| 1. |
- Wang, Jing, 1982-
(författare)
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Fabrication and Characterization of Photonic Crystals, Optical Metamaterials and Plasmonic Devices
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanophotonics is an emerging research field that deals with interaction between light and matter in a sub-micron length scale. Nanophotonic devices have found an increasing number of applications in many areas including optical communication, microscopy, sensing, and solar energy harvesting especially during the past two decades. Among all nanophotonic devices, three main areas, namely photonic crystals, optical metamaterials and plasmonic devices, gain dominant interest in the photonic society owning to their potential impacts. This thesis studies the fabrication and characterization of three types of novel devices within the above-mentioned areas. They are respectively photonic-crystal (PhC) surface-mode microcavities, optical metamaterial absorbers, and plasmonic couplers. The devices are fabricated with modern lithography-based techniques in a clean room environment. This thesis particularly describes the critical electron-beam lithography step in detail; the relevant obstacles and corresponding solutions are addressed. Device characterizations mainly rely on two techniques: a vertical fiber coupling system and a home-made optical transmissivity/reflectivity setup. The vertical fiber coupling system is used for characterizing on-chip devices intended for photonic integrations, such as PhC surface-mode cavities and plasmonic couplers. The transmissivity/reflectivity setup is used for measuring the absorbance of metamaterial absorbers. This thesis presents mainly three nanophotonic devices, from fabrication to characterization. First, a PhC surface-mode cavity on a SOI structure is demonstrated. Through a side-coupling scheme, a system quality-factor of 6200 and an intrinsic quality-factor of 13400 are achieved. Such a cavity can be used as ultra-compact optical filter, bio-sensor and etc. Second, an ultra-thin, wide-angle metamaterial absorber at optical frequencies is realized. Experimental results show a maximum absorption peak of 88% at the wavelength of ~1.58μm. The ultra-fast photothermal effect possessed by such noble-metal-based nanostructure can potentially be exploited for making better solar cells. Finally, we fabricated an efficient coupler that channels light from a conventional dielectric waveguide to a subwavelength plasmonic waveguides and vice versa. Such couplers can combine low-loss dielectric waveguides and lossy plasmonic components onto one single chip, making best use of the two.
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| 2. |
- Wang, Eric Min-yang
(författare)
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Usability evaluation for human-computer interaction (HCI)
- 1992
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Computer systems are becoming more and more complicated, powerful, and mysterious, but if the systems is not easy to learn nor easy to use, they will be creating problems to the users, particularly to the novices. As the use of computers in the society from day to day is widespread, by more and more ordinary people, the operation of the systems should be simple enough to really help them but not puzzle them. In order to develop a usable (i.e., easy to learn and easy to use) computer system and utilise the system to its full capabilities, considerations of human factors aspects in the designs of both hardware and software of computer systems are of vital importance. This leads to increasingly emphasis in usability of computer systems in recent years by many researchers, computer system developers and manufacturers. Probably, there is far more usability knowledge yet to be explored but the needs of usability evaluation are immediate. This thesis is focused on human factors issues of the computer technology - the evaluation of usability for Human-Computer Interaction (HCI) It starts with an overview on HCI research, the ideas of user-friendliness / usability, and the design strategies. Usability evaluation approaches am compared and fundamental usability factors are discussed, followed by the reports of the author's case studies. Based on the development trend of computer systems and our findings, it is suggested that more efforts should be made to the early considerations of usability in the system development life cycles. To help designers to do selfevaluation of their systems at early development stage, the Do-it-yourself Usability Evaluation (DUE) approach is developed and recommended. Further studies are also suggested. With the on-going and future development of multimedia, broadband network communications, computer supported cooperative work, and system integration, usability design is inevitable and has to be considered in time. This work is expected to be beneficial for computer system developers and manufacturers who would like to produce high user satisfactory products for their users. It is also useful for users who would like to have enjoyable experience with easy-to-learn and easy-to-use computer systems as well as maximize their performance.
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| 3. |
- Wang, Min, 1985-
(författare)
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Biolubricants and Biolubrication
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of this thesis work was to gain understanding of the principles of biolubrication, focusing on synergistic effects between biolubricants. To this end surface force and friction measurements were carried out by means of Atomic Force Microscopy, using hydrophilic and hydrophobic model surfaces in salt solutions of high ionic strength (≈ 150 mM) in presence of different biolubricants. There was also a need to gain information on the adsorbed layers formed by the biolubricants. This was achieved by using a range of methods such as Atomic Force Microscopy PeakForce imaging, Quartz Crystal Microbalance with Dissipation, Dynamic Light Scattering and X-Ray Reflectometry. By combining data from these techniques, detailed information about the adsorbed layers could be obtained.The biolubricants that were chosen for investigation were a phospholipid, hyaluronan, lubricin, and cartilage oligomeric matrix protein (COMP) that all exist in the synovial joint area. First the lubrication ability of these components alone was investigated, and then focus was turned to two pairs that are known or assumed to associate in the synovial area. Of the biolubricants that were investigated, it was only the phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) that was found to be an efficient lubricant on its own. Deposited DPPC bilayers on silica surfaces were found to be able to provide very low friction coefficients (≈ 0.01) up to high pressures, ≈ 50 MPa. A higher load bearing capacity was found for DPPC in the liquid crystalline state compared to in the gel state.The first synergy pair that was explored was DPPC and hyaluronan, that is known to associate on the cartilage surface, and we also noticed association between hyaluronan and DPPC vesicles as well as with adsorbed DPPC bilayers. By combining these two components a lubrication performance similar to that of DPPC alone could be achieved, even though the friction coefficient in presence of hyaluronan was found to be slightly higher. The synergy here is thus not in form of an increased performance, but rather that the presence of hyaluronan allows a large amount of the phospholipid lubricant to accumulate where it is needed, i.e. on the sliding surfaces.The other synergy pair was lubricin and COMP that recently has been shown to be co-localized on the cartilage surface, and thus suggested to associate with each other. Lubricin, as a single component, provided poor lubrication of PMMA surfaces, which we utilized as model hydrophobic surfaces. However, if COMP first was allowed to coat the surface, and then lubricin was added a low friction coefficient (≈ 0.03) was found. In this case the synergy arises from COMP facilitating strong anchoring of lubricin to the surface in conformations that provide good lubrication performance.
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| 4. |
- Wang, Min
(författare)
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Characteristics of BVOC emissions from a Swedish boreal forest : Using chambers to capture biogenic volatile organic compounds (BVOCs) from trees and forest floor
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plant-emitted biogenic volatile organic compounds (BVOCs) are a large group of hydrocarbons released by plant leaves, bark, flowers and fruits into the atmosphere and from plant roots into the soil. BVOCs have important physiological and ecological functions, such as mediating within-plant and plant-plant communication, defense against herbivores attack, protection against heat or other oxidative stress, attracting pollinators etc., and BVOCs are also important for microorganisms’ communication and nutrient cycling in the soil. These emitted reactive BVOCs also have impact on atmospheric chemistry, such as affecting the oxidation rate and atmospheric concentration of other trace gases, and the oxidized BVOCs contribute to particles formation and growth. The most abundant BVOCs are terpenes, such as isoprene (C5H8), monoterpene (MT, C10H16) and sesquiterpene (SQT, C15H24), and woody plants tend to emit various blends of terpenes. Norway spruce and Scots pine are two dominant boreal species, which have been recognized as MT emitters, and Norway spruce is also known as a low isoprene emitter. The contribution of forest floor to the ecosystem BVOC emissions has not been thoroughly studied and evaluated.A dynamic branch chamber system was used in this thesis to quantify the BVOC emission rates and emission spectra (composition of compounds) from 20-m and lower canopy levels of a Norway spruce and from 20-m canopy of a Scots pine from June to September of 2013 and 2014. The observed BVOC emissions from 20-m canopy of Norway spruce peaked in August 2013 and July 2014, and the minimum was found in September in both two years. The total BVOC emission rates of 2013 were significantly higher than those of 2014, and these high emissions in 2013 were likely induced by insect attack. High induced MT emissions from Scots pine were also observed in September 2014. Besides the long-term observation including seasonal variations are needed for accurately estimating or scaling up BVOC emissions, the stress-induced BVOC emissions are necessary to be incorporated into the emission models given the observed high amount of induced emissions. No clear vertical distribution pattern of BVOC emission rates was found within-canopy of the Norway spruce, and the compounds detected on different canopy levels were quite similar. A dynamic soil chamber was used to quantify the BVOC emissions from the forest floor from June to October of 2015. The peak emission was observed in October. Litterfall might be an important source for MT emissions, especially in autumn. Air temperature inside chamber and PAR (photosynthetically active radiation) were the most influential environmental variables affecting MT and SQT emissions. The understorey vegetation coverage and composition and soil moisture also have impact on the BVOC emissions from the forest floor.
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| 5. |
- Wang, Min
(författare)
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Importance of insulin-like growth factor-1 receptor and EWS/FLI-1 fusion protein in growth and survival of two different types of neuroectodermal tumor cells
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Treatment with comparatively low doses of the 3-hydroxy-3-metylglutaryl coenzyme A (HMG-CoA) reductase inhibitor lovastatin caused growth arrest in both melanoma cells and Ewing's sarcoma (ES) cells. In melanoma cells growth inhibition was correlated with a drastic decrease in N-linked glycosylation of the insulin-like growth factor-1 receptor (IGF-1R), which in turn was followed by a decreased expression of IGF-1 binding sites at the cell surface. These data suggest that IGF-1R constitutes a link between HMG-CoA reductase, which catalyzes the conversion of HMG-CoA to mevalonate (MVA), and cell growth. This hypothesis was supported by the finding that addition of dolichyl phosphate, a product of MVA which functions as a carrier of activated oligosaccharides in glycoprotein assembly, stimulated IGF-1R expression and DNA synthesis in lovastatin-arrested cells. Inhibition of N-linked glycosylation, using tunicamycin, led to apoptotic cell death in both melanoma and ES cells. The same effect was obtained by an antibody ([alpha]IR-3) blocking the binding domain of IGF-1R These data therefore suggest that TM-induced cell death was due to a reduced plasma membrane expression of IGF-1R. As distinguished from melanoma cells, apoptosis of ES cells following ([alpha]IR-3-mediated blocking of IGF-1R was not preceded by growth arrest. Since inhibition of N-linked glycosylation caused both growth arrest and apoptosis in ES cells, it can be concluded that TM-induced growth inhibition is not mediated by the down-regulation of IGF-1R. in these cells. TM treatment also reduced the expression of the EWS/FLI-1 fusion protein, a gene product resulting from the ES-specific t(11;22) translocation. Using antisense oligonucleotides it was shown that the fusion protein is required for ES cell growth. The decreased expression of the fusion protein, which is not a glycoprotein, was due to a destabilization of de novo-synthesized proteins. The mechanisms by which N-linked glycosylation regulates the EWS/FLI-1 fusion protein are unknown but could involve the action of plasma membrane-bound glycoproteins. It was, however, confirmed that the IGF-1 pathway is not involved in this regulation.
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