bluuebunny/crossref_metadata_2025 huggingface dataset:
Widespread Pressure Pain Hypersensitivity Is Similar in Women With Frequent Episodic and Chronic Tension‐Type Headache: A Blinded Case–Control Study
Authors: Palacios Ceña María , Castaldo Matteo , Kelun Wang  , Torelli Paola , Pillastrini Paolo , Fernández‐de‐las‐Peñas César , Arendt‐Nielsen Lars
Published: November 2016

Objective

To investigate differences in widespread pressure pain hyperalgesia in the trigemino‐cervical and extra‐trigeminal (distant pain‐free) regions in women with frequent episodic (FETTH) and chronic (CTTH) tension‐type headache.

Background

It seems that people with tension‐type headache exhibit central sensitization. No study has investigated differences between FETTH and CTTH in terms of widespread pressure pain hypersensitivity.

Methods

Forty‐three women with FETTH, 42 with CTTH, and 45 women without headache diagnosis were recruited. Pressure pain thresholds (PPTs) were bilaterally assessed over trigeminal area (ie, temporalis muscle), extra‐trigeminal (ie, C5/C6 zygapophyseal joint), and two distant points (ie, second metacarpal and tibialis anterior muscle) by a blinded assessor. Clinical features of the headache were collected with a 4‐week headache diary. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scale (HADS).

Results

The ANCOVA revealed that PPTs were significantly decreased bilaterally over trigeminal (mean differences ranging from 97.5 to 101.5 kPa), extra‐trigeminal (from 94.3 to 114.5 kPa), and distant points (from 99.4 to 208.6 kPa) in both FETTH and CTTH groups compared with controls (all, P < .001). No differences between FETTH and CTTH were observed (all points, P > .217). Anxiety (all, P > .803) or depression (P > .206) did not influence pressure pain hyperalgesia. No associations between widespread pressure hypersensitivity and headache features were observed (all, P > .110).

Conclusions

Current results suggest the presence of similar local and widespread pressure hyperalgesia, not associated with anxiety or depression, in women with FETTH and CTTH supporting that localized and central manifestations are involved in both the episodic and chronic forms of tension‐type headache.
A multivariate study of over‐indebtedness' causes and consequences
Authors: Gutiérrez‐Nieto Begoña , Serrano‐Cinca Carlos , de la CuestaߚGonzález Marta
Published: November 2016

This paper proposes a comprehensive explanatory model to explain both causes and consequences of over‐indebtedness. It presents as causes some borrower aspects, such as propensity to indebtedness and low financial literacy. Other causes are borrower circumstances: adverse external shocks, borrower internal problems and financial institutions' pressure. The model incorporates consequences on the borrower, the lender and the society. The model has been tested with a survey filled in by experts and over‐indebted individuals. Results have been analysed using multivariate techniques, including canonical correlations. There are differences in the opinions of experts and individuals: the latter blame external shocks or financial institutions' pressure, while the former find relevant factors the financial illiteracy or the tendency to imitate others. Experts and individuals agree on the consequences: poverty growth in the society and declining borrower's welfare. The paper concludes with the need to improve financial literacy, especially in the risks involved in over‐indebtedness.
Understanding bottled water consumption in a high‐poverty context: empirical evidence from a small town in Guatemala
Authors: Vásquez William F.
Published: November 2016

This research investigated the determinants of bottled water consumption using household survey data from a small, poor town in Guatemala. Hurdle (two‐part) models were estimated to account for 73.3% of sampled households that did not consume bottled water. Findings indicated that the vast majority of respondents perceived minimal health risks from drinking bottled water. In contrast, few respondents (3.2%) believed that tap water is totally safe to drink. Estimation results indicated that bottled water consumption was positively associated to health risk perceptions, household income, education and market access. Household size had a negative effect on the likelihood of consuming bottled water. However, once the household had decided to consume bottled water, its consumption increased with each additional household member.
Patient, family, nurse perspectives on Chinese elders' quality of life
Authors: Wang W. , McDonald T.
Published: November 2016

Background

Families and nurses are important care‐providers and proxies of older people. Their ability to assess the quality of life of elders in ways that align with how older people assess themselves has policy implications for allocating services and resources to older persons.

Aim

To investigate the alignment of perspectives of the quality of life held by older people, their families and nurses in China.

Methods

Employing a survey design using concurrent EQ‐5D‐3L and WHOQOL‐BREF surveys, responses from 72 matched stakeholder groups were compared and agreement tested using weighted kappa/one‐way random intra‐class correlations and paired Student's t‐test.

Results

On the more observable dimensions families and nurses were in close agreement with the older person in relation to quality of life reports. However, in the more subjective domains, family and especially nurses tended to estimate that the older person's suffering as more severe than they themselves thought.

Conclusion

The perspectives of older patients and their family are more closely aligned regarding the older person's quality of life than that of nurses caring for them, a finding inconsistent with international research.

Implication for nursing and health policy

The evidence suggests that nursing work assignment processes could influence the accuracy of nurses' perceptions of their patient's quality of life.
Enhanced ferroelectric properties and thermal stability of Mn‐doped 0.96(Bi0.5 Na0.5)TiO3‐0.04BiAlO3 ceramics
Authors: Peng Ping , Nie Hengchang , Liu Zhen , Ren Weijun , Cao Fei , Wang Genshui , Dong Xianlin
Published: November 2016

(Bi0.5Na0.5)TiO3–BiAlO3 lead‐free materials exhibit excellent ferroelectric properties, but its depolarization temperature is relatively low which is the major obstacle limiting the material's practical application. In this study, the effects of Manganese (Mn) modification on the microstructure, ferroelectric properties and depolarization behavior of 0.96(Bi0.5Na0.5)(Ti1−xMnx)O3–0.04BiAlO3 ceramics were investigated. It was found that the average grain size was enlarged and ferroelectric properties were enhanced with small Mn addition, meanwhile the tangent loss decreased. The remnant polarization (Pr) of the samples reached an optimal value (~41 μC/cm2) as Mn content increased up to 0.7 mol%, whereas further addition resulted in the decrease in Pr. Moreover, appropriate Mn addition (x=0.7%) can improve the depolarization temperature from 140°C to 161°C determined from thermally stimulated depolarization currents measurement.
Multiple births by a captive swellshark Cephaloscyllium ventriosum via facultative parthenogenesis
Authors: Feldheim K. A. , Clews A. , Henningsen A. , Todorov L. , McDermott C. , Meyers M. , Bradley J. , Pulver A. , Anderson E. , Marshall A.
Published: November 2016

Using a novel set of 12 microsatellites, a captive, adult female swellshark Cephaloscyllium ventriosum that produced five pups via parthenogenesis is described; naturally occurring parthenogenesis has been observed in every vertebrate class with the exception of mammals. As demonstrated in this study, a captive environment is ideal for long‐term monitoring of animals under controlled conditions, and easily allows the detection of particular facets of their biology.
Long non‐coding ribonucleic acid zinc finger antisense 1 promotes the progression of colonic cancer by modulating ZEB1 expression
Authors: Fang Changyi , Zan Jianbao , Yue Ben , Liu Chenchen , He Chenglong , Yan Dongwang
Published: November 2016

Background and Aim

Long non‐coding RNA zinc finger antisense 1 (ZFAS1) is frequently amplified in hepatocellular carcinoma and promotes metastasis by increasing zinc finger E‐box binding homeobox 1 (ZEB1), which can potentiate the progression of epithelial‐to‐mesenchymal transition (EMT). However, the expression pattern and role of ZFAS1 in colonic cancer remains unknown. The present study aimed to investigate the role of ZFAS1 and its clinical significance in colonic cancer.

Methods

Paired clinical colonic cancer tissue samples and clinicopathologic characteristics of 73 patients were analyzed. Quantitative real‐time polymerase chain reaction analysis was used to evaluate expression levels of ZFAS1 in colonic cancer tissues, cell lines, and plasma. ZEB1 and EMT‐related markers expression levels also were explored. Cell biology assays were used to explore the biologic consequences of ZFAS1 in regulating cell proliferation and invasion, as well as the roles in regulating EMT.

Results

Zinc finger antisense 1 was up‐regulated in colonic cancer tissues compared with adjacent mucosa (P < 0.01), and its expression level was significantly correlated with TNM stage, vascular invasion, and lymph node metastasis (P < 0.05). ZFAS1 and ZEB1 were also increased in patients' plasma. Moreover, ZFAS1 promoted proliferation, invasion, and impeded apoptosis. Knockdown of ZFAS1 decreased expression of ZEB1 and increased the epithelial markers E‐cadherin, ZO‐1 while decreasing mesenchymal markers vimentin and N‐cadherin.

Conclusions

Long non‐coding RNA ZFAS1 may function as an oncogene by modulating ZEB1 to induce EMT. Manipulation of ZFAS1 level may be a novel approach to suppress colonic cancer progression. In addition, ZFAS1 in plasma has the potential to be a diagnostic biomarker of colonic cancer.
Variation Across U.S. Assisted Living Facilities: Admissions, Resident Care Needs, and Staffing
Authors: Han Kihye , Trinkoff Alison M. , Storr Carla L. , Lerner Nancy , Yang Bo Kyum
Published: November 2016

Purpose

Though more people in the United States currently reside in assisted living facilities (ALFs) than nursing homes, little is known about ALF admission policies, resident care needs, and staffing characteristics. We therefore conducted this study using a nationwide sample of ALFs to examine these factors, along with comparison of ALFs by size.

Design

Cross‐sectional secondary data analysis using data from the 2010 National Survey of Residential Care Facilities.

Methods

Measures included nine admission policy items, seven items on the proportion of residents with selected conditions or care needs, and six items on staffing characteristics (e.g., access to licensed nurse, aide training). Facilities (n = 2,301) were divided into three categories by size: small, 4 to 10 beds; medium, 11 to 25 beds; and large, 26 or more beds. Analyses took complex sampling design effects into account to project national U.S. estimates.

Findings

More than half of ALFs admitted residents with considerable healthcare needs and served populations that required nursing care, such as for transfers, medications, and eating or dressing. Staffing was largely composed of patient care aides, and fewer than half of ALFs had licensed care provider (registered nurse, licensed practical nurse) hours. Smaller facilities tended to have more inclusive admission policies and residents with more complex care needs (more mobility, eating and medication assistance required, short‐term memory issues, p < .01) and less access to licensed nurses than larger ALFs (p < .01).

Conclusions

This study suggests ALFs are caring for and admitting residents with considerable care needs, indicating potential overlap with nursing home populations. Despite this finding, ALF regulations lag far behind those in effect for nursing homes. In addition, measurement of care outcomes is critically needed to ensure appropriate ALF care quality.

Clinical Relevance

As more people choose ALFs, outcome measures for ALFs, which are now unavailable, should be developed to allow for oversight and monitoring of care quality.
Stem cell bioprinting for applications in regenerative medicine
Authors: Tricomi Brad J. , Dias Andrew D. , Corr David T.
Published: November 2016

Many regenerative medicine applications seek to harness the biologic power of stem cells in architecturally complex scaffolds or microenvironments. Traditional tissue engineering methods cannot create such intricate structures, nor can they precisely control cellular position or spatial distribution. These limitations have spurred advances in the field of bioprinting, aimed to satisfy these structural and compositional demands. Bioprinting can be defined as the programmed deposition of cells or other biologics, often with accompanying biomaterials. In this concise review, we focus on recent advances in stem cell bioprinting, including performance, utility, and applications in regenerative medicine. More specifically, this review explores the capability of bioprinting to direct stem cell fate, engineer tissue(s), and create functional vascular networks. Furthermore, the unique challenges and concerns related to bioprinting living stem cells, such as viability and maintaining multi‐ or pluripotency, are discussed. The regenerative capacity of stem cells, when combined with the structural/compositional control afforded by bioprinting, provides a unique and powerful tool to address the complex demands of tissue engineering and regenerative medicine applications.
Cartilage extracellular matrix as a biomaterial for cartilage regeneration
Authors: Kiyotake Emi A. , Beck Emily C. , Detamore Michael S.
Published: November 2016

The extracellular matrix (ECM) of various tissues possesses the model characteristics that biomaterials for tissue engineering strive to mimic; however, owing to the intricate hierarchical nature of the ECM, it has yet to be fully characterized and synthetically fabricated. Cartilage repair remains a challenge because the intrinsic properties that enable its durability and long‐lasting function also impede regeneration. In the last decade, cartilage ECM has emerged as a promising biomaterial for regenerating cartilage, partly because of its potentially chondroinductive nature. As this research area of cartilage matrix–based biomaterials emerged, investigators facing similar challenges consequently developed convergent solutions in constructing robust and bioactive scaffolds. This review discusses the challenges, emerging trends, and future directions of cartilage ECM scaffolds, including a comparison between two different forms of cartilage matrix: decellularized cartilage (DCC) and devitalized cartilage (DVC). To overcome the low permeability of cartilage matrix, physical fragmentation greatly enhances decellularization, although the process itself may reduce the chondroinductivity of fabricated scaffolds. The less complex processing of a scaffold composed of DVC, which has not been decellularized, appears to have translational advantages and potential chondroinductive and mechanical advantages over DCC, without detrimental immunogenicity, to ultimately enhance cartilage repair in a clinically relevant way.
Pulmonary Vein Isolation with the Cryoballoon Technique: Feasibility, Procedural Outcomes, and Adoption in the Real World
Authors: PADELETTI LUIGI , CURNIS ANTONIO , TONDO CLAUDIO , LUNATI MAURIZIO , PORCELLINI STEFANO , VERLATO ROBERTO , SCIARRA LUIGI , SENATORE GAETANO , CATANZARITI DOMENICO , LEONI LOIRA , LANDOLINA MAURIZIO , DELISE PIETRO , IACOPINO SAVERIO , PIERAGNOLI PAOLO , ARENA GIUSEPPE
Published: November 2016

Background

Catheter ablation (CA) is recommended for patients with drug refractory symptomatic atrial fibrillation (AF). “One Shot” catheters have been introduced to simplify CA and cryoballoon ablation (CBA) is spreading rapidly. Few real‐world data are available on standard clinical practice, mainly from single‐center experience. We aimed to evaluate clinical settings, demographics, and acute procedural outcomes in a large cohort of patients treated with CBA.

Methods

A total of 903 patients (73% male, mean age 59 ± 11) underwent pulmonary vein CBA. Correlations between the patient's inclusion time and clinical characteristics, procedure duration, acute success rate, and intraprocedural complications were evaluated.

Results

Seventy‐seven percent of patients were affected by paroxysmal AF and 23% by persistent AF. Overall, acute success rate was 97.9% and periprocedural complications were observed in 35 (3.9%) patients, 13 (1.4%) of which were classified as major complications. With respect to the patient's inclusion time analysis, an increase in treatment of persistent AF was observed, a significant decrease in CBA times (procedure, ablation, and fluoroscopy: 136.0 ± 46.5 minutes, 28.8 ± 19.6 minutes, and 34.3 ± 15.4 minutes, respectively) was observed, with comparable acute success rate and intraprocedural complications over time. The rate of major complications was extremely low (1.4%); no death, atrioesophageal fistula, stroke, or other major periinterventional or late complications occurred.

Conclusion

This series represents the largest experience of CBA in the treatment of AF that also describes the adoption curve of this relatively recent technology. CBA showed an excellent safety profile when performed in a large real‐world clinical setting, with satisfactory acute success rate and, on average, short procedural times.

Clinical Trial Registration

clinicaltrials.gov (NCT01007474)
The plumage and colouration of an enantiornithine bird from the early cretaceous of china
Authors: Peteya Jennifer A. , Clarke Julia A. , Li Quanguo , Gao Ke‐Qin , Shawkey Matthew D.
Published: November 2016

Brilliant colour displays and diverse feather morphologies that are often sexual ornaments are common throughout much of extant Avialae. Here we describe a new basal enantiornithine bird specimen recovered from the Early Cretaceous Jiufotang Formation of Liaoning Province in northeastern China. We present new information on the plumage of Bohaiornithidae as well as the first detailed colour reconstruction of an enantiornithine bird. The new specimen retains subadult skeletal characteristics, including periosteal pitting of the long bone epiphyses and unfused elements, while also preserving plumage evidence consistent with sexual maturity at the time of death. Exceptionally‐preserved feathers cover the body, including elongate crown feathers, body contour feathers, asymmetrically‐veined wing primaries, an alula and two elongate rachis‐dominated rectrices that may have been sexual ornaments. The crown, neck, and body contour feathers retain elongate melanosome morphologies associated with weakly iridescent colouration in extant feathers. We provide additional evidence of preserved melanin using Raman spectroscopy; a rapid, non‐destructive chemical technique. The new specimen provides data on skeletal ontogeny in the Bohaiornithidae as well as evidence for intraspecific communication functions of plumage.
A cry for help or sexual perfumes? An alternative hypothesis for wasp attraction to the scent of caterpillar‐wounded plants
Authors: Kaplan Ian
Published: November 2016

This article comments on: Combined use of herbivore‐induced plant volatiles and sex pheromones for mate location in braconid parasitoids
Local Peacebuilding, Trauma, and Empowerment in Bosnia–Herzegovina
Authors: Parent Geneviève
Published: November 2016

The main argument of this article emphasizes the intimate connections which exist between the opportunity for participation and the possibilities of healing in the peacebuilding context of Bosnia–Herzegovina (BiH). More specifically, the goal is to examine how trauma is managed in such a way as to exclude the nonelite locals—the ordinary citizens—labeled as traumatized and how this exclusion affects both the “traumatized” and the potential outcomes of peacebuilding initiatives in BiH. In this article, it is argued that marginalized ordinary citizens are caught in a vicious circle that impedes the healing of their trauma and results in their exclusion from peacebuilding processes. This situation allows disempowerment to fester and grow, hinders the healing process, and undermines peacebuilding efforts. Based on data gathered through multiple field trips, this article also shows that the ordinary citizens are intuitively aware of the connections between participation, trauma, and political access, thus suggesting the power relations and political stakes inherent in local participation and trauma‐related activities.
Cryptochromes Orchestrate Transcription Regulation of Diverse Blue Light Responses in Plants
Authors: Yang Zhaohe , Liu Bobin , Su Jun , Liao Jiakai , Lin Chentao , Oka Yoshito
Published: November 2016

Blue light affects many aspects of plant growth and development throughout the plant lifecycle. Plant cryptochromes (CRYs) are UV‐A/blue light photoreceptors that play pivotal roles in regulating blue light‐mediated physiological responses via the regulated expression of more than one thousand genes. Photoactivated CRYs regulate transcription via two distinct mechanisms: indirect promotion of the activity of transcription factors by inactivation of the COP1/SPA E3 ligase complex or direct activation or inactivation of at least two sets of basic helix–loop–helix transcription factor families by physical interaction. Hence, CRYs govern intricate mechanisms that modulate activities of transcription factors to regulate multiple aspects of blue light‐responsive photomorphogenesis. Here, we review recent progress in dissecting the pathways of CRY signaling and discuss accumulating evidence that shows how CRYs regulate broad physiological responses to blue light.
Infertility associated with the absence of endometrial progesterone receptors in a bitch
Authors: Dockweiler JC , Cossic B , Donnelly CG , Gilbert RO , Buckles E , Cheong SH
Published: November 2016

Contents

A three‐year‐old intact female Old English sheepdog was presented for evaluation of infertility. A uterine biopsy was performed during dioestrus, and the microscopic appearance was inconsistent with progesterone stimulation; the glands were sparse, simple and failed to show coiling, while the glandular epithelium was cuboidal instead of columnar. There was very little evidence of glandular activity. Due to the inappropriate appearance of the glands for the stage of the cycle, immunohistochemistry for progesterone receptors was performed. No progesterone receptor‐positive immunoreactivity was identified in the endometrial luminal epithelium, glandular epithelium or stroma. Weak intranuclear immunoreactivity was identified within the smooth muscle cells of the myometrium. The absence of progesterone receptors within the endometrial glands is the most likely explanation for the abnormal appearance of the endometrium and for this bitch's infertility. To our knowledge, this is the first report of endometrial progesterone receptor absence in a bitch.
Teaching Resistance to Narrative: Brecht's Theater Praxis as a Response to Florian Henckel von Donnersmarck'sDas Leben der Anderen
Authors: Koerner Morgan
Published: November 2016

This article explores the potential of Brecht's theater praxis for teaching millennial students to question dramatic narratives and rethink their own spectatorial positions, especially in regards to mainstream cinema that emphasizes character identification and plot. The article reflects on a five‐day teaching unit on Brecht's theater in a senior level German course that began and ended with Florian Henckel von Donnersmarck'sDas Leben der Anderen, a film that appropriates Brecht within an aesthetics Einfühlung. The first section makes the unusual case for organizing a unit on Brecht's theater praxis aroundDas Leben der Anderendescribes how the aesthetic program presented in the film offers an ideal foil for Brecht's theater. The second segment describes how the class applied Brecht's theories and theater strategies to the film by reducing the plot to a six‐scene fable, constructing tableaux that summarized each scene, and insertingV‐Effektewith critical commentaries on the film. In closing, I discuss the results of students’ writing assignments and in‐class theater work as well as their feedback on the unit, and I make an argument for teaching theater as a hypermedium that can encourage students to explore different modes of thinking and interrogate the ways in which their own media consumption has trained them to perceive.
How to encourage non‐donors to be more willing to donate blood? Testing of binding communication based interventions
Authors: Fonte D. , Blondé J. , Girandola F.
Published: November 2016

SUMMARY

Objectives

Our study aims to test the effectiveness of binding communication based interventions (vs classical persuasive communication based ones) inciting non‐donors to act in favour of blood donation.

Background

The implementation of effective communication interventions represents a major public health issue. Nevertheless, persuasive media campaigns appear to have little effect on behaviours. Even though non‐donors hold a positive attitude towards blood donation, they are not inclined to donate. As an alternative to producing behavioural changes, many recent studies have shown the superiority of binding communication over persuasive communication.

Methods

All participants, non‐donors, were randomly assigned to one of four experimental conditions of a 2 (type of communication: persuasive vs binding) × 2 (source credibility: low vs high) factorial design. Then, they were asked to report their intention to donate blood, and their intention to distribute leaflets regarding blood donation.

Results

Binding communication is a more effective strategy for increasing intention towards blood donation compared with persuasive communication, especially when combined with high credibility source.

Discussion

Accordingly this study calls for more consideration of knowledge of social psychology to design effective communication interventions and increase the number of donations.
A role for red cell clearance in antibody‐mediated inhibition of erythrocyte alloimmunization?
Authors: Marjoram D. , Cruz‐Leal Y. , Bernardo L. , Lazarus A. H.
Published: November 2016

Antibodies targeting erythrocytes can induce antibody‐mediated inhibition of erythrocyte alloimmunization, and anti‐D has been extremely successful in preventing haemolytic disease of the foetus and newborn (HDFN). It is desirable to replace the current donor‐derived anti‐D with a monoclonal antibody; however, the exact mechanism of IgG‐mediated suppression of red blood cell immune responses remains unclear. It has been proposed that the ability of anti‐D to prevent HDFN is due to IgG interactions with Fc receptors on phagocytic cells leading to rapid clearance of RhD+ red cells. Several monoclonal anti‐D alternatives have been developed with an emphasis on their ability to rapidly clear red blood cells from the circulation. None of the monoclonal antibodies have been as effective as donor‐derived anti‐D with some antibodies inadvertently leading to immune enhancement instead of inhibition. A better understanding of the mechanisms of IgG‐mediated inhibition of red cell alloimmunization is necessary. In this brief review, we highlight selected evidence for and against the requirement for rapid red cell clearance in the ability of IgG to prevent red cell alloimmunization. We also discuss potential alternative mechanisms which could be important for informing the future development of monoclonal antibody alternatives.
Effect of the Wettability on the IR Laser Photothermally Induced Phase Change in Microchannels
Authors: He Xuefeng , Chen Rong , Zhu Xun , Liao Qiang
Published: November 2016

In this paper, the IR laser photothermally induced phase change characteristics in the microchannels with different wettabilities were studied using visual experiments. The hydrophobic microchannel was obtained by the hydrophobic nature of the PDMS material while the hydrophilic microchannels were obtained by the inert gas plasma surface treatments. Effects of the contact angle, laser power and spot position were investigated. It is interesting to find the change of the wettability and laser power could alter the phase change behaviors. The hydrophobic microchannel showed the interface advancement at low laser power and the liquid slug formation accompanying with the interface receding at high laser power. For less hydrophilic microchannel, the liquid slug formation accompanying with the interface receding was observed at low laser power while the sole interface receding was observed at high laser power. For more hydrophilic microchannel, the sole interface receding was observed for both low and high laser powers. Besides, it was also found that increasing the distance between the initial interface location and laser spot led to the increased thermal resistance, lowering the evaporation rate and thereby the above-mentioned effect.
Simulation of a Yield Stress Influence on Nusselt Number in Turbulent Flow of Kaolin Slurry
Authors: Bartosik Artur
Published: November 2016

Solid-liquid flow commonly exists in nature and in engineering and its modeling is one of the main challenges of Computational Fluid Dynamics.

The paper deals with numerical simulation of mass and heat transfer in turbulent flow of Kaolin slurry. The physical model assumes that solid particles are sufficiently small and fully suspended, and a turbulent flow is hydro-dynamically and thermally developed in a straight horizontal pipeline. Based upon the assumptions the slurry is considered to be a single-phase flow with increased density and apparent viscosity. As the slurry exhibits a yield stress, the Bingham rheological model was chosen to calculate its apparent viscosity. The mathematical model uses the time-averaged momentum equation in which the turbulent stress tensor was defined by means of the k-ε model, which makes use of the Boussinesq eddy-viscosity hypothesis. The turbulence damping function, which has been used in the k-ε model, was purposely designed for such slurry because the slurry exhibits increased damping of turbulence. In addition, the energy equation has been used. The convective term of the equation was determined from the energy balance acting on a unit pipe length, assuming linear changes of temperature in the main flow direction.

The objective of the paper is to examine the influence of yield stress on the Nusselt number in the turbulent flow of Kaolin slurry in the range of solids concentration between 0% and 38% by volume and in the range of Reynolds numbers from 5,000 to 50,000. The paper shows that there is a substantial influence of the yield stress on velocity profiles and consequently on the temperature profiles and Nusselt number. The results of numerical simulation demonstrate the importance of turbulence damping near a pipe wall. A possible cause of turbulence damping in the near-wall region is also discussed.
Numerical Study on Natural Convection From a Row of Heated Pipes Embedded in an Air-Filled Cavity
Authors: Ngo C. C. , Alhabeeb B. A.
Published: November 2016

Heat transfer from a buried pipe has been a subject of great interest due to its many important engineering applications, which include the underground pipelines for oil and gas transport and the power cables. The problem considered in the present study has applications related to a radiant underfloor heating system in residence and industry. In the existing literature, heat transfer from a buried pipe has been considered for various heat transfer modes and configurations. For example, analytical solutions are readily available for heat conduction from one single cylindrical heat source or multiple heat sources, and the heat transfer results are often expressed in terms of the conduction shape factor. As for heat convection from an array of pipes, most of the existing studies have been focused on external crossflow with forced convection from a bundle of pipes with either aligned or staggered pipe arrangement. This area of research has received much attention due to its important industrial applications in the design of boilers and heat exchangers. On the other hand, studies involved natural convection from an array of pipes are relatively limited.

The problem considered in the present study is related to the simulation of underfloor piping systems suspended in the joist space beneath the subfloor. Natural convective heat transfer from a row of horizontal heated pipes embedded in a closed cavity filled with air has been numerically examined in this study. A two-dimensional steady-state model has been developed using ANSYS Fluent for the numerical simulation. A parametric study has been performed to investigate the effects of pipe spacing, pipe depth and pipe temperature on the flow patterns and heat transfer rates. The heat transfer mechanism from the heated pipes to the top surface of the air-filled cavity is revealed through the plots of streamlines and isotherms. The present numerical model has been developed and validated using a parallel experimental study. From the radiant underfloor heating application perspective, the results showed that a radiant heating system with pipes embedded at a shallow burial depth and placed closer together resulted with a more desired surface temperature distribution.
Thermophysical Properties of Two-Phase Refrigerant Based Nanofluids in a Refrigeration Cycle
Authors: Tekin Bilgehan , G. Yazicioglu Almila
Published: November 2016

Nanofluids are a class of fluids with nanoparticles suspended in a base fluid. The aim for using nanofluids is often to improve the thermophysical properties of the base fluid so as to enhance the energy transfer efficiency. As the technology develops; the size of devices and systems needs to get smaller to fulfill the engineering requirements and/or to be leading among competitors. The use of nanofluids in heat transfer applications seems to be a viable solution to current heat transfer problems, albeit with certain limitations. As an enhancing factor for the thermal conductivity of the base fluid, nanofluids are considered to be use in cooling system applications. For these applications, the base fluid, the refrigerant, exists as a two-phase liquid-vapor mixture in parts of the refrigeration cycle. To analyze, design and optimize the cycle in such applications, the thermophysical properties of the refrigerant based nanofluids for two-phase flow of refrigerant are needed. There are different models present in the literature derived for the thermophysical properties of nanofluids. However, a majority of the existing models for nanofluid thermophysical properties have been proposed for water- and other liquids-based nanofluids, through theoretical, numerical and experimental research. Therefore, the existing models for determination of the nanofluid thermophysical properties are not applicable for refrigerant based nanofluid applications when the results are compared. Thus, in this work, a new model is derived for the thermal conductivity and viscosity of refrigerant based nanofluids, using existing data from both heat transfer and thermophysical property measurement experiments. The effect of the nanoparticles on heat transfer in two phase flow of the refrigerant is considered by applying the two phase heat transfer correlations in the literature to experimental data. As a result, the thermophysical properties of the known states are determined through known heat transfer performance. Even though the model is developed from the analysis of flow in an evaporator and flow in a single tube with evaporating refrigerant, it is aimed to cover the flows in both evaporator and condenser sections in a vapor compression refrigeration cycle to provide the necessary models for thermophysical properties in heat transfer devices which will allow the design of both cycle and evaporator or condenser in terms of sizing and rating problems by performing heat transfer analysis and/or optimization. The model can also be improved by considering the effects of slip mechanisms that lead to slip velocity between the nanoparticle and base fluid.
Local Heat Transfer Coefficients Measurement Under Micro Jet Impinging Using Nitrogen Gas (N2)
Authors: Shin Jeong-Heon , Rozenfeld Tomer , Vutha Ashwin , Wang Yingying , Ziskind Gennady , Peles Yoav
Published: November 2016

Experimental and simulation studies were performed to reveal local heat transfer coefficients under jet impinging in micro domain with Nitrogen gas. The experimental device was made of a 500 μm thick Pyrex and 400 μm thick silicon wafers. On the Pyrex wafer, four 100 nm thick resistance temperature detector (RTD) thermistors and a heater were fabricated from titanium. Jet orifices were etched by deep reactive ion etching (DRIE) on a silicon wafer, which was attached to the Pyrex wafer through a vinyl sticker (250 μm thick). A 1.9 mm × 14.8 mm × 250 μm micro channel was formed by laser drilling into the sticker.

Varying flow rates of Nitrogen gas and heat fluxes of the heater, temperatures of the four thermistors were collected and local heat transfer coefficients were inferred enabling to divulge the jet impinging cooling characteristics. Initial simulations were used to complement experiments and to obtain detailed flow patterns of the jet, temperature distribution on the heater area, and fluid temperature distribution.
Effect of Heat Source Geometry on the Transient Heat Transfer During Melting Process of a PCM
Authors: Bashar Mohammad , Siddiqui Kamran
Published: November 2016

Thermal energy storage (TES) systems using phase change materials (PCMs) are used in various engineering applications. TES is a means by which heat is ‘hold’ for a certain period of time for use at a later time. We report an experimental study which was conducted to investigate the melting process and associated heat transfer in a rectangular chamber with a cylindrical u-shaped heat source imbedded inside the PCM. The results showed that geometry and orientation of the heat source immensely influenced the heat transfer behavior during solid-liquid phase transition. The heat transfer behavior, interface movement and the heat transfer coefficients differed both axially and vertically inside the chamber as well as with the melting rate. The local convective heat transfer coefficient, hlocal in the inner region, enclosed by the U-tube, was observed to increase at a higher rate than the outer region. Stronger convective flow and a lower viscosity owing to higher temperature in the inner region is believed to have caused faster melting in this region. The melting rate was also found comparatively higher until approximately two-third of the PCM volume was melted before the rate declined.
Nusselt Numbers for Fully-Developed Flow Between Parallel Plates With One Plate Textured With Isothermal Parallel Ridges
Authors: Karamanis Georgios , Hodes Marc , Kirk Toby , Papageorgiou Demetrios T.
Published: November 2016

We develop a semi-analytical solution for the Nusselt number for fully-developed flow of liquid between parallel plates, one of which is textured with isothermal parallel ridges. The opposite plate is smooth and adiabatic. The liquid is assumed to be in the Cassie state on the textured surface, on which a mixed boundary condition of no slip on the ridges and no shear along menisci applies. An existing solution for the velocity field is valid. The thermal energy equation is subjected to a mixed isothermal-ridge and adiabatic-meniscus boundary condition on the textured surface. Given the nature of the isothermal boundary condition, the analysis concerns a three-dimensional developing temperature profile, and the results are obtained for a streamwise location that tends to infinity. We assume that the temperature field is governed by an infinite sum of the product of a function of the streamwise coordinate and a second function of the spanwise co-ordinates. The latter functions are eigenfunctions satisfying a two-dimensional Sturm-Liouville problem from which the eigenvalues follow. The fully-developed Nusselt number follows from the first eigenvalue.
Numerical Investigation of Heat Transfer and Condensation Rate in Two-Stage Transport Membrane Condenser Heat Exchanger Units
Authors: Soleimanikutanaei Soheil , Lin Cheng-Xian , Wang Dexin
Published: November 2016

Heat and water recovery using Transport Membrane Condenser (TMC) based heat exchangers is a promising technology in power generation industry. In this type of innovative heat exchangers the tube walls are made of a nano-porous material and have a high membrane selectivity which is able to extract condensate water from the flue gas in the presence of the other non-condensable gases such as CO2, O2 and N2. Considering the fact that for industrial applications, a matrix of TMC heat exchangers with several TMC modulus in the cross section or along the flow direction is necessary. Numerical simulation of multi-stage TMC heat exchanger units is of a great importance in terms of design, performance evaluation and optimization. In this work, performance of a two-stage TMC heat exchanger unit has been studied numerically using a multi-species transport model. In order to investigate the performance of the two-stage TMC heat exchanger unit, parametric study on the effect of transversal and longitudinal pitches in terms of heat transfer, pressure drop and condensation rate inside the heat exchangers have been carried out. The results indicate that the heat transfer and condensation rates both increase by reducing TMC tube pitches in the second stage and increasing the number of TMC tube pitches in the first stage of the units.
A Novel Machine-Learning Aided Optimization Technique for Material Design: Application in Thin Film Solar Cells
Authors: Hajimirza Shima
Published: November 2016

Patterned thin film structures can offer spectrally selective radiative properties that benefit many engineering applications including photovoltaic energy conversion at extremely efficient scales. Inverse design of such structures can be expressed as an interesting optimization problem with a specific regime of complexity; namely moderate number of optimization parameters but highly time-consuming forward problem. For problems like this, a search technique that can somehow learn and parameterize the multi-dimensional behavior of the objective function based on past search points can be extremely useful in guiding the global search algorithm and expediting the solution for such complexity regimes. Based on this idea, we have developed a novel search algorithm for optimizing absorption coefficient of visible light in a multi-layered silicon-based nano-scale thin film solar cell. The proposed optimization algorithm uses a machine-learning predictive tool called regression-tree in an intermediary step to learn (i.e. regress) the objective function based on a previous generation of random search points. The fitted model is then used as a guide to resample from a new generation of candidate solutions with a significantly higher average gain. This process can be repeated multiple times and better solutions are obtained with high likelihood at each stage. Through numerical experiments we demonstrate how in only one resampling stage, the propose technique dominates the state-of-the-art global search algorithms such as gradient based techniques or MCMC methods in the considered nano-design problem.
Characterization Phase Change Materials (PCM) Using T-History Method
Authors: Kumar Navin , Banerjee Debjyoti
Published: November 2016

“T-history method” is widely used for characterization of thermal properties of Phase Change Material (PCM). In this study improvements are proposed to the experimental protocol used in the conventional T-History method. Experimental validation of numerical predictions for various samples of PCM were performed using the proposed measurement technique. This enabled the evaluation of the improvements in the proposed approach as well as for analyzing the experimental results. This involved measurement of temperature at the surface and in the center of the PCM samples (as well as that of the reference sample materials). The proposed modifications enable enhanced accuracy for estimation of the material properties (when compared to the conventional approaches). The estimates from the proposed approach were observed to be within 10% of the measured values obtained using Differential Scanning Calorimetry (DSC). The proposed approach is amenable to testing large sample sizes, is simpler to implement, provides more rapid data collection and is more cost-effective than that obtained using standard DSC protocols.
An Experimental Study of Boiling Heat Transfer During Quenching of Nanofluids With Carbon Nanotubes of Various Sizes
Authors: Li Jia-Qi , Fan Li-Wu , Zhang Liang , Yu Zi-Tao
Published: November 2016

Quenching experiments were performed with hot stainless steel spheres in a pool of water-based nanofluids in the presence of carbon nanotubes (CNTs) of various sizes. In order to explore the size effect, a test matrix was developed by choosing multi-walled CNTs with lengths from 1 μm to 5 μm and outer diameters from 30 nm to 60 nm. The concentration was fixed at 0.5% by mass for all types of CNTs. The initial temperature was 400 °C and the transient temperature variations at the center of the sphere were recorded as quenching curves. By establishing a lumped capacitance model, the transient surface heat flux variations were obtained as boiling curves. The original and boiled surfaces were both subjected to a series of characterizations to determine the changes in morphology, roughness, and wettability to identify the effects of CNT size on the surface properties of the formed deposition layers as well as to elucidate the mechanisms for regulation of the boiling and quenching behaviors. The results suggested that the critical heat flux (CHF) and the Leidenfrost point (LFP) are enhanced to various degrees due to the discrepancy in the size of the CNTs in nanofluids. It was shown that the CNTs deposited on the surfaces create various morphologies depending on their size. The CNTs with a length of 5 μm and a diameter of 60 nm exhibited the most significant effect on the boiling behaviors. In comparison to CNTs with a shorter length of 1 μm, the 5 μm long CNTs were much easier to form porous layers. The results of the contact angle and roughness tests showed that the porous layers tend to affect the surface roughness instead of surface wettability. The increases of the nucleation site density and surface roughness due to the presence of porous layers were identified as the primary cause for the modified boiling behaviors during quenching.
Turbulent Natural Convection in a Composite Enclosure Using the Thermal Non-Equilibrium Model
Authors: de Lemos Marcelo J. S. , Masciarelli Caio B.
Published: November 2016

Turbulent natural convection in a two-dimensional horizontal composite square cavity is numerically analyzed using the finite volume method and the thermal non-equilibrium approach. Distinct energy equations for the working fluid and for the porous matrix are proposed reflecting different energy balances for each phase. The composite square cavity is formed by three distinct regions, namely, clear, porous and solid region. It was found that the fluid begins to permeate the porous medium for values of Ra greater than 10^6. Nusselt number values show that for the range of Ra analyzed there are no significant variation between the laminar and turbulent model solution. When comparing the effects of Ra and Da on Nu, results indicate that the solid phase properties have a greater influence in enhancing the overall heat transferred trough the cavity.