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.     

Prozessintegriertes Trocknen von Rohwaren in den Werken der Luzenac Naintsch Mineralwerke GmbH

Process chain optimisation at the Luzenac Naintsch production sites enabled to dry the ore almost without use of primary energy. Main parts of production are dried without additional energy during the mechanical milling process carried out on roller mills, ball mills as well as on jet mills. In case a separate drying before the fine sieving process is necessary, the drying is done by using waste heat out of other processes.     

A review of the effects of pollution and water scarcity on the stream biota of an intermittent Mediterranean basin

This review presents the main results of a 10‐year research study conducted in a Mediterranean intermittent basin (Evrotas River). By assembling the main outcomes of past and ongoing research projects, this study provides an overview of multiple stressor effects, with emphasis on water scarcity, focusing on hydro‐biogeochemical processes, as well as on spatial and temporal variations in benthic macroinvertebrates and fish fauna. The major impact in the basin has been the over‐exploitation of surface and groundwater resources, which, in combination with droughts, has resulted in the recurrent artificial desiccation of large parts of the hydrological network. The response to intermittency of the macroinvertebrate fauna is characterized by high resilience through various drought‐resistant evolutionary mechanisms, with assemblages recovering successfully after recurrent droughts. However, when pollution is evident in combination with drought, effects on benthic species richness, abundance, and assemblage structure can be severe. Similarly, pollution and water stress may result in massive fish mortalities due to hypoxic conditions, with fish populations requiring long periods to recover. However, the fish fauna appears to be relatively resilient to drought‐driven reach‐scale desiccation, and ultimately recovers, provided that aquatic refugia are available to supply colonists and that there are no physical barriers impeding recolonisation. Appropriate conservation measures are urgently required to address the effects of recurrent bouts of water stress, as well as of other stressors on the freshwater communities of the Evrotas River, both at the level of water management and of water policy and at the local and the national level.