bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Experimental Examination of Cantilevered and Shrouded Stators in a Multistage Axial Compressor
Authors: Swoboda M. , Ivey P. C. , Wenger U. , Gümmer V. 
Published: December 2014

This paper presents experimental investigations on a large-scale low-speed compressor facility with four repeating stages equipped with CDA-profiles (Controlled Diffusion Airfoils). Two different builds were investigated. Both builds used identical rotors, but had stators configured either in cantilevered or in shrouded form.
Traverse measurements of total pressure and flow angle at six axial locations (IGV, two rotor and three stator exit planes) were performed between 1% and 99% annulus height and across two blade pitches. Circumferentially mass-averaged radial profiles were used in a through-flow code for reconstruction analysis of the measurements. In addition to the traverse measurements surface static pressures on stage 3 rotor and stator were measured. The effect of the “free-end” configuration on an embedded stage of this multistage compressor is described and compared to the shrouded configuration. The objective of this study was to investigate the differences of these two configurations and especially the effects caused by the hub clearance vortex in the cantilevered case.
The entire set of measurements and through-flow analysis was performed at two operating points of the compressor i.e. at peak efficiency and near stall condition. Thus also the effects of the hub clearance vortex which influences the stall margin of the compressor are described. The analysis of the results shows slightly higher pressure rise coefficients for shrouded stators, but slightly higher stall margin in the cantilevered case. This is due to a stabilizing effect of the hub clearance vortex (cleans up separation on hub) in the cantilevered configuration because its direction is opposite to the secondary flow in the passage.
Micro Gas Turbine for Combined Heat and Power in Distributed Generation
Authors: Carnö Johanna , Cavani Adrin , Liinanki Leif 
Published: December 2014

Micro gas turbine units are becoming popular for on-site combined heat and power production (CHP). CHP units based on gas turbines have several advantages; low emissions, compactness, low maintenance costs and fuel flexibility. The successful development of a small high-speed turbogenerator gives major opportunities to meet the customers’ demands in a deregulated and competitive market.
Vattenfall, together with Volvo Aero Turbines and ABB, has actively participated in development of a future concept of micro gas turbines. The first demonstration plant in Northern Europe for small scale heat and power co-generation, a 40 kWe turbogenerator was installed by Vattenfall at Pappersgruppen in Gothenburg, Sweden.
A first evaluation phase of the demonstration plant has been performed. The electricity and heat output showed to be 38 kWe and 70 kW respectively at full load. The net plant efficiency was 28.2% and the overall efficiency was 80%, based on the lower heating value. The emissions from the unit were very low due to low emission combustion chamber. The evaluation period will continue during 97/98. The influence of outdoor temperature, degree of loading, as well as the required maintenance and manned operation will be investigated.
Experimental Evaluation of the High-to-Low Speed Transformation Process for a Highly Loaded Core Compressor Stage
Authors: Lyes P. A. , Ginder R. B. 
Published: December 2014

A set of low speed blading has been designed to represent an embedded stage from the DERA C147 high speed research compressor. The aim of the design was to undertake a careful high-to-low speed transformation of the geometry of a high speed stage and evaluate the transformation process through comparing detailed flow measurements taken in both the high and low speed environments.
The high-to-low speed transformation process involves compromises due to both geometric and aerodynamic constraints. Geometric constraints include the parallel annulus of the low speed compressor and also its size and power which restrict the Reynolds number that can be achieved. Aerodynamically the high speed blades have to be subsonic and the effects of Mach number on loss buckets and boundary layer development limit the extent to which a full high-to-low speed match is possible.
The low speed blading has been tested at Cranfield University’s 4-stage research compressor facility. Detailed traverse measurements were taken at rotor and stator exit along with blade surface static pressure measurements and oil flow visualisation. These, along with previous traverse measurements from the C147 compressor, have been used to show that a good comparison of pressure, flow angle, and endwall loss distributions can be achieved despite the compromises inherent in the transformation process. However some interesting differences were apparent and these are discussed.
In addition, 3D flow calculations have been performed on both the rotor and stator using measured inlet conditions. These predictions model the endwall corner flow well. However, further work is needed to obtain better modelling of the clearance flow of both blade rows.
Improved Pt Aluminide Coatings Using CVD and Novel Platinum Electroplating
Authors: Warnes Bruce Michael 
Published: December 2014

Chemical vapor deposition (CVD) is an old coating technology, but it was not successfully utilized to aluminize gas turbine hardware until recently (1989). In CVD aluminizing, the use of multiple, independently controlled, low temperature, external, metal halide generators combined with computer control of all process variables gives flexibility and consistent quality that is not possible with any other aluminizing process.
It has been shown that harmful coating impurities (such as sulfur and boron etc.) can be transported to a coating from a high temperature aluminum source in the coating chamber during aluminizing. Representative processes include: pack cementation, above the pack, SNECMA, and high activity CVD. In contrast, it has also been demonstrated that CVD low activity aluminizing removes harmful impurities (S, P, B & W etc.) from the coating during deposition. Furthermore, clean, low activity coatings (simple aluminide MDC-210 or platinum modified MDC-150L) have been shown to exhibit superior oxidation resistance compared to similar coatings made by other aluminizing processes. A second significant source of impurities in platinum modified aluminide diffusion coatings is electroplating, that is, plating bath components (S, P, CI, K, Ca etc.) are codeposited with the platinum, and these impurities can have either a beneficial (K&Ca) or a detrimental (S,P&Cl) influence upon the oxidation resistance of the product coating.
The results of investigations on the transport of impurities during aluminizing and electroplating, plus the influence of these impurities on oxidation resistance of the product coatings will be presented and discussed.
Effects of Inlet Flow Field Conditions on the Performance of Centrifugal Compressor Diffusers: Part 1 — Discrete-Passage Diffuser
Authors: Filipenco Victor G. , Deniz Sabri , Johnston J. Mark , Greitzer Edward M. , Cumpsty Nicholas A. 
Published: December 2014

This is Part 1 of a two-part paper considering the performance of radial diffusers for use in a high performance centrifugal compressor. Part 1 reports on discrete-passage diffusers (shown in Fig. 1) while Part 2 describes a test of a straight-channel diffuser designed for equivalent duty. Two builds of discrete-passage diffuser were tested, with 30 and 38 separate passages. Both the 30 and 38 passage diffusers investigated showed comparable range of unstalled operation and similar level of overall diffuser pressure recovery.
The paper concentrates on the influence of inlet flow conditions on the pressure recovery and operating range of radial diffusers for centrifugal compressor stages. The flow conditions examined include diffuser inlet Mach number, flow angle, blockage, and axial flow non-uniformity. The investigation was carried out in a specially built test facility, designed to provide a controlled inlet flow field to the test diffusers. The facility can provide a wide range of diffuser inlet velocity profile distortion and skew with Mach numbers up to unity and flow angles of 63° to 75° from the radial direction.
The consequences of different averaging methods for the inlet total pressure distributions, which are needed in the definition of diffuser pressure recovery coefficient for non-uniform diffuser inlet conditions were also assessed. The overall diffuser pressure recovery coefficient, based on suitably averaged inlet total pressure, was found to correlate well with the momentum-averaged flow angle into the diffuser. Furthermore the pressure recovery coefficient was found to be essentially independent of the axial distortion at diffuser inlet, and the Mach number, over the wide flow range (from maximum flow to the beginning of flow instabilities) investigated. It is thus shown that the generally accepted sensitivity of diffuser pressure recovery performance to inlet flow distortion and boundary layer blockage can be largely attributed to inappropriate quantification of the average dynamic pressure at diffuser inlet. Use of an inlet dynamic pressure based on availability or mass-averaging in combination with definition of inlet flow angle based on mass average of the radial and tangential velocity at diffuser inlet removes this sensitivity.
PM2000 Honeycomb Structures
Authors: Brown C. , Verghese E. , Sporer D. , Sellors R. 
Published: December 2014

The use of oxide dispersion strengthened (ODS) superalloys for excellent high temperature oxidation resistance has been well established. This is achieved by the formation of a dense, slowly growing and tightly adherent alumina scale on Fe-Cr-Al and Ni-Cr-Al ODS alloys. The addition of oxide dispersion strengthening confers a structural capability for operation temperatures of up to 1350°C. Traditionally these materials have been used in relatively thick sections where the core “reservoir” of aluminium is adequate to provide a continuous replenishment of the protective oxide coating.
This paper examines the use of one of these materials, PM2000, in thin section structures. In particular it addresses the problem of using thin foils in the manufacture of a typical engineering structure, seal honeycomb. Thin foils in the thickness range 90 to 150μm were tested to explore the oxidation limit under extreme temperature conditions. The results indicate that material life is determined by foil thickness and aluminium content of the alloy. Comparison is drawn with existing typical materials for these applications e.g. Haynes 214.
Pharmacokinetics of LFF571 and Vancomycin in Patients with Moderate Clostridium difficile Infections
Authors: Bhansali Suraj G. , Mullane Kathleen , Ting Lillian S. L. , Leeds Jennifer A. , Dabovic Kristina , Praestgaard Jens , Pertel Peter 
Published: December 2014

ABSTRACT

Clostridium difficile
infection causes diarrheal disease with potentially fatal complications. Although treatments are available, including vancomycin, metronidazole, and fidaxomicin, the recurrence of disease after therapy remains a problem. LFF571 is a novel thiopeptide antibacterial that shows
in vitro
potency against
C. difficile
that is comparable to or greater than that of other clinically used antibiotics. Here, we compare the pharmacokinetics (PK) of LFF571 and vancomycin in patients with
C. difficile
infection as part of an early efficacy study. This multicenter, randomized, evaluator-blind, and active-controlled study evaluated the safety, efficacy, and pharmacokinetics of LFF571 in adults with primary episodes or first relapses of moderate
C. difficile
infections. Patients were randomized to receive 200 mg of LFF571 or 125 mg of vancomycin four times daily for 10 days. The PK parameters were calculated from drug concentrations measured in serum and fecal samples. The systemic exposure following oral administration of 200 mg of LFF571 four times per day for 10 days in patients with
C. difficile
infection was limited. The highest LFF571 serum concentration observed was 41.7 ng/ml, whereas the levels in feces at the end of treatment were between 107 and 12,900 μg/g. In comparison, the peak vancomycin level observed in serum was considerably higher, at 2.73 μg/ml; the levels of vancomycin in feces were not measured. Similar to healthy volunteers, patients with
C. difficile
infections exhibited high fecal concentrations and low serum levels of LFF571. These results are consistent with the retention of LFF571 in the lumen of the gastrointestinal tract. (This study has been registered at ClinicalTrials.gov under registration no. NCT01232595.)
Characterization of the Novel DNA Gyrase Inhibitor AZD0914: Low Resistance Potential and Lack of Cross-Resistance in Neisseria gonorrhoeae
Authors: Alm Richard A. , Lahiri Sushmita D. , Kutschke Amy , Otterson Linda G. , McLaughlin Robert E. , Whiteaker James D. , Lewis Lisa A. , Su Xiaohong , Huband Michael D. , Gardner Humphrey , Mueller John P. 
Published: December 2014

ABSTRACT

The unmet medical need for novel intervention strategies to treat
Neisseria gonorrhoeae
infections is significant and increasing, as rapidly emerging resistance in this pathogen is threatening to eliminate the currently available treatment options. AZD0914 is a novel bacterial gyrase inhibitor that possesses potent
in vitro
activities against isolates with high-level resistance to ciprofloxacin and extended-spectrum cephalosporins, and it is currently in clinical development for the treatment of
N. gonorrhoeae
infections. The propensity to develop resistance against AZD0914 was examined in
N. gonorrhoeae
and found to be extremely low, a finding supported by similar studies with
Staphylococcus aureus
. The genetic characterization of both first-step and second-step mutants that exhibited decreased susceptibilities to AZD0914 identified substitutions in the conserved GyrB TOPRIM domain, confirming DNA gyrase as the primary target of AZD0914 and providing differentiation from fluoroquinolones. The analysis of available bacterial gyrase and topoisomerase IV structures, including those bound to fluoroquinolone and nonfluoroquinolone inhibitors, has allowed the rationalization of the lack of cross-resistance that AZD0914 shares with fluoroquinolones. Microbiological susceptibility data also indicate that the topoisomerase inhibition mechanisms are subtly different between
N. gonorrhoeae
and other bacterial species. Taken together, these data support the progression of AZD0914 as a novel treatment option for the oral treatment of
N. gonorrhoeae
infections.
Exopolysaccharide Production and Ropy Phenotype Are Determined by Two Gene Clusters in Putative Probiotic Strain Lactobacillus paraplantarum BGCG11
Authors: Zivkovic Milica , Miljkovic Marija , Ruas-Madiedo Patricia , Strahinic Ivana , Tolinacki Maja , Golic Natasa , Kojic Milan 
Published: December 2014

ABSTRACT

Lactobacillus paraplantarum
BGCG11, a putative probiotic strain isolated from a soft, white, artisanal cheese, produces a high-molecular-weight heteropolysaccharide, exopolysaccharide (EPS)-CG11, responsible for the ropy phenotype and immunomodulatory activity of the strain. In this study, a 26.4-kb region originating from the pCG1 plasmid, previously shown to be responsible for the production of EPS-CG11 and a ropy phenotype, was cloned, sequenced, and functionally characterized. In this region 16 putative open reading frames (ORFs), encoding enzymes for the production of EPS-CG11, were organized in specific loci involved in the biosynthesis of the repeat unit, polymerization, export, regulation, and chain length determination. Interestingly, downstream of the
eps
gene cluster, a putative transposase gene was identified, followed by an additional
rfb
gene cluster containing the
rfbACBD
genes, the ones most probably responsible for dTDP-
l
-rhamnose biosynthesis. The functional analysis showed that the production of the high-molecular-weight fraction of EPS-CG11 was absent in two knockout mutants, one in the
eps
and the other in the
rfb
gene cluster, as confirmed by size exclusion chromatography analysis. Therefore, both
eps
and
rfb
genes clusters are prerequisites for the production of high-molecular-weight EPS-CG11 and for the ropy phenotype of strain
L. paraplantarum
BGCG11.
Community Structure and Biogeochemical Impacts of Microbial Life on Floating Pumice
Authors: Elser J. J. , Bastidas Navarro M. , Corman J. R. , Emick H. , Kellom M. , Laspoumaderes C. , Lee Z. M. , Poret-Peterson A. T. , Balseiro E. , Modenutti B. 
Published: December 2014

ABSTRACT
Volcanic eruptions are a widespread force of geological and ecological disturbance and present recurrent opportunities for the study of biological responses to novel habitat formation. However, scientific study of such events is difficult given their short duration and often distant location. Here we report results from opportunistic sampling of unique volcano-generated habitats formed during the 2011 explosive eruption in the Puyehue-Cordón Caulle complex (Chile), when massive amounts of pumice were ejected, creating novel floating substrata that have never before been characterized from a microbiological perspective. DNA sequencing revealed a dynamic community of microbes that came to inhabit the pumice, with a unique composition distinct from that of the lakes' surface waters and with suggestions of ecological convergence across lakes and sampling times. Furthermore, biogeochemical studies of net nutrient fluxes showed that, while the fresh pumice arriving to the lakes was an initial source of phosphorus (P), colonized pumice had high rates of nitrogen (N) and P uptake and was sufficiently abundant to represent a significant lake-wide nutrient sink. These findings highlight the remarkable versatility of microbes in exploiting novel environments and are consistent with a recent proposal of floating pumice as a favorable environment for the initial origins of life on early Earth.
Genetic Engineering Activates Biosynthesis of Aromatic Fumaric Acid Amides in the Human Pathogen Aspergillus fumigatus
Authors: Kalb Daniel , Heinekamp Thorsten , Lackner Gerald , Scharf Daniel H. , Dahse Hans-Martin , Brakhage Axel A. , Hoffmeister Dirk 
Published: December 2014

ABSTRACT

The
Aspergillus fumigatus
nonribosomal peptide synthetase FtpA is among the few of this species whose natural product has remained unknown. Both FtpA adenylation domains were characterized
in vitro
. Fumaric acid was identified as preferred substrate of the first and both
l
-tyrosine and
l
-phenylalanine as preferred substrates of the second adenylation domain. Genetically engineered
A. fumigatus
strains expressed either
ftpA
or the regulator gene
ftpR
, encoded in the same cluster of genes, under the control of the doxycycline-inducible tetracycline-induced transcriptional activation (tet-on) cassette. These strains produced fumaryl-
l
-tyrosine and fumaryl-
l
-phenylalanine which were identified by liquid chromatography and high-resolution mass spectrometry. Modeling of the first adenylation domain
in silico
provided insight into the structural requirements to bind fumaric acid as peptide synthetase substrate. This work adds aromatic fumaric acid amides to the secondary metabolome of the important human pathogen
A. fumigatus
which was previously not known as a producer of these compounds.
Using a Genome-Scale Metabolic Model of Enterococcus faecalis V583 To Assess Amino Acid Uptake and Its Impact on Central Metabolism
Authors: Veith Nadine , Solheim Margrete , van Grinsven Koen W. A. , Olivier Brett G. , Levering Jennifer , Grosseholz Ruth , Hugenholtz Jeroen , Holo Helge , Nes Ingolf , Teusink Bas , Kummer Ursula 
Published: December 2014

ABSTRACT

Increasing antibiotic resistance in pathogenic bacteria necessitates the development of new medication strategies. Interfering with the metabolic network of the pathogen can provide novel drug targets but simultaneously requires a deeper and more detailed organism-specific understanding of the metabolism, which is often surprisingly sparse. In light of this, we reconstructed a genome-scale metabolic model of the pathogen
Enterococcus faecalis
V583. The manually curated metabolic network comprises 642 metabolites and 706 reactions. We experimentally determined metabolic profiles of
E. faecalis
grown in chemically defined medium in an anaerobic chemostat setup at different dilution rates and calculated the net uptake and product fluxes to constrain the model. We computed growth-associated energy and maintenance parameters and studied flux distributions through the metabolic network. Amino acid auxotrophies were identified experimentally for model validation and revealed seven essential amino acids. In addition, the important metabolic hub of glutamine/glutamate was altered by constructing a glutamine synthetase knockout mutant. The metabolic profile showed a slight shift in the fermentation pattern toward ethanol production and increased uptake rates of multiple amino acids, especially
l
-glutamine and
l
-glutamate. The model was used to understand the altered flux distributions in the mutant and provided an explanation for the experimentally observed redirection of the metabolic flux. We further highlighted the importance of gene-regulatory effects on the redirection of the metabolic fluxes upon perturbation. The genome-scale metabolic model presented here includes gene-protein-reaction associations, allowing a further use for biotechnological applications, for studying essential genes, proteins, or reactions, and the search for novel drug targets.
Prevalence of Carriage of Shiga Toxin-Producing Escherichia coli Serotypes O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28 among Slaughtered Adult Cattle in France
Authors: Bibbal Delphine , Loukiadis Estelle , Kérourédan Monique , Ferré Franck , Dilasser Françoise , Peytavin de Garam Carine , Cartier Philippe , Oswald Eric , Gay Emilie , Auvray Frédéric , Brugère Hubert 
Published: December 2014

ABSTRACT

The main pathogenic enterohemorrhagic
Escherichia coli
(EHEC) strains are defined as Shiga toxin (Stx)-producing
E. coli
(STEC) belonging to one of the following serotypes: O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28. Each of these five serotypes is known to be associated with a specific subtype of the intimin-encoding gene (
eae
). The objective of this study was to evaluate the prevalence of bovine carriers of these “top five” STEC in the four adult cattle categories slaughtered in France. Fecal samples were collected from 1,318 cattle, including 291 young dairy bulls, 296 young beef bulls, 337 dairy cows, and 394 beef cows. A total of 96
E. coli
isolates, including 33 top five STEC and 63 atypical enteropathogenic
E. coli
(aEPEC) isolates, with the same genetic characteristics as the top five STEC strains except that they lacked an
stx
gene, were recovered from these samples. O157:H7 was the most frequently isolated STEC serotype. The prevalence of top five STEC (all serotypes included) was 4.5% in young dairy bulls, 2.4% in young beef bulls, 1.8% in dairy cows, and 1.0% in beef cows. It was significantly higher in young dairy bulls (
P
< 0.05) than in the other 3 categories. The basis for these differences between categories remains to be elucidated. Moreover, simultaneous carriage of STEC O26:H11 and STEC O103:H2 was detected in one young dairy bull. Lastly, the prevalence of bovine carriers of the top five STEC, evaluated through a weighted arithmetic mean of the prevalence by categories, was estimated to 1.8% in slaughtered adult cattle in France.