bluuebunny/crossref_metadata_2025 huggingface dataset:
Polarized release of hepatic microRNAs into bile and serum in response to cellular injury and impaired liver function
Authors: Verhoeven Cornelia J. , Farid Waqar R. R. , Roest Henk P. , Ramakrishnaiah Vedashree , de Ruiter Petra E. , de Jonge Jeroen , Kwekkeboom Jaap , Metselaar Herold J. , Tilanus Hugo W. , Kazemier Geert , Ijzermans Jan N. M. , van der Laan Luc J. W.
Published: September 2015

Background & Aims

Extracellular microRNAs (miRNAs) in serum and bile are currently under intense investigation for biomarker purposes in liver disease. However, the directions and pathways by which miRNAs are released from hepatic cells remains largely unknown. Here, we investigated the release of hepatocyte and cholangiocyte‐derived miRNAs (HDmiRs and CDmiRs) into blood and bile during various (patho)physiological hepatic conditions.

Methods

MiRNA release was analysed using longitudinally collected tissue and paired bile and serum samples (n = 124) that were obtained from liver transplant recipients during follow‐up.

Results

Cell‐type specificity of HDmiRs and CDmiRs was confirmed in liver and common bile duct biopsies (P < 0.001). Analysis of paired bile and serum samples showed up to 20‐times higher miRNA‐levels in bile compared to serum (P < 0.0001). Fractionation of bile showed the majority of miRNAs being present in the unpelletable supernatant, where protein conjunctions protect miRNAs against degradation (P < 0.0001). During episodes of liver injury and histologically proven rejection in liver transplant recipients, relative HDmiR‐levels in bile decreased while its levels in serum increased (P ≤ 0.015). Simultaneously, relative CDmiR‐levels in bile significantly increased, while their levels in serum decreased. Related to liver excretory function, a strong positive correlation was observed between HDmiR‐122 levels and bilirubin excretion into bile (R = 0.694, P < 0.0001), whereas CDmiRs showed an inverse correlation (P < 0.05).

Conclusion

During impaired excretory function and injury, the liver shows polarized release of extracellular HDmiRs and CDmiRs. This sheds new light on the biology of hepatic miRNA release which is relevant for the interpretation of hepatic miRNAs as biomarkers.
Comparison of user‐friendliness and treatment cost of Loceryl® vs. Ciclopoli® – a patient's perspective
Authors: Schaller M. , Braunsdorf C. , Mailänder‐Sanchez D. , Jäckel A. , Müller J. , Borelli C.
Published: September 2015

Topical monotherapy is a valid therapeutic approach in onychomycosis. Due to its lengthy course and its non‐reimbursed product status, cost and compliance are important issues and non‐pharmacological properties such as over‐the‐counter price and ease of use should be considered when deciding which product to recommend. We investigated surrogate parameters for patient‐friendliness and treatment cost in Germany in a questionnaire‐based prospective, comparative, intra‐individual, open‐label trial of the two common topical antifungal nail lacquers Loceryl® (amorolfine 5%) and Ciclopoli® (ciclopirox 8%) in eight patients with clinically diagnosed onychomycosis. The 2.5 ml bottle of Loceryl® covered a treatment period of 308 days, resulting in treatment costs of €0.10 per day in comparison to the 3.3 ml bottle of Ciclopoli®, covering 127 days at €0.21 per day, given once‐daily application for Ciclopoli® and once‐weekly application for Loceryl® in accordance with regulatory approval. Six out of eight patients favoured the Loceryl® treatment regimen. Furthermore, four out of eight patients found Loceryl® easier to apply, whereas three preferred Ciclopoli®. In total, seven out of eight stated a clear preference for Loceryl® over Ciclopoli®. Loceryl® therapy is less expensive and less time‐consuming. The therapeutic period that can be covered is longer and more patients stated a clear preference for Loceryl® in comparison to Ciclopoli®. The differences are statistically significant, underlining probable clinical relevance.
High‐throughput sequencing reveals key genes and immune homeostatic pathways activated in myeloid dendritic cells by Porphyromonas gingivalis 381 and its fimbrial mutants
Authors: Arjunan P. , El‐Awady A. , Dannebaum R.O. , Kunde‐Ramamoorthy G. , Cutler C.W.
Published: September 2015

The human microbiome consists of highly diverse microbial communities that colonize our skin and mucosal surfaces, aiding in maintenance of immune homeostasis. The keystone pathogen Porphyromonas gingivalis induces a dysbiosis and disrupts immune homeostasis through as yet unclear mechanisms. The fimbrial adhesins of P. gingivalis facilitate biofilm formation, invasion of and dissemination by blood dendritic cells; hence, fimbriae may be key factors in disruption of immune homeostasis. In this study we employed RNA‐seqencing transcriptome profiling to identify differentially expressed genes (DEGs) in human monocyte‐derived dendritic cells (MoDCs) in response to in vitro infection/exposure by Pg381 or its isogenic mutant strains that solely express minor‐Mfa1 fimbriae (DPG3), major‐FimA fimbriae (MFI) or are deficient in both fimbriae (MFB) relative to uninfected control. Our results yielded a total of 479 DEGs that were at least two‐fold upregulated and downregulated in MoDCs significantly (P ≤ 0.05) by all four strains and certain DEGs that were strain‐specific. Interestingly, the gene ontology biological and functional analysis shows that the upregulated genes in DPG3‐induced MoDCs were more significant than other strains and associated with inflammation, immune response, anti‐apoptosis, cell proliferation, and other homeostatic functions. Both transcriptome and quantitative polymerase chain reaction results show that DPG3, which solely expresses Mfa1, increased ZNF366, CD209, LOX1, IDO1, IL‐10, CCL2, SOCS3, STAT3 and FOXO1 gene expression. In conclusion, we have identified key DC‐mediated immune homeostatic pathways that could contribute to dysbiosis in periodontal infection with P. gingivalis.
Overexpression of GA20‐OXIDASE1 impacts plant height, biomass allocation and saccharification efficiency in maize
Authors: Voorend Wannes , Nelissen Hilde , Vanholme Ruben , De Vliegher Alex , Van Breusegem Frank , Boerjan Wout , Roldán‐Ruiz Isabel , Muylle Hilde , Inzé Dirk
Published: September 2015

Increased biomass yield and quality are of great importance for the improvement of feedstock for the biorefinery. For the production of bioethanol, both stem biomass yield and the conversion efficiency of the polysaccharides in the cell wall to fermentable sugars are of relevance. Increasing the endogenous levels of gibberellic acid (GA) by ectopic expression of GA20‐OXIDASE1 (GA20‐OX1), the rate‐limiting step in GA biosynthesis, is known to affect cell division and cell expansion, resulting in larger plants and organs in several plant species. In this study, we examined biomass yield and quality traits of maize plants overexpressing GA20‐OX1 (GA20‐OX1). GA20‐OX1 plants accumulated more vegetative biomass than control plants in greenhouse experiments, but not consistently over two years of field trials. The stems of these plants were longer but also more slender. Investigation of GA20‐OX1 biomass quality using biochemical analyses showed the presence of more cellulose, lignin and cell wall residue. Cell wall analysis as well as expression analysis of lignin biosynthetic genes in developing stems revealed that cellulose and lignin were deposited earlier in development. Pretreatment of GA20‐OX1 biomass with NaOH resulted in a higher saccharification efficiency per unit of dry weight, in agreement with the higher cellulose content. On the other hand, the cellulose‐to‐glucose conversion was slower upon HCl or hot‐water pretreatment, presumably due to the higher lignin content. This study showed that biomass yield and quality traits can be interconnected, which is important for the development of future breeding strategies to improve lignocellulosic feedstock for bioethanol production.
Plant‐made oral vaccines against human infectious diseases—Are we there yet?
Authors: Chan Hui‐Ting , Daniell Henry
Published: September 2015

Although the plant‐made vaccine field started three decades ago with the promise of developing low‐cost vaccines to prevent infectious disease outbreaks and epidemics around the globe, this goal has not yet been achieved. Plants offer several major advantages in vaccine generation, including low‐cost production by eliminating expensive fermentation and purification systems, sterile delivery and cold storage/transportation. Most importantly, oral vaccination using plant‐made antigens confers both mucosal (IgA) and systemic (IgG) immunity. Studies in the past 5 years have made significant progress in expressing vaccine antigens in edible leaves (especially lettuce), processing leaves or seeds through lyophilization and achieving antigen stability and efficacy after prolonged storage at ambient temperatures. Bioencapsulation of antigens in plant cells protects them from the digestive system; the fusion of antigens to transmucosal carriers enhances efficiency of their delivery to the immune system and facilitates successful development of plant vaccines as oral boosters. However, the lack of oral priming approaches diminishes these advantages because purified antigens, cold storage/transportation and limited shelf life are still major challenges for priming with adjuvants and for antigen delivery by injection. Yet another challenge is the risk of inducing tolerance without priming the host immune system. Therefore, mechanistic aspects of these two opposing processes (antibody production or suppression) are discussed in this review. In addition, we summarize recent progress made in oral delivery of vaccine antigens expressed in plant cells via the chloroplast or nuclear genomes and potential challenges in achieving immunity against infectious diseases using cold‐chain‐free vaccine delivery approaches.
Scanning Electron Microscopic Hair Shaft Analysis in Ectodermal Dysplasia Syndromes
Authors: Hirano‐Ali Stefanie A. , Reed Ashley M. , Rowan Brandon J. , Sorrells Timothy , Williams Judith V. , Pariser David M. , Hood Antoinette F. , Salkey Kimberly
Published: September 2015

Objectives

The objective of the current study was to catalog hair shaft abnormalities in individuals with ectodermal dysplasia (ED) syndromes using scanning electron microscopy (SEM) and to compare the findings with those in unaffected controls. This is the second of a two‐part study, the first of which used light microscopy as the modality and was previously published.

Methods

Scanning electron microscopy was performed in a blinded manner on hair shafts from 65 subjects with seven types of ED syndromes and 41 unaffected control subjects. Assessment was performed along the length of the shaft and in cross section.

Setting

Hair donations were collected at the 28th Annual National Family Conference held by the National Foundation for Ectodermal Dysplasia. Control subjects were recruited from a private dermatology practice and an academic children's hospital outpatient dermatology clinic.

Results

SEM identified various pathologic hair shaft abnormalities in each type of ED and in control patients. When hairs with all types of ED were grouped together and compared with those of control patients, the difference in the presence of small diameter and shallow and deep grooves was statistically significant (p < 0.05). When the EDs were separated according to subtype, statistically significant findings were also seen.

Conclusion

SEM is a possible adjuvant tool in the diagnosis of ED syndromes. There are significant differences, with high specificity, between the hairs of individuals with ED and those of control subjects and between subtypes.
Adolescents' understandings of infidelity
Authors: NORONA JERIKA C. , KHADDOUMA ALEXANDER , WELSH DEBORAH P. , SAMAWI HANNAH
Published: September 2015

This study explored younger adolescents' (aged 14–17 years;N= 204; 50% girls) understandings of infidelity and whether these understandings differed for girls and boys. Analyses revealed that younger adolescents' understandings of infidelity included an array of physical, affective, cognitive, and verbal behaviors with an extradyadic partner. No gender differences were found. In addition, younger adolescents' understandings of infidelity were compared to older adolescents' (aged 17–21 years;N= 214; 50% girls) understandings. Results showed that younger adolescents' salient understandings of infidelity more often includedlight, affectionate behaviors such as hugging and kissing an extradyadic partner, whereas older adolescents' salient understandings more often includedheavyphysical behaviors, including sexual intercourse and oral sex. Gender comparisons with older adolescents revealed that boys' salient understandings of infidelity included higher numbers ofheavyphysical behaviors, whereas girls' salient understandings included higher numbers of light, affectionate behaviors. Results demonstrate that infidelity is a complex and multifaceted construct for adolescent girls and boys and suggest that developmental researchers should examine understandings of infidelity beyond sexual extradyadic experiences. Implications for adolescent development and psychosocial health are discussed.
A prototype analysis of vengeance
Authors: ELSHOUT MAARTJE , NELISSEN ROB M. A. , VAN BEEST ILJA
Published: September 2015

The authors examined the concept of vengeance from a prototype perspective. In 6 studies, the prototype structure of vengeance was mapped. Sixty‐nine features of vengeance were identified (Study 1), and rated on centrality (Study 2). Further studies confirmed the prototype structure. Compared to peripheral features (e.g., religion, shame, and self‐esteem), central features (e.g., humiliation, honor, and power) were more often recalled and recognized in memory tests (Study 3), classified as vengeance more often and faster (Study 4), and rated higher in participants' autobiographical vengeance recalls (Studies 5 and 6). Lay conceptions of vengeance included the view that vengeance is planned, personal, and aggressive, and involves intense feelings of anger, humiliation, envy, and vindictive feelings, as well as negative thoughts.
Partner's understanding of affective–cognitive meta‐bases predicts relationship quality
Authors: TAN KENNETH , SEE YA HUI MICHELLE , AGNEW CHRISTOPHER R.
Published: September 2015

Knowledge that partners have about each other's attitudes are consequential for relationship quality. This article extends prior research and examines whether knowledge regarding a partner's meta‐attitudinal bases, or subjective perceptions of how one's attitudes are driven, can influence relationship quality. Given how meta‐bases are reflective of information‐processing goals, we hypothesized that partner understanding of meta‐attitudinal bases would positively predict relationship quality. Self and partner ratings of how relationally relevant attitudes were driven, as well as perceptions of relationship quality, were assessed. Results revealed that a partner's knowledge of one's meta‐bases positively predicts one's own reported relationship quality. Results remained significant when controlling for relationship duration and meta‐bases similarity. Implications of meta‐bases understanding for close relationship functioning are discussed.
The effects of prestarvation diet on starvation tolerance of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae)
Authors: Ghazy Noureldin A. , Osakabe Masahiro , Aboshi Takako , Mori Naoki , Amano Hiroshi
Published: September 2015

Understanding the factors affecting stress tolerance in phytoseiid mites is critical for their integration into biological control programs. In the present study, the effects of diet (varying in prey species, physiological status and phenotype) are examined on the future starvation tolerance of the predatory mite Neoseiulus californicus McGregor (Acari: Phytoseiidae). The predators are fed from egg to adulthood on diapausing or nondiapausing Tetranychus urticae, Tetranychus kanzawai (wild and albino strains) or the nondiapausing species Panonychus citri (wild and albino strains). Thereafter, 3‐day‐old mated adult females are held without food at 25 ± 1 °C and a relative humidity of 98 ± 2%. The survival of these starved females is observed daily until all females have died. The survival curves and mean survival times of N. californicus are found to vary among prey types and are significantly longer when the predator is fed with diapausing prey. This enhanced survival is consistent with high concentrations of glycogen and triacylglyceride in the body of the predator at the onset of starvation. The predators fed nondiapausing prey have shorter survival times, and the glycogen and triacylglyceride contents in their bodies are low or undetectable. The protein contents of the predator's body are similar after consuming different prey types, except for a high concentration when fed the albino strain of P. citri. Protein content is unlikely to play a direct role in starvation tolerance, although it may affect the response to varying glycogen and triacylglyceride levels. These findings indicate that nutritional value of prey has a strong impact on the starvation tolerance of N. californicus.
Covenant of Mayors: Reasons for Being an Environmentally and Energy Friendly Municipality
Authors: Pablo‐Romero María del P. , Sánchez‐Braza Antonio , Manuel González‐Limón José
Published: September 2015

The Covenant of Mayors (CM) is the mainstream European movement involving local authorities who voluntarily commit to increase energy efficiency and the use of renewable energy sources within their territories with the aim of reducing CO2 emissions and meet the European Union objectives by 2020. One country that has a greater number of signatories of this agreement is Spain. This article analyzes which factors influence the decision of Spanish local authorities to join the ever‐growing movement. An empirical model is formulated to describe the behavior of Spanish local governments, this being a binary choice model which is a function of various political, economic, and technical factors. Among the prominent factors that influence this decision are population, availability of renewable energy, fiscal and environmental stress, citizens’ political preference, the contagion effect of neighboring municipalities, the existence of covenant coordinators, and finally, economic motivations.
Persistently Biased: The Devil Shift in Water Privatization in Jakarta
Authors: Leong Ching
Published: September 2015

This article operationalizes an underinvestigated element of the Advocacy Coalition Framework—the “devil shift”—on the controversial issue of water privatization. In doing so, it offers a methodological premise for investigating intractable opposition to policies that are politically salient and high in technical content. It uses the Q methodology on the case of Jakarta, Indonesia to uncover seven discourse coalitions within the anti‐privatization groups. They confirm two key hypotheses within the devil shift, namely the underestimation of a coalition's resources compared with their opponents and the exaggeration of opponents’ unreasonableness. Intriguingly, it finds that the “devil” is constructed in three different ways by this coalition—the profiteer, the Goliath, and the ineffectual governor. The narrative strength of the combination of these beliefs answers an apparent paradox in the devil shift viz that of rational actors persisting in unreasonable beliefs concerning their opponents. It also offers some specific solutions on how to deal with public hostility in water privatization in Jakarta.
Disseminated mucormycosis with myocardial involvement in a renal transplant recipient
Authors: Nam Y. , Jung J. , Park S.S. , Kim S.J. , Shin S.J. , Choi J.H. , Kim M. , Yoon H.E.
Published: September 2015

We report the case of a renal transplant recipient with pulmonary and splenic mucormycosis whose demise was accelerated by a myocardial abscess. Once pulmonary and splenic mucormycosis was diagnosed, liposomal amphotericin B was started and immunosuppressant treatments were discontinued. The pulmonary cavities regressed during treatment, but new myocardial and peri‐allograft abscesses developed. The myocardial abscess diffusely infiltrated the left ventricular wall and was associated with akinesia, which led to sudden cardiac arrest. This case demonstrates a rare manifestation of mucormycosis and highlights the fatality and invasiveness of this infection.
Chikungunya infection in a human immunodeficiency virus‐infected kidney transplant recipient returning to Italy from the Dominican Republic
Authors: Dalla Gasperina D. , Balsamo M.L. , Garavaglia S.D. , Rovida F. , Baldanti F. , Grossi P.A.
Published: September 2015

Since December 2013, chikungunya virus (CHIKV) spread in many countries of the Western Hemisphere, and during the last year some cases of infected European travelers, coming back from the Caribbean, have been reported. The risk of acquiring severe travel‐related illness is higher in immunocompromised subjects, such as patients with human immunodeficiency virus (HIV) infection or solid organ transplant recipients. We reported the first case, to our knowledge, of CHIKV infection in an HIV‐infected kidney transplant recipient.
Probable and possible transfusion‐transmitted dengue associated with NS1 antigen–negative but RNA confirmed‐positive red blood cells
Authors: Matos Desiree , Tomashek Kay M. , Perez‐Padilla Janice , Muñoz‐Jordán Jorge , Hunsperger Elizabeth , Horiuchi Kalanthe , Noyd David , Winton Colleen , Foster Gregory , Lanteri Marion , Linnen Jeffrey M. , Stramer Susan L.
Published: September 2015

BACKGROUND

In the absence of active blood donation screening, dengue viruses (DENV) have been implicated in only a limited number of transfusion transmissions worldwide. This study attempted to identify if blood from donors testing negative by an NS1‐antigen (Ag) enzyme‐linked immunosorbent assay (ELISA) but confirmed positive for DENV RNA caused DENV‐related disease in recipients during the epidemic years of 2010 to 2012 in Puerto Rico.

STUDY DESIGN AND METHODS

Donation aliquots testing negative by an investigational NS1‐Ag ELISA were stored frozen and retested retrospectively using a research transcription‐mediated amplification assay (TMA) detecting DENV RNA. All RNA‐reactive donations were subject to confirmatory RNA and antibody testing. Recipient tracing was conducted for all components manufactured from TMA‐reactive components. Medical chart review, recipient interview, and follow‐up sampling occurred for 42 recipients transfused with TMA‐reactive components.

RESULTS

Six of 42 recipients developed new‐onset fever in the 2 weeks posttransfusion; three (50%) received RNA confirmed‐positive, NS1‐Ag–negative red blood cell (RBC) units. One recipient of a high‐titer unit (7 × 107 DENV‐4 RNA copies/mL) developed severe dengue, and a second recipient had only fever recorded but had a negative sepsis work‐up. New fever attributable to DENV infection in a third recipient was confounded by fever potentially attributable to posttransfusion sepsis.

CONCLUSIONS

In our retrospective study, NS1‐Ag detected 20% of all RNA confirmed‐positive donations demonstrating limitations of NS1‐Ag ELISA for blood donation screening. We identified one recipient with a clinical syndrome compatible with severe dengue who had received an NS1‐Ag–negative but RNA confirmed‐positive RBC unit. This investigation illustrates the difficulty in confirming transfusion transmission in dengue‐endemic areas among severely ill transfusion recipients.
Cusp forms on the exceptional group of type
Authors: Kim Henry H. , Yamauchi Takuya
Published: September 2015

Let $\mathbf{G}$ be the connected reductive group of type $E_{7,3}$ over $\mathbb{Q}$ and $\mathfrak{T}$ be the corresponding symmetric domain in $\mathbb{C}^{27}$. Let ${\rm\Gamma}=\mathbf{G}(\mathbb{Z})$ be the arithmetic subgroup defined by Baily. In this paper, for any positive integer $k\geqslant 10$, we will construct a (non-zero) holomorphic cusp form on $\mathfrak{T}$ of weight $2k$ with respect to ${\rm\Gamma}$ from a Hecke cusp form in $S_{2k-8}(\text{SL}_{2}(\mathbb{Z}))$. We follow Ikeda’s idea of using Siegel’s Eisenstein series, their Fourier–Jacobi expansions, and the compatible family of Eisenstein series.
Quantum groups via cyclic quiver varieties I
Authors: Qin Fan
Published: September 2015

We construct the quantized enveloping algebra of any simple Lie algebra of type$\mathbb{A}\mathbb{D}\mathbb{E}$as the quotient of a Grothendieck ring arising from certain cyclic quiver varieties. In particular, the dual canonical basis of a one-half quantum group with respect to Lusztig’s bilinear form is contained in the natural basis of the Grothendieck ring up to rescaling. This paper expands the categorification established by Hernandez and Leclerc to the whole quantum groups. It can be viewed as a geometric counterpart of Bridgeland’s recent work for type$\mathbb{A}\mathbb{D}\mathbb{E}$.
Arithmetic of positive characteristic -series values in Tate algebras
Authors: Anglès B. , Pellarin F. , Tavares Ribeiro F. , Demeslay F.
Published: September 2015

The second author has recently introduced a new class of$L$-series in the arithmetic theory of function fields over finite fields. We show that the values at one of these$L$-series encode arithmetic information of a generalization of Drinfeld modules defined over Tate algebras that we introduce (the coefficients can be chosen in a Tate algebra). This enables us to generalize Anderson’s log-algebraicity theorem and an analogue of the Herbrand–Ribet theorem recently obtained by Taelman.
Optimal cycles in ultrametric dynamics and minimally ramified power series
Authors: Lindahl Karl-Olof , Rivera-Letelier Juan
Published: September 2015

We study ultrametric germs in one variable having an irrationally indifferent fixed point at the origin with a prescribed multiplier. We show that for many values of the multiplier, the cycles in the unit disk of the corresponding monic quadratic polynomial are ‘optimal’ in the following sense: they minimize the distance to the origin among cycles of the same minimal period of normalized germs having an irrationally indifferent fixed point at the origin with the same multiplier. We also give examples of multipliers for which the corresponding quadratic polynomial does not have optimal cycles. In those cases we exhibit a higher-degree polynomial such that all of its cycles are optimal. The proof of these results reveals a connection between the geometric location of periodic points of ultrametric power series and the lower ramification numbers of wildly ramified field automorphisms. We also give an extension of Sen’s theorem on wildly ramified field automorphisms, and a characterization of minimally ramified power series in terms of the iterative residue.
Performance Improvement for Proton Exchange Membrane Fuel Cell Using Hydrogen Pressure Pulsation Approach
Authors: Jia Qiuhong , Zhang Caizhi , Deng Bin , Han Ming
Published: September 2015

In a proton exchange membrane fuel cell (PEMFC), the hydrogen feed into the anode in a periodical pressure swing, so-called hydrogen pressure pulsation feed (HPPF), significantly affects the transport phenomena of hydrogen and water in the anode flow field. HPPF could adjust the distribution of the back diffusion water and the hydrogen partial pressure along the anode flow channels, improve hydrogen mass transfer in the anode flow field, and enhance the diffusion of hydrogen in the porous medium (anode diffusion layer). On the other hand, HPPF technique could mitigate the anode flooding issue caused by water back diffusion from the cathode, improve the fuel cell performance. In this work, the principle of HPPF technique was introduced and analyzed by a mathematic approach. Some of the important parameters used in HPPF technique, such as amplitude of pulsation pressure, pulsating frequency, etc., were experimentally investigated on dead-end mode PEMFC stack. The experimental results showed that the amplitude of pressure pulsation, pulsating frequency, and position applied for HPPF highly affected the performance of the PEMFC stack. It can be seen that higher the frequency and/or amplitude of pressure pulsation, the better the performance of PEMFC stack.
Investigation of Flow Aerodynamics for Optimal Fuel Placement and Mixing in the Radial Swirler Slot of a Dry Low Emission Gas Turbine Combustion Chamber
Authors: Eghe Agbonzikilo Festus , Owen Ieuan , Kumar Sadasivuni Suresh , Bickerton Ronald A.
Published: September 2015

This paper is concerned with optimizing the fuel–air mixing processes that take place within the radial swirler slot of a dry low emission (DLE) combustion system. The aerodynamics of the flow within the slot is complex and this, together with the placement of the fuel holes with cross injection, controls the mixing of the fuel and air. Computational fluid dynamics (CFD) with the shear stress transport (SST) (k–ω) turbulence model was used for flow and mixing predictions within the radial swirler slot and for conducting a CFD-based design of experiments (DOE) optimization study, in which different parameters related to the fuel injection holes were varied. The optimization study was comprised of 25 orthogonal design configurations in the Taguchi L25 orthogonal array (OA). The test domain for the CFD, and its experimental validation, was a large-scale representation of a swirler slot from the Siemens proprietary DLE combustion system. The DOE study showed that the number of fuel holes, injection hole diameter, and interhole distance are the most influential parameters for determining optimal fuel mixing. Consequently, the optimized mixing configuration obtained from the above study was experimentally tested on an atmospheric test facility. The mixing patterns from experiments at various axial locations across the slot are in good agreement with the mixing predictions from the optimal CFD model. The optimized fuel injection design improved mixing compared with the baseline design by about 60%.
Brush Seals Used in Steam Environments—Chronological Wear Development and the Impact of Different Seal Designs
Authors: Raben Markus , Friedrichs Jens , Helmis Thomas , Flegler Johan
Published: September 2015

During the last decades, turbo machine efficiency was considerably increased by using more efficient seals. Brush seals, as a compliant contacting filament seal, have become an attractive alternative to conventional labyrinth seals in the field of aircraft engines as well as in stationary gas and steam turbines. The aim of today's research related to brush seals is to understand the characteristics and their connections, in order to be able to make performance predictions, and to ensure the reliability over a defined operating period. The wear behavior is essentially influenced by frictional contacts at the seal-to-rotor interface during operation. For realistic investigations with representative circumferential velocities, the TU Braunschweig, Germany, operates a specially developed steam test rig which enables endurance investigations under varying operating steam conditions up to 50 bar and 450 °C. Wear measurements and the determination of seal performance characteristics, such as blow down and bristle stiffness, are enabled by an additional test facility, using pressurized cold air up to 8 bar as a working fluid. This work presents the chronological wear development on both rotor and seal sides in a steam test lasting 25 days or 11 days, respectively. Interruptions after stationary and transient intervals were made in order to investigate the degree of wear. Two different seal arrangements, a single tandem seal, and a two-stage single seal arrangement, using different seal elements were considered. Besides a continuous wear development, the results clearly show that the abrasive wear of the brush seal and rotor is mainly caused by transient test operations, particularly by enforced contacts during shaft excursions. Despite the increasing wear to the brushes, all seals have shown a functioning radial-adaptive behavior over the whole test duration with a sustained seal performance. Thereby, it could be shown that the two-stage arrangement displays a load shift during transients, leading to a balanced loading and unloading status for the two single brush seals. From load sharing, and in comparison with the wear data of the tandem seal arrangement, it can be derived that the two-stage seal is less prone to wear. However, the tandem seal arrangement, bearing the higher pressure difference within one configuration, shows a superior sealing performance under constant load, i.e., under stationary conditions.
Vehicle Dynamics Control by Using an Active Gyroscopic Device
Authors: Mashadi Behrooz , Gowdini Meysam
Published: September 2015

In this research, a gyroscopic device has been introduced for the purpose of vehicle handling enhancement. An optimal linear quadratic regulator controller (LQR) is designed based on the gyroscope–vehicle simple linear equations. This controller by using a gyroscope system is shown to enable the vehicle to follow the desired input. The desired vehicle dynamic motion is assumed in the form of the steady motion of the bicycle model. The desired motion for the gyroscope is a condition in which the gyroscope frame angular velocity is zero. A ten degrees-of-freedom (DOF) full vehicle model, consisting of 9DOF for the nonlinear vehicle model including the Magic Formula tire model and a nonlinear 1DOF gyroscope model, is used for the simulation purposes. In various maneuvers, the performance of the gyroscopic system with that of the conventional direct yaw moment control (DYC) system performance is compared. Simulation results show that on dry and slippery roads, the performances of gyroscope system and DYC are both desirable. On a μ-split road condition, DYC fails and is not effective whereas the gyroscope system has a very good performance.
Efficient Exhaustive Search of Power-Split Hybrid Powertrains With Multiple Planetary Gears and Clutches
Authors: Zhang Xiaowu , Eben Li Shengbo , Peng Huei , Sun Jing
Published: September 2015

Planetary gear (PG) power-split hybrid powertrains have been used in producing hybrid and plug-in hybrid vehicles from the Toyota, General Motor, and Ford for years. Some of the most recent designs use clutches to enable multiple operating modes to improve launching performance and/or fuel economy. Adding clutches and multiple operating modes, however, also increases production cost and design complexity. To enable an exhaustive but fast search for optimal designs among a large number of hardware configurations, clutch locations, and mode selections, an automated modeling and screening process is developed in this paper. Combining this process with the power-weighted efficiency analysis for rapid sizing method (PEARS), an optimal and computationally efficient energy management strategy, the extremely large design space of configuration, component sizing, and control becomes feasible to search through. This methodology to identify optimal designs has yet to be reported in the literature. A case study to evaluate the proposed methodology uses the configuration adopted in the Toyota Hybrid Synergy (THS-II) system used in the Prius model year 2010 and the Hybrid Camry. Two designs are investigated to compare with the simulated Prius design: one uses all possible operating modes; and the other uses a suboptimal design that limits the number of clutches to three.
Parameters Affecting Bubble Formation and Size Distribution From Porous Media
Authors: Shepard Thomas G. , Lee Jaiho , Yan Bo , Strykowski Paul J.
Published: September 2015

This paper describes the experiments designed to control bubble size during gas injection through porous media into liquid cross flow. A parametric study examined the effect of control variables on average bubble size and standard deviation. Results showed that for a given air and liquid flow rate, changing liquid channel height at the air injection site had the largest effect on bubble size and size distribution while varying porous media grade and electrolyte concentration had smaller, though significant, effects. In this study, the channel height was varied from 0.8 to 8 mm, porous media grade from 0.5 to 100 and salt concentration varied from zero to 3%. The resulting average bubble diameters were 0.085–2.5 mm.
Multiple Scattering of Flexural Waves on Thin Plates
Authors: Cai Liang-Wu , Hambric Stephen A.
Published: September 2015

In this paper, the scattering of flexural waves on a thin Kirchhoff plate by an ensemble of through-thickness circular scatterers is formulated by using the concept of the T-matrix in a generalized matrix notation, with a focus on deterministic numerical computations. T-matrices for common types of scatterers, including the void (hole), rigid, and elastic scatterers, are obtained. Wave field properties in the multiple-scattering setting, such as the scattering amplitude, and scattering cross section, as well as properties of the T-matrix due to the energy conservation are discussed. After an extensive validation, numerical examples are used to explore the band gap formation due to different types of scatterers. One of the interesting observations is that a type of inclusion commonly referred to as the “rigid inclusion” in fact represents a clamped boundary that is closer to a riveted confinement than a rigid scatterer; and an array of such scatterers can block the wave transmission at virtually all frequencies.
Space Radiator Optimization for Single-Phase Mechanical Pumped Fluid Loop
Authors: Kumar Rai Prashant , Rao Chikkala Simhachala , Adoni Abhijit A. , Kumar Dinesh
Published: September 2015

Advances in the design and development of communication spacecraft are associated with an increase in power consumption and heat dissipation in the spacecraft. As a consequence, advanced thermal control technologies like mechanical pumped fluid loop (MPFL) are increasingly being considered for spacecraft temperature management. These technologies generally use radiative sinks (often deployable) to reject heat. Since mass is a critical parameter in space applications, mass-optimized radiator design is paramount. This paper presents semi-analytical approach to evolve design of a mass-optimized space radiator panel for single-phase MPFL.
A Simplified Model for Effective Thermal Conductivity of Highly Porous Ceramic Fiber Insulation
Authors: Lumley Nicholas P. G. , Ford Emory , Minford Eric , Porter Jason M.
Published: September 2015

Highly porous ceramic fiber insulations are beginning to be considered as a replacement for firebrick insulations in high temperature, high pressure applications by the chemical process industry. However, the implementation of such materials has been impeded by a lack of experimental data and predictive models, especially at high gas pressure. The goal of this work was to develop a general, applied thermophysical model to predict effective thermal conductivity, keff, of porous ceramic fiber insulation materials and to determine the temperature, pressure, and gas conditions under which natural convection is a possible mode of heat transfer. A model was developed which calculates keff as the sum of conduction, convection, and radiation partial conductivities. The model was validated using available experimental data, including laboratory measurements made by this research effort. Overall, it was concluded that natural convection is indeed possible for the most porous insulations at pressures exceeding 10 atm. Furthermore, keff for some example insulations was determined as a function of temperature, pressure, and gas environment.
Optimization of an Algorithm for the Measurement of Unsteady Flow-Rates in High-Pressure Pipelines and Application of a Newly Designed Flowmeter to Volumetric Pump Analysis
Authors: Ferrari A. , Pizzo P.
Published: September 2015

An innovative, efficient, and robust algorithm is presented for the evaluation of the instantaneous flow-rate in high-pressure liquid flow pipelines. This algorithm is based on the pressure time histories measured at two locations. A simple ordinary differential equation has been derived from the mass and momentum conservation laws and has been solved analytically. This equation allows the flow-rate time fluctuations to be evaluated accurately around their mean value, without any need for initial datum on the liquid flow velocity. A measuring device has been designed and realized to evaluate the flow-rate. The proposed flowmeter layout consists of a piece of pipeline endowed with two piezoresistive pressure sensors equipped with miniaturized thermocouples, the pressure sensor conditioners and a central processing unit (CPU), in which the algorithm for the evaluation of the flow-rate has been implemented. A more sophisticated version of the flowmeter algorithm, which includes unsteady friction in the flow-rate evaluation, has also been developed. Different algorithm versions have been assessed and successfully validated through a comparison with numerical flow-rate data predicted using a reliable one-dimensional model of a common rail (CR) fuel injection system. The prototypal flowmeter has been installed at the delivery section of a CR volumetric pump in order to investigate the flow-rate ripple. The flowmeter traces have been compared with the predictions of a previously developed theoretical model for the pump delivered instantaneous flow-rate, in order to further assess the reliability of both the model and the flowmeter as well as to have a better understanding of the cause and effect relationships between the flow-rate time history and the dynamic working of the pump. The effects that the actuation of the fuel metering valve (FMV), which is placed at the CR pump inlet, has on the instantaneous delivered flow-rate have also been analyzed.
Numerical Comparison of Rotordynamic Characteristics for a Fully Partitioned Pocket Damper Seal and a Labyrinth Seal With High Positive and Negative Inlet Preswirl
Authors: Li Zhigang , Li Jun , Feng Zhenping
Published: September 2015

Pocket damper seals (PDSs) are used as replacements for labyrinth seals in high-pressure centrifugal compressors at the balance-piston location or center seal location to enhance rotordynamic stability. A concern exists that this enhanced stability will be lost at high positive inlet preswirl. Numerical results of frequency-dependent rotordynamic force coefficients and leakage flow rates were presented and compared for a fully partitioned PDS (FPDS) and a labyrinth seal at high positive and negative inlet preswirl, using a proposed transient computational fluid dynamics (CFD) method based on the multifrequency elliptical orbit whirling model. The negative preswirl indicates a fluid swirl in a direction opposite to rotor rotation at seal inlet. Both seals have identical diameter and sealing clearance. The full 3D concentric CFD model and mesh were built for the labyrinth seal and FPDS, respectively. The accuracy and availability of the present transient CFD numerical method were demonstrated with the experiment data of frequency-dependent rotordynamic coefficients of the labyrinth seal and FPDS at zero and high positive preswirl conditions. The numerical boundary conditions include two high positive preswirl, two high negative preswirl, and a zero preswirl. Numerical results show that the effect of inlet preswirl on the direct force coefficients is weak, but the effect on the cross-coupling stiffness and effective damping is dramatic. Both seals possess negative effective damping at lower excitation frequencies due to positive preswirl, and the crossover frequency of effective damping term increases with increasing positive preswirl. Negative preswirl produces negative cross-coupling stiffness and positive effective damping over the whole excitation frequency range. Increasing negative preswirl is a stabilizing factor for annular gas seals, which results in a significant increase in the effective damping and a decrease in the crossover frequency. It is desirable to reduce the inlet preswirl to zero or even negative through applications of negative-swirl brakes and negative injection devices.
Effect of Pipe Bend Configuration on Guided Waves-Based Defects Detection: An Experimental Study
Authors: Ni Jing , Zhou Shaoping , Zhang Pugen , Li Yong
Published: September 2015

Ultrasonic guided waves is one of the most effective nondestructive testing techniques, which has been successfully applied for damage detection and evaluation of piping components. However, research about defects detection for pipelines with multiple bends is still limited. In this paper, effect of pipe bend arrangement on guided waves-based defect detection is investigated by experimental method, in which different configurations including space-Z type, U type, and plane-Z type are considered, respectively. Finite element (FE) simulation is used to explore the propagation behaviors of axisymmetric L (0, 2) mode in different bend configurations. On this basis, the detection sensitivity for different crack locations is experimentally investigated. Simulation and experiment results reveal that feature of guided waves propagation across the first and the second bend is totally different, and the defect detection sensitivity in the second bend is different from that in the first bend.
Fabrication of Microfluidic Manifold by Precision Extrusion Deposition and Replica Molding for Cell-Laden Device
Authors: Snyder Jessica , Rin Son Ae , Hamid Qudus , Sun Wei
Published: September 2015

A PED (precision extrusion deposition)/replica molding process enables scaffold guided tissue engineering of a heterocellular microfluidic device. We investigate two types of cell-laden devices: the first with a 3D microfluidic manifold fully embedded in a PDMS (polydimethylsiloxane) substrate and the second a channel network on the surface of the PDMS substrate for cell printing directly into device channels. Fully embedded networks are leak-resistant with simplified construction methods. Channels exposed to the surface are used as mold to hold bioprinted cell-laden matrix for controlled cell placement throughout the network from inlet to outlet. The result is a 3D cell-laden microfluidic device with improved leak-resistance (up to 2.0 mL/min), pervasive diffusion and control of internal architecture.
Reduction of Physical and Constraint Degrees-of-Freedom of Redundant Formulated Multibody Systems
Authors: Stadlmayr Daniel , Witteveen Wolfgang , Steiner Wolfgang
Published: September 2015

Commercial multibody system simulation (MBS) tools commonly use a redundant coordinate formulation as part of their modeling strategy. Such multibody systems subject to holonomic constraints result in second-order d-index three differential algebraic equation (DAE) systems. Due to the redundant formulation and a priori estimation of possible flexible body coordinates, the model size increases rapidly with the number of bodies. Typically, a considerable number of constraint equations (and physical degrees-of-freedom (DOF)) are not necessary for the structure's motion but are necessary for its stability like out-of-plane constraints (and DOFs) in case of pure in-plane motion. We suggest a combination of both, physical DOF and constraint DOF reduction, based on proper orthogonal decomposition (POD) using DOF-type sensitive velocity snapshot matrices. After a brief introduction to the redundant multibody system, a modified flat Galerkin projection and its application to index-reduced systems in combination with POD are presented. The POD basis is then used as an identification tool pointing out reducible constraint equations. The methods are applied to one academic and one high-dimensional practical example. Finally, it can be reported that for the numerical examples provided in this work, more than 90% of the physical DOFs and up to 60% of the constraint equations can be omitted. Detailed results of the numerical examples and a critical discussion conclude the paper.