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2,370 results on '"Als-Nielsen, J"'

51. Observation of Structural Anisotropy and the Onset of Liquidlike Motion During the Nonthermal Melting of InSb

Author

Gaffney, K. J., primary, Lindenberg, A. M., additional, Larsson, J., additional, Sokolowski-Tinten, K., additional, Blome, C., additional, Synnergren, O., additional, Sheppard, J., additional, Caleman, C., additional, MacPhee, A. G., additional, Weinstein, D., additional, Lowney, D. P., additional, Allison, T., additional, Matthews, T., additional, Falcone, R. W., additional, Cavalieri, A. L., additional, Fritz, D. M., additional, Lee, S. H., additional, Bucksbaum, P. H., additional, Reis, D. A., additional, Rudati, J., additional, Macrander, A. T., additional, Fuoss, P. H., additional, Kao, C. C., additional, Siddons, D. P., additional, Pahl, R., additional, Moffat, K., additional, Als-Nielsen, J., additional, Duesterer, S., additional, Ischebeck, R., additional, Schlarb, H., additional, Schulte-Schrepping, H., additional, Schneider, J., additional, von der Linde, D., additional, Hignette, O., additional, Sette, F., additional, Chapman, H. N., additional, Lee, R. W., additional, Hansen, T. N., additional, Wark, J. S., additional, Bergh, M., additional, Huldt, G., additional, van der Spoel, D., additional, Timneanu, N., additional, Hajdu, J., additional, Akre, R. A., additional, Bong, E., additional, Krejcik, P., additional, Arthur, J., additional, Brennan, S., additional, Luening, K., additional, and Hastings, J. B., additional

Published
2005
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52. Clocking Femtosecond X Rays

Author

Cavalieri, A. L., primary, Fritz, D. M., additional, Lee, S. H., additional, Bucksbaum, P. H., additional, Reis, D. A., additional, Rudati, J., additional, Mills, D. M., additional, Fuoss, P. H., additional, Stephenson, G. B., additional, Kao, C. C., additional, Siddons, D. P., additional, Lowney, D. P., additional, MacPhee, A. G., additional, Weinstein, D., additional, Falcone, R. W., additional, Pahl, R., additional, Als-Nielsen, J., additional, Blome, C., additional, Düsterer, S., additional, Ischebeck, R., additional, Schlarb, H., additional, Schulte-Schrepping, H., additional, Tschentscher, Th., additional, Schneider, J., additional, Hignette, O., additional, Sette, F., additional, Sokolowski-Tinten, K., additional, Chapman, H. N., additional, Lee, R. W., additional, Hansen, T. N., additional, Synnergren, O., additional, Larsson, J., additional, Techert, S., additional, Sheppard, J., additional, Wark, J. S., additional, Bergh, M., additional, Caleman, C., additional, Huldt, G., additional, van der Spoel, D., additional, Timneanu, N., additional, Hajdu, J., additional, Akre, R. A., additional, Bong, E., additional, Emma, P., additional, Krejcik, P., additional, Arthur, J., additional, Brennan, S., additional, Gaffney, K. J., additional, Lindenberg, A. M., additional, Luening, K., additional, and Hastings, J. B., additional

Published
2005
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53. Unraveling heme detoxification in the malaria parasite by in situ correlative X-ray fluorescence microscopy and soft X-ray tomography.

Author

Kapishnikov S, Grolimund D, Schneider G, Pereiro E, McNally JG, Als-Nielsen J, and Leiserowitz L

Subjects
Cells, Cultured, Crystallization, Erythrocytes parasitology, Heme metabolism, Hemeproteins metabolism, Hemoglobins metabolism, Humans, Iron metabolism, Kinetics, Microscopy methods, Plasmodium falciparum metabolism, Plasmodium falciparum ultrastructure, Spectrometry, X-Ray Emission methods, Vacuoles metabolism, Vacuoles ultrastructure, X-Ray Microtomography methods, Heme chemistry, Hemeproteins chemistry, Hemoglobins chemistry, Iron chemistry, Models, Chemical, Plasmodium falciparum chemistry, Vacuoles chemistry
Abstract

A key drug target for malaria has been the detoxification pathway of the iron-containing molecule heme, which is the toxic byproduct of hemoglobin digestion. The cornerstone of heme detoxification is its sequestration into hemozoin crystals, but how this occurs remains uncertain. We report new results of in vivo rate of heme crystallization in the malaria parasite, based on a new technique to measure element-specific concentrations at defined locations in cell ultrastructure. Specifically, a high resolution correlative combination of cryo soft X-ray tomography has been developed to obtain 3D parasite ultrastructure with cryo X-ray fluorescence microscopy to measure heme concentrations. Our results are consistent with a model for crystallization via the heme detoxification protein. Our measurements also demonstrate the presence of considerable amounts of non-crystalline heme in the digestive vacuole, which we show is most likely contained in hemoglobin. These results suggest a tight coupling between hemoglobin digestion and heme crystallization, highlighting a new link in the crystallization pathway for drug development.

Published
2017
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54. Accurate charge densities from powder X-ray diffraction - a new version of the Aarhus vacuum imaging-plate diffractometer.

Author

Tolborg K, Jørgensen MRV, Christensen S, Kasai H, Becker J, Walter P, Dippel AC, Als-Nielsen J, and Iversen BB

Abstract

In recent years powder X-ray diffraction has proven to be a valuable alternative to single-crystal X-ray diffraction for determining electron-density distributions in high-symmetry inorganic materials, including subtle deformation in the core electron density. This was made possible by performing diffraction measurements in vacuum using high-energy X-rays at a synchrotron-radiation facility. Here we present a new version of our custom-built in-vacuum powder diffractometer with the sample-to-detector distance increased by a factor of four. In practice this is found to give a reduction in instrumental peak broadening by approximately a factor of three and a large improvement in signal-to-background ratio compared to the previous instrument. Structure factors of silicon at room temperature are extracted using a combined multipole-Rietveld procedure and compared with ab initio calculations and the results from the previous diffractometer. Despite some remaining issues regarding peak asymmetry, the new diffractometer yields structure factors of comparable accuracy to the previous diffractometer at low angles and improved accuracy at high angles. The high quality of the structure factors is further assessed by modelling of core electron deformation with results in good agreement with previous investigations.

Published
2017
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55. X-ray Experiments for Students at the SLS Optics Beamline.

Author

Flechsig, U., Als-Nielsen, J., Jaggi, A., Krempaský, J., Oberta, P., Spielmann, S., and van der Veen, J. F.

Subjects
*X-ray optics, *SYNCHROTRON radiation, *ELECTROMAGNETIC waves, *SYNCHROTRONS, *CALORIMETERS
Abstract

We present a X-ray training course for students. The course covers fundamental properties of synchrotron radiation and basic techniques like scattering and absorption. We prepared ten experiments together with a tutorial. The whole course takes about a week. A first student group from the University of Copenhagen passed the course in June 2009. The experiments were performed at the optics beamline of the Swiss Light Source which can be part-time allocated for training purposes. Two experiments are described in more detail: scattering from a hanging drop of water turning into ice and measurement of the power of a pink synchrotron beam using a simple calorimeter. [ABSTRACT FROM AUTHOR]

Published
2010
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57. The “Pile-up Effect” in Photon Detection.

Author

Madsen, A., Als-Nielsen, J., Zontone, F., Grübel, G., and Warwick, T.

Subjects
*X-rays, *ELECTROMAGNETIC waves, *RADIATION, *ELECTRON spectroscopy, *SYNCHROTRON radiation, *PARTICLES (Nuclear physics), *SYNCHROTRONS
Abstract

We quantify the pile-up of X-ray photons in a single-photon-counting detector with finite dead-time when subject to an intense synchrotron beam of non-Poisson distributed photons. The pile-up leads to a non-linearity between the registered count-rate and the true photon-rate when a single-channel analyzer is employed and we show that the phenomenon can be described by use of a simple statistical model. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2004
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68. High-Q-resolution X-ray diffraction of ordered Fe–Al single crystals

Author

Bley, F., primary, Livet, F., additional, Leroux, J. C., additional, Simon, J. P., additional, Abernathy, D., additional, Als-Nielsen, J., additional, Gruebel, G., additional, Vignaud, G., additional, Dolino, G., additional, Legrand, J. F., additional, Camel, D., additional, Menguy, N., additional, and Papoular, M., additional

Published
1995
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70. STRUCTURAL BASIS OF CELL-CELL ADHESION BY CADHERINS

Author

Shapiro, L., primary, Fannon, A.M., additional, Kwong, P.D., additional, Thompson, A., additional, Lehmann, M.S., additional, Grubel, G., additional, Legrand, J.-F., additional, Als-Nielsen, J., additional, Colman, D.R., additional, and Hendrickson, W.A., additional

Published
1995
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77. First test of the scanning X-ray microprobe with Bragg-Fresnel multilayer lens at ESRF beam line

Author

Chevallier, P., primary, Dhez, P., additional, Legrand, F., additional, Idir, M., additional, Soullie, G., additional, Mirone, A., additional, Erko, A., additional, Snigirev, A., additional, Snigireva, I., additional, Suvorov, A., additional, Freund, A., additional, Engström, P., additional, Als Nielsen, J., additional, and Grübel, A., additional

Published
1995
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96. X-ray scattering studies of fatty acid films on water and on Cdcl2 solutions

Author

Kjaer, K., primary, Als-Nielsen, J., additional, Kenn, R. M., additional, Böhm, C., additional, Tippmann-Krayer, P., additional, Peterson, I. R., additional, Bibo, A. M., additional, Helm, C. A., additional, Möhwald, H., additional, Leveiller, F., additional, Jacquemain, D., additional, Weinbach, S., additional, Leiserowitz, L., additional, and Deutsch, M., additional

Published
1991
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