bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Porphyromonas gingivalis infection on human gingival epithelial barrier function in vitro
Authors: Groeger Sabine , Doman Eugen , Chakraborty Trinad , Meyle Jörg
Published: October 2010

Groeger S, Doman E, Chakraborty T, Meyle J. Effects of Porphyromonas gingivalis infection on human gingival epithelial barrier function in vitro. Eur J Oral Sci 2010; 118: 582–589. © 2010 Eur J Oral Sci

The gingival epithelium plays an important role in the protection of oral tissues from microbial challenge. Oral keratinocytes form various cellular contacts, including tight junctions, and thus are able to create an epithelial barrier. A measurable indicator of barrier function in vitro is the transepithelial electrical resistance (TER). Porphyromonas gingivalis is recognized as a major aetiologic agent of periodontal disease and exhibits a variety of virulence factors. The aim of the study was to investigate the effect, in vitro, of infection with P. gingivalis on gingival barriers composed of primary and immortalized human keratinocytes. Primary and immortalized human gingival keratinocytes were infected with different strains of P. gingivalis. The impact of the bacterial challenge on the barrier was analysed by measuring the TER. The destructive effects of gingipains were blocked by specific enzyme inhibitors. After an initial increase of about 20–30% in infected wells, the TER decreased to zero. Gingipain inhibitors delayed the destruction of the barrier by 12 ± 4 h. In all cases, the loss of TER was accelerated if the system was infected from the basolateral side. A distinct effect of P. gingivalis on the epithelial barrier function of three‐dimensional cultured epithelial cell models was demonstrated, which can partly be attributed to the activity of gingipains.
A retrospective study of 889 injured permanent teeth
Authors: Hecova Hana , Tzigkounakis Vasileios , Merglova Vlasta , Netolicky Jan
Published: October 2010

Abstract –  The aim of this study was to investigate pre‐injury factors, causes of dental injuries and healing complications after traumatic injuries to permanent teeth. The analysed sample comprised 889 permanent teeth of 384 patients, who were treated in the Dentistry Department in Faculty Hospital in Pilsen. Enamel‐dentin fractures [233 teeth (26.2%)] and lateral luxations [207 teeth (23.3%)] were the most frequent injuries. The age of the patients at the time of injury varied between 7 and 65 years. Predominantly, children were affected [587 injured teeth (66.0%)]. The most frequent causes of injuries in patients older than 11 years were various sport activities, predominantly bicycling. Pulp necrosis was observed in 239 teeth (26.9%). It was the most frequent post‐traumatic complication in all types of dental traumas. Teeth with a completed root formation demonstrated a higher prevalence of pulp necrosis than teeth with an incomplete root formation in all types of luxation injuries. External root resorption was observed in 144 teeth. The rate of inflammatory resorption differed between the various types of luxation injuries (extrusive luxation 5.6%, lateral luxation 11.6%, intrusive luxation 33.3%). Following avulsion and replantation, active inflammatory resorptions were diagnosed in 13 (26.5%) of 49 replanted teeth and ankylosis/replacement resorptions were observed in 21 (42.9%) of 49 replanted teeth. After avulsion, primarily, immature teeth were affected by these complications. Within the observation period of 5 years, 39 teeth (4.4%) had to be removed (16 teeth with root fractures, 19 avulsed and replanted teeth, 3 luxated teeth, 1 tooth with crown‐root fracture).
Effect of HBSS storage time on human periodontal ligament fibroblast viability
Authors: De Souza Beatriz Dulcineia Mendes , Bortoluzzi Eduardo Antunes , Da Silveira Teixeira Cleonice , Felippe Wilson Tadeu , Simões Cláudia Maria Oliveira , Felippe Mara Cristina Santos
Published: October 2010

Abstract –  Hank’s balanced salt solution (HBSS) is recommended for the storage of avulsed teeth. The objective of this study was to evaluate if the HBSS storage time influences its ability to maintain the viability of human periodontal ligament fibroblasts (PDLF) by the analysis of cell metabolic function using MTT assay. PDLF were kept at 20°C for 3, 6, 24, 48, 72, 96 and 120 h in recently prepared HBSS (HBSS), HBSS stored for 6 months (HBSS 6 M), HBSS stored for 12 months (HBSS 12 M), and in Save‐A‐Tooth system’s HBSS (Save). Minimum essential medium (MEM) at 37°C and tap water at 20°C served as positive and negative controls, respectively. Cell viability was determined by the tetrazolium salt‐based colorimetric (MTT) assay. Data were statistically analyzed by the Kruskal–Wallis and Scheffé tests (α = 5%). Starting with the 6 h time‐point, HBSS was significantly more effective than HBSS 6 M, HBSS 12 M and Save in maintaining cell viability. HBSS 6 M effectiveness was similar to that of HBSS 12 M for up to 48 h, becoming higher at 72 h. In conclusion, the storage time of HBSS had a negative influence on its ability to maintain PDLF viability.
Marathon of eponyms: 14 Noonan syndrome
Authors: Scully C , Langdon J , Evans J
Published: October 2010

Oral Diseases (2010) 16, 839–840

The use of eponyms has long been contentious, but many remain in common use, as discussed elsewhere (Editorial: Oral Diseases. 2009: 15; 185). The use of eponyms in diseases of the head and neck is found mainly in specialties dealing with medically compromised individuals (paediatric dentistry, special care dentistry, oral and maxillofacial medicine, oral and maxillofacial pathology, oral and maxillofacial radiology and oral and maxillofacial surgery) and particularly by hospital‐centred practitioners. This series has selected some of the more recognised relevant eponymous conditions and presents them alphabetically. The information is based largely on data available from MEDLINE and a number of internet websites as noted below: the authors would welcome any corrections. This document summarises data about Noonan syndrome.
Severe reactions after the intake of soy drink in birch pollen‐allergic children sensitized to Gly m 4
Authors: Kosma Paraskevi , Sjölander Sigrid , Landgren Eva , Borres Magnus P , Hedlin Gunilla
Published: October 2010

Aim: To study the connection between reaction to soy milk and IgE sensitization to Gly m 4.

Methods: Four subjects who experienced unforeseen and severe symptoms after the ingestion of soymilk were studied.

Results: All children were birch pollen allergic, had high IgE responses to the PR‐10 proteins from birch and soybean, Bet v 1 and Gly m 4. All reactions took place after the ingestion of soymilk during the peak pollen season.

Conclusion: This is the first time soybean‐dependant pollen‐food cross‐reaction has been reported in children experiencing reactions during the birch pollen season. These findings may well be helpful to doctors in identifying individuals at risk of severe reactions upon the ingestion of soymilk, and we foresee an increase in the number of similar cases as soy drinks are promoted for health purposes.
Conservation of the egg envelope digestion mechanism of hatching enzyme in euteleostean fishes
Authors: Kawaguchi Mari , Yasumasu Shigeki , Shimizu Akio , Sano Kaori , Iuchi Ichiro , Nishida Mutsumi
Published: October 2010

We purified two hatching enzymes, namely high choriolytic enzyme (HCE; EC 3.4.24.67) and low choriolytic enzyme (LCE; EC 3.4.24.66), from the hatching liquid of Fundulus heteroclitus, which were named Fundulus HCE (FHCE) and Fundulus LCE (FLCE). FHCE swelled the inner layer of egg envelope, and FLCE completely digested the FHCE‐swollen envelope. In addition, we cloned three Fundulus cDNAs orthologous to cDNAs for the medaka precursors of egg envelope subunit proteins (i.e. choriogenins H, H minor and L) from the female liver. Cleavage sites of FHCE and FLCE on egg envelope subunit proteins were determined by comparing the N‐terminal amino acid sequences of digests with the sequences deduced from the cDNAs for egg envelope subunit proteins. FHCE and FLCE cleaved different sites of the subunit proteins. FHCE efficiently cleaved the Pro‐X‐Y repeat regions into tripeptides to dodecapeptides to swell the envelope, whereas FLCE cleaved the inside of the zona pellucida domain, the core structure of egg envelope subunit protein, to completely digest the FHCE‐swollen envelope. A comparison showed that the positions of hatching enzyme cleavage sites on egg envelope subunit proteins were strictly conserved between Fundulus and medaka. Finally, we extended such a comparison to three other euteleosts (i.e. three‐spined stickleback, spotted halibut and rainbow trout) and found that the egg envelope digestion mechanism was well conserved among them. During evolution, the egg envelope digestion by HCE and LCE orthologs was established in the lineage of euteleosts, and the mechanism is suggested to be conserved.
Comparison of Chlorophyll and Photosynthesis Parameters of Floating and Attached Ulva prolifera
Authors: Lin Apeng , Shen Songdong , Wang Guangce , Yi Qianqian , Qiao Hongjin , Niu Jianfeng , Pan Guanghua
Published: October 2010

In mid‐May 2008 a serious green tide caused mainly by floating Ulva prolifera (Müller) J. Agardh (Chlorophyta, Ulvales) thalli struck the coastal area of Qingdao, China. To understand the present physiological conditions of the floating alga, in this work both laboratory and field investigations were conducted on the floating U. prolifera thalli in comparison with the attached U. prolifera thalli collected from the area. The floating thalli of three distinctively different colors and attached thalli at three different stages of sporangium formation process were characterized under a microscope, while their photosynthetic parameters were determined with chlorophyll fluorescence technology. On the other hand, the sporangium formation status of the floating U. prolifera thalli was surveyed both in the laboratory and in the field. Comparisons showed that both of the paired morphological characteristics and the paired physiological parameters of the floating and attached U. prolifera thalli were consistent. Furthermore, some spores were confirmed in the field and some motile particles were found within the floating thalli. These results suggest that the floating U. prolifera thalli with different colors could be at different stages of sporangium formation. However, our results also showed that the floating alga thalli have only a limited reproductive potential. This might limit the duration and the further geographic expansion of the green algal bloom.
How to weigh a star using a moon
Authors: Kipping David M.
Published: October 2010

We show that for a transiting exoplanet accompanied by a moon which also transits, the absolute masses and radii of the star, planet and moon are determinable. For a planet–star system, it is well known that the density of the star is calculable from the light curve by manipulation of Kepler's Third Law. In an analogous way, the planetary density is calculable for a planet–moon system which transits a star, and thus the ratio-of-densities is known. By combining this ratio with the observed ratio-of-radii and the radial velocity measurements of the system, we show that the absolute dimensions of the star and planet are determinable. This means such systems could be used as calibrators of stellar evolution. The detection of dynamical effects, such as transit timing variations, allows the absolute mass of the moon to be determined as well, which may be combined with the radius to infer the satellite's composition.
Histomorphometry of the circular peripapillary arterial ring of Zinn–Haller in normal eyes and eyes with secondary angle‐closure glaucoma
Authors: Jonas Jost B. , Jonas Shefali B.
Published: October 2010

Acta Ophthalmol. 2010: 88: e317–e322

Purpose:  To examine the location and size of the peripapillary arterial circle of Zinn–Haller (PACZH) and its associations with other eye measures in normal eyes and eyes with secondary angle‐closure glaucoma.

Methods:  The study included 29 human globes enucleated because of malignant choroidal melanoma (n = 19) (control group) or because of secondary angle‐closure glaucoma (n = 10). Anterior–posterior histological sections were morphometrically evaluated.

Results:  The PACZH was present in all eyes. The glaucoma group and the control group did not vary significantly in the distance from the PACZH to Bruch’s membrane (297 ± 67 versus 270 ± 67 μm; p = 0.29), optic disc border (281 ± 103 versus 391 ± 170 μm; p = 0.07), optic disc centre (1059 ± 191 versus 978 ± 205 μm; p = 0.30) and retrobulbar cerebrospinal fluid space (173 ± 58 versus 172 ± 81 μm; p = 0.97) nor in the minimal PACZH diameter (39 ± 18 versus 36 ± 18 μm; p = 0.74) and maximal PACZH diameter (78 ± 37 versus 65 ± 25 μm; p = 0.36). The PACZH location, measured as distance from Bruch’s membrane, disc border, disc centre and cerebrospinal fluid space, was not significantly associated with axial length (p > 0.39), horizontal globe diameter (p > 0.17) and vertical globe diameter (p > 0.22). Both diameters were statistically independent of axial length (p = 0.72 and p = 0.58, respectively), horizontal globe diameter (p = 0.60 and p = 0.41, respectively) and vertical globe diameter (p = 0.64 and p = 0.52, respectively). All parameters were statistically independent of age (p > 0.10) and gender (p > 0.10).

Conclusions:  The PACZH was present in all human eyes examined and did not vary significantly in location and diameter between eyes with secondary angle‐closure glaucoma and nonglaucomatous eyes, nor between myopic versus hyperopic eyes.
MicroRNA‐Based Therapeutic Approaches in the Cardiovascular System
Authors: Fiedler J. , Gupta S. K. , Thum T.
Published: October 2010

MicroRNAs (miRNAs) are endogenous small ribonucleotides that participate in the orchestration of the genome by regulating target messenger RNA translation. MiRNAs control physiological processes and misexpression of miRNAs is pathogenically involved in many diseases including cardiovascular diseases. Normalization of miRNA expression and thus downstream target networks may have enormous therapeutic chances but also risks. We here highlight and discuss recent advances in the development and use of miRNA therapeutics to target miRNAs in vivo that may translate into novel therapeutic strategies for cardiovascular diseases in the future.
TREK‐1 K+Channels in the Cardiovascular System: Their Significance and Potential as a Therapeutic Target
Authors: Goonetilleke Lakshman , Quayle John
Published: October 2010

Potassium (K+) channels are important in cardiovascular disease both as drug targets and as a cause of underlying pathology. Voltage‐dependent K+(KV) channels are inhibited by the class III antiarrhythmic agents. Certain vasodilators work by opening K+channels in vascular smooth muscle cells (VSMCs), and K+channel activation may also be a route to improving endothelial function. The two‐pore domain K+(K2P) channels form a group of 15 known channels with an expanding list of functions in the cardiovascular system. One of these K2Pchannels, TREK‐1, is the focus of this review. TREK‐1 channel activity is tightly regulated by intracellular and extracellular pH, membrane stretch, polyunsaturated fatty acids (PUFAs), temperature, and receptor‐coupled second messenger systems. TREK‐1 channels are also activated by volatile anesthetics and some neuroprotectant agents, and they are inhibited by selective serotonin reuptake inhibitors (SSRIs) as well as amide local anesthetics. Some of the clinical cardiovascular effects and side effects of these drugs may be through their actions on TREK‐1 channels. It has recently been suggested that TREK‐1 channels have a role in mechano‐electrical coupling in the heart. They also seem important in the vascular responses to PUFAs, and this may underlie some of the beneficial cardiovascular effects of the essential dietary fatty acids. Development of selective TREK‐1 openers and inhibitors may provide promising routes for intervention in cardiovascular diseases.
Unfractionated Heparin during Elective PCI: Fixed Dose or Weight Adjusted?
Authors: Kidambi Ananth , Mayurathan Gnanamoorthy , Viswanathan Girish , Schechter Clyde , Zaman Azfar G.
Published: October 2010

Introduction: To assess two different dosing strategies of unfractionated heparin (UFH) during elective percutaneous coronary intervention (PCI). Aims: The optimal dose of heparin during elective PCI in patients with stable angina is unknown. Existing guidelines are based on limited data. We interrogated data from the PCI database. Patients with stable angina undergoing planned transradial PCI for uncomplicated single lesions were included. The main endpoint was troponin I release. We compared a fixed heparin dose (3000 U) UFH to a weight‐adjusted dose. Results: Of 698 patients 244 (35.0%) received fixed dose (3000 U) and 454 (65.0%) 70 U/kg weight‐adjusted UFH. There was no significant difference in median troponin between the fixed dose and the weight‐adjusted groups; 0.17 ng/mL versus 0.14; P= 0.21. The proportion of troponin positive patients was similar in both groups (61.9% in the fixed dose group vs. 58.1%; P= 0.37). There were no deaths or major ischemic events during hospitalization. There was no bleeding requiring transfusion or delaying hospital discharge. Conclusion: In conclusion, this retrospective observational study of elective transradial PCI demonstrated that a reduced, fixed dose of periprocedural heparin was associated with similar postprocedural troponin levels when compared to a standard weight‐adjusted regime. Our study further questions the optimal dose of heparin required during elective PCI and suggests a need for further trials.
Questions of Indigeneity and the (Re)‐Emergent Ch'orti' Maya of Honduras
Authors: Metz Brent
Published: October 2010

Entre el espacio de unos años, los Ch'orti'de Honduras salieron de una identidad débil y vergonzosa a tener un movimiento étnico con miles de miembros y tan fuerte que apresuró el gobierno nacional. La volatilidad de tal identidades en la época de derechos y reparaciones indígenas exige un análisis que reconozca la construcción social de identidades de grupos, pero atención única a procesos de construcción de corto plazo es impracticable y engañadora. La gente utiliza cultura existente para reconocer y fortalecer fronteras étnicas. Tal cultura y las identidades que moldea es evidencia clave en decidir si los demandantes indígenas son legítimas, o si están aprovechándose de recursos mejor destinados a otros.
The Owner of the Hill: Masculinity and Drug‐trafficking in Rio de Janeiro, Brazil
Authors: Penglase Ben
Published: October 2010

Este artículo investiga el modo en que los traficantes de drogas de Rio Janeiro, Brasil, usan un discurso ideológico de autoridad masculina para estructurar sus relaciones con los residentes de las favelas en esa ciudad. El artículo muestra cómo el discurso en torno al “respeto” permite a los traficantes la legitimación de su propia influencia sobre los habitantes de las favelas, la normalización de la desigualdad y el silenciamiento de la oposición. También muestra por qué los residentes de las favelas aceptan este tipo de discursos de autoridad y examina como estos residentes, a su vez, usan el discurso de género en su intento de negociar la relación con los traficantes de drogas. Sin embargo, los traficantes también alteran la relación entre la masculinidad y la asignación de los diferentes grados de vulnerabilidad. Además el artículo muestra como este tipo de relación genera una experiencia desestabilizadora de ansiedad para los hombres de las favelas que no participan en el tráfico de droga. En general, sostengo que hasta que el análisis de la violencia urbana no se sitúe dentro de un contexto que tenga en cuenta el género, la misma no podrá ser completamente entendida.
De los derechos de los adoptantes al derecho a la identidad: los procedimientos de adopción y la apropiación criminal de niños en la Argentina
Authors: Villalta Carla
Published: October 2010

En este artículo se revisan dos reformas, introducidas en la Argentina a principios de la década del ‘70 y a fines de los años ‘90, con el fin de regular la adopción de niños. En estos contextos históricos, se examinan los sentidos que primaron tanto sobre el vínculo adoptivo, como respecto del papel del Estado en la gestión del parentesco legal. Desde esta perspectiva, se analiza el impacto que tuvieron la apropiación criminal de niños, desarrollada durante el terrorismo de estado (1976–1983) como un “evento crítico” (Das 1995), y las estrategias desplegadas por Abuelas de Plaza de Mayo para lograr la restitución de sus nietos, en los debates y la forma en la que se definió la figura legal de la adopción y las facultades otorgadas a los organismos judiciales y administrativos para concederla.
Getting an Attitude: Brazilian Hip Hoppers Design Gender
Authors: Pardue Derek
Published: October 2010

En este ensayo demuestro que loship hoppersbrasileños están interesados en las cuestiones de género. Ellos están deseosos de representar y explícitamente conectar “técnicas” y “actitud”, sus objectivos estéticos en el hip hop, a aquéllos de carácter social, como la demarcación de las nociones contemporáneas de masculinidad y femininidad. Para abordar el significado de actuaciones tan populares, contextualizo el hip hop dentro de los parámetros históricos e ideológicos del patriarcado y del machismo en el Brasil urbano. Argumento que, a diferencia de otras categorías sociales como raza, clase y lugar, el género se mantiene como un elemento discursivo relativamente conservador para los hip hoppers brasileños. A pesar de ello, ha emergido una dinámica productiva en relación a la representación de género al interior de los varios sub‐estilos del hip hop brasileño, y con ella un cambio potencial en la formación hegemónica del machismo en la cultura popular y urbana.
The Strange and the Native: Ritual and Activism in the Aymara Quest for Decolonization
Authors: Burman Anders
Published: October 2010

El fenómeno de pérdida de espíritu está ampliamente difundido en los Andes bolivianos. Por razones de susto, una persona pierde su espíritu y un espíritu “extraño” puede llegar a reemplazarlo causando enfermedad. En un mismo padecimiento, entonces, se encuentran nociones de “pérdida” e “imposición”. Asimismo, en el contexto de “indigeneidades emergentes” se conceptualiza a menudo el colonialismo como un proceso de “pérdida” e “imposición”; pérdida de identidades “nativas”, imposición de identidades “extrañas”. El presente artículo plantea que estudiar las prácticas rituales aymaras de curación puede ser una manera de llegar a entender el activismo indígena y viceversa. Se identifican y examinan ciertas premisas que subyacen por igual en las prácticas rituales y el activismo y se explora el entrelazamiento entre ambas prácticas, planteando que el activismo indígena sería mejor entendido si se tienen en cuenta nociones cosmológicamente incrustadas de “lo propio” y “lo extraño” y prácticas rituales de relacionamiento con “lo extraño”.
A Wind-Tunnel Study of the Effect of Gap Flow and Gap Seals on the Aerodynamic Drag of Tractor-Trailer Trucks
Authors: Buckley F. T. , Marks C. H.
Published: October 2010

The effect of gap width on the aerodynamic drag of a cab-over-engine tractor-trailer combination has been investigated for full-scale gap widths ranging from 0.61 m (24 in) to 1.83 m (72 in.) over a yaw angle range of 0 to 20 deg. The average drag on the vehicle was found to increase by 16 percent as the gap width increased from 0.61 m to 1.83 m. Drag reductions were found when a vertical seal was placed along the vehicle center line between the tractor and the trailer. Generally, the drag reduction increased as the percentage of gap width that was sealed increased, and as the yaw angle increased. The average drag coefficient reduction provided by a full gap seal increased from 0.02 to 0.05 as the gap width increased from 0.61 m to 1.4 m and then decreased slightly for gap widths up to 1.83 m. The effect of vehicle configuration on gap seal effectiveness was evaluated for a gap width of 1.3 m (51 in.) using models of six different tractors and two different trailers. The average drag coefficient reductions that were found ranged from 0.04 to 0.08 with 83 percent of the data being either 0.04 or 0.05. It is shown that the use of gap seals on the nearly half-million vehicles which comprise the nation’s long-haul trucking fleet can result in the conservation of about 1.4 × 109 liters (0.37 × 109 gal) of motor fuel each year.
A Study of the Base Drag of Tractor-Trailer Trucks
Authors: Marks C. H. , Buckley F. T. , Walston W. H.
Published: October 2010

Measurements were made of the base pressure distribution and the aerodynamic drag of a variety of 1/8th-scale tractor-trailer truck models in a wind tunnel at yaw angles ranging from 0° to 20°. Base-drag coefficients and overall aerodynamic-drag coefficients were calculated from this data. The measurements show that the base-drag coefficient of typical tractor-trailer trucks does not vary much with vehicle configuration, and that base drag constitutes approximately 13 to 15 percent of the total aerodynamic drag at zero yaw. The base drag increases in magnitude and also becomes a larger part of the overall aerodynamic drag as yaw angle increases, reaching about 18 to 25 percent of the overall drag at 20° yaw. Streamlining the forebody of the vehicle has little effect on the base-drag coefficient, but increases the fraction of the overall aerodynamic drag due to the base.
Particle Deposition in a Charged Aerosol Flowing Through a Conducting Tube
Authors: Savilonis B. J. , Lee J. S.
Published: October 2010

A mathematical analysis is presented for charged aerosol flowing in an infinitely long, cylindrical, conducting tube. The aerosol is assumed to move in “plug” flow and to be dilute, unipolar, and of uniform size and charge. Repulsion due to the particle space charge is the only mode of deposition considered. Ignoring particle inertia, numerical results indicate that Wilson’s equation yields a good approximation for concentration as a function of axial distance. Solutions obtained when particle mass is considered indicate the importance of radial inertia.
Gas Flow Through Cracks
Authors: Button B. L. , Grogan A. F. , Chivers T. C. , Manning P. T.
Published: October 2010

Nitrogen flow through 13 idealized cracks has been measured and compared with theoretical predictions. Gas conditions covered upstream pressure and temperature ranges of between 10 and 50 bars and 277 and 295°K, respectively, exhausting to atmosphere. Hydraulic smooth, convergent and parallel cracks and rough parallel cracks were tested for depths varying from 6 to 810 μm. The effect of area change is adequately predicted from theory if a friction factor Reynolds number relationship is assumed. The remaining data are presented on the basis of a friction factor, Reynolds number, and hydraulic diameter/surface roughness parameter basis. Theoretical predictions are successful where roughness and flow are high enough for the results to be in the completely turbulent regimes. For the hydraulic smooth parallel cracks the flow is lower than predicted for laminar and turbulent flow and this discrepancy will be the subject for further investigations.
An Integral Method for Calculating Turbulent Boundary Layer With Separation
Authors: Assassa G. M. , Papailiou K. D.
Published: October 2010

A two-equation energy integral boundary layer method is presented for the calculation of separation and of slightly separated boundary layers. The method is a direct one and is capable of passing through separation without making use of an interaction equation. Comparison with experiments shows that wall curvature effects on turbulence and the taking into account of the normal fluctuation terms in the equations are essential elements for the accurate calculation of the behavior of a boundary layer in the vicinity of separation.
Observation of Flow in a Ring Inlet Chamber
Authors: Merkli P. , Escudier M. P.
Published: October 2010

We present the results of visualization and quantitative measurements of the flow in a simplified model ring chamber of the type used in axial-flow turbomachinery (see Fig. 1) to distribute flow entering a machine radially to the blading. The observations reveal that above a critical Reynolds number the flow swirls circumferentially around the ring chamber. The device then performs much like a vortex valve, a strong vortex being created in the exit tube beyond the center body. It is shown that the pressure loss in this case can be calculated fairly well using an analysis similar to that of Binnie and Hookings [1]. The exit-tube vortex is also responsible for the occurrence of a piercing whistling sound the frequency of which can be estimated using Vonnegut’s [2] theory for the vortex whistle. Observations are also presented for the symmetric flow situation which occurs at subcritical Reynolds numbers and for the case where swirl in the ring chamber is prevented by a baffle.
REVIEW—Unsteady Boundary Layers, Separated and Attached
Authors: Telionis D. P.
Published: October 2010

Unsteady boundary layers are investigated very actively today as a part of the effort to fully understand and calculate unsteady flows and their applications. As a result a number of review articles have appeared recently. The present review is a supplement to earlier contributions. Emphasis is given here to areas in which considerable progress has been achieved recently. However, in most of the interesting areas today, as for example in experimental investigation of unsteady turbulent boundary layers, modeling of unsteady separation and separated flows, no particular program has been completed. This review article, therefore, is a kind of a unified progress report which will hopefully capture the spirit of the work in progress in different countries of the western world and will identify potential difficulties and future needs.
Pressure Pulse Propagation in Two-Component Slug Flow
Authors: Martin C. Samuel , Padmanabhan M.
Published: October 2010

The simple model of pressure pulse propagation in slug flow proposed by Henry, Grolmes, and Fauske has been extended by considering wave reflection and wave transmission at gas-liquid interfaces. A frequency-response model applied to a series of idealized gas and liquid slugs yields a pulse propagation speed that approaches the homogeneous model value as the number of slugs is increased for a given void fraction. All characteristic roots from the solution to a three-equation drift-flux model are related to the velocity of the center of mass of the mixture. The pulse propagation speed relative to this velocity is exactly equal to the homogeneous model value, however. Measured pulse propagation speeds in vertically downward slug flow are, as anticipated, much less than those predicted by the simple model of Henry, Grolmes, and Fauske, but slightly greater than the homogeneous model value. Measured pressure surges produced by the rapid closure of a downstream valve in a pipeline are reasonably well predicted by the drift-flux model. For the range of void fractions, pressures, and velocities encountered in this study, it is concluded that pressure pulse speeds and the magnitude of pressure surges in slug flow can be adequately predicted by a homogeneous model.
Velocity Exponent for Erosion and Noise Due to Cavitation
Authors: Ramamurthy A. S. , Bhaskaran P.
Published: October 2010

The aim of the present study was to evaluate the effects of flow velocity on erosion and noise due to cavitation. To this end, tests were conducted in a two-dimensional water tunnel in which soft aluminum test specimens were mounted in the wake of a cavitating prismatic source. The prismatic source shape eliminated the Reynolds number effects on the flow characteristics. An excellent correlation appeared to be present between the erosion and noise due to cavitation in the range of velocities tested. At peak erosion conditions, the velocity exponents for erosion and intensity of noise were found to have an approximate value of 5.45. All the present tests were limited to a single cavitating source size for which the blockage ratio was fixed.
Isothermal, Compressible-Gas Flow in Horizontal Pipes With an Imperfect Gas
Authors: Madsen N. , Ramamoorthy P.
Published: October 2010

A method for calculating pressure drop, based on a three parameter “law” of corresponding states, is developed rigorously from thermodynamic and fluid dynamic principles. A pressure correction factor Y = 0.6527 + 0.3473Z is adequate for most practical problems, when the pressure is low and the compressibility factor, Z, is a linear function of the pressure. This result is checked against computations from natural-gas engineering, where the correction is not negligible. However, the method is applicable, by means of machine calculations, to problems where Z is not a linear function of pressure.
A Reynolds Stress Model for Flows With Drag Reduction
Authors: Hassid S.
Published: October 2010

A simple turbulence model has been proposed, which is based on the Reynolds stress equation and on the turbulence energy dissipation equation. By increasing the viscosity in the equations for the components of Reynolds stress in which the cross-stream velocity appears, the model is shown to be able to reproduce the main features of turbulent flows near walls when drag reducing polymers are present, namely: the changes in the velocity distribution, the increase in the streamwise and transverse fluctuating velocity components in the buffer zone, the decrease of the cross-stream component, and the spectacular increase in the length scale of near-wall turbulence. All the predictions of the model are in fair agreement with existing experimental data.
Vortex Motions Induced by V-Grooved Rotating Cylinders and Their Effect on Mixing Performance
Authors: Rotz C. A. , Suh N. P.
Published: October 2010

A numerical study of the fluid flows generated in the annular space between a rotating V-grooved cylinder and a hollow cylindrical shell is presented. The numerical procedures used to obtain flow solutions for different groove geometries at several Reynolds numbers, and the prediction of mixing performance of the various cores based on the analysis are discussed. The mixing quality is equated with the average equivalent strain a fluid element experiences as it flows through the annular space. The results of these computations are in good qualitative agreement with experimental results.
Turbulent Flow Measurements by Laser-Doppler Anemometry in Motored Piston-Cylinder Assemblies
Authors: Morse A. P. , Whitelaw J. H. , Yianneskis M.
Published: October 2010

Laser-Doppler anemometry has been used to quantify the mean velocity and turbulence characteristics of the isothermal, incompressible flow within a piston-cylinder arrangement motored without compression at 200 rpm and with idealized inlet geometries corresponding to a pipe and to an annular port located in the centre of the cylinder head. The results indicate that the pipe entry gives rise to a strong vortex near the piston as the indrawn air is deflected radially along the piston face and cylinder wall; this, in turn, gives rise to a weaker, counter-rotating vortex near the cylinder head which grows appreciably as the piston approaches bottom-dead-centre. With the annular-port entry, the inlet jet is angled and results in a flow pattern with a large vortex occupying nearly all of the flow space with much smaller vortices at the corners between the wall and the piston and cylinder heads. The effect of a piston bowl was also investigated for the port entry and is shown to be small.
Swirling Flow Through Annular Diffusers With Conical Walls
Authors: Lohmann R. P. , Markowski S. J. , Brookman E. T.
Published: October 2010

The performance of a series of diffusers of various lengths, area ratios and cant angles was determined experimentally over a range of inlet flow swirl angles between axial and 48 degrees. The results indicate that increases in the inlet swirl angle and the cant angle, particularly in combination, lead to increased distortion of the meridional velocity profile at the diffuser exit. With a swirling throughflow separation occurs at the inner wall and is encountered at progressively lower area ratios as the inlet swirl angle is increased. The tangential component of the flow is relatively independent of the meridional flow in that the angular momentum is essentially conserved and a high degree of similarity is found in these profiles at the diffuser exit.
Frictional Resistance of Enclosed Rotating Cones With Superposed Throughflow
Authors: Yamada Y. , Ito M.
Published: October 2010

The research summarized in this paper is an experimental study of the frictional moment on a cone rotating in a conical casing with an outward throughflow. The cone vertex angles tested in the present experiment are θ = 30, 60 and 90 deg. In the region where the frictional moment on the rotating cone with no throughflow is increased by the effect of Taylor-type vortices, an increase of the throughflow rate results in a decrease of the frictional moment, if the throughflow rate is not so large. In the region where the Taylor-type vortices have no appreciable effect on the frictional moment, on the other hand, the rate of increase in CM with increasing Cq. sin (θ/2) is almost independent of θ, where CM and Cq denote the moment coefficient and the dimensionless throughflow rate, respectively.
Torque Characteristics for Spherical Annulus Flow
Authors: Waked A. M. , Munson B. R.
Published: October 2010

The torque needed to rotate concentric spheres when the spherical annulus gap between them is filled with a viscous fluid depends on the Reynolds number and the ratio of the angular velocities of the two spheres. Experimental torque results for low to moderate Reynolds numbers are presented. The secondary flow effect is evident.
Effect of Nozzle Shape and Polymer Additives on Water Jet Appearance
Authors: Hoyt J. W. , Taylor J. J.
Published: October 2010

The effects of shape parameters on the performance of water-jet nozzles discharging in air were investigated using a camera specially adapted for jet photography. The boundary-layer developing on the exit surface of the nozzle is shown to account for the jet appearance revealed by high speed photography. Optimum nozzles seem to have the boundary-layer transition to turbulence inside the nozzle; transition outside the nozzle being accompanied by spray formation and early jet disruption. The effect of polymer additives seems to be earlier transition and a thinner turbulent boundary layer inside the nozzle which improves jet performance.
Numerical Simulation of Particulate Motion in Turbulent Gas-Solid Channel Flow
Authors: Peskin R. L. , Kau C. J.
Published: October 2010

A three-dimensional numerical model for turbulent shear flow in a channel with large Reynolds number is employed for the investigation of turbulent diffusion of finite inertia particulates. A stochastic nonlinear equation describing the motion of particles is integrated to obtain Lagrangian information. Special attention is paid to the effects of shear flow and wall boundary conditions. The results of these studies are compared to previous theoretical and empirical results. A cubic time dependency for separation is found at intermediate values of time while linear dependency is observed at large times. Schmidt numbers are always found to be smaller than one in the non-homogeneous region. It was concluded that special attention must be paid to appropriate computation times necessary to obtain a statistical equilibrium.
Stability of Flow From a Nuclear Cavity
Authors: Laude J. M. , Morrison F. A.
Published: October 2010

The stability of multicomponent flow through porous media is investigated. The flow results from an underground nuclear explosion. The effects of condensation, gravity, fluid mobilities, and heat transfer are considered. Marginal stability conditions and an expression for the decay rate of instabilities are obtained.
Turbulent Flow Over a Plane Symmetric Sudden Expansion
Authors: Smyth R.
Published: October 2010

Turbulent flow with separation and recirculation over a double backward facing step has been investigated experimentally. Time mean stream wise, transverse and cross-stream components of the velocity fluctuations, together with turbulence kinetic energy and Reynolds shear stresses, were measured using a laser Doppler anemometer, operating in the differential Doppler mode with forward scattering. Ordinary tap water was used in a closed loop flow system with a Reynolds number of 30,210 and significant changes of flow patterns, increases in turbulence kinetic energy, velocity fluctuations and shear stresses were observed downstream of the step expansion.
Predicted Secondary Flows in Triangular Array Rod Bundles
Authors: Trupp A. C. , Aly A. M. M.
Published: October 2010

A one-equation turbulence model was applied to forecast the main features of fully-developed turbulent flow through infinite equilateral triangular arrays of parallel rods having pitch-to-diameter ratios of 1.12 – 1.35 and Reynolds numbers of (2.7 – 25) × 104. For all cases, the secondary flow was found to be a single cell of circulation for each primary flow cell of a subchannel. The strength of the secondary flow increased with Reynolds number but decreased with rod spacing. The numerical results (which included friction factors, wall shear stress variations and axial velocity distributions) are shown to be in reasonable agreement with published experimental data.
A Wall-Flow-Direction Probe for Use in Separating and Reattaching Flows
Authors: Eaton J. K. , Jeans A. H. , Ashjaee J. , Johnston J. P.
Published: October 2010

The measurement of the exceedingly unsteady behavior of nominally two-dimensional, turbulent flows in regions of separation and reattachment is facilitated by the development of a new instrument; the wall-flow-direction probe which determines the instantaneous flow direction (upstream or downstream) in a thin layer of fluid very close to the wall. The probe was tested in low-speed, unsteady, separating and reattaching air flows. It appears to offer considerably more accuracy than other methods for the determination of time mean separation and reattachment points. In addition, the probe and its control circuits are relatively inexpensive and easy to construct.
A Calculation Procedure for Three-Dimensional, Viscous, Compressible Duct Flow. Part I—Inviscid Flow Considerations
Authors: Moore John , Moore Joan G.
Published: October 2010

A method for computing three-dimensional duct flows is described. The procedure involves iteration between a marching integration of the conservation equations through the flow field and the solution of an elliptic pressure-correction equation. The conservation equations are written in orthogonal curvilinear coordinates. The solution procedure is illustrated by calculations of two-dimensional flow in an accelerating rectangular elbow with 90 deg of turning. An approach to calculating three-dimensional viscous flow, starting with the solution for two-dimensional inviscid flow is suggested. This approach is used in Part II which starts with the results of the present two-dimensional “inviscid” flow calculations.
Griffith Diffusers
Authors: Yang Tah-teh , Nelson C. D.
Published: October 2010

Contoured wall diffusers are designed by using an inverse method. The prescribed wall velocity distribution(s) was taken from the high lift airfoil designed by A. A. Griffith in 1938; therefore, such diffusers are named Griffith diffusers. First the formulation of the inverse problem and the method of solution are outlined. Then the typical contour of a two-dimensional diffuser and velocity distributions across the flow channel at various stations are presented. For a Griffith diffuser to operate as it is designed, boundary layer suction is necessary. Discussion of the percentage of through-flow required to be removed for the purpose of boundary layer control is given. The typical performance is presented for a Griffith diffuser having the ratio (Cpmeasured / Cpideal) = 98 percent and at the exit plane the ratio of (Ulocal − Uavg.) / Uavg. = ± 5 percent. Finally, reference is made to the latest version of a computer program for a two-dimensional diffuser requiring only area ratio, nondimensional length and suction percentage as inputs.
The Stolz and ASME-AGA Orifice Equations Compared to Laboratory Data
Authors: Miller R. W.
Published: October 2010

Today, technical experts in Europe and the U.S. are debating the merits of conducting new orifice flowmeter tests, establishing the effects of upstream disturbance and conducting other programs to improve orifice flowmetering accuracy. ISO has adopted a new “Universal” orifice equation proposed by J. Stolz. With over 1,000,000 orifice flowmeters in use today, any change in the coefficient value is of major concern. There are now two equations for calculating flange tap coefficients, the ASME-AGA equation and the ISO equation. They differ in form, predict different coefficients, and have different overall uncertainties (tolerance value). This paper presents a comparison between actual laboratory data and these two equations. The data were obtained in two high accuracy laboratories on flange tap orifice flowmeters fabricated by different manufacturers to AGA or ASME recommendations. Data plate dimensions were used in all calculations, and conformity to ASME or AGA requirements was the responsibility of the manufacturer. For this reason it is believed that the analysis more nearly represents what the user can expect if the in-site installation approached that of the laboratory. Results indicate that over the same beta ratio range the ISO (or Stolz) equation form is significantly better than the present ASME-AGA form. The overall uncertainty (or tolerance), although smaller than the ASME-AGA, is still ± 1 percent because of a 0.4 percent systematic error. Results of work by Miller-Kneisel, using data from three different laboratories, are presented to indicate that ±0.5 percent remains achievable; for betas up to 0.7 using the ISO (Stolz) equation form with modified coefficients.
An Investigation of Pressure Transients in Viscoelastic Pipes
Authors: Gally M. , Gu¨ney M. , Rieutord E.
Published: October 2010

Calculated results based on a theoretical analysis of hydraulic transients in pipes taking into account the viscoelastic behavior of pipewall material are compared with experimental results. This comparison shows that the model accurately predicts pressure fluctuations in fluid and circumferential strain changes of the pipe during transients resulting from the rapid closure of a valve.
A Comparison of Correction Methods Used in the Evaluation of Drag Coefficient Measurements for Two-Dimensional Rectangular Cylinders
Authors: Courchesne J. , Laneville A.
Published: October 2010

This paper describes an experimental evaluation of available drag correction formulae and theories for blockage effects applicable to two-dimensional rectangular cylinders immersed in a low-turbulence uniform flow. It is observed that empirical formulae are functions of the afterbody length and that Maskell’s theory has the tendency to overestimate the correction.
Geometric Optimization of Concentrating Solar Collectors using Monte Carlo Simulation
Authors: Marston A. J. , Daun K. J. , Collins M. R.
Published: October 2010

This paper presents an optimization algorithm for designing linear concentrating solar collectors using stochastic programming. A Monte Carlo technique is used to quantify the performance of the collector design in terms of an objective function, which is then minimized using a modified Kiefer–Wolfowitz algorithm that uses sample size and step size controls. This process is more efficient than traditional “trial-and-error” methods and can be applied more generally than techniques based on geometric optics. The method is validated through application to the design of three different configurations of linear concentrating collector.