Structure and surface properties of diaminocyclohexane plasma polymer films

Plasma polymers of three isomers of diaminocyclohexane (DACH) were deposited on polyethylene, SiO₂, and mica at 20°C. The deposition rate was measured as a function of plasma density and power; a maximum was observed in the latter function. The deposition rate was highest for the monomer with the highest flow rate. The film refractive index was observed to increase with both power density and the degree of fragmentation in the plasma. Film composition was measured by elementary analysis, and was found to be almost identical for each of the three isomers; a mechanism for the polymerization reaction is proposed. The percentage of primary amino groups decreased with increasing power density and with film thickness. Surface force measurements of the thickness and refractive index agreed well with the corresponding ellipsometry values in dry air, and am adhesive force, independent of power density, was measured. When the film was exposed to water vapor, it swelled considerably and the adhesion was determined by capillary forces. Associated with swelling, at high power, was an extremely regular 2-ply rope pattern of protruding material. © 1993 John Wiley & Sons. Inc.     

Prediction of development of fatigue during a simulated ambulance work task from physical performance tests

The aims of this study were (1) to identify which physical performance tests could best explain the development of fatigue during a simulated ambulance work task, (2) to investigate the effect of height and weight and (3) to investigate in what respects these findings differ between female and male ambulance personnel. Forty-eight male and 17 female ambulance personnel completed a test battery assessing cardio-respiratory capacity, muscular strength and endurance, and co-ordination. The subjects also completed a simulated ambulance work task -- carrying a loaded stretcher. The work task was evaluated by development of fatigue. Univariate and multiple regression analyses were used to investigate to what extent the tests in the test battery were able to explain the variance of developed fatigue. The explained variance was higher for female than for male ambulance personnel (time > 70% of HRpeak: R2 = 0.75 vs 0.10, accumulated lactate: R2 = 0.62 vs 0.42, perceived exertion: R2 = 0.75 vs 0.10). Significant predictors in the models were VO2max, isometric back endurance, one-leg rising, isokinetic knee flexion and shoulder extension strength. Height, but not weight, could further explain the variance. The high physical strain during carrying the loaded stretcher implies the importance of investigating whether improved performance, matching the occupational demands, could decrease the development of fatigue during strenuous tasks.     

Profiling the operational behavior of OS device drivers

As the complexity of modern Operating Systems (OS) increases, testing key OS components such as device drivers (DD) becomes increasingly complex given the multitude of possible DD interactions. Currently, DD testing entails a broad spectrum of techniques, where static (requiring source code) and dynamic (requiring the executable image) and static-dynamic testing combinations are employed. Despite the sustained and improving test efforts in the field of driver development, DDs still represent a significant cause of system outages as the coverage is invariably limited by test resources and release time considerations. The basic factor is the inability to exhaustively assess and then cover the operational states, leading to releases of inadequately tested DDs. Consequently, if representative operational activity profiles of DDs within an OS could be obtained, these could significantly improve the understanding of the actual operational DD state space and help focus the test efforts. Focusing on characterizing DD operational activities while assuming no access to source code, this paper proposes a quantitative technique for profiling the runtime behavior of DDs using a set of occurrence and temporal metrics obtained via I/O traffic characterization. Such profiles are used to improve test adequacy against real-world workloads by enabling similarity quantification across them. The profiles also reveal execution hotspots in terms of DD functionalities activated in the field, thus allowing for dedicated test campaigns. A case study on actual Windows XP and Vista drivers using various performance and stability benchmarks as workloads substantiates our proposed approach.     

Contrast agents in acute myocardial infarction

The experimental design in examination of acute myocardial infarctions should be valid in terms of flow, perfusion and re-flow after intervention. The contrast agents concentration in experimental studies can be measured by microdialysis. We have assessed the usefulness of different extracellular and blood pool contrast agents for visualization of the area at risk in coronary artery occlusions. The double contrast technique, where Dy-DTPA-BMA was combined with Gd-DTPA-BMA yielded a superior infarct visualization. Blood pool agents for example NC100/150 injection is also promising in first path myocardial perfusion imaging.     

Mechanical surface characterization: A promising procedure to screen organic coatings

Two ductile coating ma-terials were subjected to a combined indentation and scratch test procedure de-signed to screen a predetermined pattern of many small sample surfaces in a limited time. The screening of 50 surface spots ordered in a matrix pattern on the surface was carried out in 4.5 hr. The test provides reproducible data in terms of indentation modulus, elastic recovery, scratch penetration depth, and scratch residual depth, and also offers the possibility of detecting critical mechanical transitions such as rupture. The presented procedure produces sufficient data in a limited time scale to fulfill the requirements for a fast method to screen coating compositions. Dept. Polymer Technology, SE-100 44 Stockholm, Sweden. Jaquet-Droz 1, CH-2007 Neuchatel, Switzerland.     

Effects of thiol additives on urethane acrylate UV primers for SMC applications

Sheet molded compound (SMC) is a highly filled, glass fiber reinforced, thermoset material used in trim and body panel automotive parts. When SMC-substrates are coated with conventional thermally cured paints, inherent porosity and entrapped volatiles of the substrate result in popping (“paint pops”) defects. UV-curable primers (UVP) provide an order of magnitude reduction of paint defects in SMC coatings, but typically have poor adhesion. Mercaptan polymers have a long history, dating back to 1928, of use in adhesives and sealant applications. The present study investigates a series of UVPs, showing the effect of resin functionality and thiol functional additive content on the adhesion of the coatings to SMC substrates. The SMC formulation is also considered when evaluating UVP adhesion, regarding variables such as surface chemistry, morphology, and surface area. The present study brings to light how adhesion of acrylate UVP can be enhanced with mercaptan moieties in additive amounts. The effect is most apparent on SMC substrates that have been treated to expose inorganic fillers as opposed to untreated surfaces of polyester. Additionally annealing the films boosts adhesion, but only in thiol containing formulations. This is a result of the decrease in T_gs and modulus of the films with the addition of mercaptans, thus providing better contact with the substrate in comparison to non-thiol containing formulations.     

Big Blue gets beaten: the technological and political controversyof the first large Swedish computerization project in a rhetoric oftechnology perspective

This article analyzes the rhetoric used in the Datasaab-IBM controversy when the first computerized national register and taxation system was created in the early 1960s. The aim is to understand how Datasaab could establish a new technological frame and at the same time grow into what became Sweden's first big computer manufacturer     

Using a molten organic conducting material to infiltrate a nanoporous semiconductor film and its use in solid-state dye-sensitized solar cells

We describe a method to fill thin films of nanoporous TiO₂ with solid organic hole-conducting materials and demonstrate the procedure specifically for use in the preparation of dye-sensitized solar cells. Cross-sections of the films were investigated by scanning electron microscopy and it was observed that a hot molten organic material fills pores that are 10 μm below the surface of the film. We characterized the incident photon to current conversion efficiency properties of the solid TiO₂/organic dye/organic hole-conductor heterojunctions and the spectra show that the dye is still active after the melting process.     

Load sharing between austenite and ferrite in a duplex stainless steel during cyclic loading

The load sharing between phases and the evolution of micro- and macrostresses during cyclic loading has been investigated in a 1.5-mm cold-rolled sheet of the duplex stainless steel SAF 2304. X-ray diffraction (XRD) stress analysis and transmission electron microscopy (TEM) show that even if the hardness and yield strength are higher in the austenitic phase, more plastic deformation will occur in this phase due to the residual microstresses present in the material. The origin of the microstresses is the difference in coefficients of thermal expansion between the two phases, which leads to tensile microstresses in the austenite and compressive microstresses in the ferrite. The microstresses were also found to increase from 50 to 140 MPa in the austenite during the first 100 cycles when cycled in tension fatigue with a maximum load of 500 MPa. The cyclic loading response of the material was, thus, mainly controlled by the plastic properties of the austenitic phase. It was also found that initial compressive macrostresses on the surface increased from −40 to 50 MPa during the first 10³ cycles. After the initial increase of microstresses and macrostresses, no fading of residual stresses was found to occur for the following cycles. A good correlation was found between the internal stress state and the microstructure evolution. The change in texture during cyclic fatigue showed a sharpening of the deformation texture in the ferritic phase, while no significant changes were found in the austenitic phase.