Reciprocating Feed System Development Status

The reciprocating feed system (RFS) is an alternative means of providing high pressure propellant flow at low cost and system mass, with high fail-operational reliability. The RFS functions by storing the liquid propellants in large, low-pressure tanks and then expelling each propellant through two or three small, high-pressure tanks. Each RFS tank is sequentially filled, pressurized, expelled, vented, and refilled so as to provide a constant, or variable, mass flow rate to the engine. This type of system is much lighter than a conventional pressure fed system in part due to the greatly reduced amount of inert tank weight. The delivered payload for an RFS is superior to that of conventional pressure fed systems for conditions of high total impulse and it is competitive with turbopump systems, up to approximately 2000 psi. An advanced version of the RFS uses autogenous pressurization and thrust augmentation to achieve higher performance. In this version, the pressurization gases are combusted in a small engine, thus making the pressurization system, in effect, part of the propulsion system. The RFS appears to be much less expensive than a turbopump system, due to reduced research and development cost and hardware cost, since it is basically composed of small high- pressure tanks, a pressurization system, and control valves. A major benefit is the high reliability fail-operational mode; in the event of a failure in one of the three tank-systems, it can operate on the two remaining tanks. Other benefits include variable pressure and flow rates, ease of engine restart in micro-gravity, and enhanced propellant acquisition and control under adverse acceleration conditions. We present a system mass analysis tool that accepts user inputs for various design and mission parameters and calculates such output values payload and vehicle weights for the conventional pressure fed system, the RFS, the Autogenous Pressurization Thrust Augmentation (APTA) RFS, and turbopump systems. Using this tool, a preliminary design of a representative crew exploration vehicle (CEV) has been considered. The design parameters selected for a representative system were modeled after the orbital maneuvering system (OMS) on the Shuttle Orbiter, with an increase of roughly a factor of ten in the delta- V capability and a greater thrust (30,000 lbs, vs. 12,000 lbs). Both storable and cryogenic propellants were considered. Results show that a RFS is a low mass alternative to conventional pressure fed systems, with a substantial increase in payload capability and that it is weight-competitive with turbopump systems at low engine pressure (a few hundred psi); at high engine pressures, the APTA RFS appears to offer the highest payload. We also present the status of the RFS test bed fabrication, assembly, and checkout. This test bed is designed to provide flow rates appropriate for engines in the roughly 10,000 to 30,000 lb thrust range

Analytical Assessment of the Reciprocating Feed System

A preliminary analysis tool has been created in Microsoft Excel to determine deliverable payload mass, total system mass, and performance of spacecraft systems using various types of propellant feed systems. These mass estimates are conducted by inserting into the user interface the basic mission parameters (e.g., thrust, burn time, specific impulse, mixture ratio, etc.), system architecture (e.g., propulsion system type and characteristics, propellants, pressurization system type, etc.), and design properties (e.g., material properties, safety factors, etc.). Different propellant feed and pressurization systems are available for comparison in the program. This gives the user the ability to compare conventional pressure fed, reciprocating feed system (RFS), autogenous pressurization thrust augmentation (APTA RFS), and turbopump systems with the deliverable payload, inert mass, and total system mass being the primary comparison metrics. Analyses of several types of missions and spacecraft were conducted and it was found that the RFS offers a performance improvement, especially in terms of delivered payload, over conventional pressure fed systems. Furthermore, it is competitive with a turbopump system at low to moderate chamber pressures, up to approximately 1,500 psi. Various example cases estimating the system mass and deliverable payload of several types of spacecraft are presented that illustrate the potential system performance advantages of the RFS. In addition, a reliability assessment of the RFS was conducted, comparing it to simplified conventional pressure fed and turbopump systems, based on MIL-STD 756B; these results showed that the RFS offers higher reliability, and thus substantially longer periods between system refurbishment, than turbopump systems, and is competitive with conventional pressure fed systems. This is primarily the result of the intrinsic RFS fail-operational capability with three run tanks, since the system can operate with just two run tanks

Should Mississippi change its flag?

Editorial columns by David R. Bowen, U.S. Representative from Mississippi (D)\u27 1973-1983.https://scholarsjunction.msstate.edu/db-columns/1046/thumbnail.jp

Rapid detection of group B streptococcus and Escherichia coli in amniotic fluid using real-time fluorescent PCR.

OBJECTIVE: To establish reliability and validity of real-time fluorescent PCR for early detection of bacterial invasion of the amniotic cavity. METHODS: Amniotic fluid samples from 40 patients undergoing mid-trimester genetic amniocentesis were incubated for 6 h at 37 degrees C and were cultured on media specific for group B streptococcus (GBS) and E. coli. Concurrently, samples were analyzed with real-time fluorescent PCR (Roche LightCycler) using DNA primers and probes designed to detect the CAMP factor encoding cfb gene and uidA gene of GBS and E. coli, respectively. For positive control and to simulate amniotic fluid colonization, 104 cfu/ml of GBS and E. coli were inoculated on sterile amniotic fluid and incubated for 6 h. Bacterial genomic DNA for the two organisms was extracted and purified via the two-step precipitation method using a commercial kit. The real-time PCR assays were also tested against 25 non-GBS and non-E. coli bacterial species. The lower limit of detection for each pathogen was established using serial dilution of bacterial genomic DNA. RESULTS: All patient samples were negative for evidence of GBS and E. coli with both culture and real-time PCR methods. Amniotic fluid samples inoculated with GBS and E. coli were positive with real-time PCR whereas the 25 bacterial species other than GBS or E. coli tested negative with the assay. Average total sample processing time including the pre-enrichment step was 7 h 40 min. The average cost for DNA extraction and PCR testing was 8.50 dollars per test. CONCLUSION: Real-time fluorescent PCR is a valid and reliable method for detection of specific pathogens in amniotic fluid. This technique is sensitive for low inoculation levels. Real-time fluorescent PCR has potential to impact clinical management as a rapid, reliable detection method for GBS and E. coli in chorioamnionitis

Probing biological nanotopology via diffusion of weakly constrained plasmonic nanorods with optical coherence tomography

Many diseases are characterized by nanostructural changes in connective fibers and soluble proteins, which can indicate or drive disease progression. Noninvasive methods sensitive to nanotopological changes in 3D tissue models can elucidate biophysical changes associated with disease progression. Nanoparticles probe their environment via their diffusion, which is impacted by the size and connectivity of pores into which they freely diffuse. Here, we show that optical coherence tomography provides depth-resolved imaging of gold nanorods (GNRs) to infer local biological nanotopology. We demonstrate the broad potential of this method by sensing changes in diffusion of GNRs in 3D models of mammary ECM and pulmonary mucus

Structure-Based Screen Identifies a Potent Small Molecule Inhibitor of Stat5a/b with Therapeutic Potential for Prostate Cancer and Chronic Myeloid Leukemia.

Bypassing tyrosine kinases responsible for Stat5a/b phosphorylation would be advantageous for therapy development for Stat5a/b-regulated cancers. Here, we sought to identify small molecule inhibitors of Stat5a/b for lead optimization and therapy development for prostate cancer and Bcr-Abl-driven leukemias. In silico screening of chemical structure databases combined with medicinal chemistry was used for identification of a panel of small molecule inhibitors to block SH2 domain-mediated docking of Stat5a/b to the receptor-kinase complex and subsequent phosphorylation and dimerization. We tested the efficacy of the lead compound IST5-002 in experimental models and patient samples of two known Stat5a/b-driven cancers, prostate cancer and chronic myeloid leukemia (CML). The lead compound inhibitor of Stat5-002 (IST5-002) prevented both Jak2 and Bcr-Abl-mediated phosphorylation and dimerization of Stat5a/b, and selectively inhibited transcriptional activity of Stat5a (IC50 = 1.5μmol/L) and Stat5b (IC50 = 3.5 μmol/L). IST5-002 suppressed nuclear translocation of Stat5a/b, binding to DNA and Stat5a/b target gene expression. IST5-002 induced extensive apoptosis of prostate cancer cells, impaired growth of prostate cancer xenograft tumors, and induced cell death in patient-derived prostate cancers when tested ex vivo in explant organ cultures. Importantly, IST5-002 induced robust apoptotic death not only of imatinib-sensitive but also of imatinib-resistant CML cell lines and primary CML cells from patients. IST5-002 provides a lead structure for further chemical modifications for clinical development for Stat5a/b-driven solid tumors and hematologic malignancies

Catching Element Formation In The Act

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions.Comment: 14 pages including 3 figure

Implementation and Conduct of Therapeutic Hypothermia for Perinatal Asphyxial Encephalopathy in the UK – Analysis of National Data

BACKGROUND: Delay in implementing new treatments into clinical practice results in considerable health and economic opportunity costs. Data from the UK TOBY Cooling Register provides the opportunity to examine how one new effective therapy for newborn infants suspected of suffering asphyxial encephalopathy--therapeutic hypothermia- was implemented in the UK. METHODOLOGY/PRINCIPAL FINDINGS: We analysed returned data forms from inception of the Register in December 2006 to the end of July 2011. Data forms were received for 1384 (67%) of the 2069 infants registered. The monthly rate of notifications increased from median {IQR} 18 {15-31} to 33 {30-39} after the announcement of the results of the recent TOBY trial, and to 50 {36-55} after their publication. This rate further increased to 70 {64-83} following official endorsement of the therapy, and is now close to the expected numbers of eligible infants. Cooling was started at 3.3 {1.5-5.5} hours after birth and the time taken to achieve the target 33-34 °C rectal temperature was 1 {0-3} hours. The rectal temperature was in the target range in 83% of measurements. From 2006 to 2011 there was evidence of extension of treatment to slightly less severely affected infants. 278 of 1362 (20%) infants died at 2.9 {1.4-4.1} days of age. The rates of death fell slightly over the period of the Register and, at two years of age cerebral palsy was diagnosed in 22% of infants; half of these were spastic bilateral. Factors independently associated with adverse outcome were clinical seizures prior to cooling (p<0.001) and severely abnormal amplitude integrated EEG (p<0.001). CONCLUSIONS/SIGNIFICANCE: Therapeutic hypothermia was implemented appropriately within the UK, with significant benefit to patients and the health economy. This may be due in part to participation by neonatal units in clinical trials, the establishment of the national Register, and its endorsement by advisory bodies

A genetically anchored physical framework for Theobroma cacao cv. Matina 1-6

<p>Abstract</p> <p>Background</p> <p>The fermented dried seeds of <it>Theobroma cacao </it>(cacao tree) are the main ingredient in chocolate. World cocoa production was estimated to be 3 million tons in 2010 with an annual estimated average growth rate of 2.2%. The cacao bean production industry is currently under threat from a rise in fungal diseases including black pod, frosty pod, and witches' broom. In order to address these issues, genome-sequencing efforts have been initiated recently to facilitate identification of genetic markers and genes that could be utilized to accelerate the release of robust <it>T. cacao </it>cultivars. However, problems inherent with assembly and resolution of distal regions of complex eukaryotic genomes, such as gaps, chimeric joins, and unresolvable repeat-induced compressions, have been unavoidably encountered with the sequencing strategies selected.</p> <p>Results</p> <p>Here, we describe the construction of a BAC-based integrated genetic-physical map of the <it>T. cacao </it>cultivar Matina 1-6 which is designed to augment and enhance these sequencing efforts. Three BAC libraries, each comprised of 10× coverage, were constructed and fingerprinted. 230 genetic markers from a high-resolution genetic recombination map and 96 Arabidopsis-derived conserved ortholog set (COS) II markers were anchored using pooled overgo hybridization. A dense tile path consisting of 29,383 BACs was selected and end-sequenced. The physical map consists of 154 contigs and 4,268 singletons. Forty-nine contigs are genetically anchored and ordered to chromosomes for a total span of 307.2 Mbp. The unanchored contigs (105) span 67.4 Mbp and therefore the estimated genome size of <it>T. cacao </it>is 374.6 Mbp. A comparative analysis with <it>A. thaliana, V. vinifera</it>, and <it>P. trichocarpa </it>suggests that comparisons of the genome assemblies of these distantly related species could provide insights into genome structure, evolutionary history, conservation of functional sites, and improvements in physical map assembly. A comparison between the two <it>T. cacao </it>cultivars Matina 1-6 and Criollo indicates a high degree of collinearity in their genomes, yet rearrangements were also observed.</p> <p>Conclusions</p> <p>The results presented in this study are a stand-alone resource for functional exploitation and enhancement of <it>Theobroma cacao </it>but are also expected to complement and augment ongoing genome-sequencing efforts. This resource will serve as a template for refinement of the <it>T. cacao </it>genome through gap-filling, targeted re-sequencing, and resolution of repetitive DNA arrays.</p