Hormonal effects on expression of osmoregulatory genes in the gill of Japanese medaka (Oryzias latipes)

Japanese medaka (Oryzias latipes) are euryhaline teleost and evolved divergently from the well-studied model organism zebrafish (Danio rerio). Claudins (cldns) are tight junction proteins known to regulate the permeability of the paracellular space, but little is known about the influence of the endocrine system on their regulation. In this study, in vitro gill culture model was used to test the effect of three osmoregulatory hormones (cortisol, growth hormone, and prolactin) on eight cldns previously identified in the gills of medaka. The stress hormone cortisol generally up-regulated the genes studied from 1.2- to 5-fold at the exceptions of cldn-28a and -28b. Growth hormone had little effect and only increased the transcription of cldn-10f 2.5-fold, while prolactin up-regulated the expression of cldn-28b, -10c, and -10f, to 2-, 2.5-, and 2-fold respectively. The results support the hypothesis that cldns-27a, -28a, -28b, and -30c are barrier-forming cldns, with -28b being induced by FW conditions. Further experiments need to be performed before the hormonal regulation of cldn-10 isoforms can be fully understood. The in vitro model shown here is a useful tool to resolve endocrine control of gill proteins involved in osmoregulation. Further investigation of the possible interactions of cortisol and prolactin or growth hormone would improve the understanding of claudin regulation by hormones

Thick Target Yield of Th-229 via Low Energy Proton Bombardment of Th-232

Actinium-225 is one of the more effective radioisotopes used in alpha radioimmunotherapy. Due to its ten-day half-life, it is more efficient to create its precursor, 229Th [Thorium-229] (t1/2[half-life] = 7932 ± 55 years). In this work, 229Th was produced via 40 MeV [Mega electron Volts] proton bombardment of a thick 232Th [Thorium-232] target. The irradiation took place at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Lab (ORNL). The target, consisting of 23 stacked natural thorium foils (137 mg/cm2 [milligrams per square centimeter] each), was irradiated with 50 nA [nanoamps] of protons from HRIBF’s 25 MV [Mega Volt] tandem electrostatic accelerator for approximately 143 discontinuous hours. After 215 days post bombardment, allowing for the decay of short-lived protactinium and actinium isotopes and fission products, the target was chemically purified by a series of ion chromatography techniques. Thorium-229 was measured directly by γ-ray [gamma-ray] spectroscopy immediately after separation of the thorium fraction from the decay daughters of 228Th [Thorium-228] (t1/2 = 1.9 years) and long long-lived fission products. The effective thick target cross section of 229Th is 205 ± 18 mb [millibarns] at a proton energy of 26.1 MeV. Variation of the effective cross-section as a function of proton energy is also reported

Hierarchically Structured Photoelectrodes via Atomic Layer Deposition

In the search for a sustainable method to meet increasing energy needs, solar energy emerges as an underutilized, plentiful resource. Solar intermittency and requirements for transportation necessitate storing solar energy in the form of chemical bonds via artificial photosynthesis. Photoelectrochemical (PEC) water splitting generates hydrogen fuel from solar energy and water. A semiconducting material that successfully meets the complex requirements for building an industrially scalable PEC device has yet to emerge. This is leading to a reevaluation of materials previously overlooked within PEC research, mainly materials with limitations such as minimal charge carrier mobility and propensity to corrosion under illumination in aqueous environments. Cupric oxide (CuO) is one such candidate semiconductor, energetically suitable as a photocathode for PEC water splitting, and possesses both limitations mentioned above. Hierarchical three-dimensional structuring can circumvent the charge mobility limitations of CuO while maintaining its ability to absorb maximal incident solar illumination. Our proposed method of hierarchical structuring is coating nanometer-thick layers of CuO across a three-dimensional conductive scaffold of silica spheres, which maintains the path length of illumination through the semiconductor. Atomic Layer Deposition (ALD) can be used throughout construction of a PEC device based on this scaffold. In this work, the transparent conducting oxide (TCO) Al:ZnO (AZO) deposited using ALD is proposed as a conductive layer in hierarchical structuring of a PEC device. AZO is soluble in the extreme pH environments often present in current PEC water splitting research. An ultra-thin film of ALD-TiO2 is evaluated as a protection layer for AZO from chemical dissolution. This protection layer work is further applied to intervening in CuO photocorrosion. Additionally, we studied the impact the work function of a back contact in the PEC performance of protected CuO electrodes. We conclude with a discussion on the viability of CuO as a material for three-dimensional structuring in the proposed scaffold

A Long-Term Variability Study of Dying Low and Intermediate Mass Stars

We are studying the long-term light variation of dying stars (similar to the sun). These stars pulsate, causing them to vary in light. Our purpose is to better understand the internal structure of these objects though light curve and period analysis. These dying stars are in the proto-planetary nebula (PPN) phase, which lasts only a few thousand years between the red giant phase and the planetary nebula phase. First discovered with the Infrared Astronomical Satellite Survey in 1983, PPN emit strongly in the region, but the central stars of PPN can be studied in visible light. This summer we have observed 20 nights from the Valparaiso University Observatory gathering data for 26 stars. We also have data from collaborators using the SARA-North and SARA-South telescopes located at Kitt Peak, Arizona and Cerro Tololo, Chile, respectively. Our project has two main parts: (1) to continue the long-term observations of PPNs, which started in 1994, and (2) to combine the data from several CCD cameras to enlarge the sample and to better determine the light curves of PPN. We are analyzing a subset of 12 PPN to determine their pulsation periods and amplitudes in order to understand their long-term variability. About the authors: Allyse (Allie) Appel is currently a standing junior as a physics major. Her long-term goal is to go to graduate school, possibly receiving a PhD in Particle Physics or Astrophysics as well as to participate in research for the United States. Justin Reed is currently a sophomore physics major, unsure of future career plans. Both students are first year astronomy research students working with Dr. Bruce Hrivnak

An Examination of Configurations for Using Infrared to Measure Boundary Layer Transition

Infrared transition location estimates can be fast and useful measurements in wind tunnel and flight tests. Because turbulent boundary layers have a much higher rate of convective heat transfer than laminar boundary layers, a difference in surface temperature can be observed between turbulent and laminar regions of an airfoil at a different temperature than the free stream air temperature. Various implementations of this technique are examined in a wind tunnel. These include using a heat lamp as an external source and circulating fluid inside of the airfoil. Furthermore, ABS plastic and aluminum airfoils are tested with and without coatings such as black paint and surface wraps. The results show that thermal conduction within the model and surface reflections are the driving issues in designing an IR system for detecting transition. Aluminum has a high thermal diffusivity so is a poor choice for this method. However, its performance can be improved using an insulating layer. Internal fluid circulation was far more successful than the heat lamp because it eliminates the reflected IR due to the heat lamp. However, using smooth surface wraps can mitigate reflection issues caused by the heat lamps by reducing the scatter within the reflection, producing an IR image with fewer contaminating reflections

Session 4: James Merrill: Life and Archive

2:45 p.m. — Session 4: James Merrill: Life and Archive An introduction to James Merrill resources in Washington University Special Collections. See http://omeka.wustl.edu/omeka/exhibits/show/merrill-life-archiv