bluuebunny/crossref_metadata_2025 huggingface dataset:
Diversity in primary palate ontogeny of amniotes revealed with 3D imaging
Authors: Abramyan John , Thivichon‐Prince Beatrice , Richman Joy Marion
Published: April 2015

The amniote primary palate encompasses the upper lip and the nasal cavities. During embryonic development, the primary palate forms from the fusion of the maxillary, medial nasal and lateral nasal prominences. In mammals, as the primary palate fuses, the nasal and oral cavities become completely separated. Subsequently, the tissue demarcating the future internal nares (choanae) thins and becomes the bucconasal membrane, which eventually ruptures and allows for the essential connection of the oral and nasal cavities to form. In reptiles (including birds), the other major amniote group, primary palate ontogeny is poorly studied with respect to prominence fusion, especially the formation of a bucconasal membrane. Using 3D optical projection tomography, we found that the prominences that initiate primary palate formation are similar between mammals and crocodilians but distinct from turtles and lizards, which are in turn similar to each other. Chickens are distinct from all non‐avian lineages and instead resemble human embryos in this aspect. The majority of reptiles maintain a communication between the oral and nasal cavities via the choanae during primary palate formation. However, crocodiles appear to have a transient separation between the oral and nasal cavities. Furthermore, the three lizard species examined here, exhibit temporary closure of their external nares via fusion of the lateral nasal prominences with the frontonasal mass, subsequently reopening them just before hatching. The mechanism of the persistent choanal opening was examined in chicken embryos. The mesenchyme posterior/dorsal to the choana had a significant decline in proliferation index, whereas the mesenchyme of the facial processes remained high. This differential proliferation allows the choana to form a channel between the oral and nasal cavities as the facial prominences grow and fuse around it. Our data show that primary palate ontogeny has been modified extensively to support the array of morphological diversity that has evolved among amniotes.
The impact of a hospital‐based educational video on maternal perceptions and planned practices of infant safe sleep
Authors: Canter Jennifer , Rao Vinod , Patrick Patricia A. , Alpan Gad , Altman Robin L.
Published: April 2015

Purpose

To evaluate whether an educational video would impact infant sleep practices among new mothers.

Design and Methods

Survey responses of new mothers who did (n = 43) versus did not (n = 49) watch the educational video were compared to identify differences in observed and planned infant sleep practices.

Results

Mothers who watched the video were more likely to observe safe sleep practices while in the hospital (67.4% vs. 46.9%, p < .05). They were also less likely to plan for (unsafe) side positioning (23.9% vs. 7.1%, p < .05).

Practice Implications

Given the potentially fatal consequence of unsafe sleep, a brief video provided by nursing staff can be a prudent component of new parent education.
A meta‐analytic assessment of the risk of chronic kidney disease in patients with chronic hepatitis C virus infection
Authors: Park H. , Adeyemi A. , Henry L. , Stepanova M. , Younossi Z.
Published: April 2015

Epidemiological studies have reported conflicting results regarding hepatitis C virus (HCV) infection and the risk of chronic kidney disease (CKD). We systematically reviewed the literature to determine the risk of developing CKD in HCV‐infected individuals compared to uninfected individuals. MEDLINE and PUBMED were searched to identify observational studies that had reported an association between HCV and CKD or end‐stage renal disease (ESRD) through January 2015. Quantitative estimates [hazard ratio (HR) or odds ratio (OR)] and their 95% confidence intervals (CI) were extracted from each study. A random‐effects meta‐analysis was performed. Fourteen studies evaluating the risk of developing CKD/ESRD in HCV‐infected individuals (n = 336 227) compared to uninfected controls (n = 2 665 631) were identified‐ nine cohort studies and five cross‐sectional studies. The summary estimate indicated that individuals with HCV had a 23% greater risk of presenting with CKD compared to uninfected individuals (risk ratio = 1.23; 95% CI: 1.12–1.34). Results were similar by study type, for cohorts (HR = 1.26; 95% CI: 1.12–1.40) and cross‐sectional studies (OR = 1.21; 95% CI: 1.09–1.32). Country‐stratified analysis demonstrated a significantly increased risk between HCV and CKD in the Taiwanese subgroup (risk ratio = 1.28; 95% CI: 1.12–1.34) and the US subgroup (risk ratio = 1.17; 95% CI: 1.01–1.32). Egger regression revealed no evidence of publication bias. HCV infection is associated with a greater risk of developing and progression of CKD compared to uninfected controls.
Genomic variation across landscapes: insights and applications
Authors: Bragg Jason G. , Supple Megan A. , Andrew Rose L. , Borevitz Justin O.
Published: April 2015

The distribution of genomic variation across landscapes can provide insights into the complex interactions between the environment and the genome that influence the distribution of species, and mediate phenotypic adaptation to local conditions. High throughput sequencing technologies now offer unprecedented power to explore these interactions, allowing powerful inferences about historical processes of colonization, gene flow and divergence, as well as the identification of loci that mediate local adaptation. These ‘landscape genomic’ approaches have been validated in model species and are now being applied to nonmodel organisms, including foundation species that have substantial effects on ecosystem processes. Here we review the growing field of landscape genomics from a very broad perspective. In particular, we describe the inferential power that is gained by taking a genome‐wide view of genetic variation, strategies for study design to best capture adaptive variation, and how to apply this information to practical challenges, such as restoration.

Contents

Summary
953

I.
Introduction
953

II.
Definitions
955

III.
Model species for landscape genomics
955

IV.
What new insights does genomics provide?
956

V.
How can we best unlock the potential of genomics on landscapes?
960

VI.
Prospects and conclusions
963

Acknowledgements
964

References
964
Moisture rivals temperature in limiting photosynthesis by trees establishing beyond their cold‐edge range limit under ambient and warmed conditions
Authors: Moyes Andrew B. , Germino Matthew J. , Kueppers Lara M.
Published: April 2015

Climate change is altering plant species distributions globally, and warming is expected to promote uphill shifts in mountain trees. However, at many cold‐edge range limits, such as alpine treelines in the western United States, tree establishment may be colimited by low temperature and low moisture, making recruitment patterns with warming difficult to predict.

We measured response functions linking carbon (C) assimilation and temperature‐ and moisture‐related microclimatic factors for limber pine (Pinus flexilis) seedlings growing in a heating × watering experiment within and above the alpine treeline. We then extrapolated these response functions using observed microclimate conditions to estimate the net effects of warming and associated soil drying on C assimilation across an entire growing season.

Moisture and temperature limitations were each estimated to reduce potential growing season C gain from a theoretical upper limit by 15–30% (c. 50% combined). Warming above current treeline conditions provided relatively little benefit to modeled net assimilation, whereas assimilation was sensitive to either wetter or drier conditions.

Summer precipitation may be at least as important as temperature in constraining C gain by establishing subalpine trees at and above current alpine treelines as seasonally dry subalpine and alpine ecosystems continue to warm.
miR‐200c/Bmi1 axis and epithelial–mesenchymal transition contribute to acquired resistance to BRAF inhibitor treatment
Authors: Liu Shujing , Tetzlaff Michael T. , Wang Tao , Yang Ruifeng , Xie Lin , Zhang Gao , Krepler Clemens , Xiao Min , Beqiri Marilda , Xu Wei , Karakousis Giorgos , Schuchter Lynn , Amaravadi Ravi K. , Xu Weiting , Wei Zhi , Herlyn Meenhard , Yao Yuan , Zhang Litao , Wang Yingjie , Zhang Lin , Xu Xiaowei
Published: April 2015

Resistance to BRAF inhibitors (BRAFi) is one of the major challenges for targeted therapies for BRAF‐mutant melanomas. However, little is known about the role of microRNAs in conferring BRAFi resistance. Herein, we demonstrate that miR‐200c expression is significantly reduced whereas miR‐200c target genes including Bmi1, Zeb2, Tubb3, ABCG5, and MDR1 are significantly increased in melanomas that acquired BRAFi resistance compared to pretreatment tumor biopsies. Similar changes were observed in BRAFi‐resistant melanoma cell lines. Overexpression of miR‐200c or knock‐down of Bmi1 in resistant melanoma cells restores their sensitivities to BRAFi, leading to deactivation of the PI3K/AKT and MAPK signaling cascades, and acquisition of epithelial–mesenchymal transition‐like phenotypes, including upregulation of E‐cadherin, downregulation of N‐cadherin, and ABCG5 and MDR1 expression. Conversely, knock‐down of miR‐200c or overexpression of Bmi1 in BRAFi‐sensitive melanoma cells activates the PI3K/AKT and MAPK pathways, upregulates N‐cadherin, ABCG5, and MDR1 expression, and downregulates E‐cadherin expression, leading to BRAFi resistance. Together, our data identify miR‐200c as a critical signaling node in BRAFi‐resistant melanomas impacting the MAPK and PI3K/AKT pathways, suggesting miR‐200c as a potential therapeutic target for overcoming acquired BRAFi resistance.
Comparison of tuberculin skin test and QuantiFERON®‐TB Gold In‐Tube for the diagnosis of childhood tuberculosis
Authors: Uzunhan Ozan , Törün Selda Hançerli , Somer Ayper , Salman Nuran , Köksalan Kaya
Published: April 2015

Background

Tuberculosis (TB) is an important worldwide ongoing health issue. To be able to control TB, one should not only cure active TB but also identify childhood TB patients who have the possibility to develop active disease in the future. The aim of this study was to compare a century‐old tuberculin skin test (TST) and QuantiFERON‐TB Gold In‐Tube (QFT‐GIT) test, developed as an alternative to TST and which has been claimed to be superior to TST in several ways, in the diagnosis of childhood TB.

Methods

Fifty‐three children with TB between 5 months and 17.5 years of age and 92 healthy children from the same age group with no risk factors for TB were recruited into the study. All children underwent TST and QFT‐GIT test and their demographic, clinic and laboratory data were recorded. Data were analyzed using SPSS 14.

Results

A total of 53 patients were diagnosed with TB. Mean patient age was 8.5 ± 4.3 years (range, 5 months–17.5 years). A total of 41.7% of the patients were female. Sixteen of 53 patients had confirmation on culture. QFT‐GIT test was positive in 16 and TST was positive in 15 among 16 children with culture‐confirmed TB. The sensitivity of TST and QFT‐GIT were 93.8% and 100.0%, and the specificity of TST and QFT‐GIT were 100.0% and 97.8%, respectively. With regard to the 53 TB children including those without bacteriological confirmation, QFT‐GIT was positive in 33 children, and TST was positive in 44 children. The sensitivity of TST and QFT‐GIT was then 83.0% and 62.3%, and the specificity, 100.0% and 97.8%, respectively.

Conclusion

Although positive QFT‐GIT test is very significant for TB, negative results will not exclude TB infection. TST and QFT‐GIT used together may provide more efficient results.
HRCT of fibrosing lung disease
Authors: Jacob Joseph , Hansell David M.
Published: April 2015

The use of high‐resolution computed tomography (HRCT) has brought increased diagnostic discrimination to the evaluation of lung disease, particularly fibrosing lung diseases. Once the presence of a predominantly fibrosing lung disease has been established on evaluation of a HRCT, a stepwise approach is proposed that can refine the potential HRCT diagnoses from a list of over 100 different interstitial lung diseases to one of only five fibrosing lung diseases. Within the category of the fibrosing lung diseases, the recognition of idiopathic pulmonary fibrosis (IPF) is key. IPF is the most prevalent idiopathic interstitial pneumonia and has a mortality greater than any of the other diffuse lung diseases. Several diagnostic dilemmas are explored including challenges with the recent IPF diagnosis and management guidelines (2011), as well as with the ‘difficult to characterize’ fibrosing diseases such as smoking‐related lung fibrosis, unclassifiable disease and acute exacerbations of fibrosing lung disease.
Externalities of National Pharmaceutical Policy when Markets are Integrated through Parallel Trade
Authors: Birg Laura
Published: April 2015

This paper studies externalities of nationally determined cost‐sharing systems, in particular coinsurance rates, under pharmaceutical parallel trade in a two‐country model with a vertical distributor relationship. Parallel trade generates a price‐decreasing competition effect in the destination country of the parallel import and a price‐increasing double marginalization effect in the source country. An increase of the coinsurance rate in the destination country mitigates the double marginalization effect in the source country. An increase of the coinsurance rate in the source country reinforces the competition effect in the destination country. This may be a case for policy coordination in the European Union.
Nationalism and Linguistic Purism in ContemporaryJapan: National Sentiment Expressed through Public Attitudes towards Foreignisms
Authors: Hosokawa Naoko
Published: April 2015

Linguistic purism is a term that refers to the urge to preserve a ‘desirable’ language form while eliminating ‘undesirable’ linguistic elements – a drive profoundly intertwined with nationalism. A particularly salient manifestation of this phenomenon is the controversy on the use of foreign loanwords. This article examines the contrasting expressions and metaphors used to describe the national language and foreignisms found in newspaper articles published in contemporaryJapan and argues that the growing tendency to discuss national language in contrast to foreignisms can be understood as a particular manifestation of ongoing (re)negotiation of national identity. Criticisms and praises of the use of loanwords are found to be grounded upon a desire to establish specific understandings of Japaneseness in reference to the otherness felt within a society that is symbolized by loanwords, constructing an ‘internal Other’ to a Japanese ‘Self’, the identity of which is neither autonomous nor clearly delineated.
Blinded by Beauty? Physical Attractiveness and Candidate Selection in the U.S. House of Representatives
Authors: Stockemer Daniel , Praino Rodrigo
Published: April 2015

Objective

In this article we show that physical attractiveness matters as a heuristic device for uninformed voters but not for politically savvy voters.

Methods

Drawing on a two‐step experiment, we first ask over 100 students to rank the physical attractiveness of candidates to the U.S. House of Representatives. Second, we create a treatment and a control group comprising each of 1,200 research different subjects. We ask the first group to indicate their vote choice by merely looking at the picture of candidates for the 2008 U.S. House of Representatives elections, while the second group has a picture and a detailed description of the political/professional competence of the contenders at their disposal.

Results

We find that our first group of study subjects representing all those voters who are politically uninformed tend to cast their ballot for the better‐looking candidate, whereas the second group, representing politically knowledgeable individuals, choose the more competent candidate.

Conclusion

Our experimental study provides evidence that uninformed or politically unknowledgeable voters use political appearance as a heuristic device in casing their ballot at elections.
A resource for characterizing genome‐wide binding and putative target genes of transcription factors expressed during secondary growth and wood formation in Populus
Authors: Liu Lijun , Ramsay Trevor , Zinkgraf Matthew , Sundell David , Street Nathaniel Robert , Filkov Vladimir , Groover Andrew
Published: April 2015

Identifying transcription factor target genes is essential for modeling the transcriptional networks underlying developmental processes. Here we report a chromatin immunoprecipitation sequencing (ChIP‐seq) resource consisting of genome‐wide binding regions and associated putative target genes for four Populus homeodomain transcription factors expressed during secondary growth and wood formation. Software code (programs and scripts) for processing the Populus ChIP‐seq data are provided within a publically available iPlant image, including tools for ChIP‐seq data quality control and evaluation adapted from the human Encyclopedia of DNA Elements (ENCODE) project. Basic information for each transcription factor (including members of Class I KNOX, Class III HD ZIP, BEL1‐like families) binding are summarized, including the number and location of binding regions, distribution of binding regions relative to gene features, associated putative target genes, and enriched functional categories of putative target genes. These ChIP‐seq data have been integrated within the Populus Genome Integrative Explorer (PopGenIE) where they can be analyzed using a variety of web‐based tools. We present an example analysis that shows preferential binding of transcription factor ARBORKNOX1 to the nearest neighbor genes in a pre‐calculated co‐expression network module, and enrichment for meristem‐related genes within this module including multiple orthologs of Arabidopsis KNOTTED‐like Arabidopsis 2/6.
Impacts of cropping system and management practices on the assembly of weed communities
Authors: Barroso J , Miller Z J , Lehnhoff E A , Hatfield P G , Menalled F D
Published: April 2015

Understanding how weed communities assemble as a function of biotic and abiotic filters and transform through time has important implications for the sustainable management of agronomic systems. In a three‐year study, we evaluated weed community responses to lucerne (Medicago sativa, perennial) vs. continuous spring wheat (Triticum aestivum, annual, CSW) and weed management practices where weeds in the CSW system were managed with three contrasting approaches (herbicide, tillage or sheep grazing). Our results indicated no differences in weed diversity between the perennial and annual crops or across the different management practices in CSW. However, there were differences in weed community composition. Lucerne, with the exception of the establishing year, impeded the growth and reproduction of several annual weeds, including Amaranthus retroflexus, Thlaspi arvense, Lamium amplexicaule and Chenopodium album, but favoured perennial broad‐leaved weeds such as Taraxacum officinale and Cirsium arvense. The replacement of herbicide treatments in pre‐plant and post‐harvest in CSW with soil tillage or sheep grazing selected for different weed communities beyond the second year of establishment. The weed species driving the differences in CSW systems were Androsace occidentalis, more common in CSW managed chemically; Asperugo procumbens, more common in CSW managed with tillage; and T. officinale and Lactuca serriola, more common in CSW managed with sheep grazing. Understanding how cropping systems modify weed communities is a necessary step to shift from reactive weed control programmes to predictive management strategies.
Oxygen Enriched Air Effects on Combustion, Emission, and Distributed Reaction
Authors: Said Ahmed O. , Gupta Ashwani K.
Published: April 2015

A novel combustion technology which combines colorless distributed combustion (CDC) and oxygen enriched combustion (OEC) air is examined to achieve optimum benefits of both technologies and to foster novel technologies for cleaner environment. The influence of oxygen enriched air–methane flames under nonpremixed and premixed fuel-lean combustion conditions is examined with focus on emission of NO and CO, combustor exit temperature (Texit), and distribution of reaction zone in the combustor using OH* chemiluminescence intensity distribution. A cylindrical combustor was used at combustion intensity of 36 MW/m3·atm and heat load of 6.25 kW. Results are also reported with normal air (21% oxygen). Oxygen enrichment provided stable combustion operation at lower equivalence ratios than normal air and also reduced CO emission. Increase in oxygen concentration from 21% to 25% or 30% increased the NO and decreased CO emissions at all the equivalence ratios examined. Using 30% O2 enriched air in premixed case showed NO emissions of 11.4 ppm and 4.6 ppm at equivalence ratios of 0.5 and 0.4, respectively. Oxygen enrichment also reduced CO emission to 38 ppm at equivalence ratio of 0.5. Operating the combustor with normal air at these equivalence ratios resulted in unstable combustion. OH* chemiluminescence revealed increased intensity with the reaction zone to shift upstream at increased oxygen concentration. The exhaust temperature of the combustor increased with oxygen enrichment leading to lower CO concentration and increased combustion efficiency. The oxidizer injected at higher velocities moved the reaction zone to upstream location with simultaneous reduction of both NO and CO, specifically under nonpremixed combustion.
Feasibility of Waterflooding for a Carbonate Oil Field Through Whole-Field Simulation Studies
Authors: Yue Wenting , Yilin Wang John
Published: April 2015

The carbonate oil field studied is a currently producing field in U.S., which is named “PSU” field to remain anonymity. Discovered in 1994 with wells on natural flow or through artificial lift, this field had produced 17.8 × 106 bbl of oil to date. It was noticed that gas oil ratio had increased in certain parts and oil production declined with time. This study was undertaken to better understand and optimize management and operation of this field. In this brief, we first reviewed the geology, petrophysical properties, and field production history of PSU field. We then evaluated current production histories with decline curve analysis, developed a numerical reservoir model through matching production and pressure data, then carried out parametric studies to investigate the impact of injection rate, injection locations, and timing of injection, and finally developed optimized improved oil recovery (OIR) methods based on ultimate oil recovery and economics. This brief provides an addition to the list of carbonate fields available in the petroleum literature and also improved understandings of Smackover formation and similar analogous fields. By documenting key features of carbonated oil field performances, we help petroleum engineers, researchers, and students understand carbonate reservoir performances.
Lattice Rotation Patterns and Strain Gradient Effects in Face-Centered-Cubic Single Crystals Under Spherical Indentation
Authors: Gao Y. F. , Larson B. C. , Lee J. H. , Nicola L. , Tischler J. Z. , Pharr G. M.
Published: April 2015

Strain gradient effects are commonly modeled as the origin of the size dependence of material strength, such as the dependence of indentation hardness on contact depth and spherical indenter radius. However, studies on the microstructural comparisons of experiments and theories are limited. First, we have extended a strain gradient Mises-plasticity model to its crystal plasticity version and implemented a finite element method to simulate the load–displacement response and the lattice rotation field of Cu single crystals under spherical indentation. The strain gradient simulations demonstrate that the forming of distinct sectors of positive and negative angles in the lattice rotation field is governed primarily by the slip geometry and crystallographic orientations, depending only weakly on strain gradient effects, although hardness depends strongly on strain gradients. Second, the lattice rotation simulations are compared quantitatively with micron resolution, three-dimensional X-ray microscopy (3DXM) measurements of the lattice rotation fields under 100 mN force, 100 μm radius spherical indentations in 〈111〉, 〈110〉, and 〈001〉 oriented Cu single crystals. Third, noting the limitation of continuum strain gradient crystal plasticity models, two-dimensional discrete dislocation simulation results suggest that the hardness in the nanocontact regime is governed synergistically by a combination of strain gradients and source-limited plasticity. However, the lattice rotation field in the discrete dislocation simulations is found to be insensitive to these two factors but to depend critically on dislocation obstacle densities and strengths.
Elastic Properties of Human Osteon and Osteonal Lamella Computed by a Bidirectional Micromechanical Model and Validated by Nanoindentation
Authors: Korsa Radim , Lukes Jaroslav , Sepitka Josef , Mares Tomas
Published: April 2015

Knowledge of the anisotropic elastic properties of osteon and osteonal lamellae provides a better understanding of various pathophysiological conditions, such as aging, osteoporosis, osteoarthritis, and other degenerative diseases. For this reason, it is important to investigate and understand the elasticity of cortical bone. We created a bidirectional micromechanical model based on inverse homogenization for predicting the elastic properties of osteon and osteonal lamellae of cortical bone. The shape, the dimensions, and the curvature of osteon and osteonal lamellae are described by appropriately chosen curvilinear coordinate systems, so that the model operates close to the real morphology of these bone components. The model was used to calculate nine orthotropic elastic constants of osteonal lamellae. The input values have the elastic properties of a single osteon. We also expressed the dependence of the elastic properties of the lamellae on the angle of orientation. To validate the model, we performed nanoindentation tests on several osteonal lamellae. We compared the experimental results with the calculated results, and there was good agreement between them. The inverted model was used to calculate the elastic properties of a single osteon, where the input values are the elastic constants of osteonal lamellae. These calculations reveal that the model can be used in both directions of homogenization, i.e., direct homogenization and also inverse homogenization. The model described here can provide either the unknown elastic properties of a single lamella from the known elastic properties at the level of a single osteon, or the unknown elastic properties of a single osteon from the known elastic properties at the level of a single lamella.
Dynamic Properties of Tympanic Membrane in a Chinchilla Otitis Media Model Measured With Acoustic Loading
Authors: Yokell Zachary , Wang Xuelin , Gan Rong Z.
Published: April 2015

Otitis media is the most common infectious disease in young children, which results in changes in the thickness and mechanical properties of the tympanic membrane (TM) and induces hearing loss. However, there are no published data for the dynamic properties of the TM in otitis media ears, and it is unclear how the mechanical property changes are related to TM thickness variation. This paper reports a study of the measurement of the dynamic properties of the TM in a chinchilla acute otitis media (AOM) model using acoustic loading and laser Doppler vibrometry (LDV). AOM was created through transbullar injection of Haemophilus influenzae into the middle ear, and AOM samples were prepared 4 days after inoculation. Vibration of the TM specimen induced by acoustic loading was measured via LDV over a frequency range of 0.1–8 kHz. The experiment was then simulated in a finite element (FE) model, and the inverse-problem solving method was used to determine the complex modulus in the frequency domain. Results from 12 ears (six control and six AOM) show that the storage modulus of the TM from AOM ears was on average 53% higher than that of control ears, while the loss factor was 17.3% higher in control ears than in AOM ears at low-frequency (f < 1 kHz). At high-frequency (e.g., 8000 Hz), there was a mean 40% increase in storage modulus of the TM from AOM compared to control samples. At peak frequency (e.g., 3 kHz), there was a 19.5% increase in loss factor in control samples compared to AOM samples. These findings quantify the changes induced by AOM in the chinchilla TM, namely, a significant increase in both the storage and loss moduli.
Low-Temperature Sintering of ZnO–TiO2 Ceramics
Authors: Nie Zhengwei , Lin Yuyi , Wang Feixue
Published: April 2015

Vanadium pentoxide (V2O5) was chosen as a sintering aid to lower the sintering temperature of the ZnO–TiO2 system. The effect of V2O5 on the sintering behavior and material properties of ZnO–TiO2 ceramics and cermets made of ZnO–TiO2 ceramics and copper (Cu) was investigated as a function of V2O5 percentage and sintering temperature. Densities and hardness of the specimens were improved with an increase of V2O5 up to 2 wt. %. The sintering temperature of the specimens can be reduced to below 1000 °C. The properties of ZnO–TiO2 ceramics and cermets made from ZnO–TiO2 ceramics and Cu with V2O5 are strongly dependent on the sintering temperature. The density of ZnO–TiO2 ceramics and cermets was increased up to 95%, 90% of theoretical density at 900–920 °C, 960–1000 °C, respectively, for 4 hrs.
Noise Control of Marine Gas Turbines in Propulsion and Auxiliary Power Applications
Authors: Schiff M. I.
Published: April 2015

While techniques for silencing gas turbines have been applied with great success to numerous land systems, only limited experience has been gained aboard ship. The silencing of ship board gas turbines is made more complex due to the unique problems imposed by the effects of a sea air environment as well as the necessity for minimization of dead load and limitations on available space. The purpose of this paper is to review the state-of-the-art in gas turbine silencing specifically in relation to marine applications. Experiences in silencing the main propulsion system aboard the Adm. Wm. M. Callaghan, Military Sea Transport Service Roll-On/Roll-Off Cargo Ship and the Auxiliary Power units aboard the Royal Canadian DDH-280 Destroyers are described.
The Use of Desk Top Computers in the Teaching of Aircraft Gas Turbines
Authors: Oates G. C.
Published: April 2015

The fairly recent advent of programmable desk top computers with branching and looping capability has allowed the simple and rapid handling of otherwise very complicated engineering problems. The teaching of aircraft gas turbines is particularly enhanced by the use of such computers because remarkably accurate performance calculations, design calculations or flow field calculations can be made on such machines. The rapid calculation capability of the computer frees the student to concern himself with the implications of the results, rather than with the minutia of the calculations. Four specific example programs and results are given: (a) Design calculations for a turbojet; (b) Design calculations for a fan jet, in which the bypass ratio is optimized to give minimum specific fuel consumption; (c) Performance calculations for both a conventional turbojet and a variable area turbojet; (d) Flow field calculations for a highly loaded actuator disk.
Gas Turbine Applications for Railcar in Japan
Authors: Takita S.
Published: April 2015

In 1967, IHI engaged in developing a gas turbine for high speed railcars as an industrial application of the aero gas turbine CT58. Since then, IM100-1R and IM100-2R engines, derived from CT58’s, have been tested on the bench and on experimental railcars by the Japanese Rolling Stock Manufacturers association (JRSMA) and the Japan National Railway (JNR). In this paper, a brief history of development tests for gas turbine railcars, problems and improvements in applications of the IM100-1R and -2R for prime mover of the railcar are described.
The British Leyland 2S/350/R Gas Turbine Engine
Authors: Barnard M. C. S. , Phillips P. A.
Published: April 2015

Experience gained on a number of gas turbine powered heavy trucks indicated that the conventional engine configuration could be considerably improved. Aspects of engine reliability, and access to the heat exchangers and vehicle ancilliaries led to the desirability of an alternative engine layout. At the same time, development of components reached the stage where further performance improvements were hampered by engine constraints — for example, the ducting between the compressor and the heat exchangers, and the size and distribution of the accessory loads. The most satisfactory solution to these requirements has been to adopt a single heat exchanger engine concept, since this also showed a considerable reduction in engine cost while the fuel consumption penalty is only marginal in practice. The resultant engine is described, giving significant design features and performance data.
Impact of Alternate Fuels on Stationary Gas Turbine Operations and Siting
Authors: Lipfert F. W.
Published: April 2015

An analysis of gas turbine ambient air quality impact is presented, from the standpoint of the acceptability of alternate fuels having higher sulfur content and possibly higher particulate emissions. Various plume rise formulas are compared, and formulas are given for maximum ground level concentrations for both short term (1 to 3 hr) and intermediate (3 to 24 hr) periods. The results show that the U.S. Federal Air quality standards may allow large gas turbine complexes (∼500 mw) burning up to 1% sulfur fuel, for example. Taking advantage of this capability could increase the supply of lower sulfur fuels for home heating and/or transportation use.
Curvature Effects on a Turbine Blade Cooling Film
Authors: Nicolas J. , Le Meur A.
Published: April 2015

Analysis of the equations governing the equilibrium conditions of a cool gas film injected along a curved wall in a hot gas stream shows that Archimedes type forces may either increase or decrease the cooling efficiency of the film, according to the value of the mass flow rate ratio, the temperature ratio of the flows and the sign of the curvature of the wall. Experiments have been performed to verify these predictions: in the case of a concave wall and relatively high mass flow rate ratios, a gain in performance has been obtained, if compared to the constant pressure flat plate; in the case of a convex wall, the cooling efficiency of the film is less than that of a film on a plate with the same pressure gradient, although it is still higher, for the same mass flow ratio than the efficiency of a film on a constant pressure plate.
Controllable Pitch Propellers in the DD-963: A Status Report
Authors: Ridley D. E. , Case R. C.
Published: April 2015

United States seapower in the 70’s is synonymous with a new class of destroyers developed to maintain America’s strength on the world’s seas. When the DD963 joins the fleet in 1974, she will be unlike any destroyer ever to fly the United States flag. She will be bigger, faster, and more sophisticated. As a vital part of the main propulsion plant of this ship, controllable pitch propellers were used in conjunction with marine gas turbines. This paper addresses the description and operation of the CP propellers, and various improvements in the “state of the art” of propeller design and manufacture which have been incorporated in the ship.
Simplified Brayton Cycle Calculations for a Low BTU-Fueled Gas Turbine
Authors: Sullivan D. A.
Published: April 2015

A simplified thermodynamic cycle analysis for a simple cycle, low Btu fueled gas turbine with air extraction is derived. The analysis extends the simple “air cycle” analysis to include pressure losses, combustor efficiency, compressor discharge air extraction (or mass injection) and fuel mass addition without adding appreciable complexity to the equations. A parametric study with this analysis shows the enormous gains in output and efficiency possible with low Btu gaseous fuels if the gas turbine is not required to compress the fuel gas.
High Efficiency Gas Turbine/Organic Rankine Cycle Combined Power Plant
Authors: Morgan D. T. , Davis J. P.
Published: April 2015

The use of an organic Rankine cycle system operating on the exhaust heat from a gas turbine results in a very significant improvement in the combined plant efficiency. For example, a current technology regenerated gas turbine with 36.6 percent efficiency, is improved to 47.1 percent by addition of the organic Rankine cycle bottoming plant. It has been determined that, because of the desirable thermodynamic properties of selected organic working fluids, the organic bottoming cycle invariably results in a substantially higher efficiency than the equivalent steam bottoming cycle. In addition, the non-corrosive properties of the organic working fluid, coupled with its desirable turbine expansion characteristics, results in a competitive capital cost. Preliminary studies indicate that the complete organic system cost is in the vicinity of $150/kwe from the organic system. For a base-loaded combined plant, the organic bottoming plant is estimated to produce power at an incremental cost of 0.370¢/kwhre.
Supersonic Cascade Interaction
Authors: Lichtfuss H. J. , Starken H.
Published: April 2015

The supersonic flow adjustment between two interacting blade rows is predicted theoretically. One of both cascades may have a constant velocity in the circumferential direction. The calculation is carried out in a quasi-stationary manner. This represents an exact solution if the constant inlet and outlet flow conditions are solely under the scope of view. Admitting the above assumptions it is possible to calculate the uniform outlet flow of the first and the associated inlet flow of the second cascade as a function of the circumferential velocity. Quantitative results are presented for flat plate cascades. However, the method is not at all restricted to these simple cases.
Supplementary Analytical Procedures for Evaluating Fuel Handling Characteristics of Heavy Distillate Gas Turbine Fuels
Authors: Barry E. G. , Cauley S. P.
Published: April 2015

The use of heavy distillates in gas turbines used for electric power generation is expected to increase in the United States and special analytical procedures have been developed to assist in evaluating the handling characteristics of these fuels. Data obtained on wax melting temperatures, and energy required, for a number of different heavy distillate fuels are presented. Special hot filtration method for measuring non-wax fuel sediment is also described.
NEPCOMP: The Navy Engine Performance Program
Authors: Shapiro S. R. , Caddy M. J.
Published: April 2015

A general purpose computer program is described which permits rapid design point and off-design performance analyses of air breathing engines. The modular approach used in building the over-all program allows analysis of many engine configurations including multi-stream, multi-nozzle, augmented engines, shaft engines and ramjets. The program may be operated with or without component maps. The result is a computational tool that can be used to perform independent analyses of an engine manufacturer’s product as well as provide engine performance data for use in engine-airframe design and integration studies.
The Application of Explosive Welding to Turbine Components
Authors: Linse V. D.
Published: April 2015

In recent years, developments in the explosive welding process have demonstrated that the process has many areas of application in the turbine field. This is a result of the process’s capability to weld a wide variety of the metals and alloys which are being utilized in turbines as well as recent applications of the process to fabricate complex shapes and structures which are often encountered in turbine components. This paper describes the successful application of explosive welding to actual turbine components as well as areas in which the process has potential for application in the future. Applications included in the paper include the repair of damaged bearings and shafts, application of protective claddings to selected areas, fabrication of complex channelled structures, and the welding of laminated structures.
Swirl-Can Combustor Performance to Near-Stoichiometric Fuel-Air Ratio
Authors: Diehl L. A. , Biaglow J. A.
Published: April 2015

Emissions and performance characteristics were determined for two full-annulus swirl-can modular combustors operated to near-stoichiometric fuel air ratios. The purposes of the tests were to obtain stoichiometric data at inlet-air temperatures up to 894 K and to determine the effect of module number by investigating 120 and 72 module swirl-can combustors. The maximum average exit temperature obtained with the 120-module swirl-can combustor was 2465 K with a combustion efficiency of 95 percent at an inlet-air temperature of 894 K. The 72-module swirl-can combustor reached a maximum average exit temperature of 2306 K with a combustion efficiency of 92 percent at an inlet-air temperature of 894 K. At a constant inlet air temperature, maximum oxides of nitrogen emission index values occurred at a fuel-air ratio of 0.037 for the 72-module design and 0.044 for the 120-module design. The combustor average exit temperature and combustion efficiency were calculated from emissions measurements. The measured emissions included carbon monoxide, unburned hydrocarbons, oxides of nitrogen, and smoke.
Gas Turbine Cycles for the Process Industry
Authors: Boyce M. P. , Elchuri V. , Trevillion W. L. , Wohlschlegel D. H.
Published: April 2015

The paper describes various gas turbine cycles which are practical from a process industry standpoint. Several cycles and their actual applications in the field have been dealt with in detail. These cycles should make the gas turbine a more competitive driver for the process industry.
“Do It Yourself” Maintenance: An On Site Approach to Lower Costs and Improved Equipment Availability
Authors: Cigal A. L.
Published: April 2015

The greater utilization of “On Site” Gas Turbine repair techniques is a process whereby utilities can profit from a 20 to 50 percent reduction in Maintenance Costs, combined with an availability factor of better than 97 percent. The expertise gained by Utility personnel is further reflected in a major awareness of and the application of preventive maintenance practices resulting in additional cost and efficiency benefits.
The Application of Gas- and Oil-Lubricated Foil Bearings for the ERDA/Chrysler Automotive Gas Turbine Engine
Authors: Gray S. , Sparks N. , McCormick J.
Published: April 2015

A design study has been made of a resilient hydrodynamic foil bearing support system for a 58,500-rpm automotive gas turbine rotor utilizing an air-lubricated journal bearing at the hot turbine end and an oil-lubricated journal and thrust bearing at the compressor end. The paper includes a review of earlier engine rotor/bearing systems and lists the potential advantages of the foil bearings. Design analysis of the bearings and rotordynamics is given including critical speeds, rotor unbalance response, bearing performance, and temperature distributions to confirm the feasibility. The study shows that potential improvements to the overall system in terms of cost savings, reliability, and performance are possible. Full-scale dynamic simulator testing of the rotor bearing system as designed is in progress.
Advancements and Application of Programmable Analog Control Technology
Authors: Dent J. R. , Le Fevre H. P.
Published: April 2015

The advantage of rapid control system adjustment is assuming increasing importance in the development of automotive gas turbine engine development. Digitally programmed analog controllers are particularly suited to these purposes, and the basis of operation of controllers of this type is explained. The detailed operation of an early development controller, type PAC 120, is described briefly and the operational short-comings of the unit are discussed. The incorporation of features 10 provide an improved unit, type PAC 250, having significant increase in capability is examined and the resultant controller is described. The application of the PAC 120 to some selected control problems of an automotive turbine engine are described. Finally, the application of the PAC 250 controller to the complete control of the power plant, including start-up and shutdown of the engine, is examined. It is concluded that the programmable analog control concept is a uniquely powerful development tool for this type of application.
Problems Associated With Cold Weather Operation of Gas Turbines
Authors: Dickson J.
Published: April 2015

The operation of gas turbines during conditions of extreme cold weather can present a variety of problems. Foremost among these problems is the potential for snow and ice buildup in the air intake system which can cause restrictions or interruptions in operation and possible ingestion damage to the axial compressor section of the gas turbine. Other cold weather operating problems include cold lubricating oil and oil system blockages following periods of shutdown. Major maintenance on the equipment becomes very difficult, if not impossible, during conditions of extremely cold weather unless the work can be carried out in an adequately heated building. This paper expands on these problems and others and outlines methods which have been developed to deal with them. Its content could be of benefit to design engineers engaged in preparing specifications for gas turbine equipment to be used in cold climates.
Propulsion Gear Units for Gas Turbine Naval Installations
Authors: Hepper J.
Published: April 2015

The gas turbine is established as a Naval Marine propulsion power unit and the number of ships at sea using the high power gas turbine in association with diesel engines, smaller gas turbine or steam turbine is increasing. Gear unit designs have been evolved to meet the conditions dictated by the engine/propeller shaft positions and the requirements of ship designers. The involvement of the gear designer in the analysis of shaft vibration characteristics is accepted, and the advantage of costly shore testing has been proven in that design modifications could be difficult and expensive to carry out during trials.
Type 3 — Sulzer’s New 5 MWE Gas Turbine
Authors: Beglinger V. , Zerlauth F.
Published: April 2015

This paper describes Sulzer’s new Type 3 gas turbine. This machine is designed for quantity production in single- and split-shaft versions with ratings from 5350 to 6200 kw. The basic arrangement of the unit as a whole and of the machine package are presented, based on the requirements of the general specification. Design and construction of the machine are then described. The paper ends with a section on auxiliary systems and possible plant layouts.
Advanced Acoustic Nacelle Concepts
Authors: Painter G. W.
Published: April 2015

The results of a recently completed study on the potential noise-reduction benefits that could be derived from the development of an “Advanced Acoustic-Composite Nacelle” for future subsonic commercial transports are discussed. In this study, noise-reduction objectives were based on the acceptance of noise floors imposed by airframe noise during approach operation and jet noise during takeoff. The reduction of treatable source levels to these floors should result in aircraft noise levels below those of the already quiet current widebodied transports. It is predicted that the foregoing noise levels can be achieved in future widebodied transports by employing advanced acoustical duct liners, extending the (lined) fan duct, and incorporating jet mixing.