bluuebunny/crossref_metadata_2025 huggingface dataset:
Co‐incorporation of biodegradable wastes with crop residues to reduce nitrate pollution of groundwater and decrease waste disposal to landfill
Authors: Rahn C. R. , Bending G. D. , Lillywhite R. D. , Turner M. K.
Published: April 2009

Return of high nitrogen (N) content crop residues to soil, particularly in autumn, can result in environmental pollution resulting from gaseous and leaching losses of N. The EU Landfill Directive will require significant reductions in the amounts of biodegradable materials going to landfill. A field experiment was set up to examine the potential of using biodegradable waste materials to manipulate losses of N from high N crop residues in the soil. Leafy residues of sugar beet were co‐incorporated into soil with materials of varying C:N ratios, including molasses, compactor waste, paper waste, green waste compost and cereal straw. The amendment materials were each incorporated to provide approximately 3.7 t C per hectare. The most effective material for reducing nitrous oxide (N2O) production and leaching loss of NO3− was compactor waste, which is the final product from the recycling of cardboard. Adding molasses increased N2O and NO3− leaching losses. Six months following incorporation of residues, the double rate application of compactor waste decreased soil mineral N by 36 kg N per hectare, and the molasses increased soil mineral N by 47 kg N per hectare. Compactor waste reduced spring barley grain yield by 73% in the first of years following incorporation, with smaller losses at the second harvest. At the first harvest, molasses and paper waste increased yields of spring barley by 20 and 10% compared with sugar beet residues alone, and the enhanced yield persisted to the second harvest. The amounts of soil mineral N in the spring and subsequent yields of a first cereal crop were significantly correlated to the lignin and cellulose contents of the amendment materials. Yield was reduced by 0.3–0.4 t/ha for every 100 mg/g increase in cellulose or lignin content. In a second year, cereal yield was still reduced and related to the cellulose content of the amendment materials but with one quarter of the effect. Additional fertilizer applied to this second crop did not relieve this effect. Although amendment materials were promising as tools to reduce N losses, further work is needed to reduce the negative effects on subsequent crops which was not removed by applying 60 kg/ha of fertilizer N.
Polyacrylate polymers as immobilizing agents to aid phytostabilization of two mine soils
Authors: De Varennes A. , Cunha‐Queda C. , Ramos A. R.
Published: April 2009

We evaluated the effect of polyacrylate polymers as immobilizing agents to aid phytostabilization of two mine soils. One soil had a very low pH (3.7) and a large Pb content, while the other was less acidic but had a greater content of Cu and Zn. Growth of perennial ryegrass (Lolium perenne L. cv. Victorian) was stimulated in polymer‐amended soils. After ryegrass had been growing for 35 days, the amounts of water‐extractable Cu, Zn and Pb (one soil only) present in the polymer‐amended soils were smaller than those from soil without polymer. The number of culturable heterotrophic bacteria and the activities of dehydrogenase and β‐glucosidase increased following polymer application. In contrast, the urease activity was impaired by polymer application, presumably because of the presence of ammonium as a counter ion. In another experiment, the acidic soil was limed to pH 6.5 before growth of perennial ryegrass took place. Liming the soil greatly enhanced plant growth, but by the third cut, differences between treatments became apparent, with plants from polymer‐amended limed soil accumulating a greater biomass compared with limed soil without polymer. After ryegrass had been growing for 119 days (five cuts), the amount of water‐extractable Pb and the urease activity in the polymer‐amended soil were smaller than those from limed soil without polymer. The numbers of culturable heterotrophic bacteria and the activities of dehydrogenase, β‐glucosidase and acid phosphatase increased following polymer application. The results are consistent with phytostabilization being achieved by the application of polyacrylate polymers, improving soil chemical and biological properties. In very acidic soils, the use of both a liming material and polymer together appears to give a considerable advantage.
Marked changes in signal transduction upon heteromerization of dopamine D1 and histamine H3 receptors
Authors: Ferrada Carla , Moreno Estefanía , Casadó Vicent , Bongers Gerold , Cortés Antoni , Mallol Josefa , Canela Enric I , Leurs Rob , Ferré Sergi , Lluís Carme , Franco Rafael
Published: April 2009

Background and purpose:  Functional interactions between the G protein‐coupled dopamine D1 and histamine H3 receptors have been described in the brain. In the present study we investigated the existence of D1–H3 receptor heteromers and their biochemical characteristics.

Experimental approach:  D1–H3 receptor heteromerization was studied in mammalian transfected cells with Bioluminescence Resonance Energy Transfer and binding assays. Furthermore, signalling through mitogen‐activated protein kinase (MAPK) and adenylyl cyclase pathways was studied in co‐transfected cells and compared with cells transfected with either D1 or H3 receptors.

Key results:  Bioluminescence Resonance Energy Transfer and binding assays confirmed that D1 and H3 receptors can heteromerize. Activation of histamine H3 receptors did not lead to signalling towards the MAPK pathway unless dopamine D1 receptors were co‐expressed. Also, dopamine D1 receptors, usually coupled to Gs proteins and leading to increases in cAMP, did not couple to Gs but to Gi in co‐transfected cells. Furthermore, signalling via each receptor was blocked not only by a selective antagonist but also by an antagonist of the partner receptor.

Conclusions and implications:  D1–H3 receptor heteromers constitute unique devices that can direct dopaminergic and histaminergic signalling towards the MAPK pathway in a Gs‐independent and Gi‐dependent manner. An antagonist of one of the receptor units in the D1–H3 receptor heteromer can induce conformational changes in the other receptor unit and block specific signals originating in the heteromer. This gives rise to unsuspected therapeutic potentials for G protein‐coupled receptor antagonists.
Pharmacological characterization of the new histamine H4receptor agonist VUF 8430
Authors: Lim Herman D , Adami Maristella , Guaita Elena , Werfel Thomas , Smits Rogier A , De Esch Iwan JP , Bakker Remko A , Gutzmer Ralf , Coruzzi Gabriella , Leurs Rob
Published: April 2009

Background and purpose: We compare the pharmacological profiles of a new histamine H4receptor agonist 2‐(2‐guanidinoethyl)isothiourea (VUF 8430) with that of a previously described H4receptor agonist, 4‐methylhistamine.

Experimental approach: Radioligand binding and functional assays were performed using histamine H4receptors expressed in mammalian cell lines. Compounds were also evaluatedex vivoin monocyte‐derived dendritic cells endogenously expressing H4receptors andin vivoin anaesthetized rats for gastric acid secretion activity.

Key results: Both VUF 8430 and 4‐methylhistamine were full agonists at human H4receptors with lower affinity at rat and mouse H4receptors. Both compounds induced chemotaxis of monocyte‐derived dendritic cells. VUF 8430 also showed reasonable affinity and was a full agonist at the H3receptor. Agmatine is a metabolite of arginine, structurally related to VUF 8430, and was a H4receptor agonist with micromolar affinity. At histamine H3receptors, agmatine was a full agonist, whereas 4‐methylhistamine was an agonist only at high concentrations. Both VUF 8430 and agmatine were inactive at H1and H2receptors, whereas 4‐methylhistamine is as active as histamine at H2receptors.In vivo,VUF 8430 only caused a weak secretion of gastric acid mediated by H2receptors, whereas 4‐methylhistamine, dimaprit, histamine and amthamine, at equimolar doses, induced 2.5‐ to 6‐fold higher output than VUF 8430.

Conclusions and implications: Our results suggest complementary use of 4‐methylhistamine and VUF 8430 as H4receptor agonists. Along with H4receptor antagonists, both agonists can serve as useful pharmacological tools in studies of histamine H4receptors.
Effects of L‐histidine depletion and L‐tyrosine/L‐phenylalanine depletion on sensory and motor processes in healthy volunteers
Authors: Van Ruitenbeek P , Sambeth A , Vermeeren A , Young SN , Riedel WJ
Published: April 2009

Background and purpose:  Animal studies show that histamine plays a role in cognitive functioning and that histamine H3‐receptor antagonists, which increase histaminergic function through presynaptic receptors, improve cognitive performance in models of clinical cognitive deficits. In order to test such new drugs in humans, a model for cognitive impairments induced by low histaminergic functions would be useful. Studies with histamine H1‐receptor antagonists have shown limitations as a model. Here we evaluated whether depletion of L‐histidine, the precursor of histamine, was effective in altering measures associated with histamine in humans and the behavioural and electrophysiological (event‐related‐potentials) effects.

Experimental approach:  Seventeen healthy volunteers completed a three‐way, double‐blind, crossover study with L‐histidine depletion, L‐tyrosine/L‐phenylalanine depletion (active control) and placebo as treatments. Interactions with task manipulations in a choice reaction time task were studied. Task demands were increased using visual stimulus degradation and increased response complexity. In addition, subjective and objective measures of sedation and critical tracking task performance were assessed.

Key results:  Measures of sedation and critical tracking task performance were not affected by treatment. L‐histidine depletion was effective and enlarged the effect of response complexity as measured with the response‐locked lateralized readiness potential onset latency.

Conclusions and implications:  L‐histidine depletion affected response‐ but not stimulus‐related processes, in contrast to the effects of H1‐receptor antagonists which were previously found to affect primarily stimulus‐related processes. L‐histidine depletion is promising as a model for histamine‐based cognitive impairment. However, these effects need to be confirmed by further studies.
Structural features of mammalian histidine decarboxylase reveal the basis for specific inhibition
Authors: Moya‐García AA , Pino‐Ángeles A , Gil‐Redondo R , Morreale A , Sánchez‐Jiménez F
Published: April 2009

For a long time the structural and molecular features of mammalian histidine decarboxylase (EC 4.1.1.22), the enzyme that produces histamine, have evaded characterization. We overcome the experimental problems for the study of this enzyme by using a computer‐based modelling and simulation approach, and have now the conditions to use histidine decarboxylase as a target in histamine pharmacology. In this review, we present the recent (last 5 years) advances in the structure–function relationship of histidine decarboxylase and the strategy for the discovery of new drugs.
Use of the H3receptor antagonist radioligand [3H]‐A‐349821 to revealin vivoreceptor occupancy of cognition enhancing H3receptor antagonists
Authors: Miller TR , Milicic I , Bauch J , Du J , Surber B , Browman KE , Marsh K , Cowart M , Brioni JD , Esbenshade TA
Published: April 2009

Background and purpose: The histamine H3receptor antagonist radioligand [3H]‐A‐349821 was characterized as a radiotracer for assessingin vivoreceptor occupancy by H3receptor antagonists that affect behaviour. This model was established as an alternative toex vivobinding methods, for relating antagonist H3receptor occupancy to blood levels and efficacy in preclinical models.

Experimental approach: In vivocerebral cortical H3receptor occupancy by [3H]‐A‐349821 was determined in rats from differences in [3H]‐A‐349821 levels in the isolated cortex and cerebellum, a brain region with low levels of H3receptors. Comparisons were made to relate antagonist H3receptor occupancy to blood levels and efficacy in a preclinical model of cognition, the five‐trial inhibitory avoidance response in rat pups.

Key results: In adult rats, [3H]‐A‐349821, 1.5 µg·kg−1, penetrated into the brain and cleared more rapidly from cerebellum than cortex; optimally, [3H]‐A‐349821 levels were twofold higher in the latter. With increasing [3H]‐A‐349821 doses, cortical H3receptor occupancy was saturable with a binding capacity consistent within vitrobinding in cortex membranes. In studies using tracer [3H]‐A‐349821 doses, ABT‐239 and other H3receptor antagonists inhibited H3receptor occupancy by [3H]‐A‐349821 in a dose‐dependent manner. Blood levels of the antagonists corresponding to H3receptor occupancy were consistent with blood levels associated with efficacy in the five‐trial inhibitory avoidance response.

Conclusions and implications: When employed as an occupancy radiotracer, [3H]‐A‐349821 provided valid measurements ofin vivoH3receptor occupancy, which may be helpful in guiding and interpreting clinical studies of H3receptor antagonists.
Molecular and biochemical pharmacology of the histamine H4receptor
Authors: Leurs Rob , Chazot Paul L , Shenton Fiona C , Lim Herman D , De Esch Iwan JP
Published: April 2009

The elucidation of the human genome has had a major impact on histamine receptor research. The identification of the human H4receptor by several groups has been instrumental for a new appreciation of the role of histamine in the modulation of immune function. In this review, we summarize the historical developments and the molecular and biochemical pharmacology of the H4receptor.
Analysis of Left Ventricular Regional Dyssynchrony: Comparison between Real Time 3D Echocardiography and Tissue Doppler Imaging
Authors: Vieira Marcelo L. C. , Cury Alexandre F. , Naccarato Gustavo , Oliveira Wercules A. , Mônaco Cláudia G. , Rodrigues Ana C. T. , Cordovil Adriana , Tavares Gláucia M. P. , Filho Edgar B. Lira , Pfeferman Abraham , Fischer Cláudio H. , Morhy Samira S.
Published: April 2009

Background: There is a paucity of information concerning left ventricular (LV) dyssynchrony assessment by real time three‐dimensional (3D) echocardiography (RT3DE) versus tissue Doppler imaging (TDI). Aims: To compare RT3DE and TDI LV dyssynchrony assessment. Methods: A prospective study of 92 individuals (56 men, age 47 ± 10 years), 32 with dilated cardiomyopathy (CMP), and 60 healthy individuals. By RT3DE, we measured the LV% dyssynchrony index (DI) of 6, 12, and 16 segments (SDI). By pulsed‐wave TDI, we measured the QS electromechanical interval in the basal segments of the mitral valve annulus of the septum, the lateral, anterior and inferior walls, and the TDI% DI. Results: In the normal group, the 3D DI was 1.1 ± 0.8%, 1.4 ± 1.3%, 1.8 ± 1.7%, for 6 segments, 12 segments, and SDI, respectively. The correlation coefficient (Pearson's r) for the TDI DI and SDI was r = 0.2381 (P = 0.0470). In CMP group, the 3D DI was 4.6 ± 5.4%, 7.9 ± 7.1%, 11.1 ± 7.1%, for 6 segments, 12 segments, and SDI, respectively. The correlation coefficient for TDI DI and SDI was r = 0.7838 (P < 0.0001). Conclusions: We observed a good correlation between RT3DE and tissue Doppler LV dyssynchrony assessment in patients with advanced heart failure. (ECHOCARDIOGRAPHY, Volume 26, July 2009)
Molecular Phylogeny of the Ocelloid‐Bearing Dinoflagellates Erythropsidinium and Warnowia (Warnowiaceae, Dinophyceae)
Authors: GÓMEZ FERNANDO , LÓPEZ‐GARCÍA PURIFICACIÓN , MOREIRA DAVID
Published: April 2009

ABSTRACT. Members of the family Warnowiaceae are unarmored phagotrophic dinoflagellates that possess an ocelloid. The genus Erythropsidinium (=Erythropsis) has also developed a unique dynamic appendage, the piston, which is able to independently retract and extend for at least 2 min after the cell lyses. We provide the first small subunit ribosomal RNA gene sequences of warnowiid dinoflagellates, those of the type Erythropsidinium agile and one species of Warnowia. Phylogenetic analyses show that warnowiid dinoflagellates branch within the Gymnodinium sensu stricto group, forming a cluster separated from the Polykrikos clade and with autotrophic Pheopolykrikos beauchampii as closest relative. This reinforces their classification as unarmored dinoflagellates based on the shape of the apical groove, despite the strong ecological and ultrastructural diversity of the Gymnodinium s.s. group. Other structures, such as the ocelloid and piston, have no systematic value above the genus level.
Molecular Phylogeny and Surface Morphology of Marine Archigregarines (Apicomplexa), Selenidium spp., Filipodium phascolosomae n. sp., and Platyproteum n. g. and comb. from North‐Eastern Pacific Peanut Worms (Sipuncula)
Authors: RUECKERT SONJA , LEANDER BRIAN S.
Published: April 2009

ABSTRACT. The trophozoites of two novel archigregarines, Selenidium pisinnus n. sp. and Filipodium phascolosomae n. sp., were described from the sipunculid Phascolosoma agassizii. The trophozoites of S. pisinnus n. sp. were relatively small (64–100 μm long and 9–25 μm wide), had rounded ends, and had about 21 epicytic folds per side. The trophozoites of F. phascolosomae n. sp. were highly irregular in shape and possessed hair‐like surface projections. The trophozoites of this species were 85–142 μm long and 40–72 μm wide and possessed a distinct longitudinal ridge that extended from the mucron to the posterior end of the cell. In addition to the small subunit (SSU) rDNA sequences of these two species, we also characterized the surface morphology and SSU rDNA sequence of Selenidium orientale, isolated from the sipunculid Themiste pyroides. Molecular phylogenetic analyses demonstrated that S. pisinnus n. sp. and S. orientale formed a strongly supported clade within other Selenidium and archigregarine‐like environmental sequences. Filipodium phascolosomae n. sp. formed the nearest sister lineage to the dynamic, tape‐like gregarine Selenidium vivax. Overall, these data enabled us to reassess the molecular systematics of archigregarines within sipunculid hosts and make the following revisions: (1) Filipodium was transferred from the Lecudinidae (eugregarines) to the Selenidiidae (archigregarines), and (2) Platyproteum n. g. was established for Platyproteum vivax n. comb. (ex. S. vivax) in order to account for the highly divergent morphological features and better resolved phylogenetic position of this lineage.
Abundance and habitat segregation in Mediterranean grassland species: the importance of seed weight
Authors: Azcárate F.M. , Sánchez A.M. , Arqueros L. , Peco B.
Published: April 2009

Abstract.We analysed the relationship between seed traits (weight, shape and dispersal structures) and the abundance and habitat segregation of Mediterranean grassland species. To take into account possible correlations with other plant traits, the study also includes 5 vegetative traits (growth form, plant longevity, clonality, onset of flowering and plant size) of commonly accepted functional importance. Data were recorded for 85 species fromdehesagrasslands in central Spain. Species abundance was measured in upper (dry and less productive, high stress) and lower (moist and more productive, low stress) slope zones in the same area. Habitat segregation was estimated using an index based on the relative frequencies of species in upper and lower slope zones. Multiple regression models were fitted using species, as well as phylogenetically independent contrasts, as data points. Annual small‐seeded species without specialised dispersal structures are over‐represented indehesagrasslands. Abundance was negatively related to seed weight in upper slope zones. None of the recorded plant traits were related to abundance in the lower slope zones. Habitat segregation was mainly related to seed weight, but also to some vegetative traits. Annual, early flowering and small‐seeded species were relatively more abundant in the upper than the lower slope zones. This pattern is independent of phylogeny. Our results suggest that in dry Mediterranean grasslands, abundance of many species is determined by dispersal (production of numerous small seeds) rather than by competitive ability.
The Apparent Contact Dimension and Covariates among Orthodontically Treated and Nontreated Subjects
Authors: RAJ VISHNU , HEYMANN HARALD O. , HERSHEY H. GARLAND , RITTER ANDRE V. , CASKO JOHN S.
Published: April 2009

The apparent contact dimension (ACD), a determinant of dental esthetics, has been purported to exhibit an esthetic relationship termed the “50:40:30” rule, implying that in an esthetic smile, the ACD between the central incisors, central and lateral incisors, and lateral incisor and canine would be 50, 40, and 30% of the height of a central incisor, respectively. This study assessed the existence of this proportion using casts of orthodontically treated (N = 40) and nontreated (N = 27) subjects deemed to possess excellent occlusion. Covariates studied included tooth size, tooth shape, tip, and torque. The average ACD proportions in this study, relative to the height of an ipsilateral central incisor, were found to be 49, 38, and 27% between the central incisors, central and lateral incisors, and the lateral incisor and canine, respectively. The ACD exhibited a positive correlation (p < 0.05) with the height of the clinical crown and a negative correlation (p < 0.05) with the width/height ratios of the corresponding teeth. No statistically significant correlations were evident between the ACD with the shape of the clinical crown, tip, and torque. However, the tip and torque did exhibit a statistically significant (p < 0.05) correlation with the height of the clinical crown. This study is the first to validate the existence and proportions of the ACD.

CLINICAL SIGNIFICANCE

This study validates the existence of the ACD and quantifies the relationship of the ACD with tooth size, tooth shape, mesiodistal crown angulation (tip), and labiolingual crown inclination (torque) among subjects deemed to possess excellent occlusion and alignment. This quantifiable “ideal” and its correlation with the other determinants of dental esthetics may be used in conjunction with various evidence‐based paradigms in the esthetic appraisal of the maxillary anterior teeth.
Business Group Performance in China: Ownership and Temporal Considerations
Authors: Carney Michael , Shapiro Daniel , Tang Yao
Published: April 2009

We address the institutional voids hypothesis, which suggests affiliation with a business group will improve a firm's performance in circumstances of poor-quality institutions and extensive market failures. We hypothesize that initial positive effects of group affiliation should decline as the quality of market institutions improves. Further, we hypothesize that differences in state and private ownership will influence the value and persistence of firm affiliation. Using data on 476 publicly listed firms in 1999 and 467 matched firms in 2004, we find support for a temporal hypothesis that affiliation with a business group improves performance, but the value of group affiliation declines over time. We also find support for a state ‘helping hand’ hypothesis that suggests firms with high levels of state ownership initially experienced an amplified value effect from their group affiliation, which disappeared by 2004. The results suggest that China's policy makers are beginning to establish an institutional and market infrastructure that is conducive to entry by unaffiliated, freestanding firms.
Impact of ageing and drug consumption on oral health
Authors: Gueiros Luiz Alcino , Soares Maria Sueli Marques , Leão Jair Carneiro
Published: April 2009

The impact of ageing on oral health and salivary flow is usually over‐estimated possibly because of the high frequency of polypharmacy observed in this subset of patients. Understanding the physiological changes and treatment‐related oral complications of older patients is essential to promote accurate management of symptoms and improve their quality of life. The current paper reviews age‐related physiological chances in salivary glands and the effect of polypharmacy on oral health, focusing on xerostomia and hyposalivation.
Police officers' perceptual distortions during lethal force situations: Informing the reasonableness standard*
Authors: Klinger David A. , Brunson Rod K.
Published: April 2009

Research Summary

In 1989, the U.S. Supreme Court held that determinations about the constitutional appropriateness of police force usage—deadly or not—must be “judged from the perspective of a reasonable officer on the scene, rather than with the 20/20 vision of hindsight.” Although the Court's ruling established a clear standard for judging officers' actions (i.e., the perspective of a reasonable police officer on the scene), we know little about the sorts of factors that might frame the perspective of reasonable police officers during situations in which they apply force. This article presents the results of a study that examined 80 police officers' detailed accounts of how they perceived what transpired during 113 incidents in which they shot citizens. Respondents reported experiencing a wide range of sensory distortions, with the vast majority of officers reporting two or more distinct sorts. This study takes these findings as a point of departure to expand our understanding of what constitutes a reasonable officer's perspective during the tense, uncertain moments during which he or she makes the decision to employ deadly force.

Policy Implications

Given that officers are likely to experience multiple distortions during shootings, the findings have implications for civilian and police oversight policies. In particular, those responsible for reviewing police shooting incidents should take into consideration that officers' behavior will not always be based on the objective reality of what is occurring at the time they decide to pull the trigger, but rather an altered conception of it. Such an understanding is crucial to improving the image of police in certain communities and positively impacting citizen trust of, and satisfaction with, the police.
Characterization of eight polymorphic microsatellite loci for the leopard coralgrouper (Plectropomus leopardus Lacepède)
Authors: DING SHAO‐XIONG , ZENG HUA‐SONG , WANG YING , PAN YING , SHI XIAO‐FENG
Published: April 2009

Eight polymorphic microsatellite loci were isolated and characterized from a microsatellite DNA‐enriched DNA library for the leopard coralgrouper (Plectropomus leopardus Lacepède, 1802), a popular food fish in the East Indies. These loci showed polymorphism information content ranging from 0.493 to 0.854, allele numbers ranging from 3 to 10, effective allele numbers ranging from 2.2 to 7.6, and observed and expected heterozygosities from 0.375 to 0.906 and 0.544 to 0.868 respectively. Thus, we expect that these markers will be useful for population genetic and breeding studies of the leopard coralgrouper.
Plukenetia huayllabambana sp. nov. (Euphorbiaceae) from the upper Amazon of Peru
Authors: Bussmann Rainer W. , Téllez Carolina , Glenn Ashley
Published: April 2009

A new species of Plukenetia from the Peruvian Department of Amazonas is described. Plukenetia huayllabambana R. W. Bussmann, C. Téllez & A. Glenn sp. nov. seems to be endemic to rocky patches in the cloud forest region of Mendoza. The species is similar to Plukenetia volubilis L., a species widely known from the Caribbean and Latin America, and Plukenetia stipellata L. J. Gillespie, which is only known from Central America. Both of these species occur only up to about 1200 m a.s.l., while Plukenetia huayllabambana has only been found above 1300 m a.s.l. The new species distinctly differs in its small number of stamens, stylar column length, and very large fruits and seeds. In Peru, Plukenetia spp. are widely known as ‘Sacha Inchi’ (forest Peanut), and Plukenetia huayllabambana could have a good potential to become an income source for the local communities.
Performance of Dual Fuel Engine Running on Jojoba Oil as Pilot Fuel and CNG or LPG
Authors: Selim Mohamed Y. E. , Radwan M. S. , Saleh H. E.
Published: April 2009

The use of Jojoba Methyl Ester as a pilot fuel was investigated for almost the first time as a way to improve the performance of dual fuel engine running on natural gas or LPG at part load. The dual fuel engine used was Ricardo E6 variable compression diesel engine and it used either compressed natural gas (CNG) or liquefied petroleum gas (LPG) as the main fuel and Jojoba Methyl Ester as a pilot fuel. Diesel fuel was used as a reference fuel for the dual fuel engine results. During the experimental tests, the following have been measured: engine efficiency in terms of specific fuel consumption, brake power output, combustion noise in terms of maximum pressure rise rate and maximum pressure, exhaust emissions in terms of carbon monoxide and hydrocarbons, knocking limits in terms of maximum torque at onset of knocking, and cyclic data of 100 engine cycle in terms of maximum pressure and its pressure rise rate. The tests examined the following engine parameters: gaseous fuel type, engine speed and load, pilot fuel injection timing, pilot fuel mass and compression ratio. Results showed that using the Jojoba fuel with its improved properties has improved the dual fuel engine performance, reduced the combustion noise, extended knocking limits and reduced the cyclic variability of the combustion.
Characterization of the Focal Cooling Necessary to Suppress Spontaneous Epileptiform Activity
Authors: Guerra Reynaldo G. , Carey Van , Rubinsky Boris , Berger Mitchel
Published: April 2009

It has been established that focal cooling to suppress epileptiform activity has become a real and viable option. However, the specific thermal parameters necessary to suppress epileptiform activity have only begun to be quantitatively defined. In 2002 it was reported that a 41 year-old man with medically intractable epilepsy undertook surgery to remove his tumor and resect adjacent epileptogenic tissue. Electrocorticography was performed before resection. Cold saline was impinged on the resulting interictal spike foci resulting in transient, complete cessation of spiking. We present a transient post-operative heat transfer analysis of the cold saline impingement on the surface of brain. An approximate temporal and spatial temperature distribution of the perfused human brain response to surface cooling was developed. The realistic extent of cooling below the brain surface due to impinging saline was quantified. The sensitivity of cooling penetration depth to (a) saline exit velocity from the syringe, and (b) syringe inside diameter, was evaluated. A parametric study was performed to characterize the effects of brain metabolism and blood perfusion on surface cooling. The required thermal parameters necessary to suppress epileptiform activity through focal cooling are here quantitatively approximated, i.e. heat flux removal and maximum and realistic cooling penetration depths. The relatively shallow penetration depth suggests that the spreading depolarization associated with epileptiform activity may be abolished through focal cooling without affecting the deeper neurons responsible for motor activity.
Experimental Study of Threaded and Grooved Radiating Pin Fin
Authors: Ganesh Murali J. , Subrahmanya S. Katte
Published: April 2009

An experimental study was performed to provide information on the heat radiated to the space from grooved pin fin radiator of three different geometries. Since mass is at a premium on spacecraft, the space radiator used in its temperature control system needs to be optimized with respect to mass. A literature review shows that much of work on radiating fins has been carried out analytically and numerically. Presently, a radiating pin fin with threads and grooves on its outside surface is investigated experimentally. A test facility with a vacuum chamber and instrumentation is fabricated. The heat input to the fin is varied such that the base temperature is maintained constant under steady state. Based on a study of effect of vacuum, using available resources, the chamber is designed for a vacuum of 680 mm Hg such that the contribution of convection to the total heat transfer could be ignored. The study shows that there exists optimum thread per inch (TPI), angle of threads and depth of grooves for which the heat loss per unit mass is a maximum. The threaded and grooved radiating fin loses 1.2 to 1.34 times greater heat per unit mass, respectively, compared to the bare pin fin.
Ventilation of Wind-Permeable Clothed Cylinder Subject to Periodic Swinging Motion
Authors: Ghaddar Nesreen , Ghali Kamel , Jreije Bassel
Published: April 2009

A theoretical and experimental study has been performed to determine ventilation induced by swinging motion and external wind for a fabric-covered cylinder of finite length representing a limb. The estimated ventilation rates are used in determining the sensible heat loss form a clothed cylinder using a simplified resistance model. A model is developed to estimate the external pressure distribution resulting from the relative wind around the swinging clothed cylinder. A mass balance equation of the microclimate air layer is reduced to a pressure equation assuming laminar flow in axial and angular directions and that the air layer is lumped in the radial direction. The ventilation model predicted the total renewal rate during the swinging cycle. A good agreement was found between the predicted ventilation rates at swing frequencies between 40 and 60 rpm and measured values from experiments conducted in a controlled environmental chamber (air velocity is less than 0.05 m/s) and used the tracer gas method to measure the total ventilation rate induced by the swinging motion of a cylinder covered with cotton fabric for both closed and open aperture cases. A parametric study using the current model is performed on cotton fabric to study the effect of wind on ventilation rates for a non-moving clothed limb at wind speeds ranging from 0.5–8 m/s, the effect of a swinging limb in stagnant air at frequencies up to 80 rpm, and the combined effect of wind and swinging motion on the ventilation rate. For a non-moving limb, ventilation rate increases with external wind. In absence of wind, the ventilation rate increases with increased swinging frequency. The combined effect of wind and swing is not additive of the single effects at high wind speed while at low frequency it can be assumed additive for wind speeds below 2 m/s and frequencies below 40 rpm. The heat transfer by ventilation is more than 50% of total heat loss from a clothed cylinder at f = 80 rpm in abs cense and presence of wind.
High-Pressure Combustion Phenomena
Authors: Kobayashi Hideaki
Published: April 2009

Two high-pressure combustion phenomena recently observed by the author’s group are reviewed. The first one is the flame spread of a droplet array in the supercritical pressure range of the fuel in microgravity. Microgravity experiments are essential for research on droplet combustion, especially at high pressure, because of the large Grashof number in normal gravity. The flame spread rate for an n-decane droplet array was measured at high pressure, and a fuel-vapor jet was found to be generated due to an imbalance of surface tension of the droplet surface, leading to a higher flame spread rate. The second phenomenon is turbulent premixed combustion at high pressure and high temperature, environmental conditions of which are very close to those in SI engines and premixed-type gas turbine combustors. Information on the flame characteristics in such conditions has been very limited. A high-pressure combustion test facility with a large high-pressure combustion chamber enabled us to stabilize turbulent premixed flames with a high turbulence Reynolds number and to perform flame observations and measurements for extended period using lasers. Turbulent burning velocity was successfully measured and significant effects of intrinsic flame instability on flame structure and turbulent burning velocity at high pressure were revealed. Effects of CO2 dilution on high-pressure and high-temperature premixed flames were also investigated to evaluate the fundamental effects of exhaust gas recirculation (EGR) in practical high-load high-pressure combustors.
DNS of Turbulent Channel Flow With Density Variation Under Some Conditions of Unstable Stratification
Authors: Ohta Takashi , Nakamura Kazuki , Mizobata Kazuhiko , Kajishima Takeo
Published: April 2009

We propose a new numerical method based on the usual incompressible scheme which is taking into account the density variation to realize the turbulent heat transfer prediction accurately. For the assessment of the applicability of this method for the flow field where the compressibility is not negligible even in the case of low Mach number, the direct numerical simulations (DNS) of turbulent flow in a horizontal channel of different wall temperatures are carried out by using the numerical method and the results for the turbulent flow under some conditions of unstable stratification are compared. By the 4-quadrant analysis of turbulent shear stress, it is found that the ejection events in the vicinity of the walls are particularly affected by the density variation. In addition, the global balance of the temperature profile are also affected. The results suggest that the present method is potent in simulating the change in heat transfer rate due to density fluctuation in more practical flow fields.
Numerical Simulation of Hydrogen-Air Boundary Layer Flows Augmented by Catalytic Surface Reactions
Authors: Tong Timothy W. , Abou-Ellail Mohsen M. , Li Yuan
Published: April 2009

Catalytic combustion of hydrogen-air boundary layers involves the adsorption of hydrogen and oxygen into a platinum coated surface, chemical reactions of the adsorbed species and the desorption of the resulting products. Re-adsorption of some produced gases is also possible. The catalytic reactions can be beneficial in porous burners and catalytic reactors that use low equivalence ratios. In this case the porous burner flame can be stabilized at low temperatures to prevent any substantial gas emissions, such as nitrogen oxides. The present paper is concerned with the numerical computation of heat transfer and chemical reactions in hydrogen-air mixture boundary layers that flow over platinum coated hot plates. Chemical reactions are included in the gas phase as well as on the solid platinum surface. In the gas phase, eight species are involved in 26 elementary reactions. On the platinum hot surface, additional surface species are included that are involved in 14 additional surface chemical reactions. The platinum surface temperature is fixed, while the properties of the reacting flow are computed. The flow configuration investigated in the present paper is that of a parallel boundary layer. Finite-volume equations are obtained by formal integration over control volumes surrounding each grid node. Hybrid differencing is used to ensure that the finite-difference coefficients are always positive or equal to zero to reflect the real effect of neighboring nodes on a typical central node. The finite-volume equations are solved, iteratively, for the reacting gas flow properties. On the platinum surface, surface species balance equations, under steady-state conditions, are solved numerically. A non-uniform computational grid is used, concentrating most of the nodes in the boundary sub-layer adjoining the catalytic surface. The computed OH concentration is compared with experimental and numerical data of similar geometry. The obtained agreement is fairly good, with differences observed for the location of the peak value of OH. Surface temperature of 1170 K caused fast reactions on the catalytic surface in a very small part at the leading edge of the catalytic flat plate. The computational results for heat and mass transfer and chemical surface reactions at the gas-surface interface are correlated by non-dimensional relations.
Effect of Design Variables on Voids and Thermal Performance of QFN Packages
Authors: Askari Farbod , Ladani Leila Jannesari , Dasgupta Abhijit , Rahko Matti , Sarkka Jussi
Published: April 2009

The objective of this study is to empirically investigate the dependence of solder voids and related interconnect defects in QFN packages, on such design variables as stencil aperture pattern and size, as well as quantity and location of thermal vias. A non-traditional fractional-factorial matrix was used for this study. The QFN packages produced by implementing this experiment were analyzed using destructive and nondestructive failure analysis techniques. The effect of design variables on different types of defects such as voids, and taper were evaluated. This study showed that stencil aperture size influences void area percentage the most in comparison with other design variables. An optimal stencil configuration was proposed based on void area fraction calculations. A 2-D steady-state finite element analysis was then conducted to parametrically evaluate the effect of solder voids on the performance of thermal vias under QFN thermal pads. The model confirmed that the performance of thermal vias is not very sensitive to void area fraction.
Be´nard Instability of Nanofluids
Authors: Tzou D. Y. , Pfautsch Emily J.
Published: April 2009

Be`nard instability in nanofluids is investigated in this work. With the combined effects of Brownian motion and thermophoresis of nanoparticles incorporated in natural convection, the critical Rayleigh number governing the transition from laminar to turbulent regime is shown to be 18.11, as compared to 1715.14 in regular fluids. The lower critical value, by as much as two orders of magnitude, reveals that there is heat transfer enhancement by turbulence. This effect is much more significant than the heat transfer enhancement by increased thermal conductivity alone. A nondimensional analysis is performed to extract the dominating parameters governing the turbulence enhancement. Their effects are illustrated along with the characteristic dimension of the Be`nard cells.
CFD Study of the Effect of Wall Heat Conduction on Catalytic Combustion in Split and Continuous Monolith Tubes
Authors: Grimm Michael , Mazumder Sandip
Published: April 2009

The optimum length of a monolith tube is one for which near-100% conversion is attained, and at the same time, the catalyst over the entire length of the tube is utilized. In practice, the length is adjusted by stacking monolith plugs end-to-end. In this study, the repercussions of such a practice are investigated numerically with the goal to determine if a tube of length 2L demonstrates the same behavior as two tubes of length L each, stacked end-to-end. Catalytic combustion of methane-air mixture on a platinum catalyst is considered. The studies are conducted using a multi-step reaction mechanism involving 24 surface reactions between 19 species. Two different materials are considered for the walls of the monolith tube, namely silicon carbide and cordierite. Both steady state and transient simulations are performed. Results indicate that the ignition and blowout limits can be significantly different between split and continuous tubes when the wall is made up of a high thermal conductivity material, such as silicon carbide. For steady state combustion, for both wall materials, the point of attachment of the flame to the wall is altered by splitting the tube—the effect being more pronounced for silicon carbide and at relatively high Reynolds numbers. These results imply that axial heat conduction, or lack thereof due to thermal contact resistance, affects ignition and flame stability in catalytic combustion.
Optimization of Geometry and Performance of Cooling Bundles of Parallel Tubes With Pumping Fluid Requirements
Authors: Miguel Anto´nio F. , Canhoto Paulo , Reis Anto´nio H.
Published: April 2009

This study provides answers the following question: what is the best geometry for a required level of the heat exchange, taking into account the fluid pumping power? This study shows that there exists a minimum of the fluid pumping power for the optimal heat exchanged along a stream network composed by a bundle of parallel tubes. This optimization opportunity was applied to networks under laminar and turbulent flow regime.
Experiments on the Cooling Performance of Microencapsulated Phase Change Material Suspension Flow in Rectangular Minichannels
Authors: Rao Yu , Dammel Frank , Stephan Peter
Published: April 2009

Comparative experiments were conducted in order to investigate the effects of the mass flow rate and wall heating flux on the cooling performance of water-based suspensions of microencapsulated phase change material (MEPCM) flowing through rectangular minichannels. MEPCM particles with an average size of 4.97 μm were used to form suspensions with mass concentrations ranging from 0% to 20%. The comparative experiments were performed for varying mass flow rates in the laminar region and varying thermal conditions. It was found out that the mass flow rate and wall heating flux play a significant role in the cooling performance of MEPCM suspensions. It is believed that the decreased thermal conductivity of MEPCM suspensions with the concentration and the different thermally developing flow patterns are mainly responsible for the dependence of the cooling performance of MEPCM suspensions of those parameters.
Numerical Investigation of EHD Conduction Pumping of Liquid Film With Phase-Change
Authors: Yazdani Miad , Seyed-Yagoobi Jamal
Published: April 2009

Electrohydrodynamic (EHD) conduction pumping is associated with the heterocharge layers of finite thickness in the vicinity of the electrodes, generated by the process of dissociation of the neutral electrolytic species and recombination of the generated ions. This paper numerically investigates the EHD conduction pumping of a thin liquid film in the presence of phase change. The flow system comprises a liquid film flowing over a two-dimensional flat plate while the vapor phase extended far beyond the interface to result in almost motionless vapor. The channel is separated into four different sections: the entrance, electrode, evaporation, and downstream sections. The entrance, electrode and downstream regions are adiabatic while a constant heat flux is applied in the evaporation side. The concept of EHD conduction pumping of liquid film in the presence of phase change is demonstrated in this paper. The enhanced heat transfer due to conduction pumping is evaluated.
Numerical Solution Methodology for Compact Thermal Models of Electronic Packages
Authors: Gupta Rohit Dev , Eswaran Vinayak
Published: April 2009

Compact Thermal Models (CTMs) are multi-nodal thermal resistor networks which predict the internal thermal response of an electronic package, in various environments, to within an accuracy of 2%. The junction temperature of the package is typically obtained by solving a set of linear algebraic equations wherein the heat transfer to the ambience is modeled by a convection coefficient obtained from hand-book data, assuming identical ambient conditions imposed at all nodal surfaces. In reality, this approach may give misleading results as the ambience at each of the nodal surfaces is different and depends on the cooling fluid flow behavior at that surface. In this work, a methodology is presented where the network equations of the CTMs are coupled with the governing fluid equations solved by computational fluid dynamics (CFD). The CTM+CFD approach predicts a significantly (28%) higher junction temperature as compared to the conventional CTM network solver method, even when the convection coefficient used in the latter is obtained more accurately from CFD, rather than from hand-book correlations. It is likely that the new approach offers a more effective prediction of the package thermal performance.