National laboratory-based surveillance system for antimicrobial resistance: a successful tool to support the control of antimicrobial resistance in the Netherlands

An important cornerstone in the control of antimicrobial resistance (AMR) is a well-designed quantitative system for the surveillance of spread and temporal trends in AMR. Since 2008, the Dutch national AMR surveillance system, based on routine data from medical microbiological laboratories (MMLs), has developed into a successful tool to support the control of AMR in the Netherlands. It provides background information for policy making in public health and healthcare services, supports development of empirical antibiotic therapy guidelines and facilitates in-depth research. In addition, participation of the MMLs in the national AMR surveillance network has contributed to sharing of knowledge and quality improvement. A future improvement will be the implementation of a new semantic standard together with standardised data transfer, which will reduce errors in data handling and enable a more real-time surveillance. Furthermore, the

Numerical and experimental study of transferred arc in argon

The bidimensional model of the electric arc is enhanced with the plasma–electrodes interaction to predict the properties and the energy distribution of an argon arc operating with current intensities between 100 and 200A and electrode gaps of 10 and 20 mm. An adaptive numerical insulation is applied to the cathode, to properly simulate its thermionic emission mechanism and overcome the dependence on empirical distributions of the current density at its tip. The numerical results are quantitatively compared with the data obtained from calorimetric and spectroscopical measurements, performed on a device which generates a transferred arc between a water cooled copper anode and a thoriated tungsten cathode enclosed in a stainless steel chamber. The calculation of the heat fluxes towards the electrodes permits to determine the amount of power delivered to each component of the arc system (the anode, the cathode assembly and the chamber) and to evaluate the overall efficiency of the process for different configurations. The agreement between theory and data, over the range of parameters investigated, is sensible both in the temperature profiles and in the energy distributions. In such configurations, the conduction from the hot gas is the most relevant term in the overall heat transferred to the anode, but it is the electron transfer which rules the heat transfer in the arc attachment zone. The arc attachment radius is also dependent on the process parameters and increases with the arc current (from approximately 5mm at 100A to 7mm at 200 A) and the arc length. However the maximum heat flux reached on the axis decreases increasing the gap between the electrodes, although more power is delivered to the anode due to the radial spreading of the plasma. A 10mm 200A argon arc releases to the anode about 2.6kW, which corresponds to 75% of the total arc power available. If the arc is extended to 20mm the power transferred rises by nearly 350 W, but the overall efficiency drops to 65% due to the increased losses towards the chamber. The power delivered to the anode increases almost linearly with the arc current, presenting a slope of about 15WA−1, independent of the arc length

LOADING AND RADIATION EFFECTS IN PLASMA JET MODELLING

L'effet de l'interaction plasma-particules et de la présence de vapeurs métalliques provenant de l'évaporation des particules est étudié à l'aide d'un modèle mathématique. On trouve que le chauffage des particules ainsi que l'augmentation du rayonnement du aux vapeurs métalliques provoquent un refroidissement très important du plasma. La taille des particules a un effet déterminant sur ces deux phénomènes.The plasma-particle interaction and the effect of the presence of metallic vapors from the evaporating particles is studied using a mathematical model. It is found that the particle heating and the increase in radiative losses due to the metallic vapors are responsible for the important cooling of the plasma. The particle size is a critical parameter for these two effects

Flow and temperature fields in a free discharge inductively coupled plasma

Computations were made of the flow and temperature fields in an inductively coupled argon plasma at atmospheric pressure under confined and free discharge conditions. The model takes into account gravity effects and swirl in the sheath gas. Natural convection was found to have a negligible effect on the flow and temperature fields under confined discharge conditions but a significant effect for the free discharge. The back flow in the discharge was substantially reduced in the presence of swirl for swirl velocities over the range 0-50 m/s. Also with a mode-rate increase in swirl, the conduction heat flux to the wall decreased but increased with the further increase in swirl. From an overall energy balance point of view, conductive heat flux to the wall of the plasma confinement tube was substantially lower for a free plasma discharge compared to that for a confined plasma

The Treatment of Water-Based Toxic Waste Using Induction Plasma Technology

A study of the treatment of liquid wastes in a radio frequency (rf) induction plasma reactor is reported. Ethylene glycol was used as a surrogate for the waste because of safety considerations. Thermodynamic analyses demonstrated complete and safe decomposition at the conditions studied. The solution was injected axially into the center of an argon–oxygen plasma operated at a plate power of 50 kW to study blast atomization and operating conditions. A factorial analysis revealed, at a confidence level of 0.99, that both reduction of pressure and liquid flow rate increase the destruction and removal efficiency (DRE) and that a higher plate power increased DRE