bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency of t(14;18) in follicular lymphoma patients: geographical or technical variation
Authors: ISMAIL S. I. , SUGHAYER M. A. , AL‐QUADAN T. F. , QAQISH B. M. , TARAWNEH M. S.
Published: May 2008

The t(14;18) translocation is the most distinguishing molecular finding in follicular lymphoma (FL). However, the reported frequencies of t(14;18) in FL show significant variation, which is often attributed to geographical and/or methodological factors. The methods used to detect t(14;18) include Southern blotting, conventional cytogenetics, fluorescent in situ hybridization, and polymerized chain reaction (PCR). Because of its practicality and superior sensitivity, PCR is becoming the more commonly used method in clinical laboratories. The identification of the main breakpoint regions on chromosome 18, including the major breakpoint region (MBR), the minor cluster region (mcr), and the newly defined intermediate cluster region (icr), increased the detection frequency of PCR. In our study, using a highly sensitive nested PCR strategy with primers for MBR, mcr and icr regions, we were able to detect t(14;18) in 95% of FL patients, which is one of the highest reported frequencies using PCR. We screened 58 FL patient samples collected retrospectively from different hospitals in Jordan. DNA was extracted from archival paraffin‐embedded samples, some of which were >10 years old. The respective breakpoint distributions were, 47 for MBR (81%), two for mcr (3.5%) and six for icr (10.3%). In this report, we analyze this high frequency of t(14;18) detection in a general review of the recent literature, in an attempt to assess the geographical vs. methodological influences on the reported frequencies.
Coding Sequence Mutations Identified in MYH7, TNNT2, SCN5A, CSRP3, LBD3, and TCAP from 313 Patients with Familial or Idiopathic Dilated Cardiomyopathy
Authors: Hershberger Ray E. , Parks Sharie B. , Kushner Jessica D. , Li Duanxiang , Ludwigsen Susan , Jakobs Petra , Nauman Deirdre , Burgess Donna , Partain Julie , Litt Michael
Published: May 2008

Background: More than 20 genes have been reported to cause idiopathic and familial dilated cardiomyopathy (IDC/FDC), but the frequency of genetic causation remains poorly understood.

Methods and Results: Blood samples were collected and DNA prepared from 313 patients, 183 with FDC and 130 with IDC. Genomic DNA underwent bidirectional sequencing of six genes, and mutation carriers were followed up by evaluation of additional family members. We identified in 36 probands, 31 unique protein‐altering variants (11.5% overall) that were not identified in 253 control subjects (506 chromosomes). These included 13 probands (4.2%) with 12 β‐myosin heavy chain (MYH7) mutations, nine probands (2.9%) with six different cardiac troponin T (TNNT2) mutations, eight probands (2.6%) carrying seven different cardiac sodium channel (SCN5A) mutations, three probands (1.0%) with three titin‐cap or telethonin (TCAP) mutations, three probands (1.0%) with two LIM domain binding 3 (LDB3) mutations, and one proband (0.3%) with a muscle LIM protein (CSRP3) mutation. Four nucleotide changes did not segregate with phentoype and/or did not alter a conserved amino acid and were therefore considered unlikely to be disease‐causing. Mutations in 11 probands were assessed as likely disease‐causing, and in 21 probands were considered possibly disease‐causing. These 32 probands included 14 of the 130 with IDC (10.8%) and 18 of the 183 with FDC (9.8%)

Conclusions: Mutations of these six genes each account for a small fraction of the genetic cause of FDC/IDC. The frequency of possible or likely disease‐causing mutations in these genes is similar for IDC and FDC.
Use of Salsalate to Target Inflammation in the Treatment of Insulin Resistance and Type 2 Diabetes
Authors: Goldfine Allison B. , Silver Robert , Aldhahi Waleed , Cai Dongsheng , Tatro Elizabeth , Lee Jongsoon , Shoelson Steven E.
Published: May 2008

Objectives: Chronic subacute inflammation is implicated in the pathogenesis of insulin resistance and type 2 diabetes. Salicylates were shown years ago to lower glucose and more recently to inhibit NF‐κB activity. Salsalate, a prodrug form of salicylate, has seen extensive clinical use and has a favorable safety profile. We studied the efficacy of salsalate in reducing glycemia and insulin resistance and potential mechanisms of action to validate NF‐κB as a potential pharmacologic target in diabetes.

Methods and Results: In open label studies, both high (4.5 g/d) and standard (3.0 g/d) doses of salsalate reduced fasting and postchallenge glucose levels after 2 weeks of treatment. Salsalate increased glucose utilization during euglycemic hyperinsulinemic clamps, by approximately 50% and 15% at the high and standard doses, respectively, and insulin clearance was decreased. Dose‐limiting tinnitus occurred only at the higher dose. In a third, double‐masked, placebo‐controlled trial, 1 month of salsalate at maximum tolerable dose (no tinnitus) improved fasting and postchallenge glucose levels. Circulating free fatty acids were reduced and adiponectin increased in all treated subjects.

Conclusions: These data demonstrate that salsalate improves in vivo glucose and lipid homeostasis, and support targeting of inflammation and NF‐κB as a therapeutic approach in type 2 diabetes.
Archives of Drug Information—A New Approach to Publishing the Results of Drug Studies
Authors: Stein C. Michael
Published: May 2008

Current scientific publishing uses a selective, slow, and adversarial editorial process to publish a minority of papers submitted, and thus maximize a journal's impact factor, a major measure of success. However, the results of many pharmaceutical industry studies are deemed low priority and are therefore difficult or impossible to publish in scientific journals. Society is poorly served because access to the results of these studies is in the public interest. Archives of Drug Information is an independent, online only journal that will publish papers that are free of bias and that provide new information about a drug. Articles that would not usually be published by traditional journals, for example articles reporting negative studies, studies reporting animal toxicity or Phase I human studies, or routine pharmacokinetic or drug interaction studies are welcome. The editorial process will be rapid and user friendly. The contents of the journal will be available freely to all. Archives of Drug Information will allow the pharmaceutical industry to publish the results of studies and make freely accessible to the public the results of research studies that would otherwise remain unavailable “on‐file.” Making the results of studies available to the public is not only ethical and good scientific citizenship, but ultimately, also good business.
A Comparison of Cardiovascular Biomarkers in Patients Treated for Three Months with Etoricoxib, Celecoxib, Ibuprofen, and Placebo
Authors: Cannon Christopher P. , Chen Cong , Curtis Sean P. , Viscusi John , Ahmed Tuli , DiBattiste Peter M.
Published: May 2008

Objectives.  Selective cyclooxygenase (COX)‐2 inhibitors are effective analgesic and anti‐inflammatory agents with improved gastrointestinal safety and tolerability compared with traditional NSAIDs. However, data from long‐term, placebo‐controlled studies have shown an increased risk of thrombotic cardiovascular (CV) events for COX‐2 inhibitors. Changes in levels of CV biomarkers are potentially useful surrogate measures of pathologic changes associated with CV risk.

Methods.  We randomized 433 patients with osteoarthritis to etoricoxib 90 mg once daily, celecoxib 200 mg twice daily, ibuprofen 800 mg three times daily, or placebo for 12 weeks. The hypothesis was that etoricoxib would be non‐inferior or superior to placebo in effect on C‐reactive protein (CRP), LDL‐cholesterol, homocysteine, and fibrinogen.

Results.  Relative to placebo, etoricoxib was noninferior for effect on CRP (decreased 7.8% vs. placebo; 97.5% CI of the difference: −30.5, 22.4), LDL‐C (−4.0% vs. placebo; 97.5% CI: −10.6, 3.2), homocysteine (−3.9% vs. placebo; 97.5% CI: −11.6, 4.6), and fibrinogen (−3.7% vs. placebo; 97.5% CI: −9.4, 2.3). Etoricoxib was not different from placebo, celecoxib, or ibuprofen for any biomarker.

Conclusion.  Etoricoxib was comparable to placebo, celecoxib, and ibuprofen for effects on the CV risk markers measured.
Effects of C‐reactive Protein and Homocysteine on Cytokine Production: Modulation by Pravastatin
Authors: Asanuma Yu , Oeser Annette , Stanley Eran , Bailey David G. , Shintani Ayumi , Stein C. Michael
Published: May 2008

Objective.  C‐reactive protein (CRP) and homocysteine are markers of cardiovascular risk that may have inflammatory effects. HMG coenzyme A reductase inhibitors (statins) have anti‐inflammatory effects in vitro, but it is not clear if such responses in vivo are secondary to lipid lowering. We examined the hypothesis that CRP and homocysteine would stimulate cytokine release in human whole blood and that short‐term treatment with a statin would inhibit it.

Methods.  The time course of IL‐6 and MCP‐1 production was determined in whole blood incubated with saline, 1 µg/mL lipopolysaccaride (LPS), 50 and 100 µM/L DL‐homocysteine, and 5 µg/mL human recombinant CRP for 24 hours at 37°C under 5% CO2 atmosphere. Cytokine responses were determined in blood drawn from 15 healthy volunteers before and after administration of pravastatin 40 mg daily for 2 days.

Results.  Both human recombinant CRP and LPS significantly increased the production of IL‐6 and MCP‐1 in whole blood samples more than 4‐fold (P < 0.001) but homocysteine did not. Oral administration of pravastatin, 40mg daily for 2 days, decreased CRP‐stimulated IL‐6 production by approximately 20% (P = 0.02) 6 hours after incubation, but did not affect MCP‐1 production (P = 0.69). Pravastatin treatment did not affect LPS‐stimulated MCP‐1 but increased IL‐6 modestly.

Conclusions.  CRP stimulated the production of the proatherogenic mediators MCP‐1 and IL‐6 in human whole blood, but homocysteine did not. CRP‐stimulated production of IL‐6, but not MCP‐1, was modestly attenuated by short‐term treatment with pravastatin.
Drugs to Treat Systemic Lupus Erythematosus: Relationship between Current Use and Cardiovascular Risk Factors
Authors: Rho Young Hee , Oeser Annette , Chung Cecilia P. , Morrow Jason D. , Stein C. Michael
Published: May 2008

Objectives.  Cardiovascular risk is increased in patients with systemic lupus erythematosus (SLE). Drugs used to treat SLE can modify traditional cardiovascular risk factors. We examined the effect of selected drugs used in the treatment of SLE on cardiovascular risk factors.

Methods.  We compared systolic and diastolic blood pressure, serum lipid concentrations, glucose, homocysteine, and urinary F2‐isoprostane concentrations in 99 patients with lupus who were either current users or non‐users of systemic corticosteroids, antimalarials, non‐steroidal anti‐inflammatory drugs (NSAIDs), COX‐2 selective NSAIDs, azathioprine, and methotrexate. Multivariable adjustment was done with linear regression modeling using sex, age and disease activity (SLEDAI) as controlling variables.

Results.  Serum triglyceride concentrations were higher (135.1 ± 61.4 vs. 95.3 ± 47.5 mg/dL, adjusted P = 0.003) in patients receiving corticosteroids. Homocysteine concentrations were marginally higher in patients receiving methotrexate (adjusted P = 0.08). Current use of either NSAIDs or COX‐2 inhibitors was not associated with increased cardiovascular risk factors. Current hydroxychloroquine use was not associated with significant alterations in lipid profiles.

Conclusions.  In a non‐random sample of patients with SLE, current corticosteroid use was associated with increased triglyceride concentrations, but other drugs had little effect on traditional cardiovascular risk factors.
Stem cells and periodontal regeneration
Authors: Lin N‐H , Gronthos S , Bartold PM
Published: May 2008

Periodontitis is an inflammatory disease which manifests clinically as loss of supporting periodontal tissues including periodontal ligament and alveolar bone. For decades periodontists have sought ways to repair the damage which occurs during periodontitis. This has included the use of a range of surgical procedures, the use of a variety of grafting materials and growth factors, and the use of barrier membranes. To date periodontal regeneration is considered to be biologically possible but clinically unpredictable. Recently, reports have begun to emerge demonstrating that populations of adult stem cells reside in the periodontal ligament of humans and other animals. This opens the way for new cell‐based therapies for periodontal regeneration. For this to become a reality a thorough understanding of adult human stem cells is needed. This review provides an overview of adult human stem cells and their potential use in periodontal regeneration.
Participation in continuing professional development by Victorian dental practitioners in 2004
Authors: Hopcraft MS , Marks G , Manton DJ
Published: May 2008

Background:  Continuing professional development (CPD) has been long considered an integral component of professional practice across a range of health professions. It is believed to ensure the maintenance of practitioner clinical competence and knowledge of current concepts. This study investigated the participation in and attitudes of Victorian dental personnel to CPD activities.

Methods:  A self‐administered cross‐sectional survey of a random sample of registered dental care providers (n = 451) was conducted from March to June 2005 using an anonymous, postal, self‐administered questionnaire.

Results:  The response rate was low (48.1 per cent). Nearly 90 per cent of respondents attended a CPD course in 2004, with the mean hours of attendance ranging from 8.3 to 36.9 hours, depending on registration category. Nearly half of the dentists attended more than 20 hours of CPD courses, while less than 20 per cent of prosthetists attended more than 15 hours of CPD courses. Three‐quarters of respondents supported mandatory CPD as a condition of registration.

Conclusions:  There was a high level of participation in continuing professional development activities by surveyed Victorian dental care providers in 2004, although more than half of the dentists and specialists, and nearly two‐thirds of therapists, hygienists and prosthetists would fail to meet the new DPBV mandatory requirements for CPD.
Bond strength test: role of operator skill
Authors: Adebayo OA , Burrow MF , Tyas MJ
Published: May 2008

Background:  Test method, substrate material and operator variability are factors known to affect bond strength test outcomes. The aim of this study was to determine if, with increasing experience, individual operator skill in material handling influenced microshear bond strength outcomes.

Methods:  This retrospective study used data collected from six preliminary tests carried out successively on enamel microshear bond strength for two adhesives: Clearfil SE Bond (Kuraray) and Adper Single Bond 2 (3M ESPE) by one operator. Mean and median microshear bond strength values, standard deviations and coefficients of variation for each adhesive test group were calculated and assessed.

Results:  A gradual increase in mean microshear bond strengths, a decrease in standard deviations and coefficients of variation over time for both adhesives and a progressively more uniform distribution of microshear bond strength results recorded in individual test sets was observed. The results suggest an improvement in bonding reliability as experience is gained.

Conclusions:  Operator skill in material handling appears to play a critical role in determining the outcome of bond strength testing. This same skill is probably relevant when using an adhesive for the first time clinically. It is important that clinicians become familiar with new adhesives in order to achieve optimal outcomes.
Quarter of a century of change: caries experience in Australian children, 1977–2002
Authors: Armfield JM , Spencer AJ
Published: May 2008

Background:  The establishment of the evaluation programme of the Australian School Dental Scheme has led to continuous surveillance of child oral health extending from 1977 to the present day. The aims of this study were to examine the state of child oral health in Australia in 2002 and to explore longer term trends across the quarter of a century of recorded surveillance activity.

Methods:  Caries data were obtained for children who were enrolled in the School Dental Services of each state and territory for the years 1977–2002. Data collection derived from routine examinations within the School Dental Service with oral examinations carried out by dentists and dental therapists.

Results:  There were considerable declines in caries experience between 1977 and the mid to late 1990s, with mean decayed, missing and filled deciduous teeth (dmft) for 6‐year‐old children decreasing from over 3 in 1977 to approximately 1.6 in 1996, and permanent 12‐year‐old decayed, missing and filled teeth (DMFT) decreasing from 4.8 in 1977 to 0.89 in 1998. However, since the mid to late 1990s, deciduous 6‐year‐old dmft has increased by 24 per cent and 12‐year‐old DMFT has increased by almost 15 per cent. Reductions in caries experience of those children with the most disease have also ceased, and between 1999 and 2002 an increase in the Significant Caries Index occurred.

Conclusions:  Improvements in the oral health of Australian children halted during the mid 1990s, after which caries experience has increased. It is important that we understand the changes taking place and their causes, so that action can be taken to halt any further possible declines in child oral health.
Relationship between quantitative assessments of salivary buffering capacity and ion activity product for hydroxyapatite in relation to cariogenic potential
Authors: Aiuchi H , Kitasako Y , Fukuda Y , Nakashima S , Burrow MF , Tagami J
Published: May 2008

Background:  The ion activity product for hydroxyapatite (IpHA) is a comprehensive parameter reflecting pH, calcium and phosphate ion concentration in saliva which govern the degree of saturation with respect to the dissolving tooth mineral. The aim of this study was to evaluate the relationship between quantitative assessments of salivary buffering capacity and IpHA in relation to cariogenic potential.

Methods:  Stimulated whole saliva was collected from 33 patients, and the initial pH of samples was measured using a hand‐held pH meter. Then samples were titrated with 0.1 N HCl to evaluate buffering capacities and divided into three groups (high, medium and low). After measuring concentrations of calcium and phosphate ions in the samples, IpHA was calculated using the values of the ion concentrations and pH. Differences in the mean pH values, the concentrations of calcium, phosphate ions and log[IpHA] among three groups were analysed using the Kruskal Wallis and the Mann‐Whitney non‐parametric test, p < 0.05.

Results:  After HCl 50 μL titration, there were statistical differences of the mean pH and IpHA among each buffering capacity group. Moreover, after 50 μL HCl titration, there was an excellent correlation between the buffer capacity and log[IpHA].

Conclusions:  The pH change for saliva after HCl titration has a significant influence on the rate of IpHA.
Oral impact of gastro‐oesophageal reflux disease: a case report
Authors: Liberali SAC
Published: May 2008

Background:  This case report describes the dental management of a 30‐year‐old male with cerebral palsy and dyspraxia. Recall examination identified multiple erosive carious lesions despite previous oral hygiene and dietary related instruction. A comprehensive approach to patient management was required to identify the aetiological factors associated with the continued loss of tooth structure.

Methods:  The identification of the aetiological factors required a detailed medical history and clinical examination, as well as liaison with the patient’s general medical practitioner. Preventive measures were adopted prior to restorative intervention in order to stabilize and remineralize the dentition.

Results:  Medical intervention for gastro‐oesophageal reflux disease (GORD) and a targeted prevention programme resulted in remineralization of all carious exposed dentine with stabilization of the dentition.

Conclusions:  Patients with cerebral palsy are known to have a higher incidence of GORD as well as problems with swallowing, vomiting and recurrent chest infections. Long‐term gastric acid attacks can contribute to dental erosion, and dental professionals may be the first to diagnose silent GORD. The successful treatment of erosion caused by GORD requires a multidisciplinary and minimal intervention approach.
The Bochner-flat cone of a CR manifold
Authors: David Liana
Published: May 2008

We construct a Kähler structure (which we call a generalised Kähler cone) on an open subset of the cone of a strongly pseudo-convex CR manifold endowed with a one-parameter family of compatible Sasaki structures. We determine those generalised Kähler cones which are Bochner-flat and we study their local geometry. We prove that any Bochner-flat Kähler manifold of complex dimension bigger than two is locally isomorphic to a generalised Kähler cone.
A generalized Gaeta’s theorem
Authors: Gorla Elisa
Published: May 2008

We generalize Gaeta’s theorem to the family of determinantal schemes. In other words, we show that the schemes defined by minors of a fixed size of a matrix with polynomial entries belong to the same G-biliaison class of a complete intersection whenever they have maximal possible codimension, given the size of the matrix and of the minors that define them.
Hypertranscendance des systèmes aux différences diagonaux
Authors: Hardouin Charlotte
Published: May 2008

This paper deals with criteria of algebraic independence for the derivatives of solutions of diagonal difference systems. The key idea consists in deriving from the commutativity of the differentiation and difference operators a sequence of iterated extensions of the original difference module, thereby setting the problem in the framework of difference Galois theory and finally reducing it to an exercise in linear algebra on the group of divisors of the involved elliptic curve or torus.
Snapping of a Planar Elastica With Fixed End Slopes
Authors: Chen Jen-San , Lin Yong-Zhi
Published: May 2008

In this paper, we study the deformation and stability of a planar elastica. One end of the elastica is clamped and fixed in space. The other end of the elastica is also clamped, but the clamp itself is allowed to slide along a linear track with a slope different from that of the fixed clamp. The elastica deforms after it is subjected to an external pushing force on the moving clamp. It is observed that when the pushing force reaches a critical value, snapping may occur as the elastica jumps from one configuration to another remotely away from the original one. In the theoretical investigation, we calculate the static load-deflection curve for a specified slope difference between the fixed clamp and the moving clamp. To study the stability of the equilibrium configuration, we superpose the equilibrium configuration with a small perturbation and calculate the natural frequencies of the deformed elastica. An experimental setup is designed to measure the load-deflection curve and the natural frequencies of the elastica. The measured load-deflection relation agrees with the theoretical prediction very well. On the other hand, the measured natural frequencies do not agree very well with the theoretical prediction, unless the mass of the moving clamp is taken into account.
A Micromechanics Model for the Thermal Conductivity of Nanotube-Polymer Nanocomposites
Authors: Seidel Gary D. , Lagoudas Dimitris C.
Published: May 2008

A micromechanics approach for assessing the impact of an interfacial thermal resistance, also known as the Kapitza resistance, on the effective thermal conductivity of carbon nanotube-polymer nanocomposites is applied, which includes both the effects of the presence of the hollow region of the carbon nanotube (CNT) and the effects of the interactions amongst the various orientations of CNTs in a random distribution. The interfacial thermal resistance is a nanoscale effect introduced in the form of an interphase layer between the CNT and the polymer matrix in a nanoscale composite cylinder representative volume element to account for the thermal resistance in the radial direction along the length of the nanotube. The end effects of the interfacial thermal resistance are accounted for in a similar manner through the use of an interphase layer between the polymer and the CNT ends. Resulting micromechanics predictions for the effective thermal conductivity of polymer nanocomposites with randomly oriented CNTs, which incorporate input from molecular dynamics for the interfacial thermal resistance, demonstrate the importance of including the hollow region in addition to the interfacial thermal resistance, and compare well with experimental data.
Application of Electrohydrodynamic Atomization to Two-Phase Impingement Heat Transfer
Authors: Feng Xin , Bryan James E.
Published: May 2008

The effect of electric fields applied to two-phase impingement heat transfer is explored for the first time. The electric field applied between a capillary tube and heated surface enhances the heat transfer by controlling the free boundary flow modes from discreet drops to jets, to sprays. Through an experimental study, the impingement heat transfer was evaluated over a range of operating conditions and geometrical parameters with subcooled ethanol used as the working fluid. The ability to change the mode of impinging mass did change the surface heat transfer. The characteristics of the impinging mass on heat transfer were dependent on flow rate, applied voltage, capillary tube to heated surface spacing, capillary tube geometry, heat flux, heater surface geometry, and capillary tube array configuration. Enhancement occurred primarily at low heat fluxes (below 30W∕cm2) under ramified spray conditions where the droplet momentum promoted thin films on the heated surface resulting in 1.7 times enhancement under certain conditions. Higher heat fluxes resulted in greater vapor momentum from the surface, minimizing the effect of different impingement modes. The use of capillary tube array allowed for electrohydrodynamics atomization enhancement and higher liquid flow rates, but electrostatic repulsive forces diverted the spray from the heater surface. This reduced the mass flux to the surface, leading to premature dryout under certain conditions.
Heat Transfer in Trailing Edge, Wedge-Shaped Cooling Channels Under High Rotation Numbers
Authors: Wright Lesley M. , Liu Yao-Hsien , Han Je-Chin , Chopra Sanjay
Published: May 2008

Heat transfer coefficients are experimentally measured in a rotating cooling channel used to model an internal cooling passage near the trailing edge of a gas turbine blade. The regionally averaged heat transfer coefficients are measured in a wedge-shaped cooling channel (Dh=2.22cm, Ac=7.62cm2). The Reynolds number of the coolant varies from 10,000 to 40,000. By varying the rotational speed of the channel, the rotation number and buoyancy parameter range from 0 to 1.0 and 0 to 3.5, respectively. Significant variation of the heat transfer coefficients in both the spanwise and streamwise directions is apparent. Spanwise variation is the result of the wedge-shaped design, and streamwise variation is the result of the sharp entrance into the channel and the 180deg turn at the outlet of the channel. With the channel rotating at 135° with respect to the direction of rotation, the heat transfer coefficients are enhanced on every surface of the channel. Both the nondimensional rotation number and buoyancy parameter have proven to be excellent parameters to quantify the effect of rotation over the extended ranges achieved in this study.
Film Cooling Effectiveness Distribution on a Gas Turbine Blade Platform With Inclined Slot Leakage and Discrete Film Hole Flows
Authors: Wright Lesley M. , Gao Zhihong , Yang Huitao , Han Je-Chin
Published: May 2008

A five-blade, linear cascade is used to experimentally investigate turbine blade platform cooling. A 30deg inclined slot upstream of the blades is used to model the seal between the stator and rotor, and 12 discrete film holes are located on the downstream half of the platform for additional cooling. The film cooling effectiveness is measured on the platform using pressure sensitive paint (PSP). Using PSP, it is clear that the film cooling effectiveness on the blade platform is strongly influenced by the platform secondary flow through the passage. Increasing the slot injection rate weakens the secondary flow and provides more uniform film coverage. Increasing the freestream turbulence level was shown to increase film cooling effectiveness on the endwall, as the increased turbulence also weakens the passage vortex. However, downstream, near the discrete film cooling holes, the increased turbulence decreases the film cooling effectiveness. Finally, combining upstream slot flow with downstream discrete film holes should be cautiously done to ensure coolant is not wasted by overcooling regions on the platform.
Instability
of Nanofluids in Natural Convection
Authors: Tzou D.
Y.
Published: May 2008

Instability of natural convection in nanofluids is investigated in this work. As a result of Brownian motion and thermophoresis of nanoparticles, the critical Rayleigh number is shown to be much lower, by one to two orders of magnitude, as compared to that for regular fluids. The highly promoted turbulence, in the presence of nanoparticles for as little as 1% in volume fraction, significantly enhances heat transfer in nanofluids, which may be much more pronounced than the enhancement of the effective thermal conductivity alone. Seven dominating groups are extracted from the nondimensional analysis. By extending the method of eigenfunction expansions in conjunction with the method of weighted residuals, closed-form solutions are derived for the Rayleigh number to justify such remarkable change by the nanoparticles at the onset of instability.
Laminar Filmwise Condensation on Horizontal Disk Embedded in Porous Medium With Suction at Wall
Authors: Chang Tong-Bou
Published: May 2008

This study performs a theoretical investigation into the problem of two-dimensional steady filmwise condensation flow on a horizontal disk embedded in a porous medium layer with suction at the disk surface. The analysis considers the case of a water-vapor system and is based on typical values of the relevant dimensional and dimensionless parameters. Due to the effects of capillary forces, a two-phase zone is formed between the liquid film and the vapor zone. The minimum mechanical energy concept is employed to establish the boundary condition at the edge of the horizontal disk and the Runge–Kutta shooting method is used to solve the second-order nonlinear ordinary differential equation of the liquid film. It is found that the capillary force and wall suction effects have a significant influence on the heat transfer performance. Specifically, the results show that the dimensionless heat transfer coefficient depend on the Darcy number Da, the Jacob number Ja, the effective Rayleigh number Rae, the effective Prandtl number Pre, the suction parameter Sw, and the capillary parameter Boc.
Critical Heat Flux of Water at Subatmospheric Pressures in Microchannels
Authors: Kuo C.-J. , Peles Y.
Published: May 2008

Critical heat flux conditions for water at subatmospheric pressures in an array of silicon-based, 227μm hydraulic diameter, rectangular microchannels were experimentally studied. Experiments were conducted at exit pressures from 0.1atmto1atm, mass fluxes from 86kg∕m2sto303kg∕m2s, and an effective heat flux up to 444W∕cm2. The annular flow pattern revealed during flow visualization and the high exit qualities at CHF conditions suggest dryout to be the CHF mechanism. An analysis, based on the experimental results and known CHF characteristics, on the dependency of the critical heat flux on various variables was performed. It was found that the boiling number at the CHF condition was approximately a constant.
Experimental and Analytical Studies of Reciprocating-Mechanism Driven Heat Loops (RMDHLs)
Authors: Cao Yiding , Gao Mingcong
Published: May 2008

This paper conducts experimental and analytical studies of a novel heat-transfer device, reciprocating-mechanism driven heat loop (RMDHL) that facilitates two-phase heat transfer while eliminating the so-called cavitation problem commonly encountered by a conventional pump. A RMDHL normally includes a hollow loop having an interior flow passage, an amount of working fluid filled within the loop, and a reciprocating driver. The hollow loop has an evaporator section, a condenser section, and a liquid reservoir. The reciprocating driver is integrated with the liquid reservoir and facilitates a reciprocating flow of the working fluid within the loop, so that liquid is supplied from the condenser section to the evaporator section under a substantially saturated condition and the so-called cavitation problem associated with a conventional pump is avoided. The reciprocating driver could be a solenoid-operated reciprocating driver for electronics cooling applications and a bellows-type reciprocating driver for high-temperature applications. Experimental study has been undertaken for a solenoid-operated heat loop in connection with high heat flux thermal management applications. Experimental results show that the heat loop worked very effectively and a heat flux as high as 300W∕cm2 in the evaporator section could be handled. A working criterion has also been derived, which could provide a guidance for the design of a RMDHL.
Stability and Vibration Behavior of Composite Cylindrical Shell Panels Under Axial Compression and Secondary Loads
Authors: Girish J. , Ramachandra L. S.
Published: May 2008

The nonlinear static response and vibration behavior of cross-ply laminated cylindrical shell panels subjected to axial compression combined with other secondary loading are examined. The shell theory adopted in the present case is based on a higher-order shallow shell theory, includes geometric imperfection and von Kármán-type geometric nonlinearity. The solutions to the governing nonlinear partial differential equations are sought using the multiterm Galerkin technique. The nonlinear equilibrium paths through limit points and bifurcation points are traced using the Newton–Raphson method coupled with the Riks approach. The free vibration frequencies of post-buckled cylindrical panels about the static equilibrium state are reported by solving the associated linear eigenvalue problem. Results are presented for simply supported cross-ply laminated cylindrical shell panels, which illustrates the influence of initial geometric imperfection, temperature field, lateral pressure loads, and mechanical edge loads on the static response and vibration behavior of the shell panel.
Parametric Instability of an Axially Moving Belt Subjected to Multifrequency Excitations: Experiments and Analytical Validation
Authors: Michon Guilhem , Manin Lionel , Remond Didier , Dufour Regis , Parker Robert G.
Published: May 2008

This paper experimentally investigates the parametric instability of an industrial axially moving belt subjected to multifrequency excitation. Based on the equations of motion, an analytical perturbation analysis is achieved to identify instabilities. The second part deals with an experimental setup that subjects a moving belt to multifrequency parametric excitation. A data acquisition technique using optical encoders and based on the angular sampling method is used with success for the first time on a nonsynchronous belt transmission. Transmission error between pulleys, pulley/belt slip, and tension fluctuation are deduced from pulley rotation angle measurements. Experimental results validate the theoretical analysis. Of particular note is that the instability regions are shifted to lower frequencies than the classical ones due to the multifrequency excitation. This experiment also demonstrates nonuniform belt characteristics (longitudinal stiffness and friction coefficient) along the belt length that are unexpected sources of excitation. These variations are shown to be sources of parametric instability.
Slow Steady Viscous Flow of Newtonian Fluids in Parallel-Disk Viscometer With Wall Slip
Authors: Yeow Y. Leong , Leong Yee-Kwong , Khan Ash
Published: May 2008

The parallel-disk viscometer is a widely used instrument for measuring the rheological properties of Newtonian and non-Newtonian fluids. The torque-rotational speed data from the viscometer are converted into viscosity and other rheological properties of the fluid under test. The classical no-slip boundary condition is usually assumed at the disk-fluid interface. This leads to a simple azimuthal flow in the disk gap with the azimuthal velocity linearly varying in the radial and normal directions of the disk surfaces. For some complex fluids, the no-slip boundary condition may not be valid. The present investigation considers the flow field when the fluid under test exhibits wall slip. The equation for slow steady azimuthal flow of Newtonian fluids in parallel-disk viscometer in the presence of wall slip is solved by the method of separation of variables. Both linear and nonlinear slip functions are considered. The solution takes the form of a Bessel series. It shows that, in general, as a result of wall slip the azimuthal velocity no longer linearly varies in the radial direction. However, under conditions pertinent to parallel-disk viscometry, it approximately remains linear in the normal direction. The implications of these observations on the processing of parallel-disk viscometry data are discussed. They indicate that the method of Yoshimura and Prud’homme (1988, “Wall Slip Corrections for Couette and Parallel-Disk Viscometers,” J. Rheol., 32(1), pp. 53–67) for the determination of the wall slip function remains valid but the simple and popular procedure for converting the measured torque into rim shear stress is likely to incur significant error as a result of the nonlinearity in the radial direction.
Vibration Analysis of a Floating Roof Taking Into Account the Nonlinearity of Sloshing
Authors: Utsumi M. , Ishida K.
Published: May 2008

The vibration of a floating roof hydroelastically coupled with nonlinear sloshing is analyzed. Influences of the nonlinearity of sloshing on the magnitude of stresses arising in a floating roof are investigated. Numerical results show that (i) neglecting the nonlinearity of sloshing significantly underestimates the magnitude of the stresses, even when the nonlinear effect is small for the roof displacement; and (ii) the underestimation associated with the use of the linear approximation becomes more marked with the decrease in the liquid depth. The reasons for these results are explained based on the fact that in the nonlinear sloshing, the modal component with circumferential wave number 2 is excited.
Optimal Winding Conditions of Flat Steel Ribbon Wound Pressure Vessels With Controllable Stresses
Authors: Zheng Chuanxiang , Lei Shaohui
Published: May 2008

Stress analysis of flat steel ribbon wound pressure vessels (FSRWPVs) is very difficult because they have a special discrete structure and complex pretensions exit in the flat steel ribbons, which are wound around the inner shell layer by layer. An analytical multilayered model for stress analysis is presented in this paper, which involves the effect of prestress in every flat steel ribbon layer as well as in the inner shell. Based on this model, an optimal design method for FSRWPV is suggested, which can assure a reasonable stress level and distribution along the wall thickness during the operation. A practical example of a large FSRWPV is finally given for illustration.
Stability Analysis of an Inflatable Vacuum Chamber
Authors: Barton Sean A.
Published: May 2008

A lightweight “inflatable” tensioned-membrane-structure vacuum container is proposed and its stability is analyzed. The proposed structure consists of a pressurized lobed cylindrical “wall” surrounding a central evacuated space. Stability is analyzed by discretizing the system and diagonalizing the second derivative of the potential energy. The structure is found to be stable when the pressure in the wall is greater than a critical pressure. When membranes are nonelastic, the critical pressure is found to be greater than the pressure required for equilibrium by a factor of 4∕3. When membranes have only finite stiffness, a first-order correction to the critical pressure is found. Preliminary experimental data show that a stable structure can be made in this way, and that the observed critical pressure is consistent with theory. It is also found that such structures can be designed to have net positive buoyancy in air.
Evaluation of Planar Harmonic Impedance for Periodic Elastic Strips of Rectangular Cross Section by Plate Mode Expansion
Authors: Danicki Eugene J.
Published: May 2008

A system of periodic elastic strips (each one considered as a piece of a plate) is characterized by a matrix relation between the Bloch series of displacement and traction at the bottom side of the system. Both these mechanical fields are involved in the boundary conditions at the contact plane between the strips and the substrate supporting a Rayleigh wave. The analysis exploits the mechanical field expansion over the plate modes, including complex modes; numerical results satisfy the energy conservation law satisfactorily. The derived planar harmonic Green’s function provides an alternative tool for investigation of surface waves propagation under periodic elastic strips, with respect to pure numerical methods mostly applied in the surface acoustic wave devices literature. Perfect agreement of the presented theory with the experimentally verified perturbation model of thin strips is demonstrated.
Modeling of Hydraulic Pipeline Transients Accompanied With Cavitation and Gas Bubbles Using Parallel Genetic Algorithms
Authors: Li Songjing , Yang Chifu , Jiang Dan
Published: May 2008

Mathematical models of pressure transients accompanied with cavitation and gas bubbles are studied in this paper to describe the flow behavior in a hydraulic pipeline. The reasonable prediction for pressure transients in a low pressure hydraulic pipeline largely depends on several unknown parameters involved in the mathematical models, including the initial gas bubble volumes in hydraulic oils, gas releasing and resolving time constants. In order to identify the parameters in the mathematical models and to shorten the computation time of the identification, a new method—parallel genetic algorithm (PGA)—is applied in this paper. Based on the least-square errors between the experimental data and simulation results, the fitness function of parallel genetic algorithms is programed and implemented. The global optimal parameters for hydraulic pipeline pressure transient models are obtained. The computation time of parallel genetic algorithms is much shorter than that of serial genetic algorithms. By using PGAs, the executing time is 20h. However, it takes about 204h by using GAs. Simulation results with identified parameters obtained by parallel genetic algorithms agree well with the experimental data. The comparison between simulation results and the experimental data indicates that parallel genetic algorithms are feasible and efficient to estimate the unknown parameters in hydraulic pipeline transient models accompanied with cavitation and gas bubbles.
Elastic Stress and Magnetic Field Concentration Near the Vertex of a
Soft-Ferromagnetic 2D Compound Wedge
Authors: Hasanyan Davresh , Qin Zhanming , Librescu Liviu
Published: May 2008

The problem of elastic stress and magnetic field concentration near the vertex of a compound wedge is modeled and investigated. The wedge is made of two isotropic dielectric soft-ferromagnetic materials and is immersed in a static magnetic field. The technique of eigenfunction series expansion is applied on the components of the elastic displacement field and the induced magnetic potentials near the vertex. It is shown that in this region, the magnetic susceptibility and the applied magnetic field have a strong influence on the elastic stress and magnetic field concentration. The results are instrumental toward actively controlling the stress concentration intensity via the applied magnetic field.
An Adaptive Meshless Method for Analyzing Large Mechanical Deformation and Contacts
Authors: Li Qiang , Lee Kok-Meng
Published: May 2008

Design for manufacturing of equipment (that handles deformable objects) and disposable medical devices (such as medical needles, optic fibers, and catheters for inserting into the human body) involves solving mechanical contact problems. Unlike rigid component manufacturing, which has been relatively well established, the handling of deformable bodies remains a challenging research. This paper offers an adaptive meshless method (MLM) for solving mechanical contact problems, which automatically insert additional nodes into large error regions identified in terms of mechanical stresses. This adaptive MLM employs a sliding line algorithm with penalty method to handle contact constraints. The method does not rely on small displacement assumptions; thus, it can solve nonlinear contact problems with large deformation. We validate the method by comparing results against those computed by using a commercial FEM software and analytical solution for two different situations, namely, large deformation and contact. Four practical applications are illustrated: large deflection of a compliant finger, mechanical contact, snap-fit assembly, and surgical needle insertion.
Jumps Across an Outgoing Spherical Shock Wave Front
Authors: Sano Yukio , Sano Tomokazu
Published: May 2008

The shock jump conditions have been used since Rankine published in 1870 and Hugoniot in 1889. However, these conditions, in which the geometrical effect is never included, may not be correctly applied to material responses caused by a spherical wave front. Here, a geometrical effect on jumps in radial particle velocity and radial stress across an outgoing spherical wave front is examined. Two types of jump equations are derived from the conservation laws of mass and momentum. The first equations of Rankine–Hugoniot (RH) type show that the geometrical effect may be neglected at distances of movement of the rear of the wave front that are more than ten times as long as the effective wave front thickness. Furthermore, using four conditions required to satisfy the RH jump conditions, which are contained in the RH type equations, a method is developed to judge the applicability of the RH jump conditions to the jumps. The second type equations for spherical wave fronts of general form are obtained by expressing a volumetric strain wave ε in the wave front by more general wave forms. In the neighborhood of the center of the wave front, for ε<0.09, radial particle velocity in the jump in any materials is inversely proportional to the square of a dimensionless distance from the center to the rear, and for ε<0.04, radial stress in the jump in some viscous fluids and solids is inversely proportional to the distance. In conclusion, an outgoing spherical wave front attenuates greatly near the center due to the geometrical effect as well as rarefaction waves overtaking from behind, while the geometrical effect is negligible at the specified positions that are distant from the center.