The effect of cooling the foil bearing on dynamics of the rotor-bearings system

In order to protect rotors and foil bearings operating at high temperatures from being overheated and damaged, these components are often cooled by air. In addition, such a cooling method is accompanied by an axial temperature gradient that changes the shape of the lubrication gap in a way likely to affect the operation of a foil bearing. This article presents the research on various methods for cooling a foil bearing and discusses the impact of these methods on dynamic parameters of the rotor-bearings system. To be able to assess the temperature inside such a bearing, there is a need for a reliable measurement method. The authors of the article measured the temperature of the top foil using thermocouples and showed that their measurement method does not exert any significant impact on the operation of the rotor-bearings system. The article also describes a novel method for compensating the axial temperature gradient occurring in the bearing bush using Peltier modules

CONTROL SYSTEM PREVENTING THERMAL GRADIENT DEVELOPMENT ON FOILS OF FOIL BEARING

This article presents attempts at automating a control system to reduce temperature scatter on the foil of a foil bearing. The control system reads the temperatures at six circumferential locations of the bearing’s foil and distributes control currents to the thermoelectric modules integrated into the bearing’s bushing. Three basic approaches have been proposed and tested: 1) a simple hot-spot tracking algorithm assigning predefined current values to the modules closest to the hot-spot location; 2) a tracking algorithm reducing abrupt changes in the control currents and, in effect, the local heat flux distribution; and 3) a tracking algorithm enhanced with a PID controller. The proposed controller has been implemented and compared to the performance of a temperature controller that does not have tracking capabilities. The implemented control strategies have proven the feasibility of temperature scatter reduction inside the investigated bearing. In most test cases, the instantaneous gradient reduction exceeded 50% (reaching 63% at its best)

RESTORING THE PASSIVITY OF SHUNT DAMPING CIRCUITS BASED ON THE SYNTHETIC INDUCTANCE BY THERMAL ENERGY HARVESTING

For decades people have used ambient energy, e.g., that of rushing streams or wind to obtain usable power. Starting with very low energy conversion, through constant development we have now reached the stage of extensive possibilities of harvesting the energy from the environment we live in. Today, there exist almost unconstrained opportunities to energize a broad spectrum of devices by energy available almost anywhere and of whichever form. One of the great advantages of energy harvesting is to make small electronic devices autonomous eliminating the need ofpower supply and mainte­nance. Shunt damping systems are unfavorably influenced by the size and mass of the coil inductors. While substituting bulky inductors with synthetic inductors one losses the passivity of the system gaining its practicability. Nevertheless, in order to outperform the actively driven systems, it is indispensable to return the passive properties of the system maintaining its performance. This paper presents the feasibility study ofpowering the passive shunt damping devices by the work that is lost irrevocably in a bearing node. The heat generated in a bearing is converted via the thermoelectric phenomenon and then used to power the synthetic inductance circuitry. In the paper it is shown that the required power levels can be satisfied by the thermoelectric generator paired to a moderately loaded bearing

Genomic organization of duplicated short wave-sensitive and long wave-sensitive opsin genes in the green swordtail, Xiphophorus helleri

<p>Abstract</p> <p>Background</p> <p>Long wave-sensitive (<it>LWS</it>) opsin genes have undergone multiple lineage-specific duplication events throughout the evolution of teleost fishes. <it>LWS </it>repertoire expansions in live-bearing fishes (family Poeciliidae) have equipped multiple species in this family with up to four <it>LWS </it>genes. Given that color vision, especially attraction to orange male coloration, is important to mate choice within poeciliids, <it>LWS </it>opsins have been proposed as candidate genes driving sexual selection in this family. To date the genomic organization of these genes has not been described in the family Poeciliidae, and little is known about the mechanisms regulating the expression of <it>LWS </it>opsins in any teleost.</p> <p>Results</p> <p>Two BAC clones containing the complete genomic repertoire of <it>LWS </it>opsin genes in the green swordtail fish, <it>Xiphophorus helleri</it>, were identified and sequenced. Three of the four <it>LWS </it>loci identified here were linked in a tandem array downstream of two tightly linked short wave-sensitive 2 (<it>SWS2</it>) opsin genes. The fourth <it>LWS </it>opsin gene, containing only a single intron, was not linked to the other three and is the product of a retrotransposition event. Genomic and phylogenetic results demonstrate that the <it>LWS </it>genes described here share a common evolutionary origin with those previously characterized in other poeciliids. Using qualitative RT-PCR and MSP we showed that each of the <it>LWS </it>and <it>SWS2 </it>opsins, as well as three other cone opsin genes and a single rod opsin gene, were expressed in the eyes of adult female and male <it>X. helleri</it>, contributing to six separate classes of adult retinal cone and rod cells with average λ_maxvalues of 365 nm, 405 nm, 459 nm, 499 nm, 534 nm and 568 nm. Comparative genomic analysis identified two candidate teleost opsin regulatory regions containing putative CRX binding sites and hormone response elements in upstream sequences of <it>LWS </it>gene regions of seven teleost species, including <it>X. helleri</it>.</p> <p>Conclusions</p> <p>We report the first complete genomic description of <it>LWS </it>and <it>SWS2 </it>genes in poeciliids. These data will serve as a reference for future work seeking to understand the relationship between <it>LWS </it>opsin genomic organization, gene expression, gene family evolution, sexual selection and speciation in this fish family.</p

Assignment of Atlantic salmon (Salmo salar) Linkage Groups to Specific Chromosomes: Conservation of Large Syntenic Blocks Corresponding to Whole Chromosome Arms in Rainbow Trout (Oncorhynchus mykiss)

Background: Most teleost species, especially freshwater groups such as the Esocidae which are theclosest relatives of salmonids, have a karyotype comprising 25 pairs of acrocentric chromosomes and 48–52 chromosome arms. After the common ancestor of salmonids underwent a whole genome duplication,its karyotype would have 100 chromosome arms, and this is reflected in the modal range of 96–104 seenin extant salmonids (e.g., rainbow trout). The Atlantic salmon is an exception among the salmonids as ithas 72–74 chromosome arms and its karyotype includes 12 pairs of large acrocentric chromosomes, whichappear to be the result of tandem fusions. The purpose of this study was to integrate the Atlantic salmon\u27slinkage map and karyotype and to compare the chromosome map with that of rainbow trout.Results: The Atlantic salmon genetic linkage groups were assigned to specific chromosomes in theEuropean subspecies using fluorescence in situ hybridization with BAC probes containing genetic markersmapped to each linkage group. The genetic linkage groups were larger for metacentric chromosomescompared to acrocentric chromosomes of similar size. Comparison of the Atlantic salmon chromosomemap with that of rainbow trout provides strong evidence for conservation of large syntenic blocks in thesespecies, corresponding to entire chromosome arms in the rainbow trout.Conclusion: It had been suggested that some of the large acrocentric chromosomes in Atlantic salmonare the result of tandem fusions, and that the small blocks of repetitive DNA in the middle of the armsrepresent the sites of chromosome fusions. The finding that the chromosomal regions on either side ofthe blocks of repetitive DNA within the larger acrocentric chromosomes correspond to different rainbowtrout chromosome arms provides support for this hypothesis

Comparative genomic analysis of Atlantic salmon, Salmo salar, from Europe and North America

Background: Several lines of evidence including allozyme analysis, restriction digest patterns and sequencing ofmtDNA as well as mini- and micro-satellite allele frequencies indicate that Atlantic salmon (Salmo salar) from NorthAmerica and Europe are genetically distinct. These observations are supported by karyotype analysis, whichrevealed that North American Atlantic salmon have 27 pairs of chromosomes whereas European salmon have 29pairs. We set out to construct a linkage map for a North American Atlantic salmon family and to compare this mapwith the well developed map for European Atlantic salmon.Results: We used microsatellite markers, which had previously been mapped in the two Atlantic salmon SALMAPmapping families from the River Tay, Scotland, to carry out linkage analysis in an Atlantic salmon family (NB1)whose parents were derived from the Saint John River stock in New Brunswick, Canada. As large differences inrecombination rates between female and male Atlantic salmon have been noted, separate genetic maps wereconstructed for each sex. The female linkage map comprises 218 markers in 37 linkage groups while the male maphas 226 markers in 28 linkage groups. We combined 280 markers from the female and male maps into 27composite linkage groups, which correspond to the haploid number of chromosomes in Atlantic salmon from theWestern Atlantic.Conclusions: A comparison of the composite NB1 and SALMAP linkage maps revealed the reason for thedifference in the chromosome numbers between European and North American Atlantic salmon: Linkage groupsAS-4 and AS-32 in the Scottish salmon, which correspond to chromosomes Ssa-6 and Ssa-22, are combined into asingle NB1 linkage group as are linkage groups AS-21 and AS-33 (corresponding to chromosomes Ssa-26 and Ssa-28). The comparison of the linkage maps also suggested some additional chromosomal rearrangements, but it willrequire finer mapping, potentially using SNPs, to test these predictions. Our results provide the first comparison ofthe genomic architecture of Atlantic salmon from North America and Europe with respect to chromosomeorganization

Comprehensive analysis of MHC class I genes from the U-, S-, and Z-lineages in Atlantic salmon

<p>Abstract</p> <p>Background</p> <p>We have previously sequenced more than 500 kb of the duplicated MHC class I regions in Atlantic salmon. In the IA region we identified the loci for the MHC class I gene <it>Sasa-UBA </it>in addition to a soluble MHC class I molecule, <it>Sasa-ULA</it>. A pseudolocus for <it>Sasa-UCA </it>was identified in the nonclassical IB region. Both regions contained genes for antigen presentation, as wells as orthologues to other genes residing in the human MHC region.</p> <p>Results</p> <p>The genomic localisation of two MHC class I lineages (Z and S) has been resolved. 7 BACs were sequenced using a combination of standard Sanger and 454 sequencing. The new sequence data extended the IA region with 150 kb identifying the location of one Z-lineage locus, <it>ZAA</it>. The IB region was extended with 350 kb including three new Z-lineage loci, <it>ZBA</it>, <it>ZCA </it>and <it>ZDA </it>in addition to a <it>UGA </it>locus. An allelic version of the IB region contained a functional <it>UDA </it>locus in addition to the <it>UCA </it>pseudolocus. Additionally a BAC harbouring two MHC class I genes (UHA) was placed on linkage group 14, while a BAC containing the S-lineage locus <it>SAA </it>(previously known as <it>UAA</it>) was placed on LG10. Gene expression studies showed limited expression range for all class I genes with exception of <it>UBA </it>being dominantly expressed in gut, spleen and gills, and <it>ZAA </it>with high expression in blood.</p> <p>Conclusion</p> <p>Here we describe the genomic organization of MHC class I loci from the U-, Z-, and S-lineages in Atlantic salmon. Nine of the described class I genes are located in the extension of the duplicated IA and IB regions, while three class I genes are found on two separate linkage groups. The gene organization of the two regions indicates that the IB region is evolving at a different pace than the IA region. Expression profiling, polymorphic content, peptide binding properties and phylogenetic relationship show that Atlantic salmon has only one MHC class Ia gene (<it>UBA</it>), in addition to a multitude of nonclassical MHC class I genes from the U-, S- and Z-lineages.</p

Detection of N-Glycolyl GM3 Ganglioside in Neuroectodermal Tumors by Immunohistochemistry: An Attractive Vaccine Target for Aggressive Pediatric Cancer

The N-glycolylated ganglioside NeuGc-GM3 has been described in solid tumors such as breast carcinoma, nonsmall cell lung cancer, and melanoma, but is usually not detected in normal human cells. Our aim was to evaluate the presence of NeuGc-GM3 in pediatric neuroectodermal tumors by immunohistochemistry. Twenty-seven archival cases of neuroblastoma and Ewing sarcoma family of tumors (ESFT) were analyzed. Formalin-fixed, paraffin-embedded tumor samples were cut into 5 μm sections. The monoclonal antibody 14F7, a mouse IgG1 that specifically recognizes NeuGc-GM3, and a peroxidase-labeled polymer conjugated to secondary antibodies were used. Presence of NeuGc-GM3 was evident in 23 of 27 cases (85%), with an average of about 70% of positive tumors cells. Immunoreactivity was moderate to intense in most tumors, showing a diffuse cytoplasmic and membranous staining, although cases of ESFT demonstrated a fine granular cytoplasmic pattern. No significant differences were observed between neuroblastoma with and without NMYC oncogene amplification, suggesting that expression of NeuGc-GM3 is preserved in more aggressive cancers. Until now, the expression of N-glycolylated gangliosides in pediatric neuroectodermal tumors has not been investigated. The present study evidenced the expression of NeuGc-GM3 in a high proportion of neuroectodermal tumors, suggesting its potential utility as a specific target of immunotherapy