scholarly journals The Contrasting Role of Water and Acid Within Organic Phase Amphiphile Aggregation

2021 ◽  
Author(s):  
Biswajit Sadhu ◽  
Aurora E. Clark
Keyword(s):  
Self Assembly ◽  
Dynamics Simulation ◽  
Test Bed ◽  
Network Analyses ◽  
Liquid Liquid Extraction ◽  
Polar Media ◽  
Polar Solutes ◽  
Local Aggregation ◽  
The Individual

Hypothesis: Amphiphile self-assembly in non-polar media is often enhanced by polar co-solutes, as observed upon amphiphile mediated transport of water and acid into organic solution. Such co-extraction precludes understanding the individual roles of polar solutes upon self-assembly. Using this liquid-liquid extraction (LLE) system as a test-bed, we hypothesize that co-solute competition and hydrogen bond (HB) characteristics cause different size/shape distributions of assembled amphiphiles and alter self-assembly mechanisms in non-polar solvents. Experiments: Concentration dependent classical molecular dynamics simulation and intermolecular network analyses identified the correlating relationships between HB properties of H2O and HNO3 upon the aggregation of N,N,N,N-tetraoctyl-3-oxapentanediamide (TODGA), a prevalent LLE amphiphile extractant. Findings: Concentration dependent competition of hydrogen bonding fundamentally impacts amphiphile self-assembly in non-polar media. H2O bridges TODGA and enhances self-assembly, however as [H2O]org increases, preferential self-solvation leads to large (H2O)n clusters that cause TODGA clusters to sorb to the (H2O)n periphery and form extended aggregation. HNO3 restricts the (H2O)n size by disrupting the HB network. At large [H2O]org, HNO3 modulates TODGA self-assembly from extended to local aggregation. We attribute prior experimental observations to the role of water rather than co-extracted HNO3, thus providing valuable new insight into the means by which extractant aggregation can be tuned.

scholarly journals Self-Assembly and Magnetic Order of Bi-Molecular 2D Spin Lattices of M(II,III) Phthalocyanines on Au(111)

2021 ◽  
Vol 7 (8) ◽  
pp. 119
Author(s):  
Miloš Baljozović ◽  
Xunshan Liu ◽  
Olha Popova ◽  
Jan Girovsky ◽  
Jan Nowakowski ◽  
...  
Keyword(s):  
Self Assembly ◽  
Present Report ◽  
Single Layer ◽  
Physico Chemical ◽  
Electronic Surface State ◽  
The Individual ◽  
Low Dimensional ◽  
Low Dimensional Materials ◽  
Electronic Surface

Single layer low-dimensional materials are presently of emerging interest, including in the context of magnetism. In the present report, on-surface supramolecular architecturing was further developed and employed to create surface supported two-dimensional binary spin arrays on atomically clean non-magnetic Au(111). By chemical programming of the modules, different checkerboards were produced combining phthalocyanines containing metals of different oxidation and spin states, diamagnetic zinc, and a metal-free ‘spacer’. In an in-depth, spectro-microscopy and theoretical account, we correlate the structure and the magnetic properties of these tunable systems and discuss the emergence of 2D Kondo magnetism from the spin-bearing components and via the physico-chemical bonding to the underlying substrate. The contributions of the individual elements, as well as the role of the electronic surface state in the bottom substrate, are discussed, also looking towards further in-depth investigations.

scholarly journals The Contrasting Role of Water and Acid Within Organic Phase Amphiphile Aggregation

2021 ◽  
Author(s):  
Biswajit Sadhu ◽  
Aurora E. Clark
Keyword(s):  
Self Assembly ◽  
Metal Ion ◽  
Water Clusters ◽  
Preferential Solvation ◽  
Water Concentration ◽  
The Self ◽  
Acid Extraction ◽  
Large Water ◽  
The Individual

The self-assembly of amphiphiles is often modified by the presence of co-solutes and significant study has examined this behavior in aqueous systems. Much less is known about the role of polar co-solutes upon amphiphile aggregation within non-polar media, however such conditions are relevant to a variety of industrial processes - not the least of which are separations systems like those found in liquid-liquid extraction (LLE). Therein, surface active amphiphiles extract water, acid, and other solutes of interest. Intriguing increases to amphiphile aggregates have been experimentally observed upon water and acid extraction, however a myriad of competitive intermolecular interactions have thus far prevented a fundamental understanding of the individual and dual role of these solutes upon amphiphile self-assembly. Toward this end, this work employs classical molecular dynamics and graph theory analyses to deconstruct the individual affects of water and nitric acid upon the self-assembly of N,N,N',N'-tetraoctyl-3-oxapentanediamide (TODGA), a prevalent amphiphile extractant used in metal ion separations. In the absence of acid, and at low water concentration, H2O is found to promote local dimer and trimer formation of TODGA, however as [H2O]org increases, the preferential solvation of water with itself causes the formation of large water clusters that serve to link large TODGA clusters on the periphery (causing extended aggregation). Addition of HNO3 to the humid solutions disrupts the water hydrogen bond network and inhibits the formation of large water clusters - thus preventing extended aggregation behavior. We rationalize the prior experimental observations as being attributed primarily to the role of water in the self-assembly of TODGA rather than co-extracted HNO3, thus providing valuable new insight into the means by which extractant aggregation can be tuned within LLE processes. In addition, this work differentiates the role of polar solutes upon amphiphile self-assembly via their individual hydrogen bonding capabilities and competitive interactions that disrupt preferred solvation environments.

Coupling of Geometric and Material Stiffening Mechanisms in Origami Design

2016 ◽  
Author(s):  
Michael Kuhn ◽  
Kazuko Fuchi ◽  
Giorgio Bazzan ◽  
Michael J. Durstock ◽  
James J. Joo ◽  
...  
Keyword(s):  
Self Assembly ◽  
Mechanical Response ◽  
Computational Study ◽  
Shape Change ◽  
Spatial Patterning ◽  
Material Stiffness ◽  
Paper Folding ◽  
Geometric Stiffening ◽  
The Individual

Origami, the ancient art of paper folding, has recently garnered attention from the scientific community for its capacity for unique 2D – 3D shape change and programmable mechanical properties. Application areas of such properties include packaging, self-assembly, shock absorption and deployable structures. Recent studies have highlighted the role of the folded geometry to regulate the mechanical response of the origami structures, such as the increased compression stiffness of origami tubes or the tunable in-plane stiffness through select inversion of bi-stable fold vertices. In addition to geometric re-enforcement, the mechanical response of an origami structure can also be programmed through spatial patterning of the individual fold line stiffnesses. However, the coupling between the geometric and material stiffening design spaces for origami structures is poorly understood and design rules are needed to guide the use of material stiffening to enhance or mitigate a geometric stiffening effect. In this computational study, a modal analysis of a corrugated fold with varying degrees of pre-fold and different sets of fold stiffness distributions is evaluated to highlight the interaction between geometric and material stiffness mechanisms.

scholarly journals Cross-talk between individual phenol soluble modulins in S. aureus biofilm formation

2020 ◽  
Author(s):  
Masihuz Zaman ◽  
Maria Andreasen
Keyword(s):  
Self Assembly ◽  
Biofilm Formation ◽  
Opportunistic Pathogen ◽  
Spectroscopic Techniques ◽  
Secondary Nucleation ◽  
Primary Nucleation ◽  
Functional Amyloids ◽  
The Individual ◽  
High Degree

ABSTRACTThe infective ability of the opportunistic pathogen Staphylococcus aureus is associated with biofilm mediated resistance to host immune response and even disinfectants and indeed S. aureus is recognized as the most frequent cause of biofilm associated infections. Phenol-soluble modulin (PSM) peptides serve various roles in pathogenicity while also comprising the structural scaffold of S. aureus biofilms through self-assembly into functional amyloids, but the role of the individual PSMs during biofilm formation remains poorly understood and the molecular pathways of PSM self-assembly have proved challenging to identify. Here, we show a high degree of cooperation between individual PSMs during the formation of functional amyloids in biofilm formation. The fast aggregating PSMα3 initiates the aggregation by forming unstable aggregates capable of seeding the formation of aggregates by other PSM peptides into the formation of stable amyloid structures. Using chemical kinetics along with spectroscopic techniques we dissect the molecular mechanism of aggregation of the individual peptides to show that PSMα1, PSMα3 and PSMβ1 display secondary nucleation whereas βPSM2 aggregates through primary nucleation and elongation. Our findings suggest that the various PSMs have evolved to ensure fast and efficient biofilm formation through cooperation between individual peptides.

School Success and School Engagement of Immigrant Children and Adolescents

2013 ◽  
Vol 18 (2) ◽  
pp. 126-135 ◽  
Author(s):  
Frosso Motti-Stefanidi ◽  
Ann S. Masten
Keyword(s):  
Academic Achievement ◽  
Academic Success ◽  
Children And Adolescents ◽  
School Engagement ◽  
School Success ◽  
Immigrant Children ◽  
Integrative Model ◽  
High Stakes ◽  
The Individual

Academic achievement in immigrant children and adolescents is an indicator of current and future adaptive success. Since the future of immigrant youths is inextricably linked to that of the receiving society, the success of their trajectory through school becomes a high stakes issue both for the individual and society. The present article focuses on school success in immigrant children and adolescents, and the role of school engagement in accounting for individual and group differences in academic achievement from the perspective of a multilevel integrative model of immigrant youths’ adaptation ( Motti-Stefanidi, Berry, Chryssochoou, Sam, & Phinney, 2012 ). Drawing on this conceptual framework, school success is examined in developmental and acculturative context, taking into account multiple levels of analysis. Findings suggest that for both immigrant and nonimmigrant youths the relationship between school engagement and school success is bidirectional, each influencing over time the other. Evidence regarding potential moderating and mediating roles of school engagement for the academic success of immigrant youths also is evaluated.

Role of Transcriptional Read-Through in PRE Activity in Drosophila melanogaster

Acta Naturae ◽  
2016 ◽  
Vol 8 (2) ◽  
pp. 79-86 ◽  
Author(s):  
P. V. Elizar’ev ◽  
D. V. Lomaev ◽  
D. A. Chetverina ◽  
P. G. Georgiev ◽  
M. M. Erokhin
Keyword(s):  
Dna Sequences ◽  
Cell Types ◽  
Transcription Terminator ◽  
Response Elements ◽  
Polycomb Response Elements ◽  
The Individual ◽  
Multicellular Organisms ◽  
Different Cell Types ◽  
Main Factor

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesnt prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.

УКРАЇНОЗНАВЧИЙ ОСВІТНІЙ ЧИННИК В УМОВАХ СУЧАСНОЇ УКРАЇНСЬКОЇ МАСОВОЇ КУЛЬТУРИ

2019 ◽  
pp. 22-29
Author(s):  
Н. В. Фрадкіна
Keyword(s):  
Mass Culture ◽  
Personal Development ◽  
Negative Impact ◽  
Educational Process ◽  
Point Of View ◽  
Character Trait ◽  
Main Task ◽  
Leading Role ◽  
The Individual

The purpose and tasks of the work are to analyze the contemporary Ukrainian mass culture in terms of its value and humanistic components, as well as the importance of cultural studies and Ukrainian studies in educational disciplines for the formation of a holistic worldview of modern youth.Analysis of research and publications. Scientists repeatedly turned to the problems of the role of spirituality in the formation of society and its culture. This problem is highlighted in the publications by O. Losev, V. Lytvyn, D. Likhachev, S. Avierintsev, M. Zakovych, I. Stepanenko and E. Kostyshyn.Experts see the main negative impact of mass culture on the quality approach, which determines mass culture through the market, because mass culture, from our point of view, is everything that is sold and used in mass demand.One of the most interesting studies on this issue was the work by the representatives of Frankfurt School M. Horkheimer and T. Adorno «Dialectics of Enlightenment» (1947), devoted to a detailed analysis of mass culture. Propaganda at all socio-cultural levels in the form is similar in both totalitarian and democratic countries. It is connected, according to the authors, with the direction of European enlightenment. The tendency to unify people is a manifestation of the influence of mass culture, from cinema to pop. Mass culture is a phenomenon whose existence is associated with commerce (accumulation in any form – this is the main feature of education), in general, the fact that it exists in this form is related to the direction of the history of civilization.Modern mass culture, with its externally attractive and easily assimilated ideas and symbols, appealing to the trends of modern fashion, becomes a standard of prestigious consumption, does not require intense reflection, allows you to relax, distract, not teach, but entertains, preaches hedonism as the main spiritual value. And as a consequence, there are socio-cultural risks: an active rejection of other people, which leads to the formation of indifference; cruelty as a character trait; increase of violent and mercenary crime; increase in the number of alcohol and drug addicts; anti-patriotism; indifference to the values of the family and as a result of social orphanhood and prostitution.Conclusions, perspectives of research. Thus, we can conclude that modern Ukrainian education is predominantly formed by the values of mass culture. Namely, according to the «Dialectic» by Horkheimer and Adorno, «semi-enlightenment becomes an objective spirit» of our modern society.It is concluded that only high-quality education can create the opposite of the onset of mass culture and the destruction of spirituality in our society. It is proved that only by realizing the importance of cultivating disciplines in the educational process and the spiritual upbringing of the nation, through educational reforms, humanitarian knowledge will gradually return to student audiences.Formation of youth occurs under the influence of social environment, culture, education and self-education. The optimal combination of these factors determines both the process of socialization itself and how successful it will be. In this context, one can see the leading role of education and upbringing. It turns out that the main task of modern education is to spread its influence on the development of spiritual culture of the individual, which eventually becomes a solid foundation for the formation of the individual. Such a subject requires both philosophical and humanitarian approaches in further integrated interdisciplinary research, since the availability of such research will provide the theoretical foundation for truly modern educational and personal development.

MEDIA SOCIALIZATION OF PERSONALITY IN THE CONTEXT OF INMUTATION IN THE MASS MEDIA

2021 ◽  
pp. 104-109
Author(s):  
Chernysh O.O.
Keyword(s):  
Mass Media ◽  
Negative Impact ◽  
Effective Interaction ◽  
Individual Characteristics ◽  
Media Culture ◽  
Active Growth ◽  
Media Space ◽  
The Media ◽  
The Individual

The urgency of the researched problem is connected with the growing role of mass media in modern conditions leads to change of values and transformation of identity of the person. The active growth of the role of the media, their influence on the formation and development of personality leads to the concept of “media socialization” and immutation in the media. The aim of the study is to outline the possibilities of the process of media socialization in the context of immutation in the media. The methods of our research are: analysis of pedagogical, psychological, literature, synthesis, comparison, generalization. The article analyzes the views of domestic and foreign scientists on the problem of immutation in the media and the transformation of the information space. In the context of the mass nature of the immutation of society, the concept of “media socialization” becomes relevant, which is the basis for reducing the negative impact of the media on the individual.The author identifies the lack of a thorough study of the concept of “media socialization” in modern scientific thought. Thus, media socialization is associated with the transformation of traditional means of socialization, and is to assimilate and reproduce the social experience of mankind with the help of new media.The article analyzes the essence of the concepts “media space”, “mass media” and “immutation”. The influence of mass media on the formation and development of the modern personality is described in detail.The study concluded that it is necessary to form a media culture of the individual, to establish safe and effective interaction of young people with the modern media system, the formation of media awareness, media literacy and media competence in accordance with age and individual characteristics for successful media socialization. The role of state bodies in solving the problem of media socialization of the individual was also determined. It is determined that the process of formation of media culture in youth should take place at the level of traditional institutions of socialization of the individual.The author sees the prospect of further research in a detailed analysis and study of the potential of educational institutions as an institution and a means of counteracting the mass nature of the immutation of society.Key words: immutation, media socialization, mass media, media space, information.

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