| 1. |
- Alam, Anzar, et al.
(författare)
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Online surface characterization of paper and paperboards in a wide-range of the spatial wavelength spectrum
- 2012
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 258:20, s. 7928-7935
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Tidskriftsartikel (refereegranskat)abstract
- In the paper industry, surface topography is the essence of both paper and paperboard, and accurate topographical measurements are equally essential in order to achieve a uniform smooth surface. The traditional laboratory methods measure only a few samples from the entire tambour and there are other obvious limitations to this approach. Online measurements may be of significant value to improve the surface quality throughout the production. Roughness is one of the topography components and the majority of techniques measure paper by means of a single predictor of average roughness, R a which is inadequate in providing a comprehensive characterization of the surface. Measurements, in a wide range ofwavelengths, can characterize topography components such as roughness, waviness, cockling, etc. Online measurements were taken for various grades of 8 paper reels, containing the wireside and topsides for newspaper, and uncoated and coated sides of paperboards. Their surfacecharacterization, in the spatial wavelength spectrum, from 0.1 to 10 mm was obtained. This article presents the online characterizationresults which have efficiently distinguished the surfaces of same family materials including the edge and the middle position reels of fine coatedpaperboard. Online measurements were taken, at Iggesund Paperboard Pilot Coater in Sweden, by using a recently developed OnlineTopography (OnTop) device which is based on the principle of light triangulation. © 2012 Elsevier B.V. All rights reserved.
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| 2. |
- Bergström, David, et al.
(författare)
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The absorptance of steels to Nd:YLF and Nd:YAG laser light at room temperature
- 2007
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 253:11, s. 5017-5028
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Tidskriftsartikel (refereegranskat)abstract
- The measurement of absorptance is important for the analysis and modelling of laser-material interactions. Unfortunately, most of the absorptance data presently available considers only polished pure metals rather than the commercially available (unpolished, oxidised) alloys, which are actually being processed in manufacturing. This paper presents the results of absorptance measurements carried out at room temperature on as-received engineering grade steels including hot and cold rolled mild steel and stainless steels of various types. The measurements were made using an integrating sphere with an Nd:YLF laser at two wavelengths (1053 and 527 nm, which means that the results are also valid for Nd:YAG radiation at 1064 and 532 nm). The absorptance results obtained differ considerably from existing data for polished, pure metals and should help improve the accuracy of laser-material interaction models. Some clear trends were identified; for all materials studied, the absorptance was considerably higher than the previously published values for the relevant pure metals with polished surfaces. For all 15 samples the absorptance was higher for the green than for the infrared wavelength. No clear trend correlating the absorptance with the roughness was found for mild steel in the roughness range Sa 0.4-5.6 μm. A correlation between absorptance and roughness was noted for stainless steel for Sa values above 1.5 μm.
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| 3. |
- Bocelli, S, et al.
(författare)
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Experimental identification of the optical phonon of CoSi2 in the infrared
- 1995
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 91:1-4, s. 30-33
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Tidskriftsartikel (refereegranskat)abstract
- A weak but clear optical structure was detected at 329 cm−1 by both reflectance and transmittance measurements in the far infrared on a 430 Å film of CoSi2 grown on Si(100). This is the first observation of the IR vibrational mode of the cubic structure of CoSi2 and the result is in very good agreement with theoretical calculations. In order to characterize the sample, the reflectance was extended up to 5.2 × 104 cm−1 and the refractive index was also directly obtained in a more limited spectral range by spectroscopic ellipsometry. The IR structure was then quantitatively analyzed by means of a fit procedure, obtaining the values of ω0 = 327 cm−1 for the phonon energy, of γ = 10.5 cm−1 for the damping parameter and of 0.006 electronic charges for the screened effective ionic charge.
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| 4. |
- Graça, Juliana Santos, et al.
(författare)
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On the importance of controlling film architecture in detecting prostate specific antigen
- 2018
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 434, s. 1175-1182
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Tidskriftsartikel (refereegranskat)abstract
- Immunosensors made with nanostructured films are promising for detecting cancer biomarkers, even at early stages of the disease, but this requires control of film architecture to preserve the biological activity of immobilized antibodies. In this study, we used electrochemical impedance spectroscopy (EIS) to detect Prostate Specific Antigen (PSA) with immunosensors produced with layer-by-layer (LbL) films containing anti-PSA antibodies in two distinct film architectures. The antibodies were either adsorbed from solutions in which they were free, or from solutions where they were incorporated into liposomes of dipalmitoyl phosphatidyl glycerol (DPPG). Incorporation into DPPG liposomes was confirmed with surface plasmon resonance experiments, while the importance of electrostatic interactions on the electrical response was highlighted using the Finite Difference Time-Domain Method (FDTD). The sensitivity of both architectures was sufficient to detect the threshold value to diagnose prostate cancer (ca. 4 ng mL−1). In contrast to expectation, the sensor with the antibodies incorporated into DPPG liposomes had lower sensitivity, though the range of concentrations amenable to detection increased, according to the fitting of the EIS data using the Langmuir-Freundlich adsorption model. The performance of the two film architectures was compared qualitatively by plotting the data with a multidimensional projection technique, which constitutes a generic approach for optimizing immunosensors and other types of sensors.
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| 5. |
- Hjelm, Mats, et al.
(författare)
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Full Band Monte Carlo Study of Bulk and Surface Transport Properties in 4H and 6H-SiC
- 2001
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 184:1-4, s. 194-198
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Tidskriftsartikel (refereegranskat)abstract
- The bulk and surface electron transport properties of the 4H and 6H polytypes of silicon carbide (SiC) are studied using a full band Monte Carlo (MC) program. The model for the electrons is based on data from a full potential band structure calculation using the density functional theory (DFT) in the local density approximation (LDA). Both SiC polytypes have anisotropic transport properties, but the degree and characteristics of the anisotropy is different. In this study, we show how the anisotropy affects the bulk mobility for intermediate angles between the crystal axis and the plane perpendicular to it. Simulations of surface transport properties have also been performed for semiconductor-interface angles up to 15 degrees from the plane perpendicular to the c-axis. We present results for surface mobility and velocity as a function of the electric field component parallel to the interface plane. In the surface mobility simulations, a semi-empirical model for the semiconductor-insulator interface has been used, where it is assumed that the electrons are reflected in two perpendicular planes.
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| 6. |
- Högberg, Björn, et al.
(författare)
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Study of DNA-Coated Nanoparticles as Possible Programmable Self-Assembly Building-Blocks
- 2006
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 252:15, s. 5538-5541
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles coated with single stranded DNA have been shown to efficiently hybridize to targets of complementary DNA. This property might be used to implement programmable (or algorithmic) self-assembly to build nanoparticle structures. However, we argue that a DNA coated nanoparticle by itself cannot be used as a programmable self-assembly building block since it does not have directed bonds. A general scheme for assembling and purifying nanoparticle eight-mers with eight geometrically well-directed bonds is presented together with some preliminary experimental work.
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| 7. |
- Intarasiri, S., et al.
(författare)
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Crystalline quality of 3C-SiC formed by high-fluence C+-implanted Si
- 2007
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 253:11, s. 4836-4842
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Tidskriftsartikel (refereegranskat)abstract
- Carbon ions at 40 keV were implanted into (1 0 0) high-purity p-type silicon wafers at 400 degrees C to a fluence of 6.5 x 10(17) ions/cm(2). Subsequent thermal annealing of the implanted samples was performed in a diffusion furnace at atmospheric pressure with inert nitrogen ambient at 1100 degrees C. Time-of-flight energy elastic recoil detection analysis (ToF-E ERDA) was used to investigate depth distributions of the implanted ions. Infrared transmittance (IR) and Raman scattering measurements were used to characterize the formation of SiC in the implanted Si substrate. X-ray diffraction analysis (XRD) was used to characterize the crystalline quality in the surface layer of the sample. The formation of 3C-SiC and its crystalline structure obtained from the above mentioned techniques was finally confirmed by transmission electron microscopy (TEM). The results show that 3C-SiC is directly formed during implantation, and that the subsequent high-temperature annealing enhances the quality of the polycrystalline SiC.
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| 8. |
- Łukowiec, D., et al.
(författare)
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Formation and role in gas sensing properties of spherical and hollow silver nanoparticles deposited on the surface of electrochemically exfoliated graphite
- 2022
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 580
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Tidskriftsartikel (refereegranskat)abstract
- Synthetic methods to produce electrochemically exfoliated graphite (EEG) and composites containing silver nanoparticles (AgNPs) deposited on the EEG surface are discussed. An aqueous solution KIO3 was used as the electrolyte for the first time; therefore, oxidation and exfoliation mechanisms are described and discussed in detail. The graphite-based nanostructures were characterized by high stability in water and ethanol dispersions. Two composites with spherical or hollow-shaped ultra-fine AgNPs were synthesized and their structure and physicochemical properties are described. Use of CaCl2 with NaBH4 resulted in the formation of hollow nanoparticles on the EEG surface, whereas simple photoreduction synthesized ultra-fine nanoparticles. The role of silver nanoparticles attached to EEG on the gas sensing properties (for NO2) at different temperatures was determined. Gas sensing experiments confirmed that relatively low levels of AgNPs (1.36% and 6.16% for hollow and spherical NPs, respectively) improved the NO2 sensing properties of EEG. Moreover, at higher temperatures (150 °C) and relatively high NO2 concentrations (>50 ppm), the conductivities of both composites switched from p-type to n-type. The composite with a lower nanoparticle loading (1.56 at%) but larger size showed a significantly better dynamic parameters (response and recovery time).
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| 9. |
- Martinez, A, et al.
(författare)
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A Monte Carlo Study of low field transport in Al doped 4H-SiC
- 2001
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 184:1-4, s. 173-177
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Tidskriftsartikel (refereegranskat)abstract
- The ohmic transport of holes in p-type aluminum-doped 4H-SiC samples is investigated using a Monte Carlo (MC) tool based on a full-potential band structure. The temperature and doping dependence of the hole mobility and its anisotropy are calculated and discussed from a physical point of view, where we stress the importance of considering two-band conduction. Acoustic and optical phonon scattering, as well as ionized and neutral impurity scattering, have been considered. The MC program considers incomplete ionization of impurity atoms, and we assume an impurity level with the ionization energy 0.2 eV, corresponding to Al-doped samples. © 2001 Published by Elsevier Science B.V
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| 10. |
- Nilsson, Hans-Erik, et al.
(författare)
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Numerical study of Bloch electron dynamics in wide band-gap semiconductors
- 2001
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 184:1-4, s. 199-203
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we are using numerical calculations to demonstrate the importance of band to band tunneling in wide band-gap semiconductors. We have considered 4H-SiC, 3C-SiC and wurtzite GaN as prototype semiconductors in the demonstration. Wide band-gap semiconductors allow device operation under very high-applied electric fields, where significant band to band tunneling is expected to occur. Hexagonal wide band-gap semiconductors have a valence band structure with a large number of bands separated by rather small energies. Our calculation shows that this leads to a very significant band to band tunneling even at relatively low electric fields. In cubic wide band-gap semiconductors the tunneling is much less pronounced. However, at the valence band maximum the band separations are small enough to allow significant band to band tunneling. The spin-orbit interaction tends to bend the band near the maximum creating degradation from a parabolic curvature. This bending is found to significantly influence the band to band tunneling process. © 2001 Elsevier Science B.V. All rights reserved.
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