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Ionic liquids (ILs) are recyclable acid catalysts for transesterification reactions. In the present study, different acidic ILs were examined in this reaction, with special focus on their recyclability. Furthermore, the IL-catalyzed transesterification reaction was realized in continuous operation. A miniplant reactor with technically representative design and operating characteristics was used for this study. The applied rig has a volume of 5 L and an external thermosyphon reboiler. The miniplant reactor can be operated in batch and in continuous mode. ILs functionalized with a sulfonic acid group were found to be the most suitable IL catalysts for the transesterification reactions under investigation. Using these ILs, reaction rates as high as for H2SO4 could be realized. Moreover, the IL catalyst was demonstrated to be active for at least 1000 h of operation time. [ABSTRACT FROM AUTHOR]

Surface structures with a well-defined shape and dimension in a staggered arrangement were evaluated in terms of their capability to improve the single-phase convective heat transfer in channels with small dimensions. Two evaluation criteria were used: (i) the thermal efficiency index, defined by the ratio of heat transfer enhancement and pressure drop increase, and (ii) the irreversible entropy generation which is determined by the entropy production rates through heat conduction and dissipation. Beside experimental measurements, parametric studies were performed using computational fluid dynamics to establish the entropy generation rates within the heated flow channel. [ABSTRACT FROM AUTHOR]

The application of ultrasound during the batch-wise as well as continuous crystallization of lipid nanoparticles is reported. For the latter, a micro heat exchanger is modified, allowing the inline application of ultrasound to promote the α-to-β transformation of the lipid nanoparticles. Ultrasonication during batch crystallization is carried out in an ultrasonic bath. While for batch processing the application of ultrasound leads to an increase of the fraction of stable β-polymorph according to differential scanning calorimetry measurements, no significant increase is found for continuous operation. This is a result of one or both of the following effects: The residence time in the continuous micro heat exchanger is approximately 1 s and thus possibly too short for significant influences on the polymorphism or crystallization. Additionally, the ultrasound is induced indirectly to the product side and thus reduced. [ABSTRACT FROM AUTHOR]

Diffusion coefficients of different sugars and the sugar alcohol sorbitol have been determined by two different experimental setups: mass transfer through a flat membrane in a diffusion cell and effusion experiments with beads in a batch stirred vessel. Diffusion experiments show highly consistent data with low uncertainties and high regression coefficients, while effusion experiments suffer from larger experimental uncertainties. For the diffusion through a chitosan membrane at 25 °C, typically one-third of the free molecular diffusion coefficient is found, whereas at 40 °C only one-quarter of it is reached. The influence of molecular size, structure, and temperature on the transport properties is discussed in detail. [ABSTRACT FROM AUTHOR]

Analysis of a German database comprising a total of 54 patients with neonatal manifestations of persistent hyperinsulinism revealed 5 patients in whom hyperinsulinism was associated with additional clinical symptoms, suggesting an underlying syndromal disorder. Three of the patients presented with a similar yet unknown clinical entity characterized by severe psychomotor retardation, chronic pulmonary disease, hypothyroidism and congenital heart defects. A fourth patient was affected by severe congenital central hypoventilation syndrome. The fifth patient presented with Beckwith-Wiedemann syndrome, with unusually severe and persistent hyperinsulinism requiring subtotal pancreatectomy. [ABSTRACT FROM AUTHOR]