This study presents efficient geometric parameterisation techniques for the continuation power flow. The Jacobian matrix singularity is eliminated by the addition of the line equations which pass through the points in the plane determined by the variables loading factor and the sum of nodal voltage magnitudes, or angles, of all system buses. These techniques enable the complete tracing of P-V curves and the computation of the maximum loading point for any power system, including those with voltage instability problems that have the strong local characteristics, for which the global parameterisation techniques are considered inadequate. An efficient criterion to change the set of lines, based on the analysis of the total power mismatch evolution, is also defined. The obtained results show that the characteristics of Newton's conventional method are preserved and the convergence region around the Jacobian matrix singularity is enhanced. The computational time required to trace the P-V curve can also be reduced, without losing robustness, when the Jacobian matrix is updated only after the system undergoes a significant change.

The traditional use of propolis does not necessarily guarantee its safety. The evaluation of the safety of bioactive natural products should always be considered together with the evaluation of the activity.

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The present study focuses on the characterization of the cytotoxic profile on NIH3T3 mouse embryonic fibroblasts of solid lipid nanoparticles (SLN) optimized by a 2 2 full factorial design for skin administration. To build up the surface response charts, a design of experiments (DoE) based on 2 independent variables was used to obtain an optimized formulation. The effect of the composition of lipid and water phases on the mean particle size (z-AVE), polydispersity index (PdI) and zeta potential (ZP) was studied. The developed formulations were composed of 5.0% of lipid phase (stearic acid (SA), behenic alcohol (BA) or a blend of SA:BA (1:1)) and 4.7% of surfactants (soybean phosphatidylcholine and poloxamer 407). In vitro cytotoxicity using NIH3T3 fibroblasts was performed by MTT reduction assay. This factorial design study has proven to be a useful tool in optimizing SLN (z-AVE ∼ 200 nm), which were shown to be non-cytotoxic. The present results highlight the benefit of applying statistical designs in the preparation and optimization of SLN formulations.

The conventional Newton and fast decoupled power flow methods are considered inadequate for obtaining the maximum loading point of power systems due to ill-conditioning problems at and near this critical point. At this point, the Jacobian matrix of the Newton method becomes singular. In addition, it is widely accepted that the P-V and Q-decoupling assumptions made for the fast decoupled power flow formulation no longer hold. However, in this paper, it is presented a new fast decoupled power flow that becomes adequate for the computation of the maximum loading point by simply using the reactive power injection of a selected PV bus as a continuation parameter. Besides, fast decoupled methods using V and as parameters and a secant predictor are also presented. These new versions are compared to each other with the purpose of pointing out their features, as well as the influence of reactive power and transformer tap limits. The results obtained for the IEEE systems (14 and 118 buses) show that the characteristics of the conventional method are enhanced and the region of convergence around the singular solution is enlarged. Index Terms-Continuation power flow, fast decoupled power flow, maximum loading point, voltage collapse.

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