bluuebunny/crossref_metadata_2025 huggingface dataset:
Testosterone deficiency and quality of life in Australasian testicular cancer survivors: a prospective cohort study
Authors: O'Carrigan B. , Fournier M. , Olver I. N. , Stockler M. R. , Whitford H. , Toner G. C. , Thomson D. B. , Davis I. D. , Hanning F. , Singhal N. , Underhill C. , Clingan P. , McDonald A. , Boland A. , Grimison P. ,   Australian and New Zealand Urogenital and Prostate Cancer Trials Group
Published: August 2014

This is the first prospective study in a contemporary Australian/New Zealand population to determine the prevalence of testosterone deficiency in testicular cancer survivors at 12 months from treatment, and any association with poorer quality of life. Hormone assays from 54 evaluable patients in a prospective cohort study revealed biochemical hypogonadism in 18 patients (33%) and low‐normal testosterone in 13 patients (24%). We found no association between testosterone levels and quality of life (all P > 0.05). Hypogonadal patients should be considered for testosterone replacement to prevent long‐term morbidity.
Les risques de la flexibilité: le travail à temps partiel des femmes dans cinq pays d'Europe
Authors: BLÁZQUEZ CUESTA Maite , MORAL CARCEDO Julián
Published: August 2014

Les marchés du travail européens sont segmentés, avec des emplois flexibles mais précaires, sources d'inégalités entre les travailleurs. La flexibilité du travail à temps partiel facilite la conciliation entre travail et vie de famille et accroît le taux d'activité des femmes, mais induit de nouvelles formes d'inégalités: les auteurs montrent que les travailleurs à temps partiel sont exposés à un plus grand risque de chômage. Ils en appellent donc à prendre des mesures pour instaurer plus d'égalité entre les travailleurs à plein temps et ceux à temps partiel en ce qui concerne la stabilité de l'emploi.
Ségrégation professionnelle selon le sexe en Espagne: exclusion ou confinement?
Authors: DUEÑAS FERNÁNDEZ Diego , IGLESIAS FERNÁNDEZ Carlos , LLORENTE HERAS Raquel
Published: August 2014

En Espagne, le degré de ségrégation professionnelle selon le sexe est parmi les plus élevés d'Europe. Les auteurs étudient les déterminants de la probabilité de travailler dans des professions à dominante masculine ou féminine. Combinant la technique de décomposition d'Oaxaca‐Blinder et une analyse contrefactuelle fondée sur un échantillon de «femmes hypothétiques», ils mettent en évidence les composantes inexpliquées des différentiels de probabilité observés. La dynamique sexuée du marché du travail explique l'essentiel de la ségrégation, plus en raison de la «discrimination positive» en faveur des femmes dans les professions féminisées que de la discrimination négative dans les professions à dominante masculine.
A longitudinal study of aspects of a hospital's family‐centred nursing: changing practice through data translation
Authors: White Chris , Wilson Valerie
Published: August 2014

Aims

To examine how results and data from multiple Family Centred Nursing Index surveys help the development of family‐centred nursing at organizational and ward levels.

Design

A critical analysis of survey data.

Background

The Family Centred Nursing Index provides a valid and reliable assessment of aspects of nursing, through a comprehensive survey of traditional indicators of practice development and a broader range of aspects of practice.

Methods

A survey with 113 questions, each to be answered on 7‐point Likert scale conducted six times in the last 7 years. Surveys have been in 2006, 2008, 2009, 2010, 2011/2012 and 2012/2013. All nurses employed by the organization can participate.

Results

These are reported as means across 19 constructs linked to five key domains and their significance is examined by year and (in the clinical settings) and compared against the organizational (whole population) averages. Ongoing survey and analysis of nurses' views of their work is providing a valuable source of developmental data. The results show unexpected associations between constructs e.g. – a high level of work stress does not correlate with a lower level of job satisfaction (and vice versa). A clear historical picture of many elements of developing family‐centred care is emerging at both the organizational and individual‐ward levels.

Conclusion

This study provides insights into aspects of organizational and wards working environment for nurses and how these aspects of nurses' work interact in unexpected ways. It is appropriate for providing information to organizations and ward teams in relation to their development towards family‐centred cultures.
A meta‐ethnography of patients' experiences of chronic pelvic pain: struggling to construct chronic pelvic pain as ‘real’
Authors: Toye Francine , Seers Kate , Barker Karen
Published: August 2014

Aim

To review systematically and integrate the findings of qualitative research to increase our understanding of patients' experiences of chronic pelvic pain.

Background

Chronic pelvic pain is a prevalent pain condition with a high disease burden for men and women. Its multifactorial nature makes it challenging for clinicians and patients.

Design

Synthesis of qualitative research using meta‐ethnography.

Data Sources

Five electronic bibliographic databases from inception until March 2014 supplemented by citation tracking. Of 488 papers retrieved, 32 met the review aim.

Review Methods

Central to meta‐ethnography is identifying ‘concepts’ and developing a conceptual model through constant comparison. Concepts are the primary data of meta‐ethnography. Two team members read each paper to identify and collaboratively describe the concepts. We next compared concepts across studies and organized them into categories with shared meaning. Finally, we developed a conceptual model, or line of argument, to explain the conceptual categories.

Results

Our findings incorporate the following categories into a conceptual model: relentless and overwhelming pain; threat to self; unpredictability, struggle to construct pain as normal or pathological; a culture of secrecy; validation by diagnosis; ambiguous experience of health care; elevation of experiential knowledge and embodiment of knowledge through a community.

Conclusion

The innovation of our model is to demonstrate, for the first time, the central struggle to construct ‘pathological’ vs. ‘normal’ chronic pelvic pain, a struggle that is exacerbated by a culture of secrecy. More research is needed to explore men's experience and to compare this with women's experience.
The effect of bullying on burnout in nurses: the moderating role of psychological detachment
Authors: Allen Belinda C. , Holland Peter , Reynolds Roslyn
Published: August 2014

Aims

The aim of the study was to examine the relationship between bullying and burnout and the potential buffering effect psychological detachment might have on this relationship.

Background

There is evidence to suggest that bullying is relatively widespread in the nursing profession, with previous studies indicating that bullying is associated with higher levels of burnout. There is, however, limited research focusing on potential moderators of the relationship between bullying and burnout.

Design

A cross‐sectional quantitative study conducted with self‐completed, anonymous questionnaires.

Methods

The study was conducted in 2011 with 762 Registered Nurses in Australia. Two hypotheses were tested with validated measures of bullying, psychological detachment and burnout. The hypotheses were tested using hierarchical regression.

Results

Bullying is positively associated with burnout. Psychological detachment does not significantly moderate the relationship between bullying and burnout.

Conclusion

The results indicate that bullying exacts a strong negative toll on nurses. Ensuring there are workplace policies and practices in place in healthcare organizations to reduce the instances of bullying and proactively address it when it does occur would therefore seem crucial. Individuals may also lower their risk of burning out by psychologically detaching from work.
Rapid diagnosis of the invasive wax scale, Ceroplastes rusci Linnaeus (Hemiptera: Coccoidea: Coccidae) using nested PCR
Authors: Deng J. , Wang X.‐B. , Yu F. , Zhou Q.‐S. , Bernardo U. , Zhang Y.‐Z. , Wu S.‐A.
Published: August 2014

The fig wax scale, Ceroplastes rusci (Linnaeus) (Hemiptera: Coccoidea: Coccidae), is an invasive fruit pest of Afrotropical origin and potentially could become a serious threat to commercial fruit crops in China. C. rusci is difficult to identify owing to the shortage of easily distinguishable morphological characters. A rapid, accurate and reliable method to identify C. rusci in quarantine work is needed to detect further spread. In the present study, we describe a nested PCR method for the molecular identification of C.rusci. The nested PCR primers were designed based on variations in the barcode region of COI sequences between C. rusci and five other Ceroplastes species. A 200‐bp fragment was successfully amplified from 96 C. rusci individuals of seven geographical populations in China and Vietnam, and 13 individuals of two populations in Italy (the type country for C. rusci). These provided diagnostic bands that were not observed in any of five other Ceroplastes species widely distributed in China, namely, C. ceriferus (Fabricius), C. floridensis Comstock, C. japonicus Green, C. pseudoceriferus Green and C. rubens Maskell. Sensitivity tests revealed that diagnostic bands were generated even with a DNA template concentration of ~1.5 × 10−5 ng/μl, and with average DNA template concentrations for adult females, single first‐instar nymphs and eggs of 14.7, 6.3 and 3.0 ng/μl, respectively. Our study demonstrates that the molecular diagnosis of C. rusci using nested PCR is rapid and accurate and shows potential in plant quarantine programmes.
How long should umbilical venous catheters remain in place in neonates who require long‐term (≥5–7 days) central venous access?
Authors: Keir Amy , Giesinger Regan , Dunn Michael
Published: August 2014

In this evidenced‐based review, we examine the current available literature to help answer the question ‘In neonates requiring long‐term central access [patient], does removal of the umbilical venous catheter (UVC) on days 5–7 and replacement with a peripherally inserted central catheter line [intervention] compared with leaving the UVC in situ [comparison] reduce rates of central line‐associated bloodstream infections [outcome]?’
Diversity of bladed Bangiales (Rhodophyta) in western Mediterranean: recognition of the genus Themis and descriptions of T. ballesterosii sp. nov., T. iberica sp. nov., and Pyropia parva sp. nov.
Authors: Sánchez Noemí , Vergés Alba , Peteiro César , Sutherland Judith E. , Brodie Juliet
Published: August 2014

The diversity of the bladed species of the red algal order Bangiales from the Iberian Mediterranean shores has been reassessed after a detailed study of this region. Prior to this study, 11 bladed species of Bangiales had been reported from Mediterranean waters: Porphyra atropurpurea, P. cordata, P. coriacea, P. dioica, P. linearis, P. purpurea, P. umbilicalis, Pyropia leucosticta, Pyropia koreana (as P. olivii), Py. elongata (as P. rosengurttii) and Py. suborbiculata. A combined analysis of the nuclear nSSU and the plastid rbcL genes together with detailed morphological studies has confirmed the presence of species within the genera Porphyra and Pyropia and also revealed a third, undescribed genus, Themis gen. nov. Porphyra linearis, Pyropia elongata and the introduced Pyropia koreana had been previously listed for the Mediterranean and were recorded in this study. An additional four species, including the introduced Pyropia suborbiculata and three new species: Pyropia parva sp. nov., Themis ballesterosii sp. nov., and Themis iberica sp. nov. were also observed. Hence, most of the Porphyra species traditionally reported along these shores were not reported in this survey. This new floristic Bangiales composition confirms the importance of the Mediterranean basin as a hotspot for biodiversity, possible endemics of ancient origin and high proportion of introductions. Our data also continue to confirm the extent of Bangiales diversity at regional and worldwide levels.
Pharmacokinetic modeling and Monte Carlo simulation of ondansetron following oral administration in dogs
Authors: Baek I.‐H. , Lee B.‐Y. , Kang J. , Kwon K.‐I.
Published: August 2014

Ondansetron is a potent antiemetic drug that has been commonly used to treat acute and chemotherapy‐induced nausea and vomiting (CINV) in dogs. The aim of this study was to perform a pharmacokinetic analysis of ondansetron in dogs following oral administration of a single dose. A single 8‐mg oral dose of ondansetron (Zofran®) was administered to beagles (n = 18), and the plasma concentrations of ondansetron were measured by liquid chromatography‐tandem mass spectrometry. The data were analyzed by modeling approaches using ADAPT5, and model discrimination was determined by the likelihood‐ratio test. The peak plasma concentration (Cmax) was 11.5 ± 10.0 ng/mL at 1.1 ± 0.8 h. The area under the plasma concentration vs. time curve from time zero to the last measurable concentration was 15.9 ± 14.7 ng·h/mL, and the half‐life calculated from the terminal phase was 1.3 ± 0.7 h. The interindividual variability of the pharmacokinetic parameters was high (coefficient of variation > 44.1%), and the one‐compartment model described the pharmacokinetics of ondansetron well. The estimated plasma concentration range of the usual empirical dose from the Monte Carlo simulation was 0.1–13.2 ng/mL. These findings will facilitate determination of the optimal dose regimen for dogs with CINV.
Brain penetration of emodepside is increased in P‐glycoprotein‐deficient mice and leads to neurotoxicosis
Authors: Elmshäuser S. , Straehle L. C. , Kranz J. , Krebber R. , Geyer J.
Published: August 2014

The antiparasitic drug emodepside (EMO) is a substrate of the P‐glycoprotein multidrug efflux carrier (P‐gp; syn. MDR1, ABCB1), which has an important function in protecting the brain from potentially toxic compounds by functional drug efflux at the blood–brain barrier (BBB). Many dogs of the Collie breed and even dogs of many other breeds have a loss‐of‐function 4‐bp deletion mutation in the MDR1 gene. In these dogs, brain penetration of many P‐gp‐transported drugs is increased and so their therapeutic usage is restricted. To elucidate the role of P‐gp at the BBB for the brain penetration of EMO, we applied EMO at 1 mg/kg to mdr1‐deficient (PGPmut) and mdr1‐intact (PGPWT) CF1 mice. Whereas in the brain of the PGPWT mice, EMO was below the detection level of 10 ng/g, its concentration was at 43.7 ng/g in the PGPmut mice. Furthermore, appearance of neurological toxicity was analyzed in these mice after application of 1 mg/kg EMO using a rotarod setup. In all PGPmut mice, but not in the PGPWT mice, the walking performance on the rotarod was impaired by EMO with clear differences in the degree and duration of neurological toxicity. Some of the mice were completely unable to walk on the rotarod already at 2 h after drug application and showed long‐lasting ataxia over >24 h. Others even showed significantly reduced walking performance, but completely recovered within 1 day. In conclusion, P‐gp restricts brain penetration of EMO and prevents neurological toxicity of this drug in mice.
Direct regulation of the pefI‐srgC operon encoding the Rck invasin by the quorum‐sensing regulator SdiA in Salmonella Typhimurium
Authors: Abed Nadia , Grépinet Olivier , Canepa Sylvie , Hurtado‐Escobar Genaro A. , Guichard Nolwenn , Wiedemann Agnès , Velge Philippe , Virlogeux‐Payant Isabelle
Published: August 2014

One important step for the pathogenesis of Salmonella is its ability to penetrate host cells. Recently, a new entry system involving the outer membrane protein Rck has been characterized. Previous studies have shown that the pefI‐srgC locus, which contains rck, was regulated by the temperature and SdiA, the transcriptional regulator of quorum sensing in Salmonella. To decipher the regulation of rck by SdiA, we first confirmed the operon organization of the pefI‐srgC locus. Using plasmid‐based transcriptional fusions, we showed that only the predicted distal promoter upstream of pefI, PefIP2, displays an SdiA‐ and acyl‐homoserine lactones‐dependent activity while the predicted proximal PefIP1 promoter exhibits a very low activity independent on SdiA in our culture conditions. A direct and specific interaction of SdiA with this PefIP2 region was identified using electrophoretic mobility shift assays and surface plasmon resonance studies. We also observed that Rck expression is negatively regulated by the nucleoid‐associated H‐NS protein at both 25°C and 37°C. This work is the first demonstration of a direct regulation of genes by SdiA in Salmonella and will help further studies designed to identify environmental conditions required for Rck expression and consequently contribute to better characterize the role of this invasin in vivo.
Salmonella acquires ferrous iron from haemophagocytic macrophages
Authors: Nagy Toni A. , Moreland Sarah M. , Detweiler Corrella S.
Published: August 2014

Bacteria harbour both ferrous and ferric iron transporters. We now report that infection of macrophages and mice with a Salmonella enterica Typhimurium strain containing an inactivated feoB‐encoded ferrous iron transporter results in increased bacterial replication, compared to infection with wild type. Inactivation of other cation transporters, SitABCD or MntH, did not increase bacterial replication. The feoB mutant strain does not have an intrinsically faster growth rate. Instead, increased replication correlated with increased expression in macrophages of the fepB‐encoded bacterial ferric iron transporter and also required siderophores, which capture ferric iron. Co‐infection of mice with wild type and a feoB mutant strain yielded a different outcome: FeoB is clearly required for tissue colonization. In co‐infected primary mouse macrophages, FeoB is required for S. Typhimurium replication if the macrophages were IFNγ treated and contain phagocytosed erythrocytes, a model for haemophagocytosis. Haemophagocytes are macrophages that have engulfed erythrocytes and/or leucocytes and can harbour Salmonella in mice. These observations suggest that Salmonella acquires ferrous iron from haemophagocytic macrophages.
Characteristics of Unselected High‐Burden Premature Ventricular Contraction Patients
Authors: YANG JINGKUN , DUDUM RAMZI , MANDYAM MALA C. , MARCUS GREGORY M.
Published: August 2014

Background

High‐burden premature ventricular contractions (PVCs) may be an important determinant of heart failure (HF) in patients presenting for PVC ablation. The prevalence and characteristics of high‐burden PVC patients outside this setting remain unknown. We, therefore, sought to determine predictors of high‐burden PVCs and, among high‐burden PVC patients, predictors of HF.

Methods

We identified all patients undergoing a 24–48‐hour Holter study showing at least 20% PVCs between 2005 and 2013 at the University of California, San Francisco. Three time‐matched controls undergoing Holter monitoring were selected for each high‐burden PVC patient. Medical records were reviewed and test characteristics of PVC counts from 12‐lead electrocardiograms (ECG) as predictors of high‐burden PVC Holters were analyzed.

Results

Among 5,091 participants, 66 (1.3%) exhibited at least 20% PVCs. After multivariate adjustment, high‐burden PVC patients had a three‐fold greater odds of HF (odds ratio [OR] 3.15; 95% confidence interval [CI] 1.28–6.50; P = 0.005) and 10‐fold greater odds of having a first‐degree family member with sudden death (OR 9.97; 95% CI 1.78–60.8; P = 0.011). The C‐statistic for the number of PVCs on 12‐lead electrocardiogram as a predictor of high‐burden PVCs was 0.7949. Among high‐burden PVC patients, HF was associated with a history of coronary artery bypass grafting (OR 11.76; 95% CI 1.30–106.49; P = 0.028).

Conclusion

Among all undergoing Holter monitoring, 1.3% exhibited high‐burden PVCs, a phenomenon associated with HF and a first‐degree family history of sudden death. In an analysis restricted to high‐burden PVC patients, a history of coronary artery bypass grafting was a predictor of HF.
Intranasal oxytocin attenuates the human acoustic startle response independent of emotional modulation
Authors: Ellenbogen Mark A. , Linnen Anne‐Marie , Cardoso Christopher , Joober Ridha
Published: August 2014

Oxytocin promotes social affiliation in humans. However, the mechanisms underlying this phenomenon require further elucidation. The present study investigated the influence of intranasal oxytocin on basic emotional processing in men and women, using an emotion‐modulated startle response paradigm. Eighty‐four participants self‐administered 24 IU of intranasal oxytocin or saline and completed an assessment of the acoustic startle reflex, using electromyography (EMG), with varying emotional foregrounds. Oxytocin had no impact on the affective modulation of the startle eye blink response, but significantly diminished the acoustic startle reflex irrespective of the emotional foreground. The results suggest that oxytocin facilitates prosocial behavior, in part, by attenuating basic physiological arousal. The dampening effect of oxytocin on EMG startle could possibly be used as an inexpensive marker of oxytocin's effect on limbic brain circuits.
Increased transfusion‐free survival following auxiliary pig liver xenotransplantation
Authors: Yeh Heidi , Machaidze Zurab , Wamala Isaac , Fraser James W. , Navarro‐Alvarez Nalu , Kim Karen , Schuetz Christian , Shi Shuai , Zhu Alexander , Hertl Martin , Elias Nahel , Farkash Evan A. , Vagefi Parsia A. , Varma Manish , Smith Rex Neal , Robson Simon C. , Van Cott Elizabeth M. , Sachs David H. , Markmann James F.
Published: August 2014

Background

Pig to baboon liver xenotransplantation typically results in severe thrombocytopenia and coagulation disturbances, culminating in death from hemorrhage within 9 days, in spite of continuous transfusions. We studied the contribution of anticoagulant production and clotting pathway deficiencies to fatal bleeding in baboon recipients of porcine livers.

Methods

By transplanting liver xenografts from α1,3‐galactosyltransferase gene‐knockout (GalT‐KO) miniature swine donors into baboons as auxiliary organs, leaving the native liver in place, we provided the full spectrum of primate clotting factors and allowed in vivo mixing of porcine and primate coagulation systems.

Results

Recipients of auxiliary liver xenografts develop severe thrombocytopenia, comparable to recipients of conventional orthotopic liver xenografts and consistent with hepatic xenograft sequestration. However, baboons with both pig and native livers do not exhibit clinical signs of bleeding and maintain stable blood counts without transfusion for up to 8 consecutive days post‐transplantation. Instead, recipients of auxiliary liver xenografts undergo graft failure or die of sepsis, associated with thrombotic microangiopathy in the xenograft, but not the native liver.

Conclusion

Our data indicate that massive hemorrhage in the setting of liver xenotransplantation might be avoided by supplementation with primate clotting components. However, coagulation competent hepatic xenograft recipients may be predisposed to graft loss related to small vessel thrombosis and ischemic necrosis.
Integration of High Performance Power Systems (HIPPS) Into Vision 21
Authors: Robson Fred L. , Ruby John D. , Seery Daniel J.
Published: August 2014

The U.S. Department of Energy/Federal Energy Technology Center (DOE/FETC)-sponsored High Performance Power Systems (HIPPS) program headed by United Technologies Research Center has identified coal-based combined-cycle power systems using advanced technology gas turbines that could operate at efficiencies approaching 55% (HHV). The HIPPS uses a High Temperature Advanced Furnace (HITAF) to preheat combustion turbine air. The HITAF’s metallic air heaters include a radiator section located in the furnace slagging zone and a convection section located in the downstream portion. The compressor discharge air is heated to 925 C – 1150 C. Additional heat for the turbine, if required in the cycle, is added by special low-NOx gas-fired combustors. The HITAF design has been successfully tested at the desired temperatures for short durations at the Energy and Environmental Research Center, Grand Forks, ND, with tests continuing to expand the systems experience and capabilities.

The HIPPS concept with its HITAF advanced air heater are valuable technology candidates for integration into Vision 21, the DoE’s evolving plan to utilize coal and other fossil fuels in energy complexes producing power, chemicals, process heat and other byproducts. For example, the HIPPS would be combined with high temperature fuel cells, e.g., the solid oxide fuel cell (SOFC), resulting in power systems having overall electrical efficiencies greater than 60% (HHV) with 50% or more of the energy input from coal. These power plants would have near zero emissions with a goal for power costs 10% below current coal-fired systems. Emissions of CO2, an important greenhouse gas, will be drastically reduced by the higher efficiencies of HIPPS cycles.

Very important from a power and coproduction market viewpoint, HIPPS can be an attractive repowering technology.

This will allow Vision 21 technology to be used in those plants that seek to continue using coal and other alternative solid fuels to capture the economic benefits of their low energy costs. Here, HIPPS adds high efficiency; increased capacity; load following and dispatching flexibility, as well as important environmental benefits to sites having existing fuel and transmission infrastructure.
Performance Seeking Control of Regenerative Gas Turbine Engines
Authors: Sugiyama Nanahisa
Published: August 2014

A Performance Seeking Control (PSC) can realize the operations advantageous enough to accomplish the economy, safety, engine life, and environmental issues by reducing the control margin to the extremity together with selection of the control variables so that various kinds of parameters will be minimized or maximized. This paper describes the results obtained from the simulation study concerning the PSC aiming at the efficiency enhancement, power improvement, and longer engine life of a two-spool regenerative gas turbine engine having two control variables. By constructing the dynamic simulation of the engine, steady-state characteristics and dynamic characteristics are derived; then, a PSC system is designed and evaluated. It is concluded that the PSC for the gas turbine of this type can be realized by the turbine inlet temperature control.
Implementation of a Multivariable Control
Authors: Larkin Louis J. , Philpott James
Published: August 2014

A multivariable control (MVC) was designed and implemented for the Joint Technology Demonstrator Engine (JTDE) XTE65-2. The engine control system utilized an existing MC68000 processor that used fixed point ADA for its programming language and was limited in throughput and memory. A canonical formulation for the MVC compensator was used to minimize memory and calculation load on the processor. Use of this formulation resulted in a number of numerical difficulties. This paper relates the issues associated with the implementation of a MVC in this environment, and some approaches to solve these difficulties.
Nonlinear Model Predictive Control Experiments on a Laboratory Gas Turbine Installation
Authors: van Essen H. A. , de Lange H. C.
Published: August 2014

Results on the feasibility and benefits of model based predictive control applied to a gas turbine are presented. For a laboratory gas turbine installation, the required dynamic simulation model and the real-time (nonlinear) Model Predictive Control (MPC) implementation are discussed. Results on both model validation and control performance are presented. We applied a nonlinear MPC configuration to control the laboratory gas turbine installation and succeeded in a real-time implementation. Although the available computation time for prediction and optimization of the model limits the sample time, the advantages of MPC, i.e. constraint handling, and anticipation to future (set-point) changes are fully reached, and the control performance is good. Special attention is paid to the performance of the applied filter that compensates for inevitable mismatches between model and process measurements. In general, the opportunities of model based control of turbomachinery are promising.
Closed Loop Minimization of NOx Emissions in a Gas Turbine
Authors: Rajamani Ravi , Goodman George , Bolton John , Joshi Narendra , Hook Rick , Kress Eric , Barrow Bill
Published: August 2014

This paper describes a system for minimizing NOx emissions in gas turbines. The system uses an optimization technique implemented on a portable computer. No hardware changes are necessary in the combustion system. The system was developed for an LM6000 Dry Low Emissions (DLE) engine. However, it can be applied across the board on any LM series DLE engine manufactured by the Industrial Aero-derivatives (IAD) division of GE Power Systems (GEPS).
Predicting the Deterministic Effects of Combustion Gas Environments on the Stress-Rupture Life of Silicon Nitride Turbine Components
Authors: Strangman Thomas E. , Schenk Bjoern
Published: August 2014

Silicon nitride ceramic turbine components are under intensive development by Honeywell International Inc. to enable a new generation of higher power density engines. Auxiliary power units and industrial engines are frequently used in high salt ingestion (e.g., coastal airport) operating environments, which can accelerate turbine component degradation. In order to better recognize and avoid severe degradation conditions associated with hot corrosion and oxidation of ceramic components, Honeywell developed the CERSRL code to predict the effects of duty cycle, environmental, and statistical scatter effects on tensile strength and stress-rupture lives. Predicted component life is dependent upon engine design (stress, temperature, pressure, fuel/air ratio, gas velocity, and inlet air filtration), mission usage (fuel sulfur content, location [salt in the air], and times at duty cycle power points), and material system parameters (Weibull modulus, characteristic strength, crack growth behavior, and coating [if any]). For a laboratory air oxidation environment and a specified probability of failure, the stress for rupture can be expressed as a function of a Larson-Miller Parameter (i.e., a function of temperature and rupture life).

Preliminary analyses indicate that the hot corrosion and oxidation resistance of silicon nitride materials, such as NT154 and AS800, is adequate for Honeywell’s initial engine applications. Inlet air filtration and protective coatings may be required to achieve required ceramic component lives in more aggressive environments.
Investigation of Cycle-to-Cycle Variability in an Unstable Gas Turbine Combustor
Authors: Lieuwen Tim C. , Zinn Ben T.
Published: August 2014

This paper describes an experimental and theoretical investigation of the processes controlling the characteristics of limit cycle oscillations in an unstable gas turbine combustor. Specifically, this paper describes an analysis of the cycle-to-cycle variations in the phase of the oscillating pressure during an instability. It is shown that the phase of the combustor pressure oscillations continuously drifts in a predominantly irregular manner. It is also shown that this phase drift may primarily be caused by random processes (i.e., noise) and, thus, may not reflect any of the underlying dynamics of the instability. Finally, it is shown that deterministic factors appear to have a small affect on the phase variability that manifests itself as slow, approximately 1.4 Hz oscillation of the phase. It is concluded that analysis of “steady state” limit cycle pressure data may not provide the desired information about the nonlinear processes controlling the system’s dynamics because of the affects of background noise.
Field Demonstration of a 1.5 MW Industrial Gas Turbine With a Low Emissions Catalytic Combustion System
Authors: Yee David K. , Lundberg Kare , Weakley Chris K.
Published: August 2014

An electric utility grid connected test facility has been established at Silicon Valley Power (SVP) in Santa Clara, California to validate the reliability, availability, maintainability and durability (RAMD) of a commercial-ready catalytic combustor system (XONON). Installed in the Silicon Valley Test Facility (SVTF) is a 1.5MW Kawasaki M1A-13A gas turbine fitted with a catalytic combustor. The gas turbine package is controlled by a Woodward MicroNet control system. The combustor utilizes a two stage lean premix preburner system to obtain the required catalyst inlet temperatures and low NOx over the operating load range. The fuel-air mixer incorporates counter rotating swirlers to mix the catalyst fuel and air to achieve the desired uniformity. The patented catalyst design is composed of specially coated metal foils. Overall engine performance was measured and the emissions were continuously monitored. As of December 1999, emissions of NOx < 2.5 ppmv and CO and UHC < 6 ppmv have been maintained at 100% load for over 3700 hours of operation on the utility grid. The turbine continues to operate 24 hours a day, 7 days per week with commercial levels of unit availability.
Velocity Measurements in a Combustor Undergoing Limit-Cycle Pressure Oscillations
Authors: Li J. , Acharya S.
Published: August 2014

Velocity measurements are reported in a swirl-stabilized spray combustor undergoing limit cycle pressure oscillations. The pressure-oscillations are a manifestation of the thermo-acoustic instability in the combustor (at 200Hz), and the goal of the present work is to understand the flow in a combustor with strong pressure oscillations. A second goal of the work is to provide data for the CFD modeling of self-excited combustion. The measurements have been made with a LDV for both the non-reacting case and the reacting flow case, and include velocity information for both the gas phase (with titanium dioxide seeding) and the droplet phase (no seeding).

Measurements reveal substantial increases in the axial and tangential velocities under reacting flow conditions. The swirl-induced recirculation zone is much stronger (higher negative velocities) with combustion. Unburnt droplets are observed as far downstream as Z/Ro = 0.72 (nearly 5cm from the injection nozzle). Significant enhancements in the turbulence levels are noted in the presence of combustion, and these are partly attributed to the thermoacoustic instability and strong pressure oscillations.
Industrial RB211 DLE Gas Turbine Combustion Update
Authors: Willis Jeffrey D. , Moran A. John
Published: August 2014

Industrial gas turbines have universally had problems with combustion amplified pressure oscillations (combustion instability or noise) in premix lean burn combustors. Reference 1 issued by General Electric is a particularly good report. Under specific conditions a resonant frequency achieves sufficient amplitude to cause severe damage to the combustor. As the emissions are reduced to lower levels, by achieving better uniformity of fuel and air distribution and a larger percentage of the air is used in the combustion process, then these amplitudes have the potential to become greater especially at high pressure ratios. Small changes in either ambient conditions or fuel quality appear to cause noise amplitudes to become unacceptable.
Experimental and Numerical Investigation of a Planar Combustor Sector at Realistic Operating Conditions
Authors: Behrendt Thomas , Carl Martin , Fleing Christian , Frodermann Matthias , Heinze Johannes , Hassa Christoph , Meier Ulrich , Wolff-Gaßmann Dagmar , Hohmann Stefan , Zarzalis Nikolaos
Published: August 2014

Results of an ongoing collaboration between the engine manufacturer MTU and the German aerospace research center DLR on the NOx reduction potential of conventional combustors are reported. A program comprising optical sector combustor measurements at 1, 6 and 15 bars and CFD calculations is carried out. The aims are to gather information in the combustor at realistic operating conditions, to understand the differences between the sector flow field and data from tubular combustors, to verify the used CFD and to discover the benefits and limitations of the applied optical diagnostics. Selected results of measurement and calculation of the isothermal flow and of measurements at 6 bars and 700 K at a rich-lean and overall lean AFR are reported. The used measurement techniques were LDA, PDA, Mie scattering on kerosene, Quantitative Light Scattering, OH* Chemiluminescence and LIF on OH. The measurements were able to confirm the intended quick and homogeneous mixing of the three staggered rows of secondary air jets.
Coupled and Uncoupled CFD Prediction of the Characteristics of Jets From Combustor Air Admission Ports
Authors: McGuirk J. J. , Spencer A.
Published: August 2014

The paper focusses attention on alternative approaches for treating the coupling between the flow in the annulus supply ducts and the jets which enter combustor primary and dilution zones through air admission ports. Traditionally CFD predictions of combustor flows have modeled this in a very weakly-coupled manner, with the port flow conditions being derived from 1D empirical correlations and used as boundary conditions for an internal-flow-only combustor CFD prediction. Recent work by the authors and others has introduced the viewpoint that fully-coupled external-annulus/internal-combustor predictions is the way forward. Experimental data is gathered in the present work to quantify the strength of the interaction between annulus and core flows, which ultimately determines the jet characteristics at port exit. These data are then used to illustrate the improvement in the prediction of port exit jet characteristics which is obtained by adopting fully-coupled calculations compared to the internal-flow-only approach. As a final demonstration of the importance of a fully coupled approach, isothermal calculations are presented for a single sector generic annular combustor. These show that quite different primary zone flow patterns are obtained from the two approaches, leading to considerable differences in the overall mixing pattern at combustor exit.
Reaction Mechanisms for Methane Ignition
Authors: Li S. C. , Williams F. A.
Published: August 2014

To help understand how methane ignition occurs in gas turbines, dual-fuel diesel engines and other combustion devices, the present study addresses reaction mechanisms with the objective of predicting autoignition times for temperatures between 1000 K and 2000 K, pressures between 1 bar and 150 bar and equivalence ratio between 0.4 and 3. It extends our previous methane flame chemistry and refines earlier methane ignition work. In addition to a detailed mechanism, short mechanisms are presented that retain essential features of the detailed mechanism. The detailed mechanism consists of 127 elementary reactions among 31 species and results in 9 intermediate species being most important in autoignition, namely, CH3, OH, HO2, H2O2, CH2O, CHO, CH3O, H, O. Below 1300 K the last 3 of these are unimportant, but above 1400 K all are significant. To further simplify the computation, systematically reduced chemistry is developed, and an analytical solution for ignition delay times is obtained in the low-temperature range. For most fuels, a single Arrhenius fit for the ignition delay is adequate, but for hydrogen the temperature sensitivity becomes stronger at low temperatures. The present study predicts that, contrary to hydrogen, for methane the temperature sensitivity of the autoignition delay becomes stronger at high temperatures, above 1400 K, and weaker at low temperatures, below 1300 K. Predictions are in good agreement with shock-tube experiments. The results may be employed to estimate ignition delay times in practical combustors.
Natural Gas Decarbonization to Reduce CO2 Emission From Combined Cycles: Part B — Steam-Methane Reforming
Authors: Lozza Giovanni , Chiesa Paolo
Published: August 2014

This paper discusses novel schemes of combined cycle, where natural gas is chemically treated to remove carbon, rather than being directly used as fuel. Carbon conversion to CO2 is achieved before gas turbine combustion. The first part of the paper discussed plant configurations based on natural gas partial oxidation to produce carbon monoxide, converted to carbon dioxide by shift reaction and therefore separated from the fuel gas. The second part will address methane reforming as a starting reaction to achieve the same goal. Plant configuration and performance differs from previous case because reforming is endothermic and requires high temperature heat and low operating pressure to obtain an elevated carbon conversion.

The performance estimation shows that the reformer configuration has a lower efficiency and power output than the systems addressed in Part A. To improve the results, a reheat gas turbine can be used, with different characteristics from commercial machines. The thermodynamic efficiency of the systems of the two papers is compared by an exergetic analysis.

The economic performance of natural gas fired power plants including CO2 sequestration are therefore addressed, finding a superiority of the partial oxidation system with chemical absorption. The additional cost of the kWh, due to the ability of CO2 capturing, can be estimated at about 13–14 mill$/kWh.
An Ericsson Cycle GT Design by LNG Cryogenic Heat Utilization
Authors: Hanawa Kirk
Published: August 2014

In many LNG receiving terminals worldwide, the cryogenic heat of imported LNG which was liquefied by using 10% energy of natural gas supply1), 2), has been wasted into the sea water mainly through heat exchangers like ORVs (Open Rack Vaporizer)3). This cryogenic heat of 110 K (-256 F) class is considered, however, as an excellent energy source to apply thermodynamic cycles. Several literature, accordingly, are found to improve such high-grade energy potential of LNG regasification process as a low temperature sink, combining with fired heater at 1,100 K (1520 F) class or GT main exhaust gas at 700 K (800 F) class as a high temperature source, through Brayton and Rankine cycles5),6),7),8),9).

This paper presents a typical example of closed “Ericsson” cycle which has the minimum cycle temperature of 157 K (-176 F) from LNG cryogenic heat and the maximum of 550 K (531 F) from the partial HRSG exit heat mixed with the partial GT exit gas. This closed gas turbine, from viewpoints of minor modification to existing power plants and no energy impacts for high temperature source, which would be better than the above-described idea, is able to offer 35% thermal efficiency. And it is recognized that this system would be superior to existing cryogenic generation systems of 20% class operated by Rankine Cycle.
Power Plants Up-Rating Benefit From Technology Advancements: A Case Study
Authors: McCue Robert , von Rappard Axel W.
Published: August 2014

Life cycle considerations, Reliability / Availability and Maintainability (RAM) experiences, as well as performance improvements, drive power producers not only to plan new power plants but also to upgrade older ones. The main driver, however, is competitiveness and this means cost of electricity for the end users and equipment availability for the shareholders. An up-rating is attractive if you can increase performance and reduce failure rate and thereby operating risks.

The first part of this paper describes the actual configuration of a combined cycle plant and the operating experience over the past three to five years. This refers to performance parameters — power and heat rate — as well as to RAM performance. Up-rating shows normally an advantage compared to new equipment concerning reliability, availability and maintainability. A cooperation of the parties involved — power producer and engine manufacturer (OEM) — is necessary, when all above-mentioned parameters are considered. The up-rating can improve the performance (power and heat rate), can keep reliability and availability at high values and can influence the maintainability positively.

The second part addresses the evaluation and the stepwise implementation of the solution and the summary of the results. Different power producers and ABB have worked closely together to evaluate the options and to develop the best solution. The conclusions will show how important the power producer / OEM relationship is when such upgrades are implemented and the results are measured. Due to the multitude of interfaces associated with gas turbine power plant upgrades, good co-operation is essential. This case study, is also the result of solutions developed with several power producers.
World’s First LM5000 to LM6000 Cogeneration Plant Repowering
Authors: McCarrick Michael T. , Rosencrance Robert K.
Published: August 2014

With the introduction of GE’s latest and most efficient gas turbine, the LM6000 in 1992, and the end of production of GE’s LM5000 gas turbine in 1997, the concept of repowering aging LM5000 gas turbine powered cogeneration plants with LM6000 gas turbines was an idea that most LM5000 owners and operators dreamed about. The LM6000 is an ideal replacement for the LM5000 as they both have nearly the same mass flow and exhaust gas temperature (critical for Heat Recovery Steam Generator (HRSG) compatibility), are about the same physical weight and dimensions, and can be operated in the same power range. Also, as the LM6000 is a current production model, it has more readily available spare gas turbines and turbine parts, has a much improved heat rate, lower emissions level, and has an option (SPRINT), for added power. In December 1999, the UAE Oildale Energy Facility became the first plant to operate with a newly installed LM6000 in its former LM5000 package. (This March the second LM5000 to LM6000 repowering was completed for Calpine Corporation at their Greenleaf #1 Cogeneration Plant in Yuba City, CA.) Energy Services, Inc., GE’s authorized LM6000 repowering OEM, designed, engineered and project managed the repowering.

This paper will present the reasons UAE decided to repower; discuss the technical challenges encountered with, and modifications made to, the GEC ELM-150 cogeneration plant to accommodate the LM6000; review the schedule; and provide the economic benefits of the improved heat rate and reliability of the LM6000.
Secondary Flow Measurements in a Turbine Passage With Endwall Flow Modification
Authors: Aunapu Nicole V. , Volino Ralph J. , Flack Karen A. , Stoddard Ryan M.
Published: August 2014

A flow modification technique is introduced in an attempt to allow increased turbine inlet temperatures. A large-scale two half-blade cascade simulator is used to model the secondary flow between two adjacent turbine blades. Various flow visualization techniques and measurements are used to verify that the test section replicates the flow of an actual turbine engine. Two techniques are employed to modify the endwall secondary flow, specifically the path of the passage vortex. Six endwall jets are installed at a location downstream of the saddle point near the leading edge of the pressure side blade. These wall jets are found to be ineffective in diverting the path of the passage vortex. The second technique utilizes a row of 12 endwall jets whose positions along the centerline of the passage are based on results from an optimized boundary layer fence. The row of jets successfully diverts the path of the passage vortex and decreases its effect on the suction side blade. This can be expected to increase the effectiveness of film cooling in that area. The row of jets increases the aerodynamic losses in the passage, however. Secondary flow measurements are presented showing the development of the endwall flow, both with and without modification.