/2}^{\rm{^{136}Xe}}>$4.3$\cdot$10$^{24}$ yr at 90\% C.L. on the half-life of the spectral index $n=1$ Majoron decay was obtained, a factor of 3.6 more stringent than the previous limit from EXO-200, corresponding to a constraint on the Majoron-neutrino coupling constant of $|\langle g_{ee}^{M}\rangle|$$<(0.4$-$0.9)\cdot10^{-5}$. The lower threshold and the additional data taken resulted in a factor 8.4 improvement for the $n=7$ mode compared to the previous EXO search. This search provides the most stringent limits to-date on the Majoron-emitting decays of $^{136}$Xe with spectral indices $n=1,2,3,$ and 7.
Open Access
The EXO-200 detector, part II: Auxiliary Systems
Ackerman, N; Albert, J; Auger, M; Auty, DJ; Badhrees, I; Barbeau, PS; Bartoszek, L; Baussan, E; Belov, V; Benitez-Medina, C; Bhatta, T; Breidenbach, M; Brunner, T; Cao, GF; Cen, WR; Chambers, C; Cleveland, B; Conley, R; Cook, S; Coon, M; Craddock, W; Craycraft, A; Cree, W; Daniels, T; Darroch, L; Daugherty, SJ; Daughhetee, J; Davis, CG; Davis, J; Delaquis, S; Mesrobian-Kabakian, A Der; deVoe, R; Didberidze, T; Dilling, J; Dobi, A; Dolgolenko, AG; Dolinski, MJ; Dunford, M; Echevers, J; Espic, L; Jr, W Fairbank; Fairbank, D; Farine, J; Feldmeier, W; Feyzbakhsh, S; Fierlinger, P; Fouts, K; Franco, D; Freytag, D; Fudenberg, D; Gautam, P; Giroux, G; Gornea, R; Graham, K; Gratta, G; Hagemann, C; Hall, C; Hall, K; Haller, G; Hansen, EV; Hargrove, C; Herbst, R; Herrin, S; Hodgson, J; Hughes, M; Iverson, A; Jamil, A; Jessiman, C; Jewell, MJ; Johnson, A; Johnson, TN; Johnston, S; Karelin, A; Kaufman, LJ; Killick, R; Koffas, T; Kravitz, S; Krücken, R; Kuchenkov, A; Kumar, KS; Lan, Y; Larson, A; Leonard, DS; Leonard, F; LePort, F; Li, GS; Li, S; Li, Z; Licciardi, C; Lin, YH; Mackay, D; MacLellan, R; Marino, M; Martin, J-M; Martin, Y; McElroy, T; McFarlane, K; Michel, T; Mong, B; Moore, DC; Murray, K; Neilson, R; Njoya, O; Nusair, O; O'Sullivan, K; Odian, A; Ostrovskiy, I; Ouellet, C; Piepke, A; Pocar, A; Prescott, CY; Pushkin, K; Retiere, F; Rivas, A; Robinson, AL; Rollin, E; Rowson, PC; Rozo, MP; Runge, J; Russell, JJ; Schmidt, S; Schubert, A; Sinclair, D; Skarpaas, K; Slutsky, S; Smith, E; Soma, AK; Stekhanov, V; Strickland, V; Swift, M; Tarka, M; Todd, J; Tolba, T; Tosi, D; Totev, TI; Tsang, R; Twelker, K; Veenstra, B; Veeraraghavan, V; Vuilleumier, J-L; Vuilleumier, J-M; Wagenpfeil, M; Waite, A; Walton, J; Walton, T; Wamba, K; Watkins, J; Weber, M; Wen, LJ; Wichoski, U; Wittgen, M; Wodin, J; Wood, J; Wrede, G; Wu, SX; Xia, Q; Yang, L; Yen, Y-R; Zeldovich, O Ya; Ziegler, T
The EXO-200 experiment searched for neutrinoless double-beta decay of $^{136}$Xe with a single-phase liquid xenon detector. It used an active mass of 110 kg of 80.6%-enriched liquid xenon in an ultra-low background time projection chamber with ionization and scintillation detection and readout. This paper describes the design and performance of the various support systems necessary for detector operation, including cryogenics, xenon handling, and controls. Novel features of the system were driven by the need to protect the thin-walled detector chamber containing the liquid xenon, to achieve high chemical purity of the Xe, and to maintain thermal uniformity across the detector.
Open Access
Up-regulation of tissue factor in human pulmonary artery endothelial cells after ultrafine particle exposure.
(Environmental health perspectives, 2007-04) Karoly, ED; Li, Z; Dailey, LA; Hyseni, X; Huang, YC
BACKGROUND: Epidemiology studies have linked exposure to pollutant particles to increased cardiovascular mortality and morbidity, but the mechanisms remain unknown. OBJECTIVES: We tested the hypothesis that the ultrafine fraction of ambient pollutant particles would cause endothelial cell dysfunction. METHODS: We profiled gene expression of human pulmonary artery endothelial cells (HPAEC) exposed to ultrafine particles (UFPs; 100 microg/mL) from Chapel Hill, North Carolina, or vehicle for 4 hr with Affymetrix HG U133 Plus 2.0 chips (n = 4 each). RESULTS: We found 320 up-regulated genes and 106 down-regulated genes (p < 0.01, 5% false discovery rate). We noted up-regulation of genes related to coagulation [tissue factor (F3) and coagulation factor II receptor-like 2 (F2RL2)] and differential regulation of genes related to F3 signaling (FOS, JUN, and NFKBIA). Results of quantitative polymerase chain reaction show a significant up-regulation of F3 after 10 and 100 microg/mLUFP exposures. Additionally, the water-soluble fractions of UFPs were sufficient to induce the expression of F3, F2RL2, and heme oxygenase 1 (HMOX1). Treatment of HPAEC with UFPs for 16 hr increased the release of interleukin (IL)-6 and IL-8. Pretreatment of HPAEC with a blocking antibody against F3 attenuated IL-6 and IL-8 release by 30 and 70%, respectively. CONCLUSIONS: Using gene profiling, we discovered that UFPs may induce vascular endothelial cells to express genes related to clotting. These results indicate that PM may cause adverse cardiovascular health effects by activating coagulation-inflammation circuitry.