bluuebunny/crossref_metadata_2025 huggingface dataset:
The Relationship between Tectonic Subsidence and BSR of Upper Neogene in the Deep‐Water Area of the Northern Continental Slope, South China Sea
Authors: Xinghe YU , Jianzhong WANG , Shengli LI , Jingnan FANG , Longyan JIANG , Xiaorong CONG , Jinqiang LIANG , Zhibin SHA
Published: July 2013

BSR (Bottom Simulating Reflector) occurs widely in the strata since the late Miocene in the deep‐water area of the northern continental slope of South China Sea (SCS). It is an important seismic reference mark which identifies the gas hydrate and its distribution influenced by the tectonic movements. Single‐point basin modeling was conducted using 473 points in the study area. To discuss the relationships between the tectonic subsidence and BSR, the volume and rate of tectonic subsidence in each geological time have been simulated. The results show that there are three tectonic accelerate subsidence processes in the study area since the late Miocene, especially since 1.8Ma the tectonic subsidence accelerates more apparently. Since the Late Miocene to Pleistocene, the rate of tectonic subsidence in deep‐water underwent a transformation from weak to strong. The ratio of tectonic subsidence to the total subsidence was relatively high (65–70%). Through the superposition of the BSR developed areas and the contours of tectonic subsidence in this area, it was discovered that more than 80% of BSR tend to be distributed at the slope break or depression‐uplift structural transfer zone and the average tectonic subsidence rate ranges from 70 m/Ma to 125 m/Ma.
Akt regulates TPP1 homodimerization and telomere protection
Authors: Han Xin , Liu Dan , Zhang Yi , Li Yujing , Lu Weisi , Chen Junjie , Songyang Zhou
Published: July 2013

Telomeres are specialized structures at the ends of eukaryotic chromosomes that are important for maintaining genome stability and integrity. Telomere dysfunction has been linked to aging and cancer development. In mammalian cells, extensive studies have been carried out to illustrate how core telomeric proteins assemble on telomeres to recruit the telomerase and additional factors for telomere maintenance and protection. In comparison, how changes in growth signaling pathways impact telomeres and telomere‐binding proteins remains largely unexplored. The phosphatidylinositol 3‐kinase (PI3‐K)/Akt (also known as PKB) pathway, one of the best characterized growth signaling cascades, regulates a variety of cellular function including cell proliferation, survival, metabolism, and DNA repair, and dysregulation of PI3‐K/Akt signaling has been linked to aging and diseases such as cancer and diabetes. In this study, we provide evidence that the Akt signaling pathway plays an important role in telomere protection. Akt inhibition either by chemical inhibitors or small interfering RNAs induced telomere dysfunction. Furthermore, we found that TPP1 could homodimerize through its OB‐fold, a process that was dependent on the Akt kinase. Telomere damage and reduced TPP1 dimerization as a result of Akt inhibition was also accompanied by diminished recruitment of TPP1 and POT1 to the telomeres. Our findings highlight a previously unknown link between Akt signaling and telomere protection.
The developmental trajectory of vocal and event‐related potential responses to frequency‐altered auditory feedback
Authors: Scheerer Nichole E. , Liu Hanjun , Jones Jeffery A.
Published: July 2013

Speech motor control develops gradually as the acoustics of speech are mapped onto the positions and movements of the articulators. In this event‐related potential (ERP) study, children and adults aged 4–30 years produced vocalizations while exposed to frequency‐altered feedback. Vocal pitch variability and the latency of vocal responses were found to differ as a function of age. ERP responses indexed by the P1–N1–P2 complex were also modulated as a function of age. P1 amplitudes decreased with age, whereas N1 and P2 amplitudes increased with age. In addition, a correlation between vocal variability and N1 amplitudes was found, suggesting a complex interaction between behavioural and neurological responses to frequency‐altered feedback. These results suggest that the neural systems that integrate auditory feedback during vocal motor control undergo robust changes with age and physiological development.
Ventral and dorsal visual pathways support auditory motion processing in the blind: evidence from electrical neuroimaging
Authors: Lewald Jörg , Getzmann Stephan
Published: July 2013

Blindness induces processes of neural plasticity, resulting in recruitment of the deafferentated visual areas for non‐visual sensory functions. These processes are related to superior abilities of blind compared with sighted individuals for specific auditory and tactile tasks. Recently, an exceptional performance of the blind has been demonstrated for auditory motion perception, with a minimum audible movement angle that was half that of sighted controls (J. Lewald (2013) Neuropsychologia, 51, 181–186). The present study revealed an electrophysiological correlate of this finding by analysing the so‐called motion‐onset response, a prominent auditory‐evoked potential to the onset of motion. The cN1 component of this response, appearing about 170 ms after motion onset, was two times higher in amplitude for blind compared with matched sighted control subjects. At the time of the cN1, electrical neuroimaging using sLORETA revealed stronger activation in blind than sighted subjects primarily in ventral visual areas (V1v, V2v, VP, V4v) of the right occipital lobe. Activation was also obtained in middle temporal area V5. These findings suggest that blindness results in stronger involvement of both non‐motion areas of the ventral visual stream and motion areas of the dorsal visual stream in processing of auditory motion at the same point in time after motion onset. This argues against the view that visual motion areas, such as area V5, are preferentially recruited for auditory motion analysis in the blind. Rather, cross‐modal reorganization of cortical areas induced by blindness seems to be largely independent of the specific visual functions of the same areas in sighted persons.
The importance of water availability in the reaction equilibrium of hydrolases in forest litters from a Mediterranean area: a study on lipases
Authors: Farnet A.‐M. , Qasemian L. , Gil G. , Ferré E.
Published: July 2013

Water is one of the main variables affecting the carbon cycle (carbon storage or assimilation) in soils or litters from the Mediterranean area, though in most studies it has been considered via soil moisture measurements only. Here, we investigated the effect of water availability as characterized by water activity, aw, on the equilibrium of enzyme reactions (hydrolysis/synthesis) for litters from three species characteristic of the Mediterranean area (Quercus pubescens L, Q. ilex L. and Pinus halepensis L.). Lipases were used as models and an organic phase was used as the reaction medium to adjust water amount. We found that the activities of hydrolysis/transesterification increased with aw, showing that both can occur at the same aw in litter. Furthermore, these lipase activities in litter decreased for aw close to 1, which has been described with purified lipases in organic media, indicating potential enzyme aggregation. Variations in aw with moisture were studied with sorption isotherms, which were found to be similar (isotherm type 2) for all the studied litters. Water activity is a crucial indicator for soils under hydric stress at small water contents, which should be considered for describing more precisely enzyme functioning and giving valuable information about carbon dynamics in soils or litters.
Helicobacter pylori Susceptible/Resistant to Antibiotic Eradication Therapy Differ in the Maturation and Activation of Dendritic Cells
Authors: Kopitar Andreja N. , Skvarc Miha , Tepes Bojan , Kos Janko , Ihan Alojz
Published: July 2013

Background

The natural course of Helicobacter pylori infection, as well as the success of antibiotic eradication is determined by the immune response to bacteria. The aim of the study is to investigate how different Helicobacter pylori isolates influence the dendritic cells maturation and antigen‐presenting function in order to elucidate the differences between Helicobacter pylori strains, isolated from the patients with successful antibiotic eradication therapy or repeated eradication failure.

Materials and Methods

Dendritic cells maturation and antigen presentation were monitored by flow cytometry analysis of the major histocompatibility complex class II (MHC‐II), Toll‐like receptor (TLR) and costimulatory molecules expression, and by determining cytokine secretion.

Results

Dendritic cells stimulated with Helicobacter pylori isolated from patients with repeated antibiotic eradication failure expressed less human leukocyte antigen (HLA‐DR), CD86, TLR‐2, and interleukin‐8 (IL‐8) compared to Helicobacter pylori strains susceptible to antibiotic therapy; the latter expressed lower production of IL‐10. Polymyxin B inhibition of lipopolysaccharide reduces IL‐8 secretion in the group of Helicobacter pylori strains susceptible to antibiotic therapy. The differences in IL‐8 secretion between both groups are lipopolysaccharide dependent, while the differences in secretion of IL‐10 remain unchanged after lipopolysaccharide inhibition. Inhibitor of cathepsin X Mab 2F12 reduced the secretion of IL‐6, and the secretion was significantly lower in the group of Helicobacter pylori strains isolated from patients with repeated antibiotic eradication failure.

Conclusion

Helicobacter pylori strains, susceptible/resistant to antibiotic eradication therapy, differ in their capability to induce DCs maturation and antigen‐presenting function.
OPTIMAL ARBITRATION
Authors: MYLOVANOV TYMOFIY , ZAPECHELNYUK ANDRIY
Published: July 2013

We study common arbitration rules for disputes of two privately informed parties, final offer and conventional arbitration. Conventional arbitration is shown to be an optimal arbitration rule in environments with transferable utility, while final offer arbitration is optimal if utility is nontransferable and the parties’ interests are not too aligned. These results explain the prevalence of both arbitration rules in practice.
Recent advances in robotic surgery in female urology
Authors: Sung Hyun Hwan , Park Bong Hee , Ryu Dong Soo , Lee Kyu Sung
Published: July 2013

Pelvic organ prolapse and lower urinary tract fistulas are two disorders frequently managed in female urology. New techniques have been adapted and improved to decrease morbidity and improve clinical outcomes of these disorders. The adaptation of minimally‐invasive approaches for the management of pelvic organ prolapse and lower urinary tract fistulas began with laparoscopy. However, laparoscopic surgery has not gained widespread popularity as a result of the associated technical challenges, such as intracorporeal suturing and pelvic dissection. Robotic surgery has been widely carried out in urological oncology since 2001, and has been widely adapted because of its advantages over conventional laparoscopy for the management of pelvic organ prolapse and lower urinary tract fistulas. The current literature has shown the safety, feasibility and favorable clinical outcomes of robotic surgery for the treatment of these disorders. Robotic surgery in the management of pelvic organ prolapse and lower urinary tract fistula repairs might offer a promising advancement and benefits. However, further long‐term data should be followed to assess the durability of this newer, and minimally‐invasive approach.
Clinical Validation of Nursing Diagnosis “Parental Role Conflict” in Mothers of Hospitalized Newborns
Authors: Carmona Elenice Valentim , Vale Ianê Nogueira do , Ohara Conceição Vieira da Silva , Abrão Ana Cristina Freitas de Vilhena
Published: July 2013

Objective

To clinically validate the nursing diagnosis, parental role conflict, in mothers of hospitalized newborns.

Method

Fehring's Clinical Validation Model was used, focusing on mothers, using a sample of 83. Major defining characteristics have been defined as the main indicators of the presence of a diagnosis, whereas minor are secondary indicators.

Results

Four minor defining characteristics were identified: (a) “anxiety,” (b) “expresses concerns about changes in maternal role,” (c) “expresses concerns about family,” and (d) “fear.” Major defining characteristics did not occur.

Conclusion

Mothers who spent less time with their infants were the ones that presented a major number of defining characteristics; therefore, they should have more opportunities for being with their babies. Other studies on subjective phenomena are needed.
Epigenetic repression of bone morphogenetic protein receptor II expression in scleroderma
Authors: Wang Yongqing , Kahaleh Bashar
Published: July 2013

Germline mutations in the bone morphogenetic protein type II receptor (BMPRII) gene play an essential role in the pathogenesis of familial pulmonary arterial hypertension (FPAH). In view of the histological similarities between scleroderma (SSc) and FPAH arterial lesion, we examined the expression levels of BMPRII in SSc microvascular endothelial cells (MVEC). Oxidative stress and serum starvation were used to examine apoptotic responses of MVECs. BMPRII expression levels were determined by RT‐PCR and by Western blot. Epigenetic regulation of BMPRII expression was examined by the addition of epigenetic inhibitors to MVECs cultures, by methylation‐specific PCR, and by sequence analysis of DNA methylation pattern of the BMPRII promotor region. SSc‐MVECs were more sensitive to apoptotic signals than were normal‐MVECs. A significant decrease in BMPRII expression levels in SSc‐MVECs was noted, whereas no significant differences in the expression levels of BMPRIA and BMPRIB were observed. Similar reduction in expression levels was noted in SSc skin biopsies. The expression level of BMPRII in SSc‐MVECs was normalized by the addition of 2‐deoxy‐5‐azacytidine and trichostatin A to cell cultures. Extensive CpG sites methylation in the BMPRII promoter region was noted in SSc‐MVECs with no detectable site methylation in control‐MVECs. SSc‐MVECs are more sensitive to apoptotic triggers than are control‐MVECs. The enhanced apoptosis may be related to epigenetic repression of BMPRII expression as apoptosis of control‐MVECs can be augmented by knocking down BMPRII expression. The role of BMPRII underexpression in the pathogenesis of SSc vasculopathy is suggested and should be investigated further.
Parallel speciation or long‐distance dispersal? Lessons from seaweeds (Fucus) in the Baltic Sea
Authors: Pereyra R. T. , Huenchuñir C. , Johansson D. , Forslund H. , Kautsky L. , Jonsson P. R. , Johannesson K.
Published: July 2013

Parallel evolution has been invoked as a forceful mechanism of ecotype and species formation in many animal taxa. However, parallelism may be difficult to separate from recently monophyletically diverged species that are likely to show complex genetic relationships as a result of considerable shared ancestral variation and secondary hybridization in local areas. Thus, species' degrees of reproductive isolation, barriers to dispersal and, in particular, limited capacities for long‐distance dispersal will affect demographical structures underlying mechanisms of divergent evolution. Here, we used nine microsatellite DNA markers to study intra‐ and interspecific genetic diversity of two recently diverged species of brown macroalgae, Fucus radicans (L. Bergström & L. Kautsky) and F. vesiculosus (Linnaeus), in the Baltic Sea. We further performed biophysical modelling to identify likely connectivity patterns influencing the species' genetic structures. For each species, we found intraspecific contrasting patterns of clonality incidence and population structure. In addition, strong genetic differentiation between the two species within each locality supported the existence of two distinct evolutionary lineages (FST = 0.15–0.41). However, overall genetic clustering analyses across both species' populations revealed that all populations from one region (Estonia) were more genetically similar to each other than to their own taxon from the other two regions (Sweden and Finland). Our data support a hypothesis of parallel speciation. Alternatively, Estonia may be the ancestral source of both species, but is presently isolated by oceanographic barriers to dispersal. Thus, a limited gene flow in combination with genetic drift could have shaped the seemingly parallel structure.
Cardiomyopathy of Friedreich Ataxia
Authors: Weidemann Frank , Störk Stefan , Liu Dan , Hu Kai , Herrmann Sebastian , Ertl Georg , Niemann Markus
Published: July 2013

Friedreich's ataxia is a rare hereditary, predominantly neurologically defined multisystem disorder of mitochondrial function. Although the gene defect has been identified, the precise pathophysiology of the deficient mitochondrial protein, frataxin, is unknown. Besides the characteristic features of spinocerebellar ataxia the heart may also be affected, and patients may experience a hypertrophic cardiomyopathy eventually progressing toward heart failure and death. So far, research focused on the neurological aspects and little attention has been paid to better characterize and understand the cardiac involvement in Friedreich's ataxia. For that, a better understanding of longitudinal progression, cardiac complications and long‐term cardiac outcome is warranted. In addition, the clinician should be familiar with the therapeutic option in Friedreich cardiomyopathy. This review discusses important clinical and diagnostic features of the cardiomyopathy in Friedreich's ataxia and potential therapeutic developments.
Gene regulation and epigenetics in Friedreich's ataxia
Authors: Yandim Cihangir , Natisvili Theona , Festenstein Richard
Published: July 2013

This is an exciting time in the study of Friedreich's ataxia. Over the last 10 years much progress has been made in uncovering the mechanisms, whereby the Frataxin gene is silenced by (GAA)n repeat expansions and several of the findings are now ripe for testing in the clinic. The discovery that the Frataxin gene is heterochromatinised and that this can be antagonised in vivo has led to the tantalizing possibility that the disease might be amenable to a more radical therapeutic approach involving epigenetic modifiers. Here, we set out to review progress in the understanding of the fundamental mechanisms whereby genes are regulated at this level and how these findings have been applied to achieve a deeper understanding of the dysregulation that occurs as the primary genetic lesion in Friedreich's ataxia.
Deferiprone for the treatment of Friedreich's ataxia
Authors: Pandolfo Massimo , Hausmann Laura
Published: July 2013

Friedreich's ataxia (FRDA) is a neurological disease related to a deficiency of the protein frataxin involved in iron–sulfur (Fe–S) cluster biogenesis. This leads to an increased cellular iron uptake accumulating in mitochondria, and a subsequently disturbed iron homeostasis. The detailed mechanism of iron regulation of frataxin expression is yet unknown. Deferiprone, an iron chelator that may cross the blood–brain barrier, was shown to shuttle iron between subcellular compartments. It could also transfer iron from iron‐overloaded cells to extracellular apotransferrin and pre‐erythroid cells for heme synthesis. Here, clinical studies on Deferiprone are reviewed in the context of alternative agents such as desferoxamine, with specific regard to its mechanistic and clinical implications.
Increasing frataxin gene expression with histone deacetylase inhibitors as a therapeutic approach for Friedreich's ataxia
Authors: Gottesfeld Joel M. , Rusche James R. , Pandolfo Massimo
Published: July 2013

The genetic defect in Friedreich's ataxia (FRDA) is the expansion of a GAA·TCC triplet in the first intron of the FXN gene, which encodes the mitochondrial protein frataxin. Previous studies have established that the repeats reduce transcription of this essential gene, with a concomitant decrease in frataxin protein in affected individuals. As the repeats do not alter the FXN protein coding sequence, one therapeutic approach would be to increase transcription of pathogenic FXN genes. Histone posttranslational modifications near the expanded repeats are consistent with heterochromatin formation and FXN gene silencing. In an effort to find small molecules that would reactivate this silent gene, histone deacetylase inhibitors were screened for their ability to up‐regulate FXN gene expression in patient cells and members of the pimelic 2‐aminobenzamide family of class I histone deacetylase inhibitors were identified as potent inducers of FXN gene expression and frataxin protein. Importantly, these molecules up‐regulate FXN expression in human neuronal cells derived from patient‐induced pluripotent stem cells and in two mouse models for the disease. Preclinical studies of safety and toxicity have been completed for one such compound and a phase I clinical trial in FRDA patients has been initiated. Furthermore, medicinal chemistry efforts have identified improved compounds with superior pharmacological properties.
Professionals' Perceptions of the Effect of Pornography on Swedish Adolescents
Authors: Mattebo Magdalena , Larsson Margareta , Tydén Tanja , Häggström‐Nordin Elisabet
Published: July 2013

Objective

The aims were to gain a deeper understanding of how personnel, who work with adolescents, reason about the effect of pornography and its spread in the media, and to explore how well prepared they consider themselves to be in addressing sexual health and gender equality.

Design and Sample

An inductive, exploratory, qualitative study with focus group discussions was selected. Seventeen participants with different professions were invited into five heterogeneous groups.

Measures

Data were analyzed according to grounded theory.

Results

Conflicting messages about sexuality became the core category. Participants were of the opinion that pornography conveyed a contradictory message compared with national public health goals, societal laws, and regulations. They believed that young people use pornography as a source of information and stimulation. Furthermore, they thought that pornography contributed to norm‐creating ideals and a demanding sexuality, thus, confirming the traditional gender order. The participants opined that a professional approach was required when addressing sexuality and gender equality issues and requested better training tools and more cultural competence.

Conclusions

Professionals working with adolescents perceived that pornography conveys a conflicting message about sexuality. They expressed a need for adequate tools for improving education on health and sexuality, including gender equality aspects and critical media analysis.
Trade Variety and Productivity in Canada
Authors: Chen Bo
Published: July 2013

This paper combines the effects of import and export variety growth on technological development in a monopolistic competition model with endogenous technology. Using highly disaggregated international trade data at the national and provincial levels from 1988 to 2006, it is found that export variety and import variety account for 10.41% and 1.57% respectively of the variation in Canadian provincial productivity differences, and for 9.92% and 6.95% of within‐province productivity growth. Evaluated at the sample mean, Canadian productivity gained 0.74% as a result of trade variety growth: export variety contributed 0.41% and import variety contributed 0.33%. While the USA is the single most important source of export‐led Canadian productivity growth, its relative importance is much less on the import side. Emerging markets in Asia, especially China, contributed significantly to Canadian productivity growth by increasing import variety for Canadian producers.
“Intentions to Return of Clandestine Migrants: The Perverse Effect of Illegality on Skills”—A Reply to the Note
Authors: Coniglio Nicola D. , De Arcangelis Giuseppe , Serlenga Laura
Published: July 2013

The purpose of this reply is twofold. First, we discuss the major point raised by Stark and Lukasz (Review of Development Economics 17, no. 1 (2013):156–62), i.e. the fact that a framework which explicitly considers asymmetric information is correct and would imply a reversal of our finding. Although, we acknowledge that the mechanism highlighted by the authors is an alternative explanation to return decisions, we argue that the suggested framework is unsuitable in the specific context analyzed in our paper (as well as most real‐world situations). Instead, the assumptions underlying our simple theoretical model are strictly linked to data availability in order to perform a sensible empirical analysis. Second, we present a slightly different version of the model proposed in the original article that overcomes possible inconsistencies on the saving behavior of the migrants. Although all the computations are shown in one of the articles cited in our published paper, we now prefer to show them fully in this issue of the Review. The conclusions of our theoretical model do not change. Hence, we conclude that the empirical evidence of the original article—which is the main contribution of our work—is supported by a robust framework.
Prevention and Treatment of Hemodialysis‐Related Bloodstream Infections
Authors: Camins Bernard C.
Published: July 2013

Despite improvements in the delivery of care, the annual all‐cause mortality rate for end‐stage renal disease (ESRD) patients is still around 220 deaths per 1000 at risk patient‐years. Infection‐related causes are second only to cardiovascular events as a cause for mortality among ESRD patients. Almost two‐thirds of all ESRD patients will require hemodialysis and they are at the highest risk for bloodstream infections. An effective method for reducing bloodstream infections is increasing the use of fistula for dialysis access, but, for a significant number of patients, catheter access is inevitable. Several interventions have been studied that primarily involves the application of antimicrobials at the catheter exit site. Other interventions include the use of antibiotic lock solutions, which have resulted in the development of antibiotic resistance. Novel connecting devices may be of use in the future, but studies are still needed to show their efficacy at preventing catheter‐related bloodstream infections among hemodialysis patients. As insertion sites can be limited in hemodialysis patients, treatment of certain catheter‐related bloodstream infections can be amenable to catheter retention as long as both systemic antibiotic and antibiotic lock therapies are also initiated. Until more data are available, catheter removal followed by systemic therapy is preferred for infections involving Staphylococcus aureus, Pseudomonas species, Enterococcus species, and Candida species.
Equine glaucoma: a histopathologic retrospective study (1999–2012)
Authors: Curto Elizabeth M. , Gemensky‐Metzler Anne J. , Chandler Heather L. , Wilkie David A.
Published: July 2013

Purpose

To characterize and describe the histopathologic findings in equine globes enucleated due to glaucoma.

Methods

Medical records at The Ohio State University from 1999 to 2012 were reviewed retrospectively. Signalment, history, and treatment data were collected, and histologic slides of enucleated globes were examined and lesions recorded. Twenty‐three eyes from 23 horses were eligible for inclusion in this study.

Results

The majority of affected horses were > 15 years of age (65%). The ages ranged from 5 to 35 years (mean = 17.4 years). The left eye was affected in 10 cases (43%) and the right eye in 13 cases (57%). There were 13 mares (56%) and 10 geldings (44%). Quarter Horses (30%), Appaloosas (26%), and Thoroughbreds (22%) were the most common breeds in the study population. The most common histopathologic changes included hypercellularity of the optic nerve (93%), retinal atrophy (89%), corneal vascularization (83%), descemetization of pectinate ligaments (83%), hypercellularity of the anterior corneal stroma (75%), posterior bowing of the iris base (74%), ciliary body atrophy (74%), corneal striae (70%), pars plana elongation (60%), cataract (53%), and collapsed ciliary cleft/trabecular meshwork (52%). Evidence of uveitis (cataract, lymphoplasmacytic infiltration of the uvea, and/or anterior or posterior synechiae) was present in 20/23 eyes (87%).

Conclusions

Equine glaucoma most commonly occurs secondary to uveitis with Appaloosas and older horses predisposed. Histologic changes are comparable to prior reports of chronic glaucoma; notable findings not previously described in the horse were posterior bowing of the iris base and relative sparing of the superior retina from atrophy associated with elevatedIOP.
Detailed Study of Fluid Flow and Heat Transfer in the Abrasive Grinding Contact Using Computational Fluid Dynamics Methods
Authors: Mihić Stefan D. , Cioc Sorin , Marinescu Ioan D. , Weismiller Michael C.
Published: July 2013

This paper introduces a set of research oriented computational fluid dynamics (CFD) 3D models used to simulate the fluid flow and heat transfer in a grinding process. The most important features of these models are described and some representative simulation results are presented, along with comparisons to published experimental data. Distributions of temperatures, pressures, velocities, and liquid volume fractions in and around the grinding region are obtained in great detail. Such results are essential in studying the influence of the fluid on the grinding process, as well as in determining the best fluid composition and supply parameters for a given application. The simulation results agree well with experimental global flow rates, temperature, and pressure values, showing the feasibility of CFD simulations in grinding applications.
New Approach of Gas–Liquid Computational Fluid Dynamics Simulations for the Study of Minimum Quantity Cooling With Airblast Plain-Jet Injectors
Authors: Diakodimitris Christophe , Iskandar Youssef R. , Hendrick Patrick , Slangen Pierre
Published: July 2013

Due to the complexity of multiphase flows, they are often studied with numerical simulations. These simulations must be validated with experimental results. This paper introduces a new approach to initialize the continuous phase of gas–liquid flows generated by airblast nozzles for microlubrication applications with a recently modified commercial computational fluid dynamics (CFD) code FINE™/Open. Microlubrication is a technology used in metal machining where the coolant flow rate is lower than with conventional flood cooling. In this paper, single-phase gas and two-phase liquid–gas flows are studied. The continuous phase is simulated using Reynolds-averaged Navier–Stokes (RANS) equations coupled with a k–ε turbulence model and the dispersed phase is simulated using a Lagrangian method. To validate these simulations, particle image velocimetry (PIV) and particle dynamics analysis (PDA) measurements have been performed. This study illustrates the possibility of performing complex two-phase simulations with the help of single-phase studies to initialize the continuous phase of the flow (i.e., the gas). The single-phase flow also helps in estimating the magnitudes of the droplet velocities.
Combined Effects of Stress and Temperature During Ductile Mode Microlaser Assisted Machining Process
Authors: Virkar Saurabh R. , Patten John A.
Published: July 2013

This work emphasizes the stress and temperature effects during the microlaser assisted machining (μ-LAM) process using three approaches: normalized cutting force approach, yield strength as a function of temperature approach and yield strength as a function of pressure and temperature approach. μ-LAM is a ductile mode material removal process developed for precision machining of nominally brittle materials augmented with thermal softening (provided by laser heating). In the μ-LAM process, a laser is used for heating the workpiece where the laser passes through the optically transparent diamond tool and emerges at the tool-workpiece interface, in the chip formation zone. This work is mainly focused on ductile mode machining of Silicon Carbide. 2D Numerical simulations were conducted using the software AdvantEdge (developed by Third Wave Systems) to predict the cutting forces and pressures that occur during the μ-LAM process. A thermal softening curve was developed based on various references to incorporate this behavior in the simulations. A thermal boundary condition was defined on the workpiece top surface to mimic the laser heating effect. The thermal boundary temperatures were varied from room temperature (20 °C) to 2700 °C, close to the melting point (2830 °C) of silicon carbide (SiC). The decrease in yield strength is also predicted from the thermal softening curve. The first approach (normalized cutting force) is based on the cutting forces obtained from the simulation output. It is an approximate way to represent the relative dominance of stress and temperature. The second approach determines the temperature (percentage) contribution using the yield strength at room temperature and at higher temperatures. The third approach (yield strength) is based on calculated yield using the Drucker–Prager pressure sensitive yield criterion. The stress values for the calculation of yield are obtained from the simulation output. The results from all of the approaches show a similar effect of stress and temperature on the workpiece at the simulated temperature points. The cutting pressures also decrease rapidly above the thermal cutoff point.
A New Crack Healing Kinetic Model and Application of Crack Healing Diagram
Authors: Kan Y. , Liu H. , Zhang S. H. , Zhang L. W. , Cheng M.
Published: July 2013

An internal crack is a common defect which can lead to failure of the material. There are few published studies which can quantitatively predict healed fractions under given conditions such as temperature, pressure and healing time. In the current study, a new crack healing kinetic model is developed to predict the healed crack fraction under any given temperature, pressure and healing time. In contrast to previous models, this new model describes the crack surface topography as a series of semi spherical pores, and proposes a new diffusion healing mechanism involving grain growth. Plastic deformation, power law creep and diffusion controlled creep mechanism are considered in this model. A crack healing diagram for 34MnV steel is constructed with axes of healed fraction and temperature or pressure. The predictions from the new model compare well with experimental results. The results of the model indicate that the diffusion controlled creep mechanism contributes little at high temperatures because of grain growth. The critical healing time and pressure can be determined by using the crack healing diagram.
Design and Analysis of Volute Casing: A Review
Authors: Baloni Beena D. , Channiwala S. A.
Published: July 2013

Future development of more efficient volute casing depends on improving understanding of the design and flow analysis of the volute casing. This paper reviews different aspects of design and flow behavior inside the volute casing. It describes advantages and disadvantages of the different designs, the relation between flow and geometry, the impact on the impeller and the flow behavior inside the volute. The main purpose is to provide an insight into the flow structure that can be used later to improve the performance or remediate some problems. The use of CFD is also discussed for the flow domain.
Evaporative Cooling of Gas Turbine Engines
Authors: Chaker Mustapha , Meher-Homji Cyrus B.
Published: July 2013

There are numerous gas turbine applications in power generation and mechanical drive service where power drop during the periods of high ambient temperature has a very detrimental effect on the production of power or process throughput. Several geographical locations experience very high temperatures with low coincident relative humidities. In such cases media evaporative cooling can be effectively applied as a low cost power augmentation technique. Several misconceptions exist regarding their applicability of evaporative cooling the most prevalent being that they can only be applied in extremely dry regions. This paper provides a detailed treatment of media evaporative cooling, discussing aspects that would be of value to an end user including selection of climatic design points, constructional features of evaporative coolers, thermodynamic aspects of its effect on gas turbines and approaches to improve reliability. It is hoped that this paper will be of value to plant designers, engineering companies and operating companies that are considering the use of media evaporative cooling.
Study on Practical Application of Turboprop Engine Condition Monitoring and Fault Diagnostic System Using Fuzzy-Neuro Algorithms
Authors: Kong Changduk , Lim Semyeong , Kim Keonwoo
Published: July 2013

Recently, the expert engine diagnostic systems using the artificial intelligent methods such as Neural Networks, Fuzzy Logic and Genetic Algorithms have been studied to improve the model based engine diagnostic methods. Among them the Neural Networks is mostly used to engine fault diagnostic system due to its good learning performance, but it has a drawback due to low accuracy and long learning time to build learning data base if only use of the Neural Networks. In addition, it has a very complex structure due to finding effectively faults of single type faults and multiple type faults of gas path components.

This work builds inversely a base performance model of a turboprop engine to be used for a high altitude operation UAV using measuring performance data, and proposes a fault diagnostic system using the base performance model and artificial intelligent methods such as Fuzzy and Neural Networks. Each real engine performance model, which is named as the base performance model that can simulate a new engine performance, is inversely made using its performance test data. Therefore the condition monitoring of each engine can be more precisely carried out through comparison with measuring performance data.

The proposed diagnostic system identifies firstly the faulted components using Fuzzy Logic, and then quantifies faults of the identified components using Neural Networks leaned by fault learning data base obtained from the developed base performance model. In leaning the measuring performance data of the faulted components, the FFBP(Feed Forward Back Propagation) is used. In order to user’s friendly purpose, the proposed diagnostic program is coded by the GUI type using MATLAB.

The proposed program is verified by application of several case studies having the arbitrary implanted engine component faults as well as real engine performance data.
Rotating Instability in a Centrifugal Blower With Shrouded Impeller
Authors: Kowshik C. K. P. , Tsugita Daisuke , Takeyama Yusuke , Ohta Yutaka
Published: July 2013

Rotating instability in various types of fans, compressors, and pumps is considered as one of the symptoms of unsteady phenomena such as rotating stall or surge, and it is observed before a rotating stall as an amplitude increase in the power spectra of velocity fluctuation and/or radiated noise. In this paper, the cause of rotating instability in a centrifugal blower with a shrouded impeller is investigated through both experiments and numerical simulations. Experimental results show that the rotating instability may be attributed to unsteady vortices rotating along the impeller periphery and that a discrete noise component induced by the rotating instability is mainly caused by the interaction between unsteady vortices and the impeller discharge flow. A significant amplitude increase within a frequency band at almost half the blade passing frequency is found to be caused by an irregular change in the vortex rotating speed as well as by an irregular time interval in the train of generated vortices. In the numerical study, the structure and circumferential characteristics of the rotating vortices are investigated by a visualization technique using Q-definition. Circumferential characteristics of the rotating vortices may be largely influenced by the steady characteristics of the impeller discharge flow field, which are determined by the geometric configuration of the impeller and the scroll casing.
An Expanded Cost of Electricity Model for Highly Flexible Power Plants
Authors: Gülen S. Can , Mazumder Indrajit
Published: July 2013

Cost of electricity (COE) is the most widely used metric to quantify the cost-performance trade-off involved in comparative analysis of competing electric power generation technologies. Unfortunately, the currently accepted formulation of COE is only applicable to comparisons of power plant options with the same annual electric generation (kilowatt-hours) and same technology as defined by reliability, availability and operability. Such a formulation does not introduce a big error into the COE analysis when the objective is simply to compare two or more baseloaded power plants of the same technology (e.g., natural gas fired gas turbine simple or combined cycle, coal fired conventional boiler steam turbine, etc.) and the same (or nearly the same) capacity. However, comparing even the same technology class power plants, especially highly flexible advanced gas turbine combined cycle units with cyclic duties, comprising a high number of daily starts and stops in addition to emissions-compliant low-load operation to accommodate the intermittent and uncertain load regimes of renewable power generation (mainly wind and solar) requires a significant overhaul of the basic COE formula.

This paper develops an expanded COE formulation by incorporating crucial power plant operability and maintainability characteristics such as reliability, unrecoverable degradation, and maintenance factors as well as emissions into the mix. The core impact of duty cycle on the plant performance is handled via effective output and efficiency utilizing basic performance correction curves. The impact of plant start and load ramps on the effective performance parameters is included. Differences in reliability and total annual energy generation are handled via energy and capacity replacement terms. The resulting expanded formula, while rigorous in development and content, is still simple enough for most feasibility study type of applications. Sample calculations clearly reveal that inclusion (or omission) of one or more of these factors in the COE evaluation, however, can dramatically swing the answer from one extreme to the other in some cases.
Investigation of the Potential of Gas Turbines for Vehicular Applications
Authors: Cunha Henrique E. , Kyprianidis Konstantinos G.
Published: July 2013

Nowadays, the reduction of fuel consumption and pollutant emissions has become a top priority for society and economy. In the past decades, some of the environmental advantages of the gas turbine (such as inherently low CO and unburned HC) have led some car manufacturers to evaluate the potential of this type of engine as prime mover. This paper suggests a strategy to assess the fuel consumption of gas turbines applied in road vehicles. Based on a quasistatic approach, a model was created that can simulate road vehicles powered by gas turbines, and thereafter a comparison was established with reciprocating engines. Within this study, material and turbomachinery technology developments that have taken place in micro gas turbines since the 1960’s have been considered. A 30% efficiency improvement target has been identified with respect to making the gas turbine fuel competitive to a diesel engine powering an SUV. It is the authors’ view that several technologies that could mature sufficiently within the next 10–15 years exist, such as uncooled ceramic turbines. Such technologies could help bridge the fuel efficiency gap in micro gas turbines and make them commercially competitive in the future for low-emissions vehicular applications. Furthermore, the system developed also allows the simulation of hybrid configurations using gas turbines as range extenders, a solution that some car manufacturers consider to be the most promising in the coming years.
Performance Comparison on Cross-Flow and Counter-Flow Planar Solid Oxide Fuel Cell
Authors: Zhang Huisheng , Zhang Wenshu , Lu Zhenhua , Weng Shilie
Published: July 2013

Solid oxide fuel cell (SOFC) is a complicated system with heat and mass transfer as well as electrochemical reactions. The flow configuration has great impact on the system performance. Based on the established one dimensional direct internal reforming SOFC mathematical model, with the consideration of the flow, thermal and electrical characteristic, this paper developed the two dimensional mathematical model for both counter-flow and cross-flow types. Plus, the comparison and analysis of the steady distribution are performed. The results reveal that on the geometry parameters and inlet conditions, the outlet temperatures of counter-flow SOFC are lower than that of cross-flow. However, the average temperature of PEN plate is higher than cross-flow, and both the operating voltage and electric efficiency are also higher than that of cross-flow. This will be beneficial for the structure design of SOFC.
Smart Polygeneration Grid: A New Experimental Facility
Authors: Ferrari Mario L. , Pascenti Matteo , Traverso Alberto , Rivarolo Massimo
Published: July 2013

This paper presents the development of a new experimental facility for analysis and optimization activities on smart polygeneration grids. The test rig is being designed and built in the framework of the European project “Energy-Hub for residential and commercial districts and transport” (E-HUB), which targets optimal energy management of residential and commercial districts.

The experimental rig, named “Energy aNd Efficiency Research Demonstration District” (E-NERDD), is located inside the University campus in Savona, and is based on four different prime movers able to produce both electrical and thermal energy: a 100 kWe micro gas turbine, a 20 kWe internal combustion engine, a 3 kWe Stirling engine, and a 450 kWe fuel cell/gas turbine hybrid system emulator based on the coupling of a micro gas turbine with a modular vessel. While the electrical side is based on the connection with the campus grid (further developments are planned for a local electrical grid including storage units), thermal energy is managed through a dual ring-based water distribution system. The facility is also equipped with thermal storage tanks and fan cooler units to study and optimize different thermal management algorithms generating different thermal load demands. The facility also includes an absorption chiller for cold water generation. As a result, trigeneration operation is possible in a physically simulated urban district. Moreover, the rig is equipped with six photovoltaic panels (significant for the electrical aspects) and 10 kWp of thermal solar panels to be integrated in the grid.

Further technologies to be considered for the E-NERDD are power plants based on other renewable resource (e.g. with biomass fuel). These systems are planned to be analyzed through real plants (remote connection with the field) or through virtual models based on real-time dynamic approaches.

Experimental tests related to the performance of the micro gas turbine are reported and discussed in this paper. The focus here is on machine correction curves essential to evaluate factors for quantifying ambient temperature influence on machine performance. This analysis is essential for setting the thermal distribution grid and for future optimization tests.