179 results on '"van der Laan T"'
Search Results
2. Model-based approach for the automatic inclusion of production considerations in the conceptual design of aircraft structures
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Bruggeman, A.M.R.M. (author), Bansal, D. (author), la Rocca, G. (author), van der Laan, T (author), van den Berg, T. (author), Bruggeman, A.M.R.M. (author), Bansal, D. (author), la Rocca, G. (author), van der Laan, T (author), and van den Berg, T. (author)
- Abstract
Including production considerations in the early design stages of aircraft structures is challenging. Production information is mostly known by experts and rarely formally documented such that it can be effectively used during the design process. Producibility is mostly considered after completing the design, resulting in increased cost and development time due to the late discovery of production issues. This paper presents a new model, called the Manufacturing Information Model (MIM), which supports the automatic inclusion of production considerations into the design process. The MIM provides a single source of truth and a generic structure to capture and organize production-related information in a product system. Furthermore, it provides compatibility analyses to automatically warn for or exclude infeasible designs. Analysis tools use the information stored within the MIM to calculate the mass, costs, and production rate of the product. To show the functionalities of the MIM, it has been applied to the conceptual design of a wing box at a Tier 1 company. This use case shows how the MIM supports trade-off decisions, as it allows for the identification of trends and the ranking of different manufacturing concepts. Overall, the MIM provides a structured and formal approach to include production information in the conceptual design, improving the decision-making process., Flight Performance and Propulsion
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- 2024
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3. Heating and cooling of the neutral ISM in the NGC4736 circumnuclear ring
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van der Laan, T. P. R., Armus, L., Beirao, P., Sandstrom, K., Groves, B., Schinnerer, E., Draine, B. T., Smith, J. D., Galametz, M., Wolfire, M., Croxall, K., Dale, D., Camus, R. Herrera, Calzetti, D., and Kennicutt Jr, R. C.
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Astrophysics - Astrophysics of Galaxies - Abstract
The manner in which gas accretes and orbits within circumnuclear rings has direct implications for the star formation process. In particular, gas may be compressed and shocked at the inflow points, resulting in bursts of star formation at these locations. Afterwards the gas and young stars move together through the ring. In addition, star formation may occur throughout the ring, if and when the gas reaches sufficient density to collapse under gravity. These two scenarios for star formation in rings are often referred to as the `pearls on a string' and `popcorn' paradigms. In this paper, we use new Herschel PACS observations, obtained as part of the KINGFISH Open Time Key Program, along with archival Spitzer and ground-based observations from the SINGS Legacy project, to investigate the heating and cooling of the interstellar medium in the nearby star-forming ring galaxy, NGC4736. By comparing spatially resolved estimates of the stellar FUV flux available for heating, with the gas and dust cooling derived from the FIR continuum and line emission, we show that while star formation is indeed dominant at the inflow points in NGC 4736, additional star formation is needed to balance the gas heating and cooling throughout the ring. This additional component most likely arises from the general increase in gas density in the ring over its lifetime. Our data provide strong evidence, therefore, for a combination of the two paradigms for star formation in the ring in NGC4736., Comment: accepted for publication in A&A
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- 2015
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4. A Detection of Molecular Gas Emission in the Host Galaxy of GRB 080517
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Stanway, E. R., Levan, A. J., Tanvir, N. R., Wiersema, K., and van der Laan, T. P. R.
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Astrophysics - Astrophysics of Galaxies - Abstract
We have observed the host galaxy of the low redshift, low luminosity GRB 080517 at 105.8 GHz using the IRAM Plateau de Bure interferometer. We detect an emission line with integrated flux S.delta{nu} = 0.39 +/- 0.05 Jy km/s - consistent both spatially and in velocity with identification as the J=1-0 rotational transition of carbon monoxide (CO) at the host galaxy redshift. This represents only the third long GRB host galaxy with molecular gas detected in emission. The inferred molecular gas mass, M_H2 ~ 6.3 x 10^8 M_sun, implies a gas consumption timescale of ~40 Myr if star formation continues at its current rate. Similar short timescales appear characteristic of the long GRB population with CO observations to date, suggesting that the gamma-ray burst in these sources occurs towards the end of their star formation episode., Comment: Accepted for publication in Astrophysical Journal Letters. 5 pages
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- 2014
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5. Near-Infrared long-slit spectra of Seyfert Galaxies: gas excitation across the central kiloparsec
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van der Laan, T. P. R., Schinnerer, E., Boeker, T., and Armus, L.
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Astrophysics - Galaxy Astrophysics ,Astrophysics - Cosmology and Extragalactic Astrophysics - Abstract
The excitation of the gas phase of the interstellar medium can be driven by various mechanisms. In galaxies with an active nucleus, such as Seyfert galaxies, both radiative and mechanical energy from the central black hole, or the stars in the disk surrounding it may play a role. We investigate the relative importance and range of influence of the active galactic nucleus for the excitation of ionized and molecular gas in the central kiloparsec of its host galaxy. We present H- and K-band long-slit spectra for a sample of 21 nearby (D <70 Mpc) Seyfert galaxies obtained with the NIRSPEC instrument on the Keck telescope. For each galaxy, we fit the nebular line emission, stellar continua, and warm molecular gas as a function of distance from the nucleus. Our analysis does not reveal a clear difference between the nucleus proper and off-nuclear environment in terms of excitation mechanisms, suggesting that the influence of an AGN reaches far into the disk of the host galaxy. The radial variations in emission line ratios indicate that, while local mechanisms do affect the gas excitation, they are often averaged out when measuring over extended regions. The fully calibrated long-slit spectra, as well as our fitting results, are made available on-line., Comment: Published in A&A. The fully calibrated long-slit spectra, as well as our fitting results, are available on-line via the CDS
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- 2014
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6. Explaining two circumnuclear star forming rings in NGC5248
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van der Laan, T. P. R., Schinnerer, E., Emsellem, E., Meidt, S., Dumas, G., Boeker, T., Hunt, L., Haan, S., Mundell, C., and Wozniak, H.
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Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
The distribution of gas in the central kiloparsec of a galaxy has a dynamically rapid evolution. Nonaxisymmetries in the gravitational potential of the galactic disk, such as a large scale stellar bar or spiral, can lead to significant radial motion of gaseous material from larger radii to the central region. The large influx of gas and the subsequent star formation keep the central region constantly changing. However, the ability of gas to reach the nucleus proper to fuel an AGN phase is not guaranteed. Gas inflow can be halted at a circumnuclear star forming ring several hundred parsec away. The nearby galaxy NGC5248 is especially interesting in this sense since it is said to host 2 circumnuclear star forming rings at 100pc and 370pc from its quiescent nucleus. Here we present new subarcsecond PdBI+30m CO(2-1) emission line observations of the central region. For the first time the molecular gas distribution at the smallest stellar ring is resolved into a gas ring, consistent with the presence of a quiescent nucleus. However, the molecular gas shows no ring structure at the larger ring. We combine analyses of the gaseous and stellar content in the central kiloparsec of this galaxy to understand the gas distribution and dynamics of this star forming central region. We discuss the probability of two scenarios leading to the current observations, given our full understanding of this system, and discuss whether there are really two circumnuclear star forming rings in this galaxy., Comment: Accepted for publication in A&A, 14pages + long table
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- 2013
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7. How does star formation proceed in the circumnuclear starburst ring of NGC 6951?
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van der Laan, T. P. R., Schinnerer, E., Emsellem, E., Hunt, L. K., McDermid, R. M., and Liu, G.
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Astrophysics - Astrophysics of Galaxies - Abstract
Gas inflowing along stellar bars is often stalled at the location of circumnuclear rings, that form an effective reservoir for massive star formation and thus shape the central regions of galaxies. However, how exactly star formation is proceeding within these circumnuclear starburst rings is subject of debate. Two main scenarios for this process have been put forward: In the first the onset of star formation is regulated by the total amount of gas present in the ring with star forming starting once a mass threshold has reached in a `random' position within the ring like `popcorn'. In the second star formation preferentially takes place near the locations where the gas enters the ring. This scenario has been dubbed `pearls-on-a-string'. Here we combine new optical IFU data covering the full stellar bar with existing multi-wavelength data to study in detail the 580 pc radius circumnuclear starburst ring in the nearby spiral galaxy NGC 6951. Using HST archival data together with Sauron and Oasis IFU data, we derive the ages and stellar masses of star clusters as well as the total stellar content of the central region. Adding information on the molecular gas distribution, stellar and gaseous dynamics and extinction, we find that the circumnuclear ring in NGC 6951 is ~1-1.5 Gyr old and has been forming stars for most of that time. We see evidence for preferred sites of star formation within the ring, consistent with the `pearls-on-a-string' scenario, when focusing on the youngest stellar populations. Due to the ring's longevity this signature is washed out when older stellar populations are included in the analysis., Comment: accepted for publication in A&A, 15 pages
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- 2013
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8. The CO-to-H2 Conversion Factor and Dust-to-Gas Ratio on Kiloparsec Scales in Nearby Galaxies
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Sandstrom, K. M., Leroy, A. K., Walter, F., Bolatto, A. D., Croxall, K. V., Draine, B. T., Wilson, C. D., Wolfire, M., Calzetti, D., Kennicutt, R. C., Aniano, G., Meyer, J. Donovan, Usero, A., Bigiel, F., Brinks, E., de Blok, W. J. G, Crocker, A., Dale, D., Engelbracht, C. W., Galametz, M., Groves, B., Hunt, L. K., Koda, J., Kreckel, K., Linz, H., Meidt, S., Pellegrini, E., Rix, H. -W., Roussel, H., Schinnerer, E., Schruba, A., Schuster, K. -F., Skibba, R., van der Laan, T., Appleton, P., Armus, L., Brandl, B., Gordon, K., Hinz, J., Krause, O., Montiel, E., Sauvage, M., Schmiedeke, A., Smith, J. D. T., and Vigroux, L.
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Astrophysics - Cosmology and Nongalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
We present kiloparsec (kpc) spatial resolution maps of the CO-to-H2 conversion factor (alpha_co) and dust-to-gas ratio (DGR) in 26 nearby, star-forming galaxies. We have simultaneously solved for alpha_co and DGR by assuming that the DGR is approximately constant on kpc scales. With this assumption, we can combine maps of dust mass surface density, CO integrated intensity and HI column density to solve for both alpha_co and DGR with no assumptions about their value or dependence on metallicity or other parameters. Such a study has just become possible with the availability of high resolution far-IR maps from the Herschel key program KINGFISH, 12CO J=(2-1) maps from the IRAM 30m large program HERACLES and HI 21-cm line maps from THINGS. We use a fixed ratio between the (2-1) and (1-0) lines to present our alpha_co results on the more typically used 12CO J=(1-0) scale and show using literature measurements that variations in the line ratio do not effect our results. In total, we derive 782 individual solutions for alpha_co and DGR. On average, alpha_co = 3.1 Msun pc^-2 (K km s^-1)^-1 for our sample with a standard deviation of 0.3 dex. Within galaxies we observe a generally flat profile of alpha_co as a function of galactocentric radius. However, most galaxies exhibit a lower alpha_co in the central kpc---a factor of ~2 below the galaxy mean, on average. In some cases, the central alpha_co value can be factors of 5 to 10 below the standard Milky Way (MW) value of alpha_co,MW =4.4 Msun pc^-2 (K km s^-1)^-1. While for alpha_co we find only weak correlations with metallicity, DGR is well-correlated with metallicity, with an approximately linear slope. Finally, we present several recommendations for choosing an appropriate alpha_co for studies of nearby galaxies., Comment: accepted to ApJ July 9, 2013, 63 pages, 2-column ApJ format, p38-63 are an image atlas
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- 2012
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9. A Study of Heating and Cooling of the ISM in NGC 1097 with Herschel-PACS and Spitzer-IRS
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Beirao, P., Armus, L., Helou, G., Appleton, P. N., Smith, J. -D. T., Croxall, K. V., Murphy, E. J., Dale, D. A., Draine, B. T., Wolfire, M. G., Sandstrom, K. M., Aniano, G., Bolatto, A. D., Groves, B., Brandl, B. R., Schinnerer, E., Crocker, A. F., Hinz, J. L., Rix, H. -W., Kennicutt, R. C., Calzetti, D., de Paz, A. Gil, Dumas, G., Galametz, M., Gordon, K. D., Hao, C. -N., Johnson, B., Koda, J., Krause, O., van der Laan, T., Leroy, A. K., Li, Y., Meidt, S. E., Meyer, J. D., Rahman, N., Roussel, H., Sauvage, M., Srinivasan, S., Vigroux, L., Walter, F., and Warren, B. E.
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Astrophysics - Astrophysics of Galaxies ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
NGC 1097 is a nearby Seyfert 1 galaxy with a bright circumnuclear starburst ring, a strong large-scale bar and an active nucleus. We present a detailed study of the spatial variation of the far infrared (FIR) [CII]158um and [OI]63um lines and mid-infrared H2 emission lines as tracers of gas cooling, and of the polycyclic aromatic hydrocarbon (PAH) bands as tracers of the photoelectric heating, using Herschel-PACS, and Spitzer-IRS infrared spectral maps. We focus on the nucleus and the ring, and two star forming regions (Enuc N and Enuc S). We estimated a photoelectric gas heating efficiency ([CII]158um+[OI]63um)/PAH in the ring about 50% lower than in Enuc N and S. The average 11.3/7.7um PAH ratio is also lower in the ring, which may suggest a larger fraction of ionized PAHs, but no clear correlation with [CII]158{\mu}m/PAH(5.5 - 14um) is found. PAHs in the ring are responsible for a factor of two more [CII]158um and [OI]63um emission per unit mass than PAHs in the Enuc S. SED modeling indicates that at most 25% of the FIR power in the ring and Enuc S can come from high intensity photodissociation regions (PDRs), in which case G0 ~ 10^2.3 and nH ~ 10^3.5 cm^-3 in the ring. For these values of G0 and nH PDR models cannot reproduce the observed H2 emission. Much of the the H2 emission in the starburst ring could come from warm regions in the diffuse ISM that are heated by turbulent dissipation or shocks., Comment: 17 pages, 14 figures, 5 tables; accepted for publication in ApJ
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- 2012
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10. Molecular gas in NUclei of GAlaxies (NUGA) XV. Molecular gas kinematics in the inner 3kpc of NGC6951
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van der Laan, T. P. R., Schinnerer, E., Boone, F., Garcia-Burillo, S., Combes, F., Haan, S., Leon, S., Hunt, L., and Baker, A. J.
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Astrophysics - Astrophysics of Galaxies - Abstract
Within the NUclei of GAlaxies project we have obtained IRAM PdBI and 30m 12CO(1-0) and 12CO(2-1) observations of the spiral galaxy NGC 6951. Previous work shows that there is indirect evidence of gas inflow from 3 kpc down to small radii: a large-scale stellar bar, a prominent starburst ring (r~580 pc) and a LINER/Seyfert 2 nucleus. In this paper we study the gas kinematics as traced by the CO line emission in detail. We quantify the influence of the large-scale stellar bar by constructing an analytical model of the evolution of gas particles in a barred potential. From this model gravitational torques and mass accumulation rates are computed. We compare our model-based gravitational torque results with previous observationally-based ones. The model also shows that the large-scale stellar bar is indeed the dominant force for driving the gas inward, to the starburst ring. Inside the ring itself a nuclear stellar oval might play an important role. Detailed analysis of the CO gas kinematics there shows that emission arises from two co-spatial, but kinematically distinct components at several locations. The main emission component can always be related to the overall bar-driven gas kinematics. The second component exhibits velocities that are larger than expected for gas on stable orbits, has a molecular gas mass of 1.8x10^6Msun, is very likely connected to the nuclear stellar oval, and is consistent with inflowing motion towards the very center. This may form the last link in the chain of gas inflow towards the active galactic nucleus in NGC 6951., Comment: 17 pages, accepted by A&A (17 feb 2011)
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- 2011
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11. Posters presenting the AGILE4.0 Application Cases shown at the AGILE4.0 Open Day
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Van der Laan, T, Bruggeman, A.L.M.R.M., Donelli, G., Fioriti. M., Hansmann, P., Torrigiani, F., Della Vecchia, P., Mandorino, M., and Bussemaker. J.
- Abstract
3 Posters of the Application Cases presented at the AGILE4.0 Open Day
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- 2023
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12. Whole genome sequencing voor screening op resistentie Mycobacterium tuberculosis complex
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de Zwaan, R, Kamst, M, de Neeling, H, van der Laan, T, Mulder, A, Anthony, R, and van Soolingen, D
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- 2023
13. Discovery of novel drug-like antitubercular hits targeting the MEP pathway enzyme DXPS by strategic application of ligand-based virtual screening
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Zhu, D, Johannsen, S, Masini, T, Simonin, C, and van der Laan, T
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- 2022
14. Toward a front loaded design process: MBSE-based technologies to support KBE and MDAO
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La Rocca, G., Bruggeman, A.M.R.M., Kulkarni, A.R., Fernandes, F., van den Berg, T., van der Laan, T., and van Manen, B.
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MBSE ,MDAO - Abstract
Presentation given at the Mechanical, Material and Structures Technology Workshop, September 2022
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- 2022
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15. Bringing Manufacturing into the MDO domain using MBSE
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Van der Laan, T.
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Manufacturing ,MDO - Abstract
Presentation discussing why manufacturing should be considered in the MDO process
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- 2022
16. A Value-driven Quantitative Framework Coupling Aircraft Design, Manufacturing and Supply Chain by Leveraging the AGILE4.0 MBSE-MDO Framework
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Donelli, Giuseppa, Mello, João M.G., Odaguil, Felipe I.K., Lefebvre, Thierry, Bartoli, Nathalie, van der Laan, T., Boggero, Luca, and Nagel, Björn
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value model ,manufacturing ,system architecting ,MBSE ,MDO ,supply chain ,aircraft design - Abstract
The design of future innovative, sustainable and circular aircraft configurations arises the necessity to extend the branches of the aeronautical research to the entire aircraft life-cycle, from the design to the production, to the disposal after the end of the system activity. In this frame, within the EU-funded H2020 AGILE 4.0 project, the concurrent coupling of the three domains of product design, manufacturing and supply chain has been addressed by levering Model-Based Systems Engineering (MBSE) and Multidisciplinary Design and Optimization (MDO) technologies The MBSE models and the MDO preliminary results related to the three- dimensional approach applied to a specific aircraft component, that is the horizontal tail plane, are addressed in this research activity and presented in the paper.
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- 2022
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17. Rapid diagnosis of pyrazinamide-resistant multidrug-resistant tuberculosis using a molecular-based diagnostic algorithm
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Simons, S.O., van der Laan, T., Mulder, A., van Ingen, J., Rigouts, L., Dekhuijzen, P.N.R., Boeree, M.J., and van Soolingen, D.
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- 2014
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18. Nanostructured Graphene Surfaces Promote Different Stages of Bone Cell Differentiation
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Borghi, F. F., Bean, P. A., Evans, M. D. M., van der Laan, T., Kumar, S., and Ostrikov, K.
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- 2018
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19. Electrically tuneable terahertz metasurface enabled by a graphene/gold bilayer structure
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Squires, AD, Gao, X, Du, J, Han, Z, Seo, DH, Cooper, JS, Murdock, AT, Lam, SKH, Zhang, T, van der Laan, T, Squires, AD, Gao, X, Du, J, Han, Z, Seo, DH, Cooper, JS, Murdock, AT, Lam, SKH, Zhang, T, and van der Laan, T
- Abstract
Reconfigurable terahertz electronics devices with high tuneability are pivotal for next-generation high speed wireless communication and sensing technologies. Significant challenges exist for realizing these devices, particularly on the design of smart metastructures that can manipulate electromagnetic radiation at the terahertz frequencies and the fabrication of devices with effective tuneability and reconfigurability. Here, we incorporate graphene into a graphene/gold bilayer superimposed metamaterial structure, which enables efficient electrical tuning of terahertz waves. A 0.2 THz frequency-selective absorber is designed and experimentally developed using this graphene/gold bilayer metamaterial approach. The device demonstrates 16 dB amplitude tuning at 0.2 THz resonance and over 95% broadband modulation at just 6 V bias voltage while maintaining a benchmark high-quality factor resonance performance. The design and fabrication methods presented can be readily applied to produce a myriad of tuneable terahertz devices required for high-speed, reconfigurable THz wireless communication and sensing technologies.
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- 2022
20. Dimensionally controlled graphene-based surfaces for photothermal membrane crystallization.
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Santoro, S, Aquino, M, Han Seo, D, Van Der Laan, T, Lee, M, Sung Yun, J, Jun Park, M, Bendavid, A, Kyong Shon, H, Halil Avci, A, Curcio, E, Santoro, S, Aquino, M, Han Seo, D, Van Der Laan, T, Lee, M, Sung Yun, J, Jun Park, M, Bendavid, A, Kyong Shon, H, Halil Avci, A, and Curcio, E
- Abstract
Membrane-based photothermal crystallization - a pioneering technology for mining valuable minerals from seawater and brines - exploits self-heating nanostructured interfaces to boost water evaporation, so achieving a controlled supersaturation environment that promotes the nucleation and growth of salts. This work explores, for the first time, the use of two-dimensional graphene thin films (2D-G) and three dimensional vertically orientated graphene sheet arrays (3D-G) as potential photothermal membranes applied to the dehydration of sodium chloride, potassium chloride and magnesium sulfate hypersaline solutions, followed by salt crystallization. A systematic study sheds light on the role of vertical alignment of graphene sheets on the interfacial, light absorption and photothermal characteristics of the membrane, impacting on the water evaporation rate and on the crystal size distribution of the investigated salts. Overall, 3D-G facilitates the crystallization of the salts because of superior light-to-heat conversion leading to a 3-fold improvement of the evaporation rate with respect to 2D-G. The exploitation of sunlight graphene-based interfaces is demonstrated as a potential sustainable solution to aqueous wastes valorization via recovery in solid phase of dissolved salts using renewable solar energy.
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- 2022
21. Value-driven Model-Based Optimization coupling Design-Manufacturing-Supply Chain in the Early Stages of Aircraft Development: Strategy and Preliminary Results
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Donelli, Giuseppa, Ciampa, Pier Davide, Lefebvre, Thierry, Bartoli, Nathalie, Mello, João M.G., Odaguil, Felipe I.K., and van der Laan, T.
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manufacturing ,Multidisciplinary Design and Optimization ,MBSE ,Value engineering ,MDO ,supply chain ,aircraft design - Abstract
A value-driven model-based approach concurrently coupling design, manufacturing and supply chain in the early development stage of aircraft design has been developed within the European project AGILE4.0. The benefits of using this methodology have been highlighted by the aeronautical application case focused on the design, manufacturing and supply chain of an horizontal tail plane. Finding a Pareto-front simultaneously optimizing the design, manufacturing and supply chain domains is the next challenge to face. The research activity proposed in this paper represents the first step of this ambitious goal. The objective is to identify the optimization strategy to use for the global optimization campaign by exploring, first, simple and representative Multidisciplinary Design and Optimization (MDO) problems related to the supply chain domain. In the first MDO problem, a 4-objective optimization is executed and then the optimized attributes are aggregated in a single measure named value. In the second MDO problem instead, attributes are first aggregated in a value and then a bi- objective value-cost optimization is executed. Thus, two optimization strategies are investigated, but both lead to the value-cost Pareto-front investigation. The application case addressed in this research activity provides interesting insights for the value-driven optimization strategy to use for future-complex optimization problems involving design, manufacturing and supply chain domains.  
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- 2022
22. Antibiotic Susceptibility of Campylobacter Isolates from Sewage and Poultry Abattoir Drain Water
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Koenraad, P. M. F. J., Jacobs-Reitsma, W. F., Van Der Laan, T., Beumer, R. R., Rombouts, F. M., Newell, Diane G., editor, Ketley, Julian M., editor, and Feldman, Roger A., editor
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- 1996
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23. THz graphene-integrated metasurface for electrically reconfigurable polarization conversion
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Song Li-Zhao, Squires Andrew, van der Laan Timothy, and Du Jia
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electrical modulation ,graphene ,metasurface ,polarization conversion ,terahertz ,Physics ,QC1-999 - Abstract
Terahertz (THz) waves have been widely hailed as a key enabling technology for future sixth generation (6G) wireless networks. Dynamic modulation of their polarization states is of great attraction for high-capacity communications and anisotropic sensing. The development of such technology is, however, still in very early stage owing to the difficulties of realizing electrical reconfigurability for THz devices. Artificially constructed metasurfaces and new nanomaterials, such as graphene, have been shown to provide revolutionary platforms for manipulating and controlling the wave properties, especially at THz frequencies. This work leverages the light–matter interaction in a graphene-integrated metasurface functioning as an electrically reconfigurable THz polarization converter. A novel graphene-gold bilayer topology is applied to construct such a metasurface which enables wide-range electrical tunability of the polarization conversion. Under a y-polarized illumination, the reflected components of x- and y-polarizations are tuned dynamically through an external bias voltage across the metasurface, thereby producing an elliptically polarized wave with tuneable ellipticity and angle. By changing the voltage from 0 V to 12 V, the reflected polarization ellipticity has been tuned from −0.94 to −0.5 at around 240 GHz, featuring linear-to-circular and linear-to-elliptical polarization conversions. Meanwhile, the polarization angle has been modulated from 12° to −23° at around 236 GHz. This work provides an experimentally validated THz graphene-integrated metasurface with wide polarization modulation depths, low biasing voltages and simple configuration. It promises great potential for applications in future THz communications and sensing.
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- 2024
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24. A Model-Based Approach to Trade-Space Evaluation Coupling Design-Manufacturing–Supply Chain in the Early Stages of Aircraft Development
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Donelli, G., Ciampa, P.D., Nagel, B., Lemos, G.F.C., Mello, J.M.G.D., Cuco, A.P.C., and van der Laan, T.
- Subjects
Overall Aircraft Design ,eXtended Design Structure Matrix ,Multidisciplinary Design Analysis Optimization - Abstract
Product design and supply chain management are research domains extensively explored in literature. In the last decades, many studies have highlighted that the integration of these two main domains is a key competence for manufacturing companies to increase profitability and efficiency. However most of these studies optimize the supply chain after freezing the design of the product, still considering the supply chain as the following step in product design. This paper presents a value-driven model-based approach that concurrently links product design to supply chain in the frame of aerospace system design. The modelling of the information flow exchanged between three domains - Manufacturing, Supply Chain, Overall Aircraft Design – represents the first challenge addressed in this paper. Support decision makers in finding the best alternative in a tradespace of proposed solutions, based on measures coming from multiple domains, is the key role of the value model usage. Hence, the challenge of formalizing and modeling the selection criteria in accordance with the decision makers’ expectations. The main output is the “utility-cost” trade-space in which the global design solution combines manufacturing and aircraft performance with the main aspects of the supply chain. Case studies set-up with the support of the industrial partners demonstrate the strengths of this methodology, the possible applications and improvements. According to the industrial partners, this method could represent a key support tool that aerospace companies might use during the early stages of aircraft development when strategic decisions have to be taken.  
- Published
- 2021
25. An open source part cost estimation tool for MDO purposes
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van der Laan, T., Johman, A., van Puffelen, T., Nolet, S., van Maanen, B., Daugulis, E., and van den Berg, T.
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Multi-Disciplinary Optimization - Abstract
Within Multi-Disciplinary Optimization (MDO), multiple disciplines of a part or product are evaluated in order to determine the performance in these disciplines . Manufacturing cost is not a discipline usually evaluated in an MDO analysis. However for aircraft part and component manufacturers manufacturing cost is one of the most important performance indicators because it directly affects the profitability of such companies. Cost is often not included because no cost evaluation tool is available. In this paper a cost estimation tool is presented that relates geometric features to recurring manufacturing cost. The tool uses only data from the public domain and will be open source to ensure anyone can use it, improve it and include manufacturing cost in their MDO frameworks.  
- Published
- 2021
26. A THz spectroscopy study of the electrical properties of graphene thin films post-transfer
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Squires, A. D., primary, Van Der Laan, T., additional, Han, Z. J., additional, and Du, J., additional
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- 2021
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27. Antibiotic Susceptibility of Campylobacter Isolates from Sewage and Poultry Abattoir Drain Water
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Jacobs-Reitsma, W. F., van der Laan, T., Beumer, R. R., and Rombouts, F. M.
- Published
- 1995
28. Rejection of harsh pH saline solutions using graphene membranes
- Author
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Seo, DH, Xie, M, Murdock, AT, van der Laan, T, Lawn, M, Park, MJ, Woo, YC, Pineda, S, Hong, JM, Grigore, M, Yick, S, Han, Z, Millar, G, Gray, S, Ostrikov, K, Shon, HK, Bendavid, A, Seo, DH, Xie, M, Murdock, AT, van der Laan, T, Lawn, M, Park, MJ, Woo, YC, Pineda, S, Hong, JM, Grigore, M, Yick, S, Han, Z, Millar, G, Gray, S, Ostrikov, K, Shon, HK, and Bendavid, A
- Abstract
Water security is a pressing issue for global citizens in the 21st century. Concerns over clean water supply, and the environmental impact of industrial waste water, make water treatment a world-wide problem requiring a simple and effective solution. Membrane distillation is an emerging water purification technique that complements state-of-the-art reverse osmosis processes. Membrane distillation achieves high rejection over a range of salt concentrations while maintaining flux, using a temperature differential as opposed to pressure across the membrane. Importantly the process can be driven using low grade waste heat energy. Current membranes used in membrane distillation do not guarantee stable membrane performance under harsh (high salt and acid or base concentrations) conditions. Here we report, a permeable graphene membrane operating in harsh conditions with no observable degradation. A permeate of pH neutral water with a flux of 25 ± 1 L m−2 h−1 is produced by this membrane through near (99.9 ± 0.1%) ion rejection from 0.6 M sodium chloride at pH 1 and pH 13, over 144 h. More complex ion solutions, including real acid mine drainage waste-water, were also successfully purified. These findings may present a membrane that is suitable to improve water supply and reduce the environmental impact of industrial waste-water.
- Published
- 2021
29. 'Whole genome sequencing' van Mycobacterium tuberculosis complexisolaten
- Author
-
van Soolingen, D, van der Laan, T, de Zwaan, R, Kamst, M, Mulder, A, de Neeling, H, Anthony, R, and Jajou, R
- Published
- 2020
30. Aircraft rudder optimization - A multi-level and knowledge-enabled approach
- Author
-
de Wit, A.J., primary, Lammen, W.F., additional, Vankan, W.J., additional, Timmermans, H., additional, van der Laan, T., additional, and Ciampa, P.D., additional
- Published
- 2020
- Full Text
- View/download PDF
31. Neuroendocrine carcinoma of the larynx - an extraordinary malignancy with high recurrence rates and long survival: Our experience in 11 patients
- Author
-
van der Laan, T. P., van der Laan, B. F.A.M., Plaat, B. E.C., Wedman, J., Van Hemel, B. M., and Halmos, G. B.
- Published
- 2012
- Full Text
- View/download PDF
32. WO 3 nanolayer coated 3D-graphene/sulfur composites for high performance lithium/sulfur batteries
- Author
-
Choi, S, Seo, DH, Kaiser, MR, Zhang, C, Van Der Laan, T, Han, ZJ, Bendavid, A, Guo, X, Yick, S, Murdock, AT, Su, D, Lee, BR, Du, A, Dou, SX, and Wang, G
- Abstract
© 2019 The Royal Society of Chemistry. The lithium-sulfur (Li-S) system is one of the most promising rechargeable battery systems for portable electronics and electrification of vehicles due to a high theoretical capacity and energy density, as well as the low cost and availability of non-toxic sulfur. Polysulfide dissolution however hinders cycling performance and is the main limitation to the stability of the Li-S system. Here, we tackle this challenge by synthesizing 3D-graphene foam from soybean oil through a thermal chemical vapor deposition (CVD) process, which is subsequently loaded with sulfur to form a 3D-graphene-sulfur composite (denoted as S@G composite). The synthesized S@G composite shows high initial discharge capacity (∼1300 mA h g -1 at 0.8 A g -1 ) and capacity retention (∼80% after 200 cycles). Furthermore, a thin layer (∼100 nm) of tungsten oxide (WO 3 ) on the S@G composite dramatically improves the cycling performance of the Li-S system with an initial capacity of 1425 mA h g -1 and approximately 95% capacity retention after 500 cycles. The analysis and theoretical calculation results prove that the novel material and approach can enhance the electrochemical performance of rechargeable Li-S batteries and shed light on developing high-performance energy storage devices for a variety of applications.
- Published
- 2019
33. Determining crystal structures through crowdsourcing and coursework
- Author
-
Horowitz, Scott, Koepnick, Brian, Jain, Neha, Pikkanen, Petri, Shehzad, Raafay, Viosca, Randy, James Fraser, Robert, Leduc, Robert, Madala, Roman, Shnider, Scott, de Boisblanc, Sharon, Butkovich, Slava, Bliven, Spencer, Koldewey, Philipp, Hettler, Stephen, Telehany, Stephen, Schwegmann, Steven A., Parkes, Steven, Kleinfelter, Susan C., Michael Holst, Sven, van der Laan, T. J. A., Bausewein, Thomas, Simon, Vera, Pulley, Warwick, Ahlstrom, Logan S., Hull, William, Kim, Annes Yukyung, Lawton, Alexis, Ruesch, Amanda, Sundar, Anjali, Lawrence, Anna-Lisa, Afrin, Antara, Maheshwer, Bhargavi, Turfe, Bilal, Huebner, Christian, Chapman, Matthew R., Killeen, Courtney Elizabeth, Antebi-Lerrman, Dalia, Luan, Danny, Wolfe, Derek, Pham, Duc, Michewicz, Elaina, Hull, Elizabeth, Pardington, Emily, Galal, Galal Osama, Sun, Grace, Sikkema, Andrew P., Chen, Grace, Anderson, Halie E., Chang, Jane, Hewlett, Jeffrey Thomas, Sterbenz, Jennifer, Lim, Jiho, Morof, Joshua, Lee, Junho, Inn, Juyoung Samuel, Hahm, Kaitlin, Skiba, Meredith A., Roth, Kaitlin, Nair, Karun, Markin, Katherine, Schramm, Katie, Toni Eid, Kevin, Gam, Kristina, Murphy, Lisha, Yuan, Lucy, Kana, Lulia, Daboul, Lynn, Maloney, Finn P., Shammas, Mario Karam, Chason, Max, Sinan, Moaz, Andrew Tooley, Nicholas, Korakavi, Nisha, Comer, Patrick, Magur, Pragya, Savliwala, Quresh, Davison, Reid Michael, Sankaran, Roshun Rajiv, Beinlich, Felix, Lewe, Sam, Tamkus, Saule, Chen, Shirley, Harvey, Sho, Hwang, Sin Ye, Vatsia, Sohrab, Withrow, Stefan, Luther, Tahra K, Manett, Taylor, Johnson, Thomas James, Caglar, Ahmet, Ryan Brash, Timothy, Kuhlman, Wyatt, Park, Yeonjung, Popović, Zoran, Baker, David, Khatib, Firas, Bardwell, James C. A., Coral, Alan, Martin, Raoul, Jensen, Alice Elizabeth, Lubow, Allen, Boitano, Amanda, Lisle, Amy Elizabeth, Maxwell, Andrew T., Failer, Barb, Kaszubowski, Bartosz, Hrytsiv, Bohdan, Vincenzo, Brancaccio, de Melo Cruz, Breno Renan, Tymieniecki, Agnes, McManus, Brian Joseph, Kestemont, Bruno, Vardeman, Carl, Comisky, Casey, Neilson, Catherine, Landers, Catherine R., Ince, Christopher, Buske, Daniel Jon, Totonjian, Daniel, Copeland, David Marshall, Winburn, Amanda A., Murray, David, Jagieła, Dawid, Janz, Dietmar, Wheeler, Douglas C., Cali, Elie, Croze, Emmanuel, Rezae, Farah, Martin, Floyd Orville, Beecher, Gil, de Jong, Guido Alexander, Cooper, Seth, Ykman, Guy, Feldmann, Harald, Chan, Hugo Paul Perez, Kovanecz, Istvan, Vasilchenko, Ivan, Connellan, James C., Borman, Jami Lynne, Norrgard, Jane, Kanfer, Jebbie, Canfield, Jeffrey M., Flatten, Jeff, Slone, Jesse David, Oh, Jimmy, Mitchell, Joanne, Bishop, John, Kroeger, John Douglas, Schinkler, Jonas, McLaughlin, Joseph, Brownlee, June M., Bell, Justin, Fellbaum, Karl Willem, Rogawski, David S., Harper, Kathleen, Abbey, Kirk J., Isaksson, Lennart E., Wei, Linda, Cummins, Lisa N., Miller, Lori Anne, Bain, Lyn, Carpenter, Lynn, Desnouck, Maarten, Sharma, Manasa G., Koropatkin, Nicole M., Belcastro, Marcus, Szew, Martin, Britton, Matthew, Gaebel, Matthias, Power, Max, Cassidy, Michael, Pfützenreuter, Michael, Minett, Michele, Wesselingh, Michiel, Hailu, Tsinatkeab T., Yi, Minjune, Cameron, Neil Haydn Tormey, Bolibruch, Nicholas I., Benevides, Noah, Kathleen Kerr, Norah, Barlow, Nova, Crevits, Nykole Krystyne, Dunn, Paul, Silveira Belo Nascimento Roque, Paulo Sergio, and Riber, Peter
- Subjects
0301 basic medicine ,Structure (mathematical logic) ,Multidisciplinary ,Computer science ,business.industry ,Science ,General Physics and Astronomy ,General Chemistry ,Crowdsourcing ,Article ,General Biochemistry, Genetics and Molecular Biology ,Computer game ,Competition (economics) ,03 medical and health sciences ,030104 developmental biology ,Human–computer interaction ,Coursework ,Feature (machine learning) ,ddc:500 ,business - Abstract
We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit players achieved the most accurate structure. Analysing the target protein of the competition, YPL067C, uncovered a new family of histidine triad proteins apparently involved in the prevention of amyloid toxicity. From this study, we conclude that crystallographers can utilize crowdsourcing to interpret electron density information and to produce structure solutions of the highest quality., Building crystal structures into the electron density is an important step in protein structure solution. Here, the authors recruit online game players, students, and experienced crystallographers to compete in a competition to solve a new structure, and find that crowdsourcing model-building works.
- Published
- 2016
34. In vitro drug susceptibility of Mycobacterium tuberculosis for amikacin, kanamycin and capreomycin
- Author
-
Dijkstra, J A, van der Laan, T, Akkerman, O W, Bolhuis, M S, de Lange, W C M, Kosterink, J G W, van der Werf, T S, Alffenaar, J W C, and van Soolingen, D
- Subjects
carbohydrates (lipids) ,biochemical phenomena, metabolism, and nutrition - Abstract
Amikacin, kanamycin and capreomycin are listed among the most important 2nd line drugs for multidrug resistant tuberculosis. Although amikacin and kanamycin are administered in the same dose and show the same pharmacokinetics, they have different WHO breakpoints suggesting that the two drugs have a different minimal inhibitory concentrations (MIC). The aim of this paper was to investigate possible differences in MIC between the aminoglycosides and capreomycin.Using the direct concentration method, a concentration range of amikacin, kanamycin and capreomycin (0.25, 0.50, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0 and 64.0 mg/L) was tested against 57 clinical Mycobacterium tuberculosis strains. The 7H10 agar plates were examined for mycobacterial growth after 14 days.At 2 mg/L, 48 strains (84%) were inhibited by amikacin and only five strains (9%) were inhibited by kanamycin (p < 0.05, Wilcoxon Signed Rank Test). The median MICs of amikacin, kanamycin and capreomycin were 2, 4 and 8 mg/L, respectively. No difference was observed between multidrug resistant and fully susceptible strains in the MIC-distribution of amikacin, kanamycin and capreomycin.The results indicate that amikacin is more active against M. tuberculosis than kanamycin and capreomycin in the absolute concentration method. The impact of this difference on clinical outcome in daily practice requires a prospective study including pharmacokinetic and pharmacodynamics evaluations.
- Published
- 2018
35. Neonatal teratoma presenting as hygroma colli
- Author
-
Jaarsma, A. S., Tamminga, R. Y. J., de Langen, Z. J., van der Laan, T., Nikkels, P. G. J., and Kimpen, J. L. L.
- Published
- 1994
- Full Text
- View/download PDF
36. Questionnaire on the use of lasers by otorhinolaryngologists in The Netherlands
- Author
-
Annyas, A. A., Van Der Laan, T., and Van Der Meulen, F. W.
- Published
- 1996
37. In Vitro Susceptibility of Mycobacterium tuberculosis to Amikacin, Kanamycin, and Capreomycin
- Author
-
Dijkstra, J. A., primary, van der Laan, T., additional, Akkerman, O. W., additional, Bolhuis, M. S., additional, de Lange, W. C. M., additional, Kosterink, J. G. W., additional, van der Werf, T. S., additional, Alffenaar, J. W. C., additional, and van Soolingen, D., additional
- Published
- 2018
- Full Text
- View/download PDF
38. Multipurpose nanoporous alumina-carbon nanowall bi-dimensional nano-hybrid platform via catalyzed and catalyst-free plasma CVD
- Author
-
Fang, J, Levchenko, I, Van Der Laan, T, Kumar, S, and Ostrikov, K
- Subjects
Nanoscience & Nanotechnology - Abstract
Simple, rapid, plasma-assisted synthesis of large-area arrays of vertically-aligned carbon nanowalls on highly-porous, transparent bare and gold-coated alumina membranes with the two pore sizes is reported. It is demonstrated that the complex patterns of vertically aligned nanowalls can nucleate and form different morphologies in the low-temperature plasmas. The process is stable, and the twofold change in the gas flow (10 and 20 sccm) does not noticeably influence the morphology of the nanowall pattern. Application of a thin (5 nm) gold layer to nanoporous membrane prior to the nanowall growth allows controlling the network morphology. © 2014 Published by Elsevier Ltd. All rights reserved.
- Published
- 2014
39. T2009-rapport Schelde-estuarium
- Author
-
Depreiter, D., Cleveringa, J., van der Laan, T., Maris, T., Ysebaert, T., and Wijnhoven, S.
- Published
- 2014
40. Trimethoprim/sulfamethoxazole susceptibility of Mycobacterium tuberculosis
- Author
-
Alsaad, N., van der Laan, T., van Altena, R., Wilting, K.R., van der Werf, T.S., Stienstra, Y., van Soolingen, D., and Alffenaar, J.W.C.
- Published
- 2013
- Full Text
- View/download PDF
41. Growth and photoluminescence of oriented MoSe2nanosheets produced by hot filament CVD
- Author
-
Wang, B. B., primary, Ostrikov, K., additional, van der Laan, T., additional, Zheng, K., additional, Shao, R., additional, Zhu, M. K., additional, and Zou, S. S., additional
- Published
- 2016
- Full Text
- View/download PDF
42. Nota evaluatie van de Evaluatiemethodiek. T2009 rapportage Schelde-estuarium
- Author
-
Depreiter, D., Cleveringa, J., van der Laan, T., Maris, T., Ysebaert, T., and Wijnhoven, S.
- Published
- 2013
43. Samenvatting T2009 rapportage Schelde-estuarium
- Author
-
Depreiter, D., Cleveringa, J., van der Laan, T., Maris, T., Ysebaert, T., and Wijnhoven, S.
- Published
- 2013
44. The CO-to-H₂ conversion factor and dust-to-gas ratio on kiloparsec scales in nearby galaxies
- Author
-
Sandstrom, KM, Leroy, AK, Walter, F, Bolatto, AD, Croxall, KV, Draine, BT, Wilson, CD, Wolfire, M, Calzetti, D, Kennicutt, RC, Aniano, G, Donovan Meyer, J, Usero, A, Bigiel, F, Brinks, E, de Blok, WJG, Crocker, A, Dale, D, Engelbracht, CW, Galametz, M, Groves, B, Hunt, LK, Koda, J, Kreckel, K, Linz, H, van der Wel, Sharon Meidt, Pellegrini, E, Rix, H-W, Roussel, H, Schinnerer, E, Schruba, A, Schuster, K-F, Skibba, R, van der Laan, T, Appleton, P, Armus, L, Brandl, B, Gordon, K, Hinz, J, Krause, O, Montiel, E, Sauvage, M, Schmiedeke, A, Smith, JDT, and Vigroux, L
- Subjects
DWARF GALAXIES ,ISM [galaxies] ,extinction ,INFRARED-EMISSION ,ISM [infrared] ,VIOLENT ,PHOTODISSOCIATION REGIONS ,STAR-FORMATION ,POLYCYCLIC AROMATIC-HYDROCARBONS ,Physics and Astronomy ,X-FACTOR ,dust ,GIANT MOLECULAR CLOUDS ,SPIRAL GALAXIES ,GAMMA-RAY EMISSION ,molecules [ISM] ,GALACTIC-CENTER - Abstract
We present similar to kiloparsec spatial resolution maps of the CO-to-H-2 conversion factor (alpha(CO)) and dust-to-gas ratio (DGR) in 26 nearby, star-forming galaxies. We have simultaneously solved for alpha(CO) and the DGR by assuming that the DGR is approximately constant on kiloparsec scales. With this assumption, we can combine maps of dust mass surface density, CO-integrated intensity, and H I column density to solve for both alpha(CO) and the DGR with no assumptions about their value or dependence on metallicity or other parameters. Such a study has just become possible with the availability of high-resolution far-IR maps from the Herschel key program KINGFISH, (CO)-C-12 J = (2-1) maps from the IRAM 30 m large program HERACLES, and H I 21 cm line maps from THINGS. We use a fixed ratio between the (2-1) and (1-0) lines to present our alpha(CO) results on the more typically used (CO)-C-12 J = (1-0) scale and show using literature measurements that variations in the line ratio do not affect our results. In total, we derive 782 individual solutions for alpha(CO) and the DGR. On average, alpha(CO) = 3.1M(circle dot) pc(-2) (K km s(-1))(-1) for our sample with a standard deviation of 0.3 dex. Within galaxies, we observe a generally flat profile of alpha(CO) as a function of galactocentric radius. However, most galaxies exhibit a lower alpha(CO) value in the central kiloparsec-a factor of similar to 2 below the galaxy mean, on average. In some cases, the central alpha(CO) value can be factors of 5-10 below the standard Milky Way (MW) value of alpha(CO,MW) = 4.4 M-circle dot pc(-2) (K km s(-1))(-1). While for alpha(CO) we find only weak correlations with metallicity, the DGR is well-correlated with metallicity, with an approximately linear slope. Finally, we present several recommendations for choosing an appropriate alpha(CO) for studies of nearby galaxies.
- Published
- 2013
45. Molecular drug susceptibility testing in the Netherlands: performance of the MTBDRplus and MTBDRsl assays
- Author
-
Simons, S. O., primary, van der Laan, T., additional, de Zwaan, R., additional, Kamst, M., additional, van Ingen, J., additional, Dekhuijzen, P. N. R., additional, Boeree, M. J., additional, and van Soolingen, D., additional
- Published
- 2015
- Full Text
- View/download PDF
46. Heating and cooling of the neutral ISM in the NGC 4736 circumnuclear ring
- Author
-
van der Laan, T. P. R., primary, Armus, L., additional, Beirao, P., additional, Sandstrom, K., additional, Groves, B., additional, Schinnerer, E., additional, Draine, B. T., additional, Smith, J. D., additional, Galametz, M., additional, Wolfire, M., additional, Croxall, K., additional, Dale, D., additional, Herrera Camus, R., additional, Calzetti, D., additional, and Kennicutt, R. C., additional
- Published
- 2015
- Full Text
- View/download PDF
47. A DETECTION OF MOLECULAR GAS EMISSION IN THE HOST GALAXY OF GRB 080517
- Author
-
Stanway, E. R., primary, Levan, A. J., additional, Tanvir, N. R., additional, Wiersema, K., additional, and van der Laan, T. P. R., additional
- Published
- 2014
- Full Text
- View/download PDF
48. In vitro synergy between linezolid and clarithromycin against Mycobacterium tuberculosis
- Author
-
Bolhuis, M. S., primary, van der Laan, T., additional, Kosterink, J. G. W., additional, van der Werf, T. S., additional, van Soolingen, D., additional, and Alffenaar, J.-W. C., additional
- Published
- 2014
- Full Text
- View/download PDF
49. THE CO-TO-H-2 CONVERSION FACTOR AND DUST-TO-GAS RATIO ON KILOPARSEC SCALES IN NEARBY GALAXIES
- Author
-
Sandstrom, K. M., Leroy, A. K., Walter, F., Bolatto, A. D., Croxall, K. V., Draine, B. T., Wilson, C. D., Wolfire, M., Calzetti, D., Kennicutt, R. C., Aniano, G., Meyer, J. Donovan, Usero, A., Bigiel, F., Brinks, E., de Blok, W. J. G., Crocker, A., Dale, D., Engelbracht, C. W., Galametz, M., Groves, B., Hunt, L. K., Koda, J., Kreckel, K., Linz, H., Meidt, S., Pellegrini, E., Rix, H. -W., Roussel, H., Schinnerer, E., Schruba, A., Schuster, K. -F., Skibba, R., van der Laan, T., Appleton, P., Armus, L., Brandl, B., Gordon, K., Hinz, J., Krause, O., Montiel, E., Sauvage, M., Schmiedeke, A., Smith, J. D. T., Vigroux, L., Sandstrom, K. M., Leroy, A. K., Walter, F., Bolatto, A. D., Croxall, K. V., Draine, B. T., Wilson, C. D., Wolfire, M., Calzetti, D., Kennicutt, R. C., Aniano, G., Meyer, J. Donovan, Usero, A., Bigiel, F., Brinks, E., de Blok, W. J. G., Crocker, A., Dale, D., Engelbracht, C. W., Galametz, M., Groves, B., Hunt, L. K., Koda, J., Kreckel, K., Linz, H., Meidt, S., Pellegrini, E., Rix, H. -W., Roussel, H., Schinnerer, E., Schruba, A., Schuster, K. -F., Skibba, R., van der Laan, T., Appleton, P., Armus, L., Brandl, B., Gordon, K., Hinz, J., Krause, O., Montiel, E., Sauvage, M., Schmiedeke, A., Smith, J. D. T., and Vigroux, L.
- Abstract
We present similar to kiloparsec spatial resolution maps of the CO-to-H-2 conversion factor (alpha(CO)) and dust-to-gas ratio (DGR) in 26 nearby, star-forming galaxies. We have simultaneously solved for alpha(CO) and the DGR by assuming that the DGR is approximately constant on kiloparsec scales. With this assumption, we can combine maps of dust mass surface density, CO-integrated intensity, and H I column density to solve for both alpha(CO) and the DGR with no assumptions about their value or dependence on metallicity or other parameters. Such a study has just become possible with the availability of high-resolution far-IR maps from the Herschel key program KINGFISH, (CO)-C-12 J = (2-1) maps from the IRAM 30 m large program HERACLES, and H I 21 cm line maps from THINGS. We use a fixed ratio between the (2-1) and (1-0) lines to present our alpha(CO) results on the more typically used (CO)-C-12 J = (1-0) scale and show using literature measurements that variations in the line ratio do not affect our results. In total, we derive 782 individual solutions for alpha(CO) and the DGR. On average, alpha(CO) = 3.1M(circle dot) pc(-2) (K km s(-1))(-1) for our sample with a standard deviation of 0.3 dex. Within galaxies, we observe a generally flat profile of alpha(CO) as a function of galactocentric radius. However, most galaxies exhibit a lower alpha(CO) value in the central kiloparsec-a factor of similar to 2 below the galaxy mean, on average. In some cases, the central alpha(CO) value can be factors of 5-10 below the standard Milky Way (MW) value of alpha(CO,MW) = 4.4 M-circle dot pc(-2) (K km s(-1))(-1). While for alpha(CO) we find only weak correlations with metallicity, the DGR is well-correlated with metallicity, with an approximately linear slope. Finally, we present several recommendations for choosing an appropriate alpha(CO) for studies of nearby galaxies.
- Published
- 2013
50. Carbon nanorods and graphene-like nanosheets by hot filament CVD: growth mechanisms and electron field emission
- Author
-
Wang, B, Ostrikov, Ken, van der Laan, T, Zheng, K, Wang, J, Yan, Y., Quan, X, Wang, B, Ostrikov, Ken, van der Laan, T, Zheng, K, Wang, J, Yan, Y., and Quan, X
- Abstract
Carbon nanorods and graphene-like nanosheets are catalytically synthesized in a hot filament chemical vapor deposition system with and without plasma enhancement, with gold used as a catalyst. The morphological and structural properties of the carbon nanorods and nanosheets are investigated by field-emission scanning electron microscopy, transmission electron microscopy and micro-Raman spectroscopy. It is found that carbon nanorods are formed when a CH4 + H2 + N2 plasma is present while carbon nanosheets are formed in a methane environment without a plasma. The formation of carbon nanorods and carbon nanosheets are analyzed. The results suggest that the formation of carbon nanorods is primarily a precipitation process while the formation of carbon nanosheets is a complex process involving surface-catalysis, surface diffusion and precipitation influenced by the Gibbs–Thomson effect. The electron field emission properties of the carbon nanorods and graphene-like nanosheets are measured under high-vacuum; it is found that the carbon nanosheets have a lower field emission turn-on than the carbon nanorods. These results are important to improve the understanding of formation mechanisms of carbon nanomaterials and contribute to eventual applications of these structures in nanodevices.
- Published
- 2013
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