bluuebunny/crossref_metadata_2025 huggingface dataset:
Crime, Media and Moral Panic in an Expanding European Union
Authors: MAWBY ROB C. , GISBY WILLIAM
Published: November 2008

Abstract:In the latest phase of European Union enlargement Bulgaria and Romania were admitted to EU membership on 1 January 2007. In the UK, media coverage of the accession process focused on the potential movement of large numbers of people from Eastern to Western European states; a particular focus was the crime risk associated with enlargement. This article examines how newspapers reported the perceived crime threats and assesses the extent to which the concerns can be understood as a moral panic. The article confirms the contemporary utility of moral panic analysis, albeit with some flexibility to reflect the modern media landscape.
Observed Leadership Potential of Personnel in a Team Setting: Big Five traits and proximal factors as predictors
Authors: Hirschfeld Robert R. , Jordan Mark H. , Thomas Christopher H. , Feild Hubert S.
Published: November 2008

The authors explored implications of Big Five traits and proximal factors for the observed leadership potential of personnel in newly formed teams. Big Five traits were designated as distal factors having indirect links to observed leadership potential via three proximal factors: individual perception of team cohesion, team‐oriented proactivity, and teamwork knowledge. Drawing from implicit personality theory, the authors introduced a team‐leader personality profile as a higher‐order construct for explaining covariation among extraversion, conscientiousness, and emotional stability. A structural analysis of data from 472 personnel supported hypothesized relationships. Specific findings included validation of a team‐leader personality profile and preliminary support for the measure of team‐oriented proactivity that was developed for this study. Implications of the various findings are discussed.
Assessing the Influence of Psychosocial and Career Mentoring on Organizational Attractiveness
Authors: Spitzmüller Christiane , Neumann Elke , Spitzmüller Matthias , Rubino Cristina , Keeton Kathryn E. , Sutton Meagan T. , Manzey Dietrich
Published: November 2008

Past research on mentoring in organizational settings has focused on psychosocial and career mentoring functions more senior employees provide to new hires. In this study, we examined whether the perceived quality of psychosocial and career functions of pre‐hire mentoring and realistic job previews (RJPs) provided to students through mentoring impact organizational attraction and potential applicants' intentions to pursue or accept jobs at their mentors' organization, and ultimately their acceptance of positions with their mentors' organization. We compared face‐to‐face mentoring with online mentoring. A field study was conducted (n=194 European graduate students). Findings indicate that the quality of psychosocial mentoring plays a larger role in organizational attraction and intentions to pursue jobs than the perceived level/quality of career mentoring functions, with RJPs functioning as a suppressor variable. Obtaining a job with the mentors' organization was related to career, but not to psychosocial mentoring functions or RJPs.
Effect of high intensity pulsed electric fields on enzymes and vitamins in bovine raw milk
Authors: RIENER JOERG , NOCI FRANCESCO , CRONIN DENIS A , MORGAN DESMOND J , LYNG JAMES G
Published: November 2008

Pulsed electric fields (PEF) were applied to fresh bovine raw milk using a laboratory‐scale continuous PEF system to study the impact on selected native enzyme activities and on vitamin degradation. The activities of protease, lipase, alkaline phosphatase and lactoperoxidase following PEF treatment at electric field strengths ranging from 15 to 35 kV/cm for treatment times of 12.5 µs to 75 µs were examined. Reductions in enzyme activity, even under the most severe conditions employed, were quite modest, amounting to 14%, 37% and 29% for lipase, protease and alkaline phosphatase, respectively, while the activity of lactoperoxidase remained unchanged. The PEF treatment had no effect on the levels of thiamin, riboflavin, retinol and α‐tocopherol in the milk.
A novel reciprocal and biphasic relationship between membrane cholesterol and β‐secretase activity in SH‐SY5Y cells and in human platelets
Authors: Liu Wei Wei , Todd Stephen , Coulson David T. R. , Brent Irvine G. , Peter Passmore A. , McGuinness Bernadette , McConville Maeve , Craig David , Johnston Janet A.
Published: November 2008

Research into the cause of Alzheimer’s disease (AD) has identified strong connections to cholesterol. Cholesterol and cholesterol esters can modulate amyloid precursor protein (APP) processing, thus altering production of the Aβ peptides that deposit in cortical amyloid plaques. Processing depends on the encounter between APP and cellular secretases, and is thus subject to the influence of cholesterol‐dependent factors including protein trafficking, and distribution between membrane subdomains. We have directly investigated endogenous membrane β‐secretase activity in the presence of a range of membrane cholesterol levels in SH‐SY5Y human neuroblastoma cells and human platelets. Membrane cholesterol significantly influenced membrane β‐secretase activity in a biphasic manner, with positive correlations at higher membrane cholesterol levels, and negative correlations at lower membrane cholesterol levels. Platelets from individuals with AD or mild cognitive impairment (n = 172) were significantly more likely to lie within the negative correlation zone than control platelets (n = 171). Pharmacological inhibition of SH‐SY5Y β‐secretase activity resulted in increased membrane cholesterol levels. Our findings are consistent with the existence of a homeostatic feedback loop between membrane cholesterol level and membrane β‐secretase activity, and suggest that this regulatory mechanism is disrupted in platelets from individuals with cognitive impairment.
Morphine and HIV‐Tat increase microglial‐free radical production and oxidative stress: possible role in cytokine regulation
Authors: Turchan‐Cholewo Jadwiga , Dimayuga Filomena O. , Gupta Sunita , Keller Jeffrey N. , Knapp Pamela E. , Hauser Kurt F. , Bruce‐Keller Annadora J.
Published: November 2008

Opiate abuse alters the progression of human immunodeficiency virus and may increase the risk of neuroAIDS. As neuroAIDS is associated with altered microglial reactivity, the combined effects of human immunodeficiency virus‐Tat and morphine were determined in cultured microglia. Specifically, experiments determined the effects of Tat and morphine on microglial‐free radical production and oxidative stress, and on cytokine release. Data show that combined Tat and morphine cause early and synergistic increases in reactive oxygen species, with concomitant increases in protein oxidation. Furthermore, combined Tat and morphine, but not Tat or morphine alone, cause reversible decreases in proteasome activity. The effects of morphine on free radical production and oxidative stress are prevented by pre‐treatment with naloxone, illustrating the important role of opioid receptor activation in these phenomena. While Tat is well known to induce cytokine release from cultured microglia, morphine decreases Tat‐induced release of the cytokines tumor necrosis factor‐α and interleukin‐6, as well as the chemokine monocyte chemoattractant protein‐1 (MCP‐1). Finally, experiments using the reversible proteasome inhibitor MG115 show that temporary, non‐cytotoxic decreases in proteasome activity increase protein oxidation and decrease tumor necrosis factor‐α, interleukin‐6, and MCP‐1 release from microglia. Taken together, these data suggest that oxidative stress and proteasome inhibition may be involved in the immunomodulatory properties of opioid receptor activation in microglia.
Afamin is synthesized by cerebrovascular endothelial cells and mediates α‐tocopherol transport across an in vitro model of the blood–brain barrier
Authors: Kratzer Ingrid , Bernhart Eva , Wintersperger Andrea , Hammer Astrid , Waltl Sabine , Malle Ernst , Sperk Günther , Wietzorrek Georg , Dieplinger Hans , Sattler Wolfgang
Published: November 2008

α‐Tocopherol (αTocH), a member of the vitamin E family, is essential for normal neurological function. Despite the importance of αTocH transport into the CNS, transfer mechanisms across the blood–brain barrier (BBB) are not entirely clear. We here investigate whether afamin, a known αTocH‐binding protein, contributes to αTocH transport across an in vitro model of the BBB consisting of primary porcine brain capillary endothelial cells (BCEC) and basolaterally cultured astrocytoma cells. Exogenously added afamin had no adverse effects on BCEC viability or barrier function and was transported across BCEC Transwell cultures. Furthermore, αTocH transport across polarized BCEC cultures to astrocytoma cells is facilitated by afamin, though to a lesser extent than by high‐density lipoprotein‐mediated transport, an essential and in vivo operating αTocH import pathway at the cerebrovasculature. We also demonstrate that porcine BCEC endogenously synthesize afamin. In line with these in vitro findings, afamin was detected by immunohistochemistry in porcine, human postmortem, and mouse brain, where prominent staining was observed almost exclusively in the cerebrovasculature. The demonstration of afamin mRNA expression in isolated brain capillaries suggests that afamin might be a new family member of binding/transport proteins contributing to αTocH homeostasis at the BBB in vivo.
ANALYSIS OF NASRID POLYCHROME CARPENTRY AT THE HALL OF THE MEXUAR PALACE, ALHAMBRA COMPLEX (GRANADA, SPAIN), COMBINING MICROSCOPIC, CHROMATOGRAPHIC AND SPECTROSCOPIC METHODS*†
Authors: CARDELL C. , RODRIGUEZ‐SIMON L. , GUERRA I. , SANCHEZ‐NAVAS A.
Published: November 2008

The pigments, binders and execution techniques used by the Nasrids (1238–1492) to polychrome carpentry in the Hall of the Mexuar Palace at the Alhambra (Granada, Spain) were studied using optical microscopy, scanning electron microscopy with EDX analysis, selective staining techniques and gas chromatography – mass spectrometry. This pioneering investigation presents the first results of a research project devoted to filling gaps in the knowledge of Nasrid art, traditionally approached by stylistic studies. Moreover, it is essential for the polychromy conservation of the studied artworks, and will help to clarify historical and painting uncertainties in the Alhambra monument. The palette consists of a limited range of colours: white (lead‐base pigment), red (cinnabar and red lead), blue (lapis lazuli), black (carbon‐based) and false gold (golden tin). Tempera grassa was the painting technique identified. Two types of grounds were used: (i) gypsum in calligraphy decoration for the false gold technique, and (ii) synthetic minium in geometric drawings in carpentry. Organic insulating layers of linseed oil were used between paint strata. Artists applied synthetic minium to protect the wood (Juglans regia and conifer) against attack by xylophages. To lighten the surface darkened by this ground layer, powdered tin was added to achieve a metallic lustre.
Resolution of periodontal inflammation does not guarantee improved glycemic control in type 1 diabetic subjects
Authors: Tervonen Tellervo , Lamminsalo Sari , Hiltunen Liisa , Raunio Taina , Knuuttila Matti
Published: November 2008

Objective: The aim of this study was to find out if periodontal therapy has any effect on glycemic control of type 1 diabetes mellitus (DM).

Subjects and Methods: The periodontal health status of 65 type 1 diabetic subjects was assessed at the baseline and 8 weeks after completion of periodontal therapy. Glycemic control was assessed on both visits by measuring the percentage of glycosylated haemoglobin (GHbA1c). The change in HbA1c (ΔHbA1c) was assessed by using both a positive or negative change 0.5% and any change in HbA1c.

Results: The mean HbA1c level (±SD) of the whole study group was 8.6% (±1.5) at the baseline and 8.5% (±1.5) after treatment. Glycemic control improved during the study period in 23 subjects (35%) and worsened in 18 subjects (28%). Approximately 78% of the bleeding sites and 87% of the sites with probing depth 4 mm presented healing. ΔHbA1c associated significantly with baseline HbA1c but not with baseline periodontal health status or periodontal healing.

Conclusion: Regardless of a significant resolution of periodontal infection, a great majority of the subjects did not present any improvement in their glycemic control.
Dictyostelium Tom1 Participates to an Ancestral ESCRT‐0 Complex
Authors: Blanc Cédric , Charette Steve J. , Mattei Sara , Aubry Laurence , Smith Ewan W. , Cosson Pierre , Letourneur François
Published: November 2008

Sorting of ubiquitinated proteins to multivesicular bodies (MVBs) in mammalian cells relies on proteins with a Vps27/Hrs/STAM (VHS) domain. Here, we show that the amoeba Dictyostelium presents only one protein with a VHS domain: DdTom1. We demonstrate that the VHS domain of DdTom1 is followed by a Golgi‐localized, γ‐ear‐containing, ADP‐ribosylation‐factor‐binding and Tom1 (GAT) domain that binds ubiquitin, and by a non‐conserved C‐terminal domain that can recruit clathrin, EGFr pathway substrate 15 and tumor susceptibility gene 101, a component of the MVB biogenesis machinery [endosomal complexes required for transport (ESCRT) complexes]. Both VHS and GAT domains interact with phospholipids and therefore could ensure the recruitment of DdTom1 to endosomal membranes. We propose that DdTom1 participates in an ancestral ESCRT‐0 complex implicated in the sorting of ubiquitinated proteins into MVBs.
Epsin 1 is Involved in Recruitment of Ubiquitinated EGF Receptors into Clathrin‐Coated Pits
Authors: Kazazic Maja , Bertelsen Vibeke , Pedersen Ketil Winther , Vuong Tram Thu , Grandal Michael Vibo , Rødland Marianne Skeie , Traub Linton M. , Stang Espen , Madshus Inger Helene
Published: November 2008

Epsin consists of an epsin NH2‐terminal homology domain that promotes interaction with phospholipids, several AP‐2‐binding sites, two clathrin‐binding sequences and several Eps15 homology domain‐binding motifs. Epsin additionally possesses ubiquitin‐interacting motifs (UIMs) and has been demonstrated to bind ubiquitinated cargo. We therefore investigated whether epsin promoted clathrin‐mediated endocytosis of the ubiquitinated EGF receptor (EGFR). By immunoprecipitation, we found that epsin 1 interacted with ubiquitinated EGFR and that functional UIMs were essential for complex formation. Furthermore, RNA interference‐mediated knockdown of epsin 1 was found to inhibit internalization of the EGFR, while having no effect on endocytosis of the transferrin receptor. Additionally, upon knockdown of epsin 1, translocation of the EGFR to central parts of clathrin‐coated pits was inhibited. This supports the contention that epsin 1 promotes endocytosis of the ubiquitinated EGFR.
The Study of Proverbs in Anglo‐Saxon Literature: Recent Scholarship, Resources for Research, and the Future of the Field
Authors: Kramer Johanna
Published: November 2008

This article surveys the major developments in paremiology (the study of proverbs) in Anglo‐Saxon literature over the last fifteen years as well as the major research tools currently available for the study of medieval vernacular and Latin proverbs. Through this survey, I demonstrate that proverbs need to be read not only in light of the immediate context in which they appear, but also ‘in isolation.’ Studying the history and transmission of proverbs independent from their contextual uses can lead us to a more complete understanding of an individual author's interests, reading, education, and motivations for deplying a proverb. I begin by discussing the difficulties of defining precisely paremiological terminology. Then I give an overview of the most important achievements in proverb study more generally over the last century, with an emphasis on medieval paremiology. After reviewing the two most recent book‐length studies on Old English proverbial materials, I summarize individually most of the publications on Anglo‐Saxon proverbs that have appeared over the last fifteen years. A number of excellent print and digital resources, which I introduce to readers in this article, assist proverb scholars in their work. Finally, I suggest some future avenues for research with which Old English proverb study can significantly contribute to the larger field of Anglo‐Saxon studies.
The purine derivative PI‐55 blocks cytokinin action via receptor inhibition
Authors: Spíchal Lukáš , Werner Tomáš , Popa Igor , Riefler Michael , Schmülling Thomas , Strnad Miroslav
Published: November 2008

One of several potential approaches to study mechanisms of action of biologically active compounds is to develop their agonists and antagonists. In the present study, we report the identification of the first known molecule antagonizing the activity of the plant hormone cytokinin at the receptor level. This compound, 6‐(2‐hydroxy‐3‐methylbenzylamino)purine, designated PI‐55 in the present study, is structurally closely related to cytokinin 6‐benzylaminopurine, but substitutions at specific positions of the aromatic side chain strongly diminished its cytokinin activity and conferred antagonistic properties. PI‐55 competitively inhibited the binding of the natural ligand trans‐zeatin to the Arabidopsis cytokinin receptors cytokinin response 1 (CRE1)/Arabidopsis histidine kinase (AHK) 4 and AHK3 and repressed induction of the cytokinin response gene ARR5:GUS. Genetic analysis revealed that CRE1/AHK4 is the primary target of PI‐55. Cytokinin bioassays also demonstrated the anticytokinin effect of PI‐55 in several other species. Furthermore, we show that PI‐55 accelerated the germination of Arabidopsis seeds and promoted the root growth and formation of lateral roots, thus phenocopying the known consequences of a lowered cytokinin status and demonstrating its potential to inhibit cytokinin perception in planta. PI‐55 is the first example for the targeted development of a cytokinin antagonist and represents an initial step for the preparation of cytokinin antagonists with broad activity and reduced agonistic properties.
WOMEN'S UNION LEADERSHIP: CLOSING THE GENDER GAP
Authors: Kaminski Michelle , Yakura Elaine K.
Published: November 2008

Women comprise 44 percent of the labor movement, but a smaller percentage of union leaders. We discuss the importance of having a leadership that is representative of the membership, some of the differences between male and female leadership, and why the labor movement needs more women leaders. In order to promote women's leadership, we first discuss a four‐stage model of how union leaders develop: finding your voice, developing basic skills, figuring out the politics, and setting the agenda. We then add suggestions about what current union leaders can do to promote women's leadership at each of these four stages.
Spatial and Temporal Quantitative Analysis of Cell Division and Elongation Rate in Growing Wheat Leaves under Saline Conditions
Authors: Hu Yuncai , Schmidhalter Urs
Published: November 2008

Leaf growth in grasses is determined by the cell division and elongation rates, with the duration of cell elongation being one of the processes that is the most sensitive to salinity. Our objective was to investigate the distribution profiles of cell production, cell length and the duration of cell elongation in the growing zone of the wheat leaf during the steady growth phase. Plants were grown in loamy soil with or without 120 mmol/L NaCl in a growth chamber, and harvested at day 3 after leaf 4 emerged. Results show that the elongation rate of leaf 4 was reduced by 120 mmol/L NaCl during the steady growth phase. The distribution profile of the lengths of abaxial epidermal cells of leaf 4 during the steady growth stage shows a sigmoidal pattern along the leaf axis for both treatments. Although salinity did not affect or even increased the length of the epidermal cells in some locations in the growth zone compared to the control treatment, the final length of the epidermal cells was reduced by 14% at 120 mmol/L NaCl. Thus, we concluded that the observed reduction in the leaf elongation rate derived in part from the reduced cell division rate and either the shortened cell elongation zone or shortened duration of cell elongation. This suggests that more attention should be paid to the effects of salinity on those properties of cell production and the period of cell maturation that are related to the properties of cell wall.
Effects of Crop Development on the Emission of Volatiles in Leaves of Lycopersicon esculentum and Its Inhibitory Activity to Botrytis cinerea and Fusarium oxysporum
Authors: Zhang Peng‐Ying , Chen Kao‐Shan , He Pei‐Qing , Liu Sheng‐Hao , Jiang Wan‐Feng
Published: November 2008

Volatiles emitted from the leaves of Lycopersicon esculentum at the two‐, ten‐leaf and anthesis periods were collected by a gas absorbing method and analyzed by gas chromatography (GC)‐mass spectrometry. In total, 33 compounds of volatiles emitted from three developmental stage plants were separated and identified, and quantitatively analyzed by the internal standard addition method. All of the samples of volatile were found to be rich in monoterpenes and sesquiterpenes. β‐phellandrene and caryophyllene predominated in the volatiles of the leaves of plants at the two‐ and ten‐leaf stages. Furthermore, (E)‐2‐hexenal were the dominant components in the volatiles emitted from anthesis plants. The results of volatiles analyzed show that the compositions varied depending on the developmental stages. The volatiles emitted from crushed tomato leaves of plants at the anthesis stage had the most strongly inhibitory activity against the spore germination and hyphal growth of Botrytis cinerea and Fusarium oxysporum, followed by ten‐ and two‐leaf plants. However, the activity of volatiles, emitted from the leaves of plants at the two‐leaf stage, in inhibiting F. oxysporum was greater than B. cinerea.
Simple Sequence Repeat Analysis of Genetic Diversity in Primary Core Collection of Peach (Prunus persica)
Authors: Li Tian‐Hong , Li Yin‐Xia , Li Zi‐Chao , Zhang Hong‐Liang , Qi Yong‐Wen , Wang Tao
Published: November 2008

In this study, the genetic diversity of 51 cultivars in the primary core collection of peach (Prunus persica (L.) Batsch) was evaluated by using simple sequence repeats (SSRs). The phylogenetic relationships and the evolutionary history among different cultivars were determined on the basis of SSR data. Twenty‐two polymorphic SSR primer pairs were selected, and a total of 111 alleles were identified in the 51 cultivars, with an average of 5 alleles per locus. According to traditional Chinese classification of peach cultivars, the 51 cultivars in the peach primary core collection belong to six variety groups. The SSR analysis revealed that the levels of the genetic diversity within each variety group were ranked as Sweet peach > Crisp peach > Flat peach > Nectarine > Honey Peach > Yellow fleshed peach. The genetic diversity among the Chinese cultivars was higher than that among the introduced cultivars. Cluster analysis by the unweighted pair group method with arithmetic averaging (UPGMA) placed the 51 cultivars into five linkage clusters. Cultivar members from the same variety group were distributed in different UPGMA clusters and some members from different variety groups were placed under the same cluster. Different variety groups could not be differentiated in accordance with SSR markers. The SSR analysis revealed rich genetic diversity in the peach primary core collection, representative of genetic resources of peach.
Eco‐physiological Characteristics of Alfalfa Seedlings in Response to Various Mixed Salt‐alkaline Stresses
Authors: Peng Yong‐Lin , Gao Zhan‐Wu , Gao Ying , Liu Guo‐Fang , Sheng Lian‐Xi , Wang De‐Li
Published: November 2008

Soil salinization and alkalization frequently co‐occur in nature, but little is known about the mixed effects of salt‐alkaline stresses on plants. An experiment with mixed salts (NaCl, Na2SO4, NaHCO3 and Na2CO3) and 30 salt‐alkaline combinations (salinity 24–120 mmol/L and pH 7.03–10.32) treating Medicago sativa seedlings was conducted. The results demonstrated that salinity and alkalinity significantly affected total biomass and biomass components of seedlings. There were interactive effects of salt composition and concentration on biomass (P≤ 0.001). The interactions between salinity and alkalinity stresses led to changes in the root activity along the salinity gradient (P≤ 0.001). The effects of alkalinity on seedling survival rate were more significant than those of salinity, and the seedlings demonstrated some physiological responses (leaf electrolyte leakage rate and proline content) in order to adapt to mixed salt‐alkaline stresses. It was concluded that the mixed salt‐alkaline stresses, which differ from either salt or alkali stress, emphasize the significant interaction between salt concentration (salinity) and salt component (alkalinity). Further, the effects of the interaction between high alkalinity and salinity are more severe than those of either salt or alkali stress, and such a cooperative interaction results in more sensitive responses of ecological and physiological characteristics in plants.
Community conserved areas: policy issues in historic and contemporary context
Authors: Berkes Fikret
Published: November 2008

Indigenous and community conserved areas (ICCAs) are natural and/or modified ecosystems containing biodiversity values, ecological services, and cultural values, voluntarily conserved by indigenous and other communities through local or customary laws. They are found in both terrestrial and marine areas; they range in size from <1 ha sacred groves to >30,000 km2 indigenous territories in Brazil. ICCAs should be recognized for what they may contribute to national and global conservation systems, but there is little documentation of their potential or discussion of their policy implications. Here I examine the historic and contemporary context of ICCAs, provide examples, and raise policy issues related to: assessing the conservation benefits of ICCAs, integrating traditional knowledge into protected area management, finding the right mix of governance regimes, and dealing with challenges faced by them.
Wide Gap Braze Repair Using Vertically Laminated Repair Scheme
Authors: Nagy Doug , Huang Xiao
Published: November 2008

Repair of after-service gas turbine hot section superalloy components provides considerable saving in life-cycle cost of engines. Whereas a number of methods have been used in the past to repair these superalloy components, wide gap brazing technology has provided a practical alternative to repair difficult-to-weld alloys with substantial damages. In this paper, the historical development of wide gap repair technologies is reviewed first. Subsequently, the recent development in utilizing a vertically laminated structure to repair a large and deep gap (up to 16 mm) in one brazing cycle will be discussed. The microstructure resulted from this repair scheme will be evaluated and compared with conventional wide gap braze with slurry and that of the Liburdi powder metallurgy (LPM™) process. It is observed that in conventional wide gap brazing with premixed slurry, the presence of intermetallic compounds can be effectively reduced by reducing the ratio of braze alloy to gap filler, which, however, also contributes to the increased occurrence of macroscopic voids in the wide gap joint. The LPM™ method, on the other hand, can achieve a macroscopically void-free repair of gap (up to 6 mm) and minimize the formation of intermetallics. By using a vertically laminated repair scheme it is shown that the process is able to repair a deeper gap (up to 16 mm) with no macroscopic defects and reduced intermetallic compounds.
The Performance Evaluation With Diffuser Geometry Variations of the Centrifugal Compressor in a Marine Engine (70MW) Turbocharger
Authors: Kim Hong-Won , Park Jong-II , Ryu Seung-Hyup , Choi Seong-Wook , Ghal Sang-Hak
Published: November 2008

An examination of the condition of the flow leaving the impeller exit kinetic energy often accounts for 30–50% of the shaft work input to the compressor stage; for energy efficiency, it is important to recover as much of this as possible. This is the function of the diffuser, which follows the impeller. Effective pressure recovery downstream of an impeller is very important in order to realize a centrifugal compressor with a high efficiency and a high pressure ratio, and an appropriate selection of a diffuser for a specific impeller is a critical step in order to develop the compressor accordingly. The purpose of this study is to investigate the sensitivity of how compressor performances change as the vaned diffuser geometry is varied. Three kinds of vaned diffusers were studied and compared with its results. The first vaned diffuser type is based on a modified NACA airfoil, the second is a channel diffuser, and the third is a conformal transformation of NACA 65-(4A10)06 airfoil. A mean-line prediction method was applied to investigate the performance and stability for three kinds of diffusers. Computational fluid dynamic (CFD) analyses and a detailed interior flow pattern study have been done. In this study, the off-design behavior of three different types of diffusers, given by the mean-line prediction, was investigated using CFD results and the NACA 65 diffuser geometry, which satisfies a wider operating range and has a higher pressure recovery than the others, was selected. The numerical results were compared with experimental data for validation and showed good agreement.
Three-Dimensional Computational Fluid Simulation of Diesel and Dual Fuel Engine Combustion
Authors: Liu Chengke , Karim G. A.
Published: November 2008

A 3D computational fluid dynamics model with a reduced detailed chemical kinetics of the combustion of diesel and methane fuels is developed while considering turbulence during combustion to simulate the mixture flow, formation, and combustion processes within diesel and diesel/methane dual fuel engines having swirl chambers. The combustion characteristics of the pilot injection into a small prechamber are also investigated. Modeled results were validated by a group of corresponding experimental data. The spatial and temporal distributions of the mixture temperature, pressure, and velocity under conditions with and without liquid fuel injection and combustion are compared. The effects of engine speed, injection timing, and the addition of carbon dioxide on the combustion process of dual fuel engines are investigated. It is found that in the absence of any fuel injection and combustion, the swirl center is initially formed at the bottom-left of the swirl chamber, and then moved up with continued compression in the top-right direction toward the highest point. The swirling motion within the swirl and main combustion chambers promotes the evaporation of the liquid pilot and the combustion processes of diesel and dual fuel engines. It was observed that an earlier autoignition can be obtained through injecting the pilot fuel into the small prechamber compared with the corresponding swirl chamber operation. It is to be shown that reduced engine emissions and improved thermal efficiency can be achieved by a two-stage homogenous charge compression ignition combustion.
A Study on Flow and Heat Transfer in Strongly Curved U-Bend
Authors: Amano R. S. , Song B. , Reza M. S.
Published: November 2008

The secondary flows inside a sharp U-bend are numerically studied by using several different turbulence models. The finite volume difference method incorporated with the higher-order bounded interpolation scheme has been employed in the present study. The present results reveal that non-linear low-Re k-ω model and the other models produce the quite different secondary flow patterns. It is shown that the present non-linear model produces satisfactory predictions of the flow development inside the sharp U-bend comparing with linear Launder-Sharma model.
Detached Eddy Simulation of Film Cooling Performance on the Trailing Edge Cut-Back of Gas Turbine Airfoils
Authors: Martini P. , Schulz A. , Bauer H.-J. , Whitney C. F.
Published: November 2008

The present study deals with the unsteady flow simulation of trailing edge film cooling on the pressure side cut-back of gas turbine airfoils. Before being ejected tangentially on the inclined cut-back surface, the coolant air passes a partly converging passage that is equipped with turbulators such as pin fins and ribs. The film mixing process on the cut-back is complicated. In the near slot region, due to the turbulators and the blunt pressure side lip, turbulence is expected to be anisotropic. Furthermore, unsteady flow phenomena like vortex shedding from the pressure side lip might influence the mixing process (i.e. the film cooling effectiveness on the cut-back surface). In the current study, three different internal cooling designs are numerically investigated starting from the steady RaNS solution, and ending with unsteady detached eddy simulations (DES). Blowing ratios M = 0.5; 0.8; 1.1 are considered. To obtain both, film cooling effectiveness as well as heat transfer coefficients on the cut-back surface, the simulations are performed using adiabatic and diabatic wall boundary conditions. The DES simulations give a detailed insight into the unsteady film mixing process on the trailing edge cut-back, which is indeed influenced by vortex shedding from the pressure side lip. Furthermore, the time averaged DES results show very good agreement with the experimental data in terms of film cooling effectiveness and heat transfer coefficients.
Turbomachinery Modeling: Explicit and Impliit Knowledge Capturing (2005A)
Authors: Japikse David , Oliphant Kerry N.
Published: November 2008

Design engineers rely on quality performance models to establish the physical relationship between diverse thermodynamic, geometric, and fluid dynamic parameters that govern turbomachinery performance. If these models are based on a rigorous, scientific foundation, they permit the designer to thoroughly optimize a new configuration and establish with confidence the performance levels to be expected when the product is introduced in the market. The process of developing advanced models has endured more than a full century, and models of increased complexity have been introduced. However, many aspects of model development have not received thorough scientific evaluation. In the turbomachinery field, meanline performance models for axial turbines have been well developed and widely published; nearly the same can be said for the field of axial compressors. Beyond these two examples, there is a need for more model development and improvement, particularly emphasizing radial and mixed-flow turbomachines. This paper shows a systematic method, now fully integrated into a computerized methodology with optimization search techniques, for extracting the greatest useful knowledge from diverse datasets suitable for subsequent model development. The process focuses on modeling eight dependent variables based on five or six independent variables that have been found to be essential for understanding the performance of these machines. This paper emphasizes the scientific and numerical approach taken to process the data such that advanced models can be developed. The actual model development is presented in subsequent papers.
Unsteady 3D-Numerical Investigation of the Influence of the Blading Design on the Stator-Rotor Interaction in a 2-Stage Turbine
Authors: Bohn Dieter E. , Ren Jing , Tu¨mmers Christian , Sell Michael
Published: November 2008

An important goal in the development of turbine bladings is improving their efficiency to achieve an optimized usage of energy resources. This requires a detailed insight into the complex 3D-flow phenomena in multi-stage turbines. In order to investigate the flow characteristics of modern highly loaded turbine profiles, a test rig with a two-stage axial turbine has been set up at the Institute of Steam and Gas Turbines, Aachen University. The test rig is especially designed to investigate different blading designs. In order to analyze the influence of the blade design on the unsteady blade row interaction, the 3D flow through the two-stage turbine is simulated numerically, using an unsteady Navier-Stokes computer code. The investigations include a comparison of two bladings with different design criteria. The reference blading is a commonly used cylindrical designed blading. This blade design will be compared with a bow-blading, which is designed to minimize the secondary flow phenomena near the endwall in order to achieve a balanced mass flow through nearly the whole passage height. The investigations will focus on the different loss behavior of the two bladings. Unsteady profile pressure distributions and radial efficiencies of the two blade designs will be discussed in detail. The flow conditions are taken from experimental investigations performed at the Institute of Steam and Gas Turbines. On the basis of the experiments a validation of the code will be performed by comparing the numerical results to the corresponding experimental data at the inlet and the outlet of the blading.
Numerical and Theoretical Study of Flow and Heat Transfer in a Pre-Swirl Rotor-Stator System
Authors: Farzaneh-Gord Mahmood , Wilson Mike , Owen J. Michael
Published: November 2008

In a “direct-transfer” pre-swirl supply system, cooling air flows axially across the wheel space from stationary pre-swirl nozzles to receiver holes located at a similar radius in the rotating turbine disc. This paper describes a combined numerical and theoretical study of flow and heat transfer in such a system. As 3D computations involve long computing times and large resources, a simplified axisymmetric model has been used to study the effects of flow parameters on flow and heat transfer in a rotor-stator pre-swirl system. This allows the effects of the main non-dimensional parameters on the flow and heat transfer in the system to be studied with computing times reduced by a factor of around 7 compared with 3-dimensional computations. The computed results are compared with available measured data. An expression has been derived for calculating the adiabatic effectiveness of the system, and this has been been compared with computed values. The computations show that, due to mixing losses, there is a significant drop in angular momentum. The computed flow structure is compared with free vortex behaviour between the pre-swirl inlet and the receiver outlet. The computed moment coefficient decreases as pre-swirl ratio increases and increases as non-dimensional flow rate increases. The computed average Nusselt number decreases with inlet swirl ratio up to a critical value and then increases again.
Aerodynamic Performance of a Family of Three High Pressure Transonic Turbine Blades at Off-Design Incidence
Authors: Corriveau D. , Sjolander S. A.
Published: November 2008

Linear cascade measurements for the aerodynamic performance of three transonic High Pressure (HP) turbine blades have been presented previously by Corriveau and Sjolander [1] [2] for the design incidence. The airfoils were designed for the same inlet and outlet velocity triangles but varied in their loading distributions. Results from the earlier studies indicated that by shifting the loading towards the rear of the airfoil an improvement in the profile loss performance of the order of 20% could be obtained near the design Mach number of 1.05. The measurements have been extended to off-design incidence to investigate the effects of incidence on the performance of HP turbine blades having differing loading distributions. The additional measurements were performed for incidence values of −10.0°, +5.0°, and +10.0° relative to the design incidence. In addition, two-dimensional Navier-Stokes numerical simulations of the cascade flow were performed in order to help in the interpretation of the experimental results. The exit Mach number was kept at the design value of 1.05. The corresponding Reynolds numbers, based on outlet velocity and true chord, is roughly 10 × 105. The measurements include midspan losses, outlet flow angles, blade loading distributions and base pressures. The results show that the superior loss performance of the aft-loaded profile, observed at design incidence and Mach number, could also be seen for off-design values of incidence ranging from about −5.0° to +5.0°. However, it was found that for incidences greater than about +5.0° the performance of the aft-loaded blade deteriorated rapidly. The front-loaded airfoil showed generally similar performance to that of the baseline mid-loaded airfoil up to an incidence of +5.0°, at which point its performance also deteriorates significantly.
The Effect of Roughness Element Fillet Radii on the Heat Transfer Enhancement in an Impingement Cooling System
Authors: Son Changmin , Ireland Peter , Gillespie David
Published: November 2008

The combination of roughness elements with an impingement cooling systems offers an attractive means of achieving high heat transfer. Considerable care must be taken to choose the shape, size and the position of the roughness elements to maximise heat transfer and minimise pressure loss. In the last decade, many studies have been investigated the effect of changes in many of the geometric features, but little attention has been paid to the effect of the inevitable fillet. Blades and vanes are normally manufactured by casting so the fillet radius is unavoidable. The present paper investigates the effect of roughness element fillet radii on heat transfer enhancement in an impingement cooling system. Three configurations with streamwise ribs were studied. The streamwise ribs are all trapezoidal in cross section. In the three configurations the fillet radii are (1) 0mm (sharp-edged), (2) 3mm, and (3) 5mm. The extra heat transfer area of the sharp-edged, 3mm fillet and the 5mm fillet rib configurations are reported. Two-staggered arrays (a uniform & non-uniform hole diameter array) of impingement plates are used. The jets from odd numbered rows impinge between the ribs while the jets from even numbered rows impinge onto the ribs. Tests were conducted at three different mass flow rates for each configuration. The average and local jet Reynolds numbers varied between 21500 and 31500, and 17000 and 41000 respectively. The transient liquid crystal technique was used to produce detailed Nusselt number distributions and row resolved average Nusselt number levels. The heat transfer enhancement and pressure loss due to the streamwise ribs are also compared to the smooth surface impingement cooling channel. The research showed that the streamwise ribs with fillet radii produced lower Nusselt number levels than both sharp-edged ribs and impingement onto a smooth surface.
Axial Fan Optimization Using 3D Codes
Authors: Kuzmenko M. L. , Egorov I. N. , Shmotin Yu. N.
Published: November 2008

The paper presents examples of research aimed at axial fan optimization: both mechanical and aerodynamic. The optimization is based on up-to-date analysis and optimization tools. As the analysis tools the well-known commercial software packages (FINE/Design3D, CFX-TASCflow and ANSYS) are used, as well as the models developed by NPO Saturn. As the optimization tools the IOSO technology was used. This technology is based on the widespread application of the response surface technique. Two examples of real-world problems and their optimized solutions are presented in the paper. The first one is connected with the search for optimum geometry for the rotor of up-to-date fan. The goal of the research was to ensure highest strength indices of the rotor. The multi-objective approach was used to solve this task (5 objectives). As the analysis the ANSYS software code was used, while the search for optimum solutions was carried out using IOSO NM algorithm designed for parallel multi-objective optimization within the frameworks of IOSO Technology. As a result, the improvement of all strength indices was obtained (from 9 to 56% as compared with the prototype). The goal of the second optimization problem was to increase the efficiency of fan rotor in the given point of its characteristics considering the splitting of the flow into core and bypass ducts. The peculiarity of this problem was the necessity to keep strength constraints (multidisciplinary approach). To solve this problem the 3-D CFD code and multilevel algorithm of IOSO technology was used. The search for optimum was carried out in the multi-objective statement (the compromise between the efficiency levels for core and bypass contours was searched). The optimization research allowed the rise of the fan rotor efficiency by more than 1.5%.
Numerical Study of the Effects of Bowed Blades on Aerodynamic Characteristics in a High Pressure Turbine
Authors: Hassan Vand Mohsen , Wang Songtao
Published: November 2008

A commercial N-S solver has been employed for simulating the unsteady flow field and analyzing aerodynamic characteristics in a steam turbine stage with low aspect ratio in two cases, one with straight and the other with bowed stator blades. The stator and rotor trailing edge wakes have been studied and compared for two cases. In blade-to-blade view, it was observed that the strength, position and the width or range of influence of wakes in bowed stator blades are bigger than those of straight blades. This effect causes remarkable changes in rotor flow and rotor trailing edge wakes. By analyzing the wake-induced turbulence, it was found that there is a periodic distribution for stator trailing wakes along the radial direction in straight blades, while for bowed blades; the distribution is concentrated towards the midspan. The bowing of stator blades causes the rotor trailing wakes to be greatly strengthened near the hub and casing. The blade loading distribution, viscous dissipation and rotor tip leakage flow for straight and bowed blades are compared in detail to show the aerodynamic performance of stator blade bowing.
Heat Transfer and Film-Cooling Measurements on a Stator Vane With Fan-Shaped Cooling Holes
Authors: Colban W. , Gratton A. , Thole K. A. , Haendler M.
Published: November 2008

In a typical gas turbine engine, the gas exiting the combustor is significantly hotter than the melting temperature of the turbine components. The highest temperatures in an engine are typically seen by the turbine inlet guide vanes. One method used to cool the inlet guide vanes is film-cooling, which involves bleeding comparatively low-temperature, high-pressure air from the compressor and injecting it through an array of discrete holes on the vane surface. To predict the vane surface temperatures in the engine, it is necessary to measure the heat transfer coefficient and adiabatic film-cooling effectiveness on the vane surface. This study presents heat transfer coefficients and adiabatic effectiveness levels measured in a scaled-up, two-passage cascade with a contoured endwall. Heat transfer measurements indicated that the behavior of the boundary layer transition along the suction side of the vane showed sensitivity to the location of film-cooling injection, which was simulated through the use of a trip wire placed on the vane surface. Single row adiabatic effectiveness measurements without any upstream blowing showed jet lift-off was prevalent along the suction side of the airfoil. Single row adiabatic effectiveness measurements on the pressure side, also without upstream showerhead blowing, indicated jet lifted-off and then reattached to the surface in the concave region of the vane. In the presence of upstream showerhead blowing, the jet lift-off for the first pressure side row was reduced, increasing adiabatic effectiveness levels.