Determination of Inconel-625 corrosion rate in NaKMg-Cl molten salt via linear sweep voltammetry

Concentrating solar power (CSP) systems focus light energy from the sun to generate heat. Heat transfer fluids (HTF) act as thermal energy storage in CSP systems. The HTF flows through the system in a containment material; molten salts have served as HTFs in CSP systems. As the molten salts move through the system, the containment material is subject to corrosion_Üîlessening the lifetime of the system. To create affordable CSP, various compositions of molten salts and containment materials have been tested. Via linear sweep voltammetry (LSV), the corrosion rate of Inconel-625 was studied. A NaKMg-Cl molten salt composition_Üî24.5-20.5-55 %wt NaCl-KCl-MgCl2_Üîwas utilized during experimentation. An extensive purification process was used to remove water from the salt prior to LSV; water in a MgCl2-based CSP system leads to the formation of HCl, increasing the corrosion rate of the containment material in use. Due to time constraints, the results of the study have not been collected. LSV test results are currently being extrapolated to calculate the corrosion rate of Inconel-625 in 24.5-20.5-55.0 wt% NaCl-KCl-MgCl2

Abundances in Stars from the Red Giant Branch Tip to the Near Main Sequence in M71: II. Iron Abundance

We present [Ffe/H] abundance results that involve a sample of stars with a wide range in luminosity from luminous giants to stars near the turnoff in a globular cluster. Our sample of 25 stars in M71 includes 10 giant stars more luminous than the RHB, 3 horizontal branch stars, 9 giant stars less luminous than the RHB, and 3 stars near the turnoff. We analyzed both Fe I and Fe II lines in high dispersion spectra observed with HIRES at the W. M. Keck Observatory. We find that the [Fe/H] abundances from both Fe I and Fe II lines agree with each other and with earlier determinations. Also the [Fe/H] obtained from Fe I and Fe II lines is constant within the rather small uncertainties for this group of stars over the full range in Teff and luminosity, suggesting that NLTE effects are negligible in our iron abundance determination. In this globular cluster, there is no difference among the mean [Fe/H] of giant stars located at or above the RHB, RHB stars, giant stars located below the RHB and stars near the turnoff.Comment: Minor changes to conform to version accepted for publication, with several new figures (Paper 2 of a pair

Stellar Archaeology: a Keck Pilot Program on Extremely Metal- Poor Stars From the Hamburg/ESO Survey. III. The Lead (Pb) Star HE 0024-2523

We present a detailed abundance analysis, including spectral syntheses, of a very metal-poor ([Fe/H]= -2.7), peculiar main sequence star, HE0024-2523 detected during the course of the Keck Pilot Program. Radial velocities of this star were obtained during four different observing runs over a time span of 1.1 years, and demonstrate that it is clearly a short period spectroscopic binary. An orbital solution was obtained, and orbital parameters were determined with high precision. The rotational velocity was also measured (vsin i=9.7$\pm$1.5 kms); rotation appears likely to be synchronous with the orbit. The abundance analysis and spectral syntheses indicate that the object is a CH star characterized by extreme s-process enrichment, likely due to mass accretion from an evolved companion which has now probably become a white dwarf. The lead (Pb) abundance of HE0024-2523 is very high, the same as that of the recently discovered lead-rich metal-poor star CS 29526-110, [Pb/Fe]=+3.3. The abundance ratio of the heavy-s to light-s elements, as characterized by Pb and Ba, [Pb/Ba]=+1.9, is the highest yet found for any metal-poor star, and is about 0.7 dex higher than that of CS29526-110. On the basis of the measured isotopic ratio of carbon (12C/13C about 6) we argue that the mass donor must have had an original mass of at least 3 Msun. The unusually short period of this CH star suggests that it underwent a past common-envelope phase with its evolved companion. Our results are compared to the latest available models for AGB yields and s-process nucleosynthesis. We also discuss the possible connection between HE0024-2523 the lithium depletion of halo stars, and halo blue straggler formation.Comment: 55 pages, 17 color figures included; Accepted for publication in the February 2003 issue of the Astronomical Journa

Abundances in Stars from the Red Giant Branch Tip to Near the Main Sequence Turn Off in M5

We present the iron abundance and abundance ratios for 18 elements with respect to Fe in a sample of stars with a wide range in luminosity from luminous giants to stars near the turnoff in the globular cluster M5. The analyzed spectra, obtained with HIRES at the Keck Observatory, are of high dispersion (R=35,000). We find that the neutron capture, the iron peak and the alpha-element abundance ratios show no trend with Teff, and low scatter around the mean between the top of the RGB and near the main sequence turnoff To within the precision of the measurements (~0.1 dex), gravitationally induced heavy element diffusion does not appear to be present among the stars near the main sequence turnoff studied here. Our work and other recent studies suggest that heavy element diffusion is inhibited in the surface layers of metal poor stars. Differences in the Na abundance from star to star which extend to the main sequence turnoff are detected in our sample in M5. The anti-correlation between O and Na abundances, observed in other metal poor globular clusters, is not detected in our sample, but it may be hidden among stars with only upper limits for their O abundances. Overall the abundance ratios of M5 appear very similar to those of M71, with the possible exception of the neutron capture element Ba, where we argue that the apparent difference may be due to difficulties in the analysis. As in M71, the alpha-elements Mg, Ca, Si and Ti are overabundant relative to Fe. The results of our abundance analysis of 25 stars in M5 provide further evidence of abundance variations among specific light elements at unexpectedly low luminosities, which cannot be explained by our current understanding of stellar evolution.Comment: 56 pages, 14 figures, AJ in press (Jan 2003

Fungal entomopathogens: new insights on their ecology

An important mechanism for insect pest control should be the use of fungal entomopathogens. Even though these organisms have been studied for more than 100 y, their effective use in the field remains elusive. Recently, however, it has been discovered that many of these entomopathogenic fungi play additional roles in nature. They are endophytes, antagonists of plant pathogens, associates with the rhizosphere, and possibly even plant growth promoting agents. These findings indicate that the ecological role of these fungi in the environment is not fully understood and limits our ability to employ them successfully for pest management. In this paper, we review the recently discovered roles played by many entomopathogenic fungi and propose new research strategies focused on alternate uses for these fungi. It seems likely that these agents can be used in multiple roles in protecting plants from pests and diseases and at the same time promoting plant growth

2020 Collage Concert

An exciting highlight each season, Collage is the signature production of the School of Music and a major fundraising event for supporting scholarships for music students. This special performance features over 200 student and faculty performers and includes jazz, orchestra, choir, band, percussion, and opera selections for soloists, chamber groups, and ensembles. Special lighting effects and stage design combine with the diverse and exciting program presented as rapid-fire, flowing vignettes to create a truly unique performance.https://digitalcommons.kennesaw.edu/musicprograms/2295/thumbnail.jp

Measuring Biodiversity and Extinction – Present and Past

How biodiversity is changing in our time represents a major concern for all organismal biologists. Anthropogenic changes to our planet are decreasing species diversity through the negative effects of pollution, habitat destruction, direct extirpation of species, and climate change. But major biotic changes – including those that have both increased and decreased species diversity – have happened before in Earth’s history. Biodiversity dynamics in past eras provide important context to understand ecological responses to current environmental change. The work of assessing biodiversity is woven into ecology, environmental science, conservation, paleontology, phylogenetics, evolutionary and developmental biology, and many other disciplines; yet, the absolute foundation of how we measure species diversity depends on taxonomy and systematics. The aspiration of this symposium, and complementary contributed talks, was to promote better understanding of our common goals and encourage future interdisciplinary discussion of biodiversity dynamics. The contributions in this collection of papers bring together a diverse group of speakers to confront several important themes. How can biologists best respond to the urgent need to identify and conserve diversity? How can we better communicate the nature of species across scientific disciplines? Where are the major gaps in knowledge about the diversity of living animal and plant groups, and what are the implications for understanding potential diversity loss? How can we effectively use the fossil record of past diversity and extinction to understand current biodiversity loss

Supervising the Supervisors—Procedural Training and Supervision in Internal Medicine Residency

At teaching hospitals, bedside procedures (paracentesis, thoracentesis, lumbar puncture, arthrocentesis and central venous catheter insertion) are performed by junior residents and supervised by senior peers. Residents’ perceptions about supervision or how often peer supervision produces unsafe clinical situations are unknown. To examine the experience and practice patterns of residents performing bedside procedures. Cross-sectional e-mail survey of 653 internal medicine (IM) residents at seven California teaching hospitals. Surveys asked questions in three areas: (1) resident experience performing procedures: numbers of procedures performed and whether they received other (e.g., simulator) training; (2) resident comfort performing and supervising procedures; (3) resident reports of their current level of supervision doing procedures, experience with complications as well as perceptions of factors that may have contributed to complications. Three hundred sixty-seven (56%) of the residents responded. Most PGY1 residents had performed fewer than five of any of the procedures, but most PGY-3 residents had performed at least ten by the end of their training. Resident comfort for each procedure increased with the number of procedures performed (p < 0.001). Although residents reported that peer supervision happened often, they also reported high rates of supervising a procedure before feeling comfortable with proper technique. The majority of residents (64%) reported at least one complication and did not feel supervision would have prevented complications, even though many reported complications represented technique- or preparation-related problems. Residents report low levels of comfort and experience with procedures, and frequently report supervising prior to feeling comfortable. Our findings suggest a need to examine best practices for procedural supervision of trainees

Stellar Archaeology: a Keck Pilot Program on Extremely Metal-Poor Stars from the Hamburg/ESO Survey. II. Abundance Analysis

We present a detailed abundance analysis of 8 stars selected as extremely metal poor candidates from the Hamburg/ESO Survey (HES). For comparison, we have also analysed 3 extremely metal-poor candidates from the HK survey, and 3 additional bright metal-poor stars. With this work, we have doubled the number of extremely metal-poor stars ([Fe/H]$\le 3.0$) with high-precision abundance analyses. Our sample of extremely metal-poor candidates from the HES contains 3 stars with [Fe/H] $\le -3.0$, 3 more with [Fe/H]$\le -2.8$, and 2 stars that are only slightly more metal rich. Thus, the chain of procedures that led to the selection of these stars from the HES successfully provides a high fraction of extremely metal-poor stars. We verify that our stellar parameters, derived in Paper I, lead to acceptable ionization and excitation balances for Fe, ruling out substantial non-LTE effects in Fe. For the $\alpha-$elements Mg, Si, Ca, Ti, the light element Al, the iron-peak elements Sc, Cr, Mn, and the neutron capture elements Sr and Ba, we find trends in abundance ratios [X/Fe] similar to those found by previous studies. However,the scatter in most of these ratios, even at [Fe/H]$\le -3.0$ dex, is surprisingly small. Only Sr and Ba show scatter larger than the expected errors. Future work (the 0Z project) will provide much stronger constraints on the scatter (or lack thereof) in abundances for a greater number of stars. We discuss the implications of these results for the early chemical evolution of the Galaxy, including such issues as the number of contributing SN, and the sizes of typical fragments in which they were born. In addition, we have identified a very metal poor star that appears to be the result of the s-process chain, operating in a very metal-poor environment, with extremely enhanced C, Ba, and Pb, and somewhat enhanced Sr.Comment: 36 pages, 9 tables, 14 figures included; accepted for publication in the July 2002 issue of The Astronomical Journa