bluuebunny/crossref_metadata_2025 huggingface dataset:
Architectural proteins CTCF and cohesin have distinct roles in modulating the higher order structure and expression of the CFTR locus
Authors: Gosalia Nehal , Neems Daniel , Kerschner Jenny L. , Kosak Steven T. , Harris Ann
Published: August 2014

Higher order chromatin structures across the genome are maintained in part by the architectural proteins CCCTC binding factor (CTCF) and the cohesin complex, which co-localize at many sites across the genome. Here, we examine the role of these proteins in mediating chromatin structure at the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CFTR encompasses nearly 200 kb flanked by CTCF-binding enhancer-blocking insulator elements and is regulated by cell-type-specific intronic enhancers, which loop to the promoter in the active locus. SiRNA-mediated depletion of CTCF or the cohesin component, RAD21, showed that these two factors have distinct roles in regulating the higher order organization of CFTR. CTCF mediates the interactions between CTCF/cohesin binding sites, some of which have enhancer-blocking insulator activity. Cohesin shares this tethering role, but in addition stabilizes interactions between the promoter and cis-acting intronic elements including enhancers, which are also dependent on the forkhead box A1/A2 (FOXA1/A2) transcription factors (TFs). Disruption of the three-dimensional structure of the CFTR gene by depletion of CTCF or RAD21 increases gene expression, which is accompanied by alterations in histone modifications and TF occupancy across the locus, and causes internalization of the gene from the nuclear periphery.
Rosette modes of oscillations of rotating stars caused by close degeneracies. III. JWKB analysis
Authors: Takata Masao
Published: August 2014

An asymptotic analysis is developed to describe rosette modes of oscillations in rotating stars, which have been recently discovered in numerical computations. The name of the modes comes from characteristic rosette patterns of the distributions of the kinetic-energy density on the meridional plane. As have been shown in the previous papers in this series, the physical reason for the formation of these modes is the rotation-induced interaction among several gravity modes with almost the same frequencies and successive spherical degrees of the same parity. This formation process is described in the framework of the quasi-degenerate perturbation theory. In this paper, the matrix eigenvalue problem, which appears in the perturbation analysis, is solved analytically, using asymptotic expressions of eigenfunctions, which are obtained by assuming that the wavelength of oscillations in the horizontal direction is sufficiently small. By further assuming that the number of interacting modes is large, simple expressions of the eigenfunctions and eigenfrequencies of rosette modes are obtained. Because these expressions can describe the essential part of characteristics of rosette modes, they are useful in understanding general properties of rosette modes that are common to any equilibrium structure.
Dieback of Pinus nigra Seedlings Caused by a Strain of Trichoderma viride
Authors: Li Destri Nicosia M. G. , Mosca S. , Mercurio R. , Schena L.
Published: August 2014

Four different fungi (Trichoderma viride, T. harzianum, Phomopsis sp., and Mortierella sp.) were isolated from 6-year-old Pinus nigra plants showing stunting and high incidence of mortality in a reforestation area of the National Park of Abruzzo, Lazio, and Molise (central Italy). Tests conducted on P. nigra revealed the pathogenic behavior of T. viride isolates with 30 to 80% mortality in artificially inoculated 2-year-old seedlings. The pathogenicity of these isolates was also observed in 10-year-old P. nigra trees and on lemon fruit. This result, in agreement with the constant isolation of T. viride from diseased plants, suggests the possible role of this fungus in the decline of P. nigra plants. T. harzianum and two reference isolates of T. viridarium and T. trixiae did not cause any symptoms, while Phomopsis sp. and Mortierella sp. caused limited necroses around the inoculation point in a few seedlings. Their role in the decline of P. nigra seedlings was considered irrelevant. According to phylogenetic analyses, pathogenic isolates of T. viride clustered in a very uniform group containing strains from different geographic origin and hosts, but none previously reported as a biocontrol agent.
Evaluation of chromogenic medium and direct latex agglutination test for detection of group B streptococcus in vaginal specimens from pregnant women in Lebanon and Kuwait
Authors: Ghaddar Nahed , Alfouzan Wadha , Anastasiadis Elie , Al Jiser Tamima , Itani Saad Eddine , Dernaika Racha , Eid Toufic , Ghaddar Ali , Charafeddine Adib , Dhar Rita , El Hajj Hiba
Published: August 2014

This study was undertaken to evaluate chromogenic medium and a direct latex agglutination test (DLA) for detection of Group B Streptococcus (GBS) in the vaginal specimens of pregnant women, and to ascertain the prevalence of GBS in this population in Kuwait and Lebanon. Vaginal swabs, collected from women at 35–37 weeks of gestation, were cultured on 5 % sheep blood agar (SBA), colistin nalidixic acid agar (CNA), Strept B Select chromogenic agar (SBS) as well as Lim enrichment broth in 168 cases in Lebanon while only SBA was used for 1391 samples in Kuwait. In addition, vaginal samples from 102 GBS-positive and 20 GBS-negative women near the time of delivery were collected in Kuwait for evaluation of the DLA test. During the study period, the prevalence of GBS colonization was determined to be 20.7 % (288/1391) in Kuwait while 18.4 % (31) of 168 pregnant women in Lebanon had vaginal cultures positive for GBS. By direct plating of vaginal swabs on the three media used, the isolation rates of GBS were 51.6, 64.5 and 77.4 % on SBA, CNA and SBS, respectively, which increased to 90.35, 93.1 and 96.8 %, respectively, following subculture in Lim broth after 18 h of incubation. The sensitivity of the DLA test was found to be dependent on the density of GBS colonization, resulting in 100 % sensitivity and 100 % specificity for heavy (>102 c.f.u. per swab) and moderately heavy (50–100 c.f.u. per swab) growth of GBS. However, for vaginal specimens yielding <50 c.f.u. per swab, the sensitivity, specificity, positive and negative predictive values of the DLA test were 100, 55.5, 63.6 and 100 %, respectively. In conclusion, a chromogenic agar, such as SBS, and a DLA test can be used for rapid detection of GBS in pregnant women. The DLA test, in particular, could prove to be a useful tool for immediate detection of GBS in women near delivery so that intrapartum antibiotic prophylaxis can be initiated.
The exon junction complex is required for definition and excision of neighboring introns in Drosophila
Authors: Hayashi Rippei , Handler Dominik , Ish-Horowicz David , Brennecke Julius
Published: August 2014

Splicing of pre-mRNAs results in the deposition of the exon junction complex (EJC) upstream of exon–exon boundaries. The EJC plays crucial post-splicing roles in export, translation, localization, and nonsense-mediated decay of mRNAs. It also aids faithful splicing of pre-mRNAs containing large introns, albeit via an unknown mechanism. Here, we show that the core EJC plus the accessory factors RnpS1 and Acinus aid in definition and efficient splicing of neighboring introns. This requires prior deposition of the EJC in close proximity to either an upstream or downstream splicing event. If present in isolation, EJC-dependent introns are splicing-defective also in wild-type cells. Interestingly, the most affected intron belongs to the piwi locus, which explains the reported transposon desilencing in EJC-depleted Drosophila ovaries. Based on a transcriptome-wide analysis, we propose that the dependency of splicing on the EJC is exploited as a means to control the temporal order of splicing events.
Selective enrichment of damaged DNA molecules for ancient genome sequencing
Authors: Gansauge Marie-Theres , Meyer Matthias
Published: August 2014

Contamination by present-day human and microbial DNA is one of the major hindrances for large-scale genomic studies using ancient biological material. We describe a new molecular method, U selection, which exploits one of the most distinctive features of ancient DNA—the presence of deoxyuracils—for selective enrichment of endogenous DNA against a complex background of contamination during DNA library preparation. By applying the method to Neanderthal DNA extracts that are heavily contaminated with present-day human DNA, we show that the fraction of useful sequence information increases ∼10-fold and that the resulting sequences are more efficiently depleted of human contamination than when using purely computational approaches. Furthermore, we show that U selection can lead to a four- to fivefold increase in the proportion of endogenous DNA sequences relative to those of microbial contaminants in some samples. U selection may thus help to lower the costs for ancient genome sequencing of nonhuman samples also.
Subcellular localisation of retromer in post‐endocytic pathways of polarised Madin–Darby canine kidney cells
Authors: Mellado Maravillas , Cuartero Yasmina , Brugada Ramon , Verges Marcel
Published: August 2014

Background information

Retromer is required for endosome‐to‐Golgi retrieval of the cation‐independent mannose 6‐phosphate receptor (CI‐MPR), allowing delivery of hydrolases into lysosomes. It is constituted by a conserved heterotrimer formed by vacuolar protein sorting (Vps) gene products Vps26, Vps35 and Vps29, which is in charge of cargo selection, and a dimer of phosphoinositide‐binding sorting nexins (SNXs), which has a structural role. Retromer has been implicated in sorting of additional cargo. Thus, retromer also promotes polymeric immunoglobulin A (pIgA) transcytosis by the pIgA receptor (pIgR) in polarised cells, and considerable evidence implicates retromer in controlling epithelial cell polarity. However, the precise localisation of retromer along the endocytic pathway of polarised cells has not been studied in detail.

Results

Our biochemical analysis using rat liver endosome fractions suggests a distinct distribution pattern. Although subunits of the cargo‐selective complex were enriched in early endosomes (EEs), levels of SNX2 were greater in sorting endosomes. We then immunolocalised the retromer subunits in polarised Madin–Darby canine kidney (MDCK) cells by confocal microscopy. An estimated 25% of total Vps26 and SNX2 localised to EEs, with negligible portions in recycling endosomes as well as in late endosomes and lysosomes. Although Vps26 was in structures of more heterogeneous size and shape than SNX2, these markedly overlapped. In consequence, the two retromer subcomplexes mostly colocalised. When we analysed retromer overlap with its cargo, we found that structures retromer and pIgA+ are independent of those structures retromer and CI‐MPR+. Remarkably, retromer localised preferentially at the transcytotic pathway. Pharmacological inhibition of phosphoinositide 3‐kinase affected the co‐distribution of retromer with pIgA and the CI‐MPR, delaying pIgA progress to the apical surface.

Conclusions

In polarised MDCK cells, we found retromer associated with certain specialised EE‐derived pathways. Our data imply that retromer is largely engaged in pIgA transcytosis in pIgR‐expressing MDCK cells, as opposed to endosome‐to‐Golgi retrieval.
Opinion: conservation of monarch butterflies (Danaus plexippus) could be enhanced with analyses and publication of citizen science tagging data
Authors: Davis Andrew K.
Published: August 2014

Recent declines in the size of overwintering colonies of monarch butterflies (Danaus plexippus) in eastern North America have stimulated calls for greater conservation efforts of the migratory phenomenon. Conservation decisions, however, should be guided by sound science, and the migratory phase of this population is the least‐studied part of its life cycle.

Data from large‐scale citizen science programs can help address this knowledge gap. For over 20 years, volunteers have been tagging migrating monarchs with numbered stickers from MonarchWatch (www.monarchwatch.org), who oversees the management of tagging and recovery records. These data have the potential to vastly improve scientific understanding of the migratory phase (such as identifying spatial and temporal trends in mortality) and help target conservation efforts, but this potential has not yet been fully realised, based on a review of published studies in the last 20 years.

Since citizen science programs are often understaffed and operate on minimal budgets, data analysis may not be a high priority for project staff. To stimulate scientific investigations using tagging data, there are alternative solutions that could be implemented including making data publicly available or soliciting assistance from external scientists. Such efforts would not only benefit research into monarch biology, but would lend scientific credibility to tagging activities.

Tagging monarchs is a popular activity with clear educational value. In my opinion these data could be, however, better utilised to improve the conservation of the migratory phenomenon itself.
SiC Foams Decorated with SnO2 Nanostructures for Room Temperature Gas Sensing
Authors: Karakuscu Aylin , Ponzoni Andrea , Comini Elisabetta , Sberveglieri Giorgio , Vakifahmetoglu Cekdar
Published: August 2014

Cell walls of the commercial silicon carbide (SiC)‐based foams were decorated by one‐dimensional tin dioxide (SnO2) nanostructures. Thermal evaporation of SnO2 powder with the assistance of a Au catalyst in inert atmosphere caused the formation of SnO2 nanobelts on the pore surfaces. The room temperature (RT) ammonia (NH3) and nitrogen dioxide (NO2) gas sensing behaviors were investigated systematically in both dry and humid air atmosphere with/without UV activation. The results were compared to those for bare SnO2 and SiC. It was shown that SiC/SnO2 composite was efficient to detect low concentration of NH3 (10–50 ppm) and NO2 (1–5 ppm) under humid air and UV activation at RT.
Réduction de l'écart d'instruction entre hommes et femmes et taux d'activité des femmes
Authors: GANGULI Ina , HAUSMANN Ricardo , VIARENGO Martina
Published: August 2014

Dans de nombreux pays, on observe une disparition, voire une inversion de l'écart d'instruction entre hommes et femmes. Mais cela se traduit‐il sur le marché du travail? Se fondant sur des données de recensement recueillies dans quarante pays, les auteurs examinent les écarts en termes de taux d'activité entre hommes et femmes, entre femmes mariées et femmes célibataires, ainsi qu'entre mères et femmes sans enfant. Ils constatent que l'ampleur de ces écarts, le rythme auquel ils évoluent et leur lien avec l'écart d'instruction sont très variables d'un pays à l'autre et qu'ils ne s'expliquent toujours pas par d'autres inégalités.
Sous‐déclaration et sous‐estimation du travail des femmes en Malaisie
Authors: FRANCK Anja Karlsson , OLSSON Jerry
Published: August 2014

En général, la collecte des données sur l'activité des femmes mène souvent à une sous‐déclaration et à une sous‐estimation de leur travail. Partant d'un travail de terrain dans l'Etat de Penang, en Malaisie, les auteurs contribuent à la théorisation de la sous‐déclaration des activités rémunérées des femmes dans les enquêtes officielles: si le travail des femmes est souvent dévalorisé, sa sous‐déclaration peut aussi découler de choix stratégiques et pragmatiques. En se déclarant comme femmes au foyer, elles évitent de contester les normes relatives aux rôles des sexes tout en préservant leurs intérêts par la poursuite d'un travail à l'extérieur du ménage.
Les travailleurs domestiques en Europe: que disent les chiffres?
Authors: ABRANTES Manuel
Published: August 2014

Combien y a‐t‐il de travailleurs domestiques dans l'Union européenne? Comment leur nombre évolue‐t‐il? Quelles sont les différences entre pays? Les chiffres montrent une augmentation, en particulier pour s'occuper des enfants et des adultes fragilisés. Alors qu'il existe deux régimes en Europe, celui du Nord, où l'on s'en remet aux services publics, et celui du Sud, qui repose plus sur des solutions d'ordre privé, l'auteur en appelle à une approche plus nuancée et explore le potentiel explicatif des analyses en termes de politiques publiques, de dynamique du marché du travail ou de relations entre hommes et femmes.
Famille et enfants: obstacles ou incitations à l'emploi indépendant des femmes en Norvège?
Authors: RØNSEN Marit
Published: August 2014

La sous‐représentation des femmes parmi les entrepreneurs et les travailleurs indépendants est commune à bien des cultures et des pays, mais ses raisons restent mal comprises. L'auteur examine, pour la Norvège, l'influence de la situation familiale des femmes à cet égard: présence d'enfants et leur âge, rôle du conjoint, ressources financières du ménage. Les résultats montrent que la présence d'enfants n'entrave pas l'emploi indépendant des femmes, qui est corrélé négativement avec la durée du travail du conjoint et positivement avec le fait que celui‐ci est lui‐même travailleur indépendant. Toutefois la direction de ces causalités est difficile à établir.
Medicines management: an interview study of nurses at a secure psychiatric hospital
Authors: Haw Camilla , Stubbs Jean , Dickens Geoff
Published: August 2014

Aims

To explore mental health nurses' knowledge, attitudes and clinical judgement concerning medicines management in an inpatient setting with a view to enhancing training.

Background

Medicines management is a key role of mental health nurses, but little research has been conducted into their training needs.

Design

An exploratory mixed‐methods design was used involving individual interviews with participants to investigate their responses to hypothetical medicine administration scenarios.

Methods

Interviews were held with a convenience sample of 50 Registered Nurses working in a specialist mental health hospital between November 2012–February 2013. Participants were presented with clinical vignettes describing eight scenarios they might encounter as part of their medicines management role and asked about how they would respond. Responses were assessed by two independent raters against ten quality standards underpinning the vignettes.

Results

The median number of responses that were judged to demonstrate adequate awareness of associated quality standards was 4 (range 1–7), indicating that many participants did not appear to be aware of, or compliant with, current UK medicines management guidance and local policy. Many would not report a ‘near miss’ or medicines administration error. There was a lack of awareness of guidance on verbal prescribing, consent to treatment rules and the administration of off‐label/unlicensed drugs. Past year attendance on a medicines management course, time since registration and self‐reported knowledge of national standards for medicines administration did not discriminate between total score on the 10 quality standards.

Conclusion

The medicines management training needs of participants appeared not to be fully met by the existing learning sources. The use of vignettes to assess nurses' training needs requires evaluation in other settings.
Topical KGF treatment as a therapeutic strategy for vaginal atrophy in a model of ovariectomized mice
Authors: Ceccarelli Simona , D'Amici Sirio , Vescarelli Enrica , Coluccio Paolo , Matricardi Pietro , di Gioia Cira , Benedetti Panici Pierluigi , Romano Ferdinando , Frati Luigi , Angeloni Antonio , Marchese Cinzia
Published: August 2014

One of the most frequent complaints for post‐menopausal women is vaginal atrophy, because of reduction in circulating oestrogens. Treatments based on local oestrogen administration have been questioned as topic oestrogens can reach the bloodstream, thus leading to consider their safety as controversial, especially for patients with a history of breast or endometrial cancers. Recently, growth factors have been shown to interact with the oestrogen pathway, but the mechanisms still need to be fully clarified. In this study, we investigated the effect of keratinocyte growth factor (KGF), a known mitogen for epithelial cells, on human vaginal mucosa cells, and its potential crosstalk with oestrogen pathways. We also tested the in vivo efficacy of KGF local administration on vaginal atrophy in a murine model. We demonstrated that KGF is able to induce proliferation of vaginal mucosa, and we gained insight on its mechanism of action by highlighting its contribution to switch ERα signalling towards non‐genomic pathway. Moreover, we demonstrated that KGF restores vaginal trophism in vivo similarly to intravaginal oestrogenic preparations, without systemic effects. Therefore, we suggest a possible alternative therapy for vaginal atrophy devoid of the risks related to oestrogen‐based treatments, and a patent (no. RM2012A000404) has been applied for this study.
The interplay between daily affect and sleep: a 2‐week study of young women
Authors: Kalmbach David A. , Pillai Vivek , Roth Thomas , Drake Christopher L.
Published: August 2014

Little attention has been paid to the relation between daily affect and sleep, as most prior studies have focused instead on the role of pathological mood in the context of sleep disturbance. However, understanding the transaction between normal variations in emotional experiences and sleep can shed light on the premorbid vulnerabilities that trigger the evolution of affect and sleep into more problematic states. The present study used a 2‐week daily sampling approach to examine the impact of day‐to‐day variations in positive and negative affect on nightly self‐reported sleep‐onset latency, sleep duration and sleep quality in a sample of young women. Hierarchical linear modelling revealed temporal relations between positive and negative affect states and sleep parameters. Specifically, different aspects of both positive and negative affect were uniquely predictive of sleep indices, with sadness and serenity acting as the most consistent predictors. Additionally, better sleep quality was predictive of greater happiness the following day. These results highlight the importance of how our daily emotional experiences influence our nightly sleep and, in turn, how our sleep has an impact on our daily affect. Moreover, our findings may offer insight into the progression of normative levels of affect and sleep as they develop into comorbid depression, anxiety and insomnia.
Effects of sleep/wake history and circadian phase on proposed pilot fatigue safety performance indicators
Authors: Gander Philippa H. , Mulrine Hannah M. , van den Berg Margo J. , Smith A. Alexander T. , Signal T. Leigh , Wu Lora J. , Belenky Gregory
Published: August 2014

The Karolinska Sleepiness Scale and Samn–Perelli fatigue ratings, and psychomotor vigilance task performance are proposed as measures for monitoring commercial pilot fatigue. In laboratory studies, they are sensitive to sleep/wake history and circadian phase. The present analyses examined whether they reliably reflect sleep/wake history and circadian phase during transmeridian flight operations. Data were combined from four studies (237 pilots, 730 out‐and‐back flights between 13 city pairs, 1–3‐day layovers). Sleep was monitored (wrist actigraphy, logbooks) before, during and after trips. On duty days, sleepiness, fatigue and mean response speed were measured pre‐flight and at the top of the descent. Mixed‐model analysis of variance examined associations between these measures and sleep/wake history, after controlling for operational factors. Circadian phase was approximated by local (domicile) time in the city where each trip began and ended. More sleep in the 24 h prior to duty was associated with lower pre‐flight sleepiness and fatigue and faster response speed. Sleepiness and fatigue were greater before flights departing during the domicile night and early morning. At the top of the descent, pilots felt less sleepy and fatigued after more in‐flight sleep and less time awake. Flights arriving in the early–mid‐morning (domicile time) had greater sleepiness and fatigue and slower response speeds than flights arriving later. Subjective ratings showed expected associations with sleep/wake history and circadian phase. The response speed showed expected circadian variation but was not associated with sleep/wake history at the top of the descent. This may reflect moderate levels of fatigue at this time and/or atypically fast responses among pilots.
Foreign Entry, Acquisition Target and Host Country Welfare
Authors: Kabiraj Tarun , Sinha Uday Bhanu
Published: August 2014

We discuss entry strategy of a foreign multinational into a local market with initially two asymmetric local firms. We show that greenfield investment occurs when both local cost asymmetry and subsidiary set up cost are small, exporting occurs when both trade cost and technology gap are low, otherwise acquisition occurs. Under acquisition equilibrium the less efficient firm is acquired unless the cost of technology transfer is large enough. We focus on the process of selection of the target firm by constructing sequential offer game, bidding game and repeated offer game. However, the MNC's entry always reduces host country welfare.
Reasons for corporate research and development spin‐outs – the chemical and pharmaceutical industry as example
Authors: Festel Gunter
Published: August 2014

The spin‐out of research and development (R&D) activities from established companies has increased during recent years. The reasons for realising corporate spin‐outs, especially regarding the involvement of financial investors, were investigated based on 30 European case studies within the chemical and pharmaceutical industry. The reasons can be categorised into two groups: an investment and a divestment rationale. Whereas the chemical industry uses both rationales, there are only divestment cases in the pharmaceutical industry. The investment cases within the chemical industry show that R&D spin‐outs can make an important contribution towards the flexibilisation and performance improvement of a company's internal R&D. The divestment cases show that R&D spin‐outs can be a suitable possibility to continue promising R&D activities. The survival rate of the analysed spin‐outs is high and numerous new jobs have been created in the past years, especially in pharmaceutical spin‐outs.
Assessment of the Effect of Population and Diary Sampling Methods on Estimation of School‐Age Children Exposure to Fine Particles
Authors: Che W. W. , Frey H. Christopher , Lau Alexis K. H.
Published: August 2014

Population and diary sampling methods are employed in exposure models to sample simulated individuals and their daily activity on each simulation day. Different sampling methods may lead to variations in estimated human exposure. In this study, two population sampling methods (stratified‐random and random‐random) and three diary sampling methods (random resampling, diversity and autocorrelation, and Markov‐chain cluster [MCC]) are evaluated. Their impacts on estimated children's exposure to ambient fine particulate matter (PM2.5) are quantified via case studies for children in Wake County, NC for July 2002. The estimated mean daily average exposure is 12.9 μg/m3 for simulated children using the stratified population sampling method, and 12.2 μg/m3 using the random sampling method. These minor differences are caused by the random sampling among ages within census tracts. Among the three diary sampling methods, there are differences in the estimated number of individuals with multiple days of exposures exceeding a benchmark of concern of 25 μg/m3 due to differences in how multiday longitudinal diaries are estimated. The MCC method is relatively more conservative. In case studies evaluated here, the MCC method led to 10% higher estimation of the number of individuals with repeated exposures exceeding the benchmark. The comparisons help to identify and contrast the capabilities of each method and to offer insight regarding implications of method choice. Exposure simulation results are robust to the two population sampling methods evaluated, and are sensitive to the choice of method for simulating longitudinal diaries, particularly when analyzing results for specific microenvironments or for exposures exceeding a benchmark of concern.
Biomass-Based, Small-Scale, Distributed Generation of Electricity and Heat Using Integrated Gas Turbine-Fuel Cell Systems
Authors: Buhre B. J. P. , Andries J.
Published: August 2014

The use of a biomass gasifier that drives a gas turbine integrated with a fuel cell, is a potentially very attractive way to generate electricity and heat with a high efficiency and very low emissions. The application of catalytic combustion systems can decrease the emissions even further.

A number of technical and non-technical developments during the last 5 years have significantly enhanced the opportunities for small-scale, distributed power generation, especially for systems based on biomass fuels. These developments are: the liberalisation of the energy market, the growing needs for electricity and heat in developing countries, the increasing demand for ‘green’ or ‘sustainable’ electricity, the near-commercial availability of maintenance-low microturbine generator packages and developments in the field of high temperature fuel cells.

Preliminary system studies have shown that the integration of the different subsystems needs careful evaluation in order to realise the expected high efficiencies. To enable the assessment of the technical feasibility of potentially attractive system designs, adequate, experimentally validated knowledge with regard to biomass gasification, pressurised combustion of the fuel gas and the gas cleaning steps is required.

Possible system designs based on a combination of electrochemical and thermochemical fuel conversion steps are examined and analysed with regard to efficiency, emission and costs.

A system design for application on commercial scale based on present day technology will be considered. At Delft University of Technology, a biomass gasifier has been set up and a conceptual design for a pilot system, to be tested in the slipstream of the Delft 1.5 MWth process development unit, will be presented. The process development unit is described in more detail in [Hoppesteyn, et. al., 1998] and [de Jong et. al., 1998]. In this study, it has been attempted to integrate an SOFC with an existing micro gas turbine that has not especially been adjusted for the integration with the SOFC.
ZP/LTR Control for Turbofan Engines
Authors: Feng Zhengping , Sun Jianguo , Li Qiuhong
Published: August 2014

Among the control methods which have loop transfer recovery ability, such as the LQG/LTR approach, the design of target feedback loop (TFL) is one important step of the procedure for control system design because the performance of the control system designed is limited by its TFL. However in the LQG/LTR approach, the performance in crossing frequency region of TFL designed by Kalman filter or LQ regulator is undesirable, and this results in poor dynamic performance of the control system. In this paper zero placement (ZP) technique is utilized to design TFL for minimum phase plant. The TFL designed by ZP has two advantages over TFL designed by Kalman filter: (1) It has desirable performance in crossing frequency region; (2) Its transfer function approaches to a diagonal matrix at most under the meaning of least square. Obviously if the TFL is recovered well, then the control system has two corresponding features: good dynamic performance and good decoupling performance. Also the ZP/LTR control for a turbofan engine is studied, and simulation results show that the ZP/LTR control system has superior performance to the LQG/LTR control system.
The Use of Hot-Wire Anemometry to Investigate Unsteady Wake-Induced Boundary-Layer Development on a High Lift LP Turbine Cascade
Authors: Wolff Stefan , Brunner Stefan , Fottner Leonhard
Published: August 2014

Recent research has revealed positive effects of unsteady flow on the development of boundary layers in turbine cascades, especially at conditions with a laminar suction side separation bubble at low Reynolds-numbers. Compared to steady flow a reduction of total pressure loss coefficient over a broad range of Reynolds-numbers has been shown. Taking into account the positive effects of wake-induced transition already during the design process, new high lift bladings with nearly the same low losses at unsteady inlet flow conditions could be achieved. This leads to a reduction of weight and cost of the whole turbine module for a constant stage loading.

Unsteady flow in turbomachines is caused by the relative motion of rotor and stator rows. For simulating a moving blade row upstream of a linear cascade in the High Speed Cascade Wind Tunnel of the Universität der Bundeswehr München, a wake generator has been designed and built. The wakes are generated with bars, moving with a velocity of up to 40 m/s in the test section upstream of the cascade inlet plane.

Unsteady flow causes the transition on the surface of the suction side of a low pressure turbine blade to move upstream whenever an incoming wake is present on the surface, moreover a laminar separation bubble can be diminished or even suppressed. In order to detect the effects of wakes on the boundary layer development a new hot-wire data acquisition system is required.

Due to the fact that hot-wires give a good insight into boundary layer development a new hot-wire data acquisition system has been set up. The anemometry system is able of acquiring four channels simultaneously, therefore being capable of logging a triple hot-wire sensor and a bar trigger simultaneously. One further channel is utilised for a once-per revolution trigger. The once-per revolution trigger is used to start the measurement of one data block. Using the well established ensemble averaging technique, 300 ensembles each consisting of 5 wake passing periods have been acquired. Ensemble averaging can be directly performed without any data reduction.

The adaptation of this new hot-wire anemometry data acquisition system to the High Speed Cascade Wind Tunnel of the Universität der Bundeswehr München is pointed out. First results on unsteady periodic boundary layer development of a highly loaded low pressure turbine cascade under unsteady inlet flow conditions are presented. During the present investigation four boundary layer traverses, ranging from x/lax = 0.82 to x/lax = 0.99 (suction side), at steady and unsteady inlet flow conditions (Ubar = 10 m/s) at an outlet Reynolds-number of Re2th = 100000 have been conducted.
Synchronized LDV Measurement in Centrifugal Impeller: Seeding Insemination Set Up and CFD Comparison
Authors: De Lucia M. , Mengoni C. P. , Boncinelli P. , Corradini U.
Published: August 2014

Investigation of flow is necessary for turbomachinery performance analysis.

The development of high performance centrifugal impellers leads to use of higher and higher rotational speeds and smaller and smaller impellers.

The use of intrusive probe for flow evaluation is often inadequate since the probe size can be comparable with the flow passage area and can cause flow distortion so large as to invalidate measurements.

Therefore the use of non-intrusive measurement techniques, which will not alter the flow, is required.

Laser Doppler Velocimetry (LDV) provides an accurate velocity valuation through non-intrusive measurements even in the small hub to shroud area passage.

The right set up of the LDV system is fundamental for accurate measurement; investigated area and working conditions are often completely unknown, so erroneous data, due to system set up, are not easily recognizable. The definition of lens, seeding, insemination technique and LDV parameters can be a source of errors not detectable in measurement phases. Special equipment (seeding inseminating test system and a dedicated wind tunnel) is developed to overcome these problems and to define the right parameters and working conditions to be used in turbomachinery applications. Details of LDV set up are reported in this paper.

In real turbomachinery applications standard LDV measurement (time averaged velocity) could be effected by a non-homogeneous distribution of seeding: e.g. in an impeller in the presence of jet and wake, so it is necessary to link seeding particle passages to their position through the time history in a non-ambiguous way. A customized synchronization technique is presented. Validation of measurements has been achieved by comparing LDV data with results of 3D fully viscous computations.
Development of Continuous Fiber Reinforced Reaction Sintered Silicon Carbide Matrix Composite for Gas Turbine Hot Parts Application
Authors: Kameda Tsuneji , Itoh Yoshiyasu , Hijikata Tsuneo , Okamura Takanari
Published: August 2014

A dense silicon carbide matrix composite reinforced by Hi-Nicalon fibers coated with boron nitride was fabricated by slurry impregnation and subsequent reaction sintering with molten silicon. The effect of the fiber coating structure and the infiltrating metal composition on the mechanical properties of the composite was investigated. The fabrication process for the combustor liner and the shroud segment for a 15 MW gas turbine was developed. The small combustor liner and the shroud segment with some machined notches were evaluated in a combustion test at 1773 K and atmospheric pressure. Excellent durability for gas turbine hot parts was recognized.
SiC Fiber Reinforced Ceramic Matrix Composites for Turbine Engine Applications
Authors: Hatton Kenneth , Landini Dennis , Hemstad Stan , Robinson R. Craig
Published: August 2014

Honeywell Advanced Composites Inc. (ACI) has been working with OEM’s to develop, fabricate, and test ceramic matrix composite (CMC) materials for partial and full replacement of hot section turbine engine components. Using Chemical Vapor Infiltration (CVI) technology, silicon carbide fiber reinforced silicon carbide matrix parts, such as full annular combustion liners and inserts for leading edges on nozzle guide vanes have been fabricated and tested.
Recommended Direction of the Solar/DOE Ceramic Stationary Gas Turbine Program
Authors: Gates S. , Price J. , Parthasarathy V. , Miriyala N. , Jimenez O.
Published: August 2014

Since the advent of the gas turbine more than 60 years ago, performance improvements have followed advances in the mechanical properties of hot section materials. Higher firing temperatures allow increases in cycle efficiency and specific power, becoming key differentiators in the performance of these products. The development of single crystal superalloys and the use of increasingly sophisticated active cooling techniques have been the enabling technologies in this continuing quest. As these metal-based technologies approach their practical limits, the possibilities offered by ceramic materials are attracting more and more attention.
Chemical Vapour Deposition of TBC: An Alternative Process for Gas Turbine Components
Authors: Wahl G. , Nemetz W. , Giannozzi M. , Rushworth S. , Baxter D. , Archer N. , Cernuschi F. , Boyle N.
Published: August 2014

This paper deals with a development of a new process for the deposition of Thermal Barrier Coatings (TBC) based on Chemical Vapour Deposition (CVD). The research program started in September 1998 under a BRITE/Euram III project.

The CVD process involves the evaporation of zirconium and yttrium starting from metal-organic precursors and their reaction with oxygen in a hot wall reactor in order to deposit TBC layers.

The influence of different deposition parameters such as evaporation temperature, pressure and substrate temperature on structure, deposition rate and process yield are described. The characterisation of different precursors behaviour is also described. Preliminary results, obtained with optimised conditions, have shown ZrO2-Y2O3 columnar layers with deposition rates of interest from an industrial point of view.
The Effect of Fuel/Air Mixing on Actuation Authority in an Active Combustion Instability Control System
Authors: Cohen Jeffrey M. , Stufflebeam John H. , Proscia William
Published: August 2014

The authority of an active combustion instability control system was improved by increasing the degree of mixing between a modulated gaseous fuel source and the remainder of the premixed reactants in a low-emissions combustor. Non-reacting acetone PLIF measurements were used to assess the mixedness of various fuel injection configurations, in both time-averaged and phase-locked modes. These configurations were also evaluated in combustion tests in which the authority of the actuator and the ability of the control system to attenuate the instability were measured. The results indicated that both control authority and emissions performance are tied directly to the ability to achieve temporal control over the spatially-averaged fuel/air ratio leaving the premixer at any point in time while simultaneously maintaining the high spatial uniformity of this mixture. The cold-flow diagnostic techniques were proven to be an effective and low-cost method for screening fuel injection concepts.
Reduced NOx Diffusion Flame Combustors for Industrial Gas Turbines
Authors: Feitelberg Alan S. , Tangirala Venkat E. , Elliott Richard A. , Pavri Roointon E. , Schiefer Richard B.
Published: August 2014

This paper describes reduced NOx, diffusion flame combustors that have been developed for both simple cycle and regenerative cycle MS3002 and MS5002 gas turbines. Laboratory tests have shown that when firing with natural gas, without water or steam injection, NOx emissions from the new combustors are about 40% lower than NOx emissions from the standard combustors. CO emissions are virtually unchanged at base load, but increase at part load conditions. Commercial demonstration tests have confirmed the laboratory results.

The standard combustors on both the MS3002 and MS5002 gas turbine are cylindrical cans, approximately 10.5 inches (27 cm) in diameter. A single fuel nozzle is centered at the inlet to each can and produces a swirl stabilized diffusion flame. The walls of the cans are louvered for cooling, and contain an array of mixing and dilution holes that provide the air needed to complete combustion and dilute the burned gas to the desired turbine inlet temperature. The MS3002 turbine is equipped with six combustor cans, while the MS5002 turbine is equipped with twelve combustors.

The new, reduced NOx emissions combustors (referred to as a “lean head end”, or LHE, combustors) retain all of the key features of the conventional combustors; the only major difference is the arrangement of the mixing and dilution holes in the cylindrical combustor cans. By optimizing the number, diameter, and location of these holes, NOx emissions can be reduced considerably. Minor changes are also sometimes made to the combustor cap. The materials of construction, pressure drop, and fuel nozzle are all unchanged.

The differences in NOx emissions between the standard and LHE combustors, as well as the variations in NOx emissions with firing temperature, are well correlated using turbulent flame length arguments. Details of this correlation are presented.
Prediction and Measurement of Thermoacoustic Improvements in Gas Turbines With Annular Combustion Systems
Authors: Krüger Uwe , Hüren Jens , Hoffmann Stefan , Krebs Werner , Flohr Patrick , Bohn Dieter
Published: August 2014

Environmental compatibility requires low emission burners for gas turbine power plants. In the past, significant progress has been made developing low NOx and CO burners by introducing lean premixed techniques in combination with annular combustion chambers. Unfortunately, these burners often have a more pronounced tendency to produce combustion-driven oscillations than conventional burner designs. The oscillations may be excited to such an extent that the risk of engine failure occurs.

For this reason, the prediction of these thermoacoustic instabilities in the design phase of an engine becomes more and more important. A method based on linear acoustic four-pole elements has been developed to predict instabilities of the ring combustor of the 3A-series gas turbines (Krüger et al. (1999b)). The complex network includes the whole combustion system starting from both compressor outlet and fuel supply system and ending at the turbine inlet. The flame frequency response was determined by a transient numerical simulation (step-function approach).

Based on this method, possible improvements for the gas turbine are evaluated in this paper.

First, the burner impedance is predicted theoretically and compared with results from measurements on a test rig for validation of the prediction approach. Next, the burner impedance in a gas turbine combustion system is analyzed and improved thermoacoustically. Stability analyses for the gas turbine combustion system show the positive impact of this improvement.

Second, the interaction of the acoustic parts of the gas turbine system has been detuned systematically in circumferential direction of the annular combustion chamber in order to find a more stable configuration. Stability analyses show the positive effect of this measure as well. The results predicted are compared with measurements from engine operation.

The comparisons of prediction and measurements show the applicability of the prediction method in order to evaluate the thermoacoustic stability of the combustor as well as to define possible countermeasures.
Flamelet Model of NOx in a Diffusion Flame Combustor
Authors: Volkov Dmitry V. , Belokon Alexandr A. , Lyubimov Dmitry A. , Zakharov Vladimir M. , Opdyke George
Published: August 2014

This paper describes a model used for the prediction of the formation of nitrogen oxides in modifications of an industrial diffusion flame, natural gas fueled can combustor. The flow field inside the modified combustors is calculated using a Navier-Stokes solver. A fast chemistry assumption is used for modeling the heat release. Calculated turbulence parameters are then used for the calculation of the NOx formation rate in the post-processing mode with the aid of a flamelet model. The flamelet model permits the use of detailed kinetics with only minimal computational expense. The dependence of the NOx formation rate on the mixture fraction and scalar dissipation is calculated separately for each given condition.

The validation of the model predictions is based on field test data taken earlier on several low NOx modifications recently applied to an industrial, reverse flow can type combustor. The reduced level of NOx emissions was achieved in these modifications by changes in the air distribution within the combustor liner. A comparison of the predicted and measured NOx emission levels shows good potential of the flamelet model.
Active Control Analysis for Combustion-Driven Dynamic Instabilities in Gas-Turbine Combustors
Authors: Mawid M. A. , Park T. W. , Sekar B.
Published: August 2014

A one-dimensional combustor model has been used to simulate combustion-driven dynamic instabilities and then-active control in a generic gas turbine combustor. The combustor model accounts for the unsteady heat release and viscous effects along with choked and open boundaries. Combustion is modeled by using global kinetics for JP-8 fuel. The active control methodology simulated in this study was based upon modulating the primary fuel injection rate. A sinusoidal functional form was implemented to pulse the fuel flow at various frequencies and amounts of pulsated fuel. The numerical results showed that the combustor unstable modes were captured and pressure limit cycle oscillations were attained for certain time lags between the instant of fuel-air mixture injection and heat release. The results also exhibited the effect of varying the time lag to damp out the instability. The simulations also showed that fuel pulsation with frequencies greater or less than the combustor resonant frequencies can suppress the unstable modes.