bluuebunny/crossref_metadata_2025 huggingface dataset:
Metal‐specific control of gene expression mediated by Bradyrhizobium japonicumMur and Escherichia coliFur is determined by the cellular context
Authors: Hohle Thomas H. , O'Brian Mark R.
Published: March 2016

Bradyrhizobium japonicum Mur and Escherichia coli Fur are manganese‐ and iron‐responsive transcriptional regulators, respectively, that belong to the same protein family. Here, we show that neither Mur nor Fur discriminate between Fe2+ and Mn2+in vitro nor is there a metal preference for conferral of DNA‐binding activity on the purified proteins. When expressed in E. coli, B. japonicum Mur responded to iron, but not manganese, as determined by in vivo promoter occupancy and transcriptional repression activity. Moreover, E. coli Fur activity was manganese‐dependent in B. japonicum. Total and chelatable iron levels were higher in E. coli than in B. japonicum under identical growth conditions, and Mur responded to iron in a B. japonicum iron export mutant that accumulated high levels of the metal. However, elevated manganese content in E. coli did not confer activity on Fur or Mur, suggesting a regulatory pool of manganese in B. japonicum that is absent in E. coli. We conclude that the metal selectivity of Mur and Fur depends on the cellular context in which they function, not on intrinsic properties of the proteins. Also, the novel iron sensing mechanism found in the rhizobia may be an evolutionary adaptation to the cellular manganese status.
Two ways to skin a cat: acyldepsipeptides antibiotics can kill bacteria through activation or inhibition of ClpP activity
Authors: Vass Robert H. , Chien Peter
Published: March 2016

Infection by Mycobacterium tuberculosis (Mtb) has had a devastating effect on the world population. Acyldepsipeptide antibiotics (ADEPs) are known to kill some bacteria by over activating the bacterial ClpP peptidase. ADEP antibiotics also target Mtb, with the assumption that uncontrolled ADEP‐activated proteolysis by ClpP is the common mode of killing. In this issue of Molecular Microbiology, Famulla, et al. now show that ADEP's effectiveness in mycobacteria is likely due to inhibition of ClpP‐dependent protease activity rather than activation. This finding of how the same antibiotic can kill bacteria by either inhibiting or activating proteases illustrates the utility of targeting these enzymes for sorely needed new antibiotics.
Multiple myeloma in the marrow: pathogenesis and treatments
Authors: Fairfield Heather , Falank Carolyne , Avery Lindsey , Reagan Michaela R.
Published: March 2016

Multiple myeloma (MM) is a B cell malignancy resulting in osteolytic lesions and fractures. In the disease state, bone healing is limited owing to increased osteoclastic and decreased osteoblastic activity, as well as an MM‐induced forward‐feedback cycle where bone‐embedded growth factors further enhance tumor progression as bone is resorbed. Recent work on somatic mutation in MM tumors has provided insight into cytogenetic changes associated with this disease; the initiating driver mutations causing MM are diverse because of the complexity and multitude of mutations inherent in MM tumor cells. This manuscript provides an overview of MM pathogenesis by summarizing cytogenic changes related to oncogenes and tumor suppressors associated with MM, reviewing risk factors, and describing the disease progression from monoclonal gammopathy of undetermined significance to overt MM. It also highlights the importance of the bone marrow microenvironment (BMM) in the establishment and progression of MM, as well as associated MM‐induced bone disease, and the relationship of the bone marrow to current and future therapeutics. This review highlights why understanding the basic biology of the healthy and diseased BMM is crucial in the quest for better treatments and work toward a cure for genetically diverse diseases such as MM.
Mapping urban Māori: A population‐based study of Māori heterogeneity
Authors: Ryks John , Pearson Amber L. , Waa Andrew
Published: March 2016

Urban Māori is a term that describes indigenous people in Aotearoa New Zealand living in urban environments. It includes Māori who hold traditional authority over land (mana whenua) and Māori who have moved away from their traditional homes (mātāwaka). This article describes the heterogeneity of the urban Māori population through the spatial analysis of iwi (tribal) census data for four urban centres. The results show complex variation in the distribution of mana whenua and mātāwaka populations and help to inform a discussion about the rights and interests of all urban Māori in the development and planning of cities, and subsequent policy responses.
Spitz Nevus: A Rare Lesion of the Oral Cavity
Authors: Vaccaro Mario , Romeo Umberto , Romeo Carmelo , Lentini Maria
Published: March 2016

Pigmented mucosal lesions represent a group of rare entities with different etiopathogenetic origins, histopathologic features, dermoscopic appearances, and clinical course. Solitary pigmented lesions of melanocytic origin are uncommon in the oral mucosa, and intraoral occurrence of Spitz nevus is very rare. Here we present a case of Spitz nevus occurring on the hard palate of a 26‐month‐old boy.
Effects of a New Emollient‐Based Treatment on Skin Microflora Balance and Barrier Function in Children with Mild Atopic Dermatitis
Authors: Bianchi Pascale , Theunis Jennifer , Casas Christiane , Villeneuve Cecile , Patrizi Annalisa , Phulpin Chloe , Bacquey Adeline , Redoulès Daniel , Mengeaud Valerie , Schmitt Anne‐Marie
Published: March 2016

Background/Objectives

The use of emollients is widely recommended for the management of atopic dermatitis (AD), especially between flares. An imbalance of skin microflora is suspected of playing a key role in exacerbations of AD. Our aim was to evaluate the effect of a new emollient balm on clinical parameters (SCORing Atopic Dermatitis [SCORAD], xerosis, pruritus), skin barrier function (transepidermal water loss and loricrin, filaggrin, corneodesmosin, and involucrin expression], skin microflora biodiversity, and Staphylococcus aureus and Staphylococcus epidermidis balance in children with mild AD.

Methods

Fifty‐four children (1–4 yrs old) were enrolled in this randomized, controlled study. Subjects applied a hygiene product and the emollient balm (emollient group, n = 28) or the hygiene product only (control group, n = 26) twice a day for 28 days.

Results

We found improvement in favor of the emollient group in SCORAD (p < 0.001), pruritus (p = 0.06), and xerosis (p = 0.06) after 28 days of application. Moreover, transepidermal water loss decreased in the emollient group by 34% (p = 0.06) and involucrin expression by 37% (p = 0.001) at day 28 from baseline in association with improvement in barrier function, whereas other barrier‐specific proteins did not vary. S. aureus increased significantly in the control group only (6.5 times, p = 0.01), whereas S. epidermidis remained stable in both groups. The Shannon index (H′ = 2.3) did not vary with treatment in either group.

Conclusion

Twice‐daily application of a new emollient balm in children with mild AD protected the skin from S. aureus proliferation and preserved microflora biodiversity.
Port‐Wine Stain–Like Presentation of a Tufted Angioma on the Face
Authors: Tobe Joshua , Shum David , Somers Gino R. , Pope Elena , Mohammed Javed Ayoub
Published: March 2016

Tufted angioma is an uncommon benign vascular tumor that typically is noted during infancy or childhood, with variable clinical presentation. We report the case of an infant with a tufted angioma initially presenting as a port‐wine stain–like patch of the left cheek.
Ceteris ParibusLaws andMinutis RectisLaws
Authors: Fenton‐Glynn Luke
Published: March 2016

Special science generalizations admit of exceptions. Among the class of non‐exceptionless special science generalizations, I distinguish (what I will call)minutis rectis(mr) generalizations from the more familiar category ofceteris paribus(cp) generalizations. I argue that the challenges involved in showing thatmrgeneralizations can play the law role are underappreciated, and quite different from those involved in showing thatcpgeneralizations can do so. I outline a strategy for meeting the challenges posed bymrgeneralizations.
Germination sensitivity to water stress in four shrubby species across the Mediterranean Basin
Authors: Chamorro D. , Luna B. , Ourcival J.‐M. , Kavgacı A. , Sirca C. , Mouillot F. , Arianoutsou M. , Moreno J. M.
Published: March 2016

Mediterranean shrublands are generally water‐limited and fire‐driven ecosystems. Seed‐based post‐fire regeneration may be affected by varying rainfall patterns, depending on species sensitivity to germinate under water stress. In our study, we considered the germination response to water stress in four species from several sites across the Mediterranean Basin. Seeds of species with a hard coat (Cistus monspeliensis, C. salviifolius, Cistaceae, Calicotome villosa, Fabaceae) or soft coat (Erica arborea, Ericaceae), which were exposed or not to a heat shock and smoke (fire cues), were made to germinate under water stress. Final germination percentage, germination speed and viability of seeds were recorded. Germination was modelled using hydrotime analysis and correlated to the water balance characteristics of seed provenance. Water stress was found to decrease final germination in the three hard‐seeded species, as well as reduce germination speed. Moreover, an interaction between fire cues and water stress was found, whereby fire cues increased sensitivity to water stress. Seed viability after germination under water stress also declined in two hard‐seeded species. Conversely, E. arborea showed little sensitivity to water stress, independent of fire cues. Germination responses varied among populations of all species, and hydrotime parameters were not correlated to site water balance, except in E. arborea when not exposed to fire cues. In conclusion, the species studied differed in germination sensitivity to water stress; furthermore, fire cues increased this sensitivity in the three hard‐seeded species, but not in E. arborea. Moreover, populations within species consistently differed among themselves, but these differences could only be related to the provenance locality in E. arborea in seeds not exposed to fire cues.
Learning to license technology: the role of experience and workforce's skills in Spanish manufacturing firms
Authors: Bianchi Mattia , Lejarraga José
Published: March 2016

Firms increasingly pursue technology licensing for appropriating economic returns from their R&D investments. Despite this tendency, extracting revenues from licensing remains a challenge for most firms. This article explores the role of task‐specific experience and of workforce skills as determinants of superior licensing volume. The rationale is that these factors contribute to the development of a desorptive capacity that allows companies to overcome the complexities posed by technology licensing. Using panel data of Spanish manufacturing firms, we find that prior experience in licensing positively affects licensing revenues at a decreasing rate. These learning‐by‐doing effects are strengthened when firms have a higher proportion of their workforce endowed with advanced skills, whereas they are reduced when firms have a higher proportion of low‐skilled employees. These results contribute to licensing and open innovation research by partly specifying the nature and anatomy of desorptive capacity and by highlighting the key role of intellectual human capital in licensing, whose contribution depends on the skills level. They also inform managers on the mechanisms that can enhance their firms’ licensing volume.
Why Doomsday Arguments are Better than Simulation Arguments
Authors: Richmond Alasdair M.
Published: March 2016

Inspired by anthropic reasoning behind Doomsday arguments, Nick Bostrom's Simulation Argument says: people who think advanced civilisations would run many fully‐conscious simulated minds should also think they're probably simulated minds themselves. However, Bostrom's conclusions can (and should) be resisted, especially by sympathisers with Doomsday or anthropic reasoning. This paper initially offers a posterior‐probabilistic ‘Doomsday lottery’ argument against Bostrom's conclusions. Suggestions are then offered for deriving anti‐simulation conclusions using weaker assumptions. Anti‐simulation arguments herein use more (epistemically and metaphysically) robust reference classes than Bostrom's argument, require no Principles of Indifference, abide better by the total evidence requirement, and yet use empirically plausible priors and likelihoods. However, while Doomsday arguments are probabilistically, epistemically and metaphysically stronger than the Simulation Argument, anthropic reasoning can (and should) refrain from embracing either.
Of Disasters and Dragon Kings: A Statistical Analysis of Nuclear Power Incidents and Accidents
Authors: Wheatley Spencer , Sovacool Benjamin , Sornette Didier
Published: March 2016

We perform a statistical study of risk in nuclear energy systems. This study provides and analyzes a data set that is twice the size of the previous best data set on nuclear incidents and accidents, comparing three measures of severity: the industry standard International Nuclear Event Scale, the Nuclear Accident Magnitude Scale of radiation release, and cost in U.S. dollars. The rate of nuclear accidents with cost above 20 MM 2013 USD, per reactor per year, has decreased from the 1970s until the present time. Along the way, the rate dropped significantly after Chernobyl (April 1986) and is expected to be roughly stable around a level of 0.003, suggesting an average of just over one event per year across the current global fleet. The distribution of costs appears to have changed following the Three Mile Island major accident (March 1979). The median cost became approximately 3.5 times smaller, but an extremely heavy tail emerged, being well described by a Pareto distribution with parameter α = 0.5–0.6. For instance, the cost of the two largest events, Chernobyl and Fukushima (March 2011), is equal to nearly five times the sum of the 173 other events. We also document a significant runaway disaster regime in both radiation release and cost data, which we associate with the “dragon‐king” phenomenon. Since the major accident at Fukushima (March 2011) occurred recently, we are unable to quantify an impact of the industry response to this disaster. Excluding such improvements, in terms of costs, our range of models suggests that there is presently a 50% chance that (i) a Fukushima event (or larger) occurs every 60–150 years, and (ii) that a Three Mile Island event (or larger) occurs every 10–20 years. Further—even assuming that it is no longer possible to suffer an event more costly than Chernobyl or Fukushima—the expected annual cost and its standard error bracket the cost of a new plant. This highlights the importance of improvements not only immediately following Fukushima, but also deeper improvements to effectively exclude the possibility of “dragon‐king” disasters. Finally, we find that the International Nuclear Event Scale (INES) is inconsistent in terms of both cost and radiation released. To be consistent with cost data, the Chernobyl and Fukushima disasters would need to have between an INES level of 10 and 11, rather than the maximum of 7.
Time Preference and Income Convergence in a Dynamic Heckscher–Ohlin Model
Authors: Kawagishi Taketo , Mino Kazuo
Published: March 2016

This paper shows that income convergence in an open‐economy setting hinges upon how the time discount rate of the households is determined. As opposed to the case of constant time discount rate where cross‐country income divergence may emerge, the small open economy may catch up with the rest of the world if the time discount rate increases with consumption. In contrast, if the time discount rate decreases with consumption, then the small open economy fails to catch up with the rest of the world under free trade of commodities.
College Students' Responses to Suicidal Content on Social Networking Sites: An Examination Using a Simulated Facebook Newsfeed
Authors: Corbitt‐Hall Darcy J. , Gauthier Jami M. , Davis Margaret T. , Witte Tracy K.
Published: March 2016

Although Facebook has a peer‐initiated suicide prevention protocol, little is known about users' abilities to notice, recognize, and appropriately interpret suicidal content or about their willingness to intervene. In this study, 468 college students were randomly assigned to interact with a simulated Facebook newsfeed containing content reflecting various suicide risk levels. A larger proportion of those exposed to content reflecting moderate and severe suicide risk noticed, recognized, appropriately interpreted, and endorsed taking action to intervene, as compared to those exposed to content representing no or low risk. Overall, results indicate that college students are responsive to suicidal content on Facebook.
Transfusion‐transmitted leishmaniasis: a practical review
Authors: Jimenez‐Marco Teresa , Fisa Roser , Girona‐Llobera Enrique , Cancino‐Faure Beatriz , Tomás‐Pérez Miriam , Berenguer Diana , Guillen Carmen , Pujol Alba , Iniesta Laura , Serra Teresa , Mascaró Martín , Gascó Joan , Riera Cristina
Published: March 2016

In the Balearic Islands, as in other areas in southern Europe, there are a significant proportion of asymptomatic Leishmania infantum–infected blood donors. Theoretically, these donors may represent an important challenge for blood transfusion safety. However, despite an active search of multiply transfused patients, there have been, so far, no cases of transfusion‐transmitted leishmaniasis (TTL) in our region. On the other hand, there is scarce evidence of the TTL in the literature. A review of asymptomatic Leishmania‐infected blood donors’ studies in endemic areas and TTL reports published in the English literature were performed, to ascertain the factors that determine the real risk of transfusion transmission of Leishmania.
Platelet closure time in anesthetized Greyhounds with hemorrhagic shock treated with hydroxyethyl starch 130/0.4 or 0.9% sodium chloride infusions
Authors: McBride Duana , Hosgood Giselle , Raisis Anthea , Smart Lisa
Published: March 2016

Objective

To measure platelet closure time (PCT) in dogs during controlled hemorrhagic shock and after fluid resuscitation with hydroxyethyl starch (HES) 130/0.4 or 0.9% sodium chloride.

Design

Experimental interventional study.

Setting

University veterinary teaching hospital.

Animals

Eleven healthy Greyhounds.

Interventions

Dogs were anesthetized and had 48 mL/kg of blood removed to induce hemorrhagic shock. Dogs received 20 mL/kg of HES 130/0.4 (n= 6) or 80 mL/kg of 0.9% sodium chloride (NaCl;n= 5) intravenously over 20 minutes. PCT was measured using the Platelet Function Analyzer‐100 with collagen and adenosine‐diphosphate cartridges at: T0 = 60 minutes after induction of anesthesia prior to hemorrhage, T1 = during hemorrhagic shock, and T2 = 40 minutes after completion of fluid bolus. Packed cell volume and platelet count were concurrently measured.

Measurement and Main Results

Hemorrhagic shock did not significantly change PCT, with no difference between T0 and T1. Both the HES 130/0.4 and 0.9% NaCl group had a significantly increased mean PCT at T2 of 91.4 seconds (95% CI 69.3–113.4) and 95.5 seconds (95% CI 78.2–112.8), respectively, compared to T1. The magnitude of change was significantly greater for the 0.9% NaCl group than the HES 130/0.4 group. There was no difference in the magnitude of change in PCV and platelet count between the 2 groups. The PCV and platelet count were >25% and >100,000/μL, respectively, in all dogs, except for dogs in the HES 130/0.4 group at T2 where platelet counts were <100,000/μL.

Conclusion

Controlled hemorrhagic shock in Greyhounds under anesthesia did not cause a significant change in PCT. Both HES 130/0.4 and 0.9% NaCl administration after induction of shock increased PCT. These results do not support that HES 130/0.4 causes relevant platelet dysfunction beyond hemodilution.
“We Have Seen Other Countries and Have Another Culture.” Migrant Domestic Workers and The International Production and Circulation of Feminist Knowledge and Organization
Authors: Federici Silvia
Published: March 2016

This article argues that a movement of domestic workers has developed internationally that through its struggles is promoting elements of a feminist agenda, revalorizing the work of reproduction, forcing a new generation of feminists to again confront the housework question, and in this process generating new forms of subjectivities and new models of gender relations.
Phylogeny and biogeography of Muusoctopus (Cephalopoda: Enteroctopodidae)
Authors: Ibáñez Christian M. , Pardo‐Gandarillas María C. , Peña Fabiola , Gleadall Ian G. , Poulin Elie , Sellanes Javier
Published: March 2016

Deep‐sea octopuses of the genus Muusoctopus are thought to have originated in the Pacific Northern Hemisphere and then diversified throughout the Pacific and into the rest of the World Ocean. However, this hypothesis was inferred only from molecular divergence times. Here, the ancestral distribution and dispersal routes are estimated by Bayesian analysis based on a new phylogeny including 38 specimens from the south‐eastern Pacific Ocean. Morphological data and molecular sequences of three mitochondrial genes (16S rRNA, COI and COIII) are presented. The morphological data confirm that specimens newly acquired from off the coast of Chile comprise two species: Muusoctopus longibrachus and the poorly described species, Muusoctopus eicomar. The latter is here redescribed and is clearly distinguished from M. longibrachus and other closely related species in the region. A gene tree was built using Bayesian analysis to infer the phylogenetic position of these species within the species group, revealing that a large genetic distance separates the two sympatric Chilean species. M. longibrachus is confirmed as the sister species of Muusooctopus eureka from the Falkland Islands; while M. eicomar is a sister species of Muusoctopus yaquinae from the North Pacific, most closely related to the amphi‐Atlantic species Muusoctopus januarii. Molecular divergence times and ancestral distribution analyses suggest that genus Muusoctopus may have originated in the North Atlantic: one lineage dispersed directly southward to the Magellan region and another dispersed southward along the Eastern Pacific to the Southern Ocean and Antarctica. The Muusoctopus species in the Southern Hemisphere have different phylogenetic origins and represent independent invasions of this region.
Influence of prior hyperventilation duration on respiratory chemosensitivity and cerebrovascular reactivity during modified hyperoxic rebreathing
Authors: Boulet Lindsey M. , Tymko Michael M. , Jamieson Alenna N. , Ainslie Philip N. , Skow Rachel J. , Day Trevor A.
Published: March 2016

New Findings

What is the central question of this study?

We characterized and compared the cardiorespiratory and cerebrovascular responses to the ‘Duffin’ modified hyperoxic CO2 rebreathing test by randomly altering the prior hyperventilation duration.

What is the main finding and its importance?

Our main finding was that prior hyperventilation duration (1, 3 or 5 min) had no effect on cardiorespiratory and cerebrovascular responses to the hyperoxic rebreathing test, within individuals. These findings suggest that the standard 5 min prior hyperventilation duration used to clear body CO2 stores is unnecessary and can reasonably be shortened to 1 min, reducing protocol times and improving participant comfort.

The ‘Duffin’ modified hyperoxic rebreathing test allows investigators to characterize and quantify the ventilatory and cerebrovascular responses to CO2 across a large physiological range, allowing quantification of basal ventilation and the ventilatory recruitment threshold (VRT). Although the standard protocol includes 5 min of prior hyperventilation to clear body CO2 stores, there is no experimental evidence that a full 5 min is required. We hypothesized that there would be no within‐individual differences in the cardiorespiratory or cerebrovascular responses to rebreathing with shortened hyperventilation duration prior to hyperoxic rebreathing. Using a rebreathing apparatus, transcranial Doppler ultrasound and beat‐to‐beat blood pressure monitoring, we tested 19 participants in the supine position using three randomly assigned hyperoxic rebreathing tests with 1, 3 or 5 min of prior hyperventilation. We measured VRT (in Torr CO2), time to VRT (in seconds), central respiratory chemoreflex (breathing frequency, tidal volume and minute ventilation), cerebrovascular (middle and posterior cerebral artery velocity) and cardiovascular (heart rate and mean arterial pressure) responses to CO2 during hyperoxic rebreathing. Using linear regression and repeated‐measures ANOVAs, we found no differences in any of the cardiorespiratory or cerebrovascular response magnitudes between trials (P > 0.05). The only difference observed was in the time to VRT (in seconds), whereby 1 min prior hyperventilation duration was shorter (135.4 ± 19.7 s) than with 3 or 5 min prior hyperventilation (176.3 ± 15.1 and 187.2 ± 11.6 s, respectively; P < 0.001). Our findings indicate that 5 min of prior hyperventilation is unnecessary during modified rebreathing when using it to quantify respiratory or cerebrovascular responses and can be reasonably shortened to 1 min, reducing protocol times and improving participant comfort.
Determination of Limit Load Solution for the Remaining Load-Carrying Capacity of Corroded Pipelines
Authors: Abdel Ghani Mechri , Tewfik Ghomari , Djahida Djouadi
Published: March 2016

The evaluation of pipelines having external corrosion defect and their remaining load-carrying capacity is a concern which becomes important in energy industry, especially with the increasing operating pressures and the consequences which can occur following the bursting of these pipelines. A lower bound analytical solution for the prediction of the burst pressure of pipelines is proposed. This solution is based on the approach of plastic-instability criterion in terms of material strain-hardening exponent of internally pressurized corroded pipelines. The suggested solution is evaluated by using database comprising more than 100 carried out tests of pipelines with or without corrosion defects. This database is collected from the literature and covers the majority of steel materials as well as the various standard sizes. The accuracy of the proposed solution is compared with B31.G method and its improved version B31.G Mod by using statistical analyses in terms of average error and its correspondent standard deviation. The proposed solution is accurate than B31.G and modified B31.G methods that are conservative and provide in some cases of middle and high strength material an overestimated burst pressure predictions.
Modeling Dual–Tank Molten Salt Thermal Energy Storage Systems
Authors: Abutayeh Mohammad
Published: March 2016

Thermal energy storage systems are designed to store extra heat in order to release it at a more appropriate time. There are many industrial applications that can utilize the thermal energy storage concept, such as oil drilling and solar power generation. A model depicting the operation of a dual–tank molten salt thermal energy storage system was developed to be used to optimize its charging and discharging operations.

Thermal energy storage systems are very well insulated; nonetheless, molten salt is constantly losing small amounts of its heat to the ambient because of the large temperature gradient across the surface of the holding tanks. Consequently, auxiliary heaters are always attached to thermal energy storage systems to prevent salt freezing during extended periods of little or no thermal energy input, such as lengthy cloud cover periods in solar thermal power plants.
Development of a Response Factor Model for Thermo-Active Building Foundation
Authors: Kwag Byung Chang , Krarti Moncef
Published: March 2016

A transient three-dimensional finite difference numerical model was developed for the analysis of thermo-active foundations. The numerical model predictions were validated against experimental data obtained from laboratory testing. Using the validated 3D numerical model, a series of parameter sensitivity analyses was performed. It was found that the foundation depth, the shank space, the fluid flow rate, and thermal conductivity of ground and concrete affected the thermal performance of a thermo-active foundation system. Moreover, utilizing the numerical model, thermal response factors for thermo-active foundations were developed and implemented into a whole building energy simulation program. The thermal-response factor method was then used to estimate the effects of thermo-active foundations to reduce the energy consumption needed to condition commercial buildings.
Quantitative and Qualitative Comparison of Light Water and Advanced Small Modular Reactors (SMRs)
Authors: Aydogan Fatih
Published: March 2016

In the recent years, several Small Modular Reactors (SMRs) have been developed. These Nuclear Power Plants (NPPs) not only offer small power size (less than 300MWe), foot print, compact designs fabricated in factories to transport to the sites but also passive safety features. On one hand, some of the Light Water (LW) SMRs have been aggressively competing to win Department of Energy’s Funding Opportunity Announcements (FOA): NuScale, W-SMR, etc. These new LW-SMRs are mainly inspired by the early LW-SMRs (such as, Process Inherent Ultimate Safety (PIUS), International Reactor Innovative and Secure (IRIS), Small Innovative Reactor (SIR), etc). LW-SMRs employ significantly less number of components to decrease cost and increase simplicity. However, new physical challenges appeared with these changes. On the other hand, advanced SMRs (such as, PBMR, MHR Antares, Prism, 4S, Hyperion, etc.) are dazzled with their improved passive safety features. This paper compares most of the LW and Advanced SMRs in respect to reactors, nuclear fuel, containment, reactor coolant systems, re-fueling and emergency coolant systems quantitatively and qualitatively. The detailed comparisons in this paper show that one reactor is not the absolute winner in this comparison since each reactor is designed to meet different needs.
Effects of the Foil Flatness on the Stress-Strain Characteristics of U10Mo Alloy Based Monolithic Mini-Plates
Authors: Ozaltun Hakan , Medvedev Pavel
Published: March 2016

The effects of the foil flatness on stress-strain behavior of monolithic fuel mini-plates during fabrication and irradiation were studied. Monolithic plate-type fuels are a new fuel form being developed for research and test reactors to achieve higher uranium densities. This concept facilitates the use of low-enriched uranium fuel in the reactor. These fuel elements are comprised of a high density, low enrichment, U–Mo alloy based fuel foil encapsulated in a cladding material made of Aluminum.

To evaluate the effects of the foil flatness on the stress-strain behavior of the plates during fabrication, irradiation and shutdown stages, a representative plate from RERTR-12 experiments (Plate L1P756) was considered. Both fabrication and irradiation processes of the plate were simulated by using actual irradiation parameters. The simulations were repeated for various foil curvatures to observe the effects of the foil flatness on the peak stress and strain magnitudes of the fuel elements.

Results of fabrication simulations revealed that the flatness of the foil does not have a considerable impact on the post fabrication stress-strain fields. Furthermore, the irradiation simulations indicated that any post-fabrication stresses in the foil would be relieved relatively fast in the reactor. While, the perfectly flat foil provided the slightly better mechanical performance, overall difference between the flat-foil case and curved-foil case was not significant. Even though the peak stresses are less affected, the foil curvature has several implications on the strain magnitudes in the cladding. It was observed that with an increasing foil curvature, there is a slight increase in the cladding strains.
Vacuum Cavity Parabolic Trough Collector
Authors: Gharbia Yousef , Grami Said , Wazwaz Aref
Published: March 2016

Without frequent cleaning, dust accumulation on parabolic trough collectors can lead to significant degradation of the performance of trough collectors over time. Owing to the nature of the trough profile and the presence of the receiving tube in the middle of the trough, automatic cleaning has not been a feasible option. The problem of dust accumulation is of particular interest in the Middle East/North African (MENA) region with the high frequency of dusty days throughout the year. This paper presents a thermal numerical analysis of a novel vacuum cavity parabolic trough collector (VCPTC) in which the top and the sides of the trough were covered with borosilicate sheets and a vacuum was assumed inside the cavity. The typical vacuum tube used in conventional troughs was replaced by a bare stainless steel pipe with selective coating. The new trough with its flat top surface should now be much easier to clean with an automatic cleaning machine. This paper compares the performance of a conventional trough with the new VCPTC in terms of overall heat loss. The results have shown that the VCPTC has slightly outperformed the conventional trough.
Experimental Studies of Rotation Efficiency of Packing on Characteristics of Counter Flow Wet Cooling Tower
Authors: Teimoori Khashayar , Sadegh Ali M.
Published: March 2016

Packing in cooling towers is commonly used in nuclear power plants and air conditioning systems. However their efficiency with respect to the inlet air flow rate and the temperature of the water has not been fully investigated. In this research, the efficiency of packing rotational speed with respect to the wet counter flow of a cooling tower is experimentally investigated. In our experimental studies, six elliptical wooden plates that are equally spaced are used as a packing tower. The packing area of 0.85 m2 is considered with the following rotor speed ranges: 0.5, 3.5, 10, 15 and 17 rpm. It is assumed that the water mass flow rate is proportional to the inlet air to the tower. Six mass flow rates starting from 0.2 to 2.8 kg/h and the inlet air and water temperatures of 27°C and 45°C, respectively, are considered. The results illustrate that for the range of 0 to 5 rpm of the packing rotational speed the cooling rate of water is increased 3% for the water flow rate of 2.8 kg/h, and 24% for the water flow rate of 0.4 kg/h.

Additionally, as a result of the increased rotational speed from 5 to over 17 rpm the cooling rate at both maximum and minimum water mass flow rates are increased from 13.9 to 34.4 percent, respectively. Furthermore, the water outlet temperature is reduced from 8.6°C to 3.3°C in the least and the most mass flow rates leading to the increased speed from 5 to 17 rpm, respectively. The experimental relationship between the inlet air temperature and the rotational speed of the packing has been determined. Also, the inlet water temperature at the maximum flow rate has been decreased to 3.4 and at the least water mass flow rate it has been decreased to 29 percent for the range of rotational speed from 5 to over 17 rpm of the packing rotation. All the results are depicted in several curves to show the actual variations of the variables.
Mathematical Model of a Hybrid Solar Panel
Authors: Collins Robert P. , Gutierrez-Miravete Ernesto
Published: March 2016

Hybrid solar panels are energy conversion devices that combine photovoltaic cells with an efficient heat exchanger. By circulating a cold liquid underneath a PV cell module array, the array is cooled, increasing its energy conversion efficiency, while also recovering excess heat. This paper describes finite element modeling work designed to investigate the increased collection efficiency that is possible when using hybrid solid panels. The model simulates fluid flow, heat transfer and energy conversion in a two-dimensional configuration with heat exchangers consisting of two parallel plates with and without fins. Results show that the fraction of the solar energy recovered is significantly higher when the heat exchanger is attached to the PV module array to produce the hybrid solar panel.
High Temperature Thermal Energy Storage Using EPCM: The Effect of Void
Authors: Solomon Laura , Elmozughi Ali F. , Neti Sudhakar , Oztekin Alparslan
Published: March 2016

Heat transfer simulations and predictions of the thermal energy storage capability using encapsulated phase change materials (EPCM) at high temperatures are conducted. NaNO3 is considered as a phase change material (PCM). The PCM is encapsulated by a stainless steel shell. Two dimensional simulations of a cylindrical capsule are considered. The effects of the buoyancy driven convection in the molten PCM as well as the thermal and volume expansions due to phase change are included in the thermal analysis. An initial void level of 20% is considered in the simulations of the EPCM capsules. EPCM capsules store energy not only by sensible heat but also by the latent heat of fusion as heat is stored or extracted from the capsule. The solid/liquid interface inside the PCM propagates radially inward during the melting process. The effect of a void on the thermal energy storage and on the evolution of the solid/liquid interface is characterized. Two cases are presented, that of a local void initially at the top of the EPCM capsule and an initially random void distribution. The initial location of the void within the capsule has a profound effect on the shape of the solid/liquid interface and the isotherms within the capsule. The results of these simulations can be the basis for the design of an EPCM based thermocline for thermal energy storage (TES) at a concentrated solar power plant and other applications.
Comparative Analysis Between Water and Nanofluids as Working Fluids in Photovoltaic Thermal Collectors
Authors: Abdel-Mesih Bahy S. A. , Abdelrehim Ahmed A. , Khobeiz Amr M. H.
Published: March 2016

Photovoltaic thermal collectors (PV/T) are devices that produce both electrical and thermal energies simultaneously. Water acts as the working fluid that cools down the PV cells, thus improving their electrical efficiency, and at the same time hot water is produced due to the heat exchange process. As a consequence heat transfer augmentation is an important issue that affects the performance of such a hybrid system. The objective of the current study is to evaluate the effect of using a nanofluid on the performance of a photovoltaic thermal (PV/T) collector. The performance of the water cooled PV/T collector without nanofluid is first evaluated and then additional correlations are incorporated to include the nanofluid properties. Results showed that the use of nanofluid enhanced the rate of heat transfer which resulted in improvement in the performance of the PV/T collector. However, such improvement was not found to be significantly high to shift for nanofluids as working fluids in PV/T collectors.
Fuel Assembly Bowing and Core Restraint Design in Fast Reactors
Authors: Grudzinski J. J. , Grandy C.
Published: March 2016

The reactivity of a fast spectrum nuclear reactor core is sensitive to changes in the fuel position. The core is formed by a hexagonal array of fuel assemblies which contain the fuel elements. The main structural components of the assemblies are thinwall hexagonal ducts. The fuel elements represent negligible stiffness in the fuel assembly compared to the ducts such that the ducts determine the location of the fuel. Thermal gradients across the fuel assembly cross sections create differential thermal expansion which causes the assemblies to bow. This bowing is proportional to the power to flow ratio such that it can become an important part of the reactivity change during reactor transients such as during reactor start-up, transient overpower (TOP), and unprotected loss of flow without scram (ULOF). In addition to these short term transients, thermal and fast neutron flux gradients within the core cause the assembly ducts to swell and bow over time due to irradiation creep and swelling. These latter effects produce permanent bowing of the ducts which change the reactivity over time and more importantly affect the mechanical forces required to refuel the core as the bowing is greater that the duct-to-duct clearance. Understanding these bowing responses is important to the understanding of both the transient behavior of a fast reactor as well as the refueling loads. Through proper design of the core restraint system, the bowing response can be engineered to provide negative feedback during the above mentioned transients such that it becomes part of the inherent safety of a fast reactor. Similarly, the opposing effects of creep and swelling can be manipulated to reduce the permanent core bowing deformations. We provide a discussion of the key features of analyzing and designing a core restraint system and provide a brief survey of the past work.
Thermal Assessment of a Latent Heat Energy Storage Module Using a High Temperature Phase Change Material With Enhanced Radiative Properties
Authors: Archibold Antonio Ramos , Bhardwaj Abhinav , Rahman Muhammad M. , Goswami D. Yogi , Stefanakos Elias L.
Published: March 2016

This paper presents a comprehensive analysis of the heat transfer during the melting process of a high temperature (> 800°C) PCM encapsulated in a vertical cylindrical container. The energy contributions from radiation, natural convection and conduction have been included in the mathematical model in order to capture most of the physics that describe and characterize the problem and quantify the role that each mechanism plays during the phase change process. Numerical predictions based on the finite volume method has been obtained by solving the mass, momentum and energy conservation principles along with the enthalpy porosity method to track the liquid/solid interface. Experiments were conducted to obtain the temperature response of the TES-cell during the sensible heating and phase change regions of the PCM. Continuous temperature measurements of porcelain crucibles filled with ACS grade NaCl were recorded. The temperature readings were recorded at the center of the sample and at the wall of the crucible as the samples were heated in a furnace over a temperature range of 700 °C to 850 °C. The numerical predictions have been validated by the experimental results and the effect of the controlling parameters of the system on the melt fraction rate, total and radiative heat transfer rates at the inner surface of the cell have been evaluated. Results showed that the natural convection is the dominant heat transfer mechanism. In all the experimental study cases, the measured temperature response captures the PCM melting trends with acceptable repeatability. The uncertainty analysis of the experiment yielded an approximate error of ±5.81°C.
Simulation of a High-Temperature Modular Reactor (HTMR) for Power and Coal-to-Liquid Fuel-Cogeneration Plant
Authors: Tshamala Mubenga Carl , Dobson Robert T.
Published: March 2016

Traditionally nuclear reactor power plants have been optimized for electrical power generation only. In the light of the ever-rising cost of ever-dwindling fossil fuel resources as well the global polluting effects and consequences of their usage, the use of nuclear energy for process heating is becoming increasingly attractive. In this study the use of a so-called cogeneration plant in which a nuclear reactor energy source is simulated using basic equations for the simultaneous production of superheated steam for electrical power generation and process heat, is considered and analyzed. A novel heat pipe heat exchanger is used to generate superheated steam for the process heat which is, in this case, a coal-to-liquid process (CTL). Natural circulation of sodium, via a thermo-syphon, is used in the heat pipe heat exchanger to transfer heat from the hot stream to the cold. The superheated steam for power generation is generated in a separate once-through helical coil steam generator. A 750 °C, 7 MPa helium cooled high-temperature modular reactor (HTMR) has been considered to simultaneously provide steam at 540 °C, 13.5 MPa for the power unit and steam at 430 °C, 4 MPa for a CTL production plant. The simulation and dynamic control of such a cogeneration plant is considered. In particular, a theoretical model of the plant will be simulated with the aim of predicting the transient and dynamic behavior of the HTMR in order to provide guideline for the control of the plant under various operating conditions. It was found that the simulation model captured the behavior of the plant reasonably well and it is recommended that it could be used in the detailed design of plant control strategies. It was also found that using a 1500 MW-thermal HTMR the South African contribution to global pollution can be reduced by 1.58%.
Designing and Installing a Retrofit Heated Green Roof Using Either Co-Gen Waste Hot Water or Municipal Waste Steam Heat as Energy Source
Authors: Dell Robert , Wei C. S. , Parikh Raj , Unnthorsson Runar , Foley William
Published: March 2016

Municipal District Heating Services and Combined Heat and Power (CHP) systems can produce waste heat in the form of steam condensate and hot water. The authors have developed a system to use this thermal pollution to heat the soil and growth medium of green roofs and outdoor gardens. The system enables plant life to survive colder climates and increases growth often in excess of 20% (Power2013-98172). In New York City test heated green roofs, the system can save vast amounts of normally required cooling water that is tapped from the overburdened municipal supply (IMECE2013-65200).

Existing small scale green roofs in New York City and larger scale heated green roof retrofit in New York City is presented to indicate additional construction details, thermal considerations, and potential code compliance considerations.
Magnetically Assembling Nanoscale Metal Network Into Phase Change Material
Authors: Su Junwei , Liu Xiao , Mirzaee Iman , Gao Fan , Charmchi Majid , Gu Zhiyong , Sun Hongwei
Published: March 2016

A high throughput manufacturing process to magnetically assembling nanowire (NW) network into paraffin was developed for enhancing conductivity in phase change materials (PCMs) used in energy storage applications. The prefabricated nickel nanowires were dispersed in melted paraffin followed by magnetic alignment under a strong magnetic field. Measuring electrical conductivity of the nanocomposites, as well as observing cross-section of the sample slice under an optical microscope characterized the alignment of nanowires. As a comparison, nickel particles (NPs) based paraffin nanocomposites were also fabricated and its electrical conductivity with and without applied magnetic field were measured. The effects of aspect ratio of fillers (particles and nanowires) and volume concentration on percolation threshold were studied both experimentally and theoretically. It was found that the nanowire based paraffin nanocomposite has much lower percolation threshold compared to that of particle based paraffin composite. Furthermore, the alignment of particles and nanowires under magnetic field significantly reduce the threshold of percolation. This work provides solid foundation for the development of a manufacturing technology for high thermal conductivity phase change materials (PCM) for thermal energy storage applications.