Interface control of atomic layer deposited oxide coatings by filtered cathodic arc deposited sublayers for improved corrosion protection

Sublayers grown with filtered cathodic arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al₂O₃–Ta₂O₅ nanolaminate, Al_xTa_yO_z mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing.     

Low level gas multicounter for 14C dating of small samples

A compact gas multicounter has been constructed and is undergoing tests. Up to 14 methane samples can be counted simultaneously in an array of 10 ml (at NTP) copper counters at a pressure of 1–8 bar. The gas filling, application of high voltage and decay energy monitoring are microprocessor controlled. Multichannel analyses (256 ch. sample and cosmic detector energy data), sample identity, counting time and critical validity parameters are stored on disc. Numerical discrimination and manipulations of counting parameters can be performed without destroying the original data set. Statistical quality control is based on chi-square and Poisson distribution of countrates around their mean in user defined energy regions as well as “ time of arrival” (TA) of pulses mode. TA analysis offers the user an early means of recognition of some types of system malfunction that otherwise might remain undetected for long periods of time. Pulse shape analysis is used to discriminate sample beta from environmental radiation pulses resulting in a low background with compact and relatively inexpensive shielding.     

Copolymerization of propene with phenylnorbornene using ansa‐bridged metallocene catalysts

Propene was copolymerized with phenylnorbornene using methylaluminumoxane (MAO)‐activated metallocene dichlorides exhibiting different symmetry: C₂‐Symmetric rac‐ethylenebis(1‐ indenyl)zirconium dichloride ( 1 ), rac‐ dimethylsilylbis(1‐indenyl)zirconium dichloride ( 2 ), rac‐ethylenebis(1‐indenyl)hafnium dichloride ( 6 ), C_s‐symmetric isopropylidene(cyclopentadienyl‐9‐fluorenyl)zirconium dichloride ( 3 ), meso‐ethylenebis(1‐indenyl)zirconium dichloride ( 4 ), and C₁‐symmetric ethylene(1‐ fluorenyl‐1‐phenyl‐2‐indenyl)zirconium dichloride ( 5 ) were chosen to evaluate the influence of the symmetry in copolymerization reactions. Experiments were done as batch polymerizations to produce homogeneous copolymers. By this setup, blend formation was avoided. The copolymers were characterized by NMR, GPC, and DSC. Catalysts 1 and 2 were the most active to copolymerize random, amorphous, copolymers with good activity. C_s‐symmetric, 3 , showed decreased activity compared with 1 and 2 and produced a bimodal copolymer. Catalyst 4 showed even lower activity than that of 3 . The activity of the hafnium complex 6 , which produced a semicrystalline polymer with a high molecular weight (116,000 g/mol) was 320 kg/mol. Catalyst 1 produced the highest comonomer content (42%) in the copolymers measured by NMR. The least active catalyst was 5 (phenyl croup in the bridge), producing only 290 kg copolymer per mole of catalyst. All polymers had elevated glass transition temperatures compared to polypropylene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2743–2752, 2002     

The ALSM algorithm — an improved subspace method of classification

The subspace methods of classification are decision-theoretic pattern recognition methods in which each class is represented in terms of a linear subspace of the Euclidean pattern or feature space. In most reported subspace methods, a priori criteria have been applied to improve either the class representation or the discriminatory power of the subspaces. Recently, construction of the class subspaces by learning has been suggested by Kohonen, resulting in an improved classification accuracy. A variant of the original learning rule is analyzed and results are given on its application to the classification of phonemes in automatic speech recognition.     

Determining the irradiance signal from an asymmetric source with directional detectors: application to calibrations of radiometers with diffusers

The energy transfer integral between radiating rectangular and detecting circular parallel plates having nonideal angular characteristics is solved for modeling the distance dependence of the irradiance signal. The equation derived for the irradiance signal, which is called the modified inverse-square law, depends on the position, shape, size, and angular characteristics of the light source and the detector. We apply the new model equation to the calibration of a spectroradiometer to determine accurately the distance offsets, which fix the positions of the effective receiving apertures of diffusers used in the entrance optics of spectroradiometers. Earlier measurement results, e.g., for solar UV irradiance, may include uncorrected effects and can be corrected reliably as diffuser offsets and other correction factors are determined with the modified inverse-square law. Simplifications of the modified inverse-square law for analyzing the distance offsets and the correction factors are studied. Simplified equations for the diffuser offset analysis may be used without losing the accuracy when the cosine response of the diffuser is reasonably good. However, for diffusers whose angular responsivities deviate much from the cosinusoidal angular responsivity, large approximation errors in the diffuser offset values may appear if the angular effects are not properly taken into account.     

Antibacterial effect of bioactive glasses on clinically important anaerobic bacteria in vitro

Bioactive glasses (BAGs) of different compositions have been studied for decades for clinical use and they have found many dental and orthopaedic applications. Particulate BAGs have also been shown to have antibacterial properties. This large-scale study shows that two bioactive glass powders (S53P4 and 13–93) and a sol–gel derived material (CaPSiO II) have an antibacterial effect on 17 clinically important anaerobic bacterial species. All the materials tested demonstrated growth inhibition, although the concentration and time needed for the effect varied depending on the BAG. Glass S53P4 had a strong growth-inhibitory effect on all pathogens tested. Glass 13–93 and sol–gel derived material CaPSiO II showed moderate antibacterial properties.     

Psychosocial dimensions of solving an indoor air problem

This investigation focuses on the psychological and social dimensions of managing and solving indoor air problems. The data were collected in nine workplaces by interviews (n = 85) and questionnaires (n = 375). Indoor air problems in office environments have traditionally utilized industrial hygiene or technical expertise. However, indoor air problems at workplaces are often more complex issues to solve. Technical questions are inter-related with the dynamics of the work community, and the cooperation and interaction skills of the parties involved in the solving process are also put to the test. In the present study, the interviewees were very critical of the process of solving the indoor air problem. The responsibility for coordinating the problem-managing process was generally considered vague, as were the roles and functions of the various parties. Communication problems occurred and rumors about the indoor air problem circulated widely. Conflicts were common, complicating the process in several ways. The research focused on examining different ways of managing and resolving an indoor air problem. In addition, reference material on the causal factors of the indoor air problem was also acquired. The study supported the hypothesis that psychosocial factors play a significant role in indoor air problems.     

Structure-from-motion without correspondence from tomographic projections by Bayesian inversion theory

In conventional tomography, the interior of an object is reconstructed from tomographic projections such as X-ray or transmission electron microscope images. All the current reconstruction methods assume that projection geometry of the imaging device is either known or solved in advance by using e.g., fiducial or nonfiducial feature points in the images. In this paper, we propose a novel approach where the imaging geometry is solved simultaneously with the volume reconstruction problem while no correspondence information is needed. Our approach is a direct application of Bayesian inversion theory and produces the maximum likelihood or maximum a posteriori estimates for the motion parameters under the selected noise and prior distributions. In this paper, the method is implemented for a two-dimensional model problem with one-dimensional affine projection data. The performance of the method is tested with simulated and measured X-ray projection data.