Design, Quality Control and Normalization of Biosensor Chips

  • Claudia Preininger
  • Ursula Sauer
Part of the Springer Series on Chemical Sensors and Biosensors book series (SSSENSORS, volume 1)


With the completion of the human genome project biochip technologies have boosted and revolutionized automated genomic and proteomic analysis (; [1–7]. Based on conventional biomolecular techniques such as Southern and Northern blotting, sample preparation and assay was miniaturized by micromachining and microbiochemistry implemented efficiently by automated processes. To use biochip technologies for high throughput applications the system was adapted for high levels of parallelization. The potential of biochips lies in the parallel analysis of a huge number of probes, measured at once instead of one probe after the other. Such a technique speeds up biomolecular analysis tremendously. DNA chips have been widely used for gene expression, functional analysis, gene mapping and genotyping. Measuring RNA levels, however, might not give a complete or accurate description of a biological system. Because proteins mediate nearly all cellular activities, biochips have also been applied at the protein level (“proteomics”) [8, 9].


Fluorescence Resonance Energy Transfer Oligonucleotide Array Chip Surface Chip Analysis Glass Chip 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 1.
    Schena M (ed) (1999) DNA Microarrays: a practical approach. Oxford University PressGoogle Scholar
  2. 2.
    Case-Green SC, Mir KU, Pritchard CE, Southern EM (1998) Analysing genetic information with DNA arrays. Curr Opin Chem Biol 2: 404 - 410CrossRefGoogle Scholar
  3. 3.
    Wang J (2000) From DNA biosensors to gene chips. Nucl Acid Res 28: 3011 - 3016CrossRefGoogle Scholar
  4. 4.
    Sanders GHW, Manz A (2000) Chip-based microsystems for genomic and proteomic analysis. Trends Anal Chem 19: 364 - 378CrossRefGoogle Scholar
  5. 5.
    Lockhart DJ, Winzeler EA (2000) Genomics, gene expression and DNA-arrays. Nature 405: 827 - 836CrossRefGoogle Scholar
  6. 6.
    Kurian KM, Watson CJ, Wyllie AH (1999) DNA chip technology. J Pathol 187: 267 - 271CrossRefGoogle Scholar
  7. 7.
    Vo-Dinh T, Cullum BM, Stokes DL (2001) Nanosensors and biochips: frontiers in bio-molecular diagnostic. Sens Actuators B 74: 2 - 11CrossRefGoogle Scholar
  8. 8.
    Weinberger SR, Morris TS, Pawlak M (2000) Recent trends in protein biochip technology. Pharmacogenomics 1: 395 - 416CrossRefGoogle Scholar
  9. 9.
    Mirzabekov A, Kolchinsky A (2001) Emerging array-based technologies in proteomics. Curr Opin Biotechnol 6: 70 - 75Google Scholar
  10. 10.
    Vo-Dinh T, Alarie JP, Isola N, Landis D, Winterberg AL, Ericson MN (1999) DNA Biochip Using a Phototransistor Integrated Circuit. Anal Chem 71: 358 - 363CrossRefGoogle Scholar
  11. 11.
    Iqbal SS, Mayo MW, Bruno JG, Bronk BV, Batt CA, Chambers JP (2000) A review of molecular technologies for detection of biological threat agents. Biosens Bioelectron 15: 549 - 578CrossRefGoogle Scholar
  12. 12.
    van Hal NLW, Vorst O, van Houwelingen AMML, Kok EJ, Peijnenburg A, Aharoni A, van Tunen AJ, Keijer J (2000) The application of DNA microarrays in gene Expression analysis. J Biotechnol 78: 271 - 280CrossRefGoogle Scholar
  13. 13.
    Kuipers OP (1999) Genomics for food biotechnology: prospects of the use of high-throughput technologies for the improvement of food microorganisms. Curr Opin Biotech 10: 511 - 516CrossRefGoogle Scholar
  14. 14.
    Wu L, Thompson DK, Guangshan L, Hurt RA, Tiedje JM, Zhou J (2001) Development and Evaluation of Functional Gene Arrays for Detection of Selected Genes in the Environment. App Environ Microbiol 67: 5780 - 5790CrossRefGoogle Scholar
  15. 15.
    Guschin DY, Mobarry BK, Proudnikov D, Stahl DA, Rittmann BE, Mirzabekov AD (1997) Oligonucleotide Microchips as Genosensors for Determinative and Environmental Studies in Microbiology. App Environ Microbiol 63: 2397 - 2402Google Scholar
  16. 16.
    Bodrossy L (2003) Diagnostic oligonucleotide microarrays for microbiology. In: Blalock E (ed): Microarrays and Bioinformatics for Beginners. Kluwer Academic Publishers, New York. In Press.Google Scholar
  17. 17.
    Nuwaysir EF, Bittner M, Trent J, Barrett JC, Afshari CA (1999) Microarrays and toxicology: the advent of toxicogenomics. Mol Carcinog 24: 153 - 159CrossRefGoogle Scholar
  18. 18.
    Barzen B, Brecht A, Gauglitz G (2002) Optical multiple-analyte immunosensor for water pollution control. Biosens Bioelectron 17: 289 - 295CrossRefGoogle Scholar
  19. 19.
    Weller MG, Schuetz AJ, Winklmair M, Niessner R (1999) Highly parallel affinity sensor for the detection of environmental contaminants in water. Anal Chim Acta 393: 29 - 41CrossRefGoogle Scholar
  20. 20.
    Shimomura M, Nomura Y, Zhang W, Sakino M, Lee K-H, Ikebukuro K, Karube I (2001) Simple and rapid detection method using surface plasmon resonance for dioxins, polychlorinated biphenyls and atrazine. Anal Chim Acta 434: 223 - 230CrossRefGoogle Scholar
  21. 21.
    Rowe-Taitt CA, Golden JP, Feldstein MJ, Cras JJ, Hoffman KE, Ligler FS (2000) Array biosensor for detection of biohazards. Biosens Bioelectron 14: 785 - 794CrossRefGoogle Scholar
  22. 22.
    Rowe CA, Tender LM, Feldstein MJ, Golden JP, Scruggs SB, MacCraith BD, Cras JJ, Ligler FS (1999) Array Biosensor for Simultaneous Identification of Bacterial, Viral, and Protein Analytes. Anal Chem 71: 3846-3852Google Scholar
  23. 23.
    Taylor LC, Walt DR (2000) Application of High-Density Optical Microwell arrays in a Live-Cell Biosensing System. Anal Biochem 278: 132 - 142CrossRefGoogle Scholar
  24. 24.
    Christensen CBV (2002) Arrays in biological and chemical analysis Talanta 56:289299Google Scholar
  25. 25.
    Hacia JG (1999) Resequencing and mutational analysis using oligonucleotide micro-arrays. Nature Genetics Suppl 21: 42 - 47CrossRefGoogle Scholar
  26. 26.
    Leuking A, Horn M, Eickhoff H, Buessow K, Lehrach H and Walter (1999) G Protein microarrays for gene expression and antibody screening. Anal Biochem 270: 103 - 111CrossRefGoogle Scholar
  27. 27.
    MacBeath G, Schreiber SL (2000) Printing proteins as microarrays for high-throughput function determination. Science 289: 1760 - 1763Google Scholar
  28. 28.
    Schweitzer B, Kingsmore SF, Measuring proteins on microarrays (2002) Curr Opin Biotechnol 13: 14 - 19CrossRefGoogle Scholar
  29. 29.
    Lowe CR, Chemoselective biosensors. (1999) Curr Opin Chem Biol 3: 106 - 111CrossRefGoogle Scholar
  30. 30.
    Fodor SPA, Read JL, Pirrung MC, Stryer L, Lu AT, Solas D (1991) Light-directed, spatially addressable parallel chemical synthesis. Science 251: 767 - 773CrossRefGoogle Scholar
  31. 31.
    Southern EM, Maskos U, Elder JK (1992) Analyzing and comparing nucelic acid sequences by hybridization to arrays of oligonucleotides: evaluation using experimental models. Genomics 13: 1008 - 1017CrossRefGoogle Scholar
  32. 32.
    Beier M, Hoheisel JD (2000) Production by quantitative photolithographic synthesis of individually quality checked DNA microarrays. Nucl Acid Res 28:el1Google Scholar
  33. 33.
    Zhai JY, Wang C. Making DNA microarrays on glass slides, Axon Instr, Google Scholar
  34. 34.
    Stillman BA, Tonkinson JL (2000) FAST Slides: a novel surface for microarrays. Bio-Techniques 29: 630 - 35Google Scholar
  35. 35.
    Beier M, Hoheisel JD (1999) Versatile derivatization of solid support media for covalent bonding on DNA-microchips. Nucl Acid Res 27: 1970 - 77CrossRefGoogle Scholar
  36. 36.
    Vassiliskov AV, Timofeev EN, Surzhikov SA, Drobyshev AL, Shick VV, Mirzabekov AD (1999) Fabrication of microarray of gel-immobilized compounds on a chip by copolymerization. BioTechniques 27: 592 - 606Google Scholar
  37. 37.
    Preininger C, Chiarelli P (2001) Immobilization of Oligonucleotides on Crosslinked Poly(vinyl alcohol) for Application in DNA chips. Talanta 55: 973 - 980CrossRefGoogle Scholar
  38. 38.
    Kumar A, Larsson O, Parodi D, Liang Z (2000) Silanized nucleic acids: a general platform for DNA immobilization. Nucl Acid Res 28: e71Google Scholar
  39. 39.
    Rehman FN, Audeh M, Abrams ES, Hammond PhW, Kenney M, Boles TC (1999) Immobilzation of acrylamide-modified oligonucleotides by co-polymerization. Nucl Acid Res 27: 649 - 655CrossRefGoogle Scholar
  40. 40.
    Raddatz S, Mueller-Ibeler J, Kluge J, Wäß L, Burdinski G, Havens JR, Onofrey TJ, Wang D, Schweitzer M (2002) Hydrazide oligonucleotides: new chemical modification for chip array attachment and conjugation. Nucl Acid Res 30: 4793 - 4802CrossRefGoogle Scholar
  41. 41.
    Zhao X, Nampalli, Serino AJ, Kumar S (2001) Immobilization of oligonucleotides with multiple anchors to microchips. Nucl Acid Res 29: 955 - 959CrossRefGoogle Scholar
  42. 42.
    Livache T, Fouque B, Roget A, Marchand J, Bidan G, Téoule R, Mathis G (1998) Polypyrrole DNA-chip on a silicon device. Anal Biochem 255: 188 - 194CrossRefGoogle Scholar
  43. 43.
    Beaucage SL (2001) Strategies in the preparation of DNA oligonucleotide arrays for diagnostic applications. Curr Med Chem 8: 1213 - 44CrossRefGoogle Scholar
  44. 44.
    Miyachi H, Hiratsuka A, Ikebukuro K, Yano K, Muguruma H, Karube I (2000) Application of polymer-ambedded proteins to fabrication of DNA array. Biotechnol Bioeng 69: 323 - 329CrossRefGoogle Scholar
  45. 45.
    Zammatteo N, Jeanmart L, Hamels S, Courtois S, Louette P, Hevesi L, Remade J (2000) Comparison between different strategies of covalent attachment of DNA to glass surfaces to build microarrays. Anal Biochem 280: 143 - 150CrossRefGoogle Scholar
  46. 46.
    Rogers YH, Jiang-Baucom P, Huang ZJ, Bogdanov V, Anderson S, Boyce-Jacino MT (1999) Immobilization of Oligonucleotides onto Glass Support via Disulfide Bonds: a Method for Preparation of DNA Microarrays. Anal Biochem 266: 23CrossRefGoogle Scholar
  47. 47.
    Jung A, Stemmler I, Brecht A, Gauglitz G (2001) Covalent immobilisation strategy of DNA-microspots suitable for microarrays with label-free and time-resolved optical detection of hybridisation. Fres J Anal Chem 371: 128 - 136CrossRefGoogle Scholar
  48. 48.
    Lindroos K, Liljedahl U, Raitio M, Syvänen A (2001) Minisequencing on oligonucleotide microarrays: comparision of immobilisation chemistries. Nucl Acid Res 29: e69Google Scholar
  49. 49.
    Dolan PL, Wu Y, Ista LK, Metzenberg RL, Nelson MA, Lopez GP (2001) Robust and efficient synthetic method for forming DNA microarrays. Nucl Acid Res 29: e107Google Scholar
  50. 50.
    Benters R, Niemeyer CM, Drutschmann D, Blohm D, Wöhrle D (2002) DNA microarrays with PAMPAM dendritic linker systems. Nucl Acid Res 30: e10Google Scholar
  51. 51.
    Sung JC, Chang KO, Joon PW (2002) Characteristics of DNA microarrays fabricated on various aminosilane layers. Langmuir 18: 1764 - 1769CrossRefGoogle Scholar
  52. 52.
    Wu LL, Zhou JZ, Luo J, Lin ZH (2000) Electrochim Acta 45: 2923CrossRefGoogle Scholar
  53. 53.
    Southern E, Mir K, Shchepinov M (1999) Molecular interactions on microarrays. Nature Gen Suppl 21: 5CrossRefGoogle Scholar
  54. 54.
    Steel AB, Levicky RL, Herne TM, Tarlov MJ (2000) Immobilization of nucleic acids at solid surfaces: effect of oligonucleotide length on layer assembly. Biophys J 79: 975981Google Scholar
  55. 55.
    Kodadek T (2001) Protein microarrays: prospects and problems. Chem Biol 8: 105115Google Scholar
  56. 56.
    Schaeferling M, Schiller S, Paul H, Kruschina M, Pavlickova P, Meerkamp M, Giammasi M, Kambhampati D (2002) Application of self-assembly techniques in the design of biocompatible protein microarray surfaces. Electrophor 23: 3097 - 3105CrossRefGoogle Scholar
  57. 57.
    Angenendt P, Glökler J, Murphy D, Lehrach H, Cahill DJ (2002) Toward optimized antibody microarrays: a comparison of current microarray support materials. Anal Biochem 309: 253 - 260CrossRefGoogle Scholar
  58. 58.
    Piehler J, Brecht A, Valiokas R, Liedberg B, Gauglitz G (2000) A high-density poly(ethylene glycol) polymer brush for immobilization on glass-typer surfaces. Bio-sens Bioelectr 15: 473 - 481CrossRefGoogle Scholar
  59. 59.
    Birkert O, Haake H-M, Schuetz A, Mack J, Brecht A, Jung G, Gauglitz G (2000) A streptavidin surface on planar glass substrates for the detection of biomolecular interaction. Anal Biochem 282: 200 - 208CrossRefGoogle Scholar
  60. 60.
    Akkoyun A, Bilitewski U (2002) Optimisation of glass surfaces for optical immunosensors. Biosens Bioelectr 17: 655 - 664CrossRefGoogle Scholar
  61. 61.
    Schneider BH, Dickinson EL, Vach MD, Hoijer JV, Howard LV (2000) Highly sensitive optical chip immunoassays in human serum. Biosens Bioelectron 15: 13 - 22CrossRefGoogle Scholar
  62. 62.
    Eickhoff H, Schürenberg M, Nordhoff E (2001) 2D/3D-BioChips-Neue Werkzeuge für die funktionelle Genom-und Proteomanalyse. Transkript Nr.IIIGoogle Scholar
  63. 63.
    Cheung VG, Morley M, Aguilar F, Massimi A, Kucherlapati R, Childs G (1999) Making and reading microarrays. Nature Genet 21: 15 - 19CrossRefGoogle Scholar
  64. 64.
    Liebermann T, Knoll W (2000) Surface-plasmon field-enhanced fluorescence spectroscopy. Colloids Surfaces A 171: 115 - 130CrossRefGoogle Scholar
  65. 65.
    Piehler J, Brecht A, Gauglitz G, Zerlin M, Maul C, Thiercke R, Grabley S (1997) Label-free monitoring of DNA-ligand interactions. Anal Biochem 249: 94 - 102CrossRefGoogle Scholar
  66. 66.
    Sauer M, Brecht A, Charissé K, Maier M, Gerster M, Stemmler I, Gauglitz G, Bayer E (1999) Interaction of Chemically Modified Antisense Oligonuceotides with Sense DNA: A Label Free Interaction Study with Reflectometric Interference Spectroscopy. Anal Chem 71: 2850-2857Google Scholar
  67. 67.
    Mayer C, Stich N, Palkovits R, Bauer G, Pittner F, Schalkhammer T (2001) Highthrougput assays on the chip based on metal nano-cluster resonance transducers. J Pharmac Biomed Analysis 24: 773 - 783CrossRefGoogle Scholar
  68. 68.
    Taylor JR, Fang MM, Nie S (2000) Probing specific sequences on single DNA molecules with bioconjugated fluorescent nanoparticles. Anal Chem 72: 1979 - 1986CrossRefGoogle Scholar
  69. 69.
    Köhler JM, Csaki A, Reichert J, Möller R, Straube W, Fritzsche W (2001) Selective labeling of oligonucleotide monolayers by metallic nanobeads for fast optical readout of DNA-chips. Sens Act B 76: 166 - 172CrossRefGoogle Scholar
  70. 70.
    Taton TA, Lu G, Mirkin CA (2001) Two-Color Labeling of Oligonucleotide Arrays via Size-Selective Scattering of Nanoparticle Probes. J Am Chem Soc 123: 5164 - 65CrossRefGoogle Scholar
  71. 71.
    Taton TA, Mirkin CA, Letsinger RL (2000) Scanometric DNA array detection with nanoparticle probes. Science 289: 1757 - 1760CrossRefGoogle Scholar
  72. 72.
    Han M, Gao X, Su JZ, Nie S (2001) Quantum-dot-tagged microbeads for multiplexed optical coding of biomolecules. Nature Biotechnol 19: 631 - 635CrossRefGoogle Scholar
  73. 73.
    Chan WC, Nie SM (1998) Quantum dot bioconjugates for ultrasensitive nonisotopic detection. Science 281: 2016 - 2018CrossRefGoogle Scholar
  74. 74.
    Mitchell GP, Mirkin CA, Letsinger RL (1999) Programmed assembly of DNA functionalized quantum dots. J Am Chem Soc 121: 8122 - 8123CrossRefGoogle Scholar
  75. 75.
    Pathak S, Choi SK, Arnheim N Thompson ME (2001) Hydroxylated quantum dots as luminescent probes for in situ hybridization. J Am Chem Soc 123: 4103 - 4104CrossRefGoogle Scholar
  76. 76.
    Preininger C, Sauer U (2003) Quality control of chip manufacture and chip analysis using epoxy-chips as a model. Sens Actuators B, 90: 98 - 103CrossRefGoogle Scholar
  77. 77.
    Quackenbush J (2001) Computational Analysis of Microarray Data. Nature Reviews Genetics 2: 418 - 427CrossRefGoogle Scholar
  78. 78.
    Colantuoni C, Henry G, Zeger S, Pevsner S (2002) SNOMAD ( Standardization and NOrmalization of MicroArray Data ): Web-accessible Gene Expression Data Analysis. Bioinformatics 18: 1540-1541Google Scholar
  79. 79.
    Sanchez-Carbayo M, Bornmann W, Cordon-Cardo C (2000) DNA Microchips: Technical and Practical Considerations. Current Organic Chemistry 4: 945-971Google Scholar
  80. 80.
    Aharoni A, Vorst 0 (2001) DNA microarrays for functional plant genomics. Plant Mol Biol48: 99 - 118Google Scholar
  81. 81.
    Tran PH, Pfeiffer DA, Shin Y, Meek LM, Brody JP, Cho KWY (2002) Microarray optimizations: increasing spot accuracy and automated identification of true microarray signals. Nucl Acid Res 30: e54Google Scholar
  82. 82.
    Kane MD, Jatkoe TA, Stumpf CR, Lu J, Thomas JD, Madore SJ (2000) Assessment of the sensitivity and specificity of oligonucleotide (50mer) microarrays. Nucl Acid Res 28: 4552 - 4557CrossRefGoogle Scholar
  83. 83.
    Khan J, Saal LH, Bittner ML, Chen Y, Trent JM, Meltzer PS (1999) Expression profiling in cancer using cDNA microarrays. Electrophoresis 20: 223 - 229CrossRefGoogle Scholar
  84. 84.
    Urakawa H, Noble PA, El Fantroussi S, Kelly JJ, Stahl DA (2002) Single-Base-Pair Discrimination of Terminal Mismatches by Using Oligonucleotide Microarrays and Neural Network Analyses. Appl Environ Microbiol 68: 235 - 244CrossRefGoogle Scholar
  85. 85.
    Schuchhardt J, Beule D, Malik A, Wolsji E, Eickhoff H, Lehrach H, Herzel H (2000) Normalization strategies for cDNA microarrays. Nucl Acid Res 28: e47Google Scholar
  86. 86.
    Hegde P, Qi R, Abernathy K, Gay C, Dharap S, Gaspard R, Earle Hughes J, Snesrud E, Lee N, Quackenbush J (2000) A Concise Guide to cDNA Microarray Analysis. Biotechniques 29: 548 - 562Google Scholar
  87. 87.
    Yang YH, Dudoit S, Luu P, Lin DM, Peng V, Ngai J, Speed T (2002) Normalization for cDNA microarray data: a robust composite method addressing single and multiple slide systematic variation. Nucl Acid Res 30: e15Google Scholar
  88. 88.
    Kerr MK, Mitchell M, Churchill GA (2000) Analysis of Variance for Gene Expression Microarray Data. J Computat Biol 7: 819 - 837CrossRefGoogle Scholar
  89. 89.
    Raychaudhuri S, Sutphin PD, Chang JT, Altman RB (2001) Basic microarray analysis: grouping and feature reduction. Trends Biotechnol 19: 189 - 193CrossRefGoogle Scholar
  90. 90.
    Brazma A, Vilo J (2000) Gene expression data analysis. FEBS Letters 480: 17 - 24CrossRefGoogle Scholar
  91. 91.
    Lönnstedt I, Speed TP (2002) Replicated Microarray Data. Statistica Sinica 12: 31 - 46Google Scholar
  92. 92.
    Long AD, Mangalam HJ, Chan BYP, Tolleri L, Hatfield GW, Baldi P (2001) Improved Statistical Inference from DNA Microarray Data Using Analysis of Variance and A Bayesian Statistical Framework. J Biol Chem 276: 19937 - 19944CrossRefGoogle Scholar
  93. 93.
    Alon U, Barkai N, Notterman DA, Gish K, Ybarra S, Mack D, Levine AJ (1999) Broad patterns of gene expression revealed by clustering analysis of tumor and normal colon tissues probed by oligonucleotide arrays. Proc Natl Acad Sci 96: 6745 - 6750CrossRefGoogle Scholar
  94. 94.
    Kerr MK, Churchill GA (2001) Bootstrapping cluster analysis: Assessing the reliability of conclusions from microarray experiments. Proc Natl Acad Sci 98: 8961-8965Google Scholar
  95. 95.
    Eisen MB, Spellman PT, Brown PO, Botstein D (1998) Cluster analysis and display of genome-wide expression patterns. Proc Natl Acad Sci 95: 14863 - 14868CrossRefGoogle Scholar
  96. 96.
    Golub TR, Slonim DK, Tamayo P, Huard C, Gaasenbek M, Mesirov JP, Coller H, Loh ML, Downing JR, Caligiuri MA, Bloomfield CD, Lander ES (1999) Molecular classification of cancer: class discovery and class prediction by gene expression monitoring. Science 286: 531 - 7CrossRefGoogle Scholar
  97. 97.
    Tavazoie S, Hughes JD, Campell MJ, Cho RJ, Church GM (1999) Systematic determination of genetic network architecture. Nature Genet 22: 281 - 285CrossRefGoogle Scholar
  98. 98.
    Herrero J, Valencia A, Dopazo J (2001) A hierarchical unsupervised growing neural network for clustering gene expression patterns. Bioinformatics 17: 126 - 136CrossRefGoogle Scholar
  99. 99.
    Chu T, Weir B, Wolfinger R (2002) A systematic statistical linear modeling approach to oligonucleotide array experiments. Math Biosci 176: 35 - 51CrossRefGoogle Scholar
  100. 100.
    Jain AN, Tokuyasu TA, Snijders AM, Segraves R, Albertson DG, Pinkel D (2002) Fully Automatic Quantification of Microarray Image Data. Genome Res 12: 325 - 332CrossRefGoogle Scholar
  101. 101.
    Getz G, Levine E, Domany E (2000) Coupled two-way clustering analysis of gene microarray data. Proc Natl Acad Sci 97: 12079 - 12084CrossRefGoogle Scholar

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© Springer-Verlag Berlin Heidelberg 2004

Authors and Affiliations

  • Claudia Preininger
  • Ursula Sauer

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