bluuebunny/crossref_metadata_2025 huggingface dataset:
Association Between Self‐Reported Sleep Duration and Serum Vitamin D Level in Elderly Korean Adults
Authors: Kim Jeong Hong , Chang Jung Hyun , Kim Dong Young , Kang Ju Wan
Published: December 2014

Objectives

To investigate the association between self‐reported sleep duration and serum vitamin D level in elderly Korean adults.

Design

Cross‐sectional data analysis.

Setting

Korean National Health and Nutrition Examination Survey 2010.

Participants

Noninstitutionalized adults aged 60 to 80 (N = 1,614).

Measurements

The confounding variables were serum 25‐hydroxy vitamin D level, age, sex, body mass index, smoking history, alcohol consumption, and self‐reported daily sun exposure and sleep duration. Self‐reported daily sleep duration was divided into four groups: Q1 (≤4 hours), Q2 (5–6 hours), Q3 (7–8 hours), and Q4 (≥9 hours).

Results

Mean serum vitamin D levels of subjects in the Q1, Q2, Q3, and Q4 groups were 44.18, 48.08, 48.83, and 51.78 nmol/L, respectively. On multivariate linear regression analysis, subjects in the Q2 (B = 3.80, 95% confidence interval (CI) = 0.42–7.19), Q3 (B = 4.89, 95% CI = 1.54–8.24), and Q4 (B = 5.18, 95% CI = 0.78–9.58) groups had significantly higher serum vitamin D levels than subjects in the Q1 group.

Conclusion

Serum vitamin D level is positively associated with self‐reported daily sleep duration in elderly Korean individuals. These results suggest that inadequate sleep duration may be associated with lower vitamin D levels in elderly adults.
Health Outcomes Associated with Polypharmacy in Community‐Dwelling Older Adults: A Systematic Review
Authors: Fried Terri R. , O'Leary John , Towle Virginia , Goldstein Mary K. , Trentalange Mark , Martin Deanna K.
Published: December 2014

Objectives

To summarize evidence regarding the health outcomes associated with polypharmacy, defined as number of prescribed medications, in older community‐dwelling persons.

Design

Systematic review of MEDLINE (OvidSP 1946 to May, Week 3, 2014).

Setting

Community.

Participants

Observational studies examining health outcomes according to number of prescription medications taken.

Measurements

Association between number of medications and health outcomes. Because of the importance of comorbidity as a potential confounder of the relationship between polypharmacy and health outcomes, articles were assessed regarding the quality of their adjustment for confounding.

Results

Of the 50 studies identified, the majority that were rated good in terms of their adjustment for comorbidity demonstrated relationships between polypharmacy and a range of outcomes, including falls, fall outcomes, fall risk factors, adverse drug events, hospitalization, mortality, and measures of function and cognition. However, a number of these studies failed to demonstrate associations, as did a substantial proportion of studies rated fair or poor.

Conclusion

Data are mixed regarding the relationship between polypharmacy, considered in terms of number of medications, and adverse outcomes in community‐dwelling older persons. Because of the challenge of confounding, randomized controlled trials of medication discontinuation may provide more‐definitive evidence regarding this relationship than observational studies can provide.
Nascher's Geriatrics at 100
Authors: Cohen Andrew B.
Published: December 2014

Ignatz Nascher's Geriatrics—the first American medical textbook on aging—turns 100 this year. This essay is a reappraisal, on its centennial, of Nascher's landmark work.
Factors Mediating the Effects of a Depression Intervention on Functional Disability in Older African Americans
Authors: Gitlin Laura N. , Szanton Sarah L. , Huang Jin , Roth David L.
Published: December 2014

Objectives

To determine factors mediating the effects of a depression intervention for older African Americans on functional disability and, secondarily, whether functional improvements mediate intervention effects on depressive symptoms.

Design

Structural equation modeling to examine mediators in a secondary analysis of a randomized trial with 4‐month follow‐up.

Setting

Philadelphia region.

Participants

Community‐dwelling African Americans (≥55) with depressive symptoms living in an urban area (N = 208).

Intervention

Up to 10 one‐hour sessions over 4 months conducted by licensed social workers who provided care management, referrals and linkages, stress reduction techniques, depression knowledge and symptom recognition, and behavioral activation techniques.

Measurements

Main outcome was self‐reported functional difficulty level for 18 basic activities. Mediators included depression severity (Patient Health Questionnaire), depression knowledge and symptom recognition, behavioral activation, and anxiety.

Results

At 4 months, the intervention had positive effects on functional difficulty and all mediators (P < .001). Separate structural equation models indicated that two factors (reduced depressive symptoms (23.5% mediated) and improved depression knowledge and symptom recognition (52.9% mediated)) significantly mediated the intervention's effect on functional disability. Enhancing behavioral activation and decreasing anxiety were not found to mediate improvements in functional disability. The two significant mediators jointly explained 62.5% of the intervention's total effect on functional disability. Functional improvement was not found to mediate the intervention's effect on depressive symptoms.

Conclusion

This multicomponent depression intervention for African Americans has an effect on functional disability that is driven primarily by enhancing symptom recognition and decreasing depressive symptoms. Reduction of functional difficulties did not account for improvements in depressive symptoms. Nonpharmacological treatments for depressive symptoms that enhance symptom recognition in older African Americans can also reduce their functional difficulties with daily living activities.
Associations Between Inflammation and Cognitive Function in African Americans and European Americans
Authors: Windham B. Gwen , Simpson Brittany N. , Lirette Seth , Bridges John , Bielak Lawrence , Peyser Patricia A. , Kullo Iftikhar , Turner Stephen , Griswold Michael E. , Mosley Thomas H.
Published: December 2014

Objectives

To examine associations between specific inflammatory biomarkers and cognitive function in African Americans (AAs) and European Americans (EAs) with prevalent vascular risk factors.

Design

Cross‐sectional analysis using generalized estimating equations to account for familial clustering; standardized β‐coefficients, adjusted for age, sex, and education are reported.

Setting

Community cohort study in Jackson, Mississippi, and Rochester, Minnesota.

Participants

Genetic Epidemiology Network of Arteriopathy (GENOA)–Genetics of Microangiopathic Brain Injury (GMBI) Study participants.

Measurements

Associations between inflammation (high‐sensitivity C‐reactive protein (CRP), interleukin (IL)‐6, soluble tumor necrosis factor (TNF) receptor 1 and 2 (sTNFR1, sTNFR2)) and cognitive function (global, processing speed, language, memory, and executive function) were examined in AAs and EAs (N = 1,965; aged 26–95, 64% women, 52% AA, 75% with hypertension).

Results

In AAs, higher sTNFR2 was associated with poorer cognition in all domains (global: −0.11, P = .009; processing speed: −0.11, P < .001; language: −0.08, P = .002; memory: −0.09, P = .008; executive function: −0.07, P = .03); sTNFR1 was associated with slower processing speed (−0.08, P < .001) and poorer executive function (−0.08, P = .008); higher CRP was associated with slower processing speed (−0.04, P = .024), and higher IL6 was associated with poorer executive function (−0.07, P = .02). In EA, only higher sTNFR1 was associated with slower processing speed (−0.05, P = .007). Associations were not found between cognition and sTNFR2, CRP, or IL6 in EA.

Conclusion

In a population with high vascular risk, adverse associations between inflammation and cognitive function were especially apparent in AAs, primarily involving markers of TNFα activity.
A combined oral contraceptive affects mucosal SHIV susceptibility factors in a pigtail macaque (Macaca nemestrina) model
Authors: Dietz Ostergaard Sharon , Butler Katherine , Ritter Jana M. , Johnson Ryan , Sanders Jeanine , Powell Nathaniel , Lathrop George , Zaki Sherif R. , McNicholl Janet M. , Kersh Ellen N.
Published: December 2014

Background

Injectable hormonal contraception may increase women's risk of HIV acquisition and can affect biological risk factors in animal models of HIV. We established, for the first time, a model to investigate whether combined oral contraceptives (COC) alter SHIV susceptibility in macaques.

Methods

Seven pigtail macaques were administered a monophasic levonorgestrel (LNG)/ethinyl estradiol (EE) COC at 33% or 66% of the human dose for 60 days. Menstrual cycling, vaginal epithelial thickness, and other SHIV susceptibility factors were monitored for a mean of 18 weeks.

Results

Mean vaginal epithelial thicknesses were 290.8 μm at baseline and 186.2 μm during COC (P = 0.0141, Mann–Whitney U‐test). Vaginal pH decreased from 8.5 during treatment to 6.5 post‐treatment (0.0176 two‐tailed t‐test). Measured microflora was unchanged.

Conclusions

COC caused thinning of the vaginal epithelium and vaginal pH changes, which may increase SHIV susceptibility. 0.033 mg LNG + .0066 mg EE appeared effective in suppressing ovulation.
Fifty years in neonatology
Authors: Manley Brett J , Doyle Lex W , Davies Mark W , Davis Peter G
Published: December 2014

Neonatology, the care and study of newborn infants, is a 'young' specialty. Over the last 50 years, there have been many advances in the way that neonatologists care for newborn infants, particularly those born preterm, leading to dramatic improvements in mortality. To illustrate these advances, we describe four eras in neonatology from the point of view of the junior hospital doctor.
Proteomic analysis of mitochondria in respiratory epithelial cells infected with human respiratory syncytial virus and functional implications for virus and cell biology
Authors: Munday Diane C , Howell Gareth , Barr John N , Hiscox Julian A
Published: December 2014

Objectives

The aim of this study was to quantitatively characterise the mitochondrial proteome of airway epithelial cells infected with human respiratory syncytial virus (HRSV), a major cause of paediatric illness.

Methods

Quantitative proteomics, underpinned by stable isotope labelling with amino acids in cell culture, coupled to LC-MS/MS, was applied to mitochondrial fractions prepared from HRSV-infected and mock-infected cells 12 and 24 h post-infection. Datasets were analysed using ingenuity pathway analysis, and the results were validated and characterised using bioimaging, targeted inhibition and gene depletion.

Key findings

The data quantitatively indicated that antiviral signalling proteins converged on mitochondria during HRSV infection. The mitochondrial receptor protein Tom70 was found to act in an antiviral manner, while its chaperone, Hsp90, was confirmed to be a positive viral factor. Proteins associated with different organelles were also co-enriched in the mitochondrial fractions from HRSV-infected cells, suggesting that alterations in organelle dynamics and membrane associations occur during virus infection.

Conclusions

Protein and pathway-specific alterations occur to the mitochondrial proteome in a spatial and temporal manner during HRSV infection, suggesting that this organelle may have altered functions. These could be targeted as part of potential therapeutic strategies to disrupt virus biology.
Effects of supplementation with green tea by‐products on growth performance, meat quality, blood metabolites and immune cell proliferation in goats
Authors: Ahmed S. T. , Lee J.‐W. , Mun H.‐S. , Yang C.‐J.
Published: December 2014

Forty‐eight castrated male goats were used to determine the effects of feeding green tea by‐products (GTB) on growth performance, meat quality, blood metabolites and immune cell proliferation. Experimental treatments consisted of basal diets supplemented with four levels of GTB (0%, 0.5%, 1.0% or 2.0%). Four replicate pens were assigned to each treatment with three goats per replicate. Increasing dietary GTB tended to linearly increase the overall average weight gain and feed intake (p = 0.09). Water holding capacity, pH and sensory attributes of meat were not affected by GTB supplementation, while cooking loss was reduced both linearly and quadratically (p < 0.01). The redness (linear; p = 0.02, quadratic; p < 0.01) and yellowness (quadratic; p < 0.01) values of goat meat were improved by GTB supplementation. Increasing dietary GTB quadratically increased protein and decreased crude fat (p < 0.05), while linearly decreased cholesterol (p = 0.03) content of goat meat. The proportions of monounsaturated fatty acid, polyunsaturated fatty acid (PUFA) and n‐6 PUFA increased linearly (p < 0.01) and n‐3 PUFA increased quadratically (p < 0.05) as GTB increased in diets. Increasing dietary GTB linearly increased the PUFA/SFA (saturated fatty acid) and tended to linearly and quadratically increase (p ≤ 0.10) the n‐6/n‐3 ratio. The thiobarbituric acid‐reactive substances values of meat were lower in the 2.0% GTB‐supplemented group in all storage periods (p < 0.05). Dietary GTB linearly decreased plasma glucose and cholesterol (p < 0.01) and quadratically decreased urea nitrogen concentrations (p = 0.001). The growth of spleen cells incubated in concanavalin A and lipopolysaccharides medium increased significantly (p < 0.05) in response to GTB supplementation. Our results suggest that GTB may positively affect the growth performance, meat quality, blood metabolites and immune cell proliferation when supplemented as a feed additive in goat diet.
Comparative survival pattern of the syntopic pine and stone martens in a trapped rural area in France
Authors: Ruette S. , Vandel J.‐M. , Albaret M. , Devillard S.
Published: December 2014

Very little is known about the population dynamics of pine martens Martes martes and stone martens Martes foina in Europe, and even less about the impact of human activities, such as trapping, hunting and road traffic, on populations, despite their crucial importance for deriving reliable conservation and management strategies. We used multistate capture–recapture models to analyse capture–recapture histories that combined information on radio‐tracking data and on recoveries of dead martens. This formulation, based on conditional probabilities, also allowed us to estimate the contribution of trapping and hunting to overall mortality, accounting for detection failures and trapping exposure. We applied this approach to estimate age‐ and sex‐specific survivals of pine martens (N = 40) and stone martens (N = 38) in the same rural area in France, where both species could be legally trapped and hunted. Annual survivals of adults were similar, and estimated at 0.49 for both species [± 0.12 standard deviation (sd) for pine martens; ± 0.10 sd for stone martens]. The annual probability of dying from trapping and hunting was estimated at 0.21 and 0.19 for adult pine and stone martens, respectively. At the individual level, a negative linear relationship was observed between stone marten's survival and trapping exposure, but this was not the case for pine martens, which experienced far lower exposure to trapping. These results confirm that trapping and hunting could have a large impact on marten populations. Vehicle collisions were the second major cause of mortality for both species in our study area. This paper presents the first estimates of survival for syntopic stone and pine martens in Europe and is an important step towards population dynamics modelling of these species.
Exploring why junk foods are ‘essential’ foods and how culturally tailored recommendations improved feeding in Egyptian children
Authors: Kavle Justine A. , Mehanna Sohair , Saleh Gulsen , Fouad Mervat A. , Ramzy Magda , Hamed Doaa , Hassan Mohamed , Khan Ghada , Galloway Rae
Published: December 2014

In Egypt, the double burden of malnutrition and rising overweight and obesity in adults mirrors the transition to westernized diets and a growing reliance on energy‐dense, low‐nutrient foods. This study utilized the trials of improved practices (TIPs) methodology to gain an understanding of the cultural beliefs and perceptions related to feeding practices of infants and young children 0–23 months of age and used this information to work in tandem with 150 mothers to implement feasible solutions to feeding problems in Lower and Upper Egypt. The study triangulated in‐depth interviews (IDIs) with mothers participating in TIPs, with IDIs with 40 health providers, 40 fathers and 40 grandmothers to gain an understanding of the influence and importance of the role of other caretakers and health providers in supporting these feeding practices. Study findings reveal high consumption of junk foods among toddlers, increasing in age and peaking at 12–23 months of age. Sponge cakes and sugary biscuits are not perceived as harmful and considered ‘ideal’ common complementary foods. Junk foods and beverages often compensate for trivial amounts of food given. Mothers are cautious about introducing nutritious foods to young children because of fears of illness and inability to digest food. Although challenges in feeding nutritious foods exist, mothers were able to substitute junk foods with locally available and affordable foods. Future programming should build upon cultural considerations learned in TIPs to address sustainable, meaningful changes in infant and young child feeding to reduce junk foods and increase dietary quality, quantity and frequency.
The Park Grass Experiment and next‐generation approaches: local adaptation of sweet vernal grass revisited
Authors: von Wettberg Eric J. B. , Vance Wendy , Rowland Diane L.
Published: December 2014

Long‐term ecological experiments provide unique opportunities to observe the effects of natural selection. The Park Grass Experiment at Rothamsted Experiment Station in Hertfordshire, UK, is the longest running ecological experiment that incorporates fertilization treatments and has been ongoing since 1856. In the 1970s, local adaptation was observed in the grass Anthoxanthum odoratum to the elevated soil aluminium levels of the fertilized plots. Gould et al. () have utilized this system to reevaluate the extent of local adaptation, first documented nearly 45 years ago (Snaydon ), and to use emerging molecular approaches to identify candidate genes for the adaptation. From their work, they identify several plausible candidate loci for aluminium tolerance. This work shows the power of long‐term field‐based trials in a scientific age concentrated on rapidly emerging molecular techniques often utilized in short, narrowly focused laboratory or controlled environment experiments. The current study clearly illustrates the benefits gained by combining these molecular approaches within long‐term monitoring experiments that can be regularly revisited in a changing world and used to address questions on evolutionary scales.
The phage tail tape measure protein, an inner membrane protein and a periplasmic chaperone play connected roles in the genome injection process of E. coli phage HK97
Authors: Cumby Nichole , Reimer Kelly , Mengin‐Lecreulx Dominique , Davidson Alan R. , Maxwell Karen L.
Published: December 2014

Phages play critical roles in the spread of virulence factors and control of bacterial populations through their predation of bacteria. An essential step in the phage lifecycle is genome entry, where the infecting phage must productively interact with the components of the bacterial cell envelope in order to transmit its genome out of the viral particle and into the host cell cytoplasm. In this study, we characterize this process for the Escherichia coli phage HK97. We have discovered that HK97 genome injection requires the activities of the inner membrane glucose transporter protein, PtsG, and the periplasmic chaperone, FkpA. The requirements for PtsG and FkpA are determined by the sequence of the phage tape measure protein (TMP). We also identify a region of the TMP that mediates inhibition of phage genome injection by the HK97 superinfection exclusion protein, gp15. This region of the TMP also determines the PtsG requirement, and we show that gp15‐mediated inhibition requires PtsG. Based on these data, we present a model for the in vivo genome injection process of phage HK97 and postulate a mechanism by which the inhibitory action of gp15 is reliant upon PtsG.
A metabolomic study in oats (Avena sativa) highlights a drought tolerance mechanism based upon salicylate signalling pathways and the modulation of carbon, antioxidant and photo‐oxidative metabolism
Authors: SÁNCHEZ‐MARTÍN JAVIER , HEALD JIM , KINGSTON‐SMITH ALISON , WINTERS ANA , RUBIALES DIEGO , SANZ MARILUZ , MUR LUIS A. J. , PRATS ELENA
Published: December 2014

Although a wealth of information is available on the induction of one or several drought‐related responses in different species, little is known of how their timing, modulation and crucially integration influence drought tolerance. Based upon metabolomic changes in oat (Avena sativa L.), we have defined key processes involved in drought tolerance. During a time course of increasing water deficit, metabolites from leaf samples were profiled using direct infusion–electrospray mass spectroscopy (DI‐ESI‐MS) and high‐performance liquid chromatography (HPLC) ESI‐MS/MS and analysed using principal component analysis (PCA) and discriminant function analysis (DFA). The involvement of metabolite pathways was confirmed through targeted assays of key metabolites and physiological experiments. We demonstrate an early accumulation of salicylic acid (SA) influencing stomatal opening, photorespiration and antioxidant defences before any change in the relative water content. These changes are likely to maintain plant water status, with any photoinhibitory effect being counteracted by an efficient antioxidant capacity, thereby representing an integrated mechanism of drought tolerance in oats. We also discuss these changes in relation to those engaged at later points, consequence of the different water status in susceptible and resistant genotypes.
Strain and strain rate imaging using speckle tracking in acute allograft rejection in children with heart transplantation
Authors: Sehgal Swati , Blake Jennifer M. , Sommerfield Julie , Aggarwal Sanjeev
Published: December 2014

Acute allograft rejection is a major cause of morbidity and mortality following heart transplantation. There is no reliable noninvasive test to diagnose rejection. We aimed to investigate the accuracy of strain by speckle tracking echocardiography in the detection of acute rejection. We identified acute rejection episodes in patients followed at a single transplant center. Data were collected at baseline, during rejection and two follow‐up points. Peak systolic radial and circumferential strain at the level of papillary muscles and peak systolic longitudinal strain from apical four‐chamber view were analyzed offline. ANOVA was used for comparison between groups. p value ≤0.05 was considered significant. Fifteen rejection episodes were identified. There were no differences in the fractional shortening, LV posterior wall thickness, E/A, septal E/E’, septal S’, lateral E/E’, lateral S’, or MPI during rejection, compared to baseline. There was a significant increase in the LV mass during a rejection episode (47.5 vs. 34.4 g/ht2.7 [p = 0.03]). The peak systolic radial strain (18.3 vs. 26.5; p = 0.03), longitudinal strain (−11.7 vs. −14.6; p = 0.05), and circumferential strain (−14.4 vs. −21.7; p = 0.05) declined significantly during rejection. In conclusion, peak systolic radial, longitudinal and circumferential strain decline and LV mass increases during an episode of rejection.
Intramolecular Proton Transfer in 2‐(2′‐hydroxyphenyl)oxazolo[4,5‐b]pyridine: Evidence for Tautomer in the Ground State
Authors: Chipem Francis A. S. , Malakar Ashim , Krishnamoorthy Govindarajan
Published: December 2014

The intramolecular proton transfer in a newly synthesized molecule, 2‐(2′‐hydroxyphenyl)oxazolo[4,5‐b]pyridine (HPOP) is studied using UV‐visible absorption, fluorescence emission, fluorescence excitation and time‐resolved fluorescence spectroscopy. In the ground state, the molecule exists as cis‐ and trans‐enol in all the solvents. However, in dioxane, alcohols, acetonitrile, dimethylformamide and dimethylsulfoxide the keto tautomer is also observed in the ground state. Dual fluorescence is observed in HPOP where the large Stoke shifted emission is due to emission from the excited‐state intramolecular proton transfer product, whereas the other emission is the normal emission from enol form. The fluorescence (both normal and tautomer emission) of HPOP is less than those of corresponding benzoxazole and imidazopyridine derivatives. This reveals that the nonradiative decay becomes more efficient upon substitution of electronegative atom on the charge acceptor group. The pH studies substantiate the conclusion that (unlike in its imidazole analog) the third ground state species is the keto tautomer and not the monoanion. The effect of temperature on cis‐enol‐trans‐enol‐keto equilibrium and the nonradiative deactivation from the excited state are also investigated.
Experimental Rotordynamic Coefficient Results for: (a) A Labyrinth Seal With and Without Shunt Injection and (b) A Honeycomb Seal
Authors: Soto A. Elias A. , Childs Dara W.
Published: December 2014

Centrifugal compressors are increasingly required to operate at higher pressures, speeds, and fluid density. In these conditions, compressors are susceptible to rotordynamic instabilities. To remedy this situation, labyrinth seals have sometimes been modified by using shunt injection. In shunt injection, the gas is taken from the diffuser or discharge volute and injected into an upstream chamber of the balance-piston labyrinth seal. The injection direction can be radial or against rotation. This study contains the first measured rotordynamic data for labyrinth seals with shunt injection. A comparison has been made between conventional labyrinth seals, labyrinth seal with shunt injection (radial and against rotation), and a honeycomb seal. Labyrinth seals with injection against rotation are better able to control rotordynamic instabilities than labyrinth seals with radial injection; however, the leakage is slightly higher. The leakage comparison for all seals demonstrates that the honeycomb seal has the best flow control. Test data are presented for a top rotor surface velocity of 110 m/sec, a supply pressure of 13.7 bars, and IPr = 0.95 (injection pressure is 1.05 = 1/0.95 times the seal inlet pressure). For these conditions, and considering effective damping, the labyrinth seal with injection against rotation is better than the honeycomb seal when the pressure ratio across the seal PR<0.45. On the other hand, the honeycomb seal is better when PR>0.45. The effectiveness of the shunt-injection against rotation in developing effective damping is reduced with increasing rotor surface velocity.
Oxide/Oxide Ceramic Matrix Composites in Gas Turbine Combustors
Authors: Razzell Anthony G. , Molliex Ludovic , Holmquist Magnus , Sudre Olivier
Published: December 2014

Gas turbine combustor concepts designed to give improved control of NOx emissions require the usage of hot uncooled walls. The main material properties needed in this application include mechanical and chemical stability at temperatures in excess of 1400°C for long times (>10 000 hours). Composites made from single crystal oxide fibre reinforced oxide with a compatible high temperature stable weak oxide interphase are potential candidate materials to meet these requirements. Alumina was chosen as a model material, unidirectional and 2D composites were processed and a suitable weak zirconia interphase was designed. The process was scaled-up to make production of larger panels and components possible. Mechanical testing was carried out at room temperature to characterise the performance of the material in the as produced and thermally aged condition. Room temperature mechanical properties compared well with other current ceramic composites and excellent high temperature stability was demonstrated. The applicability of the composite as a material for uncooled combustor walls is to be further assessed by evaluation in a combustor test rig. Results from computational fluid dynamics and finite element calculations as well as results from combustor rig tests of monolithic and composite ceramic tiles will be presented.
The Centrifugal Compressor Inducer
Authors: Rodgers C.
Published: December 2014

The function of the centrifugal compressor inducer is to provide wide flow margins from the design flow to the stall and choke flow limits, together with high static pressure recovery. At transonic conditions the inducer becomes the critical to impeller performance in that shock losses and blockage growth diminish stable flow range and may trigger near vertical stage characteristics. The paper covers the various types of inlet configurations upstream of the inducer, followed by a review of the state-of-art inducer design for centrifugal compressors, culminating with some research developments in transonic inducer blading characteristics.
Design Issues for the Methane-Steam Reformer of a Chemically Recuperated Gas Turbine Cycle
Authors: Carcasci Carlo , Harvey Simon
Published: December 2014

Significant research effort is currently centered on developing advanced gas turbine systems for electric power generation applications. A number of innovative gas turbine cycles have been proposed lately, including the Humid Air Turbine (HAT), and the Chemically Recuperated Gas Turbine (CRGT). The potential of the CRGT cycle lies in the ability to generate power with a high efficiency while achieving ultra-low NO emissions without the need for selective catalytic reduction of the exhaust gases. However, much of the work that has been published on such cycles is restricted to a discussion of the thermodynamic potential of the cycle, and little work has focussed on discussion of some of the specific design issues associated with such a cycle.

More specifically, design of the chemical recuperation heat recovery device involves a complex design trade-off in order to achieve a design with acceptable hot and cold-side pressure drops and acceptable overall dimensions.

The design of such a heat recovery device is more complex than that of a traditional heat recovery steam generator (HRSG), since the methane steam reformer must not only allow sufficient heat transfer to occur, but also allow a sufficient cold side residence time, so that the methane steam reforming reactions can come close to equilibrium, ensuring maximal methane conversion. In this work, the authors present a code capable of performing the design of a methane steam reformer heat recovery device based on a heat exchanger geometry similar to that of a traditional HRSG. The purpose of the paper is to discuss the key parameters relevant to the design of a CRGT MSR reactor, and how these parameters interact with the rest of the cycle. Various design options are discussed, and the results of a parametric analysis are presented, leading to the identification of several suitable geometries.
Design and Off-Design Analysis of a CRGT Cycle Based on the LM2500-STIG Gas Turbine
Authors: Carcasci Carlo , Facchini Bruno , Harvey Simon
Published: December 2014

Significant research effort is currently centered on developing advanced gas turbine systems for electric power generation applications. A number of innovative gas turbine cycles have been proposed lately, including the Humid Air Turbine (HAT), and the Chemically Recuperated Gas Turbine (CRGT). The potential of the CRGT cycle lies in the ability to generate power with a high efficiency while achieving ultra-low NO emissions without the need for selective catalytic reduction of the exhaust gases. Much of the research work published on the CRGT cycle is restricted to an analysis of the thermodynamic potential of the cycle. However, a detailed performance analysis of such cycles requires the development of a suitable cycle simulation code, capable of simulating cycle operation at the design point and in part load conditions. In this paper, the authors present a modular code for complex gas turbine cycle simulations. The code includes a module for design and off-design simulation of the methane-steam reformer chemical heat recovery device of a CRGT cycle. The code is then used to perform a detailed design and off-design performance analysis of a CRGT cycle based on the LM2500-STIG cycle adapted for chemical recuperation.
The Influence of Impeller Flow Channel Modification on Aerodynamic Performance of a Centrifugal Compressor Stage
Authors: Paroubek Jan , Kynčl Jiří
Published: December 2014

The modifications of meridional form and blade thickness of the impeller of an industrial radial compressor stage (impeller outlet blade angle 32 deg., relative width parameter 0.05) have been designed to extend the operating range of the stage in the area of higher flow rates and to reduce aerodynamic losses in this region. Quasi-3D calculations of the flow pattern in both original and modified impeller flow channels have been carried out to assess the influence of channel form change. The aerodynamic performance of the stage operating with both impellers has been tested on a test rig. The original stage was equipped with varied diffuser only, the modified one was tested with both vaned and vaneless diffusers. Detailed measurements of the flow field behind the impeller outlet have also been carried out. The results of these investigations are presented. Aerodynamic performance and losses in individual flow parts of the stages are compared and discussed.
Multi-Objective Optimisation of Systems Architectures for Distributed Aero-Engine Control Systems
Authors: Thompson H. A. , Fleming P. J. , Chipperfield A. J.
Published: December 2014

The increasing use of embedded intelligence to produce smart sensors and actuators offers great potential benefits in adopting a distributed control strategy in aerospace applications. There are many advantages to be gained: fewer and shorter buses, intrinsic partitioning, smaller control box size, increased health monitoring, increased system flexibility and reduced vulnerability to hazardous events. However, this has to be traded off against the problems of greater complexity, processor diversity, accessibility, exposure of electronics to severe environments, power distribution, software production costs and management. In this paper how multi-objective optimisation can be applied to this problem for the application of military gas turbine engines is considered.
An AGARD Working Group Study of 3D Navier-Stokes Codes Applied to Single Turbomachinery Blade Rows
Authors: Dunham John , Meauzé Georges
Published: December 2014

Computer codes which solve the Reynolds-averaged Navier-Stokes equations are now used by manufacturers to design turbomachines, but there is no consensus among experts about which grids and which turbulence models are good enough to provide a reliable basis for design decisions. The AGARD Propulsion and Energetics Panel set up a Working Group to help to clarify these issues, by analysing predictions (using as wide a range of codes as possible) of two representative but difficult single blade row test cases: NASA Rotor 37 and an annular turbine cascade tested by DLR. This paper summarises the Group’s results and conclusions.

Recommendations are made about the type and density of grid, which depend on many factors. Although mixing-length turbulence models give good results for quasi-two-dimensional boundary layers, they are essentially unsuitable for turbomachines with their complex end wall flows; it is essential to adopt some kind of turbulent transport model.
A Cyclic Symmetry Analysis for Turbomachine Blade Flutter
Authors: Chiang Hsiao-Wei D. , Chung Meng-Hsuan
Published: December 2014

A frequent cause of turbomachinery blade failure is excessive vibration due to flutter or forced response. One method for dealing with this problem is to increase blade structural damping using either tip or mid-span shroud designs. Unfortunately, most existing aeroelastic analyses deal with a blade alone model which can not be used for system mode analysis. Therefore, judgments based on past experience are used to determine the acceptability of a shrouded blade design.

A new cyclic symmetry analysis has been developed to predict shrouded blade flutter. The method provides a system approach, over and above the standard blade alone approach, for predicting potential aeroelastic problems. Using the blade natural frequencies and mode shapes from a cyclic symmetry finite element model, the unsteady aerodynamic forces of the system mode are calculated. A cyclic symmetry flutter analysis is then performed.

This analysis has been applied to a typical shrouded fan blade to investigate blade flutter. The predicted system mode flutter demonstrated that the blade alone analysis can be non-conservative.
Internal Heat Transfer Enhancement by Two Perforated Baffles in a Rectangular Channel
Authors: Dutta Prashanta , Dutta Sandip , Khan Jamil A.
Published: December 2014

The effect of two in-line inclined baffles on the local heat transfer distributions and the associated frictional losses for a turbulent flow with uniform heating from the top surface of a rectangular channel is presented for different Reynolds numbers. A combination of two baffles of same overall size is used in this experiment. The upstream baffle remains attached to the top heated surface and the position, orientation, and geometry of the other is varied. These inclined perforated baffles combine the three major heat transfer augmentation techniques, i.e., jet impingement, internal flow swirls, and boundary layer separation. The results indicate that placement of two inclined baffles augment the overall heat transfer coefficient significantly along with the local heat transfer distribution. The pattern of local Nusselt number ratio strongly depends on the position, orientation, and geometry of the second plate. Like single inclined baffles and rib mounted channels, two baffles offer more pressure drop at higher flow Reynolds number.
A Novel and Compact Marine Gas Turbine Propulsion System
Authors: Kazatzis Panteleimon , Singh Riti , Pilidis Pericles , Locquet Jean-Jacques
Published: December 2014

The power-speed requirements of warships and the poor part load efficiency of simple cycle gas turbines has given rise to the design of many ship installations where two types of gas turbines are used. A large type for high speed, at full power, and a small one for cruise. It is common to mount two units of each type. This design results in a large amount of bulky and heavy ducting, much more voluminous and heavy than the gas turbines themselves.

The present paper outlines an investigation into a novel intercooled split-cycle with some deck mounted components. This reduces the requirement for internal ducts in the ships hull, essentially, to those needed by the cruise engine.

The engine performance has been predicted and a comparison is carried out between a traditional installation and the one investigated. An estimate has been carried out of the flow conditions of the duct to assess the change in losses for operation in the cruise and the full power condition. The new scheme appears to be promising.
Performance Enhancement of a Gas Turbine With Humid Air and Utilization of LNG Cold Energy
Authors: Song C. H. , Ro S. T.
Published: December 2014

It is well known that a cycle performance can be improved considerably by adopting humid air to a simple gas turbine. Further improvement can be achieved by utilizing LNG (liquified natural gas) cold energy which is obtained during vaporization process of natural gas from liquid to gas state. Qualitatively well known fact of high specific power and improvement of efficiency are analyzed quantitatively for various cases. These include comparisons of power, efficiency and other important operating parameters for the cases of a simple cycle and HAT cycle with and without utilization of LNG cold energy. Compared with simple cycle, HAT cycle got 48% increase in total work, 16% increase in efficiency and HAT-LNG cycle got each 54%, 17% increases at 10 pressure ratio.

An analysis shows that a reasonable matching exists between the amount of LNG as fuel and the energy required to control inlet air temperature. It should be also admitted that use of a high cost liquified natural gas is inevitable for transportation of fuel from production site to consumer.
A New Propulsion System Proposal for Civil Supersonic Transport: The Retractable Fan Concept
Authors: Huete Jon I. , Singh R.
Published: December 2014

The next civil supersonic aircraft project will pose a number of challenges. The propulsion system for this aircraft will have to achieve economic operation for both supersonic and subsonic regime while meeting the intended noise and pollutant emissions regulation. Whilst there are a number of proposed engines for the next generation civil supersonic aircraft, they all exhibit difficulties inherent in the engine duty. The present paper offers a simple solution based on retractable fans. The key for the success of the concept is the single stage double pass tip turbine that drives the fan. Characteristics of this unique turbine such as extra-high power output at reasonable efficiencies and low metal temperatures along with some performance aspects of the power plant are discussed. Although further investigation is still required, the performance of the system merits consideration. The work was undertaken by one of the authors as part of his MSc research project.
Technologies for Reducing Greenhouse Gas Emissions From Fossil Fuels
Authors: Audus Harry , Freund Paul
Published: December 2014

In recent years, the possibility of climate change has begun to be considered seriously. Options available today can help reduce emissions at relatively little overall cost but may be able to achieve only moderate reductions. If it becomes necessary to reduce emissions further, it is likely there will be opportunities for new technologies as well as making greater use of existing ones. Bearing in mind the time required to develop and deploy new energy supply technologies on a large-scale, it is only sensible to adopt a precautionary stance. This requires better understanding of the potential of technologies not yet in widespread use and stimulation of the development and deployment of promising ones. The EEA Greenhouse Gas R&D Programme is working to improve understanding of technologies for reducing greenhouse gas emissions from fossil fuels. This is an example of effective co-operative action between different countries and industries. Membership is worldwide; through this work, members are able to learn about new technologies and share experiences. This paper reviews the work of the IEA Greenhouse Gas R&D Programme.

The established options for reducing emissions include improving energy efficiency, substitution of lower-carbon fuels for high-carbon fuels, and introduction of alternative energy sources. If deep reductions in emissions are required, discussion tends to focus on alternatives to fossil fuels even though the latter provide a very large proportion of the energy used today. To avoid disruptive changes, the world will need to be able to continue using fossil fuels but in a climate-friendly way.

Capture and storage of carbon dioxide could deliver deep reductions in emissions from fossil fuels but the technology is still in its infancy — this is the subject of on-going work by the IEA Greenhouse Gas R&D Programme. Enhancement of natural sinks, such as forests, could also help by sequestering atmospheric carbon dioxide. Use of biomass for power generation has also been examined to see how it compares as a large-scale mitigation option compared with capture and storage. Methane is another important greenhouse gas, produced by many human activities. Technology can help reduce emissions of methane; examples of some of these technologies will be described. The mechanism of Activities Implemented Jointly is potentially important for application of all of these options and the Greenhouse Gas Programme is working to improving understanding about viable options and methods of delivering successful projects.
Detailed Measurements Within a Selection of Pipe Diffusers for Centrifugal Compressors
Authors: Bennett I. , Tourlidakis A. , Elder R. L.
Published: December 2014

It is well established that the flow between the impeller tip and the diffuser throat is very influential on the performance and flow range of a centrifugal compressor stage. Detailed measurements of a parametric selection of pipe diffusers have been carried out within this region using a combination of conventional pneumatic and high speed pressure transducers.

Four pipe diffuser designs were examined. The first and datum consisted of 31 pipes, representing a design with minimal meridional step (or sidewall expansion) between impeller tip and diffuser throat. The step size was increased to 1.3 for the second design resulting in a 22 pipe diffuser. A further increase of sidewall expansion ratio to 1.7 with 13 pipes was completed following favourable results from the 22 pipe tests. The final diffuser was of hybrid design consisting of an oval rather than circular throat cross-section. This departure allowed for a 13 pipe diffuser without sidewall expansion.

Flow range and performance comparisons are made in addition to detailed measurements which clearly show that strong planar pulsations dominate the distorted diffuser throat flow. Larger pressure pulsations are quantified for the designs with low numbers of pipes.
System Identification of Jet Engines
Authors: Sugiyama Nanahisa
Published: December 2014

System identification plays an important role in advanced control systems for jet engines, in which controls are performed adaptively using data from the actual engine and the identified engine. An identification technique for jet engine using the Constant Gain Extended Kalman Filter (CGEKF) is described. The filter is constructed for a two-spool turbofan engine. The CGEKF filter developed here can recognize parameter change in engine components and estimate unmeasurable variables over whole flight conditions. These capabilities are useful for an advanced Full Authority Digital Electric Control (FADEC). Effects of measurement noise and bias, effects of operating point and unpredicted performance change are discussed. Some experimental results using the actual engine are shown to evaluate the effectiveness of CGEKF filter.