Interactions of phase equilibria, jet fluid dynamics and mass transfer during supercritical antisolvent micronization

Supercritical antisolvent (SAS) precipitation has been successfully used in the micronization of several compounds. Nevertheless, the role of high-pressure vapor–liquid equilibria, jet fluid dynamics and mass transfer in determining particle size and morphology is still debated. In this work, CO2 has been adopted as supercritical antisolvent and elastic light has been used to acquire information on jet fluid dynamics using thin wall injectors for the investigation of the liquid solvents acetone and DMSO at operating conditions of 40 °C in the pressure range between 6 and 16 MPa. The results show that two-phase mixing after jet break-up is the phenomenon that characterizes the jet fluid dynamics at subcritical conditions. When SAS is performed at supercritical conditions a transition between multi-phase and single-phase mixing is observed by increasing the operating pressure. Single-phase mixing is due to the very fast disappearance of the interfacial tension between the liquid solvent and the fluid phase in the precipitator. The transition between these two phenomena depends on the operating pressure, but also on the viscosity and the surface tension of the solvent. Indeed, single-phase mixing has been observed for acetone very near the mixture critical point, whereas DMSO showed a progressive transition for pressures of about 12 MPa. In the second part of the work, a solute was added to DMSO to study the morphology of the microparticles formed during SAS precipitation at the different process conditions, to find a correlation between particle morphology and the observed jet. Expanded microparticles were obtained working at subcritical conditions; whereas spherical microparticles were obtained operating at supercritical conditions up to the pressure where the transition between multi- and single-phase mixing was observed. Nanoparticles were obtained operating far above the mixture critical pressure. The observed particle morphologies have been explained considering the interplay among high-pressure phase equilibria, fluid dynamics and mass transfer during the precipitation process

Collecting Evidence Through Access to Competition Authoritiess Files Interplay or Potential Conflicts between Private and Public Enforcement Proceedings?

Information asymmetry between claimants seeking damages for competition law violations and the alleged infringing undertaking(s) is a key problem in the development of private antitrust enforcement because it often prevents successful actions for damages. The Damages Directive is a step forward in the facilitation of access to evidence relevant for private action claims. Its focus lies on, inter alia, 3rd party access to files in proceedings conducted by national competition authorities (NCAs). The harmonization was triggered by the inconsistencies in European case-law and yet the uniform rules on access to documents held in NCAs’ files proposed in the Damages Directive seem to follow a very stringent approach in order to protect public competition law enforcement. The article summarizes the most relevant case-law and new provisions of the Damages Directive and presents practical issues with respect to its implementation from the Polish perspective

Dynamic and static characteristics of drug dissolution in supercritical CO2 by infrared spectroscopy : measurements of acetaminophen solubility in a wide range of state parameters

In this work we use infrared spectroscopy to investigate solubility properties of a bioactive substance in supercritical CO2 (scCO2). By using acetaminophen as a model compound, we show that the method can provide high sensitivity that makes it possible to study solubility at small concentrations, up to 10-6 mol·L-1. This method also allows one to investigate the kinetics of the dissolution process in supercritical solvent. Our measurements at two different points of the (p, T) plane ((40 MPa, 373 K) and (40 MPa, 473 K)) have shown significant difference in the kinetic mechanisms of acetaminophen dissolution at these two states: at higher temperature the dissolution process in scCO2 has two steps: (i) "fast" step when the acetaminophen concentration in scCO2 quickly reaches (70 to 80) % of the saturation level and (ii) a subsequent "slow" step where the acetaminophen concentration slowly increases up to the saturation level. However, at lower temperature, the dissolution process has only one, "slow" step