bluuebunny/crossref_metadata_2025 huggingface dataset:
Harnessing mobile communications innovations for water security
Authors: Hope Rob , Foster Tim , Money Alex , Rouse Michael
Published: February 2012

Water security aims to provide safe, reliable, affordable and sufficient water for people, agriculture, industry and ecosystems, subject to societal choices across related trade‐offs and risks. Managing resource risks, delivering effective governance, promoting financial sustainability and achieving social equity are central to achieving water security. We explore how innovations in mobile communications have created an inclusive, secure and low cost architecture for financial and data flows to reduce risk and enhance water security. In Africa, water security challenges associated with climate extremes and population growth outstripping improved water services’ access are juxtaposed with its global lead in mobile commerce innovations, including mobile water payments. Market driven expansion of mobile network coverage and low cost, mobile handsets mean more Africans will be connected to mobile phone services than those receiving improved water services in 2012. The confluence of rapid mobile network expansion, mobile phone ownership, mobile water payments and smart metering technologies offer new policy pathways to water security to accelerate progress on sustainable, safe water access, particularly for those in the greatest need and those most difficult to reach. We chart emerging mobile water innovations in Africa and policy implications in the region and beyond.

Policy Implications

 Mobile communication innovations offer an inclusive, secure and low cost architecture for financial and data flows that can reduce or share risk to enhance water security.

 The confluence of mobile network coverage, mobile phone ownership, mobile water payments and smart water metering technologies has significant but uncharted potential to enhance water security.

 Innovations are being driven by the commercial interests of mobile network operators with the distributional impacts and implications yet to be evaluated or shaped by policy and governance regimes.

 Living in rural and remote areas may no longer be synonymous with a higher risk of water insecurity as mobile connectivity could permit innovative management models at scale.
The all‐ceramic, inlay supported fixed partial denture. Part 3. Experimental approach for validating the finite element analysis
Authors: Thompson MC , Field CJ , Swain MV
Published: February 2012

In a previous study, the authors used a finite element analysis (FEA) to evaluate the stresses developed during the loading of an all‐ceramic, inlay supported fixed partial denture and compared it with the more traditional full crown supported prosthesis. To date there has been little research into correlating the responses of the numerical model against physical mechanical tests; such validation analysis is crucial if the results from the FEA are to be confidently relied upon. This study reports on the experimental methods used to compare with the FEA and thereby to validate the predictive fracture behaviour of the numerical model. This study also outlines the methods for manufacture and testing of the ceramic structure along with observations of the fracture tests. In addition the procedure used for developing the FEA model for the test system is outlined.
Inhibition of early biofilm formation by glass‐ionomer incorporated with chlorhexidine in vivo: a pilot study
Authors: Du X , Huang X , Huang C , Frencken JE , Yang T
Published: February 2012

Background:  This pilot study investigated the antibiofilm effects of glass‐ionomer cements (GICs) and resin‐modified glass‐ionomer cements (RMGICs) incorporated with chlorhexidine (CHX) in vivo.

Methods:  Experimental GICs and RMGICs containing 2% CHX were obtained by mixing CHX with the powder of GICs (CHXGIC) and RMGICs (CHXRMGIC). Four groups of specimens were prepared in a standardized size. After polishing and sterilization, they were bonded to the buccal surface of the molars in the first and second quadrant of volunteers and left untouched for 4 hours and 24 hours, respectively. The bacterial vitality of plaque was then analysed by confocal laser scanning microscopy (CLSM). The bacterial morphology and biofilm accumulation were determined by scanning electron microscopy (SEM). The pH value of biofilm was assessed by Plaque Indicator Kits.

Results:  CLSM analysis revealed that bacterial vitality of the biofilm on CHXGIC and CHXRMGIC was significantly lower than that on GIC and RMGIC. SEM analysis indicated that the morphology of bacteria on CHXGIC and CHXRMGIC was irregular. The pH value of biofilm on the experimental materials presented no statistically significant difference.

Conclusions:  Twenty‐four hour bacterial vitality on GICs and RMGICs with CHX are lower in micro‐organisms than on conventional GICs and RMGICs.
Dentists’ perceptions of a new local anaesthetic drug – articaine
Authors: Yapp KE , Hopcraft MS , Parashos P
Published: February 2012

Background:  Articaine is a new local anaesthetic drug introduced to the Australian dental market. The aim of this study was to elicit information regarding the use of articaine in Australia, and factors that influence attitudes towards adoption of new technology.

Methods:  A self‐administered postal questionnaire was sent to a stratified systematic sample of dentists who were members of the Australian Dental Association, with questions regarding details about articaine use and how influences such as education and scientific literature affect their adoption of new technology.

Results:  Of the sample, 53% responded and over 70% of dentists surveyed used articaine, with 95% and 97% of respondents identifying scientific literature and continuing professional development courses respectively as influencing factors in their adoption of new technology. The most common reason for not using articaine was no perceived advantage and the most influential factor that would encourage non‐users to start using articaine was a scientifically proven advantage. Senior clinicians, specialists and public sector dentists were less likely to use articaine.

Conclusions:  A majority of Australian dentists were using articaine and cited continuing professional development courses, scientific literature and anecdotal peer reports as being influential in their adoption of new technology.
Oral health inequalities in a national sample of Australian children aged 2–3 and 6–7 years
Authors: Kilpatrick NM , Neumann A , Lucas N , Chapman J , Nicholson JM
Published: February 2012

Background:  While inequalities in oral health are generally well documented, it is less clear whether such patterns are evident from early childhood. Using four measures of potential inequality, this study examined patterns in oral health for Australian children at ages 2–3 and 6–7 years.

Methods:  Cross‐sectional data from two cohorts of children in the Longitudinal Study of Australian Children (LSAC) were used to explore associations between reported oral health and four indicators of social disadvantage: socio‐economic position (SEP), residential remoteness, Indigenous status and non‐English speaking background.

Results:  For both cohorts, lower SEP and Indigenous status were associated with higher odds of poor oral health on all three indicators, and less accessible location was associated with increased odds for caries. Non‐English speaking background was associated with increased odds for caries experience in 2–3 year olds and non‐use of dental services in the older cohort. Inequalities were larger in the older cohort for socio‐economic position and toothbrushing.

Conclusions:  Marked social disparities in oral health appear as early as 2 years of age and remain evident in school‐age children. Interventions to reduce such disparities should start as early as possible.
Geographic redistribution of practice location of graduate dentists: a six‐year retrospective analysis (2004–2009)
Authors: Gurbuxani A , Kruger E , Tennant M
Published: February 2012

Background:  The purpose of this study was to analyse the geographic distribution of practice locations of graduate dentists from the University of Western Australia (UWA) over a period of six years.

Methods:  Using data from open access sources, all practice locations of the UWA’s dental graduates from 2004 to 2009 were located. All practice locations were measured at the postcode level and the distribution of graduates was analysed across variables such as SEIFA (a socio‐economic index of disadvantage) and ARIA (an index of accessibility and remoteness).

Results:  Of the 228 UWA graduates, an almost equal proportion of males (49.1%) and females (50.9%) graduated over the six‐year period. Of all the local graduates, 83% continued to practice in Western Australia, with 78% of the practice locations alone in ARIA 1 (highly accessible areas) and 22% of the graduates distributed among the remaining ARIA regions. Fifty‐one per cent of graduates practised in the 30% most affluent suburbs and only 11.5% practised in the most socio‐economically disadvantaged 30% suburbs. In SEIFA decile 10 (least disadvantaged areas), the highest numbers of practising dental graduates were also from the earliest graduates, with numbers steadily declining over the year of graduation from 2004 to 2009 (i.e. the most recent graduates).

Conclusions:  An apparent association exists between year of graduation and practice location, with more experienced dentists working in urban and higher socio‐economic areas.
Dental and periodontal complications of lip and tongue piercing: prevalence and influencing factors
Authors: Plessas A , Pepelassi E
Published: February 2012

Background:  The aim of this study was to compare the prevalence of lip and tongue piercing complications and explore the effect of ornament time wear period, habits, ornament morphology and periodontal biotype on the development of complications.

Methods:  One hundred and ten subjects with 110 lip and 51 tongue piercings were assessed for abnormal toothwear and/or tooth chipping/cracking (dental defects), gingival recession, clinical attachment loss and probing depth of teeth adjacent to the pierced site. Piercing habits (biting, rolling, stroking, sucking) were recorded.

Results:  Wear time and habits significantly affected the prevalence of dental defects and gingival recession. Pierced site significantly affected dental defects prevalence, with greater prevalence for tongue than lip piercing. Wear time significantly affected attachment loss and probing depth. Attachment loss and probing depth did not significantly differ between tongue and lip piercings. Gingival recession was significantly associated with ornament height closure and stem length of tongue ornaments. Periodontal biotype was not significantly associated with gingival recession, attachment loss and probing depth.

Conclusions:  Dental defects prevalence is greater for tongue than lip piercing. Gingival recession is similar for tongue and lip piercing. Longer wear time of tongue and lip piercing is associated with greater prevalence of dental defects and gingival recession, as well as greater attachment loss and probing depth of teeth adjacent to pierced sites. Ornament morphology affects gingival recession prevalence.
Modulation of epithelial tight junctions by TGF‐beta 3 in cultured oral epithelial cells
Authors: Ye P
Published: February 2012

Background:  Previous studies have indicated that transforming growth factor beta 3 (TGF‐β3) was strongly expressed both in the gingival epithelium and the poorly structured pocket epithelium.

Methods:  A comprehensive analysis of the profile of tight junction proteins was carried out by quantitative real‐time RT‐PCR, Western blot and paracellular permeability assays.

Results:  Active TGF‐β3 protein added to monolayers of cultured oral epithelial cells initially reduced the permeability to dextran (10 kDa), followed by an increase in permeability. Three hours after the addition of TGF‐β3, expression of genes encoding tight junction components was selectively up‐ or down‐regulated. In addition, up‐ or down‐regulation of expression of several tight junction associated proteins was observed, although the protein changes did not parallel changes in gene expression. To confirm that TGF‐β3 plays a role in epithelial barrier function, a selective Src family kinase inhibitor saracatinib (AZD0530) was added to cells treated with active TGF‐β3. Tight junction proteins claudins‐2, ‐20 and ZO‐2 were significantly decreased, but claudin‐4 and ‐18 were significantly increased.

Conclusions:  These results suggest that TGF‐β3 is involved in the modulation of epithelial barrier function by regulating assembly of tight junctions.
Non‐surgical periodontal therapy affects metabolic control in diabetics: a randomized controlled clinical trial
Authors: Moeintaghavi A , Arab HR , Bozorgnia Y , Kianoush K , Alizadeh M
Published: February 2012

Background:  Periodontal diseases and diabetes are two common diseases with high prevalence. Many clinicians have accepted the relationship between these two diseases. Some investigators have reported that periodontal treatment may enhance the metabolic control of diabetes. The effects of non‐surgical periodontal treatment on metabolic control in people with type 2 diabetes mellitus (DM2) were examined.

Methods:  Forty patients with DM2 and chronic periodontitis [mean age = 50.29 years; mean glycated haemoglobin (HbA1c) = 8.72] were randomly assigned to two groups. The treatment group (n = 22) received full‐mouth scaling and root planing, whereas the control group (n = 18) received no periodontal treatment. Gingival index (GI), plaque index (PI), probing pocket depth (PPD), clinical attachment level (CAL), fasting plasma glucose (FPG), HbA1c, total cholesterol (TC), triglyceride (TG) and cholesterol levels were recorded at baseline and compared to data collected three months later.

Results:  The groups did not differ in gender ratio, age or clinical parameters [PPD (p = 0.107), CAL (p = 0.888), PI (p = 0.180)] and biochemical markers at baseline [FPG (p = 0.429), HbA1c (p = 0.304), TG (p = 0.486), TC (p = 0.942), LDL (p = 0.856) and HDL (p = 0.881)]. FPG, HbA1c and clinical parameters differed between the treatment and control groups (p = 0.006, 0.003 and 0, respectively). From baseline to follow‐up (after three months), HbA1c levels decreased in the treated group (p = 0.003). In the same time period, FPG, GI, PPD and CAL increased in the control group (p = 0.016, 0.0, 0.0 and 0.004, respectively) but HbA1c did not change significantly.

Conclusions:  Non‐surgical periodontal therapy could improve metabolic control in diabetic patients.
Detection of CC17 Enterococcus faecium in Dogs and a Comparison with Human Isolates
Authors: Kwon K. H. , Moon B. Y. , Hwang S. Y. , Park Y. H.
Published: February 2012

Enterococcus faecium strains of clonal complex (CC) 17 were isolated from domestic dogs. The strains were more prevalent in infectious isolates than in colonized isolates, suggesting that strains of the CC17 lineage may have an advantage in causing infections in dogs. The pulsed field gel electrophoresis patterns of some dog and human isolates were over 90% similar. However, antimicrobial resistance patterns and virulence factors were not identical, which might reflect different use of antimicrobials in veterinary medicine or in host specificity.
Ca2+/calmodulin‐ dependent protein kinase II mediates transforming growth factor‐β‐induced hepatic stellate cells proliferation but not in collagen α1(I) production
Authors: An Ping , Tian Yihao , Chen Mingkai , Luo Hesheng
Published: February 2012

Aim:  Hepatic stellate cells (HSC) are the major players in hepatic fibrosis. As a most potent mitogen, transforming growth factor‐β (TGF‐β) strongly activates HSC and increases intracellular Ca2+ concentration. Here, we assessed the potential role of Ca2+/calmodulin‐dependent protein kinase II (CaMKII), a main downstream effector of the Ca2+ signal in liver fibrogenesis cascade.

Methods:  A human immortal HSC cell line, LX‐2, and primary rat hepatic stellate cells were used in current study. CaMKII blockage and Akt inhibition were performed by KN‐93/CaMKIIα siRNA and LY294002, respectively. HSC proliferation was detected by 5‐bromodeoxyuridine incorporation assay. Real‐time polymerase chain reaction, western blot and enzyme‐linked immunosorbent assay were used to measure mRNA, cellular protein and protein in medium, respectively. Procollagen α1(I) expression was detected by immunocytochemistry. The role of CaMKII on TGF‐β/Smad‐induced collagen α1(I) expression was determined by (CAGA)12‐MLP luciferase activity assay.

Results:  TGF‐β dramatically increased CaMKII mRNA, and total and phosphorylated CaMKII expression. KN‐93 and CaMKIIα siRNA suppressed TGF‐β‐mediated HSC proliferation. CaMKII interruption blocked TGF‐β‐elicited Akt activation. LY294002 arrested HSC proliferation and collagen α1(I) production but had no effect on CaMKII. Furthermore, CaMKII led to increased p21 and p27 expression. KN‐93 and CaMKIIα siRNA inhibited TGF‐β‐induced and basal collagen α1(I) production but had no effect on the activity of (CAGA)12‐MLP luciferase in response to TGF‐β stimulation.

Conclusion:  CaMKII is a pivotal signal in TGF‐β‐induced fibrogenic cascades by means of stimulating HSC proliferation, and involved in a basal collagen production. Therefore, CaMKII will be a potentially effective target in the development of therapeutic intervention strategies to attenuate hepatic fibrosis.
Hypocalcemia and HypovitaminosisDin Dogs with Induced Endotoxemia
Authors: Holowaychuk M.K. , Birkenheuer A.J. , Li J. , Marr H. , Boll A. , Nordone S.K.
Published: February 2012

Background

Hypocalcemia is a documented electrolyte disturbance in people and animals with sepsis, but its mechanism is poorly understood.

Objective

To investigate mechanisms of hypocalcemia in dogs with experimentally induced endotoxemia.

Animals

Six healthy mixed breed dogs were included in this nonrandomized, placebo‐controlled, crossover study.

Methods

Dogs initially were injected with placebo (0.9%NaCl; 1 mL,IV) and then lipopolysaccharide (LPS; 2 μg/kg,IV) after a 5‐day washout period. Blood and urine samples were collected for measurement of serum total calcium (tCa), ionized calcium (iCa), total magnesium (tMg), ionized magnesium (iMg), parathyroid hormone (PTH), 25‐hydroxyvitaminD(vitaminD), venous blood gases, and fractional excretion (FE) of calcium.

Results

AfterLPSadministration, body temperature increased and blood pressure decreased. BothiCa andtCa decreased (P < .01), butiMg was not significantly different between control andLPStreatments.PTHconcentrations increased (P < .01) and vitaminDconcentrations decreased (P < .01). VenouspH, bicarbonate, base excess, and blood glucose also decreased (P < .01). UrinetCa concentration was below the limit of detection for all dogs afterLPSadministration.

Conclusions

Hypocalcemia occurs during endotoxemia in dogs and is associated with hypovitaminosisD. Hypomagnesemia, hypoparathyroidism, alkalosis, and increased calciuresis are not associated with hypocalcemia in endotoxemic dogs.
Characterization of the Genetic Basis for Autosomal Recessive Hereditary Nephropathy in theEnglishSpringerSpaniel
Authors: Nowend K.L. , Starr‐Moss A.N. , Lees G.E. , Berridge B.R. , Clubb F.J. , Kashtan C.E. , Nabity M.B. , Murphy K.E.
Published: February 2012

Background

Autosomal recessive hereditary nephropathy (ARHN) was diagnosed in 2EnglishSpringerSpaniels (ESS), a breed not previously reported to be affected by hereditary nephropathy (HN).

Objective

To identify and characterize the genetic cause ofARHNinESS.

Animals

Sixty‐threeESS(2 withARHN, 2 obligate carriers, and 59 others), 2 mixed‐breed dogs with X‐linkedHN, and 2EnglishCockerSpaniels (ECS) withARHNwere included.

Methods

ARHNwas diagnosed based on transmission electron microscopy and immunostaining of kidney.DNAfrom affected dogs was screened for the mutation known to causeARHNinECS. Quantities ofCOL4A3,COL4A4, andCOL4A5mRNAtranscripts in renal cortex were determined using quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR) forARHN‐affected dogs and 7 other dogs. The coding regions ofCOL4A3andCOL4A4were sequenced for the 2ARHN‐affectedESSand an unaffected dog. Exon 30 ofCOL4A4was sequenced for all 63ESS.

Results

qRT‐PCRindicated a significant reduction in transcript levels of bothCOL4A3andCOL4A4mRNAin the kidney ofARHN‐affectedESS. Sequencing identified a single nucleotide substitution inCOL4A4at base 2806 resulting in a premature stop codon. Thirteen of 25 related dogs were identified as carriers.

Conclusions and Clinical Importance

A mutation highly likely to causeARHNinESShas been identified.
Evaluation of the Oral Antimitotic Agent (ABT‐751) in Dogs with Lymphoma
Authors: Silver M. , Rusk A. , Phillips B. , Beck E. , Jankowski M. , Philibert J. , Hahn K. , Hershey E. , McKeegan E. , Bauch J. , Krivoshik A. , Khanna C.
Published: February 2012

Background

ABT‐751 is a novel orally available antimitotic agent that targets microtubule polymerization. This mechanism may suggest potential activity in canine lymphoma.

Objective

Determine a maximum tolerated dose for ABT‐751, and assess long‐term tolerability and activity in canine lymphoma.

Animals

Thirty dogs with newly diagnosed (n = 19) or relapsed (n = 11) non‐Hodgkin's lymphoma.

Methods

Dogs (n = 11) were enrolled in a rapid dose escalation study to define the maximum tolerated dose. Upon definition of a maximally tolerated dose, a cohort expansion of 19 dogs allowed verification of long‐term tolerability and assessment of activity. Study endpoints in the cohort expansion included chronic tolerability, response rate, response duration, and time to progression. Additional endpoints included serum pharmacokinetics, lymph node drug concentrations, and changes in circulating endothelial cells.

Results

The maximum tolerated dose of ABT‐751 was 350 mg/m2 PO q24h. Dose‐limiting toxicities included vomiting and diarrhea, which resolved with a schedule adjustment to 350 mg/m2 PO q48h. ABT‐751 was consistently detected in lymphoma tissue samples from dogs treated at or above the maximum tolerated dose. In the cohort expansion, objective responses were seen in 3/15 (20%) dogs with a response duration ranging from 21 to 111 days. Decreases in circulating endothelial cells were seen in 10 dogs at day 7 (2 responding dogs and 8 nonresponding dogs).

Conclusion

ABT‐751 was well tolerated at 350 mg/m2 PO q24h for 7 days and then q48h thereafter. Activity of ABT‐751 suggested a rationale for additional studies of ABT‐751 as part of a combination chemotherapy protocol for lymphoma or other canine cancers.
Regulation of polysynaptic subthalamonigral transmission by D2, D3 and D4 dopamine receptors in rat brain slices
Authors: Shen Ke‐Zhong , Johnson Steven W.
Published: February 2012

Key points 

Symptoms of Parkinson's disease are associated with increased bursting activity in the subthalamic nucleus and substantia nigra zona reticulata (SNR).

In slices of rat brain, a single electrical stimulus to the STN evokes a complex EPSC and bursts of action potentials in SNR neurons.

We show that dopamine acts at D2‐like receptors to cause marked and reversible inhibition of the complex EPSC.

Dopamine also inhibited stimulus‐evoked bursts of action potentials more than reducing spontaneous firing.

Inhibition of synaptically generated burst firing by D2 receptor agonists may be a clinically important mechanism in the treatment of Parkinson's disease.
Excitatory inputs to four types of spinocerebellar tract neurons in the cat and the rat thoraco‐lumbar spinal cord
Authors: Shrestha Sony Shakya , Bannatyne B. Anne , Jankowska Elzbieta , Hammar Ingela , Nilsson Elin , Maxwell David J.
Published: February 2012

Key points 

For co‐ordinated limb movements, the brain needs to be provided with continuous feedback information from the spinal cord.

We investigated the types of information forwarded to the cerebellum by four populations of neurons.

Cells were classified according to their electrophysiological properties in cats and location within the grey matter in rats.

We used immunochemistry to identify excitatory (glutamatergic) terminals and to differentiate between terminals of peripheral sensory fibres and terminals of spinal or supraspinal neurons in contact with labelled cells.

Our results revealed marked differences between these four populations.

These findings improve our understanding of the functional connectivity between the spinal cord and the cerebellum and provide new insights into the role of the cerebellum in controlling limb movements.
Heterosynaptic plasticity induced by intracellular tetanization in layer 2/3 pyramidal neurons in rat auditory cortex
Authors: Lee Christopher M. , Stoelzel Carl , Chistiakova Marina , Volgushev Maxim
Published: February 2012

Key points summary 

Learning systems equipped with Hebbian‐type associative plasticity are prone to runaway dynamics of synaptic weights and lack mechanisms for synaptic competition; these problems can be resolved by heterosynaptic plasticity: changes at synapses which were not active during the induction.

We show that in layer 2/3 pyramidal neurons from auditory cortex a purely postsynaptic challenge, intracellular tetanization, can induce heterosynaptic plasticity; similar to visual cortex, plasticity direction depends on initial properties of synapses: inputs with initially low release probability tend to potentiate, while those with initially high release probability tend to depress.

Induction of heterosynaptic plasticity requires intracellular Ca2+ rise and its maintenance involves presynaptic changes, which depend on the nitric oxide signalling pathway.

We conclude that heterosynaptic plasticity is a common property of supragranular pyramidal neurons mediating cortico‐cortical connections in both auditory and visual cortices; it may serve as a mechanism of synaptic weight normalization and synaptic competition in these cortical regions.
Binary, Gravity-Flow Film Condensation
Authors: Sparrow E. M. , Marschall E.
Published: February 2012

A predictive theory for condensation of a binary mixture on a cooled vertical plate has been formulated on the basis of the conservation laws and other fundamental physical principles. The formulation involves the analysis of the transport processes in the condensate film and in the vapor boundary layer, along with conditions of continuity, conservation, and equilibrium at the liquid-vapor interface. The analytical method is applied to the condensation of saturated binary mixtures of methanol and water vapor, and heat transfer results are obtained for a range of operating conditions. For large condensation rates, the heat transfer can be calculated by a simplified method which bypasses the detailed analysis of the vapor boundary layer.
Free Convective Flow Patterns in Cylindrical Annuli
Authors: Powe R. E. , Carley C. T. , Bishop E. H.
Published: February 2012

The results of all available experimental investigations into the characteristics of free convective flow of air between horizontal isothermal concentric cylinders are reviewed and several discrepancies are pointed out. An experimental study is described which was directed at resolving these discrepancies and categorizing the several flow patterns which have been observed. Using six different cylinder sets and varying both the annulus pressure and temperature difference between the cylinder surfaces, a range of Grashof numbers (based on annulus width) from 300 to 3.4 × 106 was achieved. The resulting air flow patterns were made visible with the use of tobacco smoke and are documented by written descriptions, photographs, motion pictures, and quantitative data. One steady and three unsteady flow patterns were observed and comparison with the results of other investigators is presented. A chart is presented which allows prediction of the type of unsteady flow that will occur for a wide range of cylinder combinations and annulus operating conditions. A comparison with cylinders in forced cross-flow is used to satisfactorily predict the onset of one of the unsteady flow patterns. Also, the flow patterns observed experimentally are compared to those predicted by an available analytical solution.
Heat Transfer in Turbulent Pipe Flow With Optically Thin Radiation
Authors: Landram C. S. , Greif R. , Habib I. S.
Published: February 2012

The problem considered is the determination of the heat transfer in fully developed turbulent flow of a radiating optically thin gas in a circular tube. The radiation problem is formulated in terms of the Planck mean and the modified Planck mean coefficients and the temperature profiles and Nusselt numbers have been determined. It is shown that the simple constant shear, constant heat flux formulation yields results that are in very good agreement with more complex calculations.
Effect of Vibration on Heat Transfer From Spheres
Authors: Baxi C. B. , Ramachandran A.
Published: February 2012

The effect of vibration on free and forced convection heat transfer from spheres was investigated. Test spheres made of copper were subjected to sinusoidal vibration in the vertical plane, this being perpendicular to the direction of airstream in the case of forced convection studies. In free convection studies the amplitude of vibration was varied from 4 mm to 25.5 mm and the frequency of vibration from 150 cpm to 930 cpm. It was found that the effect of vibration on Nusselt number was negligible for values of vibrational Reynolds number less than 200. For values of vibrational Reynolds number greater than 200, the vibration increased the heat transfer coefficient considerably and values of heat transfer coefficients as high as seven times the free convection values without vibration were obtained. The following correlations were obtained for heat transfer from spheres to air: freeconvectionwithoutvibration,NNu=2+0.401(NGr)0.25for4×103<NGr<6×104 and free convection with vibration: hvho=0.83(NRe)v0.5(a/D)0.1(NGr)0.251.28 In the case of forced convection studies with vibration, the amplitude of vibrations varied between 4 mm and 12.4 mm, and the frequency of vibration from 200 cpm to 1600 cpm. The flow velocity was varied from 24.5 ft/sec to 84 ft/sec. The results in the absence of vibration could be represented by: NNu = 0.304 (NRe)0.56 or NNu = 2 + 0.222 (NRe)0.587 in the range 6 × 103 < NRe < 3.3 × 104. Nusselt numbers were not found to be affected by the imposition of vibrational velocity even as high as 19.6 percent of the flow velocity.
Flow in the Hydrodynamic Entrance Region of Ducts of Arbitrary Cross Section
Authors: Fleming David P. , Sparrow E. M.
Published: February 2012

A general method of analysis is presented for determining the developing velocity field and pressure drop for laminar flow in the entrance region of ducts having arbitrary cross sections. Application of the solution method is made to rectangular ducts and to triangular ducts. Available experimental data are compared with the analytical results and good agreement is found to prevail. Development characteristics for six ducts are brought together and compared, and various trends are identified.
Transient Freezing of Liquids in Forced Flow Inside Circular Tubes
Authors: O¨zis¸ik M. N. , Mulligan J. C.
Published: February 2012

The transient freezing of a liquid flowing inside a circular tube is investigated analytically under the assumption of a constant tube wall temperature which is lower than the freezing temperature, constant properties, a slug-flow velocity profile and quasisteady state heat conduction in the solid phase. The variation of the local heat flux and the profile of the solid-liquid interface during freezing has been determined as a function of time and position along the tube. The analysis produced steadystate heat transfer rates and profiles for the solid-liquid interface which agreed well with experiments.
Free Convection Through Vertical Plane Layers—Moderate and High Prandtl Number Fluids
Authors: MacGregor R. K. , Emery A. F.
Published: February 2012

The results of numerical computations are presented for free convection under isothermal wall and constant-heat-flux wall-boundary conditions. The effects of the Prandtl, Grashof, and Rayleigh numbers, aspect ratio, and variable properties are described. Experimental measurements of net heat transfer through vertical plane layers and of velocity and temperature profiles are given for Prandtl numbers of 1 to 20,000. A comparison of the laminar data with the numerical results shows excellent correlation.
An Analysis of Film Condensation, Film Evaporation, and Single-Phase Heat Transfer for Liquid Prandtl Numbers From 10−3 to 104
Authors: Kunz H. R. , Yerazunis S.
Published: February 2012

Annular two-phase flow inside of circular tubes is analyzed for a wide range of film Reynolds and Prandtl numbers. This analysis is applied to the prediction of film heat transfer coefficients and film thicknesses for the cases of condensation and evaporation of pure substances inside tubes, two-component flow in tubes, and condensing falling films on vertical surfaces. The analysis is also extended to single-phase flow in tubes. Extensive comparisons are made with experimental and theoretical results of other investigators, indicating good agreement if consideration is given to liquid-vapor interfacial resistance to heat flow for cases involving phase transformation.
Heat Transfer and Pressure Drop in Tape-Generated Swirl Flow of Single-Phase Water
Authors: Lopina R. F. , Bergles A. E.
Published: February 2012

This paper summarizes the results of an investigation of the heat-transfer and pressure drop characteristics of single-phase water in tape-generated swirl flow. Extensive data are reported for electrically heated or water-cooled tubular test sections with tight fitting, full length tapes with twist ratios from 2.5 to 9.2. A method was developed for predicting the heat-transfer coefficient for swirl flow based upon the premise that the observed improvement is due primarily to: (a) the increased flow path created by the tape, (b) the increased circulation created with heating due to the large centrifugal force, and (c) the tape fin effect. The experimental results of this and previous swirl flow investigations are in good agreement with the prediction method. Correlations are also presented for adiabatic and diabatic friction factors. Heat-transfer and friction data are combined in a constant pumping power comparison for swirl and straight flow, which indicates that improvements of 20 percent can readily be obtained with swirl flow.
Laminar, Transition, and Turbulent Boundary-Layer Heat-Transfer Measurements With Wall Cooling in Turbulent Airflow Through a Tube
Authors: Back L. H. , Cuffel R. F. , Massier P. F.
Published: February 2012

Heat-transfer measurements were made along the wall in the thermal entrance region of a high-temperature turbulent airflow through a cooled tube 8.6 dia long. There was simultaneous development of the velocity and temperature profiles along the tube, the boundary-layer thickness at the inlet being small, compared to the tube radius. The measurements, made over a range of Reynolds numbers based on the tube diameter ReD from 7 × 104 to 106 and wall-to-gas temperature ratio Tw/Tt from 1/3 to 2/3, included natural boundary-layer transition data in the laminar, transition, and turbulent boundary-layer regions, and forced transition data obtained with a trip at the tube inlet. Although the inability to predict boundary-layer transition precludes a general correlation of the data, a fair correlation of the transitional data was obtained by accounting for the effective origin of the boundary layer. Transition Reynolds numbers, on the order of those found for flow over a flat plate, increased with ReD and decreased with wall cooling; i e., decreasing Tw/Tv In the turbulent boundary-layer region, both the natural transition data and tripped data were in general correspondence with the trend of a constant-property flat-plate prediction. However, the turbulent boundary-layer heat-transfer group with properties evaluated at the core flow temperature increased with wall cooling. Other investigations in the turbulent flow region are discussed in light of these measurements.
Laminar Film Condensation of a Flowing Vapor on a Horizontal Cylinder at Normal Gravity
Authors: Denny V. E. , Mills A. F.
Published: February 2012

An analytical solution, based on the Nusselt assumptions, has been obtained for laminar film condensation of a flowing vapor on a horizontal cylinder. In so doing, a reference temperature for evaluating locally variable fluid properties is defined in the form Tr = Tw + α (Ts − Tw) and accounts for both the effects of fluid property variations and minor errors introduced by the assumptions in the analysis. Verification was obtained by comparison with exact numerical solutions based on a finite-difference analog to the conservation equations in boundary-layer form. In the analytical as well as the numerical developments, vapor drag was accounted for through an asymptotic solution of the vapor boundary layer under strong suction. It was found that, for angles up to 140 deg, there was less than a 2 percent discrepancy between the analytical predictions and the numerical results. As 180 deg is approached an increased discrepancy is expected due to a gross violation of the Nusselt assumptions. The values of the reference parameter α, which were previously derived for condensation on a vertical surface, were found to be appropriate for the horizontal cylinder as well.
Natural Convection Local Heat Transfer on Constant-Heat-Flux Inclined Surfaces
Authors: Vliet G. C.
Published: February 2012

Experimental local heat transfer data are presented for natural convection on constant-heat-flux inclined surfaces using water and air. The data extend to Grz* Pr = 1016, cover angles from the vertical to 30 deg with the horizontal, and include the laminar, transition, and turbulent regimes. In the laminar regime the data correlate well with vertical plate theory when the gravitational component parallel to the surface is used. Transition is strongly affected by inclination, the transition Grz* Pr decreasing from near 1013 for vertical surfaces to approximately 108 for a surface at 30 deg to the horizontal. The turbulent local heat transfer data correlate using the actual gravity rather than the parallel component, and indicates a change in the Grz* Pr exponent from near 0 22 for a vertical surface to approximately 1/4 as the inclination decreases. The turbulent data can be correlated quite well by Nuz = 0.30(Grz* Pr)0.24.
Hyperbolic Heat-Conduction Equation—A Solution for the Semi-Infinite Body Problem
Authors: Baumeister K. J. , Hamill T. D.
Published: February 2012

This theoretical paper determines the effect of the propagation velocity of heat on the temperature and heat-flux distribution in a semi-infinite body due to a step change in temperature at the surface. The solution yields a maximum but finite heat flux under the conditions of a step change. This is contrary to the infinite value predicted by the error function solution to the Fourier transient conduction equation. In addition, assuming convection is conduction limited, an upper limit for convective heat transfer coefficients is postulated.
Heat Transfer to Mercury Flowing In Line Through an Unbaffled Rod Bundle: Experimental Study of the Effect of Rod Displacement on Rod-Average Heat Transfer Coefficients
Authors: Hlavac P. J. , Dwyer O. E. , Helfant M. A.
Published: February 2012

An experimental study of heat transfer to mercury flowing in line through an unbaffled rod bundle was carried out. The “rods” were special electrical heaters whose claddings had different thicknesses and thermal conductivities. The experiments were carried out under a thermal boundary condition approaching that of uniform heat flux in all directions at the inner wall of the rod cladding. It was found that displacement of a rod from its symmetrical position can result in a large reduction in its average heat transfer coefficient. This reduction increases exponentially with the amount of displacement. For a given direction and amount of displacement, the reduction is little affected by variations in cladding thickness and conductivity but is affected considerably by flow rate. Not only does the displaced rod suffer a reduction in its own average heat transfer coefficient, but so do those toward which it is displaced. At the same time, the average coefficients of the rods from which it is displaced remain about the same. Thus the overall average coefficient of the group of affected rods goes down when a single rod is displaced.
The Stability of Water Flow Over Heated and Cooled Flat Plates
Authors: Wazzan Ahmed R. , Okamura T. , Smith A. M. O.
Published: February 2012

The theory of two-dimensional instability of laminar flow of water over solid surfaces is extended to include the effects of heat transfer. The equation that governs the stability of these flows to Tollmien-Schlichting disturbances is the Orr-Sommerfeld equation “modified” to include the effect of viscosity variation with temperature. Numerical solutions to this equation at high Reynolds numbers are obtained using a new method of integration. The method makes use of the Gram-Schmidt orthogonalization technique to obtain linearly independent solutions upon numerically integrating the “modified Orr-Sommerfeld” equation using single precision arithmetic. The method leads to satisfactory answers for Reynolds numbers as high as Rδ* = 100,000. The analysis is applied to the case of flow over both heated and cooled flat plates. The results indicate that heating and cooling of the wall have a large influence on the stability of boundary-layer flow in water. At a free-stream temperature of 60 deg F and wall temperatures of 60, 90, 120, 135, 150, 200, and 300deg F, the critical Reynolds numbers Rδ* are 520, 7200, 15200, 15600, 14800, 10250, and 4600, respectively. At a free-stream temperature of 200F and wall temperature of 60 deg F (cooled case), the critical Reynolds number is 151. Therefore, it is evident that a heated wall has a stabilizing effect, whereas a cooled wall has a destabilizing effect. These stability calculations show that heating increases the critical Reynolds number to a maximum value (Rδ* max = 15,700 at a temperature of TW = 130 deg F) but that further heating decreases the critical Reynolds number. In order to determine the influence of the viscosity derivatives upon the results, the critical Reynolds number for the heated case of T∞ = 40 and TW = 130 deg F was determined using (a) the Orr-Sommerfeld equation and (b) the present governing equation. The resulting critical Reynolds numbers are Rδ* = 140,000 and 16,200, respectively. Therefore, it is concluded that the terms pertaining to the first and second derivatives of the viscosity have a considerable destabilizing influence.
A Study of Wall-Turbulence Phenomena Using Hot-Film Sensors
Authors: Armistead R. A. , Keyes J. J.
Published: February 2012

Flush-mounted hot-film sensors were used to study local turbulence-induced fluctuations in the rate of heat transfer in pipe flow of water for a Reynolds number range of 11,000 to 170,000. Determinations were made of power spectral density, characteristic frequency (obtained from the rate at which the signal crossed its zero level), amplitude density, and intensity of the heat-transfer fluctuations. Studies of the relationship between the heat-transfer fluctuations in the vicinity of the wall indicated that a significant correlation existed which systematically decreased as the anemometer was moved from moderate distances upstream to moderate distances downstream of the wall sensor. Evidences of a periodic component were observed in the autocorrelation curves of velocity fluctuations in the vicinity of the wall for a Reynolds number of 52,000. The period determined was of the same order of magnitude as that predicted by Einstein and Li [10]2 and Black [11] sublayer flow models.
Theoretical Model for Predicting the Transient Response of the Mixture-Vapor Transition Point in Horizontal Evaporating Flow
Authors: Wedekind G. L. , Stoecker W. F.
Published: February 2012

A horizontal tube evaporator in which complete vaporization takes place can be divided into two distinct regions—a two-phase region and a superheat region. The mixture-vapor transition point refers to the boundary between these two regions. Experimental evidence is presented which indicates that, during steady as well as transient flow conditions, the motion of the mixture-vapor transition point is of an oscillatory nature. Furthermore, the amplitudes of the oscillations appear to be sufficiently random to preclude the possibility of predicting an instantaneous position. Therefore, a theoretical model is proposed for predicting the transient response of the mean position of the transition point. Experimental validation of the theoretical model is reasonably well established.
Laminar Free Convection From a Downward-Projecting Fin
Authors: Lock G. S. H. , Gunn J. C.
Published: February 2012

A theoretical analysis of conduction through and free convection from a tapered, downward-projecting fin immersed in an isothermal quiescent fluid is presented. The problem is solved by assuming quasi-one-dimensional heat conduction in the fin and matching the solution to that of the convection system, which is treated as a boundary layer problem. For an infinite Prandtl number, solutions are derived which take the form of a power law temperature distribution along the fin. The effect of this power (n) on heat transfer, drag, and the corresponding boundary layer profiles is discussed. It is shown that n is independent of the fin profile and dependent on a single nondimensional group χ. The theoretical results for infinite Prandtl number are compared with corresponding results derived from previous work using a Prandtl number of unity. The effect of Prandtl number on the determination of n and consequently the fin effectiveness is found to be extremely small. The results of an experimental program are also presented. These consist of temperature profiles and the n — χ relation for different fin geometries and surrounding fluids. Comparison with the theoretical predictions reveals good agreement.
An Experimental Study of Forced-Convection Heat Transfer From a Sphere to Liquid Sodium
Authors: Witte L. C.
Published: February 2012

Experimental heat-transfer rates from spheres moving through liquid sodium have been obtained. The experimental data were obtained by a transient technique in which a heated metal sphere was passed through a pool of liquid sodium. Heat-transfer rates up to 3.58 × 106 Btu/(hr)(ft2) were calculated from the experimental measurements. Reynolds numbers, based on the sphere velocity and diameter, ranged from 35,000 to 153,000. The experimental data were correlated by an expression similar to theoretical expressions obtained from potential-flow theory.
Momentum Flux in Two-Phase Flow
Authors: Andeen G. B. , Griffith P.
Published: February 2012

Measurements of the momentum flux through a section of pipe with steam-water and air-water two-phase flow are reported. The results are used to evaluate the utility of various two-phase flow models and the underlying assumptions. The slip model was found to yield low values. The homogeneous model correlated the data well, but this is because of compensating errors in the assumptions. The steady flow assumption of most two-phase flow models is considered to be inadequate for prediction of the momentum flux at low quality. At higher quality the velocity profile is the dominant consideration.