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Khun, Kimleang
Publications (10 of 23) Show all publications
Elhag, S., Khun, K., Khranovskyy, V., Liu, X., Willander, M. & Nour, O. (2016). Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties. Sensors, 16(2)
Open this publication in new window or tab >>Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties
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2016 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 2Article in journal (Refereed) Published
Abstract [en]

In this paper, we show that the possibility of using polyethylene glycol (EG) as a hydrogen source and it is used to assist the hydrothermal synthesis of ZnO nanorods (ZNRs). EG doping in ZNRs has been found to significantly improve their optical and chemical sensing characteristics toward glutamate. The EG was found to have no role on the structural properties of the ZNRs. However, the x-ray photoelectron spectroscopy (XPS) suggests that the EG could induce donor impurities effect in ZnO. Photoluminescence (PL) and UV-Vis. spectra demonstrated this doping effect. Mott-Schottky analysis at the ZNRs/electrolyte interface was used to investigate the charge density for the doped ZNRs and showed comparable dependence on the used amount of EG. Moreover, the doped ZNRs were used in potentiometric measurements for glutamate for a range from 10(-6) M to 10(-3) M and the potential response of the sensor electrode was linear with a slope of 91.15 mV/decade. The wide range and high sensitivity of the modified ZNRs based glutamate biosensor is attributed to the doping effect on the ZNRs that is dictated by the EG along with the high surface area-to-volume ratio. The findings in the present study suggest new avenues to control the growth of n-ZnO nanostructures and enhance the performance of their sensing devices.

Place, publisher, year, edition, pages
MDPI AG, 2016
Keywords
potentiometric sensor; ZnO nanorods; glutamate; doping
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-126849 (URN)10.3390/s16020222 (DOI)000371787800096 ()26861342 (PubMedID)
Note

Funding Agencies|University of Kordofan, El-Obeid, Kordofan Sudan [700]

Available from: 2016-04-05 Created: 2016-04-05 Last updated: 2017-11-30
Khun, K., Elhag, S., Ibupoto, Z. H., Khranovskyy, V., Nur, O. & Willander, M. (2015). Supramolecules-assisted ZnO nanostructures growth and their UV photodetector application. Solid State Sciences, 41, 14-18
Open this publication in new window or tab >>Supramolecules-assisted ZnO nanostructures growth and their UV photodetector application
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2015 (English)In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 41, p. 14-18Article in journal (Refereed) Published
Abstract [en]

Zinc oxide (ZnO) nanosheets, nickel oxide (NiO) nanoflowers and their nanocomposite were grown on the fluorine doped tin oxide (FTO) substrate. The supramolecules-assisted ZnO growth by a hydrothermal method used to tune the morphology of the grown ZnO nanostructures to nanosheets morphology. The synthesis, purity and the optical properties of the grown material were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), UV-visible spectrometry and photoluminescence (PL) analysis. The current-voltage (I-V) characterization of the ZnO/NiO heterojunction was performed at room temperature and showed an obvious nonlinear and rectifying response. A strong UV absorption with fast switching was observed from the ZnO/NiO composite heterojunction. The proposed UV photodetector based on this nano-composite is more stable, possesses fast rising and decaying time response approximately 100 ms and low leakage current was investigated. The findings indicate that the importance of the use of controlled nanostructures morphology for developing efficient nanodevices for various applications

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
ZnO/NiO nano-composite; UV absorption ZnO; nano-heterojunction; UV photodetector
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-112863 (URN)10.1016/j.solidstatesciences.2015.01.011 (DOI)000350888800003 ()
Note

On the day of the defence date the status of this article was Manuscript.

Available from: 2014-12-18 Created: 2014-12-18 Last updated: 2017-12-05Bibliographically approved
Khun, K., Ibupoto, Z. H., Liu, X., Beni, V. & Willander, M. (2015). The ethylene glycol template assisted hydrothermal synthesis of Co3O4 nanowires; structural characterization and their application as glucose non-enzymatic sensor. Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, 194, 94-100
Open this publication in new window or tab >>The ethylene glycol template assisted hydrothermal synthesis of Co3O4 nanowires; structural characterization and their application as glucose non-enzymatic sensor
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2015 (English)In: Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, ISSN 0921-5107, E-ISSN 1873-4944, Vol. 194, p. 94-100Article in journal (Refereed) Published
Abstract [en]

In the work reported herein the ethylene glycol template assisted hydrothermal synthesis, onto Au substrate, of thin and highly dense cobalt oxide (Co3O4) nanowires and their characterization and their application for non-enzymatic glucose sensing are reported. The structure and composition of Co3O4 nanowires have been fully characterized using scanning electron microscopy, X-ray diffraction, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The synthesized Co3O4 nanowires resulted to have high purity and showed diameter of approximately 10 nm. The prepared Co3O4 nanowires coated gold electrodes were applied to the non-enzymatic detection of glucose. The developed sensor showed high sensitivity (4.58 x 10(1) mu A mM(-1) cm(-2)), a wide linear range of concentration (1.00 x 10(-4)-1.2 x 10(1) mM) and a detection limit of 2.65 x 10(-5) mM. The developed glucose sensor has also shown to be very stable and selective over interferents such as uric acid and ascorbic acid. Furthermore, the proposed fabrication process was shown to be highly reproducible response (over nine electrodes).

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Non-enzymatic glucose sensor; Co3O4 nanowires; Template assisted hydrothermal synthesis; Amperometry; Ethylene glycol
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Biological Sciences
Identifiers
urn:nbn:se:liu:diva-116815 (URN)10.1016/j.mseb.2015.01.001 (DOI)000350091600014 ()
Note

Funding Agencies|International Science Programme (IPPS), Uppsala University, Sweden [CAM:01]; Royal University of Phnom Penh (RUPP), Cambodia

Available from: 2015-04-07 Created: 2015-04-07 Last updated: 2017-12-04
Ibupoto, Z. H., Khun, K., Liu, X. & Willander, M. (2014). A Potentiometric Biosensor for the Detection of Notch 3 Using Functionalized ZnO Nanorods. Journal of Nanoscience and Nanotechnology, 14(9), 6704-6710
Open this publication in new window or tab >>A Potentiometric Biosensor for the Detection of Notch 3 Using Functionalized ZnO Nanorods
2014 (English)In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6704-6710Article in journal (Refereed) Published
Abstract [en]

The notch signalling plays a vital and radical role for the activity of cellular proliferation, differentiation and apoptosis. In this study, for the first time a particular biosensor is developed for the detection of notch 3. ZnO nanorods were fabricated on the gold coated glass substrate by hydrothermal method and afterwards were decorated with the gold nanoparticles by electrodepositing technique. Scanning electron microscopy (SEM) has shown the perpendicular to the substrate growth pattern of ZnO nanorods. X-ray diffraction (XRD) studies showed the c-axis oriented growth direction with wurtzite crystal structure of ZnO nanorods. X-ray Photoelectron Spectroscopy (XPS) and energy dispersive X-ray (EDX) techniques have shown the presence of Zn, O and Au atoms in the prepared functional material. Furthermore, the anti-notch 3 was physically adsorbed on the gold nanoparticles functionalized ZnO nanorods. The developed potentiometric immunosensor has shown response to the wide range of notch 3 molecules. The detected range included 1.00 x 10(-5)-1.50 x 10(0) mu g/mL with a sensitivity of 23.15 +/- 0.31 mV/decade. The analytical parameters including reproducibility, stability, and selectivity were also investigated and the observed results indicate the acceptable performance of the notch 3 biosensor. Moreover, the proposed notch 3 biosensor exhibited a fast response time of 10 s.

Place, publisher, year, edition, pages
American Scientific Publishers, 2014
Keywords
Gold Nanoparticles; ZnO Nanorods; Potentiometric Technique; Immunosensor; Anti-Notch 3; Notch 3 of Human
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-107434 (URN)10.1166/jnn.2014.9374 (DOI)000335873900029 ()
Available from: 2014-06-12 Created: 2014-06-12 Last updated: 2017-12-05Bibliographically approved
Khun, K., Ibupoto, Z. H., Liu, X., Nur, O., Willander, M. & Danielsson, B. (2014). A Selective Potentiometric Copper (II) Ion Sensor Based on the Functionalized ZnO Nanorods. Journal of Nanoscience and Nanotechnology, 14(9), 6723-6731
Open this publication in new window or tab >>A Selective Potentiometric Copper (II) Ion Sensor Based on the Functionalized ZnO Nanorods
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2014 (English)In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6723-6731Article in journal (Refereed) Published
Abstract [en]

In this work, ZnO nanorods were hydrothermally grown on the gold-coated glass substrate and characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques. The ZnO nanorods were functionalized by two different approaches and performance of the sensor electrode was monitored. Fourier transform infrared spectroscopy (FTIR) was carried out for the confirmation of interaction between the ionophore molecules and ZnO nanorods. In addition to this, the surface of the electrode was characterized by X-ray photoelectron spectroscopy (XPS) showing the chemical and electronic state of the ionophore and ZnO nanorod components. The ionophore solution was prepared in the stabilizer, poly vinyl chloride (PVC) and additives, and then functionalized on the ZnO nanorods that have shown the Nernstian response with the slope of 31 mV/decade. However, the Cu2+ ion sensor was fabricated only by immobilizing the selective copper ion ionophore membrane without the use of PVC, plasticizers, additives and stabilizers and the sensor electrode showed a linear potentiometric response with a slope of 56.4 mV/decade within a large dynamic concentration range (from 1.0 x 10(-6) to 1.0 x 10(-1) M) of copper (II) nitrate solutions. The sensor showed excellent repeatability and reproducibility with response time of less than 10 s. The negligible response to potentially interfering metal ions such as calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe3+), zinc (Zn2+), and sodium (Na+) allows this sensor to be used in biological studies. It may also be used as an indicator electrode in the potentiometric titration.

Place, publisher, year, edition, pages
American Scientific Publishers, 2014
Keywords
ZnO Nanorods; Ionophore; Cu+2 Ion; Potentiometric Sensor; Indicator Electrode
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-107436 (URN)10.1166/jnn.2014.9377 (DOI)000335873900032 ()
Available from: 2014-06-12 Created: 2014-06-12 Last updated: 2017-12-05Bibliographically approved
Khun, K., Ibupoto, Z. H., Liu, X., Mansor, N. A., Turner, A., Beni, V. & Willander, M. (2014). An Electrochemical Dopamine Sensor Based on the ZnO/CuO Nanohybrid Structures. Journal of Nanoscience and Nanotechnology, 14(9), 6646-6652
Open this publication in new window or tab >>An Electrochemical Dopamine Sensor Based on the ZnO/CuO Nanohybrid Structures
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2014 (English)In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6646-6652Article in journal (Refereed) Published
Abstract [en]

The selective detection of dopamine (DA) is of great importance in the modern medicine because dopamine is one of the main regulators in human behaviour. In this study, ZnO/CuO nanohybrid structures, grown on the gold coated glass substrate, have been investigated as a novel electrode material for the electrochemical detection of dopamine. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were used for the material characterization and the obtained results are in good agreement. The selective determination of dopamine was demonstrated by cyclic voltammetry (CV) and amperometric experiments. The amperometric response was linear for dopamine concentrations between 1.0 x 10(-3) and 8.0 mM with a sensitivity of 90.9 mu A mM(-1) cm(-2). The proposed dopamine biosensor is very stable, selective over common interferents as glucose, uric acid and ascorbic acid, and also good reproducibility was observed for seven electrodes. Moreover, the dopamine sensor exhibited a fast response time of less than 10 s. The wide range and acceptable sensitivity of the presented dopamine sensor provide the possible application in analysing the dopamine from the real samples.

Place, publisher, year, edition, pages
American Scientific Publishers, 2014
Keywords
Dopamine; ZnO/CuO Nanohybrid Structures; Cyclic Voltammetry; Amperometry
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-107432 (URN)10.1166/jnn.2014.9367 (DOI)000335873900020 ()
Available from: 2014-06-12 Created: 2014-06-12 Last updated: 2017-12-05Bibliographically approved
Ibupoto, Z. H., Khun, K. & Willander, M. (2014). Development of a pH Sensor Using Nanoporous Nanostructures of NiO. Journal of Nanoscience and Nanotechnology, 14(9), 6699-6703
Open this publication in new window or tab >>Development of a pH Sensor Using Nanoporous Nanostructures of NiO
2014 (English)In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6699-6703Article in journal (Refereed) Published
Abstract [en]

Glass is the conventional material used in pH electrodes to monitor pH in various applications. However, the glass-based pH electrode has some limitations for particular applications. The glass sensor is limited in the use of in vivo biomedical, clinical or food applications because of the brittleness of glass, its large size, the difficulty in measuring small volumes and the absence of deformation (inflexibility). Nanostructure-based pH sensors are very sensitive, reliable, fast and applicable towards in vivo measurements. In this study, nanoporous NiO nanostructures are synthesized on a gold-coated glass substrate by a hydrothermal route using poly(vinyl alcohol) (PVA) as a stabilizer. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used for the morphological and crystalline studies. The grown NiO nanostructures are uniform and dense, and they possess good crystallinity. A pH sensor based on these NiO nanostructures was developed by testing the different pH values from 2-12 of phosphate buffered saline solution. The proposed pH sensor showed robust sensitivity of -43.74 +/- 0.80 mV/pH and a quick response time of less than 10 s. Moreover, the repeatability, reproducibility and stability of the presented pH sensor were also studied.

Place, publisher, year, edition, pages
American Scientific Publishers, 2014
Keywords
pH Sensor; Nickel Oxide; Nanoporous; Buffer Solution
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-107433 (URN)10.1166/jnn.2014.9373 (DOI)000335873900028 ()
Available from: 2014-06-12 Created: 2014-06-12 Last updated: 2017-12-05Bibliographically approved
Ibupoto, Z. H., Khun, K. & Willander, M. (2014). Hydrothermal Growth of CuO Nanoleaf Structures, and Their Mercuric Ion Detection Application. Journal of Nanoscience and Nanotechnology, 14(9), 6711-6717
Open this publication in new window or tab >>Hydrothermal Growth of CuO Nanoleaf Structures, and Their Mercuric Ion Detection Application
2014 (English)In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6711-6717Article in journal (Refereed) Published
Abstract [en]

Mercury is the hazardous heavy metal ion for the environment and the humanbeing therefore its determination is very important and herein we describe the development of mercury ion sensor on the CuO nanoleaf like nanostructures using cetyltrimethylammonium bromide (CTAB) surfactant as template for the growth by hydrothermal growth method. Scanning electron microscopy and X-ray diffraction study has shown high density and good crystal quality of the fabricated CuO nanostructures respectively. The presented mercury ion sensor has detected the wide range of 1.0 x 10(-7) to 1.0 x 10(-1) M mercury ion concentrations with an acceptable Nernstian behaviour and a sensitivity of 30.1 +/- 0.6 mV/decade. The proposed mercury ion sensor exhibited low detection limit of 1.0 x 10(-8) M and also a fast response time of less than 5 s. In addition, the presented mercury ion sensor has shown an excellent repeatability, reproducibility, stability and selectivity. Moreover, the mercury ion selective electrode based on CuO nanoleaves was tested as an indicator electrode in the potentiometric titration.

Place, publisher, year, edition, pages
American Scientific Publishers, 2014
Keywords
CuO Nanoleaf; Mercury Ion Sensor; Ion Selective Electrode; Potentiometric Technique; Output Response
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-107435 (URN)10.1166/jnn.2014.9342 (DOI)000335873900030 ()
Available from: 2014-06-12 Created: 2014-06-12 Last updated: 2017-12-05Bibliographically approved
Willander, M., Khun, K. & Ibupoto, Z. H. (2014). Metal Oxide Nanosensors Using Polymeric Membranes, Enzymes and Antibody Receptors as Ion and Molecular Recognition Elements. Sensors, 14(5), 8605-8632
Open this publication in new window or tab >>Metal Oxide Nanosensors Using Polymeric Membranes, Enzymes and Antibody Receptors as Ion and Molecular Recognition Elements
2014 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 14, no 5, p. 8605-8632Article, review/survey (Refereed) Published
Abstract [en]

The concept of recognition and biofunctionality has attracted increasing interest in the fields of chemistry and material sciences. Advances in the field of nanotechnology for the synthesis of desired metal oxide nanostructures have provided a solid platform for the integration of nanoelectronic devices. These nanoelectronics-based devices have the ability to recognize molecular species of living organisms, and they have created the possibility for advanced chemical sensing functionalities with low limits of detection in the nanomolar range. In this review, various metal oxides, such as ZnO-, CuO-, and NiO-based nanosensors, are described using different methods (receptors) of functionalization for molecular and ion recognition. These functionalized metal oxide surfaces with a specific receptor involve either a complex formation between the receptor and the analyte or an electrostatic interaction during the chemical sensing of analytes. Metal oxide nanostructures are considered revolutionary nanomaterials that have a specific surface for the immobilization of biomolecules with much needed orientation, good conformation and enhanced biological activity which further improve the sensing properties of nanosensors. Metal oxide nanostructures are associated with certain unique optical, electrical and molecular characteristics in addition to unique functionalities and surface charge features which shows attractive platforms for interfacing biorecognition elements with effective transducing properties for signal amplification. There is a great opportunity in the near future for metal oxide nanostructure-based miniaturization and the development of engineering sensor devices.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI, 2014
Keywords
ZnO nanostructures; CuO nanostructures; NiO nanostructures; potentiometric nanosensors; biosensors; chemical sensors
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-108939 (URN)10.3390/s140508605 (DOI)000337112200051 ()
Available from: 2014-07-15 Created: 2014-07-13 Last updated: 2017-12-05Bibliographically approved
Khun, K. (2014). Synthesising Metal Oxide Materials and Their Composite Nanostructures for Sensing and Optoelectronic Device Applications. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Synthesising Metal Oxide Materials and Their Composite Nanostructures for Sensing and Optoelectronic Device Applications
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Research on nanomaterials has been revolutionized in the last few years because of the attractive properties they have in comparison to the bulk phase of similar materials. These properties are physical, chemical, catalytic and optical. Among these nanomaterials, the metal oxide nanostructures have become of particular interest to scientists for the development of different optical, biochemical and biomedical nanodevices. In the present research work using the advantageous features of nanotechnology, high performance nanodevices for optoelectronics with a wide band gap compound nanostructure and highly sensitive sensor devices have been demonstrated. The nanotechnology is used to fabricate sensitive and precise nanodevices based on nanomaterials for the application of sensing.

Among metal oxide nanostructures, ZnO, CuO and NiO are attractive materials because of their unique properties; their high surface area to volume ratio, their energy band gap of 3.37 eV, 1.2 eV and 3.7 eV, respectively, biocompatibility, high electron mobility, fast electron transfer rate and they are environmental-friendly in many applications. When used in sensor devices, nanomaterials have indicated high selectivity for possible use to detect the various analytes even in small volumes. Metal oxide nanostructures have shown to be good for optoelectronic nanodevices because of their electrical characteristics, high optical absorption and low-processing temperature.

In this thesis, the synthesis of different morphologies of metal oxide semiconductor nanostructures and their composite using the hydrothermal method are demonstrated for various applications. This thesis is divided into three parts:

In the first part of this research work, the fabrication of well-aligned ZnO nanorods using different concentrations of composite seed layer of inorganic and organic materials when using the hydrothermal growth method is presented. The effect of the composite seed layer on the alignment, density and optical properties of the grown ZnO nanorods is investigated (paper I). Utilizing the advantage of ZnO nanostructure, a comparative study of ZnO nanorods and thin films for chemical and biosensing application was carried out. The ZnO nanorods and thin films were functionalized with strontium ionophore membrane, immobilized the galactose oxidase and lactate oxidase for determining the strontium ions, D-galactose and L-lactic acid, respectively (paper II).

In the second part, the effects of different urea concentrations on the morphology of CuO nanostructures is studied as described in paper III. Moreover, CuO nanoflowers were functionalized with cadmium ion ionophore for the detection of Cd ions, while CuO nanosheets were grown by the low temperature growth method and were used for the development of a nonenzymatic glucose sensor, respectively (Paper IV).

In the last part of this thesis, composite nanostructures of CuO/ZnO and NiO/ZnO were applied to develop dopamine sensor and fast sensitive UV photodetector, respectively. A nanohybrid of CuO/ZnO nanostructure was used as a non-enzymatic electrode to detect dopamine by cyclic voltammetry (CV) and amperometric techniques (Paper V). In paper VI, we have demonstrated a strong UV absorption from ZnO nano-sheets achieved by the supramoleculesassisted growth solution using the hydrothermal method. The synthesized nanomaterial was used in the fabrication of UV photodetector based on p-NiO/ n-ZnO heterostructures.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. p. 56
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1628
Keywords
Hydrothermal method; metal oxide nanostructure; composite seed solution; wellaligned ZnO nanorods; composite structures; glucose and dopamine non-enzymatic sensors; heavy metals; supramolecular; UV photodetector sensor
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-112865 (URN)10.3384/diss.diva-112865 (DOI)978-91-7519-207-9 (ISBN)
Public defence
2015-01-19, K3, Kåkenhus, Campus Norrköping, Linköpings universitet, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2014-12-18 Created: 2014-12-18 Last updated: 2015-01-14Bibliographically approved
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