The 10 kW power electronics for hydrogen arcjets

A combination of emerging mission considerations such as 'launch on schedule', resource limitations, and the development of higher power spacecraft busses has resulted in renewed interest in high power hydrogen arcjet systems with specific impulses greater than 1000 s for Earth-space orbit transfer and maneuver applications. Solar electric propulsion systems with about 10 kW of power appear to offer payload benefits at acceptable trip times. This work outlines the design and development of 10 kW hydrogen arcjet power electronics and results of arcjet integration testing. The power electronics incorporated a full bridge switching topology similar to that employed in state of the art 5 kW power electronics, and the output filter included an output current averaging inductor with an integral pulse generation winding for arcjet ignition. Phase shifted, pulse width modulation with current mode control was used to regulate the current delivered to arcjet, and a low inductance power stage minimized switching transients. Hybrid power Metal Oxide Semiconductor Field Effect Transistors were used to minimize conduction losses. Switching losses were minimized using a fast response, optically isolated, totem-pole gate drive circuit. The input bus voltage for the unit was 150 V, with a maximum output voltage of 225 V. The switching frequency of 20 kHz was a compromise between mass savings and higher efficiency. Power conversion efficiencies in excess of 0.94 were demonstrated, along with steady state load current regulation of 1 percent. The power electronics were successfully integrated with a 10 kW laboratory hydrogen arcjet, and reliable, nondestructive starts and transitions to steady state operation were demonstrated. The estimated specific mass for a flight packaged unit was 2 kg/kW

Potential Sinks for Geologic Storage of CO2 Generated in the Carolinas

This document summarizes a scoping study of the current state of knowledge of carbon storage options for our geographic area. The focus is on one aspect of carbon capture and storage—identification of deep saline aquifers in which carbon dioxide (CO2 ) generated in the Carolinas might be stored. The study does not address other aspects of CO2 storage projects, such as capture and compression of the gas, well construction and development, or injection. Transport of CO2 is touched upon in this study but has not been fully addressed. The information contained in this document is primarily from review of published geologic literature and unpublished data. No field data collection has been completed as part of this study. Further work will be necessary to increase confidence in the suitability of the potential CO2 storage sites identified in this report. This study does not address the regulatory, environmental, or public policy issues associated with carbon storage, which are under development at this time.Duke Energy, Progress Energy, Santee Cooper Power, South Carolina Electric and Gas, Electric Power Research Institute (EPRI), Southern States Energy Board (SSEB)Bureau of Economic Geolog

The Effect of Dietary Supplementation with Spent Cider Yeast on the Swine Distal Gut Microbiome

peer-reviewedBackground: There is an increasing need for alternatives to antibiotics for promoting animal health, given the increasing problems associated with antibiotic resistance. In this regard, we evaluated spent cider yeast as a potential probiotic for modifying the gut microbiota in weanling pigs using pyrosequencing of 16S rRNA gene libraries. Methodology and Principal Findings: Piglets aged 24–26 days were assigned to one of two study groups; control (n = 12) and treatment (n = 12). The control animals were fed with a basal diet and the treatment animals were fed with basal diet in combination with cider yeast supplement (500 ml cider yeast containing ,7.6 log CFU/ml) for 21 days. Faecal samples were collected for 16s rRNA gene compositional analysis. 16S rRNA compositional sequencing analysis of the faecal samples collected from day 0 and day 21 revealed marked differences in microbial diversity at both the phylum and genus levels between the control and treatment groups. This analysis confirmed that levels of Salmonella and Escherichia were significantly decreased in the treatment group, compared with the control (P,0.001). This data suggest a positive influence of dietary supplementation with live cider yeast on the microbial diversity of the pig distal gut. Conclusions/Significance: The effect of dietary cider yeast on porcine gut microbial communities was characterized for the first time using 16S rRNA gene compositional sequencing. Dietary cider yeast can potentially alter the gut microbiota, however such changes depend on their endogenous microbiota that causes a divergence in relative response to that given diet.This work was funded by Enterprise Ireland, under the Commercialisation Fund (Contract No: CFTD/05/117), the Irish Government under the National Development Plan, 2000–2006, the European Research and Development Fund and Science Foundation Ireland (SFI).European Research and Development Fun

Status of a Power Processor for the Prometheus-1 Electric Propulsion System

NASA is developing technologies for nuclear electric propulsion for proposed deep space missions in support of the Exploration initiative under Project Prometheus. Electrical power produced by the combination of a fission-based power source and a Brayton power conversion and distribution system is used by a high specific impulse ion propulsion system to propel the spaceship. The ion propulsion system include the thruster, power processor and propellant feed system. A power processor technology development effort was initiated under Project Prometheus to develop high performance and lightweight power-processing technologies suitable for the application. This effort faces multiple challenges including developing radiation hardened power modules and converters with very high power capability and efficiency to minimize the impact on the power conversion and distribution system as well as the heat rejection system. This paper documents the design and test results of the first version of the beam supply, the design of a second version of the beam supply and the design and test results of the ancillary supplies

Anti-Salmonella lacatic acid bacteria from porcine intestinal sources

The aim of this study was to isolate lactic acid bacteria (LAB) with anti-Salmonella activity from the porcine gastrointestinal tract (GIT) and to characterise these for potentially probiotic properties using in vitro assays. Porcine caecal and faecal samples were screened for the presence of anti-Salmonella LAB; the ten most promising isolates belonged to the genera Lactobacillus and Pediococcus. The LAB exhibited large variation in their ability to survive in simulated gastric juice at pH 1.85. While Lactobacillus acidophilus species survived at up to 80% for 30 min, Lb. pentosus species declined to less than 0.001%. All isolates tolerated porcine bile at a concentration of 0.3%, with some capable of growth in the presence of up to 5% bile. The ability of the LAB isolates to prevent Salmonella invasion of intestinal epithelial cells varied, with reductions of 55% (Lb. acidophilus spp.) to 82% (Lb. salivarius spp.) observed. The data demonstrates that some porcine intestinal LAB isolates may offer potential as probiotics for the reduction of Salmonella carriage in pigs

The Ursinus Weekly, March 15, 1965

Sig Nu and inactive Demas win Sorority-Fraternity Song Fest • Roving reporter • The grammarian\u27s funeral, or Easy does it • Silent generation whispers, non-quiet editor speaks • Upper classmen reveal soph shingles technique • Editorial: Come on, girls! • A view of fraternity bids • Letter to the editor • Admissions Office, Spring 1960 • Campus song: Addendum • Advice column • To a seminar in Spring • Greek gleaningshttps://digitalcommons.ursinus.edu/weekly/1243/thumbnail.jp

Performance of anti-Salmonella lactic acid bacteria in the porcine intestine

Of five anti-Salmonella porcine cultures administered to pigs at 1010 cfu/day, two Lactobacillus murinus strains demonstrated superior survival during gastrointestinal transit. Both were detected at ~107 -108 cfu/g faeces which was higher (P\u3c0.05) than Pediococcus pentosaceus DPC6006 (~105 cfu/g). One Lb. murinus strain was also excreted at higher numbers (P\u3c0.05) than either Lb. salivarius DPC6005 or Lb. pentosus DPC6004 (both ~106 cfu/g). The Lb. murinus strains persisted in both the faeces and the caecum for at least 9 days post-administration. Animals fed a combination of all five strains at 1010 cfu/day excreted ~107 cfu/g of the administered strains, which was higher (P\u3c0.05) than only P. pentosaceus DPC6006. Randomly amplified polymorphic DNA (RAPD) PCR analysis revealed that both Lb. murinus strains predominated in the faeces of these animals during administration, while post-administration, both Lb. murinus strains and Lb. pentosus DPC6004 were recovered from the faeces and the caecum while P. pentosaceus DPC6006 was only detected in the caecum. After 21 days of culture administration, faecal Enterobacteriaceae counts were reduced in pigs fed Lb. salivarius DPC6005, P. pentosaceus DPC6006, Lb. pentosus DPC6004 and the culture mix, though not significantly. Overall, the porcine intestinal isolates offer potential as probiotics for enteropathogen reduction in pigs; possibly as a combination due to strain variation

Catalog of Galactic Beta Cephei Stars

We present an extensive and up-to-date catalog of Galactic Beta Cephei stars. This catalog is intended to give a comprehensive overview of observational characteristics of all known Beta Cephei stars. 93 stars could be confirmed to be Beta Cephei stars. For some stars we re-analyzed published data or conducted our own analyses. 61 stars were rejected from the final Beta Cephei list, and 77 stars are suspected to be Beta Cephei stars. A list of critically selected pulsation frequencies for confirmed Beta Cephei stars is also presented. We analyze the Beta Cephei stars as a group, such as the distributions of their spectral types, projected rotational velocities, radial velocities, pulsation periods, and Galactic coordinates. We confirm that the majority of these stars are multiperiodic pulsators. We show that, besides two exceptions, the Beta Cephei stars with high pulsation amplitudes are slow rotators. We construct a theoretical HR diagram that suggests that almost all 93 Beta Cephei stars are MS objects. We discuss the observational boundaries of Beta Cephei pulsation and their physical parameters. We corroborate that the excited pulsation modes are near to the radial fundamental mode in frequency and we show that the mass distribution of the stars peaks at 12 solar masses. We point out that the theoretical instability strip of the Beta Cephei stars is filled neither at the cool nor at the hot end and attempt to explain this observation

Selection of porcine intestinal isolates as probiotics for pathogen reduction in pigs

Putative lactobacilli were isolated from the porcine small intestine and assessed in vitro for potential probiotic traits. Viability of all isolates tested was unaffected at porcine bile concentrations of 0.3 % (w/v), with some tolerating up to 3.5 % (w/v) bile. Randomly amplified polymorphic DNA (RAPD) and/or pulsed field gel electrophoresis (PFGE) were used to genetically fingerprint the porcine isolates. Some of these cultures demonstrated antagonistic activity against pathogens Escherichia coli O157:H45 and Salmonella typhimurium DT104 when assayed on agar plates and in co-culture. For example, no Salmonella were detected after 8 h of associative culture with one intestinal isolate,L. salivarius B-24. However, when co-cultured under constant pH conditions, no inhibition was observed, indicating that acid may be one of the mechanisms involved in the antimicrobial activity of this strain. Assessment of these strains is on-going with a view to the development of probiotic feed additives which could potentially reduce pathogen carriage in pigs

Evaluating treatments in health care: The instability of a one-legged stool

<p>Abstract</p> <p>Background</p> <p>Both scientists and the public routinely refer to randomized controlled trials (RCTs) as being the 'gold standard' of scientific evidence. Although there is no question that placebo-controlled RCTs play a significant role in the evaluation of new pharmaceutical treatments, especially when it is important to rule out placebo effects, they have many inherent limitations which constrain their ability to inform medical decision making. The purpose of this paper is to raise questions about <it>over-reliance </it>on RCTs and to point out an additional perspective for evaluating healthcare evidence, as embodied in the Hill criteria. The arguments presented here are generally relevant to all areas of health care, though mental health applications provide the primary context for this essay.</p> <p>Discussion</p> <p>This article first traces the history of RCTs, and then evaluates five of their major limitations: they often lack external validity, they have the potential for increasing health risk in the general population, they are no less likely to overestimate treatment effects than many other methods, they make a relatively weak contribution to clinical practice, and they are excessively expensive (leading to several additional vulnerabilities in the quality of evidence produced). Next, the nine Hill criteria are presented and discussed as a richer approach to the evaluation of health care treatments. Reliance on these multi-faceted criteria requires more analytical thinking than simply examining RCT data, but will also enhance confidence in the evaluation of novel treatments.</p> <p>Summary</p> <p>Excessive reliance on RCTs tends to stifle funding of other types of research, and publication of other forms of evidence. We call upon our research and clinical colleagues to consider additional methods of evaluating data, such as the Hill criteria. Over-reliance on RCTs is similar to resting all of health care evidence on a one-legged stool.</p