bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between halitosis and periodontal disease – associated oral bacteria in tongue coatings
Authors: Amou T , Hinode D , Yoshioka M , Grenier D
Published: July 2013

Aim

The objective of our study was to investigate the relationship between halitosis and oral bacteria in tongue coating (TC) and saliva samples from patients with halitosis, and to evaluate the effect of tongue cleaning on halitosis.

Methods

Ninety‐four participants complaining of oral malodour were included in the study. Organoleptic (OR) values, volatile sulphur compound (VSC) concentrations determined by gas chromatography and TC scores were used as clinical parameters of halitosis. Quantitative real‐time polymerase chain reactions were used to determine the numbers of periodontal disease–associated oral bacteria.

Results

There was a significant correlation between TC scores and OR values, methylmercaptan (CH3SH) concentrations and VSC concentrations (Spearman's rank‐correlation coefficient test, P < 0.01). There was also a positive correlation between the clinical parameters of halitosis and total bacterial numbers and Prevotella intermedia, Fusobacterium nucleatum and Campylobacter rectus concentrations in the TC samples. However, there was no similar correlation with respect to the saliva samples. The participants were sub‐divided into two groups based on whether they had the habit of tongue cleaning or not. The participants with the habit of tongue cleaning had significantly lower OR scores, VSC concentrations and P. intermedia, F. nucleatum and C. rectus levels than the other participants (Mann–Whitney U‐test, P < 0.05).

Conclusion

These results suggested that periodontal disease–associated oral bacteria in TCs are closely related to halitosis and that tongue cleaning may be an effective method for improving halitosis.
Fungal endophytes enhance wheat heat and drought tolerance in terms of grain yield and second-generation seed viability
Authors: Hubbard M. , Germida J.J. , Vujanovic V.
Published: July 2013

Aims

We evaluated the impact of fungal endophyte symbiosis on the growth, ecophysiological and reproductive success of wheat exposed to heat and drought.

Methods and Results

The resistance of pot-grown wheat to heat or drought stress was measured by quantifying efficiency of photosystem II (Fv/Fm), plant height, average seed weight (ASW), total seed weight (TSW), water-use efficiency (WUE) as well as time to 50% germination and percentage germination of second-generation seeds produced under heat stress, drought stress or well-watered conditions. The endophytic fungi tested increased wheat tolerance for drought and heat. Endophyte SMCD 2206 was the most beneficial, followed by SMCD 2210 and 2215. Surprisingly, second-generation seeds produced by drought-stressed wheat colonized by SMCD 2206, 2210 or 2215 had decreased WUE relative to those produced by endophyte-free, drought-stressed plants. However, these seeds germinated more rapidly than those produced by endophyte-free, stressed parental plants.

Conclusions

The tested consortium of endophytes has the potential to improve wheat adaptation to heat and drought.

Significance and Impact of the Study

The capacity of endophytes to increase wheat tolerance for abiotic stress and to improved germination in endophyte-free second-generation seeds arising from stressed plants could be applicable to agriculture. The mechanisms by which intergenerational endophyte-mediated affects occurs warrant further research.
Tree growth and climate in the Pacific Northwest, North America: a broad‐scale analysis of changing growth environments
Authors: Albright Whitney L. , Peterson David L.
Published: July 2013

Aim

Climate change in the 21st century will affect tree growth in the Pacific Northwest region of North America, although complex climate–growth relationships make it difficult to identify how radial growth will respond across different species distributions. We used a novel method to examine potential growth responses to climate change at a broad geographical scale with a focus on visual inspection of patterns and applications beyond sampled areas.

Location

Washington and Oregon,USA.

Methods

We examined projected changes in climate within species distributions of mountain hemlock (Tsuga mertensiana), subalpine fir (Abies lasiocarpa), Douglas‐fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa) in Washington and Oregon based on three different future climate scenarios. By drawing on knowledge from previous climate–growth studies and organizing information into climate space plots, we inferred directional changes in future radial growth.

Results

Increased moisture stress will reduce growth throughout the distribution of Douglas‐fir, but growth may increase at some energy‐limited locations. Decreased snowpack will increase growing season length and increase growth of subalpine fir and mountain hemlock at most locations, although growth may decrease at some low‐elevation sites.

Main conclusions

An altered Pacific Northwest climate will elicit different growth responses from common conifer species within their current distributions. The methodology developed in this study allowed us to qualitatively extrapolate climate–growth relationships from individual sites to entire species distributions and can identify growth responses where climate–growth data are limited.
The Relationship Between the Low‐Income Subsidy and Cost‐Related Nonadherence to Drug Therapies in Medicare Part D
Authors: Wei Iris I. , Lloyd Jennifer T. , Shrank William H.
Published: July 2013

Objectives

To examine the relationship between receiving the Medicare Part D low‐income subsidy (LIS) and cost‐related medication nonadherence (CRN).

Design

Cross‐sectional.

Setting

Medicare Consumer Assessment of Healthcare Providers and Systems (CAHPS) survey collected in spring 2007.

Participants

Part D–enrolled Medicare beneficiaries who responded to the CAHPS survey.

Measurements

Respondents were categorized into three LIS groups: deemed LIS (Medicare and Medicaid dual‐eligible and individuals receiving Supplemental Security Income), LIS applicants (other low‐income individuals who applied for and received LIS), and non‐LIS. Adjusted logistic models were used to assess the likelihood of CRN according to LIS status. Sample weights were applied in all analyses to account for complex sampling design.

Results

Of 171,573 Part D‐enrolled respondents (weighted N = 14,572,827; response rate 48%), 17.2% reported CRN. Specifically, 14.7% of non‐LIS respondents, 22.2% of deemed‐LIS respondents, and 24.0% of LIS applicants reported CRN. LIS groups had higher unadjusted odds of CRN than the non‐LIS respondents, but fully adjusted odds of CRN were lower in the deemed‐LIS (adjusted odds ratio = 0.66, 95% confidence interval = 0.59, 0.74) than the LIS applicants or the non‐LIS respondents. Subgroup analyses revealed that sociodemographic and health‐related characteristics were associated with higher CRN in all three groups.

Conclusion

The lower adjusted odds of CRN in deemed‐LIS is reassuring, suggesting that autoenrollment provides meaningful assistance in removing cost‐related barriers to medication use, but certain sociodemographic characteristics were associated with higher odds of CRN. Efforts to improving outreach to these subgroups and tracking of CRN are warranted.
Sources of Variation on the Mini‐Mental State Examination in a Population‐Based Sample of Centenarians
Authors: Dai Ting , Davey Adam , Woodard John L. , Miller Lloyd Stephen , Gondo Yasuyuki , Kim Seock‐Ho , Poon Leonard W.
Published: July 2013

Centenarians represent a rare but rapidly growing segment of the oldest‐old. This study presents item‐level data from the Mini‐Mental State Examination (MMSE) in a cross‐sectional, population‐based sample of 244 centenarians and near‐centenarians (aged 98–108, 16% men, 21% African‐American, 38% community dwelling) from the Georgia Centenarian Study (2001–2008) according to age, education, sex, race, and residential status. Multiple‐Indicator Multiple‐Cause (MIMIC) models were used to identify systematic domain‐level differences in MMSE scores according to demographic characteristics in this age group. Indirect effects of age, educational attainment, race, and residential status were found on MMSE scores. Direct effects were limited to concentration for education and race and orientation for residential status. Mean levels of cognitive functioning in centenarians were low, with mean values below most commonly‐used cutoffs. Overall scores on the MMSE differed as a function of age, education, race, and residential status, with differences in scale performance limited primarily to concentration and orientation and no evidence of interactions between centenarian characteristics. Adjusting for education was not sufficient to account for differences according to race, and adjusting for residential status was not sufficient to account for differences according to age.
Why Do Older Unhealthy Drinkers Decide to Make Changes or Not in Their Alcohol Consumption? Data from the Healthy Living as You Age Study
Authors: Borok Jenna , Galier Peter , Dinolfo Matteo , Welgreen Sandra , Hoffing Marc , Davis James W. , Ramirez Karina D. , Liao Diana H. , Tang Lingqi , Karno Mitch , Sacco Paul , Lin James C. , Moore Alison A.
Published: July 2013

Objectives

To understand characteristics of older at‐risk drinkers and reasons why they decide to change or maintain their alcohol consumption.

Design

Secondary analysis of data from a randomized controlled trial to reduce drinking in at‐risk drinkers.

Setting

Three primary care sites in southern California.

Participants

Six hundred thirty‐one adults aged 55 and older who were at‐risk drinkers at baseline, 521 of whom who completed a 12‐month assessment.

Measurements

Sociodemographic and alcohol‐related characteristics of 12‐month assessment completers and noncompleters and among those completing the 12‐month assessment by telephone or mail were compared using descriptive statistics. Reasons why respondents maintained or changed average alcohol consumption were asked of those who completed a 12‐month assessment by telephone. Factors that might motivate at‐risk drinkers to reduce drinking were asked about, and frequencies were calculated for these responses.

Results

Participants were primarily male, white, highly educated, and in good health. Those who responded to the 12‐month assessment by mail were more likely to be working, to be in the intervention arm, and to drink more. Most who reduced alcohol consumption and heavy drinking did so because they thought it would benefit them. Those who did not thought that drinking was not a problem for them. Both groups cited their environment and circumstances as influencing their drinking. Remaining at‐risk drinkers reported that medical evidence that alcohol was harming them would motivate them to reduce drinking.

Conclusion

Older adults report that they reduce their drinking when they recognize that their drinking habits may be causing them harm; one's environment can hinder or help one to reduce drinking.
What Students Experienced: A Narrative Analysis of Essays Written by First‐Year Medical Students Participating in a Geriatrics Home Visit
Authors: O'Donnell Linsey , Carson Lesley , Forciea Mary Ann , Kinosian Bruce , Shea Judy , Yudin Jean , Miller Rachel K.
Published: July 2013

Objectives

To develop a house call experience for first‐year medical students introducing them to challenges that homebound, chronically ill elderly adults face.

Design

During the semester, two students were paired with a preceptor to see two to three patients.

Setting

The house call practices of the Division of Geriatric Medicine at the University of Pennsylvania and the Philadelphia Veterans Affairs Hospital.

Participants

One hundred sixty‐five first‐year medical students.

Measurements

Pairs of students worked together to write an essay after the visit. Essays addressed specific areas, as detailed in a provided checklist, including noting patients' functional limitations, identifying community supports available to patients, and writing about general surprises that the students discovered during their visit. These data were then measured using narrative analysis.

Results

In all domains, students identified core goals and objectives. In the first domain (meeting challenges of functional limitations), students recognized the importance of family support. In the second domain (mentioning of functional limitation), high levels of compliance were seen. In the third domain (community support), students mentioned specific formal supports. In the fourth domain (surprises during the visit), students identified many important geriatrics concepts.

Conclusion

In writing their essays, students demonstrated a high level of recognition of functional impairment and noted the importance of family, social networks, and home environment in enabling homebound, chronically ill elderly adults to stay in their homes. Many students also demonstrated an awareness of the possibilities of independence and happiness despite significant illness and disability.
How dointensive carenurses perceive families in intensive care? Insights from the United Kingdom and Australia
Authors: Kean Susanne , Mitchell Marion
Published: July 2013

Aims and objectives

To compare how intensive care nurses in theUKand Australia (AU) perceive families in intensive care units (ICUs).

Background

International healthcare research and practice is often based on an underlying assumption of a person‐ or family‐centred ideology. While nurses in ICUs acknowledge the importance of patients' families, a true integration of families as units of care is often not realised.

Design

Data fromICUnurses from two international studies: (1) a constructivist grounded theory study in theUKand (2) a quasi‐experimental non‐equivalent clinical study inAU. Data were collected in tertiary adultICUs in theUKandAU. Nurse‐to‐patient ratio for high‐acuity patients was 1:1 in both units.

Participants

TwentyICUnurses in five focus groups (UKstudy) and 197 surveys were sent out toICUnurses inAU(response rate 26%).

Results

Evidence from both studies makes visible the contribution of family care in adultICUs. Nurses remaining in control and initiating family member care involvement are less likely to perceive families as a burden. TheAUstudy indicated that when nurses partner with families to deliver care, there was a minimal effect on their workload. The nurses concluded that inviting family members to be a part of the patient's care should be usual practice inICUs.

Conclusion

Nurses should promote, facilitate and invite the integration of families in care in today's healthcare system. This is mandatory as families are the caring resource for these patients during an often prolonged recovery trajectory.

Relevance to clinical practice

Families are more likely to be successfully integrated into a more active involvement withICUpatients when they are not perceived as a burden. Inviting and supporting family members is not necessarily time‐consuming and starts the journey of supportingICUsurvivors' recovery journey.
Time‐Varying Fund Manager Skill
Authors: KACPERCZYK MARCIN , NIEUWERBURGH STIJN VAN , VELDKAMP LAURA
Published: July 2013

We propose a new definition of skill as general cognitive ability to pick stocks or time the market. We find evidence for stock picking in booms and market timing in recessions. Moreover, the same fund managers that pick stocks well in expansions also time the market well in recessions. These fund managers significantly outperform other funds and passive benchmarks. Our results suggest a new measure of managerial ability that weighs a fund's market timing more in recessions and stock picking more in booms. The measure displays more persistence than either market timing or stock picking alone and predicts fund performance.
Effect of Clasp Design on Retention at Different Intervals Using Different Abutment Materials and in a Simulated Oral Condition
Authors: Helal Mohamed A. , Baraka Osama A. , Sanad Mohamed E. , Al‐Khiary Yasser , Ludwig Klaus , Kern Matthias
Published: July 2013

Purpose

The purpose of this study was to compare the retention of circlet (E) clasps and back‐action clasps against three abutment surface materials during long‐term simulation of attachment and detachment.

Material and Methods

Forty‐eight test models were constructed by placing premolars (natural abutments or metal dies) inside metal blocks to test different abutment retention surface materials (sound enamel, composite resin, and glass‐ceramic; 16 each). The models were duplicated into investment models for construction of circlet (E) and back‐action clasps. Removal and insertion cycling of clasps was carried out for 250, 500, 1000, 2000, 4000, 8000, and 16,000 cycles. The retention of each clasp was measured before cycling and after each interval. Data were analyzed using 1‐way‐ANOVA, 2‐way‐ANOVA, and Mann‐Whitney U tests.

Results

No significant differences in retention of either clasp were found between the three abutment material surfaces; however, there was a significant decrease in retention force of the circlet (E) clasp between 1000 and 2000 cycles but not of the back‐action clasp.

Conclusions

(1) The back‐action clasp maintains its retention force for a longer period than the circlet (E) clasp. (2) Composite resin contouring of teeth provided retention comparable to enamel and a ceramic material.
Chinese L2 Literacy Development: Cognitive Characteristics, Learning Strategies, and Pedagogical Interventions
Authors: Shen Helen H.
Published: July 2013

The field of Chinese L2 education has expanded rapidly in the past two decades. It has become a central research agenda for Chinese L2 scholars to seek answers to the question of how western learners learn to read logographic writing that is drastically different from their native languages in orthography. This paper approaches this question by focusing on the core issue of literacy development: character learning. The discussion covers the aspects of the cognitive characteristics of learners' development of their metalinguistic awareness in Chinese, the strategies they employed in the process of learning to read and write Chinese characters, and the optimum pedagogical practices to facilitate character learning.
Perioperative temperature elevation: not all hyperthermia is malignant hyperthermia
Authors: Herlich Andrew
Published: July 2013

Objectives

The objective of this review is to assist the readers, anesthesiologists, intensivists, and emergency physicians in making a more accurate diagnosis of perioperative fever or hyperthermia and subsequently choose the proper course of treatment.

Aim

To identify the many sources of perioperative fever and after a more accurate differential diagnosis, select appropriate treatment options. Most anesthesiologists, intensivists, and emergency physicians are not familiar with an expansive differential of perioperative fever. This article attempts to expose these physicians to that differential diagnosis.

Background

Much of the medical literature has anecdotal reports, small case series, or limited reviews of the possible sources of hyperthermia or fever. This is especially true of the anesthesia literature.

Results

A literature search was performed which identified many possible common and uncommon sources of fever. Some of these sources are quite relevant to the anesthesiologist. Other sources had potential relevance in obscure cases.
Physiological, biochemical and molecular responses of the potato (Solanum tuberosum L.) plant to moderately elevated temperature
Authors: HANCOCK ROBERT D. , MORRIS WAYNE L. , DUCREUX LAURENCE J. M. , MORRIS JENNY A. , USMAN MUHAMMAD , VERRALL SUSAN R. , FULLER JOHN , SIMPSON CRAIG G. , ZHANG RUNXUAN , HEDLEY PETE E. , TAYLOR MARK A.
Published: July 2013

As we demonstrate in this study, potato tuber yield is susceptible to mild temperature stress. We demonstrate that despite the decreased tuber yield, there is an increase in net foliar photosynthesis at mildly elevated temperature. Using metabolomic and transcriptomic approaches we demonstrate profound effects in both metabolite profiles and transcript patterns in tubers in leaves, at the elevated temperature. RT‐PCR revealed perturbation in the expression of circadian clock transcripts including StSP6A, previously identified as a tuberisation signal. Our data indicate that potato plants grown at moderately elevated temperatures do not exhibit classic symptoms of abiotic stress but that tuber development responds via a diversity of biochemical and molecular signals.
On a Coupled Nonlinear Schrödinger System: A Ermakov Connection
Authors: Rogers Colin
Published: July 2013

[Dedicated to the memory of Sergei Manakov]

Ermakov‐type invariants are isolated for a subsystem of an N‐component coupled nonlinear Schrödinger system. An algorithmic procedure is presented which reduces this Ermakov–Ray–Reid system to quadrature. The method is illustrated in the single component case by application to a nonlinear system descriptive of the propagation of transverse waves in incompressible hyperelastic media subject to rotation. An extended Ermakov–Ray–Reid system is presented which, if it has underlying Hamiltonian structure, is also amenable to the algorithm.
Experimental Study of Strengthening an RC Bridge Deck by Adding a Concrete Overlay
Authors: Theiner Y. , Hart H. , Drexel M. , Hofstetter G.
Published: July 2013

The present contribution focuses on the experimental investigation of moisture distribution profiles of a reinforced concrete bridge deck determined before, during and after adding a concrete overlay. By means of a non‐destructive system, the mass water content distributions were measured in the existing bridge deck as well as in the concrete overlay. Furthermore, the in situ measurements were accompanied by a comprehensive laboratory test programme. Water desorption isotherms and ultimate drying shrinkage strain were determined on specimens made of both the substrate and overlay concrete. Moreover, moisture distributions and shrinkage strains were measured on concrete prisms stored under uniform climatic conditions. Comparison of in situ measurements with lab test results allows a better understanding of the impact of environmental influences on the bonded overlay behaviour. Comparison of in situ measurements with previous lab test results allows the assessment of the effectivity of surface preparation by high‐pressure water jetting and, hence, the examination of the significance of results from composite lab tests for real bridge decks strengthened by overlays. A comparison of an experimental and numerical study of restraint effects exerted from the substrate concrete on the overlay will be presented in an accompanying paper.
Undertaking recreational trespass: urban exploration and infiltration
Authors: Garrett Bradley L
Published: July 2013

Urban exploration is a practice of researching, rediscovering and physically exploring temporary, obsolete, abandoned, derelict and infrastructural areas within built environments without permission to do so. Drawing from four years of ethnographic research with a group of urban explorers in the United Kingdom who undertook increasingly brazen forays into off‐limits architecture, this paper argues that while urban exploration can be connected to earlier forms of critical spatial engagement, the movement also speaks to the current political moment in unique ways. Urban explorers are one of many groups reacting to increased surveillance and control over urban space, playfully probing boundaries and weaknesses in urban security in a search for bizarre, beautiful and unregulated areas where they can build personal relationships to places. The results of this research both complement and complicate recent work within geography around issues of surveillance, subversion, urban community building and critical engagement with cities.
Community participatory appraisal in migration research: connecting neoliberalism, rural restructuring and mobility
Authors: Torres Rebecca Maria , Carte Lindsey
Published: July 2013

This article argues for a ‘participatory turn’ in migration research – one that incorporates participatory methods as a complementary or principal means for examining transnational migration. We make the case for using participatory appraisal (PA) in migration studies by presenting illustrative examples of how this approach enriched research we conducted in Veracruz, Mexico, on neoliberalism, agrarian transformation and migration. We facilitated workshops with 23 adults, 57 elementary school children and 45 secondary school youths employing a range of participatory ‘tools’ that are highly visual and interactive, including, community histories, diagramming, matrix rankings and ‘photovoice’. We provide concrete examples from this experience to illustrate the potential power of PA in migration research to elucidate the connections between neoliberal rural restructuring and migration, to facilitate fruitful contrast of community typologies and to include underrepresented and marginalised voices such as those of children and youths who are often silent in migration research. Through the workshops we gained grounded, multi‐scalar and diverse understandings of ‘actually existing neoliberalism’ as participants untangled the complex relationships between neoliberal practice, rural and agrarian restructuring, and migration. This allows richer and more nuanced understandings and theorisation of diverse factors shaping migration and its effects across multiple scales, while also empowering local people as co‐producers of knowledge with the possibility of envisaging alternative futures.
Negative governance: vulnerability, biopolitics and the origins of government
Authors: Rose Mitch
Published: July 2013

This paper develops the concept of negative governance, an idea that describes (1) a unique and specific modality of governance and (2) a way to think about the concept of governance in general. In terms of the former, negative governance describes a way of governing that works by refusing to govern. This refusal is not simply a denial of state provision (since this assumes a governing agent), but a denial of state management. Negative governance is a system of governing paradoxically predicated on the withdrawal of all positive procedures of state and a delegation of power to those forces that are by definition outside the state's capacities. It governs by allowing ‘life itself’ – life in all is chaotic unpredictability – to rule. In terms of the latter, negative governance raises questions about the origins of governance. Specifically, it asks ‘what is it that calls for governance?’ My answer is that the ‘call to govern’ emanates from a place wholly outside the state and the state's own representational logic. Expanding upon Levinas’ concept of the elemental, I argue that the state is not the agent that makes subjects vulnerable. On the contrary, vulnerability is a human condition: the body demands food, our loved ones come and go, death is always present. It is this basic vulnerability that calls for governance. And government is a response to this negative condition.
Impact of the Combustor-Turbine Interface Slot Orientation on the Durability of a Nozzle Guide Vane Endwall
Authors: Thrift Alan , Thole Karen , Hada Satoshi
Published: July 2013

The combustor-turbine interface is an essential component in a gas turbine engine as it allows for thermal expansion between the first stage turbine vanes and combustor section. Although not considered as part of the external cooling scheme, leakage flow from the combustor-turbine interface can be utilized as coolant. This paper reports on the effects of orientation of a two-dimensional leakage slot, simulating the combustor-turbine interface, on the net heat flux reduction to a nozzle guide vane endwall. In addition to adiabatic effectiveness and heat transfer measurements, time-resolved, digital particle image velocimetry (TRDPIV) measurements were performed in the vane stagnation plane. Four interface slot orientations of 90 deg, 65 deg, 45 deg, and 30 deg located at 17% axial chord upstream of a first vane in a linear cascade were studied. Results indicate that reducing the slot angle to 45 deg can provide as much as a 137% reduction to the average heat load experienced by the endwall. Velocity measurements indicate the formation of a large leading edge vortex for coolant injected at 90 deg and 65 deg while coolant injected at 45 deg and 30 deg flows along the endwall and washes up the vane surface at the endwall junction.
High Resolution Heat Transfer Measurement on Flat and Contoured Endwalls in a Linear Cascade
Authors: Laveau Benoit , Abhari Reza S. , Crawford Michael E. , Lutum Ewald
Published: July 2013

In order to continue increasing the efficiency of gas turbines, a significant effort is being made to reduce losses induced by secondary flows in turbine stages. In addition to their impact on aerodynamic losses, these vortical structures are also the source of large heat transfer variations across the passage. A substantial reduction of the secondary flow losses can be achieved with a contoured endwall. However, a change in the vortical pattern can dramatically impact the thermal loads on the endwalls and lead to higher cooling requirements in those areas. This paper focuses on heat transfer measurements made in a passage with either flat or contoured endwalls. The experimental data are supplemented with numerical predictions of the heat transfer data. The measurements are carried out on an isothermal endwall equipped with symmetric airfoils. The paper presents measurements at M = 0.3, corresponding to a Reynolds number ReCax=4.6×105. An infrared camera is used to provide high-resolution surface temperature data on the endwall. The surface is equipped with an insulating layer (Kapton), allowing the calculation of heat flux through the endwall. The heat transfer quantities, namely the heat transfer coefficient and the adiabatic wall temperature, are then derived from a set of measurements at different isothermal plate temperatures. The numerical predictions clarify the link between the change in the heat transfer quantities and the changes in the flow field due to endwall contouring. Finally, numerically predicted heat transfer data are deduced from a set of adiabatic and diabatic simulations that are compared to the experimental data. The comparison focuses on the differences in the regions with endwall contouring, where a significant difference in the heat transfer coefficient between flat and contoured endwalls is measured but underpredicted numerically.
Postgrowth Microwave Treatment to Align Carbon Nanotubes
Authors: Nguyen J. J. , Bougher T. L. , Pour Shahid Saeed Abadi P. , Sharma A. , Graham S. , Cola B. A.
Published: July 2013

We show that a commercial microwave oven can be used after growth to increase alignment of carbon nanotubes (CNTs) and reduce their resistance as thermal and electrical interface materials. Forests of multiwall CNTs were grown directly on both sides of aluminum foils by thermal chemical vapor deposition (CVD) and subsequently exposed to a microwave treatment in air. Scanning electron micrographs revealed enhanced vertical alignment of CNTs after postgrowth microwave treatment. The microwave treatment creates an electric field near the CNT growth substrate that aligns the CNTs orthogonally to the growth substrate. Microwaved CNT forests produced increased mechanical stiffness by approximately 58%, and reduced thermal and electrical contact resistances by 44% and 41%, respectively, compared to as-grown forests. These performance changes are attributed to an increase in the real contact area established at the CNT distal ends because of the enhanced forest alignment. This conclusion is consistent with several prior observations in the literature. This work demonstrates a facile method to enhance the alignment of CNTs grown by thermal CVD without the use of in situ plasma or electric field application.
Convective Heat Transfer and Pressure Loss in Rectangular Ducts With Inclined Pin-Fin on a Wavy Endwall
Authors: Takeishi Kenichiro , Oda Yutaka , Miyake Yoshiaki , Motoda Yusuke
Published: July 2013

Local endwall heat transfer characteristics and overall pressure loss of normal and inclined pin fins arrayed in rectangular ducts with flat and wavy endwalls have been investigated to improve the cooling efficiency of jet engine combustor liners. The detailed time-mean local Nusselt number profiles were measured using a naphthalene sublimation method based on the heat/mass transfer analogy. Four kinds of angled pin fins (−45, 0, and +45 deg with a flat endwall, and −45 deg with a wavy endwall) were tested and compared with each other. As a result, the average heat transfer coefficient on the flat endwall of normal pin fins was higher than that of the angled pin fins. The average heat transfer coefficient of −45-deg inclined pin fins with a wavy endwall is the same or a little higher than the heat transfer coefficient of those with a flat endwall; however, the pressure loss of the −45-deg inclined pin fins with a wavy endwall is less than the pressure loss of those with a flat endwall. Corresponding numerical simulations using large eddy simulation (LES) with the mixed time scale (MTS) model have been also conducted at Red = 1000 for fully developed regions, and the results have shown good quantitative agreement with mass transfer experiments. It can be concluded that wavy endwalls can realize better heat transfer with less pressure loss as long as the aim consists in enhancing endwall heat transfer in inclined pin-fin channels.
Modeling and Optimization of Unburned Carbon in Coal-Fired Boiler Using Artificial Neural Network and Genetic Algorithm
Authors: Ilamathi P. , Selladurai V. , Balamurugan K.
Published: July 2013

An approach to model coal combustion process to predict and minimize unburned carbon in bottom ash of a large-capacity pulverized coal-fired boiler used in thermal power plant is proposed. The unburned carbon characteristic is investigated by parametric field experiments. The effects of excess air, coal properties, boiler load, air distribution scheme, and nozzle tilt are studied. An artificial neural network (ANN) is used to model the unburned carbon in bottom ash. A genetic algorithm (GA) is employed to perform a search to determine the optimum level process parameters in ANN model which decreases the unburned carbon in bottom ash.
DrillString Vibration With Hole-Enlarging Tools: Analysis and Avoidance
Authors: Samuel Robello , Yao Dongping
Published: July 2013

In high-risk, high-cost environments, such as ultra-deep waters, refining advanced technologies for the successful completion of wells is paramount. Challenges are still very much associated with complex bottomhole assemblies (BHAs) and with the vibration of the drillstring when used with hole enlarging tools. These tools with complex profiles and designs become additional excitation sources of vibration. The more widespread use of downhole tools for both directional telemetry and logging-while-drilling (LWD) applications, as part of the front line data acquisition system within the drilling process, has made reliability a prime area of importance. This paper presents and validates an existing model to predict severe damaging vibrations. It also provides analysis techniques and guidelines to successfully avoid the vibration damage to downhole tools and to their associated downhole assemblies when using hole enlarging tools, such as hole openers and underreamers. The dynamic analysis model is based on forced frequency response (FFR) to solve for resonant frequencies. In addition, a mathematical formulation includes viscous, axial, torsional, and structural damping mechanisms. With careful consideration of input parameters and the judicious analysis of results, we demonstrated that drillstring vibration can be avoided by determining the three-dimensional vibrational response at selected excitations that are likely to cause them. In addition, the analysis provides an estimate of relative bending stresses, shear forces, and lateral displacements for the assembly used. Based on the study, severe vibrations causing potentially damaging operating conditions that had been a major problem in nearby wells were avoided. Steps required to estimate the operating range of the drilling parameter such as weight on bit and rotational speeds to mitigate and avoid the downhole tool failures due to vibration are given. Extensive simulations were performed to compare the data from the downhole vibration sensors; this paper includes severe vibration incidence data from three case studies in which the model estimated, predicted, and avoided severe vibration (Samuel, R., et al., 2006, “Vibration Analysis Model Prediction and Avoidance: A Case History,” Paper SPE 102134 Presented at the IADC India Conference, Mumbai, India, Oct. 16–18; Samuel, R., 2010, “Vibration Analysis for Hole Enlarging Tools” SPE 134512, Annual Technical Conference, Florence, Italy).
Ultrasonic Measurement of Multiphase Flow Erosion Patterns in a Standard Elbow
Authors: Kesana N. R. , Grubb S. A. , McLaury B. S. , Shirazi S. A.
Published: July 2013

Solid particle erosion is a mechanical process in which material is removed from a surface due to impacts of solid particles transported within a fluid. It is a common problem faced by the petroleum industry, as solid particles are also produced along with oil and gas. The erosion not only causes economic losses resulting from repairs and decreased production but also causes safety and environmental concerns. Therefore, the metal losses occurring in different multiphase flow regimes need to be studied and understood in order to develop protective guidelines for oil and gas production equipment. In the current study, a novel noninvasive ultrasonic (UT) device has been developed and implemented to measure the metal loss at 16 different locations inside an elbow. Initially, experiments were performed with a single-phase carrier fluid (gas-sand) moving in the pipeline, and the erosion magnitudes are compared with computational fluid dynamics (CFD) results and found to be in good agreement. Next, experiments were extended to the multiphase slug flow regime. Influence of particle diameter and liquid viscosity were also studied. Two different particle sizes (150 and 300 μm sand) were used for performing tests. The shapes of the sand are also different with the 300 μm sand being sharper than the 150 μm sand. Three different liquid viscosities were used for the present study (1 cP, 10 cP, and 40 cP). While performing the UT experiments, simultaneous metal loss measurements were also made using an intrusive electrical resistance (ER) probe in a section of straight pipe. The probe in the straight pipe is an angle-head probe which protrudes into the flow with the face placed in the center of the pipe. The UT erosion measurements in a bend are also compared with experimental data obtained placing an intrusive flat head ER probe flush in a bend, and the results were found to be in good agreement. Finally, the noninvasive nano UT permanent placement temperature compensated ultrasonic wall thickness device developed for this work has the capability of measuring metal loss at many locations and also identifying the maximum erosive location on the pipe bend.
Framework for a Combined Netting Analysis and Tsai-Wu-Based Design Approach for Braided and Filament-Wound Composites
Authors: Hossain Rifat , Carey Jason P. , Mertiny Pierre
Published: July 2013

Axially symmetric fiber-reinforced polymer composite structures, such as pressure vessels and piping, are being widely used in different industrial applications where combined loading conditions may be applied. It is imperative to determine a suitable fiber angle, or a distribution of fiber angles, along the longitudinal direction of the structure in order to achieve best performance in terms of mechanical behavior and strength for structures subjected to combined loadings. To this end, an approach combining netting analysis and Tsai-Wu failure theory was employed as a design tool to assess critical fiber angles at which applied loadings would cause a structure to fail. Together, the proposed netting analysis and failure theory-based approach constitute a simple, expedient, and convenient design process for complex-shaped structures.
High Temperature Thermal Energy Storage Utilizing Metallic Phase Change Materials and Metallic Heat Transfer Fluids
Authors: Kotzé Johannes P. , von Backström Theodor W. , Erens Paul J.
Published: July 2013

Cost and volume savings are some of the advantages offered by the use of latent heat thermal energy storage (TES). Metallic phase change materials (PCMs) have high thermal conductivity, which relate to high charging and discharging rates in TES system, and can operate at temperatures exceeding 560 °C. In the study, a eutectic aluminium–silicon alloy, AlSi12, is identified as a good potential PCM. AlSi12 has a melting temperature of 577 °C, which is above the working temperature of regular heat transfer fluids (HTFs). The eutectic sodium–potassium alloy (NaK) is identified as an ideal HTF in a storage system that uses metallic PCMs. A concept is presented that integrates the TES-unit and steam generator into one unit. As NaK is highly reactive with water, the inherently high thermal conductivity of AlSi12 is utilized in order to create a safe concept. As a proof of concept, a steam power-generating cycle was considered that is especially suited for a TES using AlSi12 as PCM. The plant was designed to deliver 100 MW with 15 h of storage. Thermodynamic and heat transfer analysis showed that the concept is viable. The analysis indicated that the cost of the AlSi12 storage material is 14.7 US$per kWh of thermal energy storage.
Direct Sinter Bonding of Metal Injection-Molded Parts to Solid Substrate Through Use of Deformable Surface Microfeatures
Authors: Martens Thomas , Mears M. Laine
Published: July 2013

In the metal injection molding (MIM) process, fine metal powders are mixed with a binder and injected into molds, similar to plastic injection molding. After molding, the binder is removed from the part, and the compact is sintered to almost full density. Though able to create high-density parts of excellent dimensional control and surface finish, the MIM process is restricted in the size of part that can be produced, due to gravitational deformation during high-temperature sintering and maximum thickness requirements to remove the binding agents in the green state. Larger parts could be made by bonding the green parts to a substrate during sintering; however, a primary obstacle to this approach lies in the sinter shrinkage of the MIM part, which can be up to 20%, meaning that the MIM part shrinks during sintering, while the conventional substrate maintains its dimensions. This behavior would typically inhibit bonding and/or cause cracking and deformation of the MIM part. In this work, we present a structure of micro features molded onto the surface of the MIM part, which bonds, deforms, and allows for shrinkage while bonding to the substrate. The micro features tolerate plastic deformation to permit the shrinkage without causing cracks after the initial bonds are established. In a first series of tests, bond strengths of up to 80% of that of resistance welds have been achieved. This paper describes how the authors developed their proposed method of sinter bonding and how they accomplished effective sinter bonds between MIM parts and solid substrates.
Effects of Fuel Temperature on Injection Process and Combustion of Dimethyl Ether Engine
Authors: Guangxin Gao , Zhulin Yuan , Apeng Zhou , Shenghua Liu , Yanju Wei
Published: July 2013

To investigate the effects of fuel temperature on the injection process in the fuel-injection pipe and the combustion characteristics of compression ignition (CI) engine, tests on a four stroke, direct injection dimethyl ether (DME) engine were conducted. Experimental results show that as the fuel temperature increases from 20 to 40 °C, the sound speed is decreased by 12.2%, the peak line pressure at pump and nozzle sides are decreased by 7.2% and 5.6%, respectively. Meanwhile, the injection timing is retarded by 2.2 °CA and the injection duration is extended by 0.8 °CA. Accordingly, the ignition delay and the combustion duration are extended by 0.7 °CA and 4.0 °CA, respectively. The cylinder peak pressure is decreased by 5.4%. As a result, the effective thermal efficiency is decreased, especially for temperature above 40 °C. Before beginning an experiment, the fuel properties of DME, including the density, the bulk modulus, and the sound speed were calculated by “ThermoData.” The calculated result of sound speed is consistent with the experimental results.
Prospects for Biofuels: A Review
Authors: Oehlschlaeger Matthew A. , Wang Haowei , Sexton Mitra N.
Published: July 2013

Biofuels have the potential to be sustainable, secure, low carbon footprint transportation fuels. Primarily due to government mandates, biofuels have become increasingly adopted as transportation fuels over the last decade and are projected to steadily increase in production. Here the prospects of biofuels are summarized in terms of several important performance measures, including: lifecycle greenhouse gas (GHG) emissions, energy return on investment (EROI), land and water requirements, and tailpipe emissions. A review of the literature leads to the conclusion that most first-generation biofuels, including corn ethanol and soybean biodiesel produced in the United States, reduce tailpipe pollutant emissions and GHG emissions—provided their feedstocks do not replace large quantities of fixed carbon. However, their production is perhaps unsustainable due to low EROI and significant land-use and water requirements. Second-generation biofuels; for example ethanol produced from lignocellulosic biomass, have the potential for larger reductions in GHG emissions and can provide sustainable EROI with reasonable land area usage; however, they require water inputs several orders-of-magnitude greater than required by petroleum fuels. Advanced biofuels from algal oils and synthetic biological processes are further from commercial reality and require more assessment but potentially offer better performance due to their orders-of-magnitude greater yields per land area and lower water requirements; at present, the energy costs of such biofuels are uncertain.
Manufacturing Experience in an Advanced 9%CrMoCoVNbNB Alloy for Ultra-Supercritical Steam Turbine Rotor Forgings and Castings
Authors: Vanstone Rod , Chilton Ian , Jaworski Pawel
Published: July 2013

Advanced 9–12%Cr martensitic stainless steels to enable extension of steam turbine operating temperatures beyond 565 °C have been under development since the 1980s. Steam turbines with operating temperatures approaching 600 °C based on the first generation of these improved alloys, which exploited optimized levels of Mo, W, V, Nb, and N, entered service in the 1990s. Around the same time, a second generation of advanced alloys was developed incorporating additions of Co and B to further enhance creep strength. These alloys have recently been exploited to enable steam turbines with operating temperatures of up to 620 °C, and this new generation of steam turbines is now beginning to enter service. This paper describes the background to the development of these alloys and the experience gained in their application to the manufacture of high temperature rotor forgings and castings.