| 1. |
- Thorgeirsson, Thorgeir E, et al.
(author)
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A variant associated with nicotine dependence, lung cancer and peripheral arterial disease
- 2008
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 452:7187, s. 9-638
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Journal article (peer-reviewed)abstract
- Smoking is a leading cause of preventable death, causing about 5 million premature deaths worldwide each year(1,2). Evidence for genetic influence on smoking behaviour and nicotine dependence (ND)(3-8) has prompted a search for susceptibility genes. Furthermore, assessing the impact of sequence variants on smoking-related diseases is important to public health(9,10). Smoking is the major risk factor for lung cancer (LC)(11-14) and is one of the main risk factors for peripheral arterial disease (PAD)(15-17). Here we identify a common variant in the nicotinic acetylcholine receptor gene cluster on chromosome 15q24 with an effect on smoking quantity, ND and the risk of two smoking- related diseases in populations of European descent. The variant has an effect on the number of cigarettes smoked per day in our sample of smokers. The same variant was associated with ND in a previous genomewide association study that used low- quantity smokers as controls(18,19), and with a similar approach we observe a highly significant association with ND. A comparison of cases of LC and PAD with population controls each showed that the variant confers risk of LC and PAD. The findings provide a case study of a gene - environment interaction(20), highlighting the role of nicotine addiction in the pathology of other serious diseases.
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| 2. |
- Agustsson, J. S., et al.
(author)
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Electrical resistivity and morphology of ultra thin Pt films grown by dc magnetron sputtering on SiO(2)
- 2008
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In: Journal of Physics Conference Series. - : IOP Science. - 1742-6596.
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Conference paper (peer-reviewed)abstract
- Ultra thin platinum films were grown by dc magnetron sputtering on thermally oxidized Si (100) substrates. The electrical resistance of the films was monitored in-situ during growth. The coalescence thickness was determined for various growth temperatures and found to increase from 1.3 nm for films grown at room temperature to 1.8 nm for films grown at 250 degrees C, while a continuous film was formed at a thickness of 3.9 nm at room temperature and 3.5 nm at 250 degrees C. The electrical resistivity increases with increased growth temperature, as well as the morphological grain size, and the surface roughness, measured with a scanning tunneling microscope (STM).
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| 3. |
- Agustsson, J. S., et al.
(author)
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Growth, coalescence, and electrical resistivity of thin Pt films grown by dc magnetron sputtering on SiO2
- 2008
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In: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 254:22, s. 7356-7360
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Journal article (peer-reviewed)abstract
- Ultra thin platinum films were grown by dc magnetron sputtering on thermally oxidized Si (100) substrates. The electrical resistance of the films was monitored in situ during growth. The coalescence thickness was determined for various growth temperatures and found to increase from 1.1 nm for films grown at room temperature to 3.3 nm for films grown at 400 degrees C. A continuous film was formed at a thickness of 2.9 nm at room temperature and 7.5 nm at 400 degrees C. The room temperature electrical resistivity decreases with increased growth temperature, while the in-plain grain size and the surface roughness, measured with a scanning tunneling microscope (STM), increase. Furthermore, the temperature dependence of the film electrical resistance was explored at various stages during growth.
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| 4. |
- Gudmundsson, Jon Tomas, 1965-, et al.
(author)
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Oxygen discharges diluted with argon : dissociation processes
- 2007
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In: Plasma sources science & technology. - : Institute of Physics Publishing (IOPP). - 0963-0252 .- 1361-6595. ; 16:2, s. 399-412
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Journal article (peer-reviewed)abstract
- We use a global (volume averaged) model to study the dissociationprocesses and the presence of negative ions and metastable species in a lowpressure high density O2/Ar discharge in the pressure range 1–100 mTorr.The electron density and the fractional dissociation of the oxygen moleculeincreases with increased argon content in the discharge. We relate thisincrease in fractional dissociation to an increase in the reaction rate forelectron impact dissociation of the oxygen molecule which is due to theincreased electron temperature with increased argon content in thedischarge. The electron temperature increases due to higher ionizationpotential of argon than for molecular and atomic oxygen. We find thecontribution of dissociation by quenching of the argon metastable Armbymolecular oxygen (Penning dissociation) to the creation of atomic oxygen tobe negligible. The negative oxygen ion O−is found to be the dominantnegative ion in the discharge. Dissociative attachment of the oxygenmolecule in the ground state O2(X3−g)and in particular the metastableoxygen molecule O2(a1g)are the dominating channels for creation of thenegative oxygen ion O−.(Some figures in this article are in colour only in the electronic version)
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| 5. |
- Helmersson, Ulf, et al.
(author)
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Ionized physical vapor deposition (IPVD): A review of technology and applications
- 2006
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 513:1-2, s. 1-24
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Journal article (peer-reviewed)abstract
- In plasma-based deposition processing, the importance of low-energy ion bombardment during thin film growth can hardly be exaggerated. Ion bombardment is an important physical tool available to materials scientists in the design of new materials and new structures. Glow discharges and in particular the magnetron sputtering discharge have the advantage that the ions of the discharge are abundantly available to the deposition process. However, the ion chemistry is usually dominated by the ions of the inert sputtering gas while ions of the sputtered material are rare. Over the past few years, various ionized sputtering techniques have appeared that can achieve a high degree of ionization of the sputtered atoms, often up to 50 % but in some cases as much as approximately 90%. This opens a complete new perspective in the engineering and design of new thin film materials. The development and application of magnetron sputtering systems for ionized physical vapor deposition (IPVD) is reviewed. The application of a secondary discharge, inductively coupled plasma magnetron sputtering (ICP-MS) and microwave amplified magnetron sputtering, is discussed as well as the high power impulse magnetron sputtering (HIPIMS), the self-sustained sputtering (SSS) magnetron, and the hollow cathode magnetron (HCM) sputtering discharges. Furthermore, filtered arc-deposition is discussed due to its importance as an IPVD technique. Examples of the importance of the IPVD-techniques for growth of thin films with improved adhesion, improved microstructures, improved coverage of complex shaped substrates, and increased reactivity with higher deposition rate in reactive processes are reviewed.
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| 6. |
- Lundin, Daniel, 1980-
(author)
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Plasma properties in high power impulse magnetron sputtering
- 2008
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Licentiate thesis (other academic/artistic)abstract
- The work presented in this thesis involves experimental and theoretical studies related to plasma properties in high power impulse magnetron sputtering (HiPIMS), and more specifically plasma transport. HiPIMS is an ionized PVD method based on conventional direct current magnetron sputtering (dcMS). In dcMS very little of the sputtered material is ionized since the plasma power density is not high enough. This is not the case for HiPIMS, where a substantial part is ionized, and thus presents many new opportunities for thin film growth. Understanding the dynamics of the charged species in the HiPIMS discharge is therefore of essential value when producing high-quality thin film coatings.In the first part of the work a new type of anomalous electron transport was found. Investigations of the transport resulted in the discovery that this phenomenon could quantitatively be described as being related and mediated by highly nonlinear waves, likely due to the modified two-stream instability (MTSI), resulting in electric field oscillations in the MHz-range (the so-called lower hybrid frequency). Measurements in the plasma confirmed these oscillations as well as trends predicted by the theory of these types of waves. The degree of anomalous transport in the plasma could also be determined by measuring the current density ratio between the azimuthal current density (of which the Hall current density is one contribution) and the discharge current density, Jφ / JD. The results provided important insights into understanding the mechanism behind the anomalous transport.It was furthermore found that the current ratio Jφ / JD is inversely proportional to the transverse resistivity, eta_perpendicular , which governs how well momentum is transferred from the electrons to the ions in the plasma. By looking at the forces involved in the charged particle transport it was expected that the azimuthally rotating electrons would exert a volume force on the ions tangentially outwards from the circular race track region. The effect of having an anomalous transport would therefore be a large fraction of highly energetic ions being transported sideways and lost to the walls. In a series of experiments, deposition rates as well as incoming ion energy distributions were measured directly at the side of the magnetron. It was found that a substantial fraction of sputtered material is transported radially away from the cathode and lost to the walls in HiPIMS as well as dcMS, but more so for HiPIMS giving one possible explanation to why the deposition rate for substrates placed in front of the target is lower for HiPIMS compared to dcMS. Furthermore, the recorded, incoming ion energy distributions confirmed theoretical estimations on this type of transport regarding energy and direction.
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| 7. |
- Magnus, Fridrik, et al.
(author)
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Digital Smoothing of the Langmuir Probe I-V Characteristic
- 2008
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In: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 79:7
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Journal article (peer-reviewed)abstract
- Electrostatic probes or Langmuir probes are the most common diagnostic tools in plasma discharges. The second derivative of the Langmuir probe I-V characteristic is proportional to the electron energy distribution function. Determining the second derivative accurately requires some method of noise suppression. We compare the Savitzky-Golay filter, the Gaussian filter, and polynomial fitting to the Blackman filter for digitally smoothing simulated and measured I-V characteristics. We find that the Blackman filter achieves the most smoothing with minimal distortion for noisy data.
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