bluuebunny/crossref_metadata_2025 huggingface dataset:
The HLA locus contains novel foetal susceptibility alleles for congenital heart block with significant paternal influence
Authors: Meisgen S. , Östberg T. , Salomonsson S. , Ding B. , Eliasson H. , Mälarstig A. , Alfredsson L. , Klareskog L. , Hamsten A. , Olsson T. , Axelsson T. ,   The Swedish Congenital Heart Block Study Group, Gadler F. , Jonzon A. , Sonesson S.‐E. , Kockum I. , Wahren‐Herlenius M.
Published: December 2013

Objective

The main aim of this study was to identify foetal susceptibility genes on chromosome six for Ro/SSA autoantibody‐mediated congenital heart block.

Subjects and Design

Single nucleotide polymorphism (SNP) genotyping of individuals in the Swedish Congenital Heart Block (CHB) study population was performed. Low‐resolution HLA‐A, ‐Cw and ‐DRB1 allele typing was carried out in 86 families comprising 339 individuals (86 Ro/SSA autoantibody‐positive mothers, 71 fathers, 87 CHB index cases and 95 unaffected siblings).

Results

A case–control comparison between index cases and population‐based out‐of‐study controls (n = 1710) revealed association of CHB with 15 SNPs in the 6p21.3 MHC locus at a chromosome‐wide significance of P < 2.59 × 10−6 (OR 2.21–3.12). In a family‐based analysis of association of SNP markers as well as distinct MHC class I and II alleles with CHB, HLA‐DRB1*04 and HLA‐Cw*05 variants were significantly more frequently transmitted to affected individuals (P < 0.03 and P < 0.05, respectively), whilst HLA‐DRB1*13 and HLA‐Cw*06 variants were significantly less often transmitted to affected children (P < 0.04 and P < 0.03). We further observed marked association of increased paternal (but not maternal) HLA‐DRB1*04 transmission to affected offspring (P < 0.02).

Conclusions

HLA‐DRB1*04 and HLA‐Cw*05 were identified as novel foetal HLA allele variants that confer susceptibility to CHB in response to Ro/SSA autoantibody exposure, whilst DRB1*13 and Cw*06 emerged as protective alleles. Additionally, we demonstrated a paternal contribution to foetal susceptibility to CHB for the first time.
Identification of CNS Neurons Innervating the Levator Ani and Ventral Bulbospongiosus Muscles in Male Rats
Authors: Dobberfuhl Amy D. , Oti Takumi , Sakamoto Hirotaka , Marson Lesley
Published: December 2013

Introduction

The pelvic striated muscles play an important role in mediating erections and ejaculation, and together these muscles compose a tightly coordinated neuromuscular system that is androgen sensitive and sexually dimorphic.

Aim

To identify spinal and brains neurons involved in the control of the levator ani (LA) and bulbospongiosus (BS) in the male adult and preadolescent rat.

Methods

Rats were anesthetized, and the transsynaptic retrograde tracer pseudorabies virus (PRV) was injected into the LA muscle of adults or the ventral BS muscle in 30-day-old rats. After 3–5 days rats were sacrificed, and PRV-labeled neurons in the spinal cords and brains were identified using immunohistochemistry. The presence of gastrin-releasing peptide (GRP) in the lumbar spinal neurons was examined.

Main Outcomes Measures

The location and number of PRV-labeled neurons in the spinal cord and brain and GRP colocalization in the lumbar spinal cord.

Results

PRV-labeled spinal interneurons were found distributed throughout T11-S1 of the spinal cord, subsequent to dorsal medial motoneuron infection. The majority of spinal interneurons were found in the lumbosacral spinal cord in the region of the dorsal gray commissure and parasympathetic preganglionic neurons. Preadolescent rats had more PRV-labeled spinal interneurons at L5-S1 where the motoneurons were located but relatively less spread rostrally in the spinal cord compared with adults. Lumbar spinothalmic neurons in medial gray of L3-L4 co-localized PRV and GRP. In the brain consistent labeling was seen in areas known to be involved in male sexual behavior including the ventrolateral medulla, hypothalamic paraventricular nucleus, and medial preoptic area.

Conclusion

Common spinal and brain pathways project to the LA and BS muscles in the rat suggesting that these muscles act together to coordinate male sexual reflexes. Differences may exist in the amount of synaptic connections/neuronal pathways in adolescents compared with adults.
Supratentorial cortical ependymoma: Case series and review of the literature
Authors: Liu Zhiguo , Li Jing , Liu Zhiyan , Wang Qian , Famer Peter , Mehta Ashesh , Chalif David , Wang Yunyan , Li Jian Yi
Published: December 2013

Supratentorial cortical ependymoma (CE), a rare type of ependymoma, is located in the superficial cortex. We reported 11 patients (six female and five male) with CE. The age of the patients ranged from 2 to 63 years old with a median age of 47 years at the time of diagnosis. On MRI, enhancement was noted in all cases with solid appearance in six cases, and solid and cystic appearance in five cases. The frontal and parietal regions were the most common locations for CE. On histology, two were low‐grade (WHO grade II) and nine were WHO grade III anaplastic ependymomas. Some tumors exhibited clear cell, spindle (tanycytic) and giant cell morphologies, as well as the classic ependymoma morphology. Dura‐based tumor nodules and even tumor dissemination along the dura can be seen in CEs. Low grade CEs have a higher likelihood to present with seizures, a lower likelihood to cause brain edema, tumor recurrence and lower mortality than anaplastic ependymomas. While difficult, anaplastic CEs may be distinguished from glioblastoma by a clear interface between tumor and adjacent brain tissue, relative uniformity of tumor cell nuclei and immunopositivity for epithelial membrane antigen and/or CD99. As is the case for ependymomas in general, gross total resection is still the treatment of choice for CEs.
Manufacturer changes lead to clinically important differences between two editions of the TNO stereotest
Authors: van Doorn Louise L A , Evans Bruce J W , Edgar David F , Fortuin Marten F
Published: December 2013

Purpose

Stereoacuity tests used in clinical practice should be repeatable and reproducible. However, it has been observed in a clinical setting that new editions of the TNO stereotest appear to give different values from those obtained using previous versions. The purpose of the present research was to investigate this observation.

Methods

One hundred and twenty‐one Dutch subjects, 88 (73%) females and 33 (27%) males, with an average age of 34.0 years (range 18–55) had their stereoacuity measured using two different versions of the TNO stereoacuity test (TNO 13 and TNO 15). The TNO was tested in a counterbalanced order so that consecutive subjects started with alternate editions to avoid bias.

Results

There was a significant difference (p < 0.001) between the median value for stereoacuity measured with TNO 13 (30 s of arc) and TNO 15 (60 s of arc). The bias between the two test versions was −0.23 Log arcseconds (95% limits of the differences: 0.15 to −0.60 Log arcseconds).

Conclusion

This study reveals that results obtained with two different editions of a commonplace stereoacuity test are not comparable. New versions come on the market at regular intervals and the assumption that they will give the same results as previous versions may not be valid. Besides the statistically significant difference between the TNO 13 and TNO 15, the Bland‐Altman plot also showed a considerable bias and the 95% limits of the differences between the TNO 13 and TNO 15 are more than two steps on the Log arcsecond scale. This difference between two editions of the TNO stereotests is not clinically acceptable and therefore it is inappropriate to use the two versions of the test interchangeably. It is important in both research and clinical records to specify the edition of the TNO test used.
Gender differences in childhood food preference: Evaluation using a subjective picture choice method
Authors: Kimura Shinji , Endo Yuri , Minamimae Keiko , Kanzaki Susumu , Hanaki Keiichi
Published: December 2013

Background

A preference for calorie‐dense food in men seems to be closely linked with a considerably higher incidence of obesity in adulthood for men than women, but it is not clear in which life stage the gender differences in food preference begin to appear. In order to clarify this, a picture choice method has been developed that is designed to evaluate food preferences or interests in children based on their subjective choices.

Methods

In total, 486 children aged 6–12 years were enrolled. To evaluate food interest, children were instructed to choose any 10 from 36 pictures in the panel showing 10 different foods and 26 other things. The number of foods chosen was set as the food interest score. For food preference, they were also instructed to choose any 10 from 36 pictures in the other panel depicting 36 different foods. For the 10 foods chosen, Japanese food score, energy density, fat energy content, and saturated fatty acid score were calculated. These indices were compared for sex, age group and body mass index.

Results

Indices reflecting food interest or fat preference were significantly higher in boys than girls both in the 7–9‐ and 10–12‐year‐old age groups. Positive correlations were found between food interest score and energy density, fat energy content, and saturated fatty acid score.

Conclusions

Using the picture choice method, definite gender differences in food preference were identified in early elementary school children. This information could be useful for dietary therapy in childhood obesity.
Need to Focus Beyond the Medical Causes: a Systematic Review of the Social Factors Affecting Neonatal Deaths
Authors: Upadhyay Ravi Prakash , Krishnan Anand , Rai Sanjay K. , Chinnakali Palanivel , Odukoya Oluwakemi
Published: December 2013

Background

Reducing the global total of 3.3 million neonatal deaths is crucial to meeting the fourth Millennium Development Goal. Until recently, attention has been on the medical causes of the neonatal deaths, while the social factors contextualising these deaths have largely remained unaddressed. The current review aimed to quantify the role of these factors in neonatal deaths.

Methods

A systematic search was performed through PubMed, Google scholar, Cochrane library, Medline, IndMed, Embase, World Health Organization and Biomed central databases. Studies published from 1995 to 2011 were included. Random effects meta‐analysis was performed to derive at an estimate of the burden of delays, as defined by the ‘three delays model’ by Thadeus and Maine.

Results

A total of 17 studies were reviewed. The majority of them (n = 10) were from the African continent. Level 3 delay, i.e. delay in receiving appropriate treatment upon reaching a health facility (38.7%, 95% CI, 21.7%–57.3%) and delay in deciding to seek care for the illness (Level 1 delay) (28%, 95% CI, 16%–43%) were the major contributors to neonatal deaths. Level 2 delay, i.e. delay in reaching a health facility (18.3%, 95% CI, 2.6–43.8%) contributed least to the neonatal deaths.

Conclusion

Creating awareness among caregivers regarding early recognition and treatment seeking for neonatal illness along with improving the quality of neonatal care provided at the health facilities is essential to reduce neonatal mortality.
Race/Ethnicity, Educational Attainment, and Pregnancy Complications in New York City Women with Pre‐existing Diabetes
Authors: James‐Todd Tamarra , Janevic Teresa , Brown Florence M. , Savitz David A.
Published: December 2013

Background

More women are entering pregnancy with pre‐existing diabetes. Disease severity, glycaemic control, and predictors of pregnancy complications may differ by race/ethnicity or educational attainment, leading to differences in adverse pregnancy outcomes.

Methods

We used linked New York City hospital record and birth certificate data for 6291 singleton births among women with pre‐existing diabetes between 1995 and 2003. We defined maternal race/ethnicity as non‐Hispanic white, non‐Hispanic black, Hispanic, South Asian, and East Asian, and education level as <12, 12, and >12 years. Our outcomes were pre‐eclampsia, preterm birth (PTB) (<37 weeks gestation and categorised as spontaneous or medically indicated), as well as small‐for‐gestational age (SGA) and large‐for‐gestational age (LGA). Using multivariable binomial regression, we estimated the risk ratios for pre‐eclampsia, SGA, and LGA. We used multivariable multinomial regression to estimate odds ratios (OR) for PTB.

Results

Compared with non‐Hispanic white women with pre‐existing diabetes, non‐Hispanic black and Hispanic women with pre‐existing diabetes had a 1.50‐fold increased risk of pre‐eclampsia compared with non‐Hispanic whites with pre‐existing diabetes, after full adjustment. Non‐Hispanic black and Hispanic women with pre‐existing diabetes had adjusted ORs of 1.72 [adj. 95% confidence interval (CI) 1.38, 2.15] and 1.65 [adj.95% CI 1.32, 2.05], respectively, for medically indicated PTB. South Asian women with pre‐existing diabetes had the highest risk for having an SGA infant [adj. OR: 2.29; adj. 95% CI 1.73, 3.03]. East Asian ethnicity was not associated with these pregnancy complications.

Conclusions

Non‐Hispanic black, Hispanic, and South Asian women with pre‐existing diabetes may benefit from targeted interventions to improve pregnancy outcomes.
Risk Factors for High and Low Placental Weight
Authors: McNamara Helen , Hutcheon Jennifer A. , Platt Robert W. , Benjamin Alice , Kramer Michael S.
Published: December 2013

Background

Placental weight is an independent predictor of adverse perinatal outcome. However, risk factors for high and low placental weight are poorly understood. The objective of this study was to identify maternal, placental, and umbilical cord determinants of placental weight, before and after accounting for birthweight.

Methods

This cohort study of 87 600 singleton births at the Royal Victoria Hospital in Montreal, Canada assessed the relationship between maternal, placental, and umbilical cord characteristics and placental weight (standardised for sex and gestational age). We separately examined risk factors for high (z‐score >+1) and low (z‐score <−1) placental weight. Multivariable logistic regression was used to study associations after adjusting for confounders and further adjusting for birthweight.

Results

Chronic hypertension was associated with low placental weight {relative risk (RR) 2.1 [95% confidence interval (CI) 1.8, 2.4] and 1.8 [95% CI 1.5, 2.1] before and after accounting for birthweight}, while pre‐eclampsia was associated with low placenta weight before, but not after adjustment for birthweight. Anaemia and gestational diabetes were linked with high placental weight (RRs 1.2–1.4, respectively) before and after adjustment for birthweight, while smoking was linked with high placental weight only after adjustment for birthweight (RR 1.4 [95% CI 1.3, 1.5]). Placental and cord determinants of high placental weight included chorioamnionitis, chorangioma/chorangiosis, circumvallate placenta, marginal cord insertion, and other cord abnormalities.

Conclusions

The broad range of risk factors for high placental weight suggests multiple aetiologic pathways. Future work should seek to understand the pathways by which the placenta adapts to unfavourable intrauterine conditions, which may provide insights into potential therapies.
Generalized Mann–Whitney Type Tests for Microarray Experiments
Authors: Fischer Daniel , Oja Hannu , Schleutker Johanna , Sen Pranab K. , Wahlfors Tiina
Published: December 2013

New statistical procedures are introduced to analyse typical microRNA expression data sets. For each separate microRNA expression, the null hypothesis to be tested is that there is no difference between the distributions of the expression in different groups. The test statistics are then constructed having certain type of alternatives in mind. To avoid strong (parametric) distributional assumptions, the alternatives are formulated using probabilities of different orders of pairs or triples of observations coming from different groups, and the test statistics are then constructed using corresponding several‐sample U‐statistics, natural estimates of these probabilities. Classical several‐sample rank test statistics, such as the Kruskal–Wallis and Jonckheere–Terpstra tests, are special cases in our approach. Also, as the number of variables (microRNAs) is huge, we confront a serious simultaneous testing problem. Different approaches to control the family‐wise error rate or the false discovery rate are shortly discussed, and it is shown how the Chen–Stein theorem can be used to show that family‐wise error rate can be controlled for cluster‐dependent microRNAs under weak assumptions. The theory is illustrated with an analysis of real data, a microRNA expression data set on Finnish (aggressive and non‐aggressive) prostate cancer patients and their controls.
Generation of Segmented Triangular Meshes From CT Images Based on Centroidal Voronoi Tessellation and the Graph Cut Method
Authors: Yang Caiyun , Ohtake Yutaka , Moriguchi Masaki , Suzuki Hiromasa
Published: December 2013

Mesh generation from X-ray computed tomography (CT) images of mechanical parts is an important consideration in industrial application, and boundary surface meshes in multimaterial parts can be extracted by generating segmented meshes from segmented images. In this paper, the authors outline a new approach for achieving segmented mesh generation. The image is first subjected to centroidal Voronoi tessellation and Delaunay tessellation steered by a density map to create a triangular mesh while maintaining discontinuities between materials. Given an input domain and a number of initial sites, the energy function is minimized automatically by iteratively updating the Voronoi tessellation and relocating sites to produce optimized domain discretization and form the mesh. Thus, the mesh in question is effectively and quickly segmented into different parts via this new graph cut method. The proposed approach is considered more efficient because there are fewer triangles than pixels, which reduces computation time and memory usage.
Development and Experimental Validation of A Handheld Noninvasive Sensor for the Measurement of Compartment Pressures
Authors: Flegel C. , Singal K. , Rajamani R. , Odland R.
Published: December 2013

Compartment syndrome is a major concern in cases of extremity trauma, which occur in over 70% of military combat casualty. Without treatment, compartment syndrome can lead to paralysis, loss of limb, or death. This paper focuses on the development of a handheld sensor that can be used for the noninvasive diagnosis of compartment syndrome. Analytical development of the sensing principle is first presented in which a relation is obtained between the pressure in a fluid compartment and the stiffness experienced by a handheld probe pushing on the compartment. Then a handheld sensor that can measure stiffness of an object without requiring the use of any inertial reference is presented. The handheld sensor consists of an array of three miniature force-sensing spring loaded pistons placed together on a probe. The center spring is chosen to be significantly stiffer than the side springs. The ratio of forces between the stiff and soft springs is proportional to the stiffness of the soft object against which the probe is pushed. Small millimeter-sized magnets on the pistons and magnetic field measurement chips are used to measure the forces in the individual pistons. Experimental results are presented using both an in vitro pneumatic test rig and a compliant agarose gel chamber that replicates a fluid pressure compartment. The sensor is shown to measure pressure accurately with a resolution of 0.1 psi over the range 0.75–2.5 psi. The developed sensor has the potential to be useful for convenient handheld diagnosis of compartment syndrome in traumatic extremity injuries.
Direct Numerical Simulation of Forced Convective Heat Transfer From a Heated Rotating Sphere in Laminar Flows
Authors: Feng Zhi-Gang
Published: December 2013

The laminar forced convection of a heated rotating sphere in air has been studied using a three-dimensional immersed boundary based direct numerical simulation method. A regular Eulerian grid is used to solve the modified momentum and energy equations for the entire flow region simultaneously. In the region that is occupied by the rotating sphere, a moving Lagrangian grid is used, which tracks the rotational motion of the particle. A force density function or an energy density function is introduced to represent the momentum interaction or thermal interaction between the sphere and fluid. This numerical method is validated by comparing simulation results with analytical solutions of heat diffusion problem and other published experimental data. The flow structures and the mean Nusselt numbers for flow Reynolds number ranging from 0 to 1000 are obtained. We compared our simulation results of the mean Nusselt numbers with the correlations from the literature and found a good agreement for flow Reynolds number greater than 500; however, a significant discrepancy arises at flow Reynolds number below 500. This leads us to develop a new equation that correlates the mean Nusselt number of a heated rotating sphere for flows of 0≤Re≤500.
In-Plane Forces Prediction and Analysis in High-Speed Conditions on a Contra-Rotating Open Rotor
Authors: François Benjamin , Laban Martin , Costes Michel , Dufour Guillaume , Boussuge Jean-François
Published: December 2013

Due to the growing interest from engine and aircraft manufacturers for contra-rotating open rotors (CROR), much effort is presently devoted to the development of reliable computational fluid dynamics (CFD) methodologies for the prediction of performance, aerodynamic loads, and acoustics. Forces transverse to the rotation axis of the propellers, commonly called in-plane forces (or sometimes 1P forces), are a major concern for the structural sizing of the aircraft and for vibrations. In-plane forces impact strongly the stability and the balancing of the aircraft and, consequently, the horizontal tail plane (HTP) and the vertical tail plane (VTP) sizing. Also, in-plane forces can initiate a flutter phenomenon on the blades or on the whole engine system. Finally, these forces are unsteady and may lead to vibrations on the whole aircraft, which may degrade the comfort of the passengers and lead to structural fatigue. These forces can be predicted by numerical methods and wind tunnel measurements. However, a reliable estimation of in-plane forces requires validated prediction approaches. To reach this objective, comparisons between several numerical methods and wind tunnel data campaigns are necessary. The primary objective of the paper is to provide a physical analysis of the aerodynamics of in-plane forces for a CROR in high speed at nonzero angle of attack using unsteady simulations. Confidence in the numerical results is built through a code-to-code comparison, which is a first step in the verification process of in-plane forces prediction. Thus, two computational processes for unsteady Reynolds-averaged Navier–Stokes (URANS) simulations of an isolated open rotor at nonzero angle of attack are compared: computational strategy, open rotor meshing, aerodynamic results (rotor forces, blades thrust, and pressure distributions). In a second step, the paper focuses on the understanding of the key aerodynamic mechanisms behind the physics of in-plane forces. For the front rotor, two effects are predominant: the first is due to the orientation of the freestream velocity, and the second is due to the distribution of the induced velocity. For the rear rotor, the freestream velocity effect is reduced but is still dominant. The swirl generated by the front rotor also plays a major role in the modulus and the direction of the in-plane force. Finally, aerodynamic interactions are found to have a minor effect.
Battery Thermal Management for Hybrid Electric Vehicles Using a Phase-Change Material Cold Plate
Authors: Barsotti Domenic L. , Hyatt W. Townsend , Compere Marc D. , Boetcher Sandra K. S.
Published: December 2013

A novel liquid-cooled (50-50 ethylene glycol-water mixture) composite cold plate made of phase-change material (PCM) is proposed as a thermal management solution for energy storage systems (ESS) in hybrid-electric vehicles (HEV). The composite cold plate is lighter than a traditional aluminum cold plate and able to absorb high heat flux spikes. Furthermore, the pump operation time is reduced. The goal of the present study is to evaluate the effectiveness of a preliminary PCM cold plate subjected to constant heat flux. The inlet temperature of the working fluid is parametrically varied and results include PCM temperatures and pump operation times.
Fluid Flow and Capillary Limit in Heat Pipe Thermal Ground Planes
Authors: Ababneh Mohammed T. , Gerner Frank M.
Published: December 2013

This work shows the solution of the fluid flow and the capillary limit in heat pipe thermal ground planes after solving the temperature field. In addition, the effect of wall shear stress and the interfacial shear stress in the liquid pressure of the TGP is studied. In order to obtain more accurate results it is necessary to solve the velocity and thermal fields in both the liquid saturated wick and the vapor. It is also important to account for the mass, momentum and energy balances at the interface between the vapor and liquid. Previous work demonstrated that for the TGP’s which utilize water as the working fluid, the Jacob number is very small. A consequence of this is that convection of liquid with the wick is much smaller than conduction and the temperature may be solved independently of the velocity field. These solutions were presented in previous work. A key feature of the thermal model is that it relies on empirical interfacial heat transfer coefficient data to very accurately model the interfacial energy balance at the vapor-liquid saturated wick interface. One important result uses a solution for the evaporation and condensation rates and hence normal velocities at the interface. The results show that for all of the TGP’s lengths, the ratio between the pressure drop in the vapor and the pressure drop in the liquid is close to zero. Therefore, the pressure drop in the liquid will determine the capillary limit in the TGP.
Non-Dimensional Analysis for the Fluid Flow in the Flat Heat Pipes
Authors: Ababneh Mohammed T. , Gerner Frank M.
Published: December 2013

Flat heat pipes (heat spreaders) are similar to cylindrical heat pipes. But they have received significant attention recently because of their advantages over conventional cylindrical heat pipes with regard to their large surface area, isothermal heat delivery, geometry fit. For example, Thermal Ground Planes (TGPs) are flat, thin (less than 3 mm thick) heat pipes which utilize phase change cooling. The goal is to use TGP’s as universal heat spreaders in microelectronic cooling applications. These TGPs will act as a new generation of high-performance, integrated systems to work at a high power density without difficulties from temperature gradients, increased weight, or extra complexity. In addition to being able to dissipate high thermal powers, they have very high effective thermal conductivities and can operate in high adverse gravitational fields due to nano-porous wicks.

This work shows the effect of vapor pressure, wall shear stress and the interfacial shear stress in the liquid pressure of the flat heat pipes and a comparison with CFD results. Also, this paper offers a design for flat heat pipe charts that avoids the effects of vapor pressure, wall shear stress and the wick-vapor interface to the liquid pressure for most well-known working fluids.
Tritium Production and Permeation in High-Temperature Reactor Systems
Authors: Sabharwall Piyush , Schmutz Hans , Stoots Carl , Griffith George
Published: December 2013

Tritium (H13) is a radioactive isotope of hydrogen formed by ternary fission events (rare emissions of three nuclides rather than two during a fission) and neutron absorption (and subsequent decay) of predecessor radionuclides, particularly 6Li and 7Li. Also in fusion, the concept of breeding tritium during the fusion reaction is of significance for the future needs of a large-scale fusion power plant. Tritium is of special interest among the fission products created in next-generation nuclear reactors such as gas cooled reactors and molten salt reactors, because of the large quantities produced when compared with conventional light-water reactors (LWR) and the higher temperatures of operation for these systems enhances permeation. To prevent the tritium contamination of proposed reactor buildings and surrounding sites, this paper examines the root causes and potential solutions for mitigation of permeation of this radionuclide, including materials selection and inert gas sparging. A model is presented that can be used to predict permeation rates of hydrogen through metallic alloys at temperatures from 450–750°C. Results of the diffusion model are presented along with mitigation strategies for tritium permeation.
ASME Material Challenges for Advance Reactor Concepts
Authors: Siahpush Ali , Sabharwall Piyush
Published: December 2013

This study presents the material challenges associated with Advanced Reactor Concepts (ARC) such as the Advanced High Temperature Reactor (AHTR). ARCs are the next generation concepts focusing on power production and providing thermal energy for industrial applications. The efficient transfer of energy for industrial applications depends on the ability to incorporate cost-effective heat exchangers between the nuclear heat transport system and industrial process heat transport system.

The heat exchanger required for AHTR is subjected to a unique set of conditions that introduce several design challenges not encountered in standard heat exchangers. The corrosive molten salts, especially at higher temperatures, require materials throughout the system to avoid corrosion, and adverse high-temperature effects, such as creep. Given the very high steam generator pressure of the supercritical steam cycle, it is anticipated that water tube and molten salt shell steam generators heat exchanger will be used.

In this paper, the American Society of Mechanical Engineers (ASME) Section III and Section VIII requirements (acceptance criteria) are discussed. Also, the ASME material acceptance criteria (ASME Section II, Part D) for high temperature environments are presented. Finally, lack of ASME acceptance criteria for thermal design and analysis are discussed with potential benefit.
An Experimental Study of a Multi-Device Jet Impingement Cooler With Phase Change Using HFE-7100
Authors: Joshi Shailesh N. , Rau Matthew J. , Dede Ercan M. , Garimella Suresh V.
Published: December 2013

Jet impingement cooling with phase change has shown the potential to meet the increased cooling capacity demands of high-power-density (of order 100 W/cm2) automotive electronics components. In addition to improved heat transfer, phase change cooling has the potential benefit of providing a relatively isothermal cooling surface. In the present study, two-phase jet impingement cooling of multiple electronic devices is investigated, where the fluorinated dielectric fluid HFE-7100 is used as the working fluid. Four different types of jet arrays, namely, a single round jet with orifice diameter of 3.75 mm, and three different 5 × 5 arrays of round jets with orifice diameters of 0.5 mm, 0.6 mm and 0.75 mm, were tested and compared for both heat transfer and pressure drop. The experimental Reynolds number at the orifice ranged from 1860 to 9300. The results show that for the same orifice pressure drop, the single jet reached CHF at approximately 60 W/cm2, while the 5 × 5 array (d = 0.75 mm) safely reached heat fluxes exceeding 65 W/cm2 without reaching CHF. Additionally, the experimental results show that the multi-device cooler design causes an unintended rise in pressure inside the test section and a subsequent increase in sub-cooling from 10 K to 23.3 K.
Energy Conservation Measures of a Primary Data Center on an Academic Campus
Authors: Choo Kyosung , Galante Renan Manozzo , Ohadi Michael
Published: December 2013

Energy Conservation Measures (ECMs) of the primary data center at the University of Maryland are developed. Measurement and simulation are performed to validate the developed ECMs. Three ECMs — 1) Increase in the return temperature at Computer Room Air Conditionings (CRACs) 2) Cold aisle containment 3) Elimination of unnecessary CRACs — are suggested to reduce energy consumption by optimizing the thermo-fluid flow in the data center. Power savings of 12.7 kW – 17.4 kW and 14.1 kW are obtained by increasing the return air temperatures at the CRACs and performing the cold aisle containment, respectively. In addition, a power saving of 11.2 kW is obtained by turning off CRACs 3 and 8 which have an adverse effect on the data center cooling.
Investigation of Microboiler for Discarded Thermal Scavenging
Authors: Thapa S. , Fang J. , Wood D. , Weiss L.
Published: December 2013

This paper presents detailed fabrication and operational characterization of a MEMS based microboiler designed to scavenge waste thermal energy from sources like transportation or industry. Microboiler operation is based on capillary action that drives the working fluid from surrounding reservoirs to the surface that is heated by the waste thermal energy. As a result of phase change from liquid to vapor, pressure is created inside the enclosed central steamdome. This pressurized vapor can be made available to another MEMS device (PZT membranes, thermoelectric, etc.) to produce useful power output. In contrast to previous work, the new miniature microboiler design has undergone several modifications that improve operating efficiency. Capillary channels that were designed in linear fashion have been upgraded to a radial layout. This modification facilitated boiler enhancements in capillary flow, operating pressure, and rate of mass transfer. Capillary channels are formed from the silicon substrate with 50 μm widths and 100 μm depths. Power inputs of 2W, 3W and 4W are utilized to characterize performance. Maximum energy absorption via phase change of working fluid was 1.6 mW given a source temperature of 128 °C. The maximum steady state operating pressure achieved during testing was 3.65 kPa.
Numerical Analysis of Composite Fouling in Corrugated Plate Heat Exchanger
Authors: Li Wei , Li Hongxia
Published: December 2013

This paper provides a numerical analysis on precipitation and particulate fouling in a corrugated plate heat exchanger. This analysis started from the mass balance fouling model, and Realizable κ-ε model with non-equilibrium wall functions is used in the 3D numerical simulation considering the realistic geometries of the flow channel to obtained Nusselt number and wall shear stress, while Von-Karman analogy is used to obtain mass transfer coefficient. The numerical analysis is verified by experimental study. The predicted influence of fluid velocity in fouling resistance is compatible with experimental data that it can help to optimize the design of plate heat exchangers. The investigation significantly simplifies the fouling analysis of complex flow fields and can be used to assess the fouling potential of corrugated plate heat exchangers.
Numerical Convection Heat Transfer in Metal Foam Using Unit Cell Geometry
Authors: Suleiman Ahmed S. , Dukhan Nihad
Published: December 2013

Open-cell metal foam is a class of modern porous media that possesses high thermal conductivity, large accessible surface area per unit volume and high porosities (often greater than 90%). The high porosity means very low weight. The internal structure of the foam is web-like. Internal flow inside the foam is complex and includes flow reversal, destruction of boundary layers and vigorous mixing. All of these attributes make metal foam a very attractive heat transfer core for many applications. The rather complex and intrinsically random architecture of the foam is virtually impossible to capture exactly. In this paper, we present a unit cell geometrical model that was used to represent the foam structure for numerical analysis purposes. In particular, the unit cell is used to numerically study forced convection heat transfer between aluminum foam and air. The Navier-Stokes and the governing energy equation are solved directly and the temperature fields are obtained using COMSOL. The details of the modeling process are given in this paper. The results are encouraging and lend confidence to the modeling approach, which paves the way for other investigations of the foam, as well as optimization work based on the structure of the foam.
Improved Correlations for Counting the Effect of Natural Convection on Laminar Flow of Nanofluids
Authors: Guo Si-pu , Feng Zhao-zan , Fang Ze-cong , Li Wei , Xu Jin-liang , Jiang Pei-xue
Published: December 2013

Nanofluids are colloidal suspensions of nano-scale particles in water, or other base fluids. In this paper, the effect of natural convection on laminar flow of nanofluids in a horizontal tube has been addressed. The obtained experimental data could not be reconciled with existing correlations over a wide range of Prandtl number under laminar mixed convection. Three improved correlations have been derived by using single-phase fluid approach. These correlations fit our data to within ± 10 % and also agree with the data in literature quite well. Such results verify that nanofluids can be treated as a homogeneous mixture with effective thermophysical properties. Utimately, the new correlations have grasped the essence of natural convection and can reduce to both normal forced convection and pure natural convection equations at limiting cases.
Numerical Study of Internal Fire Whirls in a Kitchen With Ceiling Vents
Authors: Chow W. K. , Cai N. , Gao Y.
Published: December 2013

The characteristics of flame rotation induced by a fire at the top of kitchen stove were studied numerically with Computational Fluid Dynamics (CFD). Four cases with different locations of fire sources and vents were set up; simulations of swirling air flow and temperature distributions in the kitchen room were carried out. Ventilation by ceiling vents was identified as the necessary condition for internal fire whirl. Recommendations on the design of kitchen ventilation system were made.
Technologies for Upgrading Light Water Reactor Outlet Temperature
Authors: Wendt Daniel S. , Sabharwall Piyush , Utgikar Vivek
Published: December 2013

Nuclear energy could potentially be utilized in hybrid energy systems to produce synthetic fuels and feedstocks from indigenous carbon sources such as coal and biomass. First generation nuclear hybrid energy system (NHES) technology will most likely be based on conventional light water reactors (LWRs). However, these LWRs provide thermal energy at temperatures of approximately 300°C, while the desired temperatures for many chemical processes are much higher. In order to realize the benefits of nuclear hybrid energy systems with the current LWR reactor fleets, selection and development of a complimentary temperature upgrading technology is necessary. This paper provides an initial assessment of technologies that may be well suited toward LWR outlet temperature upgrading for powering elevated temperature industrial and chemical processes during periods of off-peak power demand.

Chemical heat transformers (CHTs) are a technology with the potential to meet LWR temperature upgrading requirements for NHESs. CHTs utilize chemical heat of reaction to change the temperature at which selected heat sources supply or consume thermal energy. CHTs could directly utilize LWR heat output without intermediate mechanical or electrical power conversion operations and the associated thermodynamic losses. CHT thermal characteristics are determined by selection of the chemical working pair and operating conditions. This paper discusses the chemical working pairs applicable to LWR outlet temperature upgrading and the CHT operating conditions required for providing process heat in NHES applications.
A 3-D Numerical Analysis of the Effect of Fin Pattern on the Thermo-Hydarulic Performance of Plate Heat Exchangers
Authors: Li Kun-Hao , Wang Chi-Chuan
Published: December 2013

This study numerically examines some commercially available plate patterns of plate heat exchangers using a 3-D CFD simulation. Detailed flow distribution and heat transfer characteristics subject to three different plate patterns are examined in this study. The plate pattern include GC26 and NT10 (double chevron) and SW26. The effective surface area of the associated plate patterns are 0.8671, 0.6808, and 0.6721 m2, respectively. The corresponding chevron angle are 33°, 64° (double chevron) and 61°, repectively. The calculated results show that the heat transfer efficient for NT10 is higher than that of GC26 by approximately 6.35% and is higher than SW26 by 10.3%. The results indicate that the heat transfer characteristics for the double chevron plate outperform that of the single chevron plate. On the other hand, the pressure drop is also increased with the double chevron as well as chevron angle. However, it is found that the double chevron design provides a better heat transfer capability subject to identical pressure drop.
Steady-State Performance of a Prototype (200 cfm) Liquid-to-Air Membrane Energy Exchanger (LAMEE) Under Summer and Winter Test Conditions
Authors: Ghadiri Moghaddam Davood , Mahmood Gazi , Ge Gaoming , Bolster John , Besant Robert W. , Simonson Carey J.
Published: December 2013

Liquid-to-air membrane energy exchangers (LAMEEs) are a new generation of energy exchangers in air-conditioning systems to transfer both heat and moisture. In this paper, the performance of a 200 cfm LAMEE is numerically and experimentally investigated under summer and winter test conditions when Lithium Chloride (LiCl) is used as a salt solution in the exchanger. The results show that the LAMEE has almost the same total effectiveness at summer and winter conditions, but the latent effectiveness of the LAMEE is higher at the summer conditions. Also, the agreement between the experimental and numerical results is acceptable for all the tests, and they are within their uncertainty ranges except for the latent effectiveness of the LAMEE tested under winter test conditions.
Flow Boiling Heat Transfer and Two-Phase Flow Instability of Nanofluids in a Minichannel
Authors: Yu Leyuan , Liu Dong
Published: December 2013

Recent studies of single-phase convective heat transfer of nanofluids reveal that, unlike the promising hypohesis in the early works, there is no significant improvement in the overall thermal performance of nanofluids over that of the base fluids when both heat transfer and hydrodynamic characteristics are considered. Meanwhile, very few studies have been devoted to investigating two-phase heat transfer of nanofluids, and it remains inconclusive whether the same pessimistic outlook should be expected. In this work, an experimental study of forced convective flow boiling and two-phase flow was conducted for Al2O3-water nanofluids through a minichannel. General flow boiling heat transfer characteristics were measured, and the effects of nanofluids on the onset of nucleate boiling (ONB) were studied. Two-phase flow instabilities were also explored with an emphasis on the transition boundaries of onset of flow instabilities (OFI). It was found that the presence of nanoparticles delays ONB and suppresses OFI, and the extent is correlated to the nanoparticle volume concentration. These effects were attributed to the change of surface wettability and the thinning of thermal boundary layer in the nanofluid flow. Additionally, it was observed that the pressure-drop type flow instability prevails in nanofluid two-phase flow, however, the oscillation amplitudes of the pressure, temperature and mass flux measurements are reduced.
Effect of Uncertainty in Blowing Ratio on Film Cooling Effectiveness
Authors: Babaee Hessam , Wan Xiaoliang , Acharya Sumanta
Published: December 2013

In this study the effect of randomness of blowing ratio on film cooling performance is investigated by combining direct numerical simulations with a stochastic collocation approach. The geometry includes a 35-degree inclined jet with a plenum attached to it. The blowing ratio variations are assumed to have a truncated Gaussian distribution with mean of 0.3 and the standard variation of approximately 0.1. The parametric space is discretized using Multi-Element general Polynomial Chaos (ME-gPC) with five elements where general polynomial chaos of order 3 is used in each element. A fast convergence of the polynomial expansion in the random space was observed. Direct numerical simulations were carried out using spectral element method to sample the governing equations in space and time. The probability density function of the film cooling effectiveness was obtained and the standard deviation of the adiabatic film cooling effectiveness on the blade surface was calculated. A maximum standard deviation of 15% was observed in the region within a four-jet-diameter distance downstream of the exit hole. The spatially-averaged adiabatic film cooling effectiveness was 0.23 ± 0.02. The calculation of all the statistical properties were carried out as off-line post-processing. Overall the computational strategy is shown to be very effective with the total computational cost being equivalent to solving twenty independent direct numerical simulations that are performed concurrently.
A Numerical Study of Natural Convective Heat Transfer From Isothermal High Aspect Ratio Rectangular Cylinders
Authors: Oosthuizen Patrick H.
Published: December 2013

Natural convective heat transfer from isothermal rectangular cylinders which have an exposed upper surface has been numerically studied. The cylinders considered have high aspect ratios, i.e., have high width-to-depth ratios, and are relatively short, i.e., have a “height” that is of the same order of magnitude as their width. The cylinders considered are mounted on a plane adiabatic base, the cylinders being normal to the plane base with the cylinders pointing either vertically upwards or vertically downwards. One of the main aims of the present work was to numerically determine how the depth-to-width ratio of the rectangular cylinder influences the mean heat transfer rate from the cylinder when this depth-to-width ratio is large. The flow has also been assumed to be steady and laminar and it has been assumed that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces, this having been treated by using the Boussinesq approach. The solution has been obtained by numerically solving the governing equations using the commercial CFD solver, ANSYS FLUENT©. The solution is dependent on the Rayleigh number, the ratio of the width to the height of the heated cylinder, the ratio of the width to the depth of the heated cylinder, the Prandtl number, Pr, and on whether the cylinder is pointing vertically upwards or vertically downwards. Because of the applications that motivated this study, results have only been obtained for a Prandtl number of 0.74, i.e., effectively the value for air. A range of the other governing parameters has been considered and the effects of these governing parameters on the Nusselt number variation have been examined.