bluuebunny/crossref_metadata_2025_split huggingface dataset:
Limits for NOx Reduction by EGR in a Heavy Duty Diesel Engine at Stationary and Transient Conditions
Authors: Schalk Erwin , Ofner Herwig , Doppler Christian , Daum Steffen , Danninger Alois , Schutting Eberhard , Kislinger Peter 
Published: July 2013

Exhaust gas recirculation (EGR) is an effective engine internal measure to reduce NOx emissions. This is e.g. constituted by the fact that the NOx limit of the current European on-road emission regulation EURO V can be met exclusively by the application of EGR (an overview on emissions regulations is e.g. given in [1]). However, the proposed NOx limits for the upcoming regulations have been lowered significantly which implicates much higher EGR rates compared to the EURO V applications if this strategy is further pursued. This is valid for both the future on-road regulation (EURO VI) and the off-road regulation (Stage IV). In this paper main focus is laid on off-road applications.
One of the main challenges of this task refers to transient engine operation which also requires EGR. Thus, great demands are made to the design and calibration of the charging system in order to guarantee acceptable load response characteristics during the acceleration phases.
An experimental study was carried out with a modified EURO V heavy duty engine which was operated in an engine test cell under stationary and transient conditions with various engine settings. These primarily referred to the EGR rate and smoke limitations during transient operation. In this way the NOx, soot and load response characteristics were systematically investigated. With the used test engine the NOx emissions could not be lowered below a level of approximately 0.6 g/kWh in the Non-Road Transient Test Cycle (NRTC) [1] without a significant deterioration in load response (for comparison — the proposed Stage IV NOx limit is 0.4 g/kWh in the NRTC).
3D Model Construction of Cutting Tools and Identification of Workpieces Using Machine Vision for Virtual Machining Simulation
Authors: Nishiyama Mamoru , Sato Ryuta , Shirase Keiichi 
Published: July 2013

In virtual machining simulation to verify NC programs for machining operation, construction of 3D (three-dimensional) models of cutting tools to be used and identification of posture and position of workpiece to be machined are quite important to achieve reliable verification.
Especially, a 3D model construction of cutting tools requires skill-full operations and it takes much time and cost. Several geometric parameters to define cutting tool shapes are needed to construct precise 3D models for virtual machining simulation. Even though, careless mistake to set parameters of tool diameter and length causes machining troubles. Therefore, no trouble was happened in virtual machining simulation, it is still required to check machining troubles through the trial-cutting on actual NC machine tools.
In this paper, new methods to construct 3D models of cutting tools and identification of posture and position of workpiece are proposed. Experimental measurement of cutting tool shape is performed on the machine tool using a CCD camera, and a 3D model of cutting tool was constructed successfully. By this method, setting of invalid parameters to define cutting tool shapes can be avoided.
Also, posture and position of the workpiece can be identified successfully. These parameters can be used to detect wrong setup operation before actual machining operation.
Bimorph Piezoelectric Cymbal Design in Energy Harvesting
Authors: Mo Changki , Jordan Steve , Clark William W. 
Published: July 2013

This paper presents the development of a bimorph piezoelectric cymbal energy harvester that is particularly useful for extracting energy from the vibrating systems of relatively high compressive load. The bimorph cymbal harvester can be used to charge a capacitor or a battery through the piezoelectric layers fitted within the metal end caps under repeated compression or deformation.
In this work, feasibility of a bimorph piezoelectric cymbal harvester in series operation is investigated through theoretical analysis and experimental validation. The bimorph cymbal uses a composite disc of two piezoelectric layers and a steel substrate between metal end caps.
Theoretical modeling to quantify the generated energy by using bimorph cymbal design is first conducted. A parametric study is then performed to optimize generated energy with the dominant design parameters influencing energy harvesting performance for the cymbal structure. The parameters such as thickness of the end caps, radius ratio of the apex to the cavity of the end caps, cavity depth, and thickness ratio of the piezoelectric to the steel substrate are considered. Based on the optimized dimension, a cymbal harvester was fabricated and tested to validate analytically predicted open-circuit voltage on a hand jack type test rig.
Experimental result indicates that the measured open-circuit voltage from the bimorph cymbal harvester is less than that of analytically predicted. However, it shows that the bimorph piezoelectric cymbal structure is an alternative cymbal design that is useful for harvesting energy from the source of relatively high load.
Cooling Strategies for a SMA Wire Actuator in a Feed Axis
Authors: Meier Horst , Pollmann Jan , Czechowicz Alexander 
Published: July 2013

Shape memory alloys (SMA) are smart materials which can be activated thermally. They are suitable for the use as actuators due to their ability to remember an imprinted shape through thermal activation. In addition, actuators based on shape memory alloys offer a higher work output in relation to their volume compared to other actuator concepts. Other advantages of using SMA in actuation applications include the ability to design lightweight systems and the comparatively low material costs.
On the other hand, designing an SMA actuator poses a challenge in case a specific rate of feed has to be achieved. These difficulties become especially apparent if the actuator is used to create a defined displacement not only in its activation direction, but in the returning (deactivation) direction as well. This might occur, for example, while devising an SMA-driven feed axis.
During the activation of the SMA, the speed of the actuator and therefore the speed of the axis can be influenced by choosing a specific thermal energy transfer method. For instance, when using the intrinsic resistance for heating purposes, the speed can be controlled by changing the electrical current running through the SMA. However, after the deactivation (end of the heating phase) of the shape memory alloy, the transformation needs a considerably longer time. For an exemplary SMA wire actuator, the transformation time in room temperature can be five times higher than the activation time. For usage in a feed axis, the actuator should produce similar speeds in both the activation and deactivation direction.
To achieve this, different strategies for cooling the SMA after cutting off the current are investigated. These strategies include an active air cooling system with different flow characteristics and the operation of the actuator in a cooling fluid.
In a nutshell, the paper compares different ways of cooling an SMA wire actuator to increase the transformation speed after deactivation. The aim is to make the deactivation speed as manageable as the activation speed.
Dual Mode Sensing of Crack Growth in Steel Bridge Structures
Authors: Yu Lingyu , Zhao Liuxian , Tian Zhenhua , Giurgiutiu Victor , Ziehl Paul 
Published: July 2013

Monitoring of fatigue cracking in steel bridge structures using a combined passive and active scheme has been approached by the authors. Passive acoustic emission (AE) monitoring is able to detect crack growth behavior by picking up the stress waves resulting from the breathing of cracks while active ultrasonic pulsing can quantitatively assess structural defect by sensing out an interrogating pulse and receiving the structural reflections. The dual-mode sensing functionality is pursued by using the R15I ultrasonic transducers.
In the paper, we presented the subject dual-mode sensing on steel compact tension (CT) specimens in a laboratory setup. Passive AE sensing was performed during fatigue loading and showed its capability to detect crack growth and location. At selected intervals of loading cycles, the test was paused to allow for active sensing by pulsing the transducers in a round-robin pattern. Plate waves were excited, propagated and interacted within the structure. Several approaches were proposed to analyze the interrogation data and to correlate the data features with crack growth. Root means square deviation (RMSD) damage index (DI) was found as a good indicator for indicating the overall crack development. Short time Fourier transform (STFT) provided both time and frequency information at the same time. Moreover, wave velocity analysis showed interesting results when crack developed across the transmitter-receiver path.
Detection of Botulinum Neurotoxin/A Insertion Using an Encapsulated Interface Bilayer
Authors: Taylor Graham , Leo Donald , Sarles Andy 
Published: July 2013

Many signaling mechanisms in living cells occur at biological boundaries via cell surface receptors and membrane proteins embedded in lipid bilayers. The coordination of actions of sensory and motor neurons in the nervous system represents one example of many that heavily depends on lipid membrane bound receptor mediated signaling. As a result, chemical and biological toxins that disrupt these neural signals can have severe physiological effects, including paralysis and death. Botulinum neurotoxin Type A (BoNT/A) is a proteolytic toxin that inserts through vesicle membranes and cleaves membrane receptors involved with synaptic acetylcholine uptake and nervous system signal conduction.
In this work, we investigate the use of a Bioinspired liquid-supported interface bilayer for studying the insertion of BoNT/A toxin molecules into synthetic lipid bilayers. DPhPC lipid bilayers are formed using the regulated attachment method (RAM), as developed by Sarles and Leo, and we perform current measurements on membranes exposed to BoNT/A toxin to characterize activity of toxin interacting with the synthetic bilayer. Control tests without toxin present are also presented. The results of these tests show an increase in the magnitude of current through the bilayer when the toxin is included. We interpret these initial results to mean that incorporation of BoNT/A toxin at a high concentration in an interface bilayer increases the permeability of the membrane as a result of toxin molecules spanning the thickness of the bilayer.
EsiB, a Novel Pathogenic Escherichia coli Secretory Immunoglobulin A-Binding Protein Impairing Neutrophil Activation
Authors: Pastorello Ilaria , Rossi Paccani Silvia , Rosini Roberto , Mattera Rossella , Ferrer Navarro Mario , Urosev Dunja , Nesta Barbara , Lo Surdo Paola , Del Vecchio Mariangela , Rippa Valentina , Bertoldi Isabella , Gomes Moriel Danilo , Laarman Alexander J. , van Strijp Jos A. G. , Daura Xavier , Pizza Mariagrazia , Serino Laura , Soriani Marco 
Published: July 2013

ABSTRACT

In this study, we have characterized the functional properties of a novel
Escherichia coli
antigen named EsiB (

E
. coli

s
ecretory
i
mmunoglobulin A-
b
inding protein), recently reported to protect mice from sepsis. Gene distribution analysis of a panel of 267 strains representative of different
E. coli
pathotypes revealed that
esiB
is preferentially associated with extraintestinal strains, while the gene is rarely found in either intestinal or nonpathogenic strains. These findings were supported by the presence of anti-EsiB antibodies in the sera of patients affected by urinary tract infections (UTIs). By solving its crystal structure, we observed that EsiB adopts a superhelical fold composed of Sel1-like repeats (SLRs), a feature often associated with bacterial proteins possessing immunomodulatory functions. Indeed, we found that EsiB interacts with secretory immunoglobulin A (SIgA) through a specific motif identified by an immunocapturing approach. Functional assays showed that EsiB binding to SIgA is likely to interfere with productive FcαRI signaling, by inhibiting both SIgA-induced neutrophil chemotaxis and respiratory burst. Indeed, EsiB hampers SIgA-mediated signaling events by reducing the phosphorylation status of key signal-transducer cytosolic proteins, including mitogen-activated kinases. We propose that the interference with such immune events could contribute to the capacity of the bacterium to avoid clearance by neutrophils, as well as reducing the recruitment of immune cells to the infection site.

IMPORTANCE
Pathogenic
Escherichia coli
infections have recently been exacerbated by increasing antibiotic resistance and the number of recurrent contagions. Attempts to develop preventive strategies against
E. coli
have not been successful, mainly due to the large antigenic and genetic variability of virulence factors, but also due to the complexity of the mechanisms used by the pathogen to evade the immune system. In this work, we elucidated the function of a recently discovered protective antigen, named EsiB, and described its capacity to interact with secretory immunoglobulin A (SIgA) and impair effector functions. This work unravels a novel strategy used by
E. coli
to subvert the host immune response and avoid neutrophil-dependent clearance.
Clinically Relevant Mutant DNA Gyrase Alters Supercoiling, Changes the Transcriptome, and Confers Multidrug Resistance
Authors: Webber Mark A. , Ricci Vito , Whitehead Rebekah , Patel Meha , Fookes Maria , Ivens Alasdair , Piddock Laura J. V. 
Published: July 2013

ABSTRACT

Bacterial DNA is maintained in a supercoiled state controlled by the action of topoisomerases. Alterations in supercoiling affect fundamental cellular processes, including transcription. Here, we show that substitution at position 87 of GyrA of
Salmonella
influences sensitivity to antibiotics, including nonquinolone drugs, alters global supercoiling, and results in an altered transcriptome with increased expression of stress response pathways. Decreased susceptibility to multiple antibiotics seen with a GyrA Asp87Gly mutant was not a result of increased efflux activity or reduced reactive-oxygen production. These data show that a frequently observed and clinically relevant substitution within GyrA results in altered expression of numerous genes, including those important in bacterial survival of stress, suggesting that GyrA mutants may have a selective advantage under specific conditions. Our findings help contextualize the high rate of quinolone resistance in pathogenic strains of bacteria and may partly explain why such mutant strains are evolutionarily successful.

IMPORTANCE
Fluoroquinolones are a powerful group of antibiotics that target bacterial enzymes involved in helping bacteria maintain the conformation of their chromosome. Mutations in the target enzymes allow bacteria to become resistant to these antibiotics, and fluoroquinolone resistance is common. We show here that these mutations also provide protection against a broad range of other antimicrobials by triggering a defensive stress response in the cell. This work suggests that fluoroquinolone resistance mutations may be beneficial under a range of conditions.
Interkingdom Signaling Induces Streptococcus pneumoniae Biofilm Dispersion and Transition from Asymptomatic Colonization to Disease
Authors: Marks Laura R. , Davidson Bruce A. , Knight Paul R. , Hakansson Anders P. 
Published: July 2013

ABSTRACTStreptococcus pneumoniaeis a common human nasopharyngeal commensal colonizing 10% to 40% of healthy individuals, depending on age. Despite a low invasive disease rate, widespread carriage ensures that infection occurs often enough to makeS. pneumoniaea leading bacterial cause of respiratory disease worldwide. However, the mechanisms behind transition from asymptomatic colonization to dissemination and disease in otherwise sterile sites remain poorly understood but are epidemiologically strongly linked to infection with respiratory viruses. In this report, we show that infection with influenza A virus and treatment with the resulting host signals (febrile-range temperatures, norepinephrine, extracytoplasmic ATP, and increased nutrient availability) induce the release of bacteria from biofilms in a newly developed biofilm model on live epithelial cells bothin vitroand duringin vivocolonization. These dispersed bacteria have distinct phenotypic properties different from those of both biofilm and broth-grown, planktonic bacteria, with the dispersed population showing differential virulence gene expression characteristics resulting in a significantly increased ability to disseminate and cause infection of otherwise sterile sites, such as the middle ear, lungs, and bloodstream. The results offer novel and important insights into the role of interkingdom signaling between microbe and host during biofilm dispersion and transition to acute disease.IMPORTANCEThis report addresses the mechanisms involved in transition from pneumococcal asymptomatic colonization to disease. In this study, we determined that changes in the nasopharyngeal environment result in the release of bacteria from colonizing biofilms with a gene expression and virulence phenotype different not only from that of colonizing biofilm bacteria but also from that of the broth-grown planktonic bacteria commonly used for pathogenesis studies. The work importantly also identifies specific host factors responsible for the release of bacteria and their changed phenotype. We show that these interkingdom signals are recognized by bacteria and are induced by influenza virus infection, which is epidemiologically strongly associated with transition to secondary pneumococcal disease. As virus infection is a common inducer of transition to disease among species occupying the nasopharynx, the results of this study may provide a basis for better understanding of the signals involved in the transition from colonization to disease in the human nasopharynx.
Receptor Polymorphism Restricts Contact-Dependent Growth Inhibition to Members of the Same Species
Authors: Ruhe Zachary C. , Wallace Adam B. , Low David A. , Hayes Christopher S. 
Published: July 2013

ABSTRACT

Bacteria that express contact-dependent growth inhibition (CDI) systems outcompete siblings that lack immunity, suggesting that CDI mediates intercellular competition. To further explore the role of CDI in competition, we determined the target cell range of the CDI
EC93
system from
Escherichia coli
EC93. The CdiA
EC93
effector protein recognizes the widely conserved BamA protein as a receptor, yet
E. coli
EC93 does not inhibit other enterobacterial species. The predicted membrane topology of BamA indicates that three of its extracellular loops vary considerably between species, suggesting that loop heterogeneity may control CDI specificity. Consistent with this hypothesis, other enterobacteria are sensitized to CDI
EC93
upon the expression of
E
.
coli bamA
and
E. coli
cells become CDI
EC93
resistant when
bamA
is replaced with alleles from other species. Our data indicate that BamA loops 6 and 7 form the CdiA
EC93
-binding epitope and their variation between species restricts CDI
EC93
target cell selection. Although BamA loops 6 and 7 vary dramatically between species, these regions are identical in hundreds of
E. coli
strains, suggesting that BamA
Ecoli
and CdiA
EC93
play a role in self-nonself discrimination.

IMPORTANCE
Contact-dependent growth inhibition (CDI) systems are widespread among Gram-negative bacteria, enabling them to bind to neighboring bacterial cells and deliver protein toxins that inhibit cell growth. In this study, we tested the role of CDI in interspecies competition using intestinal isolate
Escherichia coli
EC93 as an inhibitor cell model. Although
E. coli
EC93 inhibits different
E. coli
strains, other bacterial species from the intestine are completely resistant to CDI. We show that resistance is due to small variations in the CDI receptor that prevent other species from being recognized as target cells. CDI receptor interactions thus provide a mechanism by which bacteria can distinguish siblings and other close relatives (self) from more distant relatives or other species of bacteria (nonself). Our results provide a possible means by which antimicrobials could be directed to one or only a few related bacterial pathogens by using a specific receptor “zip code.”
Practical responses to confidentiality dilemmas in elite sport medicine
Authors: Malcolm Dominic , Scott Andrea 
Published: July 2013

AimTo examine the ethical challenges of upholding patient confidentiality in sports medicine and the practical responses of clinicians to these challenges.MethodQuestionnaire survey and follow-up semi-structured interviews with the members of the British Olympic Association's Medical Committee and Physiotherapy Forum.ResultsClinicians identified three contextual factors that influenced issues related to patient confidentiality in sports medicine: the use of confidentiality waivers; the facilities available for treatment; and the cultural norms of elite sport. They further identified interpersonal strategies used to lessen or eradicate conflicts, including emphasising the benefits and avoidance of disbenefits for athletes and the potential negative consequences for others.ConclusionsAspects of clinicians’ practice environment should be designed to enable compliance with the highest levels of ethical conduct. Professional associations should establish guidelines for clinicians’ interpersonal conduct in dealing with confidentiality issues and consider their provision of ethics-based continuous professional development. They should also petition for the establishment of athletes’ codes of conduct which identify a context-relevant understanding of ‘serious harm’ and how that might impact on information disclosure.
HIV enteropathy: HAART reduces HIV-induced stem cell hyperproliferation and crypt hypertrophy to normal in jejunal mucosa
Authors: Batman Philip A , Kapembwa Moses S , Belmonte Liliana , Tudor Gregory , Kotler Donald P , Potten Christopher S , Booth Catherine , Cahn Pedro , Griffin George E 
Published: July 2013

ObjectiveTo analyse the structural and kinetic response of small intestinal crypt epithelial cells including stem cells to highly active antiretroviral therapy (HAART).DesignCrypt size and proliferative activity of transit and stem cells in jejunal mucosa were quantified using morphometric techniques.MethodsCrypt length was measured by counting the number of enterocytes along one side of a number of crypts in each biopsy specimen and the mean crypt length was calculated. Proliferating crypt cells were identified with MIB-1 monoclonal antibody, and the percentage of crypt cells in proliferation was calculated at each cell position along the length of the crypt (proliferation index). Data were obtained from 9 HIV-positive test patients co-infected with microsporidia, 34 HIV-positive patients receiving HAART and 13 control cases.ResultsCrypt length was significantly greater in test patients than in controls, but crypt length in patients receiving HAART was normal. The proliferation index was greater in test subjects than in controls in stem and transit cell compartments, and was decreased in patients treated with HAART only in the stem cell region of the crypt.ConclusionsVillous atrophy in HIV enteropathy is attributed to crypt hypertrophy and encroachment of crypt cells onto villi. HAART restores normal crypt structure by inhibition of HIV-driven stem cell hyperproliferation at the crypt bases.