Mechanisms and Control of Self-Emulsification upon Freezing and Melting of Dispersed Alkane Drops

Emulsification requires drop breakage and creation of a large interfacial area between immiscible liquid phases. Usually, high-shear or high-pressure emulsification devices that generate heat and increase the emulsion temperature are used to obtain emulsions with micrometer and submicrometer droplets. Recently, we reported a new, efficient procedure of self-emulsification (Tcholakova et al. Nat. Commun. 2017, 8, 15012), which consists of one to several cycles of freezing and melting of predispersed alkane drops in a coarse oil-in-water emulsion. Within these freeze-thaw cycles of the dispersed drops, the latter burst spontaneously into hundreds and thousands of smaller droplets without using any mechanical agitation. Here, we clarify the main factors and mechanisms, which drive this self-emulsification process, by exploring systematically the effects of the oil and surfactant types, the cooling rate, and the initial drop size. We show that the typical size of the droplets, generated by this method, is controlled by the size of the structural domains formed in the cooling-freezing stage of the procedure. Depending on the leading mechanism, these could be the diameter of the fibers formed upon drop self-shaping or the size of the crystal domains formed at the moment of drop-freezing. Generally, surfactant tails that are 0-2 carbon atoms longer than the oil molecules are most appropriate to observe efficient self-emulsification. The specific requirements for the realization of different mechanisms are clarified and discussed. The relative efficiencies of the three different mechanisms, as a function of the droplet size and cooling procedure, are compared in controlled experiments to provide guidance for understanding and further optimization and scale-up of this self-emulsification process

Bottom-Up Synthesis of Polymeric Micro- and Nanoparticles with Regular Anisotropic Shapes

Shape-anisotropic polymeric micro- and nanoparticles are of significant interest for the development of novel composite materials, lock-and-key assemblies, and drug carriers. Currently, syntheses require external confinement in microfluidic devices or lithographic techniques associated with significant infrastructure and low productivity, so new methods are necessary to scale-up such production efficiently. Here we report bottom-up polymerization of regular shape-anisotropic particles (polygonal platelets with different numbers of edges, with and without protruding asperities, and fibrilar particles with controllable aspect ratios), with size control over 4 orders of magnitude (∼50 nm-1 mm). Polymerization also enables the study of much smaller shapes than could previously be studied in water suspensions, and we study the fundamental limits of the self-shaping transition process driving these transformations for monomer oil droplets of stearyl methacrylate (SMA) monomer oil. We show the method is compatible with a variety of polymerizing monomers and functional modifications of the particles (e.g., composites with magnetic nanoparticles, oil-soluble additives, etc.). We also describe postsynthetic surface modifications that lead to hierarchical superstructures. The synthesis procedure has great potential in efficient nanomanufacturing as it can achieve scalable production of the above shapes in a wide range of sizes, with minimum infrastructure and process requirements and little maintenance of the equipment

The clinical relevance of oliguria in the critically ill patient : Analysis of a large observational database

Funding Information: Marc Leone reports receiving consulting fees from Amomed and Aguettant; lecture fees from MSD, Pfizer, Octapharma, 3 M, Aspen, Orion; travel support from LFB; and grant support from PHRC IR and his institution. JLV is the Editor-in-Chief of Critical Care. The other authors declare that they have no relevant financial interests. Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Urine output is widely used as one of the criteria for the diagnosis and staging of acute renal failure, but few studies have specifically assessed the role of oliguria as a marker of acute renal failure or outcomes in general intensive care unit (ICU) patients. Using a large multinational database, we therefore evaluated the occurrence of oliguria (defined as a urine output 16 years) patients in the ICON audit who had a urine output measurement on the day of admission were included. To investigate the association between oliguria and mortality, we used a multilevel analysis. Results: Of the 8292 patients included, 2050 (24.7%) were oliguric during the first 24 h of admission. Patients with oliguria on admission who had at least one additional 24-h urine output recorded during their ICU stay (n = 1349) were divided into three groups: transient - oliguria resolved within 48 h after the admission day (n = 390 [28.9%]), prolonged - oliguria resolved > 48 h after the admission day (n = 141 [10.5%]), and permanent - oliguria persisting for the whole ICU stay or again present at the end of the ICU stay (n = 818 [60.6%]). ICU and hospital mortality rates were higher in patients with oliguria than in those without, except for patients with transient oliguria who had significantly lower mortality rates than non-oliguric patients. In multilevel analysis, the need for RRT was associated with a significantly higher risk of death (OR = 1.51 [95% CI 1.19-1.91], p = 0.001), but the presence of oliguria on admission was not (OR = 1.14 [95% CI 0.97-1.34], p = 0.103). Conclusions: Oliguria is common in ICU patients and may have a relatively benign nature if only transient. The duration of oliguria and need for RRT are associated with worse outcome.publishersversionPeer reviewe

Temporal changes in the epidemiology, management, and outcome from acute respiratory distress syndrome in European intensive care units: a comparison of two large cohorts

Background: Mortality rates for patients with ARDS remain high. We assessed temporal changes in the epidemiology and management of ARDS patients requiring invasive mechanical ventilation in European ICUs. We also investigated the association between ventilatory settings and outcome in these patients. Methods: This was a post hoc analysis of two cohorts of adult ICU patients admitted between May 1–15, 2002 (SOAP study, n = 3147), and May 8–18, 2012 (ICON audit, n = 4601 admitted to ICUs in the same 24 countries as the SOAP study). ARDS was defined retrospectively using the Berlin definitions. Values of tidal volume, PEEP, plateau pressure, and FiO2 corresponding to the most abnormal value of arterial PO2 were recorded prospectively every 24 h. In both studies, patients were followed for outcome until death, hospital discharge or for 60 days. Results: The frequency of ARDS requiring mechanical ventilation during the ICU stay was similar in SOAP and ICON (327[10.4%] vs. 494[10.7%], p = 0.793). The diagnosis of ARDS was established at a median of 3 (IQ: 1–7) days after admission in SOAP and 2 (1–6) days in ICON. Within 24 h of diagnosis, ARDS was mild in 244 (29.7%), moderate in 388 (47.3%), and severe in 189 (23.0%) patients. In patients with ARDS, tidal volumes were lower in the later (ICON) than in the earlier (SOAP) cohort. Plateau and driving pressures were also lower in ICON than in SOAP. ICU (134[41.1%] vs 179[36.9%]) and hospital (151[46.2%] vs 212[44.4%]) mortality rates in patients with ARDS were similar in SOAP and ICON. High plateau pressure (> 29 cmH2O) and driving pressure (> 14 cmH2O) on the first day of mechanical ventilation but not tidal volume (> 8 ml/kg predicted body weight [PBW]) were independently associated with a higher risk of in-hospital death. Conclusion: The frequency of and outcome from ARDS remained relatively stable between 2002 and 2012. Plateau pressure > 29 cmH2O and driving pressure > 14 cmH2O on the first day of mechanical ventilation but not tidal volume > 8 ml/kg PBW were independently associated with a higher risk of death. These data highlight the continued burden of ARDS and provide hypothesis-generating data for the design of future studies

Multilayer Formation in Self-Shaping Emulsion Droplets.

In several recent studies, we showed that micrometer-sized oil-in-water emulsion droplets from alkanes, alkenes, alcohols, triglycerides, or mixtures of these components can spontaneously "self-shape" upon cooling into various regular shapes, such as regular polyhedrons, platelets, rods, and fibers ( Denkov , N. , Nature 2015 , 528 , 392 ; Cholakova , D. , Adv. Colloid Interface Sci. 2016 , 235 , 90 ). These drop-shape transformations were explained by assuming that intermediate plastic rotator phase, composed of ordered multilayers of oily molecules, is formed beneath the drop surface around the oil-freezing temperature. An alternative explanation was proposed ( Guttman , S. , Proc. Natl. Acad. Sci. USA 2016 113 , 493 ; Guttman , S. , Langmuir 2017 , 33 , 1305 ), which is based on the assumption that the oil-water interfacial tension decreases to very low values upon emulsion cooling. Here, we present new results, obtained by differential scanning calorimetry (DSC), which quantify the enthalpy effects accompanying the drop-shape transformations. Using optical microscopy, we related the peaks in the DSC thermograms to the specific changes in the drop shape. Furthermore, from the enthalpies measured by DSC, we determined the fraction of the intermediate phase involved in the processes of drop deformation. The obtained results support the explanation that the drop-shape transformations are intimately related to the formation of ordered multilayers of alkane molecules with thickness varying between several and dozens of layers of alkane molecules, depending on the specific system. The new results provide the basis for a rational approach to the mechanistic explanation and to the fine control of this fascinating and industrially relevant phenomenon

RESPONSE OF DURUM WHEAT (TRITICUM DURUM DESF.) CULTIVAR PROGRESS TO FOLIAR FEEDING

During the period 2008-2010 the response of durum wheat cultivar Progress, grown on Pellic Vertisols at the field of the Field Crops Institute, Chirpan, Bulgaria, to foliar feeding was studied. The new organic, systematic and complex fertilizers - Icyactive, Icyamin, Start-up, Fertileader Alfa, Fertileader BPK and Fertileader Vital 954 were tested. Fertilizers were applied twice during tillering - begining of stem elongation, alone and in combination with N120 fertilization. The results showed that the products influenced the durum wheat growth, productivity and grain quality. Additional grain yield after foliar application ranged from 122 to 430 kg.ha-1, which is 4.4-15.4 % above the control. Differences were stronger after a combination of foliar spraying and N fertilization - yields were in excess of 53.7-54.1 % and reached 4.30 t.ha-1 after fertilization with Icyactive + N120. The test weight of the grain was in the range of 79.70-80.23 kg/hl and was formed mainly under influence of the weather conditions. The 1000 kernel weight reached 57.7 g after Fertileader Vital 954 - 3 l/ha, which is 2.5 % above control. Vitreousness increased with 36.4-43.9 %, content of crude protein - with 22.0-30.7 % and wet gluten – with 17.9-25.7 % compared to control. From agronomic point of view liquid fertilizers can be successfully used for foliar feeding of durum wheat. Icyactive - 1 l/ha, Fertileader Alfa - 3 l/ha and Start-up - 3 l/ha manifested a very good effect