bluuebunny/crossref_metadata_2025 huggingface dataset:
A complex gene locus enables xyloglucan utilization in the model saprophyte Cellvibrio japonicus
Authors: Larsbrink Johan , Thompson Andrew J. , Lundqvist Magnus , Gardner Jeffrey G. , Davies Gideon J. , Brumer Harry
Published: August 2014

The degradation of plant biomass by saprophytes is an ecologically important part of the global carbon cycle, which has also inspired a vast diversity of industrial enzyme applications. The xyloglucans (XyGs) constitute a family of ubiquitous and abundant plant cell wall polysaccharides, yet the enzymology of XyG saccharification is poorly studied. Here, we present the identification and molecular characterization of a complex genetic locus that is required for xyloglucan utilization by the model saprophyte Cellvibrio japonicus. In harness, transcriptomics, reverse genetics, enzyme kinetics, and structural biology indicate that the encoded cohort of an α‐xylosidase, a β‐galactosidase, and an α‐l‐fucosidase is specifically adapted for efficient, concerted saccharification of dicot (fucogalacto)xyloglucan oligosaccharides following import into the periplasm via an associated TonB‐dependent receptor. The data support a biological model of xyloglucan degradation by C. japonicus with striking similarities – and notable differences – to the complex polysaccharide utilization loci of the Bacteroidetes.
Symptoms induced by transgenic expression of p23 from Citrus tristeza virus in phloem‐associated cells of Mexican lime mimic virus infection without the aberrations accompanying constitutive expression
Authors: Soler Nuria , Fagoaga Carmen , López Carmelo , Moreno Pedro , Navarro Luis , Flores Ricardo , Peña Leandro
Published: August 2014

Citrus tristeza virus (CTV) is phloem restricted in natural citrus hosts. The 23‐kDa protein (p23) encoded by the virus is an RNA silencing suppressor and a pathogenicity determinant. The expression of p23, or its N‐terminal 157‐amino‐acid fragment comprising the zinc finger and flanking basic motifs, driven by the constitutive 35S promoter of cauliflower mosaic virus, induces CTV‐like symptoms and other aberrations in transgenic citrus. To better define the role of p23 in CTV pathogenesis, we compared the phenotypes of Mexican lime transformed with p23‐derived transgenes from the severe T36 and mild T317 CTV isolates under the control of the phloem‐specific promoter from Commelina yellow mottle virus (CoYMV) or the 35S promoter. Expression of the constructs restricted to the phloem induced a phenotype resembling CTV‐specific symptoms (vein clearing and necrosis, and stem pitting), but not the non‐specific aberrations (such as mature leaf epinasty and yellow pinpoints, growth cessation and apical necrosis) observed when p23 was ectopically expressed. Furthermore, vein necrosis and stem pitting in Mexican lime appeared to be specifically associated with p23 from T36. Phloem‐specific accumulation of the p23Δ158–209(T36) fragment was sufficient to induce the same anomalies, indicating that the region comprising the N‐terminal 157 amino acids of p23 is responsible (at least in part) for the vein clearing, stem pitting and, possibly, vein corking in this host.
A look into the Medical and Veterinary Entomology crystal ball
Authors: DANTAS‐TORRES F. , CAMERON M. M. , COLWELL D. D. , OTRANTO D.
Published: August 2014

Medical and Veterinary Entomology (MVE) represents a leading periodical in its field and covers many aspects of the biology and control of insects, ticks, mites and other arthropods of medical and veterinary importance. Since the first issue of the journal, researchers working in both developed and developing countries have published in MVE, with direct impact on current knowledge in the field. An increasing number of articles dealing with the epidemiology and transmission of vector‐borne pathogens have been published in MVE, reflecting rapid changes in vector distribution, pathogen transmission and host–arthropod interactions. This article represents a gaze into the crystal ball in which we identify areas of increasing interest, discuss the main changes that have occurred in the epidemiology of parasitic arthropods since the first issue of MVE, and predict the principal scientific topics that might arise in the next 25 years for scientists working in medical and veterinary entomology.
Identification of rickettsiae from wild rats and cat fleas in Malaysia
Authors: TAY S. T. , MOKHTAR A. S. , LOW K. C. , MOHD ZAIN S. N. , JEFFERY J. , ABDUL AZIZ N. , KHO K. L.
Published: August 2014

Rickettsioses are emerging zoonotic diseases reported worldwide. In spite of the serological evidence of spotted fever group rickettsioses in febrile patients in Malaysia, limited studies have been conducted to identify the animal reservoirs and vectors of rickettsioses. This study investigated the presence of rickettsiae in the tissue homogenates of 95 wild rats and 589 animal ectoparasites. Using PCR assays targeting the citrate synthase gene (gltA), rickettsial DNA was detected in the tissue homogenates of 13 (13.7%) wild rats. Sequence analysis of the gltA amplicons showed 98.6–100% similarity with those of Rickettsia honei/R. conorii/R. raoultii (Rickettsiales: Rickettsiaceae). Sequence analysis of outer membrane protein A gene (ompA) identified Rickettsia sp. TCM1 strain from two rats. No rickettsia was detected from Laelaps mites, Rhipicephalus sanguineus and Haemaphysalis bispinosa ticks, and Felicola subrostratus lice in this study. R. felis was identified from 32.2% of 177 Ctenocephalides felis fleas. Sequence analysis of the gltA amplicons revealed two genotypes of R. felis (Rf31 and RF2125) in the fleas. As wild rats and cat fleas play an important role in the enzoonotic maintenance of rickettsiae, control of rodent and flea populations may be able to reduce transmission of rickettsioses in the local setting.
Management strategies for achalasia
Authors: Vela M. F.
Published: August 2014

Treatment options for achalasia include oral pharmacologic therapy, endoscopic injection of botulinum toxin, pneumatic dilation, and myotomy (conventionally by laparoscopy, but more recently by an endoscopic approach). Oral pharmacologic agents have fallen out of use because of insufficient efficacy and frequent side effects. Endoscopic injection of botulinum toxin is safe and has good short‐term effectiveness, but as the effect invariably wears off after a few months, this treatment is reserved for patients who are not candidates for more definitive treatments. Pneumatic dilation and surgical myotomy are currently considered the most effective treatments, with similar effectiveness in randomized controlled trials with follow‐up of up to 2 years. The risk/benefit ratio and choice of therapy depend on patient characteristics (age, comorbidities, disease stage, prior treatments), patient's preference, and locally available expertise. Treatment of patients who fail or relapse after initial therapy is challenging and the success rate of pneumatic dilation or myotomy in this group is lower compared with previously untreated patients. The recently developed peroral endoscopic approach to myotomy has achieved excellent results in early uncontrolled studies, but high‐quality randomized trials are needed to ensure widespread adoption is reasonable. Finally, retrospective data suggest that achalasia subtypes as defined by high‐resolution esophageal pressure topography may guide treatment choice, but confirmation in prospective outcome studies is awaited.
Macrophages in diabetic gastroparesis – the missing link?
Authors: Neshatian L. , Gibbons S. J. , Farrugia G.
Published: August 2014

Background

Diabetic gastroparesis results in significant morbidity for patients and major economic burden for society. Treatment options for diabetic gastroparesis are currently directed at symptom control rather than the underlying disease and are limited. The pathophysiology of diabetic gastroparesis includes damage to intrinsic and extrinsic neurons, smooth muscle, and interstitial cells of Cajal (ICC). Oxidative damage in diabetes appears to be one of the primary insults involved in the pathogenesis of several complications of diabetes, including gastroparesis. Recent studies have highlighted the potential role of macrophages as key cellular elements in the pathogenesis of diabetic gastroparesis. Macrophages are important for both homeostasis and defense against a variety of pathogens. Heme oxygenase 1 (HO1), an enzyme expressed in a subset of macrophages has emerged as a major protective mechanism against oxidative stress. Activation of macrophages with high levels of HO1 expression protects against development of delayed gastric emptying in animal models of diabetes, while activation of macrophages that do not express HO1 are linked to neuromuscular cell injury. Targeting macrophages and HO1 may therefore be a therapeutic option in diabetic gastroparesis.

Purpose

This report briefly reviews the pathophysiology of diabetic gastroparesis with a focus on oxidative damage and how activation and polarization of different subtypes of macrophages in the muscularis propria determines development of delay in gastric emptying or protects against its development.
Exclusive breastfeeding is associated with reduced cow's milk sensitization in early childhood
Authors: Liao Sui‐Ling , Lai Shen‐Hao , Yeh Kuo‐Wei , Huang Yu‐Lin , Yao Tsung‐Chieh , Tsai Ming‐Han , Hua Men‐Chin , Huang Jing‐Long ,   The PATCH (The Prediction of Allergy in Taiwanese Children) Cohort Study
Published: August 2014

Background

Although breastfed infants have consistently been reported as having fewer infections and respiratory morbidity during infancy, none have reached a definitive conclusion as to whether breastfeeding is an effective strategy to prevent allergic diseases. This study aims to investigate the relationship between exclusive breastfeeding and sequential changes of several biomarkers of allergy, such as absolute eosinophil count, total IgE level, and specific IgE level during the first 3 yrs of life.

Methods

This is an unselected, population‐based study that is part of a prospective birth cohort called the PATCH (Prediction of Allergy in Taiwanese Children). Blood analysis was performed at ages 6, 12, 18, 24, and 36 months. Clinical records of breastfeeding and detailed questionnaires regarding to allergic diseases were also obtained.

Results

Analysis comparing exclusive breastfeeding ≥4 months with those <4 months and those partially breastfed showed a decreased risk of sensitization toward cow's milk protein up to the age of 2 yr (adjusted OR for cow's milk sensitization at 12 months was 0.2 [95% CI, 0.07–0.5]), at 18 months of age it was 0.2 [95% CI, 0.07–0.5], and at 24 months of age it was 0.2 [95% CI, 0.04–0.7]). In addition, although not significant, children of the exclusive breastfeeding group showed a trend of lower absolute eosinophil counts than their counterparts at all ages, and a lower total IgE level at the age of 3 yr.

Conclusions

Results of this study suggest that exclusive breastfeeding is associated with a reduced risk of cow's milk protein sensitization during early childhood.
Predictors of benefit from an atopic dermatitis education programme
Authors: Breuer Kristine , Matterne Uwe , Diepgen Thomas L. , Fartasch Manigé , Gieler Uwe , Kupfer Jörg , Lob‐Corzilius Thomas , Ring Johannes , Scheewe Sibylle , Scheidt Reginald , Schmid‐Ott Gerhard , Schnopp Christina , Staab Doris , Szczepanski Rüdiger , Wittenmeier Marita , Wahn Ulrich , Werfel Thomas
Published: August 2014

Background

Multidisciplinary, age‐related, structured, group educational programmes for children with atopic dermatitis (AD) and their parents have shown positive long‐term outcomes with respect to quality of life and coping behaviour of the participants. We aimed to identify predictors of favourable long‐term outcome of an education measure for parents of children with AD aged 3 months to 7 years in the framework of The German Atopic Dermatitis Intervention Study (GADIS).

Methods

In an exploratory approach, the data of 274 child–parent pairs were analysed with respect to the influence of various somatic and psychological variables as possible predictors of treatment success. Changes in parents' QoL, SCORAD (Scoring Atopic Dermatitis), topical corticosteroid use and parents' knowledge about AD between baseline and 12‐months' follow‐up were chosen as measures of long‐term treatment success (outcome).

Results

Psychological rather than somatic parameters were identified as predictors of treatment success. Parents who had negative treatment experiences in the past and possessed only poor coping abilities with regard to scratch control benefitted the most from the training programme. The outcome of the education measure was independent of parents' schooling, vocational level and income.

Conclusions

Parents of children with AD who lack adequate coping abilities should be particularly encouraged to take part in such an education programme.
Cross‐sectional comparison of the characteristics of respiratory allergy in immigrants and Italian children
Authors: Lombardi Carlo , Fiocchi Alessandro , Raffetti Elena , Donato Francesco , Canonica Giorgio Walter , Passalacqua Giovanni ,   The P‐IGRAM study group
Published: August 2014

Background

Immigrants represent a good epidemiological model to evaluate the relative influence of environmental and inherited factors on the development of allergy. Several studies on allergy in adults have been published, but few data in children are available. We aimed to investigate the differences, between Italian and immigrant children, in clinical characteristics of respiratory allergy.

Methods

This was a multicentre cross‐sectional study involving children born in Italy from Italian parents and children born either in Italy or abroad from immigrants. Children referred firstly for allergic respiratory disease (rhinitis/asthma), with an ascertained clinical diagnosis and IgE sensitization to inhalants, were included. Demographic features, comorbidities, severity of disease, and sensitization profile were compared between Italians and immigrants, separating also those born in Italy from immigrant parents and those born abroad.

Results

One hundred and sixty‐five immigrant allergic children were enrolled (100 male, mean age 8.3 yr), 128 of whose had both parents immigrated. Italian children were 237 (156 male, mean age 8.4 yr). The Italian and immigrant children were similar, apart from pet's ownership and family size. There was no difference in the severity of rhinitis/asthma between the groups, whereas significant differences were found in the pattern of sensitization: immigrant children were more frequently sensitized to house dust mites (73.3% vs. 51%, respectively; p = 0.002) and less to grass (41.8% vs. 57.8%; p = 0.002); this was retained also in monosensitized children. Immigrant children born in Italy (n = 105) had a lower prevalence of rhinitis vs. Italians (68.3% vs. 87.6%, respectively, p = 0.003) and of sensitization to grass (28.3% vs. 49.5%, respectively, p = 0.008). No difference was found among macro‐regions of origin and demographic or clinical features.

Conclusions

Immigrant children born either in Italy or abroad did not show significant differences in the clinical pattern of the respiratory allergic disease when compared to children born from Italian parents.
Nesting Habitat Creation Enhances Recruitment in a Predator‐Free Environment: Malaclemys Nesting at the Paul S. Sarbanes Ecosystem Restoration Project
Authors: Roosenburg Willem M. , Spontak Dana M. , Sullivan Sean P. , Matthews Eva L. , Heckman Melanie L. , Trimbath Ryan J. , Dunn Robert P. , Dustman Emily A. , Smith Lisa , Graham Leah J.
Published: August 2014

Aquatic turtles worldwide are plagued with habitat loss due to development and shoreline alteration that destroys the terrestrial–aquatic linkage which they must cross to reproduce successfully. Furthermore, nesting habitat loss can concentrate nesting, increasing nest predator efficiency. We describe how the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island created nesting habitat for Malaclemys terrapin (Diamondback Terrapin), and document nesting success in response to construction progress and the absence of raccoons and foxes, the primary nest predators. We monitored terrapin nests throughout the nesting seasons from 2002 to 2011 to determine overall and within‐nest survivorship. Female terrapins began nesting on the restoration project within 1 year but planned construction during the study eliminated some nesting areas and opened previously inaccessible areas. Overall, nest survivorship was considerably higher than mainland nesting areas due to the absence of raccoons and foxes on the island and within‐nest survivorship was similar. Egg size, hatchling size, and the frequency of shell scute anomalies were similar to other terrapin populations, suggesting normal developmental conditions on the island. We documented annual variation in hatchling size that correlated negatively with mean air temperature during the incubation season. Our results indicate that restored or created isolated island habitat can be located rapidly by terrapins and can become an important source of recruitment in regions where nesting habitat is limited and predation is high. Poplar Island illustrates how habitat loss and restoration can affect turtle populations by revealing the changes in nesting patterns and success in newly created, predator‐free habitat.
Correlation between levels of exhaled hydrogen sulfide and airway inflammatory phenotype in patients with chronic persistent asthma
Authors: Zhang Jing , Wang Xinmao , Chen Yahong , Yao Wanzhen
Published: August 2014

Background and objective

Endogenous hydrogen sulfide (H2S) may be a biomarker of asthma severity and activity. However, the relationship between exhaledH2Sand airway inflammation phenotypes in asthma remains unclear. This study examined associations between endogenousH2Sand chronic airway inflammatory phenotypes in patients with chronic persistent asthma.

Methods

One hundred forty‐eight patients (47 males, 101 females, 47.4 ± 15.3 years old) with chronic persistent asthma were enrolled. Induced sputum cells were examined, and patients were grouped according to sputum inflammatory cell composition. Baseline demographics,AsthmaControlTest (ACT) scores, spirometry data andH2Slevels in exhaled air and plasma were obtained for all patients.

Results

The eosinophilic, neutrophilic, mixed granulocytic and paucigranulocytic inflammation groups included 57 (38.5%), 28 (18.9%), 23 (15.5%) and 40 (27%) subjects, respectively. The paucigranulocytic group had the best lung function, and patients with eosinophilic inflammation had lowerACTscores than patients with paucigranulocytic findings. In the eosinophilic group, lower exhaledH2Swere found and exhaledH2Slevels were negatively correlated with sputum eosinophil counts (R = −0.428,P < 0.01). ExhaledH2Slevels were positively correlated with percent of predicted forced expiratory volume in 1 s (R = 0.567,P < 0.01) andACTscore (R = 0.519,P < 0.01).

Conclusions

ExhaledH2Smay be a useful marker of airway inflammation in asthma.
Prices and Supply Disruptions during Natural Disasters
Authors: Cavallo Alberto , Cavallo Eduardo , Rigobon Roberto
Published: August 2014

We study the daily behavior of supermarket prices and product availability following two recent natural disasters: the 2010 earthquake in Chile and the 2011 earthquake in Japan. In both cases there was an immediate and persistent effect on product availability. The number of goods available for sale fell 32 percent in Chile and 17 percent in Japan from the day of the disaster to its lowest point, which occurred 61 and 18 days after the earthquakes, respectively. Product availability recovered slowly, and a significant share of goods remained out of stock after six months. By contrast, prices were relatively stable and did not increase for months after the earthquakes, even for goods that were experiencing severe stockouts. These trends are present at all levels of aggregation, but appear strongly in non‐perishable goods and emergency products. Our findings shed light into the determinants of sticky prices in conditions where traditional adjustment costs are less important. In particular, we look at the frequency and magnitudes of price changes in both countries and find that the results in Chile are consistent with pricing models where retailers have fear of “customer anger”. In Japan, by contrast, the evidence suggests a bigger role for supply disruptions that restricted the ability of retailers to re‐stock goods after the earthquake.
Digital Volume Correlation Applied to X‐ray Tomography Images from Spherical Indentation Tests on Lightweight Gypsum
Authors: Bouterf A. , Roux S. , Hild F. , Adrien J. , Maire E. , Meille S.
Published: August 2014

Cylinders made of lightweight gypsum are extracted from industrial plasterboard and then indented in situ in an X‐ray tomograph. The results from the in situ experiment show that a compacted zone develops under the indenter, which is displaying a very sharp boundary with the undamaged material. Tomographic imaging during the mechanical load associated with digital volume correlation enables the displacement fields to be measured during the test. However, because of the inhomogeneous nature of the indentation test, a high spatial resolution for the displacement is called for, and because the range of displacement amplitudes is small, uncertainties on the measured displacement and strain fields are large. In this study, a new methodology is presented to address integrated digital volume correlation based on a library of fields computed from a commercial finite element software. It allows many fluctuations in the estimated displacement fields to be filtered out and the measurement to be much more robust and reliable. This opens new pathways for the identification of mechanical properties.
Randomized controlled trial using bosentan to enhance the impact of exercise training in subjects with type 2 diabetes mellitus
Authors: Schreuder Tim H. A. , Duncker Dirk J. , Hopman Maria T. E. , Thijssen Dick H. J.
Published: August 2014

New Findings

What is the central question of this study?

Does the addition of endothelin blockade improve the effect of an 8 week training programme on brachial and superficial femoral artery endothelium‐dependent and ‑independent dilatation and physical fitness in type 2 diabetes patients?

What is the main finding and its importance?

Training improved physical fitness but not vascular function in type 2 diabetes. Endothelin blockade had no additional effect on our outcome parameters, suggesting that despite acutely restoring blood flow, endothelin blockade does not potentiate the effect of training on vasculature or fitness in type 2 diabetes.

In type 2 diabetes patients, endothelin (ET) receptor blockade may enhance blood flow responses to exercise training. The combination of exercise training and ET receptor blockade may represent a more potent stimulus than training alone to improve vascular function, physical fitness and glucose homeostasis. We assessed the effect of an 8 week exercise training programme combined with either ET blockade or placebo on vasculature, fitness and glucose homeostasis in people with type 2 diabetes. In a double‐blind randomized controlled trial, brachial endothelium‐dependent and ‑independent dilatation (using flow‐mediated dilatation and glyceryl trinitrate, respectively), glucose homeostasis (using Homeostasis Model Assessment for Insulin Resistance (HOMA‐IR)) and physical fitness (maximal cycling test) were assessed in 18 men with type 2 diabetes (60 ± 6 years old). Subjects underwent an 8 week exercise training programme, with half of the subjects receiving ET receptor blockade (bosentan) and the other half a placebo, followed by reassessment of the tests above. Exercise training improved physical fitness to a similar extent in both groups, but we did not detect changes in vascular function in either group. This study suggests that there is no adaptation in brachial and femoral artery endothelial function after 8 weeks of training in type 2 diabetes patients. Endothelin receptor blockade combined with exercise training does not additionally alter conduit artery endothelial function or physical fitness in type 2 diabetes.
Renal sympathetic denervation modulates ventricular electrophysiology and has a protective effect on ischaemia‐induced ventricular arrhythmia
Authors: Huang Bing , Yu Lilei , He Bo , Lu Zhibing , Wang Songyun , He Wenbo , Yang Kang , Liao Kai , Zhang Ling , Jiang Hong
Published: August 2014

New Findings

What is the central question of this study?

It is well known that modulation of the autonomic nervous system affects cardiac electrophysiology. Renal sympathetic denervation has been shown to reduce systemic sympathetic activity. However, it is unknown whether renal sympathetic denervation could modulate ventricular electrophysiology and decrease the occurrence of ventricular arrhythmias associated with ischaemia.

What is the main finding and its importance?

Our data show that renal sympathetic denervation stabilizes ventricular electrophysiological properties in normal hearts and reduces the occurrence of ventricular arrhythmia in hearts experiencing acute myocardial ischaemia. These findings suggest that renal sympathetic denervation may become a new treatment option for ventricular arrhythmia.

Recently, a beneficial effect of renal sympathetic denervation (RSD) has been seen in patients with ventricular electrical storm. However, the effect of RSD on ventricular electrophysiology remains unclear. Thirty‐three mongrel dogs were included in the present study. Renal sympathetic denervation was performed by radiofrequency ablation of the adventitial surface of the renal artery. In group 1 (n = 8), programmed stimulation was performed before and after RSD to determine the ventricular effective refractory period (ERP) and action potential duration (APD) restitution properties. The same parameters were measured in five other animals that underwent sham RSD to serve as controls. In group 2 (n = 10), acute myocardial ischaemia (AMI) was induced by ligating the proximal left anterior descending coronary artery after the performance of RSD, and the incidence of ventricular arrhythmia (VA) was calculated during 1 h of recording. In another 10 dogs (group 3), AMI was induced and VA was measured with sham RSD. In group 1, RSD significantly prolonged ventricular ERP and APD, reduced the maximal slope (Smax) of the restitution curve and suppressed APD alternans at each site. Renal sympathetic denervation also significantly decreased the spatial dispersion of ERP, APD and Smax. In the five control animals, no significant electrophysiological change was detected after sham RSD. The occurrence of spontaneous VA during 1 h of AMI in group 2 was significantly lower than that in group 3. These data suggest that RSD stabilizes ventricular electrophysiological properties in normal hearts and reduces the occurrence of VA in hearts experiencing AMI.
Human lymphatic vessel contractile activity is inhibited in vitro but not in vivo by the calcium channel blocker nifedipine
Authors: Telinius Niklas , Mohanakumar Sheyanth , Majgaard Jens , Kim Sukhan , Pilegaard Hans , Pahle Einar , Nielsen Jørn , de Leval Marc , Aalkjaer Christian , Hjortdal Vibeke , Boedtkjer Donna Briggs
Published: August 2014

Key points

We studied the effects of antihypertensive calcium channel blockers on CaV1.2, the predominantly expressed L‐type calcium channel in the largest human lymphatic vessel, the thoracic duct.

Human lymphatic collecting vessels, both large and small, are highly‐sensitive in vitro to calcium channel blockers; exposure to these drugs inhibits endogenous lymphatic contractile activity and action potentials and diminishes noradrenaline‐induced phasic contractions.

In vivo administration of calcium channel blocker nifedipine to healthy volunteers did not reduce lymphatic contractile activity despite all subjects achieving nifedipine plasma concentrations comparable with those observed to affect contractile function in vitro.

These results indicate that calcium channel blocker‐related oedema is unlikely to be exacerbated by an off‐target effect of the drugs diminishing lymphatic pumping and fluid removal.

Calcium channel blockers (CCB) are widely prescribed anti‐hypertensive agents. The commonest side‐effect, peripheral oedema, is attributed to a larger arterial than venous dilatation causing increased fluid filtration. Whether CCB treatment is detrimental to human lymphatic vessel function and thereby exacerbates oedema formation is unknown. We observed that spontaneous lymphatic contractions in isolated human vessels (thoracic duct and mesenteric lymphatics) maintained under isometric conditions were inhibited by therapeutic concentrations (nanomolar) of the CCB nifedipine while higher than therapeutic concentrations of verapamil (micromolar) were necessary to inhibit activity. Nifedipine also inhibited spontaneous action potentials measured by sharp microelectrodes. Furthermore, noradrenaline did not elicit normal increases in lymphatic vessel tone when maximal constriction was reduced to 29.4 ± 4.9% of control in the presence of 20 nmol l−1 nifedipine. Transcripts for the L‐type calcium channel gene CACNA1C were consistently detected from human thoracic duct samples examined and the CaV1.2 protein was localized by immunoreactivity to lymphatic smooth muscle cells. While human lymphatics ex vivo were highly sensitive to nifedipine, this was not apparent in vivo when nifedipine was compared to placebo in a randomized, double‐blinded clinical trial: conversely, lymphatic vessel contraction frequency was increased and refill time was faster despite all subjects achieving target nifedipine plasma concentrations. We conclude that human lymphatic vessels are highly sensitive to nifedipine in vitro but that care must be taken when extrapolating in vitro observations of lymphatic vessel function to the clinical situation, as similar changes in lymphatic function were not evident in our clinical trial comparing nifedipine treatment to placebo.
Pressurized SOFC Hybrid Systems: Control System Study and Experimental Verification
Authors: Larosa Luca , Traverso Alberto , Ferrari Mario L. , Zaccaria Valentina
Published: August 2014

In this paper, two different advanced control approaches for a pressurized solid oxide fuel cell (SOFC) hybrid system are investigated and compared against traditional proportional integral derivative (PID). Both advanced control methods use model predictive control (MPC): in the first case, the MPC has direct access to the plant manipulated variables, in the second case, the MPC operates on the setpoints of PIDs which control the plant. In the second approach, the idea is to use MPC at the highest level of the plant control system to optimize the performance of bottoming PIDs, retaining system stability and operator confidence. Two MIMO (multi-input multi-output) controllers were obtained: fuel cell power and cathode inlet temperature are the controlled variables; fuel cell bypass flow, current and fuel mass flow rate (the utilization factor kept constant) are the manipulated variables. The two advanced control methods were tested and compared against the conventional PID approach using a SOFC hybrid system model. Then, the MPC controller was implemented in the hybrid system emulator test rig developed by the thermochemical power group (TPG) at the University of Genoa. Experimental tests were carried out to compare MPC against classic PID method: load following tests were carried out. Ramping the fuel cell load from 100% to 80% and back, keeping constant the target of the cathode inlet temperature, the MPC controller was able to reduce the mismatch between the actual and the target values of the cathode inlet temperature from 7 K maximum of the PID controller to 3 K maximum, showing more stable behavior in general.
Modeling the Gas Turbine Engine Under Its Dynamic Heating Conditions
Authors: Yepifanov Sergiy V. , Zelenskyi Roman L. , Loboda Igor
Published: August 2014

A modern gas turbine engine (GTE) is a complex nonlinear dynamic system with the mutual effect of gas-dynamic and thermal processes in its components. The engine development requires the precise real-time simulation of all main operating modes. One of the most complex operating modes for modeling is “cold stabilization,” which is the rotors acceleration without completely heated up the turbine elements. The dynamic heating problem is a topical practical issue. Solving the problem requires coordinating a gas-path model with heat and stress models, which is also a significant scientific problem. The phenomenon of interest is the radial clearances change during engines operation and its influence on engines static and dynamic performances. To consider the clearance change, it is necessary to synthesize the quick proceeding stress-state models (QPSSM) of a rotor and a casing for the initial temperature and dynamic heating. The unique feature of the QPSSM of GTEs is separate equation sets, which allow the heat exchange between structure elements and the gas (air) and the displacements of the turbine rotor and the casing. This ability appears as a result of determining the effect of each factor on different structural elements of the engine. The presented method significantly simplifies the model identification, which can be performed based on a precise calculation of the unsteady temperature fields of the structural elements and the variation of the radial clearance. Thus, the present paper addresses a new method to model the engine dynamics considering its heating up. The method is based on the integration of three models: the gas-path dynamics model, the clearance dynamics model, and the model of the clearance effect on the efficiency. The paper also comprises the program implementation of the models. The method was tested by applying to a particular turbofan engine.
ANFIS Driven Strain Control of Thin-Shape Memory Alloy Wires Using Seebeck Voltage of a Shape Memory Alloy–Constantan Thermocouple
Authors: Sriram Malladi V. V. N. , Tarazaga Pablo A.
Published: August 2014

Shape memory alloy (SMA) actuators exhibit considerable hysteresis between the supply voltage (conventionally used in resistive heating) and strain characteristics of the SMA. Hence, it is not easy to control the strain of a thin-SMA wire, unless a model is developed that can match the actuator's nonlinearities for predicting the supply voltage required by the SMA system accurately. The work presented in this paper proposes the use of a black-box technique called the adaptive neurofuzzy inference system (ANFIS) to study the hysteretic behavior of SMAs. The input parameters for such an ANFIS model would be a physical variable at time t and at a time t + n, where n is a time shift. The present work studies the effect of a time shift on the actuator nonlinearities for two ANFIS models. One of the models studies the relationship between the desired displacement of an SMA and the supply voltage across the SMA, while the other model predicts the actual displacement of an SMA from the feedback temperature. A novel SMA–Constantan thermocouple records the feedback temperature.
Dynamic Modeling and Experimental Validation of an Annular Dielectric Elastomer Actuator With a Biasing Mass
Authors: Rizzello Gianluca , Hodgins Micah , Naso David , York Alexander , Seelecke Stefan
Published: August 2014

This paper presents a model for the electromechanically coupled dynamic behavior of dielectric elastomer actuators (DEA). The main goal is to develop a lumped, dynamic model which can be used for the optimization of actuator design in specific applications as well as for the synthesis of high precision, model-based feedback control algorithms. A mass-biased membrane actuator with an annular geometry is chosen as a reference case to introduce the modeling concept. The mechanical model extends standard linear visco-elasticity through the introduction of a nonlinear hyperelastic Ogden element. Electromechanical coupling is implemented through the Maxwell stress concept. The DEA model is then experimentally calibrated and validated for both quasi static and dynamic loading conditions. It can be shown that both mechanical preloading and electric actuation can be reproduced over a relevant range of masses and frequencies.
Two-Dimensional Heat Transfer Distribution of a Rotating Ribbed Channel at Different Reynolds Numbers
Authors: Mayo Ignacio , Arts Tony , El-Habib Ahmed , Parres Benjamin
Published: August 2014

The convective heat transfer distribution in a rib-roughened rotating internal cooling channel was measured for different rotation and Reynolds numbers, representative of engine operating conditions. The test section consisted of a channel of aspect ratio equal to 0.9 with one wall equipped with eight ribs perpendicular to the main flow direction. The pitch to rib height ratio was 10 and the rib blockage was 10%. The test rig was designed to provide a uniform heat flux boundary condition over the ribbed wall, minimizing the heat transfer losses and allowing temperature measurements at significant rotation rates. Steady-state liquid crystal thermography (LCT) was employed to quantify a detailed 2D distribution of the wall temperature, allowing the determination of the convective heat transfer coefficient along the area between the sixth and eighth rib. The channel and all the required instrumentation were mounted on a large rotating disk, providing the same spatial resolution and measurement accuracy as in a stationary rig. The assembly was able to rotate both in clockwise and counterclockwise directions, so that the investigated wall was acting either as leading or trailing side, respectively. The tested Reynolds number values (based on the hydraulic diameter of the channel) were 15,000, 20,000, 30,000, and 40,000. The maximum rotation number values were ranging between 0.12 (Re = 40,000) and 0.30 (Re = 15,000). Turbulence profiles and secondary flows modified by rotation have shown their impact not only on the average value of the heat transfer coefficient but also on its distribution. On the trailing side, the heat transfer distribution flattens as the rotation number increases, while its averaged value increases due to the turbulence enhancement and secondary flows induced by the rotation. On the leading side, the secondary flows counteract the turbulence reduction and the overall heat transfer coefficient exhibits a limited decrease. In the latter case, the secondary flows are responsible for high heat transfer gradients on the investigated area.
Laminar Burning Velocities and Emissions of Hydrogen–Methane–Air–Steam Mixtures
Authors: Göckeler Katharina , Krüger Oliver , Paschereit Christian Oliver
Published: August 2014

Humidified gas turbines using steam generated from excess heat feature increased cycle efficiencies. Injecting the steam into the combustor reduces NOx emissions, flame temperatures, and burning velocities, promising a clean and stable combustion of highly reactive fuels such as hydrogen or hydrogen–methane blends. This study presents laminar burning velocities for methane and hydrogen-enriched methane (10 mol. % and 50 mol. %) at steam contents up to 30% of the air mass flow. Experiments were conducted on prismatic Bunsen flames stabilized on a slot-burner, employing OH planar laser-induced fluorescence (OH-PLIF) as an indicator for flame front areas. The experimental burning velocities agree well with results from one-dimensional simulations using the GRI 3.0 mechanism. Burning velocities reduce nonlinearly with ascending steam mole fractions and more rapid compared to simulations using “virtual H2O” stemming from a chemical influence on reactions. Hydrogen enrichment increases burning velocities, extending the flammability range toward leaner and more humid mixtures. Additionally, measured NOx and CO emissions reveal a strong reduction in NOx emissions for increasing steam dilution rates, whereas CO curves are shifted toward higher equivalence ratios.
Application of an Advanced Creep–Fatigue Procedure for Flexible Design of Steam Turbine Rotors Based on Fracture Mechanics Methods
Authors: Sheng Shilun , Almstedt Henning
Published: August 2014

The demand for steam turbine components is driven not only by high efficiency but also by high plant operational flexibility. Steam turbine rotors are therefore exposed to increased temperatures and increased number of stress cycles. These aspects should be considered for life-time prediction. Fracture mechanics methods are usually applied when crack like defects are detected not only for new rotors but also for rotor components in service. Based on the findings, a decision has to be made with respect to acceptability considering high temperature effects as well as the expected future operating regime. For defect analysis in the high temperature range, crack initiation and crack propagation under combined creep and fatigue loading need to be taken into account. Based on fracture mechanics methods and long-term testing data, an advanced creep–fatigue procedure for the evaluation of crack initiation and crack growth has been developed within the German Creep Group W14 for creep crack growth (CCG) behavior. Furthermore, recent studies show that the crack size for creep crack initiation (CCI) depends on material ductility and creep strain in the ligament. This paper demonstrates the industrial application of the abovementioned method for steam turbine rotor assessment, which has a focus on crack initiation and crack growth under creep–fatigue conditions. For crack initiation, a simplified approach based on defect size and material ductility is compared to a standard approach—two-criteria-diagram (2CD). For the advanced evaluation concept, the CCI criterion is combined for analysis with a creep–fatigue crack growth (CFCG) procedure. The benefit of the method especially for ductile material will be highlighted.
A Remotely Operated Aeroelastically Unstable Low Pressure Turbine Cascade for Turbomachinery Aeromechanics Education and Training—Remote Flutter Lab
Authors: Lucio Monaco , Bergmans John , Vogt Damian , Fransson Torsten H.
Published: August 2014

The use of advanced pedagogical methodologies in connection with advanced use of modern information technology for delivery enables new ways of communicating, of exchanging knowledge, and of learning that are gaining increasing relevance in our society. Remote laboratory exercises offer the possibility to enhance learning for students in different technical areas, especially to the ones not having physical access to laboratory facilities and thus spreading knowledge in a world-wide perspective. A new “Remote Flutter Laboratory” has been developed to introduce aeromechanics engineering students and professionals to aeroelastic phenomena in turbomachinery. The laboratory is world-wide unique in the sense that it allows global access for learners anywhere and anytime to a facility dedicated to what is both a complex and relevant area for gas turbine design and operation. The core of the system consists of an aeroelastically unstable turbine blade row that exhibits self-excited and self-sustained flutter at specific operating conditions. Steady and unsteady blade loading and motion data are simultaneously acquired on five neighboring suspended blades and the whole system allows for a distant-based operation and monitoring of the rig as well as for automatic data retrieval. This paper focuses on the development of the Remote Flutter Laboratory exercise as a hands-on learning platform for online and distant-based education and training in turbomachinery aeromechanics enabling familiarization with the concept of critical reduced frequency and of flutter phenomena. This laboratory setup can easily be used “as is” directly by any turbomachinery teacher in the world, free of charge and independent upon time and location with the intended learning outcomes as specified in the lab, but it can also very easily be adapted to other intended learning outcomes that a teacher might want to highlight in a specific course. As such it is also a base for a turbomachinery repository of advanced remote laboratories of global uniqueness and access. The present work documents also the pioneer implementation of the LabSocket System for the remote operation of a wind tunnel test facility from any Internet-enabled computer, tablet or smartphone with no end-user software or plug-in installation.
Multiple Neutral Axes in Bending of a Multiple-Layer Beam With Extremely Different Elastic Properties
Authors: Shi Yan , Rogers John A. , Gao Cunfa , Huang Yonggang
Published: August 2014

The multi-layer beam consisted of materials with extremely different elastic properties, such as silicon and Polydimethylsiloxane (PDMS), has many important applications. The Kirchhoff assumption that the straight lines normal to the midsurface remain normal after deformation does not hold any more. The energy method is used to establish a simple analytic model for multi-layered structures with extremely different elastic properties. The analytic model is validated by finite element analysis.
A Comprehensive Model for Assessing the Impact of Steel Cleanliness on Bearing Performance
Authors: Ai Xiaolan
Published: August 2014

Steel cleanliness as measured by nonmetallic inclusion content in steel plays a major role in affecting bearing durability. A high-fidelity virtual bearing life test model was developed to predict the impact of inclusions on bearing fatigue life. This model analyzes distributions of inclusion size, shape, orientation, and location, and computes stress alterations to bearing material due to inclusions and the resulting life reduction. Comparisons between model predictions and experimental test results were made, confirming the validity of the model. Parametric studies were conducted to explore the effects of inclusion counts, inclusion size distributions, and the effect of overall bearing size on bearing life. A regression equation was proposed based on simulation results, linking the bearing life reduction factor (LRF) to the accumulative inclusion length within the stressed volume under contact load.
Modified Ventilatory Response Characteristics to Exercise in Breath-Hold Divers
Authors: Roecker Kai , Metzger Jule , Scholz Tobias , Tetzlaff Kay , Sorichter Stephan , Walterspacher Stephan
Published: August 2014

Specific adjustments to repeated extreme apnea are not fully known and understood. While a blunted ventilatory chemosensitivity to CO2 is described for elite breath-hold divers (BHDs) at rest, it is unclear whether specific adaptations affect their response to dynamic exercise. Eight elite BHDs with a previously validated decrease in CO2 chemosensitivity, 8 scuba divers (SCDs), and 8 matched control subjects were included in a study where markers of ventilatory response, Fowler’s dead space, partial pressure of carbon dioxide (pCO2), and blood lactate concentrations during cycle exercise were measured. Maximal power output did not differ between the groups, but lactate threshold (θL) appeared at a significantly lowered respiratory compensation point (RCP) and at a higher VO2 for the BHDs. End-tidal (petCO2) and estimated arterial pCO2 (paCO2) were significantly higher in BHDs at θL, the RCP, and maximum exhaustion. BHDs showed a significantly (P < .01) slower breathing pattern in relation to a given tidal volume at a specific work rate. In summary, BHDs presented signs of a metabolic shift from aerobic to anaerobic energy supply, decreased chemosensitivity during exercise, and a distinct ventilatory-response pattern during cycle exercise that differs from SCDs and controls.