Structural Changes to Supported Water Nanoislands Induced by Kosmotropic Ions

Copyright © 2019 American Chemical Society. We report the influence of lithium ions on binding and structure of water nanoislands on Au(111) by temperature-programmed desorption and variable-temperature scanning tunneling microscopy. Water coverages between a fraction and full bilayer and two lithium coverages (<0.15% ML) are explored. Lithium enhances selectively the binding of some of the water molecules on precovered Au(111) as compared to water on pristine Au(111), which is revealed by an increase of the water desorption temperature by approx. 10 K. Surprisingly, the effect of lithium on the structure of water is much more extended than expected from these desorption experiments. A small amount of lithium changes the structure of water nanoislands drastically compared to those on pristine Au(111). On pristine Au(111), water ice grows in the form of crystalline islands that are two or three bilayers high. On Li precovered Au(111), the islands are more corrugated, at a 5 times broader apparent height distribution and much smaller, at a 4 times smaller area distribution. These changes reflect the influence of lithium as a structure maker, or kosmotrope, on water. Our study provides unprecedented real-space information of the influence of a kosmotrope on the water structure at the nanoscale. We utilize its kosmotropic behavior to provide real-space images of desorption.

An Investigation into the Hydration and Growth of Ice Layers on Metal Surfaces using Low Temperature Scanning Tunnelling Microscopy.

This thesis discusses the surface wetting of close-packed, open-faced and stepped metal surfaces and the variation in structures that form in this interfacial layer. It takes into account how specific sites can provide preferential binding, how the reactivity of different metals can have an effect on the structures which form and whether this influences dissociation. It also deliberates factors that help make a good ice nucleating agent and whether a surface can act as a template to grow an ordered multilayer film. Tackling a variety of different surface characteristics, the discussions in this thesis give a good overview of the field, but also the on-going issues and difficulties which still need to be addressed and hopefully overcome in the future

Strain Relief during Ice Growth on a Hexagonal Template.

Heterogeneous ice nucleation at solid surfaces impacts many areas of science, from environmental processes, such as precipitation, to microbiological systems and food processing, but the microscopic mechanisms underpinning nucleation remain unclear. Discussion of ice growth has often focused around the role of the surface in templating the structure of water, forcing the first layer to adopt the registry of the underlying substrate rather than that of ice. To grow a thick ice film, water in the first few ice layers must accommodate this strain, but understanding how this occurs requires detailed molecular-scale information that is lacking. Here we combine scanning tunneling microscopy, low-energy electron diffraction, and work-function measurements with electronic structure calculations to investigate the initial stages of ice growth on a Pt alloy surface, having a lattice spacing 6% larger than ice. Although the first layer of water forms a strictly commensurate hexagonal network, this behavior does not extend to the second layer. Instead, water forms a 2D structure containing extended defect rows made from face-sharing pentamer and octamer rings. The defect rows allow the majority of second-layer water to remain commensurate with the solid surface while compensating lateral strain by increasing the water density close to that of an ice surface. The observation of octamer-pentamer rows in ice films formed on several surfaces suggests that the octamer-pentamer defect motif acts as a flexible strain relief mechanism in thin ice films, providing a mechanism that is not available during the growth of strained films in other materials, such as semiconductors

Racism and Sexism, Together, in Counselling: Three Women of Colour Tell Their Stories

Ten women of colour were interviewed for qualitative research about their experiences as clients in mental health systems. Of these, three stories are used here as examples. Preceding the stories, the terms "racism," "sexism," and "mental health systems" are defined. The dilemma of a white researcher doing research on women of colour presents moral, ethical, and political concerns. The ten women's paradigms of racism and sexism are summarized. The stories and the impact that the experiences had on the women are discussed. Suggestions for counselling research, theory, and practice include addressing racism within ourselves and with women of colour clients, and making space for women of colour in the centre of counseling work.Dix femmes de couleur ont été interviewées pour une recherche qualitative concernant leurs expériences comme clientes dans les systèmes de santé mentale. De celles-ci, trois histoires sont utilisées comme exemples. Précédent ces histoires, les termes "racisme", "sexisme" et "systèmes de santé mentale" sont définis. Ledilemme d'un chercheur blanc faisant de la recherche auprès de femmes de couleur soulève des problèmes moraux, éthiques et politiques. Les paradigmes sur le racisme et le sexisme des dix femmes sont résumés. Les histoires ainsi que l'impact de leurs expériences par rapport à elles-mêmes sont discutés. Des suggestions pour la recherche, la théorie et la pratique en counseling incluent le racisme vécu, perçu par le thérapeute à l'intérieur de lui-même et vis-à-vis les clientes de couleur, et de créer une place pour les femmes de couleur dans le milieu du counseling

Constitutional 11p15 abnormalities, including heritable imprinting center mutations, cause nonsyndromic Wilms tumor

Constitutional abnormalities at the imprinted 11p15 growth regulatory region cause syndromes characterized by disordered growth, some of which include a risk of Wilms tumor(1-3). We explored their possible contribution to nonsyndromic Wilms tumor and identified constitutional 11p15 abnormalities in genomic lymphocyte DNA from 13 of 437 individuals (3%) with sporadic Wilms tumor without features of growth disorders, including 12% of bilateral cases (P = 0.001) and in one familial Wilms tumor pedigree. No abnormality was detected in 220 controls (P = 0.006). Abnormalities identified included H19 DMR epimutations, uniparental disomy 11p15 and H19 DMR imprinting center mutations (one microinsertion and one microdeletion), thus identifying microinsertion as a new class of imprinting center mutation. Our data identify constitutional 11p15 defects as one of the most common known causes of Wilms tumor, provide mechanistic insights into imprinting disruption and reveal clinically important epigenotype-phenotype associations. The impact on clinical management dictates that constitutional 11p15 analysis should be considered in all individuals with Wilms tumor