bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three Dimensional Piston Ring-Cylinder Bore Contact Modeling
Authors: Cheng Chao , Kharazmi Ali , Schock Harold , Wineland Richard , Brombolich Larry 
Published: December 2014

Increasing durability, preventing knocking combustion, improving fuel efficiency and reducing pollutant emission characterize the needs for modern internal combustion engine design. These factors are highly influenced by the power cylinder system design. In particular, the piston ring to cylinder bore contact force distribution around the circumference of the piston rings must be optimized under all running conditions. To accomplish this, the ring manufacturers make the ring curvature non-constant along the circumference. Most existing analytical tools are not able to simulate the variation along the ring circumference. In order to improve the understanding of this contact distribution and provide a high-fidelity ring design tool, a three-dimensional finite element piston ring model was developed to accomplish this variation.
The modeling procedure and results are presented in this work. Experiments using a commercially available ring with negative ovality were conducted to validate the model. The ring free shape profile and the ring cross-section geometries were used as inputs to the model. Typical piston ring groove and cylinder wall temperatures were also model inputs to characterize thermal influences on the ring/bore interface forces. The ring/bore conformability was analyzed as a function of the ring radial displacements, cylinder bore constraint forces and thermal load changes to the ring. The model output showed radially separation gaps between the ring front face and the bore. This analysis provides an insight to evaluate the piston ring design. Together with an optimizer, the model can be used as a ring design tool to predict the ring free shape with a specified constraint force distribution pattern. Examples are given to demonstrate the capabilities of this numerical analytical tool. In addition, the 3D ring model can be used to improve the accuracy of existing lubrication, friction and wear analysis tools and therefore improve the entire internal combustion engine power cylinder system design.
Improving the Methodology for 3D Fluid-Thermal Analyses of Large-Bore Engine Cylinder Heads
Authors: Toninel Stefano , Calvert Ian , Phukan Atanu 
Published: December 2014

Efficient use of three-dimensional CFD (Computational Fluid Dynamics) and CHT (Conjugate Heat Transfer) analyses is becoming increasingly critical, in order to compress the development process required for either on-going development, or the design of new large-bore engines for power generation applications.
Engine performance and reliability targets force engine developers to progressively refine and screen design iterations, from the conceptual stage up to the design-freeze, by means of CAE (Computer Aided Engineering) methods, which have to be accurate, robust and cost-effective, in order for them to effectively contribute to the product design. An efficient deployment of these tools usually requires extensive efforts to consolidate the analysis procedures and allow loosening of particular accuracy requirements, in favor of a shorter overall turn-around time. Finally, validation of the models against measurements enables the definition of best-practice guidelines for future programs.
The aim of this paper is to summarize the three-dimensional thermal-fluid simulation methodologies developed in GE’s Distributed Power business, for supporting the design of reciprocating engine cylinder-heads. The work reviews the two main types of analyses which are carried out during the defined development process.
Isothermal simulations are performed in order to estimate the flow-field velocities in the cylinder-head water jacket, without modeling the wall heat-transfer. If backed up by consolidated guidelines, they can be highly efficient for down-selecting design variants, simply by looking at bulk results, with minimum requirements in terms of turbulence modeling.
On the other end of the complexity spectrum, CHT simulations are used to model the thermal behavior of the cylinder-head assembly, by coupling and solving at run-time the RANS (Reynolds Averaged Navier-Stokes) equation set in the fluid domain and Fourier’s equation for the heat-transfer in the solid domain.
The challenging timeline associated to a new engine development program induced the authors to carefully review and adapt, on a case-by-case basis, general CFD best-practice guidelines for near-wall turbulence modeling, well-established in the CFD community. This mitigation was driven by the high complexity of a typical water-jacket geometry and by a number of uncertainties in the real-world application, related to manufacturing tolerances, material properties and operating conditions, which should be considered in order to find the optimal trade-off between absolute accuracy and computational costs.
Verification and validation CHT test-cases were carried out in order to support this approach. In particular, a comparison between the predicted CHT temperature solution and thermocouple measurements, performed on a GE Jenbacher engine, is described, in order to check the effectiveness of the proposed methodology and identifying opportunities for future developments.
Pharmacokinetic-Pharmacodynamic Analysis of Spiroindolone Analogs and KAE609 in a Murine Malaria Model
Authors: Lakshminarayana Suresh B. , Freymond Céline , Fischli Christoph , Yu Jing , Weber Sebastian , Goh Anne , Yeung Bryan K. S. , Ho Paul C. , Dartois Véronique , Diagana Thierry T. , Rottmann Matthias , Blasco Francesca 
Published: December 2014

ABSTRACT

Limited information is available on the pharmacokinetic (PK) and pharmacodynamic (PD) parameters driving the efficacy of antimalarial drugs. Our objective in this study was to determine dose-response relationships of a panel of related spiroindolone analogs and identify the PK-PD index that correlates best with the efficacy of KAE609, a selected class representative. The dose-response efficacy studies were conducted in the
Plasmodium berghei
murine malaria model, and the relationship between dose and efficacy (i.e., reduction in parasitemia) was examined. All spiroindolone analogs studied displayed a maximum reduction in parasitemia, with 90% effective dose (ED
90
) values ranging between 6 and 38 mg/kg of body weight. Further, dose fractionation studies were conducted for KAE609, and the relationship between PK-PD indices and efficacy was analyzed. The PK-PD indices were calculated using the
in vitro
potency against
P. berghei
(2× the 99% inhibitory concentration [IC
99
]) as a threshold (TRE). The percentage of the time in which KAE609 plasma concentrations remained at >2× the IC
99
within 48 h (%
T
>TRE
) and the area under the concentration-time curve from 0 to 48 h (AUC
0–48
)/TRE ratio correlated well with parasite reduction (
R
2
= 0.97 and 0.95, respectively) but less so for the maximum concentration of drug in serum (
C
max
)/TRE ratio (
R
2
= 0.88). The present results suggest that for KAE609 and, supposedly, for its analogs, the dosing regimens covering a
T
>TRE
of 100%, AUC
0–48
/TRE ratio of 587, and a
C
max
/TRE ratio of 30 are likely to result in the maximum reduction in parasitemia in the
P. berghei
malaria mouse model. This information could be used to prioritize analogs within the same class of compounds and contribute to the design of efficacy studies, thereby facilitating early drug discovery and lead optimization programs.
Bacteriophage-Mediated Control of a Two-Species Biofilm Formed by Microorganisms Causing Catheter-Associated Urinary Tract Infections in anIn VitroUrinary Catheter Model
Authors: Lehman Susan M. , Donlan Rodney M. 
Published: December 2014

ABSTRACTMicroorganisms from a patient or their environment may colonize indwelling urinary catheters, forming biofilm communities on catheter surfaces and increasing patient morbidity and mortality. This study investigated the effect of pretreating hydrogel-coated silicone catheters with mixtures ofPseudomonas aeruginosaandProteus mirabilisbacteriophages on the development of single- and two-species biofilms in a multiday continuous-flowin vitromodel using artificial urine. Novel phages were purified from sewage, characterized, and screened for their abilities to reduce biofilm development by clinical isolates of their respective hosts. Our screening data showed that artificial urine medium (AUM) is a valid substitute for human urine for the purpose of evaluating uropathogen biofilm control by these bacteriophages. Defined phage cocktails targetingP. aeruginosaandP. mirabiliswere designed based on the biofilm inhibition screens. Hydrogel-coated catheters were pretreated with one or both cocktails and challenged with approximately 1 × 103CFU/ml of the corresponding pathogen(s). The biofilm growth on the catheter surfaces in AUM was monitored over 72 to 96 h. Phage pretreatment reducedP. aeruginosabiofilm counts by 4 log10CFU/cm2(P≤ 0.01) andP. mirabilisbiofilm counts by >2 log10CFU/cm2(P≤ 0.01) over 48 h. The presence ofP. mirabiliswas always associated with an increase in lumen pH from 7.5 to 9.5 and with eventual blockage of the reactor lines. The results of this study suggest that pretreatment of a hydrogel urinary catheter with a phage cocktail can significantly reduce mixed-species biofilm formation by clinically relevant bacteria.
Mycobacterium abscessus Phospholipase C Expression Is Induced during Coculture within Amoebae and Enhances M. abscessus Virulence in Mice
Authors: Bakala N'Goma Jean Claude , Le Moigne Vincent , Soismier Nathalie , Laencina Laura , Le Chevalier Fabien , Roux Anne-Laure , Poncin Isabelle , Serveau-Avesque Carole , Rottman Martin , Gaillard Jean-Louis , Etienne Gilles , Brosch Roland , Herrmann Jean-Louis , Canaan Stéphane , Girard-Misguich Fabienne 
Published: December 2014

ABSTRACT

Mycobacterium abscessus
is a pathogenic, rapidly growing mycobacterium involved in pulmonary and cutaneo-mucous infections worldwide, to which cystic fibrosis patients are exquisitely susceptible. The analysis of the genome sequence of
M. abscessus
showed that this bacterium is endowed with the metabolic pathways typically found in environmental microorganisms that come into contact with soil, plants, and aquatic environments, where free-living amoebae are frequently present.
M. abscessus
also contains several genes that are characteristically found only in pathogenic bacteria. One of them is
MAB_0555
, encoding a putative phospholipase C (PLC) that is absent from most other rapidly growing mycobacteria, including
Mycobacterium chelonae
and
Mycobacterium smegmatis
. Here, we report that purified recombinant
M. abscessus
PLC is highly cytotoxic to mouse macrophages, presumably due to hydrolysis of membrane phospholipids. We further showed by constructing and using an
M. abscessus
PLC knockout mutant that loss of PLC activity is deleterious to
M. abscessus
intracellular survival in amoebae. The importance of PLC is further supported by the fact that
M. abscessus
PLC was found to be expressed only in amoebae. Aerosol challenge of mice with
M. abscessus
strains that were precultured in amoebae enhanced
M. abscessus
lung infectivity relative to
M. abscessus
grown in broth culture. Our study underlines the importance of PLC for the virulence of
M. abscessus
. Despite the difficulties of isolating
M. abscessus
from environmental sources, our findings suggest that
M. abscessus
has evolved in close contact with environmental protozoa, which supports the argument that amoebae may contribute to the virulence of opportunistic mycobacteria.
Genetic Analysis Reveals the Identity of the Photoreceptor for Phototaxis in Hormogonium Filaments of Nostoc punctiforme
Authors: Campbell Elsie L. , Hagen Kari D. , Chen Rui , Risser Douglas D. , Ferreira Daniela P. , Meeks John C. 
Published: December 2014

ABSTRACT

In cyanobacterial
Nostoc
species, substratum-dependent gliding motility is confined to specialized nongrowing filaments called hormogonia, which differentiate from vegetative filaments as part of a conditional life cycle and function as dispersal units. Here we confirm that
Nostoc punctiforme
hormogonia are positively phototactic to white light over a wide range of intensities.
N. punctiforme
contains two gene clusters (clusters 2 and 2i), each of which encodes modular cyanobacteriochrome–methyl-accepting chemotaxis proteins (MCPs) and other proteins that putatively constitute a basic chemotaxis-like signal transduction complex. Transcriptional analysis established that all genes in clusters 2 and 2i, plus two additional clusters (clusters 1 and 3) with genes encoding MCPs lacking cyanobacteriochrome sensory domains, are upregulated during the differentiation of hormogonia. Mutational analysis determined that only genes in cluster 2i are essential for positive phototaxis in
N. punctiforme
hormogonia; here these genes are designated
ptx
(for
p
hoto
t
a
x
is) genes. The cluster is unusual in containing complete or partial duplicates of genes encoding proteins homologous to the well-described chemotaxis elements CheY, CheW, MCP, and CheA. The cyanobacteriochrome-MCP gene (
ptxD
) lacks transmembrane domains and has 7 potential binding sites for bilins. The transcriptional start site of the
ptx
genes does not resemble a sigma 70 consensus recognition sequence; moreover, it is upstream of two genes encoding gas vesicle proteins (
gvpA
and
gvpC
), which also are expressed only in the hormogonium filaments of
N. punctiforme
.
Mep72, a Metzincin Protease That Is Preferentially Secreted by Biofilms of Pseudomonas aeruginosa
Authors: Passmore Ian J. , Nishikawa Kahoko , Lilley Kathryn S. , Bowden Steven D. , Chung Jade C. S. , Welch Martin 
Published: December 2014

ABSTRACT

In this work, we compared the profile of proteins secreted by planktonic and biofilm cultures of
Pseudomonas aeruginosa
using two-dimensional difference gel electrophoresis (2D-DiGE). This revealed that a novel metzincin protease, Mep72, was secreted during biofilm growth. Subsequent Western blotting and reverse transcription-PCR (RT-PCR) analyses demonstrated that Mep72 was expressed only during biofilm growth. Mep72 has a tridomain structure comprised of a metzincin protease-like domain and two tandem carbohydrate-binding domains. Unlike the only other metzincin (alkaline protease; AprA) in
P. aeruginosa
, Mep72 is secreted through the type II pathway and undergoes processing during export. During this processing, the metzincin domain is liberated from the carbohydrate-binding domains. This processing may be self-catalyzed, since purified Mep72 autodegraded
in vitro
. This autodegradation was retarded in the presence of alginate (an extracellular matrix component of many
P. aeruginosa
biofilms). The expression of full-length
mep72
in
Escherichia coli
was toxic. However, this toxicity could be alleviated by coexpression of
mep72
with the adjacent gene,
bamI
. Mep72 and BamI were found to form a protein-protein complex
in vitro
. 2D-DiGE revealed that the electrophoretic mobility of several discrete protein spots was altered in the biofilm secretome of an
mep72
mutant, including type III secretion proteins (PopD, PcrV, and ExoS) and a flagellum-associated protein (FliD). Mep72 was found to bind directly to ExoS and PcrV and to affect the processing of these proteins in the biofilm secretome. We conclude that Mep72 is a secreted biofilm-specific regulator that affects the processing of a very specific subset of virulence factors.
Bacteria in Solitary Confinement
Authors: Mullineaux Conrad W. 
Published: December 2014

ABSTRACT

Even in clonal bacterial cultures, individual bacteria can show substantial stochastic variation, leading to pitfalls in the interpretation of data derived from millions of cells in a culture. In this issue of the
Journal of Bacteriology
, as part of their study on osmoadaptation in a cyanobacterium, Nanatani et al. describe employing an ingenious microfluidic device that gently cages individual cells (J Bacteriol 197:676–687, 2015,
http://dx.doi.org/10.1128/JB.02276-14
). The device is a welcome addition to the toolkit available to probe the responses of individual cells to environmental cues.
Prevalence of risk factors for coronary artery disease in an urban Indian population
Authors: Sekhri T , Kanwar R S , Wilfred R , Chugh P , Chhillar M , Aggarwal R , Sharma Y K , Sethi J , Sundriyal J , Bhadra K , Singh S , Rautela N , Chand Tek , Singh M , Singh S K 
Published: December 2014

ObjectiveThe objective of this study was to assess the prevalence of risk factors for coronary artery disease (CAD) in government employees across India.MethodsThe study population consisted of government employees in different parts of India ({n=10 642 men and n=1966 women; age 20–60 years}) and comprised various ethnic groups living in different environmental conditions. Recruitment was carried out in 20 cities across 14 states, and in one union territory. All selected individuals were subjected to a detailed questionnaire, medical examinations and anthropometric measurements. Blood samples were collected for blood glucose and serum lipid profile estimation, and resting ECG was recorded. Results were analysed using appropriate statistical tools.ResultsThe study revealed that 4.6% of the study population had a family history of premature CAD. The overall prevalence of diabetes was 16% (5.6% diagnosed during the study and the remaining 10.4% already on medication). Hypertension was present in 21% of subjects. The prevalence of dyslipidemia was significantly high, with 45.6% of study subjects having a high total cholesterol/high density lipoprotein ratio. Overall, 78.6% subjects had two or more risk factors for CAD.ConclusionsThe present study demonstrates a high prevalence of CAD risk factors in the Indian urban population. Therefore, there is an immediate need to initiate measures to raise awareness of these risk factors so that individuals at high risk for future CAD can be managed.
Exposure to genocide and risk of suicide in Rwanda: a population-based case–control study
Authors: Rubanzana Wilson , Hedt-Gauthier Bethany L , Ntaganira Joseph , Freeman Michael D 
Published: December 2014

BackgroundIn Rwanda, an estimated one million people were killed during the 1994 genocide, leaving the country shattered and social fabric destroyed. Large-scale traumatic events such as wars and genocides have been linked to endemic post-traumatic stress disorder, depression and suicidality. The study objective was to investigate whether the 1994 genocide exposure is associated with suicide in Rwanda.MethodsWe conducted a population-based case–control study. Suicide victims were matched to three living controls for sex, age and residential location. Exposure was defined as being a genocide survivor, having suffered physical/sexual abuse in the genocide, losing a first-degree relative in the genocide, having been convicted for genocide crimes or having a first-degree relative convicted for genocide. From May 2011 to May 2013, 162 cases and 486 controls were enrolled countrywide. Information was collected from the police, local village administrators and family members.ResultsAfter adjusting for potential confounders, having been convicted for genocide crimes was a significant predictor for suicide (OR=17.3, 95% CI 3.4 to 88.1). Being a survivor, having been physically or sexually abused during the genocide, and having lost a first-degree family member to genocide were not significantly associated with suicide.ConclusionsThese findings demonstrate that individuals convicted for genocide crimes are experiencing continued psychological disturbances that affect their social reintegration into the community even 20 years after the event. Given the large number of genocide perpetrators reintegrated after criminal courts and Gacaca traditional reconciling trials, suicide could become a serious public health burden if preventive remedial action is not identified.
Sedimentary development and magnetic susceptibility evolution of the Frasnian in Western Belgium (Dinant Synclinorium, La Thure section)
Authors: Pas D. , Da Silva A. C. , Devleeschouwer X. , De Vleeschouwer D. , Labaye C. , Cornet P. , Michel J. , Boulvain F. 
Published: December 2014

Abstract

Recent opening of the La Thure quarry in Western Belgium allowed the collection of new data from a poorly outcropping area of the Belgian Frasnian platform. The studied section covers an interval extending from the
falsiovalis
to
hassi
s.l. Zones. Sedimentological analyses allowed the reconstruction of depositional settings in the northwestern part of the Dinant Synclinorium after the demise of the extended Givetian carbonate platform. Two depositional models are distinguished: (a) siliciclastic drowned platform during the Early Frasnian; and (b) a fore-reef depositional setting belonging to a rimmed shelf during the Middle Frasnian. Moreover, interpreted depositional settings in the northwestern part of the Dinant Synclinorium allowed to constraint the direction of the main facies belts for the Belgian Frasnian platform. Combination of MS and geochemistry demonstrates the inherent-parallel link existing between variation in MS values and proxy for terrestrial input (such as Si and Al). This observation means that, despite the remagnetization occurring within the Belgian Frasnian lithologies, the main trends in the MS signal from the La Thure section still reflect some syn-sedimentary conditions. The increase in MS and clastic input proxies recorded in distal fore-reef deposit within the
punctata
Zone are likely to be considered as enhanced by rapid and strong shallowing events recognized in the ‘
puncata
Event’ interval.
Gas-driven radionuclide transport in undisturbed and disturbed Boom Clay
Authors: Jacops E. , Maes T. , Maes N. , Volckaert G. , Weetjens E. , Sillen X. 
Published: December 2014

Abstract
In deep geological repositories for the disposal of radioactive waste, gas can be generated by different mechanisms including anaerobic corrosion, radiolysis and microbial degradation. If the gas generation rate is larger than the capacity for the diffusive transport of the dissolved gas, a free gas phase will be formed, eventually leading to gas-breakthrough events. Depending on the timing of gas breakthrough, dissolved radionuclides (RN) and contaminants could be driven out of the clay faster than the normally expected diffusive transport.

A column experiment was designed in which a water-saturated clay core is placed directly on top of a thin Boom Clay core that has been previously saturated with a tracer solution (0.01 mol l
−1
NaI). A helium gas pressure is applied and stepwise increased. Upon gas breakthrough, the water on top of the column is expelled and analysed for its iodide content. The measured concentration iodide is linked to the amount of NaI-saturated pore water that was displaced.

Based on the results, it can be concluded that the transport of radionuclides and contaminants because of a gas-breakthrough event is possible but appears to be very limited. The volume of water displaced is very low (three orders of magnitude) compared to the volume of gas transported upon breakthrough.