bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecology and status of the jaguarundi Puma yagouaroundi: a synthesis of existing knowledge
Authors: Giordano Anthony J.
Published: November 2015

The ecology of the jaguarundi is poorly known, so I reviewed the literature for all original data and remarks on jaguarundi observations, ecology, and behaviour, to synthesize what is known about the species.

Jaguarundis occupy and use a range of habitats with dense undergrowth from northern Mexico to central Argentina, but may be most abundant in seasonal dry, Atlantic, gallery, and mixed grassland/agricultural forest landscapes.

Jaguarundis are principally predators of small (sigmodontine) rodents, although other mammals, birds, and squamate reptiles are taken regularly.

The vast majority of jaguarundi camera‐trap records occurred during daylight hours (0600 h–1800 h); jaguaurndis are also predominantly terrestrial, although they appear to be capable tree climbers.

Home range sizes for jaguarundis vary greatly, but most are ≤25 km2; females' territories may be much smaller than or similar in size to those of males. Males may concentrate movements in one area before shifting to another and, as with other felids, intersexual overlap in habitat use appears to be common.

Interference competition may be important in influencing the distribution and ecology of jaguarundis, although their diurnal habits may somewhat mitigate its effect.

Conflict between humans and jaguarundis over small livestock may be widespread among rural human communities and is likely to be underreported. Despite this conflict, jaguarundis can persist in agriculturally modified landscapes and small forest fragments.

Additional research on local jaguarundi populations from more areas should be a priority to determine the true status of the species.
Characterization of Plasmodium phosphatidylserine decarboxylase expressed in yeast and application for inhibitor screening
Authors: Choi Jae‐Yeon , Kumar Vidya , Pachikara Niseema , Garg Aprajita , Lawres Lauren , Toh Justin Y. , Voelker Dennis R. , Ben Mamoun Choukri
Published: November 2015

Phospholipid biosynthesis is critical for the development, differentiation and pathogenesis of several eukaryotic pathogens. Genetic studies have validated the pathway for phosphatidylethanolamine synthesis from phosphatidylserine catalyzed by phosphatidylserine decarboxylase enzymes (PSD) as a suitable target for development of antimicrobials; however no inhibitors of this class of enzymes have been discovered. We show that the Plasmodium falciparum PSD can restore the essential function of the yeast gene in strains requiring PSD for growth. Genetic, biochemical and metabolic analyses demonstrate that amino acids between positions 40 and 70 of the parasite enzyme are critical for proenzyme processing and decarboxylase activity. We used the essential role of Plasmodium PSD in yeast as a tool for screening a library of anti‐malarials. One of these compounds is 7‐chloro‐N‐(4‐ethoxyphenyl)‐4‐quinolinamine, an inhibitor with potent activity against P. falciparum, and low toxicity toward mammalian cells. We synthesized an analog of this compound and showed that it inhibits PfPSD activity and eliminates Plasmodium yoelii infection in mice. These results highlight the importance of 4‐quinolinamines as a novel class of drugs targeting membrane biogenesis via inhibition of PSD activity
Cyclic‐di‐AMPsynthesis by the diadenylate cyclaseCdaAis modulated by the peptidoglycan biosynthesis enzymeGlmMinLactococcus lactis
Authors: Zhu Yan , Pham Thi Huong , Nhiep Thi Hanh Nguyen , Vu Ngoc Minh Thu , Marcellin Esteban , Chakrabortti Alolika , Wang Yuanliang , Waanders Jennifer , Lo Raquel , Huston Wilhelmina M. , Bansal Nidhi , Nielsen Lars K. , Liang Zhao‐Xun , Turner Mark S.
Published: November 2015

The second messenger cyclic‐di‐adenosine monophosphate (c‐di‐AMP) plays important roles in growth, virulence, cell wall homeostasis, potassium transport and affects resistance to antibiotics, heat and osmotic stress. MostFirmicutes contain only one c‐di‐AMPsynthesizing diadenylate cyclase (CdaA); however, little is known about signals and effectors controllingCdaAactivity and c‐di‐AMPlevels. In this study, a genetic screen was employed to identify components which affect the c‐di‐AMPlevel inLactococcus. We characterized suppressor mutations that restored osmoresistance to spontaneous c‐di‐AMPphosphodiesterasegdpPmutants, which contain high c‐di‐AMPlevels. Loss‐of‐function and gain‐of‐function mutations were identified in thecdaAandgdpPgenes, respectively, which led to lower c‐di‐AMPlevels. A mutation was also identified in the phosphoglucosamine mutase geneglmM, which is commonly located within thecdaAoperon in bacteria. TheglmMI154F mutation resulted in a lowering of the c‐di‐AMPlevel and a reduction in the key peptidoglycan precursorUDP‐N‐acetylglucosamine inL.lactis. C‐di‐AMPsynthesis byCdaAwas shown to be inhibited by GlmMI154Fmore thanGlmMand GlmMI154Fwas found to bind more strongly toCdaAthanGlmM. These findings identifyGlmMas a c‐di‐AMPlevel modulating protein and provide a direct connection between c‐di‐AMPsynthesis and peptidoglycan biosynthesis.
Insights into the smooth‐to‐rough transitioning in Mycobacterium bolletii unravels a functional Tyr residue conserved in all mycobacterial MmpL family members
Authors: Bernut Audrey , Viljoen Albertus , Dupont Christian , Sapriel Guillaume , Blaise Mickaël , Bouchier Christiane , Brosch Roland , de Chastellier Chantal , Herrmann Jean‐Louis , Kremer Laurent
Published: November 2015

In mycobacteria, MmpL proteins represent key components that participate in the biosynthesis of the complex cell envelope. Whole genome analysis of a spontaneous rough morphotype variant of Mycobacterium abscessus subsp. bolletii identified a conserved tyrosine that is crucial for the function of MmpL family proteins. Isogenic smooth (S) and rough (R) variants differed by a single mutation linked to a Y842H substitution in MmpL4a. This mutation caused a deficiency in glycopeptidolipid production/transport in the R variant and a gain in the capacity to produce cords in vitro. In zebrafish, increased virulence of the M. bolletii R variant over the parental S strain was found, involving massive production of serpentine cords, abscess formation and rapid larval death. Importantly, this finding allowed us to demonstrate an essential role of Tyr842 in several different MmpL proteins, including Mycobacterium tuberculosis MmpL3. Structural homology models of MmpL4a and MmpL3 identified two additional critical residues located in the transmembrane regions TM10 and TM4 that are facing each other. We propose that these central residues are part of the proton‐motive force that supplies the energy for substrate transport. Hence, we provide important insights into mechanistic/structural aspects of MmpL proteins as lipid transporters and virulence determinants in mycobacteria.
Shoemaker's Analysis of Realization: A Review
Authors: Pineda David , Vicente Agustín
Published: November 2015

Sydney Shoemaker has been arguing for more than a decade for an account of the mind–body problem in which the notion of realization takes centre stage. His aim is to provide a notion of realization that is consistent with the multiple realizability of mental properties or events, and which explains: (i) how the physical grounds the mental; and (ii) why the causal work of mental events is not screened off by that of physical events. Shoemaker's proposal consists of individuating properties in terms of causal powers, and defining realization as a relation of inclusion between sets of causal powers. Thus, as the causal powers that define a mental property are a subset of the causal powers that characterize a physical property, it can be said that physical properties realize mental properties. In this paper we examine the physicalist credentials of Shoemaker's mind–body theory in relation to three important issues: the direction of the relation of dependence that the theory is committed to; the possibility of mental properties existing without being anchored by physical properties; and the compatibility of the theory with the causal closure of the physical world. We argue that Shoemaker's theory is problematic in all three respects. After that we consider whether the theory should count as a mind–body theory at all, given that it seems to be committed to a distorted view of mental properties.
Bacillus Calmette‐Guérin (BCG) Vaccination in Infancy and Risk of Childhood Diabetes
Authors: Rousseau Marie‐Claude , El‐Zein Mariam , Conus Florence , Legault Laurent , Parent Marie‐Elise
Published: November 2015

Background

A narrow time window in infancy may be relevant for the aetiology of immune‐mediated type 1 diabetes. We investigated whether a non‐specific immune stimulation in the first year of life, as resulting from Bacillus Calmette‐Guérin (BCG) vaccination, was associated with childhood diabetes.

Methods

Using data from a birth cohort assembled through linkage of administrative databases, 78 492 subjects born in 1974 were the object of the present analysis. Information was extracted from the birth, death, and BCG vaccination registries. Diabetes‐related health services were obtained from administrative health databases (physician billing claims and hospitalisation data) until 1994. Subjects were classified as having diabetes according to two validated definitions: (1) ≥2 diabetes‐related medical visits within 2 years or ≥1 hospitalisation for diabetes; and 2) ≥4 diabetes‐related medical visits within 2 years. Cox proportional hazards regression was used to estimate adjusted hazard ratios (HR) and 95% confidence interval (CI), adjusted for potential confounders.

Results

Forty‐four per cent of subjects were BCG vaccinated in the first year of life. According to the first and second definition, respectively, 293 (0.37%) and 230 (0.29%) subjects were classified as having diabetes. There was no association between BCG vaccination in the first year of life and risk of diabetes with either definition (HRdef1 = 0.92, 95% CI 0.73, 1.17; HRdef2 = 1.04, 95% CI 0.80, 1.37), and results did not differ by sex.

Conclusions

Given the potentially critical importance of the exposure window and paucity of studies addressing BCG vaccination timing in relation to diabetes risk, this question deserves further investigation.
Heart rate complexity: A novel approach to assessing cardiac stress reactivity
Authors: Brindle Ryan C. , Ginty Annie T. , Phillips Anna C. , Fisher James P. , McIntyre David , Carroll Douglas
Published: November 2015

Correlation dimension (D2), a measure of heart rate (HR) complexity, has been shown to decrease in response to acute mental stress and relate to adverse cardiovascular health. However, the relationship between stress‐induced changes in D2 and HR has yet to be established. The present studies aimed to assess this relationship systematically while controlling for changes in respiration and autonomic activity. In Study 1 (N = 25) D2 decreased during stress and predicted HR reactivity even after adjusting for changes in respiration rate, and cardiac vagal tone. This result was replicated in Study 2 (N = 162) and extended by including a measure of cardiac sympathetic activity; correlation dimension remained an independent predictor of HR reactivity in a hierarchical linear model containing measures of cardiac parasympathetic and sympathetic activity and their interaction. These results suggest that correlation dimension may provide additional information regarding cardiac stress reactivity above that provided by traditional measures of cardiac autonomic function.
Toward More “Evidence‐Informed” Policy Making?
Authors: Head Brian W.
Published: November 2015

The quality of public decision making depends significantly on the quality of analysis and advice provided through public organizations. Champions of “evidence‐informed” policy making claim that rigorous evaluation practices can significantly improve attainment of cost‐effective outcomes. After decades of experience, performance information is more sophisticated, but evaluation practices and capabilities vary enormously. Public agencies gather and process vast amounts of information, but there has been little analysis of how this information is actually utilized for policy and program improvement. This article examines how government agencies use evidence about policy and program effectiveness, with attention to four themes: (1) the prospects for improving “evidence‐informed” policy making, (2) the diversity of practices concerning evidence utilization and evaluation across types of public agencies and policy arenas, (3) recent attempts to “institutionalize” evaluation as a core feature of policy development and budget approval, and (4) the relationships between public agencies and nongovernmental sources of expertise.
Oral health needs in individuals with trisomy 18 and trisomy 13: Implications for dental professionals
Authors: Bruns Deborah , Martinez Alyssa , All Campbell Emily
Published: November 2015

The purpose of this study was to examine oral health needs and dental care in individuals with trisomy 18 and trisomy 13 (full, mosaic, partial and other, mixed types). Primary feeding method was also examined. Data was collected from a parent‐completed, mixed method survey (TRIS Survey). Mean age in months was 120.2 (range 38 to 394 months) and 133 (range 36 to 405 months), respectively, for trisomy 18 and trisomy 13 individuals. Results indicated the majority of individuals received routine dental care from their family dentist. Approximately 80% in both groups needed some form of specialized dental care. Close to 25% and 30% of trisomy 18 and trisomy 13 individuals, respectively, required hospital admission for specialized dental care. Responses indicated the presence of excessive plaque and tooth decay across the groups with a higher incidence for individuals with trisomy 13. Although not the primary form of intake, over half of the individuals received oral feedings. Implications for dental care and management are provided along with the need for additional research to confirm or disconfirm this study's findings.
Cordon Pricing and Land‐Use Regulation
Authors: Kono Tatsuhito , Kawaguchi Hiroya
Published: November 2015

This study explores the simultaneous imposition of cordon pricing and land‐use regulations in a continuous and closed monocentric city with homogeneous households. Results reveal the optimal level of a single cordon toll and its location and the optimal floor area ratio (FAR) regulation, clarifying what distortions remain in the existence of cordon pricing and FAR regulation. Among other results, this paper shows that, with an optimal cordon toll, FAR regulation should alternate between a minimum and a maximum regulation, both inside and outside the cordon line.
Prevalence and causes of hearing impairment in Africa
Authors: Mulwafu W. , Kuper H. , Ensink R. J. H.
Published: November 2015

Objective

To systematically assess the data on the prevalence and causes of hearing impairment in Africa.

Methods

Systematic review on the prevalence and causes of hearing loss in Africa. We undertook a literature search of seven electronic databases (EMBASE, PubMed, Medline, Global Health, Web of Knowledge, Academic Search Complete and Africa Wide Information) and manually searched bibliographies of included articles. The search was restricted to population‐based studies on hearing impairment in Africa. Data were extracted using a standard protocol.

Results

We identified 232 articles and included 28 articles in the final analysis. The most common cut‐offs used for hearing impairment were 25 and 30 dB HL, but this ranged between 15 and 40 dB HL. For a cut‐off of 25 dB, the median was 7.7% for the children‐ or school‐based studies and 17% for population‐based studies. For a cut‐off of 30 dB HL, the median was 6.6% for the children or school‐based studies and 31% for population‐based studies. In schools for the deaf, the most common cause of hearing impairment was cryptogenic deafness (50%) followed by infectious causes (43%). In mainstream schools and general population, the most common cause of hearing impairment was middle ear disease (36%), followed by undetermined causes (35%) and cerumen impaction (24%).

Conclusion

There are very few population‐based studies available to estimate the prevalence of hearing impairment in Africa. Those studies that are available use different cut‐offs, making comparison difficult. However, the evidence suggests that the prevalence of hearing impairment is high and that much of it is avoidable or treatable.
Treatment of zinc toxicosis in a dog with chelation usingd‐penicillamine
Authors: Lee Ye‐Rin , Kang Min‐Hee , Park Hee‐Myung
Published: November 2015

Objective

To describe chelation therapy withd‐penicillamine for treatment of zinc toxicosis in a dog.

Case Summary

A 1.5‐year‐old intact female Maltese dog weighing 2.7 kg was presented with acute, progressive anorexia, lethargy, pigmenturia, and melena. The owner reported that the dog had ingested a hook from a dog leash made of a zinc‐based alloy 9 days prior. A blood transfusion was administered and an abdominal radiograph revealed a metal‐dense foreign body in the stomach. Laboratory findings revealed a serum zinc concentration of 1845.12 μg/dL (reference interval, 70–200 μg/dL) and a decreased hematocrit that remained low despite removal of the zinc foreign body. On day 3, another blood transfusion was performed andd‐penicillamine therapy was instituted. After the administration ofd‐penicillamine, the clinical signs and hemogram progressively improved and the dog was discharged 2 days later. On day 9 after initial presentation, the hematocrit and platelet values were within normal limits and the serum zinc concentration was 280.16 μg/dL.

New or Unique Information Provided

This case demonstrates the use ofd‐penicillamine in the treatment of zinc toxicosis. Serum zinc concentration appeared to decline more rapidly after administration ofd‐penicillamine than before chelation therapy. This is the first report to evaluate serial serum zinc concentrations before and during chelation therapy withd‐penicillamine.
Is rate–pressure product of any use in the isolated rat heart? Assessing cardiac ‘effort’ and oxygen consumption in the Langendorff‐perfused heart
Authors: Aksentijević Dunja , Lewis Hannah R. , Shattock Michael J.
Published: November 2015

New Findings

What is the central question of this study?

Rate–pressure product (RPP) is commonly used as an index of cardiac ‘effort’. In canine and human hearts (which have a positive force–frequency relationship), RPP is linearly correlated with oxygen consumption and has therefore been widely adopted as a species‐independent index of cardiac work. However, given that isolated rodent hearts demonstrate a negative force–frequency relationship, its use in this model requires validation.

What is the main finding and its importance?

Despite its widespread use, RPP is not correlated with oxygen consumption (or cardiac ‘effort’) in the Langendorff‐perfused isolated rat heart. This lack of correlation was also evident when perfusions included a range of metabolic substrates, insulin or β‐adrenoceptor stimulation.

Langendorff perfusion of hearts isolated from rats and mice has been used extensively for physiological, pharmacological and biochemical studies. The ability to phenotype these hearts reliably is, therefore, essential. One of the commonly used indices of function is rate–pressure product (RPP); a rather ill‐defined index of ‘work’ or, more correctly, ‘effort’. Rate–pressure product, as originally described in dog or human hearts, was shown to be correlated with myocardial oxygen consumption (). Despite its widespread use, the application of this index to rat or mouse hearts (which, unlike the dog or human, have a negative force–frequency relationship) has not been characterized. The aim of this study was to examine the relationship between RPP and in Langendorff‐perfused rat hearts. Paced hearts (300–750 beats min−1) were perfused either with Krebs–Henseleit (KH) buffer (11 mm glucose) or with buffer supplemented with metabolic substrates and insulin. The arteriovenous oxygen consumption () was recorded. Metabolic status was assessed using 31P magnetic resonance spectroscopy and lactate efflux. Experiments were repeated in the presence of isoprenaline and in unpaced hearts where heart rate was increased by cumulative isoprenaline challenge. In KH buffer‐perfused hearts, increased with increasing heart rate, but given that left ventricular developed pressure decreased with increases in rate, RPP was not correlated with , lactate production or phosphocreatine/ATP ratio. Although the provision of substrates or β‐adrenoceptor stimulation changed the shape of the RPP– relationship, neither intervention resulted in a positive correlation between RPP and oxygen consumption. Rate–pressure product is therefore an unreliable index of oxygen consumption or ‘cardiac effort’ in the isolated rat heart.
Myoglobin and the regulation of mitochondrial respiratory chain complex IV
Authors: Yamada Tatsuya , Takakura Hisashi , Jue Thomas , Hashimoto Takeshi , Ishizawa Rie , Furuichi Yasuro , Kato Yukio , Iwanaka Nobumasa , Masuda Kazumi
Published: November 2015

Key points

Mitochondrial respiration is regulated by multiple elaborate mechanisms.

It has been shown that muscle specific O2 binding protein, Myoglobin (Mb), is localized in mitochondria and interacts with respiratory chain complex IV, suggesting that Mb could be a factor that regulates mitochondrial respiration.

Here, we demonstrate that muscle mitochondrial respiration is improved by Mb overexpression via up‐regulation of complex IV activity in cultured myoblasts; in contrast, suppression of Mb expression induces a decrease in complex IV activity and mitochondrial respiration compared with the overexpression model.

The present data are the first to show the biological significance of mitochondrial Mb as a potential modulator of mitochondrial respiratory capacity.

Mitochondria are important organelles for metabolism, and their respiratory capacity is a primary factor in the regulation of energy expenditure. Deficiencies of cytochrome c oxidase complex IV, which reduces O2 in mitochondria, are linked to several diseases, such as mitochondrial myopathy. Moreover, mitochondrial respiration in skeletal muscle tissue tends to be susceptible to complex IV activity. Recently, we showed that the muscle‐specific protein myoglobin (Mb) interacts with complex IV. The precise roles of mitochondrial Mb remain unclear. Here, we demonstrate that Mb facilitates mitochondrial respiratory capacity in skeletal muscles. Although mitochondrial DNA copy numbers were not altered in Mb‐overexpressing myotubes, O2 consumption was greater in these myotubes than that in mock cells (Mock vs. Mb‐Flag::GFP: state 4, 1.00 ± 0.09 vs. 1.77 ± 0.34; state 3, 1.00 ± 0.29; Mock: 1.60 ± 0.53; complex 2‐3‐4: 1.00 ± 0.30 vs. 1.50 ± 0.44; complex IV: 1.00 ± 0.14 vs. 1.87 ± 0.27). This improvement in respiratory capacity could be because of the activation of enzymatic activity of respiratory complexes. Moreover, mitochondrial respiration was up‐regulated in myoblasts transiently overexpressing Mb; complex IV activity was solely activated in Mb‐overexpressing myoblasts, and complex IV activity was decreased in the myoblasts in which Mb expression was suppressed by Mb‐siRNA transfection (Mb vector transfected vs. Mb vector, control siRNA transfected vs. Mb vector, Mb siRNA transfected: 0.15 vs. 0.15 vs. 0.06). Therefore, Mb enhances the enzymatic activity of complex IV to ameliorate mitochondrial respiratory capacity, and could play a pivotal role in skeletal muscle metabolism.
Effects of acute and chronic systemic methamphetamine on respiratory, cardiovascular and metabolic function, and cardiorespiratory reflexes
Authors: Hassan Sarah F. , Wearne Travis A. , Cornish Jennifer L. , Goodchild Ann K.
Published: November 2015

Key points

Methamphetamine (METH) abuse is escalating worldwide, with the most common cause of death resulting from cardiovascular failure and hyperthermia; however, the underlying physiological mechanisms are poorly understood.

Systemic administration of METH in anaesthetised rats reduced the effectiveness of some protective cardiorespiratory reflexes, increased central respiratory activity independently of metabolic function, and increased heart rate, metabolism and respiration in a pattern indicating that non‐shivering thermogenesis contributes to the well‐described hyperthermia.

In animals that showed METH‐induced behavioural sensitisation following chronic METH treatment, no changes were evident in baseline cardiovascular, respiratory and metabolic measures and the METH‐evoked effects in these parameters were similar to those seen in saline‐treated or drug naïve animals.

Physiological effects evoked by METH were retained but were neither facilitated nor depressed following chronic treatment with METH.

These data highlight and identify potential mechanisms for targeted intervention in patients vulnerable to METH overdose.

Methamphetamine (METH) is known to promote cardiovascular failure or life‐threatening hyperthermia; however, there is still limited understanding of the mechanisms responsible for evoking the physiological changes. In this study, we systematically determined the effects on both autonomic and respiratory outflows, as well as reflex function, following acute and repeated administration of METH, which enhances behavioural responses. Arterial pressure, heart rate, phrenic nerve discharge amplitude and frequency, lumbar and splanchnic sympathetic nerve discharge, interscapular brown adipose tissue and core temperatures, and expired CO2 were measured in urethane‐anaesthetised male Sprague‐Dawley rats. Novel findings include potent increases in central inspiratory drive and frequency that are not dependent on METH‐evoked increases in expired CO2 levels. Increases in non‐shivering thermogenesis correlate with well‐described increases in body temperature and heart rate. Unexpectedly, METH evoked minor effects on both sympathetic outflows and mean arterial pressure. METH modified cardiorespiratory reflex function in response to hypoxia, hypercapnia and baroreceptor unloading. Chronically METH‐treated rats failed to exhibit changes in baseline sympathetic, cardiovascular, respiratory and metabolic parameters. The tonic and reflex cardiovascular, respiratory and metabolic responses to METH challenge were similar to those seen in saline‐treated and drug naive animals. Overall, these findings describe independent and compound associations between physiological systems evoked by METH and serve to highlight that a single dose of METH can significantly impact basic homeostatic systems and protective functions. These effects of METH persist even following chronic METH treatment.
Design and Fabrication of a Polymeric Microfilter for Medical Applications
Authors: Surace Rossella , Bellantone Vincenzo , Trotta Gianluca , Basile Vito , Modica Francesco , Fassi Irene
Published: November 2015

This paper reports on design, fabrication, and characterization of a microfilter to be used in biomedical applications. The microfilter, with mesh of 80 μm, is fabricated by micro-injection molding process in polymeric material (polyoxymethylene (POM)) using a steel mold manufactured by micro-electrical discharge machining process. The characteristics of the filter are investigated by numerical simulation in order to define a suitable geometry for micro-injection molding. Then, different process configurations of parameters (melt temperature, injection velocity, mold temperature, holding pressure and time, cooling time, pressure limit) are tested in order to obtain the complete part filling via micro-injection molding process preventing any defects. Finally, the component is dimensionally characterized and the process parameters optimized to obtain the maximum filtration capacity.
A Review on Bistable Composite Laminates for Morphing and Energy Harvesting
Authors: Emam Samir A. , Inman Daniel J.
Published: November 2015

Bistable composite laminates have received a considerable attention due to their fabulous behavior and potential for morphing and energy harvesting. A bistable or multistable laminate is a type of composite structure that exhibits multiple stable static configurations. The characterization of unsymmetric fiber-reinforced laminated composite plates as a bistable structure is well established and quantitatively determined after about 30 years of research. As predicting cured shapes of unsymmetric composite laminates became well identified, attention was directed to the design of these structures for morphing applications. Bistable composite laminates have attracted researchers as a morphing structure because a bistable structure settles at one of its equilibrium positions without demanding continuous power to remain there. If the structure is triggered to leave an equilibrium position, it will snap or jump to the other equilibrium position. The snapthrough response is highly geometrically nonlinear. With the increased demand for broadband vibration energy harvesters, bistable composite laminates, which are able to gain large-amplitude vibrations in snapthrough motion, have recently attracted attention. This paper aims to summarize, review, and assess references and findings concerned with the response of bistable composite laminates for morphing and energy harvesting to date. It also highlights the remaining challenges and possible future research work as research in bistable composites transitions from phenomena to application.
Vibrations of Elliptically Shaped Bearings in Strain Wave Gearings
Authors: Adams Christian , Skowronek Adam , Bös Joachim , Melz Tobias
Published: November 2015

The bearing of a strain wave gearing and the covering thin-walled cup, i.e., the so-called flexspline, are elliptically deformed. This leads to a characteristic excitation of vibration. In this paper, a model for describing the vibration of elliptically deformed bearings is presented. First, the flexspline stiffness is calculated using an a priori finite element (FE) analysis that is validated with measured data. Second, the deformation of the bearing and the flexspline is calculated by superimposing single loads. A numerical study shows that vibrations are mainly caused by the rotation of the ellipse. Furthermore, two types of impulses, i.e., negative impulses and positive impulses, lead to vibration excitation. The negative impulses are caused by the balls passing the angular position of the contact force maxima, while the positive impulses are caused by the balls impacting the surfaces of the races due to the radial tolerance of the bearing. Both negative and positive impulses coincide with characteristic frequencies of the nondeformed bearing. If the surfaces of the bearing are considered to be rough, the characteristic frequencies are not affected. Therefore, characteristic frequencies of nondeformed bearings can be utilized to describe vibrations of elliptically shaped bearings as well.
Experimental and Computational Evaluation of Performance and Water Management Characteristics of a Bio-Inspired Proton Exchange Membrane Fuel Cell
Authors: Saripella Bhaskar P. , Koylu Umit O. , Leu Ming C.
Published: November 2015

A bio-inspired proton exchange membrane (PEM) fuel cell with a flow field that mimics a leaf pattern is experimentally and computationally evaluated. Experiments are conducted using a transparent assembly for direct visualization of liquid water within the microchannels. Polarization and power curves are also obtained while advanced simulations are performed to predict distributions of pressure, velocity, and concentrations. The same measurements and computations are also performed for a single serpentine fuel cell. The results establish the superior water management and performance characteristics of the bio-inspired fuel cell in comparison to a conventional one. They also help elucidate the underlying transport mechanisms, validate the computational models, and guide the optimization of bio-inspired fuel cells.
Self-Excited Blade Vibration Experimentally Investigated in Transonic Compressors: Acoustic Resonance
Authors: Holzinger F. , Wartzek F. , Schiffer H.-P. , Leichtfuss S. , Nestle M.
Published: November 2015

This paper investigates the acoustically induced rotor blade vibration that occurred in a state-of-the-art 1.5-stage transonic research compressor. The compressor was designed with the unconventional goal to encounter self-excited blade vibration within its regular operating domain. Despite the design target to have the rotor blades reach negative aerodamping in the near stall region for high speeds and open inlet guide vane, no vibration occurred in that area prior to the onset of rotating stall. Self-excited vibrations were finally initiated when the compressor was operated at part speed with fully open inlet guide vane along nominal and low operating line. The mechanism of the fluid–structure interaction behind the self-excited vibration is identified by means of unsteady compressor instrumentation data. Experimental findings point toward an acoustic resonance originating from separated flow in the variable inlet guide vanes (VIGV). A detailed investigation based on highly resolved wall-pressure data confirms this conclusion. This paper documents the spread in aerodynamic damping calculated by various partners with their respective aeroelastic tools for a single geometry and speed line. This significant spread proves the need for calibration of aeroelastic tools to reliably predict blade vibration. This paper contains a concise categorization of flow-induced blade vibration and defines criteria to quickly distinguish the different types of blade vibration. It further gives a detailed description of a novel test compressor and thoroughly investigates the encountered rotor blade vibration.
The Impact of Blade Loading and Unsteady Pressure Bifurcations on Low-Pressure Turbine Flutter Boundaries
Authors: Waite Joshua J. , Kielb Robert E.
Published: November 2015

The three major aeroelastic issues in the turbomachinery blades of jet engines and power turbines are forced response, nonsynchronous vibrations, and flutter. Flutter primarily affects high-aspect ratio blades found in the fan, fore high-pressure compressor stages, and aft low-pressure turbine (LPT) stages as low natural frequencies and high axial velocities create smaller reduced frequencies. Often with LPT flutter analyses, physical insights are lost in the exhaustive quest for determining whether the aerodynamic damping is positive or negative. This paper underlines some well-known causes of the LPT flutter in addition to one novel catalyst. In particular, an emphasis is placed on revealing how local aerodynamic damping contributions change as a function of unsteady (e.g., mode shape, reduced frequency) and steady (e.g., blade torque, pressure ratio) parameters. To this end, frequency domain Reynolds-averaged Navier–Stokes (RANS) CFD analyses are used as computational wind tunnels to investigate how aerodynamic loading variations affect flutter boundaries. Preliminary results show clear trends between the aerodynamic work influence coefficients and variations in exit Mach number and back pressure, especially for torsional mode shapes affecting the passage throat. Additionally, visualizations of qualitative bifurcations in the unsteady pressure phases around the airfoil shed light on how local damping contributions evolve with steady loading. Final results indicate a sharp drop in aeroelastic stability near specific regions of the pressure ratio, indicating a strong correlation between blade loading and flutter. Passage throat shock behavior is shown to be a controlling factor near the trailing edge, and as with critical reduced frequency, this phenomenon is shown to be highly dependent on the vibratory mode shape.
Adaptation of Phase-Lagged Boundary Conditions to Large Eddy Simulation in Turbomachinery Configurations
Authors: Mouret Gaelle , Gourdain Nicolas , Castillon Lionel
Published: November 2015

With the increase in computing power, large eddy simulation (LES) emerges as a promising technique to improve both knowledge of complex physics and reliability of turbomachinery flow predictions. However, these simulations are very expensive for industrial applications, especially when a 360  deg configuration should be considered. The objective of this paper is thus to adapt the well-known phase-lagged conditions to the LES approach by replacing the traditional Fourier series decomposition (FSD) with a compression method that does not make any assumptions on the spectrum of the flow. Several methods are reviewed, and the proper orthogonal decomposition (POD) is retained. This new method is first validated on a flow around a circular cylinder with rotating downstream blocks. The results show significant improvements with respect to the FSD. It is then applied to unsteady Reynolds-averaged Navier–Stokes (URANS) simulations of a single-stage compressor in 2.5D and 3D as a first validation step toward single-passage LES of turbomachinery configuration.
Measurement of 3D Flow Structure of Viscoelastic Fluid Using Digital Holographic Microscope
Authors: Li Xiao-Bin , Oishi Masamichi , Matsuo Tsukasa , Oshima Marie , Li Feng-Chen , Li Song-Jing
Published: November 2015

This paper aims to develop a three-dimensional measurement approach to investigate the flow structures of viscoelastic fluid in the curved microchannel by using digital holographic microscope (DHM). With the advantage of DHM, the real-time three-dimensional measurement for the complex flow field can be accomplished. The measurment system uses off-axis holographic / interferometric optical setup for the target, and 3D3C particle tracking velocimetry (PTV) can be achieved based on the analysis of phase information of holograms. To diagnose the chaotic flow inside the microchannel, the 3D temporal positions of tracer particles in the volume of 282μm × 282μm × 60μm have been detected and real-time velocity vectors were calculated based on the PTV algorithm. The measured flow field was then compared with the results obtained by using confocal micro particle image velocimetry (PIV). This technique is proven to be successful for the measurements of microfluidic flow, especially for the truly real-time 3D motions.
Heat Transfer Enhancement of Elastic Turbulence in Curved Microchannel
Authors: Li Dongyang , Li Xiaobin , Li Fengchen
Published: November 2015

Flow instabilities of generalized turbulence can prompt heat transfer enhancement in Newtonian fluids. In curved microchannel, viscoelastic fluid also leads to complex behavior even flow instabilities at very low Reynolds number (Re) conditions, and hereby the potential heat transfer enhancement. The primary purpose of this paper is to obtain the influence factors on heat transfer in virtue of viscoelastic instabilities. Microelectronics manufacturing technology was taken to fabricate the microchips of curvilinear microchannels. Platinum films were used as micro heater and temperature measurement sensor, which were embedded in the polydimethylsiloxane (PDMS) microchannel. In our experiments, the polymer solution flow with large enough elasticity becomes quite irregular; even gets into elastic turbulence compared with sucrose solution flow. With a lower thermal conductivity, the polymer solutions show higher heat transfer intensity than sucrose solutions. Heat transfer enhancement due to elastic turbulence in a curved is hereby identified. Furthermore, viscoelastic effects act to augment the heat transfer effect in terms of the convective heat transfer coefficient.
Approach for Configuring a Standardized Vessel for Processing Radioactive Waste Slurries
Authors: Bamberger Judith Ann , Enderlin Carl W. , Minette Michael J. , Holton Langdon K.
Published: November 2015

A standardized vessel design is being considered at the Waste Treatment and Immobilization Plant (WTP) that is under construction at Hanford, Washington. The standardized vessel design will be used for storing, blending, and chemical processing of slurries that exhibit a variable process feed including Newtonian to non-Newtonian rheologies over a range of solids loadings. Developing a standardized vessel is advantageous and reduces the testing required to evaluate the performance of the design.

The objectives of this paper are to: 1) present a design strategy for developing a standard vessel mixing system design for the pretreatment portion of the waste treatment plant that must process rheologically and physically challenging process streams, 2) identify performance criteria that the design for the standard vessel must satisfy, 3) present parameters that are to be used for assessing the performance criteria, and 4) describe operation of the selected technology.

Vessel design performance will be assessed for both Newtonian and non-Newtonian simulants which represent a range of waste types expected during operation.

Desired conditions for the vessel operations are the ability to shear the slurry so that flammable gas does not accumulate within the vessel, that settled solids will be mobilized, that contents can be blended, and that contents can be transferred from the vessel. A strategy is presented for adjusting the vessel configuration to ensure that all these conditions are met.
General Observations of the Time-Dependent Flow Field Around Flat Plates in Free Fall
Authors: Hærvig Jakob , Lyhne Jensen Anna , Cecilie Pedersen Marie , Sørensen Henrik
Published: November 2015

The free fall trajectories of flat plates are investigated in order to improve understanding of the forces acting on falling blunt objects. The long term goal is to develop a general applicable model to predict free fall trajectories. Numerically the free fall of a flat plate is investigated using a six degrees of freedom (6DOF) solver and a dynamic mesh. To validate the simulation, the trajectories of aluminium plates falling in water are recorded by digital camera recordings and compared to the simulation. The simulation is able to calculate the motion of the plate within each time step with high accuracy, and thereby allowing the whole trajectory to be predicted with fair accuracy.

With the numerical model able to predict the free fall and the complex plate fluid interactions, fluids forces can be extracted for model development in future studies.
Novel Implementation of Fluid-Solid Interaction Analysis in Air Breathing Propulsion Systems
Authors: Song Yangkun , Bayandor Javid
Published: November 2015

A bird strike event is one of the largest threats to the safety of aircraft, yet, the studies conducted to ensure the integrity of aircraft systems have so far been based mainly on empirical data, rather than a numerical analysis. From a wide spectrum of bird strike scenarios, bird ingestion into an aircraft’s propulsion system is the most hazardous. To ensure passenger safety, engine manufacturers are required by the Federal Aviation Administration (FAA) to design engines that can sustain thrust for at least 20 minutes in the event of a catastrophic soft body ingestion incident [1]. To satisfy these regulations, manufactures need to perform a variety of certification tests, but such tests can drastically increase cost, time, and efforts required to develop a final product. To avoid such challenges, a numerical analysis becomes an essential tool.

In order to analyze the dynamic damage response of a propulsion system subjected to bird ingestion, Fluid-Solid Interaction (FSI) must be considered. FSI is a very important phenomenon for most of the engineering applications which requires coupling two complicated disciplines. Previously, a preliminary dynamic damage assessment had been performed on the front fan section of a propulsion system in the event of a soft body impact. In this study, a more precise propulsion system is developed and implemented to predict the dynamic damage evolution of the propulsion system which is subject to a soft body impact.
Dynamic Effects in the Reverse Flow Velocity Field
Authors: Shukla Dhwanil , Hiremath Nandeesh , Raghav Vrishank , Komerath Narayanan
Published: November 2015

At high edgewise flow speeds, reversed flow causes excursions in pitching moment and blade torsion on the rotor blades of helicopters and wind turbines. Our prior work has shown that a yawed fixed wing at angle of attack in reversed flow generates a sharp-edge vortex. The sharp-edge vortex is a primary feature of the flow under the rotor blade. During operation as a rotor blade at high advance ratio in a wind tunnel, stereo PIV results show that the well-formed sharp-edge vortex at 240 degrees azimuth resembles that on a forward-swept wing. This vortex stops growing before 270 degrees and convects with the blade by 300 degrees. Static pressure computed from interpolated velocity data show the effects of vortex-induced radial pressure gradient. This explains the finding of inboard-directed radial flow at 300 degrees azimuth, overcoming centrifugal effects. Viscous stress is shown to have only a minor effect on the static pressure field computation.
Application of an Integrated Flow and DBD Plasma Actuation Model to a High-Lift Airfoil: Part I — RANS
Authors: Shan Hua , Aram Shawn , Lee Yu-Tai
Published: November 2015

An integrated numerical simulation tool that couples the Reynolds averaged Navier-Stokes (RANS) or the large eddy simulation (LES) solver for incompressible flows with the dielectric barrier discharge (DBD) electro-hydrodynamic (EHD) body force model has been developed. The EHD body force model is based on solving the electrostatic equations for the electric potential due to applied voltage and the net charge density due to ionized air. The boundary condition for the charge density on the dielectric surface is obtained from a Space-Time Lumped-Element (STLE) circuit model that accounts for the time and space dependence of air ionization on the input voltage amplitude, frequency, electrode geometry, and dielectric properties. The development of the numerical simulation tool is based on the framework of NavyFOAM using a multi-domain approach. The electric potential equation, the net charge density equation, and the flow equations are solved in separate computational domains. All equations are discretized in space using the cell-centered finite volume method. Parallel computation is implemented using domain-decomposition and message passing interface (MPI). Due to a large disparity in time scales between the electric discharge and the flow, a multiple sub-cycle technique is used in coupling the plasma solver and the flow solver.

This paper focuses on its application to numerical simulation of flow separation and control over a high-lift flapped airfoil at a Reynolds number of 240,000. The 2-D unsteady RANS simulation utilized the Wilcox k-ω, the SST k-ω, and the k-kl-ω turbulence models. For the baseline case, in comparison with the measurement, the k-kl-ω model captures the feature of the unsteadiness of flow field associated with flow separation and shedding of vortices, better than the Wilcox k-ω and SST k-ω models. In the RANS simulations for flow separation control with DBD plasma actuation, the actuator is driven by voltage signals of a continuous or an amplitude-modulated sine waveform with a range of voltage amplitudes. The numerical results indicate that the modulated forcing is more effective than the continuous forcing for a certain range of applied voltages. The electrical power consumption calculated by the plasma model fits to a parabolic curve as a function of the root-mean-square of applied voltage.