Calcium phosphate nucleation on surface-modified PTFE membranes

Highly porous PTFE membranes are currently being used in facial reconstructive surgery. The present study aims at improving this biomaterial through creating a more bioactive surface by introducing ionic groups onto the surface. The unmodified PTFE membrane does not induce inorganic growth after immersion in simulated body fluid (SBF) for up to 4 weeks. Copolymeric grafting with acrylic acid (AAc) by means of gamma irradiation and subsequent in vitro testing in SBF reveals that this copolymer initially acts as an ion-exchange material and subsequently induces growth of a calcium phosphate phase (Ca/P=2.7) when large amounts (15%) of pAAc are introduced onto the membrane surface. This copolymer is not expected to function well from a biomaterials perspective since SEM showed the pores on the surface to be partly blocked. In contrast, the surface of monoacryloxyethyl phosphate (MAEP)-modified samples is altered at a molecular level only. Yet the modified materials are able to induce calcium phosphate nucleation when the external surface coverage is 44% or above. The initial inorganic growth on these membranes in SBF has a (Ca+Mg)/P ratio of 1.1 (presumably Brushite or Monetite). The secondary growth, possibly calcium-deficient apatite or tricalcium phosphate, has a (Ca+Mg)/P ratio of 1.5. This result is a promising indicator of a bioactive biomaterial.     

Mislocations in ERS-1 SAR geocoded images

ERS-1 Synthetic Aperture Radar geocoded images (SAR.GEC) are supposed to be accurate to within 150 m. Nevertheless, errors of more than 1000 m (especially in the longitudinal direction) have been discovered. The errors are due to the geometric processing routine, which has shortcomings in mountainous and/or coastal areas: the geoid height in the centre pixel of the image is used as a mean geoid height for the whole 100 × 100 km² image. This means that sea areas and land areas cannot have correct coordinates at the same time.     

A demonstration of level-anchored ratio scaling for prediction of grip strength

Level-anchored ratio scaling, such as the Borg CR10 scale^® and the Borg CR100 scale^®, uses verbal anchors in congruence with numbers to give ratio data together with natural levels of intensity. This presupposes that the anchors possess natural positions in the subjective dynamic range and also “numerical” inter-relations. In an experiment, subjects had to produce a force of handgrip corresponding to their conception of “Strong”, followed by a “Maximal” performance. By using the previously found relationship between “Strong” and “Maximal” of 1:2 together with knowledge of the exponent in the power S-R-function (R = c × Sⁿ) for grip strength, n = 1.8, predictions of individual maximal performances were obtained. The predicted values correlated 0.76 with, and deviated only 3% (ns) from, actual maximal performances of grip strength. This result –as previously also found for aerobic capacity–gives a strong support for the use of verbal anchors, so common in category scaling, also in “ratio scaling” and that the Borg CR-scales fulfill the requirements for ratio scales. For estimation of muscular strength, such as grip strength, this present study points to the value of using submaximal determinations as a compliment to maximal performances (e.g., to obtain measures of functional capacity). The results also support the increasingly common use of the CR-methodology in other ergonomic settings concerning suitable design of tools and equipment.     

Selection of third party software in Off-The-Shelf-based software development—An interview study with industrial practitioners

The success of software development using third party components highly depends on the ability to select a suitable component for the intended application. The evidence shows that there is limited knowledge about current industrial OTS selection practices. As a result, there is often a gap between theory and practice, and the proposed methods for supporting selection are rarely adopted in the industrial practice. This paper's goal is to investigate the actual industrial practice of component selection in order to provide an initial empirical basis that allows the reconciliation of research and industrial endeavors. The study consisted of semi-structured interviews with 23 employees from 20 different software-intensive companies that mostly develop web information system applications. It provides qualitative information that help to further understand these practices, and emphasize some aspects that have been overlooked by researchers. For instance, although the literature claims that component repositories are important for locating reusable components; these are hardly used in industrial practice. Instead, other resources that have not received considerable attention are used with this aim. Practices and potential market niches for software-intensive companies have been also identified. The results are valuable from both the research and the industrial perspectives as they provide a basis for formulating well-substantiated hypotheses and more effective improvement strategies.     

The effects of reduction of the deposited waste on short‐term landfill leachate composition of a landfill: a case study in Norway

Municipal solid waste landfill leachate was sampled over from a landfill receiving varying amounts of municipal solid waste. The investigation aimed to provide information on expected leachate changes in the short term, either after closure of an active landfill, or after a strong decline in the amount of waste deposited at smaller landfills. It was found that during a two year period following a sudden decline in the amount of waste deposited, the levels of various chemical and physical parameters all dropped sharply. The reasons for the decline in discharge levels are thought to be aerobic decomposition taking place in the municipal solid waste just after landfilling, and thus the decline in the impact of this process when there were less fresh waste masses available, and formation of preferential flow paths for the leachate as the municipal solid waste stabilized in the landfill.     

An 8-bit, 200 MSPS Folding and Interpolating ADC

An 8-bit, 200 MSPS folding and interpolating analog-to-digitalconverter, ADC, has been implemented in a 1.2 µmBiCMOS-process. It achieves 7.5 effective bits with a power dissipationof 575mW. The active area is 4mm². The implementationand measured results are presented. A simple analytical modelfor the interpolation-induced nonlinearity in a folding and interpolatingADC using sinusoidal folding is presented. The bowing of thereference ladder due to interaction with the input stages isanalyzed, and analytical models are derived.     

Fe calculations of stress fields from cracks located at the fusion line of weldments

This paper investigates the stress fields for a crack located at the fusion line of a weldment. The strength mis-matching and the size of the HAZ were varied, and the corresponding distribution of the maximum principal stress was examined. The weld metal strength was globally overmatched with respect to the base material, but locally over- and undermatched with respect to the heat affected zone. Three cases of mis-match were compared, and it was found that reducing the strength of the HAZ lowered the maximum principal stresses.     

Control strategies used by experienced marine navigators: observation of verbal conversations during navigation training

This article investigates the relationship between the control situation framework, as presented by Bjørkli et al. (Cogn Technol Work 9:67–80, 2007), and observed operator action and communication in high-speed craft operation in the Norwegian Royal Navy. The reported data include two series of events during sailing in the Norwegian archipelago where uncertainty of ship position, challenges of manoeuvring and navigation strategies are addressed. The results indicate that the navigators perform actions and communicate in accordance with the key features of the control situation framework, and thus adapt to the interrelation between control possibilities and control requirements. The navigators were guided by explicit knowledge of the functional characteristics of psychical and temporal dynamics, which were actualized in manoeuvring. It indicates that the control situation framework can be used to describe the models the operators use.     

The effect of synthesis gas composition on the Fischer–Tropsch synthesis over Co/γ-Al2O3 and Co–Re/γ-Al2O3 catalysts

The Fischer–Tropsch synthesis over Co/γ-Al₂O₃ and Co–Re/γ-Al₂O₃ was investigated in a fixed-bed reactor at 20 bar and 483 K using feed gases with molar H₂/CO ratios of 2.1, 1.5 and 1.0 simulating synthesis gas derived from biomass. With lower H₂/CO ratios in the feed, the CO conversion and the CH₄ selectivity decreased, while the C₅₊ selectivity and olefin/paraffin ratio for C₂–C₄ increased slightly. The water–gas shift activity was low for both catalysts, resulting in high molar usage ratios of H₂/CO (close to 2.0), even at the lower inlet ratios (i.e. 1.5 and 1.0). For both catalysts, the drop in the production rate of hydrocarbons when shifting from an inlet ratio of 2.1 to 1.5 was significant mainly because the H₂/CO usage ratio did not follow the change in the inlet ratio. The hydrocarbon selectivities were rather similar for inlet H₂/CO ratios of 2.1 and 1.5, while significantly deviating from those for an inlet ratio of 1.0. With the studied catalysts, it is possible to utilize the advantages of an inlet ratio of 1.0 (higher selectivity to C₅₊, lower selectivity to CH₄, no water–gas shifting of the bio-syngas needed prior to the FT reactor) if a low syngas conversion is accepted.