Non-equilibrium induction of tin in germanium: towards direct bandgap Ge1−xSnx nanowires

The development of non-equilibrium group IV nanoscale alloys is critical to achieving new functionalities, such as the formation of a direct bandgap in a conventional indirect bandgap elemental semiconductor. Here, we describe the fabrication of uniform diameter, direct bandgap Ge1−xSnx alloy nanowires, with a Sn incorporation up to 9.2 at.%, far in excess of the equilibrium solubility of Sn in bulk Ge, through a conventional catalytic bottom-up growth paradigm using noble metal and metal alloy catalysts. Metal alloy catalysts permitted a greater inclusion of Sn in Ge nanowires compared with conventional Au catalysts, when used during vapour–liquid–solid growth. The addition of an annealing step close to the Ge-Sn eutectic temperature (230 °C) during cool-down, further facilitated the excessive dissolution of Sn in the nanowires. Sn was distributed throughout the Ge nanowire lattice with no metallic Sn segregation or precipitation at the surface or within the bulk of the nanowires. The non-equilibrium incorporation of Sn into the Ge nanowires can be understood in terms of a kinetic trapping model for impurity incorporation at the triple-phase boundary during growth

Relationship between the magnitude of intraocular pressure during an episode of acute elevation and retinal damage four weeks later in rats

PURPOSE: To determine relationship between the magnitude of intraocular pressure (IOP) during a fixed-duration episode of acute elevation and the loss of retinal function and structure 4 weeks later in rats. METHODS: Unilateral elevation of IOP (105 minutes) was achieved manometrically in adult Brown Norway rats (9 groups; n = 4 to 8 each, 10-100 mm Hg and sham control). Full-field ERGs were recorded simultaneously from treated and control eyes 4 weeks after IOP elevation. Scotopic ERG stimuli were white flashes (-6.04 to 2.72 log cd.s.m(-2)). Photopic ERGs were recorded (1.22 to 2.72 log cd.s.m(-2)) after 15 min of light adaptation (150 cd/m(2)). Relative amplitude (treated/control, %) of ERG components versus IOP was described with a cummulative normal function. Retinal ganglion cell (RGC) layer density was determined post mortem by histology. RESULTS: All ERG components failed to recover completely normal amplitudes by 4 weeks after the insult if IOP was 70 mmHg or greater during the episode. There was no ERG recovery at all if IOP was 100 mmHg. Outer retinal (photoreceptor) function demonstrated the least sensitivity to prior acute IOP elevation. ERG components reflecting inner retinal function were correlated with post mortem RGC layer density. CONCLUSIONS: Retinal function recovers after IOP normalization, such that it requires a level of acute IOP elevation approximately 10 mmHg higher to cause a pattern of permanent dysfunction similar to that observed during the acute event. There is a 'threshold' for permanent retinal functional loss in the rat at an IOP between 60 and 70 mmHg if sustained for 105 minutes or more

Porcine Ex Vivo intestinal segment model

This chapter describes the use of the porcine ex vivo intestinal segment model. This includes the advantages and disadvantages of the segment model and a detailed description of the isolation and culture as well as the applications of the porcine ex vivo intestinal segment model in practice. Compared to the Ussing chamber (Chap. 24) the porcine ex vivo small intestinal segment model is a relatively simple to use intestinal tissue model. The main difference being that the tissue segment is not mounted in a chamber, but is freely floating in a solution. Therefore the ex vivo intestinal segment model does not distinguish between the apical and basolateral side of the tissue. The intestinal segments can be obtained from various anatomical regions of the small intestine (e.g. duodenum, jejunum, ileum or even the colon) and the segments consist of various cell types (e.g. epithelial cells, paneth cells, goblet cells, enterochromaffin cells and enteroendocrine cells). The intestinal segment model has been shown to be a suitable tool to study compound and location specific effects on the release of gastrointestinal hormones and gastrointestinal metabolism of endocannabinoids and related compounds

Oestrogen receptors and breast cancer. are we prepared to move forward? A critical review

It is nearly 60 years since the identification of the oestrogen hormone receptor (ER) in breast cancer, a discovery that radically transformed the clinical management of the disease. Hormonal therapy with anti-oestrogens (Tamoxifen and Aromatase inhibitors) antagonise ER function and became the mainstay treatment until today. Around 70% of breast tumours are classified as oestrogen dependent, yet the mechanism of action of other hormones in breast cancer growth both independently and interacting with ER as well as their targeted therapies have yet to find a place in the clinic. In this article, I critically review the scientific literature for the period 1960-2016, examine the rise and persistence of the oestrogen hypothesis as well as the neglect of alternative hormonal explanations. By using Pierre Bourdieu’s concepts of the scientific field alongside feminist science scholars to explore the impact of gendered assumptions on science, the analysis provides insight into the dominant role of the oestrogen hypothesis and the struggles for legitimation of different alternative perspectives. I consider these alternative approaches as “internal” struggles for scientific authority, which are in turn, socially determined by “external” gender values that reinforce a binary arrangement of male/female bodies based on fixed molecular hormonal traits