Protein-stabilized emulsions and nanoemulsions

This presentation will summarize briefly our current understanding of the scientific and technological basis for the formation of emulsions containing micrometer and nanometer sized droplets, with applications in food, cosmetic and pharma industries [1-3]. The focus will be on protein-stabilized emulsions. Their specific features will be summarized in comparison to the surfactant- and particle-stabilized emulsions [3]. The subtle relations between the material characteristics of the emulsions (oil type, emulsifier, pH, etc.) and the optimal hydrodynamic conditions for emulsification will be discussed [3] in the context of obtaining emulsions with desired properties. Examples of appropriate mixtures of proteins with other emulsifiers (lipids, lysolipids, natural gums) will be given. The differences between oil-in-water and water-in-oil emulsions will be briefly discussed [4,5]. Special focus will be given on the recent advance in production of nanoemulsions using high pressure homogenizers, high viscosity of the continuous phase, and/or high oil volume fraction during emulsification [6,7]. Some new methods for self-emulsification will be briefly reviewed [8,9]. The basic physicochemical and hydrodynamic concepts will be illustrated by multiple examples with real systems. References: David Julian McClements, Food Emulsions: Principles, Practices, and Techniques, 3rd Edition, CRC Press, 2015. Andreas Håkansson, Emulsion Formation by Homogenization: Current Understanding and Future Perspectives, Annu. Rev. Food Sci. Technol. 10 (2019) 239–258 (review article). S. Tcholakova, N. D. Denkov, and A. Lips, Comparison of Solid Particles, Globular Proteins and Surfactants as Emulsifiers. Phys. Chem. Chem. Phys. 10 (2008) 1608-1627 (review article). N. Politova, S. Tcholakova, N. D. Denkov, Factors Affecting the Stability of Water-oil-water Emulsion Films. Colloids Surfaces A 522 (2017) 608–620. N. Politova, S. Tcholakova, S. Tsibranska, N. D. Denkov, K. Muelheims, Coalescence Stability of Water-in-Oil drops: Effects of Drop Size and Surfactant Concentration. Colloids Surfaces A 531 (2017) 32–39. S. Tcholakova, I. Lesov, K. Golemanov, N. Denkov, S. Judat, R. Engel, T. Daner, Efficient Emulsification of Viscous Oils at High Drop Volume Fraction. Langmuir 27 (2011) 14783-14796. D. Gazolu-Rusanova, I. Lesov, S. Tcholakova, N. Denkov, B. Ahtchi, Food grade nanoemulsion preparation by rotor-stator homogenization. Food Hydrocolloids (2019) under review. S. Tcholakova, Z. Valkova, D. Cholakova, Z. Vinarov, I. Lesov, N. D. Denkov, K. Smoukov, Efficient Self-Emulsification via Cooling-Heating Cycles. Nature Comm. 8 (2017) 15012. Zh. Valkova, D. Cholakova, S. Tcholakova, N. Denkov, S. K. Smoukov, Mechanisms and Control of Self-Emulsification upon Freezing and Melting of Dispersed Alkane Drops. Langmuir 33 (2017) 12155−12170

Determination of Fluoride by Precipitation of Lead Chlorofluoride: Comparison of Classical and Homogeneous Precipitation Methods

Optimal conditions for the homogeneous precipitation of lead chlorofluoride were investigated and the method was compared with the classical procedure. The most suitable reagent for the pH control of the homogeneous solution was found to be urea \\u27.ith ammonium acetate buffer. If the precipitate obtained by both procedures was allowed to stand overnight, homogeneous precipitation resulted with more accurate data

L’étape d’après. Travail et déclassement subjectif des réfugié·e·s en Bulgarie

L’article se propose d’interroger la problématique de « l’après », envisagé comme ce qui advient ultérieurement à la reconnaissance juridico-administrative des réfugié·e·s en Bulgarie et ce, à travers le prisme du travail. Dans un premier temps l’auteure présente les principaux éléments qui organisent la politique d’asile et la politique dite d’intégration en Bulgarie, en soulignant les effets qu’elles produisent sur l’expérience des réfugié·e·s. Dans un deuxième temps l’article explore pourquoi le travail se trouve être au cœur des attentes de reconnaissance qui émergent une fois obtenu le statut de réfugié·e. Dans un dernier temps, l’article développe une analyse du travail des réfugié·e·s et du travail pour les réfugié·e·s selon une approche sociologique intersectionnelle. On y examine la manière dont l’expérience et les attentes qui sont propres à la condition de réfugié·e modèlent ces deux types d’activité de travail.This article asks the following question: what do refugees become after having got legal and administrative recognition? In a first step, it analyzes the main features of the Bulgarian asylum policy and the so-called integration policy. It focuses on their effects on the refugee’s experience. In a second step, it explains why work is central in the recognitive expectations emerging after having been recognized as a refugee. In a last step, a sociological and intersectional approach to the work of and for refugees is elaborated. What is at stake is to show how these two types of working activities are shaped by experiences and recognitive expectations that are proper to the refugee condition.El artículo propone examinar la problemática del «después», vale decir considerar lo que adviene posteriormente al reconocimiento jurídico-administrativo de los refugiados en Bulgaria a través del prisma del trabajo. En primer lugar, la autora presenta los principales elementos que organizan la política de asilo y la llamada política de integración en Bulgaria, destacando los efectos que producen sobre la experiencia de los refugiados. En segundo lugar, el artículo explora las razones por las cuales el trabajo se ubica en el centro de las expectativas de reconocimiento que surgen una vez obtenido el estatuto de refugiado. Por último, el artículo desarrolla un análisis del trabajo de los refugiados, así como también para los refugiados recurriendo a un enfoque sociológico interseccional. Se examina la manera en que la experiencia y las expectativas propias de la condición de refugiado modelan esos dos tipos de actividad de trabajo

Working-class against their will: “Recognized” refugees in France and Bulgaria in the early twenty-first century

Drawing on a sociological study concerning “recognized” refugees in France and Bulgaria and their search for work, this article aims at opening a research field about the gender dimension of their relationship to work. The refugees who become workers generally experience this transformation as a loss of social and professional status that destabilizes their identity and amplifies the rupture with their habitual world that exile entails. The paper shows that these experiences of loss coincide with transformation in gender identifications (either destabilization or strengthening of “virile” or “feminine” stereotypes). At the same time gender norms can offer resources and enable strategies that allow individuals to adjust to a new condition generally considered unenviable.À partir d’une recherche sociologique portant sur la quête de travail des réfugiés dits « reconnus » en France et en Bulgarie, cet article se propose d’ouvrir le chantier de l’étude de la dimension genrée de leur rapport au travail. Les femmes et les hommes réfugiés devenus ouvriers vivent généralement cette nouvelle condition comme un déclassement social et professionnel, sous le mode de la perte de statut et de la fragilisation identitaire, ce qui amplifie l’expérience, propre à l’exil, des ruptures avec le monde habituel. Nous examinons comment ces ruptures peuvent s’accompagner de différents types de transformation de l’identification genrée (de la déstabilisation au renforcement des stéréotypes « virils » ou « féminins »), et comment les normes de genre peuvent offrir différentes ressources, et rendre possibles différentes stratégies, pour faire avec une nouvelle condition généralement considérée comme peu enviable

Ouvrier malgré soi : réfugié-e-s « reconnu-e-s » en France et en Bulgarie (début xxie siècle)

À partir d’une recherche sociologique portant sur la quête de travail des réfugiés dits « reconnus » en France et en Bulgarie, cet article se propose d’ouvrir le chantier de l’étude de la dimension genrée de leur rapport au travail. Les femmes et les hommes réfugiés devenus ouvriers vivent généralement cette nouvelle condition comme un déclassement social et professionnel, sous le mode de la perte de statut et de la fragilisation identitaire, ce qui amplifie l’expérience, propre à l’exil, des ruptures avec le monde habituel. Nous examinons comment ces ruptures peuvent s’accompagner de différents types de transformation de l’identification genrée (de la déstabilisation au renforcement des stéréotypes « virils » ou « féminins »), et comment les normes de genre peuvent offrir différentes ressources, et rendre possibles différentes stratégies, pour faire avec une nouvelle condition généralement considérée comme peu enviable.Drawing on a sociological study concerning “recognized” refugees in France and Bulgaria and their search for work, this article aims at opening a research field about the gender dimension of their relationship to work. The refugees who become workers generally experience this transformation as a loss of social and professional status that destabilizes their identity and amplifies the rupture with their habitual world that exile entails. The paper shows that these experiences of loss coincide with transformation in gender identifications (either destabilization or strengthening of “virile” or “feminine” stereotypes). At the same time gender norms can offer resources and enable strategies that allow individuals to adjust to a new condition generally considered unenviable

Control of drop shape transformations in cooled emulsions.

The general mechanisms of structure and form generation are the keys to understanding the fundamental processes of morphogenesis in living and non-living systems. In our recent study (Denkov et al., Nature 528 (2015) 392) we showed that micrometer sized n-alkane drops, dispersed in aqueous surfactant solutions, can break symmetry upon cooling and "self-shape" into a series of geometric shapes with complex internal structure. This phenomenon is important in two contexts, as it provides: (a) new, highly efficient bottom-up approach for producing particles with complex shapes, and (b) remarkably simple system, from the viewpoint of its chemical composition, which exhibits the basic processes of structure and shape transformations, reminiscent of morphogenesis events in living organisms. In the current study, we show for the first time that drops of other chemical substances, such as long-chain alcohols, triglycerides, alkyl cyclohexanes, and linear alkenes, can also evolve spontaneously into similar non-spherical shapes. We demonstrate that the main factors which control the drop "self-shaping", are the surfactant type and chain length, cooling rate, and initial drop size. The studied surfactants are classified into four distinct groups, with respect to their effect on the "self-shaping" phenomenon. Coherent explanations of the main experimental trends are proposed. The obtained results open new prospects for fundamental and applied research in several fields, as they demonstrate that: (1) very simple chemical systems may show complex structure and shape shifts, similar to those observed in living organisms; (2) the molecular self-assembly in frustrated confinement may result in complex events, governed by the laws of elasto-capillarity and tensegrity; (3) the surfactant type and cooling rate could be used to obtain micro-particles with desired shapes and aspect ratios; and (4) the systems studied serve as a powerful toolbox to investigate systematically these phenomena.This work was funded by the European Research Council (ERC) grant to Stoyan Smoukov, EMATTER (# 280078). The study falls under the umbrella of European networks COST MP 1106 and 1305.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.cis.2016.06.00

Editorial: The Condition of Refugee: Subjective Experiences and Collective Mobilisations

On Wednesday 8 January 2014, a tent surrounded by banners with various slogans was set up in front of the main entrance of the Cypriot Ministry of the Interior in Nicosia (see Photograph 1). Three people who had been recognised as refugees in Cyprus for almost ten years had been on hunger strike for several weeks; they were asking the authorities to grant them rights similar to those of Cypriots, to take action against the discrimination they face and in favour of the right to naturalisation...