bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unsteady CFD Analysis of Turbulent Flow and Heat Transfer in a Gas Turbine Blade Trailing Edge Subjected to Rotation
Authors: Borello Domenico , Delibra Giovanni , Bianchini Cosimo , Andreini Antonio 
Published: August 2013

Internal cooling of gas turbine blade represents a challenging task involving several different phenomena as, among others, highly three-dimensional unsteady fluid flow, efficient heat transfer and structural design. This paper focuses on the analysis of the turbulent flow and heat transfer inside a typical wedge–shaped trailing edge cooling duct of a gas turbine blade. In the configuration under scrutiny the coolant flows inside the duct in radial direction and it leaves the blade through the trailing edge after a 90 deg turning.
At first an analysis of the flow and thermal fields in stationary conditions was carried out. Then the effects of rotational motion were investigated for a rotation number of 0.275. The rotation axis here considered is normal to the inflow and outflow bulk velocity, representing schematically a highly loaded blade configuration.
The work aimed to i) analyse the dynamic of the vortical structures under the influence of strong body forces and the constraints induced by the internal geometry and ii) to study the impact of such motions on the mechanisms of heat removal. The final aim was to verify the design of the equipment and to detect the possible presence of regions subjected to high thermal loads.
The analysis is carried out using the well assessed open source code OpenFOAM written in C++ and widely validated by several scientists and researchers around the world. The unsteadiness of the flow inside the trailing edge required to adopt models that accurately reconstructed the flow field. As the computational costs associated to LES (especially in the near wall regions) largely exceed the available resources, we chose for the simulation the SAS model of Menter, that was validated in a series of benchmark and industrially relevant test cases and allowed to reconstruct a part of the turbulence spectra through a scale-adaptive mechanism. Assessment of the obtained results with steady-state k-ω SST computations and available experimental results was carried out.
The present analysis demonstrated that a strong unsteadiness develops inside the trailing edge and that the rotation generated strong secondary motions that enhanced the dynamic of heat removal, leading to a less severe temperature distribution on the heated surface w.r.t the non rotating case.
Time-Averaged and Time-Accurate Aerodynamic Effects of Forward Rotor Cavity Purge Flow for a High-Pressure Turbine: Part I—Analytical and Experimental Comparisons
Authors: Green Brian R. , Mathison Randall M. , Dunn Michael G. 
Published: August 2013

The effect of rotor purge flow on the unsteady aerodynamics of a high-pressure turbine stage operating at design corrected conditions has been investigated both experimentally and computationally. The experimental configuration consisted of a single-stage high-pressure turbine with a modern film-cooling configuration on the vane airfoil as well as the inner and outer end-wall surfaces. Purge flow was introduced into the cavity located between the high-pressure vane and the high-pressure disk. The high-pressure blades and the downstream low-pressure turbine nozzle row were not cooled. All hardware featured an aerodynamic design typical of a commercial high-pressure ratio turbine, and the flow path geometry was representative of the actual engine hardware. In addition to instrumentation in the main flow path, the stationary and rotating seals of the purge flow cavity were instrumented with high frequency response, flush-mounted pressure transducers and miniature thermocouples to measure flow field parameters above and below the angel wing.
Predictions of the time-dependent flow field in the turbine flow path were obtained using FINE/Turbo, a three-dimensional, Reynolds-Averaged Navier-Stokes CFD code that had the capability to perform both steady and unsteady analysis. The steady and unsteady flow fields throughout the turbine were predicted using a three blade-row computational model that incorporated the purge flow cavity between the high-pressure vane and disk. The predictions were performed in an effort to mimic the design process with no adjustment of boundary conditions to better match the experimental data. The time-accurate predictions were generated using the harmonic method. Part I of this paper concentrates on the comparison of the time-averaged and time-accurate predictions with measurements in and around the purge flow cavity. The degree of agreement between the measured and predicted parameters is described in detail, providing confidence in the predictions for flow field analysis that will be provided in Part II.
Time-Averaged and Time-Accurate Aerodynamic Effects of Rotor Purge Flow for a Modern, One and One-Half Stage High-Pressure Turbine: Part II—Analytical Flow Field Analysis
Authors: Green Brian R. , Mathison Randall M. , Dunn Michael G. 
Published: August 2013

The detailed mechanisms of purge flow interaction with the hot-gas flow path were investigated using both unsteady CFD and measurements for a turbine operating at design corrected conditions. This turbine consisted of a single-stage high-pressure turbine and the downstream, low-pressure turbine nozzle row with an aerodynamic design equivalent to actual engine hardware and typical of a commercial, high-pressure ratio, transonic turbine. The high-pressure vane airfoils and inner and outer endwalls incorporated state-of-the-art film cooling, and purge flow was introduced into the cavity located between the high-pressure vane and disk. The flow field above and below the blade angel wing was characterized by both temperature and pressure measurements. Predictions of the time-dependent flow field were obtained using a three-dimensional, Reynolds-Averaged Navier-Stokes CFD code and a computational model incorporating the three blade rows and the purge flow cavity. The predictions were performed to evaluate the accuracy obtained by a design style application of the code, and no adjustment of boundary conditions was made to better match the experimental data.
Part I of this paper compared the predictions to the measurements in and around the purge flow cavity and demonstrated good correlation. Part II of this paper concentrates on the analytical results, looking at the primary gas path ingestion mechanism into the cavity as well as the effects of the rotor purge on the upstream vane and downstream rotor aerodynamics and thermodynamics. Ingestion into the cavity is driven by high static pressure regions downstream of the vane, high-velocity flow coming off the pressure side of the vane, and the blade bow waves. The introduction of the purge flow is seen to have an effect on the static pressure of the vane trailing edge in the lower 5% of span. In addition, the purge flow is weak enough that upon exiting the cavity, it is swept into the mainstream flow and provides no additional cooling benefits on the platform of the rotating blade.
Large Eddy Simulation of Film Cooling Flows Using Octree Hexahedral Meshes
Authors: Fujimoto Shu 
Published: August 2013

Today, high temperatures are needed for the inlet gas of turbines to increase the efficiency of gas turbines. The vanes and blades of a turbine that are exposed to hot gas must be cooled, and film cooling is now being widely applied to gas turbines because of its high cooling effectiveness. Recently, numerous researchers have conducted numerical simulations of film cooling flows using Reynolds-averaged Navier–Stokes (RANS) simulation, detached eddy simulation (DES), and large eddy simulation (LES) turbulence models, along with structured and/or unstructured meshes. In fact, for cooling designers, both the prediction accuracy and turnaround time (TAT) of their mesh generations are important to speedily and repeatedly optimize the locations of film cooling holes and shapes. Several researchers have examined the prediction accuracy and effectiveness of film cooling flows in case of RANS in order to minimize the TAT of mesh generation such as for unstructured meshes. However, few papers have considered LES.
In this paper, the open-source computational fluid dynamics (CFD) toolkit OpenFOAM [17] is used as the solver, and LES is used to numerically simulate the film cooling flow into the zero-pressure gradient cross-flow on a flat plate from cylindrical holes, which is one of the most typical and basic test cases. LES is used because of its ability to capture the flow unsteadiness and non-uniformity observed in film cooling flows. In addition, surface-adjusted octree hexahedral meshes, which are relatively easy to generate automatically are used. The mesh generation tool used in this study is snappyHexMesh, which is included in OpenFOAM. The experimental data presented by Sinha et al. [15] are used. Because the film cooling effectiveness strongly depends on certain parameters and conditions, those of the simulated film cooling flow are set to the experimental parameters and conditions as closely as possible. In this study, the density ratio DR is set to 2.0, and the blowing ratio BR is set to 0.5 and 1.0 with the steady cross-flow inlet. In addition, a case is considered where BR = 0.5 (DR = 2.0), with an unsteady turbulent cross-flow inlet.
In the case of LES, the results obtained using the octree hexahedral meshes are compared with those of the experiment and my previous film cooling study (Fujimoto [32]), which was conducted using multiblock structured meshes. The results show that the prediction accuracy using the octree hexahedral meshes is equivalent to that using the multiblock structured meshes, even though the mesh generation TAT is significantly smaller.
Comparison of the FDA-Approved CDC DENV-1-4 Real-Time Reverse Transcription-PCR with a Laboratory-Developed Assay for Dengue Virus Detection and Serotyping
Authors: Waggoner Jesse J. , Abeynayake Janaki , Sahoo Malaya K. , Gresh Lionel , Tellez Yolanda , Gonzalez Karla , Ballesteros Gabriela , Guo Frances P. , Balmaseda Angel , Karunaratne Kumudu , Harris Eva , Pinsky Benjamin A. 
Published: August 2013

ABSTRACT
Dengue virus (DENV) is the agent of the most common vector-borne disease worldwide. Using 199 clinical samples collected from Nicaragua and Sri Lanka, a laboratory-developed DENV multiplex real-time reverse transcription-PCR (rRT-PCR) proved more clinically sensitive than the FDA-approved CDC assay for DENV serotypes 1 to 4 when measured against a composite reference standard, with sensitivities of 97.4% versus 87.1%, respectively.
Reverse Transcription-PCR–Electrospray Ionization Mass Spectrometry for Rapid Detection of Biothreat and Common Respiratory Pathogens
Authors: Jeng Kevin , Hardick Justin , Rothman Richard , Yang Samuel , Won Helen , Peterson Stephen , Hsieh Yu-Hsiang , Masek Billie Jo , Carroll Karen C. , Gaydos Charlotte A. 
Published: August 2013

ABSTRACTElectrospray ionization mass spectrometry (ESI-MS) analysis of reverse transcription (RT)-PCR amplicons from human respiratory samples allows for broad pathogen identification approximately 8 h after collection. We investigated the performance characteristics of a high-throughput RT-PCR-coupled ESI-MS assay for distinguishing biothreat (BT) agents from common bacterial, fungal, and viral respiratory pathogens in bronchoalveolar lavage (BAL) fluid specimens from subjects with suspected respiratory infections. In a retrospective case series, 202 BAL fluid specimens were collected at the Johns Hopkins Hospital between August 2010 and February 2011 from patients with suspected acute respiratory infections. Samples were processed using standard bacterial, viral, and fungal testing in the clinical microbiology laboratory as part of routine care and then were blindly spiked with either water or nucleic acids from BT organisms (Bacillus anthracis,Yersinia pestis,Francisella tularensis,Brucellaspp.,Burkholderiaspp., andRickettsia prowazekii) and tested by RT-PCR–ESI-MS. The sensitivities and specificities of RT-PCR–ESI-MS versus standard clinical methods were as follows: for mock BT DNA, 98.5% sensitivity (95% confidence interval [CI], 94.2 to 99.7%) and 100% specificity (95% CI, 93.1 to 100.0%); for bacterial pathogens, 81.8% sensitivity (95% CI, 74.3 to 87.6%) and 73.6% specificity (95% CI, 64.2 to 81.4%); for viral pathogens, 93.3% sensitivity (95% CI, 66.0 to 99.7%) and 97.3% specificity (95% CI, 89.7 to 99.5%); for fungal pathogens, 42.6% sensitivity (95% CI, 29.5 to 56.7%) and 97.8% specificity (95% CI, 91.8 to 99.6%). Our data suggest that RT-PCR–ESI-MS is a useful adjunct to standard culture protocols for rapid detection of both BT and common respiratory pathogens; further study is required for assay validation, especially for fungal detection, and potential implementation.
Identification and Subtyping of Clinically Relevant Human and Ruminant Mycoplasmas by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry
Authors: Pereyre S. , Tardy F. , Renaudin H. , Cauvin E. , Del Prá Netto Machado L. , Tricot A. , Benoit F. , Treilles M. , Bébéar C. 
Published: August 2013

ABSTRACT

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) recently emerged as a technology for the identification of bacteria. In this study, we aimed to evaluate its applicability to human and ruminant mycoplasmal identification, which can be demanding and time-consuming when using phenotypic or molecular methods. In addition, MALDI-TOF MS was tested as a subtyping tool for certain species. A total of 29 main spectra (MSP) from 10 human and 13 ruminant mycoplasma (sub)species were included in a mycoplasma MSP database to complete the Bruker MALDI Biotyper database. After broth culture and protein extraction, MALDI-TOF MS was applied for the identification of 119 human and 143 ruminant clinical isolates that were previously identified by antigenic or molecular methods and for subcultures of 73 ruminant clinical specimens that potentially contained several mycoplasma species. MALDI-TOF MS resulted in accurate (sub)species-level identification with a score of ≥1.700 for 96% (251/262) of the isolates. The phylogenetically closest (sub)species were unequivocally distinguished. Although mixtures of the strains were reliably detected up to a certain cellular ratio, only the predominant species was identified from the cultures of polymicrobial clinical specimens. For typing purposes, MALDI-TOF MS proved to cluster
Mycoplasma bovis
and
Mycoplasma agalactiae
isolates by their year of isolation and genome profiles, respectively, and
Mycoplasma pneumoniae
isolates by their adhesin P1 type. In conclusion, MALDI-TOF MS is a rapid, reliable, and cost-effective method for the routine identification of high-density growing mycoplasmal species and shows promising prospects for its capacity for strain typing.
Evaluation of the Clinical Performance of the cobas 4800 HPV Test in Patients Referred for Colposcopy
Authors: White Christine , Keegan Helen , Pilkington Loretto , Ruttle Carmel , Kerr Patrick , Sharp Linda , O'Toole Sharon , Turner Michael , Prendiville Walter , D'Arcy Tom , Fitzpatrick Myra , Lenehan Peter , Flannelly Grainne , O'Leary John J. , Martin Cara M. 
Published: August 2013

ABSTRACT
The clinical performance of the cobas human papillomavirus (HPV) test for detection of high-grade disease in a colposcopy-referred population was compared with that of Hybrid Capture 2 (HC2). The overall agreement between the tests was 92.3%. Clinical sensitivity and specificity for detection of cervical intraepithelial neoplasia grade 2 or greater (CIN2+) were 90.0% and 55.5% for cobas and 90.5% and 50.2% for HC2, respectively. In conclusion, both tests showed comparable performance for detection of CIN2+.
Cellular mRNA Decay Protein AUF1 Negatively Regulates Enterovirus and Human Rhinovirus Infections
Authors: Cathcart Andrea L. , Rozovics Janet M. , Semler Bert L. 
Published: August 2013

ABSTRACT

To successfully complete their replication cycles, picornaviruses modify several host proteins to alter the cellular environment to favor virus production. One such target of viral proteinase cleavage is AU-rich binding factor 1 (AUF1), a cellular protein that binds to AU-rich elements, or AREs, in the 3′ noncoding regions (NCRs) of mRNAs to affect the stability of the RNA. Previous studies found that, during poliovirus or human rhinovirus infection, AUF1 is cleaved by the viral proteinase 3CD and that AUF1 can interact with the long 5′ NCR of these viruses
in vitro
. Here, we expand on these initial findings to demonstrate that all four isoforms of AUF1 bind directly to stem-loop IV of the poliovirus 5′ NCR, an interaction that is inhibited through proteolytic cleavage of AUF1 by the viral proteinase 3CD. Endogenous AUF1 was observed to relocalize to the cytoplasm of infected cells in a viral protein 2A-driven manner and to partially colocalize with the viral protein 3CD. We identify a negative role for AUF1 in poliovirus infection, as AUF1 inhibited viral translation and, ultimately, overall viral titers. Our findings also demonstrate that AUF1 functions as an antiviral factor during infection by coxsackievirus or human rhinovirus, suggesting a common mechanism that targets these related picornaviruses.
The Surface Glycoprotein of Feline Leukemia Virus Isolate FeLV-945 Is a Determinant of Altered Pathogenesis in the Presence or Absence of the Unique Viral Long Terminal Repeat
Authors: Bolin Lisa L. , Ahmad Shamim , Lobelle-Rich Patricia A. , Ooms Tara G. , Alvarez-Hernandez Xavier , Didier Peter J. , Levy Laura S. 
Published: August 2013

ABSTRACTFeline leukemia virus (FeLV) is a naturally transmitted gammaretrovirus that infects domestic cats. FeLV-945, the predominant isolate associated with non-T-cell disease in a natural cohort, is a member of FeLV subgroup A but differs in sequence from the FeLV-A prototype, FeLV-A/61E, in the surface glycoprotein (SU) and long terminal repeat (LTR). Substitution of the FeLV-945 LTR into FeLV-A/61E resulted in pathogenesis indistinguishable from that of FeLV-A/61E, namely, thymic lymphoma of T-cell origin. In contrast, substitution of both FeLV-945 LTR and SU into FeLV-A/61E resulted in multicentric lymphoma of non-T-cell origin. These results implicated the FeLV-945 SU as a determinant of pathogenic spectrum. The present study was undertaken to test the hypothesis that FeLV-945 SU can act in the absence of other unique sequence elements of FeLV-945 to determine the disease spectrum. Substitution of FeLV-A/61E SU with that of FeLV-945 altered the clinical presentation and resulted in tumors that demonstrated expression of CD45R in the presence or absence of CD3. Despite the evident expression of CD45R, a typical B-cell marker, T-cell receptor beta (TCRβ) gene rearrangement indicated a T-cell origin. Tumor cells were detectable in bone marrow and blood at earlier times during the disease process, and the predominant SU genes from proviruses integrated in tumor DNA carried markers of genetic recombination. The findings demonstrate that FeLV-945 SU alters pathogenesis, although incompletely, in the absence of FeLV-945 LTR. Evidence demonstrates that FeLV-945 SU and LTR are required together to fully recapitulate the distinctive non-T-cell disease outcome seen in the natural cohort.
The Murine Model for Hantaan Virus-Induced Lethal Disease Shows Two Distinct Paths in Viral Evolutionary Trajectory with and without Ribavirin Treatment
Authors: Chung Dong-Hoon , Västermark Åke , Camp Jeremy V. , McAllister Ryan , Remold Susanna K. , Chu Yong-Kyu , Bruder Carl , Jonsson Colleen B. 
Published: August 2013

ABSTRACTIn vitro, ribavirin acts as a lethal mutagen in Hantaan virus (HTNV)-infected Vero E6 cells, resulting in an increased mutation load and viral population extinction. In this study, we asked whether ribavirin treatment in the lethal, suckling mouse model of HTNV infection would act similarly. The HTNV genomic RNA (vRNA) copy number and infectious virus were measured in lungs of untreated and ribavirin-treated mice. In untreated, HTNV-infected mice, the vRNA copy number increased for 10 days postinfection (dpi) and thereafter remained constant through 26 dpi. Surprisingly, in ribavirin-treated, HTNV-infected mice, vRNA levels were similar to those in untreated mice between 10 and 26 dpi. Infectious virus levels, however, were different: in ribavirin-treated mice, the amount of infectious HTNV was significantly decreased relative to that in untreated mice, suggesting that ribavirin reduced the specific infectivity of the virus (amount of infectious virus produced per vRNA copy). Mutational analysis revealed a ribavirin-associated elevation in mutation frequency in HTNV vRNA similar to that previously reportedin vitro. Codon-based analyses of rates of nonsynonymous (dN) and synonymous (dS) substitutions in the S segment revealed a positive selection for codons within the HTNV N protein gene in the ribavirin-treated vRNA population. In contrast, the vRNA population in untreated, HTNV-infected mice showed a lower level of diversity, reflecting purifying selection for the wild-type genome. In summary, these experiments show two different evolutionary paths thatHantavirusmay take during infection in a lethal murine model of disease, as well as the importance of thein vivohost environment in the evolution of the virus, which was not apparent in our priorin vitromodel system.
Effects of the Number of Genome Segments on Primary and Systemic Infections with a Multipartite Plant RNA Virus
Authors: Sánchez-Navarro Jesús A. , Zwart Mark P. , Elena Santiago F. 
Published: August 2013

ABSTRACT

Multipartite plant viruses were discovered because of discrepancies between the observed dose response and predictions of the independent-action hypothesis (IAH) model. Theory suggests that the number of genome segments predicts the shape of the dose-response curve, but a rigorous test of this hypothesis has not been reported. Here,
Alfalfa mosaic
virus
(AMV), a tripartite
Alfamovirus
, and transgenic
Nicotianatabacum
plants expressing no (wild type), one (P2), or two (P12) viral genome segments were used to test whether the number of genome segments necessary for infection predicts the dose response. The dose-response curve of wild-type plants was steep and congruent with the predicted kinetics of a multipartite virus, confirming previous results. Moreover, for P12 plants, the data support the IAH model, showing that the expression of virus genome segments by the host plant can modulate the infection kinetics of a tripartite virus to those of a monopartite virus. However, the different types of virus particles occurred at different frequencies, with a ratio of 116:45:1 (RNA1 to RNA2 to RNA3), which will affect infection kinetics and required analysis with a more comprehensive infection model. This analysis showed that each type of virus particle has a different probability of invading the host plant, at both the primary- and systemic-infection levels. While the number of genome segments affects the dose response, taking into consideration differences in the infection kinetics of the three types of AMV particles results in a better understanding of the infection process.