Growth of nanocomposite films: From dynamic roughening to dynamic smoothening

This paper reports several new findings on the breakdown of dynamic roughening in thin film growth. With increasing energy flux of concurrent ion impingement during pulsed DC sputtering, a transition from dynamic roughening to dynamic smoothening is observed in the growth behavior of TiC/a-C nanocomposite films. The nanocomposite films show a negative growth exponent and ultra-smoothness (RMS roughness ～0.2 nm at a film thickness of 1.5 μm). Based on high-resolution cross-sectional transmission electron microscopy observations we conclude that during growth an amorphous front layer of 2 nm covers the nanocomposite film and suppresses the influence of nanocrystallites on the roughness evolution of the nanocomposite films. We were able to predict the evolution of surface roughness based on a linear equation of surface growth which contains two diffusivity parameters that control the atomic mobility along the growing outer surface. The model is in good agreement with atomic force microscopy measurements of roughness evolution.     

Factors influencing the processing and technological properties of laminates based on phenolic resin impregnated papers

High quality decorative laminate panels typically consist of two major types of components: the surface layers comprising décor and overlay papers that are impregnated with melamine-based resins, and the core which is made of stacks of kraft papers impregnated with phenolic (PF) resin. The PF-impregnated layers impart superior hydrolytic stability, mechanical strength and fire-resistance to the composite. The manufacturing involves the complex interplay between resin, paper and impregnation/drying processes. Changes in the input variables cause significant alterations in the process characteristics and adaptations of the used materials and specific process conditions may, in turn, be required. This review summarizes the main variables influencing both processability and technological properties of phenolic resin impregnated papers and laminates produced therefrom. It is aimed at presenting the main influences from the involved components (resin and paper), how these may be controlled during the respective process steps (resin preparation and paper production), how they influence the impregnation and lamination conditions, how they affect specific aspects of paper and laminate performance, and how they interact with each other (synergies).     

Characterisation of physico-mechanical properties and degradation potential of calcium alginate beads for use in embolisation

High molecular weight alginate beads with 59% mannuronic acid content or 68% guluronic acid were prepared using a droplet generator and crosslinked in calcium chloride. The alginate beads were compared to current embolisation microspheres for compressibility and monitored over 12 weeks for size and weight change at 37°C in low volumes of ringers solutions. A sheep uterine model was used to analyse bead degradation and inflammatory response over 12 weeks. Both the in vitro and in vivo data show good delivery, with a compressibility similar to current embolic beads. In vitro, swelling was noted almost immediately and after 12 weeks the first signs of degradation were noted. No difference was noted in vivo. This study has shown that high molecular weight alginate gel beads were well tolerated by the body, but beads associated with induced thrombi were susceptible to inflammatory cell infiltration. The beads were shown to be easy to handle and were still observable after 3 months in vivo. The beads were robust enough to be delivered through a 2.7 Fr microcatheter. This study has demonstrated that high molecular weight, high purity alginate bead can be considered as semi-permanent embolisation beads, with the potential to bioresorb over time.     

The social network among engineering design teams and their creativity: A case study among teams in two product development programs

Since the creative product development task requires the teams to combine and integrate input from multiple other teams, the team’s structure of interaction is an important determinant of their creativity. In this study we investigate different structural aspects of social networks of such team’s and their creativity within two multinational product development programs (PDPs). There are two main results. First, teams with a wider range of informational links are better to realize creative novel and feasible output. Second, in contrast to prior findings our results indicate that network efficiency and the creativity of teams relate negatively. This suggests that direct contacts contribute much more to creativity than open network structures. In managerial terms our investigation indicates that the network structure of teams in PDPs is an important issue to consider when designing such programs and that tools should be available to assist their direct interaction.     

Texture in Melt-Processed Bi-2212

The high temperature superconducting phaseBi_2.2Sr_2.055Ca_0.95Cu₂O_x (Bi-2212) decomposes peritectically when heated above itssolidus temperature and reforms during slow cooling from the partiallymolten state. In thick films of 60 µm the Bi-2212 grains grow directlyfrom the melt when cooled at a rate of 5 K/h in oxygen atmosphere. Theorientation of the nuclei in the melt is random. After nucleation the grainsgrow anisotropically, leading to a mica- or platelet-like morphology. Upongrowth the Bi-2212 platelets encounter several obstacles, i.e. the sampleboundaries, second phase grains and other platelets. Various reactions occurwhen their growth is hindered. They stop growing, change the direction ofgrowth or even grow through the obstacle. A mechanism is proposed whichallows small grains to turn themselves into a favorable orientation at theirinitial stage of growth. At the end of the partial melting process, thesemechanisms lead to a textured microstructure in thick films.     

A novel MR-compatible sensor to assess active medical device safety: stimulation monitoring,rectified radio frequency pulses,and gradient-induced voltage measurements

Purpose

To evaluate the function of an active implantable medical device (AIMD) during magnetic resonance imaging (MRI) scans. The induced voltages caused by the switching of magnetic field gradients and rectified radio frequency (RF) pulse were measured, along with the AIMD stimulations.

Materials and methods

An MRI-compatible voltage probe with a bandwidth of 0–40 kHz was designed. Measurements were carried out both on the bench with an overvoltage protection circuit commonly used for AIMD and with a pacemaker during MRI scans on a 1.5 T (64 MHz) MR scanner.

Results

The sensor exhibits a measurement range of?±?15 V with an amplitude resolution of 7 mV and a temporal resolution of 10 µs. Rectification was measured on the bench with the overvoltage protection circuit. Linear proportionality was confirmed between the induced voltage and the magnetic field gradient slew rate. The pacemaker pacing was recorded successfully during MRI scans.

Conclusion

The characteristics of this low-frequency voltage probe allow its use with extreme RF transmission power and magnetic field gradient positioning for MR safety test of AIMD during MRI scans.

     

Heavy metal levels in Belgium: A five year survey

Daily average levels of Pb, Zn, Cd, Ba, V, Ni, Mn, Cu, Cr and Fe were routinely determined at fifteen different monitoring stations during the period May 1972–April 1977. Sampling on Whatman 41 cellulose filters was done by means of a specially designed high-volume sampler, while elemental analysis was based on emission spectrography. The most important statistical results for the elements under investigation are summarized and discussed.     

An assessment of the sustainable energy investments in the framework of the EU–GCC cooperation

The cooperation between the European Union (EU) and the Gulf Cooperation Council (GCC) should be broadened, deepened and become more interactive due to GCC states’ accession to the Kyoto protocol in 2005. Nowadays, the GCC states start putting climate change and its business opportunities on the top of their priorities’ list towards the accomplishment of the sustainable development goals. However, the level of development of sustainable energy investments (renewable energy, CO₂ sequestration and rational use of energy) is low until now in the GCC. For the above reason, the assessment of appropriate investments needs to be taken into account both by the governments in order to design the appropriate framework for supporting them and the project investors to identify the commercially profitable ones. In this framework, the aim of this paper is the identification and assessment of sustainable energy investments in the framework of the EU–GCC co-operation.