Error-control and processes optimization of (223/224)Ra measurement using Delayed Coincidence Counter (RaDeCC).

RaDeCC has proved to be a precise and standard way to measure (224)Ra and (223)Ra in water samples and successfully made radium a tracer of several environmental processes. In this paper, the relative errors of (224)Ra and (223)Ra measurement in water samples via a Radium Delayed Coincidence Count system are analyzed through performing coincidence correction calculations and error propagation. The calculated relative errors range of 2.6% ∼ 10.6% for (224)Ra and 9.6% ∼ 14.2% for (223)Ra. For different radium activities, effects of decay days and counting time on final radium relative errors are evaluated and the results show that these relative errors can decrease by adjusting the two measurement factors. Finally, to minimize propagated errors in Radium activity, a set of optimized RaDeCC measurement parameters are proposed.

Optimization of Preparation for Venlafaxine Hydrochloride W/O Emulsion by Central Composite Design-Response Surface Methodology / 医药导报

Objective To optimize the formulations of venlafaxine hydrochloride ( VH ) emulsions by using central composite design-response surface methodology. Methods The effect of amounts of Arlacel P135, VH, PEG-400, and NaCl on the emulsion viscosity, centrifugation breakage, and mean diameter was systemically investigated, respectively. The desirable formulation that combining these three response variables was constructed. Linear equations and a second-order polynomial equation were fitted to the data, and the outcome equation was used to predict the responses in the optimal region. Results There was a quantitative relationship between 4 factors and 3 evaluation indexes and evaluation the “desirability” . The optimal formulation of the VH emulsion were as follows:taking 0. 48 g of Arlacel P135, 0. 40 g of VH, 0. 26 g of PEG-400, and 0. 025 g of NaCl. The experimental values of the response variables were highly closed to the predict values. Conclusion The model presents good prediction and can be used to optimize the preparation of VH emulsion, which obtaining stable W/O emulsion.