bluuebunny/crossref_metadata_2025_split huggingface dataset:
FE-Mesh Effect of the Volume Based Weakest-Link Fatigue Probability Applied to a Compressor Blade
Authors: Sadek Salar , Sandberg Daniel , Olsson Mårten 
Published: December 2013

When dealing with design process of compressor blades, predominantly deterministic models are used for High Cycle Fatigue (HCF) investigations. The existing scatter in factors such as material inhomogeneity of the blade material and loading condition is accounted for by safety factors that often end up in conservative designs. An alternative way to account for these uncertainties is the application of probabilistic models. More information about the scatter in different sources together with probabilistic models can lead to a more robust design process.
In order to compute the stresses acting in a compressor blade, the Finite Element (FE) method is widely used as standard tool. This method may show mesh dependence. Therefore, mesh requirements always exist in FE computations.
In this work, a probabilistic HCF investigation is carried out for a transonic compressor rotor blade. The sensitivity of the volume based weakest-link probabilistic model (WL) due to different mesh properties of the blade is investigated. The goal is to provide advice for better finite element meshing of the blades based on linear type solid elements for the computation of stress history. The mesh types of the blade are the input parameters for the probabilistic HCF investigation.
A stress invariant based HCF local criterion, Sines, and a critical plane criterion, Findley, are used in weakest-link to describe the failure probability for the 12% Cr-steel material used for the compressor blade. The estimation of the weakest-link and the local HCF criteria material parameters are performed using HCF experimental data based on 2 million load cycles obtained for smooth and notched specimens.
The study shows that the choice of the mesh property through the thickness of the compressor blade has much more effect on the failure probability predictions compared to the in-plane mesh property of the blade.
Forced Response of a Mistuned Industrial Impeller With Two Different Blade Geometries, via ROM
Authors: Boulton Luis A. , Casanova Euro 
Published: December 2013

Numerous works have presented techniques for obtaining reduced order models (ROMs) of mistuned bladed disks. Most of these works focus in only one rotor’s stage, though some also include several stages and even the rotor shaft. However, to the authors’ knowledge, the ROM techniques available in the literature consider only one blade geometry by stage, thus making impossible their use for the case of impellers with two or more different blade geometries.
This paper shows an adaptation of a previously published reduced order modeling technique in order to allow its application to the case of industrial compressor impellers incorporating two or more different blade geometries (main and splitter blades). The technique is based on Craig and Bampton’s component mode synthesis and it permits to introduce different mistuning patterns for each blade geometry while the disk is considered as a cyclic symmetric structure.
The proposed technique is applied to an industrial compressor impeller in order to assess its precision and validity. Generation of finite element parent model for the real compressor via laser scanning is presented and discussed as well as simplifications used in order to generate the impeller’s ROM. Validation is carried out by comparison of predictions for the forced response of the tuned and mistuned impeller, obtained by means of the ROM and the finite element parent model. Results show that the ROM properly represents the dynamic features of the parent model in the frequency range of interest, with minimal computational cost. Furthermore, the ROM properly captures the localization phenomenon when it occurs.
Impact of the Flow on an Acoustic Excitation System for Aeroelastic Studies
Authors: Freund Oliver , Bartelt Michael , Mittelbach Marc , Montgomery Matthew , Vogt Damian M. , Seume Joerg R. 
Published: December 2013

The flow in turbomachines is highly unsteady. Effects like vortices, flow separation, and shocks are an inevitable part of the turbomachinery flow. Furthermore, high blade aspect ratios, aerodynamically highly loaded and thin profiles increase the blade sensitivity to vibrations. According to the importance of aeroelasticity in turbomachines, new strategies for experimental studies in rotating machines must be developed. A basic requirement for aeroelastic research in rotating machines is to be able to excite the rotor blades in a defined manner.
Approaches for active blade excitation in running machines may be piezoelectric elements, magnetism, or acoustics. Contact-free excitation methods are preferred, since additional mistuning is brought into the investigated system otherwise. A very promising method for aeroelastic research is the non-contact acoustic excitation method.
In this paper investigations on the influence of an annular cascade flow on the blade vibration, excited by an acoustic excitation system, are presented for the first time. These investigations are carried out at the Aeroelastic Test Rig (AETR) of the Royal Institute of Technology in Stockholm. By varying the excitation angle, the outlet Mach number, and the relative position of the excited blade to the excitation system, the influence of the flow on the acoustic excitation is quantified. The results show that there is a strong dependency of the excited vibration amplitude on the excitation angle if the outlet Mach number is increased, which implies that preferable excitation directions exist. Furthermore, it is shown that a benefit up to 23% in terms of excited vibration amplitude can be reached if the flow velocity is raised.
Effects of Stator Flow Distortion on Rotating Blade Endurance: Part 2—Stress Analysis and Failure Criteria
Authors: Simmons Harold , Iyengar Vishwas , Allison Timothy C. 
Published: December 2013

Blade vibrations, with the possibility of failure, is one of the major factors controlling the reliability of compressors and turbines. The prospects of encountering high alternating stress environments in blades make efficient turbomachine operation a very challenging task. In many cases the compressor or turbine functions through a wide range of load, flow, temperature, and speed which affect blade vibration, thus the stress environment continuously changes as the operating conditions changes. Any flow disturbance upstream of the rotating blades and some disturbances downstream will produce repetitive wake pulses that excite the blades. Resonance occurs with any coincidence of repetitive pulses with structural natural frequencies of rotating blades or impellers resulting in substantial amplification of alternating stresses. Most OEM design practices control vibratory stresses by avoiding resonance with expected stator sources; those excitations that cannot be avoided are designed with sufficient endurance to prevent failure. Thus three aspects of rotor/ blade design affect reliability: 1) aerodynamic excitation level and frequency, 2) structural response and resonance margins, and 3) selection and control of materials, coatings and their fabrication process to withstand the service environment. The main objective of this study is to develop a mathematical model to simulate the stresses in the rotating blade row that evaluates all three aspects of design to assess long term endurance.
This is a two part paper on high cycle fatigue (HCF) failure analysis procedure of rotating blades and impellers. Part 1 [1] discusses aerodynamic excitation caused by stator vane and its role in generation of blade vibration. Here comprehensive computational fluid dynamics (CFD) is used to get a better understanding of the stator-rotor flow interactions at different operating conditions. The results of the aerodynamic simulations are order related excitation spectrum that can be applied to the stress/pulsation relationship defined in this part of the paper.
This paper, Part 2, discusses an empirical dynamic stress model developed by impulse testing, assessing material endurance strength, and evaluation of criteria for failure by HCF.
Emergence of Escherichia coli Sequence Type 131 Isolates Producing KPC-2 Carbapenemase in China
Authors: Cai Jia Chang , Zhang Rong , Hu Yan Yan , Zhou Hong Wei , Chen Gong-Xiang 
Published: December 2013

ABSTRACT

Twenty-two KPC-2-producing
Escherichia coli
isolates were obtained from three hospitals in Hangzhou, China, from 2007 to 2011. One isolate, with OmpC porin deficiency, exhibited high-level carbapenem resistance. Pulsed-field gel electrophoresis showed that few isolates were indistinguishable or closely related. Multilocus sequence typing indicated that sequence type 131 (ST131) was the predominant type (9 isolates, 40.9%), followed by ST648 (5 isolates), ST405 (2 isolates), ST38 (2 isolates), and 4 single STs, ST69, ST2003, ST2179, and ST744. Phylogenetic analysis indicated that 9 group B2 isolates belonged to ST131, and 5 of 11 group D isolates belonged to ST648. Only one group B1 isolate and one group A isolate were identified. A representative plasmid (pE1) was partially sequenced, and a 7,788-bp DNA fragment encoding Tn
3
transposase, Tn
3
resolvase, IS
Kpn8
transposase, KPC-2, and IS
Kpn6
-like transposase was obtained. The
bla
KPC-2
-surrounding sequence was amplified by a series of primers. The PCR results showed that 13 isolates were consistent with the genetic environment in pE1. It is the first report of rapid emergence of KPC-2-producing
E. coli
ST131 in China. The
bla
KPC-2
gene of most isolates was located on a similar genetic structure.
Pharmacokinetics of Ertapenem in Critically Ill Patients Receiving Continuous Venovenous Hemodialysis or Hemodiafiltration
Authors: Eyler Rachel F. , Vilay A. Mary , Nader Ahmed M. , Heung Michael , Pleva Melissa , Sowinski Kevin M. , DePestel Daryl D. , Sörgel Fritz , Kinzig Martina , Mueller Bruce A. 
Published: December 2013

ABSTRACT
This study characterizes the pharmacokinetics of ertapenem, a carbapenem antibiotic, in critically ill adult subjects receiving continuous renal replacement therapy (CRRT). Eight critically ill patients with suspected/known Gram-negative infections receiving continuous venovenous hemodialysis (CVVHD) or continuous venovenous hemodiafiltration (CVVHDF) and ertapenem were enrolled. One gram of ertapenem was infused over 30 min. Predialyzer blood samples were drawn with the first dose of ertapenem from the hemodialysis tubing at time zero, 30 min, and 1, 2, 4, 8, 12, 18, and 24 h after the start of the ertapenem infusion. Effluent was collected at the same time points. Ertapenem total serum, unbound serum, and effluent concentrations from all eight subjects were used simultaneously to perform a population compartmental pharmacokinetic modeling procedure using NONMEM. Monte Carlo simulations were performed to evaluate the ability of several ertapenem dosing regimens (500 mg once daily, 750 mg once daily, 500 mg twice daily, and 1,000 mg once daily) to obtain effective unbound serum concentrations above 0.5, 1, and 2 μg/ml. For our simulated patients, all regimens produced unbound ertapenem concentrations above 2 μg/ml for 40% of the dosing interval for at least 96% of simulated patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT00877370.)
Pathogenic Fungus Microsporum canis Activates the NLRP3 Inflammasome
Authors: Mao Liming , Zhang Liping , Li Hua , Chen Wei , Wang Hongbin , Wu Shuxian , Guo Caiqin , Lu Ailing , Yang Guiwen , An Liguo , Abliz Paride , Meng Guangxun 
Published: December 2013

ABSTRACT

Microsporum canis
is a pathogenic fungus with worldwide distribution that causes tinea capitis in animals and humans.
M. canis
also causes invasive infection in immunocompromised patients. To defy pathogenic fungal infection, the host innate immune system is the first line of defense. As an important arm of innate immunity, the inflammasomes are intracellular multiprotein complexes that control the activation of caspase-1, which cleaves proinflammatory cytokine pro-interleukin-1β (IL-1β) into its mature form. To determine whether the inflammasome is involved in the host defense against
M. canis
infection, we challenged human monocytic THP-1 cells and mouse dendritic cells with a clinical strain of
M. canis
isolated from patients with tinea capitis. We found that
M. canis
infection triggered rapid secretion of IL-1β from both THP-1 cells and mouse dendritic cells. Moreover, by using gene-specific shRNA and competitive inhibitors, we determined that
M. canis
-induced IL-1β secretion was dependent on NLRP3. The pathways proposed for NLRP3 inflammasome activation, namely, cathepsin B activity, K
+
efflux, and reactive oxygen species production, were all required for the inflammasome activation triggered by
M. canis
. Meanwhile, Syk, Dectin-1, and Card9 were found to be involved in
M. canis
-induced IL-1β secretion via regulation of pro-IL-1β transcription. More importantly, our data revealed that
M. canis
-induced production of IL-1β was dependent on the NLRP3 inflammasome
in vivo
. Together, this study unveils that the NLRP3 inflammasome exerts a critical role in host innate immune responses against
M. canis
infection, and our data suggest that diseases that result from
M. canis
infection might be controlled by regulating the activation of inflammasomes.
Antibodies to a Single, Conserved Epitope in Anopheles APN1 Inhibit Universal Transmission of Plasmodium falciparum and Plasmodium vivax Malaria
Authors: Armistead Jennifer S. , Morlais Isabelle , Mathias Derrick K. , Jardim Juliette G. , Joy Jaimy , Fridman Arthur , Finnefrock Adam C. , Bagchi Ansu , Plebanski Magdalena , Scorpio Diana G. , Churcher Thomas S. , Borg Natalie A. , Sattabongkot Jetsumon , Dinglasan Rhoel R. 
Published: December 2013

ABSTRACT

Malaria transmission-blocking vaccines (TBVs) represent a promising approach for the elimination and eradication of this disease. AnAPN1 is a lead TBV candidate that targets a surface antigen on the midgut of the obligate vector of the
Plasmodium
parasite, the
Anopheles
mosquito. In this study, we demonstrated that antibodies targeting AnAPN1 block transmission of
Plasmodium falciparum
and
Plasmodium vivax
across distantly related anopheline species in countries to which malaria is endemic. Using a biochemical and immunological approach, we determined that the mechanism of action for this phenomenon stems from antibody recognition of a single protective epitope on AnAPN1, which we found to be immunogenic in murine and nonhuman primate models and highly conserved among anophelines. These data indicate that AnAPN1 meets the established target product profile for TBVs and suggest a potential key role for an AnAPN1-based panmalaria TBV in the effort to eradicate malaria.
Model forIn VivoAssessment of Humoral Protection against Malaria Sporozoite Challenge by Passive Transfer of Monoclonal Antibodies and Immune Serum
Authors: Sack Brandon K. , Miller Jessica L. , Vaughan Ashley M. , Douglass Alyse , Kaushansky Alexis , Mikolajczak Sebastian , Coppi Alida , Gonzalez-Aseguinolaza Gloria , Tsuji Moriya , Zavala Fidel , Sinnis Photini , Kappe Stefan H. I. 
Published: December 2013

ABSTRACTEvidence from clinical trials of malaria vaccine candidates suggests that both cell-mediated and humoral immunity to pre-erythrocytic parasite stages can provide protection against infection. Novel pre-erythrocytic antibody (Ab) targets could be key to improving vaccine formulations, which are currently based on targeting antigens such as the circumsporozoite protein (CSP). However, methods to assess the effects of sporozoite-specific Abs on pre-erythrocytic infectionin vivoremain underdeveloped. Here, we combined passive transfer of monoclonal Abs (MAbs) or immune serum with a luciferase-expressingPlasmodium yoeliisporozoite challenge to assess Ab-mediated inhibition of liver infection in mice. Passive transfer of aP. yoeliiCSP MAb showed inhibition of liver infection when mice were challenged with sporozoites either intravenously or by infectious mosquito bite. However, inhibition was most potent for the mosquito bite challenge, leading to a more significant reduction of liver-stage burden and even a lack of progression to blood-stage parasitemia. This suggests that Abs provide effective protection against a natural infection. Inhibition of liver infection was also achieved by passive transfer of immune serum from whole-parasite-immunized mice. Furthermore, we demonstrated that passive transfer of a MAb againstP. falciparumCSP inhibited liver-stage infection in a humanized mouse/P. falciparumchallenge model. Together, these models constitute unique and sensitivein vivomethods to assess serum-transferable protection againstPlasmodiumsporozoite challenge.
MyD88 Signaling Is Directly Involved in the Development of Murine Placental Malaria
Authors: Barboza Renato , Reis Aramys Silva , da Silva Leandro Gustavo , Hasenkamp Lutero , Pereira Keitty Raquel Benevides , Câmara Niels Olsen Saraiva , Costa Fabio Trindade Maranhão , Lima Maria Regina D'Império , Alvarez José Maria , Boscardin Silvia Beatriz , Epiphanio Sabrina , Marinho Cláudio Romero Farias 
Published: December 2013

ABSTRACT

Malaria is a widespread infectious disease caused by the parasite
Plasmodium
. During pregnancy, malaria infection leads to a range of complications that can affect both the mother and fetus, including stillbirth, infant mortality, and low birth weight. In this study, we utilized a mouse model of placental malaria (PM) infection to determine the importance of the protein MyD88 in the host immune response to
Plasmodium
during pregnancy. Initially, we demonstrated that
Plasmodium berghei
NK65GFP adhered to placental tissue via chondroitin sulfate A and induced PM in mice with a C57BL/6 genetic background. To evaluate the involvement of MyD88 in the pathology of PM, we performed a histopathological analysis of placentas obtained from MyD88
−/−
and wild-type (WT) mice following infection on the 19th gestational day. Our data demonstrated that the detrimental placental alterations observed in the infected mice were correlated with the expression of MyD88. Moreover, in the absence of this protein, production of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) was significantly reduced in the infected mice. More importantly, in contrast to fetuses from infected WT mice, which exhibited a reduction in body weight, the fetuses from infected MyD88
−/−
mice did not display significant weight loss compared to their noninfected littermates. In addition, we observed a decrement of maternal care associated with malaria infection, which was attenuated in the MyD88-deficient mice. Collectively, the results of this study illustrate the pivotal importance of the MyD88 signaling pathway in the pathogenesis of placental malaria, thus presenting new possibilities for targeting MyD88 in therapeutic interventions.
Role of Ferric Reductases in Iron Acquisition and Virulence in the Fungal Pathogen Cryptococcus neoformans
Authors: Saikia Sanjay , Oliveira Debora , Hu Guanggan , Kronstad James 
Published: December 2013

ABSTRACT

Iron acquisition is critical for the ability of the pathogenic yeast
Cryptococcus neoformans
to cause disease in vertebrate hosts. In particular, iron overload exacerbates cryptococcal disease in an animal model, defects in iron acquisition attenuate virulence, and iron availability influences the expression of major virulence factors.
C. neoformans
acquires iron by multiple mechanisms, including a ferroxidase-permease high-affinity system, siderophore uptake, and utilization of both heme and transferrin. In this study, we examined the expression of eight candidate ferric reductase genes and their contributions to iron acquisition as well as to ferric and cupric reductase activities. We found that loss of the
FRE4
gene resulted in a defect in production of the virulence factor melanin and increased susceptibility to azole antifungal drugs. In addition, the
FRE2
gene was important for growth on the iron sources heme and transferrin, which are relevant for proliferation in the host. Fre2 may participate with the ferroxidase Cfo1 of the high-affinity uptake system for growth on heme, because a mutant lacking both genes showed a more pronounced growth defect than the
fre2
single mutant. A role for Fre2 in iron acquisition is consistent with the attenuation of virulence observed for the
fre2
mutant. This mutant also was defective in accumulation in the brains of infected mice, a phenotype previously observed for mutants with defects in high-affinity iron uptake (e.g., the
cfo1
mutant). Overall, this study provides a more detailed view of the iron acquisition components required for
C. neoformans
to cause cryptococcosis.
Mycobacteria and the Greasy Macrophage: Getting Fat and Frustrated
Authors: Neyrolles Olivier 
Published: December 2013

ABSTRACT

In the current issue of
Infection and Immunity
, Caire-Brändli and coworkers (Infect. Immun. 82:476–490, 2014, doi:
10.1128/IAI.01196-13
) describe a novel cell system for studying mycobacterial interactions with foamy macrophages and provide a magnificent series of electron microscopy-based observations providing major insight into the microbiology and cell biology of these interactions.
Oral Immunization with Escherichia coli Expressing a Lipidated Form of LigA Protects Hamsters against Challenge with Leptospira interrogans Serovar Copenhageni
Authors: Lourdault Kristel , Wang Long-Chieh , Vieira Ana , Matsunaga James , Melo Rita , Lewis Michael S. , Haake David A. , Gomes-Solecki Maria 
Published: December 2013

ABSTRACT

Leptospirosis is a potentially fatal zoonosis transmitted by reservoir host animals that harbor leptospires in their renal tubules and shed the bacteria in their urine.
Leptospira interrogans
serovar Copenhageni transmitted from
Rattus norvegicus
to humans is the most prevalent cause of urban leptospirosis. We examined
L. interrogans
LigA, domains 7 to 13 (LigA7-13), as an oral vaccine delivered by
Escherichia coli
as a lipidated, membrane-associated protein. The efficacy of the vaccine was evaluated in a susceptible hamster model in terms of the humoral immune response and survival from leptospiral challenge. Four weeks of oral administration of live
E. coli
expressing LigA7-13 improved survival from intraperitoneal (i.p.) and intradermal (i.d.) challenge by
L. interrogans
serovar Copenhageni strain Fiocruz L1-130 in Golden Syrian hamsters. Immunization with
E. coli
expressing LigA7-13 resulted in a systemic antibody response, and a significant LigA7-13 IgG level after the first 2 weeks of immunization was completely predictive of survival 28 days after challenge. As in previous LigA vaccine studies, all immunized hamsters that survived infection had renal leptospiral colonization and histopathological changes. In summary, an oral LigA-based vaccine improved survival from leptospiral challenge by either the i.p. or i.d. route.