This study deals with an assessment of the thermodynamic description of the Yb–Sn system using the CALPHAD technique [ 2 ]. The thermodynamic parameters involved in the models are optimized from the experimental thermodynamic and
, blended cement contains both cement clinker (high activity) and SCM (low activity) or inert fillers. Hydration process of blended cement can be optimized by arranging the size range of clinker and SCMs (or inert fillers) according to their hydration
Authors:K. Sarma, S. Sabharwal, A. Kalurkar, C. Chaudhary, S. Khader, R. Deshpande, and A. Majali
Radiation crosslinked LDPE O rings, an inexpensive substitute for PTFE and polysilicone gaskets in high temperature applications, are widely used in the industry. Radiation crosslinking of LDPE O rings, in the finished form was carried out at the 20 kW-2 MeV, ILU — 6 type EB facility installed at the Bhabha Atomic Research Centre, Bombay to establish irradiation technique for large scale production and for an adequate and uniform dose delivery. Two irradiation geometries viz. flat bed and rotating spindle were chosen for batch processing and optimisation of process parameters. The laboratory analysis and thein situ performance showed that a minimum of 65 % gel-content is needed in the irradiated rings and that an absorbed dose of about 200 kGy is adequate to meet the industrial standards. Rotating spindle technique was found to have an edge over flat bed irradiation in terms of dose uniformity and throughput. This paper gives an account of the work carried out to optimise the process parameters for both the geometries.
Authors:N. Papadopoulos, G. Hatzakis, A. Salevris, and N. Tsagas
A combination of special techniques has been developed for optimization of experimental conditions in order to improve the analytical capability, to facilitate automation and to broaden the applicability of instrumental neutron activation analysis. The techniques used are: (1) compensation for the rapid radioactive decay of short-lived nuclides with the increase of the counting efficiency by automatic source movement to the detector during the counting period, to minimize count rate variations and to prolong the counting period, (2) repeated cyclic and cumulative activation to improve the counting statistics, (3) instrumental correction of counting losses at high and varying count rates by a loss-free counting system and (4) differentiation of the reactor neutron spectrum to enhance the counts from the nuclides of interest by reducing matrix interferences. By optimized combination and automation of these techniques significant improvement of the capability of instrumental neutron activation analysis can be achieved.
Authors:René Becker, Sebastiaan (Bas) A.M.W. van den Broek, Pieter J. Nieuwland, Kaspar Koch, and Floris P.J.T. Rutjes
To expand the knowledge base for fundamental organic reactions in continuous flow, the α-bromination of acetophenone was successfully transformed from a known batch procedure to a continuous flow process in 99 % yield through D-optimal optimisation and subsequent scale-up of the validated optimum. Using a preparative scale system, a space–time yield of 0.26 kg/m3/s (comparable literature batch reaction 0.24 kg/m3/s) was achieved under conditions suitable for laboratory and small-scale industrial application where high yield or purity is required, e.g., when expensive substrates are used.
Several studies were carried out to optimise rapid tritium analysis in fresh waters by ultra-low background liquid scintillation.
These included the optimisation of (1) sample/scintillant ratio, (2) pulse shape analysis, and (3) pulse-amplitude comparator,
and studies concerning (1) the combination scintillant/vial and (2) the effect of chemiluminescence. The proposed method involves
the mixing of 8 ml sample with 12 ml scintillation cocktail Ultima Gold AB in Zinsser low diffusion vials. These are stored
during one day before counting in order to reduce chemiluminescence. The minimum detectable activity achieved was 2.2 Bq·l−1 for a total counting time of 360 minutes. In order to test the method, tritium was determined in Ebro river samples.