bluuebunny/crossref_metadata_2025 huggingface dataset:
Transition Metal Solubilities in WC in Cemented Carbide Materials
Authors: Weidow Jonathan , Johansson Sven , Andrén Hans‐Olof , Wahnström Göran
Published: October 2010

Solubilities of different transition metals in WC in cemented carbides at around 1700 K were determined with atom probe tomography. Ta had the highest solubility, followed by Nb, Cr, and V, all with atom fractions in the 10−3 range. Ti and Mn showed lower, yet detectable, solubilities in the 10−6 or 10−5 range. Zr and Co solubilities were too low to be measured. The results were compared with the theoretically calculated solubilities using density functional theory. These calculations predicted that Ta, Nb, V, and Cr should have the highest solubility, all in the 10−4 or 10−3 range. Ti was predicted to have a lower solubility (10−5 range) and Co, Hf, and Zr even lower (10−8 or 10−7 range).
Differences in the perception of seven behaviour‐modifying techniques in paediatric dentistry by undergraduate students using lecturing and video sequences for teaching
Authors: Kalwitzki M. , Beyer C. , Meller C.
Published: October 2010

Whilst preparing undergraduate students for a clinical course in paediatric dentistry, four consecutive classes (n = 107) were divided into two groups. Seven behaviour‐modifying techniques were introduced: systematic desensitization, operant conditioning, modelling, Tell, Show, Do‐principle, substitution, change of roles and the active involvement of the patient. The behaviour‐modifying techniques that had been taught to group one (n = 57) through lecturing were taught to group two (n = 50) through video sequences and vice versa in the following semester. Immediately after the presentations, students were asked by means of a questionnaire about their perceptions of ease of using the different techniques and their intention for clinical application of each technique. After completion of the clinical course, they were asked about which behaviour‐modifying techniques they had actually used when dealing with patients. Concerning the perception of ease of using the different techniques, there were considerable differences for six of the seven techniques (P < 0.05). Whilst some techniques seemed more difficult to apply clinically after lecturing, others seemed more difficult after video‐based teaching. Concerning the intention for clinical application and the actual clinical application, there were higher percentages for all techniques taught after video‐based teaching. However, the differences were significant only for two techniques in each case (P < 0.05). It is concluded that the use of video based teaching enhances the intention for application and the actual clinical application only for a limited number of behaviour‐modifying techniques.
Expression of prion gene and presence of prion protein during development of mouse molar tooth germ
Authors: Khan Qalb‐E‐Saleem , Press Charles McL. , Sehic Amer , Landin Maria A. , Risnes Steinar , Osmundsen Harald
Published: October 2010

Khan Q‐E‐S, Press C McL, Sehic A, Landin MA, Risnes S, Osmundsen H. Expression of prion gene and presence of prion protein during development of mouse molar tooth germ. Eur J Oral Sci 2010; 118: 559–565. © 2010 Eur J Oral Sci

In order to gain insight into possible cellular functions of the prion protein (PrP) during normal development, the expression of Prnp (encoding the PrP) and the distribution of the PrP were studied in murine tooth germs. Expression of Prnp in the mouse first molar tooth germ was highly dynamic, increasing several‐fold during the secretory phase of odontogenesis, exhibiting a time‐course of expression similar to that of genes coding for other extracellular proteins [e.g. enamel matrix proteins (Amelx, Ambn, Enam), Aplp1, Clstn1, and Clu]. Western blot analysis suggested that the amounts of PrP and amyloid beta (A4) precursor‐like protein 1 (APLP1) in the tooth germ followed time‐courses similar to those of the corresponding mRNAs. Immunohistochemical studies of the distribution of PrP in murine molar and incisor tooth germs at embryonic day (E)18.5 suggested that this protein was located in the cervical loop, outer enamel epithelium, pre‐ameloblasts, and dental papilla. Different degrees of immunolabelling of pre‐ameloblasts on the mesial and distal aspects of a lower molar cusp may be related to different enamel configurations on the two aspects. It is concluded that the dynamic patterns of expression of Prnp, and of distribution of PrP, suggest that PrP may have functions during secretory odontogenesis, perhaps in relation to amelogenesis.
Resolution of a titanium implant fracture after a recurrent trauma
Authors: Cardoso Leandro de Carvalho , Luvizuto Eloá Rodrigues , Trevisan Carolina Lunardelli , Garcia Idelmo Rangel , Panzarini Sônia Regina , Poi Wilson Roberto
Published: October 2010

Abstract –  Post‐traumatic complications occasionally lead to tooth loss as well as the need for future implants. However, rehabilitation with endosseous osseointegrated implants does not protect the patient from the risk of suffering a new trauma. Implant fracture and the damage of the hexagon are post‐traumatic complications that guide the clinician to preparing a more intricate treatment plan. The authors present a clinical case of a recurrent trauma of maxillary implant fracture. The treatment plan was to remove the implants followed by autogenous bone grafting to correct the defect. Two titanium implants were replaced, followed by connective tissue graft after allowing complete the healing process of the bone graft to occur. In the postoperative period of 6 months, satisfactory results have been shown as regards soft and hard tissues wound healing.
Examination of a cognitive model of stress, burnout, and intention to resign for Japanese nurses
Authors: OHUE Takashi , MORIYAMA Michiko , NAKAYA Takashi
Published: October 2010

Aim:  A reduction in burnout is required to decrease the voluntary turnover of nurses. This study was carried out with the aim of establishing a cognitive model of stress, burnout, and intention to resign for nurses.

Methods:  A questionnaire survey was administered to 336 nurses (27 male and 309 female) who had worked for ≤5 years at a hospital with multiple departments. The survey included an evaluation of burnout (Maslach Burnout Inventory), stress (Nursing Job Stressor Scale), automatic thoughts (Automatic Thoughts Questionnaire‐Revised), and irrational beliefs (Japanese Irrational Belief Test), in addition to the intention to resign.

Results:  The stressors that affected burnout in the nurses included conflict with other nursing staff, nursing role conflict, qualitative workload, quantitative workload, and conflict with patients. The irrational beliefs that were related to burnout included dependence, problem avoidance, and helplessness. In order to examine the automatic thoughts affecting burnout, groups with low and high negative automatic thoughts and low and high positive automatic thoughts were established. A two‐way ANOVA showed a significant interaction of these factors with emotional exhaustion, but no significant interaction with depersonalization and a personal sense of accomplishment. Only the major effect was significant. The final model showed a process of “stressor → irrational beliefs → negative automatic thoughts/positive automatic thoughts → burnout”. In addition, a relationship between burnout and an intention to resign was shown.

Conclusion:  These results suggest that stress and burnout in nurses might be prevented and that the number of nurses who leave their position could be decreased by changing irrational beliefs to rational beliefs, decreasing negative automatic thoughts, and facilitating positive automatic thoughts.
Transcellular and paracellular pathways of transepithelial fluid secretion in Malpighian (renal) tubules of the yellow fever mosquitoAedes aegypti
Authors: Beyenbach K. W. , Piermarini P. M.
Published: October 2010

Isolated Malpighian tubules of the yellow fever mosquito secrete NaCl and KCl from the peritubular bath to the tubule lumen via active transport of Na+and K+by principal cells. Lumen‐positive transepithelial voltages are the result. The counter‐ion Cl−follows passively by electrodiffusion through the paracellular pathway. Water follows by osmosis, but specific routes for water across the epithelium are unknown. Remarkably, the transepithelial secretion of NaCl, KCl and water is driven by a H+V‐ATPase located in the apical brush border membrane of principal cells and not the canonical Na+,K+‐ATPase. A hypothetical cation/H+exchanger moves Na+and K+from the cytoplasm to the tubule lumen. Also remarkable is the dynamic regulation of the paracellular permeability with switch‐like speed which mediates in part the post‐blood‐meal diuresis in mosquitoes. For example, the blood meal the female mosquito takes to nourish her eggs triggers the release of kinin diuretic peptides that (i) increases the Cl−conductance of the paracellular pathway and (ii) assembles V1and V0complexes to activate the H+V‐ATPase and cation/H+exchange close by. Thus, transcellular and paracellular pathways are both stimulated to quickly rid the mosquito of the unwanted salts and water of the blood meal. Stellate cells of the tubule appear to serve a metabolic support role, exporting the HCO3−generated during stimulated transport activity. Septate junctions define the properties of the paracellular pathway in Malpighian tubules, but the proteins responsible for the permselectivity and barrier functions of the septate junction are unknown.
Increased electroretinogram a‐wave amplitude after intravitreal bevacizumab injection for neovascular age‐related macular degeneration
Authors: Skaat Alon , Solomon Arie , Moroz Iris , Hai Orit Vidne , Rechtman Ehud , Vishnevskia Dai Vicktoria , Rotenstreich Ygal
Published: October 2010

Purpose:  To assess the effect of bevacizumab (Avastin®), a vascular endothelial growth factor inhibitor, on retinal function by full‐field electroretinography (ERG) in patients with neovascular age‐related macular degeneration (AMD).

Design:  A prospective, nonrandomized, controlled interventional clinical trial.

Methods:  Twelve patients (aged 50−85) with neovascular AMD each received one unilateral intravitreal injection of bevacizumab 1.25 mg/0.05 ml as part of the standard management for choroidal neovascular AMD. Before and 1 month after injection, all patients underwent bilateral full‐field ERG scanning by a masked technician according to the ISCEV protocol, and their wave amplitudes were recorded. Untreated eyes served as controls. Scotopic responses were recorded at four incremental light intensities and photopic responses at two incremental light intensities. Changes in ERG‐amplitude responses were calculated. Repeated‐measures anova was used for data analysis.

Results:  Mean pre‐ and postinjection differences in a‐wave amplitudes between the incremental light intensities in injected eyes were significantly higher than in controls (15.92 versus 1.33 μV for scotopic responses and 4.97 versus −1.06 μV for photopic responses; p = 0.057 and p = 0.01, respectively). Mean b‐wave amplitudes in injected eyes were significantly higher than in controls for photopic responses (p = 0.048), but for scotopic responses, the difference between treated and untreated eyes was not significant (p = 0.23).

Conclusions:  Intravitreally injected bevacizumab improves both rod and cone functioning in patients with neovascular AMD, as demonstrated by the increase in the ERG a‐wave responses of these patients. Other measured ERG parameters yielded no significant photoreceptor toxicity.
Corneal endothelial cells 6–7 years following cataract surgery in patients with pseudoexfoliation syndrome
Authors: Østern Atle E. , Drolsum Liv
Published: October 2010

Purpose:  To assess the condition of the corneal endothelium an extended period after cataract surgery in eyes with and without pseudoexfoliation syndrome (PES).

Methods:  Forty‐six patients with PES who underwent cataract surgery in the Eye Department, Oslo University Hospital, in 2001 and 2002 were enrolled and compared to 101 matched controls without PES who had surgery in the same period. They were re‐examined 6–7 years following surgery with measurements taken of corneal endothelial cell density (ECD), pleomorphism, polymegathism and corneal thickness.

Results:  Mean ECD was 2024 ± 371 cells/mm2 in eyes with PES and 2144 ± 365 cells/mm2 in eyes without PES. The difference was not statistically significant. No significant difference in polymegathism and pleomorphism was noted. Mean corneal thickness was 543 and 547 μm in eyes with and without PES, respectively (not statistically significant). The presence of glaucoma in pseudoexfoliative eyes was not associated with endothelial cell changes.

Conclusion:  Six to 7 years following cataract surgery, no statistically significant differences were established in ECD, pleomorphism, polymegathism and corneal thickness in eyes with and without PES. No clinical signs of corneal decompensation were noted amongst the participants.
Intravitreal triamcinolone, bevacizumab and pegaptanib for occult choroidal neovascularization
Authors: Forte Raimondo , Cennamo Gilda , Finelli Marialuisa , Cesarano Ida , D’Amico Giuseppe , De Crecchio Giuseppe , Cennamo Giovanni
Published: October 2010

Acta Ophthalmol. 2010: 88: e305–e310

Purpose:  To evaluate best‐corrected visual acuity (BCVA) and foveal thickness (FT) changes in occult subfoveal choroidal neovascularization (CNV) from age‐related macular degeneration (AMD) after intravitreal bevacizumab (IVB, 1.25 mg/0.05 ml), pegaptanib (IVP, 0.3 mg/0.09 ml) and triamcinolone acetonide (IVTA, 4 mg/0.1 ml) injected on an as needed basis.

Methods:  Retrospective, interventional, comparative study. BCVA (Early Treatment Diabetic Retinopathy Study LogMAR) and FT by optical coherence tomography (OCT) were evaluated during 12 months from first treatment. Patients were retreated if signs of neovascular activity were still present on angiography or OCT.

Results:  Forty‐eight eyes received IVB, 43 eyes received IVP, 52 eyes received IVTA. BCVA and FT at baseline were 1.22 ± 0.49 LogMAR and 410.2 ± 41.83 μm in the IVB group, 1.25 ± 0.43 LogMAR and 452.3 ± 44.83 μm in the IVP group and 1.31 ± 0.4 LogMAR and 456.6 ± 48.27 μm in the IVTA group. BCVA and FT improved in the three groups during follow‐up. A significantly greater improvement of BCVA was present at month‐3, month‐6 and at month‐12 in the IVB and IVP groups (p = 0.01). Improvement of FT was greater in the IVTA group at month‐3 (p = 0.02), while it was greater in the anti‐Vascular Endothelial Growth Factor (VEGF) groups at month‐6 and month‐12 (p = 0.01). A postoperative increase of intraocular pressure was detected in 9/52 (17.3%) eyes treated with IVTA, and in two cases it was resistant to topical therapy.

Conclusion:  Intravitreal injection of anti‐VEGF drugs administered on an as needed basis for AMD‐related occult CNVs provided functional and anatomic improvement during 12 months of follow‐up.
Simvastatin Inhibits Glucose‐Stimulated Vascular Smooth Muscle Cell Migration Involving Increased Expression of RhoB and a Block of Ras/Akt Signal
Authors: Chan Kuei‐Chuan , Wu Cheng‐Hsun , Huang Chien‐Ning , Lan Kuang‐Ping , Chang Wen Chun , Wang Chau‐Jong
Published: October 2010

Background:Diabetic patients are at high risk to develop atherosclerotic cardiovascular disease and have a higher restenotic rate after percutaneous coronary intervention (PCI). Statins improve cardiovascular outcome and reduce restenosis after PCI by inhibiting proliferation and migration of vascular smooth muscle cells (VSMCs). But the effect of statins on diabetes without dyslipidemia was still not fully understood. Our previous study has demonstrated that simvastatin inhibits VSMC proliferation in high glucose status without dyslipidemia, inducing a G0/G1 phase cell cycle growth arrest by acting on multiple steps upstream of pRb, including inhibition of CDK2/4 expression and upregulation of p53, p21, p16, and p27.Method:Following our previous study, we investigated the mechanism of simvastatin inhibition of VSMC migration in a diabetes‐like model (A7r5 cells under high glucose conditions without dyslipidemia).Results:Under high glucose conditions, simvastatin dose‐dependently inhibited VSMC migration, decreased PI3K/Akt pathway activity, reduced c‐Raf and Ras expression, increased RhoB but not RhoA, Rac1, and Cdc2 expression, dose‐dependently inhibited MMP‐2, but not MMP‐9, activity, and dose‐dependently inhibited NF‐κB activity.Conclusion:The inhibition of VSMC migration under high glucose conditions was via two different pathways. The first pathway is mevalonate‐related but not RhoA protein‐related and involves suppression of Ras and PI3K/Akt signals. The second pathway is not mevalonate‐related and involves increasing RhoB expression directly.
Disruption of Coronary Vasomotor Function: The Coronary Spasm Syndrome
Authors: Moukarbel George V. , Weinrauch Larry A.
Published: October 2010

Abnormal coronary vasoconstriction, or coronary spasm, can be the result of several factors, including local and neuroendocrine aberrations. It can manifest clinically as a coronary syndrome and plays an important role in the genesis of myocardial ischemia. Over the past half century, coronary angiography allowed the in vivo demonstration of spasm in patients who fit the initial clinical description of the condition as reported by Prinzmetal et al. Several clinical, basic, and more recently, genetic studies have provided insight into the pathogenesis, manifestations, and therapy of this condition. It is not uncommonly encountered in patients with coronary syndromes and absence of clearly pathologic lesions on angiography. Provocation tests utilizing pharmacologic and nonpharmacologic stimuli combined with imaging (echocardiography or coronary angiography) can help make the correct diagnosis. The use of calcium channel blockers and long‐acting nitrates is currently considered standard of care and the overall prognosis appears to be good. The recent discovery of genetic abnormalities predisposing to abnormal spasm of the coronaries has stimulated interest in the development of targeted therapies for the management of this condition.
Quechua Sheepherders on the Mountain Plains of Wyoming: The (In)hospitality of U.S. Guest Worker Programs
Authors: Krögel Alison
Published: October 2010

Este artículo describe el contexto histórico y socioeconómico de los programas de trabajo temporal de los EEUU y los modelos de (in)migración peruana que han contribuido al empleo de pastores quechuas en los Estados Unidos. El pastor “invitado” y contratado por un ranchero “anfitrión,” enfrenta un desequilibrio de poder en el cual su estatus legal depende del cumplimiento del contrato establecido por un solo empleador. Siguiendo el concepto de hospitalidad elaborado por Derrida—que la describe como un aporía sin resolución—arguyo que los programas de trabajo temporal conducen a los pastores hacia una “trampa hospitalaria”; pues no entienden el lenguaje del contrato y, además, su estatus temporal y legal contribuye a la crónica ceguera de los legisladores ante las atroces condiciones de trabajo y vivienda. Los pastores relatan testimonios sobre las privaciones físicas y emocionales a las que se que enfrentan como “huérfanos” (wakchakuna) en planicies estadounidenses en donde el pastoreo carece de las creencias quechuas sobre las relaciones de reciprocidad entre los humanos, la tierra y los animales.
Memories of the “Old Aboriginal Dances”: The Toba and Mocoví Performances in the Argentine Chaco
Authors: Citro Silvia
Published: October 2010

Este artículo explora las transformaciones de los cantos‐danzas circulares hasta mediados del siglo XX, entre dos pueblos aborígenes del Chaco argentino: tobas y mocovíes. A partir de las memorias de estos pueblos, analizo sus “danzas antiguas” como performances culturales que combinan expresiones corporales, musicales, visuales y verbales, y que tienen la capacidad de representar y también de constituir ciertos aspectos de la vida social. Propongo que estas performances fueron acciones corporizadas significantes que formaron parte de las disputas de los performers por legitimar o transformar sus relaciones étnicas, de género e intergeneracionales. Y en la actualidad, su memoria aún juega un rol clave en estas relaciones sociales. De este modo, intento mostrar cómo el estudio de los cambios estéticos en las danzas puede desvelar aspectos menos visibles de los procesos socioculturales de los pueblos aborígenes, especialmente, cuando las danzas se convierten en un campo ambiguo y dinámico en el que tienen lugar los procesos de legitimación, empoderamiento y disputa.
Shamans and Shams: The Discursive Effects of Ethnotourism in Ecuador
Authors: Davidov Veronica M.
Published: October 2010

Han surgido nuevas formas mercantilizadas de chamanismo en las comunidades Kichwa debido a la nueva afluencia de turistas interesados en las culturas indígenas de la Amazonía Ecuatoriana. Los ritos chamanicos son populares entre los turistas porque representan sus fantasías de la alteridad cultural, pero los intercambios económicos entre turistas y chamanes plantean problemas de legitimidad y autenticidad. El turismo privilegia los aspectos performativos de chamanismo más que las tradiciones que tradicionalmente han definido al chamán. Como consecuencia de ello, las comunidades Kichwa han visto un surgimiento de “nuevos” chamanes, que están capacitados en la actuación chamánica y tienen acceso a las plantas alucinógenas que se utilizan en el rito, pero les falta la formación apropiada, tradicionalmente asociada con hacerse chamán. En este contexto, el significado y la legitimidad de la vocación chamánica se contesta y se construye tanto intercultural como intraculturalmente.
Discovering Aj Pop B'atz': Collaborative Ethnography and the Exploration of Q'eqchi' Personhood
Authors: Kistler S. Ashley
Published: October 2010

Este informe explora la relación entre el conocimiento histórico y el poder en San Juan Chamelco, Guatemala. En Chamelco, los q'eqchi' producen la historia regional por medio de cuentos de Aj Pop B'atz', quien protegió la comunidad q'eqchi' contra la invasión española en el siglo XVI. En 2006, fundé un grupo étnografico colaborativo para analizar los cuentos orales y un documento colonial. Nuestro análisis revela Aj Pop B'atz' como una parte vital de la vida contemporánea q'eqchi'. Este artículo propone que mis colegas utilicen Aj Pop B'atz' para construir la identidad q'eqchi' y fortalecer su papel en la historia guatemalteca. El descubrimiento de un texto colonial que documenta Aj Pop B'atz' da a mis colegas el poder para cambiar la historia oficial de Guatemala que ignora las contribuciones del pueblo q'eqchi'. De hecho, este informe examina las investigaciones colaborativas como un medio de la historicidad latinoamericana.
The Roles of Worker Expertise, Information Sharing Quality, and Psychological Safety in Manufacturing Process Innovation: An Intellectual Capital Perspective
Authors: Lee Jung Young , Swink Morgan , Pandejpong Temyos
Published: October 2010

This paper examines the roles of three elements of intellectual capital in implementing process innovations. Building upon prior literature, we develop a model describing how worker expertise, information sharing quality, and psychological safety work together as elements of the human, structural, and social dimensions of intellectual capital to influence the technical success of manufacturing process innovation (MPI) projects. Results of an analysis of data describing 179 MPI projects in US firms strongly support a multidimensional, process‐oriented view of intellectual capital's effects on MPI project technical performance. We also find that the incrementalness of an MPI project plays a moderating role over the relationship between worker expertise and MPI performance. Our study provides insights on how intellectual capital can be more effectively accumulated in a project environment.
Spectral characteristics of lunar impact melts and inferred mineralogy
Authors: TOMPKINS Stefanie , PIETERS Carlé M.
Published: October 2010

Abstract– Two suites of lunar impact melt samples have been measured in NASA’s Reflectance Experiment Laboratory (RELAB) at Brown University. Suite 1 comprises seven Apollo 17 crystalline impact melt breccias and seven quenched glass equivalents. Suite 2 is made up of 15 additional impact melt samples (from Apollo 12, 15, 16, and 17) which exhibit a range of textures and compositions related to cooling conditions and glass abundance. A few of these samples have cooled slowly and fully crystallized, and thus have the same spectral properties as igneous rocks of similar texture and composition; they cannot be uniquely distinguished without geologic context. However, most of the impact melts and melt breccias contain either quantities of quenched glass and/or have developed microcrystalline nonequilibrium textures with well‐defined, diagnostic spectral properties. The microcrystalline textures are associated with a distinctive 600 nm absorption feature, apparently due to submicroscopic ilmenite inclusions in a transparent host (typically fine‐grained plagioclase). The reflectance properties of these lunar sample suites contribute to and constrain the identification and characterization of impact melts in remote sensing data.
Prediction of Incompressible Turbulent Separating Flow
Authors: Pletcher R. H.
Published: October 2010

The predictions of several turbulence models are compared with experimental data for flows containing regions of recirculation using an inverse finite-difference method to solve the boundary layer equations. A new turbulence model which employs a one-dimensional transport equation for the outer layer length scale is seen to provide the best agreement with experimental measurements beyond separation. Use of the solution of a modeled form of the turbulence kinetic energy equation to supply a turbulence velocity scale in models resulted in no noticeable improvement in predictions over models which utilized purely algebraic and mean flow quantities to obtain this velocity scale.
First-Order Pump Surge Behavior
Authors: Rothe P. H. , Runstadler P. W.
Published: October 2010

This paper presents the results of an empirical study undertaken to assess the appropriateness and applicability of a simple, analytical model of pump-piping system flow instability. The analysis is used to describe behavior actually observed in a well defined, simple, pump-piping system. The frequency and amplitude of the flow oscillations observed during pump surge and the range of the pump-piping system characteristic parameters for which unstable flow oscillations occurred are in good agreement with the behavior predicted by the analysis. The results of this work provide a quantitative basis for investigating modifications to the lumped-parameter model in order to make it also appropriate for the analysis of more complex pump or compressor system. Although the analytical model displayed here is not new, a direct comparison of model predictions against similar measurements of first-order pump surge has not been published prior to this work.
Effect of Polymer Additives on Cavitation Development and Noise in Water Flow Through an Orifice
Authors: O¯ba R. , Ito¯ Y. , Uranishi K.
Published: October 2010

The cavitation behavior and the shock pressure were experimentally investigated in dilute aqueous solutions of polymer flowing through an orifice, and the following facts were observed: (i) Very small quantities of polymer additives effectively suppressed both the inception and the development of cavitation, (ii) nonspherical cavitation bubbles were observed at any polymer concentration tested here, and the nonsphericity tended to increase with concentration, (iii) the spectral frequencies of shock pressures were principally confined within the audio frequency range. With an increase in concentration, the energy of the pressures drastically decreased and the frequency range shifted downwards.
Transport of Oils as Oil-in-Water Emulsions
Authors: Zakin J. L. , Pinaire R. , Borgmeyer M. E.
Published: October 2010

Turbulent flow pressure drop measurements were made for various concentrated oil-in-water emulsions which exhibit non-Newtonian behavior. The effects of oil viscosity, temperature and oil concentration on specific energy loss were evaluated. Measured turbulent friction factors consistently fell below those predicted by the Dodge and Melzner friction factor correlation, probably due to viscoelastic effects of the emulsion. Several polymer and surfactant drag reducers were tested in these emulsions, and high molecular weight polyacrylamides were found to be the most effective in further reducing pumping energy losses. The effectiveness of the polymer additives decreased with time during pump circulation.
Free Shear Layer Behavior in Rotating Systems
Authors: Rothe P. H. , Johnston J. P.
Published: October 2010

Experiments are reported concerning turbulent separated flow downstream of a backward-facing step in a two-dimensional channel that was rotated at a steady rate about a spanwise axis. Reattachment distance is reported as a function of Reynolds number, rotation direction and number and passage aspect ratio. Extensive flow visualization films have been produced. It is demonstrated that turbulent motions in a free shear layer may be suppressed or enhanced by system rotation according to the sense of the rotation. Two-dimensional, spanwise vortices which have been observed in the free shear layer are found to be relatively insensitive to system rotation in the stabilizing direction. These vortices are believed to be important contributors to the high rates of free shear layer entrainment, even in stationary systems at moderate Reynolds numbers.
Laminar Throughflow of a Fluid Containing Particles Between Corotating Disks
Authors: Truman C. R. , Rice W. , Jankowski D. F.
Published: October 2010

The flow between corotating disks is the basic flow in multiple-disk turbomachinery and such turbomachinery can be used with possible advantage with dusty gases. An analysis is presented which models the steady laminar flow of a compressible or incompressible Newtonian fluid containing solid spherical particles in either radial inflow or radial outflow between smooth parallel corotating disks. The system of equations describing the flow of the two phases is rendered parabolic through the use of order-of-magnitude arguments allowed by the small disk spacing compared with the radial extent of the flow. The equations are expressed in finite difference form, then linearized, and solved by Gaussian elimination at each step of a marching procedure beginning at the entrance. Typical results for the distribution of pressure and of the velocity and density of each of the phases are presented.
Jet Pump Cavitation With Ambient and High Temperature Water
Authors: Kudirka A. A. , DeCoster M. A.
Published: October 2010

Cavitation characteristics of a jet pump were explored in tests with 80°C and 280°C water. A cavitation coefficient based on suction velocity and net suction head was used to correlate results. Results at low temperature compared well to results in literature. Results at high temperature and comparison of jet pump cavitation at low and high temperatures are the first to be reported as far as known. The jet pump was substantially less susceptible to cavitation at 280°C than at 80°C. The effects of cavitation, as indicated by drop-off in jet pump performance, vibration, and acoustic noise, were also much less severe at 280°C than at 80°C.
Laminar Compressible Flow Over a Stationary Disk in a Rotating Cylinder
Authors: Toren M. , Solan A.
Published: October 2010

The laminar isothermal compressible flow in a rotating cylinder with a stationary bottom is treated both numerically and by boundary layer matching. The numerical solution of the Navier-Stokes equations is based on a modified Cheng-Allen finite difference scheme. An approximate solution is obtained by matching boundary layers to an interior core. For sufficiently low Ekman numbers, the approximate and numerical solutions are in close agreement. The compressibility is shown to increase the angular velocity in the core and to decrease the meridional circulation. When the aspect ratio of the cylinder is increased, both the angular velocity in the core and the meridional circulation increase.
An Experimental Investigation of Flow Unsteadiness Generated by Transitory Stall In Plane-Wall Diffusers
Authors: Smith C. R. , Layne J. L.
Published: October 2010

The effects of flow unsteadiness introduced by transitory stall in plane-wall, subsonic diffusers have been investigated using air as the working fluid. The results indicate that diffuser flow unsteadiness is basically a low frequency phenomenon which appears to be a direct function of time varying stall blockage in the diffuser. Quantitative correlation of unsteadiness as a function of geometry indicates that diffuser unsteadiness behaves systematically and that a geometric region of maximum unsteadiness is definable.
A Fundamental Criterion for the Application of Rotor Casing Treatment
Authors: Greitzer E. M. , Nikkanen J. P. , Haddad D. E. , Mazzawy R. S. , Joslyn H. D.
Published: October 2010

An experimental investigation has been carried out on the influence of grooved casing treatment on the stall margin of a compressor rotor. Tests were conducted with two rotor builds having different solidities (but all other parameters identical) so that one of the rotors exhibited a wall, or casing, type of stall, while the other showed a blade stall. It was found that the casing treatment, when compared to the solid casing, was very effective in increasing the stall margin of the wall stall configuration, whereas there was little or no change in the stall point of the blade stall configuration. Detailed relative frame measurements of the rotor exit flow field were also taken as part of the program. These showed that in a wall stall situation, the use of casing treatment produced a substantial decrease in the relative total pressure defect, compared with the solid casing, while this was not true for the blade stall type of blading. The results of the experiments, both in overall measurements and in the detailed relative frame traverses, support the hypothesis that casing treatment is effective only in a situation in which a wall stall exists.
Two-Dimensional Laminar Flow in Elbows
Authors: Orlandi P. , Cunsolo D.
Published: October 2010

A finite difference procedure is employed to evaluate the primary flow field in two typical elbows. The first has an internal wall radius equal to the width; the internal radius of the second sharper elbow is equal to one half of the width. Two dimensional flow is assumed and a 20 by 20 grid network is employed in both cases. The field is transformed into a rectangular one by generalized curvilinear coordinates. Velocity profiles and streamline patterns are presented and discussed. In both cases the outflow attains the parabolic profile assumed for the inflow. The pressure distributions on the internal and external walls have been calculated.
Three-Dimensional Structure of a Nominally Planar Turbulent Boundary Layer
Authors: Furuya Y. , Nakamura I. , Osaka H.
Published: October 2010

This research is concerned with detailed experiments on spanwise nonuniformity of nominally planar turbulent boundary layers. Two procedures for eliminating spanwise nonuniformity are studied. One method is to remove the original, natural vortices by introducing additional ones arising from protuberances attached to the leading edge of a flat plate, and the other technique is by making the main flow entirely uniform. Effects of artificially controlled streamwise vortices on spanwise nonuniformity are examined. From these experiments, the process by which induced vortices cause nonuniformity of turbulent boundary layer characteristics in the spanwise direction is discussed.
Numerical Solutions of Nonsteady Two-Dimensional Transonic Flows
Authors: Couston M. , Angelini J. J.
Published: October 2010

An alternating-direction implicit algorithm is applied to solve an improved formulation of the low-frequency, small-disturbance, two-dimensional potential equation. Linear solutions are presented for oscillating trailing edge flaps, plunging and pitching flat-plate airfoils, and compared with results obtained by a doublet-lattice-method. Nonlinear calculations for both steady and unsteady flow problems are then compared with results obtained by using the complete Euler equations. The present procedure allows one to solve complex aerodynamic problems, including flows with shock waves.
Experimental Study of a Jet-Driven Helmholtz Oscillator
Authors: Morel Thomas
Published: October 2010

This paper describes an experimental study of a Helmholtz resonator driven by a round jet passing through it. This device, dubbed the jet-driven Helmholtz oscillator (JDHO), is a rigid chamber with two round openings located coaxially in two opposite walls, through which a jet is allowed to pass across the chamber. At certain jet velocities, jet instabilities couple with the Helmholtz resonance to produce very powerful chamber-pressure oscillations at a frequency slightly higher than the chamber Helmholtz frequency. The amplitude of these pressure oscillations may reach values of up to 5.6 times the jet dynamic pressure. Simultaneously, the exiting flow pulsates at the same frequency with an amplitude of up to 60 percent of the exit jet velocity, and a loud sound is emitted. The thrust of the present study was twofold: to determine the optimum range of geometrical parameters producing the maximum magnitudes, and to identify the mechanisms underlying the oscillator operation.
Drag on an Oscillating Airfoil in a Fluctuating Free Stream
Authors: Kottapalli S. B. R. , Pierce G. Alvin
Published: October 2010

An analytical study is presented regarding the unsteady skin friction drag of an oscillating airfoil exposed to a fluctuating free stream speed. Both laminar and turbulent conditions are covered in the analysis. The unsteady potential flow pressure and velocity distributions required for the subsequent boundary layer analysis are obtained by an approximate development. The time-dependent boundary layer is solved by a finite difference scheme. It was found that depending on the values of the phase difference between free stream fluctuations and airfoil oscillations, reduced frequency, and amplitude of free stream fluctuations, the drag can either lead or lag the free stream.
A Calculation Procedure for Three-Dimensional, Viscous, Compressible Duct Flow. Part II—Stagnation Pressure Losses in a Rectangular Elbow
Authors: Moore John , Moore Joan G.
Published: October 2010

Three-dimensional, turbulent flow is calculated in an elbow used by Stanitz for an experimental investigation of secondary flow. Calculated wall-static pressure distributions and distributions of stagnation-pressure loss, both spatial and as a function of mass-flow ratio, are in good agreement with Stanitz’ measurements, justifying the use of a relatively simple mixing-length viscosity model. The calculation procedure and the results of two-dimensional “inviscid” flow calculations used as the starting point for the present calculations are described in Part I of this paper. The computed flow field shows clearly the development of the passage vortices.
Experimental Investigation of Flow Resistance and Wall Shear Stress in the Interior Subchannel of a Triangular Array of Parallel Rods
Authors: Fakory M. , Todreas N.
Published: October 2010

A simulated model of a triangular array of rods with pitch to diameter ratio of 1.1 with air flow was used to study the hydraulic parameters of the liquid metal fast breeder reactor (LMFBR) fuel geometry. The wall shear stress distribution, static pressure distribution, turbulence intensity, and friction factor were measured in the central subchannel from Reynolds numbers of 4 × 103 to 36 × 103. Our results show that the maximum wall shear stress occurs at the largest flow area, the static pressure is not uniform around the rod periphery, there is no detectable presence of secondary flow from the wall shear stress measurements, and the friction factor derived from the measured wall shear stress is less than the common friction factor derived from pressure drop measurement.
Investigations of Pulsating Turbulent Pipe Flow
Authors: Kirmse R. E.
Published: October 2010

Measurements of velocities and pressure gradients in pulsating turbulent pipe flow are performed by means of a directionally sensitive Laser-Doppler Velocimeter and inductive pressure transducers. The desired accuracy of the instrumentation was confirmed by preliminary tests in turbulent pipe flow without pulsations and in laminar oscillating flow. The temporal and spatial velocity field in the pulsating turbulent pipe flow could be satisfactorily determined for the entire flow field with the exception of the region extremely close to the wall (y < 0.0065, where y expresses the ratio of wall distance to pipe radius). The results are discussed and compared with results of theoretical calculations.
An Experimental Study of Flow Over a Rectangular Body
Authors: Sam R. G. , Lessmann R. C. , Test F. L.
Published: October 2010

An experimental investigation has been performed to determine the surface pressure distribution on models of rectangular cross section in a two dimensional incompressible flow as a function of angle of attack and freestream velocity. Data were obtained at angles of attack from 0 deg where a separation bubble exists on both upper and lower surfaces, to 40 deg where the flow resembles that about a flat plate. Existing theoretical analyses appear adequate for predicting the nature of the flow given the angle of attack and aspect ratio and for predicting the pressure distribution if the flow is similar to that around an inclined flat plate. At the low angles of attack the pressure inside the separation bubble appears to follow a “universal” nondimensional plot and the flow after reattachment is turbulent. At higher angles a stagnation line exists on the upper surface and the flow is laminar. Extreme favorable pressure gradients at these angles lie in a range which has been found previously to inhibit the generation of turbulence.
Experimental Investigation of a Variable Geometry, Radial Ejector
Authors: Ng T. T. , Otis D. R.
Published: October 2010

A radial ejector with two degrees of geometric control is constructed and tested at pressures ranging from 0.7 to 1.5 atmospheres and entrainment ratios ranging from 0 to 2. Maximum efficiencies of 16 percent were obtained, and performance could be maintained over a range of pressures by changing the position of the “spool,” an element defining the nozzle contours and flow areas. This design offers potential for applications with varying pressure and flow conditions where feedback control systems can continuously adjust the ejector geometry for maximum performance.
Measurements Within Go¨rtler Vortices
Authors: Winoto S. H. , Dura˜o D. F. G. , Crane R. I.
Published: October 2010

Local measurements of stream wise velocity component have been made in the laminar boundary layer on the concave surface of a water channel, supported by flow visualization. Details of the naturally-occurring Go¨rtler vortex pattern are presented.
Economic Analysis and Life Cycle Assessment of Concrete Thermal Energy Storage for Parabolic Trough Power Plants
Authors: Laing D. , Steinmann W. D. , Viebahn P. , Gräter F. , Bahl C.
Published: October 2010

For parabolic trough power plants using synthetic oil as the heat transfer medium, the application of solid media sensible heat storage is an attractive option in terms of investment and maintenance costs. One important aspect in storage development is the storage integration into the power plant. A modular operation concept for thermal storage systems was previously suggested by DLR, showing an increase in storage capacity of more than 100%. However, in these investigations, the additional costs needed to implement this storage concept into the power plant, such as for extra piping, valves, pumps, and control, had not been considered. These aspects are discussed in this paper, showing a decrease in levelized energy costs with a modular storage integration of 2–3%. In a life cycle assessment a comparison of an AndaSol-I type solar thermal power plant with the original two-tank molten salt storage and with a “hypothetical” concrete storage shows an advantage of the concrete storage technology concerning environmental impacts. The environmental impacts of the hypothetical concrete based AndaSol-I decreased by 7%, considering 1 kW h of solar electricity delivered to the grid. Regarding only the production of the power plant, the emissions decreased by 9.5%.
Analysis and Design of a Paraffin/Graphite Composite PCM Integrated in a Thermal Storage Unit
Authors: Pokhrel R. , González J. E. , Hight T. , Adalsteinsson T.
Published: October 2010

The addition of latent heat storage systems in solar thermal applications has several benefits including volume reduction in storage tanks and maintaining the temperature range of the thermal storage. A phase change material (PCM) provides high energy storage density at a constant temperature corresponding to its phase transition temperature. In this paper, a high temperature PCM (melting temperature of 80°C) made of a composite of paraffin and graphite was tested to determine its thermal properties. Tests were conducted with a differential scanning calorimeter and allowed the determination of the melting and solidification characteristics, latent heat, specific heat at melting and solidification, and thermal conductivity of the composite. The results of the study showed an increase in thermal conductivity by a factor of 4 when the mass fraction of the graphite in the composite was increased to 16.5%. The specific heat of the composite PCM (CPCM) decreased as the thermal conductivity increased, while the latent heat remained the same as the PCM component. In addition, the phase transition temperature was not influenced by the addition of expanded graphite. To explore the feasibility of the CPCM for practical applications, a numerical solution of the phase change transition of a small cylinder was derived. Finally, a numerical simulation and the experimental results for a known volume of CPCM indicated a reduction in solidification time by a factor of 6. The numerical analysis was further explored to indicate the optimum operating Biot number for maximum efficiency of the composite PCM thermal energy storage.
On the Regulus Associated With the General Displacement of a Line and Its Application in Determining Displacement Screws
Authors: Huang Chintien , Kuo Wuchang , Ravani Bahram
Published: October 2010

In the two position theory of finite kinematics, we are concerned with not only the displacement of a rigid body, but also with the displacement of a certain element of the body. This paper deals with the displacement of a line and unveils the regulus that corresponds to such a displacement. The regulus is then used as a basic entity to determine the displacements of a rigid body from line specifications. Residing on a special hyperbolic paraboloid, the regulus is obtained by the intersection of three linear line complexes corresponding to a specific set of basis screws of a three-system. When determining the displacements of a rigid body from line specifications, a displacement screw is obtained by fitting a linear line complex to two or more line reguli. When two exact pairs of homologous lines are specified, we obtain a unique linear line complex, which determines the corresponding displacement screw. When more than two pairs of homologous lines with measurement errors are specified, it becomes a redundantly specified problem, and a linear line complex that has the best fit to more than two reguli is determined.