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Ren, Y. (author), Hovenier, J.N. (author), Cui, M. (author), Hayton, D.J. (author), Gao, J.R. (author), Klapwijk, T.M. (author), Shi, S.C. (author), Kao, T.Y. (author), Hu, Q. (author), Reno, J.L. (author)We report frequency locking of two 3.5-THz third-order distributed feedback (DFB) quantum cascade lasers (QCLs) by using methanol molecular absorption lines, a proportional-integral-derivative controller, and a NbN bolometer. We show that the free-running linewidths of the QCLs are dependent on the electrical and temperature tuning coefficients....journal article 2012
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- Koleva, D.A. (author), Hu, J. (author), Van Breugel, K. (author), Boshkov, N. (author), Radeva, T. (author), Milkova, V. (author) journal article 2010
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Ren, Y. (author), Hovenier, J.N. (author), Higgins, R. (author), Gao, J.R. (author), Klapwijk, T.M. (author), Shi, S.C. (author), Bell, A. (author), Klein, B. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author)A terahertz (THz) heterodyne spectrometer is demonstrated based on a quantum cascade laser (QCL) as a local oscillator (LO) and an NbN hot electron bolometer as a mixer, and it is used to measure high-resolution molecular spectral lines of methanol (CH3OH) between 2.913–2.918 THz. The spectral lines are taken from a gas cell containing methanol...journal article 2010
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Ren, Y. (author), Hovenier, J.N. (author), Higgins, R. (author), Gao, J.R. (author), Klapwijk, T.M. (author), Shi, S.C. (author), Klein, B. (author), Kao, T.Y. (author), Hu, Q. (author), Reno, J.L. (author)A frequency tunable terahertz heterodyne spectrometer, based on a third-order distributed feedback quantum cascade laser as a local oscillator, has been demonstrated by measuring molecular spectral lines of methanol (CH3OH) gas at 3.5 THz. By varying the bias voltage of the laser, we achieved a tuning range of ? 1?GHz of the lasing frequency,...journal article 2011
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Koleva, D.A. (author), Hu, J. (author), Van Breugel, K. (author), De Wit, J.H.W. (author), Boshkov, N. (author)An improved cathodic protection (CP), based on pulse regime was investigated in reinforced concrete, compared to conventional CP. Both regimes used CP current in the range of 2 to15 mA/m2. A voltage-to-current converter maintained the pulse current, the latter adjusted with duty cycle of 12% to 50 % and frequency of 500 Hz to 1 kHz. The...journal article 2006
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Adam, A.J.L. (author), Kaalynas, I. (author), Hovenier, J.N. (author), Klaassen, T.O. (author), Gao, J.R. (author), Orlova, E.E. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author)The need to reach single-mode lasing and minimize at the same time the electrical dissipation of cryogenically operated terahertz quantum cascade lasers may result in small and subwavelength cavity dimensions. To assess the influence of such dimensions on the shape of the laser emission, we have measured the beam pattern of two metal-metal...journal article 2006
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- Koleva, D.A. (author), Hu, J. (author), Van Breugel, K. (author), Boshkov, N. (author) journal article 2010
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Whiting, N. (author), Hu, J. (author), Shah, J.V. (author), Cassidy, M.C. (author), Cressman, E. (author), Millward, N.Z. (author), Menter, D.G. (author), Marcus, C.M. (author), Bhattacharya, P.K. (author)Visualizing the movement of angiocatheters during endovascular interventions is typically accomplished using x-ray fluoroscopy. There are many potential advantages to developing magnetic resonance imaging-based approaches that will allow three-dimensional imaging of the tissue/vasculature interface while monitoring other physiologically-relevant...journal article 2015
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- Koleva, D.A. (author), Hu, J. (author), Van Breugel, K. (author), Boshkov, N. (author), De Wit, H. (author) journal article 2005
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Hu, Z. (author), Van Alen, T. (author), Jetten, M.S.M. (author), Kartal, B. (author)Anaerobic ammonium-oxidizing (anammox) planctomycetes oxidize ammonium in the absence of molecular oxygen with nitrite as the electron acceptor. Although planctomycetes are generally assumed to lack peptidoglycan in their cell walls, recent genome data imply that the anammox bacteria have the genes necessary to synthesize peptidoglycan-like cell...journal article 2013
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Hu, J. (author), Koleva, D.A. (author), Van Breugel, K. (author)This paper reports the main results from the influence of the initially admixed nano-aggregates (0.5 g/l PEO113-b-PS70 micelles previously dissolved in demi-water) on microstructural alterations of the reinforced mortar subjected to chloride induced corrosion. The morphology of hydration/corrosion products at the steel/cement paste interface and...journal article 2011
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Nikerel, I.E. (author), Berkhout, J. (author), Hu, F. (author), Teusink, B. (author), Reinders, M.J.T. (author), De Ridder, D. (author)Understanding cellular regulation of metabolism is a major challenge in systems biology. Thus far, the main assumption was that enzyme levels are key regulators in metabolic networks. However, regulation analysis recently showed that metabolism is rarely controlled via enzyme levels only, but through non-obvious combinations of hierarchical ...journal article 2012
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Koleva, D.A. (author), Hu, J. (author), De Wit, J.H.W. (author), Boshkov, N. (author), Radeva, T. (author), Milkova, V. (author), Van Breugel, K. (author)This work reports on the electrochemical performance of low-carbon steel electrodes in model alkaline solutions in the presence of 4.9.10-4 g/l hybrid aggregates i.e. cement extract, containing PDADMAC (poly (diallyl, dimethyl ammonium chloride) / PAA (Poly (acrylic acid)/ PDADMAC over a CaO core. The main objective was to determine if the...journal article 2010
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Gao, J.R. (author), Hovenier, J.N. (author), Yang, Z.Q. (author), Baselmans, J.J.A. (author), Baryshev, A. (author), Hajenius, M. (author), Klapwijk, T.M. (author), Adam, A.J.L. (author), Klaassen, T.O. (author), Williams, B.S. (author), Kumar, S. (author), Hu, Q. (author), Reno, J.L. (author)We report the first demonstration of an all solid-state heterodyne receiver that can be used for high-resolution spectroscopy above 2?THz suitable for space-based observatories. The receiver uses a NbN superconducting hot-electron bolometer as mixer and a quantum cascade laser operating at 2.8?THz as local oscillator. We measure a double...journal article 2005
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Hayton, D.J. (author), Khudchenko, A. (author), Pavelyev, D.G. (author), Hovenier, J.N. (author), Baryshev, A. (author), Gao, J.R. (author), Kao, T.Y. (author), Hu, Q. (author), Reno, J.L. (author), Vaks, V. (author)We report on the phase locking of a 3.4 THz third-order distributed feedback quantum cascade laser (QCL) using a room temperature GaAs/AlAs superlattice diode as both a frequency multiplier and an internal harmonic mixer. A signal-to-noise level of 60?dB is observed in the intermediate frequency signal between the 18th harmonic of a 190.7?GHz...journal article 2013
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Hu, J. (author), Koleva, D.A. (author), Van Breugel, K. (author)This study presents the results from a preliminary investigation on the corrosion behavior of carbon steel in cement extract (CE) in the presence of very low concentration (0.0024 wt. %) polymeric nano-aggregates (PEO113-b-PS780 vesicles). Two types of vesicles were studied: vesicles with a CaO-containing core and vesicles with an “empty” core....journal article 2012
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Hu, Z. (author), Lotti, T. (author), De Kreuk, B.M. (author), Kleerebezem, R. (author), Van Loosdrecht, M. (author), Kruit, J. (author), Jetten, M.S.M. (author), Kartala, B. (author)Currently, nitritation-anammox (anaerobic ammonium oxidation) bioreactors are designed to treat wastewaters with high ammonium concentrations at mesophilic temperatures (25 to 40°C). The implementation of this technology at ambient temperatures for nitrogen removal from municipal wastewater following carbon removal may lead to more-sustainable...journal article 2013
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- Hu, J. (author), Koleva, D.A. (author), Ma, Y. (author), Schlangen, E. (author), Van Breugel, K. (author) journal article 2013
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Hu, Z. (author), Wang, Z.B. (author), Zitman, T.J. (author), Stive, M.J.F. (author), Bouma, T.J. (author)Dynamic equilibrium theory is a fruitful concept, which we use to systematically explain the tidal flat morphodynamic response to tidal currents, wind waves, sediment supply, and other sedimentological drivers. This theory stems from a simple analytical model that derives the tide- or wave-dominated tidal flat morphology by assuming that...journal article 2015
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Ren, Y. (author), Hayton, D.J. (author), Hovenier, J.N. (author), Cui, M. (author), Gao, J.R. (author), Klapwijk, T.M. (author), Shi, S.C. (author), Kao, T.Y. (author), Hu, Q. (author), Reno, J.L. (author)We demonstrate an experimental scheme to simultaneously stabilize the frequency and amplitude of a 3.5 THz third-order distributed feedback quantum cascade laser as a local oscillator. The frequency stabilization has been realized using a methanol absorption line, a power detector, and a proportional-integral-derivative (PID) loop. The amplitude...journal article 2012