bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐Term Variability of Inflammatory Markers and Associated Factors in a Population‐Based Cohort
Authors: Nash Scott D. , Cruickshanks Karen J. , Klein Ronald , Klein Barbara E.K. , Javier Nieto F. , Chappell Rick , Schubert Carla R. , Tsai Michael Y.
Published: July 2013

Objectives

To investigate long‐term variability in serum high‐sensitivity C‐reactive protein (CRP) and interleukin‐6 (IL‐6) and to determine associated risk factors for high‐risk inflammatory profiles.

Design

Prospective population‐based cohort study.

Participants

Participants (N = 1,443) of the Epidemiology of Hearing Loss Study and the Beaver Dam Eye Study, two population‐based prospective studies of aging in the same cohort.

Measurements

In participants aged 43 to 79 at the initial examination (1988–1990), serum high‐sensitivity CRP was measured from three time‐points (1988–1990, 1998–2000, 2009–2010), and serum IL‐6 was measured from two (1998–2000, 2009–2010).

Results

When IL‐6 levels were categorized into tertiles, 50.8% of participants were in the same group 10 years later (weighted kappa (κ) = 0.34). When CRP was categorized into three risk groups, 53.4% of participants were in the same group 10 years later (κ = 0.36), and 32.4% were in the same group at all three examinations (κ = 0.27). IL‐6 increased from a geometric mean of 1.54 pg/L to 1.78 pg/L over 10 years, whereas CRP increased from a geometric mean of 1.67 mg/L to 2.25 mg/L over 10 years and then decreased to 1.93 mg/L over the next 10 years. These 10‐year decreases in CRP were not observed in those not reporting statin use. Factors associated with long‐term higher levels of IL‐6 and CRP were older age (IL‐6), obesity, smoking, lower physical activity (IL‐6), lower high‐density lipoprotein cholesterol (IL‐6), and a history of statin (non)use (CRP).

Conclusion

Inflammatory marker levels tracked over the long term into older age with within‐person increases were observed. Several potentially modifiable risk factors were associated with long‐term higher levels of inflammatory markers.
Association of dietary habits with levels of physical activity and screen time among adolescents living inSaudiArabia
Authors: Al‐Hazzaa H. M. , Al‐Sobayel H. I. , Abahussain N. A. , Qahwaji D. M. , Alahmadi M. A. , Musaiger A. O.
Published: July 2013

Background

Understanding the inter‐relationships between lifestyle factors in youth is important with respect to the development of effective promotional programmes for healthy eating and active living. The present study aimed to explore the associations of dietary habits (DH) with physical activity (PA) and screen time (ST) among Saudi adolescents aged between 15 and 19 years of age relative to gender.

Methods

Data were obtained from theArabTeensLifestyleStudy, a school‐based multicentre lifestyle study conducted in 2009/2010 in three major cities inSaudiArabia. A multistage stratified cluster random sampling technique was used. The number of participants with complete data forDHandPAwas 2886 and the respective number forDHandSTwas 2822. Assessment included weight, height,body mass index, total dailyST(televisionviewing, video/computer games and Internet use),PAandDHusing self‐reported questionnaires.

Results

Females were significantly more sedentary and less active than males (P < 0.001). Two‐way analysis of covariance, controlling for age, showed significant (P < 0.05) gender byPAand gender bySTinteractions for severalDH. Logistic regression analyses revealed significant associations of higherPAwith a higher consumption of fruit, vegetables, milk,French fries/potato chips and energy drinks, whereas higherSTwas significantly associated with a higher consumption of sugar‐sweetened drinks, fast foods, cake/doughnuts and energy drinks.

Conclusions

Healthful dietary habits were associated mostly withPA, whereas sedentary behaviours, independent ofPA, negatively impacted upon eating behaviours. The lowPAlevels and high sedentary levels ofSaudi females represent a great concern. The results reported in the present study have important implications for both youth public health policies and intervention programmes.
Narratives of breathlessness in chronic obstructive pulmonary disease
Authors: Kvangarsnes Marit , Torheim Henny , Hole Torstein , Öhlund Lennart S
Published: July 2013

Aims and objectives

To explore patient perceptions of chronic obstructive pulmonary disease exacerbation and the patients' experiences of their relations with health personnel during care and treatment.

Background

Patients suffering from acute exacerbation of chronic obstructive pulmonary disease often experience life‐threatening situations and undergo noninvasive positive‐pressure ventilation via bi‐level positive airway pressure in a hospital setting. Theory on trust, which often overlaps with the issue of power, can shed light on patient's experiences during an acute exacerbation.

Design

Narrative research design was chosen.

Methods

Ten in‐depth qualitative interviews (n = 10) were conducted with patients who had been admitted to two intensive care units in Western Norway during the autumn of 2009 and the spring of 2010. Narrative analysis and theories on trust and power were used to analyse the interviews.

Results

Because of their breathlessness, the patients perceived that they were completely dependent on others during the acute phase. Some stated that they had experienced an altered perception of reality and had not understood how serious their situation was. Although the patients trusted the health personnel in helping them breathe, they also told stories about care deficiencies and situations in which they felt neglected.

Conclusions

This study shows that patients with an acute exacerbation of chronic obstructive pulmonary disease often feel wholly dependent on health personnel during the exacerbation and, as a result, experience extreme vulnerability.

Relevance to clinical practice

The findings give nurses insight into building trust and a good relationship between patient and caregiver during an acute exacerbation of chronic obstructive lung disease.
Dynamic Trading with Predictable Returns and Transaction Costs
Authors: GÂRLEANU NICOLAE , PEDERSEN LASSE HEJE
Published: July 2013

We derive a closed‐form optimal dynamic portfolio policy when trading is costly and security returns are predictable by signals with different mean‐reversion speeds. The optimal strategy is characterized by two principles: (1) aim in front of the target, and (2) trade partially toward the current aim. Specifically, the optimal updated portfolio is a linear combination of the existing portfolio and an “aim portfolio,” which is a weighted average of the current Markowitz portfolio (the moving target) and the expected Markowitz portfolios on all future dates (where the target is moving). Intuitively, predictors with slower mean‐reversion (alpha decay) get more weight in the aim portfolio. We implement the optimal strategy for commodity futures and find superior net returns relative to more naive benchmarks.
Country Size, Currency Unions, and International Asset Returns
Authors: HASSAN TAREK A.
Published: July 2013

Differences in real interest rates across developed economies are puzzlingly large and persistent. I propose a simple explanation: bonds issued in the currencies of larger economies are expensive because they insure against shocks that affect a larger fraction of the world economy. I show that, indeed, differences in the size of economies explain a large fraction of the cross‐sectional variation in currency returns. The data also support additional implications of the model: the introduction of a currency union lowers interest rates in participating countries, and stocks in the nontraded sector of larger economies pay lower expected returns.
Borrow Cheap, Buy High? The Determinants of Leverage and Pricing in Buyouts
Authors: AXELSON ULF , JENKINSON TIM , STRÖMBERG PER , WEISBACH MICHAEL S.
Published: July 2013

Private equity funds pay particular attention to capital structure when executing leveraged buyouts, creating an interesting setting for examining capital structure theories. Using a large, international sample of buyouts from 1980 to 2008, we find that buyout leverage is unrelated to the cross‐sectional factors, suggested by traditional capital structure theories, that drive public firm leverage. Instead, variation in economy‐wide credit conditions is the main determinant of leverage in buyouts. Higher deal leverage is associated with higher transaction prices and lower buyout fund returns, suggesting that acquirers overpay when access to credit is easier.
Effect of Melamine Foam Cleaning on the Surface Condition of Composite Resin Artificial Teeth
Authors: Tanaka Rika , Kurogi Tadafumi , Murata Hiroshi
Published: July 2013

Purpose

The purpose of this study was to examine the abrasive and cleaning effects of melamine foam and other cleaning agents on the surfaces of composite resin artificial tooth specimens.

Materials and Methods

A stained composite resin artificial tooth in a used denture was cleaned using a denture brush and melamine foam, and the stain removal effect was evaluated macroscopically. Next, 5 types of cleaning material (fourfold‐compression melamine foam, MEL; brush with water, BRU; denture dentifrice without abrasive, POL; denture dentifrice with abrasive, TAF; conventional dentifrice, AQU) and 15 plate‐shaped specimens made of composite resin for artificial teeth were used for wear tests. The surface roughness was measured using a laser scanning microscope. Furthermore, the surface properties were observed using a digital microscope. Surface roughness data were analyzed by two‐way ANOVA followed by Tukey's test.

Results

Artificial tooth stains that could not be removed by brushing became removable using melamine foam. With regard to surface roughness in the context of the wear test, significant differences were not indicated between MEL and POL, whereas BRU‐, TAF‐, and AQU‐treated specimens showed significantly increased surface roughness (p < 0.05). In the comparison among the cleaning materials, TAF‐ and AQU‐treated specimens showed significantly rougher surfaces than those treated with MEL, BRU, and POL (p < 0.05).

Conclusions

Macroscopic observations suggest that melamine foam would be effective for the removal of stains on composite resin artificial teeth. Traces of wear were not observed in specimens treated with melamine foam and the denture dentifrice not containing abrasives. It was suggested that these two materials would be desirable and useful to use for composite resin tooth cleaning.
Accuracy of Ringless Casting and Accelerated Wax‐Elimination Technique: A Comparative In Vitro Study
Authors: Prasad Rahul , Al‐Keraif Abdulaziz Abdullah , Kathuria Nidhi , Gandhi P.V. , Bhide S.V.
Published: July 2013

Purpose

The purpose of this study was to determine whether the ringless casting and accelerated wax‐elimination techniques can be combined to offer a cost‐effective, clinically acceptable, and time‐saving alternative for fabricating single unit castings in fixed prosthodontics.

Materials and Methods

Sixty standardized wax copings were fabricated on a type IV stone replica of a stainless steel die. The wax patterns were divided into four groups. The first group was cast using the ringless investment technique and conventional wax‐elimination method; the second group was cast using the ringless investment technique and accelerated wax‐elimination method; the third group was cast using the conventional metal ring investment technique and conventional wax‐elimination method; the fourth group was cast using the metal ring investment technique and accelerated wax‐elimination method. The vertical marginal gap was measured at four sites per specimen, using a digital optical microscope at 100× magnification. The results were analyzed using two‐way ANOVA to determine statistical significance.

Results

The vertical marginal gaps of castings fabricated using the ringless technique (76.98 ± 7.59 μm) were significantly less (p < 0.05) than those castings fabricated using the conventional metal ring technique (138.44 ± 28.59 μm); however, the vertical marginal gaps of the conventional (102.63 ± 36.12 μm) and accelerated wax‐elimination (112.79 ± 38.34 μm) castings were not statistically significant (p > 0.05).

Conclusions

The ringless investment technique can produce castings with higher accuracy and can be favorably combined with the accelerated wax‐elimination method as a vital alternative to the time‐consuming conventional technique of casting restorations in fixed prosthodontics.
Practice‐Based Evidence from 29‐Year Outcome Analysis of Management of the Edentulous Jaw Using Osseointegrated Dental Implants
Authors: Dhima Matilda , Paulusova Vladimira , Lohse Christine , Salinas Thomas J. , Carr Alan B.
Published: July 2013

Purpose

The aim of this retrospective study was to summarize practice‐based evidence associated with long‐term outcomes (>20 years) in the management of edentulous patients. The patient population was managed with implant‐supported prostheses, following the original osseointegration protocol, provided over the period from 1983 to 1991 in the group prosthodontics practice at the Mayo Clinic. The data are an example of practice quality assurance monitoring and are used to refine care delivery when needed and to provide information regarding expected outcomes in a shared decision‐making interaction with prospective patients.

Materials and Methods

Two hundred and sixty four patients with at least one edentulous jaw were identified. Of these, 255 completed their care and follow‐up at the Mayo Clinic (209 mandible only, 35 maxilla only, 11 mandible and maxilla). Prosthodontic outcomes categorized as anticipated or unanticipated prosthetic and biologic events and the respective interventions required for each were recorded to assess follow‐up event dynamics for this care modality.

Results

The mean duration of follow‐up for 190 of the 255 patients (65 died at a mean follow‐up of 12.6 years) was 13.0 years (median 13.6; range 0.3 to 28). At least one prosthetic event was experienced by 148 patients (58%), and 81 (32%) experienced at least one biologic event. Overall, patients experienced 3.8 times more prosthetic events than biologic events. Twenty‐four (9%) patients experienced 35 implant failures. Overall survival rates at 20 years were 86% for prostheses, 15% survived free of any event, and 92% experienced survival free of implant failure (95% confidence interval).

Conclusion

Anticipated and unanticipated prosthetic events occur throughout the life of the hybrid prosthesis. Prosthetic events significantly surpass (four times more) biologic events and occur significantly later in the follow‐up. For this patient group, 8.6% (22/255) had implant‐supported prostheses remade during follow‐up in this patient population. These findings support the recommendation that prosthodontic care for missing teeth be thought of in a “chronic condition” context, recognizing that long‐term outcome monitoring to provide realistic care expectations is important for demonstrating care value in oral health promotion.
Prairie Rattlesnake Envenomation in 27 New World Camelids
Authors: Sonis J.M. , Hackett E.S. , Callan R.J. , Holt T.N. , Hackett T.B.
Published: July 2013

Background

Morbidity and case fatality from rattlesnake envenomation is regionally specific because of variability in relative toxicity of the species of snake encountered. A previous report of rattlesnake envenomation inNewWorld camelids (NWC) from the western coastalUnitedStates documented high case fatality rates and guarded prognosis for survival.

Hypothesis/Objectives

To describe clinical findings, treatments, and outcome ofNWCwith prairie rattlesnake (Crotalus viridis viridis) envenomation in theRockyMountain region of theUnitedStates.

Animals

Twenty‐sevenNWCadmitted to theColoradoStateUniversityVeterinaryTeachingHospital for evaluation of acute rattlesnake envenomation between 1992 and 2012.

Methods

Medical records ofNWCevaluated for rattlesnake envenomation as coded by the attending clinician and identified by a database search were reviewed retrospectively. Month of admission, signalment, area of bite, clinical and clinicopathologic data, treatments, and outcome were recorded.

Results

Twenty‐five llamas and 2 alpacas were admitted for envenomation. Llamas were overrepresented compared to hospital caseload. The face was the most common site of envenomation, observed in 96% of recorded cases. Presenting clinical signs included fever, tachypnea, tachycardia, and respiratory distress. Nine animals required a tracheotomy. Median hospitalization time was 3 days and overall survival rate was 69%.

Conclusions and Clinical Importance

Case fatality rate for prairie rattlesnake envenomation inNWCwas lower than that reported in theWestern coastal region of theUnitedStates and similar to that reported for prairie rattlesnake envenomation in horses.
Phase I Dose Escalation of Doxorubicin Chemotherapy in Tumor‐Bearing Equidae
Authors: Théon A.P. , Pusterla N. , Magdesian K.G. , Wilson W.D.
Published: July 2013

Background

There is no information on the use of doxorubicin in horses with tumors.

Objective

To determine dose‐limiting toxicosis (DLT) and maximum tolerated dose (MTD) of doxorubicin in tumor‐bearing horses.

Animals

Seventeen horses with 34 localized or multicentric advanced tumors.

Methods

Two‐stage dose‐ranging design involving intrapatient and interpatient dose escalation. Treatment protocol included 6 treatment cycles given at 3‐week intervals with dosages ranging from 40 to 85 mg/m2. Clinical signs, hematologic, and nonhematologic changes were evaluated.

Results

Total doses ranged from 1,127 to 2,900 mg in 12 horses that completed the assigned treatment protocols. TheMTDwas 75 mg/m2. Hypersensitivity reactions and neutropenia were dose limiting. Hypersensitivity was dose‐dependent but schedule invariant. Neutropenia was dose‐ and cycle‐dependent but dose‐escalation schedule invariant. Cardiotoxicity was not observed.

Conclusion and Clinical Relevance

The recommended dosage of doxorubicin to treat horses is 70 mg/m2given at 3‐week intervals as single agent. Adjunctive treatment with antihistamines and nonsteroidal anti‐inflammatory drugs is recommended to control hypersensitivity.
Prospectively Recorded versus Medical Record‐Derived Spinal Cord Injury Scores in Dogs with Intervertebral Disk Herniation
Authors: Van Wie E.Y. , Fosgate G.T. , Mankin J.M. , Jeffery N.D. , Kerwin S.C. , Levine G.J. , Greatting H.H. , Chen A.V. , Barker A.K. , Levine J.M.
Published: July 2013

Background

Validated spinal cord injury (SCI) scores have been established for veterinary species but are not uniformly used in practice.

Hypothesis/objectives

To determine the level of agreement of SCI scores at the time of admission versus those assigned from reconstructed medical records in a population of dogs with intervertebral disk herniation (IVDH).

Animals

Eighty‐six client‐owned dogs with confirmed IVDH.

Methods

Retrospective study. Medical records were reviewed for history, physical examination, neurologic examination, and recorded Modified Frankel score (MFS) and Texas spinal cord injury score (TSCIS) at the time of admission. Three raters, all board‐certified neurologists, assigned MFS and TSCIS based on digitized abstracted medical records to each patient. These scores were then compared to the recorded score at the time of admission.

Results

Actual agreement for MFS and TSCIS derived from medical records by the 3 raters compared to prospectively derived MFS and TSCIS was 77.9 and 51.2%, respectively. A kappa value of 0.572 (95% CI 0.450, 0.694; P < .001) and an ICC of 0.533 (95% CI 0.410, 0.646; P < .001) were calculated for MFS scores. A kappa value of 0.100 (95% CI 0.000, 0.222; P = .107), and an ICC of 0.503 (95% CI 0.377, 0.620; P < .001) were calculated for TSCIS scores.

Conclusions and Clinical Importance

Results showed that SCI scores recorded at the time of admission often do not agree with those retrospectively abstracted from medical records. Agreement was less when using the more complex TSCIS scale and therefore the MFS scale might be more appropriate for use in retrospective studies.
Applicability of 3T BodyMRIin Assessment of Nonfocal Bone Marrow Involvement of Hematopoietic Neoplasia in Dogs
Authors: Feeney D.A. , Sharkey L.C. , Steward S.M. , Bahr K.L. , Henson M.S. , Ito D. , O'Brien T.D. , Jessen C.R. , Husbands B.D. , Borgatti A. , Modiano J.
Published: July 2013

Background

The utility of whole body magnetic resonance imaging (MRI) in detecting bone marrow infiltration in dogs with cancer has not been investigated.

Objectives

To assess the feasibility of 3T bodyMRIfor bone marrow assessment in dogs with hematopoietic neoplasia.

Animals

Seven dogs with B‐cell lymphoma, 3 dogs with myelodysplastic syndrome (MDS), and 2 clinically normal dogs.

Methods

A prospective study of dogs with hematopoetic cancer was conducted using T1W, T2W, In‐Phase, Out‐of‐Phase and STIR pulse sequences of the body excluding the head prior to bone marrow sampling. The relative signal intensity of a midlumbar vertebral body and a midshaft femoral bone marrow was compared by visual and point region of interest analysis to regional skeletal muscle.

Results

Similarity of femoral diaphyseal and vertebral body marrow signal intensity to that of skeletal muscle on the Out‐of‐Phase sequence was useful in distinguishing the 3 dogs with hypercellular marrow because ofMDSfrom the 7 dogs with B‐cell lymphoma and from the 2 clinically normal dogs. 1/7 dogs with lymphoma had proven bone marrow involvement but normal cellularity and less than 5% abnormal cells. Unaffected midfemoral marrow had greater signal intensity than skeletal muscle and unaffected vertebral marrow had less signal intensity than skeletal muscle on the Out‐of‐Phase sequence.

Conclusions and Clinical Importance

3T, Out‐of‐PhaseMRpulse sequence was useful in distinguishing diffuse bone marrow infiltrate (MDS) from minimally or unaffected marrow using skeletal muscle for signal intensity comparison on whole bodyMRI.
Preferences, Welfare and Desirable Subsidies under Monopolistic Competition
Authors: Kwan Chang Yee
Published: July 2013

A simple model of monopolistic competition with consumer preferences for diversity reconciles an empirical‐theoretical disconnect of the welfare properties of industrial subsidies. The optimal policy rules indicate that subsidies can bePareto improving, but subject to society's preference for diversity. More counter‐intuitively, the welfare‐maximizing subsidy is always found to be strictly non‐negative, and the general qualitative nature of the results seem to contradict the optimum taxation literature. The subsidy incidence is also examined and we find that there exists a potential for an over‐shifting of the subsidy.
Reconstructing the δ18O of atmospheric water vapour via the CAM epiphyte Tillandsia usneoides: seasonal controls on δ18O in the field and large‐scale reconstruction of δ18Oa
Authors: HELLIKER BRENT R.
Published: July 2013

Using both oxygen isotope ratios of leaf water (δ18OL) and cellulose (δ18OC) of Tillandsia usneoides in situ, this paper examined how short‐ and long‐term responses to environmental variation and model parameterization affected the reconstruction of the atmospheric water vapour (δ18Oa). During sample‐intensive field campaigns, predictions of δ18OL matched observations well using a non‐steady‐state model, but the model required data‐rich parameterization. Predictions from the more easily parameterized maximum enrichment model (δ18OL–M) matched observed δ18OL and observed δ18Oa when leaf water turnover was less than 3.5 d. Using the δ18OL–M model and weekly samples of δ18OL across two growing seasons in Florida, USA, reconstructed δ18Oa was −12.6 ± 0.3‰. This is compared with δ18Oa of −12.4 ± 0.2‰ resolved from the growing‐season‐weighted δ18OC. Both of these values were similar to δ18Oa in equilibrium with precipitation, −12.9‰. δ18Oa was also reconstructed through a large‐scale transect with δ18OL and the growing‐season‐integrated δ18OC across the southeastern United States. There was considerable large‐scale variation, but there was regional, weather‐induced coherence in δ18Oa when using δ18OL. The reconstruction of δ18Oa with δ18OC generally supported the assumption of δ18Oa being in equilibrium with precipitation δ18O (δ18Oppt), but the pool of δ18Oppt with which δ18Oa was in equilibrium – growing season versus annual δ18Oppt – changed with latitude.
Functional properties and expression quantitative trait loci for phosphate transporter GmPT1 in soybean
Authors: SONG HAINA , YIN ZHITONG , CHAO MAONI , NING LIHUA , ZHANG DAN , YU DEYUE
Published: July 2013

In this paper, we analyzed the function and modulation of the soybean phosphate transporter gene GmPT1. Overexpression of GmPT1 in tobacco showed that this gene played a role in Pi remobilization. In a soybean RIL population, the expression level of GmPT1 showed significantly positive correlations with seed yield, phosphorus‐use efficiency, photosynthetic rate (PN) and the quantum yield of PSII primary photochemistry (ΦPSII). Expression quantitative trait loci (eQTL) mapping for GmPT1 revealed one cis‐eQTL and one trans‐eQTL. These results suggest the possibility to improve soybean seed yields under Pi‐limiting conditions by modulating GmPT1 expression.
Beastly minds: a topological twist in the rethinking of the human in nonhuman geographies using two of Freud's case studies, Emmy von N. and the Wolfman
Authors: Pile Steve
Published: July 2013

This paper takes its cue from recent work in nonhuman geographies that has sought to think about the relationship between the human and nonhumantopologically. While nonhuman geographies have well‐developed analyses of the topologies of regions and networks, recent work is supplementing these with other topological understandings. Yet, this work can be taken further. To this end, this paper explores the relationship between the human and nonhuman, through a discussion of animals, affects and psychic space. It offers a topological reading of two of Freud's case studies: Emmy von N. and the Wolfman. The paper highlights the twists and turns of affect and psychic space in these cases. It shows that the difference between the human and the nonhuman can be radically uncertain at the very same time that human distinctiveness is being given certain forms. Using the topological figure of the Möbius strip, this paper shows that, while animals and humans might appear on the same topological surface, distinctions between them are not collapsed or fused or flattened. This has implications for how humans are understood to be entangled in nonhuman worlds; entanglements that, it is argued, are always filtered through the beastly mind.
Effects of low‐dose cyclophosphamide with piroxicam on tumour neovascularization in a canine oral malignant melanoma‐xenografted mouse model
Authors: Choisunirachon N. , Jaroensong T. , Yoshida K. , Saeki K. , Mochizuki M. , Nishimura R. , Sasaki N. , Nakagawa T.
Published: July 2013

Low‐dose cyclophosphamide (CyLD) has shown promise in the treatment of several cancers; however, the effect of CyLD on canine oral malignant melanoma has never been explored. In this study, we investigated the effects of CyLD with or without piroxicam (Px) on tumour neovascularization and vascular normalization in a canine oral malignant melanoma‐xenografted mice model. After treatment with CyLD, Px or a combination of both (CyPx), the growth of the tumour in the treatment groups was significantly suppressed compared to the control group at 30 days of treatment. Proliferation index was also significantly reduced by all treatments, only CyPx significantly lowered microvessel density and vascular endothelial growth factor (VEGF) levels. Additionally, CyLD significantly reduced the proportion of normal vessels and caused an imbalance between VEGF and thrombospondin‐1. These results suggested that CyPx has potent anti‐angiogenic effects in terms of both the number and quality of blood vessels in xenografted canine oral malignant melanoma.
Two- and Three-Dimensional Prescribed Surface Curvature Distribution Blade Design (CIRCLE) Method for the Design of High Efficiency Turbines, Compressors, and Isolated Airfoils
Authors: Korakianitis T. , Rezaienia M. A. , Hamakhan I. A. , Wheeler A. P. S.
Published: July 2013

The prescribed surface curvature distribution blade design (CIRCLE) method is presented for the design of two-dimensional (2D) and three-dimensional (3D) blades for axial compressors and turbines, and isolated blades or airfoils. The original axial turbine blade design method is improved, allowing it to use any leading-edge (LE) and trailing-edge (TE) shapes, such as circles and ellipses. The method to connect these LE and TE shapes to the remaining blade surfaces with curvature and slope of curvature continuity everywhere along the streamwise blade length, while concurrently overcoming the “wiggle” problems of higher-order polynomials is presented. This allows smooth surface pressure distributions, and easy integration of the CIRCLE method in heuristic blade-optimization methods. The method is further extended to 2D and 3D compressor blades and isolated airfoil geometries providing smooth variation of key blade parameters such as inlet and outlet flow angles, stagger angle, throat diameter, LE and TE radii, etc. from hub to tip. One sample 3D turbine blade geometry is presented. The efficacy of the method is examined by redesigning select blade geometries and numerically evaluating pressure-loss reduction at design and off-design conditions from the original blades: two typical 2D turbine blades; two typical 2D compressor blades; and one typical 2D isolated airfoil blade geometries are redesigned and evaluated with this method. Further extension of the method for centrifugal or mixed-flow impeller geometries is a coordinate transformation. It is concluded that the CIRCLE method is a robust tool for the design of high-efficiency turbomachinery blades.
Recent Advances in Manufacturing of Riblets on Compressor Blades and Their Aerodynamic Impact
Authors: Lietmeyer Christoph , Denkena Berend , Krawczyk Thomas , Kling Rainer , Overmeyer Ludger , Wojakowski Bodo , Reithmeier Eduard , Scheuer Renke , Vynnyk Taras , Seume Joerg R.
Published: July 2013

Since Oehlert et al. (2007, “Exploratory Experiments on Machined Riblets for 2-D Compressor Blades,” Proceedings of International Mechanical Engineering Conference and Exposition 2007, Seattle, WA, IMECE2007-43457), significant improvements in the manufacturing processes of riblets by laser structuring and grinding have been achieved. In the present study, strategies for manufacturing small-scale grooves with a spacing smaller than 40 μm by metal bonded grinding wheels are presented. For the laser-structuring process, significant improvements of the production time by applying diffractive optical elements were achieved. Finally, strategies for evaluating the geometrical quality of the small-scale surface structures are shown and results obtained with two different measuring techniques (SEM and confocal microscope) are compared with each other. The aerodynamic impact of the different manufacturing processes is investigated based upon skin friction reduction data obtained on flat plates as well as the profile-loss reduction of riblet-structured compressor blades measured in a linear cascade wind tunnel. Numerical simulations with MISES embedded in a Monte Carlo simulation (MCS) were performed in order to calculate the profile-loss reduction of a blade structured by grinding to define further improvements of the riblet-geometry. A numerical as well as experimental study quantifying the relevant geometrical parameters indicate how further improvements from the present 4% reduction in skin friction can be achieved by an additional decrease of the riblet tip diameter and a more trapezoidal shape of the groove in order to realize the 8% potential reduction.
Experimental-Based Redesigns for Trailing Edge Film Cooling of Gas Turbine Blades
Authors: Benson Michael , D. Yapa Sayuri , Elkins Chris , Eaton John K.
Published: July 2013

Magnetic resonance imaging experiments have provided the three-dimensional mean concentration and three component mean velocity field for a typical trailing edge film-cooling cutback geometry built into a conventional uncambered airfoil. This geometry is typical of modern aircraft engines and includes three dimensional slot jets separated by tapered lands. Previous analysis of these data identified the critical mean flow structures that contribute to rapid mixing and low effectiveness in the fully turbulent flow. Three new trailing edge geometries were designed to modify the large scale mean flow structures responsible for surface effectiveness degradation. One modification called the Dolphin Nose attempted to weaken strong vortex flows by reducing three dimensionality near the slot breakout. This design changed the flow structure but resulted in minimal improvement in the surface effectiveness. Two other designs called the Shield and Rounded Shield changed the land planform and added an overhanging land edge while maintaining the same breakout surface. These designs substantially modified the vortex structure and improved the surface effectiveness by as much as 30%. Improvements included superior coolant uniformity on the breakout surface which reduces potential thermal stresses. The utilization of the time averaged data from combined magnetic resonance velocimetry (MRV) and concentration (MRC) experiments for designing improved trailing edge breakout film cooling is demonstrated.
Heat Transfer of a Rotating Rectangular Channel With a Diamond-Shaped Pin-Fin Array at High Rotation Numbers
Authors: Chang S. W. , Liou T.-M. , Lee T.-H.
Published: July 2013

This experimental study measured the detailed Nusselt numbers (Nu) distributions over two opposite leading and trailing walls of a rotating rectangular channel fitted with a diamond-shaped pin-fin array with radially outward flow for gas turbine rotor blade cooling applications. The combined and isolated effects of Reynolds (Re), rotation (Ro), and buoyancy (Bu) numbers on local and area-averaged Nusselt numbers (Nu and Nu¯) were examined at the test conditions of 5000 ≤ Re ≤ 15,000, 0 ≤ Ro ≤ 0.6, and 0.0007 ≤ Bu ≤ 0.31. The present infrared thermography method enables the generation of full-field Nu scans over the rotating end walls at the realistic engine Ro conditions as the first attempt to reveal the combined rotating buoyancy and Coriolis force effects on heat transfer properties. The selected heat transfer results demonstrate the Coriolis and rotating-buoyancy effects on the heat transfer performances of this rotating channel. Acting by the combined Coriolis and rotating buoyancy effects on the area-averaged heat transfer properties, the rotating leading and trailing area-averaged Nusselt numbers are modified, respectively, to 0.82–1.52 and 1–1.89 times the static channel references. A set of physically consistent empirical Nu¯ correlations was generated to permit the assessments of individual and interdependent Re, Ro, and Bu effects on the area-averaged heat transfer properties over leading and trailing end walls.
Cutting Force Prediction on Micromilling Magnesium Metal Matrix Composites With Nanoreinforcements
Authors: Liu Jian , Li Juan , Xu Chengying
Published: July 2013

Due to its light weight, high creep, and wear resistance, magnesium metal matrix composites (Mg-MMCs) with nanosized reinforcements are promising for various industrial applications, especially those with high volume fractions of reinforcements. The machinability of Mg-MMCs and related cutting process modeling are important to study. In this paper, an analytical cutting force model is developed to predict cutting forces of Mg-MMC reinforced with SiC nanoparticles in micromilling process. This model is different from previous ones by encompassing the behaviors of nanoparticle reinforcements in three cutting scenarios, i.e., shearing, ploughing, and elastic recovery. By using the enhanced yield strength in the cutting force model, three major strengthening factors are incorporated, including load-bearing effect, enhanced dislocation density strengthening effect, and Orowan strengthening effect. In this way, material properties, such as the particle size and volume fraction as significant factors affecting the cutting forces, are explicitly considered. To validate the model, experiments based on various cutting conditions using two types of end mills (diameters as 100 μm and 1 mm) were conducted on pure Mg, Mg-MMCs with volume fractions of 5 vol. %, 10 vol. %, and 15 vol. %. The experimental results show a good agreement with the predicted cutting force value.
Investigations Into Superhydrophobicity of a Soot Surface Attributed to Nano-Asperities
Authors: Ramachandran Rahul , Seetharaman Madhu , Sharma N. N.
Published: July 2013

Superhydrophobicity in nature is the result of multiscale (hierarchical) roughness which consists of nano-asperities superimposed on micrometer scale roughness. A low-cost superhydrophobic surface was prepared by depositing soot on Vaseline coated glass substrates. The surface was rapidly prepared without any sophisticated fabrication facilities. The surface exhibited a remarkably high water contact angle of 161 deg and a roll-off angle of 3 deg. Atomic force microscopy (AFM) of the surface was done which revealed a very rough surface. The roughness features with nano-asperities superimposed on micrometer scale roughness enhance the water repellency. The micrometer scale peaks on the surface support the water droplet in a Cassie–Baxter state with the nano-asperities sheltering a composite interface below the droplet. The work of adhesion for the surface was also low at 18 nJ. The study will enable easy preparation of a cost effective superhydrophobic surface.
Long-Term Stability of Residual Stress Improvement by Water Jet Peening Considering Working Processes
Authors: Hashimoto Tadafumi , Osawa Yusuke , Itoh Shinsuke , Mochizuki Masahito , Nishimoto Kazutoshi
Published: July 2013

To prevent primary water stress corrosion cracking (PWSCC), water jet peening (WJP) has been used on the welds of Ni-based alloys in pressurized water reactors (PWRs). Before WJP, the welds are machined and buffed in order to conduct a penetrant test (PT) to verify the weld qualities to access, and microstructure evolution takes place in the target area due to the severe plastic deformation. The compressive residual stresses induced by WJP might be unstable under elevated temperatures because of the high dislocation density in the compressive stress layer. Therefore, the stability of the compressive residual stresses caused by WJP was investigated during long-term operation by considering the microstructure evolution due to the working processes. The following conclusions were made: The compressive residual stresses were slightly relaxed in the surface layers of the thermally aged specimens. There were no differences in the magnitude of the relaxation based on temperature or time. The compressive residual stresses induced by WJP were confirmed to remain stable under elevated temperatures. The stress relaxation at the surface followed the Johnson–Mehl equation, which states that stress relaxation can occur due to the recovery of severe plastic strain, since the estimated activation energy agrees very well with the self-diffusion energy for Ni. By utilizing the additivity rule, it was indicated that stress relaxation due to recovery is completed during the startup process. It was proposed that the long-term stability of WJP under elevated temperatures must be assessed based on compressive stresses with respect to the yield stress. Thermal elastic–plastic creep analysis was performed to predict the effect of creep strain. After 100 yr of simulated continuous operation at 80% capacity, there was little change in the WJP compressive stresses under an actual operating temperature of 623 K. Therefore, the long-term stability of WJP during actual operation was analytically predicted.
An Experimental Study of Flow-Induced Vibration and the Associated Flow Perturbations in a Parallel Triangular Tube Array
Authors: Khalifa Ahmed , Weaver David , Ziada Samir
Published: July 2013

The results of an experimental investigation of the flow perturbations associated with tube vibrations along the interstitial flow path are presented. A parallel triangular tube array consisting of seven rows and six columns of aluminum tubes with a pitch ratio of 1.54 was studied. Measurements of the interstitial flow perturbations along the flow lane were recorded using a hot-wire anemometer while monitoring the tube vibration in the longitudinal and transverse directions. A single flexible tube located in the third row of a rigid array was instrumented with pressure transducers to monitor the surface pressure variations. The flow perturbation amplitude and phase with respect to the tube vibrations were obtained at a number of locations along the flow lane in the array. The effects of tube vibration amplitude and frequency, turbulence level, location of measurements, and mean gap velocity on the flow perturbation amplitude and relative phase were investigated. It is found that the flow perturbations are most pronounced at the point of flow separation from the tube and decay rapidly with distance from this point. It appears that the time delay between tube vibration and flow perturbation is associated with flow separation and vorticity generation from the vibrating tube.
Analysis of Ignition Behavior in a Turbocharged Direct Injection Dual Fuel Engine Using Propane and Methane as Primary Fuels
Authors: Polk A. C. , Gibson C. M. , Shoemaker N. T. , Srinivasan K. K. , Krishnan S. R.
Published: July 2013

Dual fuel engine combustion utilizes a high-cetane fuel to initiate combustion of a low-cetane fuel. The performance and emissions benefits (low NOx and soot emissions) of dual fuel combustion are well-known. Ignition delay (ID) of the injected high-cetane fuel plays a critical role in quality of the dual fuel combustion process. This paper presents experimental analyses of the ID behavior for diesel-ignited propane and diesel-ignited methane dual fuel combustion. Two sets of experiments were performed at a constant engine speed (1800 rev/min) using a four-cylinder direct injection diesel engine with the stock electronic conversion unit (ECU) and a wastegated turbocharger. First, the effects of fuel–air equivalence ratios (Фpilot ∼ 0.2–0.6 and Фoverall ∼ 0.2–0.9) on IDs were quantified. Second, the effects of gaseous fuel percent energy substitution (PES) and brake mean effective pressure (BMEP) (from 2.5 to 10 bars) on IDs were investigated. With constant Фpilot (>0.5), increasing Фoverall with propane initially decreased ID but eventually led to premature propane auto-ignition; however, the corresponding effects with methane were relatively minor. Cyclic variations in the start of combustion (SOC) increased with increasing Фoverall (at constant Фpilot) more significantly for propane than for methane. With increasing PES at constant BMEP, the ID showed a nonlinear trend (initially increasing and later decreasing) at low BMEPs for propane but a linearly decreasing trend at high BMEPs. For methane, increasing PES only increased IDs at all BMEPs. At low BMEPs, increasing PES led to significantly higher cyclic SOC variations and SOC advancement for both propane and methane. Finally, the engine ignition delay (EID), defined as the separation between the start of injection (SOI) and the location of 50% of the cumulative heat release, was also shown to be a useful metric to understand the influence of ID on dual fuel combustion. Dual fuel ID is profoundly affected by the overall equivalence ratio, pilot fuel quantity, BMEP, and PES. At high equivalence ratios, IDs can be quite short, and beyond a certain limit, can lead to premature auto-igniton of the low-cetane fuel (especially for a reactive fuel like propane). Therefore, it is important to quantify dual fuel ID behavior over a range of engine operating conditions.
Filter Cake Properties of Water-Based Drilling Fluids Under Static and Dynamic Conditions Using Computed Tomography Scan
Authors: Elkatatny Salaheldin , Mahmoud Mohamed , Nasr-El-Din Hisham A.
Published: July 2013

Previous studies considered the water-based drilling fluid filter cake as homogenous, containing one layer with an average porosity and permeability. The filter cake was recently proved to be heterogeneous, containing two layers with different properties (thickness, porosity and permeability). Heterogeneity of the filter cake plays a key role in the design of chemical treatments needed to remove the filter cake. The objectives of this study are to describe filter cake buildup under static and dynamic conditions, determine change in the filter medium properties, and obtain the local filtration properties for each layer in the filter cake. A high pressure high temperature (HPHT) filter press was used to perform the filtration process at 225 °F and 300 psi. A CT (computed tomography) scanner was used to measure the thickness and porosity of the filter cake. The results obtained from the CT scan showed that under static conditions, the formation of filter cake changed from compression to buildup; while under dynamic conditions, the filter cake was formed under continuous buildup. The CT results explained the changes in the thickness and porosity of each layer of the filter cake with time. The CT scans showed the change in the properties of the ceramic disk, such as porosity and permeability, which affect the calculation of the filter cake permeability. The change of the properties of the filter medium was ignored in previous studies.
Study of Freckles Formation During Directional Solidification Under the Influence of Single-Phase and Multiphase Convection
Authors: Chakraborty Prodyut R. , Dutta Pradip
Published: July 2013

Formation of freckles during directional solidification of hypereutectic aqueous ammonium-chloride in a bottom cooled cavity is studied numerically. The system studied is thermally stable but solutally unstable, which causes plume type convection and formation of channels in the growing solid mush. Solidification of hypereutectic solutions is usually characterized by detached and drifting solid crystals, thus resulting in multiphase convection. The numerical simulation is performed using a fixed grid single domain approach with single-phase and multiphase convection phenomena. For the multiphase convection modeling in the solidifying system under consideration, the mushy region is assumed to consist of an immobile coherent zone containing packed equiaxed crystals and a mobile noncoherent zone where the solid crystals are able to move. The two zones are demarcated by a critical solid fraction criterion, referred to as the coherency point. The overall effects of drifting solid phase on the freckles formation are compared with the results from conventional single-phase convection model.